JP6873283B2 - Optical parts and laser machining machine - Google Patents

Description

The present invention relates to an optical component capable of exhibiting stable optical performance even in a high temperature environment, and a laser processing machine equipped with the optical component.

Conventionally, for example, a laser processing machine has been used for drilling a printed wiring board built in an electronic device such as a smartphone or a tablet PC. The laser used in the laser processing machine is mainly an infrared CO ₂ laser having an oscillation wavelength of 9 to 11 μm. The CO ₂ laser is capable of high-power oscillation and has a high absorption rate into resin.

In the laser processing machine for drilling, a condenser lens is arranged above the processing area. Therefore, the condenser lens may be damaged or deteriorated due to dust and sputtering generated during drilling. Therefore, by arranging an optical component called a protective window between the workpiece and the condenser lens, damage and deterioration of the condenser lens are prevented.

Dust and sputtering generated during drilling are likely to adhere to the protective window. Further, dust and sputtering deposited on CO ₂ laser on the optical path, since the temperature rises and absorbs the CO ₂ laser, the protective window becomes hot. Therefore, the protective window is required to have transparency and environmental resistance to _{a CO 2 laser which is infrared light.} Environmental resistance refers to wear resistance that does not damage the surface even when the adhered resin spatter or copper spatter is wiped off, and heat resistance that exhibits stable optical performance even when exposed to a high temperature environment. Point to.

For example, as an optical component used for an infrared sensor or the like and having excellent coating abrasion resistance and infrared transmittance, the first Y ₂ O is placed on the surface side of a ZnS (zinc sulfide) substrate in order from the substrate surface. _{A multilayer film in which a 3} (yttrium oxide) layer, a YF ₃ (yttrium fluoride) layer, a second Y ₂ O ₃ (yttrium oxide) layer, a Ge (germanium) layer, and a DLC (diamond-like carbon) layer are laminated is formed. Things are known. Since the DLC layer forming the multilayer film has compressive stress, a load is applied to the entire multilayer film, and the film may peel off at the interface having low adhesion in the multilayer film. Therefore, in such an optical component, a Ge layer is formed as an adhesion layer of the DLC layer, _{and a Y 2} O ₃ layer made of an oxide is _{further formed as an adhesion layer of the YF 3} layer to ensure the adhesion of the multilayer film. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-268277

However, the optical components described in Patent Document 1 do not take heat resistance into consideration. Therefore, due to the influence of heat, the YF ₃ layer and the Y ₂ O ₃ layer in the multilayer film cause atomic mutual diffusion at the interface, and the film is denatured. Therefore, when the optical component described in Patent Document 1 is used as a protective window of a laser processing machine exposed to a high temperature environment, there is a problem that stable optical characteristics cannot be obtained.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain an optical component capable of stably exhibiting optical performance even in a high temperature environment.

The optical component according to the present invention comprises a substrate having a main surface and a second surface formed on the back side of the main surface, and a multilayer film formed on at least the main surface of the main surface and the second surface. The substrate is formed to contain Ge (germanium), and the multilayer film includes a film in which an oxide film, a fluoride amorphous film, a Ge film and a DLC film are laminated in this order from the side closer to the substrate. ..

The present invention improves the heat resistance of optical components by having a layer in which an oxide film, a fluoride amorphous film, a Ge film and a DLC film are laminated on the surface of a substrate containing Ge in this order from the side closer to the substrate. Can be made to. As a result, it is possible to provide an optical component that exhibits stable optical performance without deteriorating the optical characteristics due to the influence of heat.

It is a schematic diagram of the laser processing machine which mounted the optical component according to Embodiment 1 of this invention. It is a schematic diagram which shows the cross section of the optical component of Embodiment 1. FIG. It is a figure which shows the modification of the optical component by Embodiment 1. FIG. It is a schematic diagram which shows the cross section of the optical component of Embodiment 2 of this invention.

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

Embodiment 1.
FIG. 1 is a schematic view of a laser processing machine 1 equipped with a protective window 15 as an optical component according to the first embodiment of the present invention. FIG. 2 is a schematic view showing a cross section of the protective window 15 of FIG.

As shown in FIG. 1, the laser processing machine 1 includes a laser oscillator 11, a condenser lens 13, and a protective window 15. _{A CO 2} laser is used in the laser oscillator 11. The oscillation wavelength of this CO ₂ laser is 9.3 μm. The laser beam 11A emitted from the laser oscillator 11 is focused by the condenser lens 13, passes through the protective window 15, and is imaged on the surface of the workpiece 100 such as a printed wiring board. Then, the work piece 100 is drilled or the like by the laser beam 11A.

