Wafer cleaning method and wafer cleaning device using a speed measuring wheel brake

Abstract

The application provides a kind of wafer cleaning speed measuring wheel brake method and wafer cleaning device, it is applied to the speed measuring wheel being provided with electromagnetic brake, electromagnetic brake includes stator, rotor, coil winding, the side of stator close to rotor includes friction plate, rotor is fixedly connected with the rotating shaft of speed measuring wheel, method includes: first pulse current is passed to coil winding, so that coil winding magnetization, attract stator to move close to rotor direction until contact friction plate and brake;Second pulse current is passed to coil winding, so that coil winding demagnetization, stator and friction plate are separated, and the brake limit of speed measuring wheel is released.The application magnetizes coil winding by first pulse current, so that coil winding generates constant magnetic field, and electromagnetic brake does not need to be continuously energized when maintaining brake state or maintaining release state of speed measuring wheel, thereby reducing the heat output of coil winding.

Description

Technical Field

[0001] This invention belongs to the field of wafer manufacturing technology, and specifically relates to a method for braking a speed measuring wheel during wafer cleaning and a wafer cleaning device. Background Technology

[0002] The integrated circuit industry is the core of the information technology industry, playing a crucial role in promoting the digital and intelligent transformation and upgrading of the manufacturing industry. Chips are the carriers of integrated circuits, and chip manufacturing involves processes such as integrated circuit design, wafer fabrication, wafer processing, electrical measurement, dicing, packaging, and testing. Among these, chemical mechanical polishing (CMP) is one of the five core processes in wafer fabrication. After CMP, a large amount of particulate matter remains on the wafer surface; therefore, post-processing such as cleaning and drying is necessary.

[0003] The wafer cleaning device mainly consists of a tank, inside which are installed drive wheels and speed measuring wheels to vertically support the wafer and drive its rotation. Roller brushes positioned on both sides of the wafer roll around its axis to contact and clean the wafer surface, removing particles. The speed measuring wheels rotate with the wafer, and a rear-mounted sensor calculates the number of rotations of the speed measuring wheels, thereby estimating the wafer's rotational speed.

[0004] Since both the drive wheel and the speed measuring wheel are in contact with the edge of the wafer, some contaminants adhere to them during the cleaning process. These contaminants are then transferred to the wafer through contact, causing edge contamination and residue. To address this issue, a roller rinsing function is needed to rinse the drive wheel and speed measuring wheel with deionized water to remove residual impurities and reduce their impact on wafer quality. However, because the speed measuring wheel has a small moment of inertia, even a small flow of water can cause it to rotate. This results in the speed measuring wheel not stopping rotating during wafer placement, creating sliding friction between the speed measuring wheel and the wafer, which can damage the wafer and affect the circuitry on its surface. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a method for braking a speed measuring wheel during wafer cleaning and a wafer cleaning apparatus.

[0006] In a first aspect, an embodiment of the present invention provides a method for braking a speed measuring wheel during wafer cleaning, applied to a speed measuring wheel equipped with an electromagnetic brake. The electromagnetic brake includes a stator, a rotor, and a coil winding. The stator includes a friction plate on its side near the rotor. The rotor is fixedly connected to the shaft of the speed measuring wheel. The method includes:

[0007] A first pulse current is applied to the coil winding to magnetize it, attracting the stator to move towards the rotor until it contacts the friction plate for friction braking. The coil winding is fixed to the stator of the electromagnetic brake.

[0008] A second pulse current is applied to the coil winding to demagnetize it, causing the stator to disengage from the friction plate and releasing the braking restriction on the speed measuring wheel.

[0009] In some embodiments, the step of applying a first pulse current to the coil winding to magnetize the coil winding and attract the stator to move towards the rotor until it contacts the friction plate for friction braking includes:

[0010] A first pulse current is passed through the coil winding, causing the coil winding to generate a magnetic field that attracts the rotor. The rotor comes into contact with the friction plate and rubs against it, causing the speed measuring wheel to stop rotating.

[0011] The first pulse current is stopped flowing into the coil winding, and the rotor maintains its current braking state.

[0012] In some embodiments, the step of applying a second pulse current to the coil winding to demagnetize the coil winding, disengaging the stator from the friction plate, and releasing the braking restriction on the speed measuring wheel includes:

[0013] A second pulse current is passed through the coil winding to demagnetize the coil winding, and the stator is reset and disengaged from the friction plate; wherein the first pulse current and the second pulse current have opposite current directions;

[0014] The second pulse current is stopped from flowing into the coil winding, the stator maintains its current reset state, and the speed measuring wheel rotates synchronously with the wafer.

[0015] In some embodiments, the electromagnetic brake further includes a sealing ring sleeved on the outside of the stator and the rotor, the sealing ring being fixedly connected to the stator and movably connected to the rotor, for preventing cleaning fluid used for cleaning wafers from entering the interior of the electromagnetic brake.

[0016] In some embodiments, a heat dissipation hole is provided on the side of the sealing ring, and a blocking member is provided at the outlet of the heat dissipation hole near the wafer to prevent the cleaning fluid used to clean the wafer from entering the heat dissipation hole.

