TWI770568B - 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 Sources

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 one or more noble gases such as argon, krypton or xenon in combination with reactive gases such as fluorine or chlorine. The name excimer light source is derived from the fact that under appropriate conditions of electrical stimulation (supplied energy) and high pressure (of gas mixtures) pseudo-molecules called excimers are generated, which exist only in an energized state and produce in the ultraviolet range Amplify light.

Excimer light sources generate light beams with wavelengths in the deep ultraviolet (DUV) range, and this light beam is used to pattern semiconductor substrates (or wafers) in photolithography equipment. The 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 from a gas discharge chamber at least a portion of a mixed gas, the mixed gas including fluorine; reacting the fluorine in the mixed gas portion with a hydroxide to form a mixture comprising oxygen and a new gas mixture of water; sensing a concentration of water within the new gas mixture; and estimating a concentration of fluorine within the gas mixture portion based on the sensed concentration of water.

Implementations may include one or more of the following features. For example, the hydroxide can 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 the estimated concentration of fluorine in the mixed gas portion; and by supplying the adjusted gas mixture from the gas supplies A gas discharger is added to the gas discharge chamber to perform a gas refresh. The gas refresh can be performed by filling the gas discharge chamber with a mixture of a gain medium and a buffer gas and fluorine. The gas discharge chamber can be filled with the mixture of the gain medium and the buffer gas by filling the gas discharge chamber with a gain medium comprising a noble gas and a halogen, and one comprising an inert gas buffer gas. The noble 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 can be filled with the mixture of the gain medium and the buffer gas and fluorine by adding the gain medium and the mixture of the buffer gas and fluorine to an existing one in the gas discharge chamber mixed gas; or at least replace an existing mixed gas in the gas discharge chamber with the mixture of the gain medium and the buffer gas and fluorine. The gas refresh may be performed by performing one or more of a gas refill scheme or a gas injection scheme.

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

The gas refresh may be performed by performing one or more of a gas refill scheme or a gas injection scheme.

The portion of the mixed gas can be received from the gas discharge chamber by venting the mixed gas from the gas discharge chamber and directing the vented 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 measuring vessel, wherein sensing the concentration of water in the new gas mixture includes sensing the new gas mixture within the measuring vessel the concentration of the water within. The concentration of water in the new gas mixture can be sensed by exposing a sensor in the measuring 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 mixed gas portion with another material.

The mixed gas portion can 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 can 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 begins.

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

The amount of water in the mixed gas portion can be estimated based on the sensed concentration of water by estimating only based on the sensed concentration of water and the chemical reaction between the fluorine and the hydroxide in the mixed gas 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 that forms 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 A direct correlation between the concentration of the water in the mixture.

The method may also include sensing a concentration of oxygen within the new gas mixture, and estimating the concentration of fluorine within the portion of the mixed gas may additionally 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 supplies to a gas discharge chamber; removing after the first gas refresh at least a portion of a mixed gas of the gas discharge chamber, the mixed gas including fluorine; reacting the fluorine of 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; a concentration of fluorine in the removed mixed gas portion estimated based on the sensed concentration of water; adjusted based on the estimated concentration of fluorine in the removed mixed gas a relative concentration of fluorine in a second gas mixture from a second gas mixture of the set of gas suppliers; and a second gas update by adding the 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 can 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 removed mixed gas portion.

In other general aspects, an apparatus includes: a detection apparatus fluidly connected to each gas discharge chamber of an excimer gas discharge system; and a control system connected to the detection apparatus. Each detection apparatus includes: a vessel defined to hold 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 vessel enables a reaction between the fluorine and the hydroxide of the received mixed gas to form a new gas mixture comprising 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 output from the water sensor and estimate a concentration of fluorine in the mixed gas received from the gas discharge chamber; determine whether to be based on the experience of the 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 indicating that the gas maintenance system is 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 refresh.

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

1, apparatus 100 includes 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 gas of diatomic molecules and is represented by its molecular structure _F2 . _The term "fluorine" as used herein thus refers to molecular fluorine F2. _The concentration of fluorine molecules F2 in chamber 110 is in a range that is too high to permit 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 typically saturate at 10 ppm, thus making it impractical to directly measure the concentration of fluorine in chamber 110 using a commercially available fluorine sensor. 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 can be utilized by sensing device 116 . Commercially available sensor 115 detects and measures. The detection device 105 may calculate or estimate how much fluorine was present before the chemical reaction was started 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, with the concentration of fluorine before starting the chemical reaction and the concentration of water at the end of the chemical reaction There is a direct correlation. Alternatively, the detection apparatus 105 may assume that the conversion of fluorine is complete (and thus, 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 gas from the suppliers is diverted into or out of the chamber via the cannula 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 the chemical reaction begins to estimate the amount of fluorine in the gas mixture 107 . The controller 130 uses this information to determine whether the concentration of fluorine in the gas mixture 107 needs to be adjusted. The controller 130 thus determines, based on this determination, how to adjust the relative amount of gas to be diverted into or out of the chamber 110 in the supply of the gas maintenance system 120 . The controller 130 sends a signal to the gas maintenance system 120 instructing it to adjust the relative concentration of fluorine in the gas mixture 107 during the gas refresh of the chamber 110 .

The detection apparatus 105 includes a reaction vessel 135 defining a reaction cavity 140 containing hydroxide Σ(-OH) 145, where Σ is a metal. The reaction cavity 140 is fluidly connected to the chamber 110 via the sleeve 137 to receive the mixed gas 150 including fluorine from the chamber 110 . Although not shown, one or more fluid control devices, such as valves, may be placed in the sleeve 137 to control the timing of when the mixed gas 150 is directed to the reaction cavity 140 and to control the flow of the mixed gas 150 into the reaction vessel 135 rate. In this way, the reaction cavity 140 enables the chemical reaction between the fluorine of the received mixed gas 150 and the hydroxide 145 to form a new gas mixture 155 . The interior of the reaction vessel 135 that defines the reaction cavity 140 should be made of non-reactive materials so as not to interfere or alter the chemical reaction between the fluorine of the received mixed gas 150 and the hydroxide 145 . For example, the interior of the reaction vessel 135 may be made of a non-reactive metal such as stainless steel or Monel metal.

