Anti-interference phase disturbance module and wafer warpage measurement system

Abstract

This invention relates to the field of semiconductor measurement technology, providing an anti-interference phase disturbance module and a wafer warpage measurement system. The anti-interference phase disturbance module includes a housing, a phase disturbance element, and a driving mechanism; both the phase disturbance element and the driving mechanism are located within the housing; the driving mechanism has a fixed end and a moving end; the fixed end is connected to the housing; the moving end is connected to the phase disturbance element, and when the driving mechanism is activated, the moving end moves relative to the fixed end to drive the phase disturbance element to perform mechanical movement; the phase disturbance element is located in the laser path for measuring the wafer warpage; during mechanical movement, the phase disturbance element disrupts the spatial coherence of the incident laser to obtain the emitted laser; the emitted laser is used to irradiate the surface of the wafer to measure the wafer warpage. The technical solution of this invention can maintain a stable brightness distribution of the light spot during the measurement process, thereby enhancing the continuity of wafer warpage calculation.

Description

Technical Field

[0001] This invention relates to the field of semiconductor measurement technology, specifically to an anti-interference phase disturbance module and a wafer warpage measurement system. Background Technology

[0002] Among related technologies, the two-point laser reflection method is the most commonly used in-situ warpage measurement method. This method involves two parallel laser beams incident at a small angle onto the surface of a growing epitaxial wafer. After reflection, the images are projected onto a camera, and the radius of curvature is calculated by the change in distance between the two laser spots. However, due to the high coherence of lasers, interference occurs between the two reflected beams and stray light from each beam on the camera target surface. When the growth of the thin film on the epitaxial wafer surface causes changes in the optical path difference, the interference pattern exhibits alternating bright and dark areas, affecting the continuity of the wafer warpage calculation.

[0003] Metal-Organic Chemical Vapor Deposition (MOCVD) is a core process for fabricating epitaxial wafers of compound semiconductors such as gallium nitride and gallium arsenide. During epitaxial growth, lattice mismatch and thermal mismatch between the substrate and the epitaxial layer cause warping deformation on the wafer surface. Real-time monitoring of this warping curvature is crucial for accurately controlling growth parameters and ensuring film quality. Currently, the dual-point laser reflection method is the mainstream technique for in-situ warping measurement. It uses two parallel laser beams incident at a small angle onto the growing epitaxial wafer surface, which are then reflected and imaged onto a camera target. The curvature radius is derived from the change in the beam spacing. However, the high coherence of the lasers causes interference between the two reflected beams and their stray light on the camera target. As the film thickness on the epitaxial wafer surface changes, the optical path difference changes, resulting in a dynamic distribution of alternating bright and dark areas in the interference pattern. Especially at the moment of decoherence, the local brightness of the beams decreases sharply or even disappears completely, directly leading to the failure of curvature calculation, causing data gaps, and severely disrupting the continuity of process monitoring.

[0004] While existing technologies have proposed various solutions to address the aforementioned interference problem, all have drawbacks. Multi-wavelength laser switching schemes, although able to switch to another wavelength when one wavelength cancels out, still have time gaps during the switching process, potentially leading to data loss and increasing system complexity and cost. Low-coherence light sources, such as superluminescent diodes (SLDs) or white light sources, utilize extremely short coherence lengths to suppress interference, but their low output power, poor beam quality, and high cost make it difficult to maintain an effective signal-to-noise ratio under the large optical path difference conditions of MOCVD. Schemes involving dynamically adjusting camera gain or exposure cannot solve the signal-to-noise ratio collapse problem when light intensity completely cancels out, and frequent parameter switching is more likely to introduce image artifacts. While rotating frosted glass or vibrating mixing rods can reduce spatial coherence and smooth fringes through moving elements, they only perform well in laboratory environments at room temperature and in clean conditions, facing severe environmental adaptability challenges inside MOCVD machines.

[0005] The internal environment of the MOCVD reaction chamber is extremely harsh, with growth temperatures reaching 1000℃~1200℃, the presence of highly corrosive gases such as NH3, H2, and organometallic sources like trimethylgallium (TMGa) and trimethylaluminum (TMAl), and working pressures fluctuating from tens of millibars to atmospheric pressure. Furthermore, reaction byproducts easily form nanoscale particles that contaminate optical components. In addition, the external optical path of the reaction chamber is compact, and the internal space is highly limited. Integrating conventional phase-scratching elements such as rotating frosted glass and vibrating mixing rods directly into the MOCVD optical path presents several insurmountable technical obstacles: First, the high temperatures can cause deformation, carbonization, or even failure of ordinary optical adhesives, plastic components, or certain metal materials; second, the bearing friction of the rotating or vibrating mechanism inevitably generates fine particles, which, once entering the reaction zone and depositing on the epitaxial wafer surface, will directly lead to wafer growth failure; third, the inner walls of the reaction chamber and optical windows are easily covered by byproducts and fogged, severely obstructing light transmission. In summary, there is currently a lack of a phase disturbance module and wafer warpage measurement system that can adapt to the extreme operating conditions of MOCVD and is easy to deploy on existing MOCVD equipment. Summary of the Invention

[0006] The technical problem solved by this invention is to provide an anti-interference phase disturbance module and a wafer warpage measurement system, which can maintain a stable brightness distribution during spot measurement to enhance the continuity of wafer warpage calculation.

[0007] According to a first aspect of the present invention, an anti-interference phase disturbance module is provided for weakening laser coherence during wafer warpage measurement. The anti-interference phase disturbance module includes a housing, a phase disturbance element, and a driving mechanism. Both the phase disturbance element and the driving mechanism are located within the housing. The driving mechanism has a fixed end and a moving end. The fixed end is connected to the housing. The moving end is connected to the phase disturbance element. When the driving mechanism is activated, the moving end moves relative to the fixed end to drive the phase disturbance element to perform mechanical movement. The phase disturbance element is located in the laser path for measuring the wafer warpage. During mechanical movement, the phase disturbance element disrupts the spatial coherence of the incident laser to obtain an emitted laser. The emitted laser is used to irradiate the surface of the wafer to measure the wafer warpage.

[0008] The beneficial effects of this invention are as follows: By setting a phase-disrupting element driven by a driving mechanism in the laser optical path, the spatial coherence of the incident laser is rapidly changed by its mechanical movement, transforming the originally highly coherent laser into an incoherent or low-coherence light source. This dynamic modulation at the hardware level averages the bright and dark fringes in the interference pattern, weakens the local brightness fluctuations caused by small fluctuations in the optical path difference, and balances the two reflected light spots to maintain a stable brightness distribution throughout the measurement process, avoiding interruptions in wafer warpage calculation due to discontinuous brightness distribution.

[0009] In one embodiment, the anti-interference phase disturbance module further includes an external rotor; the external rotor is located outside the housing; the driving mechanism includes an internal rotor; the fixed end of the internal rotor is connected to the inner wall of the housing; the moving end of the internal rotor is rotatably connected to the fixed end; the external rotor and the internal rotor are coaxially arranged, and the external rotor acts on the moving end of the internal rotor through magnetic force; when the external rotor rotates, it drives the moving end of the internal rotor to rotate around the fixed end; the phase disturbance element is a frosted glass sheet; the position where the internal rotor is fixedly connected to the frosted glass sheet does not overlap with the position where the laser passes through the frosted glass sheet.

[0010] Its beneficial effect lies in achieving non-contact rotation of the phase disturbance element through magnetic coupling between the external and internal rotors. This design reduces friction, backlash, and micro-vibrations caused by mechanical transmission, improves the stability of the optical path system, and avoids measurement noise introduced by mechanical vibration.

[0011] In one embodiment, a gap is provided between the outer rotor and the outer wall of the housing; the housing is made of a non-magnetic material.

[0012] Its beneficial effects lie in the fact that by using a non-magnetic material to construct the housing and reserving a gap for the external rotor, a magnetic circuit isolation barrier is constructed. This design allows the magnetic field of the external rotor to penetrate the housing and drive the internal rotor, while effectively blocking the interference of the external magnetic field on the outer side of the housing and surrounding precision electronic components, preventing eddy current heating or signal noise. At the same time, the combination of the non-magnetic material and the gap avoids structural stress concentration caused by magnetic attraction, which helps to avoid the risk of housing deformation. While ensuring efficient transmission of magnetic drive, it also improves the electromagnetic compatibility and structural stability of the optical system.

[0013] In one embodiment, the frosted glass sheet has an edge region and a central region; the moving end of the internal rotor is connected to the central region, and the laser passes through the frosted glass at the edge region.

[0014] Its beneficial effect lies in the fact that by placing the connection point of the internal rotor in the central region of the frosted glass plate, the incident laser is allowed to pass through the edge region, thus achieving spatial decoupling between the drive structure and the optical path. This design avoids blocking the incident laser, allowing the laser to pass through a uniform scattering medium, further improving the stability of the brightness distribution during the measurement process.

[0015] In one embodiment, the internal rotor has an inner cavity extending through both ends; the laser beam passes through the frosted glass sheet and exits through the inner cavity of the internal rotor.

[0016] Its beneficial effect lies in utilizing the through-cavity of the internal rotor as a laser emission channel, thus achieving integrated optical path and drive structure. This design not only eliminates the need for additional openings or independent optical windows on the housing, effectively avoiding the risks of light leakage, stray light, and sealing failure caused by the splicing of multiple components, but also shortens the optical path transmission distance and reduces the energy loss of the beam during transmission.

[0017] In one embodiment, the housing has a removable flange located between the outer rotor and the inner rotor.

[0018] Its advantages lie in the modular and easily maintained sealing structure created by setting up a removable flange between the outer and inner rotors. This design not only provides a stable mounting reference for the magnetic coupling drive of the inner and outer rotors, which is conducive to maintaining the efficiency and coaxiality of magnetic field transmission, but also allows for quick inspection or replacement of components such as the frosted glass plate and the inner rotor without the need for complete disassembly, significantly reducing maintenance costs and downtime.

[0019] In one embodiment, the driving mechanism includes a transducer; the phase disturbance element is a mixing rod; the fixed end of the transducer is fixed to the inner wall of the housing; the first moving end of the transducer is fixedly connected to the mixing rod for driving the mixing rod to mechanically vibrate along the axial direction; when the laser passes through the mixing rod, the mechanical vibration of the mixing rod causes random changes in the optical path, thereby disrupting the spatial coherence of the laser.

[0020] Its beneficial effect is that by using a transducer to directly drive the axial vibration of the mixing rod, the random change in optical path caused by mechanical deformation is used to efficiently destroy the spatial coherence of the laser, thereby reducing the interference of interference fringes on the imaging quality from the source.

[0021] In one embodiment, the anti-interference phase disturbance module further includes an inertial counterweight unit; the transducer also has a second moving end, the second moving end and the first moving end being used to move simultaneously relative to the fixed end, and the directions of movement are opposite; the inertial counterweight unit is connected to the second moving end of the transducer, and the inertial counterweight unit, the transducer and the light mixing rod are coaxially arranged; when the transducer drives the light mixing rod to perform mechanical vibration along the axial direction, the inertial counterweight unit is used to generate a reverse mechanical vibration opposite in phase to the light mixing rod, so as to counteract the reaction force generated when the light mixing rod vibrates.

