Lifting device, wafer conveyance robot, and wafer conveyance system

Abstract

To implement a lifting device that enables stable long-stroking with a small-sized and simple configuration.SOLUTION: A lifting device comprises: a ball screw spline shaft 13 with which a first ball screw nut 11 and a spline nut 12 are engaged; a ball screw shaft 15 with which a second ball screw nut 14 is engaged and which is arranged together with the ball screw spline shaft 13; and a motor 16 for rotating and driving the ball screw spline shaft 13. The first ball screw nut 11 is moved up and down by screw feeding by the ball screw spline shaft 13. The spline nut 12 includes an outer ring 12b that is moved up and down integrally with the first ball screw nut 11 and an inner ring 12a that rotates together with the ball screw spline shaft 13. The ball screw shaft 15 is moved up and down integrally with the outer ring 12b of the spline nut 12 and rotates by receiving the rotation of the inner ring 12a of the spline nut 12. The second ball screw nut 14 is moved up and down by screw feeding by the ball screw shaft 15.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a lifting device, a wafer transfer robot, and a wafer transfer system that achieve a long stroke with a small and simple configuration.

Background Art

[0002] This type of wafer transfer robot is arranged in a transfer chamber such as an EFEM (Equipment Front End Module), and covers the necessary movable range by traveling along rails, extending and retracting the robot hand, lifting and lowering operations, etc. A ball screw mechanism is generally adopted for the lifting mechanism that lifts and lowers the robot.

[0003] By the way, in recent years, there has been a demand for a longer stroke and smaller size in the Z-axis direction of the wafer transfer robot. However, with a simple ball screw mechanism, even if it is desired to extend the stroke of the robot, it is not possible to simply extend the length of the ball screw unless the overall length of the robot itself is extended.

[0004] In order to solve such problems, for example, those disclosed in Patent Documents 1 and 2 can be considered available.

[0005] In any of the documents, a telescopic structure is realized using a pulley and a lifting belt. Specifically, the first-stage and third-stage housings are connected by a lifting belt, and a pulley is attached to the second-stage housing to serve as a movable pulley.

[0006] In this state, when the second stage is lifted or lowered with respect to the first stage by ball screw lifting or the like, the third stage can be simultaneously lifted or lowered by the lifting belt, and it is possible to double the stroke.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] However, any telescopic mechanism requires a structure and space for winding pulleys and wires, and it is necessary to secure a wide inner space of the housing. For this reason, there are problems that the mechanism becomes complicated and the entire mechanism becomes large-sized. Moreover, in the case of an elevating belt structure, the rigidity is low, vibration is likely to occur, and belt breakage or the like is also likely to occur, so it is difficult to perform accurate operations over a long period of time.

[0009] The present invention has been made paying attention to such problems, and an object thereof is to realize an elevating device, a wafer transfer robot, and a wafer transfer system that can achieve stable long stroke with a small and simple configuration. [Means for Solving the Problems]

[0010] The present invention has taken the following means in order to achieve such an object.

[0011] That is, the elevating device of the present invention includes a ball screw spline shaft in which a first ball screw nut and a spline nut are engaged, a ball screw shaft in which a second ball screw nut is engaged and provided side by side with the ball screw spline shaft, and a motor for rotationally driving the ball screw spline shaft. The first ball screw nut is screw-fed on the ball screw spline shaft to move up and down, the outer ring of the spline nut moves up and down integrally with the first ball screw nut, and the inner ring rotates together with the ball screw spline shaft. The ball screw shaft moves up and down integrally with the outer ring of the spline nut and rotates receiving the rotation of the inner ring of the spline nut, and the second ball screw nut is screw-fed on the ball screw shaft to move up and down. This is the gist of the invention.

