Inspection device and inspection method

Abstract

To provide an inspection device and an inspection method with which, while reducing damage to a sample, it is possible to inspect a sample with high throughput.SOLUTION: An inspection device 1 according to the present embodiment comprises: a separation unit 111 for separating illumination light L10 into a plurality of N beams of light; a condensing lens 119 for condensing the illumination light L10 including the N beams of light on a sample 500 and thereby forms N spot regions SA on the sample 500; a detection unit 220 provided at a position conjugate with the pupil of the condensing lens 119, for detecting a secondary beam of light from the N spot regions SA of the sample 500; a scan unit 120 for controlling a drive unit KD that moves the spot regions SA on the sample 500 and thereby scanning the spot regions SA on the sample 500; and a control unit 300 for controlling the separation unit 111 so as to switch the number of beams of light from N to M (=1 or greater to less than N).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an inspection device and an inspection method. [Background technology]

[0002] Patent Document 1 describes an apparatus for irradiating a sample with excitation light and observing photoluminescence light (hereinafter referred to as PL light). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-194718 Summary of the Invention [Problem to be solved by the invention]

[0004] When observing PL light by scanning a wide area of ​​a sample, it is necessary to observe with high throughput and with reduced damage to the sample.

[0005] The present disclosure has been made in consideration of such problems, and provides an inspection apparatus and an inspection method that can inspect a sample with high throughput while reducing damage to the sample. [Means for solving the problem]

[0006] An inspection device according to one aspect of this embodiment includes a separation unit that separates illumination light into a plurality of N light beams, a condenser lens that forms the N spot areas on a sample by focusing the illumination light including the N light beams on the sample, a detection unit that is provided at a position conjugate with a pupil of the condenser lens and detects secondary light rays from the N spot areas on the sample, a scanning unit that scans the spot areas over the sample by controlling a driving unit that moves the spot areas over the sample, and a control unit that controls the separation unit to switch the N light beams to M, which is 1 or more and less than N. and a control unit which executes a first observation mode to acquire a signal output by the detection unit when the N spot areas are scanned on the sample, and determines whether a predetermined observation target has been detected on the sample based on the signal output in the first observation mode, and if the predetermined observation target has been detected on the sample, executes a second observation mode to illuminate a position where the predetermined observation target has been observed with the M light beams and acquires the signal output by the detection unit, and determines the observation target based on the signal output in the second observation mode.

[0007] In the above-mentioned inspection device, the control unit may determine the content of the observation object by integrating the signal output of the detection unit when illuminating a position where the specified observation object is observed at multiple sampling times in the second observation mode.

[0008] In the above-mentioned inspection device, in the first observation mode, the control unit may acquire an illumination position, which is the position of the illumination light including the N spot areas, in association with the signal output of the detection unit at the illumination position, and may accumulate the signal outputs for a specific position at multiple sampling times to determine whether a specified observation target has been observed at the specific position on the sample.

[0009] In the above inspection apparatus, the specific position may include a position at which a predetermined defect candidate image is detected on the sample.

[0010] In the above-described inspection apparatus, the control unit may integrate the output signal of the detection unit at the specific position in the second observation mode.

[0011] In the above inspection apparatus, the illumination light may include excitation light that excites the sample, and the secondary light may include photoluminescence light from the sample.

[0012] In the above inspection apparatus, the illumination light may include multi-photon excitation light that excites the sample with a plurality of photons.

[0013] In the above inspection apparatus, the interval between adjacent spot areas may be set based on the thermal conductivity of the sample.

[0014] An inspection method according to one aspect of the present embodiment includes the steps of: separating illumination light into a plurality of N light beams using a separation unit; forming the N spot areas on a sample by focusing the illumination light including the N light beams on the sample using a condenser lens; detecting secondary light rays from the N spot areas on the sample using a detection unit provided at a position conjugate with a pupil of the condenser lens; scanning the spot areas on the sample with a scanning unit by controlling a drive unit that moves the spot areas on the sample; and detecting the secondary light rays from the detection unit when the N spot areas have been scanned on the sample. the step of executing a first observation mode to acquire a signal output by the detection unit; the step of determining whether a predetermined observation target has been detected in the sample based on the signal output in the first observation mode; the step of switching the N light beams to M light beams, which is at least 1 but less than N, by the separation unit when the predetermined observation target has been detected in the sample; the step of executing a second observation mode to illuminate a position where the predetermined observation target has been observed with the M light beams and acquire the signal output by the detection unit; and the step of determining the observation target based on the signal output in the second observation mode.

[0015] In the above inspection method, in the step of executing the second observation mode, signal outputs of the detection unit when a position where the specified observation object is observed is illuminated at a plurality of sampling times may be integrated, and in the step of determining the observation object, the content of the observation object may be determined.

[0016] In the above inspection method, in the step of executing the first observation mode, an illumination position, which is the position of the illumination light including the N spot areas, and the signal output of the detection unit at the illumination position may be associated and acquired, and the signal output for a specific position at multiple sampling times may be accumulated to determine whether a specified observation target has been observed at the specific position on the sample.

[0017] In the above inspection method, the specific position may include a position at which a predetermined defect candidate image is detected on the sample.

[0018] In the above inspection method, in the step of executing the second observation mode, the output signal of the detection unit at the specific position may be integrated.

[0019] In the above inspection method, the illumination light may include excitation light that excites the sample, and the secondary light may include photoluminescence light from the sample.

[0020] In the above inspection method, the illumination light may include multi-photon excitation light that excites the sample with a plurality of photons.

