Sensor Semiconductor Device Circuit Layer Inversion
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Solution Overview
Problem
Conventional CSP sensor semiconductor devices face issues with circuit cracking due to stress concentration at contact points and complex fabrication processes, leading to increased costs and reliability concerns.
Innovation Solution
A fabrication method involving a substrate with electrical contacts, a sensor chip with a transparent cover, a dielectric layer exposing electrode pads, and a circuit layer connected to both, with solder balls for external connection, ensuring the sensor chip is tested before attachment to prevent stress concentration and simplify the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circuit layer is formed on the sidewall of the inclined opening to connect with the electrode pad, then electrical connection is achieved, but stress concentrates at the contact position causing circuit cracking
Solution Approach 1:
Instead of forming the circuit layer on the sidewall of the inclined opening (conventional approach), the patent inverts the approach by forming the circuit layer on the flat bottom surface of the opening. This inversion eliminates the acute angle contact geometry that causes stress concentration, thereby preventing circuit cracking while maintaining electrical connection reliability.
2Device complexity
If wafer-stage fabrication is used to form the CSP sensor semiconductor device, then integration is achieved, but fabrication processes become complicated and fabrication cost increases
Solution Approach 1:
The patent segments the fabrication process into distinct stages: wafer-stage processes for forming the sensor chip structure, followed by singulation to separate individual chips, and then packaging processes. This segmentation allows each stage to be optimized independently, simplifying the overall fabrication process and reducing costs compared to complete wafer-stage integration.
Solution Approach 2:
The patent performs preliminary actions at the wafer stage such as forming the sensor regions and basic chip structure, then completes the device assembly after singulation. This preliminary action approach allows for efficient batch processing of sensor chips while avoiding the complexity of completing all fabrication steps at the wafer stage, thereby reducing overall fabrication cost.
Data Source
AI summary
A sensor semiconductor device and a fabrication method thereof are provided. The fabrication method includes mounting a sensor chip on a surface of a substrate; forming a transparent cover on the sensor chip; forming a dielectric layer and a circuit layer on the substrate, wherein the sensor chip is electrically connected to the substrate through the circuit layer and the transparent cover is exposed from the dielectric layer such that light can pass through the transparent cover to reach a sensor region of the sensor chip and allow the sensor chip to operate; and implanting a plurality of solder balls on another surface of the substrate to electrically connect the sensor chip to an external device. The sensor semiconductor device can be cost-effectively fabricated, and the circuit cracking and known good die (KGD) problems of the prior art can be avoided.