JP7242142B2 - Workpiece processing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of processing a workpiece such as a semiconductor wafer to grind and thin the workpiece.

A device chip mounted on an electronic device is formed, for example, by dividing a disk-shaped semiconductor wafer. A plurality of planned division lines that cross each other are set on the surface of a semiconductor wafer, devices such as ICs are formed in respective regions partitioned by the planned division lines, and the semiconductor wafer is divided along the planned division lines to obtain individual devices. Chips can be made.

2. Description of the Related Art In recent years, there has been a marked trend toward miniaturization of electronic equipment, and demands for smaller and thinner device chips mounted in electronic equipment are increasing. Therefore, in order to manufacture thin device chips, the semiconductor wafer is ground by a grinding machine to be thinned to a predetermined thickness before the semiconductor wafer is divided.

A grinding apparatus includes a chuck table capable of holding a workpiece, and a grinding unit disposed above the chuck table. The grinding unit includes a generally vertical spindle, a spindle motor connected to the upper end of the spindle, and a grinding wheel mounted to the lower end of the spindle. The grinding wheel has grinding wheels arranged in an annular shape on the lower surface facing the upper surface of the chuck table.

The grinding device has a grinding feed unit. The grinding feed unit includes, for example, a servo motor that relatively moves the spindle and the chuck table toward or away from each other, and a servo driver that sends a signal to the servo motor.

When grinding a workpiece with a grinding apparatus, the workpiece is fixed on a chuck table, the chuck table is rotated about an axis perpendicular to the upper surface of the chuck table, and a grinding wheel is used. rotate in the same way. Then, the spindle and the chuck table are relatively moved toward or away from each other. Then, the grinding wheel moving on the circular orbit 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 near the chuck table for measuring the thickness of the workpiece being ground. When grinding a workpiece, the control unit of the grinding device issues a command to the servo driver to start relative movement between the spindle and the chuck table, and the thickness of the workpiece is monitored by the thickness measurement unit while grinding. Cause the unit to perform grinding of the workpiece. Then, when the workpiece reaches a predetermined target thickness, a command is issued to the servo driver to terminate the relative movement.

Japanese Patent Application Laid-Open No. 2003-209080

The control unit of the grinding machine controls the operation of all the units and measuring instruments that make up the grinding machine, and also continuously processes various information. Therefore, for example, the control unit may stop functioning due to an excessive processing load on the control unit after the start of grinding of the workpiece.

A disabled control unit cannot command the servo driver to terminate relative movement between the spindle and chuck table when the workpiece reaches a predetermined target thickness. If the relative movement cannot be completed, not only will the workpiece become thinner than the target thickness, but the workpiece will disappear due to grinding, and the grinding wheel will come into contact with the chuck table, causing serious damage to the grinding machine. be.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and its object is to excessively grind the workpiece even if the control unit of the grinding apparatus stops functioning during the grinding of the workpiece. To provide a method for machining a workpiece without fear and without causing damage to a grinding device.

According to one aspect of the present invention, a chuck table having a holding surface for holding a workpiece and rotating around an axis intersecting the holding surface, and a disk-shaped grinding wheel including a grinding wheel are attached to the grinding wheel. and a servomotor for relatively moving the chuck table and the spindle toward or away from each other; and sending a signal to the servomotor of the grinding feed unit. A grinding apparatus comprising a servo driver, a control unit for controlling the servo driver, and a thickness measuring unit for measuring the thickness of the workpiece held by the holding surface of the chuck table. comprising: a holding step of holding the workpiece on the holding surface of the chuck table; and a thickness measuring unit until the thickness of the workpiece reaches a command reference thickness. The thickness of the work piece is repeatedly measured, and when the measured thickness of the work piece does not reach the command reference thickness, the designated grinding amount registered in advance in the control unit is set to the control unit. a step of repeatedly instructing the servo driver from a grinding amount command step, and while rotating the chuck table and the grinding wheel respectively, the servo motor of the grinding feed unit causes the chuck table and the spindle to move toward each other. and a grinding step of grinding the workpiece held on the chuck table with the grinding wheel, wherein the servo driver adjusts the distance between the chuck table and the spindle. If a new command is not received from the control unit before reaching the target distance, which is closer by a specified distance corresponding to the specified grinding amount, the chuck table is moved when the distance between the chuck table and the spindle reaches the target distance. and the spindle, and in the grinding step, when receiving a new command from the control unit, the servo driver controls the chuck table and the spindle at the time of receiving the new command. The target distance is updated by a value obtained by subtracting the designated distance from the distance from the grinding wheel, and the chuck table and the spindle are relatively moved toward each other by the servomotor to cause the grinding wheel to move the workpiece. A method of processing a workpiece is provided, which comprises grinding the workpiece.

