Synthesis of New Liquid Mixed Sr-Ta and Sr-Nb Alkoxides as CVD Precursors for Metal Oxide Thin Films

Abstract

tantalum alkoxides, can be used as a precursor to grow tantalum oxide thin films by CVD for device application. Using this precursor, a Ta 2 O 5 film with a thickness of 180 nm had a leakage current density below 1´10 ±8 A cm ±2 for an electric field strength of 2 MV cm ±1 , and a breakdown voltage of 3 MV cm ±1 . The dielectric constant was 22. Further optimization of the process could lead to tantalum oxide thin films with better electric properties. Investigation is in progress. ExperimentalThe CVD experiment was carried out in a cold-wall low-pressure reactor with a base pressure of 1´10 ±5 torr. TBTDET was vaporized at 313 K using Ar flowing at 10 sccm as the carrier gas. The deposition of thin films on p-Si(100) was carried out at temperatures between 573 K and 873 K. With oxygen flowing at 200 sccm, the pressure during the deposition was maintained at 1 torr.

Liquid-Delivery Metal–Organic CVD of Strontium Bismuth Tantalate Thin Films Using Sr[Ta(OC2H5)5(OC2H4OCH3)]2 and Bi(C6H5)3 Precursors

“…Sr[Ta(OC 2 H 5 ) 5 (O-C 2 H 4 OCH 3 )] 2 is another bimetallic alkoxide precursor. [13] The Sr/Ta atomic ratio in this source matches the stoichiometric composition of SBT films. Furthermore, it has a high vapor pressure (0.23 torr/190 C) and a wide control window of deposition temperature.…”

Crystal Structure of Bi(OCMe2CH2OMe)3 and Its Use in the MOCVD of Bi2O3

“…Conventional precursors include Sr(thd) 2 (thd = 2,2,6,6-tetramethylheptane-3,5-dionate), Bi(C 6 H 5 ) 3 , Bi(thd) 3 , and Ta(OEt) 5 or Ta(O i Pr) 4 (thd), [7,8] but these are generally incompatible, having very different physical properties and decomposition characteristics, resulting in poor oxide layer uniformity. This problem has been partially alleviated by the use of Sr±Ta and Sr±Nb heterometal alkoxides, such as Sr[Ta(OEt) 6 ] 2 , [9] Sr[Nb(OEt) 6 ] 2 , [9] Sr[Ta(OEt) 5 (dmae)] 2 [10,11] (dmae = OCH 2 CH 2 NMe 2 ), and Sr[Ta(OEt) 5 (OCH 2 CH 2 OMe)] 2 , [12] which largely overcome the mismatch between the Sr and Ta precursors, but there remains an urgent requirement for a compatible Bi precursor. The conventional sources Bi(C 6 H 5 ) 3 and Bi(thd) 3 are incompatible with Sr±Ta and Sr±Nb alkoxides, having significantly higher thermal stability.…”

Liquid injection MOCVD and ALD studies of “single source” Sr-Nb and Sr-Ta precursors

“…Studies in other laboratories confirm that, in contrast to [Sr{Ta(OPr i ) 6 } 2 ], the Sr:Ta mole ratio remains constant during the distillation of [Sr{Ta(OEt) 5 (mee)} 2 ] [13]. Studies in other laboratories confirm that, in contrast to [Sr{Ta(OPr i ) 6 } 2 ], the Sr:Ta mole ratio remains constant during the distillation of [Sr{Ta(OEt) 5 (mee)} 2 ] [13].…”