Spectrometry device and spectrometry method

Abstract

In order to provide a spectrometry device that makes it possible to improve detection sensitivity with respect to a change in physical property value such as expansion of a sample which is subjected to energy transfer with, for example, infrared radiation, that has high resolution, and that enables accurate autofocus, the present invention has the following configuration.　Provided is a spectrometry device comprising: an electromagnetic wave source that generates electromagnetic waves to be emitted to a prescribed region of a sample; an objective lens that focuses electromagnetic waves on the prescribed region; two shared focal point detectors that detect electromagnetic waves reflected by the sample; and an in-focus position determination mechanism that performs differential calculation or lock-in detection calculation on a signal calculated by dividing a difference signal and a sum signal of output of each of the two shared focal point detectors and that determines, as an in-focus position, a position where a peak value is obtained.

Description

Spectroscopic measurement device and spectroscopic measurement method

[0001] The present invention relates to a spectroscopic measurement device and a spectroscopic measurement method.

[0002] A spectrometer is a device that analyzes the composition of a substance or identifies foreign matter contained in a substance by measuring the absorption curve, or absorption spectrum, of the substance relative to the wavelength of light. Because infrared light, which has a wavelength about 10 times that of visible light, is generally used to analyze molecular vibrations, the spatial resolution is limited to the order of 10 μm by the diffraction limit, which is proportional to the wavelength of the light used.

[0003] Patent Document 1 discloses a spectroscopic measurement device that, in order to improve resolution, is provided with two confocal detectors that detect electromagnetic waves reflected by a sample, and calculates changes in the physical properties of the sample when an energy beam is irradiated onto a specified area based on the outputs of the confocal detectors.

[0004] Japanese Patent Application Laid-Open No. 2022-134422

[0005] Patent Document 1 states that "the provision of two confocal detectors also enables autofocusing," and describes a method for achieving this by adjusting the value of (PD2-PD1) / (PD2+PD1) to zero (paragraph

[0025] ). The inventors conducted follow-up experiments and found that the point where the above equation becomes zero may not necessarily be the in-focus position. Figure 4 of Patent Document 1 assumes that PD1 and PD2 are perfectly symmetrical. This assumption holds true for a sample with a mirrored surface, but real samples usually have uneven surfaces, and it is rare for PD1 and PD2 to be perfectly symmetrical. Therefore, the inventors found that the point where the value of (PD2-PD1) / (PD2+PD1) becomes zero is often not the in-focus position.

[0006] The present invention was made while considering improvements to the autofocus method described in Patent Document 1, and its purpose is to provide a spectroscopic measurement device and spectroscopic measurement method that have high resolution and are capable of accurate autofocusing.

[0007] To achieve the above object, the present invention is configured as follows: A spectroscopic measurement device comprising an electromagnetic wave source that generates electromagnetic waves to be irradiated onto a predetermined area of ​​a sample, an objective lens that focuses the electromagnetic waves onto the predetermined area, two confocal detectors that detect the electromagnetic waves reflected by the sample, and a focus position determination mechanism that performs differential calculation or lock-in detection calculation on a signal obtained by dividing the difference signal and sum signal of the outputs of the two confocal detectors, and determines the position at which the peak value is obtained as the focus position.

[0008] Also, the spectroscopic measurement method includes the steps of irradiating a predetermined area of ​​a sample with electromagnetic waves, acquiring the outputs of two confocal detectors provided at different positions that detect the electromagnetic waves reflected from the sample due to the irradiation of the electromagnetic waves, and performing a differential calculation or lock-in detection calculation on the signal obtained by dividing the difference signal and sum signal of each output, and determining the position at which the peak value is obtained as the focus position.

[0009] According to the present invention, it is possible to provide a spectroscopic measurement device and a spectroscopic measurement method that have high resolution and are capable of accurate autofocusing.

[0010] 1 is a schematic configuration diagram of an example of a spectroscopic measurement device according to Example 1. FIG. 2 is a diagram illustrating an energy beam and probe light irradiated onto a sample. FIG. 3 is a diagram illustrating the configuration of a confocal detector. FIG. 4 is a diagram illustrating the relationship between the amount of light detected by a confocal detector and the amount of displacement. FIG. 5 is a diagram illustrating the relationship between the amount of light detected by two confocal detectors and the amount of displacement. FIG. 6 is a diagram illustrating the relationship between the sum of the amounts of light detected by two confocal detectors and the amount of displacement. FIG. 7 is a diagram illustrating the ratio between the difference and the sum of the amounts of light detected by two confocal detectors, and the relationship between the differential value thereof and the amount of displacement. FIG. 8 is a diagram illustrating the reason why the amount of detected light differs between focal positions +L and -L. FIG. 9 is a diagram illustrating an example of XY scanning of a spectroscopic measurement device according to Example 2. FIG. 10 is a diagram illustrating another example of XY scanning of a spectroscopic measurement device according to Example 2. FIG. 11 is a diagram illustrating an example of a confocal detector of a spectroscopic measurement device according to Example 3. FIG. 12 is a diagram illustrating an example of energy beam irradiation of a spectroscopic measurement device according to Example 4. FIG. 13 is a diagram illustrating another example of energy beam irradiation of a spectroscopic measurement device according to Example 4.

