CHAPTER: HISTORY of ION IMPLANTATION in SEMICONDUCTORS
Several of my associates have written review papers on various aspects of the history of ion implantation, or their personal views or experiences associated with aspects of the history of ion implantation. In 1988, I went through my files and collected together all of the old historical material, and organized it by year. In what follows here, I review that material, often in historical time order. This material is certainly not complete, and is not intended to be complete. It is just one person's collection of material that circumstances brought together in one file. It does include some material that has not appeared in the papers and reviews of others referred to above. I apologize to any reader who does not find his or her work referred to here.
Because of the treatment of the history of commercial implantation equipment by A.T. Coughlin, I have chosen not to treat that aspect of the technology, and to include here her work, which has not appeared in the technical literature nor at any of the conferences on Ion Implantation Equipment and Techniques. However, I do treat information regarding research implantation equipment and historical material related to the development of research/technology in sections of this work.
PAPERS that Review Various Historical Aspects of Ion Implantation
L. Wegmann, "Historical perspectives and future trends for ion implantation systems," Nucl. Instrum. Meth. 189, 1-6 (1980)
P.H. Rose, "A history of commercial implantation," Nucl. Instrum. Meth. B6, 1-8 (1985)
J.F. Gibbons, "Historical perspectives on ion implantation," Nucl. Instrum. Meth. B21, 83-89 (1987); see also a section on history in his review paper - "Ion implantation in semiconductors - Part I Range distribution theory and experiments," Proc. IEEE
56, 295-319 (1968).
EARLY PATENTS related to doping semiconductors by ion bombardment or ion implantation:
The strict definition of ion implantation may be interpreted differently by various groups or individuals, depending upon their experience or discipline. As a result of reading some of the early patents, and based on my personal experience in ion implantation, I feel that four significant early patents and their relationship to the technology known today as ion implantation doping of semiconductors are shown in Fig. 1. They are also listed below in more detail, with brief notes about their contents. These four patents are by three originators, Shockley, Ohl, and Moyer. If we consider the subject of ion bombardment as a more general classification, and ion implantation as a subclassification, then the 1949 Shockley patent is relevant, but in that case, the doping effect is caused by damage, not by substitutional impurities resulting from implantation. If we consider doping by atoms of opposite conductivity type rather than damage, then the three patents by Ohl, Moyer, and Shockley become significant. The one by Ohl (1950) is a surface effect, and the two in 1954 by Moyer and by Shockley are for atoms (as ions) "implanted" beneath the surface into the bulk of a semiconductor such that the conductivity type is changed in the implanted region by substitutional placement, which forms a stricter definition of 'ion implantation doping' as known today. 'Ion implantation' has been broadened to include other effects that do not involve doping or conductivity type, for example, materials synthesis, surface modification of metals and ceramics, biology, etc., and so, a broadened definition of 'ion implantation’ could go back in time even before 1949, to include ion bombardment of other surfaces.
W. Shockley, "Semiconductor translating device," US Patent 2,666,814, filed 27 Apr 1949 (issued ?). make p regions in a n layer of Ge using masked ion bombardment by nuclear particles, e.g., 1H, 2H, or 4He plus annealing at 100 to 400°C for minutes to days.
R.S. Ohl, "Semiconductor translating device," US Patent 2,750,541, filed 31 Jan 1950. (issued 12 June 1956) bombardment by ions of a significant impurity to change the conductivity of the surface of a semiconductor body.
J.W. Moyer, "Method of making p-n junction semiconductor unit," US Patent 2,842,466, filed 15 June 1954 (issued 8 July 1958). bombard semiconductor crystal of one type with ions of an activator element of opposite conductivity type, those ions penetrating below the surface where a p-n (or n-p) junction is formed. control of junction depth, doping, and uniformity of "ion implantation".
W. Shockley, "Forming semiconductive devices by ionic bombardment," US Patent 2,787,564, filed 28 Oct 1954 (four months after the Moyer patent was filed) (issued 2 Apr 1957). manufacture of semiconductor devices. implantation of a semiconductor with ions of dopants that cause substitutional doping of opposite conductivity type to the material implanted. B & Ge as example. refers to the related work of Ohl, but notes that Ohl's patent considers change caused on the surface by ion bombardment, while Shockley refers to change caused beneath the surface by "implantation" of the impurity ions (" " my words).
Note also a later patent that speaks to implantation equipment.
W.J. King, "Method of forming a p-n junction by an ionic beam," U.S. Patent 3,388,009, filed 23 June, 1965. uses term "ion implantation" and describes apparatus for implantation, including beam formation, acceleration, mass separation, and scanning.
