CTI VACUUM SEMINAR WELCOME TO CTI-CRYOGENICS’ VACUUM SEMINAR.

CTI VACUUM SEMINARCTI VACUUM SEMINAR

WELCOME TOWELCOME TOCTI-CRYOGENICS’CTI-CRYOGENICS’VACUUM SEMINARVACUUM SEMINAR

CTI-CRYOGENICSCTI-CRYOGENICS

What Is Vaccum ?What Is Vaccum ?


What Is VaWhat Is Vaccccum ?um ?

Nothing but a misspelled word !Nothing but a misspelled word !


Vacuum is the reduction in density of free Vacuum is the reduction in density of free gas molecules within a chamber.gas molecules within a chamber.

What Is VacWhat Is Vacuuuum ?m ?

CTI-CRYOGENICSCTI-CRYOGENICSA cubic centimeter of air contains aboutA cubic centimeter of air contains about30,000,000,000,000,000,000 (3x1030,000,000,000,000,000,000 (3x101919) molecules.) molecules.

Even at the highest vacuum levels achieved in a Even at the highest vacuum levels achieved in a laboratory, a square centimeter of chamber laboratory, a square centimeter of chamber

surface experiences 400,000,000 molecular strikes surface experiences 400,000,000 molecular strikes every second.every second.

A molecule of nitrogen (NA molecule of nitrogen (N22) travels with an ) travels with an averageaverage speed of 500 m/s - about that of a rifle bullet.speed of 500 m/s - about that of a rifle bullet.

At the best ultrahigh-vacuum level achieved, At the best ultrahigh-vacuum level achieved, 1010-12 -12 Torr, there are still 30,000 molecules per cmTorr, there are still 30,000 molecules per cm33..


Controlled AtmosphereControlled Atmosphere– Remove reactive gasesRemove reactive gases

Long Mean Free PathLong Mean Free Path– Reduce molecular density & collisionsReduce molecular density & collisions– Clear path for source materialClear path for source material

Attain Plasma ConditionsAttain Plasma Conditions– Constant pressure supporting an ionized gas Constant pressure supporting an ionized gas

environmentenvironment

Why Vacuum?Why Vacuum?


Terms and ConceptsTerms and Concepts Vacuum FundamentalsVacuum Fundamentals Cryopumping BasicsCryopumping Basics Ion Implant OptimizationIon Implant Optimization

Seminar ObjectivesSeminar Objectives

TERMS AND CONCEPTS:TERMS AND CONCEPTS:

Molecular MotionMolecular Motion PressurePressure EquilibriumEquilibrium FlowFlow Air CompositionAir Composition Surface CharacteristicsSurface Characteristics

Topics:Topics:

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Molecular MotionMolecular Motion

Kinetic Theory of MatterKinetic Theory of MatterCollisionsCollisions

DensityDensityMean-Free PathMean-Free Path

Molecules are Molecules are nevernever at rest.at rest.

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Molecular Motion - Molecular Motion - Kinetic Theory of MatterKinetic Theory of Matter


Molecules are Molecules are nevernever at rest.at rest.

Continual state of Continual state of rapid, random motion.rapid, random motion.


Molecules are Molecules are nevernever at at rest.rest.

Continual state of rapid, Continual state of rapid, random motion.random motion.

Gas molecules move in Gas molecules move in straight lines and many straight lines and many directions with various directions with various speeds.speeds.


Molecules continue to Molecules continue to move in a straight line move in a straight line until influenced off of that until influenced off of that line by an external force.line by an external force.

External forces are usually External forces are usually supplied by collisions with supplied by collisions with other objects.other objects.

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Molecular Motion - Molecular Motion - CollisionsCollisions

Contact with chamber Contact with chamber surfaces.surfaces.



Colliding with other Colliding with other molecules moving in molecules moving in different directions and different directions and with varying speeds.with varying speeds.




Actual motion is a Actual motion is a combination of these combination of these factors.factors.


As a result of these As a result of these collisions, the actual collisions, the actual path of a molecule would path of a molecule would appear random.appear random.

The number and The number and frequency of collisions a frequency of collisions a molecule experiences is molecule experiences is related to its speed and related to its speed and the density of molecules.the density of molecules.

Defined as the number Defined as the number of molecules in a of molecules in a volume: d = N/V.volume: d = N/V.

Density is a measure of Density is a measure of the number of the number of molecules in a volume molecules in a volume and indicates their and indicates their average separation.average separation.

The volume is generally The volume is generally a constant.a constant.

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Molecular Motion - Molecular Motion - DensityDensity

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Molecular Motion - Molecular Motion - Mean-Free PathMean-Free Path

Mean-Free Path is defined as Mean-Free Path is defined as the average distance a the average distance a molecule travels between molecule travels between collisions with other collisions with other molecules.molecules.

Determined by:Determined by:– Density and size of molecules Density and size of molecules – PressurePressure


For a fixed volume, For a fixed volume, the Mean-Free Path will be the Mean-Free Path will be

greater when molecules are greater when molecules are at a lower density . . . at a lower density . . .


For a fixed volume, For a fixed volume, the Mean-Free Path will be the Mean-Free Path will be

greater when molecules are greater when molecules are at a lower density . . . at a lower density . . .

. . . and shorter when . . . and shorter when molecules are at a molecules are at a

higher density.higher density.


Vacuum Facts and AnalogiesVacuum Facts and Analogies

Mean-Free PathBetween Collisions

Pressure(mm Hg)

MolecularDensity (cm3)

BaseballSeparation

Baseball PathBetween Collisions

Path Examples

760 10-2 10-5 10-9 10-12

2.5 x 1019 3.2 x 1014 3.2 x 1011 3.2 x 107 32,000

51,000 km51 km5.1 m.5 cm.67

1 yard 1/4 mile 50 miles

44 feet 690 miles 6.9 x 105

miles6.9 x 109

miles6.9 x 1012

milesNew York

to Chicago

3 Tripsto Moon

37 Tripsto Sun

and Back

1.2LightYears



Topics:Topics:

TERMS AND CONCEPTS:TERMS AND CONCEPTS:PressurePressure

Force applied over an area.Force applied over an area.

PRESSUREPRESSURE


A moving molecule has A moving molecule has momentum equal to its momentum equal to its mass times velocity.mass times velocity.


A moving molecule has momentum A moving molecule has momentum equal to its mass times velocity.equal to its mass times velocity.

When this molecule collides with a When this molecule collides with a chamber wall, its momentum is chamber wall, its momentum is transferred to the wall at that point.transferred to the wall at that point.


Subsequent collisions Subsequent collisions immediately add more immediately add more force over the wall area.force over the wall area.


Subsequent collisions immediately Subsequent collisions immediately add more force over the wall area. add more force over the wall area.

The total pressure is calculated by The total pressure is calculated by adding all of the forces supplied by adding all of the forces supplied by all of the molecules colliding with all all of the molecules colliding with all of the chamber walls.of the chamber walls.


1 Atmosphere (atm)1 Atmosphere (atm) = 760 Torr= 760 Torr= 1.013 x 10= 1.013 x 1055 Pa Pa= 14.7 lb/in= 14.7 lb/in22 (psi) (psi)

1 Torr = 1000 milliTorr (microns)1 Torr = 1000 milliTorr (microns)

UNITSUNITSofof

PRESSUREPRESSURE


AltitudeAltitudePressurePressure

} Space Shuttle} Low-Earth Satellites

}Aircraft

Science Balloons} Cirrus Clouds}

1010-12-12

100100

11

1010-4-4

1010-6-6

1010-8-8

1010-10-10

1010-2-2

1000 (1609)1000 (1609)

400 (644)400 (644)

200 (322)200 (322)

100 (161)100 (161)80 (129)80 (129)60 (97)60 (97)

40 (64)40 (64)

20 (32)20 (32)

TorrTorr miles (km)miles (km)

760760

PaPa

101044

100100

1010-2-2

1010-4-4

1010-8-8

11

101055

1010-10-10

1010-6-6

0 Sea Level0 Sea Level



Topics:Topics:

TERMS AND CONCEPTS:TERMS AND CONCEPTS:EquilibriumEquilibrium

Equilibrium Vapor PressureEquilibrium Vapor Pressure Surface EquilibriumSurface Equilibrium


State where as many molecules are State where as many molecules are condensing as are vaporizing.condensing as are vaporizing.

A very important concept related to cryopumps.A very important concept related to cryopumps.

EQUILIBRIUM VAPOR PRESSUREEQUILIBRIUM VAPOR PRESSURE

TERMS AND CONCEPTS:TERMS AND CONCEPTS:EquilibriumEquilibrium - Equilibrium Vapor Pressure - Equilibrium Vapor Pressure

In a chamber kept at a uniform In a chamber kept at a uniform temperature over time temperature over time (isothermal), molecules can exist (isothermal), molecules can exist in several states;in several states;– GasGas– LiquidLiquid– SolidSolid

Gas

Liquid/Solid


Equilibrium occurs when the Equilibrium occurs when the rate of gas molecules returning rate of gas molecules returning to the liquid/solid (condensing) to the liquid/solid (condensing) is equal to the rate of energetic is equal to the rate of energetic molecules becoming gaseous molecules becoming gaseous

(vaporizing).(vaporizing).


All elements (gases) have a All elements (gases) have a specific Saturation Pressure specific Saturation Pressure

for a given temperature - for a given temperature - called the “Equilibrium called the “Equilibrium

Vapor Pressure”. Vapor Pressure”.

