Wafer detection system and detection method

Abstract

The invention relates to a wafer detection system and a wafer detection method. The wafer detection system may include: a sample stage; a light source system; a first incident portion; an incoherent optical detection unit including: an objective lens, a first incoherent optical detection unit for detecting a first optical signal and outputting a first electrical signal; a second incoherent optical detection unit for detecting a second optical signal and outputting a second electrical signal; a third incoherent optical detection unit for detecting a third optical signal and outputting a third electrical signal; a fourth incoherent optical detection unit for detecting a fourth optical signal and outputting a fourth electrical signal; a coherent light detection unit including: a second differential interference prism; the differential interference detector is used for detecting an interference light signal which is reflected by the convex and / or concave defects of the wafer and generates interference, and outputting a fifth electric signal; and the controller is used for determining the defect of the wafer according to at least one or a combination of the first electric signal, the second electric signal, the third electric signal, the fourth electric signal and the fifth electric signal.

Description

Technical Field

[0001] This invention relates to a wafer inspection system and method, and more specifically to a wafer inspection system and method capable of detecting photoluminescence defects and scattering defects in wafers, and capable of distinguishing between protrusion and depression defects. Background Technology

[0002] Wafers are the fundamental material in semiconductor manufacturing, and their surface and internal defects can affect the performance and reliability of the final product. As the semiconductor industry continues to develop, the quality requirements for wafers are becoming increasingly stringent. By detecting wafer defects, problems can be identified in a timely manner during production, thereby improving wafer yield.

[0003] First-generation semiconductor materials are represented by silicon and germanium, and the inspection technology for first-generation semiconductor wafers is relatively mature. Third-generation semiconductor materials are represented by silicon carbide and gallium nitride, and the inspection technology for third-generation semiconductor wafers is still in the research and exploration stage. Taking silicon carbide wafers as an example, there are many types of wafer defects in silicon carbide wafers, such as particles, scratches, micropipes, basal plane dislocations, and stacking faults. Different types of defects can be detected using different technical methods.

[0004] Typically, defects such as particles and scratches can be detected by elastic scattering of incident light at the defect site. Defects that can be detected by elastic scattering are referred to as scattering defects. Additionally, various stacking faults and dislocation defects can be detected by photoluminescence at the defect site. Defects that can be detected by photoluminescence are referred to as photoluminescent defects.

[0005] In addition, another common type of defect in third-generation semiconductor wafers is the bump and depression defect. Bump and depression defects refer to protrusions and depressions formed on the wafer surface. Existing wafer inspection systems typically use elastic scattering to detect these defects. However, distinguishing between small-sized bumps and depressions, especially those smaller than micrometers, is quite difficult for existing wafer defect detection systems.

[0006] Patent document CN105493258A discloses a system and method for defect detection and photoluminescence measurement of samples, which can detect photoluminescence defects and scattering defects in wafers, and can distinguish between protrusions and depressions using elastic scattering. However, the system's ability to distinguish between protrusions and depressions is not ideal; it can only distinguish protrusions and depressions with a size of 5 micrometers or larger, while it cannot distinguish protrusions and depressions with smaller sizes.

[0007] Since distinguishing between bumps and depressions in a wafer is crucial for subsequent epitaxial processes in wafer fabrication, a wafer inspection system and method capable of better differentiating between these defects is needed. Ideally, this system and method should also be able to detect both photoluminescence and scattering defects simultaneously.

[0008] The information contained in the background section of this invention is only intended to enhance the understanding of the general background of this invention and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0009] The various aspects of the present invention are dedicated to solving the aforementioned problems in the prior art, and other technical problems not mentioned herein will be clearly understood by those skilled in the art through the following detailed description of the specification.

[0010] The purpose of this invention is to provide a wafer inspection system and method that can detect photoluminescence defects and scattering defects in wafers, and can distinguish between protrusion and depression defects.

[0011] According to one aspect of the present invention, a wafer inspection system may include: a sample stage, a light source system, a first incident section, an incoherent light detection section, a coherent light detection section, and a controller. The sample stage can be used to place a wafer. The light source system may include a first light source emitting a laser of a first wavelength and a second light source emitting a laser of a second wavelength, wherein the second wavelength is shorter than the first wavelength and can induce photoluminescence defects on the wafer to produce photoluminescence. The first incident section may be arranged downstream of the light source system and includes: a first differential interference prism, which is arranged between the first light source and the wafer, for spatially splitting the laser emitted from the first light source into two laser beams with an angle between them to irradiate the wafer; the incoherent light detection section... The photodetector can be arranged downstream of the optical path relative to the first incident portion and includes: an objective lens disposed above the wafer for receiving light scattered by scattering defects of the wafer and photoluminescence generated by photoluminescence defects of the wafer; a first incoherent photodetector disposed downstream of the objective lens for detecting a first optical signal of a first wavelength range emitted from a second light source and generated by a first photoluminescence defect of the wafer, and outputting a first electrical signal; a second incoherent photodetector disposed downstream of the first incoherent photodetector for detecting a second optical signal of a second wavelength emitted from the second light source and scattered by scattering defects of the wafer, and outputting a second electrical signal; and a third incoherent photodetector disposed downstream of the second incoherent photodetector. A coherent optical detector is arranged downstream of the optical path to detect a third optical signal in a second wavelength range emitted from a second light source and generated by a second photoluminescence defect on the wafer, and outputs a third electrical signal; and a fourth incoherent optical detector, arranged downstream of the third incoherent optical detector, to detect a fourth optical signal in a first wavelength range emitted from a first light source and scattered by a scattering defect on the wafer, and outputs a fourth electrical signal; the coherent optical detector may be arranged downstream of the optical path relative to the first incident part and includes: a second differential interference prism, arranged symmetrically with respect to the first differential interference prism relative to the wafer, for spatially combining two laser beams emitted from the first differential interference prism and reflected by the wafer into a single laser beam. The controller is configured to receive the first electrical signal, the second electrical signal, the third electrical signal, the fourth electrical signal, and the fifth electrical signal, and to determine the defects present in the wafer based on at least one or a combination of the first electrical signal, the second electrical signal, the third electrical signal, the fourth electrical signal, and the fifth electrical signal; wherein a laser of a first wavelength emitted from a first light source is incident on the wafer at a first predetermined angle after passing through a first incident portion.

[0012] Preferably, the first incident portion may further include: a half-wave plate and a first lens. The half-wave plate may be arranged between the first light source and the first differential interference prism. By adjusting the half-wave plate, the polarization direction of the first wavelength laser emitted from the first light source is matched with the optical axis direction of the first differential interference prism. The first lens may be arranged between the first differential interference prism and the wafer to make the two laser beams with an angle become two parallel laser beams and focus on the wafer.

[0013] Preferably, the coherent light detection unit may further include: a second lens and an analyzer, wherein the second lens may be arranged symmetrically with respect to the wafer with respect to the first lens, so as to collimate the two parallel diverging laser beams emitted from the first light source and reflected by the wafer; the analyzer may be arranged between the second differential interference prism and the differential interference detector, and the contrast of the interference light signal of the laser beam emitted from the second differential interference prism detected by the differential interference detector is maximized by adjusting the analyzer.

[0014] Preferably, the wafer inspection system may further include a second incident section, which may include at least one reflector and a third lens. The at least one reflector may be arranged between the second light source and the wafer so that a second wavelength laser emitted from the second light source illuminates the wafer at a second predetermined angle. The third lens may be arranged between the second light source and the wafer so that the second wavelength laser emitted from the second light source is focused on the wafer.

[0015] Preferably, the incoherent light detector may further include an aperture, which is arranged between the objective lens and the first incoherent light detector for receiving light emitted from the objective lens and filtering stray light.

[0016] Preferably, the first incoherent light detection unit may include: a first dichroic mirror, a first pinhole, a first filter, and a first photomultiplier tube detector. The first dichroic mirror may be arranged downstream of the optical path relative to the aperture, for reflecting light with wavelengths less than or equal to a first wavelength and transmitting light with wavelengths greater than the first wavelength in the light filtered by the aperture. The first pinhole may be arranged downstream of the optical path relative to the first dichroic mirror, for receiving light transmitted through the first dichroic mirror and filtering stray light. The first filter may be arranged downstream of the optical path relative to the first pinhole, for filtering out light in a first wavelength range from the light received by the first pinhole. The first photomultiplier tube detector may be arranged downstream of the optical path relative to the first filter, for detecting the first optical signal in the first wavelength range filtered by the first filter and outputting a first electrical signal.

[0017] Preferably, the second incoherent light detection unit may include: a second dichroic mirror, a second pinhole, a second filter, and a second photomultiplier tube detector. The second dichroic mirror may be arranged downstream of the first dichroic mirror in the optical path to reflect light with wavelengths less than a third wavelength and transmit light with wavelengths greater than or equal to the third wavelength, wherein the third wavelength is shorter than the first wavelength and longer than the second wavelength. The second pinhole may be arranged downstream of the second dichroic mirror in the optical path to receive light reflected by the second dichroic mirror and filter stray light. The second filter may be arranged downstream of the second pinhole in the optical path to filter out light of the second wavelength from the light received by the second pinhole. The second photomultiplier tube detector may be arranged downstream of the second filter in the optical path to detect the second optical signal of the second wavelength filtered by the second filter and output a second electrical signal.

[0018] Preferably, the third incoherent light detection unit may include: a third dichroic mirror, a third pinhole, a third filter, and a third photomultiplier tube detector. The third dichroic mirror may be arranged downstream of the second dichroic mirror in the optical path to reflect light with wavelengths less than a fourth wavelength and transmit light with wavelengths greater than or equal to the fourth wavelength, wherein the fourth wavelength is shorter than the first wavelength and longer than the third wavelength. The third pinhole may be arranged downstream of the third dichroic mirror in the optical path to receive light reflected by the third dichroic mirror and filter stray light. The third filter may be arranged downstream of the third pinhole in the optical path to filter out light in the second wavelength range from the light received by the third pinhole. The third photomultiplier tube detector may be arranged downstream of the third filter in the optical path to detect the third optical signal in the second wavelength range filtered by the third filter and output a third electrical signal.

[0019] Preferably, the fourth incoherent light detection unit may include: a fourth pinhole, a fourth filter, and a fourth photomultiplier tube detector. The fourth pinhole may be arranged downstream of the optical path relative to the third dichroic mirror to receive light transmitted through the third dichroic mirror and filter stray light. The fourth filter may be arranged downstream of the optical path relative to the fourth pinhole to filter out light of the first wavelength from the light received by the fourth pinhole. The fourth photomultiplier tube detector may be arranged downstream of the optical path relative to the fourth filter to detect the fourth optical signal of the first wavelength filtered out by the fourth filter and output a fourth electrical signal.