Preferably, the grinding step updates the target distance while the chuck table and the spindle are moving relative to each other.

Also, preferably, in the grinding step, a designated grinding amount update step of updating the designated grinding amount with a smaller value is performed.

Further, preferably, the value of the commanded reference thickness is a value obtained by adding the value of the specified distance to the value of the target thickness of the workpiece.

In the workpiece machining method according to the aspect of the present invention, the control unit does not instruct the servo driver to start and stop the operation. While grinding is performed, the designated grinding amount is repeatedly commanded to the servo driver until the thickness of the workpiece reaches the commanded reference thickness.

In the grinding step, if the specified grinding amount is not commanded until the distance between the chuck table and the spindle reaches the target distance, the servo driver will adjust the relative distance when the distance between the chuck table and the spindle reaches the target distance. stop moving. Then, when the designated grinding amount is commanded, the target distance is updated and the chuck table and the spindle are further moved relative to each other.

In this case, even if the control unit fails while the workpiece is being ground, the calculated target distance remains in the servo driver. Then, when the distance between the chuck table and the spindle reaches the target distance, the servo driver stops the chuck table and the spindle. Therefore, even if the control unit fails while the workpiece is being ground, the workpiece will not be excessively ground and the grinding device will not be damaged.

During grinding of the workpiece, the grinding wheel attached to the grinding wheel is rapidly worn, and the grinding of the workpiece is slow compared to the relative movement distance between the chuck table and the spindle. It may not progress. However, since the thickness of the workpiece is repeatedly measured by the thickness measuring unit and the designated grinding amount is repeatedly instructed to the servo driver, according to the workpiece machining method according to the aspect of the present invention, the workpiece is It can be ground to the target thickness.

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

It is a perspective view which shows a grinding apparatus typically. It is a perspective view which shows a grinding step typically. It is a sectional view showing a grinding step typically. FIG. 4A is a flow chart showing the flow of each step performed in the method for machining a workpiece according to the embodiment, and FIG. 4B is a flow chart showing the flow of the grinding amount instruction step, FIG. 4C is a flow chart showing the flow of the grinding step.

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

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

A plurality of devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integrations) 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 thinned by grinding before the workpiece 1 is divided, thin device chips can be formed by dividing the workpiece 1 afterward. However, the device may not be formed on the surface 1a of the workpiece 1 to be ground.

A method for processing a workpiece according to the present embodiment is performed by a grinding apparatus having a grinding unit. The grinding device 2 will be described below with reference to FIG. FIG. 1 includes a perspective view schematically showing the grinding device 2. As shown in FIG.

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

The protective member 3 includes, for example, a base layer and a glue layer formed on the base layer. When grinding the back surface 1b side of the workpiece 1, the front surface 1a side of the workpiece 1 is supported by a chuck table 8 which will be 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 devices formed on the surface 1a may be damaged when the workpiece 1 is ground. Therefore, a protective member 3 is adhered to the surface 1a side of the workpiece 1. As shown in FIG.

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

A transfer robot 30 is installed on the base 4 at a position adjacent to the cassette mounting tables 26a and 26b. The transport robot 30 unloads the workpiece 1 from the cassette 28a placed on the cassette mounting table 26a, and places the workpiece 1 on the positioning table 32 provided at a position adjacent to the transport robot 30 on the base 4. to convey.

The positioning table 32 has a plurality of positioning pins arranged in a ring. When the workpiece 1 is placed on the central mounting area, the positioning table 32 moves the positioning pins radially inward in conjunction with each other to move the workpiece 1 to a predetermined position. positioned in

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 predetermined position by the positioning table 32 is carried by the loading arm 34 .

A disk-shaped turntable 6 is provided on the central upper surface of the base 4 so as to be rotatable in the horizontal plane. On the upper surface of the turntable 6, for example, three chuck tables 8 are provided which are circumferentially spaced apart from each other by 120 degrees. Each chuck table 8 can be moved by rotating the turntable 6 .

Each chuck table 8 has therein a suction path (not shown) one end of which is 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. As shown in FIG. The holding surface 8a is configured by, for example, the upper surface of the porous member 8b. The chuck table 8 operates the suction source when an object to be held is placed on the holding surface 8a, and applies the generated negative pressure to the object to be held through the porous member 8b, thereby lifting the object to be held. Can hold suction.

