Image Sensor Passivation Structure for Groove Corrosion Protection
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Solution Overview
Problem
Current image sensors face challenges in productivity and reliability due to issues with passivation layer step coverage, leading to potential corrosion and reduced performance.
Innovation Solution
The image sensor design incorporates a second passivation layer with higher step coverage than the first passivation layer, specifically formed to cover the groove portions of the first passivation layer, enhancing protection against moisture and improving the overall reliability and endurance of the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a first passivation layer is formed on the conductive layer, then the conductive layer is protected, but groove portions are exposed and susceptible to corrosion
Solution Approach 1:
The second passivation layer is selectively formed to cover only the groove portions of the first passivation layer, providing localized protection where it is most needed. This local quality approach ensures that the exposed groove portions are protected from corrosion without requiring a complete redesign of the entire passivation structure.
Solution Approach 2:
The solution introduces a vertical dimension by forming a second passivation layer that extends into the groove portions from above. This dimensional approach allows the groove portions to be covered and protected while maintaining the original first passivation layer structure on the surface.
2Reliability
If multiple passivation layers are added to improve protection, then reliability improves, but manufacturing complexity increases
Solution Approach 1:
The passivation structure is segmented into two distinct layers with different functions: the first passivation layer provides general protection, while the second passivation layer specifically targets and protects the groove portions. This segmentation allows each layer to be optimized for its specific purpose, improving overall reliability without excessive complexity.
Data Source
AI summary
An image sensor includes a chip structure including first and second regions. The chip structure further includes a substrate having a first surface, a second surface, and a recess portion, a plurality of photoelectric conversion devices included in the substrate, at least one conductive layer on a sidewall and a bottom surface of the recess portion and on the horizontal insulating layer in the second region, a first passivation layer on a side surface of the conductive layer in the recess portion and the conductive layer on the horizontal insulating layer, and a second passivation layer on side surface of the first passivation layer in the recess portion.