JPH04204308A - Position detecting device - Google Patents

Abstract

PURPOSE:To eliminate the influence of error factors so as to enable the detection of both relative position with high accuracy by referring a preacquired general formula of a position information concerning both body to respective position information, detected, actually of two bodies. CONSTITUTION:Physical optical elements Z1 to Z4 are respectively provided on the surface of a body 1 and on the surface of a body 2, a sensor 3 detects position information of a diffracted light flux caused by an incident light flux onto these elements Z1 to Z4. The relationship between the relative displacement quantity 'w' at a relative gap 'g' between a body 1 and a body 2 and the position information detected with a sensor 3 is experimentally obtained in advance to record it in a recording means as a general formula. Next, in an actual position detection, referring to the general formula in the recording means, two values between diffracted light fluxes, being related to both the relative displacement quantity 'w' between the body 1 and the body 2 and the relative gap 'g' therebetween, among three diffracted light fluxes, are detected to calculate the displacement quantity 'v' and the gap 'g' are calculated, so that the error factors are eliminated to enable highly accurate and easy positioning can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a position detection device, and for example, in an exposure apparatus for manufacturing semiconductor elements, the present invention relates to a position detection device that detects a position on a first object surface such as a mask or a reticle (hereinafter referred to as "mask"). This invention relates to a position detection device suitable for performing relative positioning (alignment) between a mask and a wafer when exposing and transferring a fine electronic circuit pattern formed on a second object surface such as a wafer. .

(Prior Art) Conventionally, in exposure apparatuses for semiconductor manufacturing, relative alignment between a mask and a wafer has been an important element for improving performance. Particularly in alignment in recent exposure apparatuses, alignment accuracy of, for example, submicron or less is required due to the high integration of semiconductor devices.

In many alignment devices, a so-called alignment pattern for alignment is provided on the mask and the eight faces of the sea urchin.
Alignment of both is performed using the position information obtained from them. As an alignment method at this time, for example, the amount of deviation between both alignment patterns may be detected by performing image processing, or U.S. Pat.
As proposed in No. 037969 and Japanese Unexamined Patent Publication No. 56-157033, a zone plate is used as an alignment pattern and a light beam is irradiated onto the zone plate. This is done by detecting the position.

In general, alignment methods using zone plates are
Compared to a method using a simple alignment pattern, this method has the advantage of being able to perform alignment with relatively high precision without being affected by defects in the alignment pattern.

FIG. 6 is a schematic diagram of a conventional alignment device using zone plates.

In the same figure, a parallel light beam emitted from a light source 72 passes through a half mirror 74 and is condensed at a condensing point 78 by a condensing lens 76, after which it is placed on a mask alignment pattern 68a on the surface of a mask 68 and on a support base 62. The wafer alignment pattern 60a on the surface of the wafer 60 is irradiated. These alignment horns 68a and 60a are composed of reflective zone plates, each forming a focal point on a plane perpendicular to the optical axis including the focal point 78. At this time, the amount of deviation of the focal point position on the plane is detected by guiding the light onto the detection surface 82 using the condensing lens 76 and the lens 80.

Based on the output signal from the detector 82, the control circuit 8
4 drives the drive circuit 64 to perform relative positioning of the mask 68 and the wafer 60.

Figure 7 shows mask alignment pattern 6 shown in Figure 6.
8a and an explanatory diagram showing the imaging relationship between the light beams from the wafer alignment pattern 60a and the wafer alignment pattern 60a.

In the figure, a part of the light beam diverging from the condensing point 78 is diffracted by the mask alignment pattern 68a,
A focal point 78a indicating the mask position is formed near the focal point 78. Further, the other part of the light beam passes through the mask 68 as zero-order transmitted light and enters the wafer alignment pattern 60a on the surface of the wafer 60 without changing its wavefront. At this time, the light beam is diffracted by the wafer alignment pattern 60a, and then passes through the mask 68 again as zero-order transmitted light, condensing near the converging point 78 and focusing on the wafer position.
form. In the figure, when forming a focal point for the light beam diffracted by the wafer 6o, the mask 68 acts as a mere transparent state.

