JP2003188233A - Joint-arm type transfer unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high reliability transfer unit. <P>SOLUTION: A joint-arm transfer unit 10, that adopts a rhomboid linkage structure formed by two pairs of front arms (12, 13, 14, 15) are disposed separated from each other, which are jointed so as to be rotatable at elbow portions and wrist portions. Each wrist portion supports holding means (25, 25'), and the elbow portions are moved by a pair of upper arms (17, 18) along a semi-circular path that is in mirror reflection symmetry. When each of the upper arms (17, 18) rotates about its adjacent shoulder joint portion, the upper arms (17, 18) go under either one of the front arms (12, 13, 14, 15) and overlap with each other. In this unit, one holding means (25, 25') always moves quickly in between extended position and stop position, and the other holding means (25, 25') moves slowly in a minute distance in between the stop position and retracted position. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Background Art FIELD OF THE INVENTION The present invention relates generally to material transfer devices. The material to be transferred is not particularly limited, but for example,
Semiconductor wafers such as silicon and gallium arsenide, semiconductor packaging substrates such as high density interconnects, image forming plates used in semiconductor manufacturing processes such as masks and reticles, and active matrix LCD substrates. Large area display panels such as.

[0002]

2. Description of the Related Art 2. 2. Description of the Related Art In the manufacture of semiconductor devices, when a fragile silicon wafer or the like is transferred between a plurality of work stations, that is, working positions, a particular problem occurs in the handling thereof.
Silicon wafers are very fragile and have a highly polished surface. The wafer is slippery when moved abruptly. Then, due to such sliding, the silicon wafers are worn or their edges are damaged in the case of collision. Many conventional techniques described below have been disclosed as a silicon wafer transfer device. U.S. Pat. No. 3,823,836 discloses an apparatus including a feed transfer table having a plurality of shelves for holding silicon wafers and a drawing apparatus having a vacuum chuck. The vacuum chuck is attached to an elevator that moves the chuck up and down. A horizontal transfer arm connected to the vacuum chuck transfers the silicon wafer from the transfer table for supply to a desired workstation. U.S. Pat. No. 3,7
No. 30,595 discloses a wafer transfer handling apparatus having an indexable transfer table for loading and unloading wafers to and from a work station. Wafers are loaded and unloaded from a wafer transfer table on an air slide by a wafer ejection receiving arm having a plurality of directional air jets.
The wafer ejection receiving arm controls the movement of the wafer between the transfer table and the air slide, thereby transferring the wafer to and from the work station. US Patent No. 4,
062, 463, 3, 874, 525 and 4,
No. 208,159 discloses a wafer transfer device that utilizes pneumatic elements or gripping devices to handle the wafers. U.S. Pat. Nos. 4,666,366 and 4,909,7.
No. 01 discloses a wafer transfer handling apparatus having an articulating arm assembly that expands or contracts in a "frog-like" motion to transfer an object such as a wafer between multiple positions. The two articulated arms expand and contract in a "frog-like" or "frog-leg kick-like" motion when one arm is driven by a motor. Operatively connected as described above. The loading / unloading table is connected to the arm, and the transferred object is mounted on the mounting table.

[0003]

However, since the articulated arm assembly of the above-mentioned transfer device is provided with only a single mounting table, there is a limit in processing capacity. Under such circumstances, there is a demand for a transfer device having a simple structure and high reliability, which does not damage the transferred object and can improve the processing capacity as compared with the conventional device.

[0004]

