JP2001185474A - Alignment method, alignment device, substrate, mask, and exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method that increase the throughput of semiconductor manufacturing facility by speeding up an alignment mark detection. SOLUTION: In this alignment method, alignment marks (AMs) which consist of first mark elements (m11 to m15) and second mark elements (m21 to m26) which turn around and are offset arrayed in the direction of Y-axis that is perpendicular to X-axis on a substrate, are scanned electroptically in the array direction. The method comprises a step of detecting a first and second light intensity signals that vary in the array direction of the first and second mark elements, and a step of specifying information on the mark positions based on a third light intensity signal that can be obtained by adding two signals of the first and second light intensity signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, a liquid crystal display device, an image sensor, a thin film magnetic head, a micro device such as a micro machine, and a substrate and a mask used in a manufacturing process of a photomask (reticle).
And an alignment method and an alignment apparatus for performing alignment between the mask and a substrate to which the pattern is transferred, and an image of a pattern formed on the mask using the method or the apparatus is formed on a photosensitive substrate coated with a photoresist. The present invention relates to an exposure apparatus for transferring an image to a device, and a device manufacturing method using the alignment method.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, liquid crystal display devices, and the like, an image of a fine pattern formed on a photomask or reticle (hereinafter, these are collectively referred to as a mask) by using an exposure apparatus is used for forming a photoresist or the like. Projection exposure on a substrate such as a semiconductor wafer or a glass plate coated with a photosensitive agent is repeatedly performed. When performing projection exposure, it is necessary to precisely match the position of the substrate with the position of the pattern image formed on the mask to be projected. In order to perform this alignment, the exposure apparatus includes an alignment device. The alignment apparatus includes an alignment sensor that detects a position of an alignment mark formed on a substrate, and a control system that performs alignment of the substrate based on the position of the alignment mark detected by the alignment sensor.

Since the surface state (roughness) of a substrate to be measured changes during the manufacturing process of a semiconductor element, a liquid crystal display element, or the like, it is difficult to accurately detect the substrate position with a single alignment sensor. Generally, different sensors are used according to the surface condition of the substrate. The main alignment sensors are LSA (Laser StepAl).
ignment), FIA (Field Image Alignment), and LIA (Laser Interferometric Alignment). Hereinafter, outlines of these alignment sensors will be described.

An LSA type alignment sensor irradiates a laser beam onto an alignment mark formed on a substrate,
It is an alignment sensor that measures the position of an alignment mark by using diffracted and scattered light, and has been widely used for semiconductor wafers in various manufacturing processes. The FIA type alignment sensor is an alignment sensor that illuminates the alignment mark using a light source having a wide wavelength bandwidth such as a halogen lamp and performs image processing on an image of the obtained alignment mark to perform position measurement. It is effective for measuring asymmetric marks formed on a 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.

In recent years, among these alignment sensors, an FIA type alignment sensor is often provided in an exposure apparatus in order to improve throughput. As described above, the FIA type alignment sensor
Although it is necessary to perform image processing on the obtained image of the alignment mark, conventionally, it is general to obtain the position information of the alignment mark using a so-called edge detection method for detecting an edge position of the alignment mark. The alignment mark is formed by forming a plurality of rectangular marks, and illumination light is scattered or diffracted at the edge of each mark. As a result, of the reflected light, the amount of light reflected from the edge of the alignment mark is reduced. The edge detection method obtains position information of the alignment mark by utilizing the property that the amount of reflected light at the edge portion decreases when the alignment mark is illuminated.

The outline of the edge detection method will be described below. FIG. 14 is a diagram for explaining the edge detection method. FI
In the A-type alignment sensor, an image of the alignment mark obtained by illuminating the alignment mark with illumination light is converted into an image signal by an image sensor such as a CCD (Charge Coupled Device). As is well known, a CCD is a photoelectric conversion element in which many pixels are arranged, and an image signal output from the CCD is a discrete signal spatially sampled at a pixel pitch. In FIG. 14, circles indicate sampling values of the image signal output from the CCD, and a curve FC in the drawing indicates a curve obtained by fitting these sampling values with a predetermined function such as a quadratic function. It is. In the edge detection method, an edge position is detected using discrete values indicated by circles in the figure.

In a typical algorithm of the edge detection method, first, a maximum slope point is found. When the image signal shown in FIG. 14 is obtained, the maximum slope point is obtained for each of the slope LS and the slope RS. A CCD generally has pixels arranged in the same size, and the spatial sampling period is constant. Therefore, the difference ΔV between the values of adjacent sampling points in the direction indicated by the symbol V in FIG. Find the location where is maximal. In the example shown in FIG. 14, the maximum inclination point of the slope LS is the sampling point code P ₁ is attached, the maximum inclination point of the inclined RS is the sampling point code P ₂ is attached.

[0008] Next, from the obtained maximum slope point, the nearest point having the maximum value or the minimum value is found by climbing and descending. In other words, the difference between the sampling value at the maximum inclination point P ₁ or maximum inclination point sampling points reference numeral H ₁ is the direction or sign H ₂ attached are adjacent in a direction attached around the P _2, i.e. reference numeral A point at which the difference ΔV between the values in the direction to which V is attached is minimized.
When the points where the maximum value and the minimum value are obtained are obtained, the sampling values of these points are used as the maximum value and the minimum value of the slope. In the example shown in FIG. 14, the slope LS is the point having the maximum value is a point code P ₃ is attached,
That the minimum value is that the code P ₄ is attached. As for tilting the RS, the point having the maximum value code P ₅
And in that the attached, that the minimum value is that the code P ₄ is attached.

After obtaining the maximum value and the minimum value of each gradient, a slice level is set. The slice level is set, for example, with an intermediate value between the maximum value and the minimum value of each slope.
In the example shown in FIG. 14, the slice level of the slope LS is set to a straight line with a reference sign SL1, and the slice level of the slope RS is set to a straight line with a reference sign SL2. Then, a point E at which the slice level SL1 intersects the slope LS
₁ and the point _{E 2} the slice level SL2 intersects the inclined RS is set to the edge position. The above processing is performed over the entire image signal of the alignment mark, and the obtained edge position is averaged to detect the position of the alignment mark.

In addition to the edge detection method described above, a correlation method is known as a method for obtaining position information of an alignment mark. As a correlation method, for example, a template image signal is prepared in advance, and a normalized cross-correlation between the template image signal and the obtained image signal is calculated while shifting the relative position between the template image signal and the input image signal. There is a normalized cross-correlation method that calculates a correlation function depending on the correlation function and obtains a peak position of the correlation function. As another correlation method, there is an autocorrelation method used when the input image signal has symmetry. The autocorrelation method is a method in which an image signal is divided into two at a position considered to be near a symmetric point, and one position coordinate is inverted with respect to a target point to calculate a correlation.

[0011]

Incidentally, when measuring the position information of the alignment mark by using the edge detection method, it is desirable that the waveform of the image signal obtained from the CCD is constant. This is because if the waveform of the image signal changes each time the position information of the alignment mark is measured, the detection accuracy of the edge position is reduced. As a result, the measurement accuracy of the position information of the alignment mark is reduced, and in some cases, the position of the alignment mark is reduced. This is because the position information itself cannot be detected. Therefore, the conventional alignment sensor prepares a detection algorithm such as the above-described correlation method in addition to the edge detection method in advance, selects an optimal detection algorithm for each type of substrate, and measures the position information of the alignment mark. ing.

