JP6812400B2 - Excimer laser oscillator with gas recycling function - Google Patents

Description

The present invention removes impurities from the exhaust gas discharged from the excimer laser oscillation chamber, and recovers, for example, krypton-containing neon gas, xenon and argon-containing neon gas, and xenon-containing neon gas, which are rare gases required for an excimer laser oscillator. The present invention relates to an excimer laser oscillator that can be reused as recycled gas.

The conventional excimer laser oscillator does not have a function to recycle the laser gas (laser medium gas) used in this oscillator, and the exhaust gas (used) discharged outside the system of the excimer laser oscillator is separate from the oscillator. A recycling system (also called a neon recovery system) that removes impurities from the laser gas) was required. Generally, the mainstream technology is to separate impurities and rare gases in the exhaust gas using various separation technologies such as low temperature separation, purify them as high-purity neon gas with neon content of 99% or more, and recycle them as raw material gas for laser gas. ..

For example, Patent Document 1 is an example of a method for removing a fluorine compound in a step of reusing exhaust gas discharged from an excimer laser oscillator to the outside of the system.
Further, Patent Document 2 describes a method of recovering neon gas from an excimer laser oscillator using a xenon-chlorine gas.
In addition, it is possible to remove trace impurities contained in the exhaust gas of various processes that use krypton and xenon, and it is installed near an excimer laser oscillator to separate and recover only rare gas (krypton, xenon) and reuse it. The recovery device is described in Patent Document 3.
Further, the patent document describes a configuration in which halogen is removed from the laser gas (exhaust gas) discharged from the excimer laser oscillator to the outside of the system, the laser gas component is replenished after a predetermined purification process, and the laser gas component is sent to the excimer laser oscillator again for reuse. It is described in 4.
Further, Patent Document 5 describes that only high-purity neon gas is recovered from the exhaust gas of the main component neon gas containing a large amount of impurities discharged from the KrF excimer laser oscillator to the outside of the system.

Further, Patent Document 6 describes a method using silent discharge as a method for decomposing CF ₄ in exhaust gas, and Non-Patent Document 1 describes a method using corona discharge.

JP-A-2010-92920 Japanese Unexamined Patent Publication No. 2008-168169 Japanese Unexamined Patent Publication No. 2004-161503 Japanese Unexamined Patent Publication No. 11-54851 Japanese Unexamined Patent Publication No. 2001-232134 Japanese Unexamined Patent Publication No. 2006-110461

T. IEEE Japan, Vol. 117-A, No. 10 (1997) "Removal of gaseous impurities in excimer gas by corona discharge"

As disclosed in the above background technology and Patent Documents 1 to 5, in order to recycle the exhaust gas discharged to the outside of the system from the excimer laser oscillator, a separate purification device for recycling is required, and an installation for that purpose is required. Space is needed. Further, since the recycling device and the excimer laser oscillator are separate devices, it is necessary to operate the respective devices in cooperation with each other.

In addition, in order to separate impurities from the exhaust gas discharged from the excimer laser oscillator to the outside of the system, recover high-purity neon gas that is the same as or substantially the same as the neon gas in the raw material laser gas, and recycle it as laser gas. , It is necessary to remove rare gases such as argon (Ar) and krypton (Kr) from the exhaust gas. However, as an exhaust gas purification device that separates these argons and krypton from the exhaust gas, there is a use of cryogenic technology such that the temperature becomes -100 ° C or lower. Further, as a method that does not use the cryogenic technology, a method of increasing the pressure of exhaust gas by a booster or the like and a separation method by an adsorption technology have been proposed. However, cryogenic technology and high pressure and adsorption technology for exhaust gas require a large amount of energy.
In addition, the conventional exhaust gas purification device is large and is designed to handle a large amount of exhaust gas emitted from a plurality of excimer laser oscillators. Then, when the operation of the exhaust gas purification device is stopped, there is a concern that the operation of a plurality of excimer laser oscillators connected to the exhaust gas purification device may be significantly affected.

Further, even if argon (Ar) and krypton (Kr) can be removed and a recycled gas containing neon (Ne) as a main component can be purified, impurities such as CF ₄ generated in the excimer laser oscillator are lasers. Affects oscillation. Although these impurities such as CF ₄ are described in the above patent documents, they are not easy to remove. In addition, it is not easy to detect the concentration of impurities in the exhaust gas (low-purity neon gas) introduced into the exhaust gas purification device. Therefore, when the concentration of impurities in the exhaust gas is high, the performance of the exhaust gas purification device (particularly, a device such as an adsorption removing means) deteriorates faster. Therefore, the frequency of maintenance such as replacement of the adsorption removing means increases.

Further, the impurity removal device of Patent Document 1, has a step of removing impurities containing CF ₄ with an adsorbent such as zeolite, in the case of exhaust gas containing CF ₄ at a high concentration, the CF ₄ in the adsorbent There is a problem that it cannot be completely removed. Therefore, when the CF ₄ generated by the excimer laser oscillator is repeated in the exhaust gas purification process, the CF ₄ concentration in the recycled gas gradually increases, and the laser pulse output energy of the excimer laser oscillator decreases. There is concern about problems. Moreover, the decomposition method has the problem of generating oxygen which is new impurity at CF ₄ decomposition.

Further, the method of decomposing CF _{4 in} the exhaust gas of Patent Document 6 by silent discharge can decompose CF ₄ having a relatively high concentration, but there is a problem that a certain amount of CF ₄ remains even after decomposition. The method of decomposing CF _{4 in} the exhaust gas of Non-Patent Document 1 by corona discharge has a problem that the electrodes are fluorinated and easily deteriorated.

A first object of the present invention is to provide a removal function for removing impurities from exhaust gas containing a rare gas (for example, argon, xenon, krypton, etc.) used in an excimer laser oscillator in the system of the excimer laser oscillator. That is.
A second object of the present invention is to remove some impurities from the exhaust gas discharged from the excimer laser oscillation chamber in the system of the excimer laser oscillator, and to remove other impurities outside the system of the excimer laser oscillator. To remove.
A third object of the present invention is to measure the concentration of impurities in the exhaust gas discharged from the excimer laser oscillation chamber in the system of the excimer laser oscillator, and in the system of the excimer laser oscillator and / or the excimer laser. It is to remove impurities outside the system of the oscillating device.
Another object of the present invention is to recycle a purified gas (laser gas containing a rare gas) from which impurities have been removed.

The excimer laser oscillator having the gas recycling function of the present invention
An oscillation chamber filled with a laser gas having a halogen gas (for example, fluorine), a rare gas (for example, krypton, argon, xenon), and a buffer gas (for example, neon, chlorine).
A first impurity removing device for removing impurities in the exhaust gas discharged from the oscillation chamber is provided in the system of the excimer laser oscillation device.

The first impurity removing device may have a fluorine compound removing portion for removing a fluorine compound which is a part of impurities. The first impurity removing device may have only a fluorine compound removing part.

The first impurity removing device may have a decomposition device that decomposes fluorocarbon (CF _4, etc.) which is a part of impurities into a decomposition by-product.
The first impurity removing device may have a decomposition by-product removing unit that reacts the decomposition by-product produced by the decomposition device with a predetermined reactant and removes it from the exhaust gas. The decomposition by-product when fluorocarbon is decomposed is, for example, a fluorine compound.
The first impurity removing device may not have a fluorine compound removing part, but may have a decomposition device and a decomposition by-product removing part.

