Spectrometry device and spectrometry method

Abstract

To provide a spectrometry device that makes it possible to improve detection sensitivity to changes in physical properties such as expansion of a sample provided with energy by infrared radiation or the like, while also achieving high resolution and accurate autofocus.SOLUTION: A spectrometry device includes: an electromagnetic wave source for generating an electromagnetic wave to be emitted to a predetermined region of a sample; an objective lens for collecting an electromagnetic wave to the predetermined region; two shared focal point detectors for detecting an electromagnetic wave reflected by the sample; and a focus position determination mechanism for performing differential calculation or lock-in detection calculation on a signal obtained by dividing the difference signal and the sum signal of the outputs of each of the two shared focal point detectors and determining, as in-focus position, a position at which the peak value is obtained.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] A spectroscopic measurement device is a device that analyzes the composition of a substance or identifies foreign substances mixed in the substance by measuring the absorption curve unique to the substance with respect to the wavelength of light, that is, the absorption spectrum. For the analysis of molecular vibrations and the like, infrared rays, which are wavelengths around 10 times that of visible light, are generally used. Therefore, the spatial resolution limited by the diffraction limit proportional to the wavelength of the light used remains on the order of 10 μm.

[0003] In order to improve the resolution, Patent Document 1 discloses a spectroscopic measurement device provided with two confocal detectors for detecting electromagnetic waves reflected by a sample, and calculating changes in the physical properties of the sample when an energy beam is irradiated on a predetermined region based on each output of the confocal detectors.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent Document 1 describes that "autofocus is also possible by providing two confocal detectors", and as a method thereof, it is described that adjustment is made so that the value of (PD2 - PD1) / (PD2 + PD1) becomes zero (paragraph

[0025] ). When the inventors conducted a follow-up experiment, they found that there is a possibility that the point where the above formula becomes 0 is not necessarily the in-focus position. Figure 4 of Patent Document 1 assumes that PD1 and PD2 are completely symmetric. This premise holds for a sample with a mirror-like surface, but in general, actual samples usually have irregularities on the surface, and it is less likely that PD1 and PD2 are completely symmetric. Therefore, the inventors found that in many cases, the point where the value of (PD2 - PD1) / (PD2 + PD1) becomes zero is not the in-focus position.

[0006] The present invention was made while considering an improvement to the autofocus method described in Patent Document 1, and its object is to provide a spectroscopic measurement apparatus and a spectroscopic measurement method that have high resolution and enable accurate autofocus.

Means for Solving the Problem

[0007] The configuration of the present invention for achieving the above object is as follows. An electromagnetic wave source that generates electromagnetic waves for irradiating a predetermined region of a sample, an objective lens that focuses the electromagnetic waves on the predetermined region, two confocal detectors that detect the electromagnetic waves reflected by the sample, a focusing position determination mechanism that performs differential calculation or lock-in detection calculation on a signal obtained by dividing the difference signal and the sum signal of the outputs of the two confocal detectors, and determines the position where the peak value is taken as the in-focus position, and a spectroscopic measurement apparatus.

[0008] Further, a step of irradiating a predetermined region of a sample with electromagnetic waves, a step of obtaining each output 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 a step of performing differential calculation or lock-in detection calculation on a signal obtained by dividing the difference signal and the sum signal of the outputs, and determining the position where the peak value is taken as the in-focus position, and a spectroscopic measurement method.

Effect of the Invention

[0009] According to the present invention, it is possible to provide a spectroscopic measurement apparatus and a spectroscopic measurement method that have high resolution and enable accurate autofocus.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 4C

Figure 5

Figure 6A

Figure 6B

Figure 7

Figure 8A

Figure 8B

Modes for Carrying Out the Invention

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

Embodiment

[0012] The overall configuration of the spectroscopic measurement apparatus of Example 1 will be described with reference to FIG. 1. Note that the device configuration as the 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 this application.

[0013] The vertical direction in FIG. 1 is defined as the Z direction, and the horizontal directions are defined as the X direction and the Y direction. The spectroscopic measurement apparatus includes a stage mechanism system on which the sample 113 is installed, an energy application system that applies energy to the sample 113, a measurement system that measures the physical property values of the sample 113, and a control system that processes the data output from each part and controls each part.

[0014] The stage mechanism system has an XY stage 112 on which the sample 113 is installed and which moves in the X direction and the Y direction. By moving the XY stage 112 in the X direction and the Y direction, an arbitrary region on the surface of the sample 113 is analyzed.

