JPH0864654A - Method and apparatus for transferring substrate - Google Patents

Abstract

PURPOSE: To obtain a convenient space saving apparatus for transferring a substrate requiring no aligning apparatus for exclusive use. CONSTITUTION: A hand 102 can support a wafer 11 having an orientation flat 11a. An arm 92 moves the hand 102 to gain access to a wafer 11 set in a cassette 13. The hand 102 has a head 132 bonded with edge sensors 132a-132c at an interval wider than the execution width of the orientation flat 11a in the direction normal to the advancing direction of the hand 10 gaining access to the wafer 11 and parallel with the surface of the wafer 11. A controller determines three edge positions of the wafer 11 based on the outputs from the edge sensors 132a-132c and the positional information of the hand 102. Assuming that at least two out of three edge positions thus determined are present on one circle, the central position 111c of the wafer 11 is determined as the center of the circle and then the hand 102 is shifted based on the central position 111c.

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 a substrate transfer method for transferring a circular substrate such as a semiconductor wafer from a transfer position such as a cassette to a processing unit or an inspection unit.

[0002]

2. Description of the Related Art Inspection of semiconductor manufacturing equipment and semiconductor wafers
Many measuring devices are equipped with an automatic transfer device for semiconductor wafers. FIG. 10 shows an example of this,
The main body 12 of the transfer device 2 is rotated to access the hand 13 to the cassette 13 on the cassette stage 3, and the wafer 11 in the cassette 13 is carried out together with the hand 22 to the outside of the cassette. Next, the wafer 11 is transferred from the hand 22 to the centering unit 4. The centering unit 4 aligns (centers) the wafer 11. Finally, the wafer 11 on the centering unit 4 is transferred to the hand 22 and taken out, and the wafer 11 on the hand 22 is transferred to the wafer stage 5. The position of the wafer 11 is adjusted by the centering unit 4 as follows.
The wafer 11 moves and displaces in the cassette 13, and in particular, the wafer 11 pops out of the cassette 13.
Is not set in the state of being accurately aligned with the processing such as the wafer stage 5 or the measuring table.

[0003]

However, in the above-mentioned device, since it is necessary to secure a space for arranging the centering unit 4, the size of the entire device is increased, which is against the request for space saving.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a space-saving and simple substrate transfer apparatus and a method for transferring a substrate, which does not require a device for exclusive use of positioning such as a centering unit 4 which has conventionally been required.

[0005]

In order to solve the above problems, a substrate transfer apparatus according to a first aspect of the present invention has a supporting means capable of supporting a circular substrate having a notch and a supporting means which is moved to a transfer position. The moving means for accessing the placed circular substrate and the supporting means side with a space wider than the effective width of the notch in the lateral direction perpendicular to the forward direction of the supporting means for accessing the circular substrate and parallel to the surface of the circular substrate. Based on the three fixed edge sensors, the outputs of the three edge sensors, and the position information of the supporting means, the three edge positions of the circular substrate are determined, and at least two of the determined three edge positions are determined. Assuming that one is a point on the circumference, the center position of the circular substrate is calculated by geometrical coordinate calculation as the center point of this circumference, and the supporting means is moved based on the calculated center position of the circular substrate. And control means for.

Further, in the substrate transfer apparatus according to the second aspect, the control means sets the center position of the circular substrate to the radius of the circular substrate with a line segment between any two of the three edge positions as the base. It is characterized in that it is calculated as the vertices of an isosceles triangle having both sides of corresponding length.

Further, in the substrate transfer apparatus according to a third aspect of the present invention, the control means first calculates 3 based on the geometrical coordinate calculation assuming that any two of the three edge positions are points on the circumference. When all the center points do not match, the supporting means is moved again in parallel with the forward direction at a predetermined interval in the lateral direction to redetermine the three edge positions of the circular substrate, and the three edge positions of the determined three edge positions are determined. By selecting one of the three center points calculated again based on the geometrical coordinate calculation assuming that any two of them are points on the circumference, whichever one of the first three calculated center points matches The center position of the circular substrate is calculated.

