JPH042904A - Position detector - Google Patents

Abstract

PURPOSE:To accurately detect a positional deviation by so setting elements such as physical optical elements of two alignment marks as to cross them at predetermined angle when main light rays are projected on an article. CONSTITUTION:A luminous flux emitted from a light source for emitting a luminous flux of irregular light intensity distribution is enlarged to a predetermined beam diameter through a projecting optical system to become substantially parallel beam to be incident obliquely on alignment marks 5, 6 on an article 1. Then, the fluxes diffracted on the marks 5, 6 are, for example, converged at convex power by the mark 5, dispersed at concave power by the mark 6, and then introduced to alignment marks 3, 4 on the article 2. Thereafter, the fluxes which are dispersed by the mark 3 and converged by the mark 4 become signal lights, 7, 8 which are emitted from the article 2, passed through the article 1, and introduced to detectors 11, 12 to detect positional deviations. Here, in the steps of allowing the fluxes 7, 8 to arrive at the detectors 11, 12, the projecting locuses on the article of the optical paths are crossed to accurately detect the positional deviations.

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 devices, the present invention relates to a position detection device for detecting a position on a first object surface such as a mask or resicle (hereinafter referred to as “mask”). Suitable for determining the amount of relative positional deviation between the mask and wafer and aligning them when exposing and transferring a fine electronic circuit pattern formed on a wafer onto a second object surface such as a wafer. The present invention relates to a position detection device.

(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 position detection devices, so-called alignment marks for positioning are provided on the mask and the eight faces of the sea urchin, and position information obtained from these marks is used to perform alignment of both. As an alignment method at this time, for example, detecting the amount of deviation between both alignment marks by performing image processing, or using U.S. Patent No. 4037
No. 969, U.S. Patent No. 4,514,858, and JP-A-56-
As proposed in Japanese Patent No. 157033, a zone plate is used as an alignment mark, a light beam is irradiated onto the zone plate, and the position of a converging point on a predetermined plane of the light beam emitted from the zone plate is detected at this time. Is going.

In general, an alignment method using a zone plate has the advantage that compared to a method using a simple alignment mark, alignment can be performed with relatively high precision without being affected by defects in the alignment mark.

FIG. 11 is a schematic diagram of a conventional position detection device using zone play 1.

In the figure, a mask M is attached to a membrane 117, and is attached to a mask chuck 1 on an aligner body 115.
16. An alignment head 114 is arranged above the main body 115. In order to align the mask M and the wafer W, mask alignment marks 1 to MM and wafer alignment marks WM are printed on the mask M and the wafer W, respectively.

The light beam emitted from the light source 110 is turned into parallel light by the projection lens system 111, passes through the half mirror 112, and enters the mask alignment mark MM. The mask alignment mark MM is composed of a transmission type zone plate, and the incident light beam is diffracted, and the +1st-order diffracted light is subjected to a convex lens action to converge on a point Q.

Further, the wafer alignment mark WM has the function of a convex mirror (divergent function) that reflects and diffracts the light condensed to the point Q by the reflective zone plate and forms an image on the detection surface 119.

At this time, when the signal light flux that has undergone the 11th-order reflection and diffraction action at the wafer alignment mark WM passes through the mask alignment mark MM, it is transmitted as 0-order light without being subjected to lens action, and is condensed onto the detection surface 119. It is something that comes.

In the position detection device shown in the figure, when the wafer W is misaligned by a predetermined amount relative to the mask M, the incident position of the light beam incident on the detection surface 119 (the amount of light (center of gravity) shifts. There is a certain relationship between the displacement amount ΔδW on the detection surface 119 and the position displacement amount ΔσW at this time, and the displacement amount ΔδW on the detection surface 119 at this time
By detecting W, the relative positional deviation amount ΔσW between the mask M and the wafer W is detected.

