JP7360539B2 - Fluorine detection in gas discharge light sources - Google Patents

Description

Cross-reference of related applications
[0001] This application claims priority to U.S. Application No. 62/893,377, filed August 29, 2019, entitled FLUORINE DETECTION IN A GAS DISCHARGE LIGHT SOURCE, the entirety of which is incorporated herein by reference. Incorporated into the specification.

[0002] The disclosed subject matter relates to the detection of fluorine in a gas mixture.

[0003] One type of gas discharge light source used in photolithography is known as an excimer light source or laser. Excimer light sources typically use a combination of one or more noble gases, such as argon, krypton, or xenon, and a reactive gas, such as fluorine or chlorine. The name excimer light source derives from the fact that under suitable conditions of electrical stimulation (supplied energy) and high pressure (of the gas mixture), pseudomolecules called excimers exist only in the excited state and generate amplified light in the ultraviolet range. This comes from the fact that it is generated.

[0004] Excimer light sources produce a light beam having a wavelength in the deep ultraviolet (DUV) range, which is used to pattern a semiconductor substrate (or wafer) in a photolithographic apparatus. Excimer light sources can be constructed with a single gas discharge chamber or with multiple gas discharge chambers.

[0005] In some general aspects, a method includes receiving at least a portion of a fluorine-containing gas mixture from a gas discharge chamber, reacting the fluorine in the portion of the gas mixture with a hydroxide; forming a new gas mixture containing oxygen and water, sensing the concentration of water in the new gas mixture, and estimating the concentration of fluorine in a portion of the gas mixture based on the sensed concentration of water. include.

[0006] Implementations may include one or more of the following features. For example, hydroxides can include alkaline earth metal hydroxides. The hydroxide may be free of alkali metals and carbon.

[0007] The gas mixture may be an excimer laser gas including at least a mixture of a gain medium and a buffer gas.

[0008] The method includes adjusting a relative concentration of fluorine in a gas mixture from a set of gas supplies based on an estimated concentration of fluorine in a portion of the gas mixture, and adjusting the adjusted gas mixture from the gas supply. It may also include performing a gas update by adding a gas to the discharge chamber. Gas renewal may be performed by filling the gas discharge chamber with a mixture of gain medium, buffer gas and fluorine. The gas discharge chamber may be filled with a mixture of a gain medium and a buffer gas by filling the gas discharge chamber with a gain medium comprising a noble gas and a halogen and a buffer gas comprising an inert gas. Noble gases may include argon, krypton, or xenon, halogens may include fluorine, and inert gases may include helium or neon. The gas discharge chamber is configured to add a mixture of a gain medium, a buffer gas, and fluorine to an existing gas mixture in the gas discharge chamber, or to add a mixture of at least a gain medium, a buffer gas, and fluorine to an existing gas mixture in the gas discharge chamber. It could be filled with a mixture of gain medium, buffer gas and fluorine by replacing it with . Gas updates may be performed by performing one or more of a gas refill scheme or a gas injection scheme.

[0009] A portion of the gas mixture may be received from the gas discharge chamber by receiving a portion of the gas mixture before a gas update to the gas discharge chamber is performed. Gas updating may include adding a gas mixture containing at least some fluorine to the gas discharge chamber from a gas supply set.

[0010] Gas updates may be performed by performing one or more of a gas refill scheme or a gas injection scheme.

[0011] A portion of the gas mixture may be received from the gas discharge chamber by withdrawing the gas mixture from the gas discharge chamber and directing the withdrawn gas mixture to a reaction vessel containing hydroxide. There is. The method may also include transferring the new gas mixture from the reaction vessel to the measurement vessel, and sensing the concentration of water in the new gas mixture detecting the concentration of water in the new gas mixture in the measurement vessel. including detecting. The concentration of water in the new gas mixture can be detected by exposing the sensor in the measurement container to the new gas mixture.

[0012] The method may also include discharging a new gas mixture from the measurement vessel after estimating the concentration of fluorine in the portion of the gas mixture.

[0013] The concentration of water in the new gas mixture may be detected by sensing the concentration of water in the new gas mixture without diluting a portion of the gas mixture with another material.

[0014] A portion of the gas mixture may react with the hydroxide to form an inorganic fluoride compound and water, thereby forming a new gas mixture containing water. Hydroxides may include calcium hydroxide, and inorganic fluoride compounds may include calcium fluoride.

[0015] The concentration of water in the new gas mixture may be detected by sensing the concentration of water in the new gas mixture only after a predetermined period of time after the initiation of the reaction.

[0016] A portion of the gas mixture may be exhaust gas, and a portion of the gas mixture reacts with hydroxide to form a new gas mixture containing water by removing fluorine from the exhaust gas. there is a possibility.

[0017] The concentration of fluorine in a portion of the mixed gas is estimated based only on the concentration of the detected water and the chemical reaction between fluorine and hydroxide in the portion of the mixed gas. may be estimated based on the concentration of

[0018] The concentration of fluorine in the portion of the gas mixture may be about 500-2000 parts per million.

[0019] The reaction of fluorine and hydroxide in a portion of a gas mixture to form a new gas mixture containing water can be stable.

[0020] Fluorine in a portion of the gas mixture reacts with hydroxide to create a linear and direct relationship between the concentration of fluorine in the portion of the gas mixture and the concentration of water in the new gas mixture. By performing correlated reactions, it is possible to form new gas mixtures containing water.

[0021] The method may also include sensing the concentration of oxygen in the new gas mixture, and estimating the concentration of fluorine in the portion of the gas mixture may additionally include sensing the concentration of oxygen. It may be based on

[0022] In another general aspect, a method includes performing a first gas update by adding a first gas mixture to a gas discharge chamber from a gas supply set, after the first gas update; removing at least a portion of the fluorine-containing gas mixture from the gas discharge chamber; reacting some of the fluorine in the removed gas mixture with a reactant to form a new gas mixture comprising oxygen and water; detecting the concentration of water in the sample; estimating the concentration of fluorine in a portion of the mixed gas extracted based on the detected concentration of water; adjusting the relative concentration of fluorine in the second gas mixture from the gas supply set based on the gas supply set; and adding the adjusted second gas mixture from the gas supply to the gas discharge chamber. including carrying out.

[0023] Implementations may include one or more of the following features. For example, the reactants may include hydroxide. The gas mixture within the gas discharge chamber may include an excimer laser gas including at least a mixture of a gain medium and a buffer gas.

[0024] The concentration of fluorine in a part of the mixed gas taken out can be determined by estimating the fluorine concentration in a part of the mixed gas taken out, without measuring the fluorine concentration in the part of the mixed gas taken out. , may be estimated based on the detected water concentration.

[0025] In another general aspect, an apparatus includes a detection device fluidly connected to each gas discharge chamber of the excimer gas discharge system and a control system coupled to the detection device. Each sensing device defines a reaction cavity containing hydroxide and fluidly connected to a gas discharge chamber, a vessel for receiving a fluorine-containing gas mixture from the gas discharge chamber into the reaction cavity, and a water sensor. including. The container allows a new gas mixture containing oxygen and water to be formed by reaction of the fluorine and hydroxide of the received gas mixture. The water sensor is fluidly connected to the new gas mixture and configured to sense an amount of water in the new gas mixture when fluidly connected to the new gas mixture. The control system receives the output of the water sensor, estimates the concentration of fluorine in the gas mixture received from the gas discharge chamber, and controls the gas supply system of the gas maintenance system based on the estimated concentration of fluorine in the gas mixture. determine whether to adjust the concentration of fluorine in the gas mixture from the gas supply system to the gas discharge chamber during gas updates to the gas discharge chamber. The gas maintenance system is configured to send a signal to the gas maintenance system instructing the gas maintenance system to adjust the concentration.

[0026] Implementations may include one or more of the following features. For example, each gas discharge chamber of an excimer gas discharge system may house an energy source and may contain a gas mixture including a gain medium and a fluorine-containing excimer laser gas.

[0027] The detection device may also include a measurement vessel fluidly connected to the reaction cavity of the reaction vessel and defining a measurement cavity configured to receive the fresh gas mixture. The water sensor may be configured to sense the amount of water in the fresh gas mixture within the measurement cavity.

[0028] The concentration of fluorine in the portion of the extracted gas mixture may be about 500-2000 ppm.

