|
|
Oral History – Herb Meisel
(Continued)
|
|
Norm Turner did the
original development engineering. However, when in the early production ,
in the early 60's, there was a lot-to-lot variation in the stability of the
planar oxide on operating life. So production lots, determined by wafers
which were fabbed together, were held until a one week operating life
sample was run and tested. Around that time, Stu Peck and Connie Zierdt of
Western Electric in Allentown wrote a paper on reverse biasing planar
devices at 200C to accelerate failures. I adapted their technique and
demonstrated that I could duplicate the results of the one week operating life
test in 24 hours at 200c with 60V bias (minimal current). This gave a
significant cost and time reduction to the factory. It also was a fast
turnaround test for process changes. About that time, some people at
Carnegie Mellon identified the root cause of the oxide problem as the
sodium ion. It followed that a controlled amount of phosphorus in the oxide
would getter the sodium and the device would be stable! Halleluyah! Working
with Vince Lukach of the reliability group, we were also able to quickly
screen out unstable RF power transistors for the LEM, Lunar Excursion
Module project (which worked well out there).
Having
worked long and hard on various hermetic sealing projects, I was assigned
to a task force in the late 60's to put silicon power devices into plastic
molded packages. Our competitors were starting to do it and some customers
were willing to take the risk for the cost savings.
|
|
|
Oral History – Herb Meisel
(Continued)
|
|
Milt Grimes
and Don Henrikson covered the molding and the mechanical design while and I
covered the device aspects. The overall driving force was Joe Donahue, head
of the semiconductor division. We finally came up with some producible
designs but it took a lot of cut and try cycles til we got there. The
drawing in U.S. Patent # 3,478,420, inventors Milt Grimes, Don Henrikson,
and me show the final designs very clearly. The design shown in Figure 13
proved to be a huge success.
In 1969, I
was assigned the design leader responsibility for power hybrids. We
developed hermetic and plastic versions of a 100 watt amplifier, a 400
ampere switch (for an Air Force contract), and a 5 amp voltage regulator in
a multi-lead TO-3 package.
______________
|
|