# US 9,520,439 B2 · X-ray and optical image sensor

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- Number: US 9,520,439 B2
- Document ID: US9520439B2
- Status: Granted
- Kind: B2
- Application number: 14/034,210
- Filed: 2013-09-23
- Published: 2015-03-26
- Granted: 2016-12-13
- Earliest claimed: 2013-09-23
- Assignees: OmniVision Technologies, Inc.
- Applicants: Omnivision Technologies, Inc.
- Inventors: Dominic Massetti; Yu Zheng
- Web page: https://patentgrep.com/patent/US9520439B2

## CPC

- H10F 39/195: {X-ray, gamma-ray or corpuscular radiation imagers}
- G01N 23/083: the radiation being X-rays
- G01T 1/2019: {Shielding against direct hits}
- H10F 39/024: {of coatings or optical elements}
- H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
- H10F 39/199: {Back-illuminated image sensors}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00)

## Abstract

An image sensor for capturing X-ray image data and optical image data includes an X-ray absorption layer and a plurality of photodiodes disposed in a semiconductor layer. The X-ray absorption layer is configured to emit photons in response to receiving X-ray radiation. The plurality of photodiodes disposed in the semiconductor layer is optically coupled to receive image light to generate the optical image data, and is optically coupled to receive photons from the X-ray absorption layer to generate X-ray image data.

## Claims

### Claim 1

An image sensor for capturing X-ray image data of an object and optical image data of the object, the image sensor comprising:
an X-ray absorption layer configured to emit photons in response to receiving X-ray radiation of the object;
a plurality of photodiodes disposed in a semiconductor layer having a first side opposite a second side, wherein the plurality of photodiodes are optically coupled to receive image light of the object to generate the optical image data, and wherein the plurality of photodiodes are optically coupled to receive the photons from the X-ray absorption layer to generate the X-ray image data, the plurality of photodiodes positioned to receive the photons from the X-ray absorption layer through only the second side of the semiconductor layer and positioned to receive the image light through the first side of the semiconductor layer, wherein the image sensor is configured to receive the image light propagating from outside the image sensor, and wherein the X-ray absorption layer is disposed proximate to the second side of the semiconductor layer; and
one or more microlenses disposed proximate to the first side of the semiconductor layer, wherein the X-ray radiation and the image light propagate through the one or more microlenses, and wherein the microlenses focus the image light into the plurality of photodiodes.

### Claim 2 (depends on 1)

The image sensor of claim 1, further comprising a reflective layer positioned to direct the photons towards the plurality of photodiodes, wherein the X-ray absorption layer is disposed between the reflective layer and the second side of the semiconductor layer.

### Claim 3 (depends on 2)

The image sensor of claim 2, wherein the reflective layer comprises aluminum.

### Claim 4 (depends on 1)

The image sensor of claim 1, further comprising:
one or more intermediate layers disposed between the second side of the semiconductor layer and the X-ray absorption layer; and
electronic interconnects embedded in the one or more intermediate layers.

### Claim 5 (depends on 1)

The image sensor of claim 1 further comprising:
one or more intermediate layers disposed between the one or more microlenses and the first side of the semiconductor layer.

### Claim 6 (depends on 1)

The image sensor of claim 1, wherein the X-ray absorption layer includes a phosphor.

### Claim 7 (depends on 1)

The image sensor of claim 1, further comprising:
transistors coupled to readout the plurality of photodiodes; and
X-ray shield layers positioned to block the X-ray radiation from reaching the transistors.

### Claim 8 (depends on 7)

The image sensor of claim 7, wherein the X-ray shield layers comprise metal.

### Claim 9 (depends on 1)

The image sensor of claim 1, wherein the X-ray absorption layer is positioned to receive the X-ray radiation through the plurality of photodiodes.

### Claim 10 (depends on 1)

The image sensor of claim 1, further comprising:
readout circuitry coupled to the plurality of photodiodes to readout the optical image data and the X-ray image data from the plurality of photodiodes.

### Claim 11 (depends on 1)

The image sensor of claim 1, wherein the plurality of photodiodes is arranged into a pixel array comprising rows and columns.

### Claim 12

An imaging system comprising:
an X-ray emitter for emitting an X-ray beam toward an object;
a controller coupled to the X-ray emitter to control the emission of the X-ray beam; and
an image sensor for capturing X-ray image data of the object and optical image data of the object, wherein the controller is coupled to the image sensor to control image capture, the image sensor comprising:
an X-ray absorption layer configured to emit photons in response to receiving the X-ray beam;
a plurality of photodiodes disposed in a semiconductor layer having a first side opposite a second side, wherein the plurality of photodiodes are optically coupled to receive image light of the object to generate the optical image data, and wherein the plurality of photodiodes are optically coupled to receive the photons from the X-ray absorption layer to generate the X-ray image data, the plurality of photodiodes positioned to receive the photons from the X-ray absorption layer through only the second side of the semiconductor layer and positioned to receive the image light through the first side of the semiconductor layer, wherein the image sensor is configured to receive the image light from outside the image sensor, and wherein the X-ray absorption layer is disposed proximate to the second side of the semiconductor layer; and
one or more microlenses disposed proximate to the first side of the semiconductor layer, wherein the X-ray beam and the image light propagate through the one or more microlenses, and wherein the microlenses focus the image light into the plurality of photodiodes.

### Claim 13 (depends on 12)

The imaging system of claim 12 further comprising a light source coupled to provide source light to a subject to be imaged, wherein the controller is coupled to the light source to control emissions of the source light.

### Claim 14 (depends on 13)

The imaging system of claim 13, wherein the source light emitted by the light source is non-visible light, and wherein the image sensor includes a filter that filters out visible light from reaching the plurality of photodiodes.

### Claim 15

A method of fabricating an image sensor for capturing X-ray image data of an object and optical image data of the object, the method comprising:
forming an X-ray absorption layer configured to emit photons in response to receiving X-ray radiation of an object;
forming a plurality of photodiodes in a semiconductor layer having a first side opposite a second side, wherein the plurality of photodiodes are optically coupled to receive image light to generate the optical image data, and wherein the plurality of photodiodes are optically coupled to receive the photons from the X-ray absorption layer to generate the X-ray image data, the plurality of photodiodes positioned to receive the photons from the X-ray absorption layer through only the second side of the semiconductor layer and positioned to receive the image light through the first side of the semiconductor layer, wherein the image sensor is configured to receive the image light propagating from outside the image sensor, and wherein the X-ray absorption layer is disposed proximate to the second side of the semiconductor layer; and
forming one or more microlenses disposed proximate to the first side of the semiconductor layer, wherein the X-ray radiation and the image light propagate through the one or more microlenses, and wherein the microlenses focus the image light into the plurality of photodiodes.

### Claim 16 (depends on 15)

The method of claim 15, wherein forming the X-ray absorption layer comprises depositing the X-ray absorption layer on the semiconductor layer.

### Claim 17 (depends on 15)

The method of claim 15, wherein forming the X-ray absorption layer comprises bonding the X-ray absorption layer to the semiconductor layer.