[0020] Preferably, the first predetermined angle can be in the range of 45° to 80°, and the second predetermined angle can be in the range of 2° to 5°.

[0021] Preferably, the wafer inspection system may further include: an angle adjustment mechanism disposed on the first differential interference prism and the second differential interference prism to change the deflection angle of the first differential interference prism and the second differential interference prism.

[0022] Preferably, the angle adjustment mechanism may include: a first adjustment plate, a second adjustment plate, and a third adjustment plate. The first adjustment plate may be fixedly connected to the housing of the wafer inspection system so that it will not undergo angular displacement relative to the optical path during adjustment. The second adjustment plate may be used to mount a first differential interference prism or a second differential interference prism. The third adjustment plate may be disposed between the first adjustment plate and the second adjustment plate, and the third adjustment plate may be connected to the first adjustment plate with relative angular displacement on one side and to the second adjustment plate with relative angular displacement on the other side.

[0023] Preferably, the third adjusting plate may have a first surface, a second surface, a third surface, and a fourth surface connected in sequence. The first adjusting plate has a first thickening groove at a position corresponding to the first surface, and the first surface of the third adjusting plate is connected to the first thickening groove, allowing the first adjusting plate to generate angular displacement relative to the third adjusting plate in a first direction. The second adjusting plate has a second thickening groove at a position corresponding to the second surface, and the second surface of the third adjusting plate is connected to the second thickening groove, allowing the second adjusting plate to generate angular displacement relative to the third adjusting plate in a second direction. A first inclined surface inclined towards the first adjusting plate is provided in a first region of the third surface of the third adjusting plate, and a second inclined surface inclined towards the second adjusting plate is provided in a second region of the third surface of the third adjusting plate. A mounting bracket is fixedly connected to the third region of the third surface of the third adjusting plate. A first adjusting bolt is installed on the mounting bracket at a position corresponding to the first inclined surface, and a second adjusting bolt is installed on the mounting bracket at a position corresponding to the second inclined surface. A first adjusting bead is provided between the first adjusting bolt and the first inclined surface, and a second adjusting bead is provided between the second adjusting bolt and the second inclined surface. By rotating the first adjusting bolt in the first rotational direction, the first adjusting bolt is displaced towards the first adjusting bead to compress the first adjusting bead, causing the first adjusting bead to displace along the first inclined plane to push the first adjusting plate to produce an angular displacement relative to the third adjusting plate in the first direction. By rotating the second adjusting bolt in the first rotational direction, the second adjusting bolt is displaced towards the second adjusting bead to compress the second adjusting bead, causing the second adjusting bead to displace along the second inclined plane to push the second adjusting plate to produce an angular displacement relative to the third adjusting plate in the second direction.

[0024] Preferably, the portion of the first adjusting bead that contacts the first inclined surface can be configured as a cutting plane to achieve surface contact between the first adjusting bead and the first inclined surface; the first adjusting plate is provided with a first slide rail at a position corresponding to the first adjusting bead, so that the first adjusting bead can slide along the first slide rail when pushing the first adjusting plate; the end of the first adjusting bolt that contacts the first adjusting bead is configured as a concave surface. Similarly, the portion of the second adjusting bead that contacts the second inclined surface can be configured as a cutting plane to achieve surface contact between the second adjusting bead and the second inclined surface; the second adjusting plate is provided with a second slide rail at a position corresponding to the second adjusting bead, so that the second adjusting bead can slide along the second slide rail when pushing the second adjusting plate; the end of the second adjusting bolt that contacts the second adjusting bead is configured as a concave surface.

[0025] According to another aspect of the present invention, a method for wafer inspection using a wafer inspection system may include: placing a wafer on a sample stage; irradiating the wafer using a light source system; automatically focusing the wafer using an autofocus system; controlling the sample stage and the housing of the wafer inspection system to move in a predetermined pattern to perform a spiral scan of the wafer; controlling a coherent light detection unit and an incoherent light detection unit to inspect the wafer; wherein the incoherent light detection unit is used to detect scattering defects and photoluminescence defects of the wafer; and the coherent light detection unit is used to detect bump and depression defects of the wafer.

[0026] The wafer inspection system and method according to exemplary embodiments of the present invention can detect photoluminescence defects, scattering defects, and protrusion and depression defects on a wafer through a single inspection of a detection location. Furthermore, the wafer inspection system and method according to exemplary embodiments of the present invention can distinguish between protrusion and depression defects with sizes as small as micrometers or even nanometers in the wafer, significantly improving the resolution of small-sized (e.g., below 5 micrometers) protrusion and depression defects. Moreover, the wafer inspection system and method according to exemplary embodiments of the present invention can utilize the combination of signals output from various detectors to improve the detection accuracy of wafer defects. Attached Figure Description

[0027] The above and other objects, features, and advantages of the invention will become clearer from the following detailed description presented in conjunction with the accompanying drawings, in which:

[0028] Figure 1 A schematic diagram illustrating a wafer inspection system according to an exemplary embodiment of the present invention;

[0029] Figure 2 A schematic diagram illustrating a position-sensitive detector according to an exemplary embodiment of the present invention;

[0030] Figure 3A schematic diagram illustrating the detection of protrusions and depressions according to an exemplary embodiment of the present invention;

[0031] Figure 4 A configuration diagram of a wafer inspection system according to an exemplary embodiment of the present invention is shown;

[0032] Figure 5 This is a first schematic diagram illustrating an angle adjustment mechanism for adjusting a differential interference prism according to an exemplary embodiment of the present invention;

[0033] Figure 6 This is a second schematic diagram illustrating an angle adjustment mechanism for adjusting a differential interference prism according to an exemplary embodiment of the present invention;

[0034] Figure 7 A third schematic diagram illustrating an angle adjustment mechanism for adjusting a differential interference prism according to an exemplary embodiment of the present invention;

[0035] Figure 8 A flowchart illustrating a wafer inspection method according to an exemplary embodiment of the present invention is provided. Detailed Implementation

[0036] Various embodiments of the wafer inspection system according to exemplary embodiments of the present invention will now be described with reference to the accompanying drawings.

[0037] Figure 1 This is a schematic diagram illustrating a wafer inspection system according to an exemplary embodiment of the present invention.

[0038] like Figure 1 As shown, a wafer inspection system according to an exemplary embodiment of the present invention may include: a sample stage 100, a light source system 200, a first incident section 300, a second incident section 400, an incoherent light detection section 500, a coherent light detection section 600, an autofocus section 700, and a controller 800.

[0039] The sample stage 100 may include a platform 101 and a drive motor (not shown), wherein the platform 101 is used to place the wafer to be tested, and the drive motor is used to rotate the platform 101 in a predetermined pattern under the control of the controller 800.

[0040] The light source system 200 may include a first light source 201 and a second light source 202.

[0041] The first light source 201 can emit linearly polarized laser light of a first wavelength. Preferably, the first wavelength can be 405 nm, and light of this wavelength will not cause photoluminescence defects on the wafer to produce photoluminescence when it shines on it.

[0042] The second light source 202 can emit laser light of a second wavelength. Preferably, the second wavelength can be 355 nm. When light of this wavelength shines on the wafer, it can cause photoluminescence defects on the wafer to produce photoluminescence, thereby generating photoluminescent light of a different wavelength than the first and second wavelengths.

[0043] Furthermore, the light source system 200 may include a first laser monitoring unit 203 and a second laser monitoring unit 204. The first laser monitoring unit 203 may, for example, consist of a beam splitter 203a and a diode 203b. The second laser monitoring unit 204 may, for example, consist of a beam splitter 204a and a diode 204b. The first laser monitoring unit 203 can be used to monitor the laser power emitted by the first light source 201 to determine whether the first light source 201 is operating normally. The second laser monitoring unit 204 can be used to monitor the laser power emitted by the second light source 202 to determine whether the second light source 202 is operating normally.

[0044] The first incident portion 300 can be arranged downstream of the optical path relative to the first laser monitoring unit 203. Here, downstream refers to the side downstream of the direction of light transmission. The first incident portion 300 can obliquely incident a first wavelength laser emitted from the first light source 201 onto the wafer at a first predetermined angle. Preferably, the first predetermined angle can be in the range of 45° to 80°. The first incident portion 300 may include: a half-wave plate 301, a reflector 302, a first differential interference prism reflector 302, and a lens 304.

[0045] Specifically, the half-wave plate 301 can be arranged downstream of the optical path relative to the first laser monitoring unit 203. The half-wave plate 301 can change the polarization direction of the linearly polarized laser.

[0046] The reflector 302 can be arranged downstream of the half-wave plate 301 in the optical path. The reflector 302 can change the direction of the laser emitted from the half-wave plate 301, so that the laser propagates in the direction of the first differential interference prism 303.

[0047] The first differential interference prism 303 can be, for example, a Nomarski prism. The first differential interference prism 303 can be arranged downstream of the optical path relative to the reflecting mirror 302. The first differential interference prism 303 can spatially split a linearly polarized laser of a first wavelength emitted from the first light source 201 into two laser beams with an angle between them, for use in coherent detection of the two optical signals. When the polarization direction of the linearly polarized laser of the first wavelength emitted from the first light source 201 matches the direction of the optical axis of the first differential interference prism 303, the two split linearly polarized laser beams have the same intensity, thus improving the contrast during interference of the two linearly polarized laser beams.

[0048] To match the polarization direction of the linearly polarized laser of the first wavelength emitted from the first light source 201 with the optical axis of the first differential interference prism 303, a half-wave plate 301 is placed between the first light source 201 and the first differential interference prism 303. By adjusting the half-wave plate 301, the polarization direction of the linearly polarized laser of the first wavelength emitted from the first light source 201 can be matched with the optical axis of the first differential interference prism 303.

[0049] The first differential interference prism 303 can be designed to split a linearly polarized laser beam incident on it into two beams with an angle between them, approximately in the range of 0.01° to 0.02°. Thus, the two beams are spatially separated by a distance of approximately a few micrometers.

[0050] Besides controlling the angle between two laser beams split by a differential interference prism through its design, the angle between the two split laser beams can also be controlled by adjusting the angle at which the laser beam is incident on the differential interference prism. To adjust the angle at which the laser beam is incident on the differential interference prism, the wafer inspection system according to an exemplary embodiment of the present invention is provided with an angle adjustment mechanism for adjusting the deflection angle of the differential interference prism. By precisely controlling the angle between the two split laser beams, the contrast of the detected interference light signal can be maximized, which will be discussed later in conjunction with... Figures 5 to 7 The angle adjustment mechanism is described in detail.