The chuck table 8 is fixed on a table support base 8 d provided on the upper surface of the turntable 6 . A table rotating motor 8e fixed on the turntable 6 is connected to the lower surface of the table support base 8d via a spindle. When the table rotating motor 8e is operated, the chuck table 8 fixed to the table support base 8d rotates around the table rotating shaft 8c intersecting 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 loading/unloading area 6 a , the workpiece 1 can be loaded onto the chuck table 8 by the loading arm 34 and unloaded from the chuck table 8 by the unloading arm 36 .

When grinding the workpiece 1, after the workpiece 1 is loaded by the loading arm 34 onto the chuck table 8 positioned in the loading/unloading area 6a, the turntable 6 is rotated to move the chuck table 8. It is moved to the next rough grinding area 6b.

A first grinding unit 10a for rough grinding the back surface 1b side of the workpiece 1 held on the chuck table 8 positioned in the rough grinding area 6b is provided outside the turntable 6 on the upper surface of the rear side of the base 4. are distributed. After rough grinding of the workpiece 1 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.

Outside the turntable 6 on the upper rear side of the base 4, there is a second grinding unit 10b for finish grinding the back surface 1b side of the workpiece 1 held on the chuck table 8 positioned in the finish grinding area 6c. are distributed. The workpiece 1 is finish ground in the second grinding unit 10b. After finish grinding of the workpiece 1 by the second grinding unit 10b, the turntable 6 is rotated to return the chuck table 8 to the loading/unloading area 6a. is carried out from the chuck table 8.

A spinner cleaning device 38 for cleaning and drying the ground workpiece 1 is arranged near the unloading arm 36 on the upper surface of the base 4 and the transfer robot 30 . The workpiece 1 cleaned and dried by the spinner cleaning device 38 is transported from the spinner cleaning device 38 by the transport robot 30 and stored 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. FIG. A column 22a is erected on the rear portion of the base 4. As shown in FIG. A grinding feed unit 24a that supports the first grinding unit 10a movably along the vertical direction is arranged on the front surface of the column 22a. The grinding feed unit 24a includes a spindle 50 extending in the vertical direction, a servo motor 48 connected to the upper end of the spindle 50, and a servo driver 46 connected to the servo motor 48.

Servo driver 46 sends signals to servo motor 48 to control 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 such as a flash memory, and the like. Software that implements the functions of the servo driver 46 is stored in the storage device. Alternatively, the servo driver 46 may be composed of a plurality of modules that integrally implement each function.

A nut portion 52 arranged on the rear surface of an elevating plate 54 is screwed to 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 lifting plate 54 including the nut portion 52 moves up and down. A first grinding unit 10 a is fixed to the front surface of the lifting plate 54 .

The first grinding unit 10a includes a vertically extending spindle 14a 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 attached to 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 actuated, the grinding wheel 18a rotates around the wheel rotation axis 12c perpendicular to the lower surface of the grinding wheel 18a, that is, in the circumferential direction.

When the workpiece 1 is ground in the rough grinding area 6b, first, the grinding wheel 18a is rotated around the wheel rotating shaft 12c to move the grinding wheel 20a along the annular orbit, and the chuck table 8 is moved to the table. Rotate around the rotation axis 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 moved to the It is ground from the back surface 1b side.

The grinding wheel 20a is formed by dispersing abrasive grains made of diamond or the like in a binder, for example. Abrasive grains are moderately exposed from the binder on the contact surface of the grinding wheel 20a that contacts the workpiece 1, and the workpiece 1 is ground by the exposed abrasive grains coming into contact with the workpiece 1. .

A grinding feed unit 24b is arranged on the front face of the column 22b to support the second grinding unit 10b so as to be movable in the vertical direction. The grinding feed unit 24b is configured similarly to the grinding feed unit 24a. The second grinding unit 10b, like the first grinding unit 10a, includes a spindle 14b extending in the vertical direction and a spindle motor 12b connected to the upper end of the spindle 14b.

A disk-shaped wheel mount 16b is provided 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 attached to 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 the wheel rotation axis perpendicular to the bottom surface.

When the workpiece 1 is ground in the finish grinding area 6c, the grinding wheel 18b is rotated to move the grinding wheel 20b along the annular orbit, 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 moved to the It is ground from the back surface 1b side.

In the grinding of the workpiece 1 using the first grinding unit 10a, the workpiece 1 is roughly ground by performing the grinding feed by the grinding feed unit 24a at a relatively high speed. In rough grinding by the first grinding unit 10a, most of the thickness of the workpiece 1 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 workpiece 1 is finish-ground by carrying out the grinding feed by the grinding feed unit 24b at a relatively low speed. In the finish grinding by the second grinding unit 10b, the workpiece 1 is ground to a predetermined 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 functioned as an elevating mechanism for elevating 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 the function of relatively moving the chuck table 8 and the spindles 14a and 14b in the direction 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 near the rough grinding area 6b on the upper surface of the base 4. there is The first thickness measurement unit 40 is, for example, a contact thickness measurement unit. However, the first thickness measuring unit 40 is not limited to a contact-type thickness measuring unit, and may be another type of thickness measuring instrument.

