Wafer Inspection Equipment

Abstract

To provide a wafer inspection device capable of detecting various types of defects with one light beam. [Solution] The wafer inspection device comprises a support for supporting the wafer (14), an optical system (26) for irradiating the wafer (14) with linearly polarized light rays (16a) that are incident perpendicularly to the surface of the wafer (14), a first light receiving element (27) that receives components other than linearly polarized light from the light rays (16b) reflected from the surface of the wafer (14) and outputs an electrical signal according to the intensity, a second light receiving element (28) that receives the linearly polarized component from the light rays (16b) reflected from the surface of the wafer (14) and outputs an electrical signal according to the intensity, and a control unit that detects defects in the wafer (14) based on the electrical signal from the first light receiving element (27) and the electrical signal from the second light receiving element (28).

Description

[Technical Field]

[0001] The present invention relates to a wafer inspection apparatus that detects defects on a wafer based on irradiation with a light beam. [Background technology]

[0002] Patent Document 1 discloses a wafer inspection device that irradiates a light beam onto the surface of a wafer and detects defects on the wafer based on the reflected light. The wafer inspection device detects particles (tiny foreign matter or defect particles), COPs (particulate defects), residues (residues of chemical substances, fine particles, or impurities), and scratches (fine scratches) that are approximately 0.1 μm in size, as well as LLPDs that are up to approximately 16 μm in size. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-38254 Summary of the Invention [Problem to be solved by the invention]

[0004] Wafer inspection equipment combines dark-field and bright-field inspection. In dark-field inspection, light rays are projected onto the wafer surface at a large angle of incidence to generate diffusely reflected light. The diffusely reflected light is collected normal to the wafer surface. In bright-field inspection, light rays are projected onto the wafer surface from a normal angle to form an image. The reflected light is collected normal to the wafer surface. The optical system becomes more complex for wafer surfaces.

[0005] An object of the present invention is to provide a wafer inspection device that can detect various types of defects using a single light beam. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a wafer inspection device comprising: a support for supporting a wafer; an optical system for irradiating the wafer with linearly polarized light rays that are incident perpendicularly to the surface of the wafer; a first light receiving element for receiving components other than the linearly polarized light from the light rays reflected from the surface of the wafer and outputting an electrical signal according to the intensity; a second light receiving element for receiving the linearly polarized component from the light rays reflected from the surface of the wafer and outputting an electrical signal according to the intensity; and a control unit for detecting defects on the wafer based on the electrical signal from the first light receiving element and the electrical signal from the second light receiving element. [Effects of the Invention]

[0007] As described above, according to the disclosed embodiment, a wafer inspection device capable of detecting various types of defects with one light beam is provided. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating the configuration of a wafer inspection device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating the configuration of an optical path unit. [Figure 3] FIG. 10 is a schematic diagram illustrating the configuration of an optical path unit used in a wafer inspection device according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a schematic diagram illustrating the configuration of an optical path unit used in a wafer inspection device according to a third embodiment of the present invention. [Figure 5] FIG. 10 is a schematic diagram illustrating the configuration of an optical path unit used in a wafer inspection device according to a fourth embodiment of the present invention. [Figure 6] FIG. 10 is a schematic diagram illustrating the configuration of an optical path unit used in a wafer inspection device according to a fifth embodiment of the present invention. [Figure 7] FIG. 13 is a schematic diagram illustrating the configuration of an optical path unit used in a wafer inspection device according to a sixth embodiment of the present invention. [Figure 8]FIG. 13 is a schematic diagram illustrating the configuration of a control unit used in a wafer inspection device according to a seventh embodiment of the present invention. [Figure 9] FIG. 2 is a plan view schematically showing the structure of a wafer. [Figure 10] FIG. 2 is an enlarged partial cross-sectional view schematically showing the structure of a wafer. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] FIG. 1 shows a schematic configuration of a wafer inspection apparatus 11 according to a first embodiment of the present invention. The wafer inspection apparatus 11 includes a chamber 13 defining a clean room 12, a support 15 housed in the clean room 12 and supporting a wafer 14, an inspection head 17 housed in the clean room 12 and irradiating a light beam 16a perpendicular to the surface of the wafer 14 and receiving a light beam 16b reflected perpendicularly from the wafer 14, and a light source group 18 supplying light beams to the inspection head 17. The clean room 12 may be filled with air or an inert gas. Atmospheric pressure or a vacuum may be established within the clean room 12. The wafer is formed, for example, from silicon (Si). The wafer is formed into a disk having a diameter of, for example, 300 mm.

