JPH0465604A - Method and device for position detection and aligning device - Google Patents

Abstract

PURPOSE:To detect the quantities of displacement of a 1st and a 2nd body by measuring the phase difference between beat signals obtained with diffracted light beams from diffraction gratings which are provided to the 1st and 2nd bodies and have equal grating constants. CONSTITUTION:A signal processing control circuit 7 measures the phase difference between the beat signal sent from a mask P1 detector 60 and the beat signal from a wafer P1 detector 62. The circuit 7 also measures the phase difference between the beat signal sent from a mask P2 detector 61 and the beat signal sent from a wafer P2 detector 63. Then the circuit 7 detects the phase difference between the beat signals from diffraction gratings 10 which has the pitch of masks A and B, i.e. 8mum in this case and the phase difference between the beat signals from diffraction gratings 11 which have the same pitch, i.e. 1.5mum in this case, so the quantity of the relative position shift between the wafers A and B can be measured within a range of 4mum and the quantity of displacement between the bodies A and B is obtained.

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
Optical heterodyne position detection methods are beginning to be put into practical use at the prototype level, as in Patent No. 261003 and Japanese Patent Application Laid-Open No. 64-89323.

FIG. 6 shows an outline of a position detecting means using optical heterodyne interference diffraction light shown in the former of the above-mentioned conventional techniques. Each diffraction grating (xa) (lb) formed on the wafer B, which is a second object, and a light source (2) consisting of a laser device that generates orthogonal linearly polarized light of two slightly different frequencies; Polarizing beam splitter (
The direction of the separated light is adjusted by the diffraction grating (52a).
la) incident angle adjustment means consisting of mirrors (40a) and (41a) that emit light from the direction (n is a positive integer) toward (lb), and the mirror that separates the two polarized lights coming from the light source (2) (40a) A polarizing beam splitter (52a) that branches in the (41a) direction, and the diffraction grating (
la) A polarizing plate (5
4) An optical interference means consisting of (55) and this polarizing plate (5)
4) A detector (60
a) A detection means (62a), and a signal processing means (70) for detecting a phase shift of the beat signal generated from each of the detectors (60a) and (62a) and displaying the detected phase shift on a phase meter. There is.

The light emitted from the light source (2) has orthogonal linearly polarized two-frequency acid molecules 1 and f2, and is separated by the polarizing beam splitter (52a) into light with a frequency component of fl and light with a frequency component of f2. , mirrors (40a) (41
±n for the diffraction grating (la)'(lb) by a)
The light is incident from the next direction (for example, the ±1st order direction). Diffraction grating(
la) Light f1, f diffracted in the vertical direction from (lb)
, (indicated by broken lines in the figure) pass through the mirror (44a) and prism mirror (44b) to each polarizing plate (54) (55).
They become coherent, and beat signals are detected by the detectors (60a) and (62a), respectively. Each detector (60a) (
Between the beat signals detected by the diffraction grating (l
a) A phase difference proportional to the amount of positional deviation (lb) is generated. By detecting which phase difference is detected by 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.

In addition, in the latter position detection means, the structure of the above-mentioned incident angle adjustment means is simply replaced with a means composed of a reference grating and a Fourier transform optical system.

The basic configuration is the same as the former configuration.

[Problems to be solved by the invention] In the optical heterodyne position detection method described above, each diffraction grating (
la) The larger the number of grating chambers in (1b), that is, the grating pitch P, the wider the signal detection range, and the relationship between them is: Signal detection range = Diffraction grating (la) (lb) pitch P/
2n However, n: the absolute value of the order in the irradiation direction of coherent light, for example, when n is 1, 1/2 of the above pitch P
is the detection range. However, the exact opposite relationship holds true for detection resolution.

Assuming that the accuracy of the phase meter resolution is approximately 1°, the detection resolution is:

Detection resolution=signal detection box H/360', and unless the absolute value n of the order in the irradiation direction of the light is increased, the accuracy of the detection resolution decreases as the grating pitch P increases. Therefore, in an attempt to increase the detection resolution, a small diffraction grating (Ia) ('l) with the grating pitch P is
If you try to use b), the signal detection range will be much narrower than the above formula (note).

Even when the detection resolution is increased by increasing the absolute value n of the order in the irradiation direction of the coherent light, similar results are obtained according to the above equation).

