MOCVD KINETICS OF STRONTIUM BISMUTH TANTALATE THIN FILM GROWTH
M. Šilinskas, M. Lisker, B. Kalkofen, S. Matichyn, and E. Burte
Institute of Micro- and Sensor Systems, Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany

Received 26 May 2004

Dedicated to the 100th anniversary of Professor K. Baršauskas

The thin films of BiO_x, Sr_xTa_yO_z, and strontium bismuth tantalate (SBT) were deposited by metalorganic chemical vapour deposition (MOCVD) 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 to 600 °C and from 0.35 to 7 mbar, respectively. Bi(/\//)₃ (triallyl bismuth) and Sr[Ta(OEt)₅(OC₂H₄OMe)]₂ (strontium bis[tantalum(pentaethoxy)(2-methoxyethoxide)] were used as a Bi precursor and as a Sr–Ta precursor, respectively. A liquid delivery system was used to supply and to evaporate the precursor 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 BiOx and Sr_xTa_yO_z was compared to the growth rate of SBT to obtain information about mutual interaction between precursors. The deposition rate of bismuth oxide thin films was low (∼10 nm/h at 0.35 mbar) and did virtually not depend on 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 the deposition rate of the single precursors. The growth rate significantly depends on pressure. The decrease of the deposition pressure in the reactor chamber reduces the deposition rate of BiO_x, Sr_xTa_yO_z, and SBT, but on the other hand, it improves the uniformity of the film thickness. The XPS measurements showed a deficit of bismuth in the SBT films even though the concentration of the Bi precursor was several times higher. The XPS depth-profiling by Ar⁺ ion sputtering indicated different bond characteristics of Ti, Sr, and Bi before and after ion beam bombardment.

STRONCIO BISMUTO TANTALATO DANGŲ AUGINIMO KINETIKA, NAUDOJANT METALOORGANINĮ CHEMINĮ GARŲ NUSODINIMO METODĄ
M. Šilinskas, M. Lisker, B. Kalkofen, S. Matichyn, E. Burte
Otto von Guericke universitetas, Magdeburgas, Vokietija

BiO_x, Sr_xTa_yO_z ir stroncio bismuto tantalato (SBT) dangos buvo sudaromos and 150 mm silicio (100) padėklo, naudojant metaloorganinį cheminį garų nusodinimo metodą iš Bi(/\//)₃ (trialilbismuto) ir iš Sr[Ta(OEt)₅(OC₂H₄OMe)]₂ (stroncio bis[tantalo (pentaetoksi)(2-metoksietoksido)]). Dangoms apibūdinti naudojome spektroskopinę elipsometriją ir Röntgen’o spindulių fotoelektronų spektroskopiją (RFS). Norint teisingai parinkti SBT auginimo sąlygas, iš pradžių tyrėme bismuto oksido bei stroncio tantalato auginimo kinetiką. Paaiškėjo, kad bismuto oksidas auga lėtai (∼10 nm/h, esant 0,35 mbar slėgiui), o jo auginimo sparta beveik nepriklauso nuo temperatūros. Priešingai, stroncio titanato auginimo sparta labai priklauso nuo temperatūros. SBT auginimo sparta buvo mažesnė nei BiO_x, Sr_xTa_yO_z, ir ji buvo būdingesnė BiO_x. Dangų auginimo sparta taip pat labai priklausė ir nuo slėgio kameroje: didėjant slėgiui, didėjo nusodinimo sparta, bet kartu didėjo ir plėvelės storio netolygumai. Naudojant RFS, parodyta, kad dangose trūksta bismuto, net jei Bi(/\//)₃ koncentracija du kartus didesnė už Sr[Ta(OEt)₅(OC₂H₄OMe)]₂ koncentraciją.