End effector and robot having an end effector

Abstract

The invention relates to an end effector which is suitable for handling both wafers and wafer cassettes. The end effector comprises a first gripping unit which is designed to pick up and hold individual wafers, and a second gripping unit which is designed to pick up and hold a wafer cassette, the first and the second gripping units being interconnected in such a way that they can be attached to a common robotic arm and they are arranged at an angle with respect to one another so that they do not interfere with one another during operation.

Description

[0001] End effector and robot with end effector

[0002] The present invention relates to an end effector and a robot with an end effector for use in the semiconductor or PV industry.

[0003] In the semiconductor or PV industry, it is common practice to subject wafers to various processes in clean rooms or ultra-clean rooms (hereinafter referred to as clean rooms). These processes can include individual processes as well as batch processes. They can occur directly one after the other or with a time delay. Between the delayed processes, the wafers are usually held in so-called wafer cassettes, with different types and sizes of wafer cassettes being used. Typically, the wafers and wafer cassettes are handled by robots, with dedicated robots being provided for the wafers and wafer cassettes, each with its own footprint (floor space required), which is, however, usually limited.

[0004] Wafer robots have an end effector for picking up and holding one or more wafers for transporting them, for example, between a wafer cassette and a process station and back (or possibly to another wafer cassette). The wafer robot can also transport picked up wafers directly between process stations. When transporting to / from wafer cassettes, these are usually located in a designated loading and / or unloading position. Because the wafers are essentially always transported from / to the same position, the control of the wafer robot is simplified. The wafer cassettes are transported via the designated cassette robot, for example, from a lock to the loading and / or unloading position. To transport different types and / or sizes of wafer cassettes, it may be necessary to replace the end effector.Furthermore, the working paths of the two robots partially intersect, so they must be coordinated accordingly to avoid a collision. Furthermore, each robot must be individually trained for the environment and the respective transport positions. Cassette handling is particularly important in an environment with an internal stocker for the cassettes. The invention is based on the object of eliminating at least one of the above disadvantages or at least providing an improvement. According to the invention, this object is achieved by an end effector according to claim 1 and a robot according to claim 8.

[0005] In particular, an end effector is provided which has a first gripping unit which is configured to pick up and hold individual wafers, and a second gripping unit which is configured to pick up and hold a wafer cassette. The first and second gripping units are connected to one another in such a way that they can be fastened to a common robot arm and are arranged at an angle to one another such that they do not hinder one another during operation. Such an end effector enables the transport of both wafers and wafer cassettes via a single robot without the need to change the end effector. This can potentially reduce the footprint and the hardware for handling and the associated costs. Potential particle and error sources are reduced because fewer moving elements are provided, which is particularly advantageous for clean room applications. This can also potentiallysimplify the training of a robot because they have a common origin and certain approach positions (wafer cassette / wafer pick-up / deposit) at least partially coincide.

[0006] In one embodiment, the first and second gripping units are arranged at an angle of approximately 180° to each other, wherein it is assumed that the gripping units each have a central axis, for example, and that these are offset by 180° to each other.

[0007] Preferably, the first and second gripping units are connected to one another via a coupling unit, wherein the coupling unit can be connected to the common robot arm in such a way that the coupling unit has at least one connection for a working medium, preferably the same connection for the

[0008] Actuation of the respective gripping units with these. The robot arm can, for example, have a connection for compressed air, vacuum and / or electricity in order to be able to control the gripping units. In this case, the same connection can preferably be used to control both the first and the second gripping unit, wherein switching between the operation of the first or the second gripping unit can be possible. The end effector can have a rotation unit via which the end effector can be attached to the robot arm so that it can be rotated between at least two positions, preferably back and forth, wherein the position of the end effector determines the operational readiness of the first or the second gripping unit. Such a rotation could, for example, also lead to a corresponding connection of the working medium only existing to the gripping unit that is ready for use. A back and forth rotation can, if necessary, simplify the structure, since end stops can be used.Alternatively, the end effector can also be rigidly attached to the robot arm and the respective gripping unit can only be positioned via the movement of the robot arm.

[0009] The first gripping unit is preferably designed as a vacuum gripper, a bemoulli gripper, or an edge gripper. The first gripping unit can be designed as a single gripper for holding a single wafer or as a multi-gripper for holding multiple wafers.