[0017] In some embodiments, the hole spacing on the side of the heat dissipation holes closer to the rotating shaft is greater than the hole spacing on the side farther from the rotating shaft.

[0018] In some embodiments, the speed measuring wheel braking method further includes:

[0019] The thickness and temperature of the friction pad are monitored in real time, and the monitoring results are logically compared with preset alarm values ​​to issue corresponding alarm information.

[0020] In some embodiments, the speed measuring wheel braking method further includes:

[0021] The magnetic strength of the magnetic field generated by the coil winding is detected in real time, and the magnitude of the first pulse current or the second pulse current supplied to the coil winding is adjusted according to the detection results.

[0022] Secondly, an embodiment of the present invention provides a wafer cleaning apparatus for implementing the speed measuring wheel braking method described in the first aspect, comprising:

[0023] The housing, the space inside which is used to hold the wafer and provide wafer cleaning;

[0024] The cleaning assembly includes roller brushes located on both sides of the wafer, the roller brushes rotating along their axial direction to perform rolling scrubbing on the wafer surface;

[0025] The driving assembly includes a driving wheel and a speed measuring wheel that contact the edge of the wafer. The driving wheel is used to define and drive the wafer to rotate along its axis in a vertical plane, and the speed measuring wheel is passively rotated under the drive of the wafer.

[0026] The speed measuring wheel is connected to an electromagnetic brake. A first pulse current is applied to the electromagnetic brake to brake the speed measuring wheel, or a second pulse current is applied to release the brake on the speed measuring wheel.

[0027] In some embodiments, the electromagnetic brake further includes a sealing ring sleeved on the outside of the stator and the rotor, the sealing ring being fixedly connected to the stator and movably connected to the rotor, for preventing cleaning fluid used for cleaning wafers from entering the interior of the electromagnetic brake.

[0028] Compared with the prior art, the beneficial effects of the present invention include:

[0029] 1) This embodiment uses an electromagnetic brake to ensure that the wafer and the speed measuring wheel stop rotating simultaneously, preventing relative slippage between the speed measuring wheel and the wafer that could damage the wafer surface. It also ensures the accuracy of the speed measuring wheel's detection of the wafer's rotational speed. During braking, a first pulse current magnetizes the coil windings, generating a constant magnetic field. The electromagnetic brake does not need continuous energization to maintain or de-energize the speed measuring wheel, thus reducing heat generation in the coil windings. Furthermore, the instantaneous first pulse current flowing through the coil windings significantly increases the upper limit of the generated magnetic force, improving braking response speed and resulting in superior dynamic braking characteristics.

[0030] 2) In this embodiment, a sealing ring is set on the outside of the stator and rotor. The sealing ring is fixedly connected to the stator and movably connected to the rotor, so that the rotor can rotate within the sealing ring and move along the axis of the speed measuring wheel. While ensuring the movement of the rotor, it can minimize the entry of cleaning fluid used for cleaning wafers into the electromagnetic brake, which could corrode and damage the stator, rotor, or friction plates. Heat can also be dissipated through the heat dissipation holes on the sealing ring, preventing the heat generated by the coil windings from concentrating inside the electromagnetic brake. A blocking element is set at the outlet of the heat dissipation hole to prevent cleaning fluid from entering the electromagnetic brake through the heat dissipation hole. The hole spacing on the side of the heat dissipation hole closer to the shaft is greater than the hole spacing on the side farther from the shaft, ensuring the heat dissipation effect. Attached Figure Description

[0031] The advantages of the present invention will become clearer and easier to understand through the following detailed description in conjunction with the accompanying drawings, which are merely illustrative and do not limit the scope of protection of the present invention, wherein:

[0032] Figure 1 A schematic diagram of the structure of a wafer cleaning apparatus provided in an embodiment of the present invention is shown;

[0033] Figure 2A A schematic diagram of the structure of an electromagnetic brake provided in an embodiment of the present invention is shown;

[0034] Figure 2B A schematic diagram of the structure of an electromagnetic brake provided in another embodiment of the present invention is shown;

[0035] Figure 3A A flowchart of a speed measuring wheel braking method according to an embodiment of the present invention is shown;

[0036] Figure 3B A flowchart of a speed measuring wheel braking method provided in another embodiment of the present invention is shown;

[0037] Figure 4 A rectangular current waveform diagram provided in an embodiment of the present invention is shown;

[0038] Figure 5 The diagram shows a trapezoidal current waveform provided in an embodiment of the present invention;

[0039] Figure 6 A sinusoidal current waveform diagram provided in an embodiment of the present invention is shown;

[0040] Figure 7 A logic control diagram of a magnetic control module and a wear detection module provided in an embodiment of the present invention is shown;

[0041] Figure 8 A schematic diagram of the controller provided in an embodiment of the present invention is shown;

[0042] Figure 9 A schematic diagram of the shaping circuit provided in an embodiment of the present invention is shown. Detailed Implementation

[0043] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0044] The accompanying drawings in this specification are schematic diagrams to aid in illustrating the concept of the invention, and schematically show the shapes of the various parts and their interrelationships. It should be understood that, in order to clearly demonstrate the structure of the components in the embodiments of the invention, the drawings are not drawn to the same scale, and the same reference numerals are used to indicate the same parts in the drawings. The technical solutions of the invention will be further described below through specific embodiments.

