Process for controlling heat of ingot cutting

Abstract

The application discloses a process method for controlling the heat of crystal bar cutting, which comprises the following steps: fixing the crystal bar on a workpiece plate with a carbon-based resin plate bonded thereto; and constantly changing the temperature, mortar temperature and flow of a temperature control device arranged in a cutting piece processing bin when the cutting depth of the crystal bar gradually increases; the application can effectively reduce the warp value of the same batch of silicon wafers by comprehensively controlling the heat generated in the crystal bar cutting process through the temperature control device, the carbon-based resin plate and the change of the mortar, the heat change of the crystal bar processing process is controlled by using the carbon-based resin plate and the temperature control device, the temperature control device is timely adjusted along with the change of the cutting depth of the crystal bar and the change of the mortar temperature, the temperature change of the cut-off crystal bar is avoided to be too large, and the problem of unstable heat fluctuation during the cutting of the crystal bar is solved; the heat generated during the processing can be better and more stably controlled by using multiple ways.

Description

Technical Field

[0001] This invention belongs to the field of silicon wafer manufacturing technology, specifically relating to a process method for controlling the heat during crystal rod cutting. Background Technology

[0002] Silicon wafers are the most important semiconductor material; integrated circuit chips and sensors are manufactured based on semiconductor single-crystal silicon wafers. Fluctuations in the supply and price of silicon wafers have a significant impact on the entire IC chip industry. As the foundation of IC development and the ideal substrate material for semiconductor chips, the surface quality of silicon wafers directly affects the performance, yield, and lifespan of IC devices. Therefore, higher requirements are placed on the surface quality of silicon wafers, demanding a damage-free layer, lower roughness, and better flatness. Consequently, the process requirements for manufacturing silicon wafers are gradually increasing.

[0003] The currently accepted international method is to use multi-wire cutting equipment with free abrasive to prepare silicon wafers. This involves processing a crystal ingot into a silicon wafer using steel wires carrying silicon carbide particle slurry. During the cutting process, parameters such as the tension and speed of the steel wire are adjusted to control the warp and bow of the silicon wafer.

[0004] Patent CN115816675A discloses a method for cutting semiconductor crystal rod silicon wafers. Utilizing the liquid damping and high specific heat capacity of slurry, an immersion-type cutting method is used to balance the deformation temperature and vibration of the silicon wafer during the cutting process, thereby reducing the wafer warpage. This invention utilizes the liquid damping and high specific heat capacity of slurry to balance the deformation temperature and vibration of the silicon wafer during the cutting process through an immersion-type cutting method. This reduces the vibration generated during silicon wafer processing, and the heating and cooling processes during silicon wafer processing are slow, maintaining a stable temperature for the silicon wafer, thus reducing the wafer warpage.

[0005] One of the main factors affecting silicon wafer warp during silicon wafer production is heat control during the processing. Most existing cutting processes control heat only through slurry, which results in unstable heat fluctuations. The aforementioned patent controls the heat during silicon wafer production through immersion cutting, thereby reducing silicon wafer warp. However, this method uses a large amount of slurry, making it difficult to control the temperature of the immersion slurry. Furthermore, the silicon powder produced by cutting settles at the bottom of the immersion tank, making it difficult to recover and clean, which causes inconvenience during the cleaning process. Summary of the Invention

[0006] In view of this, the present invention provides a process method for controlling the heat during crystal rod cutting, so as to solve the problem of unstable heat fluctuation during crystal rod cutting in the prior art.

[0007] The technical solution adopted by this invention to solve its technical problem is as follows: This invention provides a process method for controlling the heat during crystal rod cutting, comprising the following steps: S1: Before the crystal rod is processed by the slicing machine, the crystal rod is fixed on the workpiece plate with the resin plate bonded on it. S2: When the crystal rod is processed using a slicing machine, when the crystal rod cutting depth is between 0 and 10%, the temperature of the temperature control device in the slicing processing chamber is controlled at the first preset temperature, the slurry temperature is controlled at the first preset temperature, and the slurry flow rate is controlled at the first preset flow rate; when the crystal rod cutting depth is between 10 and 20%, the slurry temperature is reduced to the second preset temperature at a rate of 0.07 to 0.15℃ / min, the slurry flow rate remains unchanged, and the temperature control device temperature is reduced to the second preset temperature; when the crystal rod cutting depth is between 20 and 70%, the slurry temperature remains unchanged, the slurry flow rate remains unchanged, and the temperature control device temperature remains unchanged; when the crystal rod cutting depth is between 70 and 80%, the slurry temperature is increased to the third preset temperature at a rate of 0.05 to 0.1℃ / min, the slurry flow rate is reduced to the second preset flow rate at a rate of 0.1 to 1L / min, and the temperature control device temperature is increased to the first preset temperature; when the crystal rod cutting depth is between 80 and 100%, the slurry temperature remains unchanged, the slurry flow rate remains unchanged, and the temperature control device temperature remains unchanged; the first preset temperature is higher than the third preset temperature.

