TWI742272B - Laser processing method and laser processing device - Google Patents

Abstract

[Problem] Easily and quickly determine whether the groove shape of the laser processing groove is good or bad. [Solution] The wafer is irradiated with a pulsed laser beam with a Gaussian distribution of energy intensity through the mask to form a laser processing groove. Take pictures. The groove shape determination unit determines whether the groove shape of the laser processing groove is good or bad based on the shape of the light emission on the captured image. The mask position adjustment unit activates the mask moving mechanism according to the result of the determination of the groove shape to adjust the position of the mask relative to the pulse laser beam.

Description

Laser processing method and laser processing device Field of invention

The invention relates to a laser processing method and a laser processing device for laser processing of processed objects such as wafers.

Background of the invention

When the dicing blade is cut along the planned dividing line of the wafer to perform dicing, it is easy to peel off the film such as the Low-k film covering the wafer. In order to solve this problem, a method has been proposed in which a laser processing groove is formed along the planned dividing line of the wafer and then cut by a dicing blade (see, for example, Patent Document 1).

Prior art literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2005-209719

Summary of the invention

In the method disclosed in the above-mentioned Patent Document 1, the laser beam is irradiated on the wafer to form the laser processing groove, and the laser beam spot shape is shaped by a mask to form a prescribed Wide laser Processing groove.

However, there are cases where the relative position of the laser beam and the mask may deviate due to changes in time or temperature. When the position of the mask relative to the laser beam is deviated, the energy distribution of the irradiated laser beam will be deviated, which will cause the problem of distortion of the groove shape (cross-sectional shape) of the laser processing groove. In addition, when the groove shape of the laser processing groove is out of shape, there is a concern that the cutting knife will snake and be damaged during cutting by the cutting knife.

Therefore, in the past, the following method has been regularly performed: the dummy wafer is processed to determine whether the groove shape of the laser processing groove is good or bad, but the dummy wafer is regularly processed to determine the laser processing groove. Good and bad ways of ditch shape require a lot of labor and time. In addition, when an abnormality is found on the dummy wafer, the product wafer has already been processed in an abnormal state, so there is also the following problem: the damage of the product wafer processed before the abnormality is found on the fake workpiece is no longer possible avoid.

The present invention is an invention made in view of the above-mentioned facts, and its object is to make it possible to easily and quickly confirm the groove shape of the laser processing groove.

The present invention is a laser processing method that irradiates a processed object with a pulsed laser beam to form a laser processing groove. The mask is used to irradiate the processed object to form a laser processing groove, wherein the mask is formed to limit the passing range of the pulsed laser beam The slit; the photographed image forming step, in the implementation of the laser processing groove forming step, photographing the pulsed laser beam irradiating the processed object to produce light, and forming a photographed image; and groove shape determination step , According to the shape of the light emission on the captured image, determine whether the groove shape of the laser processing groove is good or bad.

Preferably, the laser processing method further includes a mask position adjustment step, and the mask position adjustment step is when the groove shape of the laser processing groove is determined to be defective by the groove shape determination step. Next, move the mask relative to the pulsed laser beam to adjust the position of the mask.

In addition, the present invention is a laser processing device that irradiates a processed object with a pulsed laser beam to form a laser processing groove, and includes: a holding mechanism to hold the processed object; a pulsed laser beam oscillating mechanism to generate a pair of oscillations by The processing object held by the holding mechanism is irradiated with a pulsed laser beam, and the pulsed laser beam is a pulsed laser beam with a Gaussian distribution of energy intensity; the condenser includes a condenser lens, and the condenser lens is The pulse laser beam oscillated by the pulse laser beam oscillating mechanism is condensed and focused on the workpiece held by the holding mechanism; the processing feed mechanism makes the holding mechanism and the pulse The laser beam irradiation mechanism relatively moves in the processing feed direction; the indexing feed mechanism makes the holding mechanism and the pulse laser beam irradiation mechanism relatively move in the indexing feed direction orthogonal to the processing feed direction ; Control mechanism to control the pulse laser beam irradiation mechanism, the processing feed mechanism, and the indexing feed mechanism; mask, with It is arranged between the pulse laser beam oscillation mechanism and the condenser lens, and is formed with a slit that limits the passing range of the pulse laser beam; and a photographing mechanism for photographing the pulse laser beam irradiating the processed object The light emission is generated and a photographed image is formed. The control mechanism has a groove shape determination unit that determines whether the groove shape of the laser processing groove is good or bad based on the shape of the light emission on the photographed image. .

