JP2002329769A - Alignment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alignment equipment for realizing centering of a work by certainly sucking the work after correcting the warp of the work even the work supposed to be flat has a warp. SOLUTION: The alignment equipment comprises a table 11 with a suction function rotatably provided in-plane, a transfer means 30 for transferring the table 11 in X and Y directions, a mounting means 50 for mounting the work W on the table 11, a blower 60 for blowing air from upside to the work W and a sensor 70 for detecting the area of the peripheral portion of the work W by rotating the table 11. The blower 60 corrects a wrap of the work on the table when the work on the table has a wrap, thus the work W is placed flat and rotated on the table so that the sensor 70 can detects the peripheral portion W1 in precision.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment apparatus, and more particularly, to an alignment apparatus capable of performing centering in a state where a plate-shaped work is warped while correcting the warp.

[0002]

2. Description of the Related Art Conventionally, after a circuit surface is formed on one surface of a semiconductor wafer (work), for example, a dicing process of cutting a predetermined chip size through a process of polishing the back surface while protecting the circuit surface with a film. Has been adopted.
When transferring a wafer in the dicing process, it is necessary to accurately grasp the center of the wafer in order to maintain the position of the wafer with high accuracy.

Therefore, at a stage prior to the dicing step, wafers taken out of a cassette containing a large number of wafers are transferred to an alignment device, and the center position of the wafer is accurately determined by the alignment device. Is adopted. This alignment apparatus transfers a wafer to a table, rotates the wafer in a horizontal plane while adsorbing the wafer, detects an outer edge portion of the wafer with an optical sensor, and moves the table in the X and Y axis directions based on the detection result. To accurately position the center of the wafer. Therefore, the centered wafer on the alignment device is always kept at a fixed position when the wafer is transferred to the dicing device via a predetermined transfer arm.

Incidentally, the thickness of a semiconductor wafer is 200 μm.
m, and when the wafer itself has a certain degree of rigidity, the planar shape can be maintained, and therefore, the wafer can be sucked without any trouble by the table of the alignment device having the suction holes. By rotating the table, it is possible to detect a deviation of the center position of the wafer by the sensor.

[0005]

However, recently, there has been a demand for a very thin wafer having a thickness of about 50 μm to 200 μm, and in many cases, a polished wafer will be warped. In the conventional type of alignment apparatus, there arises a problem that the wafer cannot be accurately suctioned on the table. Further, the position of the outer periphery of the warped wafer may be displaced up and down by 10 mm or more, and when a sensor is input through the lens of the optical system sensor, the position of the wafer is out of focus. there were. In order to correct this warpage, the wafer can be pressed to form a planar shape. However, since a circuit is usually formed on the upper surface side, a pressing force cannot be directly applied.

[0006]

SUMMARY OF THE INVENTION The present invention was devised in view of such inconvenience, and an object of the present invention is to provide a state in which even if a workpiece to have a planar shape has a warp, the warp is corrected. It is another object of the present invention to provide an alignment apparatus which can realize centering of a work.

[0007]

In order to achieve the above object, the present invention relates to an alignment apparatus for centering a substantially plate-shaped work, wherein the work is provided so as to be rotatable in a plane, and a suction hole of the work is provided. A table provided in at least a partial area, a moving device for moving the table in the X and Y-axis directions, and a discharging device for blowing gas from a side opposite to the suction hole to a work transferred on the table And a sensor arranged near the outer edge portion of the work to detect the outer edge position, and moving the table while referring to the detection data of the sensor when rotating the table to center the work. Is made possible. According to such a configuration, the work blown by the gas discharged from the discharge device is pressed along the table surface, whereby the warped work becomes substantially parallel to the table surface, and the work is bent. Adsorption can be performed.
Therefore, the centering of the work can be performed with high accuracy by detecting the position or the movement trajectory of the outer edge of the work when the table is rotated in this state.

In the present invention, the table includes an outer table and an inner table which can be moved up and down relatively to the outer table, and the work is transferred at a position where the inner table is stepped with respect to the outer table. Done,
The configuration is adopted. According to such a configuration, when the transfer needs to be performed in a non-contact state on the upper surface side of the work, the work can be transferred to the table while supporting the lower surface side of the work. Therefore, it is particularly useful when a workpiece is a wafer having a circuit surface formed on the upper surface.

