JPH10267615A - Position measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position measuring instrument having an adjusting optical system which adjusts a plurality of luminous fluxes so that the luminous fluxes which are required for position measurement may be emitted under prescribed conditions when the surface of an object is irradiated with the luminous fluxes under the prescribed conditions. SOLUTION: A position measuring instrument is provided with an illuminating optical system 100 which has a luminous flux splitting section which splits a luminous flux from a light source 1 into a plurality of illuminating luminous fluxes for measurement and makes the illuminating luminous fluxes in parallel with each other. A correcting optical system 200 has a section which makes the illuminating luminous fluxes in parallel with each other. A beam waist position changing section changes the beam waist positions of a luminous flux shifting section which displaces the illuminating luminous fluxes for measurement in parallel with each other and the illuminating luminous fluxes for measurement. An emitting optical system 300 emits the illuminating luminous fluxes for measurement upon the pattern 12 of an object 10. A light receiving optical system 400 receives diffracted light from the pattern 12. A light receiving section 500 and a signal processing section measures the position of the object 10 based on the phases of interference signals for measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing machine for processing the surface of an object to be processed and a measuring machine for measuring the surface condition of the object to be measured. It relates to a measuring device. Further, the present invention relates to an electron beam lithography apparatus to which the position measurement device is applied.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor exposure apparatus, a desired circuit pattern on a previously created original image pattern (reticle or mask) is aligned with an exposure area on a wafer and then transferred. This transfer device is a high-precision reduction exposure projection device, and the wafer side is fixed to a high-precision XY stage so that the entire surface of the wafer to be transferred can be exposed. A posting transfer device for performing step & repeat on the wafer optical system is called a stepper. With the recent increase in the degree of integration of LSIs, the circuit line width required for semiconductor devices has become increasingly smaller. Conventionally, the reduction ratio of a stepper is 1/5, but it has been said that a pattern of 1 μm or less cannot be resolved due to the wavelength limit so far. However, improvements in optical systems and illumination systems, and the emergence of phase shift masks and the like for adjusting the phase of light on a reticle have resulted in the resolution of sub-μm-order patterns. As the resolution is improved, the depth of focus of the reduction lens becomes shallower, and the accuracy of transferring an original image pattern created in advance onto a wafer is required to have a stricter value. Therefore, it is required that the alignment optical system of the stepper detect the position of the sample in the sample surface direction and the focus direction with high accuracy.

The phase shift mask reduces the phase of light passing through the exposure light transmitting portion on the original image pattern, that is, the optical path length of the transmitting portion by etching the thickness of the substrate,
Alternatively, it is changed by a method such as adding a material having a different refractive index. Therefore, to manufacture a phase shift mask, a method in which a substrate of a specific light transmitting portion is dug in the thickness direction and the optical path length is selectively changed, or a resist is applied again to a substrate on which a pattern has been drawn in advance. Then, a method of adding a material for partially changing the phase of the light transmitting portion and then etching the unnecessary portion is adopted. In any case, it is necessary to expose the resist at a predetermined position with high accuracy using the pattern drawing apparatus.

[0004]

Prior to detection of an alignment mark on a mask, the position of an exposure beam is measured and calibrated using a mark provided on a stage. Since the position of the stage is monitored with high accuracy by the laser interferometer, the position and displacement of the beam can be measured with reference to the coordinate system of the laser interferometer.
However, in the electron beam exposure apparatus, if dirt adheres to the inside of the lens barrel, the electron beam drifts due to charge-up, and the measured value fluctuates. Since the measurement of the mark position on the mask is an indirect measurement through the mark on the stage,
When the measurement value fluctuates, it is impossible to distinguish whether the cause is a beam drift or the mark itself is displaced.

[0005] In an electron beam writing apparatus or a stepper,
As a means for accurately measuring the mark position without being affected by the drift, a method using a device provided with a measurement optical system using laser light is considered. However, electron beam lithography systems and steppers require high-precision measurement. Therefore, in a type that irradiates a plurality of laser beams onto a predetermined diffraction pattern and obtains positional information from the diffracted beams, each laser beam It is necessary to make adjustments such as strictly aligning the positions to be irradiated. In particular, when employed in an electron beam lithography apparatus, the object is placed in a chamber that has been evacuated to a vacuum, while the light source and the like are placed outside the chamber. For this reason, even when the chamber satisfies the predetermined irradiation conditions when the chamber is at atmospheric pressure, the predetermined irradiation conditions often collapse when the chamber that actually needs to be measured is reduced to a vacuum.

When measuring not only a plane parallel to the object but also a position in a normal direction of the plane, it is necessary to irradiate at least three laser beams under predetermined conditions. Thus, it has been desired to provide a device for adjusting a plurality of measurement light beams so that the alignment pattern can be irradiated under predetermined conditions.

[0007]

Accordingly, an object of the present invention is to (1) irradiate a plurality of light beams required for position measurement on a target surface under predetermined conditions so that they are irradiated under predetermined conditions. An object of the present invention is to provide a position measuring device having an adjusting optical system for adjusting. (2) Position adjustment is performed in the plane direction so as to irradiate a predetermined position measurement pattern with a plurality of laser beams, and adjustment is performed so that the beam waist position coincides with the position measurement pattern. It is an object of the present invention to provide a position measuring device that can perform the position measurement. (3) An object of the present invention is to provide a small and high-accuracy electron beam lithography system having a position measurement device capable of accurately measuring the position of an object.

[0008]

SUMMARY OF THE INVENTION A position measuring apparatus according to the present invention has a light beam splitting unit for separating a light beam from a light source unit that emits a coherent light beam into a plurality of measurement light beams. And an illumination optical system that makes the light beams parallel to each other, and a portion that makes the plurality of measurement illumination light beams received from the illumination optical system parallel to each other. A correction optical system having a light beam shift unit for translating the beam and a beam waist position changing unit for changing the beam waist position of the plurality of measurement illumination light beams, and the positions of the plurality of measurement illumination light beams should be measured. An irradiation optical system for irradiating the positioning pattern provided on the object, and a receiving unit for receiving the diffracted light from the positioning pattern irradiated by the plurality of measurement illumination light beams by the irradiation optical system. An optical system, a light receiving unit for forming a measurement interference signal to receive the diffracted light received by the light receiving optical system,
A signal processing unit that measures the position of the object based on the phase of the measurement interference signal.

With such a configuration, when irradiating a plurality of light beams required for position measurement on the object surface under predetermined conditions, it can be adjusted so as to irradiate them under predetermined conditions. Thus, a highly accurate light source of the position measuring device can be realized. Further, the light beam shift unit of the position measuring device of the present invention includes at least a pair of prisms that are rotatably provided around the optical axis, and adjusts the moving distance of the irradiation position by changing the intersection angle of the prisms. It is preferable that the moving direction of the irradiation position of the measurement illumination light beam is adjusted by changing the direction of the bisector of the intersection angle of the prism. With such a configuration, a small and highly accurate position measuring device can be realized.

