JP2018202468A - Laser processing method and laser processing device - Google Patents

Abstract

To easily and quickly determine a quality of a groove shape of a laser processing groove.SOLUTION: A pulse laser beam LB, of which an energy intensity distribution is Gaussian distribution, is radiated onto a wafer W via a mask 34a thereby forming a laser processing groove, and light emission, which occurs by irradiation of the wafer W with the pulse laser beam LB, is picked up by imaging means 38, thereby forming a picked-up image. A groove shape determination part 63 determines a quality of a groove shape of the laser processing groove based on a form of light emission on the picked-up image. A mask position adjustment part 64 operates mask transfer means 35 according to a determination result of the groove shape, and adjusts a position of a mask 34 to the pulse laser beam LB.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a laser processing method and a laser processing apparatus for laser processing a workpiece such as a wafer.

  When the cutting blade is cut along the wafer dividing line and dicing is performed, a film such as a low-k film coated on the wafer is easily peeled off. In order to solve this problem, there has been proposed a method of cutting with a cutting blade after forming a laser-processed groove along the division line of the wafer (see, for example, Patent Document 1).

JP 2005-209719 A

  In the method disclosed in Patent Document 1 described above, when forming a laser processing groove by irradiating a wafer with a laser beam, a laser processing groove having a predetermined groove width is formed by shaping the spot shape of the laser beam with a mask. To be formed.

  However, the relative position of the laser beam and the mask may shift due to changes over time or temperature. If the position of the mask with respect to the laser beam is deviated, the energy distribution of the irradiated laser beam is biased, and there is a problem that the groove shape (cross-sectional shape) of the laser processing groove is destroyed. If the shape of the laser processing groove is broken, the cutting blade may meander and be damaged during dicing by the cutting blade.

  Therefore, conventionally, a dummy wafer is periodically processed to determine whether the groove shape of the laser processing groove is good or bad. However, the dummy wafer is periodically processed to check the groove shape of the laser processing groove. It was very time-consuming to judge. In addition, since the product wafer is already processed in an abnormal state when an abnormality is found in the dummy wafer, there is a problem that damage to the processed product wafer is inevitable before the abnormality is detected in the dummy workpiece. is there.

  The present invention has been made in view of the above facts, and an object of the present invention is to make it possible to easily and quickly confirm the shape of a laser-processed groove.

The present invention is a laser processing method for forming a laser processing groove by irradiating a workpiece with a pulsed laser beam, and restricts a passing range of the pulsed laser beam having a Gaussian energy intensity distribution. A laser processing groove forming step for forming a laser processing groove by irradiating the workpiece through a mask in which slits are formed, and the workpiece is irradiated with the pulse laser beam during the laser processing groove forming step. A captured image forming step of capturing the emitted light to form a captured image, and a groove shape determining step of determining the quality of the groove shape of the laser processing groove based on the shape of the light emission on the captured image; .
In this laser processing method, a mask position for adjusting the position of the mask by moving the mask with respect to the pulse laser beam when the groove shape determination step determines that the groove shape of the laser processing groove is NO It is desirable to further include an adjustment step.

Further, the present invention is a laser processing apparatus for forming a laser processing groove by irradiating a workpiece with a pulsed laser beam, the holding means for holding the workpiece, and the workpiece held by the holding means A pulsed laser beam oscillating means for oscillating a pulsed laser beam having a Gaussian distribution of energy intensity, and a target that is held by the holding means by condensing the pulsed laser beam emitted from the pulsed laser beam oscillating means A condenser including a condensing lens for condensing on a workpiece, a processing feed means for relatively moving the holding means and the pulse laser beam irradiation means in the processing feed direction, the holding means and the pulse laser beam irradiation means Indexing feed means for relatively moving in the indexing feed direction orthogonal to the machining feed direction, the pulse laser beam irradiation means, and the machining feed means A control means for controlling the index feed means; a mask provided between the pulse laser beam oscillating means and the condenser lens and formed with a slit for restricting the passage range of the pulse laser beam; and Imaging means for imaging light emission generated by irradiating a workpiece with a pulse laser beam and forming a captured image, and the control means is configured to control the laser based on the shape of the light emission on the captured image. A groove shape determining unit that determines the quality of the groove shape of the processed groove is provided.
The laser processing apparatus includes a mask moving unit that moves the mask with respect to the pulsed laser beam, and the control unit operates the mask moving unit based on the determination by the groove shape determining unit. It is desirable to further include a mask position adjustment unit that adjusts the position of the mask.

