Inspection apparatus and inspection method

Abstract

The invention provides an inspection device and an inspection method, which can observe both photoluminescence light and Raman scattering light with a simple structure and can highly evaluate crystals. An inspection apparatus according to an embodiment includes: a pulsed light generation unit that generates pulsed light having a wavelength longer than a wavelength of light corresponding to a band gap of a sample, the pulsed light causing the sample to perform multiphoton excitation; a condensing unit including an objective lens, condensing the pulsed light onto the sample using the objective lens, and transmitting light including photoluminescence light (PL) and Raman scattering light (RS) generated from the sample by irradiation of the pulsed light through the objective lens; a first detection means for detecting the photoluminescence light (PL) that has passed through the objective lens; and a second detection means that detects Raman scattering light (RS) that has passed through the objective lens.

Description

Technical Field

[0001] The invention relates to an inspection device and an inspection method. Background Art

[0002] By using conventional photoluminescence measurement using photoluminescent light, it is possible to observe polymorphism and internal defects of crystal degeneration in semiconductor wafers. However, in conventional photoluminescence measurement, it is difficult to see stress distribution without crystal degeneration, such as residual processing stress. Such residual stress may become the starting point of modification or destruction into defects in subsequent epitaxial processes or thermal processes. Therefore, it is preferable to be able to evaluate stress inside the crystal.

[0003] For such evaluation, Raman spectroscopy using Raman scattered light is effective. Therefore, an inspection device based on photoluminescence measurement and combined with Raman spectroscopy is desired. However, in the case of conventional photoluminescence measurement, band-end emission is generated at a wavelength very close to the excitation light. Therefore, if Raman spectroscopy is performed using the excitation light of the photoluminescence measurement, there are problems such as the band-end emission covering the Raman scattered light, which is a weak signal. Therefore, in order to combine Raman spectroscopy measurement, it is necessary to take countermeasures such as using a light source with a different wavelength from the light source used for the photoluminescence measurement.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2003-194718.

[0007] Problem that the invention aims to solve

[0008] For example, Patent Document 1 discloses, as a method for detecting internal defects of a sample containing a wide bandgap semiconductor represented by gallium nitride (GaN) or the like, multiphoton excitation photoluminescence measurement in which laser light having a wavelength longer than the wavelength of light corresponding to the bandgap is focused on the sample and photoluminescence light generated by multiphoton excitation is detected. In addition, Patent Document 1 discloses that internal lattice vibrations are detected by further combining multiphoton excitation photoluminescence measurement with Raman spectroscopy measurement. However, Patent Document 1 does not disclose that the excitation light for multiphoton excitation photoluminescence measurement and the excitation light for Raman spectroscopy measurement use the same wavelength, nor does it disclose a specific structure.

[0009] There is a demand for an inspection apparatus and an inspection method that can detect both photoluminescence light and Raman scattered light with a simple configuration using a light source for multiphoton excitation photoluminescence measurement, thereby enabling advanced crystal evaluation. Summary of the invention

[0010] The present invention has been made in view of such problems, and provides an inspection device and an inspection method capable of observing both photoluminescence light and Raman scattered light with a simple structure, thereby enabling advanced crystal evaluation.

[0011] Solutions for solving problems

[0012] One method of the present embodiment involves an inspection device comprising: a pulse light generating unit, which generates pulse light having a wavelength longer than a wavelength of light corresponding to a band gap of a sample, wherein the pulse light causes multi-photon excitation of the sample; a focusing unit, which includes an objective lens, which uses the objective lens to focus the pulse light onto the sample, and allows light including photoluminescence light and Raman scattered light generated from the sample by irradiation with the pulse light to pass through the objective lens; a first detection unit, which detects the photoluminescence light that has passed through the objective lens; and a second detection unit, which detects the Raman scattered light that has passed through the objective lens.

[0013] In the above inspection apparatus, the sample may include a semiconductor wafer.

[0014] In the above-mentioned inspection device, the focusing unit may also include: a semi-reflective mirror, which is arranged between the objective lens and the second detection unit on the optical path of the pulse light, and the semi-reflective mirror transmits any one of the pulse light and the Raman scattered light and reflects the other; a first pinhole, which is arranged between the semi-reflective mirror and the pulse light generating unit; and a second pinhole, which is arranged between the second detection unit and the semi-reflective mirror, and at least the second detection unit detects the Raman scattered light generated from the part of the sample on which the pulse light is focused.

[0015] In the above inspection device, the half mirror may reflect the pulse light and transmit the Raman scattered light and the photoluminescent light, or transmit the pulse light and reflect the Raman scattered light and the photoluminescent light.

