GAERTNER L116S300 STOKES ELLIPSOMETER OPERATING … Gaertn… · The Nf1 is the Film Refractive...

$: GAERTNER L116S300 STOKES ELLIPSOMETER OPERATING … Gaertn… · The Nf1 is the Film Refractive Index located in the appendix I. If the Nf1 button is highlighted it will not accept$
DOCUMENT: GAERTNER L116S300 STOKES ELLIPSOMETER STANDARD OPERATING PROCEDURE Version: 1.0

GAERTNER L116S300 STOKES ELLIPSOMETER OPERATING MANUAL

Version: 1.0 FEB 2011

UNIVERSITY OF TEXAS AT ARLINGTON


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Nanofabrication Research and Teaching Facility

TABLE OF CONTENTS

1. Introduction……………………………………………………… 3 1.1 Scope of Work………………………………………… 3 1.2 Description…………………………………………….. 3 1.3 Safety………………………………………………….. 3

2. Hardware ..............................…………………………………. 3 3. Requirements…………………………………………………… 4

3.1 Training………………………………………………… 4 3.2 Restrictions……………………………………………. 4 3.3 System Checks……………………………………….. 4

4 Operating Procedure …………………………………………. 7 4.1 System Login………………………………………….. 7 4.2 Equipment Alignment……...…………………………. 8 4.3 Measurement………………………………………….. 11

4.4 2Φ Angle Measurement………………………………. 17 4.5 Shutdown………………………………………………. 17

5 Appendix 5.1 Appendix I Ellipsometry Constant 632.8 nm Laser.. 18


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1 INTRODUCTION

1.1 Scope These procedures apply to the Gaertner L116S300 Stokes Ellipsometer. All maintenance should follow the procedures set forth in the manufacturer’s maintenance and operations manuals. This document is for reference only. Personnel should be trained by authorized staff before operating this equipment.

1.2 Description The Ellipsometer measures by reflecting a polarized Class II 6328ÅHeNe laser beam from the sample surface, 6 inches (150mm) or less, at one of eight available incident angles and determines the change in polarization caused by the sample virtually instantaneously via the Stokes Meter. The Stokes Meter measurement head reads the polarized optical properties through the four detectors then computer analyzes and converts it into a Stokes parameter of the polarization of the reflected light. This information coupled with known film parameters such as the film refractive index entered in the Gaertner Ellipsometer Measurement Program (GEMP) calculates the final results ranging from 0 to 60,000 angstroms for up to 3 layers.

1.3 Safety 1.3.1 This machine is connected to 110 VAC. Be very careful and aware of

electrical hazards. If you encounter any electrical malfunctions, contact NanoFAB staff immediately

1.3.2 This machine uses Class II 632.8 nm HeNe Laser emitting less than 1 milliwatt of low power radiation. Do not stare into the beam or it’s reflection.

1.3.3 This machine has no EMO (Emergency Off), If electrical must be removed from system it must be unplugged.

1.3.4 The stage is capable of movement, take care not to pinch your fingers. 1.3.5 Read any posted NanoFAB Engineering Change Notices (ECN) for any

hardware, process or safety changes before running the tool.

2 HARDWARE

2.1 Class II 632.8nm HeNe Laser

2.2 Stokes Meter

2.3 Stage and Alignment Eyepiece

2.4 Computer and Computer Monitor


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3 REQUIREMENTS

3.1 Training You must be a qualified user on the Gaertner L116S300 Stokes Ellipsometer.

The System can read from eight preset incidence angles of 30, 45, 50, 55, 60, 65, 70, 75 and 80. Transparent films from under one angstrom up to several microns and absorbing films less than 500 angstroms thick can be measured. The surface upon which the film is measured can be a semiconductor, dielectric or metal. The state of polarization of the reflected beam is characterized by Psi, (amplitude ratio) and Delta (phase shift) relative to the incident beam. The film(s) and substrate’s optical properties uniquely determine Psi and Delta such that the software can calculate thickness and refractive index of up to 2 films in a 4 film stack.

