Crystal surface processing equipment

Abstract

The utility model discloses crystal surface processing equipment. The equipment comprises a bearing module and a processing module, the processing module comprises a diamond wire unit, a cutting fluid pumping unit and an ultrasonic unit; the diamond wire unit can drive a diamond wire to move in the axial direction. The cutting fluid pumping unit can pump cutting fluid to the surface of the diamond wire, and the cutting fluid flows on the surface in an attached mode to form a flow beam. The ultrasonic unit is in contact with the cutting fluid and applies ultrasonic waves to the flow beam. The side surface and the datum plane of the hard crystal ingot are machined in a diamond wire cutting mode, in the wire cutting process, cutting fluid is pumped to form a flow beam, ultrasonic waves are directly applied to the flow beam through the ultrasonic unit, the focusing degree of ultrasonic energy is remarkably improved, cutting machining is assisted, and the machining efficiency is improved. The problems of machining errors and surface quality caused by direct application of ultrasound to the diamond wire are avoided, the problems of pollution and waste of hard material powder formed by grinding are also avoided, and the material utilization rate is remarkably increased.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor material preparation, in particular to a surface processing device for crystals. Background Art

[0002] Most semiconductor materials are hard materials. For example, silicon carbide single crystal materials are widely used in fields such as electric vehicles, photovoltaics, and radio frequency communications due to their wide bandgap width, high thermal conductivity, and high breakdown field strength, and are the most important third-generation semiconductor materials and devices.

[0003] Silicon carbide devices must go through very complex growth processes such as crystal growth, side surface processing, reference surface processing, slicing, polishing, epitaxy, ion implantation, and etching to be completed. Currently, physical vapor transport method or liquid phase method is generally used at home and abroad to grow silicon carbide ingots. After the side surface of the grown original silicon carbide ingot is processed, a silicon carbide rod with a regular circular geometric shape can be formed. Then, a reference surface that meets semiconductor standards is processed on the above-mentioned silicon carbide rod. Subsequently, the processed silicon carbide rod with a reference surface is cut into silicon carbide wafers with a certain thickness, and after grinding and polishing, qualified silicon carbide substrate products are manufactured. Through processes such as epitaxy and etching, silicon carbide devices are made and used in fields such as electric vehicles, 5G radio frequency communications, and consumer electronic products.

[0004] The side surface processing and reference surface processing of silicon carbide ingots are one of the essential processes for manufacturing silicon carbide substrates. Currently, high-precision grinding machines are commonly used in the industry. The outer circle of the side surface of the silicon carbide ingot is ground using a diamond grinding wheel with a Mohs hardness of ten. Since silicon carbide has a high hardness, Mohs 9.5, which is close to the hardness of diamond, the diamond grinding wheel consumes a large amount, and the processing efficiency is low. The side surface rolling and rounding processing time of a 6-inch silicon carbide ingot is about 8-9 hours. High-quality and ultra-fine diamond grinding wheels need to be imported, and the cost is very high.

[0005] In addition, during the rounding process of the silicon carbide grinding wheel, the diamond grinding wheel generates a large vertical mechanical extrusion force on the silicon carbide ingot, which easily causes the brittle silicon carbide ingot to crack and be scrapped.

[0006] The reference surface processing of silicon carbide is generally carried out using a diamond grinding wheel on a high-precision surface grinder. The length of the reference surface of a 6-inch standard ingot is 47.5 mm, and the processing time is about 3 hours. The cost is high and the efficiency is low. During the grinding process between the diamond grinding wheel and the silicon carbide ingot, all the silicon carbide materials that need to be ground off are ground into powder. The silicon carbide powder not only has no utilization value but also pollutes the environment, and the subsequent treatment cost of the silicon carbide powder is very high.

[0007] It can be seen that there are problems in the processing of the side surface and the reference surface of hard ingots such as silicon carbide at present, including inability to perform continuous processing, low processing efficiency, and pollution and waste of removed materials. There is an urgent need for a more advanced side surface and reference surface processing equipment and technology. Summary of the Utility Model

[0008] Aiming at the deficiencies of the prior art, the purpose of the present utility model is to provide a surface processing equipment for crystals.

[0009] To achieve the foregoing utility model purpose, the technical solutions adopted by the present utility model include:

[0010] The present utility model provides a surface processing equipment for crystals, including a loading module and a processing module. The loading module is used to load hard ingots, and the processing module can move relative to the loading module for processing the hard ingots.

[0011] The processing module includes a wire saw unit, a cutting fluid pump unit, and an ultrasonic unit;

[0012] The wire saw unit can drive the wire saw to move along the axial direction to process the hard ingot; the cutting fluid pump unit can continuously pump cutting fluid onto the surface of the wire saw and make the cutting fluid adhere and flow on the surface of the wire saw to form a flow bundle; the ultrasonic unit is in contact with the cutting fluid and is used to apply ultrasonic waves to the flow bundle.

