JP2021000711A - Method for processing workpiece - Google Patents

Abstract

To prevent excessive grinding of a workpiece and damage of a grinding device even when a function of a control unit stops.SOLUTION: There is provided grinding method for grinding a workpiece by a grinding device that includes a chuck table, a spindle for rotating a grinding wheel, a servo motor for moving the spindle, a servo driver for transmitting a signal to the servo motor, a control unit for controlling the servo driver and a thickness measurement unit for measuring a thickness of the workpiece, the method including: a grinding amount instructing step of subtracting a target thickness from a thickness of the workpiece and calculating a scheduled grinding amount, and instructing the scheduled grinding amount to the servo driver; and a grinding step of moving the spindle by the servo motor and grinding the workpiece, in which in the grinding step, when the spindle is moved by the target distance corresponding to the scheduled grinding amount, the servo driver ends the movement with the spindle.SELECTED DRAWING: Figure 4

Description

The present invention relates to a method for processing an workpiece such as a semiconductor wafer by grinding and thinning the workpiece.

The device chip mounted on the electronic device is formed, for example, by dividing a disk-shaped semiconductor wafer. When a plurality of scheduled division lines intersecting each other are set on the surface of the semiconductor wafer, devices such as ICs are formed in each region partitioned by the planned division lines, and the semiconductor wafer is divided along the planned division lines, the individual devices are formed. Chips can be made.

In recent years, the tendency of miniaturization of electronic devices has been remarkable, and the demand for miniaturization and thinning of device chips mounted on electronic devices has also increased. Therefore, in order to manufacture a thin device chip, the semiconductor wafer is ground by a grinding device and thinned to a predetermined thickness before the semiconductor wafer is divided.

The grinding device includes a chuck table capable of holding a workpiece and a grinding unit arranged above the chuck table. The grinding unit includes a spindle substantially along the vertical direction, a spindle motor connected to the upper end of the spindle, and a grinding wheel mounted on the lower end of the spindle. The grinding wheel includes grinding wheels arranged in an annular shape on the lower surface facing the upper surface of the chuck table.

The grinding device includes a grinding feed unit. The grinding feed unit includes, for example, a servomotor that relatively moves a spindle and a chuck table in directions that approach or separate from each other, and a servodriver that sends a signal to the servomotor.

When grinding a work piece with a grinding device, the work piece is fixed on a chuck table, the chuck table is rotated around an axis perpendicular to the upper surface of the chuck table, and a grinding wheel is used. Is rotated in the same way. Then, the spindle and the chuck table are relatively moved in the directions of approaching or separating from each other. Then, the grinding wheel moving on the annular track comes into contact with the workpiece, and the workpiece is ground (see, for example, Patent Document 1).

Further, the grinding apparatus includes a thickness measuring unit for measuring the thickness of the workpiece being ground in the vicinity of the chuck table. When grinding a workpiece, the control unit of the grinding device issues a command to the servo driver to start the relative movement between the spindle and the chuck table, and the thickness measuring unit monitors the thickness of the workpiece while grinding. Have the unit grind the workpiece. Then, when the workpiece reaches a predetermined target thickness, a command is issued to the servo driver to end the relative movement.

Japanese Unexamined Patent Publication No. 2003-209080

The control unit of the grinding device controls the operation of all the units and measuring instruments constituting the grinding device, and continuously processes various kinds of information. Therefore, for example, the control unit may stop functioning due to an excessive processing load applied to the control unit after the grinding of the workpiece is started.

The stopped control unit cannot command the servo driver to end the relative movement of the spindle and the chuck table when the workpiece reaches a predetermined target thickness. If the relative movement cannot be completed, not only the workpiece will be thinner than the target thickness, but also the workpiece will disappear due to grinding, and the grinding wheel may come into contact with the chuck table, causing serious damage to the grinding device. is there.

The present invention has been made in view of the above problems, and an object of the present invention is to excessively grind the workpiece even if the control unit of the grinding apparatus stops functioning during grinding of the workpiece. It is to provide a processing method of a workpiece which is not afraid and does not cause damage to a grinding apparatus.

According to one aspect of the present invention, a chuck table having a holding surface for holding an workpiece and rotating around an axis intersecting the holding surface, and a disk-shaped grinding wheel including a grinding wheel are mounted on the grinding wheel. Sends a signal to the servomotor of the grinding feed unit and the grinding feed unit having a spindle for rotating the chuck table and the spindle in a direction relatively moving toward or away from each other. A grinding method for grinding the work piece by a grinding device including a servo driver and a control unit for controlling the servo driver, wherein the work piece is held on the holding surface of the chuck table. , The value obtained by subtracting the target thickness of the work piece registered in the control unit in advance from the thickness of the work piece is calculated as the planned grinding amount, and the calculated planned grinding amount is calculated by the control unit. A direction in which the chuck table and the spindle are brought closer to each other by the servo motor of the grinding feed unit while rotating the chuck table and the grinding wheel, respectively, and the grinding amount command step commanding the servo driver of the grinding feed unit. A grinding step is provided in which the workpiece held on the chuck table is ground by the grinding wheel, and in the grinding step, the servo driver has the chuck table and the spindle. Provided is a method for processing a workpiece, characterized in that the relative movement between the chuck table and the spindle is terminated when the target distance corresponding to the planned grinding amount is relatively moved.

Preferably, the grinding device further comprises a thickness measuring unit for measuring the thickness of the workpiece held by the holding surface of the chuck table, and in the grinding amount command step, the thickness of the workpiece is measured. The thickness of the work piece is repeatedly measured by the thickness measuring unit until the target thickness is reached, and the planned grinding is performed by subtracting the target thickness from the measured thickness of the work piece. The amount is updated, and the updated scheduled grinding amount is repeatedly commanded by the control unit to the servo driver of the grinding feed unit, and in the grinding step, the servo driver has the chuck table and the spindle as the target. Each time the control unit commands the updated scheduled grinding amount before moving relative to the distance, the target distance is updated based on the updated scheduled grinding amount.

