JPH04351905A - XY stage equipped with laser length measuring device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an XY stage for supporting a workpiece, and more particularly to an XY stage equipped with a laser length measuring device. XY stages are used in many fields to support workpieces and the like. For example, semiconductor manufacturing equipment such as a stepper includes an XY stage to support a wafer. The wafer is placed on a movable stage section of an XY stage, and the wafer is placed at a precisely determined position by moving and positioning the movable stage section. For precise positioning, it is necessary to accurately measure the position of the movable stage section.

Recently, with the miniaturization of LSIs, extremely high positioning accuracy of 1/100,000 mm has become necessary for semiconductor manufacturing equipment such as steppers. High precision measurement equipment is required. Interferometric laser length measuring devices are capable of highly accurate measurement, and are increasingly being used as means for measuring the position of a movable stage section on which a wafer is placed.

0003

[Prior Art] Interferometric laser length measurement devices utilize interference between measurement light and reference light, and conventionally have a configuration that includes an interferometer provided on a fixed part and a reflection mirror provided on a movable stage part. It has become. There are various length measurement principles, and for example, one using heterodyne interference is shown in FIG. In FIG. 6, the XY stage includes a movable stage section 1 that is movable in the Y-axis direction on a guide section 1a that is movable in the X-axis direction. Mirror 2 is attached. An interferometer 3 is arranged at a fixed portion of the XY stage so as to face each reflecting mirror 2. A laser light source 4 supplies a laser beam including a measurement light component and a reference light component to the interferometer 3. The measurement light passes through the interferometer 3, goes to the reflective surface 2, is reflected by the reflective surface 2,
It passes through the interferometer 3 again and reaches the receiver 5. The reference light enters the interferometer 3 but does not reach the reflecting surface 2, and reaches the receiver 5 together with the reflected measurement light at the interferometer 3. Therefore, the measurement light travels an extra round trip distance between the interferometer 3 and the reflecting surface 2, and the distance can be determined from the interference wave that overlaps the measurement light and the reference light.

On the other hand, in semiconductor manufacturing equipment such as steppers, the size of wafers used is becoming larger in order to improve LSI productivity. Along with this, the movable stage portion of the stepper on which the wafer is placed has also become larger, and the movable range thereof has also been required to be increased. As the movable range of the movable stage section of the stepper increases, it becomes necessary to increase the size of the reflecting mirror attached to the movable stage section in order to measure the amount of movement of the movable stage section using a laser length measuring device.

[0005]

However, in support devices that require highly accurate positioning, such as the movable stage of a stepper, the surface accuracy of the reflective surface of the reflective mirror is λ/
20 (for He-Ne laser, λ=0.6328 μm
) or higher is required. For this reason, if the reflecting mirror is made large enough to measure a long distance, it is necessary to ensure high rigidity of the reflecting mirror in order to maintain surface accuracy, and the thickness and width of the reflecting mirror must also be increased. Therefore, the weight of the reflecting mirror increases, and if the reflecting mirror is mounted on the movable stage section, the motion control performance of the movable stage section will deteriorate. Increasing the size of the reflecting mirror inevitably lowers the natural frequency of the movable stage section, resulting in a disadvantage of lowering positioning accuracy and positioning time.

The present invention reduces the weight of the reflecting mirror by fixing the reflecting mirror to a fixed part outside the movable stage part and mounting the interferometer on the movable stage part to constitute a laser length measuring device. An object of the present invention is to provide an XY stage equipped with a laser length measuring device that can prevent the performance of a movable stage section from deteriorating due to an increase in the length of the movable stage.

