Pixel Separation Groove Structure for Low-Crosstalk Image Sensors
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Solution Overview
Problem
In solid-state imaging devices, as pixel size is reduced, crosstalk occurs due to light entering the wrong pixel, and the ratio of insulating film to photoelectric conversion section size increases, leading to deteriorated dark current characteristics.
Innovation Solution
A solid-state imaging device with a pixel separation section in a pixel separation groove, where the interface between the pixel separation section and the semiconductor substrate has a {100} plane, incorporating a thin insulating film and potentially a light shielding film, with the insulating film containing elements from the substrate and oxygen, and a thicker film thickness limited to corner portions for reduced overall film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is reduced to increase photoelectric conversion sections, then the imaging resolution is improved, but crosstalk occurs between pixels and the ratio of insulating film size to photoelectric conversion section size increases
Solution Approach 1:
The pixel separation section is designed with non-uniform insulating film thickness, where the film is thinner at the center and thicker at the corner portions. This local variation in quality allows the insulating film to provide adequate isolation at corners while maintaining a smaller overall pixel separation section size, thereby reducing crosstalk without excessively reducing the photoelectric conversion section area.
Solution Approach 2:
The pixel separation section extends in the depth direction (thickness direction) with varying film thickness, creating a three-dimensional structure. By making the insulating film thicker at corner portions and thinner at the center, the solution addresses crosstalk isolation needs in the vertical dimension while allowing horizontal pixel dimensions to be optimized for resolution.
2Area of moving object
If the insulating film thickness is reduced to decrease the pixel separation section size, then the photoelectric conversion section size is improved, but the dark current characteristics deteriorate
Solution Approach 1:
The insulating film thickness is optimized locally: thinner at the center to maximize photoelectric conversion section area, and thicker at corner portions to maintain adequate isolation and dark current characteristics. This local differentiation allows the system to achieve both goals simultaneously.
Solution Approach 2:
The insulating film thickness parameter is varied across different spatial locations within the pixel separation section. By changing the thickness parameter from uniform to non-uniform distribution, the design achieves optimal balance between photoelectric conversion efficiency and dark current suppression.
3Area of moving object
If the pixel separation section size is reduced to increase the photoelectric conversion section area, then the imaging performance is improved, but the isolation between pixels is insufficient
Solution Approach 1:
The pixel separation section utilizes the depth dimension by creating a non-uniform insulating film thickness profile. The thicker regions at corner portions provide enhanced light isolation in the vertical dimension, compensating for the reduced horizontal separation distance and preventing light leakage while allowing larger photoelectric conversion sections.
Solution Approach 2:
The pixel separation section employs a composite structure with the insulating film having spatially varying thickness, combining regions of different optical isolation strength. This composite approach allows the overall structure to provide sufficient light blocking despite a reduced total size, enabling larger photoelectric conversion sections.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for suitable formation of the pixel separation section, reducing its size and improving dark current characteristics by minimizing the insulating film thickness and optimizing the light shielding film, thus addressing crosstalk and performance issues.
Implementation Method 1
the insulating film may contain an element contained in the first semiconductor substrate and oxygen. Thus, for example, the insulating film can be formed by oxidizing the side surface of the first semiconductor substrate
Data Source
AI summary
Provided is a solid-state imaging device capable of suitably forming a pixel separation section in a pixel separation groove, and a method for manufacturing the solid-state imaging device.A solid-state imaging device of the present disclosure includes a first substrate, a plurality of photoelectric conversion sections provided in the first substrate, and a pixel separation section provided between the photoelectric conversion sections in the first substrate and provided on a side surface of the first substrate that is a {100} plane.