JP2024098896A - Grinding device and grinding method - Google Patents

Abstract

To provide a grinding device and a grinding method which can directly monitor the grinding quality of a workpiece.SOLUTION: A grinding device 1 includes: a chuck table 10; a grinding unit 20 for grinding a workpiece 100 held on the chuck table 10; a grinding feeding unit 30; a contact type thickness measurement unit 40 which has a first probe 41 and a second probe 42; and a control unit 60. The control unit 60 includes: a thickness calculation part 61 which calculates the thickness of the workpiece 100 from a difference between data of the position of a holding surface 13 measured by the first probe 41 and data of the upper surface position of the workpiece 100 measured by the second probe 42; and a determination part 62 which determines whether or not a time change of the thickness of the workpiece 100 calculated by the thickness calculation part 61 is consistent with a grinding speed of grinding the workpiece 100 or within the allowable range. The control unit continues grinding when the time change is consistent or within the allowable range, and reports an error when the time change is out of the allowable range.SELECTED DRAWING: Figure 1

Description

The present invention relates to a grinding device and a grinding method.

A semiconductor wafer (workpiece) on which numerous devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are formed and each device is partitioned by planned dividing lines (streets), the back side is ground by a grinding device to a specified thickness, and then a dicing device cuts the planned dividing lines to divide the wafer into individual devices. The divided devices are then used in electrical equipment such as mobile phones and personal computers.

In such grinding devices, a configuration is known in which the power supplied to the motor that drives the spindle on which the grinding wheel is attached is used as the load current value to detect grinding abnormalities (see, for example, Patent Document 1).

JP 2011-143516 A

However, there was a problem with detecting the load current value, in that there was a large time lag between when a machining abnormality occurred and when a change in the load current value occurred. In addition, there was also a problem in that, because the load relative to the rotation direction of the spindle was detected, it was not possible to directly monitor whether the workpiece was being ground or not.

The present invention was made in consideration of these problems, and its purpose is to provide a grinding device and a grinding method that can directly monitor the quality of grinding of a workpiece.

In order to solve the above-mentioned problems and achieve the object, the grinding device of the present invention is a grinding device for grinding a plate-shaped workpiece, and includes a chuck table that holds the workpiece on a holding surface, a grinding unit that has a grinding wheel attached to the tip of a spindle and is arranged opposite the holding surface of the chuck table to grind the workpiece held on the chuck table, a grinding feed unit that moves the grinding unit and the chuck table relatively close to and away from each other, a first probe that measures the position of the holding surface outside the workpiece on the holding surface that holds the workpiece, and a grinding feed unit that moves the grinding unit and the chuck table relatively close to and away from each other. The contact thickness measurement unit includes a second probe that measures the top surface position of the workpiece, and a control unit that controls each component. The control unit has a thickness calculation section that calculates the thickness of the workpiece from the difference between the data measured by the first probe and the data measured by the second probe, and a judgment section that judges whether the change in thickness of the workpiece calculated by the thickness calculation section over time matches the grinding speed for grinding the workpiece or is within an acceptable range, and if it matches or is within the acceptable range, continues grinding, and if it is outside the acceptable range, reports an error.

The control unit may store the origin positions of the first probe and the second probe before grinding, and may determine the moment when the value changes from the origin position as the timing when contact between the grinding wheel and the workpiece begins. If the change in thickness of the workpiece calculated by the thickness calculation unit over time does not match the grinding speed at which the workpiece is ground, or if the state is outside the allowable range and continues for a predetermined time or longer from the timing when contact begins, an error may be reported.

In order to solve the above-mentioned problems and achieve the object, the grinding method of the present invention is a grinding method for grinding a plate-shaped workpiece, comprising: a holding step of holding the workpiece on the holding surface of a chuck table; and a grinding step of grinding the workpiece while measuring the thickness of the workpiece with a contact thickness measuring unit having a first probe that measures the position of the holding surface outside the workpiece on the holding surface holding the workpiece and a second probe that measures the position of the top surface of the workpiece held on the holding surface, the grinding step is characterized in that while grinding the workpiece, the thickness of the workpiece is calculated from the difference between the change in the position of the holding surface and the change in the top surface position of the workpiece, and grinding is continued if the change in the thickness of the workpiece coincides with the grinding speed for grinding the workpiece or is within an allowable range, and an error is notified if it is outside the range.

The grinding step may store the origin positions of the first probe and the second probe before grinding, and may determine the moment when the value changes from the origin position as the timing when contact between the grinding wheel and the workpiece begins. An error may be reported if the change in thickness of the workpiece over time calculated by the thickness calculation unit does not match the grinding speed at which the workpiece is ground, or if the state is outside the allowable range and continues for a predetermined time or more from the timing when contact begins.

The present invention calculates the thickness of the workpiece from the difference between the two heights measured by the first and second probes, and determines whether the grinding of the workpiece is normal or not based on whether the time change in the thickness of the workpiece and the grinding speed at which the workpiece is ground match or are within an acceptable range, so that it is possible to directly monitor whether the workpiece is being ground.

