Method and experimental arrangement for Al thin film deposition from r.f. metal plasma with simultaneous self-ion bombardment

Abstract

A method, experimental arrangement, and some particular details of the process for Al thin film deposition from r.f. metal plasma are described in this paper. In the plasma deposition system, Al is evaporated by an electron beam, partial ionization of the vapor is realized in r.f. inductive metal plasma, and film deposition is accompanied by simultaneous self-ion bombardment (SSIB) in a high-vacuum environment. Special attention is given to the accurate determination of such basic physical parameters of the process as plasma potential, ion energy, fraction of ions in the total arrival flux, added (normalized) energy, and power density of the ion bombardment. It is concluded that the fraction of secondary neutral energetic atoms in the total flux can be neglected in the calculations of the basic deposition parameters. At the power density in excess of about 0.5 W/cm 2, the substrate temperature can rise up to the Al melting point (660°C) during deposition. An analysis of the main heat sources in the plasma deposition system is presented in the paper. It is found that the results of the computer simulation of the substrate temperature increase caused by ion bombardment have a very good agreement with demonstrated experimental data.