JPH07302828A - Substrate transfer device - Google Patents

Abstract

PURPOSE:To make it possible to position a substrate without damaging a wafer or generating dust. CONSTITUTION:Position of a wafer 2 is detected while holding the wafer 2 with an arm 8 while carrying the wafer 2, and relative movement is made between the arm 8 and a center table 7 based on the results of the detection so as to hand over the wafer 2 to a predetermined position of a center table 7 when handing over the wafer 2 from the arm 8 to the center table 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate transfer device for a wafer or the like in a semiconductor manufacturing device or a measurement / inspection device, and more particularly to positioning of a substrate.

[0002]

2. Description of the Related Art A conventional wafer positioning method in a substrate transfer apparatus is shown in FIG. 2 after a wafer is placed near the center of an OF (orientation flat) detecting rotary table and the rotary table is rotated to detect the OF position. As described above, a method is widely used in which the wafer is slid by the roller pins B2 and the wafer is pressed against the reference roller pins B1 provided two in the OF portion of the wafer and one in the circumferential portion to complete the positioning. .

[0003]

However, according to the conventional method, there is a possibility that the wafer may be damaged due to the lower surface of the wafer being slid or the roller pins being pressed, and dust may be generated. There is. Therefore, it is an object of the present invention to develop a substrate transfer device that can position a wafer without damaging the wafer, generating dust, and the like.

[0004]

In order to solve the above problems, a substrate transfer apparatus of the present invention has a holding member for holding a substrate, and the holding member is held by moving the holding member. A transport unit that transports the substrate, a table that receives and supports the substrate from the transport unit, and a table that is provided at a predetermined position in the middle of the substrate transport path of the transport unit and that holds the substrate in the holding member. Based on the detection result of the detection unit, the table and the holding member are relatively positioned so that the substrate is transferred to a predetermined position on the table when the substrate is transferred from the transfer unit to the table. And a moving means for moving the same.

[0005]

The substrate transfer apparatus of the present invention detects the position of the substrate while it is being held by the holding member during the transfer of the substrate such as a wafer, and when the substrate is transferred from the holding member to the table, it is held based on the detection result. Since the substrate is passed to the predetermined position on the table by moving the member and the table relative to each other, the substrate can be positioned without damaging the substrate or generating dust.

[0006]

FIG. 1 is a perspective view of a non-contact wafer positioning apparatus according to an embodiment of the present invention, and FIGS. 3A, 3B and 3C are views taken in the direction of arrow A in FIG. (Proceeding from (a) to (c)) is shown together with XY coordinates. Further, FIG. 5 is an example of a control device used together with FIG.

The wafer 2 in the carrier 1 has an ideal center C
In the case of 3, the sheet is conveyed to the ideal center C4 without correction in the XY directions. However, setting up a carrier,
Since the position of the wafer in the carrier 1 varies, the wafer center is actually located at a position such as C1 which is eccentric with respect to C3 by ΔX and ΔY. In this case, the eccentricity amounts ΔX and ΔY from C3 to C1 are measured, and the wafer transferred from C1 to C2 is corrected and moved to C4. The wafer sent to C4 rotates around C4 without being eccentric and the OF direction is determined by the OF detection optical systems 9 and 10. Therefore, the wafer positioning is completed without contacting the wafer surface and the outer periphery. .

A detailed description of embodiments of the present invention will be given below. The arm 8 which is movable in the XY directions and whose movement amount in the XY directions is monitored by a coordinate detector (not shown) is driven by a driving device (not shown) to enter into the wafer carrier 1 on the up-and-down moving table 3 to move the wafer. Is vacuum-sucked and the wafer is transferred from the C1 position to the C2 position. In the middle of this, a pair of photocouplers 4A, 4B and 5A for detecting the amount of positional deviation
.5B optical axes 6A and 6B are in the wafer transfer direction (Y direction)
When the edges of the wafer block the optical axes 6A and 6B, the Y coordinate of the arm 8 at that time is stored in response to the signals from the photoreceivers 4B and 5B of the photocoupler. In addition, photo couplers 4A ・ 4B, 5A ・ 5
The B optical system stabilizes the position where the light is blocked, so that the projector 4
The light fluxes emitted by A and 5A are condensed near the passage of the wafer 2 and can be detected by the light receivers 4B and 5B.

Since the distance between the two optical axes 6A and 6B in the X direction has been measured in advance, the directions of 6A-6B are the X axis and C3.
Coordinates A1 to A4 corresponding to the outer diameter of the wafer are determined in a coordinate system in which the direction of −C4 is the Y axis. These coordinates A1 to A4
From the above, the center position of the wafer is calculated by the method described later, and the correction amounts (deviation amounts ΔX, ΔY) are calculated. At the wafer transfer position shown in FIG. 1, the arm 8 is moved by the correction amount obtained above to correct the wafer center position from C2 to C4.

The center table 7 is vertically movable,
Furthermore, the structure is such that it can rotate around C4.
After moving the arm 8 so as to correctively move the wafer 2 to the C4 position, the center table 7 is raised, and the wafer 2 is received and adsorbed with the center of the center table 7 and the center of the wafer 2 aligned. Next center table 7
Is rotated and the OF detection is performed by the optical system 11 having the light projector 9 and the light receiver 10 to accurately match the OF direction of the wafer 2. With such a procedure, the XY direction and the rotation direction of the wafer 2 can be aligned without contact.

