JP2002359186A - Projection aligner and position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a projection aligner having high position detecting accuracy and a position detector in which offset between processes is suppressed. SOLUTION: The projection aligner comprises a photoelectric conversion element, and a position detecting optical system for illuminating an object to be detected with light from a light source and focusing reflected light from the object onto the photoelectric conversion element wherein the position of the object is detected based on an image signal detected by the photoelectric conversion element and a wafer is aligned by the detected position of the objected. The position detecting optical system has aberration and the center of gravity of light intensity distribution on the pupil face of the position detecting optical system illuminating the object is set to cancel asymmetry due to aberration of the image signal of the object.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus and a position detecting apparatus, and more particularly, to a semiconductor IC and an LS.
In manufacturing the I, when projecting a pattern on a reticle surface onto a wafer, position information of an object such as a reticle or a wafer is detected with high accuracy by observing an image of the object, and the detected position information is This is suitable for performing the positioning of the object based on the information.

[0002]

2. Description of the Related Art In recent years, the progress of semiconductor device manufacturing technology has been increasing at an ever-increasing rate, and accordingly, there has been a remarkable progress in fine processing technology. In particular, optical processing technology using a projection exposure apparatus that projects a pattern on a reticle surface, which forms the center of the reticle surface, onto a wafer extends to a submicron region with a boundary of 1 MDRAM.

As a means for improving the resolving power of a projected pattern image, a method of increasing the NA of a projection optical system by fixing the wavelength of exposure light to a method that has been used in the past for a projection exposure apparatus, and an exposure wavelength. There is a method of shortening the wavelength from the g-line to the i-line and further to the oscillation wavelength of the excimer laser. Recently, attempts have been made to expand the limit of optical processing by light exposure using a phase shift mask, modified illumination, or the like.

[0004] On the other hand, with the improvement of the resolving power, the alignment for relatively aligning the wafer and the reticle in the projection exposure apparatus also needs to be improved in accuracy. A projection exposure apparatus for manufacturing a semiconductor element needs to function not only as an exposure apparatus but also as a position detection apparatus.

FIG. 3 shows a configuration of a position detecting system for alignment in a conventional projection exposure apparatus for manufacturing a semiconductor element. Although the x and y axes are taken in the surface of the wafer 4 as shown in the figure, the x and y directions are the same in the position detection system of the projection exposure apparatus, so the measurement in the y direction will be described here. Here, the position detection optical system (position detection system) is a generic name for all the optical systems from the light source to the detection.

Light emitted from a light source (not shown) such as a He-Ne laser is transmitted through a fiber 12 to an illumination optical system 11.
It is led to. The light is reflected by the polarizing beam splitter 10 into an S-polarized light component perpendicular to the plane of the paper, passes through the λ / 4 plate 7, and is converted into circularly polarized light. Thereafter, the light is applied to the imaging optics 6, 5,
Via a mirror 30 and a projection exposure optical system 1, a mark (alignment mark) 31 formed on a wafer 4 placed on a stage 2 which can be driven in the xyz directions is subjected to color illumination. The reflected light or scattered light from the mark 31 passes through the projection exposure optical system 1, the mirror 30, and the imaging optical systems 5 and 6 again, passes through the λ / 4 plate 7, and then becomes P, which is an in-plane component.
Converted to polarized light. Since the light is converted into P-polarized light, the light passes through the polarizing beam splitter 10 and forms an image of the mark 31 on the photoelectric conversion element 9 such as a CCD camera by the imaging lens 8. The signal of the mark image detected by the photoelectric conversion element 9 is subjected to image processing, the position of the mark 31 is detected with high accuracy, and the stage 2 is driven from the detected value to align the wafer 4. ing.

[0007]

The conventional position detection system shown in FIG. 3 has several problems that lower the position detection accuracy.

First, there is a problem associated with the detection wavelength. In such a position detection system, non-exposure light is used as a light source for alignment in order to prevent exposure when detecting a mark image. In the projection exposure optical system 1, various aberrations are optimized with respect to the exposure wavelength, so that aberrations occur at the wavelength of the non-exposure light, and there are factors that cause measurement errors during position detection due to the influence of manufacturing errors. Become.

[0009] The second factor is a problem with color illumination. It is practically difficult to use illumination at σ = 0 in the illumination method because of the problems of light quantity and spatial frequency cutoff at the time of image formation. Generally, a light source having a light emitting surface of finite size is used. Used. For example, in practice, light from a laser light source is guided to an illumination system through a fiber, or a lamp itself is used as a light source.

