Bandsaw cutting machine

Abstract

This invention provides a band saw cutting machine that automatically adjusts the tension of the band saw, thereby improving the cutting accuracy of silicon ingots. [Solution] The band saw cutting machine 100 includes a drive-side and driven-side pulley shafts 122, 124, a moving mechanism 113 that moves pulleys 126, 128 attached to the pulley shafts in the cutting direction, a band saw 104 stretched between the pulleys to cut the silicon ingot 102, a cylinder 132 that biases the driven-side pulley shaft to apply tension to the band saw, servo motors 144, 146 that adjust the inclination angle of the pulley shafts, sensors 134, 136 fixedly positioned close to the pulleys to measure the distance to the surface of the band saw, and a control unit 148 that continuously measures the distance to the surface of the band saw with the sensors while the band saw is moving, calculates the inclination angle of the band saw, and drives the servo motor to adjust the inclination angle of the pulley shaft according to the inclination angle.

Description

Technical Field

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[0001] The present invention relates to a band saw cutting machine for cutting a silicon ingot.

Background Art

[0002] A silicon ingot is a columnar material that serves as a raw material for semiconductor elements, and wafers are manufactured by cutting it to a predetermined thickness using a cutting tool (cutting blade) such as a band saw. In order to make the cutting surface flat, it is important to apply appropriate tension to the blade portion located at the lower edge of the band saw.

[0003] The band saw is wound around a pair of pulleys and runs between the pair of pulleys. When appropriate tension is applied to the blade portion of the band saw, the band saw is firmly stretched between the pair of pulleys, and the tension of the band saw is kept uniform. As a result, vibration during the running of the band saw is suppressed, and the processing accuracy of cutting the silicon ingot is improved.

[0004] <00​​​​​​​​​​​​​​​​​​​​​​​The tension of a band saw is generally adjusted by manually adjusting the position of the pulley shaft. However, when the tension of a band saw is adjusted manually, the tension can be insufficient or excessive depending on the operator's skill, resulting in variations in the cutting accuracy of silicon ingots.

[0007] Furthermore, repeated cutting of silicon ingots can cause the rubber on the pulley that the band saw contacts to deteriorate, leading to a tilt of the band saw and resulting in lower cutting accuracy.

[0008] The electroplated band saw described in Patent Document 1 merely increases the tension of the blade by providing a recess, and does not take any measures to address the decrease in cutting accuracy due to the tilt of the band saw.

[0009] The present invention aims to provide a band saw cutting machine that can automatically adjust the tension of the band saw and improve the cutting accuracy of silicon ingots. [Means for solving the problem]

[0010] To solve the above problems, a typical configuration of the band saw cutting machine according to the present invention is a band saw cutting machine for cutting silicon ingots, comprising: a drive-side pulley shaft and a driven-side pulley shaft; pulleys attached to the pulley shafts and located on both sides of the silicon ingot; a movement mechanism for moving the pulleys in the cutting direction; a band saw stretched between the pulleys and cutting the silicon ingot as the pulleys move; a cylinder that biases the driven-side pulley shaft to apply tension to the band saw; servo motors for adjusting the inclination angles of the pulley shafts; a sensor fixedly positioned close to the pulleys and measuring the distance to the surface of the band saw stretched on the pulleys; and a control unit for controlling the operation of the band saw cutting machine. The control unit continuously measures the distance to the surface of the band saw using the sensor while the band saw is moving, calculates the inclination angle of the band saw, and drives the servo motors to adjust the inclination angle of the pulley shafts according to the calculated inclination angle of the band saw.

[0011] Preferably, the control unit includes a storage unit that stores the tilt angle of the pulley shaft when the wafer cut from the silicon ingot by the band saw is a good product as angle data for good products, and the control unit drives the servo motor to adjust the tilt angle of the pulley shaft according to the angle data for good products read from the storage unit whenever the band saw or pulley is replaced or whenever the silicon ingot is cut. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a band saw cutting machine that can automatically adjust the tension of the band saw and improve the cutting accuracy of silicon ingots. [Brief explanation of the drawing]

[0013] [Figure 1] This diagram shows the configuration of a band saw cutting machine in an embodiment of the present invention. [Figure 2] This diagram illustrates the mechanism for adjusting the tilt angle of the pulley shaft of the band saw cutting machine shown in Figure 1. [Figure 3] This figure shows the method for calculating the inclination angle of the band saw of the band saw cutting machine shown in Figure 1. [Figure 4] Figure 1 is a flowchart showing the operation when replacing the band saw blade in the band saw cutting machine. [Figure 5] Figure 1 is a flowchart showing the operation of the band saw cutting machine during the cutting process. [Modes for carrying out the invention]

[0014] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific numerical values ​​shown in these embodiments are merely examples to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustrations.

