EXCIMER LASER OSCILLATION DEVICE HAVING GAS RECYCLE FUNCTION

Abstract

It is an object to provide a removal function of removing impurities from exhaust gas including rare gas (for example, argon, xenon, krypton and the like) that is used in an excimer laser oscillation device, in a system of the excimer laser oscillation device.

The excimer laser oscillation device including a gas recycle function includes an oscillation chamber in which laser gas having halogen gas, rare gas and buffer gas is filled inside, a first impurity removing device that removes impurities in exhaust gas that is discharged from the oscillation chamber, inside the system of the excimer laser oscillation device.

Claims

1. An excimer laser oscillation device including a gas recycle function, comprising: an oscillation chamber in which laser gas having halogen gas, rare gas and buffer gas is filled inside; and a first impurity removing device that removes impurities in exhaust gas that is discharged from the oscillation chamber, inside a system of the excimer laser oscillation device.

2. The excimer laser oscillation device according to claim 1, further comprising: a treatment selection section that selects any one of first treatment that discharges exhaust gas to outside air, second treatment that executes impurity removing treatment, and third treatment that feeds the exhaust gas to a process at a subsequent stage, based on a result measured in the impurity concentration measurement section.

3. The excimer laser oscillation device according to claim 1, wherein the first impurity removing device includes an impurity concentration measurement section that measures an impurity concentration in exhaust gas that is discharged from the oscillation chamber.

4. The excimer laser oscillation device according to claim 1, wherein the first impurity removing device includes a decomposing device that decomposes a carbon fluoride that is a part of the impurities to a decomposition byproduct.

5. The excimer laser oscillation device according to claim 2, wherein the first impurity removing device includes a decomposition byproduct removal section that causes the decomposition byproduct generated in the decomposing device to react with a predetermined reaction agent and removes the decomposition byproduct from the exhaust gas.

6. The excimer laser oscillation device according to claim 1, wherein the first impurity removing device has a fluorine compound removal section that removes a fluorine compound that is a part of impurities.

7. The excimer laser oscillation device according to claim 6, further comprising: a treatment selection section that selects any one of first treatment that discharges exhaust gas to outside air, second treatment that executes impurity removing treatment, and third treatment that feeds the exhaust gas to a process at a subsequent stage, based on a result measured in the impurity concentration measurement section.

8. The excimer laser oscillation device according to claim 6, wherein the first impurity removing device includes an impurity concentration measurement section that measures an impurity concentration in exhaust gas that is discharged from the oscillation chamber.

9. The excimer laser oscillation device according to claim 6, wherein the first impurity removing device includes a decomposing device that decomposes a carbon fluoride that is a part of the impurities to a decomposition byproduct.

10. The excimer laser oscillation device according to claim 9, further comprising: a treatment selection section that selects any one of first treatment that discharges exhaust gas to outside air, second treatment that executes impurity removing treatment, and third treatment that feeds the exhaust gas to a process at a subsequent stage, based on a result measured in the impurity concentration measurement section.

11. The excimer laser oscillation device according to claim 9, wherein the first impurity removing device includes an impurity concentration measurement section that measures an impurity concentration in exhaust gas that is discharged from the oscillation chamber.

12. The excimer laser oscillation device according to claim 9, wherein the first impurity removing device includes a decomposition byproduct removal section that causes the decomposition byproduct generated in the decomposing device to react with a predetermined reaction agent and removes the decomposition byproduct from the exhaust gas.

13. The excimer laser oscillation device according to claim 12, further comprising: a treatment selection section that selects any one of first treatment that discharges exhaust gas to outside air, second treatment that executes impurity removing treatment, and third treatment that feeds the exhaust gas to a process at a subsequent stage, based on a result measured in the impurity concentration measurement section.

14. The excimer laser oscillation device according to claim 12, wherein the first impurity removing device includes an impurity concentration measurement section that measures an impurity concentration in exhaust gas that is discharged from the oscillation chamber.

15. The excimer laser oscillation device according to claim 14, further comprising: a treatment selection section that selects any one of first treatment that discharges exhaust gas to outside air, second treatment that executes impurity removing treatment, and third treatment that feeds the exhaust gas to a process at a subsequent stage, based on a result measured in the impurity concentration measurement section.

