JP2005022059A - Grinder and grinding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinder and a grinding method which automatically stabilizes or varies a relative positional relation between a ground object and a grinding tool in real time, and immediately detects abnormal grinding in real time, without trusting engineer's intuition or experience. <P>SOLUTION: The grinder 1 comprises a turn table 10 for holding and rotating a semiconductor wafer (ground object) W and a grinding tool 40 to which a grinding wheel 45 is attached and that rotates and drives. The grinder 1 grinds the ground surface of the semiconductor wafer W into a flat surface by relatively moving the semiconductor wafer W and the grinding tool 40 while the grinding wheel 45 of the grinding tool 40 is pressed onto the semiconductor wafer W held by the turn table 10. Aside from a bearing (air spindle) 49 for pivoting a driving shaft 47 for rotating the grinding tool 40, a magnetic bearing 60 for controlling the attitude of the grinding tool 40 is installed near the grinding tool 40. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface grinder used in a manufacturing process of an object to be ground such as a semiconductor wafer, and in particular, stabilizes or changes a grinding process by stabilizing or changing a relative posture between the object to be ground and a grinding tool. The present invention relates to a grinding machine and a grinding method that can be performed.

  Conventionally, a surface grinding machine (grinding apparatus) has been employed for processing semiconductor wafers. The surface grinder can sharply cut a semiconductor wafer by one grinding, and is effective in reducing the thickness of the semiconductor wafer.

  As shown in FIG. 10, this type of surface grinding machine has a surface of a semiconductor wafer W in which a cup-shaped grinding tool 210 is fixed on a turntable 230 by attaching a plurality of grindstones 211 in a ring shape to the lower surface thereof. At the same time, the grinding tool 210 and the turntable 230 are independently rotated, so that the surface of the semiconductor wafer W is ground flat by the grindstone 211.

  The flatness of the semiconductor wafer W by the grinding process depends on the relative positional relationship (mainly the inclination angle θ) between the semiconductor wafer W and the grinding tool 210. Therefore, conventionally, when satisfactory flatness cannot be obtained by actually grinding the semiconductor wafer W, it has been necessary to finely adjust the tilt angle θ with the intuition and experience of engineers. Therefore, a great amount of time and technology are required for the adjustment.

  Even if the inclination angle θ is adjusted to an optimum value once, vibration generated in the apparatus, vibration from outside, change in outside air temperature, change in temperature in the grinding machine, change in sharpness of the grinding tool 210, semiconductor wafer The flatness changes due to disturbances such as the flatness of W before grinding and the difference in material, but adjustment in real time was impossible with respect to the change in flatness of the ground surface due to this disturbance. Moreover, even if the adjustment is performed after grinding, the adjustment is largely based on the intuition and experience of the engineer as described above, and it is necessary to adjust again every time the flatness changes.

  On the other hand, even when abnormal grinding occurs during grinding, since the occurrence of abnormality cannot be detected until the semiconductor wafer W after grinding is checked, the semiconductor wafer W, the grinding tool 210, the turntable 230, etc. There is a risk of causing damage (for example, so-called burning or damage of the ground surface of the semiconductor wafer W). This abnormal grinding is caused by cutting of grinding water, a change in the state of the grinding tool 210, a change in initial surface roughness or material of the semiconductor wafer W, and the like.

  The present invention has been made in view of the above points, and its purpose is to automatically stabilize the relative positional relationship between an object to be ground and a grinding tool in real time without depending on the intuition and experience of an engineer. It is an object of the present invention to provide a grinding machine and a grinding method that can be changed and that abnormal grinding can be immediately detected in real time.

  The invention according to claim 1 of the present application comprises a turntable that holds and rotates a workpiece and a grinding tool that rotates by driving a grindstone, and grinds the workpiece held on the turntable. In a grinding machine that grinds the grinding surface of the workpiece to a flat surface by moving the workpiece and the grinding tool relative to each other with the tool wheel pressed, the attitude of the grinding tool is controlled by the grinding tool. The grinding machine is characterized in that a magnetic bearing is installed. Since magnetic bearings are installed, the relative posture between the grinding tool and the workpiece can be easily stabilized to the desired posture (positional relationship) during grinding, and the grinding of the workpiece can be stabilized. It can be made. Further, since the relative posture (positional relationship) between the grinding tool and the workpiece can be adjusted using the magnetic bearing, the processing shape of the workpiece can be adjusted quickly and easily. Further, since the non-contact type magnetic bearing is used and the attitude of the grinding tool is controlled, the grinding tool can be smoothly rotated at high speed, and the workpiece can be easily processed by high-speed rotation (≧ 1000 rpm).

