US3901183A - Wafer treatment apparatus - Google Patents

Abstract

An isolation lock for a beam treating chamber includes an evacuable lock having a top entrance closure and a bottom exit closure and adapted to receive a wafer therein. The bottom closure being operable to an inclined position in alignment with an inclined receiver whereby to gravity feed said wafer onto the receiver. The receiver includes means to retain said wafer in a fixed position thereon and is movable to dispose the fixed wafer for beam treatment within the chamber.

Description

United States Patent 11 1 1111 3,901,183 Wittkower Aug. 26, 1975 [54] WAFER TREATMENT APPARATUS 2.996.038 8/1961 Hunickc 118 50 3,084,779 4/1963 Mladck et a1 198/27 [751 mentor: Andrew Rockport 3,167,167 1 1965 Key 198 26 Mass- 3,260,383 7/1966 Fitz 06mm 214 17 B 3,560,300 2 1971 Eigenmann... 118/50 x [73] Ass'gnee Extm corporamncloucester 3,714,925 2 1973Helm 118/49 Mass.

[22] Filed: Nov. 18, 1974 Appl. N0.: 524,979

Related US. Application Data [63] Continuation-impart of Scr. No. 369,153, June 12,

1973, abandoned.

[52] US. Cl ll8/49.l; 198/26; 214/17 B [51] Int. Cl. C23C 13/08 [581 Field of Search ll8/48-49.5, 118/50, 50.1, 500-503; 198/26, 27; 34/92, 242; 214/17 A, 17 B, 17 C, 17 CA, 18 R [56] References Cited UNlTED STATES PATENTS 2,516,908 8/1950 Pottlc 118/50 Primary Exarnir'terMorris Kaplan [5 7 ABSTRACT An isolation. lock for a beam treating chamber includes an evacuable lock having a top entrance closure and a bottom exit closure and adapted to receive a wafer therein. The bottom closure being operable to an inclined position in alignment with an inclined receiver whereby to gravity feed said wafer onto the receiver. The receiver includes means to retain said wafer in a fixed position thereon and is movable to dispose the fixed wafer for beam treatment within the chamber.

31 Claims, 16 Drawing Figures PATENTEDAUGEBIQTS SHEET PATENTED AUG 2 6 I975 .SHEET PATENTED mszsms SHEET FIG 5B FIG 5A FIG PATENTED m 3,901 183SHEET 7 10 I76 I76 I54 I54 I FIG 9 FIG ilo PATENTEDAUGZBIQYS Y 3,901,183

SHEET 1o 10 FIG l5 WAFER TREATMENT APPARATUS CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my previous patent application Ser. No. 369,153, filed June 12, 1973, now abandoned for Wafer Treatment Apparatus.

BACKGROUND OF THE INVENTION This invention relates to apparatus for treating discrete items in a protected environment with one or more treatment beams and, in important aspects, to apparatus for the implantation of ions in a semiconductor wafer, the implantation occurring in a vacuum. (As used herein beam" refers to a flow of neutral or charged particles (e.g., electrons, molecules, molecule clusters, etc.) or electromagnetic quanta whether or not collimated or even exhibiting mean flow direction. Thus, a beam will be understood to include sputtering, vacuum depositing, and other techniques as well as more highly directional conventional beams.)

A number of competing goals are typically encountered in the design of such apparatus. Thus, while it is desirable to keep the apparatus simple and reliable in construction, it is also desirable to have it precise in operation so as not to damage fragile and expensive semiconductor wafers and also to minimize the labor requirements in feeding wafers to the apparatus and withdrawing treated wafers therefrom. This latter goal is important, of course, to reduce the cost of treating such wafers, but also to minimize the likelihood of contami nation of the pre-cleaned wafers by contact with a human being.

Furthermore, in the treatment of various items in a vacuum, and particularly in the implantation of ions in a semiconductor wafer, it is highly desirable that the items assume a particular orientation with respect to other elements of the apparatus during the actual treat ment of the item.

SUMMARY OF THE INVENTION In view of the foregoing, it is a principal object of the present invention to provide apparatus for the processing of discrete items in a protected environment which requires a minimum of human labor, can process the items in a rapid and precise manner, can accept items on a continuous basis (e.g., such as items fed from a conveyor), and can precisely orient the items with re spect to other portions of the apparatus.

According to the invention apparatus for processing discrete wafer-form items in a protected environment comprises a chamber and an isolation lock through which the item moves in a path between outside and inside the chamber. The isolation lock includes a casing and a bottom closure member across the path, the member defining an item-receiving surface for items when the member is in a closed position. The member is movable downwardly to an open position where the item'receiving surface resides at an angle to the horizontal to define a slide surface for sliding, guided grav-' ity movement of an item from the lock to a receiver. The apparatus also includes means for producing a treatment beam in the chamber. The receiver is movable to a position which exposes a waferform item retained thereon to the beam. Preferably, the chamber is a vacuum chamber, and means are provided for evacu ating the lock; the lock is at the entry of the chamber, the receiver comprising a wafer holder within the chamber, the member being movable into the interior of said chamber to a position aligned with the wafer holder therebelow, adapted to slidably guide waferform items into the wafer holder; the wafer holder comprises a member rotatable from a wafer receiving position to an exposure position and also from the exposure position to a'downwardly sloping discharging position in which it defines a slide surface for guided gravity movement of an item; an exit lock is provided (the bottom closure member being constructed as the firstmentioned closure) which is adapted to receive items from the wafer holder, and, upon opening, to discharge the items to a receiver outside the chamber; and each bottom closure member comprises either a swingable door or a slidable movable piston.

In another aspect of the invention such apparatus may be combined with a pair of conveyors to achieve a fully automated wafer treatment system. One conveyor is arranged to deliver wafer-form items to the bottom closure member of the entry lock, and the other arranged to convey away wafer-form items received from the bottom closure member of the exit lock.

