Liquid‐Delivery MOCVD of Strontium Bismuth Tantalate Thin Films Using Sr[Ta(OC₂H₅)₅(OCH₂CH₂OCH₃)]₂ and Liquid Bi(CH₂CH=CH₂)₃ as Precursors

Thin films of BiO X , Sr X Ta Y O Z , and strontium bismuth tantalate (SBT) were deposited by metal‐organic (MO)CVD on 150 mm silicon (100) wafers. Some of the wafers were pre‐deposited with Pt electrodes. The substrate temperature and the deposition pressure were varied from 300 °C to 600 °C and from 0.35 mbar to 7 mbar, respectively. Bi(CH 2 CH=CH 2 ) 3 (triallylbismuth) and Sr[Ta(OEt) 5 (OC 2 H 4 OMe)] 2 (strontium‐bis[tantalum(pentaethoxide)(2‐methoxyethoxide)]) were used as Bi precursor and as Sr‐Ta precursor, respectively. A liquid delivery system was used to supply and to vaporize the precursors into the reactor. X‐ray photoelectron spectroscopy (XPS) and ellipsometry were carried out to characterize the film properties. The growth rate of the MOCVD of BiO X and Sr X Ta Y O Z was compared to the growth rate of SBT to obtain information about mutual interaction between the precursors. The deposition rate of bismuth oxide thin films was low (∼10 nm h –1 at 0.35 mbar) and virtually independent of the temperature. On the contrary, the growth rate of strontium tantalate films depended strongly on the temperature. The deposition rate of the SBT films was similar to the bismuth oxide film deposition, which slightly increased with increasing substrate temperature. However, the deposition rate of SBT was always lower than deposition rate of the single precursors. The growth rate significantly depended on pressure. The decrease of the deposition pressure in the reactor chamber reduced the deposition rate of BiO X , Sr X Ta Y O Z , and SBT but on the other hand, it improved the uniformity of the film thickness. XPS measurements showed a deficit of bismuth in the SBT films even though the concentration of the Bi precursor had been several times higher than the concentration of Sr‐Ta precursor. The XPS depth‐profiling by Ar + ion sputtering indicated more metallic bond characteristics of Ti, Sr, and Bi after ion‐beam bombardment.