As shown in FIGS. 2 and 3, the first thickness measurement unit 40 includes a first probe 40a that contacts the back surface 1b of the workpiece 1 to measure the height of the back surface 1b, and a chuck table 8. and a second probe 40b that contacts the holding surface 8a to measure the height of the holding surface 8a. Further, a post 40c is provided to support the first probe 40a and the second probe 40b. The first thickness measuring unit 40 can calculate the thickness of the workpiece 1 from the difference between the height of the back surface 1 b of the workpiece 1 and the height of the holding surface 8 a of the chuck table 8 .

A second non-contact thickness measuring unit 42 for measuring the thickness of the workpiece 1 being finish-ground by the second grinding unit 10b is provided near the finish-grinding area 6c on the top surface of the base 4. are arranged. The second thickness measurement 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. It is a laser thickness measurement unit (spectral interference laser displacement meter). However, the second thickness measurement unit 42 is not limited to this.

A contact state between the grinding wheels 20a and 20b and the workpiece 1 during grinding of 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 orbit along 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 the workpiece 1 is ground, the grinding wheels 20a and 20b contact the workpiece 1 in an arc-shaped region extending from the center to the outer circumference of the holding surface 8a of the chuck table 8 and overlapping the annular orbit.

When the workpiece 1 is ground, the grinding wheels 18a and 18b rotate around the wheel rotation axis 12c, and the chuck table 8 rotates around the table rotation axis 8c intersecting the holding surface 8a of the chuck table 8. . As a result, various portions of the back surface 1b of the workpiece 1 are placed one after another on the arcuate region, and the entire back surface 1b of the workpiece 1 is ground.

The grinding machine 2 further comprises a control unit 44 that controls each component of the grinding machine 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 configured by a computer including a processing device such as a CPU and a storage device such as a flash memory. By operating the processing device according to software such as programs stored in the storage device, the control unit functions as concrete means in which the software and the processing device (hardware resources) cooperate.

When the workpiece 1 is ground, 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 relatively move the chuck table 8 and the spindles 14a, 14b of the grinding units 10a, 10b toward each other. to start.

A 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 measure the thickness of the workpiece 1 being ground. 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 measuring device that constitute the grinding apparatus 2, and continuously processes various kinds of information. Therefore, for example, the control unit 44 may stop functioning due to, for example, an excessive processing load being applied to the control unit 44 after the grinding of the workpiece 1 is started.

The disabled control unit 44 cannot command the servo driver 46 to terminate the relative movement between the chuck table 8 and the spindles 14a, 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 will the workpiece 1 become thinner than the target thickness, but the workpiece 1 will disappear due to grinding, and the grinding wheels 20a and 20b will 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 machining a workpiece according to the present embodiment is implemented, when the control unit 44 stops functioning and no command is issued to the servo driver 46, the servo driver 46 will soon start operating the spindles 14a, Grinding feed of 14b etc. is stopped. In this case, even if the control unit 44 cannot issue a command to stop the servo motor 48 to the servo driver 46, the servo driver 46 stops the servo motor 48, so that the workpiece 1 is not excessively ground.

I will explain in detail. The control unit 44 repeatedly measures the thickness of the workpiece 1 with the thickness measuring units 40 and 42 until the thickness of the workpiece 1 reaches the command reference thickness registered in advance in the control unit 44. have a function. If the measured thickness of the workpiece 1 has not reached the command reference thickness, the control unit 44 repeatedly commands the servo driver 46 to specify the grinding amount.

Here, the designated grinding amount is a value set to be smaller than the difference between the thickness of the workpiece 1 before grinding and the target thickness of the workpiece 1 . This value is determined based on the performance of the control unit 44 and the servo driver 46, the speed of the grinding feed performed by the servo motor 48, and the like. As will be described later, the designated grinding amount may be updated so as to gradually decrease according to the progress of grinding.

When the chuck table 8 and the spindles 14a and 14b are relatively moved to the target distance by the specified distance corresponding to the specified grinding amount, the servo driver 46 changes the relative position between the chuck table 8 and the spindles 14a and 14b. stop movement. However, the servo driver 46 is repeatedly instructed by the designated grinding amount from the control unit 44, and the target distance continues to be updated based on the newly instructed designated grinding amount.

In this case, if the control unit 44 fails and no command is sent from the control unit 44 to the servo driver 46, the servo driver 46 controls the servo motor 48 based on the last received command. That is, when the distance between the chuck table 8 and the spindles 14a and 14b reaches the target distance derived from the last specified grinding amount, the servo driver 46 stops the grinding feed.