[0012] In this way, with respect to the screw feed amount of the first ball screw nut, the second ball screw nut is further screwed from the position of the first ball screw nut, so that the lifting motion appears in two stages. And since the present invention can reduce the number of shafts by using a ball screw spline shaft, the mechanism part can be simplified and an increase in size can be avoided. Also, since only the calculation for two stages of the screw feed mechanism is required and there is no additional mechanism such as a lifting belt, the design cost can be suppressed. Furthermore, in the case of a lifting belt structure, the rigidity is low, vibration is likely to occur, and belt breakage etc. are also likely to occur, but since the lifting belt is not used, these problems can be solved.

[0013] The ball screw spline shaft is attached to the base housing, a first movable housing is attached so as to move up and down integrally with the first ball screw nut, the spline nut, and the ball screw shaft, and a second movable housing is attached so as to move up and down integrally with the second ball screw nut. The second movable housing has a hollow portion inside the side wall, and it is preferable that the ball screw spline shaft and the ball screw shaft are disposed outside the hollow portion.

[0014] In this way, the first housing and the second housing can be telescopically operated with respect to the base housing, and a space for routing wiring can be effectively secured in the hollow portion.

[0015] At that time, it is preferable to provide a first linear guide between the base housing and the first movable housing, and a second linear guide between the first movable housing and the second movable housing.

[0016] In this way, even without taking measures such as arranging a plurality of ball screw spline shafts and ball screw shafts side by side for each stage to prevent collapse, it is possible to appropriately prevent a collapse moment from acting on the ball screw spline shaft and the ball screw shaft, so that the simplification of the mechanism part and the miniaturization of the size can be made more effective.

[0017] The ball screw spline shaft provided with the first ball screw nut and the spring nut may be provided in multiple stages in front of the ball screw shaft provided with the second ball screw nut, and telescopic movement may be further enabled between the multiple stages of ball screw spline shafts.

[0018] In this way, a telescopic mechanism with three or more stages can also be effectively configured.

[0019] By using the above lifting device, making the second movable housing rotatable with respect to the first movable housing, arranging a turning shaft motor outside the second movable housing, and attaching an arm mechanism to the second movable housing to form a wafer transfer robot, a robot with a small footprint can be realized, and a space for routing wiring can be effectively secured inside the second movable housing.

[0020] And it is preferable to configure a wafer transfer system by arranging such a wafer transfer robot to travel along a rail provided in a transfer chamber.

[0021] When incorporated into the transfer system, the space-saving arrangement of the robot enables the wiring connected to the robot to be accommodated in the available space, and effectively eliminates the problem of wiring damage due to rubbing.

Advantages of the Invention

[0022] According to the present invention described above, it is possible to provide a lifting device, a wafer transfer robot, and a wafer transfer system that are small in size, simple in configuration, and capable of achieving a stable long stroke.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0025] FIG. 1 shows a wafer transfer robot 100 to which the lifting device 1 of this embodiment is applied.

[0026] This wafer transfer robot 100 is assembled with an articulated arm mechanism 102 on a base 101, and the base 101 can be lifted and lowered by a lifting device 1 using a telescopic mechanism with a ball screw spline.

[0027] As shown in FIGS. 1 to 4, the lifting device 1 includes a ball screw spline shaft 13 in which a first ball screw nut 11 and a spline nut 12 are engaged, a ball screw shaft 15 in which a second ball screw nut 14 is engaged and which is provided beside the ball screw spline shaft 13, and a motor 16 for rotationally driving the ball screw spline shaft 13.

[0028] As shown in FIGS. 3, 4, and 5, the ball screw spline shaft 13 is rotatably attached to the base housing 21. The base housing 21 is composed of a bottom wall 21a, a top wall 21b, and side walls 21c having a substantially U-shaped cross section. The ball screw spline shaft 13 is rotatably provided between the bottom wall 21a and the top wall 21b via a bearing 13B, and a pulley 13a is integrally rotatably provided at the lower end. The pulley 13a is driven by a driving force input via a belt 16a from a motor 16 provided at a position away from the bottom wall 21a.

