Lighting device and lighting method

Abstract

To provide an illumination device and a method for illumination which can evenly illuminate a vision region detected by a detector.SOLUTION: An illumination device 600 according to the present disclosure includes: a driving unit 620 for driving an optical member 610 so that an illumination light L1 scans a vision region 511 of a region extending in one direction of a sample 500; and a control unit 630 for controlling the driving unit 620 so that the scan of the illumination light L1 is in synchronization with transfer of a TDI sensor which receives light from the vision region 511 illuminated by the illumination light L1.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a lighting device and a lighting method.

Background Art

[0002] Patent Documents 1 to 3 describe inspection devices for defects generated in semiconductor substrates and photomasks.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] In mask defect inspection using EUV (Extreme Ultra Violet) light, it is necessary to uniformly and efficiently illuminate the inspection area of the sample. When an LPP (Laser Produced Plasma) method is used for the EUV light source that generates EUV light and a critical illumination configuration is adopted in the illumination optical system, the condensing profile of the laser light is directly reflected in the illumination profile.

[0005] For example, in the LPP method, the intensity distribution of the cross-section perpendicular to the optical axis of the laser beam that excites the target has a Gaussian profile. Therefore, in order to uniformly illuminate the field of view on a sample detected by a horizontally elongated sensor surface of a sensor such as a camera with illumination light having a horizontally elongated, flat profile, it is necessary to construct a complex optical system. For example, it is possible to form illumination light with a nearly flat illumination profile by beam splitting a single focused beam using a cylindrical lens and a quartz plate. This makes it possible to shape the illumination light to cover the field of view. However, this makes the optical system complex, and the amount of light that spills outside the field of view also increases, making it inefficient.

[0006] Patent Document 4 has the disadvantage that the illumination NA distribution varies depending on the position, so a method of scanning on the light source side is preferable.

[0007] The purpose of this disclosure is to solve such problems and to provide an illumination device and illumination method that can uniformly illuminate the field of view detected by the detector. [Means for solving the problem]

[0008] The illumination device according to this disclosure includes a drive unit that drives an optical member so that illumination light scans a field of view region of a sample extending in one direction in the said one direction, and a control unit that controls the drive unit so as to synchronize the scanning of the illumination light with the integration period of a TDI sensor that receives light from the field of view region illuminated by the illumination light.

[0009] In the above-described lighting device, the illumination light includes EUV light generated from plasma produced by irradiating a target with laser light, the optical member includes a mirror that reflects the laser light to the target, and the drive unit may cause the illumination light to scan in one direction within the field of view by driving the optical member so that the laser light scans the target in a predetermined direction.

[0010] In the above-described lighting device, the drive unit may drive the optical member such that the relationship between the position and time of the laser beam on the target includes a triangular wave.

[0011] In the above-described lighting device, the drive unit may drive the optical member such that the relationship between the position and time of the laser light on the target includes a wave obtained by superimposing at least one of a triangular wave, a sine wave, and a square wave.

[0012] In the above-described lighting device, the spot of illumination light in the field of view may be circular.

[0013] In the above-described lighting device, the spot of illumination light in the field of view may be elliptical in shape, with its major axis extending in a direction perpendicular to the other direction.

[0014] In the above-described illumination device, the optical member includes at least one of a mirror that reflects the illumination light toward the sample, a beam shifter that shifts the illumination position of the illumination light, and an acousto-optic element that shifts the illumination position of the illumination light, and the drive unit may drive the optical member so that the illumination light scans in one direction within the field of view.

[0015] The illumination device according to this disclosure includes a drive unit that drives an optical member so that the illumination light scans a field of view of a region extending in one direction in a sample in the said one direction, and a control unit that controls the drive unit so that the illumination light scans more times than a predetermined number of times in one integration cycle of a TDI sensor that receives light from the field of view illuminated by the illumination light.

[0016] The illumination method according to this disclosure comprises the steps of: driving an optical member so that illumination light scans a field of view of a region extending in one direction in a sample in the said one direction; and synchronizing the scanning of the illumination light with the integration period of a TDI sensor that receives light from the field of view illuminated by the illumination light.

[0017] In the above illumination method, the illumination light includes EUV light generated from a plasma generated by irradiating a target with laser light. The optical member includes a mirror that reflects the laser light toward the target. In the step of driving the optical member, the illumination light may be scanned in the one direction in the visual field region by driving the optical member so that the laser light scans the target in a predetermined direction.

[0018] In the above illumination method, in the step of driving the optical member, the optical member may be driven so that the relationship between the position and time of the laser light on the target includes a triangular wave.

[0019] In the above illumination method, in the step of driving the optical member, the optical member may be driven so that the relationship between the position and time of the laser light on the target includes a wave obtained by superimposing at least any one of a triangular wave, a sine wave, and a rectangular wave.

[0020] In the above illumination method, the spot of the illumination light in the visual field region may be circular.

[0021] In the above illumination method, the spot of the illumination light in the visual field region may be an ellipse having a major axis extending in a direction orthogonal to the one direction.

[0022] In the above illumination method, the optical member includes at least any one of a mirror that reflects the illumination light toward the sample, a beam shifter that shifts the illumination position of the illumination light, and an acousto-optic element that shifts the illumination position of the illumination light. In the step of driving the optical member, the optical member may be driven so that the illumination light scans in the one direction in the visual field region.

[0023] The above illumination device may further include a light source control unit that changes the intensity of the illumination light so as to be synchronized with the integration period of the TDI sensor.

[0024] In the above lighting method, a step of changing the intensity of the illumination light may be further provided so as to be synchronized with the integration period of the TDI sensor.

[0025] The lighting method according to the present disclosure includes a step of driving an optical member so that illumination light scans a visual field area of a region extending in one direction in a sample in the one direction, and a step of scanning the illumination light more times than a predetermined plurality of scans in one integration period of a TDI sensor that receives light from the visual field area illuminated by the illumination light.

Effect of the Invention

[0026] According to the present disclosure, it is possible to provide a lighting device and a lighting method capable of uniformly illuminating a visual field area detected by a detector.

Brief Description of the Drawings

[0027] [Figure 1] It is a cross-sectional view illustrating a light source according to Embodiment 1. <00001'09>It is a perspective view illustrating a container of a light source according to Embodiment 1. <00'00110> [Figure 3] It is a configuration diagram illustrating an inspection device according to Embodiment 1. [Figure 4] It is a configuration diagram illustrating a lighting device according to Embodiment 1. [Figure 5] It is a diagram illustrating the scanning of laser light and the movement of plasma on a target according to Embodiment 1. [Figure 6] It is a diagram illustrating the scanning of illumination light and the movement of reflected light in a visual field area on a sample according to Embodiment 1. [Figure 7] It is a diagram illustrating the movement of reflected light from a visual field area on a detection surface according to Embodiment 1. [Figure 8] It is a graph illustrating a triangular wave according to Embodiment 1, where the horizontal axis represents time and the vertical axis represents amplitude. [Figure 9]This graph illustrates the plasma profile on a target when the relationship between the position and time of the laser beam on the target according to Embodiment 1 is controlled to include triangular waves. The horizontal axis represents the position on the target, and the vertical axis represents the intensity of the EUV light generated from the plasma. [Figure 10] This graph illustrates the illumination light profile on a sample when the relationship between the position and time of the laser light on the target according to Embodiment 1 is controlled to include a triangular wave. The horizontal axis represents the position on the sample, and the vertical axis represents the intensity of the illumination light. [Figure 11] This graph illustrates a sine wave according to Embodiment 1, with the horizontal axis representing time and the vertical axis representing amplitude. [Figure 12] This graph illustrates the plasma profile on a target when the relationship between the position and time of the laser beam on the target according to Embodiment 1 is controlled to include a sine wave. The horizontal axis represents the position on the target, and the vertical axis represents the intensity of the EUV light generated from the plasma. [Figure 13] This graph illustrates the illumination light profile on a sample when the relationship between the position and time of the laser light on the target according to Embodiment 1 is controlled to include a sine wave. The horizontal axis represents the position on the sample, and the vertical axis represents the intensity of the illumination light. [Figure 14] This figure illustrates the shape of the spot of reflected light from the field of view on the detection surface according to Embodiment 1. [Figure 15] This figure illustrates the movement of reflected light from the field of view area on the detection surface according to Embodiment 1. [Figure 16] This figure illustrates the shape of the spot of reflected light from the field of view on the detection surface in another example of Embodiment 1. [Figure 17] This figure illustrates the movement of reflected light from the field of view area on the detection surface in another example of Embodiment 1. [Figure 18] This is a block diagram illustrating the control unit in the lighting device according to Embodiment 1. [Figure 19] This is a flowchart illustrating an example of the lighting method according to Embodiment 1. [Figure 20]This is a diagram illustrating a lighting device according to Embodiment 2. [Figure 21] This figure illustrates a lighting device according to Embodiment 4. [Figure 22] This figure illustrates the correspondence between the relative intensity of the laser light and the intensity profile of the illumination light when the laser light is scanned in the illumination device of the comparative example. [Figure 23] This figure illustrates the correspondence between the relative intensity of the laser light and the intensity profile of the illumination light when the laser light is scanned in the illumination device according to Embodiment 4. [Figure 24] This figure illustrates an optical element driven by the drive unit in the lighting device according to Embodiment 5. [Figure 25] This figure illustrates an optical element driven by the drive unit in the lighting device according to Embodiment 5. [Modes for carrying out the invention]

[0028] The specific configuration of this embodiment will be described below with reference to the drawings. The following description illustrates preferred embodiments of the present disclosure, and the scope of the present disclosure is not limited to the following embodiments. In the following description, the same reference numerals indicate substantially the same components.