[0008] Preferably, the first set temperature is 32°C and the second set temperature is 28°C.

[0009] Preferably, the first preset temperature is 22°C, the second preset temperature is 18°C, and the third preset temperature is 21°C.

[0010] Preferably, the first set flow rate is 160 L / min and the second set flow rate is 140 L / min.

[0011] Preferably, the temperature control device includes a heating plate and an air blowing nozzle. There are two heating plates, which are respectively arranged in the slicing processing chambers on opposite sides of the crystal rod. The air blowing nozzle is arranged in the slicing processing chamber below the crystal rod.

[0012] Preferably, the temperature and flow rate of the mortar are controlled by a spray pipe installed in the slicing processing chamber. There is one spray pipe on each side of the workpiece plate, and the outlet of the spray pipe is located above the crystal rod. A proportional valve for adjusting the flow rate of the spray pipe mortar is provided at the outlet of the spray pipe.

[0013] Preferably, a cold water pipe is provided on the outside of the spray pipe, the cold water pipe is connected to the cooling water pipe inside the slicer, and a proportional valve for adjusting the water flow rate in the cold water pipe is provided at the connection point.

[0014] Preferably, the spray pipe is a telescopic pipe so that the distance between the outlet of the spray pipe mortar and the crystal rod can be kept consistent.

[0015] As can be seen from the above technical solution, the present invention provides a process method for controlling the heat of crystal rod cutting, and its advantages over the prior art are: This invention controls the heat changes during the crystal ingot processing by using a carbon-based resin plate with high thermal conductivity and a temperature control device. The temperature control device is added to the processing area, and adjustments are made in a timely manner as the depth of the ingot cutting and the temperature of the slurry change, ensuring a stable temperature for the cut portion. This prevents excessive temperature fluctuations in the cut ingot, which could lead to excessively high warp values ​​in the prepared silicon wafers. By comprehensively controlling the heat generated during the crystal ingot slicing process through the temperature control device, the carbon-based resin plate, and the control of slurry changes, the warp value of silicon wafers in the same batch can be effectively reduced. This solves the problem of unstable heat fluctuations during existing crystal ingot cutting methods. By controlling the processing heat through multiple methods, better and more stable heat control can be achieved. Attached Figure Description

[0016] Figure 1 These are topographic images of the head, middle, and tail sections of the silicon wafer after it was cut in Experiment Example 1.

[0017] Figure 2 These are proportional topographic images of the head, middle, and tail sections of a cut silicon wafer.

[0018] Figure 3 This is a box plot of the comparative example and experimental example 1.

[0019] Figure 4 This is a box plot of the comparative example and experimental example 2.

[0020] Figure 5 This is a schematic diagram showing the positions of the spray pipes and the temperature control device.

[0021] In the diagram: 1-Workpiece plate, 2-Carbon-based resin plate, 3-Spray pipe, 4-Crystal rod, 5-Steel wire, 6-Heating plate, 7-Air blowing nozzle. Detailed Implementation

[0022] The technical solutions and effects of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0023] This invention provides a process method for controlling the heat during crystal rod cutting, comprising the following steps: S1: Before the crystal rod 4 is processed by the slicing machine, the crystal rod 4 is fixed on the workpiece plate 1 to which the carbon-based resin plate 2 is bonded. S2: When the crystal rod 4 is processed using a slicing machine, when the cutting depth of the crystal rod 4 is between 0 and 10%, the temperature of the temperature control device in the slicing processing chamber is controlled to the first set temperature, the slurry temperature is controlled to the first preset temperature, and the slurry flow rate is controlled to the first set flow rate; when the cutting depth of the crystal rod 4 is between 10 and 20%, the slurry temperature is reduced to the second preset temperature at a rate of 0.07 to 0.15℃ / min, the slurry flow rate remains unchanged, and the temperature of the temperature control device is reduced to the second set temperature; when the cutting depth of the crystal rod 4 is between 20 and 70%, the slurry temperature... The mortar flow rate and the temperature control device temperature remain constant. When the cutting depth of the crystal rod 4 is 70-80%, the mortar temperature is increased to the third preset temperature at a rate of 0.05-0.1℃ / min, the mortar flow rate is decreased to the second preset flow rate at a rate of 0.1-1L / min, and the temperature control device temperature is increased to the first preset temperature. When the cutting depth of the crystal rod 4 is 80-100%, the mortar temperature, the mortar flow rate, and the temperature control device temperature remain constant. The first preset temperature is higher than the third preset temperature.

