JPH042116A - Method and device for detecting position and alignment device - Google Patents

Abstract

PURPOSE:To spread the range of detection as detection resolving power required in a position transducer utilizing optical heterodyne interference light is left as it is kept by separating each diffracted light from first and second bodies resulting from the + or - primary irradiation direction and each diffracted light from the first and second bodies resulting from the + or - quaternary irradiation direction respectively and detecting phase difference among beat signals by each diffracted light. CONSTITUTION:Since the planes of polarization are displaced at 900 by half wave plates 50, 51 on their midways in - primary diffracted light and - quaternary diffracted light reflected by mirrors 31, 33, both diffracted light mutually interfere with + primary diffracted light and + quaternary diffracted light respectively by polarizing beam splitters 52, 53, thus acquiring optical heterodyne interference light. The phase difference of beat signals resulting from + or - primary diffracted light and the phase difference of beat signals resulting from + or - quaternary diffracted light are detected in a signal processing control circuit 7, thus measuring the quantities of the relative positional displacement of a mask A and a wafer B within the range of the half pitches of a diffraction grating. The resolving power of + or - quaternary diffracted light is increased by quadruple to that of + or - primary diffracted light.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a position detection method and apparatus using optical heterodyne interference light in semiconductor ultrafine processing, ultraprecision measurement, etc., and a position detection configuration using the same. The present invention relates to an alignment device that performs ultra-precise alignment of two objects.

[Conventional technology]

For precision position detection technology such as synchrotron radiation lithography aligners and photosteppers, for example, JP-A-62
- Like No. 261003, etc.

Optical heterodyne position detection methods are beginning to be put into practical use at the prototype level.

FIG. 7 shows an outline of a position detection means using optical heterodyne interference diffraction light shown in the above-mentioned prior art.
First, the device configuration consists of a mask A, which is the first object.
and a light source consisting of each diffraction grating (la) (lb) formed on the wafer B, which is the second object, and a laser device that generates orthogonal linearly polarized light of two slightly different frequencies.
2) and the direction of the light separated by a polarizing beam splitter (40a) to be described later is adjusted to form the diffraction grating (la) (l
b) incident angle adjustment means consisting of mirrors (42a) (43a) that emit light from the ±n-th direction (n is a positive integer);
42a) (43a) A polarizing beam splitter (40a) and the diffraction grating (la) (lb
) Polarizing plate (56) (57) that interferes each diffracted light taken out in the vertical direction to produce optical heterodyne interference light.
and the polarizing plate (56) (57).
Detectors (60a) (62a) that detect interference diffraction light caused by optical heterodyne interference and generate heat signals.
and the detector (60a) (62
It has a signal processing means (70) that detects the phase shift of the heat signal generated from each of the above and displays it on a phase meter.

The light emitted from the light source (2) has orthogonal linearly polarized two-frequency acid molecules i and f2, and is separated by a polarizing beam splitter (40a) into light with a frequency component of f and light with a frequency component of f2. mirrors (42a) (43
a) for the diffraction grating (la) (lb) ±n
The light is incident from the next direction (for example, the ±1st order direction). Diffraction grating(
la) Light f2, f diffracted in the vertical direction from (lb)
2 (indicated by a broken line in the figure) passes through the mirror (38) and prism mirror (39) and becomes coherent with each polarizing plate (56) (57), and the heat signal is detected by the detector (60a) (62a), respectively. be done. Each detector (60a) (
Between the heat signals detected by the diffraction grating (l
a) A phase difference proportional to the amount of positional deviation (lb) is generated. By detecting this phase difference with the phase meter of the signal processing means (70), the amount of relative positional deviation between the two diffraction gratings (la) (lb) can be known.

[Problem that the invention seeks to solve]

In the above optical heterodyne position detection method, each diffraction grating (
la) Regarding the ±n-order irradiation direction of light with respect to (lb), the smaller the absolute value n of the order, the wider the signal detection range,
The relationship between them is: Signal check range two diffraction gratings (la) (lb) pitch P/2
n, and for example, when n is 1, 17 of the above pitch P
2 is its detection range. However, the exact opposite relationship holds true for the detection resolution, and unless the grating pitch P is made small, the higher the absolute value n of the order, the lower it becomes. Therefore, in order to increase the detection resolution, each diffraction grating (la)
If the irradiation angle of light with respect to (lb) is changed and the absolute value n of the order is increased, the signal detection range will become extremely narrower than the above formula (note that even if the grating pitch P is reduced to increase the detection resolution, Similar results are obtained from the formula).

