History Corner a Short History: Vacuum Chambers for PVD

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History Corner A Short History: Vacuum Chambers for PVD

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

Introduction (e.g. European Southern Observatory (ESO) which uses magnetron here are many articles and books on vacuum coating [1,2], basic sputter deposition to recoat each of four 8 meter mirrors every 2 vacuum technology [3,4], and materials for vacuum applications years with aluminum [12]). An interesting astronomical mirror but there seems to be little published on the evolution of single and coating system was developed for the MMT (Fred Lawrence multi-chamber vacuum chambers for vacuum coating. he single Whipple Observatory, Tucson, AZ) to coat its 6.5-meter primary chamber system may be as large as a small room (“walk-in”) and the mirror without removing it from the telescope [13]. multi-chamber processing systems may be as long as a football (US) ield (i.e. 100 meters). Some systems may require special design consideration when some chambers are under continuous process gas/vapor low conditions [5] such as used in reactive deposition or low pressure/plasma enhanced chemical vapor deposition processes (LPCVD/PECVD).

Single Chamber Batch Systems In a simple single-chamber “batch” PVD coating system the processing chamber is opened to the ambient ater every deposition. Early vacuum chambers were of glass. Edison’s interest in vacuum technology began in 1878 as it related to his development of the light bulb and its mass production [6]. Edison made industrial use of glass vacuum chambers for sputter deposition of gold on the wax masters for his cylindrical “Gold Moulded” phonograph records beginning in 1892 (Figure 1) [7,8]. Glass (“scientiic glass”) working was an enabling technology for many years in vacuum technology [9].

Figure 1. Edison laboratory for sputter depositing gold on wax masters for “Gold Moulded” cylinder recordings, Berlin 1907. The sputtering belljars are in foreground. Courtesy of the Thomas Edison National Historical Park, Photo #29410084. In the early 1930s PVD began to be used to coat astronomical mirrors with aluminum. his required larger chambers than were Figure 2. Top; John Strong with apparatus for coating the Lick Observatory 36” mirror. World Wide Photos, feasible using glass so metal chambers were developed. he irst 12/12/1933, ID #35054; Bottom: Schematic of deposition apparatus, Figure 13, Ch. IV, “Evaporation and large astronomical mirror to be coated was the 36” Lick telescope sputtering” in Procedures in Experimental Physics, John Strong, Prentice-Hall (1938) mirror (1933) (Fig. 2) [2,10]. In 1947 Strong supervised coating the In 1938 Daniel Wright made the irst “sealed-beam” headlight 200” (5.1-meter) Hale relecting telescope mirror for the Palomar with an incandescent ilament and an internal relector as one Observatory using a 19 foot diameter vacuum chamber and 350 unit [14]. He used a batch coater to coat the relector surface with thermal evaporating ilaments [11]. Today there are facilities that aluminum by ilament evaporation. Wright got the idea from a are capable of coating up to 8-meter diameter mirrors technician who was an amateur astronomer and knew about John

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Strong’s work on aluminizing astronomical mirrors. he irst glass he size, shape and production throughput of single-cycle batch relector substrate was a custard cup from a dime store [15]. he coating systems is determined by the substrate ixturing in the irst sealed-beam headlights using aluminum-coated relectors were chamber. Various designs have been developed to increase the introduced on GM cars in 1941 [16]. number of substrates in the chamber during the processing cycle. In the late 1930s metal chambers were used to deposit zinc hese designs use a magazine loaded with substrates with pick-n- on paper for “self-healing”* paper capacitors using roll-to-roll place tooling*** [16] or a conveyor belt, which could feed substrates (“web coating”, “R2R”) tooling. he zinc deposition process used into the deposition region [32]. In the late 1960s a single-chamber a silver “nucleating” layer [17], which was probably the irst use batch-type system was constructed by the glass irm DELOG of a nucleating layer industrially though the efect of a nucleating (Germany) to produce solar control coatings. he system could layer for Cd had been studied by Langmuir in 1916 [18]. Also in coat a stack (12 panes) of 3m X 4m glass panes using 6 moveable the 1930s the roll-to-roll (R2R) process was used to deposit gold sputtering cathode ixtures to deposit BiOx/Au heat relecting on glassine to make freestanding gold foil, and silver and gold on coatings [33]. Holland reported using sub-stoichiometric Bi2O3 cellophane for decorative use [19-21]. to nucleated gold ilms in 1958 [34]. Gold ilms were used for IR In the late 1950s R2R coating technology was used to make thin relection as well as for window heating elements. foils by depositing a ilm on a continuous band and stripping it of It is interesting to note that many of the early vacuum systems did in the deposition system to form a continuous freestanding foil not use “gate valves” between the difusion pump and the vacuum [24]. his led to the fabrication of thin metal foils by depositing chamber – they “roughed” the system through the difusion pump diicult to fabricate metals, such as beryllium, and titanium alloys as the “dif pump” was heating up [35]. on a mandrel and then removing it in a continuous manner [24]. he 1950s introduced the coating of 3D parts with aluminum for In one design the foil was “rolled-up” external to the deposition decorative purposes (“vacuum metallizing”) [36] using very large system using isolation by cascading “guard vacuums”** (diferential chambers****. Fixturing such as the “rotisserie” and the “Christmas pumping/minimal conductance). tree” ixtures [37] were developed to allow very high substrate During WWII batch coaters were developed for coating lenses loading but were very labor intensive in racking and un-racking. with antirelection (AR) coatings and sighting reticules [16,25] as Later rotating “cage” ixtures were developed to allow 3D parts to be well as R2R coating of paper and plastic with aluminum for radar coated while being tumbled [38-42]. countermeasures (“chaf” – US, “windows” – British, düppel - With the advent of integrated circuit (IC) technology in the German) [20]. Reference 25 is a Record of a Conference held at 1960s and 1970s [43] the need arose for larger capacity systems the Frankford Arsenal in October 1943 [25]. he Record relates which at irst was met by better electron beam evaporation sources the discussions held at that conference and lists companies and [30] and the development of ixtures such as the calotte with 3 individuals involved in the wartime development and production planetary substrate holders [44]. IC technology also led to the of antirelection (AR) coatings on optics in the USA. Reference [26] development of systems to deposit patterned multilayer ilms is a manual for operation of a vacuum coating system as issued in using a compartmentalized single-chamber systems with masks 1945 by the US War Oice. Reference 27 gives some intelligence and a rotatable turret that move the substrates between deposition reports on the activities of the Germans during WW II in optical positions [45]. coatings [27]. Some web and strip roll-to-roll (R2R) coaters require large Plasma cleaning of optical surfaces was developed in the 1930s vacuum chambers for batch processing. Strip coating of steel with [28]. In the early 1970s interest built in having a plasma in the aluminum was started in East Germany in 1971 [46] due to the processing volume while thermally evaporating ilm material for ion high cost of tin used for galvanizing. he strip coating process led to plating [29]. his presented a problem with using the high-voltage very high rate (50 um/s, large area, high volume (50 kg/hr) electron bent-beam electron evaporation source [30] since the electron- beam evaporation of aluminum in very large systems [47]. emitting ilament is at a high negative potential and thus subject to ion bombardment from the plasma. Chambers and Carmichael Multi-Chamber In-Line Systems avoided the problem by separating the vacuum chamber by a plate A step up from the single-chamber batch coater is the multi- containing a valve structure that allowed the chamber to be pumped chamber systems. Multi-chamber systems can take many forms down as one entity. When a plasma was desired in the processing [48]. Oten the chambers are separated by a “guard vacuum” to portion of the chamber the valve was closed leaving the pumping prevent “crosstalk” between processes or environments. port on the portion of the chamber containing the e-beam ilament. he irst multi-chamber vacuum coating system might be that of he only conductance between the two portions of the chamber was homas Edison for his “Gold moulded” process. he gold sputtering then the small hole through which the electron beam passed from cathodes were not actively cooled and so would heat up during use the pumped chamber to the processing chamber [31]. and the radiant heat would harm the wax master. To prevent this *Self-healing is when an arc causes the conductor to “melt-back” thus preventing heating Edison would periodically turn of the sputtering power a short in the capacitor. Self-healing was irst observed using foils rather than metallized paper (“Electrical condenser,” William W. Dean, USP 971,667 *** Fixturing – structure holding substrate(s), usually removable, Tooling – (priority 28 Jan 1909; iled 25 Oct 1909; published 4 Oct 1910). structure holding the ixturing in the vacuum chamber, may have motion (e.g. ** “Guard vacuum” is the term used {e.g. A. Roth, Vacuum Sealing Techniques, planetary motion, “rotisserie” motion, robotic “pick-n-place”). Tool – the whole p. 314, Pergamon Press (1966)} for an actively pumped volume between two system. other volumes and that has a low gas conductance path to each of the volumes **** Stokes Vacuum and Heraeus were leading suppliers of very large (‘walk-in”) that it separates. Guard vacuums may be “cascaded” if the diferential pressure is vacuum deposition chambers – many of their large batch chambers are still in use. high (e.g. processing volume to atmosphere). continued on page 40

