Optical device and method for controlling the optical device

Abstract

This invention provides an optical device and a control method for the optical device that enable high-throughput imaging under conditions where the focal position of the illumination light is different. [Solution] Line sensors 41-43 detect reflected light L21-L22. The optical system 20 focuses illumination light L11-L13 at different optical distances relative to positions P1-P3 of the sample S, and focuses the reflected light L21-L22 from positions P1-P3 onto line sensors 41-43, which are associated with positions P1-P3, respectively. The stage 30 changes the relative position between the sample S and the optical system 20 so that reflected light from the same area of ​​the sample S is incident on each of the line sensors 41-43.

Description

[Technical Field]

[0001] This disclosure relates to optical devices and methods for controlling optical devices, and more particularly to optical devices used with samples and methods for controlling optical devices. [Background technology]

[0002] To image and inspect samples such as photomasks and semiconductor wafers, it is common practice to acquire images of the samples using, for example, a confocal optical system. When imaging with a confocal optical system, a method is known for acquiring multiple images focused at different heights for samples that have a structure in the height direction (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-215546 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, changing the focal point of the illumination light relative to the sample requires time for altering the relative position of the sample and the optical system, as well as controlling the objective lens. Therefore, there is a trade-off between performing imaging while finely changing the focal point in the height direction and the throughput of the imaging process.

[0005] However, as the structures to be observed in samples become smaller, there is a need to establish a method that can achieve imaging with high throughput while finely changing the focal point in the height direction. [Means for solving the problem]

[0006] The optical apparatus according to this disclosure comprises: a plurality of light detection means for detecting incident light; an optical system for irradiating the sample with illumination light so as to focus it at a plurality of focusing positions spaced apart in a first direction parallel to the main surface of the sample and a second direction normal to the main surface, and for focusing secondary rays from the plurality of focusing positions onto the plurality of light detection means associated with each of the plurality of focusing positions; and a driving means for changing the relative position between the sample and the optical system so that the secondary rays from the same region on the main surface of the sample are incident on each of the plurality of light detection means. [Effects of the Invention]

[0007] This disclosure provides an optical device and a control method for the optical device that enable imaging under conditions with different focal positions of illumination light with high throughput. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically shows the configuration of the optical device according to Embodiment 1. [Figure 2] This figure shows the configuration of the main parts of the optical device according to Embodiment 1. [Figure 3] This diagram schematically shows an example of a detector configuration. [Figure 4] This figure shows an overview of imaging a specific location of the sample at the first timing. [Figure 5] This figure shows an overview of imaging a specific location of the sample at the second timing. [Figure 6] This figure shows an overview of imaging at a specific location of the sample at the third timing. [Figure 7] This figure schematically shows the configuration of the optical device according to Embodiment 2. [Figure 8] This figure shows the configuration of the main parts of the optical device according to Embodiment 2. [Figure 9] This figure shows an overview of imaging a specific location of the sample at the first timing. [Figure 10]It is a diagram schematically showing an overview of imaging of a specific position of a sample at a second timing. [Figure 11] It is a diagram schematically showing an overview of imaging of a specific position of a sample at a third timing. [Figure 12] It is a diagram schematically showing the configuration of an optical device according to Embodiment 3. [Figure 13] It is a diagram showing the configuration of a main part of the optical device according to Embodiment 3. [Figure 14] It is a diagram schematically showing the configuration of an optical device according to Embodiment 4. [Figure 15] It is a diagram schematically showing the configuration of an optical device according to Embodiment 5. [Figure 16] It is a diagram schematically showing the configuration of an optical device according to Embodiment 6. [Figure 17] It is a diagram showing an example of setting a plurality of different focal positions in an optical device. [Figure 18] It is a graph schematically showing the relationship between the luminance of a plurality of images acquired at different focal positions for a specific position of a sample and the focal positions. [Figure 19] It is a diagram schematically showing a change in focal position when detecting the height position of a specific position of a sample by combining driving of a stage in the X-axis direction and driving in the Z-axis direction. [Figure 20] It is a flowchart of operations of an optical device according to Embodiment 7. [Figure 21] It is a flowchart of operations of the optical device when determining which of a first condition and a second condition is satisfied. [Figure 22] It is a diagram schematically showing a scanning path in Embodiment 8. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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.

[0010] Embodiment 1 An optical device according to Embodiment 1 will now be described. The optical device according to this embodiment is configured as an optical device incorporated into a wafer inspection device used in a semiconductor manufacturing process, for example. Figure 1 is a schematic diagram showing the configuration of the optical device according to Embodiment 1. As shown in Figure 1, the optical device 1 has a light source unit 10, an optical system 20, a stage 30, a detector 40, and a processing unit 50. Hereinafter, the optical device 1 will be described as having a confocal optical system.

[0011] Here, for the sake of explaining the optical device 1, we introduce an XYZ Cartesian coordinate system. The X-axis is a horizontal axis extending to the right of the plane of the figure, and the direction in which the X-axis extends is called the X-axis direction. The Y-axis is a normal axis extending towards the back of the plane of the figure, and the direction in which the Y-axis extends is called the Y-axis direction. The Z-axis is a vertical axis extending upwards of the plane of the figure, and the direction in which the Z-axis extends is called the Z-axis direction. For example, the +Z-axis direction is called upward, and the -Z-axis direction is called downward. Note that upward and downward are for the sake of explanation and do not indicate the actual orientation of the optical device 1. In this embodiment, the main surface of the stage 30 that holds the sample S is the XY plane, which is parallel to the X-axis and Y-axis directions. Therefore, the normal direction perpendicular to the XY plane, which is the main surface of the stage 30, is the Z-axis direction.

[0012] Furthermore, in the following, the direction parallel to the main surface of sample S will also be referred to as the first direction. The direction normal to the main surface of sample S will also be referred to as the second direction.

[0013] The light source unit 10, the optical system 20, and the detector 40 constitute an imaging unit 100 that irradiates a sample S held on the stage 30 with illumination light L1 and images the reflected light L2 with the detector 40. In this embodiment, the imaging unit 100 is positioned such that its central axis is tilted by a predetermined angle θ with respect to the Z-axis direction, which is the normal direction of the stage 30, i.e., the normal direction of the main surface of the sample S. Figure 1 shows an example in which the central axis of the imaging unit 100 is tilted by an angle θ clockwise with respect to the Z-axis direction. The extension direction of the central axis of the imaging unit 100, which is tilted by an angle θ clockwise with respect to the Z-axis direction, is the central axis direction D A This is referred to as the central axis D, parallel to the plane of the paper in the diagram. A The direction perpendicular to the plane of the paper and tilted at an angle θ clockwise with respect to the X-axis is the radial direction D of the imaging unit 100. R Let's assume that.

[0014] The light source unit 10 emits illumination light L1 into the optical system 20. The light source unit 10 has a light source 11 and a light source slit 12. The light source 11 may be a lamp light source, an LED (Light Emitting Diode) light source, or a laser light source. The illumination light L1 emitted from the light source 11 is incident on the light source slit 12. The illumination light L1 may be, for example, visible light, ultraviolet light, or EUV (Extreme Ultraviolet) light.

[0015] The light source slit 12 is positioned as an element for converting illumination light L1 into illumination light from a point light source. The light source slit 12 is positioned radially D R A flat plate member having a main surface with the normal direction being the Y-axis direction has multiple slits with the Y-axis direction as the longitudinal direction and the central axis direction D A They are arranged along the line. Illumination light L1 enters the optical system 20 after passing through multiple slits in the light source slit 12.

