JP2004134473A - Mark for detecting position, position detector, position detecting method, aligner, and aligning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide marks for detecting position in which the position can be detected with high throughput and and highly accuracy by using one of the marks for superposition measurement also for detecting the position. <P>SOLUTION: The marks for detecting position are put on a substrate in order to detect the position of the substrate along one direction (X direction) and the position of the substrate along a second direction (Y direction) orthogonal to one direction (X direction). The marks have a first pattern (WMXa, WMXb) arranged along the first direction from the center (O) of the mark while spaced apart by a first distance (D1) and exhibiting periodicity in the first direction, and a second pattern (WMYa, WMYb) arranged along the second direction from the center while spaced apart by a second distance (D2) different from the first distance and exhibiting periodicity in the second direction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a position detection mark, a position detection device, a position detection method, an exposure device, and an exposure method. More specifically, the present invention relates to a position detection device mounted on an exposure apparatus used in a lithography process for manufacturing a micro device such as a semiconductor device, an imaging device, a liquid crystal display device, and a thin film magnetic head.
[0002]
[Prior art]
Generally, when manufacturing a device such as a semiconductor element, a plurality of circuit patterns are formed on a wafer (or a substrate such as a glass plate) on which a photosensitive material is applied. For this reason, an exposure apparatus for exposing a circuit pattern on a wafer includes an alignment apparatus for performing relative alignment (alignment) between a mask pattern and each exposure area of a wafer on which a circuit pattern has already been formed. Provided. In recent years, with the miniaturization of the line width of a circuit pattern, high-precision alignment has been required.
[0003]
2. Description of the Related Art Conventionally, as this type of alignment apparatus, an alignment apparatus of an off-axis type and an imaging type has been known as disclosed in JP-A-4-65603 and JP-A-4-273246. The detection system of this imaging type alignment apparatus is also called a FIA (Field Image Alignment) system position detection apparatus. In an FIA type position detecting device, an alignment mark (wafer mark) on a wafer is illuminated with light having a wide wavelength bandwidth emitted from a light source such as a halogen lamp. Then, an enlarged image of the wafer mark is formed on the imaging device via the imaging optical system, and the obtained imaging signal is subjected to image processing to detect the position of the wafer mark.
[0004]
Generally, when manufacturing a device such as a semiconductor element, a wafer mark is formed on a scribe line around a chip. Conventionally, as a wafer mark, an X-direction one-dimensional mark for detecting the position of the wafer along the X direction and a Y-direction one-dimensional mark for detecting the position of the wafer along the Y direction are formed independently. It had been. Here, the X-direction one-dimensional mark is an L / S (line and space) pattern having a periodicity along the X-direction, and the Y-direction one-dimensional mark is an L / S having a periodicity along the Y-direction. It is a pattern.
[0005]
However, in the related art in which a position detection mark is formed by two independent one-dimensional marks having periodicity in the X direction and the Y direction, a one-dimensional mark in the X direction and a one-dimensional mark in the Y direction are used. They cannot be captured simultaneously in the detection field of view. As a result, after the position of the wafer along the X direction is detected by photoelectrically detecting the light from the X-direction one-dimensional mark, the position of the wafer along the Y direction is detected by photoelectrically detecting the light from the Y-direction one-dimensional mark. Needs to be detected, and the throughput of position detection is low.
[0006]
For example, Japanese Patent Application Laid-Open No. Hei 10-189443 discloses a two-dimensional mark having periodicity in the X and Y directions as a position detection mark for improving the throughput of position detection (reducing the position detection time). Proposed. The two-dimensional mark disclosed in the publication includes a first pattern (M1) having periodicity in the Y direction, and a second pattern having periodicity in the X direction arranged near both sides of the first pattern in the X direction. It is composed of two patterns (M2a, M2b).
[0007]
[Patent Document 1]
JP-A-4-65603
[Patent Document 2]
JP-A-4-273246
[Patent Document 3]
JP-A-10-189443
[0008]
[Problems to be solved by the invention]
Incidentally, for example, in a photolithography process in a semiconductor manufacturing process, it is necessary to measure the amount of misalignment between a formed resist pattern and a base pattern. For this reason, using a so-called overlay measurement device, the overlay measurement mark formed by the first mark formed at the time of forming the base pattern and the second mark formed at the next formation of the resist pattern is photoelectrically detected. Then, the amount of misalignment of the two patterns is measured based on the amount of relative misalignment between the first mark and the second mark.
