Cluster Implants for Advanced Productivity€¦ · Centripetal force is balanced by magnetic force...

1 05/24/05

Cluster Implants for Advanced Productivity

Dr. Leonard RubinAxcelis Technologies

Acknowledgements: Patrick Splinter, Michael Graf

2 05/24/05

Cluster Implant ProductivityOutline

! Productivity Advantages & Challenges of Borane Implantation! Axcelis History of Borane Implantation! Machine Design Considerations! Process Applications, Effects and Results! Summary

3 05/24/05

Boron & Borane Compounds

! Boron (B)

! Boron Difluoride (BF2)

Mass Mass/11Mass Mass/11

11 111 1

49 ~4.549 ~4.5

~120 ~11~120 ~11

~210 ~19~210 ~19

! Decaborane (B10H14)

! Octadecaborane (B18H22)

4 05/24/05

“Big Borane” B10H14 & B18H22Benefits and Motivation

! Can dramatically increase ultra-low energy implant throughput

! Implanter can run at much higher extraction energies

! “Drift” operation only thus no energy contamination caused by deceleration

! Same equivalent boron flux can be delivered with much lower electrical beam current

! Low angular divergence

5 05/24/05

Boranes – Challenges

! Challenges• Machine design considerations

– Achieving broad application space– Design of production capable hardware

• Demonstration of process equivalence

6 05/24/05


! Productivity Advantages & Challenges of Borane Implantation

! Axcelis History of Borane Implantation! Machine Design Considerations! Process Applications, Effects and Results! Summary

7 05/24/05

Decaborane Development History at Axcelis! Axcelis experimented with decaborane in 1995

• R&D efforts suspended due to insufficient temperature control in the delivery system.

! Effort restarted in 1999

! Using Decaborane, equivalent beam current on GSD200/E2 platform• 6.5mA @ 2keV • 3.5mA @ 0.5keV

! Source lasted only 10-20 hours before maintenance required

! Production version not completed due to short source life and machine dedication issue

8 05/24/05

Decaborane Development History at AxcelisSource Technology – Temperature Control 1999! Decaborane production is dependent on arc chamber temperature! Operating temperature is less than decomposition temperature

9 05/24/05

Decaborane Development History at AxcelisSource Technology – Temperature Control 1999

! External temperature control• Circulating coolant loop

around vaporizer and delivery tube maintains temperature equilibrium

! Internal temperature control• Circulating coolant loop

through source body limits upper temperature range

10 05/24/05

Decaborane Development History at Axcelis 1999-2000Summary

! Determined temperature range of decaborane decomposition

! Designed and built a temperature-controlled decaborane ion source

! Observed the dimer of decaborane (B20H28)

! Oral presentation at IIT 2000

11 05/24/05


! Productivity Advantages & Challenges of Borane Implantation! Axcelis History of Borane Implantation

! Machine Design Considerations! Process Applications, Effects and Results! Summary

12 05/24/05

Analyzer Magnet Design

qvBR

mv =2

Basic magnet design:

Centripetal force is balanced by magnetic force

Mass-energy product is a good way to describe how “strong” an analyzer magnet is

2)(BRq

mE ∝

Borane ions have higher mass and are transported at higher energy – this is challenging for standard analyzer magnet systems

13 05/24/05

Selectable Selectable resolving resolving apertureaperture

Transport of B18Existing Tool Configurations – Optics Details

70º,54cm9090GSD200/E2-180

70º,54cmNone90GSD200/E2-90

90º,30cmNone80Ultra

Analyzer Magnet (bend angle, radius)

Acceleration Energy (kV)

Extraction Energy (kV)Tool

14 05/24/05


70º,54cm9090GSD200/E2-180






15 05/24/05


70º,54cm9090GSD200/E2-180






16 05/24/05

Maximum Equivalent Boron Energies – B18

7.24.72.546.99840GSD200/E2-

180

2.50.02.546.99840GSD200/E2-901.50.01.528.56000Ultra

Maximum Total B -

Equivalent Energy (keV)

Maximum B Equivalent

Acceleration (keV)

Maximum B -Equivalent Extraction

(keV)

Maximum Extraction

Energy - B18 (keV)

Maximum Mass x Energy

(keV-AMU)Tool

Fixed by Magnet Design

(Radius and Magnetic Field)