[0016] The optical system 20 consists of a beam splitter 21, a relay lens 22, and an objective lens 23, and constitutes an imaging optical system that irradiates the sample S held on the stage 30 with illumination light L1 that has passed through the light source slit 12, and images the reflected light L2 from the sample S onto the detector 40. The beam splitter 21 is, for example, a half mirror, and reflects about half of the illumination light L1 toward the relay lens 22. The relay lens 22 emits the illumination light L1, which is diffused light that has passed through the light source slit 12, toward the objective lens 23.

[0017] The objective lens 23 has its central axis aligned with the central axis D of the imaging unit 100. A It is positioned to follow the curve. The objective lens 23 focuses the illumination light L1 onto the sample S.

[0018] Sample S is, for example, a bare wafer, a pre-processing wafer after polishing a bare wafer, a semi-finished wafer in a semiconductor process where a device pattern has been formed on the wafer, a mask blank, or a photomask on which a fine pattern has been formed on the upper surface of the mask blank. A pattern S2 may be formed on sample S as shown in Figure 1. The pattern S2 is formed, for example, by a layer of opaque material laminated on a flat plate member S1 that is transparent to illumination light L1.

[0019] The sample S is held on the upper surface of the holding portion 31 of the stage 30, with its thickness direction aligned with the Z-axis. The stage 30 is a three-dimensional drive stage equipped with a drive mechanism 32 capable of driving the holding portion 31 along the X-axis, Y-axis, and Z-axis directions. The control unit 52, located in the processing unit 50, controls the drive mechanism 32 to drive the holding portion 31 along the X-axis, Y-axis, and Z-axis directions, respectively. It is assumed that the amount of drive in the Z-axis direction, which is the thickness direction of the sample S, is smaller than the amount of drive in the X-axis and Y-axis directions, which are parallel to the plane of the sample S. Therefore, it is desirable that the drive speed in the X-axis and Y-axis directions is faster than the drive speed in the Z-axis direction. In the following, the stage 30 will also be referred to as the drive unit or drive means. The stage 30 may be driven by the drive mechanism 32 to rotate around the Z-axis, Y-axis, and Z-axis, respectively. This may allow the inclination between the normal direction of the main surface of the sample S and the axis of the optical system to be changed.

[0020] The reflected light L2 generated when the illumination light L1 illuminates the sample S is focused by the objective lens 23 and then incident on the beam splitter 21 via the relay lens 22.

[0021] In the following, reflected light L2 from sample S will also be referred to as secondary light produced when sample S is illuminated by illumination light L1. However, secondary light is not limited to reflected light. Secondary light may be various types of light, such as reflected light, scattered light, fluorescence, or transmitted light, produced when sample S is illuminated by illumination light L1.

[0022] The beam splitter 21 transmits approximately half of the reflected light L2. The reflected light L2 that has passed through the beam splitter 21 is incident on the detector 40. As a result, the reflected light L2 is focused onto the detection surface of the detector 40.

[0023] The detector 40 acquires an image of the sample S by detecting the reflected light L2 focused by the optical system 20. The detector 40 may be a camera with various imaging principles applicable to TDI cameras such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor.

[0024] In the optical device 1, the detector 40 and the processing unit 50 constitute a camera that captures an image of the sample S. The processing unit 50 is implemented using hardware resources such as a computer. The processing unit 50 has an image processing unit 51 and a control unit 52. The detector 40 and the processing unit 50 may be configured as a TDI (Time Delay Integration) camera or the like, as needed.

[0025] The image processing unit 51 acquires an image of the sample S by processing the detection signal DET, which indicates the detection result from the detector 40. The control unit 52 can drive the stage 30 in a desired direction and speed by providing a control signal CON1 to the drive mechanism 32. This allows the relative position between the sample S and the optical system 20 to be changed along the X, Y, and Z axes, respectively. Furthermore, the control unit 52 can control the imaging process in the image processing unit 51 by providing a control signal CON2 to the image processing unit 51. This allows the control unit 52 to cause the image processing unit 51 to perform imaging when the stage 30 moves to a desired position. As a result, the operation of the stage 30 and the timing of the imaging process in the image processing unit 51 can be suitably synchronized.

[0026] Next, the paths of illumination light and reflected light in the optical device 1 will be described in more detail. Fig. 2 is a diagram showing the configuration of a main part of the optical device according to the first embodiment. The following description focuses on illumination lights L11 to L13 included in illumination light L1 and reflected light from these illumination lights. Illumination lights L11 to L13 included in the illumination light L1 from the light source 11 respectively pass through slits provided on the +Z side, the center, and the -Z side of the light source slit 12, and enter different positions of the beam splitter 21 as diffused light. The illumination lights L11 to L13 are reflected by the beam splitter 21, enter different positions of the relay lens 22, and are converted into parallel light.

[0027] Hereinafter, for convenience of description, in the members constituting the imaging unit 100, in the radial direction D R the negative side is referred to as the -X side, and in the radial direction D R the positive side is referred to as the +X side. The illumination light L12 travels substantially straight through the relay lens 22 and enters the center of the objective lens 23. The illumination light L11 and the illumination light L13 intersect after being emitted from the relay lens 22, and then enter the objective lens 23. Accordingly, the illumination light L11 emitted from the -X side of the relay lens 22 enters the +X side of the objective lens 23. The illumination light L13 emitted from the +X side of the relay lens 22 enters the -X side of the objective lens 23.

[0028] In the optical device 1, the central axis of the imaging unit 100 (that is, the central axis direction D A ) is inclined clockwise by an angle θ with respect to the Y-axis direction, which is the normal direction of the main surface of the sample S. Therefore, the optical axes of the illumination lights L11 to L13 are inclined clockwise by an angle θ with respect to the Z-axis direction. As a result, the focal positions where the illumination lights L11 to L13 are condensed are respectively at different separated positions in the X-axis direction (first direction) and the Z-axis direction (second direction). It should be noted that, for two adjacent condensing positions, the distance in the first direction (here, the X-axis direction) is preferably larger than the distance in the second direction (here, the Z-axis direction).

[0029] In this example, illumination light L12 incident on the center of the objective lens 23 is focused by the objective lens 23 to focus at position P2 on the upper surface of the sample S. In contrast, illumination light L11 and L13 incident on the objective lens 23 are focused along the central axis D along the optical axis. A In this case, the illumination light L11 is focused to the same position as the illumination light L11. However, as described above, the optical axes of the illumination light L11 to L13 are inclined with respect to the Z-axis direction. Therefore, the optical distance from the objective lens 23 to the position P1 of the sample S illuminated by the illumination light L11 is shorter than the optical distance from the objective lens 23 to the position P2 of the sample S. As a result, the focal point where the illumination light L11 is focused is shifted downward by ΔZ from the top surface of the sample S. On the other hand, the optical distance from the objective lens 23 to the position P3 of the sample S illuminated by the illumination light L13 is longer than the optical distance from the objective lens 23 to the position P2 of the sample S. As a result, the focal point where the illumination light L13 is focused is shifted upward by ΔZ from the top surface of the sample S.

[0030] Thus, in this configuration, the optical axes of the illumination light L11~L13 (central axis direction D) are relative to the main surface of the sample S. A By tilting the ), the focal position of the illumination light L11~L13 relative to the sample S in the Z-axis direction can be made different for each of the sample S positions P1~P3.

[0031] The reflected light L21-L23 generated by the illumination light L11-L13 incident on the sample S follows the reverse path of the illumination light L11-L13 and is incident on the beam splitter 21. The reflected light L21-L23 that has passed through the beam splitter 21 is incident on the detector 40.

[0032] The detector 40 has a central axis direction D A Multiple line sensors, with the Y-axis direction as the longitudinal direction, are positioned on a detection surface perpendicular to the radial direction D R They are arranged in the following direction. Figure 3 is a schematic diagram showing an example of the detector configuration. Here, on the detection surface of the detector 40, three line sensors 41 to 43 with the Y-axis direction as the longitudinal direction are arranged in the radial direction D R Let's explain the examples that are arranged in this way.

