Reactive Plasma Deposited Si‐N Films for MOS‐LSI Passivation

Abstract

Amorphous Si-N films have been synthesized from SiH4 and NH3 by reactive plasma deposition at 275°C in an improved radial flow reactor. With appropriate control of machine and process variables, films have been made with Si/N ratio of 0.75-1.5, density of 2.8-2.2g cm-3, refractive index of 1.9-2.3, stress of 2e9 dynes cm-2 compressive to 5e9 dynes cm-2 tensile, and electrical resistivity at 2e6 V/cm of 1e20-1e4 \Omega-cm. The process is MOS compatible and it produces relatively thick (1 µm) crack-resistant Si-N films (at 450°-500°C) having excellent step coverage and good adhesion to both Au and Al metallization. This paper describes the deposition technique, effect of deposition parameters on various film properties, and the advantages these films offer in silicon integrated circuit technology.