Substrate evaluation method and substrate evaluation apparatus

Abstract

Provided is a technique for more appropriately inspecting an anisotropic object in a substrate using a laser light scattering method. For each measurement region on the surface of the substrate, respective scattered light is measured using an optical system located in a first direction and a second direction with respect to the measurement region to obtain first measurement data and second measurement data, and the first measurement data and the second measurement data are synthesized to generate synthesized data.

Description

Technical Field

[0001] This invention relates to a substrate evaluation method and apparatus using laser light scattering. Background Technology

[0002] During manufacturing or processing, foreign matter may sometimes adhere to the surface of semiconductor substrates, or defects may arise on the surface or inside. These foreign matter or defects can lead to the production of defective products, making substrate evaluation techniques indispensable. For example, in semiconductor devices manufactured using semiconductor substrates, the presence of foreign matter or defects can result in reduced device performance or device malfunction.

[0003] In substrate inspection using laser light scattering, the surface or internal condition of the substrate can be inspected by irradiating the substrate surface with a laser and measuring the scattered light. For comprehensive substrate inspection, the following method is generally used: scanning a laser across the two-dimensional surface of the substrate and measuring the scattered light generated in various areas of the substrate.

[0004] In substrate inspection using laser light scattering, the anisotropy of the inspected object affects the measurement data. To ensure thorough inspection of difficult-to-detect objects based on their anisotropy, Patent Document 1 describes the following surface condition inspection apparatus.

[0005] Patent Document 1 discloses a surface condition inspection device. In this device, a laser beam irradiated onto the surface of the flat substrate placed on the X-axis or Y-axis stage is scanned in either direction along the X-axis or Y-axis by a light-emitting system. Simultaneously, the device feeds at predetermined intervals along an axis orthogonal to the scanning direction and receives scattered light from the surface through a light-receiving system. The entire surface condition of the flat substrate is inspected based on a detection signal corresponding to the intensity of the received light. The device is characterized by comprising at least two light-emitting systems that emit light from different directions at predetermined incident angles relative to the substrate normal of the flat substrate on the surface side. A laser irradiates a surface; at least two light-receiving systems are disposed on the surface side and are respectively disposed opposite to the light-projection system at positions opposite to the light-projection system with reference to the laser irradiation point; a laser shaping unit shapes the laser so that the laser irradiation area on the surface of the flat substrate is rectangular; an irradiation area interval adjustment unit adjusts the interval between the rectangular laser irradiation areas to the projected length of the rectangle in the scanning direction or the non-overlapping length of the laser irradiation areas (i.e., non-overlapping length); a feed interval adjustment unit adjusts the specified interval of the feed in the axial direction to a length greater than or equal to the projected length or non-overlapping length, or an integer multiple of the projected length or non-overlapping length.

[0006] Existing technical documents

[0007] Patent documents Patent Document 1: Japanese Patent Application Publication No. 2015-075339 Summary of the Invention The problem to be solved by the present invention As a result of further research into the above-mentioned technology, the inventors have invented a method for substrate evaluation using laser light scattering that can improve the influence of substrate anisotropy on measurement and enable more appropriate evaluation. The problem to be solved by this invention is to provide a technique for more appropriately inspecting anisotropic objects in a substrate using laser light scattering.

[0008] Solution to the problem [1] A substrate evaluation method using laser light scattering, the substrate evaluation method comprising: In the measurement process, for each measurement area on the substrate surface, an optical system positioned in a first direction and a second direction with that measurement area as a reference is used to measure the scattered light of that area, thereby obtaining first measurement data and second measurement data; and The synthesis process combines the first measurement data and the second measurement data to generate synthesized data.

[0009] [2] According to the substrate evaluation method described in [1], the first direction and the second direction are different in the in-plane direction of the substrate.

[0010] [3] According to the substrate evaluation method described in [1] or [2], wherein the first direction and the second direction are orthogonal in their in-plane directions.

[0011] [4] The substrate evaluation method according to any one of [1] to [3], wherein the optical system includes a light-receiving optical system for receiving scattered light generated by the substrate. In the measurement process, the light-receiving optical system located in the first and second directions with the measurement area as a reference is used to measure the scattered light in each direction to obtain the first measurement data and the second measurement data.

[0012] [5] According to the evaluation method described in any one of [1] to [3], wherein the optical system includes a light-projecting optical system for irradiating the surface of the substrate with a laser. In the measurement process, the light-emitting optical system located in the first direction and the second direction with the measurement area as a reference is used to measure the scattered light in each direction to obtain the first measurement data and the second measurement data.

[0013] [6] The substrate evaluation method according to any one of [1] to [5], wherein the measurement step includes: measuring scattered light in a plurality of measurement regions of the substrate by scanning a laser on the surface of the substrate.

[0014] [7] According to the substrate evaluation method described in [6], the first direction and the second direction are set for the scanning direction of the scan.

[0015] [8] According to the substrate evaluation method described in [6] or [7], the measurement area is set such that its long side direction is inclined relative to the scanning direction of the scan.

[0016] [9] The substrate evaluation method according to any one of [1] to [8], wherein the measurement step includes: irradiating the surface of the substrate with a laser while rotating the substrate in an in-plane direction, and measuring the scattered light.

[0017]

[10] According to the substrate evaluation method described in [9], in the measurement process, the laser is irradiated onto the rotation track of the substrate by rotating the substrate in the in-plane direction. The in-plane directions of the first direction and the in-plane directions of the second direction are set relative to the rotational track at a first angle and a second angle.

[0018]

[11] The substrate evaluation method according to any one of [1] to

[10] , wherein the measurement step includes a first measurement step and a second measurement step. In the first and second measurement steps, the scattered light is measured by changing the direction of the measurement area relative to the fixed optical system, thereby obtaining the first measurement data and the second measurement data. In the synthesis process, the position information of the first measurement data and the second measurement data are aligned to generate the synthesized data.

[0019]

[12] According to the substrate evaluation method described in

[11] , in the first measurement step, first measurement data is obtained by scanning the laser while rotating the substrate in the in-plane direction and moving it in the first moving direction. In the second measurement process, the laser is scanned by rotating the substrate in the in-plane direction while moving it in a second movement direction different from the first movement direction, thereby obtaining the second measurement data.

[0020]

[13] According to the substrate evaluation method described in

[11] or

[12] , in the second measurement step, the measurement is started with the substrate rotated 90 degrees or 270 degrees from the start of the measurement in the first measurement step.

[0021]

[14] The substrate evaluation method according to any one of

[11] to

[14] , wherein the same optical system is used to measure the scattered light in the first measurement step and the second measurement step.

[0022]

[15] The substrate evaluation method according to any one of [1] to

[14] , wherein the measurement area is linear or rectangular.

[0023]

[16] A substrate evaluation apparatus using laser scattering method, the substrate evaluation apparatus comprising: A projection optical system for irradiating a substrate with laser light; Optical system for receiving scattered light; A mounting stage equipped with a three-axis drive unit for moving the plane of the substrate; and The control unit controls the stage to move toward a position that serves as a reference for the substrate, the position being the starting position for the first measurement and the second measurement, respectively.

[0024]

[17] According to the substrate evaluation apparatus of

[16] , the stage further includes a rotation drive unit for rotating the substrate. While the control unit rotates the stage via the rotary drive unit, it also controls the stage to move in different feed direction planes during the first and second measurements via the three-axis drive unit.

[0025]

[18] According to the substrate evaluation apparatus of

[16] or

[17] , the control unit performs position alignment on the position information of two measurement data obtained by the first measurement and the second measurement, and performs synthesis processing as composite data.

[0026] According to the invention described in [1], it is possible to generate synthetic data based on measurement data in two directions in a substrate, and to evaluate a substrate containing an anisotropic object with high precision.

[0027] According to the invention described in [2], it is possible to evaluate with high precision a substrate containing an anisotropic object in the in-plane direction.

[0028] According to the invention described in [3], measurement data with maximum information content can be obtained in both directions.

