History Of Transistors

The other transistor: early history of the metal-oxide- sem-iconduaor f ielld-eff ect transistor by Robert G. Arns

The silicon metal-oxide-semiconductorjeld-e$ect transistor (MOSFET or MOS transistor) did not become signijkant commercially until two decades dJter the 1948 announcement ofthe invention ofthe transistor by Bell Laboratories. The underlying concept ofthe MOSFET--modulation o f conductivity in a semiconductor triode structure by a transverse electricjeld--rst appeared in a 1928 patent application. It was conlfirmed experimentally in 1948. However, early devices were not practical due to su@ce problems. Although these were solved at Bell Laboratories in 1958, Bell remained committed to earlier transistor technology. Development ofthe ‘other transistor’ wasjrst pursued elsewhere. It wasjnall‘y the needs o f computers and the opportunities created by integrated circuits that made the silicon MOSFET the basic element o f late 20th-century digital electronics.

device called a transistor, which has several applications in radio where a vacuum tube ordinarily is employed, was demonstrated for the first time yesterday at Bell Telephone

Laboratories.. .The device was demonstrated in a radio receiver, which contained none of the conventional tubes.. .’I

It is not surprising that the vacuum tube and radio shared the stage for the announcement of a new device that became known as the point-contact transistor. They were, after all, leading electronic technologies when Walter Brattain and John Bardeen made their discovery on 23rd December 1947. Brattain and Bardeen were members of a group headed by William Shockley and engaged in research on the electrical properties of solids at Bell Telephone Laboratories in Murray Hill, New Jersey. Their work was part of an effort aimed at the replacement of mechanical relays in telephone switching systems, an application for which the vacuum tube was deemed d-suited.

Although the point-contact transistor was never quite practical, the news ofits discovery inspired a flood of activity aimed at creating devices that would control the flow of electrical charges in solids. In early 1948 Shockley himself proposed a second three-element device, the bipolar junction transistor (BJT), essentially two diode junctions back-to-back in a block of semiconductor. The first BJT was made in 1950 and this device rapidly displaced the point-contact transistor and launched the transistor era2. It was the dominant transistor technology for another twenty years. In 1956 Bardeen, Brattain, and Schockley shared

the Nobel Prize in physics ‘for their researches on semiconductors and their discovery of the transistor effecf3.

Although work on early transistors was inspired by vacuum tubes, these devices were quite different in terms of the ways in which they worked. As one early text put it, ‘The transistor is basically a cuvvent operated device. Thus, the transistor operates as a current amplijier.. . The vacuum tube, on the other hand, operates as a voltage amplijier.. .’4. In the early years of the semiconductor industry there were many unsuccessful attempts to develop field-effect transistors (FETs), devices which would have been more closely analogous to the vacuum tube. It is almost obvious that it should have been so since the vacuum tube was such an important part of the education and thinking of an entire generation of electrical engineers and physicists. In many of these cases, problems of semiconductor surfaces took the blame when these FETs did not work-as they often also did when BJTs faded. Although a Bell Laboratories researcher learned how to tame these problems in 1958, Bell was by then committed to BJTs.

Over the next five years many other firms-RCA, Fairchild Semiconductor, and Texas Instruments, for example--were working on FETs and developing devices for special applications. As long as electronic circuits were expressed in terms of individual, discrete transistors, however, FETs remained a tiny part of the semiconductor device market. The first integrated circuits had been demonstrated in 1958; they contained two bipolar transistors connected on a single chip. Digital computers were also becoming increasingly

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important during this period as the lugher reliability of BJTs made more complex circuitry practical. The idea of putting multiple transistors on a single chip was attractive in computing applications whch used many replicas of a few basic circuits. The first microprocessor was announced by Intel in 1971. Computer memories were also being produced in integrated-circuit form. The recognition that MOSFET (metal-oxide-sern- conductor FET) technology would make integrated- circuit processing simpler and that more devices could be packed on a single chip finally led to its use for integrated circuits, be- ginning in about 1970. Within a decade silicon MOSFETs had taken over.

The field effect

The basic concept of an insulated-gate field-effect transistor (IGFET) is shown in Fig. 1. The IGFET has been the most common type of field- effect transistor fiom the first commercial shcon MOSFETs to the MOS technology later used in integrated circuits. It depends upon the modulation of the current in a conducting seiniconductor channel by a transverse electric field due to a gate electrode that is insulated &om the channel.

The insulating layer in an IGFET is analogous to the vacuum in a vacuum

stantidy alter the number offiee charge carriers withn the bulk of the semiconductor7. It is rather like having a layer of higher conductivity material on the surface of the semiconductor which shelds the bulk of the semiconductor.

