JPS6258628A - Alignment process and device thereof - Google Patents

Abstract

PURPOSE:To perform the alignment of two members with diffractive grids with high precision by a method wherein two wavelength beams with slightly different frequency are entered into two diffractive grids arranged in parallel with each other to transmit the diffractive beams only exceeding one time diffraction. CONSTITUTION:Two kinds of beams with slightly different frequency emitted from a two wavelength orthogonal polarized laser beam source 33 passing through a beam splitter 21 and a condenser are inputted in a photodetector 25 to be transmitted to a signal processor 26 as reference beat signals. Besides, said beams are divided into two wavelength beams with slighly different frequency to be entered into a transmitted diffractive grid 29 and a reflected diffractive grid 30 at specified incident angle. Finally the diffractive beams from the grids 29, 30 are detected by a photodetector 25' to be transmitted to the signal processor 26 as diffractive beam beat signals. Through these procedures, the position slips can be detected referring to the phase difference from the reference beat signals.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a suitable alignment method and its implementation (user It concerns the alignment device used.

[Conventional technology]

With the miniaturization of semiconductor ICs and LSIs (C2), it is becoming increasingly difficult to use step and
In an apparatus that performs exposure and transfer using the rebeat method, it is essential to advance technology for aligning the mask and wafer with each other with high precision.

Conventionally, as a method for measuring minute displacements or precise positioning using optical heterodyne interference, there is a method that uses diffracted light from 12 diffraction gratings as shown in Fig. 4 (Japanese Patent Application No. 137,660/1982). .

In Fig. 4, 1 is a transmission type diffraction grating, 2 is a reflection type diffraction grating, 3 and 4 are incident lights whose frequencies are slightly C; two wavelengths are shifted, and 5.6 is the desired diffraction light, 3-1°4. -1 is the 1st-order transmitted diffracted light of the diffraction grating 1 Rikishima et al., 3-1', 4-1'
is the +1st-order reflected diffracted light of Shima et al. at the diffraction grating 2, 3-2.4
-2 is the +1st-order reflected diffraction light from the diffraction grating 2, and 7Fi is the 11th-order reflected diffraction light from the diffraction grating 2. The grating pitch P of the transmission type diffraction grating 1 is ten thousand times the grating pitch P2 of the reflection type diffraction grating 2, and P 2 =2 P 1 . In general, when a diffraction grating with a grating pitch P and an element with two wavelengths λ are vertically incident, the diffracted light is θ=ain-'(mu) (m=Q, 1.±2
It becomes strong only in the direction of , ・), and depending on the value, it is called the diffracted light of the order of the rising sun. In Fig. 4, let the two wavelengths whose frequencies are slightly shifted from each other be λ and λ2, and! The incident light beams 3.4 with wavelengths λ and λ2 are respectively incident from the direction of ], that is, the direction of the ±17 reflected diffracted light of the reflection type diffraction grating 2; therefore, p = −L
p, the reflected diffracted light from the transmission diffraction grating 1 is spatially separated with respect to the direction of the desired diffracted lights 5 and 6, that is, the vertical direction of the transmission diffraction grating. Further, the incident light 3.4 is diffracted by the transmission type diffraction grating IC and becomes 11th order transmitted diffraction light 3-1.4-1, respectively. Furthermore, the -1st-order over-diffracted light 3-1, 4-1 is diffracted by the reflection type diffraction grating 2 (Y) and becomes 11th-order reflected diffracted light 3-1'.

It becomes 4-1'. , the directions of incidence of the -1st-order transmitted diffraction light 3-1, 4-1 on the reflection type diffraction grating 2 are θ-1 and 4-1, respectively.
This is the direction of θ. The speed of light is C, the two wavelengths λ1, λ
If the frequencies of the two lights are respectively f, , f2, then the jIli wave number difference Δf1 between the two wavelengths, that is, the frequency of the beat signal, Δf has a value of about several KHz to several hundred MHz, and the older brothers C
It is sufficiently smaller than , and therefore λl~λ2. That is, θ
-0 -1 to +1 and the first-order reflected diffraction light 3-1'.