Preferably, the laser processing apparatus includes a mask moving mechanism that moves the mask relative to the pulse laser beam, and the control mechanism further includes a determination based on the groove shape determination unit , A mask position adjustment part that activates the mask moving mechanism to adjust the position of the mask.

In the laser processing method and the laser processing device of the present invention, because a pulse laser beam with a Gaussian distribution of energy intensity is irradiated to the workpiece through a mask to form a laser processing groove, and the pulse laser beam is photographed The light emitted by the workpiece is irradiated to form a photographed image, and the shape of the laser processing groove is judged according to the shape of the light on the photographed image to determine whether the groove shape of the laser processing groove is good or bad, so the laser processing can be easily and quickly determined The groove shape is good or bad. Therefore, the doubt of wafer damage can be reduced.

1: Laser processing device

10: Abutment

11: Pillar

12: Overhang

2: keep the organization

21: Adsorption part

22: Work clamp table

23: Support

24: Fixture

3: Pulse laser beam irradiation mechanism

31: Pulse laser beam oscillation mechanism

311: Pulsed Laser Beam Oscillator

312: Repeat frequency setting mechanism

32: Condenser

321: Condenser lens

33: Two-way beam splitter

34: Mask

34a: slit

35: Mask moving mechanism

36: lighting mechanism

361: stroboscopic flash source

362: Aperture

363: lens

364: Direction Change Mirror

37: beam splitter

38: shooting agency

381: Combination lens

381a: Aberration correction lens

381b: imaging lens

382: camera element

4: Processing feed mechanism

5: Indexing feed mechanism

41, 51: Ball screw

42, 52: rail

43, 53: Pulse motor

44, 54: movable plate

6: Control mechanism

61: Pulse laser beam oscillation mechanism control unit

62: Lighting mechanism control department

63: Groove shape judging section

64: Mask position adjustment section

7: Calibration agency

C: Energy intensity distribution

G1, G2: Laser processing groove

LB: Pulsed laser beam

L1, L2: Optical axis

P1, P2: Take pictures

S1, S2: luminous shape

W: Wafer

X, Y, ±X, ±Y, ±Z: direction

Fig. 1 is a perspective view showing an example of a laser processing device.

Fig. 2 is a block diagram showing the structure of the laser processing device.

Fig. 3(a) is an explanatory diagram showing a state where the optical axis of the pulsed laser beam coincides with the optical axis of the mask. (b) is the thunder formed in the state shown in (a) A longitudinal cross-sectional view of an example of the groove shape of the shot groove.

Fig. 4(a) is an explanatory diagram showing a state where the optical axis of the pulsed laser beam does not coincide with the optical axis of the mask. (b) is a longitudinal cross-sectional view showing an example of the groove shape of the laser processing groove formed in the state of (a).

Fig. 5(a) is a plan view illustrating the shape of normal light emission. (b) is a plan view illustrating the shape of abnormal light emission.

The form used to implement the invention

The laser processing apparatus 1 shown in FIG. 1 is an apparatus that uses the pulse laser beam irradiation mechanism 3 to irradiate a wafer not shown in the figure held by the holding mechanism 2 with a pulse laser beam.

In the front part (-Y direction) of the base 10 of the laser processing device 1 is provided a processing feed mechanism 4 and an indexing feed mechanism 5, and the processing and feeding mechanism 4 is to position the holding mechanism 2 relative to the pulse laser beam The irradiation mechanism 3 is a mechanism for processing and feeding in the X axis direction (processing feed direction). The indexing feed mechanism 5 is to position the holding mechanism 2 relative to the pulse laser beam irradiation mechanism 3 in the Y axis direction (indexing feed Direction) Up indexing feed mechanism.

The machining feed mechanism 4 has a ball screw 41, a pair of guide rails 42, a pulse motor 43, and a movable plate 44. The ball screw 41 has an axis in the X-axis direction. The pair of guide rails 42 are arranged in parallel with the ball screw 41. The pulse motor 43 can rotate the ball screw 41, and the movable plate 44 screws the inner nut to the ball screw 41 and the bottom is slidably connected to 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 along with this, and moves in the X-axis direction. Move in the X-axis direction by the movable plate 44 The wafers held by the holding mechanism 2 can be processed and fed. The pulse motor 43 operates in accordance with the pulse signal supplied from the control mechanism 6. The control mechanism 6 counts the number of pulse signals supplied to the pulse motor 43 to identify the processing feed amount of the holding mechanism 2 and control the position of the holding mechanism 2 in the X-axis direction.