[0024] In this embodiment, the present invention increases heat conduction during processing by replacing the resin material with low thermal conductivity with a carbon-based resin plate 2 with high thermal conductivity. Existing slicing machines use resin plates with thermal conductivity between 0.2 and 2.2, while the present invention uses a carbon-based resin plate 2 with a thermal conductivity of 129 to 151, which can better conduct heat and thus reduce the temperature during processing. The cutting depth refers to the percentage of the diameter of the crystal rod 4. The temperature of the processing area changes with the cutting area of ​​the crystal rod 4. At the beginning of processing, the temperature of the processing area is low, requiring heating. As the cutting depth gradually increases and the cutting area changes, the temperature of the processing area gradually rises, requiring cooling. When cutting... When the cutting depth is 70-100%, the cutting area of ​​the crystal rod 4 decreases, and the temperature of the processing area gradually decreases. However, the temperature at this time will not be higher than the initial cutting temperature of the crystal rod 4. At this time, heating is required. Therefore, the third preset temperature should be lower than the first preset temperature. This invention adds a temperature control device to the processing area and makes timely adjustments as the cutting depth of the crystal rod 4 changes and the temperature of the slurry changes. This allows the temperature of the cut part to be stably regulated, avoiding excessive temperature changes in the cut crystal rod 4, which would result in an excessively high warp value for the prepared silicon wafer. By comprehensively controlling the heat generated during the crystal rod slicing process through the temperature control device, the carbon-based resin plate 2, and the control of slurry changes, the warp value of the same batch of silicon wafers can be effectively reduced.

[0025] Furthermore, the first set temperature is 32°C, and the second set temperature is 28°C.

[0026] Furthermore, the first preset temperature is 22°C, the second preset temperature is 18°C, and the third preset temperature is 21°C.

[0027] Furthermore, the first set flow rate is 160 L / min, and the second set flow rate is 140 L / min.

[0028] By adjusting the cutting depth of the ingot 4, the process parameters of this invention can be optimized to produce high-quality silicon wafers with low warp values.

[0029] Please refer to Figure 5 In one embodiment, the temperature control device includes a heating plate 6 and an air blowing nozzle 7. Two heating plates 6 are provided and are respectively arranged in the slicing processing chambers on opposite sides of the crystal rod 4. The air blowing nozzle 7 is arranged in the slicing processing chamber below the crystal rod 4.

[0030] In this embodiment, heating plates 6 are used on both sides of the crystal rod 4 to increase the temperature. As the diameter of the crystal rod 4 changes, the temperature rises. Heating plates 6 are used to process the cut part. During the processing, the more heat is generated as the cutting depth increases, the more temperature control is required. Below the vertical crystal rod 4, an air nozzle 7 is used to spray air to cool the crystal rod 4. The air nozzle 7 uses a stable airflow. The cooperation between the two can more accurately and effectively control the heat generated during the slicing process of the crystal rod 4, and avoid the temperature difference between different positions of the same silicon wafer being too large, which would affect the quality of the silicon wafer.

[0031] Please refer to Figure 5 In one embodiment, the temperature and flow rate of the mortar are controlled by a spray pipe 3 installed in the slicing processing chamber. There is one spray pipe 3 on each side of the workbench, and the outlet of the spray pipe 3 is located above the crystal rod 4. A proportional valve for adjusting the flow rate of the spray pipe 3 is provided at the outlet of the spray pipe 3.

[0032] In this embodiment, the temperature of the cutting part of the crystal rod 4 is accurately controlled by the spray pipes 3 set on both sides of the worktable. In the original multi-wire slicing machine, the slurry is sprayed onto the wire mesh of the steel wire 5 above the main roller shaft. The cutting and cooling effect is achieved by the driving of the steel wire 5. In the original technology, because the steel wire 5 moves at a high speed, less slurry is carried, and the cooling effect is small. The present invention changes the spray position of the slurry, so that the cutting part can be cooled quickly and effectively, thereby improving the quality of the prepared silicon wafer.

[0033] In one embodiment, a cold water pipe is provided on the outside of the spray pipe 3. The cold water pipe is connected to the cooling water pipe inside the slicer, and a proportional valve for adjusting the water flow rate in the cold water pipe is provided at the connection point.

