History Corner a Short History: Magnetron Sputter Deposition

Home , Sputter deposition

History Corner A Short History: Magnetron Sputter Deposition

Donald M. Mattox, Management Plus, Inc., Albuquerque, NM Contributed Technical Article

any of the studies on the efect of magnetic ields on In the Penning’s cylindrical cathode the electrons are lost at the Melectrons in vacuum were done in developing vacuum gauges ends of the cathode. By adding langes (“wings”) to the ends of the beginning in about 1898 [0]. Devices that use magnetic ields to post (“spool” design) the electrons can be further conined to the control the motion of electrons are called magnetrons. GE coined cathode surface. In another coniguration the cylinder is made the the term magnetron in the early 1920s when they were studying the cathode while the post (or end plates) is the anode (“inverted” or use of magnetic ields instead of grids in electron tubes because of hollow-cathode magnetron). he sputtering then takes place from the vulnerability of their patent position on grid-controlled electron the interior surface of the cylinder. Interior langes on the ends of tubes [1]. the cylinder help conine the electrons. In the mid-1930s Berkhardt and Reineke patented a means of Much of the early work on developing the post magnetron increasing the ionization of atoms thermally evaporated into a sputtering conigurations for ilm deposition was done by Allan plasma at low pressure [2]. hey used a magnetic ield parallel Penfold and John hornton at Telic Corporation in the early to the electric ield between the source (anode or ground) and 1970s [10]. More recent work has been done by David Glocker, the substrate (cathode). his was the irst attempt to cause post- particularly on the inverted magnetron designs [11]. A variation of vaporization ionization in PVD processing. heir patent was the inverted-cylindrical coniguration uses a conical shaped cathode assigned to Bernhard Berghaus, who had a patent on an early (“S-gun”) with an anode at the small end [12**,13]. version of “Ion Plating” using both thermal evaporation [3] and Penning’s 1939 patent also discussed the use of a DC magnetron sputtering [4]. he work of Berghaus was not pursued apparently sputtering in what is now called a “sputter ion pump” a type of from the lack of interest in what are now called “metallurgical “getter” or ”capture” pump where the sputter deposited ilm is used coatings.” Burghaus did pursue the work that he and Arthur to react with reactive gases and to “bury” inert gases [14]. Ion Rudolph Berthold Wehnelt had done on what is now called pumps were the irst large commercial use of magnetron sputter “ionitriding” (German patent 668,532 {1932})*. (Ionitriding, deposited ilms. here were many early developments in the sputter and other plasma surface treatments are used in duplex coatings ion pump including W.F. Westendorp and Anatole M. Gurewitsch, involving PVD [5,6].) USP 2,755,014 (1953), L.D. Hall USP 2,993,638 (1961), and In 1939 F.M. Penning patented the deposition of material by Wolfgang Knauer USP 3,216,652 (1965). sputtering (he called it “cathode disintegration”) using a cylindrical Knauer’s patent is interesting in that he used permanent magnets magnetron coniguration (“Penning cell”) with designs where the inside the post cathode to give an emerging/re-entry magnetic ield magnetic ield was both parallel and perpendicular to the cathode that produced closed electron paths (rings) around the post cathode surface [7,8]. In one coniguration the cathode is a rod (or post) (“closed-ield”). Knauer also described a planar magnetron, which centered in a cylinder (anode), and the magnetic ield was parallel created a closed circular plasma path (washer-shaped) on a planar to the rod and was thus perpendicular to the electric ield (i.e. post surface for sputtering (Fig. 2 of his patent) [15,16]. Knauer studied cathode or cylindrical magnetron sputtering design). he motion the sputter erosion path on a planar surface in a Penning cell [17]. of the electrons emitted from the cathode was such that they (Eric Kay wrote a seminal paper on magnetic ield efects on glow circled the cathode as they moved toward the ends of the rod due discharges as understood in 1963 [18].) to drit normal to the EXB plane. he conining of the electrons DC diode magnetron sputtering conigurations using emerging/ and increased their path length and increased the current density re-entering magnetic ields on the cathode surface began to be and as Penning said “ made the pressure appear to be higher” (as important in PVD ilm deposition in the early 1970s. Mullaly (DOE compared to the current without the magnetic ield). Sputtering DOW Chemical Rocky Flats Plant {RFP}) used a hemispherical takes place from the surface of the post. Penning noted that the quadrapole magnetic ield coniguration to sputter from the “cathode particles disintegrated combine with gas molecules and interior surface of a hemispherical cathode [19]. John Chapin thus bring about a reduction in pressure.” Penning pointed out that (Vacuum Technology Associates (VTA)***) took the hemispherical the establishing and maintaining of a glow discharge was due to the coniguration elongated it into a trough shape and then lattened coninement of the electrons by the magnetic ield [9]. it out to give a “closed ield” planar magnetron using permanent magnets. his magnetron design gave an elongated “racetrack” of *In 1939 Berghaus led Nazi Germany and went to Switzerland carrying all his plasma on the planar surface created by the electron drit normal research notes. Apparently he never tried to patent, publish or commercialize to the EXB plane [20]. his work was done under a development his knowledge on PVD. Berghaus died in the early 1960’s and the Klockner contract with Airco, which led to prolonged litigation over the Group AG of West Germany bought his research notes from his estate. he West German government funded an R&D program into plasma-surface interactions ***Chapin had worked at the Rocky Flat (RFP) DOE facility and was one of that led to the further development of plasma nitriding (“ionitriding”) that is those who let RFP to form Vacuum Technology Associates (VTA). Mullaly’s widely used to hardened metal surfaces. work at RFP was probably not patented since all work done at GOCO ** Note: On Peter Clarke’s patent the name is spelled Clark, which has been the laboratories was in the pubic domain at that time (Donald M. Mattox, SVC source of some erroneous references. Bulletin Editorial “Patent Law redux” [Spring 2011]).

