We report on an accurate validation of a new Monte Carlo three-dimensional model. Simulations up to 1200 Angstrom layer thickness have been carried out for amorphous thin film layers of SiN:H deposited at low temperature (400-650 K) on (100) InP, by vacuum ultraviolet (VUV, similar to 185 nm)-induced chemical vapor deposition (CVD). The computer simulations in the mesoscopic-submicronic range are compared with atomic force microscopy and index of refraction measurements. The reconstituted surface roughness and the voids discrete representations of the bulk are found to be in good agreement with these measurements. Simultaneously at around 450 K (at similar to 175 degrees C), thermal characteristic evolution of the both surface roughness and bulk porosity showed a transition from rough to smooth deposition and from low to high density.