Alec Broers, Baron Broers

The Right Honourable
The Lord Broers

Sir Alec Broers, then President of the Royal Academy of Engineering (far left), and HRH The Duke of Edinburgh (centre) welcome Dr Hitoshi Narita as fellow of the Academy in 2002.
Vice-Chancellor of the
University of Cambridge
In office
1996-2003
Chancellor HRH The Duke of Edinburgh
Preceded by David Glyndwr Tudor Williams
Succeeded by Alison Richard
Personal details
Born (1938-09-17) 17 September 1938
Calcutta, India
Alma mater Geelong Grammar School
Melbourne University
University of Cambridge

Alec Nigel Broers, Baron Broers, FRS FMedSci FREng[1] (born 17 September 1938) is a British electrical engineer.[2][3]

Education and early life

Broers was born in Calcutta, India and educated at Geelong Grammar School and Melbourne University in Australia and at University of Cambridge (Gonville and Caius College) in England.

Career

Broers then worked in the research and development laboratories of IBM in the United States for 19 years before returning to Cambridge in 1984 to become Professor of Electrical Engineering (1984–96) and Fellow of Trinity College, Cambridge (1985–90). He is a pioneer of nanotechnology.

Broers subsequently became Master of Churchill College, Cambridge (1990–96) and Head of the Cambridge University Engineering Department (1993–96). He was Vice-Chancellor of Cambridge University, 1996–2003. In 1997 he was invited to deliver the MacMillan Memorial Lecture to the Institution of Engineers and Shipbuilders in Scotland. He chose the subject 'The Role and Education of the Creative Engineer'. He was knighted in 1998 and created a crossbench life peer in 2004, as Baron Broers, of Cambridge in the County of Cambridgeshire. Lord Broers was Chairman of the Science and Technology Committee of the House of Lords from 2004 to 2007 and was President of the Royal Academy of Engineering from 2001 to 2006.

In September 2008, Lord Broers took over from Sir David Cooksey as chairman of the board of directors at the Diamond Light Source, the United Kingdom's largest new scientific facility for 45 years.

Awards and honours

Lord Broers has received more than twenty honorary degrees and fellowships from universities, colleges, and academic and professional institutions. He is a Foreign Member of the US National Academy of Engineering, the Chinese Academy of Engineering, the Australian Academy of Technological Sciences and Engineering, and the American Philosophical Society. He was elected Fellow[4] of the Royal Academy of Engineering[5] in 1985.

Career summary


Research

Alec Broers began his research career in the Engineering Department of the University of Cambridge in 1961 working with Professor Oatley, and later with Dr William C Nixon, on the in situ study of surfaces undergoing ion etching in the scanning electron microscope (SEM). The microscope he used had originally been built by Oatley and had then been modified Garry Stewart who had also added an ion source that focussed ions onto the sample surface. Garry Stewart, who was another of Professor Oatley's students, then moved to the Cambridge Instrument Company where he oversaw the design and building of the world's first commercial SEM, the Stereoscan. During his PhD Alec rebuilt the SEM fitting a magnetic final lens in place of the original electrostatic lens thereby improving the microscope's resolution to about 10 nm, and after examining ion etched surfaces, used the microscope's electron beam for the first time to write patterns,[7] subsequently using ion etching to transfer these patterns into gold, tungsten and silicon structures as small as 40 nm. These were the first man-made nanostructures in materials suitable for microelectronic circuits opening up the possibility for the extreme miniaturization of electronic circuits that was to occur in the decades to come.

