Nested protection device and method in crystal ingot cutting process

Abstract

The invention discloses a nesting protection device and method in a crystal ingot cutting process, the nesting protection device comprises an inner elastic buffer layer, a middle stress dispersion layer and an outer rigid supporting layer, the inner elastic buffer layer is made of a high-molecular polymer material, the thickness of the inner elastic buffer layer is 0.5-2mm, the middle stress dispersion layer is composed of honeycomb-shaped metal grids, and the outer rigid supporting layer is made of a high-molecular polymer material. The unit size is 1-3mm, the outer rigid supporting layer is made of a high-strength carbon fiber composite material, and the thickness of the outer rigid supporting layer is 3mm-5mm. After cutting is completed, nondestructive testing is conducted on the crystal ingot, and it is ensured that the interior and the surface of the crystal ingot are free of hidden defects. According to the whole nested protection method, efficient and high-quality crystal ingot cutting results are achieved by accurately controlling nested structure parameters, a stress distribution optimization algorithm and a heat effect management model, and the requirements of the third-generation semiconductor industry for high-quality silicon carbide wafers are met. Core equipment of the method comprises a nested protection device, a stress monitoring system, a heat effect control system and other modules, and all the modules work cooperatively to complete the crystal ingot cutting task.

Description

Technical Field

[0001] The present invention relates to a nested protection method during the ingot cutting process. Background Art

[0002] With the wide application of silicon carbide (SiC) materials in the fields of high-power and high-temperature semiconductor devices, the ingot cutting process has become a key technical link in its manufacturing process. However, due to the extremely high hardness (Mohs hardness of 9.2 - 9.5) and easy brittleness of silicon carbide, traditional cutting methods are prone to defects such as chipping and cracking, seriously affecting the qualification rate and production efficiency of wafers. Therefore, it is of great significance to develop a nested protection method that can effectively protect the ingot from damage during the cutting process.

[0003] A low-loss silicon carbide wafer slicing method with the publication number CN115338546B, and the publication date is January 7, 2025. This patent uses laser stealth cutting technology to form cracks on the silicon carbide crystal column, thereby separating a silicon carbide thin sheet with a thickness of 80 - 200 μm and a silicon carbide thick sheet with a thickness of 625 - 3920 μm. This technology significantly reduces the material loss during the cutting process and improves the cutting efficiency. However, this solution mainly focuses on the improvement of the cutting method and does not elaborate on the overall protection measures for the ingot during the cutting process. Especially during the cutting process, uneven stress distribution at the edge and inside of the ingot may lead to the propagation of microcracks, thereby affecting the quality and qualification rate of the wafers.

[0004] A silicon carbide product positioning cutting and processing device with the publication number CN118595640B, and the publication date is October 18, 2024. This patent uses a clamping mechanism to clamp the silicon carbide graphite plate in all directions and uses a spring pressing plate to complete the precise clamping on both sides of the cutting area, thereby improving the stability and precision during the cutting process. However, the clamping mechanism of this technical solution is mainly designed for planar silicon carbide products and has limited applicability to cylindrical or irregularly shaped ingots. In addition, this solution does not consider the overall stress distribution and thermal effect problems of the ingot during the cutting process, which may cause hidden defects inside the ingot after cutting and affect the subsequent processing performance.

[0005] The above problems indicate that the existing silicon carbide ingot cutting technologies have made significant progress in cutting efficiency and material loss reduction, but there are still deficiencies in the overall protection of the ingot during the cutting process, stress distribution control, and the quality stability of the wafers after cutting. Therefore, the present invention provides a nested protection method during the ingot cutting process, aiming to improve the qualification rate and production efficiency of wafers by optimizing the nested structure design, improving the uniformity of stress distribution, reducing the thermal effect and mechanical damage during the cutting process, so as to meet the requirements of the third-generation semiconductor industry for high-quality silicon carbide wafers. Summary of the Invention

[0006] The object of the present invention is to provide a nested protection device and method during the ingot cutting process to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: A nested protection device during the ingot cutting process, including an inner elastic buffer layer, an intermediate stress dispersion layer, and an outer rigid support layer. The inner elastic buffer layer is made of a polymer material with a thickness of 0.5 mm to 2 mm. The intermediate stress dispersion layer is composed of a honeycomb metal grid with a cell size of 1 mm to 3 mm. The outer rigid support layer is made of a high-strength carbon fiber composite material with a thickness of 3 mm to 5 mm.