Bardeen and Brattain set out to investigate these surface phenomena in the laboratory. In one such trial (on 21st November 1947) they were attempting to modulate the current in a block of shcon by applymg a voltage between the shcon and a drop of water

I thermally-grown silicon

Fig. 1 Schematic cross-section of an

leave through the drain, and are subject t controlling action of the gate in the region betwe heavily-doped n-type jun gate voltage, the large at the silicon surface a the inversion layer. Th type, leading to the device shown, or n-ty in which holes are cam course, required in n-b voltages are negative, rather than positiv source and substrate grounded. Note that applied to the drain in these MOSFETs is of reverse bias the diffused p-n junction at contact.

tube. In a properly biased vacuum tube there is no current in the circuit of the grid, which is thus akin to the IGFET’s gate. Several of the early attempts at producing an amplifier in a semiconductor were even more obvious attempts to mimic a vacuum tube. Early on Brattain and J. A. Becker had tried to make a triode fiom a copper-oxide rectifier by embedding a metal grid in the semiconductor material5. Shockley and Brattain tried again to imitate a vacuum-tube triode in 19396. Next they tried copper plates at the surface of copper oxide. Field-effect experiments resumed after the War. None of these attempts worked.

John Bardeen, who had joined Bell Laboratories in 1945, postulated that the charge carriers were being trapped by danghng bonds at the interface between the semiconductor and the insulator and that, as a result, the application of an electric field would not sub-

containing an electrolyte on the surface of the sihcon. The output was observed between the block and a metal point contact on the surface of the shcon block; the point contact was in the electrolyte, but insulated fiom it. They found amplification of power and current, but no voltage amplification. They switched to germmum. On 8th December 1947, they obtained a voltage amplification of 2 and a power amplification of 330. They also tried &fferent electrolytes. One of them caused the germanium surface to oxidise. They speculated that this accidental oxide &n might enable them to obtain a larger field. They changed the geometry to one which used a metal point contact as a charge- collecting electrode and an evaporated gold

contact over the thm oxide as a control electrode on the germanium. On 1 1th December 1947, they found that their oxide layer had a hole in it and did not insulate. While playing with this defective device, they noticed that if the control electrode was biased with polarity opposite to that usually employed (ix. if the control electrode was fowud biased relative to the semiconductor), modulation of the current in the circuit containing the point contact occurred in response to a change in the voltage applied to the control electrode. T l s led to the idea of ‘injection’ of charge carriers’. All work prior to this date had been aimed at investigating field-effect devices. As noted earlier, on 23rd December 1947, less than two weeks later, a device using two closely-spaced point contacts was operated as an amplifier. They were off in a new drection.

Although the new point-contact device was the centre of much attention in the months that followed,


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Fig. 2 Although William Shockley’s US Patent No. 2,569,347 is renowned as the origin of the bipolar junction transistor (BJT), that device appeared as the third figure of the patent. The first figure is a gated p-n junction, Le. a type of insulated-gate field-effect transistor. Both devices are shown here. The material indicated as ’15’ is a drop of electrolyte in which the gate electrode (f6) is immersed. According to the patent, this is ‘in the nature of a capacitive connection since there is substantial isolation between the electrolyte and the surface of the body’.

field-effect ideas were not totally set aside. The point- contact transistor patent application was accompanied by two other applications embodying field-effect concepts; and Shockley’s junction transistor patent contained a field-effect device that is shown in Fig. 2’.

In 1952 Shockley and his co-workers also proposed and experimented with another way of producing a field effect which cbd not involve an insulated gate. This junction field-effect transistor (JFET) did not lead very far-at least at Bell Laboratories”’. In 1955 Bell Laboratories made a commitment to concentrate on silicon bipolar junction transistors.

Precursors

In 1964 the name ofJulius Edgar Lhenfeld surfaced in a Physics Today article by a physicist named Virgil Bottom. He had seen Lilienfeld’s obituary and recalled having found three patents on solid-state devices bearing Lilienfeld‘s name. In his brief paper Bottom drew attention to these patents and asked whether Lilienfeld was the actual discoverer of the transistor effect”.

A quick response by J. B. Johnson-a well-known physicist after whom ‘Johnson noise’ is named-then recently retired &om Bell Labs, seemed to put the matter to rest. In his response he expressed scepticism about Lilienfeld’s solid-state devices and stated that ‘ . . .at one time I tried conscientiously to reproduce Lilienfeld’s structure accordmg to his specification and could observe no amplification or even modulation’. Johnson’s response also mentioned Shockley’s JFET”.

