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Short-chain aminosilanes, namely, bis(N,Ndimethylamino)dimethylsilane (DMADMS) and (N,Ndimethylamino)trimethylsilane (DMATMS), have been used as Si precursors for atomic layer deposition (ALD) of SiO 2 . In this work, the DMADMS and DMATMS Si precursors are utilized as inhibitors for area-selective ALD (AS-ALD). The inhibitors selectively adsorb on a SiO 2 surface but not on H− Si, so that SiO 2 becomes selectively deactivated toward subsequent ALD. The deactivation of the SiO 2 surface by the inhibitors was investigated using various experimental and theoretical methods, including surface potential measurements, spectroscopic ellipsometry, and X-ray photoelectron spectroscopy. Better inhibition was observed for ALD of Ru and Pt than for ALD of Al 2 O 3 and HfO 2 . Through quantum mechanical and stochastic simulations, the difference in the blocking ability for noble metal and metal oxide ALD by the aminosilane inhibitors could be attributed to the inherently partial surface coverage by the inhibitors at their saturation and the reactivity of the subsequent ALD precursors. As silane inhibitors can be easily integrated with vacuum-based processes to facilitate high volume manufacturing of upcoming electronic devices, the current study provides a potential approach for the utilization of AS-ALD in pattern fabrication inside 3D nanostructures.

Indium gallium oxide (IGO) thin films were deposited via atomic layer deposition (ALD) using [1,1,1-trimethyl-N-(trimethylsilyl)silanaminato]indium (InCA-1) and trimethylgallium (TMGa) as indium and gallium precursors, respectively, and hydrogen peroxide as the reactant. To clearly understand the mechanism of multicomponent ALD growth of oxide semiconductor materials, several variations in the precursor-reactant deposition cycles were evaluated. Gallium could be doped into the oxide film at 200 °C when accompanied by an InCA-1 pulse, and no growth of gallium oxide was observed without the simultaneous deposition of indium oxide. Density functional theory calculations for the initial adsorption of the precursors revealed that chemisorption of TMGa was kinetically hindered on hydroxylated SiO but was spontaneous on a hydroxylated InO surface. Moreover, the atomic composition and electrical characteristics, such as carrier concentration and resistivity, of the ALD-IGO film were controllable by adjusting the deposition supercycles, composed of InO and GaO subcycles. Thus, ALD-IGO could be employed to fabricate active layers for thin-film transistors to realize an optimum mobility of 9.45 cm/(V s), a threshold voltage of -1.57 V, and a subthreshold slope of 0.26 V/decade.

The adsorption behavior of two bifunctional molecules, hydroquinone (HO–C6H4–OH) and p-benzoquinone (OC6H4O), on the germanium (100) surface is studied. A combination of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy experiments together with density functional theory calculations were used to identify the products. The distinct functionalities of the reactants result in different reaction pathways, namely, OH dissociation for hydroquinone and cycloaddition for p-benzoquinone. Yet, the major product formed, a dually tethered surface hydroquinoxy group with an aromatic ring (−OC6H4O–), is the same for both molecules. Dual dissociation of hydroquinone was highly selective in stereochemical configuration. Minor singly tethered products are also found for both precursors. The results suggest that selective attachment of aromatic groups on semiconductor surfaces can be achieved by choosing proper functionalities of the reactants.

