JP2002333309A - Apparatus and method for measuring chipping - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chipping measuring apparatus and method permitting continuous measurement at a high speed. SOLUTION: In the chipping measuring apparatus for measuring the chipping state of a kerf formed on a workpiece cut by a high speed rotating blade, the chipping state of the kerf is measured with the chipping measuring apparatus characterized in that it has a light emitting device for irradiating slit-like light over a width wider than that of a standard kerf without producing at least chipping for the prescribed area of a finished face including the kerf, a light receiving device for receiving reflection light from the finished face, and a chipping judging device for judging the chipping state of the kerf in response to an amount of receiving light by the light receiving device. Furthermore, a receiving light amount data A/D converting the amount of the receiving light with a prescribed sampling frequency by the chipping judging device is compared with a reference receiving light amount to preferably perform the abnormal judgement of the chipping state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for measuring chipping, and more particularly to an apparatus and method for measuring chipping that can determine chipping that occurs in a kerf of a workpiece.

[0002]

2. Description of the Related Art In a dicing process for dividing a workpiece such as a semiconductor wafer into individual chips, cutting is performed using a ring-shaped blade rotating at high speed, and a kerf (cut) is formed along a street between semiconductor chips. Grooves) are formed.

At this time, chipping, which is irregular breaking of the edge of the kerf, may occur due to breakage, clogging, wear, etc. of the blade heated to a high temperature due to frictional heat. If the chipping is large enough to reach the outside of the street of the semiconductor wafer, the semiconductor element is destroyed and the yield is reduced.

Therefore, in order to prevent the occurrence of excessive chipping, the state of chipping is measured by observing the condition of the kerf at any time, and the occurrence of chipping is measured and grasped. Actions such as replacing a damaged or worn blade are performed.

Conventionally, as a method of observing the state of the kerf and measuring chipping, a method of visually observing the kerf using a microscope, a method of capturing an image of a processed surface with a CCD camera installed in a fully automatic dicer and performing image processing, and the like. Is common.

[0006]

However, in the above-mentioned conventional measuring method, the range of an image obtained by one measurement is narrow and a plurality of measurements are required. There is a problem that the measuring speed is very slow because it takes time to adjust.

Further, in the conventional method, since a narrow area on a processing surface can be measured only in a spot-like manner, there is a problem that measurement data is discontinuous. Therefore, the extraction information is insufficient, and it is not possible to sufficiently grasp the state of occurrence of chipping or analyze data.

Further, in the conventional method of imaging a processed surface with a CCD camera and performing image processing, there is a problem that chipping measurement data is two-dimensional data, wasteful data is required, and data processing and analysis take time.

The present invention has been made in view of the above problems of the conventional chipping measuring device and method, and
SUMMARY OF THE INVENTION It is an object of the present invention to provide a new and improved chipping measurement device and method capable of high-speed and continuous measurement.

[0010]

According to the present invention, there is provided a chipping measuring method for measuring a chipping state of a kerf formed on a workpiece cut by a high-speed rotating blade. A step of irradiating a predetermined area of the processing surface including the kerf with slit-shaped light over a width at least wider than the width of the standard kerf in which chipping does not occur;
There is provided a chipping measurement method including a step of receiving light reflected from a processing surface and a step of determining a chipping state of a kerf according to an amount of light received by a light receiving device.

With this configuration, the measurement speed is much higher than that of the conventional measurement method, and the measurement speed does not decrease even when the number of chipping measurement points increases. Further, since the measurement data is continuous along the kerf, the chipping state can be grasped in detail with sufficient measurement data, and a sudden cutting abnormality can be detected.

If the step of determining the chipping state is configured to include a step of comparing the received light amount, which is an actually measured value, with a reference received light amount to determine whether the chipping state is abnormal, the predetermined reference received light amount is determined. As a criterion, it is easy to judge whether the chipping state is abnormal or normal, and it is possible to make an objective and quick judgment.

Further, if the reference light receiving amount is configured to be determined by actually measuring the light receiving amount from the processed surface on which the standard kerf is formed, the reference light receiving amount having high reliability based on the actually measured value is obtained. can get.

Further, if the reference light receiving amount is calculated based on the width of the standard kerf and the irradiation width of the slit light, the reference light receiving amount having high versatility can be set relatively easily.

Further, in the step of judging the chipping state, the chipping judging device performs A / D conversion of the amount of light received by the light receiving device at a predetermined sampling frequency to generate the amount of received light. If it is configured to include a step of automatically performing an abnormality determination of the chipping state in comparison with the received light amount, since the received light amount data is one-dimensional data, data processing and analysis can be performed quickly and easily. it can. In addition, since the determination of the chipping state is performed automatically, labor saving can be achieved.

