US 2024/0186360 A1 · PIXEL UNIT, OPTICAL DETECTOR, FORMATION METHOD, THE READOUT METHOD

Abstract

A pixel unit includes: a base, the base including a substrate, a photosensitive element, and memory nodes; overflow doping regions in the second surface of the substrate; and overflow interconnection structures electrically connected to the overflow doping regions. Vertical-overflow-drain structures are formed between the overflow doping regions and the memory nodes, allowing the charge stored in the memory nodes to be discharged at a certain rate through the overflow interconnection structures. This configuration reduces the oversaturation of memory nodes effectively without altering the exposure time or affecting circuit power consumption, thereby addressing background noise issue. Furthermore, the memory nodes and the overflow doping regions are in the first and second surfaces of the substrate, respectively. Therefore, the placement of the overflow doping regions does not affect the area of the pixel unit, and the resolution of the photosensor is preserved.

Claims20

Dependent claims

A pixel unit for an optical detector, comprising:

a base, including a substrate having a first surface and a second surface opposite to the first surface;
a photosensitive element in the first surface of the substrate;
a plurality of memory nodes in the first surface of the substrate, wherein the plurality of memory nodes are spaced apart from the photosensitive element;
a plurality of overflow doping regions in the second surface of the substrate, wherein locations of the plurality of overflow doping regions correspond to locations of the plurality of memory nodes, and a doping type of the plurality of overflow doping regions is same as a doping type of the plurality of doping regions of the plurality of memory nodes;
and
a plurality of overflow interconnection structures over the plurality of overflow doping regions, wherein the plurality of overflow interconnection structures are electrically connected to the plurality of overflow doping regions.

3 more elements

A method for forming an optical detector, comprising:

providing a base including a substrate having a first surface and a second surface opposite to the first surface;
providing a photosensitive element in the first surface of the substrate;
providing a plurality of memory nodes in the first surface of the substrate, wherein the plurality of memory nodes are spaced apart from the photosensitive element;
forming a plurality of overflow doping regions in the second surface of the substrate, wherein the second surface is opposite to the first surface, locations of the plurality of overflow doping regions correspond to locations of the plurality of memory nodes, and a doping type of the plurality of overflow doping regions is same as a doping type of the plurality of doping regions of the memory nodes;
and
forming a plurality of overflow interconnection structures over the plurality of overflow doping regions, wherein the plurality of overflow interconnection structures are electrically connected to the plurality of overflow doping regions.

3 more elements

Dependencies are inferred from the claim text.

Pixel unit, optical detector, formation method, the readout method

Life of this patent

Pixel unit, optical detector, formation method, the readout method

Life of this patent

Abstract

Claims20