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Selective Atomic Layer Deposition Mechanism for Titanium Dioxide Films with (EtCp)Ti(NMe2)3: Ozone versus Water
Chemistry of Materials ( IF 8.6 ) Pub Date : 2018-01-16 00:00:00 , DOI: 10.1021/acs.chemmater.7b04790
Joseph P. Klesko 1 , Rezwanur Rahman 1 , Aaron Dangerfield 1 , Charith E. Nanayakkara 1, 2 , Thomas L’Esperance 1 , Daniel F. Moser 3 , L. Fabián Peña 1 , Eric C. Mattson 1 , Charles L. Dezelah 2 , Ravindra K. Kanjolia 2 , Yves J. Chabal 1
Affiliation  

The need for the conformal deposition of TiO2 thin films in device fabrication has motivated a search for thermally robust titania precursors with noncorrosive byproducts. Alkylamido-cyclopentadienyl precursors are attractive because they are readily oxidized, yet stable, and afford environmentally mild byproducts. We have explored the deposition of TiO2 films on OH-terminated SiO2 surfaces by in situ Fourier transform infrared spectroscopy using a novel titanium precursor [(EtCp)Ti(NMe2)3 (1), Et = CH2CH3] with either ozone or water. This precursor initially reacts with surface hydroxyl groups at ≥150 °C through the loss of its NMe2 groups. However, once the precursor is chemisorbed, its subsequent reactivities toward ozone and water are very different. There is a clear reaction with ozone, characterized by the formation of monodentate formate and/or chelate bidentate carbonate surface species; in contrast, there is no detectable reaction with water. For the ozone-based ALD process, the surface formate/carbonate species react with the NMe2 groups during the subsequent pulse of 1, forming Ti—O—Ti bonds. Ligand exchange is observed within the 250–300 °C ALD window. X-ray photoelectron spectroscopy confirms the deposition of stoichiometric TiO2 films with no detectable impurities. For the water-based process, ligand exchange is not observed. Once 1 is adsorbed, there is no spectroscopic evidence for further reaction. However, there is still TiO2 deposition under typical ALD conditions. Co-adsorption experiments with controlled vapor pressures of water and 1 indicate that deposition arises solely from 1/water gas-phase reactions. This striking lack of reactivity between chemisorbed 1 and water is attributed to the electronic and steric effects of the EtCp group and facilitates the observation of gas-phase reactions.

中文翻译:

(EtCp)Ti(NMe 23的二氧化钛薄膜的选择性原子层沉积机理:臭氧对水

器件制造中对TiO 2薄膜的保形沉积的需求促使人们寻求具有非腐蚀性副产物的热坚固的二氧化钛前体。烷基酰胺基-环戊二烯基前体是有吸引力的,因为它们易于氧化,但稳定,并提供对环境温和的副产物。我们已经探索TiO 2的沉积2层薄膜上OH封端的SiO 2通过原位表面使用一种新的钛前体傅里叶变换红外光谱[(ETCP)的Ti(NME 231),等= CH 2 CH 3]与臭氧或水。该前体最初会通过失去其NMe 2基团而与≥150°C的表面羟基反应。但是,一旦前体被化学吸附,其随后对臭氧和水的反应性就会大为不同。与臭氧有清晰的反应,其特征是形成单齿甲酸盐和/或螯合双齿碳酸盐表面物质;相反,没有可检测到的与水发生反应。对于基于臭氧的ALD过程,表面甲酸盐/碳酸盐物质在随后的1脉冲期间与NMe 2基团反应,形成Ti-O-Ti键。在250–300°C的ALD窗口内观察到配体交换。X射线光电子能谱证实了化学计量的TiO 2的沉积膜中没有可检测到的杂质。对于水基工艺,未观察到配体交换。一旦吸附了1,就没有光谱学证据进一步反应。然而,在典型的ALD条件下仍然存在TiO 2沉积。在水和水蒸气压为1的情况下进行的共吸附实验表明,沉积仅来自1 /水气相反应。化学吸附的1与水之间这种显着的反应性缺乏归因于EtCp基团的电子和空间效应,有助于观察气相反应。
更新日期:2018-01-16
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