An indexing feed mechanism 5 is provided between the holding mechanism 2 and the processing feed mechanism 4. The indexing feed mechanism 5 makes the holding mechanism 2 and the pulse laser beam irradiation mechanism 3 in the Y-axis direction (indexing feed Direction) relative movement. That is, the holding mechanism 2 is formed to be able to move back and forth in the X-axis direction by the machining feed mechanism 4, and it can be made in the Y-axis orthogonal to the X-axis direction by the indexing feed mechanism 5 Indexing feed in the direction. The indexing feed mechanism 5 has a ball screw 51, a pair of guide rails 52, a pulse motor 53, and a movable plate 54. The ball screw 51 has an axis in the Y-axis direction. The pair of guide rails 52 are arranged in parallel with the ball screw 51. It is assumed that the pulse motor 53 can rotate the ball screw 51, and the movable plate 54 screws the inner nut to the ball screw 51 and the bottom is slidably connected to the guide rail 52. When the pulse motor 53 rotates the ball screw 51, the movable plate 54 is guided by the guide rail 52 along with this, and moves in the Y-axis direction. By moving the movable plate 54 in the Y-axis direction, the wafer held by the holding mechanism 2 can be indexed and fed. The pulse motor 53 operates in accordance with the pulse signal supplied from the control mechanism 6. The control mechanism 6 counts the number of pulse signals supplied to the pulse motor 53 to identify the indexing feed amount of the holding mechanism 2 and control the position of the holding mechanism 2 in the Y-axis direction.

The holding mechanism 2 has a working chuck table 22 and a cylindrical support part 23. The working chuck table 22 has a suction part 21 capable of sucking wafers. The cylindrical The support portion 23 in the shape of a circle rotatably supports the work clamp table 22 on the movable plate 54 of the indexing and feeding mechanism 5. Around the suction part 21 of the work chuck table 22, a jig 24 for fixing a ring frame (not shown) mounted on the wafer to the work chuck table 22 is arranged. The work chuck table 22 is rotated and driven by a pulse motor (not shown) in the supporting part 23. The wafer sucked and held by the suction part 21 on the work chuck table 22 rotates with the work chuck table 22. The control mechanism 6 counts the number of pulse signals supplied to the pulse motor to identify the rotation amount of the work chuck 22 and adjust the rotation amount of the wafer.

A support 11 is erected on the rear end (end in the +Y direction) of the base 10 of the laser processing device 1, and a pulse laser beam irradiation mechanism 3 is provided on the upper end of the support 11. Also, in this example, the control mechanism 6 is provided in the pillar portion 11. The upper end portion of the pillar portion 11 is provided with a protruding portion 12 that protrudes forward (-Y direction). A pulse laser beam oscillation mechanism 31 is provided in the extension portion 12. The lower surface near the front end of the extension 12 is arranged side by side in the X direction with a condenser 32 and a collimating mechanism 7. The condenser 32 is a pulsed laser beam oscillated from the pulsed laser beam oscillating mechanism 31 The light is condensed to the front surface of the wafer held by the holding mechanism 2, and the alignment mechanism 7 is used to adjust the relative position of the planned dividing line of the wafer and the condenser 32.

The calibration mechanism 7 has a function of photographing the wafer held by the holding mechanism 2. The captured image will be transmitted to the control mechanism 6. The control mechanism 6 drives the indexing and feeding mechanism 5 based on the image captured by the calibration mechanism 7 to thereby perform the alignment of the condenser 32 and the planned dividing line of the wafer in the Y-axis direction.

As shown in Figure 2, the pulse laser beam irradiation mechanism 3 is equipped with The pulse laser beam oscillation mechanism 31, the two-way beam splitter 33, and the condenser 32.

The pulse laser beam oscillation mechanism 31 has a pulse laser beam oscillator 311 and a repetition frequency setting mechanism 312. The pulse laser beam oscillator 311 oscillates to generate a pulse laser beam LB with a Gaussian distribution of energy intensity. The oscillation frequency of the pulse laser beam oscillator 311 can be set to a predetermined value by the repeat frequency setting mechanism 312.