Further, the beam waist position changing unit of the position measuring device of the present invention has at least a convex lens and a concave lens, and changes a distance between the convex lens and the concave lens to thereby provide a beam waist position of a plurality of illumination light beams for measurement. Is preferably changed. With such a configuration, the beam waist positions of the plurality of measurement illumination light beams can be reliably changed. The illumination optical system of the position measuring device according to the present invention includes a first measurement illumination light beam and a second measurement illumination light beam emitted at a first incident angle;
Forming a third measurement illumination light beam irradiated at a second incident angle different from the incident angle;
The correction optical system that receives the second measurement illumination light beam and the third measurement illumination light beam arranges the first measurement illumination light beam and the second measurement illumination light beam with the optical axis interposed therebetween, and performs the third measurement illumination light. The luminous flux is arranged at a peripheral position more than these, and the light is changed in the optical path of the third illuminating luminous flux in the correction optical system so that the incident angle at which the third illuminating luminous flux irradiates the two-dimensional pattern is changed. It is preferable that a parallel flat plate having a rotation axis in a direction orthogonal to the axis is arranged.

With such a configuration, it is possible to realize a small and highly accurate illumination optical system of the position measuring device. Further, the illumination optical system of the position measuring device according to the present invention includes a first measurement illumination light beam of a first frequency from the coherent light beam of the light source unit,
A frequency shifter that forms a second measurement illumination light beam having a second frequency different from the first frequency; a first plane position measurement light beam and a first normal separated by separating the first measurement illumination light beam Forming a direction measurement illumination light beam, separating the second measurement illumination light beam to form a second plane position measurement light beam and a second normal direction measurement illumination light beam; and an irradiation optical system, The two-dimensional pattern is irradiated as a positioning pattern, and the light receiving optical system is configured to combine a high-order diffracted light and a zero-order diffracted light by the two-dimensional pattern of the first measurement illumination light beam and the second measurement illumination light beam. The light receiving unit is configured to receive a combination of the diffracted lights having different frequencies in any one of the combinations of the second-order diffracted lights, and the high-order diffraction by a two-dimensional pattern of the first measurement illumination light flux and the second measurement illumination light flux. A plane position measurement interference signal for performing position measurement in a plane provided with a two-dimensional pattern of an object from a combination of diffracted lights having different frequencies of any one of a combination of a diffracted light with a zero-order diffracted light and a combination of higher-order diffracted lights. A normal direction in which the position of the object is measured in the normal direction from the combination of the 0th-order diffracted light of the first measurement illumination light beam or the second measurement illumination light beam and the 0th-order diffraction light of the third measurement illumination light beam. The signal processing unit is configured to form an interference signal for position measurement, the signal processing unit measures the position of the object in the plane direction based on the phase of the interference signal for plane position measurement, and based on the phase of the interference signal for normal direction measurement. Preferably, it is configured to measure the position of the object in the normal direction.

With such a configuration, a small and highly accurate position measuring device can be realized. Further, the present invention provides
In the electron beam lithography apparatus, the position measurement apparatus of the present invention is provided so as to avoid the mounting positions of the components of the electron beam lithography apparatus and their maximum operating ranges, and the position measurement apparatus determines the position of the object. An illumination-side optical member for irradiating a position-measuring light beam for measurement, and a light-receiving-side optical member for receiving reflected diffraction light from the object and measuring the position of the object, and The illumination-side optical member and the light-receiving member are arranged so that the light beam emitted from the optical member and incident on the light-receiving-side optical member can pass through the mounting positions of the components of the electron beam lithography apparatus and their maximum operating ranges. The side optical member is arranged in the electron beam drawing apparatus.

With this configuration, the position of the object to be processed can be accurately measured, and the object to be processed can be processed with extremely high accuracy by the electron beam drawing apparatus.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the position measuring apparatus of the present invention includes an illumination optical system 100, a correction optical system 200, an irradiation optical system 300, and a light receiving optical system 400. [1] Illumination Optical System 100 Referring to FIG. 1 and FIGS. 16 to 18, which are partially enlarged views of FIG. 1, a light source 1 is a light source that emits coherent light to be an illumination light beam, and He-Ne having a wavelength λ = 633 nm. It is a laser light source. A coherent laser beam having a strong coherence emitted from the light source 1 is passed through a relay lens 102 to a beam splitter 103, where the first illumination beam 10
4 and a second illumination light beam 105.

The first illuminating light beam 104 is a relay lens 106
To the first frequency shifter 108, which modulates the first illumination light beam 104 to generate a first
A measurement illumination light beam 110 is formed. Second illumination light beam 105
Is the second frequency shifter 10 via the relay lens 107
The second frequency shifter 109 modulates the second illumination light beam 105 to form a second measurement illumination light beam 111. It is preferable to use an acousto-optic device (AOM) as the frequency shifter. The modulation frequency of the first measurement illumination light beam 110 by the frequency shifter is 80.05 MHz,
The modulation frequency of the second measurement illumination light beam 111 by the frequency shifter is 80.0625 MHz. The first measurement illumination light beam 110 and the second measurement illumination light beam 111 whose frequencies are slightly different from each other due to the frequency shifters 108 and 109.
Is formed. In this case, the first measurement illumination light beam 110
The difference Δf between the frequency of the second measurement illumination light beam 111 and the second measurement illumination light beam 111 is 12.
5 KHz. When the first measurement illumination light beam 110 and the second measurement illumination light beam 111 overlap each other and interfere with each other, the intensity of the interference result becomes a beat (beat signal) of the frequency Δf.

The beam splitter 112 splits the first measurement illumination light beam 110 into a first plane position measurement illumination light beam 114 and a first normal direction measurement illumination light beam 115. The beam splitter 113 includes a second measurement illumination light beam 111.
Are divided into a second plane position measurement illumination light beam 116 and a second normal direction measurement illumination light beam 117. First plane position measurement illumination light beam 114, first normal direction measurement illumination light beam 11
5, the illumination light flux 116 for measuring the second plane position, and the illumination light flux 117 for measuring the second normal direction,
8, 119, 120, 121, the adjustment optical system 200
Are guided as light beams parallel to each other with respect to the optical axis. However, the illumination light flux 115 for the first normal direction measurement and the second
The normal direction measurement illumination light beam 117 can also be branched from a measurement illumination light beam separate from the first plane position measurement illumination light beam 114 and the second plane position measurement illumination light beam 116, respectively.