FIG. 1 is a perspective view showing an example of the configuration of a grinding device according to an embodiment. FIG. 2 is a cross-sectional view showing a main part of the grinding apparatus of FIG. FIG. 3 is a graph showing a first example of the measurement results obtained by the contact type thickness measuring unit of the grinding apparatus of FIG. FIG. 4 is a graph showing a second example of the measurement results obtained by the contact type thickness measuring unit of the grinding apparatus of FIG. FIG. 5 is a graph showing a third example of the measurement results obtained by the contact type thickness measuring unit of the grinding apparatus of FIG. FIG. 6 is a graph showing a fourth example of the measurement results obtained by the contact type thickness measuring unit of the grinding apparatus of FIG. FIG. 7 is a flowchart illustrating an example of a processing procedure of the grinding method according to the embodiment.

The following describes in detail the form (embodiment) for carrying out the present invention with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. The components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Various omissions, substitutions, or modifications of the configuration can be made without departing from the spirit of the present invention.

[Embodiment]
A grinding device 1 and a grinding method according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing a configuration example of the grinding device 1 according to the embodiment. Fig. 2 is a cross-sectional view showing a main part of the grinding device 1 of Fig. 1. As shown in Fig. 1, the grinding device 1 according to the embodiment includes a chuck table 10, a grinding unit 20, a grinding feed unit 30, a contact type thickness measurement unit 40, a notification unit 50, and a control unit 60. In this embodiment, the grinding device 1 further includes a turntable 19, cassettes 71 and 72, an alignment unit 73, a carry-in unit 74, a carry-out unit 75, a cleaning unit 76, and a carry-in/out unit 77.

In this embodiment, the workpiece 100 to be ground by the grinding device 1 according to the embodiment is, as shown in FIG. 1, a disk-shaped semiconductor wafer or an optical device wafer, for example, made of silicon, sapphire, silicon carbide (SiC), gallium arsenide, or the like. The workpiece 100 has a flat surface, and chip-shaped devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integrations) are formed in each area defined by planned division lines (streets) that intersect with each other (in this embodiment, they are perpendicular). The back surface of the back side of the front surface of the workpiece 100 is ground to thin it to a predetermined thickness, and then the workpiece 100 is divided along the planned division lines by a cutting device or the like to manufacture individual semiconductor device chips. The workpiece 100 is not limited to this in the present invention, and may be a disk-shaped package substrate having a plurality of devices sealed with resin, a ceramic plate, a glass plate, or the like.

As shown in FIG. 2, the chuck table 10 comprises a disk-shaped frame 11 with a recess formed therein, and a disk-shaped suction portion 12 fitted into the recess. The suction portion 12 of the chuck table 10 is formed from a porous ceramic or the like with a large number of porous holes, and is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). The upper surface of the suction portion 12 of the chuck table 10 is a holding surface 13 that suction-holds the placed workpiece 100 from below.

In this embodiment, as shown in FIG. 2, the upper surface of the frame 11 and the holding surface 13 are formed into a conical surface with a slightly lower outer periphery and a vertex at the center 14 of the holding surface 13 of the chuck table 10. The chuck table 10 is provided so as to be freely rotatable by a rotary drive source 15 about a predetermined rotation axis that passes through the center 14 of the holding surface 13 and is perpendicular to the bottom surface of the cone that forms the holding surface 13, independently of a turntable 19, which will be described later. Note that the holding surface 13 is not limited to this in the present invention, and may be formed flat.

A rotation axis adjustment unit 16 is provided below the chuck table 10, which tilts the rotation axis of the chuck table 10 with respect to the Z-axis direction parallel to the vertical direction. In the example shown in FIG. 2, the rotation axis of the chuck table 10 is tilted at a predetermined angle with respect to the Z-axis direction parallel to the vertical direction, and accordingly, the holding surface 13 is tilted at the same angle with respect to a horizontal plane parallel to the XY plane, with the bottom surface of the cone forming the holding surface 13. Note that the present invention is not limited to this, and the holding surface 13 does not have to be tilted with respect to the horizontal plane.

In the embodiment, the grinding device 1 is provided with three chuck tables 10. As shown in FIG. 1, the three chuck tables 10 are arranged at equal intervals, for example at a phase angle of 120°, on a disk-shaped turntable 19 that is larger than the chuck table 10 in a plan view. Note that the number of chuck tables 10 is not limited to this in the present invention, and there may be one, two, or four or more chuck tables 10. The turntable 19 is provided so as to be freely rotatable in a horizontal plane, and is rotated at a predetermined timing. The three chuck tables 10 are moved sequentially to the loading/unloading position 201, the first grinding position 202-1, the second grinding position 202-2, and the loading/unloading position 201 by the rotation of the turntable 19. In addition, when there is no need to distinguish between the first grinding position 202-1 and the second grinding position 202-2, the reference numerals will be omitted as appropriate, without adding "-1" or "-2" after the reference numerals, as they are common to both.