[0029] The excimer gas discharge system may include a plurality of gas discharge chambers, and the detection device may be fluidly connected to each gas discharge chamber of the plurality of gas discharge chambers. The detection device may include a plurality of vessels, each vessel defining a reaction cavity containing hydroxide, each vessel fluidly connected to one of the gas discharge chambers, and the detection device each defining a reaction cavity containing hydroxide. including a plurality of water sensors associated with one container. The detection device may include a plurality of vessels, each vessel defining a reaction cavity containing hydroxide, and each vessel fluidly connected to one of the gas discharge chambers, and the detection device may include a plurality of vessels, each vessel defining a reaction cavity containing hydroxide; Contains a single water sensor that is fluidly connected to all.

[0030] FIG. 2 is a block diagram of an apparatus including a detection device configured to measure the concentration of fluorine in a gas mixture within a chamber. [0031] FIG. 2 is a block diagram of the apparatus of FIG. 1 implemented as part of a deep ultraviolet (DUV) light source that produces a light beam that is directed into a photolithographic apparatus. [0032] FIG. 2 is a block diagram of an embodiment of a detection device of the apparatus of FIG. 1, where the detection device includes a fluorine sensor. [0033] FIG. 2 is a block diagram of an embodiment of the apparatus of FIG. 1 in which the detection device includes a buffer container. [0034] FIG. 3 is a block diagram of an embodiment of the apparatus of FIG. 1 in which the detection apparatus includes a plurality of reaction vessels, each reaction vessel being associated with one of a plurality of chambers. [0035] FIG. 3 is a block diagram of an embodiment of the apparatus of FIG. 2 showing details of an exemplary DUV light source. [0036] FIG. 7 is a block diagram of an example of a control system that is part of the DUV light source shown in FIG. 2 or FIG. 6. [0037] FIG. 3 is a block diagram of another embodiment of the apparatus of FIG. 1, in which the apparatus is implemented in conjunction with a fluorine scrubber. [0038] FIG. 3 is a flowchart of a procedure performed by a detection device to detect a concentration of fluorine in a gas mixture of a chamber. [0039] FIG. 10 is a flowchart of the procedure executed by the apparatus once the fluorine concentration has been estimated and the procedure of FIG. 9 has been completed. [0040] FIG. 10 is a flowchart of a procedure performed by a detection device in place of the procedure of FIG. 9 to estimate the concentration of fluorine in a gas mixture within a chamber.

[0041] Referring to FIG. 1, the apparatus 100 can measure the concentration of fluorine (F) in the gas mixture 107 within the chamber 110 without directly measuring the concentration of fluorine (F) in the gas mixture 107 using a commercially available fluorine sensor. includes a detection device 105 configured to measure or estimate . At room temperature, fluorine is a gas of diatomic molecules, represented by the molecular structure _F2 . Accordingly, the term "fluorine" as used herein refers to the molecular fluorine _F2 . The concentration of fluorine molecules _F2 in chamber 110 is in a range that is too high to allow direct detection of fluorine. For example, the concentration of fluorine within chamber 110 may be greater than about 500 ppm, about 1000 ppm, or up to about 2000 ppm. However, commercially available fluorine sensors typically saturate at 10 ppm, making it impractical to directly measure the concentration of fluorine in chamber 110 using commercially available fluorine sensors. Instead, the detection device 105 enables a chemical reaction that converts fluorine from the chamber 110 into one or more components (including water) that can be respectively detected and measured by commercially available sensors 115 of the detection device 116. The detection device 105 determines how much fluorine was present before the start of the chemical reaction based on the amount of water present after the chemical reaction (provided by the sensor 115) and also based on information about the chemical reaction. can be calculated or estimated.

[0042] In order to make this estimation accurate, the detection device 105 determines that the chemical reaction that converts fluorine from the chamber 110 into each component is a linear reaction, and that the concentration of fluorine before the start of the chemical reaction and the end of the chemical reaction are It can be assumed that there is a direct correlation between the concentration of water at Alternatively, the detection device 105 can assume that the conversion of fluorine is complete (therefore, there is no residual molecular fluorine F ₂ in the gas after the chemical reaction).

[0043] Apparatus 100 communicates with a gas maintenance system 120 that includes at least a gas supply system fluidly connected to chamber 110 via a conduit system 127. As discussed in more detail below, gas maintenance system 120 controls one or more gas supplies and which gases from these supplies are transferred into and out of chamber 110 via conduit system 127. a control unit (including a valve system) for

[0044] Apparatus 100 includes a controller 130 that receives the output from water sensor 115 and calculates how much fluorine was present before the start of the chemical reaction to estimate the amount of fluorine in gas mixture 107. . Controller 130 uses this information to determine whether the concentration of fluorine in gas mixture 107 needs to be adjusted. Controller 130 therefore determines how to adjust the relative amounts of gas in the supply of gas maintenance system 120 that are to be transferred into and out of chamber 110 based on this determination. Controller 130 sends a signal to gas maintenance system 120 instructing it to adjust the relative concentration of fluorine in gas mixture 107 during a gas update to chamber 110 .

[0045] Detection apparatus 105 includes a reaction vessel 135 that defines a reaction cavity 140 containing a hydroxide Σ(-OH) 145 (Σ is metal). Reaction cavity 140 is fluidly connected to chamber 110 via conduit 137 to receive a fluorine-containing gas mixture 150 from chamber 110 . Although not shown, one or more fluid control devices (such as valves) may be placed in conduit 137 to control the timing of directing gas mixture 150 into reaction cavity 140 and into reaction vessel 135. The flow rate can be controlled. In this manner, reaction cavity 140 allows chemical reaction of fluorine and hydroxide 145 in received gas mixture 150 to form new gas mixture 155. The interior of the reaction vessel 135 defining the reaction cavity 140 must be made of non-reactive materials so as not to inhibit or alter the chemical reaction between the fluorine and hydroxide 145 of the received gas mixture 150. No. For example, the interior of reaction vessel 135 can be made of a non-reactive metal such as stainless steel or Monel metal.

[0046] Water sensor 115 is fluidly connected to receive fresh gas mixture 155 and to sense the amount of water in fresh gas mixture 155. Water sensor 115 may be a commercially available water sensor capable of detecting water concentrations within a concentration range expected by chemical reactions. For example, water sensor 115 detects water in fresh gas mixture 155 in the range of 200-1000 ppm.

[0047] Water sensor 115 (and optionally oxygen sensor 117) may be inside a measurement cavity 175 of measurement vessel 170. Measurement cavity 175 is fluidly connected to reaction cavity 140 via conduit 177. Although not shown in FIG. 1, one or more fluid control devices (such as valves) may be placed in conduit 177 to control the timing of directing fresh gas mixture 155 to measurement cavity 175 and to The flow rate into the measurement container 170 can be controlled.

[0048] In some embodiments, water sensor 115 may be a hygrometer that measures the amount of water vapor, or humidity, within cavity 175. Instruments that measure humidity also typically measure temperature, pressure, mass, or mechanical or electrical changes in substances that absorb moisture, since these factors can also affect humidity. With calibration and calculation, these measurands can yield a humidity measurement. A hygrometer can be an electronic device that uses the condensing temperature (also called dew point), the point of full vapor saturation of a substance. A hygrometer may be a device that detects and measures changes in the capacitance or resistance of a substance to determine humidity. The hygrometer may be a resistance hygrometer that measures changes in the ability of a substance to hold an electrostatic charge. The hygrometer may be a capacitor-based hygrometer that measures changes in the ability of a substance to conduct electricity.

[0049] In some embodiments, although not required, the sensing device 116 may be an oxygen sensor 117 that detects oxygen in the fresh gas mixture 155 in the range of 200-1000 ppm. 117 included.

[0050] An example of oxygen sensor 117 suitable for this concentration range is an oxygen analyzer that uses a precision oxidized zirconia sensor for oxygen detection. Oxidized zirconia sensors include cells made from high purity, high density, stabilized zirconia ceramic. The oxidized zirconia sensor produces a voltage signal indicative of the oxygen concentration of the new gas mixture 155. The output of the oxidized zirconia sensor is also analyzed (eg, converted and linearized) by a high speed microprocessor within the oxygen sensor 117 to provide a direct digital readout for use by the controller 130. A conventional zirconium oxide cell includes a zirconium oxide ceramic tube plated with porous platinum electrodes on its inner and outer surfaces. Zirconia oxide sensors become oxygen ion conductive electrolytes when heated above a certain temperature (eg, 600C or 1112 degrees Fahrenheit). The electrode provides a catalytic surface for the conversion of oxygen molecules O ₂ to oxygen ions and oxygen ions to oxygen molecules. Oxygen molecules on the high concentration reference gas side of the cell acquire electrons that become ions that enter the electrolyte. At the same time, at the inner electrode, oxygen ions lose electrons and are released from the surface as oxygen molecules. When the oxygen concentration is different on each side of the oxidized zirconia sensor, oxygen ions move from the high concentration side to the low concentration side. This ion flux creates an electronic imbalance resulting in a DC voltage across the electrodes. This voltage is a function of the sensor temperature and the oxygen partial pressure (concentration) ratio on each side of the sensor. This voltage is then analyzed by a high speed microprocessor within oxygen sensor 117 for direct readout by controller 130.

