Apparatus for wafer surface warpage detection

Abstract

The application provides a device for wafer surface warping detection, comprising a first detection light path, a second detection light path and a third detection light path, the first detection light path is used for irradiating a first grating texture of a first target right field region to generate first diffraction light along a Y direction, the second detection light path is used for irradiating a second grating texture of a second target left field region to generate second diffraction light along an X direction; the third detection light path respectively irradiates a third grating texture arranged in a right field region of a third target and a fourth grating texture of a left field region to generate third diffraction light along the Y direction and fourth diffraction light along the X direction; the first diffraction light and the third diffraction light are superimposed to form first moire fringes, which can be used for measuring wafer Y direction warping, and the second diffraction light and the fourth diffraction light are superimposed to form second moire fringes, which can be used for measuring wafer X direction warping. The application can avoid dynamic errors introduced by scanning motion and cumulative errors of splicing, and improve the precision of wafer warping detection.

Description

Technical Field

[0001] This application relates to the field of semiconductor defect detection, and more particularly to an apparatus for detecting wafer surface warping. Background Technology

[0002] In semiconductor manufacturing and advanced packaging, wafer warpage refers to the global or local out-of-plane deformation of a wafer caused by thin-film stress, thermal cycling, and material thermodynamic mismatch. It is typically quantified by the PV values ​​of bow and global warpage. Bow is defined as the deviation of the center point of the mid-plane from a reference plane determined by three equidistant points on the edge in a free, unconstrained state. Global warpage is defined as the difference between the maximum and minimum distances of all points on the mid-plane from this reference plane, characterizing the extreme range of deviations from the ideal plane. Because the intrinsic stress of the multilayer films on the wafer and the mismatch in the coefficients of thermal expansion between materials are locked into the structure during thermal cycling, exhibiting a composite curvature of global bending or even a saddle shape, wafer warpage can only be suppressed through symmetrical stacking, stress engineering, material selection, thickness control, and thermal budgeting, but cannot be completely eliminated. The hazards of wafer warpage permeate critical processes in semiconductor manufacturing: In photolithography, due to the extremely shallow depth of focus, warpage causes local defocusing, leading to deviations in critical gate dimensions and affecting alignment errors between different layers; in CMP, uneven contact pressure distribution causes uneven removal rates, worsening thickness and stress distribution; in bonding and advanced packaging, wafer warpage creates non-uniform gaps, inducing defects such as voids, weak bonding, incomplete wetting, and die drift.

[0003] To detect wafer warpage, commonly used methods include interferometry, capacitive eddy current array (CFD) methods, spectral confocal methods, and laser triangulation. While interferometry can achieve nanometer-level vertical resolution, it is extremely sensitive to environmental vibrations and air disturbances, difficult to adapt to large-area, high-curvature samples, and its mechanical scanning approach is unsuitable for production line cycles. Although CFD can quickly extract Bow / Warp values ​​in mass production, it relies on the conductive back side of the sample, is sensitive to oxide layers / contamination, and the support conditions themselves can alter wafer boundary conditions, introducing additional deformation. The output is a sparse point cloud, lacking continuous full-field topographic information. Spectroscopic confocal methods offer nanometer-level vertical resolution and have some adaptability to mirror surfaces, but their essence is point-by-point or line-by-line scanning measurement. Large-area wafers require high-density sampling and multi-field stitching, which introduces mechanical motion errors, temperature drift, and cumulative stitching errors. Laser triangulation is widely used due to its simple structure and fast response. However, it suffers from high sensitivity to surface reflectivity and roughness. Mirror silicon areas, metal wiring areas, or dielectric films on the wafer surface can easily cause saturation of the receiving spot, multipath reflection, and misreading of film interfaces. Furthermore, when the slope angle caused by local surface warping is too large, laser triangulation can result in shadowing, making measurements of the edges and transition regions of the entire warped field unstable. In addition, point-by-point scanning introduces mechanical dynamic errors, creating a bottleneck in sub-100-nanometer warping detection. Therefore, there is an urgent need for a non-contact measurement scheme that can perform high-sensitivity measurement of the entire wafer warping surface with low sensitivity to surface optical properties without requiring high-density point-by-point scanning. Summary of the Invention

[0004] This application provides an apparatus for detecting wafer surface warpage, which avoids dynamic errors and splicing accumulation errors introduced by scanning motion, thereby improving the accuracy of wafer warpage detection.

[0005] An apparatus for detecting wafer surface warpage, comprising:

[0006] A first detection optical path is provided in the first detection optical path, and a first target is provided in the right field of view area of ​​the first target along the X direction. The first detection optical path is used to illuminate the first grating texture to generate first diffraction light along the Y direction.

[0007] A second detection optical path is provided in the second detection optical path, and a second target is provided in the left field of view of the second target. A second grating texture along the Y direction is provided, and the Y direction is perpendicular to the X direction. The second detection optical path is used to illuminate the second grating texture to generate a second diffracted light along the X direction.

[0008] The third detection optical path includes a third target. The right field of view of the third target is provided with a third grating texture along the X direction, and the left field of view of the third target is provided with a fourth grating texture along the Y direction. The third detection optical path is used to illuminate the third grating texture and the fourth grating texture respectively to generate third diffraction light along the Y direction and fourth diffraction light along the X direction.

[0009] The first diffracted light and the third diffracted light superimpose to form a first moiré fringe, and the second diffracted light and the fourth diffracted light superimpose to form a second moiré fringe.

[0010] In one possible implementation, the fringe period P of the first moiré fringe is... M1 The following relationship must be satisfied:

[0011] ;

[0012] Wherein, P1 is the grating period of the first grating texture, and P3 is the grating period of the third grating texture.

[0013] In one possible implementation, the fringe period P of the second moiré fringe M2 The following relationship must be satisfied:

[0014] ;

[0015] Wherein, P2 is the grating period of the second grating texture, and P4 is the grating period of the fourth grating texture.

[0016] In one possible implementation, the first detection optical path includes:

[0017] The laser source, laser mirror group, integrating bar, collimating lens group, polarizer, first beam splitter, first quarter-wave plate, and second beam splitter are arranged sequentially along the optical path.

[0018] A second quarter-wave plate, a first aperture, a first focusing imaging lens group, and a first target are sequentially arranged along the reflected light path of the second beam splitter.

[0019] The optical path compensation plate, the first half-wave plate, the third beam splitter, the third aperture, the fourth quarter-wave plate, the refraction mirror group, the first imaging plane, the catadioptric mirror group, and the second imaging plane are arranged sequentially in the opposite direction to the reflected light path of the second beam splitter.

[0020] The second half-wave plate, the fourth beam splitter, the fifth aperture, the fourth focusing imaging mirror group, the third imaging image plane, the microscopic imaging mirror group, and the detector image plane are arranged sequentially along the reflected light path of the third beam splitter.

[0021] In one possible implementation, the first aperture is provided with a first light-transmitting hole, a second light-transmitting hole and a third light-transmitting hole, the third light-transmitting hole is located at the center of the first aperture, the second light-transmitting hole and the first light-transmitting hole are symmetrically arranged along the Y direction and are respectively aligned with the +1st order diffraction light and the -1st order diffraction light generated by the first grating texture.

[0022] In one possible implementation, the second detection optical path includes:

[0023] The laser source, laser mirror group, integrating bar, collimating lens group, polarizer, first beam splitter, first quarter-wave plate, and second beam splitter are arranged sequentially along the optical path.

[0024] A third quarter-wave plate, a second aperture, a second focusing imaging lens group, and a second target are sequentially arranged along the transmission optical path of the second beam splitter.

[0025] The optical path compensation plate, the first half-wave plate, the third beam splitter, the third aperture, the fourth quarter-wave plate, the refraction mirror group, the first imaging plane, the catadioptric mirror group, and the second imaging plane are arranged sequentially in the opposite direction to the reflected light path of the second beam splitter.

[0026] The second half-wave plate, the fourth beam splitter, the fifth aperture, the fourth focusing imaging mirror group, the fourth imaging image plane, the microscopic imaging mirror group, and the detector image plane are arranged sequentially along the reflected light path of the third beam splitter.

