Large-size wafer wide-area laser polishing device and polishing method

Abstract

A large-area laser polishing apparatus and method for large-size wafers includes a laser, a collimating lens, an intermediate reflecting mirror, a semi-transparent mirror, a focusing lens, a CCD autofocusing system, an end reflecting mirror, an air jet, and a processing motion platform. The collimating lens is vertically positioned, the intermediate reflecting mirror and the semi-transparent mirror are parallel to each other and at a 45-degree angle to the horizontal plane, and the end reflecting mirror receives and reflects the laser beam from the focusing lens, causing the laser beam to be obliquely incident on the surface to be processed. The CCD autofocusing system dynamically adjusts the angle of the end reflecting mirror to adjust the focal position of the laser beam, ensuring that the laser beam is always accurately focused at the processing location. The air jet provides auxiliary gas during processing and blows away slag and oxides generated during polishing. This invention overcomes the dual limitations of short working distance of traditional focusing lenses and large focal depth of galvanometers, solving the problem of not being able to simultaneously achieve processing accuracy and processing size, and improving processing quality.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and in particular to a large-size wafer wide-area laser polishing device and polishing method. Background Technology

[0002] Laser polishing utilizes the high energy density of a laser beam, focusing it directly onto the surface of a part to create a high-temperature, high-pressure zone that instantly melts the surface. By absorbing laser energy and altering surface tension, the melting or vaporization rate reaches the millisecond level. Because the laser's effects on surface structure do not affect the material's inherent properties, it achieves highly efficient and precise polishing, making it suitable for the precision machining of hard and brittle materials.

[0003] When polishing large-size wafers, traditional laser polishing techniques using fixed-focal-length focusing lenses or high-magnification objectives often have limitations in terms of polishing accuracy and efficiency, and it is often impossible to achieve both simultaneously. If a fixed-focal-length focusing lens is used to pursue processing efficiency, the short working distance of the traditional focusing lens limits the processing area of ​​the workpiece. This presents significant limitations in adapting to workpieces of varying thicknesses, shapes, and complex surface conditions, making it difficult to achieve uniform and high-quality polishing results for large-area workpieces. In particular, frequent adjustments to the focal length or processing parameters are required during polishing, and manual replacement of optical components or adjustment of the focusing lens position are necessary. This is not only time-consuming but also prone to introducing errors, affecting the consistency and reliability of the processing. Using ultra-high-magnification lenses for vertical polishing places high demands on equipment, results in slow polishing speeds, and offers very limited improvement in processing dimensions. Polishing using long-focal-length lenses with oblique incidence typically employs a galvanometer for workpiece polishing or rust removal. However, the large depth of field of the galvanometer beam leads to low processing accuracy and poor polishing precision. Therefore, the aforementioned processing methods often suffer from the problem of not being able to achieve both processing accuracy and processing size, making it difficult to meet the processing requirements of large-size, high-precision workpieces. Moreover, when performing large-area wafer polishing, the complexity of the optical system often leads to increased costs and maintenance difficulties. At the same time, there is a lack of effective anti-collision mechanisms to reduce the risk of workpiece damage, and there are also problems such as insufficient accuracy of the autofocus mechanism and insufficient motion response speed of the workpiece motion platform that urgently need to be solved. Summary of the Invention

[0004] The purpose of this invention is to overcome the limitations of processing range caused by the fixed focal length of traditional laser focusing lenses, and the insufficient efficiency of high-magnification objective lens vertical laser processing when handling large areas or complex shapes. This invention provides a wide-area laser polishing apparatus for large-size wafers, and a polishing method using this apparatus. This laser processing apparatus, through its end-reflection obliquely incident laser beam design, allows the wafer platform's trajectory algorithm to coordinate with the laser beam movement. Combined with a CCD autofocus system and a trial process, it achieves high-precision and high-efficiency laser polishing of ultra-large wafers. This method meets the demands of the semiconductor industry for high-precision, high-adaptability, and automated processing, and is particularly suitable for polishing large-area, ultra-large wafers.

[0005] This invention is achieved through the following technical solution:

[0006] A large-area laser polishing apparatus for large-size wafers includes a mounting frame, a laser, a collimating lens, an intermediate reflector, a semi-transparent mirror, a focusing lens, a CCD autofocus system, an end reflector, an air jet, a first Z-axis moving module, and a processing motion platform. The laser, collimating lens, intermediate reflector, semi-transparent mirror, focusing lens, CCD autofocus system, end reflector, and air jet are all mounted on the mounting frame, which is mounted on the first Z-axis moving module. The laser generates a vertically downward laser beam. The collimating lens, intermediate reflector, semi-transparent mirror, focusing lens, and end reflector... The focusing mirrors are arranged sequentially along the laser beam path. The collimating mirror is horizontally positioned to shape the original laser beam generated by the laser into a vertical parallel laser beam. The intermediate reflecting mirror and the semi-transparent semi-reflecting mirror are parallel to each other and at a 45-degree angle to the horizontal plane. After the vertical laser beam is reflected sequentially by the intermediate reflecting mirror and the semi-transparent semi-reflecting mirror to change its beam path, it becomes a vertical beam again and reaches the focusing mirror. The focusing mirror is horizontally positioned to focus the vertical laser beam from the semi-transparent semi-reflecting mirror. The end reflecting mirror is tilted to receive the laser beam from the focusing mirror and reflect the laser beam, so that the laser beam is obliquely incident on the surface of the wafer to be processed.

[0007] The CCD autofocus system includes a vision sensor that captures images of the area to be processed on the wafer using high-resolution imaging technology. The vision sensor includes an LED light source positioned directly above a semi-transparent mirror. The semi-transparent mirror reflects the laser beam while allowing light from the LED light source to pass through and ultimately reach the surface of the wafer to be processed, providing illumination for the vision sensor to accurately identify the condition of the wafer surface. The CCD autofocus system is connected to a focusing lens and an end mirror, and dynamically adjusts the angle of the end mirror and the distance between the end mirror and the focusing lens based on the image information of the surface to be processed on the wafer. This adjusts the focal point of the laser beam, ensuring that the laser beam is always accurately focused on the processing location, thereby improving polishing accuracy and adapting to wafers of different areas and thicknesses. The processing motion platform is located below the end mirror and is used to fix the wafer to be processed and move the wafer to cooperate with laser processing.