Early LITERATURE Related to Implanters
Early work that provided a basis for implantation system concepts and components, and for ion implantation itself, in the 1960s, came from work in the areas of particle accelerators (high voltage/energy) and electromagnetic isotope separators (versatile ion beam/element capabilities). Some early work that provided helpful guidance was the doctoral dissertation of O. Almen, "Electromagnetic separation of isotopes in a small laboratory machine," Doktorsavhandlingak vid Chalmers Tekniska Hogskola, Goteborg, 1962, which includes four earlier (1957-1961) papers published in Nucl Instrum 1, 302-322 (1957); 2, 249-260 (1958); 11, 257-278 (1961); and 11, 279-289 (1961). These four works, which include as co-authors, K. O. Nielsen, G. Bruce, and A. Luden, also contributed helpful information regarding sputtering and ion sources. [This work even speaks to ion propulsion (sputtering aspects for lifetime limitations).]
To quote Almen, "Isotope separators are essentially large mass spectrometers." Likewise, ion implanters are mass spectrometers. The industry has developed high current, commercial ion implanters, but when large volume production is not a requirement, a mass spectrometer with microampere currents of all elements serves as an adequate and useful implanter for research. The trade off is versatility and wide range of variables. The implanters at HRL also served as Rutherford backscattering analyzers, performed channeled implantation, performed implants from 5 keV to 1 MeV (lower fluences), provided implants at temperatures from liquid nitrogen to 500°C, implanted at many angles, implanted essentially all elements in the periodic table (with turn around time from 15 to 60 min), provided energy accuracy to within 1%, and implanted one isotope only for all elements over small area (~ 1 inch) and one isotope only over 4-inch areas up to about mass 100, and two isotopes over 4-inch areas from 100 to 200 m/z.
1957 July 10 K.O. Nielsen, "The development of magnetic ion sources for an electromagnetic isotope separator," Nucl. Instrum. 1, 289-301 (1957)
1961 Aug 30 R.W. Barnfield, B.W. Farmery, L.C.W. Hobbis, R.S. Nelson, and M. W. Thompson, "A 100-keV heavy ion accelerator for the study of irradiation damage," Plasma Physics 4, 89-93 (1962).
BOOKS About or Related to Ion Implantation
Ion implantation in semiconductors: silicon and germanium, J.W. Mayer, L. Eriksson, & J.A. Davies [Academic Press, 1970]
Ion implantation, G. Dearnaley, J.H. Freeman, R.S. Nelson, & J. Stephen [North Holland, 1973]
Ion beams; with application to semiconductors, R.G. Wilson & G.R.. Brewer [Wiley, 1973]
Channeling: theory, observation, and applications, Ed. D. V. Morgan [Wiley, 1973]
Applied solid state science, Advances in material and device research, Vol. 5, K. A. Pickar [Academic Press, 1975]
Ion beam handbook for material analysis, J.W. Mayer & E. Rimini
[Academic Press, 1977]
Ion implantation, H. Ryssel & I. Ruge [Wiley, 1986]
The stopping and ranges of ions in matter, 5 Volumes Ed. J.F. Ziegler [Pergamon]
Handbook of semiconductors, Vol. 3, Ed. S.P. Keller [North Holland, 1980] e.g., J.F. Gibbons, p. 599.
REVIEWS that Relate to Ion Implantation
1969 L.N. Large, "Ion implantation: a new method of doping semiconductors - I," Contemp. Phys. 10, 277-98 (1969). Interesting feature of this paper is the use of balls for
ions, and pin arrays for a lattice the generation of depth distributions by rolling balls through the lattice in different orientations.
1969 G. Dearnaley, K. Kandiah, & R.S. Nelson, "Ion implantation in semiconductors," Phys. Bull. 20, 165-68 (1969)
1976 J.H. Freeman, "The boundaries of ion implantation," Inst. Phys. Conf. Ser. 28, chapter 9, 340-56 (1976)
PAPERS, REPORTS, and PRESS RELEASES Related to Ion Implantation or Depth Distributions of Ions in Crystals or Materials - from 1960 to 1977
1960 Nov 3 J.A. Davies & G.A. Sims, "The range of 24Na ions of kiloelectron volt energies in aluminum," Can. J. Chem. 39, 601-10(1961) Ranges and profiles.
1961 Jan 10, F.M. Rourke, J.C. Sheffield, and F.A. White, "Crystal "doping" by ion bombardment," Rev. Sci. Instrum. 32, 455-56 (1961)
1962 Aug 2 O.S. Oen, D.K. Holmes, & M.T. Robinson, "Ranges of energetic atoms in solids," J. Appl. Phys. 34, 302-10 (1963) Monte Carlo calculations.
