Highly conformal hafnium silicate film growth by atomic-layer chemical vapor deposition using a new combination of precursors: Hf(OC(CH3)(3))(4) and Si(N(CH3)(C2H5))(4)

Abstract

Highly conformal hafnium silicate films were deposited by atomic-layer chemical,vapor deposition (ALCVD) using a new combination of precursors: hafnium tetra-tert-butoxide [Hf(OC(CH3)(3))(4)] and tetrakis-ethylmethylaminosilane [Si(N(CH3)(C2H5))(4)]. The self-limiting nature of ALCVD film growth was demonstrated by showing the convergent growth rate at high concentrations of the precursors. The growth rate was 3.8 angstrom/cycle at 220 degrees C, which was relatively high compared with results using other precursors. It was also shown that we could control the Hf/(Hf + Si) composition ratio in the high Hf/(Hf + Si) ratio region. The carbon impurity concentrations of the films made were lower than the X-ray photoelectron spectroscopy (XPS) detection limit (< 1 at. %). Hafnium silicate films with similar to 80% HfO2 were amorphous up to 700 degrees C. The hafnium silicate films deposited at 220 degrees C have an average dielectric constant of 9.8 with a flatband voltage (V-fb) and a hysteresis voltage in capacitance-voltage (C-V) measurements of 0 V and less than 0.18 V, respectively.