Here, in the illumination optical system 100, the light source 1 and the first frequency shifter 108 and the second frequency shifter 109 have a conjugate relationship by the relay lenses 102, 106 and 107. [2] Adjusting Optical System 200 As shown in FIGS.
The illumination light beam 114 for measuring the plane position, the illumination light beam 115 for measuring the first normal direction, the illumination light beam 116 for measuring the second plane position, and the illumination light beam 117 for measuring the second normal direction are adjusted to conform to predetermined irradiation conditions. This is an optical system that performs correction. For the correction, the irradiation angles of the first normal direction measurement illumination light beam 115 and the second normal direction measurement illumination light beam 117 are changed to the first plane position measurement illumination light beam 114 and the second plane position measurement illumination light beam 11.
6, an irradiation angle adjustment for adjusting the position of the illumination light 6, a plane position adjustment for adjusting a plane position on an object irradiated by the four illumination light beams 114 to 117, and the four illumination light beams 11.
There are three types of beam waist position adjustment for adjusting the beam waist positions 4 to 117 so as to be on the object 10.

The irradiation angles of the first normal direction measuring illumination light beam 115 and the second normal direction measuring illumination light beam 117 are adjusted by the parallel plane plates 201 and 20 inserted in the respective optical paths.
2 is rotated about a rotation axis orthogonal to the optical axis. The first normal direction measuring illumination light beam 115 and the second normal direction measuring illumination light beam 117 are
Due to the rotation of 1, 202, they are translated in the vertical direction, and as a result, the irradiation angle by the projection lens described later changes. Here, the “vertical direction” refers to four illumination light fluxes 114 to 11.
7 refers to a direction perpendicular to the plane including 7. The four measurement illumination light beams 114 to 117 are narrowed by two mirrors (not shown) in their respective optical paths, and are incident on a pair of wedge prisms 203 and 204 having the same apex angle.

Adjustment of the plane positions of the four measurement illumination light beams 114 to 117 is performed by adjusting the intersection angle of the wedge prisms 203 and 204 and adjusting the intersection center direction with the horizontal direction as the central axis for adjustment. . The distance from the position before the adjustment is determined by adjusting the intersection angle of the wedge prisms 203 and 204. The direction of the change from before the adjustment is determined by adjusting the center direction where the wedge prisms 203 and 204 intersect. By performing the adjustment in this manner, the adjustment of the plane position of the four measurement illumination light beams 114 to 117 can be performed in any direction of up, down, left, and right. Four measurement illumination beams 114
After adjusting the plane position by the wedge prisms 203 and 204, the light enters the focus lenses 205 and 206.

The distance between the focus lenses 205 and 206 is changed so that the distance between each light beam and the optical axis can be changed while maintaining the condition that each light beam is parallel to the optical axis. And four measuring illumination light fluxes 1
The position of the beam waist can be adjusted in the optical axis direction so that the beam waists 14 to 117 are on the object 10. In the embodiment of the present invention, the adjustment lens 205 on the light source side is formed by a plano-convex lens, and the adjustment lens 206 on the object side is formed by a plano-concave lens 206. Therefore, when the distance between the focus lenses 205 and 206 is increased, the position of the beam waist changes so as to approach the light source side. However, it is also possible to form the focus lens 205 on the side with the light source 1 by a plano-concave lens 206 and to form the focus lens 206 on the side with the object 10 by a plano-convex lens.

As described above, the first plane position measuring illumination beam 114 and the second plane position measuring illumination beam 11 are located near the optical axis.
6 are arranged, and the first normal direction measurement illumination light beam 115 and the second normal direction measurement illumination light beam 117 for adjusting the irradiation angle based on these are arranged around (on both sides) the irradiation. Parallel plane plate 2 as an optical element for adjusting the angle
It is possible to easily arrange a mechanism that arranges the optical discs 01 and 202 in their optical paths and that can rotate about a rotation axis orthogonal to the optical axis. [2-1] Manual Adjustment A method of adjusting the beam of the adjustment optical system 200 described above will be described. Hereinafter, the adjustment method giving priority to the position will be described. In the initial state, the wedge prisms 203, 2
04 is arranged in the opposite direction as if rotated by 180 degrees, and apparently has no prism power. The adjusting lenses 205 and 206 are arranged so that the interval between them is substantially zero, and it is assumed that there is no power.

In the adjustment method giving priority to this position,
Using the wedge prisms 203 and 204, the irradiation position of the beam in the initial state is moved onto the mark 12 to be irradiated originally, and then the beams of the four illumination light beams 114 to 117 for measurement are adjusted using the adjustment lenses 205 and 206. The beam waist position is adjusted so that the waist is on the object 10. Specifically, the moving direction of the beam coincides with the direction of the bisector of the crossing angle of the wedge prisms 203 and 204, so that the direction of the mark 12 to be irradiated with the beam is determined based on the beam irradiation position in the initial state. The two wedge prisms 203 and 204 are rotated so that the direction of the bisector of the intersection angle coincides. Next, the beam movement distance increases as the crossing angle of the wedge prisms 203 and 204 approaches 180 degrees from 180 degrees, so that the direction of the bisector of the crossing angle of the wedge prisms 203 and 204 is By adjusting the crossing angle of the wedge prisms 203 and 204 while maintaining the same, it is possible to adjust so as to irradiate the two-dimensional pattern 12 on the object 10.

As described above, the four measurement illumination light beams 114
After adjusting the beam positions of .about.117 to be on the two-dimensional pattern 12 on the object 10, the beam waist position on the object 10 is changed based on the influence factors such as the maximum intensity of the interference signal. The distance between the adjustment lenses 205 and 206 is adjusted so as to be on the pattern 12. In the embodiment of the present invention, the adjustment lens 20 on the side where the light source 1 is located
5 is formed by a plano-convex lens, and the adjustment lens 206 on the side of the object 10 is formed by a plano-concave lens 206. Therefore, as the distance between the adjustment lens 205 and the adjustment lens 206 is increased, the beam waist position is shifted toward the light source. Get closer. [3] Irradiation Optical System 300 As shown in FIGS. 2 to 4, the irradiation optical system 300 includes folding mirrors 301 and 302 and an illumination lens 303, a first plane position measurement illumination light beam 114, and a second plane position measurement. Illumination light beam 116, first normal direction measurement illumination light beam 1
Four light beams 15 and the second normal direction measurement illumination light beam 117 are projected onto the two-dimensional pattern 12 on the object 10 at one point.

At this time, as a result of the predetermined correction performed by the correction optical system 200, the irradiation optical system 300 outputs the first plane position measurement illumination light beam 114 and the second plane position measurement illumination light beam 116 together with the object. Irradiation is performed at an incident angle θ1 with respect to a normal line of a plane including 10, and a first normal direction measuring illumination light beam 115 is irradiated at an incident angle θ2 different from the incident angle θ1.
The illumination light beam 117 for the second normal direction measurement is irradiated at an incident angle θ3 different from θ1 and θ2. The irradiation optical system 300 including the irradiation lens 303 is configured such that the beam waist position is adjusted in a state where the adjustment lens 205 and the adjustment lens 206 for adjusting the beam waist position do not act, that is, in a state where the adjustment lens 205 and the adjustment lens 206 are in contact with each other. Is set to be the farthest point of the beam waist position adjustment range.

