Device for light source, blower controller for light source, and ultraviolet light source

Abstract

In some general aspects, an apparatus for a light source includes a monitoring module configured to monitor a fault condition of one or more operating conditions of the light source, a decrement module configured to reduce an operating speed of a blower disposed in a gas discharge chamber of the light source when the fault condition for the one or more operating conditions of the light source is clear and a reduced operating speed is equal to or greater than a baseline speed, and an increment module configured to increase an operating speed of the blower when a fault condition for the one or more operating conditions of the light source is flagged, The blower is configured to move a gas mixture including a gain medium through the gas discharge chamber from an energy source configured to provide energy to the gas mixture.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0001] This application claims the priority of U.S. Application No. 63 / 129,122, entitled REDUCING ENERGY CONSUMPTION OF A GAS DISCHARGE CHAMBER BLOWER, filed on December 22, 2020, the entire disclosure of which is incorporated herein by reference.

[0002]

[0002] The disclosed subject matter relates to reducing the energy consumed by a blower during operation of a light source by controlling a blower disposed in a gas discharge chamber of the light source.

Background Art

[0003]

[0003] One type of gas discharge light source used in photolithography is called an excimer light source or laser. Generally, an excimer laser uses a combination of one or more noble gases that may include argon, krypton, or xenon, and a reactive gas that may include fluorine or chlorine. An excimer laser can generate an excimer (pseudo - molecule) under appropriate conditions of electrical simulation (energy supplied) and high pressure (of the gas mixture), and the excimer exists only in an excited state. The excited - state excimer produces amplified light in the ultraviolet region. An excimer light source can use a single gas discharge chamber or multiple gas discharge chambers. When an excimer light source is operating, the excimer light source generates a deep ultraviolet (DUV) light beam. The DUV light can include wavelengths, for example, from about 100 nanometers (nm) to about 400 nm.

[0004]

[0004] The DUV light beam may be directed to a photolithography exposure apparatus or scanner, which is a machine that applies a desired pattern to a target portion of a substrate (such as a silicon wafer). The DUV light beam interacts with a projection optics system that projects the DUV light beam onto the photoresist of the wafer through a mask. In this way, one or more layers of the chip design are patterned onto the photoresist, after which the wafer is etched and cleaned. [Overview of the Initiative]

[0005]

[0005] In some general embodiments, the device for a light source comprises a monitoring module configured to monitor fault conditions for one or more operating states of the light source; a decrement module configured to reduce the operating speed of a blower located in the gas discharge chamber of the light source when the fault conditions for one or more operating states of the light source are clear and the decrement operating speed is equal to or greater than the baseline speed; and an increment module configured to increase the operating speed of the blower when the fault conditions for one or more operating states of the light source are flagged. The blower is configured to move a gas mixture, including a gain medium from an energy source configured to supply energy to the gas mixture, within the gas discharge chamber.

[0006]

[0006] The embodiment may include one or more of the following features. For example, the baseline speed of the blower may be related to the years of service of the gas discharge chamber, and the baseline speed changes as the gas discharge chamber ages over time.

[0007]

[0007] Each of the one or more operating states may be defined by performance metrics relating to the light source or the light beam generated by the light source. One or more performance metrics may include a wavelength histogram associated with the light beam, an energy dose error associated with the light beam, an energy error associated with the light beam, and the operating point of the gas discharge chamber in the light source. A fault condition may be flagged if at least one of the relevant performance metrics is not within its threshold range, and the fault condition is cleared if all of the relevant performance metrics are within their corresponding threshold ranges. At least one of the operating states of the light source may be proactive, such that the blower operating speed is adjusted before the value of the relevant performance metric falls outside the threshold range of the performance metric. At least one of the operating states may be reactive, such that the blower operating speed is adjusted after the value of the relevant performance metric falls outside the threshold range of the performance metric. Each active operating state may be associated with a limited threshold range that is narrower than the actual threshold range of the performance metric, and the blower operating speed may be adjusted before the value of the associated performance metric falls outside the actual threshold range by determining the failure condition of the active operating state based on the limited threshold range.

[0008]

[0008] The failure status of one or more operating states of the light source may be determined using a low-pass filter or a weighted sum filter.

[0009]

[0009] A decrement module may be configured to reduce the operating speed of the blower by a decrement speed step size, and an increment module may be configured to increase the operating speed of the blower by an increment speed step size. The increment speed step size may be larger than the decrement speed step size. The increment speed step size may be 25 revolutions per minute (rpm) or less, and the decrement speed step size may be about half, one-third, one-quarter, or one-fifth of the increment speed step size.

[0010]

[0010] The blower's operating speed may be adjusted by an increment module and a decrement module within a blower speed range determined by the minimum blower speed and the maximum blower speed.

[0011]

[0011] The decrement and increment modules may be configured to avoid blower operating speeds at which the aliased frequencies of the blower's second harmonic interfere with the spectral feature control system associated with the light source. The interfering blower operating speed may depend on the repetition rate at which the light source generates the light beam.

[0012]

[0012] The device may also include a baseline module configured to increase the operating speed of the blower if the blower's operating speed falls below the baseline speed.

[0013]

[0013] The device may be a state machine for a light source, where the monitoring module may be in a monitoring state, the decrement module in a decrement state, and the increment module in an increment state. After reducing the blower's operating speed in the decrement state, the state machine can transition from the decrement state to the increment state if a fault condition relating to one or more operating states of the light source is flagged. The state machine may include a baseline state configured to increase the blower's operating speed when the blower's operating speed falls below the baseline speed, and the state machine can transition from the decrement state to the baseline state when the blower's operating speed falls below the baseline speed. After the baseline state increases the blower's operating speed in the baseline state, the state machine can transition from the baseline state to the increment state if a fault condition relating to one or more operating states of the light source is flagged. The state machine can transition from the monitoring state to the baseline state when the blower's operating speed falls below the baseline speed. After increasing the blower's operating speed in the increment state, the state machine can transition from the increment state to the monitoring state if the blower's increasing operating speed is greater than the target speed. The state machine can transition from the monitoring state to the increment state if a fault condition related to one or more operating states of the light source is flagged. The state machine can transition from the monitoring state to the decrement state if one or more termination criteria are met, the termination criteria being based on one or more of the baseline speed, the number of light beam pulses generated by the light source, and events that result in an improvement in the performance of the light source.

[0014]

[0014] In other common embodiments, a blower controller for a light source comprises a control system in communication with a blower located in the gas discharge chamber of the light source, the blower configured to move a gas mixture, including a gain medium from an energy source configured to supply energy to the gas mixture, within the gas discharge chamber. The control system monitors fault conditions for one or more operating states of the light source and is configured to decrement the blower's operating speed in a decrement state if the fault conditions for one or more operating states of the light source are clear and the decrementing operating speed is equal to or greater than the baseline speed, and to increase the blower's operating speed in an increment state if the fault conditions for one or more operating states of the light source are flagged.

[0015]

[0015] An embodiment may include one or more of the following features. For example, the control system may include a computer-readable memory module and one or more electronic processors coupled to the computer-readable memory module.

[0016]

[0016] A fault status for one or more operating states may be defined using binary, where a value of 0 is assigned to the fault status if the fault status is clear, and a value of 1 is assigned to the fault status if a flag is set.

[0017]

[0017] The control system may be configured to increase the blower's operating speed in an increment state if the blower's decreasing operating speed falls below the baseline speed.

[0018]

[0018] In other common embodiments, a method is performed to control a blower located within the gas discharge chamber of a light source. The method includes monitoring fault conditions for one or more operating states of the light source, decrementing the blower's operating speed if the fault conditions for one or more operating states of the light source are clear and the reduced operating speed is equal to or greater than the baseline speed, and incrementing the blower's operating speed if the fault conditions for one or more operating states of the light source are flagged.

[0019]

[0019] An embodiment may include one or more of the following features. For example, the operating speed of a blower may be decremented by reducing the amount of vibration in the light source caused by the movement of the blower. The operating speed of a blower may be decremented by decreasing the operating speed of the blower by a decrement speed step size, and the operating speed of a blower may be incremented by increasing the operating speed of the blower by an increment speed step size. The method may further include determining the increment speed step size and the decrement speed step size of the blower, each depending on a fault condition relating to one or more operating states of the light source.

[0020]

[0020] The blower's operating speed may be decremented and incremented by adjusting the blower's operating speed within a range defined by the minimum and maximum blower speeds. The method may also include determining the blower's blower speed range depending on the failure conditions of one or more operating states of the light source.

[0021]

[0021] The method may further include incrementing the blower's operating speed if the blower's decreasing operating speed falls below the baseline speed.

[0022]

[0022] Failure conditions relating to one or more operating states may be monitored by monitoring one or more termination criteria, such that the blower operating speed is reduced only if one or more of the termination criteria are met. The termination criteria may be based on a baseline speed and the number of light beam pulses generated by the light source, and the termination criteria are met when the blower operating speed is greater than the baseline speed and the number of light beam pulses is greater than the minimum number of pulses.

[0023]

[0023] In other common embodiments, the ultraviolet light source comprises one or more gas discharge chambers configured to hold a gas mixture containing a gain medium, house an energy source configured to supply energy to the gas mixture, and generate a light beam, at least one of which is configured to hold a blower configured to move the gas mixture from the energy source within the gas discharge chamber, and a device configured to adjust the operating speed of the blower. The device comprises a monitoring module configured to monitor fault conditions relating to one or more operating states of the light source, a decrement module configured to reduce the operating speed of the blower when the fault conditions relating to one or more operating states of the light source are clear and the decremented operating speed is equal to or greater than the baseline speed, and an increment module configured to increase the operating speed of the blower when a fault condition relating to one or more operating states of the light source is flagged.

