JPH0687507A - Substrate carrying device - Google Patents

Abstract

PURPOSE:To provide a carrying device, with which carrying can be performed with a small number of driving shafts, and which occupies narrower space. CONSTITUTION:Two substrate support arms 11, 12 having a specific length, are provided point-symmetrically to a rotating arm support member 3 and the rotation shaft of the arm support member 3. The arm support member 3 is rotated while the two substrate support arms are situated in parallel to one another, and the substrate arms 11 and 12 are crossed to each other, and a substrate R is thus transferred.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate transfer apparatus, and more particularly to a substrate transfer apparatus for transferring an original plate such as a reticle used in a semiconductor manufacturing process while keeping its orientation constant.

[0002]

2. Description of the Related Art A conventional device of this type will be described with reference to FIGS. Although there are various conventional substrate transfer methods, the movement becomes a little complicated if there is a restriction that the orientation of the substrate after transfer does not change. The transfer from the substrate case C supporting both ends of the substrate as shown in FIG. 6 to the arm A supporting both ends of the substrate will be described as an example.

FIG. 7 is a diagram showing a method of transporting a substrate by transferring a substrate between two arms, and FIG. 8 is a diagram showing a method of transporting a substrate by a rotating arm. First, the transport method of FIG. 7 will be described. As shown in FIG. 7a, the U-shaped substrate receiving arm p enters the space below the substrate R housed in the case C, and the substrate receiving arm moves in the vertical direction (Z direction) to move the substrate R to the substrate case C. Receive from. Then, the receiving arm p is moved horizontally (X
Direction). Next, the substrate transfer arm q having a U-shape opposite to the substrate receiving arm p described above moves upward from below the substrate receiving arm p to change the substrate R. The delivery arm q that has changed the substrate R carries the substrate R to a position above the arm A. The transfer arm q moves downward (Z direction), and the substrate R is placed on the arm A to complete the transfer. In this mechanism, the two arms have a total of four vertical (Z) and horizontal (X) directions.
Axial drive is required. FIG. 7b is a diagram showing a case where the substrate R is transported from the arm A to the substrate case C. In FIG. 7b, the vertical relationship between the receiving arm p and the delivery arm q is reversed from that in FIG. 7a. The transfer arm q receives the substrate R from the arm A. Then, the receiving arm p located below the transfer arm q moves upward (Z direction) and receives the substrate R. Then, the receiving arm p moves in the X direction to the vicinity of the case C. The receiving arm p moves in the vertical direction (Z direction) and stores the substrate R in the case C.

Next, the carrying method of FIG. 8 will be described.
The transfer example of FIG. 8 is a transfer method using a substrate support arm provided with a turntable r. FIG. 8a shows a state in which the substrate R is received from the case by moving in the vertical and horizontal directions.
After that, the arm s rotates 180 degrees around the arm support shaft M. In this state, the orientation of the substrate R rotates 180 degrees, but the turntable r rotates 180 degrees on the arm s to correct the orientation of the substrate to the initial orientation. After that, the arm s conveys the substrate above the arm A at the position 2, and the arm s moves downward (Z direction) to place the substrate R on the arm A.
The transfer of the substrate R is completed by these series of operations. Also in this method, it is necessary to drive the turntable r and the arm s support shaft M, and drive the arm in vertical and horizontal directions in a total of four axial directions. In this case, if the two rotary shafts are connected by a belt or the like, the number of rotary drive sources can be reduced by one, and the total number of drive sources can be three. Also,
In this case, a rotation radius space is required for the arm s to rotate about the support shaft M.

Although there are several transfer methods other than those shown in FIGS. 7 and 8, in any case, at least three drive sources are required for taking out the board from the case and correcting the board attitude. Become.

[0006]

In the prior art as described above, if there is a constraint that the orientation of the substrate after transfer does not change, the number of drive shafts increases and the mechanism is complicated with respect to the simple movement of the substrate. It was. Further, in the case of FIG. 8, it is necessary to secure a space for rotating the arm shaft, which prevents space saving.

[0007] Therefore, an object of the present invention is to use a rotating mechanism to carry with a smaller number of drive shafts and to save space.