[0051] Lens 304 can be arranged downstream of the optical path relative to the first differential interference prism 303. The two laser beams with an angle emitted from the first differential interference prism 303 become two parallel laser beams after passing through lens 304 and are focused on the wafer.

[0052] The second incident portion 400 can be arranged downstream of the optical path relative to the second laser monitoring unit 204. The second incident portion 400 allows a second wavelength laser emitted from the second light source 202 to be obliquely incident on the wafer at a second predetermined angle θ. Preferably, the second predetermined angle can be in the range of 2° to 5°. The second incident portion 400 may include: a reflector 401, a reflector 402, a lens 403, and a reflector 404.

[0053] Specifically, reflectors 401 and 402 can be arranged sequentially downstream of the optical path relative to the second laser monitoring unit 204. Reflectors 401 and 402 can change the direction of the second wavelength laser emitted from the second laser monitoring unit 204, so that the second wavelength laser is transmitted towards the lens 403.

[0054] Lens 403 can be arranged downstream of the optical path relative to mirror 402. The second wavelength laser emitted from the second light source 202 is converged and focused onto the wafer when passing through lens 403.

[0055] Reflector 404 can be arranged downstream of lens 403 in the optical path. In an exemplary embodiment, the laser emitted from the second light source 202 is reflected by reflectors 401 and 402 and transmitted through lens 403, becoming a horizontally propagating laser. In this case, if reflector 404 is set to make an angle α of 45° with the vertical direction, the laser reflected by reflector 404 will be incident perpendicularly on the wafer. The laser incident perpendicularly on the wafer will be reflected by the wafer and re-incidentally on reflector 404, returning to the second light source 202 along the same optical path as from the second light source 202 to reflector 404, thereby damaging the second light source 202.

[0056] To avoid damaging the second light source 202, the angle α between the reflector 404 and the vertical direction can be set to a value other than 45°. Accordingly, the laser emitted from the second light source 202, after being reflected by the reflector 404, can be incident on the wafer at a second predetermined angle θ, non-perpendicularly. According to the principle of reflection, the relationship between the angle α and the second predetermined angle θ can be expressed as: If the second predetermined angle θ is in the range of 2° to 5°, then correspondingly, the included angle α can be in the range of 42.5° to 44°. That is, the reflector 404 can be set to have an angle α with the vertical direction in the range of 42.5° to 44°.

[0057] By setting the included angle α to a value other than 45°, the laser light incident on the wafer after being reflected by the reflector 404 cannot return to the second light source 202 along the same path, thereby preventing damage to the second light source 202. Therefore, the optical isolator used to protect the second light source 202 can be omitted from the optical path from the second light source 202 to the wafer.

[0058] The first incident section 300 and the second incident section 400 can be arranged such that light emitted from the first light source 201 and the second light source 202 is focused onto the same position on the wafer, thereby detecting scattering defects, protrusion and depression defects, and photoluminescence defects that may exist at the focal point.

[0059] The incoherent light detection unit 500 can be arranged downstream of the first incident part 300 and the second incident part 400 in the optical path. The incoherent light detection unit 500 can detect light signals scattered by scattering defects of the wafer and photoluminescence signals generated by photoluminescence defects of the wafer. The incoherent light detection unit 500 may include: an objective lens 501, a mirror 502, an aperture 503, a first incoherent light detection unit 510, a second incoherent light detection unit 520, a third incoherent light detection unit 530, and a fourth incoherent light detection unit 540.

[0060] Specifically, objective lens 501 can be positioned above the wafer to receive light scattered by scattering defects of the wafer and photoluminescence generated by photoluminescence defects of the wafer.

[0061] The reflector 502 can be arranged downstream of the objective lens 501 in the optical path. The reflector 502 can change the direction of the light emitted from the objective lens 501, so that the light emitted from the objective lens 501 is transmitted in the direction of the aperture 503.

[0062] The aperture 503 can be arranged downstream of the optical path relative to the mirror 502. The aperture 503 can receive the light emitted from the objective lens 501 and reflected by the mirror 502, and filter stray light.

[0063] A linearly polarized laser of a first wavelength emitted from the first light source 201 can irradiate the wafer at a first predetermined angle via the first incident section 300. When scattering defects exist in the wafer, the laser emitted from the first light source 201 and irradiating the wafer's scattering defects via the first incident section 300 will undergo elastic scattering. Furthermore, the laser emitted from the first light source 201 and irradiating the wafer via the first incident section 300 will be reflected, and when bumps and / or depressions exist in the wafer, there will be a phase difference between the two reflected beams.

[0064] A second wavelength laser emitted from the second light source 202 can irradiate the wafer via the second incident section 400. When scattering defects exist in the wafer, the laser emitted from the second light source 202 and irradiating the wafer's scattering defects via the second incident section 400 will undergo elastic scattering. Furthermore, when photoluminescence defects exist in the wafer, the laser emitted from the second light source 202 and irradiating the wafer's photoluminescence defects via the second incident section 400 will produce photoluminescence.

[0065] A laser beam of a first wavelength emitted from the first light source 201 can be obliquely incident on the wafer at an angle of approximately 45° to 80° via the first incident section 300. Correspondingly, the light reflected from the wafer will exit at an angle of approximately 45° to 80°, and the exiting light cannot be received by the objective lens 501 with a small numerical aperture positioned above the wafer. Furthermore, a laser beam of a second wavelength emitted from the second light source 202 can be obliquely incident on the wafer at an angle of approximately 2° to 5° via the second incident section 400. Correspondingly, the light reflected from the wafer will exit at an angle of approximately 2° to 5°, and the exiting light will be incident on the reflector 404 and reflected again by the reflector 404, instead of being received by the objective lens 501 positioned above the wafer.

[0066] Therefore, the light received by and emitted from objective lens 501 can include: light of a first wavelength emitted from first light source 201 and scattered by scattering defects in the wafer; light of a second wavelength emitted from second light source 202 and scattered by scattering defects in the wafer; and photoluminescence emitted from second light source 202 and generated by photoluminescence defects in the wafer. The incoherent light detection unit 500 can detect the light emitted from objective lens 501.

[0067] The first incoherent light detector 510, the second incoherent light detector 520, the third incoherent light detector 530, and the fourth incoherent light detector 540 of the incoherent light detector 500 will be described in detail below.

[0068] When photoluminescence defects exist in a wafer, laser light incident on these defects will produce photoluminescence due to the photoluminescence effect. Different types of photoluminescence defects produce photoluminescence with different wavelengths, and the resulting photoluminescence does not correspond to a single wavelength but rather has different wavelength ranges depending on the type of photoluminescence defect. In an exemplary embodiment, photoluminescence in a first wavelength range can be detected by a first incoherent photodetector 510, and photoluminescence in a second wavelength range can be detected by a third incoherent photodetector 530. Preferably, the first wavelength range can be from 410 nm to 440 nm, and the second wavelength range can be from 362 nm to 396 nm.

[0069] In an exemplary embodiment, the first incoherent light detector 510 may be arranged downstream of the optical path relative to the aperture 503. The first incoherent light detector 510 may include: a first dichroic mirror 511, a first pinhole 512, a first filter 513, and a first photomultiplier tube detector 514.

[0070] Dichroic mirrors can separate light according to wavelength. By coating a filter film and an anti-reflection film on both sides of the dichroic mirror, it can exhibit high transmittance or high reflectance characteristics for light of different wavelengths.

[0071] Specifically, the first dichroic mirror 511 can be arranged downstream of the optical path relative to the aperture 503. The first dichroic mirror 511 can reflect light with wavelengths less than or equal to the first wavelength that is filtered by the aperture 503, and transmit light with wavelengths greater than the first wavelength.

[0072] The first pinhole 512 can be arranged downstream of the first dichroic mirror 511 in the optical path. The first pinhole 512 can have a smaller aperture than the aperture stop 503. The first pinhole 512 can receive light transmitted through the first dichroic mirror 511 and filter stray light. Thus, light with wavelengths greater than the first wavelength in the light received by the objective lens 501 can pass through the first pinhole 512.

[0073] The first filter 513 may be disposed downstream of the first pinhole 512 in the optical path. The first filter 513 may be a broadband filter and filter out light in a first wavelength range (i.e., 410 nm to 440 nm) from the light received from the first pinhole 512.

[0074] The first photomultiplier tube detector 514 can be arranged downstream of the first filter 513 in the optical path. The first photomultiplier tube detector 514 can detect a first optical signal within a first wavelength range filtered by the first filter 513. The first photomultiplier tube detector 514 can convert the received first optical signal within the first wavelength range into a first electrical signal and send the converted first electrical signal to the controller 800. The controller 800 can process the received first electrical signal using an image processing algorithm.

[0075] Therefore, the laser of the second wavelength emitted from the second light source 202 can irradiate the wafer at a second predetermined angle via the second incident section 400. When a first photoluminescence defect exists in the wafer, the first photoluminescence defect absorbs the laser of the second wavelength and radiates photoluminescence within a first wavelength range. The radiated photoluminescence within the first wavelength range is received by the first incoherent photodetector 510. The photoluminescence signal within the first wavelength range is detected by the first photomultiplier tube detector 514 of the first incoherent photodetector 510.

[0076] The controller 800 can detect a first photoluminescence defect present in the wafer using only the first electrical signal output from the first incoherent photodetector 510. Preferably, the first photoluminescence defect may include stacking faults, strip stacking faults, etc. Alternatively, the controller 800 can detect stacking faults in the first photoluminescence defect using a combination of the electrical signals output from the first incoherent photodetector 510 and the second incoherent photodetector 520, which will be described below.

[0077] In an exemplary embodiment, the second incoherent light detector 520 may be arranged downstream of the first incoherent light detector 510 in the optical path. The second incoherent light detector 520 may include a second dichroic mirror 521, a second pinhole 522, a second filter 523, and a second photomultiplier tube detector 524.

[0078] Specifically, the second dichroic mirror 521 can be arranged downstream of the first dichroic mirror 511 in the optical path. The second dichroic mirror 521 can reflect light with wavelengths shorter than a third wavelength and transmit light with wavelengths greater than or equal to the third wavelength after the light is reflected by the first dichroic mirror 511, wherein the third wavelength is shorter than the first wavelength and longer than the second wavelength. Preferably, the third wavelength can be 360 ​​nm.