  In the laser processing method and the laser processing apparatus according to the present invention, the workpiece is irradiated with a pulsed laser beam having a Gaussian distribution of energy intensity through a mask to form a laser processing groove, and the workpiece is irradiated with the pulsed laser beam. The captured light emission is imaged to form a captured image, and the quality of the laser processing groove is determined based on the shape of the light emission on the captured image. And it can be determined quickly. Therefore, the possibility that the wafer is damaged can be reduced.

It is a perspective view which shows an example of a laser processing apparatus. It is a block diagram which shows the structure of a laser processing apparatus. FIG. (A) is explanatory drawing which shows the state in which the optical axis of a pulse laser beam corresponds with the optical axis of a mask. (B) is a longitudinal cross-sectional view which shows an example of the groove shape of the laser processing groove formed in the state of (a). (A) is explanatory drawing which shows the state which the optical axis of a pulse laser beam does not correspond with the optical axis of a mask. (B) is a longitudinal cross-sectional view which shows an example of the groove shape of the laser processing groove formed in the state of (a). (A) is a top view which illustrates the shape of normal light emission. FIG. 6B is a plan view illustrating an abnormal light emission shape.

  A laser processing apparatus 1 shown in FIG. 1 is an apparatus that irradiates a wafer (not shown) held by a holding unit 2 with a pulsed laser beam irradiation unit 3.

  At the front part (−Y direction) of the base 10 of the laser processing apparatus 1, a processing feed means 4 for processing and feeding the holding means 2 to the pulse laser beam irradiation means 3 in the X-axis direction (processing feed direction); Indexing feeding means 5 for indexing and feeding the holding means 2 to the pulse laser beam irradiation means 3 in the Y-axis direction (indexing feeding direction) is provided.

  The processing feed means 4 includes a ball screw 41 having an axis in the X-axis direction, a pair of guide rails 42 arranged in parallel to the ball screw 41, a pulse motor 43 that rotates the ball screw 41, and an internal nut that is a ball screw. 41 and a movable plate 44 whose bottom portion is in sliding contact with the guide rail 42. When the pulse motor 43 rotates the ball screw 41, the movable plate 44 is guided by the guide rail 42 and moves in the X-axis direction. As the movable plate 44 moves in the X-axis direction, the wafer held by the holding means 2 is processed and fed. The pulse motor 43 is operated by a pulse signal supplied from the control means 6. The control unit 6 counts the number of pulse signals supplied to the pulse motor 43 to recognize the machining feed amount of the holding unit 2 and controls the position of the holding unit 2 in the X-axis direction.

  Between the holding means 2 and the processing feed means 4, there is provided an indexing feed means 5 for relatively moving the holding means 2 and the pulse laser beam irradiation means 3 in the Y-axis direction (index feed direction). That is, the holding means 2 can be reciprocated in the X-axis direction by the processing feed means 4 and can be indexed and fed in the Y-axis direction orthogonal to the X-axis direction by the index feed means 5. The index feeding means 5 includes a ball screw 51 having an axis in the Y-axis direction, a pair of guide rails 52 arranged in parallel to the ball screw 51, a pulse motor 53 that rotates the ball screw 51, and an internal nut that is a ball screw. And a movable plate 54 having a bottom portion slidably contacting the guide rail 52. When the pulse motor 53 rotates the ball screw 51, the movable plate 54 is guided by the guide rail 51 and moves in the Y-axis direction. As the movable plate 54 moves in the Y-axis direction, the wafer held by the holding means 2 is indexed and fed. The pulse motor 53 is operated by a pulse signal supplied from the control means 6. The control means 6 counts the number of pulse signals supplied to the pulse motor 53 to recognize the index feed amount of the holding means 2 and controls the position of the holding means 2 in the Y-axis direction.

