Semiconductor Substrate Bonding Pad Density Gradient
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Solution Overview
Problem
The bonding strength between substrates in semiconductor manufacturing is insufficient, leading to potential separation of bonding pads during the die cutting process, which can result in manufacturing failures and reduced yield.
Innovation Solution
A package structure with a bonding pad pattern that includes a higher density of outer bonding pads surrounding a lower density inner bonding pad pattern, enhancing the mechanical and bonding strength between substrates, particularly through the use of a dummy outer bonding pad pattern to withstand cutting forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional bonding pad pattern is used, then the manufacturing process is simple, but the bonding strength between substrates is insufficient
Solution Approach 1:
The bonding pad pattern is segmented into two distinct regions: an inner bonding pad pattern for electrical connection and an outer bonding pad pattern for mechanical strength. This segmentation allows each region to serve its specific function optimally without compromising the other.
Solution Approach 2:
Different regions of the bonding pad pattern are assigned different densities and functions. The inner region has lower density for electrical connectivity, while the outer region has higher density for mechanical bonding strength. This local differentiation resolves the contradiction by optimizing each area for its specific purpose.
2Reliability
If the bonding strength is increased through higher bonding pad density, then the bonding between substrates is improved, but the manufacturing complexity increases
Solution Approach 1:
The bonding pad structure is divided into functional segments with different densities. The outer bonding pad pattern with higher density provides reliable bonding, while the inner pattern maintains necessary electrical connections. This segmentation achieves reliability without requiring uniform high-density bonding pads throughout.
Solution Approach 2:
Higher bonding pad density is applied only where mechanically needed (outer region), rather than uniformly across the entire bonding interface. This partial application of excessive density achieves the necessary bonding reliability while minimizing overall structural complexity.
3Strength
If the outer bonding pad pattern with higher density is used, then the mechanical strength during cutting is improved, but the area available for electrical bonding is reduced
Solution Approach 1:
The bonding pad area is segmented into two functional zones: the outer zone with higher density for mechanical strength during cutting, and the inner zone with lower density for electrical bonding. This spatial segmentation resolves the area conflict by dedicating specific regions to specific functions.
Solution Approach 2:
Different areas of the bonding pad pattern have different densities tailored to local requirements. The outer perimeter area has higher density for mechanical reinforcement during die cutting, while the central area maintains lower density to preserve electrical bonding functionality. This local optimization resolves the area trade-off.
Data Source
AI summary
A package structure of a semiconductor device includes a first substrate, a second substrate, and a bonding layer. The bonding layer bonds the first substrate and the second substrate. The bonding layer includes an inner bonding pad pattern and an outer bonding pad pattern formed in a dielectric layer. The outer bonding pad pattern surrounds the inner bonding pad pattern. A first bonding pad density of the outer bonding pad pattern is greater than a second bonding pad density of the inner bonding pad pattern.