TWI820776B - Fluorine detection in a gas discharge light source - Google Patents

Abstract

A method includes: receiving at least a portion of a mixed gas from a gas discharge chamber, wherein the mixed gas includes fluorine; reacting the fluorine in the mixed gas portion with a hydroxide to form a new gas mixture including oxygen and water; sensing a concentration of water within the new gas mixture; and estimating a concentration of fluorine within the mixed gas portion based on the sensed concentration of water.

Description

Fluorine detection in gas discharge light source

The disclosed subject matter relates to the detection of fluorine in mixed gases.

One type of gas discharge light source used in photolithography is called an excimer light source or laser. Excimer light sources typically use a combination of one or more rare gases, such as argon, krypton, or xenon, and a reactive gas, such as fluorine or chlorine. The name of the excimer light source is derived from the fact that under appropriate conditions of electrical stimulation (supplied energy) and high pressure (of the gas mixture) pseudo-molecules called excimers are produced, which exist only in an energized state and produce effects in the ultraviolet range. Amplify the light.

Excimer light sources generate beams with wavelengths in the deep ultraviolet (DUV) range, and this beam is 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 a plurality of gas discharge chambers.

In some general aspects, a method includes: receiving at least a portion of a mixed gas including fluorine from a gas discharge chamber; reacting the fluorine in the mixed gas portion with a hydroxide to form a gas mixture including oxygen and a new gas mixture of water; sensing a concentration of water in the new gas mixture; and estimating a concentration of fluorine in the mixed gas portion based on the sensed concentration of water.

Implementations may include one or more of the following features. For example, the hydroxide may include an alkaline earth metal hydroxide. The hydroxide may lack an alkali metal and carbon.

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

The method may also include adjusting a relative concentration of fluorine in a gas mixture from a set of gas supplies based on an estimated concentration of fluorine in the portion of the mixed gas; and by transferring the adjusted gas mixture from the gas supplies A device is added to the gas discharge chamber to perform a gas update. The gas renewal may be performed by filling the gas discharge chamber with a gain medium and a mixture of buffer gas and fluorine. The gas discharge chamber may be filled with the mixture of the gain medium and the buffer gas by filling the gas discharge chamber with a gain medium, the gain medium including a rare gas and a halogen, and including one of an inert gas Buffer gas. The rare gas may include argon, krypton, or xenon; the halogen may include fluorine; and the inert gas may include helium or neon. The gas discharge chamber may be filled with the gain medium and the mixture of buffer gas and fluorine by adding the gain medium and the mixture of buffer gas and fluorine to an existing gas discharge chamber. Mixed gas; or at least replace one of the existing mixed gases in the gas discharge chamber with the mixture of the gain medium, the buffer gas and fluorine. The gas renewal may be performed by performing one or more of a gas refilling protocol or a gas injection protocol.

The portion of the mixed gas may be received from the gas discharge chamber by receiving the portion of the mixed gas prior to performing a gas update to the gas discharge chamber. The gas refresh may include adding a gas mixture from a set of gas suppliers to the gas discharge chamber, the gas mixture including at least some fluorine.

The gas renewal may be performed by performing one or more of a gas refilling protocol or a gas injection protocol.

The portion of the mixed gas may be received from the gas discharge chamber by releasing the mixed gas from the gas discharge chamber and directing the released mixed gas to a reaction vessel containing the hydroxide. The method may also include: transferring the new gas mixture from the reaction vessel to a measurement vessel, wherein sensing the concentration of water in the new gas mixture includes sensing the new gas mixture in the measurement vessel The concentration of the water inside. The concentration of water in the new gas mixture can be sensed by exposing a sensor in the measurement vessel to the new gas mixture.

The method may also include discharging the new gas mixture from the measurement vessel after the concentration of fluorine in the mixed gas portion has been estimated.

The concentration of water in the new gas mixture can be sensed by sensing the concentration of water in the new gas mixture without diluting the portion of the mixed gas with another material.

The mixed gas portion may react with the hydroxide by forming an inorganic fluoride compound plus water to form the new gas mixture including water. The hydroxide may include calcium hydroxide, and the inorganic fluoride compound may include calcium fluoride.

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 the reaction has begun.

The mixed gas portion can be a vent gas and the mixed gas portion can react with the hydroxide to form the new gas mixture including water by removing fluorine from the vent gas.

The gas mixture within the gas mixture portion may be estimated based on the sensed concentration of water by estimating based solely on the sensed concentration of water and the chemical reaction between the fluorine and the hydroxide in the gas mixture portion. The concentration of fluorine.

The concentration of fluorine in the mixed gas portion may be about 500 to 2000 parts per million.

The reaction of the fluorine and the hydroxide in the portion of the mixed gas forming the new gas mixture including water is stable.

The fluorine in the mixed gas portion can react with the hydroxide to form the gas mixture including water by performing a reaction that is linear and provides the concentration of fluorine in the mixed gas portion and the new gas There is a direct correlation between the concentration of water in a mixture.

The method may also include sensing a concentration of oxygen within the new gas mixture, and estimating the concentration of fluorine within the mixed gas portion may further be based on the sensed concentration of oxygen.

In other general aspects, a method includes performing a first gas refresh by adding a first gas mixture from a set of gas suppliers to a gas discharge chamber; removing the gas from the gas discharge chamber after the first gas refresh. at least a portion of a mixed gas in the gas discharge chamber, the mixed gas including fluorine; reacting the fluorine in the removed portion of the mixed gas with a reactant to form a new gas mixture including oxygen and water; sensing the a concentration of water in the new gas mixture; an estimate of a concentration of fluorine in the removed portion of the gas mixture based on the sensed concentration of water; an adjustment based on the estimated concentration of fluorine in the removed gas mixture a relative concentration of fluorine in a second gas mixture from the set of gas suppliers; and performing a second gas update by adding an adjusted second gas mixture from the gas suppliers to the gas discharge chamber .

Implementations may include one or more of the following features. For example, the reactants may include hydroxides. The mixed gas in the gas discharge chamber may include an excimer laser gas including at least a mixture of a gain medium and a buffer gas.

The fluorine concentration in the removed mixed gas portion can be estimated based on the sensed concentration of water by estimating the fluorine concentration in the removed mixed gas portion without measuring the fluorine concentration in the removed mixed gas portion. This concentration of fluorine in the portion of the mixed gas removed.

In other general aspects, 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 includes: a container defined to contain a hydroxide and fluidly connected to the gas discharge chamber for receiving one of the mixed gases including fluorine from the gas discharge chamber in the reaction cavity a reaction cavity; and a water sensor. The container enables a reaction between the fluorine and the hydroxide of the received mixed gas to form a new gas mixture including oxygen and water. The water sensor is configured to be fluidly connected to the new gas mixture and, when fluidly connected to the new gas mixture, sense an amount of water within the new gas mixture. The control system is configured to: receive an output from the water sensor and estimate a concentration of fluorine in the mixed gas received from the gas discharge chamber; determine whether the concentration of fluorine in the mixed gas should be based on the concentration of fluorine in the mixed gas. Estimating the concentration to adjust a concentration of fluorine in a gas mixture from a gas supply system of a gas maintenance system; and sending a signal to the gas maintenance system instructing the gas maintenance system to operate in one of the gas discharge chambers The relative concentration of fluorine in a gas mixture supplied from the gas supply system of the gas maintenance system to the gas discharge chamber is adjusted during gas updating.

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

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 new gas mixture. The water sensor may be configured to sense an amount of water in the new gas mixture in the measurement cavity.

The concentration of fluorine in the removed portion of the mixed gas may be about 500 to 2000 parts per million.

