Wafer Bonding Double-Ring Retaining Wall Alloy Overflow
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Solution Overview
Problem
Current wafer bonding methods face issues with alloy overflow and misalignment during the bonding process due to the use of single-ring annular retaining wall structures, leading to undesired wafer-bonding results.
Innovation Solution
The implementation of double-ring annular retaining wall structures on both wafers, with moderate-slope sidewalls and controlled thickness, to prevent alloy overflow and improve alignment accuracy by forming a closed overflow trench between the retaining walls and the wafer surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-ring annular retaining wall structures are used, then device complexity is reduced, but alloy overflow occurs and manufacturing precision deteriorates
Solution Approach 1:
The single-ring annular retaining wall structure is segmented into multiple rings (first annular retaining wall and second annular retaining wall) that are separated from each other. This segmentation prevents alloy overflow more effectively while maintaining alignment accuracy during wafer bonding, resolving the contradiction between structural simplicity and manufacturing precision.
2Ease of manufacture
If single-ring annular retaining wall structures are used, then ease of manufacture is improved, but reliability of bonding process deteriorates due to alloy overflow
Solution Approach 1:
The retaining wall is divided into multiple segmented rings that can be manufactured using standard photolithography and etching processes. The segmentation design maintains ease of manufacture while significantly improving bonding process reliability by preventing alloy overflow that would compromise bond quality.
3Productivity
If metal layer width is reduced, then productivity is improved by enabling narrower bonding interfaces, but alloy overflow risk increases without proper containment
Solution Approach 1:
The segmented annular retaining wall structure provides effective containment for the metal layers, allowing narrower bonding interfaces to be used without increasing alloy overflow risk. The multiple rings create containment zones that secure the molten alloy during bonding, enabling higher productivity through reduced metal layer widths.
4Manufacturing precision
If double-ring annular retaining wall structures are implemented, then manufacturing precision is improved by preventing alloy overflow, but device complexity increases
Solution Approach 1:
The double-ring structure is implemented through segmentation of the retaining wall into multiple annular sections. While this increases structural complexity, the segmentation approach uses standard fabrication processes and provides significant benefits in preventing alloy overflow and improving alignment accuracy, making the increased complexity worthwhile.
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 approach enhances the wafer-bonding result by reducing the risk of alloy overflow and improving alignment precision, allowing for a narrower metal layer width while maintaining effective bonding, thus improving the overall quality of the wafer-bonded structure.
Implementation Method 1
bonding the first metal layer and the second metal layer together
Data Source
AI summary
A wafer bonding method includes providing a first wafer including a first wafer surface, forming a first metal layer on the first wafer surface, and forming a first annular retaining wall structure including a first annular retaining wall and a second annular retaining wall surrounded by the first annular retaining wall. The first metal layer is formed between the first annular retaining wall and the second annular retaining wall. The method includes providing a second wafer including a second wafer surface, forming a second metal layer on the second wafer surface, and forming a second annular retaining wall structure including a third annular retaining wall and a fourth annular retaining wall surrounded by the third annular retaining wall. The second metal layer is formed between the third annular retaining wall and the fourth annular retaining wall. The method further includes bonding the first metal layer to the second metal layer.