Further, in a chipping measuring apparatus for measuring a chipping state of a kerf formed on a workpiece cut by a high-speed rotating blade, at least chipping does not occur in a predetermined region of a processing surface including the kerf. A light emitting device that irradiates slit-like light over a width wider than the standard kerf, a light receiving device that receives light reflected from the processed surface, and a chipping determination device that determines the chipping state of the kerf according to the amount of light received by the light receiving device And a chipping measurement device characterized by comprising:

With such a configuration, it is possible to provide a chipping measuring apparatus that easily realizes the above-described chipping measuring method.

Further, the above-mentioned chipping judging device converts the amount of light received by the light receiving device into an A / D signal at a predetermined sampling frequency.
A step of judging the above-mentioned chipping state by comprising a data converting means for converting the received light quantity data into a received light quantity data and a judging means for judging an abnormality of the chipping state by comparing the received light quantity data with the reference light receiving quantity; Can be provided with a chipping measurement device provided with a chipping determination device that easily realizes.

Further, if the reference light receiving amount is determined by actually measuring the light receiving amount from the processing surface on which the standard kerf is formed, a highly reliable reference light receiving amount can be provided to the chipping determination device. it can.

Further, if the reference light receiving amount is configured to be calculated based on the width of the standard kerf and the irradiation width of the slit-like light, the above-mentioned chipping judging device can easily provide a general reference light receiving amount.

Further, the chipping measuring device is provided in the dicing device, and if the measured chipping state of the kerf can be fed back to the cutting conditions of the dicing device or blade replacement, information on the measured chipping state can be obtained. Can be accurately and promptly reflected on cutting conditions and blade replacement in the cutting of the dicing apparatus.
Therefore, the processing quality of the workpiece is improved and the yield is increased.

[0022]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A preferred embodiment of the present invention will be described in detail. In the specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

A case where the chipping measuring device according to the embodiment of the present invention is installed in a dicing device will be described in detail below, but the present invention is not limited to such an example.

First, an outline of a dicing apparatus provided with a chipping measuring apparatus according to the present embodiment will be described with reference to FIG. FIG. 1 is an overall perspective view of a dicing device provided with a chipping measurement device according to the present embodiment.

As shown in FIG. 1, a dicing apparatus main body 1
0 has a cutting unit 20 for cutting or cutting the semiconductor wafer 12, a chuck table 15 on which the semiconductor wafer 12 is mounted, and a chipping measuring device 40 for measuring the chipping state of the kerf.

The chuck table 15 holds the wafer tape 1
3, the semiconductor wafer 12 supported by the frame 14 is placed, and is relatively movable in the horizontal direction with respect to the cutting unit 20 or the chipping measuring device 40.

The cutting unit 20 cuts or cuts the semiconductor wafer 12 at a predetermined cutting depth. Is performed. After cutting, the cutting chips, cutting water and the like are washed by a washing Mach nozzle (not shown) or the like, and then transferred below the chipping measuring device 40 to measure the chipping state. After the measurement, it is transported below the cutting unit 20 and cut again.

Next, a cutting method by the cutting unit 20 in the present embodiment will be described with reference to FIG.
FIG. 2 is a perspective view showing a main part and a processing surface of the cutting unit 20 according to the present embodiment.

As shown in FIG. 2, the cutting unit 20 is provided with a ring-shaped blade 22 and a flange 24 for holding the blade 22 from both sides. In addition, for example, a cutting water supply unit such as a shower nozzle and a side nozzle, and a device such as a foil cover are not shown.

The blade 22 is formed into a ring shape by electrodepositing abrasive grains such as diamond with a bonding material such as nickel. The thickness of the blade 22 is extremely thin.
0 μm. The blade 22 is mounted on a spindle rotating shaft while being clamped by a flange 24.
High-speed rotation is possible at rpm. During cutting, cutting water is supplied by, for example, a shower nozzle or a side nozzle.
The blade 22 and the processing point are cooled.

The flange 24 is made of a relatively hard metal such as stainless steel, for example, and holds the blade 22 from both sides. At this time, the flange 2
The blade 4 can clamp substantially the same area from both sides of the blade 22 with a uniform pressure, so that the processing surface can be cut substantially linearly without the blade 22 being bent or deformed by the partial pressure.

The cutting unit 20 having the above structure is movable relative to the chuck table 15 on which the semiconductor wafer 12 shown in FIG. 1 is mounted. In this embodiment,
The cutting proceeds by moving the chuck table 15 with respect to the fixed cutting unit 20. On the other hand, there are cases where the chuck table 15 is fixed and the cutting unit 20 moves to perform cutting. The moving speed of the chuck table 15, that is, the cutting speed is, for example, about 70 mm / s.