Further, the discharge device comprises an outer discharge portion and an inner discharge portion substantially corresponding to the outer table and the inner table, respectively, and the inner table sucks the work transferred to the inner table at the raised position. Gas is discharged from the inner discharge portion while descending, and when the inner table is lowered and the work is located on the outer and inner table surfaces, gas is also discharged from the outer discharge portion,
It is also good to adopt the configuration as well. With such a configuration, even if the work is supported only by the inner table at the initial stage of transfer, the work can be lowered while maintaining the support state. In addition, even if the work is warped due to the gas discharge force from the outer discharge portion, it can be corrected without difficulty, and the work can be reliably attracted to the table.

[0010] It is also possible to adopt a configuration in which a suction hole is provided in the inner table, and a discharge hole or a suction hole is provided in the outer table. In the configuration in which the discharge holes are provided in the outer table, warpage can be corrected by applying gas pressure to the work from both upper and lower surfaces by interaction with the outer discharge section. On the other hand, in the configuration in which the suction holes are provided in the outer table, the work is sucked as a whole together with the inner table, and the warp can be corrected by receiving the gas pressure from the discharge device from above.

Further, the work is made of a semiconductor wafer, and is mounted on the table with its circuit surface as an upper surface. At this time, a transfer device for transferring a work onto the table is provided near the table, and the transfer device includes an arm having a suction hole that is open to the upper surface on the distal end side. Is preferred. Thus, by incorporating the present apparatus into a semiconductor wafer production line, it is possible to improve chip processing accuracy and dramatically improve production efficiency.

Further, the present invention is directed to an alignment apparatus for centering a substantially plate-shaped work, wherein an inner table provided rotatably in a plane and provided with a suction hole for the work; A lower discharge device that is provided on the outer peripheral side and blows gas to a lower surface side of a workpiece transferred on the inner table; a moving device that moves the table in X and Y axes directions; An upper discharge device that blows gas toward the device side, and a sensor that is disposed near an outer edge portion of the work and detects the outer edge position, and the table is referred to by referring to detection data of the sensor when the table is rotated. To enable the centering of the work,
Is also adopted. With such a configuration, even if the workpiece is warped by the pressure of the gas blown out from the lower discharge device and the upper discharge device, the warp can be corrected to have a planar shape. By fixing and rotating the work with the suction force, the position or the movement locus of the outer edge portion of the work can be detected with high accuracy, and the centering of the work can be performed based on the detection result.

Further, the lower discharge device and the upper discharge device may be connected to each other through a variable distance device. With such a configuration, the lower discharge device and the upper discharge device can be brought close to each other, and the pressure on the work gradually increases with this approach, so that the warp deformation of the work is corrected in a non-contact state and the flat discharge device is corrected. It can be kept in shape. In addition, by keeping the discharge pressures from the lower discharge device and the upper discharge device in equilibrium, it is possible to keep the workpiece floating on a certain plane, and it is also possible to eliminate restrictions on the shape of the transfer arm. In addition, the degree of freedom in design can be increased.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is a schematic front view of an alignment apparatus according to a first embodiment. In this figure, an alignment apparatus 10 includes a table 11 for supporting a wafer W as a substantially disk-shaped work.
A moving device 30 for moving the table 11 in the X and Y axis directions, a rotating device 40 for rotating the table 11 in a substantially horizontal plane, and a transfer device 50 for transferring the wafer W onto the table 11 ( 3) and the table 11
Discharge device 60 for blowing gas onto the upper surface side of upper wafer W
And a sensor 70 arranged near the outer edge W1 of the wafer W.

As shown in FIG. 2, the table 11 has an annular outer table 11A, an inner table 11B disposed inside the outer table 11A, and a lower surface of the outer table 11A. Chamber 11C
(See FIG. 1). Outer table 1
1A has a maximum diameter smaller than the diameter of the wafer W, so that an outer edge portion W1 (see FIG. 2) of the wafer W can project a predetermined amount from the outer edge of the outer table 11A. A large number of suction holes 11a penetrating in the vertical direction are formed in the surface of the outer table 11A, and the inside of the chamber 11C is evacuated via a vacuum pump or a decompression pump (not shown) to form a gas on the outer table 11A. Can be sucked.