(Problems to be Solved by the Invention) However, in the conventional position detecting device, the distance between two objects placed facing each other in order to perform alignment may vary from a preset value. In this case, along with this variation, the positional deviation detection magnification, which is the ratio ΔδW/ΔσW of the deviation amount ΔδW of the incident position of the light beam on the detection surface to the positional deviation amount ΔσW, also changes, resulting in a detection error of the positional deviation amount. There was a problem with the

In addition, the alignment head, which has a built-in light source, a light projecting optical system for guiding the light beam from the light source onto the mask surface, a light receiving system for receiving signal light, etc., is positioned relative to the alignment mark. When the fluctuation occurs, the incident position of the light beam onto the detection surface of the detection section also fluctuates, resulting in a problem in that a detection error of the positional deviation amount ΔδW occurs.

The present invention can be used even if there is a change in the distance between the first object and the second object to be aligned, which deviates from a preset value, or the position of the alignment head changes relative to the alignment mark. However, by appropriately setting each element such as the shape of the alignment mark provided on the first and second object planes and the angle of incidence of the emitted light beam onto the alignment mark, the relative position of the two objects can be determined. It is an object of the present invention to provide a position detection device that can accurately detect the amount of wear.

(Means for Solving the Problems) The position detection device of the present invention has a first object and a second object each provided with an alignment mark made of at least two physical optical elements, which are disposed facing each other, and which have an unrestricted light intensity distribution. A light beam from a light projecting means that emits a light beam is guided onto a predetermined surface after passing through each alignment mark provided on the first object and the second object, and the incident position of the light beam on the predetermined surface is determined. When detecting the amount of relative positional misalignment between the first object and the second object by detecting with the detection means, a sensor provided on the object surface of at least one of the first object and the second object. Each of the physical optical elements of the two alignment marks is arranged so that the optical paths of the principal rays of the two light beams emitted from the two alignment marks intersect each other at a predetermined angle when the principal rays are projected onto the object surface. It is characterized by setting elements.

That is, the present invention provides alignment marks for first and second signals that function as physical optical elements on the object plane A when the object plane A and the object plane B are a first object and a second object to be aligned. A1 and A2 are formed, and alignment marks B1 and B2 for first and second signals having a function as a physical optical element are also formed on the object plane B, and a light beam is made to enter the alignment mark A1. The diffracted light generated at this time is made incident on the alignment mark B1, and the center of gravity of the light beam within the plane of incidence of the diffracted light from the alignment mark B1 is detected by the first detection section as the incident position of the first signal light beam.

Here, the center of gravity of the light beam is the point in the cross section of the light beam where the integral value becomes 0 vector when the product of the position vector of each point of the cross section circle from that point multiplied by the light intensity of that point is integrated over the entire cross section. However, for convenience, the point at which the light intensity is at its peak may be used as the center of gravity of the light flux. Similarly, a light beam is made incident on the alignment mark A2, and the diffracted light generated at this time is made incident on the alignment mark B2, and the center of gravity of the light beam on the incident surface of the diffracted light from the alignment mark B2 is set as the incident position of the second signal light beam and sent to the second detection section. Detect. Then, the object plane A and the object plane B are positioned using the two position information from the first and second detection sections. At this time, each element is set so that when the optical paths of the two light beams emitted from the two alignment marks on at least one object surface are projected onto the object surface, their trajectories intersect each other at a predetermined angle. ing.

In this Ikemizu invention, the center of gravity of the light beam incident on the first detection section and the center of gravity of the light flux incident on the second detection section are displaced in opposite directions with respect to the positional misalignment of object plane A and object plane B. Alignment mark AI, A2. B1. B2 is set.

(Example) Fig. 1 is an explanatory diagram showing the principles and constituent elements of the present invention developed, and Fig. 2 is a perspective view of main parts of the first embodiment of the present invention based on the configuration of Fig. 1. .

In the figure, 1 is the first object corresponding to object plane A, and 2 is object plane B.
The second object corresponds to , and the case where the amount of relative positional deviation between the first object 1 and the second object 2 is detected is shown.

In FIG. 1, two first objects 1 are shown because the light that passes through the first object 1 and is reflected by the second object 2 passes through the first object 1 again. 5 is an alignment mark provided on the first object 1, and 3 is an alignment mark provided on the second object 2, for obtaining the first signal. Similarly, 6 is an alignment mark provided on the first object 1, and 4 is an alignment mark provided on the second object 2, for obtaining the second signal light.