[0033] For the sake of the following explanation, in the detector 40, the three line sensors 41-43 with the Y-axis direction as the longitudinal direction are defined as the radial direction D R The example shown illustrates how they are arranged with a certain distance between them, but this is merely an example. In the detector, multiple line sensors other than the three whose longitudinal direction is the Y-axis are arranged radially D R They may be arranged in a specific manner. Furthermore, multiple line sensors may be arranged continuously without gaps, or they may be spaced apart.

[0034] The reflected light L21 is focused on the line sensor 41 located on the -X side of the detector 40. The reflected light L22 is focused on the line sensor 42 located in the center of the detector 40. The reflected light L23 is focused on the line sensor 43 located on the +X side of the detector 40. As a result, the detector 40 can detect the reflected light L21 to L23 from different positions P1 to P3 of the sample S using the line sensors 41 to 43, which are each associated with the reflected light L21 to L23. Each of the line sensors 41 to 43 outputs a detection signal DET indicating the detection result of the reflected light L21 to L23. That is, the image processing unit 51 receives the detection signal DET, which includes multiple signals indicating the detection results of the reflected light L21 to L23.

[0035] As explained above, in the optical device 1, the optical axes of the illumination rays L11 to L13 are tilted clockwise by an angle θ with respect to the Z-axis direction, which is the normal direction to the main surface of the sample S. This allows the depth position of the focal point of the illumination rays L11 to L13 incident on the sample S, which is the position in the Z-axis direction, to be different for each of the positions P1 to P3 of the sample S. In other words, the focal point of the illumination rays L11 to L13 can be positioned at different optical distances from the surface of the sample S, allowing for imaging of the sample S.

[0036] Therefore, with the optical device 1, in a single image taken by the detector 40, reflected light L21 to L23 corresponding to three illumination light L11 to L13 with different focal positions in the Z-axis direction, which is the height direction of the sample S, can be detected by line sensors 41 to 43, respectively.

[0037] Furthermore, in the optical device 1, the drive mechanism 32 drives the holding part 31 with the distance in the X-axis direction (first direction) of two adjacent focusing positions in the X-axis direction as the movement pitch, thereby eliminating the need to change the relative positional relationship (also referred to as relative position) between the sample S and the objective lens 23 in the Z-axis direction. This allows imaging to be performed by illuminating a specific, identical position on the sample S (also referred to as the same region on the principal plane of the sample S) with three illumination lights L11 to L13 that have different focal positions in the Z-axis direction, which is the height direction of the sample S. The specific, identical position on the sample S, or the same region on the principal plane of the sample S, may mean a region where the positions in the coordinate plane of the principal plane are equal, but the positions of the sample S in the perpendicular direction to the principal plane are different.

[0038] The following describes the operation of illuminating and imaging a region of the sample S at the same position on its main surface with illumination lights L11 to L13 focused at different positions. Figure 4 is a diagram illustrating the overview of imaging at a specific position of the sample at the first timing. In the first imaging, the specific position P of the sample S (a specific region on the main surface of the sample S) is assumed to be at the position where the illumination light L13 is incident. At this time, the reflected light L23 from position P corresponding to the illumination light L13 is detected by the line sensor 43.

[0039] Figure 5 shows an overview of imaging at a specific position of the sample at the second timing. In Figure 5, compared to Figure 4, the stage 30 is driven to move the sample S by a predetermined pitch in the X-axis direction, moving the position P of the sample S to the position where the illumination light L12 is incident. At this time, the reflected light L22 from position P corresponding to the illumination light L12 is detected by the line sensor 42.

[0040] Figure 6 shows an overview of imaging at a specific position of the sample at the third timing. In Figure 6, compared to Figure 5, the stage 30 is driven to move the sample S by a predetermined pitch in the X-axis direction, moving the position P of the sample S to the position where the illumination light L11 is incident. At this time, the reflected light L21 from position P corresponding to the illumination light L11 is detected by the line sensor 41.

[0041] Therefore, with the optical device 1, by moving the sample S in the X-axis direction at a predetermined pitch, the position P of the sample S can be sequentially illuminated with illumination lights L11 to L13 and repeatedly imaged. Based on the detection results of line sensors 41 to 43 for the position P of the sample S, multiple images of the sample S at different focal points can be acquired.

[0042] As mentioned above, it is desirable that the distance between two adjacent focusing positions in the first direction (in this case, the X-axis direction) is greater than the distance in the second direction (in this case, the Z-axis direction). In this case, between two consecutive imaging scans, the movement pitch of the same position on the main surface of the sample S along the first direction (in this case, the X-axis direction) in the same region will be greater than the distance between two adjacent focusing positions in the second direction (in this case, the Z-axis direction).

[0043] Furthermore, for example, if the detector 40 and the processing unit 50 are configured as a TDI camera, an image may be generated by combining images captured at different focal positions.

[0044] When observing the interior of a sample S, it is desirable that the change in focal position required to acquire multiple images at position P be sufficiently small. For example, if the depth of focus of the imaging unit at multiple focal positions is DF, it is desirable that the distance in the normal direction to the main surface of the sample S between two adjacent focal positions be less than or equal to the depth of focus DF. This allows for obtaining images at multiple focal positions that are closely spaced at position P.

[0045] Thus, with this configuration, images of multiple locations with different focal points on the sample can be acquired in a single imaging pass. Furthermore, by repeating the imaging while moving the sample, multiple images of a specific location on the sample at different focal points can be efficiently acquired. As a result, this configuration makes it possible to image a sample at multiple focal points with high throughput.

[0046] Embodiment 2 The optical device according to Embodiment 2 is a modified version of the optical device 1 according to Embodiment 1. Figure 7 is a schematic diagram showing the configuration of the optical device according to Embodiment 2. Figure 8 is a diagram showing the configuration of the main parts of the optical device according to Embodiment 2. The optical device 2 has a configuration in which the optical system 20 of the optical device 1 is replaced with an optical system 60.

[0047] The light source unit 10, the optical system 60, and the detector 40 constitute an imaging unit 200 that irradiates a sample S held on the stage 30 with illumination light L1 and detects the reflected light L2 with the detector 40. In this embodiment, the imaging unit 200 is positioned so that its central axis is not tilted with respect to the main surface of the sample S, but is aligned along the Z-axis direction.

[0048] In the light source slit 12 of the light source unit 10 in this configuration, a flat plate member having a main surface with the X-axis direction as the normal direction has multiple slits arranged along the Z-axis direction with the Y-axis direction as the longitudinal direction.

[0049] In the detector 40, the detection surface is a plane perpendicular to the Z-axis direction, and line sensors 41 to 43, whose longitudinal direction is the Y-axis direction, are arranged on the detection surface in the X-axis direction.

[0050] Optical system 60 has a configuration in which the objective lens 23 of optical system 20 is replaced with an objective lens 63. The objective lens 63 is positioned so that its central axis is tilted by a predetermined angle θ clockwise with respect to the Z-axis direction, which is the normal direction of the sample S. The objective lens 63 focuses the illumination light L1 onto the sample S held on the stage 30. The other configurations of optical system 60 are the same as those of optical system 20, so redundant explanations are omitted.

[0051] In optical device 2, illumination light L12 travels roughly in a straight line through relay lens 22 and enters the center of objective lens 63. Illumination light L11 and illumination light L13 intersect after being emitted from relay lens 22 before entering objective lens 63. As a result, illumination light L11 emitted from the -X side of relay lens 22 enters the +X side of objective lens 63. Illumination light L13 emitted from the +X side of relay lens 22 enters the -X side of objective lens 63.