[0011] The wafer inspection device 11 includes a displacement mechanism 21 that displaces the light beam 16a relative to the wafer 15. Here, the inspection head 17 is fixed immovably within the clean room 12. The displacement mechanism 21 is connected to the support 15. The displacement mechanism 21 drives the support 15 according to an xy coordinate system set in a horizontal plane. The wafer 14 on the support 15 is displaced horizontally in nanometer units.

[0012] The inspection head 17 includes a frame 23 that connects and supports multiple optical path units 22. Each optical path unit 22 individually guides the separated light beams 16a, 16b. The inspection head 17 functions as an optical system that guides the multiple light beams 16a, 16b in parallel. The inspection head 17 forms light spots in a predetermined positional relationship on the surface of the wafer 14. The light spots may be arranged, for example, at equal intervals on a straight line. The light spots may also be arranged in a matrix (array).

[0013] As shown in FIG. 2, each optical path unit 22 includes an individual optical system 26 that guides a light beam 16a from one light source 18a in the light source group 18 to the surface of the wafer 14; a first light-receiving element (photodiode) 27 that separates and receives linearly polarized light from the light beam 16b reflected from the surface of the wafer 14; and a second light-receiving element (photodiode) 28 that separates and receives linearly polarized light from the light beam 16b reflected from the surface of the wafer 14. The first light-receiving element 27 receives light beams with polarization rotated from the linear polarization of the light beam 16a irradiating the wafer 14. The first light-receiving element 27 detects the intensity of the light beams with a polarization plane rotated due to defects in the wafer 14. The first light-receiving element 27 outputs an electrical signal corresponding to the detected intensity of the light beam. The second light-receiving element 28 receives light beams with linear polarization that are maintained from the light beam 16a irradiating the wafer 14. The second light receiving element 28 detects the intensity of the polarized light that remains regardless of defects on the wafer 14. The second light receiving element 28 outputs an electrical signal corresponding to the intensity of the detected light beam.

[0014] The individual optical system 26 includes a first half-wave plate 31 that adjusts the angle of the linearly polarized light, a first polarizing beam splitter 32 that transmits p-polarized light and reflects s-polarized light, a Faraday rotator 33 that rotates the polarization plane by 45°, a second half-wave plate 34 that adjusts the angle of the linearly polarized light, a second polarizing beam splitter 35 that transmits p-polarized light and reflects s-polarized light, and an objective lens 36 that adjusts the focus. Linearly polarized light is supplied to the first half-wave plate 31 from one light source 18a. The light source 18a generates near-infrared light with a wavelength of, for example, 980 nm. The light source 18a may be, for example, a semiconductor laser element, a light-emitting diode, or another semiconductor light-emitting element. The light is introduced from the light source 18a into the optical path unit 22 via a PANDA fiber 37. The PANDA fiber 37 maintains the linear polarization of the light. The light beam 16a passes through a first half-wave plate 31, a first polarizing beam splitter 32, a Faraday rotator 33, a second half-wave plate 34, a second polarizing beam splitter 35, and an objective lens 36, and is incident on the wafer 14 perpendicular to the surface of the wafer 14 (at an incident angle of 0°). The linear polarization of the light beam 16a is maintained. In this example, the light source 18a is installed outside the chamber body 13. The optical path may be split by a coupler 38. The light source 18a may be isolated from the vacuum in the clean room 12. However, the light source 18a may also be located inside the clean room 12.

