JPH102719A - Position-measuring apparatus and pattern-measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position-measuring apparatus and a pattern-measuring apparatus which can reduce measurement errors due to heat. SOLUTION: A first reflection member 24 is used, having a reflecting surface 24a in parallel with a first plane, containing the optical axis of an optical system 14. Holding members 36a and 36b for holding the first reflection member is held, with respect to the optical system 14, are supported at two points on the outer circumference of the optical systems 14 and 14a, crossing the first plane. A second reflection members 28 is set on an object 10 to be measured. Then, a measuring light is projected onto the first and second reflection members 24 and 28, and the light reflected on the reflecting surfaces of the first and second reflection members 24 and 28 is used to measure the degree of a relative positional displacement between the optical axis of the optical system 14 and the object 10 to be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position measuring device for measuring a relative position displacement of a measurement object with respect to an optical axis of a predetermined optical system, and a pattern of a substrate mounted on a movable stage. The present invention relates to a pattern measuring device that measures

[0002]

2. Description of the Related Art As a method for optically measuring the position of an object to be measured, an interferometer is currently widely used. In the interferometer, for example, one light beam for measurement is split into two light beams, the split light beams are guided in different directions, and the light beams reflected by the two reflecting mirrors are combined again. And these 2
By detecting interference fringes generated by combining the light of the book, it is possible to measure the displacement of the relative position between the members provided with the two reflecting mirrors. Such an interferometer system is frequently used in semiconductor device manufacturing and inspection processes. In the exposure step of transferring the pattern formed on the mask onto the photosensitive substrate, prior to the exposure operation, the coordinates of the pattern formed on the mask are measured by a pattern measuring device. In such a pattern measuring apparatus, a mask to be measured is placed on a movable stage, and the pattern on the mask is scanned by light emitted from an optical system such as an objective lens to thereby position the pattern ( (Coordinates). At this time, the position of the mask moving in the two-dimensional plane is accurately measured by the interferometer.

In the above-described pattern measuring apparatus, a reference mirror is installed on the outer periphery of a lens barrel of an objective lens, and a moving mirror is installed on a stage on which a substrate such as a mask is mounted. Then, the laser light for measurement is set to 2 in the interferometer.
The light is divided into books, and the divided light is projected onto a reference mirror fixed to an objective lens barrel and a movable mirror on a stage. Then, the light reflected by the two reflecting mirrors is combined again in the interferometer, and the position of the substrate is measured by detecting interference fringes generated by the combination of these two lights. To be exact,
The displacement of the relative position between the optical axis of the objective lens and the substrate on the stage is measured.

FIG. 7 shows a schematic configuration of a conventional pattern measuring apparatus. This device measures the position (coordinates) of a pattern 110a formed on a substrate 110, and includes an optical device 112 that emits a laser beam for pattern measurement;
An objective lens 114 for projecting a laser beam emitted from the optical device 112 as a spot on the substrate 110,
Light receiving elements 116a and 116b for receiving scattered light generated at the edge of the ten patterns 110a are provided. The substrate 110 is mounted on a stage 118 movable in a plane perpendicular to the plane of the drawing. A movable mirror 122 that reflects laser light emitted from the interferometer main body 120 is fixed to an end on the stage 118. Further, a reference mirror 124 that reflects a laser beam 123 emitted from the interferometer main body 120 is fixed to an outer periphery of a lens barrel 114 a surrounding the objective lens 114.

[0005] In the pattern measuring apparatus having the above-described configuration, by driving the stage 118, the laser spot irradiated through the objective lens 114 is applied to the substrate 1.
Scanning is performed using ten patterns 110a. Then, the scattered light generated at the edge portion of the pattern 110a is reflected by the light receiving element 116.
a and 116b. At this time, since the position of the substrate 110 is monitored by the interferometer main body 120, the position of the pattern 110a is automatically measured from the signals of the scattered light received by the light receiving elements 116a and 116b.

