Method for rapidly cutting silicon carbide crystal bar

Abstract

The invention relates to the technical field of silicon carbide crystal bar processing, in particular to a method for rapidly cutting a silicon carbide crystal bar, which comprises the following steps of: accurately fixing the crystal bar through a fixing mechanism, performing efficient cutting by matching a fixed abrasive cutting line with multifunctional cooling and lubricating mortar, and optimizing cutting parameters and new line supply quantity through a dynamic control system. The fixed abrasive cutting line is composed of superfine tungsten filaments and nanoscale diamond particles, and mortar provides cooling, lubricating and auxiliary cutting effects. According to the method, the cutting efficiency is remarkably improved, the material loss is reduced, the wafer surface quality consistency is guaranteed, the yield is increased to 98% or above, and an efficient and economical solution is provided for SiC material processing.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor material processing, and in particular relates to a method for rapidly cutting a silicon carbide crystal rod. Background Art

[0002] In the semiconductor material field, silicon carbide (SiC) has attracted considerable attention due to its excellent physical and chemical properties. SiC single crystals, characterized by a wide bandgap, high thermal conductivity, high electron saturation mobility, and a high breakdown electric field, are widely used in the manufacture of high-performance electronic devices. However, the processing of SiC single crystals, particularly in the application of multi-wire sawing (MWS) technology, still faces numerous challenges. Traditional MWS methods rely primarily on free abrasives carried by the cutting wires to cut SiC ingots. This approach lacks precise control over the movement and distribution of the abrasive during the cutting process, resulting in variability in the specifications of the SiC wafers produced from each cut and difficulty ensuring batch-to-batch consistency. Furthermore, traditional slurry sawing is inefficient, requiring significant time to complete a single cut of large or thick SiC ingots, significantly increasing the cutting cycle and reducing overall production efficiency. Furthermore, the relatively large diameter of traditional MWS wires results in significant kerf loss during the cutting process, wasting a significant amount of expensive SiC material and further increasing production costs. These challenges negatively impact the rapid crystal quality iteration and market competitiveness of SiC single crystal substrates.

[0003] In the prior art, a method for segmented cutting of silicon carbide crystals using a multi-wire saw with publication number CN101979230B changes the cutting speed according to the cutting length corresponding to different positions of the crystal column cross section, thereby changing the uniform feed cutting of the workbench to continuous, segmented feeding at different speeds, thereby improving cutting efficiency and reducing cutting costs. However, this technical solution still relies on the traditional mortar cutting method, and the distribution and motion control of the abrasive in the mortar have certain limitations, which may cause fluctuations in the surface quality of the wafer during the cutting process. In addition, due to the coarse cutting wire diameter, the kerf loss generated during the cutting process is large, the material utilization rate is low, and there is still room for improvement in cutting efficiency.

[0004] Another existing technology, a multi-wire cutting method for silicon carbide wafers with publication number CN115958709B, avoids the errors generated when multiple silicon carbide crystal rods are bonded together, reduces the gaps in the crystal rod splicing and the relaxation phenomenon of the tension transmitted in the wire mesh during the reciprocating cutting of the steel wire, thereby improving the surface shape of the wafer after cutting and increasing the utilization rate of the roller to reduce manufacturing costs. However, this technical solution still needs to rely on the traditional steel wire cutting method, and the cutting efficiency is affected by the speed and wear of the steel wire. At the same time, the surface quality of the wafer may fluctuate due to uneven tension during the steel wire cutting process, and the problem of material loss caused by the thick cutting wire diameter has not been solved. In addition, this method has high requirements on the accuracy of the equipment, which may increase the cost of equipment investment.

