VOID FORMATION AT SILICON-NITRIDE SILICON INTERFACES STUDIED BY VARIABLE-ENERGY POSITRONS

Variable-energy positrons (VEP) were used to study the depth distribution of defects in SiN(x)/Si structures fabricated using ditertiary butyl silane (CONSI 4000) as the silicon precursor in an electron cyclotron resonance plasma chemical vapor deposition system. Films were grown to thickness ranging from 500 to 3500 angstrom at substrate temperatures between room temperature and 400-degrees-C and under various plasma conditions. The VEP results give evidence for differing concentrations of very large open-volume defects at several of the SiN(x)/Si interfaces, confirmed by transmission and scanning electron microscopy. Their presence was correlated with non-reactive organosilicon adsorption on the substrates prior to the thin film deposition.