UC Riverside

The ability to grow thin films on solid substrates through chemical deposition, such as atomic layer deposition (ALD), in an area-selective (AS) fashion is a hallmark of manufacturing processes within the semiconductor industry. One promising method to achieve this is through silylation – a method to passivate surfaces against chemical reactions using inhibitor molecules possessing substituted silyl moieties. These surface modifiers have traditionally been used ex-situ in the liquid-phase creating limitations for their integration into existing semiconductor process design due to their long reaction times and high costs involved at an industrial scale. Additionally, solvent effects present in the liquid phase may be detrimental to the quality of the organosilane monolayer. This research addresses these issues by employing an all gas-phase silylation process, affording the unique advantage of in-situ analysis combined with the ability to be integrated with other gas-phase microelectronics processing steps. Finally, this passivation scheme was evaluated in the context of AS-ALD of metal oxides. The nucleation delay and subsequent growth associated with the ALD of titania and hafnia thin films on silica surfaces silylated with N-(trimethylsilyl)dimethylamine (TMSDMA) in both the liquid and gas phase was characterized using X-ray photoelectron spectroscopy. Both silylation methods resulted in comparable passivation efficacies regardless of the starting surface or the ALD reactions used, demonstrating an intrinsic limitation to the extent of inhibition achievable. Moreover, a lower degree of carbon content was observed when using the gas-phase silylation approach suggestive of the formation of a higher quality monolayer. The interaction of TMSDMA with copper substrates was also investigated, in which it was determined that trimethylsilyl moieties did not chemisorb on copper under conditions that otherwise passivate silica. A simple AS-ALD scheme was developed to control the selective deposition of titania where the role of the growth and non-growth surface between copper and silica could be interchanged using TMSDMA. This modification scheme also shows promise in the field of heterogenous catalysis as it affords the ability to control the extent of silylation should partial blocking of surface hydroxyl nucleation sites be desired, which may be beneficial for the growth of immobilized nanoparticles.