i- U.S. DEPARTMENT OF COMMERCE 4,ierna! Tac"iqrO!Information Service AD-A035 149 BASIC LIMITATIONS IN MICROCIRCUIT FABRICATION TECHNOLOGY RAND CORPORATION SANTA MONICA, CALIFORNIA NOVEMBER 1976 ARPA ORDER NO.: 189-1 7Pi0 Information Processing R-1956-ARPA o November 1976 Basic Limitations in Microcircuit Fabrication Technology Ivan E.Sutherland, Carver A. Mead, and Thomas E.Everhart - REIDUtCED• ? NATIONAL TECHNICAL INFORMATION SERVICE U. S. DEPARTMENT OF COMMERCE SPRINGFIELD, VA. 22161 A Report prepared for DEFENSE ADVANCED RESEARCH PROJECTS AGENCY DiFF9 19tg" au URandl DISTRIBTION STATEK,,T A AppTovod fot publc zelo Distdbution Unlli~d NATIONAL SECURITY INFORMATION Unauthorized Disclosure Subject to Criminal Sanctions. The research described in this report was sponsored by the Defense Advanced Research Projects Agency under Contract No. DAHC15-73-C-01 81. Reports of The Rand Corporation do not necessarily reflect the opinions or policies of the sponsors of Rand research. Ut4CLA~sSI FI ED- Data Entered) SECURITY CLASSIFICATIONS....READ OF THIS PAGE (Wheni rNSTRUCTIONS REPORT DOCUMENTATION PAGE BEFORE COMPLETING FORM NO. 3. RECIPIENT'S CATALOG NUMBER I. REPORT NUMBER 2. GoVT ACCESSION R-1 %6-ARPA i4. TITLE food Subtitle) S. TYPE OF REPORT & PERIOD COVERED Interim Basic Limitations in Microcircuit Fabrication Technology 6. PERFORMING ORG. REPORT NUMBER 8. CONTRACT OR GRANT NUMBER(@) 7. AUTHOR(a) DAHC15-73-C-0181 I. E. Sutherland, C. A. Mead, T. E. Everhart ELEMENT. PROJECT. TASK 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM The Rand Corporatinn. AREA & WORK UNIT NUMBERS 1700 Main Street Santa Monica, CA 90406 12. REPORT DATE 11. CONTROLLING OFFICE NAME AND ADDRESS Defense Advanced Research Projects Agency November 1976 Department of Defense IS. NUMBER or PAGES Arlington, VA 22209 47 Office) 15. SECURITY CLASS. (of this report) 14. MONITORING AGENCY NAME & ADDRESS( diflerent from Controlln8 Unclacsified IS*. DECL ASSI FICATION/ DOWNGRADING SCHEDULE t6. DISTRIBUTION STATEMENT (of this Report) Approved for Public Release; Dictribution Unlimited from Report) 17. DISTRIBUTION STATEMENT (o. the abstract entered In Block 20. If differont No restrictions IS. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue an reverse side it necessery and Identity by block number) Avrn;;lu.. Microel ectronics NTIS "III SUM Molecular Electronics DOC hif"SO Circuits UoAMcN0CE 11 Research Management JUSTIFICAIN ....... 20. ABSTRACT (Continue an rvereesrdle if necessary and Identify by block nmeber) CMm IDISTA11UTJOI/AINLUaILj1-ist ,ýsee reverse side 7 j ,. *i-.mut DD , 1473 EDIOP OF INOV65 ISOBSOLETE UNCLASSIFIED Ie SECURITY CLASSIFICATION OF THIS PAGE (P1Mm Dots Entered) UNCLASSI FI ED SECUI-TY CLASSIFICATION OY THIS PAUCffw Dog* Xl14m__ \Thft report discusses some high-leverage research at-eai 'n microcircuit fabrication, not now receiving government or private support, where relatively small, advanced research efforts may have substantial payoff. Eased on the fact that microcircuit fabrication has reached or almost reached limitations in both size and precision, the study focuses on a number of areas where progress can be made, identifying those ade- quately covered by existing programs and highlighting those where relatively little work is being done. The authors recommend four important research efforts aimed at: (1) m-king small devices; (2) measuring the limits of dimensional stability of silicon substrates and mask materials; (3) predicting the optimum feature size, die size, and wafer size, given the constraints of the newly evolving technology; (4) understanding the system design implications of very-large-scale integrated circuits. "The potential for future capability is truly impressive," say the authors, who believe that the integrated circuit revolution has run only half its course and that a change in microcircuit complexity of four more orders of magnitude is highly probable. Biblio. (DGS) UNCLASSIFIED .=: ARPA ORDER NO.: 189-1 7P10 Information Processing R-1956-ARPA November 1976 Basic Limitations in Microcircuit Fabrication Technology Ivan E. Sutherland, Carver A. Mead, and Thomas E. Everhart A Report prepared foi DEFENSE ADVANCED RESEARCH PROJECTS AGiENCY Randi SANTA MONKCA, CA. 900A APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED IIll II' _ _ -iiM- PREFACE This report present- the findings of a 6-month study undertaken for the Defense Advanced Research Projects Agency to ascertain what, if any, research ARPA might sensibly conduct in integrated microcircuit technology. The authors entered upon the study through a conviction that serious international competition in this technology may appear in the next few years, and a desire to ensure for the United States as iavorable an opportunity to meet this