[0007]

[Means for Solving the Problems] Referring to FIG. 1, which is a diagram illustrating the principle of the present invention, the XY stage 10 of the present invention has two
It has a movable stage section 12 that is movable in at least two orthogonal axial directions (X, Y) within a dimensional plane. The movable stage section 12 can be provided with, for example, a support stand (not shown) on which a wafer is placed. The XY stage 10 is provided with a laser length measuring device 14 that measures the amount of movement of the movable stage section 12 using interference of laser light. Each laser length measuring device 14 includes an interferometer 16 mounted on the movable stage section 12 and a reflection mirror 18 provided on the fixed section of the XY stage 10. When a laser light source (not shown) is provided at a fixed portion of the XY stage 10, the laser light is supplied from the laser light source to the interferometer 16 through, for example, an optical fiber. The interferometer includes a polarization separation means such as a beam splitter, and separates the laser beam into a portion (measurement beam) and a remaining portion (reference beam). A portion of the separated laser light (measurement light) passes through the interferometer 16, is reflected by the reflection mirror 18, and returns to the interferometer 16. The remaining portion of the separated laser beam (reference beam) does not head toward the reflecting mirror 18, but interferes with a portion of the laser beam that has been reflected and returned, thereby detecting the position of the movable stage section 12. This is what I did.

[0008]

[Operation] In the present invention, as shown in FIG.
The amount of movement of the movable stage section 12 is measured. Reflection mirror 1
8 is provided at a fixed position. Therefore, if the movable range of the movable stage portion 12 becomes larger, the length of the reflecting mirror 18 may be increased accordingly. Since the reflecting mirror 18 is located at a fixed portion, even if the reflecting mirror 18 becomes larger, the weight of the movable stage portion 12 does not increase accordingly. Therefore, even if the movable range of the movable stage section 12 becomes larger, the performance of the XY stage does not deteriorate, such as a decrease in control performance or positioning accuracy of the movable stage section 12, or an increase in positioning time.

[0009]

Embodiment FIG. 2 is a diagram showing a first embodiment of the present invention. The XY stage 10 includes a fixed base portion 20 and a movable stage portion 12 provided on the base portion 20. An X-axis linear guide 22 is provided on the base portion 20, and a guide portion 24 is slidably attached to the X-axis linear guide 22. This guide section 24 is provided with a Y-axis linear guide 26, and the movable stage section 12 is slidably attached to this Y-axis linear guide 26. Therefore, the movable stage section 12 is movable in at least two orthogonal axial directions (X, Y) within a two-dimensional plane. When this XY stage 10 is used in semiconductor manufacturing equipment such as a stepper,
A wafer support 30 can be provided on the movable stage section 12 in any desired shape.

The laser length measuring device 14 includes a movable stage section 1
2, and a reflecting mirror 18 fixed to a fixed block 32 attached to the base portion 20 of the XY stage 10. The interferometers 16 are arranged along two perpendicular sides of the movable stage section 12 so as to be at approximately the same height as the wafer support 30, and the reflecting mirrors 18 are arranged opposite to each interferometer 16.

A laser tube 34 is located on the base 20 of the XY stage 10, and an optical fiber 36 extends between the laser tube 34 and each interferometer 16. In the embodiment, the laser tube 34 includes a light source that generates polarized laser light and a receiver that receives the laser light that has interfered with each interferometer 16 and converts it into an electrical signal.

FIG. 3 is a detailed diagram of the interferometer 16 of FIG. 4 shows the optical path of FIG. 3, (A) shows the optical path of the measurement light within the interferometer 16, and (B) shows the optical path of the reference light. 3 and 4, each optical fiber 36 includes an input optical fiber 36a that supplies laser light from the laser tube 34 to the interferometer 16, and an input optical fiber 36a that supplies laser light from the interferometer 16 to the laser tube 34.
and an output optical fiber 36b that carries output light that sends processed light to a receiver within. Also shown in FIGS. 3 and 4 is a reflective mirror 18.

A collimating lens 38 is disposed near the end of the input optical fiber 36a so that the laser light supplied from the input optical fiber 36a becomes a parallel beam. A beam splitter 40 is located ahead of the collimating lens 38.
will be provided. Beam splitter 40 has an oblique polarization plane 4
1, and separates the laser light supplied from the laser tube 34 into measurement light and reference light. In the embodiment, the laser tube 34 provides a single wavelength laser beam, but is arranged so that the beam splitter 40 intersects the plane of polarization at 45°, so that the laser beam in FIGS. ), in the polarization plane 41, part of the laser light (measurement light) is transmitted, and the remaining part (reference light) is reflected.