Adjustment lens 2 for adjusting beam waist position
By appropriately setting the distance between the lens 05 and the adjustment lens 206, the beam waist of the measurement illumination light beam can be adjusted on the object 10. When the various adjustments are completed, the light source 1, the frequency shifters 108 and 109
And the object 10 all form a conjugate relationship. Object 1
The two-dimensional diffraction pattern 12 on 0 is formed by a checkered lattice. The checkerboard has the same pitch d in the X and Y directions. The four measurement illumination light beams incident on the checkered grating on the object 10 are reflected by the checkered grating,
Diffracts. Now, focusing only on the first plane position measurement illumination light beam 114, the relationship between the incident angle θ and the X-direction diffraction angle θx and the Y-direction diffraction angle θy of the primary light diffracted light is given by the following equation.

Sin θx = ± λ / d (1) sin θy = sin θ ± λ / d (2) Specularly reflected light (zero-order diffraction light) of the first plane position measurement illumination light beam satisfying the expressions (1) and (2) 5) and FIG. 6 show the mapping of the first-order diffracted light. FIG. 5 shows that the first plane position measurement illumination light beam 114 is applied to the two-dimensional pattern 12 on the object 10 with respect to the normal line 12T of the two-dimensional pattern 12. This shows a state where light is incident at an angle θ. FIG. 6 shows a state in which four measurement illumination light beams 114 to 117 are incident on the two-dimensional pattern 12 on the object 10. 7 and 8
As shown in the figure, the first plane position measurement illumination light beam 114, the second plane position measurement illumination light beam 116, the first normal direction measurement illumination light beam 115, and the second normal direction measurement illumination light beam 117.
Are incident from directions rotated by a slight angle + α with respect to the normal to the object surface, so that the respective 0th order light,
The first-order diffracted light can be separated and extracted independently without overlapping with the 0th-order light and the first-order diffracted light of the other illumination light beams for measurement.

As for the incident angle, as shown in FIG. 8, the first plane position measuring illumination beam 114 and the second plane position measuring illumination beam 116 have an incident angle θ1 and the first normal direction measuring illumination beam. Reference numeral 115 denotes an incident angle θ2, and the illumination light flux 117 for the second normal direction measurement has an incident angle θ3.
The two-dimensional diffraction pattern 12 on 0 is irradiated. FIG.
Zero-order light and first-order diffracted light of the first plane position measurement illumination light beam 114 and the second plane position measurement illumination light beam 116, the first normal direction measurement light beam 115, and the second normal direction measurement light beam 117 Is the 0th-order light mapping. In the embodiment of the present invention, as shown in FIGS. 5, 6, and 9,
Since the diffracted light mapping is reflection diffraction, the positive direction of the X axis is the left direction in the figure, and the positive direction of the Y axis is the downward direction in the figure, which is different from a general coordinate system. .

As shown in FIGS. 10, 11 and 19, the light receiving optical system 400 is arranged to receive the diffracted light spreading from the reflection point on the two-dimensional pattern. But,
In an electron beam drawing apparatus or a stepper, a member 710 of a drawing optical system or a projection optical system occupies most of the space, and the space for the light receiving optical system is often limited. Therefore, an arrangement is required in which the diffraction angle that determines the size of the entire light receiving optical system can be made small, and an appropriate interval is maintained between the light receiving sections so that the diffracted light beams can be easily branched and superimposed on each other. Also, the space on the irradiation optical system side is limited by the members of the device, similarly to the light receiving optical system side. On the light receiving optical system side, the diffraction angle of the zero-order light in the Y direction is θ as in the incident angle. Referring to equation (2) for the diffraction angle θy of the first-order diffracted light in the Y direction, θy that satisfies the complex negative equation is a value smaller than θ. That is, since the -1st-order diffracted light appears on the member side of the apparatus such as the drawing optical system and the projection optical system with respect to the 0th-order light, it tends to be blocked by these members.

In this case, the passing position of the light beam on the light receiving optical system side and the irradiating optical system side is asymmetric, and if the -1st-order light is set so as not to be blocked by the original members of the apparatus, the incident angle is increased by the incident side. θ is made large and a dead zone is provided. When the incident angle θ is increased, the difference between the diffraction efficiencies of the polarization components (S-polarized light and P-polarized light) of the reflected diffracted light also increases,
It affects the superposition interference at the light receiving section. However, θy that satisfies the complex positive expression of Expression (2) is larger than θ, and the + 1st-order diffracted light appears on the object side with respect to the 0th-order light.
Therefore, if the 0th-order light is not blocked by the member, the + 1st-order light will not be blocked by the member 710 of the apparatus. Therefore, if the + 1st-order light is used, the incident angle θ can be set to the minimum value in a range not blocked by the member, and the difference in diffraction efficiency due to the polarization component can be reduced.

The first-order diffracted light that simultaneously satisfies the complex positive expression of the expression (2) and the expression (1) is a + 1st-order diffraction light in the X direction, a + 1st-order diffraction light in the Y direction, a −1st-order diffraction in the X direction, and a Y-direction. + 1st order diffracted light. These are adjacent quadrants ((X, Y)
Quadrant and (-X, Y) quadrant), and by using these light beams, it is possible to contribute to space saving of the light receiving side optical system. FIG. 14 shows a diffracted light mapping used for measurement in the X, Y, and Z directions of the diffracted light diffracted by the alignment mark. Here, f1 (0) is the 0th-order diffracted light after the first plane position measurement illumination light beam 114 is diffracted by the alignment mark, and f2 (0) is the second plane position measurement illumination light beam 116. This is the zero-order diffracted light after being diffracted by the alignment mark.

F1 (X, Y) is a + 1st order diffracted light in the X direction and a + 1st order in the Y direction after the first plane position measuring illumination light beam 114 is diffracted by the alignment mark. f1 (-
(X, Y) is a -1st-order diffracted light in the X direction and a + 1st-order diffracted light in the Y direction after the first plane position measurement illumination light beam 114 is diffracted by the alignment mark. f2 (X, Y) is a + 1st-order diffracted light in the X direction and a + 1st-order diffracted light in the Y direction after the second plane position measuring illumination light beam 116 is diffracted by the alignment mark. f2 (−X, Y) is the second plane position measurement illumination light flux 1
X direction after diffraction of 16 by the alignment mark is-
The first order is the + 1st order diffracted light in the Y direction. f1 ′ (0) is the 0th-order diffracted light after the first normal direction measurement illumination light flux 115 is diffracted by the alignment mark.

F2 '(0) is the 0th-order diffracted light after the second normal direction measuring illumination light beam 117 is diffracted by the alignment mark. Another method for reducing the size of the light receiving optical system is to reduce the diameter of the objective lens 410. In order to reduce the lens diameter, the difference between the diffraction angles of the zero-order light and the first-order light may be reduced. As a method of reducing the difference between the diffraction angles, there is a method of increasing the pitch of the two-dimensional diffraction pattern or decreasing the light source wavelength λ according to the expressions (1) and (2). Usually, the pitch of the diffraction pattern is about several μm to several tens μm. At this time, if a He-Ne laser light source of λ = 633 nm is used, the diffraction angle can be made sufficiently small. In addition, a resist is often applied on the surface of the object, but this wavelength is long enough not to expose the resist.