The excimer gas discharge system may include a plurality of gas discharge chambers, and the detection device may be fluidly connected to each of the plurality of gas discharge chambers. The detection device may include a plurality of containers, each container defining a reaction cavity containing the hydroxide, and each container fluidly connected to one of the gas discharge chambers and the detection device may include a plurality of water sensors, each water sensor is associated with a container. The detection device may include a plurality of vessels, each vessel defining a reaction cavity containing the hydroxide, and each vessel being fluidly connected to one of the gas discharge chambers and the detection device including A single water sensor with all such containers fluidly connected.

Referring to FIG. 1 , apparatus 100 includes a detection apparatus 105 configured to measure or estimate the concentration of fluorine (F) in gas mixture 107 within chamber 110 using a commercially available fluorine sensor without directly measuring the gas. Fluorine concentration in mixture 107. At room temperature, fluorine is a diatomic molecule gas and is represented by its molecular structure _F2 . The term "fluorine" as used herein therefore refers to 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 in chamber 110 is greater than about 500 parts per million (ppm) and may be about 1000 ppm or up to about 2000 ppm. However, commercially available fluorine sensors usually saturate at 10 ppm, making it impractical to use commercially available fluorine sensors to directly measure the fluorine concentration in the chamber 110 . In effect, detection device 105 implements a chemical reaction that converts fluorine from chamber 110 into one or more components (including water), each of which may utilize the sensing device 116 Commercially available sensors 115 detect and measure. The detection device 105 may calculate or estimate how much fluorine was present before starting the chemical reaction based on the amount of water present after the chemical reaction (as supplied by the sensor 115) and based on information about the chemical reaction.

To make this estimate accurate, detection device 105 may assume that the chemical reaction that converts fluorine from chamber 110 into components is a linear reaction, where the concentration of fluorine before starting the chemical reaction and the concentration of water at the end of the chemical reaction are between There is a direct correlation. Alternatively, the detection device 105 may assume that the conversion of fluorine is complete (and therefore, no residual molecular fluorine _F2 is present in the gas after the chemical reaction).

The apparatus 100 is in communication with a gas maintenance system 120 that includes at least a gas supply system fluidly connected to the chamber 110 via a cannula system 127 . As discussed in detail below, the gas maintenance system 120 includes one or more gas suppliers and a control unit (which also includes a valve system) for controlling which of the gases from the suppliers are transferred into or out of the chamber via the casing system 127 110.

The apparatus 100 includes a controller 130 that receives output from the water sensor 115 and calculates how much fluorine is present before starting a chemical reaction to estimate the amount of fluorine in the gas mixture 107 . Controller 130 uses this information to determine whether the fluorine concentration in gas mixture 107 needs to be adjusted. Controller 130 therefore determines how to adjust the relative amounts of gas in the supplies of gas maintenance system 120 to be transferred into or 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 gas refresh of chamber 110 .

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 sleeve 137 to receive mixed gas 150 including fluorine from chamber 110 . Although not shown, one or more fluid control devices (such as valves) may be placed in cannula 137 to control the timing of when mixed gas 150 is directed to reaction cavity 140 , and to control the flow of mixed gas 150 into reaction vessel 135 the rate. In this manner, the reaction cavity 140 enables a chemical reaction between the fluorine and the hydroxide 145 of the received mixed gas 150 to form a new gas mixture 155 . The interior of the reaction vessel 135 defining the reaction cavity 140 should be made of non-reactive material so as not to interfere with or alter the chemical reaction between the fluorine and the hydroxide 145 of the received mixed gas 150 . For example, the interior of reaction vessel 135 may be made of non-reactive metal such as stainless steel or Monel metal.

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

The water sensor 115 (and optionally the oxygen sensor 117 ) may be inside the measurement cavity 175 of the measurement container 170 . Measuring cavity 175 is fluidly connected to reaction cavity 140 via cannula 177 . Although not shown in FIG. 1 , one or more fluid control devices (such as valves) may be placed in cannula 177 to control the timing of when new gas mixture 155 is directed to measurement cavity 175 , as well as to control the timing of new gas mixture 155 The rate of flow into the measurement container 170.

In some implementations, water sensor 115 may be a hygrometer that measures the amount of water vapor or humidity in cavity 175 . Tools that measure humidity often also measure mechanical or electrical changes in temperature, pressure, mass, or even substances that absorb moisture, since these factors can also affect humidity. Through calibration and calculation, these measured quantities can lead to measurements of humidity. A hygrometer can be an electronic device that uses the condensation temperature (also called the dew point), the point of complete vapor saturation of a substance. A hygrometer is a device that detects and measures changes in the capacitance or resistance of a substance to determine humidity. A hygrometer may be a resistive hygrometer that measures changes in a substance's ability to hold an electrostatic charge. A hygrometer may be a capacitor-based hygrometer that measures changes in a substance's ability to transmit electricity.

In some implementations, although not required, the sensing device 116 includes a second sensor 117 , which may be for sensing oxygen in the new gas mixture 155 in the range of 200 to 1000 parts per million (ppm). Sensor 117.

An example of an oxygen sensor 117 suitable for this concentration range is an oxygen analyzer, which utilizes a precision zirconium dioxide sensor to detect oxygen. Zirconia sensors include units made of high-purity, high-density, stable zirconia ceramics. The zirconium dioxide sensor generates a voltage signal indicative of the oxygen concentration of the new gas mixture 155 . Additionally, the output of the zirconium dioxide sensor is 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 dioxide unit includes a zirconium dioxide ceramic tube with porous platinum electrodes electroplated on its inner and outer surfaces. When a zirconium dioxide sensor is heated above a certain temperature (such as 600 C or 1112°F), it becomes an oxygen ion conducting electrolyte. The electrode provides a catalytic surface for the change of oxygen molecules _O2 to oxygen ions and oxygen ions to oxygen molecules. Oxygen molecules on the high-concentration reference gas side of the cell gain electrons to become ions that enter the electrolyte. At the same time, at the inner electrode, the oxygen ions lose their electrons and are released from the surface as oxygen molecules. When the oxygen concentration on each side of the zirconium dioxide sensor is different, oxygen ions migrate from the high concentration side to the low concentration side. This ion flow creates an electron imbalance, resulting in a DC voltage across the electrodes. This voltage is a function of the sensor temperature and the ratio of the oxygen partial pressure (concentration) on each side of the sensor. This voltage is then analyzed by a high-speed microprocessor within the oxygen sensor 117 to be read directly by the controller 130 .

Since the chemical reaction between fluorine and hydroxide is a stoichiometrically simple chemical reaction that is easy to implement and control, the fluorine in the mixed gas 150 reacts with the hydroxide 145 . Furthermore, the controlled stoichiometric ratios of chemical reactions are fixed. In addition, the chemical reaction between fluorine and hydroxide is a stable chemical reaction. A chemical reaction may be stable if it is not reversed and the components of the new gas mixture do not react with anything else in the new gas mixture to form fluorine. Next, a suitable chemical reaction between fluorine and hydroxide 145 in a stable and controlled stoichiometric gas mixture 150 is discussed.

In some implementations, hydroxide 145 is in particulate, solid, or powder form. Additionally, hydroxide 145 in particulate form can be tightly packed into reaction vessel 135 (which can be a tube) such that there is no movement of the particles in the powder of hydroxide 145 . The areas or volumes outside the powder of hydroxide 145 and in the space within reaction vessel 135 are considered pores, and by using hydroxide 145 in particulate form, it is possible to ensure that a larger surface area is present to allow hydroxide 145 to interact with Full chemical reaction between fluorine. In some implementations, and 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.

Hydroxide 145 may fill reaction cavity 140 within reaction vessel 135. The shape of reaction vessel 135 (and thus reaction cavity 140) is not limited to a particular form.