[0010] In one embodiment, the second gripping unit has movable jaws, wherein the contour of the jaws is preferably designed such that they can accommodate at least two different cash register sizes or types with the same movement path. This makes it possible to avoid changing the end effector for handling different types / sizes of wafer cassettes. Furthermore, the same movement can be set when teaching the end effector, so that handling is possible even without knowledge of the cassette type or size. For this purpose, the contour can, for example, have contact or gripping surfaces and / or support surfaces that are offset in the direction of movement (for opening / closing) of the jaws and that cooperate with the wafer cassettes. In particular, the jaws can each have two support surfaces located on different levels, which are also offset from one another in a direction of movement of the jaws.

[0011] The movable jaws can, for example, be adjustable via a cylinder unit that can be operated with compressed air and / or vacuum, whereby the jaws can be mechanically pre-tensioned into a gripping position, for example to prevent the jaws from opening unintentionally in the event of a failure of the working medium.

[0012] Robot comprising a drive train with at least one robot arm which carries an end effector according to one of the preceding claims at its free end. The invention is explained in more detail below with reference to the drawings, in which

[0013] Fig. 1 is a schematic plan view of an exemplary wafer processing system including a robot with an end effector according to the invention;

[0014] Fig. 2 is a schematic perspective view of a robot with an end effector according to the invention;

[0015] Fig. 3 is a perspective view of an end effector according to the invention;

[0016] Fig. 4 is a perspective top view of an end effector according to the invention;

[0017] Fig. 5 is a perspective view of a gripping jaw gripping a wafer cassette of a first type;

[0018] Fig. 6 is a perspective view of the gripping jaw according to Fig. 5 when gripping a wafer cassette of a second type;

[0019] Fig. 7 and 8 perspective views of an alternative end effector in different operating positions.

[0020] The relative terms used in the following description, such as left, right, above, and below, refer to the drawings and are not intended to limit the application in any way, even though they may indicate preferred arrangements. The term "essentially" is intended to encompass typical deviations in the range of no more than 5%; with respect to angular ranges, deviations of up to 2° are included.

[0021] Fig. 1 shows a schematic plan view of an exemplary wafer processing system 1 with a housing 3, two lock units 4, 5, a processing unit 7, cassette receiving units 9, 10 and a robot 12 with an end effector 13.

[0022] The housing 3 of the exemplary wafer processing system 1 has a rectangular base with two long sides and two transverse sides. The housing is designed to provide a clean room atmosphere inside, although the wafer processing system 1 itself can also be located in a clean room. Two cassette locks 4, 5 are attached to one of the transverse sides, via 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 processed wafers. The wafer cassettes for unprocessed wafers are, for example, of a type intended for the long-term reception and storage of wafers, while the wafer cassettes for processed wafers are essentially pure transport cassettes, as they are used for the direct transport of wafers to a subsequent process.For example, the wafer cassettes for unprocessed wafers are fed in and out via lock 4, while the wafer cassettes for processed wafers are fed in and out via lock 5. It is also possible for both locks to be used for both in and out. The wafer cassettes can have different dimensions, as described in more detail below. Instead of two lock units 4, 5, however, more or even just one lock unit could be provided, through which in and / or out, as is known in the art. A single wafer cassette type could also be used.

[0023] Within the housing 3, a processing unit 7 is provided, in which wafers can be singulated or processed as a batch. Different processing units are widely known in the art and will therefore not be explained in detail. In the illustrated embodiment, the processing unit 7 is arranged adjacent to the transverse side opposite the lock units 4, 5. As one skilled in the art will recognize, other arrangements are also possible and known in the art.

[0024] Adjacent to the process unit and between the process unit 7 and the transverse side with the lock units 4, 5, two cassette receiving units 9, 10 are provided. Wafer cassettes can be received in a defined position on these in a known manner. The cassette receiving units 9, 10 are adjacent to the long sides of the housing 3, i.e., they are spaced apart in the transverse direction. In particular, in this embodiment, for example, the cassette introduced via the lock 4 can be received on the cassette receiving unit 9, while the cassette introduced via the lock 5 can be received on the cassette receiving unit 10. Accordingly, the discharge would take place in the opposite direction, i.e., from the cassette receiving unit 9 via the lock 4 and from the cassette receiving unit 10 via the lock 5. The corresponding movement paths are shown in the figure with dashed lines A, B.The robot 12 is located between the process unit and the lock units.

[0025] end effector 13. The robot 12 has, as shown, a base 15, three

[0026] Rotating shafts 17, 18, 19, two arms 22, 23 and the already mentioned end effector 13.

[0027] The base 15 is firmly connected to the floor and contains the control electronics for the robot. However, the base 15 could also be mobile and the control electronics located externally. The base supports the rotary shaft 17 such that the rotary shaft 17 can rotate about its axis and can also be moved along its axis. The rotary shaft 17 is therefore designed as a lifting / rotating shaft. At its free end (remote from the base 15), the rotary shaft 17 supports the first arm 22, which is non-rotatably attached to the rotary shaft 17 and thus rotates with it about the axis of the rotary shaft 17. The first arm 22 is an elongated support element that extends essentially perpendicular to the axis of rotation of the rotary shaft 17, as is known in the art.