[0027] In one possible implementation, the second aperture is provided with a fourth light-transmitting hole, a fifth light-transmitting hole and a sixth light-transmitting hole. The sixth light-transmitting hole is located at the center of the second aperture. The fifth light-transmitting hole and the fourth light-transmitting hole are symmetrically arranged along the X direction and are respectively aligned with the +1st order diffraction light and the -1st order diffraction light generated by the second grating texture.

[0028] In one possible implementation, the third detection optical path includes:

[0029] The laser source, laser mirror group, integrating bar, collimating lens group, polarizer, and first beam splitter are arranged sequentially along the optical path.

[0030] The third half-wave plate, the fourth beam splitter, the fifth quarter-wave plate, the fourth aperture, the third focusing imaging lens group, and the third target are arranged sequentially along the reflected light path of the first beam splitter.

[0031] The fifth aperture, the fourth focusing imaging lens group, the fifth imaging image plane, the microscopic imaging lens group, and the detector image plane are arranged sequentially along the reflected light path of the fourth beam splitter.

[0032] In one possible implementation, the surface of the fourth aperture is provided with a light-absorbing material, and the fourth aperture is provided with an eleventh, twelfth, thirteenth, fourteenth, and fifteenth light-transmitting hole. The twelfth and eleventh light-transmitting holes are symmetrically distributed along the Y direction and are aligned with the +1st and -1st order diffracted light generated by the third grating texture, respectively. The fourteenth and thirteenth light-transmitting holes are symmetrically distributed along the X direction and are aligned with the +1st and -1st order diffracted light generated by the fourth grating texture, respectively. The fifteenth light-transmitting hole is located at the center of the fourth aperture.

[0033] In one possible implementation, the surface of the third aperture is provided with a light-absorbing material, and the third aperture is provided with a seventh, eighth, ninth, and tenth light-transmitting hole. The seventh and eighth light-transmitting holes are symmetrically arranged along the Y direction and are aligned with the -1st and +1st order diffraction light generated by the first grating texture, respectively. The ninth and tenth light-transmitting holes are symmetrically arranged along the X direction and are aligned with the -1st and +1st order diffraction light generated by the second grating texture, respectively.

[0034] In one possible implementation, the surface of the optical path compensation sheet is coated with an antireflection film, and the optical path compensation sheet is provided with a first hollow area and a second hollow area, and the first hollow area and the second hollow area are respectively aligned with the +1st order diffraction light and the -1st order diffraction light generated by the second grating texture.

[0035] In one possible implementation, an antireflection film is deposited on the first half-wave plate, and a third and a fourth hollowed-out region are provided on the first half-wave plate, with the third and fourth hollowed-out regions respectively aligned with the +1st and -1st order diffraction light generated by the first grating texture.

[0036] In one possible implementation, the spatial angle between the fast axis of the first half-wave plate and the transmission axis of the P-light transmitted by the second beam splitter is 45 degrees.

[0037] In one possible implementation, the third beam splitter is a polarizing beam splitter, and the P-ray transmission axis of the third beam splitter coincides with the transmission P-ray transmission axis of the second beam splitter.

[0038] In one possible implementation, the spatial angle between the fast axis of the fourth quarter-wave plate and the transmission axis of the P-beam of the third beam splitter is 45 degrees.

[0039] In one possible implementation, the spatial angle between the fast axis of the second half-wave plate and the reflected S-ray transmission axis of the third beam splitter is 45 degrees.

[0040] In one possible implementation, the spatial angle between the fast axis of the third half-wave plate and the reflected S-ray transmission axis of the first beam splitter is 45 degrees.

[0041] In one possible implementation, the fifth aperture is provided with a sixteenth, seventeenth, eighteenth, and nineteenth light-transmitting aperture. The surface of the fifth aperture is coated with a light-absorbing material. The seventeenth and sixteenth light-transmitting apertures are symmetrically arranged along the Y direction and are aligned with the +1st and -1st order diffraction light generated by the third grating texture, respectively. The nineteenth and eighteenth light-transmitting apertures are symmetrically arranged along the X direction and are aligned with the +1st and -1st order diffraction light generated by the fourth grating texture, respectively.

[0042] In one possible implementation, the spatial angle between the transmission P-axis of the fourth beam splitter and the fast axis of the fifth quarter-wave plate is 45 degrees.

[0043] The apparatus for detecting wafer surface warpage provided in this application embodiment includes a first detection optical path that is incident on the right field of view of a first target in the normal direction. The right field of view of the first target is provided with a first grating texture along the X direction, generating first diffracted light along the Y direction. A second detection optical path is incident on the left field of view of a second target in the normal direction. The left field of view of the second target is provided with a second grating texture along the Y direction, generating second diffracted light along the X direction. A third detection optical path is incident on the left and right field of view of a third target in the normal direction. The right field of view of the third target is provided with a third grating texture along the X direction, and the left field of view of the third target is provided with a fourth grating texture along the Y direction, generating third diffracted light along the Y direction and fourth diffracted light along the X direction. The first and third diffracted beams are superimposed to form a first moiré fringe along the X-direction, which can be used to measure wafer warpage in the Y-direction. The second and fourth diffracted beams are superimposed to form a second moiré fringe along the Y-direction, which can be used to measure wafer warpage in the X-direction. This application utilizes grating diffraction to form moiré fringes, mapping the change in the wafer surface height field to an acquireable fringe phase field. The wafer warpage distribution is obtained through phase-shift demodulation, which can avoid dynamic errors and splicing accumulation errors introduced by scanning motion. It has higher robustness to changes in wafer surface reflectivity or film optical properties, and improves the accuracy of wafer warpage detection. Attached Figure Description

[0044] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0045] Figure 1 This is a schematic diagram of the diffraction of light from dual-polarized illumination.

[0046] Figure 2 This is a schematic diagram of the device for detecting wafer surface warpage provided in this application;

[0047] Figure 3 This is a schematic diagram of the first detection optical path provided in an embodiment of this application;

[0048] Figure 4 This is a schematic diagram of the second detection optical path provided in an embodiment of this application;

[0049] Figure 5 This is a schematic diagram of the third detection optical path provided in an embodiment of this application;

[0050] Figure 6 A schematic diagram of the structure of the first target provided in an embodiment of this application;

[0051] Figure 7 This is a schematic diagram of the structure of the second target provided in an embodiment of this application;

[0052] Figure 8 A schematic diagram of the structure of the third target provided in the embodiments of this application;

[0053] Figure 9 A schematic diagram of ±1st order diffraction of the grating texture in the right field of view of the first target;

[0054] Figure 10 A schematic diagram of ±1st order diffraction of the grating texture in the left field of view of the second target;

[0055] Figure 11 This is a schematic diagram of ±1st order diffraction of the grating texture in the left and right field-of-view regions of the third target;

[0056] Figure 12 This is a schematic diagram of the structure of the first aperture provided in an embodiment of this application;

[0057] Figure 13 This is a schematic diagram of the structure of the second aperture provided in an embodiment of this application;

[0058] Figure 14 This is a schematic diagram of the structure of the third aperture provided in an embodiment of this application;

[0059] Figure 15 This is a schematic diagram of the structure of the fourth aperture provided in an embodiment of this application;

[0060] Figure 16 This is a schematic diagram of the structure of the fifth aperture provided in an embodiment of this application;

[0061] Figure 17 This is a schematic diagram of the structure of the optical path compensation plate provided in the embodiments of this application;

[0062] Figure 18A schematic diagram of the structure of the first half-wave plate provided in the embodiments of this application;

[0063] Figure 19 A schematic diagram of the first moiré fringe provided for an embodiment of this application;

[0064] Figure 20 A schematic diagram of the second moiré fringe provided for an embodiment of this application;

[0065] Figure 21 A schematic diagram of total moiré fringes provided for embodiments of this application.

