Semiconductor Pillar Bonding Stress Distribution
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Solution Overview
Problem
The semiconductor flip-chip bonding process is fragile due to stress generated at the peripheral bottom portion of metal pillars, leading to potential breakage and reduced reliability, especially when pillars are formed on a passivation layer.
Innovation Solution
The use of two symmetric pillar structures on a single bonding pad, with an insulation layer exposing portions of the bonding pad and pillar structures, reduces stress and improves reliability by distributing the load and absorbing peripheral stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single metal pillar is used on a bonding pad, then the device structure is simple, but stress concentration occurs at the peripheral bottom portion leading to pillar breakage and reduced reliability
Solution Approach 1:
The patent divides a single pillar structure into multiple pillars (first and second pillars) disposed on the bonding pad. This segmentation distributes the stress that would otherwise concentrate at the peripheral bottom portion of a single pillar, reducing the risk of breakage and improving bonding structure reliability.
2Strength
If metal pillars are formed on a passivation layer, then the bonding pad is protected, but stress is generated at the peripheral bottom portion of pillars leading to potential breakage
Solution Approach 1:
The patent applies different properties to different parts of the bonding structure. The passivation layer provides protection where needed, while the multiple pillars are strategically disposed to distribute stress. The insulation layer is selectively positioned to expose portions of the bonding pad, creating local variations in mechanical properties that reduce stress concentration at critical locations.
3Reliability
If two symmetric pillar structures are used on a bonding pad, then stress is distributed and reliability is improved, but the device structure becomes more complex
Solution Approach 1:
While the patent uses symmetric pillar structures for balance, it introduces asymmetric elements through the insulation layer configuration that exposes specific portions of the bonding pad. This controlled asymmetry allows stress distribution while maintaining manufacturability and reducing overall structural complexity compared to fully asymmetric designs.
Data Source
AI summary
The present disclosure relates to bonding structures useful in semiconductor packages. In an embodiment, a semiconductor device includes a semiconductor element, two pillar structures, and an insulation layer. The semiconductor element has a surface and includes at least one bonding pad disposed adjacent to the surface. The two pillar structures are disposed on a single bonding pad. The insulation layer is disposed adjacent to the surface of the semiconductor element. The insulation layer defines an opening, the opening exposes a portion of the single bonding pad, and the two pillar structures are disposed in the opening.