[0021] In the above inspection method, the interval between the adjacent spot areas may be set based on the thermal conductivity of the sample. [Effects of the Invention]

[0022] According to the present disclosure, it is possible to provide an inspection apparatus and an inspection method that can inspect a sample with high throughput while reducing damage to the sample. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a configuration diagram illustrating an inspection device according to a first embodiment. [Figure 2] 3 is a plan view illustrating spot areas formed by illuminating a sample surface with a plurality of light beams in illumination light in the inspection device according to the first embodiment. FIG. [Figure 3] 3 is a diagram illustrating an example of illumination light including a spot area that moves on a sample surface in the inspection device according to the first embodiment. FIG. [Figure 4] 3 is a diagram illustrating an example of illumination light including a spot region that moves in an orthogonal plane in the inspection device according to the first embodiment. FIG. [Figure 5] 10 is an image illustrating a signal output acquired in a first observation mode in the inspection device according to the first embodiment, showing an image at an illumination position. [Figure 6] 10 is an image illustrating a signal output acquired in a first observation mode in the inspection device according to the first embodiment, and shows an image accumulated at a sampling time t1 at an illumination position. [Figure 7] 10 is an image illustrating a signal output acquired in a first observation mode in the inspection device according to the first embodiment, and shows an image accumulated at a sampling time t2 at an illumination position. [Figure 8] 10 is an image illustrating a signal output acquired in a first observation mode in the inspection device according to the first embodiment, and shows an image accumulated at a sampling time t1 at an illumination position. [Figure 9] 10 is an image illustrating a signal output acquired in a first observation mode in the inspection device according to the first embodiment, and shows an image accumulated at a sampling time t2 at an illumination position. [Figure 10] 10 is an image illustrating a signal output acquired in a first observation mode in the inspection device according to the first embodiment, and shows an image accumulated at a sampling time t3 at an illumination position. [Figure 11] 10 is an image illustrating a signal output acquired in the second observation mode in the inspection device according to the first embodiment, and shows an image accumulated at sampling time t4 at the illumination position. [Figure 12] 10 is an image illustrating a signal output acquired in the second observation mode in the inspection device according to the first embodiment, and shows an image accumulated at the sampling time t5 at the illumination position P3. [Figure 13] FIG. 2 is a flowchart illustrating an inspection method using the inspection device according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The following description shows preferred embodiments of the present disclosure, and the scope of the present disclosure is not limited to the following embodiments. In the following description, components with the same reference numerals indicate substantially similar content.

[0025] (Embodiment 1) An inspection device and an inspection method according to embodiment 1 will be described. FIG. 1 is a configuration diagram illustrating an inspection device 1 according to embodiment 1. As shown in FIG. 1, the inspection device 1 includes an illumination optical system 100, a detection optical system 200, and a control unit 300. In addition to these, the inspection device 1 may further include a light source 400. Note that the inspection device 1 does not need to include the light source 400 as long as it is configured to introduce illumination light L10.

[0026] The illumination optical system 100 illuminates the sample 500 with illumination light L10. The sample 500 is placed on a stage STG. The stage STG may be an XYZ drive stage that is movable in three orthogonal axis directions. The stage STG may also have a function for rotating around three axes. The light source 400 generates illumination light L10. The illumination light L10 may include excitation light that excites the sample 500. In other words, the illumination light L10 may excite a material contained in the sample 500. Note that the illumination light L10 is not limited to light that includes excitation light, as long as it is light that illuminates the sample 500. In the following, the illumination light L10 will be described as light that includes excitation light.

[0027] The illumination light L10 may include a wavelength longer than the wavelength corresponding to the band gap of the material contained in the sample 500. Therefore, the illumination light L10 may include multi-photon excitation light that excites the sample 500 with multiple photons. Specifically, the illumination light L10 may include a wavelength corresponding to energy that causes two-photon excitation of the sample 500, or may include a wavelength corresponding to energy that causes three-photon excitation. For example, when the sample 500 includes a semiconductor or a compound semiconductor, the illumination light L10 may include a wavelength of 500 nm to 600 nm.

[0028] For example, if the sample 500 includes silicon carbide (SiC), two-photon excitation may be achieved using illumination light L10 including a wavelength of 520 nm. In this case, three-photon excitation can be achieved by using illumination light L10 including wavelengths of 800 nm and 1040 nm.

[0029] Furthermore, when the sample 500 contains gallium nitride (GaN), two-photon excitation may be performed using illumination light L10 containing a wavelength of 520 nm. In this case, three-photon excitation can be achieved by using illumination light L10 containing wavelengths of 800 nm and 1040 nm.

[0030] Furthermore, when the sample 500 contains gallium oxide (Ga2O3), two-photon excitation may be performed using illumination light L10 containing a wavelength of 520 nm. In this case, three-photon excitation can be achieved by using illumination light L10 containing a wavelength of 800 nm, and four-photon excitation can be achieved by using illumination light L10 containing a wavelength of 1040 nm.

[0031] Furthermore, when the sample 500 contains diamond, three-photon excitation may be achieved using illumination light L10 containing a wavelength of 520 nm. In this case, four-photon excitation can be achieved by using illumination light L10 containing a wavelength of 800 nm, and five-photon excitation can be achieved by using illumination light L10 containing a wavelength of 1040 nm.

[0032] The light source 400 that generates the illumination light L10 may include a pulsed laser that generates illumination light L10 having a wavelength of 500 nm to 600 nm. For example, the light source 400 may be a femtosecond laser that generates excitation light with a wavelength of 520 nm.