[0022] Its beneficial effect lies in the fact that by setting an inertial counterweight unit coaxial with the light mixing rod, and using the second moving end of the transducer to drive the counterweight unit to generate a reverse mechanical vibration opposite in phase to the light mixing rod, a self-balancing mechanical system can be formed inside the module. The inertial force generated by this reverse vibration is equal in magnitude and opposite in direction to the reaction force transmitted to the fixed end when the light mixing rod vibrates, thus achieving mutual cancellation of inertial forces at the source and reducing the vibration energy transmitted outward through the shell. This avoids displacement or loosening of surrounding precision optical components caused by the vibration of the anti-interference phase disturbance module itself, and also reduces fatigue damage caused by long-term stress on the shell, extending the service life of the anti-interference phase disturbance module.

[0023] In one embodiment, the mass of the inertial counterweight unit is equal to the mass of the light mixing rod.

[0024] Its beneficial effect lies in the fact that when the inertial counterweight unit and the light-mixing rod have equal mass, under the conditions that their amplitudes are the same and their directions of motion are opposite, the inertial forces generated by them can achieve equal and complete dynamic balance. This mass-matching design balances the canceling torque generated by the reverse vibration with the excitation torque of the light-mixing rod, weakening the net force and residual couple transmitted to the fixed end and the shell, and suppressing radial micro-flutter, pitch oscillation, and higher-order mode coupling induced by uneven force. As a result, the system not only achieves optimal vibration isolation performance and mechanical stability, but also avoids the risk of additional stress concentration or local resonance caused by counterweight mismatch, enabling the anti-interference phase disturbance module to maintain a pure axial vibration mode during long-term high-frequency operation, providing a highly reliable and repeatable physical basis for precision optical measurement.

[0025] In one embodiment, an annular gap is provided between the outer peripheral wall of the inertial counterweight unit and the inner wall of the housing.

[0026] Its beneficial effect lies in providing ample and contactless movement space for the counterweight unit to perform axial reverse mechanical vibration by setting an annular gap between the outer peripheral wall of the inertial counterweight unit and the inner wall of the shell, thus avoiding friction, collision, or jamming between the counterweight unit and the shell during high-frequency reciprocating motion. This annular gap not only ensures that the inertial counterweight unit can move freely strictly according to the preset trajectory, making the function of counteracting the reaction force of reverse vibration stable and reliable, but also prevents additional vibration and wear introduced by the collision between the outer peripheral wall of the inertial counterweight unit and the inner wall of the shell. At the same time, the annular gap also reserves space for the thermal expansion of the counterweight unit, preventing the inertial counterweight unit from contacting the inner wall of the shell due to thermal expansion during long-term operation, further improving the environmental adaptability and long-term operating accuracy of the anti-interference phase disturbance module under complex working conditions.

[0027] In one embodiment, the center of gravity of the inertial counterweight unit, the center of gravity of the light mixing rod, and the center of gravity of the shell are arranged collinearly, so that the reverse inertial force generated by the inertial counterweight unit and the vibration reaction force generated by the light mixing rod are on the same line of action, thereby reducing the rotational torque on the shell.

[0028] Its beneficial effect lies in the fact that by strictly arranging the centers of gravity of the inertial counterweight unit, the light-mixing rod, and the shell along the same line, the reverse inertial force and the vibration reaction force are not only equal in magnitude and opposite in direction, but also act precisely on the same axis, thereby weakening the parasitic rotational torque caused by the deviation of the force line. This coaxial force balance design effectively prevents harmful attitude disturbances such as torsion, swaying, or eccentric precession of the shell during high-frequency vibration, allowing the entire module to retain only pure axial translational degrees of freedom. In this embodiment, by arranging the centers of gravity of the inertial counterweight unit, the light-mixing rod, and the shell along the same line, the inertial forces of the inertial counterweight unit and the light-mixing rod are offset, and the rotational torque caused by non-collinear inertial forces is weakened, effectively preventing the shell from torturing or eccentrically moving during high-frequency vibration.

[0029] In one embodiment, the inertial counterweight unit includes a plurality of counterweight blocks; the plurality of counterweight blocks are spaced apart along the axial direction of the light mixing rod, so that the line of action of the resultant force of the reverse inertial force generated by the plurality of counterweight blocks coincides with the vibration axis of the light mixing rod, thereby omnidirectionally canceling the eccentric force in each radial direction.

[0030] Its beneficial effect lies in the fact that by designing the inertial counterweight unit as multiple counterweight blocks spaced along the axial direction, it is possible to provide precise torque compensation for the non-ideal mass distribution of the light-mixing rod caused by processing tolerances, material inhomogeneity, or assembly deviations. This distributed counterweight structure allows the resultant force line of the reverse inertial force to be precisely adjusted to completely coincide with the theoretical vibration axis of the light-mixing rod, thereby not only canceling the main vibration force in the axial direction, but also weakening the eccentric inertial force and accompanying alternating bending moment caused by the centroid shift in the radial section. As a result, the system effectively suppresses harmful dynamic behaviors such as transverse bending vibration, eddy current, and bearing off-center loading induced by unbalanced excitation, improves the transducer driving efficiency and vibration mode purity, and the light-mixing rod operates only in an ideal longitudinal standing wave mode across the entire frequency band, providing a highly symmetrical and radially disturbance-free stable mechanical environment for the anti-interference phase disturbance module.

[0031] In one embodiment, the anti-interference phase disturbance module further includes an optical window assembly; the optical window assembly is detachably connected to the housing; the optical window assembly includes a first optical window and a second optical window disposed opposite to each other, the first optical window and the second optical window being located on both sides of the phase disturbance element, and the laser sequentially passing through the first optical window, the phase disturbance element and the second optical window.

[0032] Its advantages lie in the fact that the dual-window detachable structure constructs an independent optical sealed chamber, effectively isolating the phase-scratching components from the external environment and improving the equipment's dustproof, moisture-proof, and pollution-resistant capabilities under complex operating conditions. The first and second optical windows are located on both sides of the scratching components, forming a complete optical path transmission channel. Furthermore, the detachable design enables rapid maintenance and replacement of core optical components without disassembling the entire housing, thus reducing maintenance costs.

[0033] In one embodiment, the anti-interference phase disturbance module further includes a water-cooling jacket; the side wall of the housing not connected to the optical window is connected to the water-cooling jacket; the water-cooling jacket is provided with water channels; the water channels contain cooling water; when the cooling water in the water channels flows, it is used to improve the heat dissipation efficiency of the housing.

[0034] Its beneficial effect lies in the integration of a water-cooling jacket into the non-optical window sidewall of the housing, creating a highly efficient closed-loop thermal management system. Through the circulating flow of cooling water, this design can quickly remove the Joule heat and mechanical friction heat generated by the high-speed vibration of the transducer and phase disturbance components, effectively preventing material thermal deformation, optical performance drift, or component fatigue failure caused by temperature rise, and thus enhancing the thermal stability of the equipment under long-term high-load operation.

[0035] In one embodiment, the anti-interference phase disturbance module further includes a purge gas path; the housing is provided with an inlet and an outlet; the purge gas path is connected to the housing through the inlet and the outlet, and is used to provide protective gas to the housing through the inlet and extract protective gas from the housing through the outlet.

[0036] Its beneficial effect is that by constructing a positive pressure protective barrier inside the housing through the purging gas path, the continuous flow of protective gas effectively isolates external dust, moisture and corrosive media from intrusion, eliminating the risk of optical component contamination and condensation from the source.

[0037] In one embodiment, the anti-interference phase disturbance module further includes a temperature detection unit; the temperature detection unit is used to detect the temperature of the optical window component in the anti-interference phase disturbance module and the temperature of the driving mechanism; when the temperature of the optical window component exceeds a first preset threshold, a first alarm signal is generated; the first alarm signal is used to control the flow rate of the cooling water to increase; when the temperature of the driving mechanism exceeds a second preset threshold, a second alarm signal is generated; the second alarm signal is used to control the movement speed of the driving mechanism to decrease; the second preset threshold is greater than or equal to the first preset threshold.

[0038] Its beneficial effects lie in achieving refined thermal management of the optical window and drive mechanism through dual-channel independent temperature monitoring and closed-loop feedback control. When the temperature of the optical window assembly exceeds a first preset threshold, the system automatically increases the cooling water flow to prevent optical path distortion or coating damage caused by thermal deformation of the window; when the temperature of the drive mechanism exceeds a second preset threshold, the system controls the movement speed of the drive mechanism to decrease, thus preventing the motor in the drive mechanism from overheating and burning out. The above threshold settings meet the heat dissipation requirements of the optical window assembly and drive mechanism, avoid local overheating, and help improve the system's response speed and operational safety.

[0039] According to a second aspect of the present invention, a wafer warpage measurement system is provided. The system includes a laser, a beam expander group, a beam splitter, a focusing lens, an imaging detection unit, a processing unit, and an anti-interference phase disturbance module as described in the first aspect. The anti-interference phase disturbance module is disposed between the beam expander group and the beam splitter. The laser is used to emit a laser beam. The beam expander group is used to collimate the laser beam emitted by the laser and expand the beam diameter to cover the effective aperture of the anti-interference phase disturbance module. The beam splitter is used to split the beam output by the anti-interference phase disturbance module into two parallel beams, a first beam and a second beam. The focusing lens is used to converge the first beam and the second beam onto the surface of the wafer, forming two light spots. The imaging detection unit is used to receive reflected light from the surface to obtain a light spot position image containing the two light spots. The processing unit is used to measure the warpage of the wafer based on the light spot position image.

[0040] Its beneficial effect lies in the fact that the anti-interference phase disturbance module suppresses interference noise at the spot, making the dual-spot image clear and stable, and avoiding spot positioning failure or data interruption caused by fringe flicker. Integrating the anti-interference module between the beam expander and beam splitter can improve the system's anti-interference capability without changing the core optical path architecture of the traditional two-point method.

[0041] In one embodiment, the processing unit is electrically connected to the drive mechanism of the anti-interference phase disturbance module; the processing unit is used to obtain a dynamic interference contrast V(ω) based on the spot position image, the dynamic interference contrast V(ω) being used to represent the visibility of dynamic interference fringes when the spot moves; and to control the movement speed of the drive mechanism based on the dynamic interference contrast.

[0042] Its beneficial effect is that by calculating the dynamic interference contrast in real time, the movement speed of the drive mechanism can be automatically adjusted, which can adaptively reduce the phenomenon of coherence recovery.