[0008]

In order to solve the above problems, the present invention provides a substrate transfer apparatus for transferring a substrate by handing without changing the direction of the flat plate (R).
A first substrate supporting arm (1 having a predetermined shape capable of supporting the substrate)
1) and; a second substrate supporting arm (12) capable of supporting the substrate and having a shape different from that of the first substrate supporting arm.
And an arm supporting member rotatable about a main rotating shaft, the first substrate supporting arm being supported by one end of the arm supporting member so as to be rotatable around a first rotating shaft parallel to the main rotating shaft. An arm supporting member (3) for supporting the second substrate supporting arm at the other end of the arm supporting member so as to be rotatable about a second rotating shaft parallel to the main rotating shaft; Drive means for rotating as (4)
Interlocking with the rotation of the arm supporting member, the first substrate supporting arm and the second substrate supporting arm are relative to the arm supporting member, and the first substrate supporting arm and the second substrate supporting arm are always horizontal. Interlocking means (9, 10) for rotating so as to maintain such a state, the first substrate supporting arm and the second substrate supporting arm move to the first with the rotation of the arm supporting member.
When located in the space between the rotating shaft and the second rotating shaft, the first substrate supporting arm and the second substrate supporting arm can pass in the opposite directions in the space without interfering with each other, and the substrate The size and shape of the first substrate support arm and the second substrate support arm were determined so that the substrate could be delivered.

[0009]

In the present invention, since the rotation transfer mechanism is used, the substrate support arms for receiving and transferring the substrates are driven by the same drive system, and the drive shaft of the transfer system can be reduced. For this reason, the apparatus can be simplified and at the same time the transport space can be reduced.

Further, when the posture of the arm supporting member rotates and approaches the horizontal direction, each substrate supporting arm extends in the horizontal direction so as to move away from the main rotation axis, and thus this operation serves as the horizontal conveying. Therefore, there is also an advantage that the horizontal movement of the arm support member is unnecessary or can be shortened when the transport distance from the storage section to the transport destination is short.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of a substrate transfer device suitable for the first embodiment of the present invention. The reticle case 1 is provided with a shelf 1a so as to have a predetermined space.
A substrate (reticle, mask, etc.) R is placed on a. Arm support member 3 for fixing the support arms 11 and 12
Is supported by the fixed member 2 and the arm support member 3
Can be rotated about a rotation axis Σ by a drive unit 4 such as a motor. The fixing member 2 is a drive unit 5 such as a motor,
The ball screw 8 can move in the X direction along the linear guide 6. The control device 14 controls the positions of the fixed member 2 and the rotation amounts of the arm support member 3 and the support arms 11 and 12 by controlling the drive amounts of the drive units 4 and 5. The controller 14 controls the respective positions, and also controls the substrate 1
Control of the entire device such as receiving, delivery, and conveyance in the X direction. Rotation angle of arm support member 3 and fixing member 2
The positions of are determined by the rotation angles of the drive units 4 and 5, respectively, but by attaching an encoder or the like for position detection to the drive units, information on each position control can be obtained.

The support arm 11 receives the substrate R of the case 1, the support arm 12 approaches the support arm 11 from below, and receives the substrate R on the support arm 11. Then, the support member 2 moves in the X direction, and the support arm 12 transfers the substrate R to the arm 13. Now, FIG. 2 is a schematic view showing a rotation mechanism for delivering a substrate in the apparatus of FIG. The arm support member 3, the support arms 11 and 12, and the drive unit 4 realize a rotation mechanism that keeps the orientation of the substrate R constant and saves space. Each of the support arms 11 and 12 is a U-shaped substrate support arm, and each arm has a rotation axis α ₁ ,
It is attached to the arm support member 3 via the rotation axis α ₂ . The arm support member 3 is attached to the fixed member 2 so as to be rotatable about the rotation axis Σ.

Further, the support arm 11 and the support arm 12 are attached to the arm support member 3 so that they are always parallel to each other. Even if the arm support member 3 rotates about the rotation axis Σ, The parallel relationship with the support arm 12 is maintained. A belt 9 and a belt 10 are provided as a mechanism for keeping the postures of the support arms 11 and 12 always parallel.