[0051] The reason why the fluorine in the mixed gas 150 is reacted with the hydroxide 145 is because the chemical reaction between fluorine and hydroxide is a stoichiometrically simple chemical reaction that is easily carried out and controlled. be. Furthermore, the controlled stoichiometry of this chemical reaction is fixed. Furthermore, the chemical reaction between fluorine and hydroxide is a stable chemical reaction. A chemical reaction may be stable if it is not reversible and the components of the new gas mixture do not react with other components in the new gas mixture to form fluorine. One suitable chemical reaction between fluorine and hydroxide 145 in a gas mixture 150 that is stable and has a controlled stoichiometry will now be considered.

[0052] In some examples, hydroxide 145 is in particulate solid powder form. Further, the particulate form of hydroxide 145 can be tightly packed within the reaction vessel 135 (which may be a tube) to prevent movement of particles in the hydroxide 145 powder. The area or volume of the space inside the reaction vessel 135 outside the hydroxide 145 powder is considered as a pore, and by using the granular form of the hydroxide 145, a complete chemical reaction between the hydroxide 145 and fluorine can be prevented. It is possible to ensure that there is a large surface area that allows. In some embodiments, depending on the particular hydroxide, hydroxide 145 and reaction vessel 135 are maintained at room temperature and the reaction between hydroxide 145 and fluorine proceeds without the need for a catalyst.

[0053] Hydroxide 145 can fill reaction cavity 140 within reaction vessel 135. The shape of reaction vessel 135, and thus reaction cavity 140, is not limited to any particular form.

[0054] Hydroxide 145 includes metal Σ, which may be an alkaline earth metal. Furthermore, hydroxide 145 does not contain alkali metals and carbon. Therefore, hydroxide 145 may be calcium hydroxide [Ca(OH) ₂ ] (Σ is Ca in this example). Calcium hydroxide is a particulate solid form with sufficient pores to provide sufficient surface area to allow chemical reaction with fluorine gas. The spaces between the particles of calcium hydroxide are large enough to allow fluorine gas to flow into the calcium hydroxide to enable chemical reactions. For example, calcium hydroxide may be in the form of particles that are packed into the column, with the packing level depending on the fluorine concentration level in the gas mixture 150 being analyzed. A gas mixture 150 is passed (eg, flowed) through the hydroxide 145 to enable a chemical reaction between the fluorine and calcium hydroxide.

[0055] In the presence of fluorine gas (F ₂ ) in mixed gas 150, when the hydroxide is calcium fluoride Ca(OH) ₂ , the following two-step chemical reaction occurs.
1) 2F ₂ +Ca(OH) ₂ =CaF ₂ +OF ₂ +H ₂ O,
2) _OF2 + Ca(OH) ₂ = _CaF2 + _O2 + _H2O .
For every two molecules of fluorine (F ₂ ) that interact with molecules of calcium hydroxide [Ca(OH) ₂ ] 145, there are two molecules of an inorganic fluoride compound (calcium fluoride or CaF ₂ ) and one molecule of oxygen. A molecule (O ₂ ) and two water molecules (H ₂ O) are produced. This chemical reaction is linear and stoichiometrically simple. Therefore, if we focus only on fluorine and water, for every fluorine molecule F ₂ input into a chemical reaction, one water molecule H ₂ O is produced from the chemical reaction. Another way to write this is that for every mole of fluorine _F2 input into a chemical reaction, one mole of _H2O is produced from the chemical reaction. Therefore, if 2 moles of fluorine F ₂ are introduced into a chemical reaction, 2 moles of water H ₂ O will be released after the chemical reaction. This water is detected by water sensor 115. Thus, for example, controller 130 knows (from accessing data in stored memory) that the ratio of fluorine to water in this chemical reaction is 1:1, so sensor 115 indicates that 0.6 mol. of water is detected, controller 130 determines that 0.6 moles of fluorine were present in gas mixture 107. In other examples, the detection device 105 may assume that the conversion of fluorine is complete (therefore, there are no residual fluorine molecules _F2 in the gas after the chemical reaction). For example, this assumption may be a valid assumption if sufficient time has elapsed after the start of the chemical reaction.

[0056] In this example, if sensing device 116 also includes oxygen sensor 117, the measurement of oxygen concentration from oxygen sensor 117 can be used in combination with the measurement of water from water sensor 115. Therefore, if 4 moles of fluorine _F2 are introduced into a chemical reaction, 2 moles of oxygen _O2 will be released after the chemical reaction. This oxygen is detected by oxygen sensor 117. As an example, the controller 130 knows that the ratio of fluorine to oxygen in this chemical reaction is 2:1, so if 0.3 moles of oxygen are detected by the sensor 117, the controller It was determined that 0.6 mole of fluorine was present in the sample. Controller 130 uses data from both oxygen sensor 117 and water sensor 115 to determine the concentration of fluorine present in gas mixture 107 (since the weights or masses of oxygen, water, and fluorine are known). It can be estimated. For example, more accurate measurements of fluorine can be made using both data sets. As will be understood by those skilled in the art, the controller may also use additional calibrations and corrections (eg, to account for consumption or inefficient detection of fluorine, oxygen, or water).

[0057] In some examples, the chemical reaction between hydroxide 145 and fluorine in gas mixture 150 occurs under one or more specially designed conditions. For example, the reaction of hydroxide 145 with fluorine in gas mixture 150 can occur in the presence of one or more catalysts that change the rate of the chemical reaction but remain chemically unchanged at the end of the chemical reaction. There is sex. As another example, the reaction between hydroxide 145 and fluorine in gas mixture 150 may occur in a controlled environment, such as a temperature-controlled environment or a humidity-controlled environment.

[0058] Referring to FIG. 2, the apparatus 100 includes ultraviolet (UV) or deep ultraviolet (DUV) light beams that generate a light beam 211 that is directed to a photolithography apparatus 222 for patterning microelectronic features on a wafer, for example. It can be implemented within light source 200. Light source 200 includes a control system 290 connected to various elements of light source 200 to enable generation of light beam 211. Although control system 290 is shown as a single block, it may be comprised of multiple subcomponents, any one or more of which may be separated from other subcomponents or within light source 200. may be local to the element. Additionally, controller 130 can be considered part of control system 290 or part of apparatus 100.

[0059] In this example, the apparatus 100 is configured to calculate the concentration of fluorine within one or more of the gas discharge chambers 210 of the excimer gas discharge system 225 that generates the light beam 211 of the light source 200. ing. Although only one gas discharge chamber 210 is shown, the excimer gas discharge system 225 can include a plurality of gas discharge chambers 210, any one or more of which can be connected to the detection device 105 of the apparatus 100 and 2 is in fluid communication with other elements (such as optical elements, metrology devices, and electromechanical elements) for controlling characteristics of the light beam 211, which are not shown in FIG. Furthermore, only the components of light source 200 associated with device 100 are shown in FIG. For example, light source 200 may include a beam preparation system located at the output of last gas discharge chamber 210 to adjust one or more characteristics of light beam 211 directed to photolithographic apparatus 222.

[0060] Gas discharge chamber 210 houses an energy source 230 and contains gas mixture 207. Energy source 230 provides an energy source to gas mixture 207. Specifically, energy source 230 provides sufficient energy to gas mixture 207 to cause a population inversion to effectuate gain via stimulated emission within chamber 210. In some examples, energy source 230 is an electrical discharge provided by a pair of electrodes located within gas discharge chamber 210. In other examples, energy source 230 is an optical pumping source.

[0061] Gas mixture 207 includes a gain medium that includes a noble gas and a halogen, such as fluorine. During operation of the DUV light source 200, the fluorine in the gas mixture 207 in the gas discharge chamber 210 (which provides the gain medium for optical amplification) is consumed, thus reducing the amount of optical amplification over time, so that the light source 200 The characteristics of the generated light beam 211 change. The photolithography apparatus 222 attempts to maintain the concentration of fluorine in the gas mixture 207 within the gas discharge chamber 210 within a certain tolerance relative to the concentration of fluorine set in the initial gas refill procedure. To this end, additional fluorine is periodically added to the gas discharge chamber 210 under the control of the gas maintenance system 120. Since fluorine consumption varies from gas discharge chamber to gas discharge chamber, closed loop control is used to determine the amount of fluorine introduced or injected into the gas discharge chamber 210 at each time. The apparatus 100 is used to determine the concentration of fluorine remaining in the gas discharge chamber 210 and is therefore used throughout the scheme to determine the amount of fluorine to be introduced or injected into the gas discharge chamber 210.