  The holding unit 2 includes a chuck table 22 having an adsorption unit 21 that adsorbs a wafer, and a columnar support unit 23 that rotatably supports the chuck table 22 on the movable plate 54 of the index feeding unit 5. A clamp 24 for fixing a ring frame (not shown) mounted on the wafer to the chuck table 22 is disposed around the chucking portion 21 of the chuck table 22. The chuck table 22 is rotationally driven by a pulse motor (not shown) in the support portion 23. Along with the rotation of the support table 22, the wafer sucked and held by the suction portion 21 on the support table 22 rotates. The control means 6 counts the number of pulse signals supplied to the pulse motor, thereby recognizing the rotation amount of the chuck table 22 and adjusting the rotation amount of the wafer.

  A support column 11 is erected on the rear end (+ Y direction end) of the base 10 of the laser processing apparatus 1, and the pulse laser beam irradiation means 3 is provided on the upper end of the support 11. In this example, the control means 6 is provided in the column 11. A projecting portion 12 projecting forward (−Y direction) is provided at the upper end portion of the support column portion 11. A pulse laser beam oscillating means 31 is provided in the overhanging portion 12. On the lower surface in the vicinity of the tip of the overhanging portion 12, a condenser 32 for condensing the pulse laser beam oscillated from the pulse laser beam oscillating means 31 onto the surface of the wafer held by the holding means 2, and a schedule for dividing the wafer Alignment means 7 for adjusting the relative position of the line and the light collector 32 is provided side by side in the X direction.

  The alignment unit 7 has a function of imaging the wafer held by the holding unit 2. The captured image is sent to the control means 6. The control means 6 drives the indexing and feeding means 5 based on the image picked up by the alignment means 7, thereby aligning the condenser 32 and the wafer division planned line in the Y-axis direction.

  As shown in FIG. 2, the pulse laser beam irradiation means 3 includes a pulse laser beam oscillation means 31, a dichroic mirror 33, and a condenser 32.

  The pulse laser beam oscillating means 31 has a pulse laser beam oscillator 311 and a repetition frequency setting means 312. The pulse laser beam oscillator 311 oscillates a pulse laser beam LB whose energy intensity distribution is Gaussian distribution. The oscillation frequency of the pulse laser beam oscillator 311 is set to a predetermined value by the repetition frequency setting means 312.

  The dichroic mirror 33 is provided between the pulse laser beam oscillating means 31 and the condenser 32. The dichroic mirror 33 has a function of reflecting and guiding the pulse laser beam LB oscillated from the pulse laser beam oscillating means 31 to the condenser 32 and transmitting light having a wavelength other than the oscillation wavelength of the pulse laser beam LB. ing.

  The condenser 32 has a condenser lens 321. The condensing lens 321 condenses the pulse laser beam LB oscillated from the pulse laser beam oscillating means 31 and reflected by the dichroic mirror 33 and irradiates the wafer W held by the holding means 2.

  A mask 34 is disposed between the dichroic mirror 33 and the condenser lens 321. The mask 34 is formed with a slit 34a that regulates the passage range of the pulse laser beam LB. The mask 34 is held by a mask moving means 35. The mask moving means 35 is controlled by the control means 6 to move the mask 34 in a direction (XY direction) orthogonal to the Z direction that is the irradiation direction of the pulse laser beam LB.

  The pulse laser beam irradiation means 3 includes an illumination means 36 and a beam splitter 37.