[0066] Figure label:

[0067] 1. Laser source; 2. Laser mirror assembly; 3. Integrating rod; 4. Collimating lens assembly; 5. Polarizer; 6. First beam splitter; 7. First quarter-wave plate; 8. Second beam splitter; 9. Second quarter-wave plate; 10. First focusing imaging lens assembly; 11. Third quarter-wave plate; 12. Second focusing imaging lens assembly; 13. Third half-wave plate; 14. Optical path compensation plate; 141. First cutout area; 142. Second cutout area; 15. First half-wave plate; 15 1. Third cutout area; 152. Fourth cutout area; 16. Third beam splitter prism; 17. Fourth quarter-wave plate; 18. Refracting mirror group; 19. Catadioptric mirror group; 20. Second half-wave plate; 21. Fourth beam splitter prism; 22. Fifth quarter-wave plate; 23. Third focusing imaging mirror group; 24. Fourth focusing imaging mirror group; 25. Microscopic imaging mirror group; 26. First aperture; 261. First light-transmitting aperture; 262. Second light-transmitting aperture; 263. Third light-transmitting aperture 27. Second aperture; 271. Fourth aperture; 272. Fifth aperture; 273. Sixth aperture; 28. Third aperture; 281. Seventh aperture; 282. Eighth aperture; 283. Ninth aperture; 284. Tenth aperture; 29. ​​Fourth aperture; 291. Eleventh aperture; 292. Twelfth aperture; 293. Thirteenth aperture; 294. Fourteenth aperture; 295. Fifteenth aperture; 30. Fifth aperture; 301. Sixteenth aperture Aperture; 302, Seventeenth light-transmitting aperture; 303, Eighteenth light-transmitting aperture; 304, Nineteenth light-transmitting aperture; 31, First imaging plane; 32, Second imaging plane; 33, Third imaging plane; 34, Fourth imaging plane; 35, Fifth imaging plane; 36, Detector plane; 100, First target; 110, First grating texture; 200, Second target; 210, Second grating texture; 300, Third target; 310, Third grating texture; 320, Fourth grating texture.

[0068] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0069] First, those skilled in the art should understand that these embodiments are merely for explaining the technical principles of this application and are not intended to limit the scope of protection of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0070] Secondly, it should be noted that, in the description of the embodiments of this application, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0071] In semiconductor manufacturing and advanced packaging, wafer warpage refers to the global or local out-of-plane deformation of a wafer caused by thin-film stress, thermal cycling, and material thermodynamic mismatch. It is usually quantified by the PV values ​​of bow and global warpage. The hazards of wafer warpage run through critical processes in semiconductor manufacturing: in photolithography, due to the extremely shallow depth of focus, warpage causes local defocusing, leading to deviations in critical gate dimensions and affecting alignment errors between different layers; in CMP, uneven contact pressure distribution causes uneven removal rates, worsening thickness and stress distribution; in bonding and advanced packaging, wafer warpage creates non-uniform gaps, inducing defects such as voids, weak bonding, incomplete wetting, and die drift.

[0072] To detect wafer warpage, commonly used methods include interferometry, capacitive eddy current array (CFD) methods, spectral confocal methods, and laser triangulation. While interferometry can achieve nanometer-level vertical resolution, it is extremely sensitive to environmental vibrations and air disturbances, difficult to adapt to large-area, high-curvature samples, and its mechanical scanning approach is unsuitable for production line cycles. Although CFD can quickly extract Bow / Warp values ​​in mass production, it relies on the conductive back side of the sample, is sensitive to oxide layers / contamination, and the support conditions themselves can alter wafer boundary conditions, introducing additional deformation. The output is a sparse point cloud, lacking continuous full-field topographic information. Spectroscopic confocal methods offer nanometer-level vertical resolution and have some adaptability to mirror surfaces, but their essence is point-by-point or line-by-line scanning measurement. Large-area wafers require high-density sampling and multi-field stitching, which introduces mechanical motion errors, temperature drift, and cumulative stitching errors. Laser triangulation is widely used due to its simple structure and fast response. However, it is highly sensitive to surface reflectivity and roughness. Mirror silicon areas, metal wiring areas, or dielectric films on the wafer surface can easily cause saturation of the receiving spot, multipath reflection, and misreading of the film interface. In addition, when the slope angle caused by local surface warping is too large, the laser triangulation method will cause shadowing, making the measurement of the edge and transition regions of the entire warped field unstable. Furthermore, point-by-point scanning introduces mechanical dynamic errors, making it a bottleneck in the detection of warping at the sub-100 nanometer level.

[0073] Moiré fringes are a common and highly characteristic spatial interference phenomenon in precision optical inspection. When two regular grating structures with similar spatial frequencies, such as two linear gratings with similar spatial periods, are superimposed in space in some way, such as physical superposition, projection superposition, imaging superposition, or diffraction superposition, macroscopic fringes with lower spatial frequencies will be observed at the Talbot height, resulting in a stable beat frequency signal, i.e., moiré fringes. When there is a tiny displacement or a tiny spatial angle between the two gratings, it will be directionally amplified in the beat frequency signal, causing a large phase shift in the moiré fringes. By processing this phase resolution algorithm, nanometer-scale deformation of the measured surface can be detected.

[0074] To address the aforementioned technical problems, this application provides an apparatus for detecting wafer surface warpage. It uses grating diffraction to superimpose moiré fringes, mapping changes in the wafer surface height field to an acquireable fringe phase field. Wafer warpage distribution is obtained through phase-shift demodulation, avoiding dynamic errors and splicing accumulation errors introduced by scanning motion. This provides higher robustness to changes in wafer surface reflectivity or film optical properties. Through the coordinated design of grating period, optical system resolution and magnification, and phase-shift demodulation, controllable amplification of warpage sensitivity is achieved, enabling nanoscale detection of wafer warpage.

[0075] To make the above-mentioned objectives, features, and advantages of the embodiments of this application more apparent and understandable, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0076] Please refer to Figures 1-21 This application provides an apparatus for detecting wafer surface warpage, comprising:

[0077] A first detection optical path is provided in which a first target 100 is provided. The right field of view of the first target 100 is provided with a first grating texture 110 along the X direction. The first detection optical path is used to illuminate the first grating texture 110 to generate first diffraction light along the Y direction.

[0078] The second detection optical path includes a second target 200. The left field of view of the second target 200 is provided with a second grating texture 210 along the Y direction, and the Y direction is perpendicular to the X direction. The second detection optical path is used to illuminate the second grating texture 210 to generate second diffraction light along the X direction.

[0079] The third detection optical path includes a third target 300. The right field of view of the third target 300 is provided with a third grating texture 310 along the X direction, and the left field of view of the third target 300 is provided with a fourth grating texture 320 along the Y direction. The third detection optical path is used to illuminate the third grating texture 310 and the fourth grating texture 320 respectively to generate third diffraction light along the Y direction and fourth diffraction light along the X direction.

[0080] The first diffracted light and the third diffracted light superimpose to form the first moiré fringe, and the second diffracted light and the fourth diffracted light superimpose to form the second moiré fringe.

