1st Edition
Technology Computer Aided Design Simulation for VLSI MOSFET
Responding to recent developments and a growing VLSI circuit manufacturing market, Technology Computer Aided Design: Simulation for VLSI MOSFET examines advanced MOSFET processes and devices through TCAD numerical simulations. The book provides a balanced summary of TCAD and MOSFET basic concepts, equations, physics, and new technologies related to TCAD and MOSFET. A firm grasp of these concepts allows for the design of better models, thus streamlining the design process, saving time and money. This book places emphasis on the importance of modeling and simulations of VLSI MOS transistors and TCAD software. Providing background concepts involved in the TCAD simulation of MOSFET devices, it presents concepts in a simplified manner, frequently using comparisons to everyday-life experiences. The book then explains concepts in depth, with required mathematics and program code. This book also details the classical semiconductor physics for understanding the principle of operations for VLSI MOS transistors, illustrates recent developments in the area of MOSFET and other electronic devices, and analyzes the evolution of the role of modeling and simulation of MOSFET. It also provides exposure to the two most commercially popular TCAD simulation tools Silvaco and Sentaurus.
• Emphasizes the need for TCAD simulation to be included within VLSI design flow for nano-scale integrated circuits
• Introduces the advantages of TCAD simulations for device and process technology characterization
• Presents the fundamental physics and mathematics incorporated in the TCAD tools
• Includes popular commercial TCAD simulation tools (Silvaco and Sentaurus)
• Provides characterization of performances of VLSI MOSFETs through TCAD tools
• Offers familiarization to compact modeling for VLSI circuit simulation
R&D cost and time for electronic product development is drastically reduced by taking advantage of TCAD tools, making it indispensable for modern VLSI device technologies. They provide a means to characterize the MOS transistors and improve the VLSI circuit simulation procedure. The comprehensive information and systematic approach to design, characterization, fabrication, and computation of VLSI MOS transistor through TCAD tools presented in this book provides a thorough foundation for the development of models that simplify the design verification process and make it cost effective.
Introduction to Technology CAD
By Prof. Samar Saha
Technology CAD
A Brief History of TCAD
Motivation for TCAD
TCAD Flow for IC Process and Device Simulation
TCAD Application
Benefit of TCAD in TD Project
Summary
Basic Semiconductor and MOS Physics
By Prof. Swapnadip De
Introduction
Band Formation theory of semi conductor
Concept of effective mass
Basic Semiconductor Equations
Carrier Transport
Carrier recombination and generation
Continuity Equation and solution
Mobility & Scattering
Different Distribution laws
Semiconductor device modeling
Introduction to MOS Transistor
Structure & symbol of MOSFET
Basic Operation of MOSFET
Threshold Voltage of MOSFET
Flat-band voltage: Effect of real surfaces
Expression of Threshold voltage
I-V characteristics of MOSFET
Depletion MOSFET
Trans-conductance
Channel Length Modulation
Substrate Bias Effects
MOS Transistor as a Switch
MOSFET Capacitance
Moore’s law
Introduction to scaling
Constant Field Scaling
Constant Voltage Scaling
Why constant voltage scaling is more useful than constant field scaling?
ITRS roadmap for semiconductors
Different groups of MOSFETs
Short-Channel Effects of MOSFET
Reduction of the effective threshold voltage
Hot Electron effects
Avalanche breakdown and parasitic bipolar action
DIBL (Drain Induced Barrier Lowering)
Velocity saturation in MOSFET
Mobility Degradation
References
Review of Numerical Methods for TCAD
By Kalyan Koley
Introduction
Numerical Solution Methods
Nonlinear Iteration
Convergence criteria for Non-linear Iterations
Initial Guess Requirement
Numerical method implementation
Basic Drift Diffusion Calculations
Drift Diffusion Calculations with Lattice Heating
Energy Balance Calculations
Energy Balance Calculations with Lattice Heating
Setting the Number of Carriers
Important Parameters of the METHOD Statement
Restrictions on the Choice of METHOD
Pisces-II Compatibility
Device Simulation Using ISE-TCAD
By Prof. N.Mohankumar
Introduction
Design Flow
Sentaurus Structure Editor
Sentaurus Device
Tecplot
Inspect
Parameterized Scripting
Sentaurus Workbench
Summary
References
Device Simulation Using Silvaco ATLAS Tool
By Prof. Angsuman Sarkar
Introduction
How the device simulator ATLAS works
ATLAS Inputs and Outputs
Simulation set up
Brief review of electro-physical models employed in ATLAS
Choice of METHOD in ATLAS
Mobility models in ATLAS
Benchmarking of MOSFET simulations
Importance of mesh optimization
Introduction to other tools from Silvaco used in conjunction with ATLAS
Example 1: Bulk n-channel MOSFET simulation
Example 2: SOI MOSFET simulation
Example 3: 0.18µm Bulk nMOS transistor with Halo implant
Example 4: Volume inversion Double-Gate (DG) MOSFET
Summary
References
Study of Deep Submicron VLSI MOSFETs through TCAD
By Prof. Srabanti Pandit
Introduction
Synopsys TCAD Tool Suite
Device Architecture and Simulation Set-up
Short Channel Effects (SCEs)
Drain Induced Barrier Lowering (DIBL)
Mobility Degradation
Drain Characteristics
Velocity saturation
Output Resistance
Inverse Narrow Width Effects (INWEs)
Advanced Device Structures
Conclusion
MOSFET Characterization for VLSI Circuit Simulation
By Prof. Soumya Pandit
Introduction
Device Models for Circuit Simulation
Threshold Voltage Characterization
I-V Characterization
Hot Carrier Effects due to Impact Ionization
Characterization of Gate Dielectric
Capacitance Characterization
Noise Characterization
Statistical Characterization
Classification of Process Variability
Sources of Random Intra-die Process Variations and their Effects
Random Discrete Dopant (RDD)
Line Edge Roughness (LER)
Oxide Thickness Variations (OTV)
Characterization of Process Variability
Design corner approach
Monte Carlo simulation approach
Statistical Corner approach
Simulation Results and Discussion
Statistical Characterization of RDD
Statistical Characterization of LER
Statistical Characterization of OTV
Statistical Characterization of Simultaneous Variations
Summary and Conclusion
Process Simulation of a MOSFET using TSUPREM-4 and MEDICI
By Prof. Atanu Kundu
Introduction
Why silicon?