In the method of processing a workpiece according to one aspect of the present invention, the control unit does not command the servo driver to start and stop the operation. When grinding is performed, the value obtained by subtracting the target thickness of the workpiece from the thickness of the workpiece is calculated as the planned grinding amount, and the calculated planned grinding amount is instructed to the servo driver. Then, the servo driver ends the relative movement between the chuck table and the spindle when the chuck table and the spindle move relative to each other by a target distance corresponding to the planned grinding amount.

In this case, even if the control unit stops functioning while grinding the workpiece, the commanded planned grinding amount remains in the servo driver. Then, the servo driver moves the chuck table and the spindle by a target distance corresponding to the planned grinding amount, and then ends the relative movement. Therefore, even if the control unit stops functioning while grinding the workpiece, the workpiece will not be excessively ground or the grinding device will not be damaged.

Therefore, according to the present invention, even if the control unit of the grinding apparatus stops functioning during grinding of the workpiece, there is no possibility that the workpiece is excessively ground and the grinding apparatus is not damaged. The method is provided.

It is a perspective view which shows typically the grinding apparatus. It is a perspective view which shows typically the grinding step. It is sectional drawing which shows typically the grinding step. FIG. 4A is a flowchart showing the flow of each step carried out by the machining method of the workpiece according to the embodiment, and FIG. 4B is a flowchart showing the flow of the grinding amount command step. FIG. 4C is a flowchart showing the flow of the grinding step.

An embodiment of the present invention will be described with reference to the drawings. In the method for processing a work piece according to the present embodiment, a work piece such as a substantially disk-shaped semiconductor wafer is ground and thinned to a predetermined thickness. First, the workpiece will be described. FIG. 1 shows a perspective view schematically showing the workpiece 1.

The workpiece is a wafer made of, for example, Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductor material. Alternatively, it is a substantially disk-shaped substrate made of a material such as sapphire, glass, or quartz. The glass is, for example, alkaline glass, non-alkali glass, soda-lime glass, lead glass, borosilicate glass, quartz glass and the like.

A plurality of devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are formed on the surface 1a of the workpiece 1. Then, by dividing the workpiece 1 for each device, individual device chips can be formed. If the workpiece 1 is ground and thinned before the workpiece 1 is divided, the workpiece 1 can be divided thereafter to form a thin device chip. However, the device may not be formed on the surface 1a of the workpiece 1 to be ground.

The method for processing a workpiece according to the present embodiment is carried out by a grinding apparatus including a grinding unit. Hereinafter, the grinding apparatus 2 will be described with reference to FIG. FIG. 1 includes a perspective view schematically showing the grinding device 2.

In the grinding device 2, the back surface 1b is ground with the back surface 1b side of the workpiece 1 exposed upward. When a device is formed in advance on the surface 1a of the workpiece 1, a tape-shaped protective member is formed on the surface 1a side of the workpiece 1 in order to protect the surface 1a side when grinding the workpiece 1. 3 is pasted. Hereinafter, the case where the protective member 3 is attached to the workpiece 1 will be described as an example, but the present embodiment is not limited to this.

The protective member 3 includes, for example, a base material layer and a glue layer formed on the base material layer. When grinding the back surface 1b side of the workpiece 1, the surface 1a side of the workpiece 1 is supported by the chuck table 8 described later. At this time, if the surface 1a and the holding surface 8a of the chuck table 8 are in direct contact with each other, the device formed on the surface 1a may be damaged when the workpiece 1 is ground. Therefore, the protective member 3 is attached to the surface 1a side of the workpiece 1.

The workpiece 1 is, for example, accommodated in a cassette 28a capable of accommodating a plurality of workpieces 1 and transported, and then carried into the grinding apparatus 2. The grinding device 2 includes a base 4 that supports each component. Cassette mounting bases 26a and 26b are fixed to the front end of the base 4. For example, a cassette 28a containing the workpiece 1 before grinding is placed on the cassette mounting table 26a, and a cassette 28b for accommodating the workpiece 1 after grinding is placed on the cassette mounting table 26b. Be placed.

The transfer robot 30 is installed at a position adjacent to the cassette mounting bases 26a and 26b on the base 4. The transfer robot 30 carries out the workpiece 1 from the cassette 28a mounted on the cassette mounting table 26a, and the workpiece 1 is placed on a positioning table 32 provided at a position adjacent to the transfer robot 30 on the base 4. To carry.

The positioning table 32 has a plurality of positioning pins arranged in an annular shape. When the workpiece 1 is placed in the central mounting area, the positioning table 32 moves the positioning pins inward in the radial direction in conjunction with each other to move the workpiece 1 to a predetermined position. Position.

A loading arm 34 and an unloading arm 36 are provided at positions adjacent to the positioning table 32 on the upper surface of the base 4. The workpiece 1 positioned at the position determined by the positioning table 32 is conveyed by the loading arm 34.

A disk-shaped turntable 6 is rotatably provided on the central upper surface of the base 4 in a horizontal plane. On the upper surface of the turntable 6, for example, three chuck tables 8 separated from each other by 120 degrees in the circumferential direction are provided. By rotating the turntable 6, each chuck table 8 can be moved.