4-1' are each diffracted in the vertical direction of the diffraction grating 2, so they are optically combined, /'! The diffracted light 5 becomes r-inhibited. Furthermore, the incident light 3°4 is converted to 0 by the transmission type diffraction grating 1.
The next diffraction is reflected and diffracted by the reflection type diffraction grating 2, and +
The first-order reflection diffraction source becomes 3-2.4-2. The +1st-order reflected diffraction light 3-2, 4-2 is applied to the back surface of the transmission diffraction grating 1 in a direction relative to the vertical direction of the slope, that is, ± with respect to the slope of the transmission diffraction grating l.
Since the light enters from the direction of the first-order diffraction source, it undergoes first-order transmission diffraction by the transmission diffraction grating 1 to become vertically diffracted light, which is optically combined to form the desired diffracted light 6.

The phase of the beat signal due to optical heterodyne interference obtained from this diffraction i5.6 changes depending on the relative displacement between diffraction gratings 1 and 2. Therefore, two wavelengths of light similar to the incident lights 3 and 4 generated from the light source and incident on the diffraction bather 1.2 are branched out from the light source in advance, and the respective lights are combined to generate a beat due to original heterodyne interference. By configuring the optical system in such a way that a signal can be obtained, the reference fn and the diffracted light 5,
Positioning can be performed by detecting the phase difference with the beat signal of No. 6.

[Problem that the invention seeks to solve]

However, in this method, in addition to the diffracted lights 5 and 6 necessary for alignment, the incident light 3°4 is 0th-order diffracted by the transmission diffraction grating l and transmitted to the reflective diffraction grating 2 by d-1 and d, respectively.
The diffracted light is incident at an incident angle of +-1, and is optically synthesized by this diffraction grating 2 as the first-order reflected diffracted light in the vertical direction.
There is a diffracted light 7 which is diffracted in the O-th order by the transmission type diffraction grating 1, and since this diffracted light 7 occurs in the same direction as the desired diffracted lights 5 and 6, it causes interference. The diffracted light 7 is a composite diffracted light of the incident lights 3 and 4 that are diffracted and generated only by the diffraction grating 2, and like the diffracted lights 5 and 6, the diffraction grating 1 e 2 I: Therefore, the diffraction grating 1 e 2 I: This is different from the composite light of the double diffracted light of the incident light 3.4. That is, the diffracted light intensity of the diffracted light 7 is stronger than that of the diffracted lights 5 and 6C, which are double diffracted lights. The beat signal due to optical heterodyne interference obtained from this diffracted light f)h has the drawback that it does not cause a phase change in the relative displacement of the diffraction gratings 1 and 2 and cannot be aligned, or There is a drawback that the beat signal obtained from the diffracted light 5.6 and the beat signal obtained from the diffracted light γη interfere with each other, and the phase difference with respect to the first reference signal fluctuates, resulting in deterioration of accuracy.

The present invention was made in view of the above-mentioned circumstances ζ2, and its purpose is to make it possible to extract only desired diffracted light, obtain a stable bead signal, and improve positioning accuracy by [Means for solving the problem] The alignment method of the present invention consists in providing an alignment method and an alignment device used for implementing the method (2). Using a combination of diffraction gratings with a pitch of Pl and a grating pitch of the second diffraction grating fP2, the ±1st-order reflected diffraction light of each of the first and second diffraction gratings is At the time of death, two wavelengths of light with wavelengths λ1 and λ2 whose frequencies are slightly different from each other (ψ-100-1) are respectively (ψ-100-1).

This is a dead force method in which only the desired diffracted light is extracted and aligned by making it incident on the first and second diffraction gratings at an angle of (ψ+1+θ+1).

Further, the alignment device of the present invention includes a first object, for example, a first diffraction grating defined by a mask pattern Cfl, and a second object, for example, a wafer fixed to the first diffraction grating, which is fixed to the first diffraction grating at a constant distance from the first diffraction grating. a second diffraction grating that faces each other across, and a holding and moving mechanism that relatively moves the first object and the second object;
a light source that generates light of two wavelengths whose frequencies are slightly shifted from each other; a light combining means for extracting the diffracted light generated by the first and second diffraction gratings g2 and optically combining them; a detecting means for detecting an optical heterodyne beat signal of the combined diffracted light; and a detection signal by the detecting means. The holding and moving mechanism is equipped with a signal processing control means that sends out a control signal to align the first object and the second object to the correct positions in response to the movement.