42 | SVC Bulletin Summer 2015

manufacturing/sales rights between Airco and VTA [21]. Chapin’s material utilization [e.g. 46-51] but the most efective uses a rotating patent application was preceded by one from Corbani [22] but cylindrical (tube) source [52,53], which may be used in a MF dual Chapin was able to “swear behind” Corbani’s claim based on an magnetron coniguration. A problem with the rotating cylindrical entry in his laboratory notebook witnessed by Bob Cormia (Airco). magnetron source is that some materials are diicult to form into he DC elongated closed-ield planar magnetron sputter long tubes that are structurally sound. deposition source revolutionized Web Coating [23], Large Area “Open drit” magnetron sputtering sources have been Rigid coating [24] and the coating of temperature-sensitive constructed where the magnetic ield is parallel to the surface over materials particularly the decorative coating of polymer auto front the whole surface area and there is no closed magnetic ield on the grilles with a chromium alloy [25]. he magnetron source had sputtering target surface [54,55]. In this coniguration the plasma a very interesting application for in situ, in-line sputter cleaning may be enhanced by electron emission from an electron-emitting of strip metal in roll-to-roll coating [26]. In Europe a magnetron ilament along one edge of the planar surface [56]. coniguration called the “Ring Gap Discharge” began to be he common planar magnetron utilizes secondary electrons developed and commercialized in the mid-1970s [27, 28]. Multiple from the cathode to sustain the plasma. Injecting electrons from “ring gap” sources could be arranged in diferent conigurations to other sources into the plasma may be used to increase the plasma give linear sources or large-area sources. density. Such electron sources may be from hot ilaments [0,56] or Using the emerging/re-entering magnetic closed ield magnetic hollow cathodes [57]. here also have been magnetron designs that “tunnel” electrons can be efectively trapped in a small volume. are intended to create post vaporization ionization of the vaporized In 1986 Windows and Savvides recognized importance of letting material (iPVD) [58,59] but these designs have been negated by some of the electrons escape and thus creating a plasma in the the development of High Power Impulse Magnetron Sputtering volume outside the tunnel [29]. his plasma region “activates” (HIPIMS), which inherently gives a high degree of ionization of the reactive gases/vapors and acts as a source of ions for energetic ion vaporized material. bombardment of the depositing coating material – they called this High Power Impulse Magnetron Sputtering (HIPIMS) utilizes coniguration an “unbalanced (UB) magnetron” coniguration. very high power densities of >1kWcm−2 in short pulses (impulses) Multiple UB magnetrons may be magnetically linked to form even of tens of microseconds at low duty cycle (on/of time ratio) of < larger plasma volumes [30,31]. 10% [60-63]. A distinguishing feature of HIPIMS is the high degree DC magnetron sputtering works well with targets that are of ionization of the vaporized material (“self-ions”). Ions of the electrical conductors but doesn’t work with electrical insulators. By vaporized material are efective in sputter cleaning the substrate applying an rf (13.56 MHz) to the cathode, insulators such as SiO2 surface and for modifying the surface by subplanting atoms of