16. The excimer laser oscillation device according to claim 14, further comprising: a second impurity removing device that further removes impurities from first purified gas that is treated in the first impurity removing device, inside the system of the excimer laser oscillation device.

17. The excimer laser oscillation device according to claim 1, further comprising: a second impurity removing device that further removes impurities from first purified gas that is treated in the first impurity removing device, inside the system of the excimer laser oscillation device.

18. The excimer laser oscillation device according to claim 17, wherein the second impurity removing device further includes: a first removal section that removes a first impurity from the first purified gas, and a second removal section that removes a second impurity from the first purified gas that passes through the first removal section.

19. The excimer laser oscillation device according to claim 18, wherein the second impurity removing device further includes: a xenon removal section that removes the xenon when an argon (Ar) is included as first rare gas, and xenon (Xe) is included as second rare gas in the first purified gas, and an introduction line for introducing auxiliary xenon-containing neon gas to mix the auxiliary xenon-containing neon gas.

20. The excimer laser oscillation device according to claim 17, wherein the second impurity removing device further includes: a xenon removal section that removes the xenon when an argon (Ar) is included as first rare gas, and xenon (Xe) is included as second rare gas in the first purified gas, and an introduction line for introducing auxiliary xenon-containing neon gas to mix the auxiliary xenon-containing neon gas.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0170] FIG. 1A is a diagram illustrating a configuration example of an excimer laser oscillation device of Embodiment 1.

[0171] FIG. 1B is a diagram illustrating a configuration example of the excimer laser oscillation device of Embodiment 1.

[0172] FIG. 2A is a diagram illustrating a configuration example of an excimer laser oscillation device of Embodiment 2.

[0173] FIG. 2B is a diagram illustrating a configuration example of the excimer laser oscillation device of Embodiment 2.

[0174] FIG. 3 is a diagram illustrating a configuration example of an excimer laser oscillation device of Embodiment 3.

[0175] FIG. 4 is a diagram illustrating a configuration example of an excimer laser oscillation device of Embodiment 4.

[0176] FIG. 5 is a diagram illustrating a configuration example of an excimer laser oscillation device of Embodiment 5.

[0177] FIG. 6 is a diagram illustrating a configuration example of an excimer laser oscillation device of Embodiment 6.

DESCRIPTION OF EMBODIMENTS

Embodiment 1

[0178] An excimer laser oscillation device 1 of Embodiment 1 will be described with use of FIGS. 1A and 1B.

[0179] The excimer laser oscillation device is, for example, krypton fluorine (KrF) excimer laser oscillation device, an argon fluorine (ArF) excimer laser oscillation device, an argon/xenon fluorine (Ar/Xe.F) excimer laser oscillation device.

[0180] The excimer laser oscillation device 1 of Embodiment 1 includes an oscillation chamber 12 in which laser gas having halogen gas (for example, fluorine), rare gas (for example, krypton, argon and xenon), and buffer gas (for example, neon, helium and chlorine) is filled inside, a first impurity removing device 13 that removes impurities in exhaust gas that is discharged from the oscillation chamber 12, and a second impurity removing device 14 that removes impurities from the first purified gas that is fed from the first impurity removing device 13, inside a system of the excimer laser oscillation device 1.

[0181] The oscillation chamber 12 is filled with a predetermined amount of laser gas having a predetermined pressure. In this state, a high voltage pulse generator 11 applies high-voltage pulse discharge to at least a pair of electrodes with respect to laser gas (excitation gas) in the oscillation chamber 12, whereby excimer in an excited state is generated, and causes induced emission, and light is obtained. Light emitted from the oscillation chamber 12 is adjusted to a specific wavelength width by a band narrowing module not illustrated. The light which is returned from the band narrowing module to the oscillation chamber 12 is amplified by passing between the above described pair of electrodes. The band narrowing module and an output mirror connect to each other on an optical path line so as to pass through the oscillation chamber 12, and every time light reciprocates between the band narrowing module and the output mirror, light is amplified by passing between the pair of electrodes. The light transmitting through the output mirror is outputted to an exposure device, for example, as output laser light. Here, a function of a resonator is realized by the band narrowing module and the output mirror, but the function of the resonator may be realized by other components.

