Redistribution Substrate Dummy Pattern for Stable Under Bump Routing
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Solution Overview
Problem
Existing semiconductor packages face reliability issues due to undulations in redistribution patterns and inadequate spacing between under bump patterns, leading to potential electrical connection failures and reduced high power characteristics.
Innovation Solution
Incorporating a dummy pattern between under bump patterns on a redistribution substrate, with specific spacing and material properties, to reduce undulations and enhance electrical connectivity, while maintaining high power characteristics through optimized thickness and angle configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If under bump patterns are closely spaced to improve area utilization, then area efficiency is improved, but undulations occur in redistribution patterns leading to reliability degradation
Solution Approach 1:
A dummy pattern is introduced as an intermediary element between the under bump patterns. This dummy pattern acts as a mediator that absorbs the mechanical stress and prevents undulations in the redistribution pattern, thereby maintaining reliable electrical connections while allowing close spacing of functional under bump patterns for area efficiency.
Solution Approach 2:
The dummy pattern is specifically positioned only in regions where undulations would occur between under bump patterns, while the under bump patterns themselves maintain their functional spacing. This localized addition of the dummy pattern addresses the reliability issue without compromising the area utilization of the functional elements.
2Reliability
If dummy pattern thickness is increased to reduce undulations, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The thickness of the dummy pattern is optimized to a specific range (50-200 nm) that is sufficient to prevent undulations and improve reliability, while remaining thin enough to be formed using standard atomic layer deposition (ALD) processes. This parameter optimization balances reliability improvement with manufacturing simplicity.
3Area of stationary object
If redistribution pattern spacing is reduced to improve density, then area efficiency is improved, but high power characteristics deteriorate
Solution Approach 1:
The dummy pattern serves as a thermal management intermediary by providing a thermally conductive path between under bump patterns. This allows closer spacing of under bump patterns for density improvement while the dummy pattern maintains thermal dissipation pathways to preserve high power characteristics.
Data Source
AI summary
A semiconductor package includes a redistribution substrate, and a semiconductor chip disposed on a top surface of the redistribution substrate. The redistribution substrate includes under bump patterns laterally spaced apart from each other, a dummy pattern disposed between the under bump patterns, a passivation pattern disposed on a bottom surface of the dummy pattern, an insulating layer covering top surfaces and sidewalls of the under bump patterns and a sidewall and a top surface of the dummy pattern, and a redistribution pattern disposed on one of the under bump patterns and electrically connected to the one under bump pattern. The passivation pattern includes a different material from that of the insulating layer.