JP2020151769A - Laser processing device - Google Patents

Abstract

To provide a laser processing device allowing observation of distribution of a laser beam induced by a liquid jet.SOLUTION: A laser processing device (10) to irradiate a workpiece with a laser beam induced by a liquid jet comprises laser beam distribution control means which changes distribution of a laser beam induced by a liquid jet by changing the incidence position and incidence angle of the laser beam relative to the liquid jet.SELECTED DRAWING: Figure 1

Description

The present invention relates to a laser processing apparatus, a laser processing method, a laser light distribution observation apparatus, and a laser light distribution observation method, and more particularly to a technique for observing the distribution of laser light guided by a liquid jet.

In recent years, with the increasing integration and miniaturization of devices such as ICs and LSIs, inorganic films such as SiOF and BSG (SiOB) and polymer films such as polyimide and parylene have been applied to the surface of semiconductor substrates such as silicon. A wafer in which a device layer made of a laminated body in which a low dielectric constant insulator film (Low-k film) made of a certain organic film and a functional film forming a circuit are laminated has been put into practical use.

However, dicing of a wafer having such a device layer tends to cause film peeling, burrs, and the like, which is a big problem in the dicing process. In particular, when the Low-k film is contained in the device layer, the Low-k film is very brittle, so that there is a problem that the Low-k film is likely to be peeled off when the dicing blade is used for cutting. That is, when cut by a dicing blade, the Low-k film is destroyed, and when this destroyed region expands to the device forming region (chip forming region), the chip becomes a defective product and the yield of the manufactured semiconductor device is lowered. It becomes a factor to end up.

In order to solve the above problem, a technique for forming a laser processing groove along a planned division line called a street to divide a device layer and then cutting with a dicing blade prior to cutting with a dicing blade is disclosed. (See, for example, Patent Document 1).

However, the technique disclosed in Patent Document 1 requires a laser processing device (laser scriber) in addition to the dicing device. Further, in the laser irradiation step, in order to form a laser processing groove wider than the width of the dicing blade, the laser irradiation must be reciprocated along one street. Therefore, there is a problem that productivity is poor and cost is increased.

On the other hand, Patent Document 2 discloses a laser processing apparatus that injects a pressurized liquid with a liquid jet and irradiates a work piece with laser light using the liquid jet as an optical waveguide. In this laser processing device, since the liquid jet is ejected toward the workpiece, the laser beam is guided toward the workpiece without being diffused by the liquid jet while preventing the effects of heat damage and contamination during machining. Therefore, it is possible to perform high-precision processing. In addition, a dicing step such as dicing with a dicing blade or laser dicing becomes unnecessary.

Further, Patent Document 2 discloses an observation device for observing the output of a laser beam induced by a liquid jet. This observation device has a shielding material that can shield the liquid jet and transmit the laser light, and a measuring means behind the shielding material, and causes the laser light to enter the measuring means through the shielding material to output the laser light. I try to measure. According to this, the output of the laser beam guided by the liquid jet can be directly measured, and the problem of the laser beam output can be detected in advance.

Japanese Unexamined Patent Publication No. 2006-140311 Japanese Patent No. 5072691

However, the conventional observation device disclosed in Patent Document 2 is mainly used for measuring the output of a laser beam, and therefore, observing the distribution of the laser beam at the contact surface between the liquid jet and the workpiece. Can't.

Further, when the workpiece is processed by the laser beam induced by the liquid jet, there is a problem that the shape of the processing mark changes even if the processing conditions (for example, the length of the liquid jet) are slightly different. Therefore, in order to process the workpiece with an arbitrary processing mark shape, preliminary processing is required, which causes a decrease in productivity and an increase in cost.

The present invention has been made in view of such circumstances, and is a laser processing apparatus capable of observing the distribution of laser light induced by a liquid jet, a laser processing method, a laser light distribution observing apparatus, and a laser beam distribution. The purpose is to provide an observation method.

In order to achieve the above object, the laser processing apparatus according to the first aspect of the present invention collects a work table for holding a work piece, a laser oscillator that outputs a laser beam, and a laser beam output from the laser oscillator. It has a shining condensing lens and a liquid jet injection nozzle that injects a liquid jet toward the work piece, and guides the laser light focused by the condensing lens into the liquid jet to make it a liquid jet. The processing head is provided with a processing head that irradiates the induced laser light toward the workpiece and a laser light distribution observation device that observes the distribution of the laser light induced by the liquid jet. The laser light distribution observation device is a processing head. A shielding plate that shields the liquid jet and transmits the laser beam guided by the liquid jet, which is arranged at the same height as the workpiece, and the laser beam transmitted through the shielding plate are imaged. The imaging lens, the optical detector that is arranged in a positional relationship conjugate with the shielding plate with respect to the imaging lens and receives the laser beam imaged by the imaging lens, and the output signal output from the optical detector. Based on this, an image data acquisition means for acquiring laser light distribution image data showing the distribution of laser light on the contact surface between the liquid jet and the shielding plate, and a display means for displaying the laser light distribution image data acquired by the image data acquisition means. And have.