One side of the belt 9 is hung on a pulley 20 having a rotation axis α _1, and the other side of the belt 9 is hung on a cylindrical fixing member 21. The fixing member 21 is provided on the fixing member 2 separately from the arm supporting member 3, and the central axis of the bottom surface of the fixing member 21 coincides with the axis Σ. The diameter of the pulley 20 and the diameter of the bottom surface of the fixed member 21 are equal, and the rotation angle of the arm support member 3 with respect to the axis Σ and the rotation angle of the arm support member 11 with respect to the axis α ₁ are opposite in direction and equal in size. . Similarly, one of the belts 10 has a rotation axis α ₂
The belt 10 is hung on a pulley 22 and the other side of the belt 10 is hung on a cylindrical fixing member 21. The diameter of the pulley 22 and the diameter of the bottom surface of the fixed member 21 are equal, and the rotation angle of the arm support member 3 with respect to the axis Σ and the rotation angle of the arm support member 12 with respect to the axis α ₂ are opposite in direction and equal in size. . The belt 9 and the belt 10 are fixed members 21.
The belts 9 and 10 are hung at different positions with respect to the direction of the axis Σ so that the belt 9 and the belt 10 do not overlap each other. The arm support member 3 can be rotationally driven about the axis Σ by the drive unit 4.

The support arms 11 have a space L1 and a length M1.
And is large enough to hold the substrate R. The support arms 12 have a space L2 and a length M2, and are large enough to hold the substrate R. In this embodiment, the distance L2 is set to be larger than the distance L1 so that the support arms 11 and 12 do not interfere (clash) with each other when they are located in the same plane. The arm support member 3 is a frame-shaped member having a hollow portion having a size capable of passing the substrate R and the support arms 11 and 12. That is, the space L between the arm support members 3 is larger than the space L1 and the space L2, and the space between the arm support members 3 is large.
The length M of the support arm 11 is the length M1 of the support arm 11 or the support arm 12
Is greater than the length M2. As will be described later, when the substrate R is delivered, the arm supporting member 3, the supporting arm 11, and the supporting arm 12 are located in substantially the same plane, and the respective members are supported by the supporting arm 11 without interfering with each other. It is delivered to the arm 12.

The structure of the rotating mechanism is not limited to that shown in FIG. 2, and the same effect can be obtained even when the supporting arms 11 and 12 are cantilevered. Here, the cantilevered state means a state in which the arm supporting member 3 is not a frame-shaped member but a rod-shaped member and holds the supporting arms 11 and 12 only on one side. Further, the support arms 11 and 12 may have the same size and may be arranged with a slight shift so as not to interfere with each other in the same plane.

FIG. 3 is a diagram for explaining the transfer operation of the substrate R. For example, the transfer operation of the substrate R from the support arm 11 to the support arm 12 will be described using eight operations. First, the control device 14 controls the rotation of the arm support member 3 and the position of the fixed member 2 so that the support arm 11 picks up the substrate R from below. Next, the arm supporting member 3 is rotated counterclockwise (rotational direction indicated by an arrow in the drawing), so that the substrate R moves.
Approach the center of rotation. When the arm support member 3 is in a substantially horizontal state, the support arms 11 and 12 are also in a substantially horizontal state. Further, the rotation of the arm support member 3 continues, the support arm 12 approaches from below the support arm 11 holding the substrate R, and the substrate R is picked up and received. As a result, the substrate R is switched from the support arm 11 to the support arm 12 (operation 5). At the time of this holding, the arm supporting member 3 and the supporting arms 11 and 12 become substantially linear (the supporting arms 11 and 12 are closest to the arm supporting member 3).

The rotation of the arm support member 3 continues as it is,
The substrate R on the support arm 12 moves away from the rotation center of the arm support member 3. After that, the substrate R on the arm support member 12 is placed on the arm 13 in FIG. 1, and the transfer is completed.
The movement in the horizontal direction (X direction) is not limited to the ball screw as long as the position can be controlled as in the present embodiment.

Further, as shown in operation 2, the arm support member 3 is rotatable about the rotation axis Σ, and the rotation axis α
The midpoint between ₁ and the rotation axis α ₂ coincides with the rotation axis Σ.
Further, in the state of operation 2, the right side of the support arm 11 has a U-shaped opening, and the left side of the support arm 12 has a U-shaped opening. In this way, the support arm 11 and the support arm 12 are arranged so as to be point-symmetrical with respect to the rotation axis Σ.