Further, the angle β between the optical axis of the objective lens 401 and the normal to the object is θ, the angle between the 0th-order light of the first illumination light beam and the normal to the object is θ, and +1 of the first illumination light beam. Order diffracted light Y
The diffraction angle in the direction is given by the following equation as θy. β = (θ + θy) / 2 This is an intermediate angle between the 0th-order light and the 1st-order diffracted light. By taking this optical axis, the lens diameter can be reduced even if it is located far from the object. Also, the longer the distance from the reflection point on the object to the objective lens, the wider the interval between each diffracted light,
There is also an advantage that branching of each diffracted light and superposition interference at the light receiving unit are facilitated. FIG. 10 shows an example of a light projecting optical system and a light receiving optical system. The wavelength λ is 633 nm, the first plane position measuring illumination beam 114 and the second plane position measuring illumination beam 116.
, The diffraction grating pitch d = 20 μm, the focal length of the irradiation lens 303 is 133 mm, and the focal length of the light receiving side objective lens is 220 mm.

Since the four illumination light beams incident on the irradiation lens 303 are parallel to each other and have an interval of 3 mm, this interval is approximately 5 mm after passing through the light receiving side objective lens 401. Regarding the diffraction angle of the primary light, θx = 1.8 ° and θy = 76.25 using Expressions (1) and (2).
°. The angle β of the optical axis of the light receiving side objective lens 401 is 7
At 3 °, the lens diameter becomes φ40 mm at this time, and four illumination light beams can be transmitted without colliding with the member 710. The light receiving side objective lens 401 is disposed at a position corresponding to one focal length from a reflection point on the object 10, and
It plays a role in parallelizing a large number of reflected diffracted lights spreading from a reflection point on zero. The diffracted lights made parallel to each other by the light receiving side objective lens 401 are reflected by the folding mirrors 402 and 4.
03 to the light receiving portion, and furthermore, the return mirror 40
According to 4, 405, the 0th-order light and the 1st-order light are contained in the same plane.

Next, details of the structure of the light receiving section 500 will be described with reference to FIG.
Shown in The light receiving unit includes a first plane position measurement illumination light beam 114 included in adjacent quadrants, here, (+ X, + Y) quadrants and (−X, + Y) quadrants, of the diffracted light received by the light receiving optical system 400. The plane including the target object is obtained from a combination of any one of a combination of high-order diffracted light and a zero-order light and a combination of high-order diffracted lights of the two-dimensional pattern of the second plane position measurement illumination light beam 116 with different frequencies. Forming an interference measurement signal for position measurement within the device. The interference measurement signal for position measurement in the X direction in the plane including the object is −1 order in the X direction and +1 in the Y direction among the diffracted light of the first plane position measurement illumination light beam 114 due to the two-dimensional pattern. Of the next diffracted light 512 and the diffracted light by the two-dimensional pattern of the second plane position measuring illumination light flux 116, the + 1st order in the X direction,
Beam splitter 5 applies + 1st order diffracted light 514 in the Y direction.
At 30, it is formed by overlapping. The X-position measurement interference signal is received by the photo sensor 550.

The interference measurement signal for position measurement in the Y direction in the plane including the object is +1 in the X direction in the diffracted light of the first plane position measurement illumination light beam 114 due to the two-dimensional pattern.
Next, the + 1st-order diffracted light 511 in the Y direction and the light beam branched from the 0th-order light 513 of the second plane position measurement illumination light beam 116 by the beam splitter 531 are combined with the beam splitter 5.
At 32, an overlap is formed. The Y position measurement interference measurement signal is received by the photo sensor 551. The first Z-direction position measurement interference measurement signal obtained when the normal direction of the plane including the target object, that is, the Z direction is irradiated at the irradiation angle θ2, is obtained from the zero-order light 513 of the second plane position measurement illumination light beam 116. The light beam split by the beam splitter 533 and the zero-order light 517 of the first normal direction measurement illumination light beam 115 are superposed and formed by the beam splitter 534. The Z position measurement interference signal is received by the photo sensor 552.

The second Z-direction position measurement interference measurement signal obtained when the normal direction of the plane including the object, that is, the Z direction is irradiated at the irradiation angle θ3, is the first plane position measurement illumination light beam 1.
A beam split by the beam splitter 535 from the sixteenth zero-order light 510 and the zero-order light 516 of the second normal direction measurement illumination light beam 115 are superimposed and formed by the beam splitter 536. The Z-position measuring interference signal is output from the photo sensor 55.
Light is received at 3. The light receiving unit further superimposes the 0th-order light 510 of the first plane position measurement illumination light beam 114 and the 0th order light 513 of the second plane position measurement illumination light beam by the beam splitter 538 via the mirror 537 to obtain the X position measurement. A reference signal for interference and a reference signal for Z position measurement are formed. The X-position measuring interference reference signal and the Z-position measuring interference reference signal are received by the photosensor 554.

The first plane position measuring illumination light beam 114 is also provided.
Of the two-dimensional pattern of the light beam branched from the zero-order light 510 by the beam splitter 539 and the two-dimensional pattern of the second plane position measurement illumination light beam 116, the -1 order diffraction in the X direction and the +1 order diffraction in the Y direction. Light 515 is split into beam splitter 540
To form an interference reference signal for Y position measurement.
The Y-position measurement interference reference signal is received by the photosensor 555. Each of the interference measurement signals and the interference reference signal is a superposition interference of two beams having slightly different frequencies, that is, a beat signal due to heterodyne interference. The frequency of the illumination light flux for the first plane position measurement and the illumination light flux for the first normal direction measurement (both are hereinafter referred to as “first measurement light flux”) is f
1. The frequency of the illumination light flux for the second plane position measurement and the illumination light flux for the second normal direction measurement (both are hereinafter referred to as “second measurement light flux”) is f2.

The complex amplitude of a certain diffracted light beam among a large number of diffracted light beams by the two-dimensional diffraction pattern of each light beam is represented by a1 = A1 * exp [-i (2πf1t + φ1)] a2 = A2 * exp [−i (2πf2t + φ2) )]. Where φ1 is the initial phase of the first illumination light flux,
φ2 is the initial phase of the second illumination light flux, and t is time. The intensity signal obtained by superimposing these light beams is given by I = A1 * A1 + A2 * A2 + 2A1 * A2 * cos
[2πΔft + (φ1−φ2)]. However, Δf = f1−f2.

