REDUCED EDGE CONTACT WAFER HANDLING SYSTEM AND METHOD OF RETROFITTING AND USING SAME

Abstract: A wafer handling system (200) and a method of retrofitting the system to an existing wafer handling apparatus (100) are provided that make possible a method of handling wafers (35) by contacting only a narrow area (202) of not more than two millimeters wide adjacent the edge of the wafer, which is particularly useful for backside deposition where device side contact defines an area of exclusion (202) that renders the wafer unusable in that area. The system (200) provides a chuck (201) on a wafer transfer arm (212) that holds a wafer by gravity on a segmented, upwardly facing annular surface (207, 208). A compatible annular surface (223) is provided on an aligning station chuck (216) so that wafers can be transferred by contact only with the exclusion area (202) of the wafer surface. A load arm (260) has two similarly compatible chucks (259) further provided with pneumatically actuated grippers (270) to allow the wafer to be loaded into a vertical processing apparatus (10). The wafer chucks (201, 216, 259) are retrofitted into a processing apparatus (100) in place of vacuum chucks and the vacuum lines that were provided to activate them are used for wafer detection. The electrical signals that were provided for vacuum chuck commands are utilized to actuate the grippers (270) on the transfer arm (260) so that no control software and little hardware need be altered for the retrofit.

Description: REDUCED EDGE CONTACT WAFER HANDLING SYSTEM AND METHOD OF RETROFITTING AND USING SAME This invention 1 elates to the walei handling, and pai ticulai ly to the tiansfei and holding, ot semiconductoi watei substiatesdui ing semiconductoi manufacture, more particularly, wafers of diameteis ot 200 millimeters (mm) and laiger Background of the Invention: In the semiconductoi industry, many companies manufacture equipment to process semiconductoi wafers, paiticularly silicon wafei , tor device pioduction Semiconductor water processing equipment employs automated and lobotic watei handleis foi moving the wafei s through the piocessing equipment and tor holding the waters for piocessing Wafer handlers in the industry typically involve the use of a vacuum chuck that includes a vacuum type spatula υi end effector on a robotic arm, which makes contact with the backside ot the water With the more veisatile handlers, contact with the watei is made by the vacuum chuck in a circulai area at the centei of the wafer One such wafer handling system is described in U S Patent No 5,820,329, heieby expiessly incoi poi ated by leterence herein Such water handling is typical in many wafei piocessing machines toi the pi ocessing of the device sides of the wafei s In semiconductor manutactuie, when processing ot the device side ot a watei is complete, a backside metallization layer is sometimes applied Foi some devices, the metallization layer is often gold Backside metallization with gold, and watei holdei s toi such piocesses is descnbed in the commonl) assigned and copending U S Patent Application Senal No 09/227,911, filed January 8, 1999, and hereby expressly mcoiporated by reference herein Foi backside metallization, similai processing equipment is used as is used to process the device sides ot watei s, but the wafer orientation is reversed Reversal of the oi lentation of a partially processed water would expose the devices at the centei ot the water to contact by the vacuum chuck of the watei tiansfer arm The devices usually cannot be subjected to such contact without suffering damage Foi this leason, vacuum chucks have been developed to grip the wafer along a 6 mm ring inside of the edge of the water As a result, a 6 mm I ing at the edge ot the wafer is reset ved as an exclusion zone in which the watei cannot be used for device manufacture The 6 mm ring of exclusion is needed to provide a surface area that is enough to enable a vacuum chuck to reliably hold the wafer in the vertical, horizontal and inverted onentations that aie lequned ot a handler Typically, tor a wafer of 200 mm in diametei , a 6 mm contact aiea on the walei engaged by elements ot the watei handlei along the edge ot the watei , amounts to an ai ea ot ovei 16 squaie centimeteis oi twelve peicent of the area of the wafei A need has been expressed in the lndustiy toi the contact aieas between the walei s and the water handlei s to be i educed, piefei bly to not moie than two mm ai ound the edge ot a 200 mm oi 300 mm watei A two mm exclusion zone contains an ai ea ot only about 12 square centimeters on a 200 mm wafei and 18 square centimetei s on a 300 mm water This need has not been tilled in the prior art Watei handlei s opei ate and ai e conti olled in conjunction with the operation and conti ol ot the machines ot which they ai e a pai t oi with which they interact Fundamental changes in the natui e and operation ot water handlei s, it made, may be incompatible with, and can adversely affect, the opei ation and control of the semiconductor processing machines Unless wafer handler changes are accompanied by replacement or redesign ot the machines, impact on opei ating software and on system opeiation can occui 1 hese contact ai eas typically pi event use ol the poi tion of the water bounded by the contacted ai ea tor device manufactui e, limiting the pei -watei device yield As pattern geometi ies become smallei and demands for highei per-watei y lcld become gieatci , the need toi increased useful ai ea t the watei becomes gi eatei Accordingly, there is a need toi a watei handler and a wafer handling technique that provides foi a smallei contact aiea or exclusion zone whei e contact with the wafer is allowed Theie is also a need toi such improved water handling in a way that does not impact upon the operating software and systems opei ation ot the machines with which such an impi oved handlei or handling technique is used Summary of the Invention: A pπmai y objective ot the pi esent invention is to provide tor the engaging and transfer ot a semiconductor watei for backside processing while making minimal contact with the device side of the water A particular objective ot the invention is to pi ovide for the engagement and transfer ot a semiconductoi wafei while contacting the wafei in a zone of exclusion adjacent the peπphei y ot the water, and moie particularly, where the zone ot exclusion is not more than two mm wide A turthei objective ot the present invention is to provide a method and apparatus toi the holding and transfer ot waters that is capable ot holding and transtei i ing waters ot dittei ing sizes, particularly ot diameters ot 200 mm and 300 mm, and that is capable among wafers of differing sizes Another objective of the invention is to pi ovide a water holding and transferring system that pi ovides foi l educed device side contact toi the backside pi ocessing of wafei s that is compatible w ith and can be reti otitted to, pi