JPH0635924B2 - Position detecting method, apparatus therefor and position aligning apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention uses a position detection method and device using optical heterodyne interference light in semiconductor ultrafine processing, ultraprecision measurement, and the like, and further uses the position detection configuration. The present invention relates to an alignment device that performs ultra-precision alignment of two objects.

[Conventional technology]

A precise position detecting technique such as an aligner for synchrotron radiation photolithography or a photostepper is disclosed in, for example, JP-A-62-62.
Optical heterodyne position detection methods such as No. 261003 have begun to be put to practical use at the prototype level.

FIG. 7 shows the outline of the position detecting means utilizing the interference diffracted light shown in the above-mentioned prior art. First, the device configuration is such that a mask A and a second object which are the first object are provided. Each diffraction grating (1a) (1b) formed on the wafer B
The diffraction grating (1a) (by adjusting the direction of the light separated by a light source (2) composed of a laser device that generates two slightly different frequencies of orthogonal linearly polarized light and a polarization beam splitter (40a) described later. A mirror that irradiates from a direction having an angle of ± θn with respect to the lattice plane normal of 1b) [θn satisfies the equation of diffraction n · λ = P · sin θn (λ is the light source wavelength, n is a positive integer)] (42a) and (43a) incident angle adjusting means, a polarization beam splitter (40a) for separating two polarized lights coming from the light source (2) and branching them into the mirrors (42a) and (43a) respectively, and the diffraction grating.
(1a) (1b) to interfere with each other diffracted light in the vertical direction to make interference light, the optical interference means consisting of polarizing plates (56) (57), and these polarizing plates (56) (57) Detected by the detector (60a) (62a) for detecting the beat signal generated by the detector, and the phase shift of the beat signal detected by each of the detectors (60a) (62a) is detected and displayed on the phase meter. And a signal processing means (70).

The light emitted from the light source (2) has two frequency components f
₁ and f ₂ are separated by a polarization beam splitter (40a) into light of frequency component of f ₁ and light of frequency component of f ₂ , and the diffraction grating (1a) is separated by mirrors (42a) and (43a), respectively. Incident from (1b) from ± nth direction (for example, ± first order).
Lights f ₁ and f diffracted in the vertical direction from the diffraction gratings (1a) and (1b)
₂ (indicated by a broken line in the figure) passes through the mirror (38) and the prism mirror (39) to cause interference in each polarizing plate (56) (57), and the beat signals are detected by the detectors (60a) (62a) respectively. To be done. Between the beat signals detected by the detectors (60a) and (62a), a phase difference proportional to the amount of displacement of the diffraction gratings (1a) and (1b) occurs. By detecting this phase difference with the phase meter of the signal processing means (70), the relative positional deviation amount between the two diffraction gratings (1a) and (1b) can be known.

[Problems to be solved by the invention]

In the above optical heterodyne position detection method, each diffraction grating (1
a) The signal detection range becomes wider as the absolute value n of the order in the ± nth irradiation direction of light with respect to (1b) increases, and the relationship between them is: signal detection range = diffraction grating (1a) (1b) pitch P / 2n, where n is 1, 1/2 of the pitch P
Is the detection range. However, the opposite relationship is true for the detection resolution, and unless the grating pitch P is reduced, the smaller the absolute value n of the order, the lower the resolution. Therefore, if the irradiation angle of the light to each diffraction grating (1a) (1b) is changed to increase the detection resolution and the absolute value n of the following is increased, the signal detection range becomes extremely narrower than the above expression.
(It should be noted that, even when the detection pitch is increased by decreasing the grating pitch P, similar results are obtained from the above equation).

Therefore, when trying to obtain higher position detection resolution by using such an optical heterodyne position detection method in an aligner for synchrotron radiation lithography whose transfer line width is on the order of quarter micron, the signal detection range becomes very narrow, It was difficult to put it into practical use.

The present invention was devised in view of the above problems of the prior art, and is a position detection method and device capable of expanding the detection range while maintaining the necessary detection resolution, and position adjustment using the position detection configuration. It is intended to provide a device.