[0005] In summary, existing methods for cutting silicon carbide ingots still have room for improvement in terms of cutting efficiency, material utilization, wafer surface quality consistency, and production costs. In particular, in practical applications, improving cutting efficiency, reducing material loss, ensuring wafer surface quality consistency, and reducing processing costs are technical challenges that urgently need to be addressed. Therefore, the present invention aims to provide a method for rapidly cutting silicon carbide ingots through innovative process design and technological improvements, thereby overcoming the shortcomings of existing technologies and providing a more efficient and economical solution for SiC material processing. Summary of the Invention

[0006] The present invention addresses the problems of low efficiency, low material utilization, and poor surface quality consistency in the existing technology during the cutting process of silicon carbide crystal rods, and provides a method for quickly cutting silicon carbide crystal rods. The specific technical solution is as follows: A method for rapidly cutting a silicon carbide ingot is characterized by comprising the following steps: first, precisely fixing the silicon carbide ingot via a fixing mechanism to ensure stability during the cutting process; second, using a fixed abrasive cutting wire to complete the cutting task, wherein the fixed abrasive cutting wire is composed of an ultrafine tungsten wire matrix and nano-scale diamond particles uniformly distributed on the surface, wherein the tungsten wire matrix has a diameter ranging from 0.06 mm to 0.10 mm, and the diamond particles have a particle size ranging from 3 μm to 8 μm; simultaneously, introducing a multifunctional cooling and lubricating mortar as an auxiliary medium, wherein the mortar is supplied via a mortar supply system, and the flow rate is set to 80 L / min to 120 L / min; accurately setting the cutting table speed, swing angle, and swing speed via a cutting parameter dynamic control system, wherein the cutting table speed is set to 2.5 mm / h to 4.0 mm / h, the swing angle is set to 2° to 4°, and the swing speed is 250° / min to 350° / min in the stable stage; finally, dynamically adjusting the new wire supply amount according to the cutting depth via a new wire supply calculation module.

[0007] Preferably, the fixing mechanism includes a high-precision resin fixture, a cutting plate and a vacuum adsorption component. The silicon carbide crystal rod is bonded to the resin fixture by high-strength UV glue, and the resin fixture is fixedly connected to the cutting plate by UV glue. The three form an integral structure; the vacuum adsorption component includes a metal suction cup and a vacuum generator. The adsorption surface of the metal suction cup is fitted with the bottom of the cutting plate. The vacuum generator is connected to the metal suction cup through a pipe to form a negative pressure environment inside the metal suction cup. The vacuum value of the metal suction cup is set between -70KPa and -90KPa.

[0008] Preferably, an annular groove is provided at the bottom of the metal suction cup, and a plurality of evenly distributed micropores are provided on the inner wall of the annular groove. The micropores are connected to the adsorption surface, and the surface of the adsorption surface is provided with radial grooves to enhance the adsorption effect; the flatness of the end face of the silicon carbide crystal rod needs to be controlled within 20μm, and the deviation in the X direction and the Y direction after crystal orientation calibration shall not exceed 2′.

[0009] Preferably, the fixed abrasive cutting wire is wound on a high-speed drive roller, and the roller is driven by a servo motor to achieve high-speed reciprocating motion; the cutting wire web tension value is set in the range of 30N to 40N, and the cutting wire web speed is set to 1000m / min to 2000m / min, preferably 1200m / min; the cutting wire is adjusted in real time by a tension adjustment device during the cutting process, and the tension adjustment device includes multiple sets of pulleys and elastic compensation components installed on the cutting wire path, and the pulley realizes automatic compensation of tension through the deformation of the elastic compensation component.

[0010] Preferably, the multifunctional cooling and lubricating mortar supply system includes a mortar storage tank, a delivery pipeline and an intelligent flow control valve. The mortar storage tank is filled with a composite mortar with a free abrasive particle size D50 of 3 μm; the inner wall of the delivery pipeline is provided with a spiral guide groove to improve the fluidity and uniformity of the mortar; the bottom of the mortar storage tank is provided with a high-efficiency stirring device, which includes a rotating shaft and multiple groups of inclined stirring blades fixed on the rotating shaft. The stirring blades are spirally arranged to enhance the mixing effect of the mortar.

[0011] Preferably, the cutting parameter dynamic control system includes a cutting table speed adjustment module, a swing angle adjustment module and a swing speed adjustment module; the cutting table speed adjustment module is driven by a stepper motor, the output shaft of the stepper motor is connected to the transmission mechanism of the cutting table, the transmission mechanism includes a gear set and a rack, the gear set is engaged with the rack to achieve smooth movement of the cutting table; the swing angle adjustment module is driven by a servo motor, the output shaft of the servo motor is connected to the swing mechanism, the swing mechanism includes a crank and a connecting rod, the crank and the connecting rod are hinged to achieve reciprocating swinging motion of the workbench.

