Inspection equipment and inspection method

Abstract

To provide an inspection device and an inspection method capable of observing both of photoluminescence light and Raman scattering light by a simple configuration and advancing crystal evaluation.SOLUTION: An inspection device 1 includes: pulse light generation means 10 for generating pulse light 11 that has a longer wavelength than a wavelength of light corresponding to a bandgap of a sample 40 and performs multiphoton excitation of the sample 40; condensing means 20 including an objective lens 21, condenses the pulse light 11 by the objective lens 21 for the sample 40, and transmitting light 41 including photoluminescence light PL and Raman scattering light RS generated from the sample 40 by application of the pulse light 11 through the objective lens 21; first detection means 31 for detecting the photoluminescence light PL through the objective lens 21; and second detection means 32 for detecting the Raman scattering light RS through the objective lens 21.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an inspection apparatus and an inspection method.

Background Art

[0002] By general photoluminescence measurement using photoluminescence light, it is possible to observe polytype and internal defects in which the crystal of a semiconductor wafer has deteriorated. However, in general photoluminescence measurement, it is difficult to observe a stress distribution that does not involve crystal deterioration, such as processing stress residues. Such stress residues may become a starting point for transformation into defects or destruction in subsequent epitaxial processes or thermal processes. Therefore, it is preferable to be able to evaluate the internal stress of the crystal.

[0003] For such an evaluation, Raman spectrum measurement using Raman scattered light is effective. Therefore, an inspection apparatus that combines Raman spectrum measurement based on photoluminescence measurement is desired. However, when based on general photoluminescence measurement, band-edge emission occurs at wavelengths very close to the excitation light. Therefore, when performing Raman spectrum measurement using the excitation light of photoluminescence measurement, there are problems such as the band-edge emission covering the Raman scattered light, which is a weak signal. Therefore, in order to combine Raman spectrum measurement, it is necessary to take measures such as using a light source having a wavelength different from that of the light source for photoluminescence measurement.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] For example, Patent Document 1 discloses a method for detecting internal defects in a sample containing a wide-bandgap semiconductor, such as gallium nitride (GaN), by focusing laser light with a wavelength longer than the wavelength of light corresponding to the bandgap onto the sample and detecting photoluminescence light due to multiphoton excitation. Furthermore, Patent Document 1 discloses the detection of internal lattice vibrations by combining multiphoton excitation photoluminescence measurement with Raman spectroscopy. However, Patent Document 1 does not disclose using the same wavelength for the excitation light used in multiphoton excitation photoluminescence measurement and the excitation light used in Raman spectroscopy measurement, nor does it disclose a specific configuration.

[0006] There is a need for an inspection device and inspection method that can detect both photoluminescent light and Raman scattered light in a simple configuration using a light source used for multiphoton-excited photoluminescence measurements, thereby enabling advanced crystal evaluation.

[0007] This disclosure was made in consideration of the above problems, and provides an inspection device and inspection method that can observe both photoluminescence light and Raman scattering light with a simple configuration, and can improve crystal evaluation. [Means for solving the problem]

[0008] An inspection apparatus according to one aspect of this embodiment includes: a pulse light generation means that generates pulse light having a wavelength longer than the wavelength of light corresponding to the band gap of the sample, and which generates pulse light that multiphoton-excites the sample; a focusing means including an objective lens that focuses the pulse light onto the sample with the objective lens and transmits light including photoluminescence light and Raman scattered light generated from the sample by irradiation with the pulse light to the objective lens; a first detection means for detecting the photoluminescence light transmitted through the objective lens; and a second detection means for detecting the Raman scattered light transmitted through the objective lens.

[0009] In the above inspection device, before The sample may include a semiconductor wafer.

[0010] In the inspection apparatus described above, the light-gathering means further includes a half-mirror positioned between the objective lens and the second detection means in the optical path of the pulsed light, the half-mirror transmitting either the pulsed light or the Raman scattered light and reflecting the other, a first pinhole positioned between the half-mirror and the pulsed light generating means, and a second pinhole positioned between the second detection means and the half-mirror, wherein at least the second detection means may detect the Raman scattered light generated from the portion of the sample in which the pulsed light is focused.

[0011] In the inspection apparatus described above, the half-mirror may reflect the pulsed light and transmit the Raman scattered light and the photoluminescent light, or it may transmit the pulsed light and reflect the Raman scattered light and the photoluminescent light.

[0012] In the inspection apparatus described above, the light-collecting means further includes a dichroic mirror positioned between the half-mirror and the first detection means and the second detection means, wherein the dichroic mirror may transmit either the photoluminescent light or the Raman scattered light and reflect the other.

[0013] In the inspection apparatus described above, the dichroic mirror may reflect or transmit light in a wavelength range of at least ±100 nm around the central wavelength of the pulsed light, thereby guiding the wavelength range to the second detection means.