[0033] Patent Document 1 describes the observation of internal defects in compound semiconductors using PL light generated by multiphoton excitation using an 800 nm or 1030 nm femtosecond laser. However, indirect transition semiconductors emit weak PL light. This results in a poor signal-to-noise ratio (SN ratio) of PL light. Furthermore, the PL light of the compound semiconductor being observed has wavelengths ranging from the ultraviolet to the visible range. Therefore, a device such as that described in Patent Document 1 requires an objective lens that transmits light ranging from the PL light wavelength range to the infrared range of 800 nm or 1030 nm, which is the wavelength of the femtosecond laser. However, it is difficult to prepare an objective lens that is aberration-corrected from PL light to light in the infrared range. This also hinders the improvement of the SN ratio of PL light.

[0034] In this embodiment, for example, by using illumination light L10 having a wavelength of 500 nm to 600 nm, the aberration correction of the lens can be extended from the wavelength range of PL light to the wavelength range of 500 nm to 600 nm. This improves the signal-to-noise ratio of PL light. Note that in this embodiment, the wavelength of illumination light L10 is not limited to 500 nm to 600 nm.

[0035] Here, for convenience of explanation of the inspection apparatus 1, an XYZ Cartesian coordinate system is introduced. A plane parallel to the sample surface 510 of the sample 500 (for example, the top surface of the sample 500) is defined as the XY plane. One direction in the plane parallel to the sample surface 510 is defined as the X-axis direction, and a direction perpendicular to the X-axis direction is defined as the Y-axis direction. A direction perpendicular to the sample surface 510 is defined as the Z-axis direction. The +Z-axis direction may be referred to as the upward direction, and the -Z-axis direction may be referred to as the downward direction. Note that the terms upward and downward are used for convenience of explanation of the inspection apparatus 1, and do not indicate the directions in which the actual inspection apparatus 1 is disposed.

[0036] For ease of explanation of the direction in which illumination light L10 moves, an αβγ Cartesian coordinate system is introduced. An orthogonal plane 610 perpendicular to the optical path L11 of illumination light L10 at a conjugate position on the optical path L11 of illumination light L10 that is conjugate to sample surface 510 is defined as the αβ plane. The direction perpendicular to the αβ plane is defined as the γ-axis direction. For example, the optical axes of lenses 116a and 116b extend in the γ-axis direction.

[0037] The illumination optical system 100 includes an optical member 110, a driving unit KD, and a scanning unit 120. The optical member 110 includes, for example, a separating unit 111, a mirror 112, an optical element 113a, lenses 114a and 114b, optical elements 115a, lenses 116a and 116b, a λ / 4 plate 117, a dichroic mirror 118, and a condenser lens 119. Note that the optical member 110 may further include other optical members 110, or some of these optical members 110 may be omitted.

[0038] Illumination light L10 generated by the light source 400 is incident on the separator 111. The separator 111 separates the illumination light L10 into a plurality of N luminous fluxes. The separator 111 also separates the illumination light L10 into M luminous fluxes, which are equal to or greater than 1 but less than N. In FIG. 1, the separator 111 separates the illumination light L10 into two luminous fluxes, where N=2. Note that the separator 111 may separate the illumination light L10 into three or more luminous fluxes as long as it separates the illumination light into a plurality of N luminous fluxes. The separator 111 may include a Diffractive Optical Element (DOE), a Spatial Light Modulator (SLM), or the like. The separator 111 switches the luminous fluxes from N to M or from M to N under the control of the controller 300.

[0039] Fig. 2 is a plan view illustrating spot areas SA formed by illuminating a sample surface 510 with multiple light beams in illumination light L10 in the inspection device 1 according to embodiment 1. As shown in Fig. 2, illumination light L10 is condensed onto the sample surface 510 by a condenser lens 119, thereby forming multiple N spot areas SA on the sample surface 510. In Fig. 2, separation unit 111 splits illumination light L10 into two, so that two spot areas SA are formed on the sample surface 510.

[0040] The distance between adjacent spot areas SA is defined as length D1. If the resolution when there is one spot area SA is defined as length D2, the resolution when two spot areas SA are formed is length (D1 + D2). Therefore, the resolution when two spot areas SA are formed is lower than the resolution when there is one spot area SA. However, by forming two spot areas SA, the intensity of the PL light PL generated from the sample 500 can be doubled, and image noise can be reduced.

[0041] The distance D1 between adjacent spot areas SA may be set based on the thermal conductivity of the sample 500. For example, if the thermal conductivity of the sample 500 is high, heat is less likely to accumulate in the spot area SA, and thermal damage can be reduced. Therefore, the distance D1 may be reduced to improve the resolution.

[0042] Illumination light L10, which includes a plurality of N light beams separated by separation unit 111, is reflected by mirror 112. Mirror 112 may be a prism, a polarizing beam splitter, or the like. Illumination light L10 reflected by mirror 112 is incident on optical element 113a.

[0043] The optical element 113a includes, for example, a galvanometer mirror X113. In the following description, the optical element 113a will be described as the galvanometer mirror X113. Note that the optical element 113a is not limited to the galvanometer mirror X113 as long as it can scan the illumination light L10 in the α-axis direction. For example, the optical element 113a may be a polygon mirror or the like. When the optical element 113a includes the galvanometer mirror X113, the galvanometer mirror X113 has a driver KD.

[0044] The illumination light L10 may be incident on the galvanometer mirror X113 as parallel light. The galvanometer mirror X113 reflects the incident illumination light L10. The angle of the reflective surface of the galvanometer mirror X113 is changed by a driver KD. This causes the galvanometer mirror X113 to change the direction in which the illumination light L10 is reflected relative to the direction in which the illumination light L10 is incident.

[0045] Fig. 3 is a diagram illustrating illumination light L10 including a spot area SA that moves on a sample plane 510 in the inspection device 1 according to embodiment 1. Fig. 4 is a diagram illustrating illumination light L10 including a spot area SA that moves on an orthogonal plane 610 in the inspection device 1 according to embodiment 1. The spot area SA included in illumination light L10 is omitted in Figs. 3 and 4.

