Position detection device and lithography device

Abstract

To provide a position detection device capable of shortening a time required for deriving an appropriate light reduction condition when receiving light with a light volume larger than a light receiving limitation of a sensor.SOLUTION: A position detection device includes: a light volume sensor for detecting light through a first mark disposed in a first member and a second mark disposed in a second member; and a detection section for performing relative position detection of the first member and the second member by using a result made by the light volume sensor which has detected light reduced based on a light reduction condition derived by an acquired light volume distribution as a light volume distribution of light detected by the light volume sensor, and a plurality of light volume distributions stored in a storage section.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a position detection apparatus and a lithography apparatus. [Background Art]

[0002] There is known a method of illuminating a target with light from a light source, receiving transmitted light or reflected light of the illuminated light with a sensor, and detecting the position of the target from the peak position of the light intensity distribution of the received light detected by the sensor. Further, there is a method of reducing the amount of light received by the sensor using a dimming means when the amount of light received by the sensor is large.

[0003] Here, when a light amount exceeding the upper limit of the light amount that can be received by the sensor (hereinafter referred to as the light reception limit) is received, the shape of the peak of the light intensity distribution is unclear, so the required dimming amount becomes unclear. To address this problem, Patent Document 1 discloses a method of deriving appropriate dimming conditions based on the number of pixels of a sensor that has received a light amount larger than the light reception limit. [Prior Art Document] [Patent Document]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2014-160696 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, in the method disclosed in Patent Document 1, when the number of pixels of the sensor that has received a light amount larger than the light reception limit is large, adjustment is performed to greatly reduce the light amount, so it may take time to derive appropriate dimming conditions.

[0006] Accordingly, an object of the present invention is to provide a position detection apparatus capable of reducing the time required to derive appropriate dimming conditions when a light amount larger than the light reception limit of a sensor is received. [Means for Solving the Problem]

[0007] To achieve the above objective, the position detection device, as one aspect of the present invention, uses light transmitted through a first mark provided on a first member and a second mark provided on a second member. Light reception A light intensity sensor, When the light intensity sensor receives light with an intensity greater than the light reception limit, The aforementioned light intensity sensor It receives light The light intensity sensor detects the attenuated light based on the attenuation conditions derived from the acquired light intensity distribution, which is the light intensity distribution of the light, and a plurality of light intensity distributions stored in the memory unit. Light reception The system includes a detection unit that uses the results to detect the relative positions of the first member and the second member. The plurality of light intensity distributions include a light intensity distribution that does not include a light intensity greater than the light-receiving limit, and the derived attenuation condition is derived based on the attenuation condition corresponding to the light intensity distribution that does not include a light intensity greater than the light-receiving limit, which corresponds to the optical conditions when the acquired light intensity distribution was acquired. It is characterized by the following:

[0008] Further objects or other aspects of the present invention will be revealed by embodiments described below with reference to the accompanying drawings. [Effects of the Invention]

[0009] According to the present invention, the time required to derive appropriate attenuation conditions when a light intensity greater than the sensor's light-receiving limit is detected can be reduced. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the configuration of the projection exposure apparatus in the first embodiment. [Figure 2] This is a schematic diagram illustrating how the light intensity sensor in the first embodiment detects light that has passed through a calibration mark and a reference mark. [Figure 3] This is an example of a light intensity distribution derived based on the light intensity detected by the light intensity sensor in the first embodiment. [Figure 4] This is an example of a light intensity distribution when the amount of light received by the light intensity sensor in the first embodiment is greater than the light reception limit. [Figure 5] This is an example of deriving the light intensity distribution for multiple attenuation conditions under a single optical condition in the first embodiment. [Figure 6] This is a flowchart for storing multiple light intensity distributions in the first embodiment. [Figure 7] This is a flowchart for deriving appropriate dimming conditions in the first embodiment. [Figure 8] This is an example of deriving a correction rate for the light intensity value, which indicates the rate of change in light intensity over time, in the first embodiment. [Figure 9] This is an example of deriving a correction rate for light intensity values ​​that encompasses two elements in the first embodiment: the rate of change in light intensity over time and the difference in light intensity due to differences in dimming conditions. [Figure 10] This is a flowchart of the method for manufacturing an article in the second embodiment. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the following embodiments do not limit the invention as defined in the claims. While multiple features are described in the embodiments, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the accompanying drawings, the same or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0012] Furthermore, in this specification and the accompanying drawings, directions are generally indicated by an XYZ coordinate system in which the axes are mutually orthogonal, with the Z-axis being the axis parallel to the optical axis of the projection optical system and the XY-plane being the horizontal plane perpendicular to the Z-axis. However, if an XYZ coordinate system is shown in each drawing, that coordinate system shall take precedence.

[0013] The specific configurations for each embodiment will be described below.