Therefore, if an attempt is made to obtain higher position detection resolution using such an optical heterodyne position detection method in a synchrotron radiation lithography aligner where the transfer line width is on the order of a sub-half micron, the signal detection range will become extremely narrow. , it was difficult to put it into practical use.

The present invention was devised in view of the above-mentioned problems of the prior art, and provides a position detection method and device capable of expanding the detection range while maintaining the necessary detection resolution, and an alignment device using the position detection configuration. We aim to provide the following.

[Means for solving problems]

Therefore, the position detection method of the present invention uses a mask.

Each of the diffraction gratings provided on a first object such as a wafer and a second object such as a wafer is irradiated with each diffraction grating from a plurality of irradiation directions in which the absolute value n of the order is different for each ±n-order irradiation direction of coherent light. irradiating each with the coherent light, detecting the diffracted light generated in the vertical direction from the first and second diffraction gratings by these irradiations, and interfering the two frequency components at the time of the diffraction or in the middle of the diffraction optical path. Each heat signal is generated based on the optical heterodyne interference diffracted light, and the absolute value n of the order in the irradiation direction of the diffracted light extracted in the vertical direction as a result of irradiation with coherent light from the ±n-order direction is The phase difference between the heat signals finally generated from the same interference diffraction light is measured, and the displacement (in addition to the amount of relative positional deviation) of the first and second objects is calculated based on each phase difference. A reference heat signal is generated to detect the absolute displacement amount (which may be an absolute displacement amount to know the displacement of each of these two objects).

For example, the pitch P of each of the diffraction gratings provided on the first and second objects is set to be large to a certain extent, and a small amount of orthogonal linearly polarized light is applied to each of these diffraction gratings from the upper first-order direction and the ±4th-order direction, respectively. is irradiated with light having two different frequency acid molecules 2, f2, and each diffracted light from the first and second objects originating from the ±1st order irradiation direction and the first and second diffracted light originating from the ±4th order irradiation direction are obtained. Each of the diffracted lights from the object is separated and detected, and the two-frequency components 1 and f2 of these diffracted lights are caused to interfere with each other to generate each heat signal.

Then, by detecting the phase difference between the heat signals caused by the respective diffracted lights from the first and second objects originating from the ±1st order irradiation direction, the signal waveform becomes a linear signal with a period of 172 of the diffraction grating pitch P. Become.

In light of this, if the phase difference between the heat signals due to the respective diffracted lights from the first and second objects derived from the ±4th order irradiation direction is detected, a linear signal with a period of 178 of the above-mentioned diffraction grating pitch P can be detected. Become. In this way, the signal detection range of the latter is 174, but the signal detection resolution is four times that of the former. Therefore, if the two phase differences are determined simultaneously, the displacement position can be measured within the range of 172 of the grating pitch P, and moreover, ±4
This means that the resolution of the diffracted light from the next irradiation direction can be achieved at the same time.

Furthermore, another method for detecting the displacement of the first and second objects is to detect the ±nth-order diffracted light of the diffracted light emitted from the light source and generated from the first and second diffraction gratings, and By interfering the two frequency components to produce optical heterodyne interference diffraction light, heat signals are generated based on this, and the displacement can be detected by measuring the phase difference between these heat signals. , the present invention can also be applied to such a configuration. In this case, ±
The diffracted light taken out in the n-th order diffraction direction is taken out in a plurality of diffraction directions having different absolute values n of the diffraction orders, and further subjected to optical heterodyne interference to detect the interference light. Through this detection, each heat signal is generated, and the phase difference between the finally generated heat signals is measured from those whose absolute values n of the orders of the ±1st-order diffracted lights are the same. Based on each of these phase differences, the first and the displacement position of the second object is detected. Also, the absolute value of the irradiation order and diffraction order is 3.
Needless to say, the light may be irradiated from a plurality of irradiation directions giving three or more different values, or the diffracted light may be extracted from such a plurality of diffraction directions for detection.