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A Short History: Vacuum Chambers for PVD (conductor) and TaN (resistor) ilms****** [52-54] and Ta continued from page 39 (electrolytically anodized) for thin ilm capacitors [55,56]. he MRC (Materials Research Corporation – later a Division of Varian) Series 900 dual-level load-lock sputter-down system (1975) to allow the cathode to cool. To make the process more eicient he and the MRC Series 600 dual-level load-lock horizontal sputter devised a dual chamber system on a single vacuum pumping system deposition in-line system (1980) were two systems irst accepted by where irst one then the other cathode could be sputtered [49]*****. the semiconductor wafer processing industry [57]. Hughes describes a large lock-load system for using the newly Closed-Ended Multi-Chamber Systems developed magnetron sputtering source for depositing a chromium he typical load-lock system has a separate loading chamber where alloy on polymer auto front grills [58]. he system was capable of the substrate holders are pumped down while the processing doing 24 parts per 30-minute cycle. chamber is kept under vacuum. When the loading chamber is at Energy Conversion Devices patented a closed-end roll-to-roll vacuum a valve is opened and the substrates are transferred into the system for coating a lexible substrate with silicon by Plasma processing chamber. Ater the process is over the valve is opened Enhanced Chemical Vapor Deposition (PECVD) in 1981 [59]. his and the substrates moved back into the loading chamber. In some later evolved into an open-ended roll-to-roll system for producing cases there may be separate chambers for loading and unloading the thin ilm solar cells (later). process chamber. An interesting in-line load-lock deposition system was the In 1969 OCLI bought an air-to-air coater called the “Mac” for equipment to coat 10’X12’ panes of glass held vertically using a multi-layer mirror coatings using thermal evaporation. he Mac unique horizontally emitting electron beam evaporators [33,60-62]. coater had a cleaning module integrated with the deposition system Open-ended air-to-air multi-chamber systems so the glass substrate did not have to be manually handled ater An open-ended in-line air-to-air multi-chamber system allows cleaning (Fig. 3) [50]. the continuous introduction of substrates at one end of the line and the continuous output of the coated substrates at the other end. here may be many chambers in-line and chamber isolation may be by valves or by diferential pumping. An early version of the air-to-air in-line system was used to deposit tantalum on ceramics for integrated circuits [63,64]. he irst low-e glass coater for architectural glass (10’ X 12”) was built by AIRCO in 1975/76 [33]. In the 1970s air-to-air strip coaters were introduced [46]. In Europe air-to-air in-line coaters are built to coat “jumbo” glass (6meters×3.21 meters) and “half-jumbo” panes with multi-layer ilms. he open-ended air-to-air system has been very attractive to the

thin ilm solar cell industry which uses (CdZn)S/CuInSe2, CdS/

CdTe, (CdZn)S/Cu2S and microcrystalline silicon as the active layers [65,66]. Energy Conversion Devices (ECD) made an air-to- air pilot line for depositing amorphous silicon solar cells in the early 1980s [67].

