JP2004354230A - Position detecting apparatus, exposure apparatus and exposure method - Google Patents

Abstract

For example, a position detecting device capable of stably and highly accurately detecting the surface position of a mask protected by a pellicle film while suppressing the influence of the reflectance spectral characteristics of the pellicle film.
A position detecting device detects a surface position of a substrate (M) covered with a thin film (PR) at intervals. An irradiation system (1 to 11) for irradiating the surface of the substrate with the detection light beam obliquely, and photoelectrically detecting the detection light beam reflected on the surface of the substrate, and detecting the surface position of the substrate based on the photoelectric output. (12 to 15). The irradiation system irradiates the surface of the substrate with a detection light beam having spectral characteristics according to the reflectance spectral characteristics of the thin film in order to suppress the influence caused by the thin film.
[Selection] Figure 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a position detection device, an exposure device, and an exposure method. More specifically, the present invention relates to a position detection device that detects a surface position of a mask (or reticle) with a pellicle film in an exposure apparatus used in a lithography process for manufacturing a semiconductor element, a liquid crystal display element, and the like.
[0002]
[Prior art]
When manufacturing devices such as semiconductor elements and liquid crystal display elements, a mask (reticle, photomask, etc.) pattern is formed on a photosensitive substrate (glass plate, semiconductor wafer, etc.) coated with a photoresist via a projection optical system. Is used. Heretofore, a projection exposure apparatus (stepper) for sequentially exposing a mask pattern to each shot area on a photosensitive substrate by a so-called step-and-repeat method has been frequently used.
[0003]
On the other hand, for example, in Japanese Patent Laid-Open No. 7-57986, a mask pattern is formed by using a plurality of small partial projection optical systems arranged in a staggered pattern instead of using one large projection optical system. An exposure apparatus that sequentially scans and exposes each shot area on a substrate has been proposed. In this type of exposure apparatus, light from a light source such as an ultra-high pressure mercury lamp is split into an illumination optical path for each partial projection optical system via a light guide, and illuminates a plurality of trapezoidal regions on a mask. .
[0004]
Light transmitted through each trapezoidal region on the mask forms a mask pattern image on the photosensitive substrate via each partial projection optical system that forms, for example, an equal-size erect image. Thus, scanning exposure is performed while the mask and the photosensitive substrate are relatively moved in the same direction with respect to each partial projection optical system. As a result, a relatively large mask pattern can be exposed to one shot area on the photosensitive substrate while overlapping part of the pattern image formed via the partial projection optical system adjacent to each other.
[0005]
The photosensitive substrate used in this type of exposure apparatus tends to be very large due to an increase in the size of a liquid crystal display element, a demand for a high yield, an increase in the number of chamfers, and the like. For example, it is necessary to use a large photosensitive substrate having a size of 1 m square or more, and accordingly, a mask as an original to be projected onto the photosensitive substrate is also following a path of increasing size. Even if the mask becomes large, it is necessary to support (hold) the mask only by the surrounding area, as in the case of the conventional small mask, in order to secure a use area at the time of exposure. As a result, in the case of a large mask, the deflection of the central portion becomes large, and the focal position shift of the mask pattern with respect to the depth of focus of the projection optical system cannot be ignored.
[0006]
In a conventional exposure apparatus, the position of a projection optical system with respect to a holder for holding a mask is adjusted in advance, and a photosensitive substrate provided at a position where a mask pattern image is formed via the projection optical system is used. The position in the vertical direction (the optical axis direction of the projection optical system) is detected, and the focus of the photosensitive substrate with respect to the projection optical system is adjusted. However, since the influence of the deflection of the mask cannot be ignored, the surface position of the mask in the vertical direction is also detected, and the focus of the mask with respect to the projection optical system is also adjusted.
[0007]
For example, Japanese Patent Application Laid-Open No. H11-258498 discloses an apparatus for detecting a vertical surface position of a mask or a photosensitive substrate. The position detection device disclosed in this publication irradiates a mask or a photosensitive substrate with a slit-like light beam from an oblique direction, detects reflected light from the surface of the mask or the photosensitive substrate, and detects the reflected light based on the detection position of the reflected light. To detect the position of the surface of the mask or photosensitive substrate. In this type of oblique incidence type position detection device, an LED is used as a light source from the viewpoint of long life, low cost, and space saving.