3.2 Restrictions 3.2.1 None.

3.3 System checks 3.3.1 Check that the Polarizer Arm and the Analyzer angle of incidence are at

70°.

Fig. 3.3.1 Fig. 3.3.1.a

3.3.1.1 Setting the angle of incidence. a. Grasp the polarizer arm ( but never by the laser), and at the rear of

the arm and loosen the clamp screw about one turn. b. Pull outward on the spring-loaded locator pin next to the clamp

screw, and move the arm to the 70° angle of incidence.

Polarizer Arm Analyzer Arm


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Fig. 3.3.1.1

c. Release the locator pin, and move the arm slowly up or down until the pin seats in the detent on the vertical plate. Tighten the clamp screw. (This accurately sets the angle of incidence)

d. Repeat steps a through c to set the analyzer arm angle of incidence being careful not to apply pressure to the StokesMeter measurement head.

e. Follow steps a to d when setting the angle of incidence at any other detended angle for measurement purposes. Both MUST be set at the same angle.

3.3.2 Check that the Ellipsometer is in the ON position. It MUST warm up for a

minimum of 15 minutes before use.

Fig. 3.3.2 Fig. 3.3.2.a

OFF ON

Black Clamp Screw

Silver Locator Pin

Detent Holes


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3.3.3 Check that the indicator light is on.

Fig. 3.3.3

3.3.4 Ensure the Beam Attenuator is in the OPEN position.

Fig. 3.3.4

3.3.5 Turn on system Computer.

Fig. 3.3.5

4 OPERATING PROCEDURE

ON Button


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4.1 System Login

4.1.1. Login to the system’s computer by clicking on the research icon.

Fig. 4.1.1

4.1.2. When it asks for a password enter the word research in lower case

letters.

Fig. 4.1.2

4.1.3 This will take you to the desk top with icons, click on the “GEMP” icon.

Fig.4.1.3

Research Icon


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4.1.4 When the “GEMP” program opens click on the ellipsometer program.

Fig. 4.1.4

4.1.5 This is the screen as it appears that you will use.

Fig 4.1.5

4.2 Equipment Alignment 4.2.1 Place your sample on the stage. Centered as best as possible.

Fig. 4.2.1


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4.2.2 Look through the eyepiece to adjust tilt on the stage. You will see a thin

cross going vertical and horizontal, you will also see a second thicker cross that looks like a “X”. You will need to align the two crosses to meet in the center by using the sample table tilt alignment screws. The table tilt has to be set FIRST.

Bad Alignment Good Alignment

Fig. 4.2.2 Fig. 4.2.2.a

Fig.4.2.2.b

4.2.3 Now go to the GEMP program and click on the F9 Adjust Sample Table button.

Fig. 4.2.3

Front to Back Tilt Left to Right Tilt


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4.2.4 The sample table height adjustment screen will appear. In this, the table is to high as indicated on the right side of the screen. The power level is not at max as indicated on the left side of the screen.

Fig. 4.2.4

4.2.5 Loosen the sample table clamp screw. Turn the big adjustment wheel

located under the stage to either raise or lower the sample table. Careful as the adjustment is extremely sensitive, a small turn makes a big change on the sample table monitor screen.

Fig. 4.2.5 4.2.6 Monitor the sample table height screen. What you want is the highest

power achievable on the left side of the screen and table height centered on the right side of the screen. Recheck the eyepiece alignment.

Fig. 4.2.6 4.2.7 Lock the clamp screw and close the window by clicking on OK.

Table Clamp Screw Big Adjustment Wheel

Max Power Achieved

Active Power Level

Table Level


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4.3 Measurement

4.3.1 At this point you should have the GEMP measurement screen showing.

Fig. 4.3.1

4.3.2 You should have the 0default.trm loaded unless you are going to use one of the other preset files or you have made one for your own use.

Fig. 4.3.2 4.3.3 Next you should have an estimate of the thickness and enter it in

Thickness 1 space if it will not accept click on the thickness button once so that is not highlighted. System will not accept any input in a area that has a highlighted description button.

