30) MESA Type Transistor Performed well also on Silicon
Photo: Chip pattern of silicon mesa type transistor "2SC30" produced
by NEC
In the1960s, all the major Japanese semiconductor manufacturers
rushed to develop silicon semiconductor devices, and it was on February 23
when NEC succeeded in the development of silicon mesa type transistor. The
first prototype of germanium mesa type transistor was developed on February
19, 1960, only four days before silicon mesa type transistor, showing that
NEC continued the development of the silicon and germanium mesa type transistor
in parallel.
Toshio Kurosawa who was one of the leaders of semiconductor device development
at NEC (later, he became a board director of NEC Microcomputers, and others),
wrote in his book titled "Taking up the New Work of Silicon" (Not
for sale), "Thanks to a lot of hard work, we obtained the characteristics
far better than expected. The cut-off frequency was 250MHz in silicon and
700MHz in germanium, which we could never realize with alloy type transistors.
All the people involved in this development toasted to celebrate the memorable
day and to share the joy of the success."
The first prototype of the silicon mesa type transistor was named "V1030"
as the development code, and after repeated improvement trials, the first
product, was registered as "2SC30".
He confessed in the above mentioned book, "But the initial production
plan was like 20 pieces in May, 200 pieces in June, 1,000 pieces in September,
2,000 pieces in October, and so on, in the quantities which we could hardly
call mass production level. The initial production started using the part
of equipment in the laboratory." For reference, the production level
of alloy transistors by the major semiconductor manufacturers at that time
was about six million pieces per month.
Photo: Chip pattern of silicon mesa type transistor "2SC30" produced
by NEC
(By courtesy of Toshio Kurosawa)