[0015] The energy application system includes an energy source 100, beam expander lenses 101, 102, a partial reflection mirror 103, an energy detector 104, a dichroic mirror 110, and an objective lens 111. Note that the dichroic mirror 110 and the objective lens 111 are shared with the measurement system.

[0016] The energy source 100 generates an energy beam 500, such as an infrared beam, which imparts energy to the sample 113. The energy beam 500 is expanded in beam diameter by beam expander lenses 101, 102 and then travels towards the partial reflection mirror 103. The partial reflection mirror 103 transmits a part of the energy beam 500 towards the energy detector 104 and reflects the remainder towards the sample 113. The energy detector 104 measures the intensity of the energy beam 500 that has passed through the partial reflection mirror 103. The energy beam 500 reflected by the partial reflection mirror 103 passes through the dichroic mirror 110, is focused by the objective lens 111, and then irradiates the sample 113. The sample 113 irradiated with the energy beam 500 absorbs the imparted energy and causes a change in 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, 128, photodetectors 127, 129, a dichroic mirror 110, and an objective lens 111. In this embodiment, it is referred to as a "light source", but technically, since the electromagnetic wave to be irradiated can be other than "light" and still achieve the effects of the present invention, it is more accurate to use the term "electromagnetic wave source". Also, for the "condenser lens", "photodetector", etc., they should technically be referred to as "electromagnetic wave focusing lens", "electromagnetic wave detector", etc., but "light" is used for the sake of clarity of the text.

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

[0019] The energy beam 500 and the probe light 501 that irradiate 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. Since the probe light 501 has a smaller beam diameter than the energy beam 500 and is irradiated onto a region narrower than the region irradiated by the energy beam 500, changes in the physical property values of the region irradiated by the energy beam 500 can be measured 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 about 0.5 μm. Furthermore, by using a confocal detector in the measurement system, the spatial resolution of the measurement system becomes about 0.3 μm. The changes in the physical property values to be measured include changes in the displacement and curvature of the surface of the sample 113 that expands by absorbing the energy beam 500, changes in the surface refractive index and reflectivity, and the like.

[0020] The confocal detector will be described with reference to FIGS. 3A and 3B. The confocal detector is configured such that when the light irradiated from a point light source forms a focus on the surface of the sample, the light reflected from the sample forms a focus on the detection surface. 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 FIG. 3A. The probe light 501 emitted from the point light source of the light source 120 is made into a parallel beam by the collimator lens 121, then reflected by the beam splitter 122 and incident on the objective lens 111. The objective lens 111 focuses the probe light 501 to form a focus.

[0021] When the focus coincides with 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 solid-line optical path in FIG. 3A and forms a focus 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 the irradiation of 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 dotted-line optical path and does not form a focus at the pinhole 126. As a result, the amount of light detected by the photodetector 127 passing through the pinhole 126 decreases compared to the case of the solid-line optical path. That is, since the amount of detected light of the photodetector 127 changes according to the displacement amount of the surface of the sample 113, the change in the physical property value of the sample 113 to which energy is applied can be measured by the photodetector 127.

[0022] FIG. 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 it 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 also low, almost zero, in the vicinity of 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 on the sample 113 is reflected on the surface of the sample 113, returns to the beam splitter 122 in 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 proceeds 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 the remaining approximately half is reflected toward the pinhole 128. Among the probe light 501 transmitted through the half mirror 125, the probe light 501 that has passed through the pinhole 126 is detected by the photodetector 127. Also, among the probe light 501 reflected by the half mirror 125, the probe light 501 that has passed through the pinhole 128 is detected by the photodetector 129. Note that the pinhole 126 and the pinhole 128 are arranged outside the focal position of the condenser lens 124. That is, the pinhole 126 is arranged 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 arranged at a distance L from the focal position in a direction approaching the sample 113. Note that the distance L is set to be below the depth of focus, that is, within the distance at which the focus is achieved.

[0024] FIG. 4A is a graph showing the relationship between the detected light amounts of the photodetector 127 and the photodetector 129 and the displacement amount of the sample 113 when the pinhole 126 and the pinhole 128 are arranged at a distance L apart. 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 a distance L from the in-focus position.

[0025] FIG. 4B is a graph obtained by adding the detected light amount 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 absolute value of ΔI / ΔZ is high, for example, at the position indicated by a circle in FIG. 4B. That is, within the region of the depth of focus, the detection sensitivity can be improved by measuring the displacement amount at a position deviated from the focal position.