[0024]

[0024] An embodiment may include one or more of the following features. For example, the gain medium may be configured to emit deep ultraviolet (DUV) light in response to a voltage signal being applied to an energy source. The gas gain medium may include argon fluoride (ArF), krypton fluoride (KrF), or xenon chloride (XeCl). The photogenerator may comprise two gas discharge chambers, each having a main oscillator configured to generate a seed light beam and a power amplifier configured to generate an output light beam from the seed light beam. The photogenerator may comprise a plurality of gas discharge chambers, each of which may be configured to emit a light beam toward a beam combiner.

[0025]

[0025] The device may include a baseline module configured to increase the operating speed of the blower when the blower's decreasing operating speed falls below the baseline speed. [Brief explanation of the drawing]

[0026] [Figure 1]

[0026] An ultraviolet light source that generates a light beam used by a lithography exposure apparatus, the ultraviolet light source including a light generation device having one or more gas discharge chambers each having a blower and a device configured to at least partially control the speed of the blower. [Figure 2]

[0027] Block diagram of an embodiment of the apparatus of FIG. 1 including a monitoring module, a decrement module, an increment module, and optionally a baseline module. [Figure 3]

[0028] Schematic diagram showing how the overall fault situation of a light source is determined based on one or more operating states of the light source for use by the apparatuses of FIGS. 1 and 2. [Figure 4A]

[0029] Exemplary graph showing how the baseline speed varies with the years of use of a discharge chamber for various discharge chambers. [Figure 4B]

[0029] Exemplary graph showing how the baseline speed varies with the years of use of a discharge chamber for various discharge chambers. [Figure 4C]

[0029] Exemplary graph showing how the baseline speed varies with the years of use of a discharge chamber for various discharge chambers. [Figure 5]

[0030] State machine showing an embodiment of the apparatus, the state machine including a monitoring state (executed by the monitoring module), a decrement state (executed by the decrement module), and an increment state (executed by the increment module). [Figure 6A]

[0031] Flowchart of the procedure executed by the decrement module while the state machine is in the decrement state. [Figure 6B]

[0032] Flowchart of the procedure executed by the monitoring module while the state machine is in the monitoring state. [Figure 6C]

[0033] This is a flowchart of the steps performed by the baseline module while the state machine is in the baseline state. [Figure 6D]

[0034] This is a flowchart of the steps performed by the increment module while the state machine is in the increment state. [Figure 7A]

[0035] Figures 1 and 2 are flowcharts of the procedure performed by the device for controlling the speed of the light source blower. [Figure 7B]

[0036] This is an additional step that may be included in the procedure shown in Figure 7A. [Figure 8]

[0037] This is a block diagram of an embodiment of a light source in which the photogenerator has a main oscillator-power amplifier configuration and two gas discharge chambers. [Figure 9A]

[0038] This is a block diagram of an embodiment of a light source equipped with multiple gas discharge chambers and an embodiment of a lithography exposure apparatus. [Figure 9B]

[0039] Figure 9A is a block diagram of an embodiment of the projection optics system of a lithography exposure apparatus. [Modes for carrying out the invention]

[0027]

[0040] Referring to Figure 1, the ultraviolet light source 100 comprises a photogenerator 105 having one or more gas discharge chambers 104 and a device 110. In the example in Figure 1, the photogenerator 105 has one discharge chamber 104, but it may also have multiple discharge chambers 104 (as shown in Figures 8 and 9A). The gas discharge chamber 104 is configured to house an energy source 106 configured to generate a light beam 102 by holding a gas mixture 107 containing a gain medium within the internal cavity 104i of the gas discharge chamber 104 and supplying energy to the gas mixture 107. The gain medium of the gas mixture 107 is configured to emit deep ultraviolet (DUV) light in response to a voltage signal being applied to the energy source 106. The energy source 106 may be configured to supply energy to the gas mixture 107 in short (e.g., nanosecond) current pulses using a high-voltage discharge with intermittent periods of no energy. The gas mixture 107 generates pulses of the light beam 102 from the population inversion that occurs in the gain medium of the gas mixture 107 by stimulated emission when energy from the energy source 106 is supplied to the gas mixture 107. Therefore, the light beam 102 is a pulsed light beam containing pulses of light centered on wavelengths within the DUV range, including, for example, 248 nanometers (nm) or 193 nm. In the case of a DUV light source, the gas gain medium of the gas mixture 107 may include, for example, argon fluoride (ArF), krypton fluoride (KrF), or xenon chloride (XeCl). The light beam 102 is directed along a path to the lithography exposure apparatus 101. The light beam 102 is used to pattern microelectronic features onto a substrate or wafer accepted by the lithography exposure apparatus 101. The size of the microelectronic features patterned on the wafer depends on the wavelength of the pulsed light beam 102, with lower wavelengths resulting in smaller minimum feature sizes or critical dimensions. For example, if the wavelength of the pulsed light beam 102 is 248 nm or 193 nm, the minimum size of the microelectronic feature may be, for example, 50 nm or less.

[0028]

[0041] Specifically, the energy source 106 may have a cathode and an anode, and the potential difference between the cathode and the anode forms an electric field in the gas mixture 107. The electric field causes population inversion and provides sufficient energy to the gain medium in the gas mixture 107 to enable the generation of light pulses by stimulated emission. The repeated generation of such a potential difference ultimately forms a train of light pulses that constitutes the light beam 102. A "discharge event" is the application of a voltage that forms a potential difference sufficient to cause a discharge in the gain medium of the gas mixture 107 and the emission of light pulses.

[0029]

[0042] When an optical pulse is generated from the gas mixture 107 near the energy source 106, there is a period of recovery for the molecules in the gas mixture 107. This recovery period is longer than the time between pulses of the energy source 106. Furthermore, if another pulse of energy is supplied to the recovering gas mixture 107 that remains closest to the energy source 106, the output quality of the optical pulses of the resulting optical beam 102 will be reduced, potentially leading to a malfunction of the photogenerator 105. To solve this problem, the gas discharge chamber 104 holds a blower 108 mounted on the walls 103A, 103B of the gas discharge chamber 104. In various embodiments, the blower 108 may have a rotating structure such as a fan. For example, see U.S. Patent No. 6,765,946, issued July 20, 2004, in the name of the inventors, Partlo, et al., which is incorporated herein by reference in its entirety. The blower 108 is configured to periodically move portions of the recovering gas mixture 107 away from the energy source 106 within the gas discharge chamber 104 so that the fresh gas mixture 107 can interact with the energy source 106 before the next pulse of the energy source 106 is generated. If the speed of the blower 108 is too low, arcing, dropouts, and inefficiencies may occur in the gas discharge chamber 104, and the gas discharge chamber 104 may become non-functional if the blower 108 is unable to adequately remove portions of the recovering gas mixture 107. Another consideration is that the rotation or motion of the blower 108 may cause vibrations within the gas discharge chamber 104 that may affect one or more spectral characteristics of the light beam 102 and the dose performance of the light beam 102 in the lithography exposure apparatus 101.

[0030]

[0043] While the light source 100 is operating, the operating speed of the blower 108 (which is the speed or rate at which the blower 108 rotates around its axis of rotation) may be maintained at a constant, preset speed. Specifically, the operating speed of the blower 108 may be maintained at the maximum blower speed so that the blower's operating speed 108 does not change over time when the light source 100 is operating. Under such conditions, the blower 108 may consume a nearly constant amount of energy over time, in other words, it may be costly and at least not cost-effective because it requires a constant amount of power when the light source 100 is operating. Therefore, as discussed herein, the operating speed of the blower 108 is changed or adjusted over time (when the light source 100 is operating) by the device 110 based on the fault conditions of one or more operating states of the light source 100 and the baseline speed of the blower 108 (which is the minimum allowable speed of the blower 108). Thus, the device 110 functions as a blower controller that controls the operating speed of the blower 108 by adjusting its operating speed between a minimum blower speed and a maximum blower speed, which together define a safe blower speed range for the blower 108 while the light source 100 is operating. In other words, when the light source 100 is operating, the device 110 adjusts the operating speed of the blower 108 within a safe blower speed range that does not cause any faults and / or problems within the light source 100, and also adjusts the operating speed of the blower 108 so that more energy is saved by the blower 108, and as a result, less energy is consumed by the light source 100. Details of the device 110 are shown below.

[0031]

[0044] Referring to Figure 2, the device 110 (i.e., the blower controller) comprises a monitoring module 112, a decrement module 114, and an increment module 116.

[0032]

[0045] Generally, the monitoring module 112 is configured to monitor fault conditions relating to one or more operating states of the light source 100. For example, each of the one or more operating states may be defined by a performance metric relating to the light source 100 or the light beam 102 generated by the light source 100. A fault condition may be considered flagged if at least one of the relevant performance metrics is not within its threshold range, and the fault condition is considered clear if all of the relevant performance metrics are within their respective threshold ranges. Thus, when the light source 100 is operating, the monitoring module 112 can monitor one or more operating states of the light source 100 by monitoring one or more relevant performance metrics.

[0033]

[0046] Generally, the decrement module 114 is configured to reduce the operating speed of the blower 108 when one or more fault conditions related to the operating state of the light source 100 are clear and the reduced operating speed is equal to or greater than the baseline speed of the blower 108 (which is the minimum allowable speed of the blower 108). For example, the decrement module 114 may be configured to reduce the operating speed of the blower 108 by the decrement speed step size.

[0034]

[0047] Generally, the increment module 116 is configured to increase the operating speed of the blower 108 when one or more operational fault conditions of the light source 100 are flagged. The increment module 116 may be configured to increase the operating speed of the blower 108 by an increment speed step size. In one example, the increment step size may be, for example, 25 revolutions per minute (rpm) or less. In this example, the increment speed step size is greater than the decrement speed step size, and the decrement speed step size may be about half, one-third, one-quarter, or one-fifth of the increment speed step size.

[0035]

[0048] The device 110 may also include a baseline module 118 configured to increase the operating speed of the blower 108 if the operating speed of the blower 108 falls below the baseline speed.