[0008] The jet nozzle of the jet is directed towards the area of ​​the wafer to be processed. The jet is used to provide auxiliary gas during the processing to help improve polishing efficiency and quality. At the same time, the slag and oxides generated during polishing are effectively blown away by the auxiliary gas, preventing the slag from re-solidifying on the polished surface or causing damage to the wafer.

[0009] By adjusting the angle of the end reflector, the laser beam can be incident obliquely onto the wafer surface at a certain angle. This helps to effectively adjust the distance to workpieces with different surface shapes to adapt to the polishing of large-area and ultra-large wafers. The role of the end reflector is not only to change the optical path, but also to control the laser energy acting on the workpiece surface, thereby improving the polishing quality. Simply adjusting and changing the angle of the optical path cannot achieve effective polishing of the processed surface.

[0010] Furthermore, the CCD autofocus system also includes a processor and a control actuator. The processor is used to process and analyze the images captured by the vision sensor using an integrated image processing algorithm, and transmit commands to the control actuator and the first Z-axis moving module. The first Z-axis moving module drives the mounting frame to move up and down according to the commands to adjust the distance between the laser focus and the wafer to be processed. The control actuator includes a second Z-axis moving module and a first swing module disposed on the mounting frame and connected to the end reflector. The second Z-axis moving module is used to drive the end reflector to move up and down according to the commands, and the first swing module is used to drive the end reflector to rotate according to the commands to adjust the position and angle of the end reflector and adjust the relative position of the laser focus.

[0011] Furthermore, the processing motion platform includes an X-axis linear motion module, a Y-axis motion module, a second swing module, a rotation module, and a processing table. The Y-axis motion module is disposed on the X-axis linear motion module, the second swing module is disposed on the Y-axis motion module, the rotation module is disposed on the second swing module, and the processing table is disposed on the rotation module. The processing table is used to fix the wafer to be processed. The second swing module is used to drive the processing table and the wafer to be processed on it to tilt relative to the vertical direction. The rotation module is used to drive the processing table and the wafer to be processed on it to rotate around its vertical central axis. The rotation speed of the rotation module can be set to 300-600 rpm, wherein the rotation speed can vary according to a certain functional relationship, and the speed of the linear motion module can be controlled to 10 m / s.

[0012] Furthermore, the second oscillation module includes an oscillation motor, an oscillation plate, and a swing arm. One end of the oscillation plate is perpendicularly connected to the output shaft of the oscillation motor, and the other end is perpendicularly connected to the swing arm. The rotation module includes a rotary motor mounted on the swing arm. The processing table is driven and connected to the rotary motor, and the rotation axis of the processing table is perpendicular to the rotation axis of the oscillation motor. A vacuum chuck is provided on the top of the processing table for fixing the wafer to be processed by vacuum adsorption.

[0013] Furthermore, the end reflector receives the laser beam emitted from the focusing lens and precisely adjusts the laser beam reflection angle to achieve oblique incidence of the laser beam; the end reflector ensures that the laser beam is obliquely incident on the surface of the wafer to be processed at an angle of 15°-45°. The surface of the reflector is coated with a high-reflectivity coating; the high-reflectivity coating can be a multilayer dielectric film or a metal coating.

[0014] Furthermore, the jet generator also includes an air inlet and an air outlet, which are respectively located at both ends of the air pipe. The air inlet is used to connect to a gas supply device, and the air outlet is a converging conical nozzle structure. The gas injection flow rate of the jet generator ranges from 5-20 L / min, and the auxiliary gas is oxygen, nitrogen, carbon dioxide, or air. During laser polishing, the jet generator also prevents spatter from damaging or contaminating the lens, keeping the reflective surface clean.

[0015] Furthermore, the mounting bracket is used for mounting and supporting, enclosing the internal components and providing fixation and protection against external environmental influences. The mounting bracket is equipped with clamps for securely holding the jet, ensuring precise positioning and stability during laser polishing. The jet is connected to the mounting bracket via the clamps. The clamp includes a clamp body and several hinged joints connected front and rear. The clamp body is connected to the mounting bracket via these hinged joints, giving the clamp a multi-axis shape, allowing it to hold the jet from multiple directions and adjust the jet's mounting angle on the mounting bracket. The absolute value of the clamp's repeatability is less than 0.005 mm.

[0016] Furthermore, the mounting frame adopts a modular structure, consisting of multiple housing modules, including a collimation module, a central reflection module, a CCD focusing module, a focusing module, and an end reflection module. The collimation module and the CCD focusing module are fixed above the central reflection module, the focusing module is fixed below the central reflection module, and the end reflection module is located below the focusing module. The collimating lens is fixed in the collimation module, the intermediate reflector and the semi-transparent mirror are located in the central reflection module, the focusing lens is located in the focusing module, the jet is fixed outside the focusing module, and the end reflection is located in the end reflection module, facilitating the installation, replacement, and maintenance of the components. The mounting frame is also equipped with heat dissipation channels to ensure that each component maintains a suitable temperature during long-term operation or high-power operation.

[0017] The mounting frame is connected to the first Z-axis moving module via a mounting plate. The first Z-axis moving module is used to drive the mounting frame and the component (laser processing head) mounted on the mounting frame to move up and down according to control commands.

[0018] Furthermore, the laser is a continuous laser or a quasi-continuous laser, the pulse half-width of the laser beam emitted by it is 1ms, the power range of the laser beam is 100-1000W, and the energy distribution of the continuous laser generated by the laser is Gaussian.

[0019] Furthermore, the laser is connected to the collimating lens via a pluggable fiber optic connector. The pluggable fiber optic connector facilitates quick replacement or connection of different lasers. The fiber optic connector couples the laser energy from the laser into the optical fiber, and then transmits it from the optical fiber to the polishing head, where it first enters the collimating lens.

[0020] Furthermore, the collimating lens can reduce the influence range of the focused spot, making the energy more concentrated and improving the polishing accuracy; the collimating lens is made of a high thermal stability material, which can resist the heat generated during laser processing and maintain the stability of the lens shape and refractive index. The high thermal stability material is K9 glass or quartz glass.

