Effects of localized contamination with copper in MOSFETs

Abstract

Using a relatively large size MOSFET (W/L = 15/15 mum), we investigated the degradation of MOSFET characteristics due to localized copper contamination. In order to contaminate a part of the active region of MOSFET, silicon nitride (Si3N4) over the active region, which is known to be a protective film against copper, was etched by reactive ion etching (RIE). As the area of localized copper contamination is about 34 mum or above, apart from the edge of the gate electrode, no degradation was observed after thermal treatment at 450 degreesC for 2 h in N-2 ambient, based on the result of the increase in interface trap density (DeltaD(it)).