Pixel cell with high storage capacitance for a CMOS imager
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Accused Products
Abstract
A pixel sensor cell for use in a CMOS imager exhibiting improved storage capacitance. The source follower transistor is formed with a large gate that has an area from about 0.3 μm2 to about 10 μm2. The large size of the source follower gate enables the photocharge collector area to be kept small, thereby permitting use of the pixel cell in dense arrays, and maintaining low leakage levels. Methods for forming the source follower transistor and pixel cell are also disclosed.
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Citations
107 Claims
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1-94. -94. (canceled)
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95. A method of operating a pixel device comprising:
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receiving a plurality of photons at a first doped semiconductor region;
converting at least a portion of the plurality of photons to a plurality of charges in the first doped semiconductor region;
accumulating the plurality of charges in a second doped semiconductor region;
transferring the plurality of charges through an electrically conductive path to a gate of a source follower transistor, the gate having an area of from between about 0.3 μ
m2 to about 25 μ
m2; and
conducting an electrical current through the transistor, the electrical current having a magnitude related to a quantity of the plurality of photons. - View Dependent Claims (96, 97, 98, 99, 100, 101)
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102. A method of forming a photosensitive device comprising:
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forming photosensitive region disposed at a first portion of a semiconductor substrate, the photosensitive region being adapted to receive a flux of photons and responsively generate a plurality of charges;
forming a transistor gate disposed at a second portion of the semiconductor substrate, the transistor gate being adapted to receive and store a portion of the plurality of charges, the transistor gate having an areal dimension of between about 0.3 μ
m2 and about 25 μ
m2; and
forming an electrically conductive path between the photosensitive region and the transistor gate, the electrically conductive path being adapted to share charges between the photosensitive region and the transistor gate. - View Dependent Claims (103, 104, 105, 106, 107)
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Specification