[0009]
Generally, the amount of misalignment generated between the resist pattern and the underlying pattern depends on the position detection error generated in the position detection device. In other words, high-accuracy position detection can be performed by correcting the detection result of the position detection device using the amount of misalignment between the resist pattern and the base pattern as the offset amount. However, in the prior art, since the position detection mark and the first mark that constitutes a part of the overlay measurement mark are formed independently, the first mark of the position detection mark and the overlay measurement mark is formed. However, there is a disadvantage that an error due to the difference is easily generated, and it is not possible to perform position detection with sufficiently high accuracy.
[0010]
The present invention has been made in view of the above-described problems, and can perform position detection with high throughput, and can perform high-accuracy position detection by using one of the overlay measurement marks. It is an object of the present invention to provide a position detection mark that can be performed. It is another object of the present invention to provide a position detecting device and a position detecting method capable of performing high-accuracy position detection with high throughput by using the position detection mark of the present invention.
[0011]
Further, using the highly accurate position detecting device and position detecting method of the present invention, for example, an exposure apparatus capable of performing good exposure by aligning a mask and a photosensitive substrate with high accuracy with respect to a projection optical system, for example. And an exposure method. Further, the present invention also provides an overlay measurement apparatus and an overlay measurement method capable of performing an overlay measurement with high accuracy by also using one of the overlay measurement marks with the position detection mark of the present invention. The purpose is to:
[0012]
[Means for Solving the Problems]
In order to solve the above-described problems, in a first embodiment of the present invention, a position of the substrate along a first direction and a position of the substrate along a second direction orthogonal to the first direction are formed on the substrate. In the position detection mark for detecting the position,
A first pattern arranged at a first distance from the center of the mark along the first direction and having a periodicity in the first direction; and a first pattern from the center along the second direction. A second pattern that is arranged at a second distance substantially different from the distance and that is periodic in the second direction.
[0013]
According to a preferred mode of the first mode, the pitch of the first pattern and the pitch of the second pattern are in the range of 2 μm to 16 μm. Further, it is preferable that a length dimension of the first pattern along the second direction and a length dimension of the second pattern along the first direction are in a range of 10 μm to 70 μm.
[0014]
According to a preferred mode of the first mode, a duty ratio W1 / P1 defined by a width dimension W1 of the line portion constituting the first pattern along the first direction and a pitch P1 of the first pattern. And a duty ratio W2 / P2 defined by a width dimension W2 of the line portion constituting the second pattern along the second direction and a pitch P2 of the second pattern is 50% or less. Further, it is preferable that a width dimension of the line part constituting the first pattern in the first direction and a width dimension of the line part constituting the second pattern in the second direction are 1 μm or more.
[0015]
Further, according to a preferred aspect of the first aspect, at least one of the line portion forming the first pattern and the line portion forming the second pattern has at least two segments having a line width of 1 μm or less. With lines. In this case, the duty ratio Ws / Ps defined by the line width Ws of the segment line and the pitch Ps of the segment line is preferably 30% or more.
[0016]
In a second embodiment of the present invention, an optical system for guiding light from the position detection mark of the first embodiment, a photoelectric detector for photoelectrically detecting light from the position detection mark, and an output signal of the photoelectric detector And a detection system for detecting the position of the position detection mark based on the position detection mark.
[0017]
In a third embodiment of the present invention, a step of guiding light from the position detection mark of the first embodiment through an optical system, and photoelectrically detecting the light from the position detection mark guided through the optical system. And a step of detecting a position of the position detection mark based on a result of the photoelectric detection.
[0018]
According to a fourth aspect of the present invention, there is provided an exposure apparatus for forming a predetermined circuit pattern on a photosensitive substrate, comprising: a position detecting device according to a second aspect for detecting a position of the photosensitive substrate. An exposure apparatus is provided.
