Touching microlens structure for a pixel sensor and method of fabrication
First Claim
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1. A method for fabricating a microlens structure in a pixel sensor array comprising the steps of:
- a. providing a substrate including a plurality of light sensitive elements adapted to receive light incident to a respective pixel microlens;
b. forming a photoresist material layer over said substrate;
c. patterning said photoresist layer using a first sub-resolution condition to form microlens structure images, said first sub-resolution condition applied in a manner sufficient to form partially connected lens portions at gaps between adjacent microlens structures;
d. developing said photoresist layer to partially form the patterned microlens structures having partially connected lens portions at said gaps;
e. blanket applying a second sub-resolution condition to the partially formed microlens structures; and
,f. flowing said partially formed microlens structures, wherein each microlens structure is webbed such that said microlens structure touches a microlens structure of an adjacent pixel in said array, and such that a curvature of said microlens structure is uniform in all directions to thereby maximize collection of light incident to the microlens structure from all directions.
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Abstract
A structure and method for increasing the sensitivity of pixel sensors by eliminating a gap space formed between adjacent microlens structures in a pixel sensor array. Advantageously, exposure and flowing conditions are such that adjacent microlens structures touch (are webbed) at a horizontal cross-section, yet have a round lens shape in all directions. Particularly, exposure and flowing conditions are such that each touching microlens structure is formed to have a matched uniform radius of curvature at a horizontal cross-section and at a 45 degree cross-sections.
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Citations
12 Claims
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1. A method for fabricating a microlens structure in a pixel sensor array comprising the steps of:
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a. providing a substrate including a plurality of light sensitive elements adapted to receive light incident to a respective pixel microlens; b. forming a photoresist material layer over said substrate; c. patterning said photoresist layer using a first sub-resolution condition to form microlens structure images, said first sub-resolution condition applied in a manner sufficient to form partially connected lens portions at gaps between adjacent microlens structures; d. developing said photoresist layer to partially form the patterned microlens structures having partially connected lens portions at said gaps; e. blanket applying a second sub-resolution condition to the partially formed microlens structures; and
,f. flowing said partially formed microlens structures, wherein each microlens structure is webbed such that said microlens structure touches a microlens structure of an adjacent pixel in said array, and such that a curvature of said microlens structure is uniform in all directions to thereby maximize collection of light incident to the microlens structure from all directions. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of controlling dimensions of a formed microlens structure of a sensor array, said dimensions including a lens size, height and radius of curvature, said method comprising:
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applying first exposure conditions to a photoresist layer patterned to partially form touching microlens structures and developing said layer after first dose exposure; blanket applying second exposure conditions to said partially formed touching microlens structures of said array; and
,flowing said partially formed touching microlens structures of said array at temperatures sufficient to form adjacent microlens structures having a round lens shape in all directions. - View Dependent Claims (9, 10, 11, 12)
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Specification