Detection apparatus, lithography apparatus, and method for manufacturing an article - Patent Application 20070122997

Abstract

To provide a technique advantageous for combining inspection accuracy and throughput when detecting a position of an inspection target.SOLUTION: A detection device for detecting a position of a detection target having a diffraction grating pattern includes: an illumination unit that illuminates the detection target with illumination light containing a plurality of wavelengths; a wavelength selection unit having an incident surface on which light diffracted by the illuminated detection target and selecting light of a specific wavelength from the diffracted light; and a detection unit that detects the position of the detection target by receiving light of the specific wavelength selected by the wavelength selection unit. On the incident surface of the wavelength selection unit, a plurality of elements for switching light guide / non-light guide of the diffracted light to the detector are arranged two-dimensionally, the wavelength selection unit controls the plurality of elements according to the position on which the light of the specific wavelength is incident on the incident surface, and among the diffracted light, the light of the specific wavelength is selected to guide to the detection unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a detection apparatus, a lithographic apparatus, and a method for manufacturing an article. [Background technology]

[0002] Lithography apparatuses such as projection exposure apparatuses and imprint apparatuses are used in the manufacture of articles such as semiconductor devices. In a projection exposure apparatus, a shot area on a substrate is aligned with an original (reticle), and the pattern of the original is projected onto the shot area of ​​the substrate via a projection optical system, thereby forming a latent image pattern in a photoresist applied to the substrate. A physical pattern is formed on the substrate by developing the latent image pattern. In an imprint apparatus, an imprint material is placed on the shot area of ​​the substrate, and the imprint material is cured while in contact with the original (mold), thereby forming a pattern made of the cured imprint material on the substrate.

[0003] When aligning a shot area on a substrate with an original, the relative positions of the shot area and the original are detected. This detection can be performed by detecting the relative positions of a mark provided in the shot area and a mark provided on the original. In a projection exposure apparatus, for example, a box-in-box may be formed by a mark on the substrate side and a mark on the original side. In an imprint apparatus, for example, a moiré fringe may be formed by a mark on the substrate side and a mark on the original side. Patent Document 1 describes evaluating detection errors resulting from a mark detection system and optimizing illumination conditions (e.g., illumination method such as illumination numerical aperture, or illumination wavelength) based on the evaluation results.

[0004] Here, if a detection target such as a mark has an asymmetric shape due to manufacturing error (processing error), an error may occur in the detection result of the mark position information. Such an error is called WIS (Wafer Induced Shift). Patent Document 2 describes that, in order to reduce WIS, the intensity of each of the light beams with multiple wavelengths in the illumination light is adjusted based on wavelength characteristics that indicate the relationship between the wavelength of the light illuminating the detection target and the detection error of the detector, so that the detection error of the detector is reduced. Patent Document 2 adjusts the intensity of each of the light beams with multiple wavelengths contained in the illumination light by adjusting the output of each of multiple light sources (semiconductor lasers) that emit light beams with different wavelengths. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-59853 [Patent Document 2] Japanese Patent Application Laid-Open No. 2019-4143 Summary of the Invention [Problem to be solved by the invention]

[0006] The detection error of the detector may vary depending on the position on the substrate where the detection target, such as a mark, is provided. Therefore, it is preferable to change the wavelength of light used to detect the position of the detection target depending on the position on the substrate where the detection target is provided, so as to reduce the detection error. However, when adjusting the output of each of multiple light sources (semiconductor lasers), as in the method described in Patent Document 2, it takes a considerable amount of time for the output of each light source to stabilize, which may be disadvantageous in terms of throughput (productivity).

[0007] Therefore, an object of the present invention is to provide an advantageous technique for achieving both high detection accuracy and high throughput when detecting the position of a detection target. [Means for solving the problem]

[0008] In order to achieve the above object, one aspect of the present invention provides a detection device for detecting the position of a detection target having a diffraction grating pattern, the detection device comprising: an illumination unit that illuminates the detection target with illumination light including a plurality of wavelengths; a wavelength selection unit that has an incident surface onto which diffracted light from the detection target illuminated by the illumination unit is incident and that selects light of a specific wavelength from the diffracted light; and a detection unit that receives the light of the specific wavelength selected by the wavelength selection unit and detects the position of the detection target, wherein the incident surface of the wavelength selection unit has a plurality of elements that are two-dimensionally arranged, each of which switches between guiding and not guiding the diffracted light to the detection unit, and the light of the multiple wavelengths included in the illumination light has different diffraction directions at the detection target and is incident at different positions on the incident surface of the wavelength selection unit as the diffracted light, and the wavelength selection unit selects the light of the specific wavelength from the diffracted light and guides it to the detection unit by controlling each of the plurality of elements in accordance with the position at which the light of the specific wavelength is incident on the incident surface. The wavelength selection unit identifies wavelengths at which the target cannot be detected based on information indicating a relationship between each of the plurality of wavelengths and a detection error in the detection unit, and determines the specific wavelengths in a wavelength band excluding the identified wavelengths so that the detection error is reduced. It is characterized by:

[0009] Further objects and other aspects of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings. [Effects of the Invention]

[0010] According to the present invention, for example, it is possible to provide an advantageous technique for achieving both high detection accuracy and high throughput when detecting the position of a detection target. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an imprint apparatus; [Figure 2] A diagram showing an example of the configuration of a position detector [Figure 3] A diagram showing an example of the configuration of a position detector [Figure 4] Diagram for explaining diffracted light [Figure 5] A diagram for explaining diffracted light [Figure 6]Diagram for explaining wavelength selection by the wavelength selection unit (liquid crystal filter) [Figure 7] A diagram showing the relationship between the pupil intensity distribution of the illumination optical system and the numerical aperture NAo of the detection optical system. [Figure 8] FIG. 10 is a diagram showing an example of the configuration of a diffraction grating as a mark. [Figure 9] FIG. 10 is a diagram showing an example of the configuration of a diffraction grating as a mark. [Figure 10] Diagram explaining the principle of detecting moiré fringes [Figure 11] Diagram explaining the principle of detecting moiré fringes [Figure 12] Diagram for explaining the cross-sectional structure of the mark (detection target) [Figure 13] FIG. 1 is a diagram for explaining the relationship between the wavelength of illumination light and detection error. [Figure 14] Flowchart showing how a particular wavelength is determined [Figure 15] A diagram showing the wavelength distribution (color distribution) of light incident on the entrance surface of a liquid crystal filter [Figure 16] Diagram for explaining wavelength selection by the wavelength selection unit (DMD) [Figure 17] A diagram for explaining a method for manufacturing an article. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0013] In the following embodiments, an imprint apparatus that forms a pattern of an imprint material on a substrate using a mold as an original will be described as an example of a lithography apparatus to which the detection apparatus according to the present invention is applied. However, the detection apparatus according to the present invention can also be applied to other lithography apparatuses, such as a projection exposure apparatus that exposes a substrate by projecting a pattern of a reticle (mask) as an original onto the substrate via a projection optical system.

[0014] First Embodiment A first embodiment of the present invention will be described. FIG. 1 shows an example of the configuration of an imprinting apparatus 1 according to this embodiment. The imprinting apparatus 1 brings an imprinting material 9 supplied onto a substrate 8 into contact with a mold 7 (pattern region 7a) and applies curing energy to the imprinting material 9, thereby forming a pattern of a cured product to which the recessed and raised pattern of the mold 7 has been transferred. Specifically, the imprinting apparatus 1 deposits the imprinting material 9 on the substrate 8 as multiple droplets, and then hardens the imprinting material 9 by irradiating it with light or the like while the mold 7 (pattern region 7a) having the recessed and raised pattern is brought into contact with the imprinting material 9 on the substrate 8. The distance between the mold 7 and the substrate 8 is then widened to separate (peel) the mold 7 from the cured imprinting material 9, thereby transferring the pattern of the mold 7 to the imprinting material 9 on the substrate, thereby forming a pattern on the substrate made of the cured imprinting material 9. This series of processes is called an "imprinting process," and is performed for each of multiple shot regions on the substrate.