Further, in the substrate transfer method according to a fourth aspect of the present invention, the step of moving the supporting means capable of supporting the circular substrate having the notch to access the circular substrate placed at the transfer position,
Outputs of three edge sensors fixed to the support means at intervals wider than the effective width of the notch in the lateral direction perpendicular to the advance direction of the support means for accessing the circular substrate and parallel to the surface of the circular substrate. Determining the three edge positions of the circular substrate on the basis of the position information of the supporting means, and the center of this circumference when at least two of the three determined edge positions are points on the circumference. The method includes a step of calculating the center position of the circular substrate as a point by geometrical coordinate calculation, and a step of moving the supporting means based on the calculated center position of the circular substrate.

[0009]

In the substrate transfer apparatus according to the first aspect of the present invention, the three edge sensors are fixedly provided on the support means side with a width wider than the effective width of the cutout in the lateral direction, so that the cutout position of the circular substrate is not affected. Of course, the at least two edge positions obtained correspond to points on the circumference without cutouts. Therefore, the control means can accurately calculate the center position of the circular substrate based on the at least two edge positions corresponding to points on the circumference having no notch, and based on this, the support means is moved to move the circular shape. The support means can be accurately aligned with the substrate.

Further, in the substrate transfer apparatus according to the present invention, the control means sets the base line to a line segment between any two of the three edge positions, and has both sides having a length corresponding to the radius of the circular substrate. Since the center position of the circular substrate is calculated as the apex of the isosceles triangle having, the center position of the circular substrate can be specified easily and reliably.

Further, in the substrate transfer apparatus according to the third aspect of the present invention, the control means moves the supporting means again in parallel with the forward direction at a predetermined interval in the lateral direction when the three initially calculated center points do not coincide. Then, the center position of the circular substrate is calculated by selecting one of the three calculated center points that matches any of the three calculated center points first. Therefore, the center position of the circular substrate is calculated based on only the edge position not cut. The center position of the circular substrate can be accurately specified.

Further, in the substrate transfer method according to the present invention, since the three edge sensors are fixedly provided on the support means side at intervals wider than the effective width of the notch in the lateral direction, the position of the notch of the circular substrate is fixed. Obtained at least 2
The one edge position corresponds to a point on the circumference with no notches. Therefore, it is possible to accurately specify the center position of the circular substrate based on at least two edge positions corresponding to points on the circumference having no notch, and based on this, the supporting means can be moved to move with respect to the circular substrate. The support means can be accurately aligned.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a substrate transfer device of an embodiment applicable to a wafer surface evaluation device, a film thickness meter, a spinner, etc., and FIG. 1 (a) is a plan view of the substrate transfer device. FIG. 1B is a view of the substrate transfer device viewed from the arrow X. The substrate transfer device 52 includes a base 62 fixed to the floor, a moving body 72 that reciprocates in the horizontal AB direction on the base 62, and a main body 82 fixed on the moving body 72. This body 82
The arm 92 includes an expandable and contractable three member whose one end is fixed to the side, a hand 102 fixed to the tip of the arm 92, and a control device 112 for controlling these operations. Although illustration of the cassette corresponding to the wafer transfer position and the wafer stage such as the wafer surface evaluation device is omitted, the base 6 of FIG.
It is arranged around 2.

The moving body 72 moves on a rail 62a formed on the base 62 side along the rail 62a. The movement is performed by appropriately rotating a ball screw 62b provided on the base 62 with a motor 62c.

The arm 92 is for moving the hand 102 provided at its tip to a desired position. The drive source in the main body 82 and a mechanism in the arm 92 move the hand 102 in the horizontal CD direction. Reciprocate or swivel in a horizontal plane. Also, this arm 92 is
The drive source in 2 causes vertical E with hand 102.
Reciprocates in the F direction.

The hand 102 is for supporting a wafer (not shown), and is provided with a vacuum chuck 122 for sucking the wafer for more reliable support. Also, hand 1
A head 132 is formed at the base of 02, and three edge sensors 132a and 132b for detecting the edge of the wafer are provided.
132c is built in.

