JPH02212045A - Device for detecting defective blade - Google Patents

Abstract

PURPOSE:To correctly detect a defective blade by comparing the difference in the max. value and min. value of the output from a light receiving means with a set reference value on each specific time, forming a pulse signal when exceeding the set reference value and generating a blade damage signal when the counting value exceeds the specific number. CONSTITUTION:A blade 10 held on the work tool assembly body 2 which works a semiconductor wafer 28 located on a holder assembly body 4, is detected by a light projecting means 30 and light receiving means 32 at its shape (wear and defect) of the peripheral edge part. A blade defect detecting means finds the difference by holding the max. value and min. value of the output fed from the light receiving means 32, comparing it with the set reference value each specific time, generating a pulse signal when the difference exceeds the reference value and outputting a blade breakdown signal when the count value exceeds the specific number. Thus, the defect of the blade can correctly be detected without receiving the effect of a work liquid and so on.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a detection device for detecting defects in a blade for processing a workpiece such as a semiconductor wafer.

[Prior art and its drawbacks]

As is well known to those skilled in the art, in the manufacture of semiconductor devices, it is necessary to cut a semiconductor wafer along grid-like cutting lines (commonly referred to as streets) into a number of rectangular regions. . Each of the above rectangular areas is
It is generally called a chip and has a circuit pattern.

Furthermore, in manufacturing magnetic heads, precision processing such as grooving or slicing is performed on metal materials.

For the precision processing of the cutting acid or metal material into semiconductor wafers, a processing device called a dicing saw or a slicer is usually used. This processing device includes a rotatably mounted blade in the form of a sufficiently thin annular plate, a drive source for rotationally driving the blade, and a holder for holding a workpiece. . The blade is usually formed by bonding superabrasive grains, such as synthetic or natural diamond abrasive grains, by an appropriate method such as electrodeposition, resin bonding, or metal bonding. In such a processing device, the holder and the blade are manually or automatically moved relative to each other, so that the rotating blade acts on the workpiece held by the holder, In this way, the required processing is performed on the workpiece.

In this type of processing equipment, it is necessary that the blade be in a suitable condition in order to cut the workpiece with sufficient precision as required. In other words, if the blade becomes excessively worn or damaged due to long-term use, the processing applied to the workpiece will deteriorate and become unacceptable.

Therefore, in order to solve the above-mentioned problem, processing equipment is equipped with a detection device for detecting blade defects. As an example of this detection device, for example,
An example of such a detection device is disclosed in Japanese Patent No. 123210, which includes a light projecting device that projects light toward the blade, and a light receiving device that generates an output signal corresponding to the amount of light received. What is the light emitting means and the light receiving means?
The light emitting device is arranged so that the light emitted from the light emitting device is interfered with by the blade and then received by the light receiving device.

In the above detection device, when the blade is worn beyond a predetermined amount due to long-term use, or when the blade is damaged for some reason, the output signal generated by the light receiving means becomes thick (changes), thus indicating that the blade is in an inappropriate state. In other words, it is detected that a state requiring replacement has been reached.

However, conventional detection devices have a problem in that they are susceptible to the influence of machining fluid applied to the machining area during machining, and erroneous detection is likely to occur due to refraction, diffused reflection, etc. caused by the machining fluid.

[Purpose of the invention]

The present invention has been made in view of the above facts, and its first purpose is to provide an excellent detection device that can accurately detect blade defects mainly due to breakage without being affected by machining fluid or the like. It is to provide.

A second object of the present invention is to provide an excellent detection device that can accurately detect blade defects mainly due to wear without being affected by machining fluid or the like.

[Summary of the invention]

According to the present invention, in response to the first object, a light projecting means projects light toward the peripheral edge of a blade for processing a workpiece, and a light receiving means receives light from the light projecting means. A detection device for detecting blade defects based on an output signal from the light receiving means, comprising: a maximum value holding means for holding the maximum value (M) of the output signal from the light receiving means; , minimum value holding means for holding the minimum value (m) of the output signal from the light receiving means; and the maximum value (M) held by the maximum value holding means and the minimum value held by the minimum value holding means. Difference (M-m) between the minimum values (m)
and a set standard value (Vo); m ) ＞
V @ ) pulse signal generation means for generating a pulse signal when the pulse signal is generated; failure signal generation means for generating a failure signal in relation to the pulse signal from the pulse signal generation means; and failure counting means for counting the failure signals. and, during the blade defect detection operation, the maximum value (M) and the minimum value held in the maximum value holding means by the comparison means are determined at each first set time interval (T,). The difference (M-m) between the minimum value (m) held in the value holding means and the set reference value (
Vo), the failure signal generating means generates the failure signal when the pulse signal generation means successively generates the pulse signal, and the failure counting means generates the failure signal for a second set time (Vo). A detection device is provided, characterized in that when the number of defective pulse signals exceeds a predetermined number within T2), a blade breakage signal is generated.

