Stacked Image Sensor Layout for Optical Black Charge Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In laminated photoelectric conversion apparatuses, excess charges from the periphery of the optical black (OB) region can mix with the OB region, leading to inaccurate black level reference signal detection and pixel value correction.
Innovation Solution
A photoelectric conversion apparatus is designed with a first semiconductor device layer containing an effective pixel region, an optical black pixel region, and an outer periphery region, where a light-blocking layer overlaps only the optical black pixel region and not the outer periphery region, and a charge draining region with the same conductivity type as the signal charge is provided in the outer periphery region to prevent excess charge mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge draining pixels are disposed between the effective pixel region and the OB region to drain signal charges leaking from the effective pixel region, then signal charge leakage is prevented, but signal processing circuits cannot be placed in the periphery of the OB region leading to increased device complexity
Solution Approach 1:
The patent segments the region between the effective pixel region and the OB region into two distinct functional zones: an optical black pixel region for receiving leaked signal charges and an outer periphery region for placing signal processing circuits. This segmentation allows each region to serve its specific function without interference, resolving the contradiction between preventing charge leakage and accommodating circuit placement.
Solution Approach 2:
The patent applies different properties to different regions: the optical black pixel region is designed to receive and drain signal charges from the effective pixel region, while the outer periphery region is designed to place signal processing circuits. This local differentiation of function and property allows the system to simultaneously achieve charge leakage prevention and circuit integration.
2Device complexity
If OB pixels are placed in the end portion of the substrate to simplify structure, then device complexity is reduced, but signal charges generated in the periphery of the OB region mix into the OB region causing black level reference signal fluctuation
Solution Approach 1:
The patent introduces an outer periphery region as an intermediary zone between the optical black pixel region and the end portion of the substrate. This intermediary region acts as a buffer that prevents signal charges generated in the periphery from mixing into the OB region, thereby protecting the black level reference signal accuracy while maintaining structural simplicity.
Solution Approach 2:
The patent creates distinct functional zones with different properties: the optical black pixel region for accurate black level reference detection, the outer periphery region for circuit placement and charge generation, and the optical black pixel region serving as a protective barrier. This local quality differentiation ensures that charge generation in the periphery does not affect OB region measurements.
3Reliability
If a light-blocking layer is extended to cover the outer periphery region to prevent excess charge mixing, then charge contamination is prevented, but light-blocking material is increased leading to higher device complexity
Solution Approach 1:
The patent extracts the light-blocking function from the outer periphery region and relocates it to the optical black pixel region. By taking out the light-blocking requirement from the circuit placement area, the patent allows signal processing circuits to be placed in the outer periphery region without excessive charge mixing, reducing overall device complexity while maintaining charge prevention through the optical black pixel region's light-blocking properties.
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 prevents excess charge mixing in the OB region, allowing for more accurate detection of black level reference signals and proper correction of pixel values in the effective pixel region.
Implementation Method 1
a light-blocking region formed by a light-blocking layer overlaps the optical black pixel region
Implementation Method 2
the outer periphery region has a charge draining region including a semiconductor region of the same conductivity type as a signal charge, and a fixed potential is supplied to the charge draining region
Implementation Method 3
a first semiconductor device layer including a plurality of photoelectric conversion units
Data Source
AI summary
A photoelectric conversion apparatus includes a first substrate having a first semiconductor device layer including a plurality of photoelectric conversion units and a well, and a second substrate having a second semiconductor device layer including a circuit configured to process signals obtained by the plurality of photoelectric conversion units, wherein the first and second substrates are laminated together, wherein the first semiconductor device layer includes an effective pixel region, an optical black pixel region, and an outer periphery region, wherein, in a planar view, a light-blocking region formed by a light-blocking layer overlaps the optical black pixel region, and the light-blocking region does not overlap the outer periphery region, wherein the outer periphery region has a charge draining region including a semiconductor region of the same conductivity type as a signal charge, and wherein a fixed potential is supplied to the charge draining region.