[0014] In the inspection apparatus described above, the light-collecting means further includes a first filter disposed between the dichroic mirror and the first detection means, wherein the first filter includes at least one of a short-pass filter that transmits light with a short wavelength 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 with a wavelength greater than 400 nm and less than or equal to 700 nm, and the first detection means may detect the photoluminescent light that has passed through the first filter.

[0015] In the inspection apparatus described above, the light-collecting means further includes a second filter positioned between the dichroic mirror and the second detection means, wherein the second filter includes a filter that blocks at least the central wavelength of the pulsed light, and the second detection means may detect the Raman scattered light that has passed through the second filter.

[0016] In the inspection apparatus described above, the second filter may include a filter that blocks light below the center wavelength of the pulsed light or above the center wavelength of the pulsed light.

[0017] In the inspection apparatus described above, the wavelength of the pulsed light may include wavelengths in the visible light region.

[0018] An inspection method according to one aspect of this embodiment includes: a pulse light generation step in which a pulse light generation means generates pulse light having a wavelength longer than the wavelength of light corresponding to the band gap of the sample, and which multiphoton-excites the sample; a focusing step in which the pulse light is focused on the sample with an objective lens 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 means detects the photoluminescence light transmitted through the objective lens and a second detection means detects the Raman scattered light transmitted through the objective lens. It is equipped with.

[0019] In the above inspection method, the sample may include a semiconductor wafer.

[0020] In the above inspection method, in the focusing step, a half-mirror placed between the objective lens and the second detection means in the optical path of the pulsed light transmits either the pulsed light or the Raman scattered light and reflects the other, and at least the second detection means can detect the Raman scattered light generated from the portion of the sample in which the pulsed light is focused by a first pinhole placed between the half-mirror and the pulsed light generating means, and a second pinhole placed between the second detection means and the half-mirror.

[0021] In the above inspection method, the half mirror may reflect the pulsed light and transmit the Raman scattered light and the photoluminescent light, or it may transmit the pulsed light and reflect the Raman scattered light and the photoluminescent light.

[0022] In the above inspection method, in the light focusing step, a dichroic mirror positioned between the half mirror and the first and second detection means may transmit either the photoluminescent light or the Raman scattered light, and reflect the other.

[0023] In the above inspection method, the dichroic mirror may reflect or transmit light in a wide wavelength range of at least ±100 nm around the central wavelength of the pulsed light, thereby guiding the light in that wavelength range to the second detection means.

[0024] In the above inspection method, in the light collection step, a first filter disposed between the dichroic mirror and the first detection means, the first filter including at least one of a short-pass filter that transmits light with a short wavelength 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 with a wavelength greater than 400 nm and less than or equal to 700 nm, the photoluminescence light that has passed through the first filter may be detected by the first detection means.

[0025] In the above inspection method, in the light collection step, a second filter disposed between the dichroic mirror and the second detection means, the second filter including a filter that blocks at least the light having the central wavelength of the pulsed light, the Raman scattered light that has passed through the second filter may be detected by the second detection means.

[0026] In the above inspection method, the second filter may further include a filter that blocks light having a wavelength equal to or less than the central wavelength of the pulsed light or light having a wavelength equal to or greater than the central wavelength of the pulsed light.

[0027] In the above inspection method, the wavelength of the pulsed light may include wavelengths in the visible light region.

Advantages of the Invention

[0028] According to the present disclosure, it is possible to provide an inspection apparatus and an inspection method that can detect both photoluminescence light and Raman scattered light with a simple configuration and can enhance crystal evaluation.

Brief Description of the Drawings

[0029] [Figure 1] It is a configuration diagram illustrating an inspection apparatus according to Embodiment 1. [Figure 2] It is a flowchart diagram illustrating an inspection method according to Embodiment 1. [Figure 3] It is a configuration diagram illustrating an inspection apparatus according to Embodiment 2. [Figure 4]This is a diagram illustrating an inspection device according to Embodiment 3. [Figure 5] This graph illustrates the transmission characteristics of a dichroic mirror in the inspection apparatus according to Embodiment 3, with the horizontal axis representing wavelength and the vertical axis representing transmittance. [Figure 6] This graph illustrates the characteristics of the filter in the inspection apparatus according to Embodiment 3, with the horizontal axis representing wavelength and the vertical axis representing transmittance. [Figure 7] This graph illustrates the light detected by the first detection means and the second detection means in the inspection apparatus according to Embodiment 3, with the horizontal axis representing wavelength and the vertical axis representing transmittance. [Figure 8] This graph illustrates the light detected by the first detection means and the second detection means in the inspection apparatus according to Embodiment 3, with the horizontal axis representing wavelength and the vertical axis representing transmittance. [Figure 9] This graph illustrates the light detected by the first detection means and the second detection means in the inspection apparatus according to Embodiment 3, with the horizontal axis representing wavelength and the vertical axis representing transmittance. [Modes for carrying out the invention]

[0030] Embodiments of the present disclosure will be described below with reference to the drawings. The following description illustrates preferred embodiments of the present disclosure and does not limit the scope of the present disclosure to the following embodiments. In the following description, the same reference numerals indicate substantially the same thing.