ocessing machines ot the pnoi art that do not otherwise have such capability A moi e particulai objective of the invention is to piovide foi the reti ofit of such a system to an existing pi ocessing machine with minimal impact on the hai dwaie ot the piocessing machine and with little or no impact on the opeiating software of the piocessing machine According to the principles ot the present invention, a wafer handling system is provided having a water transfer arm chuck, a centering station chuck and a load arm chuck which can hold and exchange wafers between chucks, watei cassettes and pi ocessing machine water holders while contacting a reduced aiea on the surface ot the watei , and which is capable ot contacting only an exclusion zone ot preferably not more than appi oximately two mm in width adjacent the periphery of the wafer on the device side ot the wafer during backside processing In certain embodiments, the watei chucks ot the transfer arm and load ai m have beveled edge i ings or edge ring segments that aie of a diameter largei than the diameter of the wafei The beveled edge rings insure that only a narrow exclusion zone on the edge ot the water comes into contact with surfaces on the chucks that suppoit the wafei Foi some applications, the centering station chuck may also be provided with such a beveled edge nng In ceitain embodiments, an end ettectoi chuck is provided on the transfer ai m The end effector is ot multiple piece consti uction to achieve gieatei flatness, uses an internal vacuum channel to determine water pi esence and has cei amic outi lggei s that ai c adjustable to accommodate waters ot dittei ing diameter, loi example, diameteis ot 200 mm and 300 mm The centering station chuck corrects water flat and crystal orientation ot the water and water centering The chuck is pi efei ably ot multiple piece consti uction and uses a vacuum channel to sense the presence of the wafer and optical sensoi s to sense the water flat orientation as the chuck rotates the water The suiface of the centei ing station chuck has lecesses such as clearance grooves to allow the outriggers of the end effectoi to successfully place oi lemove a water within an acceptable window ot the chuck orientation lelative to a home position The load ai m chuck is in some respects similai to the centering station chuck in the way that it inteiacts with the ti anstei ai m chuck but does not lotate to altei the onentation ot the watei It uses a vacuum channel to determine wafer piesence The load arm has pivotal water edge hooks or gπppei elements that gi ip the edge ot the watei within the exclusion zone The gπppei elements ai e pneumatically operated by electio-pneumatic actuators that can be lesponsive to the same electrical contiol signals that opei ate the vacuum contiols as weie the vacuum chucks of previous load arms The gripper elements of the load ai m chucks aie actuated in i csponse to the motion ot the lobot ti anstei arm in I elation to the load aim oi the load aim in relation to the wafei holdei of the processing machine The gripper elements may be pivotal gripper hooks, or in lieu ol the pivotal gnppei hooks, may be othei types ot water holding devices such rotary latches, similai to those having pivotal tollers or non-contact tabs of the described pnoi art, which can be rotated over the edge of the water to latch the water to the load arm chuck The gnppei elements allow the load arm to hold the wafei in a veitical orientation or facing downwardly and while being held in oi moved thiough some othei oi dittei ent onentations In ceitain embodiments ot the invention, a vacuum chuck equipped system is retrofitted with mechanical wafer engaging chucks, pai ticulai ly i eplacing the vacuum chucks on a transfer arm end ettectoi , a wafei centering or aligning station and a watei load ai m In such a system, the tiansfei ai m may be operable to pick up and move hoπzontally disposed waters transtei 1 ing them to and horn watei cassettes the centering or aligning station and the load ai m Also, the chuck at the centei ing and aligning station may be opei able to receive a wafer fiom the transtei ai m, to orient and align the wafer and to return the water to a centered and oriented position on the transtei ai m, also in a horizontal orientation Additionally, the load ai m chucks may be opei able to move a watei between the transfer arm chuck and a wafer holder ot the wafei processing machine oi exchange one watei with another, leoπenting the wafers between a honzontal orientation on the tianstei ai m and a veitical onentation in the water holder of the processing machine Wafei s aie held at least in pait by giavity on the horizontally disposed, upwardly facing chucks ot the tiansfer ai m and aligning station and aie held in part by gi avity on the load ai m chucks when they aie horizontally disposed and upwardly facing duπng tianster ot the watei s to and from the tiansfer ai m, and by positive water edge gπppei hooks, when being moved in other orientations In cei tain embodiments ot the invention Ihe conti ols ot the watei handling system ai e compatible with the controls ot the vacuum chuck equipped, pnoi ai t machine so that the system can be letiotitted theieto without substantial hardwaie changes and without modification to the control sottwaie ot the machine Vacuum chuck control lines aie used to sense the presence of wafers on the chucks Gripper opei ating pneumatic cylinders are operated by electi o-pneumatic solenoids that ai e conti oiled by electi ical sottwaie vacuum command signals that weie piovided for vacuum chuck operation Embodiments ot the present invention may be provided in the f 01 m of a i eti ofit kit that includes the thiee chuck assemblies configuied to leplace vacuum chucks ot the transfer aim, aligning station and load arm ot existing processing machines The method and apparatus ot the present in vention pi ovides the advantage of increasing the useful aiea ot a wafer by approximately toui percent, oi from 88% to 96% ot the area of the water, reducing by two-thirds the exclusion zone or unusable aiea ot the wafer, and providing, on average, similar increases in the number of devices produced per watei , theieby improving the productivity of the semiconductor making processes and machineiy These and othei objectives and advantages ol the piesent invention will be more readily appaient fiom the following detailed desci iption Brief Description of the Drawings: Fig. 1 is a perspective diagram lllusti ating a water handling and piocessing apparatus of the pi 101 ait to which the piesent invention is applicable Fig. 1A is an enlaiged pei spective diagram ot a portion ot Fig. 1 illustrating movements ot chuck assemblies Fig. 2 is a paitially bioken away view illustrating a pnoi art watei holder ot the canousel processing machine ot the apparatus ot Fig. 1 Fig. 2A is a detailed illustration ot a pnoi ait alternative embodiment to the latch of Fig. 2 shown in