[0013] Based on the above technical solutions, compared with the prior art, the beneficial effects of the present utility model at least include:

[0014] The processing equipment provided by the present utility model uses the wire saw cutting method to complete the processing of the side surface and the reference surface of the hard ingot. During the wire cutting process, cutting fluid is pumped to form a flow bundle, and the ultrasonic unit directly applies ultrasonic waves to the flow bundle, significantly improving the focusing degree of ultrasonic energy, assisting in completing the cutting process, and avoiding the processing errors and surface quality problems caused by directly applying ultrasonic waves to the wire saw.

[0015] In addition, by adopting the technical solution provided by the present utility model, the problems of pollution and waste of hard material powder formed by grinding are also avoided, and the material utilization rate is significantly improved.

[0016] The above description is only an overview of the technical solutions of the present utility model. In order to enable those skilled in the art to more clearly understand the technical means of the present application and implement it according to the content of the specification, the following is a detailed description with reference to the preferred embodiments of the present utility model and detailed drawings. Brief Description of the Drawings

[0017] Figure 1It is a schematic diagram of the state of the processing equipment provided by a typical embodiment of the present utility model before cutting starts;

[0018] Figure 2 It is a schematic diagram of the state of the processing equipment provided by a typical embodiment of the present utility model when cutting starts;

[0019] Figure 3 It is a schematic diagram of the state of the processing equipment provided by a typical embodiment of the present utility model when cutting the reference plane;

[0020] Figure 4 It is a schematic diagram of the state of the processing equipment provided by a typical embodiment of the present utility model when cutting the side surface;

[0021] Figure 5 It is a schematic diagram of the structure of the cut ingot provided by a typical embodiment of the present utility model;

[0022] Figure 6 It is a schematic diagram of the structure of the ingot residue obtained by cutting provided by a typical embodiment of the present utility model.

[0023] Explanation of reference numerals: 1, silicon carbide ingot; 2, diamond wire; 3, first ultrasonic generator; 4, second ultrasonic generator; 5, first liquid outlet channel; 6, second liquid outlet channel; 7, cutting fluid; 8, cutting fluid; 9, cutting fluid recovery device; 10, circulation drive mechanism; 11, precision moving platform; 12, ingot finished product; 12-1, side surface; 12-2, reference plane; 13, residue. Detailed implementation manners

[0024] In the prior art, the side surface and the reference plane of the original silicon carbide ingot are generally processed by a diamond grinding wheel on an external cylindrical grinding equipment and a surface grinder equipment in sequence. In the first step, the side surface of the original silicon carbide ingot is processed first, and the irregular side surface (generally 20-35 mm thick) of the grown original silicon carbide ingot is rounded into a circular side surface. In the second step, the required reference plane is processed on a surface grinder, and the length, direction, etc. of the reference plane should meet the corresponding semiconductor industry standards. The roundness processing time of the side surface of a 6-inch silicon carbide ingot is about 8-9 hours, and the reference plane requires 3 hours.

[0025] In view of the deficiencies in the prior art, the inventors of this case have proposed the technical solution of the present utility model through long-term research and a large number of practices. The following will further explain the technical solution, its implementation process and principle, etc.

[0026] In the following description, many specific details are set forth in order to provide a thorough understanding of the present utility model. However, the present utility model may be implemented in other ways different from those described herein. Therefore, the protection scope of the present utility model is not limited by the specific embodiments disclosed below.

[0027] Moreover, relational terms such as "first" and "second" are only used to distinguish one component or method step with the same name from another, and do not necessarily require or imply any such actual relationship or order between these components or method steps.

[0028] An embodiment of the present utility model first provides a surface processing device for a crystal, including a loading module and a processing module. The loading module is used to load a hard ingot, and the processing module can move relative to the loading module for processing the hard ingot. The processing module includes a wire saw unit, a cutting fluid pump unit, and an ultrasonic unit. The wire saw unit can drive the wire saw to move along the axial direction to process the hard ingot. The cutting fluid pump unit can continuously pump cutting fluid onto the surface of the wire saw and make the cutting fluid flow in an attached manner on the surface of the wire saw to form a fluid beam. The ultrasonic unit is in contact with the cutting fluid and is used to apply ultrasonic waves to the fluid beam.

[0029] The hard ingot processed by the present utility model typically takes a silicon carbide ingot as a representative, but this does not mean it is limited thereto. Ingots of other materials with similar hardness can also adopt the technical solution provided by the present utility model for processing the side surface and the reference surface. For example, in some implementation cases, it takes about 2.6 hours to process the side surface and the reference surface of a 6-inch silicon carbide ingot using the device of the present utility model, and about 3.5 - 4.5 hours for an 8-inch silicon carbide ingot. The production efficiency is increased by more than 50%. The remaining materials at the edge of the silicon carbide can also be recycled, improving the economic benefits of the industry.

[0030] Using a single diamond wire to cut out the required side surface and reference surface of a silicon carbide standard ingot at one time, replacing the traditional diamond grinding wheel for rounding the side surface of the original silicon carbide ingot and for surface grinding the reference surface of the original silicon carbide ingot, saves equipment investment, saves processing time, and improves production efficiency. During the processing, high-precision processing of the side surface and the reference surface can be completed with a single clamping, ensuring the geometric dimension accuracy of the processed ingot and improving the product yield.