Saturated Gas atEquilibrium Vapor

Pressure

1010-10 -10 1010-7 -7 1010-4 -4 1010-3 -3

Water 130K 153K 185K 198.5KWater 130K 153K 185K 198.5KArgon 23.7K 28.6K 35.9K 39.2KArgon 23.7K 28.6K 35.9K 39.2K



State where as many molecules are arriving State where as many molecules are arriving on a surface as are leaving.on a surface as are leaving.

A very important concept related to cryopumps.A very important concept related to cryopumps.

SURFACE EQUILIBRIUMSURFACE EQUILIBRIUM

TERMS AND CONCEPTS:TERMS AND CONCEPTS:EquilibriumEquilibrium - Surface Equilibrium - Surface Equilibrium

At lower density and At lower density and pressure, molecules no pressure, molecules no longer condense and longer condense and vaporize.vaporize.– Arrival is adsorptionArrival is adsorption– Departure is desorptionDeparture is desorption

TERMS AND CONCEPTS:TERMS AND CONCEPTS:EquilibriumEquilibrium - Surface Equilibrium - Surface Equilibrium

When the number of molecules When the number of molecules arriving on the chamber arriving on the chamber

surface (adsorbing) equals the surface (adsorbing) equals the number leaving the surface number leaving the surface

(desorbing), then the system (desorbing), then the system is in “Surface Equilibrium”. is in “Surface Equilibrium”.



Topics:Topics:

TERMS AND CONCEPTS:TERMS AND CONCEPTS:FlowFlow

Pumping SpeedPumping SpeedThroughputThroughput

ConductanceConductanceTypes - RegimesTypes - RegimesBackstreamingBackstreaming


Volume of gas that passes a plane in a Volume of gas that passes a plane in a known time.known time.

The most commonly used measure to evaluate The most commonly used measure to evaluate the performance of a high vacuum pump.the performance of a high vacuum pump.

PUMPING SPEEDPUMPING SPEED(Volumetric Flow)(Volumetric Flow)

UNITS OF SPEEDUNITS OF SPEEDLiters per SecondLiters per Second

Describes the volumetric Describes the volumetric gas flow in a pipe based gas flow in a pipe based on:on:– VolumeVolume– TimeTime

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Flow - Flow - Pumping SpeedPumping Speed

UNITS OF SPEEDUNITS OF SPEEDLiters per SecondLiters per Second t1 t2

Speed (S) =Volume (V)

Time (t)

V(t2 - t1)

TERMS AND CONCEPTS:TERMS AND CONCEPTS: FlowFlow

The volume of gas at a known pressure that The volume of gas at a known pressure that passes a plane in a known time.passes a plane in a known time.

THROUGHPUTTHROUGHPUT

UNITS OF THROUGHPUTUNITS OF THROUGHPUT Torr-Liters per SecondTorr-Liters per Second

Describes the volumetric Describes the volumetric gas flow in a pipe at a gas flow in a pipe at a specific pressure:specific pressure:– PressurePressure– VolumeVolume– TimeTime

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Flow - Flow - ThroughputThroughput

UNITS OF THROUGHPUTUNITS OF THROUGHPUTTorr-Liters per SecondTorr-Liters per Second t1 t2

Throughput (Q)Speed (S) X Pressure (P)=Volume (V)

Time (t)= X Pressure (P)

V(t2 - t1)

= X P


Can also be defined as:Can also be defined as:

The quantity of gas molecules entering the pump The quantity of gas molecules entering the pump in a given unit of time.in a given unit of time.

ThroughputThroughput equals equals PressurePressure times times SpeedSpeed

(Q (Q = P = P x x SS))

THROUGHPUTTHROUGHPUTFlow - Flow - ThroughputThroughput

TERMS AND CONCEPTS:TERMS AND CONCEPTS: Flow - Flow - ThroughputThroughput

As the cryo’s throughput goes up, the time to capacity As the cryo’s throughput goes up, the time to capacity goes down. Working at higher pressures means goes down. Working at higher pressures means

more frequent regens. more frequent regens.

UNITS OF THROUGHPUTUNITS OF THROUGHPUTTorr-Liters per SecondTorr-Liters per Second


TERMS AND CONCEPTS:TERMS AND CONCEPTS: Flow - Flow - ThroughputThroughput

A cryopump’s throughput is limited by its refrigerationA cryopump’s throughput is limited by its refrigerationcapacity.capacity.

There is a maximum throughput specified as the There is a maximum throughput specified as the constant flow of gas that can be supplied to a pump constant flow of gas that can be supplied to a pump without raising the temperature of the second stage without raising the temperature of the second stage

over 20 K - it is a measure of the cryopump’s over 20 K - it is a measure of the cryopump’s refrigeration capabilities.refrigeration capabilities.



A term used to describe the ability of gas to flow A term used to describe the ability of gas to flow through a vacuum system. through a vacuum system.

Generally, high conductance is better than low. Generally, high conductance is better than low. Vacuum system designers attempt to minimize Vacuum system designers attempt to minimize

conductance losses by using large diameter conductance losses by using large diameter tubes and no elbows. tubes and no elbows.

CONDUCTANCECONDUCTANCE

UNITS OF CONDUCTANCE:UNITS OF CONDUCTANCE: Liters per Second Liters per Second

For a For a roundround pipe, pipe, conductance depends conductance depends on the:on the:– Type of gas (M)Type of gas (M)– Temperature of pipe (T)Temperature of pipe (T)– Diameter of pipe (D)Diameter of pipe (D)– Length of pipe (L)Length of pipe (L)

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Flow - Flow - Conductance (in molecular flow)Conductance (in molecular flow)

Recommendation:Recommendation:Use big, short pipes.Use big, short pipes.

Cpipe k = TM

D3

Lwhere,

M is molecular weightT is in kelvinD is in centimetersL is in centimeters

For a For a cylindricalcylindrical pipe pipe elbowelbow the conductance the conductance is determined by:is determined by:– Diameter of pipeDiameter of pipe– Effective Length of elbowEffective Length of elbow– Angle of elbowAngle of elbow

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Flow - Flow - ConductanceConductance

UNITS OF CONDUCTANCEUNITS OF CONDUCTANCELiters per SecondLiters per Second

Conductance (C)

Length1 (L1) + Length2 (L2) =

1.33 () X Diam. (D)+ 180

L1 + L2 + 1.33 () X D= 180

L1

L2

Combined conductance Combined conductance of both straight pipes of both straight pipes and elbows is calculated and elbows is calculated by summing all by summing all individual segments.individual segments.

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Flow - Flow - ConductanceConductance

UNITS OF CONDUCTANCEUNITS OF CONDUCTANCELiters per SecondLiters per Second

Combined Conductance

=1

C1

+1

C2

+1

C3

1

Ctotal

C1 C2

C3


Flow regimes are characterized by Flow regimes are characterized by the mean-free path of the gas and the mean-free path of the gas and

dimensions of the system.dimensions of the system.

GAS FLOW REGIMESGAS FLOW REGIMES

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Flow - Flow - RegimesRegimes

TurbulentTurbulent– Irregular Flow, Many EddiesIrregular Flow, Many Eddies

ViscousViscous– Regular Flow, No EddiesRegular Flow, No Eddies

TransitionalTransitional– Mean-Free Path is Smaller Mean-Free Path is Smaller

than Pipe Diameterthan Pipe Diameter MolecularMolecular

– Molecules Independent of OthersMolecules Independent of Others

Gas Flow Regimes:Gas Flow Regimes:

TurbulentTurbulent– 760 Torr to 50 Torr760 Torr to 50 Torr

ViscousViscous– 50 Torr to 200 milliTorr50 Torr to 200 milliTorr

TransitionalTransitional– 200 milliTorr to 3 milliTorr200 milliTorr to 3 milliTorr

MolecularMolecular– 3 milliTorr or Below3 milliTorr or Below


Typical Flow Ranges In Roughing Lines:Typical Flow Ranges In Roughing Lines:


DiameterDiameter

Gas Flow RegimesGas Flow Regimes

Data based on Nitrogenat a Temperature of 20o C

10-6 10-5 10-4 10-3 10-2 10-1 1 10 102 (Torr)

Viscous Viscous FlowFlowTransitional Transitional

FlowFlow

Molecular Molecular FlowFlow

103

102

10

1

10-1

10-2

PressurePressure10-4 10-3 10-2 10-1 1 10 102 103 104 (Pa)

104

103

102

10

1

(inches)(mm)


Migration of pump fluid molecules Migration of pump fluid molecules from the rough vacuum pump from the rough vacuum pump toward the vacuum chamber.toward the vacuum chamber.

BACKSTREAMINGBACKSTREAMING

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Flow - Flow - BackstreamingBackstreaming

Kinetic TheoryKinetic Theory– Molecules are Molecules are nevernever at rest. at rest.– Continual state of rapid, Continual state of rapid,

random motion.random motion.– Gas molecules move in Gas molecules move in

straight lines and many straight lines and many directions with various directions with various speeds.speeds.