The invention also features, in such apparatus a wafer holder which includes means for rotating a wafer-form item in its own plane to orient said items relative to an exposure position. For use with round waferform items having a predetermined flat edge at one point on the periphery, the items designed to be oriented in the wafer holder relative to that flat, the wafer holder comprises three support points arranged to supportingly receive the round periphery of the items, the middle of the points defined by a rotary drive element adapted to so apply rotative force to the edge of the items until arrival thereat of the flat,

The invention also features improvements in apparatus for processing discrete wafer-form items in a protected environment, the apparatus including a vacuum chamber, means for producing a treatment beam in the chamber, positioning means for disposing an item for exposure to the beam, delivery means for delivering the item to the positioning means, and receiver means for receiving the item from the positioning means after the exposure. According to the present invention, the positioning means comprise a wafer holder having structure defining the plane of the item disposed thereon, and means for swinging the holder to predetermined orientations with respect to a substantially horizontal axis, the axis being-positioned below the delivery means and above the receiver means. That plane, in a first holder orientation, is upwardly sloped with respect to that horizontal axis and is disposed to receive the item by sliding guided gravity movement from the delivery means, that plane, in a second holder orientation, is downwardly sloped with respect to that horizontal axis and is disposed to deliver the item to the receiver means by a sliding guided gravity movement.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features, and advantages of the invention will appear from the following description of-particular preferred embodiments, taken together with the accompanying drawings. In the drawings:

FIG. I is a somewhat schematic diagram illustrating the operation of apparatus constructed according to the present invention;

FIG. 2 is a partially broken away side elevation of a preferred embodiment of apparatus constructed according to the invention;

FIG. 3 is a plan view of the apparatus of FIG. 2;

FIG. 4 is an end view of the apparatus of FIG. 2;

FIGS. 5A and 5B and FIG. 6 are views of alternative wafer holders constructed according to the present invention for use in the apparatus of FIGS. 1 or 2;

FIG. 7 is a partially broken away side elevation of another embodiment of apparatus constructed according to the present invention;

FIG. 8 is a sectional view of the entrance lock of the apparatus of FIG. 7; I

FIGS. 9 and 10 illustrate two steps in the operation of the lock of FIG. 8; I

FIGS. 11, 12, and 13 are schematic diagrams illustrating alternative apparatus arrangements, according to the present invention, which provide for multiple treatments of wafers within a single vacuum chamber;

FIG. 14 is a schematic drawing illustrating an embodiment which provides for preand post-treatment conditioning within the vacuum chamber of the apparatus; and

FIG. 15' is a fragmentary perspective view of a portionof the apparatus of FIG. 2 or FIG. 7.

DETAILED DESCRIPTION OF PARTICULAR PREFERRED EMBODIMENTS FIG. 1 is a greatly simplified, somewhat schematic illustration of a system constructed according to the present invention for implanting ions in semiconductor wafers in a vacuum. In FIG. 1 the ion beam is represented by acone 10 emanating from an ion source and scanner l2 and terminating in the target plane which may be taken as theopen end 14 of evacuated tube 16 (i.e., the Faraday cage) within which the ion source and beam are disposed. The apparatus includes anupper vacuum lock 18 for achieving entry of thewafers 20 into the vacuum chamber and alower vacuum lock 22 for removing the implanted wafers from the vacuum chamber. The upper vacuum lock includes upper and lower closure members in the form ofdoors 24, 26 each mounted for swinging motion adjacent the opening 28 into the vacuum chamber itself. Each door is movable between a first position in which it makes a substantially air-tight seal around the opening 28 and a second position in which one end of the door is swung away from the opening 28.

Thewafers 20 are delivered to thevacuum lock 18 on a conveyor which approaches the vacuum lock from the direction toward which thedoor 24 opens.

With thedoor 26 closed and thedoor 24 opened, a wafer riding on theconveyor 30 will slide into theopening 28 and rest on the upper surface ofdoor 26. At that point sequencing andcontrol unit 43 causesdoor 24 to close and the space 28 (the space betweendoors 24 and 26 in their closed positions) to be connected to a roughing vacuum pump (not shown). The pump evacuates this space, preferably to a vacuum of approximately 10 microns. At that time, thelower door 26 is caused to swing to asecond position (i.e., the open position shown in FIG. 1) so that the wafer can slide under the influence of gravity onto wafer holder orreceiver 32 which is aligned at that time to have a receiving surface disposed in the plane of the surface ondoor 26 that the wafer is resting upon. Means are provided to maintain thewafer 20 on theunit 32 during its subsequent motion (as further described below). Theholder 32 is then caused to rotate substantially a vertical orientation closing off the end oftube 16 whiledoor 26 closes once again. At that time the ion beam is activated to accomplish the implantation of ions in thewafer 20. Valving (not shown) connects thespace 28 to the ambient to permitupper door 24 to open so that the vacuum lock is ready to receive the next wafer.

On completion of this implantation,unit 32 is caused to swing to a third position which is indicated at 34 in FIG. 1. In this position the surface supporting thewafer 20 is again angled with respect to the vertical and aligned so that the wafer can slide into theremoval opening 36 which is exposed by the openupper door 38 of thelower vacuum lock 22. After the wafer has been deposited in theopening 36, theupper door 38 closes and a valve (not shown) is caused to operate connecting the base 36 with the ambient to relieve the vacuum therein. Then thelower door 40 swings open to an appropriate angle such that thewafer 22 may slide on the upper surface of that door to be ultimately deposited on aremoval conveyor 42.Door 40 then closes and the space betweendoors 38 and 40 is reevacuated to about 10 microns. The sequencing andcontrol unit 43 controls the movements of the doors and the wafer holder as well as the operation of the valves which evacuate and pressurize the vacuum locks.

A preferred embodiment is shown in more detail in FIGS. 2-4. Thetube 16 through which the ion beam travels (as indicated byarrow 44 in FIG. 2) communicates with avacuum chamber 46 defined by acasing 48. Theupper vacuum lock 18 in the upper casing wall comprises opening 50 in the wall, afirst door 52 exterior of thechamber 46 and asecond door 54 interior of thechamber 46. Each door overlaps thecasing 48 so as to, in its closed position, form a substantially airtight, face-to-face seal with the casing. Theupper door 52 is connected to arotatable shaft 56 byribs 58 which are secured to both the door and the shaft. Theshaft 56 is supported for rotation insupports 60 which in turn are secured to the upper surface ofcasing 48. Arod 62 is secured to theshaft 56 in the center thereof and forms a part of a linkage which causes movement of thedoor 52, in a rotational fashion, between open and closed positions. As shown in FIG. 4,rod 62 is pivotally secured to the piston 51 of a vertically mountedpneumatic cylinder 53. Vertical motion of piston 51 thus causes the desired rotation ofrod 62 andshaft 56.

