Reducing power consumption for charged particle system

Abstract

To provide a method and a system that reduce power consumption of a system that includes a charged particle optic when in the standby mode by overcoming or at least alleviating the shortcomings and disadvantages of the prior art.SOLUTION: The present invention relates to a method for reducing power consumption of a charged particle system. The charged particle system includes at least one charged particle optical element, and a cooling assembly configured to cool the at least one charged particle optical element, and the method includes a step of operating the charged particle system in the standby mode, and the total power consumption of the charged particle system is reduced compared to a case of operating the charged particle system in the operational mode. Furthermore, the invention relates to respective charged particle systems.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates generally to the field of charged particle optics, and more particularly to electromagnetic lenses used, for example, in charged particle beam microscope systems. More particularly, the present invention relates to charged particle systems and methods for reducing the power consumption of the respective charged particle systems. [Background technology]

[0002] Charged particle beam microscope systems are widely used for the precise observation, characterization, and / or fabrication of microscale or nanoscale systems, e.g., samples. Due to the use of charged particles, these systems can advantageously provide higher resolution than traditional optical microscope systems, which rely on the use of light. In practice, charged particle beam microscope systems typically enable resolutions in the range of tens of pm to hundreds of nm. Such systems can be, for example, electron beam microscopes or ion beam microscopes.

[0003] Similar to conventional optical microscope systems, charged particle beam microscope systems require charged particle optics, particularly lenses, to manipulate (e.g., focus) the charged particle beam. Such charged particle optics is generally based on the action of electromagnetic fields on charged particles in the same way that optical media act on light rays. In charged particle beam microscope systems, the charged particle optics may comprise, among other things, electromagnetic lenses.

[0004] Specifically, an electromagnetic lens may include at least one electromagnetic coil, also referred to as an electromagnet or simply a coil. These systems require currents of the order of several amperes, e.g., in the range of 1-20 A, due to wiring resistance, and also introduce significant heat into the system. Thus, charged particle optics may induce thermal drift due to thermal expansion and contraction of different components of the system. Therefore, active cooling is typically provided to thermally stabilize the system and avoid thermal drift, as well as to prevent damage to the coil and / or other elements due to overheating.

[0005] However, room temperature systems utilizing charged particle optics systems require a significant amount of time to stabilize after the system, and particularly the charged particle optics, is turned on. That is, it can take hours for the system to stabilize after being turned on. Furthermore, system drift during the start-up period while the system stabilizes can cause previously made adjustments to no longer be appropriate for the system's condition. Overall, this means that the system is unavailable to the user. Therefore, current charged particle beam microscope systems are typically operated 24 hours a day, 7 days a week to ensure temperature stability and performance. In other words, since it is currently impractical to turn such systems off, it is standard for them to be on 24 / 7 to ensure performance availability.

[0006] However, a significant portion of power usage in charged particle systems utilizing charged particle optics, e.g., charged particle beam microscope systems such as transmission electron microscopes (TEMs), can be attributed to the optical system and its cooling to maintain temperature stability and performance. In other words, temperature stability and performance come at the cost of higher power consumption even when the system is not currently in use, i.e., when the system is in idle mode. Additionally, increased performance requirements typically lead to increased requirements for optical power and / or temperature stability, both of which affect optical power and cooling. Similarly, the introduction of a maximum constant power for a particular charged particle system can increase the power usage of the charged particle optics when the system is idle. In this regard, maximum constant power may refer to driving multiple coils of a charged particle optical element, e.g., a charged particle optical element, such that the power dissipation is constant regardless of the net focusing power of the charged particle optical element up to a maximum acceleration voltage of the respective charged particle system, which may be, for example, one of 120 kV, 200 kV, 300 kV, or 400 kV.

[0007] Generally, there is a need to reduce power consumption to save energy, reduce greenhouse gas equivalents, comply with regulations, and / or reduce costs. However, for the reasons provided above, it is not acceptable to simply turn off the optics (or the entire system) when not in use in order to save power. This is simply not practical and may render the system unusable.

[0008] In view of the above, it is an object of the present invention to overcome or at least mitigate the shortcomings and disadvantages of the prior art, namely to provide a method and system for reducing the power consumption of a system comprising charged particle optics when in standby mode.

[0009] These objectives are met by the present invention. Summary of the Invention

[0010] In a first embodiment, the present invention relates to a method for reducing power consumption of a charged particle system, the charged particle system comprising at least one charged particle optical element and a cooling assembly configured to cool the at least one charged particle optical element, the method comprising operating the charged particle system in a standby mode, wherein a total power consumption of the charged particle system is reduced compared to operating the charged particle system in an operational mode. That is, the method provides a standby mode for the charged particle system, which advantageously reduces total power consumption compared to a normal operational mode so as to save power / energy when the system is idle, e.g., at night and / or on weekends. In addition to saving power, another main benefit to a user may be that the method combines power savings with minimizing thermal stabilization time when switching between standby and operational modes.

[0011] Each of the at least one charged particle optical element may have a respective element temperature, and the method may further include determining a respective temperature setpoint for at least one of the at least one charged particle optical element, and operating the charged particle system in a standby mode may include reducing and / or stopping cooling of the at least one charged particle optical element and stabilizing the element temperature of each of the at least one charged particle optical element at the respective temperature setpoint. It will be understood that "the at least one charged particle optical element" should be understood as "at least one of the at least one charged particle optical element." In other words, when operating the system in a standby mode, cooling of at least one of the at least one charged particle optical element is at least reduced, and preferably stopped, while stabilizing the temperature of the at least one charged particle optical element at the respective temperature setpoint. This may advantageously allow for reduced power consumption through the cooling assembly and at least one of the at least one charged particle optical element, while ideally allowing for maintaining its temperature to reduce and / or avoid thermal drift in the system. As a result, this may further advantageously allow for a shorter period until thermal stabilization after switching from a standby mode to an operating mode. The temperature of at least one of the at least one charged particle optical element may preferably be stabilized via a current provided to said element, which may be significantly lower compared to the current provided during normal operation with cooling.

[0012] Further, in some embodiments, the method may include determining a respective temperature set point for each of the at least one charged particle optical element, reducing and / or ceasing cooling for each of the at least one charged particle optical element, and stabilizing the respective element temperature of each of the at least one charged particle optical element at the respective temperature set point, i.e., preferably cooling is reduced for all of the at least one charged particle optical element to stabilize the respective element temperature at the determined temperature set point.

[0013] It will be appreciated that stabilizing each element temperature to a respective temperature setpoint may generally allow for a certain deviation from the temperature setpoint, e.g., a range of measurement error. In particular, element temperatures may be maintained for associated charged particle optical elements such that system performance is sufficiently stable for a desired application. Specifically, stabilizing each element temperature may include maintaining each element temperature of the associated charged particle optical element within 90%-110%, preferably within 95%-105%, and more preferably within 99%-101% of the respective temperature setpoint, i.e., the respective element temperature of each of the at least one charged particle optical element whose element temperature is stabilized may be maintained accordingly.

[0014] Reducing and / or ceasing cooling of the or each of the at least one charged particle optical element may include reducing and / or ceasing, respectively, a flow of cooling fluid to the or each of the at least one charged particle optical element. That is, the cooling assembly, e.g., a chiller, may be fluid-based. The cooling fluid may be water. Generally, the cooling assembly may be configured to cool other elements of the charged particle system.

[0015] Operating the charged particle system in a standby mode may include turning off the cooling assembly. Turning off the cooling assembly may include turning off all elements of the system cooled by the cooling assembly or placing all of the elements in their respective element-specific standby modes. In other words, in some embodiments, the cooling assembly may be completely turned off when operating the system in a standby mode. This may be advantageous because it may allow for further reduction in the overall power consumption of the system. If the cooling assembly is configured to also cool other components / elements of the system, these elements may also be turned off or placed in element-specific standby modes to ensure that no damage occurs due to the cooling being turned off.

[0016] Operating the system in an operational mode may respectively include cooling at least one charged particle optical element, i.e., during the operational mode, i.e., when operating the system in the operational mode, at least one charged particle optical element may be cooled.

[0017] Operating a charged particle system in a standby mode can include the system being in a standby configuration. Additionally or alternatively, operating a charged particle system in an operational mode can include the system being in an operational configuration. That is, the system can be in a particular configuration, e.g., with respect to valve positions, on / off operational states of system components (also referred to as system elements), etc., depending on the mode in which the system is operated.

[0018] The respective temperature setpoints for the associated charged particle optical elements may be determined during the operational mode, i.e., for each of the at least one charged particle optical element for which a respective temperature setpoint is determined, the respective temperature setpoint may be determined during the operational mode. In other words, the respective temperature setpoints may be determined during the operational mode for at least one of the at least one charged particle optical elements, and in certain embodiments, it is understood that "for at least one of at least one" may also encompass "each of at least one." That is, during the operational mode, each of the charged particle optical elements is typically at a constant temperature, which is a result of the energy, e.g., current, provided to the charged particle optical element and the cooling by the cooling assembly. Typically, there may not be any active feedback loop between the cooling and the current during normal operation, e.g., as in systems known in the state of the art. Thus, the respective temperatures may be based, for example, on the respective element temperatures during normal operation. In some embodiments, they may simply correspond to the respective element temperatures or their average values.

