JPH0568062B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a short wavelength ultraviolet light generator, in particular, high-quality α-Si using SiH ₄ gas using light energy with a wavelength of 120 nm to 190 nm: Generation of H thin films, application to optical devices, and applications in ultra-high vacuum containers.
This field concerns ultra-high vacuum technology based on the decomposition and separation of H ₂ O molecules, materials based on substances and their interactions, and the development of fundamental technologies such as life science.

[Conventional technology]

Microwave discharge has been variously studied as a form of electric discharge. This discharge is an electrodeless discharge and has characteristics not found in electroded discharges, such as energy being injected from the periphery of the discharge tube, and is characterized by the following points.

(1) Media freedom: The plasma generation medium can be freely selected without considering the reaction with the electrode, and there is no plasma contamination.

(2) Long life: There is no deterioration of the discharge tube due to scattering of electrode materials.

(3) Spreading of discharge: The discharge is not concentrated in one area and spreads easily, and the light emission is strong near the wall of the discharge tube.

(4) Simple configuration: The discharge tube has no electrodes, and no discharge stabilization element is required in the power supply.

Various vacuum ultraviolet light sources using microwave discharge that take advantage of these characteristics have been proposed.

For example, Japanese Patent Publication No. 55-35825 (U.S. Patent
As disclosed in USP No. 390659), there is a technology that confines microwaves in a certain space and confines a desired gas or metal in a quartz bulb, which is high melting point glass, to emit light (see Figure 6). reference).

Also, IEEE, 1987 MATUNAMI, FUYUKI
Like the vacuum ultraviolet light source published in the paper,
A quartz gas discharge tube 42 is placed on the H side of the rectangular waveguide 41 (see FIG. 7), and a rare gas GAS is caused to flow in the axial direction of the discharge tube 42 to cause a discharge. There is also a technique for extracting light energy with a wavelength of around 140 nm by providing a short wavelength transmitting window material 45 such as magnesium fluoride (MgF ₂ ).

Furthermore, P11 to P17 of Illuminating Society of Japan Study Group LS-87-1
As in the ``vacuum ultraviolet light source using microwave discharge'' announced in There is also a technology that allows the radiation to be placed in the same direction and extracts the entire emitted light.

[Problem to be solved by the invention]

By the way, since the plasma light emitting light source device disclosed in Japanese Patent Publication No. 55-35825 uses a quartz material as the arc tube 32, light with a wavelength below the short wavelength transmission limit of the quartz material (approximately 160 nm for synthetic quartz) cannot be used. There was a problem that it was not possible to take out the

Also, IEEE, 1987 MATUNAMI, FUYUKI
In the vacuum ultraviolet light source published in the paper, the plasma region changes depending on the microwave power. For this reason, it is difficult to increase the plasma power density, and it is also difficult to increase the area, and in practice it is difficult to increase the plasma power density.
It becomes about 30mm. Another problem was that the window material deteriorated quickly due to the use of plasma discharge.

Furthermore, P11 to P17 of Illuminating Society of Japan Study Group LS-87-1
The "vacuum ultraviolet light source using microwave discharge" announced in There was a limit, and the limit was 100W for microwave power.

From the above, it is an object of the present invention to have a window material that enables light irradiation over a large area with a diameter of 80 mm or more, to prevent deterioration of the window material, and to allow discharge gas to always flow at a constant pressure and flow rate. Therefore, by providing a short-wavelength ultraviolet light generator that prevents temperature rise due to discharge of discharge gas, extracts spectral lines with a constant radiation intensity and wavelength, and makes it possible to input high-power microwave power. be.

[Means and actions for solving the problem]

In order to solve the above problems, the short wavelength ultraviolet light generator of the present invention has a waveguide section 1, as shown in FIG.
The waveguide section 1 is separated and sealed from the atmosphere on the side of the waveguide section 1.
and a high vacuum section 2 having a high-resistance vacuum layer; an antenna section 3 located within the high vacuum section 2 that radiates microwaves 8 from the waveguide section 1 side; and an antenna section 3 adjacent to the high vacuum section 2. There is a gas discharge space 5 in which a discharge gas that emits light in response to microwaves 8 is sealed from the gas discharge nozzle 4, and a boundary between this gas discharge space 5 and the high vacuum section 2, which emits light in response to microwaves. A glass partition wall 6 made of a glass material that is transparent to the light beams 8 and impermeable to the discharge gas, and a short wavelength light beam 9 on the opposite side between the glass partition wall 6 and the gas discharge space 5. It has a short wavelength light transmitting window material 7 that emits a short wavelength light, and the microwave 8 transmitted through the glass partition wall 6 is connected to the discharge gas at a position near the glass partition wall 6 side in the gas discharge space 5 where the microwave 8 discharges and emits light. A discharge nozzle 4 was provided.