Thelower door 54 ofupper vacuum lock 18 includes an upper planar wafer-receivingsurface 64. Thedoor 54 is supported byribs 66 for movement about anaxis 68 between a first or closed position as shown in FIG. 2 and an open, angled position which is indicated in a broken line representation in FIG. 2. This motion is effected by motion of arod 70 which moves a portion of pneumatic valve actuator (the remainder not shown) and which enters thechamber 46 through one end 72 thereof. (The structure which accomplishes this, and its operation, is identical to that which moves the upper, interior door of theexit vacuum lock 22, all as described below. To simplify the drawing, this structure has been omitted ondoor 54.)

A wafer receiver orholder 74 is disposed within thechamber 46 and is mounted for rotation on ashaft 76. Thedevice 74 is in the general form of a receiving tray for accepting a wafer which slides under the influence of gravity fromsurface 64 ofdoor 54. Aplanar surface 78 is the actual surface which receives the wafer. Thedevice 74 is rotatable about the axis ofshaft 76 so as to be positionable in at least three separate positions. The first position is indicated by reference line X (see FIG. 2), the second position by reference line Y, and the third position by reference line Z. In the first position thesurface 78 is substantially aligned withsurface 64 of thedoor 54 when the door is open. In the second position thesurface 78 is generally upright and dis posed in the open end oftube 16 within thechamber 46. (As shown in FIG. 2, however, it is often desirable that in this position the wafer be not precisely upright but angled with respect to the vertical at an angle of about 7. As is well known in the art, such angling is often desirable to prevent a phenomenon as channeling which can occur during the implantation of ions in a crystalline lattice.) In the third position, indicated by reference line Z, thesurface 78 is angled with respect to the vertical such that a wafer supported onsurface 78 can slide under the influence of gravity to be received upon theupper surface 80 of alower door 82 which forms a part of the lower, or wafer-removal,vacuum lock 22. As with the upper vacuum lock, thatdoor 82 overlaps thecasing 48 around an opening 84 in the casing to form a face-to-face seal with the casing.Ribs 86 connect thedoor 82 with arotatable shaft 88. Arod 90 secured to shaft 88 (see FIG. 4) forms part of a linkage'for a conventional mechanism for rotating theshaft 88 to cause motion of thedoor 82 between its closed position as illustrated in FIG. 2 and an open position in which thesurface 80 is angled with respect to the vertical, as shown by the broken line representation in FIG. 2.

Thelower vacuum lock 22 also includes anupper door 92 which overlaps thecasing 48 around the open ing 84 to effect a substantially air-tight, face-to-face seal in the closed position of the door, illustrated in FIG. 2.Ribs 94 are secured to bothdoor 94 and ashaft 96 supported for rotation insupports 98 within thechamber 46. Structure 100 projects upwardly from thedoor 92 and includes anoblong opening 102 which in the closed position of the door is angled with respect to the horizontal. Aroller 104 is disposed in theopening 102 and is linked by arod 106 to arod 108 which forms a portion of a pneumatic valve actuator (the rest of which is not shown) of conventional design. The motion ofrods 106, 108, androller 104 to the right as viewed in FIG. 2 causes the upward swinging ofdoor 92 from its closed position to the open position shown in broken line form in FIG. 2.

In the open position ofdoor 82 thesurface 80 is generally aligned with'the upper end of aguide chute 108 which conducts a wafer from thesurface 80 to aconveyor 110 aligned with the lower end ofchute 108.

Thecasing 48 also includes anopening 112 which receives aconduit 114 that is ultimately connected to a vacuum pump (not shown). Anopening 116 is provided in the upper surface ofcasing 48 and is aligned with reference line Y (i.e., the position of the Wafer to be treated in its treatment orientation).Glass viewing disc 115 overlies theopening 116 and is supported in a threadedretainer 120 forming an air-tight seal withresilient seal member 119 which is disposed in a groove which surrounds theopening 116.

The movement of theunit 74 between positions X, Y, and Z is produced by means of agear 118 which is secured to theshaft 76 exterior of thechamber 46. This is indicated schematically in FIG. 2 and more representationally in FIG. 3. Arack gear 121 engages the gear 1 18 and is itself attached to arod 122 which is attached to apiston 124 in apneumatic cylinder 126. Air supply and sequencing control (not shown) of conventional design are provided for thecylinder unit 126.

Simple mechanical stops, of course, are sufficient to achieve precisely the desired locations for theunit 74 in the second and third positions (i.e., the positions identified by reference lines Y and Z For the first position (indicated by reference line X), however, a oneway stop is required. Thus, as theunit 74 is swinging from the second position (reference line Y) to the third position (reference line Z) to discharge an implanted wafer, the position at reference line X must simply be by-passed. After the wafer has been deposited in the removal opening 84 (andupper door 92 has closed to preserve the vacuum within the chamber 46), theunit 74 begins its counterclockwise motion and must stop at its first position (reference line X) to receive the next wafer fromsurface 64 ofdoor 54. To this end aoneway stop 128, indicated schematically in FIG. 2, is provided adjacent the reference line X. This stop may be at a conventional design; e.g., being spring loaded with a camming surface which forces the stop to retract as theunit 74 passes in a clockwise direction and a stop surface which engages theunit 74 as it approaches in a counterclockwise direction. Conventional sequencing and control apparatus can be employed to move the stop member against the force of the biasing spring after the fresh semiconductor wafer has been deposited onsurface 78 so that theunit 74 may then swing to its second position (reference line Y).

Two particularly preferred forms of the wafer receiver orholder 74 are illustrated in FIGS. 5A and 5B, and 6. Referring to FIGS. 5A and 5B, theholder 74 comprises a planarrigid member 123 for receiving awafer 20. A pair of V support stops 127 are disposed on the upper surface ofmember 123 adjacent thewafer 20 and spaced from each other approximately around the periphery of thewafer 20. The wafers periphery is thus held by the relieved area beneath the support stops 127.

