JP2019201061A - Processing method of workpiece - Google Patents

Abstract

To provide a processing method of workpiece capable of restraining occurrence of processing failure, when processing a tabular workpiece by irradiating with a laser beam.SOLUTION: A processing method of workpiece for processing a tabular workpiece including N (N is a natural number of 3 or more) scheduled lines set at regular intervals comprises a first processing step of forming a processing mark on the workpiece by irradiating a first scheduled line existing at a first position where the distance from the scheduled line located at the outermost side of the workpiece is represented by 2×D (D is the distance of two adjoining first scheduled line, n is the maximum natural number satisfying 2<N) with a laser beam, and a (k+1)th processing step of forming a processing mark on the workpiece by irradiating the scheduled line, selected from the first scheduled line existing at a (k+1)th position where the distance from the k-th position (k is a natural number of less than n) is represented by 2×D×m (m is a natural number), with the laser beam.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a workpiece processing method for processing a plate-like workpiece along a predetermined division line.

  Device chips incorporated into various electronic devices are divided into a plurality of areas on the surface of a wafer, which is a base material, by dividing lines called streets, and devices such as integrated circuits are formed in each area. It is obtained by dividing along the planned dividing line. In order to divide the wafer, for example, a cutting device that rotates an annular cutting blade and cuts into a target is used.

  In wafer cutting using this cutting apparatus, the wafer is mechanically cut by a rotating cutting blade. Therefore, for example, if there is a bias in the load acting on the wafer from one side surface (front surface) and the other side surface (back surface) of the cutting blade, processing defects such as chipping and cracking are likely to occur in the wafer. . In addition, when such load imbalance increases, the cutting blade may be damaged.

  In view of this, a method has been proposed in which the order in which the cutting blades are cut into the wafer is devised to reduce the bias of the load acting between the cutting blade and the wafer (see, for example, Patent Document 1). In this method, the deviation of the load acting between the cutting blade and the wafer is reduced by cutting the cutting blade into the planned dividing line of the wafer in such an order that the areas of the two pieces generated by the division are approximately equal. doing.

  There is also known a method of dividing a wafer using a laser processing apparatus capable of irradiating a laser beam having a wavelength exhibiting absorption with respect to the wafer instead of the above-described cutting apparatus (see, for example, Patent Document 2). In this method using a laser processing apparatus, a processing mark (groove) that divides a wafer is formed by irradiating a pulsed laser beam along a planned division line of the wafer.

JP-A-4-245663 JP-A-10-305420

  However, even when a wafer is processed by the above-described method using a laser processing apparatus, processing defects such as chipping and cracking may occur in the wafer.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a workpiece that can suppress the occurrence of processing defects when processing a plate-like workpiece by irradiating a laser beam. It is to provide a processing method.

According to one aspect of the present invention, plate-like workpieces divided into a plurality of regions by N (N is a natural number of 3 or more) division planned lines set at equal intervals are used as the division division lines. A method of processing a workpiece to be processed by irradiating a laser beam along a distance of 2 ⁿ × D (D is two adjacent lines) from the divisional line located on the outermost side of the workpiece. The laser beam is irradiated to the division line existing at the first position represented by the distance of the division line, and n is a maximum natural number satisfying 2 ⁿ <N), and a work trace is formed on the workpiece. A first machining step to be formed, and after the first machining step, a distance from the k-th position (k is a natural number equal to or less than ⁿ ) is represented by 2 ^n−k × D × m (m is a natural number). The scheduled division line selected from the planned division lines existing at the k + 1 position Irradiating the laser beam to form a machining mark on the workpiece, and performing the k + 1 machining step in order for k from 1 to n, and in the k + 1 machining step, There is provided a processing method of a workpiece in which the division line not irradiated with the laser beam is selected in all the i-th processing steps in which i is a natural number equal to or less than k.

  In one embodiment of the present invention, the workpiece may be a GaAs wafer.

  In the processing method of the workpiece according to one aspect of the present invention, after forming a processing mark on the workpiece and dividing the region into a region having a certain size, the processing method is positioned between two already formed processing marks. Since a new machining trace is formed by irradiating the first division line with a laser beam, the area sandwiched between the two machining traces that have already been formed has the same volume as the newly formed machining trace. It will be divided into two small areas.

  For this reason, even if the existing processing traces hinder the conduction of heat generated during laser beam irradiation, heat can be conducted in the same way in the two small regions. That is, a temperature difference due to heat during processing hardly occurs between one of the two small regions and the other, so that it is possible to suppress the occurrence of processing failure due to uneven heat conduction. Thus, according to one embodiment of the present invention, there is provided a processing method for a workpiece that can suppress the occurrence of processing defects when processing a plate-shaped workpiece by irradiating a laser beam.