[0081] This application transmits light through a first detection optical path to the right field of view of the first target 100 in the normal direction. The right field of view of the first target 100 is provided with a first grating texture 110 along the X direction (see reference). Figure 6 This will produce first-order diffraction light along the Y direction (including +1st-order and -1st-order diffraction light), forming Y-direction dual-polarized illumination (see...). Figure 9 The second detection optical path is incident on the left field of view of the second target 200 in the normal direction. The left field of view of the second target 200 is provided with a second grating texture 210 along the Y direction (see...). Figure 7 This generates a second diffracted beam along the X-direction (including the +1st and -1st order diffracted beams), forming dual-polarized illumination in the X-direction (see [reference]). Figure 10 (The third detection optical path is incident on the left and right fields of view of the third target 300 in the normal direction. See reference.) Figure 8 The right field of view of the third target 300 is provided with a third grating texture 310 along the X-direction, generating third diffraction light (including +1st order and -1st order diffraction light) along the Y-direction, forming dual-polarized illumination in the Y-direction. The left field of view of the third target 300 is provided with a fourth grating texture 320 along the Y-direction, generating fourth diffraction light (including +1st order and -1st order diffraction light) along the X-direction, forming dual-polarized illumination in the X-direction. During the detection process, the diffraction light of the first grating texture 110±1st order and the diffraction light of the third grating texture 310±1st order superimposed form moiré fringes along the X-direction, which can measure the warpage of the wafer in the Y-direction. The diffraction light of the second grating texture 210±1st order and the diffraction light of the fourth grating texture 320±1st order superimposed form moiré fringes along the Y-direction, which can measure the warpage of the wafer in the X-direction. This application utilizes grating diffraction superposition to form moiré fringes, mapping changes in the height field of the wafer surface into an acquireable fringe phase field. By performing phase calculation on the moiré fringes, nanometer-level deformation of the measured surface can be detected, obtaining the wafer warpage distribution. Moiré fringes can achieve physical magnification of over 1000 times; combined with sub-pixel algorithms, magnification capabilities of tens of thousands to hundreds of thousands of times can be achieved, achieving nanometer-level detection accuracy. Compared to the sub-hundred-nanometer accuracy of laser triangulation, the detection accuracy is significantly improved. This application uses grating diffraction superposition to form moiré fringes. Compared to interferometry, this application is less sensitive to environmental vibrations and air disturbances, can adapt to large-area, high-curvature samples, and can avoid dynamic errors and splicing accumulation errors introduced by scanning motion. It also has higher robustness to changes in wafer surface reflectivity or film optical properties, improving the accuracy of wafer warpage detection.

[0082] In some embodiments of this application, the fringe period P of the first moiré fringe M1 The following relationship must be satisfied:

[0083] ;

[0084] Wherein, P1 is the grating period of the first grating texture 110, and P3 is the grating period of the third grating texture 310.

[0085] Preferably, the first moiré fringe has at least three fringe periods.

[0086] In some embodiments of this application, the fringe period P of the second moiré fringe M2 The following relationship must be satisfied:

[0087] ;

[0088] Wherein, P2 is the raster period of the second raster texture 210, and P4 is the raster period of the fourth raster texture 320.

[0089] Preferably, the second moiré fringe has at least three fringe periods.

[0090] It is understandable that the raster period P1 of the first raster texture 110 and the raster period P2 of the second raster texture 210 can be the same or different. Similarly, the raster period P3 of the fourth raster texture 320 and the raster period P4 of the fourth raster texture 320 can be the same or different.

[0091] In some embodiments of this application, see Figure 3 The first detection optical path includes: a laser source 1, a laser mirror group 2, an integrating rod 3, a collimating lens group 4, a polarizer 5, a first beam splitter 6, a first quarter-wave plate 7, and a second beam splitter 8 arranged sequentially along the optical path direction; a second quarter-wave plate 9, a first aperture 26, a first focusing imaging lens group 10, and a first target 100 arranged sequentially along the reflected optical path of the second beam splitter 8; an optical path compensation plate 14, a first half-wave plate 15, a third beam splitter 16, a third aperture 28, a fourth quarter-wave plate 17, a refractor mirror group 18, a first imaging image plane 31, a catadioptric mirror group 19, and a second imaging image plane 32 arranged sequentially along the opposite direction of the reflected optical path of the second beam splitter 8; and a second half-wave plate 20, a fourth beam splitter 21, a fifth aperture 30, a fourth focusing imaging lens group 24, a third imaging image plane 33, a microscopic imaging lens group 25, and a detector image plane 36 arranged sequentially along the reflected optical path of the third beam splitter 16.

[0092] See Figure 3 The light propagation path of the first detection optical path is as follows: laser source 1, laser mirror group 2, integrating rod 3, collimating lens group 4, polarizer 5, first beam splitter 6, first quarter-wave plate 7, second beam splitter 8, second quarter-wave plate 9, first aperture 26, first focusing imaging lens group 10, first target 100, first focusing imaging lens group 10, first aperture 26, second quarter-wave plate 9, second beam splitter 8, optical path compensation plate 14, first half-wave plate 15, third beam splitter 16. 28. Third aperture, 17. Fourth quarter-wave plate, 18. Refracting mirror group, 31. First imaging plane, 19. Catadioptric mirror group, 32. Catadioptric mirror group, 19. First imaging plane, 31. Refracting mirror group, 18. Fourth quarter-wave plate, 17. Third aperture, 28. Third beam splitter, 16. Second half-wave plate, 20. Fourth beam splitter, 21. Fifth aperture, 30. Fourth focusing imaging mirror group, 24. Third imaging plane, 33. Microscopic imaging mirror group, 25. Detector image plane, 36.

[0093] In some embodiments of this application, see Figure 12 The first aperture 26 is provided with a first light-transmitting hole 261, a second light-transmitting hole 262, and a third light-transmitting hole 263. The third light-transmitting hole 263 is located at the center of the first aperture 26. The second light-transmitting hole 262 and the first light-transmitting hole 261 are symmetrically arranged along the Y direction and are aligned with the +1st order diffracted light and -1st order diffracted light generated by the first grating texture 110, respectively. The third light-transmitting hole 263 is used to transmit incident light, while the first light-transmitting hole 261 and the second light-transmitting hole 262 are used to transmit the +1st order diffracted light and -1st order diffracted light generated by the first grating texture 110 on the first target 100.

[0094] In some embodiments of this application, see Figure 4 The second detection optical path includes: a laser source 1, a laser mirror group 2, an integrating rod 3, a collimating lens group 4, a polarizer 5, a first beam splitter 6, a first quarter-wave plate 7, and a second beam splitter 8 arranged sequentially along the optical path direction; a third quarter-wave plate 11, a second aperture 27, a second focusing imaging lens group 12, and a second target 200 arranged sequentially along the transmission optical path of the second beam splitter 8; an optical path compensation plate 14, a first half-wave plate 15, a third beam splitter 16, a third aperture 28, a fourth quarter-wave plate 17, a refractor mirror group 18, a first imaging image plane 31, a catadioptric mirror group 19, and a second imaging image plane 32 arranged sequentially along the opposite direction of the reflection optical path of the second beam splitter 8; and a second half-wave plate 20, a fourth beam splitter 21, a fifth aperture 30, a fourth focusing imaging lens group 24, a fourth imaging image plane 34, a microscope imaging lens group 25, and a detector image plane 36 arranged sequentially along the reflection optical path of the third beam splitter 16.

[0095] See Figure 4 The light propagation path of the second detection optical path is as follows: laser source 1, laser mirror group 2, integrating rod 3, collimating lens group 4, polarizer 5, first beam splitter 6, first quarter-wave plate 7, second beam splitter 8, third quarter-wave plate 11, second aperture 27, second focusing imaging lens group 12, second target 200, second focusing imaging lens group 12, second aperture 27, third quarter-wave plate 11, second beam splitter 8, optical path compensation plate 14, first half-wave plate 15, third beam splitter 1 6. Third aperture 28, fourth quarter-wave plate 17, refracting mirror group 18, first imaging plane 31, catadioptric mirror group 19, second imaging plane 32, catadioptric mirror group 19, first imaging plane 31, refracting mirror group 18, fourth quarter-wave plate 17, third aperture 28, third beam splitter prism 16, second half-wave plate 20, fourth beam splitter prism 21, fifth aperture 30, fourth focusing imaging mirror group 24, fourth imaging plane 34, microscope imaging mirror group 25, detector image plane 36.

[0096] In some embodiments of this application, see Figure 13 The second aperture 27 is provided with a fourth light-transmitting hole 271, a fifth light-transmitting hole 272, and a sixth light-transmitting hole 273. The sixth light-transmitting hole 273 is located at the center of the second aperture 27. The fourth light-transmitting hole 271 and the fifth light-transmitting hole 272 are symmetrically arranged along the X direction and are aligned with the +1st order diffracted light and -1st order diffracted light generated by the second grating texture 210, respectively. The sixth light-transmitting hole 273 is used to transmit incident light, while the fifth light-transmitting hole 272 and the fourth light-transmitting hole 271 are used to transmit the +1st order diffracted light and -1st order diffracted light generated by the second grating texture 210 on the second target 200, respectively.