[0014] <First Embodiment> FIG. 1 is a schematic diagram showing the configuration of a projection exposure apparatus 100 according to the present embodiment. The projection exposure apparatus 100 is an exposure apparatus that exposes (transfers) a pattern of an original (mask, reticle) onto a substrate via a projection optical system, and is provided with a position detection apparatus 1. However, the apparatus provided with the position detection apparatus 1 is not limited to an exposure apparatus, and may be any apparatus that detects the position of a member within the apparatus. For example, the position detection apparatus 1 may be provided in a drawing apparatus that draws a pattern on a substrate with an electron beam, an ion beam, or the like to form the pattern on the substrate. The position detection apparatus 1 may also be provided in another lithography apparatus, for example, an imprint apparatus that molds an imprint material on a substrate with a mold to form a pattern on the substrate. Alternatively, the position detection apparatus 1 may be provided in another apparatus that processes substrates such as wafers and glass, such as an ion implantation apparatus, a developing apparatus, an etching apparatus, a film forming apparatus, an annealing apparatus, a sputtering apparatus, or a vapor deposition apparatus. The position detection apparatus 1 may also be provided in a planarization apparatus that planarizes a composition on a substrate using a flat plate.

[0015] The projection exposure apparatus 100 according to the present embodiment includes a light source 2 serving as a light irradiation unit, a control unit 11 that controls each member in the projection exposure apparatus 100, a member that receives a drive command from the control unit 11 or notifies the control unit 11 of a measurement result, and a storage unit 30.

[0016] Note that the control unit 11 in the present embodiment is also a control unit of the position detection device 1, and is also a detection unit that detects the position of a position detection target. The members to which a drive command is notified from the control unit 11 are an ND filter 20, an illumination optical system 21, a reticle stage 23 (original plate stage), a substrate stage 24, and a projection optical system 25. The members that notify the control unit 11 of measurement results are a first illuminance detection unit 22, a second illuminance detection unit 26, a focus sensor 27, an alignment scope 28, and a light amount sensor (calibration sensor) 29. The storage unit 30 is, for example, a recording medium such as a hard disk, and stores a plurality of light amount distributions. However, the storage unit 30 is not limited to the example shown in FIG. 1, and may be, for example, a part of the control unit 11 or a host computer. The position detection device 1 includes, in the projection exposure apparatus 100, the control unit 11, the ND filter 20, the light amount sensor 29, and the storage unit 30.

[0017] The control unit 11 notifies a light emission command to the light source 2, and the light source 2 emits light (laser light) based on the notified light emission command. In the present embodiment, a plurality of ND filters 20 having different dimming rates are provided as main dimming means, and by switching the ND filters 20, the light incident on the light amount sensor 29 from the light source 2 is dimmed to an arbitrary light amount. However, there is no particular limitation on the dimming means as long as it can dim the light from the light source 2. The illumination optical system 21 can illuminate the reticle in a plurality of illumination modes using the light from the light source 2.

[0018] The first illuminance detection unit 22 measures the illuminance of the light that has passed through the illumination optical system 21, and notifies the control unit 11 of the measurement result. The reticle stage 23 holds a reticle (not shown) that is an original plate. The substrate stage 24 holds a substrate (not shown). The projection optical system 25 reduction-projects a circuit pattern formed on the reticle onto the substrate. The second illuminance detection unit 26 is disposed on the substrate stage 24, measures the illuminance of light with which the substrate is irradiated, and notifies the control unit 11 of the measurement result. The focus sensor 27 measures the focus (focal point) at an arbitrary position on the substrate stage 24, and notifies the control unit 11 of the measurement result. The alignment scope 28 measures an alignment mark on the substrate or the substrate stage 24, and notifies the control unit 11 of the measurement result.

[0019] A calibration mark CM (first mark) is provided on the reticle or reticle stage 23 (first member). The calibration mark CM has an aperture pattern. In addition, a reference mark RM (second mark) of an aperture pattern corresponding to the image (projected image) of the calibration mark CM provided on the reticle or reticle stage 23 is provided on the substrate (not shown) or substrate stage 24 (second member). In this embodiment, the calibration mark CM is provided on the reticle stage 23 and the reference mark RM is provided on the substrate stage 24.

[0020] The light intensity sensor 29 is positioned on the substrate stage 24 and receives light emitted from the light source 2, which passes through the calibration mark CM, the projection optical system 25, and the reference mark RM. The light intensity sensor 29 then detects the amount of light received and notifies the control unit 11. From the notified amount of light, the control unit 11 derives a light intensity distribution that shows the relationship between the detection position of the light intensity and the magnitude of the light intensity. In this embodiment, the light from the light source 2 passes through the calibration mark CM and the reference mark RM and is received by the light intensity sensor 29. However, the light intensity sensor 29 may be configured to receive light emitted from the light source 2 and reflected by the calibration mark CM and the reference mark RM.

