Fikru Adamu-Lema

Research Interest

Device Modelling and Simulation


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My main research interest comprehends, among other things, development of oxide reliability model, and statistical simulation of nano-scale conventional CMOS and non-conventional like silicon on insulator (SOI) and FinFETs. Looking back about 3 decades, the advantages of device miniaturization (mainly cost and performance) outweighs the challenges to fabricate them (for example technological challenges).  The end of this successful run of aggressive scaling of CMOS devices is fast approaching its limitation, to a point where it cannot continue in its present form or shape. Based on the current research work in Device Modelling group at University of Glasgow and other research groups, of all the challenges that hinders the progress of of scaling is variability of device parameters. It has severe consequences on device operations and on its reliability.  The variability, which we investigate are random discrete dopant, line edge roughness and the metal grain and granularity effects on carrier transport and device performance and advanced circuit functionality.



Recent grants worked on

2012 - 

 

 


 

2011 - 

Statistical Design and Verification of Analogue Systems (StatDes)

StatDesLogo.pngIn addition to my research activity in the area of Oxide Reliability in nano-scale semiconductor devices, I am working as a Project Coordinator of StatDes. It is a synergy between academic research community (Universities of Glasgow and Edinburgh) and industry (GSS, Wolfson microelectronics, and IBM) with objectives of enabling designers by delivering a better analogue, mixed signal, and Digital electronics designing tools, delivering improved design practice and solutions that will result in a better system on chip (SoC) design and delivering well trained analogue design experts.

Oxide Reliability of NANO-SCALE transistors:

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My current project is focused on statistical investigation of oxide reliability wear-out mechanisms and performance degradation of nano-scale transistors.  In particular, the project gives emphasis to research on instabilities due to bias temperature stress  (P/NBTI), hot carrier degradation (HCD) and the investigation of time dependent degradation of dielectric materials breakdown (TDDB), which adversely affects the reliability of CMOS devices. For this purpose, we are developing a 3D-statistical model that applies the principles of Kinetic Monte-Carlo to account the time-evolution of device simulations and the dynamics of trapping and de-trapping mechanisms (transition dynamics). The model will then be integrated into 3D Glasgow Atomistic Simulator to enable as performing a full 3D statistical simulation on different device architectures with various dimensions. 

MORDRED_logo.pngThe research program that I am currently involved with is supported by the MORDRED European collaborative project on modelling of the reliability and degradation of next generation nanoelectronic devices, involving the following industrial and academic research partners (IFX, IMEC, KUL-E, KUL-P, GSS, GU, TUT, TUW, UCL).

Publications

2013

  • F. Adamu-Lema, C. M. C. M. Compagnoni, S. M. Amoroso, N. Castellani, S. Markov, L. Gerrer, A. S. A. S. Spinelli, A. L. A. L. Lacaita and A. Asenov, "Accuracy and issues of the spectroscopic analysis of RTN traps in nanoscale MOSFETs," IEEE Trans. Electron Devices, Vol. 60, No. 2, pp. 833–839, Feb. 2013.
  • S. M. Amoroso, L. Gerrer, S. Markov, F. Adamu-Lema and A. Asenov, "RTN and BTI in Nanoscale MOSFETs: A Comprehensive Statistical Simulation Study," Solid State Electronics, Mar. 2013.
  • X. Wang, F. Adamu-Lema, B. Cheng and A. Asenov, "Geometry, Temperature, and Body Bias Dependence of Statistical Variability in 20-nm Bulk CMOS Technology: A Comprehensive Simulation Analysis," IEEE Trans. Electron Devices, Vol. 60, No. 5, pp. 1547–1554, May 2013.

2012

  • F. Adamu-Lema, S. M. Amoroso, S. Markov, L. Gerrer and A. Asenov, "A Unified Computational Scheme for 3D Statistical Simulation of Reliability Degradation of Nanoscale MOSFETs," 17th International Conference on Simulation of Semiconductor Processes and Devices (SISPAD): Sept. 5-7, 2012.
  • S. M. Amoroso, L. Gerrer, S. Markov, F. Adamu-Lema and A. Asenov, "Comprehensive Statistical Comparison of RTN and BTI in Deeply Scaled MOSFETs by means of 3D ‘Atomistic’ Simulation," 42nd European Solid-State Device Research Conference (ESSDERC): Sept. 17-21, 2012.
  • S. M. Amoroso, F. Adamu-Lema, S. Markov, L. Gerrer and A. Asenov, "3D Dynamic RTN Simulation of a 25nm MOSFET: The Importance of Variability in Reliability Evaluation of Decananometer Devices," 15th International Workshop on Computational Electronics (IWCE): 2012.
  • L. Gerrer, S. Markov, S. M. Amoroso, F. Adamu-Lema and A. Asenov, "Impact of random dopant fluctuations on trap-assisted tunnelling in nanoscale MOSFETs," Journal of Microelectronics Reliability, July 2012.
  • S. Markov, L. Gerrer, S. M. Amoroso, F. Adamu-Lema and A. Asenov, "Time Domain Simulation of Statistical Variability and Oxide Degradation Including Trapping/detrapping Dynamics," 17th International Conference on Simulation of Semiconductor Processes and Devices (SISPAD): Sept. 5-7, 2012.