[0029] (Embodiment 1) The illumination device according to Embodiment 1 will now be described. The illumination device of this embodiment generates illumination light used in optical devices such as inspection equipment. The illumination device generates illumination light suitable for optical devices when installed on a light source. Alternatively, the illumination device may generate illumination light suitable for optical devices when installed on an optical device. Before describing the illumination device, the <light source> and <optical device> will be described. Then, the <illumination device> will be described. This will make the illumination device clearer.

[0030] <Light source> The light source generates illumination light used in the optical device. If the optical device is an inspection device, the light source generates illumination light to illuminate the object to be inspected in the inspection device. If the optical device is an exposure device, the light source may also generate exposure light for the exposure device. As an example of a light source, an example in which molten metal held in a container is used as the target will be explained. Note that the light source is not limited to targeting molten metal held in a container, but may also target solid metals, liquid droplets, etc., that generate plasma when irradiated with laser light.

[0031] Figure 1 is a cross-sectional view illustrating a light source according to Embodiment 1. Figure 2 is a perspective view illustrating a container for the light source according to Embodiment 1. As shown in Figures 1 and 2, the light source 100 includes a container 111. The container 111 is, for example, a crucible, and can melt metal inside. The container 111 holds a target 112, such as molten metal, which generates plasma 127 when irradiated with laser light LR. The target 112 is, for example, the molten metal held in the container 111. Note that the target 112 is not limited to the molten metal held in the container 111, but may be a solid metal, a liquid droplet, etc., as long as it generates plasma 127 when irradiated with laser light LR. The molten metal is, for example, molten tin (Sn) or lithium (Li), but is not limited to tin or lithium as long as it generates plasma 127 when irradiated with laser light LR.

[0032] The container 111 has a rotation axis R and rotates about the rotation axis R. The container 111 is, for example, cylindrical with one opening closed. The closed portion of the container 111 is called the bottom 113. The cylindrical portion of the container 111 is called the cylindrical portion 114. The rotation axis R of the container 111 extends, for example, in the vertical direction. The inner surface of the bottom 113 is called the bottom surface 115. The inner surface of the cylindrical portion 114 is called the inner circumferential surface 116. A groove 117 may be formed at the joint between the bottom 113 and the cylindrical portion 114.

[0033] The inner circumferential surface 116, formed to surround the rotation axis R, may include a cylindrical portion at a constant distance from the rotation axis R, or it may include a mortar-shaped portion that widens outward towards the top. For example, the mortar-shaped portion of the inner circumferential surface 116 is connected to a groove 117.

[0034] The light source 100 may include a heater 118, a debris shield 119, and a collector mirror 120 in addition to the container 111. Heating by the heater 118 can form a target 112 such as molten metal inside the container 111. The collector mirror 120 reflects the generated EUV light LE. The EUV light LE is generated from the plasma 127 produced when laser light LR is irradiated onto the target 112. The debris shield 119 is positioned in the opening 121 so as to cover the target 112.

[0035] The light source 100 may include an excitation laser LS that generates laser light LR, or it may introduce laser light LR from an excitation laser LS installed outside the light source 100 to irradiate the target 112. The laser light LR is, for example, IR laser light. The laser light LR irradiates the target 112 under the control of the illumination device 600. For example, the laser light LR is reflected by the optical member 610 of the illumination device 600 and focused by the focusing lens 611. In this way, the laser light LR irradiates the target 112. The EUV light generated from the plasma 127 generated in the target 112 is emitted as illumination light L1 to an optical device such as the inspection device 1. Therefore, the illumination light L1 may include EUV light LE generated from the plasma 127 generated by irradiating the target 112 with laser light LR. The illumination device 600 will be described later.

[0036] <Optical equipment> Next, we will explain optical devices. In the following explanation, we will use an inspection device as an example of an optical device.

[0037] Figure 3 is a diagram illustrating the configuration of an inspection apparatus according to Embodiment 1. As shown in Figure 3, the inspection apparatus 1 comprises an illumination optical system 200, a detection optical system 300, a detector 410, and an image processing unit 420. The inspection apparatus 1 may further include a light source 100. The inspection apparatus 1 is a device that inspects defects, etc., of a sample 500 using illumination light L1 generated by the light source 100. The sample 500 is, for example, an EUV mask. Note that the sample 500 is not limited to an EUV mask, but may also be a semiconductor substrate, etc.

[0038] The illumination optical system 200 includes an ellipsoidal mirror 210, an ellipsoidal mirror 220, and a recessed mirror 230. The detection optical system 300 includes a perforated concave mirror 310, a convex mirror 320, a plane mirror 330, and a concave mirror 340. The perforated concave mirror 310 and the convex mirror 320 constitute a Schwarzschild magnifying optical system.

[0039] The light source 100 generates illumination light L1. Illumination light L1 includes, for example, EUV light LE at 13.5 nm, the same as the exposure wavelength of the EUV mask that will become the sample 500. Note that illumination light L1 may also include light other than EUV light. The illumination light L1 generated from the light source 100 is reflected by the ellipsoidal mirror 210. The illumination light L1 reflected by the ellipsoidal mirror 210 travels while being focused and is focused at the focal point IF1. Therefore, the ellipsoidal mirror 210 reflects the illumination light L1 generated from the light source 100 as focused light. The focal point IF1 is located in a position conjugate to the upper surface 510 of the sample 500, such as the EUV mask, and the detection surface 411 of the detector 410.

[0040] The illumination light L1, after passing through the focal point IF1, spreads out as it travels and enters a reflecting mirror such as the ellipsoidal mirror 220. Therefore, the illumination light L1 reflected by the ellipsoidal mirror 210 enters the ellipsoidal mirror 220 as divergent light via the intermediate focal point IF1. The illumination light L1 that enters the ellipsoidal mirror 220 is reflected by the ellipsoidal mirror 220, travels while being focused, and enters the recessed mirror 230. In other words, the ellipsoidal mirror 220 reflects the incident illumination light L1 as focused light. The ellipsoidal mirror 220 then causes the illumination light L1 to enter the recessed mirror 230. The recessed mirror 230 is positioned directly above the EUV mask. The illumination light L1 that enters the recessed mirror 230 and is reflected enters the sample 500. Therefore, the recessed mirror 230 reflects the illumination light L1 reflected by the ellipsoidal mirror 220 onto the sample 500, thereby causing the illumination light L1 to enter the sample 500.

[0041] The ellipsoidal mirror 220 focuses the illumination light L1 onto the sample 500. The illumination optical system 200 is positioned so that when the illumination light L1 illuminates the sample 500, the image of the light source 100 is projected onto the upper surface 510 of the sample 500. Therefore, the illumination optical system 200 provides critical illumination. In this way, the illumination optical system 200 illuminates the sample 500, such as an EUV mask, using critical illumination provided by the illumination light L1 generated by the light source 100.

[0042] The sample 500 is placed on the stage 520. Here, the plane parallel to the upper surface 510 of the sample 500 is defined as the αβ plane, and the direction perpendicular to the αβ plane is defined as the γ axis. The illumination light L1 is incident on the sample 500 from a direction inclined from the γ axis. That is, the illumination light L1 is obliquely incident to illuminate the sample 500.

[0043] The stage 520 is a three-dimensional drive stage having a drive unit 530. The drive unit 530 can illuminate a desired area of ​​the sample 500 by moving the stage 520 in the αβ plane. Furthermore, the drive unit 530 can adjust the focus by moving the stage 520 in the γ axis direction.

[0044] Illumination light L1 from light source 100 illuminates the inspection area of ​​sample 500. The inspection area illuminated by illumination light L1 is, for example, 0.5 mm square. However, the inspection area is not limited to 0.5 mm square. Illumination light L1 is incident on sample 500 from a direction inclined with respect to the γ axis. The light from sample 500 illuminated by illumination light L1 is incident on the perforated concave mirror 310. In the following, the light from sample 500 illuminated by illumination light L1 will be described as reflected light L2. Note that the light incident on the perforated concave mirror 310 from sample 500 is not limited to reflected light L2, but may also include diffracted light, etc. The reflected light L2 reflected by sample 500 is incident on the perforated concave mirror 310. A hole 311 is provided in the center of the perforated concave mirror 310. The perforated concave mirror 310 focuses the reflected light L2 from the sample 500 and reflects the focused reflected light L2 as convergent light.

[0045] The reflected light L2 reflected by the perforated concave mirror 310 is incident on the convex mirror 320. The convex mirror 320 reflects the reflected light L12 reflected by the perforated concave mirror 310 towards the hole 311 of the perforated concave mirror 310. The reflected light L2 that has passed through the hole 311 is incident on the plane mirror 330. The plane mirror 330 causes the reflected light L2 reflected by the convex mirror 320 to be incident on the perforated concave mirror 310 as focused light through the hole 311. The reflected light L2 that has been incident on the plane mirror 330 is reflected by the plane mirror 330. The reflected light L2 reflected by the plane mirror 330 travels while being narrowed and is focused at the focal point IF2. Therefore, the plane mirror 330 reflects the incident reflected light L2 as focused light. The focal point IF2 is sometimes called the aperture diaphragm. The focusing point IF2 is located in a position conjugate to the upper surface 510 of the sample 500 and the detection surface 411 of the detector 410.