[0016] In the above inspection device, the light focusing unit may further include a dichroic mirror disposed between the half mirror and the first and second detection units, the dichroic mirror transmitting either one of the photoluminescence light and the Raman scattered light and reflecting the other.

[0017] In the above inspection device, the dichroic mirror can reflect or transmit the central wavelength of the pulse light and light in a wavelength range of ±100 nm at its periphery, and guide the light in the wavelength range to the second detection unit.

[0018] In the above-mentioned inspection device, the focusing unit may further include a first filter arranged between the dichroic mirror and the first detection unit, the first filter including at least any one of a short-pass filter that transmits short-wavelength light below 400 nm, a long-pass filter that transmits light with a wavelength longer than 700 nm, and a band-pass filter that transmits light greater than 400 nm and below 700 nm, and the first detection unit detects the photoluminescence light that has passed through the first filter.

[0019] In the above-mentioned inspection device, the focusing unit may further include a second filter arranged between the dichroic mirror and the second detection unit, the second filter including a filter that blocks at least the light of the central wavelength of the pulse light, and the second detection unit detects the Raman scattered light that has passed through the second filter.

[0020] In the above inspection apparatus, the second optical filter may include an optical filter that blocks light below a central wavelength of the pulse light or light above a central wavelength of the pulse light.

[0021] In the above inspection device, the wavelength of the pulse light may include a wavelength in the visible light region.

[0022] One method of the present embodiment relates to an inspection method comprising: a pulse light generating step, in which a pulse light generating unit generates pulse light having a wavelength longer than a wavelength of light corresponding to a band gap of a sample, wherein the pulse light causes multi-photon excitation of the sample; a focusing step, in which an objective lens is used to focus the pulse light onto the sample, and light including photoluminescence light and Raman scattered light generated from the sample by irradiation with the pulse light is transmitted through the objective lens; and a detection step, in which a first detection unit detects the photoluminescence light transmitted through the objective lens, and a second detection unit detects the Raman scattered light transmitted through the objective lens.

[0023] In the above inspection method, the sample may include a semiconductor wafer.

[0024] In the above inspection method, in the focusing step, a half-reflection mirror arranged between the objective lens and the second detection unit on the optical path of the pulse light can be used to transmit either the pulse light or the Raman scattered light and reflect the other, and a first pinhole arranged between the half-reflection mirror and the pulse light generating unit and a second pinhole arranged between the second detection unit and the half-reflection mirror can be used to enable at least the second detection unit to detect the Raman scattered light generated from the part of the sample on which the pulse light is focused.

[0025] In the above inspection method, the half mirror may reflect the pulse light and transmit the Raman scattered light and the photoluminescent light, or transmit the pulse light and reflect the Raman scattered light and the photoluminescent light.

[0026] In the inspection method, in the light focusing step, a dichroic mirror disposed between the half mirror and the first and second detection units may be used to transmit one of the photoluminescence light and the Raman scattered light and reflect the other.

[0027] In the above inspection method, the dichroic mirror may reflect or transmit the central wavelength of the pulse light and light in a wavelength range of ±100 nm at its periphery, and guide the light in the wavelength range to the second detection unit.

[0028] In the above inspection method, in the focusing step, the first filter arranged between the dichroic mirror and the first detection unit may include at least any one of a short-pass filter that transmits light of a short wavelength below 400 nm, a long-pass filter that transmits light of a wavelength longer than 700 nm, and a band-pass filter that transmits light of a wavelength greater than 400 nm and below 700 nm, so that the first detection unit detects the photoluminescence light that has passed through the first filter.

[0029] In the above inspection method, in the focusing step, the second filter arranged between the dichroic mirror and the second detection unit may include a filter that blocks at least light of the center wavelength of the pulse light, so that the second detection unit detects the Raman scattered light that has passed through the second filter.

[0030] In the above inspection method, the second optical filter may further include an optical filter that blocks light below a central wavelength of the pulse light or light above a central wavelength of the pulse light.

[0031] In the above inspection method, the wavelength of the pulse light may include a wavelength in the visible light region.

[0032] Effects of the Invention

[0033] According to the present invention, it is possible to provide an inspection device and an inspection method capable of detecting both photoluminescence light and Raman scattered light with a simple structure, thereby enabling advanced crystal evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a diagram illustrating the configuration of the inspection device according to the first embodiment.

[0035] Figure 2 This is a flowchart illustrating the inspection method according to the first embodiment.