[0182] Laser gas that is filled in the oscillation chamber 12 has excitation gas including, for example, neon gas or buffer gas such as helium (90 to 95%, for example), rare gas (Kr, Ar, Xe) (5 to 9%, for example), and halogen gas (F.sub.2) (1 to 5%, for example). For example, as excitation gas, KrF, ArF, XeF, Ar/XeF and the like are cited.

[0183] In the present embodiment, it is main component buffer gas (neon, for example) including rare gas of same components as laser gas components (for example, krypton, argon, argon xenon) that is returned to the oscillation chamber 12 as recycle gas. Halogen gas-containing main component buffer gas and recycle gas are mixed, and thereafter, may be fed to the oscillation chamber 12.

[0184] The excimer laser oscillation device 1 may have a first laser gas supply line for feeding first laser gas to the oscillation chamber 12, a second laser gas supply line for feeding second laser gas, and a recycle gas line that feeds recycle gas.

[0185] The first laser gas may be halogen gas-containing main component buffer gas or rare gas and halogen gas-containing main component buffer gas.

[0186] The second laser gas may be halogen gas-containing main component buffer gas or rare gas and halogen gas-containing main component buffer gas.

[0187] In each of the first laser gas supply line, and the second laser gas supply line, a control valve, a gas flow meter, a gas flow rate adjustment section, a pressure gauge, a pressure adjustment section (a pressure reduction valve, for example) and the like are disposed, the first laser gas supply line and the second laser gas supply line are controlled by a control device when laser gas is supplied to the oscillation chamber 12, and laser gas at a predetermined pressure and a predetermined flow rate is supplied to the oscillation chamber.

[0188] In FIG. 1A, the first laser gas is supplied at a predetermined pressure (a first pressure) to the excimer laser oscillation device 1 through a supply line L1 from a supply container 10. In the supply line L1, a supply valve 101, a gate valve 102 (may or may not be present), a gas flow rate adjustment section 104 and a supply gate valve 103 are disposed. The gas flow rate adjustment section 104 has a gas flow meter, and a gas flow rate adjustment valve, and adjusts a valve in accordance with a measurement value of the gas flow meter and controls a gas flow rate. Instead of the gas flow rate adjustment section 104, a gas flow meter, a pressure gauge, and a pressure reduction adjustment section may be disposed.

[0189] The control device of the excimer laser oscillation device 1 controls the supply valve 101 and/or the supply gate valve 103 to close when only recycle gas is supplied to the oscillation chamber 12, for example. First pressure is set in accordance with the specifications of the excimer laser oscillation device 1, and is 300 KPa to 700 KPa, for example.

[0190] Further, the second laser gas supply line (not illustrated) for supplying the second laser gas is provided to be connected to the supply line L1, the oscillation chamber 12 or recycle lines (L31, L6). In the second laser gas supply line (not illustrated), various valves and a gas flow rate adjustment section are disposed as in the first laser gas supply line.

[0191] When a pressure of the first laser gas in the supply container 10 is larger than a first pressure, the pressure of the first laser gas may be reduced to the first pressure by the gas pressure reduction valve (not illustrated) which is disposed at an upstream side or a downstream side of the gas flow rate adjustment section 104.

[0192] When a pressure of the second laser gas in the supply container not illustrated is larger than the first pressure, the pressure of the second laser gas may be reduced to the first pressure by a gas pressure reduction valve (not illustrated).

First Impurity Removing Device

[0193] FIG. 1B illustrates configuration examples of the first impurity removing device 13 and the second impurity removing device 14.

[0194] The exhaust gas which is discharged from the oscillation chamber 12 is fed to the first impurity removing device 13 through the exhaust gas line L2. The exhaust gas is discharged by a second pressure that is from an atmospheric pressure to the above described first pressure inclusive. The second pressure is also set in accordance with the specifications of the excimer laser oscillation device 1. Note that a discharging pump (not illustrated) may be disposed in the exhaust gas line L2 and may be configured to execute (or promote) discharge of exhaust gas.

[0195] The second pressure is 50 to 100 KPa, for example. The exhaust gas which is discharged includes impurities. As the impurities, for example, a nitrogen, an oxygen, a carbon monoxide, a carbon dioxide, water, CF.sub.4, He, CH.sub.4 and the like are cited.