The position of the focal point 78b due to the wafer alignment pattern 60a formed in this manner is determined by the displacement amount Δσ of the wafer 60 with respect to the mask 68 along a plane perpendicular to the optical axis including the focal point 78. It is formed as a deviation amount Δσ' corresponding to the amount Δ0.

Conventionally, the mask 68 and the wafer 60 have been aligned by comparing the amount of deviation Δ0' at this time.

(Problems to be Solved by the Invention) The positioning apparatus shown in FIG. 6 involves an uncertain amount of the distance g between the mask and the wafer, which causes the following problems, for example.

Since the deviation amount Δσ' is dependent on both the deviation amount Δσ and the interval g, one deviation amount Δ0' corresponds to several sets of the deviation amount ΔO and the interval g. For this reason, when trying to detect a matching state at the position of the focal point 78a, if the light beam is focused at the position of the focal point 78b when out of focus, the value of the deviation amount Δa' cannot be accurately determined. Even if measured, the amount of deviation Δσ cannot be accurately determined. For this reason, although it would be sufficient to perform the alignment operation once, it becomes necessary to perform the alignment operation two or three times, resulting in a decrease in throughput.

The present invention solves the error factors that occur when detecting the position of a first object such as a mask and a second object such as a wafer, and provides position detection with a simple configuration that allows for highly accurate and easy alignment. The purpose is to provide equipment.

(Means for Solving the Problems) The present invention calculates the amount of relative in-plane positional deviation between a first object and a second object (hereinafter also simply referred to as "the amount of deviation"), and at the same time calculates the interval. It is characterized in that the positions of the object and the second object are determined with high precision.

In particular, in the present invention, physical optical elements are provided on the first object plane and the second object plane, and position information of a diffracted light beam of a predetermined order generated on a predetermined plane of the light beam incident on these physical optical elements is obtained. When detecting the relative positions of the first object and the second object by detecting them with the detection means, the relative displacement amount W in the relative distance g between the first object and the second object is determined. , with reference to the recording means that has experimentally determined and recorded the relationship with the positional information y detected by the detection means, among the at least three diffracted light beams generated on a predetermined surface by the detection means. Relative shift amount W between the first object and the second object
The present invention is characterized in that at least two values between the diffracted light beams related to both the and the relative distance g are detected, and the deviation amount W and the distance g are determined by the calculation means using the output signal from the detection means. .

For example, position information y obtained by the detection means at a known relative distance g between the first object and the second object and a known relative shift amount W is combined with a large number of distances g and shift amounts W. These three elements g,
A general formula (experimental formula) regarding w and y is determined and recorded in a recording means.

When determining the amount of deviation W and the interval g from the output signal obtained from the detection means, the general formulas recorded in the recording means are used to determine them.

(Embodiment) FIG. 1 is a schematic diagram of the main part of a first embodiment of the present invention, and FIG. 2 is a schematic diagram of the main part when the optical path of each light beam in FIG. 1 is expanded.

1st. In FIG. 2, Ill is a light beam from a semiconductor laser, SLD, or X-ray source (not shown), and is incident at an angle θ to physical optical elements zl and z3, which will be described later, on the surface of a first object such as a mask. . Reference numeral 2 denotes a second object such as a wafer, which is placed opposite to the first object 1 at a distance g. W is first
It shows the relative shift amount between the object 1 and the second object 2.

zl and z3 are the transmission-type first
．． It is a third physical optical element, and the light beam 11 is a physical optical element z.
It is incident on l and z3. z2゜z4 is a reflective type (shown as a transmissive type in FIG. 2) provided on the second surface of the second object.

) No. 2. The fourth physical optical elements 21 to Z4 are composed of, for example, a diffraction grating or a zone plate.

FIG. 3 shows an example of the pattern of the physical optical elements on the surfaces of the first object 1 and the second object 2 according to this embodiment.

The physical optical elements 21 to z4 have a lens function, and their focal lengths are f1 to f4, respectively.

IL2 to it9 are diffracted lights of a predetermined order from the physical optical elements, and 3 is a detection means such as a line sensor or an area sensor, which is disposed as far away as the distance from the first object 1. at and C2 are respectively physical optical elements zl,
z3, of which the optical axis a1 and the optical axis a2 are separated by a distance.