[0079] The second pinhole 522 can be arranged downstream of the optical path relative to the second dichroic mirror 521. The second pinhole 522 can have a smaller aperture than the aperture stop 503. The second pinhole 522 can receive light reflected by the second dichroic mirror 521 and filter stray light. Thus, light with wavelengths shorter than the third wavelength in the light received by the objective lens 501 can pass through the second pinhole 522.

[0080] The second filter 523 can be arranged downstream of the optical path relative to the second pinhole 522. The second filter 523 can be a narrowband filter and filters out light of a second wavelength (i.e., 355 nm) from the light received from the second pinhole 522.

[0081] The second photomultiplier tube detector 524 can be arranged downstream of the second filter 523 in the optical path. The second photomultiplier tube detector 524 can detect the second optical signal of the second wavelength filtered by the second filter 523. The second photomultiplier tube detector 524 can convert the received second optical signal of the second wavelength into a second electrical signal and send the converted second electrical signal to the controller 800. The controller 800 can process the received second electrical signal using an image processing algorithm.

[0082] Therefore, the second wavelength laser emitted from the second light source 202 can irradiate the wafer at a second predetermined angle via the second incident section 400. When scattering defects exist in the wafer, these defects cause elastic scattering of the second wavelength laser irradiating the wafer, and the scattered light is received by the second incoherent light detection section 520. The second photomultiplier tube detector 524 of the second incoherent light detection section 520 detects the second wavelength scattered light signal.

[0083] In an exemplary embodiment, the third incoherent light detector 530 may be arranged downstream of the second incoherent light detector 520 in the optical path. The third incoherent light detector 530 may include a third dichroic mirror 531, a third pinhole 532, a third filter 533, and a third photomultiplier tube detector 534.

[0084] Specifically, the third dichroic mirror 531 can be arranged downstream of the second dichroic mirror 521 in the optical path. The third dichroic mirror 531 can reflect light with wavelengths shorter than the fourth wavelength after it has been reflected by the second dichroic mirror 521, and transmit light with wavelengths greater than or equal to the fourth wavelength, wherein the fourth wavelength is shorter than the first wavelength and longer than the third wavelength. Preferably, the fourth wavelength can be 400 nm.

[0085] The third pinhole 532 can be arranged downstream of the optical path relative to the third dichroic mirror 531. The third pinhole 532 can have a smaller aperture than the aperture stop 503. The third pinhole 532 can receive light reflected by the third dichroic mirror 531 and filter stray light. Thus, light with a wavelength greater than or equal to the third wavelength and less than the fourth wavelength in the light received by the objective lens 501 can pass through the third pinhole 532.

[0086] The third filter 533 can be disposed downstream of the optical path relative to the third pinhole 532. The third filter 533 can be a narrowband filter and filters out light in the second wavelength range (i.e., 362 nm to 396 nm) from the light received from the third pinhole 532.

[0087] The third photomultiplier tube detector 534 can be arranged downstream of the optical path relative to the third filter 533. The third photomultiplier tube detector 534 can detect the third optical signal within the second wavelength range filtered by the third filter 533. The third photomultiplier tube detector 534 can convert the received third optical signal within the second wavelength range into a third electrical signal and send the converted third electrical signal to the controller 800. The controller 800 can process the received third electrical signal using an image processing algorithm.

[0088] Therefore, the laser light of the second wavelength emitted from the second light source 202 can irradiate the wafer at a second predetermined angle via the second incident section 400. When a second photoluminescence defect exists in the wafer, the second photoluminescence defect absorbs the laser light of the second wavelength and radiates photoluminescence within the second wavelength range. The radiated photoluminescence within the second wavelength range is received by the third incoherent photodetector 530. The photoluminescence signal within the second wavelength range is detected by the third photomultiplier tube detector 534 of the third incoherent photodetector 530 to detect the second photoluminescence defect present in the wafer. Preferably, the second photoluminescence defect may include basal plane dislocations, grain boundaries, etc.

[0089] In an exemplary embodiment, the fourth incoherent light detector 540 may be arranged downstream of the third incoherent light detector 530 in the optical path. The fourth incoherent light detector 540 may include a mirror 541, a fourth pinhole 542, a fourth filter 543, and a fourth photomultiplier tube detector 544.

[0090] Specifically, the reflector 541 can be arranged downstream of the optical path relative to the third dichroic mirror 531. The reflector 541 can change the direction of the light transmitted through the third dichroic mirror 531, so that the light emitted from the third dichroic mirror 531 is transmitted in the direction of the fourth pinhole 542.

[0091] The fourth pinhole 542 can be arranged downstream of the reflector 541 in the optical path. The fourth pinhole 542 can have a smaller aperture than the aperture stop 503. The fourth pinhole 542 can receive light reflected by the reflector 541 and filter stray light. Thus, light with a wavelength greater than or equal to the fourth wavelength and less than or equal to the first wavelength in the light received by the objective lens 501 can pass through the fourth pinhole 542.

[0092] The fourth filter 543 can be disposed downstream of the optical path relative to the fourth pinhole 542. The fourth filter 543 can be a narrowband filter and filters out light of a first wavelength (i.e., 405 nm) from the light received from the fourth pinhole 542.

[0093] The fourth photomultiplier tube detector 544 can be arranged downstream of the optical path relative to the fourth filter 543. The fourth photomultiplier tube detector 544 can detect the fourth optical signal of the first wavelength filtered out by the fourth filter 543. The fourth photomultiplier tube detector 544 can convert the received fourth optical signal of the first wavelength into a fourth electrical signal and send the converted fourth electrical signal to the controller 800. The controller 800 can process the received fourth electrical signal using an image processing algorithm.

[0094] Therefore, linearly polarized laser light of the first wavelength emitted from the first light source 201 can irradiate the wafer at a first predetermined angle via the first incident section 300. When scattering defects exist in the wafer, the scattering defects cause elastic scattering of the laser light of the first wavelength irradiated onto the wafer, and the scattered light is received by the fourth incoherent light detection section 540. The scattered light signal of the first wavelength is detected by the fourth photomultiplier tube detector 544 of the fourth incoherent light detection section 540.

[0095] The controller 800 can detect scattering defects in the wafer by using the electrical signal output from either the second incoherent photodetector 520 or the fourth incoherent photodetector 540 alone, or by using a combination of the electrical signals output from the second incoherent photodetector 520 and the fourth incoherent photodetector 540.

[0096] To detect and differentiate between bumps and depressions on a wafer, particularly those with small dimensions (e.g., less than 5 micrometers), a wafer inspection system according to an exemplary embodiment of the present invention is provided with a coherent optical detection unit 600. The coherent optical detection unit 600 utilizes a coherent detection method based on the principle of light interference to distinguish between bumps and depressions in the wafer with dimensions as low as micrometers or even nanometers. Compared to existing wafer inspection systems capable of detecting bumps and depressions, the wafer inspection system according to an exemplary embodiment of the present invention can significantly improve the resolution of small-sized (e.g., less than 5 micrometers) bumps and depressions.

[0097] In an exemplary embodiment, the coherent light detector 600 may be arranged downstream of the optical path relative to the first incident portion 300. The coherent light detector 600 may include: a lens 601, a second differential interference prism 602, a reflector 603, an analyzer 604, a lens 605, and a differential interference detector 606.

[0098] Specifically, lens 601 can be arranged downstream of the wafer in the optical path, and symmetrically positioned relative to the wafer as lens 304 of the first incident section 300. After passing through lens 304 of the first incident section 300, the two parallel laser beams are reflected by the wafer and then incident on lens 601 of the coherent light detection section 600. Lens 601 can collimate the two parallel diverging laser beams and make them intersect in the second differential interference prism 602.

[0099] The second differential interference prism 602 can be arranged downstream of the lens 601 in the optical path, and symmetrically positioned relative to the wafer as the first differential interference prism 303 of the first incident section 300. The second differential interference prism 602 can be designed to have the same parameters as the first differential interference prism 303. The second differential interference prism 602 can spatially combine two laser beams emitted from the lens 601 into a single laser beam. Thus, the two converging laser beams emitted from the lens 601 can interfere within the second differential interference prism 602.

[0100] The reflector 603 can be arranged downstream of the optical path relative to the second differential interference prism 602. The reflector 603 can change the direction of the combined laser beam emitted from the second differential interference prism 602, so that the combined laser beam is transmitted towards the analyzer 604.

[0101] The analyzer 604 can be positioned downstream of the optical path relative to the mirror 603. When bumps and / or depressions exist in the wafer, the two laser beams emitted from the lens 601 will interfere in the second differential interference prism 602, and the differential interference detector 606 can detect the interference light signal. In this case, adjusting the analyzer 604 can maximize the contrast of the interference light signal detected by the differential interference detector 606.

[0102] Lens 605 can be positioned downstream of analyzer 604 in the optical path. Lens 605 can converge and focus the laser emitted from analyzer 604 onto differential interferometer detector 606.

[0103] The differential interferometer detector 606 can be positioned downstream of the lens 605 in the optical path. The differential interferometer detector 606 can detect the laser emitted from the lens 605. The differential interferometer detector 606 can convert the received interference light signal into a fifth electrical signal and send the converted fifth electrical signal to the controller 800. The controller 800 can process the received fifth electrical signal using an image processing algorithm.

[0104] Therefore, linearly polarized laser light of the first wavelength emitted from the first light source 201 can irradiate the wafer at a first predetermined angle via the first incident section 300. When bumps and / or depressions exist in the wafer, the bumps and / or depressions cause the laser light irradiating the wafer to be reflected. The reflected light is received by the coherent light detection section 600 and interferes in the second differential interference prism 602 of the coherent light detection section 600. The interference light signal is detected by the differential interference detector 606 of the coherent light detection section 600 to detect the bumps and / or depressions present in the wafer.

[0105] In an exemplary embodiment, the autofocus unit 700 may include a beam splitter 701, a reflector 702, and a position-sensitive detector 703.

[0106] Specifically, beam splitter 701 can be arranged between analyzer 604 and lens 605. Beam splitter 701 can split the light emitted from analyzer 604 into two beams, one beam for detection by differential interferometer detector 606 and the other beam for detection by position-sensitive detector 703. As an example, the light transmitted by beam splitter 701 can be used for detection by differential interferometer detector 606, and the light reflected by beam splitter 701 can be used for detection by position-sensitive detector 703.

[0107] The reflector 702 can be arranged downstream of the beam splitter 701 in the optical path. The reflector 702 can change the direction of the light reflected by the beam splitter 701, so that the light reflected by the beam splitter 701 is transmitted in the direction of the position-sensitive detector 703.