[0031] (Embodiment 1) The inspection apparatus and inspection method according to Embodiment 1 will now be described. Figure 1 is a configuration diagram illustrating the inspection apparatus 1 according to Embodiment 1. As shown in Figure 1, the inspection apparatus 1 according to this embodiment includes a pulse light generation means 10, a light focusing means 20, and a detection means 30. The inspection apparatus 1 irradiates the sample 40, such as a semiconductor wafer, with pulse light 11 having a wavelength longer than the wavelength of light corresponding to the band gap of the sample 40. As a result, the inspection apparatus 1 observes photoluminescence light PL and Raman scattered light RS caused by multiphoton excitation resulting from the pulse light 11. In the figure, only the optical axes of the pulse light 11, photoluminescence light PL, and Raman scattered light RS are schematically shown. The sample 40 includes, for example, a semiconductor wafer made of a semiconductor material. Specifically, the semiconductor material may include wide-bandgap compound semiconductors such as silicon carbide (SiC) and GaN. However, the sample 40 is not limited to a semiconductor wafer as long as it contains a crystal having a bandgap.

[0032] The pulsed light generation means 10 generates pulsed light 11 with a wavelength longer than the wavelength of light corresponding to the band gap of the sample 40. The pulsed light generation means 10 generates pulsed light 11 that multiphoton-excites the sample 40.

[0033] In typical photoluminescence measurements, light with an energy greater than the band gap energy of the sample 40 is irradiated onto the sample 40. This allows for the measurement of photoluminescence light PL emitted when the sample 40 transitions from an excited state to a ground state.

[0034] On the other hand, in the case of photoluminescence measurement by multiphoton excitation, the sample 40 is irradiated with light that has an energy of about 1 / 2 or 1 / 3 of the energy of the sample 40's band gap. Then, the photoluminescence light PL emitted when the sample 40 transitions from the excited state to the ground state by multiphotons such as 2-photons or 3-photons is measured. Thus, in the case of photoluminescence measurement by multiphoton excitation, pulsed light 11 with a wavelength longer than the wavelength of light corresponding to the band gap of the sample 40 is used. The pulsed light generation means 10 is preferably a femtosecond laser or the like that can generate pulsed light 11 with high power. However, the pulsed light generation means 10 is not limited to a femtosecond laser.

[0035] The specifications of the pulsed light 11 may include, for example, infrared light with a central wavelength of 1040 nm and an output of 3 W. In this case, photoluminescence light PL can be generated on a sample 40 such as SiC and GaN by 3-photon excitation. Alternatively, the specifications of the pulsed light 11 may include, for example, visible light with a central wavelength of 520 nm and an output of 1 W. In this case, photoluminescence light PL can be generated on a sample 40 such as SiC and GaN by 2-photon excitation. Thus, the wavelength of the pulsed light 11 may include, for example, wavelengths in the infrared light region or wavelengths in the visible light region.

[0036] The focusing means 20 includes an objective lens 21. The focusing means 20 may also include other optical components such as a half-mirror 22 in addition to the objective lens 21. The focusing means 20 focuses the pulsed light 11 onto the sample 40 using the objective lens 21. The focusing means 20 also transmits the light 41 generated from the sample 40 by the pulsed light 11 through the objective lens 21. This allows the focusing means 20 to guide the light 41 generated from the sample 40 to the detection means 30. The light 41 generated from the sample 40 includes photoluminescent light PL and Raman scattered light RS. In the figure, the light 41 including photoluminescent light PL and Raman scattered light RS is indicated as 41(PL,RS).

[0037] The detection means 30 includes a first detection means 31 and a second detection means 32. The first detection means 31 detects photoluminescent light PL transmitted through the objective lens 21. The first detection means 31 includes a detector capable of detecting photoluminescent light PL, such as a CCD (Charge Coupled Device) sensor, a TDI (Time Delay Integration) camera, or a PMT (Photomultiplier Tube). The second detection means 32 detects Raman scattered light RS transmitted through the objective lens 21. The second detection means 32 includes a detector capable of detecting Raman scattered light RS, such as a CCD or PMT. The second detection means 32 may further include a spectrometer.

[0038] The first detection means 31 and the second detection means 32 in the detection means 30 may be configured as an integrated unit. For example, the detection means 30 may have the functions of both the first detection means 31 and the second detection means 32 and detect both photoluminescent light PL and Raman scattered light RS. Alternatively, the detection means 30 may detect both photoluminescent light PL and Raman scattered light RS by switching between the first detection means 31 and the second detection means 32 using a switching means.