As shown in FIG. 8, the reference mirror 124 is held by a U-shaped holding member 126 with the reflecting surface 124a parallel to a plane including the optical axis A of the objective lens. That is, the laser light 123 emitted from the interferometer 120 is perpendicularly incident on the reflection surface 124a of the reference mirror 124. Both ends of the holding member 126 are fixed to the outer periphery of the lens barrel 114a.

In the interferometer main body 120, one laser beam is split into two beams by a beam splitter (not shown), and the two split laser beams are applied to the moving mirror 122 and the reference mirror 124, respectively. Then, the light reflected by the movable mirror 122 and the reference mirror 124 is combined again, and the interference fringes of the combined light are observed, whereby the substrate stage 118
The position of is measured. That is, based on the relative displacement between the distance from the interferometer main body 120 to the reference mirror 124 and the distance from the interferometer main body 120 to the movable mirror 122, the pattern 110a on the optical axis A of the objective lens 114 is Measure the position. Thus, the substrate 110
Since the position of (pattern 110a) is measured based on the relative displacement of the objective lens 114 with respect to the optical axis A, in order to perform accurate measurement, the reflection surface 124a of the reference mirror 124 is required.
It is important to keep the distance between the object and the optical axis A of the objective lens 114 constant.

[0008]

However, according to the above-described conventional method, when the temperature of the lens barrel 114a changes due to some influence, the reference of the lens barrel 114a and the reference mirror 124 is caused by thermal expansion or contraction. Mirror 124
The distance between the reflecting surface 124a and the optical axis A of the objective lens 114 changes.

For example, as shown in FIG.
The radius of 14a is R, the angle of the position where the end of the holding member 126 contacts the lens barrel 114a is 2θ, and the lens barrel 114 is
Assuming that the coefficient of thermal expansion of a is K1 and the amount of temperature change is T, the reference mirror 1 caused by the thermal expansion or contraction of the lens barrel 114a
The displacement ΔX1 in the direction of the 24 laser beams 123 is as follows. ΔX1 = R · K1 · T · cos θ

On the other hand, the distance from the reflecting surface 124a of the reference mirror 124 to the mounting position of the holding member 126 to the lens barrel 114a is L, the thermal expansion coefficient of the holding member 126 is K2,
Assuming that the temperature change amount is T, the thermal displacement amount ΔX2 of the reference mirror 124 (reflection surface 124a) due to the thermal expansion or thermal contraction of the holding member 126 is as follows. △ X2 = L ・ K2 ・ T

Therefore, the total displacement ΔX between the optical axis A of the projection lens 114 and the reflecting surface 124a of the reference mirror 124
Is as follows. ΔX = (R · K1 · T · cos θ) + (L · K2 · T)

Since the shape of the holding member 126 is relatively simple and does not require high precision, the holding member 126 can be formed using a material having a low coefficient of thermal expansion, which is a difficult-to-process material. . For this reason, the amount of displacement △ X2 (= LK2T) of the reflecting surface 124a of the reference mirror 124 due to the thermal displacement of the holding member 126 can be reduced to some extent. However, it is difficult to mold the lens barrel 114a (objective lens 114) from a material having a low coefficient of thermal expansion, which is a difficult-to-process material. Therefore, the displacement amount of the reference mirror 124 due to the thermal displacement of the lens barrel 114a ΔX1 (= R ·
In order to reduce K1 · T · cos θ), it is necessary to minimize the temperature change amount T. For example, when the radius R of the lens barrel 114a is 20 mm, the thermal expansion coefficient K1 of the lens barrel 114a is 15 × 10 ⁻⁶ , and θ is 15 °,
Displacement amount of reference mirror 124 (reflection surface 124a) △ X2 (= R
(K1 · T · cos θ) needs to be controlled to an accuracy of about 0.0017 ° C. or less to make the temperature change T 0.005 μm or less. In measurement performed at room temperature, such accurate temperature control is practically impossible.

When the distance between the reflecting surface 124a of the reference mirror 124 and the optical axis A of the objective lens 114 changes, the interferometer 120
This causes an error in the position of the pattern 110a measured by the measurement.