[0043] In one embodiment, the phase disturbance element in the anti-interference phase disturbance module is a frosted glass plate, and the driving mechanism includes an internal rotor; the dynamic interference contrast V(ω) and the rotational angular velocity ω of the frosted glass plate driven by the internal rotor satisfy the following relationship: V(ω)≤V0·sinc(ω·Δt·d / Λ); Where Δt is the exposure time of the spot position image, d is the spot diameter in the spot position image, Λ is the spatial coherence length of the surface scattering structure of the frosted glass sheet, V0 is the static interference contrast, and sinc is the sampling function.

[0044] Its beneficial effect is that by setting the mathematical relationship between the dynamic interference contrast V(ω) and the rotational angular velocity ω of the internal rotor driving the frosted glass sheet, the rotational speed that meets the contrast suppression requirement can be inverted in real time, effectively compensating for the rotational speed fluctuation caused by mechanical wear, and dynamically suppressing the reproduction of interference fringes during long-term operation.

[0045] This invention fundamentally solves the problem of interference fringe flicker caused by laser coherence by introducing an anti-interference phase disturbance module. Utilizing a phase disturbance element driven by a driving mechanism, the spatial coherence of the incident laser is rapidly altered, converting the highly coherent laser into an incoherent or low-coherence light source. This dynamic modulation at the hardware level averages the bright and dark fringes in the interference pattern over time, reducing the drastic fluctuations in local brightness caused by minute variations in optical path difference. This ensures that the two reflected light spots maintain a stable brightness distribution throughout the measurement process. This core mechanism prevents interruptions in wafer warpage calculations due to discontinuous brightness distribution, thus improving the continuity and reliability of the measurement.

[0046] In terms of structural design and driving method, this invention provides a variety of optimization schemes to improve system stability and maintenance convenience. For example, the magnetic coupling of the external rotor and the internal rotor drives the non-contact rotating frosted glass plate, reducing friction, gaps, and micro-vibrations caused by mechanical transmission, which is beneficial to the stability of the optical path system. At the same time, by setting the driving connection point in the central region of the frosted glass, the laser passes through the edge region, realizing spatial decoupling between the driving structure and the optical path, and avoiding laser obstruction. In addition, using the internal rotor through the inner cavity as the laser emission channel and setting a detachable flange not only realizes the integrated integration of the optical path and the driving structure, reducing the risk of light leakage and stray light, but also constructs a modular and easy-to-maintain sealed architecture, reducing downtime maintenance costs.

[0047] To address environmental adaptability and thermal management under complex operating conditions, this invention integrates multiple protection and control mechanisms. A magnetic circuit isolation barrier is constructed through a non-magnetic shell and gap design, ensuring efficient magnetic force transmission while blocking magnetic field interference to surrounding electronic components. Simultaneously, the integration of a water-cooling jacket, purge air path, and dual optical window assembly creates a dustproof, moisture-proof, and contamination-resistant closed-loop thermal management system, effectively preventing optical components from deforming due to temperature rise or failing due to contamination. Combined with closed-loop feedback control from the temperature detection unit, the system can automatically adjust the cooling water flow or reduce the drive speed based on the real-time temperature of the optical window and drive mechanism, achieving refined thermal management and contributing to the thermal stability and safety of the equipment under prolonged high-load operation.

[0048] Finally, this invention achieves intelligent linkage and adaptive control between the measurement system and the anti-interference module. The processing unit can obtain the dynamic interference contrast in real time based on the spot position image, and use this to control the movement speed of the drive mechanism, forming a closed-loop feedback. In particular, a mathematical model between dynamic interference contrast and rotation speed is established, enabling the system to invert the optimal rotation speed that meets the contrast suppression requirements in real time, effectively compensating for speed fluctuations caused by mechanical wear. This adaptive adjustment strategy helps reduce coherence recovery phenomena and avoids the recurrence of dynamic interference fringes during long-term operation, further improving the accuracy and robustness of the wafer warp measurement system. Attached Figure Description

[0049] Figure 1 This is a schematic diagram illustrating the structure of an anti-interference phase disturbance module according to an exemplary embodiment.

[0050] Figure 2 This is a schematic diagram illustrating an installation structure of a frosted glass sheet, an inner rotor, and an outer rotor according to an exemplary embodiment.

[0051] Figure 3 This is a partial cross-sectional example diagram illustrating an anti-interference phase disturbance module according to an exemplary embodiment.

[0052] Figure 4 This is a schematic diagram of the installation structure of a light mixing rod and a transducer according to an exemplary embodiment.

[0053] Figure 5 This is a schematic diagram of a wafer warp measurement system according to an exemplary embodiment.

[0054] Figure 6 This is an example diagram illustrating the spot position obtained by a wafer warp measurement system without an anti-interference phase disturbance module, according to an exemplary embodiment.

[0055] Figure 7This is an example diagram illustrating the position of a spot obtained by a wafer warp measurement system equipped with an anti-interference phase disturbance module, according to another exemplary embodiment.

[0056] Figure 8 This is a schematic diagram illustrating the curve of interference contrast as a function of rotational speed, according to an exemplary embodiment.

[0057] Explanation of the reference numerals in the figure: 1. Housing; 2. Phase scrambling element; 3. Drive mechanism; 4. Anti-interference phase scrambling module; 5. Optical window assembly; 11. Laser; 12. Beam expander assembly; 13. Focusing lens; 14. Imaging detection unit; 15. Imaging lens; 16. Epitaxial wafer; 17. CMOS camera; 18. Reaction chamber; 19. Camera lens; 20. Beam splitter; 21. Frosted glass plate; 211. Edge region; 212. Central region; 22. Light mixing rod; 31. Internal rotor; 311. Fixed end; 312. Moving end; 3121. First moving end; 32. External rotor; 33. Flange; 34. Transducer; 35. External motor; 41. Incident laser beam; 42. Rotation axis; 43. Axial axis; 51. First optical window; 52. Second optical window. Detailed Implementation

[0058] Unless otherwise defined, the technical or scientific terms used in this specification and claims shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. Specific embodiments of the invention will be described below with reference to the accompanying drawings. It should be noted that, in order to provide a concise description, this specification cannot provide a detailed description of all features of the actual embodiments. Without departing from the spirit and scope of the invention, those skilled in the art can make modifications and substitutions to the embodiments of the invention, and the resulting embodiments are also within the protection scope of the invention.

[0059] To address the aforementioned technical problems, this invention proposes an anti-interference phase disturbance module and a wafer warpage measurement system, which can maintain a stable brightness distribution of the light spot during the measurement process to improve the continuity of wafer warpage calculation.

[0060] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0061] like Figure 1 , Figure 2 and Figure 3As shown, the first embodiment of the present invention provides an anti-interference phase disturbance module 4 for weakening laser coherence during wafer warpage measurement. The anti-interference phase disturbance module 4 includes a housing 1, a phase disturbance element 2, and a driving mechanism 3. The phase disturbance element 2 and the driving mechanism 3 are both located within the housing 1. The driving mechanism 3 has a fixed end 311 and a moving end 312. The fixed end 311 is connected to the housing 1. The moving end 312 is connected to the phase disturbance element 2. When the driving mechanism 3 is activated, the moving end 312 moves relative to the fixed end 311 to drive the phase disturbance element 2 to perform mechanical movement. The phase disturbance element 2 is located in the laser optical path for measuring the wafer warpage. During mechanical movement, the phase disturbance element 2 is used to disrupt the spatial coherence of the incident laser to obtain the emitted laser. The emitted laser is used to irradiate the surface of the wafer to measure the wafer warpage.

[0062] In some specific embodiments, a sealed housing 1 is used as the core protective unit of the anti-interference device. 316L stainless steel or Hastelloy C-276 with excellent corrosion resistance is used as the base material. Its outer surface is electrolytically polished to reduce the risk of nanoparticle adhesion and facilitate cleaning and maintenance.

[0063] In some examples, the housing 1 is designed as a rectangular cuboid structure with a length of 120mm, a width of 80mm, and a height of 60mm. The effective internal cavity dimensions are 100mm × 60mm × 40mm, and the wall thickness is set to 3mm. This ensures that the housing 1 has sufficient mechanical rigidity in the vacuum environment of the MOCVD reaction chamber to resist external pressure fluctuations. Regarding sealing performance, the housing 1 meets vacuum-level standards, with a static leakage rate of less than 1×10⁻⁶. -9 Pa•m 3 All flange connections have abandoned traditional rubber parts, replacing them with oxygen-free copper or silver-plated stainless steel gaskets for hard sealing, thereby reducing the risk of aging and volatile pollution at high temperatures. Furthermore, the internal cavity of shell 1 is designed as an independent, airtight space, isolated from the main atmosphere of the MOCVD reaction chamber, and equipped with an inert gas, such as N2. 2 Alternatively, an Ar purge interface can be used to maintain the pressure inside the cavity slightly higher than the pressure in the reaction chamber, for example, 50 mbar higher, to form a positive pressure barrier, effectively preventing corrosive reactive gases such as NH3 or TMGa from back-diffusing into the optical element area, thus enabling the phase disturbance module to operate stably for a long time under extreme conditions.

[0064] In one embodiment, the anti-interference phase disturbance module 4 further includes an external rotor 32; the external rotor 32 is located on the outside of the housing 1; the driving mechanism 3 is an internal rotor 31; the fixed end 311 of the internal rotor 31 is connected to the inner wall of the housing 1; the moving end 312 of the internal rotor 31 is rotatably connected to the fixed end 311; the external rotor 32 and the internal rotor 31 are coaxially arranged, and the external rotor 32 acts on the moving end 312 of the internal rotor 31 through magnetic force; the moving end 312 is rotatably connected to the fixed end 311; when the external rotor 32 rotates, it drives the moving end 312 of the internal rotor 31 to rotate around the fixed end 311; the phase disturbance element 2 is a frosted glass plate 21; the position where the internal rotor 31 is fixedly connected to the frosted glass plate 21 does not overlap with the position where the laser passes through the frosted glass.

[0065] In some specific embodiments, the phase disrupting element 2 is a frosted glass sheet 21, the substrate of which is JGS1 grade fused silica. This material has a transmittance of over 92% at a wavelength of 635 nm and a density of 0.55 × 10⁻⁶. -6 With a low coefficient of thermal expansion of / K, it can withstand ambient temperatures up to 1200℃, and the actual operating temperature rise is controlled within 60℃, which is beneficial to improving the dimensional stability of the phase disturbance element 2 in the external optical path of the high-temperature reaction chamber. The surface of the frosted glass plate 21 is precision-treated on one or both sides, such as by sandblasting or hydrofluoric acid etching, to form a randomly distributed micro-uneven structure with a roughness Ra controlled within the range of 0.8 to 1.5μm and a feature size of approximately 1 to 10μm, which is much larger than the incident laser wavelength, thus effectively destroying the coherence of the light. The rotating frosted glass plate 21 is generally disc-shaped with a diameter of Φ25mm and a thickness of 2.0±0.05mm, and the edges are chamfered by 0.3mm to prevent edge chipping. In terms of fixing method, any organic adhesives are abandoned, and instead a glue-free mechanical clamping scheme is adopted. A precision-machined pressure ring and an elastic gasket are used to firmly press the frosted glass plate 21 onto the flange surface at the end of the rotating shaft 42, which helps to reduce the risk of adhesive aging, carbonization, or volatilization contaminating the optical system at high temperatures. The drive system supports speed adjustment from 100rpm to 1200rpm, with a typical operating point set at 600rpm, corresponding to a 10Hz rotation frequency. By dynamically introducing random spatial phase perturbations, it achieves rapid spatiotemporal averaging and blanking of interference fringes, thereby improving the signal-to-noise ratio of the light spot and measurement continuity.