[Operation] According to the method of the present invention, for the desired diffracted light, the reflected diffracted light from the first diffraction grating of the incident light in the same direction as the desired diffracted light, and the O-order transmission of the incident light by the @1 diffraction grating. The diffracted light is reflected and diffracted by the second diffraction grating, and the diffracted light is further diffracted by the first diffraction grating again through the 0th-order transmission, and the diffracted light is separated into nine parts.

In addition, in the apparatus of the present invention, by adjusting the incident angle of the incident light to a desired angle txt:=,+i using the incident angle adjustment means, only the desired diffracted light is generated, and the light of this combined diffracted light is The heterodyne beat signal is input to the signal processing control means via the detection means to operate the holding and moving mechanism.

[Example] The present invention will be explained below based on the drawings.
Present invention C; one embodiment of such a positioning device, namely:
This is an overview of the four types of X-ray equipment used to manufacture semiconductor ICs and LSIs. In Figure 1, 33
have frequencies that differ from each other by only l2, and polarization plane directions that differ from each other by t.
A two-wavelength orthogonal polarized laser light source (light source) that emits light of two orthogonal wavelengths, 21 is a beam splitter, 22,
22' is a condensing lens, 23.23', 23'',
23" is a baler (however, the balers 23' and 23" are adjustable in angle yA) 24 is a polarizing beam streak 11 - 125,
25' is a photodetector, 26ti signal processing control &+S (signal processing control means), 27 is a mask stage, 28 is a mask (first object), 29 is a transmission type diffraction grating (C first diffraction grating), 30Fi, reflection type diffraction grating (second diffraction grating),
31 is a wafer (second object/body), and 32 is a wafer stage.

In Fig. 1, a part of the light emitted from the two-wavelength orthogonally polarized laser light source 33 is taken out through the beam splitter 21, passed through the condensing lens 22, and detected by the photodetector 25. On the other hand, the light emitted from the orthogonal polarized laser beam 13 1) From 241 m of ivy, the light beams are divided into π-ray polarized light having only horizontal or vertical components, each having a length of 2ffJ, regardless of the number of beams.
Mirror 23', respectively.

The light is incident on the transmission type diffraction grating 29, the outside and the reflection type diffraction grating 30+- at a desired angle of incidence via 23# (incident angle adjusting means). The nine diffracted lights obtained from the diffraction grating 29 and 30 are reflected into the mirror 2.
3" (photosynthesizing means), a photodetector 25' (detecting means) through a condensing lens 22', detecting a diffracted light beam)
- Signal processing fee yJ agent 261 = input as a signal. The M processing control section 26 detects the phase difference between the reference beat signal and the diffracted light beat signal, controls the C knee nose holder moving mechanism (not shown) so that the phase-a difference becomes 06, and moves the mask stage. 2
7, and the wafer 32 are moved relative to each other, and the exposure can be performed with precision (t) by pressing a button on the mask surface or at a predetermined position on the wafer surface. Next, the positioning method of the present invention will be explained using the positioning device configured as described above.

In Fig. 2, 8 is a single-pass diffraction grating, 9 is a reflection grating, 10.11 is incident light with two wavelengths slightly different from each other, 12.13 is a desired diffracted light, and 10-1
．． 11-1 is the 11th-order transmitted diffraction light from the transmission type diffraction grating 8, 10-1', 11-1' is the 1st-order reflected diffraction light from the reflection type diffraction grating 9 Rikishima et al., 10-2.11-2 is the 11th order reflected diffraction light from the reflection type diffraction grating 9. The grating pitch P1 of the transmission type diffraction grating 8 is ten thousand times the grating pitch P2 of the reflection type diffraction grating 9. Using the incident angle adjusting means, the incident direction of the incident light 10.11 is set perpendicular to the diffraction grating surface, and the angles of ± and (ψ) of the diffraction gratings 8 and 9 are adjusted.
, 10 + 1 ) angle f, (; Set.

Here, the wavelengths of the incident light 10.11 are λ and λ2,
The frequency difference Δf is a value ranging from several KHz η to several hundred MHz, which is much smaller than the speed of light C2, and the ±1st order diffraction angles for the two wavelengths λ1 and λ2 are almost equal. Therefore, ψ−〜−ψ+1゜θ−1da θ+1
Then, (ψ-, + 0.-1) ~ - (ψ, 10+1). Grating pitch P of diffraction grating 8°9
, P is P2=2P1, and the angle of incidence of l 2 incident light 10.11 is (ψ-5+ θ-1)-(
By setting ψ+1 10+1 ), the reflected diffracted light from the diffraction grating 8 for the incident light 10 and 1142 is directed in the direction of the desired diffracted light 12.13, that is, in the vertical direction of the diffraction grating surface. separated spatially.