Hydroxide 145 includes metal Σ, which may be an alkaline earth metal. In addition, hydroxide 145 lacks alkali metals and carbon. Thus, hydroxide 145 may be calcium hydroxide [Ca(OH) ₂ ] (in this example, Σ is Ca). Calcium hydroxide is in particulate and solid form and is sufficiently porous 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 achieve chemical reactions. For example, the calcium hydroxide may be in the form of particles that are packed into a row and the level of packing depends on the level of fluorine concentration in the gas mixture 150 to be analyzed. Mixed gas 150 is passed (eg, flowed) through or across hydroxide 145 to effect a chemical reaction between fluorine and calcium hydroxide.

In the case where fluorine gas (F ₂ ) exists in the mixed gas 150, if 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) OF ₂ + Ca(OH) ₂ = CaF ₂ + O ₂ + H ₂ O. For every two molecules of fluorine (F ₂ ) interacting with molecules of calcium hydroxide [Ca(OH) ₂ ] 145, output two molecules of the inorganic fluoride compound (calcium fluoride or CaF ₂ ), oxygen (O One molecule of ₂ ) and two molecules of water (H ₂ O). This chemical reaction is a linear and stoichiometrically simple reaction. Therefore, to focus only on fluorine and water, for every molecule of fluorine _F2 input into the chemical reaction, one molecule of water _H2O is output from the chemical reaction. Another way of writing this is that for every mole of fluorine _F2 input into the chemical reaction, one mole of _H2O is output from the chemical reaction. Therefore, if 2 moles of fluorine _F2 are input into a chemical reaction, 2 moles of water _H2O are released after the chemical reaction. This water is detected by water sensor 115. Therefore, for example, since the controller 130 (accessing data from the stored memory) knows that the ratio of fluorine to water in this chemical reaction is 1:1, if the sensor 115 detects 0.6 moles of water, the controller 130 determines that there are 0.6 moles of fluorine in the gas mixture 107 . In other implementations, the detection device 105 may assume that the conversion of fluorine is complete (and therefore, no residual molecular fluorine _F2 is present in the gas after the chemical reaction). For example, this assumption may be valid if sufficient time has elapsed since the chemical reaction was initiated.

In this example, if the sensing device 116 also includes an oxygen sensor 117 , the measurement of the concentration of oxygen from the oxygen sensor 117 may be used in conjunction with the measurement of water from the water sensor 115 . Therefore, if 4 moles of fluorine F ₂ are input into a chemical reaction, 2 moles of oxygen O ₂ are released after the chemical reaction. This oxygen is detected by oxygen sensor 117. As an example, since the controller 130 knows that the ratio of fluorine to oxygen in this chemical reaction is 2:1, if 0.3 moles of oxygen are detected by the sensor 117, the controller determines that the gas mixture 107 contains 0.6 moles of fluorine are present. Controller 130 may use data from both oxygen sensor 117 and water sensor 115 to estimate the concentration of fluorine present in gas mixture 107 (since the weights or masses of oxygen, water, and fluorine are known ). For example, two data sets can be used to make a more accurate determination of fluorine. Additional calibrations and corrections may also be used by the controller (eg to account for fluorine, oxygen or water consumption or inefficient detection), as will be understood by those skilled in the art.

In some implementations, the reaction between the hydroxide 145 and the fluorine in the gas mixture 150 occurs under one or more specifically designed conditions. For example, the reaction between the hydroxide 145 and the fluorine in the mixed gas 150 may occur in the presence of one or more catalysts that alter the rate of the chemical reaction but are chemically inert at the end of the chemical reaction. The substance of change. As another example, the reaction between the hydroxide 145 and the fluorine in the mixed gas 150 may occur in a controlled environment such as a temperature-controlled environment or a humidity-controlled environment.

Referring to FIG. 2 , the apparatus 100 may be implemented, for example, within an ultraviolet (UV) or deep ultraviolet (DUV) light source 200 that generates a beam of light directed to a photolithography apparatus 222 for patterning microelectronic features on a wafer. 211. The light source 200 includes a control system 290 connected to various components of the light source 200 to achieve generation of the light beam 211. Although control system 290 is shown as a single piece, it may be made from a plurality of sub-assemblies, any one or more of which may be removable from other sub-assemblies or local components within light source 200 . Additionally, controller 130 may be considered part of control system 290 or part of device 100 .

In this implementation, 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 beam 211 of the light source 200 . Although only one gas discharge chamber 210 is shown, the excimer gas discharge system 225 may include a plurality of gas discharge chambers 210 , any one or more of which are associated with the detection device 105 of the device 100 and other components such as optical components, Metrology devices and electromechanical components) are in fluid communication for controlling the light beam 211, such other components are not shown in Figure 2. Furthermore, only components of the light source 200 associated with the device 100 are shown in FIG. 2 . For example, the light source 200 may include a beam preparation system placed at the output of the last gas discharge chamber 210 to adjust one or more properties of the beam 211 directed to the photolithography apparatus 222 .

Gas discharge chamber 210 houses an energy source 230 and contains a gas mixture 207 . Energy source 230 provides a source of energy to gas mixture 207; specifically, energy source 230 provides sufficient energy to gas mixture 207 to cause population inversion, thereby achieving gain via stimulated emission within chamber 210. In some examples, energy source 230 is a discharge provided by a counter electrode placed within gas discharge chamber 210 . In other examples, energy source 230 is an optical pump source.

Gas mixture 207 includes gain media including noble gases and halogens, such as fluorine. During operation of the DUV light source 200 , fluorine is consumed in the gas mixture 207 within the gas discharge chamber 210 (which provides the gain medium for light amplification), and over time this reduces the amount of light amplification and therefore changes produced by the light source 200 Characteristics of the beam 211. The photolithography apparatus 222 attempts to maintain the fluorine concentration in the gas mixture 207 in the gas discharge chamber 210 within a certain tolerance compared to the fluorine concentration set during the initial gas refill procedure. Thus, additional fluorine is added to the gas discharge chamber 210 at a regular pace and under the control of the gas maintenance system 120 . Fluorine consumption varies between gas discharge chambers, so closed loop control is used to determine the amount of fluorine to push or inject into gas discharge chamber 210 at each opportunity. The apparatus 100 is used in an overall scheme to determine the concentration of fluorine remaining in the gas discharge chamber 210 and therefore the amount of fluorine to be pushed or injected into the gas discharge chamber 210 .

As mentioned, gas mixture 207 includes a gain medium including noble gases and fluorine. Gas mixture 207 may include other gases, such as buffer gases. The gain medium is a laser active entity within the gas mixture 207, and the gain medium can be composed of single atoms, molecules or pseudo-molecules. Thus, population inversion is produced in the gain medium by pumping the gas mixture 207 (and therefore the gain medium) with a discharge from the energy source 230 via stimulated emission. As mentioned above, the gain medium usually includes rare gases and halogens, and the buffer gas usually includes inert gases. Rare 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 (rare gases or noble gases), and therefore, it is assumed that the only chemical reaction occurring between the mixed gas 150 and the hydroxide 145 is the fluorine in the mixed gas 150 and the hydroxide 145 . Reactions between hydroxides 145.

Referring again to FIG. 1 , gas maintenance system 120 is a gas management system for adjusting characteristics such as the relative concentration or pressure of components within gas mixture 107 or 207 .