[0029] As shown in FIGS. 3, 4, and 6, the first ball screw nut 11 is screwed onto the ball screw spline shaft 13, and this first ball screw nut 11 is integrally provided on the housing 10. First linear guide elements 31a are provided on the partition walls located on both sides of the ball screw nut 11 in the side walls 21c of the base housing 21. A first linear guide element 31b provided at a corresponding position of the housing 10 is engaged with the first linear guide element 31a so as to be able to move up and down to constitute a first linear guide 31. Further, a side wall 22c of the first movable housing 22 is attached to the housing 10. Therefore, the first ball screw nut 11 is screw-fed onto the ball screw spline shaft 13 together with the housing 10 and the first movable housing 22.

[0030] As shown in FIG. 4, the spline nut 12 has an inner ring 12a and an outer ring 12b, and balls (not shown) are arranged at appropriate positions. The outer ring 12b is configured to be integrally with the housing 10 and move up and down without rotation. The inner ring 12b of the spline nut 12 is configured to rotate integrally with the ball screw spline shaft 13 while moving up and down together with the outer ring 12a. A second pulley 12c is attached to this inner ring 12a.

[0031] On the other hand, as shown in FIGS. 1 to 3, 4, 6, etc., the first movable housing 22 is composed of a bottom wall 22a, a top wall 22b, and side walls 22c having a substantially U-shaped cross section. The ball screw shaft 15 is rotatably provided between the bottom wall 22a and the top wall 22b via a bearing 15B. The bearing 15B is attached to a part of the housing 10.

[0032] Then, a third pulley 15a is provided at the lower end of the ball screw shaft 15 so as to be integrally rotatable, and the third pulley 15a and the second pulley 12c are connected via a second belt 16b. Therefore, the third pulley 15a is integrally moved up and down with the outer ring 12b of the spline nut 12, and is rotatable by receiving the rotation of the inner ring 12a of the spline nut 12. The pulley ratios of the pulleys 12c and 15a here are 1:1. Of course, the pulley ratio can be set as appropriate.

[0033] As shown in FIGS. 1 to 3, FIG. 4, FIG. 7, etc., the second ball screw nut 14 is screwed onto the ball screw shaft 15, and a side wall 23c of the second movable housing 23 is attached to a part thereof, and is integrally moved up and down with the second movable housing 23 by screw feed on the ball screw shaft 15.

[0034] For this purpose, a second linear guide element 32a is provided on a part of the side wall 22c of the first movable housing 22, and a second linear guide element 32b is provided at a corresponding position on the side wall 23c of the second movable housing 23, and these linear guides 32a and 32b are engaged so as to be movable up and down to constitute a second linear guide 32.

[0035] As shown in FIG. 1, etc., the articulated arm mechanism 102 has a first arm 121 via a first shaft 121a serving as a shoulder joint, a second arm 122 via a second shaft 122a serving as an elbow joint, and a hand 123 via a third shaft 123a serving as a wrist joint, respectively, and are connected in series so as to be drivable. The second movable housing 23 corresponds to the base 101. Inside the first arm 121, the second arm 122, and the hand 123, drive mechanisms (not shown) for driving the first shaft 121a, the second shaft 122a, and the third shaft 123a are incorporated, respectively.

[0036] The second movable housing 23 is provided rotatably and vertically movably with respect to the first movable housing 22. Specifically, as shown in FIG. 10, the bottom wall 23a of the second movable housing 23 is rotatably supported by a swivel shaft bracket 23y via a swivel shaft 23x, and this swivel shaft bracket 23y is vertically movably attached to the aforementioned second linear guide element 32b. The second linear guide element 32b is provided outside the second movable housing 23, and the swivel shaft 23x can be driven by a swivel shaft motor 23M disposed below the bottom wall 23a of the second movable housing 23. The swivel shaft motor 23M is composed of a speed reducer 23m1 and a motor body 23m2 that drives this speed reducer 23m1.

