to focus the company’s talents and From Bell Labs to Silicon Valley: energies on devices that were then at the frontiers of semiconductor technology, A Saga of Semiconductor Technology Transfer, 1955-61* such as field-effect transistors and the four-layer p-n-p-n diode, often called the Shockley diode because he held by Michael Riordan a patent on it. At a given potential called the breakdown voltage, current would suddenly begin to flow through espite the fact that the Bell the two-terminal device, switching Telephone Laboratories had it from “off” to “on.” A remarkably Doriginated almost all the silicon simple, compact semiconductor switch, technology eventually used to invent it was the ultimate realization of a the integrated circuit, or microchip, this goal that had been subtly implanted revolutionary breakthrough occurred in Shockley’s mind at Bell Labs two elsewhere—at Texas Instruments, Inc., decades earlier.10 in Dallas, and Fairchild Semiconductor Although a brilliant conception, Corporation in Mountain View, however, the four-layer diode was California. In the latter case, the extremely difficult to fabricate with transfer of this technology occurred uniformity and reliability. Workers largely through the offices of a pivotal had to polish a silicon wafer to have but ultimately unsuccessful company, exactingly parallel planes on its Shockley Semiconductor Laboratory, FIG. 2. Senior staff of Shockley Semiconductor Laboratory toast their illustrious leader two sides and then carefully diffuse which had been formed by transistor William Shockley (seated at head of table) at a celebratory luncheon on 2 November impurities into the wafer from pioneer William Shockley. After 1956, the day after the announcement of his Nobel Prize. Seated at left is Gordon Moore both sides simultaneously. Lack of leaving Bell Labs in 1955, he brought and right of him is Sheldon Roberts. Robert Noyce stands in the middle and Jay Last is enough precision meant the diffused together a stellar team of scientists at far right, both lifting glasses. (Courtesy of Intel Corporation) impurities would penetrate to irregular, and engineers who later departed (in unpredictable depths, leading to FIG. 1. Shockley Semiconductor Laboratory at 391 San Antonio Road in Mountain View, September 1957) to found Fairchild, would be published in 1958 as the final on this important method. The preprint variations in the breakdown voltage California, as it appeared in 1960 after Clevite Corporation had purchased it and and other electrical characteristics.11 bringing a deep understanding of the volume in the classic series, Transistor also contained crucial new information renamed it Shockley Transistor Company. (Courtesy of Kurt Hübner) Noyce, Moore, and others thought diffused-silicon technologies they had Technology, which was becoming known about how to etch tiny openings in learned while employed by Shockley. throughout the semiconductor industry that layer and to use the remaining that this diode was much too difficult One pivotal contribution to silicon a project for the young company to proved satisfying. So by early 1955 of automatic means for production of as “Ma Bell’s cookbook.”5 Shockley oxide as a mask against the diffusion technology, however, originated entirely attempt at such an early stage in its Shockley was seeking to get back into diffused-base transistors.”3 could also call upon his old colleagues of trace impurities into the silicon. at Fairchild—the planar manufacturing evolution. We should concentrate industrial research—this time as the His original plan was to lure away Sparks, Tanenbaum, and Jack Morton, That technique would allow workers to process invented and developed by head of his own company.1 some of his most accomplished Bell head of device development, to visit the establish intricate patterns of n-type the physicist Jean Hoerni. This crucial In March 1955 his sense of urgency Labs colleagues, such as Tanenbaum new California company and consult and p-type material in the silicon. technique, in which an oxide layer on in these efforts was stimulated by news and Morgan Sparks, who had fabricated with his charges in their converted Shockley circulated this document the silicon surface is used to protect from Bell Labs. Not only had chemist the first junction transistors. But one Quonset hut at 391 San Antonio among his technical staff (Fig. the sensitive p-n junctions beneath it, Henry Theurer finally produced by one they turned him down that fall, Road (Fig. 1). They spent most of that 3), giving them all a crucial early has served ever since 1961 as the basis silicon with impurity levels of less claiming their families were too deeply first year purchasing or building the glimpse of what would become one of