Activation of Surface Hydroxyl Groups by Modification of H-Terminated Si(111) Surfaces

Thissen, Peter; Peixoto, Tatiana; Longo, Roberto C.; Peng, Weina; Schmidt, Wolf Gero; Cho, Kyeongjae; Chabal, Yves J.

doi:10.1021/ja300270w

Cited by 70 publications

(76 citation statements)

References 37 publications

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“…Figure (bottom line) shows all of the typical spectral features of a monodentate phosphonic acid:11, 26–28 the stretch mode of the (P = O) at 1227 cm −1 , the asymmetric and symmetric stretch modes of the (P–O) at 1078 and 1004 cm −1 , and the deformation mode of the (P–O–H) feature clearly present at 956 cm −1 29. In the aliphatic region, the spectral positions of the strong asymmetric and symmetric stretch modes of the (CH 2 ) at 2918 and 2850 cm −1 , respectively, indicate an ordered arrangement on the surface.…”

Section: Resultsmentioning

confidence: 97%

“…Our calculations indicate that the monodentate configuration is the only chemisorption geometry possible for MPA adsorption on this oxide‐free H‐terminated Si(111) surface. The energy associated with bi‐ and tri‐dentate is substantially higher due to large strains needed to link three H centers separated by 3.9 Å to the oxygen atoms of the phosphonic acid head separated by 2.3 Å 31…”

Section: Resultsmentioning

confidence: 99%

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Monolayer Doping via Phosphonic Acid Grafting on Silicon: Microscopic Insight from Infrared Spectroscopy and Density Functional Theory Calculations

Longo

Cho

Schmidt

et al. 2013

Adv Funct Materials

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Monolayer doping (MLD) is a promising technique for creating ultra shallow junctions (USJs). Here, a novel self assembled monolayer (SAM) grafting technique is proposed through a single oxygen atom capable of MLD. Consequently, this approach can use simple forms of alkylphosphonic acids and avoid carbon contamination altogether during the doping process. In this paper, density functional theory (DFT) is used to explore the way how alkylphosphonic acid molecules can in just one chemical step be grafted on H-terminated Si(111). A maximum coverage of alkylphosphonic acids is found at 2/3 due to steric constrain forces. It is further demonstrated by means of in situ infrared spectroscopy and DFT calculations that the weak link of an alkylphosphonic acid, such as octadecylphosphonic acid (ODPA), is the P-C bond, with typical release of the carbon ligand around 500 ° C. Finally, after release of the carbon ligand, an unsaturated electron confi guration is driving force for the phosphorous to start the MLD process.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Monolayer Doping via Phosphonic Acid Grafting on Silicon: Microscopic Insight from Infrared Spectroscopy and Density Functional Theory Calculations

Longo

Cho

Schmidt

et al. 2013

Adv Funct Materials

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“…45 These computational setups are expected to yield vibrational frequencies within 20 cm −1 of the experimental values for the thymine CO stretching modes (Table1), 50 cm −1 for the phosphate PO modes, and 30 cm −1 for the phosphate P− O−H bending modes. 52 Note that, in this paper, the theoretical calculations only concern isolated dTMP and dTMP interacting with alumina.…”

Section: Methodsmentioning

confidence: 99%

Role of Alumina Coatings for Selective and Controlled Bonding of DNA on Technologically Relevant Oxide Surfaces

et al. 2015

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DNA immobilization on surfaces is crucial to a number of applications. However, detailed understanding of DNA/surface chemistry remains poorly documented, especially on oxide surfaces, due to the complexity of such large molecules. This work focuses on a simpler molecule, 2-deoxythymidine-5-monophosphate (dTMP), which contains all the chemical elements of DNA. It confirms that adsorption of dTMP onto OH-terminated SiO 2 surfaces does not result in a chemical bond (dTMP readily washes off) and instead shows that dTMP chemically adsorbs on Al 2 O 3 surfaces. We combine first-principles calculations, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy to determine the bonding configuration of dTMP onto alumina surfaces controllably grown by atomic layer deposition. We demonstrate that dTMP covalently reacts with alumina. Calculations indicate that covalent bonding of all dTMP polar groups (sugar ring, phosphate group, and thymine) is thermodynamically favored. Spectroscopic data and theory-based assignments of vibrational modes show that the bonding takes place primarily through both the thymine and phosphate groups. The reactivity and the tendency for dTMP to lie flat on the surface lead to an irreversible and disorganized dTMP layering. Studies of dTMP adsorption as a function of Al 2 O 3 thickness show that the density of grafted dTMP can be controlled, with measurable amounts even above the Al 2 O 3 monolayer coverage. These findings provide technological directions for DNA-based nanotechnologies to graft DNA on surfaces that would otherwise be unreactive.

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“…CuO, Cu 2 O and Cu, 13, 14 but it does not chemically attach on a SiO 2 surface at room temperature. [15][16][17][18][19] Hence, based on this intrinsically selective adsorption, area selective ALD of ZnO on ODPA-treated Cu/SiO 2 patterned substrates has been achieved for film thicknesses up to 36 nm. 20 However, even with a successful system like ODPA on Cu/SiO 2 , there are several factors limiting the use of SAM passivation layers for area selective ALD.…”

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confidence: 99%

Self-Correcting Process for High Quality Patterning by Atomic Layer Deposition

2015

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Nanoscale patterning of materials is widely used in a variety of device applications. Area selective atomic layer deposition (ALD) has shown promise for deposition of patterned structures with subnanometer thickness control. However, the current process is limited in its ability to achieve good selectivity for thicker films formed at higher number of ALD cycles. In this report, we demonstrate a strategy for achieving selective film deposition via a self-correcting process on patterned Cu/SiO2 substrates. We employ the intrinsically selective adsorption of octadecylphosphonic acid self-assembled monolayers on Cu over SiO2 surfaces to selectively create a resist layer only on Cu. ALD is then performed on the patterns to deposit a dielectric film. A mild etchant is subsequently used to selectively remove any residual dielectric film deposited on the Cu surface while leaving the dielectric film on SiO2 unaffected. The selectivity achieved after this treatment, measured by compositional analysis, is found to be 10 times greater than for conventional area selective ALD.

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Activation of Surface Hydroxyl Groups by Modification of H-Terminated Si(111) Surfaces

Cited by 70 publications

References 37 publications

Monolayer Doping via Phosphonic Acid Grafting on Silicon: Microscopic Insight from Infrared Spectroscopy and Density Functional Theory Calculations

Monolayer Doping via Phosphonic Acid Grafting on Silicon: Microscopic Insight from Infrared Spectroscopy and Density Functional Theory Calculations

Role of Alumina Coatings for Selective and Controlled Bonding of DNA on Technologically Relevant Oxide Surfaces

Self-Correcting Process for High Quality Patterning by Atomic Layer Deposition

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