# US 12,002,837 B2 · Imaging sensor with near-infrared absorber

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- Number: US 12,002,837 B2
- Document ID: US12002837B2
- Status: Granted
- Kind: B2
- Application number: 17/358,326
- Filed: 2021-06-25
- Published: 2022-12-29
- Granted: 2024-06-04
- Earliest claimed: 2021-06-25
- Assignees: Microsoft Technology Licensing, LLC
- Applicants: Microsoft Technology Licensing, LLC
- Inventors: Minseok Oh; Satyadev Hulikal Nagaraja; Cyrus Soli Bamji
- Web page: https://patentgrep.com/patent/US12002837B2

## CPC

- H10F 39/184: {Infrared image sensors}
- H10F 39/8057: {Optical shielding}
- H04N 23/11: for generating image signals from visible and infrared light wavelengths
- H04N 25/633: by using optical black pixels
- H04N 25/671: for non-uniformity detection or correction
- H04N 25/673: by using reference sources
- H04N 25/703: SSIS architectures incorporating pixels for producing signals other than image signals
- H04N 25/771: comprising storage means other than floating diffusion
- H10F 39/8023: {Disposition of the elements in pixels, e.g. smaller elements in the centre of the imager compared to larger elements at the periphery}
- H10F 39/8027: {Geometry of the photosensitive area}
- H10F 39/806: {Optical elements or arrangements associated with the image sensors}
- H10F 39/807: {Pixel isolation structures}
- G01S 7/4863: Detector arrays, e.g. charge-transfer gates
- G01S 17/894: Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar
- H04N 25/704: Pixels specially adapted for focusing, e.g. phase difference pixel sets
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

An example imaging sensor comprises a bulk silicon substrate and a pixel array. The pixel array comprises an active pixel region including an active pixel subarray, an optical black pixel region including an optical black pixel subarray, and an optical black dummy pixel region including an optical black dummy pixel subarray, the optical black dummy pixel region positioned between the active pixel region and the optical black pixel region. A near-infrared absorber is positioned between the active pixel region and the optical black pixel region, the near-infrared absorber comprising a material having a higher near-infrared absorption coefficient than that of silicon.

## Claims

### Claim 1

An imaging sensor, comprising:
a bulk silicon substrate;
a pixel array comprising:
an active pixel region including a subarray of active multi-tap pixels,
an optical black pixel region including a subarray of optical black multi-tap pixels, and
an optical black dummy pixel region including a subarray of optical black dummy pixels, the optical black dummy pixel region positioned between the active pixel region and the optical black pixel region;
a near-infrared absorber positioned between the active pixel region and the optical black pixel region, the near-infrared absorber comprising a material having a higher near-infrared absorption coefficient than that of silicon; and
a controller configured to
supply a clocking signal to integrate light at a first tap of an optical black multi-tap pixel of the subarray of optical black multi-tap pixels to generate a first signal, and to integrate light at a second tap of the optical black multi-tap pixel to generate a second signal; and
apply a dark current correction to an active multi-tap pixel of the subarray of active multi-tap pixels based at least in part on the second signal.

### Claim 2 (depends on 1)

The imaging sensor of claim 1, wherein the near-infrared absorber comprises germanium.

### Claim 3 (depends on 1)

The imaging sensor of claim 1, wherein the near-infrared absorber is positioned between pixels of the optical black dummy pixel subarray and an opaque light shield.

### Claim 4 (depends on 1)

The imaging sensor of claim 1, wherein the near-infrared absorber is integrated among pixels of the optical black dummy pixel subarray.

### Claim 5 (depends on 1)

The imaging sensor of claim 1, wherein pixels of the optical black dummy pixel subarray adjacent to the near-infrared absorber are operated in a drain mode.

### Claim 6 (depends on 1)

The imaging sensor of claim 1, wherein the near-infrared absorber is not connected to a power supply voltage.

### Claim 7 (depends on 1)

The imaging sensor of claim 1, wherein the pixel array further includes an active dummy pixel region including a subarray of active dummy pixels positioned between the subarray of active multi-tap pixels and the subarray of optical black dummy pixels.

### Claim 8

An imaging sensor, comprising:
a pixel array comprising:
an active pixel region including an active multi-tap pixel subarray,
an optical black pixel region including an optical black multi-tap pixel subarray, and
an optical black dummy pixel region including an optical black dummy pixel subarray, the optical black dummy pixel region positioned between the active pixel region and the optical black pixel region;
a deep trench isolator extending between the optical black pixel region and the active pixel region; and
a controller configured to
supply a clocking signal to integrate light at a first tap of an optical black multi-tap pixel of the subarray of optical black multi-tap pixels to generate a first signal, and to integrate light at a second tap of the optical black multi-tap pixel to generate a second signal; and
apply a dark current correction to an active multi-tap pixel of the subarray of active multi-tap pixels based at least in part on the second signal.

### Claim 9 (depends on 8)

The imaging sensor of claim 8, wherein the deep trench isolator is at least partially filled with an oxide.

### Claim 10 (depends on 8)

The imaging sensor of claim 8, wherein the deep trench isolator is at least partially filled with a metal.

### Claim 11 (depends on 8)

The imaging sensor of claim 8, wherein the deep trench isolator is positioned within the optical black dummy pixel region.

### Claim 12 (depends on 8)

The imaging sensor of claim 8, further comprising:
a bulk silicon substrate; and
a near-infrared absorber positioned between the active pixel region and deep trench isolator, the near-infrared absorber fabricated from a material having a higher near-infrared absorption coefficient than that of silicon.

### Claim 13 (depends on 8)

The imaging sensor of claim 8, wherein the near-infrared absorber comprises germanium.

### Claim 14 (depends on 8)

The imaging sensor of claim 8, wherein the near-infrared absorber is positioned between the optical black dummy pixel subarray and an opaque light shield.

### Claim 15 (depends on 8)

The imaging sensor of claim 8, wherein the near-infrared absorber is integrated among pixels of the optical black dummy pixel subarray.

### Claim 16

A method for operating a multi-tap pixel, comprising:
supplying a clocking signal to integrate light at a first photogate of a pixel for a first duration of an integration period to generate a first signal, and to integrate light at a second photogate of the pixel for a second duration of the integration period to generate a second signal, the second duration shorter than the first duration; and
applying a dark current correction to the first signal, the dark current correction based at least in part on the second signal, wherein the dark current correction is further based at least in part on a predetermined dark current ratio between the first photogate and the second photogate.

### Claim 17 (depends on 16)

The method of claim 16, wherein a light signal at the second photogate is attenuated relative to a light signal at the first photogate.

### Claim 18 (depends on 16)

The method of claim 16, wherein the second duration is less than one percent of the integration period.

### Claim 19 (depends on 16)

The method of claim 16, wherein the pixel is an indirect time-of-flight pixel.