From Bell Labs to Silicon Valley: a Saga of Semiconductor Technology Transfer, 1955-61*

From Bell Labs to Silicon Valley: A Saga of Semiconductor Technology Transfer, 1955-61*

by Michael Riordan

espite the fact that the Bell Telephone Laboratories had Doriginated almost all the silicon technology eventually used to invent the integrated circuit, or microchip, this revolutionary breakthrough occurred elsewhere—at Texas Instruments, Inc., in Dallas, and Fairchild Semiconductor Corporation in Mountain View, California. In the latter case, the transfer of this technology occurred largely through the offices of a pivotal but ultimately unsuccessful company, Shockley Semiconductor Laboratory, which had been formed by transistor pioneer William Shockley. After leaving Bell Labs in 1955, he brought together a stellar team of scientists and engineers who later departed (in September 1957) to found Fairchild, Fig. 1. Shockley Semiconductor Laboratory at 391 San Antonio Road in Mountain View, bringing a deep understanding of the California, as it appeared in 1960 after Clevite Corporation had purchased it and diffused-silicon technologies they had renamed it Shockley Transistor Company. (Courtesy of Kurt Hübner) learned while employed by Shockley. One pivotal contribution to silicon proved satisfying. So by early 1955 of automatic means for production of technology, however, originated entirely Shockley was seeking to get back into diffused-base transistors.”3 at Fairchild—the planar manufacturing industrial research—this time as the His original plan was to lure away process invented and developed by head of his own company.1 some of his most accomplished Bell the physicist Jean Hoerni. This crucial In March 1955 his sense of urgency Labs colleagues, such as Tanenbaum technique, in which an oxide layer on in these efforts was stimulated by news and Morgan Sparks, who had fabricated the silicon surface is used to protect from Bell Labs. Not only had chemist the first junction transistors. But one the sensitive p-n junctions beneath it, Henry Theurer finally produced by one they turned him down that fall, has served ever since 1961 as the basis silicon with impurity levels of less claiming their families were too deeply of microchip fabrication. And Hoerni’s than a part per billion using float-zone rooted in New Jersey and they could conception of this method occurred refining. But Morris Tanenbaum and not bear to leave Bell Labs. Thus he substantially earlier than most historical D. E. Thomas had also succeeded in subsequently criss-crossed the United accounts have thus far reported. forming the first diffused-base (and States, trying to recruit the best possible In this article, I try to set the record emitter) silicon transistor using samples scientists and engineers for Shockley straight by recounting the important provided by Calvin Fuller (see article Semiconductor Laboratory. And he hired steps and major influences that brought by Nick Holonyak on p. 30). “Morrie some top-notch ones, too: physicists silicon technology to California—in Tann has AlSb plus Al bonded,” reads Hoerni from Caltech, Jay Last from the process laying the technological a cryptic note in Shockley’s pocket MIT, and Robert Noyce from Philco—as foundations of Silicon Valley. notebook dated 23 March 1955, while well as physical chemist Gordon Moore he was still at the Pentagon, referring from the Johns Hopkins Applied Physics Silicon Technology Heads West to micrometers-thin aluminum and Laboratory. Among the eldest of this antimony impurity layers diffused into group at age 28, Noyce was about the By 1954 William Shockley was the silicon.2 only one with extensive semiconductor becoming increasingly frustrated by Over the next few months, Shockley experience, having developed high- his lack of professional advancement at began talking with executives at RCA, frequency germanium transistors at Bell Labs. Although head of transistor Raytheon, Texas Instruments and Philco.4 research, he had been passed over for elsewhere about the possibility of Only Noyce among them had higher positions and seemed mired starting a firm expressly devoted to attended the third Bell Labs symposium at this middle-management level producing diffused-silicon devices. For on transistor technology in January despite his many publications and most of that summer, he met with 1956, devoted to the advanced patents, including the all-important only passing interest until he spoke silicon technologies just then being ones on the junction transistor. Thus with his friend and fellow Caltech developed—especially diffusion. But he began casting around for other alumnus Arnold Beckman, founder and because Beckman had licensed the rights possible positions, taking a leave of president of Beckman Industries, Inc. In to the transistor patents from Bell’s absence to serve as a visiting professor early September they met in Newport parent company, AT&T, Shockley and his at Caltech and as a military advisor Beach, California, and agreed to found new employees had ready access to the in the Pentagon’s Weapons Systems a new division led by Shockley whose information presented there, including Evaluation Group. But neither option purposes included “the development early preprints of the papers that

* Adapted in part from Crystal Fire: The Birth of the Information Age, by Michael Riordan and Lillian Hoddeson, W. W. Norton & Co., New York (1997), esp. pp. 225-275. See also M. Riordan and L. Hoddeson, “The Moses of Silicon Valley,” Physics Today, pp. 42-47 (December 1997).

