JP6180901B2 - Grinding equipment - Google Patents

Description

  The present invention relates to a grinding apparatus for grinding a plate-like workpiece.

  In a grinding apparatus for grinding a plate-like workpiece, grinding is performed while measuring the height of the surface to be ground of the plate-like workpiece in order to obtain a desired thickness of the ground plate-like workpiece (for example, (See Patent Document 1 and Patent Document 2). As a measuring instrument (height gauge) that measures the height of the surface to be ground of a plate-like workpiece, a measuring element (feeler) connected to the end of a swingable arm is brought into contact with the object to be measured, and the position of the arm is read. A contact-type sensor (for example, see Patent Document 3) that converts an electrical signal with a (transducer) is used.

  Further, during grinding, foreign matter such as grinding dust may adhere to the tip of the probe. In particular, when the plate-like workpiece is a hard workpiece such as sapphire, silicon carbide (SiC), gallium nitride (GaN), when grinding scrap enters between the measuring element and the surface to be ground of the plate-like workpiece, The surface to be ground may be scratched, or the tip of the probe may be damaged or worn. If the probe is scratched, accurate measurement cannot be performed. In order to avoid the occurrence of such a problem, Patent Document 2 describes that cleaning water is supplied to the contact portion between the measuring element and the plate-like workpiece to prevent the adhesion of foreign matters.

Japanese Patent Laid-Open No. 61-25769 JP 2005-246491 A Japanese Patent No. 3856842

  However, when measuring the height of the surface to be ground while grinding, a measurement error may occur due to thermal expansion of the probe or the arm due to the influence of processing heat. In order to increase the grinding accuracy, it is necessary to reduce the measurement error. Therefore, for example, it is conceivable to cool the measuring device with cooling water to make the temperature constant, but the temperature of the reading unit rises due to the influence of the temperature in the processing chamber, and the measurement error due to the temperature rise of the reading unit is It can happen.

  The present invention has been considered in view of such problems, and an object of the present invention is to improve the grinding accuracy of a grinding apparatus by reducing an error in measuring the height of a surface to be ground of a plate-like workpiece.

  A grinding apparatus according to the present invention includes a chuck table for holding a plate-like workpiece, a grinding means for grinding the upper surface of the plate-like workpiece held on the chuck table, and the plate-like workpiece ground by the grinding means. A height measuring device for measuring the height of the upper surface, wherein the height measuring device is connected to the measuring member that is brought into contact with at least the upper surface of the plate-like workpiece, and the measuring member. An arm, a support unit that supports the arm, a vertical drive unit that moves the arm up and down with the support unit as a fulcrum, a sensor that reads the position of the arm that moves up and down, the support unit, the vertical drive unit, and the sensor A first case for projecting the arm, a side wall surrounding the height measuring device, a top plate connected to the upper side of the side wall, and a lower side of the side wall A coupled bottom plate 2, the bottom plate is provided with a passage port through which the probe moving up and down by the vertical drive unit is passed, and the top plate is a supply port for supplying cooling water into the second case And when the height measuring device measures the height of the upper surface of the plate-like work held by the chuck table, the cooling water is supplied from the supply port, While keeping the temperature constant, discharging the cooling water from the passage port prevents foreign matter from adhering to the contact portion of the measuring element.

  The second case is provided with a discharge port for discharging the cooling water in the top plate, and by taking in a larger amount of cooling water from the supply port than the amount discharged from the passage port, the second case It is preferable to fill the case with the cooling water and to discharge the overflowing cooling water from the discharge port.

  According to the grinding device of the present invention, the temperature in the second case can be made constant by the cooling water taken in from the supply port, so the temperature of the height measuring device accommodated in the second case is also constant. Thus, measurement in a constant temperature environment is possible, and the height measurement error of the surface to be ground of the plate workpiece can be reduced. Further, since the cooling water is discharged from the passage port to prevent foreign matter from adhering to the contact portion of the probe, it is possible to prevent the contact portion from being damaged and causing a measurement error. Thereby, the grinding precision of a grinding device can be made high. Further, the plate-like workpiece can be prevented from being damaged.