[0062] As mentioned above, gas mixture 207 includes a gain medium that includes a noble gas and fluorine. Gas mixture 207 may also include other gases, such as buffer gases. The gain medium is the laser-active entity within the gas mixture 207 and may be composed of single atoms, molecules, or pseudomolecules. Thus, by pumping the gas mixture 207 (and thus the gain medium) with a discharge from the energy source 230, a population inversion occurs in the gain medium via stimulated emission. As mentioned above, the gain medium typically includes a noble gas and a halogen, and the buffer gas typically includes an inert gas. Noble gases include, for example, argon, krypton, or xenon. Halogen includes, for example, fluorine. Inert gases include, for example, helium or neon. The gases other than fluorine in gas mixture 207 are inert (noble or noble gases), so the only chemical reaction that occurs between gas mixture 150 and hydroxide 145 is between the fluorine and water in gas mixture 150. It is assumed that the reaction is between the oxide 145 and the oxide 145.

[0063] Referring again to FIG. 1, gas maintenance system 120 is a gas management system for regulating characteristics, such as the relative concentrations or pressures of components in gas mixture 107 or 207.

[0064] Referring to FIG. 3, in some embodiments where the sensing device includes an oxygen sensor 117 used in conjunction with a water sensor 115 to determine or estimate the concentration of fluorine in the gas mixture 107, the device is device 300. , the detection device 105 is a detection device 305 that includes a fluorine sensor 360 fluidly connected to the reaction cavity 140 and configured to determine when the concentration of fluorine in the fresh gas mixture 155 falls below a lower limit. Fluorine sensor 360 may be a commercially available fluorine sensor that saturates above a certain concentration of fluorine that is too low to be used for direct measurement of fluorine in gas mixture 150. However, because the fluorine sensor 360 has a minimum detection threshold, it can be used to detect when the concentration of fluorine in the fresh gas mixture 155 falls below a lower limit. For example, fluorine sensor 360 may be saturated at a concentration of 10 ppm, but has a minimum detection threshold of approximately 0.05 ppm, and after the concentration of fluorine in fresh gas mixture 155 falls below 0.1 ppm, Detection of fluorine in 155 can begin.

[0065] Controller 130 is configured as a controller 330 that receives the output from fluorine sensor 360. Controller 330 includes a module that interacts with a flow control device 365 in the line that conveys fresh gas mixture 155 to oxygen sensor 117. Flow control device 365 may be a device such as a gate valve or other fluid control valve.

[0066] The controller 330 controls the flow of the new gas mixture 155 to the oxygen sensor 117 only when determining from the output of the fluorine sensor 360 that the concentration of fluorine in the new gas mixture 155 is below a lower limit value (for example, 0.1 ppm). A signal is sent to the flow control device 365 to enable the flow rate control device 365. In this way, oxygen sensor 117 is exposed to fresh gas mixture 155 only when the concentration of fluorine is below the lower limit, thereby protecting oxygen sensor 117 from unacceptable levels of fluorine. The lower limit value may be a value determined based on the damage threshold of the oxygen sensor 117. Therefore, a fluorine concentration higher than the lower limit may cause damage to the oxygen sensor 117. The lower limit value may be a value determined based on the error threshold of the oxygen sensor 117. Therefore, at a fluorine concentration higher than the lower limit, measurement errors may affect the accuracy of the oxygen sensor 117.

[0067] Detection device 305 also includes a measurement vessel 370 fluidly connected to reaction cavity 140 of reaction vessel 135. Measurement vessel 370 defines a measurement cavity 375 configured to receive fresh gas mixture 155. Additionally, water sensor 115 and oxygen sensor 117 are housed within measurement cavity 375. Measuring container 370 contains a fresh gas mixture 155 that enables water sensor 115 to sense the concentration of water in fresh gas mixture 155 and enables oxygen sensor 115 to sense the concentration of oxygen in fresh gas mixture 155. Any container that can be used. The interior of the measurement vessel 370, which defines the measurement cavity 375, must be made of non-reactive material so as not to change the composition of the fresh gas mixture 155. For example, the interior of measurement vessel 370 may be made of non-reactive metal.

[0068] Referring to FIG. 4, in some embodiments, the apparatus 100 is designed as an apparatus 400 in which the detection apparatus 105 includes a buffer vessel 470 that decouples the flow rate of the exhaust from the chamber 110 from the flow rate required for the reaction vessel 135. The detection device 405 is designed as a detection device 405 including the following. In this manner, buffer vessel 470 allows fluorine measurements via detection device 405 without affecting the steady state operation of gas exchange performed by gas maintenance system 120.

[0069] In one example, the concentration of fluorine within chamber 110 is approximately 1000 ppm, the volume of chamber 110 is 36 liters (L), and the pressure within chamber 110 is between 200 and 400 kilopascals (kPa). The internal cavity of buffer vessel 470 has a volume of approximately 0.1 L and a pressure of 200-400 kPa. The measurement cavity 175 has a volume of 0.1 L, a pressure of approximately 200-400 kPa, a concentration of water of 1000 ppm, and a concentration of oxygen of approximately 500 ppm. After the water sensor 115 performs a water concentration measurement (optionally, the oxygen sensor 117 performs an oxygen concentration measurement) and outputs the data to the controller 130, the measurement cavity 175 is emptied in a controlled manner. There is a possibility that

[0070] As described above with reference to FIG. 1, apparatus 100 is configured to measure or estimate the concentration of fluorine in gas mixture 107 within chamber 110. In some embodiments, as shown in FIG. 5, device 100 is designed as device 500, and detection device 105 is arranged in each chamber 510_1, 510_2, . ．． ．． Gas mixtures 507_1, 507_2, . ．． ．． 507_i is designed as a detection device 505 configured to measure or estimate the concentration of fluorine in 507_i. Here, i is an integer greater than 1. The detection device 505 includes each chamber 510_1, 510_2, . ．． ．． Separate or dedicated sensing devices 516_1, 516_2, . ．． ．． There is 516_i. In this way, each of the sensing devices 516_1, 516_2, . ．． ．． 516_i to each chamber 510_1, 510_2, . ．． ．． The fluorine concentration within 510_i can be measured.

[0071] The detection device 505 is connected to a gas maintenance system 520 that connects each conduit system 527_1, 527_3, . ．． ．． 527_i to each chamber 510_1, 510_2, . ．． ．． 510_i includes a gas supply system fluidly connected to 510_i. The gas maintenance system 520 includes one or more gas supplies and routes gases from these supplies to each chamber 510_1, 510_2, . . . via a master conduit system 527. ．． ．． 510_i. The detection device 505 is connected to each chamber 510_1, 510_2, . ．． ．． 510_i to each conduit 537_1, 537_2, . ．． ．． A mixed gas (containing fluorine) 550_1, 550_2, . ．． ．． Each reaction vessel 535_1, 535_2, . ．． ．． 535_i. Next, each reaction container 535_1, 535_2, . ．． ．． The received mixed gases 550_1, 550_2, . ．． ．． Fluorine and hydroxide of 550_i 545_1, 545_2, . ．． ．． A new gas mixture 555_1, 555_2, . ．． ．． 555_i to each of the sensing devices 516_1, 516_2, . ．． ．． 516_i.

[0072] Detection device 505 includes gas maintenance system 520 and detection devices 516_1, 516_2, . ．． ．． It also includes a controller 530 connected to each of the 516_i. Similar to controller 530, controller 530 includes sensing devices 516_1, 516_2, . ．． ．． 516_i, and the reaction vessels 535_1, 535_2, . ．． ．． 535_i by calculating or estimating how much fluorine was present before the start of the chemical reaction in each gas mixture 507_1, 507_2, . ．． ．． Estimate the amount of fluorine in 507_i.

