KR20190130970A - Method for processing workpiece - Google Patents

Abstract

Provided is a method for processing a workpiece, which can suppress the occurrence of a processing defect when a plate type workpiece is processed by irradiating a laser beam. The method for processing the workpiece, processing the plate type workpiece including N (N is a natural number of 3 or more) estimated division lines which are equidistantly established, comprises: a first processing step of irradiating a laser beam onto a first estimated division line located at a first position where the distance from the estimated division line positioned at the outermost side of the workpiece is represented by 2^n×D (D is the distance between two adjacent first estimated division lines, and n is the greatest natural number satisfying 2^n<N) to form processing marks on the workpiece; and a (k+1)^th processing step of irradiating the laser beam onto the estimated division line selected from the first estimated division line located at a (k+1)^th position where the distance from a k^th position (k is a natural number of n or less) is represented by 2^(n-k)×D×m (m is a natural number) to form processing marks on the workpiece.

Description

Processing method of workpiece {METHOD FOR PROCESSING WORKPIECE}

This invention relates to the processing method of the to-be-processed object which processes a plate-shaped workpiece along a division plan line.

A device chip embedded in various electronic devices divides the surface of a wafer, which is a substrate, into a plurality of regions by a division scheduled line called a street, and forms a device such as an integrated circuit in each region. It is obtained by dividing along. For dividing the wafer, for example, a cutting device that rotates an annular cutting blade and cuts it into an object is used.

In cutting of the wafer using this cutting device, the wafer is mechanically cut by the rotating cutting blade. Therefore, if the load acting on a wafer from each of the side surface (surface) of one side of a cutting blade, and the side surface (rear surface) of the other side, for example, processing defects, such as a chip and a crack, are easy to generate | occur | produce in a wafer. . Moreover, when the bias of such a load becomes large, a cutting blade may break.

Therefore, a method of reducing the bias of the load acting between the cutting blade and the wafer by studying the order of cutting the cutting blade into the wafer has been proposed (see Patent Document 1, for example). In this method, the bias of the load acting between the cutting blade and the wafer is reduced by cutting the cutting blades into the dividing scheduled line of the wafer in the order in which the two small pieces generated by the split are approximately equal in area.

Instead of the above-mentioned cutting apparatus, the method of dividing a wafer using the laser processing apparatus which can irradiate the laser beam of the wavelength which shows absorptivity with respect to a wafer is also known (for example, refer patent document 2). In the method using this laser processing apparatus, a processing mark (groove) for dividing a wafer is formed by irradiating a pulsed laser beam along a wafer dividing line.

[Patent Document 1] Japanese Patent Application Laid-Open No. 4-245663 [Patent Document 2] Japanese Patent Application Laid-Open No. 10-305420

However, even when processing a wafer by the above-mentioned method using a laser processing apparatus, processing defects, such as a chip and a crack, may arise in the wafer.

This invention is made | formed in view of such a problem, Comprising: It aims at providing the processing method of the to-be-processed object which can suppress generation | occurrence | production of a machining defect, when irradiating a laser beam and processing a workpiece of plate shape.

According to one aspect of the present invention, a laser beam is irradiated along the division scheduled line with a plate-shaped workpiece divided into a plurality of areas by N division scheduled lines set at equal intervals (N is a natural number of 3 or more). A method for processing a workpiece to be processed by, wherein a distance from the scheduled splitting line located at the outermost side of the workpiece is 2 ⁿ x D (D is a distance between two adjacent split scheduled lines, and n is 2 ⁿ <N And a first processing step of forming a processing mark on the workpiece by irradiating the laser beam to the split line to be present at the first position represented by the maximum natural number satisfying. k where the distance is 2 ^nk × D from (k is a natural number less than n) × m (m is a natural number) the k + the division planned the laser in a line selected from the dividing lines to be present in the first position shown by Irradiating and forming a processing mark on the workpiece, and performing the k + 1 processing steps in sequence for k from 1 to n, and in the k + 1 processing step, A processing method of a workpiece is provided in which all the division scheduled lines, in which the laser beam is not irradiated, are selected in all the i th processing steps where i is a natural number of k or less.

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

In the processing method of the to-be-processed object which concerns on one aspect of this invention, after dividing into the area | region of the magnitude | size about which the process trace is formed in a to-be-processed object, the 1st dividing predetermined line located in the middle of the two process marks already formed. Since a new processing mark is formed by irradiating a laser beam on the surface, the region sandwiched between two already formed processing marks is divided into two small regions having the same volume by the newly formed processing marks.

