JP2022545182A - Fluorine detection in gas discharge light sources - Google Patents

Abstract

The 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 hydroxide to form a new gas mixture comprising 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. [Selection drawing] Fig. 4

Description

Cross-reference to related applications
[0001] This application claims priority to U.S. Application Serial No. 62/893,377, entitled FLUORINE DETECTION IN A GAS DISCHARGE LIGHT SOURCE, filed Aug. 29, 2019, 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 gas mixtures.

[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 reactive gases, such as fluorine or chlorine. The name excimer light source derives from quasi-molecules called excimers which, under suitable conditions of electrical stimulation (energy supplied) and high pressure (of the gas mixture) exist only in an excited state and generate amplified light in the ultraviolet range. derived from the fact that it is produced

[0004] Excimer light sources produce light beams having wavelengths in the deep ultraviolet (DUV) range, which are used to pattern semiconductor substrates (or wafers) in photolithography equipment. An excimer light source can be constructed using a single gas discharge chamber or using multiple gas discharge chambers.

[0005] In some general aspects, a method comprises: receiving at least a portion of a gas mixture comprising fluorine from a gas discharge chamber; reacting the fluorine in the portion of the gas mixture with 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 mixed gas based on the sensed concentration of water. include.

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

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

[0008] A method includes adjusting the 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; It may also include performing a gas update by adding to the gas 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 gain medium and buffer gas by filling the gas discharge chamber with a gain medium containing a noble gas and a halogen and a buffer gas containing 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 adds a mixture of gain medium, buffer gas and fluorine to an existing gas mixture in the gas discharge chamber, or mixes an existing gas mixture in the gas discharge chamber with at least a mixture of gain medium, buffer gas and fluorine. can be filled with a mixture of gain medium, buffer gas and fluorine. A gas update may be performed by executing 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 renewal may include adding a gas mixture containing at least some fluorine from the gas supply set to the gas discharge chamber.

[0010] A gas update 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 the hydroxide. There is The method can 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 determines the concentration of water in the new gas mixture in the measurement vessel. including detecting The concentration of water in the new gas mixture may be sensed by exposing a sensor within the measurement vessel 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 detecting the concentration of water in the new gas mixture without diluting a portion of the mixed gas with another material.

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

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

[0016] A portion of the gas mixture may be exhaust gas, and a portion of the gas mixture reacts with the 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 the portion of the mixed gas is estimated by making an estimate based solely on the concentration of 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 a portion of the mixed gas can be about 500-2000 ppm (parts per million).

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

[0020] The fluorine in the portion of the mixed gas reacts with the hydroxide to provide a linear and direct relationship between the concentration of fluorine in the portion of the mixed gas and the concentration of water in the new gas mixture. By performing correlated reactions, new gas mixtures containing water may be formed.

[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 additionally depends on the sensed concentration of oxygen. may be based on.

[0022] In another general aspect, a method comprises: performing a first gas renewal by adding a first gas mixture from a gas supply set to a gas discharge chamber; after the first gas renewal; removing at least a portion of a fluorine-containing gas mixture from the gas discharge chamber; reacting the fluorine in a portion of the removed gas mixture with reactants to form a new gas mixture comprising oxygen and water; estimating the concentration of fluorine in the portion of the mixed gas withdrawn based on the concentration of water detected; a second gas renewal by adjusting the relative concentration of fluorine in a second gas mixture from the gas supply set and adding the adjusted second gas mixture from the gas supply to the gas discharge chamber based on including running

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

[0024] The fluorine concentration in the part of the mixed gas taken out can be obtained by estimating the fluorine concentration in the part of the taken out mixed gas without measuring the fluorine concentration in the part of the taken out mixed gas. , 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 an excimer gas discharge system, and a control system connected to the detection device. Each detection device defines a reaction cavity containing a hydroxide and fluidly connected to a gas discharge chamber, a vessel for receiving into the reaction cavity a mixed gas containing fluorine from the gas discharge chamber, a water sensor; including. The vessel allows the reaction of fluorine and hydroxide of the received mixed gas to form a new gas mixture containing oxygen and water. A water sensor is fluidly connected to the new gas mixture and configured to sense the amount of water in the new gas mixture when fluidly connected to the new gas mixture. A 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 based on the estimated concentration of fluorine in the gas mixture, the gas supply system of the gas maintenance system. determining whether to adjust the concentration of fluorine in the gas mixture from the gas supply system of the gas maintenance system to the gas discharge chamber during a gas update to the gas discharge chamber; It is configured to send a signal to the gas maintenance system that commands the gas maintenance system to adjust the concentration.

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

[0027] The detection apparatus 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 new gas mixture. A water sensor may be configured to sense the amount of water in the new gas mixture within the measurement cavity.

[0028] The concentration of fluorine in the portion of the withdrawn mixed gas 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 the hydroxide, each vessel fluidly connected to one of the gas discharge chambers, the detection device each It includes multiple water sensors associated with one container. The detection device may include a plurality of vessels, each vessel defining a reaction cavity containing the hydroxide, each vessel fluidly connected to one of the gas discharge chambers, the detection device comprising: Includes 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] Figure 2 is a block diagram of the apparatus of Figure 1 embodied as part of a deep ultraviolet (DUV) light source that produces a beam of light that is directed into a photolithographic apparatus; [0032] FIG. 2 is a block diagram of one embodiment of the detection device of the apparatus of FIG. 1, wherein the detection device comprises a fluorine sensor; [0033] Figure 2 is a block diagram of an embodiment of the apparatus of Figure 1, wherein the detection device includes a buffer vessel; [0034] FIG. 2 is a block diagram of an embodiment of the apparatus of FIG. 1, wherein the detection device includes multiple reaction vessels, each reaction vessel being associated with one of the multiple chambers. [0035] Figure 3 is a block diagram of an embodiment of the apparatus of Figure 2, showing details of an exemplary DUV light source; [0036] Figure 7 is a block diagram of one embodiment of a control system that is part of the DUV light source shown in Figure 2 or Figure 6; [0037] Figure 2 is a block diagram of another embodiment of the apparatus of Figure 1, wherein the apparatus is implemented in conjunction with a fluorine scrubber; [0038] Fig. 4 is a flow chart of the procedure performed by the detection device to detect the concentration of fluorine in the gas mixture of the chamber; [0039] FIG. 10 is a flow chart of the procedure performed by the device once the fluorine concentration has been estimated and the procedure of FIG. 9 has been completed; [0040] FIG. 10 is a flow chart of a procedure performed by the detection device in place of the procedure of FIG. 9 for estimating the concentration of fluorine in the gas mixture in the chamber;

