JP5805008B2 - Laser processing machine for glass fine hole processing and glass fine hole processing method - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing machine for processing glass fine holes and a method for processing glass fine holes, and in particular, a laser processing machine for processing glass fine holes and glass for forming fine holes in a glass substrate used in a semiconductor device or the like. The present invention relates to a fine hole drilling method.

  In a conventional glass laser processing method, a pulse laser beam having a pulse width of 50 to 200,000 ns and a repetition frequency of 20 to 2,000 Hz is irradiated for 0.1 to 10 seconds each time the brittle material is irradiated 1 to 5 times. A method of providing a non-irradiation time zone has been proposed (see, for example, Patent Document 1). Since the pulse laser beam is absorbed on the surface of the brittle material and vaporizes the portion, the surface of the brittle body can be processed. By irradiating the pulsed laser beam under the above conditions, the surface of the brittle material can be processed efficiently without generating cracks.

  In addition to this, in a method of irradiating a transparent glass substrate with a laser beam by a carbon dioxide laser processing machine, the transparent glass substrate is irradiated with a laser beam to form a hole, and then the glass substrate is subjected to a predetermined concentration. There has been proposed a laser processing method for immersing the substrate in a hydrofluoric acid solution to remove cracks, finely melted and solidified substances, and heat-affected portions generated in the drilled portion (see, for example, Patent Document 2).

JP-A-11-123777 JP-A-2-30390

  As described above, as a conventional glass processing method, as described in Patent Document 1, a processing method for suppressing generation of cracks in laser laser micro-hole processing of glass by providing a non-irradiation time, and Patent Document 2 In this method, etching is performed after drilling to remove residual stresses such as cracks. However, any of these methods reduces processing speed, decreases productivity, and equipment for the etching process. In addition, there are many problems in terms of cost and environment, such as the necessity of wastewater treatment.

  The present invention has been made in order to solve such problems, and provides a laser processing machine for glass micro-hole processing and a glass micro-hole processing method capable of improving productivity and reducing costs. The purpose is to obtain.

The present invention relates to a laser processing machine for processing a microscopic hole in a glass for forming a microhole in a processing object made of glass, a stage base on which the processing object is mounted, and a laser oscillator that oscillates a laser beam A beam adjustment optical system that adjusts the size or shape of the beam diameter of the laser beam oscillated from the laser oscillator, and the traveling direction of the laser beam after adjustment output from the beam adjustment optical system A light guide mirror that is adjusted toward the object to be processed mounted on a stage base, and a condensing lens that condenses the laser beam guided by the light guide mirror on a laser beam incident surface of the object to be processed; wherein the laser beam oscillated from the laser oscillator, CO ₂ laser beam or the wavelength range of a laser beam 9.0～11.0Myuemu, Serial as the pulse width of the laser beam incident on the laser beam incident surface of the object becomes. 1 to 5 [mu] s, and adjusting the pulse width of the laser beam oscillated from the laser oscillator This is a laser processing machine for processing glass fine holes.

The present invention relates to a laser processing machine for processing a microscopic hole in a glass for forming a microhole in a processing object made of glass, a stage base on which the processing object is mounted, and a laser oscillator that oscillates a laser beam A beam adjustment optical system that adjusts the size or shape of the beam diameter of the laser beam oscillated from the laser oscillator, and the traveling direction of the laser beam after adjustment output from the beam adjustment optical system A light guide mirror that is adjusted toward the object to be processed mounted on a stage base, and a condensing lens that condenses the laser beam guided by the light guide mirror on a laser beam incident surface of the object to be processed; wherein the laser beam oscillated from the laser oscillator, CO ₂ laser beam or the wavelength range of a laser beam 9.0～11.0Myuemu, Serial as the pulse width of the laser beam incident on the laser beam incident surface of the object becomes. 1 to 5 [mu] s, and adjusting the pulse width of the laser beam oscillated from the laser oscillator Since it is a laser processing machine for processing glass fine holes, it is not necessary to provide a non-irradiation time because cracks do not occur even in continuous irradiation processing by setting the pulse width of the laser beam to 1 to 5 μs . It can be shortened and productivity can be improved, and it is not necessary to carry out an etching process for removing cracks. Therefore, the equipment for the etching process and waste liquid treatment are not required, and the cost can be reduced.