Note that "the height relative to the workpiece relative to the machining head" means that the distance between the machining head and the shielding plate is equal to the distance between the machining head and the workpiece. To do. That is, it means that the length of the liquid jet when the liquid jet is ejected from the machining head to the workpiece and the length of the liquid jet when the liquid jet is jetted from the machining head to the shielding plate are equal to each other. Therefore, it is not always necessary that the workpiece and the shielding plate have the same height in absolute coordinates. For example, even when the work piece and the shielding plate have different heights in absolute coordinates, the heights relative to the processing head may be the same.

The laser processing apparatus according to the second aspect of the present invention includes, in the first aspect, a laser beam distribution control means for changing the distribution of the laser beam on the contact surface between the liquid jet and the shielding plate.

In the second aspect of the laser processing apparatus according to the third aspect of the present invention, the laser light distribution control means changes the distribution of the laser light by changing the length of the liquid jet.

In the second or third aspect, the laser processing apparatus according to the fourth aspect of the present invention includes a laser beam deflecting means that is arranged between the laser oscillator and the condenser lens and deflects the laser beam, and has a laser beam distribution. The control means changes the distribution of the laser beam by controlling the laser beam deflecting means so that the incident position and the incident angle of the laser beam with respect to the liquid jet change.

The laser processing apparatus according to the fifth aspect of the present invention is a beam shape shaping means that is arranged between the laser oscillator and the condensing lens in any one of the second to fourth aspects and shapes the laser beam. The laser beam distribution control means changes the distribution of the laser beam by controlling the beam shape shaping means so that the shape, size, or intensity distribution of the laser beam changes.

The laser processing apparatus according to the sixth aspect of the present invention includes a pressurized liquid supply means for supplying a pressurized liquid to the processing head in any one of the second to fifth aspects, and has a laser beam distribution. The control means changes the distribution of the laser beam by controlling the pressure of the pressurized liquid supplied by the pressurized liquid supply means.

In the laser processing apparatus according to the seventh aspect of the present invention, in any one of the second to sixth aspects, the laser light distribution control means controls the nozzle diameter of the liquid jet injection nozzle to obtain the laser light. Change the distribution.

The laser processing method according to the eighth aspect of the present invention is a condensing step of condensing the laser beam output from the laser oscillator, a liquid jet is ejected toward the work piece, and is condensed by the condensing step. Observe the liquid jet injection step of irradiating the workpiece with the laser beam guided by the liquid jet by guiding the laser beam into the liquid jet, and the distribution of the laser beam guided by the liquid jet. The laser beam distribution observation step includes a laser beam distribution observation step, in which the liquid jet is shielded by a shielding plate and the laser beam guided by the liquid jet passes through the shielding plate and the shielding plate is transmitted. An imaging process in which the formed laser beam is imaged by an imaging lens, and the laser beam imaged by the imaging lens is received by an optical detector arranged in a positional relationship conjugate with the shielding plate with respect to the imaging lens. The light receiving step, the acquisition step of acquiring the laser beam distribution image data showing the distribution of the laser beam on the contact surface between the liquid jet and the shielding plate, and the laser beam distribution image data based on the output signal output from the light detector. It has a display step of displaying.

In the eighth aspect, the laser processing method according to the ninth aspect of the present invention includes a laser light distribution control step for changing the distribution of the laser light on the contact surface between the liquid jet and the shielding plate.

The laser beam distribution observation device according to the tenth aspect of the present invention is a shielding plate that shields a liquid jet and transmits a laser beam guided by the liquid jet, and an imaging lens that forms an image of a laser beam transmitted through the shielding plate. A liquid that is arranged in a positional relationship conjugate with the shielding plate with respect to the imaging lens and receives the laser beam imaged by the imaging lens, and an output signal output from the optical detector. An image data acquisition means for acquiring laser light distribution image data showing the distribution of laser light on the contact surface between the jet and the shielding plate, and a display means for displaying the laser light distribution image data acquired by the image data acquisition means. Be prepared.

The laser beam distribution observation method according to the eleventh aspect of the present invention includes a laser beam transmission step in which a liquid jet is shielded by a shielding plate and the laser beam guided by the liquid jet passes through the shielding plate, and a laser transmitted through the shielding plate. The imaging process in which light is imaged by an imaging lens, and the light reception in which the laser beam imaged by the imaging lens is received by an optical detector arranged in a positional relationship conjugate with the shielding plate with respect to the imaging lens. Based on the process and the output signal output from the light detector, the acquisition process for acquiring the laser beam distribution image data showing the distribution of the laser beam on the contact surface between the liquid jet and the shielding plate, and the laser beam distribution image data are displayed. The display process is provided.