  In the invention according to claim 2 of the present application, the grinding machine is preset by the grinding tool using a sensor that detects a relative posture of the grinding tool with respect to an object to be ground, and detection data detected by the sensor. The grinding machine according to claim 1, further comprising a posture control unit that controls the magnetic bearing so as to obtain a posture. Since the relative posture (positional relationship) between the grinding tool and the workpiece can be monitored using a sensor, abnormal grinding can be confirmed in real time, and damage to the workpiece, grinding tool, turntable, etc. during abnormal grinding can be confirmed. Can be minimized. In addition, the relative attitude (positional relationship) between the grinding tool and the workpiece is monitored using a sensor, and the attitude of the grinding tool is controlled by feeding back the monitored results, minimizing the impact on the grinding process due to disturbance. Can be limited.

  The invention according to claim 3 of the present application is characterized in that the sensor is a displacement sensor that detects a displacement of a relative position between a stationary member of the magnetic bearing and a grinding tool at a plurality of locations. It is a grinding machine as described in above.

  In the invention according to claim 4 of the present application, the sensor includes a displacement sensor that detects a displacement of a relative position between a grinding machine body and a grinding tool on which the turntable is installed at a plurality of locations, and between the grinding machine body and the turntable. The grinding machine according to claim 2, further comprising a displacement sensor that detects a displacement of the relative position at a plurality of locations.

  The invention according to claim 5 of the present application is characterized in that the magnetic bearing is installed in the vicinity of the grinding tool separately from a bearing that supports a drive shaft that rotationally drives the grinding tool. The grinding machine according to any one of 1 to 4. This makes it possible to sufficiently control the grinding tool's posture to the desired posture without easily increasing the size of the bearing that supports the drive shaft that rotationally drives the grinding tool, and easily satisfy the requirements for the grinding accuracy of the workpiece. Can do.

  In the invention according to claim 6 of the present application, the surface to be ground of the object to be ground is moved by relatively moving the object to be ground and the grinding tool in a state where the grindstone of the grinding tool is pressed against the object to be ground held on the turntable. In the grinding method for grinding into a flat shape, the relative motion between the object to be ground and the grinding tool is detected by detecting a relative attitude of the grinding tool with respect to the object to be ground, and the detected attitude becomes a preset attitude. Thus, the grinding method is performed while controlling a magnetic bearing that supports the grinding tool.

  The invention according to claim 7 of the present application is characterized in that in a grinding machine comprising a table for holding an object to be ground and a grinding tool that is rotationally driven by attaching a grindstone, a magnetic bearing is installed in the grinding tool. It is a grinder.

  The invention according to claim 8 of the present application is the grinding machine according to claim 7, wherein a hydrostatic bearing is installed on the grinding tool.

  The invention according to claim 9 of the present application is directed to a table for holding an object to be ground, a grinding tool to which a grindstone is attached and rotationally driven, a bearing for pivotally supporting the grinding tool, and a magnetic for controlling tilting of the grinding tool. A grinding machine comprising a bearing.

  The invention according to claim 10 of the present application is the grinding machine according to claim 9, wherein the bearing is a hydrostatic bearing.

According to the present invention, the following effects are produced.
(1) Since the magnetic tool for controlling the attitude of the grinding tool is installed in the grinding tool, the relative attitude between the grinding tool and the workpiece to be ground during grinding is always easily set to the desired attitude (positional relationship). It can be stabilized, and the grinding of the workpiece can be stabilized.

  (2) Since the relative posture (positional relationship) between the grinding tool and the workpiece can be adjusted using the magnetic bearing, the processing shape of the workpiece can be adjusted quickly and easily.

  (3) Since the relative posture (positional relationship) between the grinding tool and the workpiece can be monitored using a sensor, abnormal grinding can be confirmed in real time, and the workpiece, grinding tool, turntable, etc. during abnormal grinding Damage to the can be minimized.

  (4) Since the relative attitude (positional relationship) between the grinding tool and the workpiece is monitored using a sensor, and the attitude of the grinding tool is controlled by feeding back the monitored result, the influence on the grinding process due to disturbances Can be minimized.