Referring to Figure 3, in some implementations in which 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 and the detection device 105 is A detection device 305 includes a fluorine sensor 360 fluidly connected to the reaction cavity 140 and configured to determine when the concentration of fluorine in the new gas mixture 155 falls below a lower limit value. The fluorine sensor 360 may be a commercially available fluorine sensor that saturates at a concentration higher than fluorine, which is too low for direct measurement of fluorine in the mixed gas 150 . However, the fluorine sensor 360 has a minimum detection threshold and can be used to thereby detect when the concentration of fluorine in the new gas mixture 155 drops below the lower limit. For example, the fluorine sensor 360 may saturate at a concentration of 10 ppm, but may have a minimum detection threshold of approximately 0.05 ppm and may reduce the fluorine concentration in the new gas mixture 155 to less than 0.1 ppm. Then detection of fluorine in the new gas mixture 155 begins.

Controller 130 is configured to receive output from fluorine sensor 360 . Controller 330 includes modules that interact with flow control device 365 along the line that delivers new 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.

Controller 330 sends a signal to flow control device 365 to enable fresh gas only when the concentration of fluorine in fresh gas mixture 155 is determined to have fallen below a lower limit value (eg, 0.1 ppm) from the output of fluorine sensor 360 Mixture 155 can flow to oxygen sensor 117 . In this manner, oxygen sensor 117 is only exposed to new gas mixture 155 if the fluorine concentration drops below the lower limit, thereby protecting oxygen sensor 117 from unacceptable fluorine levels. The lower limit value may be a value determined based on the damage threshold of the oxygen sensor 117 . Therefore, at a fluorine concentration higher than the lower limit value, the oxygen sensor 117 may be damaged. 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, the measurement error may affect the accuracy of the oxygen sensor 117 .

The detection device 305 also includes a measurement vessel 370 fluidly connected to the reaction cavity 140 of the reaction vessel 135 . Measuring vessel 370 defines a measuring cavity 375 configured to receive new gas mixture 155 . In addition, the water sensor 115 and the oxygen sensor 117 are accommodated in the measurement cavity 375 . The measurement container 370 is any container that contains the new gas mixture 155 such that the water sensor 115 can sense the concentration of water in the new gas mixture 155 and the oxygen sensor 115 can sense the concentration of oxygen in the new gas mixture 155 . container. The interior of the measuring vessel 370 defining the measuring cavity 375 should be made of non-reactive material so as not to change the composition of the new gas mixture 155 . For example, the interior of measurement container 370 may be made of non-reactive metal.

Referring to FIG. 4 , in some implementations, device 100 is designed as device 400 and detection device 105 is designed as detection device 405 , which includes a buffer vessel 470 from the reaction vessel 135 required. The flow rate decouples the flow rate of the exhaust gas from chamber 110 . In this manner, the buffer vessel 470 achieves fluorine measurement via the detection device 405 without affecting the steady-state operation of gas exchange by the gas maintenance system 120 .

In one example, the concentration of fluorine in the chamber 110 is about 1000 ppm, the volume of the chamber 110 is 36 liters (L), and the pressure in the chamber 110 is 200 to 400 kPa. The internal cavity of the buffer container 470 has a volume of approximately 0.1 L and a pressure of 200 to 400 kPa. The measurement cavity 175 has a volume of 0.1 L, a pressure of approximately 200 to 400 kPa, a water concentration of 1000 ppm, and an oxygen concentration of approximately 500 ppm. After the water sensor 115 measures the water concentration (and optionally the oxygen sensor 117 measures the oxygen concentration) and outputs the data to the controller 130 , the measurement cavity 175 may then be emptied in a controlled manner. .

As mentioned above with reference to FIG. 1 , the apparatus 100 is configured to measure or estimate the concentration of fluorine in the gas mixture 107 in the chamber 110 . In some implementations, as shown in Figure 5, device 100 is designed as device 500 and detection device 105 is designed as detection device 505 configured to measure or estimate respective chambers 510_1 , the concentration of fluorine in the gas mixture 507_1, 507_2...507_i in 510_2...510_i, where i is an integer greater than 1. Within the detection device 505, there are independent or dedicated sensing devices 516_1, 516_2...516_i associated with the respective chambers 510_1, 510_2...510_i. In this manner, each sensing device 516_1, 516_2...516_i can be used to measure the fluorine concentration in the respective chamber 510_1, 510_2...510_i.

The detection device 505 is connected to a gas maintenance system 520 that includes a gas supply system fluidly connected to each chamber 510_1, 510_2...510_i via a respective sleeve system 527_1, 527_3...527_i, the respective sleeve Pipe systems 527_1, 527_3...527_i are part of the main casing system 527. The gas maintenance system 520 includes one or more gas suppliers and a control unit for controlling which of the gases from the suppliers the view main casing system 527 transfers into and out of the respective chambers 510_1, 510_2...510_i. The detection device 505 includes respective reaction vessels 535_1, 535_2...535_i that receive mixed gases 550_1, 550_2...550_i (including fluorine) from respective chambers 510_1, 510_2...510_i via respective sleeves 537_1, 537_2...537_i. New gas mixtures 555_1, 555_2...555_i are then conducted from the chemical reaction between the fluorine and hydroxides 545_1, 545_2...545_i of the mixed gases 550_1, 550_2...550_i received in the respective reaction vessels 535_1, 535_2...535_i. to respective sensing devices 516_1, 516_2...516_i.

Detection device 505 also includes a controller 530 connected to gas maintenance system 520 and to each of sensing devices 516_1, 516_2...516_i. Like controller 530, controller 530 receives output from sensing devices 516_1, 516_2...516_i and calculates or estimates how much fluorine is present before starting a chemical reaction in reaction vessels 535_1, 535_2...535_i to estimate respective gas mixtures 507_1, 507_2...507_i The amount of fluorine in it.

In other implementations, it is possible to use a single sensing device 516 that measures fluorine in all chambers 510_1, 510_2...510_i, as long as the detection device 505 includes appropriate coordination between the chambers 510_1, 510_2...510_i and the detection device 505 ducting to prevent crosstalk between measurements made by sensing device 516 for each of chambers 510_1, 510_2...510_i. Additionally, if only one chamber 510 is gas exchanged at a time, a single sensing device 516 design may function, and thus the controller 530 may measure fluorine in a single chamber 510 at any one time.

Referring to FIG. 6 , an exemplary DUV light source 600 is shown with a detection device 605 such as detection device 105 and a controller 630 such as controller 130 of FIGS. 1 , 3 , 4 or 5 . The DUV light source 600 includes an excimer gas discharge system 625 designed for dual stage pulse output. The gas discharge system 625 has two stages: a first stage 601, which is a master oscillator (MO) that outputs a pulsed amplified beam 606; and a second stage 602, which is an amplified beam from the first stage. Station 601 receives the power amplifier (PA) of beam 606. 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. The two elongated electrodes 630_2 provide the source of energy to the gas mixture 607_2 in the chamber 610_2.

MO 601 provides beam 606, which may be referred to as a seed beam, to PA 602. MO gas discharge chamber 610_1 houses a gas mixture 607_1 including a gain medium in which amplification occurs, and MO 601 also includes optical feedback mechanisms, such as a spectral feature selection system 680 formed on one side of MO gas discharge chamber 610_1 and the MO gas The optical resonator between the output coupler 681 on the second side of the discharge chamber 610_1.

PA gas discharge chamber 610_2 contains a gas mixture 607_2 including a gain medium 607_2 in which amplification occurs when seed beam 606 from MO 601 is spread. If the PA 602 is designed as a regenerative ring resonator, it is described as a power ring amplifier (PRA), and in this case can provide sufficient optical feedback from the ring design. PA 602 includes a return beam 682 that returns the beam (eg, via reflection) into the PA gas discharge chamber 610_2 to form a circulating and closed loop path, where input into the loop amplifier is at beam coupling device 683 and exits the loop amplifier. The outputs intersect.