[0037] An arm base plate 120 to which a pair of the aforementioned articulated arm mechanisms 102 are assembled is attached to the top wall 23b of the second movable housing 23, and the articulated arm mechanism 102 is configured to perform vertical and telescopic operations from a rotated position. The arm base plate 120 rotatably assembles the first shafts 121a (see FIG. 1) of the pair of articulated arm mechanisms 102. The first shaft 121a has a hollow structure, and the wirings of the articulated arm mechanism 102 are drawn into the hollow portion 23S inside the second movable housing 23 through the first shaft 121a and a through portion (not shown) provided in the top plate 23b of the second movable housing 23.

[0038] The swivel shaft 23x of the second movable housing 23 is below the bottom wall 23a of the second movable housing 23, does not extend into the hollow portion 23S of the second movable housing 23, and the swivel shaft motor 23M is also provided below the bottom wall 23a of the second movable housing 23. The linear guide element 23b is also assembled outside the hollow portion 23S of the second movable housing 23. Also, the ball screw spline shaft 13 and the ball screw shaft 15 shown in FIG. 1 and the like are, of course, outside the hollow portion 23S of the second movable housing 23. Therefore, mechanical element parts are basically not incorporated into the internal space of the hollow portion 23S of the second movable housing 23, and it is a space that is almost entirely liberated. In this embodiment, the wirings C are neatly arranged in this hollow portion 23S.

[0039] For the wirings C, an appropriate wiring slack is ensured so that stresses caused by pulling, slackening, and twisting do not occur due to the operations of the multi-joint arm mechanism 121, and the lifting and turning operations of the second movable housing 23.

[0040] A pipe member 23x penetrates through the bottom wall 23a of the second movable housing 23, and the wirings C are drawn out below the second movable housing 23 through the pipe member 23x. The drawn-out wirings C are connected to an external power supply at the drawn-out end while ensuring an appropriate wiring slack here so that stresses caused by pulling, slackening, and twisting do not occur due to the lifting operation of the first movable housing 22 with respect to the base housing 21 and the lifting and turning operations of the second movable housing 23.

[0041] If a robot is not placed on the second movable housing 23, it is not necessary to accommodate such wirings C in the hollow portion 23S, so a lifting shaft or the like can also be arranged in the second movable housing 23. However, in this embodiment, since the multi-joint arm mechanism 121 is arranged on the second movable housing 23, a structure is adopted in which the hollow portion 23S is formed inside the second movable housing 23 and the wirings C of the multi-joint arm mechanism 102 are accommodated in the second movable housing 23.

[0042] Then, as shown in FIG. 11, this wafer transfer robot 100 is arranged to be movable along rails R1 and R2 provided in the transfer chamber 200, thereby constituting a wafer transfer system WTS. The robot 100 is configured to receive power supply through a cable (not shown) while moving along the rails R1 and R2.

[0043] A load port 301 and a load lock chamber 302 are connected to the transfer chamber 200 of the wafer transfer system WTS. When a FOUP 303, which is a wafer storage container, is arranged at the load port 301, the robot 100 performs an operation of taking out the wafers stored in the FOUP 303 and transferring them to the load lock chamber 302.

[0044] The hoop 303 has a multi-tiered shelf structure capable of accommodating a large number of wafers in the height direction. On the other hand, one load lock chamber 302 is usually connected to a position higher than the hoop 303 according to the application target of this wafer transfer system WTS. For this reason, the robot 100 requires a lifting mechanism as in this embodiment. For example, the wafers carried to the load lock chamber 302 are further transferred to the processing chamber 304 and subjected to appropriate processing. The processing chamber 304 may be either in a vacuum or in the atmosphere.

[0045] As described above, the lifting device 1 of this embodiment includes a ball screw spline shaft 13 in which a first ball screw nut 11 and a spline nut 12 are engaged, a ball screw shaft 15 which is engaged with a second ball screw nut 14 and provided side by side with the ball screw spline shaft 13, and a motor 16 for rotationally driving the ball screw spline shaft 13. The first ball screw nut 11 is screw-fed on the ball screw spline shaft 13 to move up and down. The outer ring 12b of the spline nut 12 moves up and down integrally with the first ball screw nut 11, and the inner ring 12a rotates together with the ball screw spline shaft 13. The ball screw shaft 15 moves up and down integrally with the outer ring 12b of the spline nut 12 and rotates receiving the rotation of the inner ring 12a of the spline nut 12. The second ball screw nut 14 is configured to be screw-fed on the ball screw shaft 15 to move up and down.

