# US 2021/0242270 A1 · Image sensor including transistor including protruding channel electrode

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- Number: US 2021/0242270 A1
- Document ID: US20210242270A1
- Status: Published application
- Kind: A1
- Application number: 16/904,708
- Filed: 2020-06-18
- Published: 2021-08-05
- Earliest claimed: 2020-02-05
- Assignees: Samsung Electronics Co., Ltd.
- Applicants: Samsung Electronics Co., Ltd.
- Inventors: Kangmook LIM; Sungin KIM; Changhwa KIM; Yeoseon CHOI
- Web page: https://patentgrep.com/patent/US20210242270A1

## CPC

- H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
- H10F 39/802: {Geometry or disposition of elements in pixels, e.g. address-lines or gate electrodes}
- H10F 39/80373: {characterised by the gate of the transistor}
- H10F 39/80377: {characterised by the channel of the transistor, e.g. channel having a doping gradient}
- H10F 39/8053: {Colour filters}
- H10F 39/807: {Pixel isolation structures}
- H10F 39/199: {Back-illuminated image sensors}
- H10F 39/8063: {Microlenses}
- H10F 39/809: {of hybrid image sensors}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

An image sensor is disclosed. The image sensor includes first, second, third and fourth unit pixels. Each of the unit pixels includes a first transfer transistor structure, a second transfer transistor structure and a third transfer transistor structure, a first source follower transistor structure, a second source follower transistor structure and a third source follower transistor structure, and a first selection transistor structure, a second selection transistor structure and a third selection transistor structure, the fourth unit pixel includes a fourth transfer transistor structure and a reset transistor structure, and each of the transfer transistor structures includes a channel electrode and a gate structure that surrounds side surfaces of the channel electrode.

## Claims

### Claim 1

An image sensor comprising:
a plurality of unit pixels arranged in a matrix form, the plurality of unit pixels comprising a first unit pixel, a second unit pixel, a third unit pixel and a fourth unit pixel,
wherein each of the first unit pixel, the second unit pixel and the third unit pixel comprises a first transfer transistor structure, a second transfer transistor structure and a third transfer transistor structure, a first source follower transistor structure, a second source follower transistor structure and a third source follower transistor structure, and a first selection transistor structure, a second selection transistor structure and a third selection transistor structure,
wherein the fourth unit pixel comprises a fourth transfer transistor structure and a reset transistor structure, and
wherein each of the first transfer transistor structure, the second transfer transistor structure, the third transfer transistor structure and the fourth transfer transistor structure comprises a channel electrode and a gate structure that surrounds side surfaces of the channel electrode.

### Claim 2 (depends on 1)

The image sensor of claim 1, wherein the reset transistor structure comprises a reset transistor channel electrode and a reset transistor gate structure that surrounds side surfaces of the reset transistor channel electrode.

### Claim 3 (depends on 2)

The image sensor of claim 2, wherein the fourth unit pixel further comprises a source voltage electrode, and
wherein the source voltage electrode protrudes from a surface of a substrate.

### Claim 4 (depends on 3)

The image sensor of claim 3, wherein the fourth unit pixel further comprises a well area and a source area each formed in the substrate, and
wherein in a top view, the source area vertically overlaps the source voltage electrode and the channel electrode of the reset transistor structure, and the well area surrounds the source area.

### Claim 5 (depends on 2)

The image sensor of claim 2, wherein the reset transistor gate structure comprises a reset transistor gate insulation layer and a reset transistor gate electrode, and
wherein in a vertical cross-sectional view, the reset transistor gate insulation layer has an L-shape that surrounds one side surface and a bottom surface of the reset transistor gate electrode.

### Claim 6 (depends on 1)

The image sensor of claim 1, wherein in a top view, each of the first source follower transistor structure, the second source follower transistor structure and the third source follower transistor structure comprises a source follower transistor channel electrode and a source follower transistor gate structure that surrounds side surfaces of the source follower transistor channel electrode, and
each of the first selection transistor structure, the second selection transistor structure and the third selection transistor structure comprises a selection transistor channel electrode and a selection transistor gate structure that surrounds side surfaces of the selection transistor channel electrode.

### Claim 7 (depends on 6)

The image sensor of claim 6, wherein each of the first unit pixel, the second unit pixel and the third unit pixel further comprises a well area and a source area each formed in a substrate, and
wherein in the top view, the source area overlaps the source follower transistor channel electrode of a source follower transistor structure and the selection transistor channel electrode of a selection transistor structure, and the well area surrounds the source area.

### Claim 8 (depends on 6)

The image sensor of claim 6, wherein each of the first unit pixel, the second unit pixel and the third unit pixel further comprises a well area and a source area each formed in a substrate, and
wherein in the top view, the source area overlaps the source follower transistor channel electrode of a source follower transistor structure and the selection transistor channel electrode of a selection transistor structure, and the well area surrounds the source area.

### Claim 9 (depends on 1)

The image sensor of claim 1, wherein the first unit pixel further comprises a first photodiode, the second unit pixel further comprises a second photodiode, the third unit pixel further comprises a third photodiode and the fourth unit pixel further comprises a fourth photodiode, wherein each of the first photodiode, the second photodiode, the third photodiode and the fourth photodiode is formed in a substrate,
wherein in a top view, the first transfer transistor structure, the first source follower transistor structure, and the first selection transistor structure of the first unit pixel are vertically aligned with and overlap the first photodiode,
wherein in the top view, the second transfer transistor structure, the second source follower transistor structure, and the second selection transistor structure of the second unit pixel are vertically aligned with and overlap the second photodiode,
wherein in the top view, the third transfer transistor structure, the third source follower transistor structure, and the third selection transistor structure of the third unit pixel are vertically aligned with and overlap the third photodiode, and
wherein in the top view, the fourth transfer transistor structure and the reset transistor structure of the fourth unit pixel are vertically aligned with and overlap the fourth photodiode.

