JP2001250766A - Position measuring device, projection aligner, and exposure method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position measuring device, a projection aligner, and an exposure method for accurately detecting mark position information even if a mark is formed as designed by measuring the mark position information for each order, even if a light source in a wide wavelength band is the light source of illumination light without causing increase in the scale of the device configuration of an optical system. SOLUTION: An alignment sensor 12 applies illumination light IL to an alignment mark AM that is formed on a wafer W, and picks up the image of the alignment mark being generated by applying the illumination light IL for generating an image signal. A position operation unit 27 extracts odd-order of harmonics based on the image signal, and obtains the position information of the alignment mark AM based on the extracted, odd-order of harmonics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position measuring device for measuring position information of an alignment mark formed on an object such as a wafer, and a position of the object based on the position information measured by the position measuring device. The present invention relates to an exposure apparatus and an exposure method for performing alignment of a mask with each shot area on a wafer, exposing the mask to exposure light, and transferring an image formed on a reticle onto an object.

[0002]

2. Description of the Related Art When a device such as a semiconductor device or a liquid crystal display device is manufactured by a photolithography process, a pattern image of a photomask or a reticle (hereinafter collectively referred to as a "reticle") is formed on a photosensitive substrate through a projection optical system. The projection exposure apparatus for projecting each shot area is used. In recent years, as a projection exposure apparatus of this type, a photosensitive substrate is placed on a two-dimensionally movable stage, and the stage is moved (stepped) by the stage, so that a reticle pattern image is formed on the photosensitive substrate. A so-called step-and-repeat type exposure apparatus that repeats the operation of sequentially exposing each shot area, for example, a reduction projection type exposure apparatus (stepper) is frequently used. In recent years, a step of performing scanning exposure by synchronously scanning a reticle and a substrate at the time of exposure has been proposed.
An and scan type exposure apparatus is also used.

In order to transfer a reticle pattern image to a predetermined position using these exposure apparatuses, it is necessary to detect the position of the reticle or the substrate with high accuracy. In recent years, particularly in the manufacture of semiconductor devices, patterns to be formed have become finer, and there has been a demand for improved alignment accuracy in order to manufacture semiconductor devices having desired performance. An alignment mark for detecting the position is formed on the substrate or the reticle, and the exposure apparatus includes an alignment sensor that detects the position information of the reticle or the substrate by detecting the position information of these alignment marks. .

An alignment sensor that detects positional information of a substrate changes the surface state (roughness) of the substrate to be measured in a manufacturing process of a semiconductor element, a liquid crystal display element, or the like. It is difficult to accurately detect position information, and different devices are generally used according to the surface condition of the substrate. The main components of these devices are LSA (Laser Step Alignment), FIA (Field Image Alignment), and LIA (L
aser Interferometric Alignment) method.
An LSA type alignment sensor is an alignment sensor that irradiates an alignment mark formed on a substrate with a laser beam and measures the position information of the alignment mark by using diffracted and scattered light. Widely used for semiconductor wafers in the process. FIA
Alignment sensor illuminates the alignment mark using a light source with a wide wavelength band such as a halogen lamp, converts the resulting image of the alignment mark into an image signal, performs image processing, and performs position measurement. The alignment sensor is effective for measuring an asymmetric alignment mark formed on an aluminum layer or a substrate surface. The LIA type alignment sensor irradiates a diffraction grating alignment mark formed on the substrate surface with laser light having slightly different wavelengths from two directions, and causes the resulting two diffracted lights to interfere with each other. This is an alignment sensor that detects the position information of the alignment mark from the phase. This LIA type alignment sensor is effective when used for an alignment mark with a low step or a substrate having a large surface roughness.

[0005]

The generally used alignment mark is a so-called line-and-space alignment mark in which a rectangular convex or concave portion is formed on the substrate surface. The position information is obtained by detecting the center position of the alignment mark in consideration of the edge position of each line and the like. Therefore, for example, when the position of each line of the alignment mark is not formed as designed, that is, when a process offset occurs, the center position of the alignment mark is detected as being shifted. The process offset is preferably as small as possible in order to improve the position detection accuracy of the alignment mark.

In recent years, in order to improve the accuracy of detecting the position information of the alignment mark, a technique has been devised which utilizes high-order diffracted light generated when the alignment mark is irradiated with illumination light. FIG. 14 is a diagram for explaining a conventional technique for improving the position information detection accuracy of an alignment mark by using higher-order diffracted light. In FIG. 14, reference numeral 100 denotes a substrate on which an alignment mark 101 is formed.
4 shows the cross-sectional shape. The alignment mark 101 has a plurality of grooves formed by etching a part of the substrate 100.

In FIG. 14, reference numeral 105 denotes a diffracted light 10 generated when the alignment mark 101 is irradiated with illumination light.
2a, 102b, 103a, 103b, 104a, 10
4B illustrates a lens system that converts 4b into parallel light. The diffracted lights 102a and 102b are + 1st-order and -1st-order diffracted lights, respectively, and the diffracted lights 103a and 103b are +
These are second- and second-order diffracted lights, and the diffracted lights 104a, 104a
4b is +3 order and -3 order diffracted light, respectively.

Reference numeral 106 denotes the incident diffracted light 102a, 102
b, 103a, 103b, 104a, and 104b are diffracted in different directions for each order.
b, 108a, 108b, and 109 are wedge plates formed. The wedge plate 106 is provided to separate the diffracted light from the alignment mark 101 for each order including the sign. Reference numeral 110 denotes a lens system that collects the diffracted light of each order diffracted by the wedge plate 106. 11
1, 112, and 113 are light receiving devices provided to receive the first-order diffracted light, the second-order diffracted light, and the third-order diffracted light, respectively.

In the conventional apparatus having the above-described structure, first, diffraction light 102a, 102b, 103a, 103b, 104a, 104a,
104b is converted into parallel light by a lens system 105 and made incident on a wedge plate 106, and the diffracted lights 102a, 102b, 1
The light is diffracted in different directions for each sign and order of 03a, 103b, 104a, and 104b. That is, the wedge plate 106 diffracts the first-order, second-order, and third-order diffracted lights in different directions, respectively, but also diffracted lights having different signs even if the order is the same, for example, + 1st order and-. The first order diffracted light is diffracted in a different direction.