Each alignment mark 3, 4, 5.6 has the function of a physical optical element with or without a one-dimensional or two-dimensional lens effect. 9 is the wafer scribe line,
10 is a mask scribe line. 7 and 8 are the first and second alignments described above. A second signal beam is shown. Reference numerals 11 and 12 indicate first and second detection units for detecting the first and second signal beams, respectively. from the second object 2 to the first
Alternatively, the optical distance to the second detection unit 11.12 will be used for convenience of explanation. Let g be the distance between object 1 and second object 2, and let f'al+ be the focal length of alignment marks 5 and 6, respectively.
Let f a2 be the amount of relative positional deviation between the first object 1 and the second object 2, and let Δσ be the amount of relative positional deviation between the first object 1 and the second object 2, and then the 1° second detection unit 11.1
Let S, S2 be the displacement amounts of the first and second signal beam centers of 2 from the coincident state, respectively. The alignment light flux incident on the first object 1 is assumed to be a two-plane wave for convenience, and the symbols are as shown in the figure.

The displacement amounts S1 and S2 of the center of gravity of the signal beam are the focal points F, , F2 of the alignment marks 5 and 6 and the alignment mark 3,
A straight line Ll connecting the optical axis centers of No. 4.

It is determined geometrically as the intersection between L2 and the light receiving surfaces of the detection units 11 and 12. Therefore, with respect to the relative positional deviation between the first object l and the second object 2, the displacement amount S,,
2 in opposite directions to each other, align the alignment marks 3 and 4.
This is achieved by making the signs of the optical imaging magnifications opposite to each other.

Next, the 1st column for alignment shown in FIGS. 1 and 2. Second
The optical path of the chief ray of the signal beam 7.8 will be explained.

In the following explanation, the principal ray refers to a ray passing through the axis of the alignment mark when the alignment mark has an imaging effect, and refers to the central ray of the effective beam diameter when the alignment mark does not have an imaging effect.

A light beam emitted from a light source (not shown) that emits a light beam with a non-uniform light intensity distribution is expanded to a predetermined beam diameter through a projection optical system (not shown), and becomes a substantially parallel beam, which is then aligned with the alignment mark on the first object 1. 5.6 is incident obliquely to the normal to the object surface. The light intensity distribution of the substantially parallel light beam reaching the first object 1 and 2 is generally an unrestricted Gaussian distribution.

The alignment mark according to the present invention consists of two regions in which the center-to-center distance is a predetermined value other than zero, and is formed on each object surface to be aligned. As described above, the alignment light beam enters the alignment mark 5.6 on the first object plane as a single Gaussian beam. For example, the light beam diffracted by the alignment marks 5 and 6 on the first surface of the first object receives a converging effect of convex power at the alignment mark 5, and a diverging effect of concave power at the alignment mark 6.
After that, the alignment marks 3 and 4 on the second object plane are reached.

Further, the light beams which are subjected to the diverging effect of the concave power at the alignment mark 3 on the second object surface and the convergence effect of the convex power at the alignment mark 4 become 1° second signal beams 7 and 8, respectively, and exit the second object surface 2. After passing through the surface of the first object, the light enters a detection unit 11.12 located at a predetermined position. In this embodiment, the amount of positional deviation in the illustrated X direction is detected, and the detection units 11 and 12 use one-dimensional sensors that measure the light intensity distribution in the X direction.

In this embodiment, the first. Second signal beam 7
, 8, after emitting the second object surface 2, the second object surface (
The alignment marks and the incident angle of the projected light flux are configured so that the projection trajectories on the first object plane (or the first object plane) always intersect. Hereinafter, such an optical path configuration will be referred to as a "crossing optical path."

As a result of a simulation based on optical path tracing, the present inventor found that by adopting a crossed optical path, when the above-mentioned alignment mark system is irradiated with an alignment light beam having a Gaussian-like light intensity distribution, the first object 1 It has been found that the occurrence of positional deviation detection errors caused by variations in the distance between the second object 2 and the second object 2 can be extremely effectively suppressed.

That is, in this embodiment, even if the amount of relative positional deviation between the first object and the second object remains unchanged, the detection unit 11, 12
By adopting the above-mentioned crossed optical paths, the error in detecting the amount of positional deviation due to the variation in the distance between the incident positions of the two alignment signal beams (isometrically, the light intensity gravity center position) in 1 can be suppressed well. That's what I do.

