>>> 'ellips' problem from dcarl -- Wed Jul  5 09:52:29 1989 <<<

Out of paper - that's all.

>>> 'ellips' problem from hoagland -- Wed Jul  5 11:15:36 1989 <<<

Paper has been restored to the ellipsometer printer.

>>> 'ellips' problem from han -- Wed Jul 19 16:04:26 1989 <<<

The vacuum holder is malfuntioning.  It's hard to lift the wafers even after turning off the toggle valve.

>>> 'ellips' problem from bill -- Tue Jul 25 15:43:32 1989 <<<

The stage height adjustment wheel no longer moves the stage.
The wheel turns freely on it's threaded stem -
rather than move the stem up and down.
The wheel does not seem stripped at all,
but perhaps has lost a lock nut of some kind.

I did not have this problem the last time
I used the ellips, and no one has enabled it since,
but a new ellips program has been loaded into the hp...
I'm just complaining - I wish users would report problems
rather than discover them and leave them unannounced.

>>> 'ellips' problem from hoagland -- Wed Jul 26 10:44:24 1989 <<<

problem:  User reports height adjustment screw on ellipsometer
          stage not working- screw turns but stage height remains
          unchanged.

cause:  Stage was moved completely forward to facilitate removal
        of wafer following measurement.  In this position stage 
        cannot be lowered because stage height adjustment post
        does not clear interior surface of X-Y stages.  During
        normal stage movement stage post moves within inside
        cavity of stages.

solution:  Move stage inward to normal range of measurements-
           about +/- 1 in. of stage center.

Another user reported different measurements across wafer comparing
manual displacement of wafer over stage verses vernier adjustment.
A check of stage level verses position on both axises should no
discernible change, but that individual user will be contacted for
more information.  In the meantime an effort will be made to better 
level the entire ellipsometer chassis.

>>> 'ellips' problem from hoagland -- Wed Jul 26 14:42:42 1989 <<<

During efforts to pinpoint a cause for the recent stage
problem some screws were inadvertently lossened on the adjustment
stem which might have effected the stage orientation.  Proper level
of the stage, to very exact tolerances, is required for accurate
repeatable measurements.  Gaertner will be contacted tomorrow(no
techs in now) to determine if a releveling of the stage is necessary.
If it is, the work can be done in-house and the machine should be
back up by Friday.  In the meantime the ellipsometer is working fine
for all but the thinnest films and still remains usable.

>>> 'ellips' problem from hoagland -- Wed Jul 26 16:09:09 1989 <<<

I spoke with Peter Brown of Gaertner this afternoon and he indicated
that in the worst case our stage level is likely only altered slightly-
with almost no impact on measurements.  Nonetheless, we will still take
the machine downstairs to the machine shop ASAP to verify positioning of
the stages just to be certain.  He also said that for thicknesses of
nitride over oxide in the hundred angstrom range, a measured refractive
index span of .1 to .3 is acceptable and in fact quite good for most
ellipsometers.

>>> 'ellips' problem from voros -- Thu Jul 27 07:56:38 1989 <<<

The ellipsometer has been repaired and it is up for use.
Katalin

>>> 'ellips' problem from moazzami -- Thu Jul 27 11:50:55 1989 <<<

I tried to use the ellipsometer to measure the thickness and refractive
index of thin (<200A) oxide films (both thermal and LTO). I was
using the general recipe.  The measured values were way off of the
expected values: unexpectedly high thicknesses and low refractive indices
(~1.26 rather than 1.46, note that this includes THERMAL oxide on bare silicon).However, for films thicker than 200A, I was able to get reasonable values.
We have been able to get accurate results for films thinner than 200A before
(see Bill Flounders' comments.)
The ellipsometer used to be a valuable instrument.
Please check into this problem.

>>> 'ellips' problem from hoagland -- Fri Jul 28 16:53:14 1989 <<<

Efforts to correct apparent tilt of the sample stage proved ineffective.
Since the tilt is not in fact linear across the entire stage, it appears
more likely the linear bearing raceway for the Y axis was bent recently
when a user cranked the micrometer all the way out to remove a wafer(using
both palms) and pulled against a stop.  Please use 1 hand to turn the
micrometers!! We cannot repair the stage, but a series of measurements will
be taken to find the best X and Y micrometer settings so accurate
readings can be achieved.  This only effects films under 200 angstroms
thick.  

>>> 'ellips' problem from bill -- Mon Aug  7 10:24:00 1989 <<<

HP computer is unable to access the hard disk.

I entered a basic system and the ellips programs to the hp
from the backup floppies -
so the Ellips is UP.

but the hard disk access needs to be restored.

>>> 'ellips' problem from hoagland -- Mon Aug  7 17:15:03 1989 <<<

problem:  User reports PC cannot access hard disk.  
          All efforts to load programs on HD fail.

cause:  Unknown.

solution:  Power off hard disk for 20 seconds and restart.
           PC accesses HD successfully- the ellipsometer is
           up and available for use.

>>> 'ellips' problem from hoagland -- Wed Aug  9 09:13:28 1989 <<<

Bill Flounders has been extremely helpful in characterizing the
very thin film performance of this machine both before and after
recent damage to the sample table.  Based on the refractive index of
a <200 angstrom nitride film, the micrometer settings which yield
the best measurement consistent with previous numbers is;
X-axis : 8 on the left micrometer scale
Y axis : 4 on the outer micrometer scale(towards user)
In all cases the only films affected are those under 200 angstroms.
To take measurements across a sample leave the table stationary and
manipulate your wafer with tweezers.

>>> 'ellips' problem from dcarl -- Thu May 10 18:03:53 1990 <<<

out of paper - all else seems to be fine.

Dan Carl