The light diffracted by the wedge plate 106 is transmitted to the lens system 110.
, The + 1st-order and -1st-order diffracted light are
11 and the +2 order and −2 order diffracted light are
12 and the +3 order and −3 order diffracted light are
The light is condensed by the lens system 110 so as to be incident on the lens 13. Therefore, the light receiving device 111 receives the interference light between the + 1st-order diffracted light and the −1st-order diffracted light, the light receiving device 112 receives the interference light between the + 2nd-order diffracted light and the −2nd-order diffracted light, and the light receiving device 113 outputs the interference light. +
Interference light between the third-order diffracted light and the third-order diffracted light is detected.

The alignment mark 110 shown in FIG.
Is that the surface position in the Z direction periodically changes stepwise according to the position in the X direction. When a Fourier transform is performed on an alignment mark having a spatially changing shape as described above, Fourier components having different spatial frequencies in the X direction are generated, and the diffracted light of each order is affected by each Fourier component. That is, assuming that the length of one line and the length of one space in the X direction is a basic period, and a spatial frequency corresponding to the basic period is a basic frequency, for example, 1
The next diffracted light is strongly affected by the Fourier component corresponding to the fundamental frequency.

Each of the Fourier components included when the alignment mark is subjected to Fourier transform differs between a case where no process offset has occurred in the alignment mark and a case where a process offset has occurred. When the diffracted light from the alignment mark 101 is measured without being separated for each order, there is only one measurement result. By performing measurement separately for each order, the measurement result for each order can be obtained. Obtainable. In the above-described conventional technology, the position information of the alignment mark is measured for each order, and the final position information of the alignment mark is taken into account in consideration of the measured position information for each order. Based on this, the position information of the alignment mark is measured with higher accuracy than when the position information of the alignment mark is obtained. For details of the above prior art, see International Publication No. WO 98/396 based on the provisions of the Patent Cooperation Treaty.
See 89.

In the prior art described above, the diffracted light from the alignment mark 101 is transmitted to the lens system 105, the wedge plate 106,
Since it is optically separated into diffracted light of each order using the lens system 110 and the plurality of light receiving devices 111 to 113,
The device scale becomes large. As described above, since the exposure apparatus generally uses a different apparatus according to the surface state of the substrate to detect the position information of the alignment mark formed on the substrate, the external shape of the apparatus is as small as possible. Is more desirable.

Further, as shown in FIG. 14, when the diffracted light is separated into the diffracted light of each order using an optical device, there is a problem that the light source is restricted. Current,
In order to reduce the influence of interference by the resist applied to the substrate surface, an FIA type alignment sensor using a halogen lamp having a wide wavelength band as a light source of illumination light is often used. However, in general, the lens system 10
5. Since the wedge plate 106 and the lens system 106 have a so-called dispersion characteristic in which the refractive index changes as the wavelength changes,
When diffracted light enters these, the diffraction angle differs for each wavelength, and it becomes difficult to separate the diffracted light for each order. As a result, it becomes impossible to measure the position information for each order, so that the position information cannot be measured with high accuracy.

[0015] The present invention has been made in view of the above circumstances, and even if a light source having a wide wavelength band is a light source of illumination light without inviting an increase in the scale of an optical system configuration.
By measuring the position information of the mark for each order, a position measurement device capable of detecting the position information of the mark with high accuracy even when the mark is not formed as designed has been provided. An object of the present invention is to provide an exposure apparatus and an exposure method for performing an exposure process by aligning an object using mark position information.

[0016]

In order to solve the above-mentioned problems, a position measuring apparatus according to the present invention provides an irradiation system for irradiating a mark (AM) formed on an object (W) with a detection beam (IL). Means (13, 14, 15, 19, 20) and the mark (A) generated by irradiation of the detection beam (IL).
M) to capture an image of M) and generate an image signal.
2), extracting means (27) for extracting an odd-order harmonic based on the image signal, and the mark (A) based on the odd-order harmonic extracted by the extracting means (27).
M) for calculating position information. According to the present invention, the harmonics of each order diffracted by the mark are not separated using optical means, but are converted into image signals by the imaging means, and then the odd harmonics are extracted by the extracting means. Therefore, even when the light source having a wide wavelength band is the light source of the illumination light, it is possible to extract the odd-order harmonics without increasing the size of the device configuration of the optical system. Since the position information of the mark is measured based on the extracted odd-order harmonics, the position information of the mark can be detected with high accuracy even when the mark is not formed as designed. Further, according to the present invention, the extracting means (27)
The image processing apparatus further includes a separation unit (28) that performs Fourier transform on the image signal and separates harmonics included in the image signal for each order. Further, the position measuring device of the present invention,
The extracting means (27) further includes a changing means (29) for changing an imaging condition at the time of imaging by the imaging means (12) so as to obtain a phase difference image signal having a phase difference with respect to the image signal. It is characterized by including. According to the present invention, even when odd harmonics are hardly included due to lighting conditions and the like, odd harmonics can be included by changing the phase difference. However, the measurement can be performed well. Also, in the position measuring device according to the present invention, the image pickup means (12) converts the optical image of the mark (AM) into an image signal (2).
6), and a phase difference generating means (17) that can be inserted into and removed from the imaging optical path between the image sensor (26) and the object (W). A first condition for disposing the phase difference image signal in the imaging optical path; and a second condition for disposing the phase difference image signal in the imaging optical path. Features. Further, in the position measuring device according to the present invention, the imaging means (12) includes an imaging element (26) for converting an optical image of the mark (AM) into an image signal, and the changing means (29) The object (W) is displaced with respect to the in-focus position of the element (26). Further, the position measuring device of the present invention is characterized in that the extracting means (2
7) further includes comparing means (30) for comparing odd-order harmonics contained in the image signal with odd-order harmonics contained in the phase difference image signal, and the arithmetic means (3)
1) is characterized in that the position information of the mark (AM) is obtained based on the odd-order harmonics extracted from the image signal containing a larger number of the odd-order harmonics. Further, the position measuring device of the present invention may be configured such that:
However, in the extracted odd-order harmonics, position information of the mark (AM) is obtained for each order of the harmonics. Further, in the position measuring device according to the present invention, the arithmetic means (31) is configured to calculate a plurality of mark positions calculated for each of the orders based on predetermined conditions relating to the formation conditions of the mark (AM) or the mark (AM). It is characterized in that mark position information obtained from a harmonic of a specific order is extracted from the information, and the position of the mark (AM) is determined based on the extracted mark position information. Further, the position measuring device of the present invention may be configured such that:
Obtains an average value of the mark position information obtained for each of the orders, and uses an order other than the order corresponding to the mark position information indicating that the deviation from the average value is equal to or more than a predetermined amount, to determine the position of the mark (AM) It is characterized by seeking. An exposure apparatus according to the present invention is an exposure apparatus that transfers a predetermined pattern onto a substrate (W), and includes positional information of the mark (AM) formed on the substrate (W) obtained by the position measuring device. Based on the predetermined pattern and the substrate (A
M) and an alignment device (7, 1)
1), wherein the aligned substrate (W) is exposed with the predetermined pattern.
According to the exposure method of the present invention, a mark (AM) formed on a substrate (W) is irradiated with a detection beam (IL), and the mark (A) generated by irradiation of the detection beam (IL) is irradiated.
M), and an image signal is generated (S14, S1).
8) Odd-order harmonics are extracted based on the image signal (S14, S18), and position information of the mark (AM) is obtained based on the extracted odd-order harmonics (S14).
22) A predetermined pattern and the substrate (W) are aligned based on the position information of the mark (AM), and the aligned substrate (W) is exposed with the predetermined pattern. .

