Imaging Sensor Groove Sidewalls for Flare Suppression
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Solution Overview
Problem
Solid-state imaging devices experience flare due to reflected incident light from the groove portion's side wall or bottom surface, which is then reflected by the cover glass or imaging lens, causing unnecessary light to enter the pixel region.
Innovation Solution
A solid-state imaging device with a substrate featuring a groove portion on its light-receiving surface, where the side wall surface protrudes inward in the groove's width direction, and includes recessed and projecting portions to diffuse and attenuate incident light, preventing flare by directing reflected light away from the pixel region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a groove portion is provided on the substrate to stop film peeling and cracking, then structural reliability is improved, but flare is caused by reflected light from the groove surfaces
Solution Approach 1:
The groove portion is configured with a curved bottom surface instead of a flat surface. This curvature causes incident light to be reflected in multiple directions rather than being reflected back toward the pixel region, thereby suppressing flare while maintaining the groove's structural function of preventing film peeling and cracking
Solution Approach 2:
The groove portion extends in the depth direction from the light-receiving surface, creating a three-dimensional structure. By controlling the depth and curvature of the groove, light reflection is redirected away from the pixel region, suppressing flare while preserving the groove's structural reliability function
2Ease of manufacture
If the groove portion has a simple shape, then manufacturing is easier, but light reflection causes flare
Solution Approach 1:
The curved bottom surface of the groove can be formed using standard semiconductor manufacturing techniques such as isotropic etching or by incorporating curvature in the mask design. This approach adds minimal manufacturing complexity while effectively suppressing flare through controlled light reflection
3Object-generated harmful factors
If the groove portion is deep, then flare is suppressed by redirecting light, but manufacturing precision becomes more difficult
Solution Approach 1:
The curved bottom surface design allows for effective flare suppression at moderate groove depths. The curvature radius can be optimized to achieve sufficient light redirection without requiring excessively deep grooves, thereby maintaining manufacturability and precision within standard fabrication capabilities
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
The solution effectively suppresses flare by diffusing and attenuating incident light within the groove portion, improving image quality by reducing unwanted light entry into the pixel region.
Implementation Method 1
recessed and projecting portions provided inside the groove portion
Implementation Method 2
reflected incident light is reflected by a cover glass or an imaging lens
Data Source
AI summary
A solid-state imaging device includes a substrate on which a plurality of photoelectric conversion units has been formed, a groove portion provided on a side of a light-receiving surface of the substrate, and recessed and projecting portions provided on a side wall surface of the groove portion facing a side of the plurality of photoelectric conversion units.