Silicon nitride (SiNx) films have been deposited at lower substrate temperatures (500) by direct (without mercury-sensitization) photo-chemical vapor deposition (photo-CVD) using SiH4 and NH3 with a low-pressure mercury lamp. Films deposited at around 350 have a polymeric structure such as (Si(NH)2)n. Films deposited at 500 were close to stoichiometric Si3N4 with a slight amount of hydrogen. The refractive index and the dielectric constant of films deposited at 500 became almost equal to the values of thermally synthesized Si3N4. The resistivity was as high as 51016 Ωcm. The minimum density of interface states in Al/SiNx/Si MIS (metal-insulator-semiconductor) diodes was estimated to be 91010 cm-2eV-1 by a quasi-static capacitance-voltage measurement. For SiNx films deposited at 300, the density of interface states, which was in the order of 1011 cm-2eV-1 as deposited, decreased by a rapid thermal anneal after the deposition. For Al/SiNx/InP MIS diodes, it was 31011 cm-2eV-1 by high-frequency capacitance-voltage measurements. Direct photo-CVD for SiNx films is promising for low-temperature formation of a gate insulator.

Hetero-interface properties of SiO2/4H-SiC on (0001), (11-20), and (03-38) crystal orientations are presented. Epitaxial growth on new crystal orientations, (11-20) and (03-38), is described by comparing with the growth on (0001). Using thermal oxidation with wet oxygen, metal-oxide-SiC (MOS) structure was fabricated. From high-frequency capacitance-voltage characteristics measured at 300 K and 100 K, the interface properties were characterized semi-quantitatively. The interface state density was precisely determined using the conductance method for the MOS structure at 300 K. The new crystal orientations have the lower interface state density near the conduction band edge than (0001). From the characteristics of inversion-type planar MOSFETs, higher channel mobilities were obtained on (03-38) and (11-20) than on (0001). The cause of the difference in the channel mobility is speculated by the difference bond configuration of the three crystal orientations.

Reaction mechanisms in remote plasma CVD (in which plasma excitation of source meterials and film deposition are spatially separated) of SiO2 using activated oxygen species and pure silane (SiH4) were discussed in two destinct cases in a viewpoint of vapor phase reactions. Under high pressures of 50500 mTorr, activated oxygen species and SiH4 could collide with each other many times in the vapor phase. SiH4 was decomposed by chemical reactions due to the collisions generating chemically active precursors such as SiHn (0n3) for film deposition. Nearly stoichiometric films with low hydrogen content were obtained at low temperatures of around 300. Under a pressure of 5 mTorr, the oxygen species and SiH4 could scarcely collide with each other due to a long mean free path resulting no decomposition of SiH4. Insufficient surface reactions between relatively stable SiH4 and activated oxygen species yielded many O-H bonds in deposited films. Electrical properties of the films and the interfaces of SiO2/Si were characterized.