However, the surface condition of the alignment mark when it is measured differs for each alignment mark. FIG. 16 is a diagram illustrating an example of the surface state of the alignment mark at the time of measurement. The alignment mark 100 shown in FIG. 16 is a so-called line-and-space alignment mark in which rectangular mark elements 101 to 104 are arranged in a direction orthogonal to the longitudinal direction. When the position information of the alignment mark 100 is measured by the alignment sensor, a photoresist 105 is usually applied to the surface thereof.

In general, the photoresist 105 is applied to the surface of a substrate by a spin coater, and the thickness of the photoresist 105 is not uniformly applied from the surface to a predetermined thickness over the entire surface of the substrate. Therefore, as shown in FIG. 15, for example, place the mark elements 101 to 104 are not formed, that is, the portion of the space photoresist 105 is applied to a thickness _{T 2,} than the thickness _{T 2} are on the mark element 103 the photoresist 105 is considered to be applied in thicker T _1. The FIA type alignment sensor uses a light source having a wide wavelength band, such as a halogen lamp, so that the illumination light does not form interference fringes in the photoresist 105 as much as possible. No interference fringes are formed in the light source, but as a result of multiple reflection, the amount of reflected light as a whole decreases or increases.

When the amount of reflected light changes, the waveform of an image signal obtained by receiving the image of the alignment mark 100 by the CCD changes. FIG. 16 is a diagram showing a change in an image signal output from the CCD. The image signal obtained by detecting the alignment mark 100 shown in FIG. 16 by the alignment sensor is similar to the image signal marked with S100 in FIG.
In some cases, the strength is reduced at the portion where 2 is formed.
The intensity of the image signal S100 is reduced because the illumination light and the reflected light are reflected and interfere with each other in the resist 105 and are weakened at the position where the mark element 101 and the mark element 102 are formed. In addition, as in the case of an image signal denoted by reference symbol S110 in FIG. 16, there is a signal in which the intensity is reduced only at the edge portions of the marks 101 and 102.

The image signal S110 includes a mark 101,
The portion where the central portion of 102 is formed is almost flat,
Although the signal intensity is high because it has the same reflectance as the reflectance of the space portion, the illumination light is scattered and diffracted at the edges of the marks 101 and 102, and the intensity of the reflected light is reduced. Lower. In this specification, an image signal having a low signal intensity over the entire area where a mark element is formed, such as an image signal S100 in FIG. As in S110, an image signal having a low signal intensity only at an edge portion of a mark is referred to as a "double mark image signal".
Called. Similarly, when an image signal is converted into an intensity signal, it is referred to as a “single mark intensity signal” or a “double mark intensity signal”.

When the position information of the alignment mark 100 is measured by the alignment sensor, the image signal of the single mark or the image signal of the double mark is detected according to the state of the substrate surface. In the case of using the edge detection method, when a single mark image signal or a double mark image signal having the shape shown in FIG. 16 is obtained, the edge position of each mark can be detected from the slice level without any problem. As a result, the alignment mark 10 is accurately formed.
It is considered that 0 position information can be measured. However, the image signal of the alignment mark 100 is
Smooth image signals such as the single mark image signal and the double mark image signal shown in FIG. 16 are rarely obtained, and an image signal in which these are mixed is often detected. In such a case, the position information of the alignment mark 100 cannot be accurately measured by the edge detection method.
Even the position information cannot be measured.

On the other hand, when using the normalized cross-correlation method among the above-mentioned correlation methods, for example, a single mark image signal is prepared in advance as a template image signal, and a correlation function with the obtained image signal is calculated. I do. In this case, if the obtained image signal is a single mark image signal, it is useful for measuring the position information of the alignment mark 100. However, if the obtained image signal is a double mark image signal, the measurement accuracy is high. In some cases, it is impossible to even measure the position information of the alignment mark. It is conceivable that a single mark image signal and a double mark image signal are prepared in advance as template image signals, and one of the template image signals is used according to the obtained image signal. The autocorrelation method described above is useful when the symmetry of the image signal is high.

When measuring the position information of the alignment mark 100, whether the single mark image signal or the double mark image signal is obtained depends on the thickness of the photoresist 105, the uniformity of the photoresist 105,
It depends on the lighting conditions and the like, and it is necessary to determine which of the detection algorithms for measuring the position information of the alignment mark in accordance with the obtained image signal. However, this process is extremely redundant, and must be performed for each alignment mark, which may cause a decrease in throughput. Further, the selected detection algorithm may not always be appropriate for the detected image signal, and it may not be possible to detect a mark position with high accuracy.

The present invention has been made in view of such problems of the conventional technology, and has as its object to increase the speed and accuracy of alignment processing.

[0020]

Hereinafter, in the examples shown in this section, for ease of understanding, each constituent element of the present invention will be described with typical reference numerals shown in the drawings of the embodiments. The configuration of the present invention or each component requirement is not limited to those restricted by these reference numerals.

In order to solve the above-mentioned problems, an alignment method according to the present invention is an alignment method for aligning a posture of a substrate (W) with a predetermined reference, wherein the alignment is orthogonal to an arrangement direction (X-axis direction) on the substrate. Marks (AM) including first and second mark elements (m _{11 to} m ₁₅ , m _{21 to} m ₂₆ ) arranged so as to be inverted with respect to each other while being displaced in a direction (Y-axis direction). Detecting first and second light intensity signals that change in intensity with respect to the arrangement direction of the first and second mark elements by scanning optically in a direction (S12 to S14); Specifying the position of the mark based on a third light intensity signal obtained by adding the signal and the second light intensity signal (S1)
6).

According to the present invention, the first and second mark elements arranged so as to be inverted with respect to each other while being displaced in the direction orthogonal to the arrangement direction are electro-optically scanned to perform the first mark element.
Since the light intensity signal and the second light intensity signal are obtained, the first light intensity signal and the second light intensity signal are added to calculate the third light intensity signal, and the position of the mark is calculated. Even if the first light intensity signal and the second light intensity signal are single mark or double mark intensity signals, the obtained third light intensity signal is always a double mark intensity signal, so it is necessary to select a detection algorithm. Therefore, the position information of the alignment mark can always be stably detected, and as a result, the throughput can be improved.

Although not particularly limited, the substrate includes a photosensitive substrate (W) and a mask (2). In addition, the mark (AM) includes a first direction mark (am1, am2) in which the first and second mark elements are arranged in a first direction, and the first and second mark elements are orthogonal to the first direction. Second
Second direction marks (am11, am12) arranged in the direction
It is preferable to include Further, the mark (AM) may be in a check form. Further, the first and second mark elements may be formed regularly at a predetermined pitch, or the first and second mark elements may be formed such that their arrangement duties are random. .

