JP2025075644A - MEASURING APPARATUS, MEASURING APPARATUS CONTROL METHOD, SUBSTRATE PROCESSING APPARATUS, AND ARTICLE MANUFACTURING METHOD - Google Patents

Abstract

To provide a measuring device advantageous for suppressing a decrease in throughput while having a simple configuration.SOLUTION: A measuring device, which detects second light from a pattern illuminated with first light emitted from a light source to measure a position of the pattern, includes: a wavelength control portion that controls a wavelength of the first light by changing an incident position of the first light with respect to a wavelength variable element; a light quantity adjustment portion that adjusts a light quantity of the first light whose wavelength is controlled by the wavelength control portion; and a control portion that controls the light quantity adjustment portion when the wavelength control portion switches a wavelength band of the first light from a first wavelength band to a second wavelength band on the basis of first spectral intensity which is spectral intensity in the first wavelength band of the first light and second spectral intensity which is spectral intensity in the second wavelength band of the first light.SELECTED DRAWING: Figure 2

Description

The present invention relates to a measurement device, a control method for the measurement device, a substrate processing device, and an article manufacturing method.

In the manufacture of products such as semiconductor devices, MEMS, color filters, and flat panel displays, patterns formed on substrates are becoming finer, and there is an increasing demand for improved dimensional accuracy of the patterns. For this reason, substrate processing equipment such as exposure devices requires high accuracy in measuring the position of the substrate on which the pattern is formed.

An exposure apparatus forms a pattern on a substrate by focusing the exposure light at a predetermined position on the substrate via a projection optical system and then moving the stage on which the substrate is placed. In an exposure apparatus, the accuracy of measuring the pattern on the substrate in order to align the relative position between the exposure light and the predetermined position on the substrate where the pattern is formed, as well as the accuracy of measuring the relative positions between patterns formed on different layers on the substrate, are important.

One method for measuring the position of a pattern formed on a substrate is to illuminate the pattern and detect the light reflected by the pattern. In order to improve the measurement accuracy of the pattern, it is possible to select the wavelength of the light that illuminates the pattern depending on the physical and optical characteristics of the pattern and its surrounding area. The physical properties of the material that constitutes the pattern and the shape of the pattern may differ depending on the process in which the substrate is processed. Therefore, by illuminating the pattern with light of a wavelength selected depending on the process in which the substrate is processed, the strength of the detection signal of the light reflected from the pattern is improved, thereby reducing errors in the detection signal and improving the accuracy of the position measurement of the pattern.

Patent Document 1 discloses that in a measurement device for measuring a pattern on a substrate, when the wavelength of light illuminating the pattern is made broadband, a decrease in throughput is suppressed by accurately adjusting the amount of detection light using a neutral density filter. Patent Document 2 discloses that in a measurement device for measuring a pattern on a substrate, a so-called variable wavelength filter is configured in which the wavelength of light that illuminates the pattern by passing through the filter is changed by driving the filter. Patent Document 2 further discloses that two filters are configured and light is illuminated by selecting an arbitrary center wavelength and wavelength width.

Patent No. 7075278 Patent No. 7238041

In Patent Document 1, a relationship (dimming table) of the transmittance for each wavelength band for each of a plurality of neutral density filters is obtained, and a neutral density filter is selected based on the relationship. In this case, the wavelength band is limited, which is disadvantageous in terms of process robustness. In Patent Document 2, a variable wavelength filter is used, but since the combinations of center wavelength and wavelength width by the variable wavelength filter are substantially infinite, it is difficult to prepare a dimming table for each wavelength as in Patent Document 1. Therefore, in the conventional technology, when selecting an arbitrary wavelength band (center wavelength, wavelength width) using a variable wavelength filter, the number of wavelength bands cannot be limited, so the relationship between the wavelength band and the transmittance of the neutral density filter region cannot be constructed. In this case, it takes time to adjust the amount of light of the detection light using the neutral density filter, which results in a decrease in throughput.

The present invention provides, for example, a measurement device that has a simple configuration yet is advantageous in suppressing a decrease in throughput.

According to one aspect of the present invention, there is provided a measurement device that measures the position of a pattern by detecting second light from a pattern illuminated by first light emitted from a light source, the measurement device comprising: a wavelength control unit that controls the wavelength of the first light by changing the incident position of the first light with respect to a wavelength tunable element; a light amount adjustment unit that adjusts the amount of the first light whose wavelength has been controlled by the wavelength control unit; and a control unit that controls the light amount adjustment unit when switching the wavelength band of the first light from the first wavelength band to the second wavelength band by the wavelength control unit based on a first spectral intensity, which is the spectral intensity in a first wavelength band of the first light, and a second spectral intensity, which is the spectral intensity in a second wavelength band of the first light.

The present invention can provide, for example, a measurement device that has a simple configuration yet is advantageous in suppressing a decrease in throughput.

FIG. 1 is a diagram showing the configuration of a measurement apparatus. FIG. 2 is a diagram showing the configuration of a measurement unit. FIG. 2 is a diagram showing the configuration of an illumination unit. 5 is a diagram showing the relationship between the wavelength and intensity of light transmitted through a wavelength tunable portion. FIG. 4 is a diagram showing the configuration of a light amount adjustment unit. 4 is a flowchart of a dimming operation. 5A to 5C are diagrams illustrating examples of wavelength characteristic information, neutral density filter transmittance, and detected light amount for each wavelength band. FIG. 4 is a diagram for explaining wavelength characteristic information. FIG. 1 is a diagram showing the configuration of an exposure apparatus. 4 is a flowchart of an exposure process.

The following embodiments are described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicate explanations are omitted.