36 The Electrochemical Society Interface • Fall 2007 to focus the company’s talents and energies on devices that were then at the frontiers of semiconductor technology, such as field-effect transistors and the four-layer p-n-p-n diode, often called the Shockley diode because he held a patent on it. At a given potential called the breakdown voltage, current would suddenly begin to flow through the two-terminal device, switching it from “off” to “on.” A remarkably simple, compact semiconductor switch, it was the ultimate realization of a goal that had been subtly implanted in Shockley’s mind at Bell Labs two decades earlier.10 Although a brilliant conception, however, the four-layer diode was extremely difficult to fabricate with uniformity and reliability. Workers had to polish a silicon wafer to have exactingly parallel planes on its Fig. 2. Senior staff of Shockley Semiconductor Laboratory toast their illustrious leader two sides and then carefully diffuse William Shockley (seated at head of table) at a celebratory luncheon on 2 November impurities into the wafer from 1956, the day after the announcement of his Nobel Prize. Seated at left is Gordon Moore both sides simultaneously. Lack of and right of him is Sheldon Roberts. Robert Noyce stands in the middle and Jay Last is enough precision meant the diffused at far right, both lifting glasses. (Courtesy of Intel Corporation) impurities would penetrate to irregular, unpredictable depths, leading to would be published in 1958 as the final on this important method. The preprint variations in the breakdown voltage and other electrical characteristics.11 volume in the classic series, Transistor also contained crucial new information Noyce, Moore, and others thought Technology, which was becoming known about how to etch tiny openings in throughout the semiconductor industry that layer and to use the remaining that this diode was much too difficult as “Ma Bell’s cookbook.”5 Shockley oxide as a mask against the diffusion a project for the young company to could also call upon his old colleagues of trace impurities into the silicon. attempt at such an early stage in its Sparks, Tanenbaum, and Jack Morton, That technique would allow workers to evolution. We should concentrate head of device development, to visit the establish intricate patterns of n-type new California company and consult and p-type material in the silicon. with his charges in their converted Shockley circulated this document Quonset hut at 391 San Antonio among his technical staff (Fig. Road (Fig. 1). They spent most of that 3), giving them all a crucial early first year purchasing or building the glimpse of what would become one necessary equipment, such as silicon of the core enabling technologies crystal growers and diffusion furnaces, for silicon integrated circuits and and learning how to use it in making ultimately lead to the emergence of semiconductor devices. Silicon Valley.7 By the time Frosch On 1 November 1956, marvelous and Derick’s paper was published news reached the Mountain View firm in the Journal of The Electrochemical that Shockley had won the 1956 Nobel Society the following September, Prize in physics for the invention of the Shockley and his staff were already transistor, shared with John Bardeen developing ways to implement this and Walter Brattain. The next day they disruptive new technology.8 stopped working before noon for a celebratory luncheon at nearby Rickey’s A Rebellion Erupts Studio Inn in Palo Alto. A photograph of that gathering (Fig. 2), with Shockley But all was not well at the at the head of the table being toasted by Mountain View laboratory. By Noyce, Moore, Last, and others around 1957, members of the technical him, has achieved iconic status in the 6 staff had begun to resent Shockley’s lore of Silicon Valley. often heavy-handed management Upon returning from Stockholm style and his quirky selection of in mid-December, Shockley found a R&D projects. After a couple of package in his mail from the patent worrisome incidents, he started licensing engineer at Western Electric investigating the backgrounds Company, AT&T’s manufacturing arm. of a few of his employees. And It contained a preprint of an article by he gave one of them a vicious, Carl Frosch and Lincoln Derick titled embarrassing tongue-lashing that “Surface Protection and Surface Masking many others overheard. Several of during Diffusion in Silicon.” Frosch the early employees were extremely Fig. 3. Copy of the 14 December 1956 letter to Shockley had delivered a paper on diffusion in 9 dissatisfied and ready to quit. from the Western Electric patent engineer that the third transistor symposium, but For reasons about which we can accompanied a preprint of Frosch and Derick’s paper on it did not contain much information only guess, Shockley had lost interest oxide masking, plus the initialed routing list of technical about use of a silicon-dioxide layer to in the original goal set for the staff members of Shockley Semiconductor Laboratory passivate the silicon surface because firm—manufacturing diffused- who read this paper. (Stanford University Archives) Bell Labs was still applying for a patent base transistors. He instead began

