KR102616529B1 - Laser processing apparatus - Google Patents

Abstract

The object of the present invention is to provide a laser processing device that does not interfere with the irradiation of the laser beam to the workpiece when processing a plate-shaped workpiece by irradiating the laser beam.
A laser processing device 2, which includes a chuck table 34 holding a plate-shaped workpiece 10, and a concentrator 86 that irradiates a laser beam LB to the workpiece 10 held on the chuck table 34. ), a laser beam irradiation unit 8 including a processing transfer unit 50 that relatively processes and transfers the chuck table 34 and the concentrator 86, and is located immediately below the concentrator 86, and the workpiece ( 10) includes a liquid layer generator 40 that generates a layer of liquid W on the upper surface, and the liquid layer generator 40 is transparent to allow the passage of the laser beam LB emitted by the concentrator 86. A side wall 422 having a lower end portion that hangs down from the outside of the ceiling wall 421 and forms a gap between the ceiling wall 421 including the plate 423 and the transparent plate 423 and the workpiece 10. ) and a liquid supply unit 43 that supplies liquid W to the internal space 422a of the case 42 and fills the internal space 422a with the liquid W. A liquid spray nozzle 422e is disposed in the case 42 for spraying liquid toward the irradiation position of the laser beam LB irradiated to the workpiece 10.

Description

Laser processing device {LASER PROCESSING APPARATUS}

The present invention relates to a laser processing device that processes a plate-shaped workpiece by irradiating a laser beam.

A wafer on which a plurality of devices such as ICs and LSIs are divided by division lines and formed on the surface is divided into individual device chips by a laser processing device, and the divided device chips are used in mobile phones, personal computers, lighting equipment, etc. It is used in electrical devices.

The laser processing device is of a type that forms a groove that becomes the starting point of division through ablation processing in which a convergence point of a laser beam with a wavelength that is absorbent to the workpiece is placed on the surface of the workpiece and irradiated (e.g., Refer to Patent Document 1), a type of laser beam that is transparent to the workpiece is placed inside the workpiece and irradiated with a converging point of a laser beam having a wavelength that is transparent to the workpiece, thereby forming a modified layer that becomes the starting point of division inside the workpiece. (e.g., see Patent Document 2), the converging point of a laser beam with a wavelength that is transparent to the workpiece is placed inside the workpiece and irradiated, so that it reaches from the surface of the workpiece to the back side, and the starting point of division is There is a type that forms a plurality of shield tunnels consisting of pores and an amorphous region surrounding the pores (for example, see Patent Document 3), and depending on the type of workpiece, processing precision, etc., a laser processing device is appropriate. is chosen accordingly.

Among the above-described laser processing devices, especially the type that performs ablation processing, debris (laser processing debris) generated when a laser beam is irradiated on the surface of the wafer scatters and adheres to the surface of the device formed on the wafer, Since there is a risk of deteriorating the quality of the device, before laser processing, the surface of the wafer is coated with a liquid resin that transmits the laser beam used for processing to prevent debris from adhering, and after laser processing, the wafer surface is coated with a liquid resin that transmits the laser beam used for processing. It has been proposed to remove the liquid resin (see, for example, Patent Document 4).

Patent Document 1: Japanese Patent Publication No. Heisei 10-305420 Patent Document 2: Japanese Patent No. 3408805 Patent Document 3: Japanese Patent Publication No. 2014-221483 Patent Document 4: Japanese Patent Publication No. 2004-188475

According to the technology described in Patent Document 4, by coating the device with liquid resin, debris can be prevented from adhering to the surface of the device, and processing quality is ensured. However, a process of applying the liquid resin and a process of removing the liquid resin after processing are required, causing a problem in productivity. Additionally, liquid resin has the problem of being uneconomical because it cannot be used repeatedly.

In addition, a technology has been proposed to prevent debris from adhering to the surface of the wafer by irradiating a laser beam while the wafer is submerged and causing the debris to float in water. However, when a laser beam is irradiated to the wafer while the wafer is submerged, fine bubbles are generated from the area of the wafer irradiated with the laser beam, and these bubbles hinder the progress of the laser beam, making it impossible to perform the desired processing. There is a problem that says it cannot be done.

