JP2003139897A - Ultraviolet irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet irradiation device capable of detecting even small leakage of cooling water with good reaction and preventing minimum the leakage into a lamp house. SOLUTION: To the ultraviolet irradiation device, a lamp irradiating ultraviolet, a lamp house containing the lamp and a pipe introducing water for cooling into the lamp house are provided. A pressure switch for detecting pressure inside the lamp house is provided. Also, a water sensor is provided in the lamp house of the ultraviolet irradiation device. Furthermore, a control means for detecting water leak from at least one of the pressure switch or the water sensor and stopping water introduction is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet irradiation device using a dielectric barrier discharge lamp, and more particularly to an ultraviolet irradiation device equipped with a water cooling mechanism.

[0002]

2. Description of the Related Art Recently, a technique of irradiating an object to be treated such as metal or glass with ultraviolet rays in the air to treat the object to be treated by the action of the ultraviolet rays and ozone generated thereby, for example, the object A cleaning treatment technology for removing organic contaminants adhering to the surface of, and an oxide film formation treatment technology for forming an oxide film on the surface of an object to be treated have been developed and put to practical use.

An ultraviolet irradiation device or an ultraviolet processing device for performing such ultraviolet processing is provided with a lamp that emits ultraviolet light, and in recent years, excimer light irradiation has been provided with an ultraviolet dielectric barrier discharge lamp as an ultraviolet source. The device has been developed and is widely applied in the fields of the semiconductor industry and the liquid crystal industry, such as dry cleaning of organic contaminants on the surface of a work, surface modification and ashing. For example, in dry cleaning, a simple method is to irradiate a substrate placed in the atmosphere with vacuum ultraviolet light, and it is possible to achieve highly efficient processing compared to the conventionally known ultraviolet cleaning using a low-pressure mercury lamp. it can.

As an example of the ultraviolet irradiation device, for example, in Japanese Patent No. 2789557, a dielectric barrier discharge lamp is provided with a cooling block attached to the lamp, and the cooling block is cooled by a cooling fluid. , An ultraviolet irradiation device for cooling a main dielectric barrier discharge lamp is described. Further, the one described in Japanese Patent No. 2528244 describes an ultraviolet irradiation device including an excimer generation source that directly cools a part of the excimer generation source main body with a cooling fluid.

The effect of cooling the ultraviolet light source such as the dielectric barrier discharge lamp is to suppress the temperature rise of the discharge gas, which suppresses the decrease of the excimer molecule formation efficiency and thus the ultraviolet light generation efficiency. It is to raise. The ultraviolet irradiation devices described in the above two publications are for cooling by circulating a cooling fluid in the device,
Water is preferably used as the cooling fluid.

[0006]

By the way, in the above-mentioned ultraviolet irradiating device, due to the structure of circulating water in the ultraviolet irradiating device, a water inlet / outlet pipe is arranged inside the lamp house in the lamp house. , A joint that connects this pipe and the water flow path will be attached if necessary. Water may leak from such joints, and measures against water leakage are necessary just in case.

Since water leaking into the lamp house is stored in the lamp house in a substantially sealed state, it suffices to stop the water supply to the extent that the internal volume of the lamp house is not exceeded. However, if water is supplied in excess of the internal volume of the lamp house, it will leak to the outside and cause a serious accident. Also, if a large amount of water enters the lamp house, it takes a lot of time and effort to bring the device into a usable state as usual. For this reason, it is necessary to minimize the water leak in the lamp house, and it is necessary to detect the water leak at the initial stage of the water leak.

The present invention has been made based on the above circumstances, and an object thereof is to detect reactivity of even a slight leak of cooling water and minimize water leak into the lamp house. An object of the present invention is to provide an ultraviolet irradiation device which can be prevented as much as possible.

[0009]

An ultraviolet irradiating device of the present invention comprises a lamp for radiating ultraviolet rays, a lamp house in which the lamp is housed, and a pipe for introducing cooling water into the lamp house. A pressure switch for detecting the pressure inside the lamp house is provided. Further, a water sensor may be provided in the lamp house of the ultraviolet irradiation device. In addition, control means may be provided for detecting the water leakage from at least one of the pressure switch and the water sensor and stopping the introduction of the water.