As shown in FIG. 2, the blade 22 rotating at a high speed is cut into a street 2 between the semiconductor chips 27 while cutting the outer periphery of the blade 22 into a processing surface of the semiconductor wafer 12 by a predetermined amount.
6, and relatively cut in the horizontal direction (X direction in FIG. 2). At this time, in the present embodiment, the rotation direction of the blade 22 is the clockwise direction in FIG. 2, and the down cutting method is such that the cutting edge of the rotating blade 22 bites into the inside from the upper surface (working surface) of the workpiece. Is used.

Next, the state of occurrence of chipping will be described with reference to FIG. FIG. 3 is a schematic diagram showing the state of occurrence of chipping.

As shown in FIG. 3, an extremely thin kerf (cut groove) 28 is formed on the street 26 cut by the blade 22. At this time, it is ideal that a standard kerf 32 (shown by a dotted line in FIG. 3) is formed such that both edges of the kerf are substantially straight lines substantially parallel to the street 26. However,
In actual cutting, chippings 30, which are irregular breaks, occur at both edges of the kerf 28, and both edges of the kerf 28 are non-linear. If the chipping 30 ′ is large enough to reach the outside of the street 26, the semiconductor chip 27
Is destroyed and becomes a defective product, and the yield decreases.

The cause of the chipping 30 is that the blade 22 heated to a high temperature due to frictional heat is not sufficiently cooled by the cutting water, and is clogged, worn, bent, and broken. Therefore, by using the chipping measuring device according to the present embodiment to measure and grasp the state of the chipping 30 on the machined surface, it is possible to take measures such as changing cutting conditions and replacing blades, thereby causing excessive chipping. Can be prevented beforehand.

Next, an outline of the chipping measuring device 40 in the present embodiment will be described with reference to FIG. FIG. 4 is a schematic diagram of the chipping measurement device 40 according to the present embodiment.

As shown in FIG.
0 is a light emitting device 4 for irradiating slit-like light to the processing surface
2, a light receiving device 44 for receiving light reflected from the processing surface,
A chipping determination device that determines the chipping state of the calf based on the amount of received light.

The light emitting device 42 is disposed above the processing surface, and irradiates the processing surface with slit light at a predetermined incident angle. The incident light has a width that is at least wider than the standard kerf 32 in a direction substantially perpendicular to the street 26, and is irradiated over a range including the entire kerf 28.

The light receiving device 44 is disposed above the processing surface so as to face the light emitting device 42, receives the reflected light of the incident light emitted by the light emitting device 42 on the processing surface, and measures the amount of received light. It should be noted that the incident angle of the incident light on the processing surface and the reflection angle of the reflected light are substantially the same, and the shape and arrangement of the light receiving device 44 are adjusted so that light other than the reflected light on the processing surface is received as little as possible. It is that you are.

Further, the chipping judgment device 46 has a data conversion means 46a and a judgment means 46b. The data converter 46a has, for example, an A / D converter and a recording medium such as a magnetic disk. Data conversion means 4
6a performs A / D conversion of the received light amount measured by the light receiving device 44 at a predetermined sampling frequency to create and record received light amount data. On the other hand, the determination unit 46b determines the chipping state using the received light amount data supplied by the data conversion unit 46a. This determination method will be described later in detail.

Next, the mechanism by which the chipping measuring device 40 measures the kerf chipping using the amount of received light will be described in detail with reference to FIG. FIG. 5 is a conceptual diagram showing the amount of received light that changes according to the chipping state.
In FIG. 5, an arrow extending downward and reaching the processing surface indicates the direction of incident light, and an arrow extending upward and extending from the processing surface indicates the direction of reflected light.

As shown in FIG. 5, the kerf 28 on the processing surface
On both edges, chipping 30 of various sizes by cutting
Occurs, and the width of the kerf 28 changes depending on the size of the chipping. The slit-shaped incident light is specularly reflected on the processing surface outside the kerf 28 and goes to the light receiving device 44 as reflected light, but reaches the inside of the kerf 28 inside the kerf 28 and does not go to the light receiving device 44 because it is not regularly reflected. . The reason that the incident light that reaches the calf 28 does not reflect regularly is as follows.
The bottom surface of the kerf 28 is often made substantially non-planar by cutting, so that, for example, incident light is irregularly reflected or absorbed. Even if specular reflection occurs, the reflection point shifts by the depth of the kerf 28, and the light receiving device 4
I do not go to 4.

Here, in order to explain the difference in the amount of received light according to the magnitude of chipping, the incident light and the reflected light at the measurement locations A and B shown in FIG. Note that the irradiation width of the incident light is S, and the widths of the kerfs 28 at the measurement locations A and B are H (a) and H (b), respectively.

First, no chipping occurs at the measurement location A, and the width of the kerf 28 is substantially the same as the width of the standard kerf 32. Therefore, since a relatively large number of processed surfaces are not cut in the street, a relatively large amount of incident light is regularly reflected on the processed surface. The ratio between the amount of incident light and the amount of reflected light is about S: {S−H (a)}. In FIG. 5, for convenience, if incident light having a light quantity of 10 arrows is incident, it is shown that reflected light of the light quantity of 8 arrows is reflected.

