Cylindrical grinding method and cylindrical grinder

Abstract

The present invention is a cylindrical grinding method for cylindrically grinding a crystal ingot, wherein: a support device having a concave-shaped support section able to support a conical end of the crystal ingot is used as a support device; a cylindrical grinder equipped with a remaining state determining means for determining whether part of the conical end of the crystal ingot remains inside the support section is used as a cylindrical grinder; and in continuous processing of the cylindrical grinding, continuous processing is maintained if the remaining state determining means determines that no part of the end is remaining inside the support section, and the continuous processing is stopped if it is determined that part of the end is remaining. Provided thereby are a cylindrical grinding method and a cylindrical grinder making it possible to reliably find it out if a distal end of a conical tail part is remaining inside the support device in an unloading step after a silicon single crystal ingot has been subjected to cylindrical grinding.

Description

Cylindrical grinding method and cylindrical grinding machine

[0001] The present invention relates to a cylindrical grinding method and a cylindrical grinding machine.

[0002] In recent years, the diameter of wafers used in semiconductor device manufacturing has been increasing in order to improve the performance of semiconductor devices and reduce manufacturing costs. The wafers used in semiconductor device manufacturing are produced by preparing a crystal rod using the Czochralski method or other methods, with a conical cone and tail at the axial end of a cylindrical body. The outer periphery of the crystal rod is then cylindrically ground using a cylindrical grinder, and the rod is sliced ​​perpendicular to the axial direction to cut into plates, which are then polished. In recent years, as the number of wafers obtained from a single crystal rod increases and the diameter of the wafers increases, the crystal rods produced have also become longer, larger in diameter, and heavier.

[0003] When cylindrically grinding such crystal rods, a typical cylindrical grinding machine is composed of a transport unit for transporting the crystal rod in and out of the machine, a support unit for holding the crystal rod, and a grinding unit for cylindrically grinding the outer periphery of the crystal rod. Figure 3 shows a schematic diagram of a crystal rod held in a typical cylindrical grinding machine (transport stage), and Figure 4 shows a schematic diagram of a crystal rod held in a typical cylindrical grinding machine (grinding stage).

[0004] The crystal rod 51 is composed of a cylindrical body portion 52, cone portions 53 at both ends of the cylindrical body portion, and a tail portion 54. The crystal rod 51 is transported into the cylindrical grinding machine by a transport unit 13. The cylindrical grinding machine 101 generally has a support unit (first support unit) 4a and a support unit (second support unit) 4b, on which support devices 2a and 2b are installed via a main shaft 3a and a sub-shaft 3b for rotating the crystal rod 51. The first support unit 4a on the main shaft side is fixed, while the second support unit 4b on the sub-shaft side is movable by a drive mechanism (not shown) such as a servo motor, thereby sandwiching the crystal rod 51 between the first support unit 4a and the second support unit 4b in the crystal axis direction. The cylindrical surface of the crystal rod 51 is ground using a grinding wheel 6 in the grinding unit 5.

[0005] Japanese Patent Application Laid-Open No. 2023-173377

[0006] 5 shows a dislocation-free crystal rod 51a. The cone and tail portions at both ends of the crystal rod are conical (conical cone portion 53a, conical tail portion 54a).

[0007] Figure 6 shows a crystal bar 51b that has undergone dislocations during growth. In this case, if the crystal bar 51b is clamped and fixed axially by the support devices 2a and 2b, the dislocation region SL collapses, resulting in a problem of being unable to be fixed properly. Therefore, as a pretreatment step, the dislocation region SL is cut perpendicular to the crystal axis using a band saw or the like, and the dislocation region SL is made into a flat surface 54b as shown in Figure 7, after which cylindrical grinding is performed. Furthermore, if the cone region 53a is cut into a flat surface 53b, the result will be as shown in Figure 8.

[0008] As shown in FIG. 2, the support devices 2a and 2b include a support portion (first support portion) 11 having a conical hole, and a support portion (second support portion) 12 that supports the vertically cut flat surfaces 53b and 54b.

[0009] The conical cone portion 53a and the conical tail portion 54a are supported by a first support portion 11 having a conical hole, as shown in Fig. 9. The flat surface 53b where the cone portion is cut and the flat surface 54b where the dislocation-containing portion or the tail portion is cut are supported by a second support portion 12, as shown in Fig. 10. The second support portion 12 is designed to have a small range of movement in all directions so that it can hold the crystal ingot horizontally even if it is not possible to cut the crystal ingot exactly perpendicular to the axial direction during preprocessing.

[0010] Next, the preparation process for cylindrical grinding (loading process) will be described using Figures 11 to 14, in which the crystal rod 51 is transported into the cylindrical grinding machine 101 by the transport unit 13 and the crystal rod 51 is clamped in the crystal axis direction by the first support unit 4a and the second support unit 4b.