[0024] The alignment apparatus of the present invention is an alignment apparatus for adjusting the attitude of the substrate (W) to a predetermined reference, the attitude adjusting apparatus (8, 9, 12) for adjusting the attitude of the substrate. A first mark element and a second mark element arranged so as to be mutually inverted in a state of being displaced in a direction (Y-axis direction) orthogonal to an arrangement direction (X-axis direction) on the substrate (m _{11 to} m ₁₅ , m _{21 to} m ₂₆ ) The mark (AM) is electro-optically scanned in the arrangement direction to detect first and second light intensity signals whose intensity changes in the arrangement direction of the first and second mark elements. Detection device (1
4, 18) and a third light intensity signal obtained by adding the first light intensity signal and the second light intensity signal, so that the posture adjusting device (8,
And a control device (13) for controlling (9, 12). According to the present invention, the same effect as the above-described alignment method can be obtained.

The exposure apparatus according to the present invention further comprises a mask (2)
In an exposure apparatus for projecting the image of the pattern on the photosensitive substrate (W), a posture adjusting device (3,5) for adjusting the posture of at least one of the photosensitive substrate (W) and the mask (2).
8, 9, 12) and first and second mark elements (m ₁₁ to m ₁₁₎ arranged so as to be mutually inverted while being displaced in a direction orthogonal to the arrangement direction (X-axis direction) on the photosensitive substrate.
_{m 15, m 21 ~m 2 6} ) by electro-optically scanned in the arrangement direction of the mark (AM) comprising a first and a second to change in intensity with respect to the arrangement direction of the first and second mark element Detecting devices (14, 18) for detecting a light intensity signal;
Based on a third light intensity signal obtained by adding the first light intensity signal and the second light intensity signal, the posture adjustment device (3, 8,...) Adjusts the postures of the substrate and the mask to each other.
(9, 12). According to the present invention, the same effects as those of the above-described alignment method and alignment apparatus can be obtained.

Further, the substrate (W) of the present invention is arranged in a direction (Y-axis direction, X-axis direction, X-axis direction, Y-axis direction) orthogonal to the arrangement direction (X-axis direction, Y-axis direction).
The first and second mark elements (m _{11 to} m ₁₅ , m ₁₅ ) arranged to be inverted from each other while being displaced in the axial direction).
Is characterized in _{that 21 ~m 26, m 31 ~m 35} , m 41 ~m 46) alignment marks comprising (AM) is formed.

Further, the mask (2) of the present invention can be arranged in a direction (Y-axis direction, X-axis direction, X-axis direction, Y-axis direction) orthogonal to the arrangement direction (X-axis direction, Y-axis direction).
An alignment mark including first and second mark elements arranged so as to be inverted with respect to each other while being displaced in the (axial direction) is formed.

Further, the mask of the present invention is arranged in the arrangement direction (X-axis).
Direction (Y-axis direction)
Are arranged in such a way that they are reversed
Mark pattern including first and second mark element patterns
Is formed. According to the invention
If so, the arrangement direction (X-axis direction, Y-axis direction)
Position in the direction (Y-axis direction, X-axis direction) orthogonal to
First and second arrays arranged to be inverted from each other in a shifted state
And the second mark element (m₁₁~ M_Fifteen, M₂₁~ M ₂₆,
m₃₁~ M₃₅, M₄₁~ M₄₆) Including alignment
Marks (AM) can be formed.

Further, in the device manufacturing method of the present invention, the first and second mark elements (m _{11 to} m ₁₅ , m _{21 to} m
₂₆ ) A photoresist is applied onto the substrate (W) on which the mark (AM) including the mask (2) is formed, and the mask is aligned while performing alignment between the mask (2) and the substrate using the alignment method according to claim 1. And transferring the pattern to the photoresist.

[0030]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an exposure apparatus according to an embodiment of the present invention. This exposure apparatus is a step-and-repeat type exposure apparatus including an off-axis type alignment sensor.

In this embodiment, the position information of the alignment mark formed on the wafer W is measured using the alignment sensor, and the position of the wafer W is measured based on the measured position information.
The case where the position is adjusted will be described, but the case where the position is adjusted by measuring the position information of the mask can be similarly applied.

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, when a control signal for instructing emission of exposure light is output from a main control system 13, which will be described later, an illumination optical system 1 emits exposure light EL having substantially uniform illuminance to cause the mask 2 to emit light. Irradiate. The optical axis of the exposure light EL is set parallel to the Z-axis direction. Examples of the exposure light EL include g-line (436 nm), i-line (365 nm),
KrF excimer laser (248 nm), ArF excimer laser (193nm), _{F 2} laser (157 nm) is used.

The mask 2 has a fine pattern to be transferred onto a wafer (substrate) W coated with a photoresist, and is held on a mask holder 3. Mask holder 3
Is supported on the base 4 so that it can move and minutely rotate in the XY plane. A main control system 13 that controls the operation of the entire apparatus controls the operation of the mask stage 3 via the driving device 5 on the base 4 to set the position of the mask 2.

When the exposure light EL is emitted from the illumination optical system 1, the pattern image of the mask 2 is projected onto each shot area set on the wafer W via the projection optical system 6. The projection optical system 6 has optical elements such as a plurality of lenses,
The glass material of the optical element is selected from optical materials such as quartz and fluorite according to the wavelength of the exposure light EL. The wafer W is mounted on a Z stage 8 via a wafer holder 7.
The Z stage 8 is a stage for finely adjusting the position of the wafer W in the Z-axis direction. The Z stage 8 is mounted on the XY stage 9. The XY stage 9 is a stage that moves the wafer W within the XY plane. Although not shown, a stage for slightly rotating the wafer W in the XY plane and a stage for changing the angle with respect to the Z axis to adjust the inclination of the wafer W with respect to the XY plane may be provided.

An L-shaped movable mirror 10 is attached to one end of the upper surface of the wafer holder 7, and a laser interferometer 11 is disposed at a position facing the mirror surface of the movable mirror 10. Although the illustration is simplified in FIG. 1, the movable mirror 10 is constituted by a plane mirror having a mirror surface perpendicular to the X axis and a plane mirror having a mirror surface perpendicular to the Y axis. In addition, the laser interferometer 11 irradiates the movable mirror 11 with a laser beam along the X-axis.
A laser interferometer for the X axis and a laser interferometer for the Y axis for irradiating the movable mirror 11 with a laser beam along the Y axis, one laser interferometer for the X axis and one for the Y axis. The X and Y coordinates of the wafer stage 7 are measured by the laser interferometer.

The rotation angle of the wafer holder 7 in the XY plane is measured based on the difference between the measured values of the two X-axis laser interferometers. The information of the X coordinate, the Y coordinate, and the rotation angle measured by the laser interferometer 11
Supplied to These pieces of information are output from the stage drive system 12 to the main control system 13 as position information. Main control system 1
Reference numeral 3 controls the positioning operation of the wafer holder 7 via the stage drive system 12 while monitoring the supplied position information. Although not shown in FIG. 1, the mask holder 3 is also provided with a movable mirror and a laser interferometer provided on the wafer holder 7, and information such as the XYZ position of the mask holder 3 is mainly controlled. Input to the system 13.

