US3379819A

US3379819A - Electron gun for evaporating or sublimating material in a vacuum environment

Info

Publication number: US3379819A
Application number: US579678A
Authority: US
Inventors: Adelore L Houde
Original assignee: FILMTECH ASSOCIATES Inc
Current assignee: FILMTECH ASSOCIATES Inc
Priority date: 1966-09-15
Filing date: 1966-09-15
Publication date: 1968-04-23
Anticipated expiration: 1985-04-23

Description

219- 121 MTRM 3,379,819 ATING MEHT A. L. HOUDE HON GUN FOR EVAPORATING OR SUBLIM 4 Sheets-Sheet 1 I N V E NTOR. 4.051%; A. Ham;

wry/m6? A. 1.. HOUDE 3,379,819 ELECTRON GUN FOR EVAPORATING OR SUBLIMATING MATERIAL IN A VACUUM ENVIRONMENT 4 Sheets-Sheet 2 April 23 ,1968

Filed Sept. 15, 1966 INVENTOR.

April 23, 1968 A. L HOUDE 3,379,819

ELECTRON GUN FOH EVAPORATING OR SUBLIMATING MATERIAL IN A VACUUM ENVIRONMENT Filed Sept. 15, 1966 4 Sheets-Sheet 5 April 23, 1968 A. HOUDE 3,379,819

ELECTRON GUN FOR BV APORATING OR SUBLIMATING MATERIAL IN A VACUUMIENVIRONMENT Filed Sept. 15, 1966 4 Sheets-Sheet 4 United States Patent Ofiice 3,379,819 Patented Apr. 23, 1968 3,379,819 ELECTRON GUN FOR EVAPORATING R SUBLIMATING MATERIAL IN A VACU- UM ENVIRONMENT Adelore L. Houde, Garden Grove, Calif., assignor to Filmtech Associates, Inc., Garden Grove, Calif., a corporation of California Filed Sept. 15, 1966, Ser. No. 579,678 12 Claims. (Cl. 1331) This invention relates to electron guns of the type used in evaporating or sublimating materials for microelectronic thin film devices.

Electron guns are used for the evaporation or sublimation of source or evaporant material in a vacuum environment. The evaporated material is typically applied to form thin films on substrates. Thin film deposition of various materials on substrates finds application in microelectronic devices and in such fields as magnetics and optical filters.

Electron guns operate on the theory of electron emission from a filament or other source of electrons. A source material to be evaporated or Sublimated is placed in electron communication with a source of electrons and bombarded. The bombardment causes the materials evaporation or sublimation. To aid in evaporation, electrons are accelerated from their source to the evaporant material by a large voltage gradient which is established between the two.

It is desirable for an electron gun to be able to evaporate as many materials as possible in order to accommodate the many applications presented to thin film technology. Thus, an electron gun should be capable of evaporating such evaporants as metals, alloys, dielectrics and semi-conductors at a satisfactory and controllable rate. Moreover, in many thin film applications it is desirable to evaporate different materials at the same time to produce a blend of the different materials. Alternately, different distinct films of different material may be desired on the same substrate. In the latter instance, it would be highly desirable to produce the different film without disrupting the vacuum environment in which deposition takes place. In other words, if the vacuum environment were destroyed for each material deposited on given substrate, which would be required if the electron gun had to be recharged with different evaporant materials, total production time and deposition cost would be materially increased. Even if a common evaporant were to be used on a given application, it may be desirable to evaporate a large quantity of the material from a single loading of the electron gun. Because of the different applications and materials to be evaporated, an electron gun having the capacity to evaporate materials in many forms is a very versatile instrument; thus, evaporant material should be able to be evaporated when it is in rod, wire, ribbon, granular or powder form.

The vacuum environment in which material deposition normally takes place is within a bell jar. Bell jars are connected to a base plate through a feed-through ring or collar. A versatile electron gun, then, should be adapted for use with a conventional feed-through collar. In addition, provision against contamination of the electron guns electron source enhances the reliability, accuracy, and operating time of the electron gun; accordingly, shielding of the electron source is desirable.

