Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
  • B65G25/00—Conveyors comprising a cyclically-moving, e.g. reciprocating, carrier or impeller which is disengaged from the load during the return part of its movement
  • B65G25/02—Conveyors comprising a cyclically-moving, e.g. reciprocating, carrier or impeller which is disengaged from the load during the return part of its movement the carrier or impeller having different forward and return paths of movement, e.g. walking beam conveyors
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S414/00—Material or article handling
  • Y10S414/135—Associated with semiconductor wafer handling

Definitions

• the present invention may be characterized broadly as a moving floor type of conveyor. That is, due to the motion of the floor, objects placed on the floor at one end will be transported in a more or less straight line to the opposite end of the floor.
• the specific dimensions of the conveying surface portion of the apparatus depend upon the particular application. In one application, that surface may be relatively long and narrow so that it constitutes a track for transporting small objects through a processing zone or a work station. In another application such as a truck bed, that surface may be relatively wide to enable large objects such as crates to be offloaded from the truck.
• the invention has particular application " h " connection with the transporting of relatively small, fragile articles such as semiconductor wafers through a high temperature processing zone. Accordingly, the invention will be described in that context.
• vibrating transports tend to be quite noisy so that they have a dibilitating effect on workers in the vicinity of the apparatus. Still further, vibrating transports being resonant systems can only transport objects at one speed and furthermore, they are not reversible so that the objects can only proceed in one direction on a given transport. Also such apparatus tends to be very large and massive because it requires a large support frame and a counterweight due to its mode of operation. Thus, for example, a four foot long vibratory transport weighing 100 lbs. requires a counterweight of at least 100 lbs. to provide the reaction force for the transport.
• Vibrating type transports have particularly serious disadvantages when moving lightweight, fragile objects such as semiconductor wafers. This is because they advance the objects by bouncing those objects along the surface of the transport. Particularly in a high vacuum environment, the objects actually leave the surface and become airborne and then drop back onto the surface at a slightly advanced location thereon. Thus the objects are constantly striking .the vibrating surface.
• Flat, lightweight objects such as semiconductor wafers tend to tilt as they become airborne so that the wafers often strike that surface slightly on edge causing edge chips and scratches which increase considerably the rejection rate for such wafers during processing.
• the second type of moving floor conveyor is the reciprocating slider transport described, for example, in U.S. Patent 2,973,856.
• the surface is composed of an array of sliders or slats arranged side by side with the slats being reciprocated lengthwise in groups so that at any given time more slats are being advancing than are being retracted. Consequently, articles in frictional contact with the slats are moved in the direction of the advancing slats, which are in the majority.
• That type of transport also _ has several disadvantages which militates against its use as a conveyor for the small, lightweight, fragile articles of primary interest here.
• transports of the reciprocating slider type tend to be expensive because they require a large number of cranks, links, levers and other different parts which are relatively difficult and expensive to manufacture and maintain.
• the third type of moving floor conveyor is the so-called walking beam conveyor described for example in Patent 2,644,594.
• Its transporting surface is composed of an array of slats arranged side by side and divided into groups.
• one group of slats is raised up out of a reference plane so that it engages under objects on the conveyor, is advanced a short distance and then lowered below the reference plane.
• the objects supported by that group are thus deposited onto the remaining slats at a slightly advanced location along the conveyor surface.
• the second and third slat groups are moved in the same way in succession. Thus objects on the surface are lifted up, advanced and lowered repetitively in being conveyed from one end of the surface to the other.
• a walking beam type conveyor has the same disadvantages discussed above in connection with the reciprocating slide conveyor. That is it is composed of a large number of different slides, links, levers, cranks and other such parts, all of which require lubrication, making such a conveyor totally unsuitable for use in semiconductor processing environments. So too, the walking beam conveyor is quite complex and expensive to make and maintain.
• the present invention aims to provide transport apparatus which produces minimum amounts of vibration and noise.
• Another object of the invention is to provide apparatus, of this type which can operate effectively in different hostile environments.
• Another object of the invention is to provide transport apparatus which can transport objects along a plane in either direction.
• a further object of the invention is to provide such apparatus which is relatively small, compact and lightweight.
• Another object is to provide transport apparatus which is relatively inexpensive to make and maintain.
• Still another object of the invention is to provide transport apparatus which can move fragile lightweight articles such as semiconductor wafers without damaging them. Another object is to provide such a transport which advances different objects at the same rate.
• Yet another object is to provide such apparatus which can advance a succession of objects while maintaining the spacings between them constant.