An off-axis alignment sensor 14 is provided beside the projection optical system 6. The alignment sensor 14 forms a part of the alignment apparatus according to the embodiment of the present invention provided in the exposure apparatus according to the embodiment of the present invention, and is an FIA (Field Image Alignm).
ent) method.
Irradiation light for illuminating the wafer W from the halogen lamp 15 via the optical fiber 16 is incident on the alignment sensor 14. Here, the halogen lamp 15 is used as the light source of the illumination light because the wavelength range of the light emitted from the halogen lamp 15 is 500 to 800 nm, which is a wavelength range in which the photoresist applied to the upper surface of the wafer W is not exposed. This is because the influence of the wavelength characteristic of the reflectance on the surface of the wafer W can be reduced.

The illumination light emitted from the alignment sensor 14 is reflected by the prism mirror 17 and irradiates the upper surface of the wafer W. The alignment sensor 14 takes in the reflected light on the upper surface of the wafer W via the prism mirror 17, converts the detection result into an electric signal, and outputs the electric signal to the alignment signal processing system 18. The alignment signal processing system 18
Based on the detection result output from the alignment sensor 14, the position shift (defocus amount) of the street line SL formed on the wafer W with respect to the focal position of the alignment sensor 14 and the position of the alignment mark AM in the XY plane are obtained. These are output to the main control system 13 as wafer position information.

The main control system 13 controls the overall operation of the exposure apparatus based on the position information output from the stage drive system 12 and the wafer position information output from the alignment signal processing system 18. More specifically, the main control system 13
A drive control signal is output to the drive device 12 based on the wafer position information output from the alignment signal processing system 18. The drive device 12 determines the X based on the drive control signal.
The Y stage 9 and the Z stage 8 are driven by stepping.

At this time, the main control system 13 first
A drive control signal is output to the drive device 12 so that the position of the reference mark formed on the drive device 12 is detected by the position detection sensor. When the driving device 12 drives the XY stage 9, the detection results of the alignment sensor 14 and the position detection sensor are output to the alignment signal processing system 18. From this detection result, for example, a baseline amount that is a deviation amount between the detection center of the position detection sensor and the center of the projected image of the mask 2 (the optical axis AX of the projection optical system 6) is measured. Then, the X coordinate and the Y coordinate of the wafer W are controlled based on a value obtained by adding the above-described baseline amount to the position of the alignment mark AM measured by the position detection sensor, so that each shot area can be accurately determined. To match the exposure position.

In this embodiment, in order to improve the detection accuracy of the position of the alignment mark AM, the position of the street line SL formed on the wafer W is determined by the alignment sensor 1.
Control for adjusting to the focal position of No. 4 is performed. That is, when measuring the position of the alignment mark AM in the XY plane, the main control system 13 first controls the stage drive system 12 so that the alignment mark AM falls within the detection range of the position detection sensor. The stage driving system 12 is controlled so that the position of the street line SL formed in W in the Z-axis direction is focused on the focal position of the alignment sensor 14. After detecting the position of the alignment mark AM and performing control to accurately adjust the shot area to be exposed to the exposure position, the main control system 13 outputs a control signal for causing the illumination optical system 1 to emit the exposure light EL. .

Next, the alignment sensor 1 provided in the alignment apparatus employed in the exposure apparatus of this embodiment
4 will be described in detail with reference to FIG. In FIG. 2, the same members as those shown in FIG. 1 are denoted by the same reference numerals. As shown in FIG. 2, the illumination light I having a wavelength range of 500 to 800 nm from the halogen lamp 15 shown in FIG.
L1 is derived.

The illumination light IL 1 is incident on the field dividing aperture plate 21 via the condenser lens 20. The field splitting diaphragm plate 21 defines the shape of the image of the illumination light IL1 that irradiates the wafer W. FIG. 3A is a diagram illustrating an example of the field division stop plate 21. As shown in the figure, the field dividing aperture plate 21 has a mark illumination aperture 21a having a wide rectangular opening at the center thereof, and a mark illumination aperture 2a.
Focus detection slits 21b and 21c formed by a pair of narrow rectangular openings arranged so as to sandwich 1a are formed. The illumination light IL1 becomes illumination light IL2 composed of a first light beam for mark illumination for illuminating the alignment mark area on the substrate W by the field dividing aperture plate 21, and a second light beam for focus position detection prior to alignment.

After passing through the lens system 22, the illumination light IL2 is reflected by the half mirrors 23 and 24 and is reflected by the objective lens 25.
And is emitted from the alignment sensor 14. When the illumination light IL2 is emitted from the alignment sensor 14, it is reflected by the prism mirror 17 and illuminates the vicinity of the alignment mark AM formed on the wafer W. Here, the alignment mark AM will be described in detail.

FIG. 4 is a view showing an example of the alignment mark AM, and FIG. 5 is a sectional view taken along the line AA and the line BB in FIG. In FIG. 5, a line denoted by reference numeral PF1 indicates a cross section taken along line AA in FIG. 4, and a line denoted by reference numeral PF2 indicates a cross section taken along line BB in FIG. 4.

As shown in FIGS. 4 and 5, the alignment mark AM is a rectangular mark element m ₁₁ , m ₁₂ , m ₁₃ , m ₁₄ , whose longitudinal direction is set in the Y-axis direction in the figure.
The m _{1 5} and the first mark am1 arranged in X-axis direction, the mark elements _m 11 _{~m 15} similar mark shape elements _{m 21, m 22, m 23} , m 24, m 25, m 26,
The longitudinal direction is set in the Y-axis direction, and each of the second marks am2 is arranged in the X-axis direction. 1st mark am1
The positional relationship between the second mark am2 includes a respective mark elements _m 11 _{~m 15} of the first mark am1 in the Y-axis direction second
And the respective mark elements _m 21 _{~m 26} is arranged at a position shifted state so as not to overlap the mark am2. The alignment marks AM shown in FIGS. 4 and 5 are alignment marks for obtaining position information in the X-axis direction in the figures.

Referring again to FIG. The wafer W is arranged so that the region where the alignment mark AM is formed is substantially conjugate (image-forming relationship) with the field division stop plate 21 with respect to the combined system of the lens system 22 and the objective lens 25. The reflected light of the illumination light IL2 is reflected by the half mirror 24 via the prism mirror 17 and the objective lens 25, and then passes through the half mirror 23. Thereafter, the light reaches the beam splitter 27 via the lens system 26, and the reflected light is branched in two directions. The first split light transmitted through the beam splitter 27 forms an image of the alignment mark AM on the index plate 28. Then, this image and light from the index mark on the index plate 28 are incident on an image sensor 29 formed of a two-dimensional CCD, and the image of the mark AM and the index mark is formed on the light receiving surface of the image sensor 29.

On the other hand, the second split light reflected by the beam splitter 27 enters the light shielding plate 30. FIG. 3B is a diagram illustrating an example of the light shielding plate 30. The light-shielding plate 30 shown in FIG. 3B shields light incident on a rectangular area denoted by reference numeral 30a, and transmits light incident on an area 30b other than the rectangular area 30a. Therefore, the light shielding plate 30 is the first
Is blocked, and the branched light corresponding to the second light flux is transmitted. The branched light transmitted through the light shielding plate 30 is
In a state where the telecentricity is broken by the pupil division mirror 31, the light enters the line sensor 32 formed of a one-dimensional CCD, and the images of the focus detection slits 21b and 21c are formed on the light receiving surface of the line sensor 32.