It is to the accommodation of the above criteria that the instant invention is directed. In general, the electron gun of the present invention includes a body, at least one electron source assembly carried by the body, an evaporant assembly carried by the body and capable of holding a plurality of evaporant materials, and means for selectively positioning the evaporant assembly with respect to the electron source assembly to present a given evaporant material thereto. The body is adapted to be mounted on the outside of a vacuum chamber, such as a bell jar, preferably on a conventional feed-through ring. The electron source assembly is adapted to mount at least one filament which acts as a source of electrons. The evaporant assembly is adapted to mount a plurality of spaced-apart evaporant materials, which may be similar or dissimilar, in position to cooperate with a filament mounted in the electron source assembly for the electron bombardment of a given one of the evaporant materials. The means for selectively positioning the evaporant assembly with respect to the electron source assembly allows a choice of which of the evaporant materials will be presented for evaporation. The electron source assembly and the evaporant assembly are adapted for placement within the vacuum chamber.

In preferred form, the electron gun of the present invention contemplates an evaporant assembly composed of a plurality of tandemly disposed turrets. Each of the turrets has provision for the mounting of evaporant materials at regular intervals about its radial periphery. The turrets, as an assembly, are secured to a cylindrical support member which extends into and through an axial cylindrical bore in the body. The body member has a mounting collar or flange disposed in position for mounting on a conventional feed-through collar and a cylindrical portion extending normal to the mounting collar. Disposed about the outer radial surface of the cylindrical portion of the body member are a plurality of longitudinal grooves. These grooves are spaced apart to correspond to the distance between evaporant materials mounted on a given turret. A barrel is coaxially mounted around the cylindrical portion of the body such that it is capable of rotational and translational movement with respect to the body. The barrel contains a detent which provides a positive locking action when it encounters one of the longitudinal grooves. The locking action is overcome by simply rotating the barrel with respect to the body until a new groove is found. The barrel is keyed to the support member such that the latters movement is mirrored by the movement of the barrel. Translational positioning of evaporant materials mounted on the turrets is readily accomplished through the provision of a plurality of spaced-apart circumferential grooves On the inner cylindrical surface of the barrel. A lug operable from outside the vacuum chamber is placed in the body for selective engagement with the circumferential slots. These slots are spaced to correspond to the translational position of evaporant materials mounted on the turrets. Thus by simply moving the barrel with respect to the body in both translation and rotation, the position of the evaporant materials disposed about the radial periphery of the turrets can be adjusted. The locking provided in both translation and rotation occurs only when evaporant material is in proper relationship with the electron source assembly for evaporation.

The electron source assemby of the preferred embodiment of the instant invention includes a filament housing. The filament housing is adapted to contain at least one filament in electron communication with an electron chamber disposed within the housing. The electron chamber is capable of being positioned such that an evaporant material mounted on a turret can extend into the chamber. The filament housing is carried by a yoke assembly which is carried by the body and adapted to extend within the vacuum chamber. In order to facilitate the positioning of evaporant material with respect to the electron source assembly, the latter is pivotally mounted to the body to allow the clearance of evaporant material from the electron chamber when it is desired to place a new evaporant material within the chamber. This pivotal action is accomplished through a handle mounted on the outside of the body and connected to the yoke assembly.

Among the advantages inherent in the instant electron gun is the facility for mounting a great number of evaporant materials within a vacuum chamber together with the ease of placing any one of these evaporant materials in position for its evaporation or sublimation. This facility allows a broad range of evaporants to be used without disrupting the vacuum environment of deposition. If the electron gun is adapted with more than one electron source assembly, blending of evaporant materials is possible. Moreover, because of the large number of evaporant materials which can be mounted on the electron guns evaporant assembly and readily positioned with respect to the electron source assembly, a large amount of material can be evaporated without destroying the vacuum in the vacuum chamber. In addition, a broad selection of evaporant materials is possible which may take any number of forms such as rod, ribbon, wire, granular or powdered, and still be effectively evaporated by the instant electron gun because of the ease of mounting such materials on or to the evaporant assembly. The electron gun can be readily used with existing feed-through rings and bell jars. Moreover, filament shielding is effectively and simply accomplished as will be apparent subsequently.