[0052] In the optical apparatus 2, the objective lens 63 is positioned at an angle θ in a clockwise direction with respect to the principal surface of the sample S, with respect to an axis along the Y-axis. The optical axes of the illumination light L11 to L13 incident on the sample S are tilted at an angle θ in a clockwise direction with respect to the Z-axis perpendicular to the principal surface of the sample S.

[0053] In this example, illumination light L12, incident on the center of the objective lens 23, is focused by the objective lens 23 to focus at position P2 on the upper surface of the sample S. Illumination light L11, incident on the +X side of the objective lens 23, is incident on position P1 of the sample S via a shorter optical distance from the objective lens 23 compared to illumination light L12, so its focal point is shifted downward by ΔZ from the upper surface of the sample S. Illumination light L13, incident on the -X side of the objective lens 23, is incident on position P3 of the sample S via a longer optical distance from the objective lens 23 compared to illumination light L12, so its focal point is shifted upward by ΔZ from the upper surface of the sample S. As a result, illumination light L11 to L13 are focused at different positions along the Z-axis direction, which is the thickness direction of the sample S, similar to Embodiment 1.

[0054] The following describes the operation of illuminating the same specific position of the sample S with illumination light L11 to L13 focused at different positions and then imaging it. Figure 9 is a diagram showing an overview of imaging at a specific position of the sample at the first timing. In the first imaging, the specific position P of the sample S is assumed to be at the position where the illumination light L13 is incident. At this time, the reflected light L23 from position P corresponding to the illumination light L13 is detected by the line sensor 43, as in Embodiment 1.

[0055] Figure 10 shows an overview of imaging at a specific position of the sample at the second timing. In Figure 10, compared to Figure 9, the stage 30 is driven to move the sample S by a predetermined pitch in the X-axis direction, moving the position P of the sample S to the position where the illumination light L12 is incident. At this time, the reflected light L22 from position P corresponding to the illumination light L12 is detected by the line sensor 42, as in Embodiment 1.

[0056] Figure 11 shows an overview of imaging at a specific position of the sample at the third timing. In Figure 11, compared to Figure 10, the stage 30 is driven to move the sample S by a predetermined pitch in the X-axis direction, moving the position P of the sample S to the position where the illumination light L11 is incident. At this time, the reflected light L21 from position P corresponding to the illumination light L11 is detected by the line sensor 41, as in Embodiment 1.

[0057] Therefore, with the optical device 1, similar to Embodiment 1, the position P of the sample S can be illuminated sequentially with illumination lights L11 to L13 and repeatedly imaged. Based on the detection results of line sensors 41 to 43 for the position P of the sample S, multiple images of the sample S at different focal positions can be acquired.

[0058] As described above, in optical device 2, similar to optical device 1 in Embodiment 1, the optical distances between the objective lens 63 and positions P1 to P3 are all different. As a result, with optical device 2, it is not necessary to change the relative positional relationship in the Z-axis direction between the sample S and the optical system 60, and the sample S can be imaged in the same way as with optical device 1 in Embodiment 1.

[0059] Embodiment 3 The optical device according to Embodiment 3 is a modified version of the optical device 1 according to Embodiment 1. Figure 12 is a schematic diagram showing the configuration of the optical device according to Embodiment 3. Figure 13 is a diagram showing the configuration of the main parts of the optical device according to Embodiment 3. In the optical device 3, the relative positional relationship between the imaging unit 100, the sample S and the stage 30 is the same as that of the optical device 1 according to Embodiment 1.

[0060] On the other hand, in this embodiment, the imaging unit 100 is positioned so that its central axis is aligned with the Z-axis direction. In contrast, the normal direction of the main surface of the stage 30 and the sample S is inclined by an angle θ counterclockwise with respect to the Z-axis direction, which is the optical axis of the illumination light L11 to L13. That is, the holding portion 31 of the stage 30 is positioned so that its upper surface is inclined by an angle θ counterclockwise with respect to the optical axis of the illumination light L1.

[0061] Hereinafter, the axis obtained by rotating the X-axis by an angle θ in the counterclockwise direction will be referred to as the Ax-axis. The axis obtained by rotating the Z-axis by an angle θ in the counterclockwise direction will be referred to as the Az-axis direction and the Az-axis direction, respectively. Therefore, in this embodiment, the normal direction of the stage 30 and the sample S is the Az-axis direction. The drive mechanism 32 drives the holding part 31 along the Ax-axis direction, the Y-axis direction, and the Az-axis direction, respectively.

[0062] In this configuration, the central axis of the objective lens 23 is aligned with the Z-axis direction. Therefore, the focal positions of the illumination beams L11 to L13 are the same in the Z-axis direction (Z=0).

[0063] On the other hand, the sample S is tilted at an angle θ counterclockwise around an axis along the Y-axis with respect to a plane whose normal direction is the optical axes of the illumination light L11~L13. Therefore, the optical distance from the illumination light L11 emitted from the objective lens 23 to the position P1 of the sample S is shorter than the optical distance from the illumination light L12 emitted from the objective lens 23 to the position P2 of the sample S. The optical distance from the illumination light L13 emitted from the objective lens 23 to the position P3 of the sample S is longer than the optical distance from the illumination light L12 emitted from the objective lens 23 to the position P2 of the sample S.

[0064] Therefore, in optical device 3, similar to optical device 1 according to Embodiment 1, the optical distances between the objective lens 23 and positions P1 to P3 are all different. As a result, with optical device 3, it is not necessary to change the relative positional relationship in the Z-axis direction between the sample S and the optical system 20, and the sample S can be imaged in the same way as with optical device 1 according to Embodiment 1.

[0065] Furthermore, by driving the holding unit 31 along the Ax axis direction with the drive mechanism 32, the sample S can be moved along the Ax axis direction at a predetermined pitch. This makes it possible to repeatedly image the position P of the sample S, similar to Embodiment 1.

[0066] Embodiment 4 The optical device according to Embodiment 4 is a modified example of the optical device according to the above-described embodiment. Figure 14 is a schematic diagram showing the configuration of the optical device according to Embodiment 4. The imaging unit 400 of the optical device 4 has an optical system 20 similar to that of the imaging unit 100 of the optical device 3. Furthermore, the imaging unit 400 has a configuration in which the light source slit 12 of the imaging unit 100 is replaced with a light source slit 13, and the arrangement of the detector 40 is changed.

[0067] The light source slit 13 is arranged such that the positions of the slits passing through the illumination light L11 to L13 are different in the X-axis direction. In this example, the position of the slit passing through the illumination light L12 is the same as that of the light source slit 12 in the above-described embodiment. Therefore, the paths of the illumination light L12 and the reflected light L22 are the same as those of the optical device 3 in embodiment 3.

[0068] The slit through which the illumination light L11 passes is positioned closer to the beam splitter 21 than the slit through which the illumination light L12 passes, i.e., shifted to the +X side. Therefore, the illumination light L11 focuses downwards, i.e., on the -Z side, compared to the illumination light L12. The reflected light L21 generated when the illumination light L11 is incident on the sample S is incident on the line sensor 41 via the optical system 20.

[0069] The slit through which the illumination light L13 passes is positioned further from the beam splitter 21 than the slit through which the illumination light L12 passes, i.e., shifted to the -X side. Therefore, the illumination light L13 focuses upward, i.e., on the +Z side, compared to the illumination light L12. The reflected light L23 generated when the illumination light L13 is incident on the sample S is incident on the line sensor 43 via the optical system 20.

[0070] Therefore, in the optical device 4, similar to Embodiment 1, illumination light L11 to L13 incident on the sample S at positions P1 to P3 can be focused at different positions along the Z-axis.