First Embodiment
FIG. 1 is a diagram showing the configuration of a measurement apparatus 100 according to the first embodiment. In this specification and the drawings, directions are shown in an XYZ coordinate system with a horizontal plane as the XY plane. In general, a substrate 73, which is an object to be measured, is placed on a substrate stage WS so that its surface is parallel to the horizontal plane (XY plane). Therefore, in the following, directions perpendicular to each other in a plane along the surface of the substrate 73 are referred to as the X-axis and Y-axis, and a direction perpendicular to the X-axis and Y-axis is referred to as the Z-axis. In the following, directions parallel to the X-axis, Y-axis, and Z-axis in the XYZ coordinate system are referred to as the X-direction, Y-direction, and Z-direction, respectively, and the rotation direction around the X-axis, the rotation direction around the Y-axis, and the rotation direction around the Z-axis are referred to as the θX direction, the θY direction, and the θZ direction, respectively.

The measuring device 100 is a measuring device that measures the position of a pattern by detecting a second light from the pattern illuminated by a first light emitted from a light source. The measuring device 100 is configured to measure, for example, the positions in the X and Y directions of a pattern provided on the substrate 73. The measuring device 100 may be configured to measure, for example, the positions in the X and Y directions of patterns provided on different layers on the substrate 73, and to measure the distance between the respective patterns.

The measuring apparatus 100 may have a substrate stage WS that holds a substrate 73, a measuring unit 50, and a control unit 1100. The substrate 73 is an object for which alignment errors and overlay errors are measured by the measuring apparatus 100. The substrate 73 may be, for example, a substrate used to manufacture devices such as semiconductor elements and liquid crystal display elements. Specifically, the substrate 73 may be a wafer, a liquid crystal substrate, or another substrate to be processed.

The substrate stage WS holds the substrate 73 via a substrate chuck (not shown) and is configured to be driven by a stage drive unit (not shown). The stage drive unit includes a linear motor and the like, and can move the substrate 73 held by the substrate stage WS by driving the substrate stage WS in the X direction, Y direction, Z direction, θX direction, θY direction, and θZ direction. A mirror 82 is also arranged on the substrate stage WS. A laser interferometer 81 is also arranged at a position facing the mirror 82. The laser interferometer 81 measures the position of the substrate stage WS in the X direction by measuring the distance to the mirror 82 in the X direction. Similarly, laser interferometers (not shown) for measuring the positions of the substrate stage WS in the Y direction and the Z direction may also be arranged. The position of the substrate stage WS is measured in real time by these laser interferometers, and the measurement results are output to the control unit 1100. As a result, the substrate stage WS is driven to a predetermined position under the control of the control unit 1100. The measurement apparatus 100 may have a scale disposed on the substrate stage WS and an encoder that measures the position of the substrate stage WS by detecting the position of the scale.

The control unit 1100 controls each part of the measuring device 100 in an integrated manner to operate the measuring device 100. The control unit 1100 also executes measurement processing in the measuring device 100 and calculation processing of measurement values obtained by the measuring device 100. The control unit 1100 is composed of a computer (information processing device). The control unit 1100 has a processing unit having a processor such as a CPU that performs calculations for control according to a program, a ROM that stores control programs and fixed data, a work area of the processing unit, and a storage unit such as a RAM that stores temporary data. The control unit 1100 may also have a magnetic storage device (HDD) that can store a larger amount of data than ROM and RAM as a storage unit. The control unit 1100 may also have a drive device that loads external media such as CDs, DVDs, and memory cards to read and write data as a storage unit. In this embodiment, at least one of the ROM, RAM, magnetic storage device, and drive device is used as a storage unit, and the storage unit stores the control program, fixed data, work area of the processing unit, and temporary data.

The measurement unit 50 illuminates the pattern provided on the substrate 73, detects the light from the pattern, and captures the pattern provided on the substrate 73. FIG. 2 is a diagram showing the configuration of the measurement unit 50. The measurement unit 50 has an illumination system that illuminates the substrate 73 using light from the illumination unit 301, and an imaging system (detection system) that focuses the light from the pattern 72 on the detection unit 75 (forming an image of the pattern 72). The detection unit 75 has a light receiving unit (not shown) that receives the light from the pattern 72, and obtains a detection signal of the light received by the light receiving unit. The detection unit 75 can also function as an imaging unit that forms an imaging area for capturing an image of the pattern 72 by the light receiving unit. Here, the pattern 72 is a pattern for measuring alignment errors and overlay errors on the substrate 73, and the position of the pattern 72 is measured based on the detection signal obtained by the detection unit 75.

FIG. 3 is a diagram showing the configuration of the illumination unit 301. The illumination unit 301 can function as a wavelength control unit that controls the wavelength of the first light emitted from the light source. The illumination unit 301 as a wavelength control unit can include a light source 361, an illumination optical system 362, a wavelength variable unit 340 (variable wavelength filter), and a wavelength driving unit 341. The light (first light) emitted from the light source 361 is guided to the wavelength variable unit 340 via the illumination optical system 362. For the light source 361, a light source such as a laser light source, an LED, or a halogen lamp can be used. The illumination optical system 362 irradiates the light emitted from the light source 361 to the wavelength variable unit 340. The illumination optical system 362 can be, for example, an axially symmetric transmission optical system including a lens through which light passes. In addition, the illumination optical system 362 may include, for example, a reflection optical system including a mirror such as a concave mirror or a convex mirror, a cylindrical optical system including a cylindrical lens, or the like.