[0097] In some embodiments of this application, see Figure 5 The third detection optical path includes: a laser source 1, a laser mirror group 2, an integrating rod 3, a collimating lens group 4, a polarizer 5, and a first beam splitter 6 arranged sequentially along the optical path direction; a third half-wave plate 13, a fourth beam splitter 21, a fifth quarter-wave plate 22, a fourth aperture 29, a third focusing imaging lens group 23, and a third target 300 arranged sequentially along the reflected optical path of the first beam splitter 6; and a fifth aperture 30, a fourth focusing imaging lens group 24, a fifth imaging image plane 35, a microscopic imaging lens group 25, and a detector image plane 36 arranged sequentially along the reflected optical path of the fourth beam splitter 21.

[0098] The light propagation path of the third detection optical path is as follows: laser source 1, laser mirror group 2, integrating rod 3, collimating lens group 4, polarizer 5, first beam splitter 6, third half-wave plate 13, fourth beam splitter 21, fifth quarter-wave plate 22, fourth aperture 29, third focusing imaging lens group 23, third target 300, third focusing imaging lens group 23, fourth aperture 29, fifth quarter-wave plate 22, fourth beam splitter 21, fifth aperture 30, fourth focusing imaging lens group 24, fifth imaging plane 35, microscopic imaging lens group 25, detector image plane 36.

[0099] In this application, the three detection optical paths share a single laser source 1. On the one hand, this avoids the errors caused by using multiple light sources and improves detection accuracy. On the other hand, it also simplifies the structure of the device and reduces the space occupied.

[0100] In some embodiments of this application, see Figure 15The surface of the fourth aperture 29 is provided with a light-absorbing material. The fourth aperture 29 is provided with an eleventh light-transmitting hole 291, a twelfth light-transmitting hole 292, a thirteenth light-transmitting hole 293, a fourteenth light-transmitting hole 294 and a fifteenth light-transmitting hole 295. The twelfth light-transmitting hole 292 and the eleventh light-transmitting hole 291 are symmetrically distributed along the Y direction and are aligned with the +1st order diffraction light and the -1st order diffraction light generated by the third grating texture 310, respectively. The fourteenth light-transmitting hole 294 and the thirteenth light-transmitting hole 293 are symmetrically distributed along the X direction and are aligned with the +1st order diffraction light and the -1st order diffraction light generated by the fourth grating texture 320, respectively. The fifteenth light-transmitting hole 295 is located at the center of the fourth aperture 29.

[0101] The twelfth and eleventh light-transmitting holes 292 and 291 are respectively used for the +1st and -1st order diffraction light generated by the third grating texture 310 on the third target 300 to pass through. The fourteenth and thirteenth light-transmitting holes 294 and 293 are respectively used for the +1st and -1st order diffraction light generated by the fourth grating texture 320 on the third target 300 to pass through. The 0th order diffraction light is transmitted through the fifteenth light-transmitting hole 295.

[0102] In some embodiments of this application, see Figure 14 The surface of the third aperture 28 is provided with a light-absorbing material. The third aperture 28 is provided with a seventh light-transmitting hole 281, an eighth light-transmitting hole 282, a ninth light-transmitting hole 283 and a tenth light-transmitting hole 284. The seventh light-transmitting hole 281 and the eighth light-transmitting hole 282 are symmetrically arranged along the Y direction and are aligned with the -1st order diffraction light and the +1st order diffraction light generated by the first grating texture 110, respectively. The ninth light-transmitting hole 283 and the tenth light-transmitting hole 284 are symmetrically arranged along the X direction and are aligned with the -1st order diffraction light and the +1st order diffraction light generated by the second grating texture 210, respectively.

[0103] The seventh and eighth light-transmitting holes 281 and 282 are used to allow the +1st and -1st order diffracted light generated by the first grating texture 110 on the first target 100 to pass through, respectively, while the 0th order diffracted light is absorbed by the surface of the third aperture 28. The tenth and ninth light-transmitting holes 284 and 283 are used to allow the +1st and -1st order diffracted light generated by the second grating texture 210 on the second target 200 to pass through, respectively, while the 0th order diffracted light is absorbed by the surface of the third aperture 28.

[0104] In some embodiments of this application, see Figure 17The surface of the optical path compensation plate 14 is coated with an antireflection film. The optical path compensation plate 14 has a first hollowed-out region 141 and a second hollowed-out region 142, which are aligned with the +1st order diffracted light and -1st order diffracted light generated by the second grating texture 210, respectively. Linearly polarized P-beams in the first detection optical path pass through the portion of the optical path compensation plate 14 coated with the antireflection film, achieving optical path compensation. Linearly polarized S-beams in the second detection optical path can pass through the first hollowed-out region 141 and the second hollowed-out region 142.

[0105] In some embodiments of this application, see Figure 18 The first half-wave plate 15 is coated with an anti-reflection film. A third hollow region 151 and a fourth hollow region 152 are provided on the first half-wave plate 15, and these regions are aligned with the +1st and -1st order diffracted light generated by the first grating texture 110, respectively. Linearly polarized P-light in the first detection optical path remains linearly polarized P-light after passing through the third hollow region 151 and the fourth hollow region 152. Linearly polarized S-light in the second detection optical path experiences a π-phase delay after passing through the portion of the first half-wave plate 15 coated with the anti-reflection film, and is converted into linearly polarized P-light.

[0106] In some embodiments of this application, the spatial angle between the fast axis of the first half-wave plate 15 and the transmission axis of the second beam splitter 8 is 45 degrees.

[0107] In some embodiments of this application, the third beam splitter 16 is a polarizing beam splitter, and the P-light transmission axis of the third beam splitter 16 coincides with the transmission P-light transmission axis of the second beam splitter 8.

[0108] In some embodiments of this application, the spatial angle between the fast axis of the fourth quarter-wave plate 17 and the transmission axis of the transmitted P-beam of the third beam splitter 16 is 45 degrees.

[0109] In some embodiments of this application, the spatial angle between the fast axis of the second half-wave plate 20 and the reflected S-ray transmission axis of the third beam splitter 16 is 45 degrees.

[0110] In some embodiments of this application, the spatial angle between the fast axis of the third half-wave plate 13 and the reflected S-ray transmission axis of the first beam splitter 6 is 45 degrees.

[0111] In some embodiments of this application, the optical path compensation plate 14, the first half-wave plate 15, the second half-wave plate 20, the third half-wave plate 13, and the fourth quarter-wave plate 17 are all made of fused silica. It is understood that other materials may be used in other embodiments.

[0112] In some embodiments of this application, see Figure 16 The fifth aperture 30 is provided with a sixteenth light-transmitting hole 301, a seventeenth light-transmitting hole 302, an eighteenth light-transmitting hole 303 and a nineteenth light-transmitting hole 304. The surface of the fifth aperture 30 is coated with a light-absorbing material. The seventeenth light-transmitting hole 302 and the sixteenth light-transmitting hole 301 are symmetrically arranged along the Y direction and are aligned with the +1st order diffraction light and -1st order diffraction light generated by the third grating texture 310, respectively. The nineteenth light-transmitting hole 304 and the eighteenth light-transmitting hole 303 are symmetrically arranged along the X direction and are aligned with the +1st order diffraction light and -1st order diffraction light generated by the fourth grating texture 320, respectively.

[0113] The +1st and -1st order diffracted lights generated by the fourth grating texture 320 pass through the nineteenth and eighteenth light-transmitting holes 304 and 303, respectively. The +1st and -1st order diffracted lights generated by the third grating texture 310 pass through the seventeenth and sixteenth light-transmitting holes 302 and 301, respectively. The 0th order diffracted light is absorbed by the surface of the fifth aperture 30. It should be noted that the +1st and -1st order diffracted lights generated by the second grating texture 210 also pass through the nineteenth and eighteenth light-transmitting holes 304 and 303, respectively, and the +1st and -1st order diffracted lights generated by the first grating texture 110 also pass through the seventeenth and sixteenth light-transmitting holes 302 and 301, respectively.

