Nano Void Gettering for Image Sensor Contamination Control
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Solution Overview
Problem
Heavy metal contamination of photodiodes and their surrounding regions in image sensors adversely affects performance and lifespan, necessitating an effective control mechanism.
Innovation Solution
The integration of nano void regions with varying densities of nano voids adjacent to photodiodes in the substrate, formed through ion implantation and thermal treatment, acts as a getter to collect and manage heavy metal contaminants, thereby preventing contamination and enhancing image sensor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photodiode structures are used without additional contamination control mechanisms, then device complexity is low, but heavy metal contamination adversely affects performance and lifespan
Solution Approach 1:
The patent introduces nano void regions with varying densities of nanoscale voids adjacent to photodiodes. These porous structures act as getters to collect and trap heavy metal contaminants, preventing them from reaching and contaminating the photodiode active regions, thereby improving reliability without significantly complicating the overall device architecture
Solution Approach 2:
The patent implements non-uniform density distributions of nano voids, with higher density regions positioned closer to the photodiodes and lower density regions farther away. This local variation in void density optimizes the gettering effect near the photodiodes while maintaining structural integrity in surrounding areas, addressing contamination control where it is most needed
2Object-affected harmful factors
If nano void regions with varying densities are introduced to control heavy metal contamination, then contamination control improves, but device complexity increases
Solution Approach 1:
The patent utilizes nano void regions with controlled porosity to create gettering zones that attract and trap heavy metal contaminants. The varying density of nano voids within these regions enhances the contamination control effectiveness by creating gradient fields that guide contaminants away from photodiodes
Solution Approach 2:
The nano void regions are formed and positioned adjacent to photodiodes before heavy metal contamination can occur during device operation. This preliminary structural arrangement proactively prevents contamination by establishing gettering zones in advance, rather than attempting to remove contaminants after they have accumulated
3Ease of manufacture
If uniform density of nano voids is used throughout the nano void region, then manufacturing process is simpler, but contamination control effectiveness is reduced
Solution Approach 1:
The patent employs non-uniform density distribution of nano voids within the nano void regions, with higher density zones positioned closer to photodiodes where contamination risk is greatest. This local variation in void density optimizes the gettering effect at critical interfaces while maintaining fabrication feasibility through controlled gradient structures
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 nano void regions effectively control heavy metal contamination, improving the image sensor's performance and lifespan by reducing defects and crosstalk between pixels, and maintaining high efficiency throughout the sensor's operational life.
Implementation Method 1
nano void regions formed in the substrate adjacent to sides of each photodiode... acts as a getter to collect and manage heavy metal contaminants
Implementation Method 2
formed through ion implantation and thermal treatment
Data Source
AI summary
An image sensor includes a plurality of photodiodes formed in a substrate; nano void regions formed in the substrate adjacent to sides of each photodiode of the plurality of photodiodes; and a plurality of nano voids formed in each nano void region of the nano void regions.