TSV Image Sensor Structure for Humidity-Stress Reliability
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Solution Overview
Problem
Existing image sensing devices face challenges in achieving high reliability, particularly in withstanding temperature and humidity stress, due to exposure of through silicon via (TSV) structures outside the substrate.
Innovation Solution
The image sensing device incorporates a through silicon via (TSV) structure design where the upper end is located lower than the substrate surface, enclosed by the through hole and a passivation layer, preventing exposure to external moisture and temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the TSV structure is exposed outside the substrate to enable electrical connection between layers, then electrical connectivity is achieved, but reliability under temperature and humidity stress deteriorates
Solution Approach 1:
The TSV structure is nested within the substrate by positioning its upper end at a height lower than the substrate surface, enclosing it within the substrate volume rather than exposing it externally. This nesting approach protects the TSV from environmental harm factors while maintaining its electrical connection function.
Solution Approach 2:
A passivation layer is introduced as an intermediary element that covers the TSV structure. This passivation layer acts as a protective barrier between the TSV and the external environment, preventing direct exposure to moisture and temperature changes while allowing the TSV to maintain its electrical connectivity function.
2Ease of manufacture
If the TSV upper end is positioned at substrate surface level for easy connection, then ease of manufacture is improved, but resistance to humidity stress deteriorates
Solution Approach 1:
The TSV upper end is positioned within the substrate volume rather than at the surface, nesting it protected within the substrate structure. This positioning maintains ease of connection through the substrate while simultaneously providing protection against humidity stress.
Solution Approach 2:
The passivation layer serves as an intermediary protective barrier that covers the TSV structure, enabling the TSV to be positioned optimally for connection while protecting it from humidity exposure during operation.
3Reliability
If the TSV structure extends to the substrate surface for electrical connection, then electrical connectivity between layers is achieved, but resistance to temperature stress deteriorates
Solution Approach 1:
The TSV structure is nested within the substrate by positioning its upper end below the substrate surface. This configuration reduces exposure to temperature variations while maintaining electrical connectivity, thereby improving resistance to temperature stress without significantly increasing device complexity.
Solution Approach 2:
The passivation layer acts as an intermediary thermal barrier that covers the TSV structure, reducing direct thermal exposure and improving resistance to temperature stress while maintaining the TSV's electrical connection function.
Data Source
AI summary
An image sensing device includes a first substrate including a first front surface and a first back surface, a first interlayer insulation layer disposed below the first front surface and including a first interconnect, a second substrate including a second front surface and a second back surface, a second interlayer insulation layer disposed over the second front surface and below the first interlayer insulation layer to be in contact with the first interlayer insulation layer, and including a second interconnect, a first TSV disposed in a through hole formed by penetrating the first substrate and the first interlayer insulation layer and by etching of a portion of the second interlayer insulation layer, and electrically connecting the first interconnect to the second interconnect, and a passivation layer formed to cover the first TSV. An upper end of the first TSV is located at a height lower than the first back surface.