It is a block diagram which shows the structure of the laser processing machine for glass fine hole processing concerning Embodiment 1 and 2 of this invention. It is a configuration diagram showing a configuration of a glass fine hole processing laser oscillator provided in a laser processing machine (triaxial orthogonal pulsed CO ₂ laser oscillator) according to a first embodiment of the present invention. It is a figure which shows the example of the processed hole which the crack generate | occur | produced. It is a figure which shows the example of the processing hole which a crack does not generate | occur | produce. It is a figure which shows the example of the processing hole which the heat affected layer and the swelling part generate | occur | produced.

Embodiment 1 FIG.
Hereinafter, a laser processing machine for processing a glass fine hole according to Embodiment 1 of the present invention will be described. Examples of the use of glass micro-drilling include a thin plate through electrode for an intermediate substrate for electrically connecting a semiconductor chip and a package substrate. As electronic devices become more sophisticated and functional, printed circuit boards are becoming more dense. The main material of the substrate is a resin, but a glass having a low coefficient of thermal expansion and high insulation is expected as an alternative material.

In the first embodiment, a pulse CO ₂ laser oscillator is used as a laser oscillator for processing fine holes in glass. Since the CO ₂ laser oscillator is a gas laser having a laser medium as CO ₂ , the running cost is lower than that of a solid-state laser, and there are advantages in terms of reliability. In addition, a pulsed laser oscillator can irradiate energy in a concentrated manner in comparison with a continuous wave (CW: Continuous Wave) laser, so that deeper processing can be performed locally. . Therefore, it is suitable for forming fine holes. A pulsed CO ₂ laser oscillator has both of these advantages.

  FIG. 1 is a diagram illustrating a configuration of a laser processing machine for processing glass fine holes according to Embodiment 1 of the present invention. In FIG. 1, the mode of the laser irradiation process by the glass micro hole processing method which concerns on this Embodiment 1 is shown.

Glass micro-hole processing laser processing machine according to the first embodiment of the present invention, as shown in FIG. 1, the pulse CO ₂ laser beam (hereinafter, simply referred to as a laser beam 22) pulsed CO ₂ laser which emits a A laser oscillator 21, a beam adjusting optical system 23 that adjusts the size and shape of the laser beam 22, a light guide mirror 24 that adjusts the traveling direction of the laser beam 22 toward the glass 28, and a light guide. A mask 25 for forming a profile of the laser beam 22, a condensing lens 26 for condensing the laser beam 22 formed by the mask 25 on the laser beam incident surface of the glass 28, and a stage base 27 on which the glass 28 is mounted. It is composed of The stage base 27 is configured to be able to scan in four stage scanning directions in the left and right and front and rear directions as indicated by the arrow 20 by a driving device (not shown). In FIG. 1, arrow 1 indicates the direction of the laser gas flow in the laser oscillator 21, arrow 2 indicates the oscillation direction of the laser beam 22 from the laser oscillator 21, and arrow 3 indicates the discharge direction in the laser oscillator 21. Is shown. As indicated by arrows 1 to 3, in the first embodiment, the gas flow, the laser beam, and the discharge direction are orthogonal to each other (triaxial orthogonal type).

  The laser processing machine for processing glass fine holes according to the first embodiment of the present invention performs the following processing with this configuration.

  First, the glass 28 to be processed is mounted on the stage base 27, and the laser beam 22 is oscillated from the laser oscillator 21.

  The laser beam 22 generated from the laser oscillator 21 is subjected to beam diameter adjustment and beam shape shaping by a beam adjustment optical system 23. The beam adjusting optical system 23 is formed by a combination of a concave lens and a convex lens. A cylindrical lens, a prism, and a diffractive optical element can be used as a beam adjusting optical system that performs beam shaping of an elliptical beam or the like.

The laser beam 22 adjusted and shaped by the beam adjusting optical system 23 is guided by the light guide mirror 24, and the profile of the laser beam 22 is shaped by the mask 25.
The mask 25 is made of a material such as copper. A hole having a shape such as a circle or an ellipse smaller than the laser diameter irradiated on the mask 25 is provided at the center of the mask 25, and the laser beam 22 is shaped into the above shape by passing through the mask 25.

