WO1997010079A1

WO1997010079A1 - Concentric dual elbow

Info

Publication number: WO1997010079A1
Application number: PCT/US1996/014677
Authority: WO
Inventors: Matthew J. Van Doren
Original assignee: Silicon Valley Group, Inc.
Priority date: 1995-09-13
Filing date: 1996-09-13
Publication date: 1997-03-20
Also published as: AU7361096A

Abstract

A workpiece handling arrangement comprises a first workpiece handling means (20) rotatably mounted on a first shaft (44) and a second workpiece handling means (20) rotatably mounted on a second shaft (46). The first shaft (44) is preferably hollow and defines an outer shaft, the workpiece handling means (20) are capable of independent relative movement and are connected to separate motors. The workpiece handling means can include grippers (14) for gripping workpieces such as semiconductor wafers (12). The first shaft (44) is preferably hollow and defines an outer shaft, the second shaft (46) being arranged concentrically within the outer shaft so that the outer shaft rotatably supports the inner shaft. Typically, the inner shaft is also a hollow shaft.

Description

CONCENTRIC DUAL ELBOW

Technical Field

This invention relates to a robotic arm arrangement.

Background Art

Modem production plants typically make use of mechanical help in the form of robots to convey workpieces from one station to the next. In the semiconductor chip manufacturing field, accurate conveyance of semiconductor wafers is achieved by means of grippers that support a wafer and transfer it from one location to another, A wide range of robotic arms has been developed to perform various tasks. For instance, a robot specifically for use in wafer handling is illustrated in Patent No. 5,340,261 to Oosawa.

With prior art devices, the production rate is dependent directly on the speed of movement of a robotic arm in transferring workpieces from one work station to the next. To increase production, the speed of movement of the robotic arm is increased to the extent that it causes no degradations in the work product. For instance, in the semiconductor field, rapid movement of a wafer causes turbulent air flow, thereby stirring up particles within the robotic machine and compromising the clean environment required for wafer production. Patent No. 5,007,784 instead proposes the use of a pair of grippers at opposite ends of an arm that is rotatable about a central point.

Disclosure of the Invention

It is an object of the invention to provide a workpiece handling robot capable of increased transfer rates without increasing the speed of movement of the robot. It is a further object of the invention to provide an arrangement in which two workpiece handlers are mounted on a single robotic structure and are capable of independent movement.

It is yet a further object of the invention to provide a compact dual workpiece handler in which each handler is driven independently and in which the handlers are secured to independent concentric axes.

According to the invention, there is provided a workpiece handling arrangement comprising a first workpiece handling means rotatably mounted on a first, tubular, shaft; a second workpiece handling means rotatably mounted on a second, concentric, shaft extending co-axially within the first shaft; a first motor connected to the first shaft for rotating the first shaft; and a second motor connected to the second shaft for rotating the second shaft.

Further, according to the invention, there is provided a wafer handling arrangement comprising a first wafer gripper rotatably mounted on a first, tubular, shaft; a second wafer gripper rotatably mounted on a second, concentric, shaft extending co-axially within the first shaft; a first motor connected to the first shaft for rotating the first shaft; and a second motor connected to the second shaft for rotating the second shaft. Still further according to the invention, there is provided a robot comprising a first workpiece handling means rotatably mounted on a first shaft; a second workpiece handling means rotatably mounted on a second shaft aligned parallel to the first shaft; a first motor connected to the first shaft for rotating the first shaft; and a second motor connected to the second shaft for rotating the second shaft, wherein the first and second shafts are mounted on a support base having an axis of rotation parallel to the shaft axes, the base being movable rotatably about the axis of rotation, and linearly along the axis of rotation.

Brief Description of the Drawings

Fig. 1 is an isometric view of a typical semiconductor chip manufacturing process tool;

Fig. 2 is an isometric view of a robot having a dual gripper arrangement in accordance with the invention;

Fig. 3 is an isometric view of the robot of Fig. 2 showing the robot in a collapsed state and from the opposite side; Fig. 4 is a sectional side view of the dual gripper arrangement;

Fig. 5 is a plan view of the dual gripper arrangement with the upper cap and gripper housings removed;

Fig. 6 is a side view of the dual gripper arrangement of Fig. 5; and Fig. 7 is an end view of the dual gripper arrangement of Fig. 5.

Best Mode for Carrying Out the Invention

For ease of description the invention will be described specifically with respect to a semiconductor wafer handling process. However, the invention is applicable to any production process in which mechanical robots are to be used to transfer workpieces from one work station to another.

Fig. 1 illustrates part of a typical semiconductor production facility. Robots 10 transfer semiconductor wafers 12 from one work station to another. The wafers 12 are handled by means of grippers 14 which hold the wafers as they are transported to the next work station. Vertical movement of the grippers 14 is achieved by means of a tubular arrangement 16 capable of producing vertical translational movement. Horizontal translation is achieved by propelling the robot 10 along horizontally extending rails 18. In addition, the arm 20 is rotatable either by rotation relative to the cylindrical arrangement 16 or by the rotation of the entire cylindrical arrangement 16. The wafer grippers 14 include housings 22 which are rotatably mounted on the arm 20, as discussed in greater detail below.