[0046] 3 and 4, for example, the galvanometer mirror X113 changes the reflecting surface so that the illumination light L10 moves in the X-axis direction within a plane parallel to the sample surface 510 of the sample 500. Corresponding to the X-axis direction along which the illumination light L10 moves on the sample surface 510, the direction along which the illumination light L10 moves on an orthogonal plane 610 perpendicular to the optical path L11 of the illumination light L10 is defined as the α-axis direction.

[0047] When illumination light L10 moves in the X-axis direction on sample surface 510, illumination light L10 moves in the α-axis direction on orthogonal plane 610. Therefore, galvanometer mirror X113 changes the reflecting surface so that illumination light L10 moves in the α-axis direction on orthogonal plane 610 perpendicular to optical path L11.

[0048] Note that the direction in which illumination light L10 moves on the orthogonal plane 610 is defined as the α-axis direction, corresponding to the X-axis direction in which illumination light L10 moves on the sample plane 510, but this is not limiting. Depending on the number and type of optical members 110 arranged on the optical path L11 of illumination light L10, the X-axis direction on the sample plane 510 may correspond to a direction other than the α-axis direction, such as the β-axis direction on the orthogonal plane 610.

[0049] The paths along which illumination light L10 moves in the X-axis direction on sample surface 510 are called movement paths 521 to 523. The galvanometer mirror X113 may change its reflecting surface so that illumination light L10 moves along multiple movement paths 521 to 523 on sample surface 510. Movement paths 521 to 523 are collectively called movement path 520.

[0050] The paths along which illumination light L10 moves in the α-axis direction on orthogonal plane 610 are called movement paths 621 to 623. The galvanometer mirror X113 may change its reflecting surface so that illumination light L10 moves along multiple movement paths 621 to 623 on orthogonal plane 610. The movement paths 621 to 623 are collectively called movement path 620.

[0051] Illumination light L10 reflected by galvanometer mirror X113 is incident on lens 114a. Lens 114a focuses the incident illumination light L10. Illumination light L10 focused by lens 114a is focused at focusing point IF1. Focusing point IF1 may be a position conjugate to sample surface 510. A position conjugate to sample surface 510 is sometimes called a conjugate position. Illumination light L10 focused at focusing point IF1 passes through focusing point IF1, then travels while expanding, and is incident on lens 114b. Lens 114b converts the incident illumination light L10 into parallel light.

[0052] The illumination light L10 converted into parallel light by the lens 114b is incident on the optical element 115a. The optical element 115a includes, for example, a galvanometer mirror Y115. In the following description, the optical element 115a will be described as the galvanometer mirror Y115. Note that the optical element 115a is not limited to the galvanometer mirror Y115 and may be a polygon mirror or the like as long as it can scan the illumination light L10 in the β-axis direction. When the optical element 115a includes the galvanometer mirror Y115, the galvanometer mirror Y115 has a driver KD. The galvanometer mirror Y115 reflects the incident illumination light L10. The driver KD changes the angle of the reflecting surface of the galvanometer mirror Y115. As a result, the galvanometer mirror Y115 changes the direction in which the illumination light L10 is reflected relative to the direction in which the illumination light L10 is incident.

[0053] 4, for example, the galvanometer mirror Y115 changes the reflecting surface so that the illumination light L10 moves in the −β-axis direction, for example, at an end in the +α-axis direction on the movement path 621. The galvanometer mirror Y115 also changes the reflecting surface so that the illumination light L10 moves in the −β-axis direction, for example, at an end in the −α-axis direction on the movement path 622. In this way, the galvanometer mirror Y115 changes the reflecting surface so that the illumination light L10 moves in the β-axis direction on the orthogonal plane 610.

[0054] The illumination light L10 reflected by the galvanometer mirror Y115 is incident on the lens 116a. The lens 116a focuses the incident illumination light L10. The illumination light L10 focused by the lens 116a is focused at a focusing point IF2. The focusing point IF2 may be a position conjugate with the sample surface 510. After passing through the focusing point IF2, the illumination light L10 travels while expanding and is incident on the lens 116b. The lens 116b converts the incident illumination light L10 into parallel light.

[0055] The illumination light L10 converted into parallel light by the lens 116b is incident on the λ / 4 plate 117. The λ / 4 plate 117 changes the polarization state of the incident illumination light L10. For example, the λ / 4 plate 117 converts incident linearly polarized light into circularly polarized light. The λ / 4 plate 117 also converts incident circularly polarized light into linearly polarized light. The illumination light L10, whose polarization state has been changed by the λ / 4 plate 117, is reflected by the dichroic mirror 118. The dichroic mirror 118 reflects light of a predetermined wavelength in the illumination light L10 and transmits light of another predetermined wavelength. The illumination light L10 reflected by the dichroic mirror 118 is incident on the condenser lens 119. The condenser lens 119 functions as an objective lens. The condenser lens 119 condenses the incident illumination light L10 onto the sample 500.

[0056] The condenser lens 119 condenses the illumination light L10 containing N light beams onto the sample 500, thereby forming N spot areas SA on the sample 500 (on the sample surface 510).

[0057] A driver KD of the galvanometer mirror X113 drives the galvanometer mirror X113 so as to move the illumination light L10 that excites the sample 500 in a first direction in a plane parallel to the sample surface 510 of the sample 500. Specifically, the driver KD drives the galvanometer mirror X113 so that the illumination light L10 has N spot regions SA with components in the X-axis direction on the sample surface 510 of the sample 500. As a result, the N spot regions SA in the illumination light L10 move in the orthogonal plane 610, for example, in the α-axis direction.