Since σ is not zero, illumination light having a certain angle with respect to the optical axis exists on the wafer surface of the position detection surface.
Kerr illumination is a method of illuminating the detection surface uniformly.
It does not guarantee the uniformity of the effective light source, which is the distribution of the pupil plane of the detection optical system. Therefore, when the light intensity distribution on the effective light emitting surface is not symmetric with respect to the measurement direction of the mark, that is, when the incident angle distribution of the illumination light with respect to the detection surface is asymmetric, the light intensity distribution of the observed mark image is symmetrically illuminated. Unlike the above-described method, a problem of causing a measurement error occurs.

FIG. 4A is a bird's-eye view of the measurement mark 31 in the y direction, FIG. 4B is a cross-sectional view of the mark seen from the x direction,
FIG. 4C shows an observed signal waveform.

Since the light intensity distribution on the effective light emitting surface is equivalent to the light intensity distribution of the light source, an intensity distribution of the incident angle on the detection surface depends on the intensity of the light emitting region. In FIG. 4, 32a is marked.
Light incident perpendicularly to the mark 31, and 32b and 32c are incident light from directions different in direction but at the same angle to the vertical direction, and the mark 31 having the step structure is illuminated to detect the position. Consider a case where Assuming that the illumination light intensity of the light 32b incident from the oblique direction is lower than the illumination light intensity of the light 32c incident from the oblique direction as shown in the figure, when the mark 31 is detected, the scattered light at the mark edge portion is detected. There arises a problem that a difference occurs in the intensity and accurate position detection cannot be performed. Assuming that the cross-sectional shape of the mark 31 is perfectly symmetric for simplicity, it is not necessary to consider the difference in the interference condition of the scattered light from the mark edge. If the intensity is higher than that of the light 32b, the state of light scattering at the mark edge differs, and the resulting image signal of the mark becomes asymmetric as shown in FIG. 4 (c). That is, although the mark itself is symmetric,
If the illumination condition is asymmetric, the waveform of the image signal to be detected is distorted, and it is difficult to accurately detect the mark position. Of course,
If the intensities of the light 32b and the light 32c are equal, the waveform has a completely symmetric shape due to the symmetry.

The actual asymmetry of the signal also occurs due to the difference in the structure of the mark step and the difference in the manufacturing process of a semiconductor such as a resist. In addition, the scattering characteristics of the edges are invariably proportional to and inversely proportional to the intensity of the incident light, which complicates the generation of signal asymmetry. However, it is important for the apparatus itself to remove the measurement error of the mark due to the asymmetry of the incident angle intensity of the illumination light in the measurement direction.

As a method for solving such a phenomenon, a filter such as a diffusion plate is arranged on a pupil plane or an image plane of the position detection system,
The light intensity distribution and the angle distribution are made uniform. However, when the diffusion plate is used, the amount of light on the object surface is reduced in inverse proportion to the uniformity of the light intensity, and it may be difficult to detect the alignment mark depending on the semiconductor element manufacturing process. The present invention, taking into account the above points and the facts found through some experiments, optimizes the illumination conditions of the position detecting optical system to eliminate various aberrations of the position detecting optical system including the projection exposure optical system, It is an object of the present invention to provide a projection exposure apparatus and a position detection apparatus suitable for manufacturing a highly integrated semiconductor element by improving detection accuracy.

[0015]

As described above, the one-dimensional or two-dimensional light intensity distribution of the Fourier transform plane of the image plane corresponding to the pupil plane of the position detecting optical system of the position detecting device is determined by the object to be detected. Corresponds to the angular characteristics of the light that illuminates the mark. And a mark to be detected based on the angle characteristic.
The image signal of the clock is affected. When the position detection optical system including the projection exposure optical system has no aberration with respect to the detection light, in order to make the detected image signal symmetric, the angle characteristic of the illumination light is symmetric with respect to the center of the mark. What is necessary is just to become. That is, it is necessary to make the light intensity distribution on the pupil plane symmetrical with respect to the optical axis. The symmetry required for the pupil plane intensity here relates to the measurement direction of the mark.