[0036] Figure 3 This is a diagram illustrating the structure of an inspection device according to the second embodiment.

[0037] Figure 4 This is a diagram illustrating the configuration of an inspection device according to the third embodiment.

[0038] Figure 5 This is a graph illustrating the transmission characteristics of the dichroic mirror in the inspection device according to the third embodiment, where the horizontal axis represents the wavelength and the vertical axis represents the transmittance.

[0039] Figure 6 This is a graph illustrating the characteristics of the optical filter in the inspection device according to the third embodiment, where the horizontal axis represents the wavelength and the vertical axis represents the transmittance.

[0040] Figure 7 This is a graph illustrating light detected by the first detection unit and the second detection unit in the inspection device according to the third embodiment, where the horizontal axis represents the wavelength and the vertical axis represents the transmittance.

[0041] Figure 8 This is a graph illustrating light detected by the first detection unit and the second detection unit in the inspection device according to the third embodiment, where the horizontal axis represents the wavelength and the vertical axis represents the transmittance.

[0042] Fig. 9 This is a graph illustrating light detected by the first detection unit and the second detection unit in the inspection device according to the third embodiment, where the horizontal axis represents the wavelength and the vertical axis represents the transmittance. DETAILED DESCRIPTION

[0043] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following description shows preferred embodiments of the present invention, and the scope of the present invention is not limited to the following embodiments. In the following description, parts marked with the same reference numerals represent substantially the same contents.

[0044] (Implementation Method 1)

[0045] The inspection device and the inspection method according to the first embodiment will be described. Figure 1 1 is a block diagram illustrating an inspection device 1 according to Embodiment 1. Figure 1As shown, the inspection device 1 of this embodiment includes a pulse light generating unit 10, a focusing unit 20, and a detection unit 30. The inspection device 1 irradiates the sample 40 with a pulse light 11 having a wavelength longer than the wavelength of light corresponding to the band gap of the sample 40 such as a semiconductor wafer. Thus, the inspection device 1 observes the photoluminescence light PL generated by multiphoton excitation caused by the pulse light 11 and the Raman scattered light RS caused by the pulse light 11. In the figure, only the optical axes of the pulse light 11, the photoluminescence light PL, and the Raman scattered light RS are schematically shown. The sample 40 includes, for example, a semiconductor wafer using a semiconductor as a material. Specifically, the semiconductor material can include a wide band gap compound semiconductor such as silicon carbide (SiC) and GaN. However, the sample 40 is not limited to a semiconductor wafer as long as it includes a crystal having a band gap.

[0046] The pulse light generating unit 10 generates a pulse light 11 having a wavelength longer than the wavelength of light corresponding to the band gap of the sample 40. The pulse light generating unit 10 generates the pulse light 11 for causing the sample 40 to undergo multiphoton excitation.

[0047] In the case of ordinary photoluminescence measurement, light having energy greater than the band gap energy of the sample 40 is irradiated to the sample 40. Thus, photoluminescence light PL emitted when the sample 40 transitions from an excited state to a ground state is measured.

[0048] On the other hand, in the case of photoluminescence measurement based on multiphoton excitation, light of 1 / 2, 1 / 3 or 1 / 4 or less of the band gap energy of the sample 40 is irradiated to the sample 40. Then, the photoluminescence light PL emitted when the sample 40 is transferred from the state of being excited by 2-photon, 3-photon or 4-photon or more multiphotons to the ground state is measured. In this way, in the case of photoluminescence measurement based on multiphoton excitation, a pulse light 11 having a wavelength longer than the wavelength of light corresponding to the band gap of the sample 40 is used. The pulse light generating unit 10 is preferably a femtosecond laser or the like that can generate the pulse light 11 with high output power. In addition, the pulse light generating unit 10 is not limited to a femtosecond laser.

[0049] The specifications of the pulse light 11 may be, for example, infrared light having a central wavelength of 1040 nm and an output power of 3 W. In this case, for a sample 40 such as SiC and GaN, light PL based on photoluminescence excited by 3 photons can be generated. In addition, the specifications of the pulse light 11 may be, for example, visible light having a central wavelength of 520 nm and an output power of 1 W. In this case, for a sample 40 such as SiC and GaN, light PL based on photoluminescence excited by 2 photons can be generated. As such, the wavelength of the pulse light 11 may include wavelengths in the infrared light region, and may also include wavelengths in the visible light region.