Furthermore, the inventor has found that the occurrence of positional deviation amount detection errors caused by fluctuations in the irradiation center position of the alignment light beam on the first object surface can also be effectively suppressed by the crossed optical paths.

The present invention suppresses the occurrence of the above-mentioned misalignment detection error by setting each element so that such crossed optical paths are formed, and increases the accuracy of the relative misalignment between the first object and the second object. This enables accurate detection.

FIG. 3(A) shows a configuration diagram of the peripheral portion of the apparatus when the first embodiment shown in FIG. 2 is applied to a proximity type semiconductor manufacturing apparatus. Elements not shown in FIG. 2 include a light source 13, a collimator lens system (or beam diameter conversion lens) 14, a projection light beam bending mirror 15, a pickup housing (alignment head housing) 16. Wafer stage 1
7, a positional deviation signal processing section 18, a wafer stage drive control section 19, etc. E indicates the exposure beam width.

Also in this embodiment, detection of the amount of relative positional deviation between the mask 1 as the first object and the wafer 2 as the second object is performed in the same manner as described in the first embodiment.

In this example, the procedure for alignment is as follows:
For example, the following method can be adopted.

The first method is to use the detection surface 11a of the detection unit 11.12 for the amount of positional deviation Δσ between the two objects.

12b" - is obtained, the signal processing unit 18 calculates the positional deviation amount Δσ between both objects from the gravity center deviation signal, and the stage is moved by an amount corresponding to the positional deviation amount Δσ at that time. The drive control unit 19 moves the wafer steak chef.

The second method is to use the signal processing unit 18 to determine the direction in which the positional deviation amount Δσ is canceled from the signals from the detection units 11 and 12.
The stage drive control unit 19 moves the wafer stage 1 in that direction.
7 and turn the edges until the positional deviation amount Δσ falls within the allowable range.

Flowcharts of the following alignment procedure are shown in FIGS. 3(B) and 3(C), respectively.

In this embodiment, as can be seen from FIG. 3(A), the light beam from the light source 13 is directed toward the alignment mark 5,
6 and exits from the alignment mark 3.4 to the outside of the exposure light beam, which is received by a detection unit 11.12 provided outside the exposure light beam, thereby detecting the position of the incident light beam.

With such a configuration, it is possible to realize a system in which the pickup housing 16 does not require a retracting operation during exposure.

Next, details of the configuration of each part of the first embodiment will be explained with reference to FIGS. 2, 3(A), and 4.

Figure 4 is 1. FIG. 4 is an explanatory diagram of the incident state of the second signal light beams 7 and 8 to the 1° second detection section 11.12. The alignment light beam emitted from the semiconductor laser (center wavelength 0.785 μm), which is the light source 13 in the pickup housing 16 for alignment, passes through a projection optical system consisting of a collimator lens system 14 and a beam splitter (or half mirror) 15. The light becomes a parallel light beam and obliquely enters the mask surface at an angle of 17.5° in the yz plane with respect to the mask surface normal.

Light intensity distribution of alignment light flux on one mask surface (1(x
,y)) is a Gaussian distribution, and if we take the coordinate system as shown in the figure, aX = 680 μm, σ, ==120 μm
becomes. Furthermore, the amount of positional deviation is detected in the X direction.

The sizes of the two alignment marks on the mask and the eight faces of the sea urchin are both 90 μm in the X direction and 50 μm in the X direction.
m and are arranged adjacent to each other as shown in FIG.

The alignment mark 5 on the first surface of the mask is a convex power crating lens that has a light flux convergence effect, the focal length corresponding to the +1st order diffracted light is 214723 μm, and the deflection angle in the yz plane of the principal ray of the +1st order transmitted diffraction light is The direction of the principal ray exiting one surface of the mask at 17.5 degrees is parallel to the normal to the mask surface.

In addition, the alignment mark 6 on the first surface of the mask is a concave power crating lens that has a light beam diverging effect, and has a +
The focal length corresponding to the first-order diffracted light is 158.455 μm,
Similar to the alignment mark 5, the deflection angle of the chief ray is 17.5° in the yz plane.