This is a beat signal having a frequency Δf, and its phase component is φ1−φ2 (3). Attention is paid to the + 1st-order diffracted light in the X direction and the + 1st-order diffracted light in the Y direction among the many high-order diffracted lights of the first illumination light flux or the second illumination light flux by the two-dimensional pattern on the object. The object including the two-dimensional diffraction pattern is ΔX in the X direction and ΔY in the Y direction.
When displaced, the phase of the diffracted light changes by 2π (ΔX + ΔY) / d = φx + φy in both the first illumination light flux and the second illumination light flux. Here, d is the pitch of the two-dimensional diffraction pattern. Further, since the phase changes with respect to the movement of the object in the Z direction, the value is set to φz.

Therefore, if the object is in the X direction, the Y direction,
The phase change amount of the diffracted light when it changes in the direction is φx + φy + φz (4). In the case of a -1st order diffracted light in the X direction and a + 1st order diffracted light in the Y direction, the sign of φx changes, and the X direction, Y direction, Z
The amount of phase change with respect to the displacement in the direction is -φx + φy + φz (5). The phase of the zero-order light does not change with respect to the displacement of the object in the X and Y directions, but changes only with respect to the displacement in the Z direction. However, the illumination light flux for normal direction measurement among the first illumination light flux and the second illumination light flux has a different phase change amount with respect to the displacement ΔZ in the Z direction of the object due to a difference in the incident angle.

The phase change amount φz of the first illumination light beam with respect to the displacement of the object in the Z direction and the phase change amount φz ′ of the second illumination light beam with respect to the displacement of the object in the Z direction are as follows: φz = 4πΔZ / λ * cos θ1 (6) ) Φz ′ = 4πΔZ / λ * cos θ2 (7) The phase component of the X position measurement interference measurement signal is obtained by substituting equation (4) for φ1 in equation (3) and (5) for φ2.
By substituting the equation, (φx + φy + φz) − (− φx + φy + φz) = 2φx (8) The phase component of the X position measurement interference reference signal is
By substituting equation (6) into φ1 and φ2 in equation (3), φz−φz = 0 (9)

Therefore, the expression (8) of the X-position measurement interference measurement signal and the expression (9) of the X-position measurement interference reference signal equally include position information in the Y direction (0 in this case), and the expression (8) If the difference of the expression (9) is taken, the position information in the X direction on the plane including the object is obtained as 2φx. From the equations (4) and (6), the phase component of the Y position measurement interference measurement signal is (φx + φy + φz) −φz = φx + φy (10) The phase component of the interference reference signal for Y position measurement is
From the equations (5) and (6), φz − (− φx + φy + φz) = φx−φy (11)

Therefore, the equation (9) of the Y position measurement interference measurement signal and the equation (10) of the Y position measurement interference reference signal are expressed as follows.
If the position information in the X direction is equally included, and the difference between the expressions (9) and (10) is taken, the position information in the Y direction on the plane including the object is obtained as 2φy. Further, the phase component of the first Z position measurement interference measurement signal is given by: φz′−φz = 4π (cos θ2−cos θ1) / λ * ΔZ (12) from Expressions (6) and (7), and the second Z From the equations (6) and (7), the phase component of the position measurement interference measurement signal is given by φz′−φz = 4π (cos θ3−cos θ1) / λ * ΔZ (13), which is a value proportional to ΔZ. is there.

The phase component of the Z position measurement interference reference signal (also X position measurement interference reference signal) is 0 according to equation (9). Therefore, by taking the difference between Equations (12) and (9),
The position information in the Z direction (the direction of the normal to the plane including the object) is directly obtained as Expression (12). Phase difference Φz1 between the first Z position measurement interference signal and the Z position measurement interference reference signal
(ΔZ) and the phase difference Φz2 (ΔZ) between the second Z position measurement interference signal and the Z position measurement interference reference signal are given by the following expressions (12) and (13): Φz1 (ΔZ) = 4π (cos θ1) −cos θ2) / λ
* ΔZ Φz2 (ΔZ) = 4π (cos θ1-cos θ3) / λ
* ΔZ. Here, the Z position measurement interference signal is subtracted from the Z position measurement interference reference signal (that is, the sign in parentheses is inverted).

Now, let us say that the detection stroke of the first Z position measurement interference signal is Z1, and the detection stroke of the second Z position measurement interference signal is Z2 (Z1> Z2). When ΔZ = Z1, Φz1 (ΔZ) = 2π, and when ΔZ = Z2, Φz2 (ΔZ) = 2π, Φz1 (ΔZ) = 2π / Z1 * ΔZ (a) Φz2 (ΔZ) = 2π / Z2 * ΔZ (B). In the waveform on the left side of FIG. 13, the solid line indicates the signal of equation (a), and the dotted line indicates the signal of equation (b). Φ
Taking the difference between z2 (ΔZ) and Φz1 (ΔZ), that is, the difference between equations (b) and (a), ΔΦ (ΔZ) = 2π (1 / Z2-1 / Z1) * ΔZ = 2π (Z1- Z2) / (Z1 * Z2) * ΔZ (c)

Comparing the expressions (a), (b) and (c), the expression (c) shows that the detection stroke is Z1 * Z2 / (Z
1-Z2) can be considered to represent the Z position measurement interference signal. The signal of equation (c) is shown as a waveform on the right side of FIG. From the equation, θ2 = 70.39 °, θ
If 3 = 70.48 °, Z1 = 50 μm, Z2 =
It becomes 40 μm. Substituting these into equation (c) gives ΔΦ (ΔZ) = 2π / 200 μm * ΔZ. Therefore, an interference signal for Z position measurement having a stroke of 200 μm is obtained. At this time, the number of samples is 2000 when the stroke is 50 μm and the resolution is 25 nm.
be equivalent to. That is, the resolution is 25 nm and the number of samples is 20
The detection stroke, that is, the detectable range can be expanded to 200 μm as it is at 00.

Now, for the sake of convenience, the position reference interference reference signal in each direction is expressed by equation (9) in the X direction, equation (11) in the Y direction, and Z
The direction is defined by equation (9).
Even if the direction is the expression (10) and the Z direction is the expression (12), position information in each direction can be obtained only by reversing the sign. From equation (13), the incident angle θ2 of the first normal direction measurement illumination light beam for obtaining the desired Z detection stroke is obtained.
For example, when it is desired to obtain a detection stroke of 50 μm in equation (12), 2π is substituted for the left side and 50 μm is substituted for ΔZ on the right side. However, since the value of θ2 is larger than θ1, that is, the value of θ2 is desired to be closer to the object than the first illumination light beam, the second value
When the first Z position measurement interference reference signal is subtracted from the Z position measurement interference reference signal, 2π = 4π (cos 70 ° −cos θ2) / 633 nm
× 50 μm From this, θ2 = 70.39 ° is obtained.