In 1991 Bret Crawford, in his physics MS thesis, reported an experimental reconstruction of Lilienfeld’s US Patent No. 1,900,018 using technology that was available in 1928, when the patent application was filed, and known to Lilienfeld13. The basic idea of the device

is shown in Fig. 3. Following the prescriptions in the patent, he produced workmg devices, but they were unstable and the results were difficult to reproduce. That was not surprising since the semiconductor, cuprous sulphide, is no match for modern single-crystal silicon. Cradord also found signs that Lilienfeld had actually built the devices he patented-and not merely thought about them-in the form of close agreement between phenomena described in the patent and his own observations.

In 1995 Joel Ross replicated the prescriptions of the same Lilienfeld patent. He was able to produce devices that remained stable for months. Although these devices showed the field effect, the transconductance was poor, apparently due to surface states. The power gains, however, were ~ignificant’~.

At about this time, I was examining the legal files of the application proceedings which led to the two Bell ‘Nobel Prize’ patents for evidence of the part that earlier publications and patents might have played in the Bell patents. I found that Lihenfeld’s patents were very much present in these files. Bardeen and Brattain’s point-contact transistor patent application was submitted with 69 claims; only 19 were allowed. Thirty- six claims involving the basic ideas of transistor action were disallowed outright on the basis of prior claims in earlier patents, especially those of Lhenfeld. Shockley’s BJT patent was submitted with 62 claims; only 34 were granted. A total of 65 claims were abandoned or dmllowed in these two patents; the reason most frequently cited for disallowing a claim was Lilienfeld’s prior art.

In the file which led to Bardeen and Brattain’s point- contact transistor patent there was also an affiidavit submitted by Well Laboratories in an attempt to weaken Lhenfeld’s claims. In t h s sworn 24-page legal document, the author, J. B. Johnson-the same/. B.


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Fig. 3 This figure, from Lilienfeld’s US Patent No. 1,900,018, has been embellished by the additions of the letters 5, G, and D corresponding to the modern field-effect transistor designations, source, gate, and drain. The gate material ( IO) is aluminium. It is insulated by a thin layer of aluminium oxide (11) from the p-type semiconductor, CuzS (12), which is ‘depressed’ and of ‘molecular thickness’ at 13, where the modulation of conductivity occurs. The source and drain contacts (14 and 15) are conductors. The semiconductor and the source and drain contacts are vacuum evaporated. Unlike the silicon MOSFET shown in Fig. 1, this depletion-mode MOSFET does not have diode junctions at both the drain and source.

Johnson-reported that he had headed a group assigned to try the devices described in the three Lhenfeld patents. His testimony, dated 21st September 1949, begins with a description of the work on US Patent No. 1,900,018, the one replicated by Bret Crawford and independently by Joel Ross. It reads as follows:

‘...The first [Lilienfeld] patent I undertook to investigate was.. .1,900,018.. . Prior to my assign- ment.. .two other members of the Laboratories’ staff, namely, Wham Shockley and Gerald L. Pearson, had investigated the performance of a structure whch is the same in all particulars except one, namely, that the insulating h, instead of being aluminum oxide, was quartz.. .Shockley and Pearson reported the results in.. .the Physical Review for July 15, 1948.. . . . .although the modulation index of 11 per cent is not great,. . .the useful output power is substantial.. . it is in principle operative as an amplifier.’

The remainder of the affidavit is devoted to Johnson’s report on h s unsuccessful attempts to replicate the other two patents. The report of the Shockley and Pearson field-effect experiment appeared in the Physical Review adjacent to the Bardeen and Brattain paper announcing the point-contact tran~istor’~.

Lhenfeld published many articles in scientific journals on topics such as thermionic emission, X-rays, field emission, transition radiation, and the electro- chemistry of electrolytic capacitors. He never wrote an article on his transistors. His only reference to the scientific basis for his transistors was found in the Nes leading to one of the patents. He cited a 1915 theory by J. J. Thomson in which a semiconductor is characterised as a lattice of quasi-molecular units in which the centre ofpositive charge in each is separated from the centre of negative charge’6. Thomson

postulated that the application of an electric field tends to ahgn the molecules and change the conductivity. The first quantum-mechanical treatment of conduction in metals and semiconductors &d not appear until 1931, after Lihenfeld had submitted hs patent applications’’. Lilienfeld, working in 1925-1928, could not have used terminology like +type’, ‘holes’, ‘Fermi level’, or ‘energy bands’.

Oskar Heil of the University ofBerlin filed a British patent application in 1935 which contains the first description of an insulated-gate FET that hinted at the new semiconductor concepts18. The basic scheme is shown in Fig. 4. Both p-type and n-type semiconducting thin films are described in the patent. Heil’s prior art also figured in the rejection of claims in the patent applications of Bardeen, Brattain, and Shockley. Published scientific, technical, and hstorical papers by these Bell scientists never mention either Lilienfeld’s or Heil’s prior work.

