End effector and robot having end effector

Abstract

An end effector suitable for handling both wafers and wafer cassettes is described, comprising a first gripping unit configured to pick up and hold individual wafers and a second gripping unit configured to pick up and hold wafer cassettes, the first and second gripping units coupled to one another for attachment to a common robot arm and positioned at an angle to one another so as not to interfere with one another during operation.

Description

[Technical Field]

[0001] The present invention relates to an end effector and a robot having an end effector for use in the semiconductor or PV industry. [Background technology]

[0002] In the semiconductor and photovoltaic industries, it is common to subject wafers to various processes in clean rooms and ultra-clean rooms (hereafter referred to as clean rooms). These processes include batch processes as well as individual processes. They can be performed in direct succession or with a time delay between them. Between processes with a time delay, wafers are usually contained in so-called wafer cassettes (also called wafer carriers), and different types and sizes of wafer cassettes are used. Wafers and wafer cassettes are usually handled by robots, each with its own dedicated robot and its own, usually limited, footprint (floor space requirement).

[0003] Wafer robots have end effectors to pick up and hold one or more wafers and transfer them between wafer cassettes and process stations, or vice versa (possibly to another wafer cassette). However, wafer robots can also transfer wafers directly between process stations. When transferring wafers to or from a wafer cassette, they are typically positioned at specific loading and / or unloading locations. Because wafers are generally always transferred from the same location to the same location, wafer robot control is simplified. Wafer cassettes are transferred via specific cassette robots, for example, from an airlock to a loading and / or unloading location. Transferring wafer cassettes of different types or sizes may require changing end effectors. Furthermore, the working paths of the two robots (wafer robot and cassette robot) overlap and must be adjusted accordingly to avoid collisions. Furthermore, each robot must be individually trained on the environment and its respective transfer location. Cassette handling is particularly important in environments with internal cassette storage. Summary of the Invention

[0004] The object of the present invention is to overcome at least one of the above-mentioned drawbacks or at least to provide an improvement. According to the present invention, this object is solved by an end effector according to claim 1 and a robot according to claim 8. Specifically, an end effector is provided that includes a first gripping unit configured to pick up and hold individual wafers and a second gripping unit configured to pick up and hold wafer cassettes. The first and second gripping units are coupled to each other so that they are attached to a common robot arm and are positioned at an angle to each other so that they do not interfere with each other during operation. Such an end effector allows a single robot to transport both wafers and wafer cassettes without the need for end effector replacement. This reduces the handling footprint and hardware and associated costs. Fewer moving parts reduces potential sources of particles and malfunctions, which is particularly advantageous for cleanroom applications. Furthermore, having a common origin and at least partially coinciding specific approach positions (wafer cassette / wafer pickup / deposit) simplifies robot learning.

[0005] In one embodiment, the first and second gripping units are arranged at an angle of approximately 180 degrees relative to each other, where it is assumed that each of the gripping units has, for example, a central axis and that they are offset by 180 degrees relative to each other.

[0006] Preferably, the first and second gripping units are connected to one another via a coupling unit, which can be connected to a common robot arm so as to connect at least one working medium connection, preferably the same connection, to the first and second gripping units for actuating the respective gripping units. The robot arm may, for example, have connections for compressed air, vacuum, and / or electricity to drive the gripping units. Preferably, the same connection can be used to control both the first and second gripping units, allowing switching between operating the first or second gripping units. The end effector may have a rotation unit, which allows the end effector to rotate to at least two positions on the robot arm, preferably back and forth, and the position of the end effector determines the readiness of the first or second gripping unit for use. Such rotation can, for example, ensure that the corresponding working medium connection is only available to the ready-to-use gripping unit. Rotation back and forth allows access to end stops, simplifying assembly. Alternatively, the end effector can be rigidly attached to the robot arm, with each gripping unit positioned solely by movement of the robot arm.

