JP6300653B2 - Grinding method - Google Patents

Description

  The present invention relates to a grinding method for grinding a plate-like object such as a semiconductor wafer.

  In a small and light electronic device typified by a mobile phone, a semiconductor chip including an electronic circuit such as an IC or an LSI has an essential configuration. For example, a semiconductor chip is formed by dividing the surface of a semiconductor wafer made of a material such as silicon by a plurality of division lines called streets, forming an electronic circuit in each region, and then cutting the semiconductor wafer along the streets. Can be manufactured.

  In recent years, for the purpose of reducing the size and weight of semiconductor chips, there are increasing opportunities to process a semiconductor wafer thinly by a method such as grinding. The grinding of the semiconductor wafer is performed by a method called creep feed (for example, see Patent Document 1) in which a chuck table having a holding surface for holding the semiconductor wafer is moved substantially parallel to the holding surface. Sometimes.

  In creep feed, first, the chuck table holding a semiconductor wafer is moved to a position where it does not overlap in plan view with respect to a grinding wheel in which a plurality of grinding wheels are fixed in an annular shape. After that, the lower surface of the grinding wheel is positioned at a position slightly lower than the upper surface of the semiconductor wafer, and the chuck wheel is moved in parallel with the holding surface while rotating the grinding wheel. Can be ground.

JP 2005-28550 A

  By the way, the above-mentioned chuck table moves along the guide rails arranged in parallel with the holding surface. Therefore, if the guide rails swell, the chuck table cannot be moved linearly. For example, if the guide rail has a vertical undulation, the chuck table moves while being displaced up and down.

  When the chuck table is displaced up and down, the workpiece such as a semiconductor wafer is ground while being vertically displaced with respect to the grinding wheel, and the workpiece cannot be ground flat. In particular, when the workpiece is large, the moving distance of the chuck table is also increased, and it becomes difficult to ensure the linearity of the guide rail, so that the flatness of the workpiece tends to be lowered.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a grinding method capable of ensuring the flatness of a workpiece.

  According to the present invention, the plate-like workpiece is held on the holding surface of the chuck table, and the grinding surface of the rotating grinding wheel is applied to the upper surface side of the workpiece held on the holding surface of the chuck table. A grinding method for grinding the upper surface side of a workpiece by moving the chuck table and the grinding wheel in a direction parallel to the holding surface, the grinding surface acting on the workpiece. A height displacement measuring step for measuring in advance the displacement of the height position of the holding surface of the chuck table when the chuck table passes through a position corresponding to the operating position, and a holding for holding the workpiece by the chuck table And the height position of the grinding surface of the grinding wheel is moved up and down in accordance with the displacement of the height position of the holding surface of the chuck table measured by the height displacement measuring step, and the grinding surface Distance to the holding surface Grinding method which comprises and a grinding step of grinding the upper surface of the workpiece while maintaining a predetermined distance is provided.

  The grinding method of the present invention includes a height displacement measuring step for measuring in advance the displacement of the height position of the holding surface of the chuck table, and a displacement of the height position of the holding surface of the chuck table measured in the height displacement measuring step. And a grinding step of grinding the workpiece while moving the grinding wheel up and down, so that even if the holding surface of the chuck table is displaced up and down, the distance between the grinding surface and the holding surface is set to a predetermined distance. The workpiece can be ground while keeping it.

  Thus, in the grinding method of the present invention, the workpiece is ground at a predetermined distance from the holding surface, so that the flatness of the workpiece can be ensured even when the holding surface of the chuck table is displaced up and down.

It is a perspective view which shows the structural example of a grinding apparatus typically. It is a figure which shows the structural example of a grinding device typically. It is a graph which shows the example of the data obtained by a height displacement measurement process. It is a side view which shows a grinding process typically.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The grinding method according to the present embodiment includes a height displacement measuring step (see FIG. 2), a holding step, and a grinding step (see FIG. 4). In the height displacement measuring step, the displacement of the height position of the holding surface of the chuck table is measured.

  In the holding step, the workpiece is held by the chuck table. In the grinding process, the upper surface side of the workpiece is ground while moving the grinding wheel up and down in accordance with the displacement of the height position of the holding surface of the chuck table measured in the height displacement measuring process. Hereinafter, the grinding method according to this embodiment will be described in detail.

  First, a configuration example of a grinding apparatus used in the grinding method according to this embodiment will be described. FIG. 1 is a perspective view schematically illustrating a configuration example of a grinding apparatus, and FIG. 2 is a diagram schematically illustrating a configuration example of a grinding apparatus.

  As shown in FIG. 1, the grinding device 2 includes a horizontal movement mechanism 4. The horizontal movement mechanism 4 includes two horizontal guide rails 6 extending in a substantially horizontal direction (X-axis direction in FIG. 1), and a horizontal movement table 8 is slidably installed on the horizontal guide rail 6. ing.