In the configuration of the present invention, as for the means for causing light interference, there is a method of using a combination of a polarizing beam splitter and a polarizing plate as described above, but it is also possible to use a combination of a polarizing beam splitter and a 1/2 wavelength plate. It is also possible to use a beam splitter, a half-wave plate, and a polarizing plate in combination. That is, when irradiating coherent light from the ±n-order direction, either only the f1 configuration extracted by the polarizing beam splitter, or the +0-order light having both f□ and f2 components extracted by the beam splitter, or the same polarized beam. One polarization plane of the first n-order light having only the f2 configuration extracted by the splitter or having both f2 and fl components extracted by the beam splitter is shifted by 90 degrees with a 1/2 wavelength plate and irradiated onto each diffraction grating, It is also possible to cause optical heterodyne interference at the time of diffraction (in the latter case, where irradiation interference is made in the form of having both f and f2 components, one of the horizontal or vertical interference light is further filtered through a polarizing plate). ), and if the coherent light is made perpendicularly incident on each diffraction grating and the ±n-order diffracted light is extracted from the diffracted light generated from it, +
The n-th order diffracted light is −1/2 of the n-th order output destination.
It is also possible to perform the same process using a wave plate and cause the ±n-order diffracted light to undergo optical heterodyne interference before the detection point.

Next, the position detection devices of the second and third inventions relate to devices for implementing the position detection method of the first invention, the second invention device has a configuration for extracting diffracted light in the vertical direction, and the third invention device has a configuration for extracting diffracted light in the vertical direction. This is a configuration for extracting light in the ±nth order diffraction direction.

That is, the second invention device includes a first diffraction grating provided on a first object, a second diffraction grating provided on a second object, and a light source that generates coherent light of two slightly different frequencies. an incident angle adjusting means for making the coherent light irradiated from the light source enter each of the first and second diffraction gratings from ±n-order directions; an optical interference means for making optical heterodyne interference light by interfering two frequency components in the optical path of the diffracted lights respectively taken out from the diffraction grating in the vertical direction; detection means for detecting the diffracted light that has become optical heterodyne interference light by the optical interference means and generating heat signals respectively; 2. In a position detection device having a signal processing means for detecting a displacement of an object, the incident angle adjusting means irradiates each diffraction grating with coherent light from ±n-order directions in a plurality of directions in which the absolute value n of the order is different. In addition, the detection means is adapted to correspond to these irradiation directions so as to be able to detect each optical heterodyne interference diffraction light and generate each heat signal. As for the processing means, the phase difference between the heat signals finally generated from the diffracted lights whose absolute values n of the orders in the irradiation direction are equal among the diffracted lights taken out in the vertical direction as a result of the irradiation of coherent light from ±n-order directions. The basic feature is that the displacement positions of the first and second objects are detected based on these phase differences. In addition, in the third invention device, the light is incident in the vertical direction, and the diffracted light is extracted from ±
Since the configuration is such that the diffraction is performed in the n-th order direction, there is no incident angle adjustment means as in the second invention device, and there is no need for a diffraction device such as a mirror or a polarizing beam splitter that takes out the ±n-order diffracted light among the diffracted lights generated from each diffraction grating. It is equipped with a light extraction means, and the light interference means has two
The device is configured to interfere with frequency components. Based on these configurations, the third invention extracts the diffracted light extracted from each diffraction grating in the ±n-order diffraction directions by the diffraction light extraction means in a plurality of diffraction directions in which the absolute value n of the diffraction order differs. At the same time, the detection means is also adapted to detect each optical heterodyne interference diffracted light and to generate each heat signal in correspondence with the direction in which these diffracted lights are taken out, and furthermore, the signal processing means is also arranged to correspond to the direction in which these diffracted lights are extracted. The phase difference between the heat signals finally generated from the diffracted lights having the same absolute value n of the orders is measured, and the displacement position of the first and second objects is detected based on these phase differences. I try to do that.

Furthermore, the alignment devices of the fourth and fifth inventions are based on the position detection devices of the second and third inventions, and further improve the device configuration to a configuration that can align the first object and the second object. This is an improved and improved configuration that includes a moving mechanism for moving the first object and/or the second object, and determines the positions of the first object and the second object from the measured phase difference. A signal processing control means that does not simply include a signal processing means for performing detection, but outputs a control signal to the moving mechanism based on the phase difference, and moves and aligns the first object and/or the second object. The other configurations are the same as those of the second invention and the third invention.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 1 shows the first stage in a synchrotron radiation exposure apparatus.
This figure schematically shows the configuration of an alignment apparatus according to a fifth aspect of the present invention used to align a mask A, which is an object, and a wafer B, which is a second object.