[0007] The first gripping unit is preferably configured as a vacuum gripper, a Bernoulli gripper, or an edge gripper, and can be configured as a single gripper for picking up a single wafer or as a multi-gripper for picking up multiple wafers. In one embodiment, the second gripping unit has movable jaws, the jaws preferably having a contour that can accommodate at least two different cassette sizes or types with the same amount of movement. This eliminates the need to change the end effector to handle different types / sizes of wafer cassettes. Furthermore, by setting the same behavior when training the end effector, handling of cassettes without knowing their type or size is possible. For this purpose, the contours may have, for example, contact or gripping surfaces and / or support surfaces that cooperate with the wafer cassette and are offset in the direction of jaw movement (opening / closing direction). In particular, the jaws may have two support surfaces located at different levels, but also offset from each other in the direction of jaw movement. The movable claws can be adjusted, for example, via a cylinder unit that can be operated with compressed air and / or vacuum, where the claws can be mechanically biased into a gripping position to prevent the claws from opening unintentionally, for example, in the event of a working medium malfunction. The robot comprises a drive train with at its distal end at least one robotic arm carrying the aforementioned end effector. [Brief explanation of the drawings]

[0008] The present invention will now be described in more detail with reference to the drawings. [Figure 1] FIG. 1 is a schematic top view of an exemplary wafer processing system including a robot having an end effector according to the present invention. [Figure 2] FIG. 2 is a schematic perspective view of a robot having an end effector according to the present invention. [Figure 3] FIG. 3 is a perspective view of an end effector according to the present invention. [Figure 4] FIG. 4 is a perspective top view of an end effector according to the present invention. [Figure 5] FIG. 5 is a perspective view of the gripping claws when gripping the first type wafer cassette. [Figure 6]FIG. 6 is a perspective view of the gripping claws according to FIG. 5 when gripping a second type wafer cassette. [Figure 7] 7A-7C are perspective views of an alternative end effector in different operating positions. [Figure 8] 8A-8C are perspective views of an alternative end effector in different operating positions. DETAILED DESCRIPTION OF THE INVENTION

[0009] Relative terms such as left, right, top, bottom, etc. used in the following description refer to the drawings and are intended to indicate preferred orientations but are not intended to limit the present application in any way. The term "substantially" is intended to cover customary deviations of no more than 5%, and in terms of angular ranges, to cover deviations of up to 2 degrees.

[0010] FIG. 1 shows a schematic top view of an exemplary wafer processing system 1, which includes a housing 3, two airlock units 4 and 5, a process unit 7, cassette holding units 9 and 10, and a robot 12 having an end effector 13.

[0011] The housing 3 of the exemplary wafer processing system 1 has a rectangular base with two longitudinal and two lateral sides. The housing is configured to provide a clean room atmosphere within, and the wafer processing system 1 itself can be located within a clean room. Two cassette airlocks 4 and 5 are attached to one lateral side, through which wafer cassettes can be loaded into and unloaded from the housing, as is known in the art. In this embodiment, a distinction is made between wafer cassettes for unprocessed wafers and wafer cassettes for processed wafers. The wafer cassettes for unprocessed wafers are, for example, those for long-term wafer storage, while the wafer cassettes for processed wafers are essentially transport cassettes used to directly transport wafers to subsequent processes. The wafer cassettes for unprocessed wafers are loaded and unloaded, for example, through airlock 4, while the wafer cassettes for processed wafers are loaded and unloaded through airlock 5. Both locks can also be used for loading and unloading cassettes. The wafer cassettes can be of different dimensions, as described in more detail below. However, instead of two airlock units 4, 5, one or more airlock units can be provided, through which wafers can be supplied and / or removed, as known in the art. Alternatively, a single wafer cassette type can be used.

[0012] A process unit 7 is provided within the housing 3, in which wafers can be processed individually or in batches. The various process units are well known in the art and will not be described in detail. In the illustrated embodiment, the process unit 7 is located adjacent to the lateral side facing the airlock units 4 and 5. Those skilled in the art will recognize that other arrangements are possible and known in the art.

