Motoaki Abe

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

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-ICs, in particular, C/MOS-ICs of channel-stopperless structure. SIPOS films are semi-insulating and intrinsically neutral. A double-layer system consisting of 3000 A SIPOS and 6000 A SiO2 films is employed as a replacement of a thick silicon dioxide layer in C/MOS-ICs 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-ICs 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.

A 380H × 488V CCD Imager with Narrow Channel Transfer Gates

When the channel width of an FET becomes of the same order of magnitude as the depth of the gate depletion region, an increase of threshold voltage is observed. This narrow-channel effect has been applied successfully in creating an asymmetric potential well under an electrode for two phase CCD operations. The feasibility of this new structure has been confirmed in a 242 element analog delay line and the application is now extended to a 380H × 488V CCD Imager. In the constructed B/W CCD camera.