In FIG. 6, theunit 74 is generally in the form of a tray including asurface 78 for receiving awafer 20 and anupstanding lip 130 disposed around three sides of thesurface 78. Threeretainer members 134, 136, 138 are raised above thesurface 78 approximately the thickness of thewafer 20 and are located to partially overlie the peripheral portions of awafer 20 which is properly located on thesurface 7 8. Each of themembers 134, 136 is rigidly secured to thesurface 78 and is undercut (as indicated at 140, 142) to receive thewafer 20. Themember 138 is a disc mounted for rotation about anaxis 144 and is located such that the periphery of thedisc 138 engages the periphery of thewafer 20.

It will be apparent to those skilled in the art that the operation of the unit as shown in FIG. 5B is such that awafer 20 may be supported in a plane (i.e., the plane of surface 78), that plane rotated to a predetermined orientation (as by rotation of theunit 74 aboutshaft 76 between reference lines X and Y of FIG. 2), and thewafer 20 itself may be rotated in that plane to achieve a preferred orientation of the crystalline lattice of the wafer. This latter rotation is achieved by thedisc 138 which, as it rotates, causes a rotation of thewafer 20. Such rotation ofdie wafer 20 continues until a flat 146 (such as is often conventionally provided on the periphery of a otherwise circular wafer) reaches a rotational orientation of wafer there is no longer physical contact between thedisc 138 and the wafer and rotation of the wafer ceases. Thus, by rotation of theunit 74 about theaxis 76 to a preferred orientation (e.g., the 7 orientation with respect to the ion beam shown in FIG. 2) and the rotation of thewafer 20 in the plane ofsurface 78, preferred orientations of two axes of the crystalline lattice with respect to the ion beam can be achieved.

FIG. 7 is a view similar to FIG. 2 of another embodiment of an ion implantation system constructed in accordance with the present invention. The present description will concern the entrance and exitisolation locks 148, 150 since the remainder of the apparatus is substantially identical to that of FIG. 2 and thus has already been described. As shown in FIG. 7, awaferform item 20 is delivered by conveyor to asloped guide 152 aligned with anentrance aperture 154 of theentry isolation lock 148. The lock as a whole is tilted, and oriented with respect to guide 152, such that theitem 20 will slide under the influence of gravity through theslot 154 and into the interior oflock 148. Anoutlet slot 156 of thelock 148 is aligned with anopening 158 in thecasing 48 which defines thevacuum chamber 46. Thisopening 158 is aligned with the wafer receiver orholder 74 when that holder is in the position indicated at X in FIG. 7.

Theexit isolation lock 150 includes anentrance slot 160 aligned with opening 162 in thecasing 48, the latter positioned to be aligned with thewafer holder 74 when it resides in the wafer discharge position Z shown in FIG. 7. Anoutlet slot 164 of theexit isolation lock 150 is aligned with guide orchute 108 which transfersitems 20 from thelock 150 to aconveyor 110.

FIG. 8 illustrates the internal construction of thelock 148. (The construction oflock 150 would be substantially a mirror-image of thelock 148, as will be apparent to those skilled in the art.) 1

As will be seen from FIG. 8, thelock 148 comprise upper andlower pistons 166, 168 mounted within a generallyhollow casing 170. Each piston includes anintegral pressure plate 172, 174 and ahead 176, 178. Thecasing 170 is formed from a plurality of coaxial parts so as to facilitate manufacture and assembly and providesinternal cavities 180, 182 within whichpressure plates 172, 174, respectively, are disposed and alarger cavity 184 within which the piston heads 176, I78 are disposed. Anannular flange 186 on casingmember 188adjacent cavity 184 provides stop surfaces defining limits of travel of the pistons and, by means ofannular sealing members 190, 192, provides for an air tight seal when therespective piston head 176, 178 abuts theflange 186. Theupper surface 194 of thelower piston 158 forms a movable item-receiving surface. (It should be recalled that theentire lock 148 of FIG. 8 is supported on thecasing 48 of the apparatus in a tilted orientation such that thesurface 194 will be sloped with respect to the horizontal.) To separate high vacuum, high pressure, and intermediate pressure portions of thevacuum lock 148, circumferential resilient sealingmembers 195 are disposed around the periphery of the pressure plate and the piston shaft, both above and below the pressure plate, for each of thepistons 166, 168.Air channels 196, 196a are provided incasing members 198, 198a and communicate with thecavity 180 above and below, respectively, thepressure plate 172. Similarly,air passages 200, 200a are provided incasing members 202, 202a and communicate withcavity 182 below and above respectively, thepressure plate 174. Each of thepassages 196, 196a, 200, 200a communicates with anexterior conduit member 204 which in turn is connected to an air pressure supply andcontrol unit 206.

Anair passage 208 is also provided incasing member 188 and communicates with the volume ofcavity 184 disposed between the piston heads 176, 178. Thepassage 208 is connected, viaconduit member 210, to avacuum pump 212. An air tight bellows 214 is disposed around the central shaft ofpiston 168 and is secured at its opposite ends, in an air tight seal, to thepiston head 174 and to aflange portion 216 of the casing member 202a. A pair ofresilient bumpers 218, 220 are provided adjacent the item-receivingsurface 194 at theinput slot 154 andoutput slot 156 sides of the lock respectively. Themember 218 is secured to thepiston head 178 and has a portion 222 aligned withsurface 192 and aportion 224, radially outward therefrom, which projects upwardly fromsurface 194. Themember 220 is secured to theflange portion 186 of thecasing member 188. The individual elements forming thecasing 170 of thevacuum lock 148 can be secured together in any conventional fashion.

The operation of thevacuum lock 148 may be described with reference to FIGS. 8-10. The air supply andcontrol unit 206 is conventionally constructed to deliver high pressure to therespective air passages 196, 196a, 200, 200a in accordance with a predetermined sequence to operate thepistons 166, 168 in the manner to be described. Since the sequence is continuous and repetitive, the following description will assume an initial starting point for the sequence as shown in FIG. 9.

With high pressure air supplied topassages 196a and 200 both pistons will be in their uppermost position and thus theentrance slot 154 will not be blocked by thepiston head 176 and the high vacuum in the chamber 46 (which communicates with the exit slot 156) will be protected by the compressional seal effected by the pisto'nhead 178 bearing against theresilient seal member 192. In this configuration of the pistons, a wafer-form item 20 is gravitationally delivered to entrance slot 154 I and it slides into thelock 148 to rest upon theitemreceiving surface 194 oflower piston 168. Theresilient member 218 forms a smooth and non-abrasive surface over which theitem 20 slides to reach its position of rest onthesurface 194 and themember 220 provides a resilient and non-abrasive stop surface which theitem 20 will bear against.