17 05/24/05


7.24.72.546.99840GSD200/E2-

180

2.50.02.546.99840GSD200/E2-901.50.01.528.56000Ultra

Maximum Total B -



Acceleration (keV)


(keV)

Maximum Extraction

Energy - B18 (keV)


(keV-AMU)Tool

= (Mass*Energy)/210

18 05/24/05


7.24.72.546.99840GSD200/E2-

180

2.50.02.546.99840GSD200/E2-901.50.01.528.56000Ultra

Maximum Total B -



Acceleration (keV)


(keV)

Maximum Extraction

Energy - B18 (keV)


(keV-AMU)Tool

= (Max B18 Extraction)*(11/210)

19 05/24/05


7.24.72.546.99840GSD200/E2-

180

2.50.02.546.99840GSD200/E2-901.50.01.528.56000Ultra

Maximum Total B -



Acceleration (keV)


(keV)

Maximum Extraction

Energy - B18 (keV)


(keV-AMU)Tool

= (Max Accel)*(11/210)

20 05/24/05


7.24.72.546.99840GSD200/E2-

180

2.50.02.546.99840GSD200/E2-901.50.01.528.56000Ultra

Maximum Total B -



Acceleration (keV)


(keV)

Maximum Extraction

Energy - B18 (keV)


(keV-AMU)Tool

= (Max Ext) + (Max Accel)

21 05/24/05

Low Energy Beam Propagation –the effects of space charge

Example of beam expansion due to space charge:

2 keV B+ 10 mA

0

1

2

3

4

5

6

0 0.1 0.2 0.3 0.4 0.5

distance along beamline (m)

bea

m s

ize

(no

rmal

ized

)

0 1 2 4

relative space charge

Methods for controlling space charge for low energy transport – Magnetic confinement, beamline plasma’s, PEF’s, etc.

323 mvI

EmI

K ∝∝

Perveance (K) is an important beam transport parameter that determines space charge forces

22 05/24/05

Space charge is significantly improved for Boranes

~ 0.0029~ 0.0090.221Relative space charge for

equivalent dopant flux

4.45

1

BF2+

(49)

~ 19~ 111Ion energy for equivalent

dopant velocity

18101Dopant flux for equivalent

ion current

B18Hx+

(~ 210)

B10Hx+

(~ 120)

B+

(11)

B18 delivers 18:1 B18 delivers 18:1 dopant for given ion dopant for given ion charge charge

23 05/24/05

Space charge is significantly improved for Borane’s



4.45

1

BF2+

(49)


dopant velocity


ion current

B18Hx+

(~ 210)

B10Hx+

(~ 120)

B+

(11)Ion energy 19 times Ion energy 19 times higher higher

24 05/24/05

Space charge is significantly improved for Borane’s



4.45

1

BF2+

(49)


dopant velocity


ion current

B18Hx+

(~ 210)

B10Hx+

(~ 120)

B+

(11)

Space charge Space charge reduced by a factor reduced by a factor of more than 300 of more than 300

25 05/24/05

Reduced space charge with borane molecules results in beam size improvement – experimental evidence

0

0.2

0.4

0.6

0.8

1

-150 -100 -50 0 50 100 150

position (mm)

bea

m c

urr

ent (

rela

tive)

B18

B

Lower space charge can Lower space charge can result in a much narrower result in a much narrower beam profile at the waferbeam profile at the wafer

Results in increased beam Results in increased beam utilization efficiency on utilization efficiency on multimulti--wafer and scanned wafer and scanned platformsplatforms

Axcelis 8250Axcelis 8250

26 05/24/05


! Productivity Advantages & Challenges of Borane Implantation! Axcelis History of Borane Implantation! Machine Design Considerations

! Process Applications, Effects and Results! Summary

27 05/24/05

1.E+11

1.E+12

1.E+13

1.E+14

1.E+15

1.E+16

1.E+17

0.1 1 10 100 1000 10000Energy (keV)

Do

se (

ato

ms/

cm2 )

1011

1012

1013

1014

1015

1016

1017

Noise Isolation

Wells (P,B)

CMOS Retrograde

Wells (P,B,As)

CCD Wells (B)

Threshold Voltage Adjust (As,BF2,B,P,In)