It is a perspective view which shows the structural examples, such as to-be-processed object. It is a perspective view which shows a mode that a to-be-processed object is processed. It is a top view which shows the to-be-processed object processed along the division | segmentation scheduled line which exists in a 1st position. It is a top view which shows the to-be-processed object processed along the division | segmentation scheduled line which exists in a 2nd position. It is a top view which shows the to-be-processed object processed along the division | segmentation scheduled line which exists in a 3rd position. It is a top view which shows the to-be-processed object processed along the division | segmentation scheduled line which exists in a 4th position.

  When processing marks such as grooves are formed on a plate-shaped workpiece by irradiating a laser beam, for example, if the workpiece is processed sequentially from the end, processing defects such as chipping and cracking will occur in the workpiece. It becomes easy. This phenomenon is caused by a large temperature due to the heat generated during laser beam irradiation between two regions when one of the two regions divided by the processing mark formed by laser beam irradiation is sufficiently small. It is inferred that the difference is caused.

  That is, it is considered that this problem can be solved if the heat generated during laser beam irradiation can be conducted in the same manner in two regions separated by the processing mark. Therefore, in the present invention, after forming a plurality of machining marks on a workpiece and dividing the area into a region of a certain size, a laser beam is applied to a planned division line positioned between two already formed machining marks. Irradiate to form new processing marks.

  As a result, the region sandwiched between the two existing processing marks is divided into two small regions having the same volume by the newly formed processing marks. Even if heat conduction generated during irradiation with the laser beam is hindered, heat can be conducted in the same manner in the two small regions.

  Embodiments according to one aspect of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view illustrating a configuration example of a plate-like workpiece 11 processed by the workpiece processing method according to the present embodiment. As shown in FIG. 1, the workpiece 11 is a disk-shaped GaAs wafer made of, for example, GaAs (gallium arsenide).

  The surface 11a side of the workpiece 11 is parallel to a plurality of straight first division planned lines 13a parallel to the first direction (A direction) and a second direction (B direction) intersecting the first direction. It is divided into a plurality of small regions by a plurality of straight second division planned lines 13b. That is, the first division planned line 13a and the second division planned line 13b intersect each other.

  A device 15 such as an IC (Integrated Circuit) is provided in each small area. Although FIG. 1 shows the workpiece 11 in which the first direction and the second direction are substantially perpendicular, it is sufficient that the first direction and the second direction intersect at least. That is, the first direction and the second direction need not be parallel.

  Moreover, there is no restriction | limiting in the material of the workpiece 11, a shape, a structure, a magnitude | size, etc. For example, the substrate 11 made of a material such as another semiconductor, ceramics, resin, or metal can be used as the workpiece 11. Similarly, the type, quantity, shape, structure, size, arrangement, etc. of the device 15 are not limited. The device 15 may not be formed on the workpiece 11.

  A dicing tape 17 having a diameter larger than that of the workpiece 11 is attached to the back surface 11b side of the workpiece 11. The outer peripheral portion of the tape 17 is attached to an annular frame 19 having a generally circular opening 19a. That is, the workpiece 11 is supported by the frame 19 via the tape 17.

  In addition, in this embodiment, in order to process the to-be-processed object 11 from the surface 11a side, the tape 17 is affixed on the back surface 11b side. However, when processing the to-be-processed object 11 from the back surface 11b side, What is necessary is just to stick the tape 17 to the 11a side. Further, when a jig table that directly holds the workpiece 11 is used, the tape 17 may not be attached to the workpiece 11.

  FIG. 2 is a perspective view showing how the workpiece 11 is processed. In the workpiece processing method according to the present embodiment, for example, the workpiece 11 is processed using the laser processing apparatus 2 shown in FIG. The laser processing apparatus 2 includes a chuck table 4 for holding a workpiece 11.

  For example, a holding plate (not shown) made of a porous material is exposed at a part of the upper surface of the chuck table 4. The upper surface of the holding plate is formed substantially parallel to the X-axis direction and the Y-axis direction, and is connected to a suction source (not shown) via a suction path (not shown) provided inside the chuck table 4. ing.

  A plurality of clamps (not shown) for fixing the annular frame 19 are provided around the chuck table 4. Further, a moving mechanism (not shown) and a rotating mechanism (not shown) are connected to the lower portion of the chuck table 4. The chuck table 4 is moved in the X-axis direction (machining feed direction) and the Y-axis direction (index feed direction) by this moving mechanism, and is rotated around a rotation axis substantially parallel to the Z-axis direction (vertical direction) by the rotating mechanism. To do.