These and other features, aspects and advantages of the instant invention will become more apparent from the following description and drawings, in which:

FIGURE 1 is an abbreviated plan view, partly in section, of a preferred embodiment of the instant invention;

FIGURE 2 is an elevational view in section taken along lines 2-2 of FIGURE 1;

FIGURE 3 is an end view of the embodiment shown in FIGURE 1 taken along lines 3-3;

FIGURE 4 is a side view of the embodiment shown in FIGURE 1 taken along lines 4-4;

FIGURE 5 is an end view of the embodiment shown in FIGURE 1 taken along lines 5-5; and

FIGURE 6 is an electrical schematic of the power system which may be used with the illustrated embodiment of the instant invention.

Referring now to the figures, there is seen the preferred electron gun 1 of the instant invention. The electron gun I is adapted to be mounted on a feed-through collar 2 of standard, commercially available design for use with, for example, a vacuum bell jar (not shown). Mounting is conveniently accomplished through the provision of a rectangular mounting collar or flange 3 with a plurality of fastener-receiving holes 156. An O-ring 4 is disposed in flange 3 to provide a seal against the feed-through ring. In general, the interior of the vacuum bell jar will see yoke assembly '31, filament assembly support 36, filament assemblies 43 and 46, and evaporant material assembly 92. In use, the outside of the vacuum system will see the body 8 together with attendant positioning structure which will be described subsequently.

Yoke assembly 31 is pivotally mounted to body 8 through shaft 6 and yoke securing pin 28. Shaft 6 is journaled in body 8 in bore 73 and has a pair of annularly disposed O-rings 7 which serve as seals. On the outside of shaft 6 is mounted a positioning lever assembly 5 which is used for pivoting yoke assembly 31 and its carried structure. As seen in FIGURE 3, positioning lever 5 comprises an arm 150 which is permanently secured to body 8 and rotatably receives shaft 6. Movable arm 151 is secured to shaft 6 and acts as a lever for turning shaft 6 and tilting yoke assembly 31. Tension spring 152 is attached to lever 151 through spring keeper 153 at one of its ends and to permanent arm 150 at its other end. Spring 152 serves to urge the shaft 6 to the position which keeps yoke assembly 31 disposed in its proper relationship with respect to evaporant assembly 92 when evaporation is desired. This position is shown in FIGURE 2. Shaft 6 is connected to arm 64 of yoke assembly 31 through pin 69 which is received between the tines of fork 68 formed at the end of shaft 6. Seals 7, as well as other seals to be described, are pumped down through ducts 155 which are in vacuum communication with shaft 6 and water jacket 16. Fittings for the pump-down equipment can be conveniently placed in female threads 154. Yoke securing pin 28 is threaded in body 8 and has a narrow portion which extends into bore 72 for pivotal receipt by arm 29 of yoke assembly 31. Arm 64 as well as arm 29 are received in body 8 in rectangular slots 66 and 71. These arms pass through feed-through collar 2 through its opening 65. Yoke assembly 31 includes an annular flange 33 which is connected to retaining ring 35 by fasteners 32 and insulators 34.

Retaining ring 35 is electrically insulated from flange 33 by electrical insulators 34 to avoid grounding of the electrical circuit used to create electron emission for evaporating evaporant materials mounted in evaporant assembly 92. The yoke assembly 31 has an open interior 70 in order to accommodate water jacket and support member 16 which is disposed coaxially with yoke 31 in body 8.

Filament assembly support 36 in general comprises a pair of arms 62 and 38 which are connected to retaining ring 35 by

fasteners

63 and 39. Arms 62 and 38 support filament assembly 43 by a dowel connection with the filament assemblys bosses 42. Insulator mounting member 37 is held in plaw by arms 62 and 38 and supports electrical insulators 40 and 61 as well as

terminals

41 and 60.