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a position measuring apparatus, an exposure apparatus and an exposure method according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an overall configuration of an exposure apparatus according to an embodiment of the present invention in which a position measuring device according to an embodiment of the present invention is used. In the present embodiment, a step-and-repeat type exposure apparatus including an off-axis type alignment sensor as an alignment sensor will be described as an example. In the following description, the XYZ rectangular coordinate system shown in FIG. 1 is set, and the positional relationship of each member will be described with reference to the XYZ rectangular coordinate system. In the XYZ orthogonal coordinate system, the X axis and the Z axis are set to be parallel to the paper surface, and the Y axis is set to a direction perpendicular to the paper surface. In the XYZ coordinate system in the figure, the XY plane is actually set to a plane parallel to the horizontal plane, and the Z axis is set vertically upward.

In FIG. 1, exposure light EL emitted from an illumination optical system 1 illuminates a reticle R as a mask with substantially uniform illuminance. The reticle R is held on a reticle stage 3, and the reticle stage 3 is supported so as to be able to move and minutely rotate in a two-dimensional plane on a base 4.
A main control system 10 that controls the operation of the entire apparatus controls the operation of the reticle stage 3 via a driving device 5 on the base 4.

Under the exposure light EL, a pattern image of the reticle R is projected onto each shot area on the wafer W via the projection optical system PL. The wafer W is mounted on a wafer stage 7 via a wafer holder 6. The wafer stage 7 holds the wafer W in a plane perpendicular to the optical axis of the projection optical system PL.
XY stage for two-dimensionally positioning the projection optical system P
It comprises a Z stage for positioning the wafer W in a direction (Z direction) parallel to the optical axis of L, a stage for slightly rotating the wafer W, and the like.

A movable mirror 8 is fixed on the upper surface of the wafer stage 7, and a laser interferometer 9 is arranged to face the movable mirror 8. Although shown in a simplified manner in FIG. 1, the movable mirror 8 is composed of a plane mirror having a reflection surface perpendicular to the X axis and a plane mirror having a reflection surface perpendicular to the Y axis. Also,
The laser interferometer 9 includes two X-axis laser interferometers that irradiate the movable mirror 8 with a laser beam along the X-axis and a Y-axis laser that irradiates the movable mirror 8 with a laser beam along the Y-axis. The wafer stage 7 is constituted by one laser interferometer for the X axis and one laser interferometer for the Y axis.
Are measured. Further, the difference between the measured values of the two laser interferometers for the X axis causes the wafer stage 7
Is measured.

X coordinate measured by the laser interferometer 9,
The information of the Y coordinate and the rotation angle is supplied to the main control system 10,
The main control system 10 controls the positioning operation of the wafer stage 7 via the drive system 11 while monitoring the supplied coordinates. Although not shown in FIG. 1, the same reticle side interferometer system as the wafer side is provided.

On the side of the projection optical system PL, an off-axis alignment sensor 12 is arranged. In this alignment sensor 12, illumination light from a light source 13 such as a halogen lamp is converted into parallel light by a collimator lens 14. After being reflected by the half mirror 15, the light enters the retarder turret 16. Retarder turret 1
6 has a phase difference plate 17. FIG. 2 is a cross-sectional view of the retarder turret 16. The retardation plate turret 16 has an opening OP1 and an opening OP2, and a retardation plate 17 is fixed to a center portion of the opening OP2 by a support rod. The phase difference plate turret 16 is rotatable about the rotation axis C1 by the actuator 18, and is arranged such that the optical axis of the illumination light IL is positioned within the opening OP1 or OP2 by the rotating operation. The phase difference plate 17 delays the phase of the reflected light not passing through the phase of the reflected light passing through the phase difference plate 17 by 90 degrees. Although the reason for providing the phase difference plate 17 will be described later in detail, it is for changing the odd-order Fourier component included in the reflected light including the information on the shape of the alignment mark generated when the illumination light IL is incident and illuminated. The rotation operation of the phase difference plate turret 16 is controlled by a position calculation unit 27 described later.

The illumination light IL transmitted through the phase difference plate turret 16 is reflected by a mirror 19 and condensed by an objective lens 20 to illuminate the alignment mark AM on the wafer W with incident light. When the illumination light IL illuminates the alignment mark, reflected light is generated. The reflected light from the alignment mark AM reaches the retarder turret 16 via the objective lens 20 and the mirror 19. Here, as shown in FIG. 1, since the reflected light is traveling backward in the optical path of the illumination light IL, the reflected light passes through the opening OP1 or OP2 of the phase difference plate 16. The reflected light when the reflected light simply passes through the opening OP1 in a state where the optical axis of the illumination light IL is disposed in the opening OP1, and the reflected light when the optical axis of the illumination light IL is disposed in the opening OP2. A 90-degree phase difference occurs between the light and the reflected light when passing through the phase difference plate 17.

The reflected light passing through the phase difference plate turret 16 enters the mirror 21 via the half mirror 15. The reflected light that has entered the mirror 21 has its optical axis bent, travels in the Z-axis direction in the figure, and is imaged on the index plate 23 by the lens system 22. On the index plate 23, an index mark serving as a reference when measuring the position information of the alignment mark AM is formed. Objective lens 20 and lens system 2
2 and conjugate with the wafer W. The image of the alignment mark of the wafer W and the index mark are formed by a relay system 2
An image is formed on the image pickup surface of the image pickup element 26 via 4 and 25. For example, a two-dimensional CCD (Charge Coupl
ed Device) is used.