Further, according to the experiment of the inventor, it has been confirmed that the detected image signal of the mark changes remarkably depending on the position of the center of gravity of the light intensity distribution. If the position detecting optical system including the projection exposure optical system itself has aberrations, the asymmetry of the image signal of the mark due to these effects can be canceled by adjusting the optical center of gravity of the pupil plane. It has also been confirmed by the inventor that the signal has a sensitive mark. The present invention has been made in consideration of the above points, the position detection optical system is configured with an illumination system capable of adjusting the optical center of gravity, by optimizing the illumination conditions by observing a specific image signal, It is characterized by improving the position detection accuracy of the mark.

Next, the structure of the invention of each claim will be specifically described.

A projection exposure apparatus according to a first aspect of the present invention illuminates a test object with light from a photoelectric conversion element and a light source, and detects a position at which reflected light from the test object forms an image on the photoelectric conversion element. A projection exposure apparatus that has an optical system, detects a position of the test object based on an image signal detected by the photoelectric conversion element, and aligns a wafer based on the detected position of the test object. The position detection optical system has an aberration, and the position of the light illuminating the object to be measured is such that the image signal of the object to be tested acts in a direction to cancel the asymmetry due to the aberration. The center of gravity of the light intensity distribution on the pupil plane of the detection optical system is set.

According to a second aspect of the present invention, in the first aspect of the present invention, the position of the center of gravity of the light intensity distribution on the pupil plane of the position detecting optical system is decentered with respect to the optical axis of the position detecting optical system. .

In a third aspect of the present invention, there is provided an optical fiber according to the first or second aspect, further comprising an optical fiber arranged so that an end face on the light emitting side is near a pupil position of the position detecting optical system, and the light emitting side of the optical fiber. Is decentered with respect to the optical axis of the position detecting optical system.

According to a fourth aspect of the present invention, there is provided the optical fiber device according to any one of the first to third aspects, further comprising an optical fiber arranged so that an end surface on a light emitting side is near a pupil position of the position detecting optical system. It is characterized in that it has means for adjusting the eccentricity of the end face of the optical fiber on the light emission side.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, there is provided an aperture or a spatial filter arranged at a position conjugate with a pupil position of the position detecting optical system. The filter is decentered with respect to the optical axis of the position detecting optical system.

According to a sixth aspect of the present invention, in the first aspect of the present invention, there is provided an aperture or a spatial filter disposed at a position conjugate with a pupil position of the position detecting optical system. A driving device for driving the spatial filter is provided.

According to a seventh aspect of the present invention, there is provided an optical fiber according to any one of the first to sixth aspects, wherein the optical fiber is disposed such that an end surface on the light emitting side is near a pupil position of the position detecting optical system. An opening provided at a position where an image of the end face on the light emission side is formed, and having an opening smaller than the image of the end face.

An eighth aspect of the present invention is characterized in that, in the seventh aspect of the present invention, the opening is an opening that sets the σ of the position detecting optical system to 1 or less.

According to a ninth aspect of the present invention, in accordance with the seventh or eighth aspect of the present invention, there is provided an arithmetic processing device for calculating an optimum movement amount of the opening, and a driving device for driving the opening in accordance with a value calculated by the arithmetic processing device. Features.

According to a tenth aspect of the present invention, in the first aspect of the present invention, the position detecting optical system is TTL
Is a position detecting optical system.

According to an eleventh aspect of the present invention, in the invention of any one of the first to ninth aspects, the position detecting optical system is a TTR.
Is a position detecting optical system.

A twelfth aspect of the present invention is characterized in that, in the first aspect of the present invention, the position detecting optical system is an off-axis position detecting optical system.

According to a thirteenth aspect of the present invention, there is provided a position detecting apparatus for illuminating an object to be inspected with light from a photoelectric conversion element and a light source, and detecting reflected light from the object to form an image on the photoelectric conversion element. An optical system, comprising: a position detection device that detects the position of the test object based on an image signal detected by the photoelectric conversion element, wherein the position detection optical system has an aberration, The barycentric position of the light intensity distribution on the pupil plane of the position detection optical system of the light illuminating the test object is set so that the image signal of the test object acts in a direction to cancel the asymmetry due to the aberration. It is characterized by having.

According to a fourteenth aspect, in the thirteenth aspect, the center of gravity of the light intensity distribution on the pupil plane of the position detecting optical system is decentered with respect to the optical axis of the position detecting optical system. .

