JP2017051985A - Laser processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processing apparatus that facilitates modification of the energy distribution of a laser beam.SOLUTION: A laser processing apparatus 1 includes: a chuck table 10 for holding a workpiece W; and laser beam emitting means 20 for irradiating the workpiece W held by the chuck table 10 with a pulsed laser beam LB, and performing processing. The laser beam emitting means 20 includes: a laser beam oscillator 21 for emitting the pulsed laser beam LB; a digital mirror device 22 for adjusting the energy distribution of the emitted pulsed laser beam LB; a collection lens 23 for collecting the pulsed laser beam LB entering via the digital mirror device 22; and control means 100 for controlling the digital mirror device 22. The digital mirror device 22 adjusts the energy distribution by pruning desired portions of the pulsed laser beam LB.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a laser processing apparatus.

  The laser processing apparatus uses an attenuator (consisting of a λ / 2 wavelength plate, a beam splitter, and a beam damper) to make a laser beam oscillated from a laser beam oscillator have a desired power (see, for example, Patent Document 1). In addition, laser processing apparatuses that ablate the workpiece are also used (see, for example, Patent Document 2 and Patent Document 3).

JP 2013-229403 A JP 2012-156168 A JP 2008-073711 A

  The laser processing apparatus disclosed in Patent Document 1 requires a motor that rotates a λ / 2 wavelength plate in the attenuator, takes time for mechanical control, and cannot change the power in a very short time. was there.

  In the laser processing apparatus disclosed in Patent Document 2, the energy distribution of the laser beam is important. For example, in the laser processing apparatus disclosed in Patent Document 3, a laser beam having a Gaussian distribution is changed to a top hat distribution using an aspheric lens. However, in such a configuration, there is no degree of freedom such as arbitrarily changing to a Gaussian distribution and a top hat distribution.

  This invention is made | formed in view of such a point, and it aims at providing the laser processing apparatus which can change the energy distribution of a laser beam easily.

  In order to solve the above-described problems and achieve the object, the laser processing apparatus of the present invention includes a chuck table for holding a workpiece, and processing by irradiating the workpiece held on the chuck table with a pulsed laser beam. A laser beam irradiating means, the laser beam irradiating means comprising: a laser beam oscillator for oscillating a pulse laser beam; a digital mirror device for adjusting an energy distribution of the oscillated pulse laser beam; and the digital mirror device. And a control means for controlling the digital mirror device, wherein the digital mirror device thins out a desired portion of the pulse laser beam to reduce the energy of the pulse laser beam. Characterized by adjusting the distribution

  Using the digital mirror device, it is desirable to adjust the energy distribution of the pulsed laser beam applied to the workpiece to a Gaussian distribution or a top hat distribution.

  It is desirable that a beam expander is set between the laser beam oscillator and the digital mirror device.

  Therefore, in the laser processing apparatus of the present invention, since a desired portion of the pulse laser beam can be thinned out by the digital mirror device, the energy distribution of the pulse laser beam can be easily changed.

FIG. 1 is a perspective view illustrating a schematic configuration example of the laser processing apparatus according to the first embodiment. FIG. 2 is a diagram showing a schematic configuration example of the laser beam irradiation means of the laser processing apparatus shown in FIG. FIG. 3 is a diagram showing a main part where the laser beam application means shown in FIG. 2 irradiates a laser beam. FIG. 4 is a diagram showing an ideal energy distribution of the pulsed laser beam stored by the control means of the laser processing apparatus shown in FIG. FIG. 5 is a diagram showing a positional relationship between the digital mirror device of the laser processing apparatus shown in FIG. 1 and the spot of the pulse laser beam. FIG. 6 is a diagram showing the energy distribution of the pulsed laser beam measured by the output measuring means before adjustment of the laser processing apparatus according to the first embodiment. FIG. 7 is a diagram showing the energy distribution of the pulsed laser beam along the line AA in FIG. FIG. 8 is an enlarged view showing a VIII portion in FIG. FIG. 9 is a diagram showing an ideal energy distribution of the pulsed laser beam stored by the control unit of the laser processing apparatus according to the second embodiment. FIG. 10 is a diagram showing an example of the energy distribution of the pulse laser beam irradiated by the laser beam irradiation means of the laser processing apparatus shown in FIG. FIG. 11 is a diagram showing the positional relationship between the digital mirror device after adjustment of the laser processing apparatus shown in FIG. 9 and the spot of the pulse laser beam. 12 is a diagram showing an example of the energy distribution of the pulse laser beam shown in FIG. FIG. 13 is a diagram illustrating an ideal energy distribution of the pulsed laser beam stored by the control unit of the laser processing apparatus according to the first modification of the first and second embodiments. FIG. 14 is a diagram illustrating an ideal energy distribution of the pulsed laser beam stored by the control unit of the laser processing apparatus according to the first embodiment and the second modification of the second embodiment. FIG. 15 is a diagram illustrating a schematic configuration example of a laser beam irradiation unit of a laser processing apparatus according to Modification 3 of Embodiment 1 and Embodiment 2.

  Embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

Embodiment 1
A laser processing apparatus according to Embodiment 1 will be described with reference to the drawings. FIG. 1 is a perspective view illustrating a schematic configuration example of the laser processing apparatus according to the first embodiment, and FIG. 2 is a diagram illustrating a schematic configuration example of a laser beam irradiation unit of the laser processing apparatus illustrated in FIG. 3 is a diagram showing the main part of the laser beam irradiation means shown in FIG. 2 that irradiates the laser beam, and FIG. 4 shows the pulse laser beam stored by the control means of the laser processing apparatus shown in FIG. FIG. 5 is a diagram illustrating an ideal energy distribution, and FIG. 5 is a diagram illustrating a positional relationship between the digital mirror device of the laser processing apparatus illustrated in FIG. 1 and the spot of the pulse laser beam.

  The laser processing apparatus 1 irradiates the workpiece W with a pulsed laser beam LB (shown in FIG. 2) along the planned division line L of the workpiece W to perform ablation processing. In the first embodiment, the workpiece W to be ablated by the laser processing apparatus 1 is a disk-shaped semiconductor wafer or optical device wafer whose base material is silicon, sapphire, gallium or the like, as shown in FIG. It is. In the workpiece W, a device D is formed in an area partitioned by a plurality of division lines L formed in a lattice pattern on the surface WS.

  The workpiece W has a functional layer that forms an insulating film and a circuit laminated on the surface. In the first embodiment, the insulating film forming the functional layer is a low dielectric composed of an SiO 2 film, an inorganic film such as SiOF or BSG (SiOB), or an organic film such as a polymer film such as polyimide or parylene. It consists of a rate insulator film (Low-k film).

  The workpiece W is formed by attaching the adhesive tape T to the back surface WR on the back side of the front surface WS on which a plurality of devices D are formed, and attaching the outer edge of the adhesive tape T to the annular frame F. Is supported by an adhesive tape T. In the first embodiment, the workpiece W is irradiated with a pulsed laser beam LB (shown in FIG. 2) along the planned division line L in a state where the workpiece W is supported by the opening of the annular frame F with the adhesive tape T, and ablation processing is performed. Is given. The workpiece W is divided into individual devices D by ablation processing or the like.

  As shown in FIG. 1, the laser processing apparatus 1 includes a chuck table 10 that holds a workpiece W, and laser beam irradiation means that irradiates the workpiece W held on the chuck table 10 with a pulsed laser beam LB to perform laser processing. 20, an X-axis moving unit 30 that relatively moves the chuck table 10 and the laser beam irradiation unit 20 in the X-axis direction, and a Y-axis moving unit 40 that relatively moves the chuck table 10 and the laser beam irradiation unit 20 in the Y-axis direction. The image pickup means 50, the output measurement means 70, and the control means 100 are provided.

  The chuck table 10 holds the workpiece W on which the workpiece W before processing is placed on the holding surface 10a and is adhered to the opening of the annular frame F via the adhesive tape T. The chuck table 10 has a disk shape in which a portion constituting the holding surface 10a is formed of porous ceramic or the like, and is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown) and placed on the holding surface 10a. The workpiece W is held by being sucked through the adhesive tape T. Around the chuck table 10, there are provided a plurality of clamp portions 11 that are driven by an air actuator and sandwich the annular frame F around the workpiece W.