[0019]
According to a fifth aspect of the present invention, in the exposure method for forming a predetermined circuit pattern on a photosensitive substrate, the position of the photosensitive substrate is detected by using the position detecting device of the second aspect or the position detecting method of the third aspect. An exposure method is provided.
[0020]
In a sixth aspect of the present invention, an optical system for guiding light from an overlay measurement mark including the position detection mark of the first aspect and a second mark formed in a central space of the position detection mark, A photoelectric detector for photoelectrically detecting light from the overlay measurement mark, and measuring an overlay displacement amount between the position detection mark and the second mark based on an output signal of the photoelectric detector. An overlay measurement device is provided.
[0021]
In a seventh aspect of the present invention, a step of forming a second mark in the center space of the position detection mark of the first aspect, and light from an overlay measurement mark comprising the position detection mark and the second mark Guiding the light via the optical system, the step of photoelectrically detecting light from the overlay measurement mark guided through the optical system, and the position detection mark and the light based on the result of the photoelectric detection Measuring the amount of misalignment with the second mark.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram schematically illustrating a configuration of an exposure apparatus including a position detection device according to an embodiment of the present invention. FIG. 2 is a diagram schematically illustrating a configuration of a position detection mark (wafer mark) formed on a wafer that is an object to be position-detected by the position detection device of the present embodiment.
[0023]
In the present embodiment, the present invention is applied to an FIA-based position detecting device for detecting the position of a photosensitive substrate in an exposure device for manufacturing a semiconductor element. In FIG. 1, the Z axis is parallel to the optical axis AX0 of the projection optical system PL of the exposure apparatus, the X axis is a direction parallel to the plane of FIG. 1 in a plane perpendicular to the Z axis, and the Z axis is The Y-axis is set in a direction perpendicular to the plane of FIG. 1 in a vertical plane.
[0024]
Referring to FIG. 1, the exposure apparatus of the present embodiment includes an exposure illumination system IL for illuminating a reticle R as a mask (projection master) with appropriate exposure light. The reticle R is supported substantially parallel to the XY plane on the reticle stage 30, and a circuit pattern to be transferred is formed in the pattern area PA. The light transmitted through the reticle R reaches the wafer W as a photosensitive substrate via the projection optical system PL, and a pattern image of the reticle R is formed on the wafer W.
[0025]
The wafer W is supported on the Z stage 32 via the wafer holder 31 substantially in parallel with the XY plane. The Z stage 32 is configured to be driven by the stage control system 34 in the Z direction along the optical axis AX0 of the projection optical system PL. The Z stage 32 is further supported on an XY stage 33. The XY stage 33 is also configured to be driven two-dimensionally by the stage control system 34 in an XY plane perpendicular to the optical axis AX0 of the projection optical system PL.
[0026]
As described above, in the exposure apparatus, it is necessary to optically align (align) the pattern area PA on the reticle R and each exposure area on the wafer W prior to the projection exposure. Therefore, a wafer mark (a mark for position detection) WM as schematically shown in FIG. 2 is formed on the wafer W which is an object to be position-detected. The position detecting device of the present embodiment is used to detect the position of the wafer mark WM, and thus the position of the wafer W.
[0027]
Referring to FIG. 2, the position detection mark, ie, the wafer mark WM of the present embodiment is arranged at a distance D1 (first distance) from the center O along the X direction (first direction) and is spaced apart from the center O by X1. X-direction patterns (first patterns) WMXa and WMXb having periodicity in the direction and spaced from the center O by a distance D2 (second distance) substantially different from the distance D1 along the Y direction (second direction) in the Y direction (second direction). And YMY patterns (second patterns) WMYa and WMYb having periodicity in the Y direction.
[0028]
Specifically, the X-direction patterns WMXa and WMXb are formed by arranging three rectangular line portions elongated in the Y direction at a predetermined pitch P1 in the X direction. It is a pattern. The Y-direction patterns WMYa and WMYb are L / S patterns formed by arranging three rectangular line portions elongated in the X direction at a predetermined pitch P2 in the Y direction. . A more detailed configuration and operation of the wafer mark WM will be described later.