In both alignment marks 5 and 6, the polarization angle is 0° in the XZ plane, and the principal ray direction does not change.

In this example, the angle of oblique incidence α of the light beam on one surface of the mask is 10°〈　α　〈80゜ It is desirable to set it within the range of .

At the alignment mark 3 on the two surfaces of the wafer, only the light beam that has been diffracted and transmitted in the +1st order is incident on the alignment mark 5 on the mask surface. Here, the first signal light beam 7 that is further diffracted and reflected in the +1st order is subjected to a diverging effect. The alignment mark 3 is a grating lens with concave power, and its focal length is -182,912 μm. In the xz plane, the principal ray direction forms an angle of 3° with respect to the normal to the wafer surface, and then As shown in FIG. 4, the beam reaches the detection unit 12 while maintaining this angle.

Similarly, the alignment mark 4 on the wafer 1 is a cretin lens (focal length lit 190.378 μm) with convex power corresponding to the +1st-order reflected diffraction light, and the light beam 8 transmitted and diffracted by the alignment mark 6 on the mask 1 It has an optical effect on the

Further, as shown in FIG. 4, the second signal beam 8 emitted from the alignment mark 4 is reflected so that its principal ray direction forms an angle of 3.35° in the xz plane with respect to the normal to the wafer 2 surface. After being emitted, the light passes through the mask surface at the zeroth order while maintaining the angle, and reaches the detection unit 12.

On the other hand, the first one when ejecting from the second side of the wafer. Second signal beam 7
, 8 in the xz plane are 7° and 13°, respectively, with respect to the normal to the wafer surface.
Elements such as the alignment mark shape and the optical system are set so that the light enters two detection units 11 and 12.

Note that the detection units 11 and 12 do not need to be arranged on the same plane as shown in FIG. It may also be installed.

Now, the mask 1 and the wafer 2 are misaligned by Δσ in the direction parallel to the positional deviation detection direction (X direction), and the mask 1 and the wafer 2 are
The focal point 01 of the luminous flux reflected by the grating lens 3
Let b be the distance to F1, and a be the distance to the condensing point F1 of the light beam that has passed through the grating lens 5 of the mask 1, then the shift amount Δδ of the center of gravity of the condensing point on the detection unit 11 is Δδ=Δσ× (-10 1) ・・・・・・・・・
(a), that is, the center of gravity shift amount Δδ is (b / a +
1) Expanded twice. For example, a = 0, 5
mm, b = 50 mm, the center of gravity shift amount Δδ is expanded by a factor of 101 from equation (a).

In this embodiment, the concave power and the convex power are determined depending on whether minus order diffracted light or positive order diffracted light is used.

The diameter of the grating lenses 3 and 4 on the evaporator 2 is 180 μm, and the diameter of the grating lenses 5 on the mask 1 is 180 μm.
The umbrella diameter of 6 is set to 180 μm, and the positional misalignment (axis misalignment) between the mask and the sea urchin is magnified by 100 times, causing the center of gravity of the light beam to shift on the detection unit 11.12.
The diameter of the luminous flux on 2 (Airy disk e-2 diameter) is 200μ
The arrangement and focal length of each element were determined so that the distance was about m.

In addition, the center of gravity shift amount Δδ and position shift amount Δσ at this time are (a
) As is clear from the equation, there is a proportional relationship. Detection unit 11
．． If the resolution of 12 is 0.1 μm, the positional deviation amount Δσ has a position resolution of 0.001 μm.

In this embodiment, the focal length of each alignment mark between the mask and the wafer is set as described above, the distance between the mask and the sea urchin is 30°0 μm, and the center position of the detection unit 1211 is set (0, 0, -4, 203,18,204)(0,0
, -2,277,18,543) (unit: mm), the 1st. Detection sensitivity of the second signal light 7.8 on the detection unit 11.12 surface (i.e., the amount of variation in the light beam incident position on the detection unit surface with respect to the variation in relative positional deviation between the mask and the wafer (X direction)) ratio) became 100 and +100, respectively.