[0036]

[0049] When the light source 100 is operating, the operating speed of the blower 108 is adjusted by the increment and decrement modules 114, 116 and the baseline module 118 within a blower speed range determined by the minimum and maximum blower speeds. The blower speed range is a safe range in which the light source 100 operates properly without problems and / or malfunctions. In this way, the device 110 controls the operating speed of the blower 108 by adjusting its operating speed within a safe blower speed range so that the blower 108 consumes the minimum amount of energy and the energy consumed by the light source 100 is reduced.

[0037]

[0050] Modules 112, 114, 116, and 118 of device 110 may be implemented in a control system that controls the blower 108 by being in communication with the blower 108. Therefore, the control system of the blower controller 108 is configured to monitor fault conditions for one or more operating states of the light source 100, and to decrement the operating speed of the blower 108 if the fault conditions for one or more operating states of the light source 100 are clear and the decrementing operating speed is equal to or greater than the baseline speed, and to increment the operating speed of the blower 108 if a flag is set for one or more operating states of the light source 100. The control system of the blower controller 110 may also be configured to increment the operating speed of the blower 108 if the decrementing operating speed of the blower 108 falls below the baseline speed.

[0038]

[0051] The device 110 may comprise, for example, a computer-readable memory module and one or more electronic processors coupled to the computer-readable memory module. Each of modules 112, 114, 116, and 118 may be in communication with the memory module and may be controlled by one or more electronic processors. For example, each module 112, 114, 116, and 118 may have or be able to access one or more programmable processors, each capable of executing a program of instructions that perform a desired function by acting on input data and producing appropriate outputs. Each module 112, 114, 116, and 118 may be implemented in digital electronic circuits, computer hardware, firmware, or software. In further embodiments, each module 112, 114, 116, 118 accesses memory in a memory module that is also configured to store information that modules 112, 114, 116, 118 can use in various ways during the operation of the device 110, such as information output from one or more modules 112, 114, 116, 118, information from the gas discharge chamber 104, or information about other aspects of the photogenerator 105. The memory in the memory module may be read-only memory and / or random-access memory and may provide a storage device suitable for tangibly embodying computer program instructions and data. The device 110 may also include one or more input devices (such as a keyboard, a touch-enabled device, or an audio input device) and one or more output devices (such as an audio output or a video output).

[0039]

[0052] In an example where device 110 functions as a blower controller, fault conditions for one or more operating states may be defined using binary (by the control system). Specifically, fault conditions may be assigned a value of zero (0) if the fault condition is clear, or a value of 1 if the fault condition is flagged. Details of fault conditions for one or more operating states of light source 100 are shown below.

[0040]

[0053] Referring to Figure 3, the overall fault condition 327 of the light source 100 is determined by the device 110 in each iteration based on one or more operating states of the light source 100. Each of the one or more operating states is defined by performance metrics 320_1 to 320_N relating to the light source 100 or the light beam 102 generated by the light source 100. The fault condition 327 that the device 110 uses to control the blower 108 must be based on system parameters, metrics, and signals that are significantly affected by changes in the speed of the blower 108.

[0041]

[0054] In the example shown in Figure 3, one or more performance metrics 320_1 to 320_N include spectral feature accuracy associated with the light beam 102, energy dose error associated with the light beam 102, energy error associated with the light beam 102, actuator operating point of the photogenerator 105 in the light source 100, and gas discharge chamber dropout rate.

[0042]

[0055] Spectral feature accuracy represents the stability and precision of the spectral features (such as wavelength) of the light beam 102 generated by the light source 100. Specifically, the spectral feature accuracy with respect to wavelength is based on the mean and standard deviation of the wavelength error of the light beam 102, calculated over a moving window of M pulses (where M is an integer greater than or equal to 1) of the light beam 102. The value of spectral feature accuracy may be directly measured / calculated or estimated from other measurement data.

[0043]

[0056] The energy dose error represents the difference between the desired or target dose on the wafer and the actual dose on the wafer received by the lithography exposure apparatus 107. The dose on the wafer is the amount of light energy per unit area delivered by the light beam 102 over the exposure time, or a specific number of pulses on the wafer. While the energy dose error can be directly measured / calculated, it can also be estimated from other measurement data.

[0044]

[0057] The energy error represents the standard deviation of the measured energy of the light beam 102. Specifically, the energy error can be considered the difference between the pulse energy of the light beam 102 and the amount of target energy. While the energy error can be measured directly, it can also be estimated from other data.

[0045]

[0058] The actuator operating point of the photogenerator 105 characterizes the location where the actuator is operating within the photogenerator 105, within a range of possible settings, values, or conditions. In some embodiments, as discussed below with reference to Figure 8, the actuator may be a timing module coupled to a first stage of the photogenerator 805, which includes a first discharge chamber 804A (the first stage constitutes the main oscillator), and a second stage, which includes a second discharge chamber 804B (the second stage constitutes the power amplifier). Such a timing module controls the relative timing between a first trigger signal transmitted to a first energy source 806A in the first discharge chamber 804A and a second trigger signal transmitted to a second energy source 806B in the second discharge chamber 804B. This relative timing may be referred to as differential timing. In these embodiments, the metric of the actuator operating point of the photogenerator 805 can quantify the actual relative timing displacement from the peak efficiency differential timing (Tpeak). Here, Tpeak is the relative timing value at which the photogenerator 805 generates a light beam 802 with maximum energy at a specific input energy applied to the photogenerator 805 (via energy sources 806A and 806B). The metric of this actuator operating point may be calculated or estimated based on the voltage or energy supplied to energy sources 806A and 806B, the output energy of the light beam 802, and the differential timing.

[0046]

[0059] The gas discharge chamber dropout rate quantifies the failure mechanism in which the gas mixture does not move quickly enough within the gas discharge chamber 104 because the blower 108 is unable to adequately remove the portion of the gas mixture 107 that is recovering, resulting in arc discharge and energy loss within the gas discharge chamber 104.

[0047]

[0060] In some embodiments, as discussed above, one or more of the performance metrics 320_1 to 320_N for the light source 100 may be unavailable at a particular moment in operation or within a particular system, and the device 110 can estimate the value of the unavailable performance metric to determine the failure condition 327 based on other available data. To calculate the overall failure condition 327, the device 110 receives the performance metrics 320_1, 320_2, ..., 320_N.

[0048]

[0061] Each of the one or more performance metrics 320_1 to 320_N is associated with a corresponding value 321_1 to 321_N that passes through the corresponding filter 322_1 to 322_N to eliminate any noise effects or transient performance problems that may occur during operation. For example, each of the filters 322_1 to 322_N may be a low-pass filter or a weighted sum filter, so that a fault condition 327 relating to one or more operating states 320_1 to 320_N of the light source 100 is determined using the filters 322_1 to 322_N (including low-pass filters or weighted sum filters). Also, each of the filters 322_1 to 322_N may have a configurable transfer function for filtering the values ​​321_1 to 321_N of the performance metrics 320_1 to 320_N.

[0049]

[0062] The filtered values ​​323_1 to 323_N of performance metrics 320_1 to 320_N are output from the corresponding filters 322_1 to 322_N. In order to determine the corresponding failure conditions 325_1 to 325_N associated with each of the performance metrics 320_1 to 320_N (i.e., operating states), each of the filtered values ​​323_1 to 323_N is compared with the corresponding threshold range 324_1 to 324_N associated with that performance metric 320_1 to 320_N. If it is determined that the corresponding performance metric 320_1 to 320_N is not within the threshold range 324_1 to 324_N of that performance metric 320_1 to 320_N, the failure condition 325_1 to 325_N of that performance metric 320_1 to 320_N is flagged. If the corresponding performance metric 320_1~320_N is determined to be within the threshold range 324_1~324_N of that performance metric 320_1~320_N, then the failure status 325_1~325_N of that performance metric 320_1~320_N is clear. As described above, failure status 325_1~325_N may be assigned a value of zero (0) if failure status 325_1~325_N is clear, or a value of 1 if a flag is set for failure status 325_1~325_N.

[0050]

[0063] Each fault condition 325_1 to 325_N is input to a fault condition module 326 (which may be a controller) that determines the overall fault condition 327 of the light source 100 based on the fault conditions 325_1 to 325_N of the performance measurement criteria 320_1 to 320_N associated with the light source 100. For example, in some embodiments, if any one of the fault conditions 325_1 to 325_N is flagged (i.e., given a value of 1), the overall fault condition 327 of the light source 100 is flagged (i.e., given a value of 1). And if all of the fault conditions 325_1 to 325_N are clear (i.e. have a value of 0), the overall fault condition 327 of the light source 100 is clear (i.e. has a value of 0). In this way, the overall fault condition 327 of the light source 100 can be determined, and the device 110 can control the blower 108 based on the fault condition 327 of the light source 100, thereby reducing the energy consumption of the blower 108 during operation. In other embodiments, the fault status module 326 may be configured to flag the overall fault status 325 only if multiple fault statuses 325_1 to 325_N are flagged.

[0051]

[0064] Next, details of the baseline speed of Blower 108 are shown.

[0052]

[0065] Referring to Figures 4A to 4C, the baseline speed of the blower 108 may be related to the age of the gas discharge chamber 104. In the examples in Figures 4A to 4C, the baseline speed changes as the gas discharge chamber 104 ages over time. In other words, the baseline speed changes as the number of pulses in the light beam 102 generated by the gas discharge chamber 104 increases over time (and as the gas discharge chamber 104 ages). In these examples, the device 110 adjusts the baseline operating speed of the blower 108 between a minimum baseline speed bmin and a maximum baseline speed bmax. One or another module of the device 110, such as modules 114, 116, or 118, may perform this adjustment. Generally, the baseline speed of the blower 108 needs to be increased as the gas discharge chamber 104 ages and performance failures, performance problems, and / or performance errors occur more frequently within the aging light source 100 (and within the gas discharge chamber 104). As the discharge chamber 104 ages, increasing the baseline speed of the gas discharge chamber 104 reduces or mitigates performance failures, performance problems, and / or performance errors that may occur within the aging light source 100.