[0073] In other embodiments, all chambers 510_1, 510_2, . ．． ．． It is possible to use a single sensing device 516 that measures fluorine in 510_i. However, this means that the detection device 505 is connected to the chambers 510_1, 510_2, . ．． ．． 510_i and the detection device 505, including suitable piping between the chambers 510_1, 510_2, . ．． ．． This is the case if crosstalk between the measurements performed by the sensing device 516 for each of the 510_i is prevented. Additionally, the single sensing device 516 design is capable of functioning because gas exchange is performed in only one chamber 510 at a time, and thus the controller 530 detects fluorine in a single chamber 510 at any time. This is the case when it is possible to measure

[0074] Referring to FIG. 6, an exemplary DUV light source 600 incorporating a detection device 605, such as detection device 105 of FIG. 1, FIG. 3, FIG. 4, or FIG. It is shown. DUV light source 600 includes an excimer gas discharge system 625 that is a two-stage pulse output design. Gas discharge system 625 has two stages. That is, a first stage 601 is a main oscillator (MO) that outputs a pulse amplified light beam 606, and a second stage 602 is a power amplifier (PA) that receives the light beam 606 from the first stage 601. . The first stage 601 includes an MO gas discharge chamber 610_1, and the second stage 602 includes a PA gas discharge chamber 610_2. The MO gas discharge chamber 610_1 includes two elongated electrodes 630_1 as its energy source. Electrode 630_1 provides a source of energy to gas mixture 607_1 within chamber 610_1. The PA gas discharge chamber 610_2 includes two elongated electrodes 630_2 as its energy source, which provide a source of energy to the gas mixture 607_2 within the chamber 610_2.

[0075] MO 601 provides a light beam 606 (which can be referred to as a seed light beam) to PA 602. The MO gas discharge chamber 610_1 contains a gas mixture 607_1 containing a gain medium in which amplification occurs, and the MO 601 has a spectral characteristic selection system 680 on one side of the MO gas discharge chamber 610_1 and a second side of the MO gas discharge chamber 610_1. It also includes an optical feedback mechanism such as an optical resonator formed between the output coupler 681 on the side.

[0076] PA gas discharge chamber 610_2 contains a gas mixture 607_2 that includes a gain medium 607_2 in which amplification occurs when seeded with seed light beam 606 from MO 601. If the PA 602 is designed as a regenerative ring resonator, it is described as a power ring amplifier (PRA), in which case sufficient optical feedback may be provided from the ring design. The PA 602 includes a beam return 682, which returns the light beam (eg, by reflection) into the PA gas discharge chamber 610_2 to form a circular closed loop path. In this path, the input to the ring amplifier intersects the output from the ring amplifier at beam combiner 683.

[0077] MO 601 allows fine tuning of spectral parameters such as center wavelength and bandwidth with relatively low output pulse energy (compared to the output of PA 602). The PA receives the seed light beam 606 from the MO 601 and amplifies its output to obtain the necessary power in the output light beam 211 for use in an output device such as the photolithography apparatus 222. Seed light beam 606 is amplified by passing through PA 602 repeatedly, and the spectral characteristics of seed light beam 606 are determined by the configuration of MO 601 .

[0078] The gas mixture 607_1, 607_2 used in each gas discharge chamber 610_1, 610_2 is suitable for producing an amplified light beam (such as a seed light beam 606 and an output light beam 211) around the required wavelength and bandwidth. It may be a combination of gases. For example, the gas mixtures 607_1, 607_2 may include argon fluoride (ArF), which emits light at a wavelength of approximately 193 nanometers (nm), or krypton fluoride (KrF), which emits light at a wavelength of approximately 248 nm. .

[0079] Detection apparatus 605 includes a gas maintenance system 620, which is a gas management system for excimer gas discharge system 625, and specifically for gas discharge chambers 610_1 and 610_2. Gas maintenance system 620 includes one or more gas sources 651A, 651B, 651C, etc. (such as a sealed gas container or cylinder) and a valve system 652. One or more gas sources 651A, 651B, 651C, etc. are connected to MO gas discharge chamber 610_1 and PA gas discharge chamber 610_2 via a valve set in valve system 652. In this way, gas can be injected into each gas discharge chamber 610_1 or 610_2 with specific relative component amounts in the gas mixture. Although not shown, gas maintenance system 620 may also include one or more other components such as flow restrictors, exhaust valves, pressure sensors, gauges, and test ports.

[0080] Each of the gas discharge chambers 610_1 and 610_2 contains a mixture of gases (gas mixtures 607_1, 607_2). As an example, the gas mixtures 607_1, 607_2 contain halogens, such as fluorine, and other gases, such as argon, neon, and possibly others, at various partial pressures that add up to a total pressure. For example, if the gain medium used in the gas discharge chambers 610_1, 610_2 is argon fluoride (ArF), the gas source 651A may include one or more of the halogen fluorine, the noble gas argon, and a buffer gas. contains a mixture of gases, including noble gases (which may be inert gases such as neon). This type of mixture in gas source 651A can be referred to as a trimix since it contains three types of gas. In this example, another gas source 651B may contain a mixture of gases including argon and one or more other gases, but no fluorine. This type of mixture in gas source 651B can be referred to as a bimix since it contains two types of gas.

[0081] The gas maintenance system 620 may include a valve controller 653, which directs the valve system 652 to transfer gas from a particular gas source 651A, 651B, 651C, etc. into the gas discharge chambers 610_1, 610_2 in a gas update. The valve system 652 is configured to send one or more signals to the valve system 652 . Gas renewal may be a refill of the gas mixture 607 in the gas discharge chamber, replacing the existing gas mixture in the gas discharge chamber with a mixture of at least a gain medium, a buffer gas, and fluorine. Gas renewal can be an injection scheme that adds a mixture of gain medium, buffer gas, and fluorine to the existing gas mixture in the gas discharge chamber.

[0082] Alternatively or additionally, valve controller 653 may send one or more signals to valve system 652 that cause valve system 652 to evacuate gas from discharge chambers 610_1, 610_2 when necessary. , such extracted gas may be discharged into a gas dump represented by 689. Alternatively, in some embodiments, the extracted gas may be provided to a detection device 605, as shown in FIG.

[0083] During operation of the DUV light source 600, the fluorine of the argon fluoride (or krypton) molecules (providing the gain medium for optical amplification) in the gas discharge chambers 610_1, 610_2 is consumed, thus reducing the optical amplification over time. , and thus the energy of the light beam 211 used by the photolithographic apparatus 222 for wafer processing. Furthermore, during operation of the DUV light source 600, contaminants may enter the gas discharge chambers 610_1, 610_2. Therefore, it is necessary to inject gas into the gas discharge chambers 610_1, 610_2 from one or more gas sources 651A, 651B, 651C, etc. to flush out contaminants or to replenish lost fluorine.

[0084] The reason why multiple gas sources 651A, 651B, 651C, etc. are required is because the fluorine in gas source 651A is at a particular partial pressure that is generally higher than desired for laser operation. To add fluorine to gas chamber 610_1 or 610_2 at a desired lower partial pressure, the gas in gas source 651A may be diluted, and for this purpose the halogen-free gas in gas source 651B is used. There is a possibility that

[0085] Although not shown, the valves of valve system 652 may include multiple valves assigned to each of gas discharge chambers 610_1 and 610_2. For example, an injection valve may be used that allows gas to flow into and out of each gas discharge chamber 610_1, 610_2 at a first flow rate. As another example, a chamber filling valve is used for each gas discharge chamber 610_1, 610_2 that allows gas to enter and exit at a second flow rate that is different (e.g., faster) than the first flow rate. there is a possibility.

[0086] When a refilling scheme is performed for a gas discharge chamber 610_1 or 610_2, for example, the gas discharge chamber 610_1 or 610_2 is emptied (by withdrawing the gas mixture into the gas dump 689) and then the gas discharge chamber 610_1 is Alternatively, all of the gas in gas discharge chamber 610_1 or 610_2 is replaced by refilling 610_2 with a new gas mixture. Refilling is performed with the aim of obtaining a specific pressure and concentration of fluorine within the gas discharge chamber 610_1 or 610_2. If the injection scheme is carried out for the gas discharge chamber 610_1 or 610_2, the gas discharge chamber is not emptied or only a small amount is evacuated before the gas mixture is injected into the gas discharge chamber. In both types of gas renewal, the detection device 605 (designed similarly to the detection device 105) receives a portion of the extracted gas mixture as a gas mixture 150, which is analyzed in the detection device 605. , the concentration of fluorine in the gas discharge chamber 610_1 or 610_2 can be determined to determine how to perform the gas update.

[0087] Valve controller 653 cooperates with detection device 605 (specifically, controller 130 within detection device 605). Additionally, valve controller 653 may cooperate with other control modules and subcomponents that are part of control system 690. This will be considered next.

[0088] Referring to FIG. 7, a control system 790 (which may be control system 290 or 690) that is part of a DUV light source (such as light source 200 or 600) is shown in a block diagram. Details are provided about the control system 790 in relation to aspects of the detection device 105/605 and the methods for gas control and fluorine concentration estimation described herein. Additionally, control system 790 may also include other features not shown in FIG. Control system 790 generally includes one or more of digital electronic circuitry, computer hardware, firmware, and software.