[0029]
Referring to FIG. 1 again, the position detection device according to the present embodiment includes a light source 1 for supplying illumination light having a wide wavelength bandwidth (for example, 530 nm to 800 nm). As the light source 1, a light source such as a halogen lamp can be used. Illumination light supplied from the light source 1 is incident on an incident end of a light guide 2 such as an optical fiber via a relay optical system (not shown). Illumination light propagating inside the light guide 2 and emitted from the exit end thereof is restricted via the illumination aperture stop 3 having, for example, a circular opening (light transmitting portion), and is then transmitted to the condenser lens 4. Incident.
[0030]
The illumination light passing through the condenser lens 4 is incident on the illumination relay lens 6 via the illumination field stop 5 that is arranged almost optically conjugate with the exposure surface of the wafer W that is the object to be illuminated. The illumination light via the illumination relay lens 6 passes through the half prism 7 and then enters the first objective lens 8. The illumination light having passed through the first objective lens 8 is reflected downward (in the −Z direction) in the drawing on the reflection surface of the reflection prism 9 and then illuminates the wafer mark WM formed on the wafer W.
[0031]
Thus, the light source 1, the light guide 2, the illumination aperture stop 3, the condenser lens 4, the illumination field stop 5, the illumination relay lens 6, the half prism 7, the first objective lens 8, and the reflection prism 9 illuminate the wafer mark WM. And an illumination optical system for performing the operation. The reflected light (including the diffracted light) from the wafer mark WM with respect to the illumination light enters the half prism 7 via the reflecting prism 9 and the first objective lens 8. The light reflected upward (in the + Z direction) in the figure by the half prism 7 forms an image of the wafer mark WM on the index plate 11 via the second objective lens 10.
[0032]
The light passing through the index plate 11 is incident on a CCD 14 as an image sensor via a relay lens system (12, 13). An image forming aperture stop 15 is arranged in the parallel optical path of the relay lens system (12, 13). As described above, the reflecting prism 9, the first objective lens 8, the half prism 7, the second objective lens 10, the index plate 11, the relay lens system (12, 13), and the image forming aperture stop 15 serve as a wafer mark for the illumination light. An image forming optical system for forming a mark image based on the reflected light from the WM is configured.
[0033]
Further, the CCD 14 constitutes a photoelectric detector for photoelectrically detecting a mark image formed via an imaging optical system. Thus, a mark image is formed on the imaging surface of the CCD 14 together with the index pattern image of the index plate 11. An output signal from the CCD 14 is supplied to a signal processing system 16. Further, the position information of the wafer mark WM obtained by the signal processing (waveform processing) in the signal processing system 16 is supplied to the main control system 35. The main control system 35 outputs a stage control signal to the stage control system 34 based on the position information of the wafer mark WM from the signal processing system 16.
[0034]
The stage control system 34 appropriately drives the XY stage 33 in accordance with the stage control signal to perform alignment of the wafer W. Note that a command for the illumination aperture stop 3 and a command for the imaging aperture stop 15 are supplied to the main control system 35 via input means 36 such as a keyboard. The main control system 35 drives the illumination aperture stop 3 via the drive system 17 and drives the imaging aperture stop 15 via the drive system 18 based on these commands.
[0035]
In the present embodiment, the wafer W on which the resist is applied is set in an exposure apparatus, and a predetermined circuit pattern is formed on the resist of the wafer W. Next, the wafer W on which the resist pattern is formed is removed from the exposure apparatus, and a process such as resist removal and etching is performed. As a result, an n-th layer circuit pattern is formed on the wafer W, and a wafer mark WM as a position detection mark is formed on the scribe line.
[0036]
Thereafter, the wafer W on which the resist has been re-applied is set in the exposure apparatus, and the position information of the wafer mark WM and thus the position information of the wafer W are detected by the position detecting apparatus. After optically aligning each exposure area of the wafer W with the pattern area PA on the reticle R based on the position information of the wafer W, a predetermined circuit pattern is formed on the resist of the wafer W. At this time, when forming the resist pattern, an inner mark IM described later is formed in the central space of the wafer mark WM.
