Patent Grant
7688017
The present invention relates to semiconductor device manufacturing, and more particularly to a multi-axis motor assembly for use with a wafer handler.
In the manufacture of semiconductor devices, such as integrated circuits (ICs), dynamic random access memories (DRAMs), etc., large thin wafers (typically of silicon) from which the semiconductor devices are fabricated must frequently be transferred from one processing chamber to another. This transfer of wafers must be carried out in a clean environment and often at sub-atmospheric pressures. To this end various mechanical arrangements have been devised for transferring wafers to and from processing chambers in a piece of equipment or from one piece of equipment to another.
It is the usual practice to load wafers into a cassette so that a number of wafers can be carried under clean-room conditions safely and efficiently from one place to another. A cassette loaded with wafers may then be inserted into an input/output (I/O) chamber (“load lock” chamber) where a desired gas pressure and atmosphere can be established. The wafers are fed one-by-one to or from their respective cassettes into or out of the I/O chamber.
It is desirable from the standpoint of efficiency in handling of the wafers that the I/O chamber be located in close proximity to a number of processing chambers to permit more than one wafer to be processed nearby and at the same time. To this end two or more chambers are arranged at locations on the periphery of a transfer chamber which is hermetically sealable and which communicates with both the I/O chamber and the processing chambers. Located within the transfer chamber is an automatically controlled wafer handling mechanism, or robot, which takes wafers supplied from the I/O chamber and then transfers each wafer into a selected processing chamber. After processing in one chamber a wafer is withdrawn from the chamber by the robot and inserted into another processing chamber, or returned to the I/O chamber and ultimately a respective cassette.
Semiconductor wafers are by their nature fragile and easily chipped or scratched. Therefore they are handled with great care to prevent damage. The robot mechanism which handles a wafer holds it securely, yet without scratching a surface or chipping an edge of the brittle wafers. The robot moves the wafer smoothly without vibration or sudden stops or jerks. Vibration of the robot can cause abrasion between a robot blade holding a wafer and a surface of the wafer. The “dust” or abraded particles of the wafer caused by such vibration can in turn cause surface contamination of other wafers. As a result, the design of a robot requires careful measures to insure that the movable parts of the robot operate smoothly without lost motion or play, with the requisite gentleness in holding a wafer, yet be able to move the wafer quickly and accurately between locations.
Because of space constraints under and/or within a transfer chamber, it is desirable to reduce the height of the motor assembly employed to drive a robot. It is also desirable to provide a robot able to independently handle multiple wafers so as to increase the through-put of a wafer-processing apparatus.
In a first aspect of the invention, a first multi-axis vacuum motor assembly is provided. The first multi-axis vacuum motor assembly includes (1) a first rotor; (2) a first stator adapted to magnetically couple with the first rotor across a vacuum barrier so as to control rotation of a first axis of a robot arm within a vacuum chamber; (3) a second rotor below the first rotor; (4) a second stator below the first stator and adapted to magnetically couple with the second rotor across the vacuum barrier so as to control rotation of a second axis of the robot arm within the vacuum chamber; (5) a first feedback device located on an atmospheric side of the vacuum barrier and adapted to monitor rotation of the first axis of the robot arm via passive magnetic coupling across the vacuum barrier; and (6) a second feedback device located on the atmospheric side of the vacuum barrier and adapted to monitor rotation of the second axis of the robot arm via passive magnetic coupling across the vacuum barrier.
In a second aspect of the invention, a second multi-axis vacuum motor assembly is provided. The second multi-axis vacuum motor assembly includes (1) a first rotor; (2) a first stator adapted to commutate so as to rotate the first rotor across a vacuum barrier and control rotation of a first axis of a robot arm within a vacuum chamber; (3) a second rotor below the first rotor; (4) a second stator below the first stator and adapted to commutate so as to rotate the second rotor across the vacuum barrier and control rotation of a second axis of the robot arm within the vacuum chamber; (5) a first feedback device adapted to monitor rotation of the first axis of the robot arm; and (6) a second feedback device adapted to monitor rotation of the second axis of the robot arm.
Numerous other aspects are provided, including methods of operating a robot arm using the first and second multi-axis vacuum motor assemblies. Other features and aspects of the present invention will become more fully apparent from the following detailed description, the appended claims and the accompanying drawings.
Disclosed is a multi-axis motor assembly for use in a transfer or other chamber. The improved design allows feedback devices and/or motor elements to be nested so as to reduce stack height below the transfer chamber. Additionally, sensing functions need not be transmitted across a vacuum barrier.
The first multi-axis vacuum motor assembly 100 of
The first stator 102 may be affixed to the vacuum barrier 106 on the atmospheric side. In one embodiment, the first stator 102 is stationary and may be affixed to the vacuum barrier 106 such that there is no air gap between the first stator 102 and the vacuum barrier 106, allowing for maximum magnetic efficiency. Other configurations may be employed.