its latched position Fig. 3 is a cross-sectional view thi ough a portion of the carrousel processing machine ot the prior ait apparatus of Fig. 1 in relation to the watei transtei arm ot the apparatus of the prior art Fig.3A is a perspective view ot one embodiment of the vacuum chuck of the transfer arm of Fig. 3 used in the pnoi art toi backside piocessing Fig. 4 is a perspective view ot a watei handling system according to one embodiment ot the piesent invention, which is compatible with the pnoi ai t apparatus lllustiated in Figs. 1-3A Fig. 5 is a schematic top view ot the end ettectoi ot the walei ti anstei ai m ot the watei handling system ot Fig. 4 aligned with the water chucks ot the aligning station and the load arm Fig. 5A is a sectional view along line 5A-5A ot Fig. 5 Fig. 5B is a sectional view along line 5B-5B of Fig. 5 Fig. 5C is a sectional view along line 5C-5C of Fig. 5 Fig. 5D is a sectional view along line 5D-5D of Fig. 5. Fig.5E is a schematic top view, similar to Fig.5, illustrating the end effector of the wafer transfer arm locating a wafer on an alternative embodiment of the load arm chuck. Fig. 5F is a diagrammatic sectional view along line 5F-5F of Fig. 5E. Fig. 5G is a diagrammatic sectional view along line 5G-5G of Fig. 5E Fig. 6 is a paitial top view of the gnppei" mechanism ot the load arm chuck of Fig. 5 Fig. 7 is a cioss-sectional view along line 7-7 ot Fig. 6 lllusti ating the load ai m chuck gnppei s in a release position. Fig.7A is a cross-sectional view similai to Fig.7 illustrating the load arm chuck grippers gripping a water Fig.8 is an enlarged partial cross-sectional illustrating in more detail the load arm chuck grippers of Fig. 7A. Detailed Description: The environment of the piesent invention is a semiconductor wafer handling and piocessing apparatus 100 as diagrammatically lllustiated in Fig. 1, which is lepresentative ot the pnoi art. The apparatus 100 includes a high throughput can ousel-type vertical wafer processing machine 10 of the types illustrated and described in U.S. Patent Nos. 4,915,564 or 5,516,732, both expressly incorporated by leference herein. The invention is also applicable to other types of wafer processing machines, such as typical cluster tool type machines, toi example, and other machines in which wafers lemain horizontally and upwardly disposed throughout as well as machines in which the wafers aie moved thiough oi piocessed in other orientations However, the described embodiment is paiticularly suited for machines ot the type of apparatus 100 as described heiein, pai ticulai ly by letiohtting theieto The apparatus 100 includes an enclosuie 102, illustrated in phantom, having a clean atmospheie contained therein in which is situated the processing machine 10. The enclosure 102 has contained therein provision toi supporting two wafer cassettes 103, 104, each of which contains a rack 105 configured to support a vertical stack of horizontally oriented waters 35 in parallel spaced relationship for processing in the machine 10 The cassettes 103, 104 aie equipped with elevatoi mechanisms 106 to move the cassettes 103,104 vertically to bring each of the watei positions of the rack selectively into a transfer plane so that a wafei 35 therein can be unloaded or loaded into the selected position of the cassette The enclosure 102 also has a wafer transfer mechanism 110 therein having a wafer transfer arm 112 that is rotatable about a vertical pivot axis 115 and is extendable in the transfer plane 119. At the free end of the transfer arm 112 is a gripper or end effector 114 adapted to pick up and deposit wafers 35 from and into the cassettes 103, 104 and from and onto a centering chuck 116 of a wafer centering or aligning station 1 18 and a load arm chuck 59 at the end of a loading arm 60. The cassettes 103,104, the centering chuck 116 and the load arm chuck 59 aie positioned or positionable along a cnculai aie 1 17 about the pivot axis 1 15 of the transfer arm 1 12 The load ai m chuck 59 rotates on the longitudinal axis 121 of the load arm 60 to rotate a watei 35 held theieby between a hoi izontal oi lenlation needed to translei waters between it and the transfei ai m 112 and a veitical oi lentation needed to ti ansfer wafeis to and from a wafer holdei 30 (Fig.2) in the loadlock station 14 of the watei piocessing machine 10 The arm 60 furthei pivots about a vei tical axis 122 to transtei waters to and horn the water holder 30 in the loadlock station 14 The machine 10 includes main vacuum chambei 11, which is in the foi m ot a disc-shaped plenum enclosed between two generally cncular walls 12, 13 with a pluiality of, foi example, five, stations 14-18 spaced at even angular mtei vals aiound a cential hoi lzontal axis 19 Within the chamber 1 1 , mounted tor rotary movement on the axis 19, is a circulai index plate 20 having five cuculai openιngs 21 therein equally spaced to simultaneously align with each ot the piocessing stations 14-18 As illustrated in Fig.2, in each ot the openings 21, a seal I ing 27 is piovided, lesi ently suppoi ted on thiee equally angularly spaced leaf spnngs 28 connected to the index plate 20 Within each ot the seal nngs 27 a water holdei 30 is piovided, ngidly suppoited on a set of three cei amic msulatoi pins 29 to the seal l ing 27 The watei holdei s 30 aie each equipped to can y a watei 35 thiough each ot the piocessing stations 14-18 as the plate 20 is angularly indexed by one-titth revolution, or 72° At least one of the five stations 14- 18, tor example, station 14, is a loadlock station through which wafeis 35 are inserted into and lemoved fiom the main chamber 11 The lemaming stations 15-18 include any ol a number of types of tieatment stations, such as sputtei coating oi etching stations The main stiuctuie of each of the wafei holdeis 30 is a ring-shaped annular body 31, typically made of aluminum The body 31 has a clamp I ing 32 lesihently attached to the holdei body 31 and biased against the body by a set ot thiee equally angulai ly spaced leaf springs 36 The clamp ring 32 has an inner diametei slightly less than a watei 35 that is to be clamped A watei 35 is held in an opening 39 ot the holder body 31 by the clamp ring 32, which overlies the nm of the wafer 35 The springs 36 press the clamp ring 32 and wafer 35 against a set ot three latch clips 33, one of each of thiee latch assemblies 65 that are spaced at equal angulai inteivals aiound the opening 21 The latch assemblies 65 may be ot any ot a numbei of configuiations Those lllustiated in Fig. 2 ai e pivotally mounted to the space ai ound the holdei body 31 , and are of the type described in detail in U S Patent No 5,820,329 As shown in Fig. 2 latch clips 33 aie fixed at one end to one end of a pivot shaft 70 which is rotatably suppoi ted in a beanng (not shown) that extends thiough the body 31 ot the holder 30 At the opposite end ot the shaft 70 fiom the clip 33 the shaft is rigidly connected to a cncular disc 74, which has a