According to the present invention, since the shielding plate and the photodetector are arranged in a positional relationship conjugate with each other with respect to the imaging lens, the distribution of the laser beam on the contact surface between the liquid jet and the shielding plate can be measured by the photodetector. It can be faithfully reproduced on the light receiving surface. This makes it possible to observe the distribution of the laser beam guided by the liquid jet, so that the shape of the processing mark can be easily predicted without performing preliminary processing. As a result, the overall throughput is improved and the cost can be reduced.

Schematic diagram showing the configuration of the laser processing apparatus according to the present embodiment Simplified diagram showing the laser beam path in a liquid jet The figure which showed the result of observing the distribution of the laser beam at the position shown by a of FIG. The figure which showed the result of observing the distribution of the laser beam at the position shown by b of FIG. The figure which showed the depth profile of the machined groove when the linear machined groove was formed in the work under the same conditions as FIG. The figure which showed the depth profile of the machined groove when the linear machined groove was formed in the work under the same conditions as FIG. A flowchart showing an example of a laser processing method using the laser processing apparatus according to the present embodiment. Simplified diagram showing the laser beam path when the laser beam is incident on the peripheral part of the liquid jet instead of the central axis. The figure which showed the result of actually observing the distribution of the laser beam when the laser beam was made to enter the peripheral part instead of the central axis of the liquid jet. The figure which showed the depth profile of the machined groove when the linear machined groove was formed in the work under the same conditions as FIG. The figure which showed the formation example of the groove shape by the beam shape shaping means

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic view showing a configuration of a laser processing apparatus according to the present embodiment.

As shown in FIG. 1, the laser processing apparatus 10 according to the present embodiment includes a laser power supply 12, a laser oscillator 14, a work table 16, a work table moving unit 18, a liquid supply means 20, and a head unit 22. The laser beam distribution observation device 26 and the control unit 30 are provided.

The laser power supply 12 is connected to the laser oscillator 14 via a signal cable to supply electric power to the laser oscillator 14.

The laser oscillator 14 outputs the laser beam L using the electric power supplied from the laser power supply 12. As the laser beam L, a laser beam in a wavelength range that is difficult to be absorbed by water is used.

The work table 16 has a holding surface 16a that attracts and holds the work W (workpiece). A plurality of suction holes for sucking and holding the work W are provided on the holding surface 16a, and the suction holes are connected to a vacuum suction source (not shown).

The work table moving unit 18 includes an X table 32 and a θ rotation table 34. The X table 32 is installed horizontally and is configured to be movable in the X direction by an X drive mechanism (not shown). The θ rotary table 34 is arranged on the X table 32 and is configured to be movable in the θ direction (rotation direction centered on the axis in the Z direction) by a θ drive mechanism (not shown). Then, the work table 16 is placed and fixed on the θ rotation table 34. Therefore, the work table 16 is configured to be movable in the X direction and the θ direction, respectively.

The liquid supply means 20 is connected to the processing head 40 of the head unit 22 via a liquid supply path, and supplies a pressurized liquid (for example, pressurized water) to the processing head 40.

The head unit 22 includes a deflection portion 36, a beam shape shaping means 38, and a processing head 40. The head unit 22 is arranged on a Z table configured to be movable in the Z direction by a Z drive mechanism (not shown). The Z table is arranged in a Y table configured to be movable in the Y direction by a Y drive mechanism (not shown). Therefore, the head unit 22 is configured to be movable in the Y direction and the Z direction.

The deflection unit 36 is provided on the optical path of the laser beam L, and reflects the laser beam L output from the laser oscillator 14 toward the processing head 40. The deflection unit 36 is configured by facing two galvano mirrors (not shown) that can swing around axes orthogonal to each other, and swings the two galvano mirrors to deflect the laser beam L. Therefore, the incident angle and the incident position with respect to the liquid jet J ejected from the processing head 40 (liquid jet injection nozzle 48) can be changed. The deflection unit 36 is an example of the laser beam deflection means.

The beam shape shaping means 38 is arranged between the deflection unit 36 and the processing head 40, and shapes the laser beam L input from the laser oscillator 14 via the deflection unit 36. The beam shape shaping means 38 is composed of, for example, a variable aperture (rectangular or circular), an axicon lens, a beam homogenizer, and a mechanism for minutely moving these in a direction orthogonal to the laser beam L. The laser beam L before being incident on the lens is shaped into a predetermined shape, size, and intensity distribution. In addition, AOD (acoustic optical element), SLM (spatial modulation element), DMD (Digital Mirror Device), diffraction element, calcite, etc. are used to statically or dynamically generate the laser light L, including the branching of the laser light L. It is also possible to shape it.