A fifteenth aspect of the present invention has an optical fiber according to the thirteenth or fourteenth aspect, wherein the optical fiber is disposed such that an end face on the light emitting side is near a pupil position of the position detecting optical system.
The end face of the optical fiber on the light emission side is eccentric with respect to the optical axis of the position detection optical system.

According to a sixteenth aspect of the present invention, there is provided the optical fiber device according to any one of the thirteenth to thirteenth aspects, further comprising an optical fiber arranged such that an end surface on the light emitting side is near a pupil position of the position detecting optical system. It is characterized in that it has means for adjusting the eccentricity of the end face of the optical fiber on the light emission side.

According to a seventeenth aspect of the present invention, in any one of the thirteenth to sixteenth aspects, there is provided an aperture or a spatial filter arranged at a position conjugate with a pupil position of the position detecting optical system. The filter is decentered with respect to the optical axis of the position detecting optical system.

According to a eighteenth aspect of the present invention, in any one of the thirteenth to seventeenth aspects, there is provided an aperture or a spatial filter disposed at a position conjugate with a pupil position of the position detecting optical system. A driving device for driving the spatial filter is provided.

According to a nineteenth aspect of the present invention, there is provided an optical fiber according to any one of the thirteenth to eighteenth aspects, wherein the optical fiber is disposed such that an end surface on the light emitting side is near a pupil position of the position detecting optical system. An opening having a smaller opening than the image of the end face is provided at a position where an image of the end face on the light emission side is formed.

According to a twentieth aspect of the present invention, in the nineteenth aspect, the opening is an opening that sets the σ of the position detecting optical system to 1 or less.

According to a twenty-first aspect of the present invention, in accordance with the nineteenth or twentieth aspect of the present invention, there is provided an arithmetic processing unit for calculating an optimal movement amount of the opening, and a driving device for driving the opening according to a value calculated by the arithmetic processing unit. Features.

According to a twenty-second aspect of the present invention, there is provided a projection exposure apparatus having the position detecting device according to any one of the thirteenth to twenty-first aspects, wherein the position of the wafer is determined based on the position of the object detected by the position detecting device. It is characterized by performing matching.

[0040]

FIG. 1 shows a projection exposure apparatus for manufacturing a semiconductor device according to a first embodiment of the present invention. In the figure,
The same components as those in the conventional example are denoted by the same symbols.
Although the x and y axes are taken in the surface of the wafer 4 as shown in the figure, since the position detection optical system of the projection exposure apparatus of the present embodiment measures in the x and y directions, only the measurement in the y direction will be described. I do.

In FIG. 1, light emitted from a light source 13 composed of a HeNe laser or another non-exposure light source enters an illumination optical system 11 through a fiber 12. The light is reflected by the polarizing beam splitter 10 into an S-polarized light component perpendicular to the plane of the paper, passes through the λ / 4 plate 7, and is converted into circularly polarized light. Thereafter, the light passes through the imaging optics 6, 5, the mirror 30, and the projection exposure optics 1, and the mark formed on the wafer 4 placed on the stage 2 which can be driven in the xyz directions or The reference mark 14 for adjustment is illuminated. The reflected light or the scattered light from the mark again passes through the projection exposure optical system 1, the mirror 30, and the imaging optical systems 5 and 6, and then passes through the λ / 4 plate 7, this time as P-polarized light which is a component in the paper. Is converted to Since the light is converted into P-polarized light, the light passes through the polarizing beam splitter 10 and forms an image of the mark on the photoelectric conversion element 9 such as a CCD camera by the imaging lens 8. The signal detected by the photoelectric conversion element 9 is subjected to image processing to detect the position of the mark, and the stage 2 is driven from the detected value to drive the wafer 4.
Are aligned.

The present invention provides a reference mark 1 for adjusting the optical center of gravity.
4 is provided on the stage 2. The reference mark 14 for adjustment is formed on a mechanism having the structure shown in FIG. That is, while the reference mark 14 is mounted on the second substrate 21, the second substrate 21
It is installed on a first substrate 23 via a strain sensor 22 such as a piezo element so that adjustment in the axial direction is possible, and the first substrate 23 is held by a rotating shaft 24.
Due to such a structure, it is possible to adjust the focus of the reference mark 14 by controlling the voltage applied to the piezo element 22, and to rotate the reference mark 14 by a predetermined angle. ing. In particular, the reference mark 14 is rotated 180 ° for observation, and compared with the observation before rotation, the reference mark 1
The effect of the asymmetry of the structure 4 itself is eliminated. In the present embodiment, a special mark such as an adjustment reference mark 14 is provided in the apparatus, so that measurement can be performed easily regardless of the wafer and a stable adjustment reference can be provided.