Therefore, if an attempt is made to obtain higher position detection resolution by 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 quarter 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, in the position detection method of the present invention, with respect to the diffraction gratings provided on the first and second objects such as masks and wafers,
Two or more types of diffraction gratings with different grating constants are arranged side by side, and each of these diffraction gratings is perpendicular to each other (the absolute value n of the order is the same but the grating pitch P is different, so in reality, it is on the + side and - Coherent light of two slightly different frequencies is irradiated from each side (in multiple directions), and the diffracted light generated in the vertical direction from each diffraction grating is detected by this irradiation, and at the time of this diffraction or in the diffracted light optical path. Beat signals are generated based on these by interfering two frequency components on the way to form optical heterodyne interference diffracted light, and among the above-mentioned diffraction gratings provided on the first and second objects, those having the same grating constant The phase differences between the beat signals obtained from the diffracted lights are measured, and the first
and the displacement amount of the second object (in addition to the relative positional displacement amount, it may also be an absolute positional displacement amount that generates a reference beat signal to know the displacement amount of each of these two objects).

For example, two diffraction gratings with a grating pitch P and a grating pitch P2 where Px>p2 (however, P
, = m) are arranged in two rows on each of the first and second objects (a group of diffraction gratings with a grating pitch P2 may be arranged next to a group of diffraction gratings with a grating pitch P□). ), and by irradiating these diffraction gratings with light having two slightly different frequency acid molecules 1 and f2 of orthogonal linearly polarized light from the ±1st order direction, the grating pitch P, The diffracted light from the diffraction grating consisting of P2 and the diffracted light from the diffraction grating having a grating pitch P2 are each separated and detected, and the two-frequency acid molecules f2 of these diffracted lights are made to interfere with each other to generate each beat signal. .

Then, if the phase difference between the beat signals due to the diffracted light from each diffraction grating of the grating pitch P1 in the first and second objects is detected, the signal waveform will be 172
It becomes a linear signal with a period of . Moreover, if the phase difference between the beat signals due to the diffracted light from each diffraction grating with the grating pitch P2 is detected, the signal waveform will be 172 times the grating pitch P2.
It becomes a linear signal with a period of . Therefore, if the former signal waveform is adopted, a detection range m times that of the latter can be covered, and if the latter signal waveform is adopted, a detection resolution m times that of the former can be obtained. Therefore, by simultaneously detecting the phase difference of both signals, it is possible to cover the detection range of the diffraction grating with the grating pitch P while maintaining the resolution of the diffraction grating with the grating pitch P2.

Furthermore, another method for detecting the amount of displacement of the first and second objects is to detect the ±nth-order diffracted light among the diffracted lights emitted from the light source in the vertical direction and generated from the respective diffraction gratings of the first and second objects. By detecting the diffracted light and interfering the two frequency components in the middle of the optical path to create an optical heterodyne interference diffracted light, beat signals are generated respectively based on this, and by measuring the phase difference of these beat signals, the amount of displacement is determined. It is also possible to detect
The present invention can also be applied to such a configuration. In this case as well, two or more diffraction gratings with different grating constants are arranged side by side and placed on each of the first and second objects, and the absolute values n of the orders in the power direction of the ±nn order from these diffraction gratings are the same. Since the lattice pitch P is different, in reality, +
The diffracted lights extracted in a plurality of directions (on the side and on the negative side) are subjected to optical heterodyne interference, and the interference light is detected. Each beat signal is generated by the detection, and the phase difference between the beat signals obtained from the diffracted light of the diffraction gratings having the same grating constant among the diffraction gratings provided on the first and second objects is measured, respectively. The displacement amounts of the first and second objects are detected based on each phase difference. However, in the above configuration, if the grating pitch of the diffraction grating provided on each of the first and second objects is P,,P, then P
If it is an integral multiple of 2, the ±Q-order diffraction light originating from the diffraction grating at pitch P1 and the ±1st-order diffraction light originating from the pitch P2 diffraction grating may be emitted in the same direction, resulting in noise.
It is desirable to use a non-integer multiple.