The present invention has been made in view of the above situation, and has as its object to provide a position measuring device and a pattern measuring device in which a measurement error due to heat is reduced.

[0015]

In order to solve the above problems, the present invention provides a method of measuring a relative position displacement of a measurement object (10, 10a) with respect to an optical axis (A) of a predetermined optical system (14). In the position measuring device for measuring the reflection angle (2), the reflection surface (2) parallel to the first plane (Pa) including the optical axis (A) of the optical system (14).
A first reflecting member (24) having a first reflecting member (24), which is supported at two locations on the outer periphery of the optical system (14, 14a) intersecting the first plane (Pa); (1
4) holding members (36a, 36b) for holding;
The second reflecting member (28) fixed to the measurement object (10)
And projecting measurement light onto the first and second reflecting members (24, 28), and the first and second reflecting members (24, 2).
8) a measuring means (32) for measuring a relative positional displacement between the optical axis (A) of the optical system (14) and the measurement object (10) using the light reflected by the reflecting surface of (8). ing.

In the position measuring device as described above, a portion of the holding member (36a, 36b) in contact with the outer periphery of the optical system (14a) may be formed in a shape symmetrical with respect to the first plane (Pa). desirable.

The holding member (36a, 36b) is composed of two separate arms (36a, 36b), and one end of each of the two arms (36a, 36b) is an end of the first reflecting member (24). And the other end of each of the two arms (36a, 36b) is connected to a first plane (Pa).
May be connected to two locations on the outer circumference of the optical system (14, 14a) that intersects the optical system.

Alternatively, the holding member for holding the first reflecting member (24) may be integrated with a U-shaped member (50, 52).
And the optical system (1) whose both ends intersect the first plane (Pa)
4, 14a). At this time, the first reflection member (60a, 62
a) may be formed integrally with the holding member (60, 62).

In the position measuring device as described above, the first reflecting member (24, 26) is connected to the optical system (14, 1).
The X-side first reflecting member (24) and the Y-side first reflecting member (26) in which the reflecting surfaces (24a, 26a) are arranged at two positions shifted by 90 ° about the optical axis (A) on the outer periphery of 4a). ). At the same time, the second reflection member (2
8, 30) corresponds to the first reflecting member (24, 26), and is 90 degrees centered on the optical axis (A) on the stage (20).
Place them at two locations that are offset by °. Then, the holding member (36
a, 36b, 38a, 38b) are X-side holding members (36a, 36b) that hold the X-side first reflecting member (24).
And a Y-side holding member (38a, 38b) for holding the Y-side first reflecting member (26), and reflecting surfaces of the X-side first reflecting member (24) and the Y-side first reflecting member (26). (24
a, 26a) can be adopted such that they are arranged so that the positions in the direction of the optical axis (A) coincide. Then, in order to match the positions of the reflecting surfaces (24a, 26a) of the X-side first reflecting member (24) and the Y-side first reflecting member (26) in the direction of the optical axis (A), the X-side holding member ( 36a, 36b) and one of the Y-side holding members (38a, 38b) may be combined in a state where the other is inserted.

[0020]

In the present invention as described above, the holding member (36a, 36b, 38a, 38b) allows the plane (Pa, Pb) including the optical axis (A) of the optical system (14) and the optical system ( Since the first reflecting member (24, 26) is supported at a position where the outer periphery of the optical system (1, 14a) intersects, the optical system (1
4, 14a) also undergoes thermal expansion or thermal contraction, it is possible to minimize the deviation of the reflection surface (24a, 26a) in the measurement direction (XL, YL). That is, the optical system (14, 14)
When a) is thermally expanded, the expansion propagates substantially uniformly in the radial direction about the optical axis (A), and therefore, the optical system (14, 14).
In the outer peripheral portion of a), a plane (P) including the optical axis (A)
a, Pb). Therefore, in the present invention, the holding members (36a, 36b, 38a, 38b) are located at positions where the planes (Pa, Pb) including the optical axis (A) of the optical system (14) intersect with the optical systems (14, 14a). Are connected, the thermal displacement of the optical system (14, 14a) is
The reflection surface (24a, 26) of the first reflection member (24, 26)
It propagates only in the direction parallel to a). In other words, the first
There is almost no displacement of the reflecting surface (24a, 26a) of the reflecting member (24, 26) in the measuring direction (XL, YL), and as a result, the measuring means (32, 34) It is possible to suppress a decrease in measurement accuracy due to 34).