[0037]
FIG. 3 is a diagram illustrating a state in which a wafer mark serving as a position detection mark according to the present embodiment also serves as an outer mark of the overlay measurement mark. In the present embodiment, a rectangular space having a size of 2 × D1 in the X direction and a size of 2 × D2 in the Y direction is formed at the center of the wafer mark WM with the center O as the center. . Therefore, as shown in FIG. 3, it is possible to form a superimposed measurement mark using the wafer mark WM as the outer mark and the inner mark IM formed in the center space by using the central space of the wafer mark WM. it can. Although FIG. 3 illustrates the inner mark IM having a rectangular shape, the present invention is not limited to this. The inner mark IM is formed by four independent line portions corresponding to four sides of the rectangle. It can also be configured. Further, the inner mark IM may have a square shape instead of a rectangular shape.
[0038]
Thus, in the present embodiment, the wafer W on which the resist pattern for the (n + 1) th layer is formed is removed from the exposure apparatus, and prior to a predetermined process, the overlay measurement apparatus 37 (see FIG. )). The overlay measurement device 37 detects, for example, an illumination system (not shown) that illuminates the overlay measurement mark, an imaging optical system (not shown) that forms an image of the overlay measurement mark, and an image of the overlay measurement mark. And a detection system (not shown) for measuring the overlay displacement between the outer mark (first mark) and the inner mark (second mark). When performing the overlay measurement, all of the wafer marks WM shown in FIG. 3 may be used as the outer marks, or only the pattern closest to the inner mark IM among the wafer marks WM may be used.
[0039]
If the measured overlay deviation is within the allowable range, the wafer W undergoes a predetermined process to form a (n + 1) th layer circuit pattern. On the other hand, if the measured overlay deviation exceeds the allowable range, the exposed resist on the wafer W is removed, a new resist is applied, and the wafer W is set in an exposure apparatus. Based on the position information obtained by correcting the detection result of the detection device, each exposure region of the wafer W and the pattern region PA on the reticle R are optically re-positioned. Then, a predetermined circuit pattern is formed on the resist on the aligned wafer W.
[0040]
As described above, in the present embodiment, since the wafer mark WM as the position detection mark has a form of a two-dimensional mark having periodicity in the X direction and the Y direction, the X direction patterns WMXa and WMXb and the Y direction pattern WMYa And WMYb can be simultaneously captured in the detection field of view of the position detection device, and position detection can be performed with high throughput. Further, in the present embodiment, since the wafer mark WM serving as the position detection mark also serves as the outer mark of the overlay measurement mark, the overlay displacement amount measured with high accuracy is used as the offset amount to determine the position of the position detection device. The detection result can be corrected with high accuracy, and thus highly accurate position detection can be performed.
[0041]
Furthermore, in the present embodiment, since the space formed at the center of the wafer mark WM as the position detection mark has a rectangular shape instead of a square shape, the entire shape of the wafer mark WM also extends in one direction. It becomes rectangular. Therefore, the position detection mark of the present embodiment has an advantage that the degree of freedom in arranging the wafer mark WM on the elongated scribe line is high after securing a pattern having a required number of lines.
[0042]
In the present embodiment, the centers of the X-direction patterns WMXa and WMXb coincide with the centers of the Y-direction patterns WMYa and WMYb. Therefore, in the position detection mark of the present embodiment, as specified in the above-mentioned Japanese Patent Application Laid-Open No. 10-189443, the influence of the aberration remaining on the optical system of the position detection device on the position detection accuracy should be minimized. Thus, highly accurate position detection can be performed.
[0043]
In the present embodiment, it is preferable that the pitch P1 between the X-direction patterns WMXa and WMXb and the pitch P2 between the Y-direction patterns WMYa and WMYb be in the range of 2 μm to 16 μm. That is, if the pitches P1 and P2 are set to be smaller than 2 μm, the position detection accuracy is likely to decrease, which is inconvenient. On the other hand, if the pitches P1 and P2 are set to be larger than 16 μm, it is inconvenient because the overall size of the mark becomes large.