### Claim 10 (depends on 9)

The image sensor of claim 9, further comprising:
a plurality of isolation areas interposed between the first photodiode, the second photodiode, the third photodiode, and the fourth photodiode; and
a first color filter, a second color filter, a third color filter, a fourth color filter, a first lens, a second lens, a third lens, a fourth lens disposed on the substrate to respectively and vertically overlap the first photodiode, the second photodiode, the third photodiode, and the fourth photodiode, respectively.

### Claim 11 (depends on 1)

The image sensor of claim 1, wherein in a vertical cross-sectional view, the channel electrode of each of the first transfer transistor structure, the second transfer transistor structure, the third transfer transistor structure and the fourth transfer transistor structure has a pillar shape that protrudes from a substrate, and
wherein a lower portion of the pillar shape comprises a source area, a middle portion of the pillar shape comprises a channel area, and an upper portion of the pillar shape comprises a drain area.

### Claim 12 (depends on 11)

The image sensor of claim 11, wherein the drain area comprises metal silicide.

### Claim 13 (depends on 11)

The image sensor of claim 11, wherein the upper portion of each of the first transfer transistor structure, the second transfer transistor structure, the third transfer transistor structure and the fourth transfer transistor structure are integrated as one body.

### Claim 14

An image sensor comprising:
a photodiode formed in a substrate; and
a transfer transistor structure, a source follower transistor structure, and a selection transistor structure each formed on the substrate,
wherein the transfer transistor structure comprises a transfer transistor channel electrode and a transfer transistor gate structure that surrounds side surfaces of the transfer transistor channel electrode,
wherein the source follower transistor structure comprises a source follower transistor channel electrode and a source follower transistor gate structure that surrounds side surfaces of the source follower transistor channel electrode,
wherein the selection transistor structure comprises a selection transistor channel electrode and a selection transistor gate structure that surrounds side surfaces of the selection transistor channel electrode,
wherein the transfer transistor channel electrode, the source follower transistor channel electrode, and the selection transistor channel electrode protrude from a surface of the substrate, and
wherein the transfer transistor structure, the source follower transistor structure, and the selection transistor structure are vertically aligned with and overlap the photodiode.

### Claim 15 (depends on 14)

The image sensor of claim 14, wherein the photodiode comprises a first photodiode, a second photodiode, a third photodiode and a fourth photodiode, and
wherein the transfer transistor structure comprises a first transfer transistor structure, a second transfer transistor structure, a third transfer transistor structure and a fourth transfer transistor structure,
wherein the source follower transistor structure comprises a first source follower transistor structure, a second source follower transistor structure and a third source follower transistor structure,
wherein the selection transistor structure comprises a first selection transistor structure, a second selection transistor structure and a third selection transistor structure,
wherein the first photodiode, the first transfer transistor structure, the first source follower transistor structure, and the first selection transistor structure are vertically aligned and overlap,
wherein the second photodiode, the second transfer transistor structure, the second source follower transistor structure, and the second selection transistor structure are vertically aligned and overlap, and
wherein the third photodiode, the third transfer transistor structure, the third source follower transistor structure, and the third selection transistor structure are vertically aligned and overlap.

### Claim 16 (depends on 15)

The image sensor of claim 15, further comprising:
a first ground voltage electrode vertically aligned with the first photodiode to overlap the first photodiode;
a second ground voltage electrode vertically aligned with the second photodiode to overlap the second photodiode;
a third ground voltage electrode vertically aligned with the third photodiode to overlap the third photodiode.

### Claim 17 (depends on 15)

The image sensor of claim 15, further comprising a reset transistor structure,
wherein the reset transistor structure is vertically aligned with and overlaps the fourth photodiode.

### Claim 18 (depends on 17)

The image sensor of claim 17, further comprising a source voltage electrode vertically aligned with the fourth photodiode to overlap the fourth photodiode.

### Claim 19

An image sensor comprising:
a lower device and an upper device stacked on the lower device,
wherein the lower device comprises a logic circuit disposed on a lower substrate,
wherein the upper device comprises a plurality of photodiodes formed in an upper substrate, a plurality of cell circuits disposed on a bottom surface of the upper substrate, and a plurality of color filters disposed on a top surface of the upper substrate,
wherein each of the plurality of cell circuits comprises a transfer transistor structure, a source follower transistor structure, and a selection transistor structure,
wherein the transfer transistor structure of each of the plurality of cell circuits is vertically aligned with one of the plurality of photodiodes, and comprises a transfer transistor channel electrode protruding from the bottom surface of the upper substrate and a transfer transistor gate structure surrounding side surfaces of the transfer transistor channel electrode,
wherein the source follower transistor structure of each of the plurality of cell circuits is vertically aligned with one of the plurality of photodiodes, and comprises a source follower transistor channel electrode protruding from the bottom surface of the upper substrate and a source follower transistor gate structure surrounding side surfaces of the source follower transistor channel electrode, and
wherein the selection transistor structure of each of the plurality of cell circuits is vertically aligned with one of the plurality of photodiodes, and comprises a selection transistor channel electrode protruding from the bottom surface of the upper substrate and a selection transistor gate structure surrounding side surfaces of the selection transistor channel electrode.

### Claim 20 (depends on 19)

The image sensor of claim 19, further comprising a through-silicon via that is electrically connected to the logic circuit of the lower device and penetrates through the upper device.