[0196] The control device of the excimer laser oscillation device 1 has a laser gas supply/discharge control section (not illustrated), and the laser gas supply/discharge control section controls the control valve, the gas flow meter, the gas flow rate adjustment section, the gas pressure reduction valve and the like, and discharges laser gas (exhaust gas) from the oscillation chamber 12 in accordance with a predetermined rule (for example, a regular timing based on the operation time), and supplies any one or two kinds or more of the first laser gas, the second laser gas and the recycle gas in amount corresponding to a discharged amount of the laser gas.

[0197] The exhaust gas line L2 is a decomposition removal treatment line in the first impurity removing device 13.

[0198] First, the exhaust gas is fed to a fluorine compound removal section 131, and a fluorine compound that is a part of impurities is removed.

[0199] Next, the exhaust gas is fed to a buffer space 1321 to be stored so that the exhaust gas is in a constant amount. The buffer space 1321 has a function of storing a predetermined amount of exhaust gas, and stably performing impurity measurement by an impurity concentration measurement section 132 described later.

[0200] The impurity concentration in the exhaust gas is measured by an impurity concentration measurement section 132 which is disposed inside the buffer space 1321. Here, a concentration of CH.sub.4, for example, is measured as an impurity. As the impurity concentration measurement section 132, for example, gas chromatography, a heat conduction type concentration sensor, a semiconductor type concentration sensor and the like can be used.

[0201] A release line L20 for releasing the exhaust gas to outside air from the buffer space 1321 is provided. The release line L20 is configured by having, for example, piping, a vent device for discharging to outside air, and an automatic on-off valve 221.

[0202] A bypass line L21 branches from the decomposition removal treatment line L2 downstream of the buffer space 1321. The bypass line L21 is configured by having piping and an automatic on-off valve 241, for example.

[0203] The decomposition removal treatment line L2 is configured by having, for example, piping and the gas flow rate measurement section 212, and an automatic on-off valve 231. As the gas flow rate measurement section 212, a mass flow meter can be used. A replacement timing determination section (not illustrated) may calculate an amount of impurities, based on a measurement value of the gas flow rate measurement section 212 and a measurement value of the impurity concentration measurement section 132, and obtain a replacement timing of a predetermined reaction agent of a decomposition byproduct removal section 135. The obtained replacement timing may be outputted to an input/output interface and may be reported to an operator.

[0204] Further, in the decomposition removal treatment line L2, a buffer container 133 is disposed at a downstream side from the automatic on-off valve 231, and is configured to store a predetermined amount of exhaust gas in the buffer container 133. At a downstream side from the buffer container 133, a decomposing device 134 that decomposes a carbon fluoride (CF.sub.4) which is a part of impurities to a decomposition byproduct is disposed. In the present embodiment, the decomposing device 134 is a device that irradiates the exhaust gas with excimer laser light.

[0205] A decomposition byproduct removal section 135 is disposed at a downstream side from the decomposing device 134. In the present embodiment, the decomposition byproduct is a fluorine compound, for example, and the decomposition byproduct generated in the decomposing device 134 is caused to react with a predetermined reaction agent (for example, a metallic reaction agent or a gas absorbing reaction agent) to be removed from the exhaust gas. The exhaust gas which passes thorough the decomposition byproduct removal section 135 is referred to as first purified gas. The first purified gas is fed to the second impurity removing device 14 by a gas treatment line L3.

[0206] Further, as another embodiment, the gas flow rate measurement section 212 may or may not be present.

[0207] Determination of treatment selection in the present embodiment is as follows.

[0208] The impurity concentration measurement section 132 measures the concentration of CF.sub.4 in the exhaust gas. In this case, when the concentration of CF.sub.4 is a first threshold value (for example, 100 ppm) or more, a treatment selection section (not illustrated) selects first treatment. When the concentration of CF.sub.4 is larger than a second threshold value (for example, 10 ppm) that is smaller than the first threshold value, and is less than the first threshold value, the treatment selection section selects second treatment, and when the concentration of CF.sub.4 is less than the second threshold value, the treatment selection section selects third treatment.

[0209] Further, as another embodiment, the impurity concentration measurement section 132 measures concentrations of CF.sub.4, N.sub.2 and He in the exhaust gas.

[0210] In this case, when

[0211] (a) an He concentration is the third threshold value (for example, 1.0%) or more,

[0212] (b) either CF.sub.4 or N.sub.2 is the first threshold value (100 ppm, for example) or more, or

[0213] (c) the He concentration is less than the third threshold value, either CF.sub.4 or N.sub.2 is from the second threshold value (10 ppm, for example) to the first threshold value, and a large/small relationship of concentration is N.sub.2>()CF.sub.4, the treatment selection section selects the first treatment.