The wavelength variable unit 340 may be a wavelength variable element that changes the relationship between the wavelength and intensity of the irradiated light (hereinafter referred to as the "spectrum") depending on the position and angle at which the light is incident. The wavelength control unit is configured to continuously change the wavelength band of the first light by changing the position at which the first light is incident on the wavelength variable element. The spectrum may include, for example, information indicating the relationship between the wavelength and intensity of the light. The spectrum may also include, for example, information on the wavelength of the light at which the intensity of the light is maximum, minimum, or a predetermined value. The spectrum may also include, for example, information on the wavelength band of the light at which the intensity of the light is a value within a predetermined range. The spectrum may also include, for example, information on the waveform of the spectrum. The wavelength variable element is described as being a transmissive wavelength variable element, but may also be a reflective wavelength variable element.

The wavelength variable unit 340 is disposed at the light collecting position of the illumination optical system 362 on the optical axis of the illumination optical system 362, and is driven (moved) by the wavelength driving unit 341 (moving unit) in a direction perpendicular to the direction along the optical axis of the illumination optical system 362 (optical axis direction) (X direction in the example of FIG. 3). In this embodiment, the wavelength variable unit 340 is described as being driven in the X direction by the wavelength driving unit 341, but the direction of the driving axis (driving direction) of the wavelength driving unit 341 is not limited to the X direction. Note that, if the luminous flux diameter of the light incident on the wavelength variable unit 340 varies depending on the direction, it is desirable to drive the wavelength variable unit 340 in the direction in which the luminous flux diameter of the light is the shortest from the viewpoint of wavelength characteristics. Also, for example, if a cylindrical optical system is used in the illumination optical system 362, it is desirable to drive the wavelength variable unit 340 in the power direction of the cylindrical optical system.

The wavelength driver 341 has an actuator such as a linear motor, and can drive the actuator to move the wavelength variable unit 340 in a predetermined direction perpendicular to the optical axis. The position of the wavelength variable unit 340 is measured, for example, by an encoder or an interferometer, and the control unit 1100 controls the wavelength driver 341 so that the variable unit 340 is positioned at the target position based on the difference (control deviation) between the target position and the measured position.

The control unit 1100, which controls the illumination unit 301, positions the wavelength variable unit 340 using the wavelength drive unit 341 based on the relationship between the position of the wavelength variable unit 340 in a predetermined direction perpendicular to the optical axis and the wavelength of light passing through the wavelength variable unit 340. This allows the substrate 73 to be illuminated with light of the desired wavelength. Here, the predetermined direction perpendicular to the optical axis is a direction perpendicular to the optical axis of the illumination optical system 362, for example, the X direction or Y direction.

In this way, by changing the position of the wavelength variable section 340 by the wavelength driving section 341, the wavelength of the light passing through the wavelength variable section 340 can be changed. For example, a wavelength variable filter can be used as the wavelength variable section 340. Here, the wavelength variable filter is, for example, a bandpass filter having a multilayer laminated film formed on the surface on which the light is incident, and the film thickness of the multilayer laminated film is formed to be thick along the wavelength change direction. This causes the wavelength of the transmitted light to change continuously due to the interference of light. In addition, for example, a transmission type diffraction grating that separates light of different wavelengths using a diffraction grating formed in a light-transmitting member can also be used as the wavelength variable section 340.

Here, the wavelength variable unit 340 may include a full-pass region that passes the transmitted light without changing its wavelength. The illumination unit 301 drives the position of the wavelength variable unit 340 to the full-pass region using the wavelength driving unit 341, thereby emitting the light irradiated from the light source 361 without changing the wavelength band.

Now, referring again to FIG. 2, the light emitted from the illumination unit 301 enters the illumination aperture stop 64 via the illumination optical system 63. At the illumination aperture stop 64, the light beam diameter becomes smaller than that at the illumination unit 301. The light passing through the illumination aperture stop 64 enters the beam splitter 68 via the relay lens 67. The beam splitter 68 is, for example, a polarizing beam splitter, which transmits P-polarized light parallel to the Y direction and reflects S-polarized light parallel to the X direction. The light transmitted through the beam splitter 68 passes through the aperture stop 69, passes through the λ/4 plate 70, and is converted into circularly polarized light, and passes through the objective optical system 71 to Kohler illuminate the pattern 72 provided on the substrate 73.

The illumination optical system 63 has a light amount adjustment unit 36 that adjusts the amount of light of the first light that has passed through the wavelength variable unit 340. The light amount adjustment unit 36 is configured to be able to switch between a plurality of light-reducing filters having different transmittances for the light from the illumination unit 301. FIG. 5 shows an example of the configuration of the light amount adjustment unit 36. The control unit 1100 can adjust the intensity of the light that illuminates the substrate 73 with high precision by controlling the light amount adjustment unit 36. As a specific configuration, the illumination optical system 63 is provided with a light-reducing drive unit that drives the light amount adjustment unit 36 so as to selectively place one of the plurality of light-reducing filters provided in the light amount adjustment unit 36 on the optical path. The light-reducing drive unit is, for example, composed of a rotation mechanism that rotates a turret on which a plurality of light-reducing filters are provided. The control unit 1100 then controls the light-reducing drive unit to place one of the plurality of light-reducing filters on the optical path. The light amount adjustment unit 36 may have a configuration that allows a new neutral density filter to be added in addition to the multiple neutral density filters provided in advance.

As shown in FIG. 5, the light amount adjustment unit 36 includes a turret 364 and a plurality of light-reducing filters 364a, 364b, 364c, 364d, 364e, and 364f arranged on the turret 364 and having different light-reducing rates (transmittances). The light-reducing filters 364a to 364f are made of, for example, a film including a metal layer. The light amount adjustment unit 36 may also include a portion 366 where the filter hole of the turret 364 is blocked for complete light blocking, and a portion 368 where no light-reducing filter is arranged in the filter hole of the turret 364 for complete transmission.