  The illumination unit 36 includes a strobe light source 361 that emits illumination light (white light), a diaphragm 362 that defines the field size of the illumination light emitted from the strobe light source 361, and a lens that collects the illumination light that has passed through the diaphragm 362. 363 and a direction changing mirror 364 that reflects the illumination light collected by the lens 363 toward the beam splitter 37.

  The beam splitter 37 guides the illumination light reflected by the direction changing mirror 364 of the illumination unit 36 to the dichroic mirror 33 and branches the light from the wafer W held by the holding unit 2 toward the imaging unit 38.

  The imaging means 38 includes a group lens 381 and an image sensor (CCD) 382 that captures an image captured by the group lens 381. The combined lens 381 includes an aberration correction lens 381a and an imaging lens 381b. The image pickup means 38 forms a picked-up image by receiving light emitted by the image pickup device 382 and photoelectrically converting light emitted when the wafer W is irradiated with the pulse laser beam LB. The imaging unit 38 sends the captured image to the control unit 6.

  The control means 6 controls the light emission operation of the pulse laser beam oscillation means controller 61 for controlling the oscillation operation of the pulse laser beam LB by the pulse laser beam oscillator 311 of the pulse laser beam oscillation means 31 and the strobe light source 361 of the illumination means 36. A groove shape for determining the quality of the groove shape of the laser processing groove based on the illumination means control unit 62 that performs the irradiation and the light emission shape (the light emission shape on the captured image) generated by irradiating the wafer W with the pulse laser beam LB The determination unit 63 includes a mask position adjustment unit 64 that operates the mask moving unit 35 based on the determination result of the groove shape determination unit 63 to adjust the position of the mask 34 with respect to the pulse laser beam LB.

  The control means 6 includes at least a CPU, a ROM, and a RAM. When the CPU executes a program using the RAM as a work area, the pulse laser beam oscillation means control section 61, the illumination means control section 62, and the groove shape determination are performed. The functions of the unit 63 and the mask position adjustment unit 64 are realized.

  For example, the RAM included in the control unit 6 stores a normal light emission image during laser beam irradiation, and the groove shape determination unit 63 determines the normal light emission shape and the light emission shape on the captured image. If the Q value (coincidence) is equal to or higher than the threshold value, it is determined to be good, and if it is less than the threshold value, it is determined to be negative.

  Next, the operation of the laser processing apparatus 1 configured as described above will be described. The following operations are generally performed under the control of the control means 6.

(1) Laser processing groove forming step When the wafer W, which is a workpiece, is sucked and held by the suction portion 21 of the chuck table 22, the chuck table 22 is driven in the -X direction by the processing feeding means 4, whereby the wafer W Is positioned directly below the alignment means 7. Then, the wafer W is imaged by the alignment means 7, and based on the captured image, the planned division line of the wafer W and the condenser 32 are aligned in the Y-axis direction.

  Next, the processing feed means 4 positions one end of the division planned line of the wafer W directly below the light collector 32. Then, the chuck table 22 is moved in the X direction at a predetermined processing feed speed while the pulse laser beam LB is irradiated with the focusing point of the pulse laser beam LB aligned with the surface of the wafer W. When the chuck table 22 moves until the other end of the line to be divided of the wafer W is positioned directly below the condenser 32, the irradiation of the pulse laser beam LB is stopped and the movement of the chuck table 22 is stopped. As a result, a laser processing groove that does not penetrate to the back surface of the wafer W is formed along a predetermined division line extending in a predetermined direction of the wafer W.

  Each time the laser processing for one line is completed, the index table 5 indexes and feeds the chuck table 22 by the interval of the scheduled division lines, and irradiates the laser beam in the same manner as described above. Then, when the laser processing of all the scheduled division lines extending in the predetermined direction of the wafer W is completed, the chuck table 22 is rotated by 90 °. Then, the same laser processing is performed on the planned dividing line extending in the direction orthogonal to the predetermined direction. As a result, laser processing grooves are formed on the wafer W in a lattice pattern.