  A laser processing unit 6 is disposed above the chuck table 4. The laser processing unit 6 irradiates and focuses a laser beam 21 pulsed by a laser oscillator (not shown) at a predetermined position. The laser oscillator used in the present embodiment is configured to be able to pulse-oscillate a laser beam 21 having a wavelength that is absorptive with respect to the workpiece 11, and is suitable for ablation processing of the workpiece 11.

  A camera (imaging unit) 8 for imaging the workpiece 11 and the like is disposed on the side of the laser processing unit 6. Based on the image acquired by the camera 8, for example, the angle formed between the first division planned line 13a (or the second division planned line 13b) of the workpiece 11 and the X-axis direction is adjusted.

  In the workpiece processing method according to the present embodiment, first, the workpiece 11 is held on the chuck table 4 of the laser processing apparatus 2 (holding step). Specifically, the negative pressure of the suction source is applied after the tape 17 attached to the back surface 11b side of the workpiece 11 is brought into contact with the upper surface of the chuck table 4 (holding plate). At the same time, the frame 19 is fixed with a clamp. Thereby, the to-be-processed object 11 is hold | maintained in the state which the surface 11a side exposed upwards.

  After the workpiece 11 is held on the chuck table 4, the workpiece 11 is processed by irradiating the laser beam 21 (processing step). In this embodiment, the procedure for processing the workpiece 11 only along the first division line 13a will be described. However, the workpiece 11 is further processed along the second division line 13b in the same procedure. You may do it. Of course, the workpiece 11 can be processed only along the second division line 13b.

Specifically, first, N is the total number of first division planned lines 13a set on the workpiece 11, D is the distance between two adjacent first division planned lines 13a, and n is 2 ⁿ <N. As the maximum natural number satisfying the above, the laser beam is applied to the first planned dividing line 13a existing at the first position where the distance from the first planned dividing line 13a located on the outermost side of the workpiece 11 is represented by 2 ⁿ × D. 21 is processed to process the workpiece 11 (first processing step).

In addition, since ⁿ satisfying 2 ⁿ <N is a natural number, the total number of the first division planned lines 13a to be processed must be three or more. The plurality of first division planned lines 13a need to be set at approximately equal intervals. That is, N (N is a natural number of 3 or more) first division planned lines 13a are set on the workpiece 11 at approximately equal intervals.

  On the other hand, there is no limitation on the number and arrangement of the second scheduled division lines 13b. Of course, when the workpiece 11 is processed along the second scheduled division line 13b in the same procedure as in the present embodiment, the second scheduled division line 13b is set to satisfy the same conditions as the first scheduled division line 13a. Is set.

FIG. 3 is a plan view showing the workpiece 11 processed along the division line 13a existing at the first position L1. Below, the total number of the 1st division | segmentation scheduled lines 13a set to the to-be-processed object 11 is demonstrated as 11 lines (namely, N = 11). In this case, the maximum natural number n satisfying 2 ⁿ <N is 3. Therefore, the distance from the first division planned line 13a (reference position L0) located on the outermost side of the workpiece 11 to the first position L1 is 8 × D as shown in FIG.

  When irradiating the laser beam 21 along the first division planned line 13a existing at the first position L1, first, the chuck table 4 is moved and the first division planned line 13a existing at the first position L1 is moved. The laser processing unit 6 is positioned above the extension line. In addition, when the X-axis direction of the laser processing apparatus 2 and the 1st division | segmentation scheduled line 13a of the to-be-processed object 11 are not parallel, the chuck table 4 is rotated and the direction of the 1st division | segmentation scheduled line 13a is made. Adjust it.

  Thereafter, the chuck table 4 is moved in the X-axis direction while irradiating the workpiece 11 with a laser beam 21 having an absorptive wavelength from the laser processing unit 6. As a result, the first machining trace (groove) 11c can be formed by irradiating the first division planned line 13a existing at the first position L1 with the laser beam 21. The depth of the first machining mark 11c is not limited. For example, it is possible to form the first processing mark 11c having a depth for dividing (cutting) the workpiece 11.

After the formation of the first processing mark 11c, the distance from the first position L1 to the first division planned line 13a existing at the second position L2 represented by 2 ⁿ⁻¹ × D × m (m is a natural number) The workpiece 11 is processed by irradiating a laser beam (second processing step).

FIG. 4 is a plan view showing the workpiece 11 processed along the division line 13a existing at the second position L2. As described above, the maximum natural number n satisfying 2 ⁿ <N is 3. Therefore, as shown in FIG. 4, the distance from the first position L1 to the second position L2 is 4 × D × m. In FIG. 4, only a representative second position L2 is shown.