[0011] [Transporting the Crystal Bar] As shown in FIG. 11, the conveying unit 13, which holds the crystal bar 51 in the diametrical direction, moves the crystal bar 51 so that the crystal axis center 15 coincides with the rotation center 14 of the main shaft 3a and the sub-shaft 3b.

[0012] [Support of the Crystal Bar] The crystal bar 51 is sandwiched between the first support unit 4a and the second support unit 4b. In the cylindrical grinding machine 101, the first support unit 4a on the main shaft 3a side is generally fixed, and the second support unit 4b on the sub-shaft 3b side is moved by a drive mechanism such as a servo motor.

[0013] The support device 2b of the second support unit 4b on the countershaft 3b, which is continuously moved toward the main shaft 3a by a drive mechanism such as a servo motor, contacts the conical tail portion 54a or dislocation portion of the crystal rod 51, or the flat surface 54b where the tail portion is cut, as shown in Figure 12, and continues to move toward the main shaft 3a together with the transport unit 13 sandwiching the crystal rod 51 in the diametric direction. As shown in Figure 13, the support device 2a of the first support unit 4a contacts the conical cone portion 53a of the crystal rod 51 or the flat surface 53b where the cone portion is cut, and the crystal rod 51 is sandwiched and supported between the support device 2a on the main shaft 3a and the support device 2b on the countershaft 3b.

[0014] In the subsequent cylindrical grinding process, when the cylindrical surface of the crystal rod 51 is ground with the grinding wheel 6 of the grinding unit 5, it is necessary to prevent the support devices 2a, 2b from slipping on the conical cone portion 53a or the conical tail portion 54a due to grinding resistance.Therefore, after the crystal rod 51 is sandwiched and supported between the support devices 2a, 2b, the second support unit 4b continues to move toward the main shaft 3a, generating a pressing force 16 and increasing the friction force between the conical cone portion 53a and the conical tail portion 54a of the crystal rod 51 and the support devices 2a, 2b that come into contact with them.

[0015] [Retraction of the Transport Unit] After the crystal bar 51 is sandwiched between the first and second support units 4a and 4b in the crystal axis direction, the transport unit 13 releases the crystal bar 51 and retracts as shown in FIG.

[0016] Next, we will explain the problems that arise due to differences in the shape of the tail. Figure 15 shows the tail of a dislocation-free crystal rod. Parameters that characterize the tail include the diameter D of the straight body (i.e., the diameter of the starting part of the tail) and the length L of the conical tail. The cone angle θ is a parameter that can also be calculated from D and L.

[0017] The conical tail portion 54a, which is particularly affected by the shape, will be described with reference to Figures 16 and 17. For example, as shown in Figure 16, even if the diameter D of the straight body portion of the crystal ingot 51 is the same, the length L of the conical tail portion may differ. Specifically, when the diameters D1 and D2 of the straight body portion are the same (D1 = D2), but the length L2 of the conical tail portion is longer than L1 (L1 < L2), the cone angle θ2 is smaller than θ1 (θ1 > θ2), resulting in a pronounced pointed shape. Also, in Figure 17, the lengths L3 and L4 of the conical tail portion are the same (L3 = L4), but when the diameter D4 of the straight body portion is smaller than D3 (D3 > D4), the cone angle θ4 is smaller than θ3 (θ3 > θ4), resulting in a pronounced pointed shape.

[0018] As described above, the conical tail portion 54a of the crystal rod 51 is supported by contacting and sandwiching it with the support device 2b, but even if a cylindrical grinding machine is prepared specifically for processing crystal rods with the same straight body diameter D, the same support device 2b will support conical tail portions 54a of various shapes with different conical tail lengths L. Furthermore, since it is common to process crystal rods with straight body portions of various diameters D to prevent a decrease in the operating rate of the cylindrical grinding machine, even more shapes of conical tail portions 54a will be supported by the same support device 2b.

[0019] If the conical tail portions 54a of various shapes are supported by the same support device 2b as described above, when the cylindrical surface of the crystal rod 51 is ground using the grinding unit 5 and grinding wheel 6 in the subsequent cylindrical grinding process, the conical tail portion 54a may break at the contact portion 17 between the first support portion 11 of the support device 2b and the conical tail portion 54a, as shown in Figure 18(a).

[0020] When the crystal bar 51 is removed from the machine after the cylindrical grinding process and other processes are completed, an unloading process is performed, which is the reverse of the loading process. The crystal bar 51, which is sandwiched in the crystal axis direction between the first support unit 4a and the second support unit 4b, is then sandwiched in the diameter direction by the transport unit 13. The second support unit 4b is then moved in the opposite direction to that during the loading process by a drive mechanism such as a servo motor, and contact between the first support unit 4a, the crystal bar 51, and the second support unit 4b is released. The transport unit 13 then transports the crystal bar 51 out of the machine.

