Vertical CMOS Image Sensor With Ion Implantation Isolation
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Solution Overview
Problem
Horizontal type CMOS image sensors face challenges in optimizing the process of forming photodiodes and transistors, leading to increased pixel size, reduced resolution, and poor sensitivity due to the need for shallow junctions and additional on-chip functions.
Innovation Solution
A vertical integration of circuitry and photodiodes is implemented, using a crystalline semiconductor layer with ion implantation isolation layers to minimize defects, prevent dark current, and enhance bondability and alignment, allowing for improved sensitivity and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If extra on-chip functions are added to an image sensor, then functionality is improved, but pixel size increases
Solution Approach 1:
By stacking the photodiode substrate vertically above the transistor substrate, the patent creates a three-dimensional integrated structure that reduces the horizontal footprint of each pixel. This vertical integration allows multiple functions to be packed into a smaller pixel area while maintaining all necessary on-chip functions
2Adaptability or versatility
If pixel size increases to accommodate extra functions, then functionality is improved, but resolution decreases
Solution Approach 1:
The vertical stacking architecture enables high-density integration by utilizing the third dimension (depth) rather than expanding horizontally. This allows multiple functional elements to be stacked vertically within each pixel, maintaining small pixel dimensions and thereby preserving high image resolution while accommodating comprehensive on-chip functionality
3Productivity
If photodiode area decreases to maintain pixel size, then pixel density is improved, but sensitivity deteriorates
Solution Approach 1:
The patent forms the photodiode in a separate crystalline substrate that is bonded vertically to the transistor substrate. This vertical configuration allows the photodiode to extend deeper into the substrate, increasing its light-sensitive volume and area without expanding the horizontal pixel footprint. Consequently, pixel density is maintained while sensitivity is enhanced through the increased photodiode volume
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 vertical integration of circuitry and photodiodes in CMOS image sensors achieves high sensitivity and resolution, minimizes defects, and optimizes pixel-to-pixel isolation, thereby improving image sensor performance.
Implementation Method 1
an ion implantation isolation layer in the photodiode
Data Source
AI summary
Embodiments relate to an image sensor and a method of manufacturing an image sensor. According to embodiments, an image sensor may include a first substrate, a photodiode, and an ion implantation isolation layer. According to embodiments, circuitry including a metal interconnection may be disposed over the first substrate. A photodiode may be provided in a crystalline semiconductor layer bonded to the first substrate, and electrically connected to the metal interconnection. The ion implantation isolation layer may be provided in the photodiode.