[0053]

[0066] In the example shown in Figure 4A, the device 110 adjusts the baseline speed from the maximum baseline speed bmax to the minimum baseline speed bmin at time t1a. At this time, the device 110 begins to gradually increase the baseline speed. The baseline speed of the blower 108 is incremented at a constant rate of 429a (i.e., slope) as the gas discharge chamber 104 ages over time (or as pulses of the light beam 102 are generated by the gas discharge chamber 104). The baseline speed of the blower 108 is increased or incremented from the minimum baseline speed bmin to the maximum baseline speed bmax at time t2a, which is the end of the life of the gas discharge chamber 104.

[0054]

[0067] In the example shown in Figure 4B, the device 110 adjusts the baseline speed from the maximum baseline speed bmax to the minimum baseline speed bmin at time t1b. While the gas discharge chamber 104 is still relatively new (dL between time t1b and time t2b), the baseline speed of the blower 108 remains constant at the minimum baseline speed bmin. Because the gas discharge chamber 104 is still relatively new (dL between time t1b and time t2b), in this example, it is not necessary to increase the baseline speed to mitigate or alleviate performance problems within the light source 100.

[0055]

[0068] At time t2b, the device 110 begins to increase or increment its baseline speed. The baseline speed of the blower 108 is increased at a constant rate of 429b (i.e., slope) as the gas discharge chamber 104 ages and deteriorates over time (and as pulses of the light beam 102 are generated by the gas discharge chamber 104). The baseline speed of the blower 108 is increased or incremented from the minimum baseline speed bmin to the maximum baseline speed bmax, so that the baseline speed reaches the maximum baseline speed bmax at time t3b, which is the end of the life of the gas discharge chamber 104.

[0056]

[0069] The example in Figure 4C is similar to the example in Figure 4B, except that the baseline speed of blower 108 remains constant for a shorter time dS, and the baseline speed is incremented at a slower rate of 429c than at a rate of 429b. The baseline speed is decremented to a minimum baseline speed bmin at time t1c, and this minimum baseline speed bmin is maintained for time dS. Then, at time t2c, the baseline speed increases at a constant rate of 429c as the gas discharge chamber 104 ages and deteriorates over time, until the baseline speed of blower 108 reaches a maximum baseline speed bmax at time t3c, which is the end of the life of the gas discharge chamber 104.

[0057]

[0070] Referring to Figure 5, the device 110 (Figure 2) is represented as a state machine 510 for the light source 100. In this representation of the state machine 510, the monitoring module 112 is represented by the monitoring state 512, the decrement module 114 is represented by the decrement state 514, and the increment module 116 is represented by the increment state 516. The state machine 510 may also include a baseline state 518 representing the baseline module 118 (Figure 2). In this embodiment, the state machine 510 also includes a passive state 511 in which there are no commands or instructions from the state machine 510 for changing or adjusting the operating speed of the blower 108.

[0058]

[0071] The state machine 510 transitions from the passive state 511 to the decrement state 514 (T(PD)) when the number of pulses of the light beam 102 generated from the gas discharge chamber 104 exceeds a threshold, or after the state machine 510 has been in the passive state 511 for a threshold period. Generally, the decrement state 514 is configured to reduce the operating speed of the blower 108 when one or more fault conditions 327 relating to the operating state of the light source 100 are clear and the reduced operating speed is equal to or greater than the baseline speed.

[0059]

[0072] Specifically, as also referring to Figure 6A, in the decrement state 514, the decrement module 114 determines whether the fault status 327 of the light source 100 is clear (e.g., 0) (532). If the fault status 327 is not clear (i.e., a flag is set or it has a value of 1) (532), the decrement module 114 exits the decrement state 514, and the state machine 510 transitions from the decrement state 514 to the increment state 516 (T(DI)) so that the operating speed of the blower 108 is incremented to a safe operating speed in which no problems and / or faults occur within the light source 100.

[0060]

[0073] If the fault status is clear (i.e., has a value of 0) (532), the decrement module 114 determines whether the operating speed of the blower 108 is greater than the baseline speed (533). If the operating speed of the blower 108 is not greater than the baseline speed (i.e., it is less than or equal to the baseline speed of the blower 108), the decrement module 114 exits the decrement state 514, and the state machine 510 transitions from the decrement state 514 to the baseline state 518 (T(DB)) so that the operating speed of the blower 108 is incremented to a safe operating speed that is above the baseline speed at which no problems and / or faults occur within the light source 100.

[0061]

[0074] If the operating speed of blower 108 is greater than the baseline speed (533), the decrement module 114 determines whether the proposed new blower speed is greater than the baseline speed (534). The proposed new blower speed is the operating speed of blower 108 minus the decrement speed step size. If the proposed new speed of blower 108 is not greater than the baseline speed (i.e., the proposed new blower speed is the baseline speed or less than the baseline speed) (534), the decrement module 114 exits the decrement state 514, and the state machine 510 transitions from the decrement state 514 to the monitoring state 512 (T(DM)) so that it can monitor one or more operating states of the light source 100 and the operating speed of blower 108.

[0062]

[0075] On the other hand, if the proposed new blower speed is greater than the baseline speed (534), the decrement module 114 determines whether the number of pulses of the light beam 102 generated by the gas discharge chamber 104 since the last time the blower speed was changed is greater than the threshold pulse number (541). The threshold pulse number may be preset to a positive integer to reduce the frequency of the blower speed change. For example, the frequency of the blower speed change may be set to ensure that the photogenerator 105 and similar performance metrics have sufficient time to adjust for the effects of the blower speed change. It is also possible to operate in the decrement state 514 without performing this step 541.

[0063]

[0076] If the number of pulses in the light beam 102 generated by the gas discharge chamber 104 is not greater than the threshold number of pulses (i.e., less than or equal to the threshold number of pulses) (541), the decrement module 114 returns to step 532 and repeats steps 532, 533, and 534. If the number of pulses in the light beam 102 generated by the gas discharge chamber 104 is greater than the threshold number of pulses (541), the decrement module 114 instructs the blower 108 to reduce or decrement its operating speed (542). For example, the decrement state 514 can decrement the operating speed of the blower 108 by the decrement speed step size.

[0064]

[0077] After reducing the operating speed of the blower 108 in the decrement state 514 (542), the decrement module 114 returns to querying whether one or more fault conditions 327 relating to the operating states of the light source 100 are clear (for example, have a value of 0) (532).

[0065]

[0078] In short, the decrement module 114 reduces the speed of the blower 108 when there is no fault (532), when the speed of the blower 108 is greater than the baseline speed (533), when the proposed new blower speed is greater than the baseline speed (534), and when a certain number of pulses of the light beam 102 have been generated since the last change in blower speed (541) (524). In this way, the energy consumed by the blower 108 is significantly reduced, especially in the early stages of the lifespan of the light source 100 and the gas discharge chamber 104.

[0066]

[0079] Referring again to Figure 5, as discussed above with reference to Figure 6A, if the proposed new speed of the blower 108 is not greater than the baseline speed (i.e., the proposed new blower speed is the baseline speed or less than the baseline speed) (534), the decrement module 114 exits the decrement state 514, and the state machine 510 transitions from the decrement state 514 to the monitoring state 512 (T(DM)) so that it can monitor one or more operating states of the light source 100 and the operating speed of the blower 108.

[0067]

[0080] Generally, in monitoring state 512, the monitoring module 112 monitors termination criteria and is configured to remain in monitoring state 512 as long as there are no faults, the blower speed is greater than the baseline speed, and no termination criterion events occur. Referring to Figure 6B, in monitoring state 512, the monitoring module 112 determines whether a fault condition 327 relating to one or more operating states of the light source 100 is clear (e.g., has a value of 0) (537). If the fault condition 327 is not clear (i.e., flagged) (537), the state machine 510 transitions from monitoring state 512 to increment state 516 (T(MI)) so that the operating speed of the blower 108 increases to a safe operating speed in which no problems and / or faults occur within the light source 100.

[0068]

[0081] If the fault status is clear (i.e., has a value of 0) (537), the monitoring module 112 determines whether the operating speed of the blower 108 is greater than the baseline speed (538). If the operating speed of the blower 108 is less than the baseline speed (i.e., below it) (538), the state machine 510 transitions from monitoring state 512 to baseline state 518 (T(MB)) so that the operating speed of the blower 108 increases to a safe operating speed in which no problems and / or faults occur within the light source 100. If the operating speed of the blower 108 is greater than the baseline speed (538), the monitoring module 112 determines whether one or more termination criteria have been met (536). For example, the termination criteria may be based on one or more of the baseline speed, the number of pulses of the light beam 102 produced by the light source 100, and events that result in an improvement in the performance of the light source 100. If the termination criteria are met, the state machine 510 transitions from the monitoring state 512 to the decrement state 514 (T(MD)) (because it is determined that the light source 100 is in a state where it is safe to reduce the operating speed of the blower 108). If the termination criteria are not met, the monitoring module 112 returns to determining whether the fault condition 327 for one or more operating states of the light source 100 is clear (e.g., has a value of 0) (537). One possible termination criterion that may be evaluated in step 536 is whether the speed of the blower 108 is greater than the baseline speed plus a lower threshold (e.g., 200 rpm). In this case, it would seem more appropriate to reduce the blower speed (by decrement state 514). Another possible termination criterion that may be evaluated in step 536 is whether the number of pulses of the light beam 102 currently being generated is greater than a predetermined threshold, such as 100 million pulses. Alternatively, instead of evaluating a set of termination criteria in step 536 based on the number of pulses of the generated light beam 102, the monitoring module 112 can evaluate whether a specific performance improvement event has occurred. For example, a performance improvement event could be a gas replenishment or gas injection in which the gas mixture 107 is replaced at least partially or completely.Such events may result in improved performance for light source 100.