[0021] At this time, as shown in FIG. 18(b), the tip 18 of the conical tail portion that breaks off at the contact portion 17 between the first support portion 11 of the support device 2b and the conical tail portion 54a is left behind inside the support device 2b.

[0022] Generally, cylindrical grinding machines are often automated to improve operation rates, and the automatic loading process for processing the next crystal rod begins even if the tip 18 of the broken conical tail portion remains in the support device 2b. In this case, as shown in FIG. 19 , the conical tail portion 54a of the new crystal rod 51 comes into contact with the tip 18 of the broken conical tail portion left behind in the support device 2b. Furthermore, the second support unit 4b continues to move toward the spindle 3a to increase the friction between the cone portion 53a or flat surface 53b and tail portion 54a of the crystal rod 51 and the support devices 2a and 2b where they contact, exerting a pressing force 16. Because the tip of the conical tail portion 54a of the crystal rod 51 is in contact with the tip 18 of the broken conical tail portion left behind in the support device 2b, it may collapse due to the pressing force 16. This may also damage the support device 2b and the second support unit 4b or cause assembly inaccuracies, resulting in poor quality or damage to the crystal rod 51.

[0023] The problem of the conical tail portion being broken and left behind in the support device 2b occurs relatively frequently in crystal rods with a small cone angle θ of the conical tail portion 54a (crystal rods with a large cone angle L or a small diameter D of the straight body portion). Figure 20 is a schematic diagram showing a conical tail portion 54a with a large cone angle (θ5) and a conical tail portion 54a with a small cone angle (θ6) being held by the first support portion 11 of the support device 2b. In this diagram, the diameter d2 of the conical tail portion 54a with a cone angle θ6 at the contact portion 17 with the first support portion 11 is smaller than the diameter d1 of the conical tail portion 54a with a cone angle θ5 at the contact portion 17 with the first support portion 11. Therefore, one reason for this is that crystal rods with a small cone angle θ of the conical tail portion 54a are more susceptible to external forces at the contact portion 17 than crystal rods with a large cone angle θ, but there are other possible causes.

[0024] Figure 21 shows a crystal rod in which the axial center 19 of the conical tail portion 54a does not coincide with the crystal axis center 15 for some reason. Figure 22 shows a state in which the axial center 19 of the conical tail portion 54a coincides with the crystal axis center 15, but when the crystal rod 51 is clamped in the diametric direction by the transport unit 13, the rotation center 14 of the main shaft 3a and the sub-shaft 3b does not coincide with the crystal axis center 15 (19) due to the influence of the uneven surface of the straight body portion 52. In both cases, during the loading process, the second support unit 4b continues to move toward the main shaft, and the cone portion 53a and the conical tail portion 54a of the crystal rod 51 come into contact with the first support portion 11 of the support device 2a, 2b. When a pressing force 16 is applied, stress is generated in the diametric direction at the contact portion 17.

[0025] Furthermore, even if the tail portion 54 of the crystal rod 51 has a conical shape, it is rare that dislocations occur internally. In this case, when the cone portion 53 and the conical tail portion 54a of the crystal rod 51 come into contact with the first support portion 11 of the support device 2b and a pressing force 16 is applied, it is easy to imagine that the partially dislocated conical tail portion 54a will break or collapse.

[0026] From the above, if the conical tail breaks at the contact area 17 between the first support part 11 of the support device 2b and the conical tail part 54a and is left behind in the support device 2b, there is a high probability of quality defects or damage occurring, but it is extremely difficult to prevent the conical tail part from breaking at the contact area 17. For this reason, the shape of the conical tail part 54a of the crystal rod 51 is checked in advance by an operator, and if it is determined that the conical tail part 54a is likely to break during processing, the crystal rod is manually processed and then checked to see if the conical tail part 54a is broken, thereby reducing the operating rate of the device.

[0027] Patent Document 1 discloses a cylindrical grinding machine that can detect both ends of a crystal rod (the conical cone portion and the tail portion) during the preparation process (loading process) for cylindrically grinding the crystal rod, thereby safely and quickly clamping and supporting the crystal rod in the axial direction. However, it does not address the problem of the tip of the tail portion breaking off during processing and remaining inside the support device.

[0028] The present invention has been made to solve the above problems, and has an object to provide a cylindrical grinding method and cylindrical grinding machine that can reliably detect the tip of a conical tail portion remaining in a support device during the unloading process after cylindrical grinding a silicon single crystal ingot, thereby preventing quality defects and damage to the device.