On the other hand, at the measurement location B, relatively large chipping 30 occurs, and the width of the kerf 28 is considerably larger than the width of the standard kerf 32. Therefore, since the width of the kerf 28 occupying the street is relatively large, the incident light that is specularly reflected on the processing surface is relatively small.
The ratio between the amount of incident light and the amount of reflected light is approximately S: {SH (b)}
It is. As shown in FIG. 5, as in the case of the measurement place A, for convenience, if incident light of the light quantity of ten arrows is incident, reflected light of the light quantity of four arrows is reflected. Very little compared to A.

As described above, the width of the kerf 28, that is, the magnitude of chipping, and the amount of reflected light have a direct proportional correlation. Therefore, the magnitude of chipping can be grasped by receiving the reflected light by the light receiving device 44 and measuring the amount of received light.

Next, continuous measurement of the chipping state along the kerf 28 will be described. First, the semiconductor wafer 12 is horizontally moved in a direction substantially parallel to the street 26 while the irradiation of the slit-shaped light by the light emitting device 42 and the light reception by the light receiving device 44 are performed. As a result, the area of the processing surface irradiated with the slit-shaped light also
6, and the incident light continues to be reflected continuously. At this time, since the magnitude of the chipping generated on the kerf 28 changes depending on the measurement position (that is, the reflection position),
The amount of light reflected regularly on the processing surface increases or decreases. Therefore, the amount of light received by the light receiving device 44 also increases or decreases depending on the measurement position. By continuously irradiating and receiving the slit-shaped light while moving the semiconductor wafer 12 in this manner, the amount of continuous light received along the kerf 28 is measured.

Next, data processing of the amount of received light by the data conversion means 46a of the chipping determination device 46 will be described.

Since the continuous light reception amount is analog data, the data conversion means 46 of the chipping determination device 46
The data is A / D converted by a and continuously recorded as received light amount data which is digital data. At this time, it is also possible to transmit the received light amount data as necessary and to display a change in the received light amount data on a display or the like, for example.

FIG. 6 is a graph showing received light amount data along the kerf 28. The horizontal axis in FIG. 6 is the measurement position, and the vertical axis is the amount of received light.

As shown in FIG. 6, the received light amount data increases and decreases depending on the measurement position, which indicates that the magnitude of chipping differs depending on the measurement position. As described above, the generated chipping is small at the measurement position where the received light amount data is large, while the generated chipping is large at the measurement position where the received light amount is small.

Since there is an inverse relationship between the sampling frequency of the received light amount data and the measurement interval △, the A / D
The measurement interval △ can be easily adjusted by increasing or decreasing the sampling frequency during conversion. Therefore, by increasing the sampling frequency considerably, very detailed continuous received light amount data can be obtained. Note that even if the measurement interval △ is made very small and the number of measurement points is increased, the measurement speed does not decrease, which is useful.

FIG. 6 further shows the reference light receiving amount and the allowable light receiving amount. Hereinafter, the reference light receiving amount and the allowable light receiving amount will be described in detail.

The reference light receiving amount is a light receiving amount obtained when measuring the standard kerf 32 in which chipping does not occur. In FIG. 6, the light receiving amount is substantially the maximum value. The allowable light receiving amount is calculated by discounting the reference light receiving amount at a predetermined rate, and is a lower limit value of the light receiving amount within a range in which the magnitude of chipping is allowable.

As a method for determining the reference light receiving amount, a method for actually measuring the light receiving amount from the processing surface on which the standard kerf 32 is formed, and a method for determining the width of the standard kerf 32 and the irradiation width S of the slit-like light are used. There are two methods of calculation based on the calculation.

First, a method of actually measuring the reference light receiving amount from the processing surface on which the standard kerf 32 is formed will be described. First, the machined surface is cut so that chipping does not occur as much as possible to form a kerf 28 having a shape close to an ideal standard kerf 32. Next, a suitable measurement position where chipping does not occur on the kerf 28 is detected using, for example, a microscope or the like, and the position of the chipping measurement device 40 is adjusted. Thereafter, the reference light receiving amount is determined by irradiating the measurement position with slit-like light and measuring the received light amount.

Further, instead of measuring the amount of received light at a specific measurement position as described above, the light is continuously or spot-wise over a predetermined range along the kerf 28 formed in a shape close to the standard kerf 32. The received light amount may be measured, and the average value thereof may be used as the reference received light amount.