[0031] In some typical examples, the original silicon carbide ingot described in the present utility model refers to the unprocessed silicon carbide ingot blank material grown by physical vapor transport method, liquid phase method, or flux method. In some typical examples, when the original silicon carbide ingot is fixed on the processing platform, the silicon carbide seed crystal bonding surface must be in firm contact with the processing platform, and the natural growth surface (non-planar) of the original silicon carbide ingot faces upward.

[0032] Moreover, the technical effects in other aspects of the present utility model also lie in that the side surface and the reference surface of the silicon carbide ingot can be processed at one time. During the processing, the high-precision processing of the side surface and the reference surface can be completed with one clamping, ensuring the geometric dimension accuracy of the processed ingot, improving the product yield, saving the processing time, saving the equipment investment, and increasing the production efficiency by more than 50%. For example, when using the method provided by the present utility model to process the side surface and the reference surface of a 6-inch silicon carbide ingot, the time is about 3 - 3.5 hours, and for an 8-inch silicon carbide ingot, the time is about 4.5 - 6 hours, with the production efficiency increased by more than 50%.

[0033] For the equipment for processing the side surface and the reference surface of the silicon carbide ingot and the method of using the same proposed by the present utility model, the principle is as follows: The outer circle and the reference plane of the silicon carbide ingot are cut by a single wire of a diamond wire. With the assistance of ultrasonic vibration, the cutting efficiency of the diamond wire is higher, the speed is faster, the surface finish of the cutting surface is higher, there is no dust and noise pollution during the cutting process, and the remaining silicon carbide after cutting can be reused as synthetic moissanite, having certain economic value.

[0034] The principle of ultrasonic vibration-assisted processing is to utilize the characteristics of high frequency and small amplitude of ultrasonic waves. Through an ultrasonic oscillator, mechanical vibration is converted into ultrasonic vibration, and the ultrasonic waves are transmitted to the surface of the workpiece or the surface of the cutting tool through a coupling member. During the transmission process, ultrasonic waves can generate a violent cavitation effect, that is, bubbles are generated during the vibration cycle. When the bubbles collapse within the cycle, the generated shock wave can generate a high-frequency and high-energy force. This force can change physical phenomena such as friction, deformation, and cutting force in the traditional processing process, thereby improving the processing efficiency and the cutting quality.

[0035] Although in the field of hard material processing, the processing method of cutting with a diamond wire assisted by ultrasonic waves has a long history, there are various different matching methods proposed in the prior art. For example, in some prior arts, some designed equipment is used to directly apply ultrasonic waves to the diamond wire body, and utilize the characteristic of the diamond wire to conduct ultrasonic waves to enable the ultrasonic waves to assist the cutting of the diamond wire, thereby improving the cutting efficiency and quality. However, through practice, the inventor of the present utility model found that this method is not suitable for processing high-hardness ingots, especially silicon carbide ingots, because the hardness of such ingots is already close to the hardness of the diamond particles on the surface of the diamond wire. In this case, directly applying ultrasonic waves to the diamond wire body will cause the problem of the position deviation of the diamond wire, resulting in problems such as over-standard processing dimensions or decreased surface quality. In most cases, among many different ultrasonic-assisted cutting methods, after several attempts by the inventor, often a diamond wire breaks or loses its sharpness before completing the processing of the ingot, which is also one of the difficulties in realizing the wire cutting processing of such hard silicon carbide ingots.

[0036] There are also some existing technologies that propose to use an immersion method to perform wire saw cutting assisted by ultrasound. The cutting process occurs in a container containing cutting fluid. By applying ultrasound to the cutting fluid in the container, the ultrasound acts indirectly on the cutting position, playing roles such as assisting in chip removal and increasing the cutting rate. However, similarly, the above method may produce better effects for ingots with slightly lower hardness, but for ultra-hard ingots such as silicon carbide, since the ultrasound is dispersed in the entire liquid phase, the energy of the ultrasound is not focused on the cutting position. Therefore, it is difficult to obtain a high ultrasonic power density, and thus it is impossible to effectively improve the cutting efficiency and the quality of the cut surface for such ultra-hard ingots.

[0037] The basic technical concept adopted by the present utility model is different from the above-mentioned existing technologies. It adopts the mode of flow beam ultrasound. By pumping cutting fluid along the wire saw, a flow beam is formed along the wire saw. On the one hand, it plays the roles of cooling and lubrication. On the other hand, the ultrasound is directly applied to the flow beam, so that the energy of the ultrasound is restricted by the flow beam without divergence and is concentrated on the cutting interface, effectively playing the role of increasing efficiency and improving quality. In addition, since the ultrasound is not directly applied to the wire saw body but is focused and conducted to the cutting interface through the liquid phase, it will not interfere with the translational movement of the wire saw, thus meeting the requirements of high-precision dimensional requirements and high cut surface quality. These effects cannot be achieved by the above two methods.

[0038] Regarding some other implementation details, in some embodiments, the wire saw moves along the gravity direction, and the liquid outlet channel of the cutting fluid pumping unit and the ultrasonic unit are arranged above the cutting position of the wire saw. There are multiple groups of the liquid outlet channel and the ultrasonic unit, and they are rotationally symmetrically distributed with the wire saw as the axis.