[0029] The present invention has been made to achieve the above-mentioned object, and provides a cylindrical grinding method for cylindrically grinding a crystal rod using a cylindrical grinding machine comprising a pair of support units, each of which has a main shaft and a sub-shaft attached to the tip of a support device that supports the end of the crystal rod, sandwiching the crystal rod in the axial direction via the main shaft and sub-shaft, allowing it to rotate around the axis, and a grinding unit that moves along the axial direction of the crystal rod supported by the pair of support units to cylindrically grind the outer periphery of the crystal rod, wherein the support device has a concave support portion that can support the conical end of the crystal rod, and the cylindrical grinding machine is equipped with a remaining state determination means that determines whether a portion of the conical end of the crystal rod remains within the support portion, and the cylindrical grinding method is characterized in that, during the continuous cylindrical grinding process, if the remaining state determination means determines that a portion of the end does not remain within the support portion, the continuous process is continued, and if it determines that a portion of the end remains, the continuous process is stopped.

[0030] According to this cylindrical grinding method, if the tip of the conical tail portion remains in the support device during the unloading process after cylindrically grinding the silicon single crystal ingot, this can be reliably detected, and quality defects and damage to the device can be prevented.

[0031] In this case, the remaining state determination means can make a determination by acquiring images of the conical end of the crystal rod before and after the cylindrical grinding, comparing the images, and if it is determined that the conical end of the crystal rod is missing after the cylindrical grinding, determining that a portion of the conical end of the crystal rod remains within the support portion.

[0032] This makes it possible to more reliably find the tip of the conical tail portion remaining in the support device.

[0033] In this case, the remaining state determination means can make a determination by supplying compressed air to the space surrounded by a portion of the conical end of the crystal rod and the support portion, and when a pressure sensor detects an increase in pressure in the space, it determines that a portion of the conical end of the crystal rod remains within the support portion.

[0034] This makes it possible to more reliably find the tip of the conical tail portion remaining in the support device.

[0035] At this time, the continuous processing can be stopped automatically.

[0036] This allows the continuous processing to be stopped automatically without human intervention if the tip of the conical tail remains inside the support device.

[0037] The present invention has also been made to achieve the above-mentioned object, and provides a cylindrical grinding machine comprising a pair of support units that sandwich the crystal rod in the axial direction via a main shaft and a sub-shaft attached to the tip of each support device that support the end of the crystal rod, allowing it to rotate around the axis, and a grinding unit that cylindrically grinds the outer periphery of the crystal rod while moving along the axial direction of the crystal rod supported by the pair of support units, wherein the support device has a concave support portion that can support the conical end of the crystal rod, and the cylindrical grinding machine is equipped with a remaining state determination means that determines whether part of the conical end of the crystal rod remains within the support portion, and the remaining state determination means has the function of determining whether part of the conical end of the crystal rod remains within the support portion during the continuous cylindrical grinding process, and emitting a determination signal if it is determined that part remains.

[0038] With such a cylindrical grinding machine, if the tip of the conical tail portion remains inside the support device during the unloading process after cylindrical grinding of the silicon single crystal ingot, it is possible to reliably detect this and prevent quality defects and damage to the device.

[0039] In this case, the remaining state determination means has an image capturing unit and a defect determination unit, and the image capturing unit has the function of acquiring images of the conical end of the crystal rod before and after the cylindrical grinding, and when the defect determination unit compares the images and determines that the conical end of the crystal rod is defective after the cylindrical grinding, it has the function of determining that a portion of the conical end of the crystal rod remains within the support portion.

[0040] This makes it possible to more reliably find the tip of the conical tail portion remaining in the support device.

[0041] In this case, the remaining state determination means can have a compressed air supply unit and a pressure sensor, and the compressed air supply unit has the function of supplying compressed air into the support unit, and the pressure sensor has the function of detecting an increase in pressure within the support unit and, when an increase in pressure is detected, determining that a portion of the conical end of the crystal rod remains within the support unit.

[0042] This makes it possible to more reliably find the tip of the conical tail portion remaining in the support device.

[0043] In this case, the cylindrical grinding machine may be provided with an automatic stopping means having the function of automatically stopping the continuous processing when the remaining state determining means determines that a portion of the conical end of the crystal rod remains within the support portion.

[0044] This makes it possible to automatically stop continuous processing without human intervention if the tip of the conical tail remains inside the support device.

[0045] As described above, according to the cylindrical grinding method of the present invention, if the tip of the conical tail portion remains in the support device during the unloading process after cylindrical grinding of the silicon single crystal ingot, it is possible to reliably detect this and prevent quality defects and damage to the device.

[0046] Furthermore, according to the cylindrical grinding machine of the present invention, if the tip of the conical tail portion remains in the support device during the unloading process after cylindrical grinding of the silicon single crystal ingot, this can be reliably detected, thereby preventing quality defects and damage to the device.