[0013] Two cassette holder units 9, 10 are provided adjacent to the process unit 7 and between the process unit 7 and the lateral side with the airlock units 4, 5. Wafer cassettes can be accommodated in a known manner and in defined positions on these holder units. The cassette holder units 9, 10 are arranged adjacent to the longitudinal sides of the housing 3, i.e., laterally spaced apart. In particular, in this embodiment, a cassette inserted via airlock 4 is received on the cassette holder unit 9, while a cassette inserted via airlock 5 is received on the cassette holder unit 10. Therefore, cassettes are removed in the reverse order, i.e., from the cassette holder unit 9 via the airlock 4 and from the cassette holder unit 10 via the airlock 5. The corresponding movement paths are indicated in the figure by dotted lines A, B.

[0014] A robot 12 having an end effector 13 is disposed between the process unit and the airlock unit. As shown, the robot 12 has a base 15, three rotating shafts 17, 18, and 19, two arms 22 and 23, and the end effector 13.

[0015] The base 15 is fixedly connected to the floor and houses the robot's control electronics. However, the base 15 can also be movable, with the control electronics located externally. The base supports the rotating shaft 17 so that the rotating shaft 17 is rotatable about and movable along its axis. The rotating shaft 17 is thus formed as a lift / rotation shaft. At its distal end (the end away from the base 15), the rotating shaft 17 carries a first arm 22, which is rotatably fixed to the rotating shaft 17 and thus rotates together with the rotating shaft 17 about the same axis. The first arm 22 is an elongated support element extending substantially perpendicular to the axis of rotation of the rotating shaft 17, as is known in the art.

[0016] At its distal end (the end remote from the rotating shaft 17), the first arm carries a further rotating shaft 18 having an axis of rotation that extends substantially perpendicular to the first arm and substantially parallel to the axis of rotation of the rotating shaft 17. The first arm may be provided with a drive for the rotating shaft 18, or such a drive may be integrated in the rotating shaft 18. At its distal end (the end remote from the first arm 22), the rotating shaft 18 carries a second arm 23, which is rotatably and fixedly attached to the rotating shaft 18 so as to rotate together with the rotating shaft 18 about its own axis. The second arm 23 is an elongated support element that extends substantially perpendicular to the axis of rotation of the rotating shaft 18, as is known in the art.

[0017] At its distal end (the end remote from the rotating shaft 18), the second arm carries a further rotating shaft 19 having a rotation axis extending substantially perpendicular to the second arm 23 and substantially parallel to the rotation axis of the rotating shaft 18. The second arm 23 may be provided with a drive for the rotating shaft 19, or such a drive may be integrated into the rotating shaft 19. At its distal end (the end remote from the second arm 23), the rotating shaft 19 carries the end effector 13, which is attached to the rotating shaft 19 for rotation about its axis. The rotating shafts 17, 18, and 19 may each be formed as hollow shafts through which electrical control lines and / or lines for the actuating medium for the end effector can be routed. Other robot configurations are known in the art, for example, each arm may be provided with a rotary drive for rotation about the axis of a shaft formed as a fixed shaft. Such configurations may also be used in accordance with the present invention. The drive and movable member form a drive train for the robot, which allows movement and positioning of the end effector.

[0018] The end effector 13, best shown in Figures 2 to 4, comprises a central coupling unit 25 as well as a first gripping unit 27 and a second gripping unit 28, each extending from the central coupling unit 25. The central coupling unit 25 is fixedly coupled to the rotating shaft 19 and comprises at least one connection for electrical control lines and / or actuation media to enable control of the first and second gripping units.