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 172 wavelength plate. Alternatively, it is also possible to use a beam splitter, a half-wave plate, and a polarizing plate in combination. In other words, when irradiating coherent light from the ±n-order direction, only the f□ acid component extracted by the polarizing beam splitter or the +0-order light having both the f and f2 components extracted by the beam splitter. Similarly, one polarization plane of the first n-order light having only the f2 configuration extracted by the polarizing beam splitter or having both f2 and fi components extracted by the beam splitter is polarized at 90' with a 172 wavelength plate.
It is also possible to irradiate each diffraction grating at different intervals and cause optical heterodyne interference at the time of diffraction (in the latter case, where irradiation interference is performed in a form that has both f and f2 components,
(One of the horizontal or vertical interference lights is further cut by a polarizing plate, and the remaining interference light is detected.) Then, the coherent light is vertically incident on each diffraction grating, and the diffracted light generated therefrom is detected. When the ±nth order diffracted light is taken out, the +nth order diffracted light is the -nth order diffracted light, and one of them is 17
It is also possible to perform the same process using a two-wavelength plate and cause the ±n-order diffracted light to undergo optical heterodyne interference before the point of detection.

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 ±nn next power direction.

That is, the second invention device includes a diffraction grating made of two or more different grating constants arranged side by side on each of the first and second objects, and a light source that generates coherent light of two strongly different frequencies. , coherent light emitted from the light source is applied to each diffraction grating of the first and second objects, respectively.
Optical heterodyne is achieved by using an incident angle adjusting means for making the light incident from the n-th direction, and interfering two frequency components at the time when the irradiated light is diffracted by each diffraction grating or in the middle of the optical path of the diffracted light taken out from each diffraction grating in the vertical direction. A beat signal is generated by detecting the diffracted light taken out in the vertical direction from each of the diffraction gratings of the first and second objects and turned into optical heterodyne interference light by the optical interference means. These phase differences are determined by measuring the phase difference between the beat signals obtained by the detection means respectively generated by the detection means and the beat signals obtained by the detection means from the diffracted lights of the diffraction gratings of the first and second objects having the same grating constant. and signal processing means for detecting the displacement amounts of the first and second objects based on. In addition, in the third device of the present invention, since the light is incident in the vertical direction and the diffracted light is taken out in the ±nn order output direction, there is no incident angle adjustment means as in the second device of the invention, and there is no angle of incidence adjustment means as in the second device of the present invention. It is equipped with a diffracted light extracting means such as a mirror or a polarizing beam splitter for extracting ±n-order diffracted light out of the generated one-fold diffracted light, and as for the optical interference means, it is a device that performs interference of two frequency components in the middle of the extracting optical path of the diffracted light. It is structured as follows. With these configurations as a prerequisite configuration, the third invention extracts the ±nn order diffracted light in the output direction from each diffraction grating by the diffraction light extraction means, and also extracts each optical heterodyne with respect to the detection means corresponding to these diffraction light extraction directions. The interference diffraction light can be detected and each beat signal can be generated, and the signal processing means is provided on each of the first and second objects among the respective diffraction lights detected by the detection means. Measure the phase difference of the beat signals obtained from the diffracted light between diffraction gratings with the same grating constant,
The amount of displacement of the first and second objects is detected based on these phase differences.

Furthermore, the alignment devices of the fourth and fifth inventions are based on the position detection devices of the second and third inventions, and the device configuration is further changed to a configuration that can align the first object and the second object. It has been developed and improved, and its unique structure is the first one.
It does not simply include a moving mechanism that moves the object and/or the second object, and a signal processing means that detects the positions of the first object and the second object from the measured phase difference. The apparatus includes a signal processing control means for outputting a control signal to the moving mechanism based on the phase difference to move and align the first object and/or the second object, and the other configurations are according to the second invention and the third invention. The structure is the same as that of the 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 diagram schematically shows the configuration of an alignment device according to the fifth invention used for aligning a mask A, which is an object, and a wafer B, which is a second object, and the configuration of each moving mechanism for the mask and wafer is omitted in the figure. has been done.

In this example, the second
As shown in the figure, a diffraction grating with a grating pitch of 8 μm (
10) and a diffraction grating with a grating pitch of 1.5 μm on the lower side (
11) are arranged side by side.