[0028] The first arm carries at its free end (remote from the rotating shaft 17) another rotating shaft 18 which extends substantially perpendicular to the first arm and has an axis of rotation which runs substantially parallel to the axis of rotation of the rotating shaft 17. The first arm has a drive for the rotating shaft 18, or this can also be integrated into the rotating shaft 18. At the free end of the rotating shaft 18 (remote from the first arm 22), the latter carries the second arm 23 which is non-rotatably attached to the rotating shaft 18 and thus rotates with it about the axis of the rotating shaft 18. The second arm 23 is an elongated support element which extends substantially perpendicular to the axis of rotation of the rotating shaft 18, as is known in the art.

[0029] At its free end (away from the rotating shaft 18), the second arm carries another rotating shaft 19 which extends essentially perpendicular to the second arm 23 and which has an axis of rotation which runs essentially parallel to the axis of rotation of the rotating shaft 18. The second arm 23 has a drive for the rotating shaft 19, or this can also be integrated into the rotating shaft 19. At the free end of the rotating shaft 19 (away from the second arm 23), the latter carries the end effector 13 which is fastened to the rotating shaft 19 in such a way that it rotates with it about the axis of the rotating shaft 19. The rotating shafts 17, 18 and 19 can each be designed as hollow shafts, wherein electrical control lines and / or lines for a working medium for the end effector can run through the interior of the shafts.Other arrangements for the robot are known in the art, for example, where the respective arms have rotary drives for rotating around the axes of the shafts, which are designed as fixed shafts. Such arrangements can also be used according to the invention. The drives and movable members form a drive train for the robot, which enables movement and positioning of the end effector.

[0030] The end effector 13, which is best seen in Figures 2 to 4, has 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 connected to the rotary shaft 19 and has at least one connection for an electrical control line and / or a working medium in order to be able to control the first and second gripping units.

[0031] The first gripping unit 27 is designed as a wafer gripper and serves to transport wafers W between the wafer cassette and the process unit and / or between

[0032] Process units, if more than one process unit is provided. In the illustrated embodiment, the first gripping unit 27 serves, for example, to transport wafers from a wafer cassette on the cassette holder 9 to the process unit 7 (along the indicated path A) and from the process unit 7 to a wafer cassette on the cassette holder 10 (along the indicated path B). The first gripping unit 27 has, in a known manner, an elongated carrier 30 and a receiving unit 31.

[0033] The support 30 is rigidly connected to the coupling unit 25 and carries the receiving unit 31 at its free end. The support extends along a longitudinal axis L running centrally in the transverse direction, which preferably intersects the axis of rotation of the rotary shaft 19 and runs perpendicular thereto. A line for a working medium is provided in or on the support 30 and is coupled to the coupling unit 25 via a corresponding connection.

[0034] The holding unit 31 is located at the free end of the carrier 30 and is formed by a substantially C-shaped holder which is substantially symmetrical with respect to the longitudinal axis L. The holding unit 31 is preferably formed in one piece with the carrier 30 but can also be formed as a separate part. At the end points and the apex of the C shape, for example, upward-facing openings surrounded by a support bead can be provided. The openings are connected to the line for the working medium in order to be able to apply them to a wafer W located above in order to hold it in a defined manner. For example, a vacuum can be applied via the openings in order to pull a wafer W against the support beads and thereby hold and fix it. Controlled compressed air could also be applied in order to hold a wafer W suspended and fix it using a Bemoulli effect.Alternatively, the holding unit could also be designed as a so-called edge gripper, for example, which grips or picks up a wafer by its edge, thereby securely holding and fixing it. Such grippers and alternatives are known in the art and will therefore not be described in detail.

[0035] The first gripping unit may additionally comprise an alignment sensor and / or a wafer rotation unit, as is known.

[0036] In the illustrated embodiment, a single first gripping unit 27 designed as a wafer gripper is shown. However, it would also be possible to provide several such first gripping units 27 arranged one above the other in order to be able to pick up several wafers W simultaneously. These could have a fixed height distance from one another if, for example, the distances between wafers W held in a wafer cassette and the distances between wafers W held in a process chamber are the same. Alternatively, the height distance could also be adjustable if, for example, the distances between wafers W held in a wafer cassette and the distances between wafers W held in a process chamber are different.