[0015] The mold 7 is made of a material, such as quartz, that transmits light (e.g., ultraviolet light) for curing the imprint material 9, and a concave-convex pattern to be transferred to the imprint material 9 on the substrate 8 is formed in a partial region (pattern region 7a) on the surface facing the substrate. The pattern region 7a has a mesa shape with steps of, for example, several tens of μm. The substrate 8 may be made of, for example, glass, ceramics, metal, semiconductor, resin, or the like. If necessary, a member made of a material different from the substrate may be provided on the surface of the substrate 8. In this embodiment, the substrate 8 is, for example, a silicon wafer, a compound semiconductor wafer, or quartz glass.

[0016] The imprint material is a curable composition (sometimes referred to as an uncured resin) that cures when curing energy is applied. Examples of curing energy include electromagnetic waves and heat. Electromagnetic waves can be, for example, light with a wavelength selected from the range of 10 nm to 1 mm, such as infrared light, visible light, and ultraviolet light. The curable composition can be a composition that cures when irradiated with light or when heated. Among these, photocurable compositions that cure when irradiated with light contain at least a polymerizable compound and a photopolymerization initiator and may further contain a non-polymerizable compound or solvent, as needed. The non-polymerizable compound is at least one selected from the group consisting of sensitizers, hydrogen donors, internal mold release agents, surfactants, antioxidants, and polymer components. The imprint material can be arranged on the substrate in the form of droplets, or in the form of islands or films formed by connecting multiple droplets. The viscosity of the imprint material (at 25°C) can be, for example, 1 mPa·s to 100 mPa·s.

[0017] In this specification and the accompanying drawings, directions are indicated in an XYZ coordinate system, with the direction parallel to the surface of the substrate 8 being the XY plane. The directions parallel to the X, Y, and Z axes in the XYZ coordinate system are the X direction, Y direction, and Z direction, respectively, and rotation around the X axis, Y axis, and Z axis are referred to as θX, θY, and θZ, respectively. Control or drive about the X, Y, and Z axes refers to control or drive about the direction parallel to the X axis, the direction parallel to the Y axis, and the direction parallel to the Z axis, respectively. Control or drive about the θX, θY, and θZ axes refers to control or drive about rotation around an axis parallel to the X axis, the axis parallel to the Y axis, and the axis parallel to the Z axis, respectively. Position refers to information that can be determined based on coordinates of the X, Y, and Z axes, and orientation refers to information that can be determined by values ​​of the θX, θY, and θZ axes. Positioning refers to controlling the position and / or orientation. The alignment may include controlling the position and / or attitude of at least one of the substrate 8 and the mold 7 .

[0018] [Configuration of imprint device] The following provides an exemplary description of the configuration of the imprint apparatus 1. The imprint apparatus 1 may include a curing unit 2, a position detector 3, a mold driving mechanism 4, a substrate driving mechanism 5, a dispenser (imprint material supply unit) 6, and a control unit 15. The control unit 15 is configured by a computer having a processor such as a CPU and a memory, and controls the imprint process by controlling the curing unit 2, the position detector 3, the mold driving mechanism 4, the substrate driving mechanism 5, and the dispenser 6. The control unit 15 may be configured, for example, by a PLD (abbreviation for Programmable Logic Device) such as an FPGA (abbreviation for Field Programmable Gate Array), an ASIC (abbreviation for Application Specific Integrated Circuit), a general-purpose computer with an embedded program, or a combination of all or part of these.

[0019] After a contact step in which the imprint material 9 on the substrate 8 is brought into contact with the mold 7, the curing unit 2 irradiates the imprint material 9 with energy for curing the imprint material, thereby curing the imprint material 9. The curing unit 2 may include, for example, a light source that generates light for curing the imprint material 9. The light source may be, for example, a high-pressure mercury lamp, various excimer lamps, an excimer laser, or a light-emitting diode. As described above, the mold 7 has a pattern region 7a, and a pattern is formed in the pattern region 7a by recesses. With the imprint material 9 on the substrate 8 and the pattern region 7a of the mold 7 in contact, the imprint material 9 may fill the recesses in the pattern region 7a.

[0020] The substrate driving mechanism 5 can be configured to hold the substrate 8 and drive the substrate 8 about multiple axes (e.g., three axes: X-axis, Y-axis, and θZ-axis; preferably six axes: X-axis, Y-axis, Z-axis, θX-axis, θY-axis, and θZ-axis). The mold driving mechanism 4 can be configured to hold the mold 7 and drive the mold 7 about multiple axes (e.g., three axes: Z-axis, θX-axis, and θY-axis; preferably six axes: X-axis, Y-axis, Z-axis, θX-axis, θY-axis, and θZ-axis). The substrate driving mechanism 5 and the mold driving mechanism 4 constitute driving mechanisms that drive at least one of the substrate 8 and the mold 7 so as to adjust the relative positions of the substrate 8 and the mold 7. Adjustment of the relative positions by the driving mechanism includes driving the mold 7 to contact the imprint material 9 on the substrate 8 and to separate the mold 7 from the cured imprint material 9 (the pattern of the cured product).

[0021] In order to detect the relative position between the shot area of ​​the substrate 8 and the mold 7, the position detector 3 (detection device) detects the relative position of a mark 11 (second mark) provided in the shot area and a mark 10 (first mark) provided on the mold 7 as position information. Here, the marks 11 and 10 constitute a detection target for position information. The marks 11 and 10 may be marks that form moiré fringes, for example. In this case, the position detector 3 may detect the relative positions of the marks 11 and 10 as position information of the detection target based on the moiré fringes. Alternatively, the marks 11 and 10 may form a box-in-box mark. In this case, the position detector 3 may detect the positions of the marks 11 and 10 as position information of the detection target.

[0022] The position detector 3 includes an optical system for observing the mark, and the optical axis of the optical system can be arranged so as to be perpendicular to the surface of the substrate 8. The position detector 3 can be driven by a drive mechanism for positioning in the X and Y directions according to the position of the mark to be detected. The position detector 3 may also be driven in the Z direction for focus adjustment, and may include an optical system for focus adjustment.

[0023] Based on the position information detected by the position detector 3, the control unit 15 controls at least one of the substrate driving mechanism 5 and the mold driving mechanism 4 so that the shot area of ​​the substrate 8 and the mold 7 are aligned. The imprint apparatus 1 may also include a deformation mechanism that deforms the mold 7 to match the shape of the shot area of ​​the substrate 8 with the shape of the pattern area 7a of the mold 7. In this case, the control unit 15 can detect a difference in shape between the shot area and the pattern area 7a based on the multiple pieces of position information detected by the position detector 3, and control the deformation mechanism based on this shape difference.

[0024] The dispenser 6 deposits the imprint material 9 as multiple droplets on the shot area of ​​the substrate 8. The dispenser 6 can be configured to eject the imprint material 9 as multiple droplets at a timing according to a drop recipe while the substrate 8 is being driven by the substrate driving mechanism 5. The drop recipe is information (a map) that indicates the placement of multiple droplets of the imprint material 9 in the shot area. The dispenser 6 may be provided outside the imprint apparatus 1. In this case, the substrate 8 can be provided to the imprint apparatus 1 with the imprint material 9 deposited on it by the dispenser 6.

[0025] [Imprint processing] The imprint process performed by the imprint apparatus 1 will now be described. First, a substrate 8 is transported by a substrate transport mechanism (not shown) to a substrate holding section (not shown) of the substrate driving mechanism 5, and is held by the substrate holding section. Next, under the control of the control section 15, the substrate 8 is driven by the substrate driving mechanism 5 so that a shot area (hereinafter simply referred to as "shot area") of a pattern formation target (imprint target) is positioned under the dispenser 6. While the substrate 8 is being driven by the substrate driving mechanism 5, the dispenser 6 places an imprint material 9 on the shot area.

[0026] Next, under the control of the control unit 15, the substrate 8 is driven by the substrate driving mechanism 5 so that the shot area is positioned below the mold 7. Next, under the control of the control unit 15, at least one of the mold driving mechanism 4 and the substrate driving mechanism 5 is operated so that the imprint material 9 on the shot area comes into contact with the pattern area 7a of the mold 7.

[0027] Next, under the control of the control unit 15, the position detector 3 detects position information (relative position) between the shot area of ​​the substrate 8 and the pattern area 7a of the mold 7, and the shot area and the pattern area 7a are aligned based on this position information. The alignment between the shot area and the pattern area 7a can be performed by at least one of the substrate driving mechanism 5 and the mold driving mechanism 4. At this time, the mold 7 may be deformed by a deformation mechanism based on the difference in shape between the shot area and the pattern area 7a.