The inner table 11B has a substantially cylindrical cross-section, and has a suction hole 11 vertically penetrating through its upper end surface.
b is formed. The lower end of the inner table 11B is connected to a vacuum pump or a decompression pump (not shown), and the wafer W can be sucked by the suction holes 11b and the suction holes 11a of the outer table 11A. Further, the inner table 11B is arranged in a support cylinder 15 located on the lower surface side of the outer table 11A, and can be moved up and down via a lifting means 16 provided at the lower end side of the inner table 11B. , Inside table 11B
Can be moved up and down relatively to the outer table 11A. The inner table 11B is provided with a slidable key 18 and a key groove 19 indicated by a dotted line in FIG.
The rotation of the support cylinder 15 in the circumferential direction is restricted via the.

The moving device 30 is moved in the horizontal direction (X in FIG. 1).
An X-axis moving body 31 movably provided in the (axial direction), and a Y-axis movement provided above the X-axis moving body 31 and movably provided in the direction perpendicular to the paper surface of FIG. 1 (Y-axis direction). Body 32
Consists of The X and Y axis moving bodies 31 and 32 are equipped with a known feed screw shaft device, and can be moved with high precision along the X and Y axes by driving the motors M1 and M2, respectively. I have. A table support 35 is provided on the upper surface side of the Y-axis moving body 32. The table support 35 includes a base 36, a plurality of columns 37 extending upward from the base 36, an upper bearing plate 38 disposed at an upper end of the column 37, and a lower portion disposed at an intermediate portion inside the column 37. A support plate 15 and an outer table 11A supported by the support cylinder 15 by upper and lower bearing plates 38, 39;
The inner table 11B is rotatably supported.

The rotating device 40 includes a motor M3 supported on the lower surface of a region of the upper bearing plate 38 projecting rightward in FIG. 1, and a first pulley 42 fixed to an output shaft 41 of the motor M3. And a second pulley 43 fixed to the outer periphery of the support tube 15 and a belt 45 wrapped between the first and second pulleys 42, 43, and the motor M3 rotates. , The support cylinder 15 and the table 11 are rotatable in a horizontal plane.

The transfer device 50 (see FIG. 3) includes a transfer arm 51 having an indirect function and a robot main body 52 for moving the transfer arm 51. The transfer device 50 is for picking up wafers W one by one from a cassette of wafers (not shown) and transferring the wafers W to the table 11. The distal end side of the transfer arm 51 is a bifurcated branch portion 51A. , 51A. The branch portions 51A, 51A have suction holes 51 that are opened to the upper surface side and suction the wafer W in a state where the wafer W is mounted on the upper portion.
B are formed respectively. These suction holes 51B, 5
1B is connected to a vacuum pump or a decompression pump via a pipe (not shown). Note that the separation width of the branch portions 51A, 51A is determined by the inner table 11 described above.
The transfer arm 51 is provided to be larger than the diameter of B, so that the transfer arm 51 can move to a position where the branch portion 51A, 51A enters the inner table 11B so as to straddle the inner table 11B from the horizontal direction.

The discharge device 60 is provided with the outer table 1.
It comprises an outer ejection section 60A corresponding to 1A and the inner table 11B, respectively, and an inner ejection section 60B. The outer discharge portion 60A and the inner discharge portion 60B are formed with discharge holes 60a and 60b penetrating in the vertical direction, respectively. (Wafer W). Here, the chamber 62
The lifting means 63 is supported by the lower end of the lifting means 63.
3, the outer and inner discharge portions 60A, 60
The position B can be moved up and down in FIG.

The sensor 70 is of a type having a function of enabling image processing by a camera. Specifically, a light emitting element 70A arranged on the top,
And a light receiving element 70B arranged below. Each of these elements 70A, 70B has a light emitting surface 70a.
(See FIG. 3) and the light receiving surface 70b is
1 and the light receiving element 70B
The position deviation of the wafer W is detected by comparing the amount of received light with the predetermined amount of received light. Note that the sensor 70 may employ an area sensor, a line sensor, or the like. The sensor 70 may be another reflection type or transmission type sensor as long as it has the same performance.

Next, the overall operation in the first embodiment will be described.

When transferring the wafer W to the table 11, the transfer device 50 operates to pick up the wafer W stored in a cassette (not shown). Then, the transfer arm 51 enters the lower surface side of the wafer W, and sucks the central region of the wafer W at the positions of the suction holes 51B, 51B of the branch portions 51A, 51A forming the Y-shape.