In addition to the above configuration, in this example, cylinderless (20)
and each of the above-mentioned diffraction gratings (10) (
Light g (2) consisting of a transverse Zeeman laser that irradiates two-frequency coherent light from the perpendicular direction to 11), a moving mechanism (not shown) constituted by a mask stage and a wafer stage, and each diffraction grating by the above irradiation. (1
0) Among the diffracted lights generated from (11), the mirrors (30) and (31) take out the ±1st-order diffracted light generated from the diffraction grating (10) with a pitch of 8 μm, and the ± generated from the diffraction grating (11) with a pitch of 1.5 μm. Mirror (3
2) The diffracted light extraction means (33) and the mirror (3)
1) The 1st-order diffracted light taken out by the 172-wave plate (50) (51) and the mirrors (30) (32) that shift the polarization plane of the diffracted light taken out in the +1st-order direction by (33) by 90 degrees is an optical interference means consisting of polarizing beam splinters (52) and (53) that interfere with the ±1st-order diffracted light whose polarization plane has been shifted by 90°, and further polarize the light therein;
Optical heterodyne interference light of ±1st-order diffracted light extracted from each diffraction grating (10) (11) on the mask A side is detected, and a diffraction grating (10
)-derived beat signal and a diffraction grating with a pitch of 1.5 μm (
11) Optical heterodyne of the ±1st-order diffracted light extracted from the mask P editor (60) and mask P2 detector (61) that generate the original beat signal, and also from each diffraction grating (10) (11) on the wafer B side. The interference light is reflected by a knife mirror (34) (35) and detected.
Diffraction grating (10) with a pitch of 8 μm generated from the interference light
The original beat signal and the diffraction grating with a pitch of 1.5 μm (11
wafer P editor (
62) and a wafer P2 detector (63), and the beat signals generated by each of these detection means are input, and the detection means derived from the diffracted light from the diffraction grating (10) with a pitch of 8 μm on the mask A and wafer B is detected. The phase difference between the beat signals derived from the diffracted light from the diffraction grating (11) with a pitch of 1.5 μm on the mask A and the wafer B is determined as well as the phase difference between the beat signals, and based on these phase differences, and a signal processing control circuit (7) that outputs a control signal to the moving mechanism.

In addition, in the above device configuration, the diffraction grating (10
)(11), the diffraction grating (10)(11) of wafer B
) is slightly shifted in the longitudinal direction of the grid. Also, mask A
A light transmission window (lc) is provided on the surface, and irradiation of the coherent light to each diffraction grating (10) (11) of the wafer B and extraction of the diffracted light from the diffraction grating (10) (11) are performed. This is done through this light transmission window (lc). 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
It generates light containing a frequency component, f2, and directs this coherent light through the diffraction gratings (10) (1) of mask A in the vertical direction.
1) and the diffraction gratings (10) and (11) of wafer B, respectively. At this time, the diffraction grating (to) (11) of wafer B
The light will be irradiated through the light transmission window (lc). By this irradiation, each diffraction grating (10) (11
), diffracted light is generated in each direction as shown in Figure 1, and among them, the diffraction grating (
The ±1st-order diffracted light emitted from the mirror (3o) (
In 31), the pitch of mask A and wafer B is 1.
The ±1st-order diffracted light emitted from the 5 μm diffraction grating (11) is reflected by the mirrors (32) (33) toward the polarization beam splitter (52) (53), and a part of it is then sent to the mask P editor (60). and the mask P2 detector (61), and the rest is the knife mirror (34).
) (35) to the wafer P editor (62) and wafer P2 detector (63), where it is detected.

Of the above diffracted light, it is reflected by the mirrors (31) (33) and the grating pitch of mask A and wafer B is 8μ.
The +1st-order diffracted light emitted from each diffraction grating (to) (11) of m and 1.5 μm passes through a 1/2 wavelength plate (50
) (51), the plane of polarization is shifted by 90° (the vertical component is shifted horizontally, and the horizontal component is shifted vertically), so the polarization beam splitter (52) (53) Each diffraction grating (lo) (tf
) and interferes with the 1st-order diffracted light extracted from the 1st-order diffraction light, resulting in optical heterodyne interference light. For this reason, each detector (60)
(61) (62) In (63), beat signals are generated by the interference light, and these beat signals are sent to the signal processing control circuit (7). In the circuit (7), the mask P□
The phase difference between the beat signal sent from the detector (60) and the beat signal sent from the wafer P□ detector (62) is measured, and a signal waveform as shown in FIG. 3(a) is obtained. It turns out. Similarly, this signal processing control circuit (7) receives the beat signal sent from the mask P2 detector (61) and the wafer P2 detector (63).
) is measured, and a signal waveform as shown in FIG. 3(b) is obtained. The signal waveform shown in FIG. 3(a) is a linear signal with a period of 4 μm, and the signal waveform shown in FIG. 3(b) is a linear signal with a period of 0.75 μm. In this way, the signal processing control circuit (7) calculates the phase difference between the beat signals derived from the diffraction grating (10) with a pitch of 8 μm on mask A and wafer B, and the beat signal derived from the diffraction grating (11) with the same pitch of 1.5 μm. Since the phase difference of the signal is detected, the relative positional deviation between mask A and wafer B can be measured within a range of 4 μm, and the resolution of the diffraction grating (11) with a pitch of 1.5 μm (phase meter resolution) If the angle is about 1°, the resolution is 0.75 μm.
/360', which is approximately 5.3 times the resolution of the diffraction grating (10) with a grating pitch of 8 μm.

