Unique precursor delivery and control afforded by low-pressure pulsed-CVD process with ultrasonic atomization

The novel chemical vapor deposition system, termed Pulsed-CVD, employs timed liquid injection with ultrasonic atomization to deliver the precursor vapor to a low-pressure reactor. A description of the operating principles of Pulsed-CVD is given. Experimental results were analyzed to determine the rate controlling mechanisms and conversion efficiency. The system was studied using deposition of TiO₂, ZrO₂ and Yttra-Stabilized-Zirconia films from dilute solutions of metalorganic precursors. Growth rate was measured by in situ color fringe technique and derived from final film thickness over the temperature range 400°-650°C. Titania films up to 45μm in thickness were deposited at growth rates exceeding 0.5μm/min. YSZ films up to 17μm thick were deposited at a rate of 0.1 μm/min. Film microstructure was observed using optical microscope and SEM. Morphology was determined by XRD. Analysis shows that morphology, texture, and porosity, can be controlled by deposition tem perature and injection rate. Pulsed-CVD has demonstrated good performance, with uniform film thickness and relatively high growth rate and conversion efficiency.