Method of making transparent polysilicon gate for imaging arrays
AssigneeWestinghouse Electric Corp.
InventorsJames Halvis, Nathan Bluzer, Robert R. Shiskowski, Li-Shu Chen
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Abstract
An improved MOS photodetector having polysilicon gate material which is made more transparent to visible light by the addition of up to 50% carbon, and preferably about 10% carbon. The surfaces of the polysilicon-carbon gates are oxidized to form a silicon dioxide dielectric layer, thus eliminating the need to deposit a separate dielectric layer for isolation of adjacent gates in an overlapping gate array. The elimination of a separate dielectric layer permits all gates to be formed directly on the substrate dielectric layer, thus providing a uniform drive voltage requirement across the array.
Claims7
A method of making a transparent polysilicon gate, comprising the steps of:
- forming
- an active photon absorber from a semiconductor substrate;
- forming a gate dielectric layer on said active photon absorber;
- depositing a first layer of polysilicon-carbon over said gate dielectric layer;
- defining a first array of gates by placing a first resist pattern over said first layer of polysilicon-carbon whereby portions of said first layer of polysilicon-carbon are exposed;
- forming said first array of gates by removing said exposed polysilicon-carbon in said first resist pattern;
- removing said first resist pattern;
- forming an insulating layer on said first array of gates;
- depositing a second layer of polysilicon-carbon ever said first array of gates;
- defining a second array of gates by placing a second resist pattern over said second layer of polysilicon-carbon whereby portions of said second layer of polysilicon-carbon are exposed;
- and
- forming said second array of gates by removing said exposed polysilicon-carbon in said second resist pattern.
Dependencies are inferred from the claim text.