  If more cooling water than the amount discharged from the passage port is taken in from the supply port and the second case is filled with cooling water, the first case will be completely submerged. The grinding accuracy of the grinding device can be further increased.

The partially broken perspective view which shows a grinding device. The side view expanded sectional view which shows a grinding device. The side view expanded sectional view which shows another grinding device.

  A grinding apparatus 10 shown in FIG. 1 includes a chuck table 11 that holds a plate-like workpiece such as a wafer, a grinding unit 12 that grinds the upper surface of the plate-like workpiece held on the chuck table 11, and a grinding unit 12 in ± Z directions. Grinding feed means 13 to be moved to, height measuring device 14a for measuring the height of the upper surface of the plate-like workpiece ground by the grinding means 12, and height measurement for measuring the height of the holding surface 111 of the chuck table 11. 14b, a second case 15 accommodating the two height measuring devices 14a and 14b, and a column 16 for supporting the height measuring devices 14a and 14b and the second case 15. Note that there is no height measuring device 14b for measuring the height of the holding surface 111 of the chuck table 11, and only the height measuring device 14a for measuring the height of the upper surface of the ground plate workpiece is the second case. 15 may be accommodated.

  The chuck table 11 can move in the ± Y directions and can rotate, and can suck and hold the plate-like workpiece placed on the holding surface 111.

  The grinding means 12 can rotate the grinding wheel 20 attached to the mount 122 provided at the end on the −Z side of the spindle 121 by rotating the spindle 121 having an axis in the ± Z direction. A plurality of grinding wheels 21 are fixed to the lower surface of the grinding wheel 20 in an annular shape.

  The grinding feed means 13 can move the moving part 133 engaged with the screw shaft 131 in the ± Z direction according to the guide 134 by the motor 132 rotating the screw shaft 131 parallel to the ± Z direction. The grinding means 12 is fixed to the moving unit 133 and moves in the ± Z direction as the moving unit 133 moves.

  The second case 15 is connected to the fluid supply means 30. The fluid supply means 30 includes a cooling water supply source 31 that supplies cooling water having a constant temperature, and a valve 32 that adjusts the amount of cooling water supplied. It is supplied to the case 15.

  In the grinding apparatus 10, a plate-like workpiece to be ground is held on the chuck table 11, the grinding means 12 rotates the grinding wheel 20, and the grinding feed means 13 moves the grinding means 12 in the −Z direction to move to the chuck table 11. The plate-like workpiece is ground by bringing the grinding wheel 21 fixed on the −Z side surface of the grinding wheel 20 into contact with the + Z-side surface of the plate-like workpiece held by the chuck table 11.

  The grinding device 10 grinds the plate workpiece, and the difference between the height of the upper surface of the plate workpiece measured by the height measuring device 14a and the height of the holding surface 111 of the chuck table 11 measured by the height measuring device 14b. From this, the current thickness of the plate workpiece is calculated, and when the calculated thickness reaches a desired thickness, the grinding is finished. If the height measuring device 14b is not provided, the grinding is finished when the height of the upper surface of the plate-like workpiece measured by the height measuring device 14a reaches a predetermined height.

  As shown in FIG. 2, the height measuring instrument 14 a includes a first case 41 fixed to the support column 16, a support portion 42 accommodated in the first case 41, and a fulcrum 421 provided in the support portion 42. An arm 43 supported by a support portion 42 so as to be able to swing up and down as a center, a measuring element 44 connected to the arm 43, and a sensor 45 for reading the position of the arm 43 housed in the first case 41 and swinging And an up-and-down drive unit 46 which is accommodated in the first case 41 and swings the arm 43 up and down with the support unit 42 as a fulcrum. The structure of the height measuring device 14b shown in FIG. 1 is the same as that of the height measuring device 14a. The two height measuring devices 14a and 14b may each be provided with a first case 41, and one first case 41 may be provided with a support portion 42 and an arm constituting the two height measuring devices 14a and 14b. 43, the sensor 45, and the vertical drive unit 46 may be accommodated.

