Trench Light Shielding for Stray Light Suppression
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Solution Overview
Problem
Existing photoelectric conversion apparatuses suffer from image quality deterioration due to stray light that is not effectively shielded by the light-shielding film, particularly when light is incident obliquely or from the end portion of the chip, leading to photoelectric conversion in the light-shielding region.
Innovation Solution
A photoelectric conversion apparatus with a semiconductor layer featuring a pixel region and a light-shielding region, where the light-shielding region includes a first and second trench structure with specific depth relationships and arrangements, forming a light attenuating wall to suppress stray light by overlapping in an orthogonal projection, thereby preventing light from entering the pixel region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light-shielding film is used to shield the light-shielding region, then vertical light incidence is blocked, but oblique stray light from end portions can still enter the pixel region and deteriorate image quality
Solution Approach 1:
The light-shielding region is divided into a first light-shielding region with trench structures and a second light-shielding region without trenches. This segmentation allows different shielding strategies: the first region uses deep trench structures to block oblique stray light, while the second region uses a simpler light-shielding film structure, optimizing both stray light suppression and manufacturing precision.
Solution Approach 2:
Different regions of the light-shielding structure are given different properties: the first light-shielding region has deep trench structures extending through the semiconductor layer to block oblique light, while the second light-shielding region uses only a light-shielding film. This local differentiation addresses the specific stray light problems in different areas without over-engineering the entire structure.
2Object-affected harmful factors
If deep trench structures are formed to block stray light, then light shielding performance improves, but the semiconductor layer strength may be compromised if trenches extend through the entire layer
Solution Approach 1:
The trench structures are segmented to extend only from the first surface to a depth not exceeding the second surface, rather than completely through the semiconductor layer. This segmentation maintains structural integrity while providing sufficient stray light blocking in the first light-shielding region.
Solution Approach 2:
Deep trench structures are localized only to the first light-shielding region where they are needed for stray light blocking, while the second light-shielding region uses only a light-shielding film without trenches. This localized approach provides maximum stray light suppression where needed while preserving semiconductor layer strength in other regions.
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 stray light, maintaining image quality and reducing chip defects, while ensuring the semiconductor layer's strength is maintained without trench structures extending through it, thus preventing a reduction in image quality.
Implementation Method 1
the first trench structure and the second trench structure overlap at least partly in an orthogonal projection orthogonal to the first surface and provided with respect to a virtual surface along a boundary between the first light-shielding region and the second light-shielding region
Data Source
AI summary
An apparatus comprising a semiconductor arranged with a pixel region and a shielding region is provided. The shielding region includes a first region having first and second trenches and a second region arranged between the first region and the pixel region. The first trench extends from a first surface of the semiconductor toward a second surface of the semiconductor and the second trench extends from the second surface toward the first surface. (D/2)≤(T1, T2)<D is satisfied, where T1 and T2 are depth of the first and second trenches and D is a thickness of the semiconductor. The first and second trenches are arranged apart from each other, and the first and second trenches overlap at least partly in an orthogonal projection with respect to a boundary surface between the first and second regions.