[0050] The focusing unit 20 includes an objective lens 21. In addition to the objective lens 21, the focusing unit 20 may also include other optical components such as a half mirror 22. The focusing unit 20 focuses the pulse light 11 toward the sample 40 using the objective lens 21. In addition, the focusing unit 20 allows the light 41 generated from the sample 40 by the irradiation of the pulse light 11 to pass through the objective lens 21. Thus, the focusing unit 20 guides the light 41 generated from the sample 40 to the detection unit 30. The light 41 generated from the sample 40 includes photoluminescence light PL and Raman scattered light RS. In the figure, the light 41 including the photoluminescence light PL and the Raman scattered light RS is represented as 41 (PL, RS).

[0051] The detection unit 30 includes a first detection unit 31 and a second detection unit 32. The first detection unit 31 detects the photoluminescence light PL that has passed through the objective lens 21. The first detection unit 31 includes a detector capable of detecting the photoluminescence light PL, such as a CCD (Charge Coupled Device) sensor, a TDI (Time Delay Integration) camera, a PMT (Photomultiplier Tube), etc. The second detection unit 32 detects the Raman scattered light RS that has passed through the objective lens 21. The second detection unit 32 includes a detector capable of detecting the Raman scattered light RS, such as a CCD, a PMT, etc. The second detection unit 32 may also include a spectrometer.

[0052] The first detection unit 31 and the second detection unit 32 in the detection unit 30 may be integrally configured. For example, the detection unit 30 may have the functions of the first detection unit 31 and the second detection unit 32, and detect the photoluminescence light PL and the Raman scattered light RS at the same time. In addition, the detection unit 30 may also detect the photoluminescence light PL and the Raman scattered light RS by switching the first detection unit 31 and the second detection unit 32 through the switching unit.

[0053] Figure 2 is a flowchart illustrating the inspection method of embodiment 1. Figure 2 As shown, the inspection method of this embodiment includes a pulse light generating step S11 , a light focusing step S12 , and a detection step S13 .

[0054] In the pulse light generation step S11 , first, the pulse light 11 is generated to perform multiphoton excitation on the sample 40 . For example, the pulse light generation unit 10 generates the pulse light 11 having a wavelength longer than the wavelength of light corresponding to the band gap of the sample 40 .

[0055] Next, in the focusing step S12, the pulse light 11 is focused toward the sample 40 using the objective lens 21. At the same time, light 41 generated from the sample 40 by irradiation with the pulse light 11 is transmitted through the objective lens 21. The light 41 includes photoluminescence light PL and Raman scattered light RS.

[0056] Next, in the detection step S13, the photoluminescence light PL transmitted through the objective lens 21 is detected by the first detection unit 31. Furthermore, the Raman scattered light RS transmitted through the objective lens 21 is detected by the second detection unit 32.

[0057] Next, the effect of this embodiment is described. This embodiment performs multi-photon excitation of the sample 40 by irradiating the sample 40 with pulse light 11 having a wavelength longer than the wavelength of light corresponding to the band gap of the sample 40. Thus, both the photoluminescence light PL and the Raman scattered light RS are detected. By photoluminescence measurement, crystal defects of the sample 40 can be detected. By Raman spectrum measurement, deformation and stress inside the sample 40 can be detected. Therefore, this embodiment is not limited to detecting crystal defects of the sample 40, and can detect various internal abnormalities including deformation and stress.

[0058] In addition, in this embodiment, by observing the photoluminescence light PL through multiphoton excitation of long-wavelength light, the Raman scattered light RS, which is difficult to measure in the usual photoluminescence measurement using short-wavelength light, is measured simultaneously. As a result, the Raman scattered light RS generated at the generation site of the photoluminescence light PL can be correlated. Therefore, both the photoluminescence light PL and the Raman scattered light RS can be detected using a simple structure, and the crystal evaluation can be advanced.

[0059] Even if the Raman spectroscopy measurement is combined with the conventional photoluminescence measurement, and the Raman scattered light RS is detected while the photoluminescence light PL is detected, it is difficult to detect the Raman scattered light RS with an effective resolution because the wavelength bands of the photoluminescence light PL and the Raman scattered light RS are roughly the same and the weaker Raman scattered light RS is covered. In addition, in compound semiconductors such as SiC, since ultraviolet light is used as the excitation light for conventional photoluminescence measurement, the range of the detector for detecting the Raman scattered light RS for ultraviolet light is very narrow, and the operation is very difficult.

[0060] In contrast, in this embodiment, the Raman spectroscopy measurement is combined with the photoluminescence measurement using multiphoton excitation as a basis. Furthermore, when the photoluminescence measurement using multiphoton excitation is performed, light with a wavelength from the visible light region to the infrared light region is used as the excitation light. This can solve the above-mentioned problem.