Fig 4.3.3

Load File Here


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4.3.4 Ensure you have a Nf1 entry. The Nf1 is the Film Refractive Index located in the appendix I. If the Nf1 button is highlighted it will not accept it, you must click on the button to remove the highlight.

Fig. 4.3.4

4.3.5 If you see the AutoFix Nf1 button on and present this indicates that it will measure and calculate a Nf1, if it is to weak to determine a proper thickness it will then default to the entered value in the Nf1 box. You can remove this and have it measure with the value in the Nf1 box by clicking on it to remove it.

Fig. 4.3.5 4.3.6 On occasion you will need to enter a Kf1. This is a Absorption Refractive

Index used on certain films as indicated in the appendix I.

Fig. 4.3.6


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4.3.7 The Ns and the Ks are substrate values for silicon, Ns of 3.89 and a Ks of .022 should be used unless using another type substate that can be located in appendix I.

Fig. 4.3.7

4.3.8 You will now need to ensure that you click (highlight) any two parameters

that you desire to be measured and calculated. Normally Thickness 1 and AutoFix Nf1, at this point you should push F8 Measure & Calculate. This will give you the calcuated Thickness you require, this is what the majority of you will require on a standard wafer substate found in appendix I.

Fig. 4.3.8 4.3.9 There are six measurement modes available if the above measurement is

not sufficient and they are: 4.3.9.1 Thickness 1- Always uses the entered value of film refractive

index Nf1 to calculate Top Film Thickness 1. This gives the best and most stable film thickness measurement provided the index value is correct. This mode can be used to measure very thin films down to 1 Angstrom as well as near period films. This is the measurement process you have just been through in the illustration above.

4.3.9.2 Thickness 1 & Nf1- Always returns a measured film refractive

index Nf1 no matter how unstable and incorrect. Since the calculation top film Thickness 1 is dependent on this index value it will also be incorrect. This measurement mode is used to find an approximate value of film refractive index and thickness. See Manual for a more thorough details.


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4.3.9.3 Thickness 1, Nf1 & AutoFix Nf1- Calculates Top Film Thickness 1

and automatically measures the film refractive index Nf1 if it is in a good measurement range. If the index value is weak and unstable then it automatically defaults to the entered value and is fixed. The index value is important because its value is used to calculate the optical path or film thickness. See Manual for a more thorough details.

4.3.9.4 Thickness 1 & Thickness 2- Calculates top film Thickness 1 and

the film Thickness 2. All other values are fiixed for this calculation. In this mode Thickness 2 behaves much like the index and becomes unstable and difficult to measure in thinner ranges of thickness.

4.3.9.5 Thickness 1 & Kf1- Calculates the top film Thickness 1 and the

top film absorption Kf1. Since Nf1 is more stable, the Nf1 is fixed and the absorption Kf1 is measured. See Manual for a more thorough details.

4.3.9.6 Substrate- Calculates the real Ns and imaginary part of the

refractive index Ks of a bare substrate. Although the measurement itself is straight forward the results are more complicated because most substrates insluding silicon form a thin native layer of oxide on the surface of the substrate when exposed to air. This offsets the calculated value. In addition surface roughness introduces polarization errors that affect Ks. Use of a “book” value is used for consistancy. If a substrate is transperant then care must be taken so that the light reflected from the bottom surface does not enter the ellipsometer. The bottom surface can be roughened up or placed on a thicker layer to absorb the unwanted bottom reflection. See Manual for a more thorough details.

4.4 2 Φ Angle Measurement 4.4.1 The Two Angle Measurement is used to determine the correct thickness of

thicker or multiorder films. Films that are typically in the 3,000 to 30,000 Å range. There are three refractive index calibration modes:

4.4.1.1 Auto Nf – Calculates the film thickness with computer determined

film refractive indexes. The computer determines whether to base the thickness calculationon a measured value of the index or a fixed (estimated) value or the index. See Manual for a more thorough details.

