The Use of Selective Polymerization of Poly(Methyl Methacrylate) for Area-Selective Masking of Nanoscale Semiconductors
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Nanowire transistor research has intensified in the past two decades due to the need for a novel idea to improve upon shortcomings associated with the modern transistor. A prevailing shortcoming in conventional transistor fabrication is limited throughput due to top-down fabrication steps such as lithography. One solution of interest is the nanowire heterostructure transistor which is fabricated in a bottom-up approach and leverages selective surface chemistry to controllably mask specific segments of the structure. The purpose of this work is to use polymers for selective surface chemical treatment on semiconductors enabling selective deposition or annealing of a dielectric by masking specific substrate chemistries. This occurs in a bottom-up fabrication process. The dielectric will act as the gate oxide for a nanowire transistor. Prior research has indicated that polymers can prevent various molecules from reaching a substrate surface due to their dense network. In this study, atom transfer radical polymerization is utilized to create a soft mask that is selective to silicon. The polymer of interest, poly(methyl methacrylate), is grown on initiating groups anchored to a silicon surface to attain a desired thickness. The intermediate steps are optimized for the best possible performance. The polymer is then subjected to atomic layer deposition with aluminum oxide to determine the stability of the polymer and its practicality as a mask for oxide deposition. These experiments may elucidate a method for gate oxide formation on a nanowire heterostructure. Success could have significant impact on this field and would be the next step to attaining functioning nanowire transistors for use in everyday devices.