The signal processing section 600 obtains the positions in the plane including the object and the normal direction of the plane including the object based on the phase of the interference measurement signal for position measurement. The position measurement interference measurement signal in the X direction is received by the photo sensor 550, and the X position measurement interference reference signal is received by the photo sensor 554. The phase difference between the signals received by the photosensors 550 and 554 is measured by the phase meter 610. The Y position measurement interference measurement signal is received by the photo sensor 551, and the Y position measurement interference reference signal is received by the photo sensor 555. The phase difference between the photosensor 551 and the signal received by the photosensor 555 is measured by the phase meter 611. The first Z-direction position measurement interference measurement signal is received by the photo sensor 552, and the Z position measurement reference signal is received by the photo sensor 554.

The phase difference between the signal received by the photosensor 552 and the signal received by the photosensor 554 is determined by a phase meter 61.
Measure at 2. The second Z-direction position measurement signal is received by the photo sensor 553, and the Z-direction position measurement reference signal is received by the photo sensor 554. The phase difference between the signal received by the photo sensor 553 and the signal received by the photo sensor 554 is measured by the phase meter 613. The arithmetic processing unit 620 obtains the position in the X direction in the plane including the object based on the phase difference of the phase meter 610, and calculates the position in the Y direction in the plane including the object based on the phase difference of the phase meter 611, And the phase meter 6
The position in the Z direction in the plane including the object is obtained based on the phase difference between 12 and 613. The arithmetic processing unit 620 can independently measure displacement components in each direction with respect to the XYZ displacement of the object, thereby performing various controls including positioning of the object. [4] Application of the Position Measuring Device of the Present Invention The position measuring device of the present invention is capable of accurately aligning an object such as a charged particle beam device such as an electron beam lithography device and a semiconductor exposure device. Can be applied to devices that require

Here, an electron beam drawing apparatus will be described as an example. Referring to FIG. 15, an electron beam writing apparatus includes an electron optical system 730 including an electron gun for generating an electron beam, an X-direction scanning electrode and a Y-direction scanning electrode for changing the direction of an electron beam, and A drawing object 732 arranged in a chamber in a vacuum state can be placed,
A stage 734 that is movable in the X and Y directions and the Z direction that is the normal direction in the horizontal plane. Then, the illumination optical system 100 and the correction optical system 2 of the position measuring device of the present invention.
Illumination-side optical housing 740 including 00 and illumination optical system 300
Then, the light receiving side optical housing 742 including the light receiving optical system 400 is arranged on both sides of the stage 734. Illumination side optical housing 740
The optical housing 742 on the light receiving side is arranged so as to avoid the mounting position of each component of the electron beam drawing apparatus such as the electron optical system 730 and the maximum operation range thereof. Then, the light is irradiated from the illumination side optical housing 740 and the light receiving side optical housing 742 is irradiated.
The illumination-side optical housing 740 and the light-receiving side so that the light beam incident on the illumination optical system 730 can pass through the mounting position of each component of the electron beam writing apparatus such as the electron optical system 730 and the maximum operating range thereof. The optical housing 742 is arranged.

In an electron beam lithography apparatus, an electron optical system and a stage perform a predetermined operation in accordance with various signals from a control circuit, and form a predetermined pattern on a mask or a wafer to be a drawing object by an electron beam. Things. Specifically, an electron beam drawing apparatus to which the position measuring device of the present invention is applied can process a semiconductor manufacturing mask such as an encoder pattern and a phase shift mask. Further, a semiconductor wafer and a mask for manufacturing a semiconductor can be processed by a semiconductor exposure apparatus to which the position measuring device of the present invention is applied.

[0053]

【The invention's effect】

(1) According to the present invention, a light beam shift unit for translating a plurality of measurement illumination light beams received from an illumination optical system and a beam waist position changing unit for changing a beam waist position of the plurality of measurement illumination light beams. By arranging a correction optical system with a laser beam, the measurement illuminating light beam is appropriately irradiated to the alignment pattern, and the measurement is performed so that the beam waist position matches the measurement pattern position. The illumination light flux can be adjusted. (2) According to the present invention, a semiconductor exposure apparatus to which a small and high-performance position measuring apparatus is applied can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an optical system according to an embodiment of a position measuring device of the present invention.

FIG. 2 is a perspective view showing an adjustment optical system and an irradiation optical system according to the embodiment of the position measuring device of the present invention.

FIG. 3 is a plan view showing an adjustment optical system and an irradiation optical system according to the embodiment of the position measuring device of the present invention.

FIG. 4 is a side view showing an adjustment optical system and an irradiation optical system according to the embodiment of the position measuring device of the present invention.

FIG. 5 is a diffraction light mapping of a first plane position measurement illumination light beam based on a two-dimensional diffraction pattern on an object in the embodiment of the position measurement device of the present invention.

FIG. 6 is a perspective view showing a state in which a measurement illumination light beam is incident on a two-dimensional diffraction pattern on an object in the embodiment of the position measuring device of the present invention.

FIG. 7 is a plan view showing a state in which a measurement illumination light beam is incident on a two-dimensional diffraction pattern on an object in the embodiment of the position measurement device of the present invention.

FIG. 8 is a side view showing a state in which a measurement illumination light beam is incident on a two-dimensional diffraction pattern on an object in the embodiment of the position measuring device of the present invention.

FIG. 9 is a diffraction light mapping of an illumination light beam for measuring a planar position and an illumination light beam for measuring a normal direction by a two-dimensional diffraction pattern on an object in the embodiment of the position measuring device of the present invention.

FIG. 10 is a side view showing a positional relationship between an illumination light beam for measuring a planar position, an illumination light beam for measuring a normal direction, and its diffracted light and an apparatus member in the embodiment of the position measurement device of the present invention.

FIG. 11 is a plan view showing a positional relationship between an illumination light beam for measuring a plane position, an illumination light beam for measuring a normal direction, and its diffracted light in the embodiment of the position measurement device of the present invention and a device member.

FIG. 12 is a schematic block diagram illustrating a configuration of a light receiving optical system according to an embodiment of the position measuring device of the present invention.

FIG. 13 is a signal waveform diagram of the embodiment of the position measuring device of the present invention.

FIG. 14 shows X, Y, and X of the diffracted light diffracted by the alignment mark in the embodiment of the position measuring device of the present invention.
It is a diffracted light mapping used for the measurement in the Z direction.

FIG. 15 is a schematic partial cross-sectional view of an embodiment of an electron beam writing apparatus to which the position measuring device of the present invention is applied.

FIG. 16 is a partially enlarged view of a portion of the illumination optical system of FIG. 1 according to the embodiment of the position measuring device of the present invention.

FIG. 17 is a partially enlarged view of a portion of the object in FIG. 1 according to the embodiment of the position measuring device of the present invention.

18 is a partially enlarged view of a part of the light receiving optical system of FIG. 1 according to the embodiment of the position measuring device of the present invention.

FIG. 19 shows an embodiment of the position measuring device according to the present invention.
It is the elements on larger scale of the target object part.

