# US 12,119,285 B2 · Image sensor with actively cooled sensor array

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- Number: US 12,119,285 B2
- Document ID: US12119285B2
- Status: Granted
- Kind: B2
- Application number: 17/446,954
- Filed: 2021-09-03
- Published: 2023-03-09
- Granted: 2024-10-15
- Earliest claimed: 2021-09-03
- 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/US12119285B2

## CPC

- H10F 39/80: {Constructional details of image sensors}
- H10F 39/807: {Pixel isolation structures}
- H10F 39/026: {Wafer-level processing}
- H10F 77/60: Arrangements for cooling, heating, ventilating or compensating for temperature fluctuations
- H10W 40/28: comprising Peltier coolers
- H10F 39/199: {Back-illuminated image sensors}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

An image sensor comprises an array of sensor elements, each responsive to incident photon flux, and a readout circuit coupled electronically to the array of sensor elements and configured to release an electronic signal varying in dependence on the incident photon flux. A thermal-barrier zone separates the array of sensor elements from the readout circuit, and a solid-state cooler is coupled thermally to the array of sensor elements.

## Claims

### Claim 1

An image sensor comprising:
an array of sensor elements each responsive to incident photon flux;
a readout circuit coupled electronically to the array of sensor elements and configured to release an electronic signal varying in dependence on the incident photon flux;
a thermal-barrier zone separating the array of sensor elements from the readout circuit; and
a solid-state cooler coupled thermally to the array of sensor elements, the solid-state cooler including:
an alternating series of p+-doped and n+-doped silicon bridges that lay across the thermal-barrier zone, between the array of sensor elements and the readout circuit, and
a plurality of bridge links, each joining a pair of adjacent, non-terminal bridges of the alternating series, on opposite ends of the thermal-barrier zone.

### Claim 2 (depends on 1)

The image sensor of claim 1 wherein the array of sensor elements and the readout circuit are formed on a sensor-wafer substrate and wherein the thermal-barrier zone includes a sensor-wafer trench etched into the sensor-wafer substrate.

### Claim 3 (depends on 2)

The image sensor of claim 2 wherein the sensor-wafer substrate supports an epitaxial structure comprising the array of sensor elements and the readout circuit, wherein the epitaxial structure is bonded to a carrier-wafer substrate, and wherein the thermal-barrier zone includes a carrier-wafer trench etched into the carrier-wafer substrate.

### Claim 4 (depends on 3)

The image sensor of claim 3 wherein the substrate-wafer trench and carrier-wafer trench are co-registered.

### Claim 5 (depends on 3)

The image sensor of claim 3 wherein one or both of the substrate-wafer trench and the carrier-wafer trench include a solid fill material of lower thermal conductivity than the substrate-wafer substrate or the carrier-wafer substrate.

### Claim 6 (depends on 5)

The image sensor of claim 5 wherein the fill material is silicon oxide formed via CMOS processing.

### Claim 7 (depends on 1)

The image sensor of claim 1 wherein the solid-state cooler comprises a Peltier-effect cooler.

### Claim 8 (depends on 1)

The image sensor of claim 1 wherein the solid-state cooler is arranged within the thermal-barrier zone.

### Claim 9 (depends on 8)

The image sensor of claim 8 wherein the array of sensor elements is a CMOS array, and wherein the solid-state cooler is fabricated within the thermal-barrier zone via CMOS processing.

### Claim 10 (depends on 1)

The image sensor of claim 1 wherein each p+-doped and n+-doped silicon bridge comprises a silicon nanowire narrow enough to exhibit quantum confinement of phonons traversing the bridge.

### Claim 11 (depends on 1)

The image sensor of claim 1 wherein each bridge link includes an electronically conductive ceramic.

### Claim 12 (depends on 1)

The image sensor of claim 1 wherein each bridge link includes a metal.

### Claim 13

An image sensor comprising:
a carrier-wafer substrate;
a sensor-wafer substrate supporting an epitaxial structure bonded to the carrier-wafer substrate;
formed in the epitaxial structure, an array of sensor elements each responsive to incident photon flux;
formed in the epitaxial structure, a readout circuit coupled electronically to the array of sensor elements and configured to release an electronic signal varying in dependence on the incident photon flux;
a thermal-barrier zone separating the array of sensor elements from the readout circuit, the thermal-barrier zone including a sensor-wafer trench etched into the sensor-wafer substrate and a co-registered carrier-wafer trench etched into the carrier-wafer substrate; and
a Peltier-effect cooler including:
an alternating series of p+-doped and n+-doped silicon bridges that lay across the thermal-barrier zone, between the array of sensor elements and the readout circuit; and
a plurality of bridge links, each joining a pair of adjacent, non-terminal bridges of the alternating series, on opposite ends of the thermal-barrier zone.

### Claim 14 (depends on 13)

The image sensor of claim 13 wherein each bridge link comprises titanium nitride or cobalt.