[0039] In some embodiments, the cutting fluid pumping unit includes a first liquid outlet channel and a second liquid outlet channel, the ultrasonic unit includes a first ultrasonic generator and a second ultrasonic generator. The first ultrasonic generator is arranged in cooperation with the first liquid outlet channel, the second ultrasonic generator is arranged in cooperation with the second liquid outlet channel. The first liquid outlet channel and the second liquid outlet channel are oppositely arranged with the wire saw as the axis, and the liquid outlet directions both point to the wire saw.

[0040] In the present utility model, preferably, the method of cooperating multiple groups of liquid outlet ports and ultrasonic units can form symmetric flow beams and ultrasonic waves around the wire saw, avoiding the influence of causing the wire saw to shift in one direction, thereby improving the cutting accuracy and the quality of the cut surface.

[0041] Not limited to two groups of liquid outlets and ultrasonic units with symmetric settings, multiple groups symmetrically distributed along the wire saw are acceptable; in addition, different liquid outlets can pump out the same liquid, such as pumping out a mixed liquid with auxiliary cutting and cooling effects, or can respectively pump out different liquids, for example, some liquids are for auxiliary cutting and some liquids only play a cooling role, and multiple liquids play corresponding roles together after mixing on the surface of the wire saw, and synchronously conduct ultrasonic waves.

[0042] In some embodiments, the distance between the outlet of the liquid outlet channel and the hard ingot is 3-5 mm. One of the key parameters in the present invention lies in the distance between the outlet of the liquid outlet channel and the hard ingot, and this distance is an important parameter for balancing the transmission efficiency of ultrasonic energy and cutting accuracy. If the distance is too small, it will cause physical collision between the surface of the ingot and the liquid outlet channel, damaging the ingot (reason: the surface of the grown ingot is a micro convex interface, rather than a strict plane). If the distance is too large, the transmission of ultrasonic waves will be affected, resulting in power loss and significantly reducing the auxiliary effect.

[0043] In some embodiments, the cutting fluid pumping unit further includes a cutting fluid recycler, which is arranged below the wire saw and is used to collect the cutting fluid in the flow beam and pump the collected cutting fluid to the liquid outlet channel.

[0044] In some embodiments, diamond particles are embedded on the surface of the wire saw, and the particle size of the diamond particles is 3-12 μm; the diameter change rate of the wire saw is below 2%.

[0045] As a typical example, in the present invention, the wire saw used can attach artificial diamond particles to the steel wire bus bar by sintering method or electroplating method. The diameter of the diamond particles is in the range of 3-12 μm, and the optimal diameter is 6-9 μm. The diameter of the wire saw is 0.45-0.90 mm. When the diameter of the wire saw is less than 0.45 mm, the cutting efficiency is low, the tensile resistance is small, and it is easy to break the wire. When the diameter of the wire saw is greater than 0.90 mm, the surface roughness of the rear surface and the reference surface after cutting is high, and the finish is poor, not meeting the quality standards. The optimal value of the wire saw diameter is 0.60-0.80 mm, and the tensile fracture strength is greater than 260 Newtons.

[0046] In some embodiments, the wire saw unit includes a circulating driving mechanism, and the wire saw cooperates with the circulating driving mechanism to move along its own axial direction under the drive of the circulating driving mechanism.

[0047] In some embodiments, the carrier module includes a precision moving platform having at least two degrees of freedom of movement. The precision moving platform includes a fixed part and a moving part. The hard ingot can be fixed on the moving part, and at least two of the degrees of freedom are perpendicularly crossed with the geometric axis of the hard ingot; moreover, the geometric axis of the ingot is parallel to the diamond wire at the cutting position.

[0048] In some embodiments, the precision moving platform includes a first track and a second track. The first track is fixedly arranged, and the second track is perpendicularly crossed with the first track and is slidably engaged with the first track and can be driven to translate along the extension direction of the first track; the hard ingot is fixedly arranged on the second track and can be driven to translate along the extension direction of the second track.

[0049] In addition, regarding the driving mode of the diamond wire, in some embodiments, the diamond wire is a closed-loop ring, and at this time, either unidirectional driving or reciprocating driving can be performed; or in some embodiments, the diamond wire is a linear type with non-connected ends, and the diamond wire unit can drive the diamond wire to perform linear reciprocating motion.

[0050] As a typical example, the wire running speed range of the diamond wire described in the present utility model is generally 40 - 65 m / s. When the wire running speed is lower than 40 m / s, the cutting efficiency is low and the service life of the cutting coolant is shortened. When the wire running speed is higher than 65 m / s, the wire is prone to breakage during the cutting process. The optimal wire running speed is 45 - 55 m / s.