The control device 112 includes a moving body 72 and an arm 9.
2 is controlled to move the hand 102 to an arbitrary position, and an encoder or the like is used to move the hand 102.
Monitor the location information of. By monitoring the position information of the hand 102 in this manner, it becomes possible to reliably transfer the wafer accommodated in the cassette (not shown) to the wafer stage or the like. At this time, as described in detail below, the edge sensors 132a, 132b, 132
The center position of the wafer is calculated based on the edge detection result of c, and is used for aligning the hand 102 with the wafer.

2 and 3 are views showing the structure of the hand 102 and the state of access to the circular wafer 11 accommodated in the cassette 13. As shown in FIG.

As shown in FIG. 2, three edge sensors 1 are provided.
32a, 132b, 132c are in the AB direction (hand 102
Is perpendicular to the CD direction, which is the forward direction of (1), and is evenly spaced in the horizontal direction parallel to the surface of the wafer 11), and the spacing is set wider than the effective width of the orientation flat 11a. In addition,
The effective width of the orientation flat 11a is the center edge sensor 13
2b and either of the edge sensors 132a, 132
The minimum sensor interval required to prevent simultaneous detection of the orientation flat 11a with c. The effective width of the orientation flat 11a will be described later in detail.

As shown in FIG. 3, three edge sensors 1
Reference numerals 32a, 132b, and 132c each include a pair of upper and lower rods, one end of each rod projects from the head 132, and a projecting portion 142 and a light receiving portion 152 are formed to face each other at the tips of the projecting rods. The light projecting section 142 and the light receiving section 152 are connected to an electronic circuit (not shown) having a light emitting / light detecting function via an optical fiber extending through the rod toward the main body 82 side in FIG.
The output of this electronic circuit is processed by the controller 112 of FIG. Returning to FIG. 3 again, the light projecting unit 142 and the light receiving unit 15
2 inserts the hand 102 into the cassette 13 from above and below the edge of the wafer 11 housed in the cassette 13. Therefore, the inspection light from the light projecting portion 142 is blocked by the edge of the wafer 11. Therefore, while monitoring the position of the hand 102, the hand 102 is moved forward or backward in the CD direction, and the intensity change of the inspection light detected by the light receiving unit 152 is determined to determine the position of the edge of the wafer 11 (hereinafter referred to as edge). Position) can be determined.

FIG. 4 is a flow chart for explaining the outline of the transfer operation of the wafer 11 by the substrate transfer apparatus of the embodiment.

First, the hand 102 is moved forward from the standby position as shown in FIG. 1A and moved to the cassette 13 side in FIG. 2, the wafer 11 stored in the cassette 13 is accessed and the wafer 11 is taken. (Step S1).

Next, the hand 102 is aligned with the wafer 11 (step S2). That is, when the three edge positions of the wafer 11 are determined based on the edge detection outputs of the edge sensors 132a, 132b, and 132c, and two of the determined three edge positions are assumed to be points on the circumference. The center position of the wafer 11 (hereinafter, wafer center) is calculated by geometrical coordinate calculation as the center point of this circumference, and the hand 102 is placed so that the calculated wafer center is located at the center of the vacuum chuck 122 of the hand 102.
To move. It should be noted that three wafer centers are calculated from the obtained three edge positions, but if these three wafer centers do not match, any of the obtained three edge positions is applied to the orientation flat 11a. It is determined that the hand 102 is slightly moved in the lateral direction (AB direction in FIG. 2), the hand 102 is moved forward or backward in the CD direction again, and the wafer center is again measured from the obtained three edge positions. To calculate. Of the recalculated wafer centers, the one that matches the initially calculated wafer center is set as the actual center position of the wafer 11 and the hand 102 is aligned.

Next, the wafer 11 is transferred from the cassette 13 to the hand 102 (step S3). That is, the vacuum suction of the vacuum chuck 122 of the hand 102 is turned on (O
N) and raises the hand 102 until the upper surface of the hand 102 contacts the back surface of the wafer 11 to transfer the wafer 11 to the hand 102.