The return of the field effect

As noted above, by 1955 the emphasis at Bell Laboratories had become shcon BJTs, and although these bypassed the worst problems of the semiconductor surface, since interfaces were within the bulk semiconductor, junction transistors had other surface problems. The surface affected properties such as leakage currents and device stabhty; surface problems were a frequent cause of device fdures. In 1956 M. M. Atalla was made head of a group to work on surface problems. Eventually hs work focused on the oxidation of the &con surface as a means of solving one type of surface problem. He presented I s work on thermally-grown silicon &oxide at a 1958 conference’’. It was warmly received.

In the course of t h s work, Atalla proposed a new semiconductor device, which is now known as the


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silicon MOSFET. It was ap-channel device very much like that described in Fig. 1. Dawon Kahng, a member of Atallai group, built such a device and he and Atalla reported on it at the 1960 Solid State Device Research Conference. They were not encouraged to publish the work, however, and the only written record is an internal Bell Memorandum tojle2”. Kahng and Atalla had both been assigned to other work by the time the Memorandum was written.

The first use of the (Atalla et al.) &con surface passivation technique in a commercial product was reported in 1960 by Jean Hoerni at Fairchild Semiconductor Corp.” It was an improvement in the fabrication process for bipolar transistors (as dstinct from FETs) called the planar process. Bell did not start a development project using MOS technology until 1966.

Meanwhile many other firms continued to experiment with field-effect devices. For example, in 1961 Paul Weimer and his co-workers at RCA developed an IGFET using thin-film technology, polycrystalhne cadmium sulphde (CdS) as the semiconductor, and an evaporated layer of silicon monoxide or calcium fluoride as the insulatoP. These devices were less sensitive to surface-state problems, but CdS is far &om an ideal semiconductor. They were not a commercial success. However, a year later, Hofstein and Heiman, also of RCA, published a study of the silicon MOSFET, which held more promisez3.

Work at Fairchild was particularly significant for the subsequent development of MOSFET technology. As noted above, the planar hffusion process, the standard method for fabricating semiconductors to the present, had its inception there in 1960. The CMOS (complementary MOS) concept, which proved to be extremely important in reducing power use by MOS transistors, was first reported by Wanlass and Sah of Fairchild in 196324. The first commercial discrete MOS transistors were announced by Fairchild and RCA in late 1964; both used slllconZ5. The market for discrete MOS transistors was relatively small, however, and confined to a limited class of applications. For most uses they did not perform as well as their well-established BJT competitors.

MOSFET technology would not have achieved its current importance ifit were not for the emergence of the computer industry. Moreover, its prominence there depends on the development of the integrated circuit. The concept of the integrated circuit had begun to emerge as soon as both the need and the potential for miniaturisation were recogmsed. For example, in 1952 G. W. A. Dummer of the Royal Radar Establishment (Malvern) described the natural successor to the indwidual transistor in terms of ‘electronic equipment in a solid block with no connecting wires. The block may consist of layers of insulating, conducting, recti- firing and amplifying materials, the electrical functions being connected &rectly by cutting out areas of the various layers.’26 The fdure of the British government to support his work, which involved The Plessey Co.

Fig. 4 Illustrations from Oskar Heil’s British Patent No. 439,457. The two ends of the thin film of semiconductor (3) are covered by conducting stripes (1 and 2), which serve as source and drain. The gate is a conducting film (6) overlapping the semiconducting film, but separated from it by insulating material (8).

Ltd., has been widely viewed as a missed opportunity. In September 1958 Jack Kilby at Texas Instruments put a simple (flip-flop) circuit involving two bipolar transistors on a single chip of germanium using gold wires for the connections between the transistors. Nor was that step the answer. What is known today as the integrated circuit awaited other developments, including shcon surface passivation and the planar process. Shortly after Kdby’s work, Robert Noyce demonstrated what became known as the ‘monolithic’ integrated-circuit technology (as distinct &om the ‘hybrid’ technology of Kdby) which placed &con diffused bipolar transistors and resistors on a single Si chip and interconnected them by aluminum lines produced using photolithography”.

These early integrated-circuit concepts were emerging at a time when hgital computers, made more reliable and affordable by solid-state components, were enjoying a period of vigorous growth. It was application to computer memories and micro- processors that finally assured the silicon MOSFET the place of importance it enjoys today. The ferrite-core dynamic memories of early computers were initially challenged by monolithic integrated circuits using bipolar transistors and storage cell architectures whch


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required multiple transistors for each bit stored. The IBM System 360, Model 91 computer, announced in Januar, 1966, featured chps having a 16-bit array of memory; each bit required five bipolar transistors. The total capacity of the semiconductor portion of the Model 91’s memory, used for storage protection, was 1024 9-bit words2’. In 1970 the IBM System 370, Model 145 computer contained 128-bit bipolar dynamic random-access memory (DRAM) chips. The first coinmercial MOS DRAM was also announced by Intel in 1970. It featured a three-transistor cell and packed 1024 bits on a single c h ~ p ~ ~ .