Next, a method of calculating the reference light receiving amount based on the width of the standard kerf 32 and the irradiation width S of the slit light will be described. First, slit light is irradiated with a predetermined irradiation width S along the street 26 of the semiconductor wafer 12 before cutting, and the reflected light is received to measure the received light amount (total received light amount). At this time, since no kerf is formed on the street 26, almost all of the incident light is specularly reflected on the processed surface and received. Next, the reference light receiving amount is determined by subtracting the light receiving amount for irradiating the standard kerf 32 from the total light receiving amount. Specifically, assuming that the ratio of the standard kerf 32 width N to the irradiation width S multiplied by the total received light amount T is the received light amount K for irradiating the standard kerf 32, the reference received light amount Q
Is represented by the formula Q = TK = T × {1- (N / S)}. The width of the standard kerf 32 is empirically set from past cutting examples and the like based on the thickness of the blade 22 and the characteristics of the workpiece.

As described above, the reference received light amount can be determined by actual measurement or theoretical calculation. However, there is a possibility that a slight error may occur by any of the methods. It is preferable to make appropriate corrections.

Subsequently, the allowable light receiving amount is determined by discounting the reference light receiving amount set as described above at a predetermined rate.
This discount rate is set in consideration of, for example, the width of the street 26, the width of the standard kerf 32, the irradiation width S of incident light, the product yield, and the like.

If the allowable light receiving amount is set too large, it is determined that even a small amount of chipping is abnormal. Conversely, if the allowable light receiving amount is set too small, it is determined that there is an abnormality even if chipping is large enough to impair product quality. There is a problem that is not done. Therefore, at the time of initial setting of the permissible received light amount, not only is it theoretically calculated from the reference received light amount, but also the amount of chipping at a plurality of measurement positions and the measured received light amount are sufficiently compared to determine Must be set.

Next, the determination of the chipping state by the determination means 46b of the chipping determination device 46 will be described in detail.

Determination means 46b of chipping determination device 46
Is input with the reference light receiving amount and the allowable light receiving amount determined as described above, and performs automatic judgment by comparing the data with the actually measured light receiving amount data. The determination means 46b is controlled by, for example, a program or the like.
The result of numerical analysis of the received light amount data input from a
It is determined whether the set condition is satisfied.

First, as a basic setting condition, a setting condition in which measured light receiving amount data is simply compared with the allowable light receiving amount is preferable. In the case of this setting condition, if the measured light receiving amount data is larger than the allowable light receiving amount, the magnitude of the chipping is such that the processing quality of the product is not hindered, and it is determined that the product is normal. On the other hand, if the received light amount data is smaller than the permissible received light amount, it is determined that excessive chipping has occurred and is abnormal. When the abnormality is determined in this manner, there is a possibility of abnormal cutting such as chipping reaching the outside of the street 26 and destroying the semiconductor element.

Even if the amount of light received that falls below the permissible received light amount is not measured, even when the received light amount decreases as a whole and approaches the permissible received light amount, relatively large chipping frequently occurs. May have been affected.
Therefore, the above-described case can also be detected by adding a setting condition such that, for example, if the average of the received light amount data over a predetermined region is a value larger than the allowable received light amount by a predetermined amount, the determination means 46b determines an abnormality.

Further, when the entire amount of received light periodically increases or decreases, it is considered that the reflected light reflects the damage of the blade 22 or the curvature of the kerf 28. In this case, a setting condition for detecting the periodicity may be added to the condition setting of the determination means 46b.

As described above, it is possible to judge various received light amount data, that is, a chipping state, depending on the setting condition of the judgment means 46b. If the result of the determination by the determination means 46b is an abnormality determination, it is preferable that a warning be automatically sent to the operator by, for example, a buzzer or a display.

As described above, in the chipping measurement device 40 according to the present embodiment, normality or abnormality can be determined only by comparing the magnitude of the measured light reception amount with the allowable light reception amount. The size of chipping on the surface can be determined, and the chipping state can be grasped.

Further, by adding to the chipping judging device 46 a setting condition for judging an abnormality other than the above, it is possible to cope with various chipping states.

Further, the received light amount data according to the present embodiment is one-dimensional data, and the number of data is smaller than that of two-dimensional data obtained by a conventional measuring method, so that high-speed data processing is possible. Therefore, the distribution and maximum value of chipping,
Parameters such as minimum value and average value can be calculated.
Analysis of chipping becomes easy. Further, since continuous measurement data is obtained along the kerf 28, minute sections and sudden chippings can be grasped, and the chipping state can be sufficiently grasped without overlooking the abnormal cutting position.

The measuring speed of the chipping measuring device 40 according to the present embodiment is very high. This measuring speed depends on the moving speed of the workpiece with respect to the chipping measuring device 40. For example, when the workpiece is moved at about 300 mm / s with the chipping measurement device fixed, the measurement speed is also about 300 mm / s, and one street of an 8-inch semiconductor wafer can be measured within about 1 second. , Which is several tens of times faster than conventional measurement methods.

