Image Sensor Recess Gate Photocharge Transfer Optimization
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Solution Overview
Problem
Current image sensing devices face challenges in achieving high photocharge transfer efficiency and reducing noise, particularly due to variations in recess gate depth and second photoelectric conversion region thickness across unit pixels, leading to inconsistent image quality.
Innovation Solution
The implementation of a second photoelectric conversion region disposed between the recess gate and the first photoelectric conversion region, with adjustable thickness and doping, to enhance photocharge transfer efficiency by shortening the distance between the photoelectric conversion regions and the recess gates, thereby improving image sensing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second photoelectric conversion region is added between the recess gate and the first photoelectric conversion region, then photocharge transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The photoelectric conversion region is divided into two separate regions: a first photoelectric conversion region and a second photoelectric conversion region. The second region is positioned between the recess gate and the first region to facilitate more efficient photocharge transfer. This segmentation allows optimization of charge transfer pathways while maintaining functional separation.
Solution Approach 2:
The second photoelectric conversion region is added in the vertical dimension between the recess gate and the first photoelectric conversion region. This three-dimensional arrangement creates an intermediate zone that improves charge transfer efficiency without increasing lateral device footprint, effectively utilizing the vertical space for enhanced performance.
2Reliability
If the thickness of the second photoelectric conversion region is reduced to improve photocharge transfer efficiency, then transfer efficiency increases, but manufacturing precision requirements increase
Solution Approach 1:
The thickness of the second photoelectric conversion region is optimized within a specific range (50-200 nm) to achieve the best balance between photocharge transfer efficiency and manufacturing feasibility. This parameter optimization allows sufficient thinness for efficient charge transfer while remaining within controllable manufacturing tolerances for semiconductor fabrication processes.
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 increases photocharge transfer efficiency and reduces noise, ensuring consistent and improved image quality across unit pixels by optimizing the distance and thickness of the second photoelectric conversion regions relative to the recess gates.
Implementation Method 1
a second photoelectric conversion region disposed between the recess gate and the first photoelectric conversion region
Data Source
AI summary
A method for manufacturing an image sensing device includes forming a first photoelectric conversion region in a semiconductor substrate, forming a recess region to extend in a direction from a surface of the semiconductor substrate toward an inside of the semiconductor substrate, arranging a mask in a portion of the recess region, forming a second photoelectric conversion region through the recess region, and forming a recess gate in the recess region. A thickness of the second photoelectric conversion region is based on a depth of the recess gate that is measured from the surface of the semiconductor substrate to a bottom surface of the recess gate.