US 2023/0067685 A1 · IMAGE SENSOR WITH VERTICAL TRANSFER GATE

Abstract

A pixel of an image sensor includes a semiconductor substrate having a front surface and a back surface opposing the front surface, a photodiode and floating diffusion (FD) region formed in the substrate along a first pixel axis parallel to the front surface and a transfer gate formed in the front surface of the substrate between the photodiode and the FD region. The transfer gate includes a planar gate on the front surface of the substrate, a vertical transfer gate extending into the substrate from the planar gate, the vertical transfer gate further including a trench and a layer of doped semiconductor material epitaxially grown on the sides and bottom of the trench. The semiconductor substrate and the epitaxial layer comprise a first conductive type, and the photodiode and the FD region comprise a second conductive type. An image sensor and method of forming the vertical transfer gate are disclosed.

Claims20

Dependent claims

A pixel of an image sensor comprising:

a semiconductor substrate having a front surface and a back surface opposing the front surface;
a photodiode in the semiconductor substrate;
a floating diffusion (FD) region formed in the semiconductor substrate and separated from the photodiode along a first pixel axis parallel to the front surface;
and
a transfer gate formed in the front surface of the semiconductor substrate to couple the photodiode to the FD region, the transfer gate comprising:
a planar gate on the front surface of the semiconductor substrate;
a first vertical transfer gate extending a depth into the semiconductor substrate from the planar gate and located between the photodiode and the FD region along the first pixel axis, the first vertical transfer gate further comprising:
a first trench;
and
a layer of doped semiconductor material epitaxially grown on the sides and bottom of the first trench;
wherein the semiconductor substrate and the epitaxially grown doped semiconductor material layer comprise a first conductive type, and the photodiode and the FD region comprise a second conductive type opposite to the first conductive type.

8 more elements

An image sensor comprising

a semiconductor substrate having a front surface and a back surface opposing the front surface;
a plurality of photodiodes formed in the semiconductor substrate;
a floating diffusion (FD) region formed in the semiconductor substrate adjacent to the plurality of photodiodes, the floating diffusion region separated from each photodiode along a respective first pixel axis parallel to the front surface;
a plurality of transfer gates corresponding to the plurality of photodiodes formed in the front surface of the semiconductor substrate to couple each respective photodiode to the FD region, each of the transfer gates formed along a respective second pixel axis parallel to the front surface and perpendicular to the first pixel axis of the corresponding photodiode, each transfer gate comprising:
a planar gate on the front surface of the semiconductor substrate;
a first vertical transfer gate extending a depth into the semiconductor substrate from the planar gate and located between the photodiode and the FD region along the first pixel axis, the first vertical transfer gate further comprising:
a first trench;
and
a layer of doped semiconductor material epitaxially grown on the sides and bottom of the first trench;
wherein the semiconductor substrate and the layer of doped semiconductor material comprise a first conductive type, and each of the photodiode and the FD region comprises a second conductive type opposite to the first conductive type.

7 more elements

Dependencies are inferred from the claim text.

Image sensor with vertical transfer gate

Life of this patent

Image sensor with vertical transfer gate

Life of this patent

Abstract

Claims20