Figure 3. A schematic of the OCLI MAC in-line multi-chamber coater with entrance and exit load-locks. With Multi-Chamber Cluster Tool permission of Rolf Illsley, OCLI. Instead of an in-line coniguration the “cluster tool” has the he advent of integrated circuits (IC) [43] the need for multilayer chambers arranged around a central transfer chamber. he Applied ilms and patterning of the layers using deposition masks led to Materials Precision 5000 was the irst commercial cluster tool the development of a multi-chamber system with an entrance/exit for the semiconductor industry (introduced April 1987). It could load-lock with a magazine (24 substrate holders), interconnected handle single wafers up to 200mm diameter with a “pick-and-place” processing chambers (4) with substrate conveyors, heaters, masks, transfer mechanism. his system was used for sequential deposition and continuously pellet-fed evaporation sources (SiO undercoat : of doped and undoped PECVD ilms with an intermediate plasma- cermet {Cr+SiO} resistor : SiO insulator : Cu conductor) [51]. etching step [68]. he throughput requirements of the IC industry led to the development of several types of high throughput in-line multi- Multi-Pass Systems chamber sputter deposition systems for depositing tantalum In Atomic Layer Deposition (ALD) a ilm is grown on a substrate by exposing its surface to alternate gas/vapor species, which react ***** A similar dual chamber arrangement was manufactured by Distillation on the surface [69]. Under the proper conditions the process is Products, Inc. (DPI) of Rochester, NY (later Consolidated Vacuum Corp. {CVC}) (their LC-1-500 system) and was used during WWII for optical coating. ****** It is interesting to note that when developing the Ta:TaN conductor/ heir system did not have isolation (“gate’) valves between the metal difusion resistor IC they tried using the same Ta sputtering cathode for depositing the Ta pumps and the chambers and used water-cooled cold traps to keep oil vapors conductor and then the reactive sputter deposition of the TaN resistor material. from entering the chambers. he system was “roughed down” through the hey found that ater the reactive sputtering it took many hours to remove the difusion pumps as they heated up. {Distillation Products literature (1943) – per TaN formed on the target so they could sputter pure Ta – so they went to two Donald M. Mattox. separate sputtering cathodes/chambers.

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saturated with complete coverage of the surface. To build up a or “feedthrough collar” that allowed introduction of utilities and thickness the substrate must be exposed alternately to the gas/ motion into the vacuum chamber. As metal chambers with sight vapor precursors many times. his may be done by cycling the ports came into use glass chambers disappeared even for chambers atmosphere (precursor1 – purge – precursor2) in one chamber less than 18 inches diameter. (slow) or by passing the substrates through two (or more) isolated Stainless steel chambers containing the precursors (“spatial” ALD). he original Type 304L austenitic stainless steel (18Cr:8Ni, low carbon {L}) ALD process [70] used a rotating planar (disc) ixture between two and type 316L austenitic stainless steel (16.5Cr:2.1Mo, low carbon) vapor beams to produce PbS on a rigid substrate. are generally the preferred metals for vacuum systems because of A multi-pass ALD system has been developed that uses a circular their weldability, resistance to corrosion, and outgassing properties arrangement for the chambers and a rotary substrate carrier that [78,79]. he 18:8 composition was patented in 1924 by W. H. Hatield carries the rigid substrates through the chambers in a circular but was not widely used for vacuum chambers until the 1950s. motion [71]. A similar system has been reported for deposition of Aluminum multilayer optical coatings on polymers using magnetron sputtering Aluminum vacuum chambers came into use as a substitute for and PECVD in guard vacuum isolated chambers. [72]. stainless steel in the early 1980s – aluminum was barely mentioned Dickey has described two coaters for depositing coatings on in pre-1970 books on vacuum technology. he primary aluminum lexible substrates [73,74]. One is a R2R coater and the other is a alloys used are the high purity 1000 and 2000 series and 6061 –T6 a “band” coater. Both systems use 3 vacuum zones. work-hardenable aluminum alloy. Aluminum has good outgassing properties and welds easily with TIG welding. A disadvantage of Big Vacuum Chambers aluminum is that the surface inish can easily be destroyed if the he 1950s and 1960s ushered in the era of big vacuum systems wrong cleaning process is used. for particle accelerators, space simulation******* and later fusion reactors. Although these systems were not used for PVD the Liners and Coatings vacuum technology they engendered is oten applicable to PVD A perennial problem with vacuum chambers for PVD processing systems. is the ilm buildup on the vacuum chamber wall and other non-removable surfaces. his coating buildup can afect the Vacuum Chamber Materials pumping characteristics of the system thus afecting the process In the early days glass chambers suiced but with the need for larger reproducibility. he buildup may lake thus producing particulates chamber to coat astronomical mirrors arose in the mid-1930 metal that give pinholes in the ilm/coating. chambers became necessary. he cold rolled steel plates of that time One approach to the problem is to have removable liners in were porous******** as were the welds********* so liberal use was strategic locations in the chamber. hese liners may be removed made of paint, wax and putty to seal the leaks. and either “stripped” or discarded periodically [80]. A common In the early 1950s as vacuum-based surface science studies discardable liner material is oil-free aluminum foil. Reusable liners (LEED, RHEED, AES, etc.) became more demanding, outgassing are oten made of stainless steel or aluminum and may be bead became an important factor [75] particularly since annealing blasted to reduce laking of the buildup material. became an important factor in producing clean surfaces [76,77]. Another approach is to coat the chamber surface with a material Glass that makes the buildup easy to remove. his may be aluminum