The present invention has been made in consideration of the above facts, and its purpose is to provide a laser processing device that does not interfere with the irradiation of the laser beam to the workpiece when processing a plate-shaped workpiece by irradiating the laser beam. is to provide.

According to the present invention, there is provided a laser processing device, comprising: a chuck table for holding a plate-shaped workpiece; a laser beam irradiation unit including a concentrator for irradiating a laser beam to the workpiece held on the chuck table; the chuck table and the concentrator; It includes a processing transfer unit that relatively processes and transfers, and a liquid layer generator located immediately below the concentrator to generate a layer of liquid on the upper surface of the workpiece, wherein the liquid layer generator includes a laser irradiated by the concentrator. A case having a transparent plate that allows light to pass through, a ceiling wall including the transparent plate, and a side wall having a lower end that hangs down from the outside of the ceiling wall to form a gap between the transparent plate and the workpiece; and a liquid supply unit that supplies liquid to the internal space of the case to fill the internal space with liquid, and wherein the case is disposed with a liquid spray nozzle that sprays liquid toward the irradiation position of the laser beam irradiated to the workpiece. A laser processing device is provided.

Preferably, dispersing means for dispersing the laser beam emitted from the laser oscillator is disposed in the laser beam irradiation unit.

According to the present invention, a laser processing device is provided in which irradiation of a laser beam to a workpiece is not interrupted. In particular, when the present invention is applied to a laser processing device that performs ablation processing, debris generated during laser processing can be prevented from adhering to the device even without coating the surface of the wafer with liquid resin. Prevents the processing quality from deteriorating.

1 is a perspective view of a laser processing device according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view of a part of the laser processing device shown in FIG. 1.
FIG. 3 is a perspective view of (a) a liquid layer generator mounted on the laser processing device shown in FIG. 1 and (b) an exploded perspective view of the liquid layer generator.
FIG. 4 is a block diagram schematically illustrating the optical system of the laser beam irradiation unit mounted on the laser processing device shown in FIG. 1.
FIG. 5 is a partially enlarged cross-sectional view showing the operating state of the liquid layer generator mounted on the laser processing device shown in FIG. 1 during processing.

Hereinafter, a laser processing device according to an embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 shows a perspective view of the laser processing device 2 and a plate-shaped workpiece (for example, a wafer 10 made of silicon) processed by the laser processing device 2 according to an embodiment of the present invention. The laser processing device 2 is disposed on a base 21 and includes a holding means 22 for holding a plate-shaped workpiece, a moving mechanism 23 for moving the holding means 22, and a base 21. Frame 26 consisting of a vertical wall portion 261 erected in the Z direction indicated by an arrow Z on the side of the upper moving mechanism 23 and a horizontal wall portion 262 extending in the horizontal direction from the upper end of the vertical wall portion 261. ), a liquid supply mechanism 4, and a laser beam irradiation unit 8. As shown in the drawing, the wafer 10 is supported on the annular frame F through, for example, an adhesive tape T, and is held on the chuck table 34 of the holding means 22. In addition, the above-described laser processing device 2 is entirely covered with a housing, etc., which is omitted for convenience of explanation, and is configured to prevent dust, dust, etc. from entering the inside.

FIG. 2 shows the laser processing device 2 shown in FIG. 1 in a state in which the liquid recovery pool 60 constituting a part of the liquid supply mechanism 4 is removed from the laser processing device 2 and disassembled. It is a perspective view.

Referring to FIG. 2, the laser processing device 2 according to this embodiment will be described in detail.

Inside the horizontal wall portion 262 of the frame 26, an optical system constituting a laser beam irradiation unit 8 that irradiates a laser beam to the wafer 10 held by the holding means 22 is accommodated. A concentrator 86 constituting a part of the laser beam irradiation unit 8 is disposed on the lower surface side of the distal end of the horizontal wall portion 262, at a position adjacent to the concentrator 86 in the direction indicated by arrow X in the drawing. An alignment unit 88 is disposed. The alignment unit 88 is used to image the workpiece held by the holding means 22, detect the area where laser processing is to be performed, and align the processing position of the light concentrator 86 with the workpiece. do.