[0037] The second gripping unit 28 is designed as a cassette gripper and is used to transport wafer cassettes between locks 4, 5 and cassette receptacles 9, 10. In the illustrated embodiment, the second gripping unit 28 is used, for example, to transport a wafer cassette from the lock 4 to the cassette receptacle 9 and back (along the indicated path C), as well as to transport a wafer cassette from the lock 5 to the cassette receptacle 10 and back (along the indicated path D). The second gripping unit 28 is attached to the coupling unit 25, specifically at the opposite end to the first gripping unit 27. The longitudinal axis L of the first gripping unit 27 essentially also forms a longitudinal axis of the second gripping unit 28, running centrally in the transverse direction. The axis of rotation of the rotary shaft 19, when the end effector 13 is attached, is located essentially centrally between the first and second gripping units 27, 28.The second gripping unit 28 has an actuating unit 40 and two gripping jaws 42 which are connected to the actuating unit 40. The actuating unit 40 is attached to the coupling unit 25, specifically at the opposite end to the first gripping unit 27. The actuating unit 40 is attached to the coupling unit 25 and is essentially formed by a cylinder unit 44 with oppositely movable cylinders. The cylinder unit extends transversely to the longitudinal axis L and is symmetrical in this regard, such that when the cylinders of the cylinder unit move, their ends move essentially symmetrically with respect to a plane spanned by the longitudinal axis L and the axis of rotation of the rotary shaft 19. When extended, the free ends of the cylinders thus move uniformly away from the plane, and when retracted, they move uniformly towards the plane.The cylinder unit is connected via the coupling unit to a working medium, such as compressed air, vacuum, and / or electrical power, which controls the extension and retraction of the cylinders of the cylinder unit in the manner described above. The retracted and extended positions of the cylinder unit can be limited by stops, and the positions can be determined using suitable decoders. The cylinders can, for example, be mechanically preloaded into a retracted position via a spring, so that the working medium must move the cylinders against the preload. In the absence of the working medium, the cylinders automatically return to the retracted position, which corresponds to a gripping position, as explained in more detail below.

[0038] The actuating unit 40 and the coupling unit 25 may be covered by a common housing 45, as shown in Figures 2 to 4.

[0039] At the free ends of each cylinder of the cylinder unit 44, one of the gripping jaws 42 is attached in such a way that it extends essentially parallel to the longitudinal axis L away from the coupling unit 25. The gripping jaws are rigidly attached to the cylinders and move with them. When the cylinders are extended, the gripping jaws move apart symmetrically to the aforementioned plane, and when retracted, they move symmetrically towards each other into a gripping position, as will be recognized by one skilled in the art. The gripping jaws 42 are essentially symmetrical with respect to a plane spanned by the longitudinal axis L and the axis of rotation of the rotary shaft 19. The gripping jaws are contoured on the sides facing one another in order to receive and grip a wafer cassette therebetween. The contour of the gripping jaws 42 is adapted to the contour of the wafer cassettes to be gripped.In particular, the contour can be selected in such a way that it can accommodate and grip two different wafer cassettes (type / size) with the same cylinder stroke.

[0040] In the illustrated embodiment, this is achieved in that the gripping jaws 42 each have two vertically offset support surfaces 48, 49, as well as a contact surface 50. The support surfaces 48, 49 extend essentially horizontally and parallel to the direction of movement of the cylinders of the cylinder unit 44. The contact surface 50 extends essentially vertically, or perpendicular to the support surfaces. The support surface 48 is arranged above the contact surface 50 and extends directly adjacent to it to the rear. The support surface 49 is arranged below the contact surface 50 and extends adjacent to it to the front.

[0041] The wafer cassettes to be picked up have corresponding contours in order to cooperate with the wafer grippers and the respective support and contact surfaces, as will be explained in more detail with reference to Figures 5 and 6. These each show the engagement of a gripping jaw 42 with a wafer cassette 60, 60', wherein wafer cassettes of different types and sizes are shown in the figures. The wafer cassettes 60, 60' each have a recessed area 61, 61' at their lower ends, extending in the longitudinal direction (perpendicular to a loading / unloading opening) of the wafer cassette, such that a laterally facing edge 64, 64' and a downwardly facing edge 65, 65' are formed. The recessed region 61, 61' is formed with respect to a side wall of the wafer cassette 60, 60', which essentially defines the width of the wafer cassette 60, 60'.On the inner sides of the side walls, above the recessed areas 61, 61', supports for the wafers to be accommodated are arranged. The distance between the side walls can thus also limit the size of the wafers to be accommodated.