There were two advantages ofMOS technology that were recognised and that brought it to the fore at t h s time. First, MOS technology required fewer processing steps than bipolar technology; that translated into lower costs and larger fabrication yields. Second, although BJTs could not be scaled down in size without harming their operating characteristics, MOSFETs could be scaled without compromising performance. In fact, it was necessary to scale the dimensions down by large factors and to reduce voltages in order to make MOSFETs technologically competitive. It was also necessary to move to large-scale integration in order to reduce packaging capacitances and thereby reduce signal delays. ScAng down MOSFET dimensions improved speed and decreased the power dmipation of each transistor. At the same time, scahng provided what computer applications needed, the potential for more devices and operations per unit area at a smaller cost per device.

A critical step for computer technology was the development of the MOSFET single transistor- capacitor unit memory cell by R . H. Dennard at the IBM Yorktown Heights Research Laboratory in 196730. With this step, MOS technology provided not only lower power dissipation and fewer processing steps but also much greater density of bits per chp. As noted above, by 1970 Intel was producing single-chp 1024- bit MOS integrated-circuit memories based on a three transistor per bit archtecture. By early 1973 several manufacturers were reporting and/or selling 4096-bit MOS one-transistor-cell DRAMs3’. By 1985,1000 000 bits per chip had become the standard. The single-transistor DRAM cell is now the most abundant man-made object on earth.

In 1971 Intel announced the first microprocessor, the 4004, then called a ‘micro-programmable computer on a chp’. Ths MOSprocessor, whch used words of 4-bit length, contained about 2300 transistors. In 1990, the Intel 80486 microprocessor chip carried 1 000 000 devices. Here, too, MOS technology was the key to growth.

MOSFET’s long wait

This sketch of some of the highhghts in the more than 40 year history of the MOSFET from its earliest beginnings in Lihenfeld’s 1928 patent application raises a number of interesting questions about the develop-

ment of t h s technology. Why, for example, d d solid- state field-effect devices not receive more attention in the 1930s? Lhenfeld’s experience is instructive on ths matter. Lhenfeld’s first US transistor patent application was Wed in 1926, barely two weeks after he had resigned h s appointment at the University of Leipzig. The other two applications were Wed in 1928 at about the time he began working for h a d Corporation, a Massachusetts manufacturer of electronic components for radios. There he made important contributions to the development of electrolytic capacitors. In 1930 Magnavox bought b r a d and established an inde- pendent entity, called Ergon Research Laboratory, headed by Lilienfeld, where he continued to work on capacitor technology until Ergon was closed in 1935.

It is clear from the records that Lilienfeld owned the transistor patents. h a d and Magnavox would have been natural customers for these patents. Lilienfeld was apparently unsuccessful in interesting them or others in the devices32. There seem to be plausible reasons for the lack of interest. First, it was the period of the Great Depression; there was very little capital to invest in long-term research and development projects. Second, the dominant electronic technology of the time was radio; vacuum tubes were deemed very satisfactory for that application. Third, the radio and the automobile were two important symbols of social attainment, the rad0 in the living room and the automobile outside of the home. Rados of the period were featured as home furnishings, the ‘electronic hearth’ around which the ‘modern’ family gathered. These radios were installed. in large cabinets of fine furniture quahty. Advertising featured the number of vacuum tubes in the rado as an indicator of quahty-the more the better. Smaller components using less power would have suggested quite the opposite. These features of the culture of the 1930s contrast sharply with the condtions after World War 11, when wartime developments in radio, radar, and electronically-controlled weapons had shown the value of reliability, as electronics became more complex, size, especially as electronic systems were put into aircraft, and reduced power requirements.