[32] and Al2O3 [33] may be sputtered. Rf magnetron sputtering has the coating material into the surface prior to the deposition of the largely been replaced by reactive sputter deposition except for some coating [64]. his is similar to the arc bonded sputtering (ABS) cases of insulating materials with complex compositions. system where by changing the magnetic ield coniguration the Reactive sputter deposition involves sputtering from an elemental magnetron sputtering source can be converted into a streered arc (e.g. Ti), alloy (e.g. Ti:Al), or other electrically conductive (e.g. ITO) vaporization source [65]. target and reacting with a reactive gas (e.g. nitrogen, oxygen) or he length of the HIPIMS pulse is determined by that needed with a co-deposited material (e.g. carbon, boron) on the substrate to prevent the transition of the discharge from a glow to an arc surface. Major advances in reactive sputter deposition came with condition on pulsing. he peak power and the duty cycle are techniques to control the partial pressures of the reactive gas selected so as to maintain an average cathode power similar to (optical emission spectroscopy {OES} and diferentially pumped conventional DC diode sputtering (1–10 Wcm−2) to allow eicient mass spectrometry) in order to limit the “poisioning” of the target cooling. Various pulse shapes have been reported for generating the surface and the attendant reduction in sputtering rate [34-38]. A pulse power for HIPIMS [66]. problem with reactive sputtering is arcing on the target surface he high degree of ionization of the vaporized material in from the “poisoning” by reaction. his can be overcome using rf or HIPIMS has reignited interest the role of “self-sputtering” by mid-frequency (MF - 50-250kHz) pulsed bipolar power supplies “self-ions” of the vaporized material in sputtering process and [39-41]****. in the sputter deposition process [67]. In addition to the surface Dual closed-ield magnetron sources may be electrically linked preparation prior to the coating formation these “self-ions” can in a mid-frequency AC coniguration so that the magnetron play an important role in tailoring the ilm/coating properties by surfaces can alternately act as cathodes and anodes to minimize the energetic particle bombardment of the depositing material during “disappearing anode efect” in reactive sputter deposition processes the deposition process. he “self-ions” are particularly suited for due to coating of the anode by a depositing insulating layer [42-44]. transferring momentum to the deposited surface atoms since they (Non-magnetron low frequency (60Hz) dual cathode AC sputtering have matching AMUs. was discussed in 1971 [45].) One disadvantage of the closed ield planar magnetron sputtering Conclusion coniguration is the low material utilization outside the tunnel Magnetron sputtering is a rather mature technology [63,68] that “racetrack.” Various designs have been proposed to increase has revolutionized the vacuum coating industry and has been an enabling technology in many areas such as tool coating, low-e **** It should be noted that generally pulsed mono-polar DC really has an coatings on architectural glass, and deposition of compounds on asymmetrical AC waveform since the inductance and capacitance in the circuit many thermally sensitive polymers at commercially viable unit discharges giving a current pulse of opposite polarity during the “of” period. continued on page 44