Here, since the telecentricity is ensured between the substrate W and the image pickup device 29, when the substrate W is displaced in a direction parallel to the optical axis of the illumination light and the reflected light, the light receiving surface of the image pickup device 29 Alignment mark AM imaged on top
Is defocused without changing the position on the light receiving surface of the image sensor 29.

On the other hand, since the reflected light incident on the line sensor 32 has lost its telecentricity as described above, when the substrate W is displaced in a direction parallel to the optical axis of the illumination light and the reflected light. The images of the focus detection slits 21b and 21c formed on the light receiving surface of the line sensor 32 are displaced in a direction intersecting the optical axis of the branched light. By utilizing such properties and measuring the amount of deviation of the image on the line sensor 32 from the reference position, the position (focal position) of the illumination light and reflected light of the substrate W in the optical axis direction is detected. The detection result of the image sensor 29 and the detection result of the line sensor 32 are output to the alignment signal processing system 18.

Next, the principle for achieving the object of the present invention when the alignment mark AM shown in FIGS. 4 and 5 is used will be described. As described with reference to FIG. 16, the detection result output from the image sensor 29 depending on the thickness of the resist applied on the alignment mark and the illumination conditions, that is, the image signal is a single mark or double mark image signal. I will. In this embodiment,
By using the alignment mark AM shown in FIGS. 4 and 5 to always obtain the image signal of the double mark, there is no need to select a detection algorithm, and the position information of the alignment mark is always detected stably. As a result, the throughput is improved.

FIGS. 6, 7 and 8 are diagrams for explaining the principle of always obtaining an image signal of a double mark by using the alignment mark AM shown in FIGS. 4 and 5. FIG.
6, 7, and 8, the horizontal axis is the alignment mark AM.
And the vertical axis represents the intensity of the image signal. In addition,
The vertical and horizontal scales shown in FIGS. 6 to 8 are the same intervals between the drawings. In these figures,
For example the image signal of the first mark am1 in mark elements m ₁₁ of the alignment mark AM shown in FIG. 5, the image signal of the space portion between the mark elements m ₂₁ and mark elements m ₂₂ in the second mark am2 3 shows the detection result.

The position x in these figures
₁Is the mark element m₁₁And mark element m₂₁One of
And the position x₂Is
Element m ₁₁Position corresponding to the other edge position of
And the mark element m₂₂To one edge position
It is the position to hit. That is, the position x₁And position x₂When
Mark element m between₁₁Is formed and the position x₁Left of
Side, ie position x₀Mark element m on the side₂₁Formed
Position x₂To the right of position x₃Need mark on side
Element m₂₂Are formed.

FIG. 6 shows a mark element m₁₁, M₂₁, M
₂₂When the ratio of the reflectance of the space and the space is 1: 0.9
If the mark element m₁₁, M₂₁, M₂₂Is a wafer
Image detected when formed of the same material as W
2 shows an intensity signal obtained from the signal. Smell in Figure 6
And I₁₁Is the mark element m₁₁From the image signal
And the intensity signal₁₂Is the mark element
m₂₁, M₂₂The intensity signal obtained from the image signal
ing. Mark element m₁₁, M₂₁, M₂₂Is a space
Portion has a higher reflectivity than the₁₁
Is the position x₁And position x₂ Is a strong signal between
The intensity signal I₁₂Is the position x₀And position x₁Between
And position x₂And position x₃With a strong signal between
is there. As can be seen, the resulting intensity signal I₁₁,
I₁₂Is partially a double mark, but overall
Is an intensity signal of a single mark.

In this embodiment, the strength shown in FIG.
Signal I₁₁And intensity signal I₁₂And then add these
Average. That is, the intensity signal I₁₁And intensity signal I₁₂When
Is performed, and the result obtained by performing the addition is divided by 2.
In FIG.₁₃Is the intensity signal I ₁₁And intensity signal I₁₂With
This is an intensity signal obtained by performing averaging. Illustrated
Thus, the intensity signal I₁₃Is the edge position x₁In
Intensity and edge position x ₂Signal with low intensity at
Is converted to a double mark intensity signal.
Become.

FIG. 7 shows mark elements m ₁₁ ,
The ratio of the reflectance of m _{21, m 22} and the space portion is 1:
0.8, ie, mark elements m ₁₁ , m ₂₁ , m
₂₂ shows an intensity signal obtained from an image signal detected when the reference numeral ₂₂ is formed of a material having a relatively higher reflectance than the wafer W. For example, this is a case where mark elements m ₁₁ , m ₂₁ , and m ₂₂ are formed on the wafer W with aluminum. In FIG. _{7, I 21} shows the intensity signals obtained from the image signal of the mark elements _{m 11, I 22} shows the intensity signals obtained from the image signal of the mark elements _{m 21, m 22.}

As in FIG. 6, the mark elements m ₁₁ ,
Since m ₂₁ and m ₂₂ have a higher reflectivity than the space portion, the intensity signal I ₂₁ indicates the position x ₁ and the position x ₂
A high strength signal with the intensity signal I ₂₂ is between position x ₀ and the position x _1, and positions x ₂ and the position x
₃ is a signal having a high intensity. In the case of FIG. 7 as well, the obtained intensity signals I ₂₁ and I ₂₂ are entirely single-mark intensity signals. _{I 23} in FIG. 7 intensity signal I
Averaging between ₂₁ and intensity signal I ₂₂ is the intensity signal obtained by performing. When compared to the intensity signals I ₁₃ shown in FIG. 6, although the value of the intensity of the vertical axis is different, the position of the minimum value of the two locations indicating the edge position is the same position.

FIG. 8 shows a mark element m₁₁,
m₂₁, M₂₂Figure 6 shows the ratio of the reflectance of the
1: 0.9 as in the case of
₁₁, M₂₁, M₂₂Almost twice the height of Fig. 6
The strength obtained from the image signal detected when set
The degree signal is shown. In FIG. 8, I₃₁The mar
Element m₁₁Shows the intensity signal obtained from the image signal
Yes, I₃₂Is the mark element m ₂₁, M₂₂Image signal
5 shows an intensity signal obtained from the above.

The intensity signals I ₃₁ and I ₃₂ shown in FIG.
Unlike FIG. 6 and FIG. 7, the intensity signal of the double mark is obtained. Since the heights of the mark elements m ₁₁ , m ₂₁ , and m ₂₂ are high, scattering and diffraction at the edge portion are large, and the intensity at the edge portion is as shown in FIG. 7 is lower than the result shown in FIG. _{I 33} in FIG. 8 is the intensity signal I
Averaging between ₃₁ and intensity signal I ₃₂ is the intensity signal obtained by performing. As shown in FIG. 8, intensity signal I ₃₃ obtained by performing averaging of the intensity signal I ₃₁ and the intensity signal I ₃₂ is the intensity signal of the double mark is a signal of double mark.