[0026] Patent Document 1 describes that the position at which the value calculated using the following formula becomes zero is set 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 in-focus position. That is, for an ideal sample with a super-smooth surface of the sample 113, it is as described above. However, since the surface of an actual sample has irregularities, the amount of light measured at a position closer to the sample by a distance L from the focus position and the amount of light measured at a position farther by a distance L are not the same.

[0028] FIG. 5 is a schematic diagram showing how the light incident on the sample surface is reflected at the in-focus position +L and the in-focus position -L. The area where the incident light hits the sample surface is the same for both the in-focus position +L and the in-focus position -L, but since the incident angles to the sample are different at the in-focus position +L and the in-focus position -L, the reflection angles of the reflected light are different. That is, in the case of the in-focus position +L, the reflected light is reflected in a direction where it does not return to the detector, but in the case of the in-focus position -L, it is reflected in a direction that returns to the detector, so the amount of light detected is larger 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 {(PD2 - PD1) / (PD2 + PD1)}'… (Equation 2) is differentiated, and the position in the Z direction is controlled with the position where it peaks as the in-focus position.

[0030] FIG. 4C illustrates graphs 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) becomes zero is the in-focus position. However, as described above, in most cases, the surface of an actual sample is not smooth, so the position where the value of (Equation 1) is zero does not necessarily become the in-focus position. In that case, since the value of (Equation 1) changes depending on the surface roughness of the actual sample, etc., it may be unclear what value it is for the in-focus position, and the in-focus position cannot be determined.

[0031] In contrast, in (Equation 2), since the position where the value peaks is always the focal position, even if the peak position shifts left and right on FIG. 4C due to the roughness of the sample surface, the focal position can be determined. By controlling the position of the sample 113 in the Z direction, it is possible to absorb the shift of the focal position due to drift or the like of the distance between the objective lens 111 and the sample 113. Further, it is possible to perform measurement while following the focal position with respect to the unevenness of the surface of the sample 113. Furthermore, even when the reflectivity or refractive index of the surface of the sample 113 is not uniform or when the intensity of the light source 120 fluctuates, the influence thereof can be suppressed.

[0032] Note that in the above, the calculation method by differentiation has been described. Instead of differentiation, the focal position can also be determined by performing frequency component analysis by fast Fourier transform (FFT) or the like, locking in and detecting a specific frequency component, and obtaining the peak value thereof.

[0033] Here, an explanation will be added about the beam splitter 122. When the transmission and reflection in the beam splitter 122 are approximately 1 to 1, the amount of the probe light 501 that passes through the beam splitter 122 twice decreases to 1 / 4. Therefore, in order to suppress the decrease in the amount of the probe light 501, a polarization 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 and horizontal directions of the paper surface, most of the light passes through the beam splitter 122. When a λ / 4 plate rotated 45 degrees in the axial direction with respect to the polarization direction is arranged as the filter 123, the probe light 501 emitted from the filter 123 becomes circularly polarized. The circularly polarized probe light 501 is reflected from the surface of the sample 113, returns to the filter 123 in the original optical path, and is converted from circular polarization to linearly polarized light in a direction perpendicular to the paper surface by passing through the filter 123 which is a λ / 4 plate. Further, the probe light 501 converted to linearly polarized light is almost entirely reflected toward the condenser lens 124 due to the characteristics of the polarizing beam splitter. That is, by using a polarizing beam splitter as the beam splitter 122 and arranging a λ / 4 plate as the filter 123, it is possible to guide the light toward the photodetectors 127 and 129 without reducing the amount of the probe light 501.

[0035] In addition, as the filter 123, a wavelength filter that transmits only the wavelength of the probe light 501 may be added. By adding the 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 focus deviation amount calculation unit 306, and an XY scanning control unit 307. The overall control unit 301 is an arithmetic unit that controls each unit and processes and transmits data generated by each unit. For example, it is a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or the like. Each unit other than the overall control unit 301 may be composed of dedicated hardware using an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or the like, or may be composed of software operating on an arithmetic unit. Note that the display device, printer, or storage device that appears in the foregoing and subsequent descriptions may be a part of the control device 300 or 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. Also, by modulating the intensity, lock-in detection by the lock-in detection unit 303 described later becomes possible.

