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

Abstract

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.

Structurally Defined Allyl Compounds of Main Group Metals: Coordination and Reactivity

“…The homoleptic allyl compounds of Group 15 with the general formula [M(C 3 H 5 ) 3 ] (M=As,106 Sb,107 Bi)108, 109, 110c are distillable liquids used for metalorganic chemical vapor deposition and related processes (see Section 5.5) 110. The main decomposition pathway is the coupling of allyl ligands to give 1,5‐hexadiene with concomitant formation of M 0 109.…”

“…A radical mechanism and an SbC 3 H 5 BDE of 21.6 kcal mol −1 were suggested for this process, although reductive coupling could not be ruled out. The higher homologue [Bi(C 3 H 5 ) 3 ] was investigated as a new liquid source of bismuth for MOCVD and low‐temperature (<300 °C) MOCVD of bismuth‐containing superconductor films, such as SrBi 2 Ta 2 O 9 110c,d. The decomposition of [Bi(C 3 H 5 ) 3 ] in solution gave 1,5‐hexadiene as the only detected organic decomposition product, thus suggesting a radical mechanism 109.…”

Enhanced ferroelectric properties of multilayer SBT-BTN thin films for NVRAM applications

“…The relationship between process parameter and composition of SBT films has been studied in previous work of our group [16]- [18] [24]. The XPS measurements of SBT and BTN films indicated an atomic composition of these films at various processing parameters.…”

“…Although perovskite type thin films SBT, BIT, and BTN have been extensively studied, no work on multilayer SBT and Nb 5+ -substituted BiT (BTN) thin films has yet been carried out. Therefore, we deposited SBT/BTN multilayer thin films with different stacking periodicities utilizing metal organic chemical vapor deposition process (MOCVD), optimized in our previous work [16]- [18].…”

Synthesis of Al2O3–SiO2 Films by Ar/O2 Plasma-Enhanced CVD from Alkoxide Precursors

“…[15] A series of monolithic, composite, and graded nitride, carbide, and oxide films have recently been synthesized from alkoxide solution precursors through a liquid-injection (LI), plasmaenhanced (PE)CVD technique. [16][17][18][19][20] This study is concerned with using Al and Si alkoxide precursors to synthesize monolithic alumina and silica, and their composite films, in a thermal oxygen plasma. Furthermore, the Al 2 O 3 and composite films are deposited on steel substrates and they have demonstrated superior protective ability in a high temperature KCl vapor/air atmosphere.…”