Inspection optical device, defect inspection device, illumination optical system, and inspection method

Abstract

The opening number setting member (39) of the first illumination optical system (30) is configured to set the illumination opening number of the first illumination light (La) in a case where the distance in the Z direction (the optical axis direction of the first illumination optical system (30)) of the substrate (WF1) from the condensing position of the first illumination light (La) is a first distance to be greater than the illumination opening number of the first illumination light (La) in a case where the distance in the Z direction of the substrate (WF1) from the condensing position of the first illumination light (La) is a second distance longer than the first distance.

Description

Technical Field

[0001] This invention relates to an optical device for inspection, a defect inspection device, an illumination optical system, and an inspection method. Background Technology

[0002] In substrate inspection apparatus, there exists a device that irradiates the surface of a substrate with laser light and detects reflected or scattered light from the laser light to inspect defects on the substrate surface (for example, see Patent Document 1). In such inspection apparatus, it is required to effectively utilize the light irradiated onto the substrate.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: US Patent No. 6,798,504 Summary of the Invention

[0006] The first invention relates to an inspection optical device for inspecting a substrate, comprising: an irradiation optical system that irradiates irradiation light toward the substrate and focuses the irradiation light into the interior of the substrate; a light-receiving optical system that receives light generated inside the substrate by the irradiation light irradiating the substrate; and a distance changing device that changes the distance in the optical axis direction of the irradiation optical system between the substrate and the focusing position of the irradiation light, wherein the irradiation optical system includes an aperture number setting member, the aperture number setting member being set such that the number of apertures of the irradiation light when the distance is a first distance is greater than the number of apertures of the irradiation light when the distance is a second distance longer than the first distance.

[0007] The second invention relates to an inspection optical device for inspecting a substrate, comprising: an irradiation optical system that irradiates irradiation light toward the substrate and focuses the irradiation light into the interior of the substrate; and a light-receiving optical system that receives light generated inside the substrate by the irradiation light irradiating the substrate, the irradiation optical system including an aperture number setting member that sets the number of apertures in such a way as to focus the irradiation light by an aperture number that satisfies the following condition.

[0008] [Number 1]

[0009] Wherein, NAi: the number of openings

[0010] nim: The refractive index of the medium between the substrate and the irradiation optical system

[0011] z: Position of the optical axis of the focal point of the illumination optical system, with the surface of the substrate facing the illumination optical system as a reference position.

[0012] λ: The wavelength of the irradiated light

[0013] f(t): a function of t, defined by the following formula when the refractive index of the substrate is set as nsa, and t = nsa / nim.

[0014] f(t)=1.068-0.006502t+3.837exp(-3.175t)

[0015] The defect inspection apparatus of the present invention includes the inspection optical device, which inspects defects in the substrate based on information about the interior of the substrate generated by the inspection optical device.

[0016] The irradiation optical system of the present invention is an irradiation optical system that irradiates an irradiation light toward a substrate and focuses the irradiation light into the interior of the substrate, and includes an aperture number setting member, which sets the number of apertures in such a way that the irradiation light is focused by an aperture number that satisfies the following condition.

[0017] [Number 2]

[0018] Wherein, NAi: the number of openings

[0019] nim: The refractive index of the medium between the substrate and the irradiation optical system

[0020] z: Position of the optical axis of the focal point of the illumination optical system, with the surface of the substrate facing the illumination optical system as a reference position.

[0021] λ: The wavelength of the irradiated light

[0022] f(t): a function of t, defined by the following formula when the refractive index of the substrate is set as nsa, and t = nsa / nim.

[0023] f(t)=1.068-0.006502t+3.837exp(-3.175t)

[0024] The first invention relates to an inspection method for a substrate, comprising: irradiating the substrate with an irradiation light and focusing the irradiation light into the interior of the substrate; receiving light generated inside the substrate by the irradiation light irradiating the substrate; and changing the distance between the substrate and the focusing position of the irradiation light in the optical axis direction of the irradiation optical system, wherein when focusing the irradiation light, the number of openings of the irradiation light when the distance is a first distance is greater than the number of openings of the irradiation light when the distance is a second distance longer than the first distance.

[0025] The second invention relates to an inspection method for a substrate, comprising: irradiating the substrate with irradiation light and focusing the irradiation light into the interior of the substrate; and receiving light generated inside the substrate by the irradiation light irradiating the substrate, wherein when focusing the irradiation light, the number of openings is set such that the irradiation light is focused according to a number of openings satisfying the following conditional expression.

[0026] [Number 3]

[0027] Wherein, NAi: the number of openings

[0028] nim: The refractive index of the medium between the substrate and the irradiation optical system

[0029] z: Position of the optical axis of the focal point of the illumination optical system, with the surface of the substrate facing the illumination optical system as a reference position.

[0030] λ: The wavelength of the irradiated light

[0031] f(t): a function of t, defined by the following formula when the refractive index of the substrate is set as nsa, and t = nsa / nim.

[0032] f(t)=1.068-0.006502t+3.837exp(-3.175t) Attached Figure Description

[0033] Figure 1 This is a schematic structural diagram showing the defect inspection device involved in the first embodiment.

[0034] Figure 2 It is a diagram used to illustrate the diameter of the first irradiating light beam.

[0035] Figure 3 This is a schematic diagram showing the relationship between the beam diameter of the first irradiation light and the aperture diameter of the object optical system.

[0036] Figure 4This is a schematic diagram showing the surface detection unit.

[0037] Figure 5 This is a schematic diagram showing the state in which the imaging position of the image of the slit opening of the second illumination light coincides with the focal position of the object optical system.

[0038] Figure 6 This is a schematic diagram showing the state in which the image of the slit opening of the second illumination light is located far from the focal position of the object's optical system.

[0039] Figure 7 This is a schematic diagram showing the image of the slit opening of the second illumination light located on the surface of the substrate.

[0040] Figure 8 This is a graph showing the relationship between the focal position and the number of apertures of the first illumination optical system when the refractive index of the substrate is 1.4.

[0041] Figure 9 This is a graph showing the relationship between the focal position and the number of apertures of the first illumination optical system when the refractive index of the substrate is 4.0.

[0042] Figure 10 The first graph shows a comparison between the function v and the peak intensity in the point image distribution function.

[0043] Figure 11 The second graph shows a comparison between the function v and the peak intensity in the point image distribution function.

[0044] Figure 12 The third chart compares the relationship between the function v and the peak intensity in the point image distribution function.

[0045] Figure 13 This is a flowchart illustrating a method for inspecting a substrate.

[0046] Figure 14 This is a schematic diagram illustrating an example where the focusing position of the first irradiation light is set inside the substrate.

[0047] Figure 15 This is a schematic structural diagram showing the defect inspection device involved in the second embodiment. Detailed Implementation

[0048] The preferred embodiments are described below. In the following description, the preferred embodiments will sometimes be... Figure 1The directions indicated by the arrows are called the X direction, Y direction, and Z direction, respectively. The X, Y, and Z directions are orthogonal to each other. The Z direction is parallel to the optical axis AX of the object optical system 36. Additionally, the coordinate position in the X direction is sometimes called the X position, the coordinate position in the Y direction is called the Y position, and the coordinate position in the Z direction is called the Z position.

[0049] [First Implementation Form]

[0050] First, the defect inspection device 1 according to the first embodiment will be described. For example... Figure 1 As shown, the defect inspection apparatus 1 according to the first embodiment includes an inspection optical device 10 and an information processing device 90. The inspection optical device 10 and the information processing device 90 are configured to transmit and receive data to each other via a network cable NW. The inspection optical device 10 is also referred to as a scanning microscope. The inspection optical device 10 includes a stage 11 on which a substrate WF1 is placed, a first light source unit 20, a first illumination optical system 30, a first light receiving part 40, a surface inspection unit 55, and an optical device control unit 80.

[0051] Stage 11 supports substrate WF1, which is the object to be inspected. Substrate WF1 may be a substrate used to manufacture power devices (power semiconductors) such as high electron mobility transistors (HEMTs). Such a substrate may, for example, contain at least one layer made of GaN (gallium nitride), a layer made of C-GaN, or a layer made of AlGaN (aluminum gallium nitride). Hereinafter, a substrate with at least one layer formed using GaN is sometimes referred to as a GaN substrate.

[0052] A stage moving part 12 is provided on the stage 11. The stage moving part 12 moves the stage 11 in the X and Y directions, which are perpendicular to the optical axis AX (Z direction) of the object optical system 36 in the first illumination optical system 30. By moving the stage 11 in the X and Y directions (directions perpendicular to the optical axis AX of the object optical system 36) using the stage moving part 12, the observation area of ​​the substrate WF1 facing the object optical system 36 can be displaced in the X and Y directions (directions along the cross-section of the substrate WF1). Furthermore, the observation area refers to a portion of the substrate WF1 scanned by the deflection scanning part 31 (described later) via the object optical system 36. The observation area can be set within a range narrower than the actual field of view of the inspection optical device 10, or it can be set within the same range as the actual field of view of the inspection optical device 10.

[0053] Furthermore, the stage moving part 12 can move the stage 11 in the direction of the optical axis AX of the object optical system 36, i.e., the Z direction. When the stage 11 is moved in the Z direction by the stage moving part 12, the relative position of the object optical system 36 with respect to the substrate WF1 supported by the stage 11 changes in the Z direction, and the focal position of the first illumination optical system 30 (the position of the focal point of the first illumination optical system 30) changes in the Z direction by the same amount as the movement of the stage 11. In addition, the focal position of the first illumination optical system 30 refers to the focusing position of the first illumination light La under the optical system design conditions. As in this embodiment, when the focusing position of the first illumination light La is located inside the substrate WF1, since the refractive index of the substrate WF1 is different from the optical system design conditions, the focal position of the first illumination optical system 30 is different from the focusing position of the first illumination light La inside the substrate WF1. Here, by varying the focal position of the first illumination optical system 30 in the Z direction, the focusing position of the first illumination light La also varies in the Z direction within the substrate WF1, thereby enabling the acquisition of images of multiple cross-sections at different Z positions (positions along the optical axis AX of the object optical system 36) within the substrate WF1. Hereafter, the direction along the optical axis AX of the object optical system 36 in the first illumination optical system 30 is sometimes referred to as the optical axis direction of the object optical system 36 or the optical axis direction of the first illumination optical system 30.