In the detection device as described above, during the defect detection operation, the maximum value (M) held in the maximum value holding means and the minimum value (m
) is compared with the set reference value (■・), and since the defective signal generating means generates a defective signal only when the pulse signal generating means continuously generates pulse signals, Even if the light receiving means makes a false detection and the pulse signal generating means generates a pulse signal once, a defective signal will not be generated as long as this pulse signal is not continuously generated. It is possible to extremely reduce false detections caused by machining fluid, etc. In addition, since the defect counting means generates a blade breakage signal when the number of defective signals exceeds a predetermined number within a second set time (T2), in the case of the conventional technology that generates a blade breakage signal at the time when a defective signal is generated. Compared to this, the above-mentioned false detections caused by machining fluid etc. can be further reduced.

Further, according to the present invention, in accordance with the second object, there is provided a light projecting means for projecting light toward the peripheral edge of a blade for processing a workpiece, and a light projecting means for receiving light from the light projecting means. A detection device comprising an optical detection means consisting of a light receiving means and detecting a defect in a blade based on an output signal from the light receiving means, comprising: a low frequency passing means that passes only low frequency signals; and a set reference value, the output signal from the light receiving means is sent to the comparing means through the low frequency passing means, and the comparing means compares the signal value from the low frequency passing means. A detection device is provided, characterized in that it generates a blade wear signal when the blade wear signal exceeds the set reference value.

In the detection device described above, since the output signal from the light receiving means is sent to the comparison means through the low frequency passing means, fluctuations in the output signal caused by machining fluid etc. are cut by the low frequency passing means. This makes it possible to significantly reduce false detections caused by machining fluid and the like when detecting blade wear.

〔Concrete example〕

Further details will be given below with reference to the accompanying drawings.

1 to 3 showing a processing apparatus equipped with an embodiment of the detection device according to the present invention, the illustrated processing apparatus is suitable for cutting, for example, a semiconductor wafer along grid cutting lines, i.e., streets. has a processing tool assembly, generally designated 2, and a holding tool assembly, designated generally 4.

The processing tool assembly 2 includes a support frame (not shown) that is attached to be able to reciprocate in a predetermined direction (left-right direction in FIG. 1, direction perpendicular to the plane of the paper in FIG. 2, and up-down direction in FIG. 3). It is equipped with A shaft 6 (FIGS. 1 and 2) extending substantially horizontally to the left in FIG. 2 is rotatably mounted on this support frame. A drive source 8, which may be an electric motor, is further attached to the support frame.
is drivingly connected to the shaft 6 via suitable transmission means (not shown). A rotary processing tool 12 having a blade 10 is attached to the free end of the shaft 6, that is, the right end in FIG. This rotary processing tool 12 includes a pair of support flanges 14, and a blade 10 in the form of an annular plate is held between the pair of support flanges 14. As clearly illustrated in FIGS. 1-3, the outer diameter of the blade 10 is greater than the outer diameter of the support flange 14, and the outer circumferential edge of the blade 10 projects beyond the outer circumferential edge of the support flange 14. There is. The blade 10 itself is conveniently formed by bonding superabrasive grains, such as synthetic or natural diamond abrasive grains, by an appropriate method such as electrodeposition, resin bonding, or metal bonding. This rotary processing tool 12
The support frame body to which the is attached is vertically adjustable.

This support frame is also provided with a machining fluid supply means 16 for supplying machining fluid such as water to the machining area. A pair of supply pipes 18a and 18b are provided. One end of one supply pipe 18a is disposed on one side of the rotary processing tool 12 (left side in FIG. 2, right side in FIG. 3), and the other supply pipe 18b One end portion of the rotary processing tool 12 is disposed on the other side (the right side in FIG. 2, the left side in FIG. 3), and these extend substantially horizontally along the blade IO. A plurality of holes are formed at intervals in the axial direction in the downward side portions of the supply pipes 18a and 18b. The other ends of these supply pipes 18a and 18b are connected to a machining fluid supply source 20 such as a pump. Therefore, the machining fluid supplied from the machining fluid supply means 20 to the supply pipes 18a and 18b is supplied to the machining area as shown by arrows in FIGS. 2 and 3.

