KR101094319B1 - Laser beam machining apparatus and machining method - Google Patents

Abstract

A laser processing apparatus and processing method are disclosed. A laser generating unit for generating a laser beam, a laser beam receiving the laser beam, and emitting a first beam during processing, a first light modulator for emitting a second beam during processing, and receiving a first beam during processing Emits a third beam, and when not processed, receives a second beam to emit a fourth beam, and receives a third beam or a fourth beam from the second light modulator to irradiate a target position. A laser processing apparatus including an objective lens unit that modulates a laser beam using two or more AOMs, and maintains maximum energy efficiency by using zero-order diffracted light of each AOM during processing, that is, when using a laser beam. When not processing, that is, when the laser beam is not used, each AOM is operated so that the non-diffracted laser beam passes through each AOM to minimize its energy efficiency, thereby not affecting the laser processing quality. You can rock.

Laser, machining, AOM

Description

Laser beam machining apparatus and machining method

The present invention relates to a laser processing apparatus and a processing method.

The processing apparatus using a laser irradiates a laser beam at a very local place in a non-contact manner with respect to the object to be removed, destroys, marks, or performs a desired target without surrounding damage.

The quality of the laser processing is affected by the material and size of the object to be processed, the energy intensity distribution of the irradiated laser beam, the size of the laser beam spot, and the accuracy of the irradiation position, and the AOM (Acoustic Optic) Optical modulators such as modulators, acousto-optic modulators).

AOM is a device using the 'acoustic optical effect', which is an effect of periodically changing the refractive index of light by modifying the medium by sound waves or ultrasonic waves.Acoustic optical effect causes the medium to act as a phase grating and diffracts light such as a laser beam. Done. The intensity and the diffraction angle of the diffracted light through the AOM vary depending on the intensity and frequency of the sound wave, respectively, and are applied to the amplitude modulation and deflection of the laser beam using this property.

In general, AOM consists of an electrode attached to an acoustooptic medium, and an electro-acoustic modulator that generates acoustic acoustic waves in response to an electrical signal applied from a drive circuit through the electrode. When the RF signal from the driving circuit is applied to the electro-acoustic modulator, the electro-acoustic modulator generates an acoustic wave surface in the acoustooptic medium, whereby a laser beam of a predetermined wavelength incident on the incident surface of the acoustooptic medium is Bragg is reflected on the acoustic wave surface and emitted as first order diffracted light, and a part of the incident laser beam is emitted as 0th order diffracted light without diffraction at the acoustic wave surface.

As described above, even when the AOM is operated to diffract the laser beam, a part of the incident laser beam is not diffracted and is emitted in the path of the 0th order diffracted light, which is ultimately irradiated to the object through the laser optical system, thereby causing laser processing quality. There is a problem that can adversely affect.

The background art described above is technical information possessed by the inventors for the derivation of the present invention or acquired during the derivation process of the present invention, and is not necessarily a publicly known technique disclosed to the general public before the application of the present invention.

The present invention provides a laser processing apparatus and a processing method using energy of maximum efficiency when processing with a laser beam, and allowing only minimal energy to pass through the optical system so as not to affect the laser processing quality when not processing. To provide.

According to an aspect of the present invention, a laser generating unit for generating a laser beam, a first light modulator for receiving a laser beam, and emits a first beam during processing, and emits a second beam during non-processing, A second light modulator for receiving a first beam to emit a third beam during processing, a second light modulator for receiving a second beam to emit a fourth beam, and a third beam or a fourth beam from the second light modulator Provided is a laser processing apparatus including an objective lens unit for receiving a beam and irradiating a target position.

The first light modulator and the second light modulator may include an acoustic optic modulator (AOM), in which case the first beam and the third beam are zero-order diffracted light passing through the AOM, and the second and fourth beams May be light emitted in a path of zeroth order diffracted light as the AOM diffracts the laser beam.

In addition, a shutter interposed on the optical path of the laser beam, and may block the laser beam from being irradiated to the target position (shutter), the operation of the shutter is the operation of the first light modulator and the second light modulator. And can be synchronized (syncronization).

