SiO_2 film growth at low temperatures by catalyzed atomic layer deposition in a viscous flow reactor

摘要

SiO_2 thin films were grown by catalyzed atomic layer deposition (ALD) at low temperatures in a viscous flow reactor using sequential SiCl_4 and H_2O exposures. Pyridine (C_5H_5N) was used as a catalyst for both reactant exposures. Micropulsing was employed to avoid possible film contamination by pyridinium chloride. Quartz crystal microbalance experiments measured a SiO_2 film growth rate of 1.35 A per SiCl_4/H_2O AB cycle at 305 K with SiCl_4, H_2O and pyridine exposures of 10~3-10~4 Langmuir (1 Langmuir=10~(-6) Torr s). This SiO_2 ALD growth rate was verified by ex situ X-ray reflectivity, spectroscopic ellipsometry and surface profilometry measurements. The SiO_2 ALD film growth rate decreased dramatically at higher temperatures. Transmission Fourier transform infrared spectroscopy studies revealed that the hydrogen-bonded pyridine coverage was correlated with the catalyzed SiO_2 ALD growth rates from 305 to 360 K. Larger pyridine pressures were needed for catalyzed SiO_2 ALD at higher temperatures to offset the larger pyridine desorption rates. The SiO_2 ALD films contained negligible C, N, or Cl impurities as determined by X-ray photoelectron spectrometry. The deposited SiO_2 films were also extremely smooth with a surface roughness identical to the initial Si(100) substrate.