In addition, as shown in Fig. 2, (-1 diffraction/grating 8°9 (-) the incident light 10.11 is transmitted through the transmission type diffraction grating 8.
The first-order transmitted diffracted light becomes 10-1.11-1, and has an incident angle of θ-11θ.

Each of them enters the reflection type diffraction grating 9, where they are each reflected and diffracted to become 11th-order reflected diffraction light 10-1'.

11-1'. -1st order reflected diffraction light 10-1'.

11-1' is the diffracted light that is diffracted in the vertical direction of the diffraction grating, and the optical f;
The light is subjected to zero-order transmission diffraction and becomes the desired diffracted light 12.

On the other hand, a part of the incident light 10.11 that has entered the diffraction grating 8.9 is transmitted through the iζ type diffraction grating 8C; therefore, it is subjected to zero-order transmission diffraction and enters the reflection type diffraction grating 9, where it is reflected and diffracted. The 11th-order reflection diffraction particles 10-2 and 11-2 are incident on the transmission type diffraction grating 8 at human incidence angles ψ and ψ, respectively. −
The 1st-order −1+1 reflected diffracted light 30-2 and 11-2 are transmitted and diffracted by the transmission type diffraction grating 8, and are optically synthesized as 11th-order transmitted diffracted light in a direction perpendicular to the diffraction grating 8, thereby producing a desired diffracted light. 13
becomes. In other words, the diffracted light in the desired direction is not other than the desired diffracted light 12.13 (the reflected diffracted light obtained by diffracting the incident light 10.11 by the wave-type diffraction grating 8, and the incident light 10.11). is spatially separated from the diffracted light which is transmitted and diffracted by the transmission type diffraction grating 8, reflected and diffracted by the reflection type diffraction grating 9, and again transmitted and diffracted by the transmission type diffraction grating 8G2. Supplementary photodetector 25'3:
A beat signal due to heterodyne interference (;) is detected from the desired diffracted light 12, 13, and the phase difference with reference No. 16 is measured to align the mask 28 and the wafer 31.

On the other hand, FIG. 3 is a diagram showing the milk fraction of the diffraction grating in another embodiment of the apparatus of the present invention. Refer to figure 3, 14.
14', 14'' are the mirrors, 15 is the polarizing beam splitter, 16, 16' is the polarizing plate, 17 is the incident light, 17-1.
17-2.17-3°17-4.17-5.17-6.
17-5'.

17-6', 17-7.17-8.17-9 is the diffracted light, 18.19 is the desired diffracted light, 20.20' is the sky 1'
It is a Jf filter. The incident light 17 has two wavelengths λ4. This light is a composite light of λc, and is a linearly polarized light whose planes of polarization are perpendicular to each other. As shown in FIG. 3 (2), the incident light 17 entering from the vertical direction of the diffraction grating 8.9 is transmitted and diffracted by the transmission type diffraction grating 8, and the 0th order transmitted diffracted light 17
-9 enters the reflection type diffraction grating 9 from the vertical direction of the diffraction grating, and +1st-order transmitted diffracted light 17-1. The -1st-order transmitted diffraction light 17-2 is incident on the reflection type diffraction grating 9 at an incident angle of ψ-2 or ψ. The 0th-order transmitted diffraction light 17-9 is reflected and diffracted by the reflection type diffraction grating 9 at an angle of θ21 or θ+1, and becomes the 11th-order reflected diffraction light 17-3. +
This becomes first-order reflected diffraction light 17-4. Furthermore, the −1st-order reflected diffraction light 17-3, 17-4 is filtered by the transmission type diffraction grating 8 (
ψ-710-ff) is transmitted and diffracted at an angle of (ψ, 10, etc.) and the +1st-order transmitted diffracted light 17-7.
17-8. On the other hand, ±1st-order 'fh overdiffracted light 17-1
．． 17-2 is a reflection type diffraction grating 9, (ψ-7+θ
-7) or (ψ, 10, etc.) angle (-diffracted and becomes +1st order reflected diffracted light 17-5', 17-6',
The light is further diffracted by the 0th order by the transmission type diffraction grating 8c to become 0th order transmitted diffracted light 17-5 and 17-6. Diffraction grating 8.9
Diffracted light 17-15.17-6.17-7 generated by
．． 17-8 is a spatial filter 20°20', mirror 1
4.14' to the polarizing beam splitter 153. Diffracted light 17-5°17-6.17-7.17
-8 is the composite light of two wavelengths of λ1 and λ2, respectively,
This is light with M polarization whose planes of polarization are perpendicular to each other. Polarizing plate 16
．． 16' for the diffracted light 17-5.17-7 and the diffracted light 17-6.17-8 respectively, the horizontal polarization component of the light, i.e. the light of wavelength λ, (or λ2), and the vertical polarization component of the light. , i.e. the wavelength λ2 (or λ,)
By taking out the light and making it incident on the polarized beam filter 15, it is possible to take out the desired diffracted light 18.19, which is optically combined light of two wavelengths λ1 and λ2. Positioning can be performed by detecting a beat signal caused by optical heterodyne interference from the desired diffracted light 18.1C1x.