[0041] Referring to FIG. 1, apparatus 100 measures the concentration of fluorine (F) in gas mixture 107 in chamber 110 without directly measuring the concentration of fluorine (F) in gas mixture 107 in chamber 110 using a commercially available fluorine sensor. includes a sensing device 105 configured to measure or estimate the . 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 molecular fluorine _F2 . _The concentration of molecular fluorine F2 in chamber 110 is in a range too high to allow direct detection of fluorine. For example, the concentration of fluorine in 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 a commercially available fluorine sensor. Instead, detector 105 enables a chemical reaction that converts fluorine from chamber 110 into one or more components (including water) that can each be detected and measured by commercially available sensors 115 of detector 116 . Based on the amount of water present after the chemical reaction (provided by sensor 115), and based on information about the chemical reaction, detector 105 determines how much fluorine was present before the start of the chemical reaction. can be calculated or estimated.

[0042] In order to make this estimation accurate, the detection device 105 assumes 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 water concentration at time. Alternatively, the detection device 105 can assume that the conversion of fluorine is complete ₍ so there is no residual molecular fluorine F2 in the gas after the chemical reaction).

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

[0044] The apparatus 100 includes a controller 130 that receives the output from the water sensor 115 and estimates the amount of fluorine in the gas mixture 107 by calculating how much fluorine was present before the start of the chemical reaction. . Controller 130 uses this information to determine if the concentration of fluorine in gas mixture 107 needs to be adjusted. Accordingly, controller 130 determines how to adjust the relative amounts of gas in the supplies of gas maintenance system 120 that are to be transferred into and out of chamber 110 based on this determination. Controller 130 sends signals to gas maintenance system 120 commanding it to adjust the relative concentration of fluorine in gas mixture 107 during a gas update to chamber 110 .

[0045] The detection device 105 includes a reaction vessel 135 defining a reaction cavity 140 containing a hydroxide Σ(-OH) 145 (where Σ is a metal). Reaction cavity 140 is fluidly connected to chamber 110 via conduit 137 to receive 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 mixed gas 150 into reaction cavity 140 and to direct mixed gas 150 into reaction vessel 135 . can control the flow rate of Reaction cavity 140 thus allows the 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 should be made of non-reactive materials so as not to interfere with or alter the chemical reaction between fluorine and hydroxide 145 in the received gas mixture 150. not. For example, the interior of reaction vessel 135 can be made of a non-reactive metal such as stainless steel or monel metal.

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

[0047] The water sensor 115 (and optionally the oxygen sensor 117) may be inside the measurement cavity 175 of the measurement vessel 170. As shown in FIG. 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 introducing fresh gas mixture 155 into measurement cavity 175 and to into the measurement vessel 170 can be controlled.

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

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

[0050] An example of an oxygen sensor 117 suitable for this concentration range is an oxygen analyzer that uses a precision zirconia oxide sensor for oxygen detection. Zirconia oxide sensors include cells made from high purity, high density, stabilized zirconia ceramic. A zirconia oxide sensor produces a voltage signal indicative of the oxygen concentration of the new gas mixture 155 . The zirconia sensor output is also analyzed (eg, converted and linearized) by a high-speed microprocessor within oxygen sensor 117 to provide a direct digital readout for use by controller 130 . A conventional zirconium oxide cell includes a zirconium oxide ceramic tube plated with porous platinum electrodes on its inner and outer surfaces. A zirconia oxide sensor becomes an oxygen ion conducting electrolyte when heated above a certain temperature (eg, 600C or 1112 degrees Fahrenheit). The electrodes provide a catalytic surface for the conversion of molecular oxygen _O2 to oxygen ions and oxygen ions to molecular oxygen. Oxygen molecules on the rich reference gas side of the cell acquire electrons that become ions that penetrate 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 zirconia oxide sensor, oxygen ions migrate 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 for reacting the fluorine in the mixed gas 150 with the hydroxide 145 is that the chemical reaction between fluorine and hydroxide is a stoichiometrically simple chemical reaction that is easily performed and controlled. be. Moreover, the controlled stoichiometry of this chemical reaction is fixed. Also, the chemical reaction between fluorine and hydroxide is a stable chemical reaction. A chemical reaction is not reversible and may be stable if 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 gas mixture 150 that is stable and has a controlled stoichiometry is now considered.

[0052] In some examples, the hydroxide 145 is in the form of a particulate solid powder. Additionally, the hydroxide 145 in particulate form can be tightly packed within the reaction vessel 135 (which may be a tube) such that the particles in the hydroxide 145 powder do not migrate. The area or volume of space within the reaction vessel 135 outside the hydroxide 145 powder is considered a pore, and by using the hydroxide 145 in granular form, complete chemical reaction between the hydroxide 145 and fluorine can be achieved. It is possible to ensure that there is a large surface area to allow. 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 may fill the reaction cavity 140 within the reaction vessel 135 . The shape of the reaction vessel 135 and thus the reaction cavity 140 is not limited to any particular form.

