Hello All

I am a student at the Univerisity of Cincinnati. I am trying to grow low
stress silicon nitride with a LPCVD. In order for me to characterize the
film I need to measure the residual stress. I currently have a KLA Tencor
P-10 that was purchased from Ingersol Rand as used equipment. It has a
residual stess applett that uses the radius of curvature of a profiled wafer
and compares the elastic modulus of the substrate and the film thickness to
measure residual stress. I am sure you are all familar with this simple
technique. What I am seeking is a precision wafer locater for this KLA
Tencor P-10 Device. I think this is important because it makes sure the
profiler uses the same reference point for the pre scan of the wafer and the
post deposition scan of the wafer. I have tried to do the scan without this
wafer locater and the measured stress is not accurate18-23GPa average
tensile stress(stoichmetric nitride). There is also 4-5 GPa difference in
the calculated stress for different scans of the same wafer. If anyone has
any input on the large inaccuracy let me know. If you have a precision wafer
locater  I am using a 2" or 50mm (100) wafer with a <110> flat.(The locater
is made specifically for 2" wafers) I think that most people are not using
small 2" wafers anymore and I was hoping someone might have a precision
wafer locater laying around that they could sell me second hand. I called
KLA Tencor but the precision wafer locater is $1500.00. At this point I
don't have the money to buy a new one for this much so this is why I need a
used one.

Reguards
Ahmed Shuja
Center for Microelectronics and MEMS
University of Cincinnati

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