[0028] Next, under the control of the control unit 15, energy for curing is irradiated from the curing unit 2 onto the imprint material 9 via the mold 7, and the imprint material 9 is cured. Next, under the control of the control unit 15, at least one of the mold driving mechanism 4 and the substrate driving mechanism 5 is operated so as to separate the cured product of the imprint material 9 on the shot area from the pattern area 7a of the mold 7. As a result, a pattern made of the cured product of the imprint material 9 is formed on the shot area.

[0029] [Detector configuration example] The following describes an exemplary configuration of the position detector 3 (detection device). Fig. 2 shows an example configuration of the position detector 3. The position detector 3 can include an illumination optical system 31, a detection optical system 32, and a detection unit 33. In this embodiment, the illumination optical system 31 and the detection optical system 32 can be configured to share a portion.

[0030] The illumination optical system 31 includes a light source unit 31a that emits illumination light including multiple wavelengths (wavelength bands) and illuminates the detection target with the illumination light from the light source unit 31a. In the illumination optical system 31 of this embodiment, the illumination light from the light source unit 31a is guided onto the same optical axis as the detection optical system 32 using optical elements such as a prism 34, and the illumination light obliquely illuminates the marks 10 and 11, which are the detection targets. The light source unit 31a may be configured with a single light source that emits illumination light including multiple wavelengths, or may be configured with multiple light sources that emit light of different wavelengths. Examples of the light source included in the light source unit 31a include at least one of a supercontinuum light source, a halogen lamp, an LED, a semiconductor laser (LD), a plasma light source, a high-pressure mercury lamp, and a metal halide lamp. The illumination light may be light with a wavelength that does not cure the imprint material 9. Furthermore, the marks 10 and 11, which are the detection targets, may each be configured with a diffraction grating (i.e., may include a diffraction grating pattern).

[0031] The detection optical system 32 guides at least a portion of the diffracted light from the detection target (mark 10, mark 11) illuminated by the illumination optical system 31 (illumination unit) to the detection unit 33. The detection unit 33 receives at least a portion of the diffracted light guided by the detection optical system 32 and detects the position of the detection target. In this embodiment, the detection unit 33 may include an imaging element such as a CCD or CMOS image sensor. The detection optical system 32 forms moiré fringes (interference fringes) on the imaging surface of the imaging element (detection unit 33) due to interference of the diffracted light from each of the marks 10 and 11 illuminated by the illumination optical system 31. Because moiré fringes are formed by the diffracted light from the mark 10 on the mold 7 and the diffracted light from the mark 11 on the substrate 8, the amount of light in the moiré fringes may depend on the diffraction efficiency of the mold 7 and the substrate 8. In particular, because the diffraction efficiency varies depending on the wavelength, there are wavelengths at which moiré fringes can be efficiently detected and wavelengths at which moiré fringes are difficult to detect. Light with wavelengths at which moiré fringes are difficult to detect may become noise.

[0032] Here, the detection unit 33 may be understood as having a processing unit (processor) that determines the position of the detection target (i.e., the relative position between the marks 10 and 11) based on the image of the moiré fringes captured by the imaging element. The processing unit may also be understood as constituting part of the control unit 15. Furthermore, when the positions of the mold 7 and the substrate 8 are measured separately, the position detector 3 may be configured to detect only the mark 11 on the substrate 8 as exemplified in FIG. 3, or may be configured to detect only the mark 10 on the mold 7. For example, the position of the substrate 8 can be measured by detecting the position of the mark 11 on the substrate 8 with the position detector 3.

[0033] The prism 34 may be disposed on or near a pupil plane common to the illumination optical system 31 and the detection optical system 32. The prism 34 has a bonding surface, and a reflective film 34a for reflecting light from the peripheral portion of the pupil plane of the illumination optical system 31 may be provided on the bonding surface. The reflective film 34a also functions as an aperture stop that determines the pupil size (or detection NA: NAo) of the detection optical system 32. The prism 34 may be a half prism having a semi-transparent film on the bonding surface. Alternatively, a plate-shaped optical element having a reflective film formed on its surface may be used instead of a prism. Alternatively, the peripheral portion of the prism 34 in FIG. 2 may be a transmissive portion, and the central portion may be a reflective portion, with the positions of the light source unit 31a and the detection unit 33 (image sensor) interchanged.

[0034] The illumination optical system 31 and the detection optical system 32 each have an aperture stop 35, 36 on their pupil planes. The position of the aperture stop 36 in the detection optical system 32 (detection side) is conjugate with the position of the aperture stop 35 in the illumination optical system 31 (illumination side). Furthermore, a wavelength selection unit 80 is provided at the position of the aperture stop 36 in the detection optical system 32, which selects light of a specific wavelength from the diffracted light and guides it to the detection unit 33 (image sensor). The wavelength selection unit 80 has an incident surface 80a onto which the diffracted light from the detection target (marks 10 and 11) illuminated by the illumination optical system 31 is incident. Multiple elements are two-dimensionally arranged on the incident surface 80a, which switch between guiding and not guiding the diffracted light to the detection unit 33. As described above, the diffracted light from the detection target illuminated with illumination light having multiple wavelengths includes light of wavelengths at which moiré fringes can be efficiently detected and light of wavelengths at which moiré fringes are difficult to detect (i.e., light that may become noise). The wavelength selection unit 80 is configured to select light of a specific wavelength from the diffracted light, at which moiré fringes can be efficiently detected, and guide the selected light to the detection unit 33. In this embodiment (the example of FIG. 2), an example will be described in which the wavelength selection unit 80 uses an optical element in which a plurality of elements (pixels) that switch between transmitting and blocking the diffracted light are two-dimensionally arranged on an incident surface 80a. An example of the optical element is a liquid crystal filter 81.

[0035] 4 and 5 are diagrams illustrating diffracted light generated when the mark 10 on the mold 7 and the mark 11 on the substrate 8 are illuminated. When the diffraction grating patterns of the marks 10 and 11 are illuminated with illumination light containing multiple wavelengths (wavelength bands), diffracted light is generated at the marks 10 and 11. FIG. 4(a) illustrates first-order diffracted light. The multiple wavelengths of light contained in the illumination light have different diffraction directions (diffraction angles) depending on the wavelength, so the light can be wavelength-separated. Specifically, the longer the wavelength, the larger the angle of the diffracted light. As shown in FIG. 4(a), red light is reflected (diffracted) at a larger angle relative to the zero-order reflected light than violet light. Therefore, when the detection target (mark 10, mark 11) is obliquely illuminated with illumination light containing multiple wavelengths, the multiple wavelengths of light contained in the illumination light will be incident as diffracted light at different positions on the incident surface 80a of the wavelength selection unit 80, as shown in FIG. 5. Therefore, the wavelength selection unit 80 can select a specific light from the diffracted light and guide it to the detection unit 33 by controlling each of the multiple elements according to the position at which light of a specific wavelength is incident on the incident surface 80a. The lens 37 can be arranged on the optical path between the wavelength selection unit 80 and the detection target, and can be configured to direct light of multiple wavelengths diffracted by the detection target to different positions on the incident surface 80a of the wavelength selection unit 80. Oblique illumination of the detection target refers to illuminating the detection target with illumination light that is obliquely incident on the detection target. Light of a specific wavelength refers to, for example, light of a wavelength that allows efficient detection of moiré fringes, as described above.

[0036] The incident position of light of each wavelength on the incident surface 80a of the wavelength selection unit 80 is determined by the configuration of the position detector 3. Therefore, information (hereinafter sometimes referred to as first information) indicating the relationship between each of the multiple wavelengths included in the illumination light and the incident position of the light on the incident surface 80a can be obtained in advance by simulation, experiment, etc. As a result, the wavelength selection unit 80 can control each of the multiple elements to select light of a specific wavelength from the diffracted light and guide the light to the detection unit 33 based on the first information.

[0037] 4(b), even if the only object to be detected is mark 11 on substrate 8, it is possible to wavelength-divide the first-order diffracted light from mark 11 by selecting the pitch of the diffraction grating pattern of mark 11. Similarly, even if the only object to be detected is mark 10 on mold 7, it is possible to wavelength-divide the first-order diffracted light from mark 10 by selecting the pitch of the diffraction grating pattern of mark 10. In this embodiment, first-order diffracted light has been described, but the same applies when second-order, third-order, or higher-order diffracted light is used.

