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TriQuint Semiconductor Testimonial
MANUFACTURING OPERATIONS
3625A S.W. Murray Blvd.
Beaverton. Oregon 97005
Phone: (503) 671-0
FAX: (503) 644-9945
 June 2, 1995
Mr. Austin R. Blew
President, Lehighton Electronics
Dear Austin,
I have thought further about our recent conversations about the value of our Lehighton 1310 Contactless Conductivity Probes here at TriQuint. I believe we can
best put a value on the instruments by considering how our fab would run if we didn't have them.
We use our primary 1310 for clearing our front end for use on a daily basis. Every
day, a normal semiinsulating GaAs wafer is sent through our production front end, consisting of wafer prep, cap deposition, blanket FET channel implant and rapid
thermal anneal. The wafer is then tested on the Lehighton using a 35 point map . If average sheet resistance and on-wafer uniformity fall within our SPC limits, the front
end of the process is considered OK and the day's fab runs can be started. Otherwise, the front end is shut down for production and we mobilize to determine the source of the discrepancy and ameliorate it.
Sometimes the front end is indeed shut down by the daily monitor SPC for a variety of reasons. On average, that happens about once per quarter. Depending on the
nature of the problem, we could be down a day or two or as long as a week or more until things are fixed and our daily monitors are back where they should be. The
Lehighton 1310 thus keeps us from starting wafers that would be sub-standard.
If we didn't have a Lehighton, we would get our first sign of trouble at our
in-process test point after Ohmic alloy. That step comes midway in our production processing. All runs in the interim would be affected. Even if we very conservatively
assume we would only lose 10% of our yield from the problem, the lost revenue would be substantial. We estimate we save a minimum of $250K per year by having the Lehighton systems.
In addition to production use, our Lehighton systems are also widely used for rapid process development in implant and anneal and for qualifying potential new
substrate suppliers. For our HEMT production, one instrument is used for incoming inspection of GaAs epi wafers with sheet resistances of 30 kOhm/sq. and higher. In
that case we use the Lehighton system to clear wafers for use.
Any GaAs fab or epi house would benefit from possessing the Lehighton system. We at TriQuint wouldn't part with ours.
Sincerely,
Dr. Martin J. Brophy
Senior Process Engineer for Wafers/Implant/Anneal
TriQuint Semiconductor
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