EFFECT OF DEPOSITION TEMPERATURE ON DIELECTRIC-PROPERTIES OF PECVD TA2O5 THIN-FILM

Tantalum oxide film formation by plasma-enhanced chemical vapour deposition (PECVD) using TaCl5 as a source material was examined. The effects of deposition temperature on the formation, structure and electric properties of the Ta2O5 film were investigated for Al/Ta2O5/p-Si (MTS) capacitors. The deposition rate and refractive index increased with increasing deposition temperature. It was found that the structure of Ta2O5 deposited by PECVD was amorphous as-deposited. However, crystalline delta-Ta2O5 of hexagonal structure was formed by a 700 degrees C, 1 h heat treatment in argon. Capacitance and relative dielectric constant of the PECVD Ta2O5 were found to be 2.54 fF mu m(-2) and 23.5, respectively. The PECVD films obtained in this study have higher dielectric constants and remarkably better general film characteristics than those obtained by other deposition methods.