The first rotor-stator pair 102, 104 may, for example, comprise a portion of a conventional brushless DC motor or any suitable motor configuration.
The first rotor 104 is coupled to a first axis of a robot arm 110 via a first hub 112 (e.g., of a frog-leg or other robot). Also coupled to the first hub 112 is a first passive rotary magnetic coupling 114 (M1). The first rotary magnetic coupling 114 is magnetically coupled to a second passive rotary magnetic coupling 116 (Mag 1) across the vacuum barrier 106. The second rotary magnetic coupling 116 is coupled to a first feedback device 118 (Encoder 1). As this feedback device is outside of the vacuum chamber 108, at atmosphere, there is little restriction as to the device technology available for use as the feedback device 118. For example, the feedback device 118 may be a resolver, an optical encoder, a magnetic encoder, or any other appropriate device (e.g., useful for positioning and/or commutating a vacuum robot).
The first feedback device 118 is coupled to and may communicate positional information about the first robot arm 110 to a controller 119 that is adapted to control operation of a robot (not separately shown) that is driven by the multi-axis vacuum motor assembly 100. For example, the first feedback device 118 may be hardwired to or communicate wirelessly with the controller 119.
Nested with the motor elements and feedback device described above is a second feedback device, motor stator drive, and magnetic coupling system. As shown in
The second stator 120 may be affixed to the vacuum barrier 106 on the atmospheric side. In one embodiment, the second stator 120 is stationary and may be affixed to the vacuum barrier 106 such that there is no air gap between the second stator 120 and the vacuum barrier 106, allowing for maximum magnetic efficiency. Other configurations may be employed.
The second rotor-stator pair 120, 122 may, for example, comprise a portion of a conventional brushless DC motor or any suitable motor configuration.
The second rotor 122 may be coupled to a second axis of a robot arm 124 via a second hub 126 (e.g., of a frog-leg or other robot). Also coupled to the second hub 126 may be a third passive rotary magnetic coupling 128 (M2). The third rotary magnetic coupling 128 is magnetically coupled to a fourth passive rotary magnetic coupling 130 (Mag 2) across the vacuum barrier 106. The third rotary magnetic coupling 128 is coupled to a second feedback device 132 (Encoder 2). As with the first feedback device 118, the second feedback device 132 may be a resolver, an optical encoder, a magnetic encoder, or any other appropriate feedback device.
The second feedback device 132 is coupled to and may communicate positional information about the second robot arm 124 to the controller 119 that is adapted to control operation of a robot (not separately shown) that is driven by the multi-axis vacuum motor assembly 100. For example, the second feedback device 132 may be hardwired to or communicate wirelessly with the controller 119. In a hardwired embodiment, the first and/or second feedback devices 118, 132 may include a hollow bore that allows wires to pass to the controller 119 or any other suitable location.
Note that bearings may be provided between components that move and/or rotate relative to one another. For example, as shown in
As further shown in
In the embodiment shown, the first rotary shaft 202 and second rotary shaft 204 are coaxial (although other configurations may be used). That is, in this exemplary diagram, the first rotary shaft 202 is contained within the second rotary shaft 204. This design allows for a similar compactness to the first multi-axis motor assembly 100 of
The multi-axis vacuum motor assemblies of the present invention provide for a more compact design that may reduce space required under or within a transfer chamber (vacuum chamber 108). In particular, the space required under a transfer chamber is reduced by the vertical compactness of the present invention, as mentioned above. Vertical compactness is synonymous with reduced height, and the height of an assembly correlates to the height of its components. Vertical compactness does not require horizontal compactness, however, so an assembly, and by extension, at least a portion of its components, may have a reduced height, but a non-reduced width. For instance, as depicted in
Note that any number of coaxial axes may be employed (e.g., such as four axes separated by a spool piece or the like). For example, the multi-axis vacuum motor assembly 100 and/or 200 may be used with the multi-wafer handling robots disclosed in U.S. Pat. Nos. 6,379,095 and 6,582,175 which are hereby incorporated by reference herein in their entirety (e.g., multi-wafer handling robots that may transfer two, four or more substrates at a time).
Further, the rotor-stator positions shown in
Through use of the multi-axis vacuum motor assembly 100 and/or 200, a robot such as a frog-leg robot, a SCARA robot, etc., may be controlled. For example, by employing the first stator and the second stator to rotate the first axis and second axis of a robot arm, the robot arm may be extended, retracted and/or rotated. More specifically, commutating the first stator and the second stator causes the first axis and second axis of the robot arm to rotate so as to extend, retract and/or rotate the robot arm.
Accordingly, while the present invention has been disclosed in connection with exemplary embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claims.
The present application claims priority from U.S. Provisional Patent Application Ser. No. 60/652,145, filed Feb. 12, 2005, which is hereby incorporated by reference herein in its entirety.
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