[0108] Position-sensitive detector 703 can be arranged downstream of the optical path relative to reflector 702. Another beam of light reflected by beam splitter 701 can be incident on position-sensitive detector 703, which can use this other beam of light to autofocus the wafer. The method of autofocusing using position-sensitive detector is the same as existing autofocusing methods, and detailed description is omitted here.

[0109] In addition to autofocusing, the autofocus unit 700 can also be used to detect bumps and depressions on the wafer. Small bumps and depressions can be detected using the coherent light detection unit 600, while large bumps and depressions can be detected using the autofocus unit 700. Here, "small size" can refer to a size of 5 μm or less, and "large size" can refer to a size of 5 μm or more.

[0110] Figure 2 This is a schematic diagram illustrating a position-sensitive detector 703 according to an exemplary embodiment of the present invention.

[0111] like Figure 2 As shown, the position-sensitive detector 703 can be composed of four sensors S1, S2, S3, and S4. As an example, sensors S1, S2, S3, and S4 can be optical signal sensors. Each of sensors S1, S2, S3, and S4 converts the detected optical signal into an electrical signal, and the intensity I' of the converted electrical signal is proportional to the intensity I of the detected optical signal.

[0112] Specifically, when a laser of the first wavelength emitted from the first light source 201 is incident on a flat area of ​​the wafer surface through the first incident section 300, the laser is reflected by the wafer surface and incident on the beam splitter 701 of the autofocus section 700. The light reflected by the beam splitter 701 can then be incident on the position-sensitive detector 703. By adjusting the position-sensitive detector 703, the center of the light spot received by the position-sensitive detector 703 is positioned at the center O of the position-sensitive detector 703. At this time, the intensity of the electrical signal obtained by the conversion of sensors S1, S2, S3, and S4 can be expressed as I' S1 、I' S2 、I' S3 and I' S4 , and I' S1 、I' S2 、I' S3 and I' S4 The following relationship can be satisfied:

[0113] (I' S1 +I' S2 )-(I' S3 +I' S4 ) = 0

[0114] When a laser of a first wavelength emitted from the first light source 201 passes through the first incident part 300 and is incident on a protrusion or depression on the wafer surface, the intensity I' of the electrical signal obtained by the sensors S1, S2, S3, and S4 is... S1 、I' S2 、I' S3 and I' S4 The following relationship can be satisfied:

[0115] (I' S1 +I' S2 )-(I' S3 +I' S4 )≠0, or (I' S1 +I' S4 )-(I' S2 +I' S3 )≠0

[0116] Specifically, when there are radial protrusions or depressions on the wafer surface, I' S1 、I' S2 、I' S3 and I' S4 It can satisfy (I' S1 +I' S2 )-(I' S3 +I' S4 The relationship is ≠ 0. When there are circumferential protrusions or depressions on the wafer surface, I' S1 、I' S2 、I' S3 and I' S4 It can satisfy (I' S1 +I' S4 )-(I' S2 +I' S3 The relationship is that the electrical signal strength I' is not equal to 0. The position-sensitive detector 703 can detect the electrical signal strength I'. S1 、I' S2 、I' S3 and I' S4 The signal is sent to controller 800, which can then adjust the intensity I'. S1 、I' S2 、I' S3 and I' S4 Calculations are performed to determine the strength I' S1 、I' S2 、I' S3 and I' S4 The relationship that is satisfied. Therefore, the autofocus unit 700 can be used to detect large-sized protrusions and dents.

[0117] The mirrors included in the first incident section 300, the second incident section 400, the incoherent light detection section 500, the coherent light detection section 600, and the autofocus section 700 according to the exemplary embodiment are not mandatory, and the number of mirrors can be increased or decreased depending on the specific optical path arrangement.

[0118] The controller 800 can be electrically connected to the drive motor, light source system 200, first photomultiplier tube detector 514, second photomultiplier tube detector 524, third photomultiplier tube detector 534, fourth photomultiplier tube detector 544, differential interferometer detector 606, and position-sensitive detector 703 of the sample stage 100 to control these components. Here, "electrical connection" can refer to a wired network connection, such as via a network cable or serial cable, or a wireless network connection, such as via Wi-Fi or Bluetooth.

[0119] Furthermore, the wafer inspection system according to an exemplary embodiment of the present invention may further include a housing (not shown). The housing may be disposed above the wafer for housing the light source system 200, the first incident section 300, the second incident section 400, the incoherent light detection section 500, the coherent light detection section 600, and the autofocus section 700. The housing may have an exit window and an incident window. Laser emitted from the light source system 200 passes through the first incident section 300 and / or the second incident section 400 and exits through the exit window of the housing to irradiate the wafer. Scattered light and / or reflected light and / or photoluminescence caused by defects present in the wafer may enter the incoherent light detection section 500 and / or the coherent light detection section 600 and / or the autofocus section 700 through the incident window of the housing.

[0120] Furthermore, the housing may have a drive motor (not shown) for moving the housing. Under the control of the controller 800, the drive motor enables the housing to translate in a predetermined pattern along the radial direction of the wafer. Thus, a helical scanning of the wafer is achieved through the interaction of the rotation of the sample stage 100 and the translation of the housing.

[0121] Figure 3 This is a schematic diagram illustrating the detection of protrusions and depressions according to an exemplary embodiment of the present invention.

[0122] like Figure 3 As shown, Figure 3 The lower part shows the wafer surface S, which, from left to right, represents the case where the wafer surface S is a flat region A, the case where the wafer surface S has a protrusion B, and the case where the wafer surface S has a depression C. Figure 3The upper part shows the optical signal detected by the differential interference detector 606 when a laser of the first wavelength emitted from the first light source 201 is reflected by the wafer surface S and incident on the differential interference detector 606 of the coherent light detection unit 600.

[0123] The first light beam L1, emitted from the first light source 201 and incident on the first differential interference prism 303, is spatially split into a second beam L2 and a third beam L3 with an angle between them as it passes through the first differential interference prism 303. The second beam L2 and the third beam L3 with an angle between them become two parallel beams of light after passing through the lens 304.

[0124] Figure 3 The diagram shows that after the first beam L1 passes through the first differential interference prism 303 and the lens 304, it becomes the second beam L2 and the third beam L3. After being reflected by the wafer surface S, the second beam L2 and the third beam L3 pass through the lens 601 and the second differential interference prism 602, and then become the fourth beam L4.

[0125] When the second beam L2 and the third beam L3 are incident on a flat region A of the wafer surface S, they are reflected by the wafer surface S. No phase difference is generated between the second beam L2 and the third beam L3. The reflected second beam L2 and the third beam L3 are then incident on the second differential interference prism 602. Upon passing through the second differential interference prism 602, the reflected second beam L2 and the third beam L3 spatially combine into a fourth beam L4, which is ultimately incident on the differential interference detector 606. Since there is no phase difference between the second beam L2 and the third beam L3 after reflection, their interference intensity does not change within the second differential interference prism 602. Therefore, in all flat regions A of the wafer surface S, the differential interference detector 606 will detect... Figure 3 The same optical signal is shown at the top.

[0126] When the second beam L2 and the third beam L3 are incident on the protrusion B of the wafer surface S, the second beam L2 can illuminate the protrusion B, while the third beam L3 can illuminate the flat area A of the wafer surface S. Therefore, the second beam L2, reflected by the protrusion B, and the third beam L3, reflected by the flat area A, will have a phase difference Φ1, and this phase difference Φ1 is negative. Next, the reflected second beam L2 and the third beam L3 are incident on the second differential interference prism 602 and spatially combine into a fourth beam L4 as they pass through it. The fourth beam L4 is then incident on the differential interference detector 606. Because the second beam L2 and the third beam L3 have a phase difference Φ1 after reflection, the interference signal intensity of the second beam L2 and the third beam L3 will change within the second differential interference prism 602. Therefore, the differential interference detector 606 will detect... Figure 3 The first interference light signal shown at the top.

[0127] When the second beam L2 and the third beam L3 are incident on the depression C of the wafer surface S, the second beam L2 can illuminate the depression C of the wafer surface S, while the third beam L3 can illuminate the flat area A of the wafer surface S. Therefore, the second beam L2, reflected by the depression C of the wafer surface S, and the third beam L3, reflected by the flat area A of the wafer surface S, will have a phase difference Φ2, and this phase difference Φ2 is positive. Next, the reflected second beam L2 and the third beam L3 are incident on the second differential interference prism 602 and spatially combine into a fourth beam L4 as they pass through the second differential interference prism 602. The fourth beam L4 is finally incident on the differential interference detector 606. Because the second beam L2 and the third beam L3 have a phase difference Φ2 after reflection, the intensity of the interference signal changes between them in the second differential interference prism 602. Therefore, the differential interference detector 606 will detect... Figure 3 The second interference light signal shown at the top.

[0128] like Figure 3As shown above, since the phase difference Φ1 generated by the second beam L2 and the third beam L3 incident on the convex B has the opposite sign (representing the signs of positive and negative values) to the phase difference Φ2 generated by the second beam L2 and the third beam L3 incident on the concave C, the first interference light signal generated by the second beam L2 and the third beam L3 incident on the convex B is different from the second interference light signal generated by the second beam L2 and the third beam L3 incident on the concave C. For example, when the second beam L2 and the third beam L3 are incident on the convex B, the generated first interference light signal first shows a peak and then a trough; while when the second beam L2 and the third beam L3 are incident on the concave C, the generated second interference light signal first shows a trough and then a peak. Figure 3 The first and second interference light signals shown above are just examples. In order to facilitate the explanation that the interference light signals generated by the protrusions and depressions of the wafer are different, the protrusions and depressions are distinguishable.

[0129] Specifically, to determine the waveforms of the first and second interference optical signals generated by the bumps and depressions in the wafer, calibration can be performed using a reference sample before actual wafer inspection. After calibration, the wafer inspection system can distinguish between bumps and depressions based on the detected waveforms of the interference optical signals when inspecting the wafer.

[0130] The wafer inspection system according to an exemplary embodiment of the present invention can distinguish between protrusions and depressions in wafers with sizes as low as micrometers or even nanometers, significantly improving the resolution of small-sized (e.g., less than 5 micrometers) protrusions and depressions.

[0131] Figure 4 A configuration diagram of a wafer inspection system according to an exemplary embodiment of the present invention is shown.

[0132] like Figure 4 As shown, during the wafer inspection process, a laser of the second wavelength emitted from the second light source 202 can be incident on the first photoluminescence defect present in the wafer via the second incident part 400. The first photoluminescence defect can radiate photoluminescence in the first wavelength range. The radiated photoluminescence in the first wavelength range can be incident on the first incoherent light detection part 510. The first incoherent light detection part 510 can convert the first optical signal in the first wavelength range into a first electrical signal and send the first electrical signal to the controller 800.