The first impurity removing device may have an impurity concentration detecting unit for measuring the impurity concentration in the exhaust gas discharged from the oscillation chamber. The first impurity removing device may not have a fluorine compound removing unit, a decomposition device, and a decomposition by-product removing unit, but may have an impurity concentration detecting unit.
The impurity concentration detecting unit may be set upstream or downstream of the fluorine compound removing unit.
The impurity concentration detection unit may be installed upstream from the decomposition device and used for determining whether or not to remove impurities by the decomposition device. Further, the impurity concentration detection unit may be installed downstream from the decomposition device and measure the concentration of impurities after being processed by the decomposition device.
The impurity concentration detecting unit may measure the concentration of any one or more of CF ₄ , N ₂ , and He as impurities in the exhaust gas.

The first impurity removing device may have a buffer tank for storing exhaust gas upstream and / or downstream of the decomposition device.
The first impurity removing device may have a buffer tank for storing exhaust gas upstream and / or downstream of the decomposition by-product removing unit.
The first impurity removing device may have a buffer tank for storing exhaust gas upstream and / or downstream from the impurity concentration detecting unit.
The first impurity removing device may have a buffer tank for storing exhaust gas upstream and / or downstream of the fluorine compound removing portion.

In the above invention, "inside the system" is a component (including an element protruding from the housing) connected to the housing and the housing if the excimer laser oscillator is a single housing, and excimer laser oscillation. When the device is composed of a plurality of housings, the configuration includes a configuration in which the housings are in contact with each other or arranged in the vicinity thereof.

In the present invention, unless otherwise specified, "upstream" and "downstream" mean the arrangement relationship in the flow direction of gas (exhaust gas, refined gas, recycled gas, raw material laser gas, etc.). The same applies hereinafter.

The appearance (single housing) size of the excimer laser oscillator may be, for example, 2200 to 3500 (W) × 500 to 1500 (D) × 1500 to 2500 (H).
An excimer laser oscillator is a type of gas laser that oscillates light in the ultraviolet region. In the oscillation chamber, by applying a high voltage (high voltage pulse discharge) to the excitation gas with at least a pair of electrodes, an excimer in an excited state is generated, stimulated emission is caused, and light (ultraviolet rays) is obtained.
The light emitted from the oscillation chamber may be adjusted to a specific wavelength width by, for example, a sandwiching module (consisting of a prism and a grating). The light returned from the sandwiched band module to the oscillation chamber is amplified by passing between the pair of electrodes. In addition, the sandwiched band module and the output mirror are connected by an optical path line so as to pass through the oscillation chamber, and each time the light reciprocates between the sandwiched band module and the output mirror, the light passes between the pair of electrodes. , Light is amplified. The function of the resonator is realized by the sandwiched band module and the output mirror. The light transmitted through the output mirror is output as output laser light to, for example, an exposure apparatus.
The laser gas filled in the oscillation chamber is, for example, a buffer gas such as neon gas (for example, 90 to 95%), a rare gas (Kr, Ar, Xe) (for example, 5 to 9%), and a halogen gas (F ₂ ). It has an excitation gas consisting of (eg 1-5%). For example, as the excitation gas, there are KrF, ArF, XeF, Ar / XeF and the like.

The excimer laser oscillator is
One or more laser gas supply lines that supply one or more laser gases to the oscillation chamber, and
The oscillation chamber to which the laser gas is supplied from the laser gas supply line and
It may have an exhaust gas line for sending the laser gas (exhaust gas) discharged from the oscillation chamber to the first impurity removing device (or the impurity concentration detecting unit).
The exhaust gas line and the laser gas supply line may be provided with a control valve, a gas pressure regulator or a gas pressure gauge, and / or a gas flow rate regulator or a gas flow meter.
The excimer laser oscillator may have a pump for discharge.
The excimer laser oscillator may have a laser gas pressure gauge that measures the pressure of the laser gas in the oscillation chamber.
The excimer laser oscillator has a control valve, a gas pressure regulator or a gas pressure gauge, and / or in order to supply a predetermined pressure and a predetermined amount of laser gas to the oscillation chamber and discharge a predetermined amount of laser gas from the oscillation chamber. A gas flow rate adjusting unit meter or a gas flow meter may be installed and controlled by a laser gas supply / emission control unit.
The gas pressure in the oscillation chamber and the supply pressure of the laser gas (first pressure) are set according to the specifications of the excimer laser oscillator, but are usually higher than the atmospheric pressure, for example, 300 KPa or more at the gauge pressure. The range of ~ 700 KPa, preferably 400 KPa or more to 700 KPa, and more preferably 500 KPa or more to 700 KPa is exemplified.
The pressure of the exhaust gas discharged from the oscillation chamber is equal to or higher than the atmospheric pressure and lower than the first pressure. For example, the gauge pressure may be in the range of 50 KPa to 200 KPa.
The pressure of the first purified gas boosted to a predetermined pressure by the booster is a value larger than the first pressure, and for example, the difference from the first pressure is in the range of 50 KPa to 150 KPa in gauge pressure.

The excimer laser oscillator may have a decomposition removal processing line for sending the exhaust gas to the decomposition device and the decomposition by-product removing unit based on the result measured by the impurity concentration detecting unit. .. The decomposition removal processing line may be connected to an exhaust gas line connected to the oscillation chamber, and may also serve as an exhaust gas line.
The excimer laser oscillator may have an emission line for discharging the exhaust gas to the outside of the system of the excimer laser oscillator based on the result measured by the impurity concentration detection unit.
The excimer laser oscillator has a bypass line for sending the exhaust gas to the subsequent process without sending it to the decomposition device and the decomposition by-product removing unit based on the result measured by the impurity concentration detection unit. You may be doing it.

The excimer laser oscillator has a first process of discharging exhaust gas to the outside air, a second process of executing an impurity removal process, and an exhaust gas in a subsequent process based on the results measured by the impurity concentration detection unit. It may have a process selection unit for selecting one of the third process to be sent.
When the first treatment is selected by the treatment selection unit, the exhaust gas is discharged to the outside air at the discharge line.
When the second treatment is selected in the treatment selection unit, the exhaust gas is sent to the decomposition apparatus and the decomposition by-product removing unit provided in the decomposition removal processing line to decompose and remove impurities in the exhaust gas. ,
When the third treatment is selected by the treatment selection unit, the exhaust gas may be sent to a subsequent process at the bypass line.
When the first treatment is selected, the exhaust gas is discharged to the discharge line, and when the second treatment is selected, the exhaust gas is sent to the decomposition / removal treatment line, and the third treatment is selected. It may have a valve control unit that controls the opening and closing of the valve so as to send the exhaust gas to the bypass line.

The decomposition device may be, for example, a silent discharge device or a short wavelength light oscillator. Examples of the short wavelength light include excimer laser light and UV laser light. The disassembly device may have a disassembly chamber. Exhaust gas may be sent from the oscillation chamber to the decomposition chamber and irradiated with excimer laser light in the decomposition chamber to decompose impurities (CF ₄ ) in the exhaust gas. CF ₄ is decomposed into decomposition by-products (F ₂ , other fluorine compounds), and the decomposition by-products may be absorbed and removed by reacting with a predetermined reactant at the decomposition by-product removing section. ..

In the present invention, the above-mentioned "predetermined reactant" is, for example, a metal-based reactant or a gas-absorbing reactant. Examples of the metal-based reactant include Ag-based and Cu-based reactants. Examples of the gas absorption system reactant include an acid gas absorption reactor, and examples thereof include the use of an oxygen-containing substance typified by soda lime as the reactant.

The fluorine compound is, for example, SiF ₄ or COF ₂ .
The fluorocarbon is, for example, CF ₄ .
The disassembly / removal processing line may be configured to include, for example, a pipe and an automatic on-off valve.
The bypass line may be configured to include, for example, piping and an automatic on-off valve.
The discharge line may be configured to include, for example, piping, a vent device for discharging outside air, an automatic on-off valve, and the like.
The impurity concentration detection unit may be arranged in a pipe such as a decomposition removal processing line, may be arranged in a space where concentration measurement can be performed, or may be arranged in a buffer tank.
In the present invention, the "refined gas" and the "recycled gas" are, for example, main component neon gas containing the first rare gas (for example, Ar, Kr).
In the present invention, the impurities in the exhaust gas include, for example, one or more of CF ₄ , N ₂ , He, oxygen, and water. Buffer gases such as rare gases (eg argon, krypton, xenon) and neon are not impurities unless explicitly stated to be impurities.