[0021] The focusing lens can reduce the loss and distortion of the laser beam during transmission and focusing; the focal length of the focusing lens is approximately 25-200mm, and the lens diameter is 25-100mm.

[0022] A method for wide-area laser polishing of large-size wafers, using the aforementioned wide-area laser polishing apparatus for large-size wafers, includes the following steps:

[0023] S1: Fix the wafer to be processed on the processing motion platform, move the processing motion platform to the processing area and position it, ensure that the jet is in place, and adjust the direction of the jet so that its jet direction is directly facing the wafer;

[0024] S2: Start the CCD autofocus system to acquire wafer surface information. Adjust the focus position by adjusting the mounting bracket height, the position and angle of the end reflector, and focus on the wafer surface. Adjust the focus to the highest point of the wafer surface. Set the initial working parameters of the laser processing device according to the wafer material and thickness. The initial working parameters include laser power, polishing speed and initial focal length.

[0025] S3: Perform local polishing tests at the edge of the wafer to verify the suitability of the current polishing parameters. Based on the test feedback, use the built-in control software to further adjust the laser parameters to ensure the optimal polishing effect.

[0026] S4: Start the laser processing device and drive the laser beam to move autonomously along the preset path to perform large-area polishing on the wafer. At the same time, the wafer is moved linearly, oscillated and rotated under the drive of the processing motion platform to achieve progressive thinning and polishing of the wafer. During the operation, the CCD automatic focusing system adjusts the focus position in real time according to the real-time working conditions of the wafer surface by adjusting the height of the mounting bracket and the position and angle of the end reflector.

[0027] S5: After polishing is completed, the polishing quality of the wafer is evaluated, such as edge roughness and polishing precision. The laser is then turned off and the polishing mode is exited. The wafer is then removed and post-processed.

[0028] The beneficial effects of this invention are as follows:

[0029] (1) By setting a movable reflector at the end of the optical path, the present invention can effectively widen the processing area by obliquely incident laser onto the processing surface, allowing the laser beam to cover a larger area, meeting the processing needs of large workpieces or complex shapes, and realizing wide-area processing; at the same time, this oblique incident method also allows the laser energy to be more evenly distributed in a larger processing area, which can avoid deep processing during the polishing process, avoid the decrease in polishing accuracy caused by the increase in the material removal depth of the laser beam, and even the appearance of dark cracks, thereby improving the surface polishing accuracy. By reducing the reflection and scattering of laser energy, a smoother polishing edge and higher energy utilization rate can be achieved, which is suitable for polishing large-area wafers. Compared to traditional high-precision polishing processes that require ultra-high magnification focusing lenses or galvanometers, this method can simultaneously increase the size of the workpiece and improve polishing accuracy. However, when traditional laser beams are used for vertical polishing, the energy variation along the axial direction around the focal point leads to a larger processing dimension in the depth direction. Especially when high-precision polishing requires increased energy, the depth to which the laser beam removes material also increases, resulting in a significant decrease in surface polishing accuracy and even the appearance of dark cracks. Moreover, ultra-high magnification focusing lenses have high equipment requirements, limited improvement in the processing area, and reduced processing speed. On the other hand, polishing by directly obliquely incident the laser beam to ensure concentrated removal of a very small unit depth in a single pass is limited by the short working distance of traditional focusing lenses, which can only process workpieces with a limited area. Galvanometers, with their natural telecentric oblique incidence, can process large workpieces, but when using galvanometers for polishing or rust removal, the large depth of field of the beam results in poor polishing accuracy. Therefore, these traditional methods cannot achieve both high processing size and high processing accuracy.

[0030] (2) In addition, due to the presence of the end reflector, the entire laser polishing head can be higher than the workpiece surface. That is, during the processing, the laser polishing head is located above the workpiece and will not be directly facing the workpiece. This design cleverly avoids the distance between the processing head and the workpiece being too close or at the same height or even lower than the workpiece. This avoids wear and damage to the focusing lens caused by material splashing. It also reduces unnecessary vibration, displacement and heat caused by the distance being too close, and reduces the impact on processing accuracy and stability caused by these factors. Non-contact long-distance processing also means a longer polishing head life and lower maintenance costs.

[0031] (3) The CCD automatic focusing system is adopted, eliminating the tedious process of manually changing the reflector and ensuring that the laser beam is always accurately focused on the wafer surface in the best state. Regardless of changes in material, thickness, or unevenness or bumps on the wafer surface, the precision and consistency of the polishing process can be maintained, thereby significantly improving the processing accuracy and yield.

[0032] (4) A semi-reflective mirror is set in the laser optical path. While reflecting the laser and changing the optical path, it can provide illumination conditions for the visual sensing part of the CCD autofocus system. The visual sensing part does not need to be equipped with an additional light source, which improves the integration level of the system.

[0033] (5) The jet generator can provide auxiliary gas for the polishing process, reduce oxidation and discoloration during the processing, and improve the processing quality. On the other hand, it can effectively remove the slag and heat generated during the polishing process, prevent the slag from resolidifying on the polishing surface or causing damage to the wafer, and prevent spatter from damaging or contaminating the lens, keeping the mirror surface clean and improving polishing efficiency.

[0034] (6) Practice has proven that the final wafer product has a polishing roughness of less than 300nm, a height difference of less than 10μm, high polishing precision, and a wafer polishing speed of up to 30min / wafer, which is high processing speed.

[0035] (7) The modular design allows for flexible combination of components to meet different functional requirements and is also conducive to the installation, replacement and maintenance of equipment.

[0036] Therefore, the laser polishing head device of the present invention breaks through the dual limitations of short working distance of traditional focusing mirror and large focal depth of galvanometer, and solves the problem of not being able to achieve both processing accuracy and processing size. It not only realizes automation and intelligence in technology, improving production efficiency and processing quality, but also demonstrates excellent flexibility, safety and high efficiency in practical applications. It meets the stringent requirements of modern industry for precision processing, such as the requirements of the semiconductor industry for high precision, high efficiency and automated production. It has broad market application potential and is expected to promote the development of industrial manufacturing towards a higher level of automation and intelligence. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of the laser processing device according to an embodiment of the present invention.

