Microelectronics Research and Development

March 1986

NTIS order #PB86-205200
Recommended Citation:

U.S. Congress, Office of Technology Assessment, Microelectronics Research and

Development–A Background Paper, OTA-B P-C IT-40 (Washington, DC: U.S. Government Printing Office, March 1986).

Library of Congress Catalog Card Number 86-600509

For sale by the Superintendent of Documents

U.S. Government Printing Office, Washington, DC 20402
Foreword

Microelectronics, the fundamental! building block of today’s pervasive information technologies, has progressed at a tremendous rate over the last few decades and has become a vital part of U.S. commerce and defense. This fast-changing

field depends critically on aggressive research and development (R&D) programs.

Federal participation in microelectronics R&D is twofold: the government directly funds a significant fraction of the activities, and several Federal policies indirectly affect private support of R&D. Hence, Congress has a major role to play

in microelectronics R&D—a role that can be illuminated by a better understanding of today’s activities in this area.

In November 1984, the House Committee on Science and Technology asked

OTA to prepare a background paper on microelectronics R&D as a follow-on to

the OTA assessment of Information Technology R&D: Critical Trends and Issues, released in February 1985. This background paper describes the current state

of research and development in microelectronics by examining the range of R&D

efforts and the sources of Federal and private support for R&D. It also presents

potential policy concerns that stem from existing arrangements for direct Federal support and from changes underway in microelectronics R&D.

Many members of the diverse microelectronics community, spanning the spectrum from basic research to applied development, contributed their knowledge,

insight, and viewpoints to this background paper. These included scientists, engineers, managers, and observers in Federal agencies and laboratories, industry,

universities, and other organizations. OTA is pleased to thank all participants

for their assistance. However, OTA assumes full responsibility for the contents

of this study.

Ii;
OTA Microelectronics Research and Development Staff

John Andelin, Assistant Director, OTA

Science, Information, and Natural Resources Division

Fred W. Weingarten, Communication and Information Technologies Program Manager

Project Staff

Arati Prabhakar, OTA Fellow and Analyst

Contractor

Susan P. Walton, Editor

Administrative Staff

Elizabeth A. Emanuel Shirley Gayheart*

Patricia M. Keville Audrey Newman

*Deceased, Dec. 11, 1985.

iv
Reviewers

John A. Armstrong

Vice President, Logic and Memory

IBM Watson Research Center

Donald S. Beilman

President

Microelectronics Center of North Carolina

Arpad A. Bergh

Division Manager, Device Science and

Technology Research

Bell Communications Research

Eliot D. Cohen

Navy Director, Very High Speed

Integrated Circuits Program

Space and Naval Warfare Systems

Command

Larry R. Cooper

Program Manager, Electronics Division

Office of Naval Research

Kenneth L. Davis

Head, Electronics Division

Office of Naval Research

Charles B. Duke

Senior Research Fellow

Xerox Webster Research Center

James M. Early

Scientific Advisor to the Director

Fairchild Research Center

Jeffrey Frey

Professor, Electrical Engineering

Cornell University

Paolo Gargini

Coordinator, One Micron Program

Intel Corp.

George H. Heilmeier

Senior Vice President and

Chief Technical Officer

Texas Instruments, Inc.

Evelyn Hu

Professor, Electrical and Computer

Engineering

University of California at Santa Barbara

Robert W. Keyes

Research Staff Member, Semiconductor

Science and Technology

IBM Watson Research Center

Jack S. Kilby

Dallas, Texas

Conilee G. Kirkpatrick

Director, Advanced Technology

Implementation

Rockwell Microelectronics R&D Center

Fred W. Kittler, Jr.

Vice President

J.P. Morgan Investment

Paul Losleben

Assistant Director, VLSI

Defense Advanced Research Projects

Agency

Noel MacDonald

Professor, Electrical Engineering

Cornell University

Kevin J. Malloy

Program Manager

Air Force Office of Scientific Research

Thomas C. McGill

Professor, Applied Physics

California Institute of Technology

Carver A. Mead

Professor, Computer Science

California Institute of Technology

Robert E. Nahory

District Research Manager, Optical

Properties of Semiconductors Research

Bell Communications Research

Martin A. Pollack

Head, Photonic Devices Research

Department

AT&T Bell Laboratories

Richard A. Reynolds

Director, Defense Sciences Office

Defense Advanced Research Projects

Agency

Anthony A. Immorlica, Jr.

Director, Microelectronics Center

McDonnell Douglas Corp.
Sven A. Roosild

Assistant Director, Electronic Sciences

Division

Defense Advanced Research Projects

Agency

Joseph A. Saloom

Senior Vice President

M/A-COM

George M. Scalise

Senior Vice President and Chief

Administrative Officer

Advanced Micro Devices

Donald J. Silversmith

Director, Solid State and Microstructures

Engineering Program

National Science Foundation

Michael A. Stroscio

Program Manager, Electronics Division

Army Research Office

Other Contributors

Robert S. Bauer

Manager, Integrated Optoelectronics

Xerox Palo Alto Research Center

Jules A. Bellisio

Division Manager, Digital Signal

Processing Research

Bell Communications Research

Robert D. Burnham

Research Fellow

Xerox Palo Alto Research Center

Praveen Chaudhari

Vice President, Science

IBM Watson Research Center

Melvin I. Cohen

Director, Interconnection Technology

Laboratory

AT&T Bell Laboratories

Robert Dennard

IBM Fellow

IBM Watson Research Center

James V. DiLorenzo

Vice President, Research and Development

Microwave Semiconductor Corp.

Jimmie R. Suttle

Director, Electronics Division

Army Research Office

Paul Turner

Manager, Technology Assessment

Xerox Palo Alto Research Center

Horst R. Wittmann

Director, Electronic and Material Sciences

Air Force Office of Scientific Research

Edward D. Wolf

Professor and Director, National Research

and Resource Facility for Submicron

Structures

Cornell University

Dean Eastman

IBM Fellow

IBM Watson Research Center

Lester F. Eastman

Professor, Electrical Engineering

Cornell University

Barry K. Gilbert

Special Purpose Processor Development

Group

Mayo Foundation

Kenneth L. Guernsey

General Partner

Hambrecht & Quist

Richard Henderson

Hughes Research Laboratories

M.P. Lepselter

Director, Advanced LSI Development

Laboratory

AT&T Bell Laboratories

Michael A. Littlejohn

Professor, School of Engineering

North Carolina State University

vi
James W. Mayer

Professor, Materials Science and

Engineering

Cornell University

James H. McAlear

President

Gentronix Laboratories, Inc.

James Meindl

Professor

Stanford University

C. Joseph Mogab

Microwave Semiconductor Corp.

Gordon E. Moore

Chairman and Chief Executive Officer

Intel Corp.

Stephen Nelson

Director of Research

Cray Research, Inc.

Gregory H. Olsen

President

Epitaxx, Inc.

Phil Reid

TRW

John B. Salazar

Vice President, Corporate Banking

Bank of America

George E. Smith

Head, MOS Device Department

AT&T Bell Laboratories

Louis Toth

Director, Ceramics and Materials Program

National Science Foundation

P. K. Vasudev

Senior Staff Engineer

Hughes Research Laboratories

William D. Warters

Assistant Vice President, Communications

Systems and Network Technology

Bell Communications Research

Hugh A. Watson

Head, VLSI Processing Technology and

Fabrication Department

AT&T Bell Laboratories

Benjamin A. Wilcox

Assistant Director, Materials Science

Division

Defense Advanced Research Projects

Agency

Gerald L. Witt

Program Manager

Air Force Office of Scientific Research

Irving Wladawsky-Berger

Vice President, Systems

IBM Watson Research Center

Rainer Zuleeg

Microelectronics Center

McDonnell Douglas Corp.

OTA Reviewers

Lauren W. Ackerman Jim Dray Eugene Frankel

Research Analyst Research Analyst Senior Analyst

John A1ic Greg Eyring Chuck Wilk

Project Director Project Director Project Director

Earl Dowdy

Research Analyst

vii
Contents

Chapter Page

1. ISSUES IN MICROELECTRONICS

RESEARCH AND DEVELOPMENT,,. 1

Main Findings of the Study: Trends

in Microelectronics R&D . . . . 1

Findings About Institutional Support . 1

Findings About Technological Trends 2

Trends in Fabrication Technology .,. 2

Trends in Design . . . . . . . . . . . 2

Potential Policy Concerns . . . . . . . . . . 3

Federal Response to Changes in

Microelectronics R& D . . . . . . . . . . . . 3

Federal Response to Changes

in the Industry . . . . . . . . . . . . 3

Federal Response to Technological

Trends. . . . . . . . . . . . . . . . . . . . . . 5

Direct Federal Support for Microelectronics R&D: Policy Questions 5

Multiple Sources of Federal Funding:

Pros and Cons, . . . . . . . . . . . . . 5

Questions Raised by Department

of Defense Activities . . . . . . . . . 6

2. INTRODUCTION: MICROELECTRONICS

TECHNOLOGY AND R&D . . . . . . . . 9

The Impact of Microelectronics and

Evolution of the Industry . . . . . . . 9

The Nature of Research and Development

in Microelectronics . . . . . . 10

3.CURRENT RESEARCH AND

DEVELOPMENT ACTIVITY . . . . . . 11

Advanced Silicon Integrated Circuits, . . . 11

Circuits and Packaging, . . . . . . . . 11

Design and Fabrication Processes . . . . 12

Circuits for Specific Markets . . . . . . . 12

Microelectronics Based on Gallium

Arsenide and Other Compound

Semiconductors ..,..., . . . . . 12

GaAs Digital Integrated Circuits ..., 13

Optoelectronics. . . . . . . . . . . . . . . . . 14

Discrete Optoelectronic Devices . . . 14

Integrated Optoelectronics 15

Superlattices andOtherQuantumEffect Structures. . . . . . . . . . . . . . . . 15

Microwave Devices ..., . . . . ..., . 16

Nonsemiconductor Integrated Circuit

Technologies . . . . . . . . . ., ..., 16

Josephson Junctions . . . . . . . . . . . . . . . . 16

Biomolecular Electronics. . . . . . 16

Chapter Page

4.INSTITUTIONAL SUPPORT FOR

MICROELECTRONICS R&D . . . . . . . . . . 19

Federal Support, . . . . . . . . . . . . . . 19

Department of Defense ., . . . . . 19

Research for the Navy, Air Force,

and Army. . . . . . . 20

Defense Advanced Research

Projects Agency . . . . . . . . . . . 20

DOD Special Programs . . . 21

National Science Foundation ., . . 22

Private Sector R&D . . . . . . . . . . . . . . . . . . 23

Captive Manufacturers . . . . ., . . ., . 23

Merchant Companies. ..., . . . ., 24

Cooperative R&D . . . . . . . . . . . . . . . . . . . . 25

Universities and R&D, . . . . . . . . . . . . . . . . 25

Foreign Activities . . . . . 26

Appendix Page

A. CURRENT MICROELECTRONICS

TECHNOLOGY . . . . . . . . . . . . . . . 27

Electronics Technology From Vacuum

Tubes to Integrated Circuits 27

Microelectronic Devices . 28

Types of Integrated Circuits. ., ., . 28

Other Semiconductor Devices . . . 31

Technologies To Produce Semiconductor

Microelectronics, . . . . . . . 31

Circuit Design,..,.. . . . . . . 31

Chip Fabrication ., . . . . 32

B. GLOSSARY OF TERMS . . . . . . . . 35

Table

Table No. Page

A-1. Levels of Integration . . . . 29

Figures

Figure No. Page

1. Periodic Table of the Elements . 13

A-l. Generations of Electronics

Technology. . . . . . ..., . . . . . . . 27

A-2. Types of Microelectronic Products . . . 28

A-3. Microscopic Sizes .. . . . . . . . . . . . . . 30

A-4. First of Four Mask Processes

To Make an N-Channel MOSFET...... 32

Vlll
Chapter 1

Issues in Microelectronics

Research and Development

Microelectronics is the cornerstone of the information technologies that pervade virtually

every aspect of contemporary life. These computer and communications technologies are

the basis for changes such as automation,

energy conservation, and pollution control in

offices, factories, automobiles, and homes; supercomputers for applications from weather

prediction to computational research; new capabilities in financial services; new means of

storing and playing back audio and video

recordings; advanced telephone and television

systems; and complex weapons systems for

national defense. Each of these areas is critically dependent on microelectronics technology. Furthermore, the microelectronics industry—and the industries that depend on it—

are vital to the U.S. economy.