[0034] In this embodiment, the mortar temperature is controlled more effectively and conveniently by using cooling water inside the slicer to cool the mortar and adjusting the cooling water in the cold water pipe through a proportional valve.

[0035] In one embodiment, the spray pipe 3 is a telescopic pipe to adjust the distance between the outlet of the mortar in the spray pipe 3 and the crystal rod 4 to always remain consistent.

[0036] In this embodiment, the spray pipe 3 is a telescopic pipe. The position of the spray pipe 3 is changed by an electric push rod, so that the spray pipe 3 can move synchronously with the movement of the crystal rod 4 during the cutting process. This allows the slurry in the spray pipe 3 to spray the cutting position of the crystal rod 4, so as to better use the slurry to control the heat during the cutting process and make the cutting position reach the desired temperature.

[0037] To facilitate understanding, the present invention is further illustrated by the following comparative examples, Experimental Example 1, and Experimental Example 2: Comparative Example This comparative example provides a process method for controlling the heat during crystal rod cutting, including the following steps: S1: Before the crystal rod 4 is processed by the slicing machine, the crystal rod 4 is fixed on the workpiece plate 1 which is bonded with epoxy resin board. S2: When the crystal rod 4 is processed using a slicing machine, when the cutting depth of the crystal rod 4 is 0~10%, the temperature of the slurry sprayed on the cutting steel wire 5 is controlled at 22℃, and the slurry flow rate is controlled at 160L / min; when the cutting depth of the crystal rod 4 is 10~20%, the temperature of the slurry sprayed on the cutting steel wire 5 is controlled at 18℃, and the slurry flow rate remains unchanged; when the cutting depth of the crystal rod 4 is 20~70%, the slurry temperature and the slurry flow rate remain unchanged; when the cutting depth of the crystal rod 4 is 70~80%, the temperature of the slurry sprayed on the cutting steel wire 5 is controlled at 21℃, and the slurry flow rate is controlled at 140L / min; when the cutting depth of the crystal rod 4 is 80~100%, the slurry temperature and the slurry flow rate remain unchanged. The morphology of the head, middle, and tail of the cut silicon wafer is as follows: Figure 2 As shown.

[0038] Experimental Example 1 This experimental example provides a process method for controlling the heat during crystal rod cutting, including the following steps: S1: Before the crystal rod 4 is processed by the slicing machine, the crystal rod 4 is fixed on the workpiece plate 1 to which the carbon-based resin plate 2 is bonded. S2: When the crystal rod 4 is processed using a slicing machine, when the cutting depth of the crystal rod 4 is between 0 and 10%, the temperature of the temperature control device in the slicing processing chamber is controlled at 32℃, the slurry temperature is controlled at 22℃, and the slurry flow rate is controlled at 160L / min; when the cutting depth of the crystal rod 4 is between 10 and 20%, the slurry temperature is reduced to 18℃ at a rate of 0.08℃ / min, the slurry flow rate remains unchanged, and the temperature control device temperature is reduced to 28℃; when the cutting depth of the crystal rod 4 is between 20 and 70%, the slurry temperature, the slurry flow rate, and the temperature control device temperature remain unchanged; when the cutting depth of the crystal rod 4 is between 70 and 80%, the slurry temperature is increased to 21℃ at a rate of 0.05 to 0.1℃ / min, the slurry flow rate is reduced to 140L / min at a rate of 0.1L / min, and the temperature control device temperature is increased to 32℃; when the cutting depth of the crystal rod 4 is between 80 and 100%, the slurry temperature, the slurry flow rate, and the temperature control device temperature remain unchanged. The temperature and flow rate of the mortar are controlled by the spray pipe 3 installed in the slicing processing chamber. There is one spray pipe 3 on each side of the workbench, and the outlet of the spray pipe 3 for the mortar is located above the crystal rod 4. The temperature control device includes a heating plate 6 and an air blowing nozzle 7. There are two heating plates 6, which are respectively installed in the slicing processing chambers on opposite sides of the crystal rod 4. The air blowing nozzle 7 is installed in the slicing processing chamber below the crystal rod 4. The morphology of the head, middle, and tail of the cut silicon wafer is as follows: Figure 1 As shown.