Therefore, even if heat conduction generated at the time of irradiation of the laser beam is hindered by the processing marks already present, heat can be conducted equally in the two small regions. That is, since the temperature difference by heat at the time of a process becomes difficult to produce in one and the other of two small areas, the generation of the machining defect resulting from the conduction of the biased heat can be suppressed. As described above, according to one aspect of the present invention, there is provided a processing method of a workpiece, which can suppress the occurrence of machining defects when irradiating a laser beam with a plate-shaped workpiece.

1 is a perspective view illustrating a configuration example of a workpiece and the like.
2 is a perspective view showing a state in which a workpiece is processed.
3 is a plan view showing a workpiece processed along a division scheduled line existing in a first position.
FIG. 4 is a plan view showing a workpiece processed along a division scheduled line existing in a second position.
FIG. 5 is a plan view showing a workpiece processed along a division scheduled line existing in a third position.
FIG. 6 is a plan view showing a workpiece processed along a division scheduled line existing in a fourth position.

In the case of forming a processing mark such as a groove in a plate-shaped workpiece by irradiating a laser beam, for example, if the workpiece is processed sequentially from the end, machining defects such as chips or cracks are likely to occur in the workpiece. This phenomenon has a large temperature difference due to heat generated when the laser beam is irradiated between the two regions when one of the two regions divided by the boundary of the processing trace formed by the irradiation of the laser beam is sufficiently small. It is inferred to be due to the occurrence.

That is, it is considered that this problem can be solved if the heat generated during the irradiation of the laser beam can be equally conducted in the two regions divided by the processing marks. Therefore, in the present invention, after dividing the work piece into a region of a size such that a plurality of processing marks are formed, the laser beam is irradiated to a division scheduled line located in the middle of the two processing marks already formed and newly processed. Forms scars;

As a result, the region sandwiched between the two already existing processing marks is divided into two small regions having the same volume by the newly formed processing marks. Even if conduction of heat generated at the time of beam irradiation is disturbed, heat can be conducted equally in the two small regions.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment which concerns on one aspect of this invention is described with reference to an accompanying drawing. 1 is a perspective view showing a configuration example of a plate-shaped workpiece 11 or the like processed by the processing method of the workpiece 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 this workpiece 11 has a plurality of linear first divided scheduled lines 13a parallel to the first direction (A direction) and a second direction (B direction) that intersects the first direction. Is divided into a plurality of small regions by a plurality of linear second dividing scheduled lines 13b parallel to each other. That is, the first division scheduled line 13a and the second division scheduled line 13b cross each other.

In each small region, devices 15 such as ICs (Integrated Circuits) are provided. In addition, although the to-be-processed object 11 which the 1st direction and the 2nd direction are substantially perpendicular is shown in FIG. 1, the 1st direction and the 2nd direction should just intersect at least. That is, the first direction and the second direction do not have to be parallel.

In addition, there is no limitation on the material, shape, structure, size, and the like of the workpiece 11. For example, the workpiece 11 may be a substrate made of a material such as another semiconductor, ceramics, resin, or metal. Similarly, the type, quantity, shape, structure, size, arrangement, and the like of the device 15 are not limited. The device 15 may not be formed in the workpiece 11.

The tape 17 for dicing larger in diameter than the to-be-processed object 11 is adhere | attached on the back surface 11b side of this to-be-processed object 11. The outer circumferential portion of the tape 17 is adhered to the annular frame 19 having an approximately circular opening 19a. That is, the workpiece 11 is supported by the frame 19 via the tape 17.

In addition, in this embodiment, since the to-be-processed object 11 is processed on the surface 11a side, the tape 17 is adhere | attached on the back surface 11b side, but the to-be-processed object 11 is provided on the back surface 11b side. In the case of processing, what is necessary is just to adhere the tape 17 to the surface 11a side. In addition, when using the jig table which hold | maintains the to-be-processed object 11, you do not need to adhere the tape 17 to the to-be-processed object 11, for example.

2 is a perspective view showing a state in which the workpiece 11 is processed. In the processing method of the workpiece according to the present embodiment, the workpiece 11 is processed using, for example, the laser processing apparatus 2 shown in FIG. 2. This laser processing apparatus 2 is provided with the chuck table 4 for holding the to-be-processed object 11.