[0029] According to the invention described in [4], by receiving scattered light in two directions, it is possible to evaluate with high precision a substrate containing an anisotropic object.

[0030] According to the invention described in [5], by generating and measuring the scattered light in two directions, it is possible to evaluate with high precision a substrate containing an anisotropic object.

[0031] According to the invention described in [6], by scanning a laser, it is possible to measure the scattered light of each of multiple measurement areas and evaluate the scattered light of the entire surface of the substrate.

[0032] According to the invention described in [7], by setting two directions relative to the scanning direction for scanning, measurement data in two directions can be obtained on the entire surface of the substrate.

[0033] According to the invention described in [8], scanning time can be shortened by increasing the width of the measurement area.

[0034] According to the invention described in [9], scattered light can be measured at high speed over the entire surface of a substrate by means of rotation-based laser irradiation.

[0035] According to the invention described in

[10] , by setting two angles relative to the rotating track for measurement, measurement data in two directions can be obtained on the entire surface of the substrate.

[0036] According to the invention described in

[11] , measurement data can be obtained using an optical system by changing the orientation of the measurement area in two measurement processes.

[0037] According to the invention described in

[12] , measurement data in two directions can be obtained by rotating and moving the substrate.

[0038] According to the invention described in

[13] , by rotating the substrate at the start of the measurement, the measurement can be started while the substrate is in position alignment.

[0039] According to the invention described in

[14] , it is possible to suppress the differences in measurement data results caused by individual differences in the optical system.

[0040] According to the invention described in

[15] , by expanding the width of the measurement area, measurement can be performed in a short time.

[0041] According to the invention described in

[16] , when measuring two different measurement data, it is possible to control the stage to a position suitable for positioning.

[0042] According to the invention described in

[17] , in a rotary scan, by moving the stage in different feed directions, it is possible to obtain the results of measuring scattered light in different directions for a certain area of ​​the substrate.

[0043] According to the invention described in

[18] , by aligning the positions of two different measurement data, it is possible to generate synthetic data for evaluating a substrate containing an anisotropic object under inspection.

[0044] Effects of the present invention According to the present invention, a technique is provided for more appropriately inspecting anisotropic objects on a substrate using a laser light scattering method. Attached Figure Description

[0045] Figure 1 This is a schematic diagram illustrating the substrate evaluation method.

[0046] Figure 2 This is a structural diagram of the evaluation device.

[0047] Figure 3 This is a schematic diagram illustrating the measurement area according to one embodiment.

[0048] Figure 4 This is a schematic diagram illustrating the measurement area according to one embodiment.

[0049] Figure 5 This is a schematic diagram of the measurement process according to the first embodiment.

[0050] Figure 6 This is a schematic diagram illustrating the measurement process of Example 2.

[0051] Figure 7 This is a schematic diagram illustrating the measurement process of Example 3.

[0052] Figure 8 This is a diagram showing the direction of measurement as strong scattered light in each measurement process.

[0053] Figure 9 This is an explanatory diagram of the measurement process during scanning.

[0054] Figure 10 This is an explanatory diagram of the position alignment process.

[0055] Figure 11 This is an example of measurement data.

[0056] Figure 12 This is an example of synthetic data. Detailed Implementation

[0057] Hereinafter, preferred embodiments of the substrate evaluation method and substrate evaluation apparatus according to the present invention will be described in detail with reference to the accompanying drawings. The scope of the present invention is not limited to the embodiments shown in the drawings, and appropriate modifications can be made within the scope of the claims. Furthermore, in the following description of the embodiments and the accompanying drawings, the same reference numerals are used to refer to the same structures, and repeated descriptions are omitted.

[0058] Figure 1 This is a schematic diagram illustrating the substrate evaluation method of the present invention. Figure 1 As shown, the evaluation device 1 includes a light-emitting optical system 10 and a light-receiving optical system 20.

[0059] The light projection optical system 10 includes a laser output unit 11, a filter 12, a wavelength plate 13, and a focusing lens 14.

[0060] The light-receiving optical system 20 includes an objective lens 21, an imaging lens 22, a slit 23, and a light-receiving sensor 24. The light-receiving sensor 24 converts the intensity of the scattered light into an electrical signal as measurement data.

[0061] The substrate 100 can be a semiconductor wafer, a mask, a disk substrate, a liquid crystal substrate, a glass substrate, a transparent film, etc. In this embodiment, an example in which the substrate 100 is a semiconductor single crystal will be described in particular.

[0062] As the objects to be inspected, the substrate 100 includes surface inspection objects such as fine dust and other foreign matter attached to its surface, scratches / cracks, and surface irregularities, as well as internal inspection objects such as crystal defects and processing altered layers generated internally. The objects to be inspected generate scattered light when irradiated with a laser. Therefore, the evaluation device 1 can inspect the presence and extent of the inspection objects contained in the substrate 100 by measuring the scattered light.

[0063] In one example, substrate 100 may be a semiconductor material manufactured by a process including at least one of slicing, polishing, and grinding processes. A silicon (Si) substrate can be exemplified as a semiconductor substrate manufactured through these processes. In the aforementioned slicing, polishing, and grinding processes, a processing-modified layer that adversely affects device manufacturing may be introduced. In particular, recent studies have shown that processing-modified layers in compound semiconductor materials, which are classified as difficult-to-process materials, have adverse effects on devices.

[0064] Semiconductor single crystals can be made of materials such as silicon or compound semiconductors. Compound semiconductors include SiC, GaN, AlN, Ga2O3, sapphire, etc. In this embodiment, substrate 100 is described using single-crystal SiC as an example, but it is not limited to this.

[0065] The processing-modified layer includes lattice strain generated within the substrate due to processing. Strain that adversely affects semiconductor device manufacturing is located at depths of 1 μm to 20 μm, 1 μm to 10 μm, 1 μm to 8 μm, and 1 μm to 6 μm below the surface of the semiconductor substrate. The inspection area in the depth direction of the evaluation apparatus 1 is at least within the depth range of ~20 μm, ~10 μm, ~8 μm, and ~6 μm below the surface of the semiconductor substrate.

[0066] Strain refers to the deviation of the actual crystal lattice from an ideal lattice. Additionally, strain refers to the degree of its deviation. The evaluation method of this invention includes evaluating the strain, distribution, or uniformity of a substrate.

[0067] The projection optical system 10 illuminates the surface of the substrate 100 with incident light L1. The incident light L1 branches at the surface of the substrate 100 into reflected light L2, surface-scattered light L3, and transmitted light L4. In this embodiment, it is preferable that the reflected light L2 does not enter the light-receiving optical system 20. The surface-scattered light L3 can serve as the light path entering the light-receiving optical system 20. The transmitted light L4 can enter the interior of the substrate 100 and serve as the internal scattered light L5 entering the light-receiving optical system 20.

[0068] The light-receiving optical system 20 images the surface scattered light L3 and the internal scattered light L5 onto the light-receiving sensor 24 via the objective lens 21 and the imaging lens 22. The slit 23 selectively blocks the surface scattered light L3 and the internal scattered light L5 imaged on the light-receiving sensor 24. For example, the slit 23 can be configured to selectively block only the surface scattered light L3, only the internal scattered light L5, or both. Additionally, the slit 23 can be configured to selectively block internal scattered light L5 generated from the surface of the substrate 100 to any depth. The slit 23 can also be a variable slit capable of selecting the range of scattered light blocked.

[0069] Scattered light can include surface scattered light and internal scattered light. Surface scattered light can include scattered light originating from surface deposits, scattered light originating from surface irregularities, and scattered light originating from lattice defects. Internal scattered light can include scattered light originating from lattice defects and scattered light originating from internal strain.

[0070] Here, particularly in the case of measuring internal scattered light L5 originating from internal strain, it is preferable to suppress and / or detect scattered light other than that originating from internal strain, including scattered light originating from surface deposits, scattered light originating from surface irregularities, and scattered light originating from lattice defects, by appropriate methods. However, the scattered light may also include scattered light from outside the detection object within the range of intensity that allows for the determination of scattered light originating from internal strain.