SUMMARY OF THE INVENTION The present invention provides an article, such as a silicon wafer, camera lens, or crystal oscillator, between a plurality of positions arranged on various axially and radially extending surfaces. The present invention is characterized by providing a device having a simple structure for transferring and having high reliability.
The apparatus of the present invention comprises one support, two sets of front arms articulated with a pair of upper arms (or drive arms), and a mounting table (or end ifer) connected to each set of front arms. An end effector, or other suitable holding device), and a motor that drives one of the upper arms. A pair of upper arms and two pairs of front arms expand and contract in a "frog-like" or "frog-leg kick-like" motion when the upper arms are driven by a motor. So that they are operably linked.
If the end effector in the extended position is empty without an article and the end effector in the retracted position has an article, the end effector on the non-empty side should be given no large acceleration and velocity (otherwise , The substrate that is the article moves with respect to the end effector), and the empty end effector is pulled back with a large acceleration and velocity. As a result, the time interval from the delivery of the first substrate to the delivery of the next substrate can be shortened. The articulated arm assembly is preferably coupled to the base via a rotary motor so that the entire articulated arm assembly can rotate in a radial plane.
Similar to prior art devices with a single platform, the articulated arm assembly is rotated when each end effector is not in the extended position. However, unlike the prior art, in the device of the present invention, if one end effector is fully retracted, the other end effector is always in the fully extended position. Thus, in the present invention, the support rotates when both end effectors are in the intermediate "stop" position. The provision of such a "temporary stop" position is an important feature of the present invention. Also, in one embodiment, the articulated arm assembly preferably moves the mounting table assembly axially,
It is connected to the base via a plurality of flexible bodies or levers that respond to force. In another embodiment, the arm assembly is attached by means other than the flexible body so that the mounting table assembly can be moved in the axial direction over a wider range than that obtained by the flexible body. The assembly is adaptable to various environments, such as, for example, a vacuum chamber or other conditioned atmosphere of the atmosphere. The assembly may also be mounted for movement within a vacuum chamber by sealing a vacuum seal between the assembly and its support.

DETAILED DESCRIPTION OF THE INVENTION The device of the present invention has a first shoulder pivot 50 and a second shoulder pivot 51. The centerline of the device is equidistant from the first and second shoulder pivots. First
The upper arm 18 includes first elbow joint means rotatably mounted on the first shoulder pivot 50 and including at least one first elbow pivot that is spaced from the first shoulder pivot by the length of the upper arm. . The second upper arm 17 is rotatably provided on the second shoulder pivot 51 and includes at least one second elbow pivot that is separated from the second shoulder pivot by the length of the upper arm. Have. The primary first front arm 12 has a primary first wrist swivel shaft provided on the first elbow swivel shaft and spaced from the first elbow swivel shaft by the length of the primary front arm. Primary side second front arm 1
3 has a primary side second wrist pivot axis provided on the second elbow pivot axis and separated from the second elbow pivot axis by the length of the primary side front arm. The primary side holding means 25 is attached to the primary side wrist pivot shaft. A primary side coupling mechanism provided between both wrist side pivot shafts on the primary side prevents rotation of the primary side holding means and limits its movement to movement along the center line. The sum of the length of the primary front arm plus the separation between any one of the primary wrist pivots and the centerline is less than the maximum separation between any elbow joint and the centerline. Is also big. Secondary-side first forearm 14
Has a secondary first wrist pivot that is provided on the first elbow pivot and spaced from the first elbow pivot by the length of the secondary forearm. Secondary-side second front arm 15
Has a secondary side second wrist pivot axis provided on the second elbow pivot axis and separated from the second elbow pivot axis by the length of the secondary side forearm. The secondary side holding means 25 'is attached to both wrist rotation shafts. The secondary side coupling mechanism provided between both secondary wrist rotation shafts prevents rotation of the secondary side holding means and limits its movement to movement along the center line. The sum of the length of the secondary front arm plus the separation distance between any one of the secondary wrist pivots and the centerline is
Greater than the maximum separation between any elbow joint and the centerline. Further, means for driving the first upper arm to be rotatable in an angular range of more than 120 ° and 180 ° or less is provided, and by this means, the primary side holding means is moved between the primary side extended position and the primary side retracted position. At the same time, the secondary side holding means is moved between the retracted position on the secondary side and the extended position on the secondary side.

The holding means is used to hold a semiconductor wafer or the like. This holding means moves along the center line. The speed of the holding means is also a function of the speed component of the elbow pivot in the direction parallel to the center line. Therefore, if the angular velocity of the upper arms is constant, the velocity of the support will be maximized when the upper arms spread apart from each other.

