JP2004171889A - Excimer light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excimer light source device capable of providing high luminous efficiency as a whole even when lighting an excimer lamp by intermittently and repeatedly supplying highpass high frequency power with a frequency of ≥1MHz. <P>SOLUTION: The excimer light source device is provided with a plurality of excimer lamps, and a lighting electric power unit lighting the excimer lamps by intermittently supplying the high frequency power with the frequency of ≥1MHz. It is characterized by that the lighting electric power unit starts the supply of the high frequency power to one excimer lamp while the one excimer lamp is receiving ultraviolet rays from another excimer lamp. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an excimer light source device including a plurality of excimer lamps that are turned on by high-frequency power having a frequency of 1 MHz or higher, generate discharge by the high-frequency power, and emit ultraviolet rays emitted from excimer molecules by the discharge.
[0002]
[Prior art]
For example, in various processes such as a cleaning process of a surface of a processing target such as a semiconductor wafer or a glass substrate for a liquid crystal display device, a generation process of an ultra-thin oxide film on a surface of the processing target, and a curing process of an ultraviolet curable resin, Irradiation of an ultraviolet ray to an object to be processed is performed.
[0003]
For such ultraviolet irradiation treatment, for example, an excimer light source device is used. At present, as an excimer light source device, a cylindrical discharge vessel made of, for example, quartz glass filled with various excimer molecule generation gases, and a discharge space defined by the discharge vessel are provided. And a pair of electrodes disposed so as to face each other, generating an excimer molecule by applying a voltage between the pair of electrodes to generate a discharge, and utilizing ultraviolet light emission by the excimer molecule. A lamp having a plurality of excimer lamps is preferably used.
[0004]
Conventionally, such excimer lamps are lit by supplying low-frequency high-frequency power having a frequency of several tens of kHz, which requires a simple configuration in a required lighting circuit and lowers the required configuration. In the case of supplying power at a frequency, a high voltage of, for example, 10 kV or more is required to generate a discharge, which results in, for example, an insulation problem. This is because, when turned on, it is necessary to take measures against various electromagnetic interferences (EMI) for peripheral devices.
[0005]
However, since measures against electromagnetic interference (EMI) have been established in recent years, it has been proposed to turn on such excimer lamps by supplying high-frequency high-frequency power having a frequency of 1 MHz or more, for example. (For example, see Patent Documents 1 and 2).
This is because, when high-frequency high-frequency power having a frequency of 1 MHz or more is used, in an excimer lamp, the voltage required to cause discharge can be as low as about 1 to 3 kV. Because it is advantageous.
[0006]
However, when the excimer lamp is turned on by continuously supplying high-frequency high-frequency power having a frequency of 1 MHz or more, a high light emission output can be obtained immediately after the supply of the high-frequency high-frequency power is started. As the time elapses, the luminous output gradually decreases due to an increase in the temperature of the excimer gas or a decrease in the excimer molecule generation efficiency, which is higher than the overall power consumption. There is a problem that luminous efficiency cannot be obtained.
[0007]
In order to solve such a problem, a specification related to Japanese Patent Application No. 2002-256918 discloses an excimer lamp for lighting an excimer lamp by intermittently supplying high-frequency high-frequency power having a frequency of 1 MHz or more to the excimer lamp. A lamp lighting device is disclosed.
According to such an excimer lamp lighting device, it is possible to increase the power consumption per unit lighting time of the excimer lamp under the condition of the same power consumption as in the case of continuously supplying high frequency power. Moreover, there is an advantage that the luminescence output over time is prevented from being attenuated, and as a result, the luminous efficiency can be improved.
[0008]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-31658 [Patent Document 2]
Japanese Patent No. 3282804
[Problems to be solved by the invention]
In the excimer lamp lighting device disclosed in Japanese Patent Application No. 2002-256918, the impedance of the lighting circuit is made to match the impedance of the excimer lamp in the lighting state. This is for suppressing.
[0010]
However, since the impedance of the excimer lamp differs greatly between the lit state and the extinguished state in which no discharge occurs, a large reflected wave is generated when the high-frequency high-frequency power is supplied to the excimer lamp in the extinguished state. Therefore, for example, not only may the lighting power supply device be adversely affected, but the total loss energy due to the reflected wave becomes considerably large because the supply of the high-frequency high-frequency power is intermittently repeated. As a result, there is a problem that high luminous efficiency cannot be obtained.