4.4.1.2 Measure Nf - Forces the measurement of both indexes regardless

of their accuracy. Film thicknesses are then calculated based on these values. Incorrect thickness can result since the underlying index values are not correct.


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4.4.1.3 Fix Nf- Forces the calculationof the film thickness based on fixed values of the refractive index as entered by the user in the Model Setup.

4.4.2 You set up the machine as describe before except once you open the

GEMP icon on the desk top you will not click on the ellipsometer button, you will click on the 2Φ button.

Fig. 4.4.2 4.4.3 This is the screen that will appear.

Fig. 4.4.3

4.4.4 Many of the items you will see are relative to the above procedure such as

Thick 1 is Thickness 1 and Nf1 is the same. The functions are used in the same way, the differences will be explained here. You may save and load models as above they are just located in a different area as shown below. As seen in Fig. 4.4.4 .

Fig. 4.4.4


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4.4.5 First this is a two angle measurement. The normal angles will be 70° and 50° and indicating which will be the first angle of measurement. This will usually be the 70° due to this is what the machine is set at most of the time. These are the two angles you should use unless you have a very indepth knowledge and understanding of the tool and what you want to accomplish. The angles are labled Phi 1 and Phi 2 respectively. As seen in Fig. 4.4.5 .

Fig. 4.4.5 4.4.6 Enter your Thickness and Nf settings for the layer or layers you will be

measuring in the sequence as they are on the sample from the top down. For example the top layer is Thick 1 and the next layer down is Thick 2 with the appropriate Nf’s for each. As seen in Fig. 4.4.6 .

Fig. 4.4.6 4.4.7 Once you have your parameter inserted, you will click on the Measure and

Calculate button as in the previous procedure, but located in a different place. As seen in Fig. 4.4.7 .

Fig. 4.4.7 4.4.8 Once click on the measure and calculate button it will do the first

measurement on the first Phi 1 (usually 70°), once complete it will ask you to move the polarizer and analyzer arm to the next Phi 2 (usually 50°) as


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shown in step 3.3.1 above. Then click on the measure and calclate button again. The results are in the Thick 1 and Thick 2 box as indicated in fig. 4.4.8 .

Fig. 4.4.8 4.5 Shutdown

4.5.1 If you have made any changes to the normal files in either program do not

save them. Save them as Save As in another file. This helps keep the standard normal files in place and allows you to be able to pull up your file at a later time. Saving files in the program is normal windows procedures so I will not go through them here. Any questions refer to the manual at the tool.

4.5.2 Shut down the program by clicking on the RED “X” in the top right of the

program box. Or go to the FILE at the top left and Logoff. Then shut the computer down as normal.

4.5.3 Shut the Beam Attenuator off, opposite position (IN) as indicated in 3.3.4

above. 4.5.4 Turn the key to the Ellipsometer to the Off position as indicated in 3.3.2

above. 4.5.5 Ensure you return the Polarizer and Analyzer arms back to the 70°

position and indicated in 3.3.1 above. This completes the shutdown process.

4.5.6 Ensure you have logged into the log book at the tool. If there are problems

give as precise an answer as you can, or email the owner with more detailed information. This helps to determine problem areas to troubleshoot.


