Through Via Structure for BSI Image Sensor Isolation
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Solution Overview
Problem
Backside illuminated (BSI) image sensor devices suffer from cross-talk and blooming issues due to insufficient isolation between neighboring pixels, leading to leakage currents that degrade the reliability of the semiconductor device.
Innovation Solution
The implementation of a through via (TOV) structure that connects metallic structures across semiconductor chips, directing electrons to ground and reducing leakage current by electrically interconnecting the chips through a conductive material-filled trench.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transistor device size is shrunk with each technology generation, then device integration density is improved, but cross-talk and blooming issues occur due to insufficient isolation between neighboring pixels
Solution Approach 1:
The patent introduces a vertical dimension by forming a trench that extends through multiple layers (first dielectric structure, substrate, second dielectric structure, passivation structure) to create deep isolation regions. This vertical penetration provides enhanced electrical isolation between pixels in the lateral direction, solving the cross-talk issue while maintaining high integration density.
Solution Approach 2:
The patent segments the semiconductor structure by dividing it into distinct regions separated by the trench filled with conductive material. The trench creates discrete isolation zones between neighboring pixels, allowing each pixel to be electrically independent while maintaining compact lateral spacing for high integration density.
2Ease of manufacture
If existing BSI image sensor device structures are used, then manufacturing simplicity is maintained, but leakage current occurs due to insufficient electron direction to ground
Solution Approach 1:
The patent introduces an intermediary conductive material filled trench that acts as a mediator to direct electrons to ground. The trench filled with conductive material serves as an intermediate pathway that efficiently channels leakage electrons from the pixel region to the ground, preventing blooming while integrating into the existing BSI sensor manufacturing process.
3Reliability
If metallic structures are interconnected across semiconductor chips, then electrical connection is improved, but device complexity increases due to additional through via structure
Solution Approach 1:
The trench structure serves multiple functions simultaneously: it provides electrical isolation between pixels through its depth, directs leakage electrons to ground through the conductive fill, and enables inter-chip electrical connection. This multi-functionality reduces the need for separate structures, effectively managing complexity while achieving multiple reliability goals.
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 TOV structure effectively reduces leakage current by ensuring electrons are directed to ground, thereby enhancing the reliability and performance of BSI image sensor devices by improving electrical isolation between pixels.
Implementation Method 1
directing electrons to ground and reducing leakage current by electrically interconnecting the chips through a conductive material-filled trench
Data Source
AI summary
A semiconductor device includes a first dielectric structure, a second dielectric structure, a first substrate between the first dielectric structure and the second dielectric structure, a passivation structure over the second dielectric structure, a first metallic structure over the first dielectric structure, a second metallic structure over the passivation structure, and a third metallic structure in the first and second dielectric structures, the first substrate, and the passivation structure. The second dielectric structure is between the passivation structure and the first substrate. The first metallic structure is electrically connected to the second metallic structure through the third metallic structure, the third metallic structure includes a first portion in the first dielectric structure and the first substrate, a second portion in the second dielectric structure and a third portion in the passivation structure. Widths of the first portion, the second portion and the third portion are different from each other.