Research and development (R&D) efforts

have fueled progress in microelectronics technology at an extraordinary rate. Since the invention of the integrated circuit (IC) 27 years

ago, the capabilities of these devices have

more than doubled every 2 years. Currently,

an IC with several hundred thousand components can be purchased for a few dollars-less

than the 1950’s price for a single component.

The Federal Government has historically

played vital roles, some direct and some indirect, in microelectronics research and development. These multiple involvements make it

important to understand both the structure

of institutional support and the implications

of current technological trends in considering

the many Federal policies that affect microelectronics R&D.

Today, many factors, including shifts in industry structure and limitations posed by

technological trends, raise questions concerning the types and levels of Federal support for

microelectronics R&D. To address these issues, this OTA background paper, requested

by the House Committee on Science and Technology, describes the current state of microelectronics research and development by examining the technologies emerging from R&D

efforts and the range of institutional support

for R&D. Although other relevant Federal policies are discussed to some extent, the primary

focus of the paper is the role of direct Federal

support for microelectronics R&D.

This chapter: 1) summarizes the OTA findings, and 2) discusses potential Federal policy implications that they suggest.1

1 In this paper, the term “microelectronics’ is used to describe

miniature electronic devices in general, Readers whose background in the technology is limited may wish to review app.

A before proceeding.

MAIN FINDINGS OF THE STUDY:

TRENDS IN MICROELECTRONICS R&D

Findings About Institutional Support universities all contribute in different ways to

A broad range of organizations supports progress in the field. Among international

microelectronics R&D. In the United States, activities, Japanese R&D efforts predominate;

Federal agencies and laboratories, private several European nations also support microfilms, cooperative research organizations, and electronics research and development.
2

Within the Federal Government, the Department of Defense (DOD) sponsors the

largest share of microelectronics R&D. Federal funds from various sources support work

in Federal laboratories, industry, universities,

and cooperative organizations.

Private sector R&D in the United States encompasses a spectrum of activities in both vertically integrated companies and merchant

firms.2 Vertically integrated companies generally support a full range of activities from

basic research to applied development, although the types and levels of R&D vary

widely from company to company. Merchant

firms tend to limit their R&D to the last stages

of development. Some companies in each category support and participate in R&D in cooperative organizations and in universities in

addition to their onsite efforts.

OTA identified four basic changes occurring

in institutional support for microelectronics

R&D in the United States:

1.

2.

In the last few years, many factors have

converged to alter the structure of the

microelectronics industry. Chief among

these is the Japanese challenge to U.S.

competitiveness, which has led to increased shares of U.S. and international

markets for Japanese companies and, consequently, reduced profits for U.S. companies. This may be leading to decreased

R&D efforts by the industry.

The exceptional capability of Japanese

companies to transform research concepts

into products is well established in microelectronics. Now, there is also growing

evidence that Japanese basic research efforts are outpacing U.S. efforts in some

areas of microelectronics, e.g., optoelectronics.

*“Vertically integrated” in this context refers to a company

that makes microelectronics to use in the products that it sells,

e.g., a computer company that makes integrated circuits for

its computers. The microelectronics division of such a company

is often termed a captive manufacturer. Some vertically integrated companies also sell their microelectronic products to

others in addition to using them internally. A merchant firm,

in contrast, makes microelectronics primarily to sell to other

end users.

3. Because of international competition and

limited resources for equipment and personnel, cooperative research efforts are

gaining popularity as a means to bolster

R&D. These activities, which typically involve cooperation among different industrial, academic, and Federal organizations, represent a relatively new approach

to R&D in the United States.

4. The deregulation of the telecommunications industry is affecting R&D in microelectronics-related areas. AT&T Bell Laboratories’ efforts are becoming more

closely tied to products than were research efforts at the predivestiture Bell

Laboratories. The role of Bell Communications Research is still not completely

known.

Findings About Technological Trends

Microelectronics can be separated into two

related parts: 1) fabrication technology, including materials, devices, and circuits; and 2) chip

architecture or design. Advances are taking

place in both aspects of the technology.

Trends in Fabrication Technology

Over the next two decades, the primary

technological trend in the physical structure

of microelectronics is likely to be continued

miniaturization of silicon integrated circuits.

Because this scaling down of the dimensions

of ICs has been the key to better and less

expensive chips, it has been the basis of

progress in microelectronics over the last 25

years. OTA found that, according to experts,

this trend will continue for the next 5 to 10

years and then will begin to level off in approximately 15 years, when minimum dimensions

are between one-tenth and one-fifth of a

micron-about one-tenth of the minimum size

currently in production. (A micron is onemillionth of a meter. See figure A-3 in app. A.)

OTA identified several other technological

trends related to this central finding. Development activities expected to influence the industry soon center on advanced manufacturing techniques required to fabricate circuits
with smaller and smaller dimensions. These

advances represent incremental changes in

current silicon IC technology.

Mid- to long-term R&D efforts, which focus

on significantly different technologies with

promise for the next generation of microelectronics, are centered on:

● digital and analog (microwave) integrated

circuits made from gallium arsenide

(GaAs),

• optoelectronics, and

● quantum-effect structures.

OTA found that few microelectronics experts

expect GaAs integrated circuits to replace silicon digital ICs. Rather, they believe that the

two types of ICs will meet complementary

needs.

The outlook for technologies based on materials other than semiconductors appears

limited for the next few decades. R&D activities in Josephson junction technology, once a

major contender for the next generation of ICs

for computers, are currently receiving limited

attention. Efforts in bimolecular electronics

are only exploratory today, and their promise

speculative. Most experts agree that they will

not come to fruition in the next few decades,

if ever.

3

Trends in Design

While circuits continue to shrink and begin

to reach limitations, the power of design tools,

and hence the flexibility of IC design, will continue to grow rapidly, OTA found. Users have

been limited to building systems out of standard ICs and other components in the past.

Now, complex new design systems coupled

with advanced manufacturing capabilities allow users to configure chips to perform specialized tasks. Progress in this area will hinge

on R&D activities in design software.

Merchant manufacturers are currently pursuing the expanding markets for application-specific ICs (ASICs), which include custom and semicustom chips. As the capabilities

of design systems and the networks that link

them to manufacturing facilities expand, an

engineer will probably be able to design an IC

for a specific need from a workstation, transmit the design to a silicon foundry, and receive

the completed special chip within a short time

and for low cost. This level of flexibility could

open the door to a whole new genre of electronic capabilities.

POTENTIAL POLICY CONCERNS

The state of research and development in

microelectronics raises several potential policy concerns about the Federal role. One set

of issues arises from the changes occurring in

microelectronics R&D; a second set centers on

ongoing direct Federal support for microelectronics R&D.

Federal Response to Changes in the Industry

In the early days of the merchant IC industry, that part of the microelectronics community generally tried to minimize its interaction

with the Federal Government. In recent years,

however, changes in the industry have shifted

the relationship between the government and

merchant firms, making it necessary for each

to attend more closely to the other: This sigFederal Response to Changes in nifies wider recognition of the impact of FedMicroelectronics R&D eral policy on the industry and a resulting gem

Governmental policies need to recognize the eral trend toward increased reliance on Federal

changes underway in microelectronics, both in policy by the industry.

the industry’s support of and need for R&D, Because Japanese competition is the greatand in the emerging technological trends. est challenge-that U.S. merchant microelec-
4

tronics companies face today, it is the focal

point of interactions between the industry and

the Federal Government. The U.S. industry

has, in the last few months, asked the government for help in changing the trade imbalance

in three separate cases.3 Another pressing concern is the high cost of capital in the United

States relative to Japan.

The current problems that the U.S. companies face pose a paradox. Although R&D, a

long-term investment, cannot solve industry’s

immediate problems, it is a crucial ingredient

in industrial competitiveness. Without continued strength in R&D, solutions to the nearterm problems will only delay the decline of

the U.S. companies. Yet microelectronics firms

that are struggling to survive are likely to neglect R&D activity in the face of more immediate and pressing problems. For example,

they may find it difficult to justify funding

R&D while cutting jobs at an unprecedented

rate. This may lead to a deterioration of the

industrial R&D base.

Federal policies that affect the amount of

R&D available to private companies can be

categorized as follows:

●

●

policies that generally strengthen the

companies by making them more competitive, and thus assuring sufficient profits to support R&D (e. g., international

trade policies and mechanisms to lower

capital costs);

policies to ease the financial burden or

lower the risks of private R&D (e.g., the

tax treatment of R&D4 and intellectual

property protections); and

‘Semiconductor Industry Association, “Japanese Market Barriers in Microelectronics: Memorandum in Support of a Petition Pursuant to Section 301 of the Trade Act of 1974 As

Amended, ” June 14, 1985; “Japanese Accused on Chips, ” New

York Times, June 27, 1985, p. Dl; and “EpROM Makers File

Claim Against Japanese ‘Dumping’, ” Electronic News, Oct. 7,

1985, p. 1.

‘Since 1981, firms have been allowed tax credits on increased

expenses for research and development, enhancing the R&D

spending power of these companies. This R&D tax credit expired at the end of 1985.

‘Pressure from the microelectronics industry spurred Congress to legislate a new form of intellectual property protection in the Semiconductor Chip Protection Act. The act, signed

into law in November 1984, protects masks (used to fabricate

ICs) from unauthorized copying, and so offers manufacturers

an additional incentive to come out with new products by protecting returns on R&D investments.

● direct Federal funding for R&D, the results of which are available to private

companies.

The first two types of Federal involvement are

indirect ways to make R&D investment easier for companies; the third approach funds

R&D directly.

The lion’s share of direct Federal support for

microelectronics R&D comes from the Department of Defense, and is therefore driven by

military requirements. In general, DOD-sponsored basic research serves both military and

commercial goals. Development activities for

military microelectronics, in contrast, do not

overlap completely with activities for commercial needs. For example, low-cost, high-volume

production capabilities are a high priority for

the commercial manufacture of integrated circuits, but the major DOD program to advance

IC technology, the Very High Speed Integrated Circuit (VHSIC) program, focuses on

design and fabrication of a small volume of

highly specialized ICs for use in military

systems.

The DOD style for funding microelectronics

R&D, characterized by long-term investment

in R&D with a clear connection to end uses,

appears to have been highly successful for

achieving military goals. Some members of the

microelectronics community would, therefore,

like to see the Federal Government aim a similar level of support at commercial needs—a

point of view that has gained momentum in

the face of the current pressures on the industry. They cite the influential Japanese Ministry of International Trade and Industry

(MITI) as a useful model. But opinions in the

microelectronics community diverge sharply

on this topic. Opponents of further direct Federal involvement in microelectronics R&D for

the industry argue that the results of R&D will

meet commercial needs and will be available

to industry only if the commercial sector

directs and carries out the work itself. They

view the MITI model as unacceptable in the

American context, given the vast differences

in industry-government relationships between

Japan and the United States.

One example of a plan to start to bridge this

difference of opinion comes from the Semicon-
—

5

ductor Research Corp. (SRC), a cooperative This has already occurred in the case of

R&D organization directed by microelectron- GaAs digital integrated circuits research led

ics industry leaders. SRC currently supports by the Defense Advanced Research Projects

R&D at universities with funds from its mem- Agency (DARPA). The microelectronics comber companies. In the next few years, it may munity had conducted relatively little research

ask the Federal Government to match this lev- on integrated circuits made from gallium

el of support. The doubled budget would be arsenide before 1982 when DARPA decided,

administered solely by SRC, which would soothe based on the results of 6 years of GaAs basic

at least the concerns of SRC’s member com- research that they had sponsored, to fund a

panics about the selection of research topics series of pilot production lines to demonstrate

and the availability of results.6 the feasibility of using GaAs for ICs. This announcement kindled the interest of a variety

Federal Response to Technological Trends

.

of organizations, and several defense elecLimitations to growth that stem from technological trends are less immediate than the

economic problems that the industry faces,

but they too pose questions about the appropriate Federal role. The shrinking of circuitry on silicon chips, on which progress has

hinged thus far, has required enormous innovation, chiefly in manufacturing technology

and engineering exploitation of the concepts

for transistors and circuit integration. But

progress in fabrication technology beyond the

limits of silicon scaling will demand a wider

range of more basic R&D activities.

This technological factor may drive expanded Federal participation in R&D for potential alternative microelectronics technologies. This could take many forms, including

policies to encourage basic research in industry or greater direct Federal R&D funding. Alternatively, Federal agencies may select specific areas in which to focus support without

significantly increasing their total funding

levels. Because the Federal Government funds

a wide range of microelectronics research efforts and interacts with a variety of R&D organizations, it can exert considerable leverage

in key areas. In these areas, some Federal

agencies might be able to lead the way for efforts by participants in the commercial sector,

universities, and other Federal agencies by targeting R&D monies.

tronics firms mobilized to build a base of activities in GaAs so that they could be involved

with the pilot lines. Three new commercial ventures have already spun off from this work.

