Craig Alexander

Area of work

3D Monte Carlo simulator development

Electron density within a 35nm nMOSFET with multiple sources of variability

The Glasgow 3D Monte Carlo simulator is a generalised device simulator developed in tandem with the Glasgow 'atomistic' device simulator, GARAND. It has been designed specifically for the investigation of intrinsic statistical device variability where variation in carrier transport, in addition to electrostatic modulation, is an important consideration. It is complimentary to the GARAND simulator, capable of simulation of the same device structures with the same sources of statistical variability; random discrete dopants (RDD), line edge roughness (LER), line width roughness (LWR), oxide thickness variations (OTV), poly-silicon granularity (PSG) and metal gate granularity (MGG). The general design of the simulator makes simulation of electron and hole transport within Silicon, Germanium and within III-V materials possible in combination with the above sources of statistical variability.

The 3D Monte Carlo simulator is uniquely capable of treating scattering processes such as ionised impurity and surface roughness scattering directly, given the 3D resolved device potential, instead of using bulk scattering rate models as typically applied. This approach is the most accurate for treating the position dependent scattering that gives rise to transport variation between microscopically unique devices. This technique has also been applied to transport variation associated with position dependent scattering from PSG and MGG. 3D quantum corrections via the density gradient approach are also included in defining the device potential, recoveing quantum confinement effects as well as efficiently resolving the scattering potential associated with discrete sources.

Development is conducted as part of a team, including

Dr Craig Riddet
Dr Ewan Towie
Dr Brahim Benbakti

Recent grants worked on

2010 -

My current project

 
2005 - 2010

EPSRC Platform grant

The flexibility of the platform grant allowed sustained long-term development of the 3D Monte Carlo device simulator. The core design of the simulator along with incorporation of quantum confinement effects and multiple sources of variability was completed during this time.

Publications

2011

  • C. Riddet, C. L. Alexander, A. R. Brown, S. Roy and A. Asenov, "Simulation of "Ab Initio" Quantum Confinement Scattering in UTB MOSFETs Using Three-Dimensional Ensemble Monte Carlo," IEEE Transactions on Electron Devices, Vol. 58, No. 3, pp. 600–608, Mar. 2011.

2010

  • C. L. Alexander and A. Asenov, Eds., 'ab initio' Surface Roughness Scattering in 3D Monte Carlo Transport Simulations, 2010,
  • A. R. Brown, J. R. Watling, G. Roy, C. Riddet, C. L. Alexander, U. Kovac, A. Martinez and A. Asenov, "Use of density gradient quantum corrections in the simulation of statistical variability in MOSFETs," Journal of Computational Electronics, Vol. 9, No. 3-4, pp. 187–196, 2010.
  • U. Kovac, C. L. Alexander, G. Roy, C. Riddet, B. Cheng and A. Asenov, "Hierarchical Simulation of Statistical Variability: From 3-D MC with ‘ab initio’ Ionized Impurity Scattering to Statistical Compact Models," IEEE Transactions on Electron Devices, 2010.

2009

  • A. Asenov, A. R. Brown, G. Roy, B. Cheng, C. L. Alexander, C. Riddet, U. Kovac, A. Martinez, N. Seoane and S. Roy, "Simulation of statistical variability in nano-CMOS transistors using drift-diffusion, Monte Carlo and non-equilibrium Green’s function techniques," Journal of Computational Electronics, Vol. 8, No. 3-4, pp. 349–373, 2009.
  • P. Palestri, C. L. Alexander, A. Asenov, V. Aubry-Fortuna, G. Baccarani, A. Bournel, M. Braccioli, B. Cheng, P. Dolfus, A. Esposito, D. Esseni, C. Fenouillet-Beranger, C. Fiegna, G. Fiori, A. Ghetti, G. Iannaccone, A. Martinez, B. Majkusiak, S. Monfray, V. Peikert, S. Reggiani, C. Riddet, J. Saint-Martin, E. Sangiorgi, A. Schenk, L. Selmi, L. Silvestri, P. Toniutti and J. Walczak, "A comparison of advanced transport models for the computation of the drain current in nanoscale nMOSFETs," Solid-State Electronics, Vol. 53, No. 12, pp. 1293–1302, Dec. 2009.

