JPH09106783A - Excimer discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excimer discharge lamp which has a self-supply function of a halogen gas and outputs stable excimer light at all times. SOLUTION: A mixed gas for generating excimer light is enclosed in a main discharge space having a pair of electrodes 11, and spontaneous emission light is taken out of excimer molecules by causing the mixed gas to electrically discharge. A branch tube 3 forming a discharge path other than a main discharge path is provided and linked to the main discharge space and the branch tube 3 is equipped with an electrode, which causes dielectric barrier discharge to occur with the branch tube 3 acting as a dielectric and is disposed on an outer surface thereof, and a light emitting element supplying substance 4 composed of a halogen compound which is solid state at room temperatures is located therewithin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excimer discharge lamp which contains a rare gas and a halogen gas therein and takes out spontaneous emission light from an excimer generated by discharging this mixed gas.

[0002]

2. Description of the Related Art In recent years, in order to efficiently generate ultraviolet rays (UV) and vacuum ultraviolet rays (VUV) like excimer lasers, light sources utilizing excimers have been actively developed. Here, the excimer is an abbreviation for Excited Dimer and refers to an excited state polyatomic molecule.There are several types, but the main ones are rare gas excimer and rare gas.
There is a halide excimer. Of these, rare gas excimers include Xe ₂ and Ar ₂ , and rare gas excimers include XeCl ^* and KrF ^* . Particularly, in the rare gas / halide excimer, the light output of excimer light changes depending on the ratio of the halogen gas and the rare gas, so it is important to set the ratio of the halogen gas with the best output.

The rare gas / halide excimer laser is one in which a mixed gas of a rare gas and a halogen gas is sealed at several atmospheres, an excimer is produced from this mixed gas by glow discharge, and laser emission is caused by stimulated emission of the excimer. Since this excimer laser utilizes the excimer state of a rare gas and a halogen gas, the halogen gas is reduced over time due to a chemical reaction and adhesion with the inner wall of the laser tube and the surface of the components inside the laser tube. Will end up. This decrease in halogen gas causes a decrease in the output of excimer light, so
In order to maintain a constant light output, means for replenishing the reduced halogen gas is needed. For example, JP-A-62-10938
In 0, a technique is disclosed in which a halogen adsorbent that releases a halogen gas when heated to a certain temperature or higher is sealed in advance. Further, Japanese Patent Laid-Open No. 1-115182 proposes a method of photo-decomposing a metal halide such as silver chloride (AgCl) to generate a halogen gas and supplying the halogen gas. However, such a technique cannot provide sufficient halogen gas replenishment, and requires a heating means, resulting in a complicated apparatus as a whole.

On the other hand, ultraviolet rays (UV) and vacuum ultraviolet rays (VU)
As a means for efficiently generating V), an excimer discharge lamp utilizing spontaneous emission light of excimer has been proposed.
This excimer discharge lamp takes out spontaneous emission light from excimer molecules without causing laser oscillation after the enclosed gas is made into an excimer state.
No. 36 disclosed.

An excimer lamp has a pair of electrodes inside and is of a pulsed type (T. Gerber et al, Op.
t.Commun. 35,242 (1981)) and continuous operation (RS Taylo
r et al, Appl. Phys. Lett. 59 (5), 525 (1991)) have been reported. Of these, pulse operation is, for example, Kr
The peak power is 400 kW and the luminous efficiency is 28% in the case of the F-sealed lamp, while Xe is
In the case of a Cl-encapsulated lamp, the peak power is 6 W and the luminous efficiency is about 1%. In other words, the pulsed excimer lamp can obtain excimer light of higher power, and has a possibility of new industrial application as a high-power ultraviolet light source next to the excimer laser.

On the other hand, as mentioned above, a means for replenishing the halogen gas is required, and in general, a method of supplying from an external cylinder has been proposed. This is to prevent halogen gas from reacting with the electrode material and exhausting halogen gas as a result of being supplied from the outside, but with such a method, there is also toxicity of halogen gas. There is a problem in preparing gas piping equipment. To show the supply from such a cylinder,
(RS Taylor et al, Appl. Phys. Lett. 59 (5), 525 (19
91))

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an excimer discharge lamp having a halogen gas self-sufficiency function and capable of constantly outputting stable excimer light.

