Trapezoid Bonding Pads for Reliable Wafer-Level 3D IC Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current 3D ICs experience abnormal signal transmission due to defective bonding between bonding pads, which affects the quality of the bonding interface and overall performance.
Innovation Solution
The use of trapezoid-shaped bonding pads in semiconductor structures for wafer level bonding, where the bottom angle between the sidewall and the bottom surface of the bonding pad is smaller than 90 degrees, ensures intimate contact and reduces stress at the bonding interface, thereby improving bonding quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding pads with right-angle sidewalls are used, then the manufacturing process is simple, but the bonding quality is poor due to defective bonding between bonding pads
Solution Approach 1:
The bonding pad sidewall is designed with an asymmetric angle where the bottom angle (between sidewall and bottom surface) is smaller than the top angle (between sidewall and top surface). This asymmetric geometry creates a tapered profile that improves bonding contact area and eliminates voids, directly resolving the bonding quality issue while maintaining manufacturing feasibility through standard etching processes.
Solution Approach 2:
The invention changes the geometric parameters of the bonding pad by specifying that the bottom angle must be smaller than 90 degrees, creating a tapered profile. This parameter modification transforms the bonding interface geometry to achieve better contact and reduce stress concentration, thereby improving bonding reliability without requiring complex manufacturing steps.
2Reliability
If conventional bonding pads with vertical sidewalls are used, then the fabrication process is straightforward, but stress accumulates at the bonding interface causing defective bonding
Solution Approach 1:
The asymmetric angle configuration (bottom angle < top angle) creates a tapered sidewall profile that distributes stress more evenly across the bonding interface. This geometric asymmetry prevents stress concentration at sharp corners while remaining compatible with conventional etching and fabrication processes.
Solution Approach 2:
By modifying the sidewall angle parameters to create a tapered profile, the invention reduces stress concentration at the bonding interface. The specific requirement that the bottom angle be smaller than 90 degrees creates a gradual transition that eliminates stress singularities, improving bonding reliability through simple geometric parameter adjustment.
3Reliability
If bonding pads with larger contact area are used, then bonding quality improves, but the stress concentration at the bonding interface increases
Solution Approach 1:
The asymmetric tapered profile allows the bonding pad to have a larger top surface area for improved contact while maintaining a smaller bottom cross-section. This geometric configuration increases the bonding contact area for better quality while the tapered shape naturally distributes stress, preventing concentration at any single point at the bonding interface.
Solution Approach 2:
The invention changes the geometric parameters by creating a tapered profile where the bottom angle is smaller than the top angle. This parameter modification enables the bonding pad to achieve both larger contact area and reduced stress concentration simultaneously, as the gradual taper distributes mechanical stress evenly across the bonding interface.
Data Source
AI summary
A semiconductor structure for wafer level bonding includes a bonding dielectric layer disposed on a substrate and a bonding pad disposed in the bonding dielectric layer. The bonding pad includes a top surface exposed from the bonding dielectric layer, a bottom surface opposite to the top surface, and a sidewall between the top surface and the bottom surface. A bottom angle between the bottom surface and sidewall of the bonding pad is smaller than 90 degrees.