In the above explanation, the grating pitch P of the transmission type diffraction grating 8 was set to 1/2 of the grating pitch P2 of the reflection type diffraction grating 9, but in general, the grating pitch P of the transmission type diffraction grating is set to 1/2 of the grating pitch P2 of the reflection type diffraction grating. - (n is a positive integer) of the lattice pitch P2], that is, p, = -Lp2

n, set the vertical direction of the diffraction grating surface as the direction of 0th order diffraction, and set it to the incident direction or the direction of the desired diffracted light, and set the direction of ±1st order diffraction of the transmission type diffraction grating to ψ-1°9.Reflection type 6 = the direction of the ±1st order diffraction of the diffraction grating.

+“l θ+1, (ψ−100−1) and (ψ+1
If the direction of 10+1) is set as the desired diffracted light direction or incident direction, the reflected diffracted light of the incident light from the transmission type diffraction grating and the O-th order diffracted light of the incident light from the transmission type diffraction grating will be reflected type. The diffracted light that is reflected and diffracted by the diffraction grating and then transmitted and diffracted by the transmission type diffraction grating does not produce the originally desired diffracted light direction 4, allowing highly accurate positioning.

In addition, in FIG. 1, a pair of diffraction gratings 29°30f
Diffraction gratings similar to those shown above are installed at two or more positions on the mask and wafer surface, and the beat signal of the diffracted light is detected using the same method as in Figure 1, and the phase difference with the reference signal is detected. (-By controlling the mask and wafer stage, the mask and wafer are aligned in two axes, X and Y, parallel and perpendicular to the diffraction grating in a plane parallel to the diffraction grating plane.
, and the rotation axis θ of the XY plane centered on the z-axis perpendicular to the XY plane.

Further, as the first and second diffraction gratings in the present invention, either an absorption type diffraction grating or a phase type diffraction grating may be used. , blazed diffraction grating, etc. are possible.

In addition, in this implementation example, the diffraction grating f in z))2 is described in 1 C and 9 above, but the same effect can be obtained when a transmission type diffraction grating is used. Obtainable.

Furthermore, in the embodiment of the present invention, the grating pitch P11 of the first diffraction grating: whereas the grating pitch P2 of the second diffraction grating
Although we have discussed the case where ntPt is doubled, in general, ntPt
A similar effect can be obtained when using a diffraction grating with a grating pitch having the relationship of == r12P2 (n, e T: 12 is a positive integer). 4. [Effects of the Invention] As explained above, 2. According to the method of the present invention, an alignment device (-
In this case, only one of the transmission type diffraction grating and the reflection type diffraction grating (-Therefore, the relative displacement between the mask and the wafer caused by the first-order diffraction (2) can be removed. Precise alignment can be stably performed, and it is extremely effective for highly accurate alignment of masks and wafers.However, the method of the present invention is useful not only for alignment, but also for It can also be applied to devices that measure all minute displacements, coordinate position detection, and control devices.