[0011] Hereinafter, an embodiment of the spectroscopic measuring device of the present invention will be described with reference to the drawings.

[0012] The overall configuration of the spectroscopic measurement device of Example 1 will be described with reference to Fig. 1. The device configuration as hardware of the present invention is basically the same as that described in Japanese Patent Application Laid-Open No. 2022-134422, which is the prior application of the present application.

[0013] 1, the vertical direction is the Z direction, and the horizontal directions are the X direction and the Y direction. The spectroscopic measurement device includes a stage mechanism system on which the sample 113 is placed, an energy imparting system that imparts energy to the sample 113, a measurement system that measures the physical property values ​​of the sample 113, and a control system that processes data output from each part and controls each part.

[0014] The stage mechanism system has an XY stage 112 on which a sample 113 is placed and which moves in the X and Y directions. By moving the XY stage 112 in the X and Y directions, a given region on the surface of the sample 113 can be analyzed.

[0015] The energy deposition system includes an energy source 100, beam expander lenses 101 and 102, a partial reflection mirror 103, an energy detector 104, a dichroic mirror 110, and an objective lens 111. The dichroic mirror 110 and the objective lens 111 are also used by the measurement system.

[0016] The energy source 100 generates an energy beam 500, for example an infrared beam, that imparts energy to the sample 113. The beam diameter of the energy beam 500 is expanded by beam expander lenses 101 and 102, and then directed toward a partial reflection mirror 103. The partial reflection mirror 103 transmits a portion of the energy beam 500 toward an energy detector 104 and reflects the remainder toward the sample 113. The energy detector 104 measures the intensity of the energy beam 500 that has transmitted through the partial reflection mirror 103. The energy beam 500 reflected by the partial reflection mirror 103 passes through a dichroic mirror 110, is focused by an objective lens 111, and then is irradiated onto the sample 113. The sample 113 irradiated with the energy beam 500 absorbs the imparted energy and undergoes changes in its physical properties, such as thermal expansion.

[0017] The measurement system includes a light source 120, a collimator lens 121, a beam splitter 122, a filter 123, a condenser lens 124, a half mirror 125, pinholes 126 and 128, photodetectors 127 and 129, a dichroic mirror 110, and an objective lens 111. Although the present embodiment refers to the light source as a "light source," it is technically more accurate to use the term "electromagnetic wave source" because the effects of the present invention can be achieved even if the irradiated electromagnetic waves are other than "light." Furthermore, although "condenser lenses" and "photodetectors" should be called "electromagnetic wave focusing lenses" and "electromagnetic wave detectors," respectively, the term "light" is used for ease of understanding.

[0018] The light source 120 generates probe light 501, such as a visible light beam or an ultraviolet light beam, for measuring changes in the physical properties of the sample 113. The probe light 501 generated by the light source 120 has a shorter wavelength than the energy beam 500 and is preferably a beam that is focused to a smaller spot, such as a green or blue light beam. The probe light 501 is converted into a substantially parallel beam by a collimator lens 121, then passes through a beam splitter 122 and a filter 123, and heads toward a dichroic mirror 110. The dichroic mirror 110 reflects the probe light 501 toward an objective lens 111. The probe light 501 reflected by the dichroic mirror 110 is focused by the objective lens 111 and then irradiated onto the sample 113.

[0019] The energy beam 500 and probe light 501 irradiated onto the sample 113 will be described with reference to FIG. 2 . As described above, both the energy beam 500 and the probe light 501 are focused by the objective lens 111 and irradiated onto the sample 113. The probe light 501 has a smaller beam diameter than the energy beam 500 and is irradiated onto a narrower area than the area irradiated by the energy beam 500. This allows for measurement of changes in physical properties of the area irradiated by the energy beam 500 with high spatial resolution. In particular, when the probe light 501 is a visible light beam, the beam diameter of the probe light 501 focused on the surface of the sample 113 is approximately 0.5 μm. Furthermore, by using a confocal detector in the measurement system, the spatial resolution of the measurement system is approximately 0.3 μm. The changes in physical properties to be measured include changes in the displacement and curvature of the surface of the sample 113 due to expansion caused by absorbing the energy beam 500, changes in the surface refractive index and reflectance, and the like.