A second embodiment of the present invention will be described with reference to FIG. The same members as those in FIG. 1 are designated by the same reference numerals. This embodiment has a short transport distance in the horizontal direction (X direction), and is particularly effective in the case where the horizontal movement can be compensated by the rotation of the link without providing a horizontal transport mechanism. The configurations of the support arms 11 and 12 and the arm support member 3 are the same as those in the first embodiment. The posture maintaining mechanism for the support arms 11 and 12 (belts 9 and 10 in FIG. 2) is not shown in the figure, but may be provided inside the arm supporting member 3, and a link mechanism is used instead of the belt mechanism. You can also

In this embodiment, the rotating shaft Σ of the arm supporting member 3 is one rotating shaft of the link 15 having rotating shafts at both ends, and the rotating shaft β at the other end is the link 15 and the fixing member 17 supporting the same. It is the axis of rotation with. The arm support member 3 is rotatable by a drive unit 4 fixed to a link 15, and the link 15 is rotationally moved about a rotation axis β by a drive unit 16 such as a motor fixed to a fixed member 17. The controller 14 controls the rotation angles of the drive unit 4 and the drive unit 16. In this embodiment, a command line (code) from the control device 14
Passes through the inside of the link 15 and the fixing member 17,
Not shown in the figure. Link the code 15, like this,
By passing the fixing member 17 inside, the appearance of the device can be simplified.

As described above, according to the present embodiment, there is an advantage that the horizontal movement of the fixing member 2 is unnecessary or can be shortened when the distance from the case to the transport destination is short. Next, a third embodiment of the present invention will be described. The same members as those in the first embodiment are designated by the same reference numerals. In this embodiment, two transfer support arms 12 according to the first embodiment are provided so that two types of substrates having different sizes can be selected and conveyed.

The basic operation will be described with reference to FIG.
In operations 1 to 5 in the figure, the receiving support arm 11 is the substrate.
Support R and turn counterclockwise in the figure (the direction of rotation indicated by the arrow in the figure)
It shows how it is rotating. Large support arm 12
The support arm 12b for supporting the substrate is an arm for supporting the small substrate.
It is. The support arm 11 has a rotation axis α.₁, Support arm 1
2 is the rotation axis α₂, The support arm 12b has a rotation axis α.₃Through
And is supported by the arm support member 3. Support arm 11
And the support arm 12b are the rotation axis α₁And rotation axis α ₃Inside
Point N₁Are arranged in a point-symmetrical relationship with respect to
The arm 11 and the support arm 12 have a rotation axis α.₁And rotation axis α₂
Midpoint N with₂Are arranged in a point-symmetrical relationship with respect to
(See operation 1).

The U-shaped space (span) of the three arms has a predetermined relationship. That is, the span of the support arm 11 is La and the span of the support arm 12 is Lb.
₁ , the span of the support arm 12b is Lb ₂ , the size of the large substrate is L1, and the size of the small substrate is L2, the relationship of L1> Lb ₁ >L2> Lb ₂ > La is satisfied. The support arms 11, 12, 1
The span of 2b is described as the inner dimension of the U-shape,
At this time, the inner and outer dimensions of the support arm are determined so that the arms do not overlap each other on the same plane.

In the case of carrying a large substrate, the support arm 12 receives the substrate R from the support arm 11 as shown in operations 6 to 8 of FIG. Operations 9 to 14 in FIG. 5 show the case of small substrate transfer. Since the span Lb ₁ of the support arm 12 is larger than the size L2 of the small substrate, the support arm 12 passes through as it is (see operation 9). When the arm supporting member 3 continues to rotate and the supporting arm 12b becomes the same height as the substrate supporting arm 11, the substrate is transferred (see operation 10). After that, the arm supporting member 3 continues to rotate and the substrate is delivered. Also in this embodiment, each arm is maintained in a posture such that it is always horizontal by a posture maintaining mechanism (belts 9 and 10 in FIGS. 1 and 2).