[0071] In this configuration, as described above, the optical distances between each of the slits of the light source slit 13, which converts the illumination light L11 to L13 into a point light source, and the sample S are different. Therefore, the positions of the focal points in the Z-axis direction of the reflected light L21 to L23 incident on the detector 40 from the sample S via the optical system 20 are also different. In this embodiment, the focal points of the reflected light L21 to L23 are sequentially shifted in the +Z direction in accordance with the focal points of the illumination light L11 to L13.

[0072] In order to suitably detect the reflected light L21 to L23, the detector 40 is positioned such that the detection surface is tilted by an angle θ in the counterclockwise direction about an axis along the Y-axis with respect to a plane perpendicular to the optical axis of the reflected light L21 to L23.

[0073] Therefore, the optical distance between the sample S at position P1 and the line sensor 41 is shorter than the optical distance between the sample S at position P2 and the line sensor 42. The optical distance between the sample S at position P3 and the line sensor 43 is longer than the optical distance between the sample S at position P2 and the line sensor 42.

[0074] Therefore, in the optical device 4, similar to the optical device according to the above-described embodiment, the focal points of the illumination light L11 to L13 can be positioned at different optical distances from the sample S to image the sample S. As a result, with the optical device 4, similar to the optical device according to the above-described embodiment, it is not necessary to change the relative positional relationship in the Z-axis direction between the sample S and the optical system 20 to image the sample S.

[0075] Furthermore, by driving the holding portion 31 in the X-axis direction with the drive mechanism 32, the sample S can be moved in the X-axis direction at a predetermined pitch. This makes it possible to repeatedly image the position P of the sample S, similar to the optical device according to the above-described embodiment.

[0076] Embodiment 5 The optical device according to Embodiment 5 is a modified version of the optical device 4 according to Embodiment 4, and the detector configuration is different. Figure 15 is a schematic diagram showing the configuration of the optical device according to Embodiment 5. The imaging unit 500 of the optical device 5 is a modified version in which the detector 40 in the imaging unit 400 of the optical device 4 according to Embodiment 4 is replaced with a detector 70.

[0077] In the detector 70, line sensors 41 to 43 are arranged so that their detection surfaces are perpendicular to the optical axes of reflected light L21 to L23. Furthermore, line sensors 41 to 43 are positioned at different locations in the Z-axis direction such that the optical distances between the sample positions P1 to P3 and the line sensors 41 to 43 are different.

[0078] In this example, line sensor 41 is positioned closer to the relay lens 22 in the Z-axis direction than line sensor 42. Line sensor 43 is positioned further from the relay lens 22 in the Z-axis direction than line sensor 42.

[0079] As a result, the optical device 5 can also detect reflected light L21 to L23 using line sensors 41 to 43, similar to the optical device 4 in Embodiment 4. Consequently, the optical device 5 can image the sample S, similar to the optical device 4 in Embodiment 4.

[0080] Embodiment 6 The optical apparatus according to Embodiment 6 is a modified version of the optical apparatus according to the above-described embodiment, and by changing the configuration of the optical system, the optical distance of the path through which the illumination light L11 to L13 that irradiates the sample S passes is changed.

[0081] Figure 16 is a schematic diagram showing the configuration of the optical device according to Embodiment 6. The imaging unit 600 of the optical device 6 in Figure 16 has a configuration in which the optical system 20 of the imaging unit 100 in the optical device 3 according to Embodiment 3 is replaced with an optical system 80. In addition, in the optical device 6, the stage 30 and the sample S are arranged such that the normal direction of the main surface is the Z-axis direction, that is, the main surface is perpendicular to the Z-axis direction.

[0082] The optical system 80 has a configuration in which a relay lens 84, an optical path length conversion unit 85, and a relay lens 86 are added to the optical system 20.

[0083] The relay lens 84, the optical path length conversion unit 85, and the relay lens 86 are inserted between the relay lens 22 and the objective lens 23 in this order.

[0084] Illumination light L12 travels roughly in a straight line through relay lens 22 and enters the center of relay lens 84. Illumination light L11 and illumination light L13 intersect after being emitted from relay lens 22 before entering relay lens 84. As a result, illumination light L11 emitted from the -X side of relay lens 22 enters the +X side of relay lens 84. Illumination light L13 emitted from the +X side of relay lens 22 enters the -X side of relay lens 84.

[0085] Illumination light L11 to L13 are focused by the relay lens 84 and then incident on the optical path length conversion section 85, which is inserted before the focal point. The optical path length conversion section 85 is a step wedge optical component with parallel plates of different thicknesses in the Z-axis direction connected in the X-axis direction. In this example, the thickness of the optical path length conversion section 85 is thinner at the position through which illumination light L11 passes than at the position through which illumination light L12 passes. Therefore, the optical path length through which illumination light L11 passes in the optical path length conversion section 85 is shorter than the optical path length through which illumination light L12 passes. Also, the thickness of the optical path length conversion section 85 is thicker at the position through which illumination light L13 passes than at the position through which illumination light L12 passes. Therefore, the optical path length through which illumination light L13 passes in the optical path length conversion section 85 is longer than the optical path length through which illumination light L12 passes.

[0086] The illumination light L11 to L13 that have passed through the optical path length conversion unit 85 are focused once, then diffused, and incident on the relay lens 86. Illumination light L12 travels almost in a straight line through the relay lens 86 and incident on the center of the objective lens 23. Illumination light L11 and illumination light L13 intersect after being emitted from the relay lens 86 before incident on the objective lens 23. As a result, illumination light L11 emitted from the +X side of the relay lens 86 is incident on the -X side of the objective lens 23. Illumination light L13 emitted from the -X side of the relay lens 86 is incident on the +X side of the objective lens 23. Therefore, in the optical device 5, compared to the embodiment described above, the positional relationship in the X-axis direction of illumination light L11 and L13 incident on the objective lens 23 is reversed.

[0087] Illumination light L12 incident on the center of the objective lens 23 is focused by the objective lens 23 to focus on position P2 on the upper surface of the sample S. Illumination light L11 incident on the -X side of the objective lens 23 enters the sample S through a shorter optical path than illumination light L12, so its focal position is ΔZ lower compared to illumination light L12. Illumination light L13 incident on the +X side of the objective lens 23 enters the sample S through a longer optical path than illumination light L12, so its focal position is ΔZ higher compared to illumination light L12.

[0088] The reflected light L21-L23 generated by the illumination light L11-L13 incident on the sample S follows the reverse path of the illumination light L11-L13 and is incident on the beam splitter 21. The reflected light L21-L23 that has passed through the beam splitter 21 is incident on the detector 40.

[0089] In the detector 40, as in the third embodiment, reflected light L21 to L23 is collected by line sensors 41 to 43, respectively. As a result, the detector 40 can detect reflected light L21 to L23 from different positions on the sample S using line sensors 41 to 43, respectively.

[0090] Therefore, in the optical device 6, similar to the optical device 3 according to Embodiment 3, for example, the focal points of the illumination light L11 to L13 can be positioned at different optical distances from the sample S to image the sample S. As a result, with the optical device 6, similar to the optical device according to the above-described embodiment, it is not necessary to change the relative positional relationship in the Z-axis direction between the sample S and the optical system to image the sample S.

[0091] Furthermore, by driving the holding unit 31 in the X-axis direction with the drive mechanism 32, the sample S can be moved in the X-axis direction at a predetermined pitch. This makes it possible to repeatedly image the position P of the sample S, similar to the embodiment described above.

[0092] Embodiment 7 In the above-described embodiment, multiple images at different focal positions were acquired by the detector 40 for an arbitrary position P. In contrast, with the optical device according to the above-described embodiment, it is also possible to detect the height position of position P in the sample S, i.e., the position in the Z-axis direction, using the multiple images acquired for an arbitrary position P. The process for detecting the height position of position P in the sample S will be described below.