  The X-axis moving unit 30 is a processing feed unit that moves the chuck table 10 in the X-axis direction to process and feed the chuck table 10 in the X-axis direction parallel to both the width direction and the horizontal direction of the apparatus main body 2. is there. The Y-axis moving means 40 is an index feeding means for indexing and feeding the chuck table 10 by moving the chuck table 10 in the Y-axis direction parallel to the horizontal direction and perpendicular to the X-axis direction. The X-axis moving means 30 and the Y-axis moving means 40 are known ball screws 31 and 41 that are rotatably provided around the axis, and known pulse motors 32 and 42 that rotate the ball screws 31 and 41 around the axis. In addition, known guide rails 33 and 43 that support the chuck table 10 so as to be movable in the X-axis direction or the Y-axis direction are provided. In addition, the laser processing apparatus 1 includes a rotational drive source 60 that rotates the chuck table 10 around a central axis parallel to the Z-axis direction orthogonal to both the X-axis direction and the Y-axis direction. The rotational drive source 60 is disposed on the moving table 12 that is moved in the X-axis direction by the X-axis moving means 30.

  The image pickup means 50 picks up an image of the workpiece W held on the chuck table 10 and is arranged at a position parallel to the laser beam irradiation means 20 in the X-axis direction. In the first embodiment, the imaging unit 50 is attached to the tip of the support column 4. The imaging means 50 is configured by a CCD camera that images the workpiece W held on the chuck table 10.

  The laser beam irradiation means 20 irradiates the workpiece W with the pulse laser beam LB on the surface of the workpiece W held on the holding surface 10a of the chuck table 10 to ablate the workpiece W (corresponding to processing). The pulsed laser beam LB is a laser beam having a wavelength (for example, 355 nm) that is absorptive with respect to the workpiece W. The laser beam irradiating means 20 is attached to the tip of the support column 4 connected to the wall portion 3 erected from the apparatus main body 2 of the laser processing apparatus 1.

  As shown in FIG. 2, the laser beam irradiation means 20 includes a laser beam oscillator 21 that oscillates the pulse laser beam LB, a digital mirror device 22 that adjusts the energy distribution ED (shown in FIG. 7) of the oscillated pulse laser beam LB, The optical lens 23, the beam damper 24, and the control means 100 are provided.

  The laser beam oscillator 21 oscillates a pulsed laser beam LB having a circular spot shape orthogonal to the optical axis. The pulse laser beam LB oscillated by the laser beam oscillator 21 is parallel light. The laser beam oscillator 21 irradiates the oscillated pulse laser beam LB toward the digital mirror device 22. The laser beam oscillator 21 appropriately adjusts the frequency of the oscillating pulsed laser beam LB in accordance with the type of workpiece W, the processing form, and the like. As the laser beam oscillator 21, for example, a YAG laser beam oscillator or a YVO laser beam oscillator can be used.

  The digital mirror device 22 includes a large number of mirrors 25 (shown in FIG. 5) having a size of about a dozen μm arranged in two directions orthogonal to each other, and a C-MOS (Complementary MOS) capable of changing the direction of each mirror 25. And a driving mechanism including a complementary MOS). In the first embodiment, the digital mirror device 22 includes about 1 million mirrors 25, but is not limited thereto. As shown in FIG. 5, the mirror 25 of the digital mirror device 22 is irradiated with the entire pulse laser beam LB oscillated by the laser beam oscillator 21. In the first embodiment, the plurality of mirrors 25 are arranged on a square, but the present invention is not limited to this.

  The digital mirror device 22 is configured to irradiate the condensing lens 23 with a pulsed laser beam LB (shown by a solid line in FIGS. 2 and 3) reflected by the mirror 25 when the driving mechanism is turned on and off, and the mirror The state of irradiating the beam damper 24 with the pulse laser beam LB reflected by the beam 25 (indicated by a one-dot chain line in FIGS. 2 and 3) is switched. In the first embodiment, the drive mechanism is positioned to irradiate the condenser laser beam 23 with the pulse laser beam LB when turned on, and is positioned to irradiate the beam damper 24 with the pulse laser beam LB when turned off. It is not limited. The pulse laser beam LB reflected by the digital mirror device 22 is parallel light. That is, the shape and size of the spot of the pulse laser beam LB reflected by all the mirrors 25 of the digital mirror device 22 toward the condenser lens 23 or the beam damper 24 are the shape of the spot of the pulse laser beam LB oscillated by the laser beam oscillator 21, Equal to size.