he early glass belljar were made of high thermal expansion (removed with NaOH), molybdenum (removed by H2O2) or glasses (e.g. soda-lime glass) and were prone to crack with uneven carbon, which prevents adhesion. he carbon may be deposited by heating. In 1915 Corning introduced the low-thermal-expansion decomposition of a hydrocarbon in a plasma as is done for fusion borosilicate glass, Pyrex™ that alleviated that problem. he question reactors (see later). of belljar breakage was still a safety question so most glass belljars (as well as other glass envelopes – e.g. ionization gauges) have mesh Demountable Vacuum Seals cages around them. he belljars were formed by molding the glass Early vacuum gasket material was greased leather. It is said that into a mold – and the largest commercial glass belljar seems to be Otto von Guericke used a greased leather seal in his Magdeburg 18 inches in diameter. he glass belljar sat on a metal “baseplate” demonstration in 1656. Greased leather seals as moving gaskets in manual vacuum pumps were used well into the 20th century. ******* he Space Power Facility at NASA Glenn Research Center’s Plum Brook Edison used wax to seal his glass belljars to the baseplates. It is Station in Sandusky, Ohio, houses the world’s largest space-simulation vacuum interesting to note that as late as 1938 [81] wax sealing was used to chamber. It measures 100 feet in diameter and is 122 feet tall. seal glass bell jars to metal base plates. Strong speciies a mixture ******** he Vacuum Induction Melting (VIM) process mostly eliminates the of “beeswax and resin” for sealing the belljar to the baseplate. porosity problem is the steel and is generally speciied for vacuum chamber steel E.F. Northrup built the irst prototype of a vacuum induction furnace in 1920 in Strong does describe some use of rubber (“gum” or natural rubber the United States of America. (History of Induction Heating and Melting, Alfred vulcanized with sulfur) gaskets and advises that if the rubber is Mühlbauer, Vulkan-Verlag (2008) ISBN 978-3-8027-2946-1). exposed to the vacuum then “it is advisable to boil it in a 15 percent *********TIG (Heliarc) welding provided a great advance in vacuum chamber caustic solution (potassium hydroxide or sodium hydroxide) manufacturing by allowing pore-free internal weld to be made easily. Russell to dissolve free sulfur and remove talc from the surface.” Silver Meredith of Northrop Aircrat perfected the TIG process in 1941. Meredith named the process Heliarc because it used a tungsten electrode arc and helium as chloride was also used as a demountable seal material and could a shielding gas, but it is oten referred to as tungsten inert gas welding (TIG). he take higher temperatures than the waxes. American Welding Society’s oicial term is gas tungsten arc welding (GTAW). continued on page 42

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A Short History: Vacuum Chambers for PVD Glow discharge cleaning (GDC) continued from page 41 GDC relies on the fact that a potential is generated between the plasma and surfaces in contact with the plasma (“wall sheath”). If the plasma is of an inert gas such as argon (Ar) positive argon Neoprene (“artiicial”) rubber was introduced in 1933 by E. I. ions are accelerated across the sheath to “ion scrub” the surface. DuPont and molded sealing gaskets of this material began to be If there are reactive reactive gases such as oxygen and hydrogen used by the vacuum industry. For example molded “L” shaped in the plasma they are “activated” by dissociation, excitation and rubber gaskets replaced wax for sealing glass belljars to baseplates. ionization. he “activated gases can react with contaminants to form he “L” gasket has the disadvantage of electrically isolating a metal volatile compounds [28]. belljar from the baseplate – oten Be-Cu “inger” contacts are used Of course glow discharge cleaning had been around since the to electrically connect the belljar and baseplate. mid-1930s to clean optical surfaces [28,95,96] and thus was also In 1957 Viton™ A (E. I. DuPont) luoroelastomer polymer cleaning the vacuum chamber. Lewin (1965) seems to be the irst to was introduced to the aerospace industry and is the preferred discuss GDC as an integral part of vacuum technology instruction elastomer for high temperature (to 200C) and chemically corrosive [97]. Holland discussed the state of the art of GDC in 1976 [98]. applications. Kelrez™ (E. I. DuPont) is a similar product with a he dependence of glow discharge parameters with time was slightly higher operational temperature (to 250C). High vacuum observed by Jurriaanse, Penning, and Moubis, in 1946 and was sealing techniques as of the 1960s were summarized in 1966 by attributed to the release of surface species into the discharge [99]. Alexander Roth [82]. his efect was an important consideration in USP 2,677,071 [100]. Elastomer ‘O” ring seals (the “O” refers to the gasket cross section he irst paper on quantitatively studying conditioning of metal – the gasket itself may be round or other shapes with rounded vacuum surfaces using mass spectrometric techniques was in 1970 corners) are common and are usually itted in a groove on one side [101]. hey found that cleaning of the vacuum surfaces did not of mating surfaces [83]. he O-ring groove and “O” ring dimensions afect the outgassing of metal surfaces. Quantitative measurement determine the compression of the seal which is generally ~30%. of discharge parameters as a function of time as measured against O-rings are oten lightly greased with a vacuum grease to aid in surface composition of a surface being sputter cleaned was done sealing and the same O-ring may be used repeatedly. his groove/O- by Sot X-ray Appearance Potential Spectroscopy (SXAPS) in 1973 ring system is common for large area seals, [102]. he equilibrating of the discharge parameters was used to he KF (Klein Flansche – small langes) sealing system uses establish reproducible sputter deposition conditions [103]. an O-ring held between a centering ring and a retaining O-ring Many surface conditioning studies have been the result of studies (“spacer seal”) [84]. he O-ring system is compressed between of cleaning for fusion reactors including glow discharge cleaning two smooth surfaces (i.e. it is a “sexless” seal). he diameter of with hydrogen [104,105]. It is interesting to note that to keep the the O-ring is greater than the retaining plates therefore when the high-Z contamination level low in fusion reactors the operators surfaces are mated metal-to-metal the compression of the O-ring may deliberately coat the vacuum surfaces with carbon [106] or provides the vacuum seal. he name KF was adopted by ISO and boron [107] prior to each “shot” by plasma dissociation of precursor DIN standards organizations. vapors (i.e. they deliberately “contaminate” the vacuum surface). Single-use metal shear seals may be used in large-area and small- Cleaning with atomic hydrogen may be done without having area seals [85]. Strong describes a lead wire shear/deformation seal a plasma. Reference [108] uses atomic hydrogen formed by a hot in 1938 [86]. Wheeler patented a wire shear/deformation seal in ilament for cleaning surfaces. 1969 [87] as did Bills and Warren in 1967 [88]. he wire seal is oten “Bakeout” called a “Wheeler seal.” he single-use sot metal (Pb, In, Sn, Cu, Al) Heating the vacuum chamber to a high temperature for long wire seal is oten used in ultra-high vacuum systems, particularly periods of time (~72 hours) to desorb and outgas the vacuum ones with large sealing surfaces [89]. surfaces (“bakeout”) became commonplace as Surface Science Another single-use metal seal is the knife-edge seal (1955/1956) investigations required ultra-high vacuum (<10-8 Torr) in the late [90,91]. he CF (originally called ConFlat™ [92]) knife-edge sexless 1950s [75,109]. When using metal seals the bakeout temperature seal is ubiquitous in ultra-high vacuum applications. he seal may be as high as ~450C (the annealing temperature of stainless mechanism is a knife-edge that is machined in a groove below steel). he high-temperature heating is usually done by having a each of the lange’s lat surfaces. As the bolts of a lange-pair are removable oven that surrounds the vacuum chamber and associated tightened, the knife-edges make an annular indentation on each components (the British called it “stoveing”). Temperature side of a single-use sot copper gasket that its in the groove. he uniformity during bakeout is important to prevent contaminants extruded metal ills all the machining marks and surface defects on from condensing in the cooler area. the knife-edge surfaces yielding a leak-tight seal. he “bakeout” is diferent than the warming that is done to the here are many other demountable vacuum sealing designs such chamber walls to minimize moisture absorption. his warming may as the canted spring loaded “C” ring metal gasket and inlatable be done using coils or jackets containing hot water that are aixed to elastomer seals for non-parallel mating surface. the chamber walls or by heater tapes wrapped around the chamber. Double-walled vacuum chambers have been built to allow high “Conditioning” of Vacuum Chambers temperature bakeout of the inner chamber while water cooling an In addition to typical cleaning processes the production of smooth outer chamber [110]. clean metal surfaces by electropolishing and chemical polishing are important to producing good vacuum surfaces [80,93,94].