Each chuck table 8 has a suction path (not shown) at one end connected to a suction source (not shown), and the other end of the suction path is connected to a holding surface 8a on the chuck table 8. .. FIG. 3 includes a cross-sectional view schematically showing the chuck table 8. The holding surface 8a is composed of, for example, the upper surface of the porous member 8b. The chuck table 8 operates the suction source when the object to be held is placed on the holding surface 8a, and causes the generated negative pressure to act on the object to be held through the porous member 8b, thereby causing the object to be held. Can hold by suction.

The chuck table 8 is fixed on a table support 8d provided on the upper surface of the turntable 6. A table rotation motor 8e fixed on the turntable 6 is connected to the lower surface of the table support 8d via a spindle. When the table rotation motor 8e is operated, the chuck table 8 fixed to the table support base 8d rotates around the table rotation shaft 8c that intersects the holding surface 8a.

The loading / unloading of the workpiece 1 to / from the chuck table 8 is carried out in the loading / unloading area 6a of the turntable 6 shown in FIG. In the carry-in / carry-out area 6a, the work piece 1 can be carried into the chuck table 8 by the loading arm 34, and the work piece 1 can be carried out from the chuck table 8 by the unloading arm 36.

When grinding the work piece 1, the work piece 1 is carried into the chuck table 8 located in the carry-in / carry-out area 6a by the loading arm 34, and then the turntable 6 is rotated to bring the chuck table 8 into place. It is moved to the next rough grinding region 6b.

On the outside of the turntable 6 on the rear upper surface of the base 4, a first grinding unit 10a for rough grinding the back surface 1b side of the workpiece 1 held by the chuck table 8 located in the rough grinding region 6b is It is arranged. After the work piece 1 is roughly ground by the first grinding unit 10a, the turntable 6 is rotated to move the chuck table 8 to the finish grinding area 6c adjacent to the rough grinding area 6b.

On the outside of the turntable 6 on the rear upper surface of the base 4, a second grinding unit 10b for finish grinding the back surface 1b side of the workpiece 1 held by the chuck table 8 located in the finish grinding area 6c is It is arranged. In the second grinding unit 10b, the workpiece 1 is finish-ground. After the finish grinding of the workpiece 1 is performed by the second grinding unit 10b, the turntable 6 is rotated to return the chuck table 8 to the loading / unloading region 6a, and the workpiece 1 is returned by the unloading arm 36. Is carried out from the chuck table 8.

A spinner cleaning device 38 for cleaning and drying the ground workpiece 1 is disposed in the vicinity of the unloading arm 36 on the upper surface of the base 4 and the transfer robot 30. Then, the workpiece 1 cleaned and dried by the spinner cleaning device 38 is conveyed from the spinner cleaning device 38 by the transfer robot 30 and housed in the cassette 28b mounted on the cassette mounting table 26b.

The grinding device 2 will be further described with reference to FIGS. 1 and 3. A column 22a is erected at the rear of the base 4. A grinding feed unit 24a that movably supports the first grinding unit 10a along the vertical direction is arranged on the front surface of the column 22a. The grinding feed unit 24a includes a spindle 50 extending along the vertical direction, a servomotor 48 connected to the upper end of the spindle 50, and a servodriver 46 connected to the servomotor 48.

The servo driver 46 sends a signal to the servo motor 48 to control the servo motor 48. The servo driver 46 is, for example, a PC (Personal Computer) or a microcomputer equipped with a CPU (Central Processing Unit), a main memory, a storage device, and the like. Software that realizes the function of the servo driver 46 is stored in the storage device. The servo driver 46 functions as a concrete means in which the software and the hardware resources cooperate by operating the CPU or the like according to the software. Further, the servo driver 46 may be composed of a plurality of modules that integrally realize each function.

A nut portion 52 arranged on the back surface of the elevating plate 54 is screwed onto the spindle 50. When the servo driver 46 commands the servo motor 48 to operate the servo motor 48, the spindle 50 rotates and the elevating plate 54 including the nut portion 52 moves up and down. A first grinding unit 10a is fixed to the front surface of the elevating plate 54.

The first grinding unit 10a includes a spindle 14a extending along the vertical direction and a spindle motor 12a connected to the upper end of the spindle 14a. A disk-shaped wheel mount 16a is arranged at the lower end of the spindle 14a. A disk-shaped grinding wheel 18a is mounted on the lower surface of the wheel mount 16a. A plurality of grinding wheels 20a arranged in an annular shape are fixed to the lower surface of the grinding wheel 18a.

When the spindle motor 12a is operated, the grinding wheel 18a rotates around the wheel rotation shaft 12c perpendicular to the lower surface of the grinding wheel 18a, that is, in the circumferential direction.

When grinding the workpiece 1 in the rough grinding region 6b, first, the grinding wheel 18a is rotated around the wheel rotation shaft 12c to move the grinding wheel 20a along the annular trajectory, and the chuck table 8 is moved to the table. Rotate around the rotating shaft 8c. Then, when the grinding feed unit 24a is operated to lower the first grinding unit 10a and the grinding wheel 20a is brought into contact with the back surface 1b of the workpiece 1 held on the chuck table 8, the workpiece 1 is brought into contact with the workpiece 1. It is ground from the back surface 1b side.

The grinding wheel 20a is formed by, for example, abrasive grains made of diamond or the like dispersed in a binder. Abrasive grains are appropriately exposed from the binder on the contact surface of the grinding wheel 20a in contact with the workpiece 1, and the exposed abrasive grains come into contact with the workpiece 1 to grind the workpiece 1. ..

Further, on the front surface of the column 22b, a grinding feed unit 24b that supports the second grinding unit 10b so as to be movable along the vertical direction is arranged. The grinding feed unit 24b is configured in the same manner as the grinding feed unit 24a. Further, the second grinding unit 10b includes a spindle 14b extending in the vertical direction and a spindle motor 12b connected to the upper end of the spindle 14b, similarly to the first grinding unit 10a.

