Jan M. Rabaey Digital Integrated Circuits A Design Perspective

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction 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

The First Computer Digital Integrated Circuits© Prentice Hall 1995 Introduction

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

Evolution in Complexity Digital Integrated Circuits© Prentice Hall 1995 Introduction

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction 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.

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction 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 l FET is a voltage controlled current device l BJT is a current controlled current device –N/P Channel - doping of the substrate for increased carriers (electrons or holes)

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction N-Channel Enhancement mode MOS FET –Four Terminal Device - substrate bias –The “self aligned gate” - key to CMOS

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction VLSI:Very Large Scale Integration l Integration: Integrated Circuits »multiple devices on one substrate l How large is Very Large? –SSI (small scale integration) l 7400 series, transistors –MSI (medium scale) l series –LSI 1,000-10,000 transistors –VLSI > 10,000 transistors –ULSI/SLSI (some disagreement)

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

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

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction Scale Example l Consider a chip size of 20mm X 20mm l Consider a transistor size of 2um X 2um »With area for wires, etc. l 1x10 8 transistors / chip l Or - plot at 1 transistor : 1 mm –1 chip : 20 meter x 20 meter plot

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

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction 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.

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction 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.

Design Abstraction Levels Digital Integrated Circuits© Prentice Hall 1995 Introduction

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction Help from Computer Aided Design tools l Tools »Editors »Simulators »Libraries »Module Synthesis »Place/Route »Chip Assemblers »Silicon Compilers l Experts »Logic design »Electronic/circuit design »Device physics »Artwork »Applications - system design »Architectures

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction New Design Methodologies l Methodologies which are based on: »System Level Abstractions v.s. Device Characteristic Abstractions –Logic structures and circuitry change slowly over time l trade-offs do change, but the choices do not »Scalable Designs –Layout techniques also change slowly. l But the minimum feature size steadily decreases with time (also Voltage, Die Size, etc.)

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction Design Approaches –Custom l full control of design l best results, slowest design time. –Semi-custom (std cell) l use Cell libraries from vendor l cad tools, faster design time –Gate Array l fastest design time l worst speed/power/density l best low volume (worst high volume) –EPLA/EPLD - FPGA - electrically programmable (in the field) -

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction Close up of Intel Chip? Time Magazine, July 1998

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

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction Technologies –Bipolar (BJT) l TTL, Schottky l ECL l I^2 L –Dual Junction, current controlled devices l MOS (FET unipolar) »NMOS, PMOS »CMOS <== our course –Single Junction voltage controlled devices l GaAs (typically JFET’s) l OEIC’s - MQW’s, Integrated Lasers,?

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

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction SIA -National Technology Roadmap for Semiconductors

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction SIA -National Technology Roadmap for Semiconductors 8 inch18 inch

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction SIA -National Technology Roadmap for Semiconductors

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction SIA -National Technology Roadmap for Semiconductors

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction SIA -National Technology Roadmap for Semiconductors

Introduction to VLSI Design© Steven P. Levitan 1998 Introduction SIA -National Technology Roadmap for Semiconductors