JPS60239024A - Substrate positioning device - Google Patents

Abstract

PURPOSE:To enable to position correctly a substrate of wafer, etc. with a simple construction by a method wherein referential members for positioning are provided transferrably to a base. CONSTITUTION:After a wafer W is put on a holder 2, referential members 30, 40 are sent out according to air cylinders 50. Then an air cylinder 45 is operated to press the circumferential edge of the wafer W to the directions of the members 30, 40 according to a press member 46. Then coming in contact of the member 46 with the edge surface of the wafer W is released, and the operations of the cylinders 50 are suspended, the members 30, 40 are turned out from the holder 2, and coming in contact of rollers 31a, 31c, 41b (or rollers 31b, 41a, 41c) with the wafer W is released. The wafer W repositioned in such a way is conveyed up to the directly under side of a projection lens, for example, according to a stage 1, the two dimensional position in relation to a projection image is prescribed, and correction of the slippage of a rotation is also performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a positioning device for a substrate (1) such as a semiconductor wafer or a glass mask, and particularly to a positioning device suitable for an exposure apparatus that requires high positioning accuracy.

(Background of the Invention) In recent years, reduction projection type exposure apparatuses have come to be used in large numbers at production sites as exposure apparatuses for manufacturing semiconductor devices such as IC+LSIs. This apparatus uses a projection lens to reduce the image of a circuit pattern drawn on an original plate called a reticle and exposes the image onto a semiconductor wafer (hereinafter simply referred to as wafer). The size of the projected image of the circuit pattern is at most 20 cm.
Since the diameter of the wafer is approximately 100 m to 150 mm, this equipment places the wafer on a stage that moves two-dimensionally, steps the wafer against the projected image, and then exposes the wafer. The circuit pattern is transferred to the entire surface of the wafer by a step-and-repeat method in which the steps are repeated.

Normally, in order to manufacture one semiconductor device, a projection image of a circuit pattern different from the previously transferred 'i''L circuit pattern is superimposed and exposed on one wafer. (9) It is necessary to perform two-dimensional alignment and rotational misalignment correction for the projected image of C. This type of exposure equipment uses a photoelectric method to align alignment marks provided on the wafer. Detected with a microscope and aligned with the projected image (including rotation)
A so-called precision alignment device is installed to perform this. Although this alignment device has high accuracy, the area in which it detects alignment marks is extremely narrow. This does not mean that the area is simply narrow; it is narrow in the sense that the mark can be detected by searching a wide area that includes the mark, which requires a corresponding amount of search time. In other words, after positioning the stage according to the designed arrangement direction and pitch of multiple circuit patterns (hereinafter referred to as chips) formed on the wafer, the stage is positioned within the field of view of the microscope of the alignment device (detection area). If the mark is located within), the positional deviation of the mark can be detected immediately, and precise alignment including rotation can be completed in the shortest possible time. Thus, in order to satisfactorily achieve precise alignment of the wafer, the wafer is roughly positioned using linear notches (hereinafter referred to as flats) before being placed on the stage (3). This coarse positioning is called a pre-alignment device, for example,
It is disclosed in Japanese Patent No.-18713. This pre-alignment device not only performs two-dimensional rough alignment of the wafer, but also the flat position f of the transported wafer.
11. Mainly involves the operation of constantly aligning the stage in a two-dimensional moving direction (so-called orientation flat). When the orientation flatness is achieved, the wafer is transported from the pre-alignment device on a stage so that the flat position (two-dimensional direction) does not change. However, for this transportation, the wafer undergoes at least two transfer operations. One is the delivery from the pre-alignment device to the transport means, and the other is the delivery from the transport means to the stage. Such a transfer operation causes a considerable amount of misalignment of the wafer, and when the wafer is placed on the stage, the positioning accuracy achieved by the briar alignment device (4) is not preserved and becomes worse. There were drawbacks. In addition, in order to correct rotational deviation of the wafer during precise alignment, the wafer is placed on the stage via a vacuum suction holder (chuck), and this holder is installed so that it can rotate with respect to the stage. It is being

Therefore, when the exposure process for the preceding wafer is completed and the next uni... is to be received, the holder is rotated by a certain angle with respect to the moving coordinate system of the stage in order to correct the rotational deviation of the preceding wafer. is in a state of Generally, the rotation of the wafer is detected by carefully observing the marks on the wafer using a microscope of an alignment device, so the holder cannot be precisely rotated unless the wafer is placed on the wafer. For the reasons mentioned above, there is a drawback that the operation from receiving the wafer from the pre-alignment device to precise alignment becomes complicated.