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

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

In some implementations, the water sensor 115 can be a hygrometer that measures the amount or humidity of water vapor in the cavity 175 . Tools that measure humidity typically also measure temperature, pressure, mass, or even mechanical or electrical changes in moisture-absorbing substances, since these factors can also affect humidity. By 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 known as the dew point), the complete vapor saturation point of a substance. A hygrometer can be a device that detects and measures changes in capacitance or resistance of substances to determine humidity. A hygrometer can be a resistive hygrometer that measures changes in the ability of a substance to retain an electrostatic charge. A hygrometer can be a capacitor-based hygrometer that measures changes in the ability of a substance to transmit electricity.

In some implementations, although not required, the sensing device 116 includes a second sensor 117 that can sense oxygen in the fresh gas mixture 155 in the range of 200 to 1000 parts per million (ppm) oxygen 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 cells made of high-purity, high-density, and stable zirconia ceramics. The zirconium dioxide sensor produces a voltage signal indicative of the oxygen concentration of the fresh gas mixture 155 . In addition, the output of the zirconia sensor is analyzed (eg, converted and linearized) by a high speed microprocessor within the oxygen sensor 117 to provide a direct digital readout for use by the controller 130. A conventional zirconium dioxide cell includes a zirconium dioxide ceramic tube with porous platinum electrodes electroplated on its inner and outer surfaces. When the zirconium dioxide sensor is heated above a certain temperature (eg, 600 C or 1112° F), it becomes an oxygen ion conducting electrolyte. The electrodes provide catalytic surfaces 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, oxygen ions lose electrons and are released from the surface as oxygen molecules. When the oxygen concentration on each side of the zirconia sensor is different, oxygen ions migrate from the high concentration side to the low concentration side. This flow of ions 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 for direct readout by the controller 130.

The fluorine in the mixed gas 150 reacts with the hydroxide 145 because the chemical reaction between the fluorine and the hydroxide is a stoichiometrically simple chemical reaction that is easy to implement and control. Furthermore, the controlled stoichiometric ratio of chemical reactions is fixed. In addition, the chemical reaction between fluorine and hydroxide is a stable chemical reaction. A chemical reaction may be stable if the chemical reaction 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. A suitable chemical reaction between fluorine and hydroxide 145 in a stable and controlled stoichiometric ratio of mixed gas 150 is discussed next.

In some implementations, the hydroxide 145 is in particulate, solid, powder form. Furthermore, the hydroxide 145 in particulate form can be tightly packed into the reaction vessel 135 (which can be a tube) so that there is no movement of the particles in the powder of the hydroxide 145 . Areas or volumes outside the powder of the hydroxide 145 and in the space within the reaction vessel 135 are considered pores, and by using the hydroxide 145 in particulate form, it is possible to ensure that there is a large surface area to allow the hydroxide 145 to interact with each other. Sufficient chemical reaction between fluorines. 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.

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

The 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 ] (Σ is Ca in this example). Calcium hydroxide is in particulate and solid form with sufficient pores to provide sufficient surface area to allow chemical reaction with fluorine gas. The spaces between the calcium hydroxide particles are large enough to allow fluorine gas to flow into the calcium hydroxide to effect the chemical reaction. For example, calcium hydroxide may be in the form of particles packed in a row and the level of packing depends on the level of fluorine concentration in the mixed gas 150 to be analyzed. The mixed gas 150 is passed (eg, flowed) through or across the hydroxide 145 to effect a chemical reaction between the fluorine and the calcium hydroxide.

In the presence of fluorine gas (F ₂ ) 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, two molecules of an inorganic fluoride compound (calcium fluoride or CaF ₂ ), oxygen (O ₂ ) one molecule 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 to the chemical reaction, one _mole of _H2O is output from the chemical reaction. Therefore, if 2 moles of fluorine F ₂ are input into a chemical reaction, 2 moles of water H ₂ O are released after the chemical reaction. This water is detected by the water sensor 115 . Thus, for example, since the controller 130 (which accesses data from 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 0.6 moles of fluorine is present in the gas mixture 107 . In other implementations, the detection apparatus 105 may assume that the conversion of fluorine is complete (and thus, no residual molecular fluorine F2 is present in the gas after the chemical reaction ₎ . This assumption may be a valid assumption, for example, if sufficient time has elapsed after starting the chemical reaction.

In this example, if sensing device 116 also includes oxygen sensor 117 , the measurement of the concentration of oxygen from oxygen sensor 117 may be used in conjunction with the measurement of water from 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 the 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 the sensor 117 detects 0.3 moles of oxygen, the controller determines that the gas mixture 107 is in the 0.6 moles of fluorine is present. Controller 130 can 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, a more accurate determination of fluorine can be made using two data sets. Additional calibrations and corrections may also be used by the controller (eg to account for fluorine, oxygen or water consumption or inefficiency detection), as will be understood by those skilled in the art.

In some implementations, the reaction between hydroxide 145 and fluorine in mixed gas 150 occurs under one or more specifically designed conditions. For example, the reaction between hydroxide 145 and fluorine in mixed gas 150 can occur in the presence of one or more catalysts that alter the rate of the chemical reaction but are chemically indifferent when the chemical reaction is terminated. Substances that change. 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.