[0008]
By the way, if dust or foreign matter adheres to the pattern surface of the mask, these may be transferred to the photosensitive substrate and cause a circuit disconnection or the like. For this reason, a thin film called a pellicle is stretched at a certain distance from the pattern surface to protect the pattern surface from adhesion of dust and foreign matter. In this case, even if dust or foreign matter adheres to the pellicle film, an image of the dust or foreign matter is substantially formed on the photosensitive substrate because a required distance is secured between the pellicle film and the pattern surface. Without that, the effect can be reduced. The pellicle film is made of a material with low light absorption in the exposure wavelength range to minimize the loss of exposure light, and has a single-layer structure with a controlled refractive index and thickness to reduce the exposure light reflectance. Alternatively, it has a multi-layer (three-layer, five-layer, etc.) structure.
[0009]
[Patent Document 1]
JP-A-11-258498
[0010]
[Problems to be solved by the invention]
An LED which is currently widely used as a light source in a conventional oblique incidence type position detecting device has a half width of about 30 nm, a center wavelength of about 780 nm, and a wavelength shift width of about 60 nm (± 30 nm). ). On the other hand, the pellicle film currently used has a large wavelength dependence of the reflectance with respect to obliquely incident light, and a relatively large variation (variation) in the film thickness.
[0011]
For this reason, in the related art using an LED whose wavelength range is narrow and the wavelength band is apt to fluctuate due to wavelength shift, it is obtained when the reflected light from the mask surface is photoelectrically detected due to the reflectance spectral characteristics of the pellicle film. The level fluctuation of the photoelectric output tends to increase. Even if the wavelength shift does not occur, the reflectance spectral characteristic changes in the wavelength direction due to the variation in the thickness of the pellicle film. Therefore, the photoelectric output level is changed due to the change in the reflectance spectral characteristic in the wavelength direction. Is likely to fluctuate. As a result, in the related art, securing the dynamic range of the light receiving sensor and adjusting the output level of the light receiving sensor have become a heavy burden.
[0012]
The present invention has been made in view of the above-described problems, and for example, detects the surface position of a mask protected by a pellicle film stably and with high accuracy while suppressing the influence of the reflectance spectral characteristics of the pellicle film. It is an object of the present invention to provide a position detecting device capable of detecting a position. Further, the present invention uses a position detection device capable of detecting the surface position of a mask protected by a pellicle film stably and with high accuracy, and sets the mask with high accuracy to the projection optical system. It is an object of the present invention to provide an exposure apparatus and an exposure method capable of performing a good exposure by using the same.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, in a first embodiment of the present invention, in a position detection device that detects a surface position of a substrate covered with a thin film at an interval,
An irradiation system for irradiating the detection light beam obliquely to the surface of the substrate,
The detection light beam reflected on the surface of the substrate photoelectrically detected, comprising a detection system for detecting the surface position of the substrate based on the photoelectric output,
A position detection device, wherein the irradiation system irradiates a surface of the substrate with a detection light beam having a spectral characteristic according to a reflectance spectral characteristic of the thin film in order to suppress an influence caused by the thin film. I do.
[0014]
According to a preferred mode of the first embodiment, the detection light beam has a required spectral characteristic for suppressing a level change of the photoelectric output caused by the thin film. Further, it is preferable that the irradiation system irradiates the surface of the substrate with a detection light beam having a wavelength range larger than one cycle of the reflectance spectral characteristic of the thin film. Alternatively, the irradiation system irradiates the surface of the substrate with a detection light beam including a plurality of wavelength lights in which an interval between a minimum center wavelength and a maximum center wavelength is set to be longer than one cycle of the reflectance spectral characteristic of the thin film. Is preferred.
[0015]
According to a second aspect of the present invention, there is provided an exposure apparatus for illuminating a mask protected by a pellicle film and exposing a pattern formed on the mask onto a photosensitive substrate, wherein a first position for detecting a surface position of the mask is provided. An exposure apparatus comprising the position detecting device according to the first aspect.
[0016]
According to a third aspect of the present invention, there is provided an exposure method for illuminating a mask protected by a pellicle film and exposing a pattern formed on the mask onto a photosensitive substrate. A step of detecting a surface position of the light source.