  (5) Uses a non-contact type magnetic bearing and controls the attitude of the grinding tool, so that the grinding tool can be smoothly rotated at a high speed, and the workpiece can be easily processed at a high speed (≧ 1000 rpm). .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an overall schematic configuration diagram showing a grinding machine (surface grinding machine) 1 according to an embodiment of the present invention. As shown in the figure, the grinding machine 1 includes a turntable (table) 10 that holds a semiconductor wafer W as an object to be ground on its upper surface, a grinder main body 20 on which the turntable 10 is installed, and a ring-like surface on the lower surface. A grinding tool 40 having a grinding wheel 45 attached thereto, a magnetic bearing (attitude control means) 60 for controlling the attitude of the grinding tool 40, a grinding tool head 80 for holding the grinding tool 40 and the magnetic bearing 60, a displacement sensor 23, An attitude control means 100 for inputting an output signal from the power supply 27, 29 to detect a relative attitude of the grinding tool 40 with respect to the semiconductor wafer W and controlling a relative attitude of the grinding tool 40 with respect to the semiconductor wafer W; 10, a grinding tool head 80, and a drive control means 130 that drives and controls the grinding tool 40. Each component will be described in detail below.

  The turntable 10 is configured by fixing a chuck table 13 made of a porous ceramic plate and a ceramic seal ring 13-1 provided on the outer periphery thereof on a stainless steel base 11. The chuck table 13 is evacuated by a vacuum suction path 17 provided in the drive shaft 15 of the turntable 10, thereby attracting and fixing the entire back surface of the semiconductor wafer W placed on the chuck table 13. Further, a seal ring 13-1 is provided on the outer peripheral portion of the chuck table 13 so that the vacuum does not leak outside. The drive shaft 15 is rotatably supported by a mechanical bearing 18 and is connected to a drive motor (drive means) 21 by a belt 19. When the drive motor 21 is rotationally driven, the turntable 10 and the semiconductor wafer W fixed on the upper surface thereof are rotated. The rotation speed of the turntable 10 is, for example, several rpm to several hundred rpm.

  On the other hand, on the upper part of the grinding machine body 20, a displacement sensor (sensor) 23 for detecting the separation distance between the grinding machine body 20 as a stationary member and the lower surface of the turntable 10 as a rotation member at a plurality of locations. Is installed. As shown in FIG. 2, these displacement sensors 23 are installed at four locations at equal intervals (90 ° intervals) in the circumferential direction with respect to the rotation center of the turntable 10. By measuring the separation distance from each displacement sensor 23 to the lower surface of the turntable 10, how much the surface of the turntable 10 (that is, the surface of the semiconductor wafer W) is inclined from the horizontal position with respect to the grinding machine body 20. Detect whether or not

  Further, a displacement sensor that detects a separation distance between the grinding machine body 20 and the lower surface of the outer circumference of the target base 41 of the grinding tool 40 that is a rotation side member is provided at the tip of the arm 25 that protrudes from the outer circumference of the grinding machine body 20. A (sensor) 27 is installed. In this embodiment, as shown in FIG. 2, three displacement sensors 27 are installed in the circumferential direction with respect to the rotation center of the grinding tool 40, and each displacement sensor 27 is connected to each grinding sensor 40 from each displacement sensor 27. By measuring the separation distance to the lower surface, it is detected how much the surface of the grinding tool 40 (that is, the surface of the grindstone 45) is inclined with respect to the grinding machine body 20 from the horizontal position.

  3A is a schematic cross-sectional view of the main part showing in detail the portions of the grinding tool 40 and the magnetic bearing 60, and FIG. 3B is a view of the grinding tool 40 viewed from the lower surface side (the direction of arrow C in FIG. 3A). FIG. As shown in FIG. 1 and FIG. 1, the grinding tool 40 has a ring-shaped grindstone holder 43 attached to the lower surface of a substantially disc-shaped target base 41, and a large number of plate-shaped grindstones on the lower surface of the grindstone holder 43. A cup-type grinding tool 40 is configured by attaching 45 in a ring shape. Here, the grindstone 45 has a flat plate shape, and the grindstone 45 is attached to the lower surface of a large number of grindstone holders 43 in a ring shape as a whole. The grindstone 45 is a fixed abrasive, and for example, diamond abrasive grains (for example, a particle diameter of 2 to 3 μm) are hardened with a binder made of resin bond or the like. On the other hand, a drive shaft 47 is fixed to the center of the target base 41, and this drive shaft 47 is supported by an air spindle 49. The air spindle 49 is a so-called hydrostatic bearing, and is a shaft support means that reliably supports the drive shaft 47 in a non-contact state and rotatably supported by the air force with the air force. A drive motor (drive means) 53 is connected to the drive shaft 47 protruding from the upper part of the air spindle 49 via a power transmission mechanism 51 as shown in FIG. Although not shown, the grinding tool head 80 is provided with a vertical driving mechanism (for example, a ball screw mechanism) that drives the whole in the vertical direction and a rotational direction driving mechanism that rotates about a vertical axis L1. Yes.