[0020] The confocal detector will be described with reference to Figures 3A and 3B. The confocal detector is configured so that when light emitted from a point light source is focused on the surface of the sample, light reflected from the sample is focused on the detection plane. Specifically, a light source 120, a collimator lens 121, a beam splitter 122, an objective lens 111, a sample 113, a condenser lens 124, a pinhole 126, and a photodetector 127 are arranged as illustrated in Figure 3A. The probe light 501 emitted from the point light source of the light source 120 is converted into a parallel beam by the collimator lens 121, reflected by the beam splitter 122, and incident on the objective lens 111. The objective lens 111 converges the probe light 501 to form a focus.

[0021] When the focal point is on the surface of the sample 113, the reflected probe light 501 passes through the objective lens 111, the beam splitter 122, and the condenser lens 124 along the optical path indicated by the solid line in FIG. 3A and is focused at the pinhole 126. As a result, most of the probe light 501 reflected by the sample 113 passes through the pinhole 126 and is detected by the photodetector 127. When the sample 113 expands due to irradiation with the energy beam 500 and the surface is displaced as indicated by the dotted line in FIG. 3A, the probe light 501 travels along the optical path indicated by the dotted line and is not focused at the pinhole 126. As a result, the amount of light that passes through the pinhole 126 and is detected by the photodetector 127 is reduced compared to the case of the optical path indicated by the solid line. In other words, the amount of light detected by the photodetector 127 changes depending on the amount of displacement of the surface of the sample 113, and therefore the change in the physical properties of the sample 113 to which energy has been applied can be measured by the photodetector 127.

[0022] 3B is a graph showing the relationship between the detected light amount I of the confocal detector and the displacement amount Z of the sample 113. As shown in FIG. 3B, the detected light amount I is maximum when the surface of the sample 113 is at the in-focus position and decreases as the surface deviates from the in-focus position. On the other hand, the detection sensitivity of the displacement amount, which is the absolute value of the ratio ΔI / ΔZ of the change amount ΔI of the detected light amount I to the change amount ΔZ of the displacement amount Z, is minimum at the in-focus position and is low, approximately zero, even near the in-focus position. Therefore, in Example 1, the detection sensitivity is improved by using two confocal detectors.

[0023] Returning to FIG. 1 , the description of the measurement system will be continued. The probe light 501 irradiated onto the sample 113 is reflected by the surface of the sample 113, returns to the beam splitter 122 along the original optical path, and is reflected toward the condenser lens 124. The probe light 501 incident on the condenser lens 124 is focused and travels to the half mirror 125. At the half mirror 125, approximately half of the focused probe light 501 is transmitted toward the pinhole 126, and approximately the remaining half is reflected toward the pinhole 128. Of the probe light 501 transmitted through the half mirror 125, the probe light 501 that passes through the pinhole 126 is detected by the photodetector 127. Alternatively, of the probe light 501 reflected by the half mirror 125, the probe light 501 that passes through the pinhole 128 is detected by the photodetector 129. Note that the pinholes 126 and 128 are positioned away from the focal position of the condenser lens 124. That is, the pinhole 126 is positioned at a distance L from the focal position of the condenser lens 124 in a direction away from the sample 113, and the pinhole 128 is positioned at a distance L from the focal position in a direction approaching the sample 113. Note that the distance L is set to be equal to or less than the depth of focus, i.e., within the distance at which the image is in focus.

[0024] 4A is a graph showing the relationship between the amount of light detected by the photodetector 127 and the amount of displacement of the sample 113 when the pinholes 126 and 128 are positioned apart by a distance L. The peaks of the detected light amount curve PD1 of the photodetector 127 and the detected light amount curve PD2 of the photodetector 129 are shifted by the distance L from the in-focus position.

[0025] 4B is a graph obtained by adding the detected light intensity curves PD1 and PD2. By using the graph illustrated in FIG. 4B, the displacement amount can be measured at a position where the detection sensitivity of the displacement amount, which is the absolute value of ΔI / ΔZ, is high, for example, at the position indicated by a circle in FIG. 4B. In other words, if the area is within the focal depth, the detection sensitivity can be improved by measuring the displacement amount at a position away from the focal position.