Referring to Figure 2, apparatus 100 may be implemented, for example, within an ultraviolet (UV) or deep ultraviolet (DUV) light source 200 that generates a light beam 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 the various elements of the light source 200 to enable the generation of the light beam 211 . Although the control system 290 is shown as a single piece, it can be made from a plurality of subassemblies, any one or more of which can be removed from other subassemblies or local to components within the 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 produces the light 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 elements such as optics, Metrology and electromechanical elements) are in fluid communication for controlling the aspect of the light beam 211, such other elements are not shown in FIG. 2 . Furthermore, only the components of the light source 200 associated with the apparatus 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.

The gas discharge chamber 210 houses the energy source 230 and contains the gas mixture 207 . Energy source 230 provides a source of energy to gas mixture 207 ; in particular, energy source 230 provides sufficient energy to gas mixture 207 to cause population inversion to achieve gain via stimulated emission within chamber 210. In some examples, energy source 230 is a discharge provided by a pair of electrodes placed within gas discharge chamber 210 . In other examples, the energy source 230 is an optical pump source.

The gas mixture 207 includes a gain medium, which includes noble gases and halogens, such as fluorine. During operation of the DUV light source 200, the fluorine of the gas mixture 207 within the gas discharge chamber 210, which provides a gain medium for light amplification, is consumed, and over time, this reduces the amount of light amplification and thus changes produced by the light source 200. The characteristics of the beam 211. The photolithography apparatus 222 attempts to maintain the concentration of fluorine within the gas mixture 207 in the gas discharge chamber 210 within a certain tolerance compared to the concentration of fluorine set under the initial gas refill procedure. Thus, additional fluorine is added to the gas discharge chamber 210 at a conventional pace and under the control of the gas maintenance system 120 . Fluorine consumption varies from gas discharge chamber to gas discharge chamber, 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 to determine the concentration of fluorine remaining in the gas discharge chamber 210, and thus, in the overall scheme of determining the amount of fluorine pushed or injected into the gas discharge chamber 210.

As mentioned, the gas mixture 207 includes a gain medium, which includes noble gases and fluorine. The gas mixture 207 may include other gases, such as buffer gases. The gain medium is the laser active entity within the gas mixture 207, and the gain medium may be composed of individual atoms, molecules or pseudo-molecules. Thus, population inversion is produced in the gain medium via stimulated emission by pumping the gas mixture 207 (and thus the gain medium) with a discharge from the energy source 230 . As mentioned above, the gain medium typically includes noble gases and halogens, while the buffer gas typically 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 (lean or noble gases), and thus, it is assumed that the only chemical reaction that takes place between the mixed gas 150 and the hydroxide 145 is the fluorine in the mixed gas 150 and the Reaction between hydroxides 145.

Referring again to FIG. 1 , gas maintenance system 120 is a gas management system for adjusting properties such as relative concentrations or pressures of components within gas mixture 107 or 207 .

3, in some implementations where the sensing device includes an oxygen sensor 117 used in conjunction with the water sensor 115 to determine or estimate the concentration of fluorine in the gas mixture 107, the device is device 300 and 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 above a concentration of fluorine that 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 falls below the lower limit. For example, the fluorine sensor 360 may be saturated at a 10 ppm concentration, but it may have a minimum detection threshold of about 0.05 ppm, and the concentration of fluorine in the fresh gas mixture 155 may drop below 0.1 ppm The detection of fluorine in the new gas mixture 155 is then started.

Controller 130 is configured as controller 330 that receives output from fluorine sensor 360 . Controller 330 includes a module that interacts with flow control device 365 along the lines that deliver 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.

The controller 330 sends a signal to the flow control device 365 to enable the fresh gas only when the fluorine concentration in the fresh gas mixture 155, as determined from the output of the fluorine sensor 360, falls below a lower limit (eg, 0.1 ppm) The mixture 155 can flow to the oxygen sensor 117 . In this way, the oxygen sensor 117 is only exposed to the fresh gas mixture 155 if the concentration of fluorine falls 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 value of the oxygen sensor 117 . Therefore, at the concentration of fluorine higher than the lower limit, damage to the oxygen sensor 117 may be caused. The lower limit value may be a value determined based on the error threshold value of the oxygen sensor 117 . Therefore, the measurement error may affect the accuracy of the oxygen sensor 117 at a concentration of fluorine higher than the lower limit.

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

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

In one example, the concentration of fluorine within chamber 110 is about 1000 ppm, the volume of chamber 110 is 36 liters (L), and the pressure within chamber 110 is 200 to 400 kilopascals (kPa). The inner cavity of the buffer vessel 470 has a volume of about 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 about 200 to 400 kPa, a water concentration of 1000 ppm, and an oxygen concentration of about 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 can then be emptied in a controlled manner .

As mentioned above with reference to FIG. 1 , apparatus 100 is configured to measure or estimate the concentration of fluorine in gas mixture 107 in chamber 110 . In some implementations, as shown in FIG. 5, apparatus 100 is designed as apparatus 500 and detection apparatus 105 is designed as detection apparatus 505, which is configured to measure or estimate the respective chamber 510_1 , the concentration of fluorine in the gas mixtures 507_1, 507_2...507_i in 510_2...510_i, where i is an integer greater than 1. In the detection device 505, there are separate or dedicated sensing devices 516_1, 516_2...516_i associated with the respective chambers 510_1, 510_2...510_i. In this way, 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 comprising a gas supply system fluidly connected to each of the chambers 510_1 , 510_2 ... 510_i via a respective casing system 527_1, 527_3... The 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 supplies and a control unit for controlling which of the gas from the supplies is diverted into and out of the respective chambers 510_1 , 510_2 . . . 510_i by the main casing system 527 . The detection apparatus 505 includes respective reaction vessels 535_1, 535_2...535_i receiving mixed gases 550_1, 550_2...550_i (which include fluorine) from respective chambers 510_1, 510_2...510_i via respective sleeves 537_1, 537_2...537_i. The new gas mixtures 555_1, 555_2...555_i formed by the chemical reaction between the fluorine of the mixed gases 550_1, 550_2...550_i received in the respective reaction vessels 535_1, 535_2...535_i and the hydroxides 545_1, 545_2...545_i are then directed to respective sensing devices 516_1 , 516_2 . . . 516_i.

