JP3341007B2 - Aluminum hollow waveguide and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a light source capable of transmitting light in a wide wavelength range from the ultraviolet to the infrared.
The present invention relates to a hollow waveguide and a method for manufacturing the same.

[0002]

2. Description of the Related Art An excimer laser which oscillates in the ultraviolet wavelength range is characterized in that a pulse having a short oscillation width is generated with a high oscillation efficiency, so that an extremely large peak output can be obtained. Therefore, application to industrial fields such as cutting / perforating a metal plate, surface treatment, and removal of a coating film using a vaporization or ablation of a substance induced by a large energy of ultraviolet light is progressing. In the medical field as well, practical application is being promoted in a wide range of fields such as removal of tumors, spots and bruises.

[0003] By the way, in a quartz optical fiber for general communication, the transmission loss of ultraviolet light having a wavelength of about 200 nm sharply increases due to the inherent glass phenomenon such as Rayleigh scattering and two-photon absorption. Would. Therefore, an ordinary silica-based optical fiber cannot be used as a transmission path for excimer laser light that generates large energy. For this reason, specially treated pure silica glass fibers and the like have been developed. However, even with these fibers, loss is particularly high for excimer lasers using KrF or ArF gas as a laser medium and having a short oscillation wavelength. And many problems in terms of durability and are not suitable for transmitting large energy.

[0004] Therefore, a hollow waveguide using air as a core, in which Rayleigh scattering is so small as to be negligible, is being studied as a transmission line of an excimer laser. In order to efficiently transmit light in the ultraviolet region, a metal exhibiting high reflectivity, such as aluminum, is suitable for the material of the waveguide, and its surface must be extremely smooth to suppress scattering loss. is there. Therefore, as shown in FIG. 4, the conventional hollow waveguide is formed by using two strips of an optically polished aluminum plate or a metal plate 11A on which an aluminum thin film is formed by a vacuum evaporation method using a spacer 11B. It was a combination of rectangles.

On the other hand, an infrared laser having a wavelength of 2 μm or more also has an infrared absorption caused by molecular resonance of glass.
Since ordinary silica-based fibers cannot be used because of high loss, hollow waveguides are useful in many fields of medicine and industry. Conventionally, a silver thin film has been formed on the inner surface of a hollow waveguide using a silver mirror reaction by a liquid phase method.

[0006]

However, in the hollow waveguide for transmitting ultraviolet laser according to the prior art shown in FIG. 4, the direction in which it can be bent is limited due to its structure, and the cross-sectional dimension of the waveguide is also limited. It is relatively large, about 8 mm in width and about 2 mm in thickness, and has a great difficulty in terms of flexibility. Therefore, in fields such as clinical applications where high flexibility is required for waveguides, there is a problem in operability, and practical use has been difficult. In addition, the manufacturing process is also complicated and costly, such as starting from optical polishing of a metal plate, aluminum deposition, assembling and reinforcing, and mass production is difficult.

On the other hand, in a hollow waveguide for an infrared laser, since a relatively large surface roughness is present in a silver thin film formed by a silver mirror reaction, scattering occurs when laser light is reflected on the inner surface of the waveguide. Loss occurs. Further, in the silver mirror reaction, it is difficult to remove impurities from the formed silver thin film, so that absorption loss occurs in the infrared region, and further,
The chemical reaction induced by the impurities causes a problem in the chemical and thermal durability of the waveguide. In addition, since the raw material is a liquid, it is impossible to flow the raw material uniformly in an extremely thin pipe, and it is difficult to manufacture a small-diameter hollow waveguide having high flexibility.

Accordingly, an object of the present invention is to provide a hollow waveguide which solves the above-mentioned problems, has excellent flexibility, can be mass-produced, transmits light in the ultraviolet to infrared region with low loss, and a method of manufacturing the same. It is in.

[0009]

According to the present invention, there is provided a hollow waveguide in which a thin film of aluminum is formed on an inner wall of a pipe made of glass, metal or plastic. I will provide a.

Here, the hollow waveguide may be one in which a dielectric thin film of an inorganic or organic resin is provided on the inner wall surface of the aluminum thin film, and the dielectric oxidizes the surface of the aluminum. The formed aluminum oxide may be used.