[0026] Japanese Patent Application Laid-Open No. 2003-129999 describes that the position where the value calculated using the following equation becomes zero is determined as the in-focus position.

[0027] (PD2-PD1) / (PD2+PD1) (Equation 1) The value calculated by (Equation 1) changes approximately linearly with respect to the displacement amount Z, and ideally becomes zero at the focal position. That is, the above applies to an ideal sample 113 having an ultra-smooth surface. However, since the surface of an actual sample has irregularities, the amount of light measured at a position that is a distance L away from the focal position and that is closer to the sample is not the same as the amount of light measured at a position that is a distance L away.

[0028] Figure 5 is a schematic diagram showing how light incident on the sample surface is reflected at focal positions +L and -L. The area of ​​the sample surface onto which the incident light strikes is the same at both focal positions +L and -L, but the angle of incidence onto the sample differs at focal positions +L and -L, resulting in a different reflection angle of the reflected light. That is, at focal position +L, the reflected light is reflected in a direction that does not return to the detector, but at focal position -L, it is reflected in a direction that returns to the detector, resulting in a greater amount of light being detected in the latter case.

[0029] Therefore, in the present invention, instead of controlling the position of the sample 113 in the Z direction so that the value of (Equation 1) described in Patent Document 1 becomes zero, the position in the Z direction is controlled by using the position where the derivative of (Equation 1), {(PD2-PD1) / (PD2+PD1)}'... (Equation 2), becomes a peak as the focusing position.

[0030] FIG. 4C shows an example of a graph of (Equation 1) and (Equation 2). In the case of an ideal sample with a smooth surface, the position where the value of (Equation 1) is zero is the focal position. However, as mentioned above, most real samples do not have smooth surfaces, so the position where the value of (Equation 1) is zero is not necessarily the focal position. In such cases, the value of (Equation 1) varies depending on the surface roughness, etc., of the real sample, so it is unclear what value corresponds to the focal position, and the focal position cannot be determined.

[0031] In contrast, in Equation 2, the position where the value peaks is always the focal position, so the focal position can be determined even if the peak position shifts left or right on FIG. 4C due to the roughness of the sample surface. By controlling the position of the sample 113 in the Z direction, it is possible to absorb shifts in the focal position due to drift in the distance between the objective lens 111 and the sample 113, etc. Furthermore, it is possible to perform measurements while tracking the focal position relative to the unevenness of the surface of the sample 113. Furthermore, even if the reflectance or refractive index of the surface of the sample 113 is not uniform or if the intensity of the light source 120 fluctuates, these effects can be suppressed.

[0032] Although the calculation method using differentiation has been described above, instead of differentiation, the focus position can also be determined by performing frequency component analysis using a fast Fourier transform (FFT) or the like, locking in specific frequency components, performing a detection calculation, and finding their peak value.

[0033] Here, a further explanation will be given of the beam splitter 122. When the ratio of transmission to reflection in the beam splitter 122 is approximately 1:1, the amount of probe light 501 passing through the beam splitter 122 twice is reduced to 1 / 4. Therefore, in order to suppress the reduction in the amount of probe light 501, a polarizing beam splitter may be used as the beam splitter 122.

[0034] When a polarizing beam splitter is used, assuming that the light emitted from the collimator lens 121 is polarized in the vertical direction of the paper, most of the light passes through the beam splitter 122. When a λ / 4 plate whose axis is rotated 45 degrees relative to the polarization direction is used as the filter 123, the probe light 501 emitted from the filter 123 becomes circularly polarized. The circularly polarized probe light 501 is reflected by the surface of the sample 113, returns to the filter 123 along the original optical path, and passes through the λ / 4 plate, where it is converted from circularly polarized light to linearly polarized light perpendicular to the paper. Due to the characteristics of the polarizing beam splitter, almost all of the linearly polarized probe light 501 is reflected toward the condenser lens 124. In other words, by using a polarizing beam splitter as the beam splitter 122 and using a λ / 4 plate as the filter 123, the probe light 501 can be guided toward the photodetectors 127 and 129 without reducing the amount of light.

[0035] Furthermore, a wavelength filter that transmits only the wavelength of the probe light 501 may be added as the filter 123. By adding a wavelength filter, detection of light other than the probe light 501 is suppressed, and detection noise can be reduced.