[0114] In some embodiments of this application, the spatial angle between the transmission axis of the transmitted P-light of the fourth beam splitter 21 and the fast axis of the fifth quarter-wave plate 22 is 45 degrees.

[0115] In some embodiments of this application, the laser source 1 is an ultraviolet laser source 1.

[0116] In some embodiments of this application, the integral bar 3 is a cuboid fused quartz rod with a square cross-section and sharp edges without chamfers.

[0117] In some embodiments of this application, the first beam splitter 6 is a common beam splitter with a transmitted light energy to reflected light energy ratio of 70%:30%. It is understood that in other embodiments, other ratios of transmittance and reflection can also be set.

[0118] In another embodiment of this application, the first beam splitter 6 can also be configured as a polarizing beam splitter. In this case, a quarter-wave plate needs to be added between the first beam splitter 6 and the collimating lens group 4 to convert linearly polarized light into circularly polarized light or elliptically polarized light.

[0119] The first detection optical path, according to the light propagation path and polarization state conversion, is as follows: Laser source 1 provides stable light source output; laser mirror group 2 realizes the light source NA scaling function; integrating rod 3 realizes beam homogenization to make the light spot uniform; collimating lens group 4 realizes beam collimation; polarizer 5 realizes polarization state conversion to output linearly polarized light (S-beam); the first beam splitter 6 is a common beam splitter prism, which proportionally distributes the incident light energy into transmitted light and reflected light; the first quarter-wave plate 7 converts the incident linearly polarized light (S-beam) into circularly polarized light; the second beam splitter prism 8 is a polarization beam splitter prism, which reflects the incident circularly polarized light into linearly polarized light (S-beam); the second quarter-wave plate 9 converts the incident linearly polarized light (S-beam) into circularly polarized light; the third light-transmitting aperture 263 on the first aperture 26 transmits the incident light; the first focusing imaging lens group 10 realizes focusing imaging; the light is incident directly on the first grating texture 110 on the first target 100, and the incident light is diffracted into +1st order diffracted light, -1st order diffracted light, and -2nd order diffracted light. The +1st and -1st order diffracted beams, along with the ±1st order diffracted beams along the Y direction, undergo a π phase delay on the surface of the first target 100, resulting in reverse circularly polarized light. The first focusing imaging lens group 10 collimates the +1st, -1st, and -0th order diffracted beams returned from the first target 100, maintaining their circular polarization. These beams then pass through the second light-transmitting aperture 2 in region 100. 62. The first and third light-transmitting holes 261 and 263 transmit circularly polarized light. The second quarter-wave plate 9 converts the incident circularly polarized light into linearly polarized P-light. The second beam splitter 8 transmits the linearly polarized P-light. The linearly polarized P-light passes through the non-hollowed-out area of ​​the optical path compensation plate 14 for optical path compensation. Then, the linearly polarized P-light passes through the third hollowed-out area 151 and the fourth hollowed-out area 152 on the first half-wave plate 15 and exits as linearly polarized P-light. The third beam splitter 16 is a polarization beam splitter that transmits the incident linearly polarized P-light. The +1st and -1st order diffracted light generated by the first grating texture 110 of the first target 100 passes through the eighth and seventh light-transmitting holes 282 and 281 on the third aperture 28, respectively. The 0th order diffracted light is absorbed by the non-hollowed-out area of ​​the third aperture 28 and becomes linearly polarized P-light. The fourth quarter-wave plate 17 converts the incident linearly polarized P-beam into circularly polarized light. The refracting mirror group 18 images the light onto the first imaging plane 31, resulting in circularly polarized light. The catadioptric mirror group 19 performs a second imaging, causing a π-phase delay on the reflective surface of the second imaging plane 32, converting the polarization state to reverse circularly polarized light. The catadioptric mirror group 19 images the light onto the first imaging plane 31, and the refracting mirror group 18 collimates the light, resulting in circularly polarized light. The fourth quarter-wave plate 17 converts the circularly polarized light into linearly polarized S-beam. The +1st and -1st order diffracted light generated by the first grating texture 110 of the first target 100 passes through the seventh and eighth transmission holes 281 and 282 on the third aperture 28, respectively, resulting in linearly polarized S-beam.The third beam splitter 16 reflects the incident linearly polarized S-beam, and the second half-wave plate 20 generates a π phase delay, converting the incident linearly polarized S-beam into linearly polarized P-beam. The fourth beam splitter 21 is a polarization beam splitter that transmits the incident linearly polarized P-beam. Through the seventeenth and sixteenth apertures 302 and 301 on the fifth aperture 30, the polarization state is linearly polarized P-beam. The fourth focusing imaging lens group 24 achieves focused imaging, imaging the first grating texture 110 of the right field of view of the first target 100 three times onto the third imaging plane 33, with the polarization state being linearly polarized P-beam. The microscopic imaging lens group 25 magnifies and images the moiré fringes onto the detector image plane 36.

[0120] The second detection optical path, according to the light propagation path and polarization state conversion, is as follows: Laser source 1 provides stable light source output; laser mirror group 2 realizes the light source NA scaling function; integrating rod 3 realizes beam homogenization to make the light spot uniform; collimating lens group 4 realizes beam collimation; polarizer 5 realizes polarization state conversion to output linearly polarized light (S-beam). The first beam splitter 6 is a common beam splitter prism, which proportionally distributes the incident light energy into transmitted light and reflected light; the first quarter-wave plate 7 converts the incident linearly polarized light (S-beam) into circularly polarized light; the second beam splitter prism 8 is a polarization beam splitter prism, which transmits the incident circularly polarized light as linearly polarized light (P-beam). The third quarter-wave plate 11 converts the incident linearly polarized light (P-beam) into circularly polarized light; and the sixth light-transmitting aperture 273 on the second aperture 27 transmits the incident light. The second focusing imaging lens group 12 achieves focused imaging. The light is incident normally and is circularly polarized. The second grating texture 210 region on the second target 200 diffracts the normally incident light into +1st order, -1st order, and 0th order diffracted light. The ±1st order diffracted light is along the X-direction, and its phase undergoes a π-phase delay on the surface of the second target 200, resulting in reverse circularly polarized light. The second focusing imaging lens group 12 collimates the +1st order, -1st order, and 0th order diffracted light returned from the second target 200, resulting in circularly polarized light. The +1st order, -1st order, and 0th order diffracted light returned from the second target 200 pass through the fifth, fourth, and sixth transmission holes 272, 271, and 273 on the second aperture 27, respectively, resulting in circularly polarized light. The third quarter-wave plate 11 converts the incident circularly polarized light into linearly polarized S-beams. The second beam splitter prism 8 reflects linearly polarized S-beams. The linearly polarized S-beams pass through the first and second cutout regions 141 and 142 on the optical path compensation plate 14, and are then polarized as linearly polarized S-beams. The linearly polarized S-beams pass through the non-cutout region of the first half-wave plate 15, resulting in a π-phase delay and conversion into linearly polarized P-beams. The third beam splitter prism 16, a polarization beam splitter, transmits the incident linearly polarized P-beams. The +1st and -1st order diffracted beams generated by the second grating texture 210 on the second target 200 pass through the tenth and ninth apertures 284 and 283 on the third aperture 28, respectively. The 0th order diffracted beam is absorbed by the non-cutout region of the third aperture 28, and is also polarized as linearly polarized P-beams. The fourth quarter-wave plate 17 converts the incident linearly polarized P-beams into circularly polarized light. The refracting mirror group 18 images the light onto the first imaging plane 31, and the light is then circularly polarized. The catadioptric mirror group 19 performs a second imaging of the light path. The reflective surface of the second imaging plane 32 experiences a π-phase delay, converting the polarization state into reverse circularly polarized light. The catadioptric mirror group 19 achieves optical path imaging onto the first imaging plane 31, and the refracting mirror group 18 achieves optical path collimation, resulting in circularly polarized light. The fourth quarter-wave plate 17 converts the circularly polarized light into linearly polarized S-rays.The +1st and -1st order diffracted light generated by the second grating texture 210 on the second target 200 passes through the tenth and ninth transmission holes 284 and 283 on the third aperture 28, respectively, and is linearly polarized (S-beam). The third beam splitter 16 reflects the incident linearly polarized (S-beam), and the second half-wave plate 20 causes a π-phase delay in the light, converting the incident linearly polarized (S-beam) into linearly polarized (P-beam). The fourth beam splitter 21 is a polarization beam splitter that transmits the incident linearly polarized (P-beam). Passing through the nineteenth and eighteenth transmission holes 304 and 303 on the fifth aperture 30, the polarization state is linearly polarized (P-beam). The fourth focusing imaging lens group 24 achieves focused imaging, imaging the second grating texture 210 in the left field of view of the second target 200 three times onto the fourth imaging plane 34, with the polarization state being linearly polarized (P-beam). The microscopic imaging lens group 25 magnifies and images the moiré fringes onto the detector image plane 36.