The retainer assembly 4 includes a retainer 2 having a substantially horizontal upper surface.
It is equipped with 4. This holder 24 is rotatably mounted around a central axis that extends substantially vertically, and in a direction perpendicular to the above-mentioned predetermined direction (a direction perpendicular to the plane of paper in FIG. It is mounted so that it can move freely in the left and right directions. At least the central region of the retainer 24 is breathable and selectively communicated with a suction source 26 (FIGS. 1 and 2) by suitable vent means (not shown).

In the processing apparatus described above, a workpiece, in the illustrated case a semiconductor wafer 28, is placed on the upper surface of the holder 24. Then, the holder 24 is communicated with the suction source 26, and the semiconductor wafer 28 is vacuum-adsorbed onto the upper surface of the holder 24. On the other hand, the processing tool assembly 20 support frame is positioned at a height that allows the lower end of the blade 10 of the rotary processing tool 12 to act on the semiconductor wafer 28 as desired. Next, the drive source 8 is energized to rotate the shaft 6 and the rotary processing tool 12 attached thereto at high speed. Then, the support frame of the processing tool assembly 2 is reciprocated in the predetermined direction by an appropriate drive source (not shown), and an appropriate drive source (not shown) is reciprocated for each forward and backward movement of the support frame. (not shown) allows the holder 24 to be indexed and moved in a direction perpendicular to the predetermined direction. Thus, the blade 10 of the rotary processing tool 12 acts on the semiconductor wafer 28 in the processing area, and the semiconductor wafer 28 is cut along a plurality of parallel cutting lines (not shown) extending vertically in FIG. . Thereafter, the holder 24 is rotated 90 degrees about a substantially vertical central axis by an appropriate drive source (not shown), and then the above-mentioned reciprocating movement of the support frame of the tool assembly 2 and the holder 24 are rotated by an appropriate drive source (not shown). 24 of the above-described index movements are performed. Thus, the blade 1 of the rotary processing tool 12
0, the semiconductor wafer 28 is cut along a plurality of other parallel cutting lines that extend substantially perpendicular to the plurality of parallel cutting lines that have already been cut. Thus, the semiconductor wafer 28 is cut into a number of rectangular regions, or chips (such cutting of the semiconductor wafer 28 is done by cutting the semiconductor wafer 28, leaving some uncut thickness in the semiconductor wafer 28, as is well known to those skilled in the art). Alternatively, if a tape is attached to the back side of the semiconductor wafer 28, the tape may be removed and the semiconductor wafer 28 may be cut over its entire thickness). A processing liquid such as water is injected from the cooling liquid supply means 16 toward the processing area, and the cooling liquid is supplied to the blade 10 and the semiconductor wafer 28 which are being cut.

The above-described configuration and operation of the illustrated processing device are already known and also represent only one example of the processing device to which the present invention is applied, and therefore the details of the configuration and operation of the illustrated processing device are explained below. , the description thereof will be omitted in this specification.

The processing device is further equipped with a detection device for detecting defects in the blade 10. 2 and 3), the light projecting means 30 is equipped with a light emitting element 34, and the light receiving means 32 is equipped with a light receiving element 36.

The light-emitting element 34 may be, for example, a light-emitting source capable of emitting infrared light, and the light-receiving element 36 is composed of a phototransistor (preferably an element having light-receiving sensitivity matching the wavelength of light from the light-emitting source). can do. The light projecting means 30 includes a light transmitting means 38 for guiding light from the light emitting element 34 to the monitor area, and the light receiving means 32 includes a light transmitting means 4 for guiding the light from the monitor area to the light receiving element 36.
0, and these optical transmission means 38 and 40 can be constructed from one or more optical fibers.

In a specific example, one end, that is, the input end of the optical transmission means 38 is optically connected to the light emitting element 34, and the other end, that is, the output end is connected to one side of the blade IO (left side in FIG. 2, right side in FIG. 3). Located in close proximity to the monitor area. Further, one end of the other optical transmission means 40, that is, the input end is connected to the other side of the blade 10 (the second right side, The other end, ie, the output end, is optically connected to the light receiving element 36. In the specific example, the other end of the optical transmission means 38 and one end of the optical transmission means 40 are further covered with flexible protective members 42 and 44, so that the relative position with respect to the blade 10 can be finely adjusted. It is attached to the support frame via appropriate support means (not shown) so that the support member can be attached to the support frame. The end surfaces of the protective members 42 and 44, that is, the output end of the optical transmission means 38 and the input end of the other optical transmission means 40, are further coated with sapphire to prevent these end surfaces from being damaged by scattering cutting chips, etc. A piece 46 is provided.