Filament assembly 43 as well as its associated assembly 46 are carried by filament assembly support 36 and ultimately yoke assembly 31. In use, only one filament assembly such as that shown by reference numeral 43 in FIGURE 2 may be desired. On the other hand, additional filament assemblies may be required which are merely added in back-to-back fasihon as shown by the attached assemblies 43 and 46 in FIGURE 1. Filament assembly 43 includes mounting bosses 42 which are secured to arms 62 and 38. Depending from these bosses is the main body portion 50 which contains filament bores 56 and 52, electron chamber and filaments 51 and 57. Filament bores 56 and 52 contain filaments 51 and 57 which act as a source of electrons. Undercuts 53 and 58 communicate the filaments with electron chamber 55 which is centrally disposed within main body portion 50. Each of the filaments are retained in place in filament assembly 43 as shown. The undercuts 53 and 58 have floors 54 and 59 which serve to shield filaments 51 and 57 from evaporant materials. In like fashion filament assembly 46 includes bosses 48 from which depends the mian body portion 45 of the filament assembly. Centrally disposed within assembly 46 is an electron chamber 49. To insure adequate shielding for the filaments contained within each of the assemblies, a shield similar to that shown by reference numeral 47 in FIGURES 1 and 2 is mounted on top of each of the assemblies. For purposes of clarity, one of the shields has been omitted from FIGURE 1. The shield serves to completely enclose the filaments, except to their associated electron chambers, from evaporant material.

Body 8 is adapted to be mounted on the outside of the feed-through collar or ring 2 and has an annular O-ring to seal the interior of the vacuum system from the exterior environment. Cylindrical portion 11 of body 8 depends normally from mounting flange 3 and has an axial bore for receiving water jacket and support member 16. Coaxially disposed about cylindrical portion 11 is barrel 9. Barrel 9 is disposed to rotate about cylindrical portion 11 as well as translate along its length.

Translational positioning and locking of evaporant assembly 92 with respect to filament assembly 43 is accomplished by barrel 9. The interior cylindrical surface of barrel 9 contains a plurality of annular spaced-apart slots 12. Each slot corresponds to the position of one of the turrets of evaporant material assembly 92. Lug shaft 24 is keyed to lug 21 which has an engaging rib 22 sized to fit into each of the slots 12 and to lock the barrel 9 relative to the body 8 and, as will become apparent, evaporant assembly 92 with respect to filament assembly 43.

Spring 23, which is retained in transverse bore 159 in cylindrical portion 11 of body 8, urges lug 21 against the inside cylindrical surface of barrel 9. Shaft 24 is keyed to positioning arm 27 by pin 26. Stop pin 157 is mounted in cylindrical portion 11 of body 8 to contact the edges of hole 158 of lug 21 to properly position the lug in either its locked or unlocked state. Freeing barrel 9 for translational movement is accomplished by simply moving arm 27 in a clockwise direction which releases rib 22 from any one of the slots 12.

Translation of evaporant material assembly 92 follows similar movement of barrel 9 by virtue of the latters connection to water jacket and support member 16 by pin 13. Pin 13 passes transversely through closing piece 14 to its terminus in annular V-shaped groove 18 in plug and manifold piece 17.

Rotational positioning of evaporant material assembly 92 with respect to filament assembly 43 is accomplished by the connection of barrel 9 to water jacket 16 by pin 13. Correct rotational positioning is produced by a plurality of longitudinal peripheral grooves 129 in cylinder portion 11 of body 8. Each of the grooves 129 corresponds in position to one of the evaporant material sockets in the turrets of evaporant material assembly 92 when such socket is coaxially disposed within electron chamber 55 of filament assembly 43. Rotational locking is secured through detent ball 128 which is disposed in locking cooperation with one of the grooves 129. Detent ball 128 is urged into one of the grooves 129 or the surface of cylindrical portion 11 by spring 127. Spring 127 is held in place by set screw 125 which is secured in barrel 9. Detent ball 128 can be forced out of one of the grooves 129 by rotating the barrel 9. Upon finding a different one of the grooves 129, the barrel as Well as the evaporant assembly 92 will be locked in a new position.

Water jacket 16 serves as a supporting member for evaporant assembly 92 and is coaxially disposed for rotation and translation within body 8. Annular seals 67 and 25, mounted in body 8, are in contact with the peripheral cylindrical surface of water jacket 16 to insure the vacuum integrity of the vacuum enclosure. Jacket 16 is capped by plug and manifold piece 17 which is rotatably secured within the bore of jacket 16. The annular groove 18 allows movement of jacket 16 with barrel 9 through pin 13 without disturbing the rotational position of plug 17. Plug 17 is rotatably positioned in jacket 16 and is sealed therein by O-ring 15. Thus, complicated water manifolding is avoided and simple manifolding can be provided through coolant inlet fitting threads 130 and coolant outlet fitting threads 132. Coolant inlet is provided through duct 131 and bore 104 in coolant distribution tube 20. Coolant distribution tube 20 is secured to plug 17 and opens into inlet coolant bore 105 in cylindrical plug 106 at its other end. Cylindrical plug 106 is rotatably mounted in jacket 16 and is sealed through the provision of annular O-

rings

109 and 110. Bore 105 is in coolant communication with coolant nozzles 112 which are radially disposed in distribution tube 116. Coolant outlet is provided through return ooolant passages 103 and 107, the interior of jacket 16 outside of distribution tube 20, and coolant duct 133 in plug 17.