Further, according to the apparatus of the present invention (:), the incident angle of the incident light can be adjusted to a desired angle (i.e.,
), (ψ+100+, ) or the vertical direction of the diffraction grating)
This allows for highly accurate positioning by extracting only the desired diffracted light.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one example of the present invention.
The figures are the same (ii of the diffraction grating, (schematic diagram showing 1 minute, 3rd
This figure is a schematic diagram showing a portion of a diffraction grating in another example of back-relaxation of the present invention, and FIG. 8... Transmission type diffraction grating, 9... Reflection type diffraction grating, 10.11... Incident light, 10-1.
11-1...11th-order transmitted 11th-order diffracted light from the transmission type diffraction grating 8, 10-1', 11-1'...11st-order reflected diffracted light from the reflection type diffraction grating 9% 1o-2, 11-2
...11th order reflected diffraction light from the reflection type diffraction grating 9, 12
．． 13... Desired diffracted light, 14.14',
14"...Mirror, 15...1 Optical beam splitter-116°16'...Polarizing plate, 1
7...Incoming light, 17-1°17-2.17-3
．． 17-4.17-5.17-6.17-5', 1
7-6', 17-7.17-8... Diffracted light, IF3.19... Desired diffracted light, 20.20
'...Spatial filter, 21...Beam splitter, 22, 22'...Condenser lens, 23.23''...Mirror, 23' +
23”-・---・mirror (incidence angle - small degree), 24・
...A optical beam splitter-125...
Photodetector, 25'...Pop detector (detection means)
, 26... Signal processing ■(! Leg (signal processing control means), 27... Mask stage, 28...
...Mask (f41 object), 29... Growth type diffraction grating (first diffraction grating), 30... Reflection type diffraction grating (second diffraction grating), 31 . . . wafer lT2 object), 32 . . . wafer stage, 33 . . . 2 wavelength orthogonal polarization laser source (light source). /ill Application Nippon Telegraph and Telephone Corporation Representative Patent Attorney Masaru Shiga Takeshi 23゛, 23” Person 1 Shusei Yui ■Mata (Miller) 28
: 1st/l hook stop (enter Y) 29 : 1st round answer (number for 1st page of temptation) 30
Tail 2/1st Yuju1su (about 11th first J save) 26
゛ 1 old issue ↓ Weekly Cancer '1911 La- (I old 'g
j mesako! 2nd figure 9: M2 〆) times 1 completed y+h (7 anti↓ hiko type 1 times ding q℃ child itran 3rd figure 4th figure 7.

Claims (1)

[Claims] 1) A first diffraction grating provided on a first object and a second diffraction grating provided on a second object can be moved in parallel with each other by facing each other with a fixed interval between them. monochromatic light is incident on the first and second diffraction gratings, and the relative displacement of the first object and the second object is detected and aligned using the diffracted light generated from both diffraction gratings. In the method, light of two wavelengths whose frequencies are slightly shifted is used as the monochromatic light, and the first
Out of the diffracted lights generated by the first and second diffraction gratings, only the diffracted lights that have been diffracted to the first or higher order by both diffraction gratings are taken out, and these are optically combined to form an optical heterodyne beat. A positioning method characterized by generating a signal and detecting a relative displacement between a first object and a second object based on a phase change of the signal to align the two objects. 2) A patent claim characterized in that the incident light incident on the first and second diffraction gratings is linearly polarized light having two wavelengths whose frequencies are slightly shifted and whose planes of polarization are perpendicular to each other. The alignment method described in item 1. 3) In an apparatus for relatively aligning a first object and a second object, a first diffraction grating fixed to the first object and a first diffraction grating fixed to the second object and the first diffraction grating fixed to the first object; A second diffraction grating that faces the grating at a constant interval, a holding and moving mechanism that relatively moves the first object and the second object, and light of two wavelengths whose frequencies are slightly shifted from each other. a light source that generates light, an incident angle adjustment means that adjusts the incident angle of the two wavelengths of light that enters the pair of first and second diffraction gratings from the light source, and a light source generated by the first and second diffraction gratings. a photosynthesis means for taking out the diffracted lights and optically combining them;
a detection means for detecting an optical heterodyne beat signal of the combined diffracted light; and a control signal is sent to the holding and moving mechanism in response to the detection signal from the detection means to relatively move the first and second objects to a predetermined position. A positioning device comprising a signal processing control means for positioning the position.