[0017]
According to a fourth aspect of the present invention, there is provided an exposure method for illuminating a mask protected by a pellicle film and exposing a pattern formed on the mask onto a photosensitive substrate.
On the surface of the mask protected by the pellicle film, obliquely irradiate a light beam having spectral characteristics to suppress the influence of the reflectance spectral characteristics of the pellicle film,
An exposure method is provided wherein the position of the surface of the mask is measured by detecting light reflected from the surface due to the irradiation.
[0018]
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. In the present embodiment, the present invention is applied to a position detecting device for detecting a surface position of a mask protected by a pellicle film. In FIG. 1, the Z axis is parallel to the optical axis of the projection optical system PL, 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 a plane perpendicular to the Z axis. The Y-axis is set in a direction perpendicular to the plane of FIG.
[0019]
Referring to FIG. 1, the exposure apparatus of the present embodiment includes an exposure illumination system IL for illuminating a mask (projection master) M in a superimposed manner with light from a suitable light source such as a mercury lamp. . The mask M is supported on the mask stage MS substantially in parallel with the XY plane, and a circuit pattern to be transferred is formed in the pattern area PA. The mask stage MS is configured to be driven along the optical axis of the projection optical system PL by a control system (not shown).
[0020]
The light illuminated by the exposure illumination system IL and transmitted through the mask M reaches a plate P as a photosensitive substrate via the projection optical system PL, and a pattern image of the mask M is formed on the plate P. The plate P is supported on the plate stage PS substantially parallel to the XY plane. The plate stage PS is also driven by the control system in the optical axis direction of the projection optical system PL and is two-dimensionally driven in an XY plane perpendicular to the optical axis of the projection optical system PL. I have.
[0021]
In this manner, by performing the scanning exposure while moving the mask M and the plate P relative to the projection optical system PL, the mask pattern is transferred to one shot area on the plate P. In the exposure apparatus, it is necessary to set the pattern surface of the mask M and the exposure surface of the plate P for the projection optical system PL prior to the projection exposure. Therefore, the illustrated exposure apparatus includes a position detection device for the mask M for detecting the surface (pattern surface) position of the mask M protected by the pellicle film, and the surface (exposure surface) position of the plate P. A position detecting device for the plate P is mounted.
[0022]
FIG. 2 is a diagram schematically illustrating a configuration of a position detection device that detects a surface position of a mask protected by a pellicle film. Referring to FIG. 2, the position detecting device for the mask M according to the present embodiment includes a light source 1 such as a halogen lamp. The light supplied from the light source 1 becomes almost parallel light through the collector lens 2 and sequentially enters the heat ray absorption filter 3, the first wavelength selection filter 4, and the second wavelength selection filter 5. Here, the heat ray absorbing filter 3 has a characteristic of absorbing light having a wavelength of, for example, 900 nm or more.
[0023]
The first wavelength selection filter 4 has a characteristic of blocking (cutting) transmission of light having a wavelength of, for example, 700 nm or less. The second wavelength selection filter 5 has a characteristic of cutting light having a wavelength of, for example, 800 nm or more. In this way, the light having a wavelength range of 700 nm to 800 nm selected by the action of the heat ray absorption filter 3, the first wavelength selection filter 4 and the second wavelength selection filter 5 passes through the condenser lens 6 and passes through a light guide such as an optical fiber. 7 is incident.
[0024]
The light propagating inside the light guide 7 and emitted from the emission end illuminates the slit illumination stop 9 via the condenser lens 8. The slit illumination stop 9 is disposed at a position optically substantially conjugate with the pattern surface of the mask M, and has a slit-like (elongate rectangular) opening (light transmission) elongated in a direction perpendicular to the paper surface of FIG. Part). The light that has passed through the opening of the slit illumination stop 9 passes through the aperture stop 10 arranged at a position optically substantially conjugate with the light source 1 and the objective lens 11 to form a pattern of the mask M protected by the pellicle film PR. The surface is Koehler-illuminated diagonally.
