Ag-au-pd ternary alloy-based bonding wire

Abstract

The purpose of the invention is to improve the reliability at which a bonding wire for semiconductors that is used in high-temperature and high-humidity environments is bonded to an aluminum pad. The solution is that a ternary-alloy-based wire comprising 4-10 mass% of gold having a purity equal to or greater than 99.999 mass%, and 2-5 mass% of palladium having a purity equal to or greater than 99.99 mass%, the remainder being constituted by silver having a purity equal to or greater than 99.999 mass%. The bonding wire for semiconductors contains 15-70 wt ppm of an oxidizing non-noble metal j element, and is subjected to an annealing heat treatment before being continuously drawn using a die, to a refining heat treatment after being continuously drawn using a die, and to ball-bonding in a nitrogen atmosphere. Corrosion between an Ag2Al intermetallic compound layer and the Ag-Au-Pd ternary alloy wire at the bonding interface between an aluminum pad and the wire is inhibited by Au2Al and a Pd-rich layer.

Description

Technical field [0001] The present invention relates to a bonding wire made of Ag-Au-Pd ternary alloy. The bonding wire is suitable for connecting a substrate used in a semiconductor device, such as an IC chip electrode, with an external lead wire, and particularly relates to a Ag-Au-Pd ternary alloy bonding wire used under high temperature conditions such as in motor vehicles or in high-speed devices. Background technique [0002] Traditionally, as a gold wire for connecting IC chip electrodes to external lead wires in semiconductor devices, high-purity gold doped with trace amounts of another metal element has been widely used for reasons of high reliability. Gold wire with a purity of more than mass%. The use of this pure gold wire is such that one end of the wire is connected to the pure aluminum (Al) solder joint or aluminum alloy solder joint on the electrode of the IC chip by using ultrasonic assisted hot bonding, and the other end is connected to the external lead on the...

AI Technical Summary

Problems solved by technology

[0007] However, in the case of a bonding wire made of a Ag-Au-Pd ternary alloy, there is a fact that the greater the content of silver (Ag), the more oxygen is introduced from the air, so that the surface tension becomes quite Weak, so that the shape of the molten ball becomes unstable, and also brings about the precipitation of the above-mentioned oxides, it is only possible to obtain the connection by ultrasonic wedge bonding

[0008] Since resin-sealed semiconductor devices have come to be used for automotive device ICs in which high reliability is required despite severe conditions of elevated temperatures, and for ICs for high-frequency waves and high-brightness LEDs whose operating temperatures have been raised to be very high, there have been Bonding wires made of Ag-Au-Pd ternary alloys with final annealing are not able to maintain their properties at such high temperatures

For these reasons, the fact is that the Ag-Au-Pd ternary alloy bonding wire has not been put into use

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