[0012] Preferably, the new line supply calculation module includes a data acquisition unit, a calculation unit and a new line supply device. The data acquisition unit monitors the cutting depth in real time through a high-precision displacement sensor and transmits the data to the calculation unit. The calculation unit calculates the cutting depth according to the formula Dynamically adjust the new wire supply amount, where r represents the cutting radius, with a fixed value of 75.125, C represents the cutting depth, k is the correction coefficient, with a value range of 0.15 to 0.20, and b is a constant with a value of 10; the new wire supply device includes a wire storage disk and a wire feeding mechanism. The wire feeding mechanism is driven by a stepper motor, and the output shaft of the stepper motor is connected to the wire storage disk to achieve precise supply of new wire.

[0013] Preferably, the method is suitable for silicon carbide crystal rods with a diameter of 80 mm and a length of 250 mm; during the cutting process, the cutting table speed is set to 3.0 mm / H, the cutting wire mesh speed is 1500 m / min, the mortar flow rate is 100 L / min, the workbench swing angle is set to 3°, and the swing speed is 300° / min in the stable stage.

[0014] Preferably, the nano-scale diamond particles on the fixed abrasive cutting wire provide the main cutting force, directly acting on the surface of the silicon carbide crystal rod for grinding; the free abrasive in the multifunctional cooling and lubricating slurry plays an auxiliary role in the cutting gap, and the two cooperate with each other to improve the cutting ability; during the cutting process, the cutting wire cuts the crystal rod through high-speed reciprocating motion, and the slurry carries away the debris generated by the cutting during the flow process and plays a role of cooling and lubrication.

[0015] Compared with the existing technology, the beneficial effects of the present invention are: through the synergistic effect of innovative cutting wire design, the application of multifunctional mortar and dynamic parameter control system, the present invention can significantly improve the cutting efficiency of silicon carbide crystal rods, reduce material loss, and ensure the consistency of wafer surface quality; in actual application, the present invention can increase the yield to more than 98%, significantly reduce processing costs, and provide a more efficient and economical solution for SiC material processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the silicon carbide crystal rod fixing mechanism in the present invention; Figure 2 This is the front view of the metal suction cup; Figure 3 This is the back view of the metal suction cup; Figure 4 Schematic diagram of the structure of the fixed abrasive cutting wire; Figure 5 This is a structural diagram of a multifunctional cooling and lubricating mortar supply system; Figure 6 This is a schematic diagram of the module composition of the cutting parameter dynamic control system; Figure 7 Schematic diagram of the working principle of the calculation module for the new line supply.

[0017] In the figure: 1 resin fixture, 2 cutting plate, 3 vacuum adsorption component, 4 ultrafine tungsten wire matrix, 5 diamond particles, 6 roller, 7 servo motor, 8 pulley, 9 elastic compensation component, 10 mortar storage tank, 11 delivery pipeline, 12 intelligent flow control valve, 13 spiral guide groove, 14 stirring device, 15 rotating shaft, 16 stirring blade, 31 metal suction cup, 32 vacuum generator, 33 pipeline, 34 annular groove, 35 micropore, 36 radial groove. DETAILED DESCRIPTION

[0018] The present invention provides a method for rapidly cutting silicon carbide crystal rods. Figure 1 To the attached Figure 7 The specific implementation method is described in detail. In practical application, this method achieves efficient and high-quality silicon carbide ingot cutting through the synergistic effect of the fixing mechanism, the fixed abrasive cutting wire, the multifunctional cooling and lubricating slurry supply system, the cutting parameter dynamic control system, and the new wire supply calculation module.