[0061] Thus, as shown in FIG. 6 to FIG. 8, the mark elements m ₁₁ intensity obtained from the image signals signal and a mark element m _21, the intensity signal strength signal obtained from the image signals of the single mark of m ₂₂ of Or the intensity signal of the double mark, the intensity signal obtained by performing the averaging process of these intensity signals is always the intensity signal of the double mark. Therefore, there is no need to select a detection algorithm, and the position information of the alignment mark can always be stably detected, and as a result, the throughput can be improved. Also, as shown in FIGS.
Even if the averaging process is performed, the edge position hardly changes, so that the detection accuracy is hardly affected. The above processing is performed by the alignment signal processing system 18 in FIG.

Next, the operation of position detection and exposure using the alignment sensor 14 of the exposure apparatus of the present embodiment will be described. FIG. 9 is a flowchart showing the position detection operation of the exposure apparatus. Note that the flow shown in FIG. 9 shows a procedure for forming the alignment mark on the wafer W and then measuring the position information of the alignment mark AM on the entire wafer W. In FIG. 9, for ease of understanding, the position measurement is performed on all the alignment marks AM formed on the wafer W, but the positions of several alignment marks AM formed on the wafer W are measured. The present invention can also be applied to so-called EGA measurement in which the position information of another alignment mark is calculated by statistical calculation.

When the process starts, first, a process of forming an alignment mark AM on the wafer W is performed (step S10). In this process, for example, a photoresist is applied to the upper surface of the wafer W, and an exposure process is performed using a mask on which an alignment mark pattern shown in FIG. 4 is formed. Then, the photoresist is developed and the wafer W is etched. By doing so, an alignment mark AM is formed.
Note that the method of forming the alignment mark AM is not limited to this method, and any method may be used as long as the alignment mark AM shown in FIGS. 4 and 5 can be formed.

When the alignment mark AM is formed on the wafer W, the wafer W is introduced onto the wafer stage 7 of the exposure apparatus, and is replaced with a mask used when exposing the wafer W as the mask 2. The mask 2 is aligned. In the present embodiment,
Although the case where the alignment is performed by measuring the position of the alignment mark AM formed on the wafer W is described as an example, the measurement and alignment of the positional information of the mask 2 are omitted in detail, though. 4, the alignment mark shown in FIG. 4 is also formed on the mask 2, and an alignment sensor for measuring the position information of the alignment mark is provided, and the alignment is performed by measuring the position information as in the case of the wafer W. preferable.

Next, the main control system 13 includes the stage drive system 1
The XY stage 9 is driven so that the alignment mark AM on the wafer W moves to a position corresponding to the position within the detection area of the alignment sensor 14 via the interface 2. When the movement of the alignment mark AM is completed, the main control system 13 outputs a control signal to the halogen lamp 15 to emit the illumination light IL1. When the illumination light IL1 is emitted, the illumination light IL1 is introduced into the alignment sensor 14 via the optical fiber 16, passes through the condenser lens 20, is shaped by the field division stop plate 21, and becomes the illumination light IL2. Illumination light I
L2 is transmitted through the lens system 22 to form the half mirrors 23 and 24.
After passing through the objective lens 25, the light is reflected by the prism mirror 17 and irradiated onto the wafer W.

The reflected light of the illumination light IL2 is the prism mirror 1
7, the first split light transmitted through the objective lens 25, the half mirrors 24 and 23, and the lens system 26 in order, and transmitted through the beam splitter 27 is aligned on the index plate 28 by an alignment mark. An image of AM is formed. Then, this image and light from the index mark on the index plate 28 are incident on an image sensor 29 composed of a two-dimensional CCD, and the alignment mark AM is formed on the light receiving surface of the image sensor 29.
And the image of the index mark is formed.

FIG. 10 is a diagram showing a state in which an image Im of the alignment mark AM is formed on the imaging surface 40 of the imaging element 29. Now, the mark elements of the alignment mark AM _m 11 _{~m 15} and mark elements _m 21 ~m
_{Since 26} is formed of a material having a higher reflectivity than the space portion, the images im _{11 to} im ₁₅ and im _{15 of} the mark elements m _{11 to} m ₁₅ and the mark elements m _{21 to} m ₂₆ are formed.
It is assumed that each of _{21 to} im ₂₅ forms an image brighter than the surroundings. In the drawings, the image i mark elements _m 21 _{~m 26}
and hatched _{m 11 ~im 15, im 21 ~im} 25. The imaging element 29 scans the optical image formed on the imaging surface 40 and performs photoelectric conversion, and it is assumed that the scanning direction is set in the direction shown in FIG. Alignment mark AM imaged on image plane 40 by image sensor 29
Are scanned, sequentially converted into image signals, and output to the alignment signal processing system 18 (step S12).

The alignment signal processing system 18 temporarily stores the image signal output from the alignment sensor 14 in a memory. The alignment signal processing system 18 converts the image signal stored in the memory into an intensity signal and stores it in the memory (step S13). Note that the method of storing in the memory stores the intensity signal and the position of the imaging surface 40 shown in FIG. 10 in association with each other.

Next, the alignment signal processing system 18 performs the following operations on the imaging surface 40 shown in FIG.
A process of adding and averaging the intensity signals of the three lines marked with 3 in the non-measurement direction to detect the first light intensity signal and the intensity signals of the three lines marked L21 to L23 are performed. Are added in the non-measurement direction, averaged, and detected as the second light intensity signal (step S1).
4).

Here, the reference numerals L11 to L13
The reason why the averaging process is performed on the intensity signals for the lines and the intensity signals for the three lines to which the symbols L21 to L23 are attached is to reduce the variation in detection for each line and improve the measurement accuracy. FIG. 11 is a diagram showing a light intensity signal obtained when an image of the alignment mark AM is formed in the state shown in FIG. In FIG. 11, (a) is the first light intensity signal, and (b) is the second light intensity signal.

When the first light intensity signal and the second light intensity signal are detected, the alignment signal processing system 18 then performs an averaging process on the first light intensity signal and the second light intensity signal, The three light intensity signals are calculated (Step S15).
When the first light intensity signal is as shown in FIG. 11A and the second light intensity signal is as shown in FIG.
The calculated third light intensity signal is as shown in FIG.

The alignment signal processing system 18 is configured as shown in FIG.
Waveform processing is performed on the third light intensity signal shown in (c) to detect the position information of the alignment mark AM (step S16). In detecting the position information, there is no inconvenience to use any of the above-described edge detection method and correlation method, and any of them may be used. However, in order to improve the measurement accuracy of the position information, the edge detection method and the correlation method are used. The position information may be measured using both of them, and the measurement results may be averaged to improve the detection accuracy. This method is very preferable from the viewpoint of improving accuracy, because the amount of judgment when performing position measurement is increased.

When the alignment signal processing system 18 calculates the position information of the alignment mark AM, the alignment signal processing system 18 outputs to the main control system 13 as wafer position information. The main control system 13 performs correction by adding the above-described baseline amount to the input wafer position information.

The main control system 13 includes the stage drive system 1
2, the center of each shot area and the optical axis A of the projection optical system 6 based on the coordinates of the wafer W corrected by the baseline
The XY stage 9 is driven so that X matches. As a result, alignment of each shot area of the wafer W with an accurate exposure position, that is, accurate alignment of the wafer W is performed (step S17). In step S18, it is determined whether or not the measurement has been completed for all the alignment marks on the wafer W. If the determination result is "NO", the process returns to step S11; if "YES", the process returns to step S11. The process ends.