In this embodiment, the grinding unit 20 includes a first grinding unit 20-1 and a second grinding unit 20-2, as shown in FIG. 1. Both the first grinding unit 20-1 and the second grinding unit 20-2 grind the workpiece 100 held on the chuck table 10. Hereinafter, when each part related to the first grinding unit 20-1 is to be distinguished from each part related to the second grinding unit 20-2, "-1" is added after the reference numeral, and when each part related to the second grinding unit 20-2 is to be distinguished from each part related to the first grinding unit 20-1, "-2" is added after the reference numeral. When it is not necessary to distinguish between the first grinding unit 20-1 and the second grinding unit 20-2, the corresponding parts are considered to be common to both, and are appropriately omitted without adding "-1" or "-2" after the reference numeral.

As shown in Figs. 1 and 2, the grinding unit 20 includes a spindle 21, a grinding wheel 22, and a grinding fluid supply unit 24. The spindle 21 is rotatably mounted around an axis parallel to the vertical direction (Z-axis direction) and supports the grinding wheel 22, which is detachably attached to the lower end, so that the grinding wheel 22 is rotatable around an axis parallel to the vertical direction. The grinding wheel 22 has grinding stones 23 arranged in a ring shape on its underside.

The grinding unit 20 is arranged so that the spindle 21 faces the holding surface 13 of the chuck table 10 positioned at the grinding position 202 in the vertical direction (Z-axis direction). In this embodiment, as shown in FIG. 1, the grinding unit 20-1 is arranged to face the holding surface 13 of the chuck table 10 positioned at the grinding position 202-1, and the grinding unit 20-2 is arranged to face the holding surface 13 of the chuck table 10 positioned at the grinding position 202-2. The grinding fluid supply unit 24 supplies a grinding fluid such as pure water to the workpiece 100 held by the chuck table 10 positioned at the grinding position 202.

In this embodiment, the grinding feed unit 30 includes a first grinding feed unit 30-1 and a second grinding feed unit 30-2, as shown in FIG. 1. When there is no need to distinguish between the first grinding feed unit 30-1 and the second grinding feed unit 30-2, the symbols are omitted as appropriate, without adding "-1" or "-2" after the reference numerals, as they are common to both.

The grinding feed unit 30 moves the grinding unit 20 relative to the chuck table 10 positioned at the grinding position 202 along the grinding feed direction (Z-axis direction parallel to the vertical direction) to move the grinding unit 20 and the chuck table 10 positioned at the grinding position 202 closer to and farther apart from each other along the grinding feed direction. In this embodiment, as shown in FIG. 1, the grinding feed unit 30-1 moves the grinding unit 20-1 relative to the chuck table 10 positioned at the grinding position 202-1 along the grinding feed direction to move the grinding unit 20-1 and the chuck table 10 positioned at the grinding position 202-1 closer to and farther apart from each other along the grinding feed direction. In addition, the grinding feed unit 30-2 moves the grinding unit 20-2 relative to the chuck table 10 positioned at the grinding position 202-2 along the grinding feed direction, thereby moving the grinding unit 20-2 and the chuck table 10 positioned at the grinding position 202-2 closer to and farther apart from each other along the grinding feed direction.

The grinding feed unit 30 is a known ball screw mechanism having a motor, a ball screw, and a guide. The grinding feed unit 30 is configured to have a ball screw that is rotatable around the axis of the Z axis, a motor that rotates the ball screw around the axis, and a guide that supports the grinding unit 20 so that it can move in the Z axis direction. The grinding feed unit 30 has a control unit 60 that controls the drive of the motor, thereby controlling the grinding speed (grinding feed speed) and grinding amount (grinding feed amount) at which the grinding unit 20 grinds the workpiece 100. Here, the grinding speed at which the grinding unit 20 grinds the workpiece 100 refers to the speed at which the grinding unit 20 moves relatively closer to and away from the chuck table 10 positioned at the grinding position 202 along the Z-axis direction by the grinding feed unit 30 while the grinding unit 20 is grinding the workpiece 100 held on the chuck table 10 positioned at the grinding position 202. Also, the grinding amount at which the grinding unit 20 grinds the workpiece 100 refers to the amount (height) at which the grinding unit 20 moves relatively closer to and away from the chuck table 10 positioned at the grinding position 202 along the Z-axis direction by the grinding feed unit 30 while the grinding unit 20 is grinding the workpiece 100 held on the chuck table 10 positioned at the grinding position 202. The grinding speed is the amount of grinding per unit time.

The grinding feed unit 30 includes an encoder that reads the rotational position of the motor, and detects the relative position in the Z-axis direction with respect to the chuck table 10 positioned at the grinding position 202 of the grinding unit 20 based on the rotational position of the motor read by the encoder, and outputs the detected relative position to the control unit 60. Here, the relative position in the Z-axis direction is determined using the device Cartesian coordinate system (XYZ coordinates) provided in the grinding device 1. The device Cartesian coordinate system is set, for example, to the center on the turntable 19 as the origin. In addition, the grinding feed unit 30 detects the relative position in the Z-axis direction with respect to the chuck table 10 positioned at the grinding position 202 of the grinding unit 20, for example, at regular intervals (for example, every second) before the start of grinding, during grinding, and after the end of grinding, thereby detecting the grinding speed and grinding amount at which the grinding unit 20 grinds the workpiece 100, and outputting the detected grinding speed and grinding amount to the control unit 60. The grinding feed unit 30 is not limited to a configuration that detects the relative position in the Z-axis direction with respect to the chuck table 10 positioned at the grinding position 202 of the grinding unit 20 using an encoder, but may also be configured with a linear scale parallel to the Z-axis direction and a reading head that is movable in the Z-axis direction by the grinding feed unit 30 and reads the graduations of the linear scale.