[0039] Figure 2 is a flowchart illustrating an inspection method according to Embodiment 1. As shown in Figure 2, the inspection method of this embodiment comprises a pulse light generation step S11, a focusing step S12, and a detection step S13.

[0040] In the pulsed light generation step S11, first, pulsed light 11 is generated to excite the sample 40 with multiple photons. For example, the pulsed light generation means 10 is made to generate pulsed light 11 with a wavelength longer than the wavelength of light corresponding to the band gap of the sample 40.

[0041] Next, in the focusing step S12, the pulsed light 11 is focused onto the sample 40 using the objective lens 21. At the same time, the light 41 generated from the sample 40 by the irradiation of the pulsed light 11 is transmitted through the objective lens 21. The light 41 includes photoluminescent light PL and Raman scattered light RS.

[0042] Next, in detection step S13, the first detection means 31 detects the photoluminescent light PL that has passed through the objective lens 21. In addition, the second detection means 32 detects the Raman scattered light RS that has passed through the objective lens 21.

[0043] Next, the effects of this embodiment will be explained. In this embodiment, multiphoton excitation of sample 40 is performed by irradiating sample 40 with pulsed light 11 having a wavelength longer than the wavelength of light corresponding to the band gap of sample 40. This allows detection of both photoluminescence light PL and Raman scattering light RS. Crystal defects in sample 40 can be detected by photoluminescence measurement. Strain and stress inside sample 40 can be detected by Raman spectroscopy measurement. Therefore, this embodiment can detect not only crystal defects in sample 40, but also multiple types of internal anomalies, including strain and stress.

[0044] Furthermore, this embodiment observes photoluminescence light PL by multiphoton excitation with long-wavelength light, enabling simultaneous measurement of Raman scattered light RS, which is difficult with conventional photoluminescence measurements using short-wavelength light. This allows for the correspondence between the Raman scattered light RS generated at the location where the photoluminescence light PL is generated. Therefore, both photoluminescence light PL and Raman scattered light RS can be detected with a simple configuration, thereby improving crystal evaluation.

[0045] Even when attempting to detect Raman scattered light RS simultaneously with photoluminescence light PL by combining it with Raman spectroscopy based on general photoluminescence measurements, the wavelength bands of photoluminescence light PL and Raman scattered light RS are almost the same, making it difficult to detect Raman scattered light RS with effective resolution because the weaker Raman scattered light RS is masked. Furthermore, in compound semiconductors such as SiC, ultraviolet light is used as the excitation light for general photoluminescence measurements, resulting in a very narrow detection range for detectors that can detect Raman scattered light RS in response to ultraviolet light, making them extremely difficult to handle.

[0046] In contrast, this embodiment combines Raman spectral measurement with photoluminescence measurement using multiphoton excitation. Furthermore, for photoluminescence measurement using multiphoton excitation, light with wavelengths ranging from the visible light region to the infrared light region is used as the excitation light. This resolves the aforementioned problem.

[0047] Furthermore, since the pulsed light generation means 10 uses a laser light source with high output necessary for multiphoton excitation, weak Raman scattered light RS can be detected with sufficient intensity and a good signal-to-noise ratio. This makes it possible to observe Raman scattered light RS that can be used to evaluate the stress inside the crystal. For example, the amount of Stokes shift in the Raman spectrum measurement may be represented by intensity, or a reference Stokes wavenumber may be determined and the intensity ratio at that wavenumber may be displayed. The stress inside the sample 40 can be detected by the intensity of the Stokes shift.

[0048] (Embodiment 2) Next, an inspection apparatus according to Embodiment 2 will be described. In the inspection apparatus of this embodiment, the light-gathering means 20 includes a confocal optical system. Figure 3 is a configuration diagram illustrating the inspection apparatus according to Embodiment 2. As shown in Figure 3, in the inspection apparatus 2 of this embodiment, the light-gathering means 20 further includes a half mirror 22, a first pinhole 23, and a second pinhole 24 in addition to the objective lens 21. Note that the light-gathering means 20 may further include other optical members in addition to the above members.

[0049] The half mirror 22 is positioned between the objective lens 21 and the second detection means 32 in the optical path of the pulsed light 11. The half mirror 22 transmits either the pulsed light 11 or the Raman scattered light RS and reflects the other. For example, in the inspection apparatus 2 shown in Figure 3, the half mirror 22 reflects the pulsed light 11 and transmits light 41 including Raman scattered light RS. In this case, the half mirror 22 also transmits light 41 including photoluminescent light PL. Alternatively, the positions of the pulsed light generation means 10 and the detection means 30 relative to the objective lens 21 may be swapped so that the half mirror 22 transmits the pulsed light 11 and reflects light 41 including Raman scattered light RS. In this case, the half mirror 22 also reflects light 41 including photoluminescent light PL.