[0025]
In this way, the slit-like detection light flux elongated in the direction perpendicular to the paper surface of FIG. 2 is incident on the pattern surface of the mask M. Thus, the light source 1, the collector lens 2, the heat ray absorption filter 3, the first wavelength selection filter 4, the second wavelength selection filter 5, the condenser lens 6, the light guide 7, the condenser lens 8, the slit illumination stop 9, the aperture stop 10 , And the objective lens 11 constitute an irradiation system for irradiating the pattern surface of the mask M protected by the pellicle film PR with a slit-like detection light beam obliquely. At this time, the incident angle θ1 of the detection light beam is approximately 65 °. The incident angle θ1 is not limited to 65 °, but may be set in the range of 45 ° to 88 ° and 89 °.
[0026]
The reflected light from the mask M illuminated with the slit-like detection light beam passes through the objective lens 12 and the aperture stop 13 and has a light receiving surface having a detection surface arranged at a position optically substantially conjugate with the pattern surface of the mask M. Sensor 14 is reached. The light receiving sensor 14 photoelectrically detects a slit image formed so as to extend in a direction perpendicular to the paper surface of FIG. 2 on a detection surface thereof, and supplies a detection signal (photoelectric output) to the signal processing system 15. The signal processing system 15 detects the pattern surface position of the mask M along the optical axis of the projection optical system PL based on the slit image detection position.
[0027]
As described above, the objective lens 12, the aperture stop 13, the light receiving sensor 14, and the signal processing system 15 photoelectrically detect the detection light beam reflected by the pattern surface of the mask M, and based on the photoelectric output, detect the pattern surface of the mask M. It constitutes a detection system for detecting the position. Information on the pattern surface position of the mask M detected by the signal processing system 15 is supplied to the control system, and the mask stage MS is driven in accordance with a command from the control system, and thus the pattern of the mask M is placed on the object plane of the projection optical system PL. The plane is set.
[0028]
Note that the aperture stop 10 is arranged at the front focal position of the objective lens 11 so that the optical system in the irradiation system (1 to 11) is telecentric toward the mask M. The aperture stop 13 is disposed at the rear focal position of the objective lens 12 so that the optical system in the detection system (12 to 15) is telecentric toward the mask M.
[0029]
The position detecting device for the plate P has the same configuration as the position detecting device for the mask M. That is, in the position detecting device for the plate P, for example, the light emitted from the other branch emission end 21 of the light guide 7 illuminates the slit illumination stop 23 via the condenser lens 22. The light that has passed through the slit-shaped opening of the slit illumination stop 23 illuminates the exposure surface of the plate P obliquely through the aperture stop 24 and the objective lens 25. The incident angle θ2 of the detection light beam at this time is almost the same as the incident angle θ1 on the mask side, and is incident at an angle of about 65 °. The angle of incidence θ2 is not limited to 65 °, but may be in the range of 45 ° to 88 ° or 89 °.
[0030]
The reflected light from the plate P illuminated with the slit-like detection light flux reaches the light receiving sensor 28 via the objective lens 26 and the aperture stop 27. Thus, the position detecting device for the plate P detects the position of the exposure surface of the plate P along the optical axis of the projection optical system PL based on the position of the slit image formed on the detection surface of the light receiving sensor 28. Then, the plate stage PS is driven in accordance with a command from the control system to which information on the exposure surface position of the plate P is supplied, and the exposure surface of the plate P is set to the image surface of the projection optical system PL.
[0031]
FIG. 3 is a diagram showing the reflectance spectral characteristics of the pellicle film with respect to the vertically incident light (incident angle of 0 degree). FIG. 4 is a graph showing the spectral reflectance characteristics of the pellicle film with respect to oblique incident light (incident angle of 65 degrees). 3 and 4, the vertical axis indicates the reflectance (%), and the horizontal axis indicates the wavelength (nm). In FIG. 4, a thick solid line 41 indicates the reflectance for S-polarized light, and a thin solid line 42 indicates the reflectance for P-polarized light. Therefore, the reflectance for unpolarized obliquely incident light is between the thick solid line 41 and the thin solid line 42.
[0032]
Referring to FIG. 3, it can be seen that the reflectance of the pellicle film PR with respect to the vertically incident light is suppressed to be small in order to suppress the light amount loss of the exposure light due to the pellicle film PR. In particular, the reflectivity of a mercury lamp with respect to g-line (436 nm), h-line (405 nm) and i-line (365 nm) is suppressed to almost zero. On the other hand, referring to FIG. 4, since the pellicle film PR is configured so as not to substantially reflect the vertically incident light, it can be seen that the wavelength dependence of the reflectance with respect to the obliquely incident light is very large.