[0058] Furthermore, the driver KD of the galvanometer mirror Y115 drives the galvanometer mirror Y115 so as to move the illumination light L10 that excites the sample 500 in a second direction in a plane parallel to the sample surface 510 of the sample 500. Specifically, the driver KD drives the galvanometer mirror Y115 so that the illumination light L10 has N spot regions SA in the Y-axis direction on the sample surface 510 of the sample 500. As a result, the N spot regions SA in the illumination light L10 move in the orthogonal plane 610, for example, in the β-axis direction.

[0059] The scanning unit 120 controls the driving unit KD of the galvanometer mirror X113 and the galvanometer mirror Y115. The scanning unit 120 controls the driving unit KD, which moves the spot area SA on the sample 500 (on the sample surface 510), to scan the sample 500 with the illumination light L10 including the spot area SA. The scanning unit 120 illuminates the sample 500 with multiple spot areas SA and scans them as a single focused spot. The scanning unit 120 moves the illumination light L10 on a movement path 620 along the α-axis direction on the orthogonal surface 610. Furthermore, by controlling the driving unit KD, the scanning unit 120 moves the illumination light L10 to an end in the α-axis direction on the orthogonal surface 610, and then moves the illumination light L10 in the β-axis direction, for example.

[0060] 1, the detection optical system 200 includes an optical element 210 and a detection unit 220. The optical element 210 includes a condenser lens 119, a dichroic mirror 118, lenses 211a and 211b, and a filter 213. The condenser lens 119 and the dichroic mirror 118 are optical elements of the illumination optical system 100 and also of the detection optical system 200. Note that the optical element 210 may further include other optical elements 210, or some of these optical elements 210 may be omitted.

[0061] The condenser lens 119 focuses the illumination light L10 onto the sample 500. Secondary light rays are emitted from the sample 500 illuminated with the illumination light L10, which includes excitation light. The secondary light rays include, for example, PL light PL, as well as scattered light and reflected light L20. The PL light PL generated from the sample 500, and the scattered light and reflected light L20 resulting from scattering of the illumination light L10 by the sample 500 are incident on the condenser lens 119. The condenser lens 119 focuses the incident PL light PL, reflected light L20, etc. The PL light PL, reflected light L20, etc. focused by the condenser lens 119 are incident on the dichroic mirror 118. The dichroic mirror 118 may transmit the PL light PL and reflect the reflected light L20, etc.

[0062] The PL light PL that has passed through the dichroic mirror 118 is incident on the lens 211a. The lens 211a focuses the incident PL light PL. The PL light PL that has been focused by the lens 211a is focused at a focusing point IF3. After being focused at the focusing point IF3, the PL light PL travels while diverging and is incident on the lens 211b.

[0063] The lens 211b converts the incident PL light PL into parallel light. The parallel PL light PL that has passed through the lens 211b is incident on the filter 213. The filter 213 includes, for example, a short-pass filter. The filter 213 transmits the PL light PL. The PL light PL that has passed through the filter 213 is incident on the detection unit 220.

[0064] The detection unit 220 is provided at a position conjugate with the pupil of the condenser lens 119. The detection unit 220 detects secondary light beams from the N spot areas SA of the sample 500. The detection unit 220 detects the secondary light beams from the N spot areas SA all at once. Since the light receiving surface of the detection unit 220 is located at a position conjugate with the pupil of the condenser lens 119, the secondary light beams from the N spot areas SA can be detected all at once. For example, the detection unit 220 detects PL light PL generated from the sample 500. Therefore, the secondary light beams may include PL light PL from the sample 500.

[0065] In the large focused spot created by a low-magnification objective lens, the intensity of the excitation light per unit area is low, making multiphoton excitation unlikely. However, in the case of multiple small spot areas SA, the intensity of the excitation light per unit area in each spot area SA is high, so multiphoton excitation occurs. Since multiple spot areas SA are considered to be one large focused spot, the resolution may be lower than that of a single focused spot. However, since the intensity of the PL light PL is increased by the number of spot areas SA, images with less noise can be obtained.

[0066] The detection unit 220 may include a sensor such as a PMT (Photomultiplier Tube). Note that the detection unit 220 may include a sensor other than a PMT as long as it detects the PL light PL generated from the sample 500. The detection unit 220 detects defects and the like in the sample 500 from the PL light PL detected by the sensor.

[0067] The control unit 300 is connected to the illumination optical system 100, the detection optical system 200, the light source 400, and the stage STG in a state in which information can be transmitted via communication means such as wireless or wired. The control unit 300 may also be connected to the separation unit 111, the drive unit KD, and the scanning unit 120 in the illumination optical system 100 in a state in which information can be transmitted. The control unit 300 may also be connected to the detection unit 220 in the detection optical system 200 in a state in which information can be transmitted.

[0068] The control unit 300 adjusts the illumination light L10. For example, the control unit 300 adjusts the characteristics of the illumination light L10. The characteristics of the illumination light L10 include, for example, the intensity of the illumination light L10 and the energy of the illumination light L10. The energy of the illumination light L10 may include the magnitude of the output of the illumination light L10 output from the light source 400, or may include energy related to hc / λ derived from the wavelength λ of the illumination light L10.

[0069] The control unit 300 controls the separation unit 111. The control unit 300 controls the separation unit 111 to separate the illumination light L10 into a plurality of N light beams. The control unit 300 also controls the separation unit to switch the number of light beams from N to M, which is equal to or greater than 1 but less than N.