[0050] The first pinhole 23 is positioned between the half-mirror 22 and the pulsed light generation means 10. The second pinhole 24 is positioned between the second detection means 32 and the half-mirror 22. The first pinhole 23 and the second pinhole 24 are positioned to form a confocal optical system. In other words, at least the second detection means 32 detects the Raman scattered light RS generated from the portion of the sample 40 where the pulsed light 11 is in focus.

[0051] In the inspection method of this embodiment, in the focusing step S12, a half mirror 22 is placed between the objective lens 21 and the second detection means 32 in the optical path of the pulsed light 11, allowing either the pulsed light 11 or the Raman scattered light RS to pass through and the other to reflect it. A first pinhole 23 is placed between the half mirror 22 and the pulsed light generating means 10, and a second pinhole 24 is placed between the second detection means 32 and the half mirror 22, causing at least the second detection means 32 to detect the Raman scattered light RS generated from the portion of the sample 40 in which the pulsed light 11 is in focus.

[0052] In this embodiment, the light-gathering means 20 forms a confocal optical system. Therefore, the second detection means 32 detects the Raman scattered light RS generated from the portion of the sample 40 where the pulsed light 11 is in focus, thereby increasing the intensity of the Raman scattered light RS. In addition, the first detection means 31 detects the photoluminescence light PL generated from the portion of the sample 40 where the pulsed light 11 is in focus. This allows for photoluminescence light This allows for more precise correspondence between PL and Raman scattered light RS, thereby improving the crystal evaluation of sample 40.

[0053] (Embodiment 3) Next, an inspection apparatus and inspection method according to Embodiment 3 will be described. In this embodiment, the inspection apparatus separates photoluminescent light PL and Raman scattered light RS using a dichroic mirror. Figure 4 is a configuration diagram illustrating the inspection apparatus according to Embodiment 3. As shown in Figure 4, the light-gathering means 20 in the inspection apparatus 3 of this embodiment further includes a dichroic mirror 25. The light-gathering means 20 may further include filters 27 and 28. In addition to the optical members described above, the light-gathering means 20 may further include other optical members such as a mirror 26.

[0054] The dichroic mirror 25 is positioned between the half-mirror 22 and the first detection means 31 and the second detection means 32. The dichroic mirror 25 transmits either photoluminescent light PL or Raman scattered light RS, and reflects the other.

[0055] Figure 5 is a graph illustrating the transmission characteristics of the dichroic mirror 25 in the inspection apparatus 3 according to Embodiment 3, where the horizontal axis represents wavelength and the vertical axis represents transmittance. As shown in Figure 5, the dichroic mirror 25 reflects or transmits a wavelength range near the center wavelength of the pulsed light 11, guiding the light 41 in that wavelength range to the second detection means 32. The light 41 in that wavelength range includes not only the pulsed light 11 but also Raman scattered light RS. This wavelength range is, for example, ±100 nm of the center wavelength of the pulsed light 11. Alternatively, this wavelength range may be, for example, ±50 nm of the center wavelength of the pulsed light 11.

[0056] As an example, as shown in Figure 4, the dichroic mirror 25 reflects light 41 in the wavelength range including Raman scattered light RS, and transmits light 41 including other photoluminescent light PL. The light 41 in the wavelength range including Raman scattered light RS reflected by the dichroic mirror 25 is transmitted through the second pinhole 24. The second pinhole 24 is located between the dichroic mirror 25 and the second detection means 32. The light 41 transmitted through the second pinhole 24 is reflected by the mirror 26 and incident on the filter 28. The filter 28 is located between the dichroic mirror 25 and the second detection means 32.

[0057] Figure 6 is a graph illustrating the characteristics of the filter 28 in the inspection apparatus 3 according to Embodiment 3, where the horizontal axis represents wavelength and the vertical axis represents transmittance. As shown in Figure 6, the filter 28 includes a filter that blocks at least the light at the center wavelength of the pulsed light 11 for extracting the Raman shift. The filter 28 may include, for example, an edge filter. Specifically, the filter 28 includes a filter that blocks light at or below the center wavelength of the pulsed light 11 or at or above the center wavelength of the pulsed light 11. It is desirable for the second detection means 32 to detect Stokes scattering, which has a high intensity among the Raman scattered light RS. For this reason, the filter 28 is preferably a filter with long-pass characteristics that blocks light at or below the center wavelength of the pulsed light 11 and transmits light 41 on the longer wavelength side of the center wavelength. In this way, the second detection means 32 detects the Raman scattered light RS that has passed through the filter 28. The filter 28 may have a switching means for switching between multiple filters. The switching means switches the filter according to the wavelength of the observed Raman scattered light RS.

[0058] As shown in Figure 4, light 41, including photoluminescent light PL that has passed through the dichroic mirror 25, is incident on the filter 27. The filter 27 is positioned between the dichroic mirror 25 and the first detection means 31. The filter 27 includes at least one of the following filters: a short-pass filter that transmits light with a short wavelength 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 with a wavelength greater than 400 nm and less than or equal to 700 nm. The filter 27 may also have a switching means for switching between multiple filters. The switching means switches the filter according to the wavelength of the observed photoluminescent light PL.