As a result, non-uniformity of the discharge light emission 9 due to the distribution of microwaves can be prevented, and the irradiation light distribution on the irradiated surface becomes uniform over a larger area. In addition, since the gas discharge nozzle 4 is installed at an appropriate position, the discharge is not performed on the high vacuum section 2 side, but on the space section 5 side where the gas is released, and moreover, on the glass partition wall 6 side, which is sufficiently resistant to gas discharge energy. It is possible to cause discharge light emission in a close space, and it is possible to prevent deterioration of the short wavelength transmission window material 7 due to discharge.

〔Example〕

Hereinafter, the short wavelength ultraviolet light generating device of the present invention will be explained based on the drawings.

FIG. 2 is a schematic explanatory diagram of a short wavelength ultraviolet light generating device which is an embodiment of the present invention.

11 is a microwave generator (magnetron), 1
2 is a circulator, 13 is a power monitor, 1
4 is a three-stub tuner, 15 is a waveguide exchanger that converts a rectangular waveguide into a circular waveguide, and 16 is a waveguide exchanger.
Gas cylinder for supplying gas for the discharge tube section (gas discharge space section) such as Xe, An, D ₂ , He, etc., 17a, 1
7b is an exhaust port, and 18 is a gas flow controller (MFC).

In magnetron 11, for example, 2450MHz
microwaves are generated and fed to the waveguide exchanger 15 through the rectangular waveguide. magnetron 11
Since it is operated by a full-wave rectified power supply, the microwaves generated are pulsating at 100Hz or 120Hz.

FIG. 3 is an explanatory diagram of the main parts of this short wavelength ultraviolet light generator. In addition, in FIG. 3, a high vacuum section 2, a microwave radiation antenna 3, a gas discharge nozzle 4, a gas discharge space section 5, a quartz glass partition wall 6, a short wavelength light transmission window material 7, a radiation electromagnetic field (microwave) 8, The same symbols as in FIG. 1 are used for the vacuum ultraviolet light 9 and the ceramic window 10. In addition, exhaust ports 17a, 17
The same reference numerals as in FIG. 2 are used for b.

Cooling water ports 21a and 21b cool the heat generated by light emission. 23 is a discharge gas supply port, 24
is a stainless steel arc tube holder.

Note that when microwave discharge is applied to a light source, it is necessary to use a short wavelength light transmitting window material 7 in the portion where light is extracted from the discharge. In this embodiment, for example,
An electrodeless discharge tube is formed using a magnesium fluoride (MgF ₂ ) window material 7. When this magnesium fluoride is used, the light transmission characteristic of the short wavelength light transmission window material 7 can transmit up to around 120 nm.

The high vacuum side of the high vacuum section 2 is preferably 10 ^-4 Torr or higher. At the level of 10 ^-1 to 10 ^-2 Torr, discharge occurs due to the residual atmosphere, the discharge electromagnetic field 8 is absorbed, and no effective discharge electromagnetic field 8 is supplied to the gas discharge space 5 side.

In this embodiment, the quartz glass partition wall 6 is substantially integrated with the short wavelength light transmitting window material 7, and also serves as the discharge tube section 5.

The gas discharge nozzle 4 is inserted into the discharge gas supply port 23 using quartz glass. By inserting the stainless steel arc tube holder 24, microwave discharge is prevented from occurring in the metal part of the stainless steel arc tube holder 24.

Further, the gas discharged from the gas discharge nozzle 4 is once blown to the side of the short wavelength light transmitting window material 7 to cool the short wavelength light transmitting window material 7, and then the gas is discharged from the exhaust port 17.
It is exhausted from b. Due to this gas circulation, the discharge can be emitted on the side of the space 5 where the gas is released, and also in the space close to the glass partition wall 6, which is sufficiently resistant to gas discharge energy, and short wavelength light can be transmitted by the discharge. Deterioration of the window material 7 can be prevented.