[0008] Preferably, the gap range between the inner elastic buffer layer and the ingot to be cut is 0.1 mm to 0.3 mm.

[0009] Preferably, the cell shape of the honeycomb metal grid is a regular hexagon.

[0010] Preferably, a nested protection method during the ingot cutting process includes the following steps: Place the ingot to be cut in the nested protection device described in any one of claims 1 to 3, and adjust the gap between the inner elastic buffer layer and the ingot to 0.1 mm to 0.3 mm. Calculate the effective stress value inside the ingot through a stress optimization algorithm based on finite element analysis and adjust the nested structure parameters. At the same time, use the thermal effect management model to dynamically adjust the cutting speed and coolant flow rate to reduce the influence of thermal effects on the ingot.

[0011] Preferably, the calculation formula for the effective stress value is:

[0012]

[0013] where, σ eff represents the effective stress value, σ x , σ y , σ z are the principal stresses in three directions respectively, and V is the volume of the ingot.

[0014] Preferably, the calculation formula for the thermal effect management model is:

[0015]

[0016] where, T max is the maximum temperature on the ingot surface, T0 is the initial temperature, Q is the heat input power per unit time, t is the cutting time, k is the thermal conductivity, and A is the heat conduction area.

[0017] Preferably, after cutting is completed, the ingot is subjected to non-destructive testing, and the testing methods include ultrasonic testing or X-ray testing.

[0018] Preferably, it includes a nested protection device, a stress monitoring system, and a thermal effect control system. The nested protection device is the multi-layer nested structure described in any one of claims 1 to 3. The stress monitoring system is used to collect the stress distribution data inside the ingot in real time, and the thermal effect control system is used to dynamically adjust the cutting speed and coolant flow rate according to the thermal effect management model.

[0019] Preferably, the thickness of the inner elastic buffer layer of the nested protection device is 1 mm, the unit size of the intermediate stress dispersion layer is 2 mm, and the thickness of the outer rigid support layer is 4 mm.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: After cutting with the present invention, non-destructive testing is carried out on the ingot to ensure that there are no hidden defects inside and on the surface. The entire nested protection method realizes efficient and high-quality ingot cutting results by precisely controlling the nested structure parameters, the stress distribution optimization algorithm, and the thermal effect management model, and is suitable for the demand of the third-generation semiconductor industry for high-quality silicon carbide wafers. The core equipment of this method includes modules such as a nested protection device, a stress monitoring system, and a thermal effect control system, and each module works together to complete the ingot cutting task. Description of the Drawings

[0021] Figure 1 : Schematic diagram of the structure of the nested protection device, showing the multi-layer nested design of the inner elastic buffer layer, the intermediate stress dispersion layer, and the outer rigid support layer.

[0022] Figure 2 : Schematic diagram of the nested state of the ingot in the nested protection device, marking the gap range between the ingot and the inner elastic buffer layer as 0.1 - 0.3 mm.

[0023] Figure 3 : Flow chart of the stress distribution optimization algorithm based on finite element analysis, showing the process of calculating the effective stress value and its adjustment method for the nested structure parameters.

[0024] Figure 4 : Control flow chart of the thermal effect management model, including the dynamic adjustment process of the cutting speed and coolant flow rate to reduce the impact of thermal effects on the ingot.

[0025] In the figure, 1 is the inner layer, 2 is divided into three layers, 3 is the outer layer, and 4 is the ingot. Detailed Embodiments

[0026] The present invention relates to a nested protection method during the ingot cutting process. The core lies in designing and fabricating a protection device with a multi-layer nested structure, and realizing precise control of the ingot cutting process through a stress optimization algorithm and a thermal effect management model. The following is combined with the attached Figure 1 to the attached Figure 4And specific embodiments are used to elaborate in detail the specific implementation manners of the present invention.