[0038] Next, an example of a configuration for detecting a detection target by obliquely illuminating it will be described with reference to FIG. 2. FIG. 2 shows an example in which the detection target (marks 10 and 11) is obliquely illuminated using an aperture stop 35. Marks 10 and 11 in FIG. 2 are marks for measuring the relative position in the Y direction between mold 7 and substrate 8, and Moiré fringes in the Y direction can be detected by illuminating marks 10 and 11 from a non-measurement direction (X direction). Furthermore, first-order diffracted light of the illumination light that has been wavelength-split by the detection target is incident on a liquid crystal filter 81 (incident surface 80a) serving as a wavelength selection unit 80, as exemplified in FIG. 2.

[0039] As described above, the liquid crystal filter 81 is composed of a plurality of elements (pixels), and each pixel can be selected to transmit or not transmit light (diffracted light). An example of the liquid crystal filter 81 is a liquid crystal element having a pixel count of 640 × 480 pixels. Under the control of the control unit 15, the wavelength selection unit 80 (liquid crystal filter 81) selects, for each pixel, whether to transmit incident light and guide it to the detection unit 33. That is, as shown in FIGS. 6( a) and 6(b), the wavelength selection unit 80 (liquid crystal filter 81) controls (switches) the transmission / non-transmission of each pixel so that light of a specific wavelength passes through, depending on the position at which light of the specific wavelength is incident on the incident surface 80a. This allows the specific light to be selected from the first-order diffracted light and guided to the detection unit 33.

[0040] 7 illustrates the relationship between the pupil intensity distributions (IL1 and IL2) of the illumination optical system 31 of the position detector 3 and the numerical aperture NAo of the detection optical system 32. The pupil intensity distribution of the illumination optical system 31 can include a first pole IL1 and a second pole IL2. When measuring the relative position between the mold 7 and the substrate 8 using a moiré fringe detection method, the first pole IL1 is the illumination for the X mark, and the second pole IL2 is the illumination for the Y mark. Furthermore, when measuring only the line-and-space diffraction grating pattern and not the moiré fringes, the diffracted light from the line-and-space diffraction grating pattern is diffracted in the measurement direction, so the first pole IL1 is the illumination for the Y mark, and the second pole IL2 is the illumination for the X mark.

[0041] Although the first pole IL1 and the second pole IL2 in FIG. 7 are shown positioned on the positive side of the Y direction and the positive side of the X direction, respectively, they may both be positioned on the negative side. It is also possible to use only the first pole IL1 or the second pole IL2. The aperture stop 35 is made of a metal plate or glass with a Cr film, and is positioned on the pupil plane of the illumination optical system 31. This allows the light from the light source unit 31a to form multiple poles (i.e., the first pole IL1 and the second pole IL2) and generate light rays (light beams) for obliquely illuminating the detection target. In other words, it is possible to block light rays from the light source unit 31a that are not used for measurement (i.e., light rays that may become noise). Furthermore, by changing the number of openings in the aperture stop 35, a monopole, dipole, or quadrupole can be formed. In this embodiment, to avoid interference between light wavelength-divided by marks 10 and 11, it is desirable to form a single pole in each of the X and Y directions, such as the first pole IL1 and the second pole IL2, as illustrated in FIG. 7. Light rays from the illumination optical system 31 pass through an aperture stop 35 and are reflected by a reflecting film 34 a of a prism 34 to obliquely illuminate the marks 10 and 11 .

[0042] [Moire fringe detection] Hereinafter, with reference to FIGS. 8(a) to 8(d), the principle of the generation of moiré fringes by diffracted light from mark 10 and mark 11, and detection of the relative position between mark 10 (mold 7) and mark 11 (shot area of ​​substrate 8) using moiré fringes will be described. A diffraction grating 41 shown in FIG. 8(a) can be provided on the mold 7 as mark 10, and a diffraction grating 42 shown in FIG. 8(b) can be provided on the substrate 8 as mark 11. The diffraction gratings 41 and 42 are marks for detecting the relative position between mark 10 (mold 7) and mark 11 (substrate 8) in the X direction, and the periods of their patterns (gratings) in the X direction, which is the detection direction, are slightly different. When two diffraction gratings 41 and 42 with different grating periods are overlapped, interference of the diffracted light from each of the two diffraction gratings causes moiré fringes to appear, which are patterns with a period reflecting the difference in period between the diffraction gratings. Since the phase of the moiré fringes changes depending on the relative positions of the diffraction gratings, the relative positions of marks 10 and 11, i.e., the relative positions of mold 7 and substrate 8 (shot areas thereof), can be determined by detecting the moiré fringes.

[0043] Specifically, when diffraction gratings 41 and 42, which have slightly different periods, are overlapped, the diffracted light from each of the diffraction gratings 41 and 42 overlap, generating moiré fringes having a period reflecting the difference in period, as illustrated in FIG. 8(c). The positions (phases) of the light and dark portions of the moiré fringes change depending on the relative positions of the diffraction gratings 41 and 42. For example, when one of the diffraction gratings 41 and 42 is shifted in the X direction, the moiré fringes illustrated in FIG. 8(c) may change to those illustrated in FIG. 8(d). Because the moiré fringes amplify the misalignment between the diffraction gratings 41 and 42 and appear as fringes with a large period, the relative positions of the diffraction gratings 41 and 42 can be detected with high accuracy even if the resolution of the detection optical system 32 (detection unit 33) is low. Here, in order to detect moiré fringes with high accuracy, it is desirable to illuminate the diffraction gratings 41 and 42 with oblique incidence (i.e., oblique illumination), detect the diffracted light diffracted in the vertical direction by the diffraction gratings 41 and 42 with the detection unit 33, and have a dark field configuration in which the zero-order light is not detected.

[0044] Light diffracted in the X direction by the diffraction gratings with slightly different periods enters the detection area (NAo) on the pupil of the detection optical system 32, carrying relative position information in the X direction, and is detected by the detection unit 33 (image sensor). This can be used to determine the relative positions of the two diffraction gratings. The detection unit 33 (image sensor) also forms an image from the received light, and can determine the relative position of the origin of the image and the offset of the mark.

[0045] Alternatively, one of the diffraction gratings 41 and 42 may be a checkerboard-shaped diffraction grating as shown in FIG. 9(a), and the other may be a diffraction grating as shown in FIG. 9(b). The diffraction grating illustrated in FIG. 9(b) includes a pattern periodically arranged in the detection direction and a pattern periodically arranged in a direction perpendicular to the detection direction. In the configurations shown in FIGS. 9(a) and 9(b), light from the first pole IL1 is incident on the diffraction grating and diffracted in both the Y and X directions by the checkerboard-shaped diffraction grating. Note that FIGS. 9(a) and 9(b) show marks (diffraction gratings) whose detection direction is the X direction, but marks (diffraction gratings) whose detection direction is the Y direction can also be configured in a similar manner. FIGS. 9(c) and 9(d) show marks (diffraction gratings) whose detection direction is the Y direction. The checkerboard-shaped diffraction gratings in FIGS. 9(a) and 9(c) are provided on one of the mold 7 and the substrate 8, and the line-and-space diffraction gratings in FIGS. 9(b) and 9(c) are provided on the other of the mold 7 and the substrate 8.

[0046] Here, the light from the second pole IL2 in the pupil intensity distribution shown in Fig. 7 is not used to detect the relative position of the diffraction grating shown in Fig. 9(a)-(b). However, when detecting the relative position of the diffraction grating shown in Fig. 9(c)-(d), the light from the second pole IL2 is used to detect the relative position of the diffraction grating, and the light from the first pole IL1 is not used to detect the relative position of the diffraction grating. Furthermore, when the set of diffraction gratings shown in Fig. 9(a)-(b) and the set of diffraction gratings shown in Fig. 9(c)-(d) are arranged in the same field of view of the detection optical system 32 (detection unit 33) to simultaneously detect relative positions in two directions, the pupil intensity distribution shown in Fig. 7 is advantageous.