[0011]
The present invention has been made in view of the above circumstances, and intermittently repeatedly supplies high-frequency high-frequency power having a frequency of 1 MHz or more (hereinafter, also simply referred to as “high-frequency high-frequency power”). An object of the present invention is to provide an excimer light source device capable of obtaining high luminous efficiency as a whole even when an excimer lamp is turned on.
[0012]
[Means for Solving the Problems]
An excimer light source device according to the present invention includes: a plurality of excimer lamps; and a lighting power supply device for lighting these excimer lamps by intermittently supplying high-frequency power having a frequency of 1 MHz or more. The apparatus is characterized in that the supply of high-frequency power to one excimer lamp is started while the one excimer lamp is receiving ultraviolet rays from another excimer lamp.
Here, the other excimer lamp is preferably disposed adjacent to the one excimer lamp.
[0013]
[Action]
In the excimer lamp, in the state where the ultraviolet light is irradiated, much better starting performance can be obtained than when the ultraviolet light is not irradiated. According to the excimer light source device of the present invention, The supply of high-frequency high-frequency power to the excimer lamp was started while the one excimer lamp was receiving ultraviolet rays radiated from the other excimer lamp, so that the supply of the high-frequency high-frequency power was started. The transition to the fully lit state in a very short time from the point in time reduces the time during which impedance matching has not been obtained with the lighting circuit, and therefore the energy loss due to reflected waves caused by impedance mismatching is sufficient. As a result, high luminous efficiency can be obtained in the excimer lamp.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
FIG. 1 is a cross-sectional view illustrating an example of a mechanical configuration of an excimer light source device. FIG. 2 is a cross-sectional view taken along a tube axis of an example of an excimer lamp provided in the excimer light source device. FIG. 3 is a block diagram schematically illustrating the configuration of the lighting circuit, and FIGS. 4A to 4D are high-frequency power, a modulation signal, a waveform related to modulated high-frequency power, and an excimer lamp, respectively. 4 is an explanatory drawing showing an example of light emission intensity in FIG.
[0015]
In FIG. 1, reference numeral 10 denotes a box-shaped lamp house, on the lower surface of which a light irradiation window 11 is provided. Inside the lamp house 10, a cooling block 12 made of, for example, aluminum is provided. On the lower surface of the cooling block 12, a plurality of (two in FIG. 1) grooves 121 each having a semicircular cross section are provided. Are formed in parallel with each other so as to extend in a direction perpendicular to the paper surface. In each of these grooves 121, a rod-shaped excimer lamp 1 having an outer diameter matching the inner diameter of the groove 121 is provided and accommodated. As a result, a plurality of (two in FIG. 1) excimer lamps are provided. Further, the inside of the lamp house 10 is filled with an inert gas such as nitrogen gas.
Here, the light irradiation window 11 is formed of a flat plate-shaped window plate member 111 formed of, for example, synthetic quartz glass, and transmits the ultraviolet light emitted from the excimer lamp 1 and irradiates the ultraviolet light downward.
[0016]
As the excimer lamp 1, an excimer lamp such as a xenon lamp utilizing excimer molecular emission by xenon gas is used.
Specifically, as shown in FIG. 2, the excimer lamp 1 has a cylindrical outer tube 2 made of a dielectric material such as synthetic quartz glass, and is arranged inside the outer tube 2 along the tube axis. A cylindrical inner tube 3 having an outer diameter smaller than the inner diameter of the outer tube 2 and made of a dielectric material such as synthetic quartz glass, and both ends of a cylindrical space formed by the outer tube 2 and the inner tube 3; It has a closed discharge vessel 4 having a double tube structure composed of end walls 5 and 6 that hermetically close the portion. The discharge vessel 4 forms a cylindrical discharge space S, and this discharge space is formed. Xenon gas is sealed in S.
[0017]
The outer tube 2 forming the discharge vessel 4 is provided with one net-like electrode 7 made of a conductive material such as a wire mesh in close contact with the outer peripheral surface, and the inner tube 3 has The other electrode 8 made of, for example, an aluminum plate is provided in close contact with the inner peripheral surface. The one electrode 7 and the other electrode 8 are connected to a lighting power supply that supplies high-frequency power to the excimer lamp.