Perhaps even more significantly, there is some

evidence that DARPA’s interest in GaAs ICs

may have helped to convince research organizations such as AT&T Bell Laboratories that

the field deserves an intensive research effort.

At about the same time, IBM turned its focus for alternative chip technology from

Josephson junctions to GaAs. In part because

of DARPA’s initiative, the activities in GaAs

ICs grew in a few years from a handful of isolated efforts in individual laboratories to large

programs sponsored by Federal agencies, industry, and universities.

Direct Federal Support for

Microelectronics R&D: Policy Questions

Ongoing direct funding of microelectronics

R&D from Federal agencies continues to raise

policy concerns. The system of multisource

support, with several different Federal agencies funding microelectronics R&D activities,

poses potential policy questions. And since the

largest amount of support comes from DOD,

many of the concerns center on the implications of defense R&D spending.

Multiple Sources of Federal Funding:

Pros and Cons

Microelectronics, like other science and engi-

‘Interview with George M. Scalise, Advanced Micro Devices neering fields, receives R&D funding from sev- and Semiconductor Research Corp., June 1985. The doubled

budget could total as much as $100 million per year, although eral different Federal agencies. Because a DeSRC’s current annual budget is only approximately$15 million. partment of Science or some other scheme for
6

centralized R&D funding is proposed and considered from time to time, it is important to

examine the pros and cons of the current

multisource arrangement. In microelectronicsrelated areas, the system generally avoids potential pitfalls and offers advantages over a

centralized system.

The potential drawbacks of the multisource

system do not pose problems at present. One

possible difficulty is wasteful duplication of

effort and competition for resources if the various agencies do not communicate their plans

to one another. The present system, too, could

confuse or inconvenience researchers seeking

funding, particularly newcomers. However,

the researchers within an area typically communicate with each other and are familiar with

the full range of activities in their area. These

informal infrastructures prevent most unnecessary duplication of effort and alert researchers to the relevant funding sources in

the area. In addition, the agencies coordinate

R&D funding through both formal and informal channels.

The advantages of distributed funding

across agencies more than compensate for the

potential problems. The arrangement provides

researchers with multiple channels for Federal

support for promising new ideas; they can turn

to a second agency if a proposal is refused by

the first. The present system also permits each

agency to fund R&D to meet its own goals or

those of its parent department. The existing

situation, with several loosely coordinated independent agencies funding different aspects

of microelectronics R&D, appears to serve its

purpose well.

Questions Raised by Department of Defense

Activities

Beyond the questions of the balance between R&D for military needs and R&D for

commercial needs, DOD activities raise two

sets of potential Federal policy issues. These

are:

1. DOD control of research and development, particularly university research

activities; and

2. the impact of the Strategic Defense Initiative (SDI) on the structure of DOD microelectronics R&D.

Keeping information about new defense

technologies within the United States is a critical concern for military security; free and wide

exchange of ideas and results is an equally

crucial ingredient in scientific research. This

dilemma is the basis of an ongoing discussion

among players both within and outside DOD,

all of whom are trying to determine the appropriate type and level of control of defense research results. Controls on universities, where

many foreign students are involved in scientific research on campus, are of particular concern. Some leading universities have banned

classified research on campus altogether as

a partial solution. Several years of debate recently resulted in a policy from the White

House (the National Security Decision Directive) which makes classification the only mechanism for control of fundamental research (i.e.,

unclassified research may not be restricted).8

The policy does not solve the problems completely. It will, however, greatly simplify the

process of determining control by reducing the

number of gray areas.

R&D funding under SDI raises two types

of concerns about DOD research: the impact

on the structure of DOD funding in microelectronics R&D, and further questions about

the treatment of university research.

The initiative’s activities in this area may

involve a major restructuring of the funds for

microelectronics R&D from the various DOD

agencies, whether or not it increases the overall level of DOD support. The transfer of the

GaAs IC pilot lines from DARPA to the SD I

Organization (SD IO) is early evidence to support this possibility. Given the wide perception that the current arrangement for DODsponsored research (with several different

agencies operating independently but commu7

1nstitute of Electrical and Electronics Engineers, “DOD’s

Perle Questions Value of Open Research on Campus,” The Institute, July 1985, p. 10.

8“White House Issues Secrecy Guideline, ” Science, vol. 230,

Oct. 11, 1985, p. 152.
7

-.

nicating with each other) works well, centralized funding of microelectronics R&D through

SDIO could decrease DOD’s effectiveness in

the field.

The fact that SD I-funded activities are designated as “advanced technology development” rather than “research” has exacerbated

the concerns about DOD controls on university research. There has been concern that

DOD would censor dissemination of all SDI

work, including university activities. From the

perspective of a group of university scientists

boycotting SDI, “the likelihood that SDI

funding will restrict academic freedom . . . is

greater than for other sources of funding. ” (A

‘From the ho~cott petition, as quoted in “Star Wars 130y -

cott Gains Strength, Science, vol. 230, Oct. 11, 1985, p. 152.

recent policy stating that SD I research at

universities will be considered ‘‘fundamental

research, ” which is to be treated in accordance

with the new National Security Decision

Directive, may have alleviated some of these

concerns. ‘0

) On the other hand, the fact that

SDI’s Innovative Science and Technology Office received approximately 2,700 preliminary

proposals from university researchers over a

period of just 3 months]’ is strong evidence

of interest from that community.

10] nstitute of E ]ectric~ and Electronics 1? ngineers, ‘‘ SI~ I

Memo Bars Controls on Most ‘Star Wars’ Research in Universities, ” The Institute, October 1985, p. 1,

‘lDwight Duston, Innovative Sciehce and Technology office,

SDI organization, personal communication, Janu~ 1986. This

number includes preliminary’ proposals in areas other than

microelectronics.
Chapter 2

Introduction: Microelectronics

Technology and R&D

THE IMPACT OF MICROELECTRONICS AND EVOLUTION

OF THE INDUSTRY

Microelectronics technology has dramatically improved the capabilities of computers

and communications systems, while also fueling the growth of completely new applications,

such as personal computers. Growing extremely fast and providing increasingly powerful and inexpensive tools to manipulate electronic signals, microelectronics has become the

cornerstone of information technologies. It is

central to such areas as:

●

●

●

●

●

computers, from powerful supercomputers, through business computers, to

inexpensive personal computers;

communications systems, including

switching stations and satellite communications;

consumer products, such as electronic

watches, video games, and pocket calculators;

control systems for industrial applications, automobiles, and home appliances;

and

military systems for national defense.

Microelectronics has become a vital part of

U.S. commerce and defense. In both sectors,

maintaining a technological edge over the rest

of the world is the only way to ensure security—whether military or economic. U.S. companies claimed approximately $14 billion of

the $26-billion world market for microelectronics in 1984. I The development of increasingly sophisticated weapons systems means

that virtually every aspect of current military

technology depends on microelectronics.

1“The ,Japan(~sc, Semiconductor hlarket and S1 ~1 :10 1 I’utition, ” presentat ion 1)~’ (;eorge Scalist’ for th~’ Sen]i~f)nduct{)r

1 ndustr} Ass{)t’lation, J ul~ !4, 19X5.

The dramatic growth of the technology has

prompted observers to describe it as the microelectronics revolution. To date, the miniaturization of circuitry, which leads to products

that perform faster and better, has been chiefly responsible for this revolution. Shrinking

the electronic devices has yielded lower cost,

expanded performance, and higher reliability.

By any measure—cost for a given function,

complexity of circuits, performance—integrated circuit (IC) technology has progressed

at a tremendous rate since its inception. In

1964, Gordon E. Moore predicted that the

number of components on a chip would continue to double annually, as it had since the

beginning of that decade. Twenty years later,

technology has not departed significantly

from Moore’s law. Experts predict a slowing

of the trend over the next 10 to 20 years.

At the same time, IC design will begin to

alter the way that system engineers use ICs.

New capabilities provided by design software,

silicon foundries, and the networks that link

them allow the end user much greater flexibility in designing chips for a specific application. This trend, coupled with changes in

fabrication technology, will affect the industry.

Many other factors, more immediate than

the scientific and engineering changes, affect

the structure of the American microelectronics

industry, especially merchant firms. These include international competition, capital requirements, capital cost, and shifting markets. U.S. microelectronics companies currently face debilitating competition from Japanese

sources, and other Asian countries (e.g., Korea) are also preparing to enter the market. At

the same time, the industry is growing stead9
10

ily more capital-intensive, since every techno- Together, these technological, international,

logical advance demands more complex equip- and economic trends and forces are altering

ment and production facilities. The high cost the microelectronics industry. The changes

of capital exacerbates this problem. Finally, mark the beginning of the maturing of the inalthough many of the markets for uses of dustry and may signal the beginning of the

microelectronic products are growing, some of end of an era of apparently limitless growth.

them grow explosively and then plummet as

rapidly, as did the video games market. These

shifts cause instability in the industry.

THE NATURE OF RESEARCH AND DEVELOPMENT

IN MICROELECTRONICS

Since microelectronics has expanded swiftly

and will continue to do so, research and development (R&D) activities play an extremely

crucial role in its progress. As the technology

and the industry mature, however, the reasons

for supporting R&D may shift. For example,

the approaching “post-shrink” era (beyond the

limits of miniaturization for silicon integrated

circuits) may demand renewed vigor in basic

research to find a successor to silicon ICs.

To suit the needs of those who use the products based on microelectronic devices, R&D

efforts in microelectronics are aimed at making circuits that:

● cost less,

• operate at higher speeds (higher frequencies),

• require less power and generate less heat,

● are more reliable and last longer, and

● carry out specific functions.

These goals are prioritized in different ways

depending on the end use. For example, low

cost is typically the chief concern for chips to

be sold in high volume, but high speed may

be the dominant requirement in making components for supercomputers, and concerns

about power consumption may dominate for

ICs intended for use in satellites.

For the microelectronics manufacturer, in

the short term, these requirements translate

into:2

●

●

●

●

●

●

making ICs with smaller component devices (i.e., smaller transistors, resistors,

capacitors, interconnections) and packing

these devices closer together on the chip;

using larger wafers so that more chips can

be made on a single wafer;

using new processes and new equipment

in chip fabrication;

packaging chips in increasingly sophisticated ways;

designing increasingly complex circuits;

and

designing circuits that are tailored to specific applications.

Scientists and engineers involved in longer

term R&D are trying to anticipate technological needs beyond the current generation of

products. Their concerns center on topics such

new materials for microelectronics (e.g.,

gallium arsenide);

new devices to replace or augment transistors (e.g., quantum-effect devices);

new equipment to fabricate these materials and devices;

integrating optical and electronic circuitry; and

advanced design tools.

2App. A: Current Microelectronics Technology provides some

general background information on integrated circuit technology, and App. B: Glossary of Terms gives definitions for technical terms.
Chapter 3

Current Research and Development Activity

Microelectronics research and development

(R&D) activities can be separated into three

categories:

1.

2.

3.

activities to improve silicon integrated

circuits (ICs),

efforts for compound semiconductor microelectronics (primarily based on gallium

arsenide (GaAs)), and

investigations for integrated circuits

based on materials other than semiconductors.

Design activities span all three categories.

Most of the work described here is aimed at

making better digital integrated circuits.

Other semiconductor activities, such as optoelectronics and microwave devices, are also included here because they are merging to some

degree with IC technology and because all

semiconductor R&D shares a common base of

physical understanding and process technology.

ADVANCED SILICON INTEGRATED CIRCUITS

Efforts now underway to improve siliconbased microelectronics will be the first type

of R&D to have practical applications. These

efforts can be grouped in three categories of

simultaneous activities:

1. the improvement of the physical circuits

and packaging of integrated circuits,

2. the facilitation of the design and fabrication processes, and

3. the design of new types of ICs for specific

markets.

Circuits and Packaging

The process of reducing the size of devices

in ICs and increasing their packing densities

has several parts. Scientists and engineers are

developing devices–transistors, resistors, capacitors–that have feature sizes of less than

1 micron. Despite their small size, these devices must be designed to operate correctly

and to control the required amount of power.

The interconnections required to hook the devices together are also becoming increasingly

harder to make. Each connection must shrink

in width but still conduct electrical current

with virtually no resistance. The interconnections must lie closer together but still be completely isolated from each other. Designers

must lay out both the devices and the interconnections in more and more complex patterns. Finally, the package for the completed

chip must allow signals to enter and leave the

chip at high speed, so that the package itself

does not obliterate the speed advantage of the

new circuitry.