Points C1 to C4 are respectively diffracted lights j23. It5゜It
7. This is the center of gravity of the light beam on the third surface of the μ9 sensor. Among these, points CI and C2 are at distances yl and y2jl from the optical axis a1, respectively.
Points C3 and C4 are respectively distances y3 and y3 from the optical axis a2. y411f indicates the position.

For convenience, the center of gravity of the luminous flux is the point within the cross-section of the luminous flux where, when the product of the position vector from each point of the cross-sectional circle multiplied by the light intensity at that point is integrated over the entire cross-section, the integral value becomes 0 vector. It shows.

4 is a signal processing circuit as a calculation means, and based on information from the sensor 3, the luminous flux u3. The center of gravity of the luminous flux of j25°I17 and 19 is determined.

At this time, in this embodiment, the distance between the first object and the second object is g.
Sensor 3 for diffracted light of a predetermined order for the amount of slippage W when
The relationship between the incident position information y on the surface is determined experimentally in various cases and a general formula is created. And at this time-
The formula is recorded, for example, in a recording means provided as a part of the calculating means 4 or in a statement recording means (not shown) provided outside. And distances y1 to y'1, which are positional information. D is recorded on the recording means.

The amount of positional deviation W and the distance g between the first object 1 and the second object 2 are determined using the general formula. Reference numeral 5 denotes a control circuit, which controls the amount of positional deviation W and the distance g between the first object 1 and the second object 2 in accordance with information regarding the amount of positional deviation W and the distance g from the signal processing circuit 4.

Reference numeral 6 denotes a stage controller, which drives a stage (not shown) on which the second object 2□ is mounted in accordance with instructions from the control circuit 5.

In this embodiment, the light beam ρ1 from the light source is incident on the physical optical elements zl and z3 on the first object 1 surface, respectively. Among these, the first-order diffracted light J22 generated in the physical optical element z1 of the light beam J21 that has entered the physical optical element z1 enters the physical optical element Z2. Then, a first-order diffracted light fL3 having a different diffraction direction depending on the positional deviation amount W is generated. The diffracted light 13 passes through the physical optical element z1 as it is as O-order diffracted light. The diffracted light j23 forms an image on the surface of the sensor 3 at a distance yt from the optical axis a1. Since the distance between the sensor 3 and the first object 1 is a constant value, the value of the distance y1 depends on the distance g and the positional deviation amount W.

On the other hand, the light beam j21, which has passed through the physical optical element Z1 as a 0th-order diffracted light without undergoing any diffraction effect, is incident on the physical optical element Z2. Then, the first-order diffracted light that has undergone the first-order diffraction effect in the physical optical element z2 enters the physical optical element z1 again. Then, first-order diffracted light 15 whose diffraction direction differs depending on the positional shift amount W is generated. The first-order diffracted light, I25, forms an image at a distance My2 from the optical axis a1 on the surface of the sensor 3.

From the light beam 11 that entered the physical optical element Z3, the light flux that entered the physical optical element z1, diffracted lights 16 to 19 similar to Ct.
are generated, and among these, the diffracted lights f7°19 are each at a distance y3. The images are respectively formed at the y411 positions. 4 is a signal processing circuit as a calculation means, and from the information read from the sensor 3, the luminous flux IL3. J
25. Light flux gravity center position CI of u7゜j29, C2, C3,
After finding C4, the distance D14 between point CI and point 04, point C
2 and point C3 is calculated. The positional deviation fiW and the distance g between the first object 1 and the second object 2 are determined by using the relationship between the values of the distance D14 and the distance D23 in various equations to be described later.

The control circuit 5 drives the stage controller 6 in accordance with the information regarding the positional deviation amount W and the interval g from the signal processing circuit 4 to move the second object 2 to a predetermined position.

In this embodiment, the diffracted light is limited to the first-order diffracted light, but the same effect can be obtained by using second-order or higher-order diffracted light.

In this embodiment, the light source, sensor, etc. can be assembled in one place, so the optical probe can be miniaturized, and since the optical probe does not need to be moved during exposure, the throughput is further improved. have.

Next, how to determine the positional deviation amount W and the distance g between the first object 1 and the second object 2 in this embodiment will be explained with reference to FIG.

