Low Temperature Direct Metal Bonding by Self Assembled Monolayers

2007 ◽  
Vol 990 ◽  
Author(s):  
Xiaofang Ang ◽  
Li Cheong Chin ◽  
Guo Ge Zhang ◽  
Jun Wei ◽  
Zhong Chen ◽  
...  
Keyword(s):  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Surface Passivation ◽  
Bonding Temperature ◽  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Assembled Monolayers ◽  
Thermocompression Bonding ◽  
Self Assembled

ABSTRACTElevated bonding temperature for interconnection deteriorates the reliability of both the device and the interconnect; hence the imperative for developing low temperature bonding methods. This study investigates the feasibility of using self-assembled monolayers (SAMs) to assist direct gold-gold bonding. This involves a simple molecular self-assembly process whereby a monolayer of alkyl chains with a sulfur end group is attached to the gold surface prior to thermocompression bonding. Using this method, we have achieved gold to gold bonding at a bonding temperature below 100°C, a significant reduction compared to the conventional bonding temperatures of above 150 °C. We attribute this temperature reduction to two properties of SAMs - (1) surface passivation of the Au surface that precludes adsorption of surface contaminants, and (2) The easy displacement of SAMs through thermal desorption just before bonding occurs. This SAMs-assisted bonding mechanism is supported by X-ray photoelectron spectroscopy (XPS) and surface plasmon resonance (SPR) results.

Tribology of PFPE Overcoated Self-Assembled Monolayers Deposited on Silicon Surface: Effect of Thermal Treatment

2005 ◽  
Author(s):  
N. Satyanarayana ◽  
S. K. Sinha
Keyword(s):  
Thermal Treatment ◽  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Surface Effect ◽  
Chemical Properties ◽  
Dip Coating ◽  
Self Assembled Monolayers ◽  
Wear Life ◽  
Assembled Monolayers ◽  
Self Assembled

Effect of thermal treatment on the friction and wear of monomolecular layers of SAMs (Self-assembled monolayers) overcoated with PFPE was studied using ball-on-disk tribometer. Two SAMs, Octadecyltrichlorosilane (OTS) and 3-aminopropyltrimethoxysilane (APTMS) were formed on the Si substrate by self-assembly followed by dip-coating with perfluoropolyether (PFPE). Modified Si samples are thermally treated at 150 °C under vacuum for 2h. The physical and chemical properties of modified samples, before and after thermal treatment, are analyzed using contact angle measurements, X-ray photoelectron spectroscopy (XPS). Tribological properties are evaluated using Universal Micro Tribometer (UMT). A Si3N4 ball of 4mm diameter is used as the counterface. Thermal treatment of the PFPE coated SAMs and Si surface reduced the coefficient of friction to slightly lower values in all cases. Thermal treatment has shown slight increase in wear life in the case of PFPE coated APTMS SAM surfaces whereas it decreased the wear life in the case of PFPE coated OTS SAM and Si surfaces. The exact reasons for this behavior are not clear at present, but it is being speculated that thermal treatment effects the extent of bonding between the surface groups of PFPE and SAMs and mobile characteristics of the PFPE, which finally influence the wear durability characteristics. Therefore, the differences in the wear durability characteristics are analyzed using changes in the surface energies and the amount of strongly adsorbed PFPE, as a result of thermal treatment.

Investigation of two-component mixed self-assembled monolayers on gold

2001 ◽  
Vol 79 (3) ◽  
pp. 328-336
Author(s):  
Zhen Wang ◽  
Yan-Li Shi ◽  
Hu-Lin Li
Keyword(s):  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Electrochemical Impedance ◽  
Impedance Analysis ◽  
Self Assembled Monolayers ◽  
X Ray ◽  
Molar Ratios ◽  
Two Component ◽  
Assembled Monolayers ◽  
Self Assembled

Two-component mixed self-assembled monolayers (SAMs) composed of 2-mercapto-5-methyl-1,3,4-oxadiazole (MMO) and 1-dodecanethiol (C12SH) in various molar percentages were prepared on gold surfaces by self-assembly. X-ray photoelectron spectroscopy (XPS) and wettability results gave evidence that the coverage of MMO was controlled by the composition of MMO in the assembling solution. The monolayer coverage and apparent rate constant of the redox active probes in solution of different molar ratios of mixed SAMs could be calculated using impedance measurements. The cyclic voltammetry reveals that the probes are selectively passed through the mixed SAMs depending upon their properties.Key words: self-assembled monolayers (SAMs), X-ray photoelectron spectroscopy (XPS), electrochemistry, electrochemical impedance analysis.