[0019] It will be understood that any respective temperature, respective current, respective setpoint, etc. is always associated with a respective charged particle optical element. Thus, whenever reference is made to an "associated charged particle optical element," it means the charged particle optical element associated with the respective current, setpoint, temperature, etc. Specifically, the method may include, for example, determining a respective temperature setpoint for at least one of the at least one charged particle optical element, and therefore, for brevity and readability, when referring to the method steps, may be referred to as "determining a respective temperature setpoint for an associated charged particle optical element." Thus, the term "associated charged particle optical element" may refer to at least one of the at least one charged particle optical element for which a respective parameter / variable is determined. Similarly, when reference is made to a respective temperature setpoint for an associated charged particle optical element, it will be understood that it refers to the respective temperature setpoint of at least one of the at least one charged particle optical element for which a respective temperature setpoint is determined.

[0020] The respective temperature setpoints for the associated charged particle optical elements may be determined prior to operating the charged particle system in standby mode, i.e., for each of the at least one charged particle optical element for which a respective temperature setpoint is to be determined, and the respective temperature setpoints may be determined prior to operating the charged particle system in standby mode. In some embodiments, the respective temperature setpoints for the associated charged particle optical elements may be determined immediately prior to operating the charged particle system in standby mode, i.e., for each of the at least one charged particle optical element for which a respective temperature setpoint is to be determined, the respective temperature setpoints may be determined immediately prior to operating the charged particle system in standby mode. That is, the respective temperature setpoints may be determined prior to entering standby mode, preferably immediately prior to entering standby mode. This may advantageously make it possible to ensure that the respective temperature setpoints correspond to the most recent settings in the operational mode.

[0021] At least one charged particle optical element may be current-driven, and the method may include providing a respective current to each of the at least one charged particle optical element. That is, each of the at least one charged particle optical element may be provided with a respective current, and the current may be different for each of the at least one charged particle optical element. In such a case, the method may include providing a respective operating current to each of the at least one charged particle optical element when operating the system in an operating mode. That is, each of the at least one charged particle optical element may be provided with a respective operating current, which may vary among individual charged particle optical elements and may be adjusted during operation to suit specific needs, such as the focal length of an electromagnetic lens. Note that the system may further include other optical elements for charged particles that are not current-driven. However, in embodiments in which at least one charged particle optical element is current-driven, such other optical elements are not considered to be part of the at least one charged particle optical element.

[0022] The method may further include determining, during the operational mode, a respective current set point for each of the at least one charged particle optical element. The respective current set point may correspond to a respective operating current.

[0023] Stabilizing the respective element temperatures may include providing a respective standby current to the associated charged particle optical element, i.e., to each of the at least one charged particle optical element whose element temperature is stabilized. Furthermore, providing the respective standby currents may include controlling the respective standby currents provided to the associated charged particle optical elements. In other words, the standby currents may be controlled to stabilize the respective element temperatures at the respective temperature setpoints even though cooling is turned off. This may advantageously result in a significantly lower standby current compared to the operating current. Additionally, controlling the respective standby currents provided to the associated charged particle optical elements may include reducing an average current compared to operating the charged particle system in an operational mode. That is, at least, the average current provided to the at least one charged particle optical element may be reduced. Additionally or alternatively, controlling the respective standby currents provided to the associated charged particle optical elements may include reducing the average current compared to the respective operating current. The average standby current may be reduced by at least 33%, preferably at least 40%, and more preferably at least 50% compared to operating the charged particle system in an operational mode.

[0024] Controlling each standby current provided to an associated charged particle optical element may include modulating the standby current to reduce the average current supplied to the associated charged particle optical element. Furthermore, modulating each standby current may include pulse width modulation (PWM). Modulating the current may advantageously prevent the current from becoming too low if the system is not designed for it, for example, if the system is not configured to stably provide and / or measure a current below a certain threshold, such as 1 A. Through modulation, the current amplitude can be higher, but the average current is still reduced based on the duty cycle and / or switching frequency of the modulated current.

[0025] Typically, to avoid relative thermal fluctuations, i.e., thermal fluctuations exceeding 5%, preferably 1%, of the desired temperature, the current may be modulated at a switching frequency, e.g., above a few Hz. In other words, if this is the standby mode, fluctuations may be tolerated to a certain extent, but because thermal stability of the operational mode is critical to the system's performance, transitioning from standby mode to operational mode may impose stricter requirements on the allowable fluctuations. That is, while thermal fluctuations themselves may not be an issue in standby mode, it may generally be necessary to be able to return the system to a thermally stable operational mode quickly and reliably. Therefore, fluctuations in standby mode may be limited at least to a level that allows for a sufficiently fast return to a stable operational mode. Modulating each standby current may involve modulation at a switching frequency of at least 0.01 Hz, preferably at least 0.1 Hz, such as 1 Hz or 3 Hz. That is, in typical systems, modulation of the standby current may be as low as 1 / 10 Hz. More generally, however, the minimum frequency may be tied to the thermal mass (and therefore the thermal time constant) of the system. Therefore, the switching frequency may ultimately depend on the thermal mass of the system; for example, a system with a higher thermal mass than typical systems may allow for lower switching frequencies, e.g., below 0.1 Hz, potentially below 0.01 Hz.

[0026] Furthermore, modulating each standby current may include modulation with a duty cycle selected to be sufficient to reduce the average current to a desired level and maintain the effective current above the operating threshold of the electrical driver system, e.g., current source, such average current level may, for example, typically be about 2 A for the objective lens and lower for other lenses.

[0027] When operating the system in standby mode, each maximum standby current may be maintained at the respective current setpoint of the associated charged particle optical element. That is, the current setpoint of the associated charged particle optical element may be maintained when switching to standby mode, but the average current provided to the charged particle optical element may be reduced by pulse width modulation, e.g., by turning on / off a current drive / source. In other words, the current provided may still be equal to the operating current, but with modulation, the current is only provided in pulses based on the modulation of the signal so that the average current is still lower.

[0028] Modulating the respective standby currents provided may include repeatedly switching the current sources on and off, i.e., a simple form of pulse width modulation may be achieved by repeatedly switching the current sources on and off, e.g., by toggling the respective current sources / drivers on and off, e.g., at a fixed switching frequency.

[0029] The charged particle system may include a plurality of charged particle optical elements, and the method may include sequentially modulating respective standby currents to associated charged particle optical elements to reduce and / or prevent power surges. In other words, the modulation of the respective currents may be synchronized with respect to one another such that power surges are reduced, for example, by ensuring that maximum values ​​overlap as little as possible.

[0030] In the standby mode, the power consumption of the at least one charged particle optical element can be reduced compared to operating the charged particle system in an operational mode. In particular, the power consumption of the charged particle system operating in the standby mode can be reduced by at least 33%, preferably at least 40%, and more preferably at least 50% compared to operating the charged particle system in an operational mode. This reduction can be achieved by a reduced standby current compared to the operational current.

[0031] The method may further include returning the system to operation in an operational mode after operating the system in a standby mode. That is, for example, a user may indicate that the charged particle system needs to be placed back into operation, e.g., to perform measurements and / or imaging of a sample. Returning the system to operation in an operational mode may include re-establishing and / or initiating cooling of the or each of the at least one charged particle optical element. Furthermore, returning the system to operation in an operational mode may include providing a respective operating current to each of the charged particle optical elements.

[0032] Additionally or alternatively, returning the system to operation in the operational mode may include determining and indicating when each element temperature has stabilized to its respective temperature setpoint. This may take, for example, at most 10 minutes, such as at most 1 hour, preferably at most 30 minutes, and more preferably at most several minutes. Furthermore, determining when each element temperature has stabilized to its respective temperature setpoint may include determining the current element temperature of the associated charged particle optical element. That is, when switching the system from standby mode to operational mode, there may be deviations of each element temperature from its respective temperature setpoint due, for example, to thermal inertia of the charged particle system. Thus, the system may determine and indicate when the element temperature has again settled to its respective temperature setpoint. This may advantageously allow a user to know when the system is fully operational again. An indication may refer to providing a visual indication, such as, for example, a light on a screen, e.g., an LED, or a message. However, an indication may also refer, for example, to changing the value of a variable, e.g., a Boolean variable, or sending a message.

[0033] Stabilizing the element temperature of each of the associated charged particle optical elements may include determining a current element temperature of the associated charged particle optical element. That is, for each of the charged particle optical elements for which a respective element temperature is stabilized, the stabilizing may include determining a current element temperature of the associated charged particle optical element. Further, controlling the respective standby current may include comparing the current element temperature of the associated charged particle optical element to a respective temperature setpoint and adjusting the respective standby current provided based on the comparison. Additionally or alternatively, controlling the respective standby current may include determining an error between the respective temperature setpoint and the current element temperature of the associated charged particle optical element and adjusting the respective standby current provided based on the error.

[0034] Each temperature set point may be at least one of a temperature and an electrical resistance, i.e., a temperature set point may be a temperature value and / or a resistance value, since resistance also indicates a temperature based on the respective calibration measurement.

[0035] Determining the respective temperature set points for the associated charged particle optical elements may include determining the electrical resistance of the associated charged particle optical elements. That is, for each charged particle optical element for which a respective temperature set point is determined, determining the respective temperature set point may include determining the electrical resistance of the associated charged particle optical element. Additionally or alternatively, determining the respective temperature set points for the associated charged particle optical elements (i.e., for each charged particle optical element for which a respective temperature set point is determined) may include determining the temperature of the associated charged particle optical element through a dedicated measurement coil and / or thermocouple attached to or within the associated charged particle optical element. In some embodiments, determining the respective temperature set points for the associated charged particle optical elements (i.e., for each charged particle optical element for which a respective temperature set point is determined) may include determining the average temperature and / or electrical resistance of the associated charged particle optical element. Averaging the temperature or electrical resistance may advantageously allow for compensation for small fluctuations, for example, through modulated current, etc.