[0046] The reflected light L2, after passing through the focal point IF2, spreads out as it travels and enters the concave mirror 340. Therefore, the reflected light L2 reflected by the plane mirror 330 as focused light is incident on the concave mirror 340 as divergent light via the focal point IF2. The concave mirror 340 reflects the incident reflected light L2 as focused light towards the detector 410. The reflected light L2 reflected by the concave mirror 340 is detected by the detector 410. In this way, the detection optical system 300 focuses the reflected light L2 from the sample 500 illuminated by the illumination light L1 and guides the focused reflected light L2 to the detector 410.

[0047] The detector 410 may include a TDI (Time Delay Integration) sensor. The detector 410 receives light from the sample 500 illuminated by illumination light L1. The area on the sample 500 detected by the detector 410 is called the field of view 511. The detector 410 receives reflected light L2 from the field of view 511 illuminated by illumination light L1. The field of view 511 may be included in the inspection area illuminated by illumination light L1. The detector 410 acquires image data of the sample 500, such as an EUV mask. If the detector 410 includes a TDI sensor, the detector 410 includes a plurality of image sensors arranged in a line in one direction. The image sensors are, for example, CCDs (Charge Coupled Devices). However, the image sensors are not limited to CCDs. The plurality of image sensors in a TDI sensor will be described later.

[0048] Image data of the sample 500 acquired by the detector 410 is output to the image processing unit 420 and processed in the image processing unit 420. The image processing unit 420 may be an information processing device such as a server or a personal computer.

[0049] The reflected light L2 contains information about defects in the sample 500. The specularly reflected light of the illumination light L1 incident on the sample 500 from a direction tilted with respect to the γ axis is detected by the detection optical system 300. If a defect exists in the sample 500, the defect will be observed as a dark image. This observation method is called bright-field observation. Alternatively, the inspection device 1 may incident the illumination light L1 on the sample 500 from the γ axis and have it detected by the detection optical system 300. If a defect exists in the sample 500, the defect will be observed as a bright image. This observation method is called dark-field observation.

[0050] <Lighting equipment> Figure 4 is a diagram illustrating the configuration of an illumination device according to Embodiment 1. As shown in Figures 1 and 4, the illumination device 600 comprises an optical element 610, a drive unit 620, and a control unit 630. The illumination device 600 may further include other optical elements such as a condensing lens 611.

[0051] The optical element 610 reflects the laser light LR generated by the excitation laser LS toward the target 112. Here, the plane parallel to the upper surface of the target 112 is defined as the XY plane, and the direction perpendicular to the XY plane is defined as the Z axis. The optical element 610 may include, for example, a mirror such as a piezo steering mirror. Note that the optical element 610 is not limited to a piezo steering mirror; it may also include a galvanometer mirror, a polygon mirror, etc., as long as it can reflect the laser light LR toward the target 112. The optical element 610 may also reflect the laser light LR toward the target 112 via a focusing lens 611.

[0052] The drive unit 620 is, for example, an actuator. The drive unit 620 drives the optical member 610 to change the reflection direction of the optical member 610. The drive unit 620 performs beam scanning by changing the angle of the optical member 610 with respect to the laser beam LR. Specifically, the drive unit 620 changes the reflective surface of the optical member 610 so that the laser beam LR scans the target 112 in a predetermined direction, for example, in the Y-axis direction. The drive unit 620 may also drive the optical member 610 so that the laser beam LR folds back on the Y-axis.

[0053] The control unit 630 controls the operation of the drive unit 620. Figure 5 illustrates the scanning of the laser beam LR on the target 112 and the movement of the plasma 127 according to Embodiment 1. As shown in Figures 4 and 5, the drive unit 620 drives the optical member 610 so that the laser beam LR scans the target 112 in the Y-axis direction. Therefore, the bright spots of the plasma 127 generated on the target 112 also move in the scanning direction (Y-axis direction). As a result, the intensity profile of the illumination light L1, which includes the EUV light LE generated from the plasma 127, extends in the scanning direction. The illumination light L1 illuminates the sample 500 via the illumination optical system 200. Therefore, the intensity profile of the illumination light L1 also extends in one direction on the sample 500.

[0054] Figure 6 illustrates the scanning of illumination light L1 and the movement of reflected light L2 in the field of view region 511 on the sample 500 according to Embodiment 1. As shown in Figure 6, the illumination light L1 is scanned in one direction, for example, in the β-axis direction, in the field of view region 511 on the sample 500 detected by the detector 410. The field of view region 511 is a region on the sample 500 that extends in the β-axis direction and is the region detected by the detection surface 411 of the detector 410. Thus, the drive unit 620 causes the illumination light L1 to scan in the β-axis direction in the field of view region 511 by driving the optical member 610 so that the laser light LR scans the target 112 in the Y-axis direction. In other words, the drive unit 620 drives the optical member 610 so that the illumination light L1 scans the field of view region 511 in the β-axis direction.

[0055] Figure 7 illustrates the movement of reflected light L2 from the field of view 511 on the detection surface 411 according to Embodiment 1. As shown in Figure 7, when the detector 410 includes a TDI sensor, the detector 410 has a plurality of image sensors M1 to M4 arranged in a line in one direction. The plurality of image sensors M1 to M4 arranged in a line are called an image sensor array. Therefore, the detector 410 has a plurality of image sensor arrays D1 to D5 arranged in a direction perpendicular to the one direction. Each image sensor array D1 to D5 includes a plurality of image sensors M1 to M4. Note that the number of image sensors shown in the figure is for illustrative purposes only and is illustrative.

[0056] The control unit 630 controls the scanning of the laser light LR on the target 112 to synchronize with the integration period of the TDI sensor. This allows the control unit 630 to control the drive unit 620 to synchronize the scanning of the illumination light L1 in the field of view 511 with the integration period of the TDI sensor. Specifically, the illumination light L1 that illuminates the sample 500 moves in the β-axis direction in synchronization with the integration period of the TDI sensor. The TDI sensor integrates the reflected light L2 received by the detection surface 411 during the transfer time t=t1~t5. For example, the integration period is the period during which the amount of reflected light L2 received by each image sensor M1~M4 of the multiple image sensor array D1~D5 on the detection surface 411 is integrated.

[0057] At time t=t1, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by the image sensor M1 in the image sensor array D1. Therefore, the image sensor M1 in the image sensor array D1 retains the amount of light it received.

[0058] At time t=t2, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by image sensors M1 and M2 in the image sensor array D2. Therefore, image sensors M1 and M2 in the image sensor array D2 retain the amount of light they received. Also, the amount of light held by image sensor M1 in the image sensor array D1 at time t=t1 is transferred to image sensor M1 in the image sensor array D2.

[0059] At time t=t3, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by image sensors M2 and M3 in the image sensor array D3. Therefore, image sensors M2 and M3 in the image sensor array D3 retain the amount of light they received. Also, the amount of light retained by image sensors M1 and M2 in the image sensor array D2 at time t=t2 is transferred to image sensors M1 and M2 in the image sensor array D3.

[0060] At time t=t4, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by image sensors M3 and M4 in the image sensor array D4. Therefore, image sensors M3 and M4 in the image sensor array D4 retain the amount of light they received. Also, at time t=t3, the amount of light retained by image sensors M1 to M3 in the image sensor array D3 is transferred to image sensors M1 to M3 in the image sensor array D4.

[0061] At time t=t5, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by the image sensor M4 in the image sensor array D5. Therefore, the image sensor M4 in the image sensor array D5 retains the amount of light it received. At time t=t4, the amount of light retained by the image sensors M1~M4 in the image sensor array D4 is transferred to the image sensors M1~M4 in the image sensor array D5. This completes the integration of the TDI sensor. This constitutes one integration cycle. During this time, the laser light LR scans the target 112 once in the Y-axis direction. Simultaneously, the illumination light L1 scans the field of view 511 once in the β-axis direction.

[0062] Furthermore, in one integration cycle, the laser beam LR may scan the target 112 two or more integer times in the Y-axis direction. Accordingly, the illumination beam L1 may scan the field of view 511 two or more integer times in the β-axis direction.

[0063] In this way, the control unit 630 operates the drive unit 620 in synchronization with the integration period of the TDI sensor. The control unit 630 causes the drive unit 620 to scan the field of view 511 one or more times, specifically an integer number of times, before the integration of the TDI sensor is completed. This makes it possible to illuminate the field of view 511 detected by the detector 410 with uniform illumination light L1. For example, this operation can be achieved by synchronizing the drive unit 620, such as a mirror actuator, with the clock of the TDI camera.

[0064] For example, if a TDI with 1000 stages is driven at a transfer rate of 100 kHz, the synchronization frequency will be 100 kHz / 1000 stages = 100 Hz. This is the frequency for round-trip scanning. Since a one-way scan is sufficient, the minimum required frequency is half of this, or 50 Hz. This is used as the minimum unit, and the bright spots of the plasma 127 are scanned at frequencies that are integer multiples of this value. This makes it possible to form illumination light L1 with an effectively flat luminance profile.

[0065] It is desirable that the illumination light L1 illuminating the field of view 511 moves at a constant velocity in the β-axis direction across the field of view 511. Therefore, it is desirable that the bright spot of the plasma 127 moves at a constant velocity in the Y-axis direction across the target 112. For example, the control unit 630 controls the operation of the drive unit 620 using a triangular wave.

