A Study of compressively strained Si0.5Ge0.5 metal-oxide-semiconductor capacitors with chemical vapor deposition HfAlO as gate dielectric

Abstract

The interfacial and electrical properties of metal organic chemical vapor deposited HfAlO on compressively strained Si0.5 Ge0.5 (ε- Si0.5 Ge0.5) substrate without or with surface nitridation treatment were investigated. X-ray photoelectron spectroscopic analysis suggests that an interfacial layer containing Ge Ox, Hf silicate, and Al silicate exists on substrates with direct deposition of HfAlO, whereas an interfacial layer containing Si Nx Oy exists on substrates with surface nitridation prior to HfAlO deposition. The TaNHfAlOε- Si0.5 Ge0.5 capacitor with surface nitridation shows a larger permittivity of the entire gate dielectric with a thinner interfacial layer (in terms of equivalent oxide thickness), a smaller interface trap charge density, and less severe flatband shift as well as two orders of magnitude lower gate leakage in comparison with those capacitors without nitridation. © 2007 American Institute of Physics.