With theitem 20 disposed on thesurface 194, theunit 206 disconnects the high pressure from thepassage 196a and connects it to thepassage 196, thus forcing thepiston 166 downwardly such that seal engages theflange 186. In this orientation of the pistons, the volume within which theitem 20 is disposed (the volume ofcavity 184 between the piston heads 176, 178) is isolated by the action ofseal members 190, 192 and thus becomes evacuated by the action of the continuously operatingvacuum pump 212. After this evacuation, theunit 206 interrupts the high pressure connected topassage 200 and connects high pressure to the passage 2000 thereby forcing apiston 168 to its lower position, as is illustrated in FIG. 10. In this position, thesurface 194 ofpiston 168 will be positioned relative to theexit slot 156 such as to permit guided sliding motion under the influence of gravity of theitem 20 from thesurface 194 through theexit slot 156 and on to thesurface 78 of holder 74 (see FIG. 7). After theitem 20 has left thelock 148, theunit 206 switches the high pressure air from passage 200a back to thepassage 200 thereby achieving the piston orientation shown in FIG. 8. Theunit 206 then transfers the high pressure fromair passage 196 toair passage 196a and drives theupper piston 166 to its upper position illustrated in FIG. 9 for a resumption of the cycle just described.

The portion ofcavity 184 belowpiston head 178 will be at high vacuum conditions at all times during the operation cycle of thelock 148. The portion ofcavity 182 above thepressure plate 174, on the other hand, will sequentially experience high pressure conditions. With this arrangement, it would be difficult to maintain the required isolation of high pressure from high vacuum solely by means of slidingseal 195 around the shaft ofpiston 168 abovepressure plate 174. The addition ofbellows 214, therefore, provides the required isolation of the high pressure from the high vacuum.

FIGS. 1l14 illustrate embodiments in which waferform items may receive plural treatments within a vacuum chamber. In FIG. 11, which corresponds substan tially to the view of FIG. 1, there are a pair of horizontally alignedtubes 16, 16a for delivering beams generated frombeam sources 12, 12a to the target plane of the open ends 14, 14a of the tubes. The entrance and exit vacuum locks 18 and 22 operate as previously described, as do the wafer holders orreceivers 32, 32a. In the embodiment of FIG. 11, however, aconveyor 218 is disposed to receive on its upper length a wafer discharged from theholder 32 when in its downwardly sloping wafer discharge position Z. The direction of travel of theitem 20 on the conveyor is both horizontal in the direction of the second tube 16a and upward as indicated by slopingportion 220 of theconveyor 218. The discharge end 222 of the conveyor is positioned at substantially the same elevation as theentrance lock 18 and at a lateral position adjacent the second tube 16a and wafer holder 320. Awafer guide structure 224 which includes a wafer support surface 226 is disposed adjacent the discharge end 222 of the conveyor and receives items discharged from the conveyor. Theunit 224 changes the orientation of travel of an item by 90 in the horizontal plane and lowers the leading edge thereof for guided sliding gravitational movement onto the wafer holder 320 when positioned in its wafer receiving position X. It is thus apparent that theholders 32, 32a serve as wafers supports which receive wafers, move them to a treatment position (adjacent theopen end 14, 14a of the tube), and then move them to a discharge position. The wafers are discharged fromsupport 32 to conveyor 21 8 and from support 320 to theexit lock 22.

FIGS. 12 and 13 are schematic illustrations of multiple-treatment machines in which the treatment beams are vertically rather than horizontally aligned. Each of these embodiments, once again, for simplicity includes only two different treatment beams. In each embodiment there are a pair ofreceivers 32, 32a which function substantially as described above with reference to both FIGS. 1 and 11. In the embodiment of FIG. 12, by

providingbeams 44, 44a which travel to the treatment region from opposite directions, the second wafer support 32a actually becomes the receiver which receives an item directly from thesupport 32 when thesupport 32 is in the item discharge position Z. In the embodiment of FIG. 13, arotary receiver 228 is provided for step-wise motion about anaxis 230 and includes a plurality of integralitem receiving portions 232. With each step in the motion of thereceiver 228, one of themembers 232 will be aligned for receiving an item from thefirst support member 32 and asecond member 232 will be disposed for delivering an item previously deposited thereon to the second support member 32a. In each of the embodiments of FIGS. 12 and 13 the appropriate item-receiving surface of theexit lock 22 forms the receiver downstream of a second support member 32a.

In the embodiment of FIG. 14, the entrance and exit locks 18, 22 are laterally displaced from thesupport 32 and the target plane of thebeam 44. Upper andlower conveyors 234, 236 are provided and each has its upper length extending between therespective lock 18, 22 and thesupport 32. Theupper length 238 of theupper conveyor 234 is heated by means ofheating elements 240 and theupper length 242 oflower conveyor 236 is cooled by means of coolingelements 244. With this arrangement, an item may be pre-conditioned and post-conditioned within the vacuum chamber prior to and subsequent to, respectively, receiving treatment by thebeam 44. In the embodiment illustrated, the pretreatment heating provides for annealing of the wafers crystalline lattice during the ion bombardment and the cooling of the treated wafer prior to its return to room temperature. The provision of theconveyors 232, 236, or equivalent means, intermediate thelocks 18, 22 and thesupport 32 permit a relatively slow and uniform heating and cooling of the items without severely limiting the rate at which items are treated by the beam 44 (since many items may simultaneously be positioned at various locations along each conveyor at any given instant).

FIG. 15 illustrates one preferred embodiment of a mechanism for achieving the step-wise swinging motion of the wafer-holder 74 between the three positions illustrated in FIGS. 2 and 7. In FIG. 15, thewafer holder 74 is shown very schematically and is rigidly secured to ashaft 246 which passes through thecasing 48 in a conventional air-tightrotational seal 248. Exterior of the vacuum chamber theshaft 246 is secured for rotation with amember 250 which has a pair ofintegral posts 252 projecting radially therefrom and which includes stop surfaces 254 adjacent thepost 252 at a predetermined distance from the axis ofshaft 246.Slide members 256 each have an opening therethrough for receiving one of therods 252.Springs 258 are disposed around the rods between theslide members 256 and an upperrigid support 260. Arod 262 disposed parallel to theshaft 246 links theslide members 256.