[0021] Here, the method by which the projection exposure apparatus 100 in this embodiment performs exposure processing on a substrate will be described. Light from the light source 2 (exposure light) illuminates the reticle held on the reticle stage 23 via the illumination optical system 21. The light that has passed through the reticle is irradiated onto the substrate via the projection optical system 25. At this time, the pattern on the reticle is imaged onto the substrate surface. The projection exposure apparatus 100 exposes the shot area on the substrate in this manner and performs exposure similarly for each of the multiple shot areas.

[0022] Figure 2 is a schematic diagram illustrating how the light intensity sensor 29 in this embodiment detects light that has passed through the calibration mark CM and the reference mark RM. Light from the light source 2 passes through the aperture pattern of the calibration mark CM provided on the reticle stage 23 and is projected onto the substrate stage 24 as an image of the aperture pattern via the projection optical system 25. Light that has passed through the aperture pattern of the calibration mark CM and then through the aperture pattern of the reference mark RM via the projection optical system 25 reaches the light intensity sensor 29 provided on the substrate stage 24. The light intensity sensor 29 detects the amount of light it has received and notifies the control unit 11, which derives the light intensity distribution from the notified amount of light. In other words, the light intensity distribution derived based on the amount of light detected by the light intensity sensor 29 is the detection result of light that has passed through the calibration mark CM and the reference mark RM. Furthermore, the light intensity is greatest at the position where the image (projected image) of the aperture pattern of the calibration mark CM and the aperture pattern of the reference mark RM coincide.

[0023] Here, the method for deriving the light intensity distribution in this embodiment will be described. First, the reticle stage 23 is driven to move the calibration mark CM to a predetermined position (the position where the light emitted from the light source 2 passes through the aperture pattern of the calibration mark CM). The aperture pattern of the calibration mark CM, illuminated by the light source 2, is then imaged onto the substrate stage 24 by the projection optical system 25. Next, the substrate stage 24 is driven so that the aperture pattern of the reference mark RM overlaps with the image of the aperture pattern of the calibration mark CM. By moving the substrate stage 24, the position of the substrate stage 24 relative to the reticle stage 23 is changed, and the position of the reference mark RM relative to the calibration mark CM is changed. The light intensity distribution is derived by changing the position of the reference mark RM relative to the calibration mark CM in the positive and negative directions on a predetermined axis (for example, the X-axis or Y-axis) with respect to the detection start position.

[0024] Then, based on the light intensity distribution derived by the control unit 11, the relative positions of the reticle stage 23 and the substrate stage 24 are detected. Based on the position detection results, the control unit 11 performs alignment (calibration) of the reticle stage 23 and the substrate stage 24 so that the amount of light detected by the light intensity sensor 29 is maximized.

[0025] The light intensity distribution shown in Figure 3 is derived using the method described above. Figure 3 is an example of a light intensity distribution derived based on the light intensity detected by the light intensity sensor 29 in this embodiment. In the example in Figure 3, the detection start position is shifted from the peak position of the light intensity distribution, so the light intensity at the detection start position is less than the peak light intensity of the light intensity distribution. Therefore, the control unit 11 performs relative alignment (calibration) of the reticle stage 23 and the substrate stage 24 so that the light intensity detected by the light intensity sensor 29 is maximized.

[0026] As described above, in the projection exposure apparatus 100 of this embodiment, the control unit 11 controls the stage and other components to perform calibration based on the position of the target detected by the position detection device 1. The necessity of the calibration performed in this embodiment will now be explained. The projection optical system 25 generates aberrations due to heat from the light emitted from the light source 2, changes in atmospheric pressure, continuous operation of the apparatus, mechanical changes due to aging, etc. If exposure processing is performed while aberrations have occurred, the results of the exposure processing will deteriorate due to the effects of the aberrations. Therefore, the control unit 11 periodically uses the light intensity sensor 29 to align the reticle stage 23 and the substrate stage 24, taking into account the effects of the projection lens aberrations. This makes it possible to perform exposure processing at an appropriate position that takes into account the effects of the projection lens aberrations, and reduces the adverse effects of aberrations on the results of the exposure processing. Thus, in order to reduce the adverse effects of aberrations, it is desirable to perform calibration at regular intervals (after a certain cumulative usage time).

[0027] Figure 4 shows an example of the light intensity distribution when the amount of light received by the light intensity sensor 29 in this embodiment is greater than the light reception limit. When position detection is performed using the light intensity sensor 29, if the amount of light received by the light intensity sensor 29 is greater than the light reception limit, the amount of accumulated charge (voltage) at the pixels of the light intensity sensor 29 becomes saturated. In such a case, the light intensity sensor 29 outputs a constant value (light reception limit value) as shown in Figure 4, and the peak position cannot be derived. For this reason, it is desirable to reduce the amount of light received by the light intensity sensor 29 so that the peak position can be determined by making the amount of light below the light reception limit. However, when the amount of light received by the light intensity sensor 29 is greater than the light reception limit, the required amount of attenuation is unclear because the magnitude of the peak in the light intensity distribution is unknown. For this reason, generally, the attenuation rate is changed and the amount of light measured by the light intensity sensor 29 for the attenuated light is measured repeatedly, and the attenuation condition when the light intensity distribution consists of light below the light reception limit is set as the appropriate attenuation condition. This method of repeatedly performing dimming and measuring the amount of dimmed light using the light intensity sensor 29 takes time to derive appropriate dimming conditions.