[0036] Generally, (average) temperature and / or resistance measurements may be repeated sufficiently to ensure that the fluctuations are within a range determined for an acceptable time for returning to operational mode after standby mode. For example, such measurements may be repeated at least every 1, 2, 3, 5, 7, or 10 minutes. Generally, however, the repetition rate may also be increased for steep temperature gradients and decreased when the temperature is relatively stable. In other words, the repetition rate may be adjusted based on the current temperature stability and / or during temperature changes, e.g., when returning to operational mode.

[0037] Typically, the average temperature and / or resistance may be determined by averaging the temperature or resistance over a measurement interval. The measurement interval may be, for example, 1 second. However, the measurement interval may be increased or decreased depending on the noise level of the measurement. In some embodiments, determining the average temperature and / or resistance of the associated charged particle optical element may include averaging the temperature and / or resistance over a period of 0.5 seconds or more to 2 seconds, such as 0.2 to 30 seconds, preferably 0.5 to 10 seconds, and more preferably 1 second.

[0038] Each temperature set point may correspond to, or an average of, the temperature and / or electrical resistance of the associated charged particle optical element during an operational mode. That is, each temperature set point may correspond to, or an average of, the temperature and / or electrical resistance of the associated charged particle optical element during an operational mode.

[0039] The current element temperature may be at least one of a temperature and an electrical resistance. Determining the current element temperature of the associated charged particle optical element may include determining its electrical resistance. Additionally or alternatively, determining the current element temperature of the associated charged particle optical element may include determining the temperature of the associated charged particle optical element through a dedicated measurement coil and / or thermocouple attached to or within the associated charged particle optical element. Determining the current element temperature of the associated charged particle optical element may include determining an average temperature and / or electrical resistance for the associated charged particle optical element.

[0040] Again, the average temperature and / or resistance may be determined by averaging the temperature or resistance over a measurement interval. The measurement interval may generally be selected so that a stable value can be obtained. Alternatively, a running average over multiple samples of shorter duration may be used. The measurement interval may be, for example, 1 second. However, the measurement interval may be increased or decreased depending on the noise level of the measurement. In some embodiments, determining the average temperature and / or resistance of the associated charged particle optical element comprises averaging the temperature and / or electrical resistance over a period of 0.5 seconds to 2 seconds, such as 0.2 to 30 seconds, preferably 0.5 seconds to 10 seconds, and more preferably 1 second.

[0041] As mentioned above, the repetition rate may generally be selected to be sufficient to ensure that the measurement is within a determined range of acceptable times for returning to operational mode after standby mode. For example, such measurements may be repeated at least every 1, 2, 3, 5, 7, or 10 minutes. However, the repetition rate may be increased for steep temperature gradients and decreased when the temperature is relatively stable. In other words, the repetition rate may be adjusted based on the current temperature stability and / or the presence of steep temperature gradients. In some cases, the repetition rate may also be adjusted due to, for example, using a moving average of shorter samples, where an increased repetition rate may be desirable.

[0042] Determining the respective temperature set points may include determining a respective individual temperature set point for each of the associated charged particle optical elements. That is, for each charged particle optical element for which a respective temperature set point is determined, determining the respective temperature set point may include determining an individual temperature set point. The individual temperature set points may be independent of, but are not necessarily different from, the respective temperature set points of other charged particle optical elements.

[0043] Each current set point may correspond to, or an average of, the current provided to the associated charged particle optical element during an operational mode.

[0044] The method may further include using at least one safety measure when operating the system in standby mode to prevent overheating of the at least one charged particle optical element. The at least one safety measure may include setting a maximum current threshold and limiting each standby current provided to an associated charged particle optical element to at most the maximum current threshold. The maximum current threshold may be set individually for each associated charged particle optical element. That is, the maximum current threshold may be set individually for each charged particle optical element to which a respective standby current is provided. Alternatively, the maximum current threshold may be set to the same value for all of the at least one charged particle optical element. The maximum current threshold may be in the range of 5% to 70%, preferably 10% to 50%, and more preferably 10% to 30% of the operating current.

[0045] At least one safety measure may include setting a maximum resistance threshold and limiting each standby current provided to an associated charged particle optical element so that the electrical resistance of the current-driven charged particle optical element is at most the maximum resistance threshold. The maximum resistance threshold may be set individually for each associated charged particle optical element. That is, the maximum resistance threshold may be set individually for each charged particle optical element to which a respective standby current is provided. Alternatively, the maximum resistance threshold may be set to the same value for all of the at least one charged particle optical element. The maximum resistance threshold may be at most 150%, preferably 130%, of the resistance of the associated charged particle optical element at 20°C. For example, the maximum resistance threshold for each associated charged particle optical element may be 130% of the R20 value for that element, where R20 is the resistance of the element at an ambient temperature of 20°C.

[0046] The standby current provided to each associated charged particle optical element may range from 5% to 70%, preferably 10% to 50%, of the operating current when the system is operating in standby mode. When the system is operating in operating mode, the current provided to at least one charged particle optical element may exceed 1 A.

[0047] The method may include scheduling a standby time for automatically switching the charged particle system from operating in an operational mode to operating in a standby mode. Additionally or alternatively, the method may include scheduling an operating time for automatically switching the charged particle system from operating in a standby mode to operating in an operational mode. Furthermore, scheduling an operating time for automatically switching the charged particle system from operating in a standby mode to operating in an operational mode may include stabilizing each component temperature to a respective temperature setpoint prior to the scheduled operating time. This may, for example, advantageously allow for scheduling a time during which the system automatically operates in standby mode while ensuring it can return to operational status as needed. For example, the system may automatically switch to standby mode during periods when it is not typically in use, such as at night and / or on weekends. Of course, it will be understood that such automatic scheduling may be overrideable by a user, for example, when working outside of working hours.

[0048] At least one charged particle optical element may be an electromagnetic lens. Further, the electromagnetic lens may comprise a coil. It will be appreciated that the electromagnetic lens may comprise more than one coil, for example, a plurality of coils.

[0049] The charged particle system may be a charged particle beam microscope system. Further, the charged particle system may be an electron microscope. The electron microscope may be a scanning electron microscope. Alternatively, the electron microscope may be a transmission electron microscope. Further, the transmission electron microscope may be a scanning transmission electron microscope.

[0050] The method may include driving at least one of the at least one charged particle optical element such that power dissipation is constant regardless of net focusing power of the respective charged particle optical element across all acceleration voltages up to a maximum acceleration voltage of the charged particle system when operating in an operational mode. The maximum acceleration voltage may be, for example, one of 120 kV, 200 kV, 300 kV, or 400 kV. This may also be referred to as "maximum constant power" because power dissipation is kept constant across the Hall acceleration voltage range of the respective system.

[0051] The method may be computer-implemented, i.e. the method may advantageously be carried out on a computer, e.g. a processing device, that controls a system in accordance with the method described above.

[0052] Operating the charged particle system in standby mode may include a standby transition period before stabilizing the respective element temperatures. That is, very generally, at the start of operation of the system in standby mode, there may be a transition period before the respective element temperatures stabilize, e.g., after switching off cooling and reducing current due to thermal inertia of at least one charged particle optical element. The method may further include ramping down the respective currents provided to the associated charged particle optical elements from their operating currents to their standby currents during the standby transition period. Furthermore, the ramp down may be selected to compensate for the thermal inertia of the associated optical elements and / or their cooling. That is, the thermal inertia of the optical elements in combination with the provided cooling, e.g., the thermal inertia of the cooling fluid, may be compensated for. For example, the ramp down rate may be selected to compensate for the thermal inertia. Additionally or alternatively, the progression of the current ramp may be selected to compensate for the thermal inertia; for example, the ramp may follow a linear progression, a polynomial progression, and / or an exponential progression, or a combination thereof, and the slope may also be adjusted accordingly. Such a current ramp may allow for reducing and / or avoiding temperature fluctuations during the standby transition period and / or shortening the standby transition period.

[0053] Returning the system to operation in the operational mode may include an operational transition period, and the method may further include ramping up the respective currents to the respective operational currents during the operational transition period. Furthermore, the ramp-up may be selected to compensate for the thermal inertia of the associated optical elements and / or their cooling. That is, the thermal inertia of the optical elements in combination with the provided cooling may be compensated for, for example, the thermal inertia of the cooling fluid. Similarly, such current ramping may advantageously reduce and / or avoid temperature fluctuations during the operational transition period and / or shorten the operational transition period.

[0054] Determining the electrical resistance and / or average electrical resistance may include determining a voltage resulting from a given current provided to an associated charged particle optical element. That is, to determine the electrical resistance, a voltage for a known current may be determined, e.g., measured. It will be appreciated that the relationship between current, voltage, and resistance allows the resistance to be determined.

[0055] In another embodiment, the invention relates to a computer program product comprising instructions which, when executed by a computer, cause the computer to carry out the method described above.

[0056] In a further embodiment, the present invention relates to a charged particle system comprising at least one charged particle optical element and a cooling assembly configured to cool the at least one charged particle optical element, wherein the at least one charged particle optical element can be current-driven.

[0057] The system can be configured to have at least two configurations: an operational configuration and a standby configuration. In the operational configuration, the system can be operated in an operational mode, and in the standby configuration, the system can be operated in a standby mode. In the operational configuration, the at least one charged particle optical element can be cooled by a cooling assembly. In contrast, in the standby configuration, at least one of the at least one charged particle optical element can be less or not cooled by the cooling assembly. Preferably, in the standby configuration, each of the at least one charged particle optical element can be less or not cooled by the cooling assembly. The configuration of the system can relate to, for example, valve positions, on / off states of system components / elements, set points, etc.