MO 601 enables fine tuning of spectral parameters, such as center wavelength and bandwidth, at relatively low output pulse energies (when compared to the output of PA 602). The PA receives seed beam 606 from MO 601 and amplifies this output to obtain the necessary power for output beam 211 for use in an output device such as photolithography device 222. The seed beam 606 is amplified by repeatedly passing through the PA 602 and the spectral characteristics of the seed beam 606 are determined by the configuration of the MO 601 .

The gas mixtures 607_1, 607_2 used in the respective gas discharge chambers 610_1, 610_2 may be those of suitable gases for producing amplified beams of approximately the desired wavelength and bandwidth, such as the seed beam 606 and the output beam 211. combination. 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.

The detection device 605 includes a gas maintenance system 620, which is a gas management system for the excimer gas discharge system 625 and in particular for the gas discharge chambers 610_1 and 610_2. Gas maintenance system 620 includes one or more gas sources 651A, 651B, 651C, etc. (such as sealed gas bottles or tanks) and valve system 652. One or more gas sources 651A, 651B, 651C, etc. are connected to the MO gas discharge chamber 610_1 and the PA gas discharge chamber 610_2 via a collection of valves within a valve system 652. In this manner, gas may be injected into the respective gas discharge chamber 610_1 or 610_2 in specific relative amounts of the components within the gas mixture. Although not shown, gas maintenance system 620 may also include one or more other components, such as flow restrictors, vent valves, pressure sensors, gauges, and test ports.

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 halogens, such as fluorine, and other gases, such as argon, neon, and possibly other gases at different partial pressures that add up to the total pressure. For example, if the gain medium used in the gas discharge chambers 610_1 and 610_2 is argon fluoride (ArF), the gas source 651A contains halogen fluorine, rare gas argon and one or more other rare gases, such as buffer gases. (which may be a gas mixture of inert gases such as neon). This mixture within gas source 651A may be referred to as triple gas since it contains three types of gases. In this example, another gas source 651B may contain a gas mixture including argon and one or more other gases but no fluorine. This mixture in gas source 651B may be called a binary gas since it contains two types of gases.

Gas maintenance system 620 may include valve controller 653 configured to send one or more signals to valve system 652 to cause valve system 652 to divert gas from particular gas sources 651A, 651B, 651C, etc., in a gas update. in the gas discharge chambers 610_1 and 610_2. The gas refresh may be a refill of the gas mixture 607 in the gas discharge chamber, wherein at least the existing mixed gas in the gas discharge chamber is replaced with a mixture of gain medium and buffer gas and fluorine. The gas refresh may be an injection scheme in which a mixture of gain medium and buffer gas and fluorine is added to the existing gas mixture in the gas discharge chamber.

Alternatively or in addition, the valve controller 653 may send one or more signals to the valve system 652 to cause the valve system 652 to bleed gas from the discharge chambers 610_1, 610_2 as necessary, and such bleed gas may be vented to the 689 gas dumping. In some implementations, it is possible that the evolved gas is instead fed to detection device 605, as shown in Figure 7.

During operation of the DUV light source 600, fluorine is consumed from the argon (or krypton) fluoride molecules (which provide the gain medium for light amplification) within the gas discharge chambers 610_1, 610_2, and this reduces the amount of light amplification over time. and thus reducing the energy of the beam 211 used by the photolithography apparatus 222 for wafer processing. In addition, 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 from one or more of the gas sources 651A, 651B, 651C, etc. into the gas discharge chambers 610_1, 610_2 in order to flush contaminants or replenish lost fluorine.

A plurality of gas sources 651A, 651B, 651C, etc. are required because the fluorine in gas source 651A is at a specific partial pressure that is typically higher than that required for laser operation. In order to add fluorine to gas chamber 610_1 or 610_2 at a desired lower partial pressure, the gas in gas source 651A can be diluted, and a halogen-free gas in gas source 651B can be used for this purpose.

Although not shown, the valves of valve system 652 may include a plurality of valves assigned to each of gas discharge chambers 610_1 and 610_2. For example, an injection valve that allows gas to enter and exit each gas discharge chamber 610_1, 610_2 at a first flow rate may be used. As another example, a chamber filling valve may be used that allows gas to enter and exit each gas discharge chamber 610_1, 610_2 at a second flow rate that is different from the first flow rate (eg, faster).

In a refilling scheme for gas discharge chamber 610_1 or 610_2, for example by clearing gas discharge chamber 610_1 or 610_2 (by venting the gas mixture to gas dump 689) and then refilling the gas discharge chamber with fresh gas mixture Chamber 610_1 or 610_2 to replace all the gas in the gas discharge chamber 610_1 or 610_2. Refilling is performed to obtain a specific pressure and fluorine concentration in the gas discharge chamber 610_1 or 610_2. When the gas discharge chamber 610_1 or 610_2 is subjected to an injection scheme, the gas discharge chamber is not emptied or only emits a small amount before the gas mixture is injected into the gas discharge chamber. In the two-gas update, the detection device 605 (which is designed similarly to the detection device 105) may receive some of the released gas mixture as the mixed gas 150 for analysis in the detection device 605, thereby determining the gas discharge chamber. The concentration of fluorine in chamber 610_1 or 610_2 is used to determine how to perform gas renewal.

Valve controller 653 interfaces with detection device 605 (and in particular with controller 130 in detection device 605). Additionally, valve controller 653 may interface with other control modules and subcomponents that are part of control system 690, discussed next.

Referring to Figure 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 regarding the control system 790 with respect to the detection device 105/605 described herein and with respect to the methods of gas control and fluorine concentration estimation. Additionally, control system 790 may include other features not shown in FIG. 7 . Generally speaking, the control system 790 includes one or more of digital electronic circuits, computer hardware, firmware, and software.

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 all forms of non-volatile memory, including (by way of example) semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks, such as internal Hard drives and removable disks; magneto-optical disks; and 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).

Control system 790 includes one or more programmable processors 715 and one or more computer programs tangibly embodied in a machine-readable storage device for execution by a programmable processor, such as processor 715 Product 720. One or more programmable processors 715 can each execute program instructions to perform desired functions by operating on input data and producing appropriate output. Generally speaking, processor 715 receives instructions and data from memory 700 . Any of the foregoing may be supplemented by or incorporated into a specially designed ASIC (Application Special Integrated Circuit).

The control system 790 may also include, among other components or modules, the controllers 130, 330, 530 of the detection device 105 (shown as block 730 in Figure 7) and interface with the valve controller 653 of the gas maintenance system 620. 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 . In addition, any one of the controller 730/module 731 can access the data stored in the memory 700.

Connections between controllers/features/modules within control system 790 and between controllers/features/modules within control system 790 and other components of device 100 (which may be DUV light source 600 ) may be wired or wireless. of.

Although only a few modules are shown in Figure 7, control system 790 may include other modules. Additionally, although control system 790 is shown as a block in which all components appear to be co-located, control system 790 may be composed of components that are physically remote from each other in space or time. 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 .

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 .

Referring to Figure 8, in some implementations, device 100 is designed as device 800 and detection device 105 is designed as detection device 805 operating in parallel with fluorine scrubber 804, which is in fluid communication with gas maintenance system 820 . The fluorine scrubber 804 is used in conjunction with the gas maintenance system 820 to properly vent the gas mixture 807 from the chamber 110 by chemically reacting the fluorine within the gas mixture 807 to form chemicals that can be safely processed, such as via an exhaust device. .

A portion of the mixed gas 150 released from the gas maintenance system 820 is directed to a buffer vessel 870 and then to another fluorine scrubber 835 including a hydroxide 845. The fluorine in the gas mixture 150 chemically reacts with the hydroxide 845 in the fluorine scrubber 835 (in the manner discussed above) and is converted into a new gas mixture 155 including oxygen. The new gas mixture 155 is directed to the sensing device 116 where it is sensed. The controller 130 estimates the oxygen concentration and the fluorine concentration in the mixed gas 150 and the gas mixture 107 and determines how to adjust the gas maintenance system 820 for gas renewal. In this example, gas maintenance system 820 includes valve system 852 fluidly connected to triple gas source 851A and dual gas source 851B. Various control valves 891 are placed along the lines to control the flow rate and control the amount of gas directed across the lines.