Such a detection device further includes a gas flow generating means for ejecting a gas such as air into or near the monitoring area.
8 and a hollow cylindrical gas supply pipe 50 extending from the gas supply source 48 to the vicinity of the monitor area, and the gas, which may be air, is passed from the gas supply source 48 through the gas supply pipe 50 to the monitor area or its vicinity. is injected into. Therefore, the fog generated by the injection of machining fluid during machining and/or debris from machining are prevented from entering the monitoring area or its vicinity by the gas injected and flowing from the gas flow supply pipe 50. The above-mentioned fog and/or debris are removed from the optical transmission means 38.
Floating in the optical path between the output end of the optical transmission means 3 and the blade 10 and/or the optical path between the blade IO and the input end of the optical transmission means 40 or the output end of the optical transmission means 3 and the input end of the optical transmission means 40 It is reliably prevented from adhering to the surface of the sapphire piece 46 covering the sapphire. In the specific example, one end of the gas flow supply pipe 50 is branched into two parts, one of which 50a is disposed on one side of the blade 10, and the other 50b is disposed on the other side of the blade 10. . In connection with this, the part of the gas flow supply pipe 50 (one output end)
50a is arranged between the blade 10 and the output end of the optical transmission means 38 so as to face the output end somewhat, and the output end of the portion 50a is formed obliquely so that the portion on the blade 10 side protrudes. There is. Further, the other part (the other output end) 50b of the gas flow supply pipe 50 is arranged between the blade 10 and the input end of the optical transmission means 40 so as to face the input end somewhat, and at the part 50b The output end is formed obliquely so that the part on the blade 10 side protrudes.

With this configuration, the portion 50 of the gas flow supply pipe 50
The gas flow injected from a as shown by the arrow (FIG. 3) is directed somewhat toward the output end of the light transmission means 38, and the end of the blade 1 moves from the upper end to the lower end when looking at this output.
0, and the gas flow injected from the portion 50b of the gas flow supply pipe 50 as shown by the arrow (FIG. 3) is directed somewhat towards the input end of the optical transmission means 40 and the input end. This prevents the gas flow injected from the gas flow supply pipe 50 from flowing toward the blade 10, and can effectively suppress vibration of the blade 10. Further, as can be easily understood from FIG. 3, the gas flows injected from the sections 50a and 50b of the gas flow supply pipe 50 flow substantially symmetrically on both sides of the blade 10, In this way, the occurrence of curling of the blade 10 can be further reduced.

In a specific example, as can be seen from FIGS. 1 to 3, the monitor area is the periphery of the blade IO, specifically the area indicated by the arrow 52.
It is arranged at the center in the vertical direction in the rotational direction of the blade 10 as shown by , that is, at the center in the vertical direction on the right side of FIG. By arranging it in this way, the monitor area can be moved away from the machining area, thereby reducing the influence of the machining fluid when detecting defects in the blade 10. Although not shown in the processing apparatus, a cover member is attached to the support frame so as to cover the processing area and the monitor area, and the rotary processing tool 1 is mounted within this cover member.
2. An output end of the optical transmission means 38, an input end of the optical transmission means 40, one end of the supply pipes 18a and 18b, etc. are provided.

In this processing device, a light projecting means 30 is used in the monitor area.
The light projected towards the blade 10 from the blade 1
The light is received by the light receiving means 32 located on the opposite side of 0, and the thus received light is processed as shown in FIG. That is, the light receiving element 36 of the light receiving means 32 generates an output signal proportional to the amount of received light, and this output signal is sent to the terminal 52 in FIG.
will be sent to Based on the output signal thus sent, the blade damage/failure detecting means, generally indicated by number 54, and the blade wear/failure detecting means, generally indicated by number 56, detect damage and wear of the blade 10 during machining. be detected on the street.

The blade breakage defect detection means 54 of the specific example includes a maximum value holding means 58 which can be constructed from a maximum value holding circuit and a minimum value holding means 60 which can be constructed from a minimum value holding circuit. The output signal from the light receiving element 36 is sent to the maximum value holding means 58 and the minimum value holding means 60, and the maximum value holding means 58 holds the largest value (M) of these output signals, and the minimum value holding means 60 holds the smallest value (m) of the above output signals. The signals from the Jll value holding means 58 and the minimum value holding means 60 are sent to an operational amplification means 62 such as a differential operational amplifier circuit, and the operational amplification means 62 receives the maximum value (M) from the maximum value holding means 58.
2 The difference (M-) from the minimum value (m) from the minimum value holding means 60
m) as required. The output signal from the operational amplification means 62 is sent to a comparison means 64, such as a comparator circuit.