The processing head 40 injects the pressurized liquid supplied from the liquid supply means 20 toward the work W by the liquid jet J, and guides the laser beam L into the liquid jet J to guide the liquid jet J. The work W is irradiated with the laser beam L guided by the above. The specific configuration of the processing head 40 is as follows.

The processing head 40 includes a condensing lens 42 and a head body 44.

The condensing lens 42 is arranged in the front stage (upper side) of the head body 44, and condenses the laser beam L incident from the laser oscillator 14 via the deflection portion 36 and the beam shape shaping means 38 toward the inside of the head body 44. To do.

A liquid chamber 46 is partitioned inside the head body 44. The liquid chamber 46 accommodates the high pressure liquid supplied from the liquid supply means 20. A liquid jet injection nozzle 48 is provided in the lower part of the head body 44, and the liquid jet injection nozzle 48 communicates with the liquid chamber 46. Therefore, when the high-pressure liquid is supplied from the liquid supply means 20 to the processing head 40, the pressurized liquid is housed in the liquid chamber 46, and the work W (or laser beam distribution observation described later) is further observed from the liquid jet injection nozzle 48. The liquid jet J is injected toward the shielding plate 52) of the device 26.

A window portion 50 is provided on the upper portion of the head main body 44. The window portion 50 is composed of a light transmitting member (for example, quartz glass) that is optically transparent to the laser light L, seals the liquid chamber 46, and transmits the laser light L. Therefore, the laser beam L emitted from the condensing lens 42 passes through the window portion 50, enters the inside of the head body 44 (liquid chamber 46), and condenses on the liquid jet injection nozzle 48.

In the present embodiment, as an example, the work table 16 is configured to be movable in the X direction and the θ direction, and the head unit 22 is configured to be movable in the Y direction and the Z direction. The table 16 and the head unit 22 need only be configured to be relatively movable in the X direction, the Y direction, the Z direction, and the θ direction, and another embodiment different from the present embodiment may be appropriately adopted. it can.

The laser beam distribution observing device 26 is arranged at a position facing the processing head 40 instead of the work table 16 when observing the distribution of the laser beam L guided by the liquid jet J.

The laser beam distribution observation device 26 includes an observation device drive mechanism (not shown), and is configured to be movable in the X direction, the Y direction, and the Z direction. As a result, the laser beam distribution observation device 26 can move between the observation position facing the processing head 40 and the retracted position separated from the observation position.

The laser beam distribution observation device 26 includes a shielding plate 52, a liquid removing means 54, an imaging lens 56, a photodetector 58, a signal processing unit 62, and a monitor 64.

The shielding plate 52 is provided on the upper surface (the surface facing the processing head 40) of the laser beam distribution observation device 26. The shielding plate 52 is composed of a light transmitting member (for example, quartz glass) that is optically transparent to the laser light L, shields the liquid jet J, and transmits the laser light L. Therefore, the liquid of the liquid jet J ejected from the liquid jet injection nozzle 48 of the processing head 40 is shielded by the shielding plate 52, while the laser beam L guided by the liquid jet J passes through the shielding plate 52 and the laser. It is incident inside the main body 60 that constitutes the light distribution observation device 26.

The shielding plate 52 is arranged at the same height as the work W held on the work table 16 with respect to the processing head 40. In the present embodiment, the distance between the processing head 40 and the shielding plate 52 may be equal to the distance between the processing head 40 and the work W. That is, the length of the liquid jet J when the liquid jet J is ejected from the machining head 40 to the work W and the length of the liquid jet J when the liquid jet J is jetted from the machining head 40 to the shielding plate 52 are mutually exclusive. It suffices if they are equal, and it is not always necessary that the work W and the shielding plate 52 have the same height in absolute coordinates. For example, even when the work W and the shielding plate 52 have different heights in absolute coordinates, the heights relative to the processing head 40 may be the same. The distance between the processing head 40 and the shielding plate 52 becomes equal to the distance between the processing head 40 and the work W due to the movement of the head unit 22 (processing head 40) or the laser beam distribution observation device 26 in the Z direction. Is adjusted so that.

The liquid removing means 54 removes the liquid (residual liquid) of the liquid jet J shielded by the shielding plate 52. As the liquid removing means 54, for example, a liquid absorbing means for removing residual liquid by absorption, a liquid suction means for removing residual liquid by suction, a liquid blowing means for removing residual liquid by blowing air, or a combination thereof is appropriately used. Can be adopted. As the liquid absorbing means, it is preferable to adopt a configuration in which a fibrous strip-shaped member such as a cloth is brought into contact with the surface of the shielding plate 52 to absorb the residual liquid into the strip-shaped member by utilizing the capillary phenomenon. it can.