In the lens system that generates the diffracted light 13 in FIG.
passes through and enters point C1. At this time, the distance y1 of the diffracted light I13 to the center of gravity C1 of the light flux is determined by the amount of slippage W between the first object 1 and the second object 2 and the distance g, and is generally:! /1=F1 (W, g) −・・・・・・・・
...It is expressed as (1).

Similarly for the other three lens systems, the distance y2. y3.
y4 is an amount determined by the amount of deviation W and the interval g, and y2=F2 (W, g) ・・・・・・・・・・・・
-(2)y3=F3 (W, g)...
・・・・−(3) y4=F4 (w, g) ・・
It is expressed as (4).

When the distance 11fyl to y4 is expressed as above, the point C
Distance D13 between point 1 and point 03 and interval D between point C2 and point C4
24, quantities Yl and Y2 that depend on the amount of rubbing W and the distance g can be expressed as follows.

Yl-yl+y3-D13-D-F1+F3-F5 (
Jg) Y2-, y2+y4-D24-D-F2+F4・
F6 (W, g), that is, Y1=F5 (W, g) ・・・・・・・・・
...(5) Y2=F6 (W, g) ++...
・・・・・・・・・(6) Generally, when there are two unknowns,
If you have two equations that include unknowns, you can find the solution to the unknowns.

That is, A=01 (W, g)...
・−(7)B=02 (W, g>'−・・
・・・・・・・・・If you can prepare two relational expressions like (8), 2 can be obtained by finding the quantities A and B by measurement etc.
It is possible to find the value of the two unknowns W9g.

When the above-mentioned formula (1) is specifically expressed using w and g, for example, in terms of paraxial geometric optics, it is as follows. From Figure 2, y 1 :W=L+2g-f 1 :
f 1-g From this. The other equations (2), (3), and (4) are similarly obtained. Based on the above relational expressions, (5), (6)
The formula can be expressed concretely as follows. In equations (13) and (14), the distance between the optical axis a1 and the optical axis a2 is known, and the values of the distance D13 and the distance D24 can be specifically determined by measurement, so (13) , The values of the deviation amount W and the interval g can be obtained from equation (14). By eliminating the deviation amount W from equations (13) and (14), a cubic equation for the interval g is obtained,
From this equation, the amount of deviation W and the interval g can be easily determined using a computer or the like.

In this example, the first to fourth physical optical elements 21 to Z
The four focal paths 11fl to f4 are set to satisfy the following equation.

f3+g L+g f4 Or It is set as follows.

On the other hand, the above-mentioned equations (9) to (12) hold true within the range of accuracy that can be handled by paraxial geometric optics. However, for example, when the alignment force is about 10.01 μm, there are aberrations in the detection system, manufacturing errors during lens processing, errors during assembly and adjustment, and the semiconductor laser and SL due to aging.
This is not necessarily true in general due to error factors such as fluctuations in the oscillation wavelength of D and movement of the light emitting point.

Therefore, in this embodiment, in order to deal with these error factors, the relationship between the positional deviation W at the interval g and the distance Y based on the incident position of the light beam on the sensor surface is examined in various cases. General formulas corresponding to the above-mentioned formulas (1) to (4) are determined and recorded in the recording means.

When actually detecting the position, a general formula recorded in the recording means is used.

Furthermore, by updating the general formula obtained every certain period, error factors that occur due to changes over time are dealt with.

The general formula in this embodiment includes, for example, the above-mentioned interval g, positional deviation amount W, and distance y using six coefficients A and B.

Use E, F, I, J'! −(Ag+B)W2+ (Eg+F)W+ (Ig
+J) -- It is expressed by the formula (15). Then, take at least 6 pieces of data for each luminous flux, coefficient A,
B, E, F.

1. Determine J.

When collecting data at this time, a tool is prepared in advance that has accurately measured the amount of deviation W and the distance g between the mask and the sea urchin.

Further, the value of distance y may be determined as a distance from an arbitrary point on the sensor.

This is because by finding the sum or difference of y1+y2, etc., the accurate distance between each light beam can be found.

Then, the distance g and the positional deviation amount W are determined as follows.