In the grinding unit 20, the spindle 21 is rotated around an axis parallel to the vertical direction, thereby rotating the grinding wheel 22 attached to the lower end of the spindle 21 around an axis parallel to the vertical direction, and the chuck table 10 holding the workpiece 100, which is positioned at the grinding position 202 and arranged opposite the spindle 21, is rotated around the rotation axis. While supplying grinding fluid to the workpiece 100 held on the rotated chuck table 10 by the grinding fluid supply unit 24, the grinding feed unit 30 presses the rotating grinding wheel 22 along the grinding feed direction, thereby grinding the workpiece 100 with the grinding stone 23 of the grinding wheel 22. The grinding wheel 22 grinds the workpiece 100 along the grinding surface to form the grinding surface of the workpiece 100 parallel to the grinding surface. In this embodiment, the grinding unit 20-1 grinds and feeds the grinding wheel 22 by the grinding feed unit 30-1 to the workpiece 100 held on the chuck table 10 positioned at the grinding position 202-1, and grinds the workpiece 100 held on the chuck table 10 positioned at the grinding position 202-1. The grinding unit 20-2 grinds and feeds the grinding wheel 22 by the grinding feed unit 30-2 to the workpiece 100 held on the chuck table 10 positioned at the grinding position 202-2, and grinds the workpiece 100 held on the chuck table 10 positioned at the grinding position 202-2.

In this embodiment, the grinding unit 20 may be configured such that, for example, grinding unit 20-1 is a rough grinding unit that roughly grinds the workpiece 100 with a rough grinding wheel, and grinding unit 20-2 is a finish grinding unit that finishes the workpiece 100 with a finish grinding wheel, and the workpiece 100 is roughly ground by grinding unit 20-1 and then finish ground by grinding unit 20-2.

In this embodiment, as shown in FIG. 1, the contact type thickness measurement units 40 are provided at two locations, near the first grinding position 202-1 and near the second grinding position 202-2. The two contact type thickness measurement units 40 have the same configuration and the same functions, except for the locations where they are provided. As shown in FIG. 1, the contact type thickness measurement unit 40 includes a first probe 41 and a second probe 42. In this embodiment, the first probe 41 and the second probe 42 are both contact type probes that measure the height of the position where they come into contact.

The first probe 41 contacts the outside of the workpiece 100 on the holding surface 13 of the chuck table 10 holding the workpiece 100, thereby measuring the position of the holding surface 13 in the Z-axis direction, i.e., the height of the holding surface 13. The second probe 42 contacts the top surface (surface to be ground) of the workpiece 100 held on the holding surface 13 of the chuck table 10, thereby measuring the position of the top surface of the workpiece 100 in the Z-axis direction (top surface position), i.e., the height of the top surface of the workpiece 100 (top surface height). Both the first probe 41 and the second probe 42 output the measured position (height) results to the control unit 60. In addition, both the first probe 41 and the second probe 42 detect the height of the holding surface 13 of the chuck table 10 and the height of the top surface of the workpiece 100 before grinding begins, during grinding, and after grinding ends, for example, at regular intervals (for example, every second), to obtain the time change in the height of the holding surface 13 and the time change in the height of the top surface of the workpiece 100, and output these obtained time changes to the control unit 60.

1, the notification unit 50 includes a display unit 51 and a light-emitting unit 52. The display unit 51 is provided on a cover (not shown) of the grinding device 1 with the display surface facing outward. The display unit 51 displays a screen for setting various conditions related to various processes of the grinding device 1, such as the process by the grinding unit 20 and the measurement by the contact-type thickness measurement unit 40, as well as acquired images and data, the calculation results by the thickness calculation unit 61, and the judgment results by the judgment unit 62, so that the operator can visually confirm them. The display unit 51 is configured with a liquid crystal display device or the like. The display unit 51 is provided with an input unit that is used when the operator inputs information related to the above-mentioned various conditions of the grinding device 1 and information related to the display of images, etc. The input unit provided in the display unit 51 is configured with at least one of a touch panel provided in the display unit 51 and a keyboard, etc. The display unit 51 is not fixed to the grinding device 1, but is provided in an arbitrary communication device, and the arbitrary communication device may be connected to the grinding device 1 wirelessly or by wire.

The light-emitting unit 52 is provided above a cover (not shown) of the grinding device 1. In this embodiment, the light-emitting unit 52 is composed of a light-emitting diode or the like, and by lighting up, blinking, changing the color of light, etc., it notifies the operator in a recognizable manner of errors that occur during various processes by the grinding device 1, the calculation results by the thickness calculation unit 61, the judgment results by the judgment unit 62, etc.

In the present invention, the notification unit 50 is not limited to the display unit 51 or the light-emitting unit 52, but may be an audio unit composed of a speaker or the like that emits sound, and the operator may be notified of any errors that have occurred, the calculation results by the thickness calculation unit 61, the judgment results by the judgment unit 62, etc. in a recognizable manner by the sound of the audio unit.