The alignment unit 88 includes an imaging device (CCD) that uses visible light to image the surface of the wafer 10. Depending on the material constituting the wafer 10, an infrared irradiation means for irradiating infrared rays, an optical system for capturing infrared rays irradiated by the infrared irradiation means, and an imaging device for outputting an electric signal corresponding to the infrared rays captured by the optical system. It is preferable to include a device (infrared CCD).

The holding means 22 includes a rectangular X-axis direction movable plate 30 mounted on the base 21 so as to be movable in the X-axis direction indicated by arrow ), a rectangular Y-axis direction movable plate 31 mounted on the It includes a support 32 and a rectangular cover plate 33 fixed to the top of the support 32. A chuck table 34 extending upward through a long hole formed on the cover plate 33 is disposed on the cover plate 33. The chuck table 34 is configured to hold a circular workpiece and to be rotatable by rotation drive means (not shown). On the upper surface of the chuck table 34, a circular adsorption chuck 35 is formed of a porous material and extends substantially horizontally. The suction chuck 35 is connected to a suction means (not shown) by a passage passing through the support post 32, and four clamps 36 are evenly arranged around the suction chuck 35. The clamp 36 holds the frame F holding the wafer 10 when fixing the wafer 10 to the chuck table 34 . The X-axis direction is a direction indicated by an arrow (X) in FIG. 2, and the Y-axis direction is a direction indicated by an arrow (Y) and is a direction orthogonal to the The plane defined by the X-axis direction and the Y-axis direction is substantially horizontal.

The movement mechanism 23 includes an X-axis direction movement mechanism 50 and a Y-axis direction movement mechanism 52. The X-axis direction movement mechanism 50 converts the rotational motion of the motor 50a into linear motion through the ball screw 50b and transmits it to the The X-axis direction movable plate 30 is advanced and retreated in the X-axis direction along (27, 27). The Y-axis direction movement mechanism 52 converts the rotational motion of the motor 52a into linear motion through the ball screw 52b and transmits it to the Y-axis direction movable plate 31, 30) The Y-axis direction movable plate 31 is advanced and retreated in the Y-axis direction along the upper guide rails 37, 37. In addition, although not shown, position detection means are arranged in the X-axis direction movement mechanism 50 and the Y-axis direction movement mechanism 52, respectively, to determine the position of the chuck table 34 in the The position and rotational position in the circumferential direction are accurately detected, and the 34) can be positioned accurately. The above-described Shiki becomes a means of indexing transport.

Referring to FIGS. 1 to 3, the liquid supply mechanism 4 will be described. As shown in FIG. 1, the liquid supply mechanism 4 includes a liquid layer generator 40, a liquid supply pump 44, a filtration filter 45, a liquid recovery pool 60, and a liquid layer generator ( 40) and a pipe 46a connecting the liquid supply pump 44, and a pipe 46b connecting the liquid recovery pool 60 and the filtration filter 45. Additionally, it is preferable that the pipes 46a and 46b are partially or entirely formed of flexible hoses.

The liquid layer generator 40 is located immediately below the concentrator 86, as shown in (a) of FIG. 3, and more specifically, is attached to the lower end of the concentrator 86. An exploded view of the liquid layer generator 40 is shown in (b) of FIG. 3. As can be understood from (b) in FIG. 3 , the liquid layer generator 40 is composed of a case 42 and a liquid supply unit 43.

