JP2002096259A - Lapping machine equipped with work breakage detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lapping machine equipped with a work breakage detecting apparatus that can surely and immediately detect the breakage of a sheet disc work under lap processing, has simple structure, and is low in cost. SOLUTION: In the lapping machine, both faces of the sheet disc work W of such as a semiconductor wafer are lapped by a pair of lapping surface plates. Limb portions of the work W are rotatably supported by work guiding members 52a, 52b, 52c. The work guiding members 52a, 52c respectively have vibration sensors 53a, 53c, and a work driving roller 73 rotates the work W. A cutout Wn is formed in at least one portion of the limb portions of the rotating work. The vibration sensors respectively detect the frequency that the cutout passes the work guiding members 52a, 52c, and the detection signals are counted by a counter to calculate the actual rotating speed of the work. Rotation signals of the work driving roller 73 is counted to calculate the instruction rotating speed, and the actual rotating speed is compared with the instruction rotating speed. When the difference between the speeds reaches or exceeds a predetermined value, a work breakage detecting unit 56 sends a signal to a control apparatus 57 to carry out emergency stop or the like of the lapping machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin disk-shaped work such as a semiconductor wafer, which is rotatably supported, and a thin disk-shaped work having two smaller lap surfaces than a thin disk-shaped work. More particularly, the present invention relates to a lapping machine for a thin disk-shaped work that laps both sides of a thin disk-shaped work that rotates due to its rotation, and more particularly to a lapping machine provided with a work breakage detection device.

[0002]

2. Description of the Related Art A thin disk-shaped work such as a semiconductor wafer is rotatably supported, and a thin disk-shaped work is sandwiched from both sides by two lap plates having a lap surface smaller in diameter than the thin disk-shaped work. Thus, a lapping machine for a thin disk-shaped work that laps both sides of a rotating thin disk-shaped work has already been proposed. That is, as shown in FIG. 7, a thin disk-shaped work W such as a semiconductor wafer is rotatably supported by four support rollers 101 to 104, and the thin disk-shaped work W is formed by cutting the peripheral edge thereof from both sides. It is designed to be rotationally driven by drive rollers 105 and 106 formed of a conical head. A lap surface plate 107 having a lap surface having a diameter smaller than the diameter of the work W and larger than the radius on both sides of the thin disk-shaped work W.
a and 107b are provided offset with respect to the rotation axis of the work W, the work W is sandwiched between the two lapping plates 107a and 107b, and the whole of both surfaces of the rotating work W is wrapped by the rotation thereof. The lapping machine
For example, it has already been proposed as disclosed in Japanese Patent Application Laid-Open No. 11-267967.

In the lapping machine, a thin disk-shaped work W to be processed is a semiconductor wafer or the like, and is easily broken during the processing. Therefore, a work breakage detecting device is usually provided. That is, generally, as shown in FIGS. 7 and 8, breakage of the work W is detected by providing the photoelectric sensor 108 at a position above the work W where there is no lap surface plate. The photoelectric sensor 108 includes a light emitting unit 108a and a light receiving unit 108b. The light emitted from the light emitting unit a is reflected on the surface of the thin disk-shaped work W, and the returned light is detected by the light receiving unit 108b. Have been.
When the work W is damaged during the processing of the work W, as shown in FIG. 8A, the damaged upper portion falls, and the work W does not exist at the photoelectric sensor 108. Since no signal is output from the sensor 108, the breakage of the work W can be detected.

[0004]

However, even if the thin disk-shaped work W is broken, it does not always fall off as shown in FIG. 8B, and the broken portion exists at the position of the photoelectric sensor 108. In that case, the photoelectric sensor 10
The signal from 8 will be continuously output, and it may not be possible to immediately detect the damage of the work. In addition, since the lapping machine uses a slurry containing a lapping agent, the slurry is scattered during processing and adheres to the light emitting portion and the light receiving portion of the photoelectric sensor 108, which may cause a malfunction.
There were problems such as lack of reliability.

Accordingly, an object of the present invention is to provide a low-cost workpiece damage detecting device which can solve the above-mentioned problems, can reliably and promptly detect breakage of a workpiece during lapping, and has a simple structure and a low cost. Is to provide a lapping machine.

