CHARGING DAMAGE DURING PLASMA ENHANCED SILICON NITRIDE/OXIDE THIN FILM DEPOSITION

摘要

Charging damage during plasma enhanced dielectric thin film deposition is a surprisingly severe problem. Given that the dielectric films are highly isolative, it is counter intuitive to have charging damage problem at all. More surprising still is that when the gate oxide becomes ultra thin (< 3nm), other more damaging plasma processes tend to have diminished impact while charging damage from dielectric deposition remains a serious problem. It is shown here that the combination of photoconduction, internal photoemission and high temperature acceleration of breakdown can explain the charging damage during plasma enhanced dielectric deposition. Details of the conduction process, including polarity effect are explained. The recently measured oxide photoconductivity is shown to be in agreement with expectation. The main cause of severe charging damage is the low level of charging stress coupled with high processing temperature.