The case 42 has a substantially rectangular shape in plan view and is composed of a ceiling wall 421 and a side wall 422. The ceiling wall 421 has a substantially square shape in plan view, and a circular opening 421a is formed in the central portion into which the lower end of the concentrator 86 is inserted and fixed. A transparent plate 423 is disposed at the bottom of the circular opening 421a to allow passage of the laser beam LB, which will be described later, and closes the bottom of the circular opening 421a. That is, the ceiling wall 421 includes a transparent plate 423. In the ceiling wall 421, air bleed holes 421b penetrating in the vertical direction (X-axis direction) are arranged in four parts so as to surround the circular opening 421a. The transparent plate 423 is formed of transparent glass, but is not limited to this, and may be, for example, a transparent plate made of resin such as acrylic.

The side wall 422 is a member that hangs down from the outside of the ceiling wall 421 and is formed to cover the side surface of the internal space 42a formed by the case 42. As shown in (b) of FIG. 3, the side wall 422 includes two first frame members 422b and 422b that oppose each other in the X-axis direction and extend in the Y-axis direction, and extend in the A second frame member 422c constituting the side wall to which the supply unit 43 is connected, a third frame member 422d extending in the X-axis direction opposite to the second frame member 422c, and a second frame member ( It is configured by a liquid spray nozzle 422e formed at 422c).

Liquid inlet ports 422g and 422g are formed on the side of the second frame member 422c to which the liquid supply portion 43 is connected. Liquid passages 422h and 422h extending in the Y-axis direction are formed inside the first frame members 422b and 422b and are connected to the liquid introduction ports 422g and 422g. Additionally, a liquid supply port 422i opening toward the internal space 422a is formed on the inner side surfaces of the two first frame members 422b, and the liquid supply port 422i is connected to the liquid passage 422h. do. That is, the liquid introduction port 422g communicates with the internal space 422a through the liquid passage 422h and the liquid supply port 422i.

The liquid spray nozzle 422e is formed at the center of the second frame member 422c. A spray nozzle inlet 422f is formed on the upper surface of the second frame member 422c, and the spray nozzle inlet 422f communicates with the internal space 422a through a liquid spray nozzle 422e. The passage formed by the injection nozzle 422e is formed toward the lower part of the internal space 422a so that the passage cross-sectional area gradually narrows. The operation of this liquid jet nozzle 422e will be explained in detail later.

The liquid supply unit 43 includes a supply port 43a for introducing liquid into the interior, an internal passage 43b formed inside, a central discharge port 43c communicating through the internal passage 43b, and a sub-discharge port ( 43d, 43d). As shown in FIG. 3(b), when connecting the liquid supply unit 43 to the case 42, the central outlet 43c is connected to the injection nozzle inlet 422f, and the sub outlet 43d is connected to the liquid. It is connected to the inlet (422g).

The liquid layer generator 40 includes the configuration described above, and the supply port 43a of the liquid supply unit 43 includes an internal passage 43b, a central outlet 43c, a sub-discharge port 43d, and a liquid It communicates with the internal space 422a of the case 42 through the injection nozzle 422e and the liquid passage 422h.

Returning to Figures 1 and 2, the liquid recovery pool 60 will be described. As shown in FIG. 2, the liquid recovery pool 60 includes an external frame 61 and two waterproof covers 66.

The external frame 61 includes an outer wall 62a extending in the X-axis direction indicated by an arrow And inner walls 63a, 63b arranged in parallel at a predetermined interval on the inside of 62b), and a bottom wall 64 connecting the lower ends of the outer walls 62a, 62b and the inner walls 63a, 63b. do. The outer walls 62a, 62b, the inner walls 63a, 63b, and the bottom wall 64 form a rectangular liquid recovery passage 70 with a longitudinal direction along the X-axis direction and a width direction along the Y-axis direction. do. Openings penetrating upward and downward are formed inside the inner walls 63a and 63b constituting the liquid recovery path 70. The bottom wall 64 constituting the liquid recovery passage 70 is provided with a slight slope in the A liquid discharge hole 65 is disposed at the corner portion of . A pipe 46b is connected to the liquid discharge hole 65, and is connected to the filtration filter 45 through the pipe 46b. Additionally, the outer frame 61 is preferably formed of a stainless steel plate that is resistant to corrosion and rust.

