Energetic particle bombardment of films during magnetron sputtering

Abstract

The flux of energetic, neuiral particles bombarding the sample location during magnetron sputtering has been measured for several cathode—gas systems of general interest. The technique used a differentially pumped detector placed at the sample location, from 5 to 9 cm from the cathode. The detector screens out charged particles, and measures the. secondary electrons produced by energetic neutral bombardment of a collector coated with a thin film of cathode material. The energetic neutral flux has been measured as a function of chamber pressure over a range of 5 to 30 mTorr, as a function of discharge power, and as a function of angle (up to 30) for cathodes of Ti, Cu, Al, Mo, T, and W, in Ar, Ne, and Kr gases. The deposition rate of the film was measured by means of a quartz-crystal oscillator adjacent to the detector. The magnitude of the arriving, energetic neutral flux increased with decreasing gas mass or increasing cathode mass, as expected. The energetic neutralfiux was found to increase with decreasing pressure, but the ratio of energetic neutrals to condensing films atoms was found to decrease slightly with decreasing pressure. The arrival rate of energetic neutrals ranged from 2-4% of the depositing atom flux for Ar4-+Cu to 12%-20% for Ar+->Ti to 27%-5Q% for Ne+->Ta. At high discharge powers, the relative arrival rates were higher, due to gas rarefaction in the near cathode region. © 1989, American Vacuum Society. All rights reserved.