On a part of the upper surface of the chuck table 4, for example, a holding plate (not shown) made of a porous material is exposed. 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) through a suction path (not shown) or the like provided inside the chuck table 4. have.

A plurality of clamps (not shown) for fixing the annular frame 19 are provided around the chuck table 4. In addition, 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 moves in the X-axis direction (machining feed direction) and Y-axis direction (indexing feed direction) by this moving mechanism, and the rotational circumference is substantially parallel to the Z-axis direction (vertical direction) by the rotating mechanism. Rotate to

The laser processing unit 6 is arrange | positioned above the chuck table 4. The laser processing unit 6 irradiates and condenses the laser beam 21 pulse oscillated with a laser oscillator (not shown) at a predetermined position. The laser oscillator used in this embodiment is comprised so that the laser beam 21 of the wavelength which has the absorptivity with respect to the to-be-processed object 11 can be oscillated, and is suitable for the ablation process of the to-be-processed object 11.

The camera (imaging unit) 8 for image | photographing the to-be-processed object 11 etc. is arrange | positioned at the side of the laser processing unit 6. Based on the image acquired by this camera 8, for example, the angle which the 1st division planned line 13a (or 2nd division planned line 13b) of the to-be-processed object 11 and X-axis direction make will Adjusted.

In the processing method of the workpiece 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, after contacting the tape 17 adhered to the back surface 11b side of the workpiece 11 with the upper surface of the chuck table 4 (holding plate), the negative pressure of the suction source is applied. In addition, 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 was exposed upward.

After the workpiece 11 is held on the chuck table 4, the workpiece 11 is processed by irradiating a laser beam 21 (processing step). In addition, in this embodiment, although the process which processes the to-be-processed object 11 along the 1st dividing scheduled line 13a was demonstrated, the to-be-processed object 11 along the 2nd dividing scheduled line 13b by the same procedure. ) May be further processed. Of course, the to-be-processed object 11 can also be processed only along the 2nd dividing plan line 13b.

Specifically, first, N is the total number of the first divided scheduled lines 13a set in the work piece 11, D is the distance between two adjacent first divided scheduled lines 13a, and n is 2 ⁿ < First dividing schedule present at the first position represented by 2 ⁿ × D, the distance from the first dividing scheduled line 13a located at the outermost side of the workpiece 11 as the maximum natural number satisfying N. The workpiece 11 is processed by irradiating the line 13a with the laser beam 21 (first processing step).

In addition, since n satisfying 2 ⁿ <N is a natural number, the total number of first division scheduled lines 13a to be processed must be three or more. In addition, it is necessary to set the some 1st dividing predetermined line 13a at substantially equal intervals. That is, N pieces (N is a natural number of 3 or more) first division scheduled lines 13a are set in the workpiece 11 at substantially equal intervals.

In addition, there is no restriction | limiting in the number, arrangement | positioning, etc. of the 2nd division plan line 13b. Of course, when the workpiece 11 is to be processed along the second division scheduled line 13b by the same procedure as in the present embodiment, the second division scheduled line ( The condition of 13b) is set.

3 is a plan view showing the workpiece 11 processed along the division scheduled line 13a present at the first position L1. Below, the total number of the 1st dividing plan lines 13a set in the to-be-processed object 11 is demonstrated as 11 (namely, N = 11). In this case, the largest natural number n that satisfies 2 ⁿ <N is 3. Therefore, the distance from the 1st dividing plan line 13a (reference position L0) located in the outermost part of the to-be-processed object 11 to 1st position L1 is 8xD, as shown in FIG. Becomes

When irradiating the laser beam 21 along the 1st dividing predetermined line 13a which exists in 1st position L1, first, the chuck table 4 is moved, and the agent which exists in 1st position L1 is moved. The laser processing unit 6 is located above the extension line of one division plan line 13a. In addition, when the X-axis direction of the laser processing apparatus 2 and the 1st division plan line 13a of the to-be-processed object 11 are not parallel, the chuck table 4 is rotated and a 1st division plan line Adjust the direction of (13a).

