Patent ID: 7723140

Claim:
A method of forming a pixel cell, said method comprising: forming a photosensor for accumulating photo-generated charges in a substrate, wherein the act of forming said photosensor comprises forming a first layer of a first conductivity type over a second layer of a second conductivity type, said first conductivity type being different from said second conductivity type; forming a transistor directly coupled to said photosensor for draining excess charges away from said photosensor to a doped region, wherein an amount of charges being drained away is controlled at least by a position of said first layer of said photosensor relative to a gate of said transistor, said photosensor being formed on a first side of said transistor; forming said doped region on a second side of said transistor opposite to said first side; and forming a transfer transistor coupled to said photosensor for transferring the accumulated photo-generated charges from said photosensor.