[0008]

In the excimer discharge lamp according to the present invention, excimer molecules are discharged by discharging a mixed gas from a main discharge space having a pair of electrodes, the mixed gas generating excimer being enclosed. The main discharge space is provided with a branch pipe that forms a discharge path different from the main discharge path, and the branch tube is formed on the outer surface of the branch tube. An electrode for inducing a dielectric barrier discharge is disposed as a body, and a light emitting element supplying substance made of a halogen compound which is solid at room temperature is disposed inside the electrode. This is because a dielectric barrier discharge is generated between one of the electrodes for main discharge and the dielectric barrier discharge electrode arranged in the branch tube, and it is arranged in advance by the emitted light. A light emitting element supply material composed of a halogen compound which is solid at room temperature is photolyzed and supplied as halogen gas to the main discharge space.

Further, as another structure, a branch pipe is connected to the main discharge space, a dielectric barrier discharge means is connected to the main discharge space, and a halogen compound which is solid at room temperature is provided inside the branch pipe. And a means for supplying the light emitting element supplying substance to the main discharge space by photolyzing the light emitting element supplying substance by the dielectric barrier discharge. This is to have a dielectric barrier discharge means separately from the main discharge electrode, and photolytically decompose the luminescent element supply substance by the emitted light by this dielectric barrier discharge to supply it as a halogen gas to the main discharge space. Is.
H.

Further, in the above two configurations, the main discharge is performed by a pulse operation. This is because the pulsed lighting produces better excimer light output than continuous lighting.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a circuit diagram for causing a discharge tube 1 to emit light. The discharge circuit is a general pulse discharge circuit,
The capacitor C is charged from the power source 2 through the resistors R1 and R2, and the spark gap switch S is applied to apply a high voltage to the discharge tube 1. Here, as the capacitor C, for example, a 200pF ceramic capacitor is applied, and −14k
The V voltage is charged.

The discharge tube 1 is composed of a fused silica tube, and tungsten electrodes 11 are arranged inside both ends thereof. Here, as an example, the inner diameter of the discharge tube 1 is 8 mm, and the electrode 11
Has a diameter of 5 mm and the distance between the electrodes is 100 mm. A mixed gas of xenon and neon is enclosed in the discharge tube 1 as an enclosed gas. The mixing ratio is, for example, 20:80, and the filling pressure is 50 Torr. Of these, neon is added to stably generate glow discharge. Further, as will be described later, by providing a replenishing means for the halogen gas, it is possible not to enclose the halogen gas at the start of lighting the lamp. Then, the discharge tube 1 emits strong ultraviolet rays having a peak at a wavelength of 308 nm.
Further, the emitted light is emitted for a very short period of about 200 ns.

A branch tube 3 is attached to the discharge tube 1. This branch pipe 3 has, for example, an inner diameter of 2 mm, an outer diameter of 4 mm, and a length of 40.
mm quartz tube, for example, discharge tube 1 as shown
It can be attached by welding almost vertically. A halogen compound, which is solid at room temperature, is disposed as a light emitting element supply material 4 at an end of the branch tube 3 opposite to the discharge tube 1. This halogen compound is, for example, silver chloride (AgCl) of about 30
mg is placed, but other than that, fluorine chloride (AgF)
It is also possible to arrange such as in relation to the filling gas of the discharge tube 1.

A portion of the outer surface of the branch pipe 3 that substantially corresponds to the position where the light emitting element supply material 4 is disposed inside,
As one electrode for the dielectric barrier discharge, for example, a metal foil 5 such as an aluminum foil is wound, and this is used as an external electrode.
Dielectric barrier discharge occurs between this electrode and one of the main discharge electrodes 11. The metal foil 5 and the main discharge electrode 11
AC high voltage from power supply 2 during, for example 8KV frequency 2
0 KHz is applied. Further, it is effective to dispose the halide as close to the dielectric barrier discharge electrode as possible in view of the decomposition efficiency of the halide. However, even if a halide is placed between the dielectric barrier discharge electrode and the main discharge electrode, the metal halide is decomposed.