[0054] The first light source unit 20 emits a first illumination light La toward the first illumination optical system 30. The first light source unit 20 includes a first light source 21 and a light source lens 22. The first light source 21 may be, for example, a laser light source capable of emitting laser light within a specified wavelength range. The laser light emitted from the first light source 21 is shaped into parallel light by the light source lens 22 and emitted from the first light source unit 20 as the first illumination light La. The first light source 21 may be a laser light source that emits pulsed light with a pulse width of less than 1 picosecond (e.g., a pulse width in femtosecond units) (e.g., a laser light source that emits femtosecond laser light). The first light source 21 is not limited to a laser light source emitting pulsed light; it may also be a laser light source emitting continuously oscillating light. Furthermore, the first light source 21 is not limited to a laser light source; it may also be constructed using a light-emitting diode (LED) or a glow lamp.

[0055] The wavelength of the first irradiation light La is selected in the wavelength range that enables multiphoton excitation of the material constituting the substrate WF1 to cause it to emit light (e.g., the wavelength range of 700 nm to 1030 nm). For example, the wavelength of the first irradiation light La can be selected in the wavelength range that enables two-photon excitation of the material constituting the substrate WF1 to cause it to emit light. When the substrate WF1 is a GaN substrate, the wavelength of the first irradiation light La can be selected as 700 nm or 1030 nm. Regarding the two-photon excitation of GaN with laser light having a wavelength of 700 nm, it is disclosed in the literature "Tomoyuki Tanikawa et al., Three-dimensional imaging of threading dislocations in GaN crystals using two-photon excitation photoluminescence, Applied Physics Express, 11, 031004 (2018)". The use of laser light with a wavelength of 1030 nm to excite GaN in a multiphoton manner is disclosed in the literature "Mayuko Tsukakoshi et al., Identification of Burgers vectors of threading dislocations infreestanding GaN substrates via multiphoton-excitation photoluminescence mapping, Applied Physics Express, 14, 055504 (2021)".

[0056] The first illumination optical system 30 illuminates the substrate WF1 with the first illumination light La emitted from the first light source unit 20. Starting from the first light source unit 20 side, the first illumination optical system 30 sequentially includes an aperture number setting member 39, a deflection scanning unit 31, a first relay lens 32, a second relay lens 33, a first dichroic mirror 34, a second dichroic mirror 35, and an object focusing optical system 36. The object focusing optical system 36 is positioned above the stage 11. The object focusing optical system 36 faces the substrate WF1 supported by the stage 11. The object focusing optical system 36 is constructed using multiple lenses 37 and housed within a lens housing 38.

[0057] The object optical system 36 focuses the first illumination light La from the second dichroic mirror 35 (first light source unit 20). By moving the stage 11 in the Z direction using the stage moving part 12, the relative position of the object optical system 36 with respect to the substrate WF1 supported by the stage 11 is adjusted, so that the first illumination light La emitted from the object optical system 36 is focused inside the substrate WF1. That is, the positional relationship between the stage 11 and the focal point of the first illumination optical system 30, and consequently the positional relationship between the substrate WF1 and the focal point of the first illumination optical system 30, is changed. Hereinafter, the region inside the substrate WF1 where the first illumination light La is focused to the size of the resolution limit of the object optical system 36 is sometimes referred to as the illumination region 25. Furthermore, the size (diameter) of the illumination region 25 is, for example, the beam diameter of the first illumination light La, which is a laser beam (e.g., 1 / e). 2 (Diameter). The resolution limit of the object optical system 36 is equivalent to the radius of the first dark ring of the so-called Airy disk. When the size (diameter) of the illumination region 25 is smaller than the diameter of the first dark ring of the Airy disk, the first illumination light La is said to be focused to the resolution limit.

[0058] In addition, Figure 1 In this example, the object optical system 36 is constructed using four lenses 37, but it is not limited to this. For example, the object optical system 36 can be constructed using five or more lenses, or it can be constructed using two or three lenses. In addition, at least a portion of the multiple lenses 37 can be configured to move in the optical axis direction of the object optical system 36 by rotating a correction ring (not shown) provided in the lens frame 38. Furthermore, instead of using the stage moving part 12 to move the stage 11 in the Z direction, or in addition to using the stage moving part 12 to move the stage 11 in the Z direction, the object optical system 36 can also be moved in the Z direction (optical axis direction) by a distance changing device (not shown), thereby changing the focal position of the first illumination optical system 30 in the Z direction inside the substrate WF1.

[0059] Furthermore, one or more optical components constituting the first illumination optical system 30 can be moved to change the focal position of the first illumination optical system 30 in the Z direction. Alternatively, one or more optical components constituting the first illumination optical system 30 can be used as optical elements with variable focal distances to change the focal position of the first illumination optical system 30 in the Z direction. In this case, the moving mechanism that moves one or more optical components can be called a distance changing device, and the optical element with a variable focal distance can also be called a distance changing device. In addition, the stage moving part 12 can also be called a distance changing device that changes the distance in the Z direction (optical axis direction of the first illumination optical system 30) between the substrate WF1 and the focusing position of the first illumination light La.

[0060] The deflection scanning unit 31 scans the interior of the substrate WF1 in both the X and Y directions using the first illumination light La from the first light source unit 20. The deflection scanning unit 31 is equipped with an X-direction deflector 31a and a Y-direction deflector 31b, which can change the propagation direction of the first illumination light La. The X-direction deflector 31a and the Y-direction deflector 31b are constructed using galvanometer mirrors, micro-electro-mechanical systems (MEMS) mirrors, resonant mirrors (resonant type mirrors), etc. The X-direction deflector 31a and the Y-direction deflector 31b are positioned at or near the conjugate surface of the pupil plane Pp of the object optical system 36. Hereinafter, the conjugate surface of the pupil plane Pp of the object optical system 36 is sometimes referred to as the pupil conjugate surface.

[0061] By oscillating or rotating the X-direction deflector 31a in the rotational direction (θy direction) centered on the Y-axis, the propagation direction of the first irradiation light La changes in the θy direction around the Y-axis, and the irradiation area 25 in the substrate WF1 moves in the X direction. By oscillating or rotating the Y-direction deflector 31b in the rotational direction (θx direction) centered on the X-axis, the propagation direction of the first irradiation light La changes in the θx direction around the X-axis, and the irradiation area 25 in the substrate WF1 moves in the Y direction. Therefore, by oscillating or rotating the X-direction deflector 31a and the Y-direction deflector 31b, the deflection scanning unit 31 moves the irradiation area 25 in the substrate WF1 in both the X and Y directions (XY directions), thereby enabling two-dimensional scanning of the interior of the substrate WF1.

[0062] Between the first relay lens 32 and the second relay lens 33, an intermediate image plane Im conjugate to the substrate WF1 (object surface) is formed. The first relay lens 32 focuses the first illumination light La from the deflecting scanning section 31 onto the intermediate image plane Im. The second relay lens 33 converts the first illumination light La from the first relay lens 32 into parallel light and guides it to the object focusing optical system 36 (first dichroic mirror 34). Furthermore, the first relay lens 32 and the second relay lens 33 are not limited to a single lens, but can be constructed using multiple lenses. The first relay lens 32 can also be called a scanning lens. The second relay lens 33 can also be called an imaging lens or a second object focusing lens.

[0063] The first dichroic mirror 34 may, for example, have the characteristic of reflecting blue light or light in a wavelength range shorter than blue light, and allowing light in a wavelength range longer than blue light to pass through. The first dichroic mirror 34 is not limited to the aforementioned wavelength characteristics; it only needs to have the characteristic of reflecting light generated inside the substrate WF1 through multiphoton excitation, and allowing the first illumination light La from the first light source unit 20, which has passed through the second relay lens 33, to pass through. Hereinafter, the light generated inside the substrate WF1 through multiphoton excitation is sometimes referred to as the detection light Ld.

[0064] The second dichroic mirror 35 may, for example, have the following characteristics: it reflects light in the wavelength range of green light, and allows light in the wavelength range longer than green light and light in the wavelength range shorter than green light to pass through. The second dichroic mirror 35 is not limited to the wavelength characteristics mentioned above, as long as it has the following characteristics: it reflects the second illumination light Lb (and the reflected light Le described later) from the surface detection unit 55, and allows the first illumination light La from the first dichroic mirror 34 and the detection light Ld from the object optical system 36 to pass through.

[0065] The aperture number setting member 39 is configured, for example, using a zoom beam expander. The aperture number setting member 39 sets the angle of the first illumination light La, which is focused into the substrate WF1 by the first illumination optical system 30, by changing the beam diameter of the first illumination light La emitted from the first light source unit 20. The angle of the first illumination light La refers to the maximum angle of the first illumination light La focused by the first illumination optical system 30 (object optical system 36) relative to the optical axis AX of the object optical system 36. Furthermore, the value obtained by multiplying the sine of the angle of the first illumination light La by the refractive index of the medium between the substrate WF1 and the first illumination optical system 30 is called the number of illumination apertures for the first illumination light La. In other words, the aperture number setting member 39 can set the number of illumination apertures for the first illumination light La, which is focused into the substrate WF1 by the first illumination optical system 30, by changing the beam diameter of the first illumination light La emitted from the first light source unit 20.

[0066] The number of illumination openings of the first illumination light La (the value obtained by multiplying the sine of the angle of the first illumination light La by the refractive index of the medium between the substrate WF1 and the first illumination optical system 30) can be determined based on the beam diameter of the first illumination light La in the pupil plane Pp of the object optical system 36, as shown in the following formula (A).

[0067] NAi=nim×Da / 2f …(A)

[0068] Where Ni is the number of illumination openings in the first illumination light La.

[0069] nim: The refractive index of the medium between the substrate WF1 and the first illumination optical system 30

[0070] Da: The beam diameter of the first irradiation light La in the pupil plane Pp of the object optical system 36.