• further object of the invention is to provide such apparatus which is composed of a minimum number of moving parts.
• Another object of the invention * is to provide transport apparatus which can be used in both very dirty and very clean environments..
• a further object of the invention is to provide transport apparatus which will move articles such as semiconductor wafers without contaminating the articles or the environment surrounding the transport. Another object is to provide apparatus for transporting objects which may discriminate, between different size objects.
• the transport apparatus comprises an array of slats closely spaced side by side.
• the slats are arranged in groups with each group being supported at its
• each group of rails is, in turn, supported at its opposite ends by a pair of flexures projecting up from a common base.
• each group of slats is flexurally supported by at least one rail which is, in turn, flexurally supported above the base.
• Each group of rails is reciprocated by eccentrically driven push rods or other comparable means so that the rail group moves in an arcuate path about its connections to the base.
• the slat group corresponding to that rail group is also reciprocated so that, assuming the rail group was stationary, that group of slats would move in an arcuate path about its connections to that rail group.
• that group of rails is also moving arcuately.
• those corresponding groups of slats and rails" are reciprocated out of phase. Therefore, the resultant movement of that slat group relative to the base is a combination of the two motions, namely an orbital motion.
• each point on the slats of that group follows a generally elliptical path in space.
• the ellipse has a relatively large eccentricity and its major axis lies more or less parallel to the base so that the elliptical path is relatively long and flat.
• that group of slats orbits through a reference plane defined by the centers of the elliptical paths for all points lying on those slats with the excursions of the slats in the direction parallel to the base being relatively long relative to the excursion in the direction perpendicular to. the base.
• OMP also operated out of phase with one another so that at any given instant the different groups of slats are positioned at different locations in their orbits.
• the different slat groups execute the same orbital motion relative to the base, but follow one another.
• the different groups are reciprocated 120 degrees out of phase with one another so that the three different groups of slats are approximately 120 degrees apart in their orbital paths relative to the base.
• a relatively rigid object such as a silicon wafer whose width is commensurate with the width of the slat array is deposited onto the apparatus at one end of the slat array, it is advanced toward the opposite end of the array by the different groups of slats in succession as they execute their out-of-phase orbital motions relative to the base.
• the object Because of the shape of the orbital paths followed by the slats as described abo . ve, the object, is lifted gradually to an elevated position spaced just slightly above the reference plane, advanced a relatively long distance substantially horizontally relative to the base and then gradually lowered toward the reference plane. Whereupon, at that advanced location, the object is immediately engaged by a second group of slats and advanced in a similar fashion to be gradually lowered toward the reference plane at a point still further along in the apparatus where it is engaged by the next group of slats, and so on. Thus the.object is advanced quite rapidly. Of course, the object to be advanced cannot be too limp, because in that event, parts of the object would, sag down onto the non ' operative slats moving in the opposite direction.
• the object is raised sufficiently above the reference plane during its advancement by each group of slats such that its underside is assuredly spaced above the slats in the other groups whose motions are not in the advancing direction. Consequently, there is little likelihood of the underside of a fragile object such as a semiconductor wafer being scratched or scraped due to relative motion between the wafer and those other slats. Still, however, it is important to note that the object is never raised appreciably above the reference plane and the motions to and from that plane are quite gradual so there is ho tendency for the object to be thrown from the slats that are supporting it at any given instant. Rather the movement of the object along the transport apparatus is quite gentle. Therefore there is little or no likelihood of even very fragile articles such as semiconductor wafers becoming airborne and being damaged as they are being conveyed along by the transport apparatus even in a high vacuum environment.
• the groups of slats and rails can be reciprocated as described by means of push rods driven by a single variable-speed, reversible motor. Therefore, the apparatus can " advance objects at practically any selected speed in either direction simply by varying the speed of, or reversing, the motor. Moreover, if a succession of objects is placed on the transport apparatus, all the objects are advanced at the same rate regardless of their masses so that the spacings between the objects in the succession remain uniform. This is especially important in processing applications where the advancement of objects to or from a work station must be precisely timed for one reason or another.
• O and flexures can all be exposed to the elevated temperatures or other hostile conditions to which the semiconductor wafers are subjected in the processing zone without degrading the performance of the transport apparatus and without contaminating the environment in that zone.
• the slats, rails and flexures can all be positioned right in the chamber with the rails and slats being reciprocated by push rods extending out of the chamber by way of flexible metal bellows seals.
• the orbiting slats will transport a wafer from one end of the chamber to the other at a speed dependent upon the motor speed.
• process chambers of this type are provided with air locks at the opposite ends of the chamber to isolate the interior of the chamber from the atmosphere.