[0093] Figure 17 shows an example of setting multiple different focal positions in an optical device. Figure 17 shows an example in which five different focal positions F1 to F5 are set at an arbitrary position P on a sample S. The focal positions F1 to F5 are indicated by circles with a focal depth DF, and the center of the circle is the focal position. Two adjacent focal positions among F1 to F5 are separated along the Z-axis by a focal pitch FP.

[0094] Since the position of position P in the Z-axis direction (also referred to as the height position of position P on the surface) is unknown in advance, it is desirable that the range of change in focal position FR for acquiring multiple images of position P be sufficiently large. For example, in order to adequately follow the surface irregularities of the sample S, it is desirable that the range of change in focal position FR be greater than the thickness T of the sample S. More specifically, it is preferable that the range of change in focal position FR be greater than or equal to the thickness T of the sample S plus twice the depth of focus DF. In this case, it is also preferable that the range of change in focal position FR be greater by the depth of focus DF on the lower side in the thickness direction of the sample S, and greater by the depth of focus DF on the upper side in the thickness direction of the sample S.

[0095] As described above, when multiple images are acquired at an arbitrary position P of the sample S at multiple focal positions, the brightness of the images changes according to the focal position. Figure 18 is a schematic graph showing the relationship between the brightness of multiple images acquired at different focal positions for position P and the focal position. Figure 18 shows the brightness of the images when images are acquired at five different focal positions F1 to F5. In this case, the relative positions of the sample S and the optical system 20 when images are acquired at five different focal positions F1 to F5 may differ at a predetermined pitch in the direction of the principal surface of the sample S. As shown in Figure 18, the brightness of the image has an upward convex profile that changes according to the focal position. For example, in the processing unit 50, an approximation curve C can be obtained as shown by the dashed line in Figure 18 by interpolating the five brightness points using a known method. In general, the brightness of an image captured by an optical device is maximum when it is in focus on the surface of the sample S, so the brightness is at its maximum value B. MAX The focal position corresponding to the peak PK of the approximation curve C is the position of position P in the sample S in the Z-axis direction (depending on the embodiment, this may be interpreted as the position of position P in the Az direction; hereafter, for simplicity, it will be referred to as the position of position P in the sample S in the Z-axis direction). In Figure 18, the position near the -Z side of the focal position F2 is the height position of the surface of the sample S in the Z-axis direction.

[0096] Thus, according to this embodiment, the processing unit 50 can detect the position P in the sample S in the Z-axis direction.

[0097] To improve the detection accuracy of the Z-axis position of position P, it is desirable that the focal pitch FP within the range of focal position change FR be sufficiently small. On the other hand, if the processing unit 50 can detect the Z-axis position of position P with the desired accuracy using the approximation curve C, the number of imaging cycles at position P may be reduced by increasing the focal pitch FP. This reduces the time required to detect the Z-axis position of position P. Furthermore, if the Z-axis position of position P can be detected with the desired accuracy even with a larger focal pitch FP, the angle between the normal direction of the main surface of the sample S and the principal optical axis of the objective lens 23 may be increased. This reduces the time required to detect the Z-axis position of position P for a sample S with a large thickness T. The angle (tilt angle) between the normal direction of the main surface of the sample S and the principal optical axis of the objective lens 23 may be changeable by a drive unit (not shown). The drive unit (not shown) may be configured as a drive means integrated into the drive mechanism 32, or it may be a separate drive means from the drive mechanism 32.

[0098] If the amount of change in focal position that can be achieved by the optical device is insufficient, imaging performed while scanning the stage 30 in the X-axis direction (hereinafter referred to as the scanning operation) may be combined with driving the stage 30 in the Z-axis direction. In other words, after acquiring multiple images with different focal positions for position P in one scanning operation, the stage 30 may be driven in the Z-axis direction to change the position of the sample S in the Z-axis direction. Then, by performing the scanning operation again, multiple images with different focal positions for position P may be acquired. In this case, it is desirable to drive the stage 30 so that the range in which the focal positions F1 to F5 are located in the previous scanning operation and the range in which the focal positions F1 to F5 are located in the next scanning operation do not overlap in the Z-axis direction.

[0099] Figure 19 schematically shows the change in focal position when detecting the height position of the surface at position P in the Z-axis direction by combining the X-axis and Z-axis direction drives of the stage 30. In this example, the range of focal position change is set to twice the thickness T of the sample S. In this case, if the range of focal position change cannot be covered by scanning the stage 30 only in the X-axis direction, the range of focal position change can be covered by combining it with driving the stage 30 in the Z-axis direction. In Figure 19, imaging is performed at five focal positions F1 to F5 within the +Z side 1 / 3 of the focal position change range FR in one scan operation. Then, after moving the stage 30 by FR / 3 in the +Z-axis direction, imaging is performed at the same five focal positions F1 to F5. After that, the stage 30 is moved another FR / 3 in the +Z-axis direction, and imaging is performed at the same five focal positions F1 to F5. As a result, images of position P at 15 different focal positions can be obtained within the focal position change range FR.

[0100] Next, the operation of the optical device in the case of Figure 19 will be described. Figure 20 is a flowchart of the operation of the optical device according to Embodiment 7.

[0101] Step ST1 The control unit 52 moves the stage 30 to the starting position for height measurement.

[0102] Step ST2 The control unit 52 causes the stage 30 to perform a scan operation in the X-axis direction. As a result, the image processing unit 51 acquires multiple images of the sample S at focal points F1 to F5 at position P.

[0103] Step ST3 The control unit 52 determines whether the scan operation has been completed for the entire range of the preset focal position change range FR.

[0104] Step ST4 If the scan operation is not completed across the entire range of the focal position change FR, the control unit 52 moves the stage 30 to ΔZF Move only to the +Z side. Then, return the process to step ST2.

[0105] Step ST5 If the scanning operation is completed over the entire range of the focal position change FR, the control unit 52 detects the height position in the Z-axis direction of the surface of the sample S at position P based on the acquired image.

[0106] As described above, this operation allows for the acquisition of multiple images at different focal positions around the sample S at a desired focal pitch, regardless of the sample S's thickness. Based on these multiple images, the height position of the surface of the sample S at position P in the Z-axis direction can be detected.

[0107] In Embodiments 1 to 6, the first condition is defined as the situation in which an instruction is given to the optical device to perform a first operation, which involves acquiring multiple images at different focal positions at the same location on the main surface of the sample S. In Embodiment 7, the second condition is defined as the situation in which an instruction is given to the optical device to perform a second operation, which involves detecting the height position in the Z-axis direction of the surface of the sample S at position P. The control unit 52 may determine whether the first or second condition is met and control whether to have the optical device perform the first or second operation based on the determination result. In this case, the control unit 52 may determine that the first condition is met, for example, based on the first condition being specified by the user. The control unit 52 may determine that the second condition is met, for example, based on the second condition being specified by the user.

[0108] In this case, under the first condition, the control unit 52 may control the inclination of the optical system axis with respect to the normal direction of the main surface of the sample S using the driving means, thereby setting the distance in the Z-axis direction between adjacent focusing positions to be within the depth of focus DF. Alternatively, under the second condition, the control unit 52 may control the inclination of the optical system axis with respect to the normal direction of the main surface of the sample S using the driving means, thereby setting the distance in the Z-axis direction between adjacent focusing positions to be further away than the depth of focus DF.

[0109] Furthermore, the optical device according to this embodiment may automatically perform an operation according to the condition after determining whether the first or second condition is met. Figure 21 is a flowchart of the operation of the optical device when determining whether the first or second condition is met.

[0110] Step ST11 The control unit 52 moves the stage 30 to the starting position.