  FIG. 4 is a plan view of the magnetic bearing 60. As shown in FIG. 3 and FIG. 3, the magnetic bearing 60 is a cylindrical radial target 61 fixed to the upper surface of the target base 41 which is a rotation side member, and a fixed side member installed inside the radial target 61. It comprises four electromagnet cores 63a to 63d fixed to a grinding tool head 80 and electromagnetic coils 65a to 65d wound around the electromagnet cores 63a to 63d. The tips of the electromagnet cores 63a to 63d and the inner peripheral surface of the radial target 61 face each other with a predetermined gap. The electromagnet cores 63a to 63d and the radial target 61 are all made of a magnetic material such as permalloy. The electromagnet cores 63a to 63d are formed in a U shape, the electromagnetic coil 65a is disposed on the X axis positive direction side, the electromagnetic coil 65b is disposed on the X axis negative direction side, and the electromagnetic coil 65c is disposed on the Y axis positive direction side. The electromagnetic coil 65d is arranged on the Y axis negative direction side.

  Displacement sensors (sensors) 29 are attached to the lower surfaces of the electromagnet cores 63a to 63d, respectively. Each displacement sensor 29 measures a separation distance between the electromagnet cores 63a to 63d and the upper surface of the target base 41 of the grinding tool 40 located immediately below the magnet cores 63a to 63d. As shown in FIG. 2, four displacement sensors 29 are installed at equal intervals (90 ° intervals) in the circumferential direction with respect to the rotation axis of the grinding tool 40 in this embodiment. By measuring the separation distance from the displacement sensor 29 to the upper surface of the grinding tool 40 (the upper surface of the target base 41), the rotation-side member is used with respect to the electromagnet cores 63a to 63d (that is, the grinding tool head 80) that are stationary members. It is detected how much the surface of a certain grinding tool 40 is inclined from a predetermined position (horizontal position).

  FIG. 6 is a block diagram showing a functional configuration of the attitude control means 100 that controls the magnetic bearing 60. As shown in the figure, the attitude control means 100 includes a subtractor 110 and a controller 111, and the subtractor 110 detects the target value of the attitude of the grinding tool 40 and the coordinates converted by sensors (displacement sensors) 23, 27, and 29. The displacement values α and β of the controlled object (grinding tool 40) converted by the unit 115 are input, and the difference is input to the controller 111 as error signals eα and eβ. Here, α and β respectively indicate the inclination around the X axis and the inclination around the Y axis, as shown in FIG. The X axis and the Y axis are located in the horizontal plane. In this case, the grinding tool 40 has a combined motion of tilting about the X axis and tilting about the Y axis. The error signals eα and eβ are subjected to inclination control and attenuation processing by the PID + local phase advance processing unit 111-1, and further converted into voltage command signals Vα and Vβ through the notch filter 111-2 for vibration removal. The coordinate conversion unit 111-3 converts the control signals Vxu and Vyu for the magnetic bearing 60 into the drive unit 112. The drive unit 112 includes electromagnetic coils 65a to 65d and drive circuits 112-1 and 112-2 that excite them. Each of the signals Vxu and Vyu is supplied to the respective drive circuits 112-1 and 112-2 for displacing the radial target 61 in the positive and negative directions of the X and Y axes shown in FIG. It is converted into exciting currents Ixu +, Ixu−, Iyu +, Iyu−, supplied to the electromagnetic coils 65a to 65d, and controls the posture of the control object (grinding tool 40). That is, when the radial target 61 is displaced in the positive and negative directions of the X and Y axes shown in FIG. 4, the grinding tool 40 can be tilted in any direction with respect to the horizontal plane.

  Returning to FIG. 1, the drive control means 130 includes a drive motor 21 of the grinding machine body 20, a drive motor 53 of the grinding tool head 80, a vertical drive mechanism and a rotational drive mechanism (not shown) of the grinding tool head 80, Various mechanisms for driving the grinding machine 1 such as a vacuum pump (not shown) for vacuum suction of the semiconductor wafer W are controlled.

  Next, a grinding method using the grinding machine 1 will be described. First, the semiconductor wafer W to be ground is fixed on the chuck table 13 of the turntable 10 by vacuum suction. Next, the turntable 10 is rotated by driving the drive motor 21 (for example, several tens of rpm). On the other hand, by driving the drive motor 53, the grinding tool 40 is rotated through the belt 51 (for example, several thousand rpm), and then the grinding tool head 80 is lowered to move the grinding wheel 45 of the grinding tool 40 as shown in FIG. The tip of the semiconductor wafer W is in contact with the surface (surface) W1 of the semiconductor wafer W so that the tip always passes through the center of the semiconductor wafer W, and the surface to be ground W1 of the semiconductor wafer W is ground into a predetermined thickness. To do. During this grinding, grinding water is supplied (not shown). After grinding, the grinding tool head 80 is raised, the drive motors 21 and 53 are stopped, and the grinding tool head 80 is swung horizontally by a swinging means (not shown) and moved from directly above the turntable 10. Then, the semiconductor wafer W on the chuck table 13 is removed. The drive shaft 47 may use a direct drive system in which a drive motor is directly connected without using a belt or the like.