The detection device 505 also includes a controller 530 connected to the gas maintenance system 520 and to each of the sensing devices 516_1 , 516_2 . . . 516_i. Like controller 530, controller 530 receives outputs from sensing devices 516_1, 516_2...516_i and calculates or estimates how much fluorine is present in reaction vessels 535_1, 535_2...535_i before chemical reactions begin 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 . ducts to prevent crosstalk between measurements made by the sensing device 516 for each of the chambers 510_1 , 510_2 . . . 510_i. Furthermore, a single sensing device 516 design can function if only one chamber 510 is gas exchanged at a time, and thus the controller 530 can measure fluorine in a single chamber 510 at any one time.

6, an exemplary DUV light source 600 is shown incorporating a detection device 605, such as detection device 105, and a controller 630, such as controller 130 of Figures 1, 3, 4, or 5. DUV light source 600 includes an excimer gas discharge system 625 designed for dual stage pulse output. 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 driven from the first stage Stage 601 receives the power amplifier (PA) of light 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 as its energy source two elongated electrodes 630_2 that provide a source of energy to the gas mixture 607_2 within 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 gas mixture 607_1 including gain medium in which amplification occurs, and MO 601 also includes optical feedback mechanisms such as spectral feature selection system 680 formed on one side of MO gas discharge chamber 610_1 and MO gas Optical resonator between output couplers 681 on the second side of discharge chamber 610_1.

PA gas discharge chamber 610_2 contains gas mixture 607_2 including gain medium 607_2, in which amplification occurs when seed beam 606 from MO 601 is sprinkled. If the PA 602 is designed as a regenerative ring resonator, it is described as a power ring amplifier (PRA), and in this case, sufficient optical feedback from the ring design can be provided. 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, with the input into the ring amplifier at beam coupling device 683 and out of the ring amplifier The output intersects.

MO 601 enables fine tuning of spectral parameters, such as center wavelength and bandwidth, at relatively low output pulse energy (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 of suitable gases for generating amplified beams of approximately the desired wavelength and bandwidth, such as seed beam 606 and output beam 211 . combination. For example, the gas mixtures 607_1, 607_2 may include argon fluoride (ArF), which emits light at a wavelength of about 193 nanometers (nm), or krypton fluoride (KrF), which emits light at a wavelength of about 248 nm.

The detection apparatus 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 cylinders or tanks) and valve system 652 . One or more gas sources 651A, 651B, 651C, etc. are connected to MO gas discharge chamber 610_1 and PA gas discharge chamber 610_2 through a set of valves within valve system 652. In this way, the gas can 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, the gas maintenance system 620 may also include one or more other components, such as flow restrictors, exhaust 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, the 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, 610_2 is argon fluoride (ArF), the gas source 651A contains halogen fluorine, noble gas argon, and one or more other rare gases, such as buffer gas (which may be an inert gas such as neon) gas mixture. Such a mixture within gas source 651A may be referred to as a triple gas, since it contains three types of gases. In this example, another gas source 651B may contain a gas mixture that includes argon and one or more other gases but no fluorine. Such a mixture in the gas source 651B may be referred to as a duplex 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 specific gas sources 651A, 651B, 651C, etc. to in the gas discharge chambers 610_1 and 610_2. The gas refresh can be a refilling of the gas mixture 607 within the gas discharge chamber, wherein at least the existing gas mixture in the gas discharge chamber is replaced with a mixture of gain medium and buffer gas and fluorine. Gas refresh can 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 additionally, valve controller 653 may send one or more signals to valve system 652 to cause valve system 652 to vent gas from discharge chambers 610_1 , 610_2 as necessary, and such vented gas may be vented to a signal denoted as 689 Gas Dumping. In some implementations, it is possible for the evolved gas to instead be fed into detection device 605, as shown in FIG.

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

Multiple gas sources 651A, 651B, 651C, etc. are required because the fluorine in gas source 651A is at a specific partial pressure that is generally higher than that required for laser operation. To add fluorine to the gas chamber 610_1 or 610_2 at the desired lower partial pressure, the gas in the gas source 651A can be diluted, and the halogen-free gas in the 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 fill 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).

When refilling the gas discharge chamber 610_1 or 610_2, for example by purging the gas discharge chamber 610_1 or 610_2 (by venting the gas mixture to the gas dump 689) and then refilling the gas discharge chamber with fresh gas mixture The chamber 610_1 or 610_2 replaces all the gas in the gas discharge chamber 610_1 or 610_2. Refilling is performed to obtain a specific pressure and concentration of fluorine in the gas discharge chamber 610_1 or 610_2. When the injection scheme is performed on the gas discharge chamber 610_1 or 610_2, the gas discharge chamber is not emptied or only a small amount is discharged before the gas mixture is injected into the gas discharge chamber. In both gas updates, detection device 605 (which is similar in design to detection device 105) may receive some of the gas mixture emitted as gas mixture 150 for analysis within detection device 605 to determine the gas discharge chamber The concentration of fluorine in the chamber 610_1 or 610_2 in order to determine how to perform the gas refresh.

The valve controller 653 interfaces with the detection device 605 (and in particular with the controller 130 in the detection device 605). Additionally, valve controller 653 may interface with other control modules and sub-assemblies that are part of control system 690, which is discussed next.