  The first case 41 is provided with an opening 411 for projecting the arm 43. In order to prevent the cooling water from entering the first case 41, the opening 411 is closed with a packing 412 through which the arm 43 penetrates. The packing 412 is configured to be flexibly deformable so as not to disturb the swinging of the arm 43.

  The arm 43 oscillates in a plane parallel to the XZ plane around a support axis parallel to the ± Y direction. The measuring element 44 is connected to a protruding portion 431 in which the arm 43 protrudes from the first case 41 in a state substantially parallel to the ± Z direction.

  The sensor 45 includes a coil 451 and a core 452 fixed to the arm 43. When the arm 43 swings, the positional relationship between the coil 451 and the core 452 changes, and thereby the inductance of the coil 451 changes. By converting this into an electrical signal, the sensor 45 measures the position of the arm 43. The result measured by the sensor 45 is stored in the storage unit 17. Based on the position of the arm 43 measured by the sensor 45 when the contact portion 441 provided at the −Z side end of the probe 44 is brought into contact with the upper surface 61 of the plate-like workpiece 60, the upper surface 61 of the plate-like workpiece 60 is measured. Is required. The sensor 45 is not limited to an inductive type such as an operating transformer (LVDT), and may measure the position of the arm 43 by, for example, a capacitance type that reads a change in capacitance or other methods. .

  The vertical drive unit 46 includes a cylinder 461 and a piston 462 that is driven by the cylinder 461 and moves in the ± Z direction. When measuring the height of the upper surface 61 of the plate-like workpiece 60, the arm 43 can freely move up and down by moving the piston 462 in the -Z direction. As a result, the contact portion 441 of the probe 44 comes out of the second case 15 and contacts the upper surface 61 of the plate-like workpiece 60. Before the measurement is started or after the measurement is completed, the piston 462 is moved in the + Z direction to lift the arm 43 at the end of the piston 462 on the + Z side, and the contact portion 441 of the measuring element 44 is stored in the second case 15. To do.

  The second case 15 includes a side wall 51 surrounding the two height measuring devices 14 a and 14 b, a top plate 52 connected to the upper side of the side wall 51, and a bottom plate 53 connected to the lower side of the side wall 51. I have.

  The top plate 52 is provided with a supply port 54 for supplying cooling water into the second case 15. The supply port 54 is connected to the valve 32. The valve 32 includes a bidirectional valve 321 that opens and closes and a variable throttle valve 322 for adjusting the amount of cooling water supplied. The supply port 54 may be provided on the side wall 51 instead of the top plate 52.

  The bottom plate 53 is provided with a passage port 531 for passing the contact portion 441 of the measuring element 44 that is driven by the vertical drive unit 46 to move up and down. When the grinding apparatus 10 includes two height measuring devices 14a and 14b, two passage ports 531 may be provided corresponding to the respective measuring elements 44, and one common passage port 531 is provided. You may comprise so that the two measuring elements 44 may pass.

  In the second case 15, a water sprinkling portion 55 for discharging the cooling water uniformly is provided. The water sprinkling part 55 has a hollow plate shape, has an intake 551 connected to the supply port 54 on the surface on the + Z side, and has a large number of water spray holes 552 on the surface on the −Z side. The cooling water supplied through the valve 32 is taken into the water sprinkling part 55 from the intake port 551 and discharged from the water sprinkling hole 552.

  In the second case 15, an overflow pipe 56 for submerging the first case 41 is further provided. The overflow pipe 56 has a tubular shape parallel to the ± Z direction, and the −Z side end is connected to the passage port 531 and the + Z side end is open. The measuring element 44 is disposed inside the overflow pipe 56. A slit 561 is provided on the side surface of the overflow pipe 56 in order to pass the arm 43 connected to the measuring element 44. When the grinding apparatus 10 includes two height measuring devices 14 a and 14 b, two overflow pipes 56 may be provided corresponding to each of the measuring elements 44, or one common overflow pipe 56 may be provided. It is good also as a structure in which the measuring element 44 is accommodated.