Here, if the control unit 44 does not stop functioning, the control unit 44 executes the last command to the servo driver 46 when the distance between the chuck table 8 and the spindles 14a and 14b reaches the command reference thickness. Then, when the chuck table 8 and the spindles 14a and 14b are moved relative to each other by a specified distance, the workpiece 1 reaches the target thickness. That is, the value of the commanded reference thickness described above is a value obtained by adding the value of the specified distance to the value of the target thickness of the workpiece.

In summary, the servo driver 46 continues to receive commands from the control unit 44 to gradually advance the grinding of the workpiece 1 while confirming that the control unit 44 is operating normally. Grinding of the workpiece 1 is stopped when the control unit 44 stops functioning and no command is received from the control unit 44 . Therefore, the workpiece 1 is not excessively ground, and the grinding device 2 is not damaged.

A method for processing a workpiece according to this embodiment, which is performed by the grinding apparatus 2, will be described below. In this processing method, a workpiece 1 is ground by a grinding device 2 to be thinned. FIG. 4A is a flow chart showing the flow of each step performed in the method for machining a workpiece according to this embodiment.

In this machining method, a holding step S1 of holding the workpiece 1 on the holding surface 8a of the chuck table 8, a grinding amount command step S2 of repeatedly instructing the servo driver 46 to specify a grinding amount, A grinding step S3 is performed. Each step will be described in detail below.

In the holding step S1, for example, as shown in FIG. 1, the workpiece 1 is accommodated in the cassette 28a with the protective member 3 adhered to the surface 1a side, and the cassette 28a is carried into the grinding device 2. . Then, for example, the workpiece 1 accommodated in the cassette 28 a is carried out using the carrier robot 30 and carried to the positioning table 32 . After the workpiece 1 is positioned at a predetermined position by the positioning table 32, the workpiece 1 is transferred by the loading arm 34 onto the chuck table 8 positioned in the loading/unloading area 6a.

Here, the front surface 1a side of the workpiece 1 is directed downward so that the back surface 1b side of the workpiece 1 to be ground 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 cause the chuck table 8 to hold the workpiece 1 by suction.

In the method for processing a workpiece according to the present embodiment, next, a grinding amount command step S2 and a grinding step S3 are performed. FIG. 4B is a flow chart schematically showing the flow performed in the grinding amount instruction step S2, and FIG. 4C is a flow chart schematically showing the flow performed in the grinding step S3. 2 is a perspective view schematically showing the grinding amount command step S2 and the grinding step S3, and FIG. 3 is a sectional view schematically showing the grinding amount command step S2 and the grinding step S3.

In the grinding step S3, the workpiece 1 is roughly ground using the first grinding unit 10a in the rough grinding region 6b. Alternatively, in the grinding step S3, the roughly ground workpiece 1 is finish ground in the finish grinding region 6c using the second grinding unit 10b. A case where the workpiece 1 is rough-ground using the first grinding unit 10a in the rough-grinding region 6b will be described below as an example.

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

A target thickness of the workpiece 1 when rough grinding is completed is registered in the control unit 44 . In the grinding amount instruction 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 commanded reference thickness to determine whether the thickness of the workpiece 1 has reached the commanded reference thickness (S22). Here, the command reference thickness value is a value obtained by adding a specified distance corresponding to a specified grinding amount described below to the target thickness of the workpiece 1 .

Normally, the thickness of the workpiece 1 has not yet reached the command reference thickness immediately after the grinding amount command step S2 is started. If the thickness of the workpiece 1 has not reached the command reference thickness, the control unit 44 commands the servo driver 46 of the grinding feed unit 24a to specify a grinding amount registered in advance in the control unit 44 (S23). .

When the control unit 44 instructs the servo driver 46 to specify the amount of grinding, the grinding step S3 is started as will be described later, and the workpiece 1 begins to be ground and 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 command reference thickness (S22).

As a result of the determination, when it is determined that the thickness of the workpiece 1 has not reached the command reference thickness, the control unit 44 commands the servo driver 46 of the grinding feed unit 24a to specify the grinding amount (S23). . Therefore, in the machining method of the workpiece according to the present embodiment, the designated grinding amount is repeatedly instructed to the servo driver 46 in the grinding amount instruction step S2.

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

That is, in the grinding amount command step S2, the thickness of the workpiece 1 is repeatedly measured by the first thickness measuring unit 40 until the thickness of the workpiece 1 reaches the command reference thickness. When the measured thickness of the workpiece 1 does not reach the command reference thickness, the control unit 44 repeats the specified grinding amount registered in the control unit 44 to the servo driver 46 of the grinding feed unit 24a. command.

