Pixel Light-Receiving Layout for Symmetric Transfer and Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In solid-state imaging devices, the annular shape of the transfer gate electrode surrounding the floating diffusion region makes it difficult to extract light efficiently due to reduced optical symmetry and challenges in fixing the potential of the well region, affecting signal transfer efficiency and sensitivity.
Innovation Solution
A light receiving element and solid-state imaging device design where transfer gate electrodes are spaced apart and arranged symmetrically around the floating diffusion region with a gate insulating film, allowing for improved optical symmetry and efficient light extraction, while maintaining the potential of the well region through a grounded semiconductor region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a transfer gate electrode is arranged in an annular shape surrounding the floating diffusion region, then the distance between the photoelectric conversion region and transfer gate electrode is shortened improving transfer efficiency, but optical symmetry is reduced making it difficult to extract light efficiently
Solution Approach 1:
The annular transfer gate electrode is divided into multiple discrete transfer gate electrodes arranged in a circular pattern around the floating diffusion region. This segmentation maintains the compact circular layout for efficient signal transfer while allowing light to pass through the gaps between individual electrodes, preserving optical symmetry and improving light extraction efficiency.
2Quantity of substance
If a transfer gate electrode is arranged in an annular shape surrounding the floating diffusion region, then the area of the photoelectric conversion region can be expanded improving sensitivity, but the well region cannot be easily taken out making it difficult to fix the potential
Solution Approach 1:
The well region is extracted or taken out from beneath the annular transfer gate electrode structure by forming it in the semiconductor substrate at positions not occupied by the transfer gate electrodes. This allows the well region to be separately formed and connected to a potential fixing electrode, enabling independent potential control while maintaining the expanded photoelectric conversion region area.
3Ease of operation
If a portion of the annular transfer gate electrode is cut out to take out the well region, then the well region can be accessed for potential fixing, but optical symmetry is further reduced affecting light extraction
Solution Approach 1:
Rather than cutting out portions from a continuous annular electrode, the transfer gate function is achieved through multiple discrete segmented electrodes arranged in a circle. The well region is accessed through the natural gaps between these segments, eliminating the need for additional cutouts and preserving optical symmetry for efficient light extraction.
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 design enhances signal transfer efficiency and sensitivity by maintaining optical symmetry and allowing for efficient light extraction, improving the overall performance of the solid-state imaging device.
Implementation Method 1
a photoelectric conversion region that constitutes a pixel
Data Source
AI summary
Provided is a light-receiving element having a structure in which a floating diffusion region is surrounded by transfer gate electrodes in a single photoelectric conversion region constituting a pixel, the structure making it possible to improve optical symmetry and to extract light efficiently. The light-receiving element comprises: a photoelectric conversion region constituting a pixel; a floating diffusion region of a first electrical conductivity type provided on one main surface side of the photoelectric conversion region; and a plurality of transfer gate electrodes which are provided on the one main surface side of the photoelectric conversion region and are spaced apart from each other with a gate insulating film therebetween, the plurality of transfer gate electrodes being provided symmetrically about the floating diffusion region in a planar pattern.