[0214] (d) When the He concentration is less than the third threshold value, and a concentration of N.sub.2 or CF.sub.4 is from the second threshold value to the first threshold value, and the large/small relationship of the concentration is N.sub.2<()CF.sub.4, the treatment selection section selects the second treatment.

[0215] (e) When the He concentration is less than the third threshold value, and the concentration of N.sub.2 or CF.sub.4 is less than the second threshold value, the treatment selection section selects the third treatment.

[0216] Note that a gas absorbing reaction agent also can be used instead, without being limited to the above described metal reaction agent.

[0217] The control device, the treatment selection section, the control section for various valves, and the replacement timing determination section each may be configured by having hardware such as a CPU (or an MPU), a circuit, firmware, a memory storing a software program and the like, and to operate by cooperation with software.

Second Impurity Removing Device

[0218] The second impurity removing device 14 removes the first and second impurities from the first purified gas which is fed by the gas treatment line L3, and obtains the second purified gas. The gas treatment line L3 is configured by having, for example, piping and one or more automatic on-off valves.

[0219] In the gas treatment line L3, a compressor 141, a first removal section 142, a second removal section 143, and a purified gas buffer tank 144 are disposed in this order. The gas which passes through the second removal section 143 is referred to as the second purified gas (also referred to as recycle gas).

[0220] Further, as another embodiment, a heat exchanger, an adjustment section that adjusts a flow rate of the first purified gas, a flow meter that measures the flow rate of the first purified gas, and the pressure adjustment section that adjusts pressure of the first purified gas may be provided at an upstream side from the first removal section 142. The heat exchanger lowers the temperature of the first purified gas to a predetermined temperature. The gas temperature (60 to 80 C., for example) which rises as the pressure is increased by the compressor 141 can be lowered to a predetermined temperature (15 to 35 C., for example), and the gas temperature is lowered to a temperature range suitable for removal action in various removal sections at the subsequent stage, for example.

[0221] Further, as another embodiment, at a downstream side from the second removal section 142 or at a downstream side of the purified gas buffer tank 144, an adjustment section that adjusts a flow rate of the second purified gas, a flow meter that measures the flow rate of the second purified gas, and a pressure adjustment section that adjusts a pressure of the second purified gas may be provided.

[0222] The compressor 141 increases the pressure of the first exhaust gas to a third pressure. The third pressure is a pressure that is higher than the first pressure by about 50 KPa to 150 KPa, for example. A pressure control section (not illustrated) controls the pressure of the first purified gas based on the measurement value of a pressure gauge which is incorporated in the compressor 141, or a pressure gauge which is disposed downstream from the compressor 141.

[0223] The first removal section 142 is a deoxygenating device filled with a manganese oxide reaction agent or a copper oxide reaction agent, which removes oxygen from the first purified gas. As the manganese oxide reaction agent, there are cited a reaction agent such as a manganese monoxide MnO, a reaction agent such as a manganese dioxide MnO.sub.2, and a manganese oxide reaction agent with an adsorbent as a base. As the copper oxide reaction agent, for example, a reaction agent such as a copper oxide CuO, and a copper oxide reaction agent with the adsorbent as a base are cited.

[0224] The purified gas which passes through the first removal section 142 is fed to the second removal section 143 through a pipe L4.

[0225] The second impurity is a component from which an impurity which is contained in a largest amount in the exhaust gas components, and, for example, a nitrogen, a carbon monoxide, a carbon dioxide, water, CF.sub.4, CH.sub.4, He and the like are cited. CF.sub.4 may be removed by the first impurity removing device (partial removal, complete removal), or CF.sub.4 may bypass the first impurity removing device and may be fed to the second impurity removing device.

[0226] The second removal section 143 is a getter that removes impurities (for example, a nitrogen, a carbon monoxide, a carbon dioxide, water, CH.sub.4) other than oxygen, and is filled with a chemical adsorbent.

[0227] The second purified gas which passes through the second removal section 143 is gas (rare gas-containing main component buffer gas) from which an oxygen and impurities other than an oxygen are removed. The second purified gas is fed to the purified gas buffer tank 144 through a pipe L5.