[0036] The control system will be described. The control system is a control device 300 having an overall control unit 301, an energy source control unit 302, a lock-in detection unit 303, a probe light quantity correction unit 304, an energy intensity correction unit 305, a defocus amount calculation unit 306, and an XY scan control unit 307. The overall control unit 301 is a computing unit that controls each unit and processes and transmits data generated in each unit, such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). Each unit other than the overall control unit 301 may be configured with dedicated hardware using an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array), or may be configured with software running on a computing unit. The display device, printer, or storage device mentioned in the above and below descriptions may be part of the control device 300 or may be an external device.

[0037] The energy source control unit 302 controls the wavelength, intensity, etc. of the energy beam 500 generated by the energy source 100. By scanning the wavelength, the absorption spectrum of the sample 113 can be measured. Furthermore, by modulating the intensity, lock-in detection by the lock-in detection unit 303, which will be described later, becomes possible.

[0038] The lock-in detection unit 303 performs so-called lock-in detection by detecting the detected light intensities PD1 and PD2 of the photodetectors 127 and 129 while comparing them with the modulation signal transmitted from the energy source control unit 302. By performing lock-in detection on the signal of PD2-PD1, for example, using the modulation signal as a reference, the amplitude of PD2-PD1 can be found.

[0039] Note that lock-in detection may be performed for each of PD1 and PD2 using the modulated signal as a reference, and then the difference between the two may be calculated, or lock-in detection may be performed for the value of (Equation 1).

[0040] Instead of lock-in detection, so-called AM detection may be used, in which a displacement signal corresponding to the modulation frequency of the energy beam 500 is extracted using a filter and then the amplitude is measured. Alternatively, the displacement signal may be spectrally analyzed using FFT or the like, and the intensity of the spectral peak corresponding to the modulation frequency may be measured. Furthermore, other common amplitude detection methods may be used.

[0041] The probe light intensity correction unit 304 divides the amplitude of PD2-PD1 by PD2+PD1 obtained by the lock-in detection unit 303. The value obtained by this division is proportional to the amplitude of the displacement of the surface of the sample 113, and is therefore hereinafter referred to as a sample displacement measurement value.

[0042] The energy intensity correction unit 305 calculates a value proportional to the energy absorptance by dividing the sample displacement measurement value obtained by the probe light intensity correction unit 304 by the intensity of the energy beam 500 measured by the energy detector 104. The absorption spectrum of the sample 113 is obtained by calculating a value proportional to the energy absorptance while scanning the wavelength of the energy beam 500. The obtained absorption spectrum may be output to an external device in tabular or graphical form. For example, the graphical absorption spectrum may be displayed on a display device such as a liquid crystal display, stored in a storage device, or printed by a printer or the like. The defocus amount calculation unit 306 controls the Z-direction position of the objective lens 111 based on the value of (Equation 2). Controlling the Z-direction position of the objective lens 111 enables the probe light 501 to follow the irregularities on the surface of the sample 113.

[0043] The XY scan control unit 307 moves the objective lens 111 or the XY stage 112 in the X and Y directions. By moving the objective lens 111 or the XY stage 112, the energy beam 500 and the probe light 501 can be irradiated at any position on the sample 113, and the distribution of the absorption spectrum on the surface of the sample 113 can be measured. In particular, by performing measurements using the two confocal detectors while moving the objective lens 111 or the XY stage 112 with the wavelength of the energy beam 500 fixed, a map image of the absorbance for that wavelength can be generated.

[0044] The defocus amount calculation unit 306 and the XY scan control unit 307 work in cooperation with each other, so that the lens or the stage can be moved while the probe light 501 follows the focus of the probe light 501 relative to the unevenness of the surface of the sample 113. As a result, XY scan can be performed while always maintaining high detection sensitivity of the energy absorption rate. The generated absorbance map image may be output to an external device as an image or in graph form. For example, the map image may be displayed on a display device such as a liquid crystal display, stored in a storage device, or printed by a printer or the like. The graph display is a two-dimensional graph when one-dimensional scanning is performed by the XY scan control unit 307, and a three-dimensional graph when two-dimensional scanning is performed by the XY scan control unit 307.

[0045] As described above, in Example 1, changes in physical properties such as expansion of the sample 113 due to energy imparted by infrared rays or the like are detected based on the outputs PD1 and PD2 of the two confocal detectors, thereby improving detection sensitivity. Furthermore, a differential value of (PD2-PD1) / (PD2+PD1) is calculated from each output, thereby suppressing the effects of the reflectance and refractive index of the surface of the sample 113, surface irregularities, fluctuations in the light intensity of the energy beam 500 and the probe light 501, drift in the distance between the objective lens 111 and the sample 113, and the like. Furthermore, by using visible light, which has a shorter wavelength than infrared light, as the probe light 501, spatial resolution can be improved.