  The condensing lens 23 condenses the pulse laser beam LB incident through the digital mirror device 22 on the workpiece W. In the first embodiment, the optical axis of the pulsed laser beam LB that is collected on the workpiece W by the condenser lens 23 is parallel to the Z-axis direction. The beam damper 24 shields the pulse laser beam LB reflected by each mirror 25 of the digital mirror device 22 without leaking outside. The beam damper 24 has such a size that all the driving mechanisms of the digital mirror device 22 are turned off and the pulse laser beam LB reflected by all the mirrors 25 can be shielded.

  The output measuring unit 70 measures an energy distribution (also referred to as a power distribution or an intensity distribution) in the spot of the pulsed laser beam LB irradiated from the condenser lens 23 of the laser beam irradiation unit 20. The output measuring means 70 is provided on the moving table 12 and is arranged next to the chuck table 10. The output measuring unit 70 measures the energy distribution of the pulse laser beam LB in a plane parallel to both the X-axis direction and the Y-axis direction of the pulse laser beam LB irradiated from the condenser lens 23 of the laser beam irradiation unit 20, and the measurement result Is output to the control means 100. As the output measuring means 70, a so-called thermal output measuring means using a thermocouple element, a so-called optical output measuring means using a photodiode, or a so-called energy output measuring means using a pyroelectric substance is used.

  The control unit 100 controls the above-described components to cause the laser processing apparatus 1 to perform a laser processing operation on the workpiece W. The control means 100 controls the digital mirror device 22, that is, switches on / off of each drive mechanism of the digital mirror device 22. The control means 100 stores an ideal energy distribution IE in the spot of the pulse laser beam LB irradiated on the workpiece W shown in FIG. 4 indicates the position from the center of the spot of the pulse laser beam LB in a plane parallel to both the X-axis direction and the Y-axis direction, and the vertical axis in FIG. 4 indicates the energy of the pulse laser beam LB. Yes. In the first embodiment, the ideal energy distribution IE of the pulse laser beam LB stored by the control unit 100 is a Gaussian distribution over the entire circumference. Before the laser processing of the workpiece W, the control unit 100 irradiates the output measuring unit 70 with the pulse laser beam LB from the laser beam irradiation unit 20, and the energy distribution of the pulse laser beam LB irradiated by the laser beam irradiation unit 20 is shown in FIG. The drive mechanisms of the digital mirror device 22 are switched on and off so that the ideal energy distribution IE shown is obtained.

  The control means 100 includes a computer system. The control means 100 includes an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a read only memory (ROM) or a random access memory (RAM), and an input / output interface device. And have.

  The arithmetic processing device of the control means 100 performs arithmetic processing according to a computer program stored in the storage device, and sends a control signal for controlling the laser processing device 1 via the input / output interface device to the laser processing device 1. To the above-described components. Further, the control means 100 is connected to a display means (not shown) constituted by a liquid crystal display device or the like that displays a processing operation state or an image, or an input means used when an operator registers processing content information or the like. . The input means includes at least one of a touch panel provided on the display means, a keyboard, and the like.

  Next, a process in which the laser processing apparatus 1 divides the workpiece W into individual devices D will be described with reference to the drawings. 6 is a diagram showing the energy distribution of the pulse laser beam measured by the output measuring means before the adjustment of the laser processing apparatus according to the first embodiment, and FIG. 7 shows the pulse laser beam along the AA line in FIG. FIG. 8 is a diagram showing an energy distribution, and FIG. 8 is an enlarged view showing a VIII portion in FIG. 6.

  First, the operator registers the processing content information in the control means 100 of the laser processing apparatus 1, and the operator places the back surface WR on the back side of the surface WS of the workpiece W on the holding surface 10 a of the chuck table 10. When there is an instruction to start the processing operation, the laser processing apparatus 1 starts the processing operation.

  In the processing operation, the control unit 100 drives the vacuum suction source to suck and hold the workpiece W on the chuck table 10. The control means 100 moves the chuck table 10 downward of the laser beam irradiation means 20 by the X-axis movement means 30 and the Y-axis movement means 40, and moves the output measurement means 70 provided on the movement table 12 to the laser beam irradiation means. It is positioned below the 20 condenser lenses 23. When the output measuring means 70 is positioned below the condenser lens 23 of the laser beam irradiation means 20, the control means 100 turns on all the drive mechanisms of the digital mirror device 22, and outputs the pulse laser beam LB from the laser beam irradiation means 20. Irradiate toward 70.