A pair of parallel linkingarms 264 are pivotally secured to therod 262 at one end and pivotally secured to adrive arm 266 at the other end. Thedrive arm 266 extends from thelink arms 264 to adrive shaft 268 to which it is secured for rotation. Thedrive shaft 268 is parallel to theshaft 246 and is in turn secured for rotation with ageneva wheel 270 of conventional construction. Adrive wheel 272 is mounted adjacent thegeneva wheel 270 and is driven by amotor 274. Acurved cam surface 276 secured to thedrive wheel 272 is disposed to engage mating curve surfaces 278 of the geneva wheel.Drive pin 280 also secured to drivewheel 272 is disposed to engage, at the appropriate point in the rotation of thedrive wheel 272,slots 282 of thegeneva wheel 270. A counter-switch 284 is disposed to be activated by thepin 280 once during each revolution of thedrive wheel 272 and is connected in a conventional fashion (not shown) to reverse the direction of rotation of themotor 274 after a predetermined count has been achieved.

Acam member 286 having anupper cam surface 288 is supported to engage the under surfaces oflink arms 264 adjacent their pivotal connection withrod 262. The distance of thecam surface 288 from the axis ofshaft 246 is adjustable by means of adjustments through 290 which is supported in astructural member 292 of the apparatus.

In the operation of the mechanism illustrated in FIG. 15 we may consider as a starting orientation that orientation in which theholder 74 is in the wafer discharge position indicated at Z. Themotor 274 is then actuated to drive thedrive wheel 272 in a counterclockwise sense as viewed in FIG. 15. The engagement ofarcuate cam surface 276 with amating surface 278 of thegeneva wheel 270 maintains the geneva wheel, and thus the remainder of the mechanism, in a fixed rotational orientation for a period of time determined by the portion of a full circle over which thearcuate surface 276 extends and the rate at which thewheel 272 is driven. As thesurface 276 is about to disengage theparticular surface 278 on thegeneva wheel 270, therod 280 engages thenext slot 282 of the geneva wheel and, with the continued rotation of the drive wheel, produces an incremental clockwise rotation of thegeneva wheel 270 such that the nextarcuate surface 278 thereof will be positioned for engagement with thesurface 276 on the drive wheel. This rotation is transmitted byrod 268 to thedrive arm 266. Thelink arms 264 transmit this same rotation to themember 250 and, thus, ultimately to theshaft 246 and thewafer holder 74. Thewafer holder 74 will then be in the position X for receiving a fresh wafer. In one preferred embodiment the step-wise displacement of thegeneva wheel 270, and thus the angular displacement of thewafer holder 274 between the positions Z and X, is 72. In this same preferred embodiment, however, the angular displacement of the wafer holder between the positions X and Y is of the order of 50. In order to retain the mechanical simplicity of asymmetrical geneva wheel 270, thecam member 286 has been provided to converge the next incremental 72 rotation of thegeneva wheel 270 into a lesser portion of thewafer holder 74. Thus, thesurface 288 is positioned such that during the next rotation of the geneva wheel the under surfaces oflink arms 264 will bearagainst thecam surface 288 and will be forced upward thus movingslides 256 upwardly on therods 252 against the force of biasing springs 258. This will effectively increase the length of the arm which is parallel to thearm 266 in the parallelogram linkage illustrated. This arm consists of themember 250 and the portions of therods 252 below the location of the cross-rod 262. The upward motion of therod 262 produced by thecam surface 288, therefore, lenghthens this arm of the linkage during the second incremental motion of the geneva wheel and thereby reduces the magnitude of the rotation produced in theshaft 246 and theholder 74. Theadjustment screw 290 permits the small changes in the placement of thecam surface 288 and thus provides for a range of angles between the holder orientations at positions X and Y by this very easy adjustment. In one preferred embodiment, this range is from 44 to 54 with the 54 value orienting theholder 74 in a substantially vertical orientation. With this arrangement other angles chosen in the range of 44 through 54 will result in a slightly off vertical implantation position Y of theholder 74 such as illustrated in FIGS. 2 and 7.

The preferred vacuum lock construction as illustrated in FIGS. 8-10 is the joint invention of myself and Geoffrey Ryding.

While particular preferred embodiments of the present invention have been described in detail and illustrated in the accompanying drawings, other embodiments are within the scope of the invention and the following claims.

I claim:

1. Apparatus for processing discrete wafer-form items in a protected environment, including a vacuum chamber and an isolation entry lock through which a said item moves in a path between outside and inside the chamber, said isolation lock including a casing and a bottom closure member across said path, said bottom closure member overlapping a peripheral portion of said casing forming a face-to-face seal therewith, said member defining an item-receiving surface for said item when said member is in a closed position, said member being movable downwardly to an open position where said surface resides at an angle to the horizontal, said member in said open position defining a slide surface for sliding, guided gravity movement of said item from said lock to a receiver, means for producing a treatment beam in said chamber, said receiver including means to retain said wafer form thereon and said receiver being movable to a position exposing said retained wafer-form item to said treatment beam.

2. The apparatus of claim 1 wherein said apparatus is ,an ion implantation device, said treatment beam comprising ions.

3. The apparatus of claim 1 wherein said receiver comprises a wafer holder within said chamber, said bottom closure member in said open position being aligned with said wafer holder therebelow, adapted to slidably guide said waferform item into said wafer holder.

4. The apparatus ofclaim 3 wherein said wafer holder comprises a rotatable member, rotatable from a wafer receiving position to said exposure position.

5. The apparatus ofclaim 4 wherein said wafer holder is rotatable from said exposure position to a downwardly sloping discharging position, said holder in said downwardly sloping position defining a slide surface for guided gravity movement of said item from said holder.

6. The apparatus ofclaim 5 including an exit lock, the bottom closure of said exit lock being constructed also in accordance with claim 1, adapted to receive a said item from said wafer holder, and upon opening, to slidably discharge said item to a receiver outside said chamber.