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 block diagram. Details are provided regarding the control system 790 regarding aspects of the detection apparatus 105/605 described herein and regarding 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 disks and removable disks; magneto-optical disks; and CD-ROM disks. The control system 790 may also include one or more input devices 705 (such as a keyboard, touch screen, microphone, mouse, handheld input device, etc.) and one or more output devices 710 (such as a speaker or monitor).

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 may each execute the instructions of the program to perform desired functions by operating on input data and generating appropriate output. In general, processor 715 receives instructions and data from memory 700 . Either of the foregoing may be supplemented by or incorporated in a specially designed ASIC (application specific integrated circuit).

The control system 790 may also include, among other components or modules, the controllers 130 , 330 , 530 of the detection device 105 (represented as block 730 in FIG. 7 ) and interfaced 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 . Additionally, either controller 730/module 731 can access data stored in 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 sources 600, may be wired or wireless of.

Although only a few modules are shown in FIG. 7, it is possible for the control system 790 to include other modules. Additionally, although control system 790 is represented as a block where all components appear to be co-located, it is possible for control system 790 to be composed of components that are physically or temporally distant from each other. 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 commands from a lithography controller of the photolithography apparatus 222, such as commands to measure or estimate the concentration of fluorine in the gas mixture 107 of the chamber 110.

8, in some implementations, apparatus 100 is designed as apparatus 800 and detection apparatus 105 is designed as detection apparatus 805 operating in parallel with a fluorine scrubber 804 in fluid communication with a gas maintenance system 820 . Fluorine scrubber 804 is used in conjunction with gas maintenance system 820 to properly exhaust gas mixture 807 from chamber 110 by chemically reacting fluorine within gas mixture 807 to form a chemical that can be safely disposed of, such as via exhaust .

A portion of the mixed gas 150 of the vent gas maintenance system 820 is directed to a buffer vessel 870 and then to another fluorine scrubber 835 that includes hydroxide 845 . The fluorine in the mixed gas 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 that includes oxygen. The new gas mixture 155 is directed to the sensing device 116 where it is sensed. Controller 130 estimates the oxygen concentration and fluorine concentration within mixed gas 150 and gas mixture 107 and determines how to adjust gas maintenance system 820 for gas refresh. In this example, the gas maintenance system 820 includes a valve system 852 fluidly connected to the triadic gas source 851A and the bicompartmental gas source 851B. Various control valves 891 are placed along the lines to control the flow rate and to control the amount of gas directed through the lines.

Referring to FIG. 9 , a procedure 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 apparatus of FIG. 1, but the procedure 900 is equally applicable to the apparatus described with reference to FIGS. 2-8. Detection device 105 receives a portion of gas mixture 150 including fluorine from gas discharge chamber 110 (905). The fluorine in the mixed gas 150 chemically reacts with the hydroxide 145 to form a new gas mixture 155 that includes water (910). For example, sensor 115 is used to sense the concentration of water in fresh 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 vented from chamber 110 and then directed to detection device 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 negative pressure using a series of valves and vacuum pumps, to push gas mixture 107 out of chamber 110 and to detection device 105 . The amount of gas mixture 150 required in the reaction vessel 135 can be determined based on the needs 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, it is desirable to have accurate readings from the water sensor 115, but it is also desirable to minimize the total airflow so that the hydroxide 145 can have a maximum useful life.

The mixed gas 150 received (905) by the detection device 105 may be the mixed gas 150 exhausted from the chamber 110 toward the fluorine scrubber, and thus the mixed gas 150 can be regarded as 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 that includes oxygen.

Routine 900 may be performed to predict gas refresh, such as gas refill or gas injection. For example, the first gas refresh can 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 procedure 900 can be performed. After procedure 900 is performed, a second gas refresh may then be performed by adding the adjusted second gas mixture to chamber 110 from gas maintenance system 120 . The adjusted second gas mixture has a concentration of fluorine (or amount of fluorine) that can be based on measurements made by process 900 .

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

After chemically reacting the fluorine with hydroxide 145 to form new gas mixture 155 (910), new gas mixture 155 can be transferred from reaction vessel 135 into measurement vessel 170 to enable new gas mixture 155 to be sensed Concentration of water in (915). The concentration of water in the fresh gas mixture 155 can thus be sensed by exposing the sensor 115 within the measurement vessel 170 to the fresh gas mixture 155 (915). The concentration of water in the new gas mixture 155 is sensed (915) without having to dilute the mixed gas 150 with another material.

Furthermore, after the chemical reaction has started (910), it may not be suitable to wait until or only after a predetermined period of time has elapsed to sense the concentration of water in the new gas mixture 155 (915). This will ensure that sufficient fluorine in the mixed gas 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 in the mixed gas 150 and the total volume of the hydroxide 145, it may take several seconds or several minutes to completely convert the fluorine to water.

In some implementations, the chemical reaction (910) system can be performed by passing the mixed gas 150 at a low rate (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 condition, water can be sensed in a continuous manner (915). The concentration of fluorine (920) can be estimated from the integration of the sensed water mass measurement (915) over a period of time or when the sensed water mass measurement (915) has reached a steady state.

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 fluorine in the mixed gas 150 to water.

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

Referring to FIG. 10 , once the fluorine concentration is estimated ( 920 ) and after the procedure 900 is completed, the procedure 1000 is performed by the apparatus 100 . The gas maintenance system 120 receives output from the controller 130 of the 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 a gas refresh (1010) by adding the adjusted gas mixture to the chamber 110 through the cannula system 127 until the pressure within the chamber 110 reaches the desired level. Gas updates can be accomplished and tracked by monitoring the timing of valves within the gas maintenance system 120 .