In another example, the illumination optical system 63 may have, for example, two neutral density filter plates, and may be configured so that the two neutral density filter plates can be used in combination. Such a configuration allows the light attenuation rate to be set more precisely. Also, while FIG. 5 shows a configuration of the light amount adjustment unit 36 in which multiple neutral density filters are arranged on a turret, this is not limiting. For example, the light amount adjustment unit 36 may be configured to rotate a disk-shaped variable neutral density filter whose light attenuation rate changes continuously in the circumferential direction.

The light from the pattern 72 passes through the objective optical system 71, passes through the λ/4 plate 70, is converted from circularly polarized light to S-polarized light, and enters the aperture stop 69. Here, the light from the pattern 72 includes light reflected, diffracted, or scattered by the pattern 72. The polarization state of the light from the pattern 72 is circularly polarized in the opposite direction to the circularly polarized light illuminating the pattern 72. Therefore, if the polarization state of the light illuminating the pattern 72 is right-handed circularly polarized, the polarization state of the light from the pattern 72 is left-handed circularly polarized. The light that passes through the aperture stop 69 is reflected by the beam splitter 68, and enters the detection unit 75 via the imaging optical system 74.

In this way, in the measurement unit 50, the beam splitter 68 separates the optical path of the light illuminating the substrate 73 from the optical path of the light from the substrate 73, and an image of the pattern 72 is formed in the detection unit 75. The control unit 1100 then obtains the positions of the pattern elements that make up the pattern 72 and the position of the pattern 72 based on the position information of the substrate stage WS obtained by the laser interferometer 81 and the waveform of the detection signal obtained by detecting the image of the pattern 72.

Here, the measurement unit 50 may be configured to split the light emitted from the illumination unit 301 so that the emitted light enters a spectroscope (not shown). This allows the spectroscope to measure the spectral intensity of the light emitted from the illumination unit 301.

Figure 4 is a diagram showing the relationship between the wavelength and intensity of light transmitted through the wavelength variable unit 340. Figure 4 shows the relationship between the wavelength and intensity of light transmitted through the wavelength variable unit 340 when the wavelength variable unit 340 is arranged at multiple discrete positions in the X direction. The position at which light is incident changes depending on the position of the wavelength variable unit 340, and the wavelength of the light transmitted through the wavelength variable unit 340 changes. Here, since the absolute position of the light incident on the wavelength variable unit 340 does not change in the measurement unit 50, the wavelength driving unit 341 drives the wavelength variable unit 340, and the relative position of the light incident on the wavelength variable unit 340 changes. Therefore, in the illumination unit 301 shown in Figure 3, the wavelength driving unit 341 drives the wavelength variable unit 340 in the X direction, and the position of the wavelength variable unit 340 changes with respect to the incident light. This makes it possible to adjust the wavelength of the light illuminating the substrate 73.

Up to now, the wavelength tunable element of the wavelength tunable unit 340 has wavelength characteristics that change in a linear direction, but this is not limited to this. For example, the wavelength tunable unit 340 may be configured to rotate a disk-shaped wavelength tunable element whose wavelength characteristics change in the circumferential direction. In this case, the circumferential direction can be considered to be the drive direction.

The wavelength variable unit 340 may have a wavelength characteristic that changes linearly or nonlinearly depending on the position where the light is incident. Furthermore, the wavelength variable unit 340 may have a plurality of wavelength variable units (wavelength variable elements). For example, the wavelength variable unit 340 includes a first wavelength variable unit and a second wavelength variable unit. The first wavelength variable unit is, for example, a short wavelength pass filter (low pass filter, short pass filter) that transmits light with a wavelength shorter than a predetermined wavelength. The second wavelength variable unit is, for example, a long wavelength pass filter (high pass filter, long pass filter) that transmits light with a wavelength longer than a predetermined wavelength. By using a combination of a short wavelength pass filter and a long wavelength pass filter, the illumination unit 301 can illuminate light with an arbitrary center wavelength and an arbitrary wavelength width.

When the wavelength of the light illuminating the pattern 72 is switched, the reflectance of the process and the spectral characteristics of the optical system (light source power, sensor sensitivity, lens transmittance, etc.) change depending on the wavelength. Therefore, light amount adjustment (dimming) is required. The dimming of the light illuminating the pattern 72 can be performed by selecting a dimming filter in the light amount adjustment unit, controlling the output of the light source 361, controlling the accumulation time of the detection unit 75, etc. However, when the wavelength of the light illuminating the pattern 72 is switched, the light illuminating the pattern 72 is generally dimmed by selecting a dimming filter in the light amount adjustment unit. This is because the control of the output of the light source 361 (voltage adjustment, etc.) affects the life of the light source 361, and the control of the accumulation time of the detection unit 75 affects the throughput. Therefore, in a process in which the wavelength of the light illuminating the pattern 72 is frequently switched, it is necessary to precisely dim the light using a dimming filter to keep it within the light amount range detectable by the detection unit 75.

In conventional technology, in order to keep the amount of light illuminating the pattern within the range of light amounts detectable by the detection unit with a single dimming (i.e., to avoid readjustment), transmittance data is obtained that indicates the relationship between the transmittance of each neutral density filter and the wavelength band being used, and this data is used for dimming.

However, as in this embodiment, when a wavelength is selected using the wavelength variable unit 340, the wavelength band has an arbitrary center wavelength and an arbitrary wavelength width, and therefore the number of these wavelength bands cannot be limited (it is infinite). Therefore, it is not possible to establish a relationship between the wavelength band and the transmittance of the neutral density filter region, and it is not possible to obtain transmittance data in advance and adjust the light using that data.