  A nut portion (not shown) is provided on the back surface side (lower surface side) of the horizontal movement table 8, and a horizontal ball screw 10 parallel to the horizontal guide rail 6 is screwed to the nut portion. A horizontal pulse motor 12 is connected to one end of the horizontal ball screw 10. When the horizontal ball screw 10 is rotated by the horizontal pulse motor 12, the horizontal movement table 8 moves substantially horizontally along the horizontal guide rail 6.

  A support base 14 is provided on the surface side (upper surface side) of the horizontal movement table 8. A rectangular chuck table 16 is disposed on the support base 14 in a plan view. As shown in FIG. 2, the surface of the chuck table 16 is a holding surface 16 a that sucks and holds the rectangular workpiece 11.

  A negative pressure of a suction source (not shown) acts on the holding surface 16a through a flow path (not shown) formed inside the chuck table 16 to generate a suction force for sucking the workpiece 11. The workpiece 11 is, for example, a plate-like object (wafer) formed of a semiconductor material such as silicon, and has a rectangular upper surface 11a (see FIG. 4) and a lower surface 11b.

  As shown in FIG. 1, a columnar support structure 18 is erected at a position adjacent to the horizontal movement mechanism 4. An elevating mechanism 20 is provided on the front surface of the support structure 18. The elevating mechanism 20 includes two elevating guide rails 22 extending in the vertical direction (Z-axis direction), and an elevating table 24 is slidably installed on the elevating guide rails 22.

  A nut portion (not shown) is fixed to the rear surface side (back surface side) of the lifting table 24, and a lifting ball screw 26 parallel to the lifting guide rail 22 is screwed to the nut portion. A lifting pulse motor 28 is connected to one end of the lifting ball screw 26. By rotating the lifting ball screw 26 by the lifting pulse motor 28, the lifting table 24 moves up and down along the lifting guide rail 22.

  A predetermined fixture 30 is provided on the front surface (front surface) of the lifting table 24. A grinding mechanism 32 that grinds the workpiece 11 is attached to the fixture 30. The grinding mechanism 32 includes a spindle housing 34 fixed to the fixture 30. A spindle 36 that constitutes a rotation shaft is supported on the spindle housing 34.

  As shown in FIG. 2, the spindle housing 34 is fixed to the fixture 30 such that the spindle 36 is slightly inclined with respect to the vertical direction. The inclination angle of the spindle housing 34 can be adjusted by the fixture 30.

  A disc-shaped wheel mount 38 is fixed to the lower end portion (tip portion) of the spindle 36, and a grinding wheel 40 having substantially the same diameter as the wheel mount 38 is attached to the lower surface of the wheel mount 38. As shown in FIG. 2, the grinding wheel 40 includes an annular wheel base 40a made of a metal material such as stainless steel.

  A plurality of grinding wheels 40b are fixed to the lower surface of the wheel base 40a over the entire circumference. In the creep feed used in the grinding method of the present embodiment, a part of the lower surface of the grinding wheel 40b (which may include a part of the side surface) becomes a ground surface that contacts the workpiece 11.

  A rotary drive source (not shown) such as a motor is connected to the upper end side of the spindle 36, and the grinding wheel 40 rotates with a rotational force transmitted from the rotary drive source. A control unit 42 for controlling the height position of the grinding wheel 40 (grinding wheel 40b) is connected to the grinding mechanism 32.

  The control unit 42 includes a CPU 42a that executes various processes and a memory 42b that stores various data. Connected to the control unit 42 is an optical displacement meter 44 for measuring the displacement of the height position of the holding surface 16 a of the chuck table 16.

  The displacement meter 44 is positioned, for example, above the position (working position) where the workpiece 11 held by the chuck table 16 and the grinding surface of the grinding wheel 40b come into contact with each other, and the height of the holding surface 16a is not set. It can be detected by contact. However, when grinding the workpiece 11, the displacement meter 44 is moved to a position where it does not interfere with the grinding wheel 40.

  Next, a grinding method using this grinding apparatus 2 will be described. In the grinding method of the present embodiment, first, a height displacement measuring step for measuring the displacement of the height position of the holding surface 16a of the chuck table 16 is performed.

  Specifically, as shown in FIG. 2, the height position of the holding surface 16 a is detected by the displacement meter 44 while the chuck table 16 is moved in a direction substantially parallel to the holding surface 16 a by the horizontal movement mechanism 4. Thereby, the change (displacement) of the height position of the holding surface 16a when the chuck table 16 passes the position corresponding to the operation position can be detected.

  FIG. 3 is a graph showing an example of data obtained in the height displacement measuring step. In FIG. 3, the position of the chuck table 16 (position in the X-axis direction) is on the horizontal axis, and the height of the holding surface 16a (position in the Z-axis direction) is on the vertical axis. The obtained height position data is stored in the memory 42 b of the control unit 42.

  After the height displacement measuring step, a holding step for holding the workpiece 11 with the chuck table 16 is performed. Specifically, the negative pressure of the suction source is applied to the holding surface 16a of the chuck table 16 with the lower surface 11b side of the workpiece 11 overlapped. As a result, the workpiece 11 is sucked and held on the chuck table 16 with the upper surface 11a exposed upward.