[0044]
In the present embodiment, the length dimension L1 of the X direction patterns WMXa and WMXb along the Y direction (the non-measurement direction of the X direction pattern) and the X direction of the Y direction patterns WMYa and WMYb (the non-measurement direction of the Y direction pattern) ) Is preferably in the range of 10 μm to 70 μm. That is, if the lengths L1 and L2 are set to be smaller than 10 μm, the averaging effect in the non-measurement direction is reduced, and the position detection accuracy is easily reduced, which is inconvenient. On the other hand, if the lengths L1 and L2 are set to be larger than 70 μm, the overall size of the mark becomes large, which is inconvenient.
[0045]
FIG. 4 is a diagram for explaining dishing and erosion that occur during the planarization processing by the CMP method. In recent years, the number of processes using a copper (copper) wiring instead of an aluminum wiring has increased, and a case where a flattening processing by a CMP method has been used has increased. In general, when the surfaces of the insulating layer 40 and the line portion 41 are flattened by using the CMP method, as shown in FIG. 4A, the surface of the line portion 41 made of, for example, copper (Cu) is dish-shaped with an asymmetrical depression. In the form of This phenomenon is called "dishing". The dishing does not depend on the pattern density (line width / pitch) but depends on the line width of the line portion. For example, the dishing easily occurs in the line portion having a line width of 1 μm or more.
[0046]
In this case, an opaque layer 42 such as an aluminum layer is formed on the flattened surface, and the surface portion of the opaque layer 42 corresponding to the surface portion of the line portion 41 is also asymmetrically depressed. Therefore, when dishing occurs during the planarization processing by the CMP method, it is not necessary to partially remove only the mark area of the opaque layer 42 at the time of position detection, and position detection is performed using the asymmetrically recessed step of the opaque layer 42. be able to. In other words, if dishing does not occur during the planarization processing by the CMP method, position detection cannot be performed unless the opaque layer 42 is partially removed.
[0047]
On the other hand, as shown in FIG. 4B, when the surfaces of the plurality of line portions 43 constituting the L / S pattern having a relatively large duty ratio (the pattern density is relatively large) are flattened by the CMP method, The surface of the insulating layer 40 and the line portion 43 is depressed over substantially the entire L / S pattern including the line portion 43. This phenomenon is called "erosion". Erosion depends on the pattern density without depending on the line width of the line portion. For example, erosion is likely to occur in a region having a pattern density of 30% to 50% or more. If the erosion occurs in a region other than the alignment mark WM during the planarization process by the CMP method, it is not desirable because it affects the IC chip. As described above, as an advantageous mark even when the planarization processing by the CMP method is performed, a mark in which dishing easily occurs and erosion hardly occurs around the alignment mark.
[0048]
In the present embodiment, the pattern density (W1 / P1) of the X-direction patterns WMXa and WMXb and the pattern density (W2 / P2) of the Y-direction patterns WMYa and WMYb are preferably 50% or less. Here, W1 is the width dimension along the X direction of the line portions constituting the X-direction patterns WMXa and WMXb, and W2 is the width dimension along the Y direction of the line portions constituting the Y-direction patterns WMYa and WMYb. .
[0049]
If the duty ratios W1 / P1 and W2 / P2 are set to be greater than 50%, the so-called pattern density becomes too large, and erosion is likely to occur during flattening processing by a CMP (Chemical Mechanical Polishing) method, which is inconvenient. In order to more reliably avoid the occurrence of erosion, it is more preferable to set the pattern densities W1 / P1 and W2 / P2 to 40% or less.
[0050]
Further, in the present embodiment, it is preferable that the width dimension W1 of the line section forming the X-direction patterns WMXa and WMXb and the width dimension W2 of the line section forming the Y-direction patterns WMYa and WMYb be 1 μm or more. If the width dimensions W1 and W2 of the line portion are set smaller than 1 μm, dishing hardly occurs during the planarization process by the CMP method, and there is a high possibility that position detection cannot be performed unless the opaque layer is partially removed. Become.
[0051]
FIG. 5 is a diagram schematically illustrating a configuration of a position detection mark (wafer mark) according to a modification of the present embodiment. Referring to FIG. 5, the wafer mark according to the modification has a configuration generally similar to the wafer mark of the embodiment shown in FIG. However, in the wafer mark according to the modified example, each line portion has a line width Ws in the pitch direction and is formed by three segment lines SL arranged at a pitch Ps in the embodiment shown in FIG. This is basically different from the wafer mark.