These steps have been used to scale down

silicon ICs over the past 25 years. Every new

reduction in feature size has been significantly

more difficult to achieve than the last, and

progress has been possible only through the

introduction of increasingly complex manufacturing technologies and device and circuit designs. Today’s R&D workers face the greatest challenges yet.

Few trends, however, can continue forever.

The remarkable feature of Moore’s law (the annual doubling of the number of components

on a chip) is the range over which it extends

before meeting unavoidable limits. Two technological factors limit growth. The sizes of the

individual devices and the separations between them eventually become so small that

the devices cannot function as desired. In

some instances, these dimensions are a few

dozen atom layers. The problems involved in

interconnecting the devices on a chip also

become virtually insurmountable. Together,

11
12

these make a relaxation in the rapid growth

of microelectronics technology inevitable.

Microelectronics experts do not agree on the

details and consequences of this slowdown,

but they generally do agree that these limits

will be reached during the next 10 to 20 years.

Design and Fabrication Processes

Activities to facilitate the IC design process are focused on design tools, which simplify

circuit layout for IC designers. Particularly as

the design process has grown more complex

to accommodate the millions of devices, computer-aided design (CAD) systems have become virtually indispensable. Currently, there

is no single standardized CAD system; rather,

there are several different systems built by

different groups of designers. As these systems evolve, they will simplify the design process and thereby give a wider range of users

great flexibility in creating new chips.

Fabrication technology includes the processes for depositing very thin layers of different metals, insulators, and semiconductor materials on the silicon substrate; changing the

impurity content in the semiconductor; etching the layers; and defining small features in

the layers through lithography. Current R&D

activities are exploring better techniques to

carry out each of these tasks. For example,

densely packed circuits may require new materials with special properties—high electrical

conductivity, chemical stability, particular

crystal structure—for interconnections. Also,

x-ray, electron-beam, or other lithographic

techniques may be needed to replace current

photolithography for better definition of

ultrasmall features.

Manufacturing technology is a crucial part

of these advances because progress in silicon

scaling is based on the introduction and improvement of highly sophisticated equipment.

Some examples are chemical-vapor-deposition

(CVD) and evaporation systems to grow thin

films of semiconductor crystals and metals; lithography equipment and plasma etchers to

define the ultrasmall features of the IC; and

furnaces and ion implanters to introduce the

proper impurities to the wafer.

Circuits for Specific Markets

Currently, most ICs fall into a few standard categories: logic chips, memory chips, and

microprocessors. However, as the design and

manufacturing capabilities of the IC industry

grow and become more flexible, a range of specialized integrated circuits will play a more

central role. Application-specific ICs (ASICs)

are projected to grow from their current 12 to

15 percent of the total IC market to 25 to 30

percent of the 1990 market. ’ This category of

integrated circuits includes custom chips,

which are designed from scratch for the particular application, and chips that can be

adapted by the user for the specific need. Further enhancements of the design process will

expand users’ ability to design their own ICs.

‘“A Chip Business That Is Still Growing: Innovation Spurs

Market for Application-Specific Integrated Circuits, ” Electronics, July 22, 1985, p. 40.

MICROELECTRONICS BASED ON GALLIUM ARSENIDE AND

OTHER COMPOUND SEMICONDUCTORS

From the vantage point of the chemist or umns (II-VI compounds such as cadmium telphysicist, there is a logical progression of semi- luride). (See figure 1. In this terminology, the

conductor materials in the periodic table from Roman numerals refer to the columns on the

silicon (a column IV material), to compound right side of the periodic table; e.g., “III-V”

semiconductors made from the columns refers to columns 111A and IVA. ) This proadjacent to silicon (II I-V compounds such as gression is also useful for classifying the range

GaAs), to compounds made from the next col- of R&D activities in semiconductor microelec-
13

Figure 1 .—Periodic Table of the Elements

NOTE Elements n boldface are those commonly used 10 make semiconductor material s

SOURCE Off Ice of Technology Assessment

tronics, since the most immediate development efforts focus on silicon, and longer term

work usually focuses on compound materials.

GaAs and other 111-Vs are now the basis for

a variety of discrete microelectronic devices,

as described in appendix A. Current R&D efforts involving these materials focus on.: 1)

GaAs digital integrated circuits, 2) advanced

optoelectronic devices, and 3) monolithic microwave devices. R&D on design tools, which

is critical in silicon technology, is also very important for these alternative technologies.

GaAs Digital Integrated Circuits

Digital integrated circuits based on materials other than silicon continue to receive

attention in the research community. GaAsbased integrated circuits are currently the

leading contender for next-generation technology. Even so, it is important to note that virtually no experts believe that GaAs ICs will

usurp the position of silicon for most applications.

Gallium arsenide has several intrinsic physical properties that distinguish it from silicon.

The typical devices made from GaAs operate

faster and consume less power than silicon devices. They are also less likely to malfunction

in the presence of radiation. However, since

a compound semiconductor is intrinsically

more complicated than a single-element semiconductor (silicon), GaAs is a much more difficult material to grow, to handle, and to use

to fabricate reliable devices.

At present, many barriers impede prospects

for making GaAs ICs at production capacity

compared with silicon ICs, which are readily

produced in quantity. Silicon ICs are currently

fabricated on wafers with 5- or 6-inch diameters, while 3-inch wafers are the largest current size for GaAs. Standard silicon wafers

have far fewer defects and are less brittle than

the best GaAs wafers. Some processing steps

for silicon IC technology can be adapted

directly for GaAs ICs–portions of the lithographic procedure, wafer handling, clean-room

requirements. But the steps involving other

materials, such as oxides and other insulators,

metals, and polycrystalline semiconductor

material, must be developed specifically for

GaAs. This requires a more complete understanding of the chemistry and physics of the
interfaces between these materials. In addition

to all of these fundamental difficulties, GaAs

IC technology suffers because experience with

it is very limited, relative to silicon. Many of

the problems, however, will probably be solved

as experience accrues.

The list of organizations supporting (and not

supporting) R&D in this area reveals quite

clearly the microelectronics community’s

views on the applicability of GaAs ICs. DOD

is the leading Federal supporter of research in

this field, because military applications, particularly in space, require the properties GaAs

offers: high speed for large-scale signal processing, low power to minimize bulk and energy

consumption, and radiation hardness for reliability in the presence of radiation. Major computer and communications companies-e. g.,

AT&T, IBM, and several Japanese companies

—are also investigating GaAs ICs, primarily

for use in the parts of their systems that require the highest speed, e.g., computer front

ends. Supercomputer companies, most notably Cray, are attempting to make supercomputers based on GaAs ICS. However, the

standard merchant chip makers (e.g., Intel,

Fairchild Semiconductor, Advanced Micro De

vices), which tend to concentrate almost exclusively on short-term development activities, have no onsite efforts in materials other

than silicon. Some of these companies support

longer term projects, including GaAs work, at

universities and through cooperative research

organizations. This balance of support indicates two things:

1. GaAs digital ICs are beginning to find

niche applications in a variety of areas,

and

2. they will probably not make a significant

dent in the standard IC components market for several years.

Optoelectronics

As described in appendix A, compound

semiconductors and their alloys are currently

used to make devices that convert electrical

signals to light signals and vice versa. The devices are used for optical communications and

sensor applications. R&D activities in optoelectronics fall into three categories:

1. advanced discrete light sources and detectors,

2. integrated optoelectronics, and

3. superlattices and other quantum-effect

structures.

The II I-V compound materials used for optoelectronics include GaAs, iridium phosphide

(InP), gallium phosphide (GaP), aluminum arsenide (AlAs), iridium antimonide (InSb), and

alloys of these materials, such as aluminum

gallium arsenide (AIGaAs), iridium gallium arsenide (InGaAs) and iridium gallium arsenide

phosphide (InGaAsP). Similarly, important IIVI materials include cadmium telluride (CdTe),

mercury telluride (HgTe), and their alloy, mercury cadmium telluride (HgCdTe). These materials are designated as binary, ternary, or

quaternary depending on the number of elements found in them. The alloys actually represent a range of materials; for example, half

the atoms in HgCdTe must be tellurium, but

the other half may be any combination of mercury and cadmium atoms. The properties of

the alloy generally lie between the properties

of the binary materials that compose it. The

particular composition of an alloy is typically

chosen to have a certain desired wavelength

response. The standard approach to fabricating optoelectronic devices is to grow thin

layers of ternary or quaternary alloys on a substrate of a binary material.

Discrete Optoelectronic Devices

The first optoelectronic devices for fiber

optic communications were made of GaAs

and AlGaAs. The best current devices, however, are based on different compositions of

InGaAsP grown on substrates of InP, structures that generate and detect light over a

range of wavelengths that includes those of

lowest loss (1.55 microns) and lowest dispersion (1.3 microns) in optical fibers. Since these

devices are relatively new, the materials and

processing problems have not been completely

resolved. R&D efforts in this area focus on

making devices more reliable and more toler-
15

ant of extreme environments, achieving more

precise control of the generated light, and developing production processes (with high

throughput and yield) for the devices.

The II-VI compounds are used to fabricate

long-wavelength infrared sensors because

these materials (especially HgCdTe and CdTe)

are sensitive to the wavelengths of interest—from around 1 micron to the 10- to 12-

micron range. Currently, research on these devices centers on materials properties, which

are much more difficult to control in the IIVI compounds than in other semiconductors.

Integrated Optoelectronics

Individual optoelectronic devices can be integrated and fabricated on a single substrate

much as standard electronic devices are integrated on a chip to make an IC. An integrated optoelectronic device, typically built on

a substrate of InP or GaAs, may be composed

of lasers, devices to amplify and modulate the

light signals, and light detectors. In addition,

the same chip may have purely electronic devices that process electrical signals. Such an

integrated chip has all the advantages of a conventional integrated circuit—miniaturization,

high speed, low power, fabrication reliability—and also solves the alignment and vibrational-stability requirements for the optical

elements it comprises. In addition, it brings

optical and electronic devices so close together

that signal delays between them are minimized,

allowing high speeds to be achieved.

The basic concepts for integrated optoelectronics may be extrapolated even further in

the future. Highly advanced crystal growth

and processing techniques, currently in their

infancy, could also open the door to the possibility of structures that would combine

silicon, III-V, and II-VI devices on a single

substrate. Such a scheme would allow the flexibility to use the optimal material for each portion of the complete circuit. For example, a circuit on a single chip could be composed of

InGaAsP lasers, HgCdTe light detectors, and

GaAs and silicon digital logic and memory circuits. Concepts of this sort are still in the speculative stage today.

Superlattices and Other

Quantum-Effect Structures

By using sophisticated techniques to deposit materials very precisely, crystal growers

can make layers as thin as a few layers of

atoms on a semiconductor substrate. Such a

layer is approximately one-thousandth of a micron thick-one-billionth of a meter. z Structures called superlattices are formed by growing alternating ultrathin layers of two

different materials, e.g., GaAs and AlGaAs.

Special methods such as molecular-beam

epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD) are necessary to

achieve this extreme level of control during

crystal growth. These advanced techniques

open a completely new set of options for

semiconductor materials. Varying the thickness of the layers and their composition can

yield a superlattice material with different

electronic and optical properties. Quantum

mechanical effects dominate the behavior of

the electrons in superlattices because the

structures have such small dimensions. Thus,

the electron transport processes can be dramatically different from the processes in normal material.

Currently, the range of research efforts in

this area is very wide, spanning the spectrum

from work in designing better systems for

growing these precise layers to making devices

based on superlattices. The devices include

III-V and II-VI photodetectors, lasers, and

transistors. The greatest overall contribution

of this new breed of materials will probably

stem from the fact that they can be tailormade for a particular application. Already,

they are

vantage

areas of

heralded by observers from diverse

points as one of

research today.3

the most exciting

‘F’igure A-3 in app. A shows how small a micron is.

‘For example, National .4cademy of Sciences, Committee on

Science, Engineering, and Public Policy, The Outlook for Science

and Technolo~’ 198,5; and CJeorge H. Heilmeier, “Microelectronics: End of the Beginning or Beginning of the End?” International Electron L)e\’ices Meeting, December 198L1.
16

Microwave Devices

Analog microwave devices, operating at frequencies from approximately 1 to 60 gigahertz

(a gigahertz is 1 billion cycles per second), are

commonly made from GaAs to take advantage

of the high speed that the material offers. Currently, monolithic microwave integrated circuits (MMICs) are being developed. These circuits combine various microwave devices on

a single substrate, typically GaAs. The devices

are not packed as densely as silicon devices

on a conventional digital IC, but the smallest

dimensions are about the same as or smaller

than those for silicon ICs—below 1 micron.