[0011] The method for manufacturing a hollow waveguide according to the present invention comprises:
A method of manufacturing a hollow waveguide, comprising forming a thin film of aluminum on an inner wall surface of a pipe by a chemical vapor deposition method while flowing a vapor of an aluminum organic compound into a hollow region of a metal or nonmetal pipe.

Here, as a pretreatment for forming the aluminum thin film, it is preferable to flow titanium chloride vapor into the hollow region of the pipe. Further, the aluminum organic compound is trimethylamine alane, triethylamine alane,
Any of dimethylethylaminealane, trimethylaluminum, triethylaluminum, or triisobutylaluminum is preferred. Also, by bundling multiple pipes when producing aluminum,
It is preferable to form a thin film of aluminum simultaneously on the inner surfaces thereof.

[0013] The hollow waveguide of the present invention exhibits low loss with respect to light of a wide range of wavelengths from ultraviolet to infrared, and is excellent in flexibility and durability. And practical in a wide range of industries.

Further, according to the hollow waveguide manufacturing method of the present invention, it is possible to form an aluminum thin film having an extremely smooth surface on the inner surface of a hollow pipe made of various materials, and to prevent light in the ultraviolet region. In addition, it is possible to manufacture a waveguide with small additional loss due to scattering. In the manufacturing method of the present invention, since the raw material is allowed to flow into the pipe as vapor, the raw material can be uniformly flowed even in an extremely thin pipe, and a small-diameter hollow waveguide excellent in flexibility is manufactured. be able to. Furthermore, according to this manufacturing method, since a plurality of pipes can be bundled to simultaneously form an aluminum thin film, mass productivity is excellent.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing one embodiment of the hollow waveguide of the present invention. As shown in the figure,
An aluminum hollow waveguide 1 is formed by a pipe 1A, an aluminum thin film 1B provided on the inner wall of the pipe 1A, and a hollow region 1C defined by the inner wall of the aluminum thin film 1B.

Light incident on the hollow waveguide 1 repeatedly propagates at the boundary between the hollow region 1C and the aluminum thin film 1B. The aluminum thin film 1B needs to be thicker than the skin depth so that light energy does not seep into the pipe 1A at the time of reflection. However, if it is too thick, an increase in surface roughness or a decrease in adhesion strength to the pipe 1A is required. In this embodiment, the film thickness is set to 50 nm in accordance with the wavelength of light used.
From 500 nm.

In order to suppress the transmission loss of the hollow waveguide 1, the light reflectance on the inner surface of the waveguide is large, and
% Is desirable. In that regard, aluminum exhibits a high reflectance over a wide wavelength range from ultraviolet to infrared, and is therefore suitable as a material for the hollow waveguide. Also,
In particular, for light having a short wavelength in the ultraviolet region, if there is surface roughness at the interface between the aluminum thin film 1B and the hollow region 1C,
It is important that the boundary surface be extremely smooth, because the scattering lowers the reflectance and increases the loss.

Since the pipe 1A does not act on light to be transmitted optically, it may be made of any material. However, since the pipe 1A retains the structure of the hollow waveguide 1, it has excellent flexibility and It is necessary to have mechanical strength that can withstand practical use, and its inner diameter is preferably 0.1 mm to 3 mm depending on the wavelength of light used and the application. In addition, since the surface condition of the inner wall of the pipe 1A greatly affects the surface roughness of the boundary surface between the aluminum thin film 1B and the hollow region 1C, it is important that the inner wall of the pipe 1 is sufficiently smooth. Is preferably 0.1 μm or less. Therefore, in the present invention, the material of the pipe 1A is quartz, glass such as Pyrex, plastic such as polycarbonate and Teflon, and metal such as stainless steel and nickel. When glass is used as the pipe 1A, a protective coating such as an acrylic resin or polyimide is applied to the surface of the pipe 1 in order to prevent the glass surface from being finely scratched and reduced in strength. Is preferred.