First, let us assume that the equations corresponding to the above-mentioned equations (5) and (li) are found as follows.

yl= (8+g+8+)W2+(E+g+F+)W+
(1+g+, I+) ”'(16)y2・(A2g
+82)W2+(E2g+F2)W+(hgsu,) ・
... (17) (15) If we rewrite equation (+7) in terms of g, we get yD (A+W2+E+Wbow+)g” (B+
W"FtW"J +) "' (18)y2・
(＾2i12÷E2W+h)g”(B2W2+F2訃J
2) ...(19). (+8) , (19
) The value of W is determined from the quadratic equation for the amount of positional deviation W, which is determined from the equation, and the value of the interval g is determined from this.

FIG. 4 shows the diffracted light beam J23°+5. ff
17. FIG. 9 is an explanatory diagram showing how the center of gravity of the +9 light beam C1, C2, C3° C4 changes on the surface of the sensor 3 according to the amount of deviation W; Diffraction beam J23. +15. +7. +
9 etc. have a certain width on the sensor surface, so if there are parts that overlap each other, it becomes difficult to accurately determine the points C1 to C4.

Therefore, in this embodiment, when it is desired to measure within the deviation amount W = ±3 μm, for example, the characteristics of the range where each luminous flux is far apart (for example, between point WO-3 and point W o + 3 in Fig. 4) are simulated in advance. etc., and use this.

That is, in this embodiment, the first. The first . The barycenter position of the second two diffracted light beams and the third. A third . The positions of the centers of gravity of the fourth two diffracted light beams are detected in a state where they are separated from each other by at least the width of the diffracted light beams.

In this embodiment, when the positional deviation amount W between the first object and the second object is 0, the physical optical element (for example, zl
) and the physical optical element (for example, z2) on the second object.
) by shifting the optical axis a2 by a distance HWO,
When the amount of positional deviation W between the first object and the second object is 0, point C
1 and point C2, and point C3 and point C4 can be kept apart.

The pattern arrangement of the first to fourth physical optical elements 21 to Z4 shown in FIG. Element Z1
The optical axes of and z2 are also connected to the third and fourth physical optical elements z3 and Z4.
The optical axes of each are set to be shifted by a distance MWO.

Therefore, when this pattern is used, when the first object and the second object are deviated by a distance Ill W x, (9) ~ (
12) Calculation may be performed by replacing the value of the deviation amount W in the equation with W = W o + W x .

Note that in this embodiment, the first. Instead of providing two physical optical elements on each of the second object planes, four physical optical elements are provided on one object plane, and the above-mentioned diffracted light beams fi3, 15. ff1
7. A similar effect can be obtained by obtaining four diffracted lights corresponding to n9.

However, the method of providing two physical optical elements as in this example requires less area than the method of providing four physical optical elements, and when comparing the same area, the amount of diffracted light is 2.
There are twofold advantages. Next, other embodiments of the present invention will be described in order.

(B) Second Example In the first example, the deviation jlW and the interval g were determined from the combination of the distances y1 and y3 and the distances 111y2 and y4, but the distances y1 and y4
, distances 11y2 and y3, distances 11yl and y2, and distances y3 and y4.

When distances y1 and y4 and distances y2 and y3 are combined, point C1
Assuming that the distance between C4 and C4 is D14, and the distance between C2 and C3 is D23, an equation corresponding to equation (7) and (8) can be expressed as follows.

・・・・・・・・・(21) Similarly, when the distances 11yl and y2 and the distances 111y3 and y4 are combined, the distance between points C1 and C2 is D12, and the distance between points C3 and C4 is D34. Then......(23
) becomes. From these equations, the amount of deviation W and the distance g can be determined.

Incidentally, the amount of positional deviation W and the distance g can be similarly determined from general equations corresponding to equations (20) to (23) obtained from the above-mentioned experimental data.

(b) Third embodiment 1. In the second embodiment, the light beam gravity center position CI of the four light beams,
Using C2, C3, and C4, formulas corresponding to formulas (7) and (8) were derived to obtain the shift amount W and the interval g, but three of the four luminous flux centers CI, C2, C3, and C4 Similarly, formulas corresponding to formulas (7) and (8) can be derived by using

That is, as above, the interval Dij (the interval between point i and point j)
When expressed using , the following combinations are applicable.

Among these combinations (I), (IV), (V)
.