[0039] Experimental Example 2 This comparative example provides a process method for controlling the heat during crystal rod cutting, including the following steps: S1: Before the crystal rod 4 is processed by the slicing machine, the crystal rod 4 is fixed on the workpiece plate 1 to which the carbon-based resin plate 2 is bonded. S2: When the crystal rod 4 is processed using a slicing machine, when the cutting depth of the crystal rod 4 is 0~10%, the temperature of the slurry sprayed on the cutting steel wire 5 is controlled at 22℃, and the slurry flow rate is controlled at 160L / min; when the cutting depth of the crystal rod 4 is 10~20%, the temperature of the slurry sprayed on the cutting steel wire 5 is controlled at 18℃, and the slurry flow rate remains unchanged; when the cutting depth of the crystal rod 4 is 20~70%, the slurry temperature and the slurry flow rate remain unchanged; when the cutting depth of the crystal rod 4 is 70~80%, the temperature of the slurry sprayed on the cutting steel wire 5 is controlled at 21℃, and the slurry flow rate is controlled at 140L / min; when the cutting depth of the crystal rod 4 is 80~100%, the slurry temperature and the slurry flow rate remain unchanged.

[0040] Depend on Figure 4It can be seen that, compared with the comparative data, the average warp value of Experimental Example 2 decreased by about 3µm. Therefore, using carbon-based resin plate 2 can effectively improve the production quality of silicon wafers. In Experimental Example 1, the warp value of silicon wafers was improved by effectively controlling the temperature during the cutting process of crystal ingot 4. Figure 1 , 2 It can be seen that the flatness of the warp 3D topography images of the head, middle, and tail of the silicon wafer cut in Experiment Example 1 is greatly improved compared to the comparative example. Figure 3 It can be seen that the average warp value of the silicon wafer processed by the comparative example is 11.2177um, while the average warp value of the silicon wafer processed by the experimental example is 6.58um. Compared with the data of the comparative example, the average warp value decreased by about 5um. Therefore, the temperature control method set in Experimental Example 1 greatly improved the production quality of silicon wafers.

[0041] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A process method for controlling the heat during crystal rod cutting, characterized in that, Includes the following steps: S1: Before the crystal rod is processed by the slicing machine, the crystal rod is fixed on the workpiece plate with the carbon-based resin plate bonded on it. S2: When the crystal rod is processed using a slicing machine, when the crystal rod cutting depth is between 0 and 10%, the temperature of the temperature control device in the slicing processing chamber is controlled at the first preset temperature, the slurry temperature is controlled at the first preset temperature, and the slurry flow rate is controlled at the first preset flow rate; when the crystal rod cutting depth is between 10 and 20%, the slurry temperature is reduced to the second preset temperature at a rate of 0.07 to 0.15℃ / min, the slurry flow rate remains unchanged, and the temperature control device temperature is reduced to the second preset temperature; when the crystal rod cutting depth is between 20 and 70%, the slurry temperature remains unchanged, the slurry flow rate remains unchanged, and the temperature control device temperature remains unchanged; when the crystal rod cutting depth is between 70 and 80%, the slurry temperature is increased to the third preset temperature at a rate of 0.05 to 0.1℃ / min, the slurry flow rate is reduced to the second preset flow rate at a rate of 0.1 to 1L / min, and the temperature control device temperature is increased to the first preset temperature; when the crystal rod cutting depth is between 80 and 100%, the slurry temperature remains unchanged, the slurry flow rate remains unchanged, and the temperature control device temperature remains unchanged; the first preset temperature is higher than the third preset temperature. The first set temperature is 32°C, and the second set temperature is 28°C; The first preset temperature is 22°C, the second preset temperature is 18°C, and the third preset temperature is 21°C; The first set flow rate is 160 L / min, and the second set flow rate is 140 L / min.

2. The process method for controlling the heat during crystal rod cutting as described in claim 1, characterized in that, The temperature control device includes a heating plate and an air blowing nozzle. There are two heating plates, which are respectively installed in the slicing processing chambers on opposite sides of the crystal rod. The air blowing nozzle is installed in the slicing processing chamber below the crystal rod.

3. The process method for controlling the heat during crystal rod cutting as described in claim 1, characterized in that, The temperature and flow rate of the mortar are controlled by a spray pipe installed in the slicing processing chamber. There is one spray pipe on each side of the processing table, and the outlet of the spray pipe is located above the crystal rod. A proportional valve for adjusting the flow rate of the spray pipe is provided at the outlet of the spray pipe.

4. The process method for controlling the heat during crystal rod cutting as described in claim 3, characterized in that, A cold water pipe is provided on the outside of the spray pipe. The cold water pipe is connected to the cooling water pipe inside the slicer, and a proportional valve for adjusting the water flow rate in the cold water pipe is provided at the connection point.

5. The process method for controlling the heat during crystal rod cutting as described in claim 3, characterized in that, The spray pipe is a telescopic pipe to ensure that the distance between the mortar outlet and the crystal rod remains consistent.

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