[0010]

In the lamp house, nitrogen is filled to preferably transmit vacuum ultraviolet light. At the time of normal lighting, since ultraviolet rays are generated in the storage room,
If water enters the storage room, it will be in the gas or liquid state (H
₂ O) reacts with ultraviolet rays to dissociate into gaseous H ₂ and O, and fills the storage chamber. At this time, the pressure in the storage chamber becomes high at one time. If the pressure in the storage chamber is measured by a pressure gauge, it can be used as a means for detecting water leakage in the storage chamber by reading the pressure change.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory sectional view showing the structure of an example of the ultraviolet irradiation apparatus of the present invention. This ultraviolet irradiation device includes a plurality (four in the illustrated example) of dielectric barrier discharge lamps 20, and the dielectric barrier discharge lamps 2.
It is provided with a lamp housing 10 having a rectangular box shape, for example, which forms a lamp housing chamber R in which 0 is housed.

The lamp house 10 includes a box-shaped frame member 11 having an opening 12 on the lower surface and a rectangular shape, and a dielectric barrier discharge lamp 20 provided so as to hermetically close the opening 12 of the frame member 11. A window member 13 for emitting vacuum ultraviolet rays to the outside of the lamp housing chamber R. Further, a gas introduction hole 14 for introducing an inert gas into the lamp storage chamber R is formed on one side surface of the frame member 11, and the other side surface of the frame member 11 is provided with a gas introduction hole 14. A gas discharge hole 15 for discharging gas is formed.

The window member 13 is made of a material having a transparency to ultraviolet rays, for example, a wavelength of 200 nm.
The following synthetic quartz glass having transparency to vacuum ultraviolet rays can be used.

In the dielectric barrier discharge lamp 20,
As shown in FIG. 2, one cylindrical wall member 21 made of a dielectric material and smaller than the inner diameter of the one wall member 21 arranged along the cylinder axis in the one wall member 21. A discharge vessel 23 having the other wall material 22 made of a dielectric material having an outer diameter is provided. In this discharge container 23, both ends of one wall member 21 and the other wall member 22 are joined by a sealing wall unit 24, and a cylindrical shape is formed between one wall member 21 and the other wall member 22. Discharge space S is formed.

One wall member 21 of the discharge vessel 23 is provided with one mesh-like electrode 26 made of a conductive material such as a wire mesh in close contact with the outer peripheral surface 25 thereof, and the other wall of the discharge vessel 23. The material 22 is provided with the other film-shaped electrode 28 made of aluminum so as to cover the outer surface 27 thereof. The one electrode 26 and the other electrode 28 are connected to an appropriate power supply device (not shown) by a cord 29 for supplying current.

As the dielectric material forming the one wall member 21 and the other wall member 22 in the discharge vessel 23, for example, synthetic quartz glass having a transparency to vacuum ultraviolet rays having a wavelength of 200 nm or less can be used.

The discharge vessel 23 is filled with, for example, xenon gas or a mixed gas of argon and chlorine as a discharge gas and radiates vacuum ultraviolet rays having a wavelength of 200 nm or less. The discharge gas is preferably filled so that the product pd of the distance d (mm) of the discharge gap of the discharge space S in the discharge vessel 23 and the pressure p (kPa) of the discharge gas is 80 to 500. . By filling the discharge gas under such conditions, excimer light in the vacuum ultraviolet region can be obtained with high efficiency. When a high frequency voltage is applied between the one electrode 26 and the other electrode 28 of the dielectric barrier discharge lamp 20, a dielectric barrier discharge is generated in the discharge space S in the discharge container 23, which causes
Excimer is generated by the elements that make up the filling gas,
Excimer light in the vacuum ultraviolet region due to the excimer is emitted from the mesh of the one electrode 26 through the one wall member 21. Specifically, when xenon gas is used as the discharge gas, vacuum ultraviolet rays having a peak at a wavelength of 172 nm due to the xenon excimer are emitted, and when a mixed gas of argon and chlorine is used as the discharge gas, argon is used. -Vacuum ultraviolet rays having a peak at a wavelength of 175 nm due to chlorine excimer are emitted.

The vacuum ultraviolet rays radiated from the dielectric barrier discharge lamp 20 are radiated to the outside of the lamp housing R through the window member 13. Here, since the lamp storage chamber R is filled with nitrogen gas, vacuum ultraviolet rays from the dielectric barrier discharge lamp 20 are not absorbed in the lamp storage chamber R. An object to be processed W such as a Cr substrate or a silicon wafer used in a liquid crystal manufacturing process is arranged immediately below the window member 11, and the object to be processed W is irradiated with the vacuum ultraviolet light transmitted through the window member 13. Will be. When the atmosphere in the lamp storage chamber R is air, most of the vacuum ultraviolet rays from the dielectric barrier discharge lamp 20 are absorbed by the air, and it becomes impossible to emit vacuum ultraviolet rays having a large output to the outside. .