[0015] Figure 1 shows the configuration of a band saw cutting machine 100 in an embodiment of the present invention. The band saw cutting machine 100 is a device for cutting a silicon ingot 102 and includes a band saw 104 which is a cutting tool (cutting blade).

[0016] The silicon ingot 102 is a cylindrical material that serves as the base for semiconductor devices. Wafers are manufactured by cutting the silicon ingot 102 to a predetermined thickness using a band saw 104. If the cutting accuracy of the band saw 104 is high, the cut surface of the silicon ingot 102 will be flat, resulting in the production of high-quality wafers. To make the cut surface of the silicon ingot 102 flat, it is important to apply appropriate tension to the band saw 104.

[0017] Therefore, the band saw cutting machine 100 employs a configuration that allows for the continuous maintenance of proper straightness of the band saw 104 during the cutting of the silicon ingot 102, and also allows for the automatic and optimal adjustment of the tension of the band saw 104. This will be explained in detail below.

[0018] The band saw cutting machine 100 comprises a base 106 installed on the floor of a factory or the like, two rails 108, and a table 110. The rails 108 are fixed to the upper surface of the base 106 and extend horizontally, arranged parallel to each other. The table 110 is guided to move horizontally relative to the base 106 by the rails 108. A silicon ingot 102 is placed on the table 110.

[0019] The band saw cutting machine 100 also includes a column 112 attached to the base 106 and a moving mechanism 113 for moving the band saw 104 up and down. By driving the base drive motor 118, the moving mechanism 113 can move the base 116 to which the pulley shafts 122 and 124 are attached in the vertical direction with respect to the column 112.

[0020] The moving mechanism 113 has two rails 114, a base 116, and a base drive motor 118. The rails 114 are fixed to the front surface of the column 112, extend in the vertical direction, and are arranged parallel to each other. The base 116 is movably assembled to the rails 114. Therefore, the base 116 is guided by the rails 114 to be movable in the vertical direction with respect to the column 112.

[0021] The base drive motor 118 is fixed to the upper surface of the column 112. The base drive motor 118 is located between the two rails 114 and further rotates the shaft 120. When the shaft 120 rotates, the base 116 moves in the vertical direction.

[0022] On the base 116, a driving pulley shaft 122 and a driven pulley shaft 124 are attached so as to be separated in the left - right direction. A pulley 126 is attached to the lower end side of the driving pulley shaft 122 which is a driving shaft. A pulley 128 is attached to the lower end side of the driven pulley shaft 124 which is a driven shaft.

[0023] The pulleys 126 and 128 are located on both sides of the silicon ingot 102 in the left - right direction. Also, a band saw 104 is mounted between the pulleys 126 and 128. The band saw 104 is wound around and tensioned by the pulleys 126 and 128 and abuts against the rubbers 126a and 128a located at the edges of the pulleys 126 and 128. When the base 116 moves in the vertical direction, the pulleys 126 and 128 move in the cutting direction (vertical direction) for cutting the silicon ingot 102 with the band saw 104.

[0024] The band saw cutting machine 100 also includes a belt drive motor 130, a hydraulic cylinder 132, and two sensors 134 and 136. The belt drive motor 130 is installed on the upper end of the pulley shaft 122 and rotates the shaft 138. When the shaft 138 rotates, the drive-side pulley shaft 122 and pulley 126 rotate, and power is transmitted to the pulley 128 via the band saw 104. As a result, the driven-side pulley shaft 124 and pulley 128 rotate, and the band saw 104 travels between the pulleys 126 and 128.

[0025] The hydraulic cylinder 132 is mounted on the base 116 and biases the driven pulley shaft 124 to apply tension (basic tension) to the band saw 104. Sensors 134 and 136 are distance sensors that measure the distance to the surface of the band saw 104 stretched on the pulleys 126 and 128. Sensors 134 and 136 are supported by support members 140 and 142 that are attached to the side of the base 106 and extend vertically. This ensures that sensors 134 and 136 are fixedly positioned in close proximity to the pulleys 126 and 128.

[0026] Furthermore, the band saw cutting machine 100 includes two servo motors 144 and 146 and a control unit 148. The control unit 148 controls the operation of the band saw cutting machine 100. The servo motors 144 and 146 adjust the tilt angles of the pulley shafts 122 and 124 respectively through numerical control by the control unit 148 (see Figure 2).