[0019] First of all, the fixation of silicon carbide crystal rod is the basis of the entire cutting process, and its stability directly affects the cutting efficiency and surface quality. Figure 1-3 As shown, the fixing mechanism includes a high-precision resin fixture 1, a cutting plate 2, and a vacuum adsorption assembly 3. The SiC ingot is bonded to the resin fixture 1 with high-strength UV adhesive, which is then fixed to the cutting plate 2 with UV adhesive, forming a single integrated structure. The vacuum adsorption assembly 3 consists of a metal suction cup 31 and a vacuum generator 32. The suction surface of the metal suction cup 31 is in contact with the bottom of the cutting plate 2. The vacuum generator 32 is connected to the metal suction cup 31 via a pipe 33, creating a negative pressure environment within the metal suction cup 31. The vacuum value is set between -70 kPa and -90 kPa. The bottom of the metal suction cup 31 has an annular groove 34, and the inner wall is provided with multiple evenly distributed micropores 35, which are connected to the adsorption surface. The surface of the adsorption surface is provided with radial grooves 36 to enhance the adsorption effect. The flatness of the SiC ingot end face must be controlled within 20 μm. After crystal orientation calibration, the re-inspection deviation does not exceed 2′ in the X direction and 2′ in the Y direction. The design of the fixing mechanism can effectively reduce vibration and displacement during the cutting process, thereby ensuring cutting accuracy.

[0020] Secondly, the bonded abrasive cutting wire is the core component to achieve efficient cutting. Figure 4As shown, the fixed abrasive cutting wire consists of an ultrafine tungsten wire matrix 4 and nano-scale diamond particles 5 evenly distributed on the surface. The diameter of the tungsten wire matrix 4 ranges from 0.06 mm to 0.10 mm, and the particle size of the diamond particles 5 ranges from 3 μm to 8 μm. The fixed abrasive cutting wire is wound on a high-speed drive roller 6, which is driven by a servo motor 7 to achieve high-speed reciprocating motion. The cutting wire web tension value is set within the range of 30 N to 40 N, and the cutting wire web speed is set between 1000 m / min and 2000 m / min, preferably 1200 m / min. The cutting wire is adjusted in real time during the cutting process by a tension adjustment device. The tension adjustment device includes multiple sets of pulleys 8 and elastic compensation components 9 installed on the cutting wire path. The pulleys 8 automatically compensate for tension through the deformation of the elastic compensation components 9. The nano-scale diamond particles 5 on the fixed abrasive cutting wire directly act on the surface of the silicon carbide crystal rod for efficient grinding, providing the main cutting force.

[0021] At the same time, the multifunctional cooling and lubricating mortar is used as an auxiliary medium to cool, lubricate and remove chips during the cutting process. Figure 5 As shown, the multifunctional cooling and lubricating slurry supply system includes a mortar storage tank 10, a delivery pipeline 11, and an intelligent flow control valve 12. The mortar storage tank 10 contains a composite mortar with a free abrasive particle size D50 of 3 μm. The inner wall of the delivery pipeline 11 is provided with a spiral guide groove 13 to improve the fluidity and uniformity of the mortar. A high-efficiency stirring device 14 is installed at the bottom of the mortar storage tank 10. The stirring device 14 includes a rotating shaft 15 and multiple sets of inclined stirring blades 16 fixed to the rotating shaft 15. The stirring blades 16 are arranged in a spiral shape to enhance the mixing effect of the mortar. The slurry is supplied through the mortar supply system, with a flow rate set at 80 L / min to 120 L / min. The free abrasive in the multifunctional cooling and lubricating slurry assists cutting in the cutting gap, working together with the fixed abrasive cutting line to enhance cutting performance. Simultaneously, the slurry removes cutting debris during flow and provides cooling and lubrication, significantly improving cutting efficiency and the consistency of wafer surface quality.

[0022] The dynamic control system of cutting parameters can further optimize the cutting process by accurately setting the cutting table speed, swing angle and swing speed. Figure 6As shown, the cutting parameter dynamic control system includes a cutting table speed adjustment module, a swing angle adjustment module and a swing speed adjustment module. The cutting table speed adjustment module is driven by a stepper motor, and the output shaft of the stepper motor is connected to the transmission mechanism of the cutting table. The transmission mechanism includes a gear set and a rack, and the gear set is engaged with the rack to achieve smooth movement of the cutting table. The swing angle adjustment module is driven by a servo motor, and the output shaft of the servo motor is connected to the swing mechanism. The swing mechanism includes a crank and a connecting rod, and the crank and the connecting rod are hinged to achieve reciprocating swinging motion of the workbench. The cutting table speed is set to 2.5mm / H to 4.0mm / H, the swing angle is set to 2° to 4°, and the swing speed is 250° / min to 350° / min in the stable stage. Through the above dynamic control system, the parameters can be flexibly adjusted according to actual cutting needs to ensure the efficiency and stability of the cutting process.