For example, referring to Figure 2, gas refresh (1010) may include filling the gas discharge chamber 210 with a mixture of a gain medium and a buffer gas and fluorine, wherein 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) with respect to when the fluorine concentration estimation (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, an adjustment ( 1005 ) and a gas update ( 1010 ) may be performed immediately after the estimation ( 900 ). In some implementations, it is possible to delay the adjustment of the fluorine (1005) until it is determined that the concentration of fluorine in the 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 apparatus 100 must perform a gas refresh for other reasons, it is possible to perform a gas refresh without the need to increase the fluorine in the gas mixture 107 level is the target.

Referring to FIG. 11 , in some implementations, the detection device 305 performs the process 1100 instead of the process 900 to estimate the concentration of fluorine in the mixed gas 150 . Process 1100 is similar to process 900 and includes the steps of: receiving a portion of mixed gas 150 including fluorine from gas discharge chamber 110 (905); and chemically reacting the fluorine in mixed gas 150 with hydroxide 145 to form a mixture comprising Fresh gas mixture of water and oxygen 155 (910). Routine 1100 determines whether the concentration of fluorine in new gas mixture 155 has dropped 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 forward only if the concentration of fluorine in new gas mixture 155 has dropped below The lower limit value (1112) instructs the sensing device 116 to sense both the water concentration (via sensor 115) and the oxygen concentration (via sensor 117) in the new gas mixture 155 (915). As before, 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 is a value determined based on the damage threshold of the sensor 115 . In other implementations, the lower limit is a value determined based on the error threshold of the sensor 115 . For example, the lower limit may be 0.1 ppm.

Other aspects of the invention are set forth in the numbered clauses below. 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 comprising 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 comprises an alkaline earth metal hydroxide. 3. The method of clause 1, wherein the hydroxide lacks an alkali metal and carbon. 4. The method of clause 1, wherein the mixed gas is an excimer laser gas comprising at least a mixture of a gain medium and a buffer gas. 5. The method of clause 1, further comprising: Adjusting a relative concentration of fluorine in a gas mixture from a set of gas suppliers based on the estimated concentration of fluorine in the mixed gas portion; and A gas refresh is performed by adding a conditioned gas mixture from the gas supplies to the gas discharge chamber. 6. The method of clause 5, wherein performing the gas refresh comprises filling the gas discharge chamber with a mixture of a gain medium and a 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 comprises: filling the gas discharge chamber with a gain medium, the gain medium comprising a noble gas and a halogen , and a buffer gas including an inert gas. 8. The method of clause 7, wherein the noble gas comprises argon, krypton, or xenon; the halogen comprises fluorine; and the noble gas comprises 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 comprises: adding the mixture of the gain medium and the buffer gas and fluorine to an existing gas mixture in the gas discharge chamber; or At least one existing mixed gas in the gas discharge chamber is replaced with the mixture of the gain medium and the buffer gas and fluorine. 10. The method of clause 5, wherein performing the gas refresh comprises performing one or more of a gas refill scheme or a gas injection scheme. 11. The method of clause 1, wherein receiving at least the portion of the mixed gas from the gas discharge chamber comprises: receiving the mixed gas portion prior to performing a gas refresh of the gas discharge chamber, wherein the gas refresh comprises converting A gas mixture is added to the gas discharge chamber from a set of gas suppliers, wherein the gas mixture includes at least some fluorine. 12. The method of clause 11, wherein performing the gas refresh comprises performing one or more of a gas refill scheme or a gas injection scheme. 13. The method of clause 1, wherein receiving at least the portion of the mixed gas from the gas discharge chamber comprises: emitting the mixed gas from the gas discharge chamber; and directing the emitted mixed gas to contain the hydroxide One of the reaction vessels. 14. The method of clause 13, further comprising transferring the new gas mixture from the reaction vessel to a measuring vessel, wherein the sensing the concentration of water in the new gas mixture comprises sensing the measuring 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 comprises exposing a sensor in the measurement vessel to the new gas mixture. 16. The method of clause 1, further comprising venting the new gas mixture from the measurement vessel after the concentration of fluorine in the mixed gas portion has been estimated. 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 the mixed gas portion with the hydroxide to form the new gas mixture comprising water comprises 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 begins concentration. 21. The method of clause 1, wherein the mixed gas portion is an exhaust gas and reacting the mixed gas portion with the hydroxide to form the new gas mixture comprising water comprises removing fluorine from the exhaust 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 comprises: 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 portion of the mixed gas forming the new gas mixture comprising water is stable. 25. The method of clause 1, wherein reacting the fluorine in the mixed gas portion with the hydroxide to form the new gas mixture comprising water comprises: performing a reaction that is linear and provides the mixed gas portion 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 within the new gas mixture, wherein estimating the concentration of fluorine within the mixed gas portion is also based on the sensed concentration of oxygen. 27. A method comprising: performing a first gas refresh by adding a first gas mixture to a gas discharge chamber from a set of gas suppliers; 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 of the removed portion of the mixed gas with a reactant to form a new gas mixture comprising oxygen and water; sensing a concentration of water in the new gas mixture; Estimating a concentration of fluorine within the removed portion of the mixed gas based on the sensed concentration of water; Adjust a relative concentration of fluorine in a second gas mixture from a second gas mixture of the set of gas suppliers based on the estimated concentration of fluorine in the removed portion of the mixed gas; and A second gas refresh is performed by adding a conditioned second gas mixture from the gas supplies 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 comprises an excimer laser gas comprising at least a mixture of a gain medium and a buffer gas. 30. The method of clause 27, wherein estimating the concentration of fluorine within the removed mixed gas portion based on the sensed concentration of water comprises: not measuring the removed mixed gas portion The fluorine concentration in the removed mixed gas portion is estimated with the fluorine concentration. 31. An apparatus comprising A detection device fluidly connected to each gas discharge chamber of an excimer gas discharge system, wherein each detection device includes: a vessel defining a reaction cavity containing a hydroxide and fluidly connected to the gas discharge chamber for receiving a mixed gas including fluorine in the reaction cavity from the gas discharge chamber, the vessel such that A reaction between the fluorine and the hydroxide of the received mixed gas can form a new gas mixture comprising 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 output from the water sensor and estimating a concentration of fluorine in the mixed gas received from the gas discharge chamber; determining 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 mixed gas; and sending a signal to the gas maintenance system instructing the gas maintenance system to adjust the supply of the gas supply system from the gas maintenance system to a gas mixture in the gas discharge chamber during a gas refresh 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 houses an energy source and contains a gas mixture comprising an excimer laser gas comprising a gain medium and fluorine. 33. The apparatus of clause 31, wherein: The detection apparatus 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 apparatus 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 apparatus of clause 31, wherein the excimer gas discharge system comprises a plurality of gas discharge chambers, and the detection device is fluidly connected to each gas discharge chamber of the plurality of gas discharge chambers, wherein The detection apparatus includes a plurality of vessels, each vessel defining a reaction cavity containing the hydroxide, and each vessel is fluidly connected to one of the gas discharge chambers and the detection apparatus includes a plurality of Water sensors, each oxygen sensor is associated with a container. 36. The apparatus of clause 31, wherein the excimer gas discharge system comprises a plurality of gas discharge chambers, and the detection device is fluidly connected to each gas discharge chamber of the plurality of gas discharge chambers, wherein The detection apparatus includes a plurality of vessels, each vessel defining a reaction cavity containing the hydroxide, and each vessel is fluidly connected to one of the gas discharge chambers and the detection apparatus includes and all The containers are fluidly connected to a single water sensor.