Mask stage (8a) and wafer stage (8b) respectively
is shown and other configurations are omitted.

In this example, a mask diffraction grating (1a) and a wafer diffraction grating (lb) provided on a mask A and a wafer B, and both diffraction gratings (la) are connected via a cylinder lens (20) and a mirror (21). a light source (2) consisting of a transverse Zeeman laser that irradiates laser light (two-frequency coherent light) from a perpendicular direction to (lb); and a movement mechanism showing only the mask stage (8a) and wafer stage (8b). , this irradiation causes both diffraction gratings (la) (lb
) diffracted light extraction means for extracting ±1st-order diffracted light from the diffracted light generated from A 1/2 wavelength plate that shifts the plane of polarization of the diffracted light extracted in the -1st and -4th directions by 90' (
50) The ±1st-order diffracted light and ±4th-order diffracted light taken out by (51) and the mirrors (30) and (32) interfere with each other with the 11th-order diffracted light and the 14th-order diffracted light whose 90' polarization planes are shifted. Furthermore, an optical interference means consisting of polarizing beam splinters (52) (53) to be polarized;
Optical heterodyne interference light of ±1st order and ±4th order diffracted light taken out from the mask diffraction grating (1a) side is reflected by a knife mirror (34) (35) and detected, and the ±1st order resulting from the interference is detected. Heat signal derived from folded light and ±4
a masked first-order light detector (60) and a masked fourth-order light detector (61) that generate a heat signal derived from the next-order diffracted light;
Furthermore, ± is taken out from the wafer diffraction grating (1b) side.
a wafer primary optical detector (62) that detects optical heterodyne interference light of the first-order and ±4th-order diffracted lights, and generates a heat signal derived from the ±1st-order diffracted light and a heat signal derived from the ±4th-order diffracted light generated from the interference light; Wafer 4th order optical detector (6
3), and the heat signals generated by each of these detection means are input, and the phase difference between the heat signals originating from the ±1st-order diffracted light and the phase difference between the heat signals originating from the ±4th-order diffracted light are detected. a signal processing control circuit (7) that measures the phase difference and outputs a control signal to the moving mechanism based on these phase differences;
It has

In the above device configuration, the mask diffraction grating (1a) and the wafer diffraction grating (lb) are slightly shifted in the longitudinal direction of the grating. Further, a light transmission window (1c) is provided on the mask A surface, and irradiation of the coherent light onto the wafer diffraction grating (1b) and extraction of the diffracted light from the diffraction grating (1b) are performed through this light transmission window (1c). 1c).

Furthermore, a phase meter (not shown) for displaying each measured phase difference is also installed in the signal processing control circuit (7).

How to use the above device configuration will be explained next.

The transverse Zeeman laser of the light source (2) has orthogonal linear polarization 2
Light containing frequency components 1 and f2 is generated, and this coherent light is irradiated vertically onto a mask diffraction grating (1a) and a wafer diffraction grating (1b), respectively. At this time, the wafer diffraction grating (1b) is irradiated through the light transmission window (1c).

Due to this irradiation, diffraction light is generated in both the diffraction gratings (la) and (lb) in each direction as shown in Figure 2, of which ±1
The second order diffracted light is sent to the mirrors (30) (31), and the ±4th order diffraction light is sent to the polarizing beam splitter (32) (33).
52) It is reflected in the (53) direction, and from there, a part of it is reflected to the mask primary light detector (60) and the mask 4th order light detector (61) via the knife mirrors (34) and (35), and the rest is is the wafer primary optical detector (62
) and the wafer fourth-order optical detector (63), where it is detected. Among the above diffracted lights, mirrors (31) (33
The 11th-order diffracted light and the 14th-order diffracted light reflected by Therefore, the +1st-order diffracted light and the ±4th-order diffracted light interfere with each other at the polarizing beam splitters (52) and (53), respectively, to form optical heterodyne interference light. Therefore, each detector (60) (61) (62) (6
In 3), heat signals are generated by the interference light, and these heat signals are sent to the signal processing control circuit (7). In the circuit (7), the heat signal sent from the mask primary optical detector (60) and the wafer primary optical detector (60) are processed.
2) The phase difference of the heat signal sent from the
A signal waveform as shown in FIG. 3(a) is obtained. Similarly, this signal processing control circuit (7) measures the phase difference between the heat signal sent from the mask 4th light detector (61) and the heat signal sent from the wafer 4th light detector (63). A signal waveform as shown in FIG. 4(b) is obtained. The signal waveform shown in FIG. 3(a) is a linear signal with a period of 1/2 pitch of the diffraction grating, and the signal waveform shown in FIG. 3(b) is a linear signal with a period of 178 pitches of the diffraction grating.