[0019] The first gripping unit 27 is configured as a wafer gripper and is used to transport wafers W between a wafer cassette and a process unit and / or between process units if multiple process units are provided. In the illustrated embodiment, the first gripping unit 27 is used, for example, to transport wafers from a wafer cassette on the cassette holder 9 to the process unit 7 (along the illustrated path A) and from the process unit 7 to a wafer cassette on the cassette holder 10 (along the illustrated path B). The first gripping unit 27 comprises, in a known manner, an elongated carrier 30 and a receiving unit 31. The carrier 30 is rigidly connected to the connecting unit 25 and carries the receiving unit 31 at its distal end. The carrier extends along a transversely central longitudinal axis L, which preferably intersects and extends perpendicular to the rotation axis of the rotating shaft 19. Conduits for the working medium are provided in or on the carrier 30, which conduits are connected to the connecting unit 25 via corresponding connection terminals.

[0020] The receiving unit 31 is located at the distal end of the carrier 30 and is formed by a generally C-shaped receptacle that is substantially symmetrical about the longitudinal axis L. The receiving unit 31 is preferably formed integrally with the carrier 30, but can also be formed as a separate element. The ends and apexes of the C-shape can have, for example, upwardly facing openings that are surrounded by a support ridge. The openings are connected to conduits for a working medium that can be applied to a wafer W positioned above the openings to hold it in place. For example, a vacuum can be applied through the openings to attract the wafer W against the support ridge, thereby holding and securing the wafer W. Alternatively, compressed air can be applied in a controlled manner to float and secure the wafer W by the Bernoulli effect. Alternatively, the receiving unit can be formed, for example, as a so-called edge gripper, which securely holds and secures the wafer by gripping or receiving the wafer by its edge. Such grippers and alternatives are known in the art and will not be described in further detail.

[0021] As is known, the first gripping unit may also be provided with an orientation or alignment sensor and / or a wafer rotation unit.

[0022] In the illustrated embodiment, a single first gripping unit 27 formed as a wafer gripper is provided. However, it is also possible to provide a plurality of such first gripping units 27 arranged one above the other so that multiple wafers W can be picked up simultaneously. For example, if the spacing between wafers W held in a wafer cassette and the spacing between wafers W held in a process chamber are the same, they can have a fixed spacing between them in the vertical direction. On the other hand, if the spacing between wafers W held in a wafer cassette and the spacing between wafers W held in a process chamber are different, the spacing between them in the vertical direction can be adjustable.

[0023] The second gripping unit 28 is configured as a cassette gripper and serves to transport wafer cassettes between the airlocks 4, 5 and the cassette holders 9, 10. In the illustrated embodiment, the second gripping unit 28 transports wafer cassettes, for example, from the airlock 4 to the cassette holder 9 or vice versa (along the indicated path C) and from the airlock 5 to the cassette holder 10 or vice versa (along the indicated path D). The second gripping unit 28 is attached to the connecting unit 25 at an end opposite to the first gripping unit 27. The longitudinal axis L of the first gripping unit 27 also forms the longitudinal axis of the second gripping unit 28, which extends substantially centrally in the transverse direction. When the end effector 13 is attached, the rotation axis of the rotating shaft 19 is substantially centered between the first and second gripping units 27, 28.

[0024] The second gripping unit 28 comprises an actuating unit 40 and two gripping jaws 42 connected to the actuating unit 40. The actuating unit 40 is attached to the connecting unit 25, i.e., at the end opposite the first gripping unit 27. The actuating unit 40 is attached to the connecting unit 25 and is essentially formed by a cylinder unit 44 with opposing, movable cylinders. The cylinder unit extends transversely to the longitudinal axis L and is symmetrical in this respect. As the cylinders of the cylinder unit move, their ends move substantially symmetrically with respect to the plane formed by the longitudinal axis L and the rotation axis of the rotating shaft 19. Thus, the free ends of the cylinders move uniformly away from the plane when extended and toward the plane when retracted. The cylinder unit is connected via the connecting unit to an actuating medium, such as compressed air, vacuum, and / or electricity, which controls the extension and retraction of the cylinders of the cylinder unit in the manner described above. The retraction and extension positions of the cylinder unit can be limited by stops, and these positions can be determined using an appropriate decoder. For example, the cylinder may be mechanically biased to a retracted position via a spring, whereby the actuating medium moves the cylinder against the bias, and the cylinder automatically returns to the retracted position corresponding to the gripping position in the absence of the actuating medium, as described in more detail below.

