| Page Properties | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ||||||||||||||||
Video of How to Operate the Gaertner Ellipsometerwith the new software and hardware installed 11/12/21; |
/wiki/spaces/BNCWiki/pages/6239184
iLab Name: Cleanroom Ellipsometer
iLab Kiosk: BRK Metrology Core
FIC: Shared
Owner: Dan Hosler Rich Harlan
Location: Cleanroom - P M Bay
Maximum Wafer Size: 6"/150 mm
| Table of Content Zone | ||||||||
|---|---|---|---|---|---|---|---|---|
| ||||||||
|
Overview
General Description
The cleanroom Ellipsometer can measure the thickness and refractive index of thin films on reflective substrates, as well as the optical properties of bare substrates.
Specifications
- The stage can handle up to a 6 inch wafer diameterManual tilt alignment and table height using computer table adjust screen
- Light source: HeNe laser, 632.8 nm, 1 mW output.
- Advanced StokesMeter™ determines beam polarization
- Incidence angles: 70° (default), 50°, 30°.
- Maximum sample thickness: 1/2 inch.
- Maximum sample diameter: 5 inch.
- Film thickness range: 0-60,000 Angstroms on substrate (or on 1, 2 or 3 other known sublayers).
- Accuracy: ±3 Angstroms (manufacturer claimed over most of measurement range)
- Repeatability: ±1 Angstrom (manufacturer claimed over most of measurement range)
- Spot size is approximately 1mm by 3mm
- Your substrate must be polished and must not rough to defract diffract the laser
Technology Overview
Ellipsometry measures the thickness of an optically transparent film based on a change in polarization of an incident laser. This change is compared to a model, and values for thickness and refractive index are calculated. The values PSI (psi, Ψ) and DEL (delta, Δ).
The software uses the following abbreviations:
- dThick1: Thickness of film being measured
- Nf: Real value of refractive index for film being measured
- Kf: Imaginary value of refractive index for film being measured
- ω (OMEGA): Thickness period; used for determination of thick film thickness
- Ns: Real value of refractive index for substrate
- Ks: Imaginary value of refractive index for substrate
- Φ (PHI): Angle of incidence
- ψ (PSI): Amplitude ratio as determined by measurement
- Δ (DELTA): Phase difference as determined by measurement
- λ (LAMBDA): Wavelength of incident light; fixed at 632.8 nm for HeNe laser
Sample Requirements and Preparation
Backside must be free of contaminants that may transfer to the stage. The area of measurement should be clean to be measured properly.
Standard Operating Procedure
References
| Expand | ||||||
|---|---|---|---|---|---|---|
| ||||||
This instruction covers the set-up and safe use of the Gaertner Ellipsometer L116A measurement system. The ellipsometer measures the thickness of an optically transparent film based on a change in polarization of an incident laser. This change is compared to a model and returns a calculated thickness and refractive index value. The accuracy of the thickness value can be greatly increased if the known refractive index is entered. The film thickness range is between 0Å and 60,000Å. The sample must have a polished surface free of rough defects that will cause the laser to diffract. 1. SAFETY REQUIREMENTSa. Safety glasses must be worn whenever in the clean room, except when using a microscope or when wearing protective goggles. b. Do NOT look directly into the Helium-Neon laser or at the reflection of the laser from the sample stage as noted on the laser caution label. The laser shutter should remain closed unless a measurement is being taken. 2. EQUIPMENTa. Gaertner Ellipsometer Model L116A i. 6-inch Wafer Stage ii. Light Source: HeNe laser, 632.8nm, 1mW output iii. Stokes Meter iv. CRT Monitor for User Interface
3. TOOL CONFIGURATION
4. CYCLE OF OPERATION
b. Verify the Laser Shutter is closed. The shutter should be slid over the laser opening shown in Figure 1. This will prevent accidental laser exposure. c. Turn on the ellipsometer laser power by rotating the Laser Power (key) Switch (clockwise) shown in Figure1. NOTE: Allow the laser to warm up for 15 minutes to ensure reliable measurements d. Turn on the computer and monitor, if not already on. e. Double click the “GEMP_SP” icon if the Gaertner Ellipsometer Measurement Program (GEMP) isn’t already running. f. Verify the laser shutter is closed before placing sample in the center of the stage. |
Questions & Troubleshooting
Process Library
g. Look through the eyepiece on the front of the ellipsometer (Figure3). The stage pitch must be adjusted so the center of the two “X” images are aligned (Figure2). If the thicker cross is missing, verify the overlay knob (Figure3) is turned full counterclockwise. NOTE: There are 3 knobs that adjust the stage. One pitches the stage left and right, one pitches the stage h. Verify the angle of incident is set to 70° i. Open the Laser Shutter by sliding the lever towards you. j. Click on the “Measurement and Calculation” button at the top of the GEMP screen. k. Click on the “F9 Adjust Sample Table” button or press the F9 key on the keyboard. l. Adjust the stage height up or down (Figure2) to move the bar to the maximum power and the click “OK” m. Press the “Load File” button in the upper right area of the Measurement and Calibration window to select a file or n. Click on the “F8 Measure & Calculate” button or press the F8 key on the keyboard. o. The measured data will be displayed in the “Measured Data” on the lower right area of the Measurement and p. For multiple measurements, press the “F5 Start” button or the F5 button on the keyboard. Click on the F6 Stop q. The “Print Stats” button in the Measurement Statistics window will display the information in then main GEMP window. r. Press the “Return” button in the lower right corner (or the X in the upper right corner) when finished taking measurements s. Close the Laser Shutter t. Turn off the Laser and Lamp Power (key) Switch u. Remove sample from stage. v. Log out of iLab
5. SUPPLEMENTAL DATAa. Definition i. Ns – Refractive index for the substrate ii. Nf – Refractive index for the film iii. Ks – Extinction value of refractive index for substrate iv. WL – Laser wavelength v. N – Refractive index vi. PHI (Φ) – Angle of Incidence vii. POL – Polarization angle viii. PSI (Ψ) – Amplitude ratio as determined by measurement ix. DEL (Δ) – Phase difference as determined by measurement x. DELc (Δc) – Phase difference as calculated xi. Default silicon refractive Index = 3.850 xii. Default film refractive index = 1.460 xiii. Default extinction value of refractive index = -0.0200 xiv. Default laser wavelength = 6328 xv. Default angle of incident =70.00 xvi. Default polarization angle = 45.00 6. STARTUP and SHUTDOWNa. Startup i. Press the power button on the computer box ii. Press the power button on the monitor iii. If the monitor displays “C:\GSC>”, type “menu” and press “ENTER”. b. Shutdown i. At the main menu type “99” and then “ENTER” ii. The computer is now safe to power down |
Questions & Troubleshooting
Process Library