7. The apparatus ofclaim 6 including a pair of conveyors, one arranged to deliver wafer-form items to said bottom closure member of said entry lock, and the other arranged to convey away wafer-form' items re- 1 ceived from said bottom closure member of said exit lock.g I h 8. The apparatus ofclaim 4 wherein said wafer holder includes means for rotating a said .wafer'j-f drml item in itsown plane to orient said item relative to saidexposure position. 1 v

9. The apparatus of Claim form items each having a flat edge at one predeter-' mined point on its periphery, said items designed to be oriented in said wafer holder relative to said flat edge, said wafer holder comprising three support points arranged to supportingly receive the round periphery of said items, the middle of said points defined by a rotary drive element adapted to so apply rotative force to the round periphery of said items until arrival thereat of said flat.

10. The apparatus ofclaim 3 wherein in said waferreceiving position said wafer holder extends upwardly, at an angle to the vertical for slidably receiving a said item, said wafer holder being rotatable toward the vertical from said receiving position to said exposure position.

11. The apparatus of claim wherein said wafer holder includes a support surface and a pair of V support stops into which said wafer-form items slide into a retained position.

12. The apparatus of claim 11 wherein said wafer holder rotates from its exposure position through said receiving position to a downwardly sloping slidable discharge position at which said wafer-form item slides along said support surface of said wafer holder, out of said V support stops.

13. The apparatus of claim 1 including a movable conveyor arranged to discharge said wafer-form items upon said item receiving surface of said bottom closure member.

14. The apparatus of claim 1 wherein said lock includes a top closure member having an open position enabling entry of said wafer-form item and a closed position overlapping a peripheral portion of said casing forming a face-to-face seal therewith.

15. The apparatus ofclaim 14 wherein both said top and bottom closure members comprise swingable doors.

16. The apparatus of claim I wherein said bottom closure member comprises a swingable door.

17. Apparatus for processing discrete wafer-form items in a protected environment, including a vacuum chamber, means for producing a treatment beam in said chamber, a waferform item support within said chamber, said support being movable to a position to expose a said wafer-form item to said treatment beam, and an isolation exit lock through which the item moves from said receiver in a path between inside and outside the chamber, said isolation lock including a casing and a bottom closure member across said path said bottom closure member overlapping a peripheral portion of said casing forming a face-to-face seal therewith, said member defining an item-receiving surface for said item when said member is in a closed position, said member being movable downwardly to an open position where said surface resides at an angle to the horizontal, said member in said open position defining a slide surface for sliding, guided gravity movement of said item from said lock to discharge said item to a receiver outside said chamber.

8 foruse with roundvwafer- 18. The apparatus ofclaim 1,7? wherein said receiver comprises a movable conveyor-adapted to convey waf. er-form items away from saidchamber. v l9. Theapparatus of claim. 17 wherein saidbottom closure member comprises a'doorswingable about a v substantially horizontalaxisv 20. The apparatus of claim 17 wherein cludes a top-closure member'having anopen position enabling entryof said wafenform item and a closedposition overlapping a peripheral portion of said casing forming a face-to-face seal therewith.

21. The apparatus ofclaim 20 wherein both said top and bottom closure members comprise swingable doors.

22. In apparatus for processing discrete wafer-form items in a protected environment, including a vacuum chamber, means for producing a treatment beam in said chamber, positioning means for disposing a said item for exposure to said beam, delivery means for delivering said item to said positioning means, and receiver means for receiving said item from said positioning means after said exposure thereof to said beam, the improvement wherein said positioning means comprise a wafer holder having structure defining the plane of a said item disposed thereon, means for swinging said holder to predetermined orientations with respect to a substantially horizontal axis which is positioned below said delivery means and above said receiver means, said plane in a first holder orientation being upwardly sloped with respect to said horizontal axis and disposed to receive said item by sliding guided gravity movement from said delivery means, said plane in a second holder orientation being downwardly sloped with respect to said horizontal axis and disposed to deliver said item to said receiver means by a sliding guided gravity movement.

23. The apparatus ofclaim 22 wherein said beam has a beam axis which is horizontal, said plane in a third holder orientation being within about 10 of the vertical, said item being exposed to said beam when said holder is in said third orientation.

24. The apparatus of claim 23 for use with round wafer-form items each having a flat edge at one predetermined point on its periphery, said items designed to be oriented in said wafer holder relative to said flat edge,

round periphery of said items until arrival thereat of said flat.

25. The apparatus of claim 23 wherein said delivery means comprise an isolation entry lock constructed in accordance with claim 1.

26. The apparatus of claim 23 wherein said receiver means comprise an isolation exit lock constructed in accordance with claim 17.

27. The apparatus of claim 23 wherein said delivery means comprise means for heating said items in said chamber.

28. The apparatus of claim 27 wherein said receiver means comprises means for cooling said item in said chamber.

29. The apparatus ofclaim 28 wherein said means for heating and said means for cooling comprise conveyors having itembearing surfaces which are, respectively, heated and cooled.

said; ,lock'ini 30. The apparatus of claim 23 further including means for producing a second treatment beam spaced apart from the first mentioned treatment beam and a second positioning means associated with said second treatment beam, the second positioning means holder in its first orientation forming said receiver means.

31. The apparatus of claim 23 further including means for producing a second treatment beam spaced apart from the first mentioned treatment beam and a

Claims (31)

1. Apparatus for processing discrete wafer-form items in a protected environment, including a vacuum chamber and an isolation entry lock through which a said item moves in a path between outside and inside the chamber, said isolation lock including a casing and a bottom closure member across said path, said bottom closure member overlapping a peripheral portion of said casing forming a face-to-face seal therewith, said member defining an item-receiving surface for said item when said member is in a closed position, said member being movable downwardly to an open position where said surface resides at an angle to the horizontal, said member in said open position defining a slide surface for sliding, guided gravity movement of said item from said lock to a receiver, means for producing a treatment beam in said chamber, said receiver including means to retain said wafer form thereon and said receiver being movable to a position exposing said retained wafer-form item to said treatment beam.

2. The apparatus of claim 1 wherein said apparatus is an ion implantation device, said treatment beam comprising ions.

3. The apparatus of claim 1 wherein said receiver comprises a wafer holder within said chamber, said bottom closure member in said open position being aligned with said wafer holder therebelow, adapted to slidably guide said waferform item into said wafer holder.