[Means for solving problems]

Therefore, according to the position detecting method of the present invention, the absolute value n of the order is ± n for the ± nth irradiation direction of the coherent light with which the diffraction gratings provided on the first object and the second object such as the mask and the wafer are irradiated. Each of these diffraction gratings is irradiated with the coherent light from a plurality of different irradiation directions, and these irradiations interfere with the diffracted light generated in the vertical direction from the first and second diffraction gratings, respectively, and are generated thereby. Each beat signal is detected, and a beat signal finally generated from interference diffracted light having the same absolute value n of the irradiation direction order out of diffracted light extracted in the vertical direction as a result of irradiation of coherent light from the ± nth order The respective phase differences are measured, and the displacement amounts of the first and second objects (in addition to the relative positional displacement amount, other reference beat signals are generated based on the respective phase differences). (Absolute positional deviation amount that knows the displacement amount of each of the two objects) may be detected.

For example, the pitch P of the diffraction gratings provided on the first and second objects is set to be relatively large, and the linear diffraction of the orthogonal linearly polarized light from the ± 1st order and ± 4th order is smaller than those of the following diffraction gratings. Are irradiated with light having _two different frequency components f ₁ and f ₂ , and the
Each of the diffracted light from the object and the diffracted light from the first and second objects derived from the ± 4th irradiation directions are further separated, and the two frequency components f ₁ and f ₂ of these diffracted lights are interfered with each other. At the very least, each beat signal is generated. Then, if the phase difference between the beat signals due to the diffracted light from the first and second objects derived from the ± first-order irradiation directions is detected, the signal waveform is linear with a cycle of 1/2 of the diffraction grating pitch P. Become a signal. On the other hand, if the phase difference between the beat signals due to the diffracted light from the first and second objects originating from the ± 4th order irradiation directions is detected, a linear signal with a period of 1/8 of the diffraction grating pitch P is detected. Becomes In this way, the latter has a signal detection range of 1/4 that of the former.
However, the signal detection resolution is four times that.
Therefore, if the two phase differences are obtained at the same time, the displacement amount can be measured within the range of 1/2 of the grating pitch P, and the resolution of the diffracted light derived from the ± 4th order irradiation directions can be achieved at the same time.

Further, another method for detecting the amount of displacement of the first and second objects, which is not disclosed in the above-mentioned prior art (± n-order diffracted light among the diffracted light emitted from the light source and generated from the first and second diffraction gratings, respectively) The present invention can also be applied to a method of interfering with each other, detecting the beat signals generated thereby, and detecting the displacement amount by measuring the phase difference between these beat signals). In this case,
With respect to the diffracted light extracted in the nth diffraction direction, it is extracted in a plurality of diffraction directions having different absolute values n with respect to the diffraction orders and further interfered with each other to detect the interference light which has become a beat signal. By this detection, the phase differences between the beat signals finally generated from those having the same absolute value n of the orders of the ± n-order diffracted light are measured, and the displacements of the first and second objects are measured based on these respective phase differences. The amount will be detected. Also, irradiation may be performed from a plurality of irradiation directions in which the absolute values of the irradiation orders and the diffraction orders have three or more different values, or the diffracted light may be extracted and detected from such a plurality of diffraction directions. Needless to say.

In the configuration of the present invention described above, as a means for causing light interference, there is also a method of using a combination of the polarizing beam splitter and the polarizing plate as described above, but the polarizing beam splitter and the 1/2 wavelength plate are combined. It is also possible to use a beam splitter, a half wave plate and a polarizing plate in combination. That is, when irradiating the coherent light from the ± n-order directions, the + n-order light having only the f ₁ component extracted by the polarization beam splitter or both the f ₁ and f ₂ components extracted by the beam splitter is the same. Having only the f ₂ component extracted by the polarization beam splitter or both f ₂ and f ₁ components extracted by the beam splitter, one polarization plane of the −n-order light is shifted by 90 ° with a 1/2 wavelength plate for each diffraction It is also possible to irradiate the grating and cause interference at the time of diffraction (in the latter case where irradiation interference is made in a form having both components of f ₁ and f ₂ , _one of the interference light in the horizontal direction or the vertical direction). Is further cut by a polarizing plate to detect the remaining interference light), and the coherent light is made incident vertically on each diffraction grating, and the ± nth order diffracted light is extracted from the diffracted light generated from it. If the + n of order diffracted light or -n-order diffracted light, while the treated similarly with half-wave plate, it is also possible that allowed to interfere before the time of detection of ± n order diffracted light.