On the other hand, according to another aspect of the present invention, a laser generating unit for generating a laser beam, a plurality of AOM arranged to receive and modulate the laser beam, and optically connected, and receives a laser beam modulated by the plurality of AOM And an objective lens unit configured to be irradiated to a target position, wherein the plurality of AOMs are stopped to emit zero-order diffracted light during processing, and are operated to diffract the laser beam during non-processing. A processing apparatus is provided. The shutter may be interposed on an optical path of a laser beam to block the laser beam from being irradiated to the target position and may be operated in synchronization with a plurality of AOMs.

On the other hand, according to another aspect of the present invention, (a) generating a laser beam, (b) during the processing to the laser beam is emitted as a zero-order diffracted light through the first AOM, (c) during Causing the laser beam emitted from the first AOM to emit zeroth order diffracted light through the second AOM; and (d) receiving the laser beam emitted from the second AOM to be irradiated to a target position of the object to be processed. A laser processing method is provided that includes.

Step (b) includes operating the first AOM such that the laser beam is diffracted through the first AOM when it is not processed, and step (c) is characterized in that the laser beam exiting from the first AOM when it is not processed is second Operating the second AOM to be diffracted through the AOM.

After step (a), it may further comprise the step of blocking the laser beam is irradiated to the target position by operating the shutter during the non-processing.

After step (c), the laser beam emitted from the second AOM is emitted through the third AOM during processing, and the laser beam emitted from the second AOM is emitted through the third AOM during processing. Operating the third AOM to be diffracted.

Other aspects, features, and advantages other than those described above will become apparent from the following drawings, claims, and detailed description of the invention.

According to a preferred embodiment of the present invention, two or more AOMs are used to modulate the laser beam, while maintaining energy efficiency at the maximum by using zero-order diffracted light of each AOM when processing, i.e., using a laser beam. In other words, when the laser beam is not used, each AOM is operated so that a laser beam transmitted without diffraction passes through each AOM to minimize its energy efficiency, thereby not affecting the laser processing quality.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, and in the following description with reference to the accompanying drawings, the same or corresponding components are given the same reference numerals and redundant description thereof will be omitted. Shall be.

1 is a block diagram showing the configuration of a laser processing apparatus according to an embodiment of the present invention, Figure 2 is a block diagram showing an operating state of the AOM according to an embodiment of the present invention. 1 and 2, a laser generator 1, a first AOM 10, a second AOM 12, an objective lens 14, and a shutter 16 are illustrated.

This embodiment is characterized in that in the process of processing an object such as a multi-layer substrate using a laser beam, to improve the energy transfer efficiency of the optical path transfer device such as AOM to precise processing to the desired energy.

When the energy transfer efficiency of the AOM is low during laser processing, the laser beam having a desired level of energy cannot be irradiated. In this embodiment, the energy transfer and blocking efficiency is improved by using two or more AOMs. .

In the laser processing apparatus according to the present embodiment, the laser generation unit 1 generates a laser beam to pass through two or more light modulators, and then irradiates the laser beam to a target position of the object to be processed through the objective lens 14. By doing so, the object is processed. The laser generating unit 1 is composed of a laser medium, a pumping unit, a switching unit and the like to emit a laser beam having a predetermined pulse width. The laser beam oscillated by the laser generator 1 may be an ultra-short pulsed laser beam having a pulse width in femto-second or pico-second units.

When using a laser beam having an extremely short pulse, the pulse duration is shorter than the thermal diffusion time, so that the target exposed to the laser beam with high energy intensity can be removed in a short time because there is no energy transfer between the electron and the lattice. As a result, a melting zone or a heat affected zone is hardly observed in the portion to which the laser beam is irradiated. In addition, the length of the laser pulse absorbed and diffused in any material is proportional to the width of the laser pulse. The ultra short laser pulse has a short duration and a diffusion length in which the laser pulse is absorbed and diffused into the processing part. It also shortens, enabling precision machining.

The light modulator separates the path of the laser beam to adjust the amount of the laser beam. Acoustic Optic Modulator (AOM), Electro Optic Modulator (EOM), Liquid Crystal Modulator, etc. may be used for the optical modulator. In this embodiment, an AOM (Acoustic Optic Modulator) is used as the optical modulator. An example will be described. Other types of light modulators may also be used instead of the AOM of this embodiment within the scope of the technical spirit of the present invention.

