Guard Dams for Heat Isolation in Image Sensors
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Solution Overview
Problem
Heat generated in the logic area of image sensors can transfer to the pixel area, causing defects such as dark current, white spots, and increased resistance in interconnections, which affects the performance of high-performance stack-type image sensors used in various applications.
Innovation Solution
Incorporating a guard area with first and second guard dams between the logic and pixel areas, where the first guard dam acts as a heat insulator and the second guard dam as a heat conductor to guide heat away from the pixel area, preventing heat transfer and enhancing thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat dissipation structures are added to manage thermal effects, then heat-related defects are reduced, but device complexity increases
Solution Approach 1:
The guard area is divided into two distinct functional zones: a first guard area containing heat-blocking structures (guard rings and guard trenches filled with insulating material) and a second guard area containing heat-dissipation structures (guard trenches filled with conductive material and heat dissipation holes). This segmentation allows each zone to perform its specific thermal management function independently, effectively reducing heat-related defects while maintaining a systematic and organized structure.
Solution Approach 2:
The guard area acts as an intermediary zone between the logic area (heat source) and the pixel area (heat-sensitive region). By introducing this intermediate buffer zone with specialized thermal management structures, heat transfer from the logic area to the pixel area is significantly reduced, protecting image quality without requiring direct modification of the pixel area itself.
2Reliability
If guard dams are added to block heat transfer, then heat isolation is improved, but manufacturing complexity increases
Solution Approach 1:
The fabrication process merges multiple steps into integrated operations. The guard trenches are formed and filled with appropriate materials (insulating or conductive) in a unified process flow. The heat-blocking and heat-dissipation functions are combined within the same guard area structure, reducing the need for separate manufacturing operations and simplifying the overall fabrication process.
Solution Approach 2:
The patent utilizes parameter changes in material properties during fabrication. By selecting materials with specific thermal conductivity parameters for filling the guard trenches (insulating material for heat blocking, conductive material for heat dissipation), the structure achieves dual thermal management functions. The fabrication process leverages standard semiconductor manufacturing techniques with controlled material deposition parameters.
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 reduces heat-related defects in image sensors, improving image quality and reliability by isolating the pixel area from heat generated in the logic area, thereby enhancing the performance of high-performance stack-type image sensors.
Implementation Method 1
The first guard dam may be a heat insulator that blocks heat transfer
Implementation Method 2
The second guard dam may be a heat conductor that guides any heat which passes through the first guard dam and reaches the second guard dam away from the pixel area to an image sensor opening
Data Source
AI summary
An image sensor is described. The image sensor may include a substrate including a pixel area, a logic area, and a guard area disposed between the pixel area and the logic area. The guard area may substantially prevent transfer of heat generated in the logic area from reaching the pixel area.