EFFECT OF ARGON ION-BOMBARDMENT ON DIFFUS ION BONDING JOINTS OF CU ORTI

Ion bombardment is known to be effective in removing all surface conta minants and oxides. Bonding is often carried out after the bonding sur face is cleaned using ion bombardment. However, it is not clear what c hanges occur at the surface. This investigation has been carried out t o determine what changes occur at the surface of a metal and improve t he quality of joint. Joints were made using samples estimated by Auger spectroscopy in an ultra-high vacuum joining equipment. To observe ch anges at the surface, surface composition, surface morphology, hardnes s and fracture surface were investigated. Results obtained are summari zed as follows; 1. Joints could not be made at room temperature but at 300 degrees C using copper samples treated by argon ion bombardment. The joint strength depended on the accelerating voltage at ion bombard ment. It was best to bond the samples treated at accelerating voltage of 2 kV. The joint strength decreased with a rise of accelerating volt age above 2 kV. 2. When ion bombardment was carried out at acceleratin g voltage up to 2 kV, the increase of joint strength depended on the r ise of purity of the bonding surface. 3. Argon ion bombardment at the accelerating voltages from 2 up to 5 kV formed a hard surface layer. T his layer was removed by the annealing treatment of samples after argo n ion bombardment. With softening of the bonding surface, the joint st rength increased. A reason for the decrease of bondability was the for mation of the hard surface layer. 4. Surface roughness increased with accelerating voltage. The decrease in joint strength was not attribute d to the change of surface roughness, as the change of the bonding are a was little. 5. The annealing treatment of the samples after ion bomb ardment was effective to remove the surface damage.