The control unit 60 controls the operation of various components of the grinding device 1 to cause the grinding device 1 to perform grinding processing of the workpiece 100, including the grinding method according to the embodiment. While the grinding unit 20 is grinding the workpiece 100, the control unit 60 acquires, via the grinding feed unit 30, the grinding speed and grinding amount at which the grinding unit 20 grinds the workpiece 100.

3, 4, 5, and 6 are graphs showing a first example, a second example, a third example, and a fourth example of the measurement results by the contact type thickness measurement unit 40 of the grinding device 1 of FIG. 1, respectively. The graphs shown in FIG. 3, 4, 5, and 6 all show the time change of the measurement results by the contact type thickness measurement unit 40 after the grinding wheel 22 starts to contact the workpiece 100 held on the chuck table 10. During grinding of the workpiece 100 by the grinding unit 20, the control unit 60 acquires data 151 of the height of the holding surface 13 of the chuck table 10 measured by the first probe 41 and data 152 of the height of the upper surface of the workpiece 100 measured by the second probe 42 by the contact type thickness measurement unit 40, as shown in FIG. 3, 4, 5, and 6.

The data 151 of the height of the holding surface 13 of the chuck table 10 measured by the first probe 41 is the change in height of the holding surface 13 over time while the workpiece 100 is being ground by the grinding unit 20, as shown in Figures 3, 4, 5, and 6. The data 152 of the height of the top surface of the workpiece 100 measured by the second probe 42 is the change in height of the top surface of the workpiece 100 over time while the workpiece 100 is being ground by the grinding unit 20, as shown in Figures 3, 4, 5, and 6.

In the first, second, third and fourth examples, the heights of the holding surface 13 and the top surface of the workpiece 100 shown in data 151 and 152, respectively, are all reduced by the same height in region 161 from the timing when the grinding wheel 22 starts to come into contact with the workpiece 100 until a certain time (for example, several seconds in this embodiment) has elapsed, as shown in Figures 3, 4, 5 and 6. This phenomenon represents a phenomenon in which the chuck table 10 holding the workpiece 100 sinks vertically downward until the grinding wheel 22 actually starts to grind the workpiece 100 due to the impact generated when the grinding wheel 22 comes into contact with the workpiece 100 held on the chuck table 10.

Therefore, the control unit 60 pre-stores the origin positions of the first probe 41 and the second probe 42 before grinding, and detects the moment when the heights measured by the first probe 41 and the second probe 42 change from their respective origin positions as the timing when contact between the grinding wheel 22 and the workpiece 100 begins.

The control unit 60 includes a thickness calculation unit 61 and a judgment unit 62. The thickness calculation unit 61 calculates the thickness of the workpiece 100 from the difference between the data 151 of the height of the holding surface 13 measured by the first probe 41 and the data 152 of the height of the top surface of the workpiece 100 measured by the second probe 42. Specifically, the thickness calculation unit 61 calculates the thickness of the workpiece 100 by subtracting the data 151 of the height of the holding surface 13 measured by the first probe 41 from the data 152 of the height of the top surface of the workpiece 100 measured by the second probe 42. Similarly, the thickness calculation unit 61 calculates the change in thickness of the workpiece 100 over time. The judgment unit 62 judges whether the change in thickness of the workpiece 100 over time calculated by the thickness calculation unit 61 matches or is within an allowable range with the grinding speed for grinding the workpiece 100 acquired by the grinding feed unit 30.

When the determination unit 62 determines whether or not there is a match, if the change in thickness of the workpiece 100 over time calculated by the thickness calculation unit 61 matches the grinding speed at which the workpiece 100 is ground obtained by the grinding feed unit 30, it determines that there is a match and that the workpiece 100 is being ground normally, and if the change in thickness of the workpiece 100 over time calculated by the thickness calculation unit 61 does not match the grinding speed at which the workpiece 100 is ground obtained by the grinding feed unit 30, i.e., they do not match, it determines that there is a mismatch and that the workpiece 100 is not being ground normally.

When the determination unit 62 determines whether the thickness is within the allowable range, if the difference between the change over time of the thickness of the workpiece 100 calculated by the thickness calculation unit 61 and the grinding speed at which the workpiece 100 is ground obtained by the grinding feed unit 30 is within the allowable range, the determination unit 62 determines that the thickness is within the allowable range and that the workpiece 100 is being ground normally, and if the difference between the change over time of the thickness of the workpiece 100 calculated by the thickness calculation unit 61 and the grinding speed at which the workpiece 100 is ground obtained by the grinding feed unit 30 is not within the allowable range, i.e., outside the allowable range, the determination unit 62 determines that the thickness is outside the allowable range and that the workpiece 100 is not being ground normally.

When a strict judgment is required, the judgment unit 62 can judge whether or not there is a match. When a judgment is required that takes into account variations that may occur momentarily, such as the wear timing of the grinding stone 23 of the grinding wheel 22 and the measurement tolerances of the first probe 41 and the second probe 42, the judgment unit 62 can set an acceptable range equivalent to the variation in advance and judge whether or not there is an acceptable range.