In the present invention, when the impurity concentration detection unit is provided, the concentration of impurities (for example, CF ₄ ) in the exhaust gas sent from the oscillation chamber can be measured, and various treatments can be performed on the exhaust gas according to the measurement result. ..
In the present invention, for example, when the impurity concentration is higher than the predetermined concentration range (for example, 10 ppm to 120 ppm), the impurities are released to the outside air, and when the impurity concentration is in the predetermined concentration range (for example, 10 ppm to 120 ppm), the impurities are released. It can be decomposed and removed, and if the impurity concentration is less than a predetermined concentration range (for example, 10 ppm to 120 ppm), the exhaust gas can be directly sent to the subsequent process (process of the second impurity removing device).
That is, since only the exhaust gas containing impurities (also referred to as "first purified gas") containing impurities not removed by the first impurity removing device can be sent to the subsequent process (process of the second impurity removing device). Impurities can be further removed in the subsequent process.
Further, it is possible to suppress the phenomenon that the performance of the decomposition by-product removing section of the first impurity removing device or the first and second removing sections of the second impurity removing device deteriorates at an early stage, and to reduce the number of maintenances.
Then, in the system of the excimer laser oscillator, exhaust gas recycling treatment (depending on the embodiment, partial impurity removal treatment, total impurity removal treatment) can be performed. For example, in the system of an ArF excimer laser oscillator or a KrF excimer laser oscillator, impurities can be removed from the exhaust gas to purify the main component neon gas containing the first rare gas and reuse it as a recycled gas.
Further, in the present invention, since the configuration does not remove the rare gas (Ar, Kr), the ultra-low temperature treatment and the high pressure treatment of 1 MPaG or more are not required, and a compact device configuration can be obtained in the system of the excimer laser oscillator. It can be incorporated into the (housing).
In addition, since impurities such as CF ₄ generated in the oscillation chamber can be efficiently removed, the laser oscillation performance can be stabilized.
In addition, by incorporating the gas recycling function into the excimer laser oscillator, gas recycling processing can be performed for each excimer laser oscillator, compared to a large-scale exhaust gas purification device connected to multiple excimer laser oscillators. Recycling efficiency can be improved.
Further, by incorporating the gas recycling function into the excimer laser oscillator, the installation space including the conventional exhaust gas purification device can be saved.
By incorporating the gas recycling function into the excimer laser oscillator, the operation sequence becomes simpler than that of the exhaust gas purification apparatus connected to a plurality of excimer laser oscillators, and a reduction in the failure rate can be expected.

In the above invention, when the impurity concentration detecting unit measures the concentration of CF _{4 in} the exhaust gas,
When the concentration of CF ₄ is equal to or higher than the first threshold value, the processing selection unit selects the first processing.
When the concentration of CF ₄ is larger than the second threshold value smaller than the first threshold value and less than the first threshold value, the process selection unit selects the second process.
When the concentration of CF ₄ is less than the second threshold value, the process selection unit may control to select the third process.
In the above invention, the "first threshold" is, for example, an arbitrary value between 80 ppm and 110 ppm, preferably an arbitrary value between 90 ppm and 100 ppm, and more preferably 100 ppm.
In the above invention, the "second threshold" is, for example, an arbitrary value between 5 ppm and 15 ppm, preferably an arbitrary value between 8 ppm and 12 ppm, and more preferably 10 ppm.
In the present invention, concentration means volume concentration, unless otherwise specified by mass or weight.

The main component of the exhaust gas is neon, and the first rare gas is 1 to 10%, preferably 1 to 8%, based on the total amount. Examples of impurities in the exhaust gas include CF ₄ , N ₂ , He and the like. CF ₄ concentration in the exhaust gas in the range of 1ppm~500ppm is assumed.

When the CF ₄ concentration is equal to or higher than the first threshold value (for example, 100 ppm), the process selection unit selects the first process. In the first treatment, the exhaust gas is discharged to the outside of the system by the discharge line.
When a certain amount (for example, 100 ppm) or more of CF ₄ is introduced into the decomposition apparatus, a part of CF ₄ contained in the exhaust gas is not decomposed and cannot be completely removed. However, with such a configuration, CF ₄ Complete removal can be performed by removing exhaust gas that may be insufficiently removed from the system in advance.
Further, in the case of a high concentration of CF ₄ , the amount of decomposition by-products generated by the decomposition apparatus increases, and the frequency of replacement of predetermined reactants (for example, metal-based reactants and gas-absorbing reactants) increases. Since there is a problem that corrosion of pipes, valves, etc. progresses, these problems are reduced by preventing CF ₄ having a concentration equal to or higher than the first threshold value from being introduced into the decomposition apparatus. The value of the first threshold value may be set according to the capacity of the decomposition device.
When the CF ₄ concentration is larger than the second threshold value (for example, 10 ppm) smaller than the first threshold value and less than the first threshold value, the second process is selected. In the second treatment, the exhaust gas is introduced into the decomposition apparatus from the decomposition removal treatment line. In the decomposition apparatus, CF ₄ becomes a decomposition by-product (F ₂ , other fluorine compounds) by, for example, UV laser light, excimer laser light, or plasma decomposition, and the decomposition by-product is a predetermined reactant (for example, a metal-based reaction). Agent, gas absorption system reactant) is removed by reaction.
When the CF ₄ concentration is less than the second threshold value, the third treatment is selected, the third treatment bypasses the decomposition apparatus, and the exhaust gas is directly introduced into the second impurity removing apparatus in the subsequent stage.

When the impurity concentration detector measures the concentrations of CF ₄ , N ₂ and He in the exhaust gas,
(A) He concentration is equal to or higher than the third threshold value.
(B) Either CF ₄ or N ₂ is greater than or equal to the first threshold (eg, any value between 80 ppm and 110 ppm, preferably 90 ppm to 100 ppm) or
(C) The He concentration is less than the third threshold value, and either CF ₄ or N ₂ is equal to or higher than the second threshold value (for example, any numerical value between 5 ppm and 15 ppm, preferably 8 ppm to 12 ppm) or more. When the value is less than the threshold value and the concentration relationship is N ₂ > (1/2) × CF ₄ , the process selection unit selects the first process.
(D) When the He concentration is less than the third threshold value, the concentration of N ₂ or CF ₄ is equal to or more than the second threshold value and less than the first threshold value, and the magnitude relationship of the concentration is N ₂ <(1/2) ×. In the case of CF ₄ , the process selection unit selects the second process.
(E) Even if the processing selection unit controls to select the third processing when the He concentration is less than the third threshold value and the concentration of N ₂ or CF ₄ is less than the second threshold value. Good.
In the above invention, the "third threshold" is, for example, an arbitrary value between 0.5% and 1.5%, preferably an arbitrary value between 0.8% and 1.2%, more preferably. It is 1.0%.