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 configuration of this embodiment as well, each diffraction grating (10) (11
) are arranged side by side, and coherent light having two frequency components □ and f2 emitted from the transverse Zeeman laser light source (2) is transmitted through a cylinder lens (20) and a part of it by a half mirror (22). enters the polarizing beam splitter (53), and the rest enters another polarizing beam splitter (52) via the mirror (23), and the coherent light is transmitted by the plane polarizing beam splitters (52) and (53), respectively. The light is separated into light having an f1 component and an f2 configuration, and is further split into mirrors (40) (41) and mirrors (42), respectively.
) According to (43), the diffraction grating (
1'0) and (11) are irradiated from the upper primary direction. At this time, as shown in Figure 4, the light of the f1 component is 1/2
The polarization plane is shifted by 90° by the wave plates (50) and (51), and each diffraction grating (1
0) (11) is irradiated from the +1st order direction. Furthermore, in this example, the diffracted light generated by irradiating the diffraction grating (10) with a grating pitch of 8 μl and the diffracted light generated by irradiating the diffraction grating (11) with a grating pitch of 1.5 μl are both generated in the vertical direction. Therefore, as shown in Figure 5, which shows the state seen from the side of Figure 4, the irradiation to the diffraction grating (10) with a pitch of 8 μm and the pitch of 1.5 μm are shown.
By making the irradiation onto the diffraction grating (11) obliquely incident at different angles, the diffracted light can be extracted in a direction corresponding to the oblique incident angle (oblique detection can be performed).

The light irradiated in the above manner is applied to each diffraction grating (10).
(11), it becomes an optical heterodyne interference light and mirrors (44)'(45) and Naifezi mirror (
46) Mask P1 detector (60
) and are detected as beat signals by the wafer P editor (62), mask P2 detector (61), and wafer P2 detector (63), respectively.

Furthermore, each detected beat signal is sent to a signal processing control circuit (7).
The phase difference between the beat signals input from the diffraction grating (10) with a grating pitch of 8 μm provided on each of mask A and wafer B and the beat signal originating from the diffraction grating (11) with a grating pitch of 1.5 μm The relative positional deviation between the mask A and the wafer 8 is detected by measuring the phase difference between the signals. The signal waveform of the obtained phase difference is the same as the third one in the previous example.
It is the same as that shown in Figures (a) and (b), so its details will be omitted.

Note that various types of diffraction gratings can be used in the present invention, such as reflection type, transmission type, amplitude type, phase type, and blazed 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 shifter, etc. are possible. Furthermore, in the embodiment shown above, each diffracted light obtained from a mask diffraction grating and a wafer diffraction grating is converted into a beat signal and the phase difference of each beat signal is measured.
Although the amount of displacement between the mask and wafer obtained by this is relative, an absolute positional deviation detection method uses a separate reference beat signal and measures how much the mask and wafer are deviated from each other. can also be adopted.

〔Effect of the invention〕

As detailed above, according to the method and device of the present invention, while maintaining the high inspection resolution required by the optical heterodyne position detection method, the detection range, which has a contradictory relationship with this resolution, can be significantly increased. Therefore, it becomes possible to detect minute displacements in the quarter micron range between the first object and the second object, and the alignment accuracy can be dramatically improved by this detection.