  By the way, since the grinding tool 40 is pressed onto the turntable 10 with a predetermined pressing force during the grinding, the grinding tool 40 may be inclined at a predetermined minute inclination angle θ1-1 with respect to the grinding tool head 80 as shown in FIG. In addition, there is a possibility that the grinding tool head 80 itself tilts by a small tilt angle θ1-2 with respect to the grinder main body 20, and as a sum of these tilt angles θ1-1 and θ1-2, as shown in FIG. There is a possibility that the lower surface (grinding tool 40) of the grindstone 45 is inclined from the horizontal plane by a desired inclination angle θ with respect to the semiconductor wafer W (turntable 10). Therefore, in this embodiment, the grinding tool 40 is horizontal (θ = 0) with respect to the semiconductor wafer W or has an arbitrary inclination angle θ in an arbitrary direction with respect to the horizontal plane (that is, in advance). The posture of the grinding tool 40 is controlled by the magnetic bearing 60 by using the posture control means 100 so that the target value of the posture of the grinding tool 40 is set. Thereby, the grinding tool 40 can grind the semiconductor wafer W in an optimum posture. Specifically, the processing shape of the semiconductor wafer W can be changed by grinding the grinding tool 40 horizontally, or by actively changing the grinding tool 40 to an arbitrary posture. Since the control of the attitude of the grinding tool 40 by the magnetic bearing 60 is continuously performed during grinding, the vibration generated in the apparatus, the vibration from the outside, the atmospheric temperature changing during the grinding, the sharpness of the grinding tool 40, In addition, even if disturbances such as differences in flatness and material before grinding of semiconductor wafers W that are continuously processed occur, the posture of the grinding tool 40 can be automatically adjusted in real time. It is not necessary to rely on intuition and experience, and it is possible to realize appropriate grinding of the semiconductor wafer W very easily.

  Note that not all the displacement sensors 23, 27, and 29 may be used to detect the inclination of the grinding tool 40. That is, for example, since the inclination of the surface of the semiconductor wafer W and the inclination of the surface of the grinding tool 40 can be measured by using the displacement sensor 23 and the displacement sensor 27, the surface of the semiconductor wafer W and the grinding tool can be compared by comparing their outputs. The relative inclination of the surface of the 40 grindstones 45 is obtained. At this time, the displacement sensor 29 is unnecessary. Since the displacement sensor 23 detects the inclination of the turntable 10 at the position closest to the semiconductor wafer W, and the displacement sensor 27 detects the inclination of the grinding tool 40 at the position closest to the grindstone 45, the surface of the semiconductor wafer W is most accurately detected. The relative inclination of the surface of the grindstone 45 of the grinding tool 40 is obtained, which is suitable for realizing proper grinding.

  Further, for example, the grinder main body 20 and the grinding tool head 80 fixed to the grinder main body 20 hardly change from the initial set position even if there is a disturbance, so the surface of the turntable 10, that is, the semiconductor wafer W to be ground. Both the surface W1 and the members on the fixed side of the magnetic bearing 60 fixed to the grinding tool head 80 (specifically, the electromagnet cores 63a to 63d) hold the initial position (horizontal position) with high accuracy. Therefore, by using only the output of the displacement sensor 29 attached to the electromagnet cores 63a to 63d, it is determined how the grinding tool 40 is inclined with respect to the member on the fixed side of the magnetic bearing 60, and this inclined state is obtained as a semiconductor. The magnetic bearing 60 may be controlled by calculating as an inclined state between the surface to be ground W1 of the wafer W and the surface of the grindstone 45 of the grinding tool 40. In this method, only one type of displacement sensor 29 is required (displacement sensors 23 and 27 are unnecessary). Further, the displacement sensor 29 directly measures the displacement between the fixed side members (electromagnet cores 63a to 63d) of the magnetic bearing 60 and the upper surface of the grinding tool 40, so that the inclination of the surface of the grinding tool 40 to be controlled by the present invention is controlled. Since the state is directly measured and controlled, accurate grinding can be realized.