The imaging lens 56 is arranged between the shielding plate 52 and the photodetector 58 inside the main body 60. The imaging lens 56 is composed of a plurality of lenses, and projects the distribution of the laser beam L guided by the liquid jet J onto the light receiving surface of the photodetector 58. That is, the shielding plate 52 and the photodetector 58 are arranged in a positional relationship conjugate with each other with respect to the imaging lens 56, and the distribution of the laser beam L on the contact surface between the liquid jet J and the shielding plate 52 is imaged. The lens 56 faithfully reproduces the light receiving surface of the photodetector 58.

The photodetector 58 receives a projected image showing the distribution of the laser beam L imaged by the imaging lens 56. The photodetector 58 has a plurality of light receiving elements arranged two-dimensionally, and each light receiving element outputs an output signal (electric signal) according to the amount of received light. As the photodetector 58, for example, a solid-state image sensor such as a CCD image sensor (Charge Coupled Device Image Sensor) or a CMOS image sensor (Complementary Metal Oxide Semiconductor Image Sensor) is preferably used. The output signal output from each light receiving element of the photodetector 58 is input to the signal processing unit 62.

The signal processing unit 62 is connected to the photodetector 58, and acquires and acquires image data (laser beam distribution image data) indicating the distribution of the laser beam L based on the output signal output from the photodetector 58. The laser beam distribution image data is displayed on the monitor 64. The signal processing unit 62 is an example of the image data acquisition means. The monitor 64 is an example of display means.

The signal processing unit 62 includes a determination unit 66. The determination unit 66 determines whether or not the laser beam distribution image data shows an appropriate laser beam distribution, and displays the determination result on the monitor 64.

In the present embodiment, as an example, the laser beam distribution observation device 26 includes a memory unit (not shown) that stores one or a plurality of reference image data showing an appropriate laser beam distribution. The determination unit 66 determines whether or not the laser beam distribution image data and the reference image data stored in the memory unit match by using a known image comparison method such as pattern matching.

The control unit 30 includes a CPU, a memory, an input / output circuit unit, various control circuit units, and the like, and controls the operation of each unit of the laser processing apparatus 10.

FIG. 2 is a simplified diagram showing a laser beam path in the liquid jet J when the laser beam L is incident coaxially with the central axis of the liquid jet J. Since the liquid jet J has the same function as the SI type multimode optical fiber, the moving speed of the liquid jet J in the central axis direction (longitudinal direction) actually changes depending on the approach angle to the liquid jet J. , They interfere with each other, and it is considered that the liquid jet J is complicated by speckle noise generated by the minute unevenness of the cylindrical outer peripheral surface (cylindrical surface) of the liquid jet J, but here is a simplified diagram for the sake of simplicity. Will be described using.

As shown in FIG. 2, when the laser beam L condensed by the condensing lens 42 is incident on the central axis of the liquid jet J, the laser beam L repeats expansion and contraction by total reflection in the liquid jet J. It is guided along the central axis direction. For example, since the position shown by a in FIG. 2 corresponds to the antinode portion of the laser beam path (the portion where the laser beam L is enlarged), the cross-sectional shape of the laser beam L at that position (the cross-sectional shape perpendicular to the central axis of the liquid jet J). ) Spreads uniformly over the entire liquid jet diameter. On the other hand, since the position shown by b in FIG. 2 corresponds to the node portion of the laser beam path (the portion where the laser beam L is reduced), the laser beam L is gathered only in a narrow range at the center of the liquid jet J.

FIG. 3 is a diagram showing the results of actually observing the distribution of the laser beam L at the positions shown in a of FIG. 2 and FIG. 4 at the positions corresponding to the positions shown in b of FIG. Further, FIG. 5 is a diagram showing the depth profile of the machined groove when a linear machined groove is formed on the work W under the same conditions as in FIG. 4, respectively.

As can be seen from these figures, the distribution of the laser beam L guided by the liquid jet J changes depending on the position in the central axis direction of the liquid jet J, that is, the length of the liquid jet J, and further, the distribution of the laser beam L. The shape of the machined mark also changes according to the change in.

Therefore, by controlling to change the distribution of the laser beam L, it is possible to control the shape of the processing mark to a desired shape by selecting an arbitrary distribution of the laser beam L from the distribution of the plurality of laser beams L. it can.

Next, a laser processing method using the laser processing apparatus 10 according to the present embodiment will be described with reference to FIG. 7. FIG. 7 is a flowchart showing an example of a laser processing method using the laser processing apparatus 10 according to the present embodiment. Unless otherwise specified, each process is executed under the control of the control unit 30.

(Step S10: Laser beam distribution acquisition step)
The laser beam distribution acquisition step is performed prior to the laser processing of the work W.