MMICs will fill the demand for more compact

and reliable microwave circuitry for applications in radar, transmission of television and

telephone signals, and spectroscopy. A couple

of companies have MMICs on the market already, and others plan to market them soon.4

Most recently, the Department of Defense

(DOD) announced that it will launch a major

new initiative for MMICs for defense systems.

The new program will be analogous to the

Very High Speed Integrated Circuit (VHSIC)

program, which addresses digital IC technology for DOD.

4“MMICS Save Space, Increase Reliability, and Improve Performance, ” Electronics Week, May 20, 1985, p. 52.

NONSEMICONDUCTOR INTEGRATED CIRCUIT

TECHNOLOGIES

Integrated circuits may also be based on materials other than semiconductors. Circuits

made of superconducting Josephson junctions

have been heavily investigated but are not at

present expected to find any large-scale applications in digital microelectronics. Bimolecular electronics is currently only a highly speculative field.

Josephson Junctions

A Josephson junction is an electronic device

made by sandwiching a very thin insulator between two superconductors—materials with

zero electrical resistance at very low temperatures. Like electronic devices made from

semiconductors, Josephson junctions can

switch or store electronic signals. Despite

drawbacks such as extremely low operating

temperatures, they offer several advantages

over semiconductor microelectronics. Josephson junctions can switch signals at unparalleled speeds, require very little power, and can

be scaled down to extremely small dimensions.

Computer systems based on Josephsonjunction technology were intensively researched and developed for over two decades,

most notably at IBM. However, IBM halted

all but its basic research effort in this area several years ago because packaging, manufacturing, and reliability difficulties meant

that the systems could not operate as well as

had been originally predicted. Furthermore,

while the superconducting technology was

struggling to get on its feet, silicon and gallium arsenide technologies kept progressing

at a tremendous rate. IBM’s cutbacks in this

area symbolized a significant change in the

microelectronics community’s view of IC technology beyond silicon. Currently, although

some work on Josephson junctions continues

in the United States and in Japan (especially

efforts aimed at making high-speed analog circuits), these devices are considered unlikely

candidates to pickup where silicon leaves off

in digital ICs.

Bimolecular Electronics

In contrast to semiconductor and Josephson junction technologies, the concept of using

biological systems to process electrical signals

is still in its infancy. Some researchers are

turning their attention to biological systems
17

as the extrapolation of the trend to smaller in the fabrication of extremely small strucand smaller devices leads to molecular-scale tures on semiconductors, and in electronic senstructures. sors for medical applications. But the potenAt present, large-scale bimolecular elec- tial for computers based on bimolecular

tronics is a largely speculative area. Some ex- circuitry has not yet been demonstrated.

perts envision-a role for biological materials
.

Chapter 4

Institutional Support for

Microelectronics R&D

Because microelectronics is a key commer- private, Federal, academic, and cooperative

cial and military technology, support for re- groups are active in the area. Other nations

search and development comes from many also support microelectronics R&D; Japan in

sources. In the United States, a multitude of particular is a growing presence in the field.

FEDERAL SUPPORT

The largest block of Federal funding for

microelectronics R&D comes from the Department of Defense (DOD). The National Science

Foundation (NSF) funds basic research in

areas related to microelectronics. Several other

Federal agencies and laboratories have programs to meet their specific needs, among

them the National Aeronautics and Space

Administration, the National Institutes of

Health, the National Bureau of Standards,

Lawrence Livermore National Laboratory,

and Los Alamos National Laboratory.

Department of Defense

DOD support was crucial to early successes

in microelectronics. For example, military requirements for smaller circuits were the primary force behind the development of the first

integrated circuits (ICs). While DOD has continued to fund microelectronics R&D extensively and remains the largest source of Federal support for microelectronics R&D,

support from private companies has assumed

a much larger role, and includes an entire industry that has sprung up in the last few decades. Today, military applications constitute

approximately 10 percent of the total sales of

microelectronic products. Microelectronics

technology is crucial to DOD, and its importance will grow further in the foreseeable future. According to two experts,

. . . [i]t is safe to say that there is not a single western military system that is not critically dependent for its operation on semiconductor integrated circuits. ’

Other microelectronic devices, such as sensors,

are also becoming increasingly important in

military technology.

The defense community, like other users

of microelectronics, requires high-speed integrated circuits that consume little power.

Since U.S. defense policy has long been based

on technological superiority, DOD needs the

best possible signal processing and sensor capabilities. Military end users have specific

needs as well, including products like ICs that

are immune to damage from radiation.

Each of the three services—the Navy, Air

Force, and Army—supports activities in

microelectronics R&D in DOD laboratories,

such as the Naval Research Laboratory, the

Air Force Avionics Laboratory at WrightPatterson, and the Army Electronic Device

and Technology Laboratory at Fort Monmouth, and through research agencies. Apart

from the services, DOD’s Defense Advanced

Research Projects Agency (DARPA) is heavily involved in this area. Certain aspects of

microelectronics R&D are also covered under

a few DOD special programs, such as the Very

High Speed Integrated Circuits (VHSIC) proIAlton L. Gilbert and Bruce D. McCombe, “Joint Services

Electronics Program: An Historical Perspective, prepared for

the U.S. Army Research Office, Electronics Division, April

1985.

19
20

—

gram and the Strategic Defense Initiative

(SDI).

Research for the Navy, Air Force, and Army

The Office of Naval Research (ONR), the Air

Force Office of Scientific Research (AFOSR),

and the Army Research Office (ARO) handle

scientific research for their respective

branches of the military. All three fund substantial amounts of basic research in microelectronics, with large shares of these funds

going to universities. Their areas of interest

center on materials and devices. Because the

three agencies are organized in different ways,

a completely accurate comparison of their levels of support is not possible. However, approximate annual budget figures for microelectronics-related work sponsored by AFOSR,

ONR, and ARO are $24 million, $13 million,

and $9 million, respectively.2

Part of the funding from the three services’

research offices goes to support the Joint Services Electronics Program (J SE P). They sponsor the program jointly, with each office contributing approximately one-third of the

funding. JSEP is a 38-year-old DOD program

that funds electronics research, including

microelectronics, at a group of universities. It

is designed to provide its 12 member universities with stable, long-term funding for basic

research. Total JSEP annual funding has increased since the program’s inception to $9.6

million in 1984; approximately 75 percent of

this is spent on research on integrated circuits

and other microelectronics-related areas.3

Defense Advanced Research Projects Agency

The Defense Advanced Research Projects

Agency (DARPA), which is separate from the

services, supports long-term research for general military applications, including microelectronics R&D. DARPA funds efforts at universities, industrial laboratories, and not-for-profit

organizations. One component of DARPA, the

‘~Horst R. Wittmann, Gerald I.. Witt, and Kevin J. Malloy,

AFOSR; Kenneth L. Davis and Larry R. Cooper, ONR; and Jimmie R. Suttle and Michael A. Stroscio, ARO; interviews and

discussion, April 1985 to January 1986.

‘Gilbert and McCombe, op. cit.

Defense Sciences Office (DSO) supports midto long-term work on materials, processes, devices, and circuits. Another branch, the Information Processing Techniques Office (IPTO)

sponsors activities in very large-scale integration (VLSI) design and architecture and some

production automation work.

In fiscal year 1985, DSO had a budget of approximately $34 million for microelectronics,

of which $28 million supported basic research

and the remainder funded exploratory development. About 40 percent of the total budget

went to universities for basic research. DSO

sponsors investigations of gallium arsenide

(GaAs) and other II I-V compounds and their

alloys, and work on II-VI compounds, such as

mercury telluride and cadmium telluride, and

their alloys. Many of these materials have interesting combinations of properties that can

be exploited for new applications. DARPA

also supports research on the integration of

biological materials and semiconductor electronics for ion sensors and other devices.

As of fiscal year 1985, DSO assumed responsibility for the administration of the GaAs IC

pilot lines and related activities for SDI. These

efforts were transferred to SD I from DARPA

at the end of fiscal year 1984. SDI will spend

$23 million in this area in 1985, and funding

may rise to $40 to $60 million over the next

few years, depending on the overall level of

support for SDI. Most of these funds are used

to support the GaAs IC pilot lines that were

originally established and funded by DARPA;

additionally, $2 to $3 million from this source

goes to universities for basic research

activities.4

The R&D activities supported by IPTO

cover the circuit-design and manufacturing

portions of microelectronics technology. Approximately $12 million of the funds that

IPTO puts into microelectronics goes to basic

research activities in VLSI design and architecture, most conducted at universities. In

many cases, this research has later been fun4Richard A. Reynolds and Sven A. Roosild, DARPA, interviews and discussion, October 1984 to January 1986.
neled into commercial enterprises. For example, IPTO originally sponsored the “Cosmic

Cube” parallel architecture work at the California Institute of Technology; Intel added

funding to the Federal money and is now

building and marketing a minisupercomputer

based on this architecture. In addition, IPTO

spends about $6 million per year on exploratory development in automation and fast-turnaround efforts for ICs. These funds cover work

on the Metal-Oxide-Semiconductor Implementation System (MOSIS), which gives a large

and geographically diffuse community of IC

designers, particularly at universities, access

to a silicon fabrication facility. With MOSIS,

individuals design circuits at their home facilities using a computer-aided design (CAD)

system. The design commands are transmitted

over a communication network to a manufacturing site, where the IC is fabricated. At present, designers use MOSIS to create new silicon ICs. Activities in progress will also make

possible the creation of GaAs-based ICs in a

similar systems

Since DARPA is charged with longer term

R&D responsibilities, the agency is shifting

its focus in microelectronics away from silicon

efforts and toward GaAs ICs, while also beginning some activities in more esoteric fields.

In some cases, work that DARPA initiated

and supported is being picked up by groups

more interested in near-term efforts. For example, DOD’s VHSIC program and the private Semiconductor Research Corp. (SRC) are

taking over the funding of some silicon VLSI

programs at Stanford University that were initially sponsored by DARPA.6

DOD Special Programs

In addition to the four established agencies,

DOD has a variety of special programs that

support microelectronics R&D. Examples include the Very High Speed Integrated Circuits

program and the new Strategic Defense Initiative. VHSIC is wholly dedicated to silicon

‘>Paul I,osleben, DAR PA, interview, August 1985; and presentation on ‘ L Silicon as a Medium for New Ideas, I E ~; E Systems, Man, and Cybernetics Society, Sept. 16, 1985.

‘Paul I,osleben, DARPA, interview, August 1985.

21

IC technology; SDI has microelectronics R&D

components as part of a more general mission.

DOD also recently announced the start of a

new VHSIC-like program to advance the technology of monolithic microwave ICs (MMICs)

for defense applications.

The 10-year VHSIC program was established in 1979 to address specific military

needs in microelectronics. The three services

participate in VHSIC, but the Office of the Undersecretary for Defense Research and Engineering provides overall administration.

Honeywell, TRW, IBM, Hughes, Texas Instruments, and Westinghouse are the prime

contractors for VHSIC, which is scheduled to

finish in 1989.

VHSIC has several goals. The primary technical objective is to establish processes to design and fabricate chips with characteristics

necessary for defense needs. The program also

intends to ease the adoption of these ICs in

military systems. In addition, VHSIC administrators view their program as a mechanism to encourage the commercial microelectronics sector to develop production

capabilities suited for the military market. The

program is intended to function as a bridge

between designers of military systems and the

integrated circuit community.

The technological goals of VHSIC are

divided into phases. The first phase of the program, now nearing completion, developed pilot lines for the production of ICs with 1.25

micron minimum feature sizes and provided

new chips for use in military systems. The second phase will attempt to establish pilot lines

to fabricate ICs with 0.5 micron features. At

the same time, commercial R&D activities

have been and will be developing ICs with similar feature sizes, but the VHSIC chips are designed for specific DOD applications. Although the first phase of activities took longer

to complete than originally anticipated, some

of the projects have now been carried out successfully.

Because VHSIC’s other objectives are

longer term and less concrete, their success is

harder to assess. Several signs point to
22

-.

progress; VHSIC chips are used in several military systems in each of the services. And

while VHSIC has gotten a mixed reaction

from industry over the years, the program has

drawn the attention of at least some of the

commercial IC vendors to military applications.