  Of course, if all the three types of displacement sensors 23, 27, 29 are used to measure and control the inclination state of the grinding tool 40 with respect to the semiconductor wafer W, it goes without saying that the grinding can be performed with the highest accuracy.

  In addition, since the distance between the turntable 10 and the grinding tool 40 can be measured by the displacement sensor 27, the grinding amount of the semiconductor wafer W and the amount of wear of the grinding tool can be managed from this measurement data. You can also modify the conditions.

  On the other hand, even when abnormal grinding occurs during grinding, it can be detected immediately in real time and immediately dealt with. That is, for example, the grinding tool 40 pressed against the semiconductor wafer W has a predetermined inclination angle set in advance by grinding water drainage, a change in pressing force by the grinding tool 40, a change in initial surface roughness or material of the semiconductor wafer W, and the like. When the angle of inclination exceeds the predetermined value, the inclination angle is within the set value but cannot be controlled even if it is controlled to the target inclination angle, or the current value of the electromagnetic coils 65a to 65d exceeds a predetermined value. Determines that abnormal grinding has occurred, for example, immediately stops the grinding, and sends an abnormal signal or alarm to inform the abnormality. In other words, in the present invention, it is possible to detect abnormal grinding in real time using a sensor for controlling the magnetic bearing 60. As a result, there is no risk of damaging the semiconductor wafer W, the grinding tool 40, the turntable 10, etc. (for example, so-called burning or damage of the ground surface of the semiconductor wafer W).

  When the magnetic bearing 60 is attached as in the present invention in addition to the air spindle 49 which is a shaft supporting means for supporting the drive shaft 47 as in the grinding machine 1, the following effects are further produced. In other words, the air spindle 49 is strong as a support means for supporting the drive shaft 47. However, when the demand for the grinding accuracy of the semiconductor wafer W is increased, the air spindle 49 alone supports the drive shaft 47 to grind the grinding tool. When trying to obtain a level of 40, not only the air spindle 49 has to be enlarged, but also there is a limit even if it is enlarged. On the other hand, if the magnetic bearing 60 for posture control is separately provided, the requirement for the grinding accuracy of the semiconductor wafer W can be satisfied without increasing the size of the air spindle 49. In this embodiment, the air spindle 49 is used as the support means of the drive shaft 47, but a mechanical bearing or a magnetic bearing may be used instead of the air spindle 49.

  FIG. 8 is an overall schematic configuration diagram showing a grinding machine (surface grinding machine) 1-2 according to another embodiment of the present invention. The grinder 1-2 shown in the figure is different from the grinder 1 shown in FIG. 1 only in the structure for attaching the grinding tool 40 to the drive shaft 47. That is, in this grinding machine 1-2, a gimbal mechanism 90, that is, a bearing ball 91 is interposed in a portion where the grinding tool 40 is attached to the drive shaft 47, and a drive transmission mechanism 94 including a drive flange 92 and a drive pin 93 is provided. Thus, only a mechanism is provided in which the grinding tool 40 is allowed to tilt with respect to the drive shaft 47 and the power is transmitted from the drive shaft 47 to the grinding tool 40 to rotate integrally. If comprised in this way, since the grinding tool 40 can be easily tilted to a predetermined angle with respect to the horizontal surface with respect to the drive shaft 47, the tilting operation of the grinding tool 40 by the magnetic bearing 60 can be performed more smoothly. .

  FIG. 9 is an overall schematic configuration diagram showing a grinding machine (surface grinding machine) 1-3 according to still another embodiment of the present invention. The grinder 1-3 shown in the figure is different from the grinder 1 shown in FIG. 1 in that a magnetic bearing 60-3 for posture control is also installed on the turntable 10 side, whereby the grinding tool 40 and This is the point that both attitude control of the turntable 10 is performed by the magnetic bearings 60 and 60-3. The magnetic bearing 60-3 has the same structure as that of the magnetic bearing 60 attached to the grinding tool 40. The magnetic bearing 60-3 will be described with reference to FIGS. A cylindrical radial target 61-3 fixed to the lower surface of the magnet, and four electromagnet cores 63-3a to 63-3d installed inside the radial target 61-3 and fixed to the grinding machine body 20 which is a fixed member. And electromagnetic coils 65-3a to 65-3d wound around the electromagnet cores 63-3a to 63d. The tips of the electromagnet cores 63-3a to 6-3d and the inner peripheral surface of the radial target 61-3 face each other with a predetermined gap. Each of the electromagnet cores 63-3a to 63d and the radial target 61-3 is made of a magnetic material such as permalloy. The electromagnet cores 63-3a to 63-3d are formed in a U shape, the electromagnetic coil 65-3a is disposed on the X axis positive direction side, the electromagnetic coil 65-3b is disposed on the X axis negative direction side, and the electromagnetic coil 65 is disposed. −3c is arranged on the Y axis positive direction side, and the electromagnetic coil 65-3d is arranged on the Y axis negative direction side.