In the present embodiment, since the chipping measuring device 40 is installed at a position separated from the cutting unit 20, the semiconductor wafer 12 cut by the cutting unit 20 is transferred to the installation position of the chipping measuring device 40. Then, the measurement is performed. However, in order to further improve the measurement efficiency, for example, the chipping measuring device 40 and a cleaning unit such as a cleaning Mach nozzle may be disposed behind the cutting unit 20 in the cutting direction.

With this configuration, one of the semiconductor wafers 12
After cutting two streets, it is possible to perform measurement after blowing off cutting chips and cutting water on the processing surface at the same position. Thereby, the semiconductor wafer 1
Since the time required for transfer of No. 2 can be omitted, more efficient measurement and repetition of cutting can be performed.

In order to further improve the efficiency, the semiconductor wafer 1
Simultaneously with the cutting of No. 2, cleaning by a Mach nozzle or the like and measurement of chipping by the chipping measuring device 40 may be performed behind the cutting direction. This makes it possible to determine the chipping state in real time during cutting,
Not only can the required time be shortened, but also the measurement results can be quickly reflected in the cutting conditions.

Next, a measuring method using the chipping measuring device 40 according to the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing each step of the measuring method using the chipping measuring device 40 according to the present embodiment.

First, in step S100, the semiconductor wafer 12 is cut (step S100). The semiconductor wafer 12 mounted on the chuck table 15 is cut by a high-speed rotating blade 22 installed in a cutting unit 20 of the dicing apparatus body 10. Cutting is performed over a predetermined number of streets 26. A kerf 28 is formed on the processing surface along the street 26 by cutting, and at this time, chipping may occur at the edge of the kerf 28.

Next, in step S102, the semiconductor wafer 12 is transferred (step S102). The semiconductor wafer 12 is placed on the chuck table 15,
It is transported from the vicinity of the cutting unit 20 to below the installation position of the chipping measurement device 40. The present invention is not limited to such an example, and as described above, the chipping measuring device 40 can be installed near the cutting unit 20 and the transfer time required for this step can be omitted.

Further, in step S104, the semiconductor wafer 12 is cleaned (step S104). For example, using a cleaning Mach nozzle or the like, cleaning is performed by blowing off cutting chips, cutting water and the like deposited on the processing surface of the semiconductor wafer 12. The reason for this cleaning is that if the above-mentioned cutting chips or cutting water remains on a substantially smooth machined surface, the light irradiated in the subsequent process will impinge on these remaining objects and reflect irregularly, so that an accurate amount of received light cannot be obtained. Because. This step is performed in step S102.
May be performed before the semiconductor wafer 12 is transferred.

Thereafter, in step S106, the positions of the chipping measuring device 40 and the semiconductor wafer 12 are adjusted (step S106). More specifically, the chuck table 15 is so arranged that the slit-shaped light emitted from the light emitting device 42 to the processing surface in a later step includes the kerf 28 to be measured.
Fine-tune the position of. At this time, the position is adjusted so that the center of the slit-shaped light and the center of the kerf 28 are substantially at the same position.
Even if the measurement proceeds, the kerf 28 must be kept out of the irradiation range of the slit light. Note that it is preferable to adjust the position so that the slit-shaped light starts to be irradiated from the vicinity of the end of the semiconductor wafer 12.

Next, in step S108, the processing surface is irradiated with slit light from the light emitting device 42 (step S108). Slit light having an irradiation width S wider than the width of the standard kerf 32 is emitted from the light emitting device 42 to the semiconductor wafer 1.
2. Irradiation is applied to the calf 28 on the machining surface and its vicinity,
The light enters the processing surface at a predetermined incident angle. The incident light is specularly reflected on the processing surface outside the kerf 28 and travels toward the light receiving device 44.
The light does not go to the light receiving device 44 due to irregular reflection or absorption inside the calf 28.

In step S110, the reflected light is received by the light receiving device 44 (step S110).
In step S108, the light receiving device 44 receives the reflected light that is irradiated onto the processing surface and is specularly reflected at the processing surfaces on both sides of the kerf 28 at a reflection angle substantially equal to the incident angle. Since the amount of reflected light is smaller than the amount of incident light by the width of the kerf 28, the amount of received light is smaller than the amount of irradiated light.

Thereafter, in step S112, the kerf 2
8 is measured (step S11).
2). Chuck table 1 on which semiconductor wafer 12 is placed
By moving 5 horizontally, the irradiation position of the slit light on the processing surface moves along the kerf 28. As a result, the amount of received light is continuously measured along the kerf 28. At this time, if chipping has occurred in the kerf 28, the amount of received light decreases in proportion to the size of the chipping.

Next, in step S114, the received light amount is subjected to data processing by the chipping determining device 46 (step S114). The received light amount continuously measured in step S112 is A / D-converted by the data processing means 46a of the chipping determining device 46, and is recorded as received light amount data which is one-dimensional digital data. At this time, the measurement interval can be easily adjusted by adjusting the sampling frequency of the received light amount data. Therefore, the number of measurement points can be increased without lowering the measurement speed.