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

100: Equipment 105: Detect 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: Measuring cavity 177: Casing 200: light source 207: Gas mixture 210: Gas discharge chamber 211: Beam 222: Light lithography equipment 225: Excimer Gas Discharge Systems 230: Energy Source 290: Control System 300: Equipment 305: Detection device 330: Controller 360: Fluorine Sensor 365: Flow Control Devices 370: Measuring Vessel 375: Measuring cavity 400: Equipment 405: Detection device 470: Buffer container 500: Equipment 505: Detection device 507_1, 507_2…507_i: gas mixture 510: Chamber 510_1, 510_2…510_i: Chamber 516: Sensing Device 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: The first stage 602: Second stage 605: Detection device 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: Elongated electrode 630_2: Elongated 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 Dump 690: Control System 700: memory 705: Input Device 710: Output device 715: Processor 720: Computer Program Products 730: Controller 731: Gas Maintenance Module 732: lithography module 790: Control System 800: Equipment 804: Fluorine Scrubber 805: Detection device 807: Gas mixture 820: Gas Maintenance System 835: Fluorine Scrubber 845: Hydroxide 820: Gas Maintenance System 851A: Triad gas source 851B: Double gas source 852: Valve System 870: Buffer 891: Valve 900: Procedure 905: Steps 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 apparatus configured to measure the concentration of fluorine in a gas mixture within a chamber;

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

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

4 is a block diagram of an implementation of the apparatus of FIG. 1, wherein the detection apparatus includes a buffer container;

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

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

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

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

9 is a flow chart of a procedure performed by a detection apparatus for detecting the concentration of fluorine in a gas mixture of a chamber;

Figure 10 is a flow diagram of the procedure performed by the apparatus once the fluorine concentration has been estimated and after the procedure of Figure 9 has been completed; and

FIG. 11 is a flow chart of a procedure performed by a detection apparatus instead of the procedure of FIG. 9 to estimate the concentration of fluorine in the gas mixture in the chamber.

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: Measuring cavity

177: Casing

400: Equipment

405: Detection device

470: Buffer container

Claims (36)