[0033]
FIG. 5 is a diagram illustrating spectral characteristics of the reflected light received by subtracting the loss of the pellicle film reflected light from the mask reflected light. In FIG. 5, the vertical axis indicates the magnitude of the amount of received and reflected light, and the horizontal axis indicates the wavelength (nm). In FIG. 5, a thick solid line 51 indicates a case where the thickness of the pellicle film PR is a standard value, a thin solid line 52 indicates a case where the thickness of the pellicle film PR is the largest within a tolerance, and a thin broken line 53 indicates a pellicle film PR. Is the smallest within the tolerance, and the thick broken line 54 indicates the case where the pellicle film PR is not interposed.
[0034]
In FIG. 5, a comparison between the thick solid line 51 and the thick broken line 54 indicates that periodic wavelength dependence occurs in the light reflected from the mask surface due to the reflectance spectral characteristics of the pellicle film PR. Further, when comparing the thick solid line 51 with the thin solid line 52 and the thin broken line 53, it can be seen that the wavelength dependence of the wavelength dependence of the reflected light from the mask surface changes with the variation in the thickness of the pellicle film PR. .
[0035]
FIG. 6 is a diagram showing a wavelength distribution characteristic of an LED widely used in the related art. In FIG. 6, the vertical axis indicates the relative radiation light intensity (%), and the horizontal axis indicates the wavelength (nm). 6, the solid line 61 indicates the wavelength distribution of the LED when there is no wavelength shift, the broken line 62 indicates the wavelength distribution of the LED when the maximum wavelength shift occurs on the minus side, and the dashed line 63 indicates the maximum wavelength shift on the plus side. The wavelength distribution of the LED when it occurs is shown. Referring to FIG. 6, it can be seen that the center wavelength of the LED is about 780 nm, the half width is about 30 nm, and the wavelength shift width is about 60 nm (about ± 30 nm).
[0036]
FIG. 7 is a diagram showing the spectral characteristics of the photoelectric output obtained by the light receiving sensor when the LED of the related art having the wavelength distribution characteristics of FIG. 6 is used. 7, the vertical axis indicates the photoelectric output level of the light receiving sensor, and the horizontal axis indicates the wavelength (nm). In FIG. 7, a thick solid line 71 indicates a photoelectric output level when there is no wavelength shift, a broken line 72 indicates a photoelectric output level when a maximum wavelength shift (−30 nm) occurs on the minus side, and a thin solid line 73 indicates a plus side. 2 shows the wavelength distribution of the LED when the maximum wavelength shift (+30 nm) occurs. In FIG. 7, it is assumed that the thickness of the pellicle film PR is a standard value, ignoring variations in the thickness of the pellicle film PR.
[0037]
Referring to FIG. 7, it can be seen that a relatively large photoelectric output level can be obtained in the light receiving sensor 14 in a standard state where no wavelength shift occurs in the LED. However, in the shift (−) state in which the maximum wavelength shift (−30 nm) occurs on the minus side, the loss of the pellicle film reflected light increases, and the photoelectric output level decreases to 以下 or less of the standard state. Further, in the shift (+) state where the maximum wavelength shift (+30 nm) occurs on the plus side, the loss of the pellicle film reflected light is further increased, and the photoelectric output level is reduced to 1/3 or less of the standard state.
[0038]
FIG. 8 is a diagram corresponding to FIG. 7 and shows the photoelectric output level in each state when the photoelectric output level in the shift (+) state is normalized to 1. Referring to FIGS. 7 and 8, since the wavelength band of the prior art LED having the wavelength distribution characteristic of FIG. 6 is narrow and the wavelength band is apt to fluctuate due to the wavelength shift, it is assumed that the variation in the thickness of the pellicle film PR is ignored. Also, it can be seen that the level of the photoelectric output obtained when the reflected light from the pattern surface of the mask M is photoelectrically detected tends to be large due to the reflectance spectral characteristics of the pellicle film PR.