[0046] Furthermore, by using the outputs PD1 and PD2 of the two confocal detectors, autofocusing is possible in addition to measuring changes in physical properties, eliminating the need for a separate autofocus mechanism and realizing space-saving spectroscopic measurement equipment. Furthermore, autofocusing using two confocal detectors allows the focal position to be tracked quickly even on sample surfaces with large irregularities, thereby shortening the time required for measurement.

[0047] In the first embodiment, the objective lens 111 is moved in the X and Y directions to scan the position irradiated with the energy beam 500 and the probe light 501. In the second embodiment, the objective lens 111 is fixed while the position irradiated with the energy beam 500 and the probe light 501 is scanned. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted.

[0048] 6A and 6B, a description will be given of essential parts of Example 2. In the spectroscopic measurement apparatus of Example 2, an x-scanning mirror 115, a y-scanning mirror 116, and a Z-stage 114 are added to the configuration of Example 1.

[0049] The x-scanning mirror 115 and the y-scanning mirror 116 are mirrors that reflect the energy beam 500 and the probe light 501. The energy beam 500 and the probe light 501 are scanned in the X direction by the rotation of the x-scanning mirror 115, and scanned in the Y direction by the rotation of the y-scanning mirror 116. The rotation of the x-scanning mirror 115 and the y-scanning mirror 116 is controlled by an XY scan control unit 307.

[0050] The Z stage 114 is placed on the XY stage 112, and moves in the Z direction as the sample 113 is placed thereon. The movement of the Z stage 114 in the Z direction is controlled by the defocus amount calculation unit 306. That is, the position of the Z stage 114 in the Z direction is controlled based on the value of (Equation 1), so that the probe light 501 can follow the irregularities on the surface of the sample 113, as in the first embodiment.

[0051] 6A, an x-scanning mirror 115 and a y-scanning mirror 116 are disposed between a dichroic mirror 110 and an objective lens 111, and the rotation of these mirrors causes an energy beam 500 and a probe light 501 to scan the surface of a sample 113. By scanning the surface of the sample 113 with the energy beam 500 and the probe light 501, the distribution of the absorption spectrum can be measured, as in the first embodiment.

[0052] 6B, an x-scanning mirror 115 and a y-scanning mirror 116 are disposed between the filter 123 and the dichroic mirror 110, and the rotation of these mirrors causes only the probe light 501 to scan the surface of the sample 113. That is, in the configuration of FIG. 6B, even if the x-scanning mirror 115 and the y-scanning mirror 116 rotate, the energy beam 500 is not scanned. Note that the probe light 501 is scanned within the region irradiated with the energy beam 500. By scanning the probe light 501 within the region irradiated with the energy beam 500, the distribution of the absorption spectrum within the region can be measured.

[0053] As described above, in the second embodiment, at least the probe light 501 is scanned on the surface of the sample 113 by the rotation of the x-scanning mirror 115 and the y-scanning mirror 116, so that the distribution of the absorption spectrum can be measured. Furthermore, similar to the first embodiment, changes in physical properties such as thermal expansion of the sample 113 to which energy is imparted by infrared rays or the like are detected based on the outputs PD1 and PD2 of the two confocal detectors, so that the detection sensitivity can be improved.

[0054] Note that scanning of the probe light 501 and the energy beam 500 may be performed not only by rotation of the x-scanning mirror 115 and the y-scanning mirror 116, but also by a combination of horizontal movement of the XY stage 112 and the objective lens 111. For example, in the configuration of Fig. 6B, the probe light 501 may be aligned with the region to be irradiated with the energy beam 500 by rotation of the x-scanning mirror 115 and the y-scanning mirror 116, and then the surface of the sample 113 may be scanned by moving the objective lens 111, etc.

[0055] Furthermore, as in Example 1, by using the outputs PD1 and PD2 of the two confocal detectors, autofocusing is possible in addition to measuring changes in physical properties, eliminating the need for a separate autofocus mechanism and realizing space-saving spectroscopic measurement equipment. Furthermore, autofocusing using two confocal detectors allows the focal position to be tracked quickly even on sample surfaces with large irregularities, thereby shortening the time required for measurement.

[0056] In the first embodiment, it has been described that two confocal detectors are used to detect the probe light 501 reflected on the surface of the sample 113. In the third embodiment, it will be described that, in addition to detection by the confocal detectors, the probe light 501 before being focused by the condenser lens 124 is detected via an aperture to measure the scattering state on the surface of the sample 113. Note that the same components as those in the first embodiment are given the same reference numerals, and their description will be omitted.