Self-Assembled Monolayers of Heme Derivatives on a Gold Surface

2000 ◽  
Vol 73 (9) ◽  
pp. 1993-2000 ◽  
Author(s):  
Kazutoshi Kobayashi ◽  
Shin'ichiro Imabayashi ◽  
Katsuhiko Fujita ◽  
Kazuhide Nonaka ◽  
Takashi Kakiuchi ◽  
...  
Keyword(s):  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Assembled Monolayers ◽  
Self Assembled

Spectral and cyclic voltammetric characterization of self-assembled monolayers on gold of pyrene end-labeled oligonucleotide duplexes

1999 ◽  
Vol 77 (5-6) ◽  
pp. 1077-1084 ◽  
Author(s):  
R Scott Reese ◽  
Marye Anne Fox
Keyword(s):  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Self Assembled Monolayer ◽  
Surface Emission ◽  
Assembled Monolayers ◽  
Oligonucleotide Duplex ◽  
Self Assembled ◽  
Duplex Formation

Self-assembled monolayers of sulfur-terminated oligonucleotide duplexes were formed on flat gold surfaces, either by exposure of a self-assembled monolayer bearing one oligonucleotide strand to the complementary strand or by preformation of a oligonucleotide duplex that was then deposited on a fresh gold surface. Virtually identical spectral behavior was observed whether the duplex was produced before deposition or by in situ complementary association. With a duplex bearing an appropriate pyrene end-label, the resulting thin film was photoresponsive. Surface emission measurements show no evidence for pyrene aggregation on the modified surfaces. The polarity of the photocurrent, reflecting photoinduced electron transfer initiated by photoexcitation of pyrene, is opposite that expected from the oligonucleotide-mediated reduction of the appended pyrene excited state.Key words: oligonucleotide, self-assembled monolayer, duplex formation, photoelectrochemistry, surface emission.

scholarly journals X-ray spectroscopy characterization of self-assembled monolayers of nitrile-substituted oligo(phenylene ethynylene)s with variable chain length

2012 ◽  
Vol 3 ◽  
pp. 12-24 ◽  
Author(s):  
Hicham Hamoudi ◽  
Ping Kao ◽  
Alexei Nefedov ◽  
David L Allara ◽  
Michael Zharnikov
Keyword(s):  
Chain Length ◽  
Photoelectron Spectroscopy ◽  
Self Assembled Monolayers ◽  
Phenylene Ethynylene ◽  
X Ray ◽  
Molecular Length ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Gold Thiolate

Self-assembled monolayers (SAMs) of nitrile-substituted oligo(phenylene ethynylene) thiols (NC-OPEn) with a variable chain length n (n ranging from one to three structural units) on Au(111) were studied by synchrotron-based high-resolution X-ray photoelectron spectroscopy and near-edge absorption fine-structure spectroscopy. The experimental data suggest that the NC-OPEn molecules form well-defined SAMs on Au(111), with all the molecules bound to the substrate through the gold–thiolate anchor and the nitrile tail groups located at the SAM–ambient interface. The packing density in these SAMs was found to be close to that of alkanethiolate monolayers on Au(111), independent of the chain length. Similar behavior was found for the molecular inclination, with an average tilt angle of ~33–36° for all the target systems. In contrast, the average twist of the OPEn backbone (planar conformation) was found to depend on the molecular length, being close to 45° for the films comprising the short OPE chains and ~53.5° for the long chains. Analysis of the data suggests that the attachment of the nitrile moiety, which served as a spectroscopic marker group, to the OPEn backbone did not significantly affect the molecular orientation in the SAMs.

scholarly journals Density Functional Theory with Modified Dispersion Correction for Metals Applied to Self-Assembled Monolayers of Thiols on Au(111)

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
M. P. Andersson
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Dimethyl Disulfide ◽  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Dispersion Correction ◽  
Dissociative Chemisorption ◽  
Functional Theory ◽  
Assembled Monolayers ◽  
Self Assembled