[0015] The objective lens 36 receives the light ray 16b that is reflected perpendicularly from the surface of the wafer 14. The second polarizing beam splitter 35 separates the linearly polarized light from the reflected light. The light ray that has a polarization rotated from the linear polarization of the light ray 16a that is incident on the wafer 14 is reflected by the second polarizing beam splitter 35. The light ray reflected by the second polarizing beam splitter 35 reaches the first light receiving element 27. The light ray that has the linear polarization that is maintained from the light ray 16a that is incident on the wafer 14 is transmitted through the second polarizing beam splitter 35. The first polarizing beam splitter 32 separates the linearly polarized light from the reflected light. The light ray that has the linear polarization that is maintained from the light ray 16a that is incident on the wafer 14 is reflected by the first polarizing beam splitter 32. The light ray reflected by the first polarizing beam splitter 32 reaches the second light receiving element 28. The light beam 16 a irradiating the wafer 14 has a polarization rotated from the linear polarization of the light beam 16 a and passes through the first polarizing beam splitter 32 .

[0016] A control unit 39 is connected to the displacement mechanism 21 and the inspection head 17, controlling their operation. The control unit 39 supplies a control signal to the displacement mechanism 21. The control signal defines the position of the support 15 according to the x-, y-, and z-coordinate axes in three-dimensional space. The wafer 14 is positioned relative to the light beam 16a. The control unit 39 receives electrical signals from the first light receiving element 27 and the second light receiving element 28 for each position. The control unit 39 scans the light beam 16a evenly over the surface of the wafer 14 along a determined path. The control unit 39 calculates the intensity distribution of the light beam 16b on the surface of the wafer 14, consisting of linearly polarized and non-linearly polarized light components.

[0017] Next, the operation of the wafer inspection apparatus 11 will be described. The wafer 14 is placed on the support 15. The control unit 39 supplies a control signal to the light source 18a. In response to the supplied control signal, the light source 18a emits near-infrared light. Linear polarization is established in the light beam. The linearly polarized light beam passes through the PANDA fiber 37, the first half-wave plate 31, the first polarizing beam splitter 32, the Faraday rotator 33, the second half-wave plate 34, the second polarizing beam splitter 35, and the objective lens 36. The light beam 16a is irradiated onto the surface of the wafer 14 while maintaining its linear polarization. The linearly polarized light beam 16a is incident perpendicularly on the surface of the wafer 14.

[0018] Light ray 16b reflected perpendicularly from the surface of wafer 14 passes through objective lens 36. Light ray 16b enters second polarizing beam splitter 35. Linearly polarized light is separated from light ray 16b. Light rays with the maintained linear polarization from light ray 16a pass through second polarizing beam splitter 35. Light rays with polarization rotated from the linear polarization of light ray 16a irradiating wafer 14 are reflected at the boundary surface of second polarizing beam splitter 35. Light rays other than the separated linearly polarized light are received by first light receiving element 27. First light receiving element 27 outputs an electrical signal according to the intensity of the light ray. The electrical signal is passed to control unit 39.

[0019] The light beam transmitted through the second polarizing beam splitter 35 passes through the second half-wave plate 34 and the Faraday rotator 33. The light beam 16b is reflected at the boundary surface of the first polarizing beam splitter 32. The linearly polarized light beam is separated from the light beam 16b. The separated linearly polarized light beam is received by the second light receiving element 28. The second light receiving element 28 outputs an electrical signal according to the intensity of the light beam. The electrical signal is passed to the control unit 39.

[0020] The control unit 39 causes the wafer 14 to be displaced along a predetermined path in a horizontal plane. A control signal is sent from the control unit 39 to the displacement mechanism 21 to displace the wafer 14. Since multiple light beams 16a are emitted in parallel, the amount of displacement of the wafer 14 decreases. The light beams 16a scan the entire area of ​​the wafer 14. The control unit 39 generates an intensity distribution of the light beams over the entire area of ​​the wafer 14. The control unit 39 may generate an image that visually displays the intensity distribution.

[0021] If a defect smaller than the illuminated light spot exists on the surface of the wafer 14, the reflected light beam 16b will be depolarized. The second light receiving element 27 receives the change in polarization. Depending on the change in polarization, defects such as particles (tiny foreign matter or defect particles), COP (particulate defects), residues (residues of chemical substances, fine particles, or impurities) approximately 0.1 μm in size, and scratches (fine scratches), are detected. If a defect larger than the illuminated light spot exists on the surface of the wafer 14, the second light receiving element 28 receives the change in reflectance. Depending on the change in reflectance, LLPDs up to approximately 16 μm in size are detected. LLPDs include particles, COP, residue, and scratches. Because linearly polarized and non-linearly polarized components can be separated from a single common light beam, various types of defects can be detected with a single light beam. Because the light beam is displaced relative to the wafer 14, defects are detected across the entire wafer 14.

