JPH0590390A - Positioning device for wafer - Google Patents

Abstract

PURPOSE:To provide a positioning device for wafer which can improve throughput by reducing the number of resetting a rotary reference position of a wafer holder and improve yield by contraction of a recess of the holder in the device for positioning the wafer at a predetermined position on a stage by using an orientation flat part. CONSTITUTION:A first reference member 10, a second reference member 11 and pressing means 12, 13 are provided integrally with a wafer holder 2, integrally rotated when the holder 2 is rotated by the operations of rotating means 4-9 thereby to eliminate necessity of returning the rotation of the holder 2 to a reference position when the wafer is replaced and to narrow the width of a recess 2c by the amount corresponding to the rotary stroke of the holder 2 so as to be convenient for flattening the wafer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer positioning device used in a semiconductor exposure apparatus or the like.

[0002]

2. Description of the Related Art In a semiconductor exposure apparatus for transferring an original pattern such as a mask and a reticle onto a wafer, a plurality of different original patterns are usually superposed on a wafer by a plurality of exposure steps in order to manufacture a semiconductor device. Therefore, it is necessary to accurately position the wafer with respect to the original plate in order to accurately match the positional relationship of the transfer pattern in each process. The final positioning of the wafer is performed by detecting an alignment mark previously attached on the wafer by using an alignment device using image recognition or other optical means mounted on the exposure device. Since the alignment mark detection range of the alignment device is limited, a linear cutout (hereinafter referred to as an orientation flat) provided in a part of the wafer peripheral edge is used as a pre-stage to detect the outline of the wafer. It is necessary to perform positioning and bring the alignment mark into the detection range of the alignment device. Also, like a reduction projection exposure device that transfers a fine pattern on a reticle onto a wafer via a projection lens,
When the exposure area for one exposure is limited, a so-called step-and-repeat exposure method is used in which a wafer stage on which a wafer is mounted is repeatedly moved and exposed to transfer a plurality of patterns onto the wafer. .. In addition, the orientation flat is set to one of the wafer stage feed directions in order to match the crystal growth direction of the wafer with the pattern area on the original plate and to measure the orthogonality of the two feed directions of the wafer stage from the transfer pattern. It has become desirable to be able to position the wafer in two directions, one oriented parallel and the other rotated by 90 degrees.

The rough positioning of the wafer using the orientation flat has been performed by transferring the wafer positioned by the positioning device provided outside the wafer stage onto the wafer stage by using the transfer device. As the required accuracy of positioning becomes stricter,
In order to remove an error caused by delivery or the like during transportation, a method has been adopted in which a positioning device is also provided on the wafer stage and the transported wafer is repositioned on the wafer stage. A conventional example of the positioning device on the wafer stage will be described below with reference to the drawings.

FIG. 3 is a plan view of a conventional wafer positioning device. In FIG. 3, the chain double-dashed line shows the outer shape of the positioned wafer. A wafer stage 51 is movable in the x and y directions in the figure. 52 is a wafer holder,
The wafer stage 51 is rotatably installed about a point O ', and the wafer can be vacuum-sucked and held, and the suction of the wafer can be released by blowing air or a gas such as nitrogen. In addition, the wafer holder 52
In the three recesses 52a, 52b, so that one orientation flat and two circumferential portions of the wafer protrude.
52c is provided. Reference numeral 53 indicates a center-up function, which enables vertical movement and vacuum suction / release of the wafer. 54 is a lever attached to the wafer holder 52,
55 is a cam follower. 56 is a wedge member, 57 is a nut, 58 is a feed screw, and 59 is a motor. The wedge member 56 and the nut 57 are integrally attached. The wafer holder 52 is rotated by rotating the motor 59 while the cam follower 55 is pressed against the wedge member 56 by an elastic means (not shown). The stroke of the wafer holder 52 in the rotating direction is at most 1 to 2 degrees. Reference numeral 60 denotes a first reference member, which has a first contact portion 60a that contacts the circumferential portion of the wafer. Reference numeral 61 is a linear guide, and 62 is an air cylinder. First
The reference member 60 has a position where the first contact portion 60a comes into contact with the circumferential portion of the wafer by the action of the air cylinder 62,
The first contact portion 60a is movable between the first contact portion 60a and the position away from the wafer. FIG. 3 shows the former position. Reference numeral 63 is a second reference member, which is the second contact portions 63a and 6a that contact the orientation flat of the wafer.
3b. Reference numeral 64 is a linear guide, and 65 is an air cylinder. The second reference member 63 is located between the position where the second contact portions 63a and 63b contact the orientation flat and the position where the second contact portions 63a and 63b move away from the wafer by the action of the air cylinder 65. You can move with. FIG. 3 shows the former position. 66 is a pressing member, 67 is an air cylinder, and the pressing member 66 can press the wafer in the direction of the center O ′ while contacting the circumferential portion of the wafer by the action of the air cylinder 67.