[0038] Figure 2 This is an exploded view of the laser processing apparatus according to an embodiment of the present invention.

[0039] Figure 3 This is a partial structural schematic diagram of the laser processing device according to an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the structure of the laser processing device according to an embodiment of the present invention.

[0041] Figure 5 This is a schematic diagram of the processing motion platform in the laser processing apparatus of this invention.

[0042] Figure 6This is an enlarged schematic diagram of a portion of the processing motion platform in the laser processing apparatus of this invention.

[0043] Figure 7 This is a partial side view of the processing motion platform in the laser processing apparatus of this invention.

[0044] Figure 8 This is a schematic diagram of another embodiment of the processing motion platform in the laser processing apparatus of the present invention.

[0045] Figure 9 This is a schematic diagram of the CCD automatic focusing system and control system in the laser processing apparatus of this invention.

[0046] Figure 10 This is a flowchart of a laser processing method according to an embodiment of the present invention.

[0047] Reference numerals: 1-Laser; 2-Collimating lens; 3-Intermediate reflector; 4-Semi-transparent and semi-reflective mirror; 5-Focusing lens; 6-End reflector; 7-Mounting bracket; 8-Jet; 9-Clamp; 10-CCD autofocus system; 11-Power interface; 12-Signal interface; 13-Mounting plate; 14-Laser beam; 15-Wafer; 16-LED beam; 17-Processing motion platform; 71-Collimating module; 72-Intermediate reflector module; 73-Focusing module; 74-End reflector module; 75-CCD autofocus module; 81-Jet pipe; 82-Air inlet; 83-Jet nozzle; 91-Hinge joint; 92-Clamp body; 171-X-axis linear motion module; 172-Y-axis motion module; 173-Oscillating motor; 174-Oscillating plate; 175-Swing arm; 176-Rotating motor; 177-Processing table; 178-Vacuum chuck. Detailed Implementation

[0048] This invention proposes an innovative large-area laser polishing device and method for large-size wafers, aiming to achieve laser thinning and polishing of ultra-large-size hard and brittle materials. This device overcomes the size limitations of traditional laser focusing technology. Its core innovation lies in solving the problems of conventional focused laser beams being unable to move over a large range due to size limitations and requiring frequent lens changes for different scenarios. This device combines the advantages of laser focusing mirrors and high-speed galvanometers, employing end-reflection and integrating a CCD autofocus system for rapid focus positioning. By controlling key parameters such as laser power, frequency, pulse width, and focus position, it achieves efficient and precise thinning and polishing of wafers. Specifically:

[0049] A large-area laser polishing device for wafers, such as Figures 1 to 4The system includes a mounting frame 7, a laser 1, a collimating lens 2, an intermediate reflector 3, a semi-transparent mirror 4, a focusing lens 5, a CCD autofocus system 10, an end reflector 6, an air jet 8, a first Z-axis moving module (not shown in the figure), and a processing motion platform 17. The laser 1, collimating lens 2, intermediate reflector 3, semi-transparent mirror 4, focusing lens 5, CCD autofocus system 10, end reflector 6, and air jet 8 are all mounted on the mounting frame 7, which is mounted on the first Z-axis moving module. The laser 1 generates a vertically downward laser beam 14. The collimating lens 2, intermediate reflector 3, semi-transparent mirror 4, focusing lens 5, and end reflector 6 are all mounted on the first Z-axis moving module. The focusing mirrors 6 are arranged sequentially along the laser beam path. The collimating mirror 2 is horizontally arranged to shape the original laser beam 14 generated by the laser 1 into a vertical parallel beam. The intermediate reflecting mirror 3 and the semi-transparent semi-reflecting mirror 4 are parallel to each other and at a 45-degree angle to the horizontal plane. After the vertical laser beam is reflected sequentially by the intermediate reflecting mirror 3 and the semi-transparent semi-reflecting mirror 4 to change the beam path, it becomes a vertical beam again and reaches the focusing mirror 5. The focusing mirror 5 is horizontally arranged to focus the vertical laser beam 14 from the semi-transparent semi-reflecting mirror 4. The end reflecting mirror 6 is inclined to receive the laser beam 14 from the focusing mirror 5 and reflect the laser beam 14, so that the laser beam 14 is obliquely incident on the surface of the wafer 15 to be processed.

[0050] The CCD autofocus system 10 includes a vision sensor, which captures images of the area to be processed on the wafer using high-resolution imaging technology. The vision sensor includes an LED light source positioned directly above the semi-transparent mirror 4. The LED light source generates an LED beam 16. The semi-transparent mirror reflects the laser beam while allowing the LED beam 16 to pass through and ultimately reach the surface of the wafer to be processed via the end mirror 6, providing illumination for the vision sensor to accurately identify the condition of the wafer surface. The CCD autofocus system is connected to the focusing mirror 5 and the end mirror 6, and dynamically adjusts the angle of the end mirror 6 and the distance between the end mirror 6 and the focusing mirror 5 based on the image information of the surface to be processed on the wafer. This adjusts the focal position of the laser beam 14, ensuring that the laser beam 14 is always accurately focused on the processing location, thereby improving polishing accuracy and adapting to wafers 15 of different areas and thicknesses. The processing motion platform 17 is located below the end mirror 6, used to fix the wafer 15 to be processed and to move the wafer 15 to cooperate with laser processing.

[0051] The machining motion platform 17 is connected to a drive device, which can drive the machining motion platform 17 to move. For example, it can move and rotate horizontally while simultaneously rotating vertically, or it can swing and rotate simultaneously. Horizontal movement can be driven by an electric cylinder, while swinging and rotation can be driven by a motor. The combination of these moving modules can realize the processing of different positions of the workpiece on the machining motion platform 17. The specific combination method can refer to the prior art and be set according to specific actual needs, while coordinating with the movement mode of the laser processing head. As one embodiment, such as Figures 5 to 8 The processing motion platform includes an X-axis linear motion module 171, a Y-axis motion module 172, a second swing module, a rotation module, and a processing table 177. The Y-axis motion module 172 is mounted on the X-axis linear motion module 171. The second swing module is mounted on the Y-axis motion module 172. The rotation module is mounted on the second swing module. The processing table 177 is mounted on the rotation module. The processing table 177 is used to fix the wafer to be processed. The second swing module is used to drive the processing table 177 and the wafer to be processed on it to tilt relative to the vertical direction. The rotation module is used to drive the processing table 177 and the wafer to be processed on it to rotate around its vertical central axis. The second swing module and the rotation module, in conjunction with a laser beam obliquely incident through an end reflector, can achieve polishing of large-size wafer surfaces, such as... Figure 9 The movement of the processing platform can be controlled by a control system. The rotation speed of the rotating module can be set to 300-600 rpm, where the rotation speed can vary according to a certain functional relationship, and the speed of the linear motion module can be controlled to 10 m / s.