[0047] FIG. 1 shows a schematic diagram of an example of a cylindrical grinding machine according to the present invention; FIG. 2 shows the internal structure of a support device; FIG. 3 shows a schematic diagram of a crystal rod held in a general cylindrical grinding machine (transportation stage); FIG. 4 shows a schematic diagram of a crystal rod held in a general cylindrical grinding machine (grinding stage); FIG. 5 shows a dislocation-free crystal rod; FIG. 6 shows a crystal rod that has become dislocated during growth; FIG. 7 shows a crystal rod with the dislocation-containing portion cut off; FIG. 8 shows a crystal rod with the cone and tail cut off; FIG. 9 shows a schematic diagram of a conical cone or conical tail supported by a first support; FIG. 10 shows a schematic diagram of a crystal rod with both ends supported by a second support, resulting in a flat surface; FIG. 11 shows a schematic diagram of a crystal rod loading process (when the crystal rod is being carried in); FIG. 12 shows a schematic diagram of a crystal rod loading process (when the tail portion is being held); FIG. 13 shows a schematic diagram of a crystal rod loading process (when the cone portion is being held); FIG. 14 shows a schematic diagram of a crystal rod loading process (when the transport unit is being retracted). 23 shows the tail of a dislocation-free crystal rod. 24 shows a conical tail (with the same diameter of the straight body). 25 shows a conical tail (with the same length of the conical tail). 26 shows a state in which a conical tail breaks off at the contact point between the first support and the conical tail, remaining in the support device. 27 shows a state in which a new crystal rod is being loaded with the tip of the broken conical tail remaining in the support device. 28 shows a state in which conical tails with different cone angles are held by the first support. 29 shows a crystal rod in which the axis center of the conical tail does not coincide with the center of the crystal axis. 29 shows a state in which the rotation centers of the main and secondary axes do not coincide with the center of the crystal axis. 21 shows an example of a non-contact detection means in which a conical tail detection sensor is installed in the support device. 21 shows a schematic diagram of a remaining state determination means having a compressed air supply unit and a pressure sensor. 22 shows the state in which the tip of the conical tail remaining in the support device is detected by the non-contact detection means of FIG. 23. 25 shows how the tip of the conical tail portion remaining in the support device is detected by the remaining state determination means of FIG. 24. FIG. 26 is a schematic diagram showing how the cone portion and tail portion of the crystal rod are detected by the end detection sensor (before passing the sensor). FIG. 27 is a schematic diagram showing how the cone portion and tail portion of the crystal rod are detected by the end detection sensor (when in contact with the sensor). FIG. 28 is a schematic diagram showing how the cone portion and tail portion of the crystal rod are detected by the end detection sensor (when passing the sensor). FIG. 29 is a schematic diagram of another example of a cylindrical grinding machine according to the present invention.

[0048] The present invention will be described in detail below, but the present invention is not limited thereto.

[0049] As described above, there has been a demand for a cylindrical grinding method and a cylindrical grinding machine that can reliably detect the tip of a conical tail portion remaining in a support device during the unloading process (unloading process) after cylindrical grinding a silicon single crystal ingot, thereby preventing quality defects and damage to the device.

[0050] As a result of extensive research into the above-mentioned problems, the inventors have come up with a cylindrical grinding method for cylindrically grinding a crystal rod using a cylindrical grinding machine comprising a pair of support units that axially sandwich the crystal rod via a main shaft and a sub-shaft attached to the tip of each support device that supports the end of the crystal rod, allowing the crystal rod to rotate around the axis, and a grinding unit that moves along the axial direction of the crystal rod supported by the pair of support units to cylindrically grind the outer periphery of the crystal rod, wherein the support device has a concave support portion that can support the conical end of the crystal rod, and the cylindrical grinding machine uses a support device that has a concave support portion that can support the conical end of the crystal rod, and the conical end of the crystal rod is partially recessed within the support portion. The inventors have found that a cylindrical grinding method using a cylindrical grinding machine equipped with a remaining state determination means for determining whether a part of the end portion remains in the support portion, continuing the continuous cylindrical grinding process if the remaining state determination means determines that no part of the end portion remains in the support portion, and stopping the continuous cylindrical grinding process if it determines that a part of the end portion remains, can reliably detect the tip of a conical tail portion remaining in the support device in the unloading process after cylindrical grinding of a silicon single crystal ingot, thereby preventing quality defects and damage to the device, and have completed the present invention.

[0051] The inventors have also conducted extensive research into the above-mentioned problems, and as a result have come up with a cylindrical grinding machine comprising a pair of support units that axially sandwich the crystal rod via a main shaft and a sub-shaft attached to the tip of each support device that supports the end of the crystal rod, allowing it to rotate around the axis, and a grinding unit that moves along the axial direction of the crystal rod supported by the pair of support units to cylindrically grind the outer periphery of the crystal rod, wherein the support device has a concave support portion that can support the conical end of the crystal rod, and the cylindrical grinding machine determines whether or not a part of the conical end of the crystal rod remains within the support portion. The inventors have found that a cylindrical grinding machine comprising a remaining state determination means for determining whether a part of the conical end of the crystal rod remains within the support part during the continuous cylindrical grinding process, and for emitting a determination signal when it is determined that a part remains, can reliably detect the tip of the conical tail part remaining within the support device during the unloading process after cylindrical grinding of a silicon single crystal ingot, thereby preventing quality defects and damage to the device, and have completed the present invention.

