New pryometer head installed ....

[John Shott]

AG400 fans:

This morning AllWin has installed and calibrated a new pyrometer head on 
the AG4100.  The old one was producing an output of only 200-400 mV at a 
thermocouple wafer reading of 1000 deg C.  The new one is producing an 
output in excess of 1000 mV at the same thermocouple reading.

The thermocouple calibration has been run up to a thermocouple wafer 
temperature of 1195 degrees C, so you should get good temperature 
performance up to process temperatures of 1150 degrees C.
Like most pyrometers, of course, it can't see anything below something 
close to 400 degrees C so if you are running a low process temperature 
of something on the order of 600 degrees C, you probably want to make 
sure that your recipe includes a "warm up" step for a short time at 450 
degrees C before moving up to the "real"process temperature so that they 
system is pre-stabilized a bit.

We have not run full process qualifications with the new pyrometer, but 
will try to do so at our earliest convenience.  However, we are aware 
that some of you are anxious to use the system, so we are releasing it 
for use, pending full process qualification.  If you are using it, 
however, please make sure that you conduct appropriate tests with your 
recipe in advance of committing any real wafers to this tool.  Because 
the pyrometer is at the heart of this system, you should thoroughly test 
if you are planning on using the system in these early 
post-pyrometer-replacement days.

Also, if you are running a nitridation recipe, please contact me in 
advance .... I'd like to be with you so that we can monitor the status 
of the ammonia flow to see if we are getting a shutdown of the excess 
flow switch during high-demand ammonia flow.  There were reports of 
ammonia flow problems that we really haven't been able to investigate 
until the pyrometer problem has been resolved .... so will now begin to 
investigate that in earnest.

Happy processing on the AG4100 .... and please let us know if you 
encounter any problems.

John