The first AOM 10 which modulates the laser beam generated from the laser generator 1 emits the first beam during processing, that is, when the object is to be processed using the laser beam, and during non-processing. In other words, the laser beam is operated to emit the second beam when the laser beam is not to be used for processing the object. For example, it may be operated to diffract an incident laser beam during non-processing so that zero-order diffracted light is emitted during processing. As a result, some non-diffracted laser beams may be emitted in the same path as the zeroth order diffracted light.

The second AOM 12, which modulates the light emitted from the first AOM 10, receives the first beam and emits a third beam at the time of processing, and receives the second beam at the time of non-processing to produce the fourth beam. It works to exit. For example, it may be operated to receive the 0th order diffracted light during processing and to emit it back to the 0th order diffracted light, and to receive some laser beams which are not diffracted at the time of non-processing and to be diffracted again to the diffraction light. . Accordingly, some laser beams, which are also not diffracted, may be emitted in the same path as the zeroth order diffracted light.

For example, when processing a femtosecond laser having a high repetition rate of 80 MHz with a high energy of 100 mW, the first diffracted light is diffracted by diffracting the laser beam generated from the laser generator 1. In this case, the energy level may drop to 90 mW while passing through an intermediate optical system such as AOM, and laser processing may be difficult as a result of using an intermediate optical system having a low energy conversion efficiency.

Therefore, in order to improve the energy conversion efficiency of the AOM, it is possible to use a zero-order diffracted light that passes through the AOM without diffracting the laser beam, in which case part of the process of diffracting the laser beam to block the laser beam during non-processing The laser beam is not diffracted and is emitted in the path of the 0th order diffracted light, which may act as a factor that adversely affects laser processing. For example, assuming that the energy modulation efficiency of the primary diffracted light is 85%, the remaining 15% of energy may pass through the AOM and be irradiated onto the object to be processed, thereby degrading laser processing quality.

That is, looking at the operating mechanism of the AOM shown in Figure 2, the modulation efficiency of the laser beam through the AOM can be calculated as shown in the following equation (1).

Q = 2πλ ₀ L / (nΛ ² ) (1)

Here, Q is a modulation efficiency (Quality factor), λ ₀ is the wavelength of the laser beam, L is the distance of the laser beam receiving sound waves, n is the refractive index of the acoustic optical medium (crystal), Λ is the wavelength of the sound wave.

In this embodiment, as shown in Figure 1, the two AOM (10, 12) is arranged so as to be optically connected, while maintaining the energy transfer efficiency at nearly 100% during processing, while energy is transmitted through the AOM when not processed It can be lowered so as not to affect the processing quality. Here, the term 'optically connected' means that the light emitted from the previous component is located in the next component and is positioned before and after the same optical path.

For example, as shown in FIG. 2, when the first diffracted light of the AOM has an energy modulation efficiency of 85%, the first AOM 10 and the second AOM 12 are optically connected during processing. When used, the zero-order diffracted light exhibits an energy transfer efficiency of almost 100%, and when the first AOM 10 and the second AOM 12 are simultaneously operated to diffract the laser beam when not processed, the first AOM 10 and the first AOM 10 2 The energy penetrating the AOM 12 falls below 2.25% (15% 15%).

In other words, the laser can be effectively processed by letting the 0th-order diffracted light be emitted during the actual processing, and when not processed, the two AOMs (10, 12) are operated to diffract the laser beam to achieve energy of 2.25% or less. Only light having it can be irradiated to the object to be processed, and this amount of energy does not affect the processing quality.

As in the above example, when two AOMs (10, 12) are connected to block the laser beam, about 97.75% (100% -2.25%) of energy can be blocked, which is an energy cutoff when using one AOM. Compared with 85% of efficiency, it shows a very high degree of blocking efficiency, which enables an efficient laser machining operation.

That is, assuming that the maximum diffraction efficiency of the AOM is 85%, simultaneously operating or stopping the first AOM and the second AOM, the maximum value of the energy of the laser beam transmitted through the optical path of the zero-order diffracted light Can be more than 99% and the minimum can be less than 2.25%.

