ITO transparent gates over Si/sub 3/N/sub 4/ layer for a novel IT-CCD image sensor with reduced VOD structure

Abstract

A newly modified architecture using Indium Tin Oxide (ITO) transparent gates is being tested to increase the photosensitivity of solid state image sensors. Applying it to the newly Inter Line Charge Coupled Devices (IT-CCD) with a reduced Vertical Overflow Drain (VOD) shutter voltage structure over a layer of Si/sub 3/N/sub 4/, its photo-responsivity was increased nearly 60% compared to that of the conventional poly-Si-gates, and about 10-20% to that of the thick/thin backside-illuminated solid state image sensor structures. Eventually its transmittivity, and its Quantum Efficiency (QE) are also improved along the light spectrum. In addition, in the blue/green region of the spectrum, about 5% improvement in the photo-responsivity of the newly reduced VOD IT-CCD image sensor structure could be seen, as well as about 10% improvement in the Infra. Red (IR)-region, compared to its previously used structure using only a layer of Si/sub 3/N/sub 4/ film.