Why, secondly, did Bell Laboratories personnel fail to acknowledge the earlier work of persons such as Lhenfeld and Heil? None of the Bell publications on transistors carries a reference to their work, not even the 1948 paper in whch Shockley and Pearson demonstrated the field-effect experimentally We also have J. B. Johnson’s 1964 public response to Virgil Bottom compared to the admission contained in his 1949 &davit filed in support of patent proceedings: the 1964 statement, by fading to mention Shockley and Pearson’s 1948 confirmation of Lhenfeld’s US Patent No. 1,900,018, appears to have been deliberately misleadmg. .The official history of the Bell System electronics work mentions Lhenfeld’s and Heil’s patents only in endnotes to a footnote. The footnote speaks of earlier patents whch ‘date back to the 1920s’ and states that ‘apparently all attempts to realise these concepts were fu t~ le’~~. In 1988, John Bardeen finally


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adrmtted that ‘He [Lilienfeld] had the basic concept of controlling the flow of current in a semiconductor to make an ampli6ing devi~e’’~. It seems possible that Shockley et al. had given up on the MOSFETidea due to surface problems; otherwise the admission, in Johnson’s affidavit, that the Shockley and Pearson experiment corresponded to Lihenfeld’s patent, would not have been so easy. It is also likely that they were silent and/or dismissive in their own publications and utterances in order to bolster their patent applications and to minimise challenges to their priority.

Bell faded to recognise the value of the silicon MOSFET a second time, i.e. in 1960, when it was developed in house by Atalla and Kahng. There were probably several reasons. First, by 1955 (five years earlier) Bell had made a strong commitment to Shockley’s bipolar junction-transistor technology. The 1960 MOS technology was inferior to the 1960 junction transistor technology-Kahng and Atalla’s first MOS device was 100 times slower than the best junction devices-and, whereas semiconductor surfaces represented a second-order effect for the junction transistor, they would s t d be a first-order effect for the FET. The MOSFET would have required a long period of development. Second, other Bell researchers had announced another important innovation at the same 1960 conference, the epitaxial transistor, which promised a significant improvement in junction-transistor technology. Third, Bell was not in the business ofmaking devices to sell. The upgradmg of Bell’s operating systems was seen in terms of long- term capital investment. This favoured stabilisation of the technology rather than a continuing stream of innovation^^^.

The point contact transistor, whose fiftieth anniversary was recently celebrated, was merely a detour. John Bardeen said as much in an interview: his ‘discovery with Brattain of the point contact transistor may have slowed the advancement ofthe transistor field because it diverted the semiconductor program &om junction and field-effect transistors which subsequently proved to be far more useful commercially.. . [Had] the oxide layer been insulating as expected [on that day in December 19471, the first successful transistor would have been a field-effect rather than a point-contact device.. .’36.

It wdl be much more difficult to mark the anniversary of the other transistor, the MOSFET. Its concept appeared prematurely, before it could be reahsed in commercial form using existing technical knowledge. There were hundreds of steps along the way and, in the end, the needs of the modern digital computer and the unique advantages that MOS technology brought to computing applications provided the persuasive motivation for the efforts that secured the MOSFET’s place in technological hstory.

Acknowledgments

I am grateful to Bret Crawford of Gettysburg College,

Joel Ross of St. Michael’s College, and Brian Melody of Kemet Electronics Corporation for their advice on this paper and for their contributions to this work; and to Professor Dale L. Critchlow, University ofVermont, for his advice on this work.

References

1 ‘News ofradio’ column, The New York Times, 1st July 1948, p.46

2 The early history of these devices is described by BRAUN, Ernest and MACDONALD, Stuart in ‘Revolution in miniature’ (Cambridge University Press, Cambridge and New York, 2nd edn. 1982)

3 The patents often associated with this recognition are: US Patent 2,524,035, ‘Three-electrode circuit element utilizing semiconductive materials’, the point-contact transistor patent issued to Bardeen and Brattain on 3rd October 1950; and US Patent 2,569,347, ‘Circuit element using semiconductive material’, the BJT patent issued to Wdham Shockley on 25th September 1951. Shockley’s notebook shows the date for the genesis of the idea as 23rd January 1948

4 GARNER, L. E., Jr.: ‘Transistors and their applications in television-radio electronics’ (Coyne Electrical School, Chcago, 1953), p.36

5 WEINER, C.: ‘How the transistor emerged’, IEEE Spectrum, 1973, 10, pp.24-33

6 SHOCKLEY, W.: ‘Creative-failure methodology’, Elec- tronics and Power, 22, February 1973, p.59

7 BARDEEN, J.: ‘Sudace states and rectification at a metd semiconductor contact’, Phys. Rev., 15th May 1947, 71, pp.717-727; the paper was submitted in March 1946

8 HODDESON, L.: ‘The discovery of the point-contact transistor’, Historical Studies in the Physicul Sciences, 1981, 12,

9 US Patent 2,524,033, issued to John Bardeen on 3rd October 1950, is a sourceless MOSFET; US Patent 2,524,034, issued to Brattain and Gibney on 3rd October 1950, is a field-effect device incorporating a drop of electrolyte. Figure 1 of Shockley’s US Patent 2,569,347 i s a gated p-n junction, i.e. an inversion-channel insulated-gate FET.