[0023] Finally, the new wire supply calculation module dynamically adjusts the new wire supply amount according to the cutting depth to ensure the reasonable use of wire during the cutting process. Figure 7 As shown, the new wire supply calculation module includes a data acquisition unit, a calculation unit and a new wire supply device. The data acquisition unit monitors the cutting depth in real time through a high-precision displacement sensor and transmits the data to the calculation unit. The calculation unit calculates the new wire supply device according to the formula Dynamically adjust the new wire supply, where r represents the cutting radius, fixed at 75.125, C represents the cut depth, k is a correction factor ranging from 0.15 to 0.20, and b is a constant, set to 10. The new wire supply device consists of a wire storage reel and a wire feed mechanism. The feed mechanism is driven by a stepper motor, whose output shaft is connected to the reel to ensure precise new wire supply. This formula and modular design allows for real-time adjustment of the new wire supply based on the actual cutting depth, avoiding wire waste or shortage.

[0024] In practical applications, the present invention is applicable to silicon carbide crystal rods with a diameter of 80 mm and a length of 250 mm. During the cutting process, the cutting table speed is set to 3.0 mm / H, the cutting wire mesh speed is 1500 m / min, the slurry flow rate is 100 L / min, the workbench swing angle is set to 3°, and the swing speed is 300° / min in the stable stage. Through the optimized combination of the above parameters, the cutting efficiency can be significantly improved, the material loss can be reduced, and the consistency of the wafer surface quality can be ensured. Experimental results show that the present invention can increase the yield to more than 98% in practical applications, significantly reduce processing costs, and provide a more efficient and economical solution for SiC material processing.

[0025] In summary, the present invention solves the problems of low efficiency, low material utilization and poor surface quality consistency in the existing technology during the silicon carbide ingot cutting process through the synergistic effect of innovative cutting wire design, application of multifunctional mortar and dynamic parameter control system. Figure 1 To the attached Figure 7 The specific implementation methods further verify that the technical solution of the present invention has high practicality and promotion value.

[0026] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for rapidly cutting silicon carbide ingots, characterized in that The following steps are involved: The silicon carbide crystal rod is fixed by a fixing mechanism; the cutting task is completed by a fixed abrasive cutting wire, which is composed of an ultrafine tungsten wire matrix and nano-scale diamond particles evenly distributed on the surface. The diameter of the tungsten wire matrix ranges from 0.06mm to 0.10mm, and the particle size of the diamond particles ranges from 3μm to 8μm; a multifunctional cooling and lubricating mortar is introduced as an auxiliary medium, and the mortar is supplied through a mortar supply system, and the flow rate is set to 80L / min to 120L / min; the cutting table speed, swing angle and swing speed are set through the cutting parameter dynamic control system, the cutting table speed is set to 2.5mm / H to 4.0mm / H, the swing angle is set to 2° to 4°, and the swing speed is 250° / min to 350° / min in the stable stage; the new wire supply amount is dynamically adjusted according to the cutting depth through the new wire supply calculation module.

2. The method for rapidly cutting a silicon carbide ingot according to claim 1, wherein: The fixing mechanism includes a high-precision resin fixture (1), a cutting plate (2) and a vacuum adsorption component (3). The silicon carbide crystal rod is bonded to the resin fixture (1) by high-strength UV glue, and the resin fixture (1) is fixedly connected to the cutting plate (2) by UV glue, and the three form an integral structure; the vacuum adsorption component (3) includes a metal suction cup (31) and a vacuum generator (32). The adsorption surface of the metal suction cup (31) is in contact with the bottom of the cutting plate (2), and the vacuum generator (32) is connected to the metal suction cup (31) through a pipe (33), so that a negative pressure environment is formed inside the metal suction cup (31), and the vacuum value is set to -70KPa to -90KPa.