In this embodiment, therefore, a simple optical system is realized, and a technology is provided that uses a variable wavelength filter to enable dimming of light in a wavelength band with an arbitrary center wavelength and an arbitrary wavelength width without the need for re-dimming.

A method for controlling the measurement device of this embodiment will be described with reference to FIG. 6. FIG. 6 is a flowchart for explaining the dimming operation by the measurement device 100 of this embodiment. Here, the dimming operation when switching from the first wavelength band to the second wavelength band will be described.

In S1, the control unit 1100 acquires the spectral intensity information 910 (see FIG. 8A) of the light (first light) emitted from the light source 361. At this time, the acquired spectral intensity information 910 is, for example, full-range spectral information. In order to make the wavelength band the same as that emitted from the light source 361, the wavelength driver 341 drives the wavelength variable unit 340 to a position where the wavelength of the light passing therethrough does not change. As described above, the wavelength variable unit 340 may include a full-pass region where the wavelength of the transmitted light passes through as is without changing it. The wavelength driver 341 drives the wavelength variable unit 340 so that the light (first light) irradiated from the light source 361 enters the full-pass region, thereby obtaining full-range spectral information. The spectral intensity information 910 may be measured, for example, using a spectrometer (not shown) configured inside the measurement device 100. Alternatively, the light emitted from the illumination unit 301 may be incident on a spectroscope disposed outside the measurement device 100, thereby measuring the spectral intensity information 910. The control unit 1100 acquires the spectral intensity information 910 from such an external spectroscope. Alternatively, the light source 361 may be caused to emit light before the illumination unit 301 is mounted on the measurement device 100, thereby measuring (acquiring) the spectral intensity information 910. Alternatively, the spectral intensity information 910 may be acquired based on the product specifications of the light source 361 provided by the manufacturer of the light source 361. The spectral intensity information 910 acquired in this manner is stored in the storage unit of the control unit 1100.

The spectral intensity information 910 may change in response to changes in the light source 361 over time. For this reason, it is desirable to reacquire the spectral intensity information 910 periodically or at specific times including when the measurement device is started up and reset. By reacquiring the spectral intensity information 910 at appropriate times to track changes in the light source 361 over time, it is possible to adjust the detection light using a neutral density filter with high precision.

The control unit 1100 may also detect the degree of change in the light source 361 based on the spectral intensity information 910 each time the control unit 1100 acquires the information. By knowing the degree of change in the light source 361, i.e., the state of deterioration, it is possible to know and prepare for the replacement of the light source 361, thereby reducing unintended downtime of the measurement device 100.

In S2, the control unit 1100 controls the detection unit 75 to obtain the amount of light (second light) from the pattern 72. At this time, the wavelength variable unit 340 is set to a position that transmits the first wavelength band. Also, the transmittance of the neutral density filter in the light amount adjustment unit 36 is set to the first transmittance (first adjustment amount). In S2, the detection unit 75 detects the amount of light in this state. The control unit 1100 stores the first detected light amount, which is the amount of light detected at this time, and the first transmittance, which is the transmittance of the neutral density filter, in the memory unit of the control unit 1100.

In S3, the control unit 1100 acquires first wavelength characteristic information 911 (see FIG. 8B) relating to the first wavelength band. The first wavelength characteristic information 911 is information on the first wavelength band portion of the spectral intensity information 910, i.e., the intensity integral value within the first wavelength bandwidth (first spectral intensity). The control unit 1100 calculates and stores the first wavelength characteristic information 911 relating to the first wavelength band from the spectral intensity information 910.

In S4, the control unit 1100 acquires second wavelength characteristic information 912 (see FIG. 8(c)) relating to the second wavelength band. The second wavelength characteristic information 912 is information on the second wavelength band portion of the spectral intensity information 910, i.e., the intensity integral value within the second wavelength bandwidth (second spectral intensity). The control unit 1100 calculates and stores the second wavelength characteristic information 912 relating to the second wavelength band from the spectral intensity information 910.

In S3 and S4, the first wavelength characteristic information 911 and the second wavelength characteristic information 912 are calculated, respectively, but the measurement light may be incident on a spectroscope (not shown) for measurement.

In S5, the control unit 1100 selects a neutral density filter to be used in the second wavelength band. For example, the control unit 1100 calculates the transmittance of the neutral density filter to be used in the second wavelength band based on the first detected light amount, the first transmittance, the first wavelength characteristic information, and the second wavelength characteristic information stored in the memory unit, and selects the neutral density filter closest to the calculated transmittance.

Here, the transmittance (second transmittance) of the dimming filter used when measuring the pattern in the second wavelength band is calculated by the following formula, which multiplies the amount of attenuation from the first wavelength characteristic information to the second wavelength characteristic information by the first transmittance.
Second transmittance = (first wavelength characteristic information/second wavelength characteristic information) x first transmittance

Figure 7 shows an example of wavelength characteristic information, neutral density filter transmittance, and sample values of detected light amount for each wavelength band. In Figure 7, the first transmittance obtained in S2 is 0.30, the first detected light amount is 90, the first wavelength characteristic information (intensity integral value) obtained in S3 is 2000, and the second wavelength characteristic information (intensity integral value) obtained in S4 is 800.

Here, in accordance with the above formula, the second transmittance calculated in S5 is
(2000/800) x 0.30 = 0.75
By setting the attenuation rate (second transmittance) of the neutral density filter used in the second wavelength band to 0.75, the amount of light when the second wavelength band is set can be made the same as the amount of light when the first wavelength band is set. In this way, the control unit 1100 determines the value obtained by multiplying the first transmittance (first adjustment amount) by the ratio between the first spectral intensity and the second spectral intensity as the second transmittance (second adjustment amount) in a state where the wavelength band of the first light is set to the second wavelength band.