[0006]

In order to solve the above-mentioned problems, a lapping machine provided with a work breakage detecting device according to the present invention comprises:
In a lapping machine for lapping both sides of a thin disk-shaped work with a pair of lapping surfaces, a frequency at which a notch formed in at least one cylindrical portion of a rotating work peripheral portion passes through a predetermined angular position is detected. Notch passage detection means,
Work breakage detecting means for detecting work breakage based on a signal from the notch passage detecting means is provided.

Further, in the lapping machine provided with the work breakage detecting device of the present invention, the work breakage detecting means may further include a command for calculating a command rotation speed of the work based on a rotation speed of a driving roller for driving the work. Rotation speed calculation means, actual rotation speed calculation means for calculating the actual rotation speed of the workpiece based on the signal of the notch passage detection means, and a difference between the command rotation speed and the actual rotation speed is determined. An abnormality determining means for recognizing the breakage of the work when a predetermined value is exceeded and generating an abnormal signal.

In the lapping machine provided with the work breakage detecting device according to the present invention, the notch passage detecting means may further include a work guide member for rotatably supporting a plurality of peripheral portions of the thin disk-shaped work. The work guide member may be any one of a vibration sensor and a pressure sensor that detects a pressure fluctuation on a pressure fluid supply path for hydrodynamically bearing a guide roller in the work guide member.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lapping machine provided with a work breakage detecting device according to the present invention is a lapping machine for lapping both surfaces of a thin disk-shaped work with a pair of lapping plates. A notch passage detecting means for detecting a frequency of the notch formed in one cylinder passing through a predetermined angular position; a work damage detecting means for detecting breakage of the work based on a signal of the notch passage detecting means; Is provided, the breakage of the workpiece during the lapping process can be quickly and reliably detected with a simple structure. Although the work guide member is required at three or more places, the notch passage detecting means may be provided at at least one place, and the structure can be simplified and the breakage of the work can be detected. If the notch passage detection means is provided at several places, the detection of work breakage will be faster and more reliable.
In order to detect the breakage of the work by the signal of the notch passage detection means, it is determined by the signal of the notch passage detection means that the notch does not pass through the predetermined angle position even after the lapse of a predetermined time or more. Or a method of calculating the actual rotational speed of the work based on a signal from the notch passage detecting means and comparing the calculated rotational speed with the commanded rotational speed to detect breakage of the work.

The work damage detection means includes a command rotation speed calculation means for calculating a command rotation speed of the work based on a rotation speed of a drive roller for driving the work, and a signal from the notch passage detection means. Actual rotation speed calculating means for calculating the actual rotation speed of the work by calculating a difference between the command rotation speed and the actual rotation speed, and when the difference between the two speeds becomes equal to or more than a predetermined value, recognizes the damage of the work and generates an abnormal signal. With the configuration including the abnormality determining means that occurs, it is possible to reliably determine the damage of the work. The commanded rotation speed of the work is calculated by counting the signal of the encoder of the drive motor that drives the drive roller with a counter, and the actual rotation speed is calculated by counting the signal of the notch passage detection means with the counter. can do. Based on the difference between the commanded rotation speed of the work calculated based on the rotation speed of the drive roller and the actual rotation speed of the work calculated based on the signal of the notch passage detection means, recognize the breakage of the work and generate an abnormal signal. To generate the difference, the signal of the notch passage sensor is accumulated in an addition / subtraction counter, and the accumulated signal is subtracted by the encoder signal of the drive motor that drives the drive roller to calculate the difference. Thus, the computer can calculate the commanded rotational speed of the work and the actual rotational speed of the work, and can also calculate the difference therebetween.

The notch passage detecting means may be a vibration sensor for detecting vibration of a work guide member rotatably supporting a plurality of peripheral portions of the thin disk-shaped work, or a guide roller for the work guide member. By using any one of the pressure sensors for detecting pressure fluctuations on the pressure fluid supply path, it is possible to detect the passage of the notch as vibration when the notch of the work passes over the guide roller. Since the vibration sensor and the pressure sensor can be attached to the casing of the work guide member, the structure is simple.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view of a lapping machine provided with a work damage detection device according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG. As shown in FIG. 1, a lapping machine provided with a work breakage detecting device of the present invention is disposed on a base 1 so as to face left and right, and has a reference unit having a lap surface plate which is driven to rotate at the center thereof. A work guide unit 5 that rotatably guides and supports a thin disk-shaped work W provided therebetween;
A work rotation drive unit 7 for applying a rotational force to a thin disk-shaped work W rotatably supported by the work guide unit 5.