[0066] Figure 8 is a graph illustrating a triangular wave according to Embodiment 1, where the horizontal axis represents time and the vertical axis represents amplitude. The vertical axis in Figure 8 shows the position of the laser beam LR in the Y-axis direction on the target 112. As shown in Figure 8, the control unit 630 controls the drive unit 620 so that the relationship between the position of the laser beam LR on the target 112 and time includes a triangular wave. As a result, the drive unit 620 drives the optical member 610 so that the relationship between the position of the laser beam LR on the target 112 and time includes a triangular wave. In other words, when the position in the Y-axis direction on the target 112 corresponds to the amplitude, the control unit 630 controls the position of the laser beam LR to scan at a constant speed in the Y-axis direction. As a result, a flat brightness profile of the plasma 127 can be formed on the target 112. Therefore, a flat illumination light L1 in the field of view region 511 Strength profile It is possible to form this.

[0067] The TDI sensor in detector 410 may integrate the amount of reflected light L2 when scanning the laser beam LR in the +Y axis direction, or it may integrate the amount of reflected light L2 when scanning the laser beam LR in the -Y axis direction. Alternatively, the TDI sensor in detector 410 may integrate the amount of reflected light L2 when scanning the laser beam LR in both the +Y axis direction and the -Y axis direction.

[0068] Figure 9 is a graph illustrating the profile of the plasma 127 on target 112 when the relationship between the position and time of the laser beam LR on target 112 according to Embodiment 1 is controlled to include a triangular wave, with the horizontal axis representing the position on target 112 and the vertical axis representing the intensity of the EUV light LE generated from plasma 127. Figure 10 is a graph illustrating the profile of the illumination light L1 on sample 500 when the relationship between the position and time of the laser beam LR on target 112 according to Embodiment 1 is controlled to include a triangular wave, with the horizontal axis representing the position on sample 500 and the vertical axis representing the intensity of the illumination light L1.

[0069] As shown in Figure 9, when the irradiation position of the laser beam LR is controlled to include a triangular wave, the profile of the plasma 127 on the target 112 can be made flat. However, as shown in Figure 10, the profile of the illumination light L1 on the sample 500 may deviate from flat. For example, the profile of the illumination light L1 on the sample 500 has a convex shape in the central part of the field of view 511 and a reduction at both ends of the field of view 511. This is thought to be due to a slope error caused by the repeated reflection and transmission of the illumination light L1 by the optical components of the illumination optical system 200. Therefore, the control unit 630 controls the operation of the drive unit 620 so that the relationship between the position and time of the laser beam LR on the target 112 includes a wave that is a superposition of a triangular wave and a sine wave. As a result, the drive unit 620 drives the optical component 610 so that the relationship between the position and time of the laser beam LR on the target 112 includes a wave that is a superposition of a triangular wave and a sine wave.

[0070] Figure 11 is a graph illustrating a sine wave according to Embodiment 1, where the horizontal axis represents time and the vertical axis represents amplitude. The vertical axis in Figure 11 shows the position of the laser beam LR in the Y-axis direction on the target 112. Figure 12 is a graph illustrating the profile of the plasma 127 on the target 112 when the relationship between the position and time of the laser beam LR on the target 112 according to Embodiment 1 is controlled to include a sine wave, where the horizontal axis represents the position on the target 112 and the vertical axis represents the intensity of the EUV light LE generated from the plasma 127. Figure 13 is a graph illustrating the profile of the illumination light L1 on the sample 500 when the relationship between the position and time of the laser beam LR on the target 112 according to Embodiment 1 is controlled to include a sine wave, where the horizontal axis represents the position on the sample 500 and the vertical axis represents the intensity of the illumination light L1.

[0071] As shown in Figures 11 and 12, when the irradiation position of the laser beam LR is controlled to include a sine wave, the profile of the plasma 127 on the target 112 has convex portions at both ends and a concave portion in the center. In the case of a sine wave, the speed of movement near the folding points at both ends decreases, so the profile has convex portions at both ends. As shown in Figure 13, when the irradiation position of the laser beam LR is controlled to include a sine wave, the difference between the convex portions at both ends and the concave portion in the center of the illumination light L1 profile on the sample 500 decreases. Therefore, by controlling the relationship between the position and time of the laser beam LR on the target 112 to include a wave that is a superposition of a triangular wave and a sine wave, the profile of the illumination light L1 on the sample 500 can be made closer to flat. In this way, by controlling the relationship between the position and time of the laser beam LR on the target 112 to include a wave that is a superposition of a triangular wave and a sine wave, the illumination light L1 on the sample 500 can be adjusted to be flat, taking slope error into account. The drive unit 620 may also drive the optical member 610 such that the relationship between the position and time of the laser beam LR on the target 112 includes a wave that is a superposition of at least one of a triangular wave, a sine wave, and a square wave.

[0072] Figure 14 illustrates the shape of the spot of reflected light L2 from the field of view area 511 on the detection surface 411 according to Embodiment 1. When the shape of the spot of laser light LR on the target 112 is circular, the shape of the spot of illumination light L1 in the field of view area 511 is also circular. As a result, as shown in Figure 14, the spot of reflected light L2 on the detection surface 411 of the detector 410 is also circular. The reflected light L2 from the field of view area 511 is received, for example, by image sensors M1 and M2 in image sensor arrays D1 to D5. In this case, image sensors M1 and M2 in image sensor array D1 each receive reflected light L2 with intensity I=1. Image sensors M1 and M2 in image sensor array D2 each receive reflected light L2 with intensity I=3. Image sensors M1 and M2 in image sensor array D3 each receive reflected light L2 with intensity I=5. Image sensors M1 and M2 in image sensor array D4 each receive reflected light L2 with intensity I=3. Image sensors M1 and M2 in image sensor array D5 each receive reflected light L2 with intensity I=1.

[0073] Figure 15 illustrates the movement of reflected light L2 from the field of view region 511 on the detection surface 411 according to Embodiment 1. As shown in Figure 15, at time t=t1, the reflected light L2 detected by the detector 410 including the TDI sensor is received by the image sensor M1 in the image sensor array D1. The image sensor M1 in the image sensor array D1 holds the amount of light with intensity I=1 that it received.

[0074] At time t=t2, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by image sensors M1 and M2 in the image sensor array D2. Therefore, image sensors M1 and M2 in the image sensor array D2 retain the received light intensity I=3. Also, the light intensity I=1 held by image sensor M1 in the image sensor array D1 at time t=t1 is transferred to image sensor M1 in the image sensor array D2. As a result, image sensor M1 in the image sensor array D2 retains a light intensity I=4.

[0075] At time t=t3, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by image sensors M2 and M3 in the image sensor array D3. Therefore, image sensors M2 and M3 in the image sensor array D3 retain the received light intensity I=5. Also, the light intensities I=4 and I=3, respectively, held by image sensors M1 and M2 in the image sensor array D2 at time t=t2 are transferred to image sensors M1 and M2 in the image sensor array D3. As a result, image sensor M2 in the image sensor array D3 retains a light intensity I=8. Image sensor M1 in the image sensor array D3 retains a light intensity I=4.

[0076] At time t=t4, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by image sensors M3 and M4 in the image sensor array D4. Therefore, image sensors M3 and M4 in the image sensor array D4 retain the received light intensity I=3. Also, the light intensity held by image sensors M1~M3 in the image sensor array D3 at time t=t3 is transferred to image sensors M1~M3 in the image sensor array D4. As a result, image sensor M3 in the image sensor array D4 retains a light intensity I=8. Image sensor M1 in the image sensor array D4 retains a light intensity I=4. Image sensor M2 in the image sensor array D4 retains a light intensity I=8.

[0077] At time t=t5, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by image sensor M4 in image sensor array D5. Therefore, image sensor M4 in image sensor array D5 holds the received light intensity I=1. Also, at time t=t4, the light intensity held by image sensors M1~M4 in image sensor array D4 is transferred to image sensors M1~M4 in image sensor array D5. As a result, image sensor M4 in image sensor array D5 holds a light intensity I=4. Image sensor M1 in image sensor array D5 holds a light intensity I=4. Image sensor M2 in image sensor array D5 holds a light intensity I=8. Image sensor M3 in image sensor array D5 holds a light intensity I=8. With this, the integration of the TDI sensor is completed, and the integration cycle ends.

[0078] When the number of scans is small, the intensity difference in the vertical direction (α-axis direction) of the illumination light L1 is converted into an intensity distribution in the horizontal direction (β-axis direction). Specifically, the intensity distribution of the illumination light L1 in the α-axis direction is converted into an intensity distribution in the β-axis direction of the image sensor array. Therefore, the spot of illumination light L1 in the field of view 511 is made vertically elongated, that is, elongated in the other direction (α-axis direction). This reduces the intensity difference in the β-axis direction.

[0079] Figure 16 illustrates the shape of the spot of reflected light L2 from the field of view 511 on the detection surface 411 according to another example of Embodiment 1. The shape of the spot of laser light LR on the target 112 is made vertically elongated. In this case, the shape of the spot of illumination light L1 in the field of view 511 is also vertically elongated. Specifically, the shape of the spot of illumination light L1 in the field of view 511 is an ellipse with its major axis extending in one direction (α-axis direction) orthogonal to one direction (β-axis direction). As a result, as shown in Figure 16, the spot of reflected light L2 on the detection surface 411 of the detector 410 is also vertically elongated.