pair ot holes 75 theiein with flaied openings at the leai waid facing surface of the disc 74 The holes 75 are spaced on opposite sides ot the shaft 70, at the same distance therefrom, to receive the pins 62 ot an actuatoi 61 (Fig. 3) on a load ai m 60 so that iσtation ot the actuatoi lotates the disc 74, the shaft 70 and the clip 33 about the axis of the shaft 70 The rotation of the disc 74 on the shaft 70 is limited to 90° ot lotational movement In the loading ot the holder 30 having the latch assemblies 65, the water 35 is piessed against the clamp ring 32 to move it away tiom the holder body 31 so that the latch clips 33 can be lotated between latched (phantom lines) and unlatched (solid lines) positions without the clips 33 abrading the sui tace of the wafei 33 An altei native latch assembly 65a is illustrated in Figs. 2A, which are described in U S Patent Application Serial No 09/183,503, expiessly mcoi porated by reteience herein The latch assemblies 65a, as with latch assemblies 65 described above, clamp the edge of the water 35 against the clamp ring 32 around the opening 39 in the wafer holding clamp ring 32. Each latch assembly 65a is, however, pivotally mounted to the clamp ring 32, rather than to the holder body 31. The latch assembly 65a is so mounted at a mounting post 130 fixed to the clamp ring 32. The latch assembly 65a includes a non-metallic latch body 131 pivotally mounted on the post 130 through a tungsten carbide ball bearing (not shown), and is biased against the clamp ring 32 by a conical spring (not shown) that surrounds the mounting post 130. The latch bodies 131 each have a pan of actuator pin receiving holes or slots 175 therein that are similar to the holes 75 described in connection with the latch assemblies 65 above, which are equally spaced from the mounting post 130, to receive actuator pins ot an actuator mechanism on a tianstei ai m, as described below, which operate the latch assemblies 65a. At opposite ends of the latch body 131 are rotatably mounted a pair of non-metallic rollers, including a front roller 135 and a back roller 136. Fig. 3 is a cross-sectional view through the processing machine 10, through the loadlock station 14. The loadlock station 14 includes a moveable cup-shaped closure 54, which is actuated to force the seal ring 27 against the front wall 12 of the chamber 11 to form a sealed loadlock chamber 55 at the loadlock station 14A door 56 provides access foi a wafer 35, carried by the vacuum chuck 59 of the ti ansfer or load arm 60. In the manufactuie of semiconductor devices, the load arm 60 operates to translate the water 35, device side first, into the loadlock chamber 55, through the opening in the holder body 31, to bring the outer nm of the water 35 into contact with the underside of the clamping clamp ring 32. For device side processing, the load arm chuck is a circular chuck 59a that engages the center of the backside of the water 35. The vacuum chuck 59a is connected to a selectively operable vacuum source through a vacuum line 69 in the load arm 60. When pi ocessing the backside of a wafer 35, such as where backside metallization is being carried out to deposit a continuous film ot a metal such as gold on the wafer, the wafer is inverted and chucks 59, 114, 1 16 engage the wafer 35 from the device side. Since contact between the chucks and the devices on the wafer must be avoided to prevent damage or destruction of the devices, it is necessary to restrict devices to a reserved or restricted area of the wafer 35 and to avoiding the placement of devices in an exclusion zone on the surface of the wafer. The exclusion zone has historically been an area within 6 mm of the wafer nm around the perimeter of the wafer. In this area of exclusion, arc-shaped vacuum chucks 59b, as illustrated in Fig. 3A, contact only the exclusion aiea at the edge the wafer 35. The paddle or wafer engaging end of the chucks preferably extends around a major part of the circumference of a 6 mm ring around the perimeter of the wafer. Insertion ot the wafer 35 into the holder 30 is carried out with the latch clips 33 rotated out of the path of the wafer 35. Rotation of the latch clips 33 into and out of position behind the wafer 35 is accomplished by three latch actuatoi s 61 carried by the transfer or load arm 60, also as illustrated in Fig.3. The latch actuators 61 each include a pair of actuator pins 62 on the shaft of a pneumatically actuatable rotary cylinder 63, which, when the pins 62 are in engagement with a corresponding one of three latching mechanisms 65 on the holder 30, rotate 90° in one direction to simultaneously move the three clips 33 into a latching position behind the water 35, and 90° in the opposite direction to move the clips 33 to a release position in the holder beyond the nm ot the watei 35 Accoi ding to principles ot the piesent invention, a water handling and pi ocessing appai atus, such as the appai atus 100, is piovided with a watei ti anstei mechanism 210, similar to the ti ansfer mechanism 110 ot the appaiatus 100, described in connection with Fig. 1, but equipped with the wafei handling system 200, one embodiment of which is lllusti ated in Fig. 4 The system 200 includes three chucks and lelated hardware, including a ti anstei arm chuck oi end eftectoi 201 located at the end ot the transfer arm 212, which operates in the mannei of the ti anslei ai m 1 12 descι ιbed above The system 200 also includes a centering chuck 216 at the watei aligning station 118, which operates in the manner of the centering chuck 116 described above, and a pan ot load ai m chucks 259 at the end ot a load ai m 260, which operates in the manner ot the load ai m 60 descnbed above The end ettectoi 201 includes walei suppoi t sui faces that contact a downwai dly facing de\ ice side ot a horizontally disposed wafei 35 only in an exclusion zone 202 within two mm of the edge of the device side of the wafer 35 The wafer 35 lests undei the loice ot gravity on the end effector 201, which moves to move the waters 35 to and from wafei cassettes 103, 104, to and from the centering chuck 216 at the aligning station 1 18 and to and from the load arm chuck 259 on the load arm 260 Figs.5, 5A-5D illustrate the end effector 201 in detail as including a body in the form ot a transfer arm plate 203, which is hxed by screws 204 to the end ot the transtei ai m 212, and a pan of outi lgger arms 205, of trapezoidal cross-section, ngidly attached to the ti anstei ai m plate 203 b> fitting into dove tail keyways (not shown) in the plate 203 when they are held by locking washer nuts 211 The outnggeis 205 aie adjustable in the keyways to accommodate wafeis of difteient sizes The aims 205 are ceramic and have upstanding support tips 206 that contact the exclusion aiea 202 ot a watei 35 being transtened by the transtei aim 212 The plate 203 and the tips 206 have segments 207, 208, lespectively, of a circular shoulder thereon configured to support the wafei 35 