Photogate with improved short wavelength response for a CMOS imager

Abstract

A photogate-based photosensor for use in a CMOS imager exhibiting improved short wavelength light response. The photogate is formed of a thin conductive layer about 50 to 3000 Angstroms thick. The conductive layer may be a silicon layer, a layer of indium and/or tin oxide, or may be a stack having an indium and/or tin oxide layer over a silicon layer. The thin conductive layer of the photogate permits a greater amount of short wavelength light to pass through the photogate to reach the photosite in the substrate, and thereby increases the quantum efficiency of the photosensor for short wavelengths of light.

1 . A photogate for use in an imaging device, said photogate comprising: 
 a doped layer formed in a substrate;    a doped region formed in said doped layer; and    a transparent gate formed on at least a portion of said doped region, said transparent gate permitting image light to pass there through and having a thickness within the range of 50 to 3000 Angstroms.    
   
   
       2 - 109 . (canceled)