[0046] With this configuration, with respect to the screw feed amount of the first ball screw nut 11, the second ball screw nut 14 is further screw-fed from the position fed by the first ball screw nut 13. Therefore, between the time-lapse (height H0) in FIGS. 8 and 9 and the extended state (height H) in FIGS. 2 and 3, the operation of the second movable housing 23 is further amplified with respect to the operation of the first movable housing 22, and the lifting operation appears in two stages.

[0047] Moreover, in this embodiment, by using the ball screw spline shaft 13, the mechanism can be configured with a minimum number of shafts, simplifying the mechanism section and avoiding an increase in the size of the apparatus. In particular, compared with the case of configuring a telescopic mechanism with an elevating belt and pulleys as in the conventional example, and also compared with the case of configuring a similar telescopic mechanism by separately forming a ball screw shaft and a spline shaft, the effect of reducing the number of shafts and achieving miniaturization and simplification is obvious. Further, since only the two stages of such a screw feed mechanism need to be calculated and there is no additional mechanism such as an elevating belt, the design cost can be suppressed. Additionally, in the case of an elevating belt structure, the rigidity is low, vibration is likely to occur, and belt breakage is also likely to occur. However, in this embodiment, since the elevating belt is not used, these problems can be solved.

[0048] Specifically, the ball screw spline shaft 13 is attached to the base housing 21, the first movable housing 22 is attached so as to move up and down integrally with the first ball screw nut 11, the spline nut 12, and the ball screw shaft 15, and the second movable housing 23 is attached so as to move up and down integrally with the second ball screw nut 14. The second movable housing 23 has a hollow portion 23S inside the side wall, and since the ball screw spline shaft 13 and the ball screw shaft 15 are disposed outside the hollow portion 23S, the first housing 22 and the second housing 23 can be telescopically operated with respect to the base housing 21. Even if the articulated arm mechanism 102 of the robot 100 is disposed above the second movable housing 23, the wirings C can be appropriately accommodated.

[0049] Also, a first linear guide 31 is provided between the base housing 21 and the first movable housing 22, and a second linear guide 32 is provided between the first movable housing 22 and the second movable housing 23.

[0050] By doing so, even without taking measures such as arranging a plurality of ball screw spline shafts 13 and ball screw shafts 15 side by side for each stage to prevent tipping, it is possible to appropriately prevent a tipping moment from acting on the ball screw spline shafts 13 and ball screw shafts 15. Therefore, the simplification of the mechanism part and the miniaturization of the size can be made more effective.

[0051] Then, by using the lifting device 1 described above, the second movable housing 23 can be rotated relative to the first movable housing 22. The swivel shaft motor 23M is arranged outside the second movable housing 23, and the arm mechanism 101 is attached to the second movable housing 23 to constitute the wafer transfer robot 100. Therefore, a robot 100 with a small occupied area can be realized, and the wirings C can also be appropriately accommodated.

[0052] Furthermore, since the wafer transfer robot 100 is configured to travel along rails R1, R2, etc. provided in the transfer chamber 200 to form the wafer transfer system WTS, when incorporating the robot 100 into the transfer system WTS, in configuring the robot 100 to travel in the vicinity of the laid rails R1, R2, the space-saving arrangement of the robot 100 can be achieved. As a result, the wirings connected to the robot 100 can be accommodated in the empty space, and the problem of wire abrasion and damage can be effectively eliminated.

[0053] The above is an explanation of one embodiment of the present invention. However, the specific configuration of each part is not limited to only the above-described embodiment.

[0054] For example, a ball screw spline shaft provided with a first ball screw nut and a spring nut may be arranged in multiple stages in front of a ball screw shaft provided with a second ball screw nut, and a telescopic operation may be further performed between the multiple stages of ball screw spline shafts.