[0025] The actuation unit 40 and the coupling unit 25 may be enclosed in a common housing 45 as shown in Figures 2 to 4 .

[0026] One of the gripping jaws 42 is attached to the free end of each cylinder of the cylinder unit 44 so that they extend from the connecting unit 25 at a distance substantially parallel to the longitudinal axis L. The gripping jaws are rigidly attached to the cylinders and move with them. Therefore, as will be understood by those skilled in the art, when the cylinders are extended, the gripping jaws move symmetrically apart relative to the plane, and when the cylinders are retracted, the gripping jaws move symmetrically toward each other toward the gripping position. The gripping jaws 42 are substantially symmetrical relative to the plane formed by the longitudinal axis L and the rotation axis of the rotating shaft 19. The gripping jaws are contoured on their opposing sides to receive and grip a wafer cassette therebetween. The contour of the gripping jaws 42 matches the contour of the wafer cassette to be gripped. In particular, the contour can be selected so that two different wafer cassette types / sizes can be picked up and gripped with the same stroke of the cylinder.

[0027] In the illustrated embodiment, this is achieved by the gripping jaw 42 having two support surfaces 48, 49 and a contact surface 50 that are offset in height. The support surfaces 48, 49 extend substantially horizontally and parallel to the direction of movement of the cylinders of the cylinder unit 44. The contact surface 50 extends substantially vertically or perpendicular to the support surfaces. The support surface 48 is positioned above the contact surface 50 and extends rearward from and directly adjacent to the contact surface 50. The support surface 49 is positioned below the contact surface 50 and extends forward adjacent to the contact surface 50.

[0028] The wafer cassette to be accommodated has corresponding contours for cooperation with the wafer gripper and its respective support and contact surfaces, as will be described in more detail with reference to FIGS. 5 and 6. These figures respectively illustrate the engagement of the gripping jaws 42 with wafer cassettes 60, 60′, where different types or sizes of wafer cassettes are illustrated. At their lower ends, the wafer cassettes 60, 60′ each have a recessed region 61, 61′ extending in the longitudinal direction of the wafer cassette (perpendicular to the loading / unloading opening) and formed with laterally facing edges 64, 64′ and downwardly facing shoulders 65, 65′, respectively. The recessed regions 61, 61′ are formed in each case relative to the side walls of the wafer cassette 60, 60′ and substantially define the width of the wafer cassette 60, 60′. Supports for supporting the wafers to be accommodated are located on the inner surfaces of the side walls above the respective recessed regions 61, 61′. Therefore, the distance between the side walls can also limit the size of the wafers to be accommodated.

[0029] The distance between the outer surfaces of the sidewalls of wafer cassette 60 (FIG. 5) is different from the distance between the outer surfaces of the sidewalls of wafer cassette 60′ (FIG. 6). In particular, the distance between the outer surfaces of the sidewalls of wafer cassette 60 (FIG. 5) is smaller than the distance between the outer surfaces of the sidewalls of wafer cassette 60′ (FIG. 6). However, the distance between the outer surfaces of the laterally facing edges 64′ of wafer cassette 60′ is substantially equal to the distance between the outer surfaces of the sidewalls of wafer cassette 60. Thus, as shown in FIGS. 5 and 6, contact surface 50 of wafer gripper 42 can engage either the sidewalls or the laterally facing edges 64′ of wafer cassette 60 using the same stroke.