  Next, the laser beam 22 formed by the mask 25 is condensed on the laser beam incident surface of the glass 28 by the condensing lens 26, and the stage base 27 is scanned, so that the desired position of the glass 28 is obtained. Then, a fine processed hole 29 is formed. Examples of the type of the processing hole 29 include a blind hole or a through hole. In the first embodiment, the stage base 27 is configured to scan in the stage scanning direction 20. However, the present invention is not limited to this, and it is only necessary to perform relative scanning between the glass 28 and the laser beam 22. Therefore, even if the stage base 27 is fixed and the laser beam 22 is scanned by a galvanometer mirror, a polygon mirror, or the like, the same effect can be obtained. Therefore, it is preferable to use an Fθ lens as the condenser lens 26 for irradiation.

  In the first embodiment, as shown in FIG. 1, the mask 25 is installed. However, the mask 25 is not necessarily installed, and the condensing lens 26 is used without installing the mask 25. The glass 28 may be processed by collecting light.

  Further, an assist gas may be used for laser processing. The assist gas is an auxiliary gas used for preventing the melt from adhering to the condenser lens 26 in addition to removing the melt during processing and cooling the sample. Examples of the assist gas include air, nitrogen, and argon gas. There are two methods of flowing the assist gas: a method of flowing the gas between the condenser lens 26 and the glass 28, and a method of flowing the gas coaxially with the laser beam 22 irradiated on the glass 28 using a nozzle. In the first embodiment, the processing is performed while an assist gas is allowed to flow between the condenser lens 26 and the glass 28. You may make it flow on the same axis as the laser beam 22 with which the glass 28 is irradiated.

In the first embodiment, the pulse CO ₂ laser oscillator is used as the laser oscillator 21. However, among the pulse CO ₂ laser oscillators, in particular, a triaxial orthogonal CO that generates a pulse by a gain switch. It is desirable to use a _two laser oscillator.

In recent years, two main types of CO ₂ laser oscillators are a triaxial orthogonal type and a high-speed axial flow type. The three-axis orthogonal type is a laser oscillator having a configuration in which the directions of gas flow, laser beam, and discharge indicated by arrows 1 to 3 are orthogonal to each other, while the high-speed axial flow type is a gas flow, laser beam, and discharge direction. The laser oscillator has a configuration in which all directions are the same.

In both the three-axis orthogonal type and the high-speed axial type, it is necessary to suppress overheating of the laser gas in order to maintain the gain necessary for laser light amplification, and forced convection is used to prevent overheating of the laser gas heated by the discharge. Cooling. When the same gain is obtained, the cross-sectional area of the gas flow path is large in the three-axis orthogonal type, so high output can be obtained even at low gas pressure and low gas flow rate, while the cross-sectional area of the high-speed axial flow type is small. Since the pressure loss is large, a high gas pressure and a high gas flow rate are required. For this reason, the high-speed axial flow CO ₂ laser oscillator is inferior in amplification performance in principle because it has a higher running cost and poor cooling performance than the three-axis orthogonal CO ₂ laser oscillator.

In addition to the three-axis orthogonal type and the high-speed axial flow type, the CO ₂ laser oscillator includes a slab type. The slab type CO ₂ laser oscillator is a naturally cooled laser oscillator in which gas is completely sealed and the interval between discharge electrodes is short. Therefore, compared with other CO ₂ lasers, the gain is low and the laser is a low peak / long pulse laser, so it cannot be used for fine hole drilling of glass.

For the above reasons, in the first embodiment, a three-axis orthogonal CO ₂ laser oscillator is adopted as the laser oscillator 21, and among these, a three-axis orthogonal pulse CO ₂ laser oscillator is selected.

The configuration of the three-axis orthogonal pulse CO ₂ laser oscillator will be described below. FIG. 2 is a diagram showing a configuration of a triaxial orthogonal pulse CO ₂ laser as the laser oscillator 21 in the first embodiment of the present invention.

As shown in FIG. 2, the three-axis orthogonal pulse CO ₂ laser oscillator as the laser oscillator 21 in the first embodiment of the present invention has an optical resonance having a total reflection mirror 11 and a partial reflection mirror 12 functioning as an output mirror. , Discharge electrodes 8 and 9 provided for the optical resonator, dielectric plates 6 and 7 for fixing and supporting the discharge electrodes 8 and 9, and high voltage for applying an alternating voltage to the discharge electrodes 8 and 9. A high-frequency power source 5, a power supply line 4 connecting the high-voltage high-frequency power source 5 and the discharge electrodes 8 and 9, and a laser gas (CO ₂ ) (not shown) that functions as a laser medium supplied between the discharge electrodes 8 and 9. ). In the three-axis orthogonal pulse CO ₂ laser oscillator, the laser gas flows at a high speed through a long glass tube (not shown) that seals the laser gas.

Further, as described above, the triaxial orthogonal pulse CO ₂ laser has a gas flow direction indicated by an arrow 1, a laser beam 22 indicated by an arrow 2, and a discharge direction indicated by an arrow 3. Each of them is characterized by being orthogonal to each other.

  The discharge electrodes 8 and 9 are respectively installed on opposing surfaces of a pair of dielectric plates 6 and 7 provided to face each other, and are connected to a high-voltage and high-frequency power source 5 through a feeder line 4. When an alternating voltage is applied between the discharge electrodes 8 and 9 by the high-voltage high-frequency power source 5 via the feeder line 4, a uniform discharge is formed between the discharge electrodes 8 and 9 in the direction of the arrow 3. . A laser gas is supplied between the discharge electrodes 8 and 9 in the direction indicated by the arrow 1, that is, the gas flow direction 10, and molecules or atoms in the laser gas obtain energy by the discharge and are excited to the upper level of the laser. When (pumping) is performed, the light amplification effect is exhibited. Then, when the amplified light reciprocates between the total reflection mirror 11 and the partial reflection mirror 12, the light is further amplified by stimulated emission. When this increased energy exceeds the loss energy in the optical resonator, laser oscillation occurs and laser light is emitted. At this time, the partial reflection mirror 12 functions as an output mirror that emits a part of the laser light oscillated from the optical resonator to the outside as a laser beam 22.

Although not shown in FIG. 2, the three-axis orthogonal pulse CO ₂ laser oscillator according to the first embodiment has a structure in which gas is allowed to flow at a high speed through a long glass tube in which the laser gas is sealed. , Square wave and pulse performance is good. Further, the laser beam is excellent in terms of convergence and directivity stability, and the on / off state of the laser beam can be switched instantaneously, so that the running cost is lower than that of a solid-state laser.

Here, since the laser oscillator 21 according to the first embodiment is a pulse laser oscillator, a method for pulsing the laser beam will be described. In general, there are mainly the following three methods for pulsing.
(1) A method by switching using an electro-optic element (EO) or an acousto-optic element (AO).
(2) A method of pulsing a continuously oscillated laser beam by installing a shutter or an acoustooptic device outside the oscillator.
(3) A method of oscillating a laser in a pulsed manner by intermittently generating excitation discharge.

The method (1) is called a Q switch method, and oscillates a pulse by controlling the optical loss (Q value) of the oscillator. The pulse oscillation by the Q switch is mainly used in a solid-state laser, and can oscillate with a short pulse of about several tens of ns and high peak output.
However, the Q switch element used in the Q switch method is expensive because there are few materials that can cope with the infrared region, which is the wavelength of the CO ₂ laser. In addition, even if there is no damage to the element at low output, the thermal lens effect occurs due to the refractive index temperature dependence of the material, resulting in deterioration of processing performance such as changing the beam diameter. Therefore, it cannot be used for fine glass drilling.

In (2) and (3), the repetition frequency of the laser is limited by the frequency of the shutter and excitation discharge.
In the method (2), a continuous wave laser is cut off in time, a high peak output laser cannot be obtained, and it cannot be used for fine glass drilling.
The method (3) is a method of generating a pulse by a gain switch, and the peak output is higher than that of (2). In addition, the pulsed oscillation is performed by intermittently operating the excitation discharge, filling the consumable gas remaining between the discharge electrodes after the single pulse oscillation with a new laser gas, and generating the next pulse in the next excitation discharge. Since only the operation of excitation discharge is performed, the operation method is simple, and it is applied to more pulse CO ₂ lasers than the Q-switch type of (1).

As described above, in the first embodiment, as the laser oscillator 21 for processing the glass microhole, the running cost is low, and the pulse is generated by the gain switch. An orthogonal pulse CO ₂ laser oscillator is used.

The glass 28 to be processed is a brittle material, and there are types such as borosilicate glass, soda glass, alkali glass, and synthetic quartz. In the laser fine hole processing of glass, processing cannot be performed unless the material of the glass to be processed has a light absorption region in the wavelength region of the laser wavelength. In particular, glass 28 that absorbs laser light with respect to the wavelength of the CO ₂ laser to be used is suitable.

The processing conditions for laser micro-hole drilling of glass will be described below.
The thickness of the glass 28 is about 50 to 300 μm, and the hole diameter of the through electrode is about Φ10 to 100 μm.
An example is shown in which a fine hole of about Φ100 μm is processed in a borosilicate glass having a thickness of 150 μm by a gain switch type triaxial orthogonal pulse CO ₂ laser.
Processing conditions are an irradiation beam diameter of Φ100 μm, a repetition frequency of 1 Hz, and an energy density of 15 J / cm ² . Under these processing conditions, continuous irradiation processing was performed by adjusting the pulse width.

  FIG. 3 is a diagram illustrating an example of a processed hole in which a crack has occurred. The pulse width was 10 μs, and a crack 51 surrounding the processed hole 29 occurred around the processed hole 29.

  FIG. 4 is a diagram illustrating an example of a processed hole in which no crack occurs. In FIG. 4, processing was performed under a processing condition with a pulse width of 1 μs, and no cracks occurred in the periphery 52 of the processing hole 29. Cracks can be suppressed by shortening the pulse width.

  The above processing result is an example in which a fine hole of about Φ100 μm is processed in a borosilicate glass having a thickness of 150 μm. On the other hand, the occurrence of cracks was examined based on the results of processing by changing the thickness, material, and hole diameter of the glass 28.

Table 1 is a table showing the presence / absence of crack occurrence at each pulse width (1 μs, 3 μs, 5 μs, 10 μs, 15 μs, 30 μs, 50 μs) by the gain switch type three-axis orthogonal pulse CO ₂ laser oscillator. According to the results in Table 1, no crack was generated when the pulse width was in the range of 1 to 5 μs, and crack was generated when the pulse width was in the range of 10 to 50 μs.

  From the above, as a laser processing condition for forming a fine hole in the glass, the laser beam 22 oscillated from the laser oscillator 21 is set so that the pulse width of the laser beam 22 incident on the laser beam incident surface of the glass 28 is 5 μs or less. The occurrence of cracks can be suppressed by adjusting the pulse width.

  Laser processing conditions include not only the pulse width, but also the irradiation beam diameter, energy density, and repetition frequency. Using these parameters, irradiation is performed without causing large cracks or cracks. Hereinafter, these parameters will be described.

  In order to form a through hole having a diameter of 100 μm or less, the irradiation beam diameter is set to a diameter of 100 μm or less.

FIG. 5 is an example of a result of processing a fine hole in glass at a low energy density by a CO ₂ laser.
In order to form laser microscopic holes in glass, the pulse energy density needs to be ² J / cm ² or more.
When the energy density of the pulse is low, the glass 28 is processed without generating the crack 51, but as shown in FIG. 5, a raised portion 54 and a heat affected layer 53 are generated around the processed hole 29.
Therefore, in order to reduce the heat affected layer 53, it is necessary to process with high energy.
In general, the energy density is increased not only by reducing the irradiation beam diameter but also by increasing the average output. When the through hole is formed, the higher the energy, the higher the taper ratio of the processed hole.
A taper rate shows the ratio of the hole diameter of the back surface with respect to the hole diameter of the glass surface. A taper rate of 100% indicates a case where the diameter of the processed hole on the front surface and the diameter of the processed hole on the back surface are the same.

For the above reasons, in the first embodiment, the pulse energy density is set to ² J / cm ² or more. In the above example, the pulse energy density is set to 15 J / cm ² .

