METHOD FOR MAKING CMOS IMAGE SENSOR INCLUDING PHOTODIODES WITH OVERLYING SUPERLATTICES TO REDUCE CROSSTALK
First Claim
1. A method for making a CMOS image sensor comprising:
- forming a plurality of laterally adjacent photodiodes on a semiconductor substrate having a first conductivity type byforming a retrograde well extending downward into the substrate from a surface thereof and having a second conductivity type,forming a first well around a periphery of the retrograde well also having the second conductivity type,forming a second well within the retrograde well having the first conductivity type, andforming first and second superlattices respectively overlying each of the first and second wells, each of the first and second superlattices comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions.
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Abstract
A method for making a CMOS image sensor may include forming a plurality of laterally adjacent photodiodes on a semiconductor substrate having a first conductivity types by forming a retrograde well extending downward into the substrate from a surface thereof and having a second conductivity type, forming a first well around a periphery of the retrograde well also having the second conductivity type, and forming a second well within the retrograde well having the first conductivity type. Furthermore, first and second superlattices may be respectively formed overlying each of the first and second wells, with each of the first and second superlattices comprising a plurality of stacked groups of layers, and each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions.
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Citations
20 Claims
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1. A method for making a CMOS image sensor comprising:
forming a plurality of laterally adjacent photodiodes on a semiconductor substrate having a first conductivity type by forming a retrograde well extending downward into the substrate from a surface thereof and having a second conductivity type, forming a first well around a periphery of the retrograde well also having the second conductivity type, forming a second well within the retrograde well having the first conductivity type, and forming first and second superlattices respectively overlying each of the first and second wells, each of the first and second superlattices comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for making a CMOS image sensor comprising:
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forming a plurality of laterally adjacent photodiodes on a semiconductor substrate having a first conductivity type by forming a retrograde well extending downward into the substrate from a surface thereof and having a second conductivity type, forming a first well around a periphery of the retrograde well also having the second conductivity type, forming a second well within the retrograde well having the first conductivity type, and forming first and second superlattices respectively overlying each of the first and second wells, each of the first and second superlattices comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions; forming a respective color lens overlying each of the photodiodes; and forming a respective microlens overlying each of the color lenses. - View Dependent Claims (12, 13, 14)
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15. A method for making a CMOS image sensor comprising:
forming a plurality of laterally adjacent photodiodes on a semiconductor substrate by forming a retrograde well extending downward into the substrate from a surface thereof and having a second conductivity type, forming a first well around a periphery of the retrograde well also having the second conductivity type, forming a second well within the retrograde well having the first conductivity type, and forming first and second superlattices respectively overlying each of the first and second wells, each of the first and second superlattices comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base silicon monolayers defining a base semiconductor portion, and at least one oxygen monolayer constrained within a crystal lattice of adjacent base silicon portions. - View Dependent Claims (16, 17, 18, 19, 20)
Specification