The dichroic mirror 33 is arranged between the pulse laser beam oscillation mechanism 31 and the condenser 32. The dichroic mirror 33 has the following function: it reflects and guides the pulse laser beam LB generated by the pulse laser beam oscillation mechanism 31 to the condenser 32, and allows the pulse laser beam LB to have a wavelength other than the oscillation wavelength of the pulse laser beam LB. Light penetrates.

The condenser 32 has a condenser lens 321. The condensing lens 321 can condense the pulsed laser beam LB generated by the oscillation of the pulsed laser beam oscillating mechanism 31 and reflected in the dichroic mirror 33 and irradiate it onto the wafer W held by the holding mechanism 2.

A mask 34 is arranged between the dichroic mirror 33 and the condenser lens 321. The mask 34 is formed with a slit 34a that limits the passing range of the pulsed laser beam LB. The mask 34 is held by the mask moving mechanism 35. The mask moving mechanism 35 is controlled by the control mechanism 6 to move the mask 34 in a direction (XY direction) orthogonal to the Z direction, which is the irradiation direction of the pulsed laser beam LB.

In addition, the pulse laser beam irradiation mechanism 3 includes an illumination mechanism 36 and a beam splitter 37.

The lighting mechanism 36 has a stroboscopic light source 361, an aperture 362, a transparent The stroboscopic light source 361 emits illuminating light (white light), the stroboscopic light source 361 can specify the field of view of the illuminating light emitted from the stroboscopic light source 361, and the lens 363 can reduce the size of the illumination light emitted from the stroboscopic light source 361. The illuminating light is condensed, and the direction changing mirror 364 can reflect the illuminating light condensed by the lens 363 toward the beam splitter 37.

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

The imaging mechanism 38 has a combined lens 381 and an imaging element (CCD) 382 capable of capturing an image captured by the combined lens 381. The combined lens 381 is composed of an aberration correction lens 381a and an imaging lens 381b. The imaging mechanism 38 is based on the imaging element 382 receiving the light emitted by irradiating the pulsed laser beam LB on the wafer W and performing photoelectric conversion, thereby forming a captured image. The photographing mechanism 38 transmits the photographed image to the control mechanism 6.

The control mechanism 6 has a pulse laser beam oscillation mechanism control section 61, an illumination mechanism control section 62, a groove shape determination section 63, and a mask position adjustment section 64. The pulse laser beam oscillation mechanism control section 61 controls the pulse laser beam The oscillation mechanism 31 generates the oscillation of the pulse laser beam LB by the pulse laser beam oscillator 311. The illumination mechanism control section 62 controls the light emission operation of the stroboscopic light source 361 of the illumination mechanism 36, and the groove shape determination section 63 is to determine the good or bad of the groove shape of the laser processing groove based on the shape of the light emitted by irradiating the pulse laser beam LB on the wafer W (the shape of the light on the captured image), and the mask position is adjusted The part 64 is to actuate the mask moving mechanism 35 according to the result of the determination of the groove shape determining part 63 to adjust The position of the mask 34 relative to the pulsed laser beam LB.

The control mechanism 6 has at least CPU, ROM and RAM, and the CPU executes programs by using RAM in the work area to realize the pulse laser beam oscillation mechanism control section 61, the lighting mechanism control section 62, the groove shape determination section 63, and The function of the mask position adjustment unit 64.

For example, the RAM provided in the control mechanism 6 stores an image of the light emission during the normal time when the laser beam is irradiated, and the groove shape determining section 63 performs the function of the light emission shape at the normal time and the light emission shape on the captured image. Pattern matching is determined as follows: if the Q value (degree of coincidence) is above the threshold, it is good, and if it does not reach the threshold, it is bad.

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

(1) Laser processing groove formation steps

When the wafer W to be processed is sucked and held by the suction part 21 of the work chuck table 22, the work chuck table 22 is driven in the -X direction by the processing feed mechanism 4, thereby positioning the wafer W to the alignment Right below the institution 7. In addition, the alignment mechanism 7 photographs the wafer W, and based on the photographed image, the alignment of the planned dividing line of the wafer W and the Y-axis direction of the condenser 32 is performed.