A disk-shaped wheel mount 16b is disposed at the lower end of the spindle 14b, and a grinding wheel 18b is fixed to the lower surface of the wheel mount 16b. A plurality of grinding wheels 20b arranged in an annular shape are mounted on the lower surface of the grinding wheel 18b. Also in the second grinding unit 10b, when the spindle motor 12b is operated, the grinding wheel 18b rotates around a wheel rotation axis perpendicular to the lower surface.

When grinding the workpiece 1 in the finish grinding region 6c, the grinding wheel 18b is rotated to move the grinding wheel 20b along the annular trajectory, and the chuck table 8 is rotated. Then, when the grinding feed unit 24b is operated to lower the second grinding unit 10b and the grinding wheel 20b is brought into contact with the back surface 1b of the workpiece 1 held on the chuck table 8, the workpiece 1 is brought into contact with the workpiece 1. It is ground from the back surface 1b side.

In the grinding of the workpiece 1 using the first grinding unit 10a, the grinding feed by the grinding feed unit 24a is performed at a relatively high speed to roughly grind the workpiece 1. In the rough grinding by the first grinding unit 10a, most of the thickness of the workpiece 1 which is ground and removed by the grinding device 2 is efficiently removed.

In the grinding of the workpiece 1 using the second grinding unit 10b, the grinding feed by the grinding feed unit 24b is performed at a relatively low speed to finish grind the workpiece 1. In the finish grinding by the second grinding unit 10b, the workpiece 1 is ground to the planned finish thickness with high accuracy.

Although the case where the grinding feed units 24a and 24b including the servomotor 48, the spindle 50, the nut portion 52 and the like function as an elevating mechanism for raising and lowering the grinding units 10a and 10b has been described, the present embodiment is not limited to this. For example, the grinding feed units 24a and 24b may raise and lower the chuck table 8 instead of the grinding units 10a and 10b. That is, the grinding feed units 24a and 24b have a function of relatively moving the chuck table 8 and the spindles 14a and 14b in the directions of approaching or separating from each other.

A first thickness measuring unit 40 for measuring the thickness of the workpiece 1 roughly ground by the first grinding unit 10a is arranged in the vicinity of the rough grinding region 6b on the upper surface of the base 4. There is. The first thickness measuring unit 40 is, for example, a contact type thickness measuring unit. However, the first thickness measuring unit 40 is not limited to the contact type thickness measuring unit, and may be another type of thickness measuring instrument.

As shown in FIGS. 2 and 3, the first thickness measuring unit 40 has a first probe 40a that contacts the back surface 1b of the workpiece 1 and measures the height of the back surface 1b, and a chuck table 8. A second probe 40b that comes into contact with the holding surface 8a and measures the height of the holding surface 8a is provided. Further, a post 40c for supporting the first probe 40a and the second probe 40b is provided. The first thickness measuring unit 40 can calculate the thickness of the workpiece 1 from the difference between the height of the back surface 1b of the workpiece 1 and the height of the holding surface 8a of the chuck table 8.

In the vicinity of the finish grinding region 6c on the upper surface of the base 4, a non-contact type second thickness measuring unit 42 for measuring the thickness of the workpiece 1 to be finish ground by the second grinding unit 10b is provided. It is arranged. The second thickness measuring unit 42 measures the height of the back surface 1b of the workpiece 1 by, for example, irradiating the back surface 1b of the workpiece 1 with a laser beam and detecting the reflected laser beam. Laser thickness measurement unit (spectral interference laser displacement meter). However, the second thickness measuring unit 42 is not limited to this.

The contact mode between the grinding wheels 20a and 20b at the time of grinding the workpiece 1 and the workpiece 1 will be described. As shown in FIG. 3, in the grinding apparatus 2, the holding surface 8a of the chuck table 8 has a conical shape with an extremely small inclination, and the annular trajectory on which the grinding wheels 20a and 20b move is the holding surface 8a of the chuck table 8. It is set to pass above the center. When grinding the workpiece 1, the grinding wheels 20a and 20b come into contact with the workpiece 1 in an arcuate region extending from the center of the holding surface 8a of the chuck table 8 to the outer peripheral portion and overlapping the annular track.

When grinding the workpiece 1, the grinding wheels 18a and 18b rotate around the wheel rotation shaft 12c, and the chuck table 8 rotates around the table rotation shaft 8c that intersects the holding surface 8a of the chuck table 8. .. Therefore, various parts of the back surface 1b of the workpiece 1 approach the arcuate region one after another, and the entire back surface 1b of the workpiece 1 is ground.

The grinding device 2 further includes a control unit 44 that controls each component of the grinding device 2. The control unit 44 controls the turntable 6, the chuck table 8, the grinding feed units 24a and 24b, the grinding units 10a and 10b, the servo driver 46, the thickness measuring units 40 and 42, and the like. Further, the control unit 44 controls the transfer robot 30, the positioning table 32, the loading arm 34, the unloading arm 36, the spinner cleaning device 38, and the like.

The control unit 44 is composed of a processing device such as a CPU and a computer including a storage device such as a flash memory. By operating the processing device according to software such as a program stored in the storage device, the control unit functions as a concrete means in which the software and the processing device (hardware resource) cooperate with each other.

When grinding the workpiece 1 is performed, the control unit 44 rotates the chuck table 8 and the grinding units 10a and 10b, respectively. Conventionally, the control unit 44 commands the servo driver 46 to operate the servo motor 48 to move the chuck table 8 and the spindles 14a and 14b included in the grinding units 10a and 10b relative to each other in the direction of approaching each other. To start.

