After my tunnel diode work,
RCA finally started with silicon transistors, several years behind everyone
else. Silicon requires the use of
photo patterning in order to perform very fine work on the top
surface. This was the beginning of
photo resist which is now used by everybody. So beginning in the early 1960s, we started with building
individual silicon transistors. We
primarily built MOS devices, and then tried to develop high frequency units
and eventually got the frequency up to 800 MHz. We did this by building tetrodes – devices with two
gates. This was identified as the
“3N” series of commercial devices.
These were true tetrodes, with one gate used as a control gate, and
the second gate was used to adjust the impedance. These were very fine devices.
At this same time, we looked
at other types of MOS devices, such as high power devices for use in cable
TV (CATV) and we also looked at high voltage devices which might be used
instead of the remaining vacuum tubes which were still in use at the time.
Then we went into integrated
circuits, complementary MOS technology, using both N-channel and P-channel
on the same chip, which is what is needed to make a good integrated circuit. I was involved pretty heavily in this,
and actually made quite a few trips out to Findlay Ohio (where the RCA factory was) during the
transition to production of some of these devices.
To Ditrick Oral History, Page 5