  When the plate-like workpiece 60 held on the chuck table 11 is ground using the grinding means 12 shown in FIG. 1, the chuck table 11 is rotated and the rotating grinding wheel 21 is brought into contact with the plate-like workpiece 60. . During such grinding, the height of the upper surface of the plate-like workpiece 60 is measured by the height measuring device 14 a and cooling water is supplied to the second case 15 via the valve 32. The cooling water supplied through the valve 32 is taken into the second case 15 from the supply port 54 and is uniformly sprinkled in the second case 15 by the water sprinkling unit 55. Therefore, the temperature in the second case 15 can be made constant.

  When the sprinkled cooling water is applied to the height measuring devices 14a and 14b, the height measuring devices 14a and 14b are cooled and kept at a constant temperature. The sprayed cooling water stays in the second case 15. When the water level in the second case 15 reaches the slit 561, the cooling water flows into the overflow pipe 56 from the gap between the slit 561 and the arm 43. To rise. When the water level reaches the upper end of the overflow pipe 56, the cooling water flows into the overflow pipe 56, so that the water level does not rise any more and is kept constant. The upper end of the overflow pipe 56 is preferably provided at a position where at least the arm 43 is completely submerged, and is provided at a position where the first case 41 is substantially submerged. By submerging the height measuring devices 14a and 14b, the cooling effect is enhanced, and the height measuring devices 14a and 14b are kept at a constant temperature. Note that, in order to prevent the cooling water from flowing out from the slit 561, it may be configured to be sealed with packing in the same manner as the opening 411.

  Since the protrusion 431 and the measuring element 44 of the arm 43 disposed outside the first case 41 are always submerged, they are directly cooled by the cooling water and kept at a constant temperature.

  On the other hand, since the first case 41 is sealed with the packing 412, the cooling water does not enter the first case 41 even if the first case 41 is submerged. For this reason, problems such as the sensor 45 getting wet and malfunctioning can be prevented.

  The portions disposed in the first case 41 such as the sensor 45 are not cooled directly because they are not exposed to the cooling water, but the first case 41 is submerged, so that the processing heat is the cooling water. As a result, the temperature in the first case 41 becomes constant. For this reason, generation | occurrence | production of the measurement error by the influence of the temperature characteristic etc. of the sensor 45 can be prevented. As described above, since the occurrence of measurement errors in the height measuring devices 14a and 14b can be prevented, the grinding accuracy of the grinding apparatus 10 can be increased.

  The cooling water that has flowed into the overflow pipe 56 is discharged out of the second case 15 through the passage port 531. The cooling water discharged to the outside of the second case 15 creates a radial water flow on the upper surface 61 of the plate-like workpiece 60 toward the outside with the contact portion 441 as the center. Due to this water flow, foreign matter such as grinding scraps cannot approach the measuring element 44, so that foreign matter can be prevented from adhering to the measuring element 44. Even if foreign matter adheres to the probe 44, the probe 44 is always cleaned with cooling water, so that the foreign matter is immediately washed away. Therefore, the contact portion 441 and the upper surface 61 of the plate-like workpiece 60 can be prevented from being damaged. Moreover, since it can prevent that the measurement error by the contact part 441 getting damaged can generate | occur | produce, the grinding precision of the grinding device 10 can be raised. Furthermore, since the cooling water used for cooling the height measuring devices 14a and 14b is used, it is not necessary to supply cleaning water separately. For this reason, while being able to simplify the structure of the grinding apparatus 10, the usage-amount of water can be restrained and cost can be reduced.

  The grinding apparatus 10A shown in FIG. 3 is provided with a point where the overflow pipe 56 is not provided in the second case 15A and a discharge port 521 for discharging cooling water to the top plate 52 of the second case 15. This is different from the grinding apparatus 10 shown in FIG.

  A larger amount of cooling water than the amount of cooling water discharged from the passage port 531 is supplied from the supply port 54 through the valve 32 to the second case 15A of the grinding apparatus 10A. For this reason, even if there is no overflow pipe 56, the water level in the second case 15A rises and the second case 15A is filled with cooling water. The inside of the second case 15A is filled with cooling water, and the cooling water overflows from the discharge port 521.