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19. “History of Vacuum Roll Coating,” John B. Fenn, Jr., Ch. 3, pp16-20 in 50 years of Vacuum Coating Technology and the growth of the Society of Vacuum Coaters, Conclusion edited by Donald M. Mattox and Vivienne Harwood Mattox, SVC (2007) Before the 1930s glass chambers had suiced for vacuum 20. E.O. Dierich, R. Ludwig, and E.K. Hartwig, “Vacuum web coating – An old technology with a high potential for the future,” p. 354-364 in 40th Annual Technical Conference technology. With the advent of aluminum coatings for astronomical Proceedings, Society of Vacuum Coaters (1997) mirrors large metal vacuum chambers were introduced. In the 21. “Process of producing metal emboss,” Cecil Whiley, USP 2,243,237 (filed 26 Sept 1938; early 1940s the invention of the sealed beam headlight for cars published 27 May 1941) 22. “Foil production,” Hugh R. Smith, Jr. USP 3,181,209 (filed 18 Aug 1961; published introduced the need for high throughput vacuum deposition 4 May 1965) (assigned Temescal Metallurgical Corp.) machines. 23. H.R. Smith and C.d’A. Hunt, “Methods of Continuous High Vacuum Strip Processing,” World War II introduced AR coatings for optics, particularly for p. 227 in Transactions of The Vacuum Metallurgy Conference (1964), American Vacuum Society (1964) the Navy. Ater the war the availability of surplus equipment gave 24. H.R. Smith, Jr., K. Kennedy, and F.S. Boericke, “Metallurgical Characteristics of rise to the decorative coating industry. he need for low unit cost Titanium-Alloy Foil Prepared by Electron-Beam Evaporation,” J. Vac. Sci. Technol. 7(6) of decorative coating gave rise to the very large vacuum deposition S48 (1970) 25. “The Application of Metallic Fluoride Reflection Reduction Films to Optical chambers. In the 1960s multilayer integrated circuits gave rise to Elements,” svc.org/HistoryofVacuumCoating/Historical-Papers.cfm in-line multi-chamber systems. 26. “OPERATION AND MAINTENANCE OF OPTICAL COATING EQUIPMENT” (TM 9-1501, A major change in vacuum deposition chamber design came WAR OFFICE 1945), svc.org/HistoryofVacuumCoating/Historical-Papers.cfm with the increasing use of sputter deposition to replace thermal 27. “Optical Thin film technology – Past, present, and future,” William P. Strickland, p. 221 in 33rd Annual Technical Conference Proceedings (1990), Society of Vacuum evaporation in in the 1960s-1970s. Instead of needing a large Coaters (1990) volume chamber to handle ixturing and radiant heating, sputter 28. “A Short History of in situ Cleaning in Vacuum for Physical Vapor Deposition (PVD),” deposition chambers became more compact. Sputtering also made Donald M. Mattox, pp. 50-53 in SVC Bulletin (Fall 2014) 29. D.M. Mattox and G.J. Kominiak, “Structure Modification by Ion Bombardment in-line multi-chambers more feasible. During Deposition,” J. Vac. Sci. Technol. 9, 528 (1972) For multi-chamber systems the addition of PECVD and plasma 30. “Apparatus for producing and direction an electron beam,” Charles W. Hanks, USP etching processing steps added more chambers. he semiconductor 3,535,428 (filed 17 July 1968; published 20 Oct 1970) (assigned to Air Reduction) industry led to the small-footprint cluster tool. 31. D.L. Chambers and D.C. Carmichael, “Development of processing parameters and electron-beam techniques for ion plating,” p. 13 in 14th Annual Technical In the future new technologies such as Atomic Layer deposition Conference Proceedings (1971), Society of Vacuum Coaters (1971) (ALD) will give rise to a whole new family of multi-pass deposition 32. J.G. Needham, “A high capacity vacuum sputtering machine,” Trans. 10th National systems. Vacuum Symposium (1963), pp. 643-650, American Vacuum Society, Macmillan (1964) 33. Hans J. Gläser and B. Szyszka, “History of glass coating for architectural glazing,” pp. 216-229 in 50th Annual technical Conference Proceedings (2007), Society of References Vacuum Coaters (2007); also “History of low-e coatings,” Hans J. Gläser; ___www. interpane.com/interpane2013/m/en/history_of_low-e_coatings_123.87.html 1. “Bibliography: PVD (and related) Books,” compiled by Donald M. Mattox, pp. 33-36, Bulletin, Society of Vacuum Coaters (Fall 2012): also svc.org/publications/ 34. L. Holland and G. Siddall, “Heat-reflecting windows using gold and bismuth oxide Bibliography:______PVD processing – more complete films,” J. Appl. Physics 9, S.359-361 (1958) 2. “50 years of Subatmospheric and Vacuum Technology for Vacuum Coating,” Donald 35. Earle B. Brown, “High vacuum equipment,” p. 35 in Amateur Telescope Making, Vol. 3, M. Mattox, Ch. 12 (p. 86) in 