Here, the reference mark 14 for adjustment is specially provided on the stage 2, but the same is performed using a wafer having a similar mark or a wafer having a similar mark. It is also possible.

Although the optical center of gravity of the pupil plane of the position detecting optical system is symmetric with respect to the optical axis in a plane including the measurement direction, the position detecting optical system including the projection exposure optical system is decentered with respect to the light of the detection wavelength. Consider the case of having coma as an example. FIG. 6 is a schematic diagram of a detection signal obtained in the present embodiment. FIG. 6 (a)
Is a mark having a step shape in the cross section in the measurement direction and the illumination light 4
1 and scattered lights 42a and 42b in consideration of eccentric coma. FIG. 6B is an image signal of the reference mark in the state of FIG. The detection light from the mark edge has an asymmetric waveform with respect to the mark center. Here, assuming that the intensity of one edge is a, the intensity of the other edge is b, and the intensity of the entire mark is c, the evaluation value E is E = (ab) / c (1). The evaluation value E is considered as a parameter representing waveform distortion. Under such a definition, FIG. 7 shows the result of measuring the evaluation value E at this time by changing some step heights d of the alignment mark having a rectangular step structure made of silicon (Si). In the figure, the horizontal axis represents a step (height) d obtained by taking a modulus at the wavelength λ of the HeNe laser of the detection light, and the vertical axis represents the evaluation value E. As a result of the examination, it was confirmed from experiments and simulations that the evaluation value E changed periodically as shown in FIG. 7A.

On the other hand, FIG. 7B shows a state in which the position detecting optical system including the projection exposure optical system has no aberration and the step when the end face (pupil plane) of the fiber 12 shown in FIG. 1 is decentered. The evaluation value E is shown. The solid line shows the characteristic when the eccentricity of the optical center of gravity on the pupil plane is shifted by 3% of the NA of the detection system in the measurement direction, and the broken line similarly shows the characteristic when the eccentricity is 1.5%. The vertical and horizontal axes are the same as those in FIG. It can be seen that the evaluation value E changes with amplitude according to the amount of eccentricity of the optical center of gravity on the pupil plane. That is, when there is no aberration in the position detecting optical system, the optical center of gravity of the pupil plane is adjusted on the optical axis, so that it does not depend on the height of the step. It is possible to achieve a position detection optical system having a small dependent offset (inter-process offset).

FIGS. 7A and 7B both have similar sinusoidal characteristics. Therefore, when the position detecting optical system including the projection exposure optical system has an eccentric coma component, by adjusting the optical center of gravity in a direction to cancel the waveform distortion of the image signal based on the mark due to the eccentric coma, it is the same as the ideal case. Thus, it is possible to achieve a position detecting optical system which is not affected by the height of the step. 7A and 7B, the step is λ /
It was also found that the use of a mark having a step around 8, or 3λ / 8 enables sensitive and efficient adjustment of the optical center of gravity. In the actual adjustment, it is convenient to form a rectangular step mark using a Si wafer because the step amount d can be easily controlled. However, the same effect can be achieved by using another material and using a similar mark, that is, a mark having a rectangular step structure and having an interference phenomenon only at the edge portion with respect to the detection light. FIG.
Since the evaluation value for the step changes periodically as shown by, the effect is not limited to λ / 8 and λλ, and the same effect can be obtained by using an odd multiple of ８λ. ,
It can easily be inferred from this graph.

FIG. 5 is a flowchart showing the actual adjustment procedure. The adjustment is performed with a step of λ /
It can also be performed using a wafer having a step of about 8 or λ / 8. Here, the case where the reference mark 14 for adjustment is used will be described with reference to FIG.

First, the reference mark 14 for adjustment is driven to the focus position by using the piezo 22 in the initial state without rotation, and the image data of the reference mark 14 is captured. The measurement in this state is represented by a subscript _n ,
The resulting image de - height a _n of the data of the edge signal, b _n, if the total intensity of the signal and c _n, can be calculated evaluation value E _n from (1).