A quarter-wave plate 42 is arranged between the beam splitter 40 and the reflecting mirror 18 at the far end of the beam splitter 40 in the transmission direction. Furthermore, a first corner cube 44 is arranged on the other side of the beam splitter 40 in the reflection direction, and furthermore, a second corner cube 46 is arranged on the opposite side of the beam splitter 40 from the first corner cube 44. . Furthermore, an inverted telescope 4 is placed in one corner of the beam splitter 40 opposite to the reflecting mirror 18.
8 is placed.

Therefore, as shown in FIG. 4(A),
The laser beam transmitted through the beam splitter 40 shifts in phase by 90 degrees while passing through the quarter-wave plate 42, becomes circularly polarized light, reaches the reflecting mirror 18, is reflected by the reflecting mirror 18, and becomes circularly polarized light. While passing through the wave plate 42, the phase is further changed to 90
The degree is off. Therefore, the reflected light is 9
It rotates 0 degrees and returns to the beam splitter 40. Therefore,
This reflected light no longer passes through the beam splitter 40,
The beam is reflected by the beam splitter 40, changes direction, and enters the second corner cube 46. This incident light is reflected twice by the second corner cube 46, enters the beam splitter 40, is reflected by the beam splitter 40, and
The light passes through the quarter-wave plate 42 again and heads toward the reflecting mirror 18. At this time, the optical path is parallel to the first direction toward the reflecting mirror 18, but is shifted downward from above the beam splitter 40. This laser light is then reflected by the reflection mirror 18 and returns to the beam splitter 40 through the quarter-wave plate 42. This laser beam is transmitted through a quarter-wave plate 4
By passing through the beam splitter 2 twice, the plane of polarization is further rotated by 90 degrees, and the plane of polarization is rotated by 180 degrees with respect to the plane of polarization at the time of initial supply. leading to.

As shown in FIG. 4B, the laser beam reflected by the beam splitter 40 is incident on the first corner cube 44. As shown in FIG. This incident light is reflected twice at the first corner cube 44 and then sent to the beam splitter 40.
The beam enters the beam, is reflected by the beam splitter 40, and exits from the beam splitter 40 in a direction opposite to the initial direction of incidence. The output optical path of this reference light overlaps with the output optical path of the measurement light shown in (A), and reaches the inverted telescope 48. In this way, the measurement light and the reference light are sent through the output optical fiber 36b to the receiver in the laser tube 34, where the interference waves are converted into electrical signals and processed, thereby converting the interferometer 16 and the reflecting mirror 1.
8 can be calculated.

In the embodiment shown in FIGS. 3 and 4, the output optical fiber 36b is composed of a plurality of output optical fibers 36c, and some auxiliary optical fibers are connected between the inverted telescope 48 and the plurality of output optical fibers 36c. Optical elements are arranged. These optical elements include, for example, a beam splitter 50,
54, 60, right angle prism 56, 58, 6
2, as well as a half-wave plate 52 and a quarter-wave plate 64
It is. This configuration is a means for detecting the phase shift between the measurement light and the reference light, and detecting the straight direction and the straight distance of the mirror.

FIG. 5 is a diagram showing a second embodiment of the present invention. The basic configuration is almost the same as the embodiment shown in FIG. XY
The stage 10 includes a fixed base part 20 and this base part 2.
A guide section 24 is provided on the X-axis linear guide 22, and the movable stage section 12 is slidably attached to the Y-axis linear guide 26. Further, the laser length measuring device 14 includes the movable stage section 1
2 and a reflecting mirror 18 fixed to a fixed block 32. Movable stage section 12
A wafer support (not shown) can be provided on the wafer in any desired configuration.