Here, the dielectric barrier discharge refers to a discharge that occurs when a discharge gas that forms excimer molecules fills the discharge space, a dielectric layer is interposed in the discharge path, and an AC voltage is applied to the gap. , Revised edition (Discharge Handbook), published by the Institute of Electrical Engineers of Japan, June 1989, 7th edition, published on page 263. And, because the dielectric material is made of quartz glass or the like, the arc discharge is suppressed by interposing it in the discharge path, and since the discharge is not concentrated at a specific place, the density of the generated ultraviolet rays is almost uniform. You can In the present invention, the main discharge space and the branch tube form a discharge path different from the main discharge path, and a dielectric barrier discharge is generated by using a part of the branch tube as a dielectric. It was decided to photolyze a metal halide such as silver chloride with vacuum ultraviolet light (for example, 172 nm) generated by this discharge. When such a metal halide is photolyzed at room temperature, the generated halogen gas is chemically pure, the metal vapor is at a negligible level, and the dielectric barrier discharge is generated depending on the discharge time. The amount of halogen gas can be controlled.

Next, an experiment showing the effect of the present invention will be described with reference to FIG. From the state where the enclosed amount of halogen gas was set to the amount that radiates excimer light most efficiently, the dielectric barrier discharge was stopped, and the discharge tube was made to emit light without being supplemented with halogen gas. The discharge tube was pulsed at 10 Hz. In FIG. 2, the horizontal axis represents the number of times of lighting, and the vertical axis represents the relative value with the initial value of the optical output having a wavelength of 308 nm. From the figure, it can be seen that the light output at the wavelength of 308 nm decreases as the number of times of lighting increases, and decreases to about half of the initial value after 10 ⁶ times of lighting. When a dielectric barrier discharge is generated in this state, the optical output with a wavelength of 308 nm again rises to the same value as the initial value. This is because the halogen gas is sufficiently replenished. Wavelength 30
Halogen gas can be replenished by generating a dielectric barrier discharge according to the decrease of the light output of 8 nm, and the life of the lamp can be sufficiently extended.

In order to increase the supply amount of the halogen gas, the branch pipe for supplying the halogen gas may be enlarged and separated from the main discharge space. FIG. 3 shows a specific example. The dielectric barrier discharge means as a halogen gas generating tube is a double cylinder having an inner tube 12 and an outer tube 13, and metal electrodes 14 and 15 are provided on the inner surface of the inner tube 12 and the outer surface of the outer tube 13. A close contact is made, and a high AC voltage is applied between these electrodes by a power source 16 to generate a dielectric barrier discharge. A light emitting element supply material 17 is disposed between the inner tube 12 and the outer tube 13. Then, in order to prevent discharge between the main electrode 18 of the discharge tube 6 and the barrier discharge electrode, the discharge tube 1 and the halogen gas generation tube may be separated by the valve 20.

In this embodiment, the case where the discharge tube is pulsed to light the flash is described.
It goes without saying that the discharge tube may be continuously operated and continuously lit.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an apparatus used to carry out the present invention.

FIG. 2 is a diagram showing the relationship between the excimer light output and the number of lightings.

FIG. 3 is a conceptual diagram of a double cylinder type halogen gas supply pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge tube 2 Power supply 3 Branch tube 4 Luminous element supply material 5 Dielectric barrier discharge electrode 11 Main electrode

Claims (3)

[Claims] 1. An excimer discharge lamp for extracting spontaneous emission light from excimer molecules by discharging a mixed gas for generating an excimer from a state where a mixed gas for generating an excimer is enclosed in a main discharge space having a pair of electrodes, In the main discharge space, a branch pipe that forms a discharge path different from the main discharge path is continuously provided, and one of the pair of electrodes is formed on the outer surface of the branch tube by using the branch pipe as a dielectric. An electrode for inducing a dielectric barrier discharge is disposed in the other discharge path between the electrode and one of the electrodes, and a light emitting element supply material made of a halogen compound that is solid at room temperature is disposed inside the electrode. Excimer discharge lamp. 2. An excimer discharge lamp for extracting spontaneous emission light from excimer molecules by discharging a gas mixture containing an excimer from a state in which a gas mixture producing an excimer is enclosed in a main discharge space having a pair of electrodes, A branch tube is connected to the main discharge space, a dielectric barrier discharge means is connected to the branch tube, and a light emitting element supply material made of a halogen compound that is solid at room temperature is placed inside the branch tube. Further, the excimer discharge lamp is provided with a means for photo-decomposing the light emitting element supplying substance into the main discharge space by the dielectric barrier discharge. 3. The main discharge according to claim 1, wherein the main discharge by the pair of electrodes is performed by a pulse operation.
Excimer discharge lamp described.