When the determination unit 62 determines that the results are "matched or within the allowable range", the control unit 60 determines that the workpiece 100 is being ground normally, and continues grinding the workpiece 100 by the grinding unit 20. When the determination unit 62 determines that the results are "not matched or outside the allowable range", the control unit 60 determines that the workpiece 100 is not being ground normally, and notifies the notification unit 50 of an error. In order to prevent the control unit 60 from erroneously notifying the sinking phenomenon of the chuck table 10 that occurs at the start of grinding as an error, the control unit 60 may cause the notification unit 50 to notify an error when the state in which the determination unit 62 determines that the results are "not matched or outside the allowable range" continues for a predetermined time or more from the start of contact between the grinding wheel 22 and the workpiece 100. Here, the predetermined time is set to an appropriate value that is slightly longer than the certain time during which the sinking phenomenon of the chuck table 10 occurs at the start of contact between the grinding wheel 22 and the workpiece 100.

When the grinding unit 20 is grinding the workpiece 100 normally, as shown in the first example of FIG. 3, the height of the holding surface 13 indicated by data 151 remains constant and does not change, and the height of the upper surface of the workpiece 100 indicated by data 152 decreases at a constant speed according to the grinding speed detected by the grinding feed unit 30, and as a result, the thickness of the workpiece 100 calculated by the thickness calculation unit 61 decreases at the same constant speed. In such a case, the change over time in the thickness of the workpiece 100 calculated by the thickness calculation unit 61 and the grinding speed for grinding the workpiece 100 obtained by the grinding feed unit 30 match or are within the allowable range, and are determined to be "matched or within the allowable range" by the determination unit 62.

On the other hand, when the grinding unit 20 is not grinding the workpiece 100 normally, the data 151 and 152 show a change different from that of the first example of FIG. 3, as shown in the region 162 of the second example of FIG. 4, the region 163 of the third example of FIG. 5, and the region 164 of the fourth example of FIG. 6. For example, as shown in the region 162 of the second example of FIG. 4, after the phenomenon of the chuck table 10 sinking occurs at the timing when the grinding wheel 22 and the workpiece 100 start to come into contact with each other and subsides, the height of the holding surface 13 and the height of the upper surface of the workpiece 100 shown in the data 151 and 152, respectively, decrease by the same height at the same speed as the decrease in the height of the upper surface of the workpiece 100 shown in the data 152 when the workpiece 100 is being ground normally. This phenomenon indicates that the chuck table 10 holding the workpiece 100 sinks vertically downward, causing a grinding abnormality in which the workpiece 100 is not ground.

As shown in region 163 of the third example in FIG. 5, the sinking of the chuck table 10 occurs at the timing when the grinding wheel 22 and the workpiece 100 start to come into contact with each other, and then after this subsides, normal grinding of the workpiece 100 is performed, and then the height of the holding surface 13 and the height of the top surface of the workpiece 100, which are shown in data 151 and 152, respectively, are both constant and do not change. This phenomenon indicates that a grinding abnormality occurs in which the workpiece 100 is not ground, and that the chuck table 10 holding the workpiece 100 is not sinking.

6, after the chuck table 10 sinks at the start of contact between the grinding wheel 22 and the workpiece 100, the height of the holding surface 13 and the height of the top surface of the workpiece 100 shown in data 151 and 152, respectively, decrease at a slower rate than the decrease in the height of the top surface of the workpiece 100 shown in data 152 when the workpiece 100 is being ground normally, as shown in region 164 of the fourth example in FIG. 6. This phenomenon indicates that the workpiece 100 is being ground, but the change in thickness of the workpiece 100 over time is smaller than the grinding speed set by the grinding feed unit 30, and the chuck table 10 holding the workpiece 100 sinks vertically downward, causing the load on the grinding to gradually increase. Specifically, in such a case, for example, the grinding speed set by the grinding feed unit 30 is 4 μm/s, so when the workpiece 100 is being ground normally, the rate at which the height of the upper surface of the workpiece 100 decreases as shown in data 152 is 4 μm/s. However, an abnormal grinding occurs in which the time change in the thickness of the workpiece 100 caused by the grinding wheel 22 actually grinding the workpiece 100 decreases to 2 μm/s, so in the fourth example region 164 in FIG. 5, the rates at which the height of the holding surface 13 and the height of the upper surface of the workpiece 100 decrease are both 2 μm/s, as shown in data 151 and 152, respectively.

In this way, if the grinding unit 20 is not grinding the workpiece 100 normally, the change in thickness of the workpiece 100 over time calculated by the thickness calculation unit 61 and the grinding speed for grinding the workpiece 100 obtained by the grinding feed unit 30 will not match or will be outside the allowable range, and the determination unit 62 will determine that they "do not match or are outside the allowable range."

In this embodiment, the control unit 60 includes a computer system. The computer system included in the control unit 60 includes an arithmetic processing device having a microprocessor such as a CPU (Central Processing Unit), a storage device having a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and an input/output interface device. The arithmetic processing device of the control unit 60 performs arithmetic processing according to a computer program stored in the storage device of the control unit 60, and outputs control signals for controlling the grinding device 1 to each component of the grinding device 1 via the input/output interface device of the control unit 60. In this embodiment, the functions of the thickness calculation unit 61 and the determination unit 62 are both realized by the arithmetic processing device of the control unit 60 executing a computer program stored in the storage device.