[0111] Step ST12 The control unit 52 determines whether the first condition or the second condition is met. The user of the optical device may provide the control unit 52 with a signal or information specifying which of the first and second conditions is met in advance. Alternatively, the information specifying which of the first and second conditions is met may be stored in any storage device located inside or outside the optical device. In this case, the control unit 52 may read the information specifying which of the first and second conditions is met from the storage device in step ST12 and make the determination.

[0112] Step ST13 Depending on the determination result in step ST12, the control unit 52 controls the driving means to adjust the tilt angle to a predetermined angle corresponding to the first or second condition. If the first condition is met, the control unit 52 may adjust the tilt angle so that the distance in the Z-axis direction between adjacent focusing positions is within the depth of focus DF. If the second condition is met, the control unit 52 may set the tilt angle so that the distance in the Z-axis direction between adjacent focusing positions is greater than the depth of focus DF.

[0113] Step ST14 The control unit 52 causes the stage 30 to perform a scan operation in the X-axis direction. As a result, the image processing unit 51 acquires multiple images of the sample S at position P with different focal points in the Z-direction.

[0114] Step ST15 The control unit 52 determines whether the scan operation has been completed for the entire range of the preset focal position change range FR.

[0115] Step ST16 If the scan operation is not completed across the entire range of the focal position change FR, the control unit 52 moves the stage 30 to ΔZ F Move only to the +Z side. Then, return the process to step ST14.

[0116] Step ST17 The control unit 52 performs information processing based on the acquired images depending on whether the first or second condition is met. If the first condition is met, the control unit 52 acquires multiple images at different focal positions for the same location on the main surface of the sample S based on the acquired images. If the second condition is met, the control unit 52 detects the height position in the Z-axis direction of the surface of the sample S at position P based on the acquired images. The control unit 52 may also acquire multiple images at different focal positions for the same location on the main surface of the sample S based on the acquired images. Furthermore, the control unit 52 may detect the height position in the Z-axis direction of the surface of the sample S at position P based on the acquired images.

[0117] By controlling the operation of the optical device through the above procedure, the optical device can automatically perform operations that match the conditions that are met, depending on whether the first or second condition is met. This allows the optical device to automatically and efficiently perform operations according to the specified conditions simply by the user specifying the desired conditions.

[0118] Embodiment 8 This embodiment describes a modified method for scanning the sample S by driving the stage 30. Figure 22 is a schematic diagram showing the scan path in Embodiment 8. In Figure 22, two-dimensional polar coordinates using the radial radius R and angular angle φ are used instead of the X and Y axes of the Cartesian coordinate system.

[0119] In this example, the holding portion 31 of the stage 30 is configured as a circular parallel plate member with the Z-axis direction as the normal direction. The sample S is a circular member, and may be, for example, a semiconductor wafer on which a circuit pattern is formed.

[0120] In this configuration, by rotating the holding unit 31 around its central axis and driving it in the Z-axis direction, an image of the sample S can be acquired while scanning the sample S in a helical manner. For example, with the illumination light L1 emitted from the objective lens 23 illuminating the area near the outer circumference of the sample S, a helical scan of the sample S can be performed by rotating the holding unit 31 around its central axis and driving it in the Z-axis direction.

[0121] In this case, imaging can be smoothly and repeatedly performed on a specific location of the sample S by shifting the focal position of the illumination light, as shown in the cross-sectional view V1 of Figure 22. This allows for the easy acquisition of a 3D image by combining images with different depths of focus, as shown in the overhead view V2 of Figure 22.

[0122] It goes without saying that the helical scan according to Embodiment 8 can be applied to any of the optical devices according to Embodiments 1 to 5 described above.

[0123] Other embodiments Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be made as can be understood by those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0124] For the sake of explanation, the diagram shows typical optical elements included in the optical system, but the optical system may also include various other optical elements not shown, such as lenses, optical scanners, mirrors, filters, and beam splitters. Furthermore, for example, the optical system may be a confocal optical system.

[0125] Furthermore, to drive the sample S relative to the optical system, the stage may be moved relative to the optical system, or the sample S may be fixed and the optical device may be driven relative to the sample S.

[0126] The illumination light L11 to L13 may be broadband light of a predetermined width. In this case, the detector may detect light from multiple bands included in the predetermined broadband width. Alternatively, the illumination light L11 to L13 may be narrowband light of a specific band.

[0127] The above description was based on three illumination beams L11-L13, three focusing positions P1-P3, and three line sensors 41-43, but this is merely an example. If necessary, multiple illumination beams other than the three may be focused at multiple positions other than the three on the sample S, and these reflected lights may be detected by multiple line sensors other than the three.

[0128] Furthermore, although the above-described embodiment described an optical device using a bright-field illumination method, the illumination method of the optical device is not limited to this.

[0129] The above-described configuration of the optical apparatus is merely illustrative, and other configurations are possible as long as illumination light L1 emitted from the light source unit 10 irradiates the sample S and secondary light rays from the sample S are detected by the detector. For example, although the optical apparatus according to the above embodiment was described as being configured as a refractive optical system, it may be configured as a refractive reflective optical system or a reflective optical system as needed.

[0130] Although the detector has been described as having multiple line sensors, the multiple images of position P and the multiple images used to detect the position of position P in the height direction may be images output from all of the multiple line sensors provided in the detector, or images output from some of them, as needed.

[0131] In Embodiment 7, the case where the main surface of the stage 30, i.e., the main surface of the sample S, is parallel to the XY plane was described, but this is merely an example. Even when the main surface of the stage 30, i.e., the main surface of the sample S, is inclined with respect to the XY plane, as in Embodiment 3, the height position in the direction normal to the surface of the sample S at position P may be detected by combining a scanning operation in the Ax axis direction with driving the stage 30 in the Az axis direction.

[0132] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be made as can be understood by those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0133] Each drawing is merely illustrative to illustrate one or more embodiments. Each drawing may be associated with one or more other embodiments rather than with only one specific embodiment. As those skilled in the art will understand, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings, for example, to create embodiments not explicitly shown or described. Not all features or steps shown in any one drawing to illustrate an exemplary embodiment are necessarily required, and some features or steps may be omitted. The order of steps shown in any of the drawings may be changed as appropriate. [Explanation of Symbols]

[0134] 1~6 Optical device 10 Light source section 11 Light source 12, 13 Light source slits 20, 60, 80 optics 21 Beam Splitter 22, 84, 86 Relay Lens 23, 63 objective lens 85 Optical path length conversion section 30 stages 31 Holding part 32 Drive mechanism 40, 70 detectors 41-43 Line Sensor 50 Processing Unit 51 Image Processing Unit 52 Control Unit 100, 200, 400, 500, 600 Imaging Unit S sample S1 Flat plate member S2 Pattern CON1, CON2 control signals DET detection signal L1, L11~L13 Illumination Light L2, L21~L23 reflected light

Claims

1. Multiple light detection means for detecting incident light, An optical system that irradiates the sample with illumination light so as to focus it at a plurality of focusing positions spaced apart in a first direction parallel to the main surface of the sample and a second direction normal to the main surface, and focuses the secondary rays from the plurality of focusing positions onto a plurality of photodetectors associated with each of the plurality of focusing positions, The system includes a driving means for changing the relative position between the sample and the optical system such that secondary rays from the same region on the main surface of the sample are incident on each of the plurality of photodetectors. optical equipment.

2. Image processing means that acquires multiple signals based on the detection results of the secondary light rays by the multiple light detection means, The system includes a control means for controlling the image processing means to acquire the plurality of signals based on the detection results of the secondary rays by the plurality of light detection means, while controlling the driving means so that the relative position changes in the first direction. The optical apparatus according to claim 1.

3. The image processing means acquires, based on the acquired signal, a plurality of images corresponding to a plurality of secondary rays from different focusing positions in the second direction, which are detected by different light detection means for regions with the same position on the main plane. The optical apparatus according to claim 2.