Next, the position detecting devices of the second and third inventions are related to the device for executing the position detecting method of the first invention, the second invention device is a structure for extracting diffracted light in the vertical direction, and the third invention device is a diffraction device. This is a configuration for extracting light in the ± n-order diffraction directions.
That is, the second invention device includes a first diffraction grating provided on the first object, a second diffraction grating provided on the second object, and a light source for generating coherent light of two slightly different frequencies, Incident angle adjusting means for making coherent light generated from the light source incident on the first and second diffraction gratings from the ± nth order, and at the time when the irradiation light is diffracted by each diffraction grating or each diffraction Optical interference means for generating a beat signal by interfering two frequency components in the optical paths of the diffracted light respectively extracted from the grating in the vertical direction, and the optical interference means extracted from the first and second diffraction gratings in the vertical direction, respectively. Detection means for detecting the beat signals generated by the interference means,
In a position detecting device having signal processing means for measuring the phase difference from these beat signals and detecting the displacement amount of the first and second objects based on this phase difference, each diffraction grating by the incident angle adjusting means With respect to the irradiation of coherent light from the ± n-th order with respect to, it is possible to respectively irradiate each of these diffraction gratings from a plurality of directions having different absolute values n of the order, and the detection means also corresponds to these irradiation directions. To be able to detect each beat signal,
Furthermore, regarding the signal processing means, beat signals finally generated from diffracted light having the same absolute value n of the irradiation direction order among diffracted light extracted in the vertical direction as a result of irradiation of coherent light from the ± nth order. The basic feature is that the phase differences of the first and second objects are detected based on the respective phase differences. Further, in the third invention device, since the light is incident in the vertical direction and the diffracted light is extracted in the ± n-order diffraction directions, there is no incident angle adjusting means unlike the second invention device, and each diffraction grating is used. A device provided with diffracted light extraction means such as a mirror and a polarization beam splitter for extracting ± n-order diffracted light from the generated diffracted light, and for the optical interference means, an apparatus for interfering two frequency components in the optical path of the diffracted light extraction. It is configured. Then, based on these configurations, the third invention takes out the diffracted light extracted from each diffraction grating in the ± n-order diffracting directions by the diffracted light extracting means in a plurality of diffracting directions having different absolute values n of the diffraction orders. Along with the detection means, each beat signal can be detected in correspondence with the diffracted light extraction direction. Further, the signal processing means also has an order of each diffracted light detected as a beat signal by the detection means. The phase differences between the beat signals finally generated from those having the same absolute value n are measured, and the displacement amounts of the first and second objects are detected based on the respective phase differences.

Further, the positioning device of the fourth and fifth inventions is based on the position detecting device of the second and third inventions, and further has a device configuration such that the first object and the second object can be positioned. It is a development and improvement, and the structure unique to the development includes a moving mechanism for moving the first object and / or the second object, and the position of the first object and the second object based on the measured phase difference. Signal processing control means for outputting a control signal to the moving mechanism based on the phase difference and moving the first object and / or the second object for alignment, rather than simply including signal processing means for detecting The other configurations are the same as the configurations of the second invention and the third invention.

〔Example〕

Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the first part of the synchrotron radiation exposure apparatus.
FIG. 3 is a schematic view of the arrangement of the alignment apparatus according to the fifth aspect of the present invention used for aligning the mask A as the object and the wafer B as the second object. Stage (8a) and wafer stage (8b)
, And other components are omitted.