[0089] Control system 790 includes memory 700, which may be read-only memory and/or random access memory. Storage devices suitable for tangibly embodying computer program instructions and data include, by way of example, semiconductor memory devices such as EPROM, EEPROM, and flash memory devices, magnetic disks such as internal hard disks and removable disks, magneto-optical disks, and all forms of non-volatile memory, including CD-ROM disks. Control system 790 may also include one or more input devices 705 (such as a keyboard, touch screen, microphone, mouse, handheld input device, etc.) and one or more output devices 710 (such as speakers or monitors).

[0090] Control system 790 includes one or more programmable processors 715 and one or more computer program products 720 tangibly embodied in a machine-readable storage device that is executed by a programmable processor (such as processor 715). . One or more programmable processors 715 may execute a program of instructions to perform desired functions, each operating on input data and generating appropriate outputs. Generally, processor 715 receives instructions and data from memory 700. All of the foregoing may be supplemented or incorporated into specially designed ASICs (Application Specific Integrated Circuits).

[0091] Control system 790 also includes controllers 130, 330, 530 (represented by box 730 in FIG. 7) of detection device 105, and valve controller 653 of gas maintenance system 620, among other components or modules. and an associated gas maintenance module 731. Each of these modules may be a set of computer program products executed by one or more processors, such as processor 715. Additionally, either controller/module 730, 731 can access data stored within memory 700.

[0092] Connections between controllers/features/modules within control system 790 and between controllers/features/modules within control system 790 and other components of apparatus 100, which may be DUV light source 600. The connection between can be wired or wireless.

[0093] Although only a few modules are shown in FIG. 7, control system 790 may also include other modules. Additionally, although control system 790 is depicted as a box with all components appearing to be located in the same location, control system 790 may also be comprised of components that are physically separated from each other in space or time. It is. For example, controller 730 may be physically co-located with sensing device 116 or gas maintenance system 120. As another example, gas maintenance module 731 may be physically co-located with valve controller 653 of gas maintenance system 620 and may be remote from other components of control system 790.

[0094] Control system 790 may further include a lithography module 732 that receives instructions from a lithography controller of photolithographic apparatus 222, such as instructions to measure or estimate the concentration of fluorine in gas mixture 107 of chamber 110. There is.

[0095] Referring to FIG. 8, in some embodiments, the apparatus 100 is designed as an apparatus 800 in which the detection apparatus 105 operates in parallel with a fluorine scrubber 804 in fluid communication with a gas maintenance system 820. It is designed as device 805. Fluorine scrubber 804 is used in conjunction with gas maintenance system 820 to clean chamber 110 by chemically reacting the fluorine in gas mixture 807 to form a chemical that can be safely disposed of, e.g., via exhaust. The gas mixture 807 is suitably vented.

[0096] A portion of the gas mixture 150 withdrawn from the gas maintenance system 820 is directed to a buffer vessel 870 and then to another fluorine scrubber 835 containing hydroxide 845. The fluorine in the gas mixture 150 chemically reacts with the hydroxide 845 in the fluorine scrubber 835 (as discussed above) and is converted to a new gas mixture 155 that includes oxygen. The new gas mixture 155 is directed to the sensing device 116 where it is sensed. Controller 130 estimates the concentration of oxygen and fluorine in gas mixture 150 and gas mixture 107 and determines how to adjust gas maintenance system 820 to perform the gas update. In this example, gas maintenance system 820 includes a valve system 852 fluidly connected to trimix source 851A and bimix source 851B. Various control valves 891 are placed along the line to control the flow rate and the amount of gas directed through the line.

[0097] Referring to FIG. 9, a procedure 900 is performed by the apparatus 100 to detect the concentration of fluorine in the gas mixture 107 of the chamber 110. Although reference is made to the apparatus of FIG. 1, the procedure 900 also applies to the apparatuses described with reference to FIGS. 2-8. Detection device 105 receives a portion of fluorine-containing gas mixture 150 from gas discharge chamber 110 (905). Fluorine in gas mixture 150 chemically reacts with hydroxide 145 to form a new gas mixture 155 that includes water (910). The water concentration in the new gas mixture 155 is sensed (915), for example by water sensor 115. Furthermore, the concentration of fluorine in the mixed gas 150 is estimated based on the detected concentration of water (920). For example, controller 130 can estimate the concentration of fluorine in mixed gas 150 based on the output from water sensor 115.

[0098] By withdrawing (releasing under pressure) the gas mixture 107 from the chamber 110, the detection device 105 may receive the gas mixture 150 (905). For example, gas maintenance system 120 may include a group of valves that allow gas mixture 107 to be withdrawn from chamber 110 and then directed to detection device 105 as gas mixture 150. The pressure within chamber 110 can be used to pressurize reaction vessel 135 or buffer vessel 470, for example by creating a negative pressure using a series of valves and a vacuum pump, and gas mixture 107 is transferred from chamber 110 to detection device 105. push it out. The amount of mixed gas 150 required within reaction vessel 135 may be determined based on the need for water sensor 115 to obtain accurate and stable readings. The limiting factor on the amount of gas mixture 150 is the fluorine conversion capacity of hydroxide 145 within reaction cavity 140. For example, while it is desirable to obtain accurate readings from water sensor 115, it is also desirable to minimize total gas flow so that hydroxide 145 can have the longest useful life.

[0099] The gas mixture 150 received 905 by the detection device 105 may be the gas mixture 150 exhausted from the chamber 110 to the fluorine scrubber, and thus the gas mixture 150 may be considered an exhaust gas. . Such an embodiment is shown in FIG. 8, where fluorine in gas mixture 150 chemically reacts with hydroxide 845 in fluorine scrubber 835 and is converted to a new gas mixture 155 that includes oxygen.

[0100] Procedure 900 may be performed in anticipation of a gas update, such as a gas refill or gas injection. For example, a first gas update may be performed by adding a first gas mixture to chamber 110 from gas maintenance system 120, and after using chamber 110 for a period of time, procedure 900 may be performed. There is. After performing procedure 900, a second gas update may be performed by adding a conditioned second gas mixture to chamber 110 from gas maintenance system 120. The concentration of fluorine (or amount of fluorine) in the conditioned second gas mixture may be based on measurements made by procedure 900.

[0101] Fluorine can be chemically reacted with hydroxide 145 by forming an inorganic fluoride compound and water and oxygen (910). This inorganic fluoride compound (present in the new gas mixture 155) does not interact with the water sensor 115.

[0102] After chemically reacting the fluorine with the hydroxide 145 to form a new gas mixture 155 (910), the new gas mixture 155 is transferred from the reaction vessel 135 into the measurement vessel 170 to form the new gas mixture 155. The concentration of water therein can be detected (915). Thus, by exposing the sensor 115 in the measurement container 170 to the new gas mixture 155, the concentration of water in the new gas mixture 155 can be detected (915). The concentration of water in the new gas mixture 155 is sensed (915) without the need to dilute the gas mixture 150 with another material.

[0103] Additionally, sensing (915) of the concentration of water in the new gas mixture 155 may wait until a predetermined time has elapsed after the initiation of the chemical reaction (910), or may only occur after a predetermined time has elapsed. May be appropriate. This will ensure that sufficient fluorine in the gas mixture 150 has been converted to water and inorganic fluoride compounds before exposing the water sensor 115 to the new gas mixture 155. Depending on the relative amounts of fluorine in the gas mixture 150 and the total amount of hydroxides 145, it may take seconds or minutes to completely convert the fluorine to water.

[0104] In some embodiments, the gas mixture 150 is flowed over or through the hydroxide 145 at a low flow rate (e.g., about 0.1 slpm or less) to provide a specific flow rate of the new gas mixture 155. By forming a chemical reaction (910) may be carried out. In this case, water can be detected continuously (915). The concentration of fluorine can be estimated (920) by integrating the sensed water measurements (915) over a period of time or if the sensed water measurements (915) reach a steady state.

[0105] Estimate fluorine in the new gas mixture 155 based on the detected water concentration (915) and further based on knowledge of the chemical reaction that converts fluorine in the gas mixture 150 to water (920). .

[0106] Upon completion of procedure 900 (i.e., after estimating (920) the concentration of fluorine in gas mixture 150), new gas mixture 155 is discharged (removed) from measurement vessel 170 and a new batch of gas mixture 150 is prepared. It becomes possible to perform procedure 900 again for .

[0107] Referring to FIG. 10, once the fluorine concentration is estimated (920) and procedure 900 is completed, procedure 1000 is performed by apparatus 100. The gas maintenance system 120 receives output from the controller 130 of the detection device 105 and determines the relative amount of fluorine in the gas mixture from the gas supply set (e.g., gas sources 651A, 651B, 651C) based on the estimated fluorine concentration. Adjust the concentration (1005). Gas maintenance system 120 performs gas renewal by adding a conditioned gas mixture to chamber 110 via conduit system 127 until the pressure within chamber 110 reaches the required level (1010). By monitoring the timing of valves within gas maintenance system 120, gas updates can be completed and tracked.

