Photodetector Pixel-Edge Structure for Flare Suppression
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Solution Overview
Problem
Existing photodetection devices suffer from flare due to light reflection from the scribe region, which can enter the pixel region and cause image quality degradation.
Innovation Solution
A photodetection device with a semiconductor substrate featuring a groove portion and a protruding portion surrounded by a covering film with lower reflectance than the substrate, designed to reduce light reflection and scatter incident light, along with an uneven structure on the sidewall to prevent flare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a groove portion is provided between the scribe region and pixel region to reduce reflected light, then flare is reduced, but light incident on the scribe region upper surface is still reflected and may enter the pixel region
Solution Approach 1:
The invention extracts and removes the scribe region from the light path by forming a groove portion that extends from the back surface to the front surface of the semiconductor substrate. This groove physically separates the scribe region from the pixel region, preventing reflected light from the scribe region upper surface from entering the pixel region and causing flare.
Solution Approach 2:
The groove portion acts as an intermediary structure between the scribe region and pixel region. By filling the groove with a material having different refractive index than the surrounding semiconductor substrate, it mediates the light path and prevents direct reflection from the scribe region upper surface from reaching the pixel region.
2Object-affected harmful factors
If an uneven structure is provided on the groove sidewall to reduce reflected light, then flare is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The invention forms an uneven structure on the groove sidewall that scatters reflected light. This can be achieved by creating curved or non-planar sidewall surfaces that redirect reflected light away from the pixel region, reducing flare while maintaining a manufacturable structure through standard semiconductor processing techniques.
3Object-affected harmful factors
If the groove portion extends along all sides of the pixel region, then flare prevention is maximized, but the distance requirements and manufacturing constraints increase
Solution Approach 1:
The invention applies different groove configurations to different sides of the pixel region based on local requirements. Sides with longer distances to the scribe region may have shallower or absent grooves, while sides with shorter distances require deeper grooves. This localized approach maintains effective flare prevention while accommodating manufacturing variations and reducing overall complexity.
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 minimizes flare by reducing light reflection and entry into the pixel region, enhancing image quality and reducing manufacturing costs through the use of existing film formation processes.
Implementation Method 1
a covering film that covers an entire region of a surface on a light incident surface side of the protruding portion on at least one side of the plurality of sides. The reflectance of the covering film may be lower than the reflectance of the semiconductor substrate.
Implementation Method 2
an uneven structure is provided on a sidewall surface of the groove portion to reduce reflected light from the sidewall surface of the groove portion
Data Source
AI summary
Flare due to light incident on an outer peripheral side of a pixel region is to be prevented.A photodetection device includes a semiconductor substrate having a pixel region in which a plurality of pixels that perform photoelectric conversion is disposed. The semiconductor substrate includes: a groove portion that is disposed on the outer peripheral side of the pixel region, has a smaller height than the height of the pixel region, and extends along a plurality of sides; a protruding portion that is provided on the outer peripheral side of the groove portion, has a greater height than the height of the groove portion, and extends along the plurality of sides; and a covering film that covers the entire region of the surface on the light incident surface side of the protruding portion on at least one side of the plurality of sides.