[0047] Next, the principle of detecting moiré fringes by the detector 33 when the two marks 10 (checkerboard diffraction grating) and 11 (line-and-space diffraction grating) are superimposed will be described with reference to FIGS. 10 and 11.

[0048] Figure 10(a) shows the pitch of a checkerboard-shaped mark, and Figure 10(b) shows the pitch of a line-and-space-shaped diffraction grating. The checkerboard-shaped mark shown in Figure 10(a) has a pitch of P mm in the X direction and P mn in the Y direction, and the line-and-space-shaped mark shown in Figure 10(b) has a pitch of P w in the X direction. Note that the periods of the marks 10 in the X and Y directions may be the same, or may be different.

[0049] 11(a) is a diagram of marks 10 and 11, whose detection direction is the X direction, viewed from the X direction, and FIG. 11(b) is a diagram of marks 10 and 11 viewed from the Y direction. Moiré fringes for detecting the relative position in the X direction are generated by light from a first pole IL1 arranged on the Y axis in the illumination pupil plane shown in FIG. 7. Here, the diffraction angles φmn, φmm, and φw by the diffraction grating are expressed by the following equation (1), where λ is the wavelength of light and n is the diffraction order.

[0050] sinφmn=nλ / Pmn (1)

[0051] Therefore, if the diffraction angles by the marks 10 and 11 are φm and φw, respectively, the following formulas (2) and (3) are obtained. sinφmm=nλ / Pm (2) sinφw=nλ / Pw (3)

[0052] FIG. 11 illustrates the case where n=1. FIG. 11(a) is a diagram illustrating the YZ plane. FIG. 11(a) illustrates incident light from a first pole IL1 (hereinafter sometimes referred to as incident light IL1), specularly reflected light D0 of the incident light IL1, and diffracted light D1 from a mark 10 having a checkerboard diffraction grating. The diffracted light D1 is not a light beam reflected (diffracted) from the mark 10 of the mold 7, but a light beam reflected (diffracted) from the mark 11 of the substrate 8. This diffracted light D1 is detected by the detection unit 33.

[0053] Here, as shown in equation (1), the exit angle of diffracted light varies depending on the wavelength. The light split into wavelengths is Fourier transformed using a lens 37 or the like, and each wavelength is incident at a different position on the Fourier transform plane. In other words, information on the exit angle of the diffracted light can be converted into position information on the Fourier transform plane. In this embodiment, a wavelength selection unit 80 (liquid crystal filter 81) is disposed on the Fourier transform plane. As a result, as described above with reference to FIG. 5, light of multiple wavelengths contained in the diffracted light is incident at different positions on the incident surface 80a of the wavelength selection unit 80, and the wavelength selection unit 80 can select only light of a specific wavelength from the diffracted light.

[0054] Figure 11(b) is a diagram showing the XZ plane and illustrates the rays of the first-order diffracted light of incident light IL1. Diffracted lights D2 and D2' represent the ±1st-order light diffracted by mark 10, respectively, and diffracted lights D4 and D4' represent the ±1st-order light diffracted only by mark 11, respectively. Diffracted lights D3 and D3' represent light diffracted once by mark 10 and once by mark 11, respectively, and correspond to diffracted light D1 in Figure 11(a). Marks 10 and 11 have slightly different pitches in the X direction (detection direction). Therefore, the angle in the XY plane between diffracted light D3 generated by the +1st-order light at mark 10 and the −1st-order light at mark 11 and diffracted light D3' generated by the −1st-order light at mark 10 and the +1st-order light at mark 11 is slightly different, as indicated by φΔ in Figure 11(b). This slight angle difference (φΔ) generates a beat signal (Moiré fringes). For example, if the pitch of the diffraction grating pattern is Pmn = 4 μm, Pm = 1 μm, and Pw = 1.04 μm, the period of the moiré fringes is Pm × Pw / (Pw - Pm) / 2 = 13 μm. Note that the pitch of the diffraction grating pattern is not limited to the above value and can be determined taking into account the size of the mark.

[0055] [Detection error in the detector] The detection error in the position detector 3 (detection unit 33) will be described below. FIGS. 12(a) and 12(b) are diagrams for illustratively explaining the cross-sectional structure of a mark (detection target). In the example of FIGS. 12(a) and 12(b), the mark has a structure composed of three layers. These layers have steps, and when light is irradiated, the steps cause diffraction of light. Therefore, the mark can be recognized. The mark 11c illustrated in FIG. 12(a) is a mark without a shape error (manufacturing error). The mark 11d illustrated in FIG. 12(b) is a mark with an asymmetric shape error (manufacturing error). Since the mark 11c has a symmetric structure, the diffraction angle of the diffracted light is ideal. Therefore, no error occurs in the detected position of the mark. On the other hand, since the mark 11d has an asymmetric shape error, the diffraction angle of the diffracted light deviates from the ideal state by an amount corresponding to the asymmetry. Therefore, the detected position of the mark may have an error with respect to the actual position. In other words, the position detector 3 (detection unit 33) may have a detection error in the position of the mark. If this error is large, the overlay accuracy between layers of the substrate will decrease, which can lead to manufacturing defects.

[0056] The relationship between the wavelength of the illumination light of the position detector 3 and the detection error of the position detector 3 will be described with reference to FIGS. 13(a) and 13(b). Here, the detection error of the position detector 3 is a detection error that occurs when the mark 11 has an asymmetric shape (manufacturing error). FIG. 13(a) illustrates the cross-sectional shapes of the mark 11 on the substrate 8 and the mark 10 on the mold 7 when the mold 7 (pattern area 7a) and the substrate 8 (shot area) are brought into contact with each other via an imprint material 9. FIG. 13(b) illustrates the results of a simulation of the cross-sectional shape illustrated in FIG. 13(a) (wavelength characteristics (second information) indicating the relationship between each of the multiple wavelengths included in the illumination light of the position detector 3 and the detection error of the position detector 3).

[0057] In this simulation, the mark 11 is configured with a checkerboard diffraction grating pattern, with a step 52 of 200 nm, a pitch 51 of 1000 nm, and a shape error 53 of 40 nm. The substrate 8 is configured as a silicon substrate, and the mark 11 is configured of SiO2. A mold 7 is placed on the mark 11 with an imprint material 9 interposed therebetween.

[0058] Figure 13(b) shows the simulation results (wavelength characteristics). The horizontal axis of Figure 13(b) represents the wavelength of light used to detect the mark, and the vertical axis represents the detection error. The detection error on the vertical axis is the detection error of the position detector 3 (detection error of the relative position between marks 10 and 11) caused by the asymmetric shape of mark 11. As shown in Figure 13(b), the detection error of the position detector 3 varies depending on the wavelength of light. For example, marks cannot be detected in the wavelength range of 590 to 600 nm. Therefore, this wavelength range should not be used. Furthermore, wavelengths of 540 nm and 650 nm are wavelengths where detection error is small. Around these wavelengths, marks can be detected stably even if there is some error in the mark shape. In other words, the detection error of the position detector 3 can be reduced. Therefore, it is recommended to actively use light of this wavelength (near 540 nm or 650 nm) as the light of the specific wavelength mentioned above to detect marks.

[0059] [How to determine a specific wavelength] A method for determining a specific wavelength to be selected by the wavelength selection unit 80 (liquid crystal filter 81) of the position detector 3 will be described below with reference to FIG. 14. FIG. 14 is a flowchart illustrating the method for determining a specific wavelength. Each step in the flowchart of FIG. 14 can be controlled by the control unit 15. In FIG. 14, steps S101 to S103 are steps for forming a test sample. Step S104 is a step for detecting the relative positions of the marks 10 and 11 using the position detector 3 while changing the wavelength to be detected using the test sample, thereby obtaining wavelength characteristics related to the test sample. The wavelength characteristics are information (second information) indicating the relationship between each of the multiple wavelengths included in the illumination light and the detection error of the position detector 3 (detection unit 33). Step S105 is a step for determining a specific wavelength to be selected by the wavelength selection unit 80 and guided to the detection unit 33 based on the wavelength characteristics obtained in step S104. Step S106 is a step for storing information about the specific wavelength determined in step S105. Steps S101 to S106 are described in detail below.