4. In the second direction, the distance between two adjacent focusing positions among different focusing positions is within the depth of focus of the optical system. The optical apparatus according to claim 3.

5. Based on the acquired signal, the image processing means detects the position in the second direction of the surface of the region where the principal plane is located, based on the intensity of multiple secondary rays from different focusing positions in the second direction, which are detected by different light detection means for the same region on the principal plane. The optical apparatus according to claim 2.

6. The image processing means detects the position in the second direction of the surface of the region where the position on the principal plane is the same, based on the peak of an approximation curve that shows the relationship between the focusing position in the second direction and the intensity of the secondary rays, which is generated by interpolating the intensities of the plurality of secondary rays. The optical apparatus according to claim 5.

7. In the second direction, the distance between two adjacent focusing positions among different focusing positions is greater than the depth of focus of the optical system. The optical apparatus according to claim 5 or 6.

8. The control means is When the specified first condition is met, While controlling the driving means to change the relative position in the first direction, the image processing means is controlled to acquire the plurality of signals based on the detection results of the secondary rays by the plurality of light detection means, and based on the acquired signals, to acquire the plurality of images corresponding to the plurality of secondary rays from different focusing positions in the second direction, which are detected by different light detection means in the same region on the main surface. When the specified second condition is met, The driving means is controlled to change the relative position in the first direction, and the plurality of signals are acquired based on the detection results of the secondary rays by the plurality of photodetectors, and the image processing means is controlled based on the acquired signals to detect the position in the second direction of the surface of the region where the principal surface is located, based on the intensities of the plurality of secondary rays from different focusing positions in the second direction, which are detected by different photodetectors in the same region on the principal surface. The optical apparatus according to claim 2.

9. The driving means is capable of changing the inclination angle, which is the angle between the second direction and the direction of the principal optical axis of the objective lens of the optical system. The control means is When the predetermined first condition is met, the driving means is controlled such that the distance between the plurality of light-gathering positions becomes the inclination angle such that the distance between them is within the depth of focus of the optical system in the second direction. When the predetermined second condition is met, the driving means is controlled such that the distance between two condensing positions included in at least one set of two adjacent condensing positions from the plurality of condensing positions is such that the inclination angle in the second direction is greater than the depth of focus of the optical system. The optical apparatus according to claim 8.

10. The control means is The drive means is controlled so that the relative position changes in the second direction. The image processing means is controlled to acquire the plurality of signals based on the detection results of the secondary rays by the plurality of photodetectors, while controlling the driving means so that the relative position between the sample and the optical system in the first direction changes at each of the plurality of relative positions where the distance between the sample and the optical system in the second direction is different. The optical apparatus according to claim 2.

11. The control means controls the driving means to change the relative position in the first and second directions, and controls the image processing means to acquire the plurality of signals based on the detection results of the secondary light rays by the plurality of light detection means. The optical apparatus according to claim 2.

12. The driving means changes the relative position in the second direction, The amount of change in the relative position in the first direction per unit time is greater than the amount of change in the relative position in the second direction. The optical apparatus according to claim 2.

13. The optical system has an objective lens that focuses the illumination light, The principal optical axis of the objective lens is positioned at an inclination with respect to the first forward direction. The optical apparatus according to claim 1 or 2.

14. The system includes a light source that emits the illumination light into the optical system, The light source and the plurality of light detection means are fixed to the optical system. The driving means can change the inclination angle, which is the angle between the principal optical axis of the objective lens and the second direction, by driving the optical system. The relative positions of the light source, the optical system, and the plurality of light detection means remain constant regardless of the change in the tilt angle. The optical apparatus according to claim 13.

15. The optical system has an objective lens that focuses the illumination light, The illumination light focused through the objective lens toward the plurality of focusing positions of the sample is light that has passed through a plurality of slits, each positioned at a different optical distance from the objective lens. Each of the plurality of light detection means is arranged to receive the secondary light rays from the plurality of light-gathering positions in a focused state. The optical apparatus according to claim 1 or 2.

16. The plurality of light detection means are arranged in a predetermined direction perpendicular to the optical axis of the incident secondary light ray, The arrangement of the plurality of light detection means is inclined with respect to the optical axis of the secondary light ray, with respect to the direction perpendicular to the optical axis of the secondary light ray and the predetermined direction. The optical apparatus according to claim 15.

17. Each of the plurality of light detection means is arranged at a different position along the optical axis of the incident secondary light ray. The optical apparatus according to claim 15.

18. The optical system includes optical distance conversion means that causes the optical distance of the path through which each of the illumination light beams focused toward the plurality of focusing positions of the sample passes to differ. The optical apparatus according to claim 1 or 2.

19. The sample is scanned helically by the incident illumination light. The optical apparatus according to claim 1 or 2.

20. The illumination light is light with a predetermined bandwidth, The plurality of light detection means detect each of the plurality of light bands included in the predetermined width band. The optical apparatus according to claim 1 or 2.

21. The illumination light is light of a predetermined band, The plurality of light detection means detect light in the predetermined band. The optical apparatus according to claim 1 or 2.

22. The plurality of light-gathering positions of the sample are arranged in a direction perpendicular to or intersecting the optical axis of the incident illumination light. The plurality of light detection means are arranged in a direction corresponding to the plurality of light collection positions, Each of the aforementioned plurality of light detection means is configured as a line sensor in which a plurality of light-receiving elements are arranged in a direction orthogonal to the direction corresponding to the plurality of light-collecting positions. The optical apparatus according to claim 1 or 2.

23. The aforementioned light-gathering positions are three or more, and the system has three or more of the aforementioned light detection means. The optical apparatus according to claim 1 or 2.

24. A method for controlling an optical device according to claim 1 or 2, While controlling the driving means so that the relative position changes in the first direction, multiple signals are acquired based on the detection results of the secondary light rays by the multiple light detection means. A method for controlling optical devices.

25. Based on the acquired signal, multiple images are acquired corresponding to multiple secondary rays from different focusing positions in the second direction, which are detected by different light detection means for regions with the same position on the main surface. A method for controlling an optical device according to claim 24.

26. Based on the acquired signal, the position in the second direction of the surface of the region where the principal surface is located is detected based on the intensity of multiple secondary rays from different focusing positions in the second direction, which are detected by different light detection means for the same region on the principal surface. A method for controlling an optical device according to claim 24.

27. When the specified first condition is met, While controlling the driving means so that the relative position changes in the first direction, acquire the plurality of signals based on the detection results of the secondary rays by the plurality of photodetectors, and acquire the plurality of images based on the acquired signals, corresponding to the plurality of secondary rays from different focusing positions in the second direction, which are detected by different photodetectors in the same region on the main plane. When the specified second condition is met, While controlling the driving means so that the relative position changes in the first direction, acquire the plurality of signals based on the detection results of the secondary rays by the plurality of photodetectors, and based on the acquired signals, detect the position in the second direction of the surface of the region where the principal surface is located, based on the intensity of the plurality of secondary rays from different focusing positions in the second direction, which are detected by different photodetectors in the same region on the principal surface. A method for controlling an optical device according to claim 24.

28. The driving means is capable of changing the inclination angle, which is the angle between the second direction and the direction of the principal optical axis of the objective lens of the optical system. When the predetermined first condition is met, the driving means is controlled such that the distance between the plurality of light-gathering positions becomes the inclination angle such that the distance between them is within the depth of focus of the optical system in the second direction. When the predetermined second condition is met, the driving means is controlled such that the distance between two condensing positions included in at least one set of two adjacent condensing positions from the plurality of condensing positions is such that the inclination angle in the second direction is greater than the depth of focus of the optical system. A method for controlling an optical device according to claim 27.

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