[0071] When measuring the internally scattered light L5 originating from internal strain, by setting the surface of the substrate 100, which is planarized using a planarization process, surface scattered light L3 becomes difficult to generate, or the intensity of surface scattered light L3 decreases. As a result, the proportion of scattered light generated by the processed modified layer below the surface increases in the scattered light.

[0072] The surface of the semiconductor material substrate 100 is planarized by a planarization process such as chemical mechanical polishing. Quantitatively, the surface includes surfaces with an arithmetic mean roughness (Ra) of 0.5 nm or less. Preferably, the surface includes surfaces with an arithmetic mean roughness (Ra) of 0.4 nm or less, 0.3 nm or less, or 0.2 nm or less.

[0073] Figure 2 An example configuration diagram of the evaluation apparatus 1 is shown. The evaluation apparatus 1 includes a light-emitting optical system 10, a light-receiving optical system 20, a stage 30, a housing 40, and a control unit 50.

[0074] The projection optical system 10 irradiates a laser with a wavelength that is transparent to the substrate 100.

[0075] The incident angle θ of the laser based on the projection optical system 10 can be set to 0°≤θ<90°. The incident angle θ of the laser is not limited to perpendicular illumination of 0°=θ.

[0076] The incident angle θ of the laser preferably satisfies the following lower limits: 40°≤θ, 45°≤θ, or 50°≤θ, and the following upper limits: θ≤80°, θ≤75°, or θ≤70°.

[0077] When the incident angle θ is near the Brewster angle of the substrate 100 (Brewster angle ± approximately 10°), the P-polarized light penetrates deeper into the substrate 100, enabling the detection of the object to be inspected in a deeper part below the surface.

[0078] The projection optical system 10 can change the incident angle relative to the substrate 100. The incident angle of the projection optical system 10 is adjusted according to the angle control instruction of the control unit 50. When the laser is irradiated onto the measurement area 101 at different incident angles, the direction of the laser irradiation onto the object under inspection changes, thereby generating scattered light with different patterns. In one way, the measurement process can measure the intensity of the scattered light at a certain incident angle, and then change the incident angle to measure the intensity of the scattered light.

[0079] The laser output unit 11 is a laser source, and can be, for example, a gas laser such as a He-Ne laser, a semiconductor laser, or a solid-state laser such as a YAG laser. Furthermore, the laser output from the laser output unit 11 can be a second harmonic or third harmonic wavelength, obtained by converting its fundamental wavelength.

[0080] In this embodiment, when the substrate 100 is a semiconductor material, the wavelength of the laser preferably has a photon energy larger than the band gap. That is, the wavelength λ of the laser preferably satisfies the relationship "λ[nm]≤1239.8 / band gap[eV]".

[0081] Specifically, when measuring 4H-SiC, a wavelength of 380 nm or less is preferably set (λ[nm]≤1239.8 / 3.26[eV]). When measuring GaN, a wavelength of 365 nm or less is preferably set (λ[nm]≤1239.8 / 3.39[eV]).

[0082] The filter 12 is configured as either a wavelength filter that allows a specific wavelength of laser light to pass through or a wavelength filter that blocks a specific wavelength of laser light. The filter 12 can be a wavelength filter corresponding to the wavelength of the laser light used. The laser light becomes a single wavelength after passing through the filter 12. Laser light with a broad spectral width excites photoluminescence within the substrate 100, thus becoming a factor generating measurement noise. Furthermore, when using the laser light by converting the fundamental wavelength to the second harmonic, third harmonic, etc., other wavelengths not used in the measurement may become the main source of noise. In this embodiment, it is preferable that the laser light becomes a single wavelength by using the filter 12.

[0083] The wavelength plate 13 is equipped with a rotation mechanism, which can polarize the polarized light of the passing laser into either P-polarized or S-polarized light. The wavelength plate 13 can make the laser beam arbitrarily polarized according to the polarization instruction of the control unit 50. Since P-polarized and S-polarized laser light have different transmittances to the substrate 100, the wavelength plate 13 can be controlled according to the depth of the target object being inspected. The polarization state of the wavelength plate 13 is controlled according to the polarization control instruction of the control unit 50.

[0084] The condenser lens 14 is a lens that causes the laser to form a light spot on the surface of the substrate 100. The condenser lens 14 can shape the laser beam into any shape, such as circular, elliptical, rectangular, or linear. In this embodiment, the condenser lens 14 is a cylindrical lens. The cylindrical lens focuses parallel light into a rectangular or linear light spot. By tilting the long side of the rectangular or linear light spot relative to the scanning direction, a large area can be measured in a single scan, thereby achieving high-speed measurement.

[0085] The light-receiving optical system 20 measures the intensity of the scattered light generated by the substrate 100. The light-receiving optical system 20 is preferably configured at an angle that prevents reflected light from the surface of the substrate 100 from entering.

[0086] The measurement angle φ of the light-receiving optical system 20 can be set to 0°≤θ<90°, and is not limited to being set to 0°=φ and positioned at the top. The lower limit of the measurement angle φ of the light-receiving optical system 20 preferably satisfies 20°≤φ, 25°≤φ, or 30°≤φ, and the upper limit preferably satisfies φ≤70°, φ≤65°, or φ≤60°. The preferred measurement angle φ can suppress the incident light at a depth close to the surface of the substrate 100.

[0087] The light sensor 24 converts the intensity of the scattered light imaged through the slit 23 into an electrical signal. The light sensor 24 can be a photomultiplier tube or a photodiode, etc. The light sensor 24 can adjust its light sensitivity. For example, when the target is weakly scattered light (such as scattered light originating from internal strain), the light sensor 24 can be set to a high sensitivity.

[0088] The light-receiving optical system 20 preferably also includes a wavelength filter. The wavelength filter is configured to block light of wavelengths other than the wavelength of the laser emitted from the light-emitting optical system 10, in order to match the wavelength of the laser emitted from the light-emitting optical system 10. The wavelength filter blocks, for example, wavelengths that may become noise in the intensity measurement of scattered light, such as photoluminescence generated by the substrate 100.

[0089] A substrate 100 is disposed on a stage 30. The stage 30 includes a three-axis drive unit 31 and a rotation drive unit 32. The stage 30 is capable of moving in the XY directions, which are two-dimensional planes. Furthermore, the stage 30 is capable of rotating in the two-dimensional plane. The stage 30 can scan the substrate 100 using a laser by moving and / or rotating in the two-dimensional plane.

[0090] The stage 30 can move in both the horizontal and vertical directions by driving the three-axis drive unit 31 according to the movement command of the control unit 50. The stage 30 can also be rotated by driving the rotary drive unit 32 according to the rotation command of the control unit 50.

[0091] The movement and / or rotation of the control console 30 are based on the stage position information. The stage position information has an orthogonal coordinate system (X, Y, Z) and a rotational coordinate system (r, θ). The rotational coordinate system is represented by the feed position r relative to the radial direction of the substrate 100 and the rotation angle θ. The direction of the feed movement corresponds to the directions of the X and Y axes of the orthogonal coordinate system and is controlled by the drive of the three-axis drive unit 31. In the rotational coordinate system, by rotating the substrate 100 at the feed position r along the θ direction while simultaneously moving along the X or Y axis, movement along the r direction is effectively achieved. The feed position r obtained through the feed movement in the rotational coordinate system and the orthogonal coordinate position XY obtained through horizontal movement in the orthogonal coordinate system are distinguished from each other as position information.

[0092] Alternatively, the stage 30 can also be a structure that controls movement and / or rotation based on substrate position information. The substrate position information has an orthogonal coordinate system (X, Y, Z) and / or a rotational coordinate system (r, θ). The substrate position information represents the position on the substrate 100. In the evaluation of the substrate 100 according to this embodiment, the distribution of inspection objects included in the substrate 100 can be evaluated based on the measurement results of the scattered light intensity at each position on the substrate 100 represented by the substrate position information.