[0060] In step S101, a substrate 8 having the same structure as a substrate for manufacturing an article is transported to a substrate holding portion of the substrate driving mechanism 5 and held by the substrate holding portion. Also in step S101, a mold 7 for manufacturing an article is transported to a mold holding portion of the mold driving mechanism 4 and held by the mold holding portion. In step S102, a shot area on the substrate 8 where a test sample is to be formed is pre-aligned with a pattern area 7a on the mold 7. Pre-alignment can be performed, for example, by detecting the relative positions of marks 11 in one or more shot areas on the substrate 8 and marks 10 on the mold 7 with the position detector 3 while the substrate 8 and the mold 7 are spaced apart.

[0061] In step S103, first, the dispenser 6 places the imprint material 9 in a shot region on the substrate 8 where a test sample is to be formed. Next, in step S103, at least one of the mold driving mechanism 4 and the substrate driving mechanism 5 is driven so that the imprint material 9 comes into contact with the pattern region 7a of the mold 7. Next, in step S103, the position detector 3 detects the relative positions of the mark 11 in the shot region where the test sample is to be formed and the mark 10 on the mold 7, while aligning the shot region with the pattern region 7a on the mold 7. Here, the detection result by the position detector 3 may include a detection error due to the asymmetric shape of the mark 11 on the substrate 8. Next, in step S103, the curing unit 2 hardens the imprint material 9. As a result, a structure having a pattern made of the cured product of the imprint material 9 is formed on the shot region as a test sample.

[0062] The wavelength used for pre-alignment in step S102 may be the same as or different from the wavelength used for alignment during imprinting in step S103. During pre-alignment, an air layer is present between the substrate 8 and the mold 7, so the optimal wavelength for detection may differ from that during imprinting. In this case, accurate alignment can be achieved by changing the wavelength conditions between pre-alignment and imprinting.

[0063] In step S104, while the pattern formed by the cured product of the imprint material 9 is in contact with the pattern region 7a of the mold 7, the wavelength characteristics of the test sample formed in step S103 are acquired using the position detector 3. Specifically, the wavelength selection unit 80 (control unit 15) performs wavelength selection by controlling each of the multiple elements arranged on the incident surface 80a so that each of the multiple wavelengths (wavelength bands) of light included in the illumination light from the light source unit 31a is received (detected) as test light by the detection unit 33. Then, for each of the multiple wavelengths of light, the detection unit 33 is caused to detect the position of the test sample. For example, the wavelength selection unit 80 selects light of a first wavelength from the multiple wavelengths included in the illumination light and guides it to the detection unit 33, causing the detection unit 33 to detect the position of the test sample. Next, the wavelength selection unit 80 selects light of a second wavelength different from the first wavelength from the multiple wavelengths included in the illumination light and guides it to the detection unit 33, causing the detection unit 33 to detect the position of the test sample. In this way, the wavelength of the light selected by the wavelength selection unit 80 and guided to the detection unit 33 is changed, and the detection unit 33 detects the position of the test sample for each wavelength. This allows the wavelength characteristics shown in FIG. 13(b) to be obtained. Such wavelength characteristics may be obtained for each of multiple positions on the substrate (for example, each of multiple shot areas on the substrate). In this case, the wavelength selection unit may change a specific wavelength between multiple shot areas (between multiple areas) based on the wavelength characteristics obtained for each of the multiple shot areas. In this embodiment, a test sample is formed in steps S101 to S103, and the wavelength characteristics are obtained using the test sample in step S104. However, it is also possible to obtain the wavelength characteristics shown in FIG. 13(b) by the simulation described above.

[0064] In step S105, based on the wavelength characteristics obtained in step S104, a specific wavelength (wavelength selection condition) to be selected by the wavelength selection unit 80 of the position detector 3 when manufacturing an article using the mold 7 is determined. As described above, the specific wavelength refers to the wavelength of light that should be received by the detection unit 33 in order to efficiently detect Moiré fringes. The specific wavelength may be understood as a wavelength that can reduce detection errors of the detection unit 33 caused by the mark 11 having an asymmetric shape due to manufacturing errors. The specific wavelength is not limited to one wavelength, but may also be a wavelength band having a certain bandwidth. The wavelength band selected as the specific wavelength may be one continuous wavelength band or multiple wavelength bands that are separated from each other.

[0065] In step S106, information about the specific wavelength determined in step S105 is saved. The specific wavelength information can be saved in a storage unit (memory) of the control unit 15, but it may also be saved in a device provided external to the imprint apparatus 1. This allows the wavelength selection unit 80 (control unit 15) to select light of a specific wavelength from diffracted light from the detection target (mark 10, mark 11) based on the information and guide the selected light to the detection unit 33 when manufacturing an article using the mold 7. In other words, it is possible to accurately detect the relative positions (position information) of the marks 10 and 11 while reducing detection errors of the detection unit 33 that are caused by the mark 11 having an asymmetric shape due to manufacturing errors.

[0066] Here, a supplementary explanation will be given regarding step S104. The wavelength of light detected by the detection unit 33 as test light can be selected by controlling the light guide / non-light guide of each of the multiple elements (pixels) in the wavelength selection unit 80 based on the first information described above. When generating the wavelength characteristics (second information), it is preferable to change the wavelength of the test light selected by the wavelength selection unit 80 and received by the detection unit 33 in order from the short wavelength side or the long wavelength side. Furthermore, to perform stable measurements regardless of wafer manufacturing variations, multiple continuous wavelength bands that are deemed to be somewhat effective based on optical simulation results and comparison results with an external measurement device may be selected as the specific wavelengths.

[0067] To eliminate the start-up time required for stable oscillation, the light source unit 31a (light source) may be maintained in a state where stable oscillation is possible, or may be started up in a step prior to step S104, taking into account the time required for stabilization. Furthermore, since the wavelength band of the illumination light from the light source unit 31a is broad, a wavelength cut filter may be used to narrow the wavelength band before the diffracted light enters the wavelength selection unit 80. For example, by changing the combination of a short wavelength cut filter and a long wavelength cut filter, it is possible to generate test light having a desired wavelength band. Furthermore, by using a wavelength cut filter whose transmission band continuously changes depending on the incident position of the light, it is possible to precisely control the wavelength of the light entering the wavelength selection unit 80.

[0068] In the conventional method of changing the ratio of wavelengths in illumination light by changing the intensity of the light source itself of a specific wavelength of a semiconductor laser that mixes multiple wavelengths, it is necessary to wait until the light source stabilizes before starting detection, which takes a considerable amount of time. In reality, it is difficult to wait a long time after the imprint material 9 has hardened, so it is necessary to perform imprinting multiple times to detect the position of the detection target. However, in the method of selecting wavelengths using the wavelength selection unit 80 as in this embodiment, it is possible to switch wavelengths and detect the position of the detection target in several tens of milliseconds, so it is possible to efficiently acquire data (e.g., wavelength characteristics) by using the time after imprinting.

[0069] Furthermore, the asymmetry of the mark shape may vary depending on the position (e.g., each shot area) on the surface of the substrate 8. Therefore, it is preferable to switch the wavelength (i.e., specific wavelength) of light used to detect the position of the mark to be detected for each position on the surface of the substrate 8. In the conventional method of adjusting the output of each of the multiple light sources (semiconductor lasers) included in the light source unit 31a, it takes a considerable amount of time for the output of each light source to stabilize after adjusting the output. This makes it difficult to quickly switch the wavelength of light used to detect the position of the mark, which can be disadvantageous in terms of throughput (productivity). On the other hand, the position detector 3 of this embodiment can quickly switch the wavelength of light used to detect the position of the mark using the wavelength selection unit 80 (liquid crystal filter 81), which can be advantageous in terms of throughput. Furthermore, when generating wavelength characteristics (second information), the wavelength selection unit 80 can quickly switch the wavelength of the test light, significantly reducing the time required to generate the wavelength characteristics. Reducing the time required to generate wavelength characteristics in this way allows more mark positions to be detected within the same detection time, thereby reducing the time required to generate wavelength characteristics for each position on the surface of the substrate 8. That is, the time required to determine a specific wavelength for each position within the surface of the substrate 8 can be shortened.