at its exclusion edge 202 Immediately adjacent the shouldei segments 207, 208 are respective angulai ly oi ciicumferentially spaced segments 217, 218 ot a beveled circular lip which immediately sunounds the penpheral edge ot a water 35 being earned by the transfei arm 212 The nuts 211 aie located tangent to the lip segment 217 and have conical head surfaces 219 that form an extension ot the beveled lip, and function with the lip to guide watei s onto the shouldei segments 207, 208 The segments 217, 218 ot the beveled cncular lip and the pin head surfaces 219 serves to cause a wafer being supported thereon to immediately centei on the end effector 201 without coming to lest with the edge ot the wafer beyond the lip The inside diameter of the bevel surrounds an annular surface of the shoulder segments 207, 208 ot less than two mm in width, on which the exclusion zone 202 of the wafer 35 rests This inside diametei of the bevel equals the nominal diametei ot a standard watei , typically 200 mm or 300 mm, plus the maximum tolerance in the i adial dnection of about 0 008 inches oi about 0 2 mm so that the largest watei will lest inside ot the beveled cuculai lip 1 he outnggei s 203 aie secuied to the plate 202 in part by washer nuts 21 1 The conical side surfaces ot the heads 219 ot the nuts 211 extend the bevel of segments 217, 218 above the upper sui faces of the plate 203 to assist in guiding a wafer 35 onto the circular aiea sun ounded by the segments 217, 218 of the beveled lip when the wafei 35 are picked up tiom the cassettes 103, 104 The bevels on the chuck use above the support surface of the chuck a distance ot at least the nominal thickness ot a watei and pieteiably about one mm The angle ot the bevel is piefei ably about 45°, plus or minus 10° oi 15° The bevel does not have to be all the way around the support surface but can be at a plui ality ot points, pi efei ably three or more points spanning more than 180°, and pieterably tour points The outπggei s 205 aie sufficiently thin to reach between wafei s 35 stacked in the cassettes 103,104 toi removal and replacement ot the wafers As lllustiated in Fig. 5, the outι ιggeι s 205 also aie dimensioned to fit into grooves 221,222 in the sui face ot the centei ing chuck 216 at the centei ing station 1 18 I he centei ing chuck 216 ha a lυwu disk shaped body 216a and a segmented upstanding edge i ing 223, which is semicirculai to ieceive a water 35 fiom the end ettectoi 201, that can lift and lotate the watei on the end effector 201 to bring a flat or notch 235 (Fig. 5) on the water 35 to a piedetei mined onentation coπesponding to a flat 224 on the centering chuck 216 The edge ring 223 may be beveled, as with the transfer arm chuck, to guide the water into contact with the suppoiting sui faces ot the chuck only in the exclusion area of the water, but the absence of beveling may be moie compatible with the centering mechanism and function In the embodiment shown, the edge i ing 223 at the centei ing station has an innei surface perpendicular to the plane of the wafei At the centering station optical sensoi s on the centering chuck 216 (not shown) determine the wafer orientation Also as illustrated in Figs. 5, the load ai m chucks 259 each have a chuck plate oi body 261 having giooves 262,263 therein to receive the outπggeis 205 of the end effector 201 The chucks 259 take the place ot the device side engaging vacuum chuck 59b ot Fig. 3A The plate 261 has an upstanding segmented partially cncular lip 265 around its edge on which lests an exclusion zone aiound the edge of the watei 35 The lip 265 is beveled, as with the tianstei ai m chuck and centei ing station chuck descnbed above, to insuie that the device side contact is made only with the exclusion zone thai is not moi e than two As illustrated in Figs. 6, 7, 7A, and 8, at spaced inteivals aiound the lip 265 is a plui a ty ot gπppei s or gπpper fingei s 270, for example two to tour in number, each pivotally mounted on a rod 281 that is suppoited in beaπngs to the body 261 ot the load arm chuck 259 The grippers 270 each have a notch 273 theiein to captuie the peπphei al edge ol the water 35 The grippers 270 each have an operating lever 271 that is conti oiled by an actuatoi 272 mounted on the load ai m chuck 259, which opeiates in response to the vacuum commands provided thiough the line 69 to control the vacuum to operate the vacuum chucks 59, 59a ot the prior art system, but which chucks have been lemoved and leplaced with the mechanical load arm chucks 259 The actuatoi 272 may be an electrically or pneumatically controlled pneumatic cylinder, an electi ical-mechanical solenoid or some other device for moving the grippers 270 between the released and gripping positions ot Figs. 7 and 7A Further, as best seen in Fig. 8, vacuum ports 295 are also provided in the chuck body 261 to connect to a series of holes (not shown) in the lip 265 to piovide for the sensing of a properly seated water 35 in the chuck 259 The actuator 272 has a body 282 lixed to the body 261 of the load arm chuck 259 and a moveable element 283 that reciprocates in a dnection pei endiculai to the body 261 between a i en cted position (Fig. 7) pi oximate the body 261 in which the gπppers 270 are in their released position and an extended position (Fig. 7A) away tiom the body 261 in which the gπppeιs 270 are in their gπpping position Fixed to the end of the moveable element 283 ol the actuatoi 272 is an actuatoi bar 284, which extends pai allel to the body 261 and moves with the element 283 The operating lever 271 of each gripper 270 has a fork 285 at thereon having an adjustable set screw 286 threaded therein. The set screw has an eye 287 therethrough in which is hooked a soft spi ing 288, which is connected in tension between the set screw 286 and a remote end ot the actuator bar 284. The spring 288 functions to limit the amount of force that can be exerted by the gnpper 270 against the backside of the wafer 35 in clamping the wafer 35 against the lip 265 ot the chuck 259. The set screw 286 is piovided so that this limit can be manually adjusted The each operating lever 271 also has a link 289 extending theiefrom, which are pivotally joined togethei at their remote ends with a fol k 290 in the end of one pivoting and sliding on a bearing 291 in the end of the other. The interconnection ot the ends ot the links 289 synchronizes the motion of the grippers 270 In lieu of the gπppers 270, other elements can be used to latch the wafer to the load aim. Rotatable latches having i ollei s or fingei s, toi example, such as those described in connection with the prior ait described and incorporated by reference above, can be used. These can also be operated by pneumatically opei ated actuatois 61 or by mechanical or other devices For example, Fig. 5E lllustiates an alternative embodiment 300 to the load arm chuck 259, that employs support of the water 35 on thiee edge supports that include a fixed pin 301 and