[0080] Reflected light L2 from the field of view 511 is received, for example, by image sensors M1 and M2 in image sensor arrays D1 to D5. Image sensors M1 and M2 in image sensor array D1 each receive reflected light L2 with intensity I=3. Image sensors M1 and M2 in image sensor array D2 each receive reflected light L2 with intensity I=4. Image sensors M1 and M2 in image sensor array D3 each receive reflected light L2 with intensity I=5. Image sensors M1 and M2 in image sensor array D4 each receive reflected light L2 with intensity I=4. Image sensors M1 and M2 in image sensor array D5 each receive reflected light L2 with intensity I=4.

[0081] Figure 17 illustrates the movement of reflected light L2 from the field of view area 511 on the detection surface 411 according to another example of Embodiment 1. As shown in Figure 17, at time t=t1, the reflected light L2 detected by the detector 410 including the TDI sensor is received by the image sensor M1 in the image sensor array D1. The image sensor M1 in the image sensor array D1 holds the amount of light with intensity I=3 that it received.

[0082] At time t=t2, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by image sensors M1 and M2 in the image sensor array D2. Therefore, image sensors M1 and M2 in the image sensor array D2 retain the received light intensity I=4. Also, the light intensity I=3 held by image sensor M1 in the image sensor array D1 at time t=t1 is transferred to image sensor M1 in the image sensor array D2. As a result, image sensor M1 in the image sensor array D2 retains a light intensity I=7.

[0083] At time t=t3, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by image sensors M2 and M3 in the image sensor array D3. Therefore, image sensors M2 and M3 in the image sensor array D3 retain the received light intensity I=5. Also, the light intensities I=7 and I=4, respectively, held by image sensors M1 and M2 in the image sensor array D2 at time t=t2 are transferred to image sensors M1 and M2 in the image sensor array D3. As a result, image sensor M2 in the image sensor array D3 retains a light intensity I=9. Image sensor M1 in the image sensor array D3 retains a light intensity I=7.

[0084] At time t=t4, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by image sensors M3 and M4 in the image sensor array D4. Therefore, image sensors M3 and M4 in the image sensor array D4 retain the received light intensity I=4. Also, the light intensity held by image sensors M1~M3 in the image sensor array D3 at time t=t3 is transferred to image sensors M1~M3 in the image sensor array D4. As a result, image sensor M3 in the image sensor array D4 retains a light intensity I=9. Image sensor M1 in the image sensor array D4 retains a light intensity I=7. Image sensor M2 in the image sensor array D4 retains a light intensity I=9.

[0085] At time t=t5, the reflected light L2 detected by the detector 410, which includes the TDI sensor, is received by image sensor M4 in image sensor array D5. Therefore, image sensor M4 in image sensor array D5 holds the received light intensity I=3. Also, at time t=t4, the light intensity held by image sensors M1~M4 in image sensor array D4 is transferred to image sensors M1~M4 in image sensor array D5. As a result, image sensor M4 in image sensor array D5 holds a light intensity I=7. Image sensor M1 in image sensor array D5 holds a light intensity I=7. Image sensor M2 in image sensor array D5 holds a light intensity I=9. Image sensor M3 in image sensor array D5 holds a light intensity I=9. With this, the integration of the TDI sensor is completed, and the integration cycle ends.

[0086] When the spot shape of the illumination light L1 is circular, the light intensity of image sensors M2 and M3 is twice that of image sensors M1 and M4. That is, the ratio of light intensity between the center and the edges of the illumination light L1 in the field of view 511 is twice. In contrast, by making the spot shape of the illumination light L1 a vertically elongated ellipse, the light intensity of image sensors M2 and M3 is 1.2 times that of image sensors M1 and M4. Therefore, the ratio of light intensity between the center and the edges of the illumination light L1 in the field of view 511 can be reduced to 1.2 times. Thus, the field of view 511 can be illuminated more uniformly.

[0087] The control unit 630 may be, for example, an information processing device such as a server or a personal computer. Figure 18 is a block diagram illustrating the control unit 630 in the lighting device 600 according to Embodiment 1. As shown in Figure 18, the control unit 630 has a processing unit 631, a communication unit 632, a storage unit 633, and an interface unit 634. The processing unit 631, the communication unit 632, the storage unit 633, and the interface unit 634 each have the functions of a processing means, a communication means, a storage means, and an interface means, respectively.

[0088] The processing unit 631 includes, for example, a processor such as a CPU (Central Processing Unit), MPU (Micro Processing Unit), ECU (Electronic Control Unit), FPGA (Field-Programmable Gate Array), or ASIC (Application Specific Integrated Circuit). The processing unit 631 functions as an arithmetic unit that performs processing and calculations. The processing unit 631 also controls the operation of the communication unit 632, the storage unit 633, the interface unit 634, and each component that performs the functions of each device.

[0089] Each component of the control unit 630 can be realized, for example, by executing a program controlled by the processing unit 631. More specifically, each component can be realized by the processing unit 631 executing a program stored in the storage unit 633. Alternatively, each component may be realized by recording the necessary programs on any non-volatile recording medium and installing them as needed. Furthermore, each component is not limited to being realized by software programs, but may also be realized by any combination of hardware, firmware, and software.

[0090] The communication unit 632 performs the necessary communication for the control unit 630 to perform control. The storage unit 633 is, for example, ROM (Read Only Memory) or RAM (Random Access Memory). The storage unit 633 has the function of storing control programs and calculation programs executed by the processing unit 631.

[0091] The interface unit 634 is, for example, a user interface. The interface unit 634 is connected to input means such as a keyboard, touch panel, or mouse, and output means such as a display or speaker. The interface unit accepts data input operations from the user (operator, etc.) and outputs information to the user.

[0092] Next, the illumination method will be described. Figure 19 is a flowchart illustrating the illumination method according to Embodiment 1. As shown in step S10 of Figure 19, the optical member 610 is driven so that the illumination light L1 scans the field of view 511. Specifically, the control unit 630 drives the drive unit 620 to drive the optical member 610 so that the illumination light L1 scans the field of view 511 of the region of the sample 500 that extends in the β-axis direction in the β-axis direction.

[0093] Next, as shown in step S20, the scanning of the illumination light L1 is controlled to synchronize with the integration period of the TDI sensor. Specifically, the control unit 630 controls the scanning of the illumination light L1 to synchronize with the integration period of the TDI sensor that receives light from the field of view area 511 illuminated by the illumination light L1.

[0094] The illumination light L1 may include EUV light LE generated from plasma 127 created by irradiating the target 112 with laser light LR. The optical member 610 may include a mirror that reflects the laser light LR to the target 112. In step S10, which drives the optical member 610, the illumination light L1 may be scanned in the β-axis direction within the field of view 511 by driving the optical member 610 so that the laser light LR scans the target 112 in the Y-axis direction.

[0095] Furthermore, in step S10, in which the optical member 610 is driven, the optical member 610 may be driven such that the relationship between the position and time of the laser beam LR on the target 112 includes a triangular wave. Alternatively, the optical member 610 may be driven such that the relationship between the position and time of the laser beam LR on the target 112 includes a wave obtained by superimposing a triangular wave and a sine wave.

[0096] Next, the effects of this embodiment will be described. The illumination device 600 of this embodiment synchronizes the scanning of illumination light L1 in the field of view area 511 with the integration period of the TDI sensor. For example, the scanning of illumination light L1 is synchronized with the integration time of the TDI sensor. As a result, a uniform illumination profile covering the field of view area 511 can be achieved by the movement of the bright spot of the plasma 127 due to the scanning of the optical element 610 such as a mirror. Therefore, the field of view area 511 detected by the detector 410 can be illuminated uniformly.

[0097] Furthermore, by flattening the illumination profile in the field of view 511 and reducing the light intensity outside the field of view 511, the utilization efficiency of the illumination light L1 can be improved.

[0098] If the bright spot of plasma 127 can be made to move back and forth multiple times within one integration time, the effect of multi-stage integration can average out the brightness fluctuations from pulse to pulse, thereby improving stability.

[0099] When using multiple excitation lasers LS, it is possible to average out the differences in brightness of the illumination light L1 due to differences between machines.

[0100] By adjusting the stroke amount of the angle change of the optical element 610, the amount of light that extends outside the field of view 511 can be adjusted. Therefore, it is easy to make adjustments such as increasing the component outside the field of view 511 to increase the stability of the light amount, or adjusting the amount of movement to fill the field of view 511 to improve efficiency.

[0101] The drive unit 620 may generate EUV light LE by causing the laser light LR to scan the target 112, in which case illumination light L1 including EUV light LE can be used, and this can be applied to inspection equipment and exposure equipment using EUV light LE.

[0102] By scanning the optical element 610 according to a triangular wave, the profile of the illumination light L1 can be flattened. Furthermore, by scanning the optical element 610 according to a superposition of a triangular wave and a sine wave, the slope error of the illumination optical system 200 can be reduced. For example, since the illumination shape becomes blurred due to the slope error of the optical system, the illumination shape can be optimized by shifting the scan waveform from a triangular wave closer to a sine wave.

[0103] The intensity distribution in a cross-section perpendicular to the optical axis of the illumination light L1 can be a simple Gaussian profile, which simplifies the optical system.

