JP4219241B2 - Laser processing apparatus and laser processing method - Google Patents

Description

  The present invention relates to a laser processing apparatus and a laser processing method using a laser beam, and more particularly to a laser processing apparatus and a laser processing method for processing a workpiece by irradiating a laser beam toward the workpiece in a liquid. .

  2. Description of the Related Art A laser processing apparatus using laser light is known as an apparatus that performs processing such as drilling and cutting on a workpiece. This laser processing apparatus is being adopted in the semiconductor manufacturing process because precise microfabrication is possible by appropriately selecting a laser, and it is used for thin films such as insulating films and metal films formed on the surface of a substrate. These thin films are selectively removed by irradiating a laser beam.

  Generally, a laser processing apparatus includes a laser light source that generates laser light and laser waveguide means that guides the laser light from the laser light source to a workpiece. Laser light generated by the laser light source is irradiated toward the workpiece from a lens (laser light emitting portion) disposed at the end of the laser waveguide means. By irradiation with such laser light, an ablation phenomenon occurs in the workpiece, and the workpiece can be processed by this ablation phenomenon. Unlike the conventional mechanical processing, this ablation phenomenon has little thermal influence on the workpiece, and can significantly reduce physical and thermal damage to the workpiece caused by the processing.

  By the way, at the time of laser processing, since laser light is irradiated in a state where the lens (laser light emitting portion) is opposed to the workpiece, the processing dust scattered from the workpiece adheres to the surface of the lens. Machining scraps may interfere with processing. As a countermeasure for this, for example, as disclosed in Patent Document 1, the lens at the end of the laser waveguide means and the workpiece are both placed in water so that the processing waste scattered from the workpiece does not adhere to the lens. In addition, a technique for forming a high-speed water flow along a workpiece portion of a workpiece has been proposed.

JP-A-6-142971

  However, when using a high-power laser for speeding up the processing, or when bringing the lens close to the work piece for fine processing, the above-described high-speed water flow alone causes the processing dust to adhere to the lens. May not be sufficient to prevent. For this reason, in the conventional laser processing apparatus, the energy density of the laser beam may be reduced due to the processing dust attached to the lens, and there is a problem that the processing speed cannot be increased and precise fine processing cannot be performed.

  The present invention has been made to solve the above-described conventional problems, and prevents the processing dust from adhering to the laser beam emitting portion disposed at the end of the laser waveguide means, thereby increasing the processing speed and precision. An object of the present invention is to provide a laser processing apparatus and a laser processing method capable of performing fine processing.

  In order to achieve the above-described object, one embodiment of the present invention includes a laser light source that generates laser light, a holding unit that holds a workpiece, and a container that immerses the workpiece and the holding unit in a liquid. And laser waveguide means for guiding laser light from the laser light source to the workpiece, and a protective member disposed between the laser light emitting portion of the laser waveguide means and the workpiece, The protective member is a laser processing apparatus that is made of a material that transmits laser light.

  According to the present invention, by providing the protective member, it is possible to prevent the processing waste scattered from the workpiece from adhering to the laser light emitting portion of the laser waveguide means, and this prevents the processing waste. The workpiece can be irradiated with laser light without any problem.

Moreover, according to this invention, the processing waste adhering to a protection member can be moved from the optical path of a laser beam with a protection member, and the transparency of a protection member can be maintained favorable.

Before SL liquid flow generating mechanism that generates a flow of liquid may further comprise between the protective member and the workpiece.
According to the present invention, since the processing waste can be transferred to the downstream side by the flow of liquid, the amount of processing waste attached to the protective member can be reduced.

Further comprising a cleaning means for cleaning the surface facing the workpiece before Symbol protective member, the cleaning means, so as not interfere with the flow of liquid generated by irradiation and the liquid flow generating mechanism of the laser beam It may be arranged at any position.
According to the present invention, since the processing waste adhering to the protection member can be removed by the cleaning means, laser processing can be continuously performed.

It may be inclined by a predetermined angle with respect to a plane perpendicular to the workpiece surface optical axis of the laser light which faces the front Symbol protective member.
According to the present invention, it is possible to prevent the laser light irradiated from the laser light emitting portion of the laser waveguide means from being reflected by the protective member and returning to the laser light source, and to prevent the laser light source from being damaged by the reflected light. Can do. Further, it is possible to prevent the reflected light reflected from the surface of the work piece from being further reflected by the protective member and irradiated again to the work piece, and the work portion of the work piece can be multi-processed. Can be prevented.