[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 side view showing the oblique incidence of irradiation light and the oblique detection state of diffracted light as viewed from the side, and is an explanatory diagram of the conventional optical heterodyne position detection method. In the figure, A is a mask, B is a wafer, (la) (lb) (
1o) (11) is a diffraction grating, (2) is a light source, (30)
(31) (32) (33) (40) (40a) (
41) (41a) (42) (43) are mirrors (52
) (52a) (53) is a polarizing beam splitter, (
50) (51) are 1/2 wavelength plates, (60) (60a)
(61), (62), (62a), and (63) are detectors, and (7) is a signal processing control circuit, respectively. Procedural amendment (voluntary) Amendment contents 16/1990 Page 20 of the specification of the Japanese application, lines 4 to 5, "Cylinderless (20) J" is replaced with "Cylinder lens"

Claims (5)

[Claims] (1) Two or more types of diffraction gratings with different lattice constants are arranged side by side on each of the first and second objects, and coherent light of two slightly different frequencies is irradiated to these diffraction gratings from the perpendicular direction, or ±n for each of these gratings
By irradiating from the following directions, detecting the ±nth order diffracted light generated from each of the diffraction gratings of the first and second objects, 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 diffraction or in the middle of the diffracted light optical path to generate optical heterodyne interference diffracted light, beat signals are generated based on these, and the above-mentioned diffraction gratings provided on the first and second objects are generated. A position detection method comprising: detecting the displacement amount of the first and second objects by measuring the phase difference of the beat signals obtained from the diffracted lights of the two objects having the same lattice constant. (2) 2 arranged side by side on each of the first and second objects
A diffraction grating consisting of more than one species of different lattice constants, 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 diffraction gratings of the first and second objects from ±n-order directions, and at the time when the irradiated light is diffracted by each diffraction grating; or an optical interference means that interferes two frequency components in the optical path of the diffracted light taken out in the vertical direction from each diffraction grating to produce optical heterodyne interference light; detection means for detecting the diffracted lights that are respectively taken out and turned into optical heterodyne interference light by the optical interference means to generate beat signals, respectively; It is characterized by comprising a signal processing means for measuring the phase difference of the beat signals obtained by the detection means from the diffracted light between the objects and detecting the displacement amount of the first and second objects based on these phase differences. position detection device. (3) 2 arranged side by side on each of the first and second objects
A diffraction grating consisting of more than one species of different lattice constants, a light source that generates coherent light of two slightly different frequencies,
Coherent light generated from the light source is transmitted to the first and second
a diffraction light extraction means for respectively extracting the ±nth order diffracted light among the diffracted lights generated from the diffraction gratings when the respective diffraction gratings of the object are irradiated from the perpendicular direction; Optical interference means for interfering frequency components to produce optical heterodyne interference light; and detection for generating beat signals by detecting the diffracted light extracted by the diffracted light extraction means and turned into optical heterodyne interference light by the optical interference means. and a beat signal obtained by the detecting means from the diffracted light of the diffraction gratings having the same grating constant among the diffraction gratings of the first and second objects. and second
A position detection device comprising: signal processing means for detecting the amount of displacement of an object. (4) 2 arranged side by side on each of the first and second objects
A diffraction grating having different grating constants of more than one species, a movement mechanism that moves the first object and/or the 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 diffraction gratings of the first and second objects from ±n-order directions, and at the time when the irradiated light is diffracted by each diffraction grating; or an optical interference means that interferes two frequency components in the optical path of the diffracted light taken out in the vertical direction from each diffraction grating to produce optical heterodyne interference light; detection means for detecting the diffracted lights that are respectively taken out and turned into optical heterodyne interference light by the optical interference means to generate beat signals, respectively; The phase difference between the beat signals obtained by the detection means from the diffracted light between the objects is measured, and a control signal is output to the moving mechanism based on these phase differences to move the first object and/or the second object. A positioning device characterized by having a signal processing control means that moves and performs positioning. (5) 2 arranged side by side on each of the first and second objects
A diffraction grating having different grating constants of more than one species, a movement mechanism that moves the first object and/or the second object, and a light source that generates coherent light of two slightly different frequencies;
Extracting diffracted light by extracting ±n-order diffracted light among the diffracted lights generated from the diffraction gratings of the first and second objects when the coherent light generated by the light source is irradiated from the perpendicular direction to each of the diffraction gratings of the first and second objects. means, an optical interference means for making two frequency components interfere with each other in the middle of the extraction optical path of each of the diffracted lights to produce optical heterodyne interference light; and an optical interference means for making optical heterodyne interference light extracted by the diffracted light extraction means and turned into optical heterodyne interference light by the optical interference means. Detection means for detecting diffracted light to generate beat signals respectively; and a phase difference between beat signals obtained by the detection means from diffracted light of the diffraction gratings having the same grating constant among the diffraction gratings of the first and second objects. and signal processing control means for measuring the respective phase differences and outputting a control signal to the moving mechanism based on these phase differences to move and align the first object and/or the second object. Alignment device.