The operation of the wafer positioning apparatus configured as described above will be described below. First,
The wafer, which is positioned with a predetermined accuracy by a positioning device (not shown) provided outside the wafer stage 51, is carried onto the wafer holder 52 by a carrying means (not shown). At this point, the center-up 53 rises to adsorb the back surface of the wafer. When the transfer means is retracted, the center-up 53 is lowered, and the wafer is placed on the wafer holder 52 between the first contact portion 60a and the second contact portions 63a and 63b and the pressing member 66. After that, the wafer holder 52 blows out gas and the back surface of the wafer and the wafer holder 5
The friction between the second mounting surface and the mounting surface is reduced, and in this state, the air cylinder 67 operates and the pressing member 66 presses the wafer toward the point O ′. At this time, the first reference member 60 is in a position where the first contact portion 60a contacts the circumferential portion of the wafer,
The reference member 63 is located at a position where the second contact portions 63a and 63b contact the orientation flat. The wafer pressed by the pressing member 66 has a first contact portion 63a and a second contact portion 6 as indicated by a two-dot chain line in FIG.
It is positioned at a position determined by three points, 3a and 63b. After this positioning, the wafer holder 52 holds the wafer by vacuum suction. Since the back surface of the vacuum-adsorbed wafer follows the mounting surface of the wafer holder 52, the wafer is fixed on the wafer holder 52 and the flatness of the wafer is corrected. As described above, the positioning using the orientation flat is completed, the wafer stage 51 is moved below the alignment device (not shown), and the final wafer positioning is performed. The error in the rotation direction of the wafer detected by the alignment device is corrected by rotating the wafer holder 52 by the rotating means including the lever 54, the cam follower 55, the wedge member 56, the nut 57, the feed screw 58, and the motor 59. Wafer holder 52
The air cylinder 62 operates so that the first reference member 60 is retracted to a position where the first contact portion 60a is separated from the circumferential portion of the wafer, and the air cylinder 65 operates and the second reference member 60 rotates. The member 63 retracts to a position where the second contact portions 63a and 63b move away from the orientation flat, and the air cylinder 67 operates to move the pressing member 66 away from the circumferential portion of the wafer, so that the rotation is not hindered. It will be done after. The conventional wafer positioning apparatus shown in FIG. 3 has a configuration capable of positioning only when the orientation flat is oriented parallel to the x direction. However, a plurality of first and second contact members are provided. By providing the wafer, it is possible to position the wafer in two directions, that is, a state in which the orientation flat faces parallel to the x direction and a state in which the orientation flat faces parallel to the y direction. (For example, JP-A-60-2
No. 39024).

[0006]

However, in the above-mentioned conventional structure, since the reference member and the pressing means are provided independently of the rotation of the wafer holder, the wafer is rotated with respect to the wafer stage regardless of the rotation of the wafer holder. Will be positioned at a fixed position. Therefore, when exchanging a wafer, the rotation of the wafer holder must be returned to the reference position at the time of delivery of the wafer in order to secure a rotation stroke of the wafer holder for correcting an error in the rotation direction of the wafer. Within the same lot, the error in the rotation direction of each wafer tends to be biased in the same direction. Therefore, returning the rotation of the wafer holder to the reference position every time the wafer is exchanged causes a problem that throughput is reduced. It was Further, since the reference member and the pressing means do not move even when the wafer holder rotates, the width of the concave portion provided in the wafer holder must include the rotation stroke of the wafer holder, and the larger concave portion means that the wafer holder on the back surface of the wafer holder Since this means that the portion protruding from the mounting surface becomes large, it is not convenient in terms of flattening the wafer, and as a result, there is a problem that the transfer pattern becomes blurred due to defocus and the yield decreases.

