Backside Image Sensor TSV Edge Sealing Against Contamination
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Solution Overview
Problem
Backside illumination image sensors face challenges in enhancing light receiving efficiency and preventing contamination at the through-silicon-via (TSV) interface, particularly due to issues with moisture, mobile ions, and hydrogen ingress.
Innovation Solution
The implementation of a TSV edge seal ring, which can be made of tungsten and physically isolated from the metal landing pad, surrounds the TSV in the contact layer, extending to a depth coextensive with the TSV, and is directly coupled to diffusion barrier layers and shallow-trench-isolation regions to create a barrier against contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a through-silicon-via (TSV) is formed to extend through the die to the metal landing pad, then signal transmission and electrical connection are improved, but contamination from moisture, mobile ions, and hydrogen ingress occurs at the TSV interface
Solution Approach 1:
An edge seal ring is introduced as an intermediary component between the TSV and the surrounding environment. This seal ring acts as a barrier that prevents moisture, mobile ions, and hydrogen from reaching the TSV interface, while not interfering with the electrical signal transmission function of the TSV itself.
Solution Approach 2:
The edge seal ring is positioned to preemptively block contaminant pathways before contamination can occur. By sealing the TSV interface region in advance, the structure prevents harmful factors from penetrating into the TSV, thereby protecting the electrical connection integrity.
2Reliability
If the TSV extends deeply into the die to reach the metal landing pad, then electrical connection is improved, but the risk of contamination and structural defects increases
Solution Approach 1:
The edge seal ring serves as a protective intermediary that shields the deep TSV structure from environmental contaminants. This allows the TSV to extend deeply for reliable electrical connection without being vulnerable to moisture and ion ingress that would compromise structural integrity.
Solution Approach 2:
The seal ring provides preemptive protection against contamination that could cause structural defects. By establishing this barrier before contamination occurs, the design cushions the deep TSV structure from potential damage during operation and testing.
3Ease of manufacture
If the TSV interface is exposed to improve manufacturing simplicity, then manufacturing ease is improved, but light receiving efficiency deteriorates due to contamination
Solution Approach 1:
The edge seal ring acts as a protective intermediary that maintains the TSV interface sealing without adding significant manufacturing complexity. It prevents contamination that would reduce light receiving efficiency, while the manufacturing process remains relatively straightforward by integrating the seal ring into existing TSV formation steps.
Data Source
AI summary
Implementations of image sensor devices may include a through-silicon-via (TSV) formed in a backside of an image sensor device and extending through a material of a die to a metal landing pad. The metal landing pad may be within a contact layer. The devices may include a TSV edge seal ring surrounding a portion of the TSV in the contact layer and extending from a first surface of the contact layer into the contact layer to a depth coextensive with a depth of the TSV.