In this way, substrates of different sizes can be selected and transported. Further, the number of support arms 12 for delivery may be three or more. in this way,
According to the present embodiment, by providing a plurality of support arms for delivery having different sizes, it is possible to realize the transfer of the substrates R having different sizes with one device. Further, in the above-described embodiment, the posture maintaining mechanism has the substrate supporting arms (11, 12,
Although the postures of the respective substrate support arms are maintained so that 12b) is always horizontal, the postures are not necessarily limited to the horizontal posture. Each substrate support arm is provided with a suction mechanism or the like, and if the substrate R does not fall even if the substrate support arm is tilted, the postures are maintained so that the arms are parallel to each other. Just do it.

Further, in any of the above-mentioned embodiments, the substrate supporting arm (11, 12, 12b) is not limited to the U-shaped arm. For example, frame-shaped substrate support arms having different sizes may be used. Further, for example, in the first embodiment, the substrate support arm 11 may be a frame-shaped substrate support arm and the substrate support arm 12 may be a U-shaped arm, or the substrate support arm 11 may be a frame-shaped or U-shaped arm. The substrate support arm 12 may be a plate-shaped substrate support arm smaller than the substrate support arm 11.

[0028]

As described above, according to the present invention, it is possible to reduce the number of drive shafts when carrying the substrate without changing the direction of the substrate, and at the same time, it is possible to carry in a small carrying space.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a substrate transfer apparatus suitable for a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a rotation mechanism portion of the apparatus of FIG.

FIG. 3 is a diagram for explaining a substrate transfer operation by the apparatus of FIG.

FIG. 4 is a diagram showing a schematic configuration of a substrate transfer apparatus suitable for a second embodiment of the present invention.

FIG. 5 is a diagram showing a support arm and a delivery operation according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a substrate case and a transfer target position.

FIG. 7 is a diagram showing a substrate transfer device according to a conventional device using two arms.

FIG. 8 is a diagram showing a substrate transfer device by a conventional device using a rotating arm.

[Explanation of symbols]

R ... Substrate Σ Main rotation axis α ₁ , α ₂ ... Support arm rotation axis M ... Arm support member length L ... Arm support member width M ₁ , M ₂ ... Arm length L ₁ , L ₂ ... Arm Width 1 ... Substrate case 2 ... Fixing member 3 ... Arm support member 4, 5 ... Driving mechanism 9, 10 ... Belt 11, 12 ... Support arm 13 ... Arm (conveyance destination) 14 ... Control device

Claims (16)