The Electrochemical Society Interface • Fall 2007 37 Riordan had learned and developed at Shockley staff members remaining at Shockley (continued from previous page) Semiconductor. Roberts grew silicon Semiconductor Laboratory were still crystals while Moore tackled issues of struggling to make four-layer diodes. first on three-layer devices such as the diffusing impurities into them. Last and diffused-base transistor, they argued, and Noyce took on the intricate tasks involved The Planar Manufacturing get a product out the door. After that they in oxide masking and photolithography, could begin attempting the more difficult developing a “step-and-repeat” camera to Process problem of fabricating the four-layer aid them in defining tiny, precise n-type But a serious problem emerged with diode. But Shockley was not listening and and p-type areas in the silicon wafers.16 these mesa transistors that threatened began devoting more and more of the By May 1958 the group had the continued success of the fledgling company’s resources to this pet project. successfully fabricated prototype n-p-n company. Some of these devices He eventually set up a separate R&D silicon transistors, based on the “mesa” experienced catastrophic failures that group working mostly in secret on the structure pioneered by Tanenbaum and were traced to bits of foreign material four-layer diode, which further angered Thomas at Bell Labs.17 In such a structure, being dislodged and becoming attached technical staff members left out of the a thin p-type base layer and an n-type to the exposed junctions, attracted loop. emitter layer were diffused into an n-type by strong electric fields there. Merely The conflict reached the boiling point silicon wafer that formed the collector tapping on the metal cans housing in mid-May 1957, when Beckman came of this bipolar junction transistor. Oxide these transistors with a pencil eraser was up for a meeting to discuss the division’s masking and photolithography were used often sufficient to trigger such failures. problems and plans. Taking umbrage at his partner’s proposals and request to control expenses, however, Shockley stood up and stomped out of the room, shouting, “If you don’t like what we’re doing here, I can take this group and get support any place else!”12 But nobody left the room except Shockley. His outburst triggered a four- month sequence of events that led in September to the departure of eight of his top lieutenants—including Hoerni, Last, Moore, and Noyce. A pivotal moment in the history of the semiconductor industry, it is briefly recorded in yet another Shockley notebook: “Wed 18 Sep—Group resigns.”13 A Successful Semiconductor Company Within days the group of eight rebels—which also included the metallurgist Sheldon Roberts and engineers Julius Blank, Victor Grinich, and Eugene Kleiner—signed a $1.38 million agreement brokered by the investment- banking firm Hayden Stone with Fairchild Camera and Instrument Corporation of Fig. 4. Official photograph (circa 1960) of the eight Fairchild founders, who later became famous in Silicon Valley lore as the “Fairchild Eight.” Left to right, Gordon Moore, Syosset, New York, on Long Island (Fig. Sheldon Roberts, Eugene Kleiner, Robert Noyce, Victor Grinich, Julius Blank, Jean 4). Using these start-up funds, the eight Hoerni, and Jay Last. (Wayne Miller photograph courtesy of Fairchild Semiconductor began setting up a new firm known as Corp. and Magnum Photos) the Fairchild Semiconductor Corporation just over a mile away on Charleston Street in Palo Alto.14 At almost exactly the same moment, to define these regions. But after attaching This was a fundamental design flaw of Frosch and Derick’s revolutionary paper the electrical leads, workers etched away the exposed mesa structure. A possible was published in the September 1957 issue any remaining portions of the silicon- solution being considered was to try to of the Journal of The Electrochemical Society. dioxide sheath, exposing the underlying leave the oxide layer in place