[0022] In this embodiment, the individual optical system 26 includes an objective lens 36 having an optical axis perpendicular to the surface of the wafer 14. Light rays are emitted from the objective lens 36 perpendicular to the surface of the wafer 14. Light rays reflected from the wafer 14 enter the objective lens 36 perpendicular to the surface of the wafer 14. The optical path can be limited to only the objective lens 36. The structure of the optical system is simplified relative to the surface of the wafer 14. The optical system is reduced.

[0023] In the inspection head 17 according to this embodiment, a single support 15 is provided with a frame 23 that holds a plurality of individual optical systems 26 that guide a plurality of light beams 16a in parallel, and a first light receiving element 27 and a second light receiving element 28 that are combined with each individual optical system 26. Defects are detected at a plurality of locations on the wafer 14 simultaneously in accordance with the parallel light beams. The operating time required for defect detection is shortened. Because the optical systems are reduced in size, the optical systems are arranged at a high density relative to the surface of the wafer 14.

[0024] FIG. 3 shows a schematic configuration of an optical path unit 41 used in a wafer inspection apparatus according to a second embodiment of the present invention. The optical path unit 22 in the wafer inspection apparatus 11 can be replaced with the optical path unit 41. The individual optical systems 42 of the optical path unit 41 include a first half-wave plate 31, a first polarizing beam splitter 32, a Faraday rotator 33, a second half-wave plate 34, and a second polarizing beam splitter 35; a scan mirror 43 that receives the light beam transmitted through the second polarizing beam splitter 35 and oscillates around a horizontal axis; and fθ lenses 44a and 44b that receive the light beam from the scan mirror 43 and direct it vertically to the objective lens 36. A galvanometer mirror, for example, is used as the scan mirror 43. The galvanometer mirror scans the light beam 16a along the x-coordinate axis. The displacement of the support 15 is reduced in response to the scanning of the light beam 16a.

[0025] FIG. 4 shows a schematic configuration of an optical path unit 51 used in a wafer inspection apparatus according to a third embodiment of the present invention. The optical path unit 22 in the wafer inspection apparatus 11 can be replaced with the optical path unit 51. In addition to the configuration of the individual optical systems 42, the optical path unit 51 includes a focusing mechanism (autofocus optical system) 53 that detects the focus of the objective lens 36 and drives the objective lens 36 to the direction of its optical axis based on the detected focus. The focusing mechanism 53 detects the focus of the objective lens 36 using, for example, an astigmatism method. Light reflected from the wafer 14 is guided from a cylindrical lens 54 to a four-segment photodetector 55. When the objective lens 36 focuses on the surface of the wafer 14, a circular spot is formed on the four-segment photodetector 55. The four photodetectors are uniformly illuminated with light. If the objective lens 36 is closer or farther from the focused position, an elliptical spot is formed on the four-segment photodetector 55. A driving element 56 drives the objective lens 36 in response to the output of the four-segment photodetector 55. For example, a piezoelectric actuator is used as the driving element 56. A driving voltage is applied to the piezoelectric actuator in response to the output of the four-segment photodetector 55. An optical path 58 established from the light source 57 to the objective lens 36 is provided with a polarizing beam splitter 59 that separates the detection light from the optical path 58, a quarter-wave plate 61 that converts the light beam between linearly polarized and circularly polarized light, and a beam splitter 62 that separates the light beam from on the optical path 36a of the objective lens 36. Here, the objective lens 36 is formed with a numerical aperture NA that provides a focal depth smaller than the height difference formed on the surface of the wafer 14.

[0026] The focusing mechanism 53 focuses the objective lens 36 on the surface of the wafer 14 in response to the movement of the objective lens 36. A large numerical aperture is required for the objective lens 36 to collect diffusely reflected light. A large numerical aperture reduces the depth of focus. Even if defocus occurs due to differences in elevation on the surface of the wafer 14, the focusing mechanism 53 eliminates the defocus in response to the movement of the objective lens 36. A good focusing state is established while effectively collecting diffusely reflected light. Any defects on the wafer 14 are easily detected.