Viscous Flow Viscous Flow (50 Torr - 200 milliTorr)(50 Torr - 200 milliTorr)– Molecules are directed in Molecules are directed in

uniform motion toward uniform motion toward lower pressurelower pressure

– Random motion of a Random motion of a molecule is influenced molecule is influenced in the direction of the in the direction of the mass flowmass flow

– Molecular motion Molecular motion “against” mass flow “against” mass flow unlikelyunlikely

Process Chamber

Low P

High PRough

Line

RoughValve

RoughPump

Transitional Flow Transitional Flow (200 milliTorr - 3 milliTorr)(200 milliTorr - 3 milliTorr)– The Mean-Free-Path is The Mean-Free-Path is

less than the diameter of less than the diameter of the rough linethe rough line

– Molecules collide with Molecules collide with other molecules and other molecules and rough line wallsrough line walls


Process Chamber

CollisionsWith Walls

AndMolecules

Transitional Flow Transitional Flow (200 milliTorr - 3 milliTorr)(200 milliTorr - 3 milliTorr)– Molecular density is such Molecular density is such

that there is still an that there is still an overall flow in the overall flow in the direction of the pumpdirection of the pump

– Enough separation Enough separation between molecules between molecules for some to migrate for some to migrate in other direction in other direction - backstreaming - backstreaming


Process Chamber

Chamber

Pump

Oil

Molecular Flow Molecular Flow (3 milliTorr and less)(3 milliTorr and less)– The Mean-Free-Path is The Mean-Free-Path is

greater than the diameter greater than the diameter of the rough lineof the rough line

– Molecules do not interact Molecules do not interact with other moleculeswith other molecules

– Progression down rough Progression down rough line toward rough pump line toward rough pump is with random motionis with random motion


Process Chamber

At the molecular level,At the molecular level,the physical world changes. the physical world changes.

CollisionsWith Walls

Only

Molecular Flow Molecular Flow (3 milliTorr and less)(3 milliTorr and less)– Molecules randomly Molecules randomly

move in either direction move in either direction - to or away from rough - to or away from rough pump and vacuum pumppump and vacuum pump

– Backstreaming Backstreaming probable in this probable in this flow regimeflow regime


Process Chamber

Pump

Chamber

Oil



Topics:Topics:

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Air CompositionAir Composition

Air ConstituentsAir ConstituentsAtmospheric PressuresAtmospheric Pressures

Vacuum PressuresVacuum Pressures

COMPOSITION OF ATMOSPHERIC AIRCOMPOSITION OF ATMOSPHERIC AIR(50% Humidity at 20(50% Humidity at 20oo C) C)

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Air Composition - Air Composition - Air ConstituentsAir Constituents

Percent by Volume

Nitrogen (NNitrogen (N22)) 78% 78% Oxygen (OOxygen (O22)) 21%21%Argon (Ar)Argon (Ar) .95%.95%Water (HWater (H22O)O) .75%.75%Carbon Dioxide (COCarbon Dioxide (CO22)) .03%.03%Neon (Ne)Neon (Ne) .0018%.0018%Helium (He)Helium (He) .000524%.000524%

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Air Composition - Air Composition - Atmospheric PressuresAtmospheric Pressures

Nitrogen: 78%Nitrogen: 78%

Pressures Above 10Pressures Above 10-3-3 Torr Torr



Oxygen: 21%Oxygen: 21%



Water: 1%Water: 1%

Oxygen: 21%Oxygen: 21%



TERMS AND CONCEPTS:TERMS AND CONCEPTS:Air Composition - Air Composition - Vacuum PressuresVacuum Pressures

Pressures Pressures BelowBelow 10 10-3-3 Torr Torr

Oxygen: <1%Oxygen: <1%

Nitrogen: <1%Nitrogen: <1%

Pressures Pressures BelowBelow 10 10-3-3 Torr Torr

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Air Composition - Air Composition - Vacuum PressuresVacuum Pressures



Water: 98%Water: 98%



Topics:Topics:

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Surface CharacteristicsSurface Characteristics

Polar MoleculesPolar MoleculesSurface LayeringSurface Layering

OutgassingOutgassing

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Surface CharacteristicsSurface Characteristics

Asymmetric gas molecules with one end Asymmetric gas molecules with one end charged positive and the other end charged positive and the other end

charged negative.charged negative.

POLAR MOLECULESPOLAR MOLECULES

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Surface Characteristics - Surface Characteristics - Polar MoleculesPolar Molecules

A water molecule is made-A water molecule is made-up of two hydrogen atoms up of two hydrogen atoms with positive charges and with positive charges and one oxygen atom with a one oxygen atom with a negative charge.negative charge.

The 105The 105oo molecular bond molecular bond orientation results in orientation results in opposite sides having opposite sides having different polarities.different polarities.

OH

H

-+

+105o

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Chamber Characteristics - Chamber Characteristics - Polar MoleculesPolar Molecules

Asymmetric molecules Asymmetric molecules like water are called like water are called “polar” . “polar” .

Polar molecules are Polar molecules are attracted to other attracted to other molecules and surfaces molecules and surfaces with an opposite charge.with an opposite charge.

OH

H

--+

+This ability to attach to other objects is why This ability to attach to other objects is why

water is so useful in chemistry and other water is so useful in chemistry and other sciences, and such a problem in vacuum sciences, and such a problem in vacuum

technology.technology.

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Chamber Characteristics - Chamber Characteristics - Polar MoleculesPolar Molecules

Water is the primary gas Water is the primary gas at vacuum pressures at vacuum pressures because it is a polar because it is a polar molecule.molecule.

The polarity of water The polarity of water and other molecules and other molecules results in surface results in surface layering on vacuum layering on vacuum chamber walls.chamber walls.

Pressures Below 10Pressures Below 10-3-3 Torr Torr



Water: 98%Water: 98%

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Chamber CharacteristicsChamber Characteristics

Vacuum chamber walls exposed to atmospheric Vacuum chamber walls exposed to atmospheric air and process gases will have a significant air and process gases will have a significant

amount of water and other molecules amount of water and other molecules temporarily attached as layers.temporarily attached as layers.

SURFACE LAYERINGSURFACE LAYERING

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Chamber Characteristics - Chamber Characteristics - Surface LayeringSurface Layering

Vacuum Chamber WallVacuum Chamber WallSingle Layer of Stable OxidesSingle Layer of Stable Oxides

1-2 Layers Chemisorbed Water, H1-2 Layers Chemisorbed Water, H22, O, O22, N, N22

5-100 Layers of Physisorbed Water5-100 Layers of Physisorbed Water

1-2 Layers of H1-2 Layers of H22, CO, Residual Gases, CO, Residual Gases

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Chamber CharacteristicsChamber Characteristics

Outgassing is the process by which Outgassing is the process by which atmospheric and other gases evolve atmospheric and other gases evolve

from chamber surfaces when exposed from chamber surfaces when exposed to high vacuum.to high vacuum.

The outgassing rate is measured inThe outgassing rate is measured intorr-liters per second per cmtorr-liters per second per cm22..

OUTGASSINGOUTGASSING

TERMS AND CONCEPTS:TERMS AND CONCEPTS:Chamber Characteristics - Chamber Characteristics - OutgassingOutgassing

Outgassing depends on Outgassing depends on several factors:several factors:– Gas CharacteristicsGas Characteristics


Outgassing depends on Outgassing depends on several factors:several factors:– Gas CharacteristicsGas Characteristics– Surface TemperatureSurface Temperature


Outgassing depends on Outgassing depends on several factors:several factors:– Gas CharacteristicsGas Characteristics– Surface TemperatureSurface Temperature– Exposure Time to Exposure Time to

VacuumVacuum

These factors, combined with polar These factors, combined with polar properties, contribute to water being properties, contribute to water being

such a problem at high vacuum.such a problem at high vacuum.


The quantity of evolved The quantity of evolved gas is the chamber gas is the chamber volume times the volume times the pressure change pressure change (Torr-liters). (Torr-liters).

The outgassing rate, or The outgassing rate, or quantity of gas evolved quantity of gas evolved over time, is measured over time, is measured in Torr-liters per second in Torr-liters per second per cmper cm22..

VACUUM FUNDAMENTALS:VACUUM FUNDAMENTALS:

Vacuum is the reduction in density of freeVacuum is the reduction in density of freegas molecules within a chamber.gas molecules within a chamber.

What Is Vacuum ?What Is Vacuum ?


Vacuum LevelsVacuum Levels Molecular Motion RevisitedMolecular Motion Revisited Chamber EvacuationChamber Evacuation Vacuum PumpsVacuum Pumps

Topics:Topics:

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum LevelsVacuum Levels

PressurePressure 10-12

100

1

10-4

10-6

10-8

10-10

10-2

200 (322)

100 (161)80 (129)60 (97)

40 (64)

20 (32)

Torr

1000 (1609)

400 (644)

miles (km)

760

Pa

104

100

10-2

10-4

10-8

1

105

10-10

10-6

0 Sea Level

Ultra-HighUltra-HighVacuumVacuum

HighHighVacuumVacuum

RoughRoughVacuumVacuum

Typical Typical Semiconductor Semiconductor Base PressuresBase Pressures

{{Semiconductor Semiconductor

Process PressuresProcess Pressures

AltitudeAltitude



Topics:Topics:

VACUUM FUNDAMENTALS:VACUUM FUNDAMENTALS:Molecular Motion Revisited - Molecular Motion Revisited - Kinetic TheoryKinetic Theory

Molecules are Molecules are nevernever at rest. at rest. Continual state of rapid, Continual state of rapid,

random motion.random motion. Gas molecules move in Gas molecules move in

straight lines and many straight lines and many directions with various directions with various speeds.speeds.

VACUUM FUNDAMENTALS:VACUUM FUNDAMENTALS:Molecular Motion Revisited - Molecular Motion Revisited - Kinetic TheoryKinetic Theory

Molecules continue to Molecules continue to move in a straight line move in a straight line until influenced off of that until influenced off of that line by an external force.line by an external force.

External forces are usually External forces are usually supplied by collisions with supplied by collisions with other objects.other objects.

VACUUM FUNDAMENTALS:VACUUM FUNDAMENTALS:Molecular Motion Revisited - Molecular Motion Revisited - CollisionsCollisions



Actual motion is a Actual motion is a combination of these combination of these factors.factors.