The two waterproof covers 66 include a door-shaped fixing member 66a and a corrugated box-shaped resin cover member 66b fixed to both ends of the fixing tool 66a. The fixing bracket 66a is formed to a size that can span the two inner walls 63a of the outer frame 61 that are arranged to face each other in the Y-axis direction. One side of the fixing brackets 66a of the two waterproof covers 66 is respectively fixed to the inner wall 63b of the outer frame 61 arranged to face each other in the X-axis direction. The liquid recovery pool 60 constructed in this way is fixed on the base 21 of the laser processing device 2 by a fixture not shown. The cover plate 33 of the holding means 22 is attached by sandwiching the fixing brackets 66a of the two waterproof covers 66 with each other. In addition, the end surface of the cover plate 33 in the ) in the Y-axis direction. Accordingly, the cover plate 33 is attached to the waterproof cover 66 after installing the outer frame 61 of the liquid recovery pool 60 on the base 21. According to the above configuration, when the cover plate 33 is moved in the X-axis direction by the move In addition, the method of attaching the waterproof cover 66 and the cover plate 33 is not limited to the above-described sequence, and for example, two waterproof covers 66 may be attached to the inner wall 63b of the external frame 61. Before this, the cover plate 33 may be attached in advance, and the waterproof cover 66 may be attached together with the cover plate 33 to the external frame 61 previously attached to the base 21.

Returning to FIG. 1 and continuing the explanation, the liquid supply mechanism 4 includes the above-described configuration, so that the liquid W discharged from the discharge port 44a of the liquid supply pump 44 flows into the pipe 46a. ) is supplied to the liquid layer generator 40. The liquid W supplied to the liquid layer generator 40 is sprayed toward the internal space 422a from the liquid spray nozzle 422e and the liquid supply port 422i of the case 42 of the liquid layer generator 40. . The liquid W sprayed from the liquid layer generator 40 flows on the cover plate 33 or the waterproof cover 66 and flows into the liquid recovery pool 60. The liquid W flowing into the liquid recovery pool 60 flows through the liquid recovery passage 70 and is collected in the liquid discharge hole 65 provided at the lowest position of the liquid recovery passage 70. The liquid W collected in the liquid discharge hole 65 is guided to the filtration filter 45 via the pipe 46b, and the laser processing debris, garbage, dust, etc. are removed from the filtration filter 45. It is removed and returned to the liquid supply pump 44. In this way, the liquid W discharged by the liquid supply pump 44 circulates within the liquid supply mechanism 4.

FIG. 4 is a block diagram schematically showing the optical system of the laser beam irradiation unit 8. As shown in FIG. 4, the laser beam irradiation unit 8 includes a laser oscillator 82 that oscillates a pulsed laser, and an attenuator that adjusts the output of the laser beam LB emitted from the laser oscillator 82. (not shown), a reflection mirror (not shown) that appropriately changes the optical path of the laser beam LB emitted from the laser oscillator 82, and a dispersion mirror that disperses the irradiation direction of the laser beam LB. It includes a polygon mirror 91 as a means and a concentrator 86. The laser oscillator 82 oscillates a laser of a wavelength that has absorption properties for, for example, a workpiece.

The polygon mirror 91 disposed above the condenser 86 includes a motor (not shown) that rotates the polygon mirror 91 at high speed in the direction indicated by the arrow R. Inside the concentrator 86, a converging lens (fθ lens) 86a is disposed to converge the laser beam LB and irradiate it to the workpiece. As shown in the figure, the polygon mirror 91 has a plurality of mirrors M arranged concentrically with respect to the rotation axis of the polygon mirror 91. The fθ lens 86a is located below the polygon mirror 91, and focuses the laser beam LB reflected by the polygon mirror 91 and radiates it to the wafer 10 on the chuck table 34. . As the polygon mirror 91 rotates, the angle of the laser beam LB reflected by the mirror M changes in a predetermined range, so that the laser beam LB moves in the processing transfer direction (X axis) on the wafer 10. The radiation is dispersed and irradiated in a predetermined range (direction).