[0052] The second oscillating module includes an oscillating motor 173, an oscillating plate 174, and an arm 175. One end of the oscillating plate 174 is perpendicularly connected to the output shaft of the oscillating motor 173, and the other end is perpendicularly connected to the arm 175. The rotating module includes a rotary motor 176, which is mounted on the arm 175. The processing table 177 is driven by the rotary motor 176, and the rotation axis of the processing table 177 is perpendicular to the rotation axis of the oscillating motor 173. A vacuum chuck 178 is provided on the top of the processing table 177, and the vacuum chuck 178 is connected to a vacuum generator for fixing the wafer to be processed by vacuum adsorption. The rotary motor 176 and the processing table 177 can be simultaneously mounted on the arm 175, and the output shaft of the rotary motor 176 is parallel to the rotation axis of the processing table (e.g., ...). Figure 6 ) or vertical (such as Figure 5 , Figure 8 The output shaft of the rotary motor 176 and the rotating shaft of the processing table 177 can be connected via gear transmission. The oscillating motor 173 drives the oscillating plate 174 to rotate in the vertical plane, thereby causing the swing arm 175 and the rotating module to oscillate in the vertical direction, such as... Figure 7 The rotary motor 176 drives the processing table 177 and the wafer to be processed on it to rotate around the central axis of the processing table 177.

[0053] The jet nozzle 83 of the jet generator 8 is directed towards the wafer to be processed area. The jet generator 8 is used to provide auxiliary gas during the processing to help improve polishing efficiency and quality. At the same time, the slag and oxides generated during polishing will be effectively blown away by the auxiliary gas to prevent the slag from re-solidifying on the polishing surface or causing damage to the wafer 15.

[0054] The specific steps are as follows:

[0055] First, the wafer 15 to be processed is securely fixed on the processing motion platform 17 using a fixture. According to the specific position of the wafer 15 and the processing requirements, a suitable mounting bracket 7 is selected and fixed to install the laser 1, and the power interface 11 and signal interface 12 are connected through a transmission line.

[0056] Then, based on specific processing requirements, appropriate collimating mirror 2, intermediate reflector 3, semi-transparent mirror 4, and focusing mirror 5 are selected to ensure optimal quality and focusing effect of the laser beam 14. During the laser processing preparation stage, gas is introduced into the jet generator 8 through the air inlet 82 to provide auxiliary gas for the processing, which helps to effectively remove slag and control the heat-affected zone during processing. After the laser generator 1 is started, the laser beam 14 is transmitted through the fiber optic connector and enters the collimating mirror 2 to begin its shaping and focusing process. The original laser beam 14 is shaped into a nearly parallel beam in the collimating mirror 2, and after being reflected by the intermediate reflector 3 and semi-transparent mirror 4 to change its optical path, it is further shaped by the focusing mirror 5 to improve the laser's accuracy and energy density.

[0057] Finally, guided by the end reflector 6, the laser beam 14 is obliquely incident on the surface of the wafer to be processed at a certain angle, achieving efficient laser oblique incidence processing. By adjusting the angle of the end reflector, the laser beam can be obliquely incident on the wafer surface at a certain angle. This helps to effectively adjust the distance to workpieces with different surface shapes to adapt to the polishing of large-area and ultra-large wafers. The role of the end reflector 6 is not only to change the optical path, but also to control the laser energy acting on the workpiece surface, thereby improving the polishing quality. Simply adjusting and changing the angle of the optical path cannot achieve effective polishing of the processed surface.

[0058] In one embodiment, the laser 1 is a continuous laser 1 or a quasi-continuous laser 1, and the pulse half-width of the laser beam 14 emitted by it is approximately 1 ms. The power range of the laser beam 14 is 100-1000W, and the energy distribution of the continuous laser generated by the laser 1 is Gaussian. The laser 1 is connected to the collimating lens 2 via a quick-connect fiber optic connector. The quick-connect fiber optic connector facilitates the rapid replacement or connection of different lasers 1. The fiber optic connector couples the laser energy from the laser 1 into the optical fiber, and then transmits it from the optical fiber to the polishing head, where it first enters the collimating lens 2.

[0059] As one implementation method, the collimating lens 2 can reduce the influence range of the focused spot, make the energy more concentrated, and improve the polishing accuracy. The collimating lens 2 is made of a high thermal stability material, which can resist the heat generated during laser processing and maintain the stability of the lens shape and refractive index. The high thermal stability material is K9 glass.

[0060] The focusing lens 5 can reduce the loss and distortion of the laser beam 14 during transmission and focusing; the focal length of the focusing lens 5 is approximately 25-200mm, and the lens diameter of the focusing lens 5 is 25-100mm.

[0061] The end reflector 6 receives the laser beam 14 emitted from the focusing lens 5 and precisely adjusts the reflection angle of the laser beam 14 to achieve oblique incidence of the laser beam 14. Therefore, the end reflector 6 is a key component for achieving oblique laser incidence. It not only reflects the laser beam 14 but also adjusts the incident angle of the laser beam 14 as needed, enabling efficient processing of large or complex shaped wafers. In one embodiment, the surface of the end reflector 6 is coated with a high-reflectivity coating; the high-reflectivity coating can be a multilayer dielectric film or a metal coating, preferably a dielectric film, which can reflect light of a specific wavelength and has good reflectivity. The end reflector 6 enables the laser to be obliquely incident on the wafer surface, with the incident angle of the laser beam 14 onto the surface of the area to be processed on the wafer being approximately 15°-45°.