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Molecular Motion Revisited - Molecular Motion Revisited - CollisionsCollisions

As a result of the As a result of the molecule’s speed and molecule’s speed and these collisions, its these collisions, its motion appears as a motion appears as a random path about the random path about the enclosure.enclosure.

Over time, a molecule will Over time, a molecule will contact many other contact many other molecules and chamber molecules and chamber surfaces.surfaces.



Topics:Topics:

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Chamber EvacuationChamber Evacuation

If an opening were If an opening were placed in the chamber placed in the chamber wall, then eventually a wall, then eventually a molecule’s path would molecule’s path would be directed through that be directed through that opening.opening.

If an opening were If an opening were placed in the chamber placed in the chamber wall, then eventually a wall, then eventually a molecule’s path would molecule’s path would be directed through that be directed through that opening.opening.

Then, capturing the Then, capturing the molecule would prevent molecule would prevent its return to the its return to the chamber.chamber.


Over time, more Over time, more molecules will pass molecules will pass through the opening through the opening and be captured.and be captured.



As this occurs, fewer As this occurs, fewer and fewer molecules and fewer molecules remain in the chamber.remain in the chamber.



As this occurs, fewer As this occurs, fewer and fewer molecules and fewer molecules remain in the chamber.remain in the chamber.

Finally, only a fraction Finally, only a fraction of the original number of the original number of molecules are left. of molecules are left.



In an In an actual process chamber actual process chamber the “air gases” (Nthe “air gases” (N22, O, O22, etc.) , etc.)

are evacuated from are evacuated from atmosphere by vacuum atmosphere by vacuum

pumps very quickly.pumps very quickly.

But, because water vapor But, because water vapor remains on chamber walls remains on chamber walls

and the gas is now in and the gas is now in molecular flow, pumpdown molecular flow, pumpdown

slows considerably.slows considerably.

Oxygen: <1%

Nitrogen: <1%

Water: 98%

Pressures Below 10Pressures Below 10-3-3 Torr Torr



Topics:Topics:

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum PumpsVacuum Pumps

Types:Types:Diffusion PumpDiffusion Pump

TurbopumpTurbopumpCryopumpCryopumpWaterpumpWaterpump

Pumping System RangesPumping System RangesCrossoverCrossover

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum Pumps - Vacuum Pumps - TypesTypes

CAPTURECryopumpCryopump

Ion PumpIon Pump

THROUGHPUTDiffusion PumpDiffusion Pump

TurbopumpTurbopump

SPECIALIZED CAPTUREWaterpumpWaterpump

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum Pumps - Vacuum Pumps - Diffusion PumpDiffusion Pump

Characteristics:Characteristics:– Relatively good vacuumRelatively good vacuum– Long operational lifetimeLong operational lifetime– No moving partsNo moving parts– Minimal maintenanceMinimal maintenance– Oil backstreamingOil backstreaming– Heat input effectsHeat input effects– Require water coolingRequire water cooling– Mechanical pump required for Mechanical pump required for

discharge discharge – Limited orientations Limited orientations

Throughput Type Pump

Flange

Oil Boiler

CoolingCoils

Jets

Heater

PumpBody

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum Pumps - Vacuum Pumps - TurbopumpTurbopump

Flange

Outlet

RotorBlades

Inlet

Motor Assembly

PumpBody

StatorBlades


Characteristics:Characteristics:– Relatively clean and Relatively clean and

simple operationsimple operation– Fast start-upFast start-up– Pumping speed about Pumping speed about

equal for all gasesequal for all gases– Low water speedLow water speed– Low compression ratio Low compression ratio

for light gasesfor light gases– Multiple orientationsMultiple orientations

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum Pumps - Vacuum Pumps - TurbopumpTurbopump

Flange

Outlet

RotorBlades

Inlet

Motor Assembly

PumpBody

StatorBlades


Characteristics:Characteristics:– Bearing maintenanceBearing maintenance– Susceptible to Susceptible to

contaminationcontamination– High cost for liters/secHigh cost for liters/sec

4” 6” 8” 10” 16”4” 6” 8” 10” 16”

Water 200 400 900 1,300 4,000Water 200 400 900 1,300 4,000Air (NAir (N22) 68 280 550 1,000 3,400) 68 280 550 1,000 3,400Hydrogen 45 210 510 1,150 3,200Hydrogen 45 210 510 1,150 3,200Argon 57 235 462 840 2,856Argon 57 235 462 840 2,856

PUMPING SPEEDSPUMPING SPEEDS(liters/second)(liters/second)

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum Pumps - Vacuum Pumps - CryopumpCryopump

Characteristics:Characteristics:– Cleanest high vacuum Cleanest high vacuum

pumppump– No fluids, lubricants, or No fluids, lubricants, or

moving partsmoving parts– High crossover capability High crossover capability

minimizes backstreamingminimizes backstreaming– Highest pumping speedsHighest pumping speeds– Tailorable pumping speedsTailorable pumping speeds– Fast system pumpdownFast system pumpdown

Flange

CentralProcessor

VacuumVessel

1st StageArray

2nd StageArray

RadiationShield

Capture Type Pump

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum Pumps - Vacuum Pumps - CryopumpCryopump

Characteristics:Characteristics:– Operates in all orientations Operates in all orientations – Limited He capacityLimited He capacity– RegenerationRegeneration– Thermal shielding for high Thermal shielding for high

temperature sourcestemperature sources

Flange

CentralProcessor

VacuumVessel

1st StageArray

2nd StageArray

RadiationShield

Capture Type Pump

4” 8” 8”(F) 10” 16”4” 8” 8”(F) 10” 16”

Water 1,100 4,000 4,000 9,000 16,000Water 1,100 4,000 4,000 9,000 16,000Air 370 1,500 1,500 3,000 6,000Air 370 1,500 1,500 3,000 6,000Hydrogen 370 2,500 2,200 5,000 12,000Hydrogen 370 2,500 2,200 5,000 12,000Argon 310 1,200 1,200 2,500 5,000Argon 310 1,200 1,200 2,500 5,000


VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum Pumps - Vacuum Pumps - WaterpumpWaterpump

Features:Features:– ““Booster” pumpBooster” pump– High water vapor pumpingHigh water vapor pumping– Does not condense Does not condense

process gasesprocess gases– Can be located inside Can be located inside

chamber - speed not chamber - speed not limited by port sizelimited by port size

Specialized Capture Type Pump

4” 6” 8” 10” 16”4” 6” 8” 10” 16”

Water 1,100 2,500 4,000 7,000 16,000Water 1,100 2,500 4,000 7,000 16,000


Process Chamber

ProcessChamberWall

CryopanelArray

ControlModule

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum PumpsVacuum Pumps

Pumping System RangesPumping System Ranges

1010-10-10 1010-9-9 1010-8-8 1010-7-7 1010-6-6 1010-5-5 1010-4-4 1010-3-3 1010-2 -2 760760

CryopumpCryopump

Oil Diffusion Pump with Cold TrapOil Diffusion Pump with Cold Trap

Turbomolecular backed with 2 Stage Mechanical PumpTurbomolecular backed with 2 Stage Mechanical Pump

MechanicalMechanical

Pressure (Torr)

Ultra-High VacuumUltra-High Vacuum High VacuumHigh Vacuum Rough VacuumRough Vacuum

WaterpumpWaterpump

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum Pumps - Vacuum Pumps - CrossoverCrossover

During chamber evacuation,During chamber evacuation,when should the high-vacuum valve be opened?when should the high-vacuum valve be opened?

CrossoverCrossover

VACUUM FUNDAMENTALS: VACUUM FUNDAMENTALS: Vacuum Pumps - Vacuum Pumps - CrossoverCrossover

During chamber evacuation,During chamber evacuation,when should the high-vacuum valve be opened?when should the high-vacuum valve be opened?

This is specified by the manufacturer and depends This is specified by the manufacturer and depends on the individual pump and chamber size.on the individual pump and chamber size.

For cryopumps, the maximum crossover capability is For cryopumps, the maximum crossover capability is specified as the impulsive mass input that causes the specified as the impulsive mass input that causes the

second stage to rise no higher than 20 K.second stage to rise no higher than 20 K.

CrossoverCrossover

CRYOPUMP OPERATIONS: CRYOPUMP OPERATIONS: Vacuum Pumps - Vacuum Pumps - CrossoverCrossover

Crossover Pressure CalculationCrossover Pressure CalculationCrossover value for On-Board 8 = 150 Torr-litersCrossover value for On-Board 8 = 150 Torr-liters

Crossover formula: Crossover formula: Crossover valueCrossover value = P in Torr= P in TorrChamber volumeChamber volume

150 Torr-liters150 Torr-liters = .5 Torr or 500 milliTorr= .5 Torr or 500 milliTorr300 liters300 liters

Benefit: Benefit: Taking advantage of this cryopump feature gives Taking advantage of this cryopump feature gives you faster pumpdown and cleaner vacuum too.you faster pumpdown and cleaner vacuum too.

CRYOPUMPING BASICS:CRYOPUMPING BASICS:

Molecules and TemperatureMolecules and Temperature Capture TheoryCapture Theory Cryopump ConceptCryopump Concept System DesignSystem Design OperationOperation

Topics:Topics:

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Molecules and TemperatureMolecules and Temperature

Molecules in constant motion have kinetic energy.Molecules in constant motion have kinetic energy.

The temperature determinesThe temperature determinestheir average kinetic energy.their average kinetic energy.

The higher the temperature, The higher the temperature, the faster the molecules move.the faster the molecules move.

Molecules and TemperatureMolecules and Temperature


Molecules of gas move fastest.Molecules of gas move fastest.

Molecules of liquids move slower.Molecules of liquids move slower.