[0039]
Further, as shown in FIG. 5, a change in the reflectance spectral characteristic in the wavelength direction occurs with a variation in the thickness of the pellicle film PR. It is conceivable that the fluctuation of the output level is further increased. Of course, even if the wavelength shift does not occur, the reflectance spectral characteristic changes in the wavelength direction due to the variation in the thickness of the pellicle film PR as described above. As a result, a change in the photoelectric output level easily occurs.
[0040]
On the other hand, in the present embodiment, the pellicle film PR protects light having a wavelength range of 700 nm to 800 nm selected from white light supplied by the light source 1 such as a halogen lamp, that is, light that does not cause a wavelength shift. The pattern surface of the mask M is irradiated. In other words, in this embodiment, a wavelength range (100 nm) larger than one cycle (about 60 nm: one cycle in a wavelength range of 700 nm to 800 nm) of the reflectance spectral characteristic of the pellicle film PR for obliquely incident light shown in FIG. ) And the detection light flux whose wavelength band does not fluctuate without causing a wavelength shift is applied to the pattern surface of the mask M.
[0041]
As described above, the book using the detection light beam having a wavelength range wider than one cycle of the reflectance spectral characteristic of the pellicle film PR and causing no wavelength shift (that is, having a spectral characteristic according to the reflectance spectral characteristic of the pellicle film PR). In the embodiment, even if the reflectance spectral characteristic changes in the wavelength direction due to the variation in the thickness of the pellicle film PR, the wavelength range of the detection light flux is changed to the wavelength range where the reflectance of the pellicle film PR is relatively small. Since the wavelength range including the relatively large reflectance of the PR is included, the influence of the change in the wavelength direction in the reflectance spectral characteristic of the pellicle film PR on the variation in the photoelectric output level can be suppressed by the so-called averaging effect.
[0042]
FIG. 9 is a view for explaining the effect of the present embodiment corresponding to FIG. 8, and shows the photoelectric output level in each thickness state of the pellicle film. In FIG. 9, the standard state is a state where the film thickness of the pellicle film PR is a standard value, the film thickness (−) state is a state where the film thickness of the pellicle film PR is the smallest within the tolerance, and the film thickness (+) state is a state. The state where the thickness of the pellicle film PR is the largest within the tolerance is shown. In FIG. 9, the photoelectric output level in the film thickness (-) state is normalized to 1.
[0043]
As shown in FIG. 9, in the present embodiment, the variation range of the photoelectric output level due to the change in the wavelength direction of the reflectance spectral characteristic due to the variation in the thickness of the pellicle film PR is set to about 20 times the minimum value of the photoelectric output level. %. Incidentally, in the prior art shown in FIG. 8, even if the variation in the thickness of the pellicle film PR is ignored, the fluctuation range of the photoelectric output level becomes 200% or more of the minimum value of the photoelectric output level due to the influence of the wavelength shift of the LED. Has reached.
[0044]
As described above, the position detection device of the present embodiment stably and accurately detects the pattern surface position of the mask M protected by the pellicle film PR while suppressing the influence of the reflectance spectral characteristics of the pellicle film PR. can do. Therefore, in the exposure apparatus of the present embodiment, the position of the pattern surface of the mask M protected by the pellicle film PR can be detected stably and with high accuracy by using a position detecting device for the projection optical system PL. Good exposure can be performed by setting the mask M with high accuracy.
[0045]
In the above-described embodiment, the wavelength of the obliquely incident light is in the range of 700 nm to 800 nm, but may be in the wavelength band of 800 nm to 900 nm or 600 nm to 700 nm, or within the wavelength range of about 600 nm to 1 μm. Any wavelength range of 100 nm may be used. Further, the wavelength band may be selected so as to be 200 nm or 300 nm in a wider wavelength range.
[0046]
In the above-described embodiment, a halogen lamp is used as a light source. However, the present invention is not limited to this. For example, a light source that supplies light having a wide wavelength width, such as a white LED, may be used. Further, in the above-described embodiment, one wavelength light is used as the detection light flux. However, the present invention is not limited to this. The interval between the minimum center wavelength and the maximum center wavelength is one of the reflectance spectral characteristics of the pellicle thin film PR. It is also possible to use a detection light beam including a plurality of wavelength lights set to be longer than the period. Specifically, a plurality of LEDs having different emission wavelengths, for example, a red LED (center wavelength: 640 nm), a green LED (center wavelength: 520 nm), and a blue LED (center wavelength: 480 nm) are combined through an optical dichroic mirror and used. be able to.