FIG. 2 is a sectional view showing an example of the embodiment of the present invention, in which a dielectric thin film 2D made of an inorganic or organic resin is formed on the surface of an aluminum thin film 2B. In particular, with respect to light having a wavelength in the infrared region, forming the dielectric thin film 2D on the surface of the aluminum thin film 2B increases the light reflectance, which is effective in reducing the loss of the hollow waveguide.

It is important for the material of the dielectric thin film 2D that the absorption is sufficiently small in the wavelength range of the light to be used, for example, fluorides such as calcium fluoride and magnesium fluoride, quartz, magnesium oxide and zirconium oxide. , Copper oxide, titanium oxide, aluminum oxide,
Metal oxides such as yttrium oxide, semiconductors such as germanium and silicon, and I such as zinc selenide and zinc sulfide
A group I-VI compound or a polymer resin such as polyimide, polycarbonate, polyethylene, polysiloxane, polysiloxane, cyclic olefin resin, fluororesin, and silicone resin can be used. These dielectric thin films 2D
Can be formed on the surface of the aluminum thin film 3 by a liquid phase method or a sol-gel method. The thickness of the thin film 2D is preferably 0.1 μm to 3 μm, depending on the wavelength used.

The dielectric thin film 2D may be aluminum oxide obtained by oxidizing a part of the surface of the aluminum thin film 3 by a treatment such as thermal oxidation.

Next, a method for manufacturing a hollow waveguide according to the present invention will be described.
This will be described with reference to FIG. A raw material vapor gas such as trimethylaminealane, triethylaminealane, dimethylethylaminealane, trimethylaluminum, triethylaluminum, or triisobutylaluminum flows into the pipe 3. In that case,
Depending on the raw material to be used, it may be mixed with an inert gas such as argon or helium or a gas such as oxygen, nitrogen or hydrogen and flow into the pipe 3. In this embodiment, the inner diameter is set to 0.
A quartz and Pyrex glass pipe having a length of 5 to 1.0 mm and a length of 10 to 20 cm is used as the pipe 3.

Of these raw materials, dimethylethylaminealane is easy to handle because of its low spontaneous combustion. In addition, since the vapor pressure is relatively high and the liquid is liquid at room temperature, the vapor is easily generated by bubbling. When dimethylethylaminealane is used as a raw material, a vapor is generated by bubbling the raw material liquid kept at 10 to 20 ° C. with argon, and the vapor is generated inside the pipe 3 at a flow rate of 0.1 to 10 cc per minute. Let it flow in.

A pump 4 such as a turbo molecular pump or an oil diffusion pump for obtaining a high vacuum and a pump 5 for obtaining a large displacement such as a mechanical booster pump are disposed downstream of the pipe 1A. Before the raw material vapor is introduced, the high vacuum pump 4 is driven to remove the air and the like inside the pipe 3, and the pressure in the pipe is reduced to a vacuum of 10 ⁻³ Pa or less. Thereafter, when the raw material vapor is introduced, the pump is switched to the large displacement pump 5 and the pressure is reduced to 1
The flow rate of the raw material and the conductance of the valve are adjusted so as to be 0 to 1000 Pa.

Further, as a pretreatment for aluminum film formation,
When titanium tetrachloride vapor is passed through the pipe, the inner surface of the pipe is activated, and a thin aluminum film can be formed at a low temperature, and an aluminum thin film having an extremely smooth surface can be formed. In this embodiment, the valve of the container 6 containing titanium tetrachloride is opened under a pressure of 10 to 1000 Pa, and the generated steam is allowed to flow into the pipe for about 1 to 3 minutes.

Thereafter, after maintaining the vacuum state for about 30 to 60 minutes, the raw material vapor is caused to flow into the pipe 3. In this state, the pipe 3 is connected to the pipe 8 by using a heating mechanism 7 such as a ring electric furnace.
By heating to 0 to 200 ° C., an aluminum thin film is formed on the inner surface of the pipe 3. If the temperature at this time is too high, the film forming rate becomes too high, and the surface roughness of the aluminum thin film becomes large. Therefore, it is important to set the temperature to the minimum required, and in this embodiment, the temperature is set to 80 to 120 ° C. By heating for about 5 to 60 minutes in this state, an aluminum thin film having a thickness of 50 to 500 nm is formed on the inner surface of the pipe.