In the above case, laser processing uses the light transmitted through the optical path of the 0th order diffracted light (laser beam of 99% or more energy), and even when not processed, the minimum beam energy of 2.25% is applied to the object to be processed. Will not affect.

By applying this principle, a number of additional AOMs can be installed to increase the degree of energy cutoff during non-machining, so that only lasers with a lower ratio than 2.25% when using the two AOMs described above are irradiated to the workpiece. can do.

Furthermore, since the zeroth order diffracted light is used for the actual processing and the optical path is not converted to the zeroth order diffracted light, the stability of the laser beam is further improved as compared with the case where the first order diffracted light is used to convert the optical path. The advantage is that more stable machining operations are possible.

In this way, the laser beam modulated through the plurality of AOM is irradiated to the target position of the object to be processed through the objective lens 14, thereby laser processing.

On the other hand, in order to block the laser beam irradiated to the object to be processed, a shutter 16 may be interposed on the optical path of the laser beam. That is, the shutter 16 may be further installed to completely block up to some laser beams passing through the AOM during non-processing, in which case the shutter 16 synchronizes with the operation of the AOM, so that the AOM emits zero-order diffracted light during processing. The shutter 16 is opened to allow the laser beam of sufficient energy to be irradiated to the target position, and when the AOM diffracts the laser beam during non-processing, the shutter 16 is closed so that some unbeamed laser beam is not irradiated to the target position. You can block.

The shutter 16 according to the present embodiment may be installed at any position of the laser optical system within the range for performing the above-described function.

In FIG. 1, a case in which two AOMs are installed is described as an example, but three or more AOMs may be used to derive the same effect as in the above-described embodiment.

3 is a flowchart illustrating a laser processing method according to an embodiment of the present invention. Hereinafter, a process of performing laser processing using the laser processing apparatus according to the present embodiment will be described.

First, a laser beam is generated from the laser generation unit 1 (S10), and the laser beam is transmitted through two AOMs optically connected, that is, the first AOM 10 and the second AOM 12. In laser processing, the laser beam passes through the first AOM 10 and is emitted as the 0th diffracted light (S20), and the laser beam transmitted through the first AOM 10 passes through the second AOM 12 to 0 It is emitted by the diffracted light (S30). As such, the laser beams passing through the two AOMs 10 and 12 are irradiated to the target position of the object to be processed to perform a laser machining operation (S40).

On the other hand, during the non-processing operation of all the plurality of AOM to diffract the laser beam. That is, the first AOM 10 is operated to diffract the laser beam incident on the first AOM 10 (S22), and thus, some non-diffracted laser beam passes through the first AOM 10 and is emitted. The laser beam transmitted through the first AOM 10 is incident on the second AOM 12, and the second AOM 12 is operated to diffract the laser beam incident on the second AOM 12 (S32). Only some laser beams that are not diffracted are transmitted through the second AOM 12 to be emitted. On the other hand, a laser beam (eg, primary diffracted light) diffracted and separated into a separate path may be received and bypassed by a beam dump (D 'in FIG. 1).

For example, when 85% of the laser beam energy incident on the AOM is diffracted and 15% is emitted through the AOM when not processed, 15% of the energy emitted through the first AOM 10 is emitted to the second AOM. Incident to (12) and diffracted, in this process only 15% of the energy incident on the second AOM 12, i.e. only 2.25% (15% x 15%) of the laser incident on the first AOM 10 2 is emitted through the AOM (12). Therefore, the ratio of energy transmitted to both of the two AOMs 10 and 12 when irradiated to the object to be processed is low so as not to affect the processing quality.

By applying this principle, additional AOMs (eg 3rd AOM, 4th AOM,…) can be installed to increase the degree of energy cutoff during raw processing, which is lower than when using the two AOMs described above. Only a laser of the ratio can be made to irradiate the object to be processed.