[0047]
In this case, the interval between the center wavelength 480 nm of the blue LED which is the minimum center wavelength and the center wavelength 640 nm of the red LED which is the maximum center wavelength is set to be larger than one cycle of the reflectance spectral characteristic of the pellicle thin film PR. Even if the center wavelength of each LED shifts and each wavelength band fluctuates, the above-described averaging effect can suppress the influence on the photoelectric output level fluctuation. Similarly, a mercury lamp or the like may be used as a light source, and a plurality of spectral lines, for example, g-line (436 nm), h-line (405 nm), and i-line (365 nm) may be used.
[0048]
In the above-described embodiment, a common light source is used for the position detection device for the mask M and the position detection device for the plate P, and light in the same wavelength band is used as a detection light beam. However, without being limited to this, the position detecting device for the mask M and the position detecting device for the plate P may use different light sources or may use light of different wavelength bands as the detection light flux. it can. However, in the position detecting device for the plate P, it is necessary to use light that does not expose the resist, for example, red light to infrared light (about 600 nm to 1 μm). Thus, for example, a position detector for the plate P uses red light to infrared light (about 600 nm to 1 μm), and a position detector for the mask M emits ultraviolet light (exposure wavelength) to visible light (about 400 nm to 500 nm). It can also be used.
[0049]
In the above-described embodiment, separate light receiving sensors are used for the position detecting device for the mask M and the position detecting device for the plate P. However, the present invention is not limited to this. The reflected light from the plate P is guided to a common light receiving sensor, and the pattern surface position of the mask M and the exposure surface position of the plate P can be detected based on the output of the common light receiving sensor.
[0050]
In the above-described embodiment, the present invention is applied to an exposure apparatus including one projection optical system. However, the present invention is not limited to this. For example, in an exposure apparatus having a plurality of partial projection optical systems arranged in a staggered manner as disclosed in Japanese Patent Application Laid-Open No. 7-57986, the field of view of each projection optical system A plurality of position detecting devices for detecting the pattern surface position of the mask M at the center may be provided.
[0051]
In the exposure apparatus of the above-described embodiment, the mask (reticle) is illuminated by the illumination device (illumination step), and the transfer pattern formed on the mask is exposed on the photosensitive substrate using the projection optical system (exposure step). Thereby, a micro device (semiconductor element, image pickup element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. Hereinafter, when a predetermined pattern (circuit pattern, electrode pattern, etc.) is formed on a plate (glass substrate) as a photosensitive substrate using the exposure apparatus of the present embodiment, a liquid crystal display element as a micro device is obtained. An example of the technique will be described with reference to the flowchart of FIG.
[0052]
In FIG. 10, in a pattern forming step 401, a so-called photolithography step of transferring and exposing a mask pattern onto a photosensitive substrate (a glass substrate coated with a resist or the like) using the exposure apparatus of the present embodiment is executed. By this photolithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. Thereafter, the exposed substrate undergoes each of a developing process, an etching process, a resist stripping process, and the like, whereby a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming process 402.
[0053]
Next, in the color filter forming step 402, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix, or three sets of R, G, B Are formed in a horizontal scanning line direction to form a color filter. Then, after the color filter forming step 402, a cell assembling step 403 is performed. In the cell assembly step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step 401, the color filter obtained in the color filter formation step 402, and the like.
[0054]
In the cell assembling step 403, for example, a liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern forming step 401 and the color filter obtained in the color filter forming step 402, and a liquid crystal panel (liquid crystal cell) is formed. ) To manufacture. Thereafter, in a module assembling step 404, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display device, a liquid crystal display device having an extremely fine circuit pattern can be obtained with high throughput. Similarly, a semiconductor device or the like as a micro device can be obtained by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of the present embodiment.
[0055]
In the above-described embodiment, the present invention is applied to the position detecting device for detecting the pattern surface position of the mask protected by the pellicle film in the exposure device, but the present invention is not limited to this. The present invention can also be applied to a general position detection device that detects the surface position of a substrate covered at an interval.