[0057] The main parts of Example 3 will be described with reference to Figure 7. The spectroscopic measurement device of Example 3 adds a mirror 130, an aperture stop 131, and a photodetector 132 to the configuration of Example 1. The mirror 130 is disposed between the beam splitter 122 and the condenser lens 124, and reflects a part or almost all of the probe light 501 reflected on the surface of the sample 113 toward the aperture stop 131. That is, if the mirror 130 is a partial reflection mirror, a part of the probe light 501 is directed toward the aperture stop 131, and if the mirror 130 is a total reflection mirror, almost all of the probe light 501 is directed toward the aperture stop 131. The photodetector 132 detects the probe light 501 that has passed through the aperture stop 131, thereby measuring the scattering state of the surface of the sample 113.

[0058] The surface of the sample 113 irradiated with the energy beam 500 experiences local changes in curvature due to thermal expansion, and local changes in refractive index due to changes in temperature and carrier concentration. As a result, the scattering state of the surface of the sample 113 changes, which may cause a change in the angular distribution of the reflected light of the probe light 501. The change in the angular distribution of the reflected light changes the degree of spread of the probe light 501 at the aperture stop 131, which changes the amount of light detected by the photodetector 132. Therefore, the scattering state of the surface of the sample 113 can be measured by detecting the probe light 501 via the aperture stop 131 with the photodetector 132.

[0059] If the displacement of the surface of the sample 113 is small and difficult to detect, lock-in detection may be performed using the intensity of the energy beam 500 as a reference signal. If the mirror 130 is a total reflection mirror, measurement may be performed by a confocal detector when the mirror 130 is removed from the optical path of the probe light 501, and the scattering state may be measured when the mirror 130 is inserted into the optical path.

[0060] As described above, in the third embodiment, the probe light 501 before being focused by the condenser lens 124 is detected via the aperture stop 131, so that it is possible to measure the scattering state on the surface of the sample 113. Furthermore, it is possible to combine the measurement using the confocal detector with the measurement of the scattering state.

[0061] In the first embodiment, an infrared beam is used as the energy beam 500 that imparts energy to the sample 113. In the fourth embodiment, a charged particle beam such as an electron beam or an ion beam is used as the energy beam 500. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted.

[0062] 8A and 8B, the main parts of Example 4 will be described. In the spectroscopic measurement device of Example 4, a charged particle beam is used as the energy beam 500, and therefore the dichroic mirror 110 and the objective lens 111 cannot be shared between the energy deposition system and the measurement system. Therefore, in Figure 8A, the dichroic mirror 110 of Example 1 is replaced with a holey mirror 110', and the objective lens 111 is replaced with a hollow objective lens 111'.

[0063] The perforated mirror 110' is a mirror with a hole in its center, and the hollow objective lens 111' is a lens with a hole in its center. An energy beam 500, which is a charged particle beam, passes through the holes in the perforated mirror 110' and the hollow objective lens 111' and is irradiated onto the sample 113. Furthermore, a probe beam 501 is reflected toward the hollow objective lens 111' at a location other than the hole in the perforated mirror 110', and is focused at a location other than the hole in the hollow objective lens 111' to be irradiated onto the sample 113. The probe beam 501, which is irradiated onto the sample 113 together with the energy beam 500, which is a charged particle beam, is reflected by the sample 113 and then detected by two confocal detectors, as in the first embodiment.

[0064] In FIG. 8B , the dichroic mirror 110 in the configuration of Example 1 is replaced with a mirror 110″. The probe light 501 is reflected by the mirror 110″ and enters the objective lens 111, where it is focused and irradiated onto the sample 113. In addition, the energy beam 500, which is a charged particle beam, is irradiated onto the sample 113 from off-axis of the objective lens 111. In the configuration of FIG. 8B as well, the probe light 501, which is irradiated onto the sample 113 together with the energy beam 500, which is a charged particle beam, is reflected by the sample 113 and then detected by two confocal detectors.

[0065] As described above, in the fourth embodiment, a charged particle beam is used as the energy beam 500, so that energy can be applied to a narrower area than with an infrared beam, thereby further improving spatial resolution. Note that an infrared beam can also be used as the energy beam 500 in the fourth embodiment instead of the charged particle beam.

[0066] The present invention has been described above in relation to several embodiments. However, the present invention is not limited to these embodiments, and the components may be modified or the embodiments may be combined as appropriate without departing from the spirit of the invention. Furthermore, some components may be omitted from all the components shown in the above embodiments.