[0028] Therefore, in this embodiment, the most similar light intensity distribution and the optimal light intensity distribution are selected from among the multiple light intensity distributions stored in the memory unit 30, and appropriate attenuation conditions are derived based on the selected light intensity distribution. Thus, according to this embodiment, even when a light intensity greater than the light reception limit of the light intensity sensor 29 is received, appropriate attenuation conditions can be derived in a short time.

[0029] Multiple light intensity distributions include a number of light intensity distribution groups obtained under multiple attenuation conditions for a given optical condition, equal to the number of optical conditions. For example, if there are 3 optical conditions and 10 attenuation conditions, there are 3 light intensity distribution groups, each containing 10 light intensity distributions obtained under 10 attenuation conditions for a given optical condition. Therefore, multiple light intensity distributions include a total of 30 light intensity distributions.

[0030] In this embodiment, the optical conditions include information regarding the illumination mode and the numerical aperture (NA) of the projection optical system on the imaging side. The illumination mode (pupil intensity distribution) can be, for example, conventional illumination, annular illumination (a modified illumination), quadrupole illumination, or dipole illumination. Note that the optical conditions are not limited to those assumed in this embodiment, but can be any elements that affect the amount of light. For example, σ, which is the value obtained by dividing the numerical aperture (NA) of the illumination optical system by the numerical aperture (NA) of the projection optical system on the illumination optical system side, may be added as a condition.

[0031] In this embodiment, the type of attenuation condition to be derived differs depending on whether the attenuation means is an ND filter 20 or reducing the amount of light emitted (reducing the voltage applied to the light source). When the attenuation means is an ND filter 20, the derivation of the attenuation condition involves selecting (deriving) an ND filter with an appropriate attenuation rate. When the attenuation means is reducing the amount of light emitted from the light source, the derivation of the attenuation condition involves deriving (determining) the reduction rate (or amount) of the amount of light emitted (voltage applied to the light source). However, it is also possible to configure the system to obtain an appropriate attenuation rate by combining these two attenuation means. When using both attenuation means, it is desirable to adjust the difference between the attenuation rate of the ND filter 20 and the appropriate attenuation condition (appropriate attenuation rate) by continuously adjusting the amount of light emitted from the light source, as the attenuation rate of the ND filter 20 is discrete.

[0032] Figure 5 shows an example of deriving the light intensity distribution for multiple attenuation conditions under one optical condition in this embodiment. The ND filter 20 with the smallest attenuation rate (highest transmittance) is ND1. On the other hand, the ND filter 20 with the highest attenuation rate (lowest transmittance) is ND10. In the example in Figure 5, there are eight ND filters 20 with different attenuation rates between ND1 and ND10, and a total of 10 ND filters 20 are used as attenuation means. With attenuation rates of ND1 to ND6, the attenuation is insufficient, and the light intensity sensor 29 receives a light intensity greater than its detection limit, so the size and position of the peak in the light intensity distribution are unclear. With attenuation rates of ND7 to ND10, the attenuation is sufficient, so the light intensity sensor 29 receives a light intensity below its detection limit, and the size and position of the peak in the light intensity distribution are clear.

[0033] Here, we will explain the optimal light intensity distribution. The optimal light intensity distribution is one in which the peak position can be accurately detected. Specifically, it is a light intensity distribution in which the light intensity sensor 29 does not receive a light intensity greater than its light reception limit, and the slope near the peak is steep. In other words, in the example of Figure 5, the light intensity distribution derived when the light is attenuated by the ND7 filter can be said to be the optimal light intensity distribution. Furthermore, although this embodiment describes an example having 10 ND filters 20 with different attenuation rates, the number of steps for switching the attenuation rate of the ND filter 20 is not particularly limited.

[0034] Figure 6 is a flowchart for storing multiple light intensity distributions in this embodiment. The control unit 11 determines whether or not a light intensity distribution has been derived for all attenuation conditions for all optical conditions (S101). Here, the user sets the optical conditions so that all optical conditions include all illumination modes that can be assumed by the projection exposure apparatus 100. If a light intensity distribution has been derived for all attenuation conditions for all optical conditions, the process ends. If a light intensity distribution has not been derived for all attenuation conditions for all optical conditions, the process switches to an optical condition for which a light intensity distribution has not been derived (S102).