The laser processing is performed, for example, under the following processing conditions.
Pulse laser beam light source: YVO4 laser or YAG laser Wavelength: 355 nm
Repetition frequency: 50 kHz
Average output: 3W
Condensing spot diameter: φ10μm
Processing feed rate: 100 mm / sec

  In the laser processing described above, the pulse laser beam LB irradiated from the laser beam irradiation unit 3 is shaped by passing through the slit 34a of the mask 34 and is irradiated onto the wafer W.

  As shown in FIG. 3A, when the optical axis (center of energy intensity distribution) L1 of the pulse laser beam LB coincides with the optical axis (center of the slit 34a) L2 of the mask 34, the pulse laser beam LB Since the base portion of the energy intensity distribution (Gaussian distribution) C is cut off symmetrically with respect to the optical axis L1, the pulse laser beam LB is irradiated onto the wafer W in a state where the energy intensity distribution is not biased. As shown in the drawing, a laser-processed groove G1 having a groove shape that is symmetric with respect to the optical axis L2 of the mask 34 (left-right symmetric in the illustrated example) is formed on the wafer W. In the example of FIG. 3B, a so-called bathtub-shaped laser processing groove G having a vertical side surface and a flat groove bottom is formed, but a so-called U-shaped laser processing groove having a concave curved surface is formed. It is also possible.

  However, if the optical axis of the pulse laser beam oscillating means 31 and the dichroic mirror 33 is deviated from each other or the optical axis of the dichroic mirror 33 and the mask 34 is deviated due to a change with time or temperature, FIG. As shown in (a), the optical axis L1 of the pulse laser beam LB does not coincide with the optical axis L2 of the mask. If the optical axes L1 and L2 of the laser beam LB and the mask 34 do not coincide with each other, the energy intensity distribution C of the pulse laser beam LB irradiated onto the wafer W through the mask 34 is biased. In the example of FIG. 4A, the optical axis L1 of the pulse laser beam LB is shifted to the right side with respect to the optical axis L2 of the mask 34, thereby biasing the energy intensity distribution of the pulse laser beam LB passing through the slit 34a. Has occurred. In this case, the energy intensity in the right side portion is larger than that in the left side portion in the irradiation spot. As a result, as shown in FIG. 4B, a laser processing groove G2 having an asymmetrical groove shape with a right side deep and a left side shallow is formed. If the groove shape of the laser processing groove G2 collapses in this way, the cutting blade may be damaged during dicing by the subsequent cutting blade.

  Therefore, in the laser processing apparatus 1, in the laser processing groove forming step of forming the laser processing groove by irradiating the wafer W with the pulse laser beam LB through the mask 34, the pulse W laser beam LB is applied to the wafer W. The generated light emission is imaged to form a captured image (captured image forming step), and the quality of the groove shape of the laser processing groove is determined based on the shape of the light emission on the captured image (groove shape determination step). As a result of the quality determination, if it is determined that the shape of the laser processed groove is NO, the mask 34 is moved to adjust the horizontal position of the mask 34 (mask position adjustment step).

(2) Captured image forming step In the captured image forming step, the strobe light source 361 of the illumination unit 36 is caused to emit light at a predetermined timing. The light is emitted through a diaphragm 362, a lens 363, and a direction conversion mirror 364, and is irradiated onto the wafer W through a beam splitter 37, a dichroic mirror 33, and a condenser 32. The light emitted when the wafer W is irradiated with the pulse laser beam LB is guided to the imaging means 38 via the condenser lens 321, the dichroic mirror 33, and the beam splitter 37. The light guided to the image pickup means 38 is imaged on the image pickup device 382 via the group lens 381. The image sensor 382 photoelectrically converts the imaged light to form a captured image. The captured image is sent to the control means 6. The control means 6 develops the captured image on the RAM. On the RAM, for example, captured images P1 and P2 as shown in FIGS. 5A and 5B are developed.