Here, the size of the length of the front arm plus the separation distance between any one of the wrist pivot axes and the center line is defined as "A", and one of the lengths of the upper arms is set. If the size including the distance between the shoulder pivot and the center line is “B”, the following relationship is established. If A
If B is less than B, the system is inoperable before the upper arms expand into each other. If A = B and the distance from the central axis of the shoulder pivot is equal to the distance from the central axis of the wrist pivot, then each forearm is moveable to overlap each other. If A =
At B, if the distance from the centerline of the wrist pivot axis is greater than the distance from the centerline of the shoulder pivot axis, then the wrist pivot axis may “go over” the shoulder pivot axis. If A = B (or A is greater than B),
If the distance from the center axis of the wrist rotation axis is smaller than the distance from the center axis of the shoulder rotation axis, the wrist rotation axis does not overlap with the shoulder rotation axis. The device is symmetrical with respect to the centerline.

Normally, the difference between the length of the front arm and the length of the upper arm is very small, but under this condition, the holding means is
The distance between the fully extended position and the stop position is approximately twice the arm length, while the distance between the stop position and the fully retracted position is slightly longer than the above difference. Do not move.

The capability of the device of the present invention is that, due to the characteristics of the drive structure as follows, a single drive mechanism can impart different velocities along a common centerline to two end effectors. is there. When the elements of the drive mechanism are simplified, each end effector is driven by a substantially diamond shaped drive structure. In the rhombic structure, one vertex is selected as the pivot and around that pivot,
Both sides adjacent to the apex rotate. Now, considering the movement of this rhombus structure, when the sides on both sides adjacent to the apex rotate, the apex angle becomes 180 °, the area of the rhombus disappears, and the pair of adjacent side portions adjoin each other. Overlapping a pair of sides. Then, when further rotated, the two pairs of sides show one of the following two movements. That is,
Rotate to open the diamond or rotate with the two pairs of sides still overlapping to hold the closed diamond. The former moves so that the apex on the opposite side of the apex which is the turning axis moves away from the apex which is the turning axis at high speed. The latter does not impose movement speed on any of these vertices.

The structure of the device of the present invention utilizes the above properties to provide different motions to the two drive structures. That is, one drive structure is actuated to open the rhombus, giving its end effector a large velocity, while the other drive structure is actuated to hold the closed rhombus and ignored by the end effector. Give only as fast as you can.

The structure of the device according to the invention comprises a drive mechanism having a pair of drive arms which are connected at one end and which rotate in opposite directions, the free ends of which when the drive arms rotate about the ends. It moves along a semi-circular orbit of mirror symmetry (with respect to the centerline). Two pairs of front arms spaced apart from each other are coupled between the free ends of the drive arms, and each pair of front arms carries a retaining means (such as an end effector) at the connection between the front arms. To do. The link structure formed by the two pairs of forearms is usually a rhomboid rather than a pure rhombus. In particular, each pair of front arms forms with the drive arm a rhomboidal drive structure. From the state in which the drive arms are located at one moving end (in this state, the drive arms are substantially adjacent to each other, and one holding means is projected from the connecting end portion of the drive arms) to the “temporarily stopped” position ( (In this state, the drive arms are expanded linearly with respect to each other.)
When moving to, the protruding retaining means move rapidly towards the stop position once and the area formed by the rhomboid link structure expands from a narrow strip along the centerline to a square, then It contracts into a narrow strip that is orthogonal to the centerline. The area formed by the rhomboid structure with the drive arm and the front arm with the retracted holding means exhibits a shape change substantially similar to the link structure.
On the other hand, the area formed by the front arm with the drive arm and the holding means on the non-retracted side is small, so that the holding means on the non-retracted side moves only slightly.

When the drive arm crosses the "stop" position,
When it goes to the opposite moving end (in this state, the driving arms are substantially adjacent to each other and the holding means on the other side is projected from the connecting end portion of the driving arm), the above-mentioned projecting once, After that, the holding means pulled back moves only slightly, and the area formed by the rhomboid link structure is expanded from a narrow strip orthogonal to the center line to a square, and then to a narrow strip along the center line. Be contracted. The rhomboidal area formed by the drive arm and the front arm with the newly overhanging retaining means provides a shape change substantially similar to the link structure. On the other hand, the area formed by the drive arm and the forearm with the holding means retracted changes only slightly.

As described above, the feature of the present invention is that the characteristics of the rhombus structure described above are applied to the rhomboid structure so that different speeds are imparted to the two end effectors by a single drive mechanism. is there.