[0066] In one embodiment, a gap is provided between the external rotor 32 and the outer wall of the housing 1; the housing 1 is made of a non-magnetic material.

[0067] In some specific embodiments, the contactless drive mechanism 3 uses a magnetic coupler as the core transmission solution, aiming to solve the leakage and particulate contamination problems caused by traditional dynamic seals. This mechanism consists of an inner rotor 31, an outer rotor 32, and an isolation sleeve. The inner rotor 31 is fixed to a frosted glass shaft 42 and is made of high-temperature resistant samarium cobalt (SmCo) permanent magnets, with a magnetic energy product (BH). max The magnet has a 24MGOe rating and an operating temperature up to 300℃. The magnet is designed as a ring structure with an outer diameter of 20 mm, an inner diameter of 10 mm, and a thickness of 8 mm. It features four pairs of alternating N and S magnetic poles and is encapsulated in a non-magnetic stainless steel sleeve to prevent corrosion. The outer rotor 32, also composed of samarium cobalt magnets, is mounted on the spindle of the outer motor 35 and is coaxially opposite to the inner rotor 31. The two are physically separated by a titanium alloy TC4 isolation sleeve with a thickness reduced to 0.8 to 1.0 mm. The wall thickness of this area, including the air gap, is controlled within the range of 3 to 5 mm, and the isolation sleeve area can be designed as an independent flange for easy maintenance. The external drive uses a stepper motor with an encoder or a brushless DC motor with a power of 10 watts and an adjustable speed from 0 to 2000 rpm, providing an output torque of 0.2 Nm to ensure a safety factor greater than two. The magnetic coupler possesses excellent transmission characteristics, with a maximum transmitted torque of 0.5 Nm, sufficient to overcome the rotational inertia of the frosted glass plate 21 and the rotating shaft 42. It supports a wide speed range of 0 to 1500 rpm, allowing for ±1 mm axial offset and ±2° angular deviation, with a service life exceeding 20,000 hours and no contact wear. Compared to traditional dynamic sealing solutions, this embodiment uses a magnetic coupler, which helps reduce friction, decrease particle generation, and reduce lubrication requirements. The fully enclosed structure with a non-magnetic stainless steel sleeve can withstand the high temperature and corrosive environment surrounding the reaction chamber. In some specific embodiments, the internal rotor 31 uses neodymium iron boron magnets.

[0068] In one embodiment, the frosted glass sheet 21 has an edge region 211 and a central region 212; the moving end 312 of the internal rotor 31 is connected to the central region 212, and the laser passes through the frosted glass at the edge region 211.

[0069] In some specific embodiments, to address the problem of the rotating shaft 42 obstructing the optical path in traditional coaxial driving schemes, an eccentric driving optical path unobstructed design is adopted. Specifically, the fixed end 311 of the frosted glass rotating shaft 42 is fixedly connected to the central region 212 of the frosted glass sheet 21, aligning the optical path transmission path with the edge region 211 of the frosted glass sheet 21. Through this spatially separated layout, the incident laser beam 41 only passes through the central light-transmitting area of ​​the frosted glass sheet 21 that is not occupied by the mechanical structure, while the rotating shaft 42 and its supporting structure are completely located on the edge side outside the beam range. This design eliminates the physical obstruction of the main optical path by the rotating shaft 42, keeping the light spot intact on the frosted glass surface, while avoiding light intensity distribution distortion or diffraction effects caused by obstruction, thus improving the modulation efficiency of the phase-disrupting element 2 and the overall performance of the optical system.

[0070] In one embodiment, the internal rotor 31 has an inner cavity extending through both ends; the laser beam passes through the frosted glass sheet 21 and exits through the inner cavity of the internal rotor 31.

[0071] In some specific embodiments, the internal rotor 31 adopts a hollow structure design, with an axial cavity that runs through both ends. This cavity serves as a channel for laser transmission and is precisely coaxially aligned with the optical path of the frosted glass plate 21. In specific implementation, after the incident laser beam 41 passes through the rotating frosted glass plate 21, it exits directly through the central cavity of the internal rotor 31 without the need to open holes or perform avoidance treatment on the magnet assembly or the rotating shaft 42.

[0072] In some examples, the drive mechanism 3 uses a high-precision stepper motor or a brushless DC motor as its power source. This motor has a built-in high-resolution encoder to provide real-time feedback on speed and position information, enabling closed-loop control. Its rated power is set at 10W, and its speed adjustment range covers 0 to 2000 rpm, flexibly adapting to the precise speed requirements of different process stages. Regarding torque output, the motor is designed to deliver a maximum output torque of 0.2 N•m, with a safety margin of more than twice the rated torque. This ensures that even under the high-temperature environment of up to 150°C and vacuum conditions inside the MOCVD reaction chamber, and even if there are fluctuations in frictional resistance or sudden load changes in the housing 1, the internal rotor 31 can still be driven stably and reliably, effectively avoiding step loss or stalling, and guaranteeing the long-term continuous operation of the optical path modulation system.

[0073] In one embodiment, the housing 1 has a removable flange 33 located between the outer rotor 32 and the inner rotor 31.

[0074] In some specific embodiments, the flange portion 33 has a wall thickness of 0.8 to 1.0 mm to reduce leakage magnetic loss and improve torque transmission efficiency; the flange portion 33 is made of titanium alloy TC4, which utilizes its excellent non-magnetic, high strength and corrosion resistance properties to enable the flange portion 33 to work stably for a long time in the high temperature and highly corrosive MOCVD reaction environment without interfering with the magnetic field distribution.

[0075] In one embodiment, the driving mechanism 3 includes a transducer 34; the phase disturbance element 2 is a mixing rod; the fixed end 311 of the transducer 34 is fixed to the inner wall of the housing 1; the moving end 312 of the transducer 34 is specifically a first moving end 3121; the first moving end 3121 of the transducer 34 is fixedly connected to the mixing rod 22 and is used to drive the mixing rod 22 to mechanically vibrate along the axial direction 43; when the laser passes through the mixing rod 22, the mechanical vibration of the mixing rod 22 causes random changes in the optical path, thereby destroying the spatial coherence of the laser.

[0076] like Figure 4 As shown in some specific embodiments, the beam mixing rod 22 is a fused silica rod 60 mm long and 8 mm in diameter. Its two ends are highly polished to ensure beam transmission quality, while the sides are uniformly roughened to enhance scattering. One end of the quartz rod is rigidly bonded to the end face of a piezoelectric ceramic ultrasonic transducer on a sealing flange using high-temperature resistant epoxy resin. This transducer operates at a frequency of 40 kHz, has a rated power of 10 W, and is equipped with a dedicated ultrasonic drive power supply with an adjustable output range of 0 to 100%. During operation, the drive power supply excites the transducer to generate axial mechanical vibration, causing the quartz rod to reciprocate at a high frequency of 40 kHz with an amplitude of approximately 1 to 5 micrometers. When the incident laser beam 41 passes through this high-speed vibrating medium, the optical path difference is randomly modulated due to the rapid deformation of the rod. The modulation depth can reach several wavelengths, and after time averaging, the contrast of the interference fringes is reduced, thereby achieving efficient beam homogenization. Compared to the rotary solution, this embodiment uses a transducer and a light mixing rod, avoiding the use of rotating inertial components, eliminating the need for a rotating through shaft and a rotating dynamic seal, allowing the sealed housing with the optical window to maintain a protective atmosphere for a long time, thus improving the sealing reliability.

[0077] In one embodiment, the anti-interference phase disturbance module further includes an inertial counterweight unit; the moving end 312 of the transducer 34 is specifically a first moving end 3121 and a second moving end, the second moving end and the first moving end 3121 are used to move simultaneously relative to the fixed end, and the directions of movement are opposite; the inertial counterweight unit is connected to the second moving end of the transducer 34, and the inertial counterweight unit, the transducer 34 and the light mixing rod 22 are coaxially arranged; when the transducer 34 drives the light mixing rod 22 to perform mechanical vibration along the axial direction 43, the inertial counterweight unit is used to generate a reverse mechanical vibration opposite to the phase of the light mixing rod 22, so as to counteract the reaction force generated when the light mixing rod 22 vibrates.

[0078] In some specific embodiments, the mass of the inertial counterweight unit is precisely configured to be equal to the equivalent vibrational mass of the light mixing rod 22, and the installation positions of the two relative to the fixed end of the transducer 34 satisfy the torque balance condition, so that the reverse inertial force and the vibration reaction force of the light mixing rod 22 at any operating frequency not only match in amplitude and are out of phase, but also that the line of action of the resultant force always passes through the center of mass of the system. At the same time, the first moving end 3121 and the second moving end of the transducer 34 adopt a symmetrical elastic support structure, so that the first moving end 3121 and the second moving end naturally exhibit a reciprocating displacement with a 180° phase difference under the excitation of the driving signal, and can achieve inherent dynamic self-balancing without the need for an additional control loop. In addition, the inertial counterweight unit and the light mixing rod 22 can be constrained within the housing 1 by a coaxial guide mechanism, limiting them to retain only the axial degree of freedom 43. By matching the mass of the inertial counterweight unit and the light mixing rod, and by using 180° opposite phase drive for the first moving end 3121 and the second moving end, the inertial forces generated by the system at any operating frequency can cancel each other out inside the housing, thereby reducing the transmission of vibration to the outside of the housing.

[0079] It is worth noting that by setting an inertial counterweight unit coaxial with the light mixing rod 22, and using the second moving end of the transducer 34 to drive the counterweight unit to generate a reverse mechanical vibration opposite in phase to the light mixing rod 22, a self-balancing mechanical system can be formed inside the module. The inertial force generated by this reverse vibration is equal in magnitude and opposite in direction to the reaction force transmitted to the fixed end when the light mixing rod 22 vibrates, thus achieving mutual cancellation of inertial forces at the source and reducing the vibration energy transmitted outward through the housing 1. This avoids displacement or loosening of surrounding precision optical components caused by the vibration of the anti-interference phase disturbance module itself, and also reduces fatigue damage caused by long-term stress on the housing, extending the service life of the anti-interference phase disturbance module.

[0080] In one embodiment, the mass of the inertial counterweight unit is equal to the mass of the light mixing rod 22.