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the following examples. In the present embodiment, the present invention is applied to a pattern position measuring device that measures coordinates of a pattern formed on a substrate such as a reticle.

[0022]

FIG. 1 shows the overall configuration of a pattern position measuring apparatus according to this embodiment. The pattern position measuring apparatus according to the present embodiment measures the position (coordinates) of a pattern formed of chromium or the like on the substrate 10, and includes an illumination system (12, 14) for irradiating measurement light, and a substrate. Light receiving system (16a, 16b, 18a, 18b) for receiving scattered light from 10
A stage driving device 22 for driving the stage 20 on which the substrate 10 is mounted, and an interferometer system (24, 26, 28, 30, 30) for measuring the position of the stage 20 (substrate 10).
32, 34), a main control device 40 for controlling the entire pattern measuring device, and a display device 42 for displaying a measurement result by the device.

The illumination system (12, 14) includes an optical device 12 for outputting a laser beam for measurement, and an objective lens 14 for guiding the laser beam emitted from the optical device 12 onto the substrate 10 as a spot. I have. The objective lens 14 is arranged in a lens barrel 14a.

The substrate 10 to be measured may be, for example, a mask such as a reticle used in a semiconductor exposure process, or a photosensitive substrate such as a wafer having the mask pattern exposed. The stage 20 on which the substrate 10 is placed is configured to be movable in an XY two-dimensional plane by a stage driving device 22 controlled by a main controller 40. And, by the movement of the stage 20,
The laser spot emitted from the objective lens 14 is
The scanning is performed on the zero surface.

The light receiving system (16a, 16b, 18a, 18b) for receiving the scattered light from the substrate 10 is arranged so as to look obliquely from above the substrate 10, and performs relative scanning between the laser light and the substrate 10. Thereby, scattered light or diffracted light generated at the pattern edge on the substrate 10 is received. Then, the main controller 4 outputs an electric signal corresponding to the intensity of the received light.
0 is supplied.

The interferometer system (24, 26,
28, 30, 32, and 34) are two-axis interferometer systems that measure the position of the substrate 10 in the X-axis direction.
4, 28, 32) and a system (26, 30, 34) for measuring the position in the Y-axis direction. The interferometer systems (24, 28, 32) for measuring the position in the X-axis direction include mounting members (36a, 36).
It comprises a reference mirror 24 fixed on the outer periphery of the lens barrel 14a by b), a long movable mirror 28 fixed to an end on the stage 20, and an interferometer main body 32. A laser light source (not shown) is provided in the interferometer main body 32. The laser light emitted from the laser light source is separated by a spectroscope (not shown) such as a beam splitter.
And splits the split light into two beams. The reference mirror 24 and the moving mirror 28
To project on. Then, the laser beams reflected by the reference mirror 24 and the moving mirror 28 are combined again in the interferometer body 32, and based on the interference fringes of the combined light, the reference mirror 24 and the moving mirror 28 are combined.
, That is, the amount of movement of the stage 20 in the X direction is measured. More precisely,
The X coordinate of the pattern on the substrate 10 existing on the optical axis A of the objective lens 14 (see FIG. 2) is measured based on the relative displacement of the reference mirror 24 and the movable mirror 28.