Next, the reference mark 14 for adjustment is connected to the rotating shaft 24.
, And focus driving is again performed by the piezo 22 to capture image data. The measurement in this state and be represented by the suffix _r, the obtained image de - height a _r a data edge signal, b _r, if the overall strength of the signal and c _r, (1) formula it can be calculated more evaluation values E _n. Thereafter, the two evaluation values are averaged, and E ₀ = (E _n + E _r ) / 2 (2) is set as the final evaluation value. The evaluation value E ₀ is equal to a predetermined criterion E _th
If it is smaller than this, the detection optical system is sufficiently adjusted, and the normal alignment routine can be continued. The criterion E _th is set in advance for each position detecting optical system as a criterion value such that the generated offset between processes is within an allowable range. If the evaluation value E ₀ does not satisfy the condition (2), information about the evaluation value E ₀ is displayed on a display such as a CRT. In this case, optimization of the optical center of gravity to the value of the evaluation value E ₀ due to insufficient adjustment of the position detecting optical system becomes less criterion E _th is repeated.

As described above, the reference mark 14 for adjustment is used.
By using the non-rotated image and the image rotated by 180 °, the influence of the offset caused by the asymmetry of the reference mark 14 used is eliminated. Therefore, when it is known in advance that the step structure of the reference mark 14 is completely symmetric with respect to the center of the mark, the operation of rotating and measuring by 180 ° can be omitted. In the case where the offset amount generated by the rotation of 180 ° is known in advance it is also omitted the rotation operation, instead to reflect the offset amount on the evaluation value E _n and can be obtained a final evaluation value E _0.

The description so far has been directed to one-way adjustment, that is, FIG.
Although the adjustment of the measurement in the y direction has been described, the final alignment must be performed two-dimensionally. In this case, the adjustment in the x direction orthogonal to the y direction, that is, the x direction in FIG. 1 can be similarly performed. That is, in the x direction, the adjustment reference mark 14 is rotated by 90 ° and 270 °, and the measurement is performed in two states different from each other by 180 ° as in the case of the y direction. Can cover both x and y directions. When one mark is used, the space is saved, and at the same time, the mark itself is common in two directions, which is practically large in terms of offset management.

FIG. 2 is a schematic view of a main part of a second embodiment of the present invention. The present embodiment is characterized in that a correction system for automatically optimizing the optical center of gravity by a position detecting device such as a projection exposure device for manufacturing semiconductor elements is provided. In FIG. 2, the same members as those described above are denoted by the same reference numerals. The most characteristic part of the present embodiment is the configuration of the illumination unit of the position detection optical system, and the other components are the same as those in FIG. 1.

After the light from the light source 13 emitted from the fiber 12 passes through the illumination system lens 15, an image of the fiber end face (pupil plane) is formed at least once in the illumination system 11. An aperture 1 at which the σ of the detection system is 1 or less is located at the imaging position.
6, or an equivalent spatial filter. The illumination system lens 15 forms an image of the fiber end face at the position of the opening 16 with a size sufficiently larger than the size of the opening.
By moving the position of the opening 16 in a direction orthogonal to the optical axis of the illumination system, the optical center of gravity can be adjusted, and an optimal position detection system is achieved.

The opening 16 is driven by calculating the optimum movement amount of the opening 16 by the arithmetic processing unit 17 based on the evaluation value E ₀ described in the first embodiment. According to the calculated value, the opening 16 is formed by using a driving device 53 such as a piezo element provided on the substrate 54.
And automatically and easily adjusts the position detection optical system with high accuracy.

Such an automatic correction sequence is preferably performed at the time of regular maintenance of the apparatus or when a problem occurs in the apparatus. If the measured value of the evaluation value E ₀ is larger than the criterion E _th , a closed loop sequence of the automatic correction is entered. If the measured value is smaller, the normal alignment loop is performed as described above.
Enter the chin.