[0104] If the scanning speed of the illumination light L1 is approximately the same as the integration period of the TDI sensor, the spot of illumination light L1 in the field of view 511 may be an ellipse with its major axis extending in the β-axis direction. This reduces the difference in intensity between the center and the edges of the illumination light L1 profile, thereby improving the uniformity of the illumination light L1.

[0105] (Embodiment 2) Next, an illumination device according to Embodiment 2 will be described. In this embodiment, instead of scanning an optical member 610 that reflects the laser light L1 toward the target 112, the illumination device scans a mirror that reflects the illumination light L1 toward the sample 500.

[0106] Figure 20 is a diagram illustrating an illumination device according to Embodiment 2. In the illumination device 600a of this embodiment, the drive unit 620 drives the recessed mirror 230 of the inspection device 2. In the illumination device 600a, the recessed mirror 230 corresponds to the optical member 610 of Embodiment 1. The recessed mirror 230 reflects the illumination light L1 onto the sample 500. The drive unit 620 drives the recessed mirror 230 so that the illumination light L1 scans in the β-axis direction within the field of view 511.

[0107] According to this embodiment, the illumination light L1 scans the field of view 511 by scanning the recessed mirror 230. Therefore, the responsiveness of the illumination light L1 scan can be improved. Furthermore, the scanned illumination light L1 does not pass through the illumination optical system 200. That is, the illumination light L1 directly scans the field of view 511. Therefore, the slope error of the illumination optical system 200 can be suppressed. In the illumination device 600a, a recessed mirror 230 was used as the optical element 610, but it is not limited to this. For example, a collector mirror 120, ellipsoidal mirrors 210 and 220, etc., may be used to scan the illumination light L1. Other configurations and effects are included in the description of Embodiment 1.

[0108] (Embodiment 3) Next, the illumination device of Embodiment 3 will be described. In the illumination device 600 of this embodiment, the control unit 630 controls the drive unit 620 to scan the illumination light L1 more times than a predetermined number of scans in one integration cycle of the TDI sensor. In this case, the laser light LR or illumination light L1 may be scanned by the optical member 610 without being synchronized with the integration cycle of the TDI sensor. If the scanning of the laser light LR or illumination light L1 is not synchronized with the integration cycle, the brightness will be calculated as scan count / (scan count + 1). Non-uniformity occurs Therefore, if the laser beam LR or illumination light L1 can be scanned at a sufficiently high speed, the non-uniformity of brightness can be relatively reduced. For example, by using a polygon mirror in the optical element 610, the laser beam LR or illumination light L1 can be scanned at high speed.

[0109] Thus, in this embodiment, the control unit 630 causes the TDI sensor, which receives light from the field of view area 511 illuminated by the illumination light L1, to scan the illumination light L1 more times than a predetermined number of scans in one integration cycle. The predetermined number of scans may be determined in advance by testing to find the number of scans at which the brightness non-uniformity becomes negligible.

[0110] (Embodiment 4) Next, the lighting device of Embodiment 4 will be described. In addition to optimizing the lighting shape by controlling the drive waveform of the drive unit 620 such as an actuator, it is also possible to generate flat lighting by modulating the intensity of the laser beam LR to correct the intensity distribution of the scan lighting. Furthermore, it is also possible to generate flat lighting by combining drive waveform control and laser beam intensity control.

[0111] Figure 21 is an illustrative diagram of the illumination device 600b according to Embodiment 4. As shown in Figure 21, the illumination device 600b of this embodiment further comprises a light source control unit 700. The light source control unit 700 controls the intensity of the laser light LR. For example, the light source control unit 700 controls the intensity of the laser light LR so as to be synchronized with the integration period of the TDI. This allows the light source control unit 700 to change the intensity of the illumination light L1 so as to be synchronized with the integration period of the TDI. Furthermore, the illumination method of this embodiment further comprises the step of changing the intensity of the illumination light L1 so as to be synchronized with the integration period of the TDI. This embodiment will be described below in comparison with comparative examples. First, comparative examples will be described.

[0112] Figure 22 illustrates the correspondence between the relative intensity of the laser beam LR (IR light) and the intensity profile of the illumination light (EUV light) when the laser beam LR is scanned in the illumination device according to the comparative example. As shown in Figure 22, in the comparative example, the laser beam LR is scanned while maintaining a constant relative intensity. In this case, the EUV light profile has a relatively low-intensity region and a relatively high-intensity region.

[0113] Next, the illumination device 600b of this embodiment will be described. Figure 23 is a diagram illustrating the correspondence between the relative intensity of the laser light LR (IR light) and the intensity profile of the illumination light (EUV light) when the laser light LR (IR light) is scanned in the illumination device 600b according to Embodiment 4. As shown in Figure 23, in this embodiment, the illumination device 600b includes a light source control unit 700 that controls the intensity of the laser light LR in the light source 100. The light source control unit 700 controls the intensity of the laser light LR so that it is relatively high in the central part of the scan, and so that it is relatively low in the folded-over part of the scan. In this case, the profile of the EUV light has a flat intensity portion.

[0114] In this way, the light source control unit 700 modulates the intensity of the laser beam LR to correct the intensity distribution of the scan illumination. This makes it possible to generate flat illumination. Specifically, the intensity of the laser beam LR is increased where the relative intensity of the illumination light is low, and decreased where the relative intensity of the illumination light is high. This makes it possible to generate flat illumination. It is also possible to generate flat illumination by combining the waveform control of the drive unit 620 described above with the intensity control of the laser beam LR in this embodiment. In particular, when the drive unit 620 such as an actuator is driven (scanned) at high speed, there is a risk that the responsiveness will be impaired. For this reason, controlling the intensity of the laser beam LR may be more advantageous in terms of tracking performance. Naturally, the intensity modulation of the laser beam LR must also be performed in synchronization with the TDI.

[0115] The intensity control of the laser beam L and R by the light source control unit 700 is not limited to controlling it to high intensity in the center of the scan and low intensity in the folded-over portion. The light source control unit 700 may perform any modulation control as long as it controls the intensity of the laser beam L and R to achieve flat illumination.

[0116] (Embodiment 5) Next, Embodiment 5 will be described. In this embodiment, instead of a mirror, a beam shifter and an AOM (acousto-optic element) are used as the optical element 610 driven by the drive unit 620.

[0117] Figures 24 and 25 illustrate an optical element 610 driven by the drive unit 620 in the illumination device 600c according to Embodiment 5. As shown in Figure 24, the optical element 610 may be a beam shifter 610a that shifts the irradiation position of the laser light LR. This allows the beam shifter 610a to scan the illumination position of the illumination light L1. Therefore, the drive unit 620 drives the beam shifter 610a so that the illumination light L1 scans within the field of view.

[0118] Furthermore, as shown in Figure 25, the optical element 610 may also be an AOM610b that shifts the irradiation position of the laser beam LR. This allows the AOM610b to scan the illumination position of the illumination light L1. Therefore, the drive unit 620 drives the AOM610b so that the illumination light L1 scans within the field of view.

[0119] (Embodiment 6) Next, Embodiment 6 will be described. In the illumination device 600 of this embodiment, the drive unit 620 drives the optical member 610 so that the illumination light L1 has a moving component that scans in one direction over a field of view area 511 extending in one direction over a sample 500. The control unit 630 controls the drive unit 620 so that the scanning of the unidirectional moving component of the illumination light L1 is synchronized with the integration period of the TDI sensor that receives light from the field of view area 511 illuminated by the illumination light L1. Note that the illumination light L1 may illuminate the field of view area 511 simultaneously with multiple spots, and the control unit 630 may control the drive unit 620 so that the scanning of the unidirectional moving component for each of the multiple spots of illumination light L1 (if there are an integer N spots, illumination light L11, illumination light L12, ... illumination light LN) is synchronized with the integration period of the TDI sensor.

[0120] Furthermore, it is sufficient that the scanning of the illumination light L1 with a unidirectional moving component (β direction in Figure 6) is synchronized with the integration period of the TDI sensor that receives light from the field of view 511 illuminated by the illumination light L1. During this time, the scanning of the illumination light L1 may also be accompanied by a moving component orthogonal to the unidirectional movement (α direction in Figure 6).

[0121] Furthermore, the shape of one or more illumination light L1 spots in the field of view 511 may be circular, elliptical, rectangular, linear, or other shapes. Two or more spots may be substantially the same shape or different shapes, and two or more spots may be arranged vertically or horizontally.

[0122] In this embodiment as well, the illumination light L1 may include EUV light LE generated from plasma 127 produced by irradiating the target 112 with laser light LR. In this case, the optical member 610 may define the irradiation position of the laser light LR onto the target 112. Specifically, the optical member 610 may define the irradiation position where the laser light LR emitted from the excitation laser LS irradiates the target 112 through the optical member 610. The illumination device 600 may include not only a single optical member 610 but also a plurality of optical members 610. The plurality of optical members 610 may define the irradiation position of the laser light LR onto the target 112. Note that the single or plurality of optical members 610 are not limited to mirrors such as piezo steering mirrors, galvanometer mirrors, and polygon mirrors, but may also include members that transmit laser light LR. Such laser light LR-transmitting optical members 610 may define the irradiation position of the laser light LR onto the target 112. Furthermore, one or more optical elements 610 may include, in addition to the mirrors that reflect the laser light LR and the elements that transmit the laser light LR as described above, at least one of the following: a beam shifter that shifts the irradiation position of the laser light LR, an acousto-optic element that shifts the irradiation position of the laser light LR, and an electro-optic element that changes the irradiation position of the laser light LR. Here, the electro-optic element includes an element that controls the path of light by utilizing a change in refractive index due to voltage, and includes, for example, a KTN optical scanner using a KTN crystal of an oxide crystal containing potassium, tantalum, and niobium.