In the above description, to simplify the description,
As shown in FIG. 4, the case where the one-dimensional alignment mark AM in the X-axis direction is formed has been described as an example. However, in order to measure the position in the Y-axis direction, as shown in FIG. It is necessary to form an alignment mark for detecting position information in the Y-axis direction.

As shown in FIG. 12, an alignment mark for detecting position information in the Y-axis direction is a rectangular mark element m ₃₁ , m whose longitudinal direction is set in the X-axis direction in the figure.
_{32, m 33,} m _34, the _{m 35} a first mark am11 arranged in the Y-axis direction, the mark elements _m 41 having the same shape as the mark elements _{m 31 ~m 35, m 42,} m 43, m 44,
m ₄₅ and m ₄₆ are set so that their longitudinal directions are in the X-axis direction,
Each of the second marks am12 is arranged in the Y-axis direction.

The first mark am11 and the second mark am12
Is the first mark am11 in the X-axis direction.
And each mark element _m 31 _{~m 35} and each mark element _m 41 _{~m 46} of the second mark am12 is arranged at a position shifted state so as not to overlap the. In this case, it is necessary to measure the position information of the alignment mark in the X-axis direction shown in FIG. 4 and to measure the position information of the alignment mark in the Y-axis direction shown in FIG.

Further, a two-dimensional alignment mark as shown in FIG. 13 may be used. As shown in FIG.
In the shape of the two-dimensional mark, each mark element is arranged in a check pattern (checkered pattern). In FIG. 13, each mark element is hatched. By using this two-dimensional mark, position information in the X-axis direction and the Y-axis direction can be obtained by one measurement.

The measurement of the position information using the two-dimensional mark is as follows.
First, image information of a two-dimensional mark is detected by the alignment sensor 14. Next, the alignment signal processing system 18 converts the obtained image information into lines D ₁ -D in FIG.
_{A first} light intensity signal is obtained at a position _{1 and} a second light intensity signal is obtained at a position of a line D ₂ -D _{2 in} the figure.
The third light intensity signal is calculated by performing the average addition processing.

The third light calculated by the average addition processing
X-axis position information of the two-dimensional mark based on the intensity signal
Is measured. Next, regarding the obtained image signal,
Line D ₃-D₃When the first light intensity signal is obtained at the position
Line D in the figure₄-D₄At the position of the second light intensity signal.
Signal, and performs an averaging process to obtain the third light intensity signal.
Calculate the number. The third calculated by this average addition process
The position information of the two-dimensional mark in the Y-axis direction based on the light intensity signal
Measure information. Thus, the X-axis direction and the Y-axis direction
Position information can be obtained.

The alignment marks shown in FIGS. 4, 5 and 12 are defined by the duty of the line and the space (line width / (line width + space width) or space width / (line width + space width). ) Is 50%, but this duty need not be limited to a constant, and can be set at random (irregular). By making them random, it is possible to reduce adverse effects due to aberrations and the like of the alignment sensor 14.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, in the above embodiment, the case where the position information of the alignment mark AM formed on the wafer W is detected has been described as an example. However, for example, the mark formed on the reticle R and the glass plate may be detected. The present invention can also be applied to the case of detecting position information of a formed mark.

In the above embodiment, the case where an off-axis type alignment sensor is used has been described as an example. However, an image of a mark captured by another type of alignment sensor is processed to determine a mark position. The present invention can be applied to detection.

The present invention is not limited to the step-and-repeat type exposure apparatus, but also includes a step-and-scan type exposure apparatus, a mirror projection type,
The present invention can be applied to an exposure apparatus such as a proximity method and a contact method.

Further, not only an exposure apparatus used for manufacturing a semiconductor element and a liquid crystal display element, but also an exposure apparatus, a reticle and a mask used for manufacturing a plasma display, a thin film magnetic head, and an image pickup element (CCD, etc.) are manufactured. For this purpose, the present invention can be applied to an exposure apparatus that transfers and forms a circuit pattern on a glass substrate, a silicon wafer, or the like.
That is, the present invention is applicable irrespective of the exposure method and application of the exposure apparatus.

As the light source of the exposure apparatus, g-line (436n
m), i-line (365 nm), KrF excimer laser (2
48 nm), ArF excimer laser (193 nm), F
₂ laser (157 nm), Kr ₂ laser (wavelength 146 nm), KrAr laser (wavelength 134 n
m) or an Ar ₂ laser (having a wavelength of 126 nm) or the like, and further, a charged particle beam such as an X-ray or an electron beam can be used.

Instead of using an F ₂ laser or an ArF excimer laser, a single-wavelength laser in the infrared or visible range oscillated from, for example, a DFB semiconductor laser or a fiber laser is used as erbium (or both erbium and yttrium). ) May be amplified by a doped fiber amplifier, and a harmonic converted into a UV light using a non-linear optical crystal may be used.

For example, the oscillation wavelength of a single-wavelength laser is set to 1.
When the wavelength is in the range of 51 to 1.59 μm, the generated wavelength is 18
An eighth harmonic having a wavelength in the range of 9 to 199 nm or a tenth harmonic having a generation wavelength in the range of 151 to 159 nm is output. Especially the oscillation wavelength is 1.544 to 1.553 μm
m, 8 in the range of 193 to 194 nm.
A harmonic wave, that is, ultraviolet light having substantially the same wavelength as the ArF excimer laser is obtained, and the oscillation wavelength is set to 1.57 to 1.58 μm.
m, 1 in the range of 157 to 158 nm.
0 harmonic, i.e., ultraviolet light having almost the same wavelength as the F ₂ laser is obtained.

The oscillation wavelength is set to 1.03 to 1.12 μm
, A 7th harmonic whose output wavelength is in the range of 147 to 160 nm is output.
Assuming that the wavelength is in the range of 099 to 1.106 μm, the generated harmonic is the seventh harmonic in the range of 157 to 158 μm, that is, F _2.
Ultraviolet light having substantially the same wavelength as the laser is obtained. In addition,
As a single-wavelength oscillation laser, ytterbium-doped
A fiber laser is used.

The projection optical system is not limited to a reduction system, but may be an equal magnification or enlargement system. The projection optical system, when using a far ultraviolet rays such as an excimer laser using a material which transmits far ultraviolet rays such as quartz and fluorite as glass material, a catadioptric or refractive system when using a F ₂ laser or X-ray An optical system (a reflection type mask is used for the mask). When an electron beam is used, an electron optical system including an electron lens and a deflector may be used as the optical system. It goes without saying that the optical path through which the electron beam passes is in a vacuum state.

By the way, the step of designing the function and performance of the circuit of the semiconductor element, the step of manufacturing a reticle, the step of manufacturing a silicon wafer based on this design step, and the steps of using the exposure apparatus described in the above embodiment are described. The reticle is manufactured through a step of transferring a reticle pattern onto a wafer, an assembling step (including a dicing step, a package step, and the like), an inspection step, and the like.

