Micro-interface formation control of electronic devises based on analysis of solid state bonding mechanism

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The adhesion behavior was observed under an ultra-high vacuum condition in order to comprehend the fundamental bonding principle. Al, Au, Cu and Ni fine wires were used as circuit wires and also Au, Al, Cu and Ni foils were used as a electronic pad. The vacuum degree was 1x10^<-8> Pa. Their surfaces were made clean by Ar ion bomberdment before bonding. It was found that the surfaces before Ar ion cleaing has an oxide film but the oide film is removed by Ar ion cleaning based on Auger analysis. In Au-Au bonding, the bonded area formation is produced from center of contacted area as like as Au-Ni and Au-Cu bonding. However, if Al wire is used, the periphery area was firstly bonded and the center area is not easily bonded. In order to make this phenominon to be clear, the adhesion formation behavior was investigated and Auger analysis was carried out after bonding. As a result, it was suggested that the surface of Al was attacted by oxygen and a very thin layer oxide film was formed several ten miniutes after Ar ion cleaning even under the ultra-high vacuum condition and the film had a large influence on the adhesion formation. This is an very important knowledge to control the solid state adhesion process. That is, the folding phenomenon of side surface of Al wire contacted to the pad is necessary for increasing the strong bonded area during the the bonding of Al wire to the pad. Taking this idea into consideration, the interface formation process of Al-Au ar Al-Al, Al-Si bondings was controlled well and also the good formation condition was obtained by measuring the vabration of the bonding tool using leaser Dopplar vibriometer. The results were reported in Symposium of Mate2005 and the final report was made.