Image Sensor Package Protective Layer Segmentation for Thermal Stress
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Solution Overview
Problem
The existing image sensor packages with stacked semiconductor substrates face issues due to thermal expansion differences between the protective layer and the substrate, leading to cracks or breakage of the protective layer during manufacturing, especially when a bonding structure is applied over the penetration electrode region.
Innovation Solution
A protective layer divided into multiple cells is applied over the penetration electrode region, which covers the surfaces of the penetration electrodes and is positioned between the bonding structure and the substrate, dispersing stress and preventing damage from thermal expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is applied over the penetration electrode region, then the penetration electrodes are protected, but cracks or breakage occur in the protective layer due to thermal expansion differences
Solution Approach 1:
The protective layer is divided into multiple separate protective layers, each covering a portion of the penetration electrode region. This segmentation allows each individual protective layer to accommodate thermal expansion independently, preventing crack propagation that would occur in a single continuous layer.
2Ease of manufacture
If a bonding structure is applied over the penetration electrode region, then electrical connection between substrates is enabled, but the protective layer breaks due to stress from thermal expansion differences
Solution Approach 1:
The protective layer is divided into multiple separate protective layers corresponding to different bonding structures. This allows the protective layer to flex and accommodate thermal stress independently in each region, preventing breakage while maintaining bonding functionality.
Solution Approach 2:
The divided protective layer acts as an intermediary between the substrate and the bonding structure, absorbing and distributing thermal expansion stress to prevent transmission of harmful stresses to the bonding interface.
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 divided protective layer effectively prevents cracks and breakage, ensuring the integrity of the image sensor package by dispersing stress caused by thermal expansion differences, thereby enhancing the reliability and durability of the image sensor package.
Implementation Method 1
due to a difference in coefficient of thermal expansion (CTE) between the protective layer and the semiconductor substrate, cracks may occur in the protective layer or the protective layer may be broken
Data Source
AI summary
An image sensor includes: a first structure including a first side, a second side opposite to the first side, a pixel region where a plurality of pixels are disposed, and a penetration electrode region disposed adjacent to the pixel region; a second structure in which a driving circuit for driving the plurality of pixels is disposed, and stacked on the second side of the first structure; a plurality of penetration electrodes that penetrate the first structure and the second structure to electrically connect the first structure and the second structure to each other, and are disposed in the penetration electrode region; and a protective layer that is disposed on the plurality of penetration electrodes, and divided into a plurality of cells, wherein the protective layer covers the penetration electrode region.