[0038] The lock-in detection unit 303 performs so-called lock-in detection by detecting the detected light quantities 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, for example, the signal of PD2 - PD1 with the modulation signal as a reference, the amplitude of PD2 - PD1 can be obtained.

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

[0040] Alternatively, 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 by a filter and then the amplitude is measured. Also, the displacement signal may be subjected to spectral analysis using FFT or the like, and the intensity of the spectral peak corresponding to the modulation frequency may be measured. Furthermore, other general amplitude detection methods may be used.

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

[0042] The energy intensity correction unit 305 calculates a value proportional to the energy absorption rate by dividing the sample displacement measurement value obtained by the probe light quantity correction unit 304 by the intensity of the energy beam 500 measured by the energy detector 104. By calculating the value proportional to the energy absorption rate while scanning the wavelength of the energy beam 500, the absorption spectrum of the sample 113 is obtained. The obtained absorption spectrum may be output to the outside in a table format or a graph format. For example, the absorption spectrum in graph format 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. Note that the focus shift amount calculation unit 306 controls the position of the objective lens 111 in the Z direction based on the value of (Equation 2). By controlling the position of the objective lens 111 in the Z direction, it becomes possible for the probe light 501 to follow the unevenness of the surface of the sample 113.

[0043] The XY scanning 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 onto any position of the sample 113, and the distribution of the absorption spectrum on the surface of the sample 113 can be measured. In particular, while fixing the wavelength of the energy beam 500, by moving the objective lens 111 or the XY stage 112 and performing measurements with two confocal detectors, a map image of the absorbance for the wavelength can be generated.

[0044] Note that the focus deviation amount calculation unit 306 and the XY scanning control unit 307 operate in cooperation to move the lens or the stage while performing focus tracking of the probe light 501 with respect to the unevenness of the surface of the sample 113. As a result, it becomes possible to perform XY scanning while always maintaining a state with high detection sensitivity of the energy absorption rate. Also, the generated map image of the absorbance may be output to the outside as an image or in a graph format. 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 format display is, for example, a two-dimensional graph when performing one-dimensional scanning by the XY scanning control unit 307, and a three-dimensional graph when performing two-dimensional scanning by the XY scanning control unit 307.

[0045] As described above, in the first embodiment, based on the outputs PD1 and PD2 of the two confocal detectors, changes in physical property values such as the expansion of the sample 113 to which energy is applied by infrared rays or the like are detected, so that the detection sensitivity can be improved. Also, since the differential value of (PD2 - PD1) / (PD2 + PD1) is calculated from each output, effects such as the reflectivity and refractive index of the surface of the sample 113, the unevenness of the surface, fluctuations in the light amounts of the energy beam 500 and the probe light 501, and drifts in the distance between the objective lens 111 and the sample 113 can be suppressed. Furthermore, by using visible light, which has a shorter wavelength than infrared rays, as the probe light 501, the spatial resolution can be improved.

[0046] Furthermore, by using the outputs PD1 and PD2 of the two confocal detectors, autofocus is possible in addition to measuring changes in physical property values, eliminating the need for a separate autofocus mechanism and enabling space savings in the spectroscopic measurement apparatus. Also, autofocus using the two confocal detectors allows the focal position to rapidly follow the surface of a sample with large irregularities, reducing the measurement time.

Example

[0047] In Example 1, it was described that the position irradiated with the energy beam 500 and the probe light 501 is scanned by moving the objective lens 111 in the X and Y directions. In Example 2, with the objective lens 111 fixed, the position irradiated with the energy beam 500 and the probe light 501 will be described. The same components as in Example 1 are denoted by the same reference numerals and the description thereof is omitted.

[0048] The main part of Example 2 will be described with reference to FIGS. 6A and 6B. The spectroscopic measurement apparatus of Example 2 has an x-scanning mirror 115, a y-scanning mirror 116, and a Z stage 114 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 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 the XY scanning control unit 307.

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

[0051] In FIG. 6A, an x-scanning mirror 115 and a y-scanning mirror 116 are disposed between a dichroic mirror 110 and an objective lens 111. By rotating both mirrors, an energy beam 500 and a probe light 501 are scanned on the surface of a sample 113. By scanning the energy beam 500 and the probe light 501 on the surface of the sample 113, the distribution of the absorption spectrum can be measured in the same manner as in the first embodiment.