[0081] In some specific embodiments, the mass of the inertial counterweight unit is not simply equal to the static total mass of the light mixing rod 22, but rather precisely matches the equivalent vibrational mass of the light mixing rod 22 under a specific operating mode. This equivalent mass is obtained through finite element simulation or experimental modal analysis, taking into account factors such as the internal stress distribution of the light mixing rod 22, boundary constraint stiffness, and the coupling effect of the transducer 34. Simultaneously, to compensate for mass mismatch caused by manufacturing tolerances and assembly deviations, the inertial counterweight unit is also equipped with a finely adjustable counterweight adjustment mechanism, such as threaded counterweight screws or replaceable shim sets, allowing for precise calibration of the reverse inertial force amplitude after assembly, ensuring that the residual transmitted force at the operating frequency point is below a preset threshold. Furthermore, when the system needs to switch between multiple discrete frequency points, the inertial counterweight unit can adopt a segmented or variable inertia structure, enabling the equivalent mass to adaptively adjust with the driving frequency, thereby maintaining high-precision dynamic force balance under different operating conditions.

[0082] It is worth noting that when the inertial counterweight unit and the light-mixing rod 22 have equal mass, under the conditions that their amplitudes are the same and their directions of motion are opposite, the inertial forces they generate can achieve equal and complete dynamic balance. This mass matching design balances the canceling torque generated by the reverse vibration with the excitation torque of the light-mixing rod 22, weakening the net force and residual couple transmitted to the fixed end and the housing 1, and suppressing radial micro-flutter, pitch oscillation, and higher-order mode coupling induced by uneven force. As a result, the system not only achieves optimal vibration isolation performance and mechanical stability, but also avoids the risk of additional stress concentration or local resonance caused by counterweight mismatch, ensuring that the anti-interference phase disturbance module maintains pure axial vibration during long-term high-frequency operation.

[0083] In one embodiment, an annular gap is provided between the outer peripheral wall of the inertial counterweight unit and the inner wall of the housing 1.

[0084] In some specific embodiments, the radial dimension of the annular gap is strictly controlled between 0.05 mm and 0.2 mm, which is sufficient to accommodate the slight radial sway and thermal expansion deformation of the inertial counterweight unit under high-frequency vibration, while avoiding the introduction of additional nonlinear collision or airflow disturbance noise due to excessive gap. Simultaneously, the annular gap can be filled with a low-viscosity damping fluid or fitted with a flexible sealing ring to provide appropriate radial damping, suppressing the lateral resonance modes that may occur in the counterweight unit in non-operating frequency bands, and preventing it from generating stray vibration transmission paths due to contact friction with the housing 1. Furthermore, the corresponding surfaces of the inner wall of the housing 1 and the outer peripheral wall of the inertial counterweight unit are precision ground and polished, and coated with a wear-resistant and friction-reducing coating. Even when the gap narrows locally due to assembly errors or material creep during long-term operation, it can still maintain a contactless and low-wear free motion state, ensuring that the reverse inertial force is always transmitted along the ideal axial direction 43, without degenerating into a disturbance force containing rotational components due to radial interference, further improving the dynamic consistency of the anti-interference phase disturbance module throughout its entire life cycle.

[0085] It is worth noting that by setting an annular gap between the outer peripheral wall of the inertial counterweight unit and the inner wall of the housing 1, sufficient and contactless movement space is provided for the counterweight unit to perform reverse mechanical vibration, effectively avoiding friction, collision, or jamming between the counterweight unit and the inner wall of the housing 1 during high-frequency reciprocating motion. This annular gap not only ensures that the inertial counterweight unit can move freely strictly according to the preset trajectory, making the function of counteracting the reaction force of reverse vibration stable and reliable, but also prevents additional vibration and wear caused by the collision between the outer peripheral wall of the inertial counterweight unit and the inner wall of the housing. At the same time, the annular gap also reserves space for the thermal expansion of the counterweight unit, preventing the inertial counterweight unit from contacting the inner wall of the housing due to thermal expansion during long-term operation.

[0086] In one embodiment, the center of gravity of the inertial counterweight unit, the center of gravity of the light mixing rod 22, and the center of gravity of the housing 1 are arranged collinearly, so that the reverse inertial force generated by the inertial counterweight unit and the vibration reaction force generated by the light mixing rod 22 are on the same line of action, thereby reducing the rotational torque on the housing 1.

[0087] In some specific embodiments, to ensure that the three centers of gravity are strictly collinear, a laser alignment instrument or a high-precision dynamic balancing testing system is used during the assembly stage to detect and fine-tune the coaxiality of the inertial counterweight unit, the light mixing rod 22, and the housing 1. This is achieved by setting eccentric adjustment screws on the end face of the counterweight unit or embedding self-aligning shims at the mounting flange of the housing 1 to compensate for the center-of-gravity shift caused by the accumulation of machining tolerances in each component. Simultaneously, both the light mixing rod 22 and the inertial counterweight unit adopt a rotationally symmetrical structural design about their own geometric axes and are made of materials with uniform density and low internal friction (such as titanium alloy or silicon carbide) to reduce the risk of center-of-gravity deviation from the outset. In addition, the housing 1 is equipped with an axial 43 guide keyway or flexible diaphragm support structure, which restricts the inertial counterweight unit to translate only along the axial 43, and constrains its radial displacement and angular rotational degrees of freedom. Thus, even under long-term vibration fatigue or temperature alternation conditions, the three centers of gravity can still be kept collinear, so that the reverse inertial force and the vibration reaction force always form a pair of pure axial 43 balanced force couples, without generating any residual torque around the center of mass of the housing 1. This effectively avoids torsional vibration or attitude drift of the housing 1, and provides a highly stable mechanical reference for the entire anti-interference phase disturbance module.

[0088] It is worth noting that by strictly arranging the centers of gravity of the inertial counterweight unit, the light-mixing rod 22, and the shell 1 collinearly, the reverse inertial force and the vibration reaction force are not only equal in magnitude and opposite in direction, but also act precisely on the same axis, thereby weakening the parasitic rotational torque caused by the deviation of the force line. This coaxial force balance design effectively prevents harmful attitude disturbances such as torsion, swaying, or eccentric precession of the shell 1 during high-frequency vibration, allowing the entire module to retain only a pure axial translational degree of freedom of 43 degrees. In this embodiment, by arranging the centers of gravity of the inertial counterweight unit, the light-mixing rod 22, and the shell 1 collinearly, the inertial forces of the inertial counterweight unit and the light-mixing rod 22 are counteracted, and the rotational torque caused by non-collinear inertial forces is weakened, preventing the shell from torturing or eccentrically moving during high-frequency vibration.

[0089] In one embodiment, the inertial counterweight unit includes a plurality of counterweight blocks; the plurality of counterweight blocks are spaced apart along the axial direction 43 of the light mixing rod 22, so that the line of action of the resultant force of the reverse inertial force generated by the plurality of counterweight blocks coincides with the vibration axis of the light mixing rod 22, thereby omnidirectionally canceling the eccentric force in each radial direction.

[0090] In some specific embodiments, the spacing and mass distribution of the multiple counterweights along the axial direction 43 are not uniformly arranged, but optimized according to the mode shape function of the mixing rod 22 in the working mode, so that the sum of the local inertial moments generated by each counterweight is zero, thereby ensuring that the line of action of the resultant force precisely passes through the vibration node or equivalent center of mass of the mixing rod 22. Each counterweight is equipped with an independent radial fine-tuning mechanism, such as circumferentially distributed set screws or eccentric bushings, which allows for sub-millimeter-level correction of the center of mass position of a single counterweight after assembly to compensate for local eccentricity caused by manufacturing and installation errors. At the same time, adjacent counterweights are coupled through flexible connectors or elastic vibration isolation pads, which maintains the overall axial stiffness 43 to ensure synchronous reverse movement and absorbs high-frequency harmonic components to prevent internal shear forces from being generated between counterweights due to phase lag. In addition, the outer contours of all counterweights adopt a streamlined or chamfered design and maintain a constant annular gap with the inner wall of the housing 1. This embodiment combines a streamlined outer contour design with an annular gap to reduce the air damping of the counterweight, thereby making the counterweight unit stable in reciprocating motion.

[0091] It is worth noting that by designing the inertial counterweight unit as multiple counterweights spaced along the axial direction 43, precise torque compensation can be achieved for the non-ideal mass distribution of the light mixing rod 22 caused by machining tolerances, material inhomogeneity, or assembly deviations. This distributed counterweight structure allows the resultant force line of the reverse inertial force to be precisely adjusted to completely coincide with the theoretical vibration axis of the light mixing rod 22. This not only cancels the main vibration force along the axial direction 43 but also weakens the eccentric inertial force and accompanying alternating bending moment caused by the center of mass shift in any radial section. As a result, the system effectively suppresses harmful dynamic behaviors such as transverse bending vibration, eddy current, and bearing off-center loading induced by unbalanced excitation, improves the driving efficiency and vibration mode purity of the transducer 34, and ensures that the light mixing rod 22 operates only in an ideal longitudinal standing wave mode across the entire frequency band, providing a highly symmetrical and radially disturbance-free stable mechanical environment for the anti-interference phase disturbance module.

[0092] In some possible embodiments, the dynamic matching between the inertial counterweight unit and the light mixing rod 22 not only relies on equal static mass and collinear center of gravity, but also further introduces an active compensation mechanism based on real-time feedback. Specifically, a micro-accelerometer array is integrated inside the housing 1, arranged at multiple points along the axial direction 43 and radial direction, for real-time monitoring of the actual vibration response of the light mixing rod 22 and the inertial counterweight unit; the controller, based on the signals collected by the sensors, uses an adaptive filtering algorithm to identify online the mass mismatch and center of gravity offset caused by temperature drift, material aging, or assembly stress relaxation at the current operating frequency, and drives the piezoelectric micro-displacement actuator or electromagnetic adjustment coil built into the inertial counterweight unit to dynamically adjust the equivalent mass distribution or axial position of the counterweight block at the micrometer level, so that the reverse inertial force always maintains equal amplitude, opposite phase, and coincident line of action with the instantaneous vibration reaction force of the light mixing rod 22. Meanwhile, to improve the system's adaptability over a wide frequency band, the inertial counterweight unit adopts a segmented variable inertia structure, with each segment connected by a magnetorheological elastomer. Its stiffness and damping characteristics can be continuously adjusted by an external magnetic field, thereby automatically changing the overall equivalent mass and modal frequency under different driving frequencies.

[0093] It is worth noting that the vibration reduction performance of traditional fixed counterweights relies on the matching natural frequencies and excitation frequencies of the system. Since the mass, stiffness, and damping of a fixed counterweight are constant, its effective operating frequency band is narrow, achieving ideal counterforce cancellation only within a small range near the design frequency. Once the driving frequency fluctuates or deviates from the preset resonance point, the motion phase and amplitude of the counterweight unit change drastically, leading to a sharp decrease in vibration reduction effect or even amplification of vibration. In contrast, the segmented variable inertia structure combined with magnetorheological elastomer connections used in this embodiment overcomes this limitation. By continuously adjusting the stiffness and damping of the connectors through an external magnetic field, the system can dynamically change the equivalent mass and modal frequency, enabling the counterweight unit to have adaptive tracking capabilities. This means that regardless of how the operating frequency of the light mixing rod fluctuates, the counterweight unit can automatically adjust its dynamic characteristics to maintain the vibration phase relationship and vibration amplitude ratio, thereby maintaining stable vibration reduction performance over a wider frequency band and solving the drawbacks of narrow frequency band and poor adaptability of traditional passive counterweight units.