After graduating from Cambridge, Lord Broers spent nearly 20 years in research and development with IBM in the United States. He worked for sixteen years at the Thomas J Watson Research Centre in New York, then for 3 years at the East Fishkill Development Laboratory, and finally at Corporate Headquarters. His first assignment at the T J Watson Research laboratory was to find a long life electron emitter to replace the tungsten wire filaments used in electron microscopes at the time. IBM had built the first billion bit computer store using an electron beam to write on photographic film and the relatively short lifetime of the tungsten filament sources was not acceptable. To solve this problem he developed the first practical electron guns that used LaB6 emitters.[8][9] These emitters not only solved the lifetime problem, but also provided higher electron brightness than tungsten filaments, and in the late 1960s and early 1970s he built two new SEMs for examining surfaces that took advantage of this and produced higher resolution than previous SEMs (3 nm in the secondary electron surface mode)[10] and then a short focal length instrument with 0.5 nm beam size.[11] He used the second SEM to examine thin samples in the transmission mode and to examine solid samples using the high energy electron scattered from the surface of the sample, the electrons that had been called 'low-loss electrons by Oliver C Wells who had proposed their use in the SEM. Initially this high resolution low-loss mode was used to examine bacteriophage and blood cells in collaboration with researchers at NYU,[12] and at the Veteran's Administration Hospital in New Jersey[13] however, the bulk of his work was devoted to using the microscopes as tools to scribe things using the lithography techniques that were becoming familiar for making silicon chips. He and his colleague Michael Hatzakis used these new electron beam lithography to make the first silicon transistors with micron dimensions.[14] and sub-micron dimensions showing that it would be possible to scale down the dimensions of electron devices well below the dimensions that were being used at the time.

"I had a marvellous time doing research in the IBM research laboratory" he recalls "I had essentially turned my hobby into my career." He remembers having a roomful of electronics and was overjoyed to spend his time building new things and testing them. There he spent around 16 years in research in one of the best 'playhouses for electronics' in the world, building microscopes and equipment for the fabrication of miniature components. In 1977 he was given the enviable position of being an IBM fellow, an honour accorded to, at that time, only around 40 out of IBM's 40,000 engineers and scientists. This gave him the freedom to follow whatever road of enquiry he wished and he continued his work pushing the limits of what was called at the time microfabrication. Over the next ten years he conducted a series of careful experiments measuring the ultimate resolution of electron beam lithography[15][16][17] and then used the highest resolution methods to fabricate electronic devices.

One of the deleterious effects that limited resolution was the fogging effect of the electrons backscattered from the bulk of the sample. To avoid this Broers and Sedgwick invented a thin membrane substrate using technologies used to make inkjet printer heads.[18] The membrane was thin enough effectively to eliminate the backscattered electrons. These membrane substrates allowed the first metal structures with dimensions below 10 nm to be fabricated and tested.[19] Because these dimensions were now measured in single nanometers he and his coworkers decided to call these nanostructures and the techniques used to make them nanofabrication[20][21] rather than use the prefix micro that had been common parlance until then. Interestingly these membrane samples also found application many years later in MEMs (Micro-Electro-Mechanical) devices, and also as 'cantilevers' in biomedical applications. Early experiments with X-ray lithography[22] also used similar membranes.

When he arrived back in Cambridge, Lord Broers set up a nanofabrication laboratory to extend the technology of miniaturisation to the atomic scale by developing some of the novel fabrication methods[23][24] that he had discovered at IBM. He modified a 400 kV transmission electron microscope (JEOL 4000EX) so that it operated in a scanning mode and produced a minimum beam size of about 0.3 nm. He used this system working in collaboration with researchers at the IMEC microelectronics research laboratory in Leuven, Belgium, to build some of the smallest and fastest field effect transistors that had ever been built.[25]