  The output measuring unit 70 outputs the measurement result to the control unit 100. For example, the control unit 100 compares the energy distribution ED of the pulse laser beam LB measured by the output measuring unit 70 shown in FIGS. 6 and 7 with the ideal energy distribution IE shown in FIG. 4 over the entire circumference. The control means 100 is a portion P (see FIGS. 6, 7 and 8) in which the difference between the energy distribution ED of the pulse laser beam LB measured by the output measuring means 70 and the ideal energy distribution IE shown in FIG. Extract). In the first embodiment, a portion P where the difference between the energy distribution ED of the pulse laser beam LB measured by the output measuring means 70 and the ideal energy distribution IE shown in FIG. 4 exceeds a predetermined value as a desired portion (see FIGS. 6 and 6). 7).

  The control unit 100 turns off a part of the drive mechanism of the digital mirror device 22 corresponding to the part P exceeding the predetermined value, and thins out part of the pulse laser beam LB of the part P exceeding the predetermined value. The control means 100 brings the energy distribution ED of the pulsed laser beam LB closer to (adjusts) the ideal energy distribution IE shown in FIG. Thus, the digital mirror device 22 of the laser processing apparatus 1 according to the first embodiment thins out the portion P in which the difference between the energy distributions ED and IE, which are the desired portions of the pulse laser beam LB, exceeds a predetermined value, and the energy distribution ED of the pulse laser beam LB. Adjust. In the first embodiment, the laser processing apparatus 1 uses the digital mirror device 22 to adjust the energy distribution ED of the pulse laser beam LB irradiated to the workpiece W to a Gaussian distribution over the entire circumference. In the first embodiment, the control unit 100 turns off every other driving mechanism of the digital mirror device 22 corresponding to the first region R1 on the outer peripheral side of the portion P exceeding the predetermined value, and The driving mechanism of the digital mirror device 22 corresponding to the region R2 of 2 is turned off at every third maximum, and a portion P in which the difference between the energy distributions ED and IE, which is a desired portion of the pulse laser beam LB, exceeds a predetermined value is thinned out.

  When the difference P between the energy distribution ED of the pulsed laser beam LB measured by the output measuring unit 70 and the ideal energy distribution IE shown in FIG. 4 does not exceed the predetermined value P, the control unit 100 removes from the laser beam irradiation unit 20. The irradiation of the pulsed laser beam LB is stopped, and the workpiece W held on the chuck table 10 is positioned below the imaging unit 50 by the X-axis moving unit 30 and the Y-axis moving unit 40, and the imaging unit 50 takes an image. The control unit 100 performs image processing such as pattern matching on the image captured by the imaging unit 50 and performs alignment for adjusting the relative position between the workpiece W held on the chuck table 10 and the laser beam irradiation unit 20. .

  The control unit 100 irradiates the pulsed laser beam LB from the laser beam irradiation unit 20 while the workpiece W and the laser beam irradiation unit held on the chuck table 10 by the X-axis movement unit 30, the Y-axis movement unit 40, and the rotation drive source 60. 20 is moved relative to each other, and the pulse laser beam LB is irradiated to all the division planned lines L one by one in order.

  Then, a part of the workpiece W is sublimated, and laser processing grooves are formed in the division lines L by ablation processing. When the control unit 100 irradiates all the scheduled division lines L with the pulsed laser beam LB, the control unit 100 moves the chuck table 10 away from the lower side of the laser beam irradiation unit 20 by the X-axis moving unit 30 and the Y-axis moving unit 40. The vacuum suction source is stopped at a position separated from the lower side of the laser beam irradiation means 20 to release the suction holding of the workpiece W. The operator removes the workpiece W subjected to laser processing from the chuck table 10 and places the next workpiece W before laser processing on the holding surface 10a of the chuck table 10 so that the workpiece is processed in the same manner as before. Laser processing of the workpiece W is performed.