[0027] The control unit 148 has a storage unit 150 that stores angle data for good products. The angle data for good products refers to the inclination angles of the pulley shafts 122 and 124 when the wafer cut from the silicon ingot 102 by the band saw 104 is a good product.

[0028] Figure 2 illustrates the mechanism for adjusting the tilt angles of the pulley shafts 122 and 124 of the band saw cutting machine 100 shown in Figure 1. Note that the band saw 104 is omitted in the figure.

[0029] The servo motors 144 and 146 are mounted on the base 116 and rotate the shafts 144a and 146a, respectively. As the shafts 144a and 146a rotate, the pulley shafts 122 and 124 tilt around the angle adjustment central shafts 152 and 154, respectively.

[0030] In this way, the band saw cutting machine 100 allows the tilt angles of the pulley shafts 122 and 124 to be adjusted by driving the servo motors 144 and 146, respectively. Also, since the pulleys 126 and 128 are attached to the pulley shafts 122 and 124, they tilt according to the tilt angles of the pulley shafts 122 and 124, as shown by arrows A and B in the figure.

[0031] Figure 3 shows a method for calculating the inclination angle of the band saw 104 of the band saw cutting machine 100 shown in Figure 1. Figure 3(a) shows the state before cutting the silicon ingot 102, with the band saw 104 positioned above the silicon ingot 102. Figure 3(b) shows the state in which the pulleys 126 and 128 are moved downward by the moving mechanism 113 (see Figure 1), and the silicon ingot 102 is being cut by the band saw 104.

[0032] As described above, sensors 134 and 136 are fixedly positioned in close proximity to pulleys 126 and 128. Therefore, even if pulleys 126 and 128 are moved by the moving mechanism 113, sensors 134 and 136 do not move. On the other hand, when pulleys 126 and 128 are moved by the moving mechanism 113 from the state shown in Figure 3(a) to the state shown in Figure 3(b), the band saw 104 moves in the cutting direction (up and down direction).

[0033] Therefore, the control unit 148 shown in Figure 1 continuously measures the distance to the surface of the band saw 104 using distance measuring sensors 134 and 136 while the band saw 104 is moving. Based on this, the control unit 148 can calculate the inclination angle of the band saw 104 based on the distance to the surface of the band saw 104 and the angle.

[0034] Figure 4 is a flowchart showing the operation of replacing the band saw 104 using the band saw cutting machine 100 shown in Figure 1. The lower edge of the band saw 104 has a blade portion formed by fixing hard abrasive grains, for example. The blade portion of the band saw 104 deteriorates with repeated cutting of silicon ingots 102, which may reduce the cutting accuracy. Therefore, the band saw cutting machine 100 replaces the band saw 104 periodically.

[0035] First, in the band saw cutting machine 100, when replacing the band saw 104, the operator wraps the new band saw 104 around the pulleys 126 and 128 and installs the band saw 104 between the pulleys 126 and 128 (step S100). Next, the control unit 148 controls the hydraulic cylinder 132 to bias the driven pulley shaft 124 and apply tension to the band saw 104 (step S102).

[0036] Next, the control unit 148 drives the base drive motor 118 of the moving mechanism 113 to move the pulleys 126 and 128 in the cutting direction (step S104). Furthermore, the control unit 148 continuously measures the distance to the surface of the band saw 104 using sensors 134 and 136 (step S106) and calculates the inclination angle of the band saw 104 (step S108).

[0037] Then, the control unit 148 drives the servo motors 144 and 146 to adjust the tilt angles of the pulley shafts 122 and 124 according to the calculated tilt angle of the band saw 104 (step S110).

[0038] Therefore, according to the band saw cutting machine 100, even after replacing the band saw 104, the straightness of the new band saw 104 stretched between the pulleys 126 and 128 can be properly maintained, and the tension of the band saw 104 can be automatically and optimally adjusted.

[0039] Furthermore, repeated cutting of the silicon ingot 102 may cause the rubber 126a and 128a of the pulleys 126 and 128 that the band saw 104 contacts to deteriorate, potentially causing the band saw 104 to tilt and reducing cutting accuracy. Therefore, in the band saw cutting machine 100, instead of replacing the band saw 104 in step S100, the pulleys 126 and 128 may be replaced, and the subsequent processing may be carried out.

[0040] In this way, the band saw cutting machine 100 can maintain the proper straightness of the band saw 104 even after replacing the pulleys 126 and 128, and can automatically adjust the tension of the band saw 104 to the optimal level.