[0035] Next, the ND filter 20, which is the light-reducing means, is switched to the filter with the smallest light-reducing rate (S103). Then, the control unit 11 derives a light intensity distribution based on the amount of light received by the light intensity sensor 29, and the storage unit 30 stores the derived light intensity distribution (S104). The control unit 11 determines whether or not a light intensity distribution has been derived for all ND filters 20 under the current optical conditions (S105). If a light intensity distribution has been derived for all ND filters 20, the process returns to step S101. If a light intensity distribution has not been derived for all ND filters 20, the ND filter 20 is switched to a filter with a light-reducing rate one step higher (S106), and the process returns to step S104. By executing this flowchart, a light intensity distribution can be derived for all light-reducing conditions under all optical conditions, and the storage unit 30 can store multiple light intensity distributions. Furthermore, the memory unit 30 stores not only the multiple light intensity distributions stored in the flowchart of Figure 6, but also the optical conditions and attenuation conditions at the time of light intensity detection, which are associated with each of the multiple light intensity distributions. It is also desirable to periodically update the multiple light intensity distributions.

[0036] In this embodiment, the multiple light intensity distributions stored must include both a light intensity distribution where the peak light intensity is greater than the light-receiving limit and a light intensity distribution where the peak light intensity is less than or equal to the light-receiving limit, i.e., a light intensity distribution that does not include any light intensity greater than the light-receiving limit. This is because, when a light intensity greater than the light-receiving limit is detected, the most similar light intensity distribution (a light intensity distribution where the peak light intensity is greater than the light-receiving limit) and the optimal light intensity distribution (a light intensity distribution where the peak light intensity is less than or equal to the light-receiving limit) among the multiple light intensity distributions are used to derive appropriate attenuation conditions. The optical conditions and attenuation conditions for storing the multiple light intensity distributions are specified in advance by the user.

[0037] In the flowchart in Figure 6, when storing multiple light intensity distributions, all ND filters are applied to one optical condition and the light intensity distribution is derived for each. However, once a suitable light intensity distribution is obtained, it is possible to switch to another optical condition or terminate the detection of light intensity distributions. Doing so can reduce the time required to store multiple light intensity distributions.

[0038] Figure 7 is a flowchart for deriving appropriate attenuation conditions in this embodiment. First, the control unit 11 checks the optical conditions A1 at the time of light intensity detection of the light intensity distribution A (acquired light intensity distribution) when a light intensity greater than the newly acquired light reception limit is received (S201).

[0039] The control unit 11 determines whether or not there is a light intensity distribution among the stored multiple light intensity distributions that was obtained by detection under the same optical conditions as optical condition A1 (S202). If there is no light intensity distribution obtained by detection under the same optical conditions as optical condition A1, the control unit 11 first selects a light intensity distribution from the stored multiple light intensity distributions that was obtained by detection under the same illumination mode as optical condition A1. Then, from among that light intensity distribution, it selects an optical condition for a light intensity distribution obtained by detection under optical conditions where the optical conditions other than the illumination mode are similar to those of optical condition A1 (S203). Note that multiple optical conditions can be selected in step S203.

[0040] If a light intensity distribution is obtained by detection under the same optical conditions as optical condition A1, the same optical conditions as optical condition A1 are selected (S204). Next, the control unit 11 selects from the light intensity distributions detected by the light illuminated by the selected optical conditions (first optical conditions) the light intensity distribution B (second light intensity distribution) that is most similar to light intensity distribution A and the optimal light intensity distribution C (first light intensity distribution) (S205).

[0041] Here, the most similar light intensity distribution B is a light intensity distribution that is similar to light intensity distribution A in terms of the slope of the distribution and the length of the interval in which a light intensity greater than the light reception limit is detected. Light intensity distribution A is a light intensity distribution when a light intensity greater than the light reception limit is received, and it is a light intensity distribution with an unclear peak position. Therefore, the most similar light intensity distribution B is also a light intensity distribution when a light intensity greater than the light reception limit is received, and it is a light intensity distribution with an unclear peak position. The optimal light intensity distribution C is, as described above, a light intensity distribution in which the light intensity sensor 29 does not receive a light intensity greater than the light reception limit, the light intensity at the peak position is below the light reception limit and the peak position is detectable, and preferably has a steep slope near the peak. The control unit 11 then stores the dimming condition CL (first dimming condition) for the optimal light intensity distribution C (S206). Note that light intensity distribution B is a light intensity distribution that has been attenuated under a second attenuation condition different from the attenuation condition CL (first attenuation condition), or that has not been attenuated by any attenuation means.