[0052] In FIG. 6B, an x-scanning mirror 115 and a y-scanning mirror 116 are disposed between a filter 123 and a dichroic mirror 110. By rotating both mirrors, only the probe light 501 is scanned on the surface of the sample 113. That is, in the configuration of FIG. 6B, the energy beam 500 is not scanned even when the x-scanning mirror 115 and the y-scanning mirror 116 rotate. 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. Also, as in the first embodiment, based on the outputs PD1 and PD2 of the two confocal detectors, changes in physical property values such as the thermal expansion of the sample 113 to which energy is applied by infrared rays or the like are detected, so that the detection sensitivity can be improved.

[0054] The scanning of the probe light 501 and the energy beam 500 may be performed not only by the rotation of the x-scanning mirror 115 and the y-scanning mirror 116 but also in combination with the horizontal movement of an XY stage 112 or the objective lens 111. For example, in the configuration of FIG. 6B, after aligning the position of the probe light 501 with respect to the region irradiated with the energy beam 500 by the rotation of the x-scanning mirror 115 and the y-scanning mirror 116, the surface of the sample 113 may be scanned by moving the objective lens 111 or the like.

[0055] Furthermore, similar to Example 1, by using the outputs PD1 and PD2 of the two confocal detectors, autofocus is possible in addition to measuring changes in physical property values, eliminating the need for a separate autofocus mechanism and enabling space savings in the spectroscopic measurement device. Also, with autofocus using two confocal detectors, the focal position can be rapidly tracked with respect to the surface of a sample with large unevenness, shortening the measurement time.

Example

[0056] In Example 1, the detection of the probe light 501 reflected from the surface of the sample 113 using two confocal detectors was described. In Example 3, the measurement of the scattering state of the surface of the sample 113 by detecting the probe light 501 before being focused by the condenser lens 124 through an aperture in addition to the detection by the confocal detector will be described. Note that the same components as those in Example 1 are denoted by the same reference numerals and the description thereof is omitted.

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

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

[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. Also, when the mirror 130 is a total reflection mirror, it may be measured 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 Example 3, since the probe light 501 before being focused by the condenser lens 124 is detected through the aperture stop 131, the scattering state of the surface of the sample 113 can be measured. Also, the measurement by the confocal detector and the measurement of the scattering state can be combined.

Example

[0061] In Example 1, the use of an infrared beam as the energy beam 500 for applying energy to the sample 113 was described. In Example 4, the use of a charged particle beam such as an electron beam or an ion beam as the energy beam 500 will be described. Note that the same components as those in Example 1 are denoted by the same reference numerals and the description thereof is omitted.

[0062] Using FIGS. 8A and 8B, the main part of Example 4 will be described. In the spectroscopic measurement apparatus of Example 4, since a charged particle beam is used as the energy beam 500, the dichroic mirror 110 and the objective lens 111 cannot be shared in the energy application system and the measurement system. Therefore, in FIG. 8A, with respect to the configuration of Example 1, the dichroic mirror 110 is replaced by a perforated mirror 110', and the objective lens 111 is replaced by a hollow objective lens 111'.

[0063] The perforated mirror 110' is a mirror having a hole in the center, and the hollow objective lens 111' is a lens having a hole in the center. The energy beam 500, which is a charged particle beam, passes through the holes of the perforated mirror 110' and the hollow objective lens 111' and irradiates the sample 113. Also, the probe light 501 is reflected toward the hollow objective lens 111' at a location other than the hole of the perforated mirror 110', is focused at a location other than the hole of the hollow objective lens 111', and irradiates the sample 113. The probe light 501 irradiated onto the sample 113 together with the energy beam 500, which is a charged particle beam, is detected by two confocal detectors after being reflected by the sample 113, in the same manner as in Example 1.

[0064] In FIG. 8B, with respect to the configuration of Example 1, the dichroic mirror 110 is replaced by a mirror 110''. The probe light 501 is reflected by the mirror 110'' and enters the objective lens 111, is focused, and irradiates the sample 113. Also, the energy beam 500, which is a charged particle beam, is irradiated onto the sample 113 from off-axis of the objective lens 111. Also in the configuration of FIG. 8B, the probe light 501 irradiated onto the sample 113 together with the energy beam 500, which is a charged particle beam, is detected by two confocal detectors after being reflected by the sample 113.

[0065] As described above, in Example 4, since a charged particle beam is used as the energy beam 500, energy can be applied to a region narrower than an infrared beam, and the spatial resolution can be further improved. Note that an infrared beam can also be used as the energy beam 500 in Example 4 instead of a charged particle beam.

