CN-122028530-A - Image sensor pixel circuit, manufacturing method thereof, image sensor and electronic equipment

Abstract

The invention provides an image sensor pixel circuit and a manufacturing method thereof, an image sensor and electronic equipment, belonging to the technical field of image sensors, and comprising a photodiode; and a carbon nanotube transistor electrically connected to the photodiode and the silicon-based transistor unit, respectively, for controlling charge transfer from the photodiode to the silicon-based transistor unit. The invention realizes charge transfer between the photodiode and the silicon-based transistor unit through the carbon nanotube transistor, can realize faster and more efficient charge transfer by utilizing the characteristics of high carrier mobility and good conductivity of the carbon nanotube material, improves the response speed of the pixel circuit of the image sensor, and simultaneously, the structure of the carbon nanotube can inhibit dark current, reduces the dark current of the pixel circuit of the image sensor and is beneficial to improving the quality of the image acquired by the image sensor.

Inventors

• NI PING
• YUAN YUANDONG
• CHEN YONGQIANG
• YU YANG
• GONG XUEMIN

Assignees

• 北京大学重庆碳基集成电路研究院

Dates

Publication Date

20260512

Application Date

20251230

Claims (10)

1. 1. An image sensor pixel circuit, comprising: A photodiode; a silicon-based transistor unit for converting charges generated by the photodiode into pixel signals; And the carbon nanotube transistor is respectively and electrically connected with the photodiode and the silicon-based transistor unit and is used for controlling charge transfer from the photodiode to the silicon-based transistor unit.
2. 2. The image sensor pixel circuit of claim 1, wherein the carbon nanotube transistor comprises: a carbon nanotube having a source region and a drain region provided at an interval on the same side; A gate dielectric on the same side of the carbon nanotube except for the source region and the drain region; A source metal on the source region of the carbon nanotube; A drain metal on the drain region of the carbon nanotube; A gate metal on the gate dielectric between the source region and the drain region; the source metal is electrically connected with the photodiode, and the drain metal is electrically connected with the silicon-based transistor unit.
3. 3. The image sensor pixel circuit of claim 1, wherein the photodiode is disposed at intervals in a horizontal direction with the silicon-based transistor unit, and the carbon nanotube transistor is disposed opposite to the silicon-based transistor unit in a vertical direction.
4. 4. The image sensor pixel circuit of claim 1, wherein the silicon-based transistor cell comprises a floating diffusion region, a first transistor, a second transistor, and a third transistor: The photodiode is connected with the floating diffusion region through the carbon nanotube transistor; the power supply is connected with the drain electrode of the first transistor, and the source electrode of the first transistor is connected with the floating diffusion region; The floating diffusion region is also connected with the grid electrode of the second transistor, the power supply is also connected with the drain electrode of the second transistor, the source electrode of the second transistor is connected with the drain electrode of the third transistor, and the source electrode of the third transistor is connected with the column bus.
5. 5. A method of manufacturing an image sensor pixel circuit, comprising: forming a photodiode, a silicon-based transistor unit and a carbon nanotube transistor respectively; And the photodiode is electrically connected with the carbon nanotube transistor, the carbon nanotube transistor and the silicon-based transistor unit.
6. 6. The method of manufacturing an image sensor pixel circuit according to claim 5, wherein forming the carbon nanotube transistor comprises: Depositing carbon nanotubes; Depositing a gate dielectric on the carbon nanotubes; removing the gate dielectric on the carbon nanotube source electrode region, and filling source electrode metal on the source electrode region; removing the gate dielectric on the carbon nanotube drain region, and filling drain metal on the drain region; and filling gate metal on the gate dielectric between the source electrode region and the drain electrode region.
7. 7. The method of manufacturing an image sensor pixel circuit according to claim 6, wherein the electrically connecting the photodiode with the carbon nanotube transistor, the carbon nanotube transistor with the silicon-based transistor unit comprises: etching a first through hole penetrating from the source metal to the photodiode and a second through hole penetrating from the drain metal to the silicon-based transistor unit respectively; And filling the first through hole and the second through hole with metal.
8. 8. The method of manufacturing an image sensor pixel circuit according to claim 5, wherein forming the photodiode, the silicon-based transistor unit, and the carbon nanotube transistor, respectively, comprises: and forming the photodiode and the silicon-based transistor unit at intervals in the horizontal direction, and forming the carbon nanotube transistor at a position opposite to the silicon-based transistor unit in the vertical direction.
9. 9. An image sensor comprising an array of a plurality of image sensor pixel circuits according to any one of claims 1 to 4.
10. 10. An electronic device comprising the image sensor of claim 9.