[0062] As one implementation method, such as Figure 5 The CCD autofocus system 10 further includes a processor and a control actuator. The processor is used to process and analyze the images captured by the vision sensor using integrated image processing algorithms, such as... Figure 9The system transmits commands to the control actuator and the first Z-axis moving module. The first Z-axis moving module drives the mounting frame to move up and down according to the commands, adjusting the distance between the laser focus and the wafer to be processed. The control actuator includes a second Z-axis moving module and a first swing module mounted on the mounting frame 7 and connected to the end reflector 6. The second Z-axis moving module drives the end reflector 6 to move up and down according to the commands, and the first swing module drives the end reflector 6 to rotate according to the commands, adjusting the position and angle of the end reflector 6 and the relative position of the laser focus, ensuring that the laser beam 14 is always focused on the processing surface. Specifically, the CCD automatic focusing system controls the movement of the first Z-axis moving module through the control system. The first Z-axis moving module, the second Z-axis moving module, and the first swing module can all adopt existing structures or forms, such as the Z-axis moving module using an electric cylinder and the first swing module using a micro motor for driving; these will not be elaborated further here.

[0063] As one implementation method, such as Figure 3 The jet generator 8 further includes an air inlet 82 and a jet pipe 81. The air inlet 82 and the jet outlet 83 are respectively located at both ends of the jet pipe 81. The air inlet 82 is used to connect to a gas supply device, and the jet outlet 83 is a converging conical nozzle structure. The gas injection flow rate of the jet generator 8 ranges from 5 to 20 L / min. The auxiliary gas is oxygen, nitrogen, carbon dioxide, or air. The jet generator 8 also prevents spatter from damaging or contaminating the lens during laser polishing, keeping the reflective mirror surface clean.

[0064] Mounting bracket 7 encloses the internal components, providing fixation and protection against external environmental influences. The mounting bracket 7 is equipped with clamps 9 to securely hold the jet generator 8, ensuring precise positioning and stability of the jet generator 8 during laser polishing. The jet generator 8 is connected to the mounting bracket 7 via the clamps 9. Figure 3 The clamp 9 includes a clamp body 92 and several hinge joints 91 connected front and rear. The clamp body 92 is connected to the mounting frame 7 via the hinge joints 91. The structure of the hinge joints 91 makes the clamp 9 multi-axis, which can clamp the jet 8 from multiple directions, thereby adjusting the mounting angle of the jet 8 on the mounting frame 7. The absolute value of the repeatability of the clamp 9 is less than 0.005 mm.

[0065] In one embodiment, the mounting bracket 7 adopts a modular structure, consisting of multiple housing modules, including a collimation module 71, a central reflection module 72, a CCD focusing module 75, a focusing module 73, and an end reflection module 74. The collimation module 71 and the CCD focusing module 75 are fixed above the central reflection module 72, the focusing module 73 is fixed below the central reflection module 72, and the end reflection module 74 is located below the focusing module 73. The collimating lens 2 is fixed in the collimation module 71, the intermediate reflector 3 and the semi-transparent / semi-reflective mirror 4 are located in the central reflection module 72, the focusing lens 5 is located in the focusing module 73, the jet 8 is fixed outside the focusing module 73, and the end reflection 6 is located in the end reflection module 74, facilitating the installation, replacement, and maintenance of the components. The CCD focusing module 75 is equipped with a power interface 11 and a signal interface 12, used for connecting power and control signals, respectively.

[0066] The mounting bracket 7 is also provided with heat dissipation channels to ensure that each component maintains a suitable temperature during long-term operation or high-power operation. The mounting bracket 7 is connected to the first Z-axis moving module through the mounting plate 13. The first Z-axis moving module is used to drive the mounting bracket 7 and the components mounted on the mounting bracket 7 to move up and down as a whole according to control commands, so as to adapt to large-area processing of the wafer surface.

[0067] A wide-area laser polishing method employs the aforementioned large-size wafer wide-area laser polishing device, such as... Figure 6 This includes the following steps:

[0068] S1: Fix the wafer 15 to be processed on the processing table 177, move the processing motion platform to the processing area and position it, ensure that the jet 8 is in place, and adjust the direction of the jet 8 so that its jet direction is facing the wafer 15.

[0069] S2: Start the CCD autofocus system 10, acquire wafer surface information, adjust the focus position by adjusting the mounting bracket height, the position and angle of the end reflector, focus on the wafer surface, and adjust the focus to the highest point of the wafer surface; set the initial working parameters of the laser processing device according to the wafer material and thickness, including laser power, polishing speed and initial focal length.

[0070] S3: Perform local polishing tests at the edge of the wafer to verify the suitability of the current polishing parameters. Based on the test feedback, use the built-in control software to further adjust the laser parameters to ensure the optimal polishing effect.

[0071] Because this invention uses oblique laser incidence, this processing method is highly sensitive to the focal point. Whether the energy of the focused beam can effectively remove the material needs to be verified. Therefore, a small-area processing operation is required first. By subtly moving the wafer, the processing effect is observed to determine the error in the focal point position. Simultaneously, since the wafer edge is relatively fragile, the edge of the wafer is preferentially selected to verify whether the energy of the incident laser beam is appropriate, thereby ensuring the suitability of the polishing parameters.

[0072] S4: Start the laser processing device and drive the laser beam to move autonomously along a preset path to perform large-area polishing on the wafer. At the same time, the wafer is moved linearly, oscillated, and rotated under the drive of the processing motion platform to achieve progressive thinning and polishing of the wafer. During the operation, the CCD automatic focusing system can also adjust the focus position in real time according to the real-time working conditions of the wafer surface by adjusting the height of the mounting bracket and the position and angle of the end reflector. The rotation speed of the processing motion platform can be set to 300-600 rpm, where the rotation speed can be varied according to a certain functional relationship, and the speed of the linear movement module can be controlled to 10 m / s.

[0073] S5: After polishing is completed, the polishing quality of the wafer is evaluated, such as edge roughness and polishing precision. The laser is then turned off and the polishing mode is exited. The wafer is then removed and post-processed.