[0059] Figures 7 to 9 are graphs illustrating the wavelength bands of light 41 detected by the first detection means 31 and the second detection means 32 in the inspection apparatus 3 according to Embodiment 3. The horizontal axis represents wavelength, and the vertical axis represents transmittance, indicating the intensity of light 41 detected by the first detection means 31 and the second detection means 32. As shown in Figure 7, the first detection means 31 may detect light 41 that has passed through a short-pass filter that transmits light with a short wavelength of 400 nm or less. In this case, band-edge emission of SiC and the like can be observed.

[0060] Furthermore, as shown in Figure 8, the first detection means 31 may detect light 41 that has passed through a long-pass filter that transmits light with wavelengths longer than 700 nm. In this case, S i Photoluminescence (PL) from basal plane dislocations (BPDs), also known as killer defects, present in semiconductor materials such as carbon can be observed.

[0061] Furthermore, as shown in Figure 9, the first detection means 31 may also detect light 41 that has passed through a bandpass filter that transmits light greater than 400 nm and less than or equal to 700 nm. In this case, photoluminescent light PL such as impurity emission, defect level emission, and stacking fault emission of a wide bandgap semiconductor such as SiC can be observed. In this way, the first detection means 31 detects the photoluminescent light PL that has passed through the filter 27.

[0062] The inspection method of this embodiment is a focusing step S12 In this configuration, the dichroic mirror 25 transmits either the photoluminescent light PL or the Raman scattered light RS, and reflects the other. The photoluminescent light PL that has passed through the filter 27 is detected by the first detection means 31. The Raman scattered light RS that has passed through the filter 28 is detected by the second detection means 32.

[0063] According to this embodiment, the optical path of the photoluminescent light PL detected by the first detection means 31 and the optical path of the Raman scattered light RS detected by the second detection means 32 can be separated by the dichroic mirror 25. Therefore, it is not necessary to configure the optical path of the Raman scattered light RS with a confocal optical system, nor is it necessary to configure the optical path of the photoluminescent light PL with a confocal optical system.

[0064] In multiphoton-excited photoluminescence measurements, photoluminescent light PL is highly likely to originate from the region where the pulsed light is in focus, i.e., from the region with a high photon density. Therefore, the first detection means 31 detects photoluminescence generated from such a region where the pulsed light 11 is in focus. light PL is detected. Therefore, even without a confocal optical system such as a second pinhole 24, the first detection means 31 can substantially detect photoluminescent light PL generated from the portion where the pulsed light 11 is in focus.

[0065] On the other hand, in this embodiment, the second detection means 32 detects Raman scattered light RS generated from the portion where the pulsed light 11 is in focus using a confocal optical system. This enables photoluminescence. light This allows for highly accurate correspondence between PL (Plant-Low) and Raman scattering (RS) light, thereby improving the crystal evaluation of sample 40.

[0066] In this embodiment, the optical path of the photoluminescent light PL does not need to be constructed with a confocal optical system, thus reducing the number of optical components.

[0067] Since the optical paths of the photoluminescent light PL and the Raman scattered light RS can be separated, different filters 27 and 28 corresponding to the detection target can be placed on each optical path. Therefore, desired wavelength ranges can be detected for both the photoluminescent light PL and the Raman scattered light RS.

[0068] It is desirable that the sizes of the first pinhole 23 and the second pinhole 24 be variable. By changing the sizes of the first pinhole 23 and the second pinhole 24, the size of the area in the sample 40 that is in focus with the pulsed light 11 can be changed. Therefore, the size of the observation range in the sample 40 can be changed. For example, by changing the sizes of the first pinhole 23 and the second pinhole 24 to correspond to the observation range that depends on the probability of generating photoluminescence light PL due to multiphoton excitation, the size of the observation range can be changed. light This allows for even higher precision in the correspondence between PL (photoluminescence) and Raman scattered light RS (Raman scattering). Furthermore, although the explanation assumed that the optical path of the photoluminescent light PL was not constructed using a confocal optical system, the optical path of the photoluminescent light PL may also be constructed using a confocal optical system, similar to the optical path of the Raman scattered light RS.

