Baylor > TSAPS Fall Meeting > FIAP Information > Current Abstracts
Current FIAP Abstracts
- Energetic Fluorocarbon Ion Bombardment on Fluorocarbon Passivated SiO2
S. Rauf, P. Stout, P. Ventzek, V. Smirnov, A. Stengatch, K. Ganulin, and V. Pavlovsky Freescale Semiconductor Inc.
A molecular dynamics model is used to investigate the impact of energetic (50-1000 eV) fluorocarbon ions (CF+, CF2+, CF3+) on fluorocarbon passivated SiO2 surface. In the model, pseudo-potentials for two and three body interactions have either been obtained from previous studies on relevant systems or computed using ab-initio techniques. The computational lattice is prepared by starting with alpha-Quartz and growing a fluorocarbon passivation film using 30-50 eV fluorocarbon ions. The top layers are amorphized in the process as well. Passivation film thickness is in the range 5-20 +. These passivated surfaces are bombarded by energetic fluorocarbons ions with different energies and angles, and effluents are analyzed to understand ion etching characteristics. Analyzed results include aggregate and individual sputter yields, mean energy of sputtered clusters, and energy and angular distribution of sputtered clusters. Reported results provide new insights about fragmentation of incident ions within the material, energy deposition in the top layers, and formation of sputtered clusters.
- Exploring the Macro World and Micro World of a Silver Spoon
K. Kastro M. Hamed
In a study intended to explore students' understanding of surface phenomena and how students analyze familiar phenomena that they had little or no formal instruction about, one group of questions focused on what happens to a metallic spoon placed in an oven that is totally empty otherwise. The students were interviewed, and their answers were audio taped and analyzed qualitatively. In this talk, I would like to share with the audience the main themes that emerged from the analysis. Also, I plan to present the implications to physics teaching and learning, particularly in thermodynamics and in surface science.
John Ellis, V. E. Mayes, D. V. Nanopoulos,Texas A&M University
Cryptons are metastable bound states of fractionally-charged particlesthat arise generically in the hidden sectors of models derived fromheterotic string. We study their properties and decay modes in a specificflipped SU(5) model with long-lived four-particle spin-zero bound statescalled tetrons. We show that the neutral tetrons are metastable, andexhibit the tenth-order non-renormalizable superpotentialoperators responsible for their dominant decays. By analogy with QCD, weexpect charged tetrons to be somewhat heavier, and to decay relativelyrapidly via lower-order interactions that we also exhibit. The expectedmasses and lifetimes of the neutral tetrons make them good candidates forcold dark matter (CDM), and a potential source of the ultra-high energycosmic rays (UHECRs) which have been observed, whereas the charged tetronswould have decayed in the early Universe.
- Non Preferential Surfaces for Self-assembly of Patterned Copolymers
William Gibson, Jeremy Jarl, Eric Botello, Elizabeth Covington, David Donnelly, Heather Galloway, Phillip Hartnet, Deborah Koeck, David Moore Department of Physics. GaryBeall,ChadBooth, Patrick Cassidy, Suresh Murugesan Department of Chemistry and Biochemistry, Texas State University-San Marcos
We are investigating the deposition of ordered films of diblock copolymers onto semiconductor substrates. These surfaces require a non-preferential surface to allow the ordering of the diblock material. The literature available on the deposition of random copolymers (RCP) of polystyrene and polymethyl methacrylate on silicon describes anneal times ranging from one to seven days. We are interested in closer study of the necessary anneal time and of extending the use of RCP onto an amorphous SiC layer deposited on silicon. We found a hydroxyl group is necessary for a non preferential surface when applying a RCP to SiC. We found a minimum anneal time and look at the significance of quenching to room temperature on the bonding/surface conditions (RMS roughness and defect frequencies) of the RCP. We compared different rinse methods post anneal of the RCP to prepare the surface for application of self-assembling polymer structures. The analysis of random copolymer application is accomplished using Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Force Microscopy (AFM). Additionally we have successful self-assembly of P(S-b-MMA) with a 51:49 ratio on SiC.
- Reactive Ion Etching of SiC and SiCN using Tetrafluoroethane and Oxygen
McDonald, James S.; Martinez, Casey; Radican, Kevin; Botello, Eric; Koeck, Deborah C.; Donnelly, David; Geerts, Wilhelmus; Spencer, Gregory; Galloway, Heather C. Texas State University-San Marcos
The ability to pattern thin films of SiC and SiCN is a criticalstep in the fabrication of new high-temperature, high-speed, and high-powerelectronic devices. The etch rate as a function of oxygen concentration wasinvestigated in the RF magnetron plasma etching of SiC withtetrafluoroethane gas. The strong bond nature of these semiconductormaterials requires plasma-based etching in order to take advantage of therelative anisotropy that is required at the sub-8m scale. Reactive ionetching with fluorinated plasmas has been developed to the point where it iswidely employed for both research and commercial product fabrication. Themost common and in many cases the most powerful fluorinated gases for plasmaetching have very high global warming potentials. Fluorinated hydrocarbons(HFC#039s) on-the-other-hand have very high fluorine content as well as beingan environmentally benign replacement for previously used environmentallyharmful gases. It is also a nontoxic, ozone friendly gas with a shortatmospheric lifetime. The role of oxygen in the etching process will bediscussed and this etching process will be reported.
- Texas Tech University's Master of Science Program with Semiconductor Industry Internships
Charles W. Myles, Mark W. Holtz, and Roger L. Lichti , Texas Tech University, Lubbock, Texas.