Next, the grinding step S3 will be explained. The grinding step S3 is started while the grinding amount command step S2 is in progress, and proceeds together with the grinding amount command step S2. In the grinding step S3, when the control unit 44 first instructs the servo driver 46 about the specified grinding amount (S31), the target distance between the chuck table 8 and the spindle 14a is calculated based on the specified grinding amount. (S32).

The calculated target distance is the distance between the chuck table 8 and the spindle 14a at the time when the control unit 44 receives the command, and when they are closer to each other by the specified distance corresponding to the specified grinding amount. Substantially, the target distance is a distance that is confirmed to cause no problem at least for the workpiece 1 and the grinding device 2 even if the chuck table 8 and the spindle 14a are brought closer to each other. This is the movement distance of both at this time. The target distance is calculated by the servo driver 46, for example.

Next, while rotating the chuck table 8 around the table rotation axis 8c, the grinding wheel 18a is rotated around the wheel rotation axis 12c. Then, relative movement of the chuck table 8 and the spindle 14a toward each other is started by the servo motor 48 of the grinding feed unit 24a (S33). For example, servo driver 46 initiates operation of servo motor 48 to lower spindle 14a of 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 . When the grinding wheel 20a moving on the circular orbit 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 ground. begin to thin.

The servo driver 46 drives the servo motor 48 aiming at a state in which the distance between the chuck table 8 and the spindle 14a of the first grinding unit 10a is closer to each other by a designated distance corresponding to the designated grinding amount. Control. Then, it is determined whether or not the chuck table 8 and the spindle 14a have relatively moved to the target distance (S34). Usually, the distance between the chuck table 8 and the spindle 14a does not reach the target distance immediately after the start of the grinding step S3.

If it is determined that the chuck table 8 and the spindle 14a have not moved to the target distance, then it is determined whether or not the target distance needs to be updated. That is, as a result of the progress of the grinding amount command step S2, when a new designated grinding amount is commanded from the control unit 44 to the servo driver 46 (S35), the servo driver 46 sets the target grinding amount based on the new designated grinding amount. The distance is updated (S36).

The target distance updated at this time is a value obtained by subtracting the specified distance corresponding to the specified grinding amount from the distance between the chuck table 8 and the spindle 14a at the time when the new command is received. As a result of the progress of the grinding of the workpiece 1, the distance at which it is confirmed that there is no problem even if the chuck table 8 and the spindle 14a approach each other becomes smaller than the existing target distance. The substantial meaning of updating the target distance (S36) is to update the target distance with a distance that is newly confirmed to cause no problem, and to further advance the grinding.

Further, when a new designated grinding amount has not been commanded from the control unit 44 to the servo driver 46 (S35), the target distance is not updated, and based on the latest target distance registered in the servo driver 46 until then. Grinding step S3 continues.

In the grinding step S3, whether or not the target distance is updated, it is periodically and repeatedly determined whether or not the distance between the chuck table 8 and the spindle 14a has reached the target distance (S34). If the distance between the two does not reach the target distance, and if the servo driver 46 is newly instructed to specify a grinding amount from the control unit 44 (S35), the target grinding amount is further based on the new specified grinding amount. The distance is updated (S36).

That is, each time the servo driver 46 receives a command for a newly calculated specified grinding amount from the control unit 44 until the distance between the chuck table 8 and the spindle 14a reaches the target distance, The target distance is updated based on the grinding amount. Then, when the distance between the chuck table 8 and the spindle 14a has reached the target distance (S34), the servo driver 46 stops the servo motor 48 to set the relative position between the chuck table 8 and the spindle 14a. stop moving (S37).

Now, if the control unit 44 does not fail, the last value of the target distance that has been kept updated corresponds to the target thickness of the workpiece 1 . In the method for processing a workpiece according to the present embodiment, the workpiece 1 held on the chuck table 8 is ground to the target thickness by executing the grinding amount command step S2 and the grinding step S3. .

Furthermore, in the grinding step S3, before the thickness of the workpiece 1 reaches the target thickness, the chuck table 8 and the spindle 14a move relative to each other until the distance reaches the target distance. You may stop (S37). In this case, after that, when the designated grinding amount is commanded from the control unit 44 to the servo driver 46 (S31), the target distance is calculated again based on the commanded designated grinding amount (S32), and the relative movement is restarted. (S33).

That is, in the grinding step S3, the relative movement of the chuck table 8 and the spindle 14a may be started and stopped repeatedly. In this case, in the grinding amount instruction step S2, the thickness of the workpiece 1 is measured after the relative movement of the two is stopped (S21), and the control unit 44 outputs the servo signal based on the measured thickness of the workpiece 1. A designated grinding amount is instructed to the driver 46 (S23).

