# US 2010/0164039 A1 · Image sensor and method for manufacturing the same

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- Number: US 2010/0164039 A1
- Document ID: US20100164039A1
- Status: Published application
- Kind: A1
- Application number: 12/649,251
- Filed: 2009-12-29
- Published: 2010-07-01
- Earliest claimed: 2008-12-31
- Inventors: Il-Ho Song
- Web page: https://patentgrep.com/patent/US20100164039A1

## CPC

- H10F 39/806: {Optical elements or arrangements associated with the image sensors}
- H10F 39/8067: {Reflectors}
- H10F 39/8053: {Colour filters}
- H10F 39/8063: {Microlenses}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

An image sensor includes a photodiode arranged over a semiconductor substrate, a core layer for an optical waveguide, to allow incident light to move toward the photodiode, the core layer being arranged over the photodiode, a clad layer for the optical waveguide, having a lower refractive index than the core layer to reflect the incident light to the photodiode, the clad layer being arranged over the side core layer, and a dielectric layer arranged over a side of the clad layer. An optical waveguide having a uniform refractive index and a flat light-reflection surface can be formed using semiconductor materials such as InP, InGaAsP, SiO2, SiON and PMMA. Furthermore, the optical waveguide can control a refractive index and thus reduce light loss, and a buffer layer can be simply formed by using a polymer.

## Claims

### Claim 1

An apparatus comprising:
a photodiode arranged over a semiconductor substrate;
a core layer for an optical waveguide, to guide incident light toward the photodiode, the core layer being arranged over the photodiode;
a clad layer for the optical waveguide, having a lower refractive index than a refractive index of the core layer to reflect the incident light to the photodiode, the clad layer being arranged over a side of the core layer; and
a dielectric layer arranged over the side of the clad layer.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the clad layer is made of InP and the core layer is made of InGaAsP.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein the clad layer is made of SiO2 and the core layer is made of SiON.

### Claim 4

An apparatus comprising:
a photodiode arranged over a semiconductor substrate;
a core layer for an optical waveguide, to guide incident light toward the photodiode, the core layer arranged over the photodiode; and
a dielectric layer serving as a clad layer for the optical waveguide, having a refractive index lower than a refractive index of the core layer, to reflect the incident light to the photodiode, the clad layer being arranged over a side of the core layer.

### Claim 5 (depends on 4)

The apparatus of claim 4, wherein the core layer is made of a photosensitive polymer.

### Claim 6 (depends on 5)

The apparatus of claim 5, wherein the core layer is made of poly methyl methacrylate.

### Claim 7 (depends on 4)

The apparatus of claim 4, including:
a buffer layer arranged over the entire surface of the core layer and the dielectric layer;
a color filter array arranged over the buffer layer;
a planarizing layer arranged over the color filter array; and
a microlens arranged over the planarizing layer such that the microlens corresponds to the photodiode.

### Claim 8 (depends on 7)

The apparatus of claim 7, wherein the buffer layer is made of polyethylene.

### Claim 9 (depends on 1)

The apparatus of claim 1, including:
a buffer layer arranged over the entire surface of the core layer and the dielectric layer;
a color filter array arranged over the buffer layer;
a planarizing layer arranged over the color filter array; and
a microlens arranged over the planarizing layer such that the microlens corresponds to the photodiode.

### Claim 10

A method comprising:
forming a photodiode over a semiconductor substrate;
forming a dielectric layer over the semiconductor substrate including the photodiode;
forming a photosensitive film mask over the dielectric layer to expose an optical waveguide region;
etching the dielectric layer using the photosensitive film mask as an etching mask to form an opening to expose the photodiode;
forming a clad layer of the optical waveguide, having a first refractive index, such that the clad layer exposes the top of the photodiode and covers an inner wall of the opening; and
forming a core layer for the optical waveguide, having a second refractive index higher than the first refractive index, over the top of the photodiode and the clad layer.

### Claim 11 (depends on 10)

The method of claim 10, wherein the clad layer is made of InP and the core layer is made of InGaAsP.

### Claim 12 (depends on 10)

The method of claim 10, wherein the clad layer is made of SiO2 and the core layer is made of SiON.

### Claim 13

A method comprising:
forming a photodiode over a semiconductor substrate;
forming a dielectric layer having a first refractive index as a clad layer over the semiconductor substrate including the photodiode;
forming a photosensitive film mask over the dielectric layer to expose an optical waveguide region;
etching the dielectric layer using the photosensitive film mask as an etching mask to form an opening to expose the photodiode; and
filling the opening with a core layer for the optical waveguide, the core layer having a second refractive index higher than the first refractive index.

### Claim 14 (depends on 13)

The method of claim 13, wherein the core layer is made of a photosensitive polymer.

### Claim 15 (depends on 14)

The method of claim 14, wherein the core layer is made of poly methyl methacrylate.

### Claim 16 (depends on 15)

The method of claim 15, including forming a buffer layer over the entire surface of the core layer and the dielectric layer.

### Claim 17 (depends on 16)

The method of claim 16, wherein the buffer layer is made of polyethylene.

### Claim 18 (depends on 16)

The method of claim 16, including:
forming a color filter array over the buffer layer;
forming a planarizing layer over the color filter array; and
forming a microlens over the planarizing layer such that the microlens corresponds to the photodiode.

### Claim 19 (depends on 10)

The method of claim 10, including forming a buffer layer over the entire surface of the core layer and the dielectric layer.

### Claim 20 (depends on 19)

The method of claim 19, including:
forming a color filter array over the buffer layer;
forming a planarizing layer over the color filter array; and
forming a microlens over the planarizing layer such that the microlens corresponds to the photodiode.