Semiconductor Electrode Dummy Metal Crack Suppression
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Solution Overview
Problem
Conventional electrode structures for semiconductor chips suffer from electrical shorts between adjacent solder bumps and crack generation due to bump stress concentrated on under-edge portions below the barrier metal, which compromises the reliability of the bump connection.
Innovation Solution
The electrode structure incorporates a dummy pattern of metals between the pad-form wiring metal and the wiring metal, positioned in a range including the under-edge of the barrier metal, with a resin protective film that does not cover this area, to prevent electrical shorts and alleviate stress-induced cracks. This pattern can include multiple metals spaced evenly, forming a continuous surface, such as a dot or honeycomb pattern, with no potential or the same potential as the pad-form wiring metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resin protective film covers the entire upper surface including under-edge portions below the barrier metal, then the protective coverage is improved, but bump stress concentrates on the under-edge portions causing crack generation
Solution Approach 1:
The resin protective film is selectively formed to cover only specific regions (pad-form wiring metal and wiring metal) while intentionally leaving the under-edge portions below the barrier metal uncovered. This local differentiation allows the protected areas to maintain reliability while the uncovered under-edge portions can relieve stress concentration, preventing crack generation.
2Ease of manufacture
If the opening at the pad connecting metal is positioned to allow resin protective film coverage, then manufacturing simplicity is improved, but electrical shorts occur between adjacent solder bumps during plating
Solution Approach 1:
The barrier metal serves as an intermediary structure that physically separates the pad connecting metal from adjacent structures. By positioning the opening where the pad connecting metal contacts the barrier metal, the design uses the barrier metal as a mediator to prevent conductive components from bridging adjacent solder bumps during plating, thus preventing electrical shorts while maintaining manufacturing simplicity.
3Productivity
If the pad pitch is reduced to increase device density, then productivity is improved, but the risk of electrical shorts and crack generation increases
Solution Approach 1:
The electrode structure is segmented into distinct functional regions: pad-form wiring metal, barrier metal, wiring metal, and dummy metal patterns. This segmentation creates physical and electrical isolation between adjacent structures, allowing reduced pad pitch while maintaining reliability by preventing interactions that cause electrical shorts and stress concentration between neighboring electrodes.
Solution Approach 2:
The barrier metal and dummy metal patterns act as intermediary structures between adjacent electrodes. These intermediaries provide physical separation and stress distribution, enabling closer spacing of electrodes (reduced pad pitch) while preventing electrical shorts and crack generation that would otherwise occur at higher densities.
Data Source
AI summary
The bump electrode 100 of the present invention has a structure in which dummy metals 111 are provided in the uppermost layer portion of a silicon 101 between a pad-form wiring metal 102 and a wiring metal 103 such that an edge of each dummy metal and an edge of the barrier metal 107 are not aligned in a line, and a lot of interfaces are formed between the dummy metals 111 and an interlayer film 140, and therefore expansion of a crack generated due to bump stress concentrated on the under-edge portion 109 below the barrier metal 107 between the pad-form wiring metal 102 and the wiring metal 103 is suppressed.