  The captured image P1 of FIG. 5A is normal, that is, when the optical axis L1 of the pulse laser beam LB and the optical axis L2 of the mask 34 are coincident with each other (see FIG. 3A). This is a captured image, and the light emission shape S1 on the captured image P1 has a shape whose width in the Y direction (longitudinal direction) is mostly uniform. On the other hand, the captured image P2 in FIG. 5B is in an abnormal state, that is, when the optical axis L1 of the pulse laser beam LB and the optical axis L2 of the mask 34 are shifted from each other (see FIG. 4A). The light emission shape S2 on the captured image P2 has a shape in which the width in the Y direction (longitudinal direction) is not uniform.

(3) Groove shape determination step In the groove shape determination step, the groove shape determination unit 63 of the control means 6 is configured to store the images of the light emission shapes S1 and S2 on the captured image developed on the RAM and the normal state stored in advance. Pattern matching with the image of the light emission shape is performed. If the degree of coincidence between the two is greater than or equal to a threshold value, it is determined to be good. For example, in the case of FIG. 5A, the groove shape is determined to be good, assuming that the degree of coincidence between the light emission shape S1 on the captured image P1 and the normal light emission shape is equal to or greater than a threshold value. On the other hand, in the case of FIG. 5B, it is determined that the groove shape is NO, assuming that the degree of coincidence between the light emission shape S2 on the captured image P2 and the normal light emission shape is less than the threshold value.

(4) Mask Position Adjustment Step In the mask position adjustment step, the mask position adjustment unit 64 of the control means 6 drives the mask moving means 35 according to the determination result in the groove shape determination step, and the mask 34 for the pulse laser beam LB. Adjust the position. This adjustment is performed, for example, from the scheduled division line next to the planned division line determined to have no groove shape. At that time, the mask position adjustment unit 64 controls the driving of the mask moving unit 35 according to the light emission shape on the captured image so that the light emission shape on the captured image becomes closer to the normal light emission shape. The position of the mask 34 is adjusted. For example, in the case of the captured image P2 shown in FIG. 5B, the mask 34 is moved in the X direction so that the width (dimension in the Y direction) of the light emission shape S2 is uniform.

  After adjusting the position of the mask 34 in this way, the laser processing groove having a desired shape can be formed at a desired position by irradiating the wafer W with the pulse laser beam in the same manner as described above. Then, the wafer W is divided into individual chips by cutting a cutting blade into the laser processing groove and cutting it completely.

  As described above, according to the present invention, the pulse laser beam LB is formed on the wafer while forming the laser processing groove by irradiating the wafer W with the pulse laser beam LB having the Gaussian energy intensity distribution C through the mask 34. Light emission generated by irradiation with W is imaged to form captured images P1 and P2, and the quality of the groove shape of the laser processing groove is determined based on the light emission shapes S1 and S2 on the captured images P1 and P2. Therefore, it is possible to easily and quickly determine the quality of the laser processing groove. Therefore, it does not require time only for the inspection of the groove shape, and the operating efficiency of the laser processing apparatus 1 is improved.

  In the present embodiment, the position of the mask 34 with respect to the pulse laser beam LB is automatically adjusted according to the determination result of the groove shape. Therefore, damage to the wafer W due to laser processing in an abnormal state is minimized. In addition, the productivity can be further improved by reducing the time required to adjust the position of the mask 34. Further, by adjusting the position of the mask 34, it becomes difficult to form an abnormal groove-shaped laser-processed groove, so that damage due to deformation of the cutting blade during dicing by the cutting blade is reduced.

  In the above-described embodiment, the wafer W is exemplified as the workpiece. However, the laser processing method and the laser processing apparatus according to the present invention can be applied to laser processing of a workpiece other than the wafer W.