[0054] Hydroxide 145 includes metal Σ, which may be an alkaline earth metal. Further, hydroxide 145 is free of alkali metals and carbon. Hydroxide 145 may therefore be calcium hydroxide [Ca(OH) ₂ ] (where Σ is Ca in this example). Calcium hydroxide is in a granular solid form and has 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 and allow chemical reaction. For example, calcium hydroxide can be in the form of particles that are packed into a column, with the packing level depending on the fluorine concentration level in the gas mixture 150 to be analyzed. Gas mixture 150 is passed (eg, flowed) through hydroxide 145 to allow chemical reaction between fluorine and calcium hydroxide.

[0055] In the presence of fluorine gas (F2) in the gas mixture 150, the following _two -step chemical reaction occurs when the hydroxide is calcium fluoride Ca(OH) ₂ .
1) 2F2 ₊ Ca(OH) ₂ = _CaF2 +OF2 _{+ H2O} ,
₂ ) OF2 + Ca(OH) ₂ = _CaF2 + _O2 + _H2O .
For every _two fluorine molecules (F2) interacting with a molecule of calcium hydroxide [Ca(OH) ₂ ] 145, two inorganic fluoride compound (calcium fluoride or _CaF2 ) molecules and one oxygen A molecule (O ₂ ) and two water molecules (H ₂ O) are produced. This chemical reaction is linear and stoichiometrically simple. Thus, looking only at fluorine and water, _one water molecule _H2O is produced from the chemical reaction for every one fluorine molecule F2 input into the chemical reaction. Another way of stating this is that for every mole of fluorine F2 put into the chemical reaction, _one mole of _H2O is produced from the chemical reaction. Thus, if ₂ moles of fluorine F2 are put into a chemical reaction, 2 moles of water _H2O are released after the chemical reaction. This water is detected by water sensor 115 . Thus, for example, controller 130 knows (from access to data in stored memory) that the ratio of fluorine to water in this chemical reaction is 1:1, so sensor 115 detects 0.6 mol. of water is detected, controller 130 determines that 0.6 moles of fluorine was present in gas mixture 107 . In another embodiment, the detection device 105 can assume that the conversion of fluorine is complete (so there _are no residual fluorine molecules F2 in the gas after the chemical reaction). For example, this assumption can be a valid one if enough time has passed since the start of the chemical reaction.

[0056] In this example, if the sensing device 116 also includes an oxygen sensor 117, the oxygen concentration measurement from the oxygen sensor 117 can be used in combination with the water measurement from the water sensor 115. Thus, if 4 moles of fluorine F2 are introduced into the chemical reaction, ₂ moles of oxygen _O2 are released after the chemical reaction. This oxygen is detected by the oxygen sensor 117 . As an example, controller 130 knows that the ratio of fluorine to oxygen in this chemical reaction is 2:1, so if 0.3 moles of oxygen is detected by sensor 117, controller It is determined that 0.6 moles of fluorine was present in the Controller 130 uses data from both oxygen sensor 117 and water sensor 115 to determine the concentration of fluorine present in gas mixture 107 (because the weight or mass of oxygen, water, and fluorine are known). can be estimated. For example, both data sets can be used to make more accurate measurements of fluorine. As will be appreciated by those skilled in the art, the controller may also employ additional calibrations and corrections (eg, to account for fluorine, oxygen, or water consumption or inefficient detection).

[0057] In some embodiments, the chemical reaction between hydroxide 145 and fluorine in mixed gas 150 occurs under one or more specially designed conditions. For example, the reaction between hydroxide 145 and fluorine in gas mixture 150 can occur in the presence of one or more catalysts that change the rate of the chemical reaction but are chemically unchanged substances at the end of the chemical reaction. have a nature. As another example, the reaction between hydroxide 145 and fluorine in mixed gas 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, for example, an ultraviolet (UV) or deep ultraviolet (DUV) light beam 211 that is directed to a photolithographic apparatus 222 for patterning microelectronic features on a wafer. It can be implemented within the light source 200 . Light source 200 includes a control system 290 connected to the various elements of light source 200 to enable generation of light beam 211 . Although control system 290 is shown as a single block, it can also be composed of multiple sub-components, any one or more of which can be removed from the other sub-components or placed within light source 200 . can be local to the elements of Further, controller 130 may be considered part of control system 290 or part of device 100 .

[0059] In this example, the apparatus 100 is configured to calculate the concentration of fluorine inside one or more of the gas discharge chambers 210 of the excimer gas discharge system 225 that produces 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 may include multiple gas discharge chambers 210, any one or more of which may be associated with the detector 105 of the apparatus 100 and the 2 are in fluid communication with other elements (such as optical elements, metrology devices, and electromechanical elements) for controlling characteristics of the light beam 211 not shown in FIG. Furthermore, only those components of light source 200 that are relevant to apparatus 100 are shown in FIG. For example, light source 200 may include a beam shaping system located at the output of final gas discharge chamber 210 to adjust one or more properties of light beam 211 directed to photolithography apparatus 222 .

