Marcus K. Weldon
Alcatel-Lucent
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Marcus K. Weldon.
Journal of Vacuum Science & Technology B | 1997
Marcus K. Weldon; V. E. Marsico; Yves J. Chabal; A. Agarwal; D. J. Eaglesham; J. Sapjeta; W. L. Brown; D. C. Jacobson; Y. Caudano; S. B. Christman; E.E. Chaban
We have investigated the fundamental mechanism underlying the hydrogen-induced exfoliation of silicon, using a combination of spectroscopic and microscopic techniques. We have studied the evolution of the internal defect structure as a function of implanted hydrogen concentration and annealing temperature and found that the mechanism consists of a number of essential components in which hydrogen plays a key role. Specifically, we show that the chemical action of hydrogen leads to the formation of (100) and (111) internal surfaces above 400 °C via agglomeration of the initial defect structure. In addition, molecular hydrogen is evolved between 200 and 400 °C and subsequently traps in the microvoids bounded by the internal surfaces, resulting in the build-up of internal pressure. This, in turn, leads to the observed “blistering” of unconstrained silicon samples, or complete layer transfer for silicon wafers joined to a supporting (handle) wafer which acts as a mechanical “stiffener.”
Applied Physics Letters | 1998
Marcus K. Weldon; M. Collot; Yves J. Chabal; V.C. Venezia; Aditya Agarwal; T. E. Haynes; D. J. Eaglesham; S. B. Christman; E.E. Chaban
Infrared spectroscopy and secondary ion mass spectrometry are used to elucidate the mechanism by which co-implantation of He with H facilitates the shearing of crystalline Si. By studying different implant conditions, we can separate the relative contributions of damage, internal pressure generation, and chemical passivation to the enhanced exfoliation process. We find that the He acts physically as a source of internal pressure but also in an indirect chemical sense, leading to the reconversion of molecular H2 to bound Si–H in “VH2-like” defects. We postulate that it is the formation of these hydrogenated defects at the advancing front of the expanding microcavities that enhances the exfoliation process.
Surface Science | 1996
Marcus K. Weldon; V.E. Marsico; Yves J. Chabal; D.R. Hamann; S. B. Christman; E.E. Chaban
Abstract In this paper, we review our recent infrared studies of the fundamental physical and chemical processes occurring at the interface of bonded silicon wafers, as a function of surface preparation and annealing temperature. We present a brief overview of the practical aspects of silicon-wafer bonding and the techniques used to evaluate the interface integrity, which highlight the need for fundamental studies of the microscopic interface phenomena. Importantly, we show that the interface between two silicon wafers approximates an ideal spectroscopic environment, in that there is a 28-fold enhancement in the sensitivity to the normal component of the interface absorption over any other surface optical geometry. Furthermore, the interface region is almost infinitely stable at room temperature, but can exhibit partial pressures ranging from near vacuum to several atmospheres upon annealing. We present results for two distinct types of wafer bonding: hydrophobic (hydrogen-terminated) and hydrophilic (oxide-terminated), since the origin of the initial attraction between the opposing surfaces is quite different in the two cases. Specifically, we show that ideally hydrogen-terminated Si(111) surfaces come within a few A, under the influence of a Van der Waals attraction, as evidenced by a pronounced perturbation of the isolated SiH stretch mode. In contrast, the initial attraction between hydrophilic surfaces is via hydrogen bonding, which is mediated by the presence of 2–4 monolayers of water that are trapped at the interface upon room-temperature joining. We demonstrate that vibrational spectroscopy provides unprecedented mechanistic insight into the thermal evolution of the molecular interface, which necessarily has a profound influence on the bonding process. Throughout the paper, emphasis is given to the need for a wide variety of additional (fundamental) studies of the surface phenomena occurring in these novel, technologically important systems.
Journal of Chemical Physics | 2000
Marcus K. Weldon; K. T. Queeney; Alejandra B. Gurevich; Boris Stefanov; Yves J. Chabal; Krishnan Raghavachari
Surface infrared spectroscopy and density functional cluster calculations are used to study the thermal and atomic hydrogen-induced decomposition of water molecules on the clean Si(100)-(2×1) surface. We report the first observation of the Si–H bending modes associated with the initial insertion of oxygen into the dimer and backbonds of a silicon dimer. We find that, while one and two oxygen-containing dimers are formed almost simultaneously during the thermal decomposition of water on this surface, atomic H can be used to drive the preferential formation of the singly oxidized dimer. This work highlights the sensitivity of Si–H bending modes to the details of local chemical structure in an inhomogeneous system, suggesting that the combined experimental and theoretical approach demonstrated herein may be extremely useful in studying even more complex systems such as the hydrogenation of defects in SiO2 films.