The image pickup device 26 converts an optical image formed on the image pickup surface into an electric signal. The electric signal converted by the image sensor 26 is output to the position calculation unit 27 as an image signal. The position calculation unit 27 performs various kinds of signal processing on the image signal output from the image sensor 26 to obtain the position information of the alignment mark AM by calculation. FIG.
3 is a block diagram showing an internal configuration of the position calculation unit 27. FIG. As shown in FIG. 3, the position calculation unit 27
Is a Fourier transform unit 28, a switching control unit 29, a comparison unit 3
0 and a position calculation unit 31.

The Fourier transform unit 28 performs a Fourier transform process on the image signal output from the image sensor 26,
Each Fourier component is separated and extracted for each order. In the following description, a first-order or higher Fourier component is referred to as a harmonic component. The Fourier transform unit 28 outputs a signal indicating the end of the conversion to the switching control unit 29 when the input image signal is Fourier transformed. When a signal indicating that the Fourier transform has been completed is input from the Fourier transform unit 28, the switching control unit 21 controls the actuator 18 to control the opening OP
The phase difference plate turret 16 is rotated so that either 1 or the opening OP2 includes the optical axis of the illumination light IL.

In this embodiment, the switching control unit 2
9, the phase difference plate turret 16 is rotated to generate a phase difference depending on whether the reflected light from the wafer W passes through the opening OP1 or passes through the opening OP2 in which the phase difference plate 17 is arranged. The method of cleaning the phase difference is not limited to this method. For example, the retarder turret 16 is fixed so that the reflected light from the wafer W passes through the opening OP1, and the switching control unit 29 requests the main control system 10 to change the position of the wafer W in the Z-axis direction. The main control system 10 drives the wafer stage 7 via the drive system 11 to change the position of the wafer W in the Z-axis direction, thereby generating a phase difference of the reflected light. Is also good. When changing the position of the wafer W in the Z-axis direction, the position of the wafer W
Is preferably moved. In the following description, the operation of detecting reflected light from the wafer W through the opening OP1 and detecting the reflected light from the image sensor 26 is referred to as normal observation.
The operation of detecting the reflected light from the image sensor 26 through the aperture OP2 and detecting the reflected light with the image sensor 26 is referred to as phase difference observation.

The comparison unit 30 Fourier-transforms the harmonics of each order obtained by Fourier-transforming the detection result of the imaging device 26 obtained by performing normal observation and the detection result of the imaging device 26 obtained by performing phase-difference observation. Compare with the harmonics of each order,
It is determined in which case the odd-order harmonics are more frequently included. Here, in the present embodiment, among the harmonics of each order that are separated and extracted, the odd-order harmonics are focused on to improve the measurement accuracy. Hereinafter, the principle will be described.

Now, consider a periodic structure having the shape shown in FIG. FIG. 4 is a diagram generalizing the periodic structure of the alignment mark AM. The optical image formed on the image sensor 26 includes information on the structure of the alignment mark AM, and the periodic structure shown in FIG.
It can be considered as a waveform of information on the structure of M. When the Fourier transform is performed on the periodic structure shown in FIG. 4 and expressed using a Fourier component of a natural order,
The function A (x) representing the periodic structure is represented by the following equation (1).

(Equation 1)

Here, the symbol ω in the above equation (1) is the spatial angular frequency in the x-axis direction of the periodic structure, and the symbol Φ is the phase component of the periodic structure shown in FIG. FIG.
In the above, harmonics up to the ninth order are considered. This is because it is considered sufficient to consider the numerical order of the objective lens 20 up to the ninth order.
In other words, the diffracted light of the ninth or higher order is diffracted at an angle equal to or larger than the numerical aperture of the objective lens 20, so that it is considered that the diffracted light cannot be collected by the objective lens 20.

The image sensor 20 detects the intensity of the optical image formed on the light receiving surface and outputs it as an image signal. The intensity image I (x) of the above equation (1) is obtained from the following equation (2).

(Equation 2) Here, the PSF in the equation (2) is a point spread function (Point-Sp
read function), which indicates the shape of the intensity distribution of the image when an infinitesimal point is formed by the optical system, and is a type of image forming characteristic of the optical system. is there. The optical system referred to here is an optical system that causes the reflected light of the wafer W to travel from the objective lens 20 to the image sensor 26. Since the image formed in the optical system is obtained by the convolution of the object (specimen) and the PSF, to obtain the intensity image, as shown in the equation (2), the function A (x) representing the periodic structure is obtained. It is determined by the convolution of the absolute value and the PSF. When the square of the absolute value of the function A (x) representing the periodic structure shown in the equation (1) is obtained, the following equation (3) is obtained.

[0032]

(Equation 3) By substituting the absolute value of the function A (x) representing the periodic structure obtained by the equation (3) into the equation (2), the following equation (4) is obtained.

[0033]

(Equation 4) Here, in equation (4), the variable DC means a DC component, that is, a component that does not depend on the position x, and the variable AC means an AC component that changes depending on the position x. The value of the variable DC is B ₃ ^2, variable AC is expressed by the following equation (5).

[0034]

(Equation 5)

Equation (4) is an equation representing the intensity image I (x), and the component that changes depending on x in the equation (4) is expressed by equation (5). Therefore, by referring to the equation (5), it is possible to obtain what order harmonics are included and how much. Referring to the equation (5), the components appearing are all even-order harmonics, and at first glance, it seems that no odd-order harmonics are included. For example, the first term on the right side of the equation (5) (the term surrounded by curly braces “｛” and curly braces “｝”) is the sum of the second, sixth, tenth, and eighteenth even harmonics. It is represented by However, even-order harmonics can be represented by a combination of odd-order harmonics and odd-order harmonics.
For example, the following combinations can be considered for the second harmonic. Combination of 1st harmonic and 1st harmonic: 1+
(+1) = 2 Combination of 3rd harmonic and -1st harmonic: 3+
(-1) = 2 Combination of fifth harmonic and third harmonic: 5+
(−3) = 2 Combination of 7th harmonic and −5th harmonic: 7+
(−5) = 29 Combination of 9th harmonic and −7th harmonic: 9+
(-7) = 2

As described above, even-order harmonics are represented by a combination of odd-order harmonics, and odd-order harmonics are originally formed by odd-order diffracted light. Focusing on this point, the present embodiment is based on the principle that the position information of the alignment mark AM is measured based on odd-order harmonics that are not easily affected by the process offset. Therefore, if the order of the odd-order harmonic to be determined is specified and the combination of the odd-order terms included in each even-numbered term in the equation (5) is considered, the odd-order harmonic in the specified order can be obtained. By the way, referring to the equation (3), when the value of θ becomes an integral multiple of 90 degrees, odd harmonics are not included. As described above, since odd harmonics are not included at all depending on the measurement conditions of the alignment sensor 12, the occurrence of this problem is prevented by changing the phase of the reflected light using the phase difference plate 17. .