  Further, the imaged image forming step, the groove shape determining step, and the mask position adjusting step can be performed in the laser processing of all the divided lines of the wafer W, but for example, about two lines of laser per wafer. It is sufficient if it is carried out during the grooving.

DESCRIPTION OF SYMBOLS 1: Laser processing apparatus 10: Base 11: Support part 12: Overhang part 2: Holding means 21: Adsorption part 22: Chuck table 23: Support part 24: Clamp 3: Laser beam irradiation means 31: Pulse laser beam oscillation means 311: Pulse laser beam oscillator 312: Repetitive frequency setting means 32: Condenser 321: Condensing lens 33: Dichroic mirror 34: Mask 34a: Slit 35: Mask moving means 36: Illuminating means 361: Strobe light source 362: Aperture 363: Lens 364: Direction changing mirror 37: Beam splitter 38: Imaging means 381: Pair lens 381a: Aberration correction lens 381b: Imaging lens 382: Imaging element 4: Processing feed means 41: Ball screw 42: Guide rail 43: Pulse motor 44: Movable plate 5: Index feeding means 51: Ball G 52: Guide rail 53: Pulse motor 54: Movable plate 6: Control means 61: Pulse laser beam oscillation means control section 62: Illumination means control section 63: Groove shape determination section 64: Mask position adjustment section 7: Alignment means G1, G2: Laser processing groove LB: Pulsed laser beam L1: Optical axis L2: Optical axis P1: Captured image P2: Captured image S1: Shape of light emission S2: Shape of light emission

Claims (4)

A laser processing method for forming a laser processing groove by irradiating a workpiece with a pulsed laser beam,
A laser processing groove forming step for forming a laser processing groove by irradiating a workpiece with a pulse laser beam having an energy intensity distribution of a Gaussian distribution through a mask in which a slit for restricting a passage range of the pulse laser beam is formed; ,
An imaging image forming step of imaging a light emission generated by irradiating the workpiece with the pulsed laser beam during the laser processing groove forming step to form a captured image;
A groove shape determining step for determining whether or not the groove shape of the laser processed groove is good based on the shape of the light emission on the captured image. The laser processing method according to claim 1,
A mask position adjusting step of adjusting the position of the mask by moving the mask with respect to the pulse laser beam when the groove shape determining step determines that the groove shape of the laser processing groove is NO , Laser processing method. A laser processing apparatus for forming a laser processing groove by irradiating a workpiece with a pulsed laser beam,
Holding means for holding the workpiece;
A pulse laser beam oscillating unit that oscillates a pulse laser beam having a Gaussian distribution of energy intensity applied to the workpiece held by the holding unit, and the pulse laser beam oscillated from the pulse laser beam oscillating unit is condensed. And a condenser including a condenser lens for condensing on the workpiece held by the holding means, and a pulsed laser beam irradiation means having
A machining feed means for relatively moving the holding means and the pulsed laser beam irradiation means in a machining feed direction;
Indexing feeding means for relatively moving the holding means and the pulsed laser beam irradiation means in an indexing feeding direction orthogonal to the machining feeding direction;
Control means for controlling the pulse laser beam irradiation means, the processing feed means and the index feed means;
A mask formed between the pulse laser beam oscillation means and the condenser lens and formed with a slit for restricting the passage range of the pulse laser beam;
Imaging means for imaging light emission generated by irradiating the workpiece with the pulsed laser beam to form a captured image;
The laser processing apparatus, wherein the control unit includes a groove shape determination unit that determines the quality of the groove shape of the laser processing groove based on the shape of the light emission on the captured image. It is a laser processing apparatus of Claim 3, Comprising:
A mask moving means for moving the mask with respect to the pulsed laser beam;
The laser processing apparatus, further comprising: a mask position adjusting unit that adjusts a position of the mask by operating the mask moving unit based on the determination by the groove shape determining unit.

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