[0061] In addition, since a laser light source having a high output power required for multi-photon excitation is used for the pulse light generating unit 10, it is possible to detect weak Raman scattered light RS with a sufficient intensity and a good S / N ratio. Thus, it is possible to observe Raman scattered light RS that can evaluate stress inside the crystal. For example, the Stokes shift in Raman spectrum measurement can be indicated by depth, and a reference Stokes wave number can be determined and the intensity ratio of the wave number can be displayed. The stress inside the sample 40 can be detected based on the intensity of the Stokes shift.

[0062] (Implementation Method 2)

[0063] Next, the inspection device according to Embodiment 2 will be described. In the inspection device according to this embodiment, the focusing unit 20 includes a confocal optical system. Figure 3 2 is a block diagram illustrating an inspection device according to Embodiment 2. Figure 3 As shown, in the inspection device 2 of this embodiment, the focusing unit 20 includes a half mirror 22, a first aperture 23, and a second aperture 24 in addition to the objective lens 21. In addition, the focusing unit 20 may include other optical components in addition to the above components.

[0064] The half mirror 22 is disposed between the objective lens 21 and the second detection unit 32 on the optical path of the pulse light 11. The half mirror 22 transmits either the pulse light 11 or the Raman scattered light RS, and reflects the other. Figure 3 In the inspection device 2 shown, the half mirror 22 reflects the pulse light 11 and transmits the light 41 including the Raman scattered light RS. In this case, the half mirror 22 also transmits the light 41 including the photoluminescence light PL. In addition, the positions of the pulse light generating unit 10 and the detection unit 30 relative to the objective lens 21 may be exchanged, and the half mirror 22 transmits the pulse light 11 and reflects the light 41 including the Raman scattered light RS. In this case, the half mirror 22 also reflects the light 41 including the photoluminescence light PL.

[0065] The first pinhole 23 is arranged between the half mirror 22 and the pulse light generating unit 10. The second pinhole 24 is arranged between the second detecting unit 32 and the half mirror 22. The first pinhole 23 and the second pinhole 24 are arranged in a manner to form a confocal optical system. That is, at least the second detecting unit 32 detects the Raman scattered light RS generated from the portion where the pulse light 11 of the sample 40 is focused.

[0066] In the inspection method of this embodiment, in the focusing step S12, one of the pulse light 11 and the Raman scattered light RS is transmitted and the other is reflected by the half mirror 22 disposed between the objective lens 21 and the second detection unit 32 on the optical path of the pulse light 11. The first pinhole 23 disposed between the half mirror 22 and the pulse light generating unit 10 and the second pinhole 24 disposed between the second detection unit 32 and the half mirror 22 allow at least the second detection unit 32 to detect the Raman scattered light RS generated from the portion of the sample 40 on which the pulse light 11 is focused.

[0067] According to the present embodiment, the focusing unit 20 forms a confocal optical system. Therefore, the second detection unit 32 detects the Raman scattered light RS generated from the portion where the pulse light 11 of the sample 40 is focused, so that the intensity of the Raman scattered light RS can be increased. In addition, since multi-photon excitation requiring the energy of multiple photons is generated in the region where the pulse light is focused, the first detection unit 31 detects the photoluminescence light PL generated from the portion where the pulse light 11 of the sample 40 is focused. As a result, the photoluminescence light PL and the Raman scattered light RS can be correlated with higher accuracy, and the crystal evaluation of the sample 40 can be improved.

[0068] (Implementation 3)

[0069] Next, description will be given of an inspection device and an inspection method according to Embodiment 3. The inspection device of this embodiment separates photoluminescence light PL from Raman scattered light RS by a dichroic mirror. Figure 4 2 is a block diagram illustrating an inspection device according to Embodiment 3. Figure 4 As shown, the focusing unit 20 of the inspection device 3 of this embodiment further includes a dichroic mirror 25. In addition, the focusing unit 20 may further include a filter 27 and a filter 28. In addition, the focusing unit 20 may further include other optical components such as a reflector 26 in addition to the above optical components.

[0070] The dichroic mirror 25 is disposed between the half mirror 22 and the first and second detection units 31 and 32. The dichroic mirror 25 transmits one of the photoluminescence light PL and the Raman scattered light RS, and reflects the other.

