Highly Conformal Hafnium Silicate Film Growth by Atomic-Layer Chemical Vapor Deposition using a New Combination of Precursors: Hf(OC(CH_3)_3)_4 and Si(N(CH_3)(C_2H_5))_4

摘要

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(CH_3)_3)_4] and tetrakis-ethylmethylaminosilane [Si(N(CH_3)-(C_2H_5))_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 A/cycle at 220℃, 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 ～80% HfO_2 were amorphous up to 700℃. The hafnium silicate films deposited at 220℃ 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.