[0093] The housing 40 supports the light-emitting optical system 10 and the light-receiving optical system 20. Furthermore, the housing 40 can move in both the horizontal and vertical directions. The housing 40 can be configured to scan the laser by moving according to a movement instruction from the control unit 50.

[0094] In this embodiment, when the spot of the irradiation light is aligned with the position of the substrate 100, the stage 30 moves along the Z-axis, which is the vertical direction. Alternatively, the housing 40 may be configured to move in the vertical direction when the spot of the irradiation light is aligned with the surface of the substrate 100.

[0095] The control unit 50 is connected to the stage 30 and controls the movement and rotation of the stage 30. The control unit 50 acquires measurement data from the light-receiving optical system 20. The control unit 50 performs data synthesis processing on the measurement data.

[0096] The control unit 50 includes: a stage control unit 51 for controlling the stage 30; a signal processing unit 52 for processing signals as measurement data (measurement results) based on the intensity of the scattered light received by the light sensor 24; and a synthesis processing unit 53 for processing as synthesis data based on at least two or more measurement data.

[0097] The control unit 50 controls the measurement mode according to the object being inspected. The measurement mode can include modes corresponding to the depth, type, etc., of the object being inspected. The measurement modes include a surface measurement mode and an internal measurement mode corresponding to the depth of the object being inspected. The surface measurement mode is used to measure surface objects such as particles. The internal measurement mode is used to measure internal objects such as processed modified layers. In the surface measurement mode, the control unit 50 can output a control instruction to the wavelength plate 13 to make it S-polarized light; in the internal measurement mode, it can output a control instruction to the wavelength plate 13 to make it P-polarized light. Furthermore, in the internal measurement mode, the control unit 50 outputs a control instruction to the wavelength plate 13 to selectively switch between S-polarized light and P-polarized light according to the target depth. For example, in the internal measurement mode, when the target is the internal strain of the processed modified layer, the control unit 50 outputs a control instruction to the wavelength plate 13 to make it S-polarized light.

[0098] The control unit 50 is composed of one or more processors, such as a CPU (Central Processing Unit). The control unit 50 executes various processes, acting as the stage control unit 51, signal processing unit 52, and synthesis processing unit 53, by executing programs stored in a storage device. The control unit 50 can accept input operations via the operation interface of the evaluation device 1, and execute measurement and synthesis processes based on these input operations.

[0099] The evaluation method according to this embodiment includes a measurement step and a synthesis step. The measurement step is a step of irradiating the substrate 100 with a laser and measuring the intensity of the scattered light generated therefrom. In this embodiment, the measurement step includes a first measurement step and a second measurement step, and acquires measurement data from each step. The synthesis step is a step of generating synthesized data based on the individual measurement data.

[0100] <Measurement Process> The projection optical system 10 irradiates the measurement area of ​​the substrate 100 with laser light. The receiving optical system 20 measures the scattered light generated by the laser light irradiating the measurement area.

[0101] In this embodiment, a measurement area is defined in the substrate 100. The measurement area is defined by the laser irradiation area (spot) and / or the light-shielding area of ​​the slit 23. The measurement area on the substrate 100 is scanned by driving the stage 30, thereby measuring the scattered light on the entire surface of the substrate 100.

[0102] One method is to define the measurement area as any size and shape by deforming the shape of the spot of the irradiated light. Another method is to define the measurement area as any size and shape by using the slit 23 to limit the range of received scattered light.

[0103] In the measurement process of this embodiment, for each measurement area on the substrate surface, using that measurement area as a reference, the intensity of scattered light is measured using optical systems located in a first direction and a second direction, respectively, to obtain measurement data. The measurement data includes first measurement data from the first direction and second measurement data from the second direction. The measurement data may also include Nth measurement data from two or more directions (assuming N≥2).

[0104] Here, the optical system includes a light-emitting optical system 10 and / or a light-receiving optical system 20. The optical system viewed from the measurement area refers to at least one of the light-emitting optical system 10 and the light-receiving optical system 20. The first direction and the second direction are different directions in the in-plane direction of the XY plane of the substrate 100. When multiple measurement data are acquired in the measurement process, it is preferable that each measurement direction is at an equally spaced angle in the in-plane direction. Specifically, when two measurement data are acquired in the measurement process, it is preferable that the first direction and the second direction are orthogonal in the in-plane direction.

[0105] When the optical system is a projection optical system 10, in the measurement process, the projection optical system 10, which is located in the first direction and the second direction when viewed from the measurement area, is used to measure the scattered light generated respectively to obtain the first measurement data and the second measurement data. However, at this time, the direction of the receiving optical system 20 is not restricted.

[0106] When the optical system is a light-receiving optical system 20, the measurement process uses the light-receiving optical system 20 located in the first direction and the second direction when viewed from the measurement area to measure the intensity of the scattered light to obtain the first measurement data and the second measurement data, but at this time, the direction of the light-projecting optical system 10 is not restricted.

[0107] The measurement data obtained through the measurement process includes information on the intensity and location of the scattered light. The location information indicates the position where the intensity of the scattered light was measured, and can be either the substrate location information of the substrate 100 or the stage location information of the stage 30. When using the stage location information, a process is performed to convert the stage location information into substrate location information.

[0108] by Figure 3 , Figure 4 For example, using substrate 100 as a reference, spatial coordinates are defined to illustrate the measurement area. Figure 3 , Figure 4In the example, the in-plane direction of the substrate 100 is represented by XY coordinates, and the height direction (depth direction) is represented by Z coordinates. The measurement direction is defined as the direction of the light-emitting optical system 10 and / or the light-receiving optical system 20 relative to the measurement area. In other words, the measurement direction is the direction of the light-emitting optical system 10 and / or the light-receiving optical system 20 as viewed from the measurement area. In this embodiment, the measurement direction includes at least two different directions (a first direction and a second direction), thereby obtaining measurement data in two measurement directions.

[0109] Figure 3 (a) shows a view of the substrate 100 from above. The measurement area 101 is represented by the substrate position information in XY coordinates, with the substrate 100 as a reference. The intensity of scattered light across the entire surface of the substrate 100 is measured by scanning the measurement area 101 within the surface of the substrate 100. Figure 3 In (a), an example of a square measuring area 101 is shown, but it is not limited to this. The shape of the measuring area 101 can be adjusted by the condenser lens 14 and the slit 23.

[0110] The scattered light in region 101 is measured from different measurement directions (light-receiving directions). Figure 3 In (a), a light-receiving optical system 20A for detecting scattered light from the X direction and a light-receiving optical system 20B for detecting scattered light from the Y direction are illustrated, respectively. Thus, in the measurement process, scattered light from at least two directions is measured within a measurement area 101. Here, the light-receiving optical systems 20A and 20B can be either a method of sequentially measuring scattered light in both directions using the same optical system, or a method of simultaneously measuring scattered light in both directions using different optical systems.

[0111] Here, the angle of the incident light into the measurement area 101 is not limited. The projection optical system 10 can illuminate the measurement area 101 with the laser at an angle, or it can illuminate the measurement area 101 from directly above. The projection optical system 10 is preferably configured with an incident angle that increases the transmittance of the laser into the substrate 100. When the laser is P-polarized light, the incident angle is preferably Brewster's angle. By increasing the transmittance of the laser into the substrate 100, it is possible to measure the object being inspected located at a deeper position from the surface of the substrate 100.

[0112] Figure 3 (b) shows the view in the direction of arrow DA. Figure 3 (a) Measurement of the internal scattered light L5 at section AA'. The internal scattered light L5 is scattered in the tilted direction, with a horizontal component L51 in the X direction and a vertical component L52 in the Z direction. Figure 3In (b), the light-receiving optical system 20 is able to measure the scattered light, which depends on the horizontal component in the X direction and the vertical component in the Z direction.