References

  1. ↑ "List of Fellows".
  2. ↑ Voss, R. F.; Laibowitz, R. B.; Broers, A. N. (1980). "Niobium nanobridge dc SQUID". Applied Physics Letters. 37 (7): 656. doi:10.1063/1.92026.
  3. ↑ Broers, A. N. (1981). "Resolution, overlay, and field size for lithography systems". IEEE Transactions on Electron Devices. 28 (11): 1268. doi:10.1109/T-ED.1981.20599.
  4. ↑ "List of Fellows".
  5. ↑ "List of Fellows".
  6. ↑ "Honorary Fellows - 2003 - Professor Sir Alec Broers". Institution of Mechanical Engineers. Retrieved 16 October 2011.
  7. ↑ Broers, A. N. (1965). "Combined electron and ion beam processes for microelectronics". Microelectronics Reliability. 4: 103. doi:10.1016/0026-2714(65)90267-2.
  8. ↑ Broers, A. N. (1967). "Electron Gun using Long-Life Lanthanum Hexaboride Cathode". Journal of Applied Physics. 38 (4): 1991. doi:10.1063/1.1709807.
  9. ↑ Broers, A. N. (1969). "Some experimental and estimated characteristics of the lanthanum hexaboride rod cathode electron gun". Journal of Physics E: Scientific Instruments. 2 (3): 273. doi:10.1088/0022-3735/2/3/310.
  10. ↑ Broers, A. N. (1969). "A New High Resolution Reflection Scanning Electron Microscope". Review of Scientific Instruments. 40 (8): 1040–5. doi:10.1063/1.1684146. PMID 5797882.
  11. ↑ Broers, A. N. (1973). "High-resolution thermionic cathode scanning transmission electron microscope". Applied Physics Letters. 22 (11): 610. doi:10.1063/1.1654527.
  12. ↑ Broers, A. N.; Panessa, B. J.; Gennaro Jr, J. F. (1975). "High-resolution scanning electron microscopy of bacteriophages 3C and T4". Science. 189 (4203): 637–9. doi:10.1126/science.125922. PMID 125922.
  13. ↑ Trubowitz, S; Broers, A; Pease, R. F. (1970). "Surface ultrastructure of the human marrow--a brief note". Blood. 35 (1): 112–5. PMID 5263118.
  14. ↑ "High Resolution Electron Beam Fabrication", A. N. Broers & M. Hatzakis, Proc. National Electronics Conference, National Electronics Conference, Inc., p. 826–829, 1969 judged best Conference Paper
  15. ↑ Broers, A. N.; Harper, J. M. E.; Molzen, W. W. (1978). "250-Å linewidths with PMMA electron resist". Applied Physics Letters. 33 (5): 392. doi:10.1063/1.90387.
  16. ↑ "Resolution Limits of PMMA Resist for Electron Beam Exposure", 9th Int. Conf. on Electron & Ion Beam Sci. & Technol., Ed. R. Bakish, Electrochemical Soc., Princeton, N.J., p. 396–406, 1980, & J. Electrochem. Soc., 128, p. 166–170, 1980
  17. ↑ Broers, A. N. (1988). "Resolution limits for electron-beam lithography". IBM Journal of Research and Development. 32 (4): 502. doi:10.1147/rd.324.0502.
  18. ↑ Sedgwick, T. O.; Broers, A. N.; Agule, B. J. (1972). "A Novel Method for Fabrication of Ultrafine Metal Lines by Electron Beams". Journal of the Electrochemical Society. 119 (12): 1769. doi:10.1149/1.2404096.
  19. ↑ Broers, A. N.; Molzen, W. W.; Cuomo, J. J.; Wittels, N. D. (1976). "Electron-beam fabrication of 80-Å metal structures". Applied Physics Letters. 29 (9): 596. doi:10.1063/1.89155.
  20. ↑ "Josephson Effect in Nb Nanostructures", R. B. Laibowitz, A. N. Broers, J. T. Yeh, J. M. Viggiano, W. Molzen, Applied Physics Letters, 35, p. 891–893, 1979
  21. ↑ Molzen, W. W. (1979). "Materials and techniques used in nanostructure fabrication". Journal of Vacuum Science and Technology. 16 (2): 269. doi:10.1116/1.569924.
  22. ↑ Feder, R; Spiller, E; Topalian, J; Broers, A. N.; Gudat, W; Panessa, B. J.; Zadunaisky, Z. A.; Sedat, J (1977). "High-resolution soft x-ray microscopy". Science. 197 (4300): 259–60. doi:10.1126/science.406670. PMID 406670.
  23. ↑ Allee, D. R.; Broers, A. N. (1990). "Direct nanometer scale patterning of SiO2 with electron beam irradiation through a sacrificial layer". Applied Physics Letters. 57 (21): 2271. doi:10.1063/1.103909.
  24. ↑ "Electron Beam Lithography—Resolution Limits", Broers, A. N.; Hoole A. C. N. and Ryan J. M.; Microelectronic Engineering 32, pp. 131–142, 1996
  25. ↑ Van Hove, M. (1993). "Scaling behavior of delta-doped Al Ga As/In Ga As high electron mobility transistors with gatelengths down to 60 nm and source-drain gaps down to 230 nm". Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures. 11 (4): 1203. doi:10.1116/1.586921.

External sources

Academic offices
Preceded by
Hermann Bondi		 Master of Churchill College
1990–1996 		Succeeded by
John Boyd
Preceded by
Sir David Williams		 Vice-Chancellor of the University of Cambridge
1996–2003 		Succeeded by
Alison Richard
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