# US 2013/0155283 A1 · Hardened photodiode image sensor

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- Number: US 2013/0155283 A1
- Document ID: US20130155283A1
- Status: Published application
- Kind: A1
- Application number: 13/710,260
- Filed: 2012-12-10
- Published: 2013-06-20
- Earliest claimed: 2011-12-16
- Assignees: STMicroelectronics (Crolles2) SAS; STMicroelectronics S.r.l.
- Inventors: François Roy; Sebastien Place
- Web page: https://patentgrep.com/patent/US20130155283A1

## CPC

- H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
- H04N 5/76: Television signal recording
- H10F 39/8033: {Photosensitive area}
- H10F 39/807: {Pixel isolation structures}
- H10F 71/133: {Providing edge isolation}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

An image sensor including a pixel array, each pixel including, in a substrate of a doped semiconductor material of a first conductivity type, a first doped region of a second conductivity type at the surface of the substrate; an insulating trench surrounding the first region; a second doped region of the first conductivity type, more heavily doped than the substrate, at the surface of the substrate and surrounding the trench; a third doped region of the second conductivity type, forming with the substrate a photodiode junction, extending in depth into the substrate under the first and second regions and being connected to the first region; and a fourth region, more lightly doped than the second and third regions, interposed between the second and third regions and in contact with the first region and/or with the third region.

## Claims

### Claim 1

An image sensor comprising a pixel array, each pixel comprising, in a substrate of a doped semiconductor material of a first conductivity type:
a first doped region of a second conductivity type at the surface of the substrate;
a trench of an insulating material surrounding the first region;
a second doped region of the first conductivity type, more heavily doped than the substrate, at the surface of the substrate and surrounding the trench;
a third doped region of the second conductivity type, forming with the substrate a photodiode junction, extending in depth into the substrate under the first and second regions and being in contact with the first region or connected to the first region by one or several additional regions of the second conductivity type; and
a fourth doped region of the first or second conductivity type, more lightly doped than the second and third regions, interposed between the second and third regions and in contact with the second region and/or with the third region.

### Claim 2 (depends on 1)

The image sensor of claim 1, wherein the ratio of the external lateral perimeter of the trench to the external lateral perimeter of the third region is greater than or equal to 20.

### Claim 3 (depends on 1)

The image sensor of claim 1, wherein the dopant concentration of the fourth region is smaller than or equal to 1016 atoms/cm3.

### Claim 4 (depends on 1)

The image sensor of claim 1, wherein the dopant concentration of the second region is greater than or equal to 1017 atoms/cm3.

### Claim 5 (depends on 1)

The image sensor of claim 1, wherein the dopant concentration of the third region is greater than or equal to 1016 atoms/cm3.

### Claim 6 (depends on 1)

The image sensor of claim 1, wherein the dopant concentration of the substrate is smaller than or equal to 1016 atoms/cm3.

### Claim 7 (depends on 1)

The image sensor of claim 1, wherein the dopant concentration of the first region is greater than the dopant concentration of the third region.

### Claim 8 (depends on 1)

The image sensor of claim 1, comprising a fifth region of the second conductivity type interposed between the first region and the third region, the dopant concentration of the fifth region being smaller than the dopant concentration of the first region and greater than or equal to the dopant concentration of the third region.

### Claim 9 (depends on 1)

A camera comprising the image sensor of claim 1 capable of providing images and a device for storing said images.

### Claim 10

A method for manufacturing an image sensor comprising a pixel array, the method comprising the steps, for each pixel in a substrate of a doped semiconductor material of a first conductivity type, of:
forming a first doped region of a second conductivity type at the surface of the substrate;
forming a trench of an insulating material surrounding the first region;
forming a second doped region of the first conductivity type, more heavily doped than the substrate, at the surface of the substrate and surrounding the trench;
forming a third doped region of the second conductivity type, forming with the substrate a photodiode junction, extending in depth into the substrate under the first and second regions and being in contact with the first region or connected to the first region by one or several regions of the second conductivity type; and
forming a fourth doped region of the first or second conductivity type, more lightly doped than the second and third regions, interposed between the second and third regions and in contact with the second region and/or with the third region.

### Claim 11 (depends on 10)

The manufacturing method of claim 10, wherein the fourth region is doped with the second conductivity type, the third and fourth regions being formed in a single step of implantation of dopants of the second conductivity type.

### Claim 12 (depends on 10)

The manufacturing method of claim 10, further comprising the step of forming of a fifth region of the second conductivity type interposed between the first region and the third region, the dopant concentration of the fifth region being smaller than the dopant concentration of the first region and greater than or equal to the dopant concentration of the third region, the fifth region being obtained by several implantations of dopants of the second conductivity type having different implantation energies.