In this way, the signal processing control circuit (7) detects the phase difference between the heat signals derived from the ±1st-order diffracted light and the phase difference between the heat signals derived from the ±4th-order diffracted light, so the 1/2 pitch of the diffraction grating is The amount of relative positional deviation between mask A and wafer B can be measured within this range.

Moreover, the resolution of ±4th order diffracted light [phase meter resolution is 1°]
In terms of degree, the resolution is (P/8)/360", which is four times the resolution of the ±1st-order diffracted light.]
can be achieved at the same time.

FIG. 4 shows the construction of an embodiment of the alignment apparatus of the fourth invention, which is also used for alignment of mask A and wafer B in a synchrotron radiation exposure apparatus.

In the device configuration of this embodiment, a transverse Zeeman laser light source (2)
A part of the coherent light having f2 is sent to the polarizing beam splitter (40) side by the half mirror (22), and the rest is sent to the mirror (22).
3) and enters another polarizing beam splitter (41) side, and the coherent light is separated into light having an f1 configuration and an f2 configuration by both polarizing beam splitters (40) and (41), respectively, and is further separated by a mirror ( 42) (43) and mirrors (44) (45) in the +1st order direction and ±4 with respect to the mask diffraction grating (1a) and the wafer diffraction grating (1b), respectively.
Irradiate from the following direction.

At this time, as shown in Fig. 5, the polarization plane of the light of f0 configuration is shifted by 90'' by the 1/2 wavelength plate (50) (51), and each diffraction grating (l) is shifted by the mirror (42) (44).
a) (lb) is irradiated from the +1st direction and +4th direction. Furthermore, in this example, the diffracted light generated by irradiation from the +1st-order direction and the diffracted light generated by irradiation from the ±4th-order direction are both generated in the vertical direction and overlap, so when viewed from exactly the side in FIG. As shown in Fig. 6, which shows the state in which the diffracted light is extracted, the extraction of the diffracted light corresponds to the angle of oblique incidence by making the irradiation in the +1st-order direction and the irradiation in the ±4th-order direction obliquely incident at different angles. It is designed so that it can be performed in any direction (oblique detection is possible).

The light irradiated in the above manner is transmitted to each diffraction grating (la) (
When diffracted by the mirror (36) (37) and the Naifezi mirror (3), it becomes an optical heterodyne interference light.
4) Mask primary light detector (60) via (35)
), a wafer primary optical detector (62), a mask 4th optical detector (61), and a wafer 4th optical detector (63).
) are detected as heat signals.

Furthermore, each detected heat signal is sent to a signal processing control circuit (7).
The phase difference of the heat signal derived from the ±1st irradiation light and the phase difference of the heat signal derived from the ±4th irradiation light are measured, respectively, and the amount of relative positional deviation between the mask A and the wafer 8 is calculated. Detect each. The signal waveform of the obtained phase difference is the same as that shown in FIGS. 3(a) and 3(b) of the previous embodiment, and therefore its details will be omitted.

It should be noted that various types of diffraction gratings can be used in the present invention, including reflection type, transmission type, amplitude type, and phase type. As for the light source, in addition to a transverse Zeeman laser, a combination of an axial Zeeman laser and a 174 wavelength plate, a combination of a stabilized laser and a frequency sick, etc. are possible. Furthermore, in the example described above, each diffracted light obtained from a mask diffraction grating and a wafer diffraction grating is converted into a heat signal, and the phase difference of each heat signal is measured. Although the displacement of is relative,
Alternatively, it is also possible to adopt an absolute positional deviation detection method in which a reference heat signal is taken and the extent to which the mask and wafer are respectively deviated from the reference heat signal is measured.