In this embodiment, the mask diffraction grating (1a) and the wafer diffraction grating (1b) provided on the mask A and the wafer B, and both diffraction gratings (1a) via the cylinder lens (20) and the mirror (21). (1
Light source (2) consisting of a transverse Zeeman laser that irradiates laser light (two-frequency coherent light) perpendicular to b)
And a moving mechanism showing only the mask stage (8a) and the wafer stage (8b), and both diffraction gratings (1
Mirrors (30) and (31) for extracting ± 1st-order diffracted light and a mirror (32) for extracting ± 4th-order diffracted light among diffracted light generated from a) and (1b)
-1 with the diffracted light extraction means of (33) and the mirrors (31) and (33)
The polarization planes of the diffracted light extracted in the second and fourth order are
1/2 wave plate (50) (51) and the mirror (30) (3)
The + 1st-order diffracted light and the + 4th-order diffracted light extracted in 2) are
Optical interference means consisting of polarization beam splitters (52) and (53) that interfere with the -1st-order diffracted light and the -4th-order diffracted light whose polarization planes are shifted by 0 ° and are polarized there, and a mask diffraction grating (1a). ) Side is taken out ± 1st order and ± 4
First-order mask for detecting beat signals derived from ± 1st-order diffracted light and beat signals derived from ± 4th-order diffracted light, which are received by reflecting the interference light of the second-order diffracted light by knife edge mirrors (34) (35) The photodetector (60), the mask fourth-order photodetector (61), and the ± 1st and ± 4th-order diffracted light extracted from the wafer diffraction grating (1b) side are received, and ± 1 generated from the interference light is received. Beat signal from the 4th order diffracted light and ± 4
± 1 next time is input by inputting the detection means including the wafer first-order photodetector (62) and the wafer fourth-order photodetector (63) for detecting the beat signal derived from the second-order diffracted light and the beat signal detected by each of these detection means. A signal processing control circuit (7) that measures the phase difference between the beat signals originating from the folded light and the phase difference between the beat signals originating from the ± 4th order diffracted light, and outputs a control signal to the moving mechanism based on these phase differences. ) And have.

In the above device configuration, the mask diffraction grating (1a) and the wafer diffraction grating (1b) are slightly displaced in the grating longitudinal direction.
Further, a light transmission window (1c) is provided on the surface of the mask A. The irradiation of the coherent light to the wafer diffraction grating (1b) and the extraction of the diffracted light from the diffraction grating (1b) are performed by this light transmission window.
This is done via (1c). Further, the signal processing control circuit
A phase meter (not shown) that displays each measured phase difference is also installed at (7).

A method of using the above device configuration will be described below.

The transverse Zeeman laser of the light source (2) has a two-frequency component f ₁ ,
Light including f ₂ is generated, and this coherent light is applied to the mask diffraction grating (1a) and the wafer diffraction grating (1b) from the vertical direction. At this time, the wafer diffraction grating (1b) is irradiated through the light transmission window (1c). This irradiation produces diffracted light in both directions on both diffraction gratings (1a) and (1b) as shown in FIG.
At (30) and (31), the ± 4th order diffracted light is reflected by the mirrors (32) and (33) in the direction of the polarization beam splitters (52) and (53), and a part of the reflected light is knife edge mirrors (34) and (35). To the mask primary photodetector (60) and the mask quaternary photodetector (61) via
The rest reaches the wafer primary photodetector (62) and the wafer quaternary photodetector (63) and is received there. Of the diffracted light, it was reflected by the mirrors (31) (33) -1
The 1st and 2nd order diffracted light and the −4th order diffracted light are on the way.
Because the plane of polarization is shifted by 90 degrees (vertical component is horizontal and horizontal component is vertical) by 1), the polarized beam splitters (52) and (53) interfere with + first-order diffracted light and + 4th-order diffracted light, respectively. It becomes an interference light. Therefore, the detectors (60) (61) (62) (63) detect the beat signals generated by the interference light and send the beat signals to the signal processing control circuit (7). In the circuit (7), the phase difference between the beat signal sent from the mask primary photodetector (60) and the beat signal sent from the wafer primary photodetector (62) is measured, and FIG. The signal waveform as shown in a) will be obtained. Similarly, the signal processing control circuit (7) measures the phase difference between the beat signal sent from the mask quaternary photodetector (61) and the beat signal sent from the wafer quaternary photodetector (63). A signal waveform as shown in FIG. The signal waveform shown in FIG. 3 (a) is a linear signal having a period of the diffraction grating 1/2 pitch, and that of FIG. 3 (b) is a linear signal having a period of the diffraction grating 1/8 pitch. . In this way the signal processing control circuit (7)
Then, the phase difference of the beat signal derived from ± 1st order diffracted light and ± 4
Since the phase difference of the beat signal derived from the second-order diffracted light is detected, the relative positional deviation amount between the mask A and the wafer B can be measured within the range of the diffraction grating 1/2 pitch, and the resolution of the ± 4th-order diffracted light is measured. [If the phase meter resolution is about 1 °, the resolution will be (P / 8) / 360 °, ± 1
4 times the resolution of the next-order diffracted light].