[Explanation of symbols]

Reference Signs List 1 light source 10 object 12 two-dimensional diffraction pattern 100 illumination optical system 102 relay lens 103 beam splitter 104 first illumination light beam 105 second illumination light beam 106, 107 relay lens 108 first frequency shifter 109 second frequency shifter 110 for first measurement Illumination beam 111 Second measurement illumination beam 112, 113 Beam splitter 114 First plane position measurement illumination beam 115 First normal direction measurement illumination beam 116 Second plane position measurement illumination beam 117 Second normal direction measurement Illumination light beam 200 Correction optical system 201, 202 Parallel plane plate 203, 204 Wedge prism 205, 206 Focus lens 300 Irradiation optical system 301, 302 Folding mirror 303 Irradiation lens 400 Light receiving optical system 401 Light receiving side objective lens 402-405 Fold Return mirror 500 Light receiving unit 512 (-1, +1) of the illumination light beam for the first plane position measurement
Order diffracted light 514 (+1, +1) of the illumination light flux for the second plane position measurement
Order diffracted light 515 (−1, +1) of the illumination light flux for the second plane position measurement
Order diffracted light 511 (+1, +1) of the illumination light flux for the first plane position measurement
Order diffracted light 510 0th-order light of first plane position measurement illumination light beam 513 0th order light of second plane position measurement illumination light beam 517 0th order light of first normal direction measurement illumination light beam 516 Second direction measurement 0th-order light of illumination light beam 550 to 555 Photosensor 600 Signal processing unit 610 Phase meter (X) 611 Phase meter (Y) 612 Phase meter (Z1) 613 Phase meter (Z2) 620 Operation processing unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Suzuki et al. 75-1, Hasunuma-cho, Itabashi-ku, Tokyo Inside Topcon Corporation (72) Inventor Kazuo Abe 75-1, Hasunuma-cho, Itabashi-ku, Tokyo Topcon Corporation (72) Inventor Tohru Tojo 1 Kosuka Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Prefecture Inside Toshiba R & D Center (72) Inventor Ryoichi Hirano 1-Koshiko Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock Company Toshiba R & D Center

Claims (6)

[Claims] An illumination optical system that has a light beam splitting unit that separates a light beam from a light source unit that emits a coherent light beam into a plurality of measurement illumination light beams, and that makes the plurality of measurement illumination light beams parallel. A portion for making the plurality of measurement illumination light beams received from the illumination optical system parallel, and a light beam shift for translating the plurality of measurement illumination light beams in the parallel portion; A correction optical system in which a beam waist position changing unit that changes a beam waist position of the illumination light flux for measurement and a plurality of illumination light fluxes for measurement are provided on an object whose position is to be measured. An irradiation optical system that irradiates the positioning pattern, and a light receiving optical system that receives diffracted light from the positioning pattern irradiated with the plurality of measurement illumination light beams by the irradiation optical system, A light receiving unit that receives the diffracted light received by the light receiving optical system and forms a measurement interference signal; and a signal processing unit that measures the position of the target object based on the phase of the measurement interference signal. Position measuring device. 2. The light beam shift unit includes at least a pair of prisms provided so as to be rotatable about an optical axis, and adjusts a moving distance of an irradiation position by changing a crossing angle of the prisms. Prism crossing angle 2
2. The position measuring device according to claim 1, wherein the moving direction of the irradiation position of the measurement illumination light beam is adjusted by changing the direction of an equal line. 3. The beam waist position changing unit includes at least a convex lens and a concave lens, and changes a beam waist position of the plurality of measurement illumination light beams by changing an interval between the convex lens and the concave lens. The position measuring device according to claim 2, wherein the position measuring device is configured as follows. 4. The illumination optical system according to claim 1, wherein the first measurement illumination light beam and the second measurement illumination light beam emitted at a first incident angle are irradiated with a second incident angle different from the first incident angle. A first measuring illumination light beam, a second measuring illumination light beam, and a third measuring illumination light beam. The correction optical system receives the first measurement illumination light beam, the second measurement illumination light beam, and the third measurement illumination light beam. The illumination light flux for measurement and the illumination light flux for second measurement are arranged, the illumination light flux for third measurement is arranged at a peripheral position more than these, and the third illumination light flux for measurement in the correction optical system is placed in the optical path of the illumination light flux for third measurement. 3. A parallel flat plate having a rotation axis in a direction orthogonal to the optical axis so as to change an incident angle at which the three-dimensional illumination light beam irradiates the two-dimensional pattern, wherein: Any one of 3
The position measuring device according to the paragraph. 5. The illumination optical system includes: a first measurement illumination light beam having a first frequency from a coherent light beam emitted by the light source unit; and a second measurement illumination light beam having a second frequency different from the first frequency. And the first measurement illumination light beam are separated to form a first plane position measurement light beam and a first normal direction measurement illumination light beam, and the second measurement illumination light beam is separated to form a second measurement illumination light beam. Two plane position measuring light beam and second
A light beam separation unit that forms a normal direction measurement illumination light beam; the irradiation optical system emits a two-dimensional pattern as a positioning pattern; and the light reception optical system includes a first measurement illumination light beam. The light receiving unit is configured to receive a combination of diffracted lights having different frequencies in any one of a combination of a high-order diffracted light and a zero-order diffracted light and a combination of the high-order diffracted lights according to the two-dimensional pattern of the second measurement illumination light beam. Is a combination of a diffracted light having a frequency different from any one of a combination of a high-order diffracted light and a zero-order diffracted light and a combination of the high-order diffracted lights according to the two-dimensional pattern of the first measurement illumination light flux and the second measurement illumination light flux. Forming a plane position measurement interference signal for performing position measurement within a plane provided with the two-dimensional pattern of the object, the first measurement illumination light beam or the second measurement light beam; It is configured to form a normal position measurement interference signal for performing position measurement in the normal direction of the object from a combination of the 0th-order diffracted light of the illumination light beam and the 0th-order diffracted light of the third measurement illumination light beam, The signal processing unit performs position measurement in the plane direction of the object based on the phase of the interference signal for plane position measurement, and performs position measurement in the normal direction of the object based on the phase of the interference signal for normal direction measurement. The position measuring device according to claim 4, wherein the position measuring device is configured as follows. 6. An electron beam lithography apparatus, wherein the components of the electron beam lithography apparatus are arranged so as to avoid mounting positions and their maximum operating ranges.
The position measuring device according to any one of claims 1 to 5, wherein the position measuring device irradiates a position measuring light beam for measuring a position of the object, an illumination-side optical member, and the object. A light receiving side optical member for receiving the reflected diffracted light from and measuring the position of the object, and a light beam emitted from the illumination side optical member and incident on the light receiving side optical member, The illumination-side optical member and the light-receiving-side optical member are arranged in the electron beam lithography apparatus so that the component parts of the electron beam lithography apparatus can be transmitted through the mounting position and their maximum operation range. An electron beam drawing apparatus characterized by the above-mentioned.