Japan Semiconductor Innovation 50     (T-5 1970s)

Ultra-Thin Oxide-Nitride Gate Insulator Films (Fujitsu)

Fujitsu demonstrated that silicon-oxide-nitride films, formed by thermal treatment of oxide films in activated nitrogen gas, were superior to silicon thermal oxide films as the gate insulator of MOSFET, first in the world in the latter half of 1970's.
These films were not practically used in this timeframe, but early adoption started in the 90nm generation in which the gate insulator of 2nm and below was used, and it became a standard technology in the 65nm generation. Adoption of High-k films started after the 45nm generation, but the oxide-nitride barrier layer on the silicon interface is regarded to be indispensable. This technology, in which Japan took the initiative, became essential one in high-performance CMOS LSIs in the global semiconductor industry, and will most probably be used in the future generations, too.

A part of 90nm CMOS TEM photo

Reference 1


Fujitsu HP: Fujitsu Sci.Tech.J., vol.39, pp40-51(2003) "Impact of nitrogen profile in gate nitride-oxide"

Photo reference 1
"Electrical properties of 1.5-nm SiON gate-dielectric using radical oxygen and radical nitrogen" IEEE Trans. ED, vol. 49, pp. 1903-1909 (2002)