[0045] In this invention, a wafer (w) is also called a substrate (Substrate), which has the same meaning and practical function.

[0046] An embodiment of the present invention provides a braking method for a speed measuring wheel used for cleaning wafer w, which is applied to a speed measuring wheel 220 equipped with an electromagnetic brake. The electromagnetic brake includes a stator 500, a rotor 600, and a coil winding 520. The side of the stator 500 near the rotor 600 includes a friction plate 510. The rotor 600 is fixedly connected to the shaft of the speed measuring wheel 220.

[0047] like Figure 3A As shown, the braking method for the speed measuring wheel includes:

[0048] S11. A first pulse current is applied to the coil winding to magnetize the coil winding, attracting the stator to move towards the direction closer to the rotor until it contacts the friction plate for friction braking.

[0049] S12. A second pulse current is applied to the coil winding to demagnetize the coil winding, causing the stator to disengage from the friction plate and releasing the braking restriction on the speed measuring wheel.

[0050] Specifically, after the coil winding 520 is magnetized, it attracts the rotor 600 to move towards the stator 500 until it comes into contact with the friction plate 510 for friction braking; after the coil winding 520 is demagnetized, the stator 500 is reset and disengaged from the friction plate 510, thus releasing the braking restriction on the speed measuring wheel 220.

[0051] It should be noted that steps S1 and S2 in this embodiment do not have a fixed order. Steps S1 or S2 can be executed as needed to brake or release the speed measuring wheel, all of which are within the scope of protection of this application.

[0052] This embodiment uses an electromagnetic brake to ensure that the wafer w and the speed measuring wheel 220 stop rotating simultaneously, preventing relative slippage between the speed measuring wheel 220 and the wafer w that could damage the surface of the wafer w. It also ensures the accuracy of the speed measuring wheel 220's detection of the wafer w's rotational speed. During braking, a first pulse current magnetizes the coil winding 520, generating a constant magnetic field. During demagnetization, a second pulse current demagnetizes the coil winding 520. The electromagnetic brake does not require continuous energization when maintaining the braking or de-energizing state of the speed measuring wheel 220, thus reducing the heat generated by the coil winding 520. Furthermore, because a momentary first pulse current is applied to the coil winding 520, the upper limit of the generated magnetic force is significantly increased, improving the braking response speed and resulting in superior dynamic braking characteristics.

[0053] In this embodiment, the speed measuring wheel braking method includes:

[0054] A first pulse current is passed through the coil winding 520, causing the coil winding 520 to generate a magnetic field that attracts the rotor 600. The rotor 600 comes into contact with the friction plate 510 and rubs against it, causing the speed measuring wheel 220 to stop rotating.

[0055] The first pulse current is stopped being supplied to the coil winding 520, and the rotor 600 maintains its current braking state.

[0056] A second pulse current is passed through the coil winding 520, causing the coil winding 520 to be demagnetized, the stator 500 to be reset and disengaged from the friction plate 510; wherein the current directions of the first pulse current and the second pulse current are opposite.

[0057] The second pulse current is stopped being supplied to the coil winding 520, the stator 500 maintains its current reset state, and the speed measuring wheel 220 rotates synchronously with the wafer w.

[0058] The main inventive point of this embodiment is that no current needs to be continuously supplied to the coil winding 520 during the state holding phase. Traditional electromagnetic brakes, whether energized or de-energized, require a continuous current supply to the coil winding 520 during the braking state holding or de-energizing phases to maintain the current state. This braking method causes the electromagnetic brake to consume electrical energy throughout the braking process, thereby increasing the heat generated by the electromagnetic brake. This embodiment uses a first pulse current and a second pulse current, and replaces the core of the coil winding 520 with a permanent magnet. The permanent magnet generates and maintains the magnetic field, eliminating the need for continuous energization in the coil winding 520 during the state holding phase. This significantly reduces the energy loss of the electromagnetic brake during operation, and reduces the heat generated and power consumption of the coil winding 520.

[0059] The electromagnetic brake operates in four stages: instantaneous braking, braking holding, instantaneous release, and release holding. During the instantaneous braking and release stages, instantaneous first and second pulse currents in different directions are supplied to the coil winding 520, magnetizing or demagnetizing it, thereby braking or releasing the speed measuring wheel 220. After the instantaneous braking stage ends, the speed measuring wheel 220 stops rotating, and the supply of the instantaneous first pulse current to the coil winding 520 ceases. At this point, the coil winding 520 remains magnetized, and the speed measuring wheel 220 remains in the braking stage. Similarly, after the instantaneous release stage ends, the speed measuring wheel 220 resumes rotation, and the supply of the instantaneous second pulse current to the coil winding 520 ceases. The coil winding 520 remains demagnetized, and the speed measuring wheel 220 remains in the release holding stage.