Many of the optical materials of the condensing system of a laser processing machine using a _{CO 2 laser have a relatively high refractive index.} Therefore, the condenser lens 13 is arranged at a position close to the workpiece 100. Further, the protective window 15 is arranged between the condensing lens 13 and the workpiece 100 in order to protect the condensing lens 13 from dust and spatter generated during the drilling process. Therefore, the protective window 15 is arranged at a position where the distance from the workpiece 100 is about 100 mm. Therefore, the protective window 15 is exposed to a harsh environment of a large amount of dust and spatter during laser processing. Since the dust and spatter adhering to the protective window 15 absorb the laser beam 11A and generate heat, the protective window 15 is required to have heat resistance in addition to the transparency of the laser beam 11A.

As shown in FIG. 2, the protective window 15 has a substrate 150 having a main surface 150A formed on one surface and a second surface 150B formed on the back surface side of the main surface 150A. The main surface 150A is a surface on the processing space side facing the workpiece 100, and the second surface 150B is a surface facing the condenser lens 13.

Conventionally, ZnS (zinc sulfide) has been mainly used as a substrate for optical components, but the protective window 15 of the first embodiment is Ge (germanium) which can obtain an infrared laser light transmittance higher than that of ZnS. The substrate 150 is formed by. Further, since ZnS has a low thermal conductivity, a large temperature gradient is generated on the substrate when the laser processing is continuously performed. The temperature gradient generated on this substrate causes the optical component to have a refractive index distribution. Then, a phenomenon called a thermal lens effect occurs in the optical component, and the accuracy of laser processing is lowered. Therefore, ZnS is not suitable as a material for the substrate 150 of the protective window 15 of the laser processing machine 1. Ge forming the substrate 150 has a higher thermal conductivity than ZnS. In addition to Ge, other elements other than Ge may be added to the material of the substrate 150.

A multilayer film 2 is formed on each of the main surface 150A and the second surface 150B of the substrate 150. The protective window 15 is arranged with the main surface 150A of the substrate 150 facing the work piece 100 side.

The multilayer film 2 includes a film in which four layers of an oxide film 21, a fluoride amorphous film 22, a Ge film 23, and a DLC film 24 are laminated in this order from the side closer to the substrate 150. These films may be formed by covering the main surface 150A and the second surface 150B over the entire surface so that the base material 150 is not exposed, or covering a part of the surface so that a part of the base material is exposed. It may be formed.

Examples of the material for forming the oxide film 21 include Y ₂ O ₃ (yttrium oxide), HfO ₂ (hafnium oxide), ZrO ₂ (zinc oxide), Ta ₂ O ₃ (tantal oxide), and TIO ₂ (titanium oxide). , SiO (silicon oxide), Al ₂ O ₃ (aluminum oxide) and the like. When an infrared CO ₂ laser is used, it is preferable to use any one of _{Y 2} O ₃ , HfO ₂ , and ZrO ₂ , which has excellent infrared light transmission. The film thickness of the oxide film 21 is preferably 5 nm or more in order to ensure the adhesion of the film. The film thickness of the oxide film 21 is preferably 150 nm or less in order to ensure the transparency of infrared light.

Examples of the material for forming the fluoride amorphous film 22 include YF ₃ (yttrium fluoride), YbF ₃ (ytterbium fluoride), MgF ₂ (magnesium fluoride), BaF ₂ (barium fluoride), and CaF ₂ (fluoride fluoride). Fluoride such as calcium) can be mentioned. When _{using an infrared CO 2} laser, it is preferable to use any one of _{YF 3} , YbF ₃ or MgF ₂ , which has excellent infrared light transmission. The film thickness of the fluoride amorphous film 22 is preferably 500 nm to 950 nm in order to ensure the transparency of infrared light.

The Ge film 23 has good adhesion to the DLC film 24. Therefore, by forming the Ge film 23, the adhesion of the DLC film 24 to the substrate 150 can be ensured. The film thickness of the Ge film 23 is preferably 50 nm to 150 nm in order to satisfy both the adhesion of the film and the transmission of infrared light.

The DLC film 24 has a high hardness. Therefore, it has excellent wear resistance when wiping off dirt adhering to the film. Further, the DLC film 24 has high stability as a substance and does not easily react with other materials. Therefore, dust, metal spatter, and the like generated during the drilling process of the printed circuit board and the like are less likely to adhere to the DLC film 24. Therefore, by forming the DLC film 24, it is possible to suppress the adhesion of dirt to the protective window 15. Further, by forming the DLC film 24, the dirt adhering to the protective window 15 can be easily removed. The film thickness of the DLC film 24 is preferably 50 nm or more in order to ensure wear resistance. The film thickness of the DLC film 24 is preferably 300 nm or less in order to ensure the transparency of infrared light.