[0133] Meanwhile, the laser of the second wavelength emitted from the second light source 202 can be incident on the scattering defects present in the wafer via the second incident section 400. The scattering defects can scatter the incident light, and the scattered light can be incident on the second incoherent light detection section 520. The second incoherent light detection section 520 can convert the second optical signal into a second electrical signal and send the second electrical signal to the controller 800.

[0134] Meanwhile, the laser of the second wavelength emitted from the second light source 202 can be incident on the second photoluminescence defect present in the wafer via the second incident section 400. The second photoluminescence defect can radiate photoluminescence in the second wavelength range. The radiated photoluminescence in the second wavelength range can be incident on the third incoherent photodetector 530. The third incoherent photodetector 530 can convert the third optical signal in the second wavelength range into a third electrical signal and send the third electrical signal to the controller 800.

[0135] Furthermore, the laser of the first wavelength emitted from the first light source 201 can be incident on the scattering defects present in the wafer via the first incident section 300. The scattering defects can scatter the incident light, and the scattered light can be incident on the fourth incoherent light detection section 540. The fourth incoherent light detection section 540 can convert the fourth optical signal into a fourth electrical signal and send the fourth electrical signal to the controller 800.

[0136] Meanwhile, a laser of the first wavelength emitted from the first light source 201 can be incident on a protrusion or depression defect present in the wafer via the first incident part 300. The protrusion or depression defect can reflect the incident light, and the reflected light can be incident on the coherent light detection part 600 and interfere in the coherent light detection part 600. The coherent light detection part 600 can convert the interference light signal into a fifth electrical signal and send the fifth electrical signal to the controller 800.

[0137] In one exemplary embodiment, the controller 800 can detect defects present in the wafer based on one of a first electrical signal, a second electrical signal, a third electrical signal, a fourth electrical signal, and a fifth electrical signal. As an example, the controller 800 can detect a first photoluminescence defect based on the first electrical signal, a scattering defect based on the second or fourth electrical signal, a second photoluminescence defect based on the third electrical signal, and bump and depression defects based on the fifth electrical signal.

[0138] In another exemplary embodiment, the controller 800 can detect defects present in the wafer based on a combination of two or more of a received first electrical signal, a second electrical signal, a third electrical signal, a fourth electrical signal, and a fifth electrical signal. As an example, the controller 800 can detect scattering defects based on a combination of the second and fourth electrical signals. Furthermore, the controller 800 can detect stacking faults in a first photoluminescence defect based on a combination of the first and second electrical signals.

[0139] The wafer inspection system according to an exemplary embodiment of the present invention can simultaneously detect photoluminescence defects, scattering defects, and protrusion and depression defects on a wafer using two light sources. Furthermore, the wafer inspection system according to an exemplary embodiment of the present invention can distinguish between protrusion and depression defects with dimensions as low as micrometers or even nanometers, significantly improving the resolution of small-sized (e.g., below 5 micrometers) protrusion and depression defects. Moreover, the wafer inspection system according to an exemplary embodiment of the present invention can utilize the combination of signals output from various detectors to improve the detection accuracy of wafer defects.

[0140] Figures 5 to 7 This is a schematic diagram illustrating an angle adjustment mechanism 1000 for adjusting a differential interference prism according to an exemplary embodiment of the present invention. The angle adjustment mechanism 1000 according to an exemplary embodiment of the present invention can be applied to a first differential interference prism 303 and a second differential interference prism 602 in a wafer inspection system according to an exemplary embodiment of the present invention. The angle adjustment mechanism 1000 according to an exemplary embodiment of the present invention can adjust the deflection angles of the first differential interference prism 303 and the second differential interference prism 602, respectively. Here, the deflection angle can refer to... Figure 5 The horizontal and vertical deflection angles are shown. This allows for precise control of the angle between the two laser beams emitted from the first differential interference prism 303. By adjusting the second differential interference prism 602 in accordance with the first differential interference prism 303, the two laser beams can be precisely combined into one.

[0141] Figure 5 A schematic diagram of an angle adjustment mechanism 1000 engaged with a first differential interference prism 303 or a second differential interference prism 602 is shown. Figure 6 The angle adjustment mechanism 1000 is shown in cross-section with the removal of the mounting bracket 1008 and the first adjusting bolt 1009 and the second adjusting bolt 1010. Figure 7 An angle adjustment mechanism 1000 is shown that removes the mounting bracket 1008, the first adjusting bolt 1009, and the second adjusting bolt 1010.

[0142] like Figures 5 to 7As shown, the angle adjustment mechanism 1000 may include a first adjustment plate 1001, a second adjustment plate 1002, and a third adjustment plate 1003. Preferably, the first adjustment plate 1001, the second adjustment plate 1002, and the third adjustment plate 1003 may be integrally formed. The central region of the first adjustment plate 1001, the second adjustment plate 1002, and the third adjustment plate 1003 may have a through hole for light transmission. In addition, the outer peripheral region of the first adjustment plate 1001, the second adjustment plate 1002, and the third adjustment plate 1003 may have multiple mounting holes for mounting the adjustment plates.

[0143] The first adjustment plate 1001 can be fixedly connected to the housing of the wafer inspection system. Therefore, when the deflection angle of the differential interference prism is adjusted using the angle adjustment mechanism 1000, the first adjustment plate 1001 will not undergo angular displacement relative to the optical path.

[0144] The second adjustment plate 1002 can be used to mount the first differential interference prism 303 or the second differential interference prism 602. Specifically, the second adjustment plate 1002 can be engaged with the frame F used to mount the first differential interference prism 303 or the second differential interference prism 602.

[0145] The third adjusting plate 1003 can be disposed between the first adjusting plate 1001 and the second adjusting plate 1002. The third adjusting plate 1003 is angularly connected to the first adjusting plate 1001 via one side and angularly connected to the second adjusting plate 1002 via the other side. One side of the third adjusting plate 1003 can be as follows: Figure 5 As shown on the right side, the other side of the third adjustment plate 1003 can be as follows: Figure 5 The left side is shown.

[0146] The third adjustment plate 1003 may have a first surface 1003a, a second surface 1003b, a third surface 1003c, and a fourth surface 1003d connected in sequence.

[0147] The first adjusting plate 1001 may have a first thickening groove 1004 provided at a position corresponding to the first surface 1003a of the third adjusting plate 1003. The first surface 1003a of the third adjusting plate 1003 may be connected to the first thickening groove 1004 of the first adjusting plate 1001, so that the first adjusting plate 1001 can generate angular displacement relative to the third adjusting plate 1003 in a first direction. Preferably, the first direction may refer to... Figure 5 The horizontal direction is shown.

[0148] The second adjusting plate 1002 may have a second thickening groove 1005 at a position corresponding to the second surface 1003b of the third adjusting plate 1003. The second surface 1003b of the third adjusting plate 1003 may be connected to the second thickening groove 1005 of the second adjusting plate 1002, so that the second adjusting plate 1002 can generate angular displacement relative to the third adjusting plate 1003 in a second direction. Preferably, the second direction may refer to... Figure 5 The pitch direction is shown.

[0149] The first region of the third surface 1003c of the third adjusting plate 1003 may be provided with a first inclined surface 1006 that is inclined toward the first adjusting plate 1001. The second region of the third surface 1003c of the third adjusting plate 1003 may be provided with a second inclined surface 1007 that is inclined toward the second adjusting plate 1002. The third region of the third surface 1003c of the third adjusting plate 1003 may be provided with a threaded hole H for mounting the bracket 1008. Preferably, the first region of the third surface 1003c of the third adjusting plate 1003 may be as follows: Figure 7 The lower part of the third surface 1003c shown can have a second region as follows: Figure 7 The upper part of the third surface 1003c shown can be the third region as follows: Figure 7 The third surface 1003c shown is located in the middle. However, the invention is not limited to this; the first region, the second region, and the third region can be any position on the third surface 1003c.

[0150] The mounting bracket 1008 can be fitted with a first adjusting bolt 1009 at a position corresponding to the first inclined surface 1006 of the third adjusting plate 1003. The mounting bracket 1008 can be fitted with a second adjusting bolt 1010 at a position corresponding to the second inclined surface 1007 of the third adjusting plate 1003. The mounting bracket 1008 can be fitted with a fixing bolt at a position corresponding to the threaded hole H in the third region of the third surface 1003c of the third adjusting plate 1003, so as to fix the mounting bracket 1008 to the third adjusting plate 1003.

[0151] A first adjusting bead 1011 can be provided between the first adjusting bolt 1009 and the first inclined surface 1006 of the third adjusting plate 1003. A second adjusting bead 1012 can be provided between the second adjusting bolt 1010 and the second inclined surface 1007 of the third adjusting plate 1003.

[0152] To achieve surface contact between the first adjusting bead 1011 and the first inclined surface 1006 of the third adjusting plate 1003, the first adjusting bead 1011 can be cut to form a cutting plane, and the formed cutting plane contacts the first inclined surface 1006 of the third adjusting plate 1003. To achieve surface contact between the first adjusting bead 1011 and the first adjusting bolt 1009, the end of the first adjusting bolt 1009 that contacts the first adjusting bead 1011 can be set as a curved surface, and the radius of curvature of the curved surface is equal to the radius of the first adjusting bead 1011.

[0153] Similarly, to achieve surface contact between the second adjusting bead 1012 and the second inclined surface 1007 of the third adjusting plate 1003, the second adjusting bead 1012 can be cut to form a cutting plane, and the formed cutting plane contacts the second inclined surface 1007 of the third adjusting plate 1003. To achieve surface contact between the second adjusting bead 1012 and the second adjusting bolt 1010, the end of the second adjusting bolt 1010 that contacts the second adjusting bead 1012 can be set as a curved surface, and the radius of curvature of the curved surface is equal to the radius of the second adjusting bead 1012.

[0154] In addition, the first adjusting plate 1001 may be provided with a first slide rail 1013 at the position corresponding to the first adjusting bead 1011, so that the first adjusting bead 1011 can slide along the first slide rail 1013 when pushing the first adjusting plate 1001.

[0155] The second adjusting plate 1002 may be provided with a second slide rail 1014 at the position corresponding to the second adjusting bead 1012, so that the second adjusting bead 1012 can slide along the second slide rail 1014 when pushing the second adjusting plate 1002.