[0055] Specifically, as shown in FIG. 12, there is provided a front-stage ball screw spline shaft 113 in which a front-stage ball screw nut 111 and a front-stage spline nut 112 are engaged, a rear-stage ball screw spline shaft 213 in which a rear-stage ball screw nut 211 and a rear-stage spline nut 212 are engaged and which is provided side by side with the front-stage ball screw spline shaft 113, an output-stage shaft 315 disposed at the output stage after the rear-stage ball screw spline shaft 213 and having at least an output-stage ball screw nut 314, and a motor 116 for rotationally driving the front-stage ball screw spline shaft 113.

[0056] In this case, the front-stage ball screw nut 111 is screw-fed on the front-stage ball screw spline shaft 113 to move up and down. The outer ring 112a of the front-stage spline nut 112 moves up and down integrally with the front-stage ball screw nut 111, while the inner ring 112b rotates together with the front-stage ball screw spline shaft 113. The rear-stage ball screw spline shaft 213 moves up and down integrally with the outer ring 112a of the front-stage spline nut 112 and rotates receiving the rotation of the inner ring 112b of the front-stage spline nut 112. The output-stage shaft 315 moves up and down integrally with the outer ring 212a of the rear-stage spline nut 212 and rotates receiving the rotation of the inner ring 212b of the rear-stage spline nut 212. The output-stage ball screw nut 314 of the output-stage shaft 315 is screw-fed on the rear-stage ball screw shaft 315 to move up and down.

[0057] The relationship between the front stage and the rear stage may be two or more sets.

[0058] In this way, a telescopic mechanism of three or more stages can also be effectively realized.

[0059] Other configurations can also be variously modified without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0060] 1... Lifting device 11... First ball screw nut 12... Spline nut 12a... Inner ring 12b…Outer ring 13…Ball screw spline shaft 14…Second ball screw nut 15…Ball screw shaft 16…Motor 21…Base housing 22…First movable housing 23…Second movable housing 31…First linear guide 32…Second linear guide 100…Wafer transfer robot 102…Articulated arm mechanism R1, R2…Rail WTS…Wafer transfer system

Claims

1. A ball screw spline shaft in which a first ball screw nut and a spline nut are engaged, a ball screw shaft in which a second ball screw nut is engaged and provided side by side with the ball screw spline shaft, and a motor for rotationally driving the ball screw spline shaft, wherein the first ball screw nut is screw-fed on the ball screw spline shaft to move up and down, the outer ring of the spline nut moves up and down integrally with the first ball screw nut, and the inner ring rotates together with the ball screw spline shaft, the ball screw shaft moves up and down integrally with the outer ring of the spline nut and rotates by receiving the rotation of the inner ring of the spline nut, the second ball screw nut is screw-fed on the ball screw shaft to move up and down, characterized in that it is a lifting device.

2. The ball screw spline shaft is attached to a base housing, a first movable housing is attached so as to move up and down integrally with the first ball screw nut, the spline nut, and the ball screw shaft, and a second movable housing is attached so as to move up and down integrally with the second ball screw nut. The second movable housing has a hollow portion inside a side wall, and the ball screw spline shaft and the ball screw shaft are disposed outside the hollow portion. The lifting device according to claim 1.

3. A first linear guide is provided between the base housing and the first movable housing, and a second linear guide is provided between the first movable housing and the second movable housing. The lifting device according to claim 2.

4. A plurality of stages of the ball screw spline shaft including the first ball screw nut and the spring nut are provided side by side in front of the ball screw shaft including the second ball screw nut, and a telescopic operation is further performed between the plurality of stages of the ball screw spline shafts. The lifting device according to claim 2.

5. Using the lifting device according to claims 2 to 4, the second movable housing is made rotatable with respect to the first movable housing, a swivel shaft motor is disposed outside the second movable housing, and an arm mechanism is attached to the second movable housing. A wafer transfer robot characterized by this.

6. A wafer transfer system, characterized in that the wafer transfer robot according to claim 5 is configured to travel along a rail provided in a transfer chamber.

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