Effect of sputter heating in ionized metal physical vapor deposition reactors

Ionized metal physical vapor deposition (IMPVD) is a process in which sputt ered metal atoms from a magnetron target are ionized by a secondary plasma, accelerated into the substrate, and deposited with moderately anisotropic fluxes. The momentum and energy transfer from the sputtered metal atoms and ion-produced reflected neutrals to the background gas, sputter heating, pr oduces rarefaction which influences the operating characteristics of the di scharge. To address these processes, a model was developed to simulate the sputtering of metal atoms and their transport in IMPVD reactors. The model accounts for the ion-energy-dependent yield and kinetic energy of the sputt ered and reflected atoms, and for sputter heating. The model was validated by comparing its results to experimentally measured metal atom densities an d the ionization fraction of the deposition flux. Sputter heating as a func tion of auxiliary ionization and magnetron power in an inductively coupled plasma IMPVD reactor for Al deposition was then investigated. Sputter heati ng produces rarefaction of the buffer gas which results in a redistribution of Al species in the reactor compared to the absence of sputter heating. C onsequently, the ionization fraction of the depositing metal flux decreases , while the magnitude of the flux increases. The minimum Ar density due to sputter heating is regulated by heat transfer to the target. The electron d ensity increases significantly with the addition of a small amount of metal atoms to the plasma. (C) 2000 American Institute of Physics. [S0021-8979(0 0)04410-8].