Spectroscopic study of plasma using zirconium tetra-tert-butoxide for the plasma enhanced chemical vapor deposition of zirconium oxide

Plasma enhanced chemical vapor deposition of zirconium oxide using zirconiu m tetra-tert-butoxide (ZTB) as a metalorganic precursor, Ar as a carrier of the ZTB vapor, and O-2 as an oxidant was investigated by using optical emi ssion spectroscopy (OES), Langmuir probe, and x-ray photoelectron spectrosc opy (XPS). The electron temperature (T-e) and the O-2 to Ar flow rate ratio (O-2/Ar) were found to dominate the plasma chemistry: the T-e determined t he maximum Zr and Zr+ emission intensities at an intermediate pressure of 4 5 mTorr, the high C/C-2 emission intensity ratio in the oxygen-rich plasma, and the transition between the dissociation-dominated chemistry at low pre ssures and the recombination-dominated chemistry at high pressures. The O-2 /Ar ratio changed the relative abundance of various atomic and diatomic spe cies in the plasma: both ionic and atomic Zr species were depleted with the addition of O-2 and a significant amount of ZrO and CO was produced. The O -2/Ar ratio and T-e determined the concentration ratio of C/O and C-2/O in the plasma, the production and dissociation rates of diatomic molecules (C- 2, CH, CO, and OH), and the degree of decomposition. From XPS, x-ray diffra ction, and OES measurements, the deposited ZrO2 was found to be stoichiomet ric and amorphous at O-2/Ar ratios greater than or equal to0.2, and hydroca rbon molecules rather than atomic carbon were more responsible for the carb on incorporation into the film. The carbon content in the film could be con trolled by monitoring and varying the OES intensity ratio of C-2 at 516.52 nm to O at 777.42 nm. (C) 2001 American Vacuum Society.