Interface electronic properties between silicon and silicon nitride deposited by direct photochemical vapor deposition

Interface electronic properties of silicon nitride (SiNx)/crystalline silicon (c-Si) are studied. The interface electronic properties are improved by changing NH3/SiH4 flow ratios (F-NH3/F-SiH4) of a thin SiNx layer (similar or equal to 6 nm in thickness) between c-Si and a thick SiNx layer (similar or equal to 65 nm) deposited with F-NH3/F-SiH4 = 30, where both SiNx layers are formed by direct photochemical vapor deposition (photo-CVD). In the case of F-NH3/F-SiH4 = 120, the minimum interface-trap density and hysteresis obtained from the capacitance-voltage (C-V) characteristics of Al/thick SiNx/thin SiNx/c-Si diodes are 3 x 10(10) cm(-2). eV(-1) and 0.1 V, respectively. In the deposition of thin SiNx, the interface electronic properties are degraded by exposing SixHy or NxHy species to a c-Si surface, where these species are-produced by photodecomposition of NH3/SiH4 gas mixtures. Injected carriers, which cause hysteresis of the C-V characteristics, are discussed in terms of the barrier height for tunneling and the number of interface traps.