US 8,409,904 B2 · Methods for forming anti-reflection structures for CMOS image sensors

Abstract

Protuberances, having vertical and lateral dimensions less than the wavelength range of lights detectable by a photodiode, are formed at an optical interface between two layers having different refractive indices. The protuberances may be formed by employing self-assembling block copolymers that form an array of sublithographic features of a first polymeric block component within a matrix of a second polymeric block component. The pattern of the polymeric block component is transferred into a first optical layer to form an array of nanoscale protuberances. Alternately, conventional lithography may be employed to form protuberances having dimensions less than the wavelength of light. A second optical layer is formed directly on the protuberances of the first optical layer. The interface between the first and second optical layers has a graded refractive index, and provides high transmission of light with little reflection.

Claims28

Dependent claims

A method of forming a semiconductor structure comprising:

forming a photodiode in a semiconductor layer;
forming a transistor on said semiconductor layer, wherein a source of said transistor is of integral construction with said photodiode;
forming an interconnect level dielectric layer embedding a metal line on said semiconductor layer;
forming a dielectric layer directly on said interconnect level dielectric layer;
applying self-assembling block copolymers directly on said dielectric layer;
separating said self-assembling block copolymers into portions including a first polymeric block component and portions including a second polymeric block component;
removing said portions including said second polymeric block component selective to said portions including said first polymeric block component;
and
forming an array of protuberances including a protuberance-containing dielectric portion directly on said interconnect level dielectric layer by etching exposed portions of said dielectric layer employing said portions of said first polymeric block component as an etch mask, wherein an etched portion of said dielectric layer comprises said array of protuberances.

6 more elements

A method of forming a semiconductor structure comprising:

forming a photodiode in a semiconductor layer;
forming a transistor on said semiconductor layer, wherein a source of said transistor is of integral construction with said photodiode;
forming a dielectric layer over said photodiode, wherein said dielectric layer laterally surrounds and overlies a gate electrode of said transistor;
applying self-assembling block copolymers directly on said dielectric layer;
separating said self-assembling block copolymers into portions including a first polymeric block component and portions including a second polymeric block component;
removing said portions including said second polymeric block component selective to said portions including said first polymeric block component;
and
forming an array of protuberances including a protuberance-containing dielectric portion over said photodiode by etching exposed portions of said dielectric layer employing said portions of said first polymeric block component as an etch mask, wherein an etched portion of said dielectric layer comprises said array of protuberances.

5 more elements

Dependencies are inferred from the claim text.

Methods for forming anti-reflection structures for CMOS image sensors

Life of this patent

Methods for forming anti-reflection structures for CMOS image sensors

Life of this patent

Abstract

Claims28