50 Years of Vacuum Coating Technology and the edited by Albert G. Ingalls, Scientific American (1953) Growth of the Society of Vacuum Coaters, edited by Donald M. Mattox and 36. “Decorative Coating” Donald M. Mattox, Ch. 2 in 50 Years of Vacuum Coating Vivienne Harwood Mattox, SVC publications (2007) ISBN 978-1-878068-27-9 Technology and the growth of the Society of Vacuum Coaters, edited by 3. IUVSTA:VSTD Bibliography, Part 1: Textbooks on Vacuum Science and Technology: Donald M. Mattox and Vivienne Harwood Mattox, Society of Vacuum Coaters (2007) http://iuvsta-us.org/iuvsta2/?id=800 37. “Vacuum Technology: Fixtures and tooling,” p. 43 in Education Guides to Vacuum 4. [AVS] AVS Historical Book Collection, Thomas Jefferson National Accelerator Coating Processing, Donald M. Mattox, Society of Vacuum Coaters (2009) Facility (Jefferson Lab): https://www.jlab.org/div_dept/cio/IR/AVS.html ISBN 978-1-878068-28-6 5. Editorial “Expanding the scope of vacuum technology training,” Donald M. Mattox, 38. D.M. Mattox and F.N. Rebarchik, “Sputter Cleaning and Plating Small Parts,” p.6, Bulletin, Society of Vacuum Coaters (Summer 2015) Electrochem. Technol. 6, 374 (1968) 6. R.K. Waits, “Edison’s vacuum technology patents,” J. Vac. Sci. Technol. A 21(4) 881(2003) 39. “Interface formation, adhesion, and Ion Plating,” Donald M. Mattox, Trans. Soc. Auto. Eng. (SAE) 78, 2175 (paper # 690647) (1970) 7. R.K. waits, “Edison’s vacuum coating patents,” J. Vac. Sci. Technol. A 19, 1666 (2001) 40. K.E. Steube and L.E. McCrary, “Thick Ion Vapor Deposited Aluminum Coatings for 8. “Process of Duplicating Phonograms,” Thomas A. Edison, USP # 484,582 (filed 5 Jan Irregular Shaped Aircraft and Spacecraft Parts,” J. Vac. Sci. Technol. 11, 362 (1974) 1888; published 18 Oct 1892) (assigned to Edison Phonograph Company) 41. “Glow discharge coating apparatus,” J. Carpenter, G. Kesler, A. Klein, L. McCrary, and 9. “Fundamental Operations in Laboratory Glass Blowing,” Ch. 1 in Procedures in K. Steube, USP 3,750,623 (filed 11 Feb 1972; published 7 Aug. 1973) (assigned to Experimental Physics, John Strong, Prentice-Hall (1938) McDonnell Douglas Corp.) 10. Ibid., Figure 13, Chapter IV “Evaporation and Sputtering,” p. 173 42. “Glow discharge-tumbling vapor deposition apparatus,” Kenneth E. Steube, USP 11. J.A.F. Trueman, “The design and operation of large telescope mirror aluminizers,” 3,926,147 (filed 15 Nov 1974; published 16 Dec. 1975) (assigned to McDonnell pp. 32-39 in 22nd Annual Technical Conference proceedings, Society of Vacuum Douglas Corp.) Coaters (1979) 43. R.K. Waits, “Evolution of integrated-circuit vacuum processes: 1959-1975,” J. Vac. Sci. 12. www.eso.org/sci/facilities/paranal/telescopes/ut/coating.html; - sputter deposition Technol. A 18(4) 1736 (2000) 13. W. Kindred, J.T. Williams, and D. Clark, “In situ aluminization of the MMT 6.5m 44. Gunard O.B. Mahl, “Thin-film deposition apparatus,” USP 3,643,625 (filed 7 Oct 1968; primary mirror,” MMTO Tech. Report #03-8 (June 2003) – filament evaporation published 22 Feb 1972) (assigned to Carl Herrmann Assoc. {CHA}) sources 45. K. Taylor, “The deposition of composite passive micro-miniature circuits by vacuum 14. “Electric lamp,” Daniel K. Wright, USP 2,148,315 (filed 29 Mar 1938; published evaporation,” p. 981 in Transactions of the 8th National Vacuum Symposium (1961), 21 Feb 1939) (assigned General Electric Corp.) American Vacuum Society, Pergamon Press (1962) 15. Frank Adams, “Vacuum metallizing in the lamp industry,” pp. 46-49 in 23rd Annual 46. S. Schiller, G. Beister, U. Heisig, and H. Foerster, “High-rate vapor deposition and Technical Conference Proceedings, Society of Vacuum Coaters (1980) large systems for coating processes,” J. Vac. Sci. Technol. A 5(4) 2239 (1987) 16. C. Alexander, “Early vacuum systems and processes descriptions used to deposit 47. Ibid optical coatings,” J. Vac. Sci. Technol. A 12(4) 1653 (1994) 48. “In-line Processing Systems,” p. 41 in Education Guides to Vacuum Coating 17. ”The preparation of thin films for electrical purposes: sections 2&3, The zinc coating Processing, Donald M. Mattox, Society of Vacuum Coaters (2009) ISBN 978-1- of capacitor tissue/ Zinc deposition technique” L. Holland, Vacuum Deposition of 878068-28-6 Thin Films, Chapter 8, pp. 252-263 Chapman & Hall (1957) 49. “Apparatus for Vacuously Depositing Metals,” Thomas A. Edison USP #767,216 18. I. Langmuir, “The evaporation, condensation, and reflection of molecules and the (filed 1 Aug. 1903; published, 9 Aug. 1904) (assigned to New Jersey Patent Co.) mechanism of absorption,” Phys. Rev. 8, 149 (1916) continued on page 44