Conventionally, the target thickness of the workpiece 1 is registered in advance in the control unit 44, and the control unit 44 controls the thickness measuring units 40 and 42 to grind the thickness of the workpiece 1. Measure. Then, when the thickness of the workpiece 1 reaches the target thickness, the control unit 44 commands the servo driver 46 to stop the servo motor 48. Then, the grinding of the workpiece 1 is completed.

Here, as described above, the control unit 44 controls the operation of each unit and the measuring instrument constituting the grinding device 2, and continuously processes various kinds of information. Therefore, for example, the control unit 44 may stop functioning due to an excessive processing load being applied to the control unit 44 after the grinding of the workpiece 1 is started.

The stopped control unit 44 cannot instruct the servo driver 46 to end the relative movement between the chuck table 8 and the spindles 14a and 14b when the workpiece 1 reaches a predetermined target thickness. If the chuck table 8 and the spindles 14a and 14b cannot be stopped, not only the workpiece 1 becomes thinner than the target thickness, but also the workpiece 1 disappears by grinding and the grinding wheels 20a and 20b come into contact with the chuck table 8. As a result, the grinding device 2 may be seriously damaged.

Therefore, in the grinding apparatus 2 in which the method for processing the workpiece according to the present embodiment is implemented, the servo driver 46 spindles when the grinding feed proceeds to the extent that the workpiece 1 is assumed to have reached the target thickness. Stop the grinding feed of 14a, 14b, etc. In this case, even if the control unit 44 cannot issue a command to the servo driver 46 to stop the servo motor 48, the servo driver 46 stops the servo motor 48, so that the workpiece 1 is not excessively ground.

This will be described in detail. The control unit 44 calculates a value obtained by subtracting the target thickness of the workpiece 1 registered in the control unit 44 from the thickness of the workpiece 1 as the planned grinding amount. The control unit 44 commands the calculated planned grinding amount to the servo drivers 46 of the grinding feed units 24a and 24b. Here, the thickness of the workpiece 1 may be registered in the control unit 44 in advance, or may be measured by the thickness measuring units 40 and 42 before grinding the workpiece 1.

When the control unit 44 commands the planned grinding amount, the servo driver 46 starts the relative movement of the chuck table 8 and the spindles 14a and 14b in the directions close to each other. Then, when both move relative to each other by a target distance corresponding to the planned grinding amount, the relative movement of the chuck table 8 and the spindles 14a and 14b is completed.

In this case, the servo driver 46 can control the servo motor 48 even when the control unit 44 stops functioning and the command to the servo driver 46 is no longer sent from the control unit 44. That is, the servo driver 46 can stop the grinding feed when the workpiece 1 reaches the target thickness.

At this time, it is conceivable that the worn state of the grinding wheels 20a and 20b is not sufficiently reflected in the target distance, but at least the workpiece 1 is not excessively ground and the grinding device 2 is damaged. It does not occur.

Further, the control unit 44 has a function of repeatedly measuring the thickness of the workpiece 1 with the thickness measuring units 40 and 42 until the thickness of the workpiece 1 reaches the target thickness of the workpiece 1. You may. Then, the control unit 44 calculates a value obtained by subtracting the target thickness from the measured thickness of the workpiece 1 as a planned grinding amount, and repeatedly commands the servo driver 46 to the calculated planned grinding amount. Good. The servo driver 46 may update the target distance based on the new scheduled grinding amount commanded each time the scheduled grinding amount is repeatedly commanded by the control unit 44.

In this case, the thickness of the workpiece 1 being ground is repeatedly monitored, and the target distance is corrected according to the actual thickness of the workpiece 1. Then, since the worn state of the grinding wheels 20a and 20b is reflected in the target distance, the thickness of the workpiece 1 approaches the target thickness more precisely when the grinding of the workpiece 1 is completed.

Hereinafter, a method for processing the workpiece according to the present embodiment implemented by the grinding device 2 will be described. In the processing method, the workpiece 1 is ground by the grinding device 2 to be thinned. FIG. 4A is a flowchart showing a flow of each step carried out by the processing method of the workpiece according to the present embodiment.

In the processing method, the workpiece 1 is ground in a holding step S1 for holding the workpiece 1 on the holding surface 8a of the chuck table 8, a grinding amount command step S2 for repeatedly instructing the servo driver 46 to perform a planned grinding amount, and a workpiece 1. Grinding steps S3 and are carried out. Each step will be described in detail below.

In the holding step S1, for example, as shown in FIG. 1, the workpiece 1 is housed in the cassette 28a with the protective member 3 attached to the surface 1a side, and the cassette 28a is carried into the grinding device 2. .. Then, for example, the transfer robot 30 is used to carry out the workpiece 1 housed in the cassette 28a and transfer it to the positioning table 32. Then, after the position of the workpiece 1 is positioned at a predetermined position by the positioning table 32, the workpiece 1 is conveyed by the loading arm 34 on the chuck table 8 positioned in the carry-in / carry-out region 6a.

Here, the front surface 1a side of the workpiece 1 is directed downward so that the back surface 1b side, which is the surface to be ground of the workpiece 1, is exposed upward. Then, the workpiece 1 is placed on the holding surface 8a of the chuck table 8 and the suction source of the chuck table 8 is operated to suck and hold the workpiece 1 on the chuck table 8.

In the processing method of the workpiece according to the present embodiment, the grinding amount command step S2 and the grinding step S3 are next carried out. FIG. 4B is a flowchart schematically showing the flow carried out in the grinding amount command step S2, and FIG. 4C is a flowchart schematically showing the flow carried out in the grinding step S3. Further, FIG. 2 is a perspective view schematically showing the grinding amount command step S2 and the grinding step S3, and FIG. 3 is a cross-sectional view schematically showing the grinding amount command step S2 and the grinding step S3.