• Objects are transported into the chamber through one lock and exit the chamber through the other lock so that, as objects enter and leave the chamber, the atmospheric integrity of the chamber remains intact.
• the first transport moves objects to the air lock at the entrance end of the chamber
• the second transport conveys objects through the entrance air lock
• the third transport conveys the objects through the process chamber
• the fourth transport moves the objects through the air lock at the exit end of the chamber
• the fifth transport conveys the objects from the exit air
• each transport set can be reciprocated in unison by connecting them via bellows isolated push rods to the same driving eccentrics located exteriorly of the air locks and chamber.
• sufficient space is provided between the ends of adjacent sets of slats at the ends of the air locks to accommodate the doors or gate valves for the locks. Since the corresponding slats in each set move together, that space need not be so large that the objects cannot bridge the gap as they are transported from one set of slats to the next. However, that gap between adjacent sets of slats does prevent dirt or moisture present on one set of slats from being conveyed to the next set of slats and into the chamber.
• the " three groups of slats can be aligned endwise so as to provide a slot between adjacent sets of slats which extends across the entire width of the • transport.
• objects can be transported through an isolated process zone at a selected speed so that they remain in the zone for the required length of time. Indeed, objects can be transported to the zone at one speed and then transported through the zone at a second speed. If additional process time is required, the transport sets can be stopped so that the objects can remain the process zone indefinitely. Since the apparatus advances all objects at the same rate regardless ⁇ of size, the spacings between objects deposited on the apparatus remain constant. Consequently the location of each object is precisely determined once it is placed on the transport, thereby enabling the control of that apparatus and ancillary locks to be carried out automatically and by remote control, using conventional object position sensors.
• the present transport apparatus is quite small and compact and is composed of a relatively few, repetitive, comparatively inexpensive parts. Consequently the overall cost of the apparatus is less than prior comparable transports of this general type. Accordingly it should find wide application wherever objects have to be conveyed from one point to another either in a controlled atmosphere or in air.
• FIG. 1 is a top plan vie ' w partly in block form illustrating a semiconductor wafer process line employing orbital transport apparatus made in accordance with this invention
• FIG. 2 is a perspective view showing in greater detail a transport apparatus used in the FIG. 1 process line;
• FIG. 3 is a diagrammatic view showing in greater detail various interconnections between the components of the FIG. 2 apparatus;
• FIG. 4 is a schematic diagram illustrating one example of the motion paths of various components in the FIG. 2 apparatus;
• FIGS. 5A to 5D illustrate various motion paths produced by the FIG. 2 apparatus under different conditions
• FIG. 6 is a fragmentary perspective view of a portion of the FIG. 2 apparatus used for object path
• FIG. 7 is a side elevational view with parts cut away showing a modified transport embodiment
• FIG. 8 is a top plan view of the FIG. 7 apparatus embodiment
• FIG. 9 is a sectional view along line 9-9 of FIG.- 8.
• FIG. 10 is a sectional view along line 10-10 of FIG. 9.
• FIG. 1 of the drawings we will describe the present transport apparatus as it might be used in a process line to transport semiconductor wafers W into, through and out of a process chamber C.
• the chamber C usually contains a controlled environment. Accordingly an air lock L of wafers W are transported to the entrance air lock is opened and the wafers are transported into the process chamber C following which the gate Gamber may be controlled by stopping the wafer transport apparatus in the chamber, for a selected period of time or by selecting the transport speed and chamber length so that if the wafers are transported along the chamber at a selected rate, by the time they reach the exit end of the chamber, the process will have been completed.
• the drive section 16 is connected to the first transport apparatus 12a_ in the line 10 by a set of push rods 18. Similar sets of push rods 18 interconnect the adjacent transports 12a_ to 12e_. Also to maintain the air tight integrity of the chamber C and locks Lided in the lock and chamber walls at the points where the rods 18 penetrate the walls to provide a flexible fluid-tight seal between the rods and the lock and chamber walls. As we shall see, the illustrated line 10 requires twenty-four such bellows arranged in two layers.
• transport apparatus 12a_ to 12e_ are more or less the same except perhaps for their lengths, we will only describe transport 12a_ in detail. It comprises an array of spaced-apart parallel rails.
• the illustrated apparatus has five such rails designated R will be discussed later.
• the rails are divided into a plurality of different groups, with the rails in a given group being connected together.
• the rails Rds by cross beams 22 secured to their undersides, the beams spanning the intervening rails Rside of rail Rd blocks 26.
• the upper ends of the flexures in each set are fixed to move with the corresponding group of rails.
