TSV Image Sensor Passivation Structure for Void-Free Gap Fill
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Solution Overview
Problem
Existing image sensing devices with through silicon via (TSV) structures face reliability issues due to defects in the gap-fill structure, particularly during Temperature Humidity with Bias (THB) testing, where voids in the passivation layer can lead to failure in electrical connections.
Innovation Solution
The implementation of an improved image sensing device design that includes a through silicon via (TSV) structure with a passivation layer composed of a first photoreactive material layer and a second photoreactive material layer with different photoreaction characteristics, which fills the through hole and enhances gap-fill characteristics to prevent defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer passivation layer is used to fill the through hole, then the manufacturing process is simple, but voids form during THB testing leading to connection failures
Solution Approach 1:
The passivation layer is divided into two distinct layers: a first photoreactive material layer and a second photoreactive material layer with different photoreaction characteristics. This segmentation allows each layer to perform different functions - the first layer provides gap-fill characteristics to prevent voids, while the second layer provides planarization and protection, thereby improving reliability without excessive complexity
Solution Approach 2:
The patent uses composite photoreactive material layers with different photoreaction characteristics. The first layer has gap-fill characteristics that prevent void formation, while the second layer has different photoreaction properties for planarization. This composite structure combines the advantages of different materials to achieve both void prevention and surface planarity, resolving the contradiction between reliability and manufacturing simplicity
2Reliability
If the through hole is not properly filled, then manufacturing is easier, but voids lead to connection failures during THB testing
Solution Approach 1:
The first photoreactive material layer is specifically designed with gap-fill characteristics localized to the through hole region. This layer has different properties than the second layer, with the first layer optimized for filling voids and the second layer optimized for planarization and protection. This local quality approach ensures proper gap-fill where needed while maintaining ease of manufacture through standardized photoreactive material processing
Solution Approach 2:
The patent changes the photoreaction characteristics parameter between the two layers. The first layer has photoreaction characteristics optimized for gap-fill (preventing voids), while the second layer has different photoreaction characteristics optimized for planarization. By controlling photoreaction parameters differently in each layer, the patent achieves reliable void-free filling while maintaining compatibility with standard manufacturing processes
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
This design improves the reliability of the TSV structure by preventing defects during THB testing, ensuring stable electrical connections and enhanced performance in high-humidity environments.
Implementation Method 1
a passivation layer disposed over the TSV structure to fill the through hole, the passivation layer including a first photoreactive material layer formed to fill a lower region of the through hole, and a second photoreactive material layer disposed over the first photoreactive material layer in the through hole
Data Source
AI summary
An image sensing device includes a semiconductor substrate, an insulation layer disposed below the semiconductor substrate, a through hole formed to extend to the inside of the insulation layer while penetrating the semiconductor substrate, a through silicon via (TSV) structure formed along an inner surface of the through hole, and a photoresist formed over the TSV to gap-fill at least a portion of the through hole.