[0051] The ultrasonic wave acts on the diamond wire, causing the diamond wire to vibrate with high frequency and small amplitude transversely, increasing the contact area. The ultrasonic frequency is 20 - 160 KHZ, the amplitude is 3 - 10 um, and the power is 100 - 800 W, and the power is continuously adjustable. When the amplitude is less than 3 um, the ultrasonic-assisted cutting effect is not obvious. When the amplitude is greater than 10 um, the wire is prone to breakage during the cutting process. The optimal value of the ultrasonic amplitude is 5 - 8 um, and the optimal ultrasonic frequency is 20 - 60 KHz.

[0052] In addition, by way of example, the cutting fluid includes water with a mass fraction of 40 - 65%, a surfactant with a mass fraction of 25 - 35%, and a corrosion inhibitor with a mass fraction of 10 - 35%; wherein, the corrosion inhibitor is an alkaline suspension.

[0053] The cutting coolant has three functions. The first is to assist the diamond wire in cutting and lubricating the silicon carbide material. The second is to carry away the cut silicon carbide powder. The third is to serve as a propagation medium for ultrasonic waves and transmit ultrasonic energy to the diamond wire. The cutting coolant can be used repeatedly for multiple times.

[0054] As some typical examples of the above technical solutions, the processes of the processing equipment and processing method provided by the present invention can be found in Figures 1-4 As shown, the device is used to process a silicon carbide ingot 1. The diamond wire 2 is made by attaching fine diamonds to a steel busbar through sintering or electroplating. The diamond particles have a diameter ranging from 3 to 12 μm, with an optimal diameter of 6 to 9 μm. The diamond wire has a tensile strength greater than 260 Newtons. The first and second ultrasonic generators 3 and 4 emit ultrasonic waves within a specific frequency range, enhancing the diamond wire's cutting performance. The first and second liquid outlet channels 5 and 6 are conduits for the cutting fluid.

[0055] The cutting fluids 7 and 8 output from different outlet channels merge to form a stream, which flows downward along the diamond wire 2. An exemplary cutting fluid may contain components such as pure water, a surfactant, and a corrosion inhibitor, wherein pure water accounts for 40-65% and the surfactant polyethylene glycol accounts for 25-35%. The surfactant has an excellent lubricating effect and can effectively prevent brittle cracking or scratches during the cutting process, and reduce the roughness of the silicon carbide side surface and reference surface. The corrosion inhibitor is mainly composed of alkaline suspended matter, accounting for 10-35%, and has a unique suspension property, which prevents the silicon carbide cutting powder from depositing and clogging the machine pipeline. All raw materials are environmentally friendly materials, and the wastewater after cutting is easy to treat; it has excellent lubrication, cooling, corrosion prevention, rust prevention and other functions. The roughness of the silicon carbide side surface reference surface after cutting is low, there are no wireless scratches, and it can extend the service life of the diamond wire.

[0056] The cutting fluid collector 9 is a power device capable of collecting and recycling cutting fluid, such as a container and a water pump. The container collects the flowing cutting fluid and then uses the pump to transport it to the outlet channel. The circulating drive mechanism 10 is a mechanical device that enables the diamond wire to circulate to cut the ingot. Optional drive modes include unidirectional circular drive (a circular diamond wire rotates in one direction) or reciprocating circular motion. The precision moving platform 11 is a mechanical platform that carries the silicon carbide ingot and is capable of precise movement in the X and Y directions perpendicular to gravity.

[0057] By using the above equipment and an appropriate cutting process, a finished ingot 12 and a residual material 13 can be obtained. The finished ingot 12 has a side surface 12-1 and a reference surface 12-2. The residual material 13 is a block material with excellent quality and can be used for gem processing.

[0058] Specific exemplary cutting process flow is as follows:

[0059] Step 1: Use a high-precision X-ray crystallography instrument to orient the base plane crystal direction [10-10] of the original silicon carbide ingot 1 after growth, and mark it on the original silicon carbide ingot, such as Figure 1As shown in the m direction. Fix the original grown silicon carbide ingot (with a diameter greater than 6 or 8 inches) that needs to be processed on the side surface and the reference plane on the precision moving platform 11 of the single-wire cutting equipment. The platform has the function of two-axis precision movement in the X direction and the Y direction and has a rotation function. The fixing method can use vacuum adsorption, high-viscosity glue or mechanical fixtures to ensure that the original silicon carbide ingot does not move relative to the processing platform during the cutting process. The growth surface of the original silicon carbide ingot faces upward, and the bottom surface of the original silicon carbide ingot bonded with the seed crystal contacts the processing platform.

[0060] Step 2: Install a diamond wire 2 with a diameter of 0.45 - 0.90 mm on the cutting equipment. The non-uniformity of the diamond wire diameter is less than 2%, and the maximum tensile strength is greater than 260 Newtons. The diamond wire can be made by electroplating or sintering methods. The diameter of the diamond particles is in the range of 3 - 12 μm, and the optimal diameter is 6 - 9 μm. If the diameter of the diamond particles is less than 3 μm, the cutting efficiency is low. If the diameter of the diamond particles is greater than 12 μm, the wire is prone to breakage during the cutting process, the cutting surface is rough, and defects such as chipping and cracking are likely to occur. Adjust the position of the processing platform loaded with the silicon carbide ingot so that the diamond wire is 2 - 5 mm outside the crystal edge position A in the [10 - 10] direction of the reference plane of the original silicon carbide ingot, ensuring that the diamond wire does not contact the silicon carbide ingot when starting to move at high speed, that is, the diamond wire is in an unloaded running state. The circulating wire speed of the diamond wire in the up and down direction is 40 - 65 m / s.