First, the laser beam distribution observation device 26 moves to an observation position (a position facing the processing head 40) by an observation device drive mechanism (not shown). The shielding plate 52 is arranged at the same height as the work W held on the work table 16 with respect to the processing head 40.

Next, the pressurized liquid is supplied from the liquid supply means 20 to the processing head 40. The pressurized liquid supplied to the processing head 40 is housed in the liquid chamber 46, and the liquid jet J is further injected from the liquid jet injection nozzle 48 toward the shielding plate 52.

Further, the laser beam L output from the laser oscillator 14 is deflected toward the processing head 40 by the deflection unit 36, shaped into a predetermined shape, size, and intensity distribution by the beam shape shaping means 38, and becomes the condensing lens 42. Incident. Further, the laser beam L is condensed by the condenser lens 42 to the liquid jet injection nozzle 48 through the window portion 50. As a result, the laser beam L is guided by the liquid jet J, guided by the liquid jet J, and irradiated toward the shielding plate 52.

On the other hand, the liquid jet J ejected from the liquid jet injection nozzle 48 is shielded by the shielding plate 52, and the laser beam L guided by the liquid jet J passes through the shielding plate 52 and is emitted by the imaging lens 56. An image is formed on the light receiving surface of the detector 58. At that time, since the shielding plate 52 and the photodetector 58 are arranged in a positional relationship optically conjugate with each other with respect to the imaging lens 56, the laser beam L at the contact surface between the liquid jet J and the shielding plate 52 The distribution is faithfully reproduced on the light receiving surface of the photodetector 58 by the imaging lens 56.

When a projected image showing the distribution of the laser beam L is formed on the light receiving surface of the photodetector 58 in this way, each light receiving element of the photodetector 58 outputs an output signal according to the amount of light received to the signal processing unit 62. Output to.

The signal processing unit 62 acquires image data (laser light distribution image data) showing the distribution of the laser light L based on the output signals output from each light receiving element of the photodetector 58, and obtains the acquired laser light distribution image data. Displayed on the monitor 64.

Therefore, the user can observe the distribution of the laser beam L on the contact surface between the liquid jet J and the shielding plate 52 (corresponding to the distribution of the laser beam L on the contact surface between the liquid jet J and the work W). .. As a result, it is possible to easily predict the shape of the machining mark when the work W is machined by the machining head 40 without performing preliminary machining.

Further, the liquid (residual liquid) of the liquid jet J shielded by the shielding plate 52 is removed by the liquid removing means 54. Therefore, the distribution of the laser beam L can be observed stably and accurately without being affected by the scattering of the laser beam L by the residual liquid on the shielding plate 52.

(Step S12: Laser beam distribution determination step)
Next, the determination unit 66 in the signal processing unit 62 determines whether or not the laser light distribution image data acquired in the laser light distribution observation step (step S10) shows an appropriate laser light distribution. In the present embodiment, as an example, the determination unit 66 uses a known image comparison method such as pattern matching to combine the laser beam distribution image data and the reference image data stored in the memory unit (not shown). Determine if you are doing it. If the laser beam distribution image data is not appropriate (No), the process proceeds to step S14, and if the laser beam distribution image data is appropriate (Yes), the process proceeds to step S16.

(Step S14: Laser beam distribution changing step)
When it is determined in the laser beam distribution determination step (step S12) that the laser beam distribution image data is not appropriate, the control unit 30 controls to change the distribution of the laser beam L. There are several possible modes in which the control unit 30 changes the distribution of the laser beam L. The control unit 30 is an example of the laser beam distribution control means.

<First aspect>
In the first aspect, the control unit 30 moves the head unit 22 in the Z direction by a preset amount of movement, whereby the distance between the processing head 40 of the head unit 22 and the shielding plate 52 (work W). That is, control is performed to change the length of the liquid jet J. As a result, as shown in FIGS. 3 and 4, the distribution of the laser beam L on the contact surface between the liquid jet J and the shielding plate 52 (work W) is uniformly spread over the entire liquid jet diameter (FIG. 3). (3, see FIG. 5) or a state in which the liquid jet J is gathered only in a narrow range at the center (see FIGS. 4 and 6). For example, when it is desired to obtain a U-shaped machining mark shape with the liquid jet width, the laser beam distribution as shown in FIG. 3 is selected, and when it is desired to obtain a machining mark shape thinner than the liquid jet width, FIG. The laser beam distribution as shown in the above may be selected. This makes it possible to obtain a desired processing mark shape.

<Second aspect>
As a second aspect, the control unit 30 controls the incident angle and the incident position of the laser beam L with respect to the liquid jet J by controlling the directions of the two galvanometer mirrors arranged in the deflection unit 36. As a result, the laser beam L can be set to a donut-shaped distribution.