Molecules of solids move the least.Molecules of solids move the least.

Molecules and TemperatureMolecules and Temperature


Three scales are used to measure temperature;Three scales are used to measure temperature;

Kelvin (K)Kelvin (K)Celsius or Centigrade (Celsius or Centigrade (ooC)C)

Fahrenheit (Fahrenheit (ooF)F)

The Kelvin (K) temperature scale is used in the The Kelvin (K) temperature scale is used in the science of cryogenics and vacuum technology.science of cryogenics and vacuum technology.

Temperature ScalesTemperature Scales

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Molecules and TemperatureMolecules and TemperatureWater Boils 373 K 100o C 212o F

Room Temperature 293 K 20o C 68o FWater Freezes 273 K 0o C 32o F

Nitrogen Boils 77 K -196o C -320o F

Hydrogen Boils 20 K -253o C -423o FHelium Boils 4.2 K -269o C -452o FAbsolute Zero 0.0 K -273o C -459o F

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Molecules and TemperatureMolecules and TemperatureWater Boils 373 K 100o C 212o F

Room Temperature 293 K 20o C 68o FWater Freezes 273 K 0o C 32o F

Nitrogen Boils 77 K -196o C -320o F

Hydrogen Boils 20 K -253o C -423o FHelium Boils 4.2 K -269o C -452o FAbsolute Zero 0.0 K -273o C -459o F

No Molecular Activity



Topics:Topics:

A chamber could be A chamber could be evacuated if an opening evacuated if an opening and capture mechanism and capture mechanism were provided.were provided.

Creating sufficiently Creating sufficiently cold surfaces, most cold surfaces, most gases could be gases could be captured.captured.

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Capture TheoryCapture Theory


Pumping gases to the extent that gas Pumping gases to the extent that gas molecules, upon contacting a cooled molecules, upon contacting a cooled

surface, lose sufficient energy to form surface, lose sufficient energy to form condensation layers.condensation layers.

CryocondensationCryocondensation

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Capture Theory - Capture Theory - CryocondensationCryocondensation

8080 KK2020 KK4.24.2 KK

Hypothetical surfaces of varying temperatures.Hypothetical surfaces of varying temperatures.


HH22OONN22

ArAr

NeNe

8080 KK2020 KK4.24.2 KK

Most air gases and water vapor are condensed.Most air gases and water vapor are condensed.

HH22


8080 KK2020 KK4.24.2 KK

4.24.2 K is impractical and Helium still boils.K is impractical and Helium still boils.

HH22OONN22

ArAr

NeNeHH22

HeHe


Pumping gases to the extent that gas Pumping gases to the extent that gas molecules, upon contacting a sufficiently molecules, upon contacting a sufficiently

cooled surface, lose enough energy to cooled surface, lose enough energy to accumulate on the surface. accumulate on the surface.

CryoadsorptionCryoadsorption

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Capture Theory - Capture Theory - CryoadsorptionCryoadsorption

A flat cryoadsorbing A flat cryoadsorbing plate retains some plate retains some molecules.molecules.

Flat surface allows Flat surface allows molecules to continue molecules to continue moving.moving.

Cryoadsorbing Plate

EjectedMolecules

Cryopumping Surface

FreeMolecules

Adsorbed Molecules

Surface Collisions


Sieve material, such Sieve material, such as charcoal, provides as charcoal, provides greater surface area and greater surface area and limited apertures.limited apertures.

Large surface area Large surface area capacity;capacity;– 1150-1250 m1150-1250 m22/gm/gm

Activated CharcoalSieve Material

Internal Cavities

LimitedApertures


Increased surface area Increased surface area provides greater capacity.provides greater capacity.

Released molecules Released molecules remain confined.remain confined.

Irregular surface Irregular surface constricts motion.constricts motion.

Cryoadsorption of Cryoadsorption of hydrogen, neon, and hydrogen, neon, and helium accomplished.helium accomplished.

Activated CharcoalFree

Molecules

Adsorbed Molecules

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Capture Theory - Capture Theory - CryoadsorptionCryoadsorptionReplace 4.2Replace 4.2 K surface with cryoadsorbing K surface with cryoadsorbing sieve material attached to <20sieve material attached to <20 K surface.K surface.

8080 KK<20<20 KK

1st Stage1st Stage2nd Stage2nd Stage

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Capture Theory - Capture Theory - CryoadsorptionCryoadsorptionAir gases and water vapor still condensed Air gases and water vapor still condensed

- noncondensible gases captured.- noncondensible gases captured.8080 KK<20<20 KK

HH22OONN22

ArAr

NeNeHH22

HeHe1st Stage1st Stage2nd Stage2nd Stage



Topics:Topics:

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Cryopump ConceptCryopump Concept

Cryopumps are Cryopumps are designed to create designed to create these condensing and these condensing and adsorbing surfaces.adsorbing surfaces.

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Cryopump ConceptCryopump Concept

Cryopumps pump Cryopumps pump different gases at different different gases at different places at different places at different temperatures.temperatures.

Array spacing provides Array spacing provides molecular “Optical Path”molecular “Optical Path”

Necessary temperatures Necessary temperatures are maintained with an are maintained with an integrated control module.integrated control module. Control

Module

H2OO2, N2, Ar

H2, He, Ne



Topics:Topics:

CRYOPUMPING BASICS:CRYOPUMPING BASICS:System DesignSystem Design

Cryopump ComponentsCryopump Components RefrigeratorRefrigerator Helium CircuitHelium Circuit System OverviewSystem Overview

Topics:Topics:

A cryopump is built A cryopump is built around the cold-head.around the cold-head.– Creates temperatures Creates temperatures

needed to condense and needed to condense and adsorb gasesadsorb gases

– Two stages for different Two stages for different temperaturestemperatures

Achieves these Achieves these temperatures by the temperatures by the expansion of helium.expansion of helium.

CRYOPUMPING BASICS:CRYOPUMPING BASICS:System Design - System Design - Cryopump ComponentsCryopump Components

1st Stage:65 K

2nd Stage:12 K


A radiation shield is A radiation shield is attached to the 1st attached to the 1st stage of the cold-head.stage of the cold-head.– Copper for conductivityCopper for conductivity– Nickel plating for Nickel plating for

protectionprotection The vacuum vessel The vacuum vessel

isolates the cryopump.isolates the cryopump. The inlet flange attaches The inlet flange attaches

to the chamber. to the chamber.

RadiationShield

VacuumVessel

Flange


The 1st stage (65 K) The 1st stage (65 K) array is attached to the array is attached to the radiation shield.radiation shield.– Condenses water vaporCondenses water vapor

A series of arrays with A series of arrays with charcoal are attached charcoal are attached to the 2nd stage (12 K) to the 2nd stage (12 K) of the cold-head.of the cold-head.– Condenses OCondenses O22, N, N22, Ar, Ar– Adsorbs HAdsorbs H22, He, Ne, He, Ne

12 K Arraysw/ Charcoal

65 K Array


Both the 1st and 2nd Both the 1st and 2nd stages have an attached stages have an attached heater and temperature heater and temperature sensor to maintain sensor to maintain optimum control and optimum control and operation of the operation of the pumping process.pumping process.

HeatersTemperatureSensors


Cryopump functions Cryopump functions are monitored and are monitored and controlled by the control controlled by the control module interfaced to the module interfaced to the sensors and heaters.sensors and heaters.

ControlModule


Cryopump functions Cryopump functions are monitored and are monitored and controlled by the controlled by the control module control module interfaced to the interfaced to the sensors and heaters.sensors and heaters.– Enhanced performanceEnhanced performance– CommunicationsCommunications– DiagnosticsDiagnostics

CRYOPUMPINGCRYOPUMPING

How is it Done?How is it Done?


Cryopump Components Cryopump Components RefrigeratorRefrigerator Helium CircuitHelium Circuit System OverviewSystem Overview

Topics:Topics:

Primary DisplacerPrimary Displacer Stainless housingStainless housing Brass screen for Brass screen for

thermal massthermal mass Phenolic casingPhenolic casing Helium inlet and Helium inlet and

exhaust exhaust

CRYOPUMPING BASICS:CRYOPUMPING BASICS:System Design - System Design - RefrigeratorRefrigerator

DisplacerHousing

Exhaust Valve

Seal

BrassScreen

Inlet Valve

Cycle begins with Cycle begins with displacer at TDC.displacer at TDC.


Top-Dead Center (TDC)

Cycle Begins with Cycle Begins with displacer at TDC.displacer at TDC.

Inlet valve opens.Inlet valve opens. Displacer moves Displacer moves

downward.downward.


Cycle begins with Cycle begins with displacer at TDC.displacer at TDC.

Inlet valve opens.Inlet valve opens. Displacer moves Displacer moves

downward.downward. Helium fills void.Helium fills void.


At BDC, inlet valve At BDC, inlet valve closes.closes.

Exhaust valve opens.Exhaust valve opens. Displacer moves Displacer moves

upward.upward. Gas expands and cools.Gas expands and cools.


Bottom-DeadCenter(BDC)


Gas flows down through Gas flows down through displacer matrix displacer matrix removing heat.removing heat.

Gas exits through Gas exits through exhaust valve.exhaust valve.


Displacer again at TDC.Displacer again at TDC.

Displacer again at TDC. Displacer again at TDC. Remaining gas exits.Remaining gas exits. Exhaust valve closes. Exhaust valve closes. Cycle repeats at 72 rpm.Cycle repeats at 72 rpm.



After each cycle the After each cycle the displacer matrix (thermal displacer matrix (thermal

mass) is colder ...mass) is colder ...

... pre-cooling the ... pre-cooling the incoming helium incoming helium BEFOREBEFORE

expansion.expansion.