[0052] 1, 2, and 30, a cylindrical grinding machine 1 according to the present invention will be described. As shown in Figures 1 and 30, the cylindrical grinding machine 1 according to the present invention includes a pair of support units 4a and 4b, each of which has a main shaft 3a and a sub-shaft 3b attached to the tip of support devices 2a and 2b for supporting the end of a crystal rod (such as a silicon single crystal ingot) 51. The support units 4a and 4b axially sandwich the crystal rod via the main shaft 3a and the sub-shaft 3b, allowing the crystal rod to rotate about the axis. The grinding unit 5, which moves along the axial direction of the crystal rod supported (fixed) by the pair of support units 4a and 4b, performs cylindrical grinding of the outer periphery of the crystal rod. The cylindrical grinding machine 1 also includes a remaining condition determination means 7 near the support device 2b for determining whether a portion of the conical end of the crystal rod remains within the support portion 11 shown in Figure 2.

[0053] The support devices 2a and 2b have a concave support portion (first support portion) 11 capable of supporting the conical end of the crystal rod 51. The support devices may also have a second support portion 12 so that they can support the end of the crystal rod even if it has a flat surface.

[0054] In addition, the remaining state determination means 7 has the function of determining whether a part (tip) of the conical end of the crystal rod remains within the support part 11 during the continuous cylindrical grinding process, and emitting a determination signal if it is determined that a part (tip) remains.

[0055] The above-mentioned determination signal may be, for example, an alarm sound or light emitted by the remaining state determination means 7 itself, and / or may be an electrical signal sent to a device connected to the remaining state determination means 7.

[0056] The remaining state determination means 7 may be installed near the support device 2a and may have a function to detect when the end of the crystal rod approaches a desired position.

[0057] With such a cylindrical grinding machine, if the tip of the conical tail portion remains inside the support device during the unloading process after cylindrical grinding of the silicon single crystal ingot, it is possible to reliably detect this and prevent quality defects and damage to the device.

[0058] As shown in Figure 1, the remaining condition determination means 7 may have an image capturing unit 8 and a defect determination unit 9. The image capturing unit 8 has a function of acquiring images of the conical end of the crystal rod before and after cylindrical grinding, and the remaining condition determination means 7 may have a function of determining that a portion of the conical end of the crystal rod remains when the defect determination unit 9 compares the images and determines that the conical end of the crystal rod after cylindrical grinding is defective.

[0059] This makes it possible to more reliably find the tip of the conical tail portion remaining in the support device.

[0060] Figures 27 to 29 are schematic diagrams showing a technology in which an end detection sensor 26 is installed near the outside of the support device 2b, and when the cone portion 53 and tail portion 54 of the crystal rod 51 intercept the end center detection line 27 before entering the support devices 2a and 2b, the cone portion 53 and tail portion 54 are detected, thereby shortening the loading process time.

[0061] In the cylindrical grinding machine of the present invention, an end detection sensor 26 may be installed near the support device, and as shown in Figures 28 and 29, when the conical ends 53a, 54a of the crystal rod or the flat ends 53b, 54b of the crystal rod interrupt the sensor detection line 27, the end detection sensor 26 may detect them.

[0062] An image sensor 28 may be used as the remaining state determination means 7. The image sensor 28 is installed near the end detection sensor 26 and has the function of distinguishing the conical tail portion 54a and the dislocation portion or the flat surface 54b where the tail portion is cut off when the end detection sensor 26 detects the end of the crystal rod. In the unloading process, the crystal rod 51 is clamped in the diameter direction by the transport unit 13, and when the second support unit 4b is moved and retracted by a drive mechanism such as a servo motor, the image sensor 28 compares the image taken during the loading process with the image taken during the loading process. If the conical tail portion is left behind in the breaking support device 2b, the conical shape will be different, so the difference in the image can be identified, making it possible to determine that the tail portion is left behind in the support device 2b.

[0063] 30, the remaining state determination means 7 may include a compressed air supply unit 29 and a pressure sensor 24. The compressed air supply unit 29 has a function of supplying compressed air into the support unit, and the pressure sensor 24 has a function of detecting an increase in pressure inside the support unit and, when an increase in pressure is detected, determining that a part of the conical end of the crystal rod remains inside the support unit.

[0064] This makes it possible to more reliably find the tip of the conical tail portion remaining in the support device.

[0065] As shown in FIGS. 1 and 30, the cylindrical grinding machine according to the present invention may also be provided with an automatic stopping means 10 that automatically stops continuous processing when the remaining state determining means 7 determines that a portion of the conical end of the crystal bar remains within the support portion.