Next, the pattern shapes of grating lenses 5 and 6 for masks and grating lenses 3 and 4 for wafers in this embodiment will be explained.

First, the mask grating lens 5.6 is set so that a parallel beam of a predetermined beam diameter enters at a predetermined angle and is focused at a predetermined position.

Generally, the pattern of a grating lens is an interference fringe pattern on the lens surface when a coherent light source is placed at each of the light source (object point) and image point.

Here, the origin is located at the center of the scribe line width, with the X axis in the scribe line direction, the Y axis in the width direction, and the Z axis in the normal direction of the mask surface. α in the yz plane with respect to the normal to the mask surface
A parallel beam of light, whose projected component is perpendicular to the scribe line direction, is incident at an angle of The equation of the ink lens curve group is expressed as ysin a P, (x, y) - P2 = m, where x and y represent the contour position of the grating.
^/ It is given by 2-(]). Here, ^ is the center wavelength of the wavelength range in which the alignment light beam is used, and m is an integer.

Assuming that the principal ray is incident at an angle α, passes through the origin on the mask surface, and reaches the focal point (Xl, Y+, Zl), the right side of equation (1) has a wavelength relative to the principal ray depending on the value of m. m / 2 times indicates that the optical path length is long (short), and the left side is the optical path of the principal ray that passes through the point (x, y, 0) on the mask and reaches the point (Xl + y+ + Zl ). Represents the difference in optical path length.

On the other hand, grating lenses 3 and 4 on the wafer are set so as to focus the spherical waves emitted from a predetermined point light source onto a predetermined position (on the detection surface). Letting the position of the point light source be g, which is the gap between the mask and the sea urchin, (Xl, y+,
Zl g). Assuming that the mask and wafer are aligned in the X-axis direction, and that the alignment light beam is focused on the point (X2.y2.Z2) on the detection surface when alignment is completed, the grating lens on the wafer will be The equation of the curve group is expressed as +mλ/2 (2) in the coordinate system defined above.

Equation (2) shows that the surface of the sea urchin is at z=-g, the principal ray is the origin on the eight surface of the sea urchin, a point on the mask surface (0, Og), and a point on the detection surface (X2.y2.Z2). This is an equation that satisfies the condition that the difference in optical path length between the ray passing through the grating (x, y, -g) on the mask surface and the principal ray is an integral multiple of a half wavelength.

In general, a zone plate (grating lens) for a mask has two regions formed alternately: a region through which light rays pass (transparent section) and a region through which light rays do not pass (light shielding section).
1 amplitude type grating element. Further, a zone plate for a wafer is made, for example, as a phase grating pattern with a rectangular cross section. In equations (1) and (2), the outline of the grating is defined at a position that is an integer multiple of a half wavelength with respect to the principal ray, which means that in the grating lens 5 or 6 on the mask, the line width of the transparent part and the light-shielding part is This means that the ratio of the lines and spaces of the rectangular grating of the grating lens 3 or 4 on the wafer is 1:1.

The grating lenses 5 and 6 on the mask "2" are formed by transferring the grating lens pattern of the reticle previously formed by EB exposure onto the organic thin film "2" made of polyimide, or the grating lenses on the wafer are formed on the mask. It is formed by forming an exposure pattern on a wafer and then performing exposure transfer.

FIG. 10(A) shows the grating lens 5 on the mask surface.
, 6. Figure (B) shows a pattern of an embodiment of the grating lenses 3 and 4 on the eight faces of the sea urchin.

With the configuration explained above, the cap between the mask and the sea urchin (
1. due to the change in distance (interval) and the change in position (parallel movement) of the pickup housing 16. The magnitude of the variation in the interval between the light quantity gravity center positions (hereinafter referred to as spot interval) measured along the X direction of the second signal light beam was measured. As a result, when using the crossed optical path method according to the present invention described above, the gap variation is ±3.0 μm.
In contrast, the variation in spot spacing was 1.9 μm, and the relative positional deviation detection error between the mask and the sea urchin was 0.0095 μm.
It became m.

On the other hand, in the conventional optical path system (FIG. 11; positional deviation detection sensitivity is the same), the amount of variation in the spot interval was 12.56 μm, and the positional deviation detection error was 0.063 μm. That is, if the crossed optical path method according to the present invention is used, the detection error is approximately 6
Reduce to 1/0.