A method for gas detection, comprising: receiving at least a portion of a mixed gas from a gas discharge chamber, wherein the mixed gas includes fluorine; combining the fluorine in the mixed gas portion with a hydroxide reacting 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 portion of the mixed gas based on the sensed concentration of water. The method of claim 1, wherein the hydroxide comprises an alkaline earth metal hydroxide. The method of claim 1, wherein the hydroxide lacks an alkali metal and carbon. The method of claim 1, wherein the mixed gas is an excimer laser gas comprising at least a mixture of a gain medium and a buffer gas. The method of claim 1, further comprising: adjusting a relative concentration of fluorine in a gas mixture from a set of gas suppliers based on the estimated concentration of fluorine in the mixed gas portion; and by combining the adjusted gas mixture A gas refresh is performed from the gas supplies added to the gas discharge chamber. The method of claim 5, wherein performing the gas refresh comprises filling the gas discharge chamber with a mixture of a gain medium and a buffer gas and fluorine. The method of claim 6, wherein filling the gas discharge chamber with the mixture of the gain medium and the buffer gas comprises: filling the gas discharge chamber with a gain medium, the gain medium comprising a noble gas and a halogen, and Include an inert gas or a buffer gas. The method of claim 7, wherein the noble gas comprises argon, krypton or xenon; the halogen comprises fluorine; and the noble gas comprises helium or neon. The method of claim 6, wherein filling the gas discharge chamber with the mixture of the gain medium and the buffer gas and fluorine comprises: adding the gain medium and the mixture of the buffer gas and fluorine into the gas discharge chamber an existing gas mixture; or at least replace an existing gas mixture in the gas discharge chamber with the mixture of the gain medium, the buffer gas and fluorine. The method of claim 5, wherein performing the gas refresh comprises performing one or more of a gas refill scheme or a gas injection scheme. The method of claim 1, wherein receiving at least the portion of the mixed gas from the gas discharge chamber comprises: receiving the mixed gas portion prior to performing a gas refresh of the gas discharge chamber, wherein the gas refresh comprises converting a gas The mixture is added to the gas from a set of gas supplies a discharge chamber, wherein the gas mixture includes at least some fluorine. The method of claim 11, wherein performing the gas refresh comprises performing one or more of a gas refill scheme or a gas injection scheme. The method of claim 1, wherein receiving at least the portion of the mixed gas from the gas discharge chamber comprises: releasing the mixed gas from the gas discharge chamber; and directing the released mixed gas to a chamber containing the hydroxide a reaction vessel. The method of claim 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 in the measurement vessel This concentration of water in the new gas mixture. 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. The method of claim 1, further comprising discharging the new gas mixture from the measurement vessel after the concentration of fluorine in the mixed gas portion has been estimated. 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 the mixed gas portion with another material. The method of claim 1, wherein reacting the mixed gas portion with the hydroxide to form the new gas mixture comprising water comprises forming an inorganic fluoride compound plus water. The method of claim 18, wherein the hydroxide comprises calcium hydroxide and the inorganic fluoride compound comprises calcium fluoride. 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 the reaction begins. The method of claim 1, wherein the mixed gas portion is an exhaust gas and reacting the mixed gas portion with the hydroxide to form the new gas mixture including water comprises removing fluorine from the exhaust gas. The method of claim 1, wherein estimating the concentration of fluorine in the mixed gas portion based on the sensed concentration of water comprises: based solely on the sensed concentration of water and fluorine in the mixed gas portion and the mixed gas portion The chemical reaction between the hydroxides is estimated. The method of claim 1, wherein the concentration of fluorine in the mixed gas portion is about 500 to 2000 parts per million. The method of claim 1, wherein the reaction of the fluorine and the hydroxide in the portion of the mixed gas forming the new gas mixture comprising water is stable. The method of claim 1, wherein reacting the fluorine in the mixed gas portion with the hydroxide to form the new gas mixture including water comprises: performing a reaction that is linear and provides the fluorine in the mixed gas portion A direct correlation between the concentration of fluorine and the concentration of the water in the fresh gas mixture. The method of claim 1, further comprising sensing a concentration of oxygen within the new gas mixture, wherein estimating the concentration of fluorine within the mixed gas portion is also based on the sensed concentration of oxygen. A method for gas detection, comprising: performing a first gas update by adding a first gas mixture to a gas discharge chamber from a set of gas suppliers; removing after the first gas update at least a portion of a mixed gas from the gas discharge chamber, wherein the mixed gas includes fluorine; reacting the fluorine of the removed portion of the mixed gas with a reactant to form a new gas mixture including oxygen and water; sensing measuring a concentration of water in the new gas mixture; estimating a concentration of fluorine in the removed mixed gas portion based on the sensed concentration of water; based on the concentration of fluorine in the removed mixed gas portion Adjusting a relative concentration of fluorine in a second gas mixture from a second gas mixture of the set of gas suppliers; and by adding the adjusted second gas mixture from the gas suppliers to the gas discharge chamber for a second gas update. The method of claim 27, wherein the reactant comprises a hydroxide. The method of claim 27, wherein the mixed gas in the gas discharge chamber comprises an excimer laser gas comprising at least a mixture of a gain medium and a buffer gas. The method of claim 27, wherein estimating the concentration of fluorine in the removed mixed gas portion based on the sensed concentration of water comprises: not measuring the fluorine in the removed mixed gas portion The fluorine concentration in the removed mixed gas portion was estimated in case of concentration. An apparatus for gas detection comprising a detection apparatus fluidly connected to each gas discharge chamber of an excimer gas discharge system, wherein each detection apparatus comprises: a container defining a housing a reaction cavity of 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 the received mixed gas is a reaction between fluorine and the hydroxide capable of forming 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 Sensing an amount of water in the new gas mixture when the new gas mixture is present; and a control system connected to the detection device, the control system configured to: Receive output from the water sensor and estimate a concentration of fluorine in the mixed gas received from the gas discharge chamber; determine whether adjustments from a gas maintenance should be made based on the estimated concentration of fluorine in the mixed gas a concentration of fluorine in a gas mixture of a gas supply system of the system; and sending a signal to the gas maintenance system instructing the gas maintenance system to adjust from the gas maintenance during a gas update to the gas discharge chamber The relative concentration of fluorine in a gas mixture supplied to the gas discharge chamber by the gas supply system of the system. The apparatus of claim 31, wherein each gas discharge chamber of the excimer gas discharge system houses an energy source and contains a gas mixture including an excimer laser gas including a gain medium and fluorine. 31. The apparatus of claim 31, wherein: the detection apparatus further comprises 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 apparatus of claim 31, wherein the concentration of fluorine in the removed portion of the mixed gas is about 500 to 2000 parts per million. The apparatus of claim 31, wherein the excimer gas discharge system includes a plurality of gas discharge chambers, and the detection device is fluidly connected to each gas in the plurality of gas discharge chambers a discharge chamber, wherein the detection apparatus includes a plurality of vessels, each vessel defining a reaction cavity containing the hydroxide, and each vessel is fluidly connected to one of the gas discharge chambers and the detection The testing equipment includes a plurality of water sensors, each oxygen sensor being associated with a container. The apparatus of claim 31, wherein the excimer gas discharge system includes a plurality of gas discharge chambers, and the detection device is fluidly connected to each gas discharge chamber of the plurality of gas discharge chambers, wherein the detection device The detection apparatus includes a plurality of vessels, each vessel defining a reaction cavity containing the hydroxide, and each vessel is fluidly connected to one of the gas discharge chambers and the detection apparatus includes and all of the A single water sensor fluidly connected to the container.

Images