[0058] In the operating configuration, each of the at least one charged particle optical element may be provided with a respective operating current. Furthermore, in the standby configuration, at least one of the at least one charged particle optical element may be provided with a respective standby current that is, at least on average, lower than the operating current. This may advantageously make it possible to reduce power consumption in the standby mode and thus the overall power consumption over the lifetime of the system. Preferably, at least one of the at least one charged particle optical element that is less or not cooled by the cooling assembly is provided with a respective standby current that is, at least on average, lower than the operating current in the standby configuration. Further preferably, in the standby configuration, each of the at least one charged particle optical element may be provided with a respective standby current that is, at least on average, lower than the operating current.

[0059] In the operating configuration, each of the at least one charged particle optical element may be at a respective operating temperature. The respective operating temperature may define a respective temperature setpoint for each of the at least one charged particle optical element. In the standby configuration, at least one of the at least one charged particle optical element may be stabilized at a respective temperature setpoint. This may advantageously allow for reducing and / or avoiding thermal drift. Preferably, in the standby configuration, at least one of the at least one charged particle optical element that is less or not cooled by the cooling assembly and / or at least one of the at least one charged particle optical element that is provided with a respective standby current that is at least on average lower than the operating current may be stabilized at a respective temperature setpoint. More preferably, in the standby configuration, each of the at least one charged particle optical element may be stabilized at a respective temperature setpoint.

[0060] The system may be configured to perform the methods described above, i.e. the system comprises means for performing the respective method.

[0061] The system may include a control unit. The control unit may be configured to perform the methods described above. In some embodiments, the control unit may include a processing device. The processing device may be configured to perform the methods described above. The processing device may be at least one of a microprocessor, a CPU, a GPU, or an FPGA, or a combination thereof.

[0062] The system may include multiple charged particle optical elements. Additionally or alternatively, at least one charged particle optical element may be an electromagnetic lens. The electromagnetic lens may include a coil. It will be appreciated that the electromagnetic lens may also include more than one coil, for example, multiple coils.

[0063] Each of the at least one charged particle optical element may have a respective element temperature. The system may be configured to determine an electrical resistance and / or a temperature of each of the at least one charged particle optical element. The determined electrical resistance and / or temperature is indicative of the respective element temperature.

[0064] At least one of the at least one charged particle optical element may include a thermocouple configured to provide a signal indicative of the respective element temperature. Additionally or alternatively, at least one of the at least one charged particle optical element may include a dedicated measurement coil to provide a signal indicative of the respective element temperature.

[0065] The system may be configured to determine the electrical resistance of at least one of the at least one charged particle optical element. In some embodiments, the system may be configured to determine the electrical resistance of each of the at least one charged particle optical element. The determined electrical resistance may be indicative of the respective element temperature relative to a respective temperature setpoint. Again, the resistance may be determined through determining, e.g., measuring, a voltage relative to a known current.

[0066] The system may include at least one closed-loop control system configured to stabilize a respective element temperature of at least one of the at least one charged particle optical element at a respective temperature setpoint. In some embodiments, the system may include a closed-loop control system configured to stabilize a respective element temperature at a respective temperature setpoint of each of the at least one charged particle optical element. The closed-loop control system may be a PID controller. For example, the closed-loop control system may control a standby current provided to an associated charged particle optical element based on a current element temperature and the respective temperature setpoint to stabilize the respective element temperature at the temperature setpoint.

[0067] The system may include at least one pulse-width-modulation (PWM) controller for providing a modulated current. Again, such modulation may be advantageous, for example, when the amplitude of the standby current is lower than that of an otherwise configured system.

[0068] The system may be provided with physical and / or virtual buttons for changing the configuration adopted by the system, which may advantageously allow a user to deliberately change the configuration adopted by the system and / or the mode in which the system is operating.

[0069] The charged particle system may be a charged particle beam microscope system. Further, the charged particle system may be an electron microscope. The electron microscope may be a scanning electron microscope. Alternatively, the electron microscope is a transmission electron microscope. Further, the transmission electron microscope may be a scanning transmission electron microscope.

[0070] The cooling assembly may be configured to provide a flow of cooling fluid. Further, the cooling fluid may be water. In the standby configuration, the cooling assembly may provide a reduced flow of cooling fluid to at least one of the at least one charged particle optical element. Preferably, in the standby configuration, the cooling assembly may provide a reduced flow of cooling fluid to at least one of the at least one charged particle optical element that may be less or not cooled by the cooling assembly, may be provided with a respective standby current that is at least on average lower than the operating current, and / or stabilized to a respective temperature setpoint. Further preferably, in the standby configuration, the cooling assembly may provide a reduced flow of cooling fluid to each of the at least one charged particle optical element. Additionally or alternatively, in the standby configuration, the cooling assembly may not provide a flow of cooling fluid to at least one of the at least one charged particle optical element. Preferably, in the standby configuration, the cooling assembly does not provide a flow of cooling fluid to at least one of the at least one charged particle optical element that may be less or not cooled by the cooling assembly, may be provided with a respective standby current that is at least on average lower than the operating current, and / or stabilized to a respective temperature setpoint. More preferably, in the standby configuration, the cooling assembly does not provide a flow of cooling fluid to each of the at least one charged particle optical element. In some embodiments, in the standby configuration, the cooling assembly may provide a reduced flow of cooling fluid to any system component. Furthermore, in the standby configuration, the cooling assembly may not provide a flow of cooling fluid to any system component.

[0071] The system may include a charged particle source, which may be an electron source, such as an electron gun.

[0072] The system may further comprise a detector. The detector may be a charge-coupled device. In some embodiments, the cooling assembly may further be configured to cool the detector. The detector may include a detector standby mode. Furthermore, the detector may be configured so that it does not require cooling when in the detector standby mode.

[0073] The system may include at least one power supply unit (PSU), and the at least one charged particle optical element may be connected to at least one of the at least one power supply unit.

[0074] The system may be configured to drive at least one of the at least one charged particle optical element such that power dissipation is constant regardless of the net focusing power of the respective charged particle optical element across accelerating voltages up to a maximum accelerating voltage of the system, which may be, for example, one of 120 kV, 200 kV, 300 kV, or 400 kV. This may also be referred to as "maximum constant power" because power dissipation is held constant across the Hall accelerating voltage range of the respective system.

[0075] The charged particle system of the described method can be the system described above.

[0076] In another embodiment, the present invention relates to the use of the described particle system according to the method described above.

[0077] The invention is also defined by the following numbered embodiments:

[0078] In the following, method embodiments are discussed. These embodiments are abbreviated by the letter "M" followed by a number. These embodiments are meant whenever reference is made herein to "method embodiments."