In order to solve this problem, the present invention provides
(EN) Provided is a wafer positioning device capable of reducing a decrease in throughput caused by returning the rotation of a wafer holder to a reference position every time a wafer is exchanged and a decrease in yield due to insufficient flattening of a wafer due to an enlarged concave portion of the wafer holder. It is also.

Another object of the present invention is to provide a wafer positioning apparatus which can reduce the decrease in throughput and the yield and can position the wafer in two directions.

[0009]

The first invention of the present invention is as follows:
The first reference member, the second reference member, and the pressing means are provided so as to rotate integrally with the wafer holder by the rotating means.

According to a second aspect of the present invention, the first reference member, the second reference member, and the pressing means are provided so as to rotate integrally with the wafer holder by the rotating means, and the first reference member is provided. Two sets of the reference member and the second reference member are provided, and one of the two sets is selectively used when positioning the wafer.

[0011]

According to the first aspect of the present invention, since the first reference member, the second reference member and the pressing means are provided so as to rotate integrally with the wafer holder by the rotating means, the wafer is held in the wafer holder. Therefore, it is possible to secure the rotation stroke of the wafer holder for correcting the error in the rotation direction of the wafer without returning the rotation of the wafer holder to the reference position when replacing the wafer, The width of the recess provided in the wafer holder does not have to include the rotation stroke of the wafer holder, the recess can be made small, and it is convenient in terms of flattening the wafer.

According to the second aspect of the present invention, the first aspect
The reference member, the second reference member, and the pressing means are provided so as to rotate integrally with the wafer holder by the rotating means, and the first reference member and the second reference member are combined into two sets.
Since one of the two sets is selectively used when positioning the wafer, an error in the direction of rotation of the wafer does not have to be returned to the reference position when the wafer holder is replaced when the wafer is replaced. The rotation stroke of the wafer holder for correction can be secured, the recess provided in the wafer holder can be made small, and the wafer can be positioned in two directions.

[0013]

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

(Embodiment 1) FIG. 1 is a plan view of a wafer positioning apparatus according to a first embodiment of the present invention. In FIG. 1, the chain double-dashed line shows the outer shape of the positioned wafer. A wafer stage 1 is movable in the x and y directions in the figure. A wafer holder 2 is rotatably installed with respect to the wafer stage 1 about a point O, and can hold the wafer by vacuum suction, and also can blow gas such as air or nitrogen to release the wafer suction. Is. Further, the wafer holder 2 is provided with a concave portion 2c so that one portion of the circumferential portion of the wafer protrudes. Reference numeral 3 is a center-up, which allows vertical movement and vacuum suction / release of the wafer. Reference numeral 4 is a lever attached to the wafer holder 2, and 5 is a cam follower. 6 wedge members, 7
Is a nut, 8 is a feed screw, and 9 is a motor. The wedge member 6 and the nut 7 are integrally attached. The wafer holder 2 is rotated by rotating the motor 9 while the cam follower 5 is pressed against the wedge member 6 by elastic means (not shown). The stroke of the wafer holder 2 in the rotation direction is at most 1 to 2 degrees. Reference numeral 10 denotes a first reference member, which is fixed to the wafer holder 2 and has a first contact portion 10a that comes into contact with the circumferential portion of the wafer. Reference numeral 11 denotes a second reference member, which has second contact portions 11a and 11b that contact the orientation flat of the wafer. Reference numeral 12 is a pressing member, 13 is an air cylinder, and 14 is a bracket. The pressing member 12 and the air cylinder 13 are provided on a bracket 14 fixed to the wafer holder 2, and the pressing member 12 is brought into contact with the circumferential portion of the wafer by the action of the air cylinder 13 to move the wafer in the direction of the center O. Can be pressed.