[0108] For example, referring to FIG. 2, gas renewal (1010) may include filling a gas discharge chamber 210 with a mixture of a gain medium, a buffer gas, and fluorine. The gain medium includes a noble gas and fluorine, and the buffer gas includes an inert gas. It is possible to delay performing the gas update (1010) with respect to when the fluorine concentration estimation (900) is performed. In some embodiments, if the controller 130 determines that the concentration of fluorine in the gas mixture 107 has fallen below an acceptable level, the adjustment (1005) and gas update (1010) may be performed immediately after the estimation (900). can. In some embodiments, fluorine adjustment (1005) may be delayed until the concentration of fluorine in gas mixture 107 is determined to be below an acceptable level. For example, if controller 130 determines that the concentration of fluorine in gas mixture 107 is still high, but that apparatus 100 must perform a gas update for other reasons, increasing the level of fluorine in gas mixture 107 It is possible to perform a gas update without the purpose of

[0109] Referring to FIG. 11, in some embodiments, detection device 305 performs procedure 1100 instead of procedure 900 to estimate the concentration of fluorine in mixed gas 150. Procedure 1100 is similar to procedure 900 and includes receiving (905) a portion of a fluorine-containing gas mixture 150 from the gas discharge chamber 110 and chemically reacting the fluorine and hydroxide 145 in the gas mixture 150. forming a new gas mixture 155 containing water and oxygen (910). Procedure 1100 determines whether the concentration of fluorine in new gas mixture 155 is below a lower limit (1112). For example, a fluorine sensor 360 fluidly connected to the reaction cavity 140 may make this determination (1112), and the controller 330 may determine if the concentration of fluorine in the new gas mixture 155 falls below a lower limit (1112). Only then can the step (915) of instructing the sensing device 116 to sense both the concentration of water and the concentration of oxygen (by sensors 115 and 117, respectively) in the new gas mixture 155 be proceeded. As previously discussed, the concentration of fluorine in the gas mixture 150 is estimated (920) based on the sensed concentration of oxygen.

[0110] In some embodiments, the lower limit is a value determined based on a damage threshold of sensor 115. In other embodiments, the lower limit is a value determined based on the error threshold of sensor 115. For example, the lower limit may be 0.1 ppm.

[0111] Other aspects of the invention are described in the numbered sections below.
1. receiving at least a portion of the fluorine-containing gas mixture from the gas discharge chamber;
reacting fluorine in a portion of the gas mixture with hydroxide to form a new gas mixture comprising oxygen and water;
A method comprising: sensing a concentration of water in a new gas mixture; and estimating a concentration of fluorine in a portion of the gas mixture based on the sensed concentration of water.
2. The method of clause 1, wherein the hydroxide comprises an alkaline earth metal hydroxide.
3. The method of clause 1, wherein the hydroxide is free of alkali metals and carbon.
4. The method of clause 1, wherein the gas mixture is an excimer laser gas comprising at least a mixture of a gain medium and a buffer gas.
5. adjusting the relative concentration of fluorine in the gas mixture from the gas supply set based on the estimated concentration of fluorine in the portion of the gas mixture; and adding the adjusted gas mixture from the gas supply to the gas discharge chamber. The method of clause 1 further comprising performing gas renewal by.
6. The method of clause 5, wherein performing the gas update includes filling the gas discharge chamber with a mixture of a gain medium, a buffer gas, and fluorine.
7. 7. The method of clause 6, wherein filling the gas discharge chamber with a mixture of a gain medium and a buffer gas comprises filling the gas discharge chamber with a gain medium comprising a noble gas and a halogen and a buffer gas comprising an inert gas.
8. The method of clause 7, wherein the noble gas includes argon, krypton, or xenon, the halogen includes fluorine, and the inert gas includes helium or neon.
9. filling the gas discharge chamber with a mixture of a gain medium, a buffer gas and fluorine;
adding a mixture of a gain medium, a buffer gas, and fluorine to an existing gas mixture in the gas discharge chamber, or replacing an existing gas mixture in the gas discharge chamber with a mixture of at least a gain medium, a buffer gas, and fluorine; The method of clause 6, including:
10. The method of clause 5, wherein performing the gas update includes performing one or more of a gas refill scheme or a gas injection scheme.
11. Receiving at least a portion of the gas mixture from the gas discharge chamber includes receiving a portion of the gas mixture before performing a gas update to the gas discharge chamber, wherein the gas update includes receiving at least a portion of the gas mixture from the gas supply set. The method of clause 1, comprising adding a gas mixture to the discharge chamber, the gas mixture comprising at least some fluorine.
12. 12. The method of clause 11, wherein performing the gas update includes performing one or more of a gas refill scheme or a gas injection scheme.
13. Clause 1, wherein receiving at least a portion of the gas mixture from the gas discharge chamber comprises withdrawing the gas mixture from the gas discharge chamber and directing the withdrawn gas mixture to a reaction vessel containing hydroxide. the method of.
14. further comprising transferring the new gas mixture from the reaction vessel to the measurement vessel, and sensing the concentration of water in the new gas mixture comprising sensing the concentration of water in the new gas mixture in the measurement vessel; Article 13 method.
15. 14. The method of clause 13, wherein sensing the concentration of water in the new gas mixture includes exposing a sensor in the measurement container to the new gas mixture.
16. The method of clause 1 further comprising discharging fresh gas mixture from the measurement vessel after estimating the concentration of fluorine in the portion of the gas mixture.
17. The method of clause 1, wherein sensing the concentration of water in the new gas mixture comprises sensing the concentration of water in the new gas mixture without diluting a portion of the gas mixture with another material.
18. The method of clause 1, wherein reacting a portion of the gas mixture with a hydroxide to form a new gas mixture comprising water comprises forming an inorganic fluoride compound and water.
19. 19. The method of clause 18, wherein the hydroxide comprises calcium hydroxide and the inorganic fluoride compound comprises calcium fluoride.
20. The method of clause 1, wherein sensing the concentration of water in the new gas mixture comprises sensing the concentration of water in the new gas mixture only after a predetermined period of time after initiation of the reaction.
21. Clause 1, where part of the gas mixture is exhaust gas and reacting the part of the gas mixture with hydroxide to form a new gas mixture containing water involves removing fluorine from the exhaust gas. Method.
22. Estimating the concentration of fluorine in a portion of the gas mixture based on the concentration of the detected water is based only on the concentration of the detected water and the chemical reaction between fluorine and hydroxide in the portion of the gas mixture. The method of clause 1, including estimating.
23. The method of clause 1, wherein the concentration of fluorine in the portion of the gas mixture is about 500 to 2000 ppm.
24. The method of clause 1, wherein the reaction between fluorine and hydroxide in a portion of the gas mixture to form a new gas mixture containing water is stable.
25. The reaction of fluorine in a portion of the gas mixture with hydroxide to form a new gas mixture containing water is linear and the concentration of fluorine in a portion of the gas mixture and water in the new gas mixture The method of clause 1 comprising carrying out a reaction that has a direct correlation between the concentration of.
26. The method of clause 1, further comprising sensing the concentration of oxygen in the new gas mixture, and estimating the concentration of fluorine in the portion of the gas mixture is also based on the sensed concentration of oxygen.
27. performing a first gas update by adding a first gas mixture from the gas supply set to the gas discharge chamber;
removing at least a portion of the fluorine-containing gas mixture from the gas discharge chamber after the first gas update;
reacting some fluorine of the extracted gas mixture with reactants to form a new gas mixture comprising oxygen and water;
detecting the concentration of water in a new gas mixture;
estimating the concentration of fluorine in the portion of the extracted gas mixture based on the detected concentration of water;
adjusting the relative concentration of fluorine in the second gas mixture from the gas supply set based on the estimated concentration of fluorine in the portion of the withdrawn gas mixture; and A method comprising performing a second gas update by adding gas from a supply to a gas discharge chamber.
28. 28. The method of clause 27, wherein the reactant comprises a hydroxide.
29. 28. The method of clause 27, wherein the gas mixture in the gas discharge chamber includes an excimer laser gas that includes at least a mixture of a gain medium and a buffer gas.
30. It is possible to estimate the concentration of fluorine in a portion of the mixed gas taken out based on the detected concentration of water, without measuring the fluorine concentration in the part of the mixed gas taken out. The method of clause 27, comprising estimating the fluorine concentration in the liquid.
31. An apparatus comprising: a sensing device fluidly connected to each gas discharge chamber of an excimer gas discharge system; and a control system connected to the sensing device, each sensing device comprising:
a vessel for defining a reaction cavity containing hydroxide and fluidly connected to a gas discharge chamber, for receiving a fluorine-containing gas mixture from the gas discharge chamber into the reaction cavity; a container that makes it possible to form a new gas mixture containing oxygen and water by reaction with hydroxide;
a water sensor fluidly connected to the new gas mixture and configured to sense an amount of water in the new gas mixture when fluidly connected to the new gas mixture;
The control system
receiving the output from the water sensor and estimating the concentration of fluorine in the gas mixture received from the gas discharge chamber;
determining whether to adjust the concentration of fluorine in the gas mixture from the gas supply system of the gas maintenance system based on the estimated concentration of fluorine in the gas mixture;
Sending a signal to the gas maintenance system during a gas update to the gas discharge chamber instructing the gas maintenance system to adjust the relative concentration of fluorine in the gas mixture supplied to the gas discharge chamber from the gas supply system of the gas maintenance system. A device configured to:
32. 32. The apparatus of clause 31, wherein each gas discharge chamber of the excimer gas discharge system houses an energy source and contains a gas mixture comprising a gain medium and a fluorine-containing excimer laser gas.
33. The detection device further includes a measurement vessel fluidly connected to the reaction cavity of the reaction vessel and defining a measurement cavity configured to receive the fresh gas mixture;
32. The apparatus of clause 31, wherein the water sensor is configured to detect the amount of water in the fresh gas mixture within the measurement cavity.
34. 32. The apparatus of clause 31, wherein the concentration of fluorine in the portion of the extracted gas mixture is about 500 to 2000 ppm.
35. The excimer gas discharge system includes a plurality of gas discharge chambers, a detection device is fluidly connected to each gas discharge chamber of the plurality of gas discharge chambers, and the detection device includes a plurality of vessels, each vessel containing hydroxide. defining a reaction vessel with each vessel fluidly connected to one of the gas discharge chambers, and a sensing device including a plurality of water sensors each associated with one vessel. Clause 31 device.
36. The excimer gas discharge system includes a plurality of gas discharge chambers, a detection device is fluidly connected to each gas discharge chamber of the plurality of gas discharge chambers, and the detection device includes a plurality of vessels, each vessel containing hydroxide. 32. The apparatus of clause 31, wherein each vessel is fluidly connected to one of the gas discharge chambers, and the sensing device includes a single water sensor fluidly connected to all of the vessels.