[0070] The control unit 300 may move the focusing position of the illumination light L10 in the thickness direction of the sample 500. For example, the control unit 300 controls the stage STG to move the focusing position of the illumination light L10 in the thickness direction of the sample 500. The control unit 300 may also control the optical member 110 to move the focusing position of the illumination light L10 in the thickness direction of the sample 500.

[0071] The illumination light L10 including excitation light may have a larger spot the deeper inside the sample 500 due to, for example, the influence of spherical aberration of the objective lens. Therefore, the efficiency of generating PL light PL by excitation light inside the sample 500 may decrease, resulting in a decrease in PL light PL from inside the sample 500. Therefore, the control unit 300 may increase the intensity of the illumination light L10 the deeper inside the sample 500 to compensate for such a decrease in the efficiency of generating PL light PL inside the sample 500.

[0072] The control unit 300 acquires from the detection unit 220 the signal output by the detection unit 220 when N spot areas SA are scanned on the sample 500. The mode in which signal outputs from the N spot areas SA are acquired in this manner is called a first observation mode. The control unit 300 executes the first observation mode. In the first observation mode, the control unit 300 acquires an illumination position, which is the position of the illumination light L10 including the N spot areas SA, and a signal output from the detection unit 220 at the illumination position, in association with each other. The illumination position, which is the position of the illumination light L10 including the N spot areas SA, may be arbitrarily determined as a position representative of the N spot areas SA. For example, the center point of any spot area SA among the N spot areas SA may be the illumination position, or the center point of the N spot areas SA may be the illumination position.

[0073] FIG. 5 is an image illustrating a signal output acquired in the first observation mode in the inspection device 1 according to the first embodiment, showing an image G11 at an illumination position P1. As shown in FIG. 5, the control unit 300 acquires an image G11 formed based on the signal output of the detection unit 220 at the illumination position P1 in association with the illumination position P1. When the control unit 300 executes the first observation mode, the control unit 300 determines whether a predetermined observation target has been detected in the sample 500 based on the signal output of the detection unit 220 in the first observation mode. For example, the control unit 300 determines that the predetermined observation target has not been detected in the image G11 associated with the illumination position P1.

[0074] 6 and 7 are images illustrating signal outputs acquired in the first observation mode by the inspection device 1 according to the first embodiment. FIG. 6 shows an image G21 acquired at a sampling time t1 at the illumination position P2, and FIG. 7 shows an image G22 obtained by integrating the image G21 with an image acquired at a sampling time t2 at the illumination position P2. As shown in FIGS. 6 and 7, the control unit 300 may acquire an image at the illumination position P2 based on a signal output obtained by integrating output signals at multiple sampling times (e.g., t1 and t2). This allows the control unit 300 to acquire an image at the illumination position P2 with reduced noise. The control unit 300 may acquire the image G22 obtained by integrating the output signals at the illumination position P2 at multiple sampling times (e.g., t1 and t2) in association with the illumination position P2. The control unit 300 may determine that the predetermined observation target is not detected in the image G22 obtained by integrating the output signals at the multiple sampling times (e.g., t1 and t2) associated with the illumination position P2.

[0075] 8 to 10 are images illustrating signal outputs acquired in the first observation mode in the inspection device 1 according to the first embodiment. Fig. 8 shows image G31 based on the output signal at illumination position P3 at sampling time t1. Fig. 9 shows image G32 based on the output signal obtained by integrating the output signal at illumination position P3 at sampling time t1 with the output signal at illumination position P3 at sampling time t2 (or may be referred to as an image obtained by integrating image G31 with an image based on the output signal at sampling time t2). Fig. 10 shows image G33 based on the output signal at illumination position P3 at sampling time t3 (or an image based on the output signal at illumination position P3 at sampling time t3). As shown in Figs. 8 to 10, the control unit 300 acquires image G32 based on the output signal at illumination position P3 at multiple sampling times (t1 and t2) and image G33 based on the output signal at illumination position P3 at multiple sampling times (t1 to t3) in association with the illumination position P3.

[0076] 8 to 10, FIG. 8 shows image G31 based on the output signal at illumination position P3 at sampling time t1, and is an example of an image for which it is determined that the predetermined observation target is not detected. FIG. 9 shows image G32 based on the integration of the output signal at illumination position P3 up to sampling time t2, and is an example of an image for which it is determined that the predetermined observation target is not detected. FIG. 10 shows image G33 based on the integration of the output signal at illumination position P3 up to sampling time t3, and is an example of an image for which it is determined that the predetermined observation target is detected. For example, the control unit 300 determines whether the predetermined observation target is detected in the image associated with illumination position P3 (G31 at t1, G32 at t2, and G33 at t3) for each sampling time. According to the examples of FIGS. 8 to 10, the control unit 300 determines that the predetermined observation target is detected at illumination position P3 at a determination timing after sampling time t3. In this way, the control unit 300 integrates signal outputs for a specific position at multiple sampling times to determine whether the predetermined observation target is observed at a specific position on the sample 500. The specific position includes a position where a predetermined defect candidate image is detected for the sample 500. For example, the specific position is illumination position P3. The predetermined defect candidate image includes an image where a predetermined observation target is detected, for example, image G33.

[0077] When a predetermined observation target is detected in the sample 500, the control unit 300 illuminates the position where the predetermined observation target is observed with M light beams and acquires a signal output by the detection unit 220. This mode of acquiring signal outputs from M spot areas SA is called a second observation mode. The control unit 300 executes the second observation mode.

[0078] 11 and 12 are images illustrating signal outputs acquired in the second observation mode in the inspection device 1 according to embodiment 1. Fig. 11 shows image G34 based on output signals at illumination position P3 at sampling time t4, and Fig. 12 shows image G35 obtained by further integrating output signals at illumination position P3 at sampling time t5. Note that image G34 may also be an image based on signals obtained by integrating output signals at illumination position P3 at sampling times prior to sampling time t4.