Physica B-condensed Matter | 1999
Yves J. Chabal; Marcus K. Weldon; Y. Caudano; Boris Stefanov; Krishnan Raghavachari
Abstract In this paper, we review the pivotal role that defects (in particular vacancy structures) play in driving the H-induced exfoliation of Si. We highlight the central role that infrared spectroscopy has played in delineating the microscopic details of the exfoliation process. We show that when the results of such spectroscopic studies are combined with those obtained using a variety of other experimental probes as well as ab initio quantum chemical cluster calculations, an unambiguous mechanistic picture emerges. Specifically we find that H-terminated vacancy structures drive the formation of internal surfaces into cracks where H2 is then evolved, resulting in the build-up of sufficient internal pressure to cause lift-off of the overlying Si. The role of coimplantation of He is also discussed.
Materials Science in Semiconductor Processing | 1999
Alain C. Diebold; David Venables; Yves J. Chabal; David A. Muller; Marcus K. Weldon; Eric Garfunkel
Abstract The thickness of silicon dioxide that is used as the transistor gate dielectric in most advanced memory and logic applications has decreased below 7 nm. Unfortunately, the accuracy and reproducibility of metrology used to measure gate dielectric thickness during manufacture of integrated circuits remains in some dispute. In addition, detailed materials characterization studies have resulted in a variety of descriptions for the oxide-interface–substrate system. Part of the problem is that each method measures a different quantity. Another related issue concerns how one should define and model the critical dielectric/substrate interface. As scaling continues, the interface between silicon dioxide and silicon becomes a larger part of the total thickness of the oxide film. Although materials characterization studies have focused on this interface, there have been few attempts to compare the results of these methods based on an understanding of the models used to interpret the data. In this review, we describe the physical and electrical characterization of the interfacial layer. Infrared absorption data are reviewed and previous interpretations of the LO/TO phonon shifts as a function of oxide thickness are refined. We correlate the available results between physical methods and between physical and electrical methods. This information is essential to inclusion of an interfacial layer in optical models used to measure silicon dioxide inside the clean room. We also describe some characterization issues for nitrided oxides.
Surface Science | 2002
Marcus K. Weldon; K. T. Queeney; Joseph Eng; Krishnan Raghavachari; Yves J. Chabal
Abstract Due to the extreme dimensional scaling required by Moores law, Si device technology is increasingly subject to the limitations imposed by the intrinsic physics and chemistry of surfaces and interfaces. In this review we outline ways in which fundamental surface science has contributed an understanding to the microelectronics community and discuss areas where surface science may impact future development. We focus on the example of silicon dioxide (SiO2) on silicon, since this interface lies at the heart of modern transistor technology and has therefore received a great deal of attention in recent years. We highlight a number of experimental and theoretical approaches that have elucidated the fundamental phenomena associated with the formation and evolution of this critical technological interface, revealing the remarkable interdependence of science and technology that now characterizes this rapidly evolving industry.
Journal of Vacuum Science & Technology B | 1999
Marcus K. Weldon; K. T. Queeney; Yves J. Chabal; Boris Stefanov; Krishnan Raghavachari
The microscopic mechanism of the formation of ultrathin oxides on Si(100) has been investigated using a combination of infrared spectroscopy and ab initio quantum chemical cluster calculations. The 0→2 monolayer oxide films are grown sequentially from the “bottom-up” using repeated water exposures and annealing cycles, with the partial pressure of water ranging from 10−10 to 10 Torr. The resultant films were then compared to the equivalent thicknesses of thermal and native oxide films. In this way, we obtain unprecedented insight into the essential chemical structures formed during the initial oxidation and subsequent layer growth of these technologically relevant films.
Journal of Applied Physics | 2001
Alain Estève; Yves J. Chabal; Krishnan Raghavachari; Marcus K. Weldon; K. T. Queeney; M. Djafari Rouhani
An atomic scale model of thermal oxidation of Si(100) has been developed based on a kinetic Monte Carlo approach. This method makes it possible to analyze the effects of elementary mechanistic steps of oxidation on macroscopic surfaces. The initial thermal decomposition of chemisorbed hydroxyl groups resulting from water adsorption on Si(100)-(2×1) is investigated by utilizing extensive IR data and ab initio calculations.
Tribology Letters | 1999
James D. Batteas; Xuhui Quan; Marcus K. Weldon
The adhesion and wear of colloidal silica nanoparticles (50 nm diameter) dispersed in a film have been directly studied using atomic force microscopy (AFM) under aqueous solution conditions. The adhesion between surface‐bound silica particles and the AFM tip is found to peak in strength between pH 4 and 5. Using the JKR contact mechanics model, the energy for a single Si–OH/Si–OH interaction was estimated to be 0.4 ± 0.1 kcal/mol. Tribochemical wear of the silica particles, and their displacement from the film, is enhanced at high pH due to the increased facility of silica dissolution and the concomitant increase in attendant inter‐particle repulsion.