Stacked Visible and Infrared Pixel Structure for Image Sensors
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Solution Overview
Problem
Current image sensors face challenges in enhancing light sensitivity and quantum efficiency for both visible and infrared light detection, particularly in designing structures and materials that can effectively capture images across various wavelength ranges within limited pixel dimensions.
Innovation Solution
The integration of a visible light detection structure and an infrared light detection structure within the same pixel region of a semiconductor substrate, where the infrared light detection structure includes an epitaxial structure and the visible light detection structure includes a doped region, optimized to improve light sensitivity and quantum efficiency by overlapping portions of the visible light detection structure between the infrared light detection structure and the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a visible light detection structure and an infrared light detection structure are disposed within the same pixel region, then light sensitivity and quantum efficiency are improved, but device complexity increases
Solution Approach 1:
The patent combines visible light detection and infrared light detection into a single pixel region, integrating two different detection functions in one location. The visible light detection structure and infrared light detection structure share the same pixel region, allowing simultaneous detection of both wavelengths without requiring separate pixel areas, thus improving light sensitivity while managing device complexity through functional integration.
Solution Approach 2:
The patent utilizes vertical stacking to arrange detection structures in different spatial dimensions. The first isolation structure extends from the first surface toward the second surface, creating vertical separation between detection regions. This three-dimensional arrangement allows multiple detection functions to coexist in the same planar pixel region by utilizing the depth dimension, thereby improving sensitivity without proportionally increasing surface complexity.
2Reliability
If multiple detection structures are integrated in the same pixel region, then quantum efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent divides the pixel region into distinct detection zones using isolation structures. The first isolation structure creates separate detection regions for visible and infrared light, allowing each detection structure to be optimized and manufactured independently with precise boundaries. This segmentation enables controlled manufacturing processes for each region while achieving high quantum efficiency through integrated operation.
Solution Approach 2:
The first isolation structure acts as an intermediary element between the visible light detection structure and infrared light detection structure. This isolation structure provides physical and electrical separation, facilitating precise manufacturing and alignment of each detection component while enabling their coordinated operation to achieve high quantum efficiency in the integrated pixel region.
3Area of stationary object
If detection structures are positioned closer together, then area is reduced, but interference between structures increases
Solution Approach 1:
The first isolation structure segments the pixel region into distinct detection zones, creating clear boundaries between visible and infrared detection areas. This segmentation allows the detection structures to be positioned closely together in the same pixel region while preventing optical and electrical interference through physical separation, thus reducing pixel area without compromising detection performance.
Solution Approach 2:
The isolation structure serves as an intermediary barrier between detection structures, blocking stray light and preventing charge carrier diffusion between adjacent regions. This intermediary element enables compact pixel design by allowing close positioning of detection structures while maintaining signal integrity and preventing cross-talk interference.
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 enhances the photoelectric conversion performance of the infrared light detection structure, improving light sensitivity and quantum efficiency while maintaining high resolution, even within constrained pixel dimensions.
Implementation Method 1
a visible light detection structure, wherein a first portion of the visible light detection structure is disposed between the infrared light detection structure and the second surface of the semiconductor substrate in the vertical direction
Implementation Method 2
The infrared light detection structure includes an epitaxial structure disposed in the semiconductor substrate
Data Source
AI summary
An image sensor includes a semiconductor substrate, a first isolation structure, a visible light detection structure, and an infrared light detection structure. The semiconductor substrate has a first surface and a second surface opposite to the first surface in a vertical direction. The first isolation structure is disposed in the semiconductor substrate for defining pixel regions in the semiconductor substrate. The visible light detection structure and the infrared light detection structure are disposed within the same pixel region, and a first portion of the visible light detection structure is disposed between the second surface of the semiconductor substrate and the infrared light detection structure in the vertical direction. The infrared light detection structure includes an epitaxial structure disposed in the semiconductor substrate, and the visible light detection structure includes a doped region including a material identical to a material of the semiconductor substrate.