Next, the wafer 11 is moved to the wafer stage (not shown) side together with the hand 102 (step S4). That is, the hand 102 is retracted to take out the wafer 11 from the cassette 13, and the hand 102 is moved (turned or moved forward) to convey the wafer 11 to the wafer stage side.

Next, the wafer 11 is transferred from the hand 102 to the wafer stage (step S5). That is, the hand 102 is lowered to a height where the distance between the back surface of the wafer 11 and the upper surface of the wafer stage is several mm (1 to 5 mm).
Then, the vacuum suction of the hand 102 is turned off,
The vacuum suction of the wafer stage is turned on. The hand 102 is further lowered and the wafer 11 is transferred to the wafer stage.

Finally, the hand 102 is retracted and moved to the standby position (step S6). By the above-described flow, the wafer 11 can be mounted on the wafer stage while being centered.

FIGS. 5 and 6 are flow charts for explaining in detail the positioning of the hand 102 in step S2 of FIG.

First, the hand 102 is inserted into the cassette 13 accommodating the wafer 11 (step S10).
2). Three edge sensors 132a, 132b, 132
Based on each output of c and the position information of the hand 102, the three edge positions of the wafer 11 are determined (step S11).
2). Arbitrary two of the determined three edge positions are set as a set, and the wafer center is calculated as the center point of the circumference when these are assumed to be points on the circumference (step S).
122). Specifically, any 2 of the 3 edge positions
The line segment between the two edge positions is the bottom 111a and the wafer 11
The wafer center is calculated as the apex 111c of an isosceles triangle having both sides 111b of the radius of the. At this time, since there are three ways to select the edge position, the number of calculated vertices 111c is three, but when the edge position does not fall on the orientation flat 11a as shown in FIG. 2, these almost match. Next, the calculated three vertices 1
It is determined whether all 11c match (step S13).
2). If all three vertices 111c match, it is determined that the obtained edge position is not on the orientation flat 11a, and the mounting center of the hand 102 (the center of the vacuum chuck 122) is set at the wafer center of the obtained vertex 111c. It is moved (step S142).

On the other hand, if it is determined in step S132 that the three vertices (which are located at the vertex 111c in the case of FIG. 2) do not match, it is determined that the obtained edge position depends on the orientation flat 11a. Judge and hand 102
Is moved backward (step S152). Hand 102
Is shifted in the horizontal direction AB (step S162). The amount of shift is determined by the edge sensors 132a and 132c at both ends of the wafer 1
There is no particular limitation as long as an edge of 1 can be detected.
If it is shifted too much in the direction, it becomes difficult to accurately detect the edge position. The hand 102 is reinserted into the cassette 13 (step S172). The edge positions of the three points on the wafer 11 are determined again (step S182). The vertices of the isosceles triangle whose bases are any two of the three determined edge positions (the positions are approximately at the vertices 111c in FIG. 2) are calculated in the same manner as in step S122 (step S122). S192). A total of 6 vertices including the 3 vertices calculated first and the 3 vertices calculated this time are compared (step S202). As will be described later in detail, since at least two of these six vertices are obtained from edge positions other than the orientation flat 11a, they eventually coincide with each other and correspond to the wafer center (step S212). The mounting center of the hand 102 is moved to the wafer center corresponding to these two coincident vertices (step S222).

FIG. 7 shows a case where the orientation flat is detected as an edge position, and is a diagram for explaining the processing of step S132 (see FIG. 5) corresponding to the first edge position determination. Of the three edge positions, for example, 2 on the upper side of the drawing
An isosceles triangle having a base 111a between two edge positions e1 and e2 and both sides 111b having a radius length (two-dot chain line)
Apex 111c 'and two edge positions e on the lower side of the drawing
The base 111a is between 2 and e3 and both sides 111 of the radius length
It does not match the apex 111c of the isosceles triangle (solid line) having b. That is, the vertex 1 of the isosceles triangle of the two-dot chain line
Since 11c 'is obtained from the edge position e1 of the orientation flat 11a, it does not coincide with the wafer center. Although not shown, edge positions e1 and e3
The vertices of an isosceles triangle having a space between them as bases and both sides having a radius length do not coincide with the wafer center, as described above.
On the other hand, the apex 111c of the isosceles triangle of the solid line is obtained from the edge positions e2 and e3 which are not on the orientation flat 11a, and therefore coincides with the wafer center. However,
At this step S132, which vertex 111
It cannot be determined whether c ', 111c is the wafer center.