This presentation gives an overview of the MS in Applied Physics Program atTexasTechUniversity, which incorporates internships in the semiconductor industry as part of its curriculum. It is designed as a Professional MS Program (that is, as a terminal degree program for students who do not want a PhD). The intended audience is undergraduate or graduate students who might be interested in coming to Texas Tech in this program and physics faculty and industrial physicists who might be interested in learning about it. The motivations for starting this program, an overview of the curriculum, and other program details will be discussed. More details about this program may be found at .
- Computational Materials for CMOS Technology
Alex Demkov, Freescale Semiconductor, Inc., Freescale Semiconductor, Inc. 3501 Ed Bluestein Blvd, MD: K10, Austin, TX 78721, firstname.lastname@example.org
The present state of the semiconductor industry presents a golden opportunity for increased engagement by physicists. By shrinking the sizes of devices, semiconductor manufacturers have been successful in decreasing for each technology node the cost per functional throughput per unit area or unit volume. However, the traditional scaling is likely to stop before the end of this decade. On the other hand the reduced size of the system makes it more amenable to computer modeling. I will discuss how computational materials science is used to aid developing novel gate dielectrics, SiGe devices, Nano transistors and Silicon on Insulator technology.
- The Effect of Stacking and Redox State on Optical Absorption Spectra of Melanins- a comparison of theoretical and experimental results.
Klaus B. Stark,James M. Gallas, Gerry W. Zajac ,Joseph T. Golab, Shirley Gidanian, Theresa McIntire and Patrick J. Farmer
Spectroscopic simulations of a leading structural model for melanin, the pigment responsible for coloration and photo protection in humans and animals, were done. In direct continuation of an earlier study (Stark et al. J. Phys. Chem., B 2003, 307, 361) on possible monomer and dimer subunits of eumelanin, we have performed Density Functional Theory (DFT) calculations on a recent structural model for eumelanin based upon higher oligomers of neutral 5,6-indolequinone. This paper further reports on our semi-empirical spectroscopic simulations for the higher oligomer (tetramers through hexamers) energy-minimized structures. A linear combination of the oligomeric spectra reproduces several features of the experimental spectrum. The effect of aggregation and oxidation on the optical absorption of eumelanin oligomeric sheets is investigated by applying quantum mechanics and atomistic simulation studies to a simplified eumelanin structural models that includes 1 to 4 sheets of hexameric oligomer sheets. The oligomeric hypothesis is supported by AFM characterizations of synthetic eumelanins, formed by auto-oxidation or electrochemical oxidation of dihydroxyindole (DHI). Comparison of calculated absorption spectra to experimental spectra demonstrates a red shift in absorption with oxidation and stacking of the eumelanin, and validates the theoretical results.
- Dynamics of Defects and Dopants in Complex Systems:
Taras A. Kirichenko, Decai Yu, Gyeong S. Hwang and Sanjay K. Banerjee
Fabrication of forthcoming nanometer scale electronic devices faces many difficulties including formation of extremely shallow and highly doped junctions. At present, ultra-low-energy ion implantation followed by high-temperature thermal annealing is most widely used to fabricate such ultra-shallow junctions. In the process, a great challenge lies in achieving precise control of redistribution and electrical activation of dopant impurities. Native defects (such as vacancies and interstitials) generated during implantation are known to be mainly responsible for the TED and also influence significantly the electrical activation/deactivation. Defect-dopant dynamics is rather well understood in crystalline Si and SiO2. However, little is known about their diffusion and annihilation (or precipitation) at the surfaces and interfaces, despite its growing importance in determining junction profiles as device dimensions get smaller. We will present our density functional theory calculation results on the atomic and electronic structure and dynamical behavior of native defects and dopant-defect complexes in disordered/strained Si and oxide systems, such as i) clean and absorbent-modified Si(100) surface and subsurface layers, ii) amorphous-crystalline Si interfaces and iii) amorphous SiO2/Si interfaces. The fundamental understanding and data is essential in developing a comprehensive kinetic model for junction formation, which would contribute greatly in improving current process technologies.
- Comparison of ALD and MOCVD deposition processes for deposition of Hafnium Silicate
Siddarth A. Krishnan, Paul D. Kirsch, Byoung Hun Lee, Jeff Peterson, Hong Jyh Li, Jim Gutt
Atomic Layer Deposition (ALD) and Metal Organic Chemical Vapor are among the forerunners in the various deposition techniques that are being used to deposit alternative gate dielectric materials. The two techniques were studied with respect to electrical characteristics for depositing Hafnium Silicate films. The ALD films had three different deposition temperatures, along with variable Ozone precursor concentration and flow times. Temperature was found to be the most dominant factor affecting EOT, Jg and flatband voltage (Higher deposition temperature yielded higher EOTs). Different PDA's (N2, NH3 and NO) were performed at varying temperatures on the ALD films. Higher PDA temperatures increased the EOT for all PDA's, while the NH3 PDA's yielded the lowest EOTs. The Nitrogen PDA had the best thermal stability. EOT of 8.7-9.0+ and mobility of 63% of universal SiO2 at 1MV/cm were obtained for both HfSiO (1:1) and HfSiO (5:1). In the case of MOCVD also, the deposition temperature was the dominant factor (higher temperature yielded lower EOT). The best electrical characteristics were obtained with a deposition temperature of 615 C and a PDA at 800 C (EOT of 8.5+ and high-field mobility of 65% universal at 1MV/cm obtained)