[0069]

[0082] Referring again to Figure 5, as discussed above with reference to Figure 6A, when the operating speed of the blower 108 is below the baseline speed (533), the decrement module 114 exits the decrement state 514, and the state machine 510 transitions from the decrement state 514 to the baseline state 518 (T(DB)) so that the operating speed of the blower 108 is incremented to a safe operating speed above the baseline speed where no problems and / or faults occur within the light source 100. The baseline state 518 is discussed with reference to Figure 6C. Generally, the baseline state 518 is configured to increase the operating speed of the blower 108 when its operating speed is below the baseline speed. The baseline module 118 determines whether the fault condition 327 of the light source 100 is clear (e.g., equal to 0) (539). If the fault condition 327 is not clear (and therefore either flagged or has a value of 1) (539), the state machine 510 transitions from baseline state 518 to increment state 516 (T(BI)) so that the operating speed of the blower 108 is incremented to a safe operating speed in which no problems and / or faults occur within the light source 100.

[0070]

[0083] If the fault status is clear (i.e., has a value of 0) (539), the baseline module 118 determines whether the operating speed of the blower 108 is less than the baseline speed (540). If the operating speed of the blower 108 is greater than or equal to the baseline speed (540), the state machine 510 transitions from the baseline state 518 to the monitoring state 512 (T(BM)) (because there is no need to increase the operating speed). On the other hand, if the operating speed of the blower 108 is less than the baseline speed (540), the baseline module 118 determines whether the number of pulses of the light beam 102 generated by the gas discharge chamber 104 since the last time the blower speed changed is greater than the threshold pulse count (548). As discussed above, the threshold pulse count may be preset to a positive integer to reduce the frequency of changes in the blower speed. If the number of pulses in the light beam 102 generated by the gas discharge chamber 104 is less than or equal to the threshold number of pulses (548), the baseline module 118 continues to query whether the number of pulses in the light beam 102 generated by the gas discharge chamber 104 since the last change in blower speed is greater than the threshold number of pulses.

[0071]

[0084] If the number of pulses in the light beam 102 generated by the gas discharge chamber 104 is greater than the threshold number of pulses (548), the baseline module 118 increases or increments the operating speed of the blower 108 (549). For example, the baseline module 118 can increment the operating speed of the blower 108 by an increment speed step size. As an example, the increment speed step size may be approximately 5 revolutions per minute (rpm). After increasing the operating speed of the blower 108, the baseline module 118 returns to step 439 to determine whether the fault condition 327 of the light source 100 is clear (e.g., equal to 0).

[0072]

[0085] Referring again to Figure 5, and as discussed above with reference to Figures 6A to 6C, the state machine 510 can transition from any one of the following states: decrement state 514, monitoring state 512, and baseline state 518, to increment state 516. For example, when in decrement state 514, if the fault condition 327 is not clear (i.e., flagged or has a value of 1) (532), the decrement module 114 exits decrement state 514, and the state machine 510 transitions from decrement state 514 to increment state 516 (T(DI)). Generally, in increment state 516, the operating speed of the blower 108 is incremented to a safe operating speed in which no problems and / or faults occur within the light source 100. Next, we consider the increment state 516 with reference to the embodiment shown in Figure 6D.

[0073]

[0086] Specifically, in increment state 516, the increment module 116 determines whether the fault status 327 of the light source 100 is clear (e.g., 0) (544). If the fault status 327 is not clear (e.g., the fault status is 1) (544), the increment module 116 sets a new target speed for the blower 108 (545). The new target speed for the blower 108 may be equal to the operating speed of the blower 108 plus a large increment speed step size (e.g., 100 rpm). The idea is to significantly increase the speed of the blower 108 when a fault occurs. After the new target speed for the blower 108 is set (545) or after the increment module 116 determines that the fault status is clear (e.g., the fault status is 0) (544), the increment module 116 determines whether the operating speed of the blower 108 is less than the new target speed (535). If the operating speed of the blower 108 is not less than the new target speed (535), that is, if the operating speed of the blower 108 is greater than or equal to the new target speed (535), the state machine 510 transitions from the increment state 516 to the monitoring state 512 (T(IM)).

[0074]

[0087] If the operating speed of the blower 108 is below the target speed (535), the increment module 116 determines whether the number of pulses in the light beam 102 generated by the gas discharge chamber 104 is greater than the threshold number of pulses (546). If the number of pulses in the light beam 102 generated by the gas discharge chamber 104 is less than or equal to the threshold number of pulses, the increment module 116 continues to query whether the number of pulses in the light beam 102 generated by the gas discharge chamber 104 is greater than the threshold number of pulses (546). If the number of pulses in the light beam 102 generated by the gas discharge chamber 104 is greater than the threshold number of pulses, the increment module 116 increases or increments the operating speed of the blower 108 by a specified amount (547). For example, the increment module 116 can increment the operating speed of the blower 108 by an increment speed step size, for example, 25 rpm. After increasing the operating speed of the blower 108 (547), the increment module 116 returns to step 535 to determine whether the upward operating speed of the blower 108 is less than the target speed (535).

[0075]

[0088] Referring more generally to Figure 7A, the apparatus 110 performs procedure 760 for controlling the blower 108. Procedure 760 may be performed on the apparatus 110 (Figure 2) and the light source 100 (Figure 1), which includes the blower 108 in the gas discharge chamber 104. Procedure 760 may also be performed on the state machine 510 (Figure 5). Procedure 760 will be described below in reference to the light source 100, which includes the blower 108.

[0076]

[0089] Procedure 760 includes monitoring the operational status of one or more light sources (761). As discussed above with reference to Figure 6B, for example, the monitoring module 112 monitors the operational status 327 (Figure 3) of one or more light sources 100 (537).

[0077]

[0090] Next, the device 110 decrements the operating speed of the blower 108 if one or more fault conditions related to the operating state of the light source 100 are clear and the decrementing operating speed is equal to or greater than the baseline speed (763). For example, referring to Figure 6A, if one or more fault conditions 327 related to the operating state of the light source 100 are clear (532) and the decrementing operating speed of the blower 108 is greater than the baseline speed (534), the decrement module 114 decrements the operating speed of the blower 108 (542). Decrementing the operating speed of the blower 108 may include reducing the operating speed of the blower 108 by the decrementing speed step size. Decrementing the operating speed of the blower 108 may also include reducing the amount of vibration in the light source 100 caused by the movement of the blower 108.

[0078]

[0091] On the other hand, referring again to Figure 7, the device 110 increments the operating speed of the blower 108 when a fault condition relating to one or more operating states of the light source is flagged (765). Referring to Figure 6D, for example, when a fault condition 327 of the light source 100 is flagged, the increment module 116 increments the operating speed of the blower 108 (547). Incrementing the operating speed of the blower 108 may involve increasing the operating speed of the blower 108 by an increment speed step size. In this way, the increment module 116 prevents the blower 108 from operating at an operating speed that could cause problems and / or faults within the light source 100.

[0079]

[0092] See also Figure 7B, step 760 may further include incrementing the blower's operating speed if the blower's decrementing operating speed falls below the baseline speed (767). Referring to Figure 6C, for example, if the baseline module 118 determines that the blower 108's decrementing operating speed (decremented by the decrement module 114) falls below the baseline speed (540), the baseline module 118 increases or increments the blower 108's operating speed (549). Thus, similar to the increment module 116, the baseline module 118 prevents the blower 108 from operating at an operating speed that could cause problems and / or malfunctions within the light source 100.

[0080]

[0093] For example, decrementing and incrementing the operating speed of blower 108 may involve adjusting the operating speed of blower 108 within a blower speed range defined by a minimum blower speed and a maximum blower speed. In other words, the operating speed of blower 108 is adjusted between the minimum blower speed and the maximum blower speed by increment and decrement modules 114, 116 (and baseline module 118). As described above, the blower speed range is a safe range in which the light source 100 operates properly without problems and / or malfunctions. Thus, the device 110 can control the operating speed of blower 108 by adjusting its operating speed within a safe blower speed range so that the blower 108 consumes the minimum amount of energy and the energy consumed by the light source 100 is reduced.

[0081]

[0094] In some embodiments, step 760 further includes determining the increment speed step size and decrement speed step size of the blower 108, each depending on a fault condition 327 relating to one or more operating states of the light source 100. Specifically, one or more studies of the light source 100 may be performed, for example, by determining the maximum increment speed step size and decrement speed step size that both maintain the stability of the light source 100 and do not adversely affect the performance of the light source 100 (resulting in the fault condition 327 of the light source 100 remaining clear). Step 760 may also further include determining the blower speed range of the blower 108, depending on the fault condition 327 relating to one or more operating states of the light source 100. Similarly, one or more studies of the light source 100 may be performed, for example, by the user determining the minimum and maximum blower speeds (and thus the blower speed range) such that the performance of the light source 100 is not adversely affected when the blower 108 operates within the blower speed range (and consequently, the fault condition 327 of the light source 100 remains clear).

[0082]

[0095] Referring again to Figure 3, in some embodiments, at least one of the operating states of the light source 100 (associated with each performance metric 320_1~320_N) is active, and at least one of the operating states is reactive. Specifically, in the active operating state, the operating speed of the blower 108 is adjusted (for example, by an increment module 116 or a decrement module 114) before the values ​​323_1~323_N of the associated performance metrics 320_1~320_N fall outside the threshold range 324_1~324_N of the performance metrics 320_1~320_N. In reactive operation, the operating speed of the blower 108 is adjusted (for example, by the increment module 116 or the decrement module 114) after the value 323_1~323_N of the relevant performance metric 320_1~320_N falls outside the threshold range 324_1~324_N of the performance metric 320_1~320_N. Furthermore, in some embodiments, each active operating state is associated with a limited threshold range narrower than the actual threshold range 324_1~324_N of the performance metrics 320_1~320_N, and the operating speed of the blower 108 is adjusted (for example by an increment module 116 or a decrement module 114) before the values ​​323_1~323_N of the associated performance metrics 320_1~320_N fall outside the actual threshold range 324_1~324_N by determining the fault conditions 325_1~325_N of the active operating states based on the limited threshold range.