(Objective of the Invention) An object of the present invention is to solve these drawbacks and provide a device (5) that accurately positions a substrate such as Ueno 1 with a simple structure.

(Summary of the Invention) The present invention comprises a holder for placing a substrate (wafer), a base (stage) for rotatably holding the holder, and a stage for positioning the substrate at a predetermined position on the holder by coming into contact with the end surface of the substrate. a reference member (roller, etc.), and a means (motor 25) for rotating the holder in order to correct rotation errors of the substrate after positioning, and the holder is mounted on a mounting section (
The shape is such that at least a part of the periphery of the substrate protrudes from the suction direction), and the reference member is at a first position where it abuts the protruding end surface of the substrate during positioning, and when the holder is rotated.
The technical point is that the base is provided so as to be movable between a second position where it does not come into contact with the end surface of the substrate.

(Embodiment) FIG. 1 is a diagram showing a schematic configuration of a wafer transport system of a reduction projection type exposure apparatus suitable for an embodiment of the present invention. FIG. 1 shows a state in which a wafer W is placed on a holder 2 on a stage 1 at a transfer position. Supply (G) A supply wafer cassette 3 stores a plurality of wafers (coated with resist) W' to be exposed. The wafer w/ (f) is transported to the turntable 5 of the pre-alignment device by the transport bells l-4, 4'.
Since it is disclosed in Publication No. 3, it will be briefly explained here.

The wafer W' is centered so that its center coincides with the rotation center of the turntable 5, and then vacuum suctioned onto the turntable 5. Although not shown, the wafer W'' attracted onto the turntable 5 is rotated by a motor, and a flat surface around the wafer W'' is photoelectrically detected.
The flat is stopped at a position facing the two rollers 6a16b.

After that, the suction of the turntable 5 is released, and the pressing member 7
When the end face of the wafer W'' is pressed, the flat of the wafer W'' comes into contact with the rollers 6a and 6b, and the other roller 6C
contacts the circumferential edge of the wafer W'' to position the wafer W''. Now, the pre-aligned sea urchin...W”M
The slider arms 9a and 9b move simultaneously along guides 8a and 8b extending parallel to the y-force direction (7), and are conveyed directly above the holder 2 of the stage 1. The wafer W transferred onto the holder 2 is pre-aligned again by the positioning device according to the embodiment of the present invention in order to ensure precision of the pre-alignment that has deteriorated due to the transfer operation. For the exposure operation, the stage 1 performs two-dimensional V-stepping on the projected image 11 of the reticle by the projection lens 0, and repeatedly exposes the wafer W. The exposed wafer W is again transferred to the turntable 5 by the slider arms 9a and 9b at the position shown in FIG.
, 12b4C into the wafer cassette 13.