[0074] After processing is complete, the laser 1 and CCD autofocus system 10 are turned off, the fixture 9 is released, and the processed wafer is removed and inspected. Simultaneously, the processing area is cleaned to maintain a clean environment and ensure the equipment is in good working order, preparing for the next processing run.

[0075] In one embodiment, the aforementioned laser polishing process is achieved by obliquely incident a laser onto the wafer surface in nitrogen atmosphere; the laser 1 used is a continuous laser emitting a continuous laser. The laser parameters are: laser pulse half-width approximately 1 ms, power approximately 100 W, and the energy distribution of the continuous laser is Gaussian; the gas jet flow rate of the jet 8 is approximately 10 L / min; the jet angle of the jet 8 is approximately 30°; the angle at which the laser beam 14 is obliquely incident on the wafer surface via the reflector is approximately 45°; and the absolute value of the repeatability of the fixture 9 is approximately 0.005 mm. Testing has shown that the production speed can reach 30 min / wafer, meaning that from placing a wafer on the device to completion of processing, it takes only 30 minutes. The processed wafer surface is smooth and burr-free, with a polishing roughness of less than 300 nm, a height difference of less than 10 μm, good polishing effect, and standard dimensions.

[0076] The processing quality and efficiency of this embodiment are superior to those of Comparative Examples 1 and 2 described below. Specifically:

[0077] Comparative Example 1

[0078] The main difference between Comparative Example 1 and the above embodiments is that no end-reflector is used; instead, a conventional method of perpendicularly incident laser light onto the wafer surface is employed, while other processing parameters remain unchanged. While this design simplification may be sufficient in some cases, it exhibits limitations in several aspects.

[0079] First, using only perpendicular laser incidence limits the laser beam's direction of action, restricting its application to the wafer surface. This limitation makes it difficult to meet the processing requirements of large or complex-shaped wafers, leading to reduced processing efficiency. Furthermore, the lack of oblique incidence capability prevents the laser beam from flexibly adapting to different parts of the wafer, especially in applications requiring multi-angle or multi-directional processing.

[0080] Secondly, without the aid of a reflector, the operator may need to make frequent manual adjustments to change the position and angle of the laser beam. This not only increases the complexity of the operation but may also introduce additional errors due to manual adjustments, affecting processing accuracy and repeatability.

[0081] Furthermore, perpendicular incidence is less adaptable to irregularities on wafer surfaces. When processing wafers with uneven or bumpy surfaces, perpendicular incidence may not effectively address these variations, leading to decreased processing quality or even failure to complete the processing task.

[0082] In summary, although Comparative Example 1 is similar to the Embodiment in some basic aspects, its lack of an end-effector significantly limits its application range and processing capabilities. In contrast, the embodiments of the present invention, by integrating autofocus and end-effector technologies, provide a more efficient, flexible, and adaptable laser polishing solution capable of meeting diverse industrial processing needs.

[0083] Comparative Example 2

[0084] The main difference between Comparative Example 2 and the above embodiments is that it does not include an air jet, while other processing parameters remain consistent with the embodiments. This omission in configuration may cause a series of problems during laser polishing.

[0085] First, the lack of an air jet means that slag and oxides cannot be effectively removed during laser polishing. These residues can not only reduce polishing quality but also contaminate the end reflector, leading to increased equipment maintenance needs and processing interruptions.

[0086] Secondly, the absence of an auxiliary gas may expand the heat-affected zone of the material. This expanded heat-affected zone can adversely affect the microstructure and mechanical properties of the material, especially in the processing of heat-sensitive materials, potentially leading to a decline in material properties.

[0087] Furthermore, assist gases play a crucial role in laser processing by increasing the material removal rate, thus accelerating polishing. Devices lacking this acceleration mechanism experience slower processing speeds, consequently impacting overall production efficiency.

[0088] In summary, while this comparative example may still operate in some simple applications without the jetting device, it exhibits significant limitations in terms of processing quality, equipment maintenance, material property protection, and production efficiency. In contrast, the jetting device integrated in this embodiment not only optimizes the polishing process but also improves processing flexibility and efficiency, demonstrating a more comprehensive potential for industrial applications.

[0089] The above detailed description is a specific description of feasible embodiments of the present invention. These embodiments are not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included in the patent scope of this case.

Claims

1. A large-size wafer wide-area laser polishing device, characterized in that, The system includes a mounting frame, a laser, a collimating lens, an intermediate reflector, a semi-transparent mirror, a focusing lens, a CCD autofocus system, an end reflector, an air jet, a first Z-axis moving module, and a processing motion platform. The laser, collimating lens, intermediate reflector, semi-transparent mirror, focusing lens, CCD autofocus system, end reflector, and air jet are all mounted on the mounting frame, which is mounted on the first Z-axis moving module. The laser generates a vertically downward laser beam. The collimating lens, intermediate reflector, semi-transparent mirror, focusing lens, and end reflector... The laser beam is arranged sequentially along the laser path. The collimating mirror is horizontally positioned to shape the original laser beam generated by the laser into a vertical parallel laser beam. The intermediate reflecting mirror and the semi-transparent semi-reflecting mirror are parallel to each other and at a 45-degree angle to the horizontal plane. The vertical laser beam is reflected sequentially by the intermediate reflecting mirror and the semi-transparent semi-reflecting mirror before reaching the focusing mirror. The focusing mirror is horizontally positioned to focus the vertical laser beam from the semi-transparent semi-reflecting mirror. The end reflecting mirror is tilted to receive the laser beam from the focusing mirror and reflect the laser beam, so that the laser beam is obliquely incident on the surface of the wafer to be processed. The CCD autofocus system includes a vision sensor, which captures images of the area to be processed on the wafer using high-resolution imaging technology. The vision sensor includes an LED light source positioned directly above a semi-transparent mirror. The semi-transparent mirror reflects the laser beam while allowing the light from the LED light source to pass through and ultimately reach the surface of the wafer to be processed, providing illumination for the vision sensor's imaging. The CCD autofocus system is connected to a focusing lens and an end mirror, and dynamically adjusts the angle of the end mirror and the distance between the end mirror and the focusing lens based on the captured image information of the area to be processed on the wafer. This adjusts the focal point of the laser beam, ensuring it is focused on the processing location to accommodate wafers of different areas and thicknesses. The jet nozzle of the jet is directed towards the processing area on the wafer. The jet provides auxiliary gas during processing and removes processing residue. The processing motion platform is located below the end mirror, used to fix the wafer to be processed and move the wafer to cooperate with laser processing. The CCD autofocus system further includes a processor and a control actuator. The processor is used to process and analyze the images captured by the vision sensor using an integrated image processing algorithm, and transmits commands to the control actuator and the first Z-axis moving module. The first Z-axis moving module drives the mounting frame to move up and down according to the commands to adjust the distance between the laser focus and the wafer to be processed. The control actuator includes a second Z-axis moving module and a first swing module disposed on the mounting frame and connected to the end reflector. The second Z-axis moving module is used to drive the end reflector to move up and down according to the commands, and the first swing module is used to drive the end reflector to rotate according to the commands to adjust the position and angle of the end reflector and adjust the relative position of the laser focus. The collimating lens is made of K9 glass or quartz glass; the focal length of the focusing lens is in the range of 25-200mm, and the lens diameter is in the range of 25-100mm; the laser is a continuous laser or a pulsed laser, the pulse half-width of the emitted laser beam is 1ms, the power of the laser beam is in the range of 100-3000W, and the energy distribution of the continuous laser generated by the laser is Gaussian; the laser is connected to the collimating lens through a pluggable fiber optic connector, and the laser beam emitted by the laser enters the collimating lens through the fiber optic connector.