That is, according to the present invention, it is possible to accelerate and decelerate the retracted arm very rapidly and safely without giving a large acceleration or deceleration to the second end effector. Therefore, when the end effector in the extended position is emptied after the wafer is handed over, the end effector in the retracted position can provide an advantage in terms of operating capability when it remains occupied by the wafer. . In many applications, the wafer is held on the end effector only by surface friction, which can cause the wafer to slip on the end effector due to rapid acceleration or deceleration of the end effector holding the wafer. Is not preferable.

1A, 1B and 1C show an articulated arm assembly 10 according to the present invention. Joint arm assembly 1
0 comprises a pair of first front arms 12 and 13 and a pair of second front arms 14 and 15. Each forearm is articulated by one upper arm (shown below the forearms 12 and 13) and by suitable means such as a pin connection 16. These front arms are driven by upper arms 17 and 18 (see FIG. 1B).

1A, 1B and 1C show three basic positions of the articulated arm assembly 10. Figure 1A
Shown is the assembly 10 in a substantially fully left extended position relative to the base 19. FIG. 1B shows assembly 10 in a rest or “home” position with respect to base 19. And FIG. 1C shows the assembly 10 in a substantially extended right position relative to the base 19.

As shown in FIG. 2, upper arms 17 and 18 are shown.
Generally comprises circular gears 20 and 21, respectively.
Gears 20 and 21 may be integrally formed as part of upper arms 17 and 18, or may be individually formed and then secured to the upper arms by any suitable fastening method. The gear 20 is operably connected to the drive pinion 22. The gear 20 is driven by the drive pinion 22, and the gear 20 drives the gear 21. Drive gears 20 and 21
The pinion 22 may be replaced by any suitable drive mechanism such as a friction surface or band and drum assembly. 2B, 2C and 2D show a suitable band drum assembly. In these figures, the drum 100 is connected to the drum 101 by two bands 102 and 103. The band 102 is attached to the drum 1 by screws 104 (or other attachment means such as rivets or welding).
01, and the band 102 is fixed to the drum 100 by screws 105. The band 103 has a screw 10
It is fixed to the drum 100 by 7. Band 103
Are fixed to the drum 100 by screws 107. The bands 102 and 103 are tensioned and they may be made of metal. Each band has a generally S-shape, which is inverted in the two bands. Thus, when the band 100 rotates clockwise, the screw 105 pulls the band 102, which pulls the screw 104 and the drum 101 rotates counterclockwise. When the band 100 rotates counterclockwise, the screw 107 pulls on the band 103, which pulls the screw 106 and causes the drum 101 to rotate clockwise. Thus, when either drum 100 or 101 rotates, the other drum rotates in the opposite direction.

As shown in FIG. 4, the front arms 12 and 13 are
The wrist joint part of (1) is provided with anti-rotation gears 23 and 24 having a semicircular shape. The pedestal (or end effector or other suitable retainer) for transporting the articles may include anti-rotation gears 23 and 2
4 by means of bearings 26 and 27. The anti-rotation gears 23 and 24 may be replaced by any suitable means to prevent rotation of the ends of the upper arms 12 and 13 such as friction surfaces or drum band assemblies. Similarly, the front arms 14 and 15 are provided with an anti-rotation gear and the like and a mounting table connected thereto.

When the drive pinion 22 rotates clockwise, the gear 20 and the drive arm 17 rotate counterclockwise,
Obviously, the gear 21 and the drive segment 18 rotate clockwise.

As a result, the front arms 14 and 15 are pulled back in a "frog-like" motion, causing the mounting table 25 'to move to the drive gear 20.
And move toward 21. Anti-rotation gears 23 'and 2
The reference numeral 4'prevents the turning of the mounting table 25 ', so that the transferred object can be linearly moved.

When the mounting table 25 'is pulled back towards the drive gears 20 and 21, the front arms 12 and 13 are angled "a" between their upper arms 12 and 13 (see FIG. 4).
Move to get bigger. However, the pedestal 25, which is in a position that extends well beyond the drive gears 20 and 21 and extends completely to the left, accelerates very slowly from a standstill until it reaches maximum speed at the stop shown in FIG. 1B. (Control by motion control curve). Then, the table 25 '
Moves toward a position well beyond the drive gears 20 and 21, and the front arms 12 and 13 continue to extend.