On the other hand, the interferometer systems (26, 30, 34) for measuring the position in the Y-axis direction are also fixed on the outer periphery of the lens barrel 14a by mounting members (38a, 38b), similarly to the systems in the X-axis direction. The reference mirror 26 includes an elongated movable mirror 30 fixed to an end of the stage 20, and an interferometer main body 34. Interferometer body 34
Is provided with a laser light source (not shown) inside like the interferometer 32. The laser light emitted from the laser light source is split into two lights by a spectroscope (not shown) such as a beam splitter. The split light is projected on the reference mirror 26 and the movable mirror 30. Then, the reference mirror 26 and the movable mirror 3
The laser light reflected at 0 is recombined in the interferometer body 34, and based on the interference fringes of the combined light, the relative position displacement between the reference mirror 26 and the moving mirror 30, that is, the stage 20
Is measured in the Y direction. More precisely, the Y coordinate of the pattern on the substrate 10 existing on the optical axis A of the objective lens 14 is measured based on the relative displacement of the reference mirror 26 and the movable mirror 30.

The two-way interferometer system (3
2, 34), the coordinate value on the XY plane of the pattern on the laser spot projected from the objective lens 14 is obtained.

FIG. 2 shows a lens barrel 14a, a reference mirror 24, and its mounting member (3) according to the first embodiment of the present invention.
6a, 36b). Here, for convenience of explanation, the attachment members (36a, 3
6b) only, and the mounting member (38) for the reference mirror 26 is shown.
The configuration of a, 38b) will be described later. The attachment members (36a, 36b) are composed of two support arms 36a, 36b formed of a material having a low coefficient of thermal expansion. One end of the support arm 36a is fixed to an end of the reflecting surface 24a of the reference mirror 24, and the other end is connected to the lens barrel 14a.
a is fixed to the outer peripheral portion. Similarly, one end of the other support arm 36b is connected to the reflection surface 2 of the reference mirror 24.
4a, and the other end is fixed to the outer periphery of the lens barrel 14a. Two support arms 36a, 36b
A space at a fixed interval is formed at an end of the reference mirror 24 on the side of the reference mirror 24 so that the laser beam XL from the interferometer 32 is not blocked.

The lens barrel 1 of the support arms 36a and 36b
The installation position on the 4a side coincides with a plane Pa including the optical axis A of the objective lens 14. The widths of the contact portions of the support arms 36a and 36b with the lens barrel 14a are designed to be symmetric with respect to the plane Pa (L1 = L2). Further, the plane Pa and the reflection surface 24a of the reference mirror 24 are arranged so as to be parallel. With this arrangement, even when the lens barrel 14a thermally expands or contracts, the displacement transmitted to the support arms 36a and 36b is parallel to the plane Pa, that is, the reflection surface 24 of the reference mirror 24.
Therefore, the reference mirror 24 itself hardly displaces in the direction of the laser beam XL (the direction perpendicular to Pa). The support arms 36a and 36b and the lens barrel 1
It is desirable that the contact area with 4a be as small as possible.

FIG. 3 shows a mounting member (3) for the reference mirror 24.
6a, 36b) and a mounting member (38) for the reference mirror 26.
a, 38b) are shown.
It should be noted that the mounting members (36a, 36
Since b) has been described, the reference mirror 26 is used here.
The following description focuses on the mounting members (38a, 38b). Mounting member for reference mirror 26 (38a, 38b)
Has substantially the same configuration as the mounting members (36a, 36b) for the reference mirror 24, and is composed of two support arms 38a, 38b formed of a material having a low coefficient of thermal expansion.
One end of the support arm 38a is connected to the reference mirror 26.
Is fixed to the end of the reflection surface 26a of the lens barrel 1 and the other end is the lens barrel 1.
4a is fixed to the outer peripheral portion. Similarly, one end of the other support arm 38b is fixed to the end of the reflection surface 26a of the reference mirror 26, and the other end is fixed to the outer periphery of the lens barrel 14a. Also, two support arms 38
The ends of the reference mirrors 26a and 38b on the side of the reference mirror 26 are formed with a space at regular intervals so as not to block the laser beam YL from the interferometer 34.

A part of the support arm 38b includes the reference mirror 24
Hole 48 through which one support arm 36a of the holding member for use passes. The heights of the reference mirrors 24 and 26 (the positions of the objective lens 14 in the direction of the optical axis A) match. Instead of inserting the support arm 36a into the insertion hole 48 formed in the support arm 38b, the support arms 38b and 36a are formed with concave portions that mesh with each other, so that the heights of the reference mirrors 24 and 26 are reduced. They may be matched.