[0066] As described above, a plurality of embodiments of the present invention have been described. The present invention is not limited to these embodiments, and components may be modified or the embodiments may be appropriately combined without departing from the gist of the invention. Furthermore, some components may be deleted from all the components shown in the above embodiments.

Description of Reference Numerals

[0067] 100: Energy source, 101, 102: Beam expander lenses, 103: Partial reflection mirror, 104: Energy detector, 110: Dichroic mirror, 110': Perforated 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 amount calculation unit, 307: XY scanning control unit, 500: Energy beam, 501: Probe light.

Claims

1. An electromagnetic wave source that generates electromagnetic waves to irradiate a predetermined region of a sample, an objective lens that focuses the electromagnetic waves on the predetermined region, two confocal detectors provided at different positions that detect the electromagnetic waves reflected by the sample, a focusing position discrimination 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 discriminates the position where the peak value is obtained as the focusing position, A spectroscopic measurement device characterized by comprising the above.

2. In the spectroscopic measurement device according to Claim 1, A spectroscopic measurement device characterized by comprising a Z-direction control unit that controls the relative distance between the stage on which the sample is placed and the objective lens based on the discrimination result of the focusing position discrimination mechanism.

3. In the spectroscopic measurement device according to Claim 2, The two confocal detectors include a first confocal detector having a pinhole disposed at a distance L from the focal position in a direction away from the sample, and a second confocal detector having a pinhole disposed at a distance L from the focal position in a direction approaching the sample, When the output of the first confocal detector is PD1 and the output of the second confocal detector is PD2 in the focusing position discrimination mechanism, the value of (PD2 - PD1) / (PD2 + PD1) is further subjected to differential calculation or lock-in detection calculation, and the position where the peak value is obtained is discriminated as the focusing position. A spectroscopic measurement device characterized by the above.

4. In the spectroscopic measurement device according to Claim 1, A spectroscopic measurement device characterized by comprising a calculation unit that calculates a change in a physical property value of the sample when the electromagnetic waves are irradiated on the predetermined region based on each output of the confocal detector.

5. In the spectroscopic measurement device according to Claim 4, Comprising an electromagnetic wave intensity detector that measures the intensity of the electromagnetic waves, A spectroscopic measurement device characterized by correcting the change in the physical property value based on the intensity of the electromagnetic waves.

6. In the spectroscopic measurement device according to Claim 4, The electromagnetic wave source modulates the intensity of the electromagnetic waves, The calculation unit corrects the change in the physical property value based on the modulation signal of the intensity of the electromagnetic waves. A spectroscopic measurement device characterized by the above.

7. In the spectroscopic measurement device according to Claim 4, A spectroscopic measurement device characterized by comprising a display device that displays an absorption spectrum.

8. In the spectroscopic measurement device according to Claim 4, A spectroscopic measurement device characterized by comprising a display device that displays a map image of absorbance.

9. In the spectroscopic measurement apparatus according to claim 1, A spectroscopic measurement apparatus, comprising an XY scanning control unit for controlling the position of the predetermined region.

10. In the spectroscopic measurement apparatus according to claim 9, The spectroscopic measurement apparatus, wherein the XY scanning control unit controls the position of the predetermined region by horizontally moving the objective lens or the stage on which the sample is placed.

11. In the spectroscopic measurement apparatus according to claim 9, The spectroscopic measurement apparatus, wherein the XY scanning control unit controls the position of the predetermined region by rotating a mirror disposed on the path of the electromagnetic wave and reflecting the electromagnetic wave.

12. Irradiating a predetermined region of a sample with an electromagnetic wave; Obtaining outputs of two confocal detectors provided at different positions for detecting the electromagnetic wave reflected from the sample due to the irradiation of the electromagnetic wave; Calculating a differential or lock-in detection of a signal obtained by dividing the difference signal and the sum signal of the respective outputs, and determining a position where a peak value is taken as a focusing position; A spectroscopic measurement method, comprising the steps of:

13. In the spectroscopic measurement method according to claim 12, The spectroscopic measurement method, further comprising calculating a change in a physical property value of the sample when the predetermined region is irradiated with the electromagnetic wave based on each output of the confocal detector.

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

15. In the spectroscopic measurement method according to claim 14, Modulating the intensity of the electromagnetic wave irradiated on a predetermined region of the sample; The spectroscopic measurement method, wherein the change in the physical property value is corrected with reference to a modulation signal of the intensity of the electromagnetic wave.

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