[0071] f: Focal distance of the object optical system 36

[0072] Figure 2 This is a diagram used to illustrate the beam diameter of the first irradiating light La. Figure 2 The horizontal axis of the graph shown represents the radial position R of the first irradiation light La. Figure 2 The vertical axis of the graph shown represents the beam intensity K of the first irradiating light La. For example... Figure 2 As shown, when the first illumination light La is a Gaussian beam, the beam diameter Da of the first illumination light La in the pupil plane Pp of the object optical system 36 refers to the beam intensity Da when the beam intensity K of the first illumination light La is averaged over the circumferential direction, which is 1 / e of the peak intensity. 2 The following diameters. Furthermore, such as... Figure 2 As shown by the double-dotted line, even when the beam intensity decreases to 1 / e of the peak intensity... 2 If the outer periphery of the first illumination beam La is blocked, the beam intensity K of the first illumination beam La at the blocked position (the position reduced to zero) will also decrease to 1 / e of the peak intensity. 2 Therefore, in cases where the outer periphery of the first irradiation light La is blocked, including the case where the first irradiation light La is a flat-top beam, the beam diameter Da# becomes "the beam intensity becomes 1 / e of the peak intensity". 2 The following diameters.

[0073] Furthermore, the sine of the angle subtended by the detection light Ld is based on the aperture diameter Dd in the pupil plane Pp of the object optical system 36 (refer to...). Figure 3 The angle of the detection light Ld is determined by the first light-receiving unit 40 (object optical system 36) and is the maximum angle relative to the optical axis AX of the object optical system 36. The value obtained by multiplying the sine of the angle of the detection light Ld by the refractive index of the medium between the substrate WF1 and the first illumination optical system 30 is called the number of detection apertures of the detection light Ld, or the number of apertures of the object optical system 36. The number of detection apertures of the detection light Ld (the value obtained by multiplying the sine of the angle of the detection light Ld by the refractive index of the medium between the substrate WF1 and the first illumination optical system 30) can be determined based on the aperture diameter Dd in the pupil plane Pp of the object optical system 36, as shown in the following formula (B).

[0074] NAd=nim×Dd / 2f …(B)

[0075] Wherein, NAd: the number of detection openings in the detection light Ld.

[0076] nim: The refractive index of the medium between the substrate WF1 and the first illumination optical system 30

[0077] Dd: The beam diameter of the first irradiation light La in the pupil plane Pp of the object optical system 36.

[0078] f: Focal distance of the object optical system 36

[0079] The ratio of the number of illumination openings of the first illumination light La to the number of detection openings of the detection light Ld is defined as σ. The number of illumination openings of the first illumination light La can be less than the number of detection openings of the detection light Ld. That is, σ can be less than 1. In other words, the beam diameter Da of the first illumination light La in the pupil plane Pp of the object optical system 36 can be less than the opening diameter Dd in the pupil plane Pp of the object optical system 36. As a result, more detection light Ld generated inside the substrate WF1 by multiphoton excitation can be received by the first light-receiving part 40 (object optical system 36). Furthermore, σ can be 0.9, 0.80, or 0.70.

[0080] Back Figure 1 The first light-receiving section 40 includes a first light-receiving optical system 41 and a first detector 51. The first light-receiving optical system 41 receives detection light Ld generated inside the substrate WF1 (irradiation area 25) by multiphoton excitation caused by the first irradiation light La. The first light-receiving optical system 41 includes an object-oriented optical system 36 of the first irradiation optical system 30, a second dichroic mirror 35, and a first dichroic mirror 34. Furthermore, the first light-receiving optical system 41 includes a third relay lens 42 and a suppression filter 43 sequentially from the first dichroic mirror 34 side (substrate WF1 side).

[0081] The third relay lens 42 guides the detection light Ld reflected by the first dichroic mirror 34 to the pupil conjugate surface of the object optical system 36. Furthermore, the third relay lens 42 is not limited to two lenses; it can also be constructed using three or more lenses. The suppression filter 43 has the characteristic of allowing light (specifically, the detection light Ld) in a predetermined wavelength range from the first dichroic mirror 34 (third relay lens 42) to pass through. The suppression filter 43, for example, blocks at least a portion of the first illumination light La reflected by the substrate WF1, external light, stray light, etc. Furthermore, the suppression filter 43 is also referred to as a bandpass filter.

[0082] The first detector 51 is constructed using, for example, a photomultiplier tube, a photodiode, or an avalanche photodiode. A detection surface 52 is formed on or near the pupil conjugate surface of the object focusing optical system 36. The first detector 51 receives light (detection light Ld) emitted from the illumination region 25 inside the substrate WF1 that passes through the third relay lens 42 and the suppression filter 43 of the first light-receiving optical system 41 and is incident on the detection surface 52. It then performs photoelectric conversion and outputs a light-receiving signal (also called a detection signal) from the illumination region 25 inside the substrate WF1. Hereinafter, the light-receiving signal output from the first detector 51 is sometimes referred to as the first light-receiving signal.

[0083] Surface detection unit 55 Figure 4 As shown, the device includes a second light source 60, a second illumination optical system 61, and a second light-receiving part 70. Furthermore, the surface inspection unit 55 includes a second dichroic mirror 35 and an object-oriented optical system 36 of the first illumination optical system 30. However, the defect inspection device 1 (inspection optical device 10) may not include the surface inspection unit 55. The second light source 60 emits a second illumination light Lb toward the second illumination optical system 61. The second light source 60 is constructed, for example, using an LED. Alternatively, the second light source 60 is not limited to LEDs and may also be constructed using a laser light source. The wavelength of the second illumination light Lb is selected within the wavelength range that the second dichroic mirror 35 can reflect (e.g., the wavelength range of green light). Additionally, the wavelength of the second illumination light Lb can be selected within the wavelength range that is reflectable on the surface of the substrate WF1, or within the wavelength range that is reflectable at the interfaces of multiple layers of the substrate WF1.

[0084] The second illumination optical system 61 emits the second illumination light Lb emitted from the second light source 60 toward the surface of the substrate WF1. Simultaneously, the second illumination optical system 61 illuminates the surface of the substrate WF1 with the second illumination light Lb directed in a direction inclined relative to the optical axis AX of the object optical system 36. The second illumination optical system 61, starting from the second light source 60 side, sequentially includes a first condenser lens 62, a slit plate 63, a second condenser lens 64, a first pupil limiting mask 65, a semi-reflective mirror 66, a focal position adjusting lens 67, and a bandpass filter 68.

[0085] The first focusing lens 62 focuses the second illumination light Lb emitted from the second light source 60. The slit plate 63 is positioned conjugate to the substrate WF1 (object surface). A slit opening 63a is formed in the center of the slit plate 63. The slit opening 63a is formed as a rectangular opening with its long side extending in the Y direction (perpendicular to the optical axis of the second illumination optical system 61). Furthermore, the second illumination light Lb passing through the slit opening 63a becomes light with a rectangular cross-section. The second focusing lens 64 guides the second illumination light Lb passing through the slit opening 63a to the first pupil limiting mask 65.

[0086] A first pupil limiting mask 65 is disposed at the pupil position in the second illumination optical system 61, blocking half of the pupil. Furthermore, the first pupil limiting mask 65 is configured to block half of the region bounded by the center line of the long side of the rectangular cross-section of the second illumination light Lb. A semi-reflective mirror 66 allows a portion of the second illumination light Lb that has passed through the first pupil limiting mask 65 to pass through. Additionally, the semi-reflective mirror 66 reflects a portion of the second illumination light Lb reflected from the surface of the substrate WF1 and transmitted through the focal position adjustment lens 67 towards the second light-receiving part 70 (second light-receiving optical system 71) and its second objective lens 72. The transmittance to reflectance ratio of the semi-reflective mirror 66 is, for example, set to 1:1. Hereinafter, the second illumination light Lb reflected from the surface of the substrate WF1 is sometimes referred to as reflected light Le.

[0087] The focal position adjusting lens 67 has a convex lens 67a and a concave lens 67b. It is configured such that one of the convex lens 67a and the concave lens 67b is fixed on the optical axis, while the other is movable along the optical axis. Alternatively, it can be configured such that both the convex lens 67a and the concave lens 67b are movable along the optical axis. In the following description, the case where the convex lens 67a is fixed on the optical axis and the concave lens 67b is movable along the optical axis will be explained. A lens moving part 69 is provided in the focal position adjusting lens 67. The lens moving part 69 is configured with a focal position adjusting lens motor (not shown) capable of driving the concave lens 67b of the focal position adjusting lens 67. The lens moving part 69 moves the concave lens 67b of the focal position adjusting lens 67 along the optical axis. Furthermore, the convex lens 67a can be a lens group containing multiple lenses and having a positive magnification overall, and the concave lens 67b can be a lens group containing multiple lenses and having a negative magnification overall. In this case, the lens moving part 69 can move one or more lenses in these lens groups along the optical axis.

[0088] Furthermore, when multiple focal position adjustment lenses 67 with different magnifications are provided, the lens moving unit 69 may have an electric turret (not shown) for the focal position adjustment lens. In this case, the electric turret for the focal position adjustment lens of the lens moving unit 69 selects any one of the multiple focal position adjustment lenses 67 and arranges it in the optical path between the semi-reflective mirror 66 and the bandpass filter 68, for example, according to the operation of the focal position switching operation switch (not shown) provided in the inspection optical device 10 or the information processing device 90.

[0089] A bandpass filter 68 is disposed in the optical path between the focal position adjustment lens 67 and the second dichroic mirror 35. The bandpass filter 68, for example, has the characteristic of allowing light in the green wavelength range (specifically, the second illumination light Lb and the reflected light Le) to pass through. The bandpass filter 68, for example, blocks at least a portion of the detection light Ld reflected by the second dichroic mirror 35, external light, stray light, etc.

[0090] The second light-receiving section 70 includes a second light-receiving optical system 71 and a second detector 78. The second light-receiving optical system 71 receives reflected light Le from the surface of the substrate WF1, which has been irradiated by the second irradiation light Lb, and focuses it onto the second detector 78. The second light-receiving optical system 71 includes a bandpass filter 68, a focal position adjustment lens 67, and a semi-reflective mirror 66 of the second irradiation optical system 61. Furthermore, the second light-receiving optical system 71 includes, in sequence from the semi-reflective mirror 66 side (substrate WF1 side), a second object lens 72 for light reception, a first relay lens 73 for light reception, a second pupil limiting mask 74, a second relay lens 75 for light reception, and a cylindrical lens 76.