[0079] M1. A method for reducing power consumption in a charged particle system, the charged particle system comprising at least one charged particle optical element and a cooling assembly configured to cool the at least one charged particle optical element, the method comprising: A method comprising operating a charged particle system in a standby mode, wherein a total power consumption of the charged particle system is reduced compared to operating the charged particle system in an operational mode. M2. Each of the at least one charged particle optical element has a respective element temperature; the method further comprising determining a temperature set point for at least one of the at least one charged particle optical element; Operating the charged particle system in a standby mode reducing and / or ceasing cooling of the at least one charged particle optical element; stabilizing an element temperature of each of the at least one charged particle optical element at a respective temperature set point. M3. The method determining a respective temperature set point for each of the at least one charged particle optical element; reducing and / or stopping cooling of each of the at least one charged particle optical element; stabilizing a respective element temperature of each of the at least one charged particle optical element at a respective temperature set point. M4. A method according to an embodiment of method M2 or M3, wherein stabilizing each element temperature comprises maintaining each element temperature of the corresponding charged particle optical element within 90% to 110%, preferably within 95% to 105%, and more preferably within 99% to 101%, of its respective temperature set point. M5. A method according to any of the embodiments of methods M2-M4, wherein reducing and / or ceasing cooling of the or each of the at least one charged particle optical element comprises reducing and / or ceasing flow of cooling fluid to the or each of the at least one charged particle optical element, respectively. M6. The method according to an embodiment of the method of M5, wherein the cooling fluid is water. M7. The method according to any of the embodiments of methods M1-M6, wherein the cooling assembly is further configured to cool other elements of the charged particle system. M8. The method according to any of the embodiments of methods M1-M7, wherein operating the charged particle system in a standby mode includes turning off a cooling assembly. M9. A method according to an embodiment of the method of M8, wherein turning off the cooling assembly includes turning off all elements of the system cooled by the cooling assembly or placing all such elements in a standby mode specific to each element. M10. The method of any of the embodiments of methods M1-M9, wherein operating the system in an operational mode includes cooling at least one charged particle optical element, respectively. M11. The method of any of the method embodiments of M1-M10, wherein operating the charged particle system in a standby mode includes the system adopting a standby configuration. M12. The method of any of the method embodiments of M1-M11, wherein operating the charged particle system in an operational mode includes the system adopting an operational configuration. M13. A method according to any of the method embodiments of M1 to M12 and having the features described in M2, wherein the respective temperature set points for the associated charged particle optical elements are determined during the operational mode. M14. A method according to any of the embodiments of methods M1 to M13 and having the features described in M2, wherein respective temperature set points for associated charged particle optical elements are determined prior to operating the charged particle system in standby mode. M15. A method according to an embodiment of the method of M14, wherein each temperature setpoint for an associated charged particle optical element is determined immediately prior to operating the charged particle system in standby mode. M16. A method according to any of the embodiments of methods M1-M15, wherein at least one charged particle optical element is current-driven, the method comprising providing a respective current to each of the at least one charged particle optical element. That is, each of the at least one charged particle optical element may be provided with a respective current, and the current may be different for each of the at least one charged particle optical element. M17. A method according to an embodiment of the method of M16, wherein the method includes providing a respective operating current to each of the at least one charged particle optical element when operating the system in the operating mode. M18. A method according to an embodiment of the method of M16 or M17, further comprising determining, during the operational mode, a respective current set point for each of the at least one charged particle optical element. M19. A method according to an embodiment of the method of M18 and having the features described in M17, wherein each current set point corresponds to a respective operating current. M20. A method according to any of the embodiments of methods M16-M19 and having the features described in M2, wherein stabilizing each element temperature includes providing a respective standby current to the associated charged particle optical element. M21. A method according to an embodiment of the method of M20, wherein providing each standby current includes controlling each standby current provided to an associated charged particle optical element. M22. A method according to an embodiment of the method of M21, wherein controlling each standby current provided to an associated charged particle optical element includes reducing the average current compared to operating the charged particle system in an operational mode. That is, at least the average current provided to the at least one charged particle optical element is reduced. M23. A method according to an embodiment of the method of M21 or M22, and having the features described in M17, wherein controlling the respective standby currents provided to the associated charged particle optical elements comprises reducing the average currents compared to the respective operating currents. M24. A method according to any of the embodiments of methods M21-M23, wherein controlling each standby current provided to an associated charged particle optical element comprises modulating the standby current to reduce the average current supplied to the associated charged particle optical element. M25. A method according to an embodiment of the method of M24, wherein modulating each standby current comprises pulse width modulation (PWM). M26. A method according to an embodiment of the method of M24 or M25, wherein modulating the respective standby current comprises modulating at a switching frequency of at least 0.01 Hz, preferably at least 0.1 Hz, such as 1 Hz or 3 Hz. M27. A method according to any of the embodiments of methods M24-M26 and having the features described in M18, wherein when the system is operated in standby mode, the respective maximum standby currents are maintained at the respective current set points of the associated charged particle optical elements. That is, the current setpoint of each of the associated charged particle optical elements may be maintained when switching to standby mode, but the average current provided to the charged particle optical elements is reduced by pulse width modulation, for example, by turning on / off the current drive / source. M28. A method according to any of the embodiments of methods M24-M27, wherein modulating the respective standby current provided comprises repeatedly switching a current source on and off. That is, a simple form of pulse width modulation may be achieved by repeatedly switching current sources on and off, for example, by toggling each current source / driver on and off, at a fixed switching frequency. M29. A method according to any of the embodiments of methods M24-M28, wherein the charged particle system comprises a plurality of charged particle optical elements, and the method includes sequentially modulating the standby current to each associated charged particle optical element to reduce and / or prevent power surges. M30. A method according to any of the embodiments of methods M1-M29, wherein in a standby mode, power consumption of at least one charged particle optical element is reduced compared to operating the charged particle system in an operational mode. M31. The method of any of the method embodiments of methods M1-M30, wherein the method further comprises returning the system to operation in an operational mode after operating the system in a standby mode. M32. A method as recited in an embodiment of the method of M31 and having the features as recited in M2, wherein returning the system to operation in the operational mode includes re-establishing and / or initiating cooling of the or each of the at least one charged particle optical element. M33. A method as recited in an embodiment of the method of M31 or M32, and having the features recited in M17, wherein returning the system to operation in the operational mode includes providing a respective operating current to each of the charged particle optical elements. M34. A method according to any of the embodiments of methods M31-M33 and having the features described in M2, wherein returning the system to operation in the operational mode includes determining and indicating when each element temperature has stabilized at its respective temperature setpoint. M35. A method according to an embodiment of the method of M34, wherein determining when each element temperature has stabilized to a respective temperature setpoint includes determining a current element temperature of an associated charged particle optical element. M36. A method according to any of the embodiments of methods M1 to M35 and having the features described in M2, wherein stabilizing the element temperature of each of the associated charged particle optical elements includes determining the current element temperature of the associated charged particle optical element. M37. A method as recited in an embodiment of the method of M36 and having the features recited in M21, wherein controlling each standby current includes comparing a current element temperature of an associated charged particle optical element with a respective temperature set point and adjusting the provided respective standby current based on the comparison. M38. A method as recited in an embodiment of the method of M36 or M37, and having the feature recited in M21, wherein controlling each standby current includes determining an error between a respective temperature setpoint and a current element temperature of the associated charged particle optical element, and adjusting the provided respective standby current based on the error. M39. A method according to any of the embodiments of methods M1-M38 and having the features described in M2, wherein each temperature set point is at least one of temperature and electrical resistance. M40. A method according to any of the method embodiments of M1 to M39, and having the features described in M2 and M16, wherein determining the respective temperature set points for the associated charged particle optical elements includes determining the electrical resistance of the associated charged particle optical elements. M41. A method according to any of the embodiments of methods M1-M40, and having the features described in M2, wherein determining the respective temperature set points for the associated charged particle optical elements comprises determining the temperature of the associated charged particle optical elements through dedicated measurement coils and / or thermocouples attached to or within the associated charged particle optical elements. M42. A method according to any of the embodiments of methods M1 to M41 and having the features described in M2, wherein determining the respective temperature set points for the associated charged particle optical elements comprises determining the average temperature and / or electrical resistance of the associated charged particle optical elements. M43. A method according to an embodiment of the method of M42, wherein determining the average temperature and / or resistance of the associated charged particle optical element comprises averaging the temperature and / or electrical resistance over a period of 0.5 seconds to 2 seconds, such as 0.2 to 30 seconds, preferably 0.5 seconds to 10 seconds, more preferably 1 second. M44. A method according to any of the embodiments of methods M1 to M43 and having the features according to M2, wherein each temperature set point corresponds to, or an average of, the temperature and / or electrical resistance of the associated charged particle optical element during an operational mode. M45. A method according to any of the method embodiments of M1-M44 and having the features according to M35 and / or M36, wherein the current element temperature is at least one of temperature and electrical resistance. M46. A method according to any of the embodiments of methods M1 to M45, and having the features described in M16 and M35 and / or M36, wherein determining the current element temperature of the associated charged particle optical element comprises determining its electrical resistance. M47. A method according to any of the method embodiments of M1 to M46 and having the features described in M35 and / or M36, wherein determining the current element temperature of the associated charged particle optical element comprises determining the temperature of the associated charged particle optical element through a dedicated measurement coil and / or thermocouple attached to or within the associated charged particle optical element. M48. A method according to any of the embodiments of methods M1 to M47, and having the features described in M35 and / or M36, wherein determining the current element temperature of the associated charged particle optical element comprises determining an average temperature and / or electrical resistance for the associated charged particle optical element. M49. A method according to an embodiment of the method of M48, wherein determining the average temperature and / or resistance of the associated charged particle optical element comprises averaging the temperature and / or electrical resistance over a period of 0.5 seconds to 2 seconds, such as 0.2 to 30 seconds, preferably 0.5 seconds to 10 seconds, more preferably 1 second. M50. A method according to any of the method embodiments of M1 to M49, and having the features described in M2, wherein determining each temperature set point includes determining an individual temperature set point for each associated charged particle optical element. M51. A method according to any of the embodiments of methods M1-M50 and having the features described in M18, wherein each current set point corresponds to, or an average of, the current provided to the associated charged particle optical element during an operational mode. M52. A method according to any of the embodiments of methods M1-M51, wherein the method includes using at least one safety measure when operating the system in standby mode to prevent overheating of at least one charged particle optical element. M53. A method as recited in an embodiment of the method of M52 and having the features recited in M20, wherein at least one safety measure includes setting a maximum current threshold and limiting each standby current provided to an associated charged particle optical element to at most that maximum current threshold. M54. A method according to an embodiment of the method of M53, wherein the maximum current threshold is set individually for each associated charged particle optical element. M55. A method according to an embodiment of the method of M54, wherein the maximum current threshold is set to the same value for all of the at least one charged particle optical element. M56. A method according to any of the embodiments of methods M53 to M55, and having the features described in M17, wherein the maximum current threshold is in the range of 5% to 70%, preferably 10% to 50%, more preferably 10% to 30% of the operating current. M57. A method according to any of the embodiments of methods M52 to M56 and having the features described in M20, wherein at least one safety measure comprises setting a maximum resistance threshold and limiting the standby current provided to each associated charged particle optical element such that the electrical resistance of that current-driven charged particle optical element is at most the maximum resistance threshold. M58. A method according to an embodiment of the method of M57, wherein the maximum resistance threshold is set individually for each associated charged particle optical element. M59. A method according to an embodiment of the method of M58, wherein the maximum resistance threshold is set to the same value for all of the at least one charged particle optical element. M60. The method according to any of the embodiments of methods M57-M59, wherein the maximum resistance threshold is at most 150%, preferably 130%, of the resistance of the associated charged particle optical element at 20°C. M61. A method according to any of the embodiments of methods M1 to M60, and having the features described in M20 and M17, wherein the standby current provided to each associated charged particle optical element is in the range of 5% to 70%, preferably 10% to 50%, of the operating current when the system is operating in standby mode. M62. A method according to any of the embodiments of methods M1 to M61 and having the features described in M16, wherein when the system is operated in the operational mode, each current provided to at least one charged particle optical element is greater than 1 A. M63. A method according to any of the embodiments of methods M1 to M62 and having the features described in M22, wherein the average standby current is reduced by at least 33%, preferably at least 40%, more preferably at least 50% compared to operating the charged particle system in operational mode. M64. A method according to any of the embodiments of methods M1-M63, wherein the power consumption of the charged particle system operating in standby mode is reduced by at least 33%, preferably at least 40%, more preferably at least 50% compared to operating the charged particle system in operational mode. M65. A method according to any of the embodiments of methods M1-M64, wherein the method includes scheduling a standby time for automatically switching the charged particle system from operating in an active mode to operating in a standby mode. M66. A method according to any of the embodiments of methods M1-M65, wherein the method includes scheduling an operating time for automatically switching the charged particle system from operating in a standby mode to operating in an operating mode. M67. A method according to an embodiment of the method of M66, wherein scheduling an operating time for automatically switching the charged particle system from operating in a standby mode to operating in an operating mode includes stabilizing each element temperature to a respective temperature setpoint prior to the scheduled operating time. M68. The method according to any of the embodiments of methods M1-M67, wherein at least one charged particle optical element is an electromagnetic lens. M69. A method according to an embodiment of the method of M68, wherein the electromagnetic lens comprises a coil. M70. The method according to any of the embodiments of methods M1-M69, wherein the charged particle system is a charged particle beam microscope system. M71. The method according to any of the embodiments of methods M1-M70, wherein the charged particle system is an electron microscope. M72. The method according to any one of the embodiments of the method of M71, wherein the electron microscope is a scanning electron microscope. M73. The method according to any one of the embodiments of the method of M72, wherein the electron microscope is a transmission electron microscope. M74. The method according to any one of the preceding methods, wherein the transmission electron microscope is a scanning transmission electron microscope. M75. The method according to any of the method embodiments of M1-M74, wherein the method is computer-implemented. M76. The method of any of the embodiments of methods M1-M75, wherein operating the charged particle system in a standby mode includes a standby transition period before stabilizing the respective component temperatures. M77. A method as recited in an embodiment of the method of M76, and having the features recited in M17 and M20, wherein the method further includes ramping down respective currents provided to associated charged particle optical elements from their respective operating currents to their respective standby currents during a standby transition period. M78. A method according to an embodiment of the method of M77, wherein the ramp-down is selected to compensate for the thermal inertia of the associated optical element and / or its cooling. M79. A method according to any of the embodiments of methods M1-M78 and having the features described in M31, wherein returning the system to operation in the operational mode includes an operational transition period, the method further comprising ramping up the respective currents to the respective operational currents during the operational transition period. M80. A method according to an embodiment of the method of M79, wherein the ramp-up is selected to compensate for the thermal inertia of the associated optical element and / or its cooling. M81. A method according to any of the method embodiments of M1-M80, and having at least one feature as described in M40, M42, M46, and M48, wherein determining the electrical resistance and / or average electrical resistance comprises determining a voltage resulting from a given current provided to an associated charged particle optical element. M82. A method according to any of the embodiments of methods M1-M81 and having the features described in M16, including driving at least one of the at least one charged particle optical element such that the power dissipation is constant independent of the net focusing power of the respective charged particle optical element across all acceleration voltages up to a maximum acceleration voltage of the charged particle system when operating in the operational mode.