two rollers 302. The load ai m chuck 300 of this embodiment is lllusti ated in a form configured for the support of 300 mm wafers without an edge flat 235 of the embodiment shown in Fig. 5. Alternatively, a wafer 35 with a flat or notch may be placed on the chuck 300 with the flat oi notch oriented to miss the fixed pin 301 and rollers 302 The chuck 300 may be employed as a load ai m chuck oi a centering station chuck. The chuck 300 provides contact with three or more points on the edge of the water 35, and includes, tor example, a housing 307 to which is mounted a lixed pin 301 and a pair of concave or notched rollers 302 The rollers 302 are mounted to the housing 307 so as to latch against and letract from the edge ot the water 35 The chuck 300 is configuied such that the transfer arm chuck or end effector 201 can deliver the wafer 35 to the chuck 300 by advancing the water edgewise between the two rollers 302, when they are in retracted positions, and against the fixed pin 301 The rollei s 302 are located opposite the centei line 303 of the chuck 300 from the fixed pin 301, with the iσlleis being spaced at an angle 304 of preferably at least 160° apait, but less than 180° apart. An angle of less than 160° is acceptable depending on the design of the end effector 201 When the chuck 300 is upwaidly lacing, the fixed pin 301 has a honzontal sui face 31 1 to support the edge of the wafer 35 by contacting the water 35 only within the 2 mm exclusion zone as shown, for example, in Fig. 5F The pin 301 has an overhanging inclined and nearly vertical suiface 312 which faces radially inwardly toward the center ot the watei 35 The rollers 302 may be mounted on pivotal levers 302a so as to swing, in response to the motion ot the actuators 61 , between retracted positions away from the edge of the wafer 35 to latching positions against the edge of the water 35, as illustrated in Fig. 5E Alternatively, the rollers 302 can be pivoted in response to other actuators that respond to the signal that was toi merly used to contiol the vacuum chuck, as in the case ot the actuators 272 toi the gπppei fingers 270 in the embodiments discussed above The lollei s 302 have smooth concave sui taces 315 to ti ap the edge ot the wafei 35 when in the latching positions, at which the watei 35 is picked up tiom the end ettectoi 201 The concave suitaces 315 ot the toilets 302 and the combined inclined surface 312 and hoi lzontal sui face 311 ot the fixed pin 301 ti ap the walei 35 on the chuck 300 so that the wafei 35 can be lotated to a vei tical onentation oi downwai dly facing onentation, and ti ansteπed to and tiom a watei holder 30 The load arm chuck provides toi the coπect placement of the wafer into the wafer processing machine Attei being so positioned into a vacant watei holdei 30 within the loadlock of the processing machine, the grippers or latches lelease the watei while the watei holder simultaneously is grasping the wafei The opposite sequence is used to remove a wafer from the loadlock When the load arm chuck withdraws from the water holder, the pi ocessing machine can index the next wafer holder into the loadlock With two chucks on the load arm, the load arm checks for the presence ot a water in the water holder at the loadlock and, it one is pi esent, removes the watei with an empty chuck on the load arm Then, the load aim rotates 180° to bi ing a new water into position and loads it into the water holder in the loadlock The chuck that deposits the watei into the loadlock is then available to leceive the next wafei from the transfer aim end effector before lotating 180" to tiansfei the pi ocessed watei on the other chuck ot the load ai m onto the end ettectoi While the above descπption and accompanying di wings set toith vaπous embodiments ot the invention, it will be appaient to those skilled in the ait that additions and modifications may be made without depaiting fiom the pπnciples ot the invention

Claims: Accordingly, what is claimed is 1. A semiconductoi water handling system pai ticulai ly capable ot transpoi ting a semiconductoi watei having a device sui face on one side thereof a diameter, a generally cncular edge and an exclusion aiea on the device sui tace of not moie than appioximately two millimetei s wide adjacent the edge, in a wafei processing machine for piocessing while making suitace contact with the device sui face of the wafer only in the exclusion aiea theieot, the system compπsing a ti ansfei arm chuck, an aligning station chuck, a load ai m chuck, and each ot the ti anstei ai m, aligning station and load ai m chucks having a wafer support surface lying in a plane and formed ot segments ot an annular l ing having an outside diameter at least as lai ge as the diametei of the wafer and an inside diameter within at least two millimeters less than the diametei ot the watei , and each of the tiansfer ai m and load aim chucks having a bevel extending from the outside diameter of the support surface in at least a plurality of angularly spaced sections and positioned to guide the edge of a wafer onto the support surface and to pi event contact between the suppoi t sui lace of the chuck and the wafei except in the exclusion aiea 2. The system of claim 1 wherein the wafer support surface ol the tianstei ai m chuck lies in a horizontal plane and is upwaidly facing, and the transtei arm chuck includes a body conttguied toi mounting on the end ot a lobot wafei tianstei ai m ot the machine, the body having at least one of the segments ot the annular t ing thereon and at least two ai ms extending theieti om each ai m having a l emote end having at least one ot the segments of the annular ring thereon, the bevel of the ti ansfei ai chuck extending upwardly from the outside diameter of the support surface on at least one ot the sections ot each ot the body and ends of the arms, whereby the semiconductor watei handling system is operable to pick up and support by gravity with a transtei ai m chuck on the end ot a tianstei ai m a semiconductor wafer having its device surface facing downwardly with the exclusion aiea theieot making sui face contact with the sections of the support surface on the body and ends ot the ai ms and with the bevel outside ol the diameter ot the watei adjacent each of sections ot the support surface 3. The system ot claim 1 wherein the water support suitace ot the transfer aim chuck lies in a horizontal plane and is upwardly facing, the bevel extends upwaidly and outwaidly from the outside diameter ot the support surface, and the ti anstei arm chuck is configuied to pick up and support by gravity a semiconductor wafer having its device suitace facing downwaidly with the exclusion aiea thereof making surface contact with the sections ot the suppoi t surface and with the bevel outside of the diametei of the water adjacent each of sections ot the support suitace so as to lesti ict contact ot the device surface of the wafei by the support suitace to the exclusion