〔Effect of the invention〕

As detailed above, according to the method and device of the present invention, while maintaining the high detection resolution required by the optical heterodyne position detection method, the detection range, which has a contradictory relationship with this resolution, can be changed contrary to the conventional method. This makes it possible to detect minute displacements in the sub-half micron range between the first object and the second object, and this detection also makes it possible to dramatically improve alignment accuracy. .

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of an embodiment of the alignment device of the fifth invention, FIG. 2 is an explanatory diagram showing the generation situation of diffracted light at each diffraction grating in this embodiment, a) (b)
) is a diagram showing the signal waveform of the phase meter obtained as a result of detection of each phase difference in this embodiment, FIG. 4 is a schematic diagram showing the configuration of an embodiment of the alignment device of the fourth invention, and FIG. Fig. 6 is a front view showing the irradiation situation of the irradiation light seen from the front of the device in the example, Fig. 6 is a side view showing the oblique incidence situation of the irradiation light and the oblique detection situation of the diffracted light as seen from the previous side, and Fig. 7 is an explanatory diagram 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, and (3) is a mask grating.
0) (31) (32) (33) (42) (4
2a) (43) (43a) (44) (45) are mirrors, (40) (41) (52) (53) are polarizing beam splitters, (50) (51) (54)'(
55) is a 172 wavelength plate, (60) (60a) (61
) (62) (62a) (63) is a detector, (
7) shows each signal processing control circuit. 1a...Mask diffraction grating 1b...Wafer diffraction grating 1C...Light transmission window Figure 2 Procedure amendment (voluntary) Amendment contents January 76, 1990

Claims (5)