[0080] In the following, computer program embodiments are discussed. These embodiments are abbreviated by the letter "C" followed by a number. These embodiments are meant whenever reference is made herein to "computer program embodiments."

[0081] C1. A computer program product comprising instructions that, when the program is executed by a computer, cause the computer to perform a method according to any of the preceding method embodiments.

[0082] In the following, reference will be made to embodiments of a charged particle system. These embodiments will be abbreviated by the letter "S" followed by a number. Whenever reference is made herein to "embodiments of a system," these embodiments are meant.

[0083] S1. A charged particle system, at least one charged particle optical element; a cooling assembly configured to cool at least one charged particle optical element. S2. A charged particle system according to the system embodiment of S1, wherein at least one charged particle optical element is current driven. S3. The charged particle system of any embodiment of the system of S1 or S2, wherein the system is configured to have at least two configurations: an operating configuration and a standby configuration. S4. A charged particle system according to the system embodiment of S3, wherein in the operational configuration, the system operates in operational mode, and in the standby configuration, the system operates in standby mode. S5. The charged particle system of any one of the system embodiments of S3 or S4, wherein in an operational configuration, at least one charged particle optical element is cooled by a cooling assembly. S6. A charged particle system according to any of the system embodiments of S3-S5, wherein in a standby configuration, at least one of the at least one charged particle optical element is less cooled or not cooled by the cooling assembly. S7. The charged particle system of any of the system embodiments of S3-S6, wherein in a standby configuration, each of the at least one charged particle optical element is less or not cooled by the cooling assembly. S8. A charged particle system according to any of the system embodiments of S3 to S7 and having the features described in S2, wherein in an operating configuration, each of the at least one charged particle optical element is provided with a respective operating current. S9. The charged particle system of the system embodiment of S8, wherein in the standby configuration, at least one of the at least one charged particle optical element is provided with a respective standby current that is at least on average lower than the operating current. S10. A charged particle system according to the system embodiment of S8 or S9 and having the features described in S6, wherein in the standby configuration, at least one of the at least one charged particle optical element that is less or not cooled by the cooling assembly is provided with a respective standby current that is at least on average lower than the operating current. S11. The charged particle system of the system embodiment of S10, wherein in the standby configuration, each of the at least one charged particle optical element is provided with a respective standby current that is at least on average lower than the operating current. S12. A charged particle system according to any of the system embodiments of S1 to S11 and having the features described in S3, wherein in an operational configuration, each of the at least one charged particle optical element is at a respective operational temperature. S13. The charged particle system of the system embodiment of S12, wherein the respective operating temperatures define respective temperature set points for each of the at least one charged particle optical element. S14. The charged particle system of the system embodiment of S13, wherein in a standby configuration, at least one of the at least one charged particle optical element is stabilized to a respective temperature setpoint. S15. A charged particle system according to an embodiment of the system of S13 or S14 and having features according to S6 or S11, wherein in a standby configuration, at least one of the at least one charged particle optical element that is less or not cooled by the cooling assembly and / or at least one of the at least one charged particle optical element that is provided with a respective standby current that is at least on average lower than the operating current is stabilized at a respective temperature setpoint. S16. The charged particle system of any of the system embodiments of S13-S15, wherein in the standby configuration, each of the at least one charged particle optical element is stabilized to a respective temperature setpoint. S17. The charged particle system of any of the system embodiments S1-S16, wherein the system is configured to perform a method according to any of the preceding method embodiments. That is, the system comprises means for carrying out each method. S18. The charged particle system of any of the system embodiments S1-S17, wherein the system comprises a control unit. S19. The charged particle system of the system embodiment of S18, wherein the control unit is configured to perform a method according to any of the preceding method embodiments. S20. A charged particle system according to an embodiment of the system of S18 or S19, wherein the control unit comprises a processing device. S21. The charged particle system of the system embodiment of S20, wherein the processing device is configured to perform a method according to any of the preceding method embodiments. S22. The charged particle system of any one of the system embodiments of S20 or S21, wherein the processing device is at least one of a microprocessor, a CPU, a GPU, or an FPGA, or a combination thereof. S23. The charged particle system of any of the system embodiments of S1-S22, wherein the system comprises a plurality of charged particle optical elements. S24. The charged particle system of any of the system embodiments of S1-S23, wherein at least one charged particle optical element is an electromagnetic lens. S25. The charged particle system of an embodiment of the system of S24, wherein the electromagnetic lens comprises a coil. S26. The charged particle system of any of the system embodiments of S1-S25, wherein each of the at least one charged particle optical element has a respective element temperature. S27. The charged particle system of any of the system embodiments of S1-S26, wherein the system is configured to determine an electrical resistance and / or a temperature of each of the at least one charged particle optical element. S28. A charged particle system according to the system embodiment of S27 and having the features of S26, wherein the determined electrical resistance and / or temperature indicates the respective element temperature. S29. A charged particle system having the features of any of the system embodiments of S1-S28 and of S26, wherein at least one of the at least one charged particle optical element comprises a thermocouple configured to provide a signal indicative of the respective element temperature. S30. A charged particle system according to any of the system embodiments of S1 to S29 and having the features according to S26, wherein at least one of the at least one charged particle optical elements is provided with a dedicated measurement coil to provide a signal indicative of the respective element temperature. S31. The charged particle system of any of the system embodiments of S1-S30, wherein the system is configured to determine an electrical resistance of at least one of the at least one charged particle optical element. S32. The charged particle system of any of the system embodiments of S1-S31, wherein the system is configured to determine an electrical resistance of each of the at least one charged particle optical element. S33. A charged particle system according to the system embodiment of S31 or S32 and having the features of S26, wherein the determined electrical resistance indicates the respective element temperature relative to the respective temperature setpoint. S34. A charged particle system according to any of the system embodiments of S1 to S33 and having the features described in S26, wherein the system comprises at least one closed-loop control system configured to stabilize a respective element temperature of at least one of the at least one charged particle optical element at a respective temperature setpoint. S35. A charged particle system having the features of any of the system embodiments of S1-S34 and of S26, wherein the system comprises a closed-loop control system configured to stabilize the respective element temperatures at the respective temperature setpoints of each of the at least one charged particle optical element. S36. The charged particle system of any one of the system embodiments of S34 or S35, wherein the closed loop control system is a PID controller. S37. The charged particle system of any of the system embodiments of S1-S36, wherein the system comprises at least one pulse width modulation (PWM) controller for providing a modulated current. S38. The charged particle system of any of the system embodiments of S1-S37, wherein the system comprises physical and / or virtual buttons for changing the configuration adopted by the system. S39. The charged particle system of any of the system embodiments of S1-S38, wherein the charged particle system is a charged particle beam microscope system. S40. The charged particle system of the system embodiment of S39, wherein the charged particle system is an electron microscope. S41. The charged particle system of the system embodiment of S40, wherein the electron microscope is a scanning electron microscope. S42. The charged particle system of the system embodiment of S41, wherein the electron microscope is a transmission electron microscope. S43. The charged particle system of the system embodiment of S42, wherein the transmission electron microscope is a scanning transmission electron microscope. S44. The charged particle system of any of the system embodiments of S1-S43, wherein the cooling assembly is configured to provide a flow of cooling fluid. S45. The charged particle system of any one of the system embodiments of S44, wherein the cooling fluid is water. S46. A charged particle system having the features described in any of the system embodiments of S1-S45 and described in S3, wherein in a standby configuration, the cooling assembly provides a reduced flow of cooling fluid to at least one of the at least one charged particle optical element. S47. The charged particle system of the system embodiment of S46, wherein a reduced flow of cooling fluid is provided to at least one of the charged particle optical elements of at least one of system embodiments S6, S9, or S14. S48. A charged particle system having the features described in any of the system embodiments of S1 to S47 and described in S3, wherein in a standby configuration, the cooling assembly provides a reduced flow of cooling fluid to each of at least one charged particle optical element. S49. A charged particle system according to any of the system embodiments of S1 to S48 and having the features described in S3, wherein in a standby configuration, the cooling assembly does not provide a flow of cooling fluid to at least one of the at least one charged particle optical element. S50. The charged particle system of the system embodiment of S49, wherein in a standby configuration, the cooling assembly does not provide a flow of cooling fluid to at least one of the charged particle optical elements of at least one of system embodiments S6, S9, or S14. S51. A charged particle system having the features described in any of the system embodiments of S1 to S50 and described in S3, wherein in a standby configuration, the cooling assembly does not provide a flow of cooling fluid to each of the at least one charged particle optical element. S52. A charged particle system having the features described in any of the system embodiments of S1-S51 and described in S3, wherein in a standby configuration, a cooling assembly provides a reduced flow of cooling fluid to any system component. S53. A charged particle system according to any of the system embodiments of S1-S52 and having the features described in S3, wherein in a standby configuration, the cooling assembly does not provide a flow of cooling fluid to any system component. S54. The charged particle system of any of the system embodiments of S1-S53, wherein the system comprises a charged particle source. S55. The charged particle system of any embodiment of the system of S54, wherein the charged particle source is an electron source, such as an electron gun. S56. The charged particle system of any of the system embodiments of S1-S55, wherein the system further comprises a detector. S57. The charged particle system of any embodiment of the system of S56, wherein the detector comprises a charge-coupled device (CCD). S58. The charged particle system of any one of the system embodiments of S56 or S57, wherein the cooling assembly is further configured to cool the detector. S59. The charged particle system of any of the system embodiments of S55-S58, wherein the detector comprises a detector standby mode. S60. The charged particle system of an embodiment of the system of S59, wherein the detector is configured to not require cooling when in the detector standby mode. S61. A charged particle system according to any of the system embodiments of S1 to S60 and having the features described in S2, wherein the system comprises at least one power supply unit (PSU) and at least one charged particle optical element is connected to at least one of the at least one power supply unit. S62. A charged particle system according to any of the system embodiments of S1 to S61 and having the features described in S2, wherein the system is configured to drive at least one of the at least one charged particle optical element such that power dissipation is constant independent of the net focusing power of the respective charged particle optical element across acceleration voltages up to a maximum acceleration voltage of the system. M83. The method according to any one of the method embodiments of M1-M82, wherein the charged particle system is a system according to any one of the preceding system embodiments.