[0042] Next, it is determined whether or not to consider the changes over time in the projection exposure apparatus 100 (S207). This determination may be made, for example, by the control unit 11 considering the changes over time if a time equal to or greater than a preset threshold for time has elapsed, and not considering the changes over time if it is less than the threshold. Alternatively, the cumulative operating time, cumulative downtime, number of starts, number of substrates processed, etc., of the projection exposure apparatus 100 may be considered to determine whether or not to consider the effects of changes over time since the multiple light intensity distributions were stored. Alternatively, the user may determine whether or not to consider changes over time and input this through the input unit (not shown). When the effect of changes over time is small, it is better not to consider changes over time, and when the effect of changes over time is large, it is better to consider changes over time. Here, changes over time in the projection exposure apparatus 100 refer to changes in the parameters of elements that affect the light intensity, which causes the amount of light received by the light intensity sensor 29 to change even under the same conditions. As a result, even if the dimming condition CL stored in step S206 is used, an appropriate light intensity distribution may not be obtained due to the effects of changes over time. Factors that affect the amount of light include, for example, fluctuations in the output of light source 2, fluctuations in the transmittance of projection optical system 25, and fluctuations in the light attenuation rate (transmittance) of ND filter 20. For example, the lenses of projection optical system 25 and ND filter 20 have a property of becoming cloudy over time when they are not exposed to light, and as the surface becomes cloudy, the amount of light passing through the lenses of projection optical system 25 and ND filter 20 is reduced compared to before the clouding occurred.

[0043] If it is determined in step S207 that the change over time should not be considered, the control unit 11 stores the dimming condition CL stored in step S206 as the appropriate dimming condition NL (S208) and terminates.

[0044] If it is determined in step S207 that changes over time should be considered, the control unit 11 derives a correction rate (ratio) of the light intensity value at a predetermined position in light intensity distribution B to the light intensity value at a predetermined position in light intensity distribution A (S209). The method and meaning of deriving this correction rate will be described later. Then, using the attenuation condition CL obtained from the optimal light intensity distribution C and the correction rate of the light intensity value derived in step S209, an appropriate attenuation condition NL is derived (S210), and the process ends. By performing steps S209 and S210, it is possible to derive an appropriate attenuation condition NL by considering the changes in the parameters of the elements that affect the light intensity over time. In this embodiment, the correction rate of the light intensity value at a predetermined position in the light intensity distribution is used to capture the amount of change of the elements that affect the light intensity, but other methods may be used as long as the amount of change of the elements that affect the light intensity is known.

[0045] The control unit 11 then reduces the amount of light incident on the light intensity sensor 29 via the two marks using a dimming means corresponding to the appropriate dimming condition NL described above, thereby enabling light intensity detection at a light intensity below the light reception limit. Since the results of light intensity detection at a light intensity below the light reception limit can be used in this way, the accuracy of relative position detection between the reticle or reticle stage 23 and the substrate or substrate stage 24 can be improved.

[0046] Here, we will explain how to derive the correction rate (ratio) of the light intensity value at a predetermined position in light intensity distribution B to the light intensity value at a predetermined position in light intensity distribution A in step S209. If the attenuation conditions when detecting light intensity are the same for light intensity distribution A and light intensity distribution B, we derive the correction rate dR of the light intensity value, which represents the rate of change in light intensity over time. If the attenuation conditions when detecting light intensity are different for light intensity distribution A and light intensity distribution B, we derive the correction rate dG of the light intensity value, which encompasses two elements: the rate of change in light intensity over time and the difference in light intensity due to the difference in attenuation conditions.

[0047] Figure 8 shows an example of deriving the correction rate dR of the light intensity value, which indicates the rate of change in light intensity over time, in this embodiment. Even if the attenuation conditions for light intensity distribution A and light intensity distribution B are the same, the light intensity values ​​may differ due to the effects of time. In this case, using the light intensity value P of light intensity distribution A at a predetermined position as a reference, the correction rate dR of the light intensity value Q of light intensity distribution B at a predetermined position relative to the light intensity value P is derived using equation (1). dR = Q ÷ P ···(1)

[0048] Here, the predetermined position is defined as a position located at a predetermined distance from the center of the section in the light intensity distribution A where the light intensity is above the light-receiving limit. This predetermined distance can be freely set by the user to match the characteristics of the light intensity distribution. However, in order to reduce the error included in the light intensity correction rate dR, it is preferable that the light intensity value at the predetermined position is 50% or more of the light intensity value at the light-receiving limit.

[0049] Furthermore, if the attenuation conditions during light intensity detection differ between light intensity distribution A and light intensity distribution B, it is not possible to derive an appropriate attenuation condition NL using the correction rate dR of the light intensity value, which indicates the rate of change in light intensity over time. Therefore, an appropriate attenuation condition NL is derived using a correction rate dG of the light intensity value that encompasses two elements: the rate of change in light intensity over time and the difference in light intensity due to the difference in attenuation conditions. Figure 9 shows an example of deriving the correction rate dG of the light intensity value that encompasses two elements: the rate of change in light intensity over time and the difference in light intensity due to the difference in attenuation conditions, in this embodiment. First, in order to find the correction rate dG of the light intensity value, light intensity distribution A is adjusted to light intensity distribution A' that matches the attenuation conditions of light intensity distribution B. For example, the attenuation condition during light intensity detection for light intensity distribution A is ND4, and the attenuation rate of the ND4 filter is set to 0.3 (30%). Also, the attenuation amount during light intensity detection for light intensity distribution B is ND5, and the attenuation rate of the ND5 filter is set to 0.4 (40%). The ND4 attenuation condition for light distribution A is 10% lower than the ND5 attenuation condition for light distribution B. Therefore, light distribution A is adjusted by 10% to match the attenuation rate of light distribution B, and this is designated as light distribution A'.