Furthermore, in order to block the laser beam irradiated to the object to be processed in the non-processing, it may be operated via the shutter 16 on the optical path of the laser beam (S38). That is, the shutter 16 may be further installed to completely block up to some laser beams passing through the AOM during non-processing, in which case the shutter 16 synchronizes with the operation of the AOM, so that the AOM emits zero-order diffracted light during processing. Shutter 16 is opened to allow the laser beam of sufficient energy to be irradiated to the target position, and when AOM diffracts the laser beam during non-processing, the shutter 16 is closed to irradiate the laser beam to some non-diffraction laser beam. Can be blocked.

In this way, the laser beam transmitted through the plurality of AOM is irradiated to the target position of the object to be processed with the energy of the maximum efficiency during processing, the laser processing operation is performed, the minimum energy (2.25% in the above example) Only below) is irradiated to the object to be processed does not adversely affect the processing quality (S40).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

1 is a block diagram showing the configuration of a laser processing apparatus according to an embodiment of the present invention.

Figure 2 is a block diagram showing the operating state of the AOM according to an embodiment of the present invention.

3 is a flow chart showing a laser processing method according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

1: laser generating unit 10: 1st AOM

12: second AOM 14: objective lens

16: shutter

Claims (12)

A device that improves the energy transfer efficiency and the blocking efficiency of a laser beam by using two or more light modulators, A laser generator for generating a laser beam, a first light modulator for receiving the laser beam, a second light modulator for receiving light from the first light modulator, and light from the second light modulator Including an objective lens unit for receiving the light to the target position of the object to be processed, In raw material, The first light modulator is operated to diffract the laser beam such that the diffracted light is bypassed through a beam dump and transmits the non-diffracted light; The second light modulator is operated to diffract light transmitted through the first light modulator, such that the diffracted light is bypassed through a beam dump, and the light that is not diffracted is transmitted; The energy level of light transmitted through the second light modulator to the target position is lowered such that the object is not processed by a laser beam; In processing, The first light modulator stops operating so as not to diffract the laser beam, thereby transmitting the laser beam; The second light modulator stops its operation so as not to diffract the light transmitted through the first light modulator, and transmits the light transmitted through the first light modulator; And the energy level of the light transmitted through the second light modulator to the target position is maintained at the energy level of the laser beam in the laser generator. The method of claim 1, The first optical modulator and the second optical modulator comprises an AOM (Acoustic Optic Modulator). delete delete The method of claim 1, And a shutter interposed on the optical path of the laser beam and blocking the laser beam from being irradiated to the target position. The method of claim 5, And the operation of the shutter is synchronized with the operation of the first light modulator and the second light modulator. The method of claim 1, Interposed between the second light modulator and the objective lens unit, When not processed, it is operated to diffract the light transmitted through the second light modulator so that the diffracted light is bypassed through a beam dump, and the light that is not diffracted is transmitted, At the time of processing, the operation is stopped so as not to diffract the light transmitted through the second light modulator, thereby transmitting the light transmitted through the second light modulator, Laser processing apparatus further comprises at least one third light modulator. delete A method of processing an object using the laser processing apparatus of claim 1, (a) generating the laser beam; (b) when unprocessed, the first light modulator diffracts the laser beam such that the diffracted light is bypassed through a beam dump and transmits the undiffracted light; Diffracting the light transmitted through the first light modulator to allow the second light modulator to bypass the diffracted light through a beam dump, and to transmit light that is not diffracted; (c) during processing, the first light modulator transmits the laser beam without diffracting the laser beam; Transmitting the light transmitted through the first light modulator without diffracting the light transmitted through the first light modulator; And and (d) receiving the light passing through the second light modulator and irradiating it to a target position of the object to be processed. delete 10. The method of claim 9, After the step (a), further comprising the step of blocking the laser beam from being irradiated to the target position by operating the shutter during non-processing. 10. The method of claim 9, The laser processing apparatus further includes at least one third optical modulator interposed between the second optical modulator and the objective lens unit. After step (c), During non-processing, the light transmitted through the second light modulator is diffracted so that the diffracted light is bypassed through the beam dump, and the light that is not diffracted is transmitted. At the time of processing, the light transmitted through the second light modulator is transmitted without diffracting the light transmitted through the second light modulator, Laser processing method further comprising the step of operating the third light modulator.

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