ELECTRICAL-PROPERTIES OF SILICON-NITRIDE FILMS PREPARED BY PHOTO-ASSISTED CHEMICAL-VAPOR-DEPOSITION UNDER CONTROLLED DECOMPOSITION OF AMMONIA

Silicon nitride (SiN(x)) films have been deposited at lower substrate temperatures (less-than-or-equal-to 500-degrees-C) by direct (without Hg-sensitization) photo-chemical vapor deposition (photo-CVD) with a l ow-pressure Hg lamp using SiH4 and NH3. The resistivity was as high as 5 X 10(16) OMEGAcm. The minimum value of interface-trap density in Al /SiN(x)/Si metal-nitride-semiconductor (MNS) diodes was estimated to b e 9 x 10(10) cm-2 eV-1 by a quasi-static capacitance-voltage measureme nt. In contrast to conventional plasma CVD of SiN(x), the formation of intermediate species is controlled by the decomposition of NH3 which is decomposed to a lesser extent in a plasma process, based on analyse s of film structures and transient mass spectroscopy, This effect caus es the properties of SiN(x) to not change in a wide range of NH3/SiH4 gas composition.