Gas discharge chamber 210 houses energy source 230 and contains gas mixture 207 . Energy source 230 provides an energy source for gas mixture 207 . Specifically, energy source 230 provides sufficient energy to gas mixture 207 to induce population inversion to enable gain via stimulated emission within chamber 210 . In some examples, energy source 230 is an electrical discharge provided by a pair of electrodes positioned within gas discharge chamber 210 . In another example, 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 of the gas mixture 207 in the gas discharge chamber 210 (which provides the gain medium for light amplification) is consumed, thus reducing the amount of light amplification over time, and thus the light source 200 The characteristics of the light beam 211 produced change. The photolithographic apparatus 222 attempts to maintain the concentration of fluorine in the gas mixture 207 within the gas discharge chamber 210 within a specified tolerance with respect to the concentration of fluorine set in the initial gas refill procedure. For this reason, additional fluorine is added to the gas discharge chamber 210 periodically under control of the gas maintenance system 120 . Since fluorine consumption varies from gas discharge chamber to gas discharge chamber, a closed loop control is used to determine the amount of fluorine introduced or injected into the gas discharge chamber 210 each time. Apparatus 100 is used to determine the concentration of fluorine remaining in gas discharge chamber 210 and is therefore used throughout schemes for determining the amount of fluorine to introduce or inject into 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 quasi-molecules. Thus, pumping gas mixture 207 (and thus the gain medium) with an electrical discharge from energy source 230 causes population inversion in the gain medium via stimulated emission. As noted above, the gain medium typically includes noble gases and halogens, and the buffer gas typically includes inert gases. 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 the gas mixture 207 are inert (noble gases or noble gases), so the only chemical reaction that occurs between the gas mixture 150 and the hydroxide 145 is the fluorine of the gas mixture 150 and the water. A reaction between oxide 145 is assumed.

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

[0064] Referring to FIG. 3, in some embodiments 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 is 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, since fluorine sensor 360 has a minimum detection threshold, it can be used to detect when the concentration of fluorine in new gas mixture 155 is below a lower limit. For example, the fluorine sensor 360 may saturate at a concentration of 10 ppm, but has a minimum detection threshold of about 0.05 ppm, and the concentration of fluorine in the new gas mixture 155 drops below 0.1 ppm before the concentration of fluorine in the new gas mixture 155 falls below 0.1 ppm. Detection of fluorine in 155 can begin.

Controller 130 is configured as controller 330 that receives the output from fluorine sensor 360 . Controller 330 includes modules that interact with flow control devices 365 in lines that carry 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 allows the flow of the fresh gas mixture 155 to the oxygen sensor 117 only if it determines from the output of the fluorine sensor 360 that the concentration of fluorine in the fresh gas mixture 155 is below a lower limit (eg, 0.1 ppm). A signal is sent to the flow control device 365 to enable the In this way, the oxygen sensor 117 is exposed to the new gas mixture 155 only when the concentration of fluorine is below the lower limit, thereby protecting the oxygen sensor 117 from unacceptable levels of fluorine. The lower limit value may be a value determined based on the damage threshold of oxygen sensor 117 . Therefore, a fluorine concentration higher than the lower limit may damage the oxygen sensor 117 . The lower limit value may be a value determined based on the oxygen sensor 117 error threshold. Therefore, at fluorine concentrations higher than the lower limit, measurement errors can affect the accuracy of oxygen sensor 117 .

[0067] The detection device 305 also includes a measurement vessel 370 fluidly connected to the reaction cavity 140 of the reaction vessel 135. As shown in FIG. 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 . Measurement vessel 370 contains fresh gas mixture 155 , enabling water sensor 115 to detect the concentration of water in fresh gas mixture 155 and oxygen sensor 115 to detect the concentration of oxygen in fresh gas mixture 155 . any container that The interior of measurement vessel 370 defining measurement cavity 375 must be made of a non-reactive material so as not to change the composition of new gas mixture 155 . For example, the interior of measurement vessel 370 may be made of a non-reactive metal.

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

[0069] In one example, the concentration of fluorine in chamber 110 is about 1000 ppm, the volume of chamber 110 is 36 liters (L), and the pressure in chamber 110 is 200-400 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 water concentration of 1000 ppm, and an oxygen concentration of approximately 500 ppm. After the water sensor 115 has performed the water concentration measurement (optionally the oxygen sensor 117 has performed the oxygen concentration measurement) and output 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. In some embodiments, as shown in FIG. 5, device 100 is designed as device 500 and detection device 105 includes 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. where i is an integer greater than one. The detection device 505 includes each chamber 510_1, 510_2, . . . 510_i associated with separate or dedicated sensing devices 516_1, 516_2, . . . 516_i. Thus, each sensing device 516_1, 516_2, . . . 516_i is used for each chamber 510_1, 510_2, . . . Fluorine concentration in 510_i can be measured.

[0071] The sensing device 505 is connected to a gas maintenance system 520, which is part of the master conduit system 527, each conduit system 527_1, 527_3, . . . 527_i to each chamber 510_1, 510_2, . . . 510_i, including a gas supply system fluidly connected to 510_i. Gas maintenance system 520 includes one or more gas supplies and any gases from those supplies to each chamber 510_1, 510_2, . . . 510_i, and a control unit for controlling whether to transfer in and out of 510_i. Detector 505 detects each chamber 510_1, 510_2, . . . 510_i to each conduit 537_1, 537_2, . . . 537_i to mix gases 550_1, 550_2, . . . 550_i for each reaction vessel 535_1, 535_2, . . . 535_i. Each reaction vessel 535_1, 535_2, . . . Received gas mixture 550_1, 550_2, . . . 550_i fluorine and hydroxide 545_1, 545_2, . . . 545_i and new gas mixtures 555_1, 555_2, . . . 555_i to each sensing device 516_1, 516_2, . . . 516_i.

[0072] Detector 505 includes gas maintenance system 520 and detectors 516_1, 516_2, . . . 516_i 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 to receive the output from reaction vessels 535_1, 535_2, . . . Each gas mixture 507_1, 507_2, . . . Estimate the amount of fluorine in 507_i.