[0030] In the case of the wafer cassette 60 according to Fig. 5, the lower support surface 49 of the wafer gripper, which extends forward relative to the contact surface 50, can move into contact with the downwardly facing shoulder 65 of the recessed area 61 when the wafer gripper is raised, thereby enabling reliable pick-up and retention of the wafer cassette. On the other hand, in the wafer cassette 60' shown in Fig. 6, the upper support surface 48 of the wafer gripper, which extends rearward relative to the contact surface 50, can move into contact with the downwardly facing shoulder 65' of the recessed area 61' when the wafer gripper is raised, thereby enabling reliable pick-up and retention of the wafer cassette. The respective downwardly facing shoulders 65, 65' are particularly suitable for contact with the respective support surfaces 48, 49, since the shoulders are generally freely accessible (they do not function as support surfaces) and are well-defined.

[0031] The gripper jaws are therefore contoured to be able to pick up different wafer cassettes (contoured accordingly) in the same stroke. Other configurations than the one shown based on the wafer cassettes in the field are of course possible.

[0032] 7 and 8, an alternative embodiment of the end effector 13 will be described. The same reference numerals as above will be used to describe identical or similar elements. The end effector 13 again has a central connection unit 25 and a first gripping unit 27 and a second gripping unit 28 extending from the central connection unit 25, respectively. The central connection unit 25 and the first gripping unit 27 are essentially the same as in the first embodiment, and will not be described again.

[0033] The second gripping unit 28 again has an actuation unit 40 and two gripping claws 42 connected to the actuation unit 40. The actuation unit 40 can have basically the same structure as in the first embodiment.

[0034] The main difference with respect to the first embodiment is the gripping claws 42. The gripping claws 42 of the first embodiment are oriented in a substantially horizontal direction, in particular on a horizontal support surface, whereas the gripping claws 42 according to Figures 7 and 8 are oriented in a substantially vertical direction.

[0035] In particular, the gripping jaws 42 of FIGS. 7 and 8 are configured to grip a vertically extending flange of the wafer cassette 60″. Such a flange may, for example, extend beyond the height of the front side (lateral to the loading / unloading opening) of the wafer cassette 60″ and extend outward relative to the loading / unloading opening. Such a flange may already be provided on the wafer cassette in the field. The wafer cassette 60″ may be gripped by corresponding engagement with the flange. For additional support, a horizontal support (not shown) may be provided on the gripping jaws to engage the underside of the wafer cassette 60″ or a downward-facing contact surface similar to the design shown in FIGS. 5 and 6.

[0036] Although the present invention has been described above with reference to the illustrated embodiment, it is not limited to that precise embodiment, and many different embodiments will occur to those skilled in the art in light of the teachings of the present invention, particularly with regard to the specific implementation of the first and second gripping units of the end effector.

Claims

1. a first gripping unit configured to pick up and hold individual wafers; a second gripping unit configured to pick up and hold the wafer cassette; The end effector, wherein the first gripping unit and the second gripping unit are connected to each other so that they can be attached to a common robot arm, and are positioned at an angle to each other so that they do not interfere with each other during operation.

2. The end effector of claim 1 , wherein the first and second gripping units are disposed at an angle of approximately 180 degrees from each other.

3. the first and second gripping units are connected to each other via a connection unit; 3. The end effector according to claim 1 or 2, wherein the coupling unit is capable of connecting at least one connection terminal for a working medium, preferably the same connection terminal, to the first and second gripping units for actuating the respective gripping units and for coupling to a common robot arm.

4. 4. The end effector of claim 1, further comprising a rotation unit by which the end effector is mounted to the robot arm so as to be rotatable back and forth between at least two positions, the position of the end effector determining a ready-to-use state of the first or second gripping unit.

5. The end effector according to claim 1 , wherein the first gripping unit is formed as a vacuum gripper, a Bernoulli gripper, or an edge gripper.

6. 6. The end effector of claim 1, wherein the second gripping unit has movable claws whose contours are configured to accommodate at least two different wafer cassette sizes or types with the same amount of movement.

7. The end effector of claim 6 , wherein the movable claw is movable via a cylinder unit, the claw being mechanically biased to a grasping position.

8. A robot comprising a drive train with at least one robot arm, the distal end of which is mounted an end effector according to any one of claims 1 to 7.

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