[0083]

[0096] Referring to Figure 8, an embodiment 800 of the light source 100 (Figure 1) comprises a photogenerator 805 having two gas discharge chambers 804A and 804B, which generates a pulsed output light beam 802 directed to a lithography exposure apparatus 801. The pulsed output light beam 802 has wavelengths in the ultraviolet region (e.g., the deep ultraviolet region) used by the lithography exposure apparatus 801 to pattern a semiconductor substrate, i.e., a wafer 870. In the example in Figure 8, gas discharge chamber 804A is part of a main oscillator configured to generate a seed light beam 802s, and gas discharge chamber 804B is part of a power amplifier configured to generate an output light beam 802 from the seed light beam 802s. Each of the discharge chambers 804A and 804B is equipped with a corresponding blower 808A and 808B, each of which is configured to move a corresponding gas mixture 807A and 807B containing a gain medium from a corresponding energy source 806A and 806B within the corresponding gas discharge chambers 804A and 804B. In the example in Figure 8, the apparatus 110 is configured to control the operating speed of the two blowers 808A and 808B. Specifically, the apparatus 110 controls the blowers 808A and 808B to consume the minimum amount of energy or power during the operation of the light source 800, while ensuring that no (or at least mitigated) problems and / or failures occur within the light source 800. Other embodiments of the light source 800 are also possible.

[0084]

[0097] Each discharge chamber 804A, 804B is configured to hold the corresponding gas mixture 807A, 807B within the corresponding internal cavity 873A, 873B. The gas mixture 807A, 807B used in the corresponding discharge chambers 804A, 804B may be a combination of gases suitable for generating the corresponding light beams 802s, 802 centered on the required wavelength, bandwidth, and energy. For example, the gas mixture 807A, 807B may contain argon fluoride (ArF) emitting light with a wavelength of approximately 193 nm. Each discharge chamber 804A, 804B is defined by corresponding chamber walls 803A_1, 803A_2, 803B_1, 803B_2 configured to hold the corresponding blowers 808A, 808B and, in this embodiment, the corresponding optical components 875A, 876A, 877A, 875B, 876B, 877B. Each discharge chamber 804A, 804B houses a corresponding energy source 806A, 806B configured to supply energy to the gas mixtures 807A, 807B in their respective internal cavities 873A, 873B. For example, each energy source 806A, 806B may comprise a pair of electrodes that form a potential difference and excite the gain medium of the gas mixtures 807A, 807B when in operation.

[0085]

[0098] Each discharge chamber 804A, 804B may have one or more optical components. For example, discharge chamber 804A may have optical components 875A, 876A associated with the internal cavity 873A of discharge chamber 804A. Optical components 875A, 876A may have windows that allow the light beam to enter and exit the internal cavity 873A of discharge chamber 804A. Optical component 875A may be a partially reflective / partially transmitted optical coupler that allows the seed light beam 802s to exit discharge chamber 804A. The light source 800 may also have other optical components outside of discharge chamber 804A, such as optical component 877A corresponding to a spectral feature selection module that selects the wavelength and / or bandwidth of the seed light beam 802s output from discharge chamber 804A. For example, the spectral feature selection module 877A may have one or more beam expanding prisms or beam splitters. In this example, optical component 875A is held within chamber wall 803A_1, and optical component 876A is held within chamber wall 803A_2.

[0086]

[0099] The discharge chamber 804B includes optical components 875B and 876B associated with the internal cavity 873B of the discharge chamber 804B. The optical components 875B and 876B may have windows that allow light beams (such as seed light beam 802s and light beam 802) to enter and exit the internal cavity 873B of the discharge chamber 804B. The light source 800 may also include other optical components located outside the discharge chamber 804B, such as optical component 877B, which corresponds to a beam inverter or rotor configured to guide the light beam 802 back through the discharge chamber 804B. In the example in Figure 8, optical component 875B is held within chamber wall 803B_1 and optical component 876B is held within chamber wall 803B_2.

[0087]

[0100] During operation of the light source 800, the device 110 controls the operating speeds of the two blowers 808A and 808B. In some embodiments, the control of the operating speed of blower 808A may be independent of the control of the operating speed of blower 808B. In some embodiments, each blower 808A and 808B is controlled independently by dedicated devices (810A and 810B). Furthermore, device 810B may have a different design from device 810A, taking into account the differences in how discharge chambers 804A and 804B each affect the parameters of the output light beam. In addition, in these embodiments, the control of blowers 808A and 808B is not coupled, but simultaneous control by devices 810A and 810B may result in a different coupling in terms of performance compared to controlling only one, because each blower 808A and 808B drives vibrations within the frames of chambers 804A and 804B in a different way.

[0088]

[0101] In other embodiments, the control of the operating speed of blower 808A and / or blower 808B may depend on the photogenerator 105 and associated performance metrics, and therefore the control of the two blowers 808A and 808B may be coupled.

[0089]

[0102] In some embodiments, a single device 110 may be provided that is configured to control the blower 810A of the first discharge chamber 804A, but the device 110 is not used to control the blower 810B of the second discharge chamber 804B.

[0090]

[0103] Specifically, in the example in Figure 8, the device 110 (Figure 2) includes a monitoring module 112 that monitors fault conditions for one or more operating states of the light source 800, a decrement module 114 that appropriately reduces the operating speed of blowers 808A and 808B when the fault conditions for one or more operating states of the light source 800 are clear and the corresponding reduced operating speed of blowers 808A and 808B is equal to or greater than the baseline speed, and an increment module 116 that appropriately increases the operating speed of blowers 808A and 808B when a fault condition for one or more operating states of the light source 800 is flagged. In this way, the device 110 controls blowers 808A and 808B to consume the minimum amount of energy or power during operation of the light source 800, thereby mitigating or reducing problems and / or faults within the light source 800 based on the fault conditions of the light source 800 and the baseline speed of blowers 808A and 808B.

[0091]

[0104] Referring to Figure 9A, Embodiment 900 of the light source 100 (Figure 1) comprises a photogenerator 905 that generates a pulsed light beam 902 directed towards a lithography exposure apparatus 901, each comprising a plurality of optical oscillators 909-1 to 909-N, each having a corresponding gas discharge chamber 904-1 to 904-N, and a control system 950. The light source 900 is configured to generate an output light beam 902 in the ultraviolet region, which is used, for example, by the lithography exposure apparatus 901 to pattern a semiconductor substrate, i.e., a wafer 970. Specifically, the lithography exposure apparatus 901 exposes the wafer 970 with a shaped exposure beam 902' formed by passing the light beam 902 (which is the exposure beam in this example) through a projection optical system 995. In the example shown in Figure 9A, the photogenerator 905 comprises N optical oscillators 909_1 to 909_N, and consequently N gas discharge chambers 904-1 to 904-N (where N is an integer greater than 1). Each of the gas discharge chambers 904-1 to 904-N is configured to emit a corresponding optical beam 978-1 to 978-N toward the beam combiner 993. In the example shown, the control system 950 is connected to the photogenerator 905 and the lithography exposure apparatus 901. Other embodiments of the light source 900 are also possible.

[0092]

[0105] Each of the gas discharge chambers 904-1 to 904-N is equipped with a corresponding blower 908-1 to 908-N, and each of the blowers 908-1 to 908-N is configured to move a corresponding gas mixture 907-1 to 907-N containing a gain medium from a corresponding energy source 906-1 to 906-N within the corresponding gas discharge chamber 904-1 to 904-N. In the example of Figure 9A, device 110 (Figure 2) is provided as part of a control system 950, which is a blower controller that controls the operating speed of each of the blowers 908-1 to 908-N. Device 110 is configured to control the operating speed of the blowers 908-1 to 908-N. Specifically, device 110 controls each blower 908-1 to 908-N to consume the minimum amount of energy or electrical power during the operation of the light source 900, while ensuring that no (or at least mitigated) problems and / or failures occur within the light source 900.

[0093]

[0106] The details of optical oscillator 909-1 are discussed below. The other N-1 optical oscillators of the light generator 905 have the same or similar characteristics.

[0094]

[0107] The optical oscillator 909-1 comprises a gas discharge chamber 904-1 housing an energy source 906-1 which may include, for example, a cathode and an anode, and a blower 908-1. The discharge chamber 904-1 also includes a gas mixture 907-1 which contains a gain medium. A resonator is formed between a spectral feature selection module 977-1 located on one side of the discharge chamber 904-1 and an output coupler 980-1 located on a second side of the discharge chamber 904-1. The spectral feature selection module 977-1 may include diffractive optical elements, such as a grating and / or prisms, for fine-tuning the spectral output of the discharge chamber 904-1. In some embodiments, the spectral feature selection module 977-1 comprises multiple diffractive optical elements. For example, the spectral feature selection module 977-1 may include four prisms, some of which are configured to control the central wavelength of the optical beam 978-1, and others are configured to control the spectral bandwidth of the optical beam 978-1.

[0095]

[0108] In some embodiments, the spectral feature selection module 977-1 may include, or be in communication with, a spectral feature control system configured to control, for example, various components within the spectral feature selection module 977-1. In these embodiments, the decrement module 114 and increment module 116 of the device 110 (which in this example are part of the control system 950) may be configured to avoid interference blower operating speeds in which the aliased frequencies of the second harmonic of the blower 908-1 interfere with the spectral feature control system associated with the light source 900. For example, the interference blower operating speed may depend on the repetition rate at which the light source 900 generates the light beam (including, in this example, the light beam 902 or the exposure beam 902').