The reference unit 2 rotatably supports a reference lap surface plate 21 fixed on the base 1 and driven to rotate by a main shaft drive motor 22 with an encoder 23 provided at the left end. The reference lap surface plate 21 is driven to rotate, and is connected to a follow-up lap surface plate 31 which is disposed to face via a constant pressure pressurizing cylinder 24, 24 'and a piston rod 25, 25' provided at the left end. On the other hand, a constant pressure is always applied. On the other hand, the follower unit 3 supported so that the follower lap surface plate 31 can be driven to rotate is mounted on the base 1 so as to be movable left and right so as to face the reference unit 2. Base 1
Servo motor 4 with encoder 45 provided at the right end of
Nut 42 screwed on feed screw 43 rotated by 4
Are fixed to a follow-up unit table 41 on which the follow-up unit 3 is mounted, and the follow-up unit 3 is configured to be able to move left and right by the servomotor 44 with the encoder 45. A follow-up lap surface plate 31 is rotatably supported by the follow-up unit 3, and is driven to rotate by a spindle drive motor 32 with an encoder 33.

The work guide unit 5 comprises a portal gantry 51 fixed to the right end of the reference unit 2 and three work guide members 52a, 52b and 52c supported by the gantry 51. The work rotation drive unit 7 includes a truncated cone 2 sandwiched from both sides of a peripheral portion of a thin disk-shaped work W such as a semiconductor wafer.
The work W is configured to be driven by rotating a drive motor 74 provided on one of the drive rollers 72 and 73.

The reference unit 2 is fixed on the base 1 and rotatably supports a reference lap plate 21 at the center thereof. The reference lap plate 21 is a spindle drive motor with an encoder 23 provided at the left end. The motor 22 is driven to rotate. Further, fixed pressure cylinders 24 and 24 ′ are fixed to the left end of the reference unit 2, and the reference lap surface plate 21 supported in the reference unit 2 is attached to the piston rod 2.
The lapping platen 31 disposed opposite to the lapping platen 31 is always pressurized at a constant pressure via the 5, 25 '. The reference lap surface plate 21 and the following lap surface plate 31
As shown in FIG. 2, an annular wrap surface is formed, and the diameter thereof is set smaller than the diameter of the thin disk-shaped work W such as a semiconductor wafer and slightly larger than the radius. The axis of rotation is arranged to be offset downward with respect to the axis of rotation of the work W such that the lap plate covers the entire lower part of the thin disk-shaped work W. Then, the two lap plates 2 are passed through a plurality of slurry supply holes 35 formed in the main shaft portion 31 of the both lap plates supported by the reference unit 2 and the following unit 3 in the axial direction.
It is configured such that the slurry L in which the lapping agent is mixed is supplied to the surfaces of the first and the 31st.

The follow-up unit 3 is fixed on a follow-up unit table 41 movably mounted on the base 1 so as to be opposed to the reference unit 2. A board 31 is rotatably supported, and the following lap surface plate 31 is rotatably driven by a spindle drive motor 32 with an encoder 33 attached to the right end of the following unit 2. The structure of the following lap surface plate 31 is the same as the structure of the reference lap surface plate 21. In the lower part of the following unit table 41,
A nut 42 is fixed, and the nut 42 is
Servo motor 4 with encoder 45 provided at the right end of
4 and is screwed with a feed screw 43 rotated by the screw 4. Therefore, by controlling and rotating the servo motor 44 with the encoder 45, the follow-up unit table 41 itself is moved left and right via the feed screw 43, the follow-up lap surface plate 31 is moved, and the work W is taken out and attached, and the work is taken out. The distance between the reference lap surface plate 21 and the following lap surface plate 31 can be adjusted based on the thickness of W.