[0060] Specifically, such as Figure 3B As shown, the braking process provided in this embodiment includes:

[0061] S21. Instantaneous braking stage: In the initial state, the rotor 600 disengages from the stator 500 under the elastic force of the spring plate 700, and the speed measuring wheel 220 rotates normally. When it is necessary to brake the speed measuring wheel 220, the first pulse current is passed through the coil winding 520, and the electromagnetic circuit of the coil winding 520 is positively energized. The electromagnetic attraction generated by the positive energizing current is sufficient to overcome the elastic reaction torque of the spring plate 700, so that the rotor 600 moves towards the stator 500 until the armature 610 on one side of the rotor 600 abuts against the friction plate 510. As the stator 500 and the friction plate 510 come into contact, friction is generated, and the stator 500 stops rotating, thus realizing instantaneous braking of the speed measuring wheel 220.

[0062] S22, Braking and Holding Stage: Since the permanent magnet circuit of the coil winding 520 is already a closed magnetic circuit, after the first pulse current is cut off, since the permanent magnet can remember the current magnetic circuit operating point, after applying pulse current to the electromagnet to achieve braking, there is no need to supply power to the coil winding 520. The coil winding 520 can still maintain the magnetic field state of the instantaneous braking stage, and the speed measuring wheel 220 is still in the braking state, entering the stable braking and holding stage.

[0063] S23, Instantaneous Release Stage: When it is necessary to release the braking of the speed measuring wheel 220, a second pulse current opposite to the direction of the first pulse current is passed into the coil winding 520. The reverse excitation current induces a reverse excitation flux in the electromagnetic circuit, which is superimposed on the positive polarization flux flowing in the permanent magnet circuit. The reverse magnetic field generated by the coil winding 520 weakens the magnetism of the permanent magnet instantaneously. The electromagnetic attraction force on the armature 610 on one side of the rotor 600 is less than the elastic reaction torque applied by the spring plate 700. Under the elastic force of the spring plate 700, the rotor 600 moves away from the stator 500 and disengages from the friction plate 510. The friction between the armature 610 and the friction plate 510 disappears, the braking state of the speed measuring wheel 220 is released, and the speed measuring wheel 220 resumes synchronous rotation with the wafer w.

[0064] S24. Release holding stage: Since the permanent magnet circuit of the coil winding 520 is a closed magnetic circuit, after the second pulse current is cut off, the coil winding 520 can still maintain the magnetic field state of the instantaneous release stage, and the speed measuring wheel 220 is still in the brake release state, entering the stable release holding stage.

[0065] Compared to ordinary energized and de-energized electromagnetic brakes, the significant difference in the braking method provided in this embodiment is that no current is continuously supplied to the coil winding 520 during the state holding phase. Both energized and de-energized electromagnetic brakes require a continuous current supply to the coil winding 520 during the braking holding or releasing phase to ensure the electromagnetic force acting on the armature 610 remains constant. This method causes the electromagnetic brake to consume energy during the holding phase, increasing heat generation and reducing system efficiency. This embodiment utilizes the easy magnetization and demagnetization of permanent magnets, allowing the electromagnetic force maintaining the state of the armature 610 to be generated and maintained by the permanent magnet. Therefore, no continuous energization is required in the coil winding 520 during the state holding phase, significantly reducing energy loss and heat generation during operation, and solving the problem of high power consumption in existing electromagnetic brakes. Furthermore, since the braking method proposed in this embodiment does not rely on continuous power supply, its reliability is also improved compared to existing electromagnetic braking methods.

[0066] It should be noted that this invention does not impose specific requirements or special limitations on the waveform of the current; it can be as follows: Figure 4The rectangular wave shown can also be as follows: Figure 5 The trapezoidal wave shown can also be as follows: Figure 6 The sine wave shown, and other waveforms not listed, are also within the scope of disclosure and protection of this embodiment.

[0067] In this embodiment, the speed measuring wheel braking method further includes:

[0068] The thickness and temperature of the friction plate 510 are monitored in real time. The monitoring results are logically compared with the preset alarm values, and corresponding alarm information is issued.

[0069] The braking method provided in this embodiment also includes real-time monitoring of the wear of the friction pad 510 to remind the operator to replace it in a timely manner. It should be noted that this embodiment does not impose specific requirements or limitations on the thickness detection method of the friction pad 510; for example, it can be ultrasonic detection, infrared detection, microwave detection, or X-ray detection. Of course, other detection methods can also be used in this embodiment; in other words, any detection method that can achieve real-time detection of the thickness of the friction pad 510 can be used in this invention.

