Atomic layer chemical vapor deposition and electrical characterization of hafnium silicate films

Abstract

Atomic layer chemical vapor deposition (ALCVD) of hafnium silicate films using a precursor combination of tetrakis (diethylamido) hafnium, Hf(N(C2H5)(2))(4), and tetra-n-butyl orthosilicate, Si((OBu)-Bu-n)(4) was studied for high-dielectric gate oxides. The ALCVD temperature window in our study was 290-350 degrees C with a growth rate of 1.1 angstrom/cycle. We investigated the effect of deposition conditions, such as deposition temperature, pulse time of precursor, and purge injection, on the film growth. The saturated composition of the Hf/(Hf + Si) ratio was 0.37, and the impurity concentrations were less than 1 atom %. The dielectric constant (k) of the as-deposited hafnium silicate film increased upon annealing at 600 degrees C, but decreased for annealing above 800 degrees C. Hysteresis in the capacitance-voltage measurements was less than 0.3 V before and after annealing. The leakage current density of the as-deposited, 600 degrees C, and 800 degrees C annealed films was 5.3 x 10(-2), 2.2 x 10(-2), and 2.7 x 10(-6) A/cm(2), respectively, at a bias of -1 V. (c) 2005 The Electrochemical Society.