[0091] The second objective lens 72 for receiving light focuses the reflected light Le reflected by the half-reflecting mirror 66. The first relay lens 73 for receiving light guides the reflected light Le from the second objective lens 72 to the second pupil limiting mask 74. The second pupil limiting mask 74 is positioned at the pupil position in the second light-receiving optical system 71, blocking half of the pupil. The area blocked by the second pupil limiting mask 74 corresponds to the area blocked by the first pupil limiting mask 65. Thus, the reflected light Le from the first relay lens 73 can pass through the second pupil limiting mask 74. The second relay lens 75 for receiving light focuses the reflected light Le that has passed through the second pupil limiting mask 74 toward the detection surface 79 of the second detector 78. The cylindrical lens 76 compresses the reflected light Le focused by the second relay lens 75 in the long side direction (Y direction) of the rectangular cross-section, forming an image of the slit opening 63a on the detection surface 79 of the second detector 78.

[0092] The second detector 78 is configured, for example, using a line sensor. The second detector 78 has a detection surface 79 having a plurality of detection pixels (not shown) arranged in a one-dimensional direction (e.g., the X direction, the direction of the short side of the image of the slit opening 63a). On the detection surface 79 of the second detector 78, reflected light Le (second illumination light Lb reflected from the surface of the substrate WF1) from the second light-receiving optical system 71 is focused to form an image of the slit opening 63a. The second detector 78 receives the image of the slit opening 63a formed on the detection surface 79 and performs photoelectric conversion, outputting a light-receiving signal (also called a detection signal) of the image of the slit opening 63a. Alternatively, the second detector 78 may also be configured using a two-dimensional image sensor. Hereinafter, the light-receiving signal output from the second detector 78 will sometimes be referred to as the second light-receiving signal.

[0093] The optical device control unit 80 is configured using, for example, a central processing unit (CPU). The optical device control unit 80 includes an interface unit 81, a storage unit 85, a data acquisition unit 86, and an image processing unit 87. Based on the control program stored in the storage unit 85, the optical device control unit 80 controls the operation of the stage movement unit 12, the first light source unit 20 (first light source 21), the deflection scanning unit 31, the aperture number setting member 39, the surface detection unit 55 (second light source 60, lens movement unit 69), etc.

[0094] Interface 81 is electrically connected to one end of network cable NW. The other end of network cable NW is electrically connected to interface 91 of information processing device 90. Interface 81 of optical device control unit 80 receives setting information on the focusing position of first illumination light La transmitted from interface 91 of information processing device 90 via network cable NW, and information about the structure of substrate WF1. The setting information on the focusing position of first illumination light La and the information about the structure of substrate WF1 input to interface 81 are stored in storage unit 85. Hereinafter, the information about the structure of substrate WF1 is sometimes referred to as substrate structure information.

[0095] The focusing position of the first illumination light La is the focusing position of the first illumination light La offset relative to the surface of the substrate WF1 in the Z direction (optical axis direction of the object optical system 36). The setting information of the focusing position of the first illumination light La is set according to the Z position of the cross-sectional portion inspected inside the substrate WF1. In addition, the setting information of the focusing position of the first illumination light La may include information about the wavelength of the first illumination light La.

[0096] The substrate structure information may include information about the thickness of the substrate WF1 or information about the refractive index of the substrate WF1. Furthermore, the refractive index of the substrate WF1 is the refractive index relative to the wavelength of the first irradiation light La. If the first irradiation light La is light with a wavelength width, the refractive index of the substrate WF1 may be the refractive index relative to the center wavelength of the first irradiation light La. Alternatively, in this case, the refractive index of the substrate WF1 may be the refractive index relative to one or more wavelengths within the wavelength width of the first irradiation light La. The substrate structure information may include information about multiple layers in the substrate WF1. Additionally, the substrate structure information may also include information about the refractive index of the medium between the substrate WF1 and the first irradiation optical system 30. The medium between the substrate WF1 and the first irradiation optical system 30 may be, for example, air, a gas such as nitrogen, or a liquid such as water or oil.

[0097] The data acquisition unit 86 acquires the first light-receiving signal output from the first detector 51. Furthermore, the optical device control unit 80 synchronizes with the scanning performed inside the substrate WF1 by moving the irradiation area 25 in both the X and Y directions (XY directions) via the bias scanning unit 31, causing the data acquisition unit 86 to acquire the first light-receiving signal. Based on the first light-receiving signal acquired by the data acquisition unit 86 and output from the first detector 51, the image processing unit 87 generates image data of a cross-section in the XY direction (a direction perpendicular to the thickness direction of the substrate WF1) inside the substrate WF1.

[0098] Additionally, the data acquisition unit 86 acquires the second light-receiving signal output from the second detector 78. The optical device control unit 80 performs autofocus control (described later) based on the second light-receiving signal acquired by the data acquisition unit 86 and output from the second detector 78. The calculation unit 88 calculates the control signal output to the stage movement unit 12 in the autofocus control. Furthermore, the calculation unit 88 calculates the control signal output to the aperture number setting member 39.

[0099] The information processing device 90 is configured, for example, using a personal computer (PC). The information processing device 90 includes an interface unit 91, an input unit 92, a display unit 93, an input / output control unit 94, a storage unit 95, and a determination unit 96. The interface unit 91 is electrically connected to the other end of a network cable NW. Image data from inside the substrate WF1, transmitted via the network cable NW from the interface unit 81 of the inspection optical device 10 (optical device control unit 80), is input to the interface unit 90. The image data input to the interface unit 91 from inside the substrate WF1 is stored in the storage unit 95.

[0100] The input unit 92 is a user-operable input interface. The input unit 92 may be configured using at least one of a mouse, keyboard, touchpad, trackball, etc. The input unit 92 detects user operations and outputs the detection results as user input information to the input / output control unit 94. The input unit 92 may input setting information for the focusing position of the first illumination light La, or information about the substrate structure.

[0101] The display unit 93 is configured, for example, using a liquid crystal display (LCD). The input / output control unit 94 causes the display unit 93 to display the graphical user interface (GUI) required for the operation of the inspection optical device 10, the image of the interior of the substrate WF1 sent from the inspection optical device 10 (optical device control unit 80), the determination result of the determination unit 96 on whether there are defects inside the substrate WF1, etc. The input / output control unit 94 sends, for example, the setting information of the focusing position of the first irradiation light La and the substrate structure information input from the input unit 92 to the optical device control unit 80 of the inspection optical device 10 from the interface unit 91.

[0102] The determination unit 96 determines whether a defect exists inside the substrate WF1 based on image data of the substrate WF1 stored in the storage unit 95. Furthermore, if a defect (e.g., a crystal defect) exists inside the substrate WF1, the defective portion inside the substrate WF1 is less likely to generate multiphoton excitation caused by the first irradiation light La, and therefore the defective portion will appear darker in the image inside the substrate WF1. Therefore, the determination unit 96 may also consider portions of the image inside the substrate WF1 with brightness values ​​(tone values) below a predetermined threshold as defective portions to determine whether a defect exists inside the substrate WF1. The determination result of whether a defect exists inside the substrate WF1, as determined by the determination unit 96, is stored in the storage unit 95.

[0103] In the defect inspection apparatus 1 configured as described above, when inspecting the substrate WF1, the interface 81 of the inspection optical device 10 inputs setting information of the focusing position of the first irradiation light La, which is sent from the interface 91 of the information processing device 90, and substrate structure information. The input setting information of the focusing position of the first irradiation light La and substrate structure information are stored in the storage 85 of the optical device control unit 80. The optical device control unit 80 controls the lens movement unit 69 of the surface detection unit 55 so that the first irradiation light La is focused at the focusing position inside the substrate WF1.

[0104] Here, refer to Figures 5-7 The function of the focal position adjusting lens 67, driven by the lens moving part 69, will be explained. Furthermore, in Figures 5-7 The diagram only shows the components required for illustration. For example... Figure 5As shown, when the concave lens 67b of the focal position adjusting lens 67 is moved to a predetermined proximity position close to the convex lens 67a by the lens moving part 69, the imaging position PS of the image of the second illumination light Lb irradiated from the object optical system 36 through the slit opening 63a coincides with the focal position PF of the object optical system 36. Furthermore, in this case, the second illumination light Lb becomes parallel light before and after the focal position adjusting lens 67. In this state, when the optical device control unit 80 performs the autofocus control described later, the focal position PF of the object optical system 36 is located on the surface of the substrate WF1.

[0105] like Figure 6 As shown, when the concave lens 67b of the focal position adjusting lens 67 is moved a distance x away from the convex lens 67a by the lens moving part 69, the imaging position PS of the image of the slit opening 63a of the second irradiation light Lb moves a predetermined distance (also called offset L) from the focal position PF of the object optical system 36 toward the direction closer to the object optical system 36 (-Z direction). In this state, when the optical device control unit 80 performs the autofocus control described later, the stage 11 is moved in the -Z direction by the stage moving part 12, and the surface of the substrate WF1 moves in the -Z direction at the same time, as shown. Figure 7 As shown, the imaging position PS of the image of the second illumination light Lb through the slit opening 63a is located on the surface of the substrate WF1. Therefore, the focal position PF of the object optical system 36 is located inside the substrate WF1, enabling the first illumination light La emitted from the object optical system 36 to be focused inside the substrate WF1. Furthermore, it can also be said that the imaging position PS of the image of the second illumination light Lb through the slit opening 63a is the focusing position of the second illumination light Lb.

[0106] [Autofocus control]

[0107] Next, the autofocus control performed by the optical device control unit 80 using the surface detection unit 55 will be explained. For example... Figure 4 As shown, the second illumination light Lb emitted from the second light source 60 of the surface detection unit 55 is incident on the second illumination optical system 61. The second illumination light Lb incident on the second illumination optical system 61 is focused by the first condenser lens 62 and passes through the slit opening 63a of the slit plate 63. The second illumination light Lb passing through the slit opening 63a passes through the second condenser lens 64 and passes through the first pupil limiting mask 65. A portion of the second illumination light Lb passing through the first pupil limiting mask 65 passes through the semi-reflective mirror 66 and is incident on the focal position adjustment lens 67. The second illumination light Lb passing through the focal position adjustment lens 67 passes through the bandpass filter 68 and is reflected by the second dichroic mirror 35. The second illumination light Lb reflected by the second dichroic mirror 35 is irradiated towards the substrate WF1 by the object optical system 36 and is focused.