Lens barrel 1 of support arms 38a and 38b
The installation position on the 4a side coincides with a plane Pb including the optical axis A of the objective lens 14. The widths of the contact portions of the support arms 38a and 38b with the lens barrel 14a are symmetric with respect to the plane Pb (L3 = L4). Further, the plane Pb and the reflection surface 26a of the reference mirror 26 are arranged so as to be parallel. Thus, the reference mirror 2
6 is supported by the support arms 38a and 38b at a position that intersects the plane Pb on the outer periphery of the lens barrel 14a, so that the lens barrel 14a is similar to the X-axis mounting members (36a and 36b). Is thermally expanded or contracted, the displacement transmitted to the support arms 38a and 38b is the plane P
This is the direction b (the direction perpendicular to the plane Pa).

Next, the overall operation of the pattern position measuring apparatus of this embodiment shown in FIG. 1 will be described. Before starting the pattern measurement, the optical axis A of the objective lens 14 is first aligned with a certain reference point on the substrate 10, and the so-called calibration is performed in which the measured values by the interferometer bodies 32 and 34 at that time are set to zero. Do. Then, the laser spot output from the optical device 12 via the objective lens 14 is scanned on the surface of the substrate 10 by driving the stage 20 in the XY directions by the driving device 22. When the laser spot is scanned by the pattern on the substrate, scattered light (or diffracted light) is generated at the edge of the pattern, and the scattered light is received by the light receiving elements 16a, 16b, 18a, and 18b.

At this time, in the interferometer main bodies 32 and 34, the substrate 10 (moving mirrors 28 and 30) and the objective lens 14 (reference mirror 2)
4, 26), the relative displacement in the XY directions is measured, and the measured value is supplied to the main controller 40. In the main controller 40,
The distance between the patterns on the substrate 10 is determined based on the position information supplied from the interferometer bodies 32 and 34 and the detection signals from the light receiving elements 16a, 16b, 18a and 18b, and displayed on the display device 42.

In the present embodiment as described above, the attachment members (36a, 36b, 38a, 38b) intersect the planes Pa, Pb including the optical axis A of the objective lens 14 with the outer periphery of the lens barrel 14a. Since the reference mirrors 24 and 26 are supported at the positions, even when the lens barrel 14a thermally expands or contracts, the displacement of the reflective surfaces 24a and 26a in the measurement direction (XL, YL) can be minimized. . That is, when the lens barrel 14a thermally expands, the expansion propagates substantially uniformly in the radial direction around the optical axis A of the objective lens 14, so that the outer peripheral portion of the lens barrel 14a includes the optical axis A. It will be displaced along the planes Pa and Pb. Therefore, in this embodiment, the mounting members (36a, 36b, 38a, 38) are located at positions where the planes Pa, Pb including the optical axis A of the objective lens 14 and the lens barrel 14a intersect.
Since b) is connected, the thermal displacement of the lens barrel 14a is propagated only in a direction parallel to the reflecting surfaces 24a and 26a of the reference mirrors 24 and 26. That is, there is almost no displacement in the most important measurement directions XL and YL. As a result, the position of the substrate 10 can be accurately measured.

The displacement of the reflecting mirror 24 in the measurement direction (X direction) due to the thermal expansion (thermal contraction) of the lens barrel 14a will be described below with reference to FIGS. explain. The symbols in the formula are as follows. R: radius of the lens barrel (14a, 114a) K1: coefficient of thermal expansion of the lens barrel T: amount of temperature change θ: (angle of contact between the holding member 126 and the lens barrel 114a) / 2 ε1: according to the conventional technique R: Displacement amount of reference mirror 124 R: Change amount of radius of lens barrel 14a L: Arm length of support arm 36a (36b) β: Change amount of arm angle of support arm 36a (36b) ε2: This embodiment Displacement of the reference mirror 24 due to

In FIG. 4, the radius R of the lens barrel 14a is
Is expanded by ΔR, the displacement amount ε2 of the reference mirror 24 in the X-axis direction is as follows. ΔR = R · K1 · T (1) ΔR = L · sinβ (2) ε2 = L (1-cosβ) (3) From equation (3), ε2 Can be expected to be extremely small.