2007

  • K. Samsudin, F. Adamu-Lema, A. R. Brown, S. Roy and A. Asenov, "Combined sources of intrinsic parameter fluctuations in sub-25 nm generation UTB-SOI MOSFETs: A statistical simulation study," Solid-State Electronics, Vol. 51, No. 4, pp. 611–616, 2007.

2006

  • G. Roy, A. R. Brown, F. Adamu-Lema, S. Roy and A. Asenov, "Simulation study of individual and combined sources of intrinsic parameter fluctuations in conventional nano-MOSFETs," IEEE Transactions on Electron Devices, Vol. 53, No. 12, pp. 3063–3070, 2006.
  • G. Roy, A. R. Brown, F. Adamu-Lema, S. Roy and A. Asenov, "Intrinsic Parameter Fluctuations in Conventional MOSFETs until end of the ITRS," Journal of Physics Conferences Series, Vol. 38, pp. 188–191, 2006.
  • K. Samsudin, F. Adamu-Lema, A. R. Brown, S. Roy and A. Asenov, "Intrinsic parameter fluctuations in sub-10nm generation UTB SOI MOSFETs," ser. 7 th European Workshop on ULtimate Integration of Silicon , ULIS 2006, pp. 93–96.

2005

  • B. Cheng, S. Roy, G. Roy, F. Adamu-Lema and A. Asenov, "Impact of intrinsic parameter fluctuations in decanano MOSFETs on yield and functionality of SRAM cells," Solid-State Electronics, Vol. 49, No. 5, pp. 740–746, 2005.
  • G. Roy, F. Adamu-Lema, A. R. Brown, S. Roy and A. Asenov, "Simulation of combined sources of intrinsic parameter fluctuations in 'real' 35nm MOSFET," ser. European Solid-State Device Research Conference 2005 - ESSDERC2005, Grenoble, France,
  • G. Roy, F. Adamu-Lema, A. R. Brown, S. Roy and A. Asenov, "Intrinsic parameter fluctuations in conventional MOSFETs until the end of the ITRS," ser. New Phenomena in Mesoscopic Structures - 7 (NPMS) and the fifth in the series of Surfaces and Interfaces of Mesoscopic Devices (SIMD), NPMS-7/ SIMD-5,
  • L. Yang, J. R. Watling, F. Adamu-Lema and A. Asenov, "Simulations of Sub-100 nm Strained Si MOSFETs with High-k Gate Stacks," Computational Electronics, Vol. 3, pp. 171–176, 2005.

2004

  • F. Adamu-Lema, S. Roy, A. R. Brown, A. Asenov and G. Roy, "Intrinsic parameter fluctuations in conventional MOSFETs at the scaling limit: a statistical study," in Proc. 10th International Workshop on Computational Electronics (IWCE), West Lafayette, IN, USA, Oct. 24-27, 2004, pp. 44–45.
  • F. Adamu-Lema, G. Roy, A. R. Brown, A. Asenov and S. Roy, "Intrinsic parameter fluctuations in conventional MOSFETs at the scaling limit:a statistical study," J. Computational Electronics, Vol. 3, pp. 203–206, 2004.
  • B. Cheng, S. Roy and F. Adamu-Lema, "Impact of intrinsic parameter fluctuations in decanano MOSFETs on yield and functionality of SRAM cells," ser. 5th European Workshop on Ultimate Integration of Silicon - ULIS04, pp. 23–26.
  • L. Yang, J. R. Watling, F. Adamu-Lema, A. Asenov and J. R. Barker, "Simulations of sub-100nm strained Si MOSFETs with high k gate stacks," ser. International workshop on Computational Electronics, IWCE-10, West Lafeyette, USA,
  • L. Yang, J. R. Watling, F. Adamu-Lema, A. Asenov and J. R. Barker, "Scaling study of Si and strained Si n-MOSFETs with different high-k gate stacks," in Proc. 2004 International Electron Device Meeting (IEDM), Dec.

2003

  • A. R. Brown, F. Adamu-Lema and A. Asenov, "Intrinsic parameter fluctuations in nanometer scale thin body SOI devices introduced by interface roughness," 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), Maui, HI, USA, Nov. 30-Dec. 5, 2003, pp. 32–33.
  • A. R. Brown, F. Adamu-Lema and A. Asenov, "Intrinsic parameter fluctuations in UTB MOSFETs induced by body thickness variations," in Proc. Silicon Nanoelectronics Workshop, Kyoto, Japan, June 8-9, 2003,
  • A. R. Brown, F. Adamu-Lema and A. Asenov, "Intrinsic Parameter Fluctuations in Nanometre Scale Thin-body SOI Devices Introduced by Interface Roughness," Superlattices and Microstructures, Vol. 34, No. 3-6, pp. 283–291, 2003.

2002

  • A. Asenov, M. Jaraiz, S. Roy, G. Roy, F. Adamu-Lema, A. R. Brown, V. Moroz and R. Gafiteanu, "Integrated atomistic process and device simulation of decananometre MOSFETs," in Proc. Simulation of Semiconductor Processes and Devices, Kobe, Japan, Sept. 4-6, 2002, pp. 87–90.