The concentrations of CF ₄ , N ₂ and He can also be measured as impurities in the exhaust gas. The CF ₄ and N ₂ concentrations in the exhaust gas are assumed to be in the range of ₁ ppm to 500 ppm, and the He concentration is assumed to be in the range of 0.01 to 5.0%.
When the CF ₄ or N ₂ concentration is, for example, 100 ppm or more, or when the He concentration is, for example, 1% or more, the laser intensity is lowered, so that the CF ₄ or N ₂ concentration is the first threshold value (for example, 100 ppm) or more. In the case of, or when the He concentration is equal to or higher than the third threshold value (for example, 1%), the treatment selection unit selects the first treatment, and the first treatment discharges the exhaust gas to the outside of the system by the discharge line.
Even when the He concentration is less than the third threshold value and the CF ₄ and N ₂ concentrations are larger than the second threshold value (for example, 10 ppm) smaller than the first threshold value and less than the first threshold value, the N ₂ concentration is also obtained. There when the CF ₄ concentration twice or more, the amount of ions generated in the decomposition process of the decomposition device is nitrogen ions amount is advantageous for the carbon ion amount. In this case, the nitrogen ions decomposed and generated by the decomposition apparatus react preferentially with oxygen or oxygen ions contained in the exhaust gas rather than carbon ions to generate nitrogen oxides. Therefore, when the N ₂ concentration is twice or more the CF ₄ concentration, the treatment selection unit selects the first treatment, and the first treatment discharges the exhaust gas to the outside of the system by the discharge line.
On the other hand, if the He concentration is less than the third threshold value, the CF ₄ and N ₂ concentrations are equal to or more than the second threshold value and less than the first threshold value, and the N ₂ concentration is less than twice the CF ₄ concentration, the decomposition apparatus is used. Since decomposition is possible and the amount of nitrogen oxides generated by this decomposition is small, the second treatment is selected. In the second treatment, the exhaust gas is introduced into the decomposition device through the decomposition removal treatment line.
When the He concentration is less than the third threshold value and the CF ₄ and N ₂ concentrations are less than the second threshold value, the third process is selected. In the third treatment, the decomposition device is bypassed and the exhaust gas is directly introduced into the second impurity removing device in the subsequent stage.

In the above invention, the fluorine compound removing unit, the impurity concentration detecting unit, the buffer tank, the decomposition apparatus, and the decomposition by-product removing unit may be arranged in this order on the decomposition removal processing line.
In the above invention, the first recycling line may be provided in which the first purified gas processed by the first impurity removing device is returned to the oscillation chamber as a recycling gas.

In the above invention, a gas treatment line may be provided for sending the first purified gas treated by the first impurity removing device to a subsequent process for further treatment.
In the above invention, the excimer laser oscillator may further include a second impurity remover in the system of the excimer laser oscillator that further removes impurities from the first purified gas processed by the first impurity remover. Good.
In the above invention, a second recycling line may be further provided which returns the second purified gas processed by the second impurity removing device as a recycling gas to the oscillation chamber. As another embodiment, the second impurity removing device may be arranged outside the system of the excimer laser oscillator. Alternatively, a second impurity removing device may be arranged inside the system, and a third impurity removing device having a recycling function may be further provided outside the system.

In the above invention, the excimer laser oscillator, the first impurity removing device and / or the second impurity removing device
A booster (for example, a compressor) that boosts the first refined gas to a predetermined pressure (a pressure equal to or higher than the supply pressure of the raw material gas, or a pressure equal to or higher than the pressure in the oscillation buffer). You may have it.
It may have a recycling line for sending the first purified gas having a predetermined pressure by the booster to the oscillation chamber.

In the above invention, the second impurity removing device is
A first removal unit (eg, deoxygenation reaction means) that removes first impurities (eg, oxygen) from the first purified gas,
It may have a second removing part (for example, a getter) that removes second impurities from the first purified gas that has passed through the first removing part.
As another embodiment, instead of the first impurity removing device, a second impurity removing device (which may also include components described later) may be arranged in the system of the excimer laser oscillator.

The booster, the first removing unit, and the second removing unit may be arranged in the common gas treatment line.
The first removing unit may remove the first impurities from the first purified gas whose pressure has been increased to a predetermined pressure by the booster.
The second purified gas (recycled gas) that has passed through the second removing portion may be sent to the oscillation chamber through the second recycling line.

The second impurity removing device is
A gas flow rate adjusting unit for adjusting the flow rate of exhaust gas or a gas flow meter for measuring the flow rate of purified gas may be arranged in the gas treatment line on the downstream side of the booster and upstream of the first removal unit.
The second impurity removing device is
A gas pressure adjusting unit for adjusting the pressure of exhaust gas or a gas pressure gauge for measuring the gas pressure may be arranged in the gas treatment line on the downstream side of the booster and upstream of the first removing unit.

The second impurity removing device is
It may further have a refined gas buffer tank for storing the second refined gas (for example, the main component neon gas containing the first rare gas) that has passed through the second removing portion.

When the laser gas as a raw material is Ar / Xe-containing neon gas, the second impurity removing device contains argon (Ar) as the first rare gas and xenon (Xe) as the second rare gas in the first purified gas. Including
An xenon removing portion for removing xenon from the first purified gas may be further provided between the first removing portion and the second removing portion. Examples of the xenon removing portion include a configuration in which activated carbon or a zeolite-based adsorbent is filled.
When the laser gas as a raw material is Ar / Xe-containing neon gas, the second impurity removing device contains argon (Ar) as the first rare gas and xenon (Xe) as the second rare gas in the first purified gas. Including
An introduction line for introducing auxiliary xenon-containing neon gas may be further provided in the refined gas buffer tank or in the piping of the gas treatment line through which the second refined gas flows. The introduction line may be connected to the refined gas buffer tank or a gas treatment line upstream or downstream thereof. The second refined gas and the xenon-containing neon gas may be mixed in the refined gas buffer tank or the piping of the gas treatment line. The auxiliary xenon-containing neon gas is stored in an auxiliary tank inside or outside the system, and the auxiliary tank may be connected to the introduction line.
A gas flow rate adjusting unit or a gas flow meter, or a gas pressure adjusting unit or a gas pressure gauge may be arranged in the introduction line. The pressure adjusting unit may adjust the pressure of the auxiliary xenon-containing neon gas to a predetermined pressure (for example, the first pressure). The "first pressure" is, for example, the pressure of the laser gas supplied to the oscillation chamber or higher.
The second impurity removing device may further include the second purified gas and a recycling tank for storing the xenon-containing neon gas. The introduction line may be connected to the recycling tank. The second refined gas and the auxiliary xenon-containing neon gas may be mixed in the recycler tank.

The second impurity removing device is
A gas flow rate adjusting unit for adjusting the flow rate of the second purified gas or a gas flow meter for measuring the flow rate of the second purified gas may be arranged in the gas treatment line on the downstream side of the second removing unit. A gas flow rate adjusting unit or a gas flow meter may be arranged on the downstream side of the refined gas buffer tank or the downstream side of the recycling tank.

The second impurity removing device is
A gas pressure adjusting unit for adjusting the pressure of the second purified gas or a gas pressure gauge for measuring the gas pressure may be arranged in the gas processing line on the downstream side of the second removing unit. A gas pressure regulator or a gas pressure gauge may be arranged on the downstream side of the refined gas buffer tank or the downstream side of the recycling tank.

The second impurity removing device is
In the gas treatment line on the downstream side of the second removal unit, a gas pressure adjusting unit for adjusting the pressure of the second purified gas or a gas pressure gauge for measuring the gas pressure, and a gas flow rate for adjusting the flow rate of the second purified gas. The adjusting unit or the gas flow meter for measuring the flow rate of the second purified gas may be arranged in this order. A gas flow control unit for adjusting the flow rate of the second refined gas or a gas flow meter for measuring the flow rate of the second refined gas, and a pressure of the second refined gas are applied to the gas treatment line downstream from the second removal unit. The gas pressure adjusting unit to be adjusted or the gas pressure gauge for measuring the gas pressure may be arranged in this order.

The second impurity removing device may have a configuration in which two xenon removing portions are arranged in parallel, one of which is adsorbed and the other of which is regenerated.