The comparison means 64 includes a reference value setting means 6 such as a voltage setting circuit.
6 is connected, and the setting reference (II(V,)) set by the reference value setting means 66 is sent to the comparison means 64. This comparison means 64 receives the output signal from the operational amplification means 62, The difference between the above maximum value (M) and the above minimum value (m) (
M-m) is compared with the signal from the reference value setting means 66, that is, the set reference value (Vo), and the difference (M-m) between the maximum value (M) and the minimum value (m) is determined as the set standard. (!!(V0
) is greater than ((M m) > Vo ). The output signal from the comparison means 64 is fed to a pulse signal generation means 68, such as a square wave generation circuit, which generates a pulse signal based on the output signal from the comparison means 64. The pulse signal from the pulse signal generation means 68 is sent to a frequency-voltage conversion means 70 such as a frequency-voltage conversion circuit, and the frequency-voltage conversion means 70 converts the frequency from the interval of the pulse signal from the pulse signal generation means 68. Calculate and convert such frequency to voltage.

The output signal from the frequency-to-voltage conversion means 70 is fed to a comparison means 72, such as a range comparison circuit.
indicates that the output signal is within a predetermined range, in other words, it is greater than the first set reference value (vl) and the second set reference value (vl).
vl), and if it is within the predetermined range, an output signal is generated. In a specific example, the frequency-voltage conversion means 70 and the comparison means 72 constitute a defective signal generation means, and the signal output from the comparison means 72 becomes a defective signal. This defective signal is detected by a defective signal counting means 74 such as a measuring circuit.
will be sent to Incidentally, instead of directly sending the signal from the comparing means 72 to the defective signal counting means 74, a gate is provided between the pulp signal generating means 68 and the defective signal counting means 74, and the gate is activated based on the signal. It may be opened so that the signal from the pulse signal generating means 68 is fed to the defect counting means 74, which is also fed a signal from the timer means 76. The counting means 74 counts the number of defective pulse signals within a set time (second set time) (Tz) set by the timer means 76,
When the number of defective pulse signals exceeds a predetermined value (No. 2), a blade damage signal is generated. This blade damage signal is sent to a display means 78, such as a warning lamp, and to the drive source 8, and the display means 78 lights up to indicate that the blade 10 must be replaced, and the drive source 8 is deenergized. to stop machining.

Further, the blade wear defect detection means 56 of the specific example includes a low frequency pass means 80 such as a low frequency pass circuit. This low frequency pass means 80 passes only low frequency output signals from the light receiving element 36, and the signal from the low frequency pass means 80 is sent to a comparison means 82 such as a comparison calculation circuit. A reference value setting means 84 such as a voltage setting circuit is connected to the comparison means 82 , and a set reference value (V) set by the reference value setting means 84 is sent to the comparison means 82 . This comparing means 82 compares the output signal from the low frequency passing means 80 and the signal from the reference value setting means 84, that is, the set reference value (V), and the signal value from the low frequency passing means 80 is determined as the set reference value. An output signal, ie a blade wear signal, is generated when the value (V) is greater than the value (V). This blade wear signal is sent to a display means 84, such as a warning lamp, which illuminates to indicate that the blade 10 has worn beyond an acceptable value.

In this embodiment, the indicator 78 lights red to indicate that the blade 10 is damaged, and the indicator 84 lights yellow to indicate that the blade 10 is worn.

Alternatively, a common display means may be illuminated by the blade breakage signal and the blade wear signal.

Further, in the specific example, the drive source 8 is stopped only when the blade damage signal is generated, but instead of this, the drive source 8 may also be stopped when the blade wear signal is generated. good.

Blade damage detection means 54 and blade wear detection means 5
The detection operation according to No. 6 will be explained as follows.

Detection of blade breakage will be described mainly with reference to FIGS. 4 and 5. The output signal from the light receiving element 36 of the light receiving means 32 is detected by the maximum value holding means 58 and the minimum value holding means 6.
0, step n-1 to step n-2
, the maximum value holding means 58 holds the maximum value (
M) is held, and when a signal with a value larger than the above-mentioned holding value is input, the large value is held instead of the above-mentioned holding value.

Further, the minimum value holding means 60 holds the minimum value (m) of the output signals, and when a signal with a value smaller than the held value is manually input, this small value is held in place of the held value.