For various reasons, the front arms 12, 1
The length of 3, 14, and 15 (ie, the distance between the pivot axes plus the separation distance between the wrist pivot axis and the centerline) is equal to the length of the upper arms 17 and 18 (ie, the pivot axis). (The distance between the shoulder pivot axis and the center line). To achieve smooth movement, the forearm may be set slightly longer (eg, about 0.25 inch) than the upper arm. The length of this front arm depends on the size of the transferred object. The larger the item, the longer the arm needs to be set.

FIG. 2 is an exploded isometric view of a conventional device that can also be used with the present invention. The joint arm assembly 10 is arranged on the C-shaped support 30 via shoulder joints 50 and 51. The electric motor 31 is attached to the support 30 and is connected to the drive pinion 22. The drive pinion engages the gear 20, which drives the gear 21, thereby extending and contracting the articulated arm assembly 10 as described above. The support 30 is connected to a shaft 32 that is axially supported by the second C-shaped support 33. The shaft 32 includes a rotary gear 34 connected to an electric motor 35, and rotates the joint arm assembly 10 as a whole. According to the invention, when the arm is once in the rest position, the mounting tables 25 and 25 'are
Nearly centered on axis 32, centrifugal forces on the substrate or substrates being transferred can be minimized. The support 33 is connected to the base 36 via C-shaped supports 37 and 38 and flexible bodies 41 to 44. A lifting mechanism 40 such as a solenoid is arranged on the base 36 and is connected to a lever 45. The lever 45 is arranged below the shaft 32. One end of the lever 45 acts as a first fulcrum 46 arranged on the base 36, and a second fulcrum (see FIG. 2A) is arranged at the bottom of the shaft 32. When the mechanism 40 is actuated, the shaft 32 is displaced upward in the axial direction to bend the flexible bodies 41 to 44. Obviously, when the shaft 32 is axially displaced, the articulated arm assembly 10 is also generally axially displaced.

In accordance with the present invention, one or more of motors 31 and 35 and lift mechanism 40 are controlled by electronic logic circuitry (not shown in FIG. 2) to precisely control articulated arm assembly 10. Controlled.

The front arms 12, 13, 14 and 15 are
The joints are connected to the upper arms 17 and 18 by any suitable means so as not to adversely affect the movement. Figure 3
Shows an example of a single axis elbow joint where each forearm facing each other is coupled to the same axis. The front arm 15 is provided with a C-shaped portion 80 having a hole through which an elbow shaft 82 passes at the connecting end thereof. Similarly, the front arm 13 is provided at its connecting end with a C-shaped portion 81 having a hole through which the elbow shaft 82 passes. The elbow shaft 82 is fixed to the upper arm 18 and cooperates with the upper arm 18 to form an elbow joint. Front arm 13
Has a stepped portion 83, and the mounting table 25 is in the same horizontal plane as the mounting table 25 '.

5 and 6 show an example comparing the operation of the device of the present invention with the operation of a conventional device having only a pair of front arms. In these figures, a module (structural unit) 1 shows an area where a wafer is processed, and modules 2 and 3 show areas where a processed wafer and an unprocessed wafer are held. Tables 1 and 2 show the position of the articulated arm assembly and the state of the process module corresponding to FIGS. 5 and 6, respectively.

Table 1 FIG. 5 Position of Joint Arm Assembly Module 1 State a Remove wafer A from module 3 Operation (process wafer B) b Stop temporarily Inoperate (processing of wafer B is completed) c Remove wafer B from module 1 Inactive d Stop temporarily inactive e Rotate 180 ° f Inactive f Wafer A is not placed on module 1 Inactive g Temporary stop operation (wafer A is processed) h 90 ° rotation operation i Wafer B is placed on module 2 Operation j

Table 2 FIG. 6 Position of Articulated Arm Assembly State of Module 1 a temporarily stopped and inoperative (processing of wafer B completed) b inoperative to take wafer B out of module 1 inactive c temporarily stopped inactive d 90 ° rotation and wafer B placed on module 2 inactive e temporarily stopped inactive f 90 ° Rotation and taking out wafer A Inactive g Temporarily stopped inactive h 180 ° Rotated inactive i Wafer A placed on module 1 Inactive j j Temporarily stopped Operation (wafer A processing)

From the above, it can be seen that the composite arm of the present invention has the advantage of minimizing down time of the process module, thereby increasing the throughput of the system.