[Claims] (1) Coherent light of two slightly different frequencies is irradiated vertically onto a first object having a first diffraction grating and a second object having a second diffraction grating, or detecting the ±nth order diffracted light generated from the first and second diffraction gratings respectively by irradiating the object from the ±nth order directions, or detecting the diffracted light generated in the vertical direction from each of these diffraction gratings, and By interfering the two frequency components at the time of the diffraction or in the middle of the diffracted optical path to produce an optical heterodyne interference diffracted light, heat signals are respectively generated based on this,
By measuring the phase difference between these heat signals, the first
In the position detection method for detecting the displacement of a second object, the diffracted light extracted from each diffraction grating in the ±nth order diffraction direction is extracted in a plurality of diffraction directions in which the absolute value n of the diffraction order is different. Furthermore, optical heterodyne interference is caused to detect this interference light, or these diffraction gratings are irradiated with a plurality of irradiation directions in which the absolute value n of the order is different for each irradiation direction from the ±nth order of the coherent light to each diffraction grating. These irradiations cause the first and second
The diffracted lights taken out in the vertical direction from the diffraction gratings and further converted into optical heterodyne interference lights are detected, and each heat signal is generated by the detection of the diffracted lights, so that the absolute values n of the orders of the ±n-th diffracted lights are equal. The phase difference between the heat signals finally generated from the object or the absolute order of the order in the irradiation direction of the diffracted light extracted in the vertical direction and made into optical heterodyne interference light as a result of irradiation with coherent light from the ±n-order direction A position detection method that measures phase differences between heat signals finally generated from interference diffraction lights having the same value n, and detects displacement positions of the first and second objects based on these phase differences. (2) A first diffraction grating provided on a first object, a second diffraction grating provided on a second object, a light source that generates coherent light of two slightly different frequencies; an incident angle adjusting means for making the coherent light incident on each of the first and second diffraction gratings from ±n-order directions; an optical interference means that interferes two frequency components in the optical path of the diffracted lights taken out respectively to produce optical heterodyne interference light; detection means for detecting the diffracted light that has become the optical heterodyne interference light and generating heat signals respectively;
In a position detection device having a signal processing means for detecting a displacement of an object, the incident angle adjusting means irradiates each diffraction grating with coherent light from ±n-order directions from a plurality of directions with different absolute values n of the orders. In addition to making it possible to irradiate each of these diffraction gratings, the detection means is also made to correspond to these irradiation directions so that each optical heterodyne interference diffraction light can be detected and each heat signal can be generated, and furthermore, the above-mentioned signal processing As for the means, the phase difference between the heat signals finally generated from the diffracted lights having the same absolute value n of the orders in the irradiation direction among the diffracted lights taken out in the vertical direction as a result of the irradiation of coherent light from ±n-order directions is determined. A position detection device characterized in that the positions of the first and second objects are detected based on the phase differences of the first and second objects. (3) a first diffraction grating provided on a first object, a second diffraction grating provided on a second object, a light source that generates coherent light of two slightly different frequencies, and a light source that generates coherent light of two slightly different frequencies; a diffracted light extracting means for extracting ±n-order diffracted light among diffracted lights generated from the first and second diffraction gratings when coherent light is irradiated onto each of the first and second diffraction gratings; an optical interference means for interfering two frequency components to produce optical heterodyne interference light;
Detection means for detecting ±n-order diffracted light extracted by the diffracted light extraction means and turned into optical heterodyne interference light by the optical interference means to generate heat signals, respectively;
In a position detection device having a signal processing means for measuring a phase difference from these heat signals and detecting displacement of the first and second objects based on this phase difference, each diffraction grating is detected by the diffraction light extraction means. Regarding the diffracted light extracted in the ±nth order diffraction direction from The interference diffracted light can be detected and each heat signal can be generated, and the signal processing means is finally generated from the diffracted lights having the same order absolute value n among the diffracted lights detected by the detection means. A position detection device characterized in that a phase difference between heat signals is measured, and displacement positions of the first and second objects are detected based on these phase differences. (4) A first diffraction grating provided on the first object, a second diffraction grating provided on the second object, and a movement mechanism that moves the first object and/or the second object, a light source that generates coherent light of two different frequencies; an incident angle adjusting means that causes the coherent light irradiated from the light source to be incident on each of the first and second diffraction gratings from ±n-order directions; an optical interference means for generating optical heterodyne interference light by interfering two frequency components at the time when the irradiated light is diffracted by the diffraction grating or during the optical path of the diffracted light taken out in the vertical direction from each diffraction grating; detection means for generating heat signals by detecting the diffracted lights taken out in the vertical direction from the diffraction gratings and turned into optical heterodyne interference lights by the optical interference means; and measuring the phase difference from these heat signals. and outputs a control signal to the moving mechanism based on this phase difference to move and align the first object and/or the second object. irradiation of each diffraction grating with coherent light from ±n-order directions by irradiating each diffraction grating from a plurality of directions with different absolute values n of orders, and also for the detection means to irradiate these irradiation directions. Detection of each optical heterodyne interference diffraction light and generation of each heat signal can be performed in accordance with the above-mentioned signal processing control means. The phase difference between the heat signals finally generated from the diffracted lights having the same absolute value n of the order in the irradiation direction is measured, and a control signal is output to the moving mechanism based on each of these phase differences. An alignment device characterized by: (5) A first diffraction grating provided on the first object, a second diffraction grating provided on the second object, and a movement mechanism that moves the first object and/or the second object, A light source that generates coherent light of two different frequencies, and ±n-order diffracted light of the diffracted light generated from these diffraction gratings when the coherent light generated from the light source is irradiated to each of the first and second diffraction gratings. a diffracted light extracting means for extracting the diffracted light; an optical interference means for interfering two frequency components in the middle of the extracting optical path of the diffracted light to produce optical heterodyne interference light;
Detection means for detecting ±n-order diffracted light extracted by the diffracted light extraction means and turned into optical heterodyne interference light by the optical interference means to generate heat signals, respectively;
It has a signal processing control means that measures the phase difference from these heat signals, outputs a control signal to the moving mechanism based on this phase difference, and moves and aligns the first object and/or the second object. In the alignment device, the diffraction light extraction means extracts the diffracted light extracted from each diffraction grating in the ±n-order diffraction direction in a plurality of diffraction directions in which the absolute value n of the diffraction order is different, and the detection means It is possible to detect each optical heterodyne interference diffracted light and generate each heat signal in correspondence with the direction in which these diffracted lights are taken out, and furthermore, the signal processing control means is configured to detect the order of each diffracted light detected by the detection means. A phase difference between heat signals finally generated from heat signals having the same absolute value n is measured, and a control signal is output to the moving mechanism based on each of these phase differences. Alignment device.