Next, a positioning device according to an embodiment of the present invention will be explained based on FIGS. 2 and 3. Figure 2 is stage 1 of Figure 1.
FIG. 3 is a plan view of the positioning device provided above, and FIG. 3 is a partial sectional view thereof. The surface (placing surface) of the circular holder 2 on which the wafer W is placed is provided with, for example, a spiral suction groove 20.
is provided from the center part (8) toward the outer periphery. This suction groove is not limited to a spiral shape, but may be a concentric shape. In this groove 20, three intake holes 20a, 20 are located near the outer periphery of the mounting surface 2a.
b, 20c are provided at approximately equal angular intervals, and the intake holes 2
By evacuating from 0a, 20b, and 20c,
The wafer W is straightened into a uniform plane that conforms to the mounting surface. Three jet holes 21 a, 21 b, and 21 c are provided at approximately equal angular intervals in the groove 20 at a position close to the center of the mounting surface 2 a, and gas (air) is emitted from these jet holes 21 a, 21 b, and 21 c. , nitrogen, etc.) improves the peeling of the wafer W immediately after the vacuum suction is released, and reduces unnecessary friction generated between the wafer W and the mounting surface 2a during positioning. Now, in the area around the holder 2 where the flat F of the wafer W and a part of the circumferential edge about 90 degrees away from it are located, the flange F and the circumferential edge are separated from the mounting surface 2a. A U-shaped notch 20b that protrudes,
2e is formed. This holder 2 is provided on the stage 1 so as to be rotatable around a rotation axis 2d.

The rotation axis 2d does not coincide with the center of the mounting surface 2a of the holder 2, but is provided at an eccentric position. Furthermore, on the opposite side of the rotation axis 2d with respect to the center of the mounting surface 2a of the holder 2, there is an arm section 22 fixed to the holder 2, and at the tip of this arm section 22, an orthogonal coordinate system xy (of the stage 1 (movement coordinates) a nut 23 that is rotatably provided in the xy plane,
The feed screw 24 screwed into this nut 23 and the stage 1
A motor 25 is fixed to and rotates the feed screw 24.
is provided to rotate the holder 2.

Now, at the ends of the notches 2b and 2c around the holder 2, reference members 30 and 40 are provided which are movable relative to the holder 2 in substantially radial directions from the center of the mounting surface 2a. In FIG. 2, the reference member 30 is provided on the stage 1 via a linear ball race 30a (see FIG. 3), etc., so as to move back and forth with precision in the y direction. This reference member 30 includes three cylindrical rollers 31 a s 31 b s 31 c that abut the flange (F) or the circumferential edge of the wafer W.
are rotatably supported by the fixed plate 32 so that they are lined up at predetermined intervals in the X direction. The fixed plate 32 is fixed to a slide part 33, and the slide part 33 includes rollers 34a, 34b, and 34c that maintain straightness in the y direction in addition to the ball race 30a.
, 34d to stage 1. Further, a stopper 35 is fixed to the stage 1 at the tip of the slide portion 33 (on the side facing the holder 2). This stopper 35 regulates the extended position of the reference member 30 during repositioning. At this extended position, 3
Of the two rollers 31a131b and 31c, the rollers 31a and 31c on both sides are arranged so that the line segment connecting the valley contact position with the wafer W is parallel (coinciding) with the X-axis. (flano) contact F together. At this time,
The central roller 31b does not come into contact with the flat F, but is provided at a position separated from the flat F by a predetermined distance.

This uses the reference members 30 and 40 for both the orientation (0° repositioning) of aligning the flat F parallel to the X axis and the orientation (90° repositioning) of aligning the flan F parallel to the y axis. This is for the purpose of doing so. Now, regarding the reference member 40 as well, three rollers 41 a, 41 b, and 41 c having the same shape are connected to the roller 31 a.
, 31b, and 31c, they are rotatably supported on a fixed plate 42 so as to be lined up in the Y direction, and move forward and backward in the X direction together with the slide portion 43.

Here, three rollers 31a, 31b of each reference member.

The arrangement relationship among 31c, 41a, 41b, and 41c will be described. When repositioning at 0°, the rollers 31a and 31c abut the flat F of the wafer W, the circumferential end about 90° away from the flat F abuts the roller 41b, and the other roller 31b141a.

41c does not come into contact with the end surface of the wafer W. On the other hand, 90
In the repositioning step @, the rollers 41a and 41c are in contact with the flat F, the circumferential end is in contact with the roller 31b, and the other rollers 411), 31a, and 31c do not contact the end surface of the wafer W. By arranging each roller in this way, the direction of the orientation flat can be adjusted between θ° and 90°.
It can be used for both. By the way, the reference member 30.4
0 are moved independently by the air cylinder 50 or in conjunction with each other via a link mechanism, as shown in FIG. Also, z/'W is the roller 31. a, 31c.