The second impurity removing device may further have a temperature adjusting unit for adjusting the temperature of the first purified gas. Examples of the temperature control unit include a heat exchanger. The temperature adjusting unit is arranged on the downstream side of the booster, preferably between the booster and a predetermined flow rate adjusting unit or gas flow meter, or a gas pressure adjusting unit or gas pressure gauge located on the downstream side of the booster. You may.

According to this configuration, the temperature of the first purified gas can be adjusted to a predetermined temperature. For example, the temperature of the first purified gas (for example, 60 to 80 ° C.) that is boosted and raised by the booster can be adjusted to a predetermined temperature (for example, 15 to 35 ° C.). Further, the temperature of the first purified gas can be adjusted within a temperature range suitable for the removing action in the first and second removing portions in the subsequent stage.

It may have a first bypass line for the first removal section.
It may have a second bypass line for the second removal section.
It may have a third bypass line for the xenon removal section.
A sluice valve is arranged in each of the first to third bypass lines. The sluice valve is opened during bypass processing.
The first removing portion may have a sluice valve at least on the upstream side thereof.
The second removing portion may have a sluice valve at least on the upstream side thereof.
The xenon removing portion may have a sluice valve at least on the upstream side thereof.

(Method)
A recycled gas purification method executed in the system (inside the housing) of the excimer laser oscillator of the present invention.
This is a recycled gas purification method, characterized in that the first impurity removing step of removing impurities in the exhaust gas discharged from the oscillation chamber is executed in the system of the excimer laser oscillator.
The first impurity removing step may include a fluorine compound removing step of removing a fluorine compound which is a part of impurities.
The first impurity removal step is
A decomposition process that decomposes fluorocarbon, which is a part of impurities, into decomposition by-products,
It may have a decomposition by-product removing step unit which reacts the decomposition by-product produced in the decomposition step with a predetermined reactant and removes it from the exhaust gas.
The first impurity removing step may include an impurity concentration measuring step for measuring the impurity concentration in the exhaust gas discharged from the oscillation chamber.

Recycled gas refining method
The second impurity removing step of further removing impurities from the first purified gas treated in the first impurity removing step may be further executed in the system of the excimer laser oscillator.
The second impurity removing step may include a step of stepping up the first purified gas to a predetermined pressure.
The second impurity removing step includes a first removing step of removing the first impurity from the first purified gas.
After the first removing step, a second removing step of removing the second impurities from the first purified gas may be provided.
The second impurity removing step is
When argon (Ar) is contained as the first rare gas and xenon (Xe) is contained as the second rare gas in the first purified gas.
After the second removal step, a xenon-containing recycled gas mixing step of mixing the second purified gas and the auxiliary xenon-containing neon gas may be provided.
The second impurity removing step is
After the pressurizing step, a heat exchange step of lowering the temperature of the first purified gas may be provided.

It is a figure which shows the structural example of the excimer laser oscillator of Embodiment 1. It is a figure which shows the structural example of the excimer laser oscillator of Embodiment 1. It is a figure which shows the structural example of the excimer laser oscillator of Embodiment 2. It is a figure which shows the structural example of the excimer laser oscillator of Embodiment 2. It is a figure which shows the structural example of the excimer laser oscillator of Embodiment 3. It is a figure which shows the structural example of the excimer laser oscillator of Embodiment 4. It is a figure which shows the structural example of the excimer laser oscillator of Embodiment 5. It is a figure which shows the structural example of the excimer laser oscillator of Embodiment 6.

(Embodiment 1)
The excimer laser oscillator 1 of the first embodiment will be described with reference to FIGS. 1A, 1B, and 1C.
The excimer laser oscillator is, for example, a krypton / fluorine (KrF) excimer laser oscillator, an argon / fluorine (ArF) excimer laser oscillator, and an argon xenon fluorine (Ar / Xe / F) excimer laser oscillator.

The excimer laser oscillator 1 of the first embodiment is internally filled with a laser gas having a halogen gas (for example, fluorine), a rare gas (for example, krypton, argon, xenone), and a buffer gas (for example, neon, helium, chlorine). The oscillating chamber 12, the first impurity removing device 13 for removing impurities in the exhaust gas discharged from the oscillating chamber 12, and the first purifying gas sent from the first impurity removing device 13 are the first to remove impurities. (Ii) An impurity removing device 14 is provided in the system of the excimer laser oscillating device 1.

The oscillation chamber 12 is filled with a predetermined pressure and a predetermined amount of laser gas. In this state, the high-voltage pulse generator 11 applies a high-voltage pulse discharge to the laser gas (excited gas) in the oscillation chamber 12 to at least a pair of electrodes to generate an excimer in the excited state and induce it. Light is obtained by causing emission. The light emitted from the oscillation chamber 12 is adjusted to a specific wavelength width by an interbanding module (not shown). The light returned from the sandwiched band module to the oscillation chamber 12 is amplified by passing between the pair of electrodes. The sandwiched band module and the output mirror are connected by an optical path line so as to pass through the oscillation chamber 12, and each time the light reciprocates between the sandwiched band module and the output mirror, the light passes between the pair of electrodes. The light is amplified. The light transmitted through the output mirror is output as output laser light to, for example, an exposure apparatus. Here, the function of the resonator is realized by the interbanding module and the output mirror, but the function of the resonator may be realized by another configuration.

The laser gas filled in the oscillation chamber 12 is, for example, a buffer gas such as neon gas or helium (for example, 90 to 95%), a rare gas (Kr, Ar, Xe) (for example, 5 to 9%), and a halogen gas (for example, 5 to 9%). It has an excitation gas composed of F ₂ ) (for example, 1 to 5%). For example, as the excitation gas, there are KrF, ArF, XeF, Ar / XeF and the like.
In the present embodiment, what is returned as the recycled gas to the oscillation chamber 12 is a main component buffer gas (for example, neon) containing a rare gas (for example, krypton, argon, argon / xenon) having the same component as the laser gas component. The halogen gas-containing main component buffer gas and the recycled gas may be mixed and then sent to the oscillation chamber 12.
The excimer laser oscillator 1 has a first laser gas supply line for sending the first laser gas to the oscillation chamber 12, a second laser gas supply line for sending the second laser gas, and a recycled gas line for sending the recycled gas. You may be doing it.
The first laser gas may be a halogen gas-containing main component buffer gas or a rare gas and a halogen gas-containing main component buffer gas.
The second laser gas may be a halogen gas-containing main component buffer gas or a rare gas and a halogen gas-containing main component buffer gas.
The first laser gas supply line and the second laser gas supply line are each equipped with a control valve, a gas flow meter, a gas flow rate adjusting unit, a pressure gauge, a pressure adjusting unit (for example, a pressure reducing valve), and the like, and laser gas is supplied to the oscillation chamber 12. At the time of supply, they are controlled by a control device, and laser gas having a predetermined pressure and a predetermined flow rate is supplied to the oscillation chamber.

In FIG. 1A, the first laser gas is supplied from the supply container 10 to the excimer laser oscillator 1 through the supply line L1 at a predetermined pressure (first pressure). A supply valve 101, a sluice valve 102 (may or may not be present), and a gas flow rate adjusting unit 104 are arranged with a supply sluice valve 103 on the supply line L1. The gas flow rate adjusting unit 104 has a gas flow meter and a gas flow rate adjusting valve, and adjusts the valve according to the measured value of the gas flow meter to control the gas flow rate. A gas flow meter, a pressure gauge, and a decompression adjusting unit may be arranged instead of the gas flow rate adjusting unit 104.
The control device of the excimer laser oscillator 1 controls, for example, to close the supply valve 101 and / or the supply sluice valve 103 when supplying only recycled gas to the oscillation chamber 12. The "first pressure" is set according to the specifications of the excimer laser oscillator 1, and is, for example, 300 KPa to 700 KPa.