As shown in FIGURE 2, the evaporant assembly 92 preferably comprises a plurality of tandemly-connected turrets. Each turret will have a cooperating annular groove or slot 12 in barrel 9 for its translational positioning and locking with respect to one of the filament assemblies. Turret 100 is connected to jacket 16 by set screws 102 and 108 such that it mirrors the movement of jacket 16 produced by barrel 9. The interior of turret 100 includes an annular coolant groove 99 which is in the direct path of coolant being discharged through nozzles 112. A plurality of evaporant sockets or recesses, such as those shown by reference numerals 98 and 114 are disposed about the radial periphery of turret 100. Each of these recesses is capable of accepting and securing a source of evaporant material such as that shown in red form by reference numeral 113 contained within evaporant socket or recess 114. Turret 93 is connected to turret and has an annular coolant groove 95, an annular coolant bore 96, as well as a plurality of evaporant sockets such as those shown by reference numerals 94 and 115. Closing piece 90 is threaded to turret 93 and sealed by O-ring 91 to prevent the passage of coolant into the interior of the vacuum system. Each of the evaporant sockets of each of the turrets has a cooperating longitudinal groove 129 on the cylindrical portion of body 8 for its correct radial positioning relative to the evaporant assemblies. In addition, the evaporant sockets of each turret are radially aligned with corresponding sockets in other turrets in order that proper radial positioning of evaporant materials with respect to the filament assemblies can be accomplished by a common one of the longitudinal grooves 129.

The electrical system preferred for dual evaporation with the electron gun 1 of the instant invention is shown schematically in FIGURE 6. This system envisions the use of low voltage alternating current for heating the filaments. Superimposed on the alternating current is a negative voltage which is applied to the filaments to create a large voltage gradient between the evaporant materials and the filaments. This gradient is possible because the evaporant assembly is at ground potential while the electron emitting filaments contained within the filament assemblies are at a high negative voltage. The differential in voltage, then, will accomplish a direction of electrons to evaporant materials contained on the evaporant assembly and disposed within the electron chambers of the filament assemblies to cause their evaporation or sublimation.

Alternating current source is connected to primary winding 171 of transformer 173. The secondary winding 172 of transformer 173 is connected at one of its ends to junction 183. The other end of secondary winding 172 is in series circuit with

filaments

174 and 175 and meets the first end of secondary winding 172. at junction 183. A complementary alternating current power source 186 is connected to primary winding 185 of transformer 187. The secondary winding 184 of transformer 187 is connected at one of its ends to junction 183 and is serially connected at its other end to

filaments

177 and 178. The alternating current circuit of transformer 187 is completed through junctions 176 and 181 at junction 183. Thus, the secondary windings of

transformers

173 and 187 are tied at junction 183. A high voltage source 179 has its positive terminal 182 connected to ground while its negative terminal 180 is connected to junction 181. Junction 181 is connected to junction 176 and thus

filaments

177, 178, 174 and 175 are in circuit with high voltage source 179 through

secondary windings

172 and 184 to junction 183.

The circuit illustrated in FIGURE 6 would be applied to the electron gun 1 shown in FIGURE 1 as follows:

Filaments

174 and 175 would correspond to filaments 51 and 57. The circuit between filaments 51 and 57 is completed by main body portion 50 of filament assembly 43. Either of the

terminals

41 or 60 would correspond to junction 176 while the other terminal would carry the lead to secondary 172.

Filaments

177 and 178 would be secured in filament assembly 46. Filament 178 would be connected to the terminal corresponding to junction 176 while filament 177 would be connected directly to secondary winding 184.