[0061] Step 3: Adjust the relative positions of the first ultrasonic generator 3 and the first liquid outlet channel 5, the second ultrasonic generator 4 and the first liquid outlet channel 6 on the equipment and the silicon carbide ingot on the platform. The appropriate static spacing is 3 - 5 mm. Start the diamond wire running movement function on the equipment. The diamond wire makes a high-speed up and down circular movement. The diamond wire only moves in the longitudinal Z-axis direction and does not move in the XY direction.

[0062] Step 4: Turn on the power supply of the ultrasonic generator to generate power ultrasound with a frequency of 20 - 160 KHZ. Turn on the circulating power supply of the cutting fluid for cooling the diamond wire. The cutting fluids 7 and 8 flow out at high speed through the first liquid outlet channel 5 and the second liquid outlet channel 6 respectively to cool the diamond wire 2. The ultrasound acts on the diamond wire after being transmitted through the media of the cutting fluids 7 and 8, causing the diamond wire to make a high-frequency micro-amplitude (3 - 10 μm) movement, which can increase the cutting efficiency by more than 30%.

[0063] Step 5: According to the standard size of the ingot finished product 12, program the movement trajectory of the processing platform. Control the movement of the processing platform by the equipment computer and slowly move the platform according to the designed movement trajectory at a movement rate of 0.03 - 0.05 mm / s. When the [10 - 10] edge of the reference plane of the silicon carbide ingot on the platform contacts the diamond wire moving at high speed, the cutting starts, as Figure 2 shown.

[0064] Step 6: After the cutting starts, the platform first moves slowly in the X direction. When the diamond wire cuts to the edge A ( Figure 2 ), the cutting of reference plane 12-2 starts. When the diamond wire cuts to the edge B ( Figure 2 ), the cutting of reference plane 12-2 is completed. When the platform starts to perform a combined movement in the X and Y directions, the diamond wire performs cutting processing on the side surface of the original ingot. When the diamond wire cuts to point C of the original ingot, the processing of ingot side surface 12-1 is completed, and the processed ingot finished product 12 is physically separated from the silicon carbide residue 13.

[0065] Step 7: Turn off the power supplies of ultrasonic generators 3 and 4 and the power supply of the cutting fluid supply system, turn off the power of the diamond wire running movement, move the platform in the X direction under computer control, move the platform and the ingot away from the diamond wire, unload the cut silicon carbide ingot and the silicon carbide corner residues after cutting and separation, and measure the processing quality of the silicon carbide side surface and the reference plane. The surface finish is 0.3 - 0.6um, meeting the quality standards.

[0066] Step 8: As Figure 5 shown, after the quality of the silicon carbide ingot is inspected and qualified, it is put into the next normal production process. As Figure 6 shown, the silicon carbide corner residues can be recycled and reused as synthetic moissanite to be processed into synthetic moissanite ornaments.

[0067] Based on the above process flow, the technical solution provided by the present utility model is suitable for processing the side surface and the reference plane of the original silicon carbide ingot with any diameter size, and can also process materials with any outer contour shape, not affected by the conductivity of silicon carbide, and can be suitable for conductive and semi-insulating silicon carbide ingots; it can also be suitable for processing the side surface and the reference plane of the original gallium nitride and aluminum nitride ingots, and is not affected by the crystal diameter size and limitation.

[0068] The diameter of the original silicon carbide is above 6 inches or above 8 inches, and is cut into a standard ingot with a diameter of 6 inches or 8 inches by this method. The thickness of the ingot is not restricted, generally 15 - 30mm, suitable for the original silicon carbide ingot with any thickness. The thicker the silicon carbide ingot, the more cost and production efficiency advantages the method of the present utility model has.

[0069] The processed side surface and reference plane have high surface finish, and the roughness value Ra is 0.3 - 0.6um, meeting the quality standards; compared with the traditional diamond grinding wheel processing, the production efficiency is increased by more than 50%; the silicon carbide residue after diamond wire cutting has the value of recycling and reuse, and can be made into synthetic moissanite ornaments, having certain economic value.

[0070] The technical solution of the present utility model will be further described in detail below through several embodiments in conjunction with the accompanying drawings. However, the selected embodiments are only used to illustrate the present utility model and do not limit the scope of the present utility model.

[0071] Embodiment 1

[0072] Step 1: Use a high-precision X-ray goniometer to orient the crystal orientation of the reference plane [10-10] of the as-grown raw silicon carbide ingot, and make markings on the raw silicon carbide ingot. Fix the as-grown raw silicon carbide ingot (diameter 160 mm, thickness 25 mm) that needs to be processed on the side surface and the reference plane on the processing platform of the single-wire cutting equipment. The platform has two-axis precision movement functions in the X and Y directions and has a rotation function. The fixing method can use vacuum adsorption, high-viscosity glue or mechanical fixtures to ensure that the raw silicon carbide ingot does not move relative to the processing platform during the cutting process. The growth surface of the raw silicon carbide ingot faces upward, and the bottom surface of the raw silicon carbide ingot bonded with the seed crystal contacts the processing platform.

