CMOS Sensor Bonding Pad Structure to Prevent Peeling
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Solution Overview
Problem
Existing CMOS image sensors face challenges in achieving efficient integration and miniaturization while maintaining structural integrity and electrical connectivity, particularly in the formation of bonding pads and interconnects, which can lead to peeling and other reliability issues.
Innovation Solution
The formation of a dummy pattern in the trench surrounding the bonding pad and insulator, along with a multi-layer interconnect structure, ensures secure electrical connection and prevents peeling by embedding the dummy pattern between the bonding pad and the semiconductor substrate, using materials like copper and dielectric layers with low k values for reduced capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bonding pads and interconnects are formed in existing CMOS image sensors, then electrical connectivity is achieved, but peeling and reliability issues occur
Solution Approach 1:
A dummy pattern is formed in advance within the trench surrounding the bonding pad before the bonding pad is fully processed. This preliminary structure provides mechanical support and prevents peeling from the outset, addressing the reliability issue before it manifests during operation or testing.
Solution Approach 2:
The dummy pattern acts as an intermediary element between the bonding pad and the underlying semiconductor substrate. It provides a transition zone that distributes mechanical stress and prevents direct peeling at the bonding pad interface, thereby improving reliability without compromising structural integrity.
2Productivity
If miniaturization is pursued in CMOS image sensors, then resolution and integration are improved, but structural integrity and electrical connectivity become difficult to maintain
Solution Approach 1:
The dummy pattern is nested within the trench structure that surrounds the bonding pad. This nested configuration allows the dummy pattern to provide support without occupying additional external space, enabling miniaturization while maintaining the structural integrity needed for reliable electrical connectivity.
Solution Approach 2:
Instead of expanding the bonding pad area horizontally (which would hinder miniaturization), the solution extends the support structure vertically into the trench dimension. This dimensional transition allows the dummy pattern to provide mechanical reinforcement without increasing the planar footprint, thus maintaining integration efficiency.
3Reliability
If dummy pattern is embedded in trench surrounding bonding pad, then peeling is prevented and reliability is improved, but device complexity increases
Solution Approach 1:
The dummy pattern is formed using the same material and processing steps as the existing trench structures in the CMOS image sensor. This homogeneity ensures that the added reliability feature blends seamlessly with the existing device architecture, minimizing the increase in device complexity while maintaining structural integrity.
Data Source
AI summary
A semiconductor device includes a dielectric layer, a semiconductor substrate, a conductive pad and a conductive pattern. The semiconductor substrate is on a first surface of the dielectric layer. The conductive pad is partially embedded in the dielectric layer and partially protruded from the first surface of the dielectric layer to extend over the first surface of the dielectric layer. The conductive pattern is disposed on the dielectric layer and between the semiconductor substrate and the conductive pad.