[0073] In another embodiment, all chambers 510_1, 510_2, . . . It is possible to use a single sensing device 516 that measures fluorine in 510_i. However, this is because detection device 505 detects chambers 510_1, 510_2, . . . 510_i and detection device 505, including appropriate plumbing to connect chambers 510_1, 510_2, . . . 510_i to prevent cross-talk between measurements performed by sensing device 516 on each of 510_i. Furthermore, the single detector 516 design can work because gas exchange is performed in only one chamber 510 at a time, so that the controller 530 can detect fluorine in a single chamber 510 at any one time. can be measured.

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

[0075] MO 601 provides a light beam 606 (which may be referred to as a seed light beam) to PA 602. MO gas discharge chamber 610_1 contains a gas mixture 607_1 containing a gain medium in which amplification occurs, MO 601 is connected to spectral characteristic selection system 680 on one side of MO gas discharge chamber 610_1 and on a second side of 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 of the .

[0076] The PA gas discharge chamber 610_2 contains a gas mixture 607_2 containing a gain medium 607_2 in which amplification occurs when a seed light beam 606 is seeded from the MO 601 . If 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. PA 602 includes beam return 682, which returns the light beam (eg, by reflection) into 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 at relatively low output pulse energies (compared to the output of PA 602). PA receives seed light beam 606 from MO 601 and amplifies this output to obtain the necessary power in output light beam 211 for use in an output device such as photolithography apparatus 222 . Seed light beam 606 is amplified by repeatedly passing through PA 602 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 amplified light beams (such as seed light beam 606 and output light beam 211) around the required wavelength and bandwidth. may be a combination of different gases. For example, 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] The detection device 605 includes a gas maintenance system 620, which is a gas management system for the excimer gas discharge system 625, specifically for the gas discharge chambers 610_1 and 610_2. Gas maintenance system 620 includes one or more gas sources 651 A, 651 B, 651 C, etc. (such as sealed gas containers or gas cylinders) and valve system 652 . One or more gas sources 651 A, 651 B, 651 C, etc. are connected to MO gas discharge chamber 610_1 and PA gas discharge chamber 610_2 via valve sets 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, gas mixtures 607_1, 607_2 contain various partial pressures of halogen, such as fluorine, and other gases, such as argon, neon, and possibly others, which 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 fluorine, a halogen, argon, a noble gas, and one or more other gases such as 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 called a trimix because it contains three gases. 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 because it contains two gases.

[0081] The gas maintenance system 620 may include a valve controller 653, which transfers gas from a particular gas source 651A, 651B, 651C, etc. into the gas discharge chambers 610_1, 610_2 to the valve system 652 in gas renewal. configured to send one or more signals to the valve system 652 to cause the valve system 652 to The gas renewal can be a refill of the gas mixture 607 in the gas discharge chamber, replacing the existing gas mixture in the gas discharge chamber with at least a mixture of gain medium, 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 to cause valve system 652 to bleed gas from discharge chambers 610_1, 610_2 when necessary. , such extracted gas may be discharged to a gas dump represented at 689 . Alternatively, in some embodiments, the withdrawn gas may be supplied 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 light amplification) within the gas discharge chambers 610_1, 610_2 is consumed, thus reducing light amplification over time. , and thus the energy of the light beam 211 used by the photolithographic apparatus 222 for wafer processing. Additionally, during operation of the DUV light source 600, contaminants can 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 of the gas sources 651A, 651B, 651C, etc. to flush out contaminants or replenish lost fluorine.

[0084] The reason that 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, using a halogen-free gas in gas source 651B. may be

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

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

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

[0088] Referring to FIG. 7, a block diagram illustrates 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). Details are provided regarding the control system 790 in relation to aspects of the detector 105/605 and the methods for gas control and fluorine concentration estimation described herein. Additionally, control system 790 may include other features not shown in FIG. Control system 790 generally includes one or more of digital electronics, 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; 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 keyboards, touch screens, microphones, mice, handheld input devices, 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 executed by a programmable processor (such as processor 715). . One or more programmable processors 715 may each execute a program of instructions to perform desired functions by operating on input data and generating appropriate output. In general, processor 715 receives instructions and data from memory 700 . Any of the foregoing may be supplemented by or incorporated in specially designed ASICs (Application Specific Integrated Circuits).

[0091] Control system 790 also includes, among other components or modules, controllers 130, 330, 530 of sensing device 105 (represented by box 730 in FIG. 7) and valve controller 653 of gas maintenance system 620. 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, any of the controllers/modules 730 , 731 can access data stored within memory 700 .

[0092] Connections between controllers/features/modules in control system 790 and between controllers/features/modules in control system 790 and other components of apparatus 100 (which may be DUV light source 600). Connections between may be wired or wireless.

[0093] Although only a few modules are shown in FIG. 7, control system 790 may include other modules as well. Further, although the control system 790 is represented as a box with all components appearing to be co-located, the control system 790 can also consist of components that are physically separated from each other in space or time. 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 separate from other components of control system 790 .

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

[0095] Referring to FIG. 8, in some embodiments, apparatus 100 is designed as apparatus 800 and detection device 105 is a detection device operating in parallel with a fluorine scrubber 804 in fluid communication with gas maintenance system 820. It is designed as device 805 . The fluorine scrubber 804 is used in conjunction with the gas maintenance system 820 to chemically react the fluorine in the gas mixture 807 to form chemicals that can be safely disposed of, for example, through the exhaust, thereby cleaning the chamber 110 . properly exhaust the gas mixture 807 from.