[0108] The second illumination light Lb, emanating from the object optical system 36 and directed towards the substrate WF1, is reflected from the surface of the substrate WF1 and re-enters the object optical system 36. The reflected light Le (the second illumination light Lb) from the surface of the substrate WF1, incident on the object optical system 36, passes through the object optical system 36 and is reflected by the second dichroic mirror 35. The reflected light Le, reflected by the second dichroic mirror 35, passes through the bandpass filter 68 and enters the focal position adjustment lens 67. A portion of the reflected light Le that has passed through the focal position adjustment lens 67 is reflected by the semi-reflective mirror 66. The reflected light Le, reflected by the semi-reflective mirror 66, is focused by the second object lens 72 of the second light-receiving optical system 71. The reflected light Le focused by the second object lens 72 passes through the first relay lens 73 and through the second pupil limiting mask 74. The reflected light Le that has passed through the second pupil limiting mask 74 passes through the second relay lens 75 and the cylindrical lens 76. The reflected light Le, which passes through the cylindrical lens 76, is focused and reaches the detection surface 79 of the second detector 78. The second detector 78 receives the image of the slit opening 63a formed on the detection surface 79 and performs photoelectric conversion, outputting a second light-receiving signal.

[0109] Furthermore, when the Z position of the surface of substrate WF1 changes, the reflection position of the second illumination light Lb on the surface of substrate WF1 changes because the distance between the surface of substrate WF1 and the object optical system 36 changes. When the reflection position of the second illumination light Lb on the surface of substrate WF1 changes, the position of the image of the slit opening 63a formed on the detection surface 79 of the second detector 78 changes in the extending direction of the detection surface 79 (the direction of the short side of the image of the slit opening 63a). Therefore, based on the second light-receiving signal output from the second detector 78, the imaging position (focusing position of the second illumination light Lb) of the image of the slit opening 63a on the surface of substrate WF1 relative to the optical axis of the object optical system 36 can be determined.

[0110] The second light-receiving signal output from the second detector 78 is acquired by the data acquisition unit 86. Based on the second light-receiving signal acquired by the data acquisition unit 86, the calculation unit 88 calculates a control signal for autofocus control to control the stage movement unit 12, such that the imaging position of the image at the slit opening 63a (the focusing position of the second illumination light Lb) is located on the surface of the substrate WF1. The optical device control unit 80 outputs the autofocus control signal calculated by the calculation unit 88 to the stage movement unit 12, thereby controlling the stage movement unit 12. Alternatively, the calculation unit 88 may, for example, calculate the autofocus control signal based on the result of scanning the second light-receiving signals output from multiple detection pixels (not shown) of the second detector 78 along the detection surface 79, as disclosed in U.S. Patent No. 7,071,451.

[0111] When the first illumination light La is focused inside the substrate WF1, aberrations occur in the layer between the focusing position of the first illumination light La and the surface of the substrate WF1. Hereinafter, the aberrations occurring in the layer between the focusing position of the first illumination light La and the surface of the substrate WF1 are sometimes referred to as refractive index mismatch aberrations. The longer the distance in the Z direction (optical axis direction of the first illumination optical system 30) from the surface of the substrate WF1 to the focusing position of the first illumination light La inside the substrate WF1, the greater the refractive index mismatch aberration. As a result, the component of the first illumination light La with a large angle relative to the optical axis AX of the object optical system 36 no longer focuses, leading to a decrease in the utilization efficiency of the first illumination light La.

[0112] Therefore, the aperture number setting member 39 of the first illumination optical system 30 is set such that the longer the distance in the Z direction from the surface of the substrate WF1 to the focusing position of the first illumination light La inside the substrate WF1, the smaller the number of illumination apertures of the first illumination light La. For example, the aperture number setting member 39 is set such that the number of illumination apertures of the first illumination light La when the distance in the Z direction between the substrate WF1 and the focusing position of the first illumination light La is a first distance is greater than the number of illumination apertures of the first illumination light La when the distance in the Z direction between the substrate WF1 and the focusing position of the first illumination light La is a second distance longer than the first distance.

[0113] In addition, the number of openings setting member 39 can also set the number of lighting openings of the first irradiation light La in such a way that the number of lighting openings satisfies the following condition (1) to focus the first irradiation light La.

[0114] [Number 4] …(1) Where Ni is the number of illumination openings in the first illumination light La. nim: The refractive index of the medium between the substrate WF1 and the first illumination optical system 30 z: The position of the optical axis direction of the focal point of the first illumination optical system 30 (object optical system 36), with the surface of the substrate WF1 facing the first illumination optical system 30 (object optical system 36) as the reference position. λ: Wavelength of the first illumination light La f(t): a function of t, defined by the following formula when the refractive index of substrate WF1 is set to nsa, and t = nsa / nim. f(t)=1.068-0.006502t+3.837exp(-3.175t) Figure 8 The relationship between the focusing position of the first irradiation light La and the number of apertures is shown when the refractive index nsa = 1.4 of the substrate WF1. Figure 8 The horizontal axis of the graph shown represents the logarithmic function of z / λ with a base of 10. Figure 8 The vertical axis of the chart shown represents the number of openings, NA. Additionally, Figure 9 The relationship between the focusing position of the first irradiation light La and the number of apertures is shown when the refractive index nsa = 4.0 of the substrate WF1. Figure 9 The horizontal and vertical axes of the chart shown are... Figure 8 The horizontal and vertical axes of the chart shown are the same.

[0115] from Figure 8 as well as Figure 9 It can be seen that, regardless of whether the refractive index of substrate WF1 is nsa=1.4 or nsa=4.0, the optimal number of illumination apertures NAg when the first illumination light La is a Gaussian beam decreases as the focusing position of the first illumination light La moves further away from the surface of substrate WF1. Furthermore, the optimal number of illumination apertures NAg when the first illumination light La is a flat-top beam also decreases as the focusing position of the first illumination light La moves further away from the surface of substrate WF1. Figure 8 as well as Figure 9 In the diagram, a single-dotted line indicates the effective range (upper and lower limits) of the number of openings NA2 under two-photon excitation. A dashed line indicates the effective range (upper and lower limits) of the number of openings NA3 under three-photon excitation.

[0116] Here, the function v is defined as follows (2):

[0117] [Number 5] …(2) In the case of -0.05 < v < 0.05, it is the same as the condition (1).

[0118] Figure 10 The relationship between the function v at t=1.4 and the peak intensity in the point spread function (PSF) is shown by comparing them. Figure 10 The horizontal axis of the graph shown represents the value of the function v. Figure 10 The vertical axis of the graphs shown represents the peak intensity in the point image distribution function (PSF) during two-photon excitation for nim×z / λ=10, nim×z / λ=100, and nim×z / λ=500, respectively. Figure 11 The relationship between the function v at t=2.4 and the peak intensity in the point image distribution function (PSF) is shown by comparing them. Figure 11 The horizontal and vertical axes of the chart shown are... Figure 10 The horizontal and vertical axes of the chart shown are the same. Figure 12The relationship between the function v at t=3.8 and the peak intensity in the point image distribution function (PSF) is shown by comparing them. Figure 12 The horizontal and vertical axes of the chart shown are... Figure 10 The horizontal and vertical axes of the chart shown are the same.

[0119] from Figures 10-12 It can be seen that within the range of -0.05 < v < 0.05, even if the number of illumination apertures NAI of the first illumination light La is changed to alter the value of the function v, the peak intensity in the point image distribution function (PSF) during two-photon excitation will still reach approximately 80% or more of the optimal value. Thus, by satisfying condition (1), the peak intensity in the point image distribution function (PSF) during multiphoton excitation can be increased, thereby enabling the number of illumination apertures of the first illumination light La to be set within a suitable range.

[0120] [Inspection methods for substrates]

[0121] Next, the inspection method for the substrate WF1 using the defect inspection apparatus 1 of the first embodiment will be summarized. Figure 13 This is a flowchart illustrating the inspection method for substrate WF1. (Example) Figure 13 As shown, firstly, based on the setting information of the focusing position of the first irradiation light La and the substrate structure information stored in the storage unit 85, the defect inspection device 1 is set (step ST10). At this time, the calculation unit 88 calculates the control signal for controlling the aperture number setting member 39 of the first irradiation optical system 30, so as to set the number of illumination apertures of the first irradiation light La that satisfies the condition (1). The optical device control unit 80 outputs the control signal calculated by the calculation unit 88 to the aperture number setting member 39, thereby controlling the aperture number setting member 39. Under the control of the optical device control unit 80, the aperture number setting member 39 sets the number of illumination apertures of the first irradiation light La in a manner that satisfies the condition (1). In addition, the aperture number setting member 39 is set such that the longer the distance in the Z direction from the surface of the substrate WF1 to the focusing position of the first irradiation light La inside the substrate WF1, the smaller the number of illumination apertures of the first irradiation light La.

[0122] At this time, the calculation unit 88 calculates the offset L of the focusing position of the second irradiation light Lb relative to the focusing position of the first irradiation light La. When calculating the offset L, the calculation unit 88 can also adjust the focusing position of the first irradiation light La to correct the refractive index mismatch aberration generated in the substrate WF1. For example, the calculation unit 88 can also calculate the offset L based on a focusing position adjustment data table prepared in advance through optical simulation, according to the focusing position of the first irradiation light La set inside the substrate WF1 (depth from the surface of the substrate WF1).

[0123] The optical device control unit 80 outputs a control signal to the lens moving unit 69 of the surface detection unit 55, which can obtain the offset L calculated by the calculation unit 88. The lens moving unit 69 moves the concave lens 67b of the focal position adjusting lens 67 according to the control signal output from the optical device control unit 80. As a result, the focusing position of the second illumination light Lb irradiated from the object optical system 36 (the imaging position of the image of the slit opening 63a of the second illumination light Lb) moves by an offset L relative to the focusing position of the first illumination light La irradiated from the object optical system 36. In this state, by performing autofocus control by the optical device control unit 80, the focusing position of the first illumination light La irradiated from the object optical system 36 can be made to coincide with the focusing position of the first illumination light La set inside the substrate WF1.