[0056]
【The invention's effect】
As described above, the position detection device of the present invention can stably and accurately detect the surface position of a mask protected by a pellicle film while suppressing the influence of the reflectance spectral characteristics of the pellicle film, for example. it can. Therefore, in the exposure apparatus and the exposure method according to the present invention, the position of the mask protected by the pellicle film can be detected stably and with high accuracy by using the position detection device, and the mask is projected to the projection optical system. Good exposure can be performed with high accuracy, and a good device can be manufactured by good exposure.
[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 device that detects a surface position of a mask protected by a pellicle film.
FIG. 3 is a diagram illustrating reflectance spectral characteristics of a pellicle film with respect to vertically incident light (incident angle of 0 degree).
FIG. 4 is a diagram showing the reflectance spectral characteristics of a pellicle film with respect to obliquely incident light (incident angle of 65 degrees).
FIG. 5 is a diagram illustrating the spectral characteristics of the reflected light received by subtracting the loss of the pellicle film reflected light from the mask reflected light.
FIG. 6 is a diagram showing a wavelength distribution characteristic of an LED widely used in the related art.
7 is a diagram showing spectral characteristics of photoelectric output obtained by a light receiving sensor when a conventional LED having the wavelength distribution characteristic of FIG. 6 is used.
8 is a diagram corresponding to FIG. 7 and shows the photoelectric output level in each state when the photoelectric output level in the shift (+) state is normalized to 1; FIG.
FIG. 9 is a diagram for explaining the effect of the present embodiment corresponding to FIG. 8 and shows the photoelectric output level in each thickness state of the pellicle film.
FIG. 10 is a flowchart of a method for obtaining a liquid crystal display element as a micro device.
[Explanation of symbols]
Illumination system for IL exposure
M mask
MS mask stage
PL projection optical system
P plate
PS plate stage
PR pellicle membrane
1 light source
2 Collector lens
3 Heat absorption filter
4,5 wavelength selective filter
6,8 Condenser lens
7 Light Guide
9 Slit illumination diaphragm
10,13 aperture stop
11,12 Objective lens
14 Light receiving sensor
15 Signal processing system

Claims (7)

In a position detection device that detects the surface position of the substrate covered at a distance by the thin film,
An irradiation system for irradiating the detection light beam obliquely to the surface of the substrate,
The detection light beam reflected on the surface of the substrate photoelectrically detected, comprising a detection system for detecting the surface position of the substrate based on the photoelectric output,
The position detection device according to claim 1, wherein the irradiation system irradiates a surface of the substrate with a detection light beam having a spectral characteristic according to a reflectance spectral characteristic of the thin film in order to suppress an influence caused by the thin film. The position detecting device according to claim 1, wherein the detection light beam has a required spectral characteristic for suppressing a level change of the photoelectric output caused by the thin film. 3. The position detecting device according to claim 1, wherein the irradiation system irradiates a surface of the substrate with a detection light flux having a wavelength range larger than one cycle of the reflectance spectral characteristic of the thin film. 4. The irradiation system may be configured to irradiate a surface of the substrate with a detection light beam including a plurality of wavelength lights in which an interval between a minimum center wavelength and a maximum center wavelength is set to be longer than one cycle of the reflectance spectral characteristic of the thin film. The position detecting device according to claim 1 or 2, wherein In an exposure apparatus that illuminates a mask protected by a pellicle film and exposes a pattern formed on the mask onto a photosensitive substrate,
An exposure apparatus, comprising: the position detection device according to claim 1 for detecting a surface position of the mask. An exposure method for illuminating a mask protected by a pellicle film and exposing a pattern formed on the mask onto a photosensitive substrate,
An exposure method comprising a step of detecting a surface position of the mask using the position detection device according to any one of claims 1 to 4. An exposure method for illuminating a mask protected by a pellicle film and exposing a pattern formed on the mask onto a photosensitive substrate,
On the surface of the mask protected by the pellicle film, obliquely irradiate a light beam having spectral characteristics to suppress the influence of the reflectance spectral characteristics of the pellicle film,
An exposure method comprising detecting reflected light from the surface due to the irradiation and measuring the position of the surface of the mask.

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