When the relative movement between the chuck table 8 and the spindle 14a is repeatedly started and stopped in this way, the number of commands for the specified grinding amount from the control unit 44 to the servo driver 46 can be minimized. Therefore, the load on the processing capacity of the control unit 44 is lightened, and the malfunction is less likely to occur. However, since an increase in the stop time of the relative movement leads to a decrease in the machining efficiency of the workpiece, the stop time of the relative movement is preferably shorter than the execution time of the relative movement, for example. More preferably, the stop time of relative movement is substantially zero.

Furthermore, the thickness of the workpiece 1 is measured ( The timing of S21) may be adjusted.

For example, the time required from measuring the thickness of the workpiece 1 (S21) to instructing the designated grinding amount (S23, S35) is calculated. Then, the thickness of the workpiece 1 is measured at the required time before the time when the distance between the chuck table 8 and the spindle 14a reaches the target distance (S21). In this case, immediately before the distance between the chuck table 8 and the spindle 14a reaches the target distance (S34), the designated grinding amount is commanded to the servo driver 46 as necessary (S23, S35) to update the target distance. (S36).

Further, for example, as the grinding of the workpiece 1 progresses, the grinding wheel 20a wears, and the thickness of the workpiece 1 increases relative to the relative movement distance between the chuck table 8 and the spindle 14a. The amount of decrease in stiffness may be less. However, in the method for processing a workpiece according to the present embodiment, the thickness of the workpiece 1 is repeatedly measured, the measured thickness of the workpiece 1 is evaluated, and the target distance is repeatedly updated. Therefore, the workpiece 1 is ground by the grinding wheel 20a until the thickness reaches the target thickness.

According to the method for machining a workpiece according to the present embodiment described above, the workpiece 1 is not excessively ground and the grinding device 2 is not damaged even when the control unit 44 stops functioning. Next, a case where the control unit 44 of the grinding device 2 stops functioning while the method for processing a workpiece according to this embodiment is being performed will be described.

The functional stoppage of the control unit 44 refers to a state in which the function of the control unit 44 is stopped due to some abnormal situation, and information processing and command transmission are disabled. Conventionally, the control unit 44 instructs the servo driver 46 to stop the servo motor 48 when the thickness of the workpiece 1 reaches the target thickness. The control unit 44 cannot command the servo driver 46 to stop.

In the method for machining a 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 be continued.

That is, the control unit 44 that has stopped functioning cannot measure the thickness of the workpiece 1 using the first thickness measurement unit 40 (S21), and the thickness of the workpiece 1 exceeds the command reference thickness. It cannot be determined whether or not it has reached the maximum (S22). Then, the designated grinding amount cannot be instructed to the servo driver 46 (S23).

In this case, in the grinding step S3, the control unit 44 does not issue a new specified grinding amount (S35), and the target distance is not updated (S36). That is, when the control unit 44 has stopped functioning, it is repeatedly determined in the grinding step S3 whether the chuck table 8 and the spindle 14a have relatively moved until the distance between them reaches the target distance ( S34).

Then, when the chuck table 8 and the spindle 14a have moved relative to each other until the distance between them reaches the target distance, the relative movement of the chuck table 8 and the spindle 14a is stopped by the servo driver 46 (S37). Therefore, in the method for processing a workpiece according to the present embodiment, the grinding step S3 ends normally even if the control unit 44 stops functioning.

In this case, since the grinding feed by the servomotor 48 is stopped in the middle, the thickness of the workpiece 1 does not reach the target thickness. However, it can be said that the loss is extremely small compared to the conventional case where the workpiece 1 is excessively ground. No physical damage occurs to the grinding device 2, and the workpiece 1 having the target thickness can be obtained by grinding the workpiece 1 again as necessary after restoring the control unit 44. It is from.

That is, in the grinding step S3, after the relative movement is stopped (S37), if the thickness of the workpiece 1 has not reached the target thickness, the function of the control unit 44 is restored to restore the chuck table 8 and the spindle 14a. You may restart the relative movement with. In this case, it is determined whether the chuck table 8 and the spindle 14a have moved relative to each other until the distance reaches the target distance (S34). Grind again until However, the workpiece 1 may not be regrinded.