microchip fabrication. And Hoerni’s than a part per billion using float-zone rooted in New Jersey and they could necessary equipment, such as silicon of the core enabling technologies conception of this method occurred refining. But Morris Tanenbaum and not bear to leave Bell Labs. Thus he crystal growers and diffusion furnaces, for silicon integrated circuits and substantially earlier than most historical D. E. Thomas had also succeeded in subsequently criss-crossed the United and learning how to use it in making ultimately lead to the emergence of accounts have thus far reported. forming the first diffused-base (and States, trying to recruit the best possible semiconductor devices. Silicon Valley.7 By the time Frosch In this article, I try to set the record emitter) silicon transistor using samples scientists and engineers for Shockley On 1 November 1956, marvelous and Derick’s paper was published straight by recounting the important provided by Calvin Fuller (see article Semiconductor Laboratory. And he hired news reached the Mountain View firm in the Journal of The Electrochemical steps and major influences that brought by Nick Holonyak on p. 30). “Morrie some top-notch ones, too: physicists that Shockley had won the 1956 Nobel Society the following September, silicon technology to California—in Tann has AlSb plus Al bonded,” reads Hoerni from Caltech, Jay Last from Prize in physics for the invention of the Shockley and his staff were already the process laying the technological a cryptic note in Shockley’s pocket MIT, and Robert Noyce from Philco—as transistor, shared with John Bardeen developing ways to implement this foundations of Silicon Valley. notebook dated 23 March 1955, while well as physical chemist Gordon Moore and Walter Brattain. The next day they disruptive new technology.8 he was still at the Pentagon, referring from the Johns Hopkins Applied Physics stopped working before noon for a Silicon Technology Heads West to micrometers-thin aluminum and Laboratory. Among the eldest of this celebratory luncheon at nearby Rickey’s A Rebellion Erupts antimony impurity layers diffused into group at age 28, Noyce was about the Studio Inn in Palo Alto. A photograph 2 By 1954 William Shockley was the silicon. only one with extensive semiconductor of that gathering (Fig. 2), with Shockley But all was not well at the becoming increasingly frustrated by Over the next few months, Shockley experience, having developed high- at the head of the table being toasted by Mountain View laboratory. By his lack of professional advancement at began talking with executives at RCA, frequency germanium transistors at Noyce, Moore, Last, and others around 1957, members of the technical Bell Labs. Although head of transistor Raytheon, Texas Instruments and Philco.4 him, has achieved iconic status in the 6 staff had begun to resent Shockley’s research, he had been passed over for elsewhere about the possibility of Only Noyce among them had lore of Silicon Valley. often heavy-handed management higher positions and seemed mired starting a firm expressly devoted to attended the third Bell Labs symposium Upon returning from Stockholm style and his quirky selection of at this middle-management level producing diffused-silicon devices. For on transistor technology in January in mid-December, Shockley found a R&D projects. After a couple of despite his many publications and most of that summer, he met with 1956, devoted to the advanced package in his mail from the patent worrisome incidents, he started patents, including the all-important only passing interest until he spoke silicon technologies just then being licensing engineer at Western Electric investigating the backgrounds ones on the junction transistor. Thus with his friend and fellow Caltech developed—especially diffusion. But Company, AT&T’s manufacturing arm. of a few of his employees. And he began casting around for other alumnus Arnold Beckman, founder and because Beckman had licensed the rights It contained a preprint of an article by he gave one of them a vicious, possible positions, taking a leave of president of Beckman Industries, Inc. In to the transistor patents from Bell’s Carl Frosch and Lincoln Derick titled embarrassing tongue-lashing that absence to serve as a visiting professor early September they met in Newport parent company, AT&T, Shockley and his “Surface Protection and Surface Masking many others overheard. Several of at Caltech and as a military advisor Beach, California, and agreed to found new employees had ready access to the during Diffusion in Silicon.” Frosch the early employees were extremely FIG. 3. Copy of the 14 December 1956 letter to Shockley in the Pentagon’s Weapons Systems had delivered a paper on diffusion in 9 a new division led by Shockley