In another aspect of the present invention, the workpiece is held by a holding portion, the workpiece is immersed in the liquid, and the laser light emitting portion of the laser waveguide means is immersed in the liquid so as to face the workpiece. A protective member made of a material that transmits laser light is disposed between the laser light emitting portion and the workpiece, and the laser light is moved while moving the protective member in a direction crossing the laser light. Is irradiated to the workpiece in the liquid from the laser beam emitting portion via the laser waveguide means .
In this case, before Symbol while generating a flow of liquid between the protective member and the workpiece may be irradiated with laser light to the workpiece.
Further, the workpiece may be irradiated with the laser beam while the surface of the protective member facing the workpiece is cleaned at a position that does not hinder the irradiation of the laser beam .
The surface of the protective member facing the workpiece may be inclined by a predetermined angle with respect to a plane perpendicular to the optical axis of the laser beam.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that the processing waste scattered from the to-be-processed object adheres to the laser beam emission part of a laser waveguide means. Therefore, it is possible to prevent the energy density of the laser beam from being lowered due to the processing waste, and it is possible to increase the processing speed and perform precise microfabrication.

Hereinafter, a laser processing apparatus according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing the overall configuration of the laser processing apparatus according to the first embodiment of the present invention.
As shown in FIG. 1, a laser processing apparatus includes a laser light source 1 that generates laser light having a predetermined wavelength and predetermined energy, a holding unit 3 that holds a workpiece 2, a workpiece 2 and a holding unit. 3 and a laser waveguide means 5 for guiding laser light from the laser light source 1 to the workpiece 2. The laser waveguide means 5 includes a reflecting mirror 8 that changes the optical path of laser light, a lens barrel 9, and a lens 10 attached to the outlet of the lens barrel 9. The lens 10 is disposed so as to face the workpiece 2 held by the holding unit 3, and is configured as a laser beam emitting unit that emits laser light toward the workpiece 2. The holding unit 3 is placed on the base 17 accommodated in the container 4, and the workpiece 2 is placed and held on the upper part of the holding unit 3.

  The holding unit 3 is connected to a horizontal moving mechanism 12 fixed to the base 17, and the holding unit 3 is moved in the horizontal direction by the horizontal moving mechanism 12. A vertical movement mechanism 14 is connected to the base 17, and the holding unit 3 is moved in the vertical direction by the vertical movement mechanism 14 via the base 17. With such a configuration, the workpiece 2 on the holding unit 3 can be moved relative to the lens 10. The horizontal movement mechanism 12 and the vertical movement mechanism 14 constitute a relative movement mechanism for moving the workpiece 2 relative to the lens 10. A predetermined liquid 13 is supplied into the container 4 from a liquid supply source (not shown), and the holding unit 3 and the workpiece 2 held by the holding unit 3 are immersed in the liquid 13. As the liquid 13, water (including pure water) is preferably used. Examples of the workpiece 2 include metals, resins, composite materials, and insulating films and metal films formed on semiconductor wafers.

In the above-described configuration, the laser light generated by the laser light source 1 changes its traveling direction by the reflecting mirror 8, passes through the lens barrel 9, and is condensed or diffused by the lens 10 disposed at the exit of the lens barrel 9. . The laser light that has passed through the lens 10 passes through the liquid 13 in the container 4, reaches the workpiece 2 held by the holding unit 3, and is subjected to predetermined processing. The wavelength of the laser light is appropriately selected according to the type of the workpiece 2, but is preferably a wavelength that allows the liquid 13 to pass through without being absorbed by the liquid (water) 13 in the container 4. In this embodiment, a YAG laser is used as the laser light source 1, but the laser light source of the present invention is not limited to this. For example, a CO ₂ laser or the like can be used depending on the type of processing.

  The laser processing apparatus according to the present embodiment includes a flat plate-shaped protection member 15 disposed between the lens 10 and the workpiece 2. The protective member 15 is made of a material that transmits laser light, and is disposed substantially perpendicular to the optical axis of the laser light irradiated from the lens 10 (the center line of the optical path of the laser light). A movement mechanism 16 is connected to the protection member 15, and the movement mechanism 16 moves the protection member 15 in a direction substantially perpendicular to the optical axis of the laser beam (a direction crossing the laser beam). The material constituting the protection member 15 is preferably a material that does not substantially absorb laser light and has high transparency so as not to interfere with the irradiation of the workpiece 2. For example, quartz glass is preferable. Used.