The wafer W thus attracted is moved toward the table 11 by the transfer arm 51. At this time, the table 11 is maintained at a position where the inner table 11B is higher than the outer table 11A via the elevating means 16 (see a two-dot chain line in FIG. 1). At the same time, the inner table 11B is brought into a state where the pressure of the chamber 11C is reduced and the upper side air is sucked into the suction holes 11b. Then, the transfer arm 51 moves the wafer W
Is moved to a position where the inner table 11B is located between the branch portions 51A, 51A and descends while the surface of the inner table 11B holds a position slightly higher than the upper surface position of the inner table 11B. Due to this lowering, the central area of the wafer W becomes
When touching B, the central area is sucked by the inner table 11B. At this time, air is discharged from the inner discharge portion 60B of the discharge device 60, and the central region of the wafer W is strongly pressed against the surface of the inner table 11B,
The position of the wafer W is kept constant.

Next, the inner table 11B is lowered and its upper surface is lowered to a position where it coincides with the upper surface of the outer table 11A, and at the same time, the ejection device 60 is also lowered. Then, in a state where the wafer W is transferred onto the table 11, the discharge device 6
The air is also discharged from the 0 outer discharge portion 60A. Due to this discharge pressure, even if the wafer W is warped, the warp is corrected to have a planar shape,
The suction by the suction holes 11a and 11b of the outer table 11A and the inner table 11B is completed.

When the wafer W is completely attracted to the table 11 in this way, the discharge device 60 is retracted to the predetermined position, while the motor M3 of the rotating device 40 is driven to rotate the table 11. Become. Due to this rotation, the amount of light received from the light emitting element 70A toward the light receiving element 70B is sequentially captured. At this time, when the center position of the wafer W matches the preset center position, the amount of light received by the light receiving element 70B is constantly captured without change. On the other hand, when the center of the wafer W is displaced, the amount of received light changes. Therefore, by grasping the amount of this change, the amount of deviation of the center of the wafer W from the origin of the X axis and the Y axis is specified, and the X axis moving body 31 and the Y axis moving body 32 are moved by a predetermined amount based on this. What is necessary is just to drive.

After the centering of the wafer W is completed in this way, the inner table 11B rises while adsorbing the wafer W, and at the same time, the air is also blown from the inner discharge portion 60B to move the wafer W to a predetermined position. To hold.
Then, the lower surface side of the wafer W is sucked by the transfer device 50 or another transfer arm (not shown), and the wafer W is transferred onto a table of a next process device, for example, a mounter device or a dicing device in a state where the wafer W is centered. can do.

Therefore, according to the first embodiment, even if the wafer W of an extremely thin type is warped, the warp is corrected and reliable suction is realized. It is possible to rotate the sensor 7
When 0, the outer edge portion W1 is detected and the center of the wafer W can be centered while the table 11 is controlled in a predetermined manner.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, an inner table 80 and a lower discharge device 8 arranged on the outer peripheral side of the inner table 80 are provided.
1, an upper discharge device 83 disposed above the inner table 80 and the lower discharge device 81, and a lower discharge device 8
1 and the respective discharge surfaces 81S, 83S of the upper discharge device 83,
It is characterized in that an interval variable device 85 is provided, which is capable of separating and approaching each other while maintaining a gap G1 at a vertically symmetric position with respect to the wafer W.

The inner table 80 is provided with the X and Y axis moving devices 31 and 32 and the rotating device 40 shown in the first embodiment.
It is provided so as to be movable in the X and Y axis directions via an X and Y axis moving device and a rotating device (not shown) having substantially the same structure as the above, and is also provided so as to be rotatable in a horizontal plane. Further, the inner table 80 is provided with a suction hole (not shown) for sucking the wafer W on the upper surface side, and is provided so as to be able to move up and down similarly to the first embodiment.

In the present embodiment, the lower discharge device 81 is provided in an annular shape having an inner diameter at which a predetermined interval is formed between the lower discharge device 81 and the outer peripheral surface of the inner table 80. The discharge surface 81S of the lower discharge device 81 substantially corresponds to the outer peripheral region of the wafer W, and can blow gas to the lower surface of the wafer W. Here, in the illustrated example, the lower discharge device 81 having an annular outer shape is used, but the lower discharge device 81 may be divided along the outer peripheral side circumferential direction of the wafer W. However, in the case of the annular lower discharge device 81, there is an advantage that a single air supply pipe for blowing gas can be shared and a single variable interval device is sufficient.

The upper discharge device 83 is substantially the same as the discharge device 60 of the first embodiment, and substantially corresponds to the inner discharge portion 83A substantially corresponding to the inner table 80 and the lower discharge device 81. And an annular outer discharge portion 83B.