On the other hand, with respect to positional fluctuations of the pickup housing 16 (translation in parallel to the
μm), which is about half that of the conventional one.

FIG. 5 is a schematic diagram of the optical path of the second embodiment of the present invention, and FIG.
It is shown in the same way as the optical path in the figure. In the figure, the positional deviation detection direction is the X direction.

The main feature of this embodiment is that a crossed optical path is realized by the imaging effect of the two alignment marks 5a and 6a on one surface of the mask, and the alignment marks 3a and 4a on the two surfaces of the wafer are The reason is that it does not have a deflecting effect on the chief ray of the signal light. The main features such as the focal length, size, and arrangement of each alignment mark and the configuration of the optical system are the same as in the first embodiment.

FIG. 6 is a perspective view of essential parts of a third embodiment of the present invention.

In this embodiment, the first and second signal beams 7.8 for alignment are configured to be received by a single light receiving section 611 consisting of one light receiving area, and two incident beam positions are set on the surface of the light receiving section. The amount of misalignment between the mask and the sea urchin is detected by detecting the spot interval between them.

The crossed optical paths are realized by the imaging effect of the alignment marks 3.4 on the first surface of the wafer. The arrangement of the angular alignment mark in the xz plane when the principal ray of the second signal beam exits from the wafer surface (or mask surface) and the configuration of the optical system (especially the Gaussian beam diameter) are the same as in the first embodiment. It is. However, there are two signal beams 7 on the surface of the light receiving section 611.
The grating pattern shape of each alignment mark is designed so that the final exit angle of both beams in the xz plane is 13° with respect to the normal to the first mask surface (or the second wafer surface) in order to make the incident angle 8°. ing.

FIG. 7 is a perspective view of essential parts of a fourth embodiment of the present invention.

In this embodiment, alignment mark areas for the first and second signal beams 7 and 8 for alignment are arranged at a predetermined distance, for example, 100 μm, on the mask 1 and wafer 2 surfaces.

Here, assuming that the diameter of the Gaussian beam projected onto the alignment mark 5°6 on the mask 1 side is the same as in the first embodiment, the final exit angle of the 1st and 2nd signal beams in the crossed optical path is the optimal value. Positional deviation measurement errors due to smoothing, gap fluctuations, and fluctuations in the position of the alignment head housing increase.

Therefore, in this embodiment, the Gaussian beam diameter is the same as in the first embodiment, and the first. The final exit angles of the second signal beam in the xz plane are +4.0° and −4.8°, respectively.

FIGS. 10A and 10B show examples of patterns of alignment marks on the mask and the eight faces of the sea urchin, respectively, in this embodiment.

In this way, the optimum conditions for setting the crossed optical paths are determined by various factors such as the diameter of the Gaussian projected beam, the size and arrangement of the alignment mark, and the focal length. In this embodiment, the optimum value is obtained through simulation using a large number of ray tracings, and each element is configured based on this.

FIG. 8 is a perspective view of essential parts of a fifth embodiment of the present invention.

In this embodiment, the first . second signal beam 7,
As shown in the figure, the alignment mark areas for No. 8 are arranged adjacently so that some of them overlap.

FIGS. 10(G) and 10(D) show an embodiment showing patterns of alignment marks 5, 6 on the first side of the mask and alignment marks 3, 4 on the second side of the wafer.

Area 80 in Figures 8 and 10 (C) and (D)
1° 802 is an area where alignment marks overlap with each other.

In this embodiment, the Gaussian beam diameter of the light beam is the same as in the first embodiment, and the first. The final exit angles of the second signal beams 7 and 8 in the xz plane were each +2.502.8°. In addition, the distance between the alignment mark centers on each surface is 60 μm, and
Overlapping area of direction alignment marks (801, 80
2) is 30 μm.

FIG. 9 is a schematic diagram of a main part of a sixth embodiment showing a position detection part in which the present invention is applied to a reduction projection exposure apparatus.