  According to the laser processing apparatus 1 according to the first embodiment, the digital mirror device 22 can thin out a portion P in which the difference between the energy distributions ED and IE, which are desired portions of the pulse laser beam LB, exceeds a predetermined value. The energy distribution ED of the LB can be easily controlled to an arbitrary distribution at high speed, and the energy distribution ED of the pulse laser beam LB can be adjusted more easily and faster than using an attenuator. Therefore, the laser processing apparatus 1 according to the first embodiment can easily change the energy distribution ED of the pulse laser beam LB. Moreover, since the laser processing apparatus 1 can adjust the energy distribution ED of the pulse laser beam LB to an arbitrary distribution, in the first embodiment, it can be controlled to a Gaussian distribution. Furthermore, since the laser processing apparatus 1 adjusts the energy distribution ED of the pulse laser beam LB by the digital mirror device 22 that electrically switches, the energy distribution ED of the pulse laser beam LB can be quickly controlled, and the energy distribution ED. Can be arbitrarily adjusted partially.

[Embodiment 2]
A laser processing apparatus according to Embodiment 2 will be described with reference to the drawings. FIG. 9 is a diagram showing an ideal energy distribution of the pulsed laser beam stored by the control unit of the laser processing apparatus according to the second embodiment, and FIG. 10 is irradiated by the laser beam irradiation unit of the laser processing apparatus shown in FIG. 11 is a diagram illustrating an example of the energy distribution of the pulse laser beam to be performed, and FIG. 11 is a diagram illustrating the positional relationship between the digital mirror device after adjustment of the laser processing apparatus illustrated in FIG. 9 and the spot of the pulse laser beam. 12 is a diagram showing an example of the energy distribution of the pulse laser beam shown in FIG. 9 to 12, the same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  As shown in FIG. 9, the ideal energy distribution IE-2 of the pulse laser beam stored by the control means 100 of the laser processing apparatus 1 according to the second embodiment has zero energy at the base of the Gaussian distribution over the entire circumference. Distribution. Further, the energy distribution ED-2 of the pulse laser beam LB irradiated by the laser beam irradiation means 20 of the laser processing apparatus 1 according to the second embodiment is a Gaussian distribution over the entire circumference as shown in FIG.

  When adjusting the energy distribution ED-2 of the pulsed laser beam LB, the control unit 100 of the laser processing apparatus 1 according to the second embodiment measures the output measuring unit 70 when all the driving mechanisms of the digital mirror device 22 are turned on. As shown in FIG. 10, the energy distribution ED-2 of the pulsed laser beam LB is a Gaussian distribution. Then, the control means 100 of the laser processing apparatus 1-2 turns off the drive mechanism that changes the direction of the mirror 25 at the outer edge of the digital mirror device 22 indicated by parallel oblique lines in FIG. The energy distribution ED-2 of the pulse laser beam LB is adjusted to the ideal energy distribution IE-2.

  According to the laser processing apparatus 1 according to the second embodiment, a portion where the difference between the energy distributions ED-2 and IE-2, which is a desired portion of the pulse laser beam LB, exceeds a predetermined value by the digital mirror device 22 as in the first embodiment. Since P can be thinned out, the energy distribution ED-2 of the pulse laser beam LB can be easily changed.

[Modification 1 and Modification 2]
Laser processing apparatuses according to Modification 1 and Modification 2 of Embodiments 1 and 2 will be described with reference to the drawings. FIG. 13 is a diagram illustrating an ideal energy distribution of the pulsed laser beam stored by the control unit of the laser processing apparatus according to the first modification of the first and second embodiments, and FIG. 14 illustrates the first and second embodiments. It is a figure which shows the ideal energy distribution of the pulse laser beam memorize | stored by the control means of the laser processing apparatus which concerns on the modification 2. In FIG. 13 and FIG. 14, the same parts as those in the first and second embodiments are denoted by the same reference numerals and description thereof is omitted.

  The ideal energy distribution IE-3 of the pulsed laser beam LB stored by the control means 100 of the laser processing apparatus 1 according to the modified example 1 has a top hat shape in which the energy of the central portion of the Gaussian distribution is uniform as shown in FIG. There is no. In the first modification, the laser processing apparatus 1 uses the digital mirror device 22 to adjust the energy distribution ED of the pulsed laser beam LB irradiated to the workpiece W to the top hat distribution over the entire circumference. Further, the ideal energy distribution IE-4 of the pulsed laser beam LB stored by the control unit 100 of the laser processing apparatus 1 according to the modified example 2 is such that the energy of the central part of the Gaussian distribution is larger than that of the outer peripheral part as shown in FIG. It has a weak satellite shape. In the first embodiment, the laser processing apparatus 1 uses the digital mirror device 22 to adjust the energy distribution ED of the pulse laser beam LB irradiated to the workpiece W to the satellite distribution over the entire circumference.

