Dummy UBM Structure Layout for Bonding Strength and Routing Space
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Solution Overview
Problem
The integration density of semiconductor devices is limited by the need for efficient routing and bonding of semiconductor components, leading to device defects and reduced performance.
Innovation Solution
The formation of dummy bumps over redistribution layers (RDLs) with passivation structures and polymer layers, where active bumps are in contact with RDLs and dummy bumps are electrically isolated, improving shear strength and allowing for more routing space and bonding areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the number of bumps is increased to improve bonding area, then bonding strength is improved, but routing space becomes insufficient and device complexity increases
Solution Approach 1:
The patent segments bumps into two functional categories: active bumps that are electrically connected to RDLs for signal transmission, and dummy bumps that are electrically isolated and serve purely for bonding area expansion. This segmentation allows the device to increase total bump count for improved bonding strength without proportionally increasing routing complexity, as dummy bumps require no electrical connections.
Solution Approach 2:
The patent introduces a passivation structure as an intermediary layer between dummy bumps and RDLs. This passivation layer electrically isolates dummy bumps from conductive traces while allowing them to maintain mechanical bonding functionality. The intermediary passivation structure enables increased bonding area without requiring additional routing pathways for dummy bumps.
2Productivity
If more routing pathways are created to accommodate increased component density, then integration density is improved, but device defects increase due to routing congestion
Solution Approach 1:
By segmenting bumps into active and dummy categories with distinct electrical connection requirements, the patent reduces routing congestion. Dummy bumps do not require routing pathways, freeing up space and reducing the complexity of routing networks, thereby lowering the risk of routing-related defects while maintaining high integration density.
Solution Approach 2:
The patent uses dummy bumps as copies or replicas of active bumps in terms of physical structure and bonding functionality, but removes the electrical connection requirement. This copying approach allows the device to increase bonding area and integration density without proportionally increasing routing complexity and associated defect risks.
3Ease of manufacture
If dummy bumps are electrically connected to RDLs like active bumps, then manufacturing process is simplified, but routing space is consumed and bonding area efficiency decreases
Solution Approach 1:
The patent segments the bump population into active and dummy categories with different electrical connection requirements. This segmentation optimizes the balance between manufacturing complexity and space utilization: active bumps receive full manufacturing treatment including electrical connections, while dummy bumps use simplified processes without electrical connections, maximizing routing space efficiency.
Solution Approach 2:
The passivation structure serves as an intermediary that enables dummy bumps to be manufactured with simplified processes (without requiring electrical connection pathways) while still providing adequate bonding functionality. The passivation layer selectively isolates dummy bumps from RDLs, allowing manufacturing simplification without compromising bonding area efficiency.
Data Source
AI summary
Methods for forming dummy under-bump metallurgy structures and semiconductor devices formed by the same are disclosed. In an embodiment, a semiconductor device includes a first redistribution line and a second redistribution line over a semiconductor substrate; a first passivation layer over the first redistribution line and the second redistribution line; a second passivation layer over the first passivation layer; a first under-bump metallurgy (UBM) structure over the first redistribution line, the first UBM structure extending through the first passivation layer and the second passivation layer and being electrically coupled to the first redistribution line; and a second UBM structure over the second redistribution line, the second UBM structure extending through the second passivation layer, the second UBM structure being electrically isolated from the second redistribution line by the first passivation layer.