FIG. 8 shows a case where the orientation flat is detected as an edge position, and is a diagram for explaining the processing of step S202 (see FIG. 6) corresponding to the determination of the edge position again. In this case, the edge sensors 132a, 1a
32b and 132c are distances S from the position shown in FIG.
It is in the position of the solid line, which is shifted horizontally. Therefore, in the determination of the edge position again, the lateral position correction corresponding to this interval S is performed.

Of the three edge positions, for example, an apex 111c "of an isosceles triangle (two-dot chain line) having a base 111a between two edge positions e1 'and e2' on the upper side of the drawing and having both sides 111b having a radius length. And an apex 111 of an isosceles triangle (solid line) having a base 111a between two edge positions e2 'and e3' on the lower side of the drawing and having both sides 111b having a radius length.
Does not match c. That is, since the apex 111c ″ of the isosceles triangle of the two-dot chain line is obtained from the edge position e1 ′ on the orientation flat 11a, it does not coincide with the wafer center. The vertices of an isosceles triangle that has both sides of the radius length with the base between “and e3” do not match the wafer center, while the vertices 111c of the solid isosceles triangle are edge positions that are not on the orientation flat 11a. Since it is obtained from e2 'and e3', it coincides with the wafer center.
The vertex 111c ″ does not match the vertex 111c ′ in FIG. 7. The corresponding edge positions e1 and e1 ′ are
This is because the distance from the circumference when the orientation flat 11a is not present is different.

As is apparent from the above, the vertex 111c among the vertices 111c, 111c ', and 111c "obtained by the vertex detection based on the edge position determination as shown in FIGS.
Match and are detected again (see step S212 above). Therefore, it can be seen that this vertex 111c becomes the wafer center.

FIG. 9 illustrates the effective width of the orientation flat 11a. Three edge sensors 132a, 1
32b and 132c are arranged at a distance P wider than the effective width OF of the orientation flat 11a, which is the edge sensor 132b at the center and one of the edge sensors 132 at both ends.
This is to prevent the orientation flat 11a from being detected simultaneously with a and 132c. Effective width OF of this orientation flat 11a
As shown, the center edge sensor 132b detects one end of the orientation flat 11a.
hand 102 in the case where a is placed
Corresponds to the width of the orientation flat 11a in the horizontal direction perpendicular to the traveling direction of the.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments.
For example, the same measurement as described above can be performed on a wafer having a notch instead of the orientation flat 11a.
The position of the hand 102 can be adjusted for such a wafer.

Further, in the above-mentioned embodiment, the hand 102 is configured to have the vacuum chuck 122 to support the back surface of the substrate. However, the present invention is not limited to this. For example, a supporting member for supporting the peripheral edge of the substrate at a plurality of points is provided, It can also be configured to support and convey the peripheral edge of the.

[0038]

As described above, according to the apparatus of claim 1, the three edge sensors are fixedly provided on the support means side at intervals wider than the effective width of the notch in the lateral direction. Regardless of the position of the notch in the circular substrate, the at least two edge positions obtained correspond to points on the circumference without a notch. Therefore, the control means can accurately calculate the center position of the circular substrate based on the at least two edge positions corresponding to points on the circumference having no notch, and based on this, the support means is moved to move the circular shape. The support means can be accurately aligned with the substrate. Therefore, a special positioning mechanism such as a centering unit is not required, the cost of the device can be reduced, and the size of the device can be reduced, which saves space and improves reliability.

According to the second aspect of the present invention, the control means sets the base line to the line segment between any two of the three edge positions, and has both sides having a length corresponding to the radius of the circular substrate. Since the center position of the circular substrate is calculated as the apex of the isosceles triangle having, the center position of the circular substrate can be specified easily and reliably.