[0066] This makes it possible to automatically stop continuous processing without human intervention if the tip of the conical tail remains inside the support device.

[0067] [Cylindrical Grinding Method] The present invention also provides a cylindrical grinding method using the cylindrical grinding machine of the present invention as described above, characterized in that, during continuous cylindrical grinding processing, if the remaining state determination means 7 determines that no part of the end of the crystal bar remains in the support part, the continuous processing is continued, and if it determines that part of the end of the crystal bar remains, the continuous processing is stopped.

[0068] According to this cylindrical grinding method, if the tip of the conical tail portion remains in the support device during the unloading process after cylindrically grinding the silicon single crystal ingot, this can be reliably detected, and quality defects and damage to the device can be prevented.

[0069] In this case, the remaining state determination means 7 can make a determination by acquiring images of the conical end of the crystal rod before and after cylindrical grinding, comparing the images, and if it is determined that the conical end of the crystal rod is missing after cylindrical grinding, determining that a portion of the conical end of the crystal rod remains within the support portion.

[0070] This makes it possible to more reliably find the tip of the conical tail portion remaining in the support device.

[0071] In addition, the remaining state determination means 7 can make a determination by supplying compressed air to the space surrounded by a portion of the conical end of the crystal rod and the support portion, and when the pressure sensor 24 detects an increase in the pressure in the space, it determines that a portion of the conical end of the crystal rod remains within the support portion.

[0072] Figure 24 is a schematic diagram showing a remaining state determination means 7 having a pressure sensor 24 and a compressed air supply unit 29 capable of supplying compressed air 25 installed on the first support unit 11 of the support device 2a, 2b, and shows how the conical tail unit 54a of the crystal rod 51 comes into contact with the first support unit 11, closing off the compressed air 25, thereby detecting the conical tail unit 54a with the pressure sensor 24.

[0073] As shown in Figure 26, if the conical tail portion breaks off and is left behind in the support device 2b, during the unloading process, the crystal rod 51 is clamped diametrically by the conveying unit 13, and after the second support unit 4b moves and retreats using a drive mechanism such as a servo motor, the pressure sensor 24 detects an increase in pressure in the space enclosed by the broken conical tail portion 18, thereby detecting the broken conical tail portion 18.

[0074] This makes it possible to more reliably find the tip of the conical tail portion remaining in the support device.

[0075] At this time, the continuous processing can be stopped automatically.

[0076] This allows the continuous processing to be stopped automatically without human intervention if the tip of the conical tail remains inside the support device.

[0077] In addition to the above, a non-contact detection means may be used, in which a sensor installation hole 21 is provided in the first support part 11 in the support device 2a, 2b and a cone part detection sensor 22 is installed in the sensor installation hole 21, as shown in Figure 23. The cone-shaped tail part 54a of the crystal rod 51 interrupts the sensor detection line 23, allowing it to be detected by the cone part detection sensor 22.

[0078] As shown in Figure 25, if the conical tail portion breaks off and is left behind in the support device 2b, during the unloading process, the crystal rod 51 is clamped diametrically by the conveying unit 13, and after the second support unit 4b moves and retreats using a drive mechanism such as a servo motor, the broken conical tail portion 18 will interrupt the sensor detection line 23, making it possible to detect the broken conical tail portion 18.

[0079] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0080] Example 1 Using a cylindrical grinding machine as shown in FIG. 1 and a non-contact detector for detecting the tail portion of the crystal bar as shown in FIG. 27, a total of 100 crystal bars were machined using the same cylindrical grinding machine: 50 crystal bars with a diameter of 300 mm and a length of the straight body portion of 1,000 mm to 1,500 mm, and 50 crystal bars with a diameter of 200 mm and a length of the straight body portion of 1,000 mm to 1,500 mm.

[0081] After the processing was completed, the images of the conical tail 54a during the loading process and the unloading process were compared to determine whether any of the conical tails 54a had broken off and been left behind in the support device 2b. If any of the conical tails 54a had been left behind, an alarm sounded and the device automatically stopped. In addition, to verify the method (device) of the present invention, an operator checked each piece to see if any of the conical tails 54a had broken off and been left behind in the support device 2b.

[0082] The cylindrical grinding machine used in Example 1 was set up to process crystal bars with diameters of 300 mm and 200 mm. In Example 1, the length L of the conical tail portion 54a of the crystal bar was randomly selected to verify whether the cylindrical grinding machine used in Example 1 would automatically stop if the conical tail portion 54a was left behind in the bending support device 2b.

[0083] The length L of the conical cone portion 53a of the crystal rod 51 that is normally manufactured is short and hardly ever breaks, so verification of the cone portion was not performed.

[0084] The results of Example 1 are shown in Table 1.