FIG. 3B is an explanatory view of an embodiment in which a plurality of long pipes having a length of 1 m are bundled and an aluminum thin film is simultaneously formed on the inner surfaces thereof. In this embodiment, seven glass pipes 8 are bundled and both ends are fixed to the sleeve 9 using an adhesive. The manufacturing process is almost the same as that described above, but in this embodiment, since the pipe 8 is long, the small annular electric furnace 1 heated to 80 to 200 ° C.
0 is repeatedly moved along the pipe 8 in the direction of the arrow. Since the aluminum thin film is formed only on the inner surface of the heated portion of the pipe 8, if the electric furnace 10 is moved at a low speed of 1 to 10 cm per minute, the inner surface of all the bundled long pipes 8 A thin film is formed, and its thickness becomes uniform in the longitudinal direction of the pipe 8. Further, in this embodiment, in order to prevent the raw material vapor from being condensed in the non-heated portion, a large annular furnace and a tape-type heater (not shown) are set so that the entire raw material pipe and pipe 8 are kept at about 25 to 40 ° C. ).

[0028]

In summary, according to the present invention, the following excellent effects are exhibited.

It has excellent flexibility and can transmit light in a wide wavelength range from ultraviolet to infrared with low loss.

It has high chemical stability and excellent durability and heat resistance.

It is easy to reduce the diameter and length of the waveguide,
Excellent mass productivity.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view of a hollow waveguide in which a dielectric thin film is formed on the surface of an aluminum film.

3A and 3B are explanatory diagrams illustrating a method for manufacturing a hollow waveguide according to the present invention, wherein FIG. 3A is an explanatory diagram illustrating a method for manufacturing a short waveguide,
(B) is an explanatory view of a method for simultaneously manufacturing a plurality of long waveguides.

FIG. 4 is a sectional view showing a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 aluminum hollow waveguide 1A pipe 1B aluminum thin film 1C hollow region 2 dielectric-holed aluminum hollow waveguide 2A pipe 2B aluminum thin film 2C hollow region 2D dielectric thin film 3 pipe 4 high vacuum pump 5 large displacement pump 6 titanium tetrachloride container 7 Heating mechanism 8 Long pipe 9 Sleeve 10 Annular furnace 11 Rectangular aluminum hollow waveguide 11A Metal plate 11B Spacer 11C Coating 11D Hollow area

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-278208 (JP, A) JP-A-6-230254 (JP, A) JP-A-1-188804 (JP, A) JP-A-5-208804 188225 (JP, A) JP-A-60-22103 (JP, A) JP-A-62-167887 (JP, A) JP-A-62-74083 (JP, A) JP-A-61-243179 (JP, A) JP-A-63-13003 (JP, A) JP-A-61-264175 (JP, A) JP-A-6-84830 (JP, A) JP-A-2-162302 (JP, A) JP-B-60-48724 (JP, B1) OPTICS LETTERS, Vol. 20, No. 20 (1995) pp. 2078 −2080 (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 6/00 G02B 6/10 G02B 6/16-6/22 G02B 6/44 C23C 16/00-16/56 H01L 21 / 88-21/90 IEEE / IEEE Electronic Library (IEL)

Claims (2)

(57) [Claims] 1. A method in which a heater of a temperature of 80 to 200 ° C. installed near the pipe is moved along the pipe while flowing a vapor of the aluminum organic compound into a hollow area of the glass pipe, thereby forming the pipe in the longitudinal direction of the pipe. A method of manufacturing a hollow waveguide, comprising forming an aluminum thin film having a very uniform surface and an extremely smooth surface by a chemical vapor deposition method. 2. A method in which a heater of a temperature of 80 to 200 ° C. installed near the pipe is moved along the pipe while flowing the vapor of the aluminum organic compound into the hollow area of the glass pipe, thereby forming the pipe in the longitudinal direction of the pipe. A hollow waveguide manufactured by forming an aluminum thin film having a very uniform surface and an extremely smooth surface by a chemical vapor deposition method.