1962 Dec 5 M.T. Robinson & O.S. Oen, "The channeling of energetic atoms in crystal lattices," Appl. Phys. Lett. 2, 30-32 (1963)
1962-65 Ion Physics Corp. Reports on AF contracts AF33(657)-10505 and AF33(615)-2292
1963 Feb 22 J.A. Davies, F. Brown, & M. McCargo," Can. J. Phys. 41, 829
1963 Mar 20 C. Lehmann & G. Leibfried, "Long-range channeling effects in irradiated crystals," J. Appl. Phys. 34, 2821-36 (1963)
1963 June 6 J.H. Ormrod & H.E .Duckworth, "Stopping cross section in carbon for low energy atoms with Z < 12," Can. J. Phys. 41, 1424-42 (1963)
1963 July 29 M.T. Robinson & O.S. Oen, "Computer studies of the slowing down of energetic atoms in crystals," Phys. Rev. 132, 2385-98 (1963)
1963 J.O. McCaldin, & A.E. Widmer, "Silicon heavily doped by energetic cesium ions," J. Phys. Chem. Solids 24, 1073-80 (1963)
1964 Mar 26 M. Waldner & P.E. McQuaid, "Characteristics of silicon p-n junctions formed by sodium and cesium ion bombardment," Solid State Electronics 7, 925-31 (1964); & "In drift effect in silicon p-n junctions formed by sodium ion bombardment," Proc. IEEE 54, 1966-67 (1966)
1964 Apr 21 P.V. Pavlov, E.I. Zorin, D.I. Tetel'baum, & Yu.S. Popov, "The depth of penetration and the distribution of radiation defects in germanium bombarded by argon
and nitrogen ions," Sov. Phys.-Solid State 6, 2577-80 (1965)
1964 May 11 B. Domeij, F. Brown, J.A. Davies, & M. McCargo, "Ranges of heavy ions in amorphous oxides," Can. J. Phys. 42, 1624-34 (1964)
1964 Ion Physics Corp., "p-n junction formation techniques," Final Report Contract AF33(615)-1097
1965 In 1965, a series of papers appeared in Nuclear Instruments Methods 38, which comprise the proceedings of the International Conference on "Electromagnetic Isotope Separators and Related Ion Accelerators and their Application to Physics," held in Aarhus, Denmark on 14-18 Jan 1965. Those papers include:
K.J. Hill & R.S. Nelson, "A sputtering ion source," p. 15-18, a versatile mA ion source for metals and gases.
G. Sidenius, "The high temperature hollow cathode ion source," p.19-22
J.H. Freeman, "Isotope contamination and electromagnetic separator performance," p. 49- 55, discusses self and cross contamination in ion sources that relates to implantation
J.H. Freeman, "Some perspectives in electromagnetic isotope separation," p. 97-102, discusses future requirements for applications
J.O. McCaldin, "Ion beams and solid state physics," p. 153-64, work for Li & Na in Si and general discussion.
J.F. Gibbons, J. L. Moll, & N. I. Meyer, "Doping of semiconductors by ion bombardment," p. 165-68, Tm & Nd in Si, GaAs, CdS, and ZnS.
K.E. Manchester, C. B. Sibley, & G. Alton, "Doping of silicon by ion implantation," p. 169-74, B & P in Si, activation efficiency, junction depth, damage - of diodes
D.B. Medved, J. P. Perel, H. J. Daly, & G. P. Rolik, "Implantation and channeling effects of alkali ion beams in semiconductors," p. 175-77, K and Cs beams, 1-20 keV (alkalis do not activate)
W.J. King, J. T. Burrill, S. Harrison, F. Martin, & C. Kellett, "Experience in fabricating semiconductor devices using ion implantation techniques," p. 178-79, 50-400 keV. B & P in Si to make solar cells, radiation detectors, unipolar FETs, and bipolar transistors. channeling discussed. double implants of B & P for bipolars, and single implants through SiO2 passivation layers for FETs
The work at Ion Physics Corp was also described in a press release in Electronics News, June 28, 1965, in which they discussed production work, yields, and future business aspects of implantation.
P. Baruch and J. C. Pfister, "Radiation induced diffusion in silicon," p. 197, proton or electron irradiation at high temperature
1965 Apr 3 P. V. Pavlov, E.I .Zorin, D.I.Telel'baum, E.K. Granitsyna, "The electrical conductivity of inversion layers formed in n-silicon by bombardment with boron ions," Sov. Phys. - Solid State 7, 2386-90 (1966)
1965 June 6 P.V. Pavlov, E.I. Zorin, D.I. Tetel'baum, & Yu. S. Popov, "Donor properties of nitrogen introduced into silicon and germanium by ion bombardment," Sov. Phys.- Doklady 10, 786-87 (1966)
1965 Nov 29 J.F. Gibbons, A. El-Hoshy, K.E. Manchester, & F.L. Vogel, "Implantation profiles for 40-keV phosphorus in silicon substrates," Appl. Phys. Lett. 8, 46-48 (1966)
1965 H.H. Andersen & P. Sigmund, "Defect structures in channeling experiments," Nucl. Instrum. Meth. 38, 1238 (1965)
1965 The potentials of implantation in 1965 were reviewed in an editorial in SCP and Solid State Technology, August, 1965, p.21, which included doping vesatility, room temperature processing, SiC and diamond device potential, doping through SiO2 layers, IC fabrication, writing circuits using tiny ion beams, metallic interconnects fabrication, and flexibility. The limitations of damage, sputtering, and possibly cost, were also mentioned.
1966 Feb 3 P.V. Pavlov, D.I. Tetel'baum, E.I. Zorin, & V.I. Alekseev, "Distribution of implanted atoms and radiation defects in the ion bombardment of silicon (Monte Carlo calculation method)," Sov Phys-Solid State 8, 2141-46 (1967)