The work guide unit 5 includes a portal gantry 51 fixed to the right end of the reference unit 2 and three work guide members 52a. 52b and 52c. As shown in FIG. 2, work guide members 52 a, 52 b, and 52 c are fixed to the right and left lower and upper ends of the portal gantry 51 so as to project toward the follower unit 3. Note that FIG.
In the embodiment, the three work guide members 52a-552
Although 2c is shown, the number can be appropriately increased if the number is 3 or more. Each work guide member 52a, 52
The guide rollers b and 52c are provided with guide rollers for rotatably supporting the work W, and further include a lower left work guide member 52a and an upper work guide member 52c.
Vibration sensors 53a and 53c are respectively attached to the casings. In addition, each work guide member 52a-
52c may be provided with a guide roller for rotatably supporting the work W as described above, but as shown in FIG. 6 described later, the guide roller bears with a pressurized fluid, and It is preferable to provide a work guide mechanism for supporting both surfaces of the peripheral portion of the thin disk-shaped work W with the ejected fluid. The work guide member 52c provided at the upper end is provided so as to be vertically movable in the direction of the arrow by an air cylinder 54 and to be rotatable in the direction of the arrow by a rotation support member 55 for mounting and removing the work W. Have been.

The work rotation drive unit 7 is attached to a unit support plate 71 which is fixed to the follower unit 3 side of the portal gantry 51 so as to protrude therefrom. The work rotation drive unit 7 is provided on both sides of a peripheral portion of a thin disk-shaped work W such as a semiconductor wafer. Driving rollers 72, 73 comprising two frusto-conical bodies to be pinched
It consists of. One drive roller 73 is provided with a drive motor 74 with an encoder 74E for rotating the roller. One of the drive rollers 73 is swingably supported by the unit support plate 71 around a hinge pin 75, and the swing is performed by an air cylinder 76 attached to the unit support plate 71. It is configured. The two drive rollers 72 and 73 are urged in a direction away from each other by a spring (not shown), and the air cylinder 76 presses the drive roller 73 against the other drive roller 72 against the spring force. The work W is sandwiched by a constant pressure, and a rotation force is applied to the work W by the rotation of the drive motor 74. When the processing is completed, the pressure of the air cylinder 76 is released, so that both drive rollers 7 are
The workpieces 2 and 73 can be separated to remove the processed work W.

The signals from the vibration sensors 53a and 53c attached to the two work guide members 52a and 52c are guided to a work breakage detection unit 56, and are output from the vibration sensors 53a and 52c.
The breakage of the work W is detected from the actual rotation speed of the work W calculated based on the signal from 53c and the command rotation speed of the work calculated based on the rotation speed of the roller drive motor 74 that rotates the work W. , The signal of which is
7 to perform an emergency stop of the machine. A semiconductor wafer, which is a thin disk-shaped workpiece W, is generally provided with a notch Wn on the outer peripheral surface thereof for indicating the crystal orientation of the wafer. The work damage detection device of the present invention detects breakage of the work W by using the notch Wn. For other works, a groove or the like serving as a mark instead of the notch is used, or For a work without a notch, a notch may be carved positively on the outer peripheral portion. In FIG. 2, when the work W rotates and the notch Wn of the work passes through the work guide members 52a and 52c, the vibration sensors 53a and 53c provided on the work guide members 52a and 52c are captured as vibration, and FIG.
A pulse-like output voltage is generated as shown in FIG. The signal is led to the work breakage detection unit 56, and a pulse signal is generated by a pulse circuit through an amplifier (see FIG. 3B).
The pulse is counted by a counter to obtain the actual rotation speed. On the other hand, the encoder 7 of the drive motor 74 that rotationally drives the work W in order to obtain the command rotational speed.
The signal of 4E is also counted by the counter.

Then, these are sent to the computer via the interface, the actual rotation speed and the command rotation speed are calculated from the counter signal, and the difference between the actual rotation speed and the command rotation speed is obtained. When an error occurs, an abnormal signal is generated by recognizing the breakage of the work, and the signal is transmitted to the control device 57 to perform an emergency stop of the machine. In addition to the above-described method, a method of determining whether a workpiece is damaged by a signal from a vibration sensor due to a notch in the workpiece is performed by using the counter in FIG.
May be accumulated by subtracting the pulse signal of the vibration sensor caused by the passage of the vibration signal, subtracting the accumulated value from the signal of the encoder 74E of the drive motor 74, and calculating the difference. In this case, the signal taken from the encoder 74E is a signal output every time the work W makes one rotation. In addition, the breakage of the workpiece may be detected by the cutout signal, in which the cutout Wn does not pass through the predetermined vibration sensor even after the predetermined time has elapsed.