Thereafter, the chuck table 4 is moved in the X-axis direction while irradiating the laser beam 21 having a wavelength having absorption to the workpiece 11 from the laser processing unit 6. Thereby, the 1st process mark (groove) 11c can be formed by irradiating the laser beam 21 to the 1st dividing predetermined line 13a which exists in the 1st position L1. In addition, there is no restriction | limiting in the depth of the 1st process trace 11c. For example, the 1st process mark 11c of the depth which divides (cuts) the to-be-processed object 11 may be formed.

After the 1st processing mark 11c is formed, the 1st position which exists in the 2nd position L2 whose distance from the 1st position L1 is represented by ^2n- 1xDxm (m is a natural number) is shown. The workpiece 11 is processed by irradiating a laser beam onto the division scheduled line 13a (second processing step).

FIG. 4 is a plan view showing the workpiece 11 processed along the division scheduled line 13a existing at the second position L2. As described above, the maximum natural number n that satisfies 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. 4, only the representative second position L2 is shown.

When irradiating the laser beam 21 along the 1st dividing schedule line 13a which exists in 2nd position L2, first, the chuck table 4 is moved, and any 1st dividing schedule which becomes an object will be carried out. The laser processing unit 6 is positioned above the extension line of the line 13a. And the chuck table 4 is moved to an X-axis direction, irradiating the laser beam 21 of the wavelength which has absorptivity with respect to the to-be-processed object 11 from the laser processing unit 6.

Thereby, the laser beam 21 can be irradiated to any one of the 1st scheduled dividing lines 13a as an object, and 11 d of 2nd process traces (grooves) can be formed. Moreover, there is no restriction | limiting also in the depth of this 2nd process trace 11d. Thereafter, the same procedure is repeated, and the second processing marks 11d are formed by irradiating the laser beam 21 to all the first division scheduled lines 13a as targets.

In addition, although the 2nd position L2 of the outside of the to-be-processed object 11 is also shown in FIG. 4, of course, you do not need to irradiate the laser beam 21 to this 2nd position L2. On the other hand, the distance from the 1st position L1 is represented by 4 * Dx2, and the laser beam is in the 1st division line 13a which exists in the 2nd position L2 which overlaps with the reference position L0. Investigate (21).

After the second processing mark 11d is formed, the first position at the third position L3 at which the distance from the second position L2 is represented by 2 ^{n −2} × D × m (m is a natural number) The laser beam in the first division scheduled line 13a (that is, the first processing step and the second processing step) in which neither the first processing mark 11c nor the second processing mark 11d is formed in the division scheduled line 13a. The workpiece 11 is processed by irradiating a laser beam to the first division scheduled line 13a that is not irradiated with the beam (third processing step).

FIG. 5: is a top view which shows the to-be-processed object 11 processed along the division plan line 13a which exists in 3rd position L3. As described above, the maximum natural number n that satisfies 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. 5, only the representative third position L3 is shown.

Laser beam along the 1st division line 13a in which neither the 1st process mark 11c nor the 2nd process mark 11d is formed among the 1st division plan line 13a which exists in 3rd position L3. When irradiating (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 division scheduled lines 13a. And the chuck table 4 is moved to an X-axis direction, irradiating the laser beam 21 of the wavelength which has absorptivity with respect to the to-be-processed object 11 from the laser processing unit 6.

Thereby, the 3rd process mark (groove) 11e can be formed by irradiating the laser beam 21 to any 1st division planned line 13a as an object. Moreover, there is no restriction | limiting also in the depth of this 3rd process trace 11e. Subsequently, the same procedure is repeated, and the 3rd processing mark 11e is formed by irradiating the laser beam 21 to all the 1st dividing | segment plan line 13a which becomes an object.

After the 3rd processing mark 11e is formed, the 1st position which exists in 4th position L4 in which the distance from 3rd position L3 is represented by ^2n-3 * Dxm (m is a natural number) is shown. The first division scheduled line 13a (that is, the first processing step) in which neither the first processing mark 11c, the second processing mark 11d nor the third processing mark 11e is formed in the division scheduled line 13a. , The second processing step and the third processing step, and the workpiece 11 is processed by irradiating the laser beam to the first divided scheduled line 13a that is not irradiated with the laser beam (fourth processing step).

FIG. 6: is a top view which shows the to-be-processed object 11 processed along the dividing line 13a which exists in 4th position L4. As described above, the maximum natural number n that satisfies 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. 6, only the representative fourth position L4 is shown.