[Claims] 1. A substrate transfer device that transfers and transfers a flat substrate without changing its orientation, and a first substrate support arm having a predetermined shape capable of supporting the substrate; capable of supporting the substrate. And a second substrate support arm having a shape different from that of the first substrate support arm;
An arm support member rotatable about a main rotation axis,
While supporting the first substrate support arm at one end of the arm support member so as to be rotatable about a first rotation axis parallel to the main rotation axis, and centering around a second rotation axis parallel to the main rotation axis. An arm support member that rotatably supports the second substrate support arm at the other end of the arm support member; drive means that rotates the arm support member about the main rotation axis; rotation of the arm support member In a state where the first substrate support arm and the second substrate support arm are relatively horizontal with respect to the arm support member, and the first substrate support arm and the second substrate support arm are always horizontal. Interlocking means for rotating so that the first substrate supporting arm and the second substrate supporting arm rotate with the rotation of the arm supporting member. Space between When located in the first
The first substrate support arm and the second substrate support arm can pass through the substrate support arm and the second substrate support arm in opposite directions in the space without interfering with each other, and can transfer the substrate. A substrate transfer apparatus characterized in that the size and shape of the substrate are defined. 2. The apparatus according to claim 1, wherein the interlocking means is a belt mechanism. 3. The apparatus according to claim 1, wherein the interlocking means is a crank mechanism. 4. The arm supporting member is provided so that the transfer of the substrate is completed by the second substrate supporting arm approaching the substrate held on the first substrate supporting arm from below. The device of claim 1, wherein the device rotates. 5. An arm supporting member between the first rotating shaft and the second rotating shaft has a linear supporting portion, and is located near a center point between the first rotating shaft and the second rotating shaft. The device according to claim 1, wherein the main rotating shaft is provided. 6. The apparatus according to claim 1, wherein the first substrate support arm and the second substrate support arm are arranged in a substantially point-symmetrical positional relationship with respect to the main rotation axis. 7. An arm supporting member between the first rotating shaft and the second rotating shaft has a supporting portion bent at a predetermined angle, and the main rotating shaft is provided in the vicinity of the bent portion. The device according to claim 1, characterized in that 8. The first substrate support arm and the second substrate support arm have a substantially point-symmetrical positional relationship with respect to a virtual center point near a center point between the first rotation axis and the second rotation axis. 8. A device according to claim 7, characterized in that it is arranged. 9. The apparatus according to claim 1, wherein the first substrate support arm and the second substrate support arm are provided in different shapes in the same plane. 10. The apparatus according to claim 1, wherein the first substrate support arm and the second substrate support arm are provided at different positions on the same plane. 11. The apparatus according to claim 1, further comprising moving means capable of moving the arm supporting member. 12. The apparatus according to claim 1, further comprising a link mechanism having at least two rotary shafts, one of which is the main rotary shaft, capable of transporting the substrate. 13. A substrate transfer device for transferring and transporting a flat plate-like substrate without changing its orientation; a first substrate support arm having a predetermined shape capable of supporting the substrate; and capable of supporting the substrate. And a second substrate support arm having a shape different from that of the first substrate support arm;
A third substrate support arm capable of supporting the substrate and having a different shape from the first substrate support arm and the second substrate support arm; rotatable about a main rotation axis; An arm support member having three ends as a center, wherein the first substrate support arm is rotatably supported by a first end of the arm support member so as to be rotatable around a first rotation axis parallel to the main rotation axis. The second substrate support arm is supported by the second end of the arm support member so as to be rotatable about a second rotation axis parallel to the main rotation axis, and the third rotation parallel to the main rotation axis is supported. An arm support member that supports the third substrate support arm at a third end of the arm support member so as to be rotatable about an axis; drive means that rotates the arm support member about the main rotation axis; When the arm support member rotates The first substrate support arm, the second substrate support arm, and the third arm substrate support arm relative to the arm support member, and the first substrate support arm and the second substrate support arm. And the third
A substrate supporting arm and an interlocking device for rotating the substrate supporting arm so as to maintain a horizontal state at all times, and with the rotation of the arm supporting member, the first substrate supporting arm and the second substrate supporting arm have the first structure. When located in the space between the rotating shaft and the second rotating shaft, the first
The first substrate support arm and the second substrate support arm can pass through the substrate support arm and the second substrate support arm in opposite directions in the space without interfering with each other, and can transfer the substrate. Of the first substrate support arm and the third substrate support arm are located in the space between the first rotation shaft and the third rotation shaft. 1 substrate support arm and the third
The substrate supporting arm and the substrate supporting arm can pass through the space in opposite directions without interfering with each other, and the size and shape of the first substrate supporting arm and the third substrate supporting arm are determined so that the substrate can be delivered. In addition, when the second substrate support arm and the third substrate support arm are located in the space between the second rotation shaft and the third rotation shaft,
The second substrate supporting arm and the third substrate supporting arm can pass through in the opposite directions in the space without interfering with each other, and the substrate can be delivered and received so that the second substrate supporting arm and the third substrate supporting arm can be delivered. A substrate transfer device, wherein the size and shape of the substrate support arm are determined. 14. A distance between the first rotating shaft and the second rotating shaft, a distance between the first rotating shaft and the third rotating shaft, and a distance between the second rotating shaft and the third rotating shaft. 14. The apparatus according to claim 13, wherein the distance is larger than any length of the first substrate support arm, the second substrate support arm, or the third substrate support arm. 15. The first substrate supporting arm and the second substrate supporting arm are arranged in a point-symmetrical positional relationship with respect to a midpoint between the first rotating shaft and the second rotating shaft. 14. The apparatus according to claim 13, wherein the substrate support arm and the third substrate support arm are arranged in a positional relationship that is point-symmetrical with respect to a midpoint between the first rotation axis and the third rotation axis. 16. The distance between the first substrate support arms is La,
When the distance between the second substrate supporting arms is Lb1 and the distance between the third substrate supporting arms is Lb2, the relationship of Lb1>Lb2> La is satisfied, and the second substrate supporting arms are placed on the first substrate supporting arm. 14. The apparatus according to claim 13, wherein the arm support member rotates so that the second substrate support arm can receive the substrate before the third substrate support arm.