10 References to the JFET, which is not described in this article, include SHOCKLEY, W : ‘A unipolar “field-effect” transistor’, Roc. I R E , 1952,40, pp.1365-1376; DACEY, G. C., and ROSS, I. M.: ‘Unipolar “field-effect” transistor’, Proc. IRE, 1953, 41, pp.970-979, ‘The field-effect transistor’, Bell Syst. Tech.J, 1955, 34, pp.1149-1189, and ‘Semiconductor signal translating devices’, US Patent No. 2,778,956, granted on 22nd January 1957 (application date 31st October 1952). Stanislas Teszner used a germanium- alloy construction in a 1957 version of the JFET, see TESZNER, S.: ‘Le Tecnetron, nouveau dspositif se&- conducteur’, in DESIRANT, M., and MICHIELS, J. L. (Eds.): ‘Solid state physics in electronics and tele- communications’. Proc. Int. Conf., Brussels, 2nd-7th June 1958,2, Pt. 2, pp.1086-1099 (Adademic Press, London and New York., 1960); German Patent No. 1,013,796, issued 14th August 1957. MORRIS, E? R., describes later JFET developments at Crystalonics and Texas Instruments in ‘A history of the world semiconductor industry’ (Institution of Electrical Engineers, London, 1990), pp.43-44

11 BOTTOM, V. E.: ‘Invention of the solid-state amplifier’, Physics Today, February 1964, pp.24-26; Lilienfelds US

pp. 4 1-73

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Patents Nos. 1,745,175 (applied 8th October 1926, and IEEE 1963 Int. Solid-state Circuits Conf., 20th February granted 28th January 1930), 1,877,140 (applied 8th 1963, pp.32-33; and WANLASS, E M.: ‘Low stand-by December 1928, and granted 13th September 1932), and power complementary field effect circuitry’, US Patent 1,900,018 (applied 28th March 1928, and granted 7th No. 3,355,858 (applied 18th June 1963, and granted 5th March 1933) December 1967)

12 JOHNSON, J. B.: ‘More on the solid-state amplifier and 25 SAH, Chh-Tang: ‘Evolution ofthe MOS transistor-from Dr. Lilienfeld’, Physics Today, May 1964, pp.60-62; the conception to VLSI’, Proc. IEEE, 1988,76, pp.1280-1326,

13

14

15

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19

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quote is from p.61. The language used by Johnson suggests that he is describing an attempt to verify Lhenfeld’s US Patent No. 1,745,175. References to the JFET work of Shockley and of Dacey and Ross are given in Reference 10 above CRAWFORD, B. E.: ‘The invention ofthe transistor’. MS Thesis, The University ofVermont, October 1991 ROSS, J. P.: ‘Reconstruction of a Lilienfeld transistor’, paper presented to the‘ Spring 1995 Meeting of the New England Section ofthe American Physical Society, 8th April 1995; also reported in ‘J. E. Lilienfeld and the mscovery of the transistor effect’, Old Timer’s Bulletin, February 1998,39, pp.44-47 and May 1998,39, pp.50-52 SHOCKLEY, W., and PEARSON, G. L.: ‘Modulation of the conductance of thin films ofsemi-conductors by surface charges’, Phys. Rev., 15th July 1948, 74, pp.232-233; BARDEEN, J., and BRATTAIN, W H.: ‘The transistor, a semi-conductor triode’, Phys. Rev., 15th July 1948, 74,

THOMSON, J. J.: ‘Conduction of electricity through metals’, Philor. Mug., Series 6, 1915, 30, pp.192-202 WILSON, A. H.: ‘The theory of electronic semiconductors, 1’, Proc. R. Soc., 1931, A133, pp.458-468; and