The first division schedule, in which neither the first processing mark 11c, the second processing mark 11d nor the third processing mark 11e is formed in the first division scheduled line 13a existing in the fourth position L4. When irradiating the laser beam 21 along the line 13a, first, the chuck table 4 is moved, and the laser processing unit (above the extension line of any one first division scheduled line 13a as a target) 6). And the chuck table 4 is moved to an X-axis direction, irradiating the laser beam 21 of the wavelength which has absorptivity with respect to the to-be-processed object 11 from the laser processing unit 6.

Thereby, the 4th processing mark (groove) 11f can be formed by irradiating the laser beam 21 to any 1st division planned line 13a as an object. Moreover, there is no restriction | limiting also in the depth of this 4th process trace 11f. Thereafter, the same procedure is repeated, and the fourth processing marks 11f are formed by irradiating the laser beam 21 to all the first division scheduled lines 13a as targets. Thereby, the to-be-processed object 11 is processed along all the 1st dividing predetermined line 13a.

As mentioned above, in the processing method of the to-be-processed object which concerns on this embodiment, the area | region of the magnitude | size so that the process mark (1st process mark 11c, the 2nd process mark 11d) is formed in the to-be-processed object 11. After dividing by, the laser beam 21 is irradiated to the first split schedule line 13a positioned in the middle of the two already formed processing marks, and the new processing marks (the third processing mark 11e and the fourth processing mark) (11f)), the region sandwiched between the two already formed processing marks is divided into two small regions having the same volume by the newly formed grooves.

Therefore, even if heat conduction generated at the time of irradiation of the laser beam 21 is prevented by the processing marks already present, heat can be conducted equally in the two small regions. That is, since the temperature difference by the heat at the time of a process becomes difficult to produce in one side and the other of two small areas, the generation of the machining defect resulting from biased heat conduction can be suppressed.

In addition, this invention is not limited to description of the said embodiment, It can variously change and can implement. For example, in the above embodiment, the case where the total number of first division scheduled lines is 11 is mainly described. However, when the total number of first division scheduled lines is any N (N is a natural number of 3 or more), The workpiece 11 can be processed by the following procedure.

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

After the first machining step, from the first scheduled line to be divided at the k + 1 position where the distance from the kth position (k is a natural number less than or equal to n) is represented by 2 ^nk × D × m (m is a natural number) The laser beam is irradiated to the selected first divided line to be processed to form a working mark on the workpiece (k + 1 processing step).

This k + 1th processing step is performed in sequence for k from 1 to n. Further, in the k + 1th processing step, the division scheduled line to which the laser beam is not irradiated is selected in all the i'th processing steps where i is a natural number of k or less. Specifically, for example, in the fifth machining step, in the first machining step, the second machining step, the third machining step, and the fourth machining step, the division scheduled line 13a to which the laser beam is not irradiated is selected. do.

Moreover, in the said embodiment, although the to-be-processed object 11 is ablated by irradiating the laser beam 21 of the wavelength which has an absorptivity with respect to the to-be-processed object 11, the wavelength of the laser beam used for this ablation process There is no special limitation on the back. For example, even when using a laser beam having a wavelength that transmits to the workpiece 11, the workpiece 11 can be ablated by sufficiently concentrating the laser beam to cause multiphoton absorption.

In addition, in the said embodiment, although the process which processes the to-be-processed object 11 along the 1st dividing scheduled line 13a was demonstrated, the 1st dividing scheduled line 13a and the 2nd dividing scheduled line 13b will be described. You may process it alternately. In this case, for example, after the first processing step for processing the first division scheduled line 13a, a first processing step for processing the second division scheduled line 13b is performed, and thereafter, the first division schedule is performed. The workpiece 11 can be machined by a procedure of performing a second machining step for machining the line 13a.

In addition, the structure, method, etc. which concern on the said embodiment can be suitably changed and implemented, unless the deviation of the objective of this invention is deviated.

11: Workpiece 11a: Surface
11b: Back side 11c: First machining mark (groove)
11d: 2nd processing mark (groove) 11e: 3rd processing mark (groove)
11f: 4th processing scar (groove) 13a: first division scheduled line
13b: second division scheduled line 15: device
17: tape 19: frame
21: laser beam L1: first position
L2: second position L3: third position
L4: 4th position 2: laser processing apparatus
4: Chuck Table 6: Laser Processing Unit
8: camera (imaging unit)

Claims (2)

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

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