Referring to FIG. 9 , a process 900 is performed by the apparatus 100 for detecting the concentration of fluorine in the gas mixture 107 of the chamber 110 . Reference is made to the device of Figure 1, but the process 900 is equally applicable to the device described with reference to Figures 2-8. The detection device 105 receives a portion of the mixed gas 150 including fluorine from the gas discharge chamber 110 (905). The fluorine in the gas mixture 150 chemically reacts with the hydroxide 145 to form a new gas mixture 155 including water (910). For example, the sensor 115 is used to sense the concentration of water in the new gas mixture 155 (915). And, the concentration of fluorine in the mixed gas 150 is estimated based on the sensed concentration of water (920). For example, the controller 130 may estimate the concentration of fluorine in the mixed gas 150 based on the output from the water sensor 115 .

Detection device 105 may receive gas mixture 150 by venting gas mixture 107 from chamber 110 (releasing negative pressure) (905). For example, gas maintenance system 120 may include a series of valves that enable gas mixture 107 to be released from chamber 110 and subsequently directed as mixed gas 150 to detection device 105 . The pressure in the chamber 110 can be used to pressurize the reaction vessel 135 or the buffer vessel 470 , such as by using a series of valves and vacuum pumps to create negative pressure, pushing the gas mixture 107 out of the chamber 110 and to the detection device 105 . The amount of mixed gas 150 required in the reaction vessel 135 may be determined based on the requirements of the water sensor 115 to obtain 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, there is a need to have accurate readings from the water sensor 115, but also to minimize the total air flow so that the hydroxide 145 can have maximum service life.

The mixed gas 150 received (905) by the detection device 105 may be the mixed gas 150 discharged from the chamber 110 toward the fluorine scrubber, and therefore the mixed gas 150 may be regarded as the exhaust gas. This implementation is shown in Figure 8, where the fluorine in the mixed gas 150 chemically reacts with the hydroxide 845 in the fluorine scrubber 835 and is converted into a new gas mixture 155 including oxygen.

Process 900 may be performed to predict gas updates, such as gas refills or gas injections. For example, the first gas refresh may be performed by adding the first gas mixture from the gas maintenance system 120 to the chamber 110, and after using the chamber 110 for a certain period of time, the process 900 may be performed. After performing process 900, a second gas refresh may then occur by adding an adjusted second gas mixture from the gas maintenance system 120 to the chamber 110. The adjusted second gas mixture has a concentration of fluorine (or an amount of fluorine) that may be based on measurements made by process 900 .

Fluorine can chemically react with hydroxide 145 (910) by forming an inorganic fluoride compound coupled with water and oxygen. This inorganic fluoride compound (which is present in the new gas mixture 155 ) does not interact with the water sensor 115 .

After chemically reacting fluorine with hydroxide 145 to form new gas mixture 155 (910), new gas mixture 155 may be transferred from reaction vessel 135 to measurement vessel 170 to enable sensing of new gas mixture 155 The concentration of water in (915). The concentration of water in the new gas mixture 155 can therefore be sensed by exposing the sensor 115 in the measurement container 170 to the new gas mixture 155 (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.

Furthermore, after the chemical reaction (910) has started, it may be appropriate to wait for sensing the concentration of water in the new gas mixture 155 (915) until or only after a predetermined time period has elapsed. This will ensure that sufficient fluorine in the gas mixture 150 has been converted to water and inorganic fluoride compounds before the water sensor 115 is exposed to the new gas mixture 155 . Depending on the relative amounts of fluorine in the gas mixture 150 and the total volume of hydroxide 145, it may take several seconds or several minutes to completely convert the fluorine into water.

In some implementations, the chemical reaction (910) system may be performed by passing the mixed gas 150 at a low velocity (eg, about 0.1 slpm or less) across or through the hydroxide 145 to form a new gas mixture 155 at a specific flow rate. possible. In this situation, water can be sensed in a continuous manner (915). The concentration of fluorine (920) may be estimated from the integration of the sensed water measurements (915) over a period of time or when the sensed water measurements (915) have reached a steady state.

The fluorine in the new gas mixture 155 is estimated (920) based on the sensed concentration of water (915) and also based on knowledge of the chemical reactions that convert the fluorine in the gas mixture 150 to water.

After completion of procedure 900 (ie, after the concentration of fluorine in the gas mixture 150 has been estimated at 920), the new gas mixture 155 is then drained (removed) from the measurement vessel 170 to permit the same for a new batch of the gas mixture. 150 proceeds to procedure 900.

Referring to Figure 10, once the fluorine concentration is estimated (920) and after process 900 is completed, process 1000 is performed by device 100. Gas maintenance system 120 receives output from controller 130 of detection device 105 and adjusts the relative concentration of fluorine in the gas mixture from a set of gas suppliers (such as gas sources 651A, 651B, 651C, etc.) based on the estimated concentration of fluorine. (1005). The gas maintenance system 120 performs gas renewal (1010) by adding a modified gas mixture to the chamber 110 through the casing system 127 until the pressure within the chamber 110 reaches the desired level. Gas updates may be accomplished and tracked by monitoring the timing of valves within the gas maintenance system 120 .

For example, referring to Figure 2, gas updating (1010) may include filling the gas discharge chamber 210 with a mixture of a gain medium including a noble gas and a buffer gas and fluorine, where the gain medium includes a noble gas and fluorine and the buffer gas includes an inert gas. It is possible to delay the gas update (1010) relative to when the fluorine concentration estimate (900) is made. In some implementations, if the controller 130 determines that the concentration of fluorine in the gas mixture 107 has dropped below an acceptable level, the estimation (900) may be followed by an adjustment (1005) and a gas update (1010). In some implementations, it may be possible to delay fluorine adjustment (1005) until it is determined that the concentration of fluorine in gas mixture 107 has dropped below an acceptable level. For example, if the controller 130 determines that the concentration of fluorine in the gas mixture 107 is still high, but the device 100 must perform a gas refresh for other reasons, it may be possible to perform a gas refresh without increasing the fluorine in the gas mixture 107 level as the target.

Referring to FIG. 11 , in some implementations, the detection device 305 performs process 1100 instead of process 900 to estimate the fluorine concentration in the mixed gas 150 . Process 1100 is similar to process 900 and includes the following steps: receiving a portion of the mixed gas 150 including fluorine from the gas discharge chamber 110 (905); and chemically reacting the fluorine in the mixed gas 150 with the hydroxide 145 to form a mixture including fluorine and fluorine. New gas mixtures of water and oxygen 155 (910). Process 1100 determines whether the fluorine concentration in new gas mixture 155 has fallen below a lower limit (1112). For example, fluorine sensor 360 fluidly connected to reaction cavity 140 may make this determination (1112) and controller 330 may proceed only if the concentration of fluorine in new gas mixture 155 has dropped below The step of instructing the sensing device 116 to sense both the concentration of water (via the sensor 115 ) and the concentration of oxygen (via the sensor 117 ) in the new gas mixture 155 ( 915 ) is only when the lower limit value is reached ( 1112 ). As previously described, the concentration of fluorine in the mixed gas 150 is estimated based on the sensed concentration of oxygen (920).