As conceived, VHSIC had a budget of approximately $200 million over 10 years. Subsequently, its budget has been expanded to approximately $1 billion to support a range of

additional activities. These include efforts to

encourage incorporating VHSIC technology

in military systems in the three services, the

development of a design automation system,

and work on yield enhancement.7

SDI, started in 1983, is designed to study

and perhaps deploy a space-based missile defense. Since microelectronics technology would

be central to any such system, one program

goal is the development of advanced circuitry

for space-based military operations. In addition to the DARPA GaAs work that is now

funded through the SD I program element for

sensors, SDI Innovative Science and Technology (1ST) office is preparing to support

multiple activities in microelectronics research. At present, the programs are being established, and funding levels are being debated. Although final amounts have not been

set, it is possible that 1ST will spend several

million dollars in this area over the next few

years. The funds may comprise dollars from

other DOD research pockets (e.g., DARPA, as

in the case of the GaAs IC work, or the services’ research offices), so they may or may not

constitute a net increase in the overall DOD

research funding for microelectronics. Currently, contract monitors from other DOD research agencies (primarily ONR) are administering these funds.

National Science Foundation

The National Science Foundation (NSF) is

charged with supporting research in a broad

range of science and engineering fields. Micro7Eliot D. Cohen, Navy VHSIC Program Director, interview,

July 1985, and additional comments, November 1985.

electronics R&D at NSF is funded primarily

through the Directorate for Engineering. NSF

spends approximately $23 million in areas that

include solid-state and microstructure engineering, quantum electronics, electronic materials, electrical and optical communications,

and VLSI. These funds support individuals or

small groups of researchers.

NSF established the National Research and

Resource Facility for Submicron Structures at

Cornell University in 1977 and has provided

it with about $2 million annually for the last

few years. This facility is also supported

directly by industrial sponsors and indirectly

by other Federal agencies. In addition, NSF

has recently established an Engineering Research Center at the University of California

at Santa Barbara for Robotic Systems in

Microelectronics. NSF plans to give this center up to $14 million over the next 5 years, a

sum that the university will probably augment

with support solicited from industry. The center will focus on automated systems for IC

manufacturing. 8 To some extent, these centers

are evidence of a trend at NSF to concentrate

its limited resources in a small number of large

facilities rather than granting small bundles

of money to a large number of investigators.

NSF’s style of supporting research differs

a great deal from the DOD approach. Defense

agencies tend to seek out channels-at universities, in industry, or at DOD laboratories—

to accomplish their goals, with a focus on end

uses. NSF, by contrast, is not a missionoriented agency, so it responds to proposals

from the research community. NSF’s funding

for microelectronics and related areas is quite

small compared to the total DOD support, but

these monies provide some counterbalance to

the defense dollars. And while NSF has not

played the major role in advancing the technology, it has helped to build a base of qualified scientists and engineers, e.g., by helping

new university professors get started with

small grants. This gives NSF an important

role as a broad basic-research agency.

‘Evelyn Hu, Associate Director, Center for Robotic Systems,

interview, October 1985; and NSF literature on Engineering

Research Centers.
.

23

—

PRIVATE SECTOR R&D

Many kinds of private sector organizations

are engaged in microelectronics research and

development. They may be grouped into two

broad categories:

1.

2.

captive manufacturers—the parts of

large, vertically integrated companies

that make microelectronic components for

their own products and services (typically

computers or telecommunications) or for

their defense systems applications

(termed “captive” because the primary

markets for their microelectronic products are internal); and

merchant firms-companies that make integrated circuits and other microelectronic products to sell to the full range of end

users.

These categories are not mutually exclusive.

Several companies (e.g., Texas Instruments)

make microelectronic components for internal

use as well as outside sale. However, the division helps to illuminate the nature of R&D in

many companies, since the size and goals of

the organization are key determinants of its

approach to R&D.

Today, the most prominent force changing

microelectronics companies (and thus their

R&D efforts) is Japanese competition. Merchant vendors are especially vulnerable. This

has major implications for industrial R&D.

Companies may cut back on R&D investment

as part of a general belt-tightening effort.

Paradoxically, R&D is increasingly important

in the competitive environment. Thus, the

companies are beginning to look to the Federal Government for R&D support, either

through direct funding for R&D, or through

Federal policies that ease the way for private

support, such as the tax treatment of R&D expenditures and intellectual property protections.

Captive Manufacturers

Although microelectronics technology is being applied in more and more ways, its primary uses are still concentrated in computers,

telecommunications, and military systems.

Because these uses dominate the field, most

companies with captive microelectronics operations specialize in them.

Since these firms are generally very large

and relatively stable, they tend to support a

very broad range of activities, from basic research to product development. For example,

companies such as IBM and AT&T have thousands of scientists and engineers involved in

different aspects of microelectronics R&D.

Telecommunications and computer technologies are beginning to merge because of developments in information technology and also

as a result of the recent deregulation of the

telecommunications industry. The latter development allowed new entrants into the field

and permitted AT&T, formerly excluded, to

participate in the computer marketplace. The

divestiture of AT&T also split the well-known

Bell Telephone Laboratories into two research

organizations: AT&T Bell Laboratories and

Bell Communications Research (Bellcore),

which serves the seven regional Bell operating companies jointly. Although the divestiture of AT&T officially occurred at the beginning of 1984, its long-term effects on research

are not yet completely clear. However, there

are preliminary indications of trends at the

two companies.

Some changes are clearly underway at

AT&T Bell Laboratories. R&D activities are,

overall, becoming more closely linked with

products as a result of the new competitive

environment that AT&T faces. Even so, there

is ample evidence that at least in areas related

to microelectronics the organization will continue to pursue a broad spectrum of basic research as well as development. The new environment has both negative and positive

implications for R&D. Scientists and engineers

in the research community are concerned that,

whether or not AT&T Bell Labs shifts from

basic research, it will be less likely to share

the fruits of its research with others. On the

other hand, the pressure of competition will

probably drive AT&T Bell Labs to move re-
search into new products and services faster

than it did in predivestiture years.

The prognosis for Bellcore’s role as an R&D

organization is, if anything, even less certain.

Bellcore is a unique laboratory in the United

States because it serves seven separate, highly

regulated companies. It is not directly linked

to any particular manufacturing facility, and

so will probably not experience the same shifts

in R&D as AT&T Bell Labs. In fact, Bellcore

to date exhibits signs of pursuing a vigorous

basic research program in microelectronicsand optoelectronics-related areas. But since it

is a completely new organization, Bellcore will

need several years to establish an identity in

R&D.

Other manufacturers of products for industrial and commercial use, such as Xerox and

Hewlett-Packard, also contribute heavily to

microelectronics R&D. These companies, although significantly smaller than, for example, IBM and AT&T, are still large and diverse

enough to support good-sized research efforts.

Their specific markets tend to shift the direction of R&D activities, so that each such company pursues a somewhat different research

agenda. For example, Xerox’s interest in printing technology helped the company to achieve

prominence in optoelectronics research.

Of the several captive microelectronics operations that serve the military markets for

microelectronics, many carry out DOD-funded

and internal R&D. Much of the internal R&D

is funded by Independent Research and Development (IR&D) funds which are derived

from overhead on defense R&D contracts. The

largest players in this category are such companies as Hughes Aircraft, Honeywell, Rockwell, TRW, and McDonnell Douglas. Many

other companies that are well known for their

commercial efforts are also defense contractors. Typical examples include IBM, AT&T,

and Texas Instruments.

Merchant Companies

Merchant companies sell microelectronic

products to users who incorporate them in a

variety of systems—computers, communications systems, consumer products, control

equipment, and defense systems. California’s

Silicon Valley firms (e.g., Intel and Advanced

Micro Devices) are the archetypes of this category. Generally, merchant firms have concentrated on producing standard chips (microprocessors, logic chips, and memories), which

have been used in the larger electronic systems. Custom integrated circuits, which are

designed for a user’s particular needs, have

held part of the chip market for many years.

As IC design and manufacturing become more

flexible, a wider range of application-specific

integrated circuits (ASICs), including custom

and semicustom chips, is drawing a larger

share of the market. During the 1985 slump

in IC sales, ASICs constituted the one healthy

segment of the market.9

Merchant companies, unlike their larger

counterparts, tend to limit their R&D to the

last stages of development; their central concern is getting the latest design and fabrication technologies into production. Two major

factors converge to make longer term R&D efforts improbable in these firms. First, the companies depend on the sale of only one type of

product—semiconductor devices—for their

survival. They tend to be focused, lean operations, with few discretionary dollars for basic

research in an area where even a simple experimental facility costs several million dollars.

Second, two hallmarks of the Silicon Valley

culture are the ease with which workers move

from one company to another, and the frequency with which new companies spring up.

Managers in merchant chip firms seldom find

that a heavy investment in long-term research

pays off in this fluid environment.

However, in the last several years, this community grew concerned that its needs were not

being met by universities and other basic research organizations. Manufacturing research,

for example, is increasingly crucial to the continued growth of the industry, but it had scant

support among basic research organizations.

‘“A Chip Business That Is Still Growing: Innovation Spurs

Market for Application-Specific Integrated Circuits, ” Electronics, July 22, 1985, p. 40,
To correct this, many merchant companies

today help to support external R&D activities

through different channels. For example, several merchant semiconductor firms fund university research through the Semiconductor

Research Corp. These companies also cooper2 5

ate in other R&D ventures. Several merchant

companies also independently support research projects at universities. All of these

activities center almost exclusively on aspects

of silicon technology.

COOPERATIVE R&D

Cooperative research and development

activities take different forms: organizations

that are jointly funded from several different

sources or research facilities that are shared

by different groups of workers. These joint efforts represent a relatively new approach to

R&D in the United States. In microelectronics,

several factors are driving the growing trend

toward centralized funding for R&D:

research in microelectronics requires increasingly expensive facilities, which few

participants can afford alone;

advances in microelectronics depend increasingly on multiple technical disciplines, requiring a number of persons

trained in different areas; and

cooperative research can link academia

and-industry, thereby bringing necessary

funding to universities and facilitating

the process of transferring technology

from research to development to production.

Examples of cooperative microelectronics

research organizations include the Semiconductor Research Corp. (SRC), the Microelectronics Center of North Carolina (MCNC), and

the Microelectronics and Computer Technology Corp. (MCC).10 Each of these channels

funds from a variety of commercial firms to

universities and other basic-research organizations. MCNC and MCC also carry out inhouse R&D activities.

In addition, a plethora of initiatives for

shared facilities are emerging from Federal

funding agencies, ranging from NSF, which recently reorganized to focus resources on a

group of Engineering Research Centers, to the

Innovative Science and Technology part of the

Strategic Defense Initiative Organization,

which is actively promoting the establishment

of research consortia. While many researchers

support this trend, others point out that cooperative research is hardly a panacea for

microelectronics R&D. They argue that centralization of resources threatens innovation,

and that research done by a large number of

individual investigators, who come together

in small groups to communicate and collaborate, is the most productive approach.

10The structure and Operation of these and other cooperati~re

research organizations are described fully in U.S. Congress, Office of Technology Assessment, Information Technology R&D:

Critical ‘Ii-ends and Issues, ch. 6, OTA-C IT-268 (Washington,

DC: U.S. Government Printing Office, Februar~ 1985).

UNIVERSITIES AND R&D

Universities serve two main functions in Support for research at universities comes

R&D: they perform basic research suited to from many sources, including military and

an academic environment; and they educate civilian agencies of the Federal Government,

and train students who subsequently perform industrial organizations, and combinations of

research and development in industrial, gov- these. Microelectronics research takes many

ernmental, and academic organizations. forms in this setting. Universities across the
26

Nation have individual research programs,

typically in such departments as electrical

engineering, physics, and chemistry. A handful of universities have large research centers.

These include the National Research and Resource Facility for Submicron Structures at

Cornell University, Stanford University’s Center for Integrated Systems, the Microelectronic and Information Sciences Center at the

University of Minnesota, and the Center for

Robotic Systems in Microelectronics at the

University of California at Santa Barbara.

The university role in preparing students for

the R&D community has many facets, some

of which have prompted

field of microelectronics.

disagreement in the

Although many observers view the current trend toward large

campus engineering facilities as a useful way

to train students for the activities they will

undertake in industry, some experts are concerned that this trend undermines the wellrounded education that universities ought to

provide for their students. Thus, there is an

ongoing debate about the best way for universities to fulfill this part of their mission.

FOREIGN ACTIVITIES

Foreign activities in microelectronics R&D

are so diverse that a full treatment of the topic

is beyond the scope of this paper.11 However,

several prominent features of the Japanese efforts have important implications- for U.S.

R&D in microelectronics.

Japan is the largest foreign supporter of

microelectronics R&D. Although observers

have long viewed Japanese development and

manufacturing activities as competitive with

or superior to ‘U.S. efforts in microelectronics,

they ‘had generally believed that the United

States excelled at innovation in basic research.