  As in the first or second embodiment, the laser processing apparatus 1 according to the first and second modifications has the energy distributions ED, IE-3, and IE− that are desired portions of the pulsed laser beam LB by the digital mirror device 22. Since the portion P where the difference of 4 exceeds a predetermined value can be thinned out, the energy distribution ED of the pulse laser beam LB can be easily changed. Further, since the laser processing apparatus 1 according to the first and second modifications can adjust the energy distribution ED of the pulsed laser beam LB to an arbitrary distribution, the first hat can be controlled to the top hat distribution in the first modification and the satellite distribution in the second modification. . Furthermore, since the laser processing apparatus 1 according to the first and second modifications irradiates the pulse laser beam LB with a top hat distribution, the laser processing apparatus 1 is formed with the pulse laser beam LB in the removal of the functional layer (Low-k film) by ablation processing. The edge of the laser-processed groove becomes sharp, and the effect that the peeling of the functional layer can be suppressed is also achieved.

[Modification 3]
A laser processing apparatus according to Modification 1 of Embodiments 1 and 2 will be described with reference to the drawings. FIG. 15 is a diagram illustrating a schematic configuration example of a laser beam irradiation unit of a laser processing apparatus according to Modification 3 of Embodiment 1 and Embodiment 2. In FIG. 15, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 15, the laser beam irradiation means 20-3 of the laser processing apparatus 1-3 according to the modification 3 pulsates the pulsed laser beam LB as parallel light between the laser beam oscillator 21 and the digital mirror device 22. A beam expander 26 that expands the outer diameter of the spot of the laser beam LB is set.

In the laser processing apparatus 1-3 according to the modified example 3, the difference between the energy distributions ED and IE that are desired portions of the pulse laser beam LB exceeds the predetermined value by the digital mirror device 22 as in the first or second embodiment. Since the portion P can be thinned out, the energy distribution ED of the pulse laser beam LB can be easily changed. In addition, since the laser processing apparatus 1 adjusts the energy distribution ED of the pulse laser beam LB by the digital mirror device 22 that electrically switches, the spot shape of the pulse laser beam LB that finally enters the condenser lens 23 is an arbitrary shape. Can be adjusted.

  Further, in the laser processing apparatus 1-3 according to the third modification, since the beam expander 26 is set between the laser beam oscillator 21 and the digital mirror device 22, each mirror of the laser beam oscillator 21 and the digital mirror device 22 is set. 25 can be optically connected, and the energy distribution ED of the pulse laser beam LB can be reliably changed by the digital mirror device 22.

  The present invention is not limited to the first embodiment, the second embodiment, and the first to third modifications. That is, various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 10 Chuck table 10a Holding surface 20, 20-3 Laser beam irradiation means 21 Laser beam oscillator 22 Digital mirror device 23 Condensing lens 26 Beam expander 100 Control means W Workpiece LB Pulse laser beam P The part exceeding a predetermined value ( Desired part)
IE, IE-2, IE-3, IE-4 Ideal energy distribution ED, ED-2 Energy distribution

Claims (3)

A laser processing apparatus comprising: a chuck table that holds a workpiece; and a laser beam irradiation unit that irradiates and processes the workpiece held on the chuck table by irradiating a pulse laser beam,
The laser beam irradiation means
A laser beam oscillator that oscillates a pulsed laser beam;
A digital mirror device that adjusts the energy distribution of the oscillated pulsed laser beam;
A condensing lens that condenses the pulsed laser beam incident through the digital mirror device;
Control means for controlling the digital mirror device,
The digital mirror device is a laser processing apparatus that adjusts the energy distribution of a pulsed laser beam by thinning out a desired portion of the pulsed laser beam.   The laser processing apparatus according to claim 1, wherein the digital mirror device is used to adjust the energy distribution of the pulsed laser beam applied to the workpiece to a Gaussian distribution or a top hat distribution.   The laser processing apparatus according to claim 1, wherein a beam expander is set between the laser beam oscillator and the digital mirror device.

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