Multi-trench region for accumulation of photo-generated charge in a CMOS imager
AssigneeMicron Technology, Inc.
InventorHoward E. Rhodes
Life of this patent
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Abstract
A multiple-trench photosensor for use in a CMOS imager having an improved charge capacity. The multi-trench photosensor may be either a photogate or photodiode structure. The multi-trench photosensor provides the photosensitive element with an increased surface area compared to a flat photosensor occupying a comparable area on a substrate. The multi-trench photosensor also exhibits a higher charge capacity, improved dynamic range, and a better signal-to-noise ratio. Also disclosed are processes for forming the multi-trench photosensor.
Claims44
A photosensor for use in an imaging device, said photosensor comprising:
- a doped layer of a first conductivity type formed in a substrate;
- a plurality of trenches formed in said doped layer to define a photosensitive area, each of said plurality of trenches having sidewalls and a bottom;
- a doped region of a second conductivity type formed at the sidewalls and bottom of each of said plurality of trenches;
- and
- an insulating layer formed over said doped region.
A photogate sensor for use in an imaging device, said photogate sensor comprising:
- a doped layer of a first conductivity type formed in a substrate;
- a plurality of trenches formed in said doped layer to define a photosensitive area, each of said plurality of trenches having sidewalls and a bottom;
- a doped region of a second conductivity type formed at the sidewalls and bottom of each of said plurality of trenches;
- an insulating layer formed on substantially all of an upper surface of said doped region;
- and
- a light radiation-transparent electrode formed on substantially all of an upper surface of said insulating layer for gating the collection of charges in said doped region.
Dependencies are inferred from the claim text.