In general, when an odd-order harmonic is included, the alignment mark AM is detected as a single mark. FIG. 5 is a diagram illustrating an example of a waveform of an image signal obtained when the alignment mark AM is detected by the image sensor 26. When the alignment mark AM is formed in the shape shown in FIG. 5 in the single mark, the signal strength of the portion of the alignment mark AM marked with the symbol S1 is small, and the signal strength of the portion marked with the symbols L1 and L2 is small. Is a signal M1 in which the signal strength is increased. That is, the single mark is located at the edge position E of the alignment mark AM.
The signal has a rising portion or a falling portion of the signal strength at 1 and the edge position E2. In addition, the symbol M in FIG.
The signal denoted by 2 is a signal waveform when the alignment mark AM is detected as a double mark. As shown in FIG. 5, the double mark is a signal whose signal intensity is minimal at the edge positions E1 and E2 of the alignment mark AM.

In order to detect the position of the alignment mark AM, it may be necessary to detect the edge position of the alignment mark AM from the detection signal output from the image sensor 26. As a result of detecting the same alignment mark AM, the signal waveform may become a single mark or a double mark shown in FIG. In general, since a single mark includes an odd-order harmonic, an algorithm for edge detection can be made constant by using a detection result in a case where a large number of odd-orders are included using the above-described method. There is also an advantage.

FIG. 6 is a diagram showing a waveform of an image signal measured under a certain illumination condition. In FIG. 6, a curve denoted by reference numeral P1 schematically shows a cross-sectional shape of the alignment mark AM, and a curve denoted by reference numeral D1 is a waveform of an image signal. As shown, under this illumination condition, the waveform D1 of the image signal is measured as a substantially single mark. FIG. 7 is a diagram showing harmonic components of each order obtained by performing a Fourier transform on the waveform D1 of the image signal shown in FIG. As shown in FIG. 7, it can be seen that odd harmonics are included. In particular, the first, third, and fifth harmonics are included.

FIG. 8 is a diagram showing a waveform of an image signal measured under illumination conditions different from those in FIG. In FIG. 8, a curve denoted by reference symbol P2 schematically shows a cross-sectional shape of the alignment mark AM, and a curve denoted by reference symbol D2 is a waveform of an image signal. Under this illumination condition, the waveform D2 of the image signal is measured as a double mark rather than a single mark. Therefore, the waveform D2 of the image signal has the minimum value at the edge position of the alignment mark AM. FIG. 9 is a diagram showing harmonic components of each order obtained by performing a Fourier transform on the waveform D2 of the image signal shown in FIG. As shown in FIG. 9, it can be seen that the harmonic components are extremely small, and particularly, odd harmonics are hardly contained.

Returning to FIG. 3, the position calculation unit 31 is a Fourier transform unit 28 for the harmonics of each order and phase difference which are separated and extracted by the Fourier transform unit 28 in the case of normal observation.
And a storage unit for temporarily storing the harmonics of each order separated and extracted in the above. The position of the alignment mark AM for each harmonic of each order based on the harmonics of each order stored in the storage unit Ask for information. Here, the position calculation unit 31
Of the harmonics of each order, it is preferable to obtain position information for each of the odd harmonics. In this case, when determining the position information of the alignment mark AM, the position calculating section 31 preferably determines the position information by, for example, the following procedure.

First, of the detection results in the normal observation and the phase difference observation, the detection results containing a large number of odd-order harmonics are used. In this procedure, it is preferable to use the comparison result of the comparison unit 30 in FIG. Secondly, among the detection results selected in the first procedure, an odd-order harmonic having a higher order as much as possible and capable of obtaining a signal intensity sufficient for performing position measurement is selected. Finally, based on the detection result selected in the second procedure, the position information of the alignment mark AM is obtained by using a detection algorithm such as an edge detection method or a correlation method.

When the position calculation unit 31 obtains the position information, the above-described procedure may be changed in consideration of the shape of the alignment mark AM, for example, the duty of the mark and the conditions for forming the alignment mark. In addition, position information for each order is obtained from odd harmonics obtained from detection results in the case of normal observation, and each order information is obtained from odd harmonics obtained from detection results in the case of phase difference observation. Of the location information, and the average of the obtained location information,
The positional information of the alignment mark AM may be obtained from positional information excluding positional information of an order whose deviation from the average value is equal to or greater than a certain value.

The position information obtained by the position calculator 31 is output to the main control system 10. The main control system 10 drives the wafer stage 7 via the drive system 11 based on the position information of the alignment mark AM output from the position calculation unit 31, and exposes the shot area set on the wafer W to the light of the projection optical system PL. After adjusting the position, the exposure light EL is exposed on the reticle R, and the image of the pattern formed on the reticle R is transferred onto the wafer W to perform exposure processing.

Next, the operation of the position measuring device according to one embodiment of the present invention in the above-described configuration will be described. FIG. 10 is a flowchart showing the operation of the position measuring device according to one embodiment of the present invention. It should be noted that the flow shown in FIG. 10 shows only a procedure for measuring the position information of one alignment mark on the wafer W for easy understanding. Note that the flow shown in FIG.
It may be applied to all of the alignment marks AM formed on the wafer W in order. Of the alignment marks AM formed on the wafer W, several are selected and the position information is measured.
The present invention may be applied to so-called EGA measurement in which the position information of another alignment mark is calculated by statistical calculation.

Before the processing shown in FIG. 10 is started, the wafer W is introduced onto the wafer stage 7 of the exposure apparatus, and the reticle R used for exposing the wafer W is placed on the reticle stage 3. Then, the position of the reticle R is adjusted in advance. In the present embodiment, the case where alignment is performed by measuring the position of the alignment mark AM formed on the wafer W is described as an example. Therefore, measurement and alignment of the position information of the reticle R are described below. Although the details are omitted, the present embodiment can also be applied when measuring the position information of the reticle R.