Next, the vacuum ultraviolet emission characteristics of the xenon (Xe) gas used in this example will be explained.

Xenon gas has a resonance line of 147 nm and is often used as a vacuum ultraviolet light source. The spectrum of the 147 nm line when the discharge tube section 5 of this example is used will be explained. FIG. 4 shows the profile of the 147 nm resonance line when xenon (99.995%) is used as the discharge gas and the discharge pressure is varied from 0.1 Torr to 10 Torr. The gas flow rate is 20c.c./min.
Discharge experiments were conducted at Pi=0.5Kw and Pr=0.05Kw.

In addition, ACTON VM− is used as a measurement spectrometer.
ACTON DA-780-VUV was used for 502. Furthermore,
At this time, the slit width is 0.25mm, and the slit length is 4
mm, the measurement distance is 69cm.

As shown in FIG. 4, the higher the pressure, the lower the peak of the spectrum. Since inversion absorption occurs at 10 Torr, it is thought that this is largely due to the influence of self-absorption.

Figure 5 is an illuminance distribution diagram when xenon gas is 0.85 Torr. In addition, in order to measure the illuminance distribution of this emission, we used 250nm when the xenon gas was 0.85Torr.
The luminescence intensity before and after was measured using an ultraviolet light meter manufactured by the applicant.
UV-M02 was used. Due to this illuminance distribution, the diameter is 80 mm.
As the intensity ratio in mm, Imin/Imax=9/12=0.75 could be obtained.

As a result, if the short wavelength ultraviolet light generator of the present invention is used, a practically sufficient intensity ratio can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the antenna part that radiates electromagnetic waves is sealed and separated from the atmospheric part of the waveguide part, and has a window material that enables light irradiation over a large area with a diameter of 80 mm or more, and This structure prevents the window material from deteriorating and allows the discharge gas to always flow at a constant pressure and flow rate, thereby preventing temperature rise due to discharge of the discharge gas.
Certain desired spectral lines can be extracted. That is, the emission wavelength can be selected by changing the type and pressure of the gas. Further, it becomes possible to input high-power microwave power.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of a short wavelength ultraviolet light generating device of the present invention, Fig. 2 is an overall view of a short wavelength ultraviolet light generating device which is an embodiment of the present invention, and Fig. 3 is a schematic diagram of the short wavelength ultraviolet light generating device of the present invention. An explanatory diagram of the main parts of the device, Fig. 4 is a profile of the 147 nm resonance line of xenon gas, Fig. 5 is an illuminance distribution diagram when xenon gas is 0.85 Torr, Fig. 6
8 are schematic illustrations of a conventional short wavelength ultraviolet light generator. DESCRIPTION OF SYMBOLS 1... Waveguide, 2... High vacuum part, 3... Antenna part, 4... Gas discharge nozzle, 5... Gas discharge space part, 6... Glass partition, 7... Short wavelength light transmission window material , 8...Microwave, 9...Discharge light emission, 11...
...Magnetron, 12...Circle Racer, 1
4...Three stable chamber, 19...Vacuum chamber.

Claims (1)

[Scope of Claims] 1. A waveguide portion and the atmosphere on the side of the waveguide portion are separated and sealed, and a high vacuum portion having a high-resistance vacuum layer; an antenna section that radiates microwaves from the wave tube section side; a gas discharge space section that is adjacent to the high vacuum section and is formed by sealing a discharge gas that emits light in response to the microwaves through a gas discharge nozzle; and this gas discharge space. transparent to microwaves, at the boundary between the part and the high vacuum part,
and a glass partition wall made of a glass material that is impermeable to the discharge gas, and a short-wavelength light-transmissive window material that emits short-wavelength light on the opposite side sandwiching the glass partition wall and the gas discharge space. The short-wavelength ultraviolet light generating device is characterized in that the gas discharge nozzle is disposed at a position where the microwave transmitted through the glass partition causes discharge light emission between the discharge gas and the vicinity of the glass partition in the gas discharge space. .