In the grinding step S3, the work piece 1 is roughly ground by using the first grinding unit 10a in the rough grinding region 6b. Alternatively, in the grinding step S3, the rough-ground workpiece 1 is finish-ground in the finish-grinding region 6c using the second grinding unit 10b. Hereinafter, a case where the workpiece 1 is roughly ground by using the first grinding unit 10a in the rough grinding region 6b will be described as an example, but the description will be omitted because the finish grinding can be performed in the same manner.

Further, the grinding step S3 is started while the grinding amount command step S2 is in progress, and then proceeds together with the grinding amount command step S2. Here, the grinding amount command step S2 and the grinding step S3 will be described individually.

The target thickness of the workpiece 1 when the rough grinding is completed is registered in the control unit 44. In the grinding amount command step S2, the thickness of the workpiece 1 is measured by the first thickness measuring unit 40 (S21). Then, the thickness of the workpiece 1 is compared with the target thickness to determine whether or not the thickness of the workpiece 1 has reached the target thickness (S22). Normally, the thickness of the workpiece 1 does not reach the target thickness immediately after the grinding amount command step S2 is started.

When the thickness of the workpiece 1 does not reach the target thickness, the value obtained by subtracting the target thickness from the measured thickness of the workpiece 1 is calculated as the planned grinding amount (S23). After that, the calculated planned grinding amount is commanded by the control unit 44 to the servo driver 46 of the grinding feed unit 24a (S24).

When the planned grinding amount is commanded to the servo driver 46 by the control unit 44, the grinding step S3 is started as described later, and the workpiece 1 is ground and begins to be thinned. In the grinding amount command step S2, the thickness of the workpiece 1 is periodically measured by the first thickness measuring unit 40 while the workpiece 1 is being thinned (S21). Then, it is determined again whether or not the thickness of the workpiece 1 has reached the target thickness (S22).

As a result of the determination, when it is determined that the thickness of the workpiece 1 has not reached the target thickness, the target thickness of the workpiece 1 is subtracted from the remeasured thickness of the workpiece 1. The value is newly calculated as the planned grinding amount (S23). Normally, while the grinding is in progress, the workpiece 1 is gradually thinned, and the planned grinding amount is reduced by the amount of the thinned workpiece 1. Then, the newly calculated planned grinding amount is commanded by the control unit 44 to the servo driver 46 of the grinding feed unit 24a (S24).

On the other hand, when grinding progresses and it is determined that the thickness of the workpiece 1 has reached the target thickness (S22), the control unit 44 does not newly instruct the servo driver 46. Then, the grinding amount command step S2 is completed.

That is, in the grinding amount command step S2, the workpiece 1 is used in the first thickness measuring unit 40 until the thickness of the workpiece 1 reaches the target thickness of the workpiece 1 registered in advance in the control unit 44. Repeatedly measure the thickness of. Then, a value obtained by subtracting the target thickness from the measured thickness of the workpiece 1 is calculated as a planned grinding amount, and the calculated planned grinding amount is repeatedly applied to the servo driver 46 of the grinding feed unit 24a by the control unit 44. Command.

Next, the grinding step S3 will be described. The grinding step S3 is started while the grinding amount command step S2 is in progress. In the grinding step S3, first, the grinding wheel 18a is rotated around the wheel rotation shaft 12c while rotating the chuck table 8 around the table rotation shaft 8c.

Then, when the servo driver 46 is instructed by the control unit 44 about the planned grinding amount (S31), the servo motor 48 of the grinding feed unit 24a moves the chuck table 8 and the spindle 14a relative to each other in the direction of approaching each other. Start (S32). For example, the servo driver 46 starts the operation of the servo motor 48 and lowers the spindle 14a of the first grinding unit 10a at a predetermined speed.

The servo driver 46 feedback-controls the servo motor 48 so that a predetermined operation is performed while monitoring the operating status of the servo motor 48. Then, when the grinding wheel 20a moving on the annular track comes into contact with the back surface 1b of the workpiece 1 held by the holding surface 8a of the chuck table 8, the workpiece 1 is ground by the grinding wheel 20a and the workpiece 1 is moved. It begins to be diluted.

The servo driver 46 controls the servo motor 48 aiming at a state in which the chuck table 8 and the spindle 14a of the first grinding unit 10a are brought closer to each other by a target distance corresponding to the planned grinding amount. Then, it is determined whether or not the chuck table 8 and the spindle 14a have relatively moved by the target distance (S33). Normally, immediately after the start of the grinding step S3, the relative moving distance between the chuck table 8 and the spindle 14a does not reach the target distance.

Then, when it is determined that the chuck table 8 and the spindle 14a are not relatively moved by the target distance, it is next determined whether or not the target distance needs to be updated. That is, when a new scheduled grinding amount is commanded from the control unit 44 to the servo driver 46 as a result of the progress of the grinding amount command step S2 (S34), the servo driver 46 targets based on the new scheduled grinding amount. Update the distance (S35).

Further, when a new scheduled grinding amount is not commanded from the control unit 44 to the servo driver 46 (S34), the target distance is not updated and is based on the latest target distance registered in the servo driver 46 so far. Grinding step S3 is continued.

In the grinding step S3, whether or not the moving distance between the chuck table 8 and the spindle 14a has reached the target distance is periodically and repeatedly determined regardless of whether the target distance is updated or not (S33). .. When the moving distance has not reached the target distance and the servo driver 46 is newly instructed to perform the planned grinding amount (S34), the target distance is further based on the new planned grinding amount. Is updated (S35).