A cooling block 30 made of aluminum is provided in the upper part of the lamp house 10. On the lower surface of the cooling block 30, four grooves 31 each having a semicircular cross section, each having a diameter larger than the outer diameter of the dielectric barrier discharge lamp 20, are formed so as to be spaced apart from each other. A dielectric barrier discharge lamp 20 is arranged along each of the above.

A through hole is provided in the cooling block 30, and a cooling water flow passage 32 is formed by inserting, for example, a pipe material for circulating cooling water. A cooling water introduction pipe 34 is connected to one end of the cooling water distribution pipe 32 via a joint 33, and one end of the cooling water flow pipe 32 is also connected to a cooling water discharge pipe 36 via a joint 35. ing.

The cooling water introduction pipe 34 and the cooling water discharge pipe 36 penetrate the frame member 11 of the lamp house 10 and have outer ends projecting to the outside of the storage chamber R. Connected to the water pipe.

In the above-mentioned ultraviolet irradiation device, for example, nitrogen gas is introduced into the lamp housing chamber R from the gas introduction hole 14 so that the inside of the lamp housing chamber R is filled with nitrogen gas. The pressure in the storage chamber R is, for example, 300 Pa in gauge pressure.

The frame member 11 of the lamp house 10 is provided with a pressure switch 40 having a pressure measuring means for measuring the pressure inside the lamp house 10 and a transmitting means for transmitting an abnormal signal when a predetermined pressure reference is reached. Installed. The pressure switch 40 is composed of, for example, a slight differential pressure switch or the like.
It can be detected on the order of several to several tens of Pa based on the difference from the internal pressure. The pressure switch 40 determines that there is water leakage when the internal pressure of the lamp house 10 rises above a predetermined reference value, for example, and sends an abnormality signal to the control unit 41. Control unit 4
1 receives an abnormal signal from the pressure switch 40,
In the solenoid valve 42 attached to the cooling water introduction pipe 34 described above,
Send a stop signal to shut off the introduction of cooling water. Then, the solenoid valve 42 is closed and the supply of cooling water is stopped. Further, the pressure switch 40 may be provided with an alarm function. The criteria for water leakage in the pressure switch 40 can be appropriately set depending on the relationship with the internal pressure of the lamp house 10 at normal times. For example, the difference in pressure increased within a unit time may be measured, and an abnormal signal may be transmitted when the pressure rises above a reference value within a unit time. Depending on the specifications of the ultraviolet irradiation device, there is a case where nitrogen lamp is used while flowing through the lamp housing chamber R, and therefore the internal pressure may be suddenly changed by the nitrogen gas. In such a case, a flow meter or the like (not shown) capable of monitoring the flow rate change of the nitrogen gas may be attached to the gas inlet 14 and the gas outlet 15 so that the pressure switch 40 does not detect the pressure change due to the nitrogen gas. In addition to the pressure switch 40, a pressure gauge (not shown) capable of monitoring changes in internal pressure due to nitrogen gas may be attached.

The present inventors conducted the following experiment and confirmed that the presence of water in the lamp house can be detected based on the pressure in the lamp house. That is,
Inside the lamp house, a container containing about 10 cc of water was placed in a place where it was not directly irradiated with ultraviolet light, and the lamp was turned on. The internal pressure before the lamp was turned on was about 300P initially.
It was confirmed that the pressure of a was increased to about 500 Pa after irradiation time of about 1 s. This is because a small amount of water introduced into the lamp house partially becomes water vapor and floats, and when the water vapor is irradiated with ultraviolet rays, the water molecules (H ₂ O) temporarily change. It is presumed that the internal pressure increased as a result of dissociation into H ₂ and O. Regarding the dissociation reaction of H ₂ O by ultraviolet irradiation, a similar report was made in the presentation of "Gas release characteristics of quartz glass by UV irradiation" by Toyonane et al. In this way, it has been confirmed that the internal pressure of the lamp house rises sharply even with an extremely small amount of water, so if a water leak occurs by monitoring the pressure inside the lamp house using a pressure switch. This makes it possible to detect this accurately and instantly. Therefore, it is possible to respond in a very short time from the occurrence of water leakage until the supply of the cooling water is stopped, and it is possible to minimize the water leakage into the lamp house.