competition as research can make available. Both the ubiquitous nature of micro-electronics in defense applications and the particularly severe special defense requirements for complex, low-power, micro-miniaturized circuitry make a commanding lead in this technology very important. The authors wished to assure themselves and ARPA that the existing research programs provide ade- quately for the forthcoming needs of the nation. The report details some high-leverage research areas, not now receiving government or private support, where relatively small, advanced research efforts may have substantial. payoff. No endorsement of the study conclusions by ARPA is implied or intended. During the course of the study, the authors visited major labora- tories having a capability for making very small circuitry. In nearly every visit, discussions with the research personnel were complete and frank. The authors believe that they have seen all the major U.S. activities aimed at producing circuits cf submicron dimensions. It was quickly realized that U.S. industry is treating the new developments in microcircuit technology as a continuation of the coupled ovolution of decreasing size of circuit features and increasing com- upleity of logical units that has been so effective in the past. The authors therefore asked each industrial group specific questions about its aspirations for very-small-size circuits of modest complexity. The responses were disappointingly conservative. There is such a wide variety of problems to be overcome in developing a submicron circuit technology, and those experienced in the field have seen so many "rocks in the road," that relatively Rlow progress is the most that they can foresee. Moreover, the only developments economically justifiable for private support must maintain as high a level of complexity as posdible. The authors, as a group, believe that a more direct push toward very small circuitry, albeit of modest complexity, will pay off handsomely. The three authors of this report bring a wide range of experience to bear oni thi study. Carver Mead, Professor of Electrical Engineering at the California Institute of Technology, is an expert in seniconduc- tor physics; he has contributed importantly to an understanding of the fundamental physical principleek that limit how small semiconductor cir- cuitry can be made. Thomas Everhart, Chairman of the Depai-tmnenr of Electrical Engineering and Computer Sciences at the University of Call.- fornia at Berkeley, is an expert in electron microscopy; he was one of the earliest builders of fine-res" .ution electron beam sywtems. Ivan Sutherland, a member of the Rand staff when this report was prepared and now Professor of Computer Science, California InstL:ute of Tech- nology, is an expert in systems design; he has done muc.h fundamental work in large systems for computer graphics. Together they have sought to understand what limitations to microcircuit fabricat 4 on are funda- mental. They hive tried to "orthogonalize" the tasks in order to de- termine separate areas where progress can be made, Identifying those areas adequately covered by existing deve.opment programs and high- lighting those where relatively little work is being done. The potential for future capability revealed by this study is truly impressive. There is every reason to believe that the integrated circuit revolution has run only half its course; the change in complexity of four to five orders vf magnitude that has taken place during the past 15 years appears to he only the first half of a potential eight-order- of-magnitude development. There seem to be no fundamental obstacles to 107 to 108 device integrated circuits. The authors hope that their efforts may contribute to having such crcuits sooner than would other- wise be the case. Finally, the authors are indebted to the foresights of Rand's sponsors in ARPA, to the cooperation of the many technical experts in industry who gave so generously of their time and knowledge, and to the many people at Rand and at Scien(e Applications, Inc. without whose neil, their efforts would not have borne fruit. SU3OARY AMID RCOMUNDATIONS Today's microcircuit fabrication industry is operating against two fundaumntal limits: the wavelength of visible 1lght and the number of elements that can be reproduced witth a single alignmient. The use of electron beams, ultraviolet light, and X-rays makes fabrication of submicron geometry devices possi:,i. Or. the other haed, because no significant improvements in the number of devices reproduced per slign- ,ent ere anticipated, substantial changes in the patterning processes are likely. In spite of the revolutionary nature of the changes in fabrication and design vnethods imposed by subml(cron geometries, U.S. itdustry ap- pears