Summer 2015 SVC Bulletin | 43

A Short History: Magnetron Sputter Deposition 5. D.M. Mattox, “Surface effects on the growth, adhesion, and properties of reactively continued from page 43 deposited hard coatings,” Surf. Coat. Technol. 81(1) 8 (1996) 6. M.D. Zlatanović, “Combined plasma surface treatments for wear and corrosion protection,” Tribology in Industry, 25(3-4) 65-70 (2003) cost. he magnetron sputtering process itself is still not completely 7. “Coating by cathode disintegration,” Francis Michael Penning, USP 2,146,025 (priority, understood as exempliied by the presentation [69]: Dec. 28, 1935 {Netherlands}; filed Nov. 7, 1936; published Feb. 7, 1939]) “Magnetron Sputtering: An Uninished Journey” 8. F.M. Penning, “Die Glimmentladung Bei Niedrigem Druck Zwischen Koaxialen Zylindern in Einem Axialen Magnetfeld,” (“The glow discharge at low pressure André Anders, LBNL between coaxial cylinders in an axial magnetic field“) Physica 3(9) 873 (1936) Abstract 9. F.M. Penning and K. Neinhuis, “Construction and application of a new design “Cathode disintegration, as sputtering was originally called, has its of the Philips vacuum gauge,” Philips Tech. Rev. 11, 116 (1949) 10. “Cylindrical magnetron sputtering”, John A. Thornton and Alan S. Penfold, Ch. II-2 in humble beginnings in the 19th century with ingenious inventions Thin Film Processes, edited by John L. Vossen and Werner Kern, Academic closely related to generating electrical power and establishing Press (1978) “empty space,” vacuum. We celebrate Geissler and his glass 11. D.A. Glocker, M.M. Romach and V. W. Lindberg, “Recent developments in inverted cylindrical magnetron sputtering,” Surf. Coat. Technol., 146/147, 457 (2001) chambers, Ruhmkorf’s induction coil, and Grove’s observation 12. “Sputtering apparatus,” Peter J. Clark(e), USP 3,616,450 (priority, Nov.7, 1968; filed, of coatings next to a cathode tip (1852), followed by Wright’s Nov.7, 1968; published, Oct. 26, 1971)** systematic fabrication of thin ilms (1877). Paving the way in the 13. “The Sputter and S-Gun magnetrons,” David B. Fraser, Ch. II-3 in Thin Film Processes, 1930s for later breakthroughs, Penning described the trapping edited by John L. Vossen and Werner Kern, Academic Press (1978) 14. Lewis D. Hall, “Ionic vacuum pumps,” Science 128(3319) 279 (1958) of electrons in certain electric and magnetic ield conigurations, 15. “Ionic vacuum pump,” Wolfgang Knauer, USP 3,216,652 (filed, Sept. 10, 1962; concepts leading to the development of our modern magnetrons in published, Nov. 9, 1965) the 1970s (Chapin, Clarke, Penfold and hornton). his, however, 16. W. Knauer and E.R. Stack, “Alternative ion pump configurations derived from a more thorough understanding of the Penning Discharge,” p. 180 in 1963 Transactions Natl. was just the beginning of an incredible success story that afects Vac. Symp. (10th), American Vacuum Society (1964) everybody’s life today as magnetron sputter deposition enabled 17. W. Knauer, “Mechanism of the Penning discharge at low pressures,” J. Appl. Physics a wide range of product developments. Diferent magnetron 33(6) 2093 (1962) geometries (planar, rectangular, cylindrical), scaling, rotating 18. Eric Kay, “Magnetic field effects on an abnormal truncated glow discharge and their relation to sputtered thin-film growth,” J. Appl. Phys. 34(4) 700 (1963) targets, dual magnetrons, and magnetrons in hybrid conigurations 19. J.R. Mullaly, “A crossed-field discharge device for high rate sputtering,” RFP-1310 (Nov. with other discharges expanded the availability and variety of 13, 1969) – available on the SVC website under: SVC/History of Vacuum Coating/ coatings. Plasma transport and thin ilm growth theories laid the Historical papers/#6; also R&D magazine p. 40 (February 1971) 20. “Sputtering process and apparatus,” John S. Chapin, USP 4,166,018 (filed, Jan 31, basis for optimization. Pulsing at radio-frequency (rf) made the use 1974; published, Aug. 28, 1979) of insulating targets possible, and medium frequency (mf) pulsing, 21. “597 F. 2d 220 – Inc v. Airco Inc.”; openjurist.org/597/f2d/220/inc-v-airco-inc fast gas feedback loops, and fast arc suppression circuits were major 22. ”Cathode sputtering apparatus,” John F. Corbani, USP 3,878,085 (filed, July 5, 