[0027] FIG. 5 shows a schematic configuration of an optical path unit 65 used in a wafer inspection apparatus according to a fourth embodiment of the present invention. The optical path unit 22 in the wafer inspection apparatus 11 can be replaced with the optical path unit 65. In addition to the components of the optical path unit 51, the optical path unit 65 includes a third light receiving element 67 that receives the fluorescence separated from components other than linearly polarized light, and a fourth light receiving element 68 that receives the fluorescence separated from components of linearly polarized light. The third light receiving element 67 is combined with a dichroic mirror 69, which is disposed between the second polarizing beam splitter 35 and the first light receiving element 27. The dichroic mirror 69 separates the excitation light and the fluorescence (long wavelength) from the light beam that is reflected by the second polarizing beam splitter 35 and contains components other than linearly polarized light. The fourth light receiving element 68 is combined with a dichroic mirror 71, which is disposed between the first polarizing beam splitter 32 and the second light receiving element 28. The dichroic mirror 71 splits the excitation light and the fluorescence (long wavelength) from the light beam containing the linearly polarized component reflected by the first polarizing beam splitter 32. The third light receiving element 67 and the fourth light receiving element 68 output electrical signals according to the intensity of the fluorescence. To detect the fluorescence, the third light receiving element 67 and the fourth light receiving element 68 may be a photodetector (PD), a photomultiplier tube (PMT), or an avalanche photodiode (APD).

[0028] The silicon wafer 14 emits fluorescence in response to dislocation defects. Dislocation defects occur due to misalignment or distortion of the atomic arrangement. The third light receiving element 67 and the fourth light receiving element 68 receive the fluorescence. Dislocation defects are detected in response to the received fluorescence. Dislocation defects are separated from defects such as particles (tiny foreign matter or defect particles), COPs (particulate defects), residues (residues of chemical substances, fine particles, and impurities), and scratches (fine scratches).

[0029] FIG. 6 shows a schematic configuration of an optical path unit 73 used in a wafer inspection apparatus according to a fifth embodiment of the present invention. The optical path unit 22 in the wafer inspection apparatus 11 can be replaced with the optical path unit 73. In addition to the components of the optical path unit 51, the optical path unit 73 further includes a third light receiving element 74 that receives fluorescence separated from components other than linearly polarized light for each specific wavelength, and a fourth light receiving element 75 that receives fluorescence separated from components of linearly polarized light for each specific wavelength. The third light receiving element 74 is combined with a dichroic mirror 76 disposed between the second polarizing beam splitter 35 and the first light receiving element 27, and a diffraction grating 77 that separates the fluorescence split by the dichroic mirror 76. The dichroic mirror 76 splits the light beam containing components other than linearly polarized light reflected by the second polarizing beam splitter 35 into excitation light and fluorescence (long wavelength). The third light receiving element 74 may be, for example, a line sensor. The line sensor receives the fluorescence for each separated wavelength. The third light receiving element 74 outputs an electrical signal corresponding to the intensity of the fluorescent light for each wavelength.

[0030] The fourth light receiving element 75 is combined with a dichroic mirror 78, which is placed between the first polarizing beam splitter 32 and the second light receiving element 28, and a diffraction grating 79 that separates the fluorescence split by the dichroic mirror 78. The dichroic mirror 78 separates the light beam containing linearly polarized components reflected by the first polarizing beam splitter 32 into excitation light and fluorescence (long wavelength). For example, a line sensor is used for the fourth light receiving element 75. The line sensor receives the fluorescence for each of the separated wavelengths. The fourth light receiving element 75 outputs an electrical signal corresponding to the intensity of the fluorescence for each wavelength.

[0031] The silicon wafer 14 emits fluorescence in response to dislocation defects. Dislocation defects occur due to misalignment or distortion of the atomic arrangement. The third light receiving element 74 and the fourth light receiving element 75 receive the fluorescence. Dislocation defects are detected based on the received fluorescence. Dislocation defects are separated from defects such as particles (tiny foreign matter or defect particles), COP (particulate defects), residue (residue of chemical substances, fine particles, or impurities), and scratches (fine scratches). When the fluorescence is received, it is dispersed by diffraction gratings 77 and 79. The intensity of the fluorescence is detected for each wavelength. Dislocation defects are classified according to wavelength: D1, D2, D3, and D4.