That is, the servo driver 46 is newly calculated each time the control unit 44 commands a newly calculated planned grinding amount until the chuck table 8 and the spindle 14a move relative to each other by the target distance. The target distance is updated based on the planned grinding amount.

Then, when the moving distance between the chuck table 8 and the spindle 14a has reached the target distance (S33), the servo driver 46 stops the servomotor 48, and the chuck table 8 and the spindle 14a The relative movement is completed (S36). In the processing method of the workpiece according to the present embodiment, the grinding amount command step S2 and the grinding step S3 are performed to grind the workpiece 1 held on the chuck table 8 by the originally planned grinding amount. And set the target thickness.

For example, when the grinding of the workpiece 1 is advanced, the grinding wheel 20a is consumed, and the thickness of the workpiece 1 is larger than the relative moving distance between the chuck table 8 and the spindle 14a. The amount of reduction may be small. In this case, if the target distance is not updated, the thickness of the workpiece 1 does not always reach the target thickness registered in the control unit 44 when the grinding step S3 is completed.

In the processing method of the workpiece according to the present embodiment, the thickness of the workpiece 1 is repeatedly measured, and the grinding amount required for the workpiece 1 to reach the target thickness is calculated as the planned grinding amount. to continue. At this time, since the progress of grinding and the consumption state of the grinding wheel 20a are reflected in the planned grinding amount, the workpiece 1 is ground by the grinding wheel 20a until the thickness reaches the target thickness.

According to the work piece processing method according to the present embodiment described above, the work piece 1 has a substantially target thickness without damaging the grinding device 2 even when the control unit 44 stops functioning. Grinded to. One of the reasons for this is that the grinding amount command step S2 is realized mainly by the function of the control unit 44, while the grinding step S3 is realized mainly by the function of the servo driver 46. Next, a case where the control unit 44 stops functioning while the method for processing the workpiece according to the present embodiment is being implemented will be described.

The function stop of the control unit 44 means a state in which the function of the control unit 44 is stopped due to some abnormal situation, and information processing and transmission of commands cannot be performed. Conventionally, the control unit 44 has instructed the servo driver 46 to stop the servo motor 48 when the thickness of the workpiece 1 reaches the target thickness, but when the control unit 44 has stopped functioning, The control unit 44 cannot command the servo driver 46 to stop.

In the processing method of the workpiece according to the present embodiment, when the control unit 44 stops functioning while the grinding amount command step S2 and the grinding step S3 are in progress after the holding step S1 is performed, first, the grinding amount command step S2 cannot continue.

That is, the stopped control unit 44 cannot measure the thickness of the workpiece 1 using the first thickness measuring unit 40 (S21), and the thickness of the workpiece 1 is the target thickness. It cannot be determined whether or not it has reached (S22). Then, the planned grinding amount cannot be calculated (S23), and the planned grinding amount cannot be commanded to the servo driver 46 (S24).

In this case, in the grinding step S3, the planned grinding amount is not newly commanded from the control unit 44 (S34), and the target distance is not updated (S35). That is, when the control unit 44 has stopped functioning, in the grinding step S3, it is repeatedly determined whether the chuck table 8 and the spindle 14a have moved relative to each other by the target distance (S33).

Then, when the chuck table 8 and the spindle 14a move relative to each other by the target distance, the servo driver 46 stops the relative movement of the chuck table 8 and the spindle 14a (S36). Therefore, in the processing method of the workpiece according to the present embodiment, even if the control unit 44 stops functioning, the grinding step S3 ends normally.

In this case, since the target distance is not updated, the thickness of the work piece 1 ground due to the influence of wear of the grinding wheel 20a may not reach the target thickness. However, it can be said that the loss is extremely small as compared with the case where the workpiece 1 is excessively ground as in the conventional case. No physical damage is caused to the grinding device 2, and if the work piece 1 is ground again as necessary after the control unit 44 is restored, the work piece 1 having a target thickness can be obtained. Because. However, the work piece 1 may not be reground.

As described above, in the processing method of the workpiece according to the present embodiment, the grinding amount command step S2 may be terminated because the control unit 44 stops functioning. The method for processing the workpiece according to the present embodiment not only has an effect that the workpiece 1 is not lost when the control unit 44 stops functioning, but also when the control unit 44 does not stop functioning. Is also profitable.

For example, according to the processing method of the workpiece according to the present embodiment, even if the control unit 44 stops functioning, the chuck table 8 may be ground by the grinding wheels 20a and 20b, and the grinding device 2 may be damaged. Absent. This means that even if the control unit 44 stops functioning, the time required for restoration of the grinding device 2 can be shortened, and the cost required for restoration can be reduced.

Therefore, since the stop time of the grinding device 2 can be shortened, the machining efficiency when a plurality of workpieces 1 are machined one after another by the grinding device 2 is increased, and the number of workpieces 1 that can be machined per hour is increased. Further, since the workpiece 1 is not lost due to excessive grinding and it is not necessary to compensate for the loss, the processing cost can be reduced. That is, the machining efficiency of the workpiece 1 to be machined while the control unit 44 is not stopped has also increased.

That is, the processing method of the workpiece according to the present embodiment creates a situation in which the workpiece 1 is not lost and the grinding apparatus 2 is not damaged even if the control unit 44 is stopped in function. It is meaningful to process the workpiece 1 with. Therefore, the method for processing the workpiece according to the present embodiment does not need to stop the function of the control unit 44, and is not limited to the case where the control unit 44 stops functioning.

As described above, in the processing method of the workpiece according to the present embodiment, even if the control unit 44 of the grinding device 2 stops functioning during grinding of the workpiece 1, the workpiece 1 is excessively ground. There is no risk of damage to the grinding device 2.