4. The apparatus of claim 3 wherein said wafer holder comprises a rotatable member, rotatable from a wafer receiving position to said exposure position.

5. The apparatus of claim 4 wherein said wafer holder is rotatable from said exposure position to a downwardly sloping discharging position, said holder in said downwardly sloping position defining a slide surface for guided gravity movement of said item from said holder.

6. The apparatus of claim 5 including an exit lock, the bottom closure of said exit lock being constructed also in accordance with claim 1, adapted to receive a said item from said wafer holder, and upon opening, to slidably discharge said item to a receiver outside said chamber.

7. The apparatus of claim 6 including a pair of conveyors, one arranged to deliver wafer-form items to said bottom closure member of said entry lock, and the other arranged to convey away wafer-form items received from said bottom closure member of said exit lock.

8. The apparatus of claim 4 wherein said wafer holder includes means for rotating a said wafer-form item in its own plane to orient said item relative to said exposure position.

9. The apparatus of claim 8 for use with round wafer-form items each having a flat edge at one predetermined point on its periphery, said items designed to be oriented in said wafer holder relative to said flat edge, said wafer holder comprising three support points arranged to supportingly receive the round periphery of said items, the middle of said points defined by a rotary drive element adapted to so apply rotative force to the round periphery of said items until arrival thereat of said flat.

10. The apparatus of claim 3 wherein in said waferreceiving position said wafer holder extends upwardly, at an angle to the vertical for slidably receiving a said item, said wafer holder being rotatable toward the vertical from said receiving position to said exposure position.

11. The apparaTus of claim 10 wherein said wafer holder includes a support surface and a pair of V support stops into which said wafer-form items slide into a retained position.

12. The apparatus of claim 11 wherein said wafer holder rotates from its exposure position through said receiving position to a downwardly sloping slidable discharge position at which said wafer-form item slides along said support surface of said wafer holder, out of said V support stops.

13. The apparatus of claim 1 including a movable conveyor arranged to discharge said wafer-form items upon said item receiving surface of said bottom closure member.

14. The apparatus of claim 1 wherein said lock includes a top closure member having an open position enabling entry of said wafer-form item and a closed position overlapping a peripheral portion of said casing forming a face-to-face seal therewith.

15. The apparatus of claim 14 wherein both said top and bottom closure members comprise swingable doors.

16. The apparatus of claim 1 wherein said bottom closure member comprises a swingable door.

17. Apparatus for processing discrete wafer-form items in a protected environment, including a vacuum chamber, means for producing a treatment beam in said chamber, a waferform item support within said chamber, said support being movable to a position to expose a said wafer-form item to said treatment beam, and an isolation exit lock through which the item moves from said receiver in a path between inside and outside the chamber, said isolation lock including a casing and a bottom closure member across said path said bottom closure member overlapping a peripheral portion of said casing forming a face-to-face seal therewith, said member defining an item-receiving surface for said item when said member is in a closed position, said member being movable downwardly to an open position where said surface resides at an angle to the horizontal, said member in said open position defining a slide surface for sliding, guided gravity movement of said item from said lock to discharge said item to a receiver outside said chamber.

18. The apparatus of claim 17 wherein said receiver comprises a movable conveyor adapted to convey wafer-form items away from said chamber.

19. The apparatus of claim 17 wherein said bottom closure member comprises a door swingable about a substantially horizontal axis.

20. The apparatus of claim 17 wherein said lock includes a top closure member having an open position enabling entry of said wafer-form item and a closed position overlapping a peripheral portion of said casing forming a face-to-face seal therewith.

21. The apparatus of claim 20 wherein both said top and bottom closure members comprise swingable doors.

22. In apparatus for processing discrete wafer-form items in a protected environment, including a vacuum chamber, means for producing a treatment beam in said chamber, positioning means for disposing a said item for exposure to said beam, delivery means for delivering said item to said positioning means, and receiver means for receiving said item from said positioning means after said exposure thereof to said beam, the improvement wherein said positioning means comprise a wafer holder having structure defining the plane of a said item disposed thereon, means for swinging said holder to predetermined orientations with respect to a substantially horizontal axis which is positioned below said delivery means and above said receiver means, said plane in a first holder orientation being upwardly sloped with respect to said horizontal axis and disposed to receive said item by sliding guided gravity movement from said delivery means, said plane in a second holder orientation being downwardly sloped with respect to said horizontal axis and disposed to deliver said item to said receiver means by a sliding guided gravity movement.

23. The apparatus of claim 22 wherein said beam has a beam axis which is horizontal, said plane in a third holder orientation being within about 10* of the vertical, said item being exposed to said beam when said holder is in said third orientation.

24. The apparatus of claim 23 for use with round wafer-form items each having a flat edge at one predetermined point on its periphery, said items designed to be oriented in said wafer holder relative to said flat edge, said wafer holder comprising three support points arranged to supportingly receive the round periphery of said items, the middle of said points defined by a rotary drive element adapted to so apply rotative force to the round periphery of said items until arrival thereat of said flat.

25. The apparatus of claim 23 wherein said delivery means comprise an isolation entry lock constructed in accordance with claim 1.

26. The apparatus of claim 23 wherein said receiver means comprise an isolation exit lock constructed in accordance with claim 17.

27. The apparatus of claim 23 wherein said delivery means comprise means for heating said items in said chamber.

28. The apparatus of claim 27 wherein said receiver means comprises means for cooling said item in said chamber.

29. The apparatus of claim 28 wherein said means for heating and said means for cooling comprise conveyors having itembearing surfaces which are, respectively, heated and cooled.

30. The apparatus of claim 23 further including means for producing a second treatment beam spaced apart from the first mentioned treatment beam and a second positioning means associated with said second treatment beam, the second positioning means holder in its first orientation forming said receiver means.

31. The apparatus of claim 23 further including means for producing a second treatment beam spaced apart from the first mentioned treatment beam and a second positioning means associated with said second treatment beam in like manner as said first mentioned positioning means are associated with said first mentioned treatment beam, said apparatus including transfer means comprising said receiver means for transferring said item from said first mentioned positioning means in its second orientation to said second positioning means in its first orientation.

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