Further, a second laser gas supply line (not shown) for supplying the second laser gas is provided so as to be connected to the supply line L1, the oscillation chamber 12, or the recycling line (L31, L6). Similar to the first laser gas supply line, various valves and a gas flow rate adjusting unit are arranged in the second laser gas supply line (not shown).
When the pressure of the first laser gas in the supply container 10 is larger than the first pressure, the pressure of the first laser gas is adjusted by a gas pressure reducing valve (not shown) arranged on the upstream side or the downstream side of the gas flow rate adjusting unit 104. It may be reduced to one pressure.
When the pressure is higher than the first pressure of the second laser gas in the supply container (not shown), the pressure of the second laser gas may be reduced to the first pressure by the gas pressure reducing valve (not shown).

(First impurity remover)
FIG. 1B shows a configuration example of the first impurity removing device 13 and the second impurity removing device 14.
The exhaust gas discharged from the oscillation chamber 12 is sent to the first impurity removing device 13 through the exhaust gas line L2. The exhaust gas is discharged at a second pressure that is above atmospheric pressure and below the first pressure. This second pressure is also set according to the specifications of the excimer laser oscillator 1. An exhaust pump (not shown) may be arranged in the exhaust gas line L2 to execute (or promote) exhaust gas emission.
The "second pressure" is, for example, 50 to 100 KPa. Impurities are mixed in the exhaust gas emitted. Examples of impurities include nitrogen, oxygen, carbon monoxide, carbon dioxide, water, CF ₄ , He, CH _{4, and the} like.
The control device of the excimer laser oscillator 1 has a laser gas supply / exhaust control unit (not shown), and the laser gas supply / exhaust control unit controls a control valve, a gas flow meter, a gas flow rate adjusting unit, a gas pressure reducing valve, and the like. Then, according to a predetermined rule (for example, periodic timing based on the operating time), the laser gas (exhaust gas) is discharged from the oscillation chamber 12, and the amount of the first laser gas, the second laser gas, and the recycling corresponding to the discharged amount are discharged. Supply any one or more of the gases.

The exhaust gas line L2 becomes a decomposition removal processing line in the first impurity removing device 13.
First, the exhaust gas is sent to the fluorine compound removing unit 131, and the fluorine compound which is a part of impurities is removed.
Next, it is sent to the buffer space 1321 and stored so that the exhaust gas becomes a constant amount. The buffer space 1321 has a function of storing a predetermined amount of exhaust gas and stably measuring impurities by the impurity concentration detecting unit 132 described later.
The impurity concentration in the exhaust gas is measured by the impurity concentration detecting unit 132 arranged inside the buffer space 1321. Here, for example, the concentration of CH ₄ is measured as an impurity. As the impurity concentration detecting unit 132, for example, gas chromatography, a heat conduction type concentration sensor, a semiconductor type concentration sensor, or the like can be used.

A discharge line L20 for discharging the exhaust gas from the buffer space 1321 to the outside air is provided. The discharge line L20 includes, for example, a pipe, a vent device for discharging outside air, and an automatic on-off valve 221.

A bypass line L21 branches from the decomposition removal processing line L2 downstream of the buffer space 1321. The bypass line L21 is configured to include, for example, piping and an automatic on-off valve 241.

The disassembly / removal processing line L2 includes, for example, a pipe, a gas flow rate measuring unit 212, and an automatic on-off valve 231. A mass flow meter can be used as the gas flow rate measuring unit 212. The replacement time determination unit (not shown) calculates the amount of impurities based on the measured value of the gas flow rate measuring unit 212 and the measured value of the impurity concentration detecting unit 132, and determines the predetermined reactant of the decomposition by-product removing unit 135. You may ask for the replacement time. The required replacement time may be output to an input / output interface or the like to notify the operator.

Further, in the decomposition removal processing line L2, a buffer container 133 is arranged on the downstream side of the automatic on-off valve 231 and has a configuration in which a predetermined amount of exhaust gas is stored. A decomposition device 134 that decomposes fluorocarbon (CF ₄ ), which is a part of impurities, into a decomposition by-product is arranged on the downstream side of the buffer container 133. In the present embodiment, the decomposition device 134 is a device that irradiates the exhaust gas with excimer laser light.
The decomposition by-product removing unit 135 is arranged on the downstream side of the decomposition device 134. In the present embodiment, the decomposition by-product is, for example, a fluorine compound, and the decomposition by-product produced by the decomposition apparatus 134 is reacted with a predetermined reactant (for example, a metal-based reactant or a gas absorption-based reactant). And remove it from the exhaust gas. The exhaust gas that has passed through the decomposition by-product removing unit 135 is called the first refined gas. The first purified gas is sent to the second impurity removing device 14 on the gas treatment line L3.
Further, as another embodiment, the gas flow rate measuring unit 212 may or may not be provided.

The determination of processing selection in this embodiment is as follows.
The impurity concentration detection unit 132 measures the concentration of CF _{4 in} the exhaust gas. In this case, when the concentration of CF ₄ is equal to or higher than the first threshold value (for example, 100 ppm), the process selection unit (not shown) selects the first process, and the concentration of CF ₄ is smaller than the first threshold value. When it is larger than (for example, 10 ppm) and less than the first threshold value, the process selection unit selects the second process, and when the concentration of CF ₄ is less than the second threshold value, the process selection unit selects the third process. ..

Further, as another embodiment, the impurity concentration detection unit 132 measures the concentrations of CF ₄ , N ₂ and He in the exhaust gas. In this case
(A) He concentration is equal to or higher than the third threshold value (for example, 1.0%).
(B) Either CF ₄ or N ₂ is equal to or higher than the first threshold value (for example, 100 ppm), or
(C) The He concentration is less than the third threshold value, either CF ₄ or N ₂ is equal to or greater than the second threshold value (for example, 10 ppm) and less than the first threshold value, and the concentration relationship is N ₂ > (1). / 2) When × CF ₄ , the process selection unit selects the first process.
(D) When the He concentration is less than the third threshold value, the concentration of N ₂ or CF ₄ is equal to or more than the second threshold value and less than the first threshold value, and the magnitude relationship of the concentration is N ₂ <(1/2) ×. When it is CF ₄ , the process selection unit selects the second process.
(E) When the He concentration is less than the third threshold value and the concentration of N ₂ or CF ₄ is less than the second threshold value, the process selection unit selects the third process.

The metal-based reactant is not limited to the above, and a gas-absorbing reactant may be used instead.

The control device, processing selection unit, control unit for various valves, and replacement time determination unit have hardware such as a CPU (or MPU), circuits, firmware, and a memory for storing software programs, and are associated with software. It may be configured to operate in collaboration.

(Second impurity remover)
The second impurity removing device 14 removes the first and second impurities from the first purified gas sent by the gas treatment line L3 to obtain the second purified gas. The gas treatment line L3 is configured to include, for example, piping, one or more automatic on-off valves.
In the gas treatment line L3, the compressor 141, the first removal unit 142, the second removal unit 143, and the refined gas buffer tank 144 are arranged in this order. The gas that has passed through the second removal unit 143 is called a second refined gas (also referred to as recycled gas).
Further, as another embodiment, a heat exchanger, an adjusting unit for adjusting the flow rate of the first purified gas, a flow meter for measuring the flow rate of the first purified gas, and a first purified gas are located upstream of the first removing unit 142. A pressure adjusting unit for adjusting the pressure may be provided. The heat exchanger lowers the temperature of the first purified gas to a predetermined temperature. The gas temperature (for example, 60 to 80 ° C.) that has been boosted and raised by the compressor 141 can be lowered to a predetermined temperature (for example, 15 to 35 ° C.), and for example, a temperature suitable for the removing action in various removing portions in the subsequent stage. Reduce the gas temperature to a range.
Further, as another embodiment, an adjusting unit for adjusting the flow rate of the second purified gas, a flow meter for measuring the flow rate of the second purified gas, and a flow meter on the downstream side of the second removing unit 142 or the downstream side of the refined gas buffer tank 144. A pressure adjusting unit for adjusting the pressure of the second refined gas may be provided.