[0123] One or more optical members 610 may define the position on the optical path from the plasma generation site 127 to the sample 500 where the EUV light LE irradiates the sample 500. In other words, similar to the function of defining the irradiation position of the laser light LR onto the target 112 as described above, the optical members 610 may define the position where illumination light L1, such as the EUV light LE, irradiates the sample 500. In this case, one or more optical members 610 may include at least one of the following, similar to the case of the laser light LR described above: a mirror that reflects the illumination light L1 onto the sample 500, a beam shifter that shifts the illumination position of the illumination light L1 onto the sample 500, an acousto-optic element that shifts the illumination position of the illumination light L1 onto the sample 500, and an electro-optic element that changes the illumination position of the illumination light L1 onto the sample 500.

[0124] The drive unit 620 drives the optical member 610 so that the laser beam LR has a moving component that scans the target 112 in a predetermined direction, thereby giving the illumination light L1 a moving component that scans in one direction. As described above, if the illumination device 600 includes multiple optical members 610, the drive unit 620 may give the illumination light L1 a moving component that scans in one direction by driving the multiple optical members 610. The moving component that causes the laser beam LR to scan the target 112 in a predetermined direction is sometimes called the laser beam moving component. This distinguishes the field of view region 511 of the sample 500 that extends in one direction from the moving component of the illumination light L1 that scans in one direction.

[0125] The TDI sensor may comprise multiple image sensor arrays, each having multiple image sensors. As mentioned above, the TDI sensor may transfer information between image sensors belonging to the same image sensor array. It is preferable that the direction in which the field of view 511 extends in the sample 500 (the β direction in Figure 6) is approximately the same as the direction in which the image sensor arrays are arranged (see Figures 15 and 17). That is, it is preferable that the scan direction (the β direction in Figure 6) and the orientation of the image sensors that transfer information to each other are orthogonal (see Figures 15 and 17). This allows the scanning of the illumination light L1 of the moving component in one direction to be synchronized with the integration period of the TDI sensor.

[0126] The control unit 630 controls the drive unit 620 so that the number of reciprocating scans performed in one cycle of the TDI sensor's integration period, consisting of the movement component on one side in one direction and the movement component on the other side in the same direction, is an integer. Here, one integration period of the TDI sensor may also be called the integration period of one cycle of the TDI sensor.

[0127] The illumination method of this embodiment includes the steps of: driving the optical member 610 so that the illumination light L1 has a moving component that scans in one direction over a field of view 511 extending in one direction over a sample 500; and synchronizing the scanning of the unidirectional moving component of the illumination light L1 with the integration period of a TDI sensor that receives light from the field of view 511 illuminated by the illumination light L1.

[0128] In the step of driving the optical member 610, the optical member 610 may be driven so that the laser beam LR has a laser beam movement component that scans the target 112 in a predetermined direction, thereby giving the illumination light LR a movement component that scans in one direction. Alternatively, in the step of driving the optical member 610, the number of round-trip scans performed in one cycle of the TDI sensor's integration period, consisting of the movement component on one side in one direction of the illumination light L1 and the movement component on the other side in the same direction, may be set to an integer. In addition, it is sufficient that the number of round-trip scans performed in one cycle of the TDI sensor's integration period, consisting of the movement component on one side in one direction of the illumination light L1 (for example, +β direction in Figure 6) and the movement component on the other side in the same direction (for example, -β direction in Figure 6), is an integer, and the scanning of the illumination light L1 may include a movement component that is orthogonal to one direction (α direction in Figure 6).

[0129] According to this embodiment, the scanning of the unidirectional moving component illumination light L1 can be synchronized with the integration period of the TDI sensor, so that the field of view region 511 detected by the detector 410 can be uniformly illuminated. Other configurations and effects are described in Embodiments 1 to 5.

[0130] (Embodiment 7) In the illumination device 600 of Embodiment 3 described above, the control unit 630 controls the drive unit 620 so that the illumination light L1 scans more times than a predetermined number of times in one integration cycle of the TDI sensor. In this embodiment, the drive unit 620 drives the optical member 610 so that the illumination light L1 has a moving component that scans in one direction over a field of view 511 of a region extending in one direction in the sample 500. The control unit 630 controls the drive unit 620 so that the illumination light L1 is scanned in one direction more times than a predetermined number of times in one integration cycle of the TDI sensor that receives light from the field of view 511 illuminated by the illumination light L1. With this configuration, similar to Embodiment 3, the non-uniformity of brightness can be relatively reduced. In this embodiment as well, the illumination light L1 may illuminate the field of view 511 with multiple spots simultaneously, and the control unit 630 may control the drive unit 620 so that the number of scans of the unidirectional movement component for each of the multiple spots of illumination light L1 (if there are an integer N spots, illumination light L11, illumination light L12, ... illumination light LN) is greater than a predetermined number in the integration cycle of the TDI sensor. Furthermore, the shape of one or more illumination light L1 spots in the field of view 511 may be circular, elliptical, rectangular, linear, or other shapes. The shapes of two or more spots may be substantially the same or different, and two or more spots may be arranged vertically or horizontally.

[0131] The illumination method of this embodiment includes the steps of: driving an optical member 610 so that the illumination light L1 has a moving component that scans in one direction over a field of view 511 extending in one direction over a region of the sample 500; and scanning the illumination light L1 in one direction more than a predetermined number of times within the cumulative period of one cycle of a TDI sensor that receives light from the field of view 511 illuminated by the illumination light L1. Configurations and effects of this embodiment other than those described above are included in the descriptions of Embodiments 1 to 6.

[0132] While embodiments of this disclosure have been described above, this disclosure includes appropriate modifications that do not impair its purpose and advantages, and is not limited by the embodiments described above. Furthermore, the configurations of Embodiments 1 to 7 may be combined as appropriate. In addition, the following configurations are also within the scope of the technical concept of this disclosure.

[0133] (Note 1) A drive unit drives an optical element so that the illumination light scans the field of view of a region extending in one direction within the sample in that direction, A control unit controls the drive unit to synchronize the scanning of the illumination light with the integration period of a TDI sensor that receives light from the field of view illuminated by the illumination light. A lighting device equipped with this. (Note 2) The illumination light includes EUV light generated from plasma produced by irradiating a target with laser light. The optical component includes a mirror that reflects the laser light toward the target, The drive unit drives the optical member so that the laser light scans the target in a predetermined direction, thereby causing the illumination light to scan in one direction within the field of view. The lighting device described in Appendix 1. (Note 3) The drive unit drives the optical member such that the relationship between the position and time of the laser beam on the target includes a triangular wave. The lighting device described in Appendix 2. (Note 4) The drive unit drives the optical member such that the relationship between the position and time of the laser beam on the target includes a wave obtained by superimposing at least one of a triangular wave, a sine wave, and a square wave. The lighting device described in Appendix 2. (Note 5) The spot of illumination light in the aforementioned field of view is circular. The lighting device described in Appendix 1. (Note 6) The spot of illumination light in the field of view is elliptical in shape, with its major axis extending in a direction perpendicular to the other direction. The lighting device described in Appendix 1. (Note 7) The optical component includes at least one of the following: a mirror that reflects the illumination light onto the sample, a beam shifter that shifts the illumination position of the illumination light, and an acoustic-optical element that shifts the illumination position of the illumination light. The drive unit drives the optical member so that the illumination light scans in one direction within the field of view. The lighting device described in Appendix 1. (Note 8) A drive unit drives an optical element so that the illumination light scans the field of view of a region extending in one direction within the sample in that direction, A control unit controls the drive unit so that the illumination light scans more times than a predetermined number of scans in one integration cycle of the TDI sensor that receives light from the field of view illuminated by the illumination light, A lighting device equipped with this. (Note 9) The steps include driving an optical member so that the illumination light scans the field of view of a region extending in one direction within the sample in that direction, The steps include synchronizing the scanning of the illumination light with the integration period of a TDI sensor that receives light from the field of view illuminated by the illumination light, A lighting method equipped with [a specific feature / feature]. (Note 10) The illumination light includes EUV light generated from plasma produced by irradiating a target with laser light. The optical component includes a mirror that reflects the laser light toward the target, In the step of driving the optical member, The optical member is driven so that the laser beam scans the target in a predetermined direction, thereby causing the illumination light to scan in one direction within the field of view. The lighting method described in Appendix 9. (Note 11) In the step of driving the optical member, The optical member is driven such that the relationship between the position and time of the laser beam on the target includes a triangular wave. The lighting method described in Appendix 10. (Note 12) In the step of driving the optical member, The optical member is driven such that the relationship between the position and time of the laser beam on the target includes a wave obtained by superimposing at least one of a triangular wave, a sine wave, and a square wave. The lighting method described in Appendix 10. (Note 13) The spot of illumination light in the aforementioned field of view is circular. The lighting method described in Appendix 9. (Note 14) The spot of illumination light in the field of view is elliptical in shape, with its major axis extending in a direction perpendicular to the other direction. The lighting method described in Appendix 9. (Note 15) The optical component includes at least one of the following: a mirror that reflects the illumination light onto the sample, a beam shifter that shifts the illumination position of the illumination light, and an acoustic-optical element that shifts the illumination position of the illumination light. In the step of driving the optical member, The optical member is driven so that the illumination light scans in one direction within the field of view. The lighting method described in Appendix 9. (Note 16) The steps include driving an optical member so that the illumination light scans the field of view of a region extending in one direction within the sample in that direction, The steps include: causing the illumination light to scan more times than a predetermined number of scans in one integration cycle of a TDI sensor that receives light from the field of view illuminated by the illumination light; A lighting method equipped with [a specific feature / feature]. (Note 17) The system further includes a light source control unit that changes the intensity of the illumination light in synchronization with the integration period of the TDI sensor. A lighting device as described in any one of the items 1 to 8 of the appendix. (Note 18) The method further includes the step of changing the intensity of the illumination light in synchronization with the integration period of the TDI sensor. The lighting method described in any one of the appendices 9 to 16.