[0018]
To give an example of dimensions of the excimer lamp 1, the overall length of the outer tube 2 forming the discharge vessel 4 is 250 mm, the outer diameter is 26 mm, the wall thickness is 1.0 mm, the total length of the inner tube 3 is 250 mm, the inner diameter is 14 mm, The wall thickness is 1.0 mm, and xenon gas is sealed in the discharge vessel 4 at a pressure of 30 kPa.
[0019]
The lighting power supply device has, for example, a lighting circuit having a configuration shown in FIG.
In FIG. 3, reference numeral 13 denotes a high-frequency power generation circuit that generates high-frequency high-frequency power having a frequency of 1 MHz or more, particularly 1 MHz to 1 GHz, and 14 denotes a modulation that generates a modulation signal at a timing based on a preset control program. Signal generation circuits, 15 and 15, mixers for modulating high-frequency high-frequency power with modulation signals, 16 and 16 amplification circuits, 17 and 17 matching circuits, 1a and 1b excimer lamps.
[0020]
The high-frequency high-frequency power HW generated from the high-frequency power generation circuit 13 has a waveform shown in FIG. 4A, and a modulation signal DS generated from the modulation signal generation circuit 14 and having a pulse-like period described later is: The pulsed high-frequency power PW having the waveform shown in FIG. 4B and obtained by superimposing and modulating the high-frequency high-frequency power HW with the modulation signal DS in the mixer 15 has the waveform shown in FIG. The ultraviolet light LI emitted from the excimer lamp 1a or 1b when the pulsed high-frequency power PW is supplied through the amplifier circuit 16 and the matching circuit 17 has the intensity shown in FIG. 4D.
[0021]
The modulation signal generated by the modulation signal generation circuit 14 has a frequency in the range of 1 kHz to 1/10 of the frequency related to the high-frequency high-frequency power HW, and has a duty ratio of 10 to 80%. If the frequency of the modulation signal is too low, or if the duty ratio is too high, one lighting state is maintained when the high-frequency high-frequency power is intermittently supplied to the excimer lamp, as described later. The time becomes excessively long, and the light emission output due to an increase in the temperature of the excimer gas, a decrease in excimer molecule generation efficiency, and the like is attenuated. Further, when the frequency of the modulation signal is too high or the duty ratio is too small, the lighting time of one lighting state of the excimer lamp becomes excessively short, so that the generation of excimer molecules is sufficiently reduced. High emission intensity cannot be obtained.
[0022]
In the matching circuit 17, circuit constants are set in advance so that the impedance of the lighting circuit matches the impedance of the excimer lamp in the lighting state.
[0023]
In this excimer light source device, the timing at which the supply of high-frequency power to each excimer lamp is started (hereinafter, also simply referred to as “power supply start timing”), that is, the start timing of the pulse cycle in the pulsed high-frequency power PW is Is determined by the timing at which the modulation signal DS generated from the modulation signal generation circuit 14 is turned “on”.
[0024]
Then, in the modulation signal generating circuit 14, the power supply start timing related to the pulsed high-frequency power (hereinafter, also simply referred to as "one pulse power") PWa supplied to the excimer lamp 1a and the excimer lamp 1b. The pulsed high-frequency power (hereinafter, also simply referred to as “the other pulse power”) is controlled so as to have a time lag with the power supply start timing related to the PWb.
[0025]
That is, when the one pulse power PWa and the other pulse power PWb are obtained by modulating the high-frequency high-frequency power with the common modulation signal, the time difference Td related to the power supply start timing is determined by It is set within a period longer than the off-time and shorter than the on-period of the pulsed high-frequency power.
[0026]
Here, the “on period” means a period during which high-frequency power is supplied to the excimer lamp (for example, P1 in FIG. 5), and the “off period” indicates high-frequency power to the excimer lamp. (For example, P2 in FIG. 5).
[0027]
Thereby, the supply of the high-frequency power to one of the excimer lamps is started while the one excimer lamp receives a part of the ultraviolet light radiated from the other excimer lamp, Achieved for both excimer lamps.
[0028]
FIG. 5 is an explanatory waveform diagram showing a timing of a cycle in which high-frequency power is supplied to a plurality of (two in the figure) excimer lamps in the excimer light source device of the present invention.