[0093]

As described above, according to the present invention, the first and second mark elements arranged so as to be mutually inverted while being displaced in the direction orthogonal to the arrangement direction on the substrate are electro-optically. A first light intensity signal and a second light intensity signal are obtained by scanning, a third light intensity signal is calculated by adding the first light intensity signal and the second light intensity signal, and a mark position is calculated. Therefore, even if the first light intensity signal and the second light intensity signal are single mark or double mark intensity signals, the obtained third light intensity signal is always a double mark intensity signal. Therefore, the mark can be detected by a single or a small number of detection algorithms, so that the time required for alignment can be shortened, and the compatibility of the detection algorithm with the mark intensity signal is improved, so that the alignment accuracy can be improved. Can be improved. As a result, the throughput of the exposure processing can be improved,
High-precision, high-quality micro devices and photomasks can be manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of an alignment sensor according to the embodiment of the present invention.

3A is a diagram illustrating an example of a field dividing diaphragm plate of the alignment sensor of FIG. 2, and FIG. 3B is a diagram illustrating an example of a light shielding plate.

FIG. 4 is a diagram illustrating a configuration of an alignment mark for detecting position information in the X-axis direction according to the embodiment of the present invention.

FIG. 5 is a sectional view taken along lines AA and BB in FIG. 4;

6 is a diagram for explaining the principle of always obtaining a double mark image signal using the alignment marks shown in FIGS. 4 and 5. FIG.

7 is a diagram for explaining the principle of always obtaining a double mark image signal using the alignment marks shown in FIGS. 4 and 5. FIG.

8 is a diagram for explaining the principle of always obtaining a double mark image signal using the alignment marks shown in FIGS. 4 and 5. FIG.

FIG. 9 is a flowchart showing an operation of position detection of the exposure apparatus according to the embodiment of the present invention.

FIG. 10 is a diagram illustrating a state in which an image of an alignment mark is formed on an imaging surface of an imaging element of the alignment sensor according to the embodiment of the present invention.

11 is a diagram showing a light intensity signal obtained when an image of an alignment mark is formed in the state shown in FIG.

FIG. 12 is a diagram illustrating an example of an alignment mark for detecting position information in the Y-axis direction according to the embodiment of the present invention.

FIG. 13 is a diagram illustrating an example of a two-dimensional mark as an alignment mark for detecting position information in the X and Y axis directions according to the embodiment of the present invention.

FIG. 14 is a diagram for explaining an edge detection method used for mark detection.

FIG. 15 is a diagram illustrating an example of a surface state of an alignment mark during measurement.

FIG. 16 is a diagram showing an image signal output from a CCD.

[Explanation of symbols]

2 ... Mask 3 ... Mask holder 5 ... Driver 8 ... Z stage 9 ... XY stage 12 ... Stage drive system 13 ... Main control system 14 ... Alignment sensor 18 ... Alignment signal processing system W ... Wafer (substrate, photosensitive substrate) AM ... Alignment mark (mark) am1 First mark (first direction mark) am2 Second mark (second direction mark) am11 First mark (first direction mark) am12 Second mark (second direction mark) m _{11 to} m ₁₅ first mark element m _{21 to} m ₂₆ second mark element m _{31 to} m ₃₅ first mark element m _{41 to} m ₄₆ second mark element

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 1/08 G03F 7/23 H 5F031 7/23 9/00 A 5F046 9/00 H01L 21 / 68F H01L 21/68 H05K 1/02 R H05K 1/02 H01L 21/30 525F F term (reference) 2F064 AA02 AA04 BB01 CC10 FF01 GG12 2F065 AA03 AA06 AA20 AA39 BB02 BB18 BB28 CC20 CC25 EE00 FF10 FF42 GG13H03 FF42 GG51H02 LL00 LL02 LL04 LL12 LL28 LL30 LL46 LL50 LL53 LL65 MM16 MM22 NN20 PP12 PP13 QQ03 QQ23 QQ24 QQ27 QQ29 QQ42 2H095 BA02 BE03 BE08 2H097 AB09 GB01 KA03 KA13 KA15 KA20 EA20 DD31 LA12 JA28 JA29 JA38 JA50 KA06 KA08 KA11 KA20 MA27 5F046 BA04 CC01 CC04 CC05 CC16 EA03 EA09 EB01 ED02 FA03 FA10 FA11 FA20 FB16 FC04 FC06

Claims (11)

[Claims] 1. An alignment method for aligning a posture of a substrate with a predetermined reference, comprising: a first and a second array arranged to be mutually inverted in a state of being displaced in a direction orthogonal to an arrangement direction on the substrate. A step of electro-optically scanning a mark including a mark element in the arrangement direction thereof to detect first and second light intensity signals whose intensity changes in the arrangement direction of the first and second mark elements; Identifying the position information of the mark based on a third light intensity signal obtained by adding the first light intensity signal and the second light intensity signal. 2. The alignment method according to claim 1, wherein the substrate is a photosensitive substrate or a mask. 3. The mark comprises: a first direction mark in which the first and second mark elements are arranged in a first direction;
3. The alignment method according to claim 1, further comprising: a second direction mark in which a second mark element is arranged in a second direction orthogonal to the first direction. 4. 4. The alignment method according to claim 1, wherein the mark has a check shape. 5. The alignment method according to claim 1, wherein an arrangement duty of the first and second mark elements is set at random. 6. An alignment device for aligning a posture of a substrate with a predetermined reference, comprising: a posture adjusting device for adjusting the posture of the substrate; A mark including first and second mark elements arranged to be inverted is electro-optically scanned in the arrangement direction, and first and second marks whose intensity changes in the arrangement direction of the first and second mark elements are changed. (2) a detection device for detecting a light intensity signal; and the posture so that the substrate matches a predetermined reference based on a third light intensity signal obtained by adding the first light intensity signal and the second light intensity signal. An alignment device, comprising: a control device for controlling the adjusting device. 7. A device substrate, wherein an alignment mark including first and second mark elements arranged so as to be inverted with respect to each other while being displaced in a direction orthogonal to the arrangement direction is formed. 8. A mask, wherein an alignment mark including first and second mark elements arranged so as to be mutually inverted while being displaced in a direction orthogonal to the arrangement direction is formed. 9. A mask, wherein a mark pattern including first and second mark element patterns arranged so as to be inverted with respect to each other while being displaced in a direction orthogonal to the arrangement direction is formed. 10. An exposure apparatus for projecting an image of a pattern of a mask onto a photosensitive substrate, a posture adjusting device for adjusting the posture of at least one of the photosensitive substrate and the mask, and a direction orthogonal to an arrangement direction on the photosensitive substrate. The first and second arrays are arranged to be inverted from each other in a state where they are misaligned.
A detecting device that electro-optically scans a mark including a mark element in an arrangement direction thereof and detects first and second light intensity signals whose intensity changes in the arrangement direction of the first and second mark elements; A control device that controls the attitude adjusting device based on a third light intensity signal obtained by adding the first light intensity signal and the second light intensity signal so that the attitudes of the photosensitive substrate and the mask match each other. An exposure apparatus, comprising: 11. A photoresist is applied on a substrate on which marks including the first and second mark elements are formed, and alignment between the mask and the substrate is performed using the alignment method according to claim 1. A device manufacturing method, comprising a step of transferring the pattern of the mask to the photoresist.