ai ea ot the watei 4. The system of claim 3 wheiein the tiansfer ai m chuck includes vacuum ports positioned on the suppoiting suitace so as to be blocked by the exclusion zone of the suitace ot the water so as to activate a watei piesence detectoi when connected theieto 5. The system ot claim 1 fui ther compi ising an aligning station chuck having a wafei suppoit sui face lying in a plane and foi med of segments ot an annulai ring having an outside diametei at least as large as the diameter ot the watei and an inside diametei within at least two millimeteis less than the diametei ot the watei 6. The system of claim 5 wherein the aligning station chuck has a bevel extending tiom the outside diametei of the support sui face theieof in at least a plurality of angularly spaced sections and positioned to guide the edge of a watei onto the suppoi t surface and to prevent contact between the support surface of the chuck and the wafer except in the exclusion area 7. The system of claim 5 wherein the wafer support surface ot the aligning station chuck lies in a hoπzontal plane and is upwaidly facing, and the aligning station chuck is configured toi mounting on a wafei aligner ot the machine and has at least one recess theieon located between two sections of the supporting surface thereof to allow the tiansfei ai in chuck to extend between a wafei and the aligning station chuck to place a wafer on or pick up a wafer from the aligning station chuck, whereby the wafer aligning chuck is opei able to support by gravity tor alignment and toi pick up by the transtei ai chuck a semiconductoi watei having its device surface facing downwaidly with the exclusion aiea thereof making surface contact with the sections ot the support surface on the wafei aligning chuck 8. The system ot claim 7 wherein the aligning station chuck has a bevel extending from the outside diameter of the support surface theieof in at least a plurality ot angulai ly spaced sections and positioned to guide the edge of a water onto the support surface and to pi event contact between the suppoit sui tace ot the chuck and the watei except in the exclusion area, and the bevel ot the aligning station chuck extending upwaidly tiom the outside diametei ot the suppoi t sui face ot the aligning station chuck on the sections ot the suppoi ting sui face of the aligning station chuck, wheieby the watei aligning chuck is opei able to support the semiconductor water with the bevel ot the aligning station chuck outside ot the diameter of the wafer adjacent each of sections of the support surface theieot 9. The system of claim 1 wherein the load ai m chuck is contiguied toi mounting on a watei tianstei ai m ot the machine and has at least one recess thereon located between two sections ot the supporting surface theieot, the recess being configuied such that, when the wafer support surface of the load arm chuck is in a horizontal plane and is upwardly lacing, the ti anstei arm chuck can be extended between a water supported on the upwai dly facing suppoi ting sui face ot the load arm chuck and the load arm chuck to place a watei on oi pick up a wafer tiom the load ai m chuck, the bevel ot the load ai m chuck extending upwaidly from the outside diameter ot the suppoi t surface ot the load arm chuck, a set of moveable locking elements opei able, when engaged, to move against the backside of the wafei opposite the exclusion aiea theieof to clamp the watei against the support suitace of the load arm chuck and, when disengaged, to lelease the watei , whereby the load arm chuck is operable, when the locking elements are disengaged, to support by gravity tor pick up by the tiansfer aim chuck a semiconductor wafer having its device surface facing downwardly with the exclusion area thereof making surface contact with the sections ot the support surface on the load arm chuck and with the bevel theieot outside of the diameter ot the wafer adjacent each ot sections ot the support surface thereof 10. A method ot making a wafei handling apparatus capable of transporting a semiconductor wafei , which has a device side, a backside, a diametei and geneially circular edge, by contacting the wafer on the device side at only an exclusion area thei eot ot not moie than approximately two millimeters wide adjacent the edge, which appaiatus has at least one wafer cassette station toi holding a vertical stack of hoπzontally disposed wafers, a wafei processing machine having a load station with a walei holdei thei eat a load arm tor moving wafei s between the watei holder at the load station and a hoπzontal onentation at a tianster position, and a robot transfer arm tor moving hoπzontally oriented watei s individually among a water cassette at the water cassette station and centei ing station and the transfer position of the load arm, the method comprising attaching at least two water chucks, at least one to each of the robot transfer arm and the load arm, each chuck having a wafei support suitace lying in a plane and formed of segments ot an annular ring having an outside diameter at least as lai ge as the diametei ot the water and an inside diameter within at least two millimeteis less than the diameter ot the watei , and a bevel extending fiom the outside diametei ot the suppoi t sui tace in at least a plui hty ol angulai ly spaced sections and positioned to guide the edge ot a water onto the suppoi t sui face and to pi event contact between the suppoi t sui tace ot the chuck and the wafei except in the exclusion aiea 11. The method ot claim 10 wheiein at least one of the robot tiansfer ai m and the load ai m has a vacuum chuck thereon, and wherein at least one ot the watei chucks being attached has vacuum poits in the segments of the annulai πng theieot, and the attaching ot the watei chucks includes attaching at least one chuck by disconnecting a vacuum control line from one ot the vacuum chucks and leconnecting the vacuum control line to said ports of said wafei chuck 12. The method ot claim 11 fuithei compπsing using the reconnected vacuum conti l line in the apparatus to operate a watei piesence detectoi 13. The method ot claim 10 wheiein at least one ot the tobot tiansfer arm and load aim has a vacuum chuck thereon, and wherein at least one of the wafei chucks has latching elements theieon foi holding a wafei against the segments ot the annular ring theieot, and the attaching ot the at least one ot the watei chucks includes disconnecting a conti ol line ti om one of the vacuum chucks and reconnecting the vacuum control line to said latching elements 14. The method ot claim 10 wherein the load arm has a vacuum chuck thereon, and wherein at least one ot the watei chucks has latching elements thereon for holding a wafer against the segments ot the annular πng theieof, and the attaching of the at least one ot the water chucks includes disconnecting a vacuum control line from the vacuum chuck ot the load arm and reconnecting the vacuum control line