The operation of the wafer positioning apparatus configured as described above will be described below. First,
A wafer positioned with a predetermined accuracy by a positioning device (not shown) provided outside the wafer stage 1 is carried onto the wafer holder 2 by a carrying means (not shown). At this point, the center-up 3 rises to adsorb the back surface of the wafer. Center up 3 when the transport means is retracted
Is lowered, and the wafer is placed on the wafer holder 2 with the first contact portion 10a, the second contact portions 11a and 11b, and the pressing member 1.
It is placed between the two. At this time, the pressing member 12 is retracted to a position where it does not contact the circumferential portion of the wafer. Thereafter, the wafer holder 2 blows out gas to reduce the friction between the back surface of the wafer and the mounting surface of the wafer holder 2, and in this state, the air cylinder 13 operates and the pressing member 12 presses the wafer in the direction of the point O. The wafer pressed by the pressing member 12 is
As shown by the two-dot chain line in FIG. 1, a first contact portion 10a,
It is positioned at a position determined by the three points of the second contact portions 11a and 11b. After this positioning, the wafer holder 2 holds the wafer by vacuum suction. Since the back surface of the vacuum-adsorbed wafer follows the mounting surface of the wafer holder 2, the wafer is fixed on the wafer holder 2 and the flatness of the wafer is corrected. With the above, the positioning using the orientation flat is completed, the wafer stage 1 is moved to below the alignment device (not shown), and the final wafer positioning is performed. The error in the rotation direction of the wafer detected by the alignment device is corrected by rotating the wafer holder 2 by the rotating means including the lever 4, the cam follower 5, the wedge member 6, the nut 7, the feed screw 8 and the motor 9. When the wafer holder 2 rotates,
A pressing means including a pressing member 12 and an air cylinder 13,
The first reference member 10 and the second reference member 11 rotate integrally with the wafer holder 2. Therefore, it is not necessary to retract the first reference member 10 and the second reference member 11, and it is not necessary to retract the pressing member 12 at that time. After the final positioning of the wafer, the wafer stage 1 moves below a projection lens (not shown) to start the exposure operation. When the exposure operation is completed, the wafer stage 1 returns to the delivery position with the original transfer device, and the exposed wafer and the next wafer are exchanged. When the wafer is exchanged, the pressing member 12 is retracted, but it is not necessary to return the rotation of the wafer holder 2 to the reference position, and the wafer remains rotated by the correction amount of the error in the rotation direction of the previous wafer. However, even when the rotation of the wafer holder 2 is not at the reference position due to the retraction of the pressing member 12, the first contact portion 10a and the second contact portion 1 are in contact with each other.
It is assumed that a region is secured between the pressing members 12 and 1a and 11b, in which the next wafer that has been conveyed is fitted.

As described above, according to this embodiment, it is not necessary to return the rotation of the wafer holder 2 to the reference position each time the wafer is exchanged, so that the throughput is increased. Further, since the concave portion 2c provided in the wafer holder 2 does not need to consider the rotation stroke of the wafer holder 2, the width can be narrowed, that is, the portion of the back surface of the wafer protruding from the mounting surface of the wafer holder 2 can be reduced. Therefore, it is convenient in terms of flattening the wafer, and the transfer pattern is less likely to be blurred due to defocus, so that the yield is increased.

(Embodiment 2) FIG. 2 is a plan view of a wafer positioning apparatus according to a second embodiment of the present invention. 2, the same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 2, the wafer holder 2 has three recesses 2
a, 2b, 2c are provided. Reference numerals 15 and 21 are first reference members, which are the first contact portions 1 that contact the circumferential portion of the wafer.
It has 5a and 20a, respectively. Reference numerals 16 and 22 are linear guides, and 17 and 23 are air cylinders. In the first reference members 15 and 21, the positions where the first contact portions 15a and 20a contact the circumferential portion of the wafer and the first contact portions 15a and 20a by the action of the air cylinders 17 and 23, respectively. Can be moved to and away from the wafer. In FIG. 2, both are in the former position. 18, 24
Is a second reference member, and second contact portions 18a and 18b, 24 that contact the orientation flat of the wafer.
a and 24b respectively. 19 and 25 are linear guides, and 20 and 26 are air cylinders. The second reference members 18 and 24 are actuated by the air cylinders 17 and 23, respectively, so that the second abutting portions 18a and 18b and 24a are acted upon.
And 24b are movable between a position where they contact the orientation flat and a position where the second contact portions 18a and 18b are separated from the wafer. In FIG. 2, both are in the former position. A bracket 27 is fixed to the wafer holder 2, and the first reference member 15, the linear guide 16, the air cylinder 17, the second reference member 24, the linear guide 25, and the air cylinder 26 are mounted thereon. A bracket 28 is fixed to the wafer holder 2, and a first reference member 21, a linear guide 22, an air cylinder 23, a second reference member 18, a direct guide 19, and an air cylinder 20 are mounted thereon.