Also in the second embodiment, the wafer W can be transferred via a transfer device (not shown) at a position where the inner table 80 is higher than the lower discharge device 81. Then, the wafer W is sucked by the inner table 80, and gas is blown onto the upper and lower surfaces of the wafer W from the upper discharge device 83 and the lower discharge device 81. At this time, the upper discharge device 8 is controlled via the variable interval device 85.
3 and the lower discharge device 81 are brought close to each other, and a minimum gap G2 that does not make contact with the wafer W is taken to increase the pressure of the gas to the wafer W. Even if the wafer W is warped, this is corrected. It will be kept in a planar shape (see FIG. 5). In this state, only the inner table 80 is rotated so that the lower and upper discharge devices 81 and 83 and the wafer W
Can detect the outer edge portion W1 of the wafer W by the sensor 86 having the same configuration as in the first embodiment without contact by the gas pressure.

In the second embodiment, the inner table 8
It is not a requirement that 0 be raised with respect to the lower discharge device 81. The wafer W is positioned between the lower discharge device 81 and the upper discharge device 83 by a transfer device (not shown). By gradually blowing the gas, the distance between the upper and lower discharge devices 83 and 81 is gradually reduced, the wafer W is corrected into a planar shape and held in a non-contact state, and then the inner table 80 is raised.
After the central portion of the wafer W is sucked, it can be rotated.

Therefore, according to the second embodiment, similarly to the first embodiment, the warped wafer W is corrected to have a planar shape and rotated, so that the outer edge portion W is formed.
1 can be detected with high accuracy. Further, in the second embodiment, a transfer arm similar to that of the first embodiment can be used, and a straight arm without a branch portion can be employed.

In each of the above embodiments, the wafer W is used, but the present invention is not limited to this, and other plate-like bodies that require centering may be used. Further, the wafer W is not limited to the type that suctions the lower surface side, and may be the one that suctions the upper surface side.

In the above embodiment, the transfer arm 51
Has a branch portion 51A, 51A having a Y-shaped shape, but is not particularly limited.
The suction holes 51B may be provided on a rectangular band plate whose tip does not branch. In this case, the suction surface 80S of the inner table 80 is positioned slightly lower than the discharge surface 81S of the lower discharge device 81, and each discharge surface is held while the wafer W is being suctioned by the suction holes of the tip band plate of the transfer arm 51. 81S, 8
The inner table 80 may be raised slightly to attract the wafer W after the transfer arm 51 is retracted, with the wafer W positioned between 3S.

[0039]

As described above, according to the present invention,
A discharge device that transfers a work to a table rotatably provided in a plane and blows gas to the work, and a sensor that is disposed near an outer edge portion of the work and detects the outer edge position are provided, and the table is provided. Since the table is moved and the center of the work can be centered while referring to the detection data of the sensor when rotated, the work is pressed along the table surface by the gas blown from the discharge device. As a result, the warped work becomes substantially parallel to the surface of the table, and it is possible to reliably perform suction by the table. Therefore, the position or movement locus of the outer edge of the work when the table is rotated in this state can be detected with high accuracy, and the centering of the work can be performed with high accuracy via the moving device.

Further, the table is constituted by an outer table and an inner table, and the work is transferred via the transfer device at a position where the inner table is raised with respect to the outer table. When the transfer is required in a state where the work is not in contact with the work, the work can be transferred to the table while being supported on the lower surface of the work. Therefore, it is particularly useful when a workpiece is a wafer having a circuit surface formed on the upper surface.

Further, a discharge device is provided with an outer discharge portion and an inner discharge portion substantially corresponding to the outer table and the inner table, respectively, and the work transferred to the inner table at the raised position is used by the inner table. Gas is discharged from the inner discharge portion while being sucked and lowered, and when the inner table is lowered and the work is located on the outer and inner table surfaces, the gas is also discharged from the outer discharge portion. Even if the work is supported only by the inner table at the initial stage of the transfer, the work can be lowered while the supporting state is reliably maintained. Moreover, even if the wafer is warped, the warp can be corrected.

The work is transferred to the table with the circuit surface of the work as the upper surface, and the transfer arm constituting the transfer device has a suction hole which is divided into two ends at the tip and opened to the upper surface. Since the apparatus is configured to include the provided branch section, by incorporating the present apparatus into a semiconductor wafer manufacturing line, it is possible to improve chip processing accuracy and dramatically improve production efficiency.