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

Other aspects of the invention are set forth in the following numbered items. 1. A method comprising: receiving at least a portion of a mixed gas from a gas discharge chamber, wherein the mixed gas includes fluorine; reacting the fluorine in the mixed gas portion with a hydroxide to form a new gas mixture including oxygen and water; sensing a concentration of water in the new gas mixture; and A concentration of fluorine within the mixed gas portion is estimated based on the sensed concentration of water. 2. The method of clause 1, wherein the hydroxide includes an alkaline earth metal hydroxide. 3. The method of item 1, wherein the hydroxide lacks an alkali metal and carbon. 4. The method of item 1, wherein the mixed gas is an excimer laser gas including at least a mixture of a gain medium and a buffer gas. 5. The method of item 1, which further includes: Adjust the relative concentration of fluorine in a gas mixture from a set of gas supplies based on the estimated concentration of fluorine in that portion of the gas mixture; and A gas refresh is performed by adding an adjusted gas mixture from the gas suppliers to the gas discharge chamber. 6. The method of clause 5, wherein performing the gas updating includes filling the gas discharge chamber with a gain medium and a mixture of buffer gas and fluorine. 7. The method of clause 6, wherein filling the gas discharge chamber with the mixture of the gain medium and the buffer gas includes: filling the gas discharge chamber with a gain medium, the gain medium including a rare gas and a halogen , and a buffer gas including an inert gas. 8. The method of clause 7, wherein the rare gas includes argon, krypton or xenon; the halogen includes fluorine; and the inert gas includes helium or neon. 9. The method of clause 6, wherein filling the gas discharge chamber with the mixture of the gain medium and the buffer gas and fluorine includes: Add the mixture of the gain medium and the buffer gas and fluorine to an existing gas mixture in the gas discharge chamber; or Replace at least one of the existing mixed gases in the gas discharge chamber with the mixture of the gain medium and the buffer gas and fluorine. 10. The method of clause 5, wherein performing the gas renewal includes: performing one or more of a gas refilling program or a gas injection program. 11. The method of clause 1, wherein receiving at least the portion of the mixed gas from the gas discharge chamber includes: receiving the portion of the mixed gas before performing a gas update on the gas discharge chamber, wherein the gas update includes A gas mixture is added to the gas discharge chamber from a set of gas supplies, wherein the gas mixture includes at least some fluorine. 12. The method of clause 11, wherein performing the gas update includes: performing one or more of a gas refilling program or a gas injection program. 13. The method of clause 1, wherein receiving at least the portion of the mixed gas from the gas discharge chamber includes: releasing the mixed gas from the gas discharge chamber; and directing the released mixed gas to accommodate the hydrogen oxidation chamber. A reaction vessel. 14. The method of clause 13, 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 comprises sensing the concentration of water in the measurement vessel. the concentration of water in the new gas mixture. 15. The method of clause 13, wherein sensing the concentration of water in the new gas mixture includes exposing a sensor in the measurement vessel to the new gas mixture. 16. The method of clause 1, further comprising discharging the new gas mixture from the measuring container after estimating the concentration of fluorine in the mixed gas portion. 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 the portion of the mixed gas with another material. 18. The method of clause 1, wherein reacting the mixed gas portion with the hydroxide to form the new gas mixture including water includes forming an inorganic fluoride compound plus water. 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 has elapsed after the reaction has begun. concentration. 21. The method of clause 1, wherein the mixed gas portion is a vent gas and reacting the mixed gas portion with the hydroxide to form the new gas mixture including water includes removing fluorine from the vent gas. 22. The method of clause 1, wherein estimating the concentration of fluorine in the mixed gas portion based on the sensed concentration of water includes: based solely on the sensed concentration of water and fluorine in the mixed gas portion The chemical reaction with the hydroxide is estimated. 23. The method of clause 1, wherein the concentration of fluorine in the mixed gas portion is about 500 to 2000 parts per million. 24. The method of clause 1, wherein the reaction of the fluorine and the hydroxide in the mixed gas portion forming the new gas mixture including water is stable. 25. The method of clause 1, wherein reacting the fluorine and the hydroxide in the mixed gas portion to form the new gas mixture including water includes: performing a reaction that is linear and provides the mixed gas portion There is a direct correlation between the concentration of fluorine in the new gas mixture and the concentration of the water in the new gas mixture. 26. The method of clause 1, further comprising sensing a concentration of oxygen in the new gas mixture, wherein estimating the concentration of fluorine in the mixed gas portion is also based on the sensed concentration of oxygen. 27. A method comprising: performing a first gas update by adding a first gas mixture from a set of gas suppliers to a gas discharge chamber; removing at least a portion of a mixed gas from the gas discharge chamber after the first gas refresh, wherein the mixed gas includes fluorine; reacting the fluorine in the removed portion of the mixed gas with a reactant to form a new gas mixture including oxygen and water; sensing a concentration of water in the new gas mixture; Estimating a concentration of fluorine in the removed portion of the mixed gas based on the sensed concentration of water; Adjust the relative concentration of fluorine in a second gas mixture from the set of gas suppliers based on the estimated concentration of fluorine in the removed portion of the mixed gas; and A second gas update is performed by adding an adjusted second gas mixture from the gas suppliers to the gas discharge chamber. 28. The method of clause 27, wherein the reactant comprises a hydroxide. 29. The method of clause 27, wherein the mixed gas in the gas discharge chamber includes an excimer laser gas including at least a mixture of a gain medium and a buffer gas. 30. The method of clause 27, wherein estimating the concentration of fluorine in the removed mixed gas portion based on the sensed concentration of water includes: without measuring the fluorine in the removed mixed gas portion. The fluorine concentration in the removed mixed gas portion is estimated given the fluorine concentration. 31. A device comprising A detection device fluidly connected to each gas discharge chamber of an excimer gas discharge system, wherein each detection device includes: A container defining a reaction cavity containing a hydroxide and fluidly connected to the gas discharge chamber for receiving a mixed gas including fluorine from the gas discharge chamber in the reaction cavity, the container such that A reaction between the fluorine and the hydroxide of the received mixed gas can form a new gas mixture including oxygen and water; and a water sensor configured to be fluidly connected to the new gas mixture and, when fluidly connected to the new gas mixture, sense an amount of water within the new gas mixture; and A control system connected to the detection device, the control system configured to: receiving an output from the water sensor and estimating a concentration of fluorine in the mixed gas received from the gas discharge chamber; determine whether a concentration of fluorine in a gas mixture from a gas supply system of a gas maintenance system should be adjusted based on the estimated concentration of fluorine in the gas mixture; and Send a signal to the gas maintenance system, instructing the gas maintenance system to adjust the gas mixture supplied from the gas supply system of the gas maintenance system to the gas discharge chamber during a gas update period of the gas discharge chamber The relative concentration of fluorine. 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 including an excimer laser gas, the excimer laser gas including a gain Medium and fluorine. 33. Equipment as specified in item 31, wherein: 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; and The water sensor is configured to sense an amount of water in the new gas mixture in the measurement cavity. 34. The equipment of clause 31, wherein the concentration of fluorine in the removed portion of the mixed gas is about 500 to 2000 parts per million. 35. The device of clause 31, wherein the excimer gas discharge system includes a plurality of gas discharge chambers, and the detection device is fluidly connected to each of the plurality of gas discharge chambers, wherein The detection device includes a plurality of containers, each container defining a reaction cavity containing the hydroxide, and each container is fluidly connected to one of the gas discharge chambers and the detection device includes a plurality of Water sensors, each oxygen sensor is associated with a container. 36. The device of clause 31, wherein the excimer gas discharge system includes a plurality of gas discharge chambers, and the detection device is fluidly connected to each of the plurality of gas discharge chambers, wherein The detection device includes a plurality of containers, each container defining a reaction cavity containing the hydroxide, and each container is fluidly connected to one of the gas discharge chambers and the detection device includes and all A single water sensor that is fluidly connected to the containers.