  A liquid supply port 20 is provided on one side of the container 4, and a liquid discharge port 21 is provided at a position corresponding to the liquid supply port 20 on the opposite side. The liquid supply port 20 is connected to a high-pressure liquid supply source 22, and the liquid supplied from the high-pressure liquid supply source 22 flows into the container 4 through the liquid supply port 20 and is held by the holding unit 3. A high-speed liquid flow 23 is generated between the workpiece 2 and the protection member 15. The liquid discharge port 21 is disposed at the end point of the liquid flow 23, and the liquid 13 forming the liquid flow 23 is discharged from the liquid discharge port 21. In the present embodiment, a liquid flow generating mechanism is formed by the liquid supply port 20, the drainage port 21, and the high-pressure liquid supply source 22.

Next, the operation of the laser processing apparatus having the above configuration will be described below.
First, the workpiece 2 is held by the holding unit 3, and the workpiece 2 and the lens 10 of the laser waveguide means 5 are immersed in the liquid. Next, the part to be processed of the workpiece 2 is moved to the irradiation position of the laser beam by the horizontal movement mechanism 12 and the vertical movement mechanism 14. Thereafter, a liquid flow 23 is generated between the protection member 15 and the workpiece 2, and the protection member 15 is moved in a direction substantially perpendicular to the optical axis of the laser beam. In this state, the laser light source 1 is operated to generate a laser beam having a predetermined wavelength and a predetermined energy, and the laser beam is irradiated to the processing portion of the workpiece 2 through the laser waveguide means 5.

  When the laser beam is irradiated onto the processing portion of the workpiece 2, processing scraps and bubbles are generated from the processing portion. Most of these processing scraps and bubbles are conveyed by the liquid flow 23 and discharged from the drain port 21. The processing waste and bubbles that have not been transported in the liquid flow 23 adhere to the protection member 15, but the processing waste and bubbles attached to the protection member 15 move together with the protection member 15 in a direction crossing the optical path of the laser beam. There is no obstacle to continuous laser processing. If necessary, the workpiece 2 having a desired area and a desired depth is processed by irradiating the workpiece 2 with the laser light source 1 while moving the workpiece 2 in the horizontal direction and / or the vertical direction. it can.

  In this embodiment, the relative position between the lens 10 of the laser waveguide means 5 and the workpiece 2 is adjusted by moving the holding unit 3 relative to the lens 10 by the horizontal movement mechanism 12 and the vertical movement mechanism 14. However, the lens 10 and the workpiece 2 are integrally moved relative to the workpiece 2 while the position of the holding portion 3 is fixed. You may make it adjust the relative position with.

  Next, a laser processing apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic diagram showing an overall configuration of a laser processing apparatus according to the second embodiment of the present invention. Note that the configuration and operation of the present embodiment that are not specifically described are the same as those of the first embodiment described above, and therefore, redundant description thereof is omitted.

  The difference between the present embodiment and the first embodiment is the configuration of the laser waveguide means 5 and the protection member 15. As shown in FIG. 2, in this embodiment, an optical fiber 30 is used as a member constituting the laser waveguide means 5. The optical fiber 30 includes a core material (core) 31 that allows laser light to pass therethrough and a covering portion (cladding) 32 that covers the outside of the core material 31. One end of the optical fiber 30 is connected to the laser light source 1, and the laser light generated by the laser light source 1 is transmitted to the other end while totally reflecting the inside of the core material 31. A lens (laser light emitting unit) 10 is attached to the end of the optical fiber 30 in a liquid-tight manner, and the laser light is irradiated from the lens 10 toward the workpiece 2. Since the optical fiber 30 can be easily bent, the laser waveguide means 5 using the optical fiber 30 can be freely installed as compared with the laser waveguide means 5 in the first embodiment. It has the advantage of high degree.

  The protection member 15 in the present embodiment is installed to be inclined by a predetermined angle θ with respect to a plane perpendicular to the optical axis of the laser light emitted from the lens 10. This is because the reflected light from the protection member 15 is prevented from returning to the laser light source 1 and damaging the laser light source 1, and the reflected light reflected from the surface of the workpiece 2 is reflected by the protection member 15 again. This is for avoiding multiple machining of the workpiece. The protective member 15 is installed so as to incline upward from the upstream side to the downstream side of the liquid flow 23. The protection member 15 has a disk shape, and a rotation shaft 35 extending perpendicularly to the protection member 15 is fixed at the center thereof. The rotating shaft 35 is connected to a moving mechanism 16 having a motor (not shown) and the like. By driving the moving mechanism 16, the protection member 15 and the rotating shaft 35 rotate integrally. ing.

