Etching characteristics of high-kk dielectric HfO(2) thin films in inductively coupled fluorocarbon plasmas

摘要

Inductively coupled fluorocarbon (CF[4]∕Ar and C[4]F[8]∕Ar) plasmas were used to etchHfO[2], which is a promising high-dielectric-constant material for the gate of complementary metal-oxide-semiconductor devices. The etch rates of HfO[2] in CF[4]∕Ar plasmas exceeded those in C[4]F[8]∕Ar plasmas. The tendency for etch rates to become higher in fluorine-rich (high F∕CF∕C ratio) conditions indicates that HfO[2] can be chemically etched by fluorine-containing species. In C[4]F[8]∕Ar plasmas with a high Ar dilution ratio, the etch rate of HfO[2] increased with increasing bias power. The etch rate of Si, however, decreasd with bias power, suggesting that the deposition of carbon-containing species increased with increasing the power and inhibited the etching of Si. The HfO[2]∕Si selectivity monotonically increased with increasing power, then became more than 5 at the highest tested bias power. The carbon-containing species to inhibit etching of Si play an important role in enhancing the HfO[2]∕Si selectivity in C[4]F[8]∕Ar plasmas.