[0071] Figure 5 2 is a graph illustrating the transmission characteristics of the dichroic mirror 25 in the inspection device 3 of the third embodiment, wherein the horizontal axis represents the wavelength and the vertical axis represents the transmittance. Figure 5As shown, the dichroic mirror 25 reflects or transmits light in a wavelength range near the central wavelength of the pulse light 11, and guides the light 41 in the wavelength range to the second detection unit 32. The light 41 in the wavelength range includes Raman scattered light RS in addition to the pulse light 11. The wavelength range is, for example, ±100 nm of the central wavelength of the pulse light 11. In addition, the wavelength range may also be, for example, ±50 nm of the central wavelength of the pulse light 11.

[0072] As an example, Figure 4 As shown, the dichroic mirror 25 reflects light 41 in the wavelength range including the Raman scattered light RS, and transmits light 41 including the photoluminescent light PL other than the Raman scattered light RS. The light 41 in the wavelength range including the Raman scattered light RS reflected by the dichroic mirror 25 transmits the second pinhole 24. The second pinhole 24 is arranged between the dichroic mirror 25 and the second detection unit 32. The light 41 that has transmitted the second pinhole 24 is reflected by the reflector 26 and enters the optical filter 28. The optical filter 28 is arranged between the dichroic mirror 25 and the second detection unit 32.

[0073] Figure 6 2 is a graph illustrating the characteristics of the optical filter 28 in the inspection device 3 of the third embodiment, wherein the horizontal axis represents the wavelength and the vertical axis represents the transmittance. Figure 6 As shown, the filter 28 includes a filter that blocks at least the light of the center wavelength of the pulse light 11 for extracting the Raman shift. The filter 28 may include an edge filter, for example. Specifically, the filter 28 includes a filter that blocks light below the center wavelength of the pulse light 11 or above the center wavelength of the pulse light 11. In addition, it is desired that the second detection unit 32 detects the Stokes scattering with high intensity in the Raman scattered light RS. Therefore, the filter 28 is preferably a filter with a long-pass characteristic that blocks light 41 below the center wavelength of the pulse light 11 and with a transmission wavelength longer than the center wavelength. In this way, the second detection unit 32 detects the Raman scattered light RS that has passed through the filter 28. In addition, the filter 28 may also have a switching unit that switches multiple filters. The switching unit switches the filter according to the wavelength of the observed Raman scattered light RS.

[0074] like Figure 4 As shown, light 41 including the photoluminescence light PL that has passed through the dichroic mirror 25 enters the optical filter 27. The optical filter 27 is arranged between the dichroic mirror 25 and the first detection unit 31. The optical filter 27 includes at least one of a short-pass filter that transmits short-wavelength light of 400 nm or less, a long-pass filter that transmits light with a wavelength longer than 700 nm, and a band-pass filter that transmits light greater than 400 nm and less than 700 nm. In addition, the optical filter 27 may also include a switching unit that switches a plurality of filters. The switching unit switches the filter according to the wavelength of the photoluminescence light PL to be observed.

[0075] Figure 7 to Figure 9 : is a graph illustrating the wavelength band of the light 41 detected by the first detection unit 31 and the second detection unit 32 in the inspection device 3 of the third embodiment, wherein the horizontal axis represents the wavelength and the vertical axis represents the transmittance, and shows the intensity of the light 41 detected by the first detection unit 31 and the second detection unit 32. Figure 7 As shown, the first detection unit 31 can detect the light 41 that has passed through a short-pass filter that transmits light of a short wavelength of 400 nm or less. In this case, the band-edge emission of SiC or the like can be observed.

[0076] In addition, if Figure 8 As shown, the first detection unit 31 can also detect light 41 that has passed through a long pass filter that transmits light with a wavelength longer than 700 nm. In this case, the photoluminescence light PL from the basal plane dislocation (BPD) known as a fatal defect existing in semiconductor materials such as SiC can be observed.

[0077] Furthermore, if Fig. 9 As shown, the first detection unit 31 can also detect the light 41 that has passed through the bandpass filter that transmits light greater than 400nm and less than 700nm. In this case, the photoluminescence light PL of impurity luminescence, defect level luminescence, and stacking fault luminescence of wide-bandgap semiconductors such as SiC can be observed. In this way, the first detection unit 31 detects the photoluminescence light PL that has passed through the filter 27.

[0078] In the inspection method of this embodiment, in the focusing step S12, one of the photoluminescence light PL and the Raman scattered light RS is transmitted by the dichroic mirror 25, and the other is reflected. In addition, the first detection unit 31 detects the photoluminescence light PL that has passed through the filter 27. In addition, the second detection unit 32 detects the Raman scattered light RS that has passed through the filter 28.