[0094] In a typical application scenario, this anti-interference phase disturbance module is integrated into the core scanning unit of a high-precision wafer warp optical measurement system to reduce the micro-vibration interference introduced to the precision optical platform and displacement sensor during the reciprocating motion of the beam mixer 22. Specifically, during wafer surface topography inspection, the beam mixer 22 needs to oscillate rapidly along the axial direction 43 at a frequency of several hundred hertz to achieve beam modulation. Without effective vibration suppression measures, the periodic reaction force generated will be transmitted to the optical support through the housing 1, causing sub-nanometer jitter in the reference optical path of the laser interferometer or confocal sensor, severely degrading the repeatability and resolution of warp measurement. With the structure described in this embodiment, the inertial counterweight unit and the beam mixer 22 constitute a self-balancing dynamic system, which not only cancels the axial direction 43 vibration at its source, but also eliminates the residual torque that may induce angular vibration of optical components through the collinear design of the three centers of gravity and the radially symmetrical layout of the multiple counterweights. In actual production line verification, the measurement system equipped with this module reduced the platform vibration amplitude by more than 98% compared with the traditional single-actuator solution at a scanning speed of 200mm / s. The repeatability accuracy (3σ) of wafer warpage measurement was optimized from the original 15nm to within 2nm. Moreover, under the harsh conditions of continuous operation for 72 hours and ambient temperature fluctuation of ±2℃, the drift of the measurement result was less than 0.5nm, which meets the stability requirements of advanced process nodes for online detection of wafer geometric parameters.

[0095] In one embodiment, the anti-interference phase disturbance module 4 further includes an optical window assembly 5; the optical window assembly 5 is detachably connected to the housing 1; the optical window assembly 5 includes a first optical window 51 and a second optical window 52 disposed opposite to each other, the first optical window 51 and the second optical window 52 are located on both sides of the phase disturbance element 2, and the laser passes through the first optical window 51, the phase disturbance element 2 and the second optical window 52 in sequence.

[0096] In some specific embodiments, the substrate of the optical window is made of high-purity fused silica, such as JGS1 as defined in the Chinese National Standard (GB / T), with a diameter of 25 mm and a thickness of 8 mm. This size design allows it to stably withstand a pressure differential load of 1 atmosphere. Both sides are coated with a broadband antireflective film, with a reflectivity of less than 0.5% in the wavelength range of 600 to 1000 nanometers, balancing the transmittance performance for various laser wavelengths. For the sealing structure, an oxygen-free copper gasket with a hardness of HV40 to 50 and a thickness of 0.5 mm is used to seal the window and the housing flange. Four M4 screws, in conjunction with a pressure ring, apply uniform clamping force. Utilizing the characteristic of oxygen-free copper to undergo plastic deformation and fill microscopic unevenness under high temperature conditions, a reliable vacuum sealing barrier is constructed. This component adopts a modular and detachable design; the window can be removed for cleaning or replacement simply by loosening the pressure ring screws. Reinstallation does not require replacing the gasket, and a single oxygen-free copper gasket can be reused 2 to 3 times, effectively reducing maintenance costs. To prevent contamination, a purge gas protection channel is provided on the inner side of the window near the frosted glass. The continuous airflow barrier effectively prevents the deposition of process byproducts. The outer part of the window exposed to the environment is designed with a structure that facilitates daily maintenance, allowing operators to periodically wipe it clean with a lint-free cloth dampened with alcohol, thereby maintaining the cleanliness and light transmission performance of the optical surface in the long term.

[0097] In one embodiment, the anti-interference phase disturbance module 4 further includes a water-cooling jacket; the side wall of the housing 1 not connected to the optical window is connected to the water-cooling jacket; the water-cooling jacket is provided with water channels; the water channels contain cooling water; when the cooling water in the water channels flows, it is used to improve the heat dissipation efficiency of the housing 1.

[0098] In some specific embodiments, an active cooling system is designed to ensure the safe operation of internal components, especially the samarium-cobalt magnets, in the high-temperature environment near the MOCVD reaction chamber, which can reach 80 to 150 degrees Celsius. This cooling system achieves efficient heat exchange by welding stainless steel water-cooled jackets to the four sides of the sealed housing 1 (excluding the optical window side). The jacket wall thickness is 5 mm, and the internal water channels adopt a serpentine or spiral layout to maximize the heat exchange area. Deionized water is used as the cooling medium, with the flow rate controlled within the range of 2 to 5 liters / minute. The inlet water temperature is maintained at 20 ± 2 degrees Celsius, and the outlet water temperature is strictly controlled below 35 degrees Celsius. According to thermal simulation analysis, when the ambient temperature reaches 120 degrees Celsius and the cooling water flow rate is set to 3 liters / minute, the inner wall temperature of the housing 1 can be effectively suppressed below 55 degrees Celsius. This ensures that the permanent magnets and encapsulation materials inside the magnetic coupler always operate within a safe temperature range far below their 300-degree Celsius tolerance limit, guaranteeing the long-term stable operation of the drive mechanism 3 and the reliability of the vacuum seal.

[0099] In one embodiment, the anti-interference phase disturbance module 4 further includes a purge gas path; the housing 1 is provided with an inlet and an outlet; the purge gas path is connected to the housing 1 through the inlet and the outlet, and is used to provide protective gas to the housing 1 through the inlet and extract protective gas from the housing 1 through the outlet.

[0100] In some specific embodiments, the purge gas system uses high-purity nitrogen or argon as the protective medium. The gas is supplied from an external high-pressure source, first passing through a precision filter with an accuracy of up to 0.01 micrometers to remove micron-sized particulate impurities, then undergoing pressure and flow stabilization by a high-precision flow controller before finally being injected into the sealed cavity. The airflow path is designed as a strictly unidirectional flow pattern: the inlet is located at one end of the housing 1, and the outlet is located at the other end, forming a through-flow airflow channel. The flow rate is controlled within the range of 1 to 3 liters per minute, and the pressure inside the cavity is maintained slightly higher than the reaction chamber pressure, for example, 50 millibars higher, thereby constructing an effective positive pressure barrier. This purging gas path has multiple key functions: First, it uses continuously flowing gas to remove the trace amounts of heat generated by the high-speed rotation of the frosted glass plate 21 and the friction of the bearings, preventing optical distortion caused by local overheating; second, it forms a stable positive pressure protective layer inside the optical window, effectively blocking the reverse diffusion and penetration of corrosive or reactive gases in the reaction chamber; third, it uses the shear force of the airflow to continuously clean the surface of the frosted glass plate 21 and the window, promptly blowing away any trace amounts of process byproducts or particulate contaminants that may be deposited, maintaining the transmittance of the optical path; finally, it provides an inert atmosphere throughout the process, isolating oxygen and preventing oxidation and corrosion of the internal metal shaft 42, magnet components, etc., thereby ensuring the long-term cleanliness and stability of the optical modulation system under extreme process environments.

[0101] In one embodiment, the anti-interference phase disturbance module 4 further includes a temperature detection unit; the temperature detection unit is used to detect the temperature of the optical window component 5 in the anti-interference phase disturbance module and the temperature of the driving mechanism 3; when the temperature of the optical window component 5 exceeds a first preset threshold, a first alarm signal is generated; the first alarm signal is used to control the flow rate of the cooling water to increase; when the temperature of the driving mechanism 3 exceeds a second preset threshold, a second alarm signal is generated; the second alarm signal is used to control the movement speed of the driving mechanism 3 to decrease. The second preset threshold is greater than or equal to the first preset threshold.

[0102] In some specific embodiments, the temperature detection unit includes two K-type thermocouples. One K-type thermocouple is located adjacent to the optical window to sense the effect of thermal radiation on the optical elements in real time, while the other K-type thermocouple is located close to the magnetic coupler to accurately capture the temperature rise of the transmission components. The thermocouple signals are led out to the external control unit via a dedicated vacuum-sealed feedthrough assembly, achieving non-destructive real-time data acquisition. The system has built-in intelligent temperature control logic. Once the temperature at any monitoring point exceeds the preset safety threshold, such as 70 degrees Celsius, an audible and visual alarm mechanism will be immediately triggered, and a linkage protection strategy will be executed simultaneously: on the one hand, the flow rate of the cooling water circulation system will be automatically increased to enhance heat dissipation efficiency; on the other hand, the speed of the drive motor will be actively reduced to reduce frictional heat generation. This will suppress abnormal temperature rise within milliseconds, preventing thermal distortion of the optical window and ensuring that the performance of the magnetic coupler magnets is not affected by high-temperature demagnetization, thus guaranteeing the safe operation and process stability of the equipment under extreme conditions.

[0103] In other specific embodiments, the anti-interference phase disturbance module 4 further includes a control and interface unit, which integrates multi-parameter precision control, intelligent adaptive algorithms, and standardized interaction protocols. This unit supports stepless speed regulation of the motor within the range of 100 to 1200 revolutions per minute, with a steady-state control accuracy better than ±1 revolution per minute; it is also equipped with a dual-channel high-precision flow closed-loop control loop, which stably controls the cooling medium flow rate at 2 to 5 liters per minute and the purge gas flow rate at 1 to 3 liters per minute, respectively, and integrates dual-channel temperature monitoring function with a temperature measurement uncertainty of less than ±1 degree Celsius.

[0104] It is worth noting that the system has both manual and adaptive operating modes: in manual mode, operators can set a fixed rotation speed according to process specifications; in adaptive mode, the host computer software calculates the standard deviation of pixel grayscale in the spot area of ​​the camera-acquired image in real time or performs a fast Fourier transform to quantify the interference contrast. When the real-time contrast exceeds the preset threshold of 0.2, the system automatically triggers a rotation speed increase strategy to enhance the homogenization disturbance of the frosted glass surface until the contrast drops back to a safe threshold below 0.1. This dynamically compensates for the impact of window contamination accumulation and laser power fluctuations during thin film growth, achieving real-time closed-loop optimization of process parameters. At the physical interface level, the unit uses an industrial-grade DB9 serial interface to drive the motor actuator and establishes a data communication link with the host computer via a USB high-speed bus; quick-change compression fittings are deployed on the fluid transmission side to enable quick disassembly and assembly of the cooling water circuit and the purging air circuit; the mounting end is reserved with an M6 type threaded hole array to ensure a rigid connection and convenient integration between the module and the equipment base.