  Further, the repetition frequency is not related to the crack generation conditions, and the higher the productivity, the higher the productivity. In the above example, the repetition frequency is set to 1 Hz.

Since the laser irradiation method irradiates the surface on which the processed hole 29 is to be formed, irradiation may be performed from either the front surface or the back surface of the glass 28 or from both surfaces when forming a through hole.
Further, when the through hole is formed in the glass 28, the rear surface on the irradiation side is processed without contacting the stage base 27.
This is because the glass melt is discharged from the inside of the hole to the outside during the through hole processing, but when the back surface is in contact, it becomes difficult to discharge, and the amount of scattered matter is increased around the processing hole on the back surface. . In addition, heat cannot be discharged and a heat-affected layer or a crack may occur.
For this reason, it is necessary to perform processing in such a manner that the back surface is not in contact with the stage table 27 by a method such as providing a groove.

  Under the above processing conditions, cracks do not occur even in continuous irradiation processing, so there is no need to provide a non-irradiation time, so the processing time can be shortened. In addition, since no cracks are generated, an etching facility is not necessary, and the cost and productivity can be improved.

In addition to the generation of cracks, there is a problem of melt adhesion in the processing quality of processed holes.
In order to remove the melt around the processed hole, there is a method of removing by washing with water in addition to removal with an assist gas. In addition to this, there is a method in which a protective film is formed on the surface to be processed in advance, and the film is removed together with the melt by washing after the processing. The protective film is desirably water-soluble from the viewpoints of film formation simplicity and environmental aspects.

Conventionally, laser micromachining technology for glass has been developed mainly for UV lasers. However, as described above, in this embodiment, there is a track record in the industry and running more than UV lasers. By using a CO ₂ laser oscillator which is excellent in terms of cost and reliability, it is possible to continuously perform fine processing of glass without generation of cracks.

As described above, the first embodiment uses a three-axis orthogonal type pulse CO ₂ laser oscillator that generates a pulse by a gain switch of a three-axis orthogonal type as the laser oscillator 21 in the laser micro-hole drilling of glass. The pulse width was set to 5 μs or less. The triaxial orthogonal CO ₂ laser oscillator has good rectangular wave and pulse performance, is excellent in terms of laser beam convergence and directional stability, and can be switched on and off instantaneously. The running cost is lower than that. Further, in the triaxial orthogonal type, since the cross-sectional area of the gas flow path is large, a high output can be obtained even at a low gas pressure and a low gas flow rate, and the running cost is low. Further, since the pulse is generated by the gain switch, it is possible to process the glass 28 at a high energy density at a time by the laser oscillation of the high peak short pulse, so that it is difficult for extra heat to enter. Further, by setting the pulse width to 5 μs or less, it is possible to perform processing that does not generate the crack 51 around the processing hole 29.

In the first embodiment, the pulse energy density is ² J / cm ² or more. Thereby, it is possible to improve the taper ratio while suppressing the generation of the crack 51, the raised portion 54, and the heat-affected layer 53 around the processed hole 29.

Embodiment 2. FIG.
The entire configuration of the laser processing machine for processing glass fine holes according to the second embodiment of the present invention is basically the same as the configuration shown in FIG. The difference is that in the second embodiment, the laser oscillator 21 is formed of a quantum cascade laser oscillator. Since other configurations and operations are the same as those in the first embodiment, description thereof is omitted here, and different points will be mainly described below.

  A quantum cascade laser (QCL) oscillator is a semiconductor laser using subband transition, and can select a wide range of wavelengths from about 5.0 to 11.0 μm. In addition, the pulse width can be adjusted to less than 5.0 μs, which is suitable for processing conditions for forming glass fine holes without cracks.

However, although the quantum cascade laser oscillator has a high output among the semiconductor laser oscillators, the output is lower than that of the pulse CO ₂ laser oscillator (gas laser) shown in the first embodiment. For this reason, if high output in the wavelength range necessary for laser micro-hole drilling of glass cannot be obtained, it is necessary to amplify by providing amplification means as necessary. As an amplifying means, for example, a method of amplifying by using a discharge-excited CO ₂ laser oscillator gas as an amplifying medium can be considered. Therefore, in the laser fine hole drilling of glass, the wavelength of the laser oscillator 21 needs to be 9.0 to 11.0 μm which is the wavelength range of the pulse CO ₂ laser oscillator. The amplifying unit is installed between the laser oscillator 21 and the beam adjusting optical system 23. The laser light of the quantum cascade laser is used as seed light, and is amplified by using a discharge-excited CO ₂ laser oscillator gas as an amplification medium. As a configuration of the amplifying means, a multipath, an injection lock, or the like can be considered.

Moreover, if the material processed in laser processing does not have an absorption region in the wavelength region of the laser wavelength, it cannot be processed. Therefore, the glass 28 needs to have a light absorption region between 9.0 and 11.0 μm, which is the wavelength range of the pulsed CO ₂ laser oscillator and the quantum cascade laser oscillator. Therefore, the glass 28 made of such a material. To use.

From the above, in the second embodiment, a quantum cascade laser oscillator is used as a laser for processing a fine hole in glass, and, if necessary, an oscillator gas for CO ₂ laser whose discharge is excited is used as an amplification medium. Glass processing is performed by amplifying in the range of 9.0 to 11.0 μm by a method of amplifying and utilizing.

  In addition, as described with reference to FIG. 3, when the pulse width exceeds 5 μs, a crack 51 is generated around the processing hole 29. Therefore, even in the second embodiment, in order to perform processing without the crack 51, a pulse is used. The width needs to be 5 μs or less. Therefore, in the second embodiment, the pulse width of the laser light oscillated from the quantum cascade laser oscillator is adjusted so that the pulse width of the laser beam 22 incident on the laser beam incident surface of the glass 28 is 5 μs or less. I do. When the laser light is amplified by the amplification means, the pulse width is adjusted so that the amplified pulse width is 5 μs or less.

  In the second embodiment, the configuration of the quantum cascade laser oscillator used as the laser oscillator 21 is a general one, and is described in, for example, JP 2010-238711 A.

  The difference between a conventional semiconductor laser oscillator and a quantum cascade laser oscillator will be described. The optical transition in a conventional semiconductor laser is an interband transition between a conduction band level and a valence band level, and light is emitted by recombination of electrons and holes, and laser oscillation is caused by resonance. However, at this time, when an optical transition occurs between levels in the conduction band discretized by the quantum well structure, electrons and holes do not recombine and remain in the conduction band. Further, since interband transition is used, the transition wavelength is determined by the material of the laser medium and cannot be freely selected.

  On the other hand, the quantum cascade laser oscillator has a feature that a transition wavelength can be freely selected by changing the well width because a quantum well is formed and intersubband transition is used. Therefore, the oscillation wavelength can be selected in a wide range. In a quantum cascade laser oscillator, a plurality of quantum wells are stacked with a semiconductor intermediate layer interposed therebetween to create a multiple quantum well. Thus, electrons emitted from one quantum well are guided to adjacent quantum wells by the tunnel effect, where they are caused to make a transition in the conduction band again, just like a multistage waterfall. It has a structure in which one electron performs many transitions one after another. A structure in which quantum wells as light emitting layers are connected in multiple stages is called a cascade structure. Thereby, many light can be emitted from one electron, and high output is possible.

  As explained above, the quantized cascade laser oscillator has the characteristics of intersubband optical transition that allows selection of oscillation wavelength in a wide range and the characteristics of high output by a cascade structure in which light emitting layers are connected in multiple stages. In addition, since it has both, it can be applied to laser micro-hole drilling of glass and a wide range of wavelength selection is possible. Further, by setting the pulse width to 5 μs or less, it is possible to perform processing without cracks. Further, if the output is not sufficient, an amplification means may be provided for amplification.

  As described above, in the second embodiment, since the quantum cascade laser oscillator is used as the laser oscillator 21 in the laser fine hole processing of glass, a wide range of wavelength selection is possible. The wavelength range required for processing can be set freely. In the quantum cascade laser oscillator, since the pulse width can be adjusted to less than 5.0 μs, the pulse width of the laser used for processing the glass microhole is set to be 5 μs or less, so that cracks are generated. Can be suppressed. Under such processing conditions, cracks do not occur even in continuous irradiation processing, so there is no need to provide non-irradiation time. Therefore, it is possible to perform machining continuously, and it is possible to shorten the machining time, so that there is an effect of improving productivity. In addition, since no cracks are generated, an etching facility is not necessary, and cost and productivity can be improved. Thus, also in the second embodiment, the same effect as in the first embodiment described above can be obtained.

In the second embodiment, it is desirable that the pulse energy density is ² J / cm ² or more, as in the first embodiment. When processing is performed in a state where the energy density of the pulse is low, cracks do not occur, but as described above with reference to FIG. 5, the raised portion 54 and the heat-affected layer 53 are generated around the processed hole 29. In order to reduce the generation of the raised portion 54 and the heat-affected layer 53, it is necessary to process with high energy. Therefore, also in the second embodiment, it is desirable that the pulse energy density be ² J / cm ² or more, as in the first embodiment. Further, the taper rate increases as the energy density increases.

  In addition, it is desirable to set other laser processing conditions, that is, the irradiation beam diameter and the repetition frequency in the same manner as in the first embodiment, and perform irradiation without generating large cracks and cracks.

  The configuration of the quantum cascade laser oscillator used in the second embodiment is not limited to the configuration described in Japanese Patent Application Laid-Open No. 2010-238711, and a quantum cascade laser oscillator having an arbitrary configuration is applicable to the present invention. Needless to say, the same effect can be obtained in this case.

  1 arrow (direction of gas flow), 2 arrow (direction of laser beam), 3 arrow (direction of discharge), 4 feeder line, 5 high voltage high frequency power supply, 6, 7 dielectric plate, 8, 9 discharge electrode, 10 Gas flow direction, 11 total reflection mirror, 12 partial reflection mirror (output mirror), 20 stage scanning direction, 21 laser oscillator, 22 laser beam, 23 beam adjustment optical system, 24 light guide mirror, 25 mask, 26 condenser lens, 27 stage base, 28 glass, 29 processed hole, 51 crack, 53 heat-affected layer, 54 raised part.

Claims (5)

A laser processing machine for processing glass microholes for forming microholes in a workpiece made of glass,
A stage base on which the workpiece is mounted;
A laser oscillator for oscillating a laser beam;
A beam adjusting optical system that adjusts the size or beam shape of the laser beam oscillated from the laser oscillator;
A light guide mirror that adjusts the traveling direction of the laser beam after adjustment output from the beam adjustment optical system toward the workpiece mounted on the stage base;
A condensing lens for condensing the laser beam guided by the light guide mirror on a laser beam incident surface of the workpiece,
The laser beam oscillated from the laser oscillator is a CO ₂ laser beam or a laser beam having a wavelength range of 9.0 to 11.0 μm,
The pulse width of the laser beam oscillated from the laser oscillator is adjusted so that the pulse width of the laser beam incident on the laser beam incident surface of the workpiece is 1 to 5 μs. Laser processing machine for processing glass fine holes. The laser processing machine for processing a glass fine hole according to claim 1, wherein the laser oscillator is configured by a three-axis orthogonal pulse CO ₂ laser oscillator that generates a pulse by a gain switch. The said laser oscillator is comprised from the quantum cascade laser. The laser processing machine for glass fine hole processing of Claim 1 characterized by the above-mentioned. Glass micro-drilling laser according to any one of claims 1 to 3 in which pulse energy density of the laser beam oscillated from the laser oscillator is characterized in that it is set to 2J / cm ² or more Processing machine. A glass fine hole processing method for forming a fine hole in a workpiece composed of glass,
Mounting the workpiece on a stage base;
Oscillating a CO ₂ laser beam or a laser beam having a wavelength range of 9.0 to 11.0 μm from a laser oscillator by setting the pulse width to 1 to 5 μs ;
Adjusting the beam diameter or beam shape of the laser beam oscillated from the laser oscillator;
Adjusting the direction of travel of the laser beam after adjustment toward the workpiece mounted on the stage base;
Glass micro-hole processing method characterized by including the step of condensing the light that is led the laser beam to the laser beam incident surface of the workpiece.

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