In this figure, one pulse power PWa and the other pulse power PWb by the modulation signal have a pulse shape in which the ON period P1 is 35 microseconds, the OFF period is 15 microseconds, and one cycle is 50 microseconds. The time difference (time difference from the time point T1 to the time point T2 in FIG. 5) Td between the power supply start timings for each cycle is 20 microseconds.
[0029]
Then, as shown in the figure, at time T1 when one pulse power PWa is turned “on”, the other pulse power PWb is in the “on” state, and the other pulse power PWb is turned “on”. At a certain time point T2, the state where one pulse power PWa is turned “ON” is achieved.
[0030]
With the above configuration, in the above-described excimer light source device, when the supply of the high-frequency power to one of the excimer lamp 1a and the excimer lamp 1b is started, the other is always turned on. As a result, the loss energy due to the reflected wave due to the start of the supply of the high-frequency power to the excimer lamps 1a and 1b is suppressed, and as a result, high luminous efficiency is realized.
[0031]
FIG. 6A is an explanatory drawing showing the generation intensity of a reflected wave with time when the supply of high-frequency high-frequency power to a single excimer lamp is started, and FIG. 6B is a drawing for one excimer lamp. FIG. 5 is an explanatory drawing showing the generation intensity of reflected waves with time when supply of high-frequency high-frequency power is started while the one excimer lamp is receiving ultraviolet rays from another excimer lamp.
[0032]
6A and 6B, during the period Δt1 from the time t1 when the supply of the high-frequency high-frequency power to the excimer lamp is started to the time t3, the state shifts to the complete lighting state in which the discharge is stably maintained. After the time t3, a complete lighting period in which the complete lighting state is achieved and maintained is shown.
In the illustrated example, in the complete lighting state during the complete lighting period, since the impedance of the lighting circuit matches the impedance of the excimer lamp, the generation of reflected waves is extremely small.
[0033]
In the lighting preparation state in which discharge of the excimer lamp occurs, and during the lighting transition period Δt1 for shifting to the complete lighting state, the impedance of the lighting circuit is inconsistent with the impedance of the excimer lamp. Although a large reflected wave is generated, since the excimer lamp exhibits excellent startability by being irradiated with ultraviolet rays, the lighting transition period Δt1 becomes extremely short. The time during which impedance matching is not obtained is shortened, and the total loss energy due to actually generated reflected waves can be sufficiently suppressed. As a result, high luminous efficiency can be obtained for the excimer lamp.
[0034]
Therefore, according to the excimer light source device of the present invention, the supply of high-frequency high-frequency power having a frequency of 1 MHz or more to one excimer lamp is performed while the one excimer lamp receives the ultraviolet radiation radiated from the other excimer lamp. By being started, the length of the lighting transition period during which impedance matching with the lighting circuit is not obtained can be extremely shortened. As a result, even when the supply of high-frequency power is intermittently repeated for one excimer lamp, the reflected wave generated due to the impedance mismatch caused by the supply of high-frequency power to the one excimer lamp is used. Total loss energy can be sufficiently suppressed. In addition, a rise in the temperature of the excimer gas and a decrease in the excimer molecule generation efficiency are suppressed, and a high luminous output can be reliably obtained. Therefore, a high luminous efficiency is obtained as compared with the overall power consumption. be able to.
[0035]
As described above, the present invention has been described based on the specific embodiments. However, the present invention is not limited to the above-described example, and various changes can be made.
For example, the excimer light source device may have a configuration in which three or more excimer lamps are provided. In the excimer light source device having such a configuration, the excimer light source device receives ultraviolet light radiated from at least one excimer lamp. Then, supply of high-frequency power to any other excimer lamp may be started.
[0036]
In the above-described excimer light source device, it is preferable that at least one other excimer lamp that irradiates one of the excimer lamps with ultraviolet light is disposed adjacent to any one of the excimer lamps. As a result, ultraviolet rays are irradiated to any of the excimer lamps with higher efficiency, and in the excimer lamp, more excellent startability can be obtained. The lighting transition period in which no mismatch is obtained becomes extremely short, and as a result, the total energy loss due to the actually generated reflected waves can be sufficiently suppressed, and high luminous efficiency can be obtained for the excimer lamp.
