Backside Illuminated Image Sensor Heat Sink Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Complementary metal oxide semiconductor (CMOS) image sensors, particularly in back-side illumination configuration, face challenges due to light being obstructed by metal and dielectric layers and transfer transistors, leading to operational and manufacturing complexities.
Innovation Solution
Incorporating a heat sink within the metallization layers of the image sensor package to reroute heat away from the image sensor, thereby reducing thermal interference and improving image quality by maintaining uniform heat distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light passes through metal layers and dielectric layers to reach the photodiode in front-side illumination configuration, then the image sensor can capture images, but the metal layers and dielectric layers block light and cause processing and operational issues
Solution Approach 1:
The patent inverts the traditional front-side illumination configuration to a back-side illumination configuration. Light now enters through the back of the substrate and reaches the photodiode before encountering the metal layers and dielectric structures. This inversion eliminates the light blocking problem while maintaining image capture functionality.
2Ease of operation
If transfer transistors are formed adjacent to photodiodes to transfer signals at desired times, then image capture timing is controlled, but the transfer transistors and associated layers increase device complexity
Solution Approach 1:
The patent extracts the transfer transistor functionality from the traditional pixel structure and relocates it to the back side of the substrate. This separation allows the front side to be optimized for light detection while the back side handles signal transfer and processing, reducing the complexity of light path interference.
3Power
If heat is generated by adjacent semiconductor devices, then normal operation occurs, but thermal distortion affects image quality
Solution Approach 1:
The patent introduces an intermediary thermal management structure between the adjacent semiconductor devices and the image sensor. This intermediary component manages heat flow to prevent thermal distortion from affecting image quality while allowing adjacent devices to operate normally.
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 heat sink effectively manages heat generated by adjacent semiconductor devices, preventing thermal distortion and ensuring consistent image capture, thus enhancing the efficiency and reliability of the image sensor.
Implementation Method 1
The heat sink effectively manages heat generated by adjacent semiconductor devices, preventing thermal distortion and ensuring consistent image capture
Data Source
AI summary
A system and method for blocking heat from reaching an image sensor in a three dimensional stack with a semiconductor device. In an embodiment a heat sink is formed in a back end of line process either on the semiconductor device or else on the image sensor itself when the image sensor is in a backside illuminated configuration. The heat sink may be a grid in either a single layer or in two layers, a zig-zag pattern, or in an interleaved fingers configuration.