If only one filament assembly is desired, one of the alternating current power supplies would be eliminated from the circuit shown in FIGURE 6. In this case, filaments 51 and 57 of FIGURE 1 would correspond to

filaments

174 and 175 of FIGURE 6. The serial connection between these two filaments is provided by the main body portion 50 of filament assembly 43. One of the

terminals

41 or 60 would be connected to secondary winding 172 and each would be connected to one of the filaments. The other of the

terminals

41 or 60 would be connected to high voltage source 179 and to the other end of secondary winding 172.

In use, the electron gun I is mounted on feed-through ring 2 after any of a number of selected evaporant materials inserted in the evaporant sockets, such as are shown on FIGURE 2 by reference numerals 98, 94, 115 and 114. These evaporant materials maybe of similar or dissimilar materials. The vacuum environment for evaporation or sublimation is then secured. A selected one of the evaporants is positioned relative to the filament assembly 43 such that it extends into the electron chamber 55 for electron communication with filaments 51 and 57. The evaporant so disposed is then subjected to electron bombardment for any desired purpose.

If another evaporant material is desired to be evaporated by the electron gun within electron chamber 55, yoke assembly 31 together with filament assembly 43 are pivoted upwardly by positioning lever assembly 5. This frees electron chamber 55 from evaporant material 113 or any undesired evaporant material which may pass underneath it. While the yoke 31 and filament assembly 43 are in the raised condition, a new evaporant material may be placed for evaporation. If the desired evaporant material is located on a turret translationally removed from filament assembly 43, for example turret 93, then handle 27 is moved in a clockwise direction against the urging of spring 23 to free rib 22 of lug 21 from one of the circumferential slots 12. Barrel 9 is then pulled outward and handle 27 released allowing rib 22 to find the next adjacent slot. The translational position of turret 93 with respect to filament assembly 43 is then correct. Radial positioning is adjusted by simply rotating the barrel 9 in either a clockwise or a counterclockwise direction which frees detent 128 from the longitudinal groove 129 in which it is disposed. When a subsequent longitudinal slot is encountered by detent 128, an evaporant material will be disposed in proper relationship to the filament assembly 43. If the radial position of the desired evaporant is more than one place removed, then as many of the longitudinal slots 129 as are required are bypassed.

Simultaneous evaporation or sublimation of evaporant materials contained within evaporant assembly 92 is of course possible. Because the radial and translational positions of each of the turrets are accurate, the positioning of one evaporant material with respect to one filament assembly will automatically position a corresponding evaporant material with respect to a second fiilament assembly. In short, the turrets are sized with respect to the tandemly oriented filament assemblies, such as shown in FIGURE 1, to provide the proper simultaneous disposition of evaporants within the fiilament assemblies electron chambers.

The coolant of the turrets and evaporant material contained therein is readily accomplished through the passage of coolant through bore 104, duct 105, the hollow interior of member 116, and nozzles or jets 112. The coolant will impinge upon the annular grooves 99 and 95 of turrets 93 and 100, respectively. Because of the reduced heat path provided at the base of the evaporant socket or recess, maximum cooling is accomplished. Coolant return, as has been previously described, is accomplished through coolant passages 107 and 103 disposed within plug 106, the interior of jacket 16 between distribution tube 20 and the jackets inner wall, and out through duct 133.

What is claimed is:

1. An electron gun for use in evaporating material in a vacuum chamber comprising:

(a) a body adapted to be mounted on the outside of the vacuum chamber;

(b) at least one electron source assembly carried by the body for placement within the vacuum chamber, each electron source assembly having at least one filament capable of emitting electrons upon the passage of electric current through the filament;

(c) an evaporant assembly carried by the body for placement within the vacuum chamber and adapted to mount a plurality of spaced-apart evaporant materials, the evaporant assembly being capable of cooperating with the filament of each electron source assembly to expose a selected one of the evaporant materials to such filament for evaporation; and

(d) means for selectively positioning the evaporant assembly with respect to each of the electron source assemblies to expose any selected one of the evaporant materials to the filament of such assembly.

2. The electron gun claimed in claim 1, wherein the evaporant assembly includes at least one turret, each of the turrets being adapted to mount a plurality of spacedapart evaporant materials around its radial periphery.

3. The electron gun claimed in claim 2, wherein each of the electron source assemblies includes a filament housing, each filament housing having an electron chamber capable of receiving at least a portion of a selected one of the evaporant materials, and at least a portion of the filament of each electron source assembly being disposed in its associated filament housing such that electron communication between such filament and such selected one of the evaporant materials is possible.