  When irradiating the laser beam 21 along the first division planned line 13a existing at the second position L2, first, the chuck table 4 is moved to extend any one of the target first division planned lines 13a. The laser processing unit 6 is positioned above the line. Then, the chuck table 4 is moved in the X-axis direction while irradiating the workpiece 11 with a laser beam 21 having an absorptive wavelength from the laser processing unit 6.

  As a result, it is possible to form the second processing trace (groove) 11d by irradiating any one of the target first division planned lines 13a with the laser beam 21. The depth of the second machining mark 11d is not limited. Thereafter, the same procedure is repeated to irradiate all target first division planned lines 13a with the laser beam 21 to form the second processing trace 11d.

  In FIG. 4, the second position L <b> 2 outside the workpiece 11 is also shown, but naturally, the second position L <b> 2 may not be irradiated with the laser beam 21. On the other hand, the distance from the first position L1 is represented by 4 × D × 2, and the first division planned line 13a existing at the second position L2 overlapping the reference position L0 is irradiated with the laser beam 21.

After forming the second machining mark 11d, the distance from the second position L2 of the first division planned line 13a existing at the third position L3 represented by 2 ⁿ⁻² × D × m (m is a natural number) Among them, the first division planned line 13a in which neither the first machining trace 11c nor the second machining trace 11d is formed (that is, the first division schedule where the laser beam is not irradiated in the first machining step and the second machining step). The workpiece 11 is processed by irradiating the line 13a) with a laser beam (third processing step).

FIG. 5 is a plan view showing the workpiece 11 processed along the division line 13a existing at the third position L3. As described above, the maximum natural number n satisfying 2 ⁿ <N is 3. Therefore, as shown in FIG. 5, the distance from the second position L2 to the third position L3 is 2 × D × m. In FIG. 5, only a representative third position L3 is shown.

  When irradiating the laser beam 21 along the first division planned line 13a in which neither the first machining trace 11c nor the second machining trace 11d is formed among the first division planned lines 13a existing at the third position L3. First, the chuck table 4 is moved, and the laser processing unit 6 is positioned above the extension line of any one of the first planned division lines 13a. Then, the chuck table 4 is moved in the X-axis direction while irradiating the workpiece 11 with a laser beam 21 having an absorptive wavelength from the laser processing unit 6.

  Thereby, the 3rd process trace (groove | channel) 11e can be formed by irradiating the laser beam 21 to any 1st division | segmentation planned line 13a used as object. The depth of the third machining mark 11e is not limited. Thereafter, the same procedure is repeated to irradiate all target first division planned lines 13a with the laser beam 21 to form the third processing trace 11e.

After forming the third processing mark 11e, the distance from the third position L3 of the first division planned line 13a existing at the fourth position L4 represented by 2 ⁿ⁻³ × D × m (m is a natural number) Among them, the first division line 13a in which none of the first machining trace 11c, the second machining trace 11d, and the third machining trace 11e is formed (that is, the first machining step, the second machining step, and the third machining step). Then, the workpiece 11 is processed by irradiating the first division planned line 13a) not irradiated with the laser beam with a laser beam (fourth processing step).

FIG. 6 is a plan view showing the workpiece 11 processed along the division line 13a existing at the fourth position L4. As described above, the maximum natural number n satisfying 2 ⁿ <N is 3. Therefore, as shown in FIG. 6, the distance from the third position L3 to the fourth position L4 is 1 × D × m. In FIG. 6, only a representative fourth position L4 is shown.

  Of the first planned dividing line 13a existing at the fourth position L4, the laser is along the first divided planned line 13a in which none of the first processed mark 11c, the second processed mark 11d, and the third processed mark 11e is formed. When irradiating the beam 21, first, the chuck table 4 is moved, and the laser processing unit 6 is positioned above the extension line of any one of the first planned division lines 13 a. Then, the chuck table 4 is moved in the X-axis direction while irradiating the workpiece 11 with a laser beam 21 having an absorptive wavelength from the laser processing unit 6.

  As a result, the fourth processing trace (groove) 11f can be formed by irradiating one of the target first division lines 13a with the laser beam 21. The depth of the fourth machining mark 11f is not limited. Thereafter, the same procedure is repeated to irradiate all target first division planned lines 13a with the laser beam 21 to form the fourth machining trace 11f. As a result, the workpiece 11 has been processed along all the first division planned lines 13a.

