Gold Wire Composition for Semiconductor Bonding
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Solution Overview
Problem
The challenge is to develop a gold wire for semiconductor element connections that balances mechanical strength and bondability while maintaining roundness of press-bonded balls, especially with the downsizing of semiconductor devices and narrower electrode pad pitches, where existing additive elements can lead to oxidation and deteriorated bondability.
Innovation Solution
A gold wire composition including specific amounts of Ca and rare earth elements, along with refractory metals like Ti, V, Cr, Hf, Nb, W, and Zr, and additional elements such as Pr, Pd, and Be, which enhance strength, Young's modulus, and roundness of press-bonded balls, while minimizing oxidation and improving bondability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additive elements are added to improve strength and Young's modulus, then mechanical characteristics are improved, but surface oxidation occurs and bondability deteriorates
Solution Approach 1:
The patent changes the compositional parameters by specifying precise ranges for additive elements (Ca: 0.003-0.01 mass%, rare earth elements: 0.001-0.005 mass%, Ti: 0.001-0.01 mass%) to optimize the balance between mechanical strength and oxidation resistance, ensuring good bondability while maintaining improved strength characteristics
Solution Approach 2:
The patent creates a composite material system combining gold with multiple additive elements (Ca, rare earth elements, Ti, and optionally Pd and Be) that work synergistically to improve mechanical properties while the specific composition ratios prevent excessive oxidation, resolving the contradiction between strength enhancement and bondability maintenance
2Length of moving object
If wire diameter is reduced to meet downsizing requirements, then smaller mounting size is achieved, but mechanical strength becomes insufficient and wire breakage increases
Solution Approach 1:
The patent changes the compositional parameters by adding specific amounts of strength-enhancing elements (Ca: 0.003-0.01 mass%, rare earth elements: 0.001-0.005 mass%) to compensate for the reduced cross-sectional area of thinner wires, allowing 15 μm diameter wires to maintain sufficient mechanical strength and prevent breakage during handling and bonding processes
3Stability of the object's composition
If additive elements are added to improve Young's modulus, then wire stability is improved, but oxidation resistance decreases and bondability is affected
Solution Approach 1:
The patent optimizes the concentration parameters of additive elements (rare earth elements: 0.001-0.005 mass%, Ti: 0.001-0.01 mass%) to achieve the desired Young's modulus improvement while maintaining oxidation resistance, preventing harmful oxidation effects that would compromise bondability
Solution Approach 2:
The patent introduces Ti (titanium) as an intermediary element that works synergistically with Ca and rare earth elements to improve Young's modulus while the controlled composition ratios prevent excessive oxidation, mediating between the need for high stiffness and oxidation resistance
Data Source
AI summary
A gold wire for semiconductor element connection having high strength and bondability. The connection has a limited amount of at least one element selected from calcium and rare earth elements, and a limited amount of at least one element selected from a group consisting of titanium, vanadium, chromium, hafnium, niobium, tungsten, and zirconium. The incorporation of a suitable amount of palladium or beryllium is preferred. The incorporation of calcium and rare earth element can improve the strength and young's modulus of a gold wire, and the incorporation of titanium and the like can reduce a deterioration in the roundness of press-bonded shape of press-bonded balls in the first bonding caused by the incorporation of calcium and rare earth elements. The bonding wire can simultaneously realize mechanical properties and bondability capable of meeting a demand for a size reduction in semiconductor and a reduction in electrode pad pitch.