[0113] Figure 3 (c) shows the view of DB in the direction of the arrow. Figure 3 (a) Measurement of the internal scattered light L5 at the BB' section. The internal scattered light L5 is scattered in the tilted direction, with a horizontal component L53 in the Y direction and a vertical component L54 in the Z direction. Figure 3 In (c), the light-receiving optical system 20 is able to measure the scattered light, which depends on the horizontal component in the Y direction and the vertical component in the Z direction.

[0114] exist Figure 3 (b) Figure 3 In (c), internal scattered light was used as an example for illustration, but even surface scattered light can be measured separately for the horizontal components of the scattered light that depend on the XY direction.

[0115] When the object being inspected exhibits anisotropy in the X and Y directions within the substrate 100, differences arise in the measurement data across the two directions. When the object being inspected is a long, thin scratch or defect, the in-plane anisotropy manifests as a difference in the measurement data across both directions. Furthermore, when the object being inspected is a fine defect or strain, the anisotropy occurs in-plane, resulting in differences in the measurement data across both directions. Additionally, when the object being inspected is subjected to strain, birefringence occurs in-plane, also resulting in differences in the measurement data across both directions. For example, when a scratch or defect is long and thin relative to the X direction, it can be understood that the intensity of scattered light in the X direction is less than the intensity of scattered light in the Y direction.

[0116] In reality, due to factors such as the direction or distribution of scratches or defects, birefringence, etc., the inspected object exhibits anisotropy within a plane. Therefore, for anisotropic inspected objects, in order to reduce the impact of anisotropy, it is preferable to refer to measurement data from multiple directions and adopt a comprehensive evaluation method.

[0117] Figure 4 (a) is a top view of the substrate 100, and Figure 3 Similarly, a measurement region 101 is defined on the substrate 100. Figure 4 In (a), the scattered light in measurement area 101 is generated by lasers from different measurement directions (irradiation directions). Figure 3 In (a), projection optical systems 10A and 10B, which illuminate laser light from the X direction and from the Y direction, are illustrated respectively. Figure 4In the measurement process, scattered light generated by laser irradiation from at least two directions is measured in a measurement area 101. Here, the projection optical systems 10A and 10B can be either a method of sequentially measuring scattered light from two directions using the same optical system, or a method of simultaneously measuring scattered light from two directions using different optical systems.

[0118] Here, the configuration of the light-receiving optical system 20 for the scattered light in the measurement area 101 is not particularly limited as long as the projection optical system 10 and the light-receiving optical system 20 are approximately aligned in a straight line when viewed from the upper surface. The light-receiving optical system 20 can measure the scattered light from the measurement area 101 from an oblique angle above or directly above. In this embodiment, the light-receiving optical system 20 is configured such that the objective lens 21 faces the measurement area 101 above the substrate 100 on the side opposite to the projection optical system 10, and the measurement area 101 is sandwiched between the light-receiving optical system 20 and the projection optical system 10. The angle of the light-receiving optical system 20 is appropriately adjusted accordingly to match the incident angle of the projection optical system 10.

[0119] Figure 4 (b) shows the measurement taken by incident light when viewed in the direction of arrow DC. Figure 4 (a) Section AA'. In Figure 4 In this case, the incident light L1 is obliquely incident, having a horizontal component L11 in the X direction and a vertical component L12 in the Z direction. The incident light L1 is obliquely incident on the substrate 100, thereby causing the transmitted light L4 to propagate obliquely within the substrate 100. Therefore, the transmitted light L4, like the incident light, has a horizontal component L41 in the X direction and a vertical component L42 in the Z direction. Figure 4 In (b), scattered light that depends on the horizontal component in the X direction and the vertical component in the Z direction can be generated.

[0120] Figure 4 (c) shows the measurement taken by incident light when viewed in the direction of arrow DD. Figure 4 (a) BB' section. In Figure 4 In (c), the incident light L1 is obliquely incident, having a horizontal component L13 in the Y direction and a vertical component L14 in the Z direction. Because the incident light L1 is obliquely incident on the substrate 100, the transmitted light L4 propagates obliquely inside the substrate 100, having the same horizontal component L43 in the X direction and a vertical component L44 in the Z direction as the incident light. Figure 4 In (c), scattered light that depends on the horizontal component in the X direction and the vertical component in the Z direction can be generated.

[0121] The above, such as Figure 3 and Figure 4As shown, in the measurement process, measurement data dependent on horizontal components in at least two directions can be obtained in the measurement area 101.

[0122] Furthermore, the above measurement process is illustrated using a two-direction measurement approach, but it is not limited to two directions. For example, the measurement directions can be three, four, five, or more. Among multiple measurement directions, equally spaced measurement directions are preferred.

[0123] <Example 1> Figure 5 This is a summary diagram illustrating the measurement process. Figure 5 In this process, the evaluation apparatus 1 measures the intensity of scattered light by scanning the measurement area 101 across the entire surface of the substrate 100. The scanning of the measurement area 101 is achieved by moving the stage 30 or by moving the housing 40 that supports the light-emitting optical system 10 and the light-receiving optical system 20.

[0124] exist Figure 5 In (a), the substrate 100 uses reference point P as the reference position for substrate position information. Figure 5 In (a), the projection optical system 10 and the receiving optical system 20 are configured to measure the horizontal component of the scattered light dependent on the X direction, respectively. The projection optical system 10 and the receiving optical system 20 may be configured such that at least one of them measures the horizontal component of the scattered light dependent on the X direction.

[0125] exist Figure 5 In (a), the measurement area 101 scans the laser by moving along the X direction of the substrate 100. When the measurement area 101 completes scanning along the X direction from the left end to the right end of the substrate 100, it moves a predetermined feed width distance relative to the feed direction (Y direction). After moving in the feed direction, the measurement area 101 is scanned again along the X direction from the left end to the right end of the substrate 100. Through this scanning in the X direction and the feed movement in the Y direction, the entire surface of the substrate 100 can be measured.

[0126] exist Figure 5 In (b), the reference point P represents the intersection with... Figure 5 (a) is at the same location as the reference point P. Figure 5 In (b), the projection optical system 10 and the receiving optical system 20 are respectively configured to measure the scattered light dependent on the horizontal component of the Y direction. The projection optical system 10 and the receiving optical system 20 can be configured such that at least one of them measures the scattered light dependent on the horizontal component of the Y direction.

[0127] exist Figure 5In (b), the measurement area 101 scans the laser by moving along the Y-direction of the substrate 100. When the measurement area 101 completes the scan along the Y-direction from the top to the bottom of the substrate 100, it moves a predetermined feed width distance relative to the feed direction (X-direction). After moving in the feed direction, the measurement area 101 again scans along the Y-direction from the top to the bottom of the substrate 100. Through this scanning movement in the Y-direction and the feed movement in the X-direction, the entire surface of the substrate 100 is measured.

[0128] <Example 2> Figure 6 This is a summary diagram illustrating the measurement process. Figure 6 In this process, the evaluation apparatus 1 measures the intensity of scattered light by scanning the measurement area 101 across the entire surface of the substrate 100. The scanning of the measurement area 101 is achieved by rotating and planar moving the stage 30 or rotating the stage 30 and planar moving the housing 40.

[0129] exist Figure 6 In (a), the measurement area 101 is scanned by rotating the substrate 100 in the rotational direction. At the end of the scan, which involves rotating the substrate 100 one revolution, the measurement area 101 moves a predetermined feed width relative to the feed direction (Y direction). Alternatively, the measurement area 101 can be scanned seamlessly by moving relative to the feed direction while simultaneously rotating the substrate 100 one revolution. The feed direction is either from the outer periphery of the substrate 100 towards the center point, or vice versa. Figure 6 In (a), the starting position in the feed direction is the reference point P, and the ending position is the center point. The starting and ending positions can also be reversed. The reference point P is not particularly limited as long as it is on the outer periphery of the substrate 100. After moving in the feed direction, the measurement area 101 is scanned by rotating the substrate 100 one revolution again. Through this rotating scanning and feed movement, the entire surface of the substrate 100 can be measured. Figure 6 In (a), the light-emitting optical system 10 and the light-receiving optical system 20 are configured to measure scattered light in the tangential direction of the concentric circles of the substrate 100.