Referring again to FIG. 1, a further embodiment of the invention will be described. As shown in the figure, a pan 43 for receiving water is installed at a position corresponding to the piping of the cooling water and not blocking the light from the light extraction window 13, and the pan 43 has a water sensor 44. Are arranged. Water sensor
Specifically, it is a leak sensor, and for example, LSP-8A-0 manufactured by T & T can be used. Bread 43
1 is installed on the floor surface of the lamp house 10 with a slight inclination when viewed from the side as shown in FIG. 1, and when water flows down along the inclination, the water is placed on the lower portion 43a of the pan 43. The detected water sensor 44 detects this and detects water leakage.
In this way, when the pan 43 is tilted and arranged in the lamp house 10, even a small amount of water leak can be reliably detected without disposing a large number of water sensors 44.

The water sensor 44 is connected to, for example, the control unit 41. When the water sensor 44 detects water, it sends an abnormal signal to the control unit 41, and the control unit 41 blocks the electromagnetic valve 42. Send a signal. When the water leak is detected only by the pressure switch (40) described above, no abnormal increase in the internal pressure of the lamp house 10 occurs because the ultraviolet light is not generated when the lamp is not lit, and the water leak cannot be detected. However, as in the present embodiment, by installing the water sensor 44 in addition to the pressure switch (40), it becomes possible to detect water leakage even when the ultraviolet irradiation device is not in use, and the lamp house 10 can be detected. It is possible to constantly detect water leakage inside.

Of course, when the lamp is not lit, that is, when the ultraviolet irradiation device is not used, the flow of cooling water is normally stopped, so that a large amount of water is unlikely to leak out. However,
Even in such a case, there is an advantage that the looseness of the joint portion can be detected in advance, and in this case, it becomes possible to prevent water leakage in advance.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned ultraviolet irradiation device, and various modifications can be added. For example, the method of cooling the lamp is not limited to the method of cooling the lamp by using a cooling block through which water flows, and a part of the dielectric material that constitutes the lamp is formed into a circular tube shape to directly cool the water. Alternatively, a method of circulating and cooling may be used.

[0029]

As described above, according to the present invention, since the pressure switch for monitoring the internal pressure of the lamp house is provided, when water leak occurs in the lamp house, the internal pressure is changed by changing the internal pressure. It becomes possible to detect,
It is possible to reliably detect even a very small amount of water leakage.

Further, since the supply of the cooling water is stopped based on the water leak detection signal from the pressure switch, it becomes possible to stop the supply of the cooling water immediately after the occurrence of the water leak, and the lamp house. Water leakage into the interior can be minimized. Therefore, it is possible to prevent an accident in which water leaks out of the lamp house.

Further, by disposing the water sensor in the lamp house, it becomes possible to monitor water leakage even when the lamp is not lit.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing a configuration of an example of an ultraviolet irradiation device of the present invention.

FIG. 2 is a sectional view for explaining a dielectric barrier discharge lamp.

[Explanation of symbols]

10 lamp house 11 Frame material 12 openings 13 Window member 14 gas inlet 15 gas outlet 20 Dielectric barrier discharge lamp 21 One wall material 22 Other wall material 23 Discharge container 24 Sealing wall 25 outer peripheral surface 26 One electrode 27 exterior 28 Other electrode 29 codes 30 cooling blocks 31 groove 32 Cooling water flow passage 33 Joint 34 Cooling water introduction pipe 35 Joint 36 Cooling water discharge pipe 40 pressure switch 41 Control unit 42 Solenoid valve 43 bread 44 Water sensor

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3B116 AA01 BC01 CD41 CD43                 4G075 AA24 AA30 AA61 AA65 BA05                       BA06 BB10 BC10 CA03 CA33                       DA02 EB32 FB06

Claims (3)

[Claims] 1. A lamp that emits ultraviolet rays, a lamp house that houses the lamp, and a pipe that introduces cooling water into the lamp house are provided, and the pressure inside the lamp house is detected. An ultraviolet irradiation device characterized in that a pressure switch is provided. 2. The ultraviolet irradiation device according to claim 1, wherein a water sensor is provided in the lamp house. 3. A control means for detecting water leakage from at least one of the pressure switch and the water sensor and stopping the introduction of water is provided.
Or the ultraviolet irradiation device according to 2.