[0052]
Thus, by forming one line portion by the L / S pattern including three segment lines SL, even if the line width Ws of each segment line SL is small, the line portion including three segment lines SL Since the width dimension (2 × Ps + Ws) becomes relatively large, erosion occurs in the area of the line portion, and even if an opaque film is provided thereon, the opaque film is as accurate as the wafer mark of the embodiment shown in FIG. Position detection is possible. Further, since the pattern density in the X direction patterns WMXa and WMXb and the pattern density in the Y direction patterns WMYa and WMYb are reduced, there is an advantage that erosion hardly occurs around each of the patterns WMXa, WMXb, WMYa, and WMYb.
[0053]
In the modification, the line width Ws of each segment line SL is preferably 1 μm or less. With this configuration, occurrence of dishing in each segment line SL can be suppressed. In the modification, the duty ratio Ws / Ps defined by the line width Ws of the segment line SL and the pitch Ps of the segment line is preferably 30% or more. With this configuration, erosion is likely to occur over one entire line portion including three segment lines SL.
[0054]
In this case, the erosion that occurs over the entire one line portion performs the same operation as dishing that occurs in the line portion as shown in FIG. As a result, erosion over the whole of each of the patterns WMXa, WMXb, WMYa, and WMYb is unlikely to occur, and a phenomenon equivalent to dishing is likely to occur in each line portion. Can be realized. By setting the duty ratio Ws / Ps to 40% or more, erosion can be more easily caused over the entire line portion.
[0055]
In the above-described modification, one line portion is configured by the L / S pattern including three segment lines SL. However, the present invention is not limited to this, and one line portion is configured by at least two segment lines. It can also be configured. Instead of a plurality of independent segment lines, for example, one line portion can be constituted by a pattern corresponding to two sides facing each other of an elongated rectangle.
[0056]
In the above-described embodiment, the wafer mark is illuminated by epi-illumination. However, the present invention is not limited to this, and the present invention can be applied to a position detection device that illuminates the wafer mark by transmission. Further, in the above-described embodiment, the present invention is applied to the position detection device including the imaging optical system that forms an image based on light from a wafer mark, but is not limited thereto. In general, the present invention can be applied to a position detecting device having an optical system for guiding light from a wafer mark.
[0057]
Further, in the above-described embodiment, the present invention is applied to the projection exposure apparatus. However, the present invention is not limited to this, and a proximity type exposure apparatus, an X-ray exposure apparatus that performs pattern transfer using X-rays, The present invention can also be applied to an EB (electron beam) exposure apparatus (including direct drawing) that performs pattern transfer using an electron beam.
[0058]
In the above-described embodiment, the position of the photosensitive substrate in the exposure apparatus is detected. However, the present invention is not limited to this, and the position of an object mark formed on a general object to be detected can be detected. Thus, the present invention can also be applied.
[0059]
【The invention's effect】
As described above, in the present invention, since the position detection mark has the form of a two-dimensional mark having periodicity in the X direction and the Y direction, the X direction pattern and the Y direction pattern are within the detection field of the position detection device. And the position can be detected with high throughput. Further, in the present invention, since the position detection mark also serves as one of the overlay measurement marks, the detection result of the position detection device is used as an offset amount with the overlay displacement amount measured with high accuracy. Correction can be performed with high accuracy, and thus highly accurate position detection can be performed.
[0060]
Therefore, with the position detecting device and the position detecting method of the present invention, high-accuracy position detection can be performed with high throughput by using the position detecting mark of the present invention. Further, in the exposure apparatus and the exposure method of the present invention, for example, the mask and the photosensitive substrate are highly accurately aligned with respect to the projection optical system by using the high-precision position detection apparatus and the position detection method of the present invention. Good exposure can be performed. Further, in the overlay measuring apparatus and the overlay measuring method of the present invention, high-accuracy overlay measurement can be performed by also using one of the overlay measuring marks with the position detecting mark of the present invention. Can be.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating a configuration of an exposure apparatus including a position detection device according to an embodiment of the present invention.
FIG. 2 is a diagram schematically showing a configuration of a position detection mark (wafer mark) formed on a wafer which is an object to be position-detected by the position detection device of the present embodiment.