A portion of the mixed gas 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 . Fluorine in the gas mixture 150 chemically reacts (as discussed above) with the hydroxide 845 in the fluorine scrubber 835 and is converted to a new gas mixture 155 containing oxygen. The new gas mixture 155 is directed to the detector 116 where it is detected. Controller 130 estimates the concentrations of oxygen and fluorine in gas mixture 150 and gas mixture 107 and determines how gas maintenance system 820 should be adjusted to perform gas renewal. In this example, gas maintenance system 820 includes 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 control 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. As shown in FIG. Although referring to the apparatus of Figure 1, the procedure 900 also applies to the apparatus described with reference to Figures 2-8. Detector 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 new gas mixture 155 including water (910). The water concentration in the new gas mixture 155 is sensed 915 , for example by water sensor 115 . Also, based on the detected concentration of water, the concentration of fluorine in the mixed gas 150 is estimated (920). For example, controller 130 may estimate the concentration of fluorine in gas mixture 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 can receive the gas mixture 150 (905). For example, gas maintenance system 120 may include valves that allow gas mixture 107 to be withdrawn from chamber 110 and then directed to detector 105 as mixed gas 150 . The pressure in 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, to push gas mixture 107 from chamber 110 to detector 105. push out to The amount of mixed gas 150 required in reaction vessel 135 may be determined based on the need for water sensor 115 to provide accurate and stable readings. The limiting factor on the amount of mixed gas 150 is the fluorine conversion capacity of hydroxide 145 in 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 that is exhausted from the chamber 110 to the fluorine scrubber, and thus the gas mixture 150 may be considered an exhaust gas. . Such an example 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 containing 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 from gas maintenance system 120 to chamber 110, 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 from gas maintenance system 120 to chamber 110 . The concentration of fluorine (or amount of fluorine) in the adjusted second gas mixture may be based on measurements made by procedure 900 .

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

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

[0103] Further, the sensing (915) of the concentration of water in the new gas mixture 155 may wait until, or only after, a predetermined time after initiation of the chemical reaction (910). 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 amount of fluorine and total amount of hydroxide 145 in the gas mixture 150, it may take seconds or minutes to completely convert the fluorine to water.

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

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

[0106] Upon completion of procedure 900 (i.e., after estimating 920 the concentration of fluorine in gas mixture 150), new gas mixture 155 is drained (removed) from measurement vessel 170 to produce a new batch of gas mixture 150. It is possible to perform the 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. FIG. The gas maintenance system 120 receives output from the controller 130 of the detector 105 and, based on the estimated fluorine concentration, determines the relative concentration of fluorine in the gas mixture from the gas supply sets (gas sources 651A, 651B, 651C, etc.). Adjust the density (1005). Gas maintenance system 120 performs a gas refresh by adding a conditioned gas mixture to chamber 110 via conduit system 127 until the pressure within chamber 110 reaches a desired 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 the gas discharge chamber 210 with a mixture of gain medium, buffer gas, and fluorine. The gain medium contains a noble gas and fluorine and the buffer gas contains an inert gas. It is possible to delay performing the gas update (1010) relative to when the fluorine concentration estimation (900) is performed. In some examples, if the controller 130 determines that the concentration of fluorine in the gas mixture 107 has fallen below an acceptable level, the estimation (900) can be immediately followed by an adjustment (1005) and a gas update (1010). can. In some embodiments, fluorine adjustment (1005) can be delayed until it is determined that the concentration of fluorine in gas mixture 107 has fallen below an acceptable level. For example, if controller 130 determines that the concentration of fluorine in gas mixture 107 is still high, but 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 gas mixture 150. FIG. Procedure 1100 is similar to procedure 900 and includes the steps of receiving (905) a portion of fluorine-containing gas mixture 150 from gas discharge chamber 110 and chemically reacting fluorine and hydroxide 145 in gas mixture 150. and allowing 910 to form a new gas mixture 155 comprising water and oxygen. Procedure 1100 determines (1112) whether the concentration of fluorine in new gas mixture 155 is below a lower limit. For example, the fluorine sensor 360 fluidly connected to the reaction cavity 140 may make this determination (1112), and the controller 330 detects when the concentration of fluorine in the new gas mixture 155 is below the lower limit (1112). Only then can one proceed to step 915 of instructing sensing device 116 to sense both the concentration of water and the concentration of oxygen in new gas mixture 155 (by sensors 115 and 117, respectively). As previously described, the concentration of fluorine in the gas mixture 150 is estimated 920 based on the sensed concentration of oxygen.