  Thus, the inside of the second case 15A is completely filled with cooling water, and the height measuring devices 14a and 14b are completely submerged, so that the cooling effect is enhanced. In addition, since the amount of cooling water supplied to the second case 15A is large, the cooling water warmed by cooling the height measuring devices 14a and 14b is discharged more and more, and fresh and cool cooling water is transferred from one to the next. Supplied. Thereby, the cooling effect can be further enhanced.

  Further, since there is no overflow pipe 56, when the grinding is finished and the supply of the cooling water is stopped, the cooling water is discharged out of the second case 15A from the passage port 531. Next, when the grinding is started, since the old and warm cooling water does not stay in the second case 15A, the height measuring devices 14a and 14b can be efficiently cooled, and the cooling effect is enhanced. Can do.

  Since the height measuring devices 14a and 14b are maintained at a constant temperature, it is possible to prevent the measurement error due to the thermal expansion of the arm 43 and the measuring element 44 and the measurement error due to the temperature characteristics of the sensor 45. Thereby, the grinding accuracy of the grinding device 10 can be increased.

  The discharge port 521 may be provided on the side wall 51 instead of the top plate 52, but it is desirable to provide the discharge port 521 at a position as high as possible so that the inside of the second case 15 is filled with cooling water. Further, the entire top plate 52 may be opened to serve as the discharge port 521.

10 grinding device, 11 chuck table, 111 holding surface,
12 grinding means, 121 spindle, 122 mount,
13 grinding feed means,
131 screw shaft, 132 motor, 133 moving part, 134 guide,
14a, 14b Height measuring device,
41 1st case, 411 opening, 412 packing,
42 support part, 421 fulcrum, 43 arm, 431 protrusion,
44 contact point, 441 contact portion, 45 sensor, 451 coil, 452 core,
46 Vertical drive part, 461 cylinder, 462 piston,
15, 15A second case,
51 side wall, 52 top plate, 521 discharge port, 53 bottom plate, 531 passage port,
54 supply port, 55 water sprinkling part, 551 intake port, 552 water sprinkling hole,
56 overflow pipe, 561 slit,
16 struts, 17 storage units,
20 grinding wheel, 21 grinding wheel,
30 Fluid supply means, 31 Cooling water supply source, 32 Valve, 321 Bidirectional valve,
322 variable throttle valve,
60 plate workpiece, 61 top surface

Claims (2)

A chuck table for holding a plate-like workpiece;
Grinding means for grinding the upper surface of the plate-like workpiece held by the chuck table;
A height measuring device for measuring the height of the upper surface of the plate-like workpiece ground by the grinding means;
A grinding apparatus comprising:
The height measuring instrument is
A probe to be brought into contact with at least the upper surface of the plate-like workpiece;
An arm connected to the probe;
A support for supporting the arm;
An up-and-down drive unit that moves the arm up and down with the support unit as a fulcrum;
A sensor that reads the position of the arm that moves up and down;
A first case that houses the support, the vertical drive unit, and the sensor, and that protrudes the arm;
further,
A second case having a side wall surrounding the height measuring device, a top plate connected to the upper side of the side wall, and a bottom plate connected to the lower side of the side wall;
The bottom plate is provided with a passage port through which the measuring element that moves up and down by the vertical driving unit is passed.
The top plate includes a supply port for supplying cooling water into the second case,
When the height measuring instrument measures the height of the upper surface of the plate-like work held by the chuck table, the temperature in the second case is kept constant by receiving cooling water from the supply port. And a grinding device that prevents foreign matter from adhering to the probe by discharging the cooling water from the passage port. The second case includes a discharge port for discharging the cooling water in the top plate,
The second case is filled with the cooling water by taking in a larger amount of cooling water from the supply port than the amount discharged from the passage port, and the overflowing cooling water is discharged from the discharge port. Item 2. The grinding apparatus according to Item 1.

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