FIG. 4 also shows an embodiment of the alignment apparatus of the fourth invention used for aligning the mask A and the wafer B of the synchrotron radiation exposure apparatus.

In the device configuration of this embodiment, coherent light having two frequency components f ₁ and f ₂ emitted from the light source (2) of the transverse Zeeman laser is partially reflected by the half mirror (22) toward the polarization beam splitter (40). Also, the rest is made to enter the side of another polarization beam splitter (41) through the mirror (23), and both polarization beam splitters (40) and (41) respectively have the above-mentioned coherent light with f ₁ component and f ₂ component. The light is separated into light, and the mirrors (42) (43) and mirrors (44) (45) respectively separate the mask diffraction grating (1a) and the wafer diffraction grating (1b) from the ± 1st order and ± 4th order directions, respectively. Irradiate. At this time, as shown in FIG. 5, the light of the f ₁ component has a polarization plane of 90 degrees by the half-wave plates (50) and (51).
Shifted by the mirrors (42) and (44), each diffraction grating (1a) (1b)
On the other hand, the light is emitted from the + 1st order and + 4th order. Further, in this embodiment, the diffracted light generated by irradiation from the ± first-order directions and the ±
Since all the diffracted light generated by irradiation from the fourth order is generated in the vertical direction and overlaps each other, as shown in FIG. 6 showing a state just from the side of FIG. 5, ± 1
By irradiating the second direction irradiation and the ± 4th order irradiation at different angles, the diffracted light can be extracted in the direction corresponding to the oblique incident angle (oblique detection is possible). There is.

The light emitted as described above becomes optical heterodyne interference light when diffracted by the diffraction gratings (1a) and (1b).
6) (37) and knife edge mirrors (34) (35) through mask primary photodetector (60) and wafer primary photodetector (62)
And the mask quaternary photodetector (61) and the wafer quaternary photodetector (63) are detected as beat signals, respectively.

Further, each detected beat signal is input to the signal processing control circuit (7), and the phase difference of the beat signal derived from the ± 1st order irradiation light and the phase difference of the beat signal derived from the ± 4th order irradiation light are measured respectively. Then, the relative positional deviation amount between the mask A and the wafer B is detected. The obtained signal waveform of the phase difference is the same as that shown in FIGS. 3 (a) and 3 (b) of the previous embodiment, and therefore its details are omitted.

As the type of the diffraction grating used in the present invention, various types such as a reflection type, a transmission type, an amplitude type and a phase type can be used. As for the light source, a horizontal Zeeman laser, a combination of a horizontal Zeeman laser and a 1/4 wavelength plate, a combination of a stabilizing laser and a frequency shifter, and the like are possible. Further, what is shown in the above embodiment is one in which each diffracted light obtained from the mask diffraction grating and the wafer diffraction grating is converted into a beat signal and the phase difference of each beat signal is measured. The displacement of is relative,
Alternatively, it is possible to adopt an absolute position deviation detection method in which a reference beat signal is taken and how much the mask and the wafer are respectively deviated from the reference beat signal.

