Photosensitive Module Packaging With Sidewall RDL Leakage Isolation
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Solution Overview
Problem
Current semiconductor device packaging for optical sensors faces challenges in efficiently making electrical connections through the substrate, leading to potential leakage issues due to the proximity of conductive redistribution layers to the semiconductor material, which affects the reliability and performance of the optical sensor modules.
Innovation Solution
The implementation of a side-T type electrical connection through a chamfered structure on the inclined sidewall of the optical sensor die, where a step-like structure with a flat surface is formed by depositing an insulating dielectric layer using chemical vapor deposition, increasing the separation between conductive RDL traces and the semiconductor material, and using a compliant solder mask to isolate the semiconductor material from the RDL, thereby reducing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conductive redistribution layers are placed close to the semiconductor material for compact packaging, then packaging density is improved, but current leakage increases
Solution Approach 1:
An insulating dielectric layer is introduced as an intermediary between the conductive RDL traces and the semiconductor material. This intermediate layer physically separates the two conductive elements, preventing direct electrical contact and eliminating the leakage path while allowing the RDL to remain in close proximity to the semiconductor material for compact packaging.
Solution Approach 2:
The insulating dielectric layer is selectively deposited only in the regions where RDL traces are in proximity to the semiconductor material. This localized insulation approach provides leakage prevention exactly where needed, while maintaining compact packaging geometry elsewhere without unnecessary material addition.
2Length of moving object
If the substrate thickness is reduced for smaller module size, then miniaturization is improved, but structural strength deteriorates
Solution Approach 1:
The substrate structure is enhanced by integrating multiple materials: the base semiconductor substrate, insulating dielectric layers, conductive RDL traces, and compliant solder mask. This composite structure provides the mechanical strength needed for thin substrates while enabling the miniaturized form factor through the combined properties of different materials.
Solution Approach 2:
A compliant solder mask layer is applied to the substrate surface. This thin film provides mechanical reinforcement and protection to the thinned substrate, allowing the module to achieve a smaller size while maintaining sufficient structural integrity through the flexible yet supportive nature of the solder mask layer.
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 solution effectively reduces current leakage and enhances the reliability of electrical connections in optical sensor modules by increasing the separation between conductive traces and the semiconductor material, improving the overall performance and stability of the packaging.
Implementation Method 1
depositing an insulating dielectric layer by chemical vapor deposition on exposed surfaces of the semiconductor substrate including the inclined sidewalls of the trench and the back side of the semiconductor substrate
Data Source
AI summary
A semiconductor die includes a semiconductor device fabricated in a substrate. The substrate has a front side, a back side, and an inclined sidewall extending from the back side to the front side. A contact pad is connected to the semiconductor device. The contact pad is embedded in an inter dielectric layer (IDL) disposed in the front side. The contact pad has a contact pad edge with a surface aligned along the inclined sidewall. A redistribution layer (RDL) is disposed on the inclined sidewall. The RDL is physically and electrically connected to the contact pad directly through the surface of the contact pad edge aligned along the inclined sidewall.