[0105] In some embodiments, the light inlet of the anti-interference phase disturbance module 4 is equipped with a beam splitter, and the light outlet of the anti-interference phase disturbance module 4 is equipped with a silicon photodiode. The beam splitter has a high transmittance of 99% and a reflectance of 1%. 99% of the incident light passes through the beam splitter and enters the reaction chamber, while the 1% reflected light is guided to the silicon photodiode. The system controller continuously collects the electrical signal output by the silicon photodiode, converts it into real-time transmittance data of the optical window, and performs dynamic analysis. When the algorithm detects that the transmittance has decreased by more than 10% relative to the initial reference value, it determines that there is contamination or deposit accumulation on the window surface, and then triggers an alarm mechanism and sends a "clean window" prompt command to the operation terminal, thereby realizing intelligent early warning and closed-loop management of the cleanliness of the optical window without interrupting the process operation.

[0106] In some embodiments, to effectively suppress the transmission of mechanical vibrations generated by the high-speed rotation of the frosted glass to the optical path and avoid spot jitter, a vibration damping base is fixedly connected to the outer side of the housing 1 of the anti-interference phase disturbance module 4. The main body of the base is made of 20 mm thick 6061 aluminum alloy plate, with dimensions of 200 mm × 150 mm and a total weight of 1.5 kg. Its large inertial mass provides a stable mechanical support foundation. Four high-damping rubber vibration damping pads are precisely arranged between the base and the MOCVD machine mounting surface. Special rubber material with a Shore hardness of 60 degrees is selected. Through dynamic optimization design, the natural frequency of the vibration damping system is made to be about 25 Hz. This frequency setting deliberately avoids the main excitation frequency generated by the rotation of the frosted glass, such as 10 Hz, and the low-frequency region that may cause resonance, so that the anti-interference phase disturbance module will not amplify vibrations during operation, but can effectively attenuate high-frequency micro-vibrations. In addition, the base surface is integrated with three standard M6 threaded holes for fixing the optical path adjustment bracket. Together with the fine adjustment mechanism, it can achieve precise calibration of the module's horizontal position and pitch angle, so that the optical axis can maintain pointing stability and alignment accuracy even in complex vibration environments.

[0107] In some examples, the overall size of the anti-interference phase disturbance module 4 is 120×80×60mm, which can be directly connected in series with the existing MOCVD warp measurement optical path without modifying the MOCVD host, making it easy to apply on related equipment and suitable for compact integrated MOCVD equipment.

[0108] like Figure 5As shown, a second embodiment of the present invention provides a wafer warpage measurement system. The system includes a laser 11, a beam expander group 12, a beam splitter 20, a focusing lens 13, an imaging detection unit 14, a processing unit, and an anti-interference phase disturbance module 4 as described in any of the above embodiments. The anti-interference phase disturbance module 4 is disposed between the beam expander group 12 and the beam splitter 20. The laser 11 is used to emit an incident laser beam 41. The beam expander group 12 is used to collimate the incident laser beam 41 emitted by the laser 11 and expand the beam diameter to cover the effective aperture of the anti-interference phase disturbance module 4. The anti-interference phase disturbance module 4 further includes an optical window assembly 5. The optical window assembly 5 is detachably connected to the housing 1. The optical window assembly 5 includes a first optical window 51 and a second optical window 52 disposed opposite to each other. The first optical window 51 and the second optical window 52 are located on both sides of the phase disturbance element, and the incident laser beam 41 passes sequentially through the first optical window 51, the phase disturbance element, and the second optical window 52. The beam splitter 20 is used to split the beam output by the anti-interference phase disturbance module 4 into two parallel beams, a first beam and a second beam; the focusing lens 13 is used to converge the first beam and the second beam onto the surface of the wafer, respectively, to form two light spots; the imaging detection unit 14 is used to receive the reflected light from the surface to obtain a light spot position image containing the two light spots; the processing unit is used to measure the warpage of the wafer based on the light spot position image.

[0109] In some specific embodiments, before deploying the anti-interference phase disturbance module 4, the physical connection between the beam expander and beam splitter 20 in the original optical path is first disconnected. Then, the module is securely mounted on the optical platform of the MOCVD machine in the reaction chamber 18 using a dedicated vibration-damping base. Next, precise optical path alignment is performed: a laser collimator is used to adjust the module's spatial position so that two laser beams with a 10mm spacing and a 4mm spot diameter simultaneously pass through the edge region 211 of the frosted glass plate 21, ensuring that the beam direction is parallel to the module's optical axis. After mechanical positioning, the cooling water circulation pipeline, the purge gas delivery pipeline, and the motor drive control cable are connected sequentially. The system power-on startup process is as follows: first, the cooling water and purge gas supply are turned on. After the system temperature reaches thermal equilibrium, the motor is started to rotate to an initial speed of 300 rpm. Then, by monitoring the interference images acquired by the camera in real time, the motor speed is gradually increased to 600 rpm until the interference contrast is observed to drop to an acceptable range allowed by the process. Finally, the system calibration steps are performed, the initial spot spacing data is measured and recorded, and after confirmation that it is correct, it can be put into normal measurement operation. Thanks to the design characteristics of this module, its access process does not change the original optical path's key geometric parameters such as the incident angle, focal length, and spot spacing, so there is no need to recalibrate the curvature calculation formula, making it easy to use.

[0110] In some specific embodiments, such as Figure 5 As shown, the laser 11 emits a 635nm wavelength beam, which is collimated by an optical fiber collimator to form parallel light. It then enters a 4x beam expander group 12 composed of two convex lenses, which enlarges the beam diameter to improve the uniformity of coverage in the subsequent optical path. The expanded parallel light passes through the parallel light path section located after the beam expander group 12 and before the beam splitter 20, where an anti-interference phase disturbance module 4 composed of rotating frosted glass is embedded. This module disrupts the spatial coherence of the laser by rapid rotation within a single exposure frame, thereby suppressing the problem of spot loss caused by interference destructive processes. The phase-disturbed beam continues forward and is split into two paths by the beam splitter 20, which has a transmittance of 90% and a reflectivity of 10%. The main beam is converged by a focusing lens 13 with a focal length of 150mm and then illuminates the surface of the epitaxial wafer 16. The beam carrying topographic information reflected back from the epitaxial wafer 16 returns through the same focusing lens 13, passes through the camera lens 19, and is received by the CMOS camera 17 for curvature calculation. The auxiliary optical path is focused onto the CMOS sensor target surface via a 100mm focal length imaging lens 15 to observe interference fringes and monitor the stability of the light source in real time. The entire module design does not alter the geometry of the original optical path, requires no adjustment of any optical components or replacement of main unit parts, and the installation process can be completed within 30 minutes, achieving plug-and-play functionality. While ensuring measurement accuracy, this system helps reduce data interruption caused by interference in high-temperature, corrosive, and vacuum environments, providing stable, continuous, and high-precision in-situ warpage monitoring capabilities for the MOCVD process.

[0111] In one embodiment, the processing unit is electrically connected to the drive mechanism 3 of the anti-interference phase disturbance module 4; the processing unit is used to obtain the dynamic interference contrast V(ω) based on the spot position image, the dynamic interference contrast V(ω) is used to represent the visibility of dynamic interference fringes when the spot moves; and the movement speed of the drive mechanism 3 is controlled based on the dynamic interference contrast.

[0112] In some specific embodiments, when the phase disturbance element 2 in the anti-interference phase disturbance module 4 is a frosted glass plate 21, and the driving mechanism 3 is an internal rotor 31; the relationship between the dynamic interference contrast V(ω) and the rotational angular velocity ω of the internal rotor 31 driving the frosted glass plate 21 satisfies: V(ω)≤V0·sinc(ω·Δt·d / Λ); Where Δt is the exposure time of the spot position image, d is the spot diameter in the spot position image, Λ is the spatial coherence length of the surface scattering structure of the frosted glass sheet 21, V0 is the static interference contrast, and sinc is the sampling function.

[0113] In some specific embodiments, the phase disturbance element 2 operates based on the dynamic random modulation of the laser wavefront phase. When the incident laser beam 41 passes through the high-speed rotating frosted glass plate 21, its surface microstructure introduces random phase disturbances into the incident laser beam 41, for example, a characteristic period of 10 μm, compressing the spatial coherence length to the micrometer level. Under typical operating conditions, the frosted glass rotation speed is set to 600 rpm, i.e., a rotation frequency of 10 Hz. Within a single frame exposure time of 2 milliseconds, the frosted glass plate 21 rotates by 7.2 degrees, and its surface feature structure moves a distance of 1.6 mm along the light spot. This displacement is much larger than the feature size of the surface microstructure, thus generating a strong time integration effect on the photosensitive surface of the imaging detection unit 14. Theoretical analysis shows that the interference fringe contrast V is functionally related to the rotational angular velocity ω and the exposure time Δt, approximately satisfying V(ω) = V0•sinc(ω•Δt•d / Λ), where d is the light spot diameter and Λ is the spatial coherence length of the surface scattering structure of the frosted glass. Experimental verification shows that when the rotation speed exceeds 300 rpm, the speckle pattern at different times is fully averaged within the exposure time due to the rapidly moving scattering surface. The interference contrast V rapidly decays to below 0.1, achieving effective blanking of interference fringes and ensuring the signal-to-noise ratio and stability of the optical measurement system in dynamic environments.

[0114] In other specific embodiments, during the experimental verification phase, a test platform simulating the MOCVD growth environment was constructed. The vacuum chamber was heated to 100°C and a mixture of N2 and NH3 gases was introduced to simulate high-temperature corrosion conditions. The test light source was a 635nm wavelength, 5mW laser, and the camera exposure time was set to 2ms with a gain of 0dB. A planar silicon wafer was selected as the epitaxial wafer to simulate a warp-free state, and a controllable optical path difference was introduced through a piezoelectric ceramic-driven mirror to simulate the destructive interference phenomenon. Comparative tests are shown in Table 1.

[0115] Table 1 Comparison Test Data Table

[0116] Comparative test data shows that without this module installed, the system interference contrast is as high as 0.92, the spot loss rate is approximately 15%, and the curvature measurement noise is 0.022m. -1 After connecting the rotating frosted glass module, the interference contrast decreases as the rotation speed increases. Specifically, the contrast drops to 0.25 at 300 rpm, further to 0.08 at 600 rpm, and reaches 0.04 at 1200 rpm, but is accompanied by slight spot jitter. It is worth noting that the spot loss rate of the rotating frosted glass solution is 0% at all rotation speeds, while the curvature noise shows a slight upward trend with the increase of rotation speed.

[0117] Comprehensive evaluation shows that 600 rpm is the optimal operating point. Under this condition, the problem of light spot loss is eliminated, and the additional measurement noise is kept within a negligible range. In addition, a continuous long-term operation test of up to 500 hours was conducted. The results confirmed that the internal temperature of the module was stably maintained at 52±3℃, and the module operated without failure throughout the entire process. The transmittance of the optical window decreased by less than 3%, and could be restored by cleaning. This verifies the reliability and stability of this embodiment in high-temperature and corrosive environments.