[0070] Another method for shortening the time required to generate wavelength characteristics is to obtain some of the necessary information by interpolation. Another interpolation method involves fitting using simulation results based on a model with a structure similar to that of the test sample. For example, if simulation results such as those shown in Figure 13(b) are obtained, a function approximating Figure 13(b) can be calculated in advance, and this function can be used as the initial function for the fitting function to fit coefficients using data obtained by actual measurements. This allows for the creation of a graph with a trend consistent with the simulation results. The detection error for wavelengths not actually measured can then be calculated from this graph. Another effective method is to perform fitting by defining an initial fitting function based on past actual measurement results under similar process conditions, rather than using simulation results. This method allows for the reduction of errors relative to actual measurements, even with a reduced number of measurement points.

[0071] Furthermore, as described above, the wavelength characteristics can also be obtained by a simulation such as that described with reference to FIG. 13. The simulation may be performed by the control unit 15 or by using a computer connected to the control unit 15. In the simulation, it should be taken into consideration that a deviation occurs between the wavelength characteristics obtained by the simulation and the actual wavelength characteristics when the asymmetric shape of the mark changes. Such a deviation may cause an error in the position information detected using wavelength selection conditions (specific wavelengths) determined based on the wavelength characteristics.

[0072] Therefore, a method for reducing errors caused by such factors will be described. First, wavelength characteristics are obtained for multiple models. The multiple models are models with different asymmetric shapes (shape errors caused by manufacturing errors), and may be models with different thicknesses or inclinations of stacked layers, for example. Next, from the simulation results for the multiple models, the sensitivity of the detection error to shape errors is obtained for each wavelength. Next, the sensitivities obtained for the multiple models are added together, and multiple wavelengths with low sensitivity to shape errors are selected as detection wavelengths.

[0073] The example shown in FIG. 13(b) is the result of a simulation performed under the assumption that there is no alignment error between marks 10 and 11 (i.e., the positions of marks 10 and 11 are aligned). Therefore, a detection error of 0 nm corresponds to an alignment error of 0. When forming the test sample in step S103, a detection error may exist in the relative positions of marks 10 and 11 detected by the position detector 3 due to the asymmetric shape of mark 11. Therefore, an alignment error may also exist between the shot area of ​​substrate 8, which is aligned based on the relative positions of marks 10 and 11 detected by the position detector 3, and the mold 7. If an alignment error exists, detecting the relative positions of marks 10 and 11 using multiple wavelengths in that state results in a result in which an offset amount equivalent to the alignment error has been added to the graph in FIG. 12(b).

[0074] To determine the offset amount from the results detected by the position detector 3, it is necessary to know the correct relative positions (alignment error) between the marks 11 and 10. To do this, the alignment error of the test sample can be evaluated using an evaluation device such as an overlay inspection device. The control unit 15 obtains wavelength characteristics with the offset corrected based on the wavelength characteristics obtained by the above method and the evaluation results obtained using the evaluation device. If the simulation results shown in FIG. 13(b) are accurate, the corrected wavelength characteristics can be equivalent to the simulation results.

[0075] For example, if the alignment error between mark 11 on substrate 8 and mark 10 on mold 7 when producing a test sample is 100 nm, the position in Figure 13(b) where the detection error is 0 nm will actually be measured as a position offset by 100 nm. When the test sample is evaluated using an evaluation device such as an overlay inspection device, the overlay error (alignment error) will be evaluated as 100 nm.

[0076] Furthermore, in an imprint apparatus 1 equipped with a position detector 3 having the above configuration, the wavelength characteristics of a test sample can be obtained through steps S101 to S106 in the flowchart of Fig. 14. Here, the wavelength characteristics obtained by detecting the position information of the test sample with the position detector 3 can have an offset value corrected based on the evaluation results obtained using an evaluation device such as an overlay inspection device.

[0077] Next, a supplementary explanation will be given of step S105. As shown in the wavelength characteristics exemplified in Fig. 13(b), the detection error varies depending on the wavelength of the light received by the detection unit 33. The control unit 15 determines the wavelength selection conditions for the wavelength selection unit 80, more specifically, the specific wavelengths (wavelength bands) selected by the wavelength selection unit 80, so as to reduce the detection error of the position detector 3 (errors in the position information detected by the position detector 3).

[0078] Hereinafter, a control example for selecting a wavelength by the liquid crystal filter 81 serving as the wavelength selection unit 80 from illumination light generated by a white light laser light source (supercontinuum light source) constituting the light source unit 31a will be described. The liquid crystal filter 81 serving as the wavelength selection unit 80 is composed of a plurality of pixels (e.g., 640 × 480 pixels) arranged two-dimensionally on the incident surface 80a onto which diffracted light is incident, and each pixel can be turned ON or OFF individually. In other words, the ON / OFF of each pixel is controlled so that on the incident surface 80a of the liquid crystal filter 81, each pixel arranged at a position where light of a specific wavelength is incident transmits the light, and each pixel arranged at other positions does not transmit the light.

[0079] As described above, the liquid crystal filter 81 (wavelength selection unit 80) is disposed on the Fourier transform plane relative to the positions of the marks 10 and 11, and therefore light of different wavelengths reaches the liquid crystal filter 81 depending on the position on the incident surface 80. FIG. 15 schematically shows the wavelength distribution (color distribution) of light incident on the incident surface 80a of the liquid crystal filter 81 in the XY plane. The position at which light reaches the incident surface 80a of the liquid crystal filter 81 varies depending on the value of its wavelength λ. Therefore, by selecting whether to transmit or block light for each position on the incident surface 80a of the liquid crystal filter 81, it is possible to select the wavelength of light to be transmitted through the liquid crystal filter 81 and guided to the detection unit 33. Furthermore, as shown in FIGS. 6(a) and 6(b), the liquid crystal filter 81 can select either a discrete or continuous wavelength band to guide light to the detection unit 33 by determining whether the light transmission region is divided or continuous. FIG. 6(a) shows an example of selecting light in one continuous wavelength band, and FIG. 6(b) shows an example of selecting multiple (two) wavelength bands that are separated from each other.

[0080] As described above, the position detector 3 of this embodiment includes a wavelength selection unit 80 having an incident surface 80a on which a plurality of elements, each of which switches between guiding and not guiding diffracted light to the detection unit 33, are arranged two-dimensionally. The wavelength selection unit 80 controls each of the elements in the wavelength selection unit 80 according to the position at which a particular wavelength is incident on the incident surface 80a, thereby selecting light of a particular wavelength from the diffracted light and guiding it to the detection unit 33. The position detector 3 having such a wavelength selection unit 80 can quickly switch wavelengths according to the position on the substrate where the detection target is provided. Therefore, this configuration may be advantageous in terms of throughput (productivity) compared to conventional configurations in which wavelengths are selected by changing the output of the light source unit 31a.

[0081] Second Embodiment A second embodiment of the present invention will be described. In the first embodiment, an example in which a liquid crystal filter 81 is used as the wavelength selection section 80 is described. In the second embodiment, an example in which an optical element in which a plurality of elements (pixels) that switch between reflecting and non-reflecting diffracted light are two-dimensionally arranged on an incident surface 80a is used as the wavelength selection section 80 is described. An example of the optical element is a digital mirror device (DMD) 82. Note that the second embodiment basically follows on from the first embodiment, and is the same as that described in the first embodiment except for the matters described below.

[0082] In the position detector 3 of this embodiment, as illustrated in FIG. 3 , a digital micromirror device (DMD) 82 is used instead of the aperture stop 36 of the detection optical system 32, and the DMD 82 can function as the wavelength selector 80. The DMD 82 is composed of multiple elements (elements, mirrors), e.g., 640 × 480 elements, and each element can switch between reflecting and non-reflecting diffracted light. This allows each element of the DMD 82 to select whether or not to guide a light beam to the detector 33. Using the DMD 82 as the wavelength selector 80 has the advantage of higher diffraction efficiency compared to using a liquid crystal filter 81. In the configuration of FIG. 3 , the DMD 82 is disposed on the Fourier transform plane relative to the surface of the substrate 8, and light reflected by the DMD 82 is guided to the detector 33 (image sensor).

[0083] Here, wavelength division of illumination light will be described with reference to FIG. 4. As in the first embodiment, as shown in FIGS. 4(a) and 4(b), primary light of illumination light diffracted and wavelength-divided by marks 10 and 11 is incident on the DMD 82. Because the DMD 82 is disposed at the Fourier transform plane, the incident position on the incident surface 80a of the light incident on the DMD 82 differs depending on the wavelength. Therefore, as illustrated in FIGS. 16(a) and 16(b), by controlling the state of each element of the DMD 82, light of a specific wavelength can be selected from the diffracted light and guided to the detection unit 33. Under the control of the control unit 15, the DMD 82 selects for each element (mirror) of the DMD 82 whether or not to guide incident light to the detection unit 33.