Now, however, Japanese basic research efforts

are drawing world-tide attention. In the words

of one panelist of the Department of Commerce’s Japanese Technology Evaluation

(JTECH) Program:

It is often said that the U.S. invents and

Japan copies. . . . [S]uch generalizations are

grossly inaccurate and certainly do not favor

a genuine understanding of our best competitor. 12

“For an extensive discussion of foreign R&D efforts in information technology, see U.S. Congress, Office of Technology

Assessment, Information Technology R&D: Critical Trends and

Issues, ch. 7, OTA-CIT-268 (Washington, DC: U.S. Government

Printing Office, February 1985).

l~Federico Capasso, AT&T Bell Laboratories, quoted in “Japan Reaches Beyond Silicon, ” ZllIIE Spectrum, October 1985,

p. 52.

Japanese companies continue to transfer research concepts to production with great

speed. In this activity, they draw extensively

from U.S. as well as Japanese basic research

results. Another JTECH panelist states,

They do not seem to have difficulties with

the “not-invented-here” syndrome that slows

technology advances into the marketplace in

the U.S.13

The United States has a harder time taking

the same advantage of Japanese work. One of

the biggest barriers to access to Japanese research by U.S. workers is the language difference.

The structure of the electronics industry in

Japan strongly affects R&D. In contrast to

the United States, Japan has almost no merchant microelectronics firms. Its large, stable,

vertically integrated companies can and do invest more heavily in long-term R&D than U.S.

merchant firms. This suggests that the challenge they pose to U.S. competitiveness will

remain and quite possibly increase.

“Robert S. Bauer, Xerox Palo Alto Research Center, quoted

in “Japan Reaches Beyond Silicon, IEEE Spectrum, october

1985, p. 51.
.

Appendix A

Current Microelectronics Technology

This appendix provides general background information about microelectronics technology, the

roots of which extend back to the early part of this

century. Today, a vast assortment of integrated

circuits (ICs) and other miniature electronic devices are on the market. All of these components

pass through complex design and fabrication processes before reaching consumers.

Electronics Technology From Vacuum

Tubes to Integrated Circuits

Electronics technology over the last century has

advanced in a series of dramatic breakthroughs:

the vacuum tube, the transistor, and the integrated circuit. These are often used to designate

different generations of technology, as shown in

figure A-1.

The history of electronic devices began in the

early 1900s with the invention of vacuum tubes,

the first devices to reach major use in manipulating and amplifying electrical currents. This technology is limited by several related features.

Vacuum tubes require high voltages and, by

microelectronics standards, a great deal of power.

The invention of the transistor in 1947 marked

the beginning of a new generation in electronics.

The inventors fabricated the device from a crystal of semiconductor material to which they added

controlled quantities of different impurities. The

transistor had three points of electrical contact,

or terminals. Like a vacuum tube, it could amplify

an electrical signal, but at room temperature, and

it required only a small fraction of the power, voltage, and space that tubes demand. The transistor

rapidly became the central component in circuits

for a variety of applications.

By the late 1950s, transistor-based circuits dominated early computers and military systems. But

the drive for increasingly complex circuitry encountered some difficult barriers. Millions of connections were required to turn the hundreds of

thousands of components into a functioning

circuit—a labor-intensive process with unreliable

results. Further complicating things, the total circuit size was growing unmanageable, although the

individual components were quite small. The

equipment in which electronic devices were used

Figure A-1 .—Generations of Electronics Technology

Beyond

very large-scale

integration

t

Very

Early 1980s large-scale

integrated circuits

1958 Integrated

circuits

b

t

1947 Transistors

t

Early 1900s Vacuum

tubes

Fifth generation

Fourth generation

Third generation

Second generatio n

First generation

SOURCE Off Ice of Technology Assessment

demanded smaller, faster circuits that would consume less power and could be fabricated reliably.

The next major breakthrough in electronics was

the invention of the integrated circuit in 1958. Until this time, all electrical circuits consisted of separate components-transistors, diodes, resistors,

capacitors—connected by wires. The inventors of

the IC recognized that the wires and other com27
28

ponents could also be fabricated from or on the

same semiconductor material that was used to

make transistors.1 In this way, they made an entire circuit on a single piece, or chip, of the material. Using this technique, engineers were able to

make connections and components by etching the

semiconductor and depositing metals and insulators in patterns on the chip. The new process eliminated many of the problems associated with producing highly complex circuits. Because the huge

number of connections no longer had to be made

by soldering wires together, the IC technique was

more reliable and less labor-intensive. The individual components could now be smaller since they

would not need to be handled by people. This

shrinkage yielded circuits that operated at higher

frequencies and consumed less power.

Progress in microelectronics over the last 25

years has been based on further shrinkage of the

circuitry etched onto chips. The number of components per chip has, on average, almost doubled

every year, Today, up to 1 million transistors and

other components are fabricated on a single chip

that may have an area of less than 1 square centimeter.

Microelectronic Devices

In this background paper, the term “microelectronics” is used to refer to miniature electronic de-

‘For an account of the invention of the integrated circuit, see T. Il.

Reid, ‘The Chip,” Science 85, February 1985, p. 32, excerpted from T.R.

Reid, The Chip: 7’he Microelectronics Revolution and the Men W’ho

Made It (New York: Simon & Schuster, 1985).

vices in general. Figure A-2 shows the types of

microelectronic devices on the market today. The

most numerous and widely used of these are standard ICs made of silicon. Other semiconductor

devices, such as optoelectronic and microwave

products and discrete devices, are also part of

microelectronics technology. Additionally, a few

examples exist of miniature devices made from

materials other than semiconductors (e.g., magnetic bubble storage devices), but these fall outside the scope of this paper.

Types of Integrated Circuits

Integrated circuits are commonly classified in

a variety of ways and referred to with an impressive number of acronyms. They may be categorized by function, by the level of integration (number of components), by the type of transistors used

in the circuitry, or by the underlying material (or

substrate) on which they are fabricated.

Types of Functions.–Integrated circuits may be

either digital or analog (also called linear). In general, a digital circuit switches or stores voltages

that represent discrete values. For example, O

volts and 5 volts may represent the values O and

1, respectively. An analog circuit, in contrast, amplifies or otherwise modifies voltages of any value

within a given range (e.g., any voltage between O

and 5 volts). Some integrated circuits are designed

to convert signals from analog form to digital form

(A-to-D converters) or vice versa (D-to-A converters). Custom chips can combine the various

functions. Currently, the majority of ICs are digiFigure A-2.—Types of Microelectronic Products

Microelectronic products

.

1

1 I I

Integrated Discrete Optoelectronic Microwave

circuits transistors devices - devices

I

and diodes . b

t 1 ? * 1

I

Digital Analog Custom and other Lasers Monolithic

Ics (linear) ICs ICs Discrete and light- 4 4 < Detectors devices microwave

emitting ICs

t

diodes (LEDs)

-1 f

Microprocessors a Memories Logic-

ICs 4

A

Read-only Random-access

memories memories

(ROMs) (RAMs)

SOURCE Office of Technology Assessment
2 9

tal; computers, the major use of ICs, are based on

digital integrated circuits.

The major product categories in digital integrated circuits are logic circuits, memories, and

microprocessors. All three handle information in

the form of electrical signals: logic circuits process the signals, memories store them, and microprocessors combine the two functions.

Logic circuits carry out the operations required

to manipulate data in binary digital form. They

perform mathematical functions. Logic ICs are

typically classified according to the type of transistors used to make them.

Semiconductor memories are microelectronic circuits designed to store information. They fall into

two groups: read/write memories and read-only

memories (ROMs). Although both groups consist

primarily of memories that can be accessed randomly (i.e., any storage location can be accessed

in the same amount of time), the term “randomaccess memory” (RAM) usually refers only to

read/write memories. A computer can store a datum in a location within a read/write memory and

later retrieve it or store a new datum there. However, the computer can only retrieve information

that is already stored (by some external means) in

a ROM. Thus, a ROM may be used to store unchanging information or instructions that the computer needs regularly, while read/write memories

are used to store data as they come into the computer and as they are processed.

Read/write memories may be labeled “static” or

“dynamic” depending on the design of the circuits

that make up the RAM. Dynamic RAMs (DRAMs)

store data in the form of charge on capacitors,

and so require that the capacitors be recharged

regularly-every few milliseconds. Static RAMs

(SRAMs), on the other hand, store data by changing the state of transistors in the storage element,

a technique that requires a constant flow of power

rather than intermittent recharging to maintain

accurate storage. Both static and dynamic read/

write memories need a constant supply of power

to the circuit as a whole to operate.

Designers can program information into readonly memories in different ways. They may put the

information in the physical chip design; this type

is known as a mask-programmable ROM. Alternatively, chip manufacturers fabricate ROMs that

users can program themselves (programmable

ROMs, or PROMs)–a much more versatile product. Some varieties of these PROMS can be erased

and reprogrammed using light or electrical signals

(erasable PROMS, or EPROMs). EPROMs differ

from read/write memories in two ways: they typically cannot be reprogrammed by the computer itself, but they need no power source to retain information.

The capacity of a semiconductor memory is determined by the number of bits that it can store.

The maximum capacity available in the early

1970s was 1,024 bits, commonly called a kilobit or

kbit. Today, 262,144-bit (256 -kbit) RAMs are on

the market, and l,048,676-bit (l-megabit) RAMs

are just around the corner. Prices for memories

have dropped as dramatically as their capacity has

risen: memory costs approximately one-thousandth

of a cent per bit today.

Because a microprocessor is a complete computer processing unit on a single IC, it can process data expressed in a series of binary digits or

bits (ones or zeroes). The number of bits used in

the series determines the precision of the datum’s

digital representation; precision increases with the

number of bits. The original microprocessor, made

in 1970 at Intel Corp., was designed to handle four

bits. The industry introduced 8- and 16-bit microprocessors by the end of that decade and 32-bit

microprocessors within the last few years.

Levels of Integration.—The level of integration

of an integrated circuit refers to the number of

components packed on the chip. The progress in

integration since the invention of the IC is shown

in table A-1. Figure A-3 shows how a transistor

on an IC compares in size with some other microscopic items.

Types of Transistors. -An integrated circuit may

also be classified according to the kind of transisTable A-1 .—Levels of Integration

— ———

Design rule Number of Approximate

Level of integration (microns) transistors years

Scale-scale integration (SSI) . . . . ......... . . . ....30-20 2 to 64 1960-65

Medium-scale integration (MSI) ., . . . . ..20-10 64 to 2,000 1965-70

Large-scale integration (LSI) . . . . . . . . . 10-31⁄2 2,000 to 64,000 1970-78

Very large-scale integration (VLSI) . . ... 31⁄2 -1 1/4 64,000 to 2 million 1978-86

Ultra large-scale integration (ULSI) ... ... ... <1 l/4 >2 million after 1986

NOTE The numbers (n Ihls table a;e approximate NO standard de flnlt;on extsts for the dlfferenl I ntegratton levels

SOURCE Adapted from James M Early and Bruce E Deal Falrchlld Research Center and C Gordon Bell Encore Computer Co.[)
30

Figure A-3. —Microscopic Sizes

I&l ++ 1 micro n

Transistor on an

integrated circuit

approx. 1-2 microns

/ \

Bacterium

approx. 3 microns

long

Cross section of m

human hair

approx. 50 microns

1 Small

particle

15 microns

o 5 10 15 20 25 30 35 40 45 50 55 60 65 M icrons

SOURCE Off Ice of Technology Assessment Adapted fr)m .] flqure by Jlmmle R Suttle Army Research Of f!ce

tor used in its design. For silicon ICs, two types

of transistors are used: bipolar transistors and

metal-oxide-semiconductor field-effect transistors

(MOSFETs). These are further subdivided to describe the specific structure of the device and the

design of the surrounding circuit. The most common bipolar designations are ECL (emittercoupled logic) and TTL (transistor-transistor

logic); the most common types of MOSFETS are

NMOS (n-channel MOS) and CMOS (complementary MOS). (See the discussion of chip fabrication

in this appendix for some additional details.)

The primary differences between bipolar and

MOS technologies are speed (bipolar transistors

are faster); power (MOS circuits require less

power); and ease of manufacture (MOS circuits

have higher yield). Because the yield determines,

in large part, the cost of the chip, bipolar chips are

typically more expensive. However, the advantage

of higher speed is worth the extra cost and power

requirements for bipolar ICs in some applications.

For example, most makers of large computers use

bipolar ICs for the central components in their machines because they are the only chips capable of

the high speeds that are required. On the other

hand, personal computer vendors tend to base

their products on MOS chips, because cost is generally a bigger concern than speed.