• the upper ends of the flexures 28 in flexure assemblies Frails Rrsides of the innermost rail group Rill referring to those same figures, an array of spaced-apart, parallel slats Sso the slats are arranged in groups similar to the groups of rails.
• slats S A second pair of beams 46 connect the second group of slats Srted above rails Rled edge 42a_ of beam 42.
• the lower end of flexure 52 is connected to the beveled edge 53a.
• Section 16 comprises a shaft 62 journalled in a pair of standards 64 projecting out from an upstanding support 65 mounted on base M.
• the shaft is rotated by a variable speed motor 66 also mounted to the base.
• Spaced apart along shaft 62 are three eccentrics 67, 68 and 69.
• Engaged around each eccentric is a circular bearing unit 70 and press fit onto the outer race of each bearing unit is a rectangular block 71.
• a long vertical block 72 is connected by a stub 63 to each block 71.
• Three pairs of push rods 18 (only three of which are shown in FIG. 1) are connected at their ends 18a_ to opposite ends of the three blocks 72.
• the opposite ends 18b_ of the pair of rods connected to each block .72 are connected to corresponding rail and slot groups by way of lower and upper flexible straps or flexures 73 and 74. Those straps permit the rods 18 to tilt as the eccentrics rotate.
• a turnbuckle 75 is positioned between each rod end 18fc> and the associated flexure 73 or 74 so that the distance between each rail or slat and block 72 can be adjusted. Those lengths determine the phase angle difference between the corresponding rail and slat groups.
• FIG. 4 illustrates diagram atically the locus of movement o£ a given point on a given group of rails, say rail Rlat S figure, when eccentric 69 is rotated counterclockwise, the supporting flexures F numbers 1 to 8 inscribed on the eccentric and on the arc A.
• FIGS. 5A to 5D illustrate four different elliptical paths E which are produced by various phase angle differences between the slats and rails in FIG. 4.
• each rail group and the corresponding slat group is governed to some extent by the lengths of the flexures in the flexure assemblies Feater variety of orbital path shapes E can be obtained by varying those flexure lengths and the eccentricity.
• the flexure assemblies Flong path E shown in FIGS. 4 and 5D has been found to work quite satisfactorily and this is produced by a phase difference between the corresponding slat and rail movements of about 20 degrees.
• an eccentricity of m about 1/8 inch provides a 1/4 inch stroke of each slat group and a 0.020 inch lift of each slat group.
• the movement paths in FIGS. 4 and 5 are drawn oversize for clarity.
• each slat group is orbited
• the slat group Sinai location of the object by a distance equal substantially to the major axis of the elliptical path E.
• the slat group S reference plane and relative to base M a distance equal to the major axis of the elliptical path E, and so on.
• the object is gradually transported horizontally relative to the reference plane and to the base M.
• each group is displaced 120 degrees in phase relative to the others. Consequently, at any given instant, the three groups of slats are positioned at different locations along the orbital path E illustrated in FIG. 4. For example, when the slat group Sioned between points 2 and * 8, below the reference plane. An instant later, the slat group Sis located between points 1 and 8 just below the reference plane.
• a wafer W or other relatively rigid object positioned on the slat array is gently engaged by a given slat group, raised gently to the elevated plane Pnced location and raises the wafer gently to the elevated plane Pthe next slat group in the array, and so on.
• the wafer W never leaves the overall slat array. Furthermore, the wafer is never moved relative to the particular group of slats in the array that is contacting the wafer at any given instant. Consequently, there is very little likelihood of the wafer becoming damaged or scratched as it is being conveyed along the apparatus. If even more gentle movement of the objects is desired, additional corresponding groups of slats and rails operating out of phase may be added to reduce the length of each incremental advance of the object.
• the transport apparatus 12a_ in FIG. 2 as well as the other apparatus illustrated in FIG. 1 can be reversed simply by reversing the motor 66 driving the eccentrics. This reverses the orbital path E followed by each slat group illustrated in FIG. 4 or FIGS. 5A to 5D causing the wafer W to be transported in the opposite direction along the apparatus. Also the speed at which the wafer W is conveyed along the transport apparatus can be varied simply by varying the speed of motor 66. In that event each slat group follows the orbital path E illustrated in FIG. 4, but at a different orbital speed.
• the objects may be removed from the transport by a similar offloading transport apparatus superimposed on, and oriented at an angle relative to, the main one.
• the slats in the main transport may be notched to accommodate the slats in the off-loading transport.
