Deep level transient spectroscopy of metal-oxide-semiconductor capacitors fabricated on CF4 reactive-ion-etched Si

Abstract

Metal-oxide-semiconductor capacitors have been fabricated on CF4 reactive-ion-etched silicon in order to study defects at the Si-SiO2 interface and in the bulk of the Si substrate, produced by the combination of reactive ion etching (RIE) and oxidation. High interface state densities (in the range 1010 –1011 cm−2 eV−1 ) are observed for capacitors fabricated with either dry or wet oxidations, and are probably due to disrupted or strained bonds at the Si-SiO2 interface. It is proposed that the disrupted or strained bonds result from implanted impurities and/or lattice defects from RIE that accumulate at the interface during the oxidation process. Capacitors fabricated with a wet oxidation on CF4 -etched Si contain bulk traps in the Si, which may be partly responsible for the low generation lifetimes observed for these samples. The bulk traps are probably related to carbon contamination, in SiC form, introduced during RIE.