Introduction to VLSI Design

1. Introduction to VLSI Design • Instructor: Steven P. Levitan levitan@ee.pitt.edu • TA: Jeremiah Cessna jecst40@pitt.edu • Book: Digital Integrated Circuits: A Design Perspective; Jan Rabaey • Lab Notes: at Copycat • http://kona.ee.pitt.edu/steve/EE1192 • http://infopad.EECS.Berkeley.EDU/~icdesign/

2. Digital Integrated CircuitsA Design Perspective Jan M. Rabaey

3. Course Outline (approximate) • Introduction and Motivation • The VLSI Design Process • Details of the MOS Transistor • Device Fabrication • Design Rules • CMOS circuits • VLSI Structures • System Timing • Real Circuits and Performance

4. Reference Books • Principles of CMOS VLSI Design: Neil Weste and Kamran Eshraghian • CMOS: Baker, Li, Boyce • Application Specific Integrated Circuits: Smith • The Design and Analysis of VLSI • Circuits: Lance Glasser and Daniel Dobberpuhl • Introduction to VLSI Systems: Carver Mead & Lynn Conway • NewsGroups: comp.lsi, comp.lsi.cad

5. Software • Magic • Unix Based • Interactive Design Rule Checking • Circuit Extraction • Supported Technology files • Spice • Well known and disliked • Spice 3 allows user models • Good support/documentation • Interface with Magic extraction • Irsim • Switch / Switched - Resistor level • Fast functional validation • Good interface with Magic

6. Digital Integrated Circuits © Prentice Hall 1995 Introduction The First Computer

7. Digital Integrated Circuits © Prentice Hall 1995 Introduction ENIAC - The first electronic computer (1946)

8. Digital Integrated Circuits © Prentice Hall 1995 Introduction Evolution in Complexity

9. What is “CMOS VLSI”? • MOS = Metal Oxide Semiconductor (This used to mean a Metal gate over Oxide insulation) • Now we use polycrystalline silicon which is deposited on the surface of the chip as a gate. We call this “poly” or just “red stuff” to distinguish it from the body of the chip, the substrate, which is a single crystal of silicon. • We do use metal (aluminum) for interconnection wires on the surface of the chip.

10. CMOS:Complementary MOS • Means we are using both N-channel and P-channel type enhancement mode Field Effect Transistors (FETs). • Field Effect- NO current from the controlling electrode into the output • FET is a voltage controlled current device • BJT is a current controlled current device • N/P Channel - doping of the substrate for increased carriers (electrons or holes)

11. N-Channel Enhancement mode MOS FET • Four Terminal Device - substrate bias • The “self aligned gate” - key to CMOS

12. VLSI:Very Large Scale Integration • Integration: Integrated Circuits • multiple devices on one substrate • How large is Very Large? • SSI (small scale integration) • 7400 series, 10-100 transistors • MSI (medium scale) • 74000 series 100-1000 • LSI 1,000-10,000 transistors • VLSI > 10,000 transistors • ULSI/SLSI (some disagreement)

13. Digital Integrated Circuits © Prentice Hall 1995 Introduction Intel 4004 Micro-Processor

14. Digital Integrated Circuits © Prentice Hall 1995 Introduction Evolution in Transistor Count

15. Scale Example • Consider a chip size of 20mm X 20mm • Consider a transistor size of 2um X 2um • With area for wires, etc. • 1x108 transistors / chip • Or - plot at 1 transistor : 1 mm • 1 chip : 20 meter x 20 meter plot

16. Digital Integrated Circuits © Prentice Hall 1995 Introduction Intel Pentium (II) microprocessor

17. VLSI Design • But the real issue is that VLSI is about designing systems on chips. • The designs are complex, and we need to use structured design techniques and sophisticated design tools to manage the complexity of the design. • We also accept the fact that any technology we learn the details of will be out of date soon. • We are trying to develop and use techniques that will transcend the technology, but still respect it.

18. The Process of VLSI Design: Consists of many different representations/Abstractions of the system (chip) that is being designed. • System Level Design • Architecture / Algorithm Level Design • Digital System Level Design • Logical Level Design • Electrical Level Design • Layout Level Design • Semiconductor Level Design (possibly more) Each abstraction/view is itself a Design Hierarchy of refinements which decompose the design.

19. Digital Integrated Circuits © Prentice Hall 1995 Introduction Design Abstraction Levels

20. Tools Editors Simulators Libraries Module Synthesis Place/Route Chip Assemblers Silicon Compilers Experts Logic design Electronic/circuit design Device physics Artwork Applications - system design Architectures Help from Computer Aided Design tools

21. New Design Methodologies • Methodologies which are based on: • System Level Abstractions v.s. Device Characteristic Abstractions • Logic structures and circuitry change slowly over time • trade-offs do change, but the choices do not • Scalable Designs • Layout techniques also change slowly. • But the minimum feature size steadily decreases with time (also Voltage, Die Size, etc.)

22. Design Approaches • Custom • full control of design • best results, slowest design time. • Semi-custom (std cell) • use Cell libraries from vendor • cad tools, faster design time • Gate Array • fastest design time • worst speed/power/density • best low volume (worst high volume) • EPLA/EPLD - FPGA - electrically programmable (in the field) -

23. Close up of Intel Chip? Time Magazine, July 1998

24. Digital Integrated Circuits © Prentice Hall 1995 Introduction Evolution in Speed/Performance

25. Technologies • Bipolar (BJT) • TTL, Schottky • ECL • I^2 L • Dual Junction, current controlled devices • MOS (FET unipolar) • NMOS, PMOS • CMOS <== our course • Single Junction voltage controlled devices • GaAs (typically JFET’s) • OEIC’s - MQW’s, Integrated Lasers,?

26. Digital Integrated Circuits © Prentice Hall 1995 Introduction Silicon in 2010 Die Area: 2.5x2.5 cm Voltage: 0.6 V Technology: 0.07 m

27. SIA -National Technology Roadmap for Semiconductors

28. SIA -National Technology Roadmap for Semiconductors 8 inch 18 inch

29. SIA -National Technology Roadmap for Semiconductors

30. SIA -National Technology Roadmap for Semiconductors

31. SIA -National Technology Roadmap for Semiconductors

32. SIA -National Technology Roadmap for Semiconductors