Au alloy bonding wire

Abstract

An Au alloy bonding wire which comprises an Au alloy matrix containing high purity Au and at least one of high purity Pd and Pt in a total amount of 0.05 to 2 mass %, and, incorporated in the matrix as a trace element, Mg in an amount of 10 to 100 mass ppm, Ce in an amount of 5 to 100 mass %, and at least one of Be, Y, Gd, La, Eu and Si in an amount of each element of 5 to 100 mass % and in a total amount of Be to Si of 5 to 100 mass ppm; an Au alloy bonding wire which comprises the above Au alloy matrix and, incorporated in the matrix as a trace element, Mg and Be and at least one of Y, La, Eu and Si; an Au alloy bonding wire which comprises the above Au alloy matrix and, incorporated in the matrix as a trace element, Mg in an amount of 10 to 100 mass ppm, Si in an amount of 5 to 30 mass ppm, Be in an amount of 5 to 30 mass ppm, and at least one of Ca, Ce and Sn in an amount of 5 to 30 mass ppm. The above bonding wire is a fine diameter Au alloy bonding wire which has a desired strength, exhibits good binding characteristics and good stability for a long period of time, and is improved in the circularity of a pressed ball and the sphericity of a molten ball.

Description

technical field [0001] The present invention relates to a gold alloy bonding wire for wire bonding of a semiconductor element, which is used to realize connection between an external lead of a circuit board and an electrode on a semiconductor integrated circuit element, and more particularly relates to a process for making the first bonding and the second bonding A gold alloy bonding wire with improved solderability and a gold alloy bonding wire with improved molten ball sphericity and crimped ball circularity. Background technique [0002] Generally, gold alloy bonding wires containing high-purity gold with a purity of not less than 99.99% by mass are widely used as wires with a diameter of about 25 to 35 μm for realizing connection between external leads and semiconductor chip electrodes used in semiconductor devices . Among the connecting methods of gold alloy bonding wires, the ultrasonic-thermal compression bonding method is generally mainly used for the first bonding....

AI Technical Summary

Problems solved by technology

[0011] In the case of adding trace elements to the gold alloy wire, the higher the concentration of the trace element relative to the gold alloy wire, the higher the absolute rigidity of the gold alloy wire and the better various performances , but on the other hand, there is also bad performance

An example is the deterioration of the formability of gold balls due to elements added to the gold alloy matrix while the ring formability is enhanced

Wedging also deteriorates

In addition, there is also the defect that the hardness of the gold alloy ball increases due to elements added to the gold alloy matrix

[0012] Therefore, there will be problems such as molten balls or crimped balls becoming deformed, making it difficult to perform ball bonding at narrow pitches, or causing increased chip cracking; so the addition of trace elements should not be large

For example, in the case of adding Ca element alone to ensure strength, part of Ca will be deposited on the surface of the thin wire, and then the deposited Ca will be oxidized to form a surface oxide film, which will cause the problem of the spherical shape of the first weld and the weldability has been unstable , so the roundness of the crimped ball becomes worse, and at the same time the wedge bondability of the second weld also worsens

[0013] In addition, in the complex case of adding multiple types of elements to the gold alloy, the way these elements act in the gold alloy will be more complicated, and may be deposited on the surface of the molten ball, so good initial welding cannot be obtained, and at the same time There is also an increasing tendency that reliable first welds and good second weld weldability are no longer possible

[0014] In short, the current situation is that by selecting the type and amount of alloying elements to achieve a balance to achieve the wire properties required for thin wires; due to the higher requirements for the wire properties of thin wires, the combination of elements The exploration is endless

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