TWI739060B - Optical parts and laser processing machine - Google Patents

Abstract

An objective of this invention is to obtain an optical parts capable of exhibiting stable optical performance even in a high temperature environment.

This invention provides an optical parts including 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 out of the main surface and the second surface, wherein the substrate is formed to contain at least Ge, and the multilayer film contains a film in which at least four layers of 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.

Description

Optical parts and laser processing machines

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 perforating a printed wiring board embedded in an electronic device represented by a smartphone or a tablet PC. The laser used in the laser processing machine is mainly a CO ₂ laser with an infrared light with an oscillation wavelength of 9 to 11 μm. The CO ₂ laser system can oscillate with high output power and has a high absorption rate in the resin.

The condensing lens of the laser processing machine for perforation processing is arranged above the processing area. Therefore, the condensing lens may be damaged or deteriorated due to dust and splashes generated during the piercing process. Therefore, an optical component called a protective window is arranged between the workpiece and the condenser lens to prevent damage and deterioration of the condenser lens.

Dust and splashes generated during perforation are easy to adhere to the protective window. Further, because the dust adhering to the optical path of the CO ₂ laser and the material will splash CO ₂ absorption transition laser temperature rises, the protective window becomes a high temperature. Therefore, the protective window is required to have _{transmittance to infrared CO 2} lasers and environmental resistance. The so-called environmental resistance refers to the abrasion resistance that does not cause damage to the surface even if the attached resin splash or copper shot is wiped off; and it can exhibit stable optical performance even when exposed to a high temperature environment. Heat resistance.

For example, as an optical component with excellent coating wear resistance and infrared transmittance used in infrared sensors, etc., there is a known one on the surface side of a ZnS (zinc sulfide) substrate. 1Y ₂ O ₃ (yttrium oxide) layer, YF ₃ (yttrium fluoride) layer, second Y ₂ O ₃ (yttrium oxide) layer, Ge (germanium) layer, DLC (diamond-like carbon) layered to form a multilayer film . Since the DLC layer forming the multilayer film has compressive stress, the entire multilayer film bears a load and there is a possibility of film peeling at the interface of the multilayer film with low adhesion. Therefore, in such optical parts, the Ge layer is formed as the adhesion layer of the DLC layer, and the Y ₂ O ₃ layer formed of oxide is formed as the adhesion layer of the YF ₃ layer to ensure the adhesion of the multilayer film ( For example, refer to Patent Document 1).

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2008-268277 A

However, the optical component system described in Patent Document 1 does not consider heat resistance. Therefore, due to the influence of heat, inter-diffusion of atoms occurs at the interface _{between the YF 3} layer and the Y ₂ O _{3 layer in the multilayer film, and the film is deteriorated.} 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 was developed to solve the above-mentioned problems, and its purpose is to obtain an optical component that can exhibit stable optical performance even in a high-temperature environment.

The optical component of the present invention has 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 among the main surface and the second surface, wherein the substrate contains Ge (Germanium), and the multilayer film includes a film in which at least four layers of an oxide film, a fluoride amorphous film, a Ge film, and a DLC film are sequentially stacked from the side close to the substrate.

The present invention can improve the heat resistance of optical parts by having layers on the surface of a substrate containing Ge that are sequentially laminated with an oxide film, a fluoride amorphous film, a Ge film, and a DLC film from the side close to the substrate. sex. Thereby, it is possible to provide an optical component whose optical characteristics are not deteriorated due to the influence of heat and can exhibit stable optical performance.

1‧‧‧Laser processing machine

11‧‧‧Laser oscillator

11A‧‧‧Laser light

13‧‧‧Condenser lens

15, 15A, 15B‧‧‧Protection window (optical parts)

2. 2B‧‧‧Multilayer film

21‧‧‧Oxide film

22‧‧‧Fluoride amorphous film

23‧‧‧Ge film

24‧‧‧DLC film

25‧‧‧Second oxide film

30‧‧‧Anti-reflective film

100‧‧‧Processed object

150‧‧‧Substrate

150A‧‧‧Main side

150B‧‧‧Second side

Fig. 1 is a schematic diagram of a laser processing machine equipped with an optical component according to Embodiment 1 of the present invention.

Figure 2 is a schematic diagram showing a cross-section of the optical component of the first embodiment.

Fig. 3 is a diagram showing a modification of the optical component according to the first embodiment.

Fig. 4 is a schematic diagram showing a cross-section of an optical component according to Embodiment 2 of the present invention.

Hereinafter, a preferred embodiment of the optical component of the present invention will be explained using drawings.

Implementation mode 1.

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

As shown in FIG. 1, the laser processing machine 1 has a laser oscillator 11, a condenser lens 13, and a protection window 15. The laser oscillator 11 uses a CO ₂ laser. The CO ₂ laser has an oscillation wavelength of 9.3 μm. The laser light 11A irradiated from the laser oscillator 11 is collected by the condenser lens 13 and transmitted through the protective window 15 to form an image on the surface of the workpiece 100 such as a printed wiring board. Then, the workpiece 100 is subjected to perforation processing or the like by the laser beam 11A.

Most of the optical materials of the condenser system of the laser processing machine using CO _{2 lasers have a higher refractive index.} Therefore, the condenser lens 13 is arranged at a position close to the workpiece 100. In addition, the protective window 15 is arranged between the condenser lens 13 and the workpiece 100 to protect the condenser lens 13 from dust and splashes generated during the perforation process. Therefore, the protective window 15 is arrange|positioned at the position which the distance from the to-be-processed object 100 is about 100 mm. Therefore, the protective window 15 is exposed to a harsh environment with a large amount of dust and splashes during laser processing. Because the dust and splashes attached to the protective window 15 absorb the laser light 11A and generate heat, the protective window 1 is required to have heat resistance in addition to the transmittance of the laser light 11A.

As shown in FIG. 2, the protective window 15 has a substrate 150 having a main surface 150A formed on one side and a second surface 150B formed on the back side of the main surface 150A. The main surface 150A is a surface facing the processing space side of 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. However, in order to obtain a higher infrared laser light transmittance than ZnS, the protective window 15 of the first embodiment uses Ge (germanium) to form the substrate 150. In addition, because ZnS has a low thermal conductivity, a large temperature gradient is generated on the substrate during continuous laser processing. Due to the temperature gradient generated on the substrate, the refractive index distribution of the optical component is generated. As a result, a phenomenon called thermal lens effect occurs in optical parts and the accuracy of laser processing is low. Therefore, ZnS is not suitable as a laser processing machine 1 is the material of the substrate 150 of the protective window 15. The thermal conductivity of Ge forming the substrate 150 is higher than that of ZnS. Furthermore, elements other than Ge may be added to the material of the substrate 150 together with Ge.

The main surface 150A and the second surface 150B of the substrate 150 are each formed with a multilayer film 2. Then, the protective window 15 is arranged so that the main surface 150A of the substrate 150 faces the side of the workpiece 100.

The multilayer film 2 includes four layers of an oxide film 21, a fluoride amorphous film 22, a Ge film 23, and a DLC film 24 in this order from the side close to the substrate 150.

Examples of materials for forming the oxide film 21 include Y ₂ O ₃ (yttrium oxide), HfO ₂ (hafnium oxide), ZrO ₂ (zirconium oxide), Ta ₂ O ₃ (tantalum oxide), TiO ₂ (titanium oxide) ), SiO ₂ (silicon _{oxide), Al 2} O ₃ (alumina), etc. When infrared CO ₂ lasers are used, it is preferable to use any of Y ₂ O ₃ , HfO ₂ , and ZrO ₂ having excellent infrared light transmittance. In order to ensure the adhesion of the film, the thickness of the oxide film 21 is preferably 5 nm or more. In addition, in order to ensure infrared light transmittance, the film thickness of the oxide film 21 is preferably 150 nm or less.

As a material for forming the fluoride amorphous film 22, for example, YF ₃ (yttrium fluoride), YbF ₃ (ytterbium fluoride), MgF ₂ (magnesium fluoride), BaF ₂ (barium fluoride), CaF ₂ ( Fluoride such as calcium fluoride). When infrared CO ₂ lasers are used, it is better to use any of YF ₃ , YbF ₃ or MgF ₂ with excellent infrared light transmittance. In order to ensure infrared light transmittance, the film thickness of the fluoride amorphous film 22 is preferably 500 nm to 950 nm.

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. In order to satisfy both the adhesiveness of the film and the infrared light transmittance, the film thickness of the Ge film 23 is preferably 50 nm to 150 nm.

The hardness of the DLC film 24 is relatively high. Therefore, when wiping off the contamination attached to the membrane Has excellent wear resistance. In addition, the material stability of the DLC film 24 is relatively high and it is difficult to react with other materials. Therefore, dust and metal splashes generated during perforation processing of a printed circuit board or the like do not easily adhere to the DLC film 24. Therefore, by forming the DLC film 24, it is possible to suppress adhesion of contamination to the protective window 15. In addition, by forming the DLC film 24, the contamination adhering to the protective window 15 can be easily removed. In order to ensure abrasion resistance, the film thickness of the DLC film 24 is preferably 50 nm or more. In addition, in order to ensure infrared light transmittance, the thickness of the DLC film 24 is preferably 300 nm or less.

In addition, the oxide film 21 has excellent adhesion to the Ge 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. In addition, when the transmittance and heat resistance of the multilayer film 2 are not reduced, there is no problem in adding other elements to the 4 layers of the film. Moreover, if the transmittance and heat resistance of the multilayer film 2 are not reduced, there is no problem even if other thin films are formed in addition to the 4 layers of these films.

In this way, the protective window 15 of the first embodiment is provided with four layers in which an oxide film 21, a fluoride amorphous film 22, a Ge film 23, and a DLC film 24 are sequentially stacked on the surface from the side close to the substrate 150. Multilayer film 2. Furthermore, between the oxide film 21 and the Ge film 23, a fluoride amorphous film 22 is arranged to control the structure of the fluoride to become amorphous. Then, the high-speed diffusion path such as the crystal grain boundary of the fluoride is eliminated, and the occurrence of interdiffusion of atoms between the oxide film 21 and the fluoride amorphous film 22 is suppressed. Thereby, even if the protective window 15 becomes a high temperature during laser processing, the multilayer film 2 does not change the film quality due to atom diffusion. Therefore, the protective window 15 can exhibit stable optical performance.

In addition, 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 protection window 15, but the second surface 150B of the substrate 150 is also formed The multilayer film 2 may not be formed. For example, in the protective window 15A of the first modification shown in FIG. 3, the multilayer film 2 may be formed on the main surface 150A of the substrate 150, and the anti-reflection film 30 different from the multilayer film 2 may be formed on the second surface 150B.

Next, the protective window 15 of the optical component of Embodiment 1 and the conventional optical component as Comparative Example 1 are manufactured, and the result of comparing the characteristics of each will be described.

As a method of forming a film on the surface of an optical component substrate, there are generally known PVD method (physical vapor growth method) represented by the vacuum evaporation method and sputtering method, or the CVD method represented by the plasma CVD method ( Chemical vapor growth method) of the film forming method. However, any method can be used as long as it can form a film on the substrate.

First, the protective window 15 of Embodiment 1 will be described. The substrate 150 of the protection window 15 is formed of Ge. The shape of the substrate 150 is a circular plate with a diameter of 120 mm and a thickness of 5 mm. Then, the multilayer film 2 is formed on the main surface 150A of the substrate 150. In the multilayer film 2, Y ₂ O ₃ is used for the oxide film 21. Further, among 2, a fluoride-based amorphous film 22 using the multilayer film YF _3.

Then, on the main surface 150A of the substrate 150, an oxide film 21 (Y ₂ O ₃ : film thickness 50 nm) and a fluoride amorphous film 22 (YF ₃ : A multilayer film 2 consisting of a film thickness of 570 nm), a Ge film 23 (film thickness of 120 nm), and a DLC film 24 (film thickness of 150 nm).

On the other hand, the second surface 150B of the substrate 150 is formed with an anti-reflection film 30 having a transmittance of 99% or more at a wavelength of 9.3 μm. The anti-reflection film 30 is formed by sequentially layering YF ₃ film (film thickness 670nm), Ge film (film thickness 130nm), and MgF ₂ film (film thickness 200nm) from the side close to the second surface 150B of the substrate 150 The composition. In addition, the structure of the anti-reflection film 30 is not limited to this.

The fluoride amorphous film 22, the Ge film 23 and the anti-reflection film 30 are vacuum evaporated The law is formed. In addition, the DLC film 24 is formed using the sputtering method.

Generally, when the film forming temperature is increased and the film material is slowly cooled on the substrate, its structure becomes crystalline. On the other hand, when the film forming temperature is lowered and the film material is rapidly cooled on the substrate, it becomes an amorphous film that does not have a crystalline structure. When forming the fluoride amorphous film 22, in order to make _{the structure of the YF 3 amorphous, the film formation temperature of the YF 3} in the vacuum vapor deposition method is set to 150°C.

Next, the optical component of Comparative Example 1 will be described. The optical component of Comparative Example 1 differs from the protective window 15 of the first embodiment _{in that YF 3} of the fluoride amorphous film 22 constituting the multilayer film 2 is not amorphous but crystalline. The other structure is the same as that of the protective window 15 of the first embodiment. In the optical component of Comparative Example 1, in order to make _{the structure of YF 3 crystalline, the film forming temperature of YF 3} in the vacuum vapor deposition method was set to 210°C.

From the 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 of 50 nm) and a fluoride crystal film on the side close to the main surface of the substrate. (YF ₃ : Film thickness 570nm), Ge film (film thickness 120nm), DLC film (film thickness 150nm) laminated structure. On the other hand, the second surface of the substrate of the optical component of Comparative Example 1 is formed with the same anti-reflection film 30 as the protective window 15 of the first embodiment.

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

The analysis system of the structure uses XRD (X-Ray Diffractometer; X-Ray Diffractometer) analysis. In addition, as a result of XRD analysis, a _{substance that exhibits a diffraction peak due to the crystal of YF 3} was evaluated as crystalline, and a substance that did not show a _{diffraction spike due to the crystal of YF 3} was evaluated as an amorphous substance.

The infrared absorption rate is calculated using the transmittance and reflectance of laser light with a wavelength of λ=9.3μm. In addition, the transmittance and reflectance of the laser light were measured using a Fourier transform infrared spectrophotometer.

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

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

As shown by the XRD analysis results in Table 1, the structure _{of YF 3 of the protective window 15 of Embodiment 1 is amorphous. In contrast, the structure of YF 3} of the optical component of Comparative Example 1 is crystalline.

In addition, from Table 1, the calculation result of the infrared absorption rate of the protective window 15 of Embodiment 1 is 2.2% before the heat treatment and 2.1% after the heat treatment. In contrast, the comparative example 1 The calculated result of the infrared absorption rate of optical parts is 2.8% before heat treatment and 4.1% after heat treatment.

As a protective window for laser processing machines, the infrared absorption rate is preferably 3.0% or less, and the lower the better. Since the infrared absorption rate of the protective window 15 of the first embodiment before and after the heat treatment is less than 3.0%, the protective window 15 of the laser processing machine 1 has sufficient optical performance. In addition, compared with Comparative Example 1 of the conventional optical component, the infrared absorption rate of the protective window 15 of Embodiment 1 after the heat treatment is about half. From the above results, it can be confirmed that the heat resistance of the protective window 15 of Embodiment 1 is improved compared to conventional optical components.

In this way, according to the protective window 15 of the first embodiment, Ge is used as the substrate 150 and the oxide film 21, the fluoride amorphous film 22, the Ge film 23, and the oxide film 21, the fluoride amorphous film 22, the Ge film 23, and the DLC film 24. Thereby, the protective window 15 of Embodiment 1 has high transmittance, heat resistance, and abrasion resistance. Therefore, the protective window 15 of the first embodiment can reduce the laser light loss of the laser processing machine. In addition, the protective window 15 of the first embodiment can exhibit stable optical performance even if it is exposed to high heat during laser processing.

Implementation form 2.

Next, the protective window 15B of Embodiment 2 will be described using FIG. 4. The protection window 15B of the second embodiment has a configuration in which a multilayer film 2B is formed on the main surface 150A of the substrate 150, and this point is different from the protection window 15 of the first embodiment. The other structure is the same as that of the first embodiment.

The multilayer film 2 of the first embodiment is formed of a film including four layers of an oxide film 21, a fluoride amorphous film 22, a Ge film 23, and a DLC film 24 stacked in this order from the side close to the substrate 150. On the other hand, the multilayer film 2B of the second embodiment is formed as shown in FIG. 4, including an oxide film 21, a fluoride amorphous film 22, and a second layer which are sequentially stacked from the side close to the substrate 150. Dioxide film 25, Ge film 23, and DLC film 24 are composed of five layers.

The second oxide film 25 has the effect of making the weakest interface between the fluoride amorphous film 22 and the Ge film 23 adhere to the multilayer film 2B and suppressing the peeling of the multilayer film 2B.

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 anti-reflection 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 formed by sequentially depositing the oxide film 21 (Y ₂ O ₃ : film thickness 25 nm) and the fluoride amorphous film 22 ( YF ₃ : a film thickness of 570 nm), a second oxide film 25 (Y ₂ O ₃ : a film thickness of 25 nm), a Ge film 23 (a film thickness of 120 nm), and a DLC film 24 (a film thickness of 150 nm) are laminated and formed.

On the other hand, the second surface 150B of the substrate 150 is formed with an anti-reflection film 30 having a transmittance of 99% or more at a wavelength of 9.3 μm. _{The anti-reflection film 30 is composed of YF 3} film (film thickness 670nm), Ge film (film thickness 130nm), and MgF ₂ film (film thickness 200nm) layered in order from the side close to the second surface 150B of the substrate 150 . In addition, the structure of the anti-reflection film 30 is not limited to this.

Here, other elements may be added to the layers constituting the multilayer film 2B as long as it does not cause the effect of degrading the optical performance and mechanical properties of the multilayer film 2B. Moreover, as long as it does not cause the influence of deteriorating the optical properties and mechanical properties of the multilayer film 2B, other thin films may be formed in addition to the layers constituting the multilayer film 2B. Furthermore, the oxide film 21 and the second oxide film 25 may be films using the same oxide, or may be films using different types of oxides.

In this way, the multilayer film 2B of the second embodiment is formed by forming 5 of the oxide film 21, the fluoride amorphous film 22, the second oxide film 25, the Ge film 23, and the DLC film 24 in this order from the side close to the substrate 150. Layered film. With this, the protective window 15B of the second embodiment is equipped with It has excellent heat resistance and can stably exhibit optical performance even in high temperature environments.

Furthermore, the protective window 15B of the second embodiment can make the fluoride amorphous film 22 and the Ge film 23 dense by having the second oxide film 25 between the fluoride amorphous film 22 and the Ge film 23. This prevents peeling of the multilayer film 2B.

2‧‧‧Multilayer film

15‧‧‧Protection window (optical parts)

21‧‧‧Oxide film

22‧‧‧Fluoride amorphous film

23‧‧‧Ge film

24‧‧‧DLC film

150‧‧‧Substrate

150A‧‧‧Main side

150B‧‧‧Second side

Claims (6)

An optical component having a substrate, having a main surface and a second surface formed on the back side of the main surface, a multilayer film formed on the main surface, and an anti-reflection film formed on the second surface and being in contact with the multilayer film The difference is that the substrate is formed by containing Ge (germanium), and the multilayer film includes an oxide film, a fluoride amorphous film, and Ge that are directly laminated on the substrate in order from the side close to the substrate. A film made up of at least 4 layers of film and DLC film. An optical component having a substrate, including a main surface, a second surface formed on the back side of the main surface, and a multilayer film formed on at least the main surface among the main surface and the second surface, wherein the substrate is It is formed by containing Ge (germanium), and the multilayer film includes at least four layers of an oxide film, a fluoride amorphous film, a Ge film, and a DLC film, which are sequentially stacked from the side close to the substrate, and are directly stacked on the substrate. In the formed film, the oxide film and the fluoride amorphous film are adjacent to each other. The optical component described in item 1 or 2 of the scope of patent application, wherein the aforementioned oxide film is formed by containing _{any one of Y 2} O ₃ , HfO ₂ and ZrO ₂ , and the aforementioned fluoride amorphous film contains YF _3. It is formed by any one of _{YbF 3} and MgF _2. Optical components as described in item 3 of the scope of patent application, of which The thickness of the oxide film is 5 to 150 nm, the thickness of the fluoride amorphous film is 500 to 950 nm, the thickness of the Ge film is 50 to 150 nm, and the thickness of the DLC film is 50 to 300 nm. The optical component described in claim 4, wherein a second oxide film is provided between the fluoride amorphous film and the Ge film, and the second oxide film contains Y ₂ O ₃ , HfO ₂ and Any one of ZrO ₂ is formed, and the thickness of the aforementioned second oxide film is 5 to 150 nm. A laser processing machine having a laser oscillator and an optical system with laser light irradiated from the aforementioned laser oscillator, the aforementioned optical system having the optical component described in item 4 or 5 of the scope of patent application, and the aforementioned optical component The main surface is arranged to face the processing space side.

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