Next, the main control system 10 drives the wafer stage 7 via the drive system 11 to move the alignment mark AM formed on the wafer W to a position corresponding to the detection area of the alignment sensor 12. (Step S1
0). When the movement of the alignment mark AM is completed, the switching control unit 29 in the position calculation unit 27 outputs a control signal to the actuator 18 so that normal observation can be performed (step S12). That is, the retarder turret 16 is rotated so that the optical axis of the illumination light IL is included in the opening OP1 provided in the retarder turret 16.

Next, the main control system 10 causes the light source 13 to emit illumination light. When the illumination light is emitted from the light source 13, the illumination light passes through the collimator lens 14, is reflected by the half mirror 15, passes through the opening OP1 formed in the retardation plate turret 16, is reflected by the mirror 19,
The light is converged by the objective lens 20 and illuminates the alignment mark AM with incident light. The reflected light generated by illuminating the alignment mark AM with the illumination light IL passes through the objective lens 20, the mirror 19, the opening OP1 of the phase difference plate turret 16, the half mirror 15, the mirror 21, and the index plate 23 via the lens system 22. Imaged on top. The image of the alignment mark AM of the wafer W and the index mark exposed to the reflected light form an image on the imaging surface of the imaging element 26 via the relay systems 24 and 25.

The image pickup element 26 converts the image of the alignment mark AM formed on the image pickup surface and the index mark into an electric signal, and outputs the electric signal to the position calculating unit 27 as an image signal.
When an image signal is input to the position calculation unit 27,
The Fourier transform unit 28 compares the harmonics obtained by performing the Fourier transform on the image signal with the comparison unit 30 and the position calculation unit 31.
Output to The comparison unit 30 and the position calculation unit 31 temporarily store the harmonic output from the Fourier transform unit 28 (Step S14). When a higher harmonic is output from the Fourier transform unit 28, a signal indicating that is output to the switching control unit 29. Upon receiving this signal, the switching control unit 29 outputs a control signal to the actuator 18 so that the phase difference observation can be performed (step S16). That is, the phase difference plate turret 16 is rotated so that the optical axis of the illumination light IL is included in the opening OP2 provided in the phase difference plate turret 16.

In a state where the phase difference observation can be performed, the illumination light emitted from the light source 13 passes through the collimator lens 14 and is reflected by the half mirror 15, and thereafter, the opening OP 2 formed in the phase difference plate turret 16. , And reflected by the mirror 19, condensed by the objective lens 20, and illuminate the alignment mark AM with incident light. The reflected light generated by illuminating the alignment mark AM with the illumination light IL reaches the objective lens 20, the mirror 19, and the opening OP2 of the phase difference plate turret 16. When the reflected light passes through the phase difference plate 17 provided in the opening OP2, the phase of the light not passing through the phase difference plate 17 is delayed by 90 degrees. The reflected light that has passed through the phase difference plate 17 passes through the half mirror 15, the mirror 21, and the lens system 22, and
3 is imaged. The image of the alignment mark AM of the wafer W and the index mark which are exposed to the reflected light correspond to the relay system 2
An image is formed on the image pickup surface of the image pickup element 26 via 4 and 25.

The image pickup device 26 converts the image of the alignment mark AM formed on the image pickup surface and the index mark into an electric signal and outputs the electric signal to the position calculation unit 27 as an image signal.
When an image signal is input to the position calculation unit 27,
The Fourier transform unit 28 compares the harmonics obtained by performing the Fourier transform on the image signal with the comparison unit 30 and the position calculation unit 31.
Output to The comparison unit 30 and the position calculation unit 31 temporarily store the harmonic output from the Fourier transform unit 28 (Step S18). By the above processing, the comparison unit 30
In addition, the harmonics obtained by Fourier-transforming the detection results in the case of normal observation and the case of phase difference observation are stored in the position calculation unit 31.

Next, the comparison unit 30 performs the Fourier transform of the detection result of the image sensor 26 obtained by performing normal observation and the harmonics of each order and the image sensor 2 obtained by performing phase difference observation.
Then, the detection result of No. 6 is compared with the harmonics of the respective orders obtained by performing the Fourier transform, and it is determined in which case the odd-order harmonics are more frequently included (step S20). Now, it is assumed that a detection result obtained by performing normal observation is a waveform indicated by a waveform D2 in FIG. That is, in the case of normal observation, a waveform close to a double mark is obtained as shown in FIG. 8, and harmonics of each order when this waveform is Fourier-transformed are odd harmonics as shown in FIG. Is almost not included.

It is assumed that the detection result obtained by performing the phase difference observation is as shown in FIG. FIG.
FIG. 9 is a diagram illustrating an example of a detection result obtained by performing phase difference observation. In FIG. 11, a curve denoted by reference symbol P3 schematically shows a cross-sectional shape of the alignment mark AM, and a curve denoted by reference symbol D3 is a waveform of the image signal.
Note that the curve denoted by reference numeral P3 in FIG. 11 is the same as the curve denoted by reference numeral P2 in FIG. As shown in the figure, by performing the phase difference observation, the waveform D3 of the image signal is measured as a substantially single mark. FIG. 12 shows a waveform D of the image signal shown in FIG.
FIG. 9 is a diagram showing harmonic components of each order obtained by performing Fourier transform on No. 3; As shown in FIG. 12, it can be seen that odd harmonics are included. In particular, primary, 3
Next and fifth harmonics are included.

The comparator 30 compares the odd-order harmonic component of the harmonics shown in FIG. 9 with the odd-order harmonic component of the harmonics shown in FIG. However, in the case of this example, since the one shown in FIG. 12 contains more odd-order harmonics, the comparison unit has more odd-order harmonics when phase difference observation is performed. A signal indicating that it is included is output to the position calculation unit 31. Position calculation unit 31
Calculates the position information of the alignment mark based on the signal output from the comparing unit 30 and using the temporarily stored harmonic of the harmonic when the phase difference observation is performed. Here, the position calculation unit 31 selects an odd-order harmonic having a higher order as much as possible and capable of obtaining a signal intensity sufficient for performing position measurement. For example, the fifth harmonic is selected. Then, based on the selected fifth harmonic, position information of the alignment mark AM is obtained using a detection algorithm such as an edge detection method or a correlation method (step S2).
2).