[0050] Then, the correction factor dG for the light intensity value Q of the light intensity distribution B at a predetermined position relative to the light intensity value P' of the light intensity distribution A' at a predetermined position is derived using equation (2). dG = Q ÷ P' ···(2)

[0051] Here, the predetermined position is set at a predetermined distance from the center of the section in the light intensity distribution A' where the light intensity is above the light-receiving limit, similar to when the light intensity correction rate dR was derived. This predetermined distance can be freely set by the user to match the characteristics of the light intensity distribution. However, in order to reduce the error included in the light intensity correction rate dG, it is preferable that the light intensity value at the predetermined position is 50% or more of the light intensity value at the light-receiving limit. Note that the predetermined position is not limited to the position described in this embodiment, as long as the light intensity correction rate can be determined.

[0052] The derivation of the appropriate attenuation condition NL for step S210 is explained below. When the attenuation conditions during light intensity detection are the same for light intensity distribution A and light intensity distribution B, the following equation (3) is applied using the light intensity value correction factor dR. When the attenuation conditions during light intensity detection are different for light intensity distribution A and light intensity distribution B, the following equation (4) is applied using the light intensity value correction factor dG. NL = CL ÷ dR ···(3) NL = CL ÷ dG ···(4)

[0053] For example, if the attenuation condition CL = 0.4 (40%) for the optimal light intensity distribution C and the correction rate dR or dG = 0.9 for the light intensity value, applying equation (3) or equation (4) can be derived to find that the appropriate attenuation condition NL is approximately 44.4%.

[0054] According to this embodiment, even if the light received by the light intensity sensor 29 is greater than the light reception limit, multiple light intensity distributions associated with each condition are stored in advance, and an appropriate attenuation condition NL is derived using the stored multiple light intensity distributions, so an appropriate attenuation condition NL can be derived in a short time. Furthermore, this embodiment is particularly effective when the light received by the light intensity sensor 29 is greater than the light reception limit, so this embodiment may be applied only when the light received by the light intensity sensor 29 is greater than the light reception limit. In this case, when the light received by the light intensity sensor 29 is less than or equal to the light reception limit, that is, when the peak position of the light intensity distribution is clear, an appropriate attenuation condition NL is derived using a method different from that of this embodiment.

[0055] <Second Embodiment> This embodiment is characterized by manufacturing an article using the position detection device described in the first embodiment.

[0056] Figure 10 is a flowchart of the method for manufacturing an article in this embodiment. A position detection step (S510) is performed to detect the relative position of the reticle or reticle stage 23 and the substrate or substrate stage 24 using the position detection device described in the first embodiment. Then, an alignment step (S520) is performed to align (calibrate) the relative position of the reticle or reticle stage 23 and the substrate or substrate stage 24 based on the detection result of the position detection step. After that, a forming step (S530) is performed to form a pattern on the substrate, and a manufacturing step (S540) is performed to manufacture an article from the substrate on which the pattern has been formed in the forming step.

[0057] The products manufactured using this method include, for example, semiconductor IC elements, liquid crystal display elements, color filters, MEMS, and the like.

[0058] The formation process involves, for example, exposing a substrate (such as a silicon wafer or glass plate) coated with a photosensitive material onto a pattern material using an exposure device (lithography device) to form a pattern on the substrate.

[0059] The manufacturing process includes, for example, developing a patterned substrate (photosensitive material), etching and resist removal from the developed substrate, dicing, bonding, and packaging. This manufacturing method allows for the production of higher-quality articles than conventional methods.

Claims

1. A light intensity sensor that receives light through a first mark provided on a first member and a second mark provided on a second member, The light intensity sensor receives light with a light intensity greater than its light reception limit, and the detection unit uses the result of the light intensity sensor receiving attenuated light based on attenuation conditions derived from the acquired light intensity distribution, which is the light intensity distribution of the light received by the light intensity sensor, and a plurality of light intensity distributions stored in the memory unit, to detect the relative position of the first member and the second member. The plurality of light intensity distributions include a light intensity distribution that does not include a light intensity greater than the light-receiving limit, The derived attenuation conditions are derived based on attenuation conditions corresponding to a light intensity distribution that does not include light intensity greater than the light-receiving limit, which corresponds to the optical conditions when the acquired light intensity distribution was obtained. A position detection device characterized by the following features.