[0027] First, the design and preparation of the nested protection device are one of the key steps of the present invention. As shown in the appendix Figure 1 The device consists of an inner elastic buffer layer, a middle stress dispersion layer, and an outer rigid support layer. The inner elastic buffer layer is made of a polymer material, and its thickness ranges from 0.5 to 2 mm, preferably 1 mm. This material has good elasticity and toughness, and can absorb the local impact force generated during the cutting process, thereby effectively reducing the risk of damage to the surface of the ingot. The middle stress dispersion layer is composed of a honeycomb metal grid, and its unit size ranges from 1 to 3 mm, preferably 2 mm. The design of the honeycomb structure can evenly distribute the stress concentration during cutting, avoiding the generation of microcracks inside the ingot due to excessive local stress. The outer rigid support layer is made of a high-strength carbon fiber composite material, and its thickness ranges from 3 to 5 mm, preferably 4 mm. This material not only has excellent mechanical strength but also can ensure the stability of the entire nested protection device during the cutting process. The layers are fixed by adhesives or mechanical connection methods to ensure the tightness and reliability of the overall structure.

[0028] When placing the ingot to be cut in the nested protection device, it is necessary to adjust the gap between the inner elastic buffer layer and the ingot to 0.1 - 0.3 mm, preferably 0.2 mm. This gap range is set based on experimental data and theoretical analysis, aiming to keep the ingot in a stable nested state during the cutting process. As shown in the appendix Figure 2 The gap between the ingot and the inner elastic buffer layer is adjusted by a precision measuring tool to ensure that it meets the design requirements. In addition, the geometric dimensions of the nested protection device should be customized according to the actual shape and size of the ingot to further improve the protection effect.

[0029] To optimize the performance of the nested protection device, the present invention introduces a stress optimization algorithm based on finite element analysis. As shown in the appendix Figure 3 The core formula of this algorithm is as follows:

[0030]

[0031] Where, σ eff represents the effective stress value, σ x , σ y , σ zare the principal stresses in three directions respectively, and V is the volume of the ingot. The stress distribution inside the ingot during the cutting process is calculated by this formula, and the parameters of the nested structure are adjusted accordingly. For example, when the calculation result shows that the effective stress value in a certain area is too high, the stress concentration in this area can be reduced by increasing the thickness of the inner elastic buffer layer or adjusting the element size of the intermediate stress dispersion layer. The implementation process of this algorithm includes the following steps: First, a three-dimensional model of the ingot and its nested protection device is established using finite element analysis software; Second, the cutting load is applied to the model and the cutting process is simulated; Then, the stress distribution data inside the ingot is extracted and substituted into the above formula for calculation; Finally, the parameters of the nested structure are optimized and adjusted according to the calculation results until the stress distribution reaches a uniform state.

[0032] During the cutting process, the influence of thermal effects on the ingot is a factor that cannot be ignored. For this reason, the present invention introduces a thermal effect management model, and its core formula is as follows:

[0033] The calculation formula of the thermal effect management model is:

[0034]

[0035] where, T max is the maximum temperature on the surface of the ingot, T0 is the initial temperature, Q is the heat input power per unit time, t is the cutting time, k is the thermal conductivity, and A is the heat conduction area. Through this model, the cutting speed and the coolant flow rate can be dynamically adjusted, thereby reducing the influence of thermal effects on the quality of the ingot. As shown in the appendix Figure 4 The implementation process of the thermal effect management model includes the following steps: First, determine the heat input power Q per unit time according to the parameters of the cutting equipment; Second, monitor the cutting time and the surface temperature of the ingot in real time and record the relevant data; Then, substitute these data into the above formula to calculate the maximum temperature T max on the surface of the ingot; Finally, adjust the cutting speed and the coolant flow rate according to the calculation results. For example, when the calculation result shows that the surface temperature of the ingot is too high, the temperature can be effectively reduced by reducing the cutting speed or increasing the coolant flow rate.

[0036] After cutting is completed, the ingot needs to be subjected to non-destructive testing to ensure that there are no hidden defects inside and on the surface. The methods of non-destructive testing include ultrasonic testing, X-ray testing, etc., and appropriate testing means can be selected according to actual needs. During the testing process, if defects are found in the ingot, the parameters of the nested protection device need to be further optimized and adjusted until the cutting result meets the quality requirements.