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77. “Preparation, Structural Characterization, and Properties of Atomically Clean A Short History: Vacuum Chambers for PVD Surfaces,” H.E. Farnsworth, (AVS Welch Award presentation) J. Vac. Sci. Technol., 20, continued from page 43 271 (1982) 78. J.R. Young, “Outgassing characteristics of stainless steel and aluminum with different surface treatments,” J. Vac. Sci. Technol. 6(3) 398 (1969) 50. “50 years of subatmospheric and vacuum technology for vacuum coating: Three 79. W.G. Perkins “Permeation and Outgassing of Vacuum Materials,” J. Vac. Sci. Technol. stories from OCLI (Rolf Illsley)” Donald M. Mattox, Ch. 12, pp. 86-95 in 10, 543 (1973) 50 years of Vacuum Coating Technology and the growth of the Society of Vacuum Coaters, edited by Donald M. Mattox and Vivienne Harwood Mattox, SVC 80. “Preparation and cleaning of vacuum surfaces,” Donald M. Mattox, Ch. 4.9, pp. 553-606, (2007) - OCLI “Mac” coater in Handbook of Vacuum Science and Technology, edited by Dorothy M. Hoffman, Bawa Singh, and John H. Thomas, III, Academic Press (1998) 51. W. Himes, B.F. Stout, and R.E. Thun, “Production equipment for thin film circuitry panels,” Transactions of the 9th National Vacuum Symposium (1962), p. 144, 81. Procedures in Experimental Physics, John Strong, p. 160, Fig. 5, Prentice-Hall (1938) American Vacuum Society, Macmillan (1962) 82. Vacuum Sealing Techniques, Alexander Roth, Pergamon Press (1966); also published 52. J.G. Simmons and L.I. Maissel, “Multiple Cathode Sputtering System,” Rev. Sci. as an AVS Classics in Vacuum Science and Technology) (1994) Instrum. 32, 542 (1961) 83. “Sealing techniques,” section 7.3.1 in Vacuum Technology, A. Roth North- Holland (1976) 53. L.I. Maissel and J.H. Vaughn, “Techniques for Sputtering Single and Multilayer Films 84. Ibid. of Uniform Resistivity,” Vacuum, 13, 421 (1963) 85. Ibid. 54. Thin Film Technology, Robert W. Berry, Peter M. Hall, and Murray T. Harris, p. 248, Van Nostrand Reinhold (1968) 86. Ref. [81] p. 128, Fig. 24 55. Ibid., p. 371 87. “Metal Vacuum Joint”, William R. Wheeler, USP 3,458,221 (filed 22 Oct 1965; published 29 July 1969)(assigned to Varian Associates) 56. “Method of making a capacitor employing film-forming metal electrode,” Robert W. Berry (filed 15 June 1958; published 25 July 1961) (assigned to Bell Telephone 88. “Ultra-high vacuum coupling and gasket subassembly thereof,” Daniel G. Bills and Laboratory) Keith A. Warren, USP 3,298,719 (filed 9 May 1966; published 17 Jan 1967) (assigned to Granville Phillips Co.) 57. http://www.chiphistory.org/landmarks.html 89. “Ultra-High Vacuum Flanges” W. R. Wheeler and M. Carlson, p. 1309 in Transactions of 58. L. Hughes, R. Lucariello, and P. Blum, “Production sputter metallization of exterior the Eighth National Vacuum Symposium (1961), American Vacuum Society, plastic automotive parts,” pp. 15-22, 20th Annual Technical Conference Pergamon Press (1962) Proceedings, Society of Vacuum Coaters (1977) 90. P.J. van Heerden, “Metal Gaskets for Demountable Vacuum Systems,” Rev. Sci. 59. “Multiple chamber deposition and isolation system and method,” Vincent D. Instrum. 26, 1131 (1955) Cannella, Masatsugu Izu, and Stephen J. Hudgens, USP 4,438,23 (filed 28 Sept 1981; published 27 Mar 1984) (assigned to Energy Conversion Devices) 91. G.W. Hees, W. Eaton, and J. Lech, “The knife edge seal, Transactions. 2nd American Vacuum Society Symposium, p. 75, Permagon Press (1956) 60. Albany D. Grubb, “The L-O-F semi-continuous thermal evaporation plant; Design and operation of an installation that can deposit up to three thin films on 10 by 12 92. “Metal vacuum joint” Maurice A. Carlson and William R. Wheeler, USP 3,208,758 foot sheets of glass are described,” p.35-39, Research/Development magazine 20(6) (filled 11 Oct 1961; published 28 Sept 1965) (assigned to Varian Associates) (June 1969) 93. “Cleaning techniques,” Ch. 7.2 in Vacuum Technology, A. Roth, North-Holland 61. H.R. Smith, Jr., “High rate horizontally emitting electron beam vapor source,” pp. 49-51 Publishing (1976) in 21st Annual Technical Conference Proceedings, Society of Vacuum Coaters (1978) 94. “Cleaning techniques,” Ch. 9.5 in Methods of Experimental Physics: vol. 14: Vacuum 62. “Centrifugal-type vapor source,” Hugh R. Smith, Jr. USP 3,329,524 (filed 12 June 1963; Physics and Technology, edited by G. L. Weissler and R. W. Carlson, Academic published 4 Jull 1967) (assigned to Temescal Metallurgical Corp.) Press (1979) 63. S.S. Charschan, R,W, Glenn, and H. Westgaard, “A continuous vacuum processing 95. Vacuum Deposition of Thin Films, Leslie Holland, p. 74, Chapman & Hall (1957) machine,” Western Electric Engineer, 7(2) 9-17 (April 1963) 96. Properties of Glass Surfaces, Leslie Holland. Ch. 5, “Cleaning of glass,” Wiley (1964) 64. Sidney S. Charschan and Harald Westgaard, “Apparatus for Processing Materials in a 97. Fundamentals of Vacuum Science and Technology, Gerhard Lewin, Ch. 3, McGraw- Controlled Atmosphere,” U.S. Patent 3,294,670 (filed 7 Oct 1963; published 27 Dec Hill (1965) 1966) (assigned to Western Electric, Co.) 98 L. Holland, “Treating and passivating vacuum systems and components in cold 65. D.M. Mattox, “Solar Energy Materials Preparation Techniques,” J. Vac. Sci. Technol. 