[0228] The second purified gas in the purified gas buffer tank 144 is fed to the oscillation chamber 12 as recycle gas through a recycle line L6. In the recycle line L6, one kind or more of, for example, an automatic on-off valve that opens at a time of supplying recycle gas, an adjustment section that adjusts a flow rate of recycle gas, a flow meter that measures the flow rate of the recycle gas, and a pressure adjustment section that adjusts a pressure of the recycle gas are provided, and one kind or more of them may be configured to be controlled by a laser gas supply/discharge control section, and supply the recycle gas to the oscillation chamber 12.

Embodiment 2

[0229] The excimer laser oscillation device 1 of Embodiment 2 will be described with use of FIGS. 2A and 2B. Explanation of components similar to the components in Embodiment 1 may be omitted or simplified. As illustrated in FIG. 2A, the excimer laser oscillation device 1 of Embodiment 2 is configured such that the excimer laser oscillation device 1 includes the first impurity removing device 13 in a system thereof, and the second impurity removing device 14 is disposed outside the system thereof.

[0230] As illustrated in FIG. 2B, the second impurity removing device 14 (the compressor 141, the first removal section 142, the second removal section 143, the purified gas buffer tank 144) is disposed outside the system of the excimer laser oscillation device 1.

Embodiment 3

[0231] An excimer laser oscillation device of Embodiment 3 will be described with use of FIG. 3. Explanation of components similar to the components in Embodiments 1 and 2 may be omitted or simplified. A point different from A point different from Embodiments 1 and 2 is that in the configuration of the second impurity removing device 14, a xenon removal section 70 and an auxiliary xenon gas supply function are included. The second impurity is more easily removed in the second removal section 143 when xenon in the exhaust gas is removed for the components of the laser gas. That is, the second impurity removing device 14 may be disposed either in the system or outside the system of the excimer laser oscillation device.

[0232] The xenon removal section 70 is disposed at the subsequent stage of the first removal section 142, and xenon is removed here. The xenon removal section 70 is a de-xenon device filled with active carbon. The purified gas which passes through the xenon removal section 70 is fed to the second removal section 143.

[0233] At a downstream side of the purified gas buffer tank 144, a pressure reduction valve 151 and a gas flow rate adjustment section 152 are disposed. The pressure control section (not illustrated) controls the pressure reduction valve 151 and controls the pressure of the second purified gas, based on a measurement value of a pressure gauge disposed at a downstream side of the pipe L5 or a pressure gauge incorporated in the pressure reduction valve 151. The second purified gas of the purified gas buffer tank 144 is gas of a third pressure, and therefore is decompressed to a same pressure (the first pressure) as the laser gas in the oscillation chamber 12.

[0234] The purified gas flow rate adjustment section 152 has a gas flow meter and a gas flow rate adjustment valve, and the purified gas control section (not illustrated) adjusts the gas flow rate adjustment valve in accordance with a measurement value of the gas flow meter, and controls the flow rate of the second purified gas. Thereby, a supply amount of the second purified gas that is fed to the oscillation chamber 12 can be controlled to be constant. The purified gas flow rate adjustment section 152 may be only the gas flow meter. Disposition of the purified gas flow rate adjustment section 152 or the gas flow meter, and the pressure reduction valve 151 may be opposite to each other.

[0235] At a downstream side of the purified gas flow rate adjustment section 152, an auxiliary rare gas introduction line L7 that joins the pipe L5 is provided. In the auxiliary rare gas introduction line L7, an auxiliary container 71 in which buffer gas (for example, neon) and auxiliary rare gas of xenon are filled, a supply valve (not illustrated), an auxiliary rare gas pressure reduction valve (corresponding to an auxiliary rare gas pressure adjustment section) 72, and an auxiliary rare gas flow rate adjustment section 73 are disposed in this order.

[0236] The pressure control section (not illustrated) controls the auxiliary rare gas pressure reduction valve 72 based on a measurement value of a pressure gauge that is disposed at a downstream side of the auxiliary rare gas introduction line L7, and controls a pressure of the auxiliary rare gas. When the pressure of the auxiliary rare gas in the auxiliary container 71 is larger than the first pressure, the pressure of the auxiliary rare gas is reduced to be the first pressure.