As shown in FIG. 1, the cassettes 71 and 72 are containers for storing multiple workpieces 100. The alignment unit 73 is a table on which the workpieces 100 removed from the cassettes 71 and 72 are temporarily placed and their center alignment is performed.

The carry-in unit 74 has a suction pad, and adsorbs and holds the workpiece 100 before grinding that has been aligned by the alignment unit 73, and carries it onto the chuck table 10 positioned at the carry-in/carry-out position 201. The carry-out unit 75 adsorbs and holds the workpiece 100 after grinding that is held on the chuck table 10 positioned at the carry-in/carry-out position 201, and carries it out to the cleaning unit 76. The cleaning unit 76 cleans the workpiece 100 after grinding, and removes contamination such as grinding debris adhering to the ground surface.

As shown in FIG. 1, the carry-in/out unit 77 is, for example, a robot pick equipped with a U-shaped hand, and transports the workpiece 100 by suction and holding it with the U-shaped hand. Specifically, the carry-in/out unit 77 carries the workpiece 100 before grinding out of the cassettes 71 and 72 to the alignment unit 73, and carries the workpiece 100 after grinding out of the cleaning unit 76 into the cassettes 71 and 72.

Next, this specification describes a grinding method according to an embodiment with reference to the drawings. FIG. 7 is a flowchart showing an example of a processing procedure of the grinding method according to the embodiment. The grinding method according to the embodiment is an example of an operation process performed by the grinding device 1 according to the embodiment, and includes a holding step 1001 and a grinding step 1002 as shown in FIG. 7.

The holding step 1001 is a step in which the workpiece 100 is held on the holding surface 13 of the chuck table 10. In the holding step 1001, specifically, the carry-in/out unit 77 first carries out the workpiece 100 before grinding housed in the cassettes 71 and 72 and transports it to the alignment unit 73, and the alignment unit 73 aligns the center of the carried workpiece 100 before grinding. The carry-in unit 74 then carries the workpiece 100 before grinding centered by the alignment unit 73 onto the holding surface 13 of the chuck table 10 positioned at the carry-in/carry-out position 201. In the holding step 1001, the workpiece 100 before grinding carried onto the holding surface 13 of the chuck table 10 is then suction-held from the surface (front surface) opposite to the grinding surface of the workpiece 100 by the holding surface 13 of the chuck table 10. In the holding step 1001, the turntable 19 is then rotated to move the chuck table 10, which holds the workpiece 100 before grinding on the holding surface 13, from the carry-in/carry-out position 201 to the grinding position 202.

Grinding step 1002 is a step in which the grinding unit 20, which includes a spindle 21 with a grinding wheel 22 attached to its tip, and the chuck table 10 are brought closer together while rotating, and the workpiece 100 is ground while measuring the thickness of the workpiece 100 using a contact thickness measurement unit 40 equipped with a first probe 41 that measures the position (height) of the holding surface 13 on the outside of the workpiece 100 that holds the workpiece 100, and a second probe 42 that measures the top surface position (height) of the workpiece 100 held on the holding surface 13.

In the grinding step 1002, specifically, the spindle 21 is first rotated around an axis parallel to the vertical direction, thereby rotating the grinding wheel 22 attached to the lower end of the spindle 21 around an axis parallel to the vertical direction, and the chuck table 10, which is positioned at the grinding position 202 and opposed to the spindle 21 and holds the workpiece 100, is rotated around its rotation axis. In the grinding step 1002, the grinding wheel 22 rotated by the grinding feed unit 30 is pressed along the grinding feed direction while the grinding fluid supply unit 24 supplies grinding fluid to the workpiece 100 held on the rotated chuck table 10, thereby grinding the workpiece 100 with the grinding stone 23 of the grinding wheel 22.

In the grinding step 1002, the grinding unit 20 grinds the workpiece 100, and the contact type thickness measurement unit 40 measures the height of the holding surface 13 by contacting the outside of the workpiece 100 on the holding surface 13 of the chuck table 10 holding the workpiece 100 with the first probe 41, and measures the height of the upper surface of the workpiece 100 by contacting the upper surface of the workpiece 100 held on the holding surface 13 of the chuck table 10 with the second probe 42, and the control unit 60 acquires the measurement results of these heights.

In the grinding step 1002, the grinding unit 20 grinds the workpiece 100, and the thickness calculation unit 61 calculates the thickness of the workpiece 100 from the difference between the change in the position (height) of the holding surface 13 and the change in the top surface position (height) of the workpiece 100. The judgment unit 62 judges whether the change in the thickness of the workpiece 100 over time matches or is within an acceptable range with the grinding speed for grinding the workpiece 100. If the judgment unit 62 judges that the change is "agree or within the acceptable range," the grinding of the workpiece 100 by the grinding unit 20 continues. If the judgment unit 62 judges that the change is "not agree or outside the acceptable range," the notification unit 50 notifies an error.