[0079] According to the present embodiment, the optical path of the photoluminescence light PL detected by the first detection unit 31 and the optical path of the Raman scattered light RS detected by the second detection unit 32 can be separated by the dichroic mirror 25. Therefore, the optical path of the Raman scattered light RS can be formed by the confocal optical system, and the optical path of the photoluminescence light PL is not formed by the confocal optical system.

[0080] In the photoluminescence measurement of multi-photon excitation, the probability that the photoluminescence light PL is generated from the portion where the pulse light is focused, that is, the portion where the photon density is high is high. Therefore, the first detection unit 31 detects the photoluminescence light PL generated from the portion where the pulse light 11 is focused. Therefore, even if there is no confocal optical system such as the second pinhole 24, the first detection unit 31 can substantially detect the photoluminescence light PL generated from the portion where the pulse light 11 is focused.

[0081] On the other hand, in this embodiment, the second detection unit 32 detects Raman scattered light RS generated from the focused portion of the pulse light 11 using a confocal optical system. This allows accurate correlation between the photoluminescence light PL and the Raman scattered light RS, and enables advanced crystal evaluation of the sample 40.

[0082] In this embodiment, the optical path of the photoluminescence light PL does not need to be constituted by a confocal optical system, so that optical components can be reduced.

[0083] Since the optical path of the photoluminescence light PL and the optical path of the Raman scattered light RS can be separated, different filters 27 and 28 corresponding to the detection target can be arranged on each optical path. Therefore, the desired wavelength regions can be detected for the photoluminescence light PL and the Raman scattered light RS.

[0084] It is desirable that the sizes of the first pinhole 23 and the second pinhole 24 are variable. By changing the sizes of the first pinhole 23 and the second pinhole 24, the size of the portion on which the pulse light 11 in the sample 40 is focused can be changed. Therefore, the size of the observation range of the sample 40 can be changed. For example, by changing the sizes of the first pinhole 23 and the second pinhole 24 corresponding to the observation range, the photoluminescence light PL and the Raman scattered light RS can be correlated with higher accuracy, wherein the observation range depends on the generation probability of the photoluminescence light PL generated by multi-photon excitation. In addition, although an example in which the optical path of the photoluminescence light PL is not constituted by a confocal optical system is described, the optical path of the photoluminescence light PL can also be constituted by a confocal optical system in the same manner as the optical path of the Raman scattered light RS.

[0085] Although the embodiments of the present invention have been described above, the present invention includes appropriate modifications that do not impair the objects and advantages thereof and is not limited to the above embodiments. In addition, a combination of the configurations of Embodiments 1 to 3 is also within the scope of the technical concept of the present invention.

[0086] Description of Reference Numerals

[0087] 1, 2, 3: Check the device

[0088] 10: Pulse light generation unit

[0089] 11: Pulse Light

[0090] 20: Focusing unit

[0091] 21: Objective lens

[0092] 22: Half mirror

[0093] 23: First small hole

[0094] 24: Second small hole

[0095] 25: Dichroic Mirror

[0096] 26: Reflector

[0097] 27: Filter

[0098] 28: Filter

[0099] 30: Detection unit

[0100] 31: First detection unit

[0101] 32: Second detection unit

[0102] 40: Sample

[0103] 41: Light

[0104] PL: Photoluminescence light

[0105] RS: Raman scattered light

Claims

1. An inspection device, comprising: a pulse light generating unit that generates pulse light having a wavelength longer than the wavelength of light corresponding to the band gap of the sample, wherein the pulse light causes the sample to undergo multi-photon excitation; a light focusing unit including an objective lens, which focuses the pulse light toward the sample using the objective lens and allows light including photoluminescence light and Raman scattered light generated from the sample by irradiation with the pulse light to pass through the objective lens; a first detection unit, which detects the photoluminescence light transmitted through the objective lens; as well as A second detection unit detects the Raman scattered light that has passed through the objective lens.

2. The inspection device according to claim 1, wherein: The sample includes a semiconductor wafer.

3. The inspection device according to claim 1 or 2, wherein: The light focusing unit further comprises: a half mirror disposed between the objective lens and the second detection unit on the optical path of the pulse light, the half mirror transmitting either the pulse light or the Raman scattered light and reflecting the other; A first small hole is arranged between the semi-reflective mirror and the pulse light generating unit; and A second small hole is arranged between the second detection unit and the half-reflecting mirror, At least the second detection unit detects the Raman scattered light generated from the portion of the sample on which the pulse light is focused.