The compressor 141 boosts the pressure of the first exhaust gas to the third pressure. The third pressure is, for example, a pressure that is about 50 KPa to 150 KPa higher than the first pressure. The pressure control unit (not shown) controls the pressure of the first refined gas based on the measured value of the pressure gauge incorporated in the compressor 141 or the pressure gauge arranged downstream of the compressor 141.

The first removing unit 142 is an oxygen scavenger filled with a manganese oxide reactant or a copper oxide reactant that removes oxygen from the first purified gas. Examples of the manganese oxide reactant include a reactant such as manganese monoxide MnO, a reactant of manganese dioxide MnO ₂ , and a manganese oxide reactant based on an adsorbent. Examples of the copper oxide reactant include a reactant such as copper oxide CuO and a copper oxide reactant based on an adsorbent.
The purified gas that has passed through the first removal unit 142 is sent to the second removal unit 143 through the pipe L4.

The second impurity is a component excluding the impurities contained most in the exhaust gas component, and examples thereof include nitrogen, carbon monoxide, carbon dioxide, water, CF ₄ , CH ₄ , and He. The CF ₄ may be removed (partially removed, completely removed) by the first impurity removing device, or may be bypassed and sent to the second impurity removing device.
The second removal unit 143 is a getter filled with a chemical adsorbent that removes impurities other than oxygen (for example, nitrogen, carbon monoxide, carbon dioxide, water, CH ₄ ).
The second purified gas that has passed through the second removing section 143 is a gas from which impurities other than oxygen and oxygen have been removed (a rare gas-containing main component buffer gas). The second refined gas is sent to the refined gas buffer tank 144 through the pipe L5.

The second refined gas in the refined gas buffer tank 144 is sent to the oscillation chamber 12 as recycled gas through the recycling line L6. The recycling line L6 has, for example, an automatic on-off valve that opens when the recycled gas is supplied, an adjusting unit that adjusts the recycling flow rate, a flow meter that measures the recycling gas flow rate, and a pressure adjustment that adjusts the recycling gas pressure. One or more of the units may be provided, and these may be controlled by the laser gas supply / emission control unit to supply the recycled gas to the oscillation chamber 12.

(Embodiment 2)
The excimer laser oscillator 1 of the second embodiment will be described with reference to FIGS. 2A and 2B. The configuration similar to the first embodiment may omit or simplify its description. As shown in FIG. 2A, the excimer laser oscillator 1 of the second embodiment has a configuration in which the first impurity removing device 13 is provided in the system and the second impurity removing device 14 is arranged outside the system.

As shown in FIG. 2B, the second impurity removing device 14 (compressor 141, first removing unit 142, second removing unit 143, purified gas buffer tank 144) is arranged outside the system of the excimer laser oscillator 1.

(Embodiment 3)
The excimer laser oscillator of the third embodiment will be described with reference to FIG. The same configurations as those of the first and second embodiments may omit or simplify the description. The difference from the first and second embodiments is that the configuration of the second impurity removing device 14 has a xenon removing unit 70 and an auxiliary xenon gas supply function. When xenon in the exhaust gas is removed as a component of the laser gas, it is easier to remove the second impurity by the second removing section 143. That is, the second impurity removing device 14 may be arranged either inside or outside the system of the excimer laser oscillator.

A xenon removing section 70 is arranged after the first removing section 142, where xenon is removed. The xenon removing unit 70 is a dexenon removing device filled with activated carbon. The purified gas that has passed through the xenon removing unit 70 is sent to the second removing unit 143.

A pressure reducing valve 151 and a gas flow rate adjusting unit 152 are arranged on the downstream side of the refined gas buffer tank 144. The pressure control unit (not shown) controls the pressure reducing valve 151 based on the measured values of the pressure gauge arranged on the downstream side of the pipe L5 or the pressure gauge incorporated in the pressure reducing valve 151, and the pressure of the second refined gas. To control. Since the second refined gas in the refined gas buffer tank 144 is a gas having a third pressure, the pressure is reduced to the same pressure (first pressure) as the laser gas in the oscillation chamber 12.

The refined gas flow rate adjusting unit 152 has a gas flow meter and a gas flow rate adjusting valve, and the refined gas control unit (not shown) adjusts the gas flow rate adjusting valve according to the measured value of the gas flow meter. The flow rate of the second refined gas is controlled. As a result, the supply amount of the second purified gas sent to the oscillation chamber 12 can be controlled to be constant. The refined gas flow rate adjusting unit 152 may be only a gas flow meter. Further, the arrangement of the refined gas flow rate adjusting unit 152 or the gas flow meter and the pressure reducing valve 151 may be reversed.

An auxiliary rare gas introduction line L7 that joins the pipe L5 is provided on the downstream side of the refined gas flow rate adjusting unit 152. The auxiliary rare gas introduction line L7 includes an auxiliary container 71 filled with a buffer gas (for example, neon) and an auxiliary rare gas of xenone, a supply valve (not shown), and an auxiliary rare gas pressure reducing valve (corresponding to an auxiliary rare gas pressure adjusting unit). 72, the auxiliary rare gas flow rate adjusting unit 73 is arranged in this order.

The pressure control unit (not shown) controls the auxiliary rare gas pressure reducing valve 72 based on the measured value of the pressure gauge arranged on the downstream side of the auxiliary rare gas introduction line L7, and controls the 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 is reduced to the first pressure.

The auxiliary rare gas flow rate adjusting unit 73 has a gas flow meter and a gas flow rate adjusting valve, and the refined gas control unit (not shown) adjusts the gas flow rate adjusting valve according to the measured value of the gas flow meter. , Control the flow rate of auxiliary rare gas. The refined gas control unit controls the flow rate of the auxiliary rare gas and the flow rate of the second refined gas so that the amount of the xenon-containing gas (main component neon) is the same as that of the laser gas (for example, argon, xenon, neon).

In the present embodiment, the recycled gas tank 145 for storing the recycled gas composed of the second refined gas and the auxiliary rare gas is arranged in the pipe L5. Automatic on-off valves may be provided on the inlet side and the outlet side of the recycled gas tank 145. The second refined gas and the auxiliary rare gas are mixed in the recycled gas tank 145 and stabilized at a constant concentration.

The recycled gas in the recycled gas tank 145 is sent to the oscillation chamber 12 through the recycling line L6. The recycling line L6 has, for example, an automatic on-off valve that opens when the recycled gas is supplied, an adjusting unit that adjusts the recycling flow rate, a flow meter that measures the recycling gas flow rate, and a pressure adjustment that adjusts the recycling gas pressure. One or more of the units may be provided, and these may be controlled by the laser gas supply / emission control unit to supply the recycled gas to the oscillation chamber 12.

(Embodiment 4)
The excimer laser oscillator of the fourth embodiment will be described with reference to FIG. The configuration similar to the third embodiment may omit or simplify its description. The difference from the third embodiment is that the auxiliary container 471 filled with the auxiliary rare gas of buffer gas (for example, neon) and xenon is housed in the laser gas tank cabinet 400. The first laser gas tank 10 is also housed in the laser gas tank cabinet 400. The second impurity removing device 14 may be arranged inside or outside the system of the excimer laser oscillator.

(Embodiment 5)
The excimer laser oscillator 1 of the fifth embodiment will be described with reference to FIG. The configuration similar to the first embodiment may omit or simplify its description. The difference from the first embodiment is that the first impurity removing device 13 includes a fluorine compound removing unit 131, an impurity concentration detecting unit 132, a buffer space 1321, a gas flow rate measuring unit 212, and an automatic on-off valve 231.
The first impurity removing device 13 may have only the fluorine compound removing unit 131, or may have only the impurity concentration detecting unit 132.