As described above, the control unit 1100 acquires the first spectral intensity, which is the spectral intensity in the first wavelength band of the first light, and the second spectral intensity, which is the spectral intensity in the second wavelength band of the first light. Then, based on the acquired first and second spectral intensities, the control unit 1100 controls the light amount adjustment unit 36 when switching the wavelength band of the first light from the first wavelength band to the second wavelength band.

In the above example, the light illuminating the pattern 72 is adjusted by selecting a neutral density filter in the light amount adjustment unit 36, but it can also be adjusted by controlling the output of the light source 361 and the accumulation time of the detection unit 75.

In this way, in this embodiment, when using a variable wavelength filter to select an arbitrary wavelength band (center wavelength, wavelength width), it is possible to avoid spending time on dimming the detection light using a neutral density filter.

Second Embodiment
The second embodiment relates to a substrate processing apparatus to which the measurement apparatus described in the first embodiment is applied. Matters not mentioned here may follow the first embodiment. The substrate processing apparatus may be, for example, a lithography apparatus that forms a pattern on a substrate, such as an exposure apparatus or an imprint apparatus. Alternatively, the substrate processing apparatus may be an inspection apparatus, such as an overlay inspection apparatus, a CD inspection apparatus, a defect inspection apparatus, or an electrical characteristic inspection apparatus. Alternatively, the substrate processing apparatus may be a processing apparatus, such as an etching apparatus or a film formation apparatus. In the following, the substrate processing apparatus in the present disclosure will be described as an exposure apparatus, which is an example of a lithography apparatus.

The exposure apparatus according to this embodiment will be described with reference to FIG. 9. The exposure apparatus EXA is a lithography apparatus used in the lithography process, which is a manufacturing process for devices such as semiconductor elements and liquid crystal display elements, and forms a pattern on a substrate 73. The exposure apparatus EXA exposes the substrate 73 (wafer) through a reticle 31 (original, mask) to perform exposure processing (substrate processing) in which the pattern of the reticle 31 is transferred to the substrate 73.

Here, the reticle 31 is a reticle, original, or mask on which a predetermined pattern such as a circuit pattern is formed, and is made of, for example, quartz. The reticle 31 transmits light illuminated by an illumination optical system 91 described below. The substrate 73 is a processed object onto which the pattern of the reticle 31 is transferred, and is, for example, a silicon wafer, a glass plate, a film-like substrate, or another processed substrate. The substrate 73 is exposed to light while coated with photoresist, thereby transferring the pattern.

Here, an example will be described in which the exposure apparatus EXA is a scanning exposure apparatus (scanner) that exposes a pattern formed on the reticle 31 onto the substrate 73 while moving the reticle 31 and substrate 73 synchronously in the scanning direction. Note that this embodiment can also be applied to an exposure apparatus (stepper) of a type in which the reticle 31 is fixed and the reticle pattern is exposed onto the substrate 73.

The exposure apparatus EXA has a light source unit 90, an illumination optical system 91, a reticle stage RS, a projection optical system 32, a substrate stage WS, a measurement unit 50, and a control unit 1100.

The light source unit 90 includes at least one of a mercury lamp, a KrF excimer laser, and an ArF excimer laser. It may also include a light source of extreme ultraviolet light (EUV light) with a wavelength of several nm to a hundred nm.

The illumination optical system 91 shapes the light emitted from the light source unit 90 into a slit light having a predetermined shape optimal for exposure, and irradiates the reticle 31 held on the reticle stage RS with this light, illuminating a predetermined illumination area on the reticle 31. The illumination optical system 91 illuminates a predetermined illumination area on the reticle 31 with light having a uniform illuminance distribution. The illumination optical system 91 includes, for example, a lens, a mirror, an optical integrator, an aperture, etc., and is configured by arranging a condenser lens, a fly's-eye lens, an aperture aperture, a condenser lens, a slit, and an imaging optical system in this order.

The reticle stage RS moves while holding the reticle 31. The reticle stage RS can move, for example, within a plane perpendicular to the optical axis of the projection optical system 32, i.e., within the XY plane, and can rotate in the θZ direction. The reticle stage RS is driven by a driving device (not shown) such as a linear motor, which can be driven in three axial directions, X, Y, and θZ, and is controlled by the control unit 1100. Note that although the driving device is capable of driving in three axial directions, it may also be capable of driving in any one of one to six axial directions.

The projection optical system 32 irradiates the substrate 73 held by the substrate stage WS with light that has passed through the reticle 31, and projects an image of the pattern formed on the reticle 31 onto the substrate 73 at a predetermined projection magnification β. In this way, the substrate 73 is exposed to the light irradiated from the projection optical system 32, and a pattern is formed on the substrate 73. The projection optical system 32 is also composed of multiple optical elements, and the predetermined projection magnification β is, for example, 1/4 or 1/5.

Regarding the substrate stage WS, a description of the configuration common to the first embodiment will be omitted. A reference plate 39 equipped with a reference mark is installed on the substrate stage WS. The height of the surface of the reference plate 39 is determined to be the same height as the surface of the substrate 73 held by the substrate stage WS, and the measurement unit 50 also measures the position of the reference mark on the reference plate 39.

The control unit 1100 comprehensively controls each part of the exposure apparatus EXA, including the measurement device 100. The configuration of the control unit 1100 is the same as in the first embodiment, so a description thereof will be omitted. Also, the measurement unit 50 is the same as in the first embodiment, so a description thereof will be omitted.