to said latching elements 15. The method ot claim 10 wherein the load arm has a vacuum chuck thereon, and wherein at least two of the wafei chucks have latching elements thereon tor holding a wafer against the segments ot the annulai ring theieof, and the attaching of a watei chuck to the load ai m includes replacing each vacuum chuck on the load arm with one ot the at least two water chucks disconnecting a vacuum contiol line from each ot the vacuum chucks ol the load ai m and leconnecting the lespective vacuum control line to the latching elements ot a respective one of the at least two wafer chucks 16. The method of claim 10 wheiein the appaiatus also has an aligning and centei ing station toi leoπenting a water placed thereat in a hoπzontal plane, and the method turthei comprises attaching to the aligning station a watei chuck having a water support sui face lying in a plane and formed ot segments ol an annulai πng having an outside diametei at least as lai e as the diameter ot the wafer and an inside diameter within at least two millimeteis less than the diameter of the water 17. The method ot claim 16 wheiein the watei chuck attached to the aligning station has a bevel extending tiom the outside diametei ot the suppoi t suitace in at least a pluiahty of angularly spaced sections and positioned to guide the edge of a watei onto the suppoit surface and to prevent contact between the suppoit suitace ot the chuck and the watei except in the exclusion aiea 18. The method ot claim 10 wheiein the load arm of the apparatus is operable to move waters between the horizontal orientation at the transtei position and a different orientation ot the wafer holder at the load station 19. 1 he method ot claim 18 wherein the load station ot the apparatus has a vertically disposed watei holder thei eat, and the load arm is operable to move wafers between the vertical orientation of the water holder at the load station and a horizontal orientation at the transfer position 20. A water transfer method compπsing removing a hoπzontally disposed watei tiom a cassette by engaging the downwardly facing side ot the watei within approximately two millimetei s ot the edge thereof by upwardly facing water supporting surfaces ot a water chuck of a robot tianstei ai m and suppoi ting the wafer on said surfaces moving the removed water with the watei ti anstei arm to, and placing the water on, upwardly facing wafei supporting surfaces ot a wafei chuck ot a load arm by engaging the downwaidly facing side ot the watei within the appioximately two millimetei s of the edge thereof by upwaidly facing wafei supporting surfaces of the watei chuck ot the load ai m water, and latching the water to the water supporting surfaces of the wafer chuck of the load arm and tiansfei πng the latched wafer to a wafei holdei in a load station of a processing machine 21. The method ot claim 20 turthei compπsing restricting contact by the wafer suppoi ting sui faces ot at least one of the wafer chucks with a bevel extending fiom around said suppoi t surfaces to guide the edge of a water downwardly onto said support surfaces while preventing contact between said suppoit sui faces of said chuck and the watei except within the approximately two millimeters ot the watei edge 22. The method of claim 20 wheiein the moving includes fu st moving the lemoved watei with the water transfer ai m to, and placing the water on, a water chuck of a watei aligner by engaging the downwaidly facing side of the water within the two millimeters ot the edge theieot by upwaidly facing wafei suppoi ting suitaces ot the water alignei , lealigning the wafer with the wafei aligner, and letui ning the watei to the water supporting surfaces ot the watei chuck ot the robot transfer arm, and then moving the lealigned water with the watei chuck of the water transfer arm to, and placing the water on, upwardly facing wafer suppoi ting sui taces ot a water chuck ot a load arm 23. The method of claim 20 wheiein the ti anstei i ing of the latched watei includes lotating the water with the load arm to a vei tical orientation and ti anslei i ing the water to a vertically disposed wafer holder in a load station ot a piocessing machine 24. A semiconductoi watei handling system pai ticularly capable ot tiansporting a semiconductor water having a device surface on one side theieot, a diameter, a generally circular edge and an exclusion aiea on the device surface of not moie than appioximately two millimeteis wide adjacent the edge, in a water processing machine toi pi ocessing while making surface contact with the device surface of the wafer only in the exclusion area thereof, the system comprising a transfer arm chuck, an aligning station chuck, a load arm chuck, and each of the transfer arm, aligning station and load arm chucks having means for suppoi ting a watei at at least three points within not more than two millimeters of the edge of the wafer, the transfer arm chuck having a bevel extending from the outside diameter of the support surface in at least a pluiahty of angulai ly spaced sections and positioned to guide the edge ot a wafer onto the suppoi t sui face and to pi event contact between the suppoi t suitace ot the chuck and the watei except in the exclusion aiea, and the load ai m chuck oi the aligning station chuck having an inclined surface adjacent the edge of the watei at said at least thiee points 25. A method ot handling a semiconductoi watei compπsing lifting a watei , device side down, tiom a wαtei cassette with upwaidly sui taces ot a ti ansfei ai m chuck engaging the device side ot the watei within 2 millimeters ot the edge theieot, placing the water, device side down, on a load ai m chuck having surfaces that engage the wafei within 2 millimeters ot the edge theieot, gi ipping the watei to the load ai m chuck, ti ansporting the watei in, to or thiough an onentation wherein the device side of the water faces in a duection othei than down 26. The method ot claim 25 wherein the transfer arm has a bevel extending from the outside diameter of a support sui face in at least a plurality ot angulai ly spaced sections and positioned to guide the edge ot a wafer onto the support suitace and to pi event contact between the suppoit suitace ot the chuck and the water except in an exclusion aiea ot within 2 millimeters ot the edge ot the water

Inventors: COOMER STEPHEN D, KOPACZ STANISLAW, LOMBARDI MICHAEL JAMES, REYNOLDS GLYN, VISCONTI TODD MICHAEL, COOMER, STEPHEN, D., KOPACZ, STANISLAW, LOMBARDI, MICHAEL, JAMES, REYNOLDS, GLYN, VISCONTI, TODD, MICHAEL
Applicants: COOMER STEPHEN D, KOPACZ STANISLAW, LOMBARDI MICHAEL JAMES, REYNOLDS GLYN, TOKYO ELECTRON ARIZONA INC, TOKYO ELECTRON LTD, VISCONTI TODD MICHAEL, COOMER, STEPHEN, D., KOPACZ, STANISLAW, LOMBARDI, MICHAEL, JAMES, REYNOLDS, GLYN, TOKYO ELECTRON ARIZONA, INC., TOKYO ELECTRON LIMITED, VISCONTI, TODD, MICHAEL
Application year: 2001
Main classification: H01L21
IPC codes: B25J15, B65G49, H01L21