[0096]

[0109] The optical oscillator 909-1 also includes a line-centered analysis module 981-1 that receives the output optical beam from the output coupler 980-1. The line-centered analysis module 981-1 is a measurement system that can be used to measure or monitor the wavelength of the optical beam 978-1. The line-centered analysis module 981-1 can provide data to the control system 950, which can determine metrics related to the optical beam 978-1 based on the data from the line-centered analysis module 981-1. For example, the control system 950 can determine a beam quality metric or spectral bandwidth based on the data measured by the line-centered analysis module 981-1.

[0097]

[0110] The photogenerator 905 also includes a gas supply system 990 which is fluidly coupled to the discharge chamber 904-1 via a fluid tube 998. The fluid tube 998 is any conduit capable of transporting a gas or other fluid with no or minimal loss of that fluid. For example, the fluid tube 998 may be a pipe made of or coated with a material that does not react with one or more fluids transported in the conduit 998. The gas supply system 990 includes a chamber 991 which contains and / or is configured to receive a supply of one or more gases used in the gas mixture 907-1. The gas supply system 990 also includes devices (pumps, valves, and / or fluid switches) which enable the gas supply system 990 to remove gas from or inject gas into the discharge chamber 904-1. The gas supply system 990 is coupled to a control system 950. The gas supply system 990 may be controlled by the control system 950 to perform, for example, replenishment procedures.

[0098]

[0111] The other N-1 optical oscillators are similar to optical oscillator 904-1 and have similar or identical components and sub-systems. For example, each of the optical oscillators 909-1 to 909-N includes an energy source similar to energy source 906-1, a spectral feature selection module similar to spectral feature selection module 977-1, and an output coupler similar to output coupler 980-1. The optical oscillators 909-1 to 909-N may be tuned or configured so that all of the optical beams 978-1 to 978-N have the same characteristics, or the optical oscillators 909-1 to 909-N may be tuned or configured so that at least some of the optical oscillators have at least some characteristics that differ from the others. For example, all of the optical beams 978-1 to 978-N may have the same center wavelength, or the center wavelengths of each optical beam 978-1 to 978-N may be different. The central wavelength generated by a specific one of the optical oscillators 909-1 to 909-N can be set using the corresponding spectral feature selection module.

[0099]

[0112] The light generator 905 also includes a beam control device 992 and a beam combiner 993. The beam control device 992 is located between the gas mixture of the optical oscillators 909-1 to 909-N and the beam combiner 993. The beam control device 992 determines which of the optical beams 978-1 to 978-N is incident on the beam combiner 993. The beam combiner 993 forms an exposure beam 902 from one or more optical beams incident on the beam combiner 993. In the example shown, the beam control device 992 is represented as a single element. However, the beam control device 992 may be implemented as an assembly of individual beam control devices. For example, the beam control device 992 may be an assembly of shutters, with one shutter associated with each optical oscillator 909-1 to 909-N.

[0100]

[0113] The photogenerator 905 may comprise other components and systems. For example, the photogenerator 905 may comprise a beam preparation system 994 equipped with a bandwidth analysis module that measures various properties of the light beam (such as bandwidth or wavelength). The beam preparation system 994 may also comprise a pulse stretcher (not shown) that stretches each pulse interacting with the pulse stretcher in time. The beam preparation system 994 may also comprise other components that can act on light, such as reflective and / or refractive optical elements (e.g., lenses and mirrors) and / or filters. In the example shown, the beam preparation system 994 is positioned within the path of the exposure beam 902. On the other hand, the beam preparation system 994 may be located elsewhere within the light source 900. Other embodiments are also possible. For example, the photogenerator 905 may comprise N instances of the beam preparation system 994, each instance being positioned to interact with one of the light beams 978-1 to 978-N. In another example, the light generator 905 may include an optical element (such as a mirror) that directs the light beams 978-1 to 978-N toward the beam combiner 993.

[0101]

[0114] The lithography exposure apparatus 901 may be an immersion system or a dry system. The lithography exposure apparatus 901 includes a projection optics system 995 through which the exposure beam 902 passes before reaching the wafer 970, and a sensor system or metronome system 997. The wafer 970 is held or housed on a wafer holder 996. See also Figure 9B, the projection optics system 995 includes a projection objective system including a slit 995a, a mask 995b, and a lens system 995c. The lens system 995c includes one or more optical elements. The exposure beam 902 enters the lithography exposure apparatus 901, collides with the slit 995a, and at least a portion of the beam 902 passes through the slit 995a to form a shaped exposure beam 902'. In the examples of Figures 9A and 9B, the slit 995a is rectangular and shapes the exposure beam 902 into an elongated rectangular shaped light beam which is the shaped exposure beam 902'. The mask 995b includes a pattern that determines which portions of the shaping light beam are transmitted through the mask 995b and which portions are blocked by the mask 995b. Microelectronic features are formed on the wafer 970 by exposing a layer of radiation-sensitive photoresist material on the wafer 970 with an exposure beam 902'. The design of the pattern on the mask is determined by the desired specific microelectronic circuit features.

[0102]

[0115] Embodiments may be further described by the following clauses: 1. Apparatus for a light source, A monitoring module that monitors the operational status of one or more light sources, A decrement module that reduces the operating speed of a blower located in the gas discharge chamber of a light source, which moves a gas mixture containing a gain medium from an energy source that supplies energy to the gas mixture within the gas discharge chamber, when a fault condition relating to one or more operating states of the light source is clear and the reduced operating speed is equal to or greater than the baseline speed, An apparatus comprising: an increment module that increases the operating speed of a blower when a flag is set for a fault condition relating to one or more operating states of a light source. 2. The apparatus of Clause 1, wherein the baseline speed of the blower is related to the years of service of the gas discharge chamber, and the baseline speed changes as the gas discharge chamber deteriorates over time. 3. The apparatus of Clause 1, wherein each of the one or more operating states is defined by performance measurement standards relating to the light source or the light beam generated by the light source. 4. The apparatus of Clause 3, in which one or more performance metrics include a wavelength histogram associated with the light beam, an energy dose error associated with the light beam, an energy error associated with the light beam, and the operating point of the gas discharge chamber in the light source. 5. The device of Clause 3, in which a fault condition is flagged if at least one of the relevant performance metrics is not within the threshold range of that performance metric, and a fault condition is clear if all of the relevant performance metrics are within their corresponding threshold ranges. 6. The apparatus of Clause 5, wherein at least one of the operating states of the light source is active so that the operating speed of the blower is adjusted before the value of the relevant performance metric falls outside the threshold range of the performance metric, and at least one of the operating states is reactive so that the operating speed of the blower is adjusted after the value of the relevant performance metric falls outside the threshold range of the performance metric. 7. The apparatus of Clause 6, wherein each active operating state is associated with a limited threshold range that is narrower than the actual threshold range of the performance metric, and the blower's operating speed is adjusted before the value of the associated performance metric falls outside the actual threshold range by determining the fault condition of the active operating state based on the limited threshold range. 8. The apparatus of Clause 1, wherein a fault condition relating to one or more operating states of a light source is determined using a low-pass filter or a weighted sum filter. 9. The apparatus of Clause 1, wherein a decrement module reduces the operating speed of the blower by a decrement speed step size, and an increment module increases the operating speed of the blower by an increment speed step size. 10. The apparatus of clause 9, wherein the increment speed step size is greater than the decrement speed step size. 11. The apparatus of Clause 9, wherein the increment speed step size is 25 revolutions per minute (rpm) or less, and the decrement speed step size is approximately half, one-third, one-quarter, or one-fifth of the increment speed step size. 12. The device of Clause 1, wherein the operating speed of the blower is adjusted by an increment module and a decrement module within a blower speed range determined by the minimum blower speed and the maximum blower speed. 13. The apparatus of Clause 1, wherein the decrement module and increment module respectively avoid blower operating speeds in which the aliased frequency of the second harmonic of the blower interferes with the spectral feature control system associated with the light source. 14. The apparatus of Clause 13, wherein the interfering blower operating speed depends on the repetition rate at which the light source generates a light beam. 15. The apparatus of Clause 1, further comprising a baseline module for increasing the blower's operating speed when the blower's operating speed falls below the baseline speed. 16. The apparatus of Clause 1, which is a state machine for a light source, wherein the monitoring module is in a monitoring state, the decrementing module is in a decrementing state, and the incrementing module is in an incrementing state. 17. The apparatus of Clause 16, wherein after reducing the operating speed of the blower in a decrement state, the state machine transitions from a decrement state to an increment state if a fault condition relating to one or more operating states of the light source is flagged. 18. The apparatus of Clause 16, further including a baseline state in which the blower operating speed is increased when the blower operating speed falls below the baseline speed, and the apparatus transitions from a decrement state to a baseline state when the blower operating speed falls below the baseline speed. 19. The apparatus of Clause 18, wherein the baseline state increases the operating speed of the blower in the baseline state, and then the state machine transitions from the baseline state to the increment state if a fault condition relating to one or more operating states of the light source is flagged. 20. The apparatus of Clause 18, wherein the machine transitions from a monitored state to a baseline state when the blower operating speed falls below the baseline speed. 21. The apparatus of Clause 16, wherein, after increasing the operating speed of the blower in an increment state, the state machine transitions from an increment state to a monitoring state if the upward operating speed of the blower is greater than the target speed. 22. A device according to Clause 16, in which the state machine transitions from a monitoring state to an increment state when a fault condition relating to one or more operating states of a light source is flagged. 23. A device of Clause 16, in which a state machine transitions from a monitoring state to a decrement state when one or more termination criteria are met, the termination criteria being based on one or more of the baseline speed, the number of light beam pulses generated by the light source, and events that result in an improvement in the performance of the light source. 24. A blower controller for a light source, A blower positioned within a gas discharge chamber of a light source, comprising a control system in communication with the blower which moves a gas mixture containing a gain medium from an energy source that supplies energy to the gas mixture within the gas discharge chamber, wherein the control system Monitor the operational status of one or more light sources and the failure status of each light source. If the fault status for one or more operating states of the light source is clear and the reduced operating speed is equal to or greater than the baseline speed, the blower's operating speed is reduced in the decrement state. A blower controller that increases the blower's operating speed in an increment state when a flag is set for a fault condition related to one or more operating states of the light source. 25. The control system Computer-readable memory module and A blower controller according to clause 24, comprising one or more electronic processors coupled to a computer-readable memory module. 26. A blower controller according to Clause 24, wherein the fault status for one or more operating states is defined using binary, where a value of 0 is assigned to the fault status if the fault status is clear, and a value of 1 is assigned to the fault status if a flag is set. 27. A blower controller according to Clause 24, wherein the control system further increases the blower's operating speed in an increment state if the blower's decreasing operating speed falls below the baseline speed. 28. A method for controlling a blower placed in a gas discharge chamber of a light source, To monitor the operational status of one or more light sources, If the fault status for one or more operating states of the light source is clear and the reduced operating speed is equal to or greater than the baseline speed, the blower's operating speed will be decremented, and A method including incrementing the operating speed of a blower when a flag is set for a fault condition relating to one or more operating states of a light source. 29. The method of Clause 28, which includes decrementing the operating speed of the blower to reduce the amount of vibration in the light source caused by the movement of the blower. 30. The method of Clause 28, wherein decrementing the operating speed of a blower includes reducing the operating speed of the blower by a decrement speed step size, and incrementing the operating speed of a blower includes increasing the operating speed of the blower by an increment speed step size. 31. The method of clause 30, further comprising determining the increment speed step size and the decrement speed step size of a blower, each depending on a fault condition relating to one or more operating states of the light source. 32. The method of Clause 28, which includes decrementing and incrementing the blower's operating speed to adjust the blower's operating speed within a range of blower speeds defined by the minimum and maximum blower speeds. 33. The method of clause 32, further comprising determining a blower speed range of a blower that depends on a fault condition of one or more operating states of a light source. 34. The method of Clause 28, further comprising incrementing the operating speed of the blower if the reduced operating speed of the blower falls below the baseline speed. 35. The method of Clause 28, which includes monitoring failure conditions relating to one or more operating states, such that one or more termination criteria are met, and the blower's operating speed is reduced only if one or more of the termination criteria are met. 36. The method of clause 35, wherein the termination criterion is based on the baseline speed and the number of light beam pulses generated by the light source, and the termination criterion is met when the operating speed of the blower is greater than the baseline speed and the number of light beam pulses is greater than the minimum number of pulses. 37. A photogenerator comprising one or more gas discharge chambers for holding a gas mixture containing a gain medium, housing an energy source for supplying energy to the gas mixture, and generating a light beam, wherein at least one gas discharge chamber holds a blower for moving the gas mixture from the energy source within the gas discharge chamber, A device for adjusting the operating speed of a blower, A monitoring module that monitors the fault status related to the operating state of one or more light sources. A decrement module that reduces the operating speed of a blower when the fault status related to one or more operating states of the light source is clear and the reduced operating speed is equal to or greater than the baseline speed, and An ultraviolet light source comprising: a device equipped with an increment module that increases the operating speed of a blower when a fault condition in one or more operating states of the light source is flagged. 38. An ultraviolet light source according to Clause 37, wherein the gain medium emits deep ultraviolet (DUV) light in response to a voltage signal being applied to the energy source. 39. An ultraviolet light source according to Clause 38, wherein the gas gain medium comprises argon fluoride (ArF), krypton fluoride (KrF), or xenon chloride (XeCl). 40. An ultraviolet light source according to Clause 37, comprising two gas discharge chambers, each having a main oscillator for generating a seed light beam and a power amplifier for generating an output light beam from the seed light beam. 41. An ultraviolet light source according to Clause 37, wherein the light generator comprises multiple gas discharge chambers, each of which emits a light beam toward a beam combiner. 42. The device increases the blower's operating speed when the blower's reduced operating speed falls below the baseline speed, as specified in Clause 37.

