Pixel device layout to reduce pixel noise
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorSeiji Takahashi
Life of this patent
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Abstract
Various embodiments of the present disclosure are directed towards a method for forming an image sensor, the method includes forming a first photodetector and a second photodetector in a substrate. An isolation structure is formed in the substrate between the first photodetector and the second photodetector. A readout transistor is formed over the isolation structure. The readout transistor includes a first sidewall directly over the first photodetector and a second sidewall directly over the second photodetector. A height of the readout transistor from the first sidewall to the second sidewall is constant.
Claims20
A method for forming an image sensor, comprising:
- forming a first photodetector and a second photodetector in a substrate;
- forming an isolation structure in the substrate between the first photodetector and the second photodetector;
- and
- forming a readout transistor over the isolation structure, wherein the readout transistor comprises a first sidewall over the first photodetector and a second sidewall over the second photodetector, wherein a height of the readout transistor from the first sidewall to the second sidewall is constant;
- and
- doping the substrate to form a floating diffusion node within the substrate and adjacent to the first photodetector, wherein a gate of the readout transistor is directly electrically coupled to the floating diffusion node.
A method for forming an image sensor, comprising:
- performing a doping process to form a first photodetector, a second photodetector, and a third photodetector within a substrate, wherein the third photodetector is diagonal to the second photodetector;
- forming a first readout transistor on a front-side surface of the substrate, wherein the first readout transistor overlies the first photodetector and the second photodetector;
- and
- forming a second readout transistor on the front-side surface over the third photodetector, wherein a first sidewall of the first readout transistor over the first photodetector is disposed along a first plane when viewed from a top view, wherein a sidewall of the second readout transistor over the third photodetector is substantially coplanar with the first plane, and wherein a top surface of the substrate is orthogonal to the first plane.
A method for forming an image sensor, the method comprising:
- forming a shallow trench isolation (STI) structure on a front-side surface of a semiconductor substrate;
- forming a first photodetector and a second photodetector in the semiconductor substrate, wherein the first and second photodetectors are laterally separated by the STI structure;
- forming a readout transistor on the front-side surface, wherein a first sidewall of the readout transistor overlies the first photodetector and a second sidewall of the readout transistor overlies the second photodetector, wherein the first sidewall is opposite the second sidewall, and wherein the readout transistor continuously extends over an upper surface of the STI structure;
- forming first source/drain regions along the first sidewall of the readout transistor;
- forming a first junction isolation structure along the first sidewall of the readout transistor, wherein the first junction isolation structure is laterally between the first source/drain regions;
- and
- forming a deep-trench isolation (DTI) structure on a back-side surface of the semiconductor substrate, wherein the DTI structure extends from the back-side surface to the STI structure.
Dependencies are inferred from the claim text.