Plasma enhanced chemical vapor deposition of zirconium oxide using zirconium tetra-tert-butoxide (ZTB) as a metalorganic precursor, Ar as a carrier of the ZTB vapor, and O2 as an oxidant was investigated by using optical emission spectroscopy (OES), Langmuir probe, and x-ray photoelectron spectroscopy (XPS). The electron temperature (Te) and the O2 to Ar flow rate ratio (O2/Ar) were found to dominate the plasma chemistry: the Te determined the maximum Zr and Zr+ emission intensities at an intermediate pressure of 45 mTorr, the high C/C2 emission intensity ratio in the oxygen-rich plasma, and the transition between the dissociation-dominated chemistry at low pressures and the recombination-dominated chemistry at high pressures. The O2/Ar ratio changed the relative abundance of various atomic and diatomic species in the plasma: both ionic and atomic Zr species were depleted with the addition of O2 and a significant amount of ZrO and CO was produced. The O2/Ar ratio and Te determined the concentration ratio of C/O and C2/O in the plasma, the production and dissociation rates of diatomic molecules (C2, CH, CO, and OH), and the degree of decomposition. From XPS, x-ray diffraction, and OES measurements, the deposited ZrO2 was found to be stoichiometric and amorphous at O2/Ar ratios ⩾0.2, and hydrocarbon molecules rather than atomic carbon were more responsible for the carbon incorporation into the film. The carbon content in the film could be controlled by monitoring and varying the OES intensity ratio of C2 at 516.52 nm to O at 777.42 nm.

The origin of impurity incorporation in the ZrO2 films deposition by plasma-enhanced chemical vapor deposition with Ar-carried zirconium t-butoxide (ZTB) and O2 was delineated by optical emission spectroscopy, quadrupole mass spectrometry, transmission Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy. Hydrocarbons were the predominant contaminants in films obtained with only ZTB in the plasma, while their fractions decreased rapidly with the increasing O2 to ZTB-carrying Ar flow rate ratio (O2/Ar), and eventually became negligible in the oxygen-rich condition at O2/Ar⩾2. However, the increasing amount of oxygen led to the formation of hydrogen carbonate and formate from CO chemisorption at O2/Ar=0.5 to mostly bidentate carbonate from CO2 chemisorption at O2/Ar=2. The films from all conditions contained a significant amount of hydrogen-bonded hydroxyl groups. At higher O2/Ar ratios, the decrease in hydrocarbon concentration and the increase in carbonate fractions resulted in the increase in the dielectric constant and the negative oxide trapped charges.

Articles you may be interested inSurface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga-and Nface gallium nitride A plasma enhanced atomic layer deposition ͑PEALD͒ process was developed to deposit high-k dielectric constant materials using alternative metal t-butoxide and oxygen plasma exposures. The deposited thickness increased linearly with an increasing number of precursor/oxygen plasma cycles, and the growth rates of HfO 2 and ZrO 2 were determined to be 1.1 and 2.8 Å / cycle, respectively. The as-deposited films were determined to be fully oxidized and amorphous by the x-ray photoelectron spectroscopy ͑XPS͒ and Fourier transformed infrared spectroscopy ͑FTIR͒. The PEALD films were found to have high concentrations of bridging oxygen bonds with metals ͑M-O-M͒ as the film thickness increased, in contrast to the high concentrations of M-O-H in the films deposited by plasma enhanced chemical vapor deposition ͑PECVD͒. The M-O-M bonds in the PEALD films were further increased upon annealing at 250°C in atmosphere with a corresponding decrease in M-O-H concentrations, suggesting the elimination of hydroxyl groups upon annealing. The PEALD HfO 2 and ZrO 2 films showed higher dielectric constants ͑25, 22͒ than those of PECVD deposited films ͑21, 19͒, likely due to the enhanced ionic contribution from the M-O-M bonds in the PEALD films. The smallest equivalent oxide thickness ͑EOT͒ of 13 Å was achieved by PEALD HfO 2 with a leakage current density of 0.2 A / cm 2 , several orders of magnitude below that of thermally grown SiO 2 films with the same EOT.

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We present a methodology for real-time control of thin-film carbon content in a plasma-enhanced metal-organic chemical vapor deposition process using combination of online gas phase measurements obtained through optical emission spectroscopy and off-line (ex situ) measurements of film composition obtained via X-ray photoelectron spectroscopy (XPS). Initially, an estimation model of carbon content of ZrO 2 thin films based on real-time optical emission spectroscopy data is presented. Then, a feedback control scheme, which employs the proposed estimation model and a proportional-integral controller, is developed to achieve carbon content control. Using this approach, a real-time control system is developed and implemented on an experimental electron cyclotron resonance high-density plasma-enhanced chemical vapor deposition system to demonstrate the effectiveness of real-time feedback control of carbon content. Experimental results of depositions and XPS analysis of deposited thin films under both open-loop and closed-loop operations are shown and compared. The advantages of operating the process under real-time feedback control in terms of robust operation and lower carbon content are demonstrated.