Next, the processing feed mechanism 4 positions one end of the planned dividing line of the wafer W directly below the condenser 32. Then, the focal point of the pulse laser beam LB is aligned with the front surface of the wafer W to irradiate the pulse laser beam LB, and the work chuck 22 is moved in the X direction at a predetermined processing feed speed by the processing feed mechanism 4 Move on. If the work clamp table 22 moves to the wafer W After the other end of the planned dividing line of φ is located directly below the condenser 32, the irradiation of the pulsed laser beam LB is stopped and the movement of the work clamp table 22 is stopped. Thereby, a laser processing groove that does not penetrate the back surface of the wafer W is formed along the planned dividing line of the wafer W extending in a predetermined direction.

Whenever the laser processing of 1 line is finished, the work clamp table 22 is indexed and fed in the Y direction by the indexing feed mechanism 5 by an interval equivalent to the predetermined dividing line, and the laser is irradiated in the same manner as above. beam. In addition, after the laser processing of all the planned dividing lines of the wafer W extending in the predetermined direction is completed, the work 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. Thereby, a lattice-shaped laser processing groove is formed on the wafer W.

The above-mentioned laser processing is performed under the following processing conditions, for example.

Light source of pulse laser beam: YVO4 laser or YAG laser

Wavelength: 355nm

Repetition frequency: 50kHz

Average output: 3W

Condenser spot diameter: φ 10μm

Processing feed speed: 100mm/sec

In the above laser processing, the pulsed laser beam LB irradiated from the laser beam irradiating mechanism 3 can be shaped and irradiated to the wafer W by passing through the slit 34 a of the mask 34.

As shown in Figure 3(a), because the optical axis (center of the energy intensity distribution) L1 of the pulsed laser beam LB and the optical axis of the mask 34 (the slit 34a) When the center) L2 is the same, the hillside part of the energy intensity distribution (Gaussian distribution) C of the pulse laser beam LB is cut symmetrically with respect to the optical axis L1, and the pulse laser beam LB is not deviated in the energy intensity distribution. The wafer W is irradiated in an oblique state. Therefore, as shown in FIG. Injection processing groove G1. Although in the example of FIG. 3(b), a so-called bathtub-shaped laser processing groove G with vertical sides and a flat groove bottom is formed, it is also possible to form a groove bottom with a concave curved surface. The so-called U-shaped laser processing groove.

However, due to changes in time or temperature, there is a deviation in the mutual optical axis of the pulse laser beam oscillation mechanism 31 and the dichroic beam splitter 33, or the mutual optical axis between the dichroic beam splitter 33 and the mask 34 When a deviation occurs on the optical axis of, the optical axis L1 of the pulse laser beam LB and the optical axis L2 of the mask 34 will become inconsistent as shown in FIG. 4(a). If the mutual optical axes L1 and L2 of the laser beam LB and the mask 34 do not match, a deviation occurs in the energy intensity distribution C of the pulsed laser beam LB irradiated to the wafer W through the mask 34. In the example of FIG. 4(a), the optical axis L1 of the pulsed laser beam LB deviates to the right with respect to the optical axis L2 of the mask 34, and the energy intensity distribution of the pulsed laser beam LB passing through the slit 34a There is a skew on the surface. In this case, the energy intensity of the right part becomes larger than that of the left part in the irradiation spot. As a result, as shown in FIG. 4(b), a left-right asymmetrical laser-processed groove G2 with a deep right side and a shallow left side is formed. When the groove shape of the laser processing groove G2 is distorted in this way, there is a concern that the cutting blade may be damaged in the subsequent cutting by the cutting blade.

Therefore, in this laser processing apparatus 1, in the laser processing groove forming step of irradiating the laser beam LB to the wafer W through the mask 34 to form the laser processing groove, photographing the pulse laser beam LB is irradiated on The luminescence generated by the wafer W forms a captured image (the captured image forming step), and the shape of the luminescence on the captured image is then judged whether the groove shape of the laser processing groove is good or bad (the groove shape determining step) . As a result of this good and bad judgment, when it is judged that the groove shape of the laser processing groove is bad, the mask 34 is moved to adjust the horizontal position of the mask 34 (mask position adjustment step).