4. The inspection device according to claim 3, wherein: The half mirror reflects the pulse light and transmits the Raman scattered light and the photoluminescent light, or transmits the pulse light and reflects the Raman scattered light and the photoluminescent light.

5. The inspection device according to claim 4, wherein: The focusing unit further includes a dichroic mirror disposed between the semi-reflective mirror and the first detection unit and the second detection unit. The dichroic mirror transmits one of the photoluminescence light and the Raman scattered light, and reflects the other.

6. The inspection device according to claim 5, wherein: The dichroic mirror reflects or transmits the central wavelength of the pulse light and light in a wavelength range of ±100 nm at its widest point around it, and guides the light in the wavelength range to the second detection unit.

7. The inspection device according to claim 5, wherein: The light focusing unit further includes a first filter disposed between the dichroic mirror and the first detection unit. The first optical filter includes at least one of a short-pass filter that transmits light of a short wavelength of 400 nm or less, a long-pass filter that transmits light of a wavelength longer than 700 nm, and a band-pass filter that transmits light of a wavelength greater than 400 nm and less than 700 nm. The first detection unit detects the photoluminescence light that has passed through the first filter.

8. The inspection device according to claim 5, wherein: The light focusing unit further includes a second filter disposed between the dichroic mirror and the second detection unit. The second optical filter includes an optical filter that blocks at least light of a central wavelength of the pulse light, The second detection unit detects the Raman scattered light that has passed through the second optical filter.

9. The inspection device according to claim 8, wherein: The second optical filter includes an optical filter that blocks light below a central wavelength of the pulse light or light above a central wavelength of the pulse light.

10. The inspection device according to claim 1 or 2, wherein: The wavelength of the pulse light includes a wavelength in the visible light region.

11. An inspection method, comprising: a pulse light generating step, causing a pulse light generating unit to generate pulse light having a wavelength longer than a wavelength of light corresponding to a band gap of the sample, wherein the pulse light causes multi-photon excitation of the sample; a focusing step of focusing the pulse light toward the sample using an objective lens, and allowing light including photoluminescence light and Raman scattered light generated from the sample by irradiation with the pulse light to pass through the objective lens; as well as The detection step causes the first detection unit to detect the photoluminescence light transmitted through the objective lens, and causes the second detection unit to detect the Raman scattered light transmitted through the objective lens.

12. The inspection method according to claim 11, wherein: The sample includes a semiconductor wafer.

13. The inspection method according to claim 11 or 12, wherein: In the light focusing step, Through a half mirror disposed between the objective lens and the second detection unit on the optical path of the pulse light, one of the pulse light and the Raman scattered light is transmitted, and the other is reflected. By configuring a first pinhole between the semi-reflective mirror and the pulse light generating unit and a second pinhole between the second detecting unit and the semi-reflective mirror, at least the second detecting unit detects the Raman scattered light generated from the portion of the sample on which the pulse light is focused.

14. The inspection method according to claim 13, wherein: The half mirror reflects the pulse light and transmits the Raman scattered light and the photoluminescent light, or transmits the pulse light and reflects the Raman scattered light and the photoluminescent light.

15. The inspection method according to claim 14, wherein: In the light focusing step, The dichroic mirror disposed between the half mirror and the first and second detection units allows one of the photoluminescence light and the Raman scattered light to be transmitted and the other to be reflected.

16. The inspection method according to claim 15, wherein: The dichroic mirror reflects or transmits the central wavelength of the pulse light and the light in the widest wavelength range of ±100 nm around it, and guides the light in the wavelength range to the second detection unit.

17. The inspection method according to claim 15, wherein: In the light focusing step, The first filter arranged between the dichroic mirror and the first detection unit includes at least any one of a short-pass filter that transmits light of a short wavelength below 400 nm, a long-pass filter that transmits light of a wavelength longer than 700 nm, and a band-pass filter that transmits light of a wavelength greater than 400 nm and below 700 nm, so that the first detection unit detects the photoluminescence light that has passed through the first filter.

18. The inspection method according to claim 15, wherein: In the light focusing step, The second optical filter disposed between the dichroic mirror and the second detection unit includes a filter that blocks at least light of a central wavelength of the pulse light, so that the second detection unit detects the Raman scattered light that has passed through the second optical filter.

19. The inspection method according to claim 18, wherein: The second optical filter also includes an optical filter that blocks light below a central wavelength of the pulse light or light above a central wavelength of the pulse light.

20. The inspection method according to claim 11 or 12, wherein: The wavelength of the pulse light includes a wavelength in the visible light region.

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