In the conventional configuration shown in FIG. 8, R = 20 m
m, K1 = 15 × 10 ^-6 , θ = 15 °, T = 0.1 ° C
In this case, the displacement ε1 of the reference mirror 124 (reflection surface 124a) is as follows. ε1 = R · K1 · T · cos θ = 20 · 15 × 10 ⁻⁶ × 0.1 × cos15 = 2.9 ×
10 ^-5 (mm)

On the other hand, in the present embodiment, when L = 40 mm under the same conditions as above, the equation (1) shown above is used.
Therefore, the variation ΔR of the radius of the lens barrel 14a is as follows. ΔR = R · K1 · T = 20 × 15 × 10 ⁻⁶ × 0.1 = 3.0 × 10 ⁻⁵ (m
m)

From equation (2), the support arm 36a
The change amount β of the arm angle in (36b) is as follows. β = sin ⁻¹ (△ R / L) = sin ⁻¹ (3.0 × 10 ⁻⁵ /40)=4.297×1
0 ^-5 (deg)

Then, when the above-mentioned β is substituted into the equation (3) to obtain the displacement ε2 of the reference mirror 24, the following is obtained. ε2 = L (1-cosβ) = 40 × (1-cos4.2
97 × 10 ⁻⁵ ) <1 × 10 ⁻⁹ (mm) This value ε2 (<1 × 10 ⁻⁹ mm) is significantly different from ε1 (= 2.9 × 10 ⁻⁵ mm) according to the conventional configuration. To a small value.

FIG. 5 shows the structure of the mounting members 50 and 52 according to the second embodiment of the present invention. This embodiment is an improvement of the embodiment shown in FIGS.
Attachment members 50 and 52 for holding the members 4 and 26 are integrally formed. Then, the reference mirror 24 is mounted inside the mounting member 50, and a hole 50a through which the laser light XL passes is provided at a position corresponding to the reflection surface 24a. Further, the reference mirror 26 is mounted inside the mounting member 52,
A hole 52a through which the laser light YL passes is provided at a position corresponding to the reflection surface 26a. Some of the attachment members 52 include:
An insertion hole 56 corresponding to the insertion hole 48 of the support arm 38b shown in FIG. 4 is formed. The function of this insertion hole 56 is as follows.
It is the same as the insertion hole 48 of the support arm 38a, and a part of the mounting member 50 is inserted therethrough, and the height positions of the reference mirrors 24 and 26 (the position of the objective lens 14 in the optical axis A direction).
Are matched. Other configurations are the same as those of the embodiment shown in FIGS. 2 and 3, and thus, duplicated description will be omitted.

FIG. 6 shows the configuration of the reference mirror mounting members 60 and 62 according to the third embodiment of the present invention. This embodiment is an improvement of the embodiment shown in FIG. 5, in which the reference mirror and the mounting members 60 and 62 are integrally formed. That is, the reflecting surfaces 60a and 62a are directly formed on the surfaces of the mounting members 60 and 62. An insertion hole 64 is formed in a part of the attachment member 62. The function of this insertion hole 64 is the same as that of the insertion holes 48 and 56 of the embodiment of FIGS. 4 and 5, and a part of the mounting member 60 is inserted therethrough, and the height of the reflecting surfaces 60a and 62a in the height direction. The positions (the positions of the objective lens 14 in the direction of the optical axis A) are matched. Other configurations are the same as those of the embodiment shown in FIGS. 2, 3, and 4, and therefore, duplicate description will be omitted.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and does not depart from the gist of the technical idea of the present invention shown in the claims. Various changes are possible within the scope.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram (perspective view) showing a configuration of a pattern position measuring apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view showing a configuration of a main part (a reference mirror mounting member) of the pattern position measuring device shown in FIG.