(2) Photographic image formation steps

In the captured image forming step, the stroboscopic light source 361 of the lighting mechanism 36 is made to emit light at a predetermined time. The light passes through the aperture 362, the lens 363, and the direction changing mirror 364 to be emitted, and passes through the beam splitter 37, the dichroic mirror 33, and the condenser 32 to irradiate the wafer W. In addition, the light emitted by irradiating the pulsed laser beam LB on the wafer W passes through the condenser lens 321, the dichroic mirror 33, and the beam splitter 37 to be guided to the imaging mechanism 38. The light guided to the imaging mechanism 38 passes through the combined lens 381 and forms an image on the imaging element 382. The photographing element 382 may perform photoelectric conversion on the imaged light to form a photographed image. The captured image will be transmitted to the control mechanism 6. The control mechanism 6 expands the captured image on the RAM. The captured images P1 and P2 shown in FIGS. 5(a) and 5(b) can be expanded on the RAM.

The captured image P1 of FIG. 5(a) was captured in a normal state, that is, when the optical axis L1 of the pulsed laser beam LB and the optical axis L2 of the mask 34 coincide with each other (refer to FIG. 3(a)) To the captured image, the captured image on P1 The light-emitting shape S1 is a shape in which the width in the Y direction (long side direction) is mostly uniform. On the other hand, the captured image P2 in FIG. 5(b) is in an abnormal state, that is, when the optical axis L1 of the pulsed laser beam LB and the optical axis L2 of the mask 34 deviate from each other (see FIG. 4(a) In the photographed image taken at the time of ), the light-emitting shape S2 on the photographed image P2 is a shape with a non-uniform width in the Y direction (long side direction).

(3) Groove shape determination step

In the groove shape judging step, the groove shape judging section 63 of the control mechanism 6 compares the images of the light emission shape S1 and S2 on the captured image developed on the RAM and the pre-stored image of the light emission shape at normal time. Implement pattern matching. In addition, if the degree of agreement between the two is equal to or higher than the threshold, it is judged as good, and if it does not reach the threshold, it is judged as bad. For example, in the case of FIG. 5(a), the degree of coincidence between the light emission shape S1 on the captured image P1 and the light emission shape at normal time is regarded as the threshold value or more, and the groove shape is judged to be good. On the other hand, in the case of FIG. 5( b ), the degree of coincidence between the light emission shape S2 on the captured image P2 and the light emission shape at the normal time is deemed to have not reached the threshold value, and the groove shape is determined to be defective.

(4) Steps to adjust mask position

In the mask position adjustment step, the mask position adjustment section 64 of the control mechanism 6 drives the mask moving mechanism 35 in response to the determination result in the groove shape determination step to adjust the mask 34 relative to the pulse laser beam The location of LB. This adjustment can be performed, for example, from the planned dividing line next to the planned dividing line for which the groove shape is judged to be defective. At this time, the mask position adjustment unit 64 controls the mask moving machine in accordance with the shape of the light on the captured image. The driving of the structure 35 adjusts the position of the mask 34 so that the shape of the light emission on the captured image becomes closer to the shape of the light emission at the normal time. For example, in the case of the captured image P2 shown in FIG. 5(b), the mask 34 is moved in the X direction so that the width (size in the Y direction) of the light-emitting shape S2 becomes uniform.

After adjusting the position of the mask 34 in this manner, when the wafer W is irradiated with a pulsed laser beam in the same manner as described above, a laser processing groove of a desired shape can be formed at a desired position. Then, the dicing blade can be cut into the laser processing groove to perform complete cutting, so as to divide the wafer W into individual wafers.

As described above, according to the present invention, the pulse laser beam LB with the energy intensity distribution C of the Gaussian distribution is irradiated to the wafer W through the mask 34 to form the laser processing groove, and the pulse laser beam LB is irradiated on The light emitted by the wafer W forms the photographed images P1, P2, and the shape of the laser processing groove is judged as good or bad based on the light-emitting shapes S1, S2 on the photographed images P1, P2, so that it is easy to And quickly determine whether the groove shape of the laser processing groove is good or bad. Therefore, it is not necessary to spend time equivalent to the inspection of the groove shape, and the operation efficiency of the laser processing apparatus 1 can be improved.

In addition, in this embodiment, the position of the mask 34 with respect to the pulse laser beam LB can be automatically adjusted in accordance with the result of determining whether the groove shape is good or bad. Therefore, it is possible to perform laser processing in an abnormal state. The damage of the wafer W is suppressed to a minimum, and the time required for the position adjustment of the mask 34 can be shortened to further improve productivity. Again, because of borrowing By adjusting the position of the mask 34, it becomes difficult to form an abnormal groove-shaped laser processing groove, so that the damage caused by the deformation of the cutting blade during cutting by the cutting blade can be reduced.

