Rudolph Ellipsometer AutoEL III, ellipsomter
Picture and Location
This tool is located at A3 on the Lab Map:
The Rudolph Ellipsometer appears in all three equipment groups (clean, semiclean, and gold).
How to Become a User
- Read all material on the SNF website concerning the Rudolph Ellipsometer.
- Contact SNF training contact on the Equipment Summary page.
Single wavelength 6328Å
This procedure will describe how to obtain accurate thickness measurements of various thin films. The ellipsometer is best used on a single light penetrable film such as nitride on a silicon substrate or oxide on gallium arsenide; two layers can be measured on the ellipsometer (you should know the thickness and refractive index of the lower layer). The instrument can give extremely accurate measurements, but the user must know roughly the thickness of the film to be measured, as the calculated results are cyclic.
Initialization (main manual page 6 - 21):
- Turn on the AutoEL AC power with the key lock switch and wait 15 minutes for warm-up.
- If the power is already on: RESET (every 24 hours)
Place a control wafer ( ~1000 Å oxide on silicon) on the stage.
“Align Sample,” (page 6-18)
The spot to be measured needs to be clean and smooth, i.e. doesn’t scatter light.
Adjust sample height to reflect light beam into analyzer entrance aperture.
Use the z-axis and tilt adjustments to center the focusing light: the white circle is in the middle of the black ring.
- Up comp: push it up Cont
- Down comp: push it down Cont
|3.||Measuring Routine (page 4 - 42) speed: slow; accuracy: high||02||Enter|
|4.||Calculating Routine (page 4 - 50)|
|to calculate T and N for one unknown transparent film on Si substrate||10||Enter|
|5.||Printer Format (page 4 – 31), TU, delta, PSI||2||Enter|
|6.||Serial Output Format||0||Enter|
|7.||Enter ID Option||0||Enter|
|8.||Spec Thickness (film thickness in Å) approx.||Enter|
|Pattern (page 4 –14) manual|
|(Don’t use “Auto”, use manual and “Align” between each measurement!)|
|Program (= Prog File #2 above)||01||Enter|
|2.||Position Sample: use joystick, align sample see #4 above||Cont|
- Measure the SiO2 control wafer before measuring "real" samples. The result should be about 1000 angstroms in the very center.
- The PSI result should not be below 20.
N = refractive index
NU = refractive index, upper film
NL = refractive index, lower film
NS = refractive index, substrate
List of refractive indices at wavelength 6328A:
Si = 3.858
SiO2 = 1.46
Si-Nitride = 2.0
Low stress nitride = 2.3
Pt = 2.5 - 2.53
T = thickness
TU = thickness, upper film
TL = thickness, lower film
KS = extinction, substrate
Poly on Quartz:
Calculating Routine: 31 - 33
KS = 0.0
NS = 1.46
Calculating Routine 12 or 13:
NS = 3.823
KS = 0.378
- Wear facemask to protect clean wafers!
- Beam Diameter and Spot Sizes page 3 -19
00 99 Enter
E will printout until:
- Shutdown: ESC
- Clean up around the area.
- Report problems and notify the responsible people of any machine problems.