Second project period 10/2010 - 03/2015

Project No. Project Name Responsible
G3 Multiscale modeling and simulation of atomic layer deposition and calculation of electronic properties of nanoscale devices Prof. Dr. Thomas GESSNER
Dr. Reinhard STREITER

Main Objectives

Description

Models for novel nano technology processes and devices
Nanodevices cannot be described by classical treatments based on conventional continuum models any more. Novel device design methods (process and characteristics) based on quantum mechanics must be used. Atomic layer deposition (ALD) is a key process for making highly uniform and conformal thin films. For nanoscale devices especially, each of the layers should be as thin and as perfect as possible. In order to realize thin layers with excellent step coverage in a reasonable process time, ALD models have to be designed and respective parameters have to be found [G3-1],[G3-2] . Based on the expertise in multiscale deposition modeling and simulation of (MO)CVD, PVD, and epitaxial processes using continuum, Monte Carlo, and Molecular Dynamics, this project is dedicated to improve and extend the competence also for nanoscaled deposition [3]. The goal of this project will be to find out ALD deposition rate pathways for different materials and the respective activation energies. Simulation models must be available on all scales for the species transport at reactor, feature and atomic scale. Additionally, chemistry modeling of the reaction step and the postreaction purge steps must be performed. The result is the atomic structure of device surfaces which can be used for succeeding atomic scale device simulation.

Simulations of ALD processes will be performed using the software package "Materials Studio" offered by Accelrys. The package contains various modules which cover most of the state-of-the-art quantum chemical and physical simulation concepts (e. g., Monte Carlo, Molecular Dynamics, Density Functional Theory methods). Using this, we will be capable to simulate and predict many details of the ALD processes such as precursor geometry on surfaces, potential binding sites, reaction pathways as well as properties of the final metal films by using one single user interface. In addition, extensive visualization of simulation results and usage of our distributed computing server infrastructure is offered by the package.

Calculation of electronic properties of nanoscale devices
The computation of quantities of nanoscaled devices which can be compared to experiments is the novel challenge of the nanodevice area. Different geometries can be the focus of the computational investigations. Highest importance for the understanding of device behavior is the description of nanocontacts between different materials at the atomic scale. Further, the functionalization of surfaces can only be understood by using computational experiments. Comparisons with experiments are based on current–voltage characteristics in two-probe systems under finite bias. Large-scale systems under consideration are nanowires, multi- as well as single-wall nanotubes and complex interface structures. This part of the project is the continuation of results of project G2 of the first period (electrical behavior) of point contacts and nanowires, resistivity/performance of advanced structures for interconnect systems, software evaluation). The modeling focus is on the continuation and extension of nanowire simulation [G3-4]-[G3-6]. Therefore, the geometry definition and especially its optimization must be performed. Calculation of bias-induced forces, of the electronic structure and transport have to be realized using carefully selected software tools which must be extended for special applications [G3-7]-[G3-10]. Of interest are the influence of surface coverage on electronic transport, the influence of defects and the interaction between carbon nanotubes. Finally, methods must be worked out for the statistical treatment of real structures.

References

[G3-1] D.R. Burgess, Jr., J.E. Maslar, W.S. Hurst, E.F. Moore, W.A. Kimes, and N.V. Nguyen, "Atomic Layer Deposition: Process Models and Metrologies", Characterization and Metrology for ULSI Technology: 2005 International Conference, edited by D. G. Seiler et al., AIP Conference Proceedings 788, Melville, NY: American Institute of Physics, 2005, pp. 141-146
[G3-2] J.E. Maslar, W.S. Hurst, D.R. Burgess, Jr., W.A. Kimes, and N.V. Nguyen, “In Situ Characterization Of Gas-Phase Species Present During Hafnium Oxide Atomic Layer Deposition”, Electrochemical Society Transactions, 2006
[G3-3] Belsky,P.; Streiter,R.; Wolf,H.; Gessner,T.: Application of Molecular Dynamics to the Simulation of IPVD. Advanced Metallization Conference 2004, San Diego CA, U.S.A., 2004 Oct 19-21; MRS Conf. Proc. AMC XX, Material Research Society, Warrendale PA (2005), pp 787-792 (ISBN 1-55899-814-4 / ISSN 1048-0854)
[G3-4] S. Mohammadzadeh, D. Pouladsaz, R. Streiter, T. Gessner, "Quantum conductance of copper nanowires", DPG Spring Meeting, Berlin (Germany), 25-29 February 2008.
[G3-5] S. Mohammadzadeh, D. Pouladsaz, R. Streiter, T. Gessner, "Electronic transport properties in copper nanowire", MAM 2008 - Materials for Advanced Metallization Conference, Dresden (Germany), 2-5 March 2008; published in Microelectron. Eng. 85, pp. 1992-1994 (2008).
[G3-6] S. Mohammadzadeh, D. Pouladsaz, R. Streiter, T. Gessner, "Theoretical study of electron transfer through copper and gold nanowires", Nanoelectronics Day, Aachen (Germany), 13-16 May 2008
[G3-7] S. Mohammadzadeh, D. Pouladsaz, R. Streiter, T. Gessner, "Theoretical study of electronic transfer through gold and copper quantum point contacts", AMC - Advanced Metallization Conference, San Diego, California (USA), 23-25 September 2008.
[G3-8] D. Pouladsaz, S. Mohammadzadeh, T. Gessner, M. Schreiber, R. Streiter, "Theoretical study of electron transfer through polyacetylene nanowires in different contact structures", DPG Spring Meeting, Berlin (Germany), 25-29 February 2008.
[G3-9] Nanotechnology conference Genoa, S. Mohammadzadeh
[G3-10] Nanotechnology conference Hong Kong, S. Mohammadzadeh