1973; advancements to minimize unwanted arcing, especially for reactive published, April 15, 1975) 23. “History of vacuum roll coating,” John B. Fenn, Ch. 3 (p. 16) in 50 Years of Vacuum deposition conditions (early 1990s). Magnetic unbalancing brought Coating Technology and the growth of the Society of Vacuum Coaters, edited by plasma assistance to the deposition process (1980s), and pulsing Donald M. Mattox and Vivienne Harwood Mattox, SVC (2007) at extreme peak power densities introduced plasma-deposition by 24. “History of large area coatings,” Russell J. Hill, Ch. 4 (p. 21) in 50 Years of Vacuum Coating Technology and the growth of the Society of Vacuum Coaters, edited by HiPIMS and HiPIMS-like processes at the turn of the millennium. Donald M. Mattox and Vivienne Harwood Mattox, SVC (2007) Yet, there are surprising features to be discovered, explained, and 25. L. Hughes, R. Lucariello, and P. Blum, “Production sputter metallization of exterior exploited, such as the recent (2012) observations of traveling plastic automotive parts,” p. 15, 20th Annual Technical Conference of the Society of Vacuum Coaters (1977) ionization zones or “spokes”, which have profound inluence on 26. S. Schiller, U. Heisig, and K. Steinfelder,” A new sputter cleaning system for metallic magnetron operation and particle luxes to the substrate. he substrates,” Thin Solid Films 33, 331 (1976) journey in the world of magnetron sputter deposition is far from 27. S. Schiller, U.Heisig, and K. Goedicke, “On the use of ring gap discharges for high-rate inished, which becomes abundantly clear when looking at its vacuum coating,” J. Vac. Sci. Technol. 14(3) 815 (1977) 28. “40 Years of Industrial Magnetron Sputtering in Europe,” U. Seyfert, J. Strümpfel, history in a time lapse format.” ***** U, Heisig and J. Hartung, paper L-6 (invited) Society of Vacuum Coaters 58th Annual Technical Conference (2015) ***** Andre Anders calls Kouznetsov’s paper (1999) [61] a seminal paper that 29. B. Windows and N. Savvides, “Unbalanced magnetrons as sources of high ion fluxes,” began the era of HIPIMS because it was not the irst to report high voltage J. Vac. Sci. Technol. A4(3) 453 (1986) sputtering and “self-sputtering” [69]. (For example: N. Hosokawa, T. Tsukade, 30. D.G. Teer, “Technical Note: A magnetron sputter ion-plating system,” Surf. Coat. and T. Misumi, “Self-sputtering phenomena in high-rate coaxial cylindrical Technol. 39-40, 565 (1989) magnetron sputtering,” J. Vac. Sci. Technol. 14, 143 (1977)) 31. “Magnetron sputter ion plating,” Dennis G. Teer, USP 5,556,519 (priority date, May 17, 1990 {UK}, filing date Mar. 17, 1994; publication, Sept. 17, 1996) 32. R.S. Nowicki, “Properties of rf-sputtered films deposited by planar magnetron,” J. Vac. References Sci. Technol. 14, 127 (1977) 0. V.W. Gaede, “Tiefdruck Messungen” (low pressure measurements) Zeitschr. F. Techn. 33. L.D. Hartsough and P.S. McLeod, “High rate Al2O3 sputtering of enhanced aluminum Physik 12, 664 (1934) - vacuum gauge review paper mirrors,” J. Vac. Sci. Technol. 14, 123 (1977) 1. James E. Brittain, “The Magnetron and the beginnings of the microwave age,” Physics 34. C.D. Tsiogas, J.N. Avaritsiotis, and C.A. Kagarakis, “Practical aspects for the use of Today, pp. 60-68 (July 1995) plasma emission monitoring in reactive sputtering processes,” Vacuum, 45(12) 1181 2. “Method of coating articles by vaporized coating materials,” Rudolf Reinecke and (1994) Wilhelm Berkhardt, USP 2,157,478 (priority {Germany}, June 7, 1936, filed 35. W.D. Sproul, “High rate reactive sputtering process control,” Surf. Coat. Technol. 33, 74 June 15, 1937; published, May 9, 1939) (1987) 3. “Improvements in and relating to the coating of articles by means of thermally 36. “Method for sputtering compounds on a substrate,” William D. Sproul and Michael E. vaporized materials,” Bernhard Berghaus, U.K. Patent 510,993 (1938) Graham, US Patent 5,942,089 (filed, April 22, 1996; published, Aug. 24, 1999) 4. “Coating of articles by cathode disintegration,” Bernhard Berghaus and Wilhelm 37. W.D. Sproul, D.J. Christie, and D.C. Carter, “Control of reactive sputtering processes,” Burkhardt, USP 2,305,758 (priority {Germany}, May 25, 1937; filed, April 22, 1938; Thin Solid Films 491, 1 (2005) published, Dec. 22, 1942)