A pair of 41b, also 1do-ra 41 a, 41 c, 31
An air cylinder 45 and a suppressing member 46 are fixed to the stage IK so as to press the wafer W so as to come into contact with either of the pair b. For this reason, a notch 2e is further formed in a part of the periphery of the holder 2 so that the pressing member 46 can be inserted therein.

Now, in such a configuration, in order to reposition the wafer on the stage 1, after placing the wafer W on the holder 2 as shown in FIG. After letting out the nozzle 21a,
21b and 21c blow out a gas such as air or nitrogen to form a hydrostatic air bearing between the back surface of the wafer and the mounting surface 2a. As a result, the friction of the wafer W becomes extremely small. Next, the air cylinder 45 is operated and the pressing member 46 presses the circumferential end of the way "W" onto the reference member 30.4.
Press in the 0 direction. While this suppressing operation continues, the nozzle 2
The outflow of gas (13) from 1a, 21b, 2'1c is stopped, and instead vacuum is drawn from the intake holes 20a, 20b, 20c. When this evacuation is completed, the pressing member 46 is released from contact with the end surface of the wafer W, the operation of the air cylinder 50 is stopped, and the reference member 30.
40 from the holder 2, and remove the rollers 31a and 34c.
, 41b (or rollers 31b, 41a, 41c) are released from contact with the wafer w. The amount of retraction of the reference members 30 and 40 is determined according to the maximum amount of rotation of the wafer W (holder 2) so that these rollers do not come into contact with the wafer W. This width varies depending on the size (diameter) of the wafer W, but is approximately 1 to 2 wm at most.

The wafer W thus repositioned is carried by the stage 1 to, for example, directly below the projection lens 10, and the marks on the wafer W are observed by an alignment device (microscope), and the two-dimensional position with respect to the projected image 11 is defined. At the same time, rotational deviation is also corrected. This rotational deviation is corrected by the motor 25 shown in FIG.

Next, a second embodiment of the present invention will be described based on FIG. 4 (]4). FIG. 4 is a plan view showing the situation when the 0° repositioning of the wafer W on the holder 2 is completed by the reference member 30, 40 and the pressing member 46, and the member having the same function as that shown in FIG. are given the same reference numerals. In this second embodiment, via an arm 61 having a fulcrum 60 rotatably supported on the stage 1 with 30 reference members,
It moves linearly in the y direction by the air cylinder 50a. The arm 61 reduces the length from the fulcrum 60 to the point of action of the slider 33 to about half the length from the force point of the air cylinder 50a to the fulcrum 60, so that the force of the piston of the air cylinder 50a is reduced. The biasing force of the reference member 30 in the y direction is increased to 1 or more. Similarly, the reference member 40 also moves linearly in the X direction via an arm 63 that rotates about a fulcrum 62 by an air cylinder 50b.

FIG. 4 shows the state of repositioning at 0°, so that the two rollers 31a and 31c of the reference member 30 are in contact with the flat F of the wafer W, and one roller 41b of the reference member 40 is in contact with the circumferential edge of the wafer W. is in contact with. Now, the air cylinders 50a and 50b are connected via a common pipe 70 to a solenoid valve 72 that turns on and off the supply of air. The solenoid valve 72 is further connected with a pipe 71 from the air cylinder 45 of the pressing member 46, and the three air cylinders 45.
50a, 50b are connected to a common air supply source.