In the case of (■), (U), (III), (Vl),
(1/I) Compared to the 1.2 embodiment, this embodiment has the advantage that the sensor width D12 or D34 may be shorter.

In this example, as in the first example, general formulas corresponding to formulas (1) to (+/I[I) are determined based on experimental data,
Using this formula, the positional deviation W and the distance g are determined.

(c) Fourth embodiment Two physical optical elements z1 provided on the first object plane. z3 and two physical optical elements z2 provided on the second object plane. z4
Instead of providing independent turns, each turn is constructed from one overlapping turn as shown in FIG. 5, and the same effect as described above is obtained.

In this embodiment, D corresponds to the distance between optical axes a1 and 82.
The value of is zero, and if D=0 in the first to third embodiments, this embodiment can be applied.

A feature of the pattern in this embodiment is that when the second object is tilted in the alignment direction, it is less affected than the pattern in FIG. 3.

That is, when using the pattern shown in FIG. 3, when the second object tilts, the first object tilts. The lens system of the second physical optical elements zl, z2 and the third.
Fourth physical optical element z3. Since the lens system of z4 is affected differently, a detection error occurs. In contrast, in this embodiment, the effects are the same, so even if a detection error occurs, the third
It has the advantage that it is extremely rare compared to the case shown in the figure.

(d) Fifth Embodiment In this embodiment, a plurality of combinations of two values between the diffracted light beams regarding both the deviation amount W and the interval g are detected, and the plurality of combinations are detected. The deviation amount W and the interval g obtained from the above are evaluated by an evaluation means to improve the detection accuracy. As an evaluation means at this time, for example, averaging a plurality of values of the deviation amount W and the interval g obtained from a plurality of combinations may be considered.

(Showing) Sixth Embodiment When actually implementing the first to fourth embodiments, pre-alignment is performed in advance. However, as is clear from Fig. 4, on the right and left sides of the deviation amount W=O, the positions of the luminous flux gravity centers C1 to C4 are reversed depending on the direction of deviation, but the states of the luminous flux at positions C1 to C4 are reversed. At first glance, it is not clear to which side the second object is shifted relative to the first object.

For this reason, in this embodiment, the first. Second two diffracted light beams u3.
fi'5 (7) Distance D12 between center of gravity positions C1 and C2 and the third. Fourth two diffracted light beams ff17. Each element is set so that the center of gravity position C3 of ff19 is different from the distance D34 between 04 and ff19.

This becomes clear by measuring the positions of the luminous flux gravity center positions C1 to C4 on the sensor 3 surface, and then calculating the differences between the positions C1 and C2 and between the positions C3 and C4.

Also, in the vicinity of the deviation amount W = O, the luminous fluxes overlap,
If the combinations of positions C1 and C2 and positions C3 and C4 are far apart, the state can be determined by determining the half-width of the luminous flux, for example.

In addition, in this embodiment, if the four light beams overlap on the sensor surface, it is only necessary to change the amount of deviation between the first object and the second object to make the discrimination possible, and then perform the discrimination.

(Effects of the Invention) According to the present invention, as described above, when the first object and the second object are arranged facing each other with a previously known distance g and positional deviation amount W, the position information Y from the detection means can be variously used. A general formula is obtained from this and recorded in a recording means. Then, when actually detecting the positions of both sides, by using the position information from the detection means and the general formula recorded in the recording means, it is possible to detect slight changes due to aberrations of the detection system and manufacturing errors. It is possible to eliminate the effects of error factors such as changes in the oscillation wavelength of the semiconductor laser due to the oscillation wavelength of the semiconductor laser, and to achieve a position pressure detection device that can detect the relative positions of both with high accuracy.

Further, according to the present invention, by determining the amount of positional deviation W between the first object and the second object and the distance g between the first object and the second object, there is no misidentification of the matching state, and highly accurate positioning is possible. It is possible to achieve a position detection device that can be matched and has a high throughput.

For example, position information CI, C in the position detection device of the present invention
3 and the deviation amount W, the above-mentioned constants are g = 30 μm, fl = 150 μm, L = 1
When 8627μm, yl=1544.75μm, the interval g
If there is an error of 0.06 μm, the amount of deviation W will be o, oo
An error of s μm occurs. Therefore, when trying to align with an accuracy of 0.01 μm, the error in the interval g is 0.06 μm.
It is necessary to keep it below about m. Therefore, in some way 0
．． The interval g must be set in advance with an accuracy of 0.6 μm or less.