FIG. 8 is a simplified diagram showing a laser beam path when the laser beam L is incident on the peripheral portion in a state of being tilted diagonally rather than coaxially with the central axis of the liquid jet J, and the liquid jet J is on the upstream side (liquid). It is a figure corresponding to the case of observing from the jet injection nozzle 48 side) to the downstream side (work W side). In this case, the laser beam path travels in the central axis direction while spirally rotating in the liquid jet J along the cylindrical outer peripheral surface (cylindrical surface) of the liquid jet J. , The abdominal portion and the node portion formed at the positions a and b in FIG. 2 are not formed, and the distribution of the laser beam L and the shape of the processing mark do not change significantly even if the length of the liquid jet J changes.

FIG. 9 is a diagram showing the results of actually observing the distribution of the laser beam L when the laser beam L is incident on the liquid jet J as shown in FIG. Further, FIG. 10 is a diagram showing a depth profile of the machined groove when a linear machined groove is formed in the work W under the same conditions as in FIG. As can be seen from FIGS. 9 and 10, when the laser beam L is incident on the peripheral portion in a state of being tilted diagonally rather than coaxially with the central axis of the liquid jet J, the laser beam L has a donut-shaped distribution (FIG. 9). 9), the shape of the machined mark formed at this time is a flattened bottom surface of the machined groove as compared with the case shown in FIGS. 5 and 6.

As described above, the second aspect is a suitable aspect when it is desired to flatten the bottom surface of the machined groove. Further, since the distribution of the laser beam L and the shape of the processing mark do not change significantly even if the length of the liquid jet J changes, the processing stability against a change in the minute length of the liquid jet J can be improved.

<Third aspect>
As a third aspect, the control unit 30 changes the shape, size, or intensity distribution of the laser beam L before it is incident on the condensing lens 42 by controlling the beam shape shaping means 38. For example, when the beam diameter of the laser beam L is changed by the beam shape shaping means 38, the numerical aperture of the laser beam L condensed by the condensing lens 42 changes. As a result, the laser beam path in the liquid jet J changes, so that the distance between the processing head 40 and the shielding plate 52 (work W) (that is, the length of the liquid jet J) is set as in the first aspect. The distribution of the laser beam L and the shape of the processing mark can be changed without changing the laser beam L, and it is possible to obtain a U-shaped processing mark shape with a liquid jet width or a processing mark shape thinner than the liquid jet width. ..

Further, when it is desired to obtain a processing mark shape smaller than the liquid jet width, the laser beam L may be shaped into a slit shape by the beam shape shaping means 38. In this case, since the distribution of the laser beam L extends in the direction blocked by the slit due to the diffraction effect, it is possible to obtain a processing mark shape thinner than the liquid jet width.

The beam shape shaping means 38 may be composed of, for example, a variable aperture (rectangular or circular), an axicon lens, a beam homogenizer, and a mechanism for minutely moving these in a direction orthogonal to the laser beam L. It is possible. In addition, the distribution of the laser beam L can be controlled statically or dynamically by using AOD (acoustic optical element), SLM (spatial modulation element), DMD (Digital Mirror Device), or by using a diffraction element or a grating. It is also possible to control the shape of the machining mark by shaping the laser beam L by branching it. For example, by unevenly distributing the distribution of the laser beam L by the beam shape shaping means 38, it is possible to form a groove shape as shown in FIG.

<Fourth aspect>
As a fourth aspect, the control unit 30 controls to change the pressure of the pressurized liquid of the liquid supply means 20. For example, as the pressure of the pressurized liquid is increased, the outer wall of the liquid jet J is slightly disturbed, so that the pressure distribution of the liquid jet J becomes sparse. In this case, the distribution of the laser beam L becomes a uniform distribution as a whole, and a U-shaped processing mark shape can be obtained with the liquid jet width.

<Fifth aspect>
As a fifth aspect, the control unit 30 controls to change the nozzle diameter (diameter) of the liquid jet injection nozzle 48. In this case, the nozzle diameter of the liquid jet injection nozzle 48 is configured to be variable by control by the control unit 30. As another aspect, an arbitrary machining head 40 can be selected from a plurality of machining heads 40 having different nozzle diameters of the liquid jet injection nozzle 48 according to the control of the control unit 30 (or a user's instruction). It may be configured.

According to the fifth aspect, the liquid jet diameter is changed by changing the nozzle diameter of the liquid jet injection nozzle 48. As a result, the distribution of the laser beam L induced by the liquid jet J changes, and the shape of the processing mark can be changed according to the change.

The control unit 30 may perform control to change the distribution of the laser beam L by appropriately combining a plurality of the above-mentioned first to fifth aspects.