FIG. 8 is a schematic view of a main part of a third embodiment of the present invention. In the embodiments described above, as the position detection optical system,
Although the so-called TTL off-axis system for detecting the position via the projection exposure optical system has been described, FIG. 8 shows a case where the present invention is applied to a simple off-axis position detection optical system not via the projection exposure optical system. I have. In the figure, the same reference numerals are given to the same components as those used in the above-described explanatory diagrams. The light emitted from the light source 13 is transmitted to the position detection optical system 5.
0 to illuminate the wafer or reference mark 14 for adjustment. The adjustment reference mark 14 is mounted on the stage 2 and has the structure shown in FIG. 9 as in the other embodiments. The reflected light from the reference mark 14 is imaged on a photoelectric conversion element 9 such as a CCD camera and converted into an electric signal. The arithmetic processing unit 17 calculates the value of the evaluation value E ₀ from the information obtained from the electric signal, and
Compare with _th . The subsequent procedure for determining whether to adjust the position of the optical center of gravity of the illumination system is described in the above two embodiments 1 and 2.
Is the same as

The mark on the wafer is passed through the reticle 51.
The so-called TTR on-axis position detection system for observing the laser beam has the same functions and means as those in the first to third embodiments, so that the adjustment state of the detection optical system can be checked and the position detection accuracy can be improved. .

[0058]

As described above, according to the present invention, a position detecting optical system in a position detecting apparatus such as a projection exposure apparatus for manufacturing a semiconductor device is constituted by an illumination system whose optical center of gravity can be adjusted. By observing the image signal and optimizing the illumination conditions, it is possible to improve the position detection accuracy of the mark. Further, in the present invention, the adjustment state of the position detecting optical system can be automatically and easily evaluated by arranging an adjustment reference mark having predetermined conditions on a stage in order to obtain a specific image signal. Was made possible. If the adjustment is poor, the position of the opening of the illumination system in the position detection optical system is moved in the direction perpendicular to the optical axis to optimize the optical center of gravity of the detection optical system, and various error components can be cancelled. A position detection device with a small offset between processes is realized to improve the position detection accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a position detection device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a position detection device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional position detection device.

FIG. 4 is a diagram showing a relationship between an alignment mark, illumination light, and a signal.

FIG. 5 is a flowchart for optimizing the optical center of gravity.

FIG. 6 is a detection signal when the position detection optical system has an aberration.

FIG. 7 is a diagram showing a relationship between a mark step amount and an evaluation amount according to an adjustment state of a position detection optical system.

FIG. 8 is a configuration diagram of a position detection device according to a third embodiment of the present invention.

FIG. 9 is a configuration diagram of an adjustment reference mark arranged on the stage.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Projection exposure optical system 2 XYZ stage 3 Wafer chuck material 4 Wafer 5 Detection optical system 6 Detection optical system 7 λ / 4 plate 8 Imaging optical system 9 Photoelectric conversion element 10 Polarization beam
Musplitter 11 Illumination optical system 12 Fiber 13 Light source 14 Adjustment reference mark 15 Illumination lens 16 Opening 17 Arithmetic processing unit 21 First substrate 22 Distortion element 23 Second substrate 24 Rotating axis 30 Mirror 31 Alignment mark Mark 32 illumination light 34 mark center 41 illumination light 42 edge scattered light 50 position detection optical system 51 reticle 52 exposure illumination system 53 driving device 54 driving substrate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 BB02 BB27 CC19 FF01 GG05 JJ03 JJ26 LL02 LL12 LL33 LL36 PP12 UU01 5F046 BA04 CB04 CB09 CB26 DA13 DB05 EB03 FA10 FA16 FA17 FB14 FB17

Claims (22)