FIG. 3 is a diagram illustrating a state in which a wafer mark as a position detection mark according to the present embodiment also serves as an outer mark of the overlay measurement mark.
FIG. 4 is a diagram illustrating dishing and erosion that occur during planarization processing by a CMP method.
FIG. 5 is a diagram schematically showing a configuration of a position detection mark according to a modification of the embodiment.
[Explanation of symbols]
1 Halogen lamp
2 Light guide
3 Illumination aperture stop
5. Illumination field stop
7 Half prism
8 First objective lens
9 Reflective prism
10 Second objective lens
11 Indicator board
14 CCD
15 Image aperture stop
16 Signal processing system
30 reticle stage
31 Wafer holder
32 Z stage
33 XY stage
34 Stage control system
35 Main control system
36 keyboard
37 Overlay measuring device
Illumination system for IL exposure
R reticle
PA pattern area
PL projection optical system
W wafer
WM wafer mark

Claims (13)

A position detection mark formed on a substrate for detecting a position of the substrate along a first direction and a position of the substrate along a second direction orthogonal to the first direction;
A first pattern arranged at a first distance from the center of the mark in the first direction and having a periodicity in the first direction; and a first pattern extending from the center in the second direction. A second pattern that is arranged at a second distance substantially different from the distance and that is periodic in the second direction. The position detection mark according to claim 1, wherein the pitch of the first pattern and the pitch of the second pattern are within a range of 2 m to 16 m. The length dimension of the first pattern along the second direction and the length dimension of the second pattern along the first direction are in a range of 10 μm to 70 μm. Mark for position detection. The duty ratio W1 / P1 defined by the width dimension W1 along the first direction of the line portion constituting the first pattern and the pitch P1 of the first pattern, and the duty ratio W1 / P1 of the line portion constituting the second pattern 4. The duty ratio W2 / P2 defined by a width dimension W2 along the second direction and a pitch P2 of the second pattern is 50% or less, according to claim 1, wherein: Mark for position detection described. The width of the line portion forming the first pattern along the first direction and the width of the line portion forming the second pattern along the second direction are 1 μm or more. Item 5. The position detection mark according to any one of Items 1 to 4. 4. The device according to claim 1, wherein at least one of the line part forming the first pattern and the line part forming the second pattern has at least two segment lines having a line width of 1 μm or less. 3. The position detection mark according to any one of 3. The position detection mark according to claim 6, wherein a duty ratio Ws / Ps defined by a line width Ws of the segment line and a pitch Ps of the segment line is 30% or more. An optical system for guiding light from the position detection mark according to any one of claims 1 to 7, a photoelectric detector for photoelectrically detecting light from the position detection mark, and an output signal of the photoelectric detector. And a detection system for detecting the position of the position detection mark based on the position detection mark. A step of guiding light from the position detection mark according to claim 1 through an optical system, and photoelectrically detecting light from the position detection mark guided through the optical system. And detecting the position of the position detection mark based on the result of the photoelectric detection. In an exposure apparatus for forming a predetermined circuit pattern on a photosensitive substrate,
An exposure apparatus comprising: the position detection device according to claim 8 for detecting a position of the photosensitive substrate. In an exposure method for forming a predetermined circuit pattern on a photosensitive substrate,
An exposure method comprising detecting the position of the photosensitive substrate using the position detection device according to claim 8 or the position detection method according to claim 9. An optical system for guiding light from an overlay measurement mark comprising the position detection mark according to any one of claims 1 to 7 and a second mark formed in a central space of the position detection mark, A photoelectric detector for photoelectrically detecting light from the overlay measurement mark, and measuring an overlay displacement amount between the position detection mark and the second mark based on an output signal of the photoelectric detector. An overlay measurement device characterized by the following. A step of forming a second mark in a center space of the position detection mark according to any one of claims 1 to 7, and a step of detecting a position of the position detection mark from an overlay measurement mark including the position detection mark and the second mark. A step of guiding light through an optical system, a step of photoelectrically detecting light from the overlay measurement mark guided through the optical system, and the position detection mark based on the result of the photoelectric detection. Measuring the amount of misalignment with the second mark.

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