[0124] Next, the first illumination light La is irradiated toward the substrate WF1, and the first illumination light La is focused inside the substrate WF1 (step ST20). At this time, the laser light emitted from the first light source 21 of the first light source unit 20 is shaped into parallel light by the light source lens 22, and emitted from the first light source unit 20 as the first illumination light La. The first illumination light La emitted from the first light source unit 20 passes through the aperture number setting member 39 of the first illumination optical system 30 and is incident on the deflection scanning unit 31. The first illumination light La incident on the deflection scanning unit 31 is reflected in the X-direction deflector 31a and the Y-direction deflector 31b in this order, and is incident on the first relay lens 32. The first illumination light La that has passed through the first relay lens 32 is focused on the intermediate image plane Im and is incident on the second relay lens 33. The first illumination light La that has passed through the second relay lens 33 becomes parallel light and passes through the first dichroic mirror 34. The first illumination light La that has passed through the first dichroic mirror 34 passes through the second dichroic mirror 35. Figure 14 As shown, the first illumination light La, which passes through the second dichroic mirror 35, illuminates the substrate WF1 through the object optical system 36 and is focused at a focusing position set inside the substrate WF1.

[0125] When the first illumination light La is irradiated onto the substrate WF1, the deflection scanning unit 31 of the first illumination optical system 30 scans the interior of the substrate WF1 using the first illumination light La from the first light source unit 20. After the deflection scanning unit 31 scans the interior of the substrate WF1 in the observation area of ​​the substrate WF1 facing the object optical system 36, the optical device control unit 80 outputs a control signal to the stage 11 to move in the X or Y direction to the stage moving unit 12. By moving the stage 11 in the X or Y direction using the stage moving unit 12, the observation area of ​​the substrate WF1 facing the object optical system 36 can be displaced in the X or Y direction. Even if the observation area of ​​the substrate WF1 is displaced in the X or Y direction, the focusing position of the first illumination light La in the optical axis direction of the first illumination optical system 30 (object optical system 36) remains at the focusing position set inside the substrate WF1 through the autofocus control of the optical device control unit 80.

[0126] Next, the detection light Ld generated inside the substrate WF1 by the first illumination light La illuminating the substrate WF1 is received (step ST30). At this time, the detection light Ld generated inside the substrate WF1 (illumination region 25) by the multiphoton excitation caused by the first illumination light La is incident on the object optical system 36. The detection light Ld from the substrate WF1 incident on the object optical system 36 becomes parallel light through the object optical system 36 and passes through the second dichroic mirror 35. The detection light Ld that has passed through the second dichroic mirror 35 is reflected by the first dichroic mirror 34.

[0127] The detection light Ld reflected by the first dichroic mirror 34 passes through the third relay lens 42 and the suppression filter 43 of the first light-receiving optical system 41, and reaches the pupil conjugate surface of the object optical system 36 formed on the emission side of the third relay lens 42. The detection light Ld that has passed through the third relay lens 42 and the suppression filter 43 is incident on the detection surface 52 of the first detector 51, which is located on or near the pupil conjugate surface of the object optical system 36.

[0128] Next, the detection light Ld received by the first light-receiving optical system 41 is detected (step ST40). At this time, the first detector 51 performs photoelectric conversion on the detection light Ld incident on the detection surface 52 of the first detector 51 and outputs a first light-receiving signal. The first light-receiving signal output from the first detector 51 is acquired by the data acquisition unit 86.

[0129] Next, based on the detection signal (first light-receiving signal) of the detection light Ld detected by the first detector 51, image data of the interior of the substrate WF1 is generated (step ST50). At this time, the image processing unit 87 generates image data of the XY-direction cross-section (the direction perpendicular to the thickness direction of the substrate WF1) of the interior of the substrate WF1 based on the first light-receiving signal output from the first detector 51 and acquired by the data acquisition unit 86. The image data of the XY-direction cross-section of the interior of the substrate WF1 generated by the image processing unit 87 is sent from the interface unit 81 to the information processing device 90.

[0130] Then, based on the image data generated by the image processing unit 87, the presence of defects in the substrate WF1 is checked (step ST60). At this time, image data of the XY direction cross-section of the interior of the substrate WF1, sent from the interface unit 81 of the inspection optical device 10 (optical device control unit 80), is input to the interface unit 91 of the information processing device 90. The image data of the XY direction cross-section of the interior of the substrate WF1 input to the interface unit 91 is stored in the storage unit 95. Based on the image data of the XY direction cross-section of the interior of the substrate WF1 stored in the storage unit 95, the determination unit 96 determines whether there are defects inside the substrate WF1. The determination result of whether there are defects inside the substrate WF1 determined by the determination unit 96 is stored in the storage unit 95.

[0131] [Characteristic Structure of the First Implementation Form]

[0132] According to the first embodiment, the aperture number setting member 39 of the first illumination optical system 30 is set such that the number of illumination apertures of the first illumination light La is such that the distance between the substrate WF1 and the focusing position of the first illumination light La in the Z direction (optical axis direction of the first illumination optical system 30) is a first distance, and the number of illumination apertures of the first illumination light La is such that the distance between the substrate WF1 and the focusing position of the first illumination light La in the Z direction is a second distance longer than the first distance. Therefore, by reducing the number of illumination apertures of the first illumination light La as the effective NA decreases, the utilization efficiency of the first illumination light La increases, and thus the light (first illumination light La) irradiated onto the substrate WF1 can be effectively utilized.

[0133] Furthermore, the aperture number setting member 39 can also set the number of illumination apertures of the first illumination light La in such a way that the first illumination light La is focused according to the number of illumination apertures that satisfy the condition (1). Thus, by satisfying the condition (1), the peak intensity in the point image distribution function (PSF) can be increased, thereby enabling the number of illumination apertures of the first illumination light La to be set within a suitable range.

[0134] Furthermore, the number of openings setting member 39 can also set the number of illumination openings of the first illumination light La, which is focused into the interior of the substrate WF1 by the first illumination optical system 30, by changing the beam diameter of the first illumination light La. As a result, the structure of the number of openings setting member 39 can be simplified.

[0135] Alternatively, the first light-receiving optical system 41 of the first light-receiving section 40 can receive detection light Ld generated inside the substrate WF1 by multiphoton excitation, and the number of illumination openings of the first irradiation light La is less than the number of detection openings of the detection light Ld received by the first light-receiving optical system 41. Therefore, the first light-receiving optical system 41 (object optical system 36) can receive more detection light Ld generated inside the substrate WF1 by multiphoton excitation.

[0136] Alternatively, an image processing unit 87 may be included, which generates image data of the interior of the substrate WF1 based on the detection signal (first light-receiving signal) from the first detector 51. As described above, by setting the number of illumination openings of the first illumination light La within an appropriate range, image data of the interior of the substrate WF1 can be generated with high precision.

[0137] Alternatively, a determination unit 96 may be provided in the information processing device 90. This determination unit 96 determines whether defects exist inside the substrate WF1 based on image data of the interior of the substrate WF1 generated by the inspection optical device 10. As described above, by setting the number of illumination openings of the first irradiation light La within an appropriate range, the inspection accuracy in inspecting for defects inside the substrate WF1 can be improved. Furthermore, the determination unit 96 may also be provided in the optical device control unit 80 of the inspection optical device 10.

[0138] [Second Implementation Form]

[0139] Next, the defect inspection apparatus of the second embodiment will be described. In the defect inspection apparatus of the second embodiment, apart from the structure of the aperture number setting member in the inspection optical device and the structure of the first light-receiving part, the main parts are the same as those of the defect inspection apparatus 1 of the first embodiment. Therefore, for structures identical to those in the first embodiment, the same symbols as in the first embodiment are used, and detailed descriptions are omitted. For example... Figure 15 As shown, the defect inspection apparatus 101 in the second embodiment includes an inspection optical device 110 and an information processing device 90. The inspection optical device 110 and the information processing device 90 are configured to transmit and receive data to each other via a network cable NW. The inspection optical device 110 includes: a stage 11 on which a substrate WF2 is placed, a first light source unit 20, a first illumination optical system 130, a first light-receiving part 140, a surface detection unit 55, and an optical device control unit 80.

[0140] The stage 11 has the same structure as the stage 11 in the first embodiment, and detailed description is omitted. In the second embodiment, the stage 11 supports a substrate WF2, which is the object to be inspected. The substrate WF2 may, for example, have a layer made of SiC.

[0141] The first light source unit 20 has the same structure as the first light source unit 20 in the first embodiment, and detailed description is omitted. In the second embodiment, the first light source unit 20 emits a first irradiation light La toward the first irradiation optical system 130. The wavelength of the first irradiation light La is selected in the wavelength range that can excite the material constituting the substrate WF2 with a single photon to make it emit light.

[0142] The first illumination optical system 130 illuminates the substrate WF2 with the first illumination light La emitted from the first light source unit 20. The first illumination optical system 130, starting from the first light source unit 20 side, sequentially includes an aperture number setting member 139, a first dichroic mirror 134, a deflection scanning unit 31, a first relay lens 32, a second relay lens 33, a second dichroic mirror 35, and an object focusing optical system 36. The first dichroic mirror 134 is configured similarly to the first dichroic mirror 34 in the first embodiment. In the second embodiment, the first dichroic mirror 134 only needs to have the following characteristics: reflecting light generated inside the substrate WF2 by single-photon excitation, and allowing the first illumination light La from the first light source unit 20, which passes through the aperture number setting member 139, to pass through. Hereinafter, similar to the light generated inside the substrate WF1 by multi-photon excitation, the light generated inside the substrate WF2 by single-photon excitation is sometimes referred to as the detection light Ld.

[0143] The bias scanning unit 31, the first relay lens 32, the second relay lens 33, the second dichroic mirror 35, and the object optical system 36 have the same structure as those in the first embodiment, and detailed descriptions are omitted. In the second embodiment, the second relay lens 33 focuses the detection light Ld from the object optical system 36 (second dichroic mirror 35) onto the intermediate image plane Im. The first relay lens 32 converts the detection light Ld from the second relay lens 33 into parallel light and guides it to the bias scanning unit 31. The second dichroic mirror 35 only needs to have the following characteristics: it reflects the second illumination light Lb (and reflected light Le) from the surface detection unit 55, and allows the first illumination light La from the second relay lens 33 and the detection light Ld from the object optical system 36 to pass through.