[Claims] 1. A photoelectric conversion device comprising: a photoelectric conversion element; and a position detection optical system that illuminates a test object with light from a light source and forms an image of reflected light from the test object on the photoelectric conversion element. A projection exposure apparatus that detects a position of the test object based on an image signal detected by a photoelectric conversion element, and performs wafer positioning based on the detected position of the test object, wherein the position detection optical system Has an aberration, the image signal of the test object, the light in the pupil plane of the position detection optical system of the light illuminating the test object so as to act in a direction to cancel the asymmetry due to the aberration A projection exposure apparatus wherein a position of a center of gravity of an intensity distribution is set. 2. The projection exposure apparatus according to claim 1, wherein the position of the center of gravity of the light intensity distribution on the pupil plane of the position detection optical system is eccentric with respect to the optical axis of the position detection optical system. 3. An optical fiber disposed so that an end face on a light emission side is near a pupil position of the position detection optical system,
3. The projection exposure apparatus according to claim 1, wherein an end surface of the optical fiber on a light emission side is decentered with respect to an optical axis of the position detection optical system. 4. An optical fiber disposed so that an end face on a light emission side is near a pupil position of the position detection optical system,
The projection exposure apparatus according to claim 1, further comprising a unit configured to adjust an eccentricity of an end face of the optical fiber on a light emission side. 5. An apparatus according to claim 1, further comprising an aperture or a spatial filter disposed at a position conjugate with a pupil position of said position detecting optical system, wherein said aperture or spatial filter is decentered with respect to an optical axis of said position detecting optical system. The method according to any one of claims 1 to 4, wherein
Item 3. The projection exposure apparatus according to Item 1. 6. The apparatus according to claim 1, further comprising an opening or a spatial filter disposed at a position conjugate with a pupil position of said position detecting optical system, and a driving device for driving said opening or said spatial filter. The projection exposure apparatus according to any one of claims 1 to 5, 7. An optical fiber disposed so that an end face on the light emitting side is near a pupil position of the position detection optical system, and provided at a position where an image of the end face on the light emitting side of the optical fiber is formed. 7. The projection exposure apparatus according to claim 1, further comprising an opening having an opening smaller than the image of the end face. 8. The projection exposure apparatus according to claim 7, wherein the opening is an opening that makes σ of the position detection optical system equal to or less than 1. 9. A projection exposure apparatus according to claim 7, further comprising an arithmetic processing unit for calculating an optimal movement amount of said opening, and a driving device for driving said opening in accordance with a value calculated by said arithmetic processing unit. apparatus. 10. The projection exposure apparatus according to claim 1, wherein said position detecting optical system is a TTL position detecting optical system. 11. The projection exposure apparatus according to claim 1, wherein the position detection optical system is a TTR position detection optical system. 12. The apparatus according to claim 1, wherein said position detecting optical system is an off-axis position detecting optical system.
The projection exposure apparatus according to claim 1. 13. A photoelectric conversion device comprising: a photoelectric conversion element; and a position detection optical system that illuminates a test object with light from a light source and forms an image of reflected light from the test object on the photoelectric conversion element. A position detection device that detects a position of the test object based on an image signal detected by a photoelectric conversion element, wherein the position detection optical system has an aberration, and an image signal of the test object, Position detection, wherein a center of gravity of a light intensity distribution on a pupil plane of the position detection optical system of light illuminating the test object is set so as to act in a direction to cancel the asymmetry due to the aberration. apparatus. 14. The position detecting apparatus according to claim 13, wherein the position of the center of gravity of the light intensity distribution on the pupil plane of said position detecting optical system is decentered with respect to the optical axis of said position detecting optical system. 15. An optical fiber disposed so that an end face on a light emitting side is near a pupil position of the position detecting optical system, and an end face on a light emitting side of the optical fiber is located on an optical axis of the position detecting optical system. The position detecting device according to claim 13, wherein the position detecting device is eccentric with respect to the position. 16. An optical fiber disposed so that an end face on the light emitting side is near a pupil position of the position detecting optical system, and means for adjusting eccentricity of the end face on the light emitting side of the optical fiber is provided. 16. The method according to claim 13, wherein:
The position detecting device according to any one of claims 1 to 7. 17. An apparatus according to claim 17, further comprising an aperture or a spatial filter arranged at a position conjugate with a pupil position of said position detecting optical system, wherein said aperture or spatial filter is decentered with respect to an optical axis of said position detecting optical system. The position detecting device according to any one of claims 13 to 16, wherein: 18. The apparatus according to claim 13, further comprising an opening or a spatial filter disposed at a position conjugate with a pupil position of said position detecting optical system, and a driving device for driving said opening or said spatial filter. 18. The position detection device according to any one of claims 17 to 17. 19. An optical fiber disposed so that an end face on the light emission side is near a pupil position of the position detection optical system, and a position where an image of the end face on the light emission side of the optical fiber is formed. 19. The position detecting device according to claim 13, further comprising an opening having an opening smaller than an image. 20. The aperture as described above, wherein σ of the position detecting optical system is 1
20. The position detecting device according to claim 19, wherein the opening is as follows. 21. An apparatus according to claim 1, further comprising an arithmetic processing unit for calculating an optimal movement amount of said opening, and a driving device for driving said opening in accordance with a value calculated by said arithmetic processing unit.
21. The position detecting device according to 9 or 20. 22. A position detecting device according to claim 13, wherein the position of the wafer is adjusted based on the position of the test object detected by the position detecting device. Projection exposure equipment.