Figs. 2 and 3 illustrate the robot 10. The arm 20 is mounted on the upper end of a tube 24 and supports the housings 22 of the wafer grippers 14. The housings 22 are rotatably mounted on the arm 20, the arm 20 constituting of a housing for a drive mechanism that provides rotational movement of the housings 22. This is discussed in greater detail below.

Fig. 4 shows a sectional side view of the arm 20, the housings 22 and the griping elements 28. The arm 20 is secured to the cylinder 24 (Fig. 2) by means of bolts 30. As can be seen in Fig. 4, the arm 20 forms a housing that houses a first pulley 32 and a second pulley 34. The first pulley 32 is connected to a shaft 36 of a first electric motor 38. Similarly, the pulley 34 is secured to a shaft 40 of a second electric motor 42. The staggered arrangement of the motors 38, 42 is illustrated in Fig. 7 which shows the workpiece handling arrangement from the rear end with the housing 22 removed. The pulleys 32, 34 are spaced vertically from each other and, as shown in the plan view of Fig. 5, are also spaced laterally from each other.

The housings 22 are rotatably mounted on the arm 20 by means of concentric shafts 44, 46. The inner shaft 46 extends within the hollow tubular outer shaft 44. Pulleys 48, 52 are secured to the shafts 44, 46,respectively. This allows the pulley 32 of the motor 38 to be connected to the pulley 48 by means of a belt 54. Similarly, the pulley 34 of the motor 42, is connected to the pulley 52 by means of a belt 56. This is clearly illustrated in Fig. 6, which shows the arrangement from the side with the housings 22 removed. As shown in Fig. 4, the upper gripper housing 60 is secured to the upper protrusion of the shaft 46 by means of bolts 62 and the pulley 52 is secured to the lower protrusion. The lower gripper housing 64 is, in turn, bolted to the shaft 44 by means of bolts 66.

The motors 38, 42 are capable of independent motion, allowing the shafts 44, 46 to be independently rotated. The lower motor 42 manipulates the inner shaft 46, connected to the upper gripper housing 60. The upper motor 38, in turn, manipulates the outer shaft 44, which is connected to the lower gripper housing 64. In order to lift a wafer,the grippers 28 are maneuvered around the wafer and then closed against its peripheral edge. Electric motors housed in the housings 22 perform the opening and closing movements of the grippers 28. In the preferred embodiment the inner shaft 46 is a hollow tube, as illustrated in Figs. 4 to 7. This allows electrical conductors for the motors housed in the housings 22 to be passed centrally along the shaft 46. In this manner power can be supplied to the gripper motors without sacrificing the compactness of the concentric shaft arrangement.

In the arrangement illustrated in Fig. 4 a protective plate 70 is provided to protect the lower wafer 72 from the upper wafer 74. The plate 70 is secured to a support 76 by means of a bracket 78. The plate 70, support 76, and bracket 78 thus define a protective housing having open sides. In the embodiment illustrated in Fig. 4, the support 76 is bolted to the cylindrical portion 80 of the arm 20 to serve as a cover for the cylindrical portion 80. The use of independently driven wafer grippers connected to a single robotic arrangement provides much greater versatility and makes for a compact wafer handling arrangement.

It will be appreciated that the workpiece handling means need not be limited to wafer grippers but extends equally to other workpiece handling means and to the handling of a wide range of workpieces.

Claims

WE CLAIM:

1. A workpiece handling arrangement comprising a first workpiece handling means rotatably mounted on a first, tubular, shaft; a second workpiece handling means rotatably mounted on a second, concentric, shaft extending co-axially within the first shaft; a first motor connected to the first shaft for rotating the first shaft; and a second motor connected to the second shaft for rotating the second shaft.

2. A workpiece handling arrangement of Claim 1 , wherein each workpiece handling means includes a gripper for gripping a workpiece.

3. A workpiece handling arrangement of Claim 2, wherein the workpiece is a semiconductor wafer.

4. A workpiece handling arrangement of Claim 1 , wherein the second shaft protrudes from both ends of the first shaft.

5. A workpiece handling arrangement of Claim 1 , wherein the second shaft is hollow.

6. A workpiece handling arrangement of Claim 1 , wherein each shaft has a first end connected to its motor by a belt-and-pulley arrangement, and a second end connected to its workpiece handling means.

7. A wafer handling arrangement comprising a first wafer gripper rotatably mounted on a first, tubular, shaft; a second wafer gripper rotatably mounted on a second, concentric, shaft extending co-axially within the first shaft; a first motor connected to the first shaft for rotating the first shaft; and a second motor connected to the second shaft for rotating the second shaft.

8. A robot comprising a first workpiece handling means rotatably mounted on a first shaft; a second workpiece handling means rotatably mounted on a second shaft aligned parallel to the first shaft; a first motor connected to the first shaft for rotating the first shaft; and a second motor connected to the second shaft for rotating the second shaft, wherein the first and second shafts are mounted on a support base having an axis of rotation parallel to the shaft axes, the base being movable rotatably about the axis of rotation, and linearly along the axis of rotation.