[0144] The aperture number setting member 139 is configured, for example, using a zoom beam expander. The aperture number setting member 139 sets the angle of the first illumination light La, which is focused onto the interior of the substrate WF2 by the first illumination optical system 130, by changing the beam diameter of the first illumination light La emitted from the first light source unit 20. In other words, the aperture number setting member 139 can set the number of illumination apertures of the first illumination light La, which is focused onto the interior of the substrate WF2 by the first illumination optical system 130, by changing the beam diameter of the first illumination light La emitted from the first light source unit 20.

[0145] In the second embodiment, the number of illumination apertures of the first illumination light La can be equal to the number of detection apertures of the detection light Ld. That is, σ = 1. In other words, the beam diameter Da of the first illumination light La can be equal to the aperture diameter Dd of the object optical system 36. Therefore, the first light-receiving optical system 141 can focus more of the detection light Ld generated inside the substrate WF2 by single-photon excitation onto the image plane Imp. Furthermore, the number of illumination apertures of the first illumination light La can be approximately equal to the number of detection apertures of the detection light Ld. In other words, σ = 1 ± 0.5% or σ = 1 ± 1.0%.

[0146] The first light-receiving unit 140 includes a first light-receiving optical system 141 and a first detector 51. The first light-receiving optical system 141 receives detection light Ld generated inside the substrate WF2 (irradiation area 25) by single-photon excitation based on the first illumination light La, and forms an image 149 of the illumination area 25 inside the substrate WF2 on the image plane Imp. The first light-receiving optical system 141 includes an object-oriented optical system 36 of the first illumination optical system 130, a second dichroic mirror 35, a second relay lens 33, a first relay lens 32, a deflection scanning unit 31, and a first dichroic mirror 134. Furthermore, the first light-receiving optical system 141 includes, sequentially from the first dichroic mirror 134 side (substrate WF2 side), a suppression filter 143, a condenser lens 144, and a light-shielding plate 146 having a pinhole 145 (opening).

[0147] The suppressor filter 143 has the characteristic of allowing light (specifically, the detection light Ld) in a predetermined wavelength range from the light from the first dichroic mirror 134 to pass through. The suppressor filter 143, for example, blocks at least a portion of the first illumination light La reflected by the substrate WF2, external light, stray light, etc. Furthermore, the suppressor filter 143 is also referred to as a bandpass filter. The condenser lens 144 focuses the detection light Ld that has passed through the suppressor filter 143 onto the image plane Imp, thus imaging the image 149 of the illumination region 25 inside the substrate WF2. Furthermore, the substrate WF2 (object surface), the intermediate image plane Im, and the image plane Imp are conjugate surfaces. The condenser lens 144 is not limited to a single lens; multiple lenses can also be used. Additionally, a zoom optical system (not shown) capable of changing the size of the image 149 formed on the image plane Imp can be provided between the condenser lens 144 and the image plane Imp.

[0148] A light-shielding plate 146 is positioned near the image plane Imp. The light-shielding plate 146 allows only the light (detection light Ld) focused onto the image plane Imp by the condenser lens 144 to pass through the pinhole 145. Therefore, of the light from the substrate WF2, only the detection light Ld generated at the focusing position (irradiation area 25) of the first irradiation light La can pass through the pinhole 145. The first detector 51 has the same structure as the first detector 51 in the first embodiment, and detailed description is omitted. In the second embodiment, the detection surface 52 of the first detector 51 is positioned near the pinhole 145.

[0149] Alternatively, instead of the pinhole 145 and the first detector 51, a detector array including multiple detection pixels can be provided on the image plane Imp. Examples of detector arrays include avalanche photodiode arrays, complementary metal-oxide-semiconductor (CMOS) sensors, and charge-coupled device (CCD) sensors. The detector array can receive the image 149 of the illumination area 25 inside the substrate WF2 through multiple detection pixels and perform photoelectric conversion to output a first light-receiving signal. The image processing unit 87 can generate image data of the interior of the substrate WF2 based on the first light-receiving signal output from a specific single or multiple detection pixels in the detector array.

[0150] The surface detection unit 55 has the same structure as the surface detection unit 55 in the first embodiment, and detailed description is omitted. In the second embodiment, the wavelength of the second irradiation light Lb is selected in the wavelength range that the second dichroic mirror 35 can reflect (e.g., the wavelength range of green light). Alternatively, the wavelength of the second irradiation light Lb can be selected in the wavelength range that is reflectable on the surface of the substrate WF2.

[0151] The optical device control unit 80 has the same structure as the optical device control unit 80 in the first embodiment, and detailed description is omitted. In the second embodiment, the optical device control unit 80 controls the operation of the stage moving unit 12, the first light source unit 20 (first light source 21), the aperture number setting member 139, the bias scanning unit 31, the surface detection unit 55 (second light source 60, lens moving unit 69), etc., based on the control program stored in the storage unit 85.

[0152] [Inspection methods for substrates]

[0153] Next, the inspection method for the substrate WF2 using the defect inspection apparatus 101 of the second embodiment will be summarized. The inspection method for the substrate WF2 of the second embodiment is the same as the inspection method for the substrate WF1 of the first embodiment. Therefore, the method is the same as that of the first embodiment. Figure 13 The flowchart shown will be used for explanation. First, based on the setting information of the focusing position of the first irradiation light La and the substrate structure information stored in the storage unit 85, the defect inspection device 101 is set (step ST10). At this time, the calculation unit 88 calculates the control signal for controlling the aperture number setting member 139 of the first irradiation optical system 130, so as to set the number of illumination apertures of the first irradiation light La that satisfies the condition (1). The optical device control unit 80 outputs the control signal calculated by the calculation unit 88 to the aperture number setting member 139, thereby controlling the aperture number setting member 139. Under the control of the optical device control unit 80, the aperture number setting member 139 sets the number of illumination apertures of the first irradiation light La in a manner that satisfies the condition (1). In addition, the aperture number setting member 139 is set such that the longer the distance in the Z direction from the surface of the substrate WF2 to the focusing position of the first irradiation light La inside the substrate WF2, the smaller the number of illumination apertures of the first irradiation light La.

[0154] At this time, the calculation unit 88 calculates the offset L of the focusing position of the second irradiation light Lb relative to the focusing position of the first irradiation light La. When calculating the offset L, the calculation unit 88 can also adjust the focusing position of the first irradiation light La to correct the refractive index mismatch aberration generated in the substrate WF2. For example, the calculation unit 88 can also calculate the offset L based on a focusing position adjustment data table prepared in advance through optical simulation, according to the focusing position of the first irradiation light La set inside the substrate WF2 (depth from the surface of the substrate WF2).

[0155] The optical device control unit 80 outputs a control signal to the lens moving unit 69 of the surface detection unit 55, which can obtain the offset L calculated by the calculation unit 88. The lens moving unit 69 moves the concave lens 67b of the focal position adjusting lens 67 according to the control signal output from the optical device control unit 80. As a result, the focusing position of the second illumination light Lb irradiated from the object optical system 36 (the imaging position of the image of the slit opening 63a of the second illumination light Lb) moves by an offset L relative to the focusing position of the first illumination light La irradiated from the object optical system 36. In this state, by performing autofocus control by the optical device control unit 80, the focusing position of the first illumination light La irradiated from the object optical system 36 can be made to coincide with the focusing position of the first illumination light La set inside the substrate WF2.

[0156] Next, the first illumination light La is irradiated toward the substrate WF2, and the first illumination light La is focused inside the substrate WF2 (step ST20). At this time, the laser light emitted from the first light source 21 of the first light source unit 20 is shaped into parallel light by the light source lens 22, and emitted from the first light source unit 20 as the first illumination light La. The first illumination light La emitted from the first light source unit 20 passes through the aperture number setting member 139 of the first illumination optical system 130 and enters the first dichroic mirror 134. The first illumination light La that enters the first dichroic mirror 134 passes through the first dichroic mirror 134 and enters the deflection scanning unit 31. The first illumination light La that enters the deflection scanning unit 31 is reflected in this order in the X-direction deflection mirror 31a and the Y-direction deflection mirror 31b, and enters the first relay lens 32. The first illumination light La that has passed through the first relay lens 32 is focused on the intermediate image plane Im and enters the second relay lens 33. The first illumination light La, which passes through the second relay lens 33, becomes parallel light and passes through the second dichroic mirror 35. Similarly to the first embodiment, the first illumination light La, which passes through the second dichroic mirror 35, illuminates the substrate WF2 through the object optical system 36 and is focused at a focusing position set inside the substrate WF2.

[0157] When the first illumination light La is irradiated onto the substrate WF2, the deflection scanning unit 31 of the first illumination optical system 130 scans the interior of the substrate WF2 using the first illumination light La from the first light source unit 20. After the deflection scanning unit 31 scans the interior of the substrate WF2 in the observation area of ​​the substrate WF2 facing the object optical system 36, the optical device control unit 80 outputs a control signal to the stage 11 to move in the X or Y direction to the stage moving unit 12. By moving the stage 11 in the X or Y direction using the stage moving unit 12, the observation area of ​​the substrate WF2 facing the object optical system 36 can be displaced in the X or Y direction. Even if the observation area of ​​the substrate WF2 is displaced in the X or Y direction, the focusing position of the first illumination light La in the optical axis direction of the first illumination optical system 130 (object optical system 36) remains at the focusing position set inside the substrate WF2 through the autofocus control of the optical device control unit 80.

[0158] Next, the detection light Ld generated inside the substrate WF2 by the first illumination light La illuminating the substrate WF2 is received (step ST30). At this time, the detection light Ld generated inside the substrate WF2 (illumination region 25) by single-photon excitation based on the first illumination light La is incident on the object focusing optical system 36. The detection light Ld from the substrate WF2 incident on the object focusing optical system 36 becomes parallel light through the object focusing optical system 36 and passes through the second dichroic mirror 35. The detection light Ld that has passed through the second dichroic mirror 35 is incident on the second relay lens 33. The detection light Ld that has passed through the second relay lens 33 is focused on the intermediate image plane Im and incident on the first relay lens 32. The detection light Ld that has passed through the first relay lens 32 becomes parallel light and is incident on the deflection scanning unit 31. The detection light Ld incident on the deflection scanning unit 31 is reflected in the Y-direction deflection mirror 31b and the X-direction deflection mirror 31a in this order, and is reflected by the first dichroic mirror 134.