Next, the control device of the apparatus shown in FIG. 1 will be described with reference to FIG. When the wafer 2 passes through the optical axes of the photo couplers 4A, 4B, 5A, 5B, the light receivers 4B, 5
When the output signal of B changes, the detection member 5
0 and 51 generate a pulse, and this pulse is input to the arithmetic means 60 composed of a microcomputer or the like. On the other hand, the Y-coordinate from the Y-direction coordinate detector 56 that monitors the Y-coordinate of the arm 8 is also input to the calculation means 60, and when the first pulse is input from the detection member 50, the Y-direction coordinate detection is performed. The Y coordinate of the container 56 is stored in the internal memory 52. Let this value be Y ₁ . When the second pulse is input from the detection member 51, the Y-direction coordinate detector 56
The Y coordinate of is stored in the internal memory 53. This value is Y ₂
And When one pulse is input from the detection member 51, the Y coordinate of the Y coordinate detector 56 is stored in the internal memory 54. This value is Y ₃ . Further, when the second pulse is input from the detection member 51, the Y coordinate of the Y coordinate detector 56 is stored in the internal memory 55. Let this value be Y ₄ . The calculating means 60 calculates the shift amounts ΔX and ΔY of the center position from the Y coordinates Y _{1 to} Y ₄ of the internal memories 52 to 55 and the data of the memory 61, and calculates these values Δ.
X and ΔY are input to the X-direction moving means 62 and the Y-direction moving means 63 of the arm 8. As a result, the alignment is performed so that the center of the wafer 2 coincides with the center of the center table 7.

Even if the arm 8 is monitored only in the Y direction and the center table 7 is movable in the X direction instead of monitoring the arm 8 in the XY directions, the deviation amounts ΔX and ΔY are corrected. be able to. Next, an example of the method of calculating the wafer center by the calculation means 60 will be described. FIG. 4 shows the XY coordinates in FIG. 3 and the coordinates Y1 to Y4 read when the wafer is scanned. If the OF portion of the wafer is not included in any of Y1 to Y4, 3 points are selected from 4 points of Y1 to Y4.
By substituting the points into the circle equation, the wafer center O '
Is required.

That is, three points (x ₁ , y ₁ ) (x ₁ , y
₂ ) The equation of the circle passing through (x ₃ , y ₃ ) is

[0014]

Therefore, if these are solved for a, b, and r,

[0015]

[Equation 2] Therefore, the combination of selecting 3 points from 4 points is substituted into the above equation, and (a, b) when the radius r becomes the maximum value is set as the center of the wafer. Also, consider a case where the OF portion of the wafer exists on the detection optical axis and one of the four points such as point Y5 in FIG. 4 does not exist on the circumference of the wafer.

In this case, 4 of Y1, Y2, Y3 and Y5
Make 4 combinations from the combination of selecting 3 points.
The coordinates of each of the three points in each set are substituted into the circle equation to calculate the radius and center coordinates of the circle. Here, since Y5 is included in three of the four circles, the radius of the circle becomes small. Therefore, if a circle with the largest radius is selected from the four circles, the center coordinates thereof will be the center coordinates O'of the wafer.

In the above description, the two photocouplers are provided in the X direction which is orthogonal to the wafer carrying direction (Y direction), but the optical axes of the two photocouplers must be arranged in parallel in the wafer carrying direction. Good. Further, by providing two or more photo couplers, it is possible to deal with the case where the wafer has a plurality of notches.

[0018]

As described above, according to the present invention, the substrate can be positioned at a predetermined position on the table without damaging the substrate or generating dust.

[Brief description of drawings]

FIG. 1 is a perspective view of a wafer positioning device according to the present invention.

FIG. 2 is a schematic view of a main part of a conventional mechanical wafer positioning device.

FIG. 3 is a view corresponding to the arrow A view of FIG. 1 showing the movement process of the wafer in (a), (b) and (c) for explaining the operation of the embodiment of FIG.

FIG. 4 is a diagram for explaining an example of displacement amount measurement.

5 is a block diagram of a controller for use with the embodiment of FIG.

[Explanation of sign]

 2 Wafers 4A, 5A Light emitters 4B, 5B Light receivers 6A, 6B Optical axis 8 Arms 50, 51 Detection members 52, 53, 54, 55 Internal memory 56 Y-direction coordinate detector 60 Computing means 61 Memory

Claims (3)

[Claims] 1. A carrying means for holding a substrate, carrying means for carrying the substrate held by the holding member by moving the holding member, and a table for receiving and supporting the board from the carrying means. And provided at a predetermined position in the middle of the substrate transfer path of the transfer means,
Detection means for detecting the position of the substrate while holding the substrate on the holding member; and detection of the detection means so that the substrate is delivered to a predetermined position of the table when the substrate is delivered from the transport means to the table. A substrate transfer device comprising: a moving unit that relatively moves the table and the holding member based on a result. 2. The detecting means includes photoelectric detecting means for photoelectrically detecting an edge of a substrate held by the holding member, and measuring means for measuring a moving position of the holding member. The substrate transfer device according to claim 1. 3. The table is a rotary table, and the moving means moves the holding member and the rotary table so that a center of the substrate held by the holding member and a center of rotation of the rotary table coincide with each other. The substrate transfer device according to claim 1 or 2, wherein the substrate transfer device is moved relatively.