Additionally, the laser beam irradiation unit 8 includes converging point position adjustment means, not shown. Although the specific configuration of the converging point position adjustment means is omitted, for example, a ball screw with a nut fixed to the concentrator 86 and extending in the Z direction indicated by arrow Z, and a motor connected to one end of the ball screw are used. It is good to have a configuration. With this configuration, the rotational motion of the motor is converted into linear motion, and the concentrator 86 is moved along a guide rail (not shown) disposed in the Z direction, thereby causing the laser to be focused by the concentrator 86. Adjust the position of the condensing point of the light LB in the Z direction.

The laser processing device 2 of the present invention includes substantially the same configuration as described above, and its operation will be described below.

In carrying out laser processing by the laser processing device 2 of the present embodiment, a plate-shaped workpiece supported on the annular frame F through an adhesive tape T, for example, silicon (silicon with a device formed on the surface) A wafer 10 made of Si) is prepared. Once the wafer 10 has been prepared, the wafer 10 is placed on the suction chuck 35 of the chuck table 34 shown in FIG. 1 with the surface on which the device is formed facing upward, and fixed with a clamp 36 or the like. When the wafer 10 is fixed on the suction chuck 35, a suction source (not shown) is activated to generate a suction force on the suction chuck 35 to adsorb and hold the wafer 10.

If the wafer 10 is held in the suction chuck 35, the chuck table 34 is appropriately moved in the is placed directly below the alignment unit (88). If the wafer 10 is placed directly below the alignment unit 88, an image of the wafer 10 is captured by the alignment unit 88. Subsequently, based on the image of the wafer 10 captured by the alignment unit 88, the positions of the wafer 10 and the concentrator 86 are aligned using a method such as pattern matching. Based on the positional information obtained through this alignment, the chuck table 34 is moved to position the concentrator 86 above the processing start position on the wafer 10. Subsequently, the concentrator 86 is moved in the Z direction by means of converging point position adjustment means (not shown) to the surface height of one end of the wafer 10 at the division line, which is the irradiation start position of the laser beam LB. Position the light-concentrating point.

Figure 5 shows a partially enlarged cross-sectional view cut in the Y-axis direction of the liquid layer generator 40. As understood from FIG. 5, the liquid layer generator 40 is disposed at the lower end of the concentrator 86, and when the condensing point is located at the surface height of the wafer 10, the liquid layer generator 40 is configured. It is set so that a slight gap of about 0.5 mm to 2.0 mm is formed between the lower end of the side wall 422 constituting the liquid supply part 43 and the case 42 and the surface of the wafer 10.

If the position of the concentrator 86 and the wafer 10 has been aligned, the necessary and sufficient liquid W is replenished to the liquid supply mechanism 4 through the liquid recovery passage 70 of the liquid recovery pool 60, Operate the liquid supply pump (44). As the liquid W circulating in the liquid supply mechanism 4, pure water is used, for example.

The liquid supply mechanism 4 includes the above-described configuration, so that the liquid W discharged from the discharge port 44a of the liquid supply pump 44 passes through the pipe 46a to the liquid layer generator 40. ) is supplied to. As shown in FIG. 5, the liquid W supplied to the liquid layer generator 40 flows into the internal space ( 422). Additionally, the liquid W is sprayed from the tip of the liquid spray nozzle 422e into the internal space 422a. The gap formed between the lower end of the side wall 422 of the case 42 and the wafer 10 is smaller than the passage cross-sectional area of the liquid passage 422h and the liquid spray nozzle 422e. Then, the air existing in the internal space 422a is gradually discharged from the air bleed hole 421b formed in the ceiling wall 421, so that the internal space 422a is gradually filled with the liquid W. The liquid W discharged from the gap between the lower end of the side wall 422 of the case 42 and the wafer 10 and the air bleed hole 421b then flows down and is recovered in the liquid recovery pool 60. The liquid W flowing down from the liquid recovery pool 60 flows through the liquid recovery passage 70 and collects in the liquid discharge hole 65 provided at the lowest position of the liquid recovery passage 70. The liquid W accumulated in the liquid discharge hole 65 is guided to the filtration filter 45 via the pipe 46b, is purified in the filtration filter 45, and is returned to the liquid supply pump 44. In this way, the liquid W discharged by the liquid supply pump 44 circulates within the liquid supply mechanism 4.