Types of Materials.–Virtually all integrated circuits on the market today are made on substrates

of the same material that was the base for the first

IC: silicon. The longevity of silicon is due to its

physical properties as well as to practical economic

considerations. Silicon IC technology is more easily executed than is the technology of compound

semiconductors, which have more than one element, because the chemistry of a material made

of a single element is innately simpler. Furthermore, once silicon technology was established, economic factors dictated that any replacement be far

superior to silicon to be worth the large costs of

converting to a new system. And since silicon technology has never stopped progressing-or even

slowed significantly-attempts to replace it have

been shooting at a moving target. The recent decline of Josephson junction technology (which is
31

based on superconductors) for computers has

largely been attributed to this problem.

Despite its great usefulness, however, silicon

cannot satisfy all demands of microelectronics.

Since transistors made from gallium arsenide

(GaAs) can be faster and more impervious to radiation damage than silicon transistors, several

companies are trying to introduce GaAs integrated circuits. These ICs are particularly attractive for some military applications (e.g., spacebased circuitry), and they may also find standard

commercial applications. However, they cannot

currently compete with silicon technology for

standard functions. For example, a fully operational 1,024-bit GaAs RAM is still in the laboratory phase, while silicon RAMs with over 250

times the capacity have been on the market for

some time already, (See ch, 3 for a more detailed

description of current R&D activities in this area.)

Other Semiconductor Devices

Semiconductor materials are also used to make

a host of individual microelectronic devices, as

distinguished from standard silicon integrated

circuits. These include discrete transistors and

diodes, optoelectronic devices, and microwave

devices.

Discrete Transistors and Diodes.—Electronic instruments, including radios, televisions, and control instruments, use not only ICs but also individual transistors and diodes. (Diodes are twoterminal devices that allow current flow in only one

direction.) These components are typically made

from silicon, The transistors may be bipolar or

field-effect transistors.

Optoelectronic Devices. -Semiconductors such as

gallium arsenide (GaAs), iridium phosphide (InP),

cadmium telluride (CdTe), and mercury telluride

(HgTe) are the bases for a range of other microelectronic devices that require properties that silicon lacks—the ability to interact efficiently with

light and the ability to operate at extremely high

speeds or frequencies.

Optoelectronic devices depend on the first of

these properties. Optoelectronics includes lightemitting diodes (LEDs) and lasers, which convert

electrical signals to light signals, and photodetectors, which convert light signals into electrical signals. The two major applications for these devices

are fiber optic communications and long-wavelength infrared light detection.

Fiber optic or lightwave communications systems use glass fibers to transmit light signals from

one point to another; the fibers can replace metal

wires that carry electrical signals. Semiconductor

lasers or LEDs generate the light signals, and semiconductor photodetectors convert the received

light signals back to electrical signals. These devices are most commonly made from layers of

GaAs and aluminum gallium arsenide (AIGaAs) on

a substrate of GaAs, or, more recently, from layers

of iridium gallium arsenide phosphide (InGaAsP)

and iridium gallium arsenide (InGaAs) on a substrate of InP. The quaternary materials-different

compositions of InGaAsP-can generate and detect the wavelengths of light that travel along the

glass fibers with the least distortion (wavelength

of 1.3 microns) and fading (wavelength of 1.55

microns).

The primary purpose of long-wavelength infrared (IR) detection is to “see” living or hot objects in the dark. The Department of Defense has

spearheaded work on IR sensors, since their potential military uses are many. Typically, the devices are made from alloys of HgTe and CdTe, because these materials can be adjusted to detect the

appropriate wavelengths of light (3 to 5 microns

and 8 to 14 microns). Special types of silicon diodes can also act as IR sensors in some of these

wavelength ranges.

Microwave Devices.-Microwave (high-frequency) devices take advantage of the intrinsic high

speed of gallium arsenide. They generate, amplify,

switch, and receive microwave signals with frequencies from approximately 1 to 60 gigahertz (1

gigahertz is 1 billion cycles per second). Radar systems and transmission systems for telephone, television, and telegraph signals, which operate at

these frequencies, as well as military systems, depend on these microwave devices. This technology

is at present progressing to monolithic microwave

integrated circuits (MM ICs), in which microwave

circuits are fabricated on a single substrate, typically gallium arsenide.

Technologies To Produce

Semiconductor Microelectronics

Numerous steps are involved in making any

microelectronic device. Integrated circuits are the

most complex in this respect. The process can be

separated into two parts: circuit design and chip

fabrication.

Circuit Design

Once the application for a new integrated circuit

is established, the first step in making the chip is

the design of the circuit. The use of a wide variety
32

of computer-aided design (CAD) tools has facilitated all parts of the design process for large ICs

tremendously. For a digital IC, the overall circuit

will typically be a combination of logic functions

and storage functions. The designer determines

the layout of the subcircuits that carry out each

of these functions and the connections between the

subcircuits. Also in this initial stage, the chip

designer must establish mechanisms for bringing

the external signals and power to the various subcircuits. Each subcircuit may itself be composed

of smaller, interconnected cells of circuitry. The

fundamental units for the designer are the individual components, such as transistors, diodes,

resistors, and capacitors, and the connections between them.

Because the process of designing circuits has

grown so complex over the years, now involving

over 100,000 components on a chip, design software is a major research area which is as important to progress in microelectronics technology as

advancements in chip fabrication. As the capabilities of design tools grow, they provide increasingly greater flexibility for different chip architectures, and therefore open the door to using IC

technology in completely new ways to fabricate

specialized circuits.

Chip Fabrication

Chip fabrication includes making the circuitry

and packaging the completed chip.

The first step of the process is transferring the

circuit designers’ layout onto the semiconductor

chip. The substrate onto which the circuits are

transferred is a wafer, or thin slice, of a single crystal of the semiconductor. Currently, a typical wafer is several inches in diameter, so many chips can

be made on a single wafer and separated after circuit fabrication. The circuit is created by depositing thin layers of metals, insulators, and perhaps

additional semiconductor materials on the wafer;

adding n-type impurity atoms (negative charge

contributors) or p-type impurity atoms (positive

charge contributors) to the semiconductor; and

etching away precisely defined portions of the various layers with chemicals or ions.

Illustrating a simplified example of one part of

this process, figure A-4 shows the steps in the first

phase of the fabrication of a single transistor-an

n-channel MOSFET—on a silicon substrate. The

objective of this first phase is to add p-type impurity atoms in two small selected regions near the

surface of the chip, thereby forming “p-wells.” The

first six steps of this phase (which constitute liFigure A-4.– First of Four Mask Processes To Make

an N-channel MOSFET

n-type I I

n-type

A. B

siIicon silicon I

Light

E

I

n-type

I

F

I

n-type

silicon silicon I

p-,type impurities

I I I I

Metal contacts

SOURCE Office of Technology Assessment

thography) leave a layer of silicon dioxide (SiO2),

with small holes etched in it, on top of the substrate. This layer serves as a stencil for the p-type

impurities to which the chip is then exposed: only

the portions that are not covered with SiO2 become

p-type.

This process is accomplished as follows. The

starting material is a wafer of silicon to which ntype impurities were added during growth. The

first step is to grow a thin layer of silicon dioxide

on the surface of this substrate, either by exposing the surface to the proper chemicals, or by heating the wafer in a furnace with water vapor (step

A in figure A-4). Next, a layer of light-sensitive material called photoresist coats the oxide (step B).

The portions of the photoresist that are exposed
—

when the surface is irradiated with light through

a glass mask (step C) undergo a chemical change.

These parts of the photoresist do not wash away

when the chip is rinsed in the chemical developer,

but the unexposed portions do (step D). Now, the

chip is placed in a bath of chemicals that etch away

silicon dioxide, but leave the photoresist and silicon intact (step E). Since the portions of the oxide that are below the photoresist are not etched,

this procedure opens windows in the oxide layer.

A different chemical bath removes the remaining

photoresist without damaging the oxide regions

(step F). The chip is now ready for exposure to the

p-type impurities, which are driven into the chip

either from a piece of source material in a furnace

or by accelerating impurity ions into the material

(step G). When the number of p-type impurities exceeds the number of n-type impurities that were

there originally, the wells will exhibit p-type behavior. Finally, when the p-wells have been formed,

the remaining SiO2 can be chemically removed

(step H).

After three more mask cycles, the completed device is composed of regions of semiconductor with

p- and n-type impurities; silicon dioxide, which acts

as an electrical insulator; and aluminum electrical

contacts. In present-day chips, the physical separation between the regions with p-type impurities

may be less than 1 micron, and the entire transistor is invisible to the naked eye. Furthermore, the

number of impurities must be controlled to within

a few parts per billion in some regions of the

device.

Fabricating an entire integrated circuit is significantly more complicated because a larger number of much more complex masks are necessary.

Chips now also require extremely sophisticated

techniques for selective etching of materials, photoresist exposure, and other parts of the process.

All of these processing steps must be carried out

in an environment completely free of particulate

—clean-room facilities. Thus, it is not surprising

that the trend in chip fabrication has consistently

been towards greater automation of the processes,

which reduces the chances of contamination or human error. Today, most machines used in chip

fabrication can handle cassettes containing many

large wafers of silicon, minimizing the need for humans to handle the delicate circuitry.

When the final lithographic procedures are complete, the large silicon wafer is tested and diced

to separate the individual chips. The good chips

are then assembled in packages appropriate for

their particular applications. Packaging technology is a crucial part of the production of ICs.

Proper packaging techniques can shield the chip

from physical damage and some forms of radiation

damage, For commodity ICs that are sold to a variety of end users, standard packaging systems are

necessary to ensure that chips are interchangeable.

On the other hand, chips designed and used for

high-speed computation require special custom

packages that maximize the speed with which signals enter and leave the chip, since standard packaging schemes could obliterate the special speed

advantage of the chip by itself.
Appendix B

Glossary of Terms

Chip: A small piece (typically less than 1 square

centimeter) of a semiconductor wafer. Also used

to refer to a packaged integrated circuit.

Compound semiconductor: “A semiconductor made

of a compound of two or more elements instead

of a single element like silicon, II I-V semiconductors are made from elements in group 111 of

the periodic table (such as aluminum, gallium,

and iridium) and group V of the periodic table

(such as nitrogen, phosphorus, arsenic, and antimony). Binary compounds are made with two

elements, ternaries with three elements, and

quaternaries with four elements. ”

Custom and semicustom integrated circuits: ICs that

can be designed to varying degrees by the end

user for a specific application. Full custom ICs

are designed and fabricated from scratch: semicustom chips allow the user to modify a chip for

the application.

Design rule: Minimum feature size. Current chips

typically employ design rules of 1 micron or

greater. See table A-1 in app. A.

Diode: A two-terminal electronic device that allows

current to flow freely in one direction only.

Gallium arsenide (GaAs): A compound semiconductor with properties necessary for very high-frequency microwave (analog) devices and optoelectronics. There are also several efforts to

make high-speed digital ICs based on gallium

arsenide.

Integrated circuit (IC): Electronic circuits, including transistors, resistors, capacitors, and their

interconnections, fabricated on a single small

piece of semiconductor material (chip). Categories of ICs such as LSI and VLSI refer to the

level of integration, which denotes the number

of transistors on a chip. ICs may be digital (logic

chips, memory chips, or microprocessors) or

analog. The transistors that ICs are made of

p

may be bipolar transistors, or one of a variety

of metal-oxide-semiconductor (M OS) transistors.

Logic chips: ICs that manipulate digital data. See

app. A.

LSI: Large-scale integration. See table A-1 in app.

A.

Memory chips: Devices for storing information in

the form of electronic signals. See app. A.

Microprocessor: A computer central processing

unit on a single chip. See app. A.

Micron: One-millionth of a meter. See fig. A-3 in

app. A.

Microwave circuit: An analog circuit designed to

process high-frequency signals. See app. A and

ch. 3.

MMIC: Monolithic microwave integrated circuit.

See app. A and ch. 3.

Optoelectronic devices: Devices that convert light

signals to electronic signals and vice versa. See

app. A and ch. 3.

RAM: Random-access memory. See app. A.

ROM: Read-only memory. See app. A.

Semiconductor: A crystalline material whose electrical conductivity falls between that of a metal

and that of an insulator. Semiconductor materials are used to fabricate virtually all microelectronic devices. Silicon is the most common;

others include germanium, gallium arsenide

(GaAs), indium phosphide (InP), mercury telluride (HgTe), cadmium telluride (CdTe), and alloys of these compound semiconductors. See fig.

1 in ch. 3 for a periodic table of the elements

showing common elements used in semiconductors.

Substrate: A piece of material, typically a semiconductor, on which layers of materials are deposited and etched to fabricate a device or a circuit.

Transistor: A three-terminal electronic device that

can be used to switch or amplify electronic

signals.

VLSI: Very large-scale integration. See table A-1

in app. A.

35