[0103]

[0116] Other embodiments are within the scope of the claims.

Claims

1. A device for a light source, A monitoring module configured to monitor the failure status of one or more operating states of the light source, A decrement module is configured to reduce the operating speed of a blower, which is disposed within the gas discharge chamber of the light source, and which is configured to move the gas mixture, including a gain medium from an energy source configured to supply energy to the gas mixture, within the gas discharge chamber, when the fault condition relating to one or more operating states of the light source is clear, and the proposed new operating speed of the blower is equal to or greater than the baseline speed, and the number of pulses of the light beam generated by the gas discharge chamber since the last change in the operating speed of the blower is greater than the threshold number of pulses, An apparatus comprising: an increment module configured to increase the operating speed of the blower when a flag is set in the fault condition relating to one or more operating states of the light source.

2. The apparatus according to claim 1, wherein each of the one or more operating states is determined by a performance measurement standard relating to the light source or the light beam generated by the light source.

3. The apparatus of claim 2, wherein the one or more performance measurement criteria include a wavelength histogram associated with the light beam, an energy dose error associated with the light beam, an energy error associated with the light beam, and the operating point of the gas discharge chamber in the light source.

4. The apparatus according to claim 1, wherein the fault condition relating to one or more operating states of the light source is determined using a low-pass filter or a weighted sum filter.

5. The apparatus according to claim 1, wherein the decrement module is configured to reduce the operating speed of the blower by a decrement speed step size, and the increment module is configured to increase the operating speed of the blower by an increment speed step size.

6. The apparatus according to claim 5, wherein the increment speed step size is larger than the decrement speed step size.

7. The apparatus according to claim 1, wherein the decrement module and the increment module are each configured to avoid blower operating speeds at which the aliased frequency of the second harmonic of the blower interferes with a spectral feature control system associated with the light source.

8. The apparatus of claim 7, wherein the interfering blower operating speed depends on the repetition rate at which the light source generates a light beam.

9. The apparatus according to claim 1, further comprising a baseline module configured to increase the operating speed of the blower when the operating speed of the blower falls below the baseline speed.

10. The apparatus according to claim 1, wherein the apparatus is a state machine for the light source, wherein the monitoring module is in a monitoring state, the decrement module is in a decrement state, and the increment module is in an increment state, and after reducing the operating speed of the blower in the decrement state, the state machine transitions from the decrement state to the increment state when a flag is set for one or more fault conditions relating to the operating states of the light source.

11. The apparatus according to claim 1, wherein the apparatus is a state machine for the light source, wherein the monitoring module is in a monitoring state, the decrement module is in a decrement state, and the increment module is in an increment state, and the state machine further includes a baseline state configured to increase the operating speed of the blower when the operating speed of the blower falls below the baseline speed, and the state machine transitions from the decrement state to the baseline state when the operating speed of the blower falls below the baseline speed.

12. The apparatus of claim 11, wherein the state machine transitions from the monitoring state to the baseline state when the operating speed of the blower falls below the baseline speed.

13. The apparatus according to claim 1, wherein the apparatus is a state machine for the light source, the monitoring module is in a monitoring state, the decrement module is in a decrement state, and the increment module is in an increment state, the state machine transitions from the monitoring state to the decrement state when one or more termination criteria are met, the termination criteria being based on one or more of the baseline speed, the number of light beam pulses generated by the light source, and an event resulting in an improvement in the performance of the light source.

14. A blower controller for a light source, A control system is in communication with a blower located within the gas discharge chamber of the light source, the blower being configured to move the gas mixture, which includes a gain medium from an energy source configured to supply energy to the gas mixture, within the gas discharge chamber, wherein the control system The malfunction status of one or more operating states of the aforementioned light source is monitored. If the fault condition relating to one or more operating states of the light source is clear, and the proposed new operating speed of the blower is equal to or greater than the baseline speed, and the number of pulses of the light beam generated by the gas discharge chamber since the last time the operating speed of the blower changed is greater than the threshold pulse number, then the operating speed of the blower is reduced in the decrement state. A blower controller configured to increase the operating speed of the blower in an increment state when a flag is set for one or more of the fault conditions relating to the operating states of the light source.

15. The blower controller according to claim 14, wherein the fault status relating to one or more operating states is determined using a binary system, where a value of 0 is assigned to the fault status if the fault status is clear, and a value of 1 is assigned to the fault status if a flag is set.

16. The blower controller according to claim 14, wherein the control system is further configured to increase the operating speed of the blower in the increment state if the proposed new operating speed of the blower falls below the baseline speed.

17. An ultraviolet light source, A photogenerator comprising two or more gas discharge chambers configured to hold a gas mixture containing a gain medium, house an energy source configured to supply energy to the gas mixture, and generate a light beam, wherein at least one of the gas discharge chambers is configured to hold a blower configured to move the gas mixture from the energy source within the gas discharge chamber, and each of the gas discharge chambers is configured to emit a light beam toward a beam combiner, A device configured to adjust the operating speed of the blower, A monitoring module configured to monitor fault conditions related to one or more operating states of the ultraviolet light source, A decrement module configured to reduce the operating speed of a blower when the fault condition relating to one or more operating states of the ultraviolet light source is clear and the proposed new operating speed of the blower is equal to or greater than the baseline speed, and The apparatus includes an increment module configured to increase the operating speed of the blower when a flag is set in the fault condition of one or more operating states of the ultraviolet light source, An ultraviolet light source, wherein one or more operating states include an actuator operating point of the photogenerator that controls the relative timing between a first trigger signal transmitted to a first energy source of a first gas discharge chamber and a second trigger signal transmitted to a second energy source of a second gas discharge chamber.

18. The ultraviolet light source of claim 17, wherein the apparatus comprises a baseline module configured to increase the operating speed of the blower when the proposed new operating speed of the blower falls below the baseline speed.

19. The light source comprises a plurality of gas discharge chambers, each of which is configured to emit a light beam toward a beam combiner, The apparatus of claim 1, wherein one or more of the operating states include an actuator operating point of the light source that controls the relative timing between a first trigger signal transmitted to a first energy source of a first gas discharge chamber and a second trigger signal transmitted to a second energy source of a second gas discharge chamber.

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