Channel Engineering (As,BF2,P,B,In,Sb)

Anti-punchthrough (As,B,In,Sb)

Latchup/ ESD Protection (B)

Bipolar Buried Subcollector (P,As)

Source/Drain Extension (As,BF2,B)

Source/Drain Contact

(As,BF2,B)

Polysilicon Doping (As,B)

Bonded Wafer Splitting for SOI (H,He)

Preamorphization (Ge,Si)

Potential B10 and B18Applications

≤≤≤≤90nm Dual Poly Gate Doping

≤≤≤≤65nm Extension

28 05/24/05

Ultra Low Energy Extension Device Investigations

! Published• 2004 Renesas/SemEquip @ IIT (B18

+; showed B+ equivalence)• 2002 Agere/Axcelis (B10

+; showed B+ equivalence)• 1997 Fujitsu (B10

+; showed B+ equivalence)

! All indications that big borane will work for extension implants

29 05/24/05

B18H22 Spectrum

! Typical mass spectrum• With mass resolution ~ 15

! Peak B18 current in the range of AMU 200 – 210• Contains contributions ranging

from 10B18H6 to 11B18H22

• Contribution from any B17 or other Bx combinations is typically very small

0

0.2

0.4

0.6

0.8

1

0 50 100 150 200 250 300

AMU

beam

cur

rent

(rel

ativ

e)

2 keV B equivalent spectrum2 keV B equivalent spectrum

30 05/24/05

SemEquip ClusterIon™ Source18 mA equivalent current @ 2 keV on Axcelis Ultra

996.9 µµµµA

31 05/24/05

ClusterIon™ Source Evaluation on Axcelis 8250 –Uniformity & Dose! B18 bare wafer uniformity roughly equivalent to B+ results

• No SEF was used• All beams corrected to better than 0.5% non-uniformity

! Dose matching to Ultra confirmedRs vs Energy

0

100

200

300

400

0.1 1 10

B+ equivalent energy

Rs

mea

n (o

hm

/sq)

Rs8250 RsUltra Rs

Energy (equiv keV)

Ibeam (equiv uA)

Rs uniformity (1 sigma)

9 1178 0.543 1190 0.711 1176 0.99

0.5 1041 1.070.2 536 1.98

Courtesy Dr. Ned Eisner Nov-2004

32 05/24/05

0.2 keV EquivalentBoron SIMS – Comparison with Ultra

! Overall SIMS profile is well-matched to B+ implant

! Large difference in 10B concentrations is expected• Ultra uses enriched BF3

• B18 is isotopically natural (contains 10B and 11B)

B181: 4keV B18+; (7,27) tiltB209: 0.2keV B+ Ultra; (5,1.5) tilt

1.E+16

1.E+17

1.E+18

1.E+19

1.E+20

1.E+21

1.E+22

0 5 10 15 20 25 30

Depth [nm]

Con

cent

ratio

n [a

tom

s/cm

3]

B181--11B: 2.846E+14B209--11B: 3.511E+14B181--10B: 6.438E+13B209--10B: 9.461E+11

1111B : B : 1010B ratio is ~ 4:1B ratio is ~ 4:1

for B18 implantfor B18 implant

33 05/24/05

B202: 20keV B18+R010: 1keV B+ 8250

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

0 10 20 30 40

Depth [nm]

Co

un

trat

e [c

ou

nts

/sec

]

B202: 1HR010: 1H

Hydrogen SIMS

! H SIMS profile with B18

shows small difference from standard B+ implant• Assumption: implanted

hydrogen relatively small compared to hydrogen at the wafer

34 05/24/05


! Productivity Advantages & Challenges of Borane Implantation! Axcelis History of Borane Implantation! Machine Design Considerations! Process Applications, Effects and Results

! Summary

35 05/24/05

Summary

! Significant productivity improvements are possible with Boraneimplantations• Extension Implants• Dual Poly Gate

! Existing machines support generation and transport• But have limits in the maximum energy due to the analyzer magnet

capability• Dedicated machines?

! Process integration is promising• Little measureable difference between borane implants and boron

implants.

Cluster Implants for Advanced Productivity€¦ · Centripetal force is balanced by magnetic force...

Documents

Transcript of Cluster Implants for Advanced Productivity€¦ · Centripetal force is balanced by magnetic force...