over the But because they had read the preprint of junctions. This was standard practice in junctions—or deliberately form one there this paper while working at Shockley Lab, the semiconductor industry at the time, in order to protect them during the final the Fairchild upstarts had a big head start for the oxide layer was widely viewed as processing steps.19 on most of the competition. According to “dirty”—especially at Bell Labs. A far more elegant approach was put Roberts, some of them—including Hoerni, Fairchild’s transistors were the first forth by Jean Hoerni, who had been Moore, and Noyce—had already begun commercially successful mesa transistors, leading Fairchild’s efforts to fabricate p-n- experimenting with double diffusion and beating out Texas Instruments, which p transistors to satisfy IBM’s specifications. oxide masking while they were there.15 was also working on similar devices. A theoretical physicist by training, The first commercial product Not only did they meet IBM’s stringent Swiss-born Hoerni had earned advanced attempted by Fairchild was a high- specifications, but they also began to degrees from the Universities of Geneva frequency, diffused-base silicon tran- be used in other avionics applications. and Cambridge, and often worked on sistor to drive core memory in an onboard Fairchild Semiconductor recorded sales his own. At Shockley Lab he at first computer that IBM was making for the of over $500,000 —almost all of it had an office separate from the Quonset guidance-and-control system of the B-70 coming from this product—in 1958, its hut, where he could go off by himself bomber. The eight partners began first full year of operations, and ended the to calculate diffusion curves and other applying the silicon technology they year in the black.18 Meanwhile, the loyal useful theoretical quantities.20

38 The Electrochemical Society Interface • Fall 2007 Fig. 5. Cross-sectional drawings of mesa and planar transistors, copied from Jean Hoerni’s 1961 publication, “Planar Silicon Transistors and Diodes,” Fairchild Semiconductor Corp. Report No. TP-14. (Stanford University Archives)

While the Fairchild founders were called this planar process “the most the failure-prone mesas (Fig. 5). What’s busy setting up offices and equipment important innovation in the history of more, he soon showed they had far on Charleston Street, Hoerni had the semiconductor industry.”23 superior electrical characteristics—with already begun to consider a new and When Hoerni conceived this higher gains, and leakage currents different way to fabricate transistors. approach in December 1957, Fairchild often less than a nanoampere. As An admitted contrarian, he suggested lacked the technical abilities needed Hoerni concluded in a paper that he that instead of etching away the to implement it. And the new firm’s presented at an October 1960 meeting oxide layer at the end of processing, talents and energies had to be devoted on electron devices in Washington, DC, it instead be left in place to protect the almost entirely to getting its first mesa “the planar design offers considerable sensitive junctions. He entered this transistors out the door. But once the improvement and stabilization of the revolutionary new idea on pages 3 and techniques of diffusion, oxide masking parameters most likely to suffer from 4 of his crisp new lab notebook on and photolithography had been surface contamination.”24 1 December 1957, hardly more than mastered in 1958, he returned to his On 14 January 1959, Hoerni had two months after the firm had been conception as a way to address their had a Fairchild secretary type up a founded!21 reliability problems. With the help of formal patent disclosure to give the Titled “Method of protecting Last, who made the extra mask he company’s attorney. Apart from a few exposed p-n junctions at the surface needed, Hoerni proved out this idea in typographical changes and improved of silicon transistors by oxide masking March 1959, fabricating prototype planar drawings, it is completely identical to techniques,” it was witnessed that transistors that avoided the problems of the 1 December 1957 entry in his lab same day by Noyce. The very first notebook—indicating the great paragraph is revealing: accuracy of his original theoretical The general idea underlying insight.25 Just a few months later this invention is the building Moore and Noyce, who had by then up of an oxide layer prior to emerged as the natural leaders of diffusion of dopant atoms the new firm, decided to reorient at the places on the surface Fairchild’s transistor production of the transistor