[0070] To facilitate a better understanding of the implementation process of the braking method provided in this embodiment by those skilled in the art, this embodiment uses ultrasonic testing as an example to exemplarily describe the thickness detection process of the friction plate 510 as follows:

[0071] A signal transmitter and a signal receiver are provided on one side surface of the friction plate 510. When the friction plate 510 is not in use, the signal transmitter on the surface of the friction plate 510 emits an ultrasonic signal. After the ultrasonic signal propagates inside the friction plate 510, it is reflected by the other side surface of the friction plate 510 and received by the signal receiver on the surface of the friction plate 510. The emission time and the reception time of the ultrasonic signal are recorded, and the time difference between the emission time and the reception time is calculated and denoted as M0.

[0072] After the friction plate 510 has been used for a period of time, the transmission and reception times of the ultrasonic signal are measured again using the above method. The time difference between the transmission and reception times of the ultrasonic signal after the friction plate 510 is worn is calculated and denoted as M1.

[0073] The propagation speed of the ultrasonic signal within the friction plate 510 is corrected based on the temperature of the friction plate 510, and the corrected propagation speed of the ultrasonic signal is denoted as V.

[0074] The formula for calculating the thickness wear of friction plate 510 is as follows: The wear amount of the friction plate 510 is compared with the preset value. An alarm message is issued based on the comparison result, prompting maintenance personnel to replace the friction plate 510 with spare parts in a timely manner.

[0075] In this embodiment, the speed measuring wheel braking method further includes:

[0076] The magnetic strength of the magnetic field generated by the coil winding 520 is detected in real time, and the magnitude of the first pulse current or the second pulse current supplied to the coil winding 520 is adjusted according to the detection results.

[0077] Figure 1 The illustrated embodiment provides a wafer cleaning apparatus for implementing the speed measuring wheel braking method provided in the above embodiment, which includes:

[0078] Housing 100, the interior of which is used to accommodate wafer w and provide space for cleaning wafer w;

[0079] The cleaning assembly 300 includes roller brushes located on both sides of the wafer w, which rotate along their axial direction to perform rolling scrubbing on the surface of the wafer w.

[0080] The drive assembly 200 includes a drive wheel and a speed measuring wheel 220 that are in contact with the edge of the wafer w. The drive wheel is used to define and drive the wafer w to rotate along its axis in a vertical plane, and the speed measuring wheel 220 is passively rotated under the drive of the wafer w.

[0081] The speed measuring wheel 220 is connected to an electromagnetic brake. A first pulse current is applied to the electromagnetic brake to brake the speed measuring wheel 220, or a second pulse current is applied to release the brake on the speed measuring wheel 220.

[0082] In this embodiment, the cleaning assembly 300 includes two roller brushes, which are respectively disposed on both sides of the wafer w. One end of each roller brush is connected to a drive mechanism, which drives the roller brush to rotate relative to the surface of the wafer w. The two roller brushes rotate in opposite directions to perform rolling brushing on the surface of the wafer w; for example, one roller brush rotates clockwise while the other rotates counterclockwise. Particularly preferably, the rotation direction of the two roller brushes is opposite to the surface of the wafer w, so that the roller brushes generate an upward frictional force on the wafer w when rotating, maximizing the relative speed between the roller brushes and the wafer w in the area where the cleaning fluid falls, thereby improving the cleaning effect.

[0083] It should be noted that this embodiment does not impose specific requirements or limitations on the structure and material of the roller brush. Exemplarily, the roller brush typically includes a hollow shaft and a sponge covering the outer periphery of the hollow shaft. The roller brush is mounted on a pair of rotatable roller brush fixing structures. One end of the fixing structure is equipped with a liquid inlet shaft, through which liquid (cleaning fluid or rinsing fluid) is supplied to the interior of the hollow shaft, resulting in a jet of liquid. Several liquid outlet holes are evenly distributed on the hollow shaft, allowing the liquid inside the shaft to pass through the outlet holes to reach the sponge and seep out, thereby moisturizing the roller brush and forming a liquid film on the sponge surface. This prevents direct contact between the sponge and contaminants, which could cause the contaminants on the sponge to re-adhere and contaminate the wafer w.

[0084] like Figure 1 As shown, the drive assembly 200 includes a first drive wheel 210, a second drive wheel 230, and a speed measuring wheel 220. The speed measuring wheel 220 is located at the bottom edge of the wafer w, and the first drive wheel 210 and the second drive wheel 230 are symmetrically arranged on both sides of the speed measuring wheel 220 with the speed measuring wheel 220 as the center. During wafer w cleaning, the first drive wheel 210 and the second drive wheel 230 rotate under the drive of their respective drive motors. The roller brushes on both sides of the wafer w contact the surface of the wafer w and rotate around the axis of the roller brushes. Under the action of friction, the wafer w, which is vertically arranged in the gap between the two roller brushes, rotates around the axis of the wafer w. The rolling roller brushes contact the rotating wafer w to remove contaminants from the surface of the wafer w. During the rotation of the wafer w, the speed measuring wheel 220 is driven to rotate passively. The number of rotations of the speed measuring wheel 220 is calculated by a rear-mounted sensor, thereby estimating the rotational speed of the wafer w and monitoring the cleaning status of the wafer w.