Secondary DisplacerSecondary Displacer Second stage Second stage

attached to top of attached to top of primary displacer primary displacer allows even lower allows even lower temperatures. temperatures.

Lead shot for Lead shot for thermal mass.thermal mass.

Phenolic casing.Phenolic casing.


DisplacerHousing

Exhaust Valve

Seal

BrassScreen

Inlet Valve

Seal

LeadShot

Cycle begins with both Cycle begins with both displacers at TDC.displacers at TDC.


Top-DeadCenter(TDC)


Inlet valve opens.Inlet valve opens. Displacers move Displacers move

downward.downward.



Inlet valve opens.Inlet valve opens. Displacers move Displacers move

downward.downward. Helium fills void above Helium fills void above

primary displacer and primary displacer and passes through passes through secondary displacer secondary displacer to fill second void.to fill second void.


At BDC, inlet valve At BDC, inlet valve closes.closes.

Gas has expanded in Gas has expanded in both voids and cools.both voids and cools.

Exhaust valve opens.Exhaust valve opens. Displacers move Displacers move

upward.upward.


Bottom-DeadCenter(BDC)

Cooled gas flows down Cooled gas flows down through both displacer through both displacer matrices removing heat matrices removing heat from thermal masses.from thermal masses.

Gas exits through Gas exits through exhaust valve.exhaust valve.


Displacers again at TDC.Displacers again at TDC.


Displacers again at TDC. Displacers again at TDC. Remaining gas exits.Remaining gas exits. Exhaust valve closes. Exhaust valve closes. Cycle repeats at 72 rpm.Cycle repeats at 72 rpm.


gmcycle.ppt


After each cycle both After each cycle both displacer matrices displacer matrices

(thermal masses) are (thermal masses) are colder, with the colder, with the

secondary mass colder secondary mass colder than the primary ...than the primary ...

... incoming helium is ... incoming helium is pre-cooled accordingly pre-cooled accordingly

BEFOREBEFORE expansion. expansion.


Cryopump Components Cryopump Components RefrigeratorRefrigerator Helium CircuitHelium Circuit System OverviewSystem Overview

Topics:Topics:

CRYOPUMP OPERATIONSCRYOPUMP OPERATIONSSystem Design System Design - Helium Curcuit:- Helium Curcuit:

CompressorPump

HeatExchanger

Oil MistSeparator

Adsorber

Cryopump


Cryopump ComponentsCryopump Components RefrigeratorRefrigerator Helium CircuitHelium Circuit System OverviewSystem Overview

Topics:Topics:

CRYOPUMPING BASICS:CRYOPUMPING BASICS:System Design - System Design - System OverviewSystem Overview

Cold-HeadPower Cable

Input Power Cable

Cold HeadCryopump

Mounting Flange(Interface to Vacuum Chamber)

ToRoughingSystem

Supply LineReturn LineHelium

CompressorUnit

ControlModule



Topics:Topics:

CRYOPUMPING BASICS:CRYOPUMPING BASICS:OperationOperation

CryocondensationCryocondensation CryoadsorptionCryoadsorption Argon Hang-UpArgon Hang-Up Hydrogen DammingHydrogen Damming CapacitiesCapacities RegenerationRegeneration

Topics:Topics:


Pumping gases by cooling them to point Pumping gases by cooling them to point that they condense, and freeze, on a that they condense, and freeze, on a

surface. A cryopump pumps water and surface. A cryopump pumps water and “air” gases by cryocondensation; the “air” gases by cryocondensation; the

gases form a layer of frost on the gases form a layer of frost on the condensing arrays.condensing arrays.

CryocondensationCryocondensation

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Operation - Operation - CryocondensationCryocondensation

Water molecules Water molecules collide with the cooled collide with the cooled surfaces of the 65 K surfaces of the 65 K first stage array.first stage array.


Water molecules Water molecules collide with the cooled collide with the cooled surfaces of the 65 K surfaces of the 65 K first stage array.first stage array.

Condensation layers Condensation layers form as more of these form as more of these molecules collect.molecules collect.

Other molecules such Other molecules such as oxygen, nitrogen, and as oxygen, nitrogen, and argon pass between the argon pass between the first stage arrays. first stage arrays.



Other molecules such Other molecules such as oxygen, nitrogen, and as oxygen, nitrogen, and argon pass between the argon pass between the first stage arrays. first stage arrays.

By colliding with the By colliding with the 12 K second stage 12 K second stage arrays, these molecules arrays, these molecules also form condensation also form condensation layers.layers.



Topics:Topics:


Pumping gases by cooling them to the point Pumping gases by cooling them to the point that they lose sufficient energy and that they lose sufficient energy and

accumulate on a surface. A cryopump accumulate on a surface. A cryopump pumps H2, He, and Ne in the charcoal pumps H2, He, and Ne in the charcoal adsorbing array by cryoadsorbtion. adsorbing array by cryoadsorbtion.

CryoadsorptionCryoadsorption

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Operation - Operation - CryoadsorptionCryoadsorption

Affixing activated Affixing activated charcoal sieve material charcoal sieve material to the underside of the to the underside of the 12 K second stage 12 K second stage arrays, allows Harrays, allows H22, He, , He, and Ne to be and Ne to be cryoadsorbed.cryoadsorbed.

Array

CharcoalSieve Material


Charcoal sieve material Charcoal sieve material provides large surface provides large surface area capacity for area capacity for adsorption of Hadsorption of H22, He, , He, and Ne .and Ne .– 1150-1250 m1150-1250 m22/gm/gm


Internal Cavities

LimitedApertures


The noncondensible HThe noncondensible H22, , He, and Ne molecules He, and Ne molecules pass between the first pass between the first stage arrays.stage arrays.

Collide with walls and Collide with walls and second stage arrays.second stage arrays.


The noncondensible HThe noncondensible H22, , He, and Ne molecules He, and Ne molecules pass between the first pass between the first stage arrays.stage arrays.

Collide with walls and Collide with walls and second stage arrays.second stage arrays.

Become adsorbed upon Become adsorbed upon contacting the charcoal contacting the charcoal surfaces.surfaces.



Topics:Topics:

During During normal operationnormal operation, , water vapor is condensed water vapor is condensed

on the 65 K first stage on the 65 K first stage array while oxygen, array while oxygen,

nitrogen, and argon are nitrogen, and argon are condensed on the 12 K condensed on the 12 K

second stage array.second stage array.

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Operation - Operation - Argon Hang-UpArgon Hang-Up

12 KArray

65 KArray


<65 K Argon Hang-Up can Argon Hang-Up can occur if the first stage occur if the first stage gets too cold.gets too cold.


<65 K Argon Hang-Up can Argon Hang-Up can occur if the first stage occur if the first stage gets too cold.gets too cold.

Results in argon being Results in argon being condensed (pumped) on condensed (pumped) on the first stage.the first stage.


Argon Hang-Up can Argon Hang-Up can occur if the first stage occur if the first stage gets too cold.gets too cold.

Results in argon being Results in argon being condensed (pumped) on condensed (pumped) on the first stage.the first stage.

Where it stays until Where it stays until lower partial pressures lower partial pressures are reached.are reached.

<65 K

1010-10 -10 1010-7 -7 1010-4 -4 1010-3 -3

Water 130K 153K 185K 198.5KWater 130K 153K 185K 198.5KArgon 23.7K 28.6K 35.9K 39.2KArgon 23.7K 28.6K 35.9K 39.2K



Then, the equilibrium Then, the equilibrium pressure is reached.pressure is reached.– Argon liberatesArgon liberates– Pumpdown slowsPumpdown slows– Causes “False Full” Causes “False Full”

conditioncondition

65 K


Argon liberates until it Argon liberates until it is repumped onto the is repumped onto the second stage where it second stage where it should have been should have been pumped.pumped.

65 K


Argon Hang-Up can be Argon Hang-Up can be avoided with the control avoided with the control module interfaced to the module interfaced to the first stage sensor and first stage sensor and heater. heater. – Monitors and controls Monitors and controls

temperaturetemperature– Prevents a “Too Cold” Prevents a “Too Cold”

conditioncondition

Heater

ControlModule

Temperature

Sensor

Constant65 K



Topics:Topics:

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Operation - Operation - Hydrogen DammingHydrogen Damming

During During normal operationnormal operation, , hydrogen, helium, and hydrogen, helium, and neon are cryoadsorbed neon are cryoadsorbed by the charcoal sieve by the charcoal sieve material fixed to the material fixed to the

underside of the 12 K underside of the 12 K second stage array.second stage array.


Array


Gas molecules adsorb Gas molecules adsorb on the large surface on the large surface area capacity of the area capacity of the sieve material.sieve material.– 1150-1250 m1150-1250 m22/gm/gm

Active molecules are Active molecules are confined within the confined within the internal cavities by the internal cavities by the limited apertures.limited apertures.


Internal Cavities

LimitedApertures


Hydrogen Damming can Hydrogen Damming can occur when the occur when the temperature of the temperature of the second stage falls second stage falls below 12 K.below 12 K.– Hydrogen continues to Hydrogen continues to

be adsorbedbe adsorbed– Less active after colliding Less active after colliding

with outer sieve surfaces with outer sieve surfaces

Array (and Charcoal)< 12 K

Molecules build-up on Molecules build-up on outer surfaces.outer surfaces.– Apertures blockApertures block– Capacity unusedCapacity unused– Pumping speed slowsPumping speed slows



UnusedSurfaces

Molecules build-up on Molecules build-up on outer surfaces.outer surfaces.– Apertures blockApertures block– Capacity unusedCapacity unused– Pumping speed slowsPumping speed slows

Continued movement of Continued movement of free molecules leads to free molecules leads to higher Hhigher H2 2 partial partial pressure.pressure.