[0084] In the following, reference will be made to embodiments of use. These embodiments will be abbreviated by the letter "U" followed by a number. Whenever reference is made in this specification to "embodiments of use," these embodiments are meant.

[0085] U1. Use of a charged particle system according to any of the system embodiments of S1 to S62 in any of the method embodiments of M1 to M83. [Brief explanation of the drawings]

[0086] [Figure 1a] 1 depicts the kWh consumption of an exemplary TEM system. [Figure 1b] 1 depicts the associated kWh consumption of an exemplary TEM system. [Figure 2a] 1 illustrates a schematic representation of a charged particle system. [Figure 2b] 1 is a schematic representation of a transmission electron microscope. [Figure 3] 1 depicts one embodiment of the method according to the present invention. [Figure 4] 2 depicts another embodiment of the method according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0087] It should be noted that not all drawings have all reference numbers. Instead, in some drawings, some reference numbers have been omitted for brevity and ease of illustration. Embodiments of the present invention will now be described with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and are not intended to be limiting. For clarity, some features may be shown in only some figures, while other features may be omitted. However, omitted features may exist, and features shown and discussed need not be present in all embodiments.

[0088] There is a need to reduce power consumption in all kinds of areas to save energy, reduce greenhouse gas equivalents, comply with regulations, and / or reduce costs. However, with charged particle systems such as TEMs, it is currently difficult to save energy because shutting down the system comes at the cost of thermal drift and misalignment of the system due to system cooling, and stabilization times of several hours until everything is properly aligned and stable.

[0089] As can be seen from FIGS. 1a and 1b, the largest portion of a typical TEM system's energy consumption comes from the optical power supply unit (PSU), i.e., the charged particle optical elements and the cooling assembly, also referred to as a chiller. Specifically, FIG. 1a depicts the kWh consumption of an exemplary TEM system broken down by different system components. The total energy consumption is approximately 12 kWh in this example. FIG. 1b depicts the relative contributions of the system components to the total energy consumption. It can be seen that the PSU of the charged particle optical elements combined with the cooling assembly accounts for 67% of the total energy consumption of the exemplary TEM system. As a result, these two components have been identified as having the greatest potential for energy savings when the system is idle, i.e., not in use. Furthermore, the energy consumption of the cooling assembly is primarily dependent on the PSU of the charged particle optical elements and, more generally, on the energy consumption of the charged particle optical elements.

[0090] In other words, based on analysis of an exemplary system, it has been found that a significant portion of the power usage in a TEM microscope can be attributed to the optical system and its cooling (via water) to maintain temperature stability and performance. That is, the optics and stabilization via cooling assemblies, e.g., chillers, primarily use power. While the above analysis has been performed for a specific system, the same applies to other charged particle systems. Briefly, it is desirable for the system's (over-life) power usage (and greenhouse gas equivalents) to be able to turn off the charged particle optical elements during system idle times while still maintaining at least some degree of thermal stability, which allows the system to return to full operation within a significantly shorter amount of time compared to starting up from a completely off state.

[0091] In view of the above findings, the present invention is directed to a charged particle system and a corresponding method that allows reducing the power consumption of the charged particle system. That is, the basic concept is to avoid or minimize thermal drift by not turning off the power completely, but to reduce the power consumption while keeping the charged particle optical elements at the same temperature. Thus, briefly summarized, a standby mode is provided by turning off the cooling, e.g., water cooling, of the charged particle optical elements, but still providing sufficient current to the charged particle optical elements to maintain their temperature.

[0092] Referring to FIG. 2a, a very basic example of a charged particle system 1 according to the present invention is schematically depicted, comprising at least one charged particle optical element 11 and a cooling assembly 12 configured to cool the at least one charged particle optical element. The system is further configured to have at least two configurations: an operational configuration and a standby configuration. Typically, at least one charged particle optical element 11 is current-driven. As such, the charged particle optical element may be connected to a power supply unit. In some embodiments, multiple charged particle optical elements 11 may share a power supply unit (PSU), e.g., all charged particle optical elements 11 may share a single power supply unit (PSU), which may be configured to provide individual respective currents to the charged particle optical elements 11. In other embodiments, each charged particle optical element 11 may be connected to an individual PSU.

[0093] The charged particle system 1 can be, for example, an electron microscope, e.g., a charged particle beam microscope system such as a scanning electron microscope (SEM), a transmission electron microscope (TEM), or a scanning transmission electron microscope (STEM). In particular, the charged particle system can also relate to a TEM system for life science, material science, and / or semiconductors. FIG. 2b schematically depicts a transmission electron microscope, e.g., comprising an electron source 14, also referred to as an electron gun 14 (more generally, a charged particle source 14), for providing an electron beam, and a number of electromagnetic lenses 11, 11A-11D, which can be, for example, a condenser lens system, a diffractive lens, an objective lens, a projection lens, etc. Furthermore, the TEM can comprise a sample 16, or more generally, a sample port for providing a sample, and a detector 18, such as a CCD.

[0094] Those skilled in the art will understand that the charged particle system 1, and in particular also the TEM, may comprise further components not depicted in Figures 2a and 2b, such as a vacuum system, a control unit, etc. That is, Figures 2a and 2b do not necessarily depict all system components, but rather focus on the components relevant to the present invention and their understanding.