In the embodiment shown in FIG. 2, only two of the three work guide members 52a, 52b and 52c have vibration sensors 53a and 53c.
c is provided, and is configured to output a work breakage signal when an actual rotation speed calculated by a signal of one of the vibration sensors is equal to or greater than a predetermined rotation speed compared to a command rotation speed of the work. The location where the vibration sensor is provided may be provided on all the work guide members, and may be any number as long as it is at least one location. If only one place is provided,
When the work is broken, it is advisable to provide the broken work on the uppermost work guide member 52c which is easy to drop out and easy to detect.

Next, the operation of the lapping machine provided with the work damage detecting device of the present embodiment will be described. First, reference unit 2
Of the constant-pressure pressurizing cylinders 24 and 24 ', the follow-up unit 3 is set to the retreat position, and the upper work guide member 52c
Is raised and rotated to the standby position, and the air cylinder 76 is deactivated, so that the drive rollers 72 and 73 are separated from each other. Therefore, the semiconductor wafer W, which is a thin disk-shaped work, is inserted from the upper part of the gantry 51, and the left and right lower work guide members 52a. It is set on the guide roller 52b. Further, the upper work guide member 52c is rotated,
The work W is lowered and the outer periphery of the work W is supported by the three guide rollers. Next, the servomotor 44 is operated, and the feed screw 4
3, the follow-up unit 3 is advanced, and the reference lap surface plate 2
1. The positional relationship between the work W and the following lap surface plate 31 is set. By operating the air cylinder 76, the two drive rollers 7
The work W is rotated in the direction indicated by the arrow in FIG. 2 (counterclockwise) by driving the drive motor 74 while holding both surfaces of the work W at a constant pressure at 2 and 73. Subsequently, the constant pressure pressurizing cylinders 24 and 24 ′ of the reference unit 2 are operated to apply a predetermined processing pressure between the reference lap surface plate 21 and the following lap surface plate 31, and to supply slurry supply holes to both lap surface plates. The main spindle drive motors 22 and 32 are driven while supplying the slurry L containing the fine abrasive powder through
By rotating the workpieces 1 and 31 in the same direction as the workpiece W, lapping of the workpiece W is performed.

When the work W is rotationally driven, the drive motor 7
The signal of the encoder 74E of No. 4 is counted by a counter, and the computer calculates the commanded rotational speed of the work. On the other hand, each time the work W rotates and the notch Wn passes through the work guide members 52a, 52c, the vibration sensors 53a, 5c provided on the work guide members 52a, 52c.
A signal is issued from 3c, the signal is counted by a counter, and the computer calculates the actual rotational speed of the work. Semiconductor wafer W which is a work during lapping
Is damaged, the rotation of the work W by the drive roller 73 becomes impossible, and any of the work guide members 52a, 52
Since the notch signal is not issued from the vibration sensors 53a and 53c of the workpiece 2c, the actual rotation speed of the workpiece calculated based on the notch signal changes. Control device 5
7, a signal indicating the breakage of the work is sent to the emergency stop of the lapping machine.

FIG. 4 shows a second embodiment using four work guide members and corresponds to FIG. 2 of the first embodiment. Therefore, the other configuration is exactly the same as that of the first embodiment, and the description is omitted. In the second embodiment shown in FIG. 4, the work guide members attached to the gantry 51 are provided at two locations 52c and 52d in the upper and lower parts, in addition to two places 52a and 52b at the lower left and right. I have. Further, vibration sensors for detecting work damage are also provided at the four locations 53a to 53d, so that work damage detection can be performed more reliably and quickly. The upper and lower two work guide members 52c and 52d are attached to the gantry 51 at an angle in relation to the arrangement,
The workpiece W can be moved forward and backward in the radial direction by 4c and 54d, and the workpiece W can be removed upward by being rotated in the direction of the arrow in FIG. 4 by the rotation supporting members 55c and 55d. Is configured.