When the position calculation unit 31 obtains the position information, the above procedure may be changed in consideration of the shape of the alignment mark AM, for example, the duty of the mark, and the conditions for forming the alignment mark. In addition, position information for each order is obtained from odd harmonics obtained from detection results in the case of normal observation, and each order information is obtained from odd harmonics obtained from detection results in the case of phase difference observation. Of the location information, and the average of the obtained location information,
The positional information of the alignment mark AM may be obtained from positional information excluding positional information of an order whose deviation from the average value is equal to or greater than a certain value.

By the above processing, the alignment mark A
The process of measuring the position information of M ends, but the position information obtained by the position calculation unit 31 is output to the main control system 10. The main control system 10 drives the drive system 1 based on the position information of the alignment mark AM output from the position calculation unit 31.
After the wafer stage 7 is driven via 1 and the shot area set on the wafer W is adjusted to the exposure position of the projection optical system PL, the exposure light EL is exposed to the reticle R to form a pattern formed on the reticle R. Is transferred onto the wafer W to perform an exposure process.

As described above, the position measuring apparatus and the exposure apparatus according to one embodiment of the present invention have been described. However, the present invention is not limited to the above embodiment, and the design can be freely changed within the scope of the present invention. For example, the present invention is not limited to a step-and-scan type reduction projection type exposure apparatus.
The present invention can be applied to an exposure apparatus of an AND scan type, a mirror projection type, a proximity type, a contact type, and the like.

Further, not only an exposure apparatus used for manufacturing a semiconductor element and a liquid crystal display element, but also an exposure apparatus used for manufacturing a plasma display, a thin-film magnetic head, and an image pickup element (such as a CCD), and a reticle or a mask. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern onto a glass substrate, a silicon wafer, or the like in order to manufacture a substrate. That is, the present invention is applicable irrespective of the exposure method and application of the exposure apparatus.

In the above embodiment, the wafer W
The case where the position information of the alignment mark AM formed above is detected has been described as an example.
The present invention can also be applied to the case of detecting position information of a mark formed on a mark or a mark formed on a glass plate. Further, in the above embodiment, the case where the present invention is applied to an off-axis type alignment sensor has been described as an example. However, image processing is performed on an image signal captured by an image sensor to detect a mark position. The position detection of the present invention can be applied to all devices that perform the above-described operations.

The exposure apparatus (FIG. 1) according to the above-described embodiment of the present invention can precisely control the position of the wafer W at high speed, and can perform exposure with high exposure accuracy while improving throughput. As described above, the illumination optical system 1, the reticle stage 3, the base 4, and the mask alignment system including the driving device 5, the wafer holder 6, the wafer stage 7,
After the components shown in FIG. 1 such as the wafer alignment system including the movable mirror 8 and the laser interferometer 9 and the projection optical system PL are electrically, mechanically or optically connected and assembled,
It is manufactured by comprehensive adjustment (electrical adjustment, operation confirmation, etc.). It is desirable that the manufacture of the exposure apparatus be performed in a clean room in which the temperature, cleanliness, and the like are controlled.

Next, the manufacture of a device using the exposure apparatus and the exposure method according to one embodiment of the present invention will be described.
FIG. 13 is a flowchart of production of devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micromachines, etc.) using the exposure apparatus according to one embodiment of the present invention. As shown in FIG.
First, in step S20 (design step), a function design of a device (for example, a circuit design of a semiconductor device) is performed, and a pattern design for realizing the function is performed. Subsequently, in step S21 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step S22 (wafer manufacturing step), a wafer is manufactured using a material such as silicon. Next, in step S23 (wafer process step), actual circuits and the like are formed on the wafer by lithography using the mask and the wafer prepared in steps S20 to S22. Next, in step S24 (assembly step), step S23
Into chips using the wafer processed in the above. In this step S24, an assembly process (dicing,
Bonding), a packaging process (chip encapsulation), and the like. Finally, in step S25 (inspection step), inspections such as an operation confirmation test and a durability test of the device manufactured in step S25 are performed. After these steps, the device is completed and shipped.

The exposure apparatus of the present embodiment can be applied to a scanning exposure apparatus (US Pat. No. 5,473,410) for exposing a pattern of a mask by synchronously moving a mask and a substrate. Further, the exposure apparatus of the present embodiment can be applied to a proximity exposure apparatus that exposes a mask pattern by bringing a mask and a substrate into close contact without using a projection optical system. Further, the application of the exposure apparatus is not limited to an exposure apparatus for manufacturing a semiconductor. For example, an exposure apparatus for a liquid crystal that exposes a liquid crystal display element pattern to a square glass plate, or a thin film magnetic head is manufactured. Widely applicable to the exposure apparatus. The light source of the exposure apparatus of the present embodiment includes g-line (436 nm), i-line (365 nm), Kr
Not only an F excimer laser (248 nm), an ArF excimer laser (193 nm), and an F ₂ laser (157 nm) but also a charged particle beam such as an X-ray or an electron beam can be used. For example, when an electron beam is used, a thermionic emission type lanthanum hexaborite (LaB ₆ ) or tantalum (Ta) can be used as an electron gun.

The magnification of the projection optical system may be not only a reduction system but also any one of an equal magnification and an enlargement system. As the projection optical system,
When far ultraviolet rays such as an excimer laser are used, a material that transmits far ultraviolet rays such as quartz or fluorite is used as the glass material.
_{2 When} using a laser or X-ray, use a catadioptric or refracting optical system (use a reflective type mask). When using an electron beam, use an electron lens and deflector as the optical system. An electron optical system may be used. It goes without saying that the optical path through which the electron beam passes is in a vacuum state.

When a linear motor (see US Pat. No. 5,623,853 or US Pat. No. 5,528,118) is used for a wafer stage or a mask stage, either an air levitation type using an air bearing or a magnetic levitation type using Lorentz force or reactance force is used. May be used. The stage may be of a type that moves along a guide or a guideless type that does not have a guide. As the stage driving device, a planar motor that drives a stage by electromagnetic force with a magnet unit having two-dimensionally arranged magnets and an armature unit having two-dimensionally arranged coils opposed to each other may be used. In this case, one of the magnet unit and the armature unit may be connected to the stage, and the other of the magnet unit and the armature unit may be provided on the moving surface side of the stage.

The reaction force generated by the movement of the wafer stage is disclosed in JP-A-8-166475 (US Pat. Nos. 5,528,118).
As described in the above, a frame member may be used to mechanically escape to the floor (ground). The reaction force generated by the movement of the mask stage is mechanically released to the floor (ground) by using a frame member, as described in JP-A-8-330224 (US S / N 08 / 416,558). Is also good.