[0037]
Furthermore, in the excimer light source device, all of the high frequency power supply start operations that are repeatedly performed on at least one excimer lamp are performed while receiving ultraviolet light from any other excimer lamp. It is not mandatory.
[0038]
Hereinafter, experimental examples performed to confirm the operation and effect of the present invention will be described.
[0039]
[Experimental example]
According to the configuration of FIG. 1, an excimer lamp having the configuration shown in FIG. 2 and an excimer light source device including a lighting power supply having a lighting circuit having the configuration shown in FIG. 3 were produced.
In this excimer light source device, high-frequency power having a frequency of 2 MHz is modulated by a modulation signal having a frequency of 20 kHz and a duty ratio of 70%, and the on period is 35 microseconds, the off period is 15 microseconds, and the frequency is 50 microseconds. Pulsed high frequency power with a pulsed period was obtained.
This pulse-like high-frequency power is applied to the mode shown in FIG. 5, that is, the time difference between the power supply start time for one excimer lamp (1a) and the power supply start time for the other excimer lamp (1b) is 20 microseconds. , And supplied to each of the two excimer lamps under the condition that the incident power was 300 W.
As a result, the total energy loss due to the reflected wave was 30 W.
[0040]
(Comparative experiment example)
In the above experimental example, pulsed high-frequency power was supplied to each of the two excimer lamps at exactly the same timing.
As a result, the total energy loss due to the reflected wave was 140 W.
[0041]
From the above results, it was confirmed that by supplying high-frequency power to the excimer lamp according to the aspect of the present invention, the total loss energy due to reflected waves can be significantly suppressed.
[0042]
【The invention's effect】
In the excimer lamp, in the state where the ultraviolet light is irradiated, much better starting performance can be obtained than when the ultraviolet light is not irradiated. According to the excimer light source device of the present invention, Supply of high-frequency high-frequency power having a frequency of 1 MHz or more to the excimer lamp is started while the one excimer lamp is receiving ultraviolet rays radiated from another excimer lamp, thereby supplying the high-frequency high-frequency power. Transitions to a fully lit state in a very short time from the start of the operation, the time during which impedance matching with the lighting circuit is not obtained is shortened, and therefore, the reflected wave generated by the impedance mismatch The total energy loss is sufficiently suppressed, and as a result, high luminous efficiency can be obtained in the excimer lamp.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view schematically showing a configuration of an excimer light source device according to an embodiment of the present invention.
FIG. 2 is an explanatory cross-sectional view showing a configuration according to an example of an excimer lamp provided in the excimer light source device of the present invention by a cross section along a tube axis.
FIG. 3 is a block diagram illustrating a schematic configuration of a lighting circuit.
FIG. 4 is an explanatory drawing showing an example of high-frequency power, a modulation signal, a waveform related to modulated high-frequency power, and light emission intensity of an excimer lamp.
FIG. 5 is an explanatory waveform diagram showing a timing of a cycle in which high-frequency power is supplied to a plurality of (two in the figure) excimer lamps in the excimer light source device of the present invention.
FIG. 6A is an explanatory drawing showing the generation intensity of a reflected wave over time when supply of high-frequency high-frequency power to a single excimer lamp is started, and FIG. 6B is a drawing for one excimer lamp; FIG. 7 is an explanatory drawing showing the generation intensity of reflected waves with time when supply of high-frequency high-frequency power is started while the one excimer lamp is receiving ultraviolet rays from another excimer lamp.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 excimer lamp 1 a excimer lamp 1 b excimer lamp 2 outer tube 3 inner tube 4 discharge vessel 5 end wall 6 end wall 7 one electrode 8 the other electrode 10 lamp house 11 light irradiation window 111 window plate member 12 cooling block 121 groove S discharge Space 13 High-frequency power generation circuit 14 Modulation signal generation circuit 15 Mixer 16 Amplification circuit 17 Matching circuit

Claims (2)

A plurality of excimer lamps, and a lighting power supply device for lighting these excimer lamps by intermittently supplying high-frequency power having a frequency of 1 MHz or more,
An excimer light source device, wherein the lighting power supply device starts supplying high frequency power to one excimer lamp while the one excimer lamp receives ultraviolet rays from another excimer lamp. . 2. The excimer light source device according to claim 1, wherein the other excimer lamp is disposed adjacent to the one excimer lamp. .

Images