[0041] Figure 5 is a flowchart showing the operation of the band saw cutting machine 100 in Figure 1 during the cutting process. First, in the band saw cutting machine 100, the control unit 148 continuously measures the distance to the surface of the band saw 104 using sensors 134 and 136 while the silicon ingot 102 is being cut by the band saw 104 (step S200).

[0042] Next, the control unit 148 calculates the inclination angle of the band saw 104 based on the distance and angle to the surface of the band saw 104 (step S202). The control unit 148 also drives the servo motors 144 and 146 to adjust the inclination angles of the pulley shafts 122 and 124 according to the calculated inclination angle of the band saw 104 (step S204).

[0043] Next, the control unit 148 reads the angle data for good wafers from the storage unit 150 (see Figure 1). The control unit 148 then determines whether the tilt angles of the pulley shafts 122 and 124 adjusted in step S204 match the angle data for good wafers (the tilt angles of the pulley shafts 122 and 124 for good wafers) (step S206).

[0044] If the two do not match in step S206 (No), the control unit 148 adjusts and optimizes the adjustment values ​​of the servo motors 144 and 146 so that the tilt angles of the pulley shafts 122 and 124 match the angle data for good products (step S208).

[0045] Furthermore, if both conditions are met in step S206 (Yes), or if both conditions are met in step S208, the control unit 148 determines whether or not the cutting of the silicon ingot 102 by the band saw 104 has been completed (step S210).

[0046] If the cutting of the silicon ingot 102 is not completed in step S210 (No), the control unit 148 returns to step S200 and continues cutting the silicon ingot 102. If the cutting is completed (Yes), the control unit 148 terminates the processing associated with the cutting.

[0047] Therefore, with the band saw cutting machine 100, during the cutting process of cutting the silicon ingot 102 with the band saw 104, the straightness of the band saw 104 can be continuously maintained at an appropriate level, and the tension of the band saw 104 can be automatically and optimally adjusted. As a result, even if the inclination angle of the band saw 104 gradually changes with respect to the inclination angle of the pulley shafts 122 and 124, the straightness of the band saw 104 can always be maintained. Consequently, the movement of the band saw 104 between the pulleys 126 and 128 is stable, and the cutting accuracy of the silicon ingot 102 can be improved. In addition, since the tension of the band saw 104 is automatically adjusted, work efficiency can be increased.

[0048] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. [Industrial applicability]

[0049] This invention can be used as a band saw cutting machine for cutting silicon ingots. [Explanation of Symbols]

[0050] 100…Band saw cutting machine, 102…Silicon ingot, 104…Band saw, 106…Base, 108, 114…Rail, 110…Table, 112…Column, 113…Moving mechanism, 116…Base, 118…Motor for base drive, 120, 138, 144a, 146a…Shaft, 122, 124…Pulley shaft, 126, 128…Pulley, 126a, 128a…Pulley rubber, 130…Motor for belt drive, 132…Hydraulic cylinder, 134, 136…Sensor, 140, 142…Support member, 144, 146…Servo motor, 148…Control unit, 150…Memory unit, 152, 154…Angle adjustment center axis

Claims

1. In a band saw cutting machine for cutting silicon ingots, The drive side and the driven side pulley shafts, The pulleys are attached to the aforementioned pulley shaft and are located on both sides of the silicon ingot, A moving mechanism for moving the pulley in the cutting direction, A band saw stretched between the pulleys, which cuts the silicon ingot as the pulleys move, A cylinder that biases the driven pulley shaft to apply tension to the band saw, A servo motor for adjusting the tilt angle of each of the pulley shafts, A sensor is fixedly positioned in close proximity to the pulley and measures the distance to the surface of the band saw stretched across the pulley, The band saw cutting machine comprises a control unit that controls the operation of the band saw cutting machine, The control unit, While the band saw is moving, the distance to the surface of the band saw is continuously measured by the sensor to calculate the inclination angle of the band saw. A band saw cutting machine characterized by driving the servo motor to adjust the tilt angle of the pulley shaft according to the calculated tilt angle of the band saw.

2. The system includes a storage unit that stores the tilt angle of the pulley shaft when the wafer cut from the silicon ingot by the band saw is a good product, as angle data for good products. The band saw cutting machine according to claim 1, characterized in that the control unit drives the servo motor to adjust the inclination angle of the pulley shaft according to the angle data for a good product read from the storage unit each time the band saw or the pulley is replaced or the silicon ingot is cut.

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