3. The method for rapidly cutting a silicon carbide ingot according to claim 2, wherein: An annular groove (34) is provided at the bottom of the metal suction cup (31), and a plurality of evenly distributed micropores (35) are provided on the inner wall of the annular groove (34), the micropores (35) are connected to the adsorption surface, and radial grooves (36) are provided on the surface of the adsorption surface to enhance the adsorption effect; the flatness of the end face of the silicon carbide crystal rod is controlled within 20 μm, and the re-inspection deviation after crystal orientation calibration does not exceed 2′ in the X direction and does not exceed 2′ in the Y direction.

4. The method for rapidly cutting a silicon carbide ingot according to claim 1, wherein: The fixed abrasive cutting wire is wound on a high-speed driving roller (6), and the roller (6) is driven by a servo motor (7) to realize high-speed reciprocating motion; the tension value of the cutting wire net is set within the range of 30N to 40N, and the cutting wire net speed is set within the range of 1000m / min to 2000m / min; the cutting wire is adjusted in real time by a tension adjustment device during the cutting process, and the tension adjustment device includes a plurality of pulleys (8) and an elastic compensation component (9) installed on the cutting wire path, and the pulley (8) realizes automatic compensation of tension through deformation of the elastic compensation component (9).

5. The method for rapidly cutting a silicon carbide ingot according to claim 1, wherein: The multifunctional cooling and lubricating mortar supply system comprises a mortar storage tank (10), a delivery pipe (11) and an intelligent flow control valve (12). The mortar storage tank (10) is filled with a composite mortar with a free abrasive particle size D50 of 3 μm. A spiral guide groove (13) is provided on the inner wall of the delivery pipe (11) to improve the fluidity and uniformity of the mortar. A high-efficiency stirring device (14) is provided at the bottom of the mortar storage tank (10). The stirring device (14) comprises a rotating shaft (15) and a plurality of groups of inclined stirring blades (16) fixed on the rotating shaft (15). The stirring blades (16) are arranged in a spiral shape to enhance the mixing effect of the mortar.

6. The method for rapidly cutting a silicon carbide ingot according to claim 1, wherein: The cutting parameter dynamic control system includes a cutting table speed adjustment module, a swing angle adjustment module and a swing speed adjustment module; the cutting table speed adjustment module is driven by a stepper motor, the output shaft of the stepper motor is connected to the transmission mechanism of the cutting table, the transmission mechanism includes a gear set and a rack, the gear set and the rack are engaged to achieve smooth movement of the cutting table; the swing angle adjustment module is driven by a servo motor, the output shaft of the servo motor is connected to the swing mechanism, the swing mechanism includes a crank and a connecting rod, the crank and the connecting rod are articulated to achieve reciprocating swinging motion of the workbench.

7. The method for rapidly cutting a silicon carbide ingot according to claim 1, wherein: The new wire supply calculation module includes a data acquisition unit, a calculation unit and a new wire supply device. The data acquisition unit monitors the cutting depth in real time through a high-precision displacement sensor and transmits the data to the calculation unit; The calculation unit is based on the formula Dynamically adjust the new wire supply amount, where r represents the cutting radius, with a fixed value of 75.125, C represents the cutting depth, k is the correction coefficient, with a value range of 0.15 to 0.20, and b is a constant with a value of 10; the new wire supply device includes a wire storage disk and a wire feeding mechanism. The wire feeding mechanism is driven by a stepper motor, and the output shaft of the stepper motor is connected to the wire storage disk to achieve precise supply of new wire.

8. The method for rapidly cutting a silicon carbide ingot according to claim 1, wherein: This method is suitable for silicon carbide crystal rods with a diameter of 80 mm and a length of 250 mm. During the cutting process, the cutting table speed is set to 3.0 mm / h, the cutting wire mesh speed is 1500 m / min, the mortar flow rate is 100 L / min, the worktable swing angle is set to 3°, and the swing speed is 300° / min in the stable stage.

9. The method for rapidly cutting a silicon carbide ingot according to claim 1, wherein: The nano-scale diamond particles on the fixed abrasive cutting wire provide the main cutting force, directly acting on the surface of the silicon carbide crystal rod for grinding; The free abrasive in the multifunctional cooling and lubricating slurry plays an auxiliary role in the cutting gap, and the two work together to improve the cutting ability. During the cutting process, the cutting wire cuts the crystal rod through high-speed reciprocating motion. During the flow of the slurry, it carries away the debris generated by the cutting and plays a cooling and lubricating role.

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