〔The invention's effect〕

As described above in detail, according to the method and the device of the present invention, while maintaining the required detection resolution of the optical heterodyne position detection system at a high level, the detection range having a reciprocal relationship with this resolution is conspicuously opposite to the conventional one. Therefore, it is possible to detect the minute displacement of the first object and the second object in the quarter micron range, and the detection accuracy can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration according to an embodiment of an alignment apparatus of the fifth invention, FIG. 2 is an explanatory view showing a state of generation of diffracted light at each diffraction grating in this embodiment, and FIG. a) and (b) are diagrams showing signal waveforms of the phase meter obtained as a result of detection of each phase difference in the present embodiment, and FIG. 4 is a schematic diagram showing an embodiment configuration of the alignment apparatus of the fourth invention, and FIG. The figure is a front view showing the irradiation state of the irradiation light seen from the front of the apparatus of the present embodiment, and FIG. 6 is a side view showing the oblique incident state of the irradiation light and the oblique detection state of the diffracted light seen just from the side of the previous figure. FIG. 7 and FIG. 7 are explanatory views of a conventional optical heterodyne position detection method. In the figure, A is a mask, B is a wafer, (1a) is a mask diffraction grating, (1b) is a wafer diffraction grating, (2) is a light source, (30), (31) and (32).
(33) (42) (42a) (43) (43a) (44) (45) are mirrors, (40) (41) (5
2) (53) is the polarization beam splitter, (50) (51) (54) (55) is 1
/ 2 wave plate, (60) (60a) (61) (62) (62a) (63) is a detector, and (7) is a signal processing control circuit.

Claims (5)