[0130] exist Figure 6 In (b), the measurement area 101 is scanned by rotating the substrate 100 in the rotational direction. When the scan is completed by rotating the substrate 100 one revolution, the measurement area 101 moves a distance of a predetermined feed width relative to the feed direction (X direction). Furthermore, with... Figure 6 (a) Similarly, the measurement area 101 can also be scanned by moving a distance equal to the transport width relative to the feed direction while the substrate 100 rotates one revolution. Furthermore, the feed width in the X and Y directions is the same distance. Figure 6 In (b), the starting position of the feed direction is... Figure 6 (a) With the same reference point P, the ending position is the center point. The starting and ending positions can also be opposite. Additionally, the starting position can be any point on the outer perimeter different from the reference point P. Figure 6 In the measurement of (b), by means of... Figure 6 (a) Measurement begins with the substrate rotated 90 or 270 degrees at the start of the measurement, thereby aligning the starting position with the reference point P. After moving the substrate 100 a distance of feed width in the feed direction, the measurement area 101 is scanned by rotating the substrate 100 another full revolution. Through this rotating scanning and feed movement, the entire surface of the substrate 100 can be measured. Figure 6 In (b), the light-emitting optical system 10 and the light-receiving optical system 20 are configured to measure the scattered light in the normal direction of the concentric circles of the substrate 100.

[0131] pass Figure 6 (a) Figure 6 In measurement step (b), the scattered light depends on the horizontal components of the light in the two orthogonal directions of the concentric circles of the substrate 100: the tangential direction and the normal direction. Furthermore, the measurement area 101 is not limited to measuring scattered light orthogonal to the tangential and normal directions. The measurement area 101 can be in any direction orthogonal to the movement direction of the substrate 100, thereby enabling the measurement of the horizontal components of the scattered light depending on the two orthogonal directions.

[0132] exist Figure 6 (a) and Figure 6 (b) illustrates an example where the optical system fixes the X-direction as the measurement direction and measures orthogonal scattered light in a measurement region 101 with the same substrate position information by rotating the substrate 100 by 270 degrees or 90 degrees. Alternatively, the optical system can be rotated by 90 degrees or 270 degrees so that the X and Y directions become the measurement directions, and orthogonal scattered light is measured in a measurement region 101 with the same substrate position information.

[0133] <Example 3> Figure 7 This is a summary diagram illustrating the measurement process. Figure 7 In this measurement area 101, the measurement region 101 is rectangular or linear. The measurement region 101 has width in the scanning direction, thereby expanding the measurement range and shortening the measurement time. Figure 7 In Embodiment 3, similarly to Embodiment 2, the measurement area 101 is scanned by rotating and planar moving the stage 30, or by rotating the stage 30 and planar moving the housing 40. In Embodiment 3, the long side of the measurement area 101 is tilted relative to the scanning direction (rotation direction). The tilt angle is preferably 45 degrees relative to the scanning direction.

[0134] exist Figure 7 In (a), the long side of the measurement area 101 is tilted at 45 degrees relative to the scanning direction. The scanning area A measures the intensity of scattered light on the entire surface of the substrate 100 by moving from the outer periphery (i.e., reference point P) of the substrate 100 toward the center point in the feed direction (Y direction) while rotating the substrate 100.

[0135] exist Figure 7 In (b), the measurement area 101 is measured by rotating the substrate 100 while moving from... Figure 7 (a) The reference point P is moved toward the center point in the feed direction (X direction) to measure the intensity of scattered light across the entire surface of the substrate 100.

[0136] exist Figure 7 (a) Figure 7 In (b), similar to Example 2, an example is shown of measuring orthogonal scattered light in a measurement area 101 with the same substrate position information by fixing the orientation of the optical system and rotating the substrate 100 by 270 degrees or 90 degrees. However, it is also possible to measure orthogonal scattered light in a measurement area 101 with the same substrate position information by rotating the optical system side by 270 degrees or 90 degrees.

[0137] The rotational scanning measurements according to Examples 2 and 3 have advantages over the measurements of Example 1 in terms of shorter measurement time, suppression of resonance of the stage 30, and improved tracking of the light spot relative to the deflection of the substrate 100.

[0138] Figure 8 (a) Figure 8 (b) shows the passage Figure 7 The directions of the inspection objects measured by the strong scattered light in each measurement process of (a) and (b) are shown. The dashed lines indicate the scanning path of the measurement area 101 during feed movement. The solid lines indicate the directions of strong scattering along the scanning path.

[0139] exist Figure 8 (a) Figure 8 In (b), the direction of strong scattering depends on the tilt angle of the measurement area 101, which is tilted by 45 degrees. (Comparison) Figure 8 (a) Figure 8 (b) The direction of stronger scattering is offset by 90 degrees within the substrate 100, and the resulting direction of stronger scattering is opposite and orthogonal.

[0140] Figure 8 (c) shows that Figure 8 (a) Figure 8 (b) The result after overlap. According to Figure 8(c) It can be seen that if a measurement area 101 is of interest, the directions of strong scattering are orthogonal. Thus, in the measurement process, by measuring the scattered light in a way that makes the directions of strong scattering different across the entire surface of the substrate 100, high-speed measurement can be performed without missing any objects present on the substrate 100.

[0141] As shown in Examples 1 to 3 above, in the measurement process, by scanning a laser on the surface of the substrate 100, scattered light is measured in multiple measurement areas 101 of the substrate 100, thereby enabling measurement data of the entire surface of the substrate 100 to be obtained based on multiple measurement areas 101.

[0142] In the measurement process, two measurement directions (a first direction and a second direction) are set relative to the scanning direction of the scanning laser. In the first embodiment, the measurement direction in the X direction is set for the scanning direction in the X direction, and the measurement direction in the Y direction is set for the scanning direction in the Y direction. In the second embodiment, the scanning direction corresponds to the rotation, and the measurement direction is set as the tangent direction of the concentric circles generated by the rotation and the normal direction of the concentric circles generated by the rotation, respectively. In addition, in the first and second embodiments, examples are shown where the scanning direction and the measurement direction are in the same direction, but the possibility of the measurement direction being tilted relative to the scanning direction is not excluded.

[0143] Figure 9 This is an explanatory diagram of the measurement direction set relative to a rotation-based scanning direction. In Figure 9 In this method, scanning is performed by rotating the substrate 100 in an in-plane direction and irradiating it with a laser along a rotation track C1. The rotation track C has multiple tracks with different radii. Alternatively, it can be a helical rotation track whose radius gradually changes while the substrate 100 is rotated. Figure 9 The explanation will focus on the measurement of points Q and R on the rotating track C1.

[0144] Figure 9 (a) is an explanatory diagram of the scanning direction of the substrate 100. The laser scans at point Q along the scanning direction S1 in the X direction and at point R along the scanning direction S2 in the Y direction.

[0145] Figure 9 (b) is an illustration of the measurement direction using an optical system located in the first direction (in the example, the light-receiving optical system 20). The scattered light is measured at point Q in the measurement direction M11 and at point R in the measurement direction M21. The measurement direction is also the same when using the light-projecting optical system 10.

[0146] Figure 9(c) is an illustration of the measurement direction using an optical system located in the second direction (in the example, the light-receiving optical system 20). The scattered light is measured at point Q in the measurement direction M12 and at point R in the measurement direction M22. The measurement direction is also the same when using the projection optical system 10.

[0147] exist Figure 9 (b) and Figure 9 In (c), the position of the optical system is fixed, and points Q and R on the substrate 100 are measured by rotating the substrate 100.

[0148] Figure 9 (d) is an explanatory diagram of the measurement directions relative to the scanning direction. At point Q, scattered light is measured in the first measurement direction M11 and the second measurement direction M12 relative to the scanning direction S1. At point R, scattered light is measured in the first measurement direction M21 and the second measurement direction M22 relative to the scanning direction S2. Here, the first measurement directions M11 and M21 relative to the scanning directions S1 and S2 are the same direction, and the second measurement directions M12 and M22 relative to the scanning directions S1 and S2 are also the same direction.