44 | SVC Bulletin Summer 2015

38. “System and method for feedforward control in thin film coating processes,” Craves 68. “Magnetron Sputtering,” G. Bräuer, Ch. 4.03, p. 57 in Films and Coatings: Technology Evan and George Mark, US Patent 7232406 B2 (priority, Oct. 8, 2003; filed, Oct.8, and Recent Developments, Vol. 4, (volume editor David Cameron) in the series 2004; published, April 21, 2005) Comprehensive Materials Processing (13 volumes) editor-in chief M.S.J. Hashmi, Elsevier (2014) 39. G. Brauer, J. Szczyrbowski, and G. Teschner, “Mid frequency sputtering – a novel tool for large area coating,” Surf. Coat. Technol. 94/95, 658 (1997) 69. “Magnetron Sputtering: An Unfinished Journey,” André Anders, Donald M. Mattox tutorial presentation, 58th Annual Technical Conference of the Society of Vacuum 40. “Low frequency, pulsed, bipolar power supply for a plasma chamber,” Gunter Mark, Coaters (April, 2015): available as an audio recording synchronized with the USP 5,303,139 (priority, July 31, 1991; filed, July 30, 1992; published, April 12, 1994) PowerPoint presentation on the SVC website, www.svc.org. 41. ”Pulsed direct current power supply configurations for generating plasmas,” Richard A. Scholl and David J. Christie, USP 5,917,286 (filed, May 8, 1996; published July 29, 1999) About the Author 42. Fazle S. Quazi, “Method and apparatus for sputtering a dielectric target or for reactive sputtering,” USP 4,693,805 (filed, Feb. 1986; published, Sept. 15, 1987) Donald M. Mattox Don served as a meteorologist and Air Weather Officer in 43. G. Estes and W.D. Westwood,” A Quasi-direct-current sputtering technique for the deposition of dielectrics at enhanced rates,” J. Vac. Sci. Technol. A6(3) 1845 (1988) the USAF during and after the Korean War. After being 44. David A. Glocker and Mark Romach, “System for unbalanced magnetron sputtering discharged from the USAF he obtained an M.S. degree with AC power,” USP 6,733,642 (priority, April 30, 2001; filed, April 29, 2002; on the G.I. Bill, and went to work for Sandia National published, May11, 2004) Laboratories in 1961. Don retired in 1989 after 28 years as 45. Henry Y. Kumagal, “Sputtering method and apparatus,” USP 3,616,402 (filed, May 31, a Member of the Technical Staff and then as a Technical 1968; published, Oct. 26, 1971) Supervisor. Don was President of the American Vacuum Society (AVS) in 1985. In 46. “Kathodenzerstäubungsvorrichtung” (“Cathode sputtering device” with magnetic 1988, the 9th International Congress on Vacuum Metallurgy presented him with equipment which can be displaced to move the area of sputtering over an extended an award for “outstanding contributions to metallurgical coating technology for surface by relative movement) John F. Corbani, DE 2,707,144 A1 (Germany) (priority Feb. 19, 1976; filed, Feb. 18, 1977; published Aug. 25, 1977) – moving magnet the period 1961-1988” and in 1995 he was the recipient of the AVS Albert Nerken Award for his work on the ion plating process. Don was the Technical Director of 47. “Planar magnetron sputtering device,” C.B. Garrett, USP 4,444,643 (priority 3 Sep. 1982; filed 16 June 1983; published 24 April 1984) – moving magnet the Society of Vacuum Coaters (SVC) from 1989 to 2006. In 2007 Don received the 48. Michael Geisler, Joerg Kieser, and Reiner Kukla,, “Zerstäubungskatode nach dem Nathaniel Sugerman Award from the SVC. Don is presently the Technical Editor magnetronprinzip” (“A sputtering cathode according to the magnetron”) DE for the SVC. 3,527,626 (Germany) (filed Aug.1,1985, published Feb. 5, 1987) – Inter-pole-target For further information, contact Don Mattox, [email protected].