2. The position detection device according to claim 1, characterized in that the plurality of light intensity distributions include a light intensity distribution that includes a light intensity greater than the light reception limit of the light intensity sensor and a light intensity distribution that does not include a light intensity greater than the light reception limit.

3. The position detection device according to claim 2, characterized in that the first light intensity distribution, which is one of the light intensity distributions when light with an intensity below the light reception limit is received, is the result of receiving light that is illuminated by a first optical condition and attenuated by a first attenuation condition, and the second light intensity distribution, which is one of the light intensity distributions when light with an intensity greater than the light reception limit is received, is the result of receiving light that is illuminated by the first optical condition and attenuated by a second attenuation condition different from the first attenuation condition, or not attenuated at all.

4. The position detection device according to claim 3, characterized in that the deriveted dimming condition is derived using the first dimming condition.

5. The position detection device according to claim 2, characterized in that the derived dimming condition is derived using a correction rate for correcting the effect of changes in the amount of light received by the light intensity sensor over time.

6. The position detection device according to claim 5, characterized in that the correction rate is derived using the ratio of the amount of light received at a predetermined position in a light intensity distribution that is highly similar to the acquired light intensity distribution among the plurality of light intensity distributions to the amount of light received at a predetermined position that is a predetermined distance away from the center of the section in the acquired light intensity distribution in which the light intensity sensor receives an amount of light exceeding the light receiving limit.

7. The position detection device according to claim 3, characterized in that when the attenuation condition for the light used to derive the acquired light intensity distribution is different from the second attenuation condition, the acquired light intensity distribution is adjusted based on the difference in the attenuation conditions.

8. The position detection device according to claim 1, characterized in that the storage unit is part of the control unit that controls the position detection device or a host computer.

9. The position detection device according to claim 4, characterized in that the plurality of optical conditions, including the first optical condition, include information regarding the pupil plane intensity distribution of an illumination optical system that illuminates a patterned original plate.

10. An acquisition step to acquire the acquired light intensity distribution, which is the result of a light intensity sensor receiving light through a first mark provided on a first member and a second mark provided on a second member. When the light intensity sensor receives light with an intensity greater than its light reception limit, a derivation step is performed to derive a light reduction condition for reducing the light based on a plurality of stored light intensity distributions and the acquired light intensity distribution. The process includes a position detection step in which the relative positions of the first member and the second member are detected using the result of the light intensity sensor receiving light that has been dimmed based on the dimming conditions derived in the derivation step, The plurality of light intensity distributions include a light intensity distribution that does not include a light intensity greater than the light-receiving limit, In the derivation step, the attenuation conditions are derived based on the attenuation conditions corresponding to a light intensity distribution that does not include light intensity greater than the light-receiving limit, which corresponds to the optical conditions when the acquired light intensity distribution was acquired. A method for detecting a position characterized by the features described herein.

11. A lithography apparatus for forming patterns on a substrate, A master plate stage that holds a master plate on which the aforementioned pattern has been formed, A substrate stage for holding the aforementioned substrate, A light intensity sensor that receives light transmitted through a first mark provided on the original plate or the original plate stage and a second mark provided on the substrate or the substrate stage, The system includes a detection unit that, when the light intensity sensor receives light with a light intensity greater than its light reception limit, uses the result of the light intensity sensor receiving attenuated light based on attenuation conditions derived from the acquired light intensity distribution, which is the light intensity distribution of the light received by the light intensity sensor, and a plurality of light intensity distributions stored in the memory unit, to detect the relative position between the original plate or the original plate stage and the substrate or the substrate stage. The plurality of light intensity distributions include a light intensity distribution that does not include a light intensity greater than the light-receiving limit, The derived attenuation conditions are derived based on attenuation conditions corresponding to a light intensity distribution that does not include light intensity greater than the light-receiving limit, which corresponds to the optical conditions when the acquired light intensity distribution was obtained. A lithography apparatus characterized by the following features.

12. The system includes a dimming means for dimming the light incident on the light intensity sensor based on the dimming conditions, The lithography apparatus according to claim 11, characterized in that the light-reducing means has a plurality of ND filters with different light-reducing rates for reducing light.

13. The lithography apparatus according to claim 11, characterized in that the amount of light incident on the light intensity sensor is reduced by adjusting the amount of light emitted from a light source.

14. A position detection step of performing relative position detection between a reticle or reticle stage and a substrate or substrate stage using a position detection device according to any one of claims 1 to 9, A positioning step is performed to align the relative position of the reticle or the reticle stage with the substrate or the substrate stage based on the detection result of the position detection step, After the alignment step, a forming step is performed to form a pattern on the substrate, A manufacturing process for manufacturing an article from the substrate on which the pattern has been formed in the forming step, A method for manufacturing an article, characterized by having the following:

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