The liquid supply mechanism 4 starts to operate, and as a predetermined time (approximately several minutes) elapses, the air in the internal space 422a of the case 42 is completely discharged and filled with the liquid W. The layer is formed and circulates stably.

With the liquid W stably circulating in the liquid supply mechanism 4, the chuck table 34 is processed by operating the X-axis direction movement mechanism 50 while operating the laser beam irradiation unit 8. It is moved at a predetermined moving speed in the transfer direction (X-axis direction). The laser beam LB emitted from the condenser 86 passes through the transparent plate 423 of the liquid layer generator 40 and the layer of liquid W filling the internal space 422a to process the wafer 10. The location (scheduled division line) is investigated. When irradiating the laser beam LB to the wafer 10, as explained based on FIG. 4, according to the rotation of the polygon mirror 91, the laser beam is emitted in the X-axis direction, which is the processing transfer direction, with respect to the wafer 10. (LB) is dispersed and investigated. After the laser beam LB is irradiated to the predetermined mirror M, the laser beam LB is irradiated to the next mirror M located downstream in the rotation direction R of the polygon mirror 91. Thus, the laser beam LB is continuously irradiated to the wafer 10 in a dispersed manner. While the laser beam LB is emitted from the laser oscillator 82 and the polygon mirror 91 is rotating, this laser processing is repeated. In addition, the number of mirrors M constituting the polygon mirror 91, the rotation speed of the polygon mirror 91, etc. are appropriately determined depending on the workpiece.

In addition, the laser processing conditions in the above-described laser processing device 2 can be implemented, for example, under the following processing conditions.

Wavelength of laser beam: 226 ㎚, 355 ㎚, 532 ㎚, 1064 ㎚

Average power: 10∼100 W

Repetition frequency: 0∼300 MHz

Pulse width: 50 fs∼1 ㎱

Processing feed speed: 10∼1000 mm/s

When ablation processing is performed in the above-mentioned state, bubbles are generated in the liquid W at the position of the wafer 10 where the laser beam LB is irradiated. In contrast, in the present embodiment, as shown in FIG. 5, the liquid W always flows with respect to the internal space 422a of the liquid layer generator 40 formed on the wafer 10, and the irradiation position of the laser beam The liquid W is sprayed from the liquid spray nozzle 422e toward . Accordingly, air bubbles generated near the irradiation position of the laser beam LB are quickly discharged to the outside of the case 42 from the laser beam irradiation position on the wafer 10 and are removed. In particular, according to this embodiment, the liquid spray nozzle 422e formed in the case 42 sprays the liquid W from a direction orthogonal to the X-axis direction, that is, the Y-axis direction, which is the direction in which the laser beam LB is dispersed. Spray. Accordingly, the laser beam LB can be irradiated to the wafer 10 while avoiding air bubbles generated by ablation processing, and satisfactory ablation processing can be continuously performed.

In addition, by continuously spraying the liquid W to the irradiation position of the laser beam LB on the wafer 10, the debris released in the liquid W is quickly removed from the wafer 10 along with the air bubbles. . As understood from FIG. 1, the liquid W containing the above-described bubbles and debris flows over the cover plate 33 and the waterproof cover 66, and flows into the liquid recovery passage 70 of the liquid recovery pool 60. ) is derived. The liquid W introduced into the liquid recovery passage 70 flows while releasing the bubbles generated by the ablation process to the outside, and is discharged from the liquid discharge hole 65 formed at the bottom of the liquid recovery passage 70. . The liquid W discharged from the liquid discharge hole 65 is guided to the filtration filter 45 through the pipe 46b and supplied again to the liquid supply pump 44. In this way, as the liquid W circulates through the liquid supply mechanism 4, debris, waste, etc. are appropriately captured by the filtration filter 45, and the liquid W is maintained in a clean state.