[0237] The auxiliary rare gas flow rate adjustment section 73 has a gas flow meter and a gas flow rate adjustment valve, and the purified gas control section (not illustrated) adjusts the gas flow rate adjustment valve in accordance with the measurement value of the gas flow meter, and controls the flow rate of the auxiliary rare gas. The purified gas control section controls the flow rate of the auxiliary rare gas and the flow rate of the second purified gas so as to obtain xenon-containing gas (main component neon) with same loadings as loadings of the laser gas (for example, argon, xenon, neon).

[0238] In the present embodiment, in the pipe L5, a recycle gas tank 145 that stores recycle gas composed of the second purified gas and the auxiliary rare gas is disposed. Automatic on-off valves may be provided at an inlet side and an outlet side of the recycle gas tank 145. The second purified gas and the auxiliary rare gas are mixed in the recycle gas tank 145 and are stable at a constant concentration.

[0239] The recycle gas in the recycle gas tank 145 is fed to the oscillation chamber 12 through the recycle line L6. In the recycle line L6, for example, one kind or more of, for example, an automatic on-off valve that opens at the time of supplying recycle gas, an adjustment section that adjusts the flow rate of recycle gas, a flow meter that measures the flow rate of the recycle gas, and a pressure adjustment section that adjusts the pressure of the recycle gas are provided, one kind or more of them may be configured to be controlled by the laser gas supply/discharge control section, and to supply the recycle gas to the oscillation chamber 12.

Embodiment 4

[0240] An excimer laser oscillation device of Embodiment 4 will be described with use of FIG. 4. Explanation of similar components to the components in Embodiment 3 may be omitted or simplified. A point different from Embodiment 3 is that an auxiliary container 471 filled with buffer gas (for example, neon) and auxiliary rare gas of xenon is housed in a laser gas tank cabinet 400. In the laser gas tank cabinet 400, the first laser gas tank 10 is also housed. Note that the second impurity removing device 14 may be disposed either in the system or outside the system of the excimer laser oscillation device.

Embodiment 5

[0241] The excimer laser oscillation device 1 of Embodiment 5 will be described with use of FIG. 5. Explanation of similar components to the components in Embodiment 1 may be omitted or simplified. A point different from Embodiment 1 is that the first impurity removing device 13 has the fluorine compound removal section 131, the impurity concentration measurement section 132, the buffer space 1321, the gas flow rate measurement section 212 and the automatic on-off valve 231.

[0242] Note that the first impurity removing device 13 may be configured by having only the fluorine compound removal section 131, or may be configured by having only the impurity concentration measurement section 132.

[0243] As a third impurity removing device 13a, the buffer container 133, the decomposing device 134, and the decomposition byproduct removal section 135 may or not may be provided.

[0244] The compressor 141 is disposed in the gas treatment line L3 of the first purified gas, and an automatic on-off valve 252, and a branch line L31 that branches from the gas treatment line L3 between the compressor 141 and the automatic on-off valve 252 and feeds gas to the oscillation chamber 12 are provided downstream of the compressor 141. Note that a buffer tank (not illustrated) may be disposed at an upstream side of the compressor 141, and may be configured to store a predetermined amount of purified gas.

[0245] Based on the result of the impurity concentration measurement section 132, the purified gas which passes thorough the bypass line L21 or the first purified gas which passes through the third impurity removing device 13a is increased in pressure, and can be fed to the oscillation chamber 21. At this time, the automatic on-off valve 252 is closed, and an automatic on-off valve 251 which is disposed in the branch line L31 is opened. A heat exchanger may be disposed in the gas treatment line L3 or the branch line L31, and the temperature of the first purified gas may be reduced to a predetermined temperature.

[0246] A purified gas buffer tank may be disposed in the branch line L31. The purified gas is fed to the oscillation chamber 12 as recycle gas through the branch line L31. In the branch line L31, for example, one kind or more of an automatic on-off valve that opens at a time of supplying gas, an adjustment section that adjusts a gas flow rate, a flow meter that measures the flow rate of gas, and a pressure adjustment section that adjusts a pressure of gas are provided, and one kind or more of them may be configured to be controlled by a laser gas supply/discharge control section, and supply gas to the oscillation chamber 12.