2008

  • C. L. Alexander, G. Roy and A. Asenov, "Random-Dopant-Induced Drain Current Variation in Nano-MOSFETs: A Three-Dimensional Self-Consistent Monte Carlo Simulation Study Using "ab initio" Ionized Impurity Scattering," IEEE Trans. Electron Devices, Vol. 55, No. 11, pp. 3251–3258, Nov. 2008.
  • A. Asenov, S. Roy, A. R. Brown, G. Roy, C. L. Alexander, C. Riddet, C. Millar, B. Cheng, A. Martinez, N. Seoane, D. Reid, M. Faiz. Bukhori, X. Wang and U. Kovac, "Advanced simulation of statistical variability and reliability in nano CMOS transistors," in Proc. IEDM, USA, Dec. 2008, p. 421.

2007

  • C. Riddet, A. R. Brown, C. L. Alexander, J. R. Watling, S. Roy and A. Asenov, "3-D Monte Carlo simulation of the impact of quantum confinement scattering on the magnitude of current fluctuations in double gate MOSFETs," IEEE Transactions on Nanotechnology, Vol. 6, No. 1, pp. 48–55, 2007.

2006

  • C. L. Alexander, G. Roy and A. Asenov, "Increased intrinsic parameter fluctuations through ab initio Monte Carlo simulations in nano-scaled MOSFETs," in Proc. International Electron Devices Meeting 2006, ser. International Electron Devices Meeting 2006, IEDM, San Fransisco, CA, USA, Dec. 11-13, 2006,
  • A. Asenov, A. R. Brown, G. Roy, C. L. Alexander and A. Martinez, "Simulation of Atomic Scale Effects and Fluctuations in nano-scale CMOS," in Proc. Solid-State Devices and Materials (SSDM), Yokohama, Japan, Sept. 12-15, 2006, pp. 358–359.
  • A. Asenov, A. R. Brown, B. Cheng, J. R. Watling, G. Roy and C. L. Alexander, "Simulation of nano-CMOS devices: from atoms to architecture," in Nanotechnology for Electronic Materials and Devices, A. Korkin, J. Labanowski, E. Gusev and S. Luryi, Eds. New York: Springer, 2006, pp. 257–303.
  • C. Riddet, A. R. Brown, C. L. Alexander, S. Roy and A. Asenov, "Efficient density gradient quantum corrections for 3D Monte Carlo simulations," ser. International Conference on Simulation of Semiconductor Processes and Devices, SISPAD 2006, California,USA,

2005

  • C. L. Alexander, A. R. Brown, J. R. Watling and A. Asenov, "Impact of single charge trapping in nano-MOSFETs - Electrostatics versus transport effects," IEEE Transactions on Nanotechnology, Vol. 4, No. 3, pp. 339–344, 2005.
  • C. L. Alexander, A. R. Brown, J. R. Watling and A. Asenov, "Impact of scattering in 'atomistic' device simulations," Solid-State Electronics, Vol. 49, No. 5, pp. 733–739, 2005.
  • C. Riddet, A. R. Brown, C. L. Alexander, J. R. Watling, S. Roy and A. Asenov, "Impact of quantum confinement scattering on the magnitude of current fluctuations in double gate MOSFETs," ser. Silicon Nanoelectronics Workshop 2005,
  • J. R. Watling, A. R. Brown, C. L. Alexander, G. Ferrari, J. R. Barker, G. Bersuker, P. Zeitzoff and A. Asenov, "Electrostatic and transport variations in nano CMOS devices due to variations in high-k oxides," ser. 2nd International Workshop on Advanced Gate Stack Technology, Texas, USA,