12, cathode discharges,” Vacuum 26(3) 97-103 (1976) 1023 (1975) 99. T. Jurriaanse, F.M. Penning, and J.H.A. Moubis, “The normal cathode fall for 66. “Apparatus and method for depositing a material on a substrate,” Ricky C. Powell, molybdenum and zirconium in the rare gases,” Philips Res. Rep. 1(3) 225-238 (1946) Gary L. Dorer, Nicholas A. Reiter, Harold A. McMaster, Steven M. Cox, and 100. “Voltage reference tube,” Gerald G. Carne (filed 30 June 1948; published 27 April Terence D. Kahle, USP 5,945,163 (filed 19 Feb. 1998, published 31 Aug. 1999) (assigned 1954) (assigned to RCA) First Solar, Llc) 101. R.P. Govier and G.M. McCracken, “Gas discharge cleaning of vacuum systems’ J. Vac. 67. “Continuous amorphous solar cell production system,” Masatsugu Izu, Vincent D. Sci. Technol. 7(5) 552 (1970). Cannella, and Stanford R. Ovshinsky, USP 4,410,558 (priority 19 May 1980; filed 16 Mar 1981; published 18 Oct 1983) (assigned to Energy Conversion Devices) 102. J.E. Houston and R.D. Bland, “Relationship between sputter cleaning parameters and surface contaminants,” J. Appl. Physics 44(6) 2504 (1973) 68. Silicon Processing for the VLSI Era: Vol. 1: Process Technology (second edition), S. Wolf and R.N. Tauber, Section 6.2.5.3, Lattice Press (2000) 103. D.M. Mattox, “Fundamentals of ion plating,” J. Vac. Sci. Technol. 10(1) 47 (1973) 69. M. Leskeliä and M. Ritala, “Atomic layer deposition (ALD): From precursor to thin 104. H.F. Dylla, “Glow discharge techniques for conditioning high-vacuum systems,” film structures,” Thin Solid Films 409, 138-146 (2002) J. Vac. Sci. Technol. A 6(3) 1276 (1988) 70. “Method of producing compound thin films,” Tuomo Suntola and Jorma Antson, 105. Surface Conditioning of Vacuum Systems, edited by Robert A. Langley, AVS/AIP USP 4,058,430 (Priority 29 Nov 1974 (Finland); filed 25 Nov 1975; published (1990) 15 Nov 1977) 106. N. Noda, Y. Ogawa, K. Masai, I. Ogawa, R. Ando, S. Hirokura, E. Kako, Y. Taniguchi, 71. E.R. Dickey, W.A. Barrow and B. Aitchison, “Optical coatings by high speed rotary R. Akiyama, and Y. Kawasumi, “Effect of In Situ Carbon Coating on ICRF-Heated spatial ALD,” Paper O-12, 58th Annual Technical Conference Proceedings (2015), Tokamak Plasmas Relating to Radiation Loss by Iron-Impurities in JIPP T-IIU,” Jpn. J. Society of Vacuum Coaters (2015) – in press Appl. Phys. 25 L397 (1986) 72. T. Neubert, J. Lips, R. Bandorf, A. Sabelfeld, M. Vergohl, K. Rohwer, and A. Simon, 107. Nishimura Kiyohiko, Ashikawa Naoko, Sagara Akio, Noda Nobuaki, Kawahata “Deposition of complex optical interference filters on polymer substrates by Kazuo, Morita Shigeru, Byron J. Peterson, Sakakibara Satoru, Takeiri Yasuhiko, magnetron sputtering and PECVD processes,” paper O-11, 58th Annual Technical Tanaka Kenji, Sato Kuninori, Komori Akio and LHD Experimental Group, “Effects Conference Proceedings, Society of Vacuum Coaters (2015) – in press of Boronization in LHD,” J. Plasma Fusion Research, 79(12) 1216-1217 (2003) 73. E.R. Dickey and W.A. Barrow, “High rate roll-to-roll deposition of ALD films on 108. “Cleaning of Metallic surfaces with hydrogen under vacuum,” Karl J. Dietz and flexible substrates,” 52nd Annual Technical Conference Proceedings, Society of Francois Waelbroeck, USP 4,452,642 (priority 19 Oct 1976; filed 22 Oct 1979; Vacuum Coaters, pp. 720-726 (2009) published 5 June 1984) 74. E.R. Dickey and W.A. Barrow, “Single sided ultra-barrier oxide films on flexible 109. Ultrahigh Vacuum and its Applications, Richard W. Roberts and Thomas A. substrates, deposited using high speed atomic layer deposition based on substrate Vanderslice, p.123, Prentice-Hall (1963) translation,” 54th Annual Technical Conference Proceedings, Society of 110. M. Rivera and R. le. Riche,“ A differentially pumped ultra-high vacuum system,” p. 56 Vacuum Coaters, pp. 70-75 (2011) in Vacuum Technology Transactions: Proceedings of the 6th National Symposium 75. Surface Science. The First Thirty Years, edited by C.B. Duke, Elsevier (1994) (1960), American Vacuum Society, Pergamon Press (1960) 76. “Clean Surfaces”, H.E. Farnsworth, p. 21 in Surface Chemistry of Metals and Semiconductors, edited by H.C. Gatos, Wiley and Sons (1960)

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About the Author Donald M. Mattox Don served as a meteorologist and Air Weather Officer in the USAF during and after the Korean War. After being discharged from the USAF he obtained an M.S. degree on the G.I. Bill, and went to work for Sandia National Laboratories in 1961. Don retired in 1989 after 28 years as a Member of the Technical Staff and then as a Technical Supervisor. Don was President of the American Vacuum Society (AVS) in 1985. In 1988, the 9th International Congress on Vacuum Metallurgy presented him with an award for “outstanding contributions to metallurgical coating technology for 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 the Society of Vacuum Coaters (SVC) from 1989 to 2006. In 2007 Don received the Nathaniel Sugerman Award from the SVC. Don is presently the Technical Editor for the SVC. For further information, contact Don Mattox, [email protected].

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