[0112] Other embodiments are within the scope of the following claims.

Claims (21)

receiving at least a portion of the fluorine-containing gas mixture from the gas discharge chamber;
reacting the fluorine in a portion of the gas mixture with a metal hydroxide to form a new gas mixture comprising oxygen and water;
A method comprising: sensing a concentration of water in the new gas mixture; and estimating a concentration of fluorine in a portion of the gas mixture based on the sensed concentration of water. 2. The method of claim 1, wherein the hydroxide comprises an alkaline earth metal hydroxide. 2. The method of claim 1, wherein the hydroxide is free of alkali metals and carbon. 2. The method of claim 1, wherein the gas mixture is an excimer laser gas including at least a mixture of a gain medium and a buffer gas. adjusting a relative concentration of fluorine in a gas mixture from a gas supply set based on the estimated concentration of fluorine in a portion of the gas mixture; and adjusting the adjusted gas mixture from the gas supply set to the 2. The method of claim 1, further comprising performing gas renewal by adding gas to the discharge chamber. 6. The method of claim 5, wherein performing the gas update includes filling the gas discharge chamber with a mixture of a fluorine-containing gain medium and a buffer gas. 5. Filling the gas discharge chamber with the mixture of the gain medium and the buffer gas comprises filling the gas discharge chamber with a gain medium comprising a noble gas and a halogen and a buffer gas comprising an inert gas. Method of Section 6. Receiving at least a portion of the gas mixture from the gas discharge chamber includes receiving a portion of the gas mixture before a gas update to the gas discharge chamber is performed, and the gas update includes gas 2. The method of claim 1, comprising adding a gas mixture to the gas discharge chamber from a supply set, the gas mixture comprising at least some fluorine. Receiving at least a portion of the gas mixture from the gas discharge chamber extracts the gas mixture from the gas discharge chamber and directs the extracted gas mixture to a reaction vessel containing the hydroxide. 2. The method of claim 1, comprising: further comprising transferring the new gas mixture from the reaction vessel to a measurement vessel, and sensing the concentration of water in the new gas mixture detecting the concentration of water in the new gas mixture in the measurement vessel. 10. The method of claim 9, comprising: 2. The method of claim 1, wherein sensing the concentration of water in the new gas mixture includes sensing the concentration of water in the new gas mixture without diluting a portion of the gas mixture with another material. Method. reacting a portion of the gas mixture with the hydroxide to form the new gas mixture comprising water; reacting a portion of the gas mixture with calcium hydroxide to form calcium fluoride and water; 2. The method of claim 1, comprising: Reacting the fluorine in a portion of the gas mixture with the hydroxide to form the new gas mixture containing water is linear and with the concentration of fluorine in the portion of the gas mixture. 2. The method of claim 1, comprising performing a reaction that has a direct correlation with the concentration of water in the new gas mixture. 2. The method of claim 1, further comprising sensing a concentration of oxygen in the new gas mixture, wherein estimating the concentration of fluorine in the portion of the gas mixture is also based on the sensed concentration of oxygen. the method of. performing a first gas update by adding a first gas mixture from the gas supply set to the gas discharge chamber;
removing at least a portion of the fluorine-containing gas mixture from the gas discharge chamber after the first gas update;
reacting a portion of the fluorine of the removed gas mixture with a reactant to form a new gas mixture comprising oxygen and water;
sensing the concentration of water in the new gas mixture;
estimating the concentration of fluorine in the extracted portion of the mixed gas based on the detected concentration of the water;
adjusting a relative concentration of fluorine in a second gas mixture from the gas supply set based on the estimated concentration of fluorine in a portion of the removed gas mixture; and A method comprising performing a second gas update by adding a gas mixture from the gas supply to the gas discharge chamber. 16. The method of claim 15, wherein the reactant comprises a metal hydroxide. 16. The method of claim 15, wherein the gas mixture in the gas discharge chamber includes an excimer laser gas including at least a mixture of a gain medium and a buffer gas. Estimating the concentration of fluorine in a portion of the extracted mixed gas based on the detected concentration of the water may be used to estimate the fluorine concentration in the extracted portion of the mixed gas without measuring the fluorine concentration in the extracted portion of the mixed gas. 16. The method of claim 15, comprising estimating the fluorine concentration in a portion of the gas mixture. An apparatus comprising a sensing device fluidly connected to each gas discharge chamber of an excimer gas discharge system and a control system connected to the sensing device, each sensing device comprising:
a vessel defining a reaction cavity containing a metal hydroxide and fluidly connected to the gas discharge chamber, the vessel for receiving a fluorine-containing gas mixture from the gas discharge chamber into the reaction cavity; a container for forming a new gas mixture comprising oxygen and water by reaction of the fluorine of the mixed gas with the hydroxide;
a water sensor fluidly connected to the new gas mixture and configured to sense an amount of water in the new gas mixture when fluidly connected to the new gas mixture;
The control system includes:
receiving an output from the water sensor and estimating a concentration of fluorine in the gas mixture received from the gas discharge chamber;
determining whether to adjust the concentration of fluorine in a gas mixture from a gas supply system of a gas maintenance system based on the estimated concentration of fluorine in the gas mixture;
a signal commanding the gas maintenance system to adjust the relative concentration of fluorine in a gas mixture supplied to the gas discharge chamber from the gas supply system of the gas maintenance system during a gas update to the gas discharge chamber; A device configured to transmit to said gas maintenance system. the detection device further includes a measurement vessel fluidly connected to the reaction cavity of the reaction vessel and defining a measurement cavity configured to receive the fresh gas mixture;
20. The apparatus of claim 19, wherein the water sensor is configured to sense the amount of water in the fresh gas mixture within the measurement cavity. The excimer gas discharge system includes a plurality of gas discharge chambers, the detection device is fluidly connected to each gas discharge chamber of the plurality of gas discharge chambers, and the detection device includes a plurality of vessels, each vessel containing the hydroxide. defining a reaction cavity containing a substance, each vessel fluidly connected to one of the gas discharge chambers, and the detection device including a single water sensor fluidly connected to all of the vessels; 20. The apparatus of claim 19.

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