  As described above, in the processing method of the workpiece according to the present embodiment, the processing marks (the first processing marks 11c and the second processing marks 11d) are formed on the workpiece 11 and divided into regions of a certain size. After that, the laser beam 21 is irradiated to the first division planned line 13a located in the middle of the two already formed processing marks to form new processing marks (third processing marks 11e, fourth processing marks 11f). Therefore, a region sandwiched between two already formed processing marks is divided into two small regions having the same volume by a newly formed groove.

  For this reason, even if the existing processing traces prevent the heat conduction that occurs when the laser beam 21 is irradiated, the heat can be conducted in the same manner in the two small regions. That is, a temperature difference due to heat during processing hardly occurs between one of the two small regions and the other, so that it is possible to suppress the occurrence of processing failure due to uneven heat conduction.

  In addition, this invention is not restrict | limited to description of the said embodiment, A various change can be implemented. For example, in the above embodiment, the case where the total number of the first division planned lines is 11 is mainly described. However, the total number of the first division planned lines is arbitrary N (N is a natural number of 3 or more). ), The workpiece 11 can be processed in the following procedure.

First, the distance from the first division planned line located on the outermost side of the workpiece is 2 ⁿ × D (D is the distance between two adjacent first division planned lines, and n is the maximum satisfying 2 ⁿ <N. The first division planned line existing at the first position represented by (natural number) is irradiated with a laser beam to form a processing mark (groove) on the workpiece (first processing step). In addition, this 1st process step is the same as that of the said embodiment.

After the first machining step, the first division exists at the (k + 1) th position where the distance from the kth position (k is a natural number equal to or less than ⁿ ) is represented by 2 ^n−k × D × m (m is a natural number). A laser beam is irradiated to the first division planned line selected from the planned lines to form a processing mark on the workpiece (k + 1 processing step).

  This k + 1th processing step is sequentially performed for k from 1 to n. In the (k + 1) -th processing step, a division planned line that is not irradiated with a laser beam in all i-th processing steps in which i is a natural number equal to or less than k is selected. Specifically, for example, in the fifth processing step, the division line 13a that is not irradiated with the laser beam in the first processing step, the second processing step, the third processing step, and the fourth processing step is selected. become.

  Further, in the above embodiment, the workpiece 11 is ablated by irradiating the workpiece 11 with a laser beam 21 having an absorptive wavelength. There is no particular limitation on the wavelength. For example, even when a laser beam having a wavelength that is transmissive to the workpiece 11 is used, the workpiece 11 is ablated by sufficiently concentrating the laser beam to cause multiphoton absorption. be able to.

  Moreover, although the said embodiment demonstrated the procedure which processes the to-be-processed object 11 only along the 1st division | segmentation scheduled line 13a, the 1st division | segmentation scheduled line 13a and the 2nd division | segmentation scheduled line 13b are processed alternately. Also good. In this case, for example, after the first processing step for processing the first division planned line 13a, the first processing step for processing the second division planned line 13b is performed, and then the first division planned line is performed. The workpiece 11 can be processed by the procedure of performing the second processing step for processing 13a.

  In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented without departing from the scope of the object of the present invention.

11 Workpiece 11a Front surface 11b Back surface 11c First processing mark (groove)
11d Second machining mark (groove)
11e Third processing mark (groove)
11f Fourth machining mark (groove)
13a 1st division planned line 13b 2nd division planned line 15 Device 17 Tape 19 Frame 21 Laser beam L1 1st position L2 2nd position L3 3rd position L4 4th position 2 Laser processing device 4 Chuck table 6 Laser processing unit 8 Camera (Imaging unit)

Claims (2)

By irradiating a plate-like workpiece divided into a plurality of areas by N (N is a natural number of 3 or more) division lines set at equal intervals along the division lines A processing method of a workpiece to be processed,
The distance from the planned division line located on the outermost side of the workpiece is 2 ⁿ × D (D is the distance between two adjacent planned division lines, and n is the maximum natural number satisfying 2 ⁿ <N). A first processing step of forming a processing mark on the workpiece by irradiating the laser beam to the division line existing at the first position represented;
After the first machining step, the division schedule is present at the k + 1th position where the distance from the kth position (k is a natural number equal to or less than ⁿ ) is represented by 2 ^nk × D × m (m is a natural number). Irradiating the laser beam to the division line selected from a line to form a processing mark on the workpiece, and k + 1 processing step,
The k + 1th processing step is sequentially performed for k from 1 to n,
In the (k + 1) -th processing step, the division-scheduled line that is not irradiated with the laser beam is selected in all the i-th processing steps in which i is a natural number equal to or less than k. .   The method of processing a workpiece according to claim 1, wherein the workpiece is a GaAs wafer.