[0032] FIG. 7 shows a schematic configuration of an optical path unit 81 used in a wafer inspection apparatus according to a sixth embodiment of the present invention. The optical path unit 22 in the wafer inspection apparatus 11 can be replaced with the optical path unit 81. In addition to the components of the optical path unit 51, the optical path unit 81 includes a third light receiving element 82 that receives fluorescence separated from components other than linearly polarized light for each specific wavelength, and a fourth light receiving element 83 that receives fluorescence separated from components of linearly polarized light for each specific wavelength. The third light receiving element 82 is combined with a dichroic mirror 84, which is disposed between the second polarizing beam splitter 35 and the first light receiving element 27, and a diffraction grating 85 that separates the fluorescence split by the dichroic mirror 84. The dichroic mirror 84 splits the light beam, including components other than linearly polarized light, reflected by the second polarizing beam splitter 35 into excitation light and fluorescence (long wavelength). A MEMS (micro-mechanical system) 86 that drives the diffraction grating 85 is connected to the diffraction grating 85. The third light receiving element 82 receives the fluorescence for each of the separated wavelengths due to the function of the MEMS 86. The third light receiving element 82 outputs an electrical signal according to the intensity of the fluorescence for each wavelength.

[0033] The fourth light receiving element 83 is combined with a dichroic mirror 87, which is placed between the first polarizing beam splitter 32 and the second light receiving element 28, and a diffraction grating 88 that separates the fluorescence split by the dichroic mirror 87. The dichroic mirror 87 separates the excitation light and the fluorescence (long wavelength) from the light beam containing the linearly polarized component reflected by the first polarizing beam splitter 32. A MEMS (micro-mechanical system) 89 that drives the diffraction grating 88 is connected to the diffraction grating 88. The MEMS 89 functions to cause the fourth light receiving element 83 to receive the fluorescence for each of the separated wavelengths. The fourth light receiving element 83 outputs an electrical signal corresponding to the intensity of the fluorescence for each wavelength.

[0034] The silicon wafer 14 emits fluorescence in response to dislocation defects. Dislocation defects occur due to misalignment or distortion of the atomic arrangement. The third light receiving element 82 and the fourth light receiving element 83 receive the fluorescence. Dislocation defects are detected based on the received fluorescence. Dislocation defects are separated from defects such as particles (tiny foreign matter or defect particles), COP (particulate defects), residue (residue of chemical substances, fine particles, or impurities), and scratches (fine scratches). When the fluorescence is received, it is dispersed by diffraction gratings 85 and 88. The intensity of the fluorescence is detected for each wavelength. Dislocation defects are classified according to wavelength: D1, D2, D3, and D4.

[0035] FIG. 8 schematically illustrates a control unit 91 used in a wafer inspection apparatus according to a seventh embodiment of the present invention. The control unit 39 in the wafer inspection apparatus 11 can be replaced with the control unit 91. The control unit 91 includes a microprocessor (MPU) 93 that compares actual measurement data of the wafer 92 with registered data for the wafer 92. To generate the actual measurement data, the MPU 93 receives electrical signals from the first light receiving element 27 and the second light receiving element 28. The light beam 16a scans the surface of the wafer 92 evenly along a path determined by the displacement mechanism 21. The control unit 91 determines the intensity distribution of the light beam 16b across the entire surface of the wafer 92. The intensity of linearly polarized light and the intensity of non-linearly polarized light are calculated for each coordinate point in the xy plane. As shown in FIG. 9, a circuit pattern 94, for example, is formed on the surface of the wafer 92. Identical electronic circuits are fabricated on each die 95.

[0036] The registered data is stored in, for example, a storage device 96. The registered data is formed in advance from output signals of an assumed good wafer 92 from the first light receiving element 27 and the second light receiving element 28. The intensity of linearly polarized light and the intensity of non-linearly polarized light are calculated for each coordinate point in the xy plane. For example, CAD data of the wafer 92 is used in the calculation. If the actual measurement data deviates from the registered data, the control unit 91 detects a defect in the circuit pattern 94.