Next, the exposure process according to this embodiment will be described with reference to FIG. 10. The exposure process shown in FIG. 10 is performed by the control unit 1100 comprehensively controlling each part of the exposure apparatus EXA.

In S101, the control unit 1100 causes the exposure apparatus EXA to load the substrate 73. In S102, the control unit 1100 causes a shape measurement device (not shown) to detect the surface (height) of the substrate 73 and measure the surface shape of the entire area of the substrate 73.

In S103, the control unit 1100 performs calibration. Specifically, the control unit 1100 drives the substrate stage WS so that the reference mark is positioned on the optical axis of the measurement unit 50 based on the position of the reference mark provided on the reference plate 39. Next, the control unit 1100 measures the positional deviation of the reference mark relative to the optical axis of the measurement unit 50, and based on the positional deviation, resets the coordinate system of the substrate stage WS so that the origin of the coordinate system of the substrate stage WS coincides with the optical axis of the measurement unit 50. Next, the control unit 1100 drives the substrate stage WS so that the reference mark is positioned on the optical axis of the exposure light based on the positional relationship between the optical axis of the measurement unit 50 and the optical axis of the projection optical system 32. Then, the control unit 1100 causes a TTL (through-the-lens) measurement system (not shown) to measure the positional deviation of the reference mark relative to the optical axis of the exposure light via the projection optical system 32. In S104, the control unit 1100 determines the baseline between the optical axis of the measurement unit 50 and the optical axis of the projection optical system 32 based on the results of the calibration in S103.

Here, in S103, a pattern measurement process is performed to measure the positional deviation of the reference mark. The control unit 1100 measures the pattern included in the reference mark using the measurement unit 50. The pattern measurement process may be performed, for example, every predetermined number of measurements or every predetermined number of substrates 73 that are subjected to the exposure process.

In S105, the control unit 1100 causes the measurement unit 50 to measure the position of the pattern 72 provided on the substrate 73. In S106, the control unit 1100 performs global alignment. Specifically, based on the measurement results in S105, the control unit 1100 calculates the shift, magnification, and rotation for the arrangement of the shot areas on the substrate 73, and determines the regularity of the arrangement of the shot areas. Then, a correction coefficient is calculated from the regularity of the arrangement of the shot areas and the baseline, and the substrate 73 is aligned with the reticle 31 (exposure light) based on the correction coefficient.

Here, in S105, a pattern measurement process is performed to measure the position of the pattern 72. The control unit 1100 measures the pattern 72 using the measurement unit 50. The pattern measurement process may be performed, for example, every predetermined number of measurements or every predetermined number of substrates 73 on which exposure processing is performed.

In S107, the control unit 1100 exposes the substrate 73 while controlling the reticle stage RS and the substrate stage WS to scan the reticle 31 and the substrate 73 in the scanning direction (Y direction). At this time, based on the surface shape of the substrate 73 measured by the shape measurement device, the control unit 1100 drives the substrate stage WS in the Z direction and tilt direction to sequentially align the surface of the substrate 73 with the imaging plane of the projection optical system 32.

In S108, the control unit 1100 determines whether exposure of all of the shot areas of the substrate 73 to be exposed has been completed (i.e., whether there are any unexposed shot areas among the shot areas to be exposed). If it is determined that exposure of all of the shot areas to be exposed has not been completed, the control unit 1100 transitions the process to S107. In other words, S107 and S108 are repeated until exposure of all of the shot areas to be exposed is completed. On the other hand, if it is determined that exposure of all of the shot areas to be exposed has been completed, the control unit 1100 transitions the process to S109. In S109, the control unit 1100 causes the substrate 73 to be removed from the exposure apparatus EXA.

<Embodiment of an article manufacturing method>
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 a microstructure. The article manufacturing method according to the present embodiment may include a step of processing a substrate using the above-mentioned substrate processing apparatus, and a step of manufacturing an article from the processed substrate. The step of manufacturing such an article may include other well-known steps (oxidation, film formation, deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The article manufacturing method according to the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article, as compared to conventional methods.