  After the holding step, the upper surface 11a side of the workpiece 11 is ground while moving the grinding wheel 40b up and down in accordance with the displacement of the height position of the holding surface 16a of the chuck table 16 measured in the height displacement measuring step. A grinding process is performed. FIG. 4 is a side view schematically showing the grinding process.

  In the grinding step, first, the horizontal movement mechanism 4 moves the chuck table 16 holding the workpiece 11 to a position that does not overlap the grinding wheel 40 in plan view. Further, the lower surface of the grinding wheel 40 b is positioned at a position slightly lower than the upper surface 11 a of the workpiece 11 by the lifting mechanism 20. The height at which the lower surface of the grinding wheel 40b is positioned is adjusted according to the finished thickness of the workpiece 11 and the like.

  In this state, the chuck table 16 is moved in the horizontal direction (direction parallel to the holding surface 16a) while rotating the grinding wheel 40. At the same time, the control unit 42 (CPU 42a) moves the grinding wheel 40b up and down according to this data while referring to the data stored in the memory 42b.

  That is, the grinding wheel 40b is moved up and down in accordance with the vertical displacement of the chuck table 16. Thus, the distance between the grinding surface of the grinding wheel 40b and the holding surface 16a is set to a predetermined value by moving the grinding wheel 40b up and down in accordance with the displacement of the height position of the holding surface 16a measured in the height displacement measuring step. Can be kept at a distance.

  Thereby, for example, even when the horizontal guide rail 6 has a vertical undulation and the holding surface 16a of the chuck table 16 is displaced vertically, the distance between the grinding surface of the grinding wheel 40b and the holding surface 16a is set to a predetermined value. The workpiece 11 can be ground while maintaining the distance. As a result, the flatness of the workpiece 11 can be ensured by grinding.

  The moving speed of the chuck table 16 in the horizontal direction is arbitrary. It is sufficient that the grinding wheel 40b can follow at least the displacement of the chuck table 16 in the vertical direction.

  As described above, the grinding method according to the present embodiment includes the height displacement measuring step for measuring the displacement of the height position of the holding surface 16a of the chuck table 16 in advance, and the chuck table 16 measured in the height displacement measuring step. A grinding step of grinding the workpiece 11 while moving the grinding wheel 40b up and down in accordance with the displacement of the height position of the holding surface 16a, so that even when the holding surface 16a of the chuck table 16 is displaced up and down The workpiece 11 can be ground while maintaining the distance between the grinding surface of the grinding wheel 40b and the holding surface 16a at a predetermined distance.

  As described above, in the grinding method of the present embodiment, the workpiece 11 is ground at a predetermined distance from the holding surface 16a. Therefore, even when the holding surface 16a of the chuck table 16 is displaced up and down, Flatness can be ensured.

  In addition, this invention is not limited to description of the said embodiment, A various change can be implemented. For example, in a situation where the reproducibility of the height position of the holding surface 16a is ensured, a plurality of holding steps and grinding steps may be performed for one height displacement measuring step.

  In the above embodiment, the workpiece 11 is ground by moving the chuck table 16 in a direction parallel to the holding surface 16a. However, at least the chuck table 16 and the grinding wheel 40b are parallel to the holding surface 16a. What is necessary is just to be able to grind the workpiece 11 by moving relatively in the direction.

  Moreover, although the grinding apparatus 2 provided with the displacement meter 44 is illustrated in the said embodiment, a displacement meter may be attached to a grinding apparatus only at the time of a measurement. That is, the grinding device may not include a displacement meter.

  In addition, the configurations, methods, and the like according to the above-described embodiments can be appropriately modified and implemented without departing from the scope of the object of the present invention.

11 Workpiece 11a Upper surface 11b Lower surface 2 Grinding device 4 Horizontal movement mechanism 6 Horizontal guide rail 8 Horizontal movement table 10 Horizontal ball screw 12 Horizontal pulse motor 14 Support base 16 Chuck table 16a Holding surface 18 Support structure 20 Elevating mechanism 22 Elevating guide rail 24 Lift table 26 Lift ball screw 28 Lift pulse motor 30 Fixture 32 Grinding mechanism 34 Spindle housing 36 Spindle 38 Wheel mount 40 Grinding wheel 40a Wheel base 40b Grinding wheel 42 Control unit 42a CPU
42b Memory 44 Displacement meter

Claims (1)

A plate-like workpiece is held on the holding surface of the chuck table, and a grinding surface of a rotating grinding wheel is applied to the upper surface side of the workpiece held on the holding surface of the chuck table, and the chuck table and the grinding are applied. A grinding method for grinding a top surface side of a workpiece by moving a grindstone relative to a direction parallel to the holding surface,
A height displacement measuring step for measuring in advance a displacement of a height position of the holding surface of the chuck table when the chuck table passes through a position corresponding to an operating position at which the grinding surface acts on the workpiece;
A holding step for holding a workpiece on the chuck table;
The grinding surface and the holding surface are moved up and down in accordance with the displacement of the height position of the holding surface of the chuck table measured by the height displacement measuring step. And a grinding step of grinding the upper surface side of the workpiece while maintaining the distance to the predetermined distance.