[0085] Figure 1 In the embodiment shown, the wafer cleaning apparatus further includes two spray bars located above the cleaning assembly 300 and parallel to each other, with multiple nozzles evenly distributed on the spray bars, and the cleaning fluid sprayed by the nozzles at least covering the contact area between the cleaning assembly 300 and the wafer w.

[0086] Figure 2A In the embodiment shown, the electromagnetic brake includes a drive shaft 400 and a stator 500 and a rotor 600 sleeved on the drive shaft 400. A spring plate 700 is sleeved on the shoulder of the drive shaft 400. In the free state, the spring plate 700 abuts against one end of the rotor 600, so that a braking gap is formed between the stator 500 and the rotor 600.

[0087] exist Figure 2A In the illustrated embodiment, the stator 500 is detachably fixed to the surface of the base 800 by connecting bolts. The drive shaft 400 passes through the base 800, with one end connected to the stator 500. A bearing 810 is disposed between the drive shaft 400 and the base 800, so that while the drive shaft 400 drives the rotor 600 to rotate, the stator 500 remains fixed on the base 800. The stator 500 has a coil winding 520 surrounding the drive shaft 400 inside. The coil winding 520 includes a permanent magnet and a coil winding 520 wound around the surface of the permanent magnet.

[0088] In this embodiment, the permanent magnet is a magnetic material with high remanence, low coercivity, and the ability to remember the current operating point of the magnetic circuit. For example, it can be an AlNiCo permanent magnet or a NdFeB permanent magnet. Its magnetization state can be instantaneously changed by applying a first pulse current or a second pulse current in different directions, while simultaneously remembering the current magnetization state. It can maintain the current magnetization state even without applying a pulse current, until a reverse transient second pulse current or first pulse current is applied, causing a change in the magnetic field of the coil winding 520.

[0089] exist Figure 2A In the embodiment shown, a friction plate 510 is disposed at one end of the coil winding 520 near the rotor 600, and an armature 610 is disposed on the surface of the rotor 600. After the coil winding 520 is magnetized, it attracts the armature 610, so that the armature 610 contacts the friction plate 510 for friction braking.

[0090] During wafer cleaning, cleaning fluid is continuously sprayed onto both surfaces of the wafer, and two rotating rollers clean each surface separately. The speed measuring wheel is typically located below the wafer. During cleaning, the cleaning fluid is sprayed onto the wafer, then carried by the wafer to the vicinity of the speed measuring wheel, and subsequently passes over the rollers. Therefore, the cleaning fluid near the speed measuring wheel contains not only compounds from the cleaning fluid itself but also contaminants from the wafer or the rollers.

[0091] However, in order to provide braking space for the rotor 600, there is a gap between the stator 500 and the rotor 600 of the electromagnetic brake. The cleaning fluid itself or the contaminants carried in the cleaning fluid may enter the electromagnetic brake through the gap, causing rapid wear of the stator 500, rotor 600 or friction plates.

[0092] For this reason, see Figure 2B The electromagnetic brake may also include a sealing ring sleeved on the outside of the stator 500 and the rotor 600. The sealing ring is fixedly connected to the stator 500 and movably connected to the rotor 600. It is used to prevent the cleaning fluid used to clean the wafer from entering the interior of the electromagnetic brake and to improve the service life of the electromagnetic brake.

[0093] In this embodiment, a heat dissipation hole is provided on the side of the sealing ring, and a blocking member is provided on the side of the outlet of the heat dissipation hole near the wafer to prevent the cleaning fluid used to clean the wafer from entering the heat dissipation hole. Heat is dissipated through the heat dissipation hole on the sealing ring, thus avoiding the heat of the coil winding from concentrating inside the electromagnetic brake.

[0094] Additionally, if the roller brush has a protective baffle, the cleaning fluid may drip down the baffle and enter the heat dissipation holes. Therefore, see [link to relevant documentation]. Figure 2B The blocking element at the outlet of the heat dissipation hole can be a shielding layer 910 that partially covers the heat dissipation hole. The side of the shielding layer 910 close to the wafer is sealed with the sealing ring, and the side away from the wafer has an opening to expose the heat dissipation hole, so as to ensure effective heat dissipation of the coil winding.

[0095] In this embodiment, the spacing between the heat dissipation holes on the side closer to the rotating shaft is greater than the spacing on the side farther from the rotating shaft to ensure effective heat dissipation. For example, the cross-section of the heat dissipation holes can be triangular, trapezoidal, elliptical, etc., all of which are within the scope of protection of this application.

[0096] exist Figure 7 In the embodiment shown, the electromagnetic brake also includes a wear detection module, which is disposed at the friction plate 510 and is used to detect the thickness and temperature of the friction plate 510 in real time and issue corresponding alarm information.

[0097] Specifically, the wear detection module includes a thickness sensor and a temperature sensor embedded in the friction plate 510. The thickness sensor and the temperature sensor are electrically connected to the controller independently, and the controller provides feedback to control the alarm.