[0159] The detection light Ld reflected by the first dichroic mirror 134 passes through the suppression filter 143 of the first light-receiving optical system 141 and is incident on the condenser lens 144. The detection light Ld that has passed through the condenser lens 144 is focused onto the image plane Imp located near the light shield 146, so that the image 149 of the illumination area 25 inside the substrate WF2 is formed. Thus, in the light from the substrate WF2, only the detection light Ld generated at the focusing position (illumination area 25) of the first illumination light La can pass through the pinhole 145 of the light shield 146. The detection light Ld that has passed through the pinhole 145 of the light shield 146 is incident on the detection surface 52 of the first detector 51.

[0160] Next, the detection light Ld received by the first light-receiving optical system 141 is detected (step ST40). At this time, the first detector 51 performs photoelectric conversion on the detection light Ld that has passed through the pinhole 145 of the light-shielding plate 146 and outputs a first light-receiving signal. The first light-receiving signal output from the first detector 51 is acquired by the data acquisition unit 86.

[0161] Next, based on the detection signal (first light-receiving signal) of the detection light Ld detected by the first detector 51, image data of the interior of the substrate WF2 is generated (step ST50). At this time, the image processing unit 87 generates image data of the XY-direction cross-section of the interior of the substrate WF2 (the direction perpendicular to the thickness direction of the substrate WF1) based on the first light-receiving signal output from the first detector 51 and acquired by the data acquisition unit 86. The image data of the XY-direction cross-section of the interior of the substrate WF2 generated by the image processing unit 87 is sent from the interface unit 81 to the information processing device 90.

[0162] Then, based on the image data generated by the image processing unit 87, the presence of defects in the substrate WF2 is checked (step ST60). At this time, image data of the XY direction cross-section of the interior of the substrate WF2, sent from the interface unit 81 of the inspection optical device 110 (optical device control unit 80), is input to the interface unit 91 of the information processing device 90. The image data of the XY direction cross-section of the interior of the substrate WF2 input to the interface unit 91 is stored in the storage unit 95. Based on the image data of the XY direction cross-section of the interior of the substrate WF2 stored in the storage unit 95, the determination unit 96 determines whether there are defects inside the substrate WF2. The determination result of whether there are defects inside the substrate WF2 determined by the determination unit 96 is stored in the storage unit 95.

[0163] [Characteristic Structure of the Second Implementation Form]

[0164] According to the second embodiment, the same effect as the first embodiment can be obtained. Furthermore, in the second embodiment, the first light-receiving optical system 141 of the first light-receiving section 140 receives the detection light Ld generated inside the substrate WF2 by single-photon excitation, and the number of illumination openings of the first illumination light La is equal to the number of detection openings of the detection light Ld received by the first light-receiving optical system 141. Therefore, the first light-receiving optical system 141 can focus more of the detection light Ld generated inside the substrate WF2 by single-photon excitation onto the image plane Imp.

[0165] In each of the embodiments, the first light source unit 20 is configured to be detachable and replaceable from the inspection optical device, but is not limited thereto, and may also be set separately from the inspection optical device.

[0166] In each of the embodiments described, the substrate structure information or the setting information of the focusing position of the first illumination light La is input to the interface of the optical device control unit, but is not limited thereto. For example, a user-operable input unit may be connected to the optical device control unit, and the substrate structure information or the setting information of the focusing position of the first illumination light La may be input to the input unit. The input unit may be configured using at least one of a mouse, keyboard, touchpad, trackball, etc.

[0167] At least a portion of the constituent elements of each embodiment may be suitably combined with at least another portion of the constituent elements of each embodiment. A portion of the constituent elements of each embodiment may also be omitted.

[0168] This invention is not limited to the embodiments described herein. Appropriate modifications may be made without departing from the spirit or concept of the invention as read in its entirety from the claims and the specification. Inspection optical devices, defect inspection devices, irradiation optical systems, and inspection methods that accompany such modifications are also included within the scope of this invention.

[0169] Explanation of icon numbers

[0170] 1: Defect inspection device (first embodiment)

[0171] 10: Inspection optical devices

[0172] 11: Platform

[0173] 12: Platform Moving Unit

[0174] 20: First Light Source Unit

[0175] 30: First Illumination Optical System

[0176] 39: Component for setting the number of openings

[0177] 40: First light-receiving part

[0178] 41: First light-receiving optical system

[0179] 51: First Detector

[0180] 80: Optical Device Control Unit

[0181] 87: Image Processing Department

[0182] 90: Information processing device

[0183] 96: Judgment Department

[0184] 101: Defect Inspection Device (Second Embodiment)

[0185] 110: Inspection optical device

[0186] 130: First Illumination Optical System

[0187] 139: Component for setting the number of openings

[0188] 140: First Light-Receiving Section

[0189] 141: First light-receiving optical system

[0190] WF1: Substrate (First Embodiment)

[0191] WF2: Substrate (Second Embodiment)

Claims

1. An optical apparatus for inspecting a substrate, the optical apparatus comprising: An illumination optical system illuminates the substrate with illumination light and focuses the illumination light into the interior of the substrate. A light-receiving optical system that receives light generated inside the substrate by the illumination light that is irradiated onto the substrate; as well as The distance changing device changes the distance along the optical axis of the irradiation optical system between the substrate and the focusing position of the irradiation light. The illumination optical system includes an aperture number setting component, which is set such that the number of apertures of the illumination light when the distance is a first distance is greater than the number of apertures of the illumination light when the distance is a second distance longer than the first distance.

2. The optical device for inspection according to claim 1, wherein, The number of openings setting component sets the number of openings in such a way that the irradiated light is focused by the number of openings that satisfy the following condition. [Number 1] Wherein, NAi: the number of openings nim: The refractive index of the medium between the substrate and the irradiation optical system z: Position of the optical axis of the focal point of the illumination optical system, with the surface of the substrate facing the illumination optical system as a reference position. λ: The wavelength of the irradiated light f(t): a function of t, defined by the following formula when the refractive index of the substrate is set as nsa, and t = nsa / nim. f(t)=1.068-0.006502t+3.837exp(-3.175t).

3. An optical apparatus for inspecting a substrate, the optical apparatus comprising: An illumination optical system illuminates the substrate with illumination light and focuses the illumination light into the interior of the substrate. as well as A light-receiving optical system that receives light generated inside the substrate by the illumination light that is incident on the substrate. The illumination optical system includes an aperture number setting component, which sets the aperture number in a manner that concentrates the illumination light according to the following condition: [Number 2] Wherein, NAi: the number of openings nim: The refractive index of the medium between the substrate and the irradiation optical system z: Position of the optical axis of the focal point of the illumination optical system, with the surface of the substrate facing the illumination optical system as a reference position. λ: The wavelength of the irradiated light f(t): a function of t, defined by the following formula when the refractive index of the substrate is set as nsa, and t = nsa / nim. f(t)=1.068-0.006502t+3.837exp(-3.175t).

4. The optical device for inspection according to any one of claims 1 to 3, wherein, The illumination light is a laser beam. The aperture number setting component sets the aperture number by changing the beam diameter of the irradiated light.

5. The optical device for inspection according to any one of claims 1 to 4, wherein, The light-receiving optical system receives light generated inside the substrate by multiphoton excitation through the illumination light that is irradiated onto the substrate. The number of openings in the irradiating light is less than the number of openings in the light received by the light-receiving optical system.

6. The optical device for inspection according to any one of claims 1 to 4, wherein, The light-receiving optical system receives light generated inside the substrate by single-photon excitation through the illumination light that is irradiated onto the substrate. The number of openings in the irradiating light is equal to the number of openings in the light received by the light-receiving optical system.

7. The optical device for inspection according to any one of claims 1 to 6, comprising: The detection unit detects the light received by the light-receiving optical system and outputs a detection signal; as well as The processing unit generates information about the interior of the substrate based on the detection signal from the detection unit.

8. A defect inspection apparatus, comprising the inspection optical device according to claim 7, Defects in the substrate are inspected based on information about the interior of the substrate generated by the inspection optical device.

9. An illumination optical system for illuminating a substrate with illumination light and focusing the illumination light into the interior of the substrate. The illumination optical system includes an aperture number setting component, which sets the aperture number in a manner that concentrates the illumination light according to the following condition: [Number 3] in, NAi: The number of openings nim: The refractive index of the medium between the substrate and the irradiation optical system z: Position of the optical axis of the focal point of the illumination optical system, with the surface of the substrate facing the illumination optical system as a reference position. λ: The wavelength of the irradiated light f(t): a function of t, defined by the following formula when the refractive index of the substrate is set as nsa, and t = nsa / nim. f(t)=1.068-0.006502t+3.837exp(-3.175t).

10. The illumination optical system according to claim 9, wherein, The aperture number setting component includes a variable aperture disposed at the pupil position or pupil conjugate position in the illumination optical system.

11. An inspection method for a substrate, comprising: Irradiate the substrate with illumination light and focus the illumination light into the interior of the substrate; Receive light generated inside the substrate by the illumination light that is irradiated onto the substrate; as well as The distance between the substrate and the focusing position of the irradiation light in the optical axis direction of the irradiation optical system is changed. When focusing the illumination light, the number of openings of the illumination light when the distance is a first distance is greater than the number of openings of the illumination light when the distance is a second distance longer than the first distance.

12. An inspection method for a substrate, comprising: Irradiate the substrate with illumination light and focus the illumination light into the interior of the substrate; as well as Receives light generated inside the substrate by the illumination light that is irradiated onto the substrate. When focusing the irradiation light, the number of openings is set in a manner that satisfies the following condition: [Number 4] Wherein, NAi: the number of openings nim: The refractive index of the medium between the substrate and the irradiation optical system z: Position of the optical axis of the focal point of the illumination optical system, with the surface of the substrate facing the illumination optical system as a reference position. λ: The wavelength of the irradiated light f(t): a function of t, defined by the following formula when the refractive index of the substrate is set as nsa, and t = nsa / nim. f(t)=1.068-0.006502t+3.837exp(-3.175t).

Images