HEIL. 0.: ‘Improvements in or relating to electrical amplifiers and other control arrangements and devices’, British Patent No. 439,457, granted 6th December 1935; British application dated 4th March 1935, based on German application dated 2nd March 1934. Other early field-effect devices whch formed part of the patent record are noted by GOSLING, W, TOWNSEND, W: G., and WATSON, J.: ‘Field-effect electronics’ Wiley Interscience, New York and Toronto, 1971), pp.6-9 ATALLA, M. M., TANNENBAUM, E., and SCHEIBNER, E. J.: ‘Stabilization of silicon surfaces by thermally grown oxides’, Bell Syst. Ech.J., 1959, 38, p.749-783 KAHNG, D., and ATALLA, M. M.: ‘Shcon-shcon dioxide field induced surface devices’, IRE-AIEE Solid- State Device Res. Conf., Carnegie Inst. of Technology, Pittsburgh, PA, 27th-29th October 1960; KAHNG, D.: ‘Sdicon-shcon dioxide suriace devicecase 38589-35’, Technical Memorandum to file 61-2821-1 (16th January 1961), Bell Laboratories Archives HOERNI, J. A,: ‘Planar shcon transistors and diodes’, IRE-AIEE Solid-state Device Res. Cod., 27th-29th October 1960, the same conference at which Atda and Kahng described their sficon MOSFET WEIMER, P K.: ‘An evaporated thin-film triode’, presented at the IRE-AIEE Solid-state Device Res. Conf., Stanford University, June 1961; ‘The TFT-A new thin- film transistor’, PVOC. IRE, 1962, 50, pp.1462-1469, and ‘An analysis of the characteristics of insulated-gate thn-film transistors’, RCA Rev., June 1963, pp.153-165 HOFSTEIN, R. , and HEIMAN, E F!: ‘The shcon insulated-gate field-effect transistor’, Electron Devices Conf., Washington, DC, 25th-27th October 1962 and Proc. IEEE, 1963, 51, pp.1190-1202 WANLASS, E M., and SAH, C. T.: ‘Nanowatt logic using field-effect metal-oxide semiconductor triodes’, Digest of

pp.230-232

‘ ..., 11’, PVOC. R. SOC., 1931, A134, pp.277-287

describes a few of the hundreck of steps in the evolution of MOSFET, includmg, pp. 1296-1297, the introduction of these MOS transistors in 1964

26 DUMMER, G. W. A,: ‘Electronic components in Great Britain’, in ‘Progress in quality electronic components’, Proc. Symp. of the IRE-AIEE-RTMA, Washington, DC, 5th-7th May 1952, p.19

27 NOYCE, R. N.: ‘Semiconductor device and lead structure’, US Patent 2,981,877, filed 30th July 1959, granted 25th April 1961; see also KILBY, J. S.: ‘Invention of the integrated circuit’, IEEE Puns. Electron Devices, 1976,

28 PUGH, E. W, CRITCHLOW, D. L., HENLE, R. A., and RUSSELL, L. A.: ‘Solid state memory development in IBM’, IBMJ Res. Dev., September 1981, 25, pp.585-602

29 REGITZ, W M., and U P , J. A,: ‘Three-transistor-cell 1024-bit 500-ns MOS RAM’, Digest Int. Solid-state Circuits Conf., February 1970, pp.42-43, and IEEE J. Solid-state Circuits, October 1970, SC-5, pp.181-186

30 DENNARD, R . H.: ‘Field-effect transistor memory’, US Patent 3,387,286, granted 4th June 1968, application dated 14th July 1967; see also DENNARD, R. H.: ‘Evolution of the MOSFET dynamic W - a personal view’, IEEE Xum. Electron Devices, 1984, ED-31, pp.1549-1555

31 These included Intel, Mostek, General Instrument, and Phllips; see, for example, PROEBSTING, R. , and GFLEEN, R.: ‘A TTL compatible 4096-bit n-channel RAM’, Digest IEEE Int. Solid-state Circuits Conf., 14th February 1973,

\XI, and BOONSTRA, L.: ‘A 4096-bit one-transistor-per- bit RAM with internal timing and low dmipation’, Digest IEEE Int. Solid-state Circuits Conf., 14th February 1973,

32 On 6th April 1949, Lhenfeld finally sold his transistor patents to Power Condenser and Electronics Corporation ‘for $5000 and other consideration’. The three patents had 5 months, 11 months, and 13 months of protection remaining

33 HORNBECK, A,: ‘The transistor’, Chap. 1 in SMITS, E M. (Ed.): ‘A hstory of engineering and science in the Bell System: electronics technology (1926-1975)’ (AT&T Bell Laboratories, 1985), pp.l-100; footnote is on p.3. Endnotes 4 and 5 (p.94) give names, numbers and dates ofthe patents of Heil and Lilienfeld

34 Letter to W&am Sweet, Associate Editor of Physics Today, dated 9th March 1988

35 This analysis of the reasons for Bell’s fdure to pursue the MOSFET is due to BASSETT, R. K.: ‘New technology, new people, new organizations: the rise of the MOS transistor, 1945-1975’, PhD Dissertation, Princeton Uni- versity, January 1998

36 HODDESON, L.: ‘The discovery of the point-contact transistor’, loc cit.; quote is from note 100

ED-23, pp.648-654

pp.28-29; LAMBRECHTSE, C. W, SALTERS, R. H.

pp.26-27, 194

0 IEE: 1998

Robert Arns is Professor and Dean ofthe College ofEngineer- ing and Mathematics, The University of Vermont, 109 Votey Building, Burlington, Vermont 05405-0156, USA


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