Using sound physical principles we modify the DFT-D2 atom pairwise semiempirical dispersion correction to density functional theory to work for metallic systems and in particular self-assembled monolayers of thiols on gold surfaces. We test our approximation for two functionals PBE-D and revPBE-D for lattice parameters and cohesive energies for Ni, Pd, Pt, Cu, Ag, and Au, adsorption energies of CO on (111) surfaces of Pd, Pt, Cu, Ag, and Au, and adsorption energy of benzene on Ag(111) and Au(111). Agreement with experimental data is substantially improved. We apply the method to self-assembled monolayers of alkanethiols on Au(111) and find reasonable agreement for PBE-D and revPBE-D for both physisorption of n-alkanethiols as well as dissociative chemisorption of dimethyl disulfide as an Au-adatom-dithiolate complex. By modifying the C6 coefficient for Au, we obtain quantitative agreement for physisorption and chemisorption for both PBE-D and revPBE-D using the same set of parameters. Our results confirm that inclusion of dispersion forces is crucial for any quantitative analysis of the thiol and thiolate bonds to the gold surface using quantum chemical calculations.

Interfacial Adhesion of Cu to Self-Assembled Monolayers on SiO2

2001 ◽  
Vol 695 ◽  
Author(s):  
G. Cui ◽  
M. Lane ◽  
K. Vijayamohanan ◽  
G. Ramanath
Keyword(s):  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Interfacial Adhesion ◽  
Adhesion Energy ◽  
Binding Energies ◽  
Self Assembled Monolayers ◽  
Chemical Binding ◽  
Barrier Materials ◽  
Assembled Monolayers ◽  
Self Assembled

ABSTRACTAs the critical feature size in microelectronic devices continues to decrease below 100 nm, new barrier materials of > 5 nm thickness are required. Recently we have shown that self-assembled monolayers (SAMs) are attractive candidates that inhibit Cu diffusion into SiO2. For SAMs to be used as barriers in real applications, however, they must also promote adhesion at the Cu/dielectric interfaces. Here, we report preliminary quantitative measurements of interfacial adhesion energy and chemical binding energy of Cu/SiO2 interfaces treated with nitrogen-terminated SAMs. Amine-containing SAMs show a ~10% higher adhesion energy with Cu, while interfaces with Cu-pyridine bonds actually show degraded adhesion, when compared with that of the reference Cu/SiN interface. However, X-ray photoelectron spectroscopy (XPS) measurements show that Cu-pyridine and Cu-amine interactions have a factor-of-four higher binding energy than that of Cu-N bonds at Cu/SiN interfaces. The lack of correlation between adhesion and chemical binding energies is most likely due to incomplete coverage of SAMs.

Self-Assembled Monolayers of Hexapeptides on Gold:  Surface Characterization and Orientation Distribution Analysis†

2004 ◽  
Vol 108 (45) ◽  
pp. 9673-9681 ◽  
Author(s):  
Xingu Wen ◽  
Richard W. Linton ◽  
Fernando Formaggio ◽  
Claudio Toniolo ◽  
Edward T. Samulski
Keyword(s):  
Surface Characterization ◽  
Gold Surface ◽  
Orientation Distribution ◽  
Self Assembled Monolayers ◽  
Distribution Analysis ◽  
Assembled Monolayers ◽  
Self Assembled

Specific Immobilization of Streptavidin on Mixed Self-Assembled Monolayers as Mixing Ratio

2007 ◽  
Vol 121-123 ◽  
pp. 495-498 ◽  
Author(s):  
Jun Hyung Park ◽  
Buyng Su Park ◽  
Gu Huh ◽  
Seung Hyun Lee ◽  
Hyun Sook Lee ◽  
...  
Keyword(s):  
Colorimetric Detection ◽  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Scanning Tunneling ◽  
Local Domain ◽  
Mixing Ratio ◽  
Tunneling Microscopy ◽  
Self Assembled Monolayer ◽  
Assembled Monolayers ◽  
Self Assembled

We report on the distribution of mixed self-assembled monolayers (SAMs) composed of biotinylated and diluent alkylthiolates for streptavidin immobilization. Two thiol derivatives, 11-mercapto-1-undecanol (MUOH) and 11-mercaptoundecanoic-(8-biotinylamido-3,6-dioxaoctyl) amide (MBDA), were employed for mixed SAM. These thiols formed self-assembled monolayer without local domain, and streptavidins were immobilized onto biotinylated gold surface without nonspecific binding. In order to find the optimized condition of immobilization of streptavidin, we controlled the mixing ratio of two kind thiols by colorimetric detection assay, and the immobilization was characterized by atomic force microscopy (AFM), scanning tunneling microscopy (STM), and ellipsometer.

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