Thereafter, in step S116, the chipping state of the kerf 28 is determined by the chipping determination device 46 (step S116). The received light amount data obtained in step S114 reflects the magnitude of chipping generated in the kerf 28, and the smaller the received light amount data, the greater the chipping. Therefore, the chipping state can be determined by comparing the magnitude of the allowable light receiving amount based on the reference light receiving amount with the measured light receiving amount data.

As described above, the reference light receiving amount is substantially the same as the light receiving amount when the standard kerf 32 in which chipping does not occur is measured. The method of setting the reference light receiving amount includes a method of actually measuring the light receiving amount from the processing surface on which the standard kerf 32 is formed, and a method of calculating based on the width of the standard kerf 32 and the irradiation width S of the slit light. is there.

The allowable light receiving amount is a light receiving amount calculated by discounting the reference light receiving amount at a predetermined rate, and is a substantially lower limit of the light receiving amount within a range in which the magnitude of chipping can be tolerated.

As described above, after the reference light receiving amount and the allowable light receiving amount are determined, the allowable light receiving amount and the measured light receiving amount data are sequentially compared for each measurement position, and the abnormality is automatically determined. If the measured light receiving amount data is equal to or larger than the allowable light receiving amount, the magnitude of chipping is such that the processing quality of the product is not hindered, and is determined to be normal. On the other hand, if the measured light receiving amount data is less than the allowable light receiving amount, there is a possibility that excessive chipping may occur so as to hinder processing deterioration of the product, and it is determined that the product is abnormal.

In addition to the above, various chipping states can be automatically detected by adding a setting condition for determining an abnormality to the chipping determination device 46.

Further, the continuously measured light receiving amount data is displayed on, for example, a display or the like, and the global tendency or periodicity of the light receiving amount data is analyzed to determine the chipping state from various viewpoints. can do.

Next, in step S118, the result of determination of the chipping state is fed back to cutting (step S118). When it is determined that the chipping state is good as a result of the determination by the chipping determination device 46 in step S116, it is determined that the cutting is continued. On the other hand, when it is determined that the chipping state is defective, it is determined that a measure such as a change in cutting conditions or replacement of the blade 22 is performed.

For example, when relatively large chipping occurs frequently, cutting conditions such as a decrease in cutting water temperature and an increase in cutting water amount are changed, and measures are taken to smoothly carry out subsequent cutting. You. Further, for example, when the chipping tends to increase as a whole, it is possible that the blade 22 is being worn out, which can evoke the need to replace the blade 22.

Since the chipping measurement method according to the present embodiment enables continuous high-speed measurement, feedback of the measurement result to cutting can be performed more accurately and promptly as compared with the related art.

Further, by further improving the present embodiment, the chipping measuring device is arranged behind the cutting unit in the cutting direction.
If chipping can be measured simultaneously with cutting, better feedback is possible. In this case, since the chipping state can be grasped in real time during the cutting, the cutting can be stopped or the cutting conditions can be changed immediately when a cutting abnormality occurs, which is very useful for increasing the yield.

Next, in step S120, the semiconductor wafer 12 is transferred again (step S120). The semiconductor wafer 12 having completed the measurement of the predetermined area is transferred from the vicinity of the chipping measuring device 40 to the vicinity of the cutting unit 20. As described above, this step can be omitted by installing the chipping measuring device 40 near the cutting unit 20.

Finally, in step S122, the semiconductor wafer 12 is cut again (step S122). Also in this step, the cutting of the semiconductor wafer 12 is performed over a predetermined number of streets 26. In step 118, since the chipping measurement result is fed back and the cutting conditions and the like are suitably set, smooth cutting is possible and high-precision cutting is possible.

The preferred embodiment of the present invention has been described with reference to the accompanying drawings, but the present invention is not limited to this example. It is clear that a person skilled in the art can conceive various changes or modifications within the scope of the technical idea described in the claims, and those modifications naturally fall within the technical scope of the present invention. It is understood to belong.

For example, although the case where the chipping measuring device 40 according to the present embodiment is installed in a dicing device has been described, the present invention is not limited to such an example. The device in which the chipping measuring device according to the present invention is installed may be a cutting device or the like that cuts a workpiece by a high-speed rotating blade and forms a kerf (cut groove) on a processing surface. Further, the chipping measurement device according to the present invention may be configured independently and used as a dedicated measurement device.

Further, the chipping measuring device 40 according to the present embodiment is installed at a position away from the cutting unit 20 as shown in FIG. 1, but the present invention is not limited to this example. For example, the chipping measuring device 40 may be arranged near the cutting unit 20 to eliminate the step of transferring the semiconductor wafer 12 to improve efficiency. Further, the measurement of the chipping state of the kerf 28 and the cutting of the processing surface may be performed simultaneously.