In the figure, a light beam emitted from a light source 13 is converted into parallel light by a projection lens system 14 and irradiated onto reticle alignment marks 3L1 and 3L2 on a reticle L surface as a first object. At this time, reticle alignment marks 3L1, 3L
2 is the point Q for each passing light. , Qo'.

And point Q. , Qo' is reduced by a lens system 18
The distance aw, aw' from the wafer W as the second object is
The light is focused on points Q and Q' that are far apart.

In the figure, 7 and 8 are alignment marks 3L1 and 3, respectively.
The first . caused by L2. 907, indicating a second signal light flux;
908 is each chief ray.

Wafer alignment marks 4wl, 4w are on the wafer W.
2 are provided, and this wafer alignment mark 4
wl and 4w2 constitute reflective physical optical elements, and when light beams 7 and 8 converge on points Q and Q', respectively, are incident,
The light flux is reflected and passed through the half mirror 19 to the detection unit 1.
It has the function of a concave mirror that forms an image on one surface.

Similar to the first embodiment, the intersecting optical paths are set by the action of the alignment marks 4w1 and 4w2 on the wafer surface, and the intersecting angle is the same as in the first embodiment. The first . As for the second signal beam, only chief rays 907 and 908 are shown as representatives in FIG.

(Effects of the Invention) According to the present invention, the first . Two wavefront conversion elements (physical optical elements) each having an imaging function (optical function) are formed as alignment marks on the second object plane,
The imaging effect of the alignment mark is sequentially applied to each object plane (
For example, the first. a second object or a second object; (order of first object plane, etc.)
The first of the two I received. When detecting the amount of positional deviation based on information on the incident position of the second signal beam on a predetermined plane, each element is set so that the cross-sectional circular projection components including the positional deviation detection direction of the optical paths of the two signal beams intersect. Accordingly, it is possible to achieve a position detection device capable of detecting the amount of positional deviation with high precision, which is extremely resistant to the influence of changes in the distance between two objects to be aligned and changes in the position of the projected light beam from the light source.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the principle and structural requirements of the present invention, FIG. 2 is a perspective view of the main part of the first embodiment of the present invention based on the configuration of FIG. 1, and FIG. Schematic diagrams 1 and 3 of main parts in which the first embodiment shown in the figure is applied to a proximity type semiconductor manufacturing device.
Figures (B) and (C) are flowcharts of the measurement control in Figure 3 (A), Figure 4 is a cross-sectional diagram of the optical path of the first embodiment in Figure 2, and Figure 5 is a second embodiment of the present invention. Optical path cross-sectional explanatory diagram, No. 6
9 to 9 are perspective views of main parts of the third to sixth embodiments of the present invention, FIGS. 10(A) to 10(D) are explanatory diagrams of the arrangement of alignment marks according to the present invention, and FIG. 11 is a conventional FIG. 2 is a schematic diagram of main parts of the position detection device of FIG. In the figure, 1 is the first object (mask), 2 is the second object (wafer), 3, 4, and 5.6 are alignment marks, and 7.8
are the first. 2nd signal beam, 9 wafer scribe line, 10 mask scribe line, 11.12 detection unit, 13 light source, 14 collimator lens system, 15 half mirror, 116 alignment head housing, 18 signal processing 19 is a wafer stage drive control section. Figure (B) (C)

Claims (3)

[Claims] (1) A first object and a second object, each provided with an alignment mark made of at least two physical optical elements, are placed facing each other, and a light beam from a light projecting means that emits a light beam with a non-uniform light intensity distribution is directed to the target object. By guiding the light onto a predetermined surface after passing through each alignment mark provided on the first object and the second object, and detecting the incident position of the light beam on the predetermined surface by a detection means, When detecting the amount of positional deviation relative to a second object, the principal rays of two light beams emitted from two alignment marks provided on the object surface of at least one of the first object and the second object are detected. A position detection device characterized in that each element such as a physical optical element of the two alignment marks is set so that the optical path intersects each other at a predetermined angle when the principal ray is projected onto the object surface. (2) The position detection device according to claim 1, wherein the non-uniform light intensity distribution is a Gaussian distribution. (3) The position detection device according to claim 1, wherein the two alignment marks provided on the first object and the two alignment marks provided on the second object have an imaging function.