[Claims] 1. A first object having a first diffraction grating and a second object having a second diffraction grating are irradiated with coherent light beams having two slightly different frequencies from a vertical direction, or the first and the second objects. By irradiating the second object from the directions of ± nth order, ± n generated respectively from the first and second diffraction gratings.
The next diffracted light is taken out or the diffracted light generated in the vertical direction is taken out from each of these diffraction gratings, and two frequency components are interfered at the time of the diffraction or in the diffracted light path to generate beat signals, respectively. In the position detecting method for detecting the displacement amount of the first and second objects by measuring the phase difference, the absolute value n of the diffraction order is different for the diffracted light extracted from each diffraction grating in the ± nth diffraction direction. This is taken out in a plurality of diffraction directions and further interfered to detect the interference light, or the absolute value n of the order for each irradiation direction from the ± nth order of the coherent light to each diffraction grating.
To each of the diffraction gratings so as to have a plurality of different irradiation directions, and by interfering with the diffracted lights vertically extracted from the first and second diffraction gratings by these irradiations, each beat signal is generated. The phase difference between beat signals finally generated from those having the same absolute value n of the order of ± n-order diffracted light or the result of irradiation of coherent light from the ± n-order directions is extracted in the vertical direction and interferes. Of the diffracted light converted into light, the phase difference between the beat signals finally generated from the interference diffracted light having the same absolute value n of the irradiation direction order is measured, and the first and second phase differences are measured based on the respective phase differences. A position detecting method for detecting a displacement amount of a second object. 2. A first diffraction grating provided on a first object and a second diffraction grating provided on a second object, which are slightly different from each other.
A light source for generating coherent light of a frequency, an incident angle adjusting means for causing the coherent light emitted from the light source to be incident on each of the first and second diffraction gratings from directions of ± nth order, and each diffraction grating At the time when the irradiation light is diffracted, or in the optical path of the diffracted light extracted in the vertical direction from each diffraction grating, the optical interference means for interfering the two frequency components to form the interference light, and the first and second diffraction gratings Detecting means for respectively detecting the beat signals respectively taken out in the vertical direction and generated by the optical interference means, and measuring the phase difference from these beat signals, and based on this phase difference, the first
And a position detecting device having a signal processing means for detecting the displacement amount of the second object, a plurality of different absolute values n of the orders for the irradiation of the coherent light from the ± nth directions to the diffraction gratings by the incident angle adjusting means. The respective diffraction signals can be emitted from the respective directions, and the detection means can also detect each beat signal corresponding to these irradiation directions. Further, the signal processing means can also have ± nth order. Of the diffracted light extracted in the vertical direction as a result of the irradiation of the coherent light from the direction, the phase difference between the beat signals finally generated from the diffracted light having the same absolute value n of the irradiation direction order is measured. A position detecting device, wherein the displacement amount of the first and second objects is detected based on each phase difference. 3. A first diffraction grating provided on a first object and a second diffraction grating provided on a second object, which are slightly different from each other.
A light source for generating coherent light of a frequency and a ± n-order diffracted light out of the diffracted light generated by these diffraction gratings when the coherent light generated by the light source is applied to each of the first and second diffraction gratings. The diffracted light extraction means for performing, the optical interference means for interfering the two frequency components into the interference light in the optical path for extracting the diffracted light, and the beat signal extracted by the diffracted light extraction means and generated by the optical interference means Detection means for detecting each,
In a position detecting device having a signal processing means for measuring the phase difference from these beat signals and detecting the amount of displacement of the first and second objects based on this phase difference, each diffraction grating is obtained by the diffracted light extraction means. Of the diffracted light extracted in the ± n-order diffracted directions from the above, it is extracted in a plurality of diffracted directions in which the absolute values n of the diffracted orders are different, and the detection means also corresponds to these diffracted light extracted directions and each beat signal. And the signal processing means also measures the phase difference between the beat signals finally generated from the diffracted light detected by the detection means having the same absolute value n of the order. Then, the position detecting device is characterized in that the displacement amounts of the first and second objects are detected based on the respective phase differences. 4. A first diffraction grating provided on a first object, a second diffraction grating provided on a second object, a first object and / or
Or slightly different from the moving mechanism that moves the second object 2
A light source for generating coherent light of a frequency, an incident angle adjusting means for causing the coherent light emitted from the light source to be incident on each of the first and second diffraction gratings from directions of ± nth order, and each diffraction grating At the time when the irradiation light is diffracted, or in the optical path of the diffracted light extracted in the vertical direction from each diffraction grating, the optical interference means for interfering the two frequency components to form the interference light, and the first and second diffraction gratings Detecting means for extracting the beat signals respectively generated in the vertical direction and detecting the beat signals generated by the optical interference means, measuring the phase difference from these beat signals, and sending a control signal to the moving mechanism based on this phase difference. In the alignment device having signal processing control means for outputting and aligning by moving the first object and / or the second object, ± n for each diffraction grating by the incident angle adjusting means With respect to the irradiation of coherent light from the next direction, each of these diffraction gratings can be irradiated from a plurality of directions having different absolute values n of the order, and the beat signal of each of the detecting means is also made to correspond to these irradiation directions. Of the diffracted light extracted in the vertical direction as a result of the irradiation of the coherent light from the ± n-order directions, the signal processing control means also determines from the diffracted light having the same absolute value n of the irradiation direction order to the final one. The alignment device is characterized in that the phase difference between the beat signals generated in this way is measured, and a control signal is output to the moving mechanism based on these phase differences. 5. A first diffraction grating provided on a first object, a second diffraction grating provided on a second object, a first object and / or
Or slightly different from the moving mechanism that moves the second object 2
A light source for generating coherent light of a frequency and a ± n-order diffracted light out of the diffracted light generated by these diffraction gratings when the coherent light generated by the light source is applied to each of the first and second diffraction gratings. The diffracted light extraction means for performing, the optical interference means for interfering the two frequency components into the interference light in the optical path for extracting the diffracted light, and the beat signal extracted by the diffracted light extraction means and generated by the optical interference means Detection means for detecting each,
It has a signal processing control means for measuring the phase difference from these beat signals, outputting a control signal to the moving mechanism based on the phase difference, and moving and aligning the first object and / or the second object. In the alignment device, the diffracted light extracting means extracts the diffracted light from the respective diffraction gratings in the ± n-th order diffracting directions in a plurality of diffracting directions having different absolute values n of the diffracted orders, and also in the detecting means. The beat signals can be generated in correspondence with the diffracted light extraction directions, and the signal processing control means also determines from the diffracted light detected by the detection means to the final absolute value n of the same order. The phase difference between the beat signals thus generated is measured, and a control signal is output to the moving mechanism based on each phase difference. Alignment and wherein the.