The maximum value (M) held in the maximum value holding means 58 and the minimum value (m) held in the minimum value holding means 60 are sent to the operational amplification means 62, and in step n-3, this maximum value ( M
) and the minimum value (m) (M-m) is calculated, and the above difference (
Mm) is amplified. The output signal from the operational amplification means 62 is sent to the comparison means 64, and in step n-4 it is determined whether the difference (M-m) is larger than the set reference value (V,). In the device of the specific example, the blade 10 is chipped 6
0 μm corresponds to a set reference value of 0.4 V set by the reference value setting means 66, and the above difference (M−m) is 0.4 V.
When the voltage is 4V or less, it is determined that there is no relatively large damage to the blade IO (no chipping of 60 μm or more), and step n
-4 returns to step n-1, and the above operations are repeated. On the other hand, if the above difference (M-m) exceeds 0.4V, it is determined that there is a possibility of damage to the blade 10 (a chip of 60 μm or more may have occurred), and step n-
4 to step n-5.

Thus, the pulse signal generation means 68 generates a pulse signal based on the output signal from the comparison means 64, and in step n-6, the timer means 76 is activated by the pulse signal.
is set. In a specific example, the timer means 76 times up, for example, when the hand reaches 0.5 seconds, and the following blade defect detection operation is performed until the timer means 76 times up. In a specific example, the pulse signal generating means 68 includes a tie--I:6, which generates a signal every quantification time (T1), and by such a signal. Maximum value holding means 5
8 and the minimum value holding means 60 are reset, and the new maximum value (M) held in the maximum value holding means 58 and the new minimum value (m) held in the minimum value holding means 60 are sent to the comparison means 64. will be sent.

In the specific example device, the blade lO is 30,000r.

In this connection, the first set time (T1) is 60/30000 seconds, that is, 0.
002 seconds (preferably 0.001 seconds taking into account the error)
(preferably on the order of 8 seconds), so that the timer means 86 generates an output signal substantially every revolution of the blade IO.

When the blade defect detection operation is started, step n-7
As described above, the maximum value (M) held in the maximum value holding means 58 and the minimum value (m) held in the minimum value holding means 60 are released (neseL), and then step n-8 At , the maximum value holding means 58 newly sets the maximum value (
M) is held, and the minimum value holding means 60 holds a new minimum value (m). The maximum value (M) and minimum value (m) thus held are processed by the operational amplification means 6 in the same manner as described above.
2, and in step n-9, this maximum value (M)
The difference (M-m) between the minimum value (m) and the minimum value (m) is calculated, and the above difference (M
-m) is amplified. The output signal from the operational amplification means 62 is sent to the comparison means 64, and in step n-10, it is determined whether the difference (M-m) is larger than the set reference value (■.). When the difference (M-m) is less than the set reference value (V.), it is determined that there is substantially no relatively large damage to the blade 10, and step n-1
The process returns to step n-7 again from 0, and the above operation is repeated every first set time (T1).

On the other hand, if the difference (M-m) exceeds the set reference value (■.), it is determined that there is relatively large damage to the blade 10, and the process moves from step n-10 to step n-11. In step n-11, the frequency-voltage conversion means 7 receives the signal sent from the pulse signal generation means 68.
0 calculates the frequency based on the interval between two consecutive pulse signals, and converts the calculated value into a voltage.

The output signal from this frequency-to-voltage conversion means 70 is fed to a comparison means 72, followed by step n-12.
It is determined whether the frequency is within a predetermined range.

In a specific example, the comparison means 72 determines that the frequency of the pulse signal is 48
A fault signal is generated when the frequency is within the range of 0 to 520 Hz. That is, when the pulse signal generating means 68 continuously generates a pulse signal, in other words, every 0.002 seconds, the frequency becomes substantially 500 Hz, and at this time, the voltage from the frequency-voltage converting means 70 ranges from 480 to 520 Hz.
is within the predetermined range corresponding to step n-1.
2, the process proceeds to step n-13, where the comparison means 72 generates a defective signal. On the other hand, when the pulse signal generating means 68 does not continuously generate pulse signals (generates the next pulse signal after 0.004 seconds or more), the frequency is lower than 480 Hz (for example, when the pulse signal is 1 When it is generated every third time, the frequency is 250Hz,
Furthermore, when the above pulse signals are generated every second, the frequency becomes 167Hz, and in both cases, the frequency becomes 48Hz.
becomes smaller than 0&. ) At this time, the voltage from the frequency-voltage conversion means 70 is smaller than the value corresponding to 4807, so the comparison means 72 does not generate a defective pulse signal, and steps n-12 to n-7
Return to As described above, when there is a relatively large chip in the blade 10, the pulse signal generating means 68 will continuously generate pulse signals, as will be easily understood, so that the comparing means 72 will Generate a bad pulse signal. On the other hand, when there is no relatively large chip on the blade 10 and the pulse signal generation means 68 erroneously generates a pulse signal due to the influence of machining fluid, etc.
The pulse signal generating means 68 rarely generates pulse signals continuously, and almost no defective pulse signals are generated. Therefore, false detection caused by machining fluid or the like is reliably prevented.