at which p- lines to this promising new planar n junctions are expected to approach.26 emerge from the body of the semiconductor. The oxide layer The Monolithic Idea so obtained is an integrant (sic) part of the device and will Becomes Reality protect the otherwise exposed junctions from contamination Only nine days after Hoerni’s and possible electrical leakage formal patent disclosure, Noyce, due to subsequent handling, stimulated in part by the urgings of cleaning, [and] canning of the the patent attorney, began writing in device.22 his lab notebook under the heading, This approach had the further “Method of isolating multiple 27 advantages that all electrical leads devices.” He thought it a terrible could be attached and all processing waste that all these transistors on a steps performed from the same single wafer had to be cut apart, have side of the silicon wafer—features leads attached to them individually, that would eventually prove to and then be soldered back together be of inestimable value when this with other components to assemble planar manufacturing process Fig. 6. Drawings from Robert Noyce’s patent on the complete circuits. What if all the was later applied to fabricating integrated circuit, showing how he proposed to use Hoerni’s interconnections could be instead planar processing technique to form the necessary p-n integrated circuits. With only placed directly on the wafer surface junctions in silicon beneath a protective oxide layer. Silicon during the manufacturing process? slight exaggeration, historian of is denoted by 11 here and silicon dioxide by 12. technology Christophe Lécuyer has Here again, the silicon-dioxide

The Electrochemical Society Interface • Fall 2007 39 Riordan then only to check up on how work was channels with an inert epoxy resin. But (continued from previous page) progressing.30 in the fall of 1960, p-n junction isolation Production of planar transistors was proved the superior alternative. The proceeding apace in 1959, especially group made successful prototype flip- layer played the key role as an enabling at the urging of Autonetics, a division flop circuits involving four transistors technology. of North American Aviation that was (Fig. 7) and followed them up with other “In many applications now it would building computer systems for the integrated logic circuits. In March 1961 be desirable to make multiple devices Minuteman missile and had extremely Fairchild announced the “Micrologic” on a single piece of silicon in order to be stringent demands for precision and family of integrated circuits, half a able to make interconnections between reliability. It helped Fairchild to learn year ahead of the Texas Instruments devices as part of the manufacturing that a Bell Labs group under M. M. competition. The use of Hoerni’s planar process, and thus reduce size, weight, Atalla had developed “thermal” methods processing technique had made all the etc., as well as cost per active element,” of growing the oxide, mitigating the difference.33 Noyce began.28 To Hoerni’s planar problems of dangling bonds and process, he added the provision that “surface states” at the interface between aluminum interconnections between Summary the oxide layer and the silicon.31 Using the individual devices be placed on top this thermally grown oxide layer, of the oxide layer, which would insulate Throughout this technological evo- Atalla and Dawon Khang subsequently these leads from the silicon beneath lution, from diffused-base transistors made the first truly successful field- it. And these circuit components to planar integrated circuits, the effect transistors in 1960—what soon could be electrically isolated from one silicon-dioxide layer discovered in became known as the metal-oxide- another by interposing back-to-back p- 1955 by Frosch and Derick remained semiconductor, or MOS, transistor (see n junctions between them. These were at the center of the action. Without article by Ross Bassett on p. 46) .32 the principal new ideas at the heart this supple, flexible interface between It took Last’s development team nearly of Noyce’s famous integrated-circuit silicon and its environment, the two years to produce commercially patent, titled “Semiconductor Device- microchip as we know it today would available integrated circuits using and-Lead Structure,” which he applied be unthinkable. It is the sine qua non of planar processing. Higher precision for later that year (Fig. 6).29 the semiconductor industry, and what was needed for oxide masking and The difficult task of actually most distinguishes silicon from all other photolithography—and