[0134] Furthermore, the following points may be considered. For example, when using pulsed IR laser light, it is necessary to optimize the relationship between the repetition frequency of the laser light and the scan frequency. When the number of scans is small, such as only a few (corresponding to Embodiment 1, for example), the repetition frequency of the laser light needs to be sufficiently high relative to the scan frequency. This is because, since it is not continuous emission, a low repetition frequency will cause the discrete emission of the laser light to result in non-uniformity in the intensity profile. For example, in the worst case, if only one pulse is emitted under the condition that only one scan occurs during integration, the profile will be the same as if no scan had occurred.

[0135] On the other hand, when the number of scans exceeds several tens (for example, corresponding to Embodiment 3), the repetition frequency of the laser beam and the scan frequency can be made approximately the same by performing the following synchronization operation. By synchronizing the two and slightly shifting the repetition frequency of the laser beam from the scan frequency, uniform illumination of the surface can be achieved. Furthermore, if the repetition frequency of the laser beam is sufficiently higher than the scan frequency, the laser beam frequencies do not need to be synchronized.

[0136] Furthermore, some or all of the processing of the control unit 630 of the lighting device 600 described above may be executed by a computer program. The program described above includes a set of instructions (or software code) for causing the computer to perform one or more of the functions described in the embodiments when loaded into a computer. The program may be stored in a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disc (DVD), Blu-ray® disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrical, optical, acoustic or other forms of propagating signals.

[0137] Furthermore, the following lighting program, which causes a computer to execute the lighting method of this embodiment, is also included in the technical concept of this embodiment.

[0138] The optical element is driven so that the illumination light scans the field of view of a region extending in one direction within the sample in that direction. The scanning of the illumination light is synchronized with the integration period of a TDI sensor that receives light from the field of view illuminated by the illumination light. A lighting program that causes a computer to perform a specific action.

[0139] The optical element is driven so that the illumination light scans the field of view of a region extending in one direction within the sample in that direction. In one integration cycle of the TDI sensor that receives light from the field of view illuminated by the illumination light, the illumination light is scanned more times than a predetermined number of scans. A lighting program that causes a computer to perform a specific action. [Explanation of symbols]

[0140] 1, 2 Inspection equipment 100 light sources 111 Container 112 Target 113 Bottom 114 Cylindrical section 115 Base 116 Inner surface 117 Groove 118 Heater 119 Debris Shield 120 Collector's Mirrors 121 Opening 127 Plasma 200 Illumination optical system 210 Ellipsoidal mirror 220 Ellipsoidal mirror 230 Recessed Mirror 300 detection optical system 310 Perforated concave mirror 311 holes 320 Convex mirror 330 plane mirror 340 concave mirror 410 detectors 411 detection surface 420 Image Processing Unit 500 samples 510 Top surface 511 Field of view 520 stages 530 Drive unit 600, 600a, 600b, 600c lighting equipment 610 Optical components 610a Beam Shifter 610b AOM 611 Focusing lens 620 Drive Unit 630 Control Unit 631 Processing Unit 632 Communications Department 633 Storage section 634 Interface section 700 Light source control unit LE EUV light L1 illumination light L2 reflected light LR laser light LS excitation laser R rotation axis

Claims

1. A drive unit that drives an optical member such that the detection surface of the TDI sensor is a field of view on a sample for detecting light, and within the field of view extending in one direction on the sample, the illumination light illuminating the sample has a moving component that scans in the one direction. A control unit controls the drive unit so that a scan having the unidirectional motion component by the illumination light is performed at a frequency that is an integer multiple of half the frequency at which the TDI sensor, which receives light from the field of view region, integrates the amount of light. Equipped with, The illumination light critically illuminates the sample. The TDI sensor comprises multiple image sensor arrays, each having multiple image sensors, and transfers information between image sensors belonging to the same image sensor array. The aforementioned one direction is the direction perpendicular to the image sensor array, The scan having the unidirectional moving component by the illumination light is performed such that, during the period in which the TDI sensor integrates the amount of light, the spot of illumination light moves across the field of view in at least one direction. Lighting device.

2. The illumination light includes EUV light generated from plasma produced by irradiating a target with laser light. The optical member defines the irradiation position of the laser light onto the target, The drive unit drives the optical member so that the laser light has a laser light movement component that scans the target in a predetermined direction, thereby giving the illumination light the movement component of the unidirectional scan. The lighting device according to claim 1.

3. The illumination light includes EUV light generated from plasma, The optical member defines the position on the optical path from the plasma generation position to the sample where the EUV light irradiates the sample. The lighting device according to claim 1.

4. The drive unit drives the optical member such that the relationship between the position and time of the laser beam on the target includes a triangular wave. The lighting device according to claim 2.

5. The drive unit drives the optical member such that the relationship between the position and time of the laser beam on the target includes a wave obtained by superimposing at least one of a triangular wave, a sine wave, and a square wave. The lighting device according to claim 2.

6. The spot of illumination light in the aforementioned field of view is circular. The lighting device according to claim 1.

7. The spot of illumination light in the field of view is elliptical in shape, with its major axis extending in a direction perpendicular to the other direction. The lighting device according to claim 1.

8. The optical component includes at least one of the following: a mirror that reflects the illumination light onto the sample, a beam shifter that shifts the illumination position of the illumination light, an acoustic-optic element that shifts the illumination position of the illumination light, and an electro-optic element. The lighting device according to claim 1.

9. The control unit controls the drive unit such that the number of reciprocating scans performed in one cycle of the TDI sensor's integration period, consisting of the moving component on one side in one direction of the illumination light and the moving component on the other side in the same direction, is an integer. The lighting device according to claim 1.

10. A step of driving an optical member such that the detection surface of the TDI sensor is a field of view on a sample for detecting light, and within the field of view extending in one direction on the sample, the illumination light illuminating the sample has a moving component that scans in the one direction. The steps include: causing the TDI sensor, which receives light from the field of view region, to perform a scan with the unidirectional moving component by the illumination light at a frequency that is an integer multiple of half the frequency at which the light intensity of the light is integrated; Equipped with, The illumination light critically illuminates the sample. The TDI sensor comprises multiple image sensor arrays, each having multiple image sensors, and transfers information between image sensors belonging to the same image sensor array. The aforementioned one direction is the direction perpendicular to the image sensor array, The scan having the unidirectional moving component by the illumination light is performed such that, during the period in which the TDI sensor integrates the amount of light, the spot of illumination light moves across the field of view in at least one direction. lighting method.

11. The illumination light includes EUV light generated from plasma produced by irradiating a target with laser light. The optical member defines the irradiation position of the laser light onto the target. In the step of driving the optical member, By driving the optical member so that the laser beam has a laser beam movement component that scans the target in a predetermined direction, the illumination light is given the movement component of the unidirectional scan. The lighting method according to claim 10.

12. The illumination light includes EUV light generated from plasma, The optical member defines the position on the optical path from the plasma generation position to the sample where the EUV light irradiates the sample. The lighting method according to claim 10.

13. In the step of driving the optical member, The optical member is driven such that the relationship between the position and time of the laser beam on the target includes a triangular wave. The lighting method according to claim 11.

14. In the step of driving the optical member, The optical member is driven such that the relationship between the position and time of the laser beam on the target includes a wave obtained by superimposing at least one of a triangular wave, a sine wave, and a square wave. The lighting method according to claim 11.

15. The spot of illumination light in the aforementioned field of view is circular. The lighting method according to claim 10.

16. The spot of illumination light in the field of view is elliptical in shape, with its major axis extending in a direction perpendicular to the other direction. The lighting method according to claim 10.

17. The optical component includes at least one of the following: a mirror that reflects the illumination light onto the sample, a beam shifter that shifts the illumination position of the illumination light, an acoustic-optic element that shifts the illumination position of the illumination light, and an electro-optic element. The lighting method according to claim 10.

18. In the step of driving the optical member, The number of round-trip scans performed in one cycle of the TDI sensor's integration period, consisting of the moving component on one side in one direction of the illumination light and the moving component on the other side in the same direction, is set to be an integer. The lighting method according to claim 10.

19. The TDI sensor further comprises a light source control unit that changes the intensity of the illumination light at a frequency that is an integer multiple of half the frequency at which the light intensity is integrated. A lighting device according to any one of claims 1 to 9.

20. The TDI sensor further comprises the step of changing the intensity of the illumination light at a frequency that is an integer multiple of half the frequency at which it integrates the amount of light. The lighting method according to any one of claims 10 to 18.

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