[0149] In addition, Figure 9 In (d), the in-plane direction of the first measurement direction can also be set to a first angle relative to the rotation track, and the in-plane direction of the second measurement direction can be set to a second angle relative to the rotation track. The first angle and the second angle are angles relative to the tangent of the rotation track. In a preferred embodiment, the first angle is 45 degrees relative to the tangent of the rotation track, and the second angle is -45 degrees relative to the tangent of the rotation track. That is, the measurement direction is tilted by 45 degrees relative to the scanning direction.

[0150] As described above, by setting the first measurement direction and the second measurement direction respectively relative to the scanning direction, the scattered light measured in the multiple measurement areas 101 of the substrate 100 becomes the same measurement direction, thereby enabling the acquisition of appropriate measurement data for the entire surface of the substrate 100.

[0151] Figures 3 to 9 The measurement process in two directions includes a first measurement process for measuring in the first direction and a second measurement process for measuring in the second direction. In this embodiment, the second measurement process is performed after the first measurement process. By using the same optical system for measurement, differences in measurement data caused by individual differences in the output intensity of the laser output unit 11 and individual differences in the light sensitivity of the light-receiving sensor 24 can be suppressed. In particular, the scattered light caused by the strain of the processed modified layer is extremely weak, and even small individual differences in light sensitivity can affect the measurement data.

[0152] In both the first and second measurement steps, the position of the optical system is fixed, and the laser is scanned by rotating and moving the substrate 100. In the first measurement step, the scattered light of a region is measured separately using the fixed-position optical system, and in the second measurement step, the orientation of the measurement region is changed to measure the scattered light separately.

[0153] When performing two measurement steps (first and second) using an optical system, the measurement data from both steps include information on the intensity of scattered light and the position of the stage. The measurement data from the first step includes the intensity of scattered light measured in a first direction for a specific measurement area and information on the position of the first stage. The measurement data from the second step includes the intensity of scattered light measured in a second direction for the measurement area and information on the position of the second stage.

[0154] In the first and second measurement steps, the intensities of scattered light measured separately in the same measurement area of ​​the substrate 100 are combined in the synthesis step described later. The intensities of scattered light from the same measurement area after the synthesis process are designated to have the same substrate position information. In the first and second measurement steps, since the position of the optical system is fixed, it is necessary to change the first and second directions relative to the measurement area by rotating the substrate 100 in each step. Therefore, when the same substrate position information is referenced in the first and second measurement processes, the first stage position information and the second stage position information indicate different stage positions.

[0155] The position information of the first mounting stage and the second mounting stage are aligned based on the substrate position information of the reference point P on the substrate 100. Position alignment refers to aligning the first and second mounting stage position information, which represent different mounting stage positions, as information representing the same substrate position information. Multiple reference points can be set on the substrate 100. In the first and second measurement steps, the mounting stage position information aligned with the substrate position information serving as reference points is acquired.

[0156] In this embodiment, the position alignment process is performed in at least one of the measurement and synthesis processes. As long as the stage position information of the two measurement data is used as the same substrate position information for position alignment to obtain the synthesized data of the intensity of scattered light in both directions, the timing of the position alignment process is not limited.

[0157] In the first measurement step, first measurement data including the position information of the first stage and the intensity of scattered light in a first direction are acquired. The control unit 50 rotates and / or moves the stage 30 in a plane to acquire the first measurement data across the entire surface of the substrate 100. In the first measurement step, substrate position information, which is used as at least one reference point in the position alignment process, and first stage position information aligned with the substrate position information are acquired.

[0158] In the second measurement step, second measurement data including the position information of the second stage and the intensity of the scattered light in the second direction are acquired. The control unit 50 rotates and / or moves the stage 30 in a plane to acquire the second measurement data across the entire surface of the substrate 100. In the second measurement step, substrate position information used as at least one reference point in the position alignment process and second stage position information aligned with the substrate position information are acquired.

[0159] The first and second measurement steps can be performed simultaneously using two optical systems. As described above, even in the event of individual differences between the two optical systems, measurements in both directions can be performed simultaneously by correcting for differences in measurement data caused by these individual differences. This further enables the measurement process to be accelerated.

[0160] When the first and second measurement steps are performed simultaneously in two optical systems, the measurement data from the first and second measurement steps include the intensity of the scattered light and the stage position information or substrate position information. In simultaneous measurement, the two measurement data include the intensity of the scattered light for the same measurement area and the same substrate position information. Alternatively, in simultaneous measurement, the positional relationship between the substrate position information of the two measurement data is predefined, and a correspondence is established between the measurement data that respectively become the same substrate position information according to the defined positional relationship.

[0161] <Controls for position alignment processing> Figure 10 This is an explanatory diagram regarding the control of position alignment processing in the first and second measurement steps. Here, an example of control is shown in a measurement step based on rotational scanning. Figure 10 In the diagram, a solid line represents substrate 100 measured in the first measurement process, and a dashed line represents substrate 100' measured in the second measurement process. Substrate 100' represents the state in which substrate 100 has been rotated by 270 degrees (3π / 2). Point P on substrate 100 and point P' on substrate 100' represent the same substrate position.

[0162] exist Figure 10In this configuration, the optical system (light-receiving optical system 20) is fixed at a position for measuring points P and P'. Point P is a reference point used for aligning the stage position information and the substrate position information. The reference point is, for example, pre-set to be aligned with the end or center of the substrate 100.

[0163] In the first measurement process, the control unit 50 controls the stage 30 to position it relative to the substrate position information at the reference point P, which serves as the starting position. Here, for position alignment, the first stage position information W1 is associated with the substrate position information S1 at the reference point P. The control unit 50 rotates the stage 30 (substrate 100) while simultaneously moving the stage 30 in the feed direction D1 (Y direction) to acquire first measurement data. This first measurement data, taken as the measurement time t, becomes a time-series data of the scattered light intensity I1(t) and the first stage position information W1(t).

[0164] In the second measurement process, the control unit 50 rotates and moves the stage 30 planarly so that the reference point P / P', which serves as the starting position, becomes an overlapping position. Figure 10 In this process, the stage 30 is rotated 270 degrees, and then moved by a radius r in the X and Y directions. Here, for position alignment processing, the second stage position information W2 is associated with the substrate position information S1 of the reference point P / P'. The control unit 50 rotates the stage 30 (substrate 100) and moves the stage 30 in the feed direction D2 (X direction) to acquire second measurement data. The second measurement data, as the measurement time t, becomes time series data of the scattered light intensity I2(t) and the second stage position information W2(t).

[0165] In the case of rotational scanning, the starting positions of the first and second measurement processes are set as reference points P / P', ensuring their respective rotational paths are aligned. Therefore, if the first stage position information W1 and the second stage position information W2 at the starting position are aligned with the substrate position information at reference point P, the substrate position information in the subsequent time-series data will also be consistent. The time-series data of the first and second measurement data after position alignment processing includes substrate position information S(t), scattered light intensity I1(t), and scattered light intensity I2(t).

[0166] Furthermore, the first and second measurement steps are not limited to configurations that align the starting positions. If the substrate position information of the reference point P and the corresponding first and second stage position information are obtained in the first and second measurement steps, the substrate position information of the first and second measurement data can be aligned.

[0167] In addition, in planar moving scan, if the substrate position information that serves as the reference point and the corresponding first stage position information and second stage position information can be obtained, then the substrate position information of the first measurement data and the second measurement data can be aligned.

[0168] This specification describes an example where the reference point is set at the end, but the rotation center of the stage 30 (substrate 100) can also be used as the reference point. In this case, in the first measurement step, the substrate 100 is rotated while moving in a first movement direction (e.g., the X direction) to obtain first measurement data. In the second measurement step, the substrate 100 is rotated while moving in a second movement direction (e.g., the Y direction) to obtain second measurement data. The first and second movement directions are feed directions, corresponding to the radial directions of the substrate 100. The starting position of the first and second measurement steps is the rotation center set as the reference point, and the entire surface is measured by feed movement towards the outside of the substrate 100. In this case, the ending position of the measurement is the outer end of the substrate 100.