more steps were fabricating microelectronic circuits material alternatives. involved. And a big problem was isolating according to these prescriptions fell to Although ultimately unsuccessful the circuit elements. Workers even Jay Last, who formed a development financially, the Shockley Semicon- attempted a physical-isolation approach group to realize this goal. In March 1959 ductor Laboratory played an important suggested by Last that involved etching Noyce took over as Fairchild’s General technology-transfer role in this saga. channels between the components from Manager and Moore replaced him as It acted as the crucial incubator where the back of the wafer all the way to the research director. Noyce rarely showed men came together with ideas on the fragile oxide layer, then filling these up in the laboratory after that—and West Coast, and began working together on the revolutionary implications of the new silicon technologies pioneered in the mid-1950s by Bell Labs. They were so revolutionary, in fact, that it took a small rebellion, much celebrated in Silicon Valley lore, to realize them. The development and implementation of planar processing at Fairchild Semiconductor Corporation was what really threw the floodgates open to extremely reliable silicon transistors and microchips of endlessly growing complexity. The junction transistor’s inventor, William Shockley, dimly perceived this bright future, but he lacked the management skills to bring it off under his direction. In the early 1960s, he began teaching at Stanford University, first as a lecturer and then as a professor of engineering and applied science, while his company slowly failed and was eventually dissolved. Yet without Shockley’s contributions in bringing together this stellar group of researchers and introducing them to silicon technology, there would be no Silicon Valley—at least not in Northern California. About the Author Fig. 7. One of the earliest prototype integrated circuits fabricated by Jay Last’s development group at Fairchild using the planar processing technique. Michael Riordan earned his PhD in This “flip-flop” logic circuit employed four transistors. (Courtesy of Fairchild physics from MIT. He is an adjunct Semiconductor Corp.) professor of physics at the University of California, Santa Cruz, and a Lecturer

40 The Electrochemical Society Interface • Fall 2007 at Stanford University. He is author Laboratories Record (June 1958), pp. Exposed p-n Junctions at the Surface of The Hunting of the Quark (Simon & 202-206. of Silicon Transistors by Oxide Schuster, 1987) and coauthor of Crystal 12. Shockley quoted by Moore, interview Masking Techniques,” 14 January Fire: The Birth of the Information Age with Hoddeson and Riordan. 1959, copy provided courtesy of Jay (W. W. Norton, 1997), which won the 13. William Shockley, “Golden West Last. 1999 Sally Hacker Prize of the Society Theme Book” (personal diary, 1956- 26. C. Lécuyer, Making Silicon Valley: for the History of Technology. A Fellow 57), Stanford University Archives, Innovation and the Growth of High of the American Physical Society and a Shockley papers, accession listing 95- Tech, 1930-1970, .p. 152, The MIT Guggenheim Fellow, he received the 153, box 2B, p. 58. Press, Cambridge, MA (2006). prestigious Andrew W. Gemant Award 14. The most compete reference on the 27. Robert N. Noyce, Fairchild Semi- of the American Institute of Physics. formation and early years of the conductor Corp. lab notebook, He may be reached at mriordan@ucsc. Fairchild Semiconductor Corporation pp. 70–74 (23 January 1959), copy edu. is Chapter 4 of Christophe Lécuyer’s provided courtesy of Jay Last. Making Silicon Valley: Innovation and 28. Robert N. Noyce, Fairchild Semi- the Growth of High Tech, 1930-1970, pp. conductor Corp. lab notebook, p. References 129–167, The MIT Press, Cambridge, 70 (23 January 1959), copy provided MA (2006). See also Riordan and courtesy of Jay Last. 1. M. Riordan and L. Hoddeson, Hoddeson, Crystal Fire, pp. 262-269, 29. Robert N. Noyce, U.S. Patent No. Crystal Fire, pp. 225-230, W. W. W. W. Norton & Co., New York 2,981,877, “Semiconductor Device- Norton & Co., New York (1997). (1997); Leslie Berlin, The Man Behind and-Lead Structure,” filed 30 July 2. Riordan and Hoddeson, Crystal the Microchip: Robert Noyce and the 1959, awarded 25 April 1961. Here Fire, pp. 230, W. W. Norton & Invention of Silicon Valley, pp. 82-157, it is crucial to note that Jack Kilby Co., New York (1997); Riordan Oxford University Press, New York had conceived similar ideas several and Hoddeson, Physics Today, p. 43 (2005); and Ross Knox Bassett, To months