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5.0 Appendix

Appendix I Ellipsometry Constants 632.8 nm Laser Only

Material Symbol N K Aluminum (bulk) A1 1.62 5.44

Aluminum (Polished) 1.5 5.5

Aluminum (Sputtered) 2.26

Aluminum (UHV deposited) 1.43 7.28

Aluminum Carbide A14C3 2.7

Aluminum Oxide (film) A12O3 1.7

Antimony (Bulk) Sb 3.17 4.94

Arsenic Sulfide (crystalline) As2S3 2.53 N/A

Arsenic Sulfide (crystalline) As2S3 2.84 6.2x10-6

Cadmium (Bulk) Cd 1.31 5.31

Cadmium Oxide CdO 2.5

Carbon 2.705 .512 - .04

Chromium (Bulk) Cr 3.4 4.4

Chromium Oxide Cr3O3 2.25

Cobalt (Bulk) Co 2.35 4.4

Cobalt Chromium CoCr 1.83 3.772

Cobalt (Deposited) 3.1

Copper (Bulk) Cu 0.44 3.26

Copper (Evaporator) 0.09 3.39



Cubic Carbon (Diamond) C 2.408

Diamond C 2.42

Gadolinium Aluminum GaA1As 3

Gallium Arsenide GaAs 3.8 - 4 .3 - .6

Gallium Arsenide GaAs 3.746 0.653

Gallium Arsenide GaAs 3.888 0.59

Gelatin 1.516- 1.534 0

Germanium (Bulk) Ge 5.45 0.85

Germanium (Evaporator) 4.7 1.52

Glass Borisilicate 1.51- 1.52

Gold (Bulk) 0.306 3.12


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Material Symbol N K Gold (Eletrol.) 0.31 3.31

Gold (Evaporator) 0.155 3.2

Gold (Sputtered) Au 0.25 3.46

Indium Phosphide InP 3.42

Indium Phosphide InP 3.55 0.0813

Indium Tin Oxide (85% Transperant) 1.83

Lithium Niobate LiNbO3 2.2

Magnesium Flouride MgF2 1.385 0.0704

Melamine Formaldehyde 1.6

Mercury Hg 1.719 4.697

Mercury Oxide HgO 2.4

Nickel (Bulk) Ni 1.89 3.55

Nickel (Bulk) Ni 1.99 3.95

Nickel (Electrol.) 1.53 3.4

Oil Lube 1.36

Paraffin 1.433

Photoresist 1.64

Platinum (bulk) Pt 2.22 4.67

Platinum (Electrol.) 2.48 3.37

Polyamide 1.6

Polysilicon 4.06 0.012

Polysilicon (Amorphus) 4.535-4.06 .236-.012

Polysilicon ( Large Grain P Doped) 3.823 0.028

Praseodymium Oxide Pr2O3 2 Quartz (Fused Silica Silicon Dioxide Glass) 1.457 0

Sapphire (Crystalline) A12O3 1.765

Selenite CaSO42H2O 1.5226

Selenite CaSO42H2O 1.5296

Silicide (Similar to Poly) 4.245 1.368

Silicon (Amorphous) a-Si 4.1 0.213

Silicon Carbide SiC 2 - 2.7

Silicon Dioxide (Srystalline) SiO2 1.522

Silicon Dioxide (Deposited) SiO2 1.43 - 1.45 0

Silicon Dioxide (Grown) SiO2 1.455 - 1.46 0

Silox (Mixture of Saline & Oxygen) 1.44 - 1.45

Silver (Bulk) Ag .240 - 3 2.8 - 4.14


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Material Symbol N K Silver (Evaporator) Ag 0.066 4.02

Tantalum (Bulk) Ta 2.1 2.33

Tantalum Pentoxide Ta2O5 2.1

Thallium Iodine (B) T1l 2.78

Tin Oxide SnO2 2 0.03

Titanium (Evaporator) Ti 3 3.62

Titanium Nitride TiN 1.5 2

Titanium Oxide TiO 2.2

Tungsten (Bulk) W 3.27 3.5

Vanadium (Bulk) Va 3.06 3.21

X-Ray (Substrate) 1.74

X-Ray Film 1.55 0

Zinc Zn 2.4 5.53

Zinc (Eavaporator) Zn 2.3 4.9

Zinc Sulfide (Hexagonal) ZnS-Hex 2.36 N/A

Zinc Sulfide (Hexagonal) ZnS-Hex 2.358 N/A

Ziconium Oxide ZrO2 1.97

GAERTNER L116S300 STOKES ELLIPSOMETER OPERATING … Gaertn… · The Nf1 is the Film Refractive...

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Transcript of GAERTNER L116S300 STOKES ELLIPSOMETER OPERATING … Gaertn… · The Nf1 is the Film Refractive...