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

[0111] Other aspects of the invention are described in the following numbered sections.
1. receiving at least a portion of the fluorine-containing gas mixture from the gas discharge chamber;
reacting fluorine in a portion of the mixed gas with hydroxide to form a new gas mixture comprising oxygen and water;
A method comprising: sensing the concentration of water in a new gas mixture; and estimating the concentration of fluorine in a portion of the mixed gas 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. 2. The method of clause 1, wherein the gas mixture is an excimer laser gas comprising a mixture of at least 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 a gas update by.
6. 6. The method of clause 5, wherein performing a gas update comprises filling the gas discharge chamber with a mixture of gain medium, buffer gas and fluorine.
7. 7. The method of clause 6, wherein filling the gas discharge chamber with a mixture of gain medium and 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. 8. The method of clause 7, wherein the noble gas comprises argon, krypton or xenon, the halogen comprises fluorine and the inert gas comprises helium or neon.
9. filling the gas discharge chamber with a mixture of gain medium, buffer gas and fluorine
adding the mixture of gain medium, buffer gas and fluorine to the existing gas mixture in the gas discharge chamber, or replacing the existing gas mixture in the gas discharge chamber with at least the mixture of gain medium, buffer gas and fluorine. The method of Clause 6, including
10. 6. The method of clause 5, wherein performing a gas update comprises performing one or more of a gas refilling 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 a gas update to the gas discharge chamber is performed, wherein the gas update is performed from the gas supply set. 2. 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 a gas update comprises 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 mixed gas from the gas discharge chamber comprises withdrawing the mixed gas from the gas discharge chamber and directing the withdrawn mixed gas to a reaction vessel containing the hydroxide. the method of.
14. further comprising transferring the new gas mixture from the reaction vessel to the measurement vessel, wherein sensing the concentration of water in the new gas mixture comprises sensing the concentration of water in the new gas mixture in the measurement vessel; Method of clause 13.
15. 14. The method of clause 13, wherein sensing the concentration of water in the new gas mixture comprises exposing a sensor in the measurement vessel to the new gas mixture.
16. The method of clause 1, further comprising venting a new 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 mixed gas with another material.
18. The method of Clause 1, wherein reacting a portion of the mixed gas with 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. 2. 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 has elapsed after initiation of the reaction.
21. of clause 1, wherein a portion of the gas mixture is exhaust gas and reacting a portion of the gas mixture with hydroxide to form a new gas mixture comprising water comprises removing fluorine from the exhaust gas Method.
22. estimating the concentration of fluorine in the portion of the gas mixture based on the sensed concentration of water based solely on the chemical reaction between fluorine and hydroxide in the portion of the gas mixture and the sensed concentration of water; The method of Clause 1, including inferring.
23. 2. The method of clause 1, wherein the concentration of fluorine in the portion of the mixed gas is from about 500 to 2000 ppm.
24. 2. The method of clause 1, wherein the reaction of fluorine and hydroxide in a portion of the mixed gas to form a new gas mixture containing water is stable.
25. The reaction of fluorine in a portion of the mixed gas with hydroxide to form a new gas mixture containing water is linear and the concentration of fluorine in the portion of the mixed gas and water in the new gas mixture is linear. The method of Clause 1, comprising performing a reaction that is directly correlated with the concentration of
26. The method of clause 1, further comprising sensing the concentration of oxygen in the new gas mixture, wherein estimating the concentration of fluorine in the portion of the mixed gas is also based on the sensed concentration of oxygen.
27. performing a first gas renewal 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 renewal;
reacting a portion of the fluorine of the withdrawn gas mixture with the reactants 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 water;
adjusting the relative concentration of fluorine in the second gas mixture from the set of gas supplies based on the estimated concentration of fluorine in the portion of the withdrawn gas mixture; A method comprising performing a second gas renewal by adding to the gas discharge chamber from a supply.
28. 28. The method of clause 27, wherein the reactants comprise hydroxides.
29. 28. The method of clause 27, wherein the gas mixture in the gas discharge chamber comprises at least an excimer laser gas comprising a mixture of gain medium and buffer gas.
30. Estimating the concentration of fluorine in the portion of the removed mixed gas based on the detected concentration of water is a method of estimating the concentration of fluorine in the portion of the removed mixed gas without measuring the fluorine concentration in the portion of the removed mixed gas. 28. The method of clause 27, comprising estimating the fluorine concentration in the part.
31. An apparatus comprising a detection device fluidly connected to each gas discharge chamber of an excimer gas discharge system and a control system connected to the detection device, each detection device comprising:
A vessel for defining a reaction cavity containing a hydroxide and fluidly connected to the gas discharge chamber, and for receiving a fluorine-containing gas mixture from the gas discharge chamber into the reaction cavity, the fluorine in the received gas mixture. a vessel allowing to form a new gas mixture comprising oxygen and water by the reaction of the hydroxide with
a water sensor fluidly connected to the new gas mixture and configured to sense the 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 delivery system of the gas maintenance system based on the estimated concentration of fluorine in the gas mixture;
During a gas update to the gas discharge chamber, a signal is sent to the gas maintenance system 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 delivery 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 contains 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 new 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 mixed gas withdrawn is from about 500 to 2000 ppm.
35. An 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, the detection device includes a plurality of vessels, each vessel containing hydroxide. defining a reaction vessel in which each vessel is fluidly connected to one of the gas discharge chambers, and a detection device including a plurality of water sensors each associated with one vessel. Clause 31 equipment.
36. An excimer gas discharge system includes a plurality of gas discharge chambers, a detection device fluidly connected to each gas discharge chamber of the plurality of gas discharge chambers, the detection device including a plurality of vessels, each vessel containing a hydroxide. 32. The apparatus of clause 31, defining reaction vessels in which each vessel is fluidly connected to one of the gas discharge chambers, and wherein the detection device comprises a single water sensor fluidly connected to all of the vessels.

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

Claims (36)

