Semi-Insulating Polycrystalline-Silicon (SIPOS) Films Applied to MOS Integrated Circuits

Abstract

A semi-insulating polycrystalline-silicon (SIPOS) film doped with oxygen atoms is deposited on the surface of silicon substrates by a chemical vapor reaction of silane and nitrous oxide in nitrogen ambient, and has been studied for the surface passivation of MOS-IC's, in particular, C/MOS-IC's of channel-stopperless structure. SIPOS films are semi-insulating and intrinsically neutral. A double-layer system consisting of 3000 Å SIPOS and 6000 Å SiO2 films is employed as a replacement of a thick silicon dioxide layer in C/MOS-IC's of channel-stopperless structure and exhibits excellent field-passivating properties, namely, a small drain-source leakage current, a high drain breakdown voltage, and a high parasitic threshold voltage. Furthermore, the silicon surface passivated by SIPOS films shows high stability under a severe bias-temperature stress. It is concluded that C/MOS-IC's passivated by SIPOS films are not required to have a channelstopper diffusion region and can be operated at high applied voltages, which leads to higher integrating density and higher reliability.