[0156] When adjusting the deflection angle of the first differential interference prism and / or the second differential interference prism via the angle adjustment mechanism 1000, the first adjusting bolt 1009 can be rotated in the first rotation direction, thereby displacing the first adjusting bolt 1009 towards the first adjusting bead 1011 to press the first adjusting bead 1011. Correspondingly, the first adjusting bead 1011 can slide along the first slide rail 1013 while displacing along the first inclined plane 1006, thereby pushing the first adjusting plate 1001 connected to the third adjusting plate 1003. As a result, the first adjusting plate 1001 can deflect relative to the third adjusting plate 1003 in the first direction, generating angular displacement. Since the first adjusting plate 1001 is fixedly connected to the housing of the wafer inspection system and cannot deflect, the third adjusting plate 1003 can deflect relative to the first adjusting plate 1001 in the first direction, generating angular displacement.

[0157] Conversely, when the first adjusting bolt 1009 is rotated in the second rotation direction (which is opposite to the first rotation direction), the direction in which the third adjusting plate 1003 deflects relative to the first adjusting plate 1001 in the first direction is opposite to the direction in which the third adjusting plate 1003 deflects relative to the first adjusting plate 1001 in the first direction when the first adjusting bolt 1009 is rotated in the first rotation direction.

[0158] Therefore, by rotating the first adjusting bolt 1009, the first or second differential interference prism, which is engaged with the second adjusting plate 1002, can be adjusted in the first direction (e.g., Figure 5 The deflection occurs in the horizontal direction shown.

[0159] Simultaneously, the second adjusting bolt 1010 can be rotated in the first rotational direction, thereby displacing the second adjusting bolt 1010 towards the second adjusting bead 1012 to press the second adjusting bead 1012. Correspondingly, the second adjusting bead 1012 can slide along the second slide rail 1014 while displacing along the second inclined plane 1007, thereby pushing the second adjusting plate 1002 connected to the third adjusting plate 1003. As a result, the second adjusting plate 1002 can deflect relative to the third adjusting plate 1003 in the second direction, generating angular displacement.

[0160] Conversely, when the second adjusting bolt 1010 is rotated in the second rotation direction (which is opposite to the first rotation direction), the direction in which the second adjusting plate 1002 deflects relative to the third adjusting plate 1003 in the second direction is opposite to the direction in which the second adjusting plate 1002 deflects relative to the third adjusting plate 1003 in the second direction when the second adjusting bolt 1010 is rotated in the first rotation direction.

[0161] Therefore, by rotating the second adjusting bolt 1010, the first differential interference prism or the second differential interference prism, which is engaged with the second adjusting plate 1002, can be adjusted in the second direction (e.g., Figure 5 The pitch direction shown indicates a deflection.

[0162] Here, when the first rotation direction is clockwise, the second rotation direction is counterclockwise, and vice versa.

[0163] Therefore, the deflection angles of the first differential interference prism 303 and the second differential interference prism 602 can be adjusted using the angle adjustment mechanism 1000 configured as described above. As a result, the angle between the two laser beams emitted from the first differential interference prism 303 can be precisely controlled, and by adjusting the second differential interference prism 602 in accordance with the first differential interference prism 303, precise beam combining of the two beams can be achieved. By precisely controlling the angle between the two beams emitted from the first differential interference prism 303, the beam separation angle with the best interference effect can be obtained, thereby improving the detection accuracy of bumps and depressions in wafers.

[0164] Figure 8 A flowchart illustrating a wafer inspection method according to an exemplary embodiment of the present invention is provided. Figure 1 The wafer inspection system shown in the exemplary embodiment of the present invention performs steps S101 to S105 of the following wafer inspection method.

[0165] like Figure 8 As shown, in step S101, the wafer to be tested can be placed on the sample stage 100.

[0166] In step S102, the controller 800 can control the first light source 201 of the light source system 200 to emit linearly polarized laser light of a first wavelength. The first light source 201 can emit laser light of a shorter wavelength that is beneficial for scattered light detection and will not cause photoluminescence defects on the wafer to emit photoluminescence. Preferably, the first wavelength can be 405 nm.

[0167] A linearly polarized laser of a first wavelength emitted from the first light source 201 can illuminate the wafer at a first predetermined angle via the first incident section 300 and be reflected by the wafer. The reflected light can then be incident on the coherent light detection section 600. Using the beam splitter 701 of the autofocus section 700, located between the analyzer 604 and lens 605 of the coherent light detection section 600, the light incident on the coherent light detection section 600 can be split into two beams. One beam can be incident on the position-sensitive detector 703 of the autofocus section 700. The position-sensitive detector 703 can convert the received optical signal into an electrical signal and send the converted electrical signal to the controller 800. The controller 800 can adjust the position of the housing based on the received electrical signal to focus on the surface of the wafer to be inspected. Thus, automatic focusing of the wafer can be achieved.

[0168] In step S103, the controller 800 can control the second light source 202 of the light source system 200 to emit a laser of a second wavelength. The second light source 202 can emit a short-wavelength laser capable of causing photoluminescence defects on the wafer to emit photoluminescence. Preferably, the second wavelength can be 355 nm.

[0169] In step S104, the controller 800 can control the sample stage 100 to rotate in a predetermined pattern, and at the same time, the controller 800 can control the housing to translate in a predetermined pattern. Thus, the spiral scanning of the wafer is achieved through the cooperation of the rotation of the sample stage 100 and the translation of the housing.

[0170] Specifically, the drive motor of the sample stage 100 can provide a rotary encoder position signal to the controller 800, and the drive motor of the housing can provide a linear motion grating ruler signal to the controller 800. Therefore, based on the feedback signals from the encoder and the grating ruler, the controller 800 can determine the wafer inspection position.

[0171] During the spiral scanning of the wafer, the controller 800 can control the detectors included in the coherent photodetector 500 and the incoherent photodetector 600 to detect the wafer.

[0172] Specifically, a linearly polarized laser of a first wavelength emitted from the first light source 201 can irradiate the wafer at a first predetermined angle via the first incident section 300.

[0173] The light of the first wavelength scattered by the scattering defects on the surface to be inspected of the wafer can be received by the fourth incoherent light detection unit 540 of the incoherent light detection unit 500. The fourth photomultiplier tube detector 544 of the fourth incoherent light detection unit 540 can detect the received scattered light signal. The fourth photomultiplier tube detector 544 can convert the received scattered light signal into a fourth electrical signal and send the converted fourth electrical signal to the controller 800.

[0174] Furthermore, light reflected by protrusions or depressions on the surface of the wafer to be inspected can be received by the coherent light detection unit 600 and interfered in the second differential interference prism 602 of the coherent light detection unit 600. The differential interference detector 606 of the coherent light detection unit 600 can detect the interference light signal. The differential interference detector 606 can convert the interference light signal into a fifth electrical signal and send the converted fifth electrical signal to the controller 800.

[0175] At the same time, a second wavelength laser emitted from the second light source 202 can irradiate the wafer at a second predetermined angle via the second incident section 400.

[0176] The photoluminescence emitted from a first photoluminescence defect on the surface of the wafer under test, within a first wavelength range, can be received by the first incoherent photodetector 510 of the incoherent photodetector 500. The first photomultiplier tube detector 514 of the first incoherent photodetector 510 can detect the received photoluminescence signal within the first wavelength range. The first photomultiplier tube detector 514 can convert the received photoluminescence signal within the first wavelength range into a first electrical signal and send the converted first electrical signal to the controller 800.

[0177] Furthermore, the second wavelength of light scattered by the scattering defects on the surface to be inspected of the wafer can be received by the second incoherent light detection unit 520 of the incoherent light detection unit 500. The second photomultiplier tube detector 524 of the second incoherent light detection unit 520 can detect the received scattered light signal. The second photomultiplier tube detector 524 can convert the received scattered light signal into a second electrical signal and send the converted second electrical signal to the controller 800.

[0178] Furthermore, the photoluminescence emitted from the second photoluminescence defect on the surface to be inspected of the wafer in the second wavelength range can be received by the third incoherent photodetector 530 of the incoherent photodetector 500. The third photomultiplier tube detector 534 of the third incoherent photodetector 530 can detect the received photoluminescence signal in the second wavelength range. The third photomultiplier tube detector 534 can convert the received photoluminescence signal in the second wavelength range into a third electrical signal and send the converted third electrical signal to the controller 800.

[0179] In one exemplary embodiment, in step S105, using an image processing algorithm, the controller 800 can determine the defects present in the wafer based on one of the received first electrical signal, second electrical signal, third electrical signal, fourth electrical signal, and fifth electrical signal.

[0180] Specifically, the controller 800 can detect a first photoluminescence defect based on a first electrical signal, a scattering defect based on a second or fourth electrical signal, a second photoluminescence defect based on a third electrical signal, and a protrusion and depression defect based on a fifth electrical signal.

[0181] In another exemplary embodiment, in step S105, using an image processing algorithm, the controller 800 can determine defects present in the wafer based on a combination of two or more of the received first, second, third, fourth, and fifth electrical signals. As an example, the controller 800 can detect scattering defects based on a combination of the second and fourth electrical signals. Furthermore, the controller 800 can detect stacking faults in a first photoluminescence defect based on a combination of the first and second electrical signals.

[0182] Furthermore, the controller 800 can match the detection position signal received from the sample stage 100 and the housing with the defect detection signal received from the coherent optical detection unit 500 and the incoherent optical detection unit 600, thereby determining the location of the detected wafer defect on the wafer.

[0183] After the first position of the wafer is detected, the detection position can be changed by rotating the sample stage 100 and translating the housing to detect the second position of the wafer. Step S105 can be repeated until all positions of the wafer are detected.

[0184] The wafer inspection method according to an exemplary embodiment of the present invention can detect photoluminescence defects, scattering defects, and protrusions and depressions on a wafer through a single inspection of a detection location. Furthermore, the wafer inspection method according to an exemplary embodiment of the present invention can distinguish between protrusions and depressions with dimensions as low as micrometers or even nanometers in the wafer, significantly improving the resolution of small-sized (e.g., below 5 micrometers) protrusions and depressions. Moreover, the wafer inspection system and method according to an exemplary embodiment of the present invention can improve the detection accuracy of wafer defects by utilizing the combination of signals output from various detectors.

[0185] The foregoing description of specific exemplary embodiments of the invention is for illustrative and descriptive purposes. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and it will be apparent that many modifications and variations can be made in light of the foregoing teachings. The exemplary embodiments were chosen and described to explain certain principles of the invention and its practical application, thereby enabling others skilled in the art to implement and utilize various exemplary embodiments of the invention, as well as their different alternatives and modifications. The scope of the invention is intended to be defined by the appended claims and their equivalents.