In FIG. 2, the difference from FIG. 1 is that the first reference member 15 and the second reference member are a set.
And a second reference member 18, a first reference member 21 and a second reference member 24. In the wafer positioning operation according to the present embodiment, one of the two sets is selectively used, and the first and second reference members belonging to the remaining one set are retracted. When the first reference member 15 and the second reference member 18 are used, the first reference member 21 and the second reference member 24 are used in a state where the orientation flat is oriented parallel to the x direction. Are positioned such that the orientation flats are oriented parallel to the y direction. Therefore, according to this embodiment, in addition to the effect obtained in the first embodiment, the wafer can be positioned in two directions.

In the first and second embodiments,
As a rotating means for rotating the wafer holder, a mechanism including a lever, a cam follower, a wedge member, a nut, a feed screw, and a motor was used, but other rotation driving mechanism may be used, and the wafer holder is assumed to vacuum-adsorb the wafer. However, for example, it may be electrostatically adsorbed. Further, in the first and second embodiments, the air cylinder is used as the means for driving the pressing member, but other driving mechanism may be used. In the second embodiment, the air cylinder is also used as the means for driving the first and second reference members, but the use of other driving mechanism does not change the intention of the present invention.

[0020]

According to the first aspect of the present invention, the first reference member, the second reference member and the pressing means are provided so as to rotate integrally with the wafer holder by the rotating means. It is not necessary to return the rotation of the wafer holder to the reference position each time it is replaced, and the throughput is improved. Further, since the width of the concave portion of the wafer holder can be narrowed, it is convenient for flattening the wafer, defocusing is less likely to occur, and the yield is improved.

According to a second aspect of the present invention, the first reference member is provided so that the pressing means presses the second reference member so that the wafer holder is integrally rotated by the rotating means. Since two sets of the reference member and the second reference member are provided, and one of the two sets is selectively used when positioning the wafer, the effect obtained by the first invention In addition, the wafer can be positioned in two directions, which is convenient for aligning the crystal growth direction of the wafer with the pattern area on the original plate and for measuring the orthogonality of the two feed directions of the wafer stage from the transfer pattern. It has the unique effect of being good.

[Brief description of drawings]

FIG. 1 is a plan view of a wafer positioning device according to a first embodiment of the present invention.

FIG. 2 is a plan view of a wafer positioning device according to a second embodiment of the present invention.

FIG. 3 is a plan view of a conventional wafer positioning device.

[Explanation of symbols]

 1 Wafer Stage 2 Wafer Holder 4 Lever (Part of Rotating Means) 5 Cam Follower (Part of Rotating Means) 6 Wedge Member (Part of Rotating Means) 7 Nut (Part of Rotating Means) 8 Feed Screw (Part of Rotating Means) 9) motor (a part of rotating means) 10 first reference member 10a first contact portion 11 second reference member 11a second contact portion 11b second contact portion 12 pressing member (pressing means) 13) Air cylinder (a part of pressing means) 15 First reference member 15a First contact portion 18 Second reference member 18a Second contact portion 18b Second contact portion 21 First Reference member 21a first contact portion 24 second reference member 24a second contact portion 24b second contact portion

Claims (2)

[Claims] 1. A wafer positioning device for positioning a wafer on which a linear notch is provided at a part of a peripheral edge thereof at a predetermined position on a wafer stage which can be moved in a horizontal plane. A wafer holder capable of being mounted and sucked and held, rotating means for rotating the wafer holder with respect to the wafer stage, and a first reference member having a first abutting portion abutting on a circumferential portion of the wafer. A second reference member having a second contact portion that contacts the cutout of the wafer, and pressing means for pressing the wafer against the first reference member and the second reference member, on the wafer stage. The wafer is characterized in that the first reference member, the second reference member, and the pressing means are provided so as to rotate integrally with the wafer holder by the rotating means. Positioning device. 2. Two sets of the first reference member and the second reference member are provided, and the first reference member and the second reference member included in the two sets are both the first set. The contact portion and the second contact portion can be retracted to a position where they do not contact the wafer, and one of the two pairs is selectively used when positioning the wafer. The wafer positioning device according to claim 1.