[0098] It should be noted that this embodiment does not impose specific requirements or special limitations on the structure and type of the thickness sensor. For example, it can be an ultrasonic sensor, an infrared sensor, an X-ray sensor, or a microwave sensor.

[0099] Preferably, in this embodiment, an ultrasonic sensor is selected as the thickness sensor. The ultrasonic sensor can send and receive ultrasonic signals. Since the propagation speed of ultrasonic waves in the medium material of the friction plate 510 is fixed, the thickness wear of the friction plate 510 can be calculated by using the time difference between the transmitted and received signals.

[0100] To prevent inaccurate detection due to uneven wear of the friction plate 510, the wear detection module includes at least two ultrasonic sensors evenly distributed within the friction plate 510, with the detection information from one of the ultrasonic sensors serving as a redundant signal for verification.

[0101] It should be noted that this embodiment does not impose specific requirements or special limitations on the material of the friction plate 510. Preferably, in order to facilitate processing and achieve high wear resistance, the friction plate 510 can be made of steel fiber reinforced semi-metallic or organic mineral composite organic material.

[0102] Considering the influence of ambient temperature on the propagation speed of ultrasonic waves, it is necessary to calibrate the propagation speed of ultrasonic signals according to the ambient temperature. Therefore, a temperature sensor needs to be installed inside the friction pad 510 to perform temperature compensation on the measured thickness value of the friction pad 510.

[0103] In this embodiment, the controller is electrically connected to both the ultrasonic sensor and the temperature sensor. The controller controls the ultrasonic sensor to emit ultrasonic pulse signals. The ultrasonic signals propagate and reflect within the friction pad 510 medium, generating echoes. The ultrasonic sensor records the emission time and the echo reception time, sending the measured time information to the controller. The controller calculates the time difference based on the emission and reception times. Simultaneously, the temperature sensor sends ambient temperature detection information to the controller. The controller calibrates the ultrasonic signal propagation speed based on the ambient temperature and calculates the thickness wear of the friction pad 510 based on the calibrated propagation speed and time difference. The signal detection and control module connects the alarm information to the alarm via communication interfaces such as RS485, RS232, or RS422, and sends command signals to the alarm through these communication interfaces.

[0104] Figure 7 In the embodiment shown, the electromagnetic brake further includes a magnetic control module, which is used to detect the strength of the magnetic field generated by the coil winding 520 and to provide feedback control over the magnitude of the first pulse current or the second pulse current.

[0105] Specifically, the magnetic control module includes a magnetic sensor embedded in the friction plate 510, the magnetic sensor is electrically connected to a controller, and the controller provides feedback control to a pulse power supply electrically connected to the coil winding 520, which is used to control the first pulse current or the second pulse current output by the pulse power supply.

[0106] After prolonged use of the electromagnetic brake, the coil winding 520 will generate hysteresis loss, and the friction plate 510 will also wear down, causing the braking gap to increase, which will affect the magnetic field state generated by the coil winding 520. In addition to prompting the operator to replace the friction plate 510 as soon as possible, this embodiment monitors the magnetic field state in real time and adjusts the magnitude of the first pulse current or the second pulse current in a timely manner to compensate for the attenuation of magnetic field strength caused by hysteresis loss and increased braking gap.

[0107] It should be noted that this embodiment does not impose specific requirements or special limitations on the structure and type of magnetic sensor, such as Hall sensor, MR sensor or MI sensor, etc.

[0108] In this embodiment, as Figure 8The diagram shows the overall design principle of the controller, which includes a microcontroller, a waveform generation circuit, a shaping circuit, and a power amplifier circuit. A reference current signal waveform for the target current is input to the microcontroller. The input DC current signal passes through the waveform generation circuit, shaping circuit, and power amplifier circuit, feeding back the resulting current waveform to the microcontroller. The microcontroller compares the obtained current waveform with the reference current signal waveform and controls the commutation (i.e., switching between the first and second pulse currents) and pulse width of the pulse current signal by switching a timer on and off. Utilizing the waveform impulse equivalence principle, the desired current waveform is obtained. Finally, the amplification factor of the power amplifier circuit is adjusted to achieve the theoretically desired current waveform signal.

[0109] Figure 9 The illustrated embodiment provides a design schematic of a shaping circuit, including capacitor C1, a small power supply, capacitor C2, and a sliding rheostat R. L A small power supply charges and discharges capacitors C1 and C2, and the charging and discharging process is controlled by a microcontroller. Capacitor C1 and the sliding rheostat R... L An LC damping oscillation circuit is constructed. By controlling capacitor C1, the damping effect of the LC oscillation circuit on the input current is adjusted, and the input current waveform is shaped. The Hall element can detect the rising and falling edges of the input current waveform and the corresponding time information and feed them back to the microcontroller. The microcontroller controls the charging and discharging process of capacitor C2, thereby forming a one-to-one correspondence with the rising and falling edges of the input waveform, and thus shaping the rising and falling edges of the input current waveform.