As the third impurity removing device 13a, the buffer container 133, the decomposition device 134, and the decomposition by-product removing unit 135 may or may not be provided.
A compressor 141 is arranged on the gas processing line L3 of the first refined gas, and is branched from the automatic on-off valve 252 and the gas processing line L3 between the compressor 141 and the automatic on-off valve 252 downstream of the compressor 141 and sent to the oscillation chamber 21. A branch line L31 is provided. A buffer tank (not shown) may be arranged on the upstream side of the compressor 141 to store a predetermined amount of purified gas.
Based on the result of the impurity concentration detection unit 132, the purified gas that has passed through the bypass line L21 or the first purified gas that has passed through the third impurity removing device 13a can be boosted and sent to the oscillation chamber 21. At this time, the automatic on-off valve 252 is closed, and the automatic on-off valve 251 arranged on the branch line L31 is opened. A heat exchanger may be arranged on the gas treatment line L3 or the branch line L31 to lower the temperature of the first purified gas to a predetermined temperature.

A refined gas buffer tank may be arranged at the branch line L31. The purified gas is sent to the oscillation chamber 12 as recycled gas through the branch line L31. The branch line L31 includes, for example, an automatic on-off valve that opens when gas is supplied, an adjusting unit that adjusts the gas flow rate, a flow meter that measures the gas flow rate, and a pressure adjusting unit that adjusts the gas pressure. One type or one or more types may be provided, and they may be controlled by the laser gas supply / discharge control unit to supply the gas to the oscillation chamber 12.

Further, as another embodiment, a separate branch line is arranged on the gas processing line L3 on the upstream side of the compressor 141, and the refined gas that has passed through the bypass line L21 or the third impurity removing device 13a has passed from this separate branch line. The purified gas can be sent to the oscillation chamber 21. A refined gas buffer tank may be arranged in a separate branch line. The separate branch line includes, for example, an automatic on-off valve that opens when gas is supplied, an adjustment unit that adjusts the gas flow rate, a flow meter that measures the gas flow rate, and a pressure adjustment unit that adjusts the gas pressure. One type or one or more types may be provided, and they may be controlled by the laser gas supply / discharge control unit to supply the gas to the oscillation chamber 12.

(Embodiment 6)
The excimer laser oscillator 1 of the sixth embodiment will be described with reference to FIG. The configuration similar to the fifth embodiment may omit or simplify its description. The difference from the fifth embodiment is that the third impurity removing device 13a is included in the second impurity removing device 14 and is arranged outside the system of the excimer laser oscillator 1.

(Another embodiment)
In the above embodiments 1 to 6, the discharge line L20 and the bypass line L21 may or may not be provided.
In the first to sixth embodiments, the first impurity removing device 13 may or may not be provided.
In the first to sixth embodiments, the second impurity removing device 14 may or may not be provided.
In the above embodiments 1 to 6, the bypass line L21 may be configured to send exhaust gas to the oscillation chamber 12 instead of sending exhaust gas to the subsequent process. In such a case, a buffer tank may be arranged on the bypass line L21. The purified gas is sent to the oscillation chamber 12 as recycled gas through the branch line L31. The bypass line L21 includes, for example, an automatic on-off valve that opens when gas is supplied, an adjusting unit that adjusts the gas flow rate, a flow meter that measures the gas flow rate, and a pressure adjusting unit that adjusts the gas pressure. One type or one or more types may be provided, and they may be controlled by the laser gas supply / discharge control unit to supply the gas to the oscillation chamber 12.

(Recycled gas refining method)
A recycled gas purification method executed in the system (inside the housing) of the excimer laser oscillator.
This is a recycled gas purification method, characterized in that the first impurity removing step of removing impurities in the exhaust gas discharged from the oscillation chamber is executed in the system of the excimer laser oscillator.
The first impurity removing step may include a fluorine compound removing step of removing a fluorine compound which is a part of impurities.
The first impurity removal step is
A decomposition process that decomposes fluorocarbon, which is a part of impurities, into decomposition by-products,
It may have a decomposition by-product removing step unit which reacts the decomposition by-product produced in the decomposition step with a predetermined reactant and removes it from the exhaust gas.
The first impurity removing step may include an impurity concentration measuring step for measuring the impurity concentration in the exhaust gas discharged from the oscillation chamber.

Recycled gas refining method
The second impurity removing step of further removing impurities from the first purified gas treated in the first impurity removing step may be further executed in the system of the excimer laser oscillator.
The second impurity removing step may include a step of stepping up the first purified gas to a predetermined pressure.
The second impurity removing step includes a first removing step of removing the first impurity from the first purified gas.
After the first removing step, a second removing step of removing the second impurities from the first purified gas may be provided.
The second impurity removing step is
When argon (Ar) is contained as the first rare gas and xenon (Xe) is contained as the second rare gas in the first purified gas.
After the second removal step, a xenon-containing recycled gas mixing step of mixing the second purified gas and the auxiliary xenon-containing neon gas may be provided.
The second impurity removing step is
After the pressurizing step, a heat exchange step of lowering the temperature of the first purified gas may be provided.

1 Excimer laser oscillator 11 High-voltage pulse generator 12 Oscillation chamber 13 First impurity remover 131 Fluorine compound remover 132 Impurity concentration detector 133 Buffer container 134 Decomposition device 135 Decomposition product remover 14 Second impurity remover 141 Compressor 142 First removal unit 143 Second removal unit 144 Purification gas tank

Claims (6)

The excimer laser oscillator with gas recycling function is
An oscillating chamber filled with a laser gas containing halogen gas, rare gas, and buffer gas.
A first impurity removing device for removing impurities in the exhaust gas discharged from the oscillation chamber is provided in the system of the excimer laser oscillator.
The first impurity removing device is
A decomposition device that irradiates the exhaust gas with excimer laser light, which decomposes fluorocarbon, which is a part of impurities, into a decomposition by-product containing a fluorine compound.
An excimer laser oscillator having a decomposition by-product removing unit that reacts a decomposition by-product containing a fluorine compound produced by the decomposition device with a predetermined reactant and removes it from the exhaust gas. The first impurity removing device is
The excimer laser oscillator according to claim 1, further comprising a fluorine compound removing unit for removing a fluorine compound which is a part of impurities, which is arranged upstream from the decomposition device. The first impurity removing device is
It has an impurity concentration detection unit that measures the impurity concentration of any one or more of CF ₄ , N ₂ , and He in the exhaust gas discharged from the oscillation chamber.
The excimer laser oscillator has a first process of discharging exhaust gas to the outside air based on the results measured by the impurity concentration detection unit, a second process of executing an impurity removal process containing a fluorine compound, and a subsequent process. The excimer laser oscillator according to claim 1 or 2, further comprising a process selection unit for selecting one of a third process of sending exhaust gas to the vehicle. The excimer laser oscillator is
Any of claims 1 to 3, further comprising a second impurity removing device in the system of the excimer laser oscillating device for further removing impurities containing at least oxygen from the first purified gas processed by the first impurity removing device. The excimer laser oscillator according to item 1. The second impurity removing device is
The first removing part that removes the first impurities from the first purified gas,
The excimer laser oscillator according to claim 4, wherein a second removing unit that removes second impurities from the first purified gas that has passed through the first removing unit is used. The second impurity removing device is
When argon (Ar) is contained as the first rare gas and xenon (Xe) is contained as the second rare gas in the first purified gas.
A xenon removing unit that removes the xenon,
The excimer laser oscillator according to claim 4 or 5, further comprising an introduction line for introducing an auxiliary xenon-containing neon gas to be mixed.

Images