earlier at Texas Instruments, (December 1997). See also William the Digital Age: Research Labs, Start- and that the two men are generally Shockley, “Memorandums,” Up Companies, and the Rise of MOS perceived as the co-inventors (personal diary 1955–56), Stanford Technology, pp. 45-53, The Johns of the integrated circuit. Kilby, University Archives, Shockley Hopkins University Press, Baltimore, however, did not have any idea of papers, accession listing 95-153, MD (2002). the planar technology used in the box 2B. 15. C. Lécuyer, Making Silicon Valley: Noyce patent, and proposed that 3. Riordan and Hoddeson, Crystal Innovation and the Growth of High individual components on a chip be Fire, pp. 231-234, W. W. Norton Tech, 1930-1970, p. 150, The MIT connected by what became known & Co., New York (1997); Riordan Press, Cambridge, MA (2006). as “flying wires.” See Jack Kilby, and Hoddeson, Physics Today, p. 44 16. C. Lécuyer, Making Silicon Valley: IEEE Transactions on Electron Devices, (December 1997). Innovation and the Growth of High 23, 648 (July 1976); and Michael S. 4. Riordan and Hoddeson, Crystal Fire, Tech, 1930-1970, pp. 140-148, The Wolff, “The Genesis of the Integrated pp. 236-240, W. W. Norton & Co., MIT Press, Cambridge, MA (2006). Circuit,” IEEE Spectrum (August New York (1997). 17. M. Tanenbaum and D. Thomas, 1976), pp. 38–45. 5. F. J. Biondi, et al., Editors, Transistor “Diffused Emitter and Base Silicon 30. Jay Last, private communications. Technology, 3 Vols., D. Van Nostrand, Transistors,” Bell System Technical Lécuyer observes, “Interestingly, New York (1958); Vol. 3 is devoted Journal, Vol. 35 (January 1956), pp. Noyce played no role in this effort.” to diffusion technologies, including 1–22. See C. Lécuyer, Making Silicon Valley: contributions by Frosch, Fuller, 18. C. Lécuyer, Making Silicon Valley: Innovation and the Growth of High and Tanenbaum. Noyce attended Innovation and the Growth of High Tech, 1930-1970, p. 157, The MIT the third symposium as a Philco Tech, 1930-1970, p. 149, The MIT Press, Cambridge, MA (2006). employee. Press, Cambridge, MA (2006). 31. M. M. Atalla, et al., “Stabilization of 6. Riordan and Hoddeson, Crystal Fire, 19. C. Lécuyer, Making Silicon Valley: Silicon Surfaces by Thermally Grown pp. 241-243, W. W. Norton & Co., Innovation and the Growth of High Oxides,” Bell System Technical Journal, New York (1997). Tech, 1930-1970, pp. 149-150, The Vol. 38 (1959), pp. 749–783. 7. Riordan and Hoddeson, Physics MIT Press, Cambridge, MA (2006). 32. On the origins of the MOS transistor, Today, p. 45 (December 1997). 20. C. Lécuyer, Making Silicon Valley: see Ross Knox Bassett, To the Digital 8. C. J. Frosch and L. Derick, Journal of Innovation and the Growth of High Tech, Age: Research Labs, Start-Up Companies, The Electrochemical Society, 104, 547 1930-1970, pp. 150-152, The MIT and the Rise of MOS Technology, pp. (1957). Press, Cambridge, MA (2006); also 22–33, The Johns Hopkins University 9. Gordon Moore, interview with Jay Last, private communication. Press, Baltimore, MD (2002); and L. Hoddeson and M. Riordan, 11 21. Jean A. Hoerni, Fairchild Semi- Dawon Kahng, IEEE Transactions on January 1996. conductor Corp. lab notebook, pp. 3- Electron Devices, 23, 655 (July 1976). 10. Soon after Bell Labs research 4 (1 December 1957), copy provided 33. C. Lécuyer, Making Silicon Valley: director Mervin Kelly hired courtesy of Jay Last. Innovation and the Growth of High Shockley in 1936, he impressed on 22. Jean A. Hoerni, Fairchild Semi- Tech, 1930-1970, pp. 155-59, The MIT his new employee the needs of the conductor Corp. lab notebook, p. 3 Press, Cambridge, MA (2006); and Bell System to replace its unreliable (1 December 1957), copy provided Jay Last, private communication. electromechanical switches with courtesy of Jay Last. a better, faster solid-state version. 23. C. Lécuyer, Making Silicon Valley: Kelly’s urgings helped stimulate Innovation and the Growth of High Shockley to invent the junction Tech, 1930-1970, p. 150, The MIT transistor and probably promoted Press, Cambridge, MA (2006). his interest in the four-layer diode. 24. Jean A. Hoerni, “Planar Silicon See Riordan and Hoddeson, Crystal Transistors and Diode,” Fairchild Fire, pp. 81-82, W. W. Norton & Co., Semiconductor Report No. TP-14, New York (1997). p. 9, Fairchild Collection, Stanford 11. On the difficulties of fabricating University Archives. uniform, reliable four-layer diodes, 25. Jean A. Hoerni, Fairchild patent see W. J. Pietenpol, “Transistor disclosure, “Method of Protecting Designs: The First Decade,” Bell The Electrochemical Society Interface • Fall 2007 41