Claims

1. A wafer inspection system, comprising: Sample stage, used to place wafers; A light source system includes a first light source that emits a laser of a first wavelength and a second light source that emits a laser of a second wavelength, wherein the second wavelength is shorter than the first wavelength and is capable of causing photoluminescence defects in the wafer to produce photoluminescence. A first incident section, which is arranged downstream of the light source system and includes: A first differential interference prism is arranged between a first light source and a wafer to split the laser emitted from the first light source into two laser beams with an angle between them in space to irradiate the wafer. An incoherent optical detector, disposed downstream of the first incident portion in the optical path, includes: The objective lens, positioned above the wafer, is used to receive light scattered by scattering defects on the wafer and photoluminescence generated by photoluminescence defects on the wafer. The first incoherent photodetector is arranged downstream of the objective lens in the optical path to detect a first optical signal in a first wavelength range emitted from the second light source and generated by a first photoluminescence defect in the wafer, and outputs a first electrical signal. The second incoherent photodetector is arranged downstream of the first incoherent photodetector in the optical path. It is used to detect a second optical signal of a second wavelength emitted from the second light source and scattered by the scattering defects of the wafer, and to output a second electrical signal. A third incoherent photodetector, disposed downstream of the second incoherent photodetector, is used to detect a third optical signal within a second wavelength range emitted from the second light source and generated by a second photoluminescence defect in the wafer, and outputs a third electrical signal; and The fourth incoherent optical detector is arranged downstream of the third incoherent optical detector in the optical path. It is used to detect a fourth optical signal of a first wavelength emitted from the first light source and scattered by the scattering defects of the wafer, and to output a fourth electrical signal. A coherent light detector, disposed downstream of the first incident portion in the optical path, includes: The second differential interference prism, positioned symmetrically to the first differential interference prism relative to the wafer, is used to spatially combine the two laser beams emitted from the first differential interference prism and reflected from the wafer into a single laser beam, enabling interference between the two beams. A differential interferometer detector, positioned downstream of the second differential interferometer prism, is used to detect interference light signals reflected and interfered by bulges and / or depressions in the wafer, and outputs a fifth electrical signal; and A controller configured to receive a first electrical signal, a second electrical signal, a third electrical signal, a fourth electrical signal, and a fifth electrical signal, and to determine a defect present in the wafer based on at least one or a combination of the first electrical signal, the second electrical signal, the third electrical signal, the fourth electrical signal, and the fifth electrical signal; In this process, a laser of a first wavelength emitted from a first light source passes through a first incident section and is obliquely incident on the wafer at a first predetermined angle.

2. The wafer inspection system according to claim 1, wherein, The first incident portion further includes: A half-wave plate, positioned between the first light source and the first differential interference prism, is used to adjust the polarization direction of a first wavelength laser emitted from the first light source so that it matches the optical axis of the first differential interference prism; and A first lens is positioned between a first differential interference prism and the wafer to convert two laser beams with an included angle into two parallel laser beams and focus them onto the wafer.

3. The wafer inspection system according to claim 2, wherein, The coherent optical detector further includes: A second lens, positioned symmetrically to the first lens relative to the wafer, collimates the two parallel diverging laser beams emitted from the first light source and reflected by the wafer; and The analyzer is arranged between the second differential interference prism and the differential interference detector. By adjusting the analyzer, the contrast of the interference light signal of the laser emitted from the second differential interference prism is maximized.

4. The wafer inspection system according to claim 3, further comprising a second incident section, the second incident section comprising: At least one reflector is arranged between the second light source and the wafer to illuminate the wafer at a second predetermined angle with a laser of a second wavelength emitted from the second light source. and A third lens is positioned between the second light source and the wafer to focus a second wavelength laser emitted from the second light source onto the wafer.

5. The wafer inspection system according to claim 4, wherein, The incoherent optical detector further includes: An aperture, which is arranged between the objective lens and the first incoherent light detector, is used to receive light emitted from the objective lens and filter stray light; The first incoherent optical detector includes: The first dichroic mirror is arranged downstream of the aperture in the optical path to reflect light with wavelengths less than or equal to the first wavelength and transmit light with wavelengths greater than the first wavelength in the light filtered by the aperture. The first pinhole, which is arranged downstream of the first dichroic mirror, is used to receive light transmitted through the first dichroic mirror and filter stray light. A first filter, disposed downstream of the first pinhole in the optical path, is used to filter out light of a first wavelength range from the light received through the first pinhole; and A first photomultiplier tube detector is arranged downstream of the first filter in the optical path to detect a first optical signal in a first wavelength range filtered by the first filter and to output a first electrical signal.

6. The wafer inspection system according to claim 5, wherein, The second incoherent optical detector includes: The second dichroic mirror is arranged downstream of the first dichroic mirror in the optical path. It is used to reflect light with a wavelength shorter than the third wavelength and transmit light with a wavelength greater than or equal to the third wavelength after the light is reflected by the first dichroic mirror. The third wavelength is shorter than the first wavelength and longer than the second wavelength. The second pinhole, which is arranged downstream of the second dichroic mirror, is used to receive the light reflected by the second dichroic mirror and filter stray light. A second filter, positioned downstream of the second pinhole in the optical path, is used to filter out light of a second wavelength from the light received through the second pinhole; and The second photomultiplier tube detector is arranged downstream of the optical path relative to the second filter. It is used to detect the second optical signal of the second wavelength filtered by the second filter and output the second electrical signal.

7. The wafer inspection system according to claim 6, wherein, The third incoherent optical detector includes: A third dichroic mirror is arranged downstream of the second dichroic mirror in the optical path. It is used to reflect light with a wavelength less than the fourth wavelength after it is reflected by the second dichroic mirror and transmit light with a wavelength greater than or equal to the fourth wavelength, wherein the fourth wavelength is shorter than the first wavelength and longer than the third wavelength. The third pinhole, which is arranged downstream of the third dichroic mirror, is used to receive light reflected by the third dichroic mirror and filter stray light. A third filter, positioned downstream of the third pinhole in the optical path, is used to filter out light in the second wavelength range from the light received through the third pinhole; and The third photomultiplier tube detector is positioned downstream of the optical path relative to the third filter. It is used to detect the third optical signal in the second wavelength range filtered by the third filter and to output the third electrical signal.

8. The wafer inspection system according to claim 7, wherein, The fourth incoherent optical detector includes: The fourth pinhole, which is arranged downstream of the third dichroic mirror, is used to receive light transmitted through the third dichroic mirror and filter stray light. A fourth filter, positioned downstream of the fourth pinhole in the optical path, is used to filter out light of the first wavelength from the light received through the fourth pinhole; and The fourth photomultiplier tube detector is positioned downstream of the optical path relative to the fourth filter. It is used to detect the fourth optical signal of the first wavelength filtered by the fourth filter and output the fourth electrical signal.

9. The wafer inspection system according to claim 8, wherein, The first predetermined angle is in the range of 45° to 80°, and the second predetermined angle is in the range of 2° to 5°.

10. The wafer inspection system according to claim 1, further comprising: An angle adjustment mechanism is provided on the first differential interference prism and the second differential interference prism to change the deflection angle of the first differential interference prism and the second differential interference prism; The angle adjustment mechanism includes: The first adjustment plate is fixedly connected to the housing of the wafer inspection system so that it will not undergo angular displacement relative to the optical path during adjustment; A second adjustment plate, used to mount either the first or second differential interference prism; and A third adjusting plate is disposed between the first adjusting plate and the second adjusting plate. The third adjusting plate is connected to the first adjusting plate by a relative angular displacement on one side and to the second adjusting plate by a relative angular displacement on the other side.

11. The wafer inspection system according to claim 10, wherein, The third adjusting plate has a first surface, a second surface, a third surface, and a fourth surface connected in sequence; The first adjusting plate is provided with a first thickening groove at a position corresponding to the first surface, and the first surface of the third adjusting plate is connected to the first thickening groove so that the first adjusting plate can generate angular displacement relative to the third adjusting plate in a first direction. The second adjusting plate is provided with a second thickening groove at a position corresponding to the second surface, and the second surface of the third adjusting plate is connected to the second thickening groove so that the second adjusting plate can generate angular displacement relative to the third adjusting plate in the second direction. The third surface of the third adjusting plate has a first inclined surface inclined toward the first adjusting plate in the first region, and the third surface of the third adjusting plate has a second inclined surface inclined toward the second adjusting plate in the second region. The third surface of the third adjusting plate is fixedly connected to a mounting bracket. The mounting bracket is equipped with a first adjusting bolt corresponding to the position of the first inclined surface, and the mounting bracket is equipped with a second adjusting bolt corresponding to the position of the second inclined surface. A first adjusting bead is provided between the first adjusting bolt and the first inclined surface, and a second adjusting bead is provided between the second adjusting bolt and the second inclined surface. By rotating the first adjusting bolt in the first rotation direction, the first adjusting bolt is displaced toward the first adjusting bead to squeeze the first adjusting bead, so that the first adjusting bead is displaced along the first inclined plane to push the first adjusting plate to produce an angular displacement relative to the third adjusting plate in the first direction; By rotating the second adjusting bolt in the first rotation direction, the second adjusting bolt is displaced toward the second adjusting bead to squeeze the second adjusting bead, causing the second adjusting bead to displace along the second inclined plane to push the second adjusting plate to produce an angular displacement relative to the third adjusting plate in the second direction.

12. The wafer inspection system according to claim 11, wherein, The portion of the first adjusting bead that contacts the first inclined surface is configured as a cutting plane to achieve surface contact between the first adjusting bead and the first inclined surface; The first adjusting plate is provided with a first slide rail at a position corresponding to the first adjusting bead, so that the first adjusting bead can slide along the first slide rail when pushing the first adjusting plate; the end of the first adjusting bolt that contacts the first adjusting bead is provided with a concave surface; The second adjusting bead has a cutting plane at the part that contacts the second inclined surface to achieve surface contact between the second adjusting bead and the second inclined surface; the second adjusting plate has a second slide rail at the position corresponding to the second adjusting bead so that the second adjusting bead can slide along the second slide rail when pushing the second adjusting plate; the end of the second adjusting bolt that contacts the second adjusting bead has a concave surface.

13. A method for wafer inspection using the wafer inspection system according to any one of claims 1-12, comprising: Place the wafer on the sample stage; Irradiating the wafer using a light source system; The wafer is automatically focused using an autofocus system; The sample stage and the housing of the wafer inspection system are controlled to move in a predetermined pattern, thereby performing a spiral scan on the wafer. Control the coherent and incoherent photodetectors to inspect the wafer; Among them, incoherent optical detection units are used to detect scattering defects and photoluminescence defects in wafers; Coherent optical detectors are used to detect bumps and depressions in wafers.

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