[0247] Further, as another embodiment, another branch line is disposed at an upstream side from the compressor 141 in the gas treatment line L3, the purified gas that passes through a bypass line L21 from the other branch line or the first purified gas that passes through the third impurity removing device 13a can be fed to the oscillation chamber 21. In the other branch line, the purified gas buffer tank may be disposed. In the other branch line, for example, one kind or more of an automatic on-off valve that opens at a time of supplying gas, an adjustment section that adjusts a gas flow rate, a flow meter that measures a flow rate of gas, and a pressure adjustment section that adjusts the pressure of gas are provided, and one or more of them may be configured to be controlled by the laser gas supply/discharge control section, and supply the gas to the oscillation chamber 12.

Embodiment 6

[0248] The excimer laser oscillation device 1 of Embodiment 6 will be described with use of FIG. 6. Explanation of similar components to the components in Embodiment 5 may be omitted or simplified. A point different from Embodiment 5 is that the third impurity removing device 13a is included in the second impurity removing device 14, and is disposed outside the system of the excimer laser oscillation device 1.

Another Embodiment

[0249] In the above described Embodiments 1 to 6, the release line L20 and the bypass line L21 may or may not be present.

[0250] In the above described Embodiments 1 to 6, the first impurity removing device 13 may or may not be present.

[0251] In the above described Embodiments 1 to 6, the second impurity removing device 14 may or may not be present.

[0252] In the above described Embodiments 1 to 6, the bypass line L21 may be configured to feed the exhaust gas to the oscillation chamber 12 instead of being configured to feed the exhaust gas to the process at the subsequent stage. In such a case, the buffer tank may be disposed in the bypass line L21. The purified gas is fed to the oscillation chamber 12 as the recycle gas through the branch line L31. In the bypass line L21, for example, one kind or more of an automatic on-off valve that opens at a time of supplying gas, an adjustment section that adjusts a gas flow rate, a flow meter that measures the flow rate of gas, and a pressure adjustment section that adjusts a pressure of gas, and one or more of them may be configured to be controlled by the laser gas supply/discharge control section, and supply gas to the oscillation chamber 12.

Recycle Gas Generation Method

[0253] A recycle gas generation method that is executed in a system (in a casing) of the above described excimer laser oscillation device,

[0254] wherein a first impurity removing step of removing impurities in exhaust gas discharged from an oscillation chamber is executed in a system of the excimer laser oscillation device.

[0255] The first impurity removing step may have a fluorine compound removing step of removing a fluorine compound that is a part of the impurities.

[0256] The first impurity removing step may have

[0257] a decomposing step of decomposing a carbon fluoride that is a part of impurities to a decomposition byproduct, and

[0258] a decomposition byproduct removing step of causing the decomposition byproduct generated in the decomposing step to react with a predetermined reaction agent and removing the decomposition byproduct from the exhaust gas.

[0259] The first impurity removing step may have an impurity concentration measuring step of measuring an impurity concentration in the exhaust gas which is discharged from the oscillation chamber.

[0260] In the recycle gas generation method,

[0261] a second impurity removing step of further removing impurities from the first purified gas which is treated in the first impurity removing step may be further executed in the system of the excimer laser oscillation device.

[0262] The second impurity removing step may have a pressure increasing step of increasing the pressure of the first purified gas to a predetermined pressure.

[0263] The second impurity removing step may have a first removing step of removing a first impurity from the first purified gas, and

[0264] a second removing step of removing a second impurity from the first purified gas after the first removing step.

[0265] The second impurity removing step may have

[0266] a xenon-containing recycle gas generation step of mixing the second purified gas and auxiliary xenon-containing neon gas after the second removing step, when argon (Ar) as first rare gas and xenon (Xe) as second rare gas are contained in the first purified gas.

[0267] The second impurity removing step may have

[0268] a heat exchange step of lowering a temperature of the first purified gas after the pressure increasing step.

REFERENCE SIGNS LIST

[0269] 1 Excimer laser oscillation device [0270] 11 High-voltage pulse generator [0271] 12 Oscillation chamber [0272] 13 First impurity removing device [0273] 131 Fluorine compound removal section [0274] 132 Impurity concentration measurement section [0275] 133 Buffer container [0276] 134 Decomposing device [0277] 135 Decomposition byproduct removal section [0278] 14 Second impurity removing device [0279] 141 Compressor [0280] 142 First removal section [0281] 143 Second removal section [0282] 144 Purified gas buffer tank