Other implementations are within the scope of the following patent applications.

100:Equipment 105:Detection equipment 107: Gas mixture 110: Chamber 115:Water sensor 116: Sensing equipment 117: Oxygen sensor 120:Gas maintenance system 127: Casing system 130:Controller 135: Reaction vessel 137: Casing 140: Reaction cavity 145:Hydroxide 150:Mixed gas 155:New gas mixture 170: Measuring container 175: Measure the cavity 177: Casing 200:Light source 207: Gas mixture 210:Gas discharge chamber 211:Beam 222:Light lithography equipment 225: Excimer gas discharge system 230:Energy source 290:Control system 300:Equipment 305:Detection equipment 330:Controller 360:Fluorine sensor 365:Flow control device 370: Measuring container 375: Measure the cavity 400:Equipment 405:Detection equipment 470:Buffer container 500:Equipment 505:Detection equipment 507_1,507_2…507_i: Gas mixture 510: Chamber 510_1,510_2…510_i: Chamber 516: Sensing equipment 516_1,516_2…516_i: Sensing device 520:Gas maintenance system 527: Main casing system 527_1,527_3…527_i: Casing system 530:Controller 535_1,535_2…535_i: Reaction vessel 537_1,537_2…537_i: Casing 545_1,545_2…545_i:hydroxide 550_1,550_2…550_i: mixed gas 555_1,555_2…555_i: New gas mixture 600:DUV light source 601:First stage 602: Second stage 605:Detection equipment 606:Beam 607_1: Gas mixture 607_2: Gas mixture 610_1:MO gas discharge chamber 610_2:PA gas discharge chamber 620:Gas maintenance system 625:Gas discharge system 630:Controller 630_1: Slender electrode 630_2: Slender electrode 651A:Gas source 651B:Gas source 651C:Gas source 652:Valve system 653:Valve controller 680:Spectral Feature Selection System 681:Output coupler 682:Return beam 683: Beam coupling equipment 689:Gas dumping 690:Control system 700:Memory 705:Input device 710:Output device 715: Processor 720:Computer program products 730:Controller 731:Gas maintenance module 732:Micro shadow module 790:Control system 800:Equipment 804:Fluorine scrubber 805:Detection equipment 807: Gas mixture 820:Gas maintenance system 835:Fluorine scrubber 845:Hydroxide 820:Gas maintenance system 851A: Triple gas source 851B: Double gas source 852:Valve system 870:Buffer 891:Valve 900:Program 905:Step 910: Steps 915: Steps 920: Steps 1000:Program 1005: Steps 1010: Steps 1100:Program 1112: Steps

1 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;

Figure 2 is a block diagram of the apparatus of Figure 1 implemented as part of a deep ultraviolet (DUV) light source that generates a beam directed to the photolithography apparatus;

Figure 3 is a block diagram of an implementation of the detection device of the device of Figure 1, wherein the detection device includes a fluorine sensor;

Figure 4 is a block diagram of an implementation of the device of Figure 1, wherein the detection device includes a buffer container;

Figure 5 is a block diagram of an implementation of the apparatus of Figure 1, wherein the detection apparatus includes a plurality of reaction vessels, each reaction vessel being associated with one of a plurality of chambers;

Figure 6 is a block diagram of an implementation of the apparatus of Figure 2 showing details of an exemplary DUV light source;

Figure 7 is a block diagram of an implementation of a control system for a portion of the DUV light source shown in Figure 2 or 6;

Figure 8 is a block diagram of another implementation of the equipment of Figure 1, wherein the equipment is implemented in conjunction with a fluorine scrubber;

Figure 9 is a flow chart of a process performed by a detection device for detecting the concentration of fluorine in a gas mixture in a chamber;

Figure 10 is a flowchart of the process performed by the device once the fluorine concentration is estimated and after completion of the process of Figure 9; and

FIG. 11 is a flow chart of a process by a detection device for estimating the concentration of fluorine in a gas mixture in a chamber instead of the process of FIG. 9 .

107: Gas mixture

110: Chamber

115:Water sensor

116: Sensing equipment

117: Oxygen sensor

120:Gas maintenance system

127: Casing system

130:Controller

135: Reaction vessel

137: Casing

140: Reaction cavity

145:Hydroxide

150:Mixed gas

155:New gas mixture

170: Measuring container

175: Measure the cavity

177: Casing

400:Equipment

405:Detection equipment

470:Buffer container

Claims (14)

A device for gas detection, which includes A detection device fluidly connected to at least one gas discharge chamber of an excimer gas discharge system, the detection device comprising: A container defining a reaction cavity containing a hydroxide and fluidly connected to the gas discharge chamber for receiving a mixed gas including fluorine from the gas discharge chamber in the reaction cavity, the container such that A reaction between the fluorine and the hydroxide of the received mixed gas can form a new gas mixture including oxygen and water; and a water sensor fluidly connected to the new gas mixture and adapted to sense an amount of water within the new gas mixture; and A control system configured to estimate a concentration of fluorine in the mixed gas received from the gas discharge chamber based on the amount of water in the new gas mixture sensed by the water sensor. The device of claim 1, wherein each gas discharge chamber of the excimer gas discharge system contains an energy source and contains a gas mixture including an excimer laser gas, the excimer laser gas includes a gain medium and fluorine. Such as the equipment of request item 1, where: 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; and The water sensor is configured to sense an amount of water in the new gas mixture in the measurement cavity. The device of claim 1, wherein the excimer gas discharge system includes a plurality of the gas discharge chambers, and the detection device is fluidly connected to each of the plurality of gas discharge chambers, wherein the detection device includes a plurality of containers, each container defines a reaction cavity containing the hydroxide, and each container is fluidly connected to one of the gas discharge chambers and the detection device includes a plurality of water sensors, each oxygen sensor is associated with a container. The device of claim 1, wherein the excimer gas discharge system includes a plurality of the gas discharge chambers, and the detection device is fluidly connected to each of the plurality of gas discharge chambers, Wherein the detection device includes a plurality of containers, each container defines a reaction cavity containing the hydroxide, and each container is fluidly connected to one of the gas discharge chambers and the detection device includes and A single water sensor with all such containers fluidly connected. The device of claim 1, wherein the mixed gas portion is an exhaust gas of one of the gas discharge chambers and forms the new gas mixture including oxygen and water between the fluorine and the hydroxide of the received mixed gas. The reaction involves removing fluorine from the exhaust gas. The equipment of claim 6, wherein the concentration of fluorine in the removed portion of the mixed gas is about 500 to 2000 parts per million. The device of claim 1, wherein the hydroxide includes an alkaline earth metal hydroxide. Such as the equipment of claim 1, wherein the hydroxide lacks an alkali metal and carbon. The device of claim 1, wherein the mixed gas is an excimer laser gas including at least a mixture of a gain medium and a buffer gas. The device of claim 1, wherein the hydroxide includes calcium hydroxide, and the inorganic fluoride compound includes calcium fluoride. Such as the equipment of claim 1, wherein the control system is further configured to: determine whether a concentration of fluorine in a gas mixture from a gas supply system of a gas maintenance system should be adjusted based on the estimated concentration of fluorine in the gas mixture; and Send a signal to the gas maintenance system instructing the gas maintenance system during a gas refresh of the gas discharge chamber by filling the gas discharge chamber with a gain medium and a mixture of buffer gas and fluorine 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 is adjusted. The device of claim 12, wherein a mixture of a gain medium and a buffer gas and fluorine includes the gain medium including a rare gas and a halogen and the buffer gas including an inert gas. The device of claim 13, wherein the rare gas includes argon, krypton or xenon; the halogen includes fluorine; and the inert gas includes helium or neon.