[0121] The third detection optical path, according to the light propagation path and polarization state conversion, is as follows: Laser source 1 provides stable light source output; laser mirror group 2 realizes the light source NA scaling function; integrating rod 3 realizes beam homogenization to make the light spot uniform; collimating lens group 4 realizes beam collimation; polarizer 5 realizes polarization state conversion to output linearly polarized light (S-beam). The first beam splitter 6 is a common beam splitter prism, which proportionally distributes the incident light energy into transmitted light and reflected light; the third half-wave plate 13 generates π phase delay, converting the linearly polarized light (S-beam) into linearly polarized light (P-beam). The fourth beam splitter 21 is a polarization beam splitter prism, which transmits the incident linearly polarized light (P-beam). The fifth quarter-wave plate 22 converts the incident linearly polarized light (P-beam) into circularly polarized light; the fifteenth aperture 295 at the center of the fourth aperture 29 transmits the incident light; and the third focusing imaging lens group 23 realizes focusing imaging, with the light incident normally and the polarization state being circularly polarized light. The fourth grating texture 320 region on the third target 300 diffracts normally incident light into +1st order, -1st order, and 0th order diffracted light, with the ±1st order diffracted light along the X direction. The third grating texture 310 region diffracts normally incident light into +1st order, -1st order, and 0th order diffracted light, with the ±1st order diffracted light along the Y direction. The light phase undergoes a π phase delay on the surface of the third target 300, and the polarization state is reverse circularly polarized light. The third focusing imaging lens group 23 collimates the ±1st order and 0th order diffracted light generated by the fourth grating texture 320 and the third grating texture 310, and the polarization state is circularly polarized light. The +1st and -1st order diffracted light generated by the fourth grating texture 320 passes through the fourteenth and thirteenth transmission holes 294 and 293 on the fourth aperture 29, respectively. The +1st and -1st order diffracted light generated by the third grating texture 310 passes through the twelfth and eleventh transmission holes 292 and 291 on the fourth aperture 29, respectively. The 0th order diffracted light is transmitted through the central fifteenth transmission hole 295, and the polarization state is circularly polarized light. The fifth quarter-wave plate 22 converts the incident circularly polarized light into linearly polarized S-light, and the fourth beam splitter prism 21 is a polarizing beam splitter that reflects the incident linearly polarized S-light. The +1st and -1st order diffracted light generated by the fourth grating texture 320 passes through the nineteenth and eighteenth transmission holes 304 and 303 on the fifth aperture 30, respectively. The +1st and -1st order diffracted light generated by the third grating texture 310 passes through the seventeenth and sixteenth transmission holes 302 and 301 on the fifth aperture 30, respectively. The 0th order diffracted light is absorbed by the non-cutout area of ​​the fifth aperture 30, and its polarization state is linearly polarized S-beam. The fourth focusing imaging lens group 24 achieves focused imaging, and re-images the grating textures (i.e., the fourth grating texture 320 and the third grating texture 310) in the field of view of the third target 300 onto the fifth imaging image plane 35, with the polarization state being linearly polarized S-beam. The microscopic imaging lens group 25 magnifies and images the moiré fringes onto the detector image plane 36.

[0122] See Figure 1The first grating texture 110 in the right field of view of the first target 100 has its ±1st order diffracted light imaged into a third imaging plane 33 via a first detection optical path. The third grating texture 310 in the right field of view of the third target 300 has its ±1st order diffracted light imaged into a fifth imaging plane 35 via a third detection optical path. The third imaging plane 33 and the fifth imaging plane 35 are superimposed to form a first moiré fringe, the texture of which is along the X direction. By performing phase calculation on the first moiré fringe, X-nanometer-level warpage detection of the wafer surface can be achieved. Figure 19 This is a schematic diagram of the first moiré fringe of the present invention.

[0123] See Figure 1 The second grating texture 210 in the left field of view of the second target 200 has its ±1st order diffracted light imaged into the fourth imaging plane 34 through the second detection optical path. The fourth grating texture 320 in the left field of view of the third target 300 has its ±1st order diffracted light imaged into the fifth imaging plane 35 through the third detection optical path. The fourth imaging plane 34 and the fifth imaging plane 35 are superimposed to form the second moiré fringe. The second moiré fringe texture is along the Y direction. By performing phase calculation on the second moiré fringe, the Y-nanometer warpage detection of the wafer surface can be achieved. Figure 20 This is a schematic diagram of the second moiré fringe of the present invention.

[0124] The superimposed moiré fringes are magnified by the microscope imaging lens group 25 and imaged onto the detector image plane 36. The detector image plane 36 observes the moiré fringes along the Y direction in the left field of view and the moiré fringes along the X direction in the right field of view. Figure 21 This is a schematic diagram of the total moiré fringes of the present invention.

[0125] The various embodiments or implementation methods described in this specification are presented in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0126] It should be noted that the terms "one embodiment," "embodiment," "exemplary embodiment," "some embodiments," etc., mentioned in the specification indicate that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not, is within the knowledge scope of those skilled in the art.

[0127] Finally, it should be noted that other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and alterations may be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. An apparatus for detecting warpage on a wafer surface, characterized in that, include: A first detection optical path is provided in the first detection optical path, and a first target (100) is provided in the right field of view of the first target (100) along the X direction. The first detection optical path is used to illuminate the first grating texture (110) to generate a first diffraction light along the Y direction. A second detection optical path is provided in which a second target (200) is provided. The left field of view of the second target (200) is provided with a second grating texture (210) along the Y direction, and the Y direction is perpendicular to the X direction. The second detection optical path is used to illuminate the second grating texture (210) to generate a second diffracted light along the X direction. A third detection optical path is provided in which a third target (300) is provided. The right field of view of the third target (300) is provided with a third grating texture (310) along the X direction, and the left field of view of the third target (300) is provided with a fourth grating texture (320) along the Y direction. The third detection optical path is used to illuminate the third grating texture (310) and the fourth grating texture (320) respectively to generate third diffraction light along the Y direction and fourth diffraction light along the X direction. The first diffracted light and the third diffracted light superimpose to form a first moiré fringe, and the second diffracted light and the fourth diffracted light superimpose to form a second moiré fringe.

2. The apparatus for wafer surface warpage detection according to claim 1, wherein, a stripe period P of the first moire fringe M1 satisfies the following relationship: ； Wherein, P1 is the grating period of the first grating texture (110), and P3 is the grating period of the third grating texture (310).

3. The apparatus for wafer surface warpage detection according to claim 1, wherein, a stripe period P of the second moire fringe M2 satisfies the following relationship: ； Wherein, P2 is the grating period of the second grating texture (210), and P4 is the grating period of the fourth grating texture (320).

4. The apparatus for detecting wafer surface warpage according to claim 1, characterized in that, The first detection optical path includes: The laser source (1), laser mirror group (2), integrating rod (3), collimating lens group (4), polarizer (5), first beam splitter (6), first quarter-wave plate (7), and second beam splitter (8) are arranged sequentially along the optical path. The second quarter-wave plate (9), the first aperture (26), the first focusing imaging lens group (10), and the first target (100) are arranged sequentially along the reflected light path of the second beam splitter (8). Optical path compensation plate (14), first half-wave plate (15), third beam splitter (16), third aperture (28), fourth quarter-wave plate (17), refractor group (18), first imaging plane (31), catadioptric mirror group (19), and second imaging plane (32) are arranged sequentially in the opposite direction to the reflected light path of the second beam splitter (8). The second half-wave plate (20), the fourth beam splitter (21), the fifth aperture (30), the fourth focusing imaging mirror group (24), the third imaging image plane (33), the microscopic imaging mirror group (25), and the detector image plane (36) are arranged sequentially along the reflected light path of the third beam splitter (16).