[0079] 11 and 12, in the second observation mode, the control unit 300 acquires the output signal of the detection unit 220 at the illumination position P3, which is a specific position observed in the first observation mode. The control unit 300 may integrate the output signal at the illumination position P3 at multiple sampling times t4 and t5. The control unit 300 then determines the observation target based on the signal output in the second observation mode. Note that in the second observation mode, the control unit 300 may integrate the signal output of the detection unit 220 when illuminating the position where the specific observation target was observed at multiple sampling times t4 and t5 to determine the content of the observation target.

[0080] <Testing method> Next, a description will be given of an inspection method using the inspection device 1. Fig. 13 is a flow chart illustrating an inspection method using the inspection device 1 according to the first embodiment.

[0081] 13, the control unit 300 separates the illumination light L10 into a plurality of N light beams by the separation unit 111. The illumination light L10 may include excitation light that excites the sample 500, or may include multi-photon excitation light that excites the sample 500 with a plurality of photons.

[0082] Next, as shown in step S12, the illumination light L10 including N light beams is focused onto the sample 500 by the focusing lens 119, thereby forming N spot areas SA on the sample 500. The interval between adjacent spot areas SA may be set based on the thermal conductivity of the sample 500.

[0083] Next, as shown in step S13, the detection unit 220, which is provided at a position conjugate with the pupil of the condenser lens 119, detects secondary light beams from the N spot areas SA of the sample 500. The secondary light beams may include PL light PL from the sample 500.

[0084] Next, as shown in step S14, the scanning unit 120 is caused to scan the spot area SA over the sample 500 by controlling the driving unit KD that moves the spot area SA over the sample 500. For example, the scanning unit 120 causes the driving unit KD to drive the galvanometer mirror X113 and the galvanometer mirror Y115.

[0085] Next, as shown in step S15, the control unit 300 executes a first observation mode to acquire a signal output by the detection unit 220 when N spot areas SA are scanned on the sample 500. In step S15, the control unit 300 acquires an illumination position, which is the position of the illumination light L10 including the N spot areas SA, and a signal output of the detection unit at the illumination position, in association with each other.

[0086] Next, as shown in step S16, the control unit 300 determines whether a predetermined observation target has been detected on the sample 500 based on the signal output in the first observation mode. In step S16, the control unit 300 may integrate signal outputs for a specific position at multiple sampling times to determine whether a predetermined observation target has been observed at a specific position on the sample 500. Here, the specific position includes the position (illumination position P3) where a predetermined defect candidate image (image G33) on the sample 500 was detected, as described above.

[0087] In step S16, if the predetermined observation target is not detected (NO), the process returns to step S14, and steps S14 to S16 are repeated. For example, the control unit 300 searches for a predetermined observation target of interest while causing the scanning unit 120 to scan. If an image appears to show something, the control unit 300 accumulates the data for predetermined sampling times t1 to t2. However, if the accumulation does not reveal anything, the process may be repeated, such as moving to another location.

[0088] If the predetermined observation target has been observed (YES) in step S16, the process proceeds to step S17. In step S17, the control unit 300 causes the separation unit 111 to switch the number of light beams of the illumination light L10 from N to M, which is equal to or greater than 1 but less than N.

[0089] Then, as shown in step S18, a second observation mode is executed in which the position where the predetermined observation target is observed is illuminated with M light beams and a signal output by the detection unit 220 is acquired. In step S18, the control unit 300 may integrate the signal outputs of the detection unit 220 when the position where the predetermined observation target is observed is illuminated at multiple sampling times. Alternatively, the control unit 300 may integrate the output signals of the detection unit 220 at a specific position.

[0090] Next, as shown in step S19, the control unit 300 determines the observation object based on the signal output in the second observation mode. In step S19, the control unit 300 may determine the content of the observation object. The content of the observation object includes, for example, discrimination of defects, particles, etc. In this way, the sample 500 can be inspected.

[0091] Next, the effects of this embodiment will be described. The inspection device 1 of this embodiment separates the illumination light L10 into N light beams and illuminates the sample 500 with the N spot areas SA. This reduces damage to the sample 500. The detection unit 220 is also provided at a position conjugate with the pupil of the condenser lens 119, and detects secondary light beams from the N spot areas SA collectively. Therefore, even if the light beam illuminating one spot area SA has an intensity that does not damage the sample 500, the overall intensity can be increased by detecting secondary light beams from the N spot areas SA. This reduces damage to the sample 500 while improving inspection accuracy.

[0092] As an example, when observing internal defects in a compound semiconductor using illumination light L10 including multiphoton excitation light, the intensity of PL light PL from linear transition semiconductors such as zinc selenide (ZnSe) and GaN is relatively high. On the other hand, the intensity of PL light PL from indirect transition semiconductors such as SiC is low. For this reason, when observing indirect transition semiconductors such as SiC, it is desirable to increase the intensity of illumination light L10 including excitation light. However, if the intensity of illumination light L10 is too high, it will damage the sample 500. On the other hand, if the intensity of illumination light L10 is not high enough to cause damage, the intensity of PL light PL will be low, resulting in an image with a lot of shot noise.

[0093] As described above, the inspection device 1 of this embodiment divides the illumination light L10 into N spot areas SA so as not to damage the sample 500, and detects secondary light rays from the N spot areas SA collectively using one detection unit 220. This makes it possible to reduce damage to the sample 500 and improve inspection accuracy by reducing noise. Furthermore, the inspection device 1 of this embodiment scans the sample 500 with the N spot areas SA, thereby improving inspection throughput.