[0066]

As described above, according to the present invention, harmonics of each order diffracted by a mark are not separated by an optical means but converted into an image signal by an imaging means. Since the odd-order harmonics are extracted by the extracting means, even if the light source having a wide wavelength band is the light source of the illumination light, even if the light source having a wide wavelength band is the light source of the illumination light, the odd-order harmonics are not caused. Harmonics can be extracted. Also, since the position information of the mark is measured based on the extracted odd-order harmonics, the position information of the mark can be detected with high accuracy even when the mark is not formed as designed. There is. Further, according to the present invention, even when odd harmonics are hardly included due to lighting conditions or the like, odd harmonics can be included by changing the phase difference. There is an effect that measurement can be performed well even in a bad case.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of an exposure apparatus according to an embodiment of the present invention in which a position measuring device according to an embodiment of the present invention is used.

FIG. 2 is a cross-sectional view of the retarder turret 16;

FIG. 3 is a block diagram showing an internal configuration of a position calculation unit 27.

FIG. 4 is a diagram generalizing a periodic structure of an alignment mark AM.

FIG. 5 is a diagram illustrating an example of a waveform of an image signal obtained when the alignment mark AM is detected by the image sensor 26.

FIG. 6 is a diagram showing a waveform of an image signal measured under a certain illumination condition.

7 is a diagram showing harmonic components of each order obtained by performing a Fourier transform on the waveform D1 of the image signal shown in FIG. 6;

8 is a diagram illustrating a waveform of an image signal measured under illumination conditions different from those in FIG.

9 is a diagram illustrating harmonic components of each order obtained by performing a Fourier transform on the waveform D2 of the image signal illustrated in FIG. 8;

FIG. 10 is a flowchart showing an operation of the position measuring device according to one embodiment of the present invention.

FIG. 11 is a diagram illustrating an example of a detection result obtained by performing phase difference observation.

12 is a diagram illustrating harmonic components of each order obtained by performing a Fourier transform on the waveform D3 of the image signal illustrated in FIG. 11;

FIG. 13 is a flowchart when producing a device using the exposure apparatus according to the embodiment of the present invention.

FIG. 14 is a diagram for explaining a conventional technique for improving the position information detection accuracy of an alignment mark by using high-order diffracted light.

[Explanation of symbols]

 Reference Signs List 7 wafer stage 11 drive system 12 alignment sensor (imaging means) 13 light source (irradiating means) 14 collimator lens (irradiating means) 15 half mirror (irradiating means) 17 phase difference plate (phase difference generating means) 19 mirror (irradiating means) 20 Objective lens (irradiation unit) 26 Image sensor 27 Position calculation unit (extraction unit) 28 Fourier transform unit 29 Switching control unit (change unit) 30 Comparison unit (comparison unit) 31 Position calculation unit (calculation unit) W Wafer (object, substrate) ) AM alignment mark (mark) IL illumination light (detection beam)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 9/00 H01L 21/30 525W F-term (Reference) 2F065 AA03 AA07 BB27 CC20 FF48 FF55 GG02 HH03 JJ03 JJ26 LL12 LL35 PP12 PP23 QQ16 QQ25 QQ31 2H097 AB09 BA01 GB01 KA03 KA13 KA20 KA29 KA38 LA10 5F046 BA04 EB01 FA03 FA10 FB07 FB08 FB12 FC04

Claims (11)

[Claims] An irradiation unit configured to irradiate a mark formed on an object with a detection beam; an imaging unit configured to capture an image of the mark generated by the irradiation of the detection beam to generate an image signal; Extracting means for extracting odd-order harmonics based on the signal, based on the odd-order harmonics extracted by the extracting means,
A position measuring device comprising: a calculating means for obtaining position information of the mark. 2. The position measuring apparatus according to claim 1, wherein said extracting means includes a separating means for performing a Fourier transform on the image signal and separating harmonics included in the image signal for each order. . 3. The image processing apparatus according to claim 2, wherein the extracting unit further includes a changing unit that changes an imaging condition when the imaging unit performs imaging so as to obtain a phase difference image signal having a phase difference with respect to the image signal. The position measuring device according to claim 1 or 2, wherein 4. The image pickup means includes an image pickup element for converting an optical image of the mark into an image signal, and a phase difference generating means insertable into and removable from an image pickup optical path between the image pickup element and the object. The imaging conditions include a first condition for arranging the phase difference generating unit in the imaging optical path and a second condition for arranging the phase difference generating unit outside the imaging optical path, and the imaging unit performs the imaging under the first condition. 4. The position measuring device according to claim 3, wherein a phase difference image signal is generated. 5. The image pickup device includes an image pickup device that converts an optical image of the mark into an image signal, and the change unit displaces the object with respect to a focus position of the image pickup device. The position measuring device according to claim 3. 6. The extracting means further includes: comparing means for comparing odd-order harmonics included in the image signal with odd-order harmonics included in the phase difference image signal. The position information of the mark is obtained based on the odd-order harmonics extracted from the image signal containing a larger number of the odd-order harmonics. The position measuring device according to the item. 7. The method according to claim 1, wherein the arithmetic unit obtains position information of the mark for each of the extracted odd-order harmonics. The position measuring device according to claim 1. 8. The arithmetic unit, based on a predetermined condition related to the mark or the formation condition of the mark, obtained from a harmonic of a specific order among a plurality of pieces of mark position information calculated for each of the orders. 8. The position measuring apparatus according to claim 7, wherein mark position information is extracted, and the position of the mark is determined based on the extracted mark position information. 9. The arithmetic unit calculates an average value of the mark position information obtained for each of the orders, and uses an order other than the order corresponding to the mark position information whose deviation from the average value is equal to or more than a predetermined amount. 8. The position measuring device according to claim 7, wherein the position of the mark is obtained. 10. An exposure apparatus for transferring a predetermined pattern onto a substrate, wherein the mark is formed on the substrate by the position measurement apparatus according to claim 1. An exposure apparatus, comprising: an alignment device that aligns the predetermined pattern with the substrate based on position information, and exposes the aligned substrate with the predetermined pattern. 11. A method of irradiating a mark formed on a substrate with a detection beam, capturing an image of the mark generated by the irradiation of the detection beam to generate an image signal, and generating an odd number based on the image signal. Extracting a next harmonic, obtaining position information of the mark based on the extracted odd-order harmonic, aligning a predetermined pattern with the substrate based on the position information of the mark, And exposing the aligned substrate.