After the laser beam distribution changing step is performed as described above, the process returns to step S10, the signal processing unit 62 reacquires the laser beam distribution image data, and the determination unit 66 determines that the laser beam distribution image data is appropriate. The same process is repeated until it is determined.

(Step S16: Laser processing step)
When the laser beam distribution image data is determined to be appropriate in the laser beam distribution determination step (step S12), the laser processing step is performed. When the laser processing step is performed, the laser light distribution observation device 26 moves to the retracted position.

First, the work W sucked and held on the holding surface 16a of the work table 16 is aligned in the θ direction and positioned in the XY direction by an alignment means (not shown). The work W is placed on the work table 16 with the surface of the work W (the surface on which the device layer is formed) facing upward.

When the alignment is completed, the liquid jet J is ejected from the liquid jet injection nozzle 48 of the processing head 40 toward the work W while moving in the X direction on the X table 32, and the laser beam L guided by the liquid jet J is ejected. Is irradiated to the work W. As a result, a processing groove having a predetermined depth is formed in the work W along the planned division line without causing film peeling or burrs.

When the formation of the machined groove of one line is completed, the Y table to which the head unit 22 is attached is indexed in the Y direction, and the machined groove is formed in the same manner on the next line.

When the machined grooves are formed along all the planned cutting lines parallel to the X direction, the θ rotary table 34 is rotated by 90 °, and all the machined grooves are formed in the same manner for the lines orthogonal to the previous line.

As described above, according to the present embodiment, in the laser beam distribution observation device 26, the shielding plate 52 and the photodetector 58 are arranged in a positional relationship conjugate with each other with respect to the imaging lens 56, so that the liquid jet The distribution of the laser beam L at the contact surface between J and the shielding plate 52 (corresponding to the distribution of the laser beam L at the contact surface between the liquid jet J and the work W) can be faithfully reproduced on the light receiving surface of the photodetector 58. it can. As a result, the distribution of the laser beam L guided by the liquid jet J can be observed, so that the shape of the machining mark can be easily predicted without performing preliminary machining. As a result, the overall throughput is improved and the cost can be reduced.

Further, according to the present embodiment, the control unit 30 controls to change the distribution of the laser beam L. Therefore, by selecting an arbitrary distribution of the laser beam L from the distribution of the plurality of laser beams L. The shape of the machined mark can be controlled to a desired one.

In the present embodiment, as an example, the determination unit 66 provided in the signal processing unit 62 automatically determines whether or not the laser beam distribution image data shows an appropriate laser beam distribution. However, the present invention is not limited to this, and for example, the user may determine whether or not the laser beam L distribution is desired by checking the laser beam distribution image data displayed on the monitor 64. Good. In this case, the signal processing unit 62 does not need the determination unit 66.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above examples, and it goes without saying that various improvements and modifications may be made without departing from the gist of the present invention. ..

10 ... Laser processing device, 12 ... Laser power supply, 14 ... Laser oscillator, 16 ... Work table, 16a ... Holding surface, 18 ... Work table moving part, 20 ... Liquid supply means, 22 ... Head unit, 26 ... Laser light distribution observation Device, 30 ... Control unit, 32 ... X table, 34 ... θ rotation table, 36 ... Deflection unit, 38 ... Beam shape shaping means, 40 ... Machining head, 42 ... Condensing lens, 44 ... Head body, 46 ... Liquid chamber , 48 ... Liquid jet injection nozzle, 50 ... Window, 52 ... Shielding plate, 54 ... Liquid removing means, 56 ... Imaging lens, 58 ... Optical detector, 60 ... Main body, 62 ... Signal processing unit, 64 ... Monitor , 66 ... Judgment unit, L ... Laser beam, J ... Liquid jet

Claims (5)

A laser processing device that irradiates a work piece with a laser beam induced by a liquid jet.
The laser beam distribution control means for changing the distribution of the laser beam guided by the liquid jet by changing the incident position and the incident angle of the laser beam with respect to the liquid jet is provided.
Laser processing equipment. The laser beam distribution control means changes the distribution of the laser beam guided by the liquid jet by changing the injection pressure of the liquid jet.
The laser processing apparatus according to claim 1. A laser processing device that irradiates a work piece with a laser beam induced by a liquid jet.
The laser beam distribution control means for changing the distribution of the laser beam guided by the liquid jet by changing the injection pressure of the liquid jet is provided.
Laser processing equipment. The laser beam distribution control means changes the distribution of the laser beam guided by the liquid jet by changing the diameter of the liquid jet.
The laser processing apparatus according to any one of claims 1 to 3. A laser processing device that irradiates a work piece with a laser beam induced by a liquid jet.
The laser beam distribution control means for changing the distribution of the laser beam guided by the liquid jet by changing the diameter of the liquid jet is provided.
Laser processing equipment.