Each of the work guide members 52a to 52d has
As in the first embodiment, guide rollers for rotatably supporting the work W and vibration sensors 53a, 53b, 53 attached to the casings of the work guide members 52a to 52d.
c and 53d. Each vibration sensor 53a,
The signals 53b, 53c and 53d are sent to the work breakage detection unit 56, respectively, and the actual rotation speed of the work in each work guide member and the encoder of the drive motor 74 for driving the drive roller 73, as in the first embodiment. 74
The difference between the actual rotation speed calculated based on the signal from any one of the vibration sensors of the work guide members 52a to 52d is compared with the command rotation speed of the work calculated based on the signal from E. If this is the case, it will be determined that the workpiece is damaged. Further, each of the vibration sensors 53a, 53b, 53
The time when the notch Wn of the work W passes through each of the work guide members 52a to 52d is measured based on the signals c and 53d, and at that position, it is determined that the next notch signal is not output within a predetermined time. The detection unit 56 may determine that the work is damaged.

FIG. 5 shows a vibration sensor 4 for detecting a work breakage.
This is a display of the state of work breakage when provided on the work guide members 52a to 52d at the locations. In the case of FIG. 5A, a part of the work W (2) is broken and dropped off, and FIG. 5B shows that the work is broken and divided into three pieces, and small pieces W (3) are broken. ) Is a dropout.
FIG. 5C shows a case where the work is similarly divided into three parts, and the small pieces W (3) at the lower part fall off. Since a portion where the roller 73 does not act on the work is generated and the actual rotation of the work is abnormal, any of the vibration sensors 53
Since the actual rotation speed of the work based on the signals from a to 53d is different from the command rotation speed, a breakage of the work can be detected. In the case of FIG. 5 (d), unlike the case described above, the fragments W (1) and W (2) do not fall off immediately due to a relatively complicated break line, and hang around as they are in contact with each other. Is shown. In this case, although the signal due to the notch Wn from the vibration sensors 53a to 53d is usually the same as the signal in most cases, when the broken line portion passes through the work guide member, the vibration caused by the crack is caught and cut. Since a pulse-like signal similar to that of the notched portion is generated, the actual rotation speed of the work based on those signals is abnormal, so that the breakage of the work can be detected. FIG. 5 shows a case where the vibration sensors are provided at four locations. However, if one or more vibration sensors are provided, damage to the work can be detected.

FIG. 6 shows another embodiment of the notch passage detecting means for detecting the notch Wn of the work, and is a sectional view taken along the line BB of FIG. 2 together with the structure of the work guide member. It is shown as. Work guide member 5
2a 'is a casing main body 60 and a casing lid 60'.
And annular guide rolls 5 in the casing.
6 is rotatably supported by the pressure fluid P, and a slit 63 through which the work W can be inserted is formed on the work side of the casings 60 and 60 ′, and an outer peripheral end of the work W inserted into the slit 63. Are directly supported by the guide roll 56.

In the casings 60 and 60 ', a pressure fluid supply path for supplying a jet fluid P for bearing the guide roll 56 and for guiding both surfaces of the work W is formed. A central supply path 61 for supplying the pressurized fluid P to the inner peripheral surface of the annular guide roll 56 is formed at the center of the casing 60, and an extended portion 61 'extends through the casing lid 60'. Pressure sensor 53 at the end
a 'is fixed. Outer supply paths 62, 62 opened on both sides of the work insertion slit 63 are formed on the outer peripheral side of the casings 60, 60 '. The pressure fluid P supplied to the work guide member 52a 'bears on the inner peripheral surface of the guide roll 56, and ejects the pressure fluid P from both sides of the work W inserted into the slit 63 to move the work W to a predetermined position. I'm guiding. At this time, it also plays the role of preventing the slurry L flowing from the center of the work W in the outer circumferential direction due to the centrifugal force from entering the work guide member. A pressure sensor 53a 'for detecting the pressure P of the pressurized fluid is attached to an end of the casing lid 60', and a vibration when the notch Wn of the work W passes through the guide roll 56 is used for the pressure fluid supply pipe 61. , 61 'can be detected as a change in back pressure. Since the notch Wn passing signal by the pressure sensor 53a 'is transmitted as a pulse signal similar to that of the vibration sensor of the first embodiment,
Subsequent processing is the same as in the first embodiment.

