Stacked Color Image Sensor Phase Alignment
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Solution Overview
Problem
The hybrid photoelectric conversion layer stack type color solid-state image sensing device experiences conspicuous false color issues at the peripheries of the photo acceptance portions due to significant phase differences between green and red signal images, particularly exacerbated by oblique light incidence.
Innovation Solution
The device is designed with unit cells arranged two-dimensionally on a silicon substrate, featuring a blue pixel as a photodiode on the surface, a red pixel beneath the blue pixel, and a green pixel as a photoelectric conversion layer stacked above, with micro lenses and a light blocking layer to adjust the position and alignment of the green pixel relative to the red pixel, ensuring the condition P≧W to minimize phase differences and false color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photoelectric conversion layer is stacked above the silicon substrate to detect green light, then green light detection capability is improved, but phase differences between green and red signal images occur causing false color at peripheries
Solution Approach 1:
The patent transitions from a planar two-dimensional pixel arrangement to a three-dimensional stacked structure where blue photodiodes are in the silicon substrate, green photoelectric conversion layers are stacked above, and red photodiodes are beneath. This vertical stacking enables green light detection while requiring precise control of the distance W to maintain phase alignment and avoid false color at peripheries.
Solution Approach 2:
The patent establishes a specific parameter relationship P≧W where P is the pixel pitch and W is the distance between the green photoelectric conversion layer and red photodiode. By controlling this distance parameter, the patent ensures that phase differences between green and red signals remain below 90 degrees, preventing false color while maintaining high-resolution color imaging capability.
2Manufacturing precision
If micro lenses and light blocking layers are added to adjust green pixel position, then false color is reduced, but device structure and manufacturing complexity increase
Solution Approach 1:
The patent introduces micro lenses and light blocking layers as intermediary optical elements to control and adjust the optical path and position of green light detection. These intermediaries enable precise phase alignment between green and red signals, reducing false color while integrating into the existing stacked photoelectric conversion 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
This configuration effectively reduces false color in the periphery of the photo acceptance area, enabling high-resolution and high-quality color imaging by maintaining phase differences below 90 degrees, thus suppressing conspicuous false color.
Implementation Method 1
blue light is detected by photodiodes provided in a semiconductor substrate
Implementation Method 2
green light is detected by a photoelectric conversion layer stacked on the semiconductor substrate
Implementation Method 3
red light is detected by photodiodes provided in a semiconductor substrate
Data Source
AI summary
A color solid-state image sensing device comprising unit cells arranged two-dimensionally in a surface of a silicon substrate, each unit cell including a blue pixel provided as defined herein, a red pixel as defined herein and a green pixel as defined herein, wherein the relation P≧W holds when W is a distance between the position of the center of gravity in a sensitivity distribution of the green pixel and the position of the center of gravity in a sensitivity distribution of the red pixel, and P is a pitch of arrangement of the unit cells.