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 REQUIREMENTS

a. 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.    EQUIPMENT

a. 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

a. User time must be scheduled through iLab prior to using the system.

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. Place the sample in the center of the stage.

f.  Open the Laser Shutter by sliding the lever towards you.

g. Press “1” and then “Enter” to select the Single Layer non-absorbing (Single point) STDS.EXE option.

h. Press F2 (DISP) to display results to the screen.

i.  Press F1 (FILM) to choose the film program.

j. Verify the angle of incident is set to 70° shown in Figure2.

              NOTE:  This measurement angle is generally already set to 70°, but can be adjusted by releasing the set 
                          screw on the back and lifting the arms.  Lifting by the laser tube arm or stokes 
                          meter arm will cause the system to be misaligned.

k. Press the “F9” key to maximize the signal. The crosshairs should be aligned as shown in Figure3. The

              alignment is performed by adjusting the knurled knobs shown in Figure2.

              NOTE: There are 3 knobs that adjust the stage.  One pitches the stage left and right, one pitches the stage 
                         fore and aft, and one moves the entire stage up and down.

l. Press “E” to exit the alignment screen

m. Press “F5” to measure the film thickness and refractive index.

It should be noted the system is measuring for two unknown values (thickness and refractive index) and may introduce some error in one or both of the values

n. If the refractive index is known, press “F7” to “SETUP” a fixed/known value and the press “F2” to enter the fixed refractive index.

o. Type “1” and “ENTER” to enter the refractive index fixed (Nf) value.

p. Type the fixed refractive index value (i.e. 1.465) and press “ENTER”.

q. Press “F10” to exit the SETUP screen

r. Press “F5” to measure the film thickness with the known/fixed refractive index (Nf).

s. Record the film thickness (THICK). The thickness should be between 1090.1Å and 1095.1Å if measuring the standard (see the control chart).

t. Press “F10” at least two (2) times to access the main menu.

u. Close the Laser Shutter

v. Turn off the Laser Power (key) Switch

w. Remove sample from stage.

x. Log out of iLab

5.    SUPPLEMENTAL DATA

a. 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 SHUTDOWN

a. 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