[0085]

[0086] Example 2 Using a cylindrical grinding machine such as that shown in FIG. 1 and a non-contact detector for detecting the tail portion of the crystal bar shown in FIG. 27, a total of 150 crystal bars were machined on the same cylindrical grinding machine: 50 crystal bars with a diameter of 200 mm and a straight body length of 1,000 mm to 1,500 mm, 50 crystal bars with a diameter of 150 mm and a straight body length of 1,000 mm to 1,500 mm, and 50 crystal bars with a diameter of 125 mm and a straight body length of 1,000 mm to 1,500 mm.

[0087] After processing was completed, images of the conical tail portion 54a during the loading process and the unloading process were compared to determine whether any of the conical tail portions 54a had broken off and been left behind in the support device 2b. If any were left behind, an alarm sounded and the device automatically stopped. To verify the method (device) of the present invention, an operator checked each individual rod to ensure that no broken conical tail portion 54a had been left behind in the support device 2b. The cylindrical grinding machine used in Example 2 was set up to process crystal rods with diameters of 200 mm, 150 mm, and 125 mm. The length L of the conical tail portion 54a of each crystal rod was randomly selected.

[0088] The results of Example 2 are shown in Table 2.

[0089]

[0090] As can be seen from the results in Tables 1 and 2, according to the embodiment of the present invention, if the conical tail portion 54a is left behind in the bending support device 2b during continuous cylindrical grinding processing, it is confirmed that the device is automatically identified and the device is automatically stopped to prevent quality defects and damage to the device.

[0091] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. A cylindrical grinding method for cylindrically grinding a crystal rod using a cylindrical grinding machine comprising a pair of support units that axially sandwich the crystal rod via a main shaft and a sub-shaft attached to the tip of each support device that supports the end of the crystal rod, allowing it to rotate around the axis, and a grinding unit that cylindrically grinds the outer periphery of the crystal rod while moving along the axial direction of the crystal rod supported by the pair of support units, wherein the support device has a concave support portion that can support the conical end of the crystal rod, and the cylindrical grinding machine is equipped with a remaining state determination means that determines whether a portion of the conical end of the crystal rod remains within the support portion, and wherein, in the continuous cylindrical grinding process, if the remaining state determination means determines that a portion of the end does not remain within the support portion, the continuous process is continued, and if it determines that a portion of the end remains, the continuous process is stopped.

2. The cylindrical grinding method according to claim 1, characterized in that the remaining state determination means makes a determination by acquiring images of the conical end of the crystal rod before and after the cylindrical grinding, comparing the images, and determining that a portion of the conical end of the crystal rod remains within the support portion if it is determined that the conical end of the crystal rod is missing after the cylindrical grinding.

3. The cylindrical grinding method according to claim 1, characterized in that the remaining state determination means determines that a portion of the conical end of the crystal rod remains within the support portion when compressed air is supplied to the space surrounded by a portion of the conical end of the crystal rod and the support portion, and a pressure sensor detects an increase in pressure in the space.

4. A cylindrical grinding method according to any one of claims 1 to 3, characterized in that the continuous processing is stopped automatically.

5. A cylindrical grinding machine comprising a pair of support units, each of which has a support device for supporting the end of a crystal rod, sandwiching the crystal rod in the axial direction via a main shaft and a sub-shaft attached to the tip of the support device, allowing it to rotate around its axis, and a grinding unit that moves along the axial direction of the crystal rod supported by the pair of support units to cylindrically grind the outer periphery of the crystal rod, wherein the support device has a concave support portion that can support the conical end of the crystal rod, and the cylindrical grinding machine is equipped with a remaining state determination means that determines whether a portion of the conical end of the crystal rod remains within the support portion during the continuous cylindrical grinding process, and has the function of emitting a determination signal if it is determined that a portion remains.

6. The cylindrical grinding machine according to claim 5, characterized in that the remaining state determination means has an image capturing unit and a defect determination unit, the image capturing unit has the function of acquiring images of the conical end of the crystal rod before and after the cylindrical grinding, and the defect determination unit has the function of determining that a portion of the conical end of the crystal rod remains within the support unit when it determines by comparing the images that the conical end of the crystal rod is defective after the cylindrical grinding.

7. The cylindrical grinding machine according to claim 5, characterized in that the remaining state determining means has a compressed air supply unit and a pressure sensor, the compressed air supply unit having the function of supplying compressed air into the support unit, and the pressure sensor having the function of detecting an increase in pressure within the support unit and, when an increase in pressure is detected, determining that a portion of the conical end of the crystal rod remains within the support unit.

8. The cylindrical grinding machine according to any one of claims 5 to 7, characterized in that it is equipped with an automatic stopping means having the function of automatically stopping the continuous processing when the remaining state determining means determines that a part of the conical end of the crystal rod remains within the support portion.

Images