Substrate Bombardment During RF Sputtering

Abstract

It is shown, that for the conditions relevant to the “peak” type of rf sputtering arrangement, and in fact most rf sputtering devices, that ions are essentially unaware of the existence of the rf fields and respond only to the dc fields generated. This enables the sputtering parameters to be viewed in a simple, physical way and calculations based on this approach are shown to be fairly exact. A deduction from the theory is that the majority of the secondary electrons released by ion bombardment of the target plates strike the substrate table with considerable energy. A special gridded probe in the substrate table enabled the simple theory to be verified quantitatively and also verified the existence of the high-energy electrons. By controlling substrate bombardment during sputtering with another grid arrangement, the effects of this high-energy electron bombardment on film adherence and appearance was demonstrated.