When a defective signal is generated in step n-13, the defective pulse signal is sent to the counting means 74, and in step n-13, the defective pulse signal is sent to counting means 74.
At step n-14, the counting means 74 counts the number of defective signals generated since the blade defect detection operation was started.Next, at step n-15, the counting means 74 counts whether the number of defective pulse signals exceeds the predetermined number or not. will be judged. In the specific example, 0
．． If the pulse signal generation means 68 generates a pulse signal every 0.002 seconds, the comparison means 72 generates a pulse signal every 0.002 seconds. A maximum of 249 defective pulse signals will be generated in 5 seconds, and in connection with this, the predetermined number is set to 125, for example. This number is determined based on experiments, and in a specific example, if 125 pieces were generated during the second predetermined time (T2), there was a substantially 100% probability that the blade 10 would be damaged. If the count value in the counting means 74 is less than the predetermined value (for example, 125), the process proceeds from step n-15 to step n-16, and the timer means 76 has timed up, or in other words, it has not been determined whether the timer means 76 has timed up or has elapsed since the blade defect detection operation was started. 2 predetermined time (T2), for example 0. It is determined whether 5 seconds have passed. If the timer means 76 has not timed up, the process returns from step n-16 to step n-7, and the above-described operations are repeated until the timer means 76 times out. on the other hand,
When the second predetermined time (T2) has elapsed without generating a predetermined number of defective signals, the process proceeds from step n-16 to step n-17, and the count value of the counting means 74 is reset. Furthermore, the process proceeds to step n-18 and the timer means 7
6 and 86 are reset, and then the process returns to step n-1. Therefore, even if the pulse signal generating means 68 generates a pulse signal due to an erroneous detection and the blade defect detection operation is started, if there is substantially no chipping in the blade 10, the second predetermined time period (T2) will continue. The predetermined number of defective signals are not generated during the period of time, so the blade failure signal described later is not generated, and there is no false detection of blade failure. Although the maximum value holding means 58 and the minimum value holding means 60 are not reset at the time when is reset, they may be reset.

In response to this, the timer means 76 times up.
In other words, after the blade defect detection operation starts, the second
If the counting means 74 counts a predetermined number (for example, 125) of defective signals before the predetermined time (T2) of source 8.

The process then proceeds from step n-15 to step n-19, where the display means 78 is energized, and thus the display means 78
indicates that a relatively large chip has occurred in the blade 10. Further, in step n-20, the drive source 8 is deenergized, and processing on the semiconductor wafer 28 is temporarily stopped. Note that the above-mentioned abnormal stop state is caused by the damaged blade 10.
After replacing the blade with a new blade IO, press the reset switch (
(not shown).

In the specific example, the blade damage signal is generated when the counting means 74 counts a predetermined number of defective signals before the timer means 76 times up. 74
The blade breakage signal may be generated when the count value of is greater than the predetermined constant;
For example, the count value of the defective signal counting means 74 is judged at intervals of 0.5 seconds, and when the count value is larger than a predetermined number (for example, 125), the display means 78 is energized, and when it is smaller than the predetermined number, the counting means 74 is activated. Alternatively, the number of defective pulse signals at a predetermined time interval may be determined.

Next, referring mainly to FIGS. 4 and 6, the detection of blade wear will be described. In addition to the maximum value holding means 58 and the minimum value holding means 60, the output signal from the light receiving element 36 of the light receiving means 32 is Blade wear defect detection means 56
It is also sent to low frequency passing means 80 at. This low frequency passing means 80 may be one that passes low frequencies of, for example, 57 or less, and when the output signal passes through the low frequency passing means 80, relatively high frequency parts (parts exceeding 5 Hz) are cut off. be done. As can be understood from the above description, the relatively high frequency portion of the output signal is
This occurs due to chipping of the blade 10 and unevenness on its surface, and also due to the adverse effects of machining fluid and the like. Therefore,
By cutting the above-mentioned relatively high frequency portion, only the change in the output signal related to the wear of the blade 10 remains, and thus, by passing the output signal from the light receiving element 36 through the low frequency passing means 80, the wear of the blade 10 is reduced. Can be detected accurately.

