# US 2021/0242274 A1 · Image sensor structure and method of forming the same

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- Number: US 2021/0242274 A1
- Document ID: US20210242274A1
- Status: Published application
- Kind: A1
- Application number: 16/779,655
- Filed: 2020-02-02
- Published: 2021-08-05
- Earliest claimed: 2020-02-02
- Assignees: Himax Imaging Limited
- Applicants: Himax Imaging Limited
- Inventors: Amit MITTRA; Yang WU; Ki-Hong KIM
- Web page: https://patentgrep.com/patent/US20210242274A1

## CPC

- H10F 39/024: {of coatings or optical elements}
- H10F 39/182: {Colour image sensors}
- H10F 39/184: {Infrared image sensors}
- 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 39/8053: {Colour filters}
- H10F 39/8063: {Microlenses}
- 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

## Abstract

An image sensor structure has a visible light detection region and an infrared light detection region neighboring the visible light detection region. The image sensor structure includes a semiconductor substrate, photo sensing members, an infrared absorption enhancing member, a color filter and an infrared pass filter. The semiconductor substrate has a front side and a back side opposite to each other. The first photo sensing member is disposed in the front side of the semiconductor substrate. The infrared absorption enhancing member is in the back side of the semiconductor substrate and only in the infrared light detection region. The color filter is over the back side of the semiconductor substrate and in the visible light detection region. The infrared pass filter is over the infrared absorption enhancing member.

## Claims

### Claim 1

An image sensor structure having a visible light detection region and an infrared light detection region neighboring the visible light detection region, the image sensor structure comprising:
a semiconductor substrate having a front side and a back side opposite to each other;
a plurality of photo sensing members disposed in the front side of the semiconductor substrate;
at least one infrared absorption enhancing member in the back side of the semiconductor substrate and only in the infrared light detection region;
a color filter over the back side of the semiconductor substrate and in the visible light detection region; and
an infrared pass filter over the at least one infrared absorption enhancing member.

### Claim 2 (depends on 1)

The image sensor structure of claim 1, further comprising:
an infrared notch filter over the back side of the semiconductor substrate and in the visible light detection region.

### Claim 3 (depends on 2)

The image sensor structure of claim 2, wherein the infrared notch fitter is interposed between the semiconductor substrate and the color filter.

### Claim 4 (depends on 1)

The image sensor structure of claim 1, further comprising:
a plurality of microlenses respectively over the color filter and the infrared pass filter.

### Claim 5 (depends on 1)

The image sensor structure of claim 1, wherein the infrared pass filter has a wavelength pass band in a range from 700 nm to 1100 nm.

### Claim 6 (depends on 5)

The image sensor structure of claim 5, wherein the wavelength pass band of the infrared pass filter has a center pass wavelength of about 850 nm.

### Claim 7 (depends on 5)

The image sensor structure of claim 5, wherein the wavelength pass band of the infrared pass filter has a center pass wavelength of about 940 nm.

### Claim 8 (depends on 1)

The image sensor structure of claim 1, further comprising:
a device layer over the front side of the semiconductor substrate; and
a carrier substrate over the device layer.

### Claim 9 (depends on 1)

The image sensor structure of claim 1, wherein the at least one infrared absorption enhancing member comprises silicon dioxide.

### Claim 10

A method of forming an image sensor structure with a visible light detection region and an infrared light detection region neighboring the visible light detection region, the method comprising:
providing a semiconductor substrate with a front side and a back side opposite to each other,
forming a plurality of photo sensing members in the front side of the semiconductor substrate;
forming at least one infrared absorption enhancing member in the back side of the semiconductor substrate and only in the infrared light detection region;
forming a color filter over the back side of the semiconductor substrate; and
forming an infrared pass filter over the at least one infrared absorption enhancing member.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
forming an infrared notch filter over the back side of the semiconductor substrate and in the visible light detection region.

### Claim 12 (depends on 11)

The method of claim 11, wherein the color filter is formed over the infrared notch fitter.

### Claim 13 (depends on 10)

The method of claim 10, further comprising:
forming a plurality of microlenses respectively over the color filter and the infrared pass filter.

### Claim 14 (depends on 10)

The method of claim 10, wherein the infrared pass filter is formed having a wavelength pass band in a range from 700 nm to 1100 nm.

### Claim 15 (depends on 14)

The method of claim 14, wherein the wavelength pass band of the infrared pass filter has a center pass wavelength of about 850 nm.

### Claim 16 (depends on 14)

The method of claim 14, wherein the wavelength pass band of the infrared pass filter has a center pass wavelength of about 940 nm.

### Claim 17 (depends on 10)

The method of claim 10, further comprising:
forming a device layer over the front side of the semiconductor substrate; and
forming a carrier substrate over the device layer.

### Claim 18 (depends on 10)

The method of claim 10, wherein the at least one infrared absorption enhancing member is formed of silicon dioxide.