FreeMolecules


Hydrogen Damming can Hydrogen Damming can be avoided with the be avoided with the control module control module controlling the second controlling the second stage temperature. stage temperature. – Monitors and controls Monitors and controls

temperaturetemperature– Warms array to 14 K Warms array to 14 K – Redistributes HRedistributes H22

molecules molecules

Heater

ControlModule

Temperature

Sensor

Warmed to14 K

Molecules retain greater Molecules retain greater mobility and move into mobility and move into the sieve material.the sieve material.– Apertures clearApertures clear– Full capacity restoredFull capacity restored


Array (and Charcoal)at 14 K

Central processor Central processor controls and monitors controls and monitors second stage back at second stage back at 1212 - 14 K temperature.- 14 K temperature.– Efficient Hydrogen Efficient Hydrogen

pumping resumespumping resumes– HH22 partial pressure partial pressure

reducedreduced


Array (and Charcoal)cooled to 12-14 K



Topics:Topics:

Gas Collected = Pressure x Speed x TimeGas Collected = Pressure x Speed x Time

Gas Capacity (at STP)Water VaporWater Vapor 1000 liters 1000 liters (gas)(gas)

1 liter (ice)1 liter (ice)

Nitrogen & Argon Nitrogen & Argon 1000 liters 1000 liters (gas)(gas)

1 liter (ice)1 liter (ice)

HydrogenHydrogen 17 liters (gas) 17 liters (gas)

Typical Capacity - Typical Capacity - 6”ANSI Flange6”ANSI Flange

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Operation - Operation - CapacitiesCapacities



Topics:Topics:


The objective of regenerating a cryopump is to The objective of regenerating a cryopump is to remove the captured gases from the pump and remove the captured gases from the pump and

restore its pumping capacity.restore its pumping capacity.

RegenerationRegeneration

Whenever your process system is down is an Whenever your process system is down is an opportunity to regen your cryo without opportunity to regen your cryo without

affecting your process up-time!affecting your process up-time!

When should cryopumps be regened?When should cryopumps be regened?

CRYOPUMPING BASICS:CRYOPUMPING BASICS:Operation - Operation - RegenerationRegeneration

Manual Regeneration and PurgingManual Regeneration and PurgingCryo-Torr RegenerationCryo-Torr Regeneration

Processor Controlled Full RegenerationProcessor Controlled Full RegenerationProcessor Controlled FastRegenProcessor Controlled FastRegen


Manual RegenerationManual Regeneration– Close high vacuum valveClose high vacuum valve– Turn cryopump offTurn cryopump off

High Vacuum Valve

Pump Off


Manual RegenerationManual Regeneration– Close high vacuum valveClose high vacuum valve– Turn cryopump offTurn cryopump off– Wait until pump gets to Wait until pump gets to

room temperature - room temperature - captured gases evolvecaptured gases evolve




– Rough-Out to between Rough-Out to between 50-75 milliTorr50-75 milliTorr

Roughing Line




– Rough-Out to between Rough-Out to between 50-75 milliTorr50-75 milliTorr

– Turn cryopump onTurn cryopump on– Cool to 20 KCool to 20 K

Pump On


But, are the adsorbent But, are the adsorbent pumping surfaces really pumping surfaces really

clean ?clean ?


Array




When captured gases evolve from When captured gases evolve from the adsorbent and condensing the adsorbent and condensing pumping surfaces, molecules pumping surfaces, molecules

travel in all directions.travel in all directions.


Of primary concern are Of primary concern are the water vapor the water vapor

molecules evolving off of molecules evolving off of the first stage array and the first stage array and coming in contact with coming in contact with

the charcoal.the charcoal.


Because of their polar Because of their polar characteristics and size, characteristics and size, water molecules easily water molecules easily contaminate adsorption contaminate adsorption surfaces.surfaces.– Increases pump down Increases pump down

timetime– Exposes cryopump to Exposes cryopump to

rough pump oilrough pump oil

Charcoal Sieve Material


A purge tube is used to A purge tube is used to minimize the risk of minimize the risk of water contamination.water contamination.– Installed inside of the Installed inside of the

radiation shieldradiation shield– Allows better control of Allows better control of

regeneration processregeneration process

Purge Tube


Purge tube introduces Purge tube introduces NN22 gas to dilute evolving gas to dilute evolving captured gases.captured gases.– Controls water migrationControls water migration– Charcoal stays cleanerCharcoal stays cleaner– Hydrogen capacity is Hydrogen capacity is

maximizedmaximized


Purge tube introduces Purge tube introduces NN22 gas to dilute evolving gas to dilute evolving captured gases.captured gases.– Controls water migrationControls water migration– Charcoal stays cleanerCharcoal stays cleaner– Hydrogen capacity is Hydrogen capacity is

maximizedmaximized– Rough-Outs are fasterRough-Outs are faster– Rough pump oil exposure Rough pump oil exposure

is minimizedis minimizedRoughing Line


Cryo-Torr RegenerationCryo-Torr Regeneration– Warm-Up and PurgeWarm-Up and Purge

Cryo-Torr RegenerationCryo-Torr Regeneration

TIME (hrs)

TEMP(K) Warm-Up

and Purge

High VacuumValve Closed

Pump OffPurge Tube


Cryo-Torr RegenerationCryo-Torr Regeneration– Warm-Up and PurgeWarm-Up and Purge– Extended PurgeExtended Purge– Rough OutRough Out– Rate-of-Rise (ROR) TestRate-of-Rise (ROR) Test

Roughing Line


TIME (hrs)

TEMP(K) Warm-Up

and Purge

Extended Purge, Rough, & Rate-of-Rise Test


Cryo-Torr RegenerationCryo-Torr Regeneration– Warm-Up and PurgeWarm-Up and Purge– Extended PurgeExtended Purge– Rough OutRough Out– Rate-of-Rise (ROR) TestRate-of-Rise (ROR) Test– Cool DownCool Down


TIME (hrs)

TEMP(K) Warm-Up

and Purge


Cool Down



Typically 5-6 hours cold-to-cold.Typically 5-6 hours cold-to-cold.


TIME (hrs)

TEMP(K) Warm-Up

and Purge


Cool Down

5


Processor-Controlled Processor-Controlled Full RegenerationFull Regeneration– Water vapor removedWater vapor removed– 100% clean charcoal100% clean charcoal– Restore charcoal to Restore charcoal to

full capacityfull capacity

ControlModule


Processor-Controlled Processor-Controlled Full RegenerationFull Regeneration– Warm-Up and PurgeWarm-Up and Purge

Warms to above room temperature.Warms to above room temperature.

Heaters

Temperature

Sensors

ControlModule

On-Board Full RegenerationOn-Board Full Regeneration

TIME (hrs)

TEMP(K)

5

Warm-Upand Purge


Processor-Controlled Processor-Controlled Full RegenerationFull Regeneration– Warm-Up and PurgeWarm-Up and Purge– Extended PurgeExtended Purge– Rough OutRough Out

Heaters

Temperature

Sensors

Closed loop - heaters stay on.Closed loop - heaters stay on.

ControlModule


TIME (hrs)

TEMP(K)

Extended Purge & Rough

5

Warm-Upand Purge


Processor-Controlled Processor-Controlled Full RegenerationFull Regeneration– Warm-Up and PurgeWarm-Up and Purge– Extended PurgeExtended Purge– Rough OutRough Out– Rate-of-Rise (ROR) TestRate-of-Rise (ROR) Test

Temperature

Sensors

ControlModule


TIME (hrs)

TEMP(K)

Extended Purge & Rough Rate-of-Rise Test

5

Warm-Upand Purge


Processor-Controlled Processor-Controlled Full RegenerationFull Regeneration– Cool DownCool Down T

emperature

Sensors

ControlModule

About 2.5 hours cold-to-cold.About 2.5 hours cold-to-cold.On-Board Full RegenerationOn-Board Full Regeneration

TIME (hrs)

TEMP(K)

2.5 - 3

Extended Purge & Rough

Cool Down

5

Warm-Upand Purge

Rate-of-Rise Test


Processor-Controlled Processor-Controlled FastRegenFastRegen– Pump stays runningPump stays running– About 1 hour cold-to-coldAbout 1 hour cold-to-cold– Only regenerates process Only regenerates process

gasesgases– Restores 100% of gas Restores 100% of gas

capacitiescapacitiesControlModule


Processor-Controlled Processor-Controlled FastRegenFastRegen– Second Stage Warm-Up Second Stage Warm-Up

and Purgeand Purge Heater

Temperature

Sensor

ControlModule

On-Board FastRegenOn-Board FastRegen

TIME (hrs)

TEMP(K)

2.5 - 3Warm-Upand Purge 5


Processor-Controlled Processor-Controlled FastRegenFastRegen– Second Stage Warm-Up Second Stage Warm-Up

and Purgeand Purge– Rough, Heat, and Rough, Heat, and

MeasureMeasure

Heater

Temperature

Sensor

ControlModule

On-Board FastRegenOn-Board FastRegen

TIME (hrs)

TEMP(K)

Cool, Rough, Heat, and Measure

52.5 - 3Warm-Upand Purge


Processor-Controlled Processor-Controlled FastRegenFastRegen– Cool DownCool Down– Diagnostic DataDiagnostic Data

Temperature

Sensor

ControlModule

About 1 hour cold-to-cold.About 1 hour cold-to-cold.On-Board FastRegenOn-Board FastRegen

TIME (hrs)

TEMP(K)