Initial meshing the wafer
Start material initialization
Defining the initial mesh
N-buried layer
Oxidation and growth the initial oxide
Meshing the wafer for buried layer implantation
Screen oxidation
Buried layer implant
Buried layer drive-in
P-Type epitaxial growth
Pad oxide formation
Gate under channel doping
Gate oxide formation
Gate-poly deposition
Polysilicon gate doping
Gate-poly mask
Creation of n+ source and drain regions
Creation of p+ region
BPSG deposition
BPSG anneal
Contact mask
Metal- Deposition
Metal- Mask
Intermetal dielectric (IMD) deposition
Metal mask
Metal- deposition
Metal- final mask
MOSFET.inp
Mask file named t.tl1
What is MEDICI
Execution of command
Interfacing between TSUPREM4 and MEDICI
Rename electrodes from TSUPREM4 to standard names
Major physical models
Initial guess/Convergence and Solution Methods
Nonlinear system solutions and current-voltage analysis
Post processing and parameter extraction
Drain current vs. drain voltage simulation
Drain current vs. gate voltage simulation
Conclusion
References
Biography
Chandan Kumar Sarkar, is a professor of Electronics and Telecommunication, at Jadavpur University, Calcutta, India and a senior member of IEEE. He received B.Sc. (Hons.) and M.Sc. degrees in physics from Aligarh Muslim University, a Ph.D. degree in Radio Physics from the University of Calcutta, and the D.Phil degree from Oxford University. In 1980 Prof. Sarkar received the British Royal Commission Fellowship to work in Oxford University, worked as a visiting scientist in Max Planck Laboratory, Stuttgart, Germany as well as in Linko Pink University, Sweden. He has published more than 300 research papers for international journals and conferences.
"A unique book combines both device and process simulation so far as I know. It combines principle and practice together and thus is quite suitable for use in classroom or as a self-study reference. It exposes the reader to the realm of device and process simulation, a field being critical important in VLSI but not easily being accessible to the reader due to the lack of comprehensive material available. … Yes, I would like to read this book. Even though I do not teach such a course directly, my yearly VLSI course indeed covers a chapter related to the VLSI manufacturing process and another to device modeling. This book definitely gives much more insight into these. It will give me a thorough understanding of these two important topics. … Because of its uniqueness, this book would be most likely to have a successful market. … A unique book combines both device and process simulation. It is an excellent resource for both the student and professional to these essential topics related to VLSI systems."
––Ming-Bo Lin, Department of Electronic Engineering of National Taiwan University of Science and Technology, Taipei, Taiwan"The materials provided bring up-to-date various aspects of TCAD simulation of VLSI MOSFETs, through providing an overview of TCAD software tools and the physical models included. It highlights the role and importance of TCAD tools in the development and prediction of VLSI MOS transistors’ design, characterization and fabrication. The materials comprise detailed examples with source codes of different types of MOSFETs using Silvaco TCAD device simulation tools, illustrating the key aspects of Silvaco TCAD tools and showing its capability and effectiveness to understand the physical behavior and potential of a device structure. In addition, the book presents a comprehensive overview of compact modeling of MOS transistors for use in VLSI circuit simulation. This approach serves the purpose of the book which is to be tended for students of electrical and electronics engineering disciplines. The book is ideal for students and may also be used as a reference for researchers and professionals working in the area of electronic devices. … I am confident that the materials presented serve the purpose of this book quite well, and provide the target audience with a good reference on TCAD Simulation for VLSI MOSFET. … This book does an excellent job in providing the target audience with a comprehensive knowledge and the systematic approach for the design, characterization and fabrication of VLSI MOS transistors using TCAD tools. The book provides a practical and an easy way to gain an understanding of the fundamental physics and mathematics involved with TCAD tools. The book comprises detailed examples with source codes of different types of MOSFETs using TCAD device simulation tools so one can easily understand what is going on. Moreover, the book presents a comprehensive overview of compact modeling of MOS transistors for use in VLSI circuit simulation. If you are using or going to use TCAD software for VLSI MOSFET devices design and analysis, this is the book for you.""
––Dr. Mahmoud Al-Sa’di, Assistant Professor of Physics – Electronics, Berlin, Germany"The editor is correct in the assessment that any course related to TCAD simulation introducing the 'IC chain' commercial tools has to be through user manuals which is not very practical for class room teaching. Therefore, there seems to be a strong case for a text which can navigate students/researchers/professionals through various simulation phases systematically illustrating simulation principles, TCAD tool usages with judiciously selected case studies. 2. The authors involved are mostly known users of TCAD tools of Silvaco and are therefore competent to undertake the task."
––Professor A. B. Bhattacharyya, Jaypee Institute of Information Technology, Noida, India