receiving at least a portion of the fluorine-containing gas mixture from the gas discharge chamber;
reacting the fluorine in a portion of the mixed gas with hydroxide to form a new gas mixture comprising oxygen and water;
A method comprising: 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. 2. The method of claim 1, wherein said hydroxide comprises an alkaline earth metal hydroxide. 2. The method of claim 1, wherein said hydroxide is free of alkali metals and carbon. 2. The method of claim 1, wherein said gas mixture is an excimer laser gas comprising a mixture of at least a gain medium and a buffer gas. adjusting the relative concentration of fluorine in a gas mixture from a set of gas supplies based on the estimated concentration of fluorine in a portion of the mixed gas; and transferring the adjusted gas mixture from the gas supply to the gas. 2. The method of claim 1, further comprising performing a gas update by adding to the discharge chamber. 6. The method of claim 5, wherein performing the gas update comprises filling the gas discharge chamber with a mixture of gain medium, buffer gas and fluorine. Filling the gas discharge chamber with a 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. Item 6 method. 8. The method of claim 7, wherein said noble gas comprises argon, krypton, or xenon, said halogen comprises fluorine, and said inert gas comprises helium or neon. filling the gas discharge chamber with a mixture of the gain medium, the buffer gas and fluorine;
adding the mixture of the gain medium, the buffer gas and fluorine to an existing gas mixture in the gas discharge chamber; or mixing the existing gas mixture in the gas discharge chamber with at least the gain medium and the buffer gas. 7. The method of claim 6, comprising exchanging for said mixture of fluorine. 6. The method of claim 5, wherein performing the gas update comprises performing one or more of a gas refill scheme or a gas injection scheme. 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, wherein the gas update 2. The method of claim 1, comprising adding a gas mixture to said gas discharge chamber from a supply set, said gas mixture comprising at least some fluorine. 12. The method of claim 11, wherein performing the gas update comprises performing one or more of a gas refill scheme or a gas injection scheme. Receiving at least a portion of the gas mixture from the gas discharge chamber withdraws the gas mixture from the gas discharge chamber and directs the withdrawn 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, wherein sensing the concentration of water in the new gas mixture senses the concentration of water in the new gas mixture in the measurement vessel. 14. The method of claim 13, comprising: 14. The method of claim 13, wherein sensing the concentration of water in the new gas mixture comprises exposing a sensor in the measurement vessel to the new gas mixture. 2. The method of claim 1, further comprising evacuating the new gas mixture from the measurement vessel after estimating the concentration of fluorine in the portion of the gas mixture. 2. The method of claim 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 mixed gas with another material. Method. 2. The method of claim 1, wherein reacting a portion of said mixed gas with said hydroxide to form said new gas mixture comprising water comprises forming an inorganic fluoride compound and water. 19. The method of claim 18, wherein said hydroxide comprises calcium hydroxide and said inorganic fluoride compound comprises calcium fluoride. 2. The method of claim 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 has elapsed after initiation of the reaction. . a portion of said mixed gas is an exhaust gas, and reacting a portion of said mixed gas with said hydroxide to form said new gas mixture comprising water removes fluorine from said exhaust gas; 2. The method of claim 1, comprising: estimating the concentration of the fluorine in the portion of the mixed gas based on the detected concentration of the water; 2. The method of claim 1, comprising estimating based solely on the chemical reaction. 2. The method of claim 1, wherein the concentration of said fluorine in said portion of said mixed gas is about 500 to 2000 ppm. 2. The method of claim 1, wherein the reaction between fluorine and said hydroxide in a portion of said gas mixture to form said new gas mixture containing water is stable. reacting the fluorine in a portion of the mixed gas with the hydroxide to form the new gas mixture comprising water is linear and linear with the concentration of the fluorine in the portion of the mixed gas; 2. The method of claim 1, comprising performing a reaction that has a direct correlation with the concentration of said water in said 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 a portion of the gas mixture is also based on the sensed concentration of oxygen. the method of. performing a first gas renewal 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 renewal;
reacting the fluorine in a portion of the withdrawn gas mixture with reactants 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 portion of the mixed gas taken out based on the detected concentration of the water;
adjusting the relative concentration of fluorine in a second gas mixture from the gas supply set based on the estimated concentration of fluorine in the portion of the withdrawn gas mixture; and adjusting the adjusted second gas mixture. performing a second gas renewal by adding a gas mixture from the gas supply to the gas discharge chamber. 28. The method of Claim 27, wherein said reactant comprises a hydroxide. 28. The method of Claim 27, wherein said gas mixture in said gas discharge chamber comprises an excimer laser gas comprising a mixture of at least a gain medium and a buffer gas. estimating the concentration of the fluorine in the part of the mixed gas taken out based on the detected concentration of the water, without measuring the fluorine concentration in the part of the taken out mixed gas; 28. The method of claim 27, comprising estimating the concentration of fluorine in a portion of the gas mixture. An apparatus comprising a detection device fluidly connected to each gas discharge chamber of an excimer gas discharge system and a control system connected to said detection device, each detection device comprising:
a vessel for receiving a reaction cavity containing a hydroxide and fluidly connected to said gas discharge chamber and receiving a fluorine-containing gas mixture from said gas discharge chamber into said reaction cavity; a vessel enabling the reaction of said fluorine and said hydroxide of a mixed gas to form a new gas mixture comprising oxygen and water;
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 is
receiving 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 a gas mixture from a gas delivery system of a gas maintenance system based on the estimated concentration of fluorine in the gas mixture;
a signal instructing the gas maintenance system to adjust the relative concentration of fluorine in a gas mixture supplied to the gas discharge chamber from the gas delivery system of the gas maintenance system during a gas refresh to the gas discharge chamber; An apparatus configured to transmit to said gas maintenance system. 32. The apparatus of Claim 31, wherein each gas discharge chamber of said excimer gas discharge system contains an energy source and contains a gas mixture comprising a gain medium and a fluorine-containing excimer laser gas. the detection device further comprising a measurement vessel fluidly connected to the reaction cavity of the reaction vessel and defining a measurement cavity configured to receive the new gas mixture;
32. The apparatus of Claim 31, wherein the water sensor is configured to sense the amount of water in the fresh gas mixture within the measurement cavity. 32. The apparatus of claim 31, wherein the fluorine concentration in the portion of the mixed gas withdrawn is about 500 to 2000 ppm. 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, the detection device includes a plurality of vessels, each vessel in each of the hydroxylated gas discharge chambers. A reaction vessel containing material is defined, each vessel being fluidly connected to one of said gas discharge chambers, and said sensing device comprising a plurality of water sensors each associated with a vessel. 32. The apparatus of claim 31. 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, the detection device includes a plurality of vessels, each vessel in each of the hydroxylated gas discharge chambers. defining reaction vessels containing material, each vessel fluidly connected to one of said gas discharge chambers, said detection device comprising a single water sensor fluidly connected to all of said vessels; 32. The apparatus of claim 31.

Images