  The laser processing apparatus according to the present embodiment includes a cylindrical member (cleaning means) 37 for removing processing debris and the like attached to the surface of the protection member 15 facing the workpiece 2. The cylindrical member 37 is disposed so that the outer peripheral surface thereof is in contact with the surface of the protection member 15 on the workpiece side. Further, the cylindrical member 37 is installed at a position that does not interfere with the laser light irradiation from the lens 10 and the liquid flow 23. That is, the cylindrical member 37 is positioned above the liquid flow 23 and is further disposed at a position that is substantially symmetric with respect to the irradiation position of the laser beam with respect to the rotation shaft 35. The cylindrical member 37 is made of a material such as polyvinyl alcohol (PVA). The cylindrical member 37 is configured to be rotatable around its axis by a drive source (not shown). The cylindrical member 37 rotates in a direction in which the outer peripheral surface of the cylindrical member 37 and the surface of the protective member 15 move in opposite directions at the contact portion with the protective member 15.

  In such a configuration, the processing waste and bubbles adhering to the surface of the protection member 15 are moved from the irradiation position of the laser light to the position where the cylindrical member 37 is disposed as the protection member 15 rotates (moves). And the processing waste adhering to the surface of the protection member 15 is removed by the rotating cylindrical member 37. Thereby, the site | part of the protection member 15 irradiated with a laser beam is always maintained clean, and can transmit the laser beam irradiated from the lens 10 satisfactorily. In this way, by continuously cleaning the protective member 15 while rotating, it is possible to always irradiate the workpiece with the laser beam satisfactorily. Therefore, reliability can be improved and continuous laser processing can be stably performed.

1 is a schematic diagram illustrating an overall configuration of a laser processing apparatus according to a first embodiment of the present invention. It is a schematic diagram which shows the whole structure of the laser processing apparatus which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 2 Work piece 3 Holding part 4 Container 5 Laser waveguide means 8 Reflective mirror 9 Lens barrel 10 Lens (laser beam emitting part)
12 Horizontal movement mechanism (relative movement mechanism)
13 Liquid 14 Vertical movement mechanism (relative movement mechanism)
DESCRIPTION OF SYMBOLS 15 Protection member 16 Movement mechanism 17 Base 20 Liquid supply port 21 Drainage port 22 High pressure liquid supply source 23 Liquid flow 30 Optical fiber 31 Core material 32 Covering part 35 Rotating shaft 37 Cylindrical member (cleaning member)

Claims (8)

A laser light source for generating laser light;
A holding part for holding a workpiece;
A container for immersing the workpiece and the holding part in a liquid;
Laser waveguide means for guiding laser light from the laser light source to the workpiece;
A protective member disposed between the laser beam emitting portion of the laser waveguide means and the workpiece ;
A moving mechanism for moving the protective member in a direction crossing the laser beam ,
The laser processing apparatus, wherein the protective member is made of a material that transmits laser light.   The laser processing apparatus according to claim 1, further comprising a liquid flow generation mechanism that generates a liquid flow between the workpiece and the protection member.   The laser processing apparatus according to claim 1, wherein the moving mechanism rotates the protection member around a central portion thereof.   The cleaning means for cleaning the surface of the protection member facing the workpiece is provided at a position that does not interfere with laser light irradiation. Laser processing equipment. Hold the workpiece by the holding part and immerse the workpiece in the liquid,
The laser light emitting part of the laser waveguide means is disposed in the liquid so as to face the workpiece,
A protective member made of a material that transmits laser light is disposed between the laser light emitting portion and the workpiece,
A laser processing method, comprising: irradiating the workpiece in liquid from the laser light emitting portion through the laser waveguide means while moving the protective member in a direction crossing the laser light.   The laser processing method according to claim 5, wherein the workpiece is irradiated with laser light while generating a liquid flow between the workpiece and the protective member.   7. The laser processing method according to claim 5, wherein the workpiece is irradiated with laser light while rotating the protective member around a central portion thereof.   The laser beam is irradiated to the workpiece while cleaning the surface of the protective member facing the workpiece at a position that does not interfere with the laser beam irradiation. The laser processing method according to one item.

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