[0069] While embodiments of this disclosure have been described above, this disclosure includes appropriate modifications that do not impair its purpose and advantages, and is not limited by the embodiments described above. Furthermore, combinations of the configurations of Embodiments 1 to 3 also fall within the scope of the technical concept of this disclosure. [Explanation of Symbols]

[0070] 1, 2, 3 Inspection equipment 10. Pulse light generation means 11 pulsed light 20 Light-gathering means 21 Objective lens 22 Half Mirror 23. First pinhole 24. Second pinhole 25 Dichroic Mirror 26 Miller 27 filters 28 filters 30 Detection means 31 First detection means 32 Second detection means 40 samples 41 light PL photoluminescence light RS Raman scattering light

Claims

1. A pulse light generation means for generating pulse light having a wavelength longer than the wavelength of light corresponding to the band gap of a sample which is a semiconductor wafer, and which generates pulse light that causes multiphoton excitation of the sample, A focusing means including an objective lens, which focuses the pulsed light onto the sample with the objective lens, and transmits light including photoluminescence light generated from the sample by irradiation with the pulsed light having one central wavelength and Raman scattered light due to spontaneous Raman scattering generated in the sample by irradiation with the pulsed light having one central wavelength to the objective lens, A first detection means for detecting the photoluminescent light transmitted through the objective lens, A second detection means for detecting the Raman scattered light transmitted through the objective lens, A separation means provided between the first detection means and the second detection means and the objective lens for separating the light including the photoluminescent light and the Raman scattered light, wherein the separation means guides light within the range of the central wavelength and ±100 nm around the wavelength of the pulsed light to the second detection means side, and guides light with a wavelength shorter than the wavelength of the pulsed light to the first detection means side. Equipped with, Based on the detection result of the second detection means, a Raman spectrum is obtained that includes peaks of Raman scattered light at multiple wavelengths generated by spontaneous Raman scattering based on the pulsed light. Inspection device.

2. Based on the Raman spectrum, the stress inside the crystal of the semiconductor wafer is detected. The inspection apparatus according to claim 1.

3. The second detection means detects Raman scattered light on the wavelength side longer than the wavelength of the pulsed light, Based on the detection result of the second detection means, a Raman shift on the wavelength side longer than the wavelength of the pulsed light is obtained. The inspection apparatus according to claim 1.

4. The second detection means detects the Raman scattered light generated from the sample using a confocal optical system. The first detection means detects the photoluminescence light generated from the sample using a non-confocal optical system. The inspection apparatus according to claim 1.

5. The light-gathering means is A half-mirror positioned between the objective lens and the second detection means in the optical path of the pulsed light, the half-mirror transmitting either the pulsed light or the Raman scattered light and reflecting the other, A first pinhole is positioned between the half mirror and the pulse light generating means, A second pinhole is positioned between the second detection means and the half mirror, It further includes, At least the second detection means detects the Raman scattered light generated from the portion of the sample where the pulsed light is in focus, The half-mirror reflects the pulsed light and transmits the Raman scattered light and the photoluminescent light, or transmits the pulsed light and reflects the Raman scattered light and the photoluminescent light. The light-gathering means further includes a dichroic mirror positioned between the half-mirror, the first detection means, and the second detection means. The dichroic mirror transmits either the photoluminescent light or the Raman scattered light, and reflects the other. The second pinhole is positioned in the optical path of the Raman scattered light between the second detection means and the dichroic mirror. The optical path of the photoluminescent light between the first detection means and the dichroic mirror does not have a pin pole. The inspection apparatus according to claim 1.

6. The aforementioned light-gathering means is A half-mirror positioned between the objective lens and the second detection means in the optical path of the pulsed light, the half-mirror transmitting either the pulsed light or the Raman scattered light and reflecting the other, A first pinhole is positioned between the half mirror and the pulse light generating means, A second pinhole is positioned between the second detection means and the half mirror, It further includes, At least the second detection means detects the Raman scattered light generated from the portion of the sample where the pulsed light is in focus. The inspection apparatus according to any one of claims 1 to 4.

7. The half-mirror reflects the pulsed light and transmits the Raman scattered light and the photoluminescent light, or transmits the pulsed light and reflects the Raman scattered light and the photoluminescent light. The inspection apparatus according to claim 6.

8. The separation means includes a dichroic mirror positioned between the half mirror, the first detection means and the second detection means, The dichroic mirror transmits either the photoluminescent light or the Raman scattered light and reflects the other, thereby guiding light within the range of the center wavelength and ±100 nm around it of the pulsed light to the second detection means, and guiding light with a wavelength shorter than the pulsed light to the first detection means. The inspection apparatus according to claim 7.

9. The light-gathering means further includes a first filter positioned between the dichroic mirror and the first detection means, The first filter includes at least one of the following filters: a short-pass filter that transmits light with a short wavelength 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 with a wavelength greater than 400 nm and less than or equal to 700 nm. The first detection means detects the photoluminescent light that has passed through the first filter. The inspection apparatus according to claim 8.

10. The light-gathering means further includes a second filter positioned between the dichroic mirror and the second detection means, The second filter includes a filter that blocks at least the light of the central wavelength of the pulsed light, The second detection means detects the Raman scattered light that has passed through the second filter. The inspection apparatus according to claim 8.

11. The second filter includes a filter that blocks light below the center wavelength of the pulsed light or above the center wavelength of the pulsed light. The inspection apparatus according to claim 10.

12. The wavelength of the pulsed light includes wavelengths in the visible light region. The inspection apparatus according to any one of claims 1 to 5.

