Polycrystalline diamond films, single crystal bulk diamonds, and diamond powder were treated in microwave plasma of hydrogen at 1.6 torr under a negative direct-current bias of −150 to −300 V without metal catalyst. It was found that fibrous structures, uniformly elongated along the direction normal to the specimen surface, were formed on the diamond surfaces. Similar experiments for glasslike carbon resulted in conical structures with frizzy fibers at the tops. Transmission electron microscopy measurements indicated that the fibers formed on diamond consisted of randomly oriented diamond nanocrystals with diameters of less than 10 nm, while the conical structures formed on glasslike carbon consisted of graphite nanocrystals. Field emission measurements of the fibrous specimens exhibited better emission efficiency than untreated ones. The field emission electron microscopy of the fibrous glasslike carbon showed a presence of discrete electron emission sites at a density of approximately 10,000 sites/cm2.

Negative-ion implantation is a promising technique for forthcoming ULSI (more than 256 M bits) fabrication and TFT (for color LCD) fabrication, since the surface charging voltage of insulated electrodes or insulators implanted by negative ions is found to saturate within so few as several volts, no breakdown of insulators would be expected without a charge neutralizer in these fabrication processes. Scatter-less negative-ion implantation into powders is also possible. For this purpose an rf-plasma-sputter type heavy negative-ion source was developed, which can deliver several milliamperes of various kinds of negative ion currents such as boron, phosphor, silicon, carbon, copper, oxygen, etc. A medium current negative-ion implanter with a small version of this type of ion source has been developed.

SiO2 films were prepared at a substrate temperature of 100°C by the simultaneous use of a microwave ion source and an ICB system. Transparent and good insulating SiO2 films could be obtained by using 02 gas ions, and they were thermally and chemically stable. Furthermore, both the ionization energy and the incident energy of the 02 gas ions were found to enhance the chemical reaction between SiO and 02 molecules, resulting in the Si02 film formation at a low substrate temperature.

Aluminum oxide (A12O3), nitride(A1N) and silicon nitride(SiN) films were prepared at a low substrate temperature of 100°C. Film resistivity was higher than 5x1013 Ω-cm and the breakdown voltage was greater than 3x10° V/cm. The films deposited on sapphire and silicon substrates were very flat, and were chemically and thermally stable. The A1-O, A1-N and Si-N bonds could be formed effectively by using both ionized clusters and reactive gas ions, and transparent and good quality films were obtained. Through these results, the simultaneous use of an ionized cluster beam (ICB) system and a microwave ion source was found to have a high potential for preparing oxide and nitride films at a low substrate temperature.