______49. “Magnetron sputtering cathode,” Richard P. Welty USP 4,865,708 (filed Nov. 14, 1988; published Sept. 12, 1989) – shunts in magnetic system 50. “Permanent magnetic structure for use in a sputtering magnetron,” Richard E. Stelter, USP 5,865,970 A (filed, Feb. 23, 1996; published, Feb. 2, 1999) 51. Auxiliary in-plane magnet inside a nested unbalanced magnetron,” Tza-Jing Gung, USP 6,495,009 (filed Aug. 7, 2001; published Dec., 2002) – moving magnet 52. “Magnetron cathode sputtering apparatus,” Harold E. McKelvey, USP 4,356,073 (priority, Feb. 12, 1981; filed Feb. 12, 1981; published, Oct. 26, 1982); also “Magnetron cathode sputtering apparatus,” Harold E. McKelvey, USP 4,422,916 (priority, Feb. 12, 1981; filed, Feb. 11, 1982; published, Dec. 27, 1983) 53. R. De Gryse, J. Haemers, W.P. Leroy, and D. Depla, “Thirty years of rotatable magnetrons,” Thin Solid Films 520, 5833 (2012) – review paper 54. D. Glocker and M. Romach, “Open drift magnetron cathodes,” 57th Annual Technical Conference Proceedings, Society of Vacuum Coaters, pp. 440-444, SVC (2014) 55. “Method and apparatus for linear magnetron sputtering,” John Marshall, III, USP 5,298,137 (priority, April 19, 1991; filed, Oct,1, 1992; published, Mar. 29, 1994 56. “Integrated sputtering apparatus and method,” P.R. Fournier, USP 4,155,825 (filed, May 2, 1977; published May 22, 1979) 57. J.J. Cuomo and S.M. Rossnagel, “Hollow cathode-enhanced magnetron sputtering,” J. Vac. Sci. Technol. A4, 393 (1986) 58. S.M. Rossnagel and J. Hopwood, Appl. Physics Lett. 63, 3285 (1993) 59. Ionized Physical Vapor Deposition, edited by J.A. Hopwood, Academic Press (2000) 60. “Method and apparatus for magnetically enhanced sputtering,” Vladimir Kouznetsov, US Patent 6,296,742 (priority, Mar. 11, 1997; filed, Sept. 10, 1999; published, Oct. 2, 2001) 61. V. Kouznetsov, K. Macak, J. Schneider, U. Helmersson, and I. Petrov, “A novel pulsed magnetron sputter technique utilizing very high target power densities,” Surface Coat. Technol. 122 (2–3) 290 (1999) 62. A.P. Ehiasarian, R. New, W.-D. Munz, L. Hultman, U. Helmersson, and V. Kouznetsov, “Influence of high power densities on the composition of pulsed magnetron plasmas,” Vacuum 65 (2) 147 (2002) 63. “High Power Impulse Magnetron Sputtering – HIPIMS,” R. Bandorf, V. Sittinger, and G. Bräuer, Ch. 4.04, p. 75 in Films and Coatings: Technology and Recent Developments, Vol. 4, (volume editor David Cameron) in the series Comprehensive Materials Processing (13 vol.) editor-in chief M.S.J. Hashmi, Elsevier (2014) 64. A.P. Ehiasarian, J.G. Wen, and I. Petrov, “Interface microstructure engineering by high power impulse magnetron sputtering for the enhancement of adhesion,” J. Appl. Phys., 10(5) 054301 (2007) 65. W.-D. Munz, D. Schulze, and F.J.M. Hauser, “A new method for hard coating: ABS (arc bond sputtering),” Surf. Coat. Technol. 50(2) 169 (1992) 66. e.g. Roman Chistyakov and Bassam Abraham, “Advanced Pulsed DC Technology for Material Processing Applications: Part 1. Methods of Generation of High Power Pulsed Magnetron Discharge,” p. 46, Bulletin, Society of Vacuum Coaters (Spring 2009)

67. A. Anders, “Deposition rates of high power impulse magnetron sputtering: Physics ______and economics,” J. Vac. Sci. Technol. A28(4) 783 (2010)

Summer 2015 SVC Bulletin | 45