• An arrangement such as this is illustrated in FIG. 6, slats Ste slats Tual "the number and width of slats S are relatively inexpensive. Consequently, the apparatus can be manufactured at a relatively small cost as compared with vibratory and other types of transports, particularly those used for conveying small, very lightweight objects such as semiconductor wafers.
• the present apparatus is quite compact and lightweight since it requires no heavy frame or counterweight as are needed in prior vibratory transports. Also since the only motion involved in the apparatus is the orbital motion of the different track and rail groups, the apparatus produces little or no noise or vibration which might upset people and other equipment in the vicinity of the transport.
• the embodiment of the transport apparatus depicted in FIG. 2 is somewhat disadvantaged in that it is relatively high because of the requirement for the two different levels of rails and slats to achieve the
• FIGS. 7 to 10 depict a folded version of the transport apparatus which accomplishes the above objectives. Not only is that modified apparatus more compact, it also requires fewer different parts and is therefore less expensive to make.
• This embodiment also includes an array of slats Sis being designated Rflexure assemblies supports both the set of slats and the corresponding rail.
• flexure assemblies Frt rail Rd to its underside near the opposite ends of that slat.
• the rail Rparatus and the rail R and they are more or less identical.
• Each assembly includes a lower block 82 mounted to base M, the block supporting by screws 83, an upstanding flexible resilient strap or flexure 84.
• Secured to the upper end of strap 84 is an inverted L-shaped upper block 86, the short leg 86a_ of the block being connected to the strap by screws 88.
• the long leg 86b_ of that block ex ' tends down parallel to strap 84 terminating above block 82.
• the rail associated with that particular flexure assembly is connected by screws 92 to the block leg 86JD.
• the rail Re rail Reen that rail and the blocks.
• strap 96 in flexure assembly F secured by similar fasteners 102 to the left hand edge of beam 72.
• the surfaces of the block 86 and beam 72 to which the strap 96 is connected are inclined or beveled so that the strap is oriented at an angle relative to the perpendicular direction.
• the transport apparatus works satisfactorily if the included angle between the strap and the perpendicular direction is on the order of 20 degrees.
• each rail R straps 84 in the flexure assemblies associated with that rail As is apparent from FIG. 7, each rail R straps 84 in the flexure assemblies associated with that rail.
• each rail can be reciprocated and, when that is done, the rail follows an arcuate path similar to path A illustrated in FIG. 4.
• each group of slats is flexurally supported above the corresponding rail by the resilient straps 96 in the flexure assemblies associated with that group of slats. Consequently that slat group can be reciprocated relative to the associated rail so that, if the associated rail were stationary, the slat group would move along an arc similar to arc A' shown in FIG. 4.
• the slat group orbits around a generally elliptical path similar to path E depicted in FIG. 4.
• the drive section 16 includes three eccentrics 110, 112 and 114 mounted on a motor driven shaft 115.
• a push rod 116 which extends through an opening in the side wall of chamber C, the opening being sealed by a flexible metal bellows seal B connected between the chamber side wall and the push rod.
• the end of each push rod 116 inside chamber C is connected to an upstanding block 122.
• each such block is connected to one end of a flexible resilient strap 124 by means of one or more threaded fasteners 126, the opposite end of each strap 124 being secured by a fastener 128 to a block 132.
• the three blocks 132 are in turn fastened by screws 134 to the undersides of slats in the three different groups of slats.
• the block 132 connected to eccentric 110 is secured to slat Sost block 122 has a lateral extension which permits the eccentric 112 to be offset laterally
• That fixture is, in turn, affixed to the lower end of the L-shaped block 86 connected to the end of rail Rt the same time the flexure 96 is connected to that block 86 by fasteners 98.
• FIG. 7 apparatus embodiment has all of the advantages described above in connection with the
• FIG. 2 transport apparatus. ⁇
• it is quite compact and is composed of a minimum number of different parts so that it should be quite easy and inexpensive to make.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)
• Reciprocating Conveyors (AREA)

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• 1979
  • 1979-02-15 US US06/012,354 patent/US4275978A/en not_active Expired - Lifetime
• 1980
  • 1980-02-12 DE DE3034339T patent/DE3034339C2/de not_active Expired
  • 1980-02-12 WO PCT/US1980/000139 patent/WO1980001677A1/en active Application Filing
  • 1980-02-15 FR FR8003407A patent/FR2449051A1/fr active Granted
  • 1980-02-15 CA CA000345764A patent/CA1137914A/en not_active Expired
• 1982
  • 1982-10-20 CA CA000413864A patent/CA1155079A/en not_active Expired

Patent Citations (3)

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