[0110] When shaping the rising and falling edges of the current waveform, the Hall element first feeds back the detected rising and falling edges of the input waveform and their corresponding timing information to the microcontroller. The microcontroller then controls the charging and discharging process of capacitors C1 and C2. When the input current waveform is at its rising edge, the microcontroller controls the switch to close, and capacitors C1 and C2 charge, thus attenuating the input signal current. Capacitor C1 promotes the attenuation effect of the LC oscillation circuit, making the rising edge of the input current waveform smoother. When the input current waveform is at its falling edge, the microcontroller controls the switch to open, and capacitor C1 discharges. The direction of the discharge current is opposite to the original input current direction. Therefore, C1 promotes the reduction of the original current, making the falling edge of the input current waveform steeper. This forms a one-to-one correspondence with the rising and falling edges of the input waveform, achieving the purpose of shaping the rising and falling edges of the input current waveform.

[0111] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for braking a speed measuring wheel during wafer cleaning, characterized in that, An electromagnetic brake is applied to a speed measuring wheel equipped with an electromagnetic brake. The electromagnetic brake includes a stator, a rotor, and a coil winding. The stator has a friction plate on its side near the rotor. The rotor is fixedly connected to the shaft of the speed measuring wheel. The method includes: passing a first pulse current through the coil winding to magnetize it, attracting the rotor to move towards the stator until it contacts the friction plate for friction braking; passing a second pulse current through the coil winding to demagnetize it, disengaging the rotor from the friction plate and releasing the braking restriction on the speed measuring wheel; wherein the electromagnetic brake also includes a sealing ring sleeved on the outside of the stator and the rotor, the sealing ring being fixedly connected to the stator and movably connected to the rotor, used to prevent cleaning fluid for cleaning wafers from entering the interior of the electromagnetic brake; a heat dissipation hole is provided on the side of the sealing ring, and a blocking element is provided at the outlet of the heat dissipation hole near the wafer to prevent cleaning fluid for cleaning wafers from entering the heat dissipation hole; the diameter of the heat dissipation hole near the shaft is larger than the diameter of the hole away from the shaft.

2. The braking method for the speed measuring wheel according to claim 1, characterized in that, The step of passing a first pulse current through the coil winding to magnetize the coil winding and attract the rotor to move closer to the stator until it contacts the friction plate for friction braking includes: passing a first pulse current through the coil winding to generate a magnetic field that attracts the rotor, causing the rotor to contact and rub against the friction plate, and stopping the speed measuring wheel from rotating; stopping the passage of the first pulse current through the coil winding, and maintaining the current braking state of the rotor.

3. The braking method for the speed measuring wheel according to claim 2, characterized in that, The step of passing a second pulse current through the coil winding to demagnetize the coil winding, disengaging the rotor from the friction plate, and releasing the braking restriction on the speed measuring wheel includes: passing a second pulse current through the coil winding to demagnetize the coil winding, resetting the rotor and disengaging it from the friction plate; wherein the first pulse current and the second pulse current have opposite current directions; stopping the passage of the second pulse current through the coil winding, maintaining the rotor in its current reset state, and the speed measuring wheel rotating synchronously with the wafer.

4. The braking method for the speed measuring wheel according to claim 1, characterized in that, The speed measuring wheel braking method further includes: real-time detection of the thickness and temperature of the friction plate, logical comparison of the detection results with preset alarm values, and issuance of corresponding alarm information.

5. The braking method for the speed measuring wheel according to claim 1, characterized in that, The speed measuring wheel braking method further includes: real-time detection of the magnetic strength of the magnetic field generated by the coil winding, and adjustment of the magnitude of the first pulse current or the second pulse current supplied to the coil winding based on the detection result.

6. A wafer cleaning apparatus, characterized in that, The wafer cleaning apparatus is used to implement the speed measuring wheel braking method according to any one of claims 1 to 5, comprising: a housing, the interior of which is used to accommodate a wafer and provide space for wafer cleaning; a cleaning assembly including roller brushes located on both sides of the wafer, the roller brushes rotating along their axial direction to perform rolling scrubbing on the wafer surface; a driving assembly including a driving wheel and a speed measuring wheel in contact with the edge of the wafer, the driving wheel being used to limit and drive the wafer to rotate along its axis in a vertical plane, the speed measuring wheel being passively rotated under the drive of the wafer; wherein, the speed measuring wheel is driven to connect to an electromagnetic brake, and a first current is applied to the electromagnetic brake. A pulse current brakes the speed measuring wheel, or a second pulse current releases the brake on the speed measuring wheel; the electromagnetic brake also includes a sealing ring sleeved on the outside of the stator and the rotor, the sealing ring being fixedly connected to the stator and movably connected to the rotor, used to prevent cleaning fluid used for cleaning the wafer from entering the interior of the electromagnetic brake; heat dissipation holes are provided on the side of the sealing ring, and a blocking element is provided at the outlet of the heat dissipation hole near the wafer, used to prevent cleaning fluid used for cleaning the wafer from entering the heat dissipation hole; the hole spacing on the side of the heat dissipation hole near the rotating shaft is greater than the hole spacing on the side away from the rotating shaft.

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