If the above-mentioned ablation processing is performed on a predetermined division line extending in the first direction, by operating the moving mechanism 23, an unprocessed division line is adjacent in the Y-axis direction to the division line on which laser processing has already been performed. A concentrator 86 is placed on one end of and laser processing similar to the ablation processing described above is performed. Then, if ablation processing has been performed on all the division lines extending in the first direction, the chuck table 34 is rotated 90 degrees to extend the division lines in the first direction orthogonal to the previously processed division lines in the second direction. The same ablation process is performed on the unprocessed division scheduled line. In this way, ablation processing can be performed on all the division lines on the wafer 10.

According to this embodiment, laser processing is performed by irradiating the laser beam LB to the wafer 10 through the transparent plate 423 and the layer of liquid W disposed in the liquid layer generator 40, and the wafer ( 10) Air bubbles generated from the surface and debris generated by laser processing are quickly removed along with the liquid W. As a result, air bubbles generated from the surface of the wafer 10 do not interfere with laser processing, and debris is prevented from adhering to the device after processing, thereby preventing processing quality from deteriorating.

In the above-described embodiment, the laser beam LB emitted from the laser oscillator 82 is dispersed by the polygon mirror 91 and guided to the converging lens 86. However, the present invention is not limited to this, and the polygon mirror 91 ) Instead, it may be a mirror whose reflection direction is fixed. In addition, in the above-described embodiment, the laser processing performed on the wafer 10 is an ablation processing, but processing to form a modified layer inside the workpiece (e.g., the single processing described in Patent Document 2), It does not prevent application to processing to form a so-called shield tunnel (for example, laser processing described in Patent Document 3).

2: Laser processing device
4: Liquid supply mechanism
8: Laser beam irradiation unit
10: Wafer (plate-shaped workpiece)
21: base
22: means of maintenance
23: Movement mechanism
26: frame
261: vertical wall
262: horizontal wall
30: X direction movable plate
31: Y direction movable plate
33: Cover plate
34: Chuck table
35: suction chuck
40: Liquid layer generator
42: case
421: Ceiling wall
421a: circular opening
421b: air vent hole
422: side wall
422a: interior space
422b: first frame member
422c: second frame member
422d: third frame member
422e: Liquid spray nozzle
422f: spray nozzle supply hole
422g: Liquid inlet
422h: liquid passage
422i: Liquid supply port
423: Transparent plate
43: Liquid supply part
43a: supply port
43b: internal passage
43c: central outlet
43d: secondary outlet
44: Liquid supply pump
45: Filtration filter
50: X direction movement mechanism
52: Y direction movement mechanism
60: Liquid recovery pool
60A: space part
65: liquid discharge hole
66: Corrugated box cover
70: Liquid recovery furnace
86: Concentrator
88: Alignment unit

Claims (2)

As a laser processing device,
A chuck table for holding a plate-shaped workpiece,
a laser beam irradiation unit including a concentrator that irradiates laser beam to the workpiece held on the chuck table;
a processing transfer unit that relatively processes and transfers the chuck table and the concentrator;
A liquid layer generator located immediately below the concentrator to generate a liquid layer on the upper surface of the workpiece,
The liquid layer generator,
a transparent plate that allows passage of the laser beam emitted by the concentrator;
A case having a ceiling wall including the transparent plate, and a side wall having a lower end that hangs down from the outside of the ceiling wall and forms a gap between the workpiece and the workpiece;
a liquid supply unit that supplies liquid to the internal space of the case and fills the internal space with liquid;
In the internal space of the case, a liquid spray nozzle is disposed for spraying the liquid introduced from the liquid supply unit into the internal space toward the irradiation position of the laser beam irradiated to the workpiece,
The liquid injection nozzle is a laser processing device that sprays liquid in a direction perpendicular to the processing transfer direction. The laser processing device according to claim 1, wherein dispersing means for dispersing the laser beam emitted from the laser oscillator is disposed in the laser beam irradiation unit.

Images