METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION OF ZRO2 FILMS USING ZR(THD)4 AS PRECURSORS

Synthesis of zirconium tetramethylheptanedione [Zr(thd)4] was optimize d. Purity of Zr(thd)4 was confirmed by melting point determination, ca rbon, and hydrogen elemental analysis and proton nuclear magnetic reso nance spectrometer (NMR). By using Zr(thd)4, excellent quality ZrO2 th in films were successfully deposited on single-crystal silicon wafers by metal-organic chemical vapor deposition (MOCVD) at reduced pressure s. For substrate temperatures below 530-degrees-C, the film deposition rates were very small (less-than-or-equal-to 1 nm/min). The film depo sition rates were significantly affected by (i) source temperature, (i i) substrate temperature, and (iii) total pressure. As-deposited films are carbon free. Furthermore, only the tetragonal ZrO2 phase was iden tified in as-deposited films. The tetragonal phase transformed progres sively into the monoclinic phase as the films were subjected to a high -temperature post-deposition annealing. The optical properties of the ZrO2 thin films as a function of wavelength, in the range of 200 nm to 2000 nm, were also reported. In addition, a simplified theoretical mo del which considers only a surface reaction was used to analyze the de position of ZrO2 films. The model predicated the deposition rates well for various conditions in the hot wall reactor.