In this embodiment, the chipping measurement device 40 is fixed and the semiconductor wafer 12
Was moved, but the present invention is not limited to such an example. It is sufficient that the chipping measurement device 40 can move relative to the semiconductor wafer. For example, the semiconductor wafer 12 may be fixed and the light emitting device 42 and the light receiving device 44 of the chipping measurement device 40 may be moved.

Further, the chipping measuring device 40 according to the present embodiment is provided with one set of the light emitting device 42 and the light receiving device 44. However, the present invention is not limited to this example. May be installed above both sides of the calf for more detailed measurements. Further, a plurality of sets of light emitting devices and light receiving devices may be arranged in parallel so that a plurality of kerfs can be measured simultaneously.

In the present embodiment, the down cutting method is used as the cutting method using the blade 22. However, the present invention is not limited to such an example. An up-cut method may be employed in which the cutting edge bites into the inside of the workpiece from the lower surface.

The workpiece to be cut is not limited to the semiconductor wafer 12, but may be a magnetic head such as a VTR or FDD, ceramic, quartz, glass, small electronic parts, a piezoelectric crystal material represented by lithium niobate, or the like. It can also be applied to brittle materials such as ferrite.

Although the blade 22 according to the present embodiment is ring-shaped, the present invention is not limited to this example, and may be, for example, a hub blade integrally formed with a hub (Hub) and a cutting blade. .

[0105]

As described above, according to the apparatus and method for measuring chipping according to the present invention, it is possible to measure the state of chipping along a kerf at a very high speed, and even if the number of measurement points increases. The measurement speed does not decrease.

Further, since continuous measurement data can be obtained along the kerf, it is easy to grasp the general chipping tendency and chipping state such as periodicity, and it is also possible to detect sudden cutting abnormalities. It is.

In addition, the measurement data is one-dimensional data, and processing and analysis of the measurement data can be performed quickly and easily.

Further, it is easy to judge whether the chipping state is abnormal or normal with reference to a predetermined reference light receiving amount, and objective and quick judgment is possible.

Further, information on the measured chipping state can be accurately and promptly fed back to cutting conditions and blade replacement in the cutting of the dicing apparatus. Therefore, the processing quality of the workpiece is improved and the yield is increased.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a dicing apparatus provided with a chipping measurement device according to an embodiment.

FIG. 2 is a perspective view showing a main part and a processing surface of the cutting unit 20 according to the embodiment.

FIG. 3 is a schematic diagram showing a state of occurrence of chipping.

FIG. 4 is a schematic diagram of a chipping measurement device according to the present embodiment.

FIG. 5 is a conceptual diagram illustrating a light receiving amount that changes according to a chipping state.

FIG. 6 is a graph showing received light amount data along a kerf.

FIG. 7 is a flowchart showing each step of the chipping measurement method according to the embodiment.

[Explanation of symbols]

 10: Dicing device body 12: Semiconductor wafer 20: Cutting unit 22: Blade 26: Street 28: Calf 30: Chipping 32: Standard kerf 40: Chipping measuring device 42: Light emitting device 44: Light receiving device 46: Chipping determining device

Claims (5)

[Claims] 1. A chipping measuring method for measuring a chipping state of a kerf formed on a workpiece cut by a high-speed rotating blade, wherein at least a chipping is performed on a predetermined area of a processing surface including the kerf by a light emitting device. A step of irradiating slit-like light over a width wider than the width of the standard kerf in which no light is generated; a step of receiving light reflected from the processing surface by a light receiving device; Determining a chipping state of the kerf. 2. The step of determining the chipping state comprises:
Comparing the received light amount, which is the actually measured value, with the reference received light amount to determine whether the chipping state is abnormal.
The method for measuring chipping according to claim 1. 3. A chipping measuring device for measuring a chipping state of a kerf formed on a workpiece cut by a high-speed rotating blade, wherein at least chipping occurs in a predetermined region of a processing surface including the kerf. A light emitting device that irradiates slit-like light over a width wider than the width of the standard kerf, a light receiving device that receives light reflected from the processing surface, and determines a chipping state of the kerf according to the amount of light received by the light receiving device. And a chipping determination device. 4. A chipping judging device, comprising: a data conversion means for A / D converting the amount of light received by the light receiving device at a predetermined sampling frequency to generate received light amount data; and comparing the received light amount data with a reference received light amount. The chipping measurement device according to claim 3, further comprising: a determination unit configured to determine whether a chipping state is abnormal. 5. The chipping measurement device is provided in a dicing device, and the measured chipping state of the kerf can be fed back to cutting conditions of the dicing device or replacement of the blade. 5. The chipping measuring device according to any one of 4.