Diamond is an excellent conductor of heat and a poor conductor of
electricity. These properties would make diamond a useful material in
the manufacture of integrated-circuit chips, if it were possible to
produce paper-thin diamond films that could be used as electrical
insulators. Recently, researchers at the Hitachi Research Laboratory in
Japan took some of the first steps toward bringing diamond films into
microelectronics.
The Japanese researchers, reporting their findings at last
month’s International Chemical Congress of Pacific Basin Societies
(PAC CHEM ’84) held in Honolulu, found that microscopic diamonds
are produced when microwaves irradiate a mixture of methane and hydrogen
gas. This treatment forces the gases to decompose to create a plasma of
charged particles. Over a period of hours, tiny diamonds, not more than
30 micrometers in diameter, form on the surface of a solid support, such
as a silicon wafer, set inside the microwave chamber.
The method, however, is far from ready for industrial application.
The ideal conditions for producing diamonds have yet to be identified.
Sometimes, for example, graphite and other types of carbon rather than
diamonds are deposited, and depending on the position of the solid
support, occasionally no deposit forms and silicon is etched away
instead.