2.5 52.5 - 3~1

Cool Down

Cool, Rough, Heat, and Measure

Warm-Upand Purge


Regeneration SummaryRegeneration Summary

TIME (hrs)

TEMP(K)

52.5 - 3~1

Cryo-Torr RegenerationOn-Board Full RegenerationOn-Board FastRegen


Processor-Controlled Processor-Controlled FastRegen Advantages: FastRegen Advantages: – Shorter downtime due to Shorter downtime due to

regenerationsregenerations– More consistent, More consistent,

repetitive regenerationsrepetitive regenerations– Unattended, automaticUnattended, automatic

Heaters

ControlModule

Temperature

Sensors

Advances in End Station Vacuum Advances in End Station Vacuum Management for Ion ImplantersManagement for Ion Implanters

- Ion Implant Optimization Strategy- Ion Implant Optimization Strategy

- Improved Full Regeneration for - Improved Full Regeneration for Ion Implanters Ion Implanters

Ion Implant Optimization Ion Implant Optimization StrategyStrategy

Pumping hydrogen Pumping hydrogen is a critical vacuum requirement is a critical vacuum requirement Hydrogen is a principal gaseous by-Hydrogen is a principal gaseous by-

product of the implant processproduct of the implant process Its evolution raises end station pressure Its evolution raises end station pressure

by an order of magnitudeby an order of magnitude The pressure rise compromises process The pressure rise compromises process

uniformityuniformity Dose holds preserve uniformity, but Dose holds preserve uniformity, but

compromise throughputcompromise throughput

In a High-Current Implanter, the In a High-Current Implanter, the Disk Scans the Wafers ThroughDisk Scans the Wafers Throughthe Ion Beam . . .the Ion Beam . . .

Disk Scan

FixedIon

Beam

As the Disc Scans the Wafers Through the As the Disc Scans the Wafers Through the Ion Beam HIon Beam H2 2 is Released in Proportion to is Released in Proportion to the Length of the Beam’s Path Across the the Length of the Beam’s Path Across the Coated Wafer SurfaceCoated Wafer Surface

A B C D E

H2 PressureDuring

OneScan

Scan PositionApparent Beam Movement

DISK FRONT VIEW

BeamABCDE

High and varying HHigh and varying H22 generation generationrate causes dosimetry errors.rate causes dosimetry errors.

PPMAXMAX

(For (For process process

uniformity uniformity req’t)req’t)

HH22

PressurePressure (P)(P)

TimeTime

upup upup upupdwndwn dwndwn dwndwn

(Scan Motion)(Scan Motion)

Uniformity Out of Spec During This Interval

Dose holds maintain Dose holds maintain uniformityuniformity, , but cause but cause throughputthroughput loss. loss.

PPMAXMAX



HH22


TimeTime

upupdwndwn dwndwn

Dose holds limit H2

pressureBUT . . . the time scale stretches out as disk scanning stops for each hold

Solution: More HSolution: More H22 Pumping Pumping SpeedSpeed

PPMAXMAX



HH22


TimeTime

upup upup upupdwndwn dwndwn dwndwn

• P=Q/S• Constant Q and higher S means P decreases

. . . but H. . . but H2 2 speed falls off speed falls off as the cryopump’s charcoal fills as the cryopump’s charcoal fills up with Hup with H22..

HH22 Liters Accumulated after Regen = H(T) Liters Accumulated after Regen = H(T)H, LitersH, Liters

S(H)S(H)

SpeedSpeed

And, a Cryopump’s HAnd, a Cryopump’s H2 2 Pumping Pumping Speed is Highest right after Speed is Highest right after Regeneration:Regeneration:

When the pump’s charcoal is emptyWhen the pump’s charcoal is empty H2 Capacity is at it’s MaximumH2 Capacity is at it’s Maximum

HH22 Liters Accumulated after Regen = H(T) Liters Accumulated after Regen = H(T)H, LitersH, Liters

S(H)S(H)

SpeedSpeed

To Maximize The Pump’s HTo Maximize The Pump’s H22 Speed, Regenerate As Speed, Regenerate As Frequently As PossibleFrequently As Possible

On-Board On-Board FastRegenFastRegenTM TM During During Source ChangeSource Change

Full Regeneration During Monthly Full Regeneration During Monthly Source PM’sSource PM’s

On-BoardOn-Board® ® FastRegen™ FastRegen™ Control Control First stage regeneration is rarely First stage regeneration is rarely

neededneeded

FastRegen restores air and HFastRegen restores air and H2 2 capacitycapacity The Result: 100% process The Result: 100% process

performance restored in the minimum performance restored in the minimum amount of time - approximately 1 Houramount of time - approximately 1 Hour

Traditionally, User inclination Traditionally, User inclination was to do infrequent regens. . . was to do infrequent regens. . . varying Hvarying H2 2 Speed lead to Speed lead to varying process uniformity varying process uniformity

RegenerationRegeneration

Pump’s Pump’s RatedRatedSpeedSpeed

TimeTime

HH22 Speed Speed

FastRegen during source FastRegen during source changes: Higher, more stable changes: Higher, more stable speed... leading to more stable speed... leading to more stable process uniformityprocess uniformity

TimeTime

HH22 Speed Speed

Pump’s RatedSpeed

Observed Results - Reduced Observed Results - Reduced Dose HoldsDose Holds

AfterAfterBeforeBefore

6-7 Holds6-7 Holds 2 Holds2 Holds

Implanter - Eaton NV-10Implanter - Eaton NV-10Process - 6.5 mA, BFProcess - 6.5 mA, BF2 2 , 65KeV, 65KeV

On-BoardOn-Board® Cryopumps Cryopumps InstalledInstalled

4040

8080

6060

2020

00

MONTHSMONTHS

HoursHoursDownDown One YearOne Year

Observed Results - Improved Observed Results - Improved Implanter AvailabilityImplanter Availability

Pre-Install Experience

Implanter - Eaton NV-10Implanter - Eaton NV-10

Improved Full Regeneration Improved Full Regeneration for Ion Implantationfor Ion Implantation

In “Dirtier” Implant In “Dirtier” Implant Processes . . .Processes . . .

Photoresist by-products load the Photoresist by-products load the cryopump with gummy hydrocarbon cryopump with gummy hydrocarbon residueresidue

Residues outgas when the cryopump Residues outgas when the cryopump warms for full regenerationwarms for full regeneration

In “Dirtier” Implant In “Dirtier” Implant Processes . . .Processes . . .

This increases the required rough time This increases the required rough time and number of repurge cycles. Result: and number of repurge cycles. Result: very long full regensvery long full regens

The effect is The effect is process specificprocess specific::– Build-up rate varies with current and amount Build-up rate varies with current and amount

of resistof resist– Some processes do not display this behavior Some processes do not display this behavior

at allat all

New On-Board Module for Ion New On-Board Module for Ion ImplantersImplanters Higher-temperature warm-upHigher-temperature warm-up

– Faster outgassingFaster outgassing Simultaneous rough/purge (instead of Simultaneous rough/purge (instead of

simple purge)simple purge)– Faster outgassing and faster gas removalFaster outgassing and faster gas removal

Results:Results:– Faster, more consist regenerationsFaster, more consist regenerations– Especially useful in high-current/high-Especially useful in high-current/high-

throughput applicationsthroughput applications

Previous RoutinePrevious Routine

RougRough h

RORROR

310K310K

ATMATM

TemperatureTemperature ( ) ( )

Pressure Pressure ( )( )

PurgPurgee

WarmWarm CoolCool

Purge at ATM PressurePurge at ATM Pressure

New RoutineNew Routine

RougRough h

RORROR

PurgPurgee

WarmWarm CoolCool

Higher TemperatureHigher Temperature

Simultaneous purge and roughSimultaneous purge and rough

310K310K

ATMATM

330K330K

TemperatureTemperature ( ) ( )

PressurePressure ( ) ( )

Field Test ResultsField Test ResultsCustomer 1 2 3 4

Implanter Type 9000 NV-10 9000300XP350D6200 *

NV-10

Process Current 7-12mA 5-8mA 5-17mA* 500uA

4mA

Beam on 100hr/wk 160hr/wk 160hr/wk 120hr/wk

Full RegenTime

Before 5-6 hrs 5 hrs 6hr 5-6 hrs

After 4 hrs 3-4 hrs 3-4 hrs 3-4 hrsPerformingSince Sept 96 Sept 96 Jan 96 May 96

GUTSGUTS

24 Hours a Day24 Hours a Day 7 Days a Week7 Days a Week 365 Days a Year365 Days a Year 1 Hour Response1 Hour Response Answered by a Qualified Answered by a Qualified

Service EngineerService Engineer

On-Board Central ControlOn-Board Central Controlfor Windowsfor WindowsTMTM

PROCESS TOOLPROCESS TOOL


NETWORKED PROCESS TOOLNETWORKED PROCESS TOOL

Network Terminal


Network Terminal

PC with On-Board CentralControl Software for Windows

NETWORKED PROCESS TOOLNETWORKED PROCESS TOOL

Network TerminalNetwork TerminalNetwork TerminalNetwork Terminal


PROCESS TOOLSPROCESS TOOLS

NETWORKED PROCESS TOOLSNETWORKED PROCESS TOOLS


On-Board NetLink


NETWORKED PROCESS TOOLSNETWORKED PROCESS TOOLS


On-Board NetLink PC with On-Board CentralControl Software for Windows


CTI VACUUM SEMINAR WELCOME TO CTI-CRYOGENICS’ VACUUM SEMINAR.

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Transcript of CTI VACUUM SEMINAR WELCOME TO CTI-CRYOGENICS’ VACUUM SEMINAR.