[0067] 100: energy source, 101, 102: beam expander lens, 103: partial reflection mirror, 104: energy detector, 110: dichroic mirror, 110': holed mirror, 110'': mirror, 111: objective lens, 111': hollow objective lens, 112: XY stage, 113: sample, 114: Z stage, 115: x scanning mirror, 116: y scanning mirror, 120: light source, 121: collimator lens, 122: beam splitter, 123 : filter, 124: condensing lens, 125: half mirror, 126, 128: pinhole, 127, 129: photodetector, 130: mirror, 131: aperture stop, 132: photodetector, 300: control device, 301: overall control unit, 302: energy source control unit, 303: lock-in detection unit, 304: probe light quantity correction unit, 305: energy intensity correction unit, 306: focus deviation calculation unit, 307: XY scanning control unit, 500: energy beam, 501: probe light

Claims

1. A spectroscopic measurement device comprising: an electromagnetic wave source which generates electromagnetic waves to be irradiated onto a specified area of ​​a sample; an objective lens which focuses the electromagnetic waves onto the specified area; two confocal detectors arranged at different positions which detect the electromagnetic waves reflected by the sample; and a focus position discrimination mechanism which performs a differential calculation or a lock-in detection calculation of a signal obtained by dividing the difference signal and the sum signal of each output of the two confocal detectors, and discriminates the position at which the peak value is obtained as the focus position.

2. A spectroscopic measuring device as described in claim 1, further comprising a Z-direction control unit which controls the relative distance between the stage on which the sample is placed and the objective lens based on the result of the determination by the focus position determination mechanism.

3. A spectroscopic measurement device as claimed in claim 2, wherein the two confocal detectors comprise a first confocal detector having a pinhole positioned a distance L away from the focal position in a direction away from the sample, and a second confocal detector having a pinhole positioned a distance L away from the focal position in a direction towards the sample, and wherein the focus position determination mechanism, when the output of the first confocal detector is PD1 and the output of the second confocal detector is PD2, further performs a differential calculation or a lock-in detection calculation on the value of (PD2-PD1) / (PD2+PD1), and determines the position at which the peak value is obtained as the focus position.

4. A spectroscopic measuring device as described in claim 1, further comprising a calculation unit which calculates the change in the physical property value of the sample when the electromagnetic wave is irradiated onto the specified area based on the outputs of the confocal detector.

5. A spectroscopic measuring device according to claim 4, further comprising an electromagnetic wave intensity detector for measuring the intensity of the electromagnetic wave, and characterized in that the change in the physical property value is corrected based on the intensity of the electromagnetic wave.

6. A spectroscopic measuring device according to claim 4, characterized in that the electromagnetic wave source modulates the intensity of the electromagnetic wave, and the calculation unit corrects the change in the physical property value based on the modulated signal of the intensity of the electromagnetic wave.

7. The spectrometer according to claim 4, further comprising a display device for displaying the absorption spectrum.

8. The spectrometer according to claim 4, further comprising a display device for displaying a map image of absorbance.

9. A spectroscopic measuring device according to claim 1, further comprising an XY scanning control unit for controlling the position of said predetermined area.

10. A spectroscopic measuring device according to claim 9, characterized in that the XY scanning control unit controls the position of the specified area by horizontally moving the objective lens or a stage on which the sample is placed.

11. A spectroscopic measuring device as described in claim 9, wherein the XY scanning control unit is arranged on the path of the electromagnetic wave and controls the position of the specified area by rotating a mirror that reflects the electromagnetic wave.

12. A spectroscopic measurement method comprising the steps of: irradiating a predetermined area of ​​a sample with electromagnetic waves; acquiring the outputs of two confocal detectors provided at different positions which detect the electromagnetic waves reflected from the sample in response to the irradiation of the electromagnetic waves; and subjecting a signal obtained by dividing a difference signal and a sum signal of the outputs to a differential calculation or a lock-in detection calculation, and determining that the position at which the peak value is obtained is the focused position.

13. A spectroscopic measurement method according to claim 12, characterized in that it includes a step of calculating a change in a physical property value of the sample when the electromagnetic wave is irradiated onto the specified area based on each output of the confocal detector.

14. The spectroscopic measurement method according to claim 13, characterized in that the change in the physical property value is corrected based on the intensity of the electromagnetic wave reflected from the sample.

15. A spectroscopic measurement method as claimed in claim 14, characterized in that the intensity of the electromagnetic wave irradiated to a specified area of ​​the sample is modulated, and the change in the physical property value is corrected based on the modulated signal of the intensity of the electromagnetic wave.

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