  A displacement sensor (sensor) 23-3 is attached to the upper surface of each electromagnet core 63-3a-d. Each displacement sensor 23-3 measures a separation distance between the electromagnet cores 63-3a to 63-3d and the lower surface of the turntable 10 located immediately above the electromagnet cores 63-3a to 63-3d. In this embodiment, four displacement sensors 23-3 are installed at equal intervals (90 ° intervals) in the circumferential direction with respect to the rotation center of the turntable 10, as with the displacement sensor 23 shown in FIG. Each displacement sensor 23-3 measures the separation distance from each displacement sensor 23-3 to the lower surface of the turntable 10, so that the electromagnet cores 63-3a to 6d (that is, the grinding machine body 20) which are fixed members are used. On the other hand, it detects how much the surface of the turntable 10 which is a rotation side member is inclined from a predetermined position (horizontal position). The displacement sensor 23-3 can be used for controlling the magnetic bearing 60 by using it as the displacement sensor 23 shown in FIG.

  And also in this magnetic bearing 60-3, the attitude | position of a control target object (turntable 10) is controlled by performing control similar to the attitude | position control means 100 shown in the said FIG. That is, the attitude control means 100 obtains an excitation current for displacing the radial target 61-3 in the positive and negative directions of the X and Y axes shown in FIG. 4 so that the turntable 10 assumes a preset attitude as a target value. These exciting currents are supplied to the respective electromagnetic coils 65-3a to 65d to control the posture of the object to be controlled (turntable 10) and tilt the turntable 10 in an arbitrary direction with respect to the horizontal plane.

  Since the grinding machine 1-3 according to this embodiment controls the attitude of the polishing tool 40 and also independently controls the attitude of the turntable 10, the grinding tool 40 is further optimized for the semiconductor wafer W. Grinding can be performed in a posture, and even if a disturbance occurs during grinding, the posture of the turntable 10 and the grinding tool 40 can be automatically adjusted in real time. Therefore, it is not necessary to rely on the intuition and experience of an engineer as in the prior art, and proper grinding of the semiconductor wafer W can be realized very easily.

  On the other hand, even when abnormal grinding occurs on the turntable 10 side during grinding, this can be detected immediately in real time and can be dealt with immediately. That is, for example, a predetermined inclination angle that is set in advance by the turntable 10 to which the grinding tool 40 is pressed due to cutting of grinding water, a change in pressing force by the grinding tool 40, a change in initial surface roughness or material of the semiconductor wafer W, and the like. If the inclination angle is within the set value but cannot be controlled even if it is controlled to the target inclination angle, it is determined that abnormal grinding has occurred in the turntable 10, for example, immediately While grinding is stopped, an abnormality signal and alarm are issued to notify the abnormality. That is, in the present invention, it is possible to detect abnormal grinding in real time using a sensor for controlling the magnetic bearing 60-3, which causes a large damage to the semiconductor wafer W, the turntable 10, the grinding tool 40, etc. (for example, There is no risk of so-called burning or damage of the ground surface of the semiconductor wafer W.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims and the technical idea described in the specification and drawings. Deformation is possible. Note that any shape, structure, or material not directly described in the specification and drawings is within the scope of the technical idea of the present invention as long as the effects and advantages of the present invention are exhibited. For example, it goes without saying that various modifications can be made to the shape, structure and material of the grindstone 45, for example. The object to be ground by the grinding machine according to the present invention is not limited to the semiconductor wafer W, but also grinding of various other objects to be ground, such as back grinding of device wafers, surface grinding of glass substrates, surface grinding of general machine parts. You may use for. In the above embodiment, the semiconductor wafer W is sucked and fixed to the chuck table 13 of the turntable 10 by vacuum suction. However, the fixing of the workpiece such as the semiconductor wafer W to the turntable 10 is not limited to the above fixing method. It may be fixed using other various methods. The sensors 23, 27, and 29 do not necessarily have to be installed at the above-described positions. In short, the sensors 23, 27, and 29 may be installed anywhere as long as the position of the grinding tool relative to the workpiece can be detected.