The disclosure of the present specification includes at least the following techniques.
(Item 1)
1. A measurement apparatus that measures a position of a pattern by detecting a second light from a pattern illuminated by a first light emitted from a light source, comprising:
a wavelength control unit that controls a wavelength of the first light by changing an incident position of the first light with respect to a wavelength tunable element;
a light amount adjustment unit that adjusts the amount of the first light whose wavelength is controlled by the wavelength control unit;
a control unit that controls the light amount adjustment unit when switching the wavelength band of the first light from the first wavelength band to the second wavelength band by the wavelength control unit, based on a first spectral intensity that is a spectral intensity in a first wavelength band of the first light and a second spectral intensity that is a spectral intensity in a second wavelength band of the first light;
A measuring device comprising:
(Item 2)
A detection unit that detects an amount of the second light,
The control unit is
acquire a first detected light amount, which is the amount of the second light detected by the detection unit in a state in which the wavelength band of the first light is set to the first wavelength band by the wavelength control unit and the adjustment amount by the light amount adjustment unit is set to a first adjustment amount;
determining a value obtained by multiplying the first adjustment amount by a ratio between the first spectral intensity and the second spectral intensity as a second adjustment amount, which is an adjustment amount by the light amount adjustment unit in a state in which the wavelength band of the first light is set to the second wavelength band by the wavelength control unit;
2. The measuring device according to item 1,
(Item 3)
2. The measurement apparatus according to claim 1, wherein the control unit acquires the first spectral intensity and the second spectral intensity based on a spectral intensity of the first light.
(Item 4)
a spectrometer that measures a spectral intensity of the first light,
The control unit acquires a spectral intensity of the first light from the spectroscope.
4. The measuring device according to item 3,
(Item 5)
The first light is incident on a spectrometer disposed outside the measurement device,
The control unit acquires a spectral intensity of the first light from the spectroscope.
4. The measuring device according to item 3,
(Item 6)
4. The measurement apparatus according to claim 3, wherein the control unit obtains the spectral intensity of the first light based on a product specification of the light source.
(Item 7)
7. The measurement apparatus according to claim 3, wherein the control unit periodically acquires the spectral intensity of the first light.
(Item 8)
7. The measurement device according to claim 3, wherein the control unit acquires the spectral intensity of the first light at a specific timing including a time when the measurement device is started and a time when the measurement device is reset.
(Item 9)
9. The measurement apparatus according to item 7 or 8, wherein the control unit detects a degree of change in the light source based on the acquired spectral intensity each time the control unit acquires the spectral intensity of the first light.
(Item 10)
A control method for a measurement device that measures a position of a pattern by detecting second light from the pattern illuminated with first light emitted from a light source, the measurement device including a wavelength control unit that controls a wavelength of the first light by changing an incident position of the first light with respect to a wavelength tunable element, and a light amount adjustment unit that adjusts an amount of the first light whose wavelength has been controlled by the wavelength control unit, the control method comprising:
acquiring a first spectral intensity, the first light being a spectral intensity in a first wavelength band;
acquiring a second spectral intensity, the second spectral intensity being a spectral intensity in a second wavelength band of the first light;
controlling the light amount adjustment unit when switching the wavelength band of the first light from the first wavelength band to a second wavelength band by the wavelength control unit based on the first spectral intensity and the second spectral intensity;
A control method comprising the steps of:
(Item 11)
A substrate processing apparatus for processing a substrate on which a pattern is formed, comprising:
A measuring device according to any one of items 1 to 9,
a substrate processing apparatus for processing the substrate aligned based on the position of the pattern measured by the measuring apparatus;
(Item 12)
Processing a substrate using the substrate processing apparatus according to item 11;
producing an article from the processed substrate;
A method for manufacturing an article, comprising:

The invention is not limited to the above-described embodiment, and various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the following claims are appended to disclose the scope of the invention.

100: Measuring device, 73: Substrate, 50: Measuring unit, 1100: Control unit, 340: Wavelength variable unit, 36: Light amount adjustment unit

Claims (12)

1. A measurement apparatus that measures a position of a pattern by detecting a second light from a pattern illuminated by a first light emitted from a light source, comprising:
a wavelength control unit that controls a wavelength of the first light by changing an incident position of the first light with respect to a wavelength tunable element;
a light amount adjustment unit that adjusts the amount of the first light whose wavelength is controlled by the wavelength control unit;
a control unit that controls the light amount adjustment unit when switching the wavelength band of the first light from the first wavelength band to the second wavelength band by the wavelength control unit, based on a first spectral intensity that is a spectral intensity in a first wavelength band of the first light and a second spectral intensity that is a spectral intensity in a second wavelength band of the first light;
A measuring device comprising: A detection unit that detects an amount of the second light,
The control unit is
acquire a first detected light amount, which is the amount of the second light detected by the detection unit in a state in which the wavelength band of the first light is set to the first wavelength band by the wavelength control unit and the adjustment amount by the light amount adjustment unit is set to a first adjustment amount;
determining a value obtained by multiplying the first adjustment amount by a ratio between the first spectral intensity and the second spectral intensity as a second adjustment amount, which is an adjustment amount by the light amount adjustment unit in a state in which the wavelength band of the first light is set to the second wavelength band by the wavelength control unit;
2. The measuring device according to claim 1 . The measurement device according to claim 1, characterized in that the control unit acquires the first spectral intensity and the second spectral intensity based on the spectral intensity of the first light. a spectrometer that measures a spectral intensity of the first light,
The control unit acquires a spectral intensity of the first light from the spectroscope.
4. The measuring device according to claim 3. The first light is incident on a spectrometer disposed outside the measurement device,
The control unit acquires a spectral intensity of the first light from the spectroscope.
4. The measuring device according to claim 3. The measurement device according to claim 3, characterized in that the control unit acquires the spectral intensity of the first light based on the product specifications of the light source. The measurement device according to claim 3, characterized in that the control unit periodically acquires the spectral intensity of the first light. The measurement device according to claim 3, characterized in that the control unit acquires the spectral intensity of the first light at specific times including when the measurement device is started and when it is reset. The measurement device according to claim 7, characterized in that the control unit detects the degree of change in the light source based on the acquired spectral intensity each time the spectral intensity of the first light is acquired. A control method for a measurement device that measures a position of a pattern by detecting second light from the pattern illuminated with first light emitted from a light source, the measurement device including a wavelength control unit that controls a wavelength of the first light by changing an incident position of the first light with respect to a wavelength tunable element, and a light amount adjustment unit that adjusts an amount of the first light whose wavelength has been controlled by the wavelength control unit, the control method comprising:
acquiring a first spectral intensity, the first light being a spectral intensity in a first wavelength band;
acquiring a second spectral intensity, the second spectral intensity being a spectral intensity in a second wavelength band of the first light;
controlling the light amount adjustment unit when switching the wavelength band of the first light from the first wavelength band to a second wavelength band by the wavelength control unit based on the first spectral intensity and the second spectral intensity;
A control method comprising the steps of: A substrate processing apparatus for processing a substrate on which a pattern is formed, comprising:
A measuring device according to any one of claims 1 to 9,
a substrate processing apparatus for processing the substrate aligned based on the position of the pattern measured by the measuring apparatus; A step of processing a substrate using the substrate processing apparatus according to claim 11;
producing an article from the processed substrate;
A method for manufacturing an article, comprising:

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