[0169] By setting the feed widths of the first and second measurement steps to the same distance, the feed positions r of the first and second measurement data in the radial direction are consistent. Furthermore, in the second measurement step, by starting the measurement with the substrate 100 rotated 90 degrees or 270 degrees from the start of the first measurement step, the end positions of the measurement on the substrate 100 can be made consistent. By aligning the start and end positions of the measurement on the substrate 100, the substrate position information of the first and second measurement data is made consistent, which is therefore more preferable.

[0170] <Measurement Data> Figure 11 Measurement data for the measurement process according to Example 3 are shown. Figure 11 (a) is the measurement data from the first measurement process, and reflects... Figure 8 (a) is an image of the intensity of scattered light in the direction of strong scattering. Figure 11 (b) is the measurement data from the second measurement process, and it reflects... Figure 8 (b) is an image of the intensity of scattered light in the direction of strong scattering. Figure 11 The measurement data is displayed in descending order of scattered light intensity, using red, yellow, green, and other colors to represent the corresponding intensities. Areas with high scattered light intensity can be interpreted as indicating the presence of a greater number of objects to be inspected.

[0171] Compare Figure 11 (a) Figure 11(b) The intensity of each scattered light is represented at the position where the intensity distribution is reversed, as shown in the butterfly pattern. This difference in intensity distribution is understood to be due to the orthogonal directions of strong scattering caused by the difference in measurement direction. Furthermore, it is difficult to fully grasp the object to be inspected on the substrate 100 by measuring only from one direction.

[0172] <Synthesis Process> The control unit 50 generates composite data (composite process) based on measurement data in the first and second directions within the measurement area. The control unit 50 generates composite data by performing a composite processing method that averages the measurement data from the first and second measurement processes. In this embodiment, averaging involves dividing the sum of the scattered light intensities from each location information by 1 / 2. Furthermore, averaging is not limited to methods such as additive averaging, multiplicative averaging, or harmonic averaging. Moreover, the composite processing is not limited to averaging as long as it employs a calculation method that can suppress the dependence of measurement data from different measurement directions on scattered light; other calculation methods can be used.

[0173] In addition, the compositing process performs position alignment processing on the position information of the first measurement data and the second measurement data to generate composite data. The control unit 50 acquires first measurement data including scattered light intensity I1(t) and first stage position information W1(t), and second measurement data including scattered light intensity I2(t) and second stage position information W2(t), generating position alignment data having substrate position information S(t), scattered light intensity I1(t), and scattered light intensity I2(t). The control unit 50 generates composite data by averaging the scattered light intensities of each recorded position alignment data.

[0174] Figure 12 The synthesis data generated during the synthesis step is shown. (Compared to...) Figure 11 Similarly, the composite data is displayed according to color categories, such as red, yellow, and green, in descending order of scattered light intensity. The composite data is an average of the intensity values ​​from multiple measurements. By combining measurement data from two directions, the composite data suppresses the influence of inverted intensity distribution representation. Therefore, the composite data can more accurately represent the intensity distribution of scattered light on substrate 100.

[0175] The substrate 100 is evaluated for quality by using composite data as described above. For example, in the composite data, areas with high scattered light intensity can be evaluated as areas with significant defects or processing alteration layers, which are objects of inspection.

[0176] Symbol Explanation 1 Evaluation device 10 Flooding Optical System 11 Laser Output Section 12 filters 13 Wavelength Plate 14 Condensing Lenses 20 Light-receiving optical system 21 Objectives 22 Imaging Lenses 23 slits 24 light sensors 30 mounting platforms 31 Three-axis drive unit 32 Rotary Drive Unit 40 housing 50 Control Department 51 Platform Control Unit 52 Signal Processing Department 53 Synthesis Processing Department 100 substrates.

Claims

1. A substrate evaluation method using a laser light scattering method, the substrate evaluation method comprising: a measurement step of measuring, for each measurement region on a substrate surface, scattered light using an optical system located in a first direction and a second direction with the measurement region as a reference, to obtain first measurement data and second measurement data; and a synthesis step of synthesizing the first measurement data and the second measurement data to generate synthesized data.

2. The substrate evaluation method according to claim 1, wherein The first direction and the second direction are different in an in-plane direction of the substrate.

3. The substrate evaluation method according to claim 2, wherein The first direction and the second direction are orthogonal in their in-plane directions.

4. The method of evaluating a substrate according to claim 1, wherein, The optical system includes a light-receiving optical system that receives scattered light generated by the substrate, In the measurement step, the scattered light is measured using the light-receiving optical system located in the first direction and the second direction with the measurement region as a reference, to obtain the first measurement data and the second measurement data.

5. The method of claim 1, wherein The optical system includes a light-irradiation optical system that irradiates laser light to the surface of the substrate, In the measurement step, the scattered light is measured using the light-irradiation optical system located in the first direction and the second direction with the measurement region as a reference, to obtain the first measurement data and the second measurement data.

6. The method of evaluating a substrate according to claim 1, wherein, The measurement step includes measuring the scattered light in a plurality of the measurement regions of the substrate by scanning laser light on the substrate surface.

7. The method of evaluating a substrate according to claim 6, wherein The first direction and the second direction are set for a scanning direction of the scanning.

8. The method of evaluating a substrate according to claim 6, wherein, The measurement region is set to be inclined with respect to the scanning direction of the scanning.

9. The method of evaluating a substrate according to claim 1, wherein, The measurement step includes irradiating laser light to the surface of the substrate while rotating the substrate in an in-plane direction, and measuring the scattered light.

10. The method of evaluating a substrate according to claim 9, wherein, In the measurement step, the laser light is irradiated to a rotation track of the substrate by rotating the substrate in an in-plane direction, An in-plane direction of the first direction and an in-plane direction of the second direction are set at a first angle and a second angle with respect to the rotation track.

11. The method of evaluating a substrate according to claim 1, wherein, The measurement step includes a first measurement step and a second measurement step, In the first measurement step and the second measurement step, the scattered light is measured by changing the direction of the measurement region with respect to the position-fixed optical system, to obtain the first measurement data and the second measurement data, In the synthesis step, positional information of the first measurement data and the second measurement data is positionally aligned to generate the synthesized data.

12. The method of claim 11, wherein, In the first measurement step, the laser light is scanned by moving in a first movement direction while rotating the substrate in an in-plane direction, to obtain the first measurement data, In the second measurement step, the laser light is scanned by moving in a second movement direction different from the first movement direction while rotating the substrate in an in-plane direction, to obtain the second measurement data.

13. The method of claim 12, wherein, In the second measurement step, the measurement is started in a state where the substrate is rotated by 90 degrees or 270 degrees from the start of the measurement in the first measurement step.

14. The method of claim 11, wherein, In the first measurement step and the second measurement step, the same optical system is used to measure the scattered light.

15. The substrate evaluation method according to any one of claims 1 to 14, wherein, The measurement region is linear or rectangular.

16. A substrate evaluation apparatus using a laser scattering method, the substrate evaluation apparatus comprising: an irradiation optical system that irradiates a substrate with laser light; a light-receiving optical system that measures scattered light; a stage that has a three-axis drive unit that moves a substrate plane; and a control unit that controls the stage to move to a position that is a reference for the substrate, the position being a respective start position for a first measurement and a second measurement.

17. The substrate evaluation device according to claim 16, wherein the stage also has a rotation drive unit that rotates the substrate, the control unit controls the stage to move in different feed directions in the first measurement and the second measurement by the three-axis drive unit while rotating the stage by the rotation drive unit.

18. The substrate evaluation device according to claim 16 or 17, wherein the control unit position-aligns position information of two measurement data measured by the first measurement and the second measurement, and performs a synthesis process as synthesis data.

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