[0037] The core equipment of the present invention includes modules such as a nested protection device, a stress monitoring system, and a thermal effect control system. These modules work together to complete the ingot cutting task. The nested protection device is responsible for providing physical protection. The stress monitoring system is used to collect real-time stress distribution data inside the ingot. The thermal effect control system is responsible for dynamically adjusting the cutting speed and coolant flow rate. For example, in a certain actual application scenario, the ingot to be cut is a silicon carbide ingot with a diameter of 100 mm and a length of 200 mm. First, a nested protection device is designed and prepared according to the size of the ingot. The thickness of its inner elastic buffer layer is 1 mm, the unit size of the middle stress dispersion layer is 2 mm, and the thickness of the outer rigid support layer is 4 mm. Subsequently, the ingot is placed in the nested protection device, and the gap between the inner layer and the ingot is adjusted to 0.2 mm. During the cutting process, the stress monitoring system collects real-time stress distribution data inside the ingot and calculates the effective stress value through a finite element analysis algorithm. At the same time, the thermal effect control system dynamically adjusts the cutting speed and coolant flow rate according to the thermal effect management model to ensure that the surface temperature of the ingot is always within the safe range. After cutting, the ingot is subjected to non-destructive testing using ultrasonic detection technology. The results show that there are no hidden defects inside and on the surface of the ingot, and the cutting quality reaches the expected goal.

[0038] In summary, the present invention realizes efficient and high-quality ingot cutting results by precisely controlling the nested structure parameters, the stress distribution optimization algorithm, and the thermal effect management model. This method is particularly suitable for the demand of the third-generation semiconductor industry for high-quality silicon carbide wafers and has important application value and popularization prospects.

[0039] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A nested protection device and method during the ingot cutting process, characterized in that, It includes an inner elastic buffer layer, a middle stress dispersion layer, and an outer rigid support layer. The inner elastic buffer layer is made of a polymer material with a thickness ranging from 0.5 mm to 2 mm. The middle stress dispersion layer is composed of a honeycomb metal grid with a cell size ranging from 1 mm to 3 mm. The outer rigid support layer is made of a high-strength carbon fiber composite material with a thickness ranging from 3 mm to 5 mm.

2. The nested protection device and method during the ingot cutting process according to claim 1, characterized in that, The gap between the inner elastic buffer layer and the ingot to be cut ranges from 0.1 mm to 0.3 mm.

3. The nested protection device and method during the ingot cutting process according to claim 1, characterized in that, The cell shape of the honeycomb metal grid is a regular hexagon.

4. A nested protection method during the ingot cutting process, characterized in that It includes the following steps: Place the ingot to be cut in the nested protection device described in any one of claims 1 to 3, and adjust the gap between the inner elastic buffer layer and the ingot to 0.1 mm to 0.3 mm. Calculate the effective stress value inside the ingot through a stress optimization algorithm based on finite element analysis and adjust the nested structure parameters. At the same time, use the thermal effect management model to dynamically adjust the cutting speed and coolant flow rate to reduce the impact of thermal effects on the ingot.

5. The nested protection method according to claim 4, wherein The calculation formula for the effective stress value is: Among them, σ eff represents the effective stress value, and σ x , σ y , σ z are the principal stresses in three directions respectively, and V is the volume of the ingot.

6. The nested protection method according to claim 4, characterized in that, The calculation formula for the thermal effect management model is: Among them, T max is the maximum temperature on the surface of the ingot, T0 is the initial temperature, Q is the heat input power per unit time, t is the cutting time, k is the thermal conductivity, and A is the heat conduction area.

7. The nested protection method according to claim 4, characterized in that After cutting, perform non-destructive testing on the ingot. The testing methods include ultrasonic testing or X-ray testing.

8. An ingot cutting device, characterized in that, It includes a nested protection device, a stress monitoring system, and a thermal effect control system. The nested protection device is the multi-layer nested structure described in any one of claims 1 to 3. The stress monitoring system is used to collect the stress distribution data inside the ingot in real time. The thermal effect control system is used to dynamically adjust the cutting speed and coolant flow rate according to the thermal effect management model.

9. The ingot cutting device according to claim 8, wherein, The thickness of the inner elastic buffer layer of the nested protection device is 1 mm, the cell size of the middle stress dispersion layer is 2 mm, and the thickness of the outer rigid support layer is 4 mm.

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