Wafer Bonding Alignment Mark Point Array Top Cover
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Solution Overview
Problem
Current wafer bonding technologies face challenges in accurate alignment due to the instability of lithographic alignment patterns being covered by other material layers, leading to deviations in bonding hole alignment.
Innovation Solution
A semiconductor wafer design featuring a bonding alignment mark formed by a point array in the top cover layer, which is not covered by other material layers, facilitating recognition and integration with the bonding hole process, and avoiding defects like dishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If lithographic alignment pattern is used for bonding alignment, then bonding alignment can be achieved, but the alignment recognition becomes unstable when the top metal layer is covered by other material layers
Solution Approach 1:
The bonding alignment mark is extracted from the covered top metal layer and placed in the top cover layer which is not covered by other material layers. This separates the alignment function from the interconnection structure, allowing stable optical recognition while maintaining the electrical connection function of the covered metal layer.
Solution Approach 2:
The top cover layer serves as an intermediary layer that provides a stable, accessible surface for the bonding alignment mark. This intermediary layer allows the bonding device to recognize alignment patterns without being blocked by the overlying material layers, while the actual bonding connections are still made through the covered interconnection structure.
2Manufacturing precision
If indirect alignment method is used through lithographic alignment pattern, then bonding alignment can be achieved, but the alignment accuracy is insufficient for precise bonding hole alignment
Solution Approach 1:
The indirect lithographic alignment method is replaced with a direct optical alignment method. The bonding alignment mark in the top cover layer provides direct optical contrast for the bonding device, replacing the indirect alignment through covered metal layers with a direct visual recognition system that achieves higher precision.
Solution Approach 2:
The bonding alignment mark utilizes optical contrast (analogous to color changes) in the top cover layer to provide clear visual recognition for the bonding device. The mark's optical properties differ from the surrounding top cover layer, enabling precise detection and alignment without relying on indirect lithographic patterns.
Data Source
AI summary
A semiconductor wafer, a bonding structure, and a wafer bonding method are provided. In the semiconductor wafer, a bonding pad which is electrically connected to the interconnection structure is formed in the top cover layer, and a bonding alignment mark formed by a point array is disposed in the top cover layer. In this way, the bonding alignment mark is disposed in the top cover layer, and the top cover layer is not covered by another material layer, thereby facilitating recognition of the alignment pattern by the bonding device and increasing the alignment window in bonding process. Moreover, the bonding alignment mark is formed by a point array, thereby facilitating integration of the process for forming the bonding alignment mark with the bonding hole process and avoiding defects such as the dishing phenomenon in the manufacturing process.