[0037] Alternatively, as shown in FIG. 10 , the control units 39 and 91 may generate a distribution of non-linearly polarized light across the entire surface of the wafer 97 based on the electrical signal of the first light-receiving element 27. For example, if an oxide film 102 is uniformly formed on the surface of a silicon substrate 101 by thermal oxidation, a metal film or other thin film 103 is uniformly formed, a photoresist 104 is uniformly applied, or an STI (shallow trench isolation) 106 embedded in an active region 105 is planarized, non-linearly polarized light will be detected uniformly across the entire surface of the wafer 97. If a defect exists, the reflected light beam 16b will be depolarized. The first light-receiving element 27 receives the change in polarization. Depending on the change in polarization, defects in the oxide film 102, the thin film 103, the photoresist 104, and the STI 106 are detected. Here, the control units 39, 91 may create a distribution of linearly polarized light over the entire surface of the wafer 97 based on the electrical signal of the second light receiving element 28 instead of the electrical signal of the first light receiving element 27. The control units 39, 91 may create a distribution of linearly polarized light and non-linearly polarized light over the entire surface of the wafer 97 based on the electrical signals of the first light receiving element 27 and the second light receiving element 28. Because the linearly polarized light component and the non-linearly polarized light component can be separated from a single common light beam, various types of defects can be detected using a single light beam. [Explanation of symbols]

[0038] 11 Wafer inspection equipment 14 wafers 15 Support 16a Ray of light 16b Ray of light 21 Displacement mechanism 23 frames 26 Optical system (individual optical system) 27 First light receiving element 28 Second light receiving element 36 Objective Lens 39 Control Unit 52 Optical system (individual optical system) 53 Focusing mechanism 91 Control Unit 92 wafers 97 wafers

Claims

1. a support for supporting a wafer; an optical system that irradiates the wafer with linearly polarized light that is incident perpendicularly to a surface of the wafer; a first polarizing beam splitter that reflects light rays other than the linearly polarized light from the light rays reflected from the surface of the wafer; a first light receiving element that receives a component other than the linearly polarized light reflected by the first polarizing beam splitter and outputs an electrical signal according to the intensity of the component; a second polarizing beam splitter that reflects the linearly polarized light beam from the light beam that reflects from the surface of the wafer; a second light receiving element that receives the linearly polarized light component reflected by the second polarizing beam splitter and outputs an electrical signal according to the intensity of the component; a control unit that detects defects on the wafer based on the electrical signal of the first light receiving element and the electrical signal of the second light receiving element; A wafer inspection apparatus comprising:

2. The optical system includes an objective lens having an optical axis perpendicular to the surface of the wafer.

2. The wafer inspection device according to claim 1.

3. The support further includes a frame that holds a plurality of the optical systems that guide the plurality of light beams in parallel, and the first light receiving element and the second light receiving element that are combined with each of the optical systems.

2. The wafer inspection device according to claim 1.

4. a displacement mechanism for displacing the light beam relative to the wafer; 2. The wafer inspection device according to claim 1.

5. a focusing mechanism that detects the focus of the objective lens and drives the objective lens in the direction of the optical axis of the objective lens according to the detected focus; 3. The wafer inspection device according to claim 2.

6. The objective lens is formed with a numerical aperture that has a focal depth smaller than the height difference formed on the surface of the wafer.

6. The wafer inspection device according to claim 5.

7. When detecting the defect, the control unit compares registered data of the wafer that is assumed to be a non-defective product by the first light receiving element and the second light receiving element with actual measurement data of the wafer detected by the first light receiving element and the second light receiving element.

2. The wafer inspection device according to claim 1.

8. The registration data is created based on CAD data of the wafer.

8. The wafer inspection device according to claim 7.

9. A Faraday rotator is further provided between the first polarizing beam splitter and the second polarizing beam splitter, and a light beam transmitted through the first polarizing beam splitter passes through the Faraday rotator and enters the second polarizing beam splitter.

2. The wafer inspection device according to claim 1.

10. Further comprising a third light receiving element that receives the fluorescent light separated from components other than the linearly polarized light.

2. The wafer inspection device according to claim 1.

11. Further comprising a fourth light receiving element that receives the fluorescent light separated from the linearly polarized light component. The wafer inspection apparatus according to claim 10.

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