# US 9,521,304 B2 · Multiple photosites pixel architecture

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- Number: US 9,521,304 B2
- Document ID: US9521304B2
- Status: Granted
- Kind: B2
- Application number: 14/838,456
- Filed: 2015-08-28
- Published: 2016-06-23
- Granted: 2016-12-13
- Earliest claimed: 2014-12-19
- Assignees: STMicroelectronics (Grenoble 2) SAS
- Applicants: Stmicroelectronics (Grenoble 2) SAS
- Inventors: Flavien Hirigoyen; Emilie Huss
- Web page: https://patentgrep.com/patent/US9521304B2

## CPC

- H04N 23/54: Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils
- H04N 25/704: Pixels specially adapted for focusing, e.g. phase difference pixel sets
- H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
- H10F 39/8063: {Microlenses}
- H10F 39/807: {Pixel isolation structures}
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

An image sensor pixel may include an array of four photosites, a transverse isolator wall separating the array in two rows of two photosites, and a longitudinal isolator wall separating the array in two columns of two photosites. Both ends of the longitudinal wall may be set back relative to the edges of the array. First and second conversion nodes may be arranged in the spaces between the longitudinal wall and the edges of the matrix. Each conversion node may be common to two adjacent photosites, and an independent transfer gate may be between each photosite and the corresponding conversion node.

## Claims

### Claim 1

An image sensor pixel comprising:
an array of four photosites;
a transverse isolator wall separating the array in two rows of two photosites;
a longitudinal isolator wall separating the array in two columns of two photosites, wherein ends of the longitudinal isolator wall are set back relative to edges of the array to define a space between each end and a corresponding edge of the array;
first and second conversion nodes positioned in the spaces between the longitudinal isolator wall and the edges of the array, each conversion node being common to two adjacent photosites; and
transfer gates between each photosite and a corresponding conversion node.

### Claim 2 (depends on 1)

The image sensor pixel of claim 1 wherein the transfer gates are located around the conversion nodes.

### Claim 3 (depends on 1)

The image sensor pixel of claim 1 wherein the array of photosites is implemented using CMOS circuitry.

### Claim 4 (depends on 1)

The image sensor pixel of claim 1 wherein the ends of the transverse wall contact respective edges of the array.

### Claim 5 (depends on 1)

The image sensor pixel of claim 1 further comprising a plurality of peripheral isolator walls positioned around the array.

### Claim 6 (depends on 1)

The image sensor pixel of claim 1 further comprising a collimating microlens positioned over the four photosites.

### Claim 7

An image sensor comprising:
an array of photosites;
at least one transverse isolator wall separating the array into a plurality of rows of photosites;
at least one longitudinal isolator wall separating the array in a plurality of columns of two photosites, wherein ends of the at least one longitudinal isolator wall are set back relative to edges of the array to define a space between each end and a corresponding edge of the array;
a respective conversion node positioned in each space between the at least one longitudinal isolator wall and the edges of the array, each conversion node being common to adjacent photosites; and
transfer gates between each photosite and a corresponding conversion node.

### Claim 8 (depends on 7)

The image sensor of claim 7 wherein the transfer gates are located around the conversion nodes.

### Claim 9 (depends on 7)

The image sensor of claim 7 wherein the array of photosites is implemented using CMOS circuitry.

### Claim 10 (depends on 7)

The image sensor of claim 7 wherein the ends of the at least one transverse wall contact respective edges of the array.

### Claim 11 (depends on 7)

The image sensor of claim 7 further comprising a plurality of peripheral isolator walls positioned around the array.

### Claim 12 (depends on 7)

The image sensor of claim 7 further comprising a collimating microlens positioned over the photosites.

### Claim 13

A method for making an image sensor comprising:
forming a transverse isolator wall separating an array of four photosites into two rows of two photosites;
forming a longitudinal isolator wall separating the array into two columns of two photosites, wherein ends of the longitudinal wall are set back relative to edges of the array to define a space between each end and the corresponding edge of the array;
forming first and second conversion nodes positioned in the spaces between the longitudinal isolator wall and the edges of the array, each conversion node being common to two adjacent photosites; and
forming transfer gates between each photosite and a corresponding conversion node.

### Claim 14 (depends on 13)

The method of claim 13 wherein the transfer gates are located around the conversion nodes.

### Claim 15 (depends on 13)

The method of claim 13 wherein the array of photosites is implemented using CMOS circuitry.

### Claim 16 (depends on 13)

The method of claim 13 wherein ends of the transverse wall contact respective edges of the array.

### Claim 17 (depends on 13)

The method of claim 13 further comprising forming a plurality of peripheral isolator walls around the array.

### Claim 18 (depends on 13)

The method of claim 13 further comprising positioning a collimating microlens over the four photosites.