The output signal passes through the low frequency passing means 80 to the comparing means 8.
2, step n-101 to step n
-102, it is determined whether the output signal value is greater than a set reference value (V). In the specific example device, for example, the allowable blade wear of 800 μm is set as the reference value setting means 84.
When the output signal value is less than or equal to the set reference value (V), that is, 4 V, the blade 10 is not relatively worn (8 V).
00βm or more)), and step n-
From step n-102, the process returns to step n-101, and the above operations are repeated. On the other hand, the above output signal value is the set reference value (V
), that is, exceeds 4v, it is determined that the blade 10 is relatively heavily worn (worn over 8006 m), and the comparison means 82 generates a blade wear signal. Step n-102 then proceeds to step n-103, where a blade wear signal is sent to the display means 84, and the display means 84 is energized based on the blade wear signal, so that the display means 84 indicates that the blade 10 is Indicates relatively large wear.

The above-mentioned state can be canceled by operating a reset switch (not shown) after replacing the worn blade IO with a new one.

Although a specific example of the blade defect detection device according to the present invention has been described above, the present invention is not limited to this specific example, and various modifications and changes can be made without departing from the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a part of a processing device equipped with a specific example of the blade defect detection device according to the present invention. FIG. 2 is a diagram showing the rotary processing tool and its vicinity of the processing apparatus shown in FIG. 1, viewed from the back. FIG. 3 is a plan view showing the rotary processing tool and its vicinity. FIG. 4 is a block diagram showing the main parts of the blade defect detection device shown in FIG. 1. 5' is a flowchart illustrating blade failure detection by the blade failure detection means in the blade failure detection device of FIG. 4; FIG. FIG. 6 is a flowchart illustrating blade wear detection by the blade defect detection bag W of FIG. 4 and the blade wear defect detection means in the company. 2... Processing tool assembly 4... Holding tool assembly 8... Drive source 10... Blade 16... Processing liquid supply means 28... Semiconductor wafer 30... Light projecting means 32. ...Light receiving means 50...Gas supply pipe 54...Blade damage detection means 56...Blade wear detection means 58...Maximum value holding means 60...Minimum value holding means 68...Pulse Signal generation means 74...Counting means 80...Low frequency passing means FIG.

Claims (1)

[Scope of Claims] 1. Optical detection means comprising a light projecting means for projecting light toward the peripheral edge of a blade that processes a workpiece, and a light receiving means for receiving light from the light projecting means. , a detection device for detecting a defective blade based on an output signal from the light receiving means, comprising: a maximum value holding means for holding a maximum value (M) of the output signal from the light receiving means; and an output signal from the light receiving means. a minimum value holding means for holding the minimum value (m) of the maximum value holding means, and a difference (M) between the maximum value (M) held by the maximum value holding means and the minimum value (m) held by the minimum value holding means; -m)
and a set reference value (V_0); m)>V_0
] Pulse signal generation means that sometimes generates a pulse signal; Fault signal generation means that generates a faulty signal in relation to the pulse signal from the pulse signal generation means; Faulty signal counting means that counts the faulty signals; , during the blade defect detection operation, the maximum value (M) held in the maximum value holding means and the minimum value held by the comparison means are determined at every first set time (T_1) interval. A comparison is performed between the difference (M-m) of the minimum value (m) held in the means and the set reference value (V_0), and the pulse signal generating means continuously generates the pulse signal. The defective signal is generated when the defective signal is generated, and the defective signal counting means generates a blade breakage signal when the defective signal exceeds a predetermined number within a second set time (T_2). Detection device. 2. The defective signal generating means converts the frequency of the interval of the pulse signal generated by the pulse signal generating means, and generates the defective signal when the frequency of the pulse signal is within a predetermined range. 1. The detection device according to 1. 3. The detection device according to claim 1 or 2, wherein the first set time (T_1) is a time required for the blade to make substantially one revolution. 4. Optical detection means consisting of a light projecting means for projecting light toward the peripheral edge of the blade that processes the workpiece, and a light receiving means for receiving the light from the light projecting means; A detection device for detecting blade defects based on an output signal, comprising: low frequency passing means for passing only low frequency signals; and comparison means for comparing the signal from the low frequency passing means with a set reference value; an output signal from the light receiving means is fed through the low frequency passing means to the comparing means, the comparing means generating a blade wear signal when a signal value from the low frequency passing means exceeds the set reference value; A detection device characterized by: