Patent Application
20250101591
The present invention relates to a method for producing a corrosion-resistant member comprising a substrate consisting of aluminum or an aluminum alloy and an yttria coating formed on a surface of the substrate, and a laser CVD device, specifically, a method for producing a corrosion-resistant member, wherein an yttria coating is formed by irradiating a substrate with laser light in the form of a pulse wave while the substrate is blown with a raw material gas containing yttrium, and a laser CVD device for obtaining the corrosion-resistant member.
In etching devices, which are one of semiconductor production devices, plasma etching with highly corrosive halogen gas such as fluorine and chlorine is performed. Accordingly, being exposed to corrosive gas and plasma, parts inside etching devices such as electrostatic chucks to support wafers and deposition shields to prevent the attachment of byproducts of etching (depositions) require highly corrosion-resistant materials.
Ceramic sintered bodies such as aluminum oxide (Al2O3: alumina) and aluminum nitride are known as plasma-resistant materials for etching devices. However, these sintered bodies may be affected by corrosive gas such as fluorine and chlorine.
On the other hand, yttrium oxide (Y2O3: yttria), which has superior plasma resistance, is more thermally stable than alumina and also has superior fluorine plasma resistance. However, rare earth elements including yttrium are expensive. Therefore, techniques for obtaining a corrosion-resistant member without the use of a sintered body of yttrium oxide, wherein a surface of a part for which corrosion resistance is required is coated with yttria, have been examined (see Patent Literatures 1 and 2, Non Patent Literature 1).
Among them, Patent Literature 1 discloses a plasma-resistant member including an yttrium oxide coating (Y2O3 coating) formed on a surface of a substrate by means of chemical vapor deposition (CVD). Examples in Patent Literature 1 show that an yttrium oxide coating of 100 μm in thickness was formed on an alumina substrate by performing CVD treatment while the alumina substrate was heated under a substrate heating temperature of 700° C.
Patent Literature 2 discloses a corrosion-resistant member including an yttrium oxide coating formed on a surface of a substrate by means of a laser CVD method to form a coating by laser irradiation.
Examples 1 to 5 in Patent Literature 2 show that an yttrium oxide coating of 50 μm in thickness was formed on a surface of an alumina substrate by blowing the alumina substrate, which was placed on a sample stage with a heater, with a mixed gas of an organometal complex containing yttrium and oxygen gas and irradiating the alumina substrate with a YAG laser (a semiconductor laser in Example 5) via a window of a chamber while the aluminum substrate was heated to 600 to 800° C.
Non Patent Literature 1 discloses that an yttrium oxide coating is formed on an alumina substrate board at a deposition speed of 270 μm/h through high-speed synthesis of yttrium oxide by means of the same laser CVD method. Non Patent Literature 1 states that the deposition speed in common CVD is several micrometers per hour (see lines 8 to 9 in the right column on page 845).
Patent Literature 2 presented above discloses Example 6, in which an yttrium oxide coating was formed in the same manner as in Examples 1 to 5 except that an aluminum substrate was used in place of an alumina substrate. According to the examples, for which the laser light used therein is understood to be in the form of a continuous wave, the laser CVD method with the YAG laser as a light source caused the melting of an aluminum substrate and thus had difficulty in forming an yttrium oxide coating, whereas the semiconductor laser was able to form an yttrium oxide coating even on an aluminum substrate, giving a product having strength necessary for structural materials and being preferable as a constituent material of semiconductor production devices.
Non Patent Literature 1: Teiichi Kimura, Ryan Banal, Takashi Goto, “Preparation of Structure-Graded Yttria Film by laser CVD”, Journal of the Japan Society of Powder and Powder Metallurgy, Japan Society of Powder and Powder Metallurgy, Vol. 52, No. 11 (November 2005), pp. 845-850
The multi-patterning technology in production of semiconductor chips has enabled the formation of finer patterns in recent years. The need for more etching steps because of this has resulted in growing demand for etching devices.
As described above, in such a circumstance that parts to be used inside etching devices require highly corrosion-resistant materials, it is effective to coat surfaces of parts with an yttrium oxide coating (yttria coating), which is superior in both plasma resistance and corrosion resistance. In particular, laser CVD to form a coating by laser irradiation gives much higher deposition speed than CVD with common heating means such as high-frequency induction heating, thus being expected to be promising as a high-speed process for plasma-resistant, corrosion-resistant coatings, which require relatively large thickness such as several tens to several hundreds of micrometers.
While alumina substrate boards are mainly used as a substrate to form an yttria coating thereon by means of conventional laser CVD, using aluminum (or an aluminum alloy), which is superior in mechanical processability, heat dissipation properties, and so on, would be advantageous in constituting the aforementioned parts inside etching devices such as electrostatic chucks and deposition shields. However, the melting point of aluminum is 660° C., which is extremely lower than the melting point of alumina, 2072° C. Hence, aluminum is melted by irradiation with laser light in laser CVD. Patent Literature 2 presented above discloses that an yttria coating was formed without any problem by means of a semiconductor laser, whereas an actual trial conducted by the present inventors has found that burning, a phenomenon in which aluminum as a substrate partially melts, occurred to result in a swollen yttria coating or the formation of vacancies in the substrate, causing a problem in mechanical strength required for corrosion-resistant members.
In view of this, the present inventors have diligently examined on a method for forming a corrosion-resistant member by means of laser CVD, the corrosion-resistant member including a substrate of aluminum or an aluminum alloy and an yttria coating on a surface thereof, and found that deposition with a pulse laser, which produces a pulse wave, while a substrate consisting of aluminum or an aluminum alloy is under temperature control to have a specific temperature prevents the substrate from being overheated to inhibit the burning, enabling the formation of an yttria coating, and thus completed the present invention.
Accordingly, an object of the present invention is to provide a method for producing a corrosion-resistant member, wherein the method enables the formation of an anodized aluminum coating with the occurrence of burning due to irradiation with laser light prevented in spite of the inclusion of aluminum or an aluminum alloy as a substrate, and the corrosion-resistant member is suitable for forming parts to be used under an environment involving exposure to corrosive gas and plasma such as the inside of an etching device.
Another object of the present invention is to provide a laser CVD device to be used for obtaining such a corrosion-resistant member.
Specifically, the summary of the present invention is as follows.
(1) A method for producing a corrosion-resistant member comprising a substrate consisting of aluminum or an aluminum alloy and an yttria coating formed on a surface of the substrate, the method comprising:
The present invention enables the formation of an anodized aluminum coating with the occurrence of burning due to irradiation with laser light prevented in spite of the inclusion of aluminum or an aluminum alloy as a substrate. Accordingly, the present invention can give a corrosion-resistant member that is suitable for forming parts to be used under an environment involving exposure to corrosive gas and plasma such as the inside of an etching device and at the same time superior in mechanical processability.
The following describes the method of the present invention for producing a corrosion-resistant member and the laser CVD device for use in the method in detail. Some or all of components of the present invention that are described in the following can be appropriately combined.
First, the substrate that is used for the production of a corrosion-resistant member in the present invention consists of aluminum or an aluminum alloy. These are distinguished by their purity, and typically aluminum having a purity of 99.0% or more is regarded as pure aluminum, and aluminum with an additional alloy element as an aluminum alloy. Aluminum alloys are classified by main additional elements into several alloy systems such as 3000 series and 5000 series. Aluminum or an aluminum alloy of appropriate type can be selected for use in view of the application of the corrosion-resistant member and strength required therefor, processability, and the corrosion resistance of the substrate itself.
The substrate may be a processed material obtained by appropriately processing into a desired shape or a composite material or the like obtained by appropriately combining such processed materials. The thickness of the substrate depends on the application of the corrosion-resistant member and cannot be definitely specified, whereas a thickness of about 0.1 mm to 500 mm is typically employed. An oxide film is typically formed on the surface of aluminum or an aluminum alloy. This oxide film may be a natural oxide film naturally formed in the atmosphere, or an anodic oxide film formed through anodic oxidation, or a rolled oxide film formed through hot rolling.
A substrate having an oxide film on the surface or a substrate having no oxide film on the surface may be used as the substrate for use in the production of the corrosion-resistant member. If the substrate has an anodic oxide film formed through anodic oxidation on the surface, the substrate and the corrosion-resistant member each have improved plasma resistance and corrosion resistance. Accordingly, for enhanced plasma resistance and corrosion resistance in the substrate and the corrosion-resistant member, it is preferred to use a substrate having an anodic oxide film on the surface to form an yttria coating on the anodic oxide film. If the substrate has an anodic oxide film on the surface, on the occurrence of burning in forming an yttria coating on the outer surface of the anodic oxide film, the anodic oxide film may peel off because of a vacancy generated between the inner surface of the anodic oxide film and the substrate. Accordingly, for avoiding the peeling-off of the anodic oxide film after the formation of an yttria coating to achieve enhanced adhesion, forming an yttria coating with inhibiting burning is required.
The yttria coating to be formed on a surface of the substrate consists of yttrium oxide (Y2O3, yttria), and is formed by means of laser CVD to irradiate the substrate with laser light while the substrate is blown with a raw material gas containing yttrium. The presence of the yttria coating formed on a surface of the substrate can be confirmed, for example, by observing a surface or cross-section of the corrosion-resistant member by means of scanning electron microscopy (SEM). In identification of the yttria coating, for example, the yttria coating can be confirmed from the presence of a peak of the characteristic X-ray of yttrium (Y) and a peak of the characteristic X-ray of O in energy-dispersive X-ray spectroscopy (EDX, EDS).
The thickness of the yttria coating is not particularly limited, but the yttria coating is desired to be thicker for ensuring plasma resistance and corrosion resistance. On the other hand, an upper limit can be set in view of saturation of the effects and economic efficiency. Accordingly, the thickness is preferably 0.1 μm or more, more preferably 1 μm or more, and preferably 100 μm or less, more preferably 10 μm or less.
The corrosion-resistant member obtained in the present invention includes an yttria coating, which is superior in plasma resistance and corrosion resistance, and a substrate consisting of aluminum or an aluminum alloy, which is superior in mechanical processability, heat dissipation properties, and so on, and hence is preferably used for production of parts of semiconductor production devices, in which wafers are processed under exposure to corrosive gas or plasma. Especially, the corrosion-resistant member is particularly preferable for constituent parts of etchers in semiconductor production devices such as plasma etching devices, in which plasma etching is performed, and specific examples include not only electrostatic chucks and deposition shields mentioned above, but also cooling plates, which are used in contact with an electrode, upper walls constituting a part of a chamber, and side jackets. In addition to these, the corrosion-resistant member can be used for various materials including parts and housings of devices for which plasma resistance or corrosion resistance is required.
The method of the present invention for producing a corrosion-resistant member may include, prior to a coating formation step, a reflectance reduction step of reducing the reflectance of an irradiation target surface of a substrate to be irradiated with laser light. In this way, the reflectance reduction step and the coating formation step may be performed in the presented order to allow an yttria coating to more reliably grow while the melting of the substrate is inhibited to prevent the occurrence of burning. Specifically, the substrate can more reliably accumulate thermal energy by virtue of the reduced reflectance of the substrate to the laser light to be used in the coating deposition step. In this case, suitably, the reflectance of an irradiation target surface of the substrate to be irradiated with laser light to be used in the coating formation step at the wavelength of the laser light is preferably set to 50% or less, more preferably to 40% or less.
Any technique is available to reduce the reflectance of the irradiation target surface of the substrate without particular limitation, and examples thereof include a method of applying a light-absorbing material that absorbs the laser light onto the irradiation target surface of the substrate, a method of roughening the irradiation target surface of the substrate, and a method of blackening the irradiation target surface of the substrate. In the method of applying a light-absorbing material among them, a near-infrared-light-absorbing material corresponding to the laser to be used can be applied. In the method of roughening the irradiation target surface, for example, roughening treatment can be performed by means of blasting treatment, anodic oxidation treatment, boehmite treatment, or the like. In the method of blackening the irradiation target surface, the irradiation target surface of the substrate can be blackened by subjecting to treatment with application of or soaking in a black dye or a dark coating material, or by subjecting to electrolytic deposition treatment, or the like in which an anodic oxide film formed through anodic oxidation treatment is subjected to secondary electrolysis to electrolytically deposit Ni, Co, or the like.
In the method of the present invention for producing a corrosion-resistant member, an yttria coating is formed on a substrate consisting of aluminum or an aluminum alloy by means of what is called laser CVD.
Specifically, an yttria coating is formed on a surface of a substrate consisting of aluminum or an aluminum alloy by irradiating the substrate with laser light in the form of a pulse wave while the substrate is blown with a raw material gas containing yttrium.
In the present invention, the melting of the substrate, which consists of aluminum or an aluminum alloy, can be inhibited to prevent the occurrence of burning with the use of laser light in the form of a pulse wave. Any laser that produces a pulse wave can be used without particular limitation, and, for example, a YAG laser, a YVO4 laser, a semiconductor laser, a fiber laser, an excimer laser, an argon laser, or the like can be used.
Here, for irradiating the substrate with laser light, for example, the following laser conditions can be exemplified. First, the average output is typically 5 to 2000 W, and preferably 10 W or more, more preferably 15 W or more, even more preferably 20 W or more, and preferably 1000 W or less, more preferably 100 W or less, even more preferably 50 W or less. The frequency is typically 1 to 100 kHz, and preferably 10 kHz or more, more preferably 20 kHz or more, and preferably 50 kHz or less, more preferably 40 kHz or less. The pulse width is typically 1 to 1000 ns, and preferably 10 ns or more, more preferably 50 ns or more, even more preferably 100 ns or more, and preferably 500 ns or less, more preferably 300 ns or less, even more preferably 200 ns or less. The peak power is typically 100 W to 30 kW, and preferably 1 kW or more, more preferably 5 kW or more, even more preferably 10 kW or more, and preferably 25 kW or less, more preferably 20 kW or less, even more preferably 15 kW or less. The pulse energy is typically 0.1 to 30 mJ, and preferably 0.5 mJ or more, more preferably 1 mJ or more, even more preferably 2 mJ or more, and preferably 10 mJ or less, more preferably 5 mJ or less, even more preferably 3 mJ or less. The average energy density in laser irradiation (laser irradiation density) is typically 10 to 1000 W/mm2, and preferably 20 W/mm2 or more, more preferably 40 W/mm2 or more, even more preferably 80 W/mm2 or more, and preferably 500 W/mm2 or less, more preferably 200 W/mm2 or less, even more preferably 100 W/mm2 or less. For those conditions, the average output indicates the oscillation output of the laser. The pulse width is a time width per pulse oscillated from the pulse laser. The pulse energy indicates the energy of one pulse contained in the pulse laser beam. The peak power corresponds to a value calculated by dividing the pulse energy by the pulse width (pulse energy≈peak power×pulse width). The average energy density at laser irradiation indicates the average output of the laser emitted per unit area of the irradiation target surface of the substrate to be irradiated with the laser (laser irradiation density=average output/irradiated area).
In the present invention, the temperature of the substrate in the deposition for forming the yttria coating in the coating formation step is typically 300 to 600° C., and preferably 350° C. or more, more preferably 400° C. or more, and preferably 550° C. or less, more preferably 500° C. or less. If the temperature of the substrate in the deposition is less than 300° C., the yttria coating may be insufficiently formed; if the temperature of the substrate in the deposition is more than 600° C., on the other hand, burning may occur because of the melting of the substrate. For the temperature of the substrate in the deposition, it is difficult to directly measure just the temperature of the substrate in a chamber of a CVD device during the deposition. Hence, in the present invention, the surface temperature of the substrate during the deposition is measured from the outside of a chamber with a radiation thermometer, and the value is regarded as the temperature of the substrate in the deposition.
Here, in order to set the temperature of the substrate in the deposition to the aforementioned temperature, it is appropriate to form the yttria coating on the substrate placed on a sample stage in a chamber of a CVD device with the sample stage being under temperature control to have a temperature of 0° C. to 200° C. Specifically, it is preferable to cool the sample stage with a liquid refrigerant, and the resulting temperature is typically 0° C. to 200° C., and preferably 10° C. or more, more preferably 20° C. or more, even more preferably 30° C. or more, and preferably 100° C. or less, more preferably 50° C. or less, even more preferably 40° C. or less.
In forming the yttria coating, the substrate is irradiated with laser light in the form of a pulse wave while the substrate is blown with a raw material gas containing yttrium in such a manner that the substrate is blown with the raw material gas. At that time, an organometal complex containing yttrium can be used as with the case of forming an yttria coating through CVD by a known method. Specifically, for example, an acetylacetonate metal complex such as tris(acetylacetonato)yttrium or a dipivaloylmethane metal complex such as tris(dipivaloylmethanato)yttrium can be preferably used. These react with oxygen such as oxygen gas separately fed to form yttrium oxide (yttria). At that time, the deposition rate for the yttria coating is not particularly limited, and is typically 10 to 1000 μm/Hr because laser CVD is used, and preferably 100 μm/Hr or more, more preferably 200 μm/Hr or more, and preferably 500 μm/Hr or less, more preferably 400 μm/Hr or less.
Examples of preferred laser CVD devices applicable as a laser CVD device for use in the method of the present invention for producing a corrosion-resistant member include, but are not particularly limited to, the following one: a laser CVD device including: a vacuum chamber; a sample stage on which a substrate is placed in the vacuum chamber; a gas-feeding unit that feeds a raw material gas to the substrate; a laser unit that irradiates the substrate with laser light via an optical window attached to the vacuum chamber; and a cooling unit that cools the sample stage via a refrigerant.
To produce a corrosion-resistant member by forming an yttria coating on a surface of a substrate consisting of aluminum or an aluminum alloy with this laser CVD device, first, the substrate 3 is placed on the sample stage 2 at a predetermined position. The temperature of the substrate 3 placed on the sample stage 2 is set to a specific temperature with the cooling unit 9, and then an organometal complex (MO) preheated to a specific temperature is jetted together with Ar gas as a carrier gas from the raw-material-feeding pipe 5. At that time, a liquid refrigerant (water) cooled with an external chiller or the like can be circulated in the cooling unit 9. At the same time, oxygen (O2) is jetted from the oxygen-feeding pipe 6. Through this process, a surface of the substrate 3 is blown with a mixed gas (raw material gas) as a mixture of those materials.
Subsequently, simultaneously with blowing the surface of the substrate 3 with the mixed gas, the substrate 3 is irradiated with laser light in the form of a pulse wave from a laser unit 4 such as a fiber laser via the optical window 8 of the vacuum chamber 1. At that time, when the mixed gas with which the surface of the substrate 3 has been blown is irradiated with the laser light, the organometal complex containing yttrium is activated through local heating, and reacts with oxygen to crystalize on the surface of the substrate 3. These crystals grow to form an yttria coating having a specific thickness on the surface of the substrate 3. At that time, the substrate 3 placed on the sample stage 2 is cooled by the cooling unit 9, and the cooling in combination with the pulse oscillation from the laser unit 4 allows the substrate 3 to be under control to have a specific temperature (300° C. to 600° C.). At that time, the temperature of the substrate 3 in the deposition is measured with the radiation thermometer 12, and the measurement result may be used for adjustment of, for example, the output of the laser unit 4 or the refrigerant temperature of the cooling unit 9. An excessive portion of the gas in the vacuum chamber 1 during the deposition is exhausted from the exhaust port 10 to the outside.
In the method of the present invention for producing a corrosion-resistant member, a surface of the substrate, which consists of aluminum or an aluminum alloy, is irradiated with laser light consisting of a pulse wave, and as a result high energy is instantaneously given to the raw material gas and the growth of yttria crystals is promoted. At that time, as a result of the use of a pulse wave, the substrate is intermittently irradiated with the laser light and subjected to repeated heating and cooling. Thus, even if the laser output is comparable to that in the case of a continuous wave, the substrate can receive heat from the laser light while allowing an yttria coating to grow on the surface of the substrate with the heat inhibited from propagating to the inside of the substrate, and hence the occurrence of burning, a phenomenon that the substrate melts and a vacancy is formed in the inside of the substrate, can be prevented. In this way, the present invention enables production of a corrosion-resistant member having improved plasma resistance and corrosion resistance even with a substrate consisting of a material having a relatively low melting point such as aluminum or an aluminum alloy through the formation of an yttria coating with the melting inhibited. In addition, the present invention enables production of a corrosion-resistant member with a substrate consisting of aluminum or an aluminum alloy, the substrate having satisfactory mechanical processability and heat dissipation properties, and thus production of a corrosion-resistant member having a desired shape or being superior in heat dissipation properties.
The following describes preferred embodiments of the present invention in detail with Examples, Comparative Examples, and test examples, but the description should not be construed as limitation of the present invention thereto.
A test substrate of 1 mm in thickness×30 mm in width×30 mm in length was cut out of A5052 aluminum alloy treated according to the temper designation H34 (A5052-H34) shown in JIS H0001, and a test corrosion-resistant member according to the present invention was produced by means of laser CVD as follows.
First, as a reflectance reduction step, an irradiation target surface of the test substrate to be irradiated with laser light was blackened by coloring with a marker to reduce the reflectance. The resulting reflectance at 1060 nm, which is the wavelength of a Yb fiber laser to be used for a laser CVD device described later, was 37.6% as shown in
Subsequently, the blackened test substrate was placed on a sample stage of a laser CVD device. The laser CVD device used in Examples was of vertical cold-wall type as previously shown in
The test substrate 3 placed on the sample stage 2 was cooled in advance with the cooling unit 9, and an organometal complex (MO): Y(C11H19O2)3 [tris(dipivaloylmethanato)yttrium] that had been heated to a specific temperature to be vaporized was jetted together with Ar gas as a carrier gas from the raw-material-feeding pipe 5 toward a surface of the substrate 3. At the same time, oxygen (O2) was jetted from the oxygen-feeding pipe 6. This configuration allowed the surface of the substrate 3 to be blown with a mixed gas (raw material gas) as a mixture of those raw materials.
Subsequently, simultaneously with blowing the surface of the test substrate 3 with the mixed gas, the test substrate 3 was irradiated with laser light in the form of a pulse wave from the laser unit 4, which included a Yb fiber laser as a laser oscillator, via an optical window 8. At that time, the cooling of the sample stage 2 with the cooling unit 9 in combination with the pulse oscillation from the laser unit 4 allowed the test substrate 3 to keep a specific temperature with the temperature increase of the test substrate 3 inhibited in the formation of an yttria coating, and the temperature of the test substrate 3 at that time was measured with the radiation thermometer 11. Then, while the pressure in the vacuum chamber 1 was reduced to a specific pressure by exhausting an excessive portion of the gas in the vacuum chamber 1 in the deposition from the exhaust port 10 to the outside, a coating formation step was performed to form an yttria coating on the surface of the test substrate 3. Details of the laser conditions and deposition conditions in the coating formation step and the deposition result were as shown below. The peak power and pulse energy of the laser conditions are based on a data sheet for the laser unit. The deposition result is based on observation by cross-sectional SEM. For the measurement of the temperature of the test substrate in the deposition, a radiation thermometer (FLHX-TNN0220L0500S3.2-000 manufactured by JAPANSENSOR CORPORATION) was used. In the measurement, the emissivity of the aluminum alloy (A5052-H34) was employed irrespective of the condition of the surface of the test substrate and an emissivity of 0.2 was set, and the temperature of a part of the test substrate with the occurrence of deposition was measured. The measurement range of the radiation thermometer in the measurement was φ3.2 mm.
For the test corrosion-resistant member obtained through the reflectance reduction step and the coating formation step,
A5052-H34 of 4 mm in thickness×30 mm in width×30 mm in length was used as a test substrate. This was blackened by coloring with a marker in the same manner as in Example 1 to give a reflectance of 37.6% at 1060 nm, which is the wavelength of a Yb fiber laser. The test substrate was placed on the sample stage of the laser CVD device in the same manner as in Example 1, and an yttria coating was formed on a surface of the test substrate 3 in the same manner as in Example 1 except that laser conditions and deposition conditions shown below were applied. The deposition result is shown in combination with the laser conditions and others.
For the test corrosion-resistant member obtained above,
A5052-H34 of 1 mm in thickness×5 mm in width×5 mm in length was used as a test substrate. The test substrate was degreased in advance with ethanol without being subjected to a reflectance reduction step, and placed on the sample stage of the laser CVD device in the same manner as in Example 1. In Comparative Example 1, a semiconductor laser that produces a continuous wave was used as a laser oscillator of the laser CVD device, and the reflectance of the test substrate degreased with ethanol at 976 nm, which is the wavelength of the semiconductor laser, was 85.78. Then, a coating formation step according to Comparative Example 1 was performed in the same manner as in Example 1 except that laser conditions and deposition conditions shown below were applied. The deposition result is shown in combination with the laser conditions and others.
For the test corrosion-resistant member obtained above,
A5052-H34 of 1 mm in thickness×5 mm in width×5 mm in length was used as a test substrate. As a reflectance reduction step, the test substrate was subjected to roughening treatment by anodic oxidation with sulfuric acid to provide a sulfuric acid anodic oxide film having a thickness of 34 μm. The resulting reflectance at 1060 nm, which is the wavelength of a Yb fiber laser to be used in the laser CVD device in Comparative Example 2, was 51.6%.
Subsequently, the roughened test substrate was placed on the sample stage of the laser CVD device in the same manner as in Example 1. In Comparative Example 2, a Yb fiber laser that produces a continuous wave was used as a laser oscillator of the laser CVD device. Then, a coating formation step was performed in the same manner as in Example 1 except that laser conditions and deposition conditions shown below were applied. The deposition result is shown in combination with the laser conditions and others.
For the test corrosion-resistant member obtained above,
A5052-H34 of 1 mm in thickness×30 mm in width×30 mm in length was used as a test substrate. The test substrate was degreased in advance with ethanol without being subjected to a reflectance reduction step, and placed on the sample stage of the laser CVD device in the same manner as in Example 1. In Comparative Example 3, a Yb fiber laser that produces a pulse wave was used as a laser oscillator of the laser CVD device, and the reflectance of the test substrate degreased with ethanol at 1060 nm, which is the wavelength of the Yb fiber laser, was 88.4%. Then, a coating formation step was performed in the same manner as in Example 1 except that laser conditions and deposition conditions shown below were applied. The deposition result is shown in combination with the laser conditions and others.
The result showed that no yttria coating was formed on the surface of the test substrate. The result in Comparative Example 3 is probably because sufficient increase in the temperature of the test substrate was not achieved during the deposition because of the use of the laser that produces a pulse wave as well as the excessively high reflectance of the test substrate to the laser light.
A test substrate of 1 mm in thickness×5 mm in width×5 mm in length was cut out of A1050 aluminum alloy treated according to the temper designation H24 (A1050-H34) shown in JIS H0001, and this test substrate was used. The test substrate was degreased in advance with ethanol without being subjected to a reflectance reduction step, and placed on the sample stage of the laser CVD device in the same manner as in Example 1. In Comparative Example 4, a semiconductor laser that produces a continuous wave was used as a laser oscillator of the laser CVD device, and the reflectance of the test substrate degreased with ethanol at 976 nm, which is the wavelength of the semiconductor laser, was 85.7%. No cooling unit to cool the sample stage was provided with the laser CVD device in Comparative Example 4. Then, a coating formation step was performed in the same manner as in Example 1 except that laser conditions and deposition conditions shown below were applied. The deposition result is shown in combination with the laser conditions and others.
For the test corrosion-resistant member obtained above,
As described above, the present invention enables the formation of an yttria coating with a substrate consisting of aluminum or an aluminum alloy, wherein the substrate is prevented from melting and thus inhibited from burning through deposition with the substrate being under temperature control to have a specific temperature by using a pulse laser that produces a pulse wave. Accordingly, the present invention enables production of a corrosion-resistant member superior in plasma resistance and corrosion resistance with a substrate consisting of aluminum or an aluminum alloy, and the resulting corrosion-resistant member is very preferable as a material for parts and housings to be used under an environment involving exposure to corrosive gas and plasma such as the inside of a semiconductor production device.
1: vacuum chamber, 2: sample stage, 3: substrate, 4: gas-feeding unit, 5: raw-material-feeding pipe, 6: oxygen-feeding pipe, 7: laser unit, 8: optical window, 9: cooling unit, 10: exhaust port, 11: measurement window, 12: radiation thermometer, 13: yttria coating, 14: test substrate, 15: anodic oxide film, 16: vacancy.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-022675 | Feb 2022 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2023/004651 | 2/10/2023 | WO |