2004

  • C. L. Alexander, J. R. Watling and A. Asenov, "Numerical carrier heating when implementing (PM)-M-3 to study small volume variations," Semiconductor Science and Technology, Vol. 19, No. 4, p. S139–S141, 2004.
  • C. L. Alexander, A. R. Brown, J. R. Watling and A. Asenov, "Impact of scattering on random dopant induced current fluctuations in decanano MOSFETs," in Proc. SISPAD, ser. Simulation of Semiconductor Processes and Devices, pp. 223–226.
  • C. L. Alexander, A. R. Brown, J. R. Watling and A. Asenov, "Impact scattering in 'atomistic' device simulation," in Proc. Ultimate Intigration of Silicon, ser. 5th European Workshop on Ultimate Integration of Silicon - ULIS04,
  • C. L. Alexander, A. R. Brown, J. R. Watling and A. Asenov, "Impact of single charge trapping in nano-MOSFETs," in Proc. Silicon Nanoelectronics Workshop, ser. IEEE 2004 Silicon Nanoelectronics Workshop, Honolulu,
  • C. L. Alexander, J. R. Watling and A. Asenov, "Small volume mobility variations due to lonised impurity scattering," Semiconductor Science and Technology, Vol. 10S, pp. 139–141, 2004.
  • C. L. Alexander, A. R. Brown, J. R. Watling and A. Asenov, "Impact of scattering in 'atomistic' device simulation," in Proc. Proc. ULIS 2004, Leuven Belgium, pp. 89–92.
  • A. Asenov, G. Roy, C. L. Alexander, A. R. Brown, J. R. Watling and S. Roy, "Quantum mechanical and transport aspects of resolving discrete charges in nano-CMOS device simulation," in Proc. 4th IEEE Conference on Nanotechnology (IEEE Nano), Munich, Germany, Aug. 17-19, 2004, pp. 334–336.
  • C. Riddet, A. R. Brown, C. L. Alexander, J. R. Watling, S. Roy and A. Asenov, "Scattering from body thickness fluctuations in double gate MOSFETs. An ab initio Monte Carlo simulation study," ser. International workshop on Computational Electronics, IWCE-10, West Lafayette, USA, pp. 194–195.
  • C. Riddet, A. R. Brown, C. L. Alexander, J. R. Watling, S. Roy and A. Asenov, "Scattering From Body Thickness Fluctuations in Double Gate MOSFETs. An ab initio Monte Carlo Study." J. Comp. Elec, Vol. 3, pp. 341–345, 2004.

2003

  • C. L. Alexander, J. R. Watling and A. Asenov, "Artificial carrier heating due to the introduction of ab-initio Coulomb scattering in Monte Carlo simulations," in Proc. Sixth International Conference on New Phenomena in Mesoscopic Systems, and Fourth International Conference on Surfaces and Interfaces of Mesoscopic Devices (NPMS-6/SIMD-4),
  • C. L. Alexander, J. R. Watling and A. Asenov, "Small volume mobility variations due to ionised impurity scattering," in Proc. Internation Conference on Nonequilibrium Dynamics in Semiconductors, ser. 13th International Conference on Nonequilibrium Carrier Dynamics - HCIS 13,
  • C. L. Alexander, J. R. Watling and A. Asenov, "Mobility variations in ultra-small devices due to discrete charges." J. Computational Electronics, Vol. 2, pp. 285–289, 2003.
  • C. L. Alexander, A. R. Brown, J. R. Watling and A. Asenov, "Artificial carrier heating due to the introduction of ab-initio Coulomb scattering in Monte Carlo simulations." Superlattices and Microstructures, Vol. 34, No. 3-6, pp. 319–326, 2003.
  • C. L. Alexander, J. R. Watling and A. Asenov, "Mobility variations in ultra-small devices due to discrete charges," in Proc. Extended Abstracts IWCE-9, Rome 2003,