With the above configuration, when the wafer W is prealigned to 00 and placed on the holder 2, the solenoid valve 72 opens and air at the same pressure is supplied to the three air cylinders 45, 50a and 50b. . Before this air supply, the piston of each air cylinder is biased by a coil spring.
The pressing member 46, rollers 31a, 31c141b, etc. have been retracted from the position where the wafer W should be repositioned. In FIG. 4, the retracted position of the suppressing member 46 and the reference member 30 (
The retracted position of the rollers 31a, 31b, 3]c) and the retracted position of the reference member 4'O (0-ra4], a, 41b, 41c) are both indicated as d. By supplying air from the solenoid valve 72, the reference members 3o, 4o are moved from the retracted position d to the position (extended position) determined by the stopper 35 as shown in FIG. During this movement, the pressing member 46 also moves toward the center of the wafer W. In this way, the reference members 30 and 40 are locked at the feeding position, and when the pressing member 46 presses the circumferential edge of the wafer W, the reference members 30 and 40
0.40 is multiplied by arms 61 and 63 respectively.
Since it is pressed against the stopper 35, the sea urchin/'
After W comes into contact with the three rollers 31a and 3Jc141b, it does not move toward the retracted position d due to the pressing force of the suppressing member 46.

As described above, the repositioning at θ° is completed, vacuum suction of the holder 2 is subsequently started, and when the suction is completed, the solenoid valve 72 is closed. As a result, the suppressing member 46 and the reference member 30, 40 return to the retracted position d by the action of the coil spring that biases the piston in each air cylinder 45, 50a 150b.

According to a non-example, the suppression member 46 and the reference member 30.40
(17) Simplification of piping and air supply source can be expected.

As described above, in the first and second embodiments of the present invention, a wafer prealignment device that performs both oo repositioning and 900 repositioning has been described. na')&meK, three (7)
Similar effects can be obtained even if the present invention is applied to a device that includes only the CI-Ra 31a, 31c, and 41b. In this case, two rollers 3'1a, 31 that contact flatly
It is also sufficient to evacuate only c. In addition, the reference member 30,
40. The pressing member 46 may be driven by vacuum. In that case, 1d cylinder 150.50a, 50b, 45
It is configured so that it is held at the retracted position by supplying 1C vacuum, and when positioning, it is moved out to a predetermined position by a spring force by stopping the vacuum supply.

This has the advantage that less dust is generated and the force of contacting (suppressing) the end face of the wafer can be adjusted to be weaker by the spring force.

(Effect of the invention) According to the present invention, the reference part for positioning/1
Q) Since the material is movable on the base, the wafer can always be positioned at a constant position with respect to the base (coordinate system In this case, it does not take much time to correct the rotation of the wafer (substrate), and the throughput can be improved. Furthermore, since the reference member is not provided on the holder, maintenance of the reference member becomes easier. For example, when positioning a wafer with photoresist many times, the fine powder of the photoresist may be in the base 1?
! It may adhere to members and reduce positioning accuracy. If the reference member is fixed on the holder as in the past, it is difficult to remove the resist that adheres to the part of the reference member near the mounting surface of the holder, but with the present invention, this problem is completely avoided. The reference member can be cleaned easily.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a schematic configuration of a wafer transport and wafer pre-positioning device for exposure apparatus rr suitable for an embodiment of the present invention, and FIG. 2 is a positioning device according to the embodiment of the present invention. 3 is a partial sectional view of FIG. 2, and FIG. 4 is a plan view schematically showing the configuration of a positioning device according to a second embodiment. 5. [Explanation of symbols of main parts] 1... Stage (base), 2... Holder, 2a... Placement surface, 25... Motor,
30.40...Reference member, 31a, 31b, 31c, 41a, 41b
, 41 c-o-la, 45.50.50a150b
−==−x A cylinder, 46...Press member, Applicant: Takao Watanabe, Agent, Nippon Kogaku Kogyo Co., Ltd.

Claims (1)

[Claims] a holder for placing a substrate thereon; a base for rotatably holding the holder; a reference member for abutting against an end surface of the substrate to position the substrate at a predetermined position on the holder; In order to correct rotation errors of the substrate, means for rotating the holder is provided, the holder has a shape such that at least a portion of the periphery of the substrate protrudes from the mounting portion thereof, and the reference member is configured to rotate the holder. The pace is provided so as to be movable between a first position in which it contacts the protruding end surface of the substrate during positioning and a second position in which it does not come into contact with the end surface when the holder is rotated. A device for positioning the board.