Description

Image sensor pixel circuit, manufacturing method thereof, image sensor and electronic equipment Technical Field The present invention relates to the field of image sensors, and more particularly, to an image sensor pixel circuit, a method for manufacturing the same, an image sensor, and an electronic device. Background The image sensor pixel circuit is used for converting the optical signal into the pixel signal, and the problems of slow response speed and large dark current of the traditional image sensor pixel circuit lead to slow response speed and poor acquired image quality of the traditional image sensor. Disclosure of Invention The invention provides an image sensor pixel circuit, a manufacturing method thereof, an image sensor and electronic equipment, which are used for solving the technical problems of low response speed and large dark current of the image sensor pixel circuit in the prior art. The invention provides an image sensor pixel circuit, comprising: A photodiode; a silicon-based transistor unit for converting charges generated by the photodiode into pixel signals; And the carbon nanotube transistor is respectively and electrically connected with the photodiode and the silicon-based transistor unit and is used for controlling charge transfer from the photodiode to the silicon-based transistor unit. According to the present invention, there is provided an image sensor pixel circuit, the carbon nanotube transistor comprising: a carbon nanotube having a source region and a drain region provided at an interval on the same side; A gate dielectric on the same side of the carbon nanotube except for the source region and the drain region; A source metal on the source region of the carbon nanotube; A drain metal on the drain region of the carbon nanotube; A gate metal on the gate dielectric between the source region and the drain region; the source metal is electrically connected with the photodiode, and the drain metal is electrically connected with the silicon-based transistor unit. According to the image sensor pixel circuit provided by the invention, the photodiode and the silicon-based transistor unit are arranged at intervals along the horizontal direction, and the carbon nanotube transistor and the silicon-based transistor unit are arranged opposite to each other along the vertical direction. According to the image sensor pixel circuit provided by the invention, the silicon-based transistor unit comprises a floating diffusion region, a first transistor, a second transistor and a third transistor: The photodiode is connected with the floating diffusion region through the carbon nanotube transistor; the power supply is connected with the drain electrode of the first transistor, and the source electrode of the first transistor is connected with the floating diffusion region; The floating diffusion region is also connected with the grid electrode of the second transistor, the power supply is also connected with the drain electrode of the second transistor, the source electrode of the second transistor is connected with the drain electrode of the third transistor, and the source electrode of the third transistor is connected with the column bus. The invention also provides a manufacturing method of the pixel circuit of the image sensor, which comprises the following steps: forming a photodiode, a silicon-based transistor unit and a carbon nanotube transistor respectively; And the photodiode is electrically connected with the carbon nanotube transistor, the carbon nanotube transistor and the silicon-based transistor unit. According to the method for manufacturing the pixel circuit of the image sensor provided by the invention, the carbon nanotube transistor is formed, and the method comprises the following steps: Depositing carbon nanotubes; Depositing a gate dielectric on the carbon nanotubes; removing the gate dielectric on the carbon nanotube source electrode region, and filling source electrode metal on the source electrode region; removing the gate dielectric on the carbon nanotube drain region, and filling drain metal on the drain region; and filling gate metal on the gate dielectric between the source electrode region and the drain electrode region. According to the method for manufacturing the pixel circuit of the image sensor, the electrical connection between the photodiode and the carbon nanotube transistor, between the carbon nanotube transistor and the silicon-based transistor unit, comprises the following steps: etching a first through hole penetrating from the source metal to the photodiode and a second through hole penetrating from the drain metal to the silicon-based transistor unit respectively; And filling the first through hole and the second through hole with metal. According to the present invention, there is provided a method for manufacturing a pixel circuit of an image sensor, the method for forming a photodiode, a silicon-based transistor unit and a carbon nanotube trans