2. The large-size wafer wide-area laser polishing apparatus according to claim 1, characterized in that, The processing motion platform includes an X-axis linear motion module, a Y-axis motion module, a second swing module, a rotation module, and a processing table. The Y-axis motion module is disposed on the X-axis linear motion module, the second swing module is disposed on the Y-axis motion module, the rotation module is disposed on the second swing module, and the processing table is disposed on the rotation module. The processing table is used to fix the wafer to be processed. The second swing module is used to drive the processing table and the wafer to be processed on it to tilt relative to the vertical direction. The rotation module is used to drive the processing table and the wafer to be processed on it to rotate about its vertical central axis.

3. The large-size wafer wide-area laser polishing apparatus according to claim 2, characterized in that, The second oscillation module includes an oscillation motor, an oscillation plate, and an arm. One end of the oscillation plate is perpendicularly connected to the output shaft of the oscillation motor, and the other end is perpendicularly connected to the arm. The rotation module includes a rotary motor, which is mounted on the arm. The processing table is driven and connected to the rotary motor, and the rotation axis of the processing table is perpendicular to the rotation axis of the oscillation motor. A vacuum suction cup is provided on the top of the processing table for fixing the wafer to be processed by vacuum adsorption.

4. The large-size wafer wide-area laser polishing apparatus according to claim 1, characterized in that, The surface of the end reflector is coated with a high reflectivity coating, which is a multilayer dielectric film or a metal coating; the end reflector allows the laser beam to be incident at an angle of 15°-45° onto the surface of the wafer to be processed.

5. The large-size wafer wide-area laser polishing apparatus according to claim 1, characterized in that, The jet generator also includes an air inlet and a jet nozzle, which are respectively located at both ends of the jet pipe. The air inlet is used to connect to the gas supply equipment, and the jet nozzle is a concave cone nozzle structure. The gas injection flow rate of the jet generator is 5-20 L / min, and the auxiliary gas is oxygen, nitrogen, or air.

6. The large-size wafer wide-area laser polishing apparatus according to claim 1, characterized in that, The mounting frame is equipped with a clamp, and the jet is connected to the mounting frame through the clamp. The clamp includes a clamp body and several hinge joints connected front and rear. The clamp body is connected to the mounting frame through the several hinge joints. The structure of the several hinge joints connected front and rear makes the clamp have a multi-axis shape, thereby adjusting the installation angle of the jet on the mounting frame. The absolute value of the repeatability of the clamp is less than 0.005mm.

7. The large-size wafer wide-area laser polishing apparatus according to claim 1, characterized in that, The mounting frame adopts a modular structure, consisting of multiple housing modules, including a collimation module, a central reflection module, a CCD focusing module, a focusing module, and an end reflection module. The collimation module and the CCD focusing module are fixed above the central reflection module, the focusing module is fixed below the central reflection module, and the end reflection module is located below the focusing module. The collimating lens is fixed in the collimation module, the intermediate reflector and the semi-transparent mirror are placed in the central reflection module, the focusing lens is placed in the focusing module, the jet is fixed outside the focusing module, and the end reflection is located in the end reflection module. The mounting frame is connected to the first Z-axis moving module via a mounting plate. The first Z-axis moving module is used to drive the mounting frame and the components mounted on the mounting frame to move up and down according to control commands.

8. A method for wide-area laser polishing of large-size wafers, employing the wide-area laser polishing apparatus for large-size wafers as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1: Fix the wafer to be processed on the processing motion platform, move the processing motion platform to the processing area and position it, ensure that the jet is in place, and adjust the direction of the jet so that its jet direction is directly facing the wafer; S2: Start the CCD autofocus system to acquire wafer surface information. Adjust the focus position by adjusting the mounting bracket height, the position and angle of the end reflector, and focus on the wafer surface. Adjust the focus to the highest point of the wafer surface. Set the initial working parameters of the laser processing device according to the wafer material and thickness. The initial working parameters include laser power, polishing speed and initial focal length. S3: Perform local polishing tests at the edge of the wafer to verify the suitability of the current polishing parameters. Based on the test feedback, use the built-in control software to further adjust the laser parameters to ensure the optimal polishing effect. S4: Start the laser processing device and drive the laser beam to move autonomously along the preset path to perform large-area polishing on the wafer. At the same time, the wafer is moved linearly, oscillated and rotated under the drive of the processing motion platform to achieve progressive thinning and polishing of the wafer. During the operation, the CCD automatic focusing system adjusts the focus position in real time according to the real-time working conditions of the wafer surface by adjusting the height of the mounting bracket and the position and angle of the end reflector. S5: After polishing is completed, the polishing quality of the wafer is evaluated, the laser is turned off and the polishing mode is exited, and the wafer is removed and post-processed.

Images