The present invention is not limited to the description of the above embodiment, and can be implemented with various modifications. For example, in the above embodiment, the case where the workpiece 1 is ground by the first grinding unit 10a in the rough grinding region 6b has been described in detail, but one aspect of the present invention is not limited to this. That is, in one aspect of the present invention, the workpiece 1 may be ground by the second grinding unit 10b in the finish grinding region 6c.

Further, although the case where the grinding device 2 includes two grinding units of the first grinding unit 10a and the second grinding unit 10b has been described as an example, one aspect of the present invention is not limited to this. That is, the method for grinding a workpiece according to one aspect of the present invention may be carried out by a grinding device including one grinding unit, or may be carried out by a grinding device including three or more grinding units.

Further, in the above embodiment, the case where the control unit 44 of the grinding device 2 stops functioning has been described as an example, but one aspect of the present invention is also effective when the grinding device 2 does not operate normally due to other factors. .. For example, when an abnormality occurs in the thickness measuring units 40 and 42 during grinding of the workpiece 1 and the thickness of the workpiece 1 cannot be measured, or when a command is transmitted from the control unit 44 to the servo driver 46. The same effect is obtained when the wiring that serves as a route is cut.

Further, in the above embodiment, in the grinding amount command step S2, the thickness of the workpiece 1 is repeatedly measured, the planned grinding amount is updated, and the control unit 44 repeatedly commands the servo driver 46 to the planned grinding amount. Was explained. Then, in the grinding step S3, the case where the servo driver 46 updates the target distance each time the scheduled grinding amount updated by the control unit 44 is commanded has been described. However, one aspect of the present invention is not limited to this.

That is, in one aspect of the present invention, the thickness of the workpiece 1 does not have to be repeatedly measured, and the planned grinding amount and the target distance do not have to be updated. More specifically, after the value obtained by subtracting the target thickness of the workpiece 1 from the thickness of the workpiece 1 before grinding is calculated as the planned grinding amount, the chuck table is provided by the target distance corresponding to the planned grinding amount. The grinding of the workpiece 1 may be completed by relatively moving the 8 and the spindles 14a and 14b.

Even in this case, since the control unit 44 can finish grinding the workpiece 1 without instructing the stop of the relative movement of the spindles 14a, 14b, etc., the workpiece 1 is lost even if the control unit 44 stops functioning. There is no problem such as being damaged. Since it is not necessary for the grinding device 2 to measure the thickness of the workpiece 1 to be ground, the thickness measuring units 40 and 42 can be simplified or omitted.

The structure, method, etc. according to the above-described embodiment can be appropriately modified and implemented as long as they do not deviate from the scope of the object of the present invention.

1 Work piece 1a Front surface 1b Back surface 3 Protective member 2 Grinding device 4 Base 6 Turntable 6a Carry-in / carry-out area 6b Rough grinding area 6c Finish grinding area 8 Chuck table 8a Holding surface 8b Porous member 8c Table rotation shaft 8d Table support Table 8e Table rotation motor 10a, 10b Grinding unit 12a, 12b Spindle motor 12c Wheel rotation shaft 14a, 14b Spindle 16a, 16b Wheel mount 18a, 18b Grinding wheel 20a, 20b Grinding wheel 22a, 22b Column 24a, 24b Grinding feed unit 26a, 26b Cassette mount 28a, 28b Cassette 30 Transfer robot 32 Positioning table 34 Loading arm 36 Unloading arm 38 Spinner cleaning device 40, 42 Thickness measuring unit 40a, 40b Probe 40c Post 44 Control unit 46 Servo driver 48 Servo motor 50 Spindle 52 Nut part 54 Lifting plate

Claims (2)

A chuck table having a holding surface for holding the work piece and rotating around an axis intersecting the holding surface.
A spindle that is equipped with a disk-shaped grinding wheel containing a grinding wheel and rotates the grinding wheel in the circumferential direction,
A grinding feed unit having a servomotor that relatively moves the chuck table and the spindle in directions that approach or separate from each other.
A servo driver that sends a signal to the servo motor of the grinding feed unit, and
A grinding method for grinding a workpiece by a grinding device including a control unit for controlling the servo driver.
A holding step of holding the workpiece on the holding surface of the chuck table, and
A value obtained by subtracting the target thickness of the work piece registered in the control unit in advance from the thickness of the work piece is calculated as a planned grinding amount, and the calculated planned grinding amount is ground by the control unit. A grinding amount command step that commands the servo driver of the feed unit, and
While rotating the chuck table and the grinding wheel, respectively, the servo motor of the grinding feed unit relatively moves the chuck table and the spindle in a direction approaching each other, and the subject held by the chuck table. A grinding step for grinding a work piece with the grinding wheel is provided.
In the grinding step, the servo driver ends the relative movement of the chuck table and the spindle when the chuck table and the spindle move relative to each other by a target distance corresponding to the planned grinding amount. A method for processing a workpiece, which is characterized by. The grinding device further includes a thickness measuring unit for measuring the thickness of the workpiece held by the holding surface of the chuck table.
In the grinding amount command step, the thickness of the workpiece is repeatedly measured by the thickness measuring unit until the thickness of the workpiece reaches the target thickness, and the measured thickness of the workpiece is measured. The planned grinding amount is updated by subtracting the target thickness from the above, and the updated scheduled grinding amount is repeatedly commanded by the control unit to the servo driver of the grinding feed unit.
In the grinding step, the servo driver was updated each time the control unit ordered the updated scheduled grinding amount before the chuck table and the spindle moved relative to each other by the target distance. The method for processing a workpiece according to claim 1, wherein the target distance is updated based on the planned grinding amount.