Further, in the configuration in which the lower discharge device provided on the outer peripheral side of the inner table and the upper discharge device corresponding to the inner table and the lower discharge device are provided, the lower discharge device and the upper discharge device respectively blow out. Due to the pressure of the gas, even if the work is warped, the warp can be corrected to form a planar shape. In this state, the work is fixed and rotated by the suction force of the inner table, so that the outer edge portion of the work is Can be detected with high accuracy, and the centering of the work can be performed based on the detection result.

Further, in a configuration in which a variable distance device is provided between the lower discharge device and the upper discharge device, the pressure on the work is increased with the approach of the lower discharge device and the upper discharge device while the work is being sucked by the inner table. Gradually rises, and warp deformation of the work can be corrected in a non-contact state to maintain the work in a planar shape. Moreover, by keeping the discharge pressure balanced up and down, it is possible to keep the workpiece floating on a certain plane, and it is possible to expand the degree of freedom in design such as the shape of the transfer arm. Become

[Brief description of the drawings]

FIG. 1 is a schematic front view of an alignment apparatus according to a first embodiment.

FIG. 2 is a plan view of the table according to the first embodiment.

FIG. 3 is a schematic perspective view of a transfer device and a table according to the first embodiment.

FIG. 4 is a schematic front view of a main part of an alignment apparatus according to a second embodiment.

FIG. 5 is a schematic front view of a main part showing a state in which the warp of the wafer is corrected by operating the variable interval device shown in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Alignment apparatus 11 Table 11A Outer table 11B, 80 Inner table 11a, 11b Suction hole 30 Moving device 31 X-axis moving body 32 Y-axis moving body 40 Rotating device 50 Transfer device 51 Transfer arm 51A Branch 51B Suction hole 60 Discharge Apparatus 60A Outer discharge unit 60B Inner discharge unit 70, 86 Sensor 81 Lower discharge device 83 Upper discharge device 85 Variable spacing device W Wafer (work) W1 Outer edge portion of wafer

Claims (8)

[Claims] 1. An alignment apparatus for centering a substantially plate-shaped work, comprising: a table provided rotatably in a plane; and a suction hole for the work provided in at least a partial area;
A moving device for moving the table in X and Y axis directions;
A discharge device that blows gas from the opposite side of the suction hole to the work transferred onto the table, and a sensor that is disposed near an outer edge portion of the work and detects the outer edge position; An alignment device, wherein the work is centered by moving the table while referring to detection data of a sensor when the sensor is rotated. 2. The table includes an outer table and an inner table which can be moved up and down relative to the outer table, and the work is transferred at a position where the inner table is stepped with respect to the outer table. 2. The alignment apparatus according to claim 1, wherein: 3. The discharge device includes an outer discharge portion and an inner discharge portion substantially corresponding to the outer table and the inner table, respectively, and the inner table sucks a work transferred to the inner table at the raised position. Gas is discharged from the inner discharge section during the downward movement, and when the inner table is lowered and the work is located on the outer and inner table surfaces, gas is also discharged from the outer discharge section. The alignment device according to claim 2, wherein 4. The alignment apparatus according to claim 2, wherein a suction hole is provided on the inner table, and a discharge hole or a suction hole is provided on the outer table. 5. The alignment apparatus according to claim 1, wherein the work is made of a semiconductor wafer, and is transferred to the table with its circuit surface as an upper surface. 6. A transfer device for transferring a work onto the table is provided near the table, and the transfer device includes an arm having a suction hole opened to the upper surface on the distal end side. The alignment device according to claim 5, wherein the alignment device is configured. 7. An alignment apparatus for centering a substantially plate-shaped work, comprising: an inner table provided rotatably in a plane and provided with a suction hole for the work; and an outer table provided on an outer peripheral side of the inner table. A lower discharge device that blows gas on the lower surface side of the workpiece transferred onto the inner table, a moving device that moves the table in the X and Y axis directions, and a gas that moves toward the table and the lower discharge device. And a sensor disposed near the outer edge of the work to detect the position of the outer edge, wherein the table is moved while referring to data detected by the sensor when the table is rotated. An alignment apparatus, wherein the work can be centered. 8. The alignment apparatus according to claim 6, wherein the lower discharge device and the upper discharge device are connected to each other via a variable distance device.