Coupling of radio‐frequency bias power to substrates without direct contact, for application to film deposition with substrate transport

Abstract

We have demonstrated the coupling of 13.56 MHz rf bias power to an electrically floating substrate platform during aluminum sputter deposition by using an rf‐driven electrode spaced 3 mm away from the back of the platform. This electrode gap and the sputtering plasma sheath in series with it form a capacitive voltage divider, so that the peak rf voltage on the platform is 350 V when that on the electrode is 750 V. This amount of coupling produced enough ion bombardment on the aluminum to result in 23% resputtering and an improvement in film sidewall coverage from 10% to 100%. This noncontact, ‘‘proximity’’ method of substrate biasing should greatly facilitate the coupling of rf power into moving substrates in transport‐type deposition processes.