13. A pulsed light generation step in which a pulsed light generation means generates pulsed light having a wavelength longer than the wavelength of light corresponding to the band gap of a sample which is a semiconductor wafer, and the pulsed light is used to multiphoton-excite the sample, A focusing step in which the pulsed light is focused onto the sample with an objective lens, and the photoluminescence light generated from the sample by irradiation with the pulsed light having one central wavelength and the Raman scattered light generated by spontaneous Raman scattering in the sample by irradiation with the pulsed light having one central wavelength are transmitted to the objective lens, A detection step in which the first detection means detects the photoluminescence light transmitted through the objective lens, and the second detection means detects the Raman scattered light transmitted through the objective lens, Equipped with, In the aforementioned light-gathering step, A separation means provided between the first detection means and the second detection means and the objective lens for separating the light including the photoluminescent light and the Raman scattered light, which guides the light within the range of the central wavelength and ±100 nm around the wavelength of the pulsed light to the second detection means and guides the light with a wavelength shorter than the wavelength of the pulsed light to the first detection means. In the detection step, Based on the detection result of the second detection means, a Raman spectrum is obtained that includes peaks of Raman scattered light at multiple wavelengths generated by spontaneous Raman scattering based on the pulsed light. Testing method.

14. A method for detecting stress inside the crystal of the semiconductor wafer based on the Raman spectrum. The inspection method according to claim 13.

15. The second detection means detects Raman scattered light on the wavelength side longer than the wavelength of the pulsed light, Based on the detection result of the second detection means, a Raman shift on the wavelength side longer than the wavelength of the pulsed light is obtained. The inspection method according to claim 13.

16. The second detection means detects the Raman scattered light generated from the sample using a confocal optical system. The first detection means detects the photoluminescence light generated from the sample using a non-confocal optical system. The inspection method according to claim 13.

17. In the light-gathering step, A half-mirror positioned between the objective lens and the second detection means in the optical path of the pulsed light transmits either the pulsed light or the Raman scattered light, and reflects the other. A first pinhole is positioned between the half-mirror and the pulsed light generating means, and a second pinhole is positioned between the second detection means and the half-mirror, thereby causing at least the second detection means to detect the Raman scattered light generated from the portion of the sample in which the pulsed light is focused. The half-mirror reflects the pulsed light and transmits the Raman scattered light and the photoluminescent light, or transmits the pulsed light and reflects the Raman scattered light and the photoluminescent light. A dichroic mirror positioned between the half-mirror, the first detection means, and the second detection means transmits either the photoluminescent light or the Raman scattered light, and reflects the other. The second pinhole is positioned in the optical path of the Raman scattered light between the second detection means and the dichroic mirror. The optical path of the photoluminescent light between the first detection means and the dichroic mirror does not have a pin pole. The inspection method according to claim 13.

18. In the aforementioned light-gathering step, A half-mirror positioned between the objective lens and the second detection means in the optical path of the pulsed light transmits either the pulsed light or the Raman scattered light, and reflects the other. A first pinhole is positioned between the half-mirror and the pulsed light generating means, and a second pinhole is positioned between the second detection means and the half-mirror, thereby causing at least the second detection means to detect the Raman scattered light generated from the portion of the sample in which the pulsed light is focused. The inspection method according to any one of claims 13 to 16.

19. The half-mirror reflects the pulsed light and transmits the Raman scattered light and the photoluminescent light, or transmits the pulsed light and reflects the Raman scattered light and the photoluminescent light. The inspection method according to claim 18.

20. In the aforementioned light-gathering step, The separation means includes a dichroic mirror positioned between the half mirror, the first detection means, and the second detection means, wherein the dichroic mirror transmits either the photoluminescent light or the Raman scattered light and reflects the other, thereby guiding light within a range of ±100 nm around the center wavelength of the pulsed light to the second detection means and guiding light with a wavelength shorter than the pulsed light to the first detection means. The inspection method according to claim 19.

21. In the aforementioned light-gathering step, A first filter is positioned between the dichroic mirror and the first detection means, and the first filter includes at least one of the following filters: a short-pass filter that transmits light with a short wavelength 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 with a wavelength greater than 400 nm and less than or equal to 700 nm. The first detection means detects the photoluminescent light that has passed through the first filter. The inspection method according to claim 20.

22. In the aforementioned light-gathering step, A second filter is disposed between the dichroic mirror and the second detection means, and the second filter includes a filter that blocks at least the light of the central wavelength of the pulsed light, thereby causing the second detection means to detect the Raman scattered light that has passed through the second filter. The inspection method according to claim 20.

23. The second filter further includes a filter that blocks light below the center wavelength of the pulsed light or above the center wavelength of the pulsed light. The inspection method according to claim 22.

24. The wavelength of the pulsed light includes wavelengths in the visible light region. The inspection method according to any one of claims 13 to 17.

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