Solid-State Imaging Device Pixel Concavo-Convex Structure
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Solution Overview
Problem
Existing solid-state imaging devices face challenges in achieving higher image quality and functionality due to limitations in sensitivity uniformity and contrast unevenness, particularly with oblique incident light.
Innovation Solution
A solid-state imaging device with a pixel region where each pixel includes a photoelectric conversion unit and a concavo-convex portion, with varying numbers and pitches of irregularities across the central and peripheral portions, optimized to prevent light reflection and enhance quantum efficiency by positioning concavo-convex portions strategically to cover light converging regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a concavo-convex portion is formed on the light receiving surface to improve sensitivity, then light reflection is reduced and quantum efficiency increases, but contrast unevenness occurs and sensitivity uniformity deteriorates across different pixel regions
Solution Approach 1:
The patent applies local quality by differentiating the concavo-convex portion configuration between central and peripheral pixel regions. Central pixels receive oblique light and are assigned concavo-convex portions with larger pitch values, while peripheral pixels receive substantially perpendicular light and are assigned concavo-convex portions with smaller pitch values. This localized differentiation optimizes light reflection prevention for each region's specific illumination characteristics, thereby maintaining sensitivity uniformity across the entire sensor while preserving quantum efficiency improvements.
2Reliability
If the number of irregularities in concavo-convex portions is increased to prevent light reflection, then sensitivity improves, but contrast unevenness and sensitivity non-uniformity worsen
Solution Approach 1:
The patent employs parameter changes by systematically varying the pitch values of concavo-convex portions based on pixel position. The pitch parameter is adjusted according to the incident light angle characteristics of different regions: larger pitches in central regions for oblique light, and smaller pitches in peripheral regions for perpendicular light. This parameter differentiation prevents excessive light reflection in any single region, thereby maintaining contrast uniformity while preserving overall sensitivity enhancement.
3Ease of manufacture
If a uniform concavo-convex structure is applied across all pixels, then manufacturing is simplified, but sensitivity uniformity and contrast quality deteriorate
Solution Approach 1:
The patent implements local quality by dividing the pixel array into central and peripheral regions with distinct concavo-convex portion configurations. This regional differentiation addresses the specific optical characteristics of each area: central pixels with oblique incident light receive larger pitch values, while peripheral pixels with perpendicular light receive smaller pitch values. The approach maintains manufacturing feasibility through systematic patterning while achieving superior sensitivity uniformity and contrast quality compared to a completely uniform structure.
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 improves sensitivity uniformity and reduces contrast unevenness, leading to enhanced image quality and functionality by effectively confining light and preventing light leakage between pixels.
Implementation Method 1
each of the pixels includes a photoelectric conversion unit and a concavo-convex portion... the concavo-convex portion being positioned above the photoelectric conversion unit and formed on a light receiving surface side
Implementation Method 2
a photoelectric conversion unit photoelectrically converting incident light formed on a semiconductor substrate
Data Source
AI summary
A solid-state imaging device capable of improving image quality and functionality is provided.Provided is a solid-state imaging device including a pixel region in which a plurality of pixels are two-dimensionally disposed, in which each of the pixels includes a photoelectric conversion unit and a concavo-convex portion, the photoelectric conversion unit photoelectrically converting incident light formed on a semiconductor substrate, and the concavo-convex portion being positioned above the photoelectric conversion unit and formed on a light receiving surface side of the semiconductor substrate, and the number of irregularities of a concavo-convex portion included in a pixel disposed in a central portion of the pixel region and the number of irregularities of a concavo-convex portion included in a pixel disposed in a peripheral portion of the pixel region are different from each other.