[0073] Step 2: Install a diamond wire with a diameter of 0.45 mm on the cutting equipment. The non-uniformity of the diamond wire diameter is 1.5%, and the maximum tensile strength is 280 Newtons. The diamond wire can be made by electroplating, and the diameter of the diamond particles is 3 μm. Adjust the position of the processing platform loaded with the silicon carbide ingot so that the diamond wire is 4 mm outside the crystal edge position A in the direction of the reference plane [10-10] of the raw silicon carbide ingot, ensuring that the diamond wire does not contact the silicon carbide ingot when starting to move at high speed, that is, the diamond wire is in an unloaded running state. The circulating wire speed of the diamond wire in the up and down direction is 40 m / s.

[0074] Step 3: Adjust the relative positions of the two groups of ultrasonic generators and the liquid outlet channels on the equipment and the silicon carbide ingot on the platform. The appropriate static spacing is 3 mm. Start the diamond wire running movement function on the equipment. The diamond wire makes a high-speed up and down circular movement. The diamond wire only moves in the longitudinal Z-axis direction and does not move in the XY direction.

[0075] Step 4: Start the power supply of the ultrasonic generator to generate power ultrasonic waves with a frequency of 20 KHZ. Turn on the circulating power supply of the cutting coolant used to cool the diamond wire. The two cutting coolants flow out at high speed through different channels to cool the diamond wire. The ultrasonic waves act on the diamond wire after being transmitted through the cutting coolant medium, causing the diamond wire to make a high-frequency micro-amplitude (amplitude 10 μm) movement.

[0076] Step 5: According to the standard size of the target silicon carbide ingot, write the movement trajectory of the processing platform. Control the movement of the processing platform by the equipment computer, and slowly move the platform according to the designed movement trajectory at a movement rate of 0.05 mm / s. When the edge of the reference plane crystal orientation [10-10] of the silicon carbide ingot on the platform contacts the diamond wire moving at high speed, the cutting starts.

[0077] Step 6: After the cutting starts, the platform first moves slowly in the X direction. When the diamond wire cuts to the edge A ( Figure 2 ), the cutting of the reference plane starts. When the diamond wire cuts to the edge B ( Figure 2 ) of the original ingot reference plane, the cutting of the reference plane is completed. When the platform starts to perform a combined movement in the X and Y directions, the diamond wire performs cutting processing on the side surface of the original ingot. When the diamond wire cuts to the position of point C of the original ingot, the processing of the side surface of the ingot is completed. The processed silicon carbide ingot is physically separated from the silicon carbide residue. The total cutting time is 2.63 hours, and the cutting efficiency is increased by 50%.

[0078] Step 7: Turn off the power of the ultrasonic generator and the power of the cutting fluid supply system, turn off the power of the diamond wire running movement. Move the platform in the X direction under computer control to move the platform and the ingot away from the diamond wire. Remove the cut silicon carbide ingot and the silicon carbide corner residues separated by cutting, and measure the geometric dimensions and surface processing quality of the side surface and the reference plane of the silicon carbide. The diameter of the silicon carbide ingot is 150 mm, the thickness is 25 mm, the surface roughness of the side surface is 0.3 um, and the surface roughness of the reference plane is 0.3 um, meeting the quality standards.

[0079] Step 8: After the quality of the silicon carbide ingot is inspected and qualified, it is put into the next normal production process. The silicon carbide corner residues can be recycled and reused as synthetic moissanite to process synthetic moissanite ornaments.

[0080] Comparative Example 1

[0081] This comparative example uses the same diamond wire cutting method as in Example 1, but the difference is that the ultrasonic unit is moved to another place and directly applied to the roller in contact with the diamond wire to directly generate ultrasonic vibration on the diamond wire. The cutting fluid is still pumped to the surface of the diamond wire according to the original structure.

[0082] The remaining conditions such as ultrasonic frequency, power, wire running rate, etc. remain unchanged.

[0083] The ultrasonic wave directly acts on the roller in contact with the diamond, but the roller itself has a large self-weight and is usually tightly fixed on the mechanical main shaft. Therefore, it is difficult for the roller to perform a relatively large-amplitude high-frequency vibration under the action of the ultrasonic wave. Naturally, it is also difficult for the diamond wire on the roller to obtain a relatively large proportion of high-frequency vibration energy. So on the one hand, this vibration method has no vibration efficiency and extremely low energy utilization rate. On the other hand, since the diamond wire itself is vibrated, the roller fixing it will also be vibrated. Therefore, the geometric positioning of the diamond wire will be greatly affected. It is not only difficult to improve the cutting efficiency, but also easy to produce problems such as dimensional errors and wavy cutting surfaces, and it is not suitable for the cutting application of this hard ingot.