1 is an overall schematic configuration diagram showing a grinding machine (surface grinding machine) 1 according to an embodiment of the present invention. It is a figure which shows the installation position of the displacement sensors 23, 27, and 29 with respect to the turntable 10 and the grinding tool 40. FIG. 3A is a schematic cross-sectional view of the main part showing the grinding tool 40 and the magnetic bearing 60 in detail, and FIG. 3B is a partial back view of the grinding tool 40 viewed from the lower surface side. It is a top view of the magnetic bearing 60 (60-3). It is explanatory drawing of the relationship between the inclination (alpha) around the X-axis of the grinding tool 40, and the inclination (beta) around the Y-axis. 3 is a block diagram showing a functional configuration of posture control means 100 for controlling a magnetic bearing 60. FIG. It is a figure which shows the inclination state of the grinding tool. It is a whole schematic block diagram which shows the grinder (surface grinder) 1-2 concerning embodiment of this invention. It is a whole schematic block diagram which shows the grinding machine (surface grinding machine) 1-3 concerning embodiment of this invention. It is a figure which shows the conventional surface grinder.

Explanation of symbols

1 Grinding machine (Surface grinding machine)
W Semiconductor wafer (object to be ground)
10 Turntable (table)
DESCRIPTION OF SYMBOLS 11 Base 13 Chuck table 15 Drive shaft 17 Vacuum suction path 18 Bearing 19 Belt 20 Grinding machine main body 21 Drive motor (drive means)
25 Arm 23, 27, 29 Displacement sensor 40 Grinding tool 41 Target base 43 Grinding wheel holder 45 Grinding wheel 47 Drive shaft 49 Air spindle (hydrostatic bearing, bearing)
51 Power transmission mechanism 53 Drive motor (drive means)
60 Magnetic bearing (attitude control means)
61 Radial target 63a-d Electromagnet core 65a-d Electromagnetic coil 80 Grinding tool head 100 Attitude control means 110 Subtractor 111 Controller 112 Drive part 115 Coordinate conversion part 130 Drive control means 1-2 Grinding machine (Surface grinding machine)
90 Gimbal Mechanism 91 Bearing Ball 1-3 Grinding Machine (Surface Grinding Machine)
60-3 Magnetic bearing 61-3 Radial target 63-3a to d Electromagnet core 65-3a to d Electromagnetic coil 23-3 Displacement sensor (sensor)

Claims (10)

A turntable that holds and rotates a workpiece and a grinding tool that is rotated by attaching a grindstone, and the workpiece to be ground in a state where the grindstone of the grinding tool is pressed against the workpiece held on the turntable. In a grinding machine that grinds the grinding surface of the workpiece to a flat shape by moving the grinding tool and the grinding tool relative to each other,
A grinding machine, wherein a magnetic bearing for controlling a posture of the grinding tool is installed on the grinding tool.   The grinding machine controls the magnetic bearing so that the grinding tool assumes a preset posture by using a sensor that detects a relative posture of the grinding tool with respect to an object to be ground and detection data detected by the sensor. The grinding machine according to claim 1, further comprising an attitude control unit that performs the control.   The grinding machine according to claim 2, wherein the sensor is a displacement sensor that detects a displacement of a relative position between a stationary member of the magnetic bearing and a grinding tool at a plurality of locations.   The sensor detects the displacement of the relative position between the grinding machine body and the grinding tool where the turntable is installed at multiple locations, and detects the displacement of the relative position between the grinding machine body and the turntable at multiple locations. The grinding machine according to claim 2, wherein the grinding machine is configured to include a displacement sensor.   The grinding according to any one of claims 1 to 4, wherein the magnetic bearing is installed in the vicinity of the grinding tool separately from a bearing that supports a drive shaft that rotationally drives the grinding tool. Board. In the grinding method of grinding the surface to be ground of the object to be ground in a planar shape by relatively moving the object to be ground and the grinding tool in a state where the grindstone of the grinding tool is pressed against the object to be ground held on the turntable,
The relative motion between the object to be ground and the grinding tool is such that a relative posture of the grinding tool with respect to the object to be ground is detected by a sensor, and the grinding tool is pivotally supported so that the detected posture becomes a preset posture. A grinding method characterized by being performed while controlling a magnetic bearing. A table for holding an object to be ground;
In a grinding machine equipped with a grinding tool attached to a grindstone and driven to rotate,
A grinding machine, wherein a magnetic bearing is installed on the grinding tool.   The grinding machine according to claim 7, wherein a hydrostatic bearing is installed on the grinding tool. A table for holding an object to be ground;
A grinding tool to which a grindstone is attached and driven to rotate;
A bearing that pivotally supports the grinding tool;
And a magnetic bearing that controls tilting of the grinding tool.   The grinding machine according to claim 9, wherein the bearing is a hydrostatic bearing.

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