4. The electron gun claimed in claim 3, wherein the selective positioning means includes means for raising the filament housings with respect to the evaporant assembly such that each electron chamber may be disposed above the evaporant material.

5. The electron gun claimed in claim 4, wherein the selective positioning means includes means for rotating the turrets about their longitudinal axes.

6. The electron gun claimed in claim 5, wherein the selective positioning means includes means for translating the turrets along their longitudinal axes.

7. The electron gun claimed in claim 6, including:

(a) locking means operable to lock the turrets against rotation upon the rotational positioning of an evaporant material at least substantially coaxial with one of the electron chambers;

(b) locking means for locking the turrets against translation upon the translational positioning of an evaporant material at least substantially coaxial with one of the electron chambers; and

(c) means to release the translational and rotational locking means.

8. An electron gun for use in evaporating material in a vacuum chamber comprising:

(a) a body having a mounting collar for securing the body on the outside of the vacuum chamber;

(b) a yoke assembly pivotally mounted to the body and adapted to extend into the vacuum chamber; (c) at least one filament assembly carried by the yoke assembly, the filament assembly including an electron chamber and means for mounting at least one filament in electron communication with the electron chamber;

(d) a turret assembly carried by the body and adapted to extend into the vacuum chamber, the turret assembly having at least one turret, the turret including a plurality of means for mounting evaporant materials around its radial periphery such that a single evaporant material at a time is capable of being received in the electron chamber;

(e) means for selectively positioning the turret assembly with respect to the filament assembly to expose any desired one of evaporant materials mounted in the turret to electron bombardment; and

(f) means on the body operable from outside the vacuum chamber for raising and lowering the yoke assembly about its pivot.

9. The electron gun claimed in claim 8, wherein the body includes:

a cylindrical portion disposed normal to the mounting collar and an axial cylindrical bore extending through the cylindrical portion and the mounting collar; the turret assembly including;

a cylindrical turret support member rotatably and slidably carried by the body in its axial cylindrical bore and capable of extending into the vacuum chamber, the turret support member carrying the turrets; and

the selective positioning means cooperates with the turret support member such that the turrets are positionable through the support member in both translation and rotation.

10. The electron gun claimed in claim 9, wherein the selective positioning means include a barrel, the barrel being rotatably and slidably mounted to the body around its cylindrical portion, and the turret support member being keyed to the barrel for movement therewith.

11. The electron gun claimed in claim 10, including:

(a) rotational locking means for fixing the rotational position of an evaporant material mounted on the turret;

(b) translational locking means for fixing the transla tional position of an evaporant material mounted on the turret; and wherein (c) the rotational and translational locking means are operable by the selective positioning means.

12. The electron gun claimed in claim 11, wherein:

(a) the rotational locking means includes a plurality of longitudinally spaced-apart grooves in the cylindrical surface of the cylindrical portion of the body, each groove corresponding to the rotational position of one of the evaporant material mounting means, and a detent mounted in the barrel in locking communication with the grooves; and

(b) the translational locking means includes a lug rotatably mounted in the body, a plurality of circumferentially spaced-apart slots in the inner surface of the barrel, each slot corresponding to the translational position of one of the evaporant material mounting means, the lug being capable of engaging one of the slots at a time.

References Cited UNITED STATES PATENTS 3,303,320 2/1967 Miller l331 XR ROBERT K, SCHAEFER, Primary Examiner.

M. GINSBURG, Assistant Examiner.

Claims

1. AN ELECTRON GUN FOR USE IN EVAPORATING MATERIAL IN A VACUUM CHAMBER COMPRISING: (A) A BODY ADAPTED TO BE MOUNTED ON THE OUTSIDE OF THE VACUUM CHAMBER; (B) AT LEAST ONE ELECTRON SOURCE ASSEMBLY CARRIED BY THE BODY FOR PLACEMENT WITHIN THE VACUUM CHAMBER, EACH ELECTRON SOURCE ASSEMBLY HAVING AT LEAST ONE FILAMENT CAPABLE OF EMITTING ELECTRONS UPON THE PASSAGE OF ELECTRIC CURRENT THROUGH THE FILAMENT;