Furthermore, although in the above-mentioned embodiment, the wafer W is exemplified as the workpiece, the laser processing method and laser processing apparatus of the present invention can also be applied to laser processing of workpieces other than the wafer W .

In addition, although the captured image formation step, the groove shape determination step, and the mask position adjustment step can be performed in the laser processing of all the planned dividing lines of the wafer W, it is only necessary to perform, for example, about two lines for one wafer. The implementation of the laser groove processing period is sufficient.

1‧‧‧Laser processing device

2‧‧‧Maintaining Organization

3‧‧‧Pulse laser beam irradiation mechanism

31‧‧‧Pulse laser beam oscillation mechanism

311‧‧‧Pulse laser beam oscillator

312‧‧‧Repeat frequency setting mechanism

32‧‧‧Concentrator

321‧‧‧Condenser lens

33‧‧‧Two-way beam splitter

34‧‧‧Mask

34a‧‧‧Slit

35‧‧‧Mask moving mechanism

36‧‧‧Lighting mechanism

361‧‧‧Stroboscopic light source

362‧‧‧Aperture

363‧‧‧lens

364‧‧‧Direction change mirror

37‧‧‧Beam Splitter

38‧‧‧Filming agency

381‧‧‧combination lens

381a‧‧‧Aberration Correction Lens

381b‧‧‧imaging lens

382‧‧‧Camera Elements

6‧‧‧Control mechanism

61‧‧‧Pulse laser beam oscillation mechanism control unit

62‧‧‧Lighting Mechanism Control Department

63‧‧‧Ditch shape judging section

64‧‧‧Mask position adjustment part

LB‧‧‧Pulse laser beam

W‧‧‧wafer

Claims (4)

A laser processing method is to irradiate a processed object with a pulsed laser beam to form a laser processing groove. The laser processing method includes: a laser processing groove forming step to distribute the energy intensity into a pulsed laser beam with a Gaussian distribution , Irradiate the processed object through a mask to form a laser processing groove, wherein the mask is formed with a slit that limits the passing range of the pulsed laser beam; a photographed image forming step, in the laser processing groove forming step In the implementation, photographing the luminescence generated by irradiating the pulsed laser beam on the workpiece, and forming a photographed image; and the groove shape determination step, determining the laser processing according to the luminous shape on the photographed image The groove shape is good or bad. Such as the laser processing method of claim 1, which further includes a mask position adjustment step, which is a case where the groove shape of the laser processing groove has been determined to be defective by the groove shape determination step. Next, move the mask relative to the pulsed laser beam to adjust the position of the mask. A laser processing device that irradiates a processed object with a pulsed laser beam to form a laser processing groove. The laser processing device has: a holding mechanism to hold the processed object; a pulsed laser beam irradiation mechanism with a pulsed laser beam An oscillating mechanism and a condenser. The pulsed laser beam oscillating mechanism oscillates and generates a pulsed laser beam that irradiates the workpiece held by the holding mechanism, and the pulsed laser beam has a Gaussian energy intensity distribution The pulsed laser beam, the condenser includes a condenser lens, the condenser lens is to condense the pulsed laser beam generated by the oscillation of the pulsed laser beam oscillation mechanism, and condensed to the holding mechanism On the object to be held to be processed; a processing feed mechanism, which makes the holding mechanism and the pulse laser beam irradiation mechanism move relatively in the processing feed direction; an indexing feed mechanism, which makes the holding mechanism and the pulse laser beam The irradiation mechanism relatively moves in the indexing feed direction orthogonal to the processing feed direction; the control mechanism controls the pulse laser beam irradiation mechanism, the processing feeding mechanism, and the indexing feeding mechanism; the mask, It is arranged between the pulse laser beam oscillating mechanism and the condenser lens, and is formed with a slit that limits the passing range of the pulse laser beam; and a photographing mechanism for photographing the pulse laser beam irradiating the processed object The light emission is generated and a captured image is formed. The control mechanism has a groove shape determination unit that determines whether the groove shape of the laser processing groove is good or not based on the shape of the light emission on the captured image. bad. For example, the laser processing device of claim 3, which is provided with a mask moving mechanism that moves the mask relative to the pulse laser beam, and the control mechanism further includes a groove shape determination unit based on It is determined that the mask position adjustment unit operates the mask moving mechanism to adjust the position of the mask.

Images