Thermal atomic layer deposition (ALD) of metal has generally been achieved at high temperatures of around 300°C or at relatively low temperatures with highly reactive counter reactants, including plasma radicals and O 3 , which can induce severe damage to substrates. Here, the growth of metallic Pt layers by ALD at a low temperature of 80°C is achieved by using [(1,2,5,6-η)-1,5-hexadiene]-dimethyl-platinum(II) (HDMP) and O 2 as the Pt precursor and counter reactant, respectively. ALD results in the successful growth of continuous Pt layers at the low temperature without any reactive reactants owing to the low activation energy of the HDMP precursor for surface reactions. Because of the high reactivity of the precursor, the growth of a pure Pt layer is achieved on various thermally weak substrates, leading to the fabrication of high-performance conductive cotton fibers by ALD. A capacitive-type textile pressure sensor is successfully demonstrated by stacking elastomeric rubber-coated conductive cotton fibers perpendicularly and integrating them onto a fabric with a 7 × 8 array configuration to identify the features of the applied pressure, which can be effectively utilized as a new platform for future wearable and textile electronics. INTRODUCTIONAtomic layer deposition (ALD) has widely attracted considerable interest for various high technologies, such as semiconductor devices and display devices, 1-3 because of its superb ability to deposit ultrathin films with excellent controllability and conformality even on complex three-dimensional (3D) structures. 1-8 Based on these superior properties, ALD has been intensively studied for several applications. In particular, textile electronics using the ALD is one of the promising fields since several materials can be readily deposited at temperatures lower than 150°C by ALD, leading to the effective functionalization of thermally fragile substrates such as plastics, cellulose papers and polymeric textiles. [9][10][11][12] Chen et al. 13 demonstrated hydrophobic silk fabrics with a high laundering durability and robustness due to a TiO 2 coating deposited by ALD. However, in the case of metal ALD, since temperatures as high as 300°C are generally required to achieve successful deposition with the thermal energy of the precursor reactions, it is difficult to deposit conformal metal films onto thermally weak substrates using ALD, causing difficulties in a wide range of applications, including textile electronics. 14,15 To ensure successful metal ALD at low temperatures, ALD in which the

Area-selective atomic layer deposition (AS-ALD) is a promising bottom-up patterning approach for fabricating conformal thin films. One of the current challenges with respect to AS-ALD is the deficiency of the surface inhibitor used for fabricating nanoscale three-dimensional structures. In this study, a vapor-deliverable small inhibitor called ethanethiol (ET) that thermally adsorbs on surfaces was used for the AS-ALD of Al2O3. The inhibitor selectively adsorbed on Co and Cu substrates but not on the SiO2 substrate, allowing for the selective deactivation of Co and Cu substrates in Al2O3 ALD. The use of dimethylaluminum isopropoxide (DMAI) as the Al precursor resulted in better inhibition than the use of trimethylaluminum (TMA). Various experimental and theoretical methods, including water contact angle measurements, spectroscopic ellipsometry, X-ray photoelectron spectroscopy, density functional theory calculations, and Monte Carlo simulations, were used to elucidate the process of AS-ALD using ET. Dimerization of the DMAI precursor is considered to be a governing factor for its high deposition selectivity, while the probability of this phenomenon is very low for the TMA precursor. The current study provides insight into the selectivity of AS-ALD from the perspective of the chemical reaction and an opportunity to improve selectivity via precursor selection.

Adsorption of bifunctional molecules is important for chemical modification of semiconductor surfaces, since such molecules can be used to alter the terminal functionality. In this work, the effect of coverage in the reaction of catechol (1,2-benzenediol) and resorcinol (1,3-benzenediol) with the (100) surface of germanium is investigated by surface spectroscopy experiments and theoretical methods. The benzenediols are site-specifically adsorbed on the Ge surface dimers through dissociative adsorption of either one or two of the −OH groups. Infrared spectroscopy and density functional theory results suggest that the dually tethered products selectively assume certain geometrical configurations at the surface. Infrared and X-ray photoelectron spectroscopies reveal that singly tethered species become increasingly prevalent as the coverage approaches saturation. Monte Carlo simulations that account for specific binding configurations and interadsorbate interactions, identified through density functional theory calculations, quantitatively reproduce the experimentally observed coverage-dependence of singly and dually tethered adsorbates for both benzenediols. Our results indicate that the singly bound adsorbates with unreacted hydroxyls appear on the reactive pristine Ge surface due to a limitation of available adjacent reaction sites, and show that interadsorbate interactions play a major role in determining reaction product distributions.

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