As described above, in the method for processing a workpiece according to the present embodiment, the grinding amount instruction step S2 may be ended for the reason that the control unit 44 stops functioning. In addition, in the method for machining a workpiece according to the present embodiment, not only is there 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 method for processing a workpiece according to the present embodiment, even if the control unit 44 stops functioning, there is no possibility that the chuck table 8 will be ground by the grinding wheels 20a and 20b and the grinding device 2 will be damaged. do not have. This means that even if the control unit 44 stops functioning, the time required for restoration of the grinding apparatus 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 processing efficiency when processing a plurality of workpieces 1 one after another by the grinding device 2 increases, and the number of workpieces 1 that can be processed per hour increases. In addition, since the workpiece 1 is not lost due to excessive grinding and there is no need to compensate for the loss, the machining cost can be reduced. That is, the machining efficiency of the workpiece 1 that is machined while the control unit 44 is not stopped is also increased.

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

As described above, in the workpiece machining method 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 fear that the grinding device 2 will be damaged.

It should be noted that the present invention is not limited to the description of the above embodiments, 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.

Moreover, although the case where the grinding apparatus 2 includes two grinding units, 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 implemented by a grinding apparatus having one grinding unit, or may be implemented by a grinding apparatus having three or more grinding units.

Furthermore, in the above embodiment, the case where the control unit 44 of the grinding device 2 stops functioning has been described as an example. . 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 the command is transmitted from the control unit 44 to the servo driver 46 A similar effect can be obtained even when the wiring serving as the route is cut.

Also, in the above embodiment, the case where the designated grinding amount is constant has been described, but the designated grinding amount may change according to the progress of the workpiece 1 . For example, at the beginning of grinding, even if the control unit 44 stops functioning, the amount of grinding that can be considered to allow the grinding of the workpiece 1 to proceed without problems is large. The amount of grinding that can be considered to proceed without problems is small.

Therefore, the control unit 44 may reduce the designated grinding amount according to the progress of the workpiece 1 . In this case, for example, in the grinding step S3, a specified grinding amount update step of updating the existing specified grinding amount with a smaller value is performed. The designated grinding amount update step is performed, for example, when the thickness of the workpiece reaches the command reference thickness. Thereby, the final stage of grinding of the workpiece 1 can be performed precisely. Here, it is not necessary to change the relative movement speed of the chuck table 8 and the spindle 14a before and after the specified grinding amount update step.

The structures, methods, and the like according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention.

REFERENCE SIGNS LIST 1 workpiece 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 axis 8d table support Base 8e Table rotating motor 10a, 10b Grinding unit 12a, 12b Spindle motor 12c Wheel rotating 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 mounting table 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 portion 54 Elevating plate

Claims (4)

a chuck table having a holding surface for holding a workpiece and rotating around an axis intersecting the holding surface;
a spindle on which a disk-shaped grinding wheel containing a grinding wheel is mounted and which rotates the grinding wheel in a circumferential direction;
a grinding feed unit having a servomotor for relatively moving the chuck table and the spindle in directions toward or away from each other;
a servo driver sending a signal to the servo motor of the grinding feed unit;
a control unit that controls the servo driver;
a thickness measuring unit that measures the thickness of the workpiece held by the holding surface of the chuck table, the grinding method comprising:
a holding step of holding the workpiece on the holding surface of the chuck table;
The thickness of the workpiece is repeatedly measured by the thickness measuring unit until the thickness of the workpiece reaches the command reference thickness, and the measured thickness of the workpiece reaches the command reference thickness. a grinding amount command step of repeatedly commanding the servo driver from the control unit to specify a grinding amount registered in advance in the control unit when the
While rotating the chuck table and the grinding wheel, the servomotor of the grinding feed unit relatively moves the chuck table and the spindle in a direction toward each other, so that the workpiece held on the chuck table is moved. a grinding step of grinding the workpiece with the grinding wheel;
In the grinding step, if the servo driver does not receive a new command from the control unit before the distance between the chuck table and the spindle approaches the target distance by the specified distance corresponding to the specified grinding amount, stopping relative movement between the chuck table and the spindle when the distance between the chuck table and the spindle reaches the target distance;
In the grinding step, when receiving a new command from the control unit, the servo driver subtracts the designated distance from the distance between the chuck table and the spindle at the time of receiving the new command. A workpiece, wherein the target distance is updated, and the chuck table and the spindle are moved relatively toward each other by the servomotor to grind the workpiece with the grinding wheel. processing method. 2. The method of processing a workpiece according to claim 1, wherein said grinding step updates said target distance while said chuck table and said spindle are moving relative to each other. 3. The method of machining a workpiece according to claim 1, wherein in said grinding step, a specified grinding amount updating step is performed to update said specified grinding amount with a smaller value. 3. The machining of the workpiece according to claim 1, wherein the value of the commanded reference thickness is a value obtained by adding the value of the specified distance to the value of the target thickness of the workpiece. Method.

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