5. The apparatus for detecting wafer surface warpage according to claim 4, characterized in that, The first aperture (26) is provided with a first light-transmitting hole (261), a second light-transmitting hole (262) and a third light-transmitting hole (263). The third light-transmitting hole (263) is located at the center of the first aperture (26). The second light-transmitting hole (262) and the first light-transmitting hole (261) are symmetrically arranged along the Y direction and are aligned with the +1 order diffraction light and -1 order diffraction light generated by the first grating texture (110) respectively.

6. The apparatus for wafer surface bow detection of claim 1, wherein, The second detection optical path includes: The laser source (1), laser mirror group (2), integrating rod (3), collimating lens group (4), polarizer (5), first beam splitter (6), first quarter-wave plate (7), and second beam splitter (8) are arranged sequentially along the optical path. The third quarter-wave plate (11), the second aperture (27), the second focusing imaging lens group (12), and the second target (200) are arranged sequentially along the transmission light path of the second beam splitter (8). Optical path compensation plate (14), first half-wave plate (15), third beam splitter (16), third aperture (28), fourth quarter-wave plate (17), refractor group (18), first imaging plane (31), catadioptric mirror group (19), and second imaging plane (32) are arranged sequentially in the opposite direction to the reflected light path of the second beam splitter (8). The second half-wave plate (20), the fourth beam splitter (21), the fifth aperture (30), the fourth focusing imaging mirror group (24), the fourth imaging image plane (34), the microscopic imaging mirror group (25), and the detector image plane (36) are arranged sequentially along the reflected light path of the third beam splitter (16).

7. The apparatus for wafer surface warpage detection according to claim 6, wherein, The second aperture (27) is provided with a fourth light-transmitting hole (271), a fifth light-transmitting hole (272) and a sixth light-transmitting hole (273). The sixth light-transmitting hole (273) is located at the center of the second aperture (27). The fifth light-transmitting hole (272) and the fourth light-transmitting hole (271) are symmetrically arranged along the X direction and are aligned with the +1st order diffraction light and the -1st order diffraction light generated by the second grating texture (210) respectively.

8. The apparatus for wafer surface bow detection of claim 1, wherein, The third detection optical path includes: The laser source (1), laser mirror group (2), integrating rod (3), collimating lens group (4), polarizer (5), and first beam splitter (6) are arranged sequentially along the optical path. The third half-wave plate (13), the fourth beam splitter (21), the fifth quarter-wave plate (22), the fourth aperture (29), the third focusing imaging lens group (23), and the third target (300) are arranged sequentially along the reflected light path of the first beam splitter (6). The fifth aperture (30), the fourth focusing imaging mirror group (24), the fifth imaging image plane (35), the microscopic imaging mirror group (25), and the detector image plane (36) are arranged sequentially along the reflected light path of the fourth beam splitter (21).

9. The apparatus for detecting wafer surface warpage according to claim 8, characterized in that, The surface of the fourth aperture (29) is provided with a light-absorbing material. The fourth aperture (29) is provided with an eleventh light-transmitting hole (291), a twelfth light-transmitting hole (292), a thirteenth light-transmitting hole (293), a fourteenth light-transmitting hole (294) and a fifteenth light-transmitting hole (295). The twelfth light-transmitting hole (292) and the eleventh light-transmitting hole (291) are symmetrically distributed along the Y direction and are aligned with the +1st order diffraction light and the -1st order diffraction light generated by the third grating texture (310), respectively. The fourteenth light-transmitting hole (294) and the thirteenth light-transmitting hole (293) are symmetrically distributed along the X direction and are aligned with the +1st order diffraction light and the -1st order diffraction light generated by the fourth grating texture (320), respectively. The fifteenth light-transmitting hole (295) is located at the center of the fourth aperture (29).

10. The apparatus for detecting wafer surface warpage according to any one of claims 4-7, characterized in that, The surface of the third aperture (28) is provided with a light-absorbing material. The third aperture (28) is provided with a seventh light-transmitting hole (281), an eighth light-transmitting hole (282), a ninth light-transmitting hole (283) and a tenth light-transmitting hole (284). The seventh light-transmitting hole (281) and the eighth light-transmitting hole (282) are symmetrically arranged along the Y direction and are aligned with the -1st order diffraction light and the +1st order diffraction light generated by the first grating texture (110), respectively. The ninth light-transmitting hole (283) and the tenth light-transmitting hole (284) are symmetrically arranged along the X direction and are aligned with the -1st order diffraction light and the +1st order diffraction light generated by the second grating texture (210), respectively.

11. The apparatus for wafer surface warpage detection according to any one of claims 4-7, wherein, The surface of the optical path compensation plate (14) is coated with an anti-reflection film. The optical path compensation plate (14) is provided with a first hollow area (141) and a second hollow area (142). The first hollow area (141) and the second hollow area (142) are respectively aligned with the +1 order diffraction light and the -1 order diffraction light generated by the second grating texture (210).

12. The apparatus for detecting wafer surface warpage according to any one of claims 4-7, characterized in that, The first half-wave plate (15) is coated with an anti-reflection film. The first half-wave plate (15) is provided with a third hollow area (151) and a fourth hollow area (152). The third hollow area (151) and the fourth hollow area (152) are respectively aligned with the +1 order diffraction light and the -1 order diffraction light generated by the first grating texture (110).

13. The apparatus for detecting wafer surface warpage according to any one of claims 4-7, characterized in that, The spatial angle between the fast axis of the first half-wave plate (15) and the transmission axis of the P-light transmitted by the second beam splitter (8) is 45 degrees.

14. The apparatus for wafer surface warpage detection according to any one of claims 4-7, wherein, The third beam splitter (16) is a polarizing beam splitter, and the P-light transmission axis of the third beam splitter (16) coincides with the transmission P-light transmission axis of the second beam splitter (8).

15. The apparatus for detecting wafer surface warpage according to any one of claims 4-7, characterized in that, The spatial angle between the fast axis of the fourth quarter-wave plate (17) and the transmission P-light transmission axis of the third beam splitter (16) is 45 degrees.

16. The apparatus for detecting wafer surface warpage according to any one of claims 4-7, characterized in that, The spatial angle between the fast axis of the second half-wave plate (20) and the reflected S-ray transmission axis of the third beam splitter (16) is 45 degrees.

17. The apparatus for detecting wafer surface warpage according to any one of claims 8-9, characterized in that, The spatial angle between the fast axis of the third half-wave plate (13) and the reflected S-ray transmission axis of the first beam splitter (6) is 45 degrees.

18. The apparatus for detecting wafer surface warpage according to any one of claims 4, 6, and 8, characterized in that, The fifth aperture (30) is provided with a sixteenth light-transmitting hole (301), a seventeenth light-transmitting hole (302), an eighteenth light-transmitting hole (303) and a nineteenth light-transmitting hole (304). The surface of the fifth aperture (30) is coated with a light-absorbing material. The seventeenth light-transmitting hole (302) and the sixteenth light-transmitting hole (301) are symmetrically arranged along the Y direction and are aligned with the +1st order diffraction light and -1st order diffraction light generated by the third grating texture (310), respectively. The nineteenth light-transmitting hole (304) and the eighteenth light-transmitting hole (303) are symmetrically arranged along the X direction and are aligned with the +1st order diffraction light and -1st order diffraction light generated by the fourth grating texture (320), respectively.

19. The apparatus for detecting wafer surface warpage according to any one of claims 4, 6, and 8, characterized in that, The spatial angle between the transmission P-light transmission axis of the fourth beam splitter (21) and the fast axis of the fifth quarter-wave plate (22) is 45 degrees.

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