[0084] The DMD 82 can change the optical path of reflected light by changing the orientation of each mirror element. Therefore, as shown in Figures 16(a) and 16(b), the DMD 82 as the wavelength selection unit 80 can select either a discrete or continuous wavelength band to be guided to the detection unit 33 as a specific wavelength, depending on whether the region that reflects light and guides it to the detection unit 33 is divided or continuous. Figure 16(a) shows an example in which light in one continuous wavelength band is selected and guided to the detection unit 33, while Figure 16(b) shows an example in which multiple (two) wavelength bands that are separated from each other are selected and guided to the detection unit 33.

[0085] As described above, in this embodiment, the DMD 82 is used as the wavelength selection unit 80. As in the first embodiment, this embodiment also allows for rapid wavelength switching depending on the position on the substrate where the detection target is located. Therefore, this can be advantageous in terms of throughput (productivity) compared to the conventional configuration in which the wavelength is selected by changing the output of the light source unit 31a.

[0086] <Embodiments of manufacturing methods of articles> The article manufacturing method according to the embodiment of the present invention is suitable for manufacturing articles such as microdevices, such as semiconductor devices, and elements having microstructures. The article manufacturing method according to the present embodiment includes a detection step in which a mark provided on a substrate is detected as a detection target using the position detector 3 described above and a positioning step in which the substrate is positioned based on the detection results from the detection step. The article manufacturing method according to the present embodiment also includes a processing step in which the substrate positioned in the positioning step is processed, and a manufacturing step in which the article is manufactured from the substrate processed in the processing step. The processing step may include a step of forming a pattern on the substrate using the lithography apparatus (imprint apparatus 1) described above. Furthermore, the manufacturing method may include other well-known processes (such as oxidation, film formation, deposition, doping, planarization, etching, resist stripping, dicing, bonding, and packaging). The article manufacturing method according to the present embodiment is advantageous over conventional methods in at least one of article performance, quality, productivity, and production cost.

[0087] When an imprinting apparatus is used as the lithography apparatus, the pattern of the cured product formed by the imprinting apparatus is used permanently on at least a portion of various articles, or temporarily when manufacturing various articles. Examples of articles include electrical circuit elements, optical elements, MEMS, recording elements, sensors, and molds. Examples of electrical circuit elements include volatile or non-volatile semiconductor memories such as DRAM, SRAM, flash memory, and MRAM, and semiconductor elements such as LSI, CCD, image sensors, and FPGAs. Examples of molds include molds for imprinting.

[0088] The pattern of the cured product may be used as it is as at least a part of a component of the article, or may be used temporarily as a resist mask, which is removed after etching or ion implantation in a substrate processing step.

[0089] Next, a specific method for manufacturing the article will be described. As shown in Figure 17(a), a substrate 1z such as a silicon wafer is prepared, on the surface of which a workpiece 2z such as an insulator is formed. Next, an imprint material 3z is applied to the surface of the workpiece 2z by an inkjet method or the like. Here, a state in which multiple droplets of the imprint material 3z have been applied to the substrate is shown.

[0090] As shown in Figure 17(b), an imprinting mold 4z is placed with its side on which the concave-convex pattern is formed facing the imprinting material 3z on the substrate. As shown in Figure 17(c), the substrate 1z to which the imprinting material 3z has been applied is brought into contact with the mold 4z, and pressure is applied. The imprinting material 3z fills the gap between the mold 4z and the workpiece 2z. In this state, when light is irradiated through the mold 4z as hardening energy, the imprinting material 3z hardens.

[0091] 17(d), after the imprint material 3z is cured, the mold 4z and the substrate 1z are separated, and a pattern of the cured imprint material 3z is formed on the substrate 1z. In this cured material pattern, the recesses of the mold correspond to the protrusions of the cured material, and the protrusions of the mold correspond to the recesses of the cured material, i.e., the recess-protrusion pattern of the mold 4z is transferred to the imprint material 3z.

[0092] As shown in Figure 17(e), when etching is performed using the cured material pattern as an etching-resistant mask, portions of the surface of the workpiece 2z where no cured material or only a thin layer remains are removed, forming grooves 5z. As shown in Figure 17(f), when the cured material pattern is removed, an article is obtained in which grooves 5z are formed in the surface of the workpiece 2z. Here, the cured material pattern is removed, but it may also be used as an interlayer insulating film included in a semiconductor device or the like, i.e., a component of an article, without being removed after processing.

[0093] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0094] 1: imprint device, 3: position detector, 7: mold, 8: substrate, 10: mark (mold side), 11: mark (substrate side), 15: control unit, 31: illumination optical system, 31a: light source unit, 32: detection optical system, 33: detection unit (image sensor), 37: lens, 80: wavelength selection unit

Claims

1. A detection device for detecting the position of a detection target having a diffraction grating pattern, an illumination unit that illuminates the detection target with illumination light including a plurality of wavelengths; a wavelength selection unit having an incident surface onto which diffracted light from the detection target illuminated by the illumination unit is incident, the wavelength selection unit selecting light of a specific wavelength from the diffracted light; a detection unit that receives light of the specific wavelength selected by the wavelength selection unit and detects the position of the detection target; Equipped with a plurality of elements each switching between guiding and not guiding the diffracted light to the detection unit are two-dimensionally arranged on the incident surface of the wavelength selection unit; the light beams of the plurality of wavelengths included in the illumination light are diffracted in different directions at the detection target and are incident as the diffracted light beams at different positions on the incident surface of the wavelength selection unit, the wavelength selection unit selects the light of the specific wavelength from the diffracted light by controlling each of the plurality of elements in accordance with a position on the incident surface at which the light of the specific wavelength is incident, and guides the selected light to the detection unit; The wavelength selection unit identifies wavelengths at which the target cannot be detected based on information indicating a relationship between each of the plurality of wavelengths and a detection error in the detection unit, and determines the specific wavelengths in a wavelength band excluding the identified wavelengths so that the detection error is reduced.

2. 2. The detection device according to claim 1, further comprising a lens between the wavelength selection unit and the detection object, which causes the light of the plurality of wavelengths diffracted by the detection object to be incident at different positions on the incident surface.

3. 3. The detection device according to claim 1, wherein the wavelength selection section includes an optical element that switches between transmission and non-transmission of the diffracted light in each of the plurality of elements.

4. 3. The detection device according to claim 1, wherein the wavelength selection section includes an optical element that switches between reflecting and non-reflecting the diffracted light in each of the plurality of elements.

5. 5. The detection device according to claim 1, wherein the illumination unit obliquely illuminates the detection target with the illumination light.

6. 6. The detection device according to claim 1, wherein the wavelength selection unit controls each of the plurality of elements to select light of the specific wavelength from the diffracted light and guide it to the detection unit based on information indicating a relationship between each of the plurality of wavelengths and an incident position on the incident surface.

7. 7. The detection device according to claim 1, wherein the wavelength selection unit obtains a detection error at the detection unit while changing a wavelength selected from the plurality of wavelengths, thereby generating information indicating a relationship between each of the plurality of wavelengths and the detection error at the detection unit.

8. the detection target has a plurality of regions whose positions are detected by the detection device; The detection device according to claim 1 , wherein the wavelength selection section changes the specific wavelength among the plurality of regions.

9. A detection device described in any one of claims 1 to 8, characterized in that the wavelength selection unit is a digital micromirror device.

10. 1. A lithographic apparatus for forming a pattern on a substrate, comprising: a detection device according to any one of claims 1 to 9, which detects a position of a mark provided on the substrate as a detection target; a mechanism for positioning the substrate based on the detection result of the detection device; 1. A lithographic apparatus comprising:

11. a detection step of detecting a position of a mark provided on a substrate by the detection device according to any one of claims 1 to 9; a positioning step of positioning the substrate based on the detection result in the detection step; a processing step of processing the substrate positioned in the positioning step; a manufacturing process for manufacturing an article from the substrate processed in the processing process; A method for manufacturing an article, comprising:

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