[0029]

According to the present invention, a lapping machine provided with a work breakage detecting device according to the present invention is a lapping machine for lapping both surfaces of a thin disk-shaped work with a pair of lapping plates, and at least one cylinder at the periphery of the rotating work. A notch passage detecting means for detecting a frequency of a notch formed at a predetermined position passing through a predetermined angular position; and a work breakage detecting means for detecting breakage of a work based on a signal from the notch passage detecting means. Thus, with a simple structure, damage to the workpiece during lapping can be detected promptly and without malfunction, and the influence on the lapping machine can be minimized. Further, the work damage detection means includes a command rotation speed calculation means for calculating a command rotation speed of the work based on a rotation speed of a driving roller for driving the work, and a work rotation of the work based on a signal from the notch passage detection means. An actual rotation speed calculating means for calculating an actual rotation speed, and a difference between the command rotation speed and the actual rotation speed, and an abnormality which recognizes breakage of the work and generates an abnormality signal when the difference between the two speeds is equal to or more than a predetermined value. By comprising the determination means, it is possible to reliably determine the breakage of the work.

Further, the notch passage detecting means may be a vibration sensor for detecting vibration of a work guide member rotatably supporting a plurality of peripheral portions of the thin disk-shaped work, or a guide roller for the work guide member. Using a pressure sensor that detects pressure fluctuations on the pressure fluid supply path to detect the passage of a work notch with a simple structure that simply attaches the vibration sensor and pressure sensor to the casing of the work guide member. can do.

[Brief description of the drawings]

FIG. 1 is a plan view of a lapping machine provided with a work damage detection device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is an explanatory diagram of a signal of a vibration sensor.

FIG. 4 is a cross-sectional view taken along the line AA of FIG. 1 showing a lapping machine provided with a work damage detection device according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a state of work damage detection in a lapping machine provided with a work damage detection device according to a second embodiment of the present invention.

FIG. 6 is a sectional view taken along the line BB of FIG. 2 showing another embodiment.

FIG. 7 is an explanatory view of a lapping machine provided with a conventional work breakage detection device.

FIG. 8 is an explanatory diagram showing a state of work damage detection in a lapping machine provided with a conventional work damage detection device.

[Explanation of symbols]

 21: Reference lap surface plate 31: Following lap surface plate 5: Work guide unit 52a to 52c: Work guide unit 53a to 53c: Vibration sensor 53a ': Pressure sensor 56: Work breakage detection unit 57: Control device 7: Work rotation drive Unit 73: Work drive roller 74: Work drive motor W: Work (semiconductor wafer) Wn: Notch of work

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Sadaaki Hagino 555 Nakanoya, Annaka-shi, Gunma F-term in the Super Silicon Research Laboratories Co., Ltd. 3C029 CC01 3C034 AA08 AA13 BB71 BB94 CA24 CB13 3C058 AB01 AB04 AB06 AC02 AC03 BA01 BA05 CB06 DA18

Claims (3)

[Claims] In a lapping machine for lapping both surfaces of a thin disk-shaped work with a pair of lapping plates, a notch formed in at least one cylindrical portion of a rotating work peripheral portion passes through a predetermined angular position. A lap provided with a work breakage detecting device, comprising: a notch passage detecting means for detecting a frequency of occurrence of the work; and a work breakage detecting means for detecting work breakage based on a signal from the notch passage detecting means. Board. 2. The method according to claim 1, wherein said workpiece damage detecting means includes a command rotation speed calculating means for calculating a command rotation speed of the work based on a rotation speed of a driving roller for rotating the work, and a signal from said notch passage detecting means. Actual rotation speed calculating means for calculating the actual rotation speed of the work by calculating a difference between the command rotation speed and the actual rotation speed, and when the difference between the two speeds becomes equal to or more than a predetermined value, recognizes the damage of the work and generates an abnormal signal. 2. A lapping machine provided with a workpiece damage detecting device according to claim 1, further comprising means for judging an abnormality that occurs. 3. The notch passage detecting means includes a vibration sensor for detecting vibration of a work guide member rotatably supporting a plurality of peripheral portions of the thin disk-shaped work, or a guide roller in the work guide member. The lapping machine provided with the workpiece damage detecting device according to claim 1 or 2, wherein the lapping machine is constituted by any one of a pressure sensor that detects a pressure fluctuation on a pressure fluid supply path for bearing.