In the grinding step 1002, the control unit 60 detects the moment when the height measured by the first probe 41 and the second probe 42 changes from the pre-grinding origin position of the first probe 41 and the second probe 42 stored in advance as the timing when the grinding wheel 22 and the workpiece 100 start contacting each other, and if the state in which the judgment unit 62 judges that the heights do not match or are outside the acceptable range continues for a predetermined time or more after the timing when the grinding wheel 22 and the workpiece 100 start contacting each other, the notification unit 50 may be made to notify an error. By performing the grinding step 1002 in this manner, it is possible to prevent the phenomenon of the chuck table 10 sinking at the start of grinding from being erroneously reported as an error.

The grinding device 1 and grinding method according to the embodiment having the above configuration use the first probe 41 to measure the height of the holding surface 13 of the chuck table 10 holding the workpiece 100, and the second probe 42 to measure the height of the top surface of the workpiece 100 held on the holding surface 13 of the chuck table 10. The thickness of the workpiece 100 is calculated from the difference between these two heights, and whether the grinding of the workpiece 100 is normal or not is determined based on whether the change over time in the thickness of the workpiece 100 and the grinding speed at which the workpiece 100 is ground coincide or are within an acceptable range. This provides the effect of directly monitoring whether the workpiece 100 is being ground.

In addition, in the grinding device 1 and grinding method according to the embodiment, the control unit 60 pre-stores the origin positions of the first probe 41 and the second probe 42 before grinding, detects the moment when the heights measured by the first probe 41 and the second probe 42 change from their respective origin positions as the timing when the grinding wheel 22 and the workpiece 100 start contacting each other, and if the state in which the judgment unit 62 judges that the two do not match or are outside the acceptable range continues for a predetermined period of time or more after the timing when the grinding wheel 22 and the workpiece 100 start contacting each other, the notification unit 50 can be made to notify an error. Therefore, the grinding device 1 and grinding method according to the embodiment have the effect of preventing the phenomenon of the chuck table 10 sinking at the start of grinding from being erroneously reported as an error.

The present invention is not limited to the above embodiment. In other words, the present invention can be implemented in various modifications without departing from the gist of the invention.

REFERENCE SIGNS LIST 1 Grinding device 10 Chuck table 13 Holding surface 20, 20-1, 20-2 Grinding unit 21 Spindle 22 Grinding wheel 30, 30-1, 30-2 Grinding feed unit 40 Contact type thickness measuring unit 41 First probe 42 Second probe 60 Control unit 61 Thickness calculation unit 62 Determination unit 100 Workpiece

Claims (4)

A grinding device for grinding a plate-shaped workpiece, comprising:
a chuck table that holds the workpiece on a holding surface;
a grinding unit having a grinding wheel attached to a tip of a spindle and disposed opposite to a holding surface of the chuck table to grind a workpiece held on the chuck table;
a grinding feed unit that moves the grinding unit and the chuck table toward and away from each other;
a contact type thickness measuring unit including a first probe for measuring a position of the holding surface on the outer side of the workpiece, the holding surface holding the workpiece, and a second probe for measuring a position of an upper surface of the workpiece held on the holding surface;
A control unit for controlling each of the components,
The control unit
a thickness calculation unit that calculates a thickness of the workpiece from a difference between data measured by the first probe and data measured by the second probe;
a determination unit that determines whether or not the change in thickness of the workpiece calculated by the thickness calculation unit coincides with a grinding speed for grinding the workpiece or is within an allowable range,
The grinding device continues grinding if the results match or are within the tolerance range, and reports an error if the results are outside the tolerance range. The grinding device according to claim 1, wherein the control unit stores the origin positions of the first probe and the second probe before grinding, and determines the moment when the value changes from the origin position as the timing when the grinding wheel and the workpiece start contacting each other, and issues an error notification when the change in the thickness of the workpiece calculated by the thickness calculation unit over time does not match the grinding speed at which the workpiece is ground, or when the state outside the allowable range continues for a predetermined time or more from the timing when the contact starts. A grinding method for grinding a plate-shaped workpiece, comprising the steps of:
a holding step of holding the workpiece on a holding surface of a chuck table;
a grinding step in which a grinding unit including a spindle with a grinding wheel attached to its tip and the chuck table are brought closer to each other while rotating, and the workpiece is ground while measuring the thickness of the workpiece using a contact thickness measuring unit including a first probe for measuring the position of the holding surface outside the workpiece on the holding surface that holds the workpiece, and a second probe for measuring the position of the upper surface of the workpiece held on the holding surface,
The grinding step includes grinding the workpiece, calculating a thickness of the workpiece from a difference between a change in the position of the holding surface and a change in the position of the top surface of the workpiece, continuing grinding if the change in thickness of the workpiece over time coincides with the grinding speed for grinding the workpiece or is within an allowable range, and reporting an error if the change is outside the range. The grinding step stores the origin positions of the first probe and the second probe before grinding, respectively, and sets the moment when the value changes from the origin position as the timing when the grinding wheel and the workpiece start contacting each other, and issues an error notification when the change in the thickness of the workpiece calculated by the thickness calculation unit over time does not match the grinding speed at which the workpiece is ground, or when the state outside the allowable range continues for a predetermined time or more from the contact start timing. The grinding method according to claim 3.

Images