[0042] The outer distance between the side walls of the wafer cassette 60 (Fig. 5) differs from the outer distance between the side walls of the wafer cassette 60' (Fig. 6). In particular, the outer distance between the side walls of the wafer cassette 60 (Fig. 5) is smaller than the outer distance between the side walls of the wafer cassette 60' (Fig. 6). However, the outer distance between the laterally facing edges 64' of the wafer cassette 60' is substantially equal to the outer distance between the side walls of the wafer cassette 60. Thus, the contact surface 50 of the wafer grippers 42 can engage either the side walls of the wafer cassette 60 or the laterally facing edges 64' with the same stroke, as shown in Figs. 5 and 6.

[0043] In the wafer cassette 60 according to Fig. 5, the lower support surface 49 of the wafer gripper, which extends forward with respect to the support surface 50, can move into contact with the downward-facing edge 65 of the recessed area 61 when the gripper is lifted, thus securely picking up and holding the wafer cassette. In the wafer cassette 60' according to Fig. 6, on the other hand, the upper support surface 48 of the wafer gripper, which extends rearward with respect to the support surface 50, can move into contact with the downward-facing edge 65' of the recessed area 61' when the gripper is lifted, thus securely picking up and holding the wafer cassette. The downward-facing edge 65, 65' is particularly suitable for contact with the respective support surface 48, 49, since this edge is generally freely accessible (does not serve as a standing surface) and is well-defined.

[0044] The gripper jaws are therefore contoured so that they can accommodate different wafer cassettes (which are contoured accordingly) with a constant stroke. In addition to the configuration shown, which is based on wafer cassettes found in the field, other configurations are of course also possible.

[0045] An alternative embodiment of the end effector 13 is described with reference to Figures 7 and 8, wherein the same reference numerals are used as before to describe identical or similar elements. The end effector 13 again has 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 and the first gripping unit 27 are essentially identical to the first embodiment and will therefore not be described again.

[0046] The second gripping unit 28 again has an actuating unit 40 and two gripping jaws 42 connected to the actuating unit 40. The actuating unit 40 can have essentially the same structure as in the first embodiment.

[0047] The main difference to the first embodiment lies in the gripping jaws 42. While the gripping jaws 42 of the first embodiment have a substantially horizontal orientation with, among other things, horizontal support surfaces, the

[0048] Gripping jaws 42 according to Figures 7, 8 have a substantially vertical orientation.

[0049] In particular, the gripping jaws 42 of Figures 7, 8 are configured to grip a vertically extending flange of a 60" wafer cassette. Such a flange extends, for example, over the height of the front side (a loading / unloading opening on the side) of the 60" wafer cassette and extends outwards with respect to the loading / unloading opening. Such flanges are already provided in some cases for wafer cassettes in the field. The 60" wafer cassette can be gripped by appropriate engagement with the flanges. For additional support, horizontal supports (not shown) can also be provided on the gripping jaws, which can engage with the underside of the 60" wafer cassette or with a downward-facing contact surface analogous to the embodiment according to Figures 5 and 6.

[0050] The invention has been explained in more detail above with reference to the embodiment illustrated in the figures, without being limited to the precise embodiments. A person skilled in the art will recognize a wide variety of embodiments in light of the teachings of the invention, particularly with regard to the precise designs of the first and second gripping units of the end effector.

Claims

Patent claims 1. An end effector comprising: a first gripping unit configured to pick up and hold individual wafers; a second gripping unit configured to pick up and hold a wafer cassette, wherein the first and second gripping units are connected to one another such that they can be attached to a common robot arm and are arranged at an angle to one another such that they do not interfere with one another during operation.

2. End effector according to claim 1, wherein the first and second gripping units are arranged at an angle of approximately 180° to each other.

3. End effector according to claim 1 or 2, wherein the first and second gripping units are connected to one another via a coupling unit, wherein the coupling unit is connectable to the common robot arm in such a way that the coupling unit connects at least one connection for a working medium, preferably the same connection, for the actuation of the respective gripping units to these.

4. End effector according to one of the preceding claims, further comprising a rotating unit via which the end effector can be mounted on the robot arm so as to be rotatable back and forth between at least two positions, wherein the position of the end effector determines the readiness for use of the first or the second gripping unit.

5. End effector according to one of the preceding claims, wherein the first gripping unit is designed as a vacuum, Bernoulli gripper or edge gripper.

6. End effector according to one of the preceding claims, wherein the second gripping unit has movable jaws, the contour of the jaws being designed is that they can accommodate at least two different cash register sizes or types with the same travel path. The end effector according to claim 6, wherein the movable jaws are adjustable via a cylinder unit, the jaws being mechanically preloaded into a gripping position. A robot comprising a drive train with at least one robot arm that carries an end effector according to one of the preceding claims at its free end.

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