Further, the oxide film 21 has excellent adhesion to the Ge-made substrate 150 and the fluoride amorphous film 22. Therefore, the oxide film 21 can ensure the adhesion between the fluoride amorphous film 22 and the substrate 150. As long as the permeability and heat resistance of the multilayer film 2 are not lowered, there is no problem even if other elements are added to these four layers. Further, as long as the permeability and heat resistance of the multilayer film 2 are not lowered, there is no problem even if another thin film is formed in addition to these four layers.

As described above, the protective window 15 of the first embodiment has four layers of an oxide film 21, a fluoride amorphous film 22, a Ge film 23, and a DLC film 24 laminated on the surface thereof in order from the side closer to the substrate 150. The multilayer film 2 is provided. Then, a fluoride amorphous film 22 which is made amorphous by controlling the structure of fluoride is arranged between the oxide film 21 and the Ge film 23. Then, the high-speed diffusion path such as the crystal grain boundary of fluoride is eliminated, and the mutual diffusion of atoms between the oxide film 21 and the fluoride amorphous film 22 is suppressed. As a result, even if the protective window 15 becomes hot during laser processing, the film quality of the multilayer film 2 does not change due to atomic diffusion. Therefore, the protective window 15 can exhibit stable optical performance.

In the first embodiment, the multilayer film 2 is formed on both the main surface 150A and the second surface 150B of the substrate 150 of the protective window 15, but the multilayer film 2 is formed on the second surface 150B of the substrate 150. It does not have to be formed. For example, as in the protective window 15A of the first modification shown in FIG. 3, the multilayer film 2 is formed on the main surface 150A of the substrate 150, and the antireflection film 30 different from the multilayer film 2 is formed on the second surface 150B. May be formed.

Next, a protective window 15 which is an optical component of the first embodiment and a conventional optical component as Comparative Example 1 are created, and the results of comparing their respective characteristics will be described.

As a method of forming a film on the surface of the substrate of an optical component, a PVD method (physical vapor deposition method) represented by a vacuum deposition method and a sputtering method, or a CVD method (chemical vapor deposition) represented by a plasma CVD method is used. There are generally known film forming methods such as phase growth method). However, any method may be used as long as it can form a film on the substrate.

First, the protective window 15 of the first embodiment will be described. The substrate 150 of the protective window 15 was formed of Ge. The shape of the substrate 150 was a disk shape having a diameter of 120 mm and a thickness of 5 mm. Then, the multilayer film 2 was formed on the main surface 150A of the substrate 150. Of the multilayer film 2, Y ₂ O ₃ was used as the oxide film 21. Further, among the multilayer films 2, YF ₃ was used for the fluoride amorphous film 22.

_{Then, on the main surface 150A of the substrate 150, the oxide film 21 (Y 2} O ₃ : film thickness 50 nm) and the fluoride amorphous film 22 (YF ₃ : film thickness 570 nm) are arranged in this order from the side closer to the main surface 150A of the substrate 150. , Ge film 23 (thickness 120 nm) and DLC film 24 (thickness 150 nm) were laminated to form a multilayer film 2.

On the other hand, on the second surface 150B of the substrate 150, an antireflection film 30 having a transmittance of 99% or more at a wavelength of 9.3 μm was formed. _{The antireflection film 30 has a structure in which a YF 3} film (film thickness 670 nm), a Ge film (film thickness 130 nm), and an MgF ₂ film (film thickness 200 nm) are laminated in this order from the side closer to the second surface 150B of the substrate 150. And said. The configuration of the antireflection film 30 is not limited to this.

The fluoride amorphous film 22, the Ge film 23, and the antireflection film 30 were formed by a vacuum vapor deposition method. Further, the DLC film 24 was formed by using a sputtering method.

Generally, when the film formation temperature is raised and the film material is slowly cooled on the substrate, the structure becomes crystalline. On the other hand, when the film formation temperature is lowered and the film material is rapidly cooled on the substrate, it becomes an amorphous amorphous substance having no crystal structure. In the formation of the fluoride amorphous film 22, _{the film formation temperature of YF 3} in the vacuum vapor deposition method was set to 150 ° C. in order to make the structure of _{YF 3 amorphous.}

Next, the optical component of Comparative Example 1 will be described. The optical component of Comparative Example 1 is different from the protective window 15 of the first embodiment in that _{the YF 3} of the fluoride amorphous film 22 constituting the multilayer film 2 is made crystalline instead of amorphous. Other configurations are the same as those of the protective window 15 of the first embodiment. In the optical component of Comparative Example 1, to the crystalline structure of YF _3, it was set the deposition temperature of YF ₃ in the vacuum evaporation method 210 ° C..

As described above, the multilayer film formed on the main surface of the substrate of the optical component of Comparative Example 1 is an oxide film (Y ₂ O ₃ : film thickness 50 nm) and a fluoride crystal film in order from the side closer to the main surface of the substrate. (YF ₃ : film thickness 570 nm), Ge film (film thickness 120 nm), and DLC film (film thickness 150 nm) were laminated. On the other hand, an antireflection film 30 similar to the protective window 15 of the first embodiment was formed on the second surface of the substrate of the optical component of Comparative Example 1.

Next, for the protective window 15 of the first embodiment and the optical component of the comparative example 1, _{the structure of the YF 3} on the main surface was analyzed and the infrared absorption rate was calculated.

XRD analysis was used for structural analysis. Then, as a result of the XRD analysis, _{the one in which the diffraction peak caused by the YF 3} crystal appeared was defined as crystalline, and the one in which _{the diffraction peak caused by the YF 3} crystal did not appear was designated as amorphous amorphous.

The transmittance and reflectance of the laser beam having a wavelength of λ = 9.3 μm were used to calculate the infrared absorptivity. A Fourier transform infrared spectrophotometer was used to measure the transmittance and reflectance of the laser light.

Infrared absorptivity is based on the transmittance and reflectance of laser light measured using a Fourier transform infrared spectrophotometer.
(Infrared absorption rate) = 100%-(Transmittance)-(Reflectance)
It was calculated by the formula of. The infrared absorption rate was calculated twice, before and after the heat treatment was performed on the protective window 15 of the first embodiment and the optical component of the comparative example 1. The conditions for the heat treatment were 12 hours in the air at 200 ° C.

_{Table 1 shows the analysis result of the structure of YF 3 on} the main surface and the calculation result of the infrared absorption rate in the protective window 15 of the first embodiment and the optical component of the comparative example 1.

As shown in the XRD analysis results of Table 1, the protective window 15 of the first embodiment has an amorphous structure of _{YF 3.} On the other hand, in the optical component of Comparative Example 1, the structure of _{YF 3 is crystalline.}

Further, from Table 1, the calculation result of the infrared absorption rate of the protective window 15 of the first embodiment was 2.2% before the heat treatment and 2.1% after the heat treatment. On the other hand, the calculation result of the infrared absorption rate of the optical component of Comparative Example 1 was 2.8% before the heat treatment and 4.1% after the heat treatment.

As the protective window of the laser processing machine, it is desirable that the infrared absorption rate is 3.0% or less, and the lower it is, the more preferable. Since the protective window 15 of the first embodiment has an infrared absorption rate of less than 3.0% before and after the heat treatment, it has sufficient optical performance as the protective window 15 of the laser processing machine 1. Further, the protective window 15 of the first embodiment has about half the infrared absorption rate after the heat treatment as compared with the comparative example 1 which is a conventional optical component. From the above results, it was confirmed that the protective window 15 of the first embodiment has improved heat resistance as compared with the conventional optical component.

As described above, according to the protective window 15 of the first embodiment, the oxide film 21, the fluoride amorphous film 22, and the Ge film 23 are arranged in this order from the side closer to the main surface 150A of the substrate 150, with Ge as the substrate 150. And the DLC film 24 is formed. As a result, the protective window 15 of the first embodiment has high transmittance, heat resistance, and abrasion resistance. Therefore, the protective window 15 of the first embodiment can reduce the loss of the laser beam of the laser processing machine. Further, the protective window 15 of the first embodiment can exhibit stable optical performance even when exposed to high heat during laser machining.

Embodiment 2.
Next, the protective window 15B of the second embodiment will be described with reference to FIG. The protective window 15B of the second embodiment is different from the protective window 15 of the first embodiment in the configuration of the multilayer film 2B formed on the main surface 150A of the substrate 150. Other configurations are the same as those in the first embodiment.

The multilayer film 2 of the first embodiment is formed including a film in which four layers of an oxide film 21, a fluoride amorphous film 22, a Ge film 23, and a DLC film 24 are laminated in this order from the side closer to the substrate 150. It was. On the other hand, in the multilayer film 2B of the second embodiment, as shown in FIG. 4, the oxide film 21, the fluoride amorphous film 22, the second oxide film 25, the Ge film 23, and the like, are arranged in this order from the side closer to the substrate 150. It is formed to include a film in which five layers of the DLC film 24 are laminated.

The second oxide film 25 has an effect of suppressing peeling of the multilayer film 2B by bringing the fluoride amorphous film 22 and the Ge film 23, which are the weakest interfaces of the multilayer film 2B, into close contact with each other.

In the protective window 15B shown in FIG. 4, a multilayer film 2B is formed on the main surface 150A of the substrate 150, and an antireflection film 30 different from the multilayer film 2B is formed on the second surface 150B. The multilayer film 2B formed on the main surface 150A of the substrate 150 is, for example, an oxide film 21 (Y ₂ O ₃ : film thickness 25 nm) and a fluoride amorphous film 22 (in order from the side closer to the main surface 150A of the substrate 150). It is formed by laminating YF ₃ : a second oxide film 25 (Y ₂ O ₃ : film thickness 25 nm), Ge film 23 (thickness 120 nm), and DLC film 24 (thickness 150 nm).

On the other hand, an antireflection film 30 having a transmittance of 99% or more at a wavelength of 9.3 μm is formed on the second surface 150B of the substrate 150. _{In the antireflection film 30, a YF 3} film (thickness 670 nm), a Ge film (thickness 130 nm), and an MgF ₂ film (thickness 200 nm) are laminated in this order from the side closer to the second surface 150B of the substrate 150. It was configured. The configuration of the antireflection film 30 is not limited to this.

Here, other elements may be added to the layers constituting the multilayer film 2B as long as there is no effect of deteriorating the optical performance and mechanical properties of the multilayer film 2B. Further, other thin films may be formed in addition to the layers constituting the multilayer film 2B as long as there is no effect of deteriorating the optical performance and mechanical properties of the multilayer film 2B. Further, the oxide film 21 and the second oxide film 25 may be a film using the same oxide or a film using different types of oxides.

As described above, the multilayer film 2B of the second embodiment has five layers of an oxide film 21, a fluoride amorphous film 22, a second oxide film 25, a Ge film 23, and a DLC film 24 in this order from the side closer to the substrate 150. It is formed to include a laminated film. As a result, the protective window 15B of the second embodiment has excellent heat resistance and can stably exhibit optical performance even in a high temperature environment.

Further, the protective window 15B of the second embodiment has a second oxide film 25 between the fluoride amorphous film 22 and the Ge film 23, so that the fluoride amorphous film 22 and the Ge film 23 are in close contact with each other. Therefore, the peeling of the multilayer film 2B can be suppressed.

1 Laser processing machine, 11 Laser oscillator, 11A laser light, 13 Condensing lens, 15, 15A, 15B protective window (optical component), 2,2B multilayer film, 21 oxide film, 22 fluoride amorphous film, 23 Ge film , 24 DLC film, 25 second oxide film, 30 antireflection film, 100 workpiece, 150 substrate, 150A main surface, 150B second surface.

Claims (6)

A substrate having a main surface and a second surface formed on the back side of the main surface,
An optical component having a multilayer film formed on at least the main surface of the main surface and the second surface.
The substrate is formed including Ge, and is formed.
The multilayer film, in order from a side closer to the substrate, oxide film, seen including a film in which at least four layers are stacked fluoride amorphous film, Ge film and DLC film
An optical component in which the oxide film and the fluoride amorphous film are adjacent to each other. The oxide film is formed by containing any one of _{Y 2} O ₃ , HfO ₂ and ZrO _2.
The fluoride amorphous film is formed containing any one of _{YF 3} , YbF ₃ and MgF _2.
The optical component according to claim 1. The oxide film has a thickness of 5 to 150 nm and has a thickness of 5 to 150 nm.
The fluoride amorphous film has a thickness of 500 to 950 nm and has a thickness of 500 to 950 nm.
The Ge film has a thickness of 50 to 150 nm and has a thickness of 50 to 150 nm.
The DLC film has a thickness of 50 to 300 nm.
The optical component according to claim 2. A second oxide film is provided between the fluoride amorphous film and the Ge film.
The second oxide film is formed containing any one of _{Y 2} O ₃ , HfO ₂ and ZrO _2.
The optical component according to claim 3. The optical component according to claim 4, wherein the second oxide film has a thickness of 5 to 150 nm. A laser processing machine having a laser oscillator and an optical system of laser light emitted from the laser oscillator.
The optical system includes the optical component according to claim 3 or 5.
The optical component is a laser processing machine in which the main surface is arranged so as to face the processing space side.

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