[0094] The inspection method of this embodiment determines whether a predetermined observation target has been observed in the first observation mode, and executes the second observation mode if the predetermined observation target has been detected, thereby making the inspection more efficient.

[0095] As an example, in the first observation mode, N spot areas SA are scanned over the sample 500 so as not to damage the sample 500, searching for an interesting predetermined observation target. If such an interesting predetermined observation target is detected, the second observation mode is executed. In this way, the inspection method of this embodiment can omit observation of positions where it is determined that the predetermined observation target is not present, thereby reducing the inspection time.

[0096] Although the embodiments of the present disclosure have been described above, the present disclosure includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited to the above-described embodiments. In addition, appropriate omissions and combinations of the configurations of embodiment 1 are also within the scope of the technical concept of the present disclosure. [Explanation of symbols]

[0097] 1. Inspection equipment 100 Illumination optical system 110 Optical components 111 Separation section 112 Mirror 113 Galvano Mirror X 113a Optical elements 114a, 114b lenses 115 Galvanometer mirror Y 115a Optical elements 116a, 116b lenses 117 λ / 4 plate 118 Dichroic Mirror 119 Condenser Lens 120 Scanning unit 200 Detection optical system 210 Optical Components 211a, 211b lenses 213 Filters 220 Detector 300 control section 400 light sources 500 samples 510 Sample surface 520, 521, 522, 523 Travel route 610 Orthogonal Surface 620, 621, 622, 623 Travel route IF1, IF2, IF3 focal point KD drive unit L10 illumination light L11 light path STG Stage

Claims

1. a separation unit that separates the illumination light into a plurality of N light beams; a condenser lens that condenses the illumination light including the N light beams onto a sample to form the N spot areas on the sample; a detection unit provided at a position conjugate with a pupil of the condenser lens, the detection unit detecting secondary light rays from the N spot areas on the sample; a scanning unit that scans the spot area on the sample by controlling a driving unit that moves the spot area on the sample; a control unit that controls the separation unit to switch the number of the light beams from the N number to M number, which is 1 or more but less than N; Equipped with The control unit a first observation mode for acquiring a signal output by the detection unit when the N spot areas are scanned on the sample; determining whether a predetermined observation target is detected in the sample based on the signal output in the first observation mode; When the predetermined observation target is detected in the sample, a second observation mode is executed in which the M light beams are used to illuminate a position where the predetermined observation target is observed, and the signal output by the detection unit is acquired; determining the observation target based on the signal output in the second observation mode; Inspection equipment.

2. The control unit In the second observation mode, the signal output from the detection unit is integrated when the position where the predetermined observation object is observed is illuminated at a plurality of sampling times, thereby determining the content of the observation object. The inspection device according to claim 1 .

3. The control unit In the first observation mode, an illumination position, which is a position of the illumination light including the N spot regions, is acquired in association with the signal output of the detection unit at the illumination position; integrating the signal outputs for a specific position at a plurality of sampling times to determine whether a predetermined observation target has been observed at the specific position on the sample; The inspection device according to claim 1 .

4. the specific location includes a location where a predetermined defect candidate image on the specimen is detected; The inspection device according to claim 3 .

5. the control unit integrates the output signal of the detection unit at the specific position in the second observation mode. The inspection device according to claim 4.

6. the illumination light includes excitation light that excites the sample, the secondary light beam includes photoluminescence light from the sample; The inspection device according to claim 1 .

7. the illumination light includes multiphoton excitation light that excites the sample with a plurality of photons; The inspection device according to claim 6.

8. the interval between the adjacent spot areas is set based on the thermal conductivity of the sample. The inspection device according to claim 1 .

9. Separating the illumination light into a plurality of N light beams by a separation unit; forming the N spot areas on a sample by focusing the illumination light including the N light beams on the sample with a focusing lens; detecting secondary light rays from the N spot areas of the sample by a detection unit provided at a position conjugate with the pupil of the condenser lens; a step of causing a scanning unit to scan the spot area over the sample by controlling a driving unit that moves the spot area over the sample; executing a first observation mode to acquire a signal output by the detection unit when the N spot areas are scanned on the sample; determining whether a predetermined observation target is detected in the sample based on the signal output in the first observation mode; When the predetermined observation target is detected in the sample, switching the number of the light beams from the N to M, which is equal to or greater than 1 and less than N, by the separation unit; a step of executing a second observation mode in which the M light beams are used to illuminate a position where the predetermined observation target is observed, and the signal output by the detection unit is acquired; determining the observation target based on the signal output in the second observation mode; An inspection method comprising:

10. In the step of executing the second observation mode, integrating signal outputs of the detection unit when illuminating the position where the predetermined observation target is observed at a plurality of sampling times; In the step of determining the observation target, determining the content of the observed object; The inspection method according to claim 9.

11. In the step of executing the first observation mode, acquiring an illumination position, which is a position of the illumination light including the N spot regions, and the signal output of the detection unit at the illumination position in association with each other; integrating the signal outputs for a specific position at a plurality of sampling times to determine whether a predetermined observation target has been observed at the specific position on the sample; The inspection method according to claim 9.

12. the specific location includes a location where a predetermined defect candidate image on the specimen is detected; The inspection method according to claim 11.

13. In the step of executing the second observation mode, integrating the output signal of the detection unit at the specific position; The inspection method according to claim 12.

14. the illumination light includes excitation light that excites the sample, the secondary light beam includes photoluminescence light from the sample; The inspection method according to claim 9.

15. the illumination light includes multiphoton excitation light that excites the sample with a plurality of photons; The inspection method according to claim 14.

16. the interval between the adjacent spot areas is set based on the thermal conductivity of the sample. The inspection method according to claim 9.

Images