[0118] Camera imaging allows for comparative verification of the anti-interference phase disturbance module 4's effect on suppressing laser speckle. Without this module, due to the high coherence of the laser, severe coherence decoupling occurs on the camera target surface, leading to a noticeable dark spot at the center of the laser beam or even complete loss of the beam, such as... Figure 6 As shown, the circle on the left represents the visible light spot, and the dashed line on the right represents the dark spot or the light spot that is missing and therefore invisible. In this example, the interference contrast is as high as 0.92, indicating that there is strong interference noise in the light field, making it unusable for effective measurement. However, after adding the module of this invention and starting the rotating frosted glass at the example speed of 600 revolutions per minute, the camera is able to capture a uniform and full light spot, and the original dark spot disappears, as shown. Figure 7 As shown, the left and right circles represent two visible light spots. In this example, the interference contrast is reduced to 0.08. This contrast result demonstrates that the module can effectively disrupt the spatial coherence of the laser through dynamic scattering, transforming high-contrast interference noise into uniform background light, thereby restoring the integrity of the light spot and providing a more stable optical field basis for subsequent high-precision curvature measurements.

[0119] like Figure 8 As shown in the figure, this graph illustrates the quantitative relationship between interference contrast and the rotational speed of the frosted glass. The horizontal axis represents rotational speed (unit: rpm), ranging from 0 to 1400; the vertical axis represents interference contrast (unitless), ranging from 0.2 to 1.0. The graph contains two curves: "System Measured Interference Contrast" and "Optimal Operating Range." The data shows that the interference contrast of both curves increases as the rotational speed decreases. Specifically, the "System Measured Interference Contrast" curve starts at 0.3 at 1400 rpm, then rapidly increases to 0.7 at 800 rpm and 0.92 at 0 rpm. The "Optimal Operating Range" curve starts at 0.25 at 1400 rpm, then increases to 0.38 at 800 rpm and 0.6 at 0 rpm. The actual measured interference contrast obtained from the tests is generally above the theoretically optimal operating range, indicating that the interference contrast response of the actual system is stronger than theoretically expected.

[0120] In an online measurement system for the warpage and local flatness of 300mm silicon wafers, the beam mixer needs to modulate the beam through axial oscillation. Traditional single-acting substructures generate periodic reaction forces at high-speed scanning speeds, such as 200mm / s, which are transmitted outwards through the housing, causing micro-vibrations in the beam expander and beam splitter. This mechanical interference reduces the signal-to-noise ratio of the interference signal, limiting the accuracy requirements of warpage measurement. This embodiment introduces an anti-interference phase disturbance module. This module reduces the transmission of vibrations to the outside of the housing by using an inertial counterweight unit in conjunction with the beam mixer. By utilizing the collinear arrangement of the center of gravity of the inertial counterweight unit, the center of gravity of the beam mixer, and the center of gravity of the housing, and the radially symmetrical layout of multiple counterweights, the axial excitation force can be counteracted, and the rotational torque on the housing can be weakened, meeting the stability requirements of extreme ultraviolet (EUV) lithography.

[0121] In this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0122] The above description of the embodiments is intended to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope and spirit of the invention are within the scope of the present invention.

Claims

1. An anti-interference phase disturbance module, characterized in that, To reduce laser coherence when measuring wafer warp, the anti-interference phase disturbance module includes a housing, a phase disturbance element, and a drive mechanism. Both the phase disturbance element and the drive mechanism are located inside the housing; The drive mechanism has a fixed end and a moving end; the fixed end is connected to the housing. The moving end is connected to the phase disturbance element. When the driving mechanism is activated, the moving end moves relative to the fixed end to drive the phase disturbance element to perform mechanical movement. The phase disturbance element is located in the laser path for measuring the warp of the wafer; The phase disturbance element is used to disrupt the spatial coherence of the incident laser during mechanical movement to obtain the emitted laser; the emitted laser is used to irradiate the surface of the wafer to measure the warpage of the wafer.

2. The anti-interference phase disturbance module as described in claim 1, characterized in that, The anti-interference phase disturbance module also includes an external rotor; the external rotor is located outside the housing; the drive mechanism includes an internal rotor; The fixed end of the inner rotor is connected to the inner wall of the housing; the moving end of the inner rotor is rotatably connected to the fixed end; the outer rotor is coaxially arranged with the inner rotor, and the outer rotor acts on the moving end of the inner rotor through magnetic force; when the outer rotor rotates, it drives the moving end of the inner rotor to rotate around the fixed end. The phase disturbance element is a frosted glass sheet; the position where the internal rotor is fixedly connected to the frosted glass sheet does not overlap with the position where the laser passes through the frosted glass sheet.

3. The anti-interference phase disturbance module as described in claim 2, characterized in that, A gap is provided between the external rotor and the outer wall of the housing; the housing is made of a non-magnetic material.

4. The anti-interference phase disturbance module as described in claim 2, characterized in that, The frosted glass sheet has an edge region and a central region; The moving end of the internal rotor is connected to the central region, and the laser passes through the frosted glass at the edge region.

5. The anti-interference phase disturbance module as described in claim 2, characterized in that, The internal rotor has an internal cavity that extends through both ends; The laser beam passes through the frosted glass and exits through the inner cavity of the internal rotor.

6. The anti-interference phase disturbance module as described in claim 2, characterized in that, The housing has a detachable flange; the flange is located between the outer rotor and the inner rotor.

7. The anti-interference phase disturbance module as described in claim 1, characterized in that, The driving mechanism includes a transducer; the phase disturbance element is a light mixing rod. The fixed end of the transducer is fixed to the inner wall of the housing; The first moving end of the transducer is fixedly connected to the mixing rod and is used to drive the mixing rod to perform mechanical vibration along the axial direction. When the laser passes through the mixing rod, the mechanical vibration of the mixing rod causes random changes in the optical path, thereby destroying the spatial coherence of the laser.

8. The anti-interference phase disturbance module as described in claim 7, characterized in that, The anti-interference phase disturbance module also includes an inertial counterweight unit; the transducer also has a second moving end, which and the first moving end are used to move simultaneously relative to the fixed end, and the directions of movement are opposite. The inertial counterweight unit is connected to the second moving end of the transducer, and the inertial counterweight unit, the transducer, and the light mixing rod are coaxially arranged. When the transducer drives the light mixing rod to vibrate mechanically along the axial direction, the inertial counterweight unit is used to generate a reverse mechanical vibration that is opposite in phase to the light mixing rod, so as to counteract the reaction force generated when the light mixing rod vibrates.

9. The anti-interference phase disturbance module as described in claim 8, characterized in that, The mass of the inertial counterweight unit is equal to the mass of the light mixing rod.

10. The anti-interference phase disturbance module as described in claim 8, characterized in that, An annular gap is provided between the outer peripheral wall of the inertial counterweight unit and the inner wall of the shell.

11. The anti-interference phase disturbance module as described in claim 8, characterized in that, The center of gravity of the inertial counterweight unit, the center of gravity of the light mixing rod, and the center of gravity of the shell are arranged collinearly so that the reverse inertial force generated by the inertial counterweight unit and the vibration reaction force generated by the light mixing rod are on the same line of action, thereby reducing the rotational torque on the shell.

12. The anti-interference phase disturbance module as described in claim 8, characterized in that, The inertial counterweight unit includes multiple counterweight blocks; the multiple counterweight blocks are distributed at intervals along the axial direction of the light mixing rod, so that the line of action of the resultant force of the reverse inertial force generated by the multiple counterweight blocks coincides with the vibration axis of the light mixing rod, thereby omnidirectionally canceling the eccentric force in each radial direction.

13. The anti-interference phase disturbance module as described in claim 1, characterized in that, The anti-interference phase disturbance module also includes an optical window assembly; The optical window assembly is detachably connected to the housing; The optical window assembly includes a first optical window and a second optical window arranged opposite to each other. The first optical window and the second optical window are located on both sides of the phase scrambling element, and the laser passes through the first optical window, the phase scrambling element and the second optical window in sequence.

14. The anti-interference phase disturbance module as described in claim 8, characterized in that, The anti-interference phase disturbance module also includes a water-cooling jacket; The side wall of the housing that is not connected to the optical window is connected to the water-cooling jacket; The water-cooled jacket is provided with water channels; the water channels contain cooling water. When the cooling water flows in the water channel, it is used to improve the heat dissipation efficiency of the casing.

15. The anti-interference phase disturbance module as described in claim 1 or 14, characterized in that, The anti-interference phase disturbance module also includes a purge gas path; the housing is provided with an inlet and an outlet; The purging gas path is connected to the housing through the inlet and outlet, and is used to provide protective gas to the housing through the inlet and to extract protective gas from the housing through the outlet.

16. The anti-interference phase disturbance module as described in claim 14, characterized in that, The anti-interference phase disturbance module also includes a temperature detection unit; The temperature detection unit is used to detect the temperature of the optical window component in the anti-interference phase disturbance module and the temperature of the driving mechanism. When the temperature of the optical window assembly exceeds a first preset threshold, a first alarm signal is generated; the first alarm signal is used to control the flow rate of the cooling water to increase. When the temperature of the drive mechanism exceeds a second set threshold, a second alarm signal is generated; the second alarm signal is used to control the movement speed of the drive mechanism to decrease; the second set threshold is greater than or equal to the first set threshold.

17. A wafer warpage measurement system, characterized in that, The system includes a laser, a beam expander assembly, a beam splitter, a focusing lens, an imaging detection unit, a processing unit, and an anti-interference phase disturbance module as described in any one of claims 1-16; The anti-interference phase disturbance module is disposed between the beam expander group and the beam splitter; The laser is used to emit a laser beam; The beam expander group is used to collimate the laser beam emitted by the laser and expand the beam diameter to cover the effective aperture of the anti-interference phase disturbance module. The beam splitter is used to split the beam output by the anti-interference phase disturbance module into two parallel beams: a first beam and a second beam. The focusing lens is used to converge the first beam and the second beam onto the surface of the wafer, respectively, to form two light spots; The imaging detection unit is used to receive reflected light from the surface to obtain a spot position image containing the two light spots; The processing unit is used to measure the warpage of the wafer based on the spot position image.

18. The system as claimed in claim 17, characterized in that, The processing unit is electrically connected to the drive mechanism of the anti-interference phase disturbance module; The processing unit is used to obtain a dynamic interference contrast V(ω) based on the spot position image, whereby the dynamic interference contrast V(ω) represents the visibility of dynamic interference fringes when the spot moves; and to control the movement speed of the drive mechanism based on the dynamic interference contrast.

19. The system as claimed in claim 18, characterized in that, The phase disturbance element in the anti-interference phase disturbance module is a frosted glass sheet, and the driving mechanism includes an internal rotor. The relationship between the dynamic interference contrast V(ω) and the rotational angular velocity ω of the ground glass plate driven by the internal rotor satisfies: V(ω)≤V0·sinc(ω·Δt·d / Λ); Where Δt is the exposure time of the spot position image, d is the spot diameter in the spot position image, Λ is the spatial coherence length of the surface scattering structure of the frosted glass sheet, V0 is the static interference contrast, and sinc is the sampling function.

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