On the other hand, according to the present invention, if the interval g is set with a certain degree of accuracy during pre-alignment, the amount of deviation W can be accurately determined regardless of the value of the interval g.

For example, in the method of determining the center of gravity of the two diffracted light beams by measuring the overlapping diffracted light beams whose centers of gravity are at positions C1 and C2, if the light intensity changes due to fluctuations in diffraction efficiency, the center of gravity will shift and cause errors. In the present invention, since the diffracted light beam is measured in a state where it is optically separated, the occurrence of such detection errors can be prevented.

Furthermore, in the present invention, the physical optical element is commonly used for detecting both the positional deviation amount W and the distance g, thereby reducing the luminous flux and the number of physical optical elements, simplifying the detection system and downsizing the entire device. We are trying to make this happen.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the main part of the first embodiment of the present invention, FIG. 2 is a schematic diagram of the main part when the optical path of each light beam in FIG. 1 is schematically developed, and FIGS. 3 and 5 are The first object 1 and the second object in Fig. 1
An explanatory diagram of the physical optical element provided on the surface of the object 2, Fig. 4. An explanatory diagram showing the positional relationship between the amount of deviation W and the light flux gravity center positions C1, C2, C3, and C4 on the sensor surface, Figs. 6 and 7 The figure is a schematic diagram of a conventional alignment device. In the figure, 1 is a first object, 2 is a second object, 3 is a sensor, 4 is a signal processing circuit, 5 is a control circuit, 6 is a stage controller, !1 ~f19 is a luminous flux, 21~z4 are physical optical elements,
al, C2 is the optical axis of the physical optical element, W is the amount of positional deviation, g
is the interval. Patent Applicant: Canon Co., Ltd. Figure 1 Figure 2 Figure 1 No. t<a Figure 3 Figure 5 Figure 6 Figure 7

Claims (1)

[Scope of Claims] (1) A physical optical element is provided on each of the first object plane and the second object plane, and the diffracted light beam of a predetermined order generated on a predetermined plane of the light beam incident on these physical optical elements is When detecting the relative positions of the first object and the second object by detecting position information with a detection means, a relative shift in the relative distance g between the first object and the second object is detected. With reference to a recording means that has experimentally determined and recorded the relationship between the amount W and the positional information y detected by the detection means, each of at least three diffracted light beams generated on a predetermined surface by the detection means The value between the diffracted light beams, which is related to both the relative shift amount W and the relative distance g between the first object and the second object, is at least 2.
1. A position detection device characterized in that a deviation amount W and an interval g are determined by a calculation means using an output signal from the detection means. (2) On the first object plane, there are first and third two
physical optical elements, second and fourth physical optical elements are disposed on the second object plane.
Two physical optical elements are provided, respectively, and the diffracted light beam generated on the predetermined surface is transmitted to one physical optical element on the first object surface and one physical optical element on the second object surface, respectively. 2. The position detection device according to claim 1, wherein the light beam is a diffracted light beam. (3) The two physical optical elements on the first object plane and the two physical optical elements on the second object plane each overlap each other to form one pattern. The position detection device described. (4) The first and second two planes generated on a predetermined surface via the first and second two physical optical elements.
The position of one diffracted light beam and the position of the third and fourth two diffracted light beams generated on a predetermined surface via the third and fourth two physical optical elements are detected at a distance of at least the width of the diffracted light beam, respectively. 3. The position detection device according to claim 2, wherein: (5) The detection means detects each of a plurality of combinations of two values between the diffracted light beams regarding both the deviation amount W and the interval g, and detects the deviation obtained from the plurality of combinations. 5. The position detection device according to claim 1, wherein the amount W and the distance g are evaluated by evaluation means. (6) The position detection device according to claim 5, wherein the evaluation means averages a plurality of values of the deviation amount W and the interval g obtained from a plurality of combinations. (7) Each element is set so that the positional distance D12 of the first and second two diffracted light beams on the predetermined surface and the positional distance D34 of the third and fourth two diffracted light beams on the predetermined surface are different. 5. The position detection device according to claim 4, wherein: