JP2006303367A - Cutting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting method, capable of omitting the process of having an operator detach an object to be worked from a chuck table and observe the back surface chipping state of the object to be worked, and automatically and fully performing pre-cutting. <P>SOLUTION: The cutting method is provided for preliminarily cutting and working the object to be worked by a cutting blade. The cutting method includes (1) a detection step of detecting a workload that the chuck table receives, by the cutting of the cutting blade to the object to be worked by a workload detection means 40, while cutting the cutting line of the object to be worked by the cutting blade; (2) a determining step of determining whether the detected workload has lowered from the state of being elevated to a prescribed threshold or higher to the prescribed threshold, or below by a determining means 50; and (3) an end step of making a preliminary cutting operation ended by a cutting device, when it is determined that the detected workload has lowered to the prescribed threshold or lower. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cutting method, and more particularly to a cutting method in which a workpiece is preliminarily cut with a cutting blade in order to stabilize the cutting ability of the cutting blade.

  As a cutting device for cutting a workpiece such as a semiconductor wafer, for example, a dicing device is known. This dicing apparatus is provided with a cutting means to which a cutting blade is detachably mounted, and the workpiece is picked up by a cutting blade that rotates at high speed while reciprocating the chuck table holding the work piece with respect to the cutting means. Cutting an object.

  The cutting blade has a structure in which abrasive grains such as diamond are fixed with a binder. These cutting blades are worn out with the passage of time of use, and the sharpness is reduced, so that the cutting blades are appropriately replaced. The new cutting blade immediately after being mounted on the cutting means has not yet fully exposed abrasive grains on the surface of the binder. For this reason, if the cutting is performed in this state, the cutting blade cannot exhibit sufficient cutting ability, so that large chipping occurs around the cut grooves on the front and back surfaces of the cut workpiece, and the workpiece is greatly damaged. It will cause damage.

  In order to prevent such problems, in order to stabilize the cutting ability of the cutting blade, the abrasive grains contained in the new cutting blade are sufficiently exposed on the surface of the binding material (so-called “scale”) prior to cutting. In addition, a preparatory cutting called pre-cut is performed. This precut is a trial cut using, for example, a test substrate (a dummy of a workpiece, hereinafter referred to as a “precut substrate”), and is performed on a precut substrate sucked and held on a chuck table (for example, Patent Document 1). reference).

  In this precut, the cutting line is cut by trial at a predetermined number of lines and a predetermined feed rate. The predetermined number of lines and feed speed are determined based on data obtained from past experience. In many cases, there is no problem if cutting is performed with the predetermined number of lines and feed speed. However, since the quality of the cutting blade is not necessarily uniform, the cutting ability of the cutting blade may not be sufficiently stable even if the cutting is performed with the predetermined number of lines and feed rate.

  Therefore, after pre-cutting the pre-cut substrate, the operator has observed the chipping state of the cutting groove formed in the pre-cut substrate with a microscope to check whether there is any problem in the chipping state.

Japanese Patent Laid-Open No. 11-176772 JP 2001-250797 A Japanese Patent Laid-Open No. 7-335592

  However, if the operator observes the chipping state of the cutting groove formed on the precut substrate, it is not only burdensome for the operator but also inefficient, and skill is also required to determine whether there is an abnormality. There was a problem. Therefore, the inventors of the present application examined a method for determining that the pre-cut was sufficiently performed without the operator observing.

  One possible method is to increase the number of lines for cutting the precut substrate. However, this method has a problem that productivity is reduced because pre-cutting takes time.

  Therefore, as an alternative method, a method of indirectly determining that pre-cutting has been sufficiently performed by indirectly grasping the chipping state formed in the cutting groove of the workpiece based on the cutting data is examined. did. As a method of indirectly grasping the chipping state, there is a method of monitoring the cutting resistance load acting on the cutting blade by the power consumption of the rotary motor, as described in Patent Document 2.

  However, when the workpiece is completely cut, the chipping generated by forming the cutting groove is often larger on the back surface side than on the front surface side of the workpiece. For this reason, there is no problem in the chipping state on the front surface side, but since the chipping state on the back surface side is bad, further pre-cutting is often required. Therefore, until now, the operator has been required to remove the workpiece from the chuck table, turn the workpiece over, and observe the back surface, which is particularly inefficient. However, there is a correlation between the chipping state on the front side and the cutting resistance load of the cutting blade, but no correlation can be found between the chipping state on the back side and the cutting resistance load of the cutting blade. Therefore, the method of estimating the chipping state based on the cutting resistance load of the cutting blade as in Patent Document 2 has a problem that it is difficult to estimate the backside chipping state.

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to perform a process in which the operator removes the workpiece from the chuck table and observes the back surface chipping state of the workpiece. It is an object of the present invention to provide a new and improved cutting method that can be omitted and automatically perform precutting sufficiently.

  In order to solve the above problem, the inventors of the present invention have a positive correlation between the back surface chipping state of the workpiece and the processing load received by the chuck table from the cutting blade, that is, as the processing load increases. We paid attention to the correlation that the backside chipping increased.

  Regarding this correlation, Patent Document 3 describes that there is a correlation between the processing load that the semiconductor wafer receives from the cutting blade during cutting and the back surface chipping. However, the invention described in Patent Document 3 keeps the backside chipping state good by controlling the driving of the cutting means according to the load applied to the semiconductor wafer when the semiconductor wafer to be actually manufactured is actually cut. There is no description or suggestion about applying this at the time of pre-cutting.

  As described above, the present inventors have intensively studied a method that can accurately determine that a new cutting blade has been sufficiently marked during pre-cutting. As a result, the processing load applied to the chuck table from the cutting blade and the back surface chipping have been studied. I came up with the idea of applying this correlation to pre-cutting.

  In other words, at the initial stage of precutting, when the abrasive grains contained in the cutting blade have not yet sufficiently protruded from the surface of the binder (when the alignment is not sufficient), the processing load acting on the chuck table is large, and accordingly The backside chipping is also great. After that, if pre-cutting is continued, the abrasive grains gradually protrude from the surface of the binder and the cutting performance of the cutting blade is improved, so that the processing load acting on the chuck table is gradually reduced and the back surface chipping is also reduced.

  Therefore, by measuring the machining load acting on the chuck table during pre-cutting, the back-surface chipping state at the time of pre-cutting can be suitably grasped based on the measured machining load, and the machining load is below a predetermined machining load. By pre-cutting up to, the chipping on the back surface is reduced to a level where there is no problem. Since the back surface chipping is larger than the front surface chipping, it can be determined that the pre-cut has been sufficiently performed if the back surface chipping is reduced to a level at which there is no problem. Thus, the inventors of the present invention have completed the following invention by utilizing the fact that the backside chipping state can be grasped indirectly and accurately by the processing load acting on the chuck table during pre-cutting.

  That is, in order to solve the above problems, according to one aspect of the present invention, the chuck table that holds the workpiece, the cutting blade that cuts the workpiece held by the chuck table, and the chuck table are acted on. A cutting ability of a cutting blade in a dicing apparatus comprising: a machining load detection unit that detects a machining load; and a determination unit that determines whether the machining load detected by the machining load detection unit is equal to or less than a predetermined threshold value. In order to stabilize the workpiece, a cutting method is provided in which a workpiece is preliminarily cut by a cutting blade. This cutting method includes (1) a detection step of detecting a processing load applied to the chuck table by cutting of the cutting blade with respect to the workpiece by the processing load detection means while cutting the cutting line of the workpiece with the cutting blade; (2) a determination step of determining whether or not the detected machining load is lowered from a state where the detected machining load has risen above a predetermined threshold to a predetermined threshold or less; (3) the detected machining load is predetermined An end step of ending the preparatory cutting operation by the cutting device when it is determined that the value has fallen below the threshold value.

  When the workpiece is preliminarily cut (pre-cut) with the cutting blade by the above-described cutting method, the back surface of the workpiece is measured based on the machining load by measuring the machining load on the chuck table. The chipping state can be suitably estimated. Therefore, it can be automatically and accurately determined by the cutting device that the precut has been sufficiently performed. Therefore, a skilled operator does not need to observe the back surface chipping state with a microscope, and it is not necessary to remove the workpiece from the chuck table in order to confirm the back surface chipping state. Furthermore, the cutting preparation operation can be automatically terminated when the machining load value becomes equal to or less than a predetermined threshold value. Therefore, the work efficiency of the precut work can be improved and the burden on the operator can be reduced.

  The workpiece may be a test board. Thereby, a preparatory cutting process (pre-cut) can be performed on a test substrate which is a dummy substrate on which a semiconductor circuit or the like is not formed. For this reason, the cost required for pre-cutting can be reduced without wasting the substrate on which the semiconductor circuit or the like is formed.

  As described above, according to the present invention, during preparatory cutting, an operator removes the workpiece from the chuck table and observes the back surface chipping state of the workpiece, thereby automatically precutting. Can be performed sufficiently.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
Hereinafter, a cutting method according to the first embodiment of the present invention, that is, a precut method that is a preparatory cutting operation for stabilizing the cutting ability of the cutting blade will be described.

  First, based on FIG. 1, the structure of the cutting device which performs the said cutting method, for example, a dicing apparatus, is demonstrated. FIG. 1 is an overall perspective view showing a dicing apparatus 10 according to the present embodiment.

  As shown in FIG. 1, the dicing apparatus 10 includes, for example, a cutting unit 20 that is a cutting unit that cuts a workpiece 12 such as a semiconductor wafer, and a chuck table 30 that is a holding unit that holds the workpiece 12. , A cutting unit moving mechanism (not shown) and a chuck table moving mechanism (not shown).

  The cutting unit 20 includes a cutting blade 22 attached to the tip of the spindle. The cutting blade 22 is an extremely thin cutting grindstone having a substantially ring shape, and is formed, for example, by fixing abrasive grains such as diamond and CBN with a binder (for example, metal bond, resin bond, electroformed bond, etc.). . The cutting unit 20 can cut the workpiece 12 to form an extremely thin kerf by cutting the cutting blade 22 into the workpiece 12 while rotating the cutting blade 22 at a high speed.

  The chuck table 30 is, for example, a disk-like table having a substantially flat upper surface, and includes a vacuum chuck (not shown) on the upper surface. For example, the workpiece 12 supported by the frame 14 via the wafer tape 13 is placed on the chuck table 30, and the workpiece 12 can be stably held by vacuum suction.

  The cutting unit moving mechanism moves the cutting unit 20 to the Y axis. The Y-axis direction is a horizontal direction orthogonal to the cutting direction (X-axis direction), and is, for example, the axial direction of a spindle disposed in the cutting unit 20. By such movement in the Y-axis direction, the cutting edge of the cutting blade can be aligned with the cutting position (cutting line) of the workpiece 12. The cutting unit moving mechanism also moves the cutting unit 20 in the Z-axis direction (vertical direction). Thereby, the cutting depth of the cutting blade 22 with respect to the workpiece 12 can be adjusted.

  During normal dicing, the chuck table moving mechanism moves the chuck table 30 holding the workpiece 12 back and forth in the cutting direction (X-axis direction) and feeds it to the workpiece 12 by the cutting blade 22. The cutting edge is operated with a linear trajectory.

  The dicing apparatus 10 having such a configuration moves the cutting line of the workpiece 12 by moving the cutting unit 20 and the chuck table 30 relative to each other in the X-axis direction while cutting the cutting blade rotating at a high speed into the workpiece 12. Can be cut. The workpiece 12 can be divided into a plurality of chips by dicing the workpiece 12 into a lattice shape by the dicing apparatus 10.

  Furthermore, as shown in FIG. 1, the dicing apparatus 10 is provided with a display device 16 such as a monitor. The display device 16 displays, for example, cutting conditions and cutting state at the time of cutting, a processing load on the chuck table 30 at the time of precut, a precut end notification, and the like.

  Next, the peripheral configuration of the chuck table 30 in the dicing apparatus 10 according to the present embodiment will be described with reference to FIG. FIG. 2 is a side view showing a peripheral configuration of the chuck table 30 in the dicing apparatus 10 according to the present embodiment.

  As shown in FIG. 2, the chuck table 30 includes a holding unit 32 that holds the workpiece 12 by suction, a support unit 34 that supports the holding unit 32, a rotation driving unit 36 that rotates the holding unit 32, and a support. And a moving base portion 38 that supports the portion 34 and the rotation driving portion 36.

  The holding unit 32 includes, for example, a disk-shaped vacuum chuck 322 made of a porous material, and a disk-shaped support table 324 that supports the vacuum chuck 322 from below. An exhaust path (not shown) communicating with an external vacuum pump is formed in the support table 324 via an exhaust pipe (not shown) arranged in the rotation drive unit 36. By operating the vacuum pump, a suction force is generated in the vacuum chuck 322 via the exhaust pipe and the exhaust path, and the workpiece 12 can be held by vacuum suction.

  The support part 34 includes, for example, an annular support member 342 that supports the holding part 32 via stress detectors 42A to 42C described later, and a plurality of support parts 342 that are fixed on the moving base part 38 (for example, support the annular support member 342). 4) struts 344. In the center of the annular support member 342, a circular through-hole 342a for inserting the rotation drive unit 36 is formed. For this reason, the annular support member 342 and the rotation drive unit 36 are not in contact with each other and do not interfere with each other.

  The rotation drive unit 36 has, for example, a cylindrical shape, and is fixed on the moving base unit 38. Inside the rotation drive unit 36, an exhaust pipe (not shown) for evacuation, a drive mechanism (not shown) such as a servo motor and an encoder for rotating the holding unit 32, and the like. Is arranged. The upper end of the rotation drive unit 36 is connected to the holding unit 32, but does not substantially support the holding unit 32. For this reason, the weight of the holding part 32 and the processing load applied to the holding part 32 act on the support part 34 via the stress detectors 42A to 42C.

  The moving base 38 is slidably disposed on a guide rail 39 extending in the X-axis direction. The moving base unit 38 is configured to be movable in the X-axis direction on the guide rail 39 by a drive mechanism (not shown) configured by, for example, a ball screw mechanism and a motor. By moving the movable base portion 38, the entire chuck table 30 can be reciprocated in the X-axis direction, which is the cutting direction, and the workpiece 12 can be cut along the cutting line.

  Furthermore, based on FIG. 2, the structure of the process load detection means concerning this embodiment is demonstrated. In the chuck table 30 according to the present embodiment, when the workpiece 12 is cut by the cutting blade 22, the machining load (hereinafter referred to as “processing to the chuck table 30”) that the chuck table 30 receives due to the cutting blade 22 being cut into the workpiece 12. A machining load detecting means for detecting “load” is provided.

  This processing load detection means includes, for example, a plurality of (for example, three) stress detectors 42A disposed at substantially equal intervals along the circumferential direction between the holding portion 32 and the support portion 34 of the chuck table 30. B and C are provided. The stress detectors 42A to 42C are composed of, for example, a Kistler dynamometer, but are not limited to such an example.

  The stress detectors 42 </ b> A to 42 </ b> C detect a downward stress in the vertical direction (Z-axis direction) that acts on the holding portion 32 of the chuck table 30 when the chuck table 30 receives a processing load from the cutting blade 22. . As described above, the holding portion 32 of the chuck table 30 is supported by the support portion 34 via the stress detectors 42A to 42C, and the support portion 34 does not move in the vertical direction. For this reason, when a machining load is applied to the holding portion 32 of the chuck table 30 during cutting, the stress detectors 42A to 42C are subjected to stress in the vertically lower direction received by the holding portion 32, and the stress detector 42A. ~ C can detect this stress value. In the present embodiment, the stress values detected by the stress detectors 42 </ b> A to 42 </ b> C are considered as processing load values for the chuck table 30.

  Further, a circuit configuration for determining that the pre-cut has been sufficiently performed in the dicing apparatus 10 according to the present embodiment will be described with reference to FIG. FIG. 3 is a block diagram showing a circuit configuration of the dicing apparatus 10 according to the present embodiment.

  As shown in FIG. 3, the dicing apparatus 10 according to the present embodiment includes a machining load detection unit 40 that detects a machining load on the chuck table 30, and whether the precut has been sufficiently performed based on the detected machining load. Determination means 50 for determining whether or not.

  In addition to the above-described three stress detectors 42A to 42C, the processing load detection means 40 is, for example, an average for calculating an average value of the processing load values (stress values) respectively detected by the stress detectors 42A to 42C. A value calculation unit 44, an A / D conversion unit 46 for analog / digital conversion of the machining load value input from the average value calculation unit 44, and a timing adjustment unit 48 for adjusting an interval for outputting a digital signal of the machining load value. Is further provided. The machining load detection unit 40 outputs the average value of the machining load values detected by the three stress detectors 42A to 42C to the determination unit 50.

  The determination unit 50 determines whether or not the machining load value detected by the machining load detection unit 40 is equal to or less than a predetermined threshold value set in advance. This predetermined threshold value is set to a suitable value based on the accumulated past cutting data, the chipping state observation result, and the like. The type of the cutting blade 22 used at the time of pre-cutting and the workpiece 12 are set. It is selectively determined according to the type.

  The machining load detection means 40 continuously detects a machining load value on the chuck table 30 while repeatedly cutting a plurality of cutting lines of the workpiece 12 during pre-cutting. The machining load value increases or decreases according to the progress of precut (see FIG. 6 described later).

  In other words, in the pre-cut, when the abrasive grains contained in the new cutting blade 22 after replacement do not sufficiently protrude on the surface of the binder, the cutting ability of the cutting blade 22 is low, so that the processing on the detected chuck table 30 is performed. The load is large. On the other hand, as the pre-cut progresses, the abrasive grains gradually protrude on the surface of the binder, and the cutting performance of the cutting blade 22 is improved, so that the processing load is gradually reduced. Furthermore, the processing load has a positive correlation with the size of the back surface chipping generated on the workpiece 12 as described above.

  The determination means 50 analyzes the transition of the machining load value with respect to the chuck table 30 at the time of such pre-cutting, and when the machining load value has increased from the above-mentioned predetermined threshold value to a value below the threshold value, it has already been determined. It is determined that the back surface chipping is within a size that does not cause a problem, and the pre-cut operation by the dicing apparatus 10 is automatically terminated.

  The average value calculation unit 44, the timing adjustment unit 46, and the determination unit 50 of the machining load detection unit 40 described above may be configured by a dedicated circuit such as an IC or the like, or may be included in the CPU of the dicing apparatus 10. It may be configured by an installed program.

  Next, a precut method using the dicing apparatus 10 having the above configuration will be described. The pre-cut is a cutting process that preliminarily cuts the workpiece 12 in order to stabilize the cutting ability of the cutting blade 22. In the following description, an example in which a precut substrate that is a test substrate is used as the workpiece 12 to be precut will be described, but the present invention is not limited to such an example.

  In the precut according to the present embodiment, the precut substrate is completely cut (full cut). This is in order to grasp the backside chipping state by performing pre-cutting in the same state as the substrate that is actually the product.

As a specific procedure of the pre-cut method, for example, a first pre-cut method and a second pre-cut method described below can be considered.

First, the first precut method will be described with reference to FIG. FIG. 4 is a flowchart showing the first precut method according to the present embodiment.

In the first precut method, the cutting load of the precut substrate is sequentially cut by the cutting blade 22 while detecting the processing load acting on the chuck table 30 by the processing load detection means 40, and the determination means 50 ends the precut. This is a method of ending the precut operation when it is determined (first precut method).

Specifically, as shown in FIG. 4, first, in step S10, the cutting load of the precut substrate is cut by the new cutting blade 22 after replacement, and the machining load detecting means 40 acts on the chuck table 30. The machining load to be detected is detected (step S10; detection step).

Next, in step S12, the determination means 50 determines whether or not the detected machining load has decreased below the predetermined threshold from the state where the detected processing load has increased above the predetermined threshold (step S12; determination). Step). As a result of this determination, if it is determined that the detected machining load has not decreased below a predetermined threshold value, the process returns to step S10, and the machining load is detected again while cutting the cutting line of the precut substrate. Is done. As a result, the cutting line of the pre-cut substrate is repeatedly cut and the cutting blade 22 is calibrated until the detected processing load falls below a predetermined threshold.

As a result, in this step S12, when it is determined that the detected processing load has decreased below a predetermined threshold value, the cutting blade 22 is suitably aligned, and therefore the back surface chipping that occurs on the precut substrate is prevented. It can be judged that the size has been reduced to a satisfactory level and the pre-cut has been performed sufficiently. Therefore, it progresses to step S14 and the pre-cut operation | movement by the dicing apparatus 10 is complete | finished (step S14; completion | finish step). This end operation may be automatically performed by the control device of the dicing device 10 based on an instruction from the determination unit 50, or the user who viewed the pre-cut end notification displayed on the display device 16 ends. It may be done manually by pressing a button.

The reason why the determination criterion in step S12 is “the machining load has dropped from a state where it has risen above a predetermined threshold value” is as follows. Generally, at the initial stage of pre-cutting, the cutting feed speed of the chuck table 30 is set low, so that the cutting resistance acting on the cutting blade 22 is small (for example, 10 mm / sec), and therefore the processing load on the chuck table 30 is also high. It becomes smaller and less than the predetermined threshold value. Thereafter, when the precut proceeds to some extent and a high cutting feed rate (for example, 70 mm / sec) used in normal cutting is applied, the processing load on the chuck table 30 inevitably rises above a predetermined threshold. To do. Therefore, in order to use the processing load after the high cutting feed speed is applied as the target data for the pre-cut end judgment criterion, the processing is detected after “the state where the pre-cut threshold is raised above a predetermined threshold”. It was decided to determine whether or not the load fell below the threshold.

The first precut method has been described above. In this method, every time a predetermined number of cutting lines (one or a plurality of cutting lines) are cut, the determination means 50 performs a pre-cut end determination process to determine whether or not to continue the pre-cut operation. Therefore, immediately after the machining load drops below the predetermined threshold value, the precut operation can be completed at an early stage, and the efficiency of the precut work can be improved.

Next, the second precut method will be described with reference to FIG. FIG. 5 is a flowchart showing a second precut method according to the present embodiment.

In the second precut method, a plurality of cutting lines of the precut substrate are set by a cutting blade 22 in a predetermined predetermined precut procedure while the processing load acting on the chuck table 30 is detected by the processing load detecting means 40. After cutting all in accordance with the (preparation cutting procedure), the determination by the determination means 50 is executed. When it is determined that the precut has been completed, the precut operation is terminated. This is a method of repeatedly cutting a plurality of cutting lines according to the same or different pre-cutting procedure as described above until it is determined that the pre-cut is finished.

Specifically, as shown in FIG. 5, first, in steps S20 and S22, the processing load detection is performed while cutting a plurality of cutting lines of the precut substrate by the cutting blade 22 according to a predetermined precutting procedure set in advance. The machining load acting on the chuck table 30 is continuously detected by the means 40 (steps S20 and S22; detection step).

Here, the “predetermined predetermined precut procedure” refers to, for example, cutting while appropriately changing the cutting conditions (cutting feed speed, cutting depth, etc.) and the number of cutting lines cut under each cutting condition. This is a standard cutting procedure for cutting as many cutting lines as the blade 22 can be sufficiently marked. This pre-cut procedure is determined in advance based on past experience (see FIG. 6).

More specifically, first, in step S20, the cutting load of the pre-cut substrate is cut by the processing load detecting means 40 with respect to the chuck table 30 while the cutting line of the pre-cut substrate is cut by the new cutting blade 22 after replacement according to the predetermined pre-cutting procedure. The machining load acting is detected (step S20).

Next, in step S22, the determination means 50 determines whether or not all the predetermined precut procedures have been completed (step S22). If it is determined that the predetermined precut procedure has not been completed, the process returns to step S20. Cut the next cutting line according to the pre-cut procedure. When such an operation is repeated and it is finally determined that all the predetermined precut procedures have been completed, the process proceeds to the next step S24.

Next, in step S24, it is determined whether or not the machining load detected at the end of the preparatory cutting step S20 has fallen below a predetermined threshold (step S24). Here, “at the end of the preparatory cutting step S22” means when cutting one or more cutting lines that are cut immediately before the end of the predetermined pre-cutting procedure. It doesn't mean.

As the pre-cut procedure as described above proceeds, the cutting blade 22 is indexed and the cutting ability is increased, so that the machining load on the chuck table 30 gradually decreases in the second half of the pre-cut procedure. In determination step S24, it is determined whether or not the machining load thus reduced has decreased to a predetermined threshold value or less.

As a result of this determination, if it is determined that the machining load detected at the end of the precut procedure has not decreased below a predetermined threshold value, the process returns to step S20, and a plurality of cutting lines of the precut substrate are again formed. The machining load is detected while cutting with a predetermined pre-cut procedure. As a result, the pre-cutting procedure is repeated a plurality of times until the detected machining load is equal to or less than a predetermined threshold value, and the cutting blade 22 is scaled. The pre-cut procedure after the second time may be the same as the pre-cut procedure executed first or a pre-cut procedure different from the pre-cut procedure executed first (for example, the pre-cut procedure executed first). Rather than a pre-cutting procedure in which the number of cutting lines is reduced).

  As a result, when it is determined that the detected processing load has decreased below a predetermined threshold value, the cutting blade 22 is suitably aligned so that the back surface chipping generated on the pre-cut substrate is reduced to a level with no problem. Therefore, it can be judged that the pre-cut was sufficiently performed. Therefore, it progresses to step S26 and the pre-cut operation | movement by the dicing apparatus 10 is complete | finished (step S26; completion | finish step). This termination operation may be performed automatically as described above or manually.

  The second precut method has been described above. In this method, at the end of a predetermined precut procedure, the determination means 50 performs a precut end determination process to determine whether or not to continue the precut operation. Therefore, despite the execution of the pre-cutting procedure, it is possible to automatically determine that the cutting blade 22 is not sufficiently aligned and that a relatively large back surface chipping has occurred. For this reason, it is possible to instruct the execution of a further pre-cutting procedure to perform the pre-cutting procedure until the cutting blade 22 is suitably marked, and to reduce the burden on the operator.

  Further, in addition to the above configuration, for example, as in Patent Document 2, a configuration may be added in which a cutting resistance load applied to the cutting blade 22 is detected by the power consumption of the spindle motor with respect to the dicing apparatus 10. In this case, the surface chipping state of the precut substrate may be estimated based on the cutting resistance load of the cutting blade 22, and the precut operation may be terminated when the cutting resistance drops below a certain threshold value. As described above, based on both the cutting force of the cutting blade 22 and the processing load on the chuck table 30, both the front surface chipping state and the back surface chipping state are grasped, and it is determined that the precut has been sufficiently performed. You can also However, in the pre-cut, if there is no problem in the chipping state on the back surface side, the chipping state on the front surface side often has no problem, so this configuration is not essential, but there is an effect that the determination accuracy can be further improved.

  Next, the result of conducting an experiment of precutting a precut substrate in order to verify that there is a positive correlation between the processing load on the chuck table 30 and the back surface chipping will be described.

  First, the experimental conditions are explained. At the time of pre-cutting, a pre-cut substrate having a thickness of 400 μm was cut using a cutting blade 22 having a grain size of # 2000 with diamond abrasive grains fixed by electroforming bond and a spindle rotation speed of 30000 RPM.

  Further, in the precut according to this experiment, after the feed rate of the cutting blade 22 is gradually increased from 10 mm / sec and increased to 70 mm / sec, the feed rate is kept constant at 70 mm / sec. A pre-cut procedure of increasing the number of lines was adopted.

  The processing load on the chuck table 30 and the backside chipping size when precutting according to such a procedure were measured at each stage during precutting. The experimental results are shown in FIG.

  FIG. 6 is a graph showing the relationship between the size [μm] of the back surface chipping measured in the precut experiment and the processing load [gF (weight g)] on the chuck table 30. In the horizontal axis of the graph of FIG. 6, for example, “10-10” represents a stage after 10 lines are pre-cut at a feed rate of 10 mm / sec, and “20-10” is 10 at a feed rate of 20 mm / sec. “70-20” represents a stage after pre-cutting 20 lines at a feed rate of 70 mm / sec, and “70-20” represents the stage after the line is pre-cut.

  According to the experimental results shown in FIG. 6, the back surface chipping size and the processing load on the chuck table 30 increase and decrease with the same tendency as the precut progresses, and there is a positive correlation between the two. .

  Further, according to the experimental results, it can be seen that the processing load and the back surface chipping size are both stable after the “70-120” stage where the processing load is 13 gF, and the back surface chipping size is approximately 100 μm or less. It has become. If the back surface chipping size is 100 μm or less, it can be determined that the pre-cut may be completed, and therefore the processing load threshold for the chuck table 30 can be set to 13 gF, for example. With this setting, when the detected machining load is reduced to 13 gF or less, it is determined that the pre-cut is finished.

  However, since the feed speed is gradually increased during precut, the detected machining load is 13 gF or less at the initial stage of precut. For this reason, it is necessary to determine whether or not the detected machining load once increases until it exceeds 13 gF, which is the threshold, and then decreases to 13 gF or less.

  The precut method according to the present embodiment has been described in detail above. According to the precut method according to the present embodiment, the precut substrate is preliminarily cut (precut) by the cutting blade 22, and the processing load on the chuck table 30 is detected, so that the back surface of the precut substrate is based on the processing load. The chipping state can be suitably estimated. Therefore, it can be automatically and accurately determined by the dicing apparatus 10 that the pre-cut has been sufficiently performed. Therefore, an operator having skill does not need to observe the back surface chipping state with a microscope, and it is not necessary to remove the workpiece 12 from the chuck table 30 in order to confirm the back surface chipping state. Furthermore, the cutting preparation operation can be automatically terminated when the machining load value becomes equal to or less than a predetermined threshold value. Therefore, the work efficiency of the precut work can be improved and the burden on the operator can be reduced.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above embodiment, the dicing apparatus 10 has been described as an example of the cutting apparatus, but the present invention is not limited to such an example. For example, as long as it is a device that cuts the workpiece 12 using the cutting blade 22 that rotates at high speed, for example, various cutting devices that perform cutting processing other than dicing processing may be used.

  In the above-described embodiment, an example in which a precut substrate that is a test substrate is used as the workpiece 12 to be precut has been described. However, the present invention is not limited to such an example, and an actual product in which a circuit or the like is formed is used. Precutting may be performed using a workpiece to be processed (such as a semiconductor wafer).

  In the above embodiment, for example, three Kistler dynamometers, which are the stress detectors 42, are used as the processing load detection means, but the present invention is not limited to such an example. For example, a stress detector other than the Kistler dynamometer may be used, and the installation location and the number of installations can be appropriately changed in design. Further, if the apparatus can detect a physical property value corresponding to the machining load on the chuck table 30, for example, a strain gauge or a displacement detector is installed at an arbitrary position of the chuck table 30, or the workpiece 12 and the chuck A physical property value corresponding to a machining load on the chuck table 30 may be detected by arranging a piezoelectric element or the like between the table 30 and the like.

  In the above embodiment, when cutting the workpiece 12, the cutting unit 20 provided with the cutting blade 22 is fixed, and the chuck table 30 holding the workpiece 12 is moved in the X-axis direction. The present invention is not limited to such an example. For example, only the cutting unit 20 may be moved in the X-axis direction, or both the cutting unit 20 and the chuck table 30 may be moved simultaneously.

  The present invention can be applied to a cutting method in which a workpiece is preliminarily cut by a cutting blade in order to stabilize the cutting ability of the cutting blade.

1 is an overall perspective view showing a dicing apparatus according to a first embodiment of the present invention. It is a side view which shows the periphery structure of the chuck table in the dicing apparatus concerning the embodiment. It is a block diagram which shows the circuit structure of the dicing apparatus concerning the embodiment. It is a flowchart which shows the 1st precut method concerning the embodiment. It is a flowchart which shows the 2nd precut method concerning the embodiment. It is a graph showing the relationship between the size of the back surface chipping measured in the precut experiment according to the embodiment and the processing load on the chuck table.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Dicing apparatus 12: Workpiece 16: Display apparatus 20: Cutting unit 22: Cutting blade 30: Chuck table 32: Holding part 34: Support part 36: Moving base part 40: Work load detection means 42A-C: Stress Detector 44: Average value calculation unit 46: A / D conversion unit 48: Timing adjustment unit 50: Determination means

Claims (2)

A chuck table for holding a workpiece, a cutting blade for cutting the workpiece held by the chuck table, a machining load detection means for detecting a machining load acting on the chuck table, and the machining load detection means And a determination means for determining whether or not the processing load detected by the step is equal to or less than a predetermined threshold value, in order to stabilize the cutting ability of the cutting blade, the workpiece by the cutting blade A cutting method for preparatory cutting:
A detection step of detecting a processing load applied to the chuck table by the cutting of the cutting blade with respect to the workpiece by the processing load detection means while cutting the cutting line of the workpiece with the cutting blade;
A determination step of determining by the determination means whether or not the detected machining load has decreased below the predetermined threshold from a state where the detected load has increased above the predetermined threshold;
An ending step of ending the preparatory cutting operation by the cutting device when it is determined that the detected processing load has dropped below the predetermined threshold;
A cutting method characterized by comprising:   The cutting method according to claim 1, wherein the workpiece is a test substrate.

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