In this embodiment, the laser tube 3
4 to the interferometer 16, a beam bender 70 and a beam splitter 72 are connected to the optical fiber 36 in FIG.
provided in place of. In addition, the auxiliary beam bender 7
4 and 76 are provided on the base part 20, and the laser tube 3
4 laser beams are sent to the beam bender 70. The beam bender 70 is attached to the guide section 24, and the beam splitter 72 is attached to the movable stage section 12 to connect each interferometer 1.
A laser beam is supplied to 6. In this way, the optical fiber 36
Even without using a
4 to the interferometer 16 on the movable stage section 12.

[0020]

[Effects of the Invention] As explained above, according to the present invention,
The reflective mirror is set at a fixed position, the interferometer is mounted on the movable stage, and the laser beam is guided there to measure the amount of movement of the movable stage, so the movable range of the movable stage is Even if the size increases, the length of the reflecting mirror can be lengthened accordingly, and the weight of the movable stage section can be prevented from increasing, resulting in a decrease in control performance and positioning accuracy of the movable stage section, and a decrease in positioning time. There is no deterioration in the performance of the XY stage such as an increase in .

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention.

FIG. 2 is a diagram showing a first embodiment of the present invention.

FIG. 3 is a detailed view of the interferometer of FIG. 2;

FIG. 4 is a diagram showing the optical path within the interferometer of FIG.
) shows the optical path of the measurement light, and (B) shows the optical path of the reference light.

FIG. 5 is a diagram showing a second embodiment of the present invention.

FIG. 6 is a diagram showing a prior art.

[Explanation of symbols]

10...XY stage 12...Movable stage part 14...Laser length measuring device 16...Interferometer 18...Reflection mirror 34...Laser tube 36...Optical fiber 40...beam splitter 42...quarter wave plate 44,46...corner cube 70...beam bender 72...beam splitter

Claims (4)

[Claims] 1. A fixed part (20), a movable stage part (12) movable in at least two orthogonal axes directions in a two-dimensional plane, and a moving amount of the movable stage part using interference of laser light. In the XY stage, the laser length measuring device (14) is mounted on a laser light source (34) and the movable stage section (12) of the XY stage. interferometer (16) and the XY
It consists of a reflecting mirror (18) provided on the fixed part of the stage, and a part of the laser beam guided from the laser light source to the interferometer is reflected by the reflecting mirror, returns to the interferometer, and then returns to the reflecting mirror. An XY stage equipped with a laser length measuring device characterized in that the laser beam interferes with the remaining part of the laser beam that is not directed. 2. The laser light source (34) is provided on the fixed part (20) of the XY stage, and the optical fiber (36)
) from the laser light source (34) to the movable stage section (12).
2. The XY stage equipped with a laser length measuring device according to claim 1, wherein the XY stage is provided to guide laser light to the interferometer (16) of the laser length measuring device. 3. The interferometer (16) includes a beam splitter (40) that transmits a portion of the laser beam and reflects the remaining portion, and a beam splitter (40) that transmits a portion of the laser beam and reflects the remaining portion. A quarter wavelength plate (42) disposed between the reflecting mirror (18) and a first corner cube (42) disposed at the front in the direction of reflection of the laser beam.
4), and a second corner cube (4) disposed on the opposite side of the beam splitter from the first corner cube.
6) An XY stage equipped with the laser length measuring device according to claim 1 or 2, comprising: 4. A plurality of the interferometers (16) and beam splitters (72) are provided on the movable stage section (12), and a plurality of interferometers (16) and beam splitters (72) are provided on the movable stage section (12), and a plurality of interferometers (16) and beam splitters (72) are provided on the movable stage section (12), and a plurality of interferometers (16) and beam splitters (72) are provided on the movable stage section (12).
2). The XY stage equipped with a laser length measuring device according to claim 1, wherein laser light is supplied to the plurality of interferometers (16) through a laser beam length measuring device.