The present invention also provides that when the first end effector is extended to transfer the substrate to the process module, the center of the substrate on the second end effector is beyond the position of the drive shaft and the open process. It has the advantage of never approaching the module. By this, the second
The substrate is not contaminated by gases or particles or is affected by heating or cooling in the vicinity of open process modules. FIG. 7 illustrates this feature of the invention in detail.

FIG. 8 shows a state in which the same arm is once in the stop position. In this design, the end effector comes very close to the center of rotation when the arm is in the rest position.

Electronic or mechanical means can be used to control the velocity and / or acceleration curves for end effector movement. As shown in FIG. 11, a typical system that gives an operation pattern is IBM.
PC computer and a harmonic drive (RH) connected to the computer via a serial communication line.
-11 6001-E100A) gearmotors /
It consists of a Brooks Automation control PC board # 11951 that controls the encoder package.

While the principle of the present invention has been described with the embodiments, the specific expressions in the embodiments are comprehensive examples and limit the scope of the present invention described in the claims below. is not.

[Brief description of drawings]

FIG. 1A is a plan view of an articulated arm assembly according to the present invention in a left extended position.

FIG. 1B is a plan view of an articulated arm assembly according to the present invention in a rest position.

FIG. 1C is a plan view of an articulated arm assembly according to the present invention in a right extended position.

FIG. 2 is an isometric view of a conventional device used in an embodiment of the present invention.

2A is a side view of the device shown in FIG. 2. FIG.

FIG. 2B is a side view of the band-drum assembly.

2C is a cross-sectional view taken along line 2C-2C of FIG. 2B.

2D is a cross-sectional view taken along line 2D-2D of FIG. 2B.

FIG. 3 is a side view of an articulated arm assembly according to the present invention.

4 is a partial plan view of the articulated arm assembly of FIG.

FIG. 5 is a schematic diagram showing a processing sequence using the articulated arm assembly according to the present invention.

FIG. 6 is a schematic diagram showing a processing sequence using a conventional device.

FIG. 7 is a diagram showing a state where one wafer is in the processing chamber and another wafer is in the pullback position.

FIG. 8 is a diagram showing a state in which the arm in FIG. 7 is at a stop position.

FIG. 9 is a block diagram of a typical motion control servo.

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Claims (4)

[Claims] 1. An apparatus for conveying an object (A, B), comprising two upper arms (17, 18) rotatably connected to a support (19) and two pairs of front arms. The front arm of each pair is
Two pairs of front arms (12, 13, 14, 1) rotatably connected to respective opposite outer ends of the two upper arms.
5), a first object holding means (25) connected to the first pair of front arms (12, 13), and a second object connected to the second pair of front arms (14, 15). An object transfer device comprising: an object holding means (25 '); and means for vertically moving the holding means (25, 25'). 2. A mechanical coupling (20,2) between the two upper arms (17,18) for rotating the two upper arms (17,18) together in opposite directions.
The apparatus of claim 1, further comprising 1). 3. Further comprising means connected to said support (19) for moving said support in a direction substantially parallel to a first axis of a first arm of said upper arms, The device of claim 1. 4. A device (10) for transporting semiconductor substrates, comprising two drive arms (17, 1) connected to a support (19).
8) and two pairs of driven arms, each pair of driven arms being rotatably connected to opposite outer ends of the two driving arms. , 14, 1
5), a first substrate holding means (25) connected to the first pair (12, 13) of the driven arms, and a second pair (14, 15) of the driven arms. Second substrate holding means (25 ');
The drive arms are rotatable towards and away from each other, thereby moving two pairs of driven arms, which are thereby related to the range of rotation of the two drive arms connected to the support. Then, it is possible to extend and retract the first and second substrate holding devices, and a device for transporting the semiconductor substrate.