FIG. 3 is an enlarged plan view illustrating a configuration of a main part (a reference mirror mounting member) of the pattern position measuring device illustrated in FIG. 1;

FIG. 4 is an explanatory diagram for explaining the operation of the present embodiment.

FIG. 5 is an enlarged plan view showing a configuration of a main part (a reference mirror mounting member) of a second embodiment of the present invention.

FIG. 6 is an enlarged plan view showing a configuration of a main part (a reference mirror mounting member) according to a third embodiment of the present invention.

FIG. 7 is a schematic diagram (side view) showing a configuration of a conventional pattern position measuring device.

FIG. 8 is an enlarged plan view showing a configuration of a main part (a reference mirror mounting member) of a conventional pattern position measuring device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Substrate 12 ... Optical device 14 ... Objective lens 14a ... Lens barrel 16a, 16b, 18a, 18b ... Light receiving element 20 ... Stage 24, 26 ... Reference mirror 24a , 26a, 60a, 62a ... reflecting surfaces 28, 30 ... moving mirrors 32, 34 ... interferometer bodies 36a, 36b, 38a, 38b, 50, 52, 60,
62: (reference mirror) mounting member 40: main controller 48, 56, 64: insertion hole A: objective lens optical axis Pa, Pb: plane including optical axis A XL, XY ... Laser light for measurement

Claims (8)

[Claims] 1. A position measuring device for measuring a relative displacement of an object to be measured with respect to an optical axis of a predetermined optical system, comprising: a reflecting surface parallel to a first plane including the optical axis of the optical system. A first reflecting member; a holding member that is supported at two locations on the outer periphery of the optical system that intersects the first plane and holds the first reflecting member with respect to the optical system; A fixed second reflecting member; and an optical system that projects light for measurement onto the first and second reflecting members and uses light reflected by the reflecting surfaces of the first and second reflecting members. A position measuring device comprising: a measuring unit for measuring a relative positional displacement amount between the optical axis of the object and the measurement object. 2. The position measuring device according to claim 1, wherein a portion of said holding member which is in contact with an outer periphery of said optical system is formed in a shape symmetric with respect to said first plane. 3. The holding member comprises two separate arms, one end of each of the two arms is connected to the end of the first reflecting member, and the other end of each of the two arms. 3. The position measuring device according to claim 1, wherein the position measuring device is connected to two points on the outer periphery of the optical system that intersect with the first plane. 4. The holding member is an integral U-shaped member, and both ends are connected to two locations on the outer periphery of the optical system that intersect with the first plane. Item 1
Or the position measuring device according to 2. 5. The position measuring device according to claim 4, wherein said first reflecting member is formed integrally with said holding member. 6. The X-side first reflection member and the Y-side first reflection member, wherein the first reflection member has reflection surfaces disposed at two positions on the outer periphery of the optical system, which are shifted by 90 ° about the optical axis. The second reflecting member corresponds to the first reflecting member, and has two reflecting surfaces at 90 degrees shifted from the optical axis on the stage. The holding member, An X-side holding member that holds the X-side first reflecting member and a Y-side holding member that holds the Y-side first reflecting member, the reflection of the X-side first reflecting member and the Y-side first reflecting member. The position measuring device according to claim 3, wherein the positions of the surfaces in the optical axis direction coincide with each other. 7. The X-side holding member and the Y-side holding member,
7. The position measuring device according to claim 6, wherein one of the two holding members is arranged in combination with the other being inserted therethrough. 8. A pattern measuring apparatus for measuring a pattern formed on a substrate mounted on a movable stage by using a first light irradiated through an objective lens, wherein the optical axis of the objective lens A first reflecting member having a reflecting surface parallel to a first plane, the first reflecting member being supported at two locations on the outer periphery of the objective lens intersecting the first plane, and the first reflecting member being attached to the objective lens; Holding members for holding against;
A second reflecting member fixed on the stage;
And projecting measurement light onto the second reflecting member, and using the light reflected by the reflecting surfaces of the first and second reflecting members, the relative position between the optical axis of the objective lens and the substrate. A pattern measuring device comprising: a measuring unit for measuring a displacement amount.