According to the third aspect of the invention, the control means moves the supporting means again in parallel with the forward direction at a predetermined interval in the lateral direction when the three initially calculated center points do not coincide. Then, the center position of the circular substrate is calculated by selecting one of the three calculated center points that matches any of the three calculated first center points.
The center position of the circular substrate can be accurately specified based only on the edge position that is not cut out.

Further, according to the method of claim 4, since the three edge sensors are fixedly provided on the support means side at intervals larger than the effective width of the notch in the lateral direction, the position of the notch of the circular substrate is fixed. Regardless, the at least two edge positions obtained correspond to points on the circumference without a notch. Therefore, it is possible to accurately specify the center position of the circular substrate based on at least two edge positions corresponding to points on the circumference having no notch, and based on this, the supporting means can be moved to move with respect to the circular substrate. The support means can be accurately aligned.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a substrate transfer device according to an embodiment.

FIG. 2 is a plan view showing a main part of the substrate transfer device of FIG.

3 is a side view showing a main part of the substrate transfer device of FIG. 1. FIG.

FIG. 4 is a flowchart illustrating an operation of the substrate transfer device shown in FIG.

5 is a flowchart illustrating a part of the flowchart of FIG. 4 in detail.

FIG. 6 is a flowchart illustrating a part of the flowchart of FIG. 4 in detail.

FIG. 7 is a diagram illustrating a specific operation executed by the flowcharts of FIGS. 5 and 6;

FIG. 8 is a diagram illustrating a specific operation executed by the flowcharts of FIGS. 5 and 6;

FIG. 9 is a diagram illustrating an effective width of orientation flat.

FIG. 10 is a diagram illustrating a conventional device.

[Explanation of symbols]

 11 Wafers 13 Cassettes 92 Hands 102 Arms 112 Control Devices 132 Heads 132a to 132c Edge Sensors

Claims (4)

[Claims] 1. A supporting means capable of supporting a circular substrate having a notch, a moving means for moving the supporting means to access the circular substrate placed at a transfer position, and a supporting means for accessing the circular substrate. Three edge sensors fixed to the supporting means side at intervals wider than the effective width of the notch in the lateral direction perpendicular to the forward direction of the circular substrate and parallel to the surface of the circular substrate; and the three edges. When three edge positions of the circular substrate are determined based on each output of the sensor and the position information of the supporting means, and at least two of the determined three edge positions are assumed to be points on the circumference, Control means for calculating the center position of the circular substrate as a center point of the circumference by geometrical coordinate calculation and moving the supporting means based on the calculated center position of the circular substrate. Substrate transfer device. 2. The control means sets a center position of the circular substrate to a line segment between any two edge positions of the three edge positions as a base, and has a length corresponding to a radius of the circular substrate. The substrate transfer apparatus according to claim 1, wherein the calculation is performed as the vertices of an isosceles triangle having both sides. 3. The control means does not match all three center points initially calculated based on geometrical coordinate calculation assuming that any two of the three edge positions are points on the circumference. In this case, the supporting means is moved again at a predetermined interval in the lateral direction in parallel with the traveling direction to re-determine the three edge positions of the circular substrate, and the determined three positions are determined.
Of the three center points calculated again based on the geometrical coordinate calculation assuming that any two of the two edge positions are points on the circumference, the one that matches any of the first three calculated center points The substrate transfer apparatus according to claim 1, wherein the center position of the circular substrate is calculated by selecting the center position. 4. A step of moving a supporting means capable of supporting a circular substrate having a notch to access the circular substrate placed at a transfer position, and a step of advancing the supporting means for accessing the circular substrate perpendicularly to the circular substrate. And based on the output of each of the three edge sensors fixedly provided on the supporting means side at a distance wider than the effective width of the notch in the lateral direction parallel to the surface of the circular substrate and the position information of the supporting means. And determining the three edge positions of the circular substrate, and the center of the circular substrate as the center point of the circumference when at least two of the determined three edge positions are assumed to be points on the circumference. A substrate transfer method comprising: a step of calculating a position by geometrical coordinate calculation; and a step of moving the supporting means based on the calculated center position of the circular substrate.