[0084] Comparative Example 2

[0085] This comparative example uses the same diamond wire cutting method as in Example 1, but the difference is that in an immersion method, the moving platform is inverted so that the ingot is immersed in a container filled with cutting fluid, and the diamond wire cuts below the liquid surface through multiple guide wheels. At the same time, two high-power ultrasonic generators with the same frequency as in Example 1 are placed in the cutting fluid.

[0086] As a result, on the one hand, the moving platform will be corroded by the immersed cutting fluid, seriously affecting the moving accuracy of the platform, or the platform will soon stop working properly. On the other hand, in the immersion ultrasonic application method, the ultrasonic energy is dispersed throughout the container and not concentrated at the cutting interface. Therefore, applying ultrasonic in this way hardly produces the effect of improving the cutting efficiency and the quality of the cut surface.

[0087] Comparative Example 3

[0088] This comparative example uses the same diamond wire cutting method as in Example 1, but the difference is that the distance between the liquid outlet and the ingot is adjusted to 1 cm. As a result, the ultrasonic energy decays rapidly in the air and is basically no different from when no ultrasonic is applied at all. The cutting rate is very slow and the quality of the cut surface is also poor.

[0089] Based on the above embodiments and comparative examples, it can be clearly seen that the processing equipment and the corresponding processing method provided by the embodiments of the present invention use the diamond wire cutting method to complete the processing of the side surface and the reference surface of the hard ingot. During the wire cutting process, the cutting fluid is pumped to form a flow beam, and the ultrasonic unit directly applies ultrasonic to the flow beam, significantly improving the focusing degree of the ultrasonic energy, assisting in completing the cutting process, and avoiding the processing errors and surface quality problems caused by directly applying ultrasonic to the diamond wire.

[0090] In addition, by adopting the technical solution provided by the embodiments of the present invention, the problems of pollution and waste of the hard material powder formed by grinding are also avoided, and the material utilization rate is significantly improved.

[0091] It should be understood that the above embodiments are only used to illustrate the technical concept and features of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. It cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A surface processing device for a crystal, comprising a loading module and a processing module. The loading module is used to load a hard ingot, and the processing module can move relative to the loading module for processing the hard ingot. It is characterized in that The processing module includes a wire saw unit, a cutting fluid pump unit, and an ultrasonic unit. The wire saw unit can drive the wire saw to move along the axial direction to process the hard ingot. The cutting fluid pump unit can continuously pump the cutting fluid onto the surface of the wire saw and make the cutting fluid flow in an attached manner on the surface of the wire saw to form a fluid beam. The ultrasonic unit is in contact with the cutting fluid and is used to directly apply ultrasonic waves to the fluid beam.

2. The surface processing equipment according to claim 1, wherein The wire saw moves along the gravity direction, and the liquid outlet channel of the cutting fluid pump unit and the ultrasonic unit are arranged above the cutting position of the wire saw. There are multiple groups of the liquid outlet channels and the ultrasonic unit, and they are rotationally symmetrically distributed with the wire saw as the axis.

3. The surface processing equipment according to claim 2, characterized in that, The cutting fluid pump unit includes a first liquid outlet channel and a second liquid outlet channel. The ultrasonic unit includes a first ultrasonic generator and a second ultrasonic generator. The first ultrasonic generator is arranged in cooperation with the first liquid outlet channel, and the second ultrasonic generator is arranged in cooperation with the second liquid outlet channel. The first liquid outlet channel and the second liquid outlet channel are oppositely arranged with the wire saw as the axis, and the liquid outlet directions both point to the wire saw.

4. The surface processing device according to claim 2 or 3, characterized in that The distance between the outlet of the liquid outlet channel and the hard ingot is 3 - 5 mm.

5. The surface processing equipment according to claim 2, characterized in that, The cutting fluid pump unit further includes a cutting fluid recycler, which is arranged below the wire saw and is used to collect the cutting fluid in the fluid beam and pump the collected cutting fluid to the liquid outlet channel.

6. The surface processing device according to claim 1, wherein Diamond particles are embedded on the surface of the wire saw, and the particle size of the diamond particles is 3 - 12 μm. The diameter change rate of the wire saw is below 2%.

7. The surface processing device according to claim 6, characterized in that, The diameter of the wire saw is 0.45 - 0.90 mm.

8. The surface processing equipment according to claim 1, characterized in that, The loading module includes a precision moving platform with at least two degrees of freedom. The precision moving platform includes a fixed part and a moving part. The hard ingot can be fixed on the moving part, and at least two of the degrees of freedom are vertically cross - arranged with the geometric axis of the hard ingot. Moreover, the geometric axis of the ingot is parallel to the wire saw at the cutting position.

9. The surface processing equipment according to claim 8, wherein The precision moving platform includes a first track and a second track. The first track is fixedly arranged, and the second track is vertically cross - arranged with the first track and is slidably matched with the first track and can be driven to translate along the extension direction of the first track. The hard ingot is fixedly arranged on the second track and can be driven to translate along the extension direction of the second track.

10. The surface processing equipment according to claim 1, characterized in that, The wire saw is a closed - loop ring. Or the wire saw is a non - closed - loop linear type, and the wire saw unit can drive the wire saw to perform a linear reciprocating motion.

Images