[0095] When such a charged particle system 1 is in an operating configuration, at least one charged particle optical element 11, e.g., at least one electromagnetic lens 11, 11A-11D, may be cooled by a cooling assembly 12. The cooling assembly may provide a flow of cooling fluid, e.g., water, to each of the cooled components and may additionally include, for example, a detector 18. Additionally, each of the at least one charged particle optical element 11, 11A-11D may be provided with a respective operating current. The operating current may be a current required for normal operation of the charged particle system 1. Each operating current may lead to heating of the corresponding charged particle optical element, which may be offset by cooling the cooling assembly such that each of the at least one charged particle optical element 11, 11A-11D may be at a respective operating temperature. Specifically, the temperature of each of the charged particle optical elements 11, 11A-11D may stabilize / settle to a respective operating temperature such that the charged particle system is thermally stable and thermal drift is at least significantly reduced, or preferably avoided. Each operating temperature may therefore define a temperature set point for at least one charged particle optical element 11, 11A-11D.

[0096] In contrast, when a charged particle system 1, such as a TEM, is in a standby configuration, at least one or all of the at least one charged particle optical element 11, 11A-11B are less or not cooled by the cooling assembly. Therefore, the flow of coolant to the at least one charged particle optical element 11, 11A-11B may be reduced or turned off entirely. To offset the reduced (or no) cooling of each charged particle optical element 11, 11A-11D, a respective standby current is provided that is, at least on average, lower than the operating current. Specifically, the temperature of at least one or each of the charged particle optical elements 11, 11A-11D is stabilized at a respective temperature setpoint. Very generally, this can be achieved by controlling the respective standby current provided. Temperature stabilization, and therefore control of the standby current, can be provided by a closed-loop control system, e.g., a PID controller.

[0097] The respective standby currents may be pulse-width modulated so that they are at least on average lower than the respective operating currents. In this regard, the charged particle system 1 (also simply referred to as system 1) may include a pulse-width modulation (PWM) controller.

[0098] In some embodiments, system 1 may include physical and / or virtual buttons, e.g., software buttons, for changing the configuration adopted by the system, i.e., system 1 may include a button that allows a user to switch the system from an operational configuration to a standby configuration.

[0099] Very generally, the system 1 may be configured to perform the method according to the invention, as further described below. The system 1 may comprise a control unit (e.g., a PC), which may comprise a processing device such as a microprocessor, a CPU, a GPU, or an FPGA. The control unit and / or the processing device may be configured to perform the method according to the invention.

[0100] Very generally, a method for reducing power consumption of a charged particle system 1 comprising at least one charged particle optical element 11, 11A-11D and a cooling assembly 12 configured to cool the at least one charged particle optical element 11, 11A-11D includes step 22 of operating the charged particle system 1 in a standby mode, wherein the total power consumption of the charged particle system 1 is reduced compared to operating the charged particle system 1 in an operational mode.

[0101] With reference to FIG. 3, the method may include step 211 of determining a respective temperature set point for each of the at least one charged particle optical element 11, 11A-11D, step 22 of operating the charged particle system 1 in a standby mode, wherein the total power consumption of the charged particle system 1 is reduced compared to operating the charged particle system 1 in an operational mode, step 221 of reducing and / or stopping cooling of at least one of the at least one charged particle optical element when the system 1 is operated in the standby mode, and step 222 of stabilizing the respective element temperature of the at least one of the at least one charged particle optical element (also referred to as the associated charged particle element) at the respective temperature set point.

[0102] In other words, a respective temperature set point may be determined for each of the at least one charged particle optical element, preferably before entering standby mode, i.e., in operation mode (step 211). That is, a respective temperature set point may be determined for each of the at least one charged particle optical element 11, 11A-11D, e.g., an individual temperature set point for each of the at least one charged particle optical element. Determining the respective temperature set point may include determining the temperature, electrical resistance, average temperature, and / or average electrical resistance of the associated charged particle optical element.

[0103] Very generally, the resistance of a charged particle optical element can be determined by determining / measuring the voltage produced by a given current. The resistance can generally be a measure of the temperature of the charged particle optical element, which can be determined by utilizing the resistance of the charged particle optical element calibrated at a known temperature and applying the respective thermal coefficient of the conductive material of the charged particle optical element, e.g., copper, across the difference.

[0104] Operating the system in standby mode (step 221) may include reducing and / or stopping cooling of at least one, preferably each, of the at least one charged particle optical element. In other words, cooling of at least one charged particle optical element 11, 11A-11D, preferably at least one of the at least one charged particle optical element 11, 11A-11D, may be reduced and / or stopped, preferably stopped. This may include reducing and / or stopping the flow of cooling fluid to at least one of the at least one charged particle optical element. In some embodiments, the cooling assembly may be turned off entirely if all elements cooled by the cooling assembly can be accommodated. In embodiments in which the cooling assembly 12 is further configured to cool other elements of the charged particle system 1, these elements may also be turned off or placed in their own standby mode.

[0105] The chiller of an exemplary TEM system, such as the TEM system from which the measurements of Figures 1a and 1b are provided, can be estimated to remove approximately 3-4 kW of heat through the cooling fluid, e.g., water. Thus, when turning off the water cooling of the charged particle optics in such a system, the dissipation of the optics can be reduced by this amount while maintaining the same temperature, and an additional savings of approximately 1-2 kW (based on chiller efficiency) is also achieved because less cooling power needs to be provided to the chiller.

[0106] Furthermore, operating the system in standby mode may also include stabilizing the element temperature of each of the at least one charged particle optical element for which cooling is reduced and / or stopped at a respective temperature setpoint. This may typically occur simultaneously with step 221. That is, when operating the system in operational mode (step 22), steps 221 and 222 may typically be performed simultaneously. In particular, steps 221 and 222 are included in step 22, that is, these steps may be considered substeps of step 22 of the method.

[0107] Very generally, the method may include operating system 1 in an operational mode (step 21) and operating the system in a standby mode (step 22). Operating system 1 in a standby mode may include system 1 adopting a standby configuration, and operating system 1 in an operational mode may include system 1 adopting an operational configuration.

[0108] As discussed above with respect to the embodiment of system 1, at least one charged particle optical element 11, 11A-11D may preferably be current-driven, and thus the method may include providing a respective current to each of the at least one charged particle optical element 11, 11A-11D, where the provided current may be different for each of the at least one charged particle optical element. The current may be provided by a respective PSU to which the at least one charged particle optical element is connected. For example, each of the charged particle optical elements may be connected to an individual PSU, or multiple (e.g., all) charged particle optical elements may be connected to a single PSU configured to individually provide a respective current to each of the charged particle optical elements.

[0109] 3, when the system is operated in an operational mode, a respective operating current may be provided to each of the at least one charged particle optical element 11, 11A-11D (step 212). Further, during the operational mode, i.e., while the system is operating in the operational mode, a respective current set point may be determined for each of the at least one charged particle optical element (step 213). The respective current set point may correspond to a respective operating current.

[0110] Again, it will be understood that steps 211, 212, and 213 are included in step 21, i.e., they represent substeps of step 21 that may, for example, be performed simultaneously.

[0111] 2, again, stabilizing the respective element temperatures 222 may include providing a respective standby current to at least one, preferably each, of the at least one charged particle optical element, which may be controlled such that the average current is reduced compared to operating the charged particle system in an operational mode, or in other words, compared to the respective operational current.

[0112] Specifically, the current element temperature of each / associated charged particle optical element may be determined, for example, through a measurement of electrical resistance (also simply referred to as resistance) or through a dedicated temperature sensor, and compared to the respective temperature setpoint. Based on this comparison, the respective standby current provided may be adjusted. The comparing may include, among other things, determining an error between the respective temperature setpoint and the current element temperature, and adjusting the respective standby current based on the error. In some cases, an average temperature or electrical resistance may be determined when determining the current element temperature and / or the respective temperature setpoint. In particular, the current element temperature of the associated charged particle optical element and the respective temperature setpoint may refer to a temperature and / or an electrical resistance.

[0113] In other words, the electrical resistance of at least one current-driven charged particle optical element can be measured as a measure of temperature, and this value can be used as a respective temperature setpoint for controlling the respective current provided to the at least one charged particle optical element when entering standby mode. The resistance of the charged particle optical element is advantageously already measured in known charged particle systems for overheat protection during normal use, for example, using a software routine. Thus, for example, the software routine can be configured to record and use the resistance (or average resistance) as a temperature setpoint to drive the respective current of the charged particle optical element when entering standby mode, while the cooling of the charged particle optical element is preferably turned off. Advantageously, the respective current provided in standby mode can be significantly reduced when the cooling is turned off, while the corresponding charged particle optical element stabilizes to its respective temperature setpoint. The respective current can be reduced, for example, by at least 33%.

[0114] The dedicated temperature sensor may be, for example, a dedicated measurement coil and / or a thermocouple. Such a dedicated sensor may advantageously allow a more robust and / or simpler implementation to be achieved.

[0115] In some embodiments, controlling the respective standby currents may include modulating the provided current. This may be particularly beneficial when only a very small standby current is otherwise required, which may be difficult to read / control. Through current modulation, a higher current may be applied to the coil for a limited amount of time. In other words, the provided current may be modulated so that the respective standby currents are modulated to be lower, on average, than the operating current. Such modulation may lead to slight variations in the temperature of the respective / associated charged particle optical elements, e.g., one or more coils, but this variation becomes known based on the duty cycle of the modulation, which may enable selecting the correct resistance value for determining the temperature of the charged particle optical elements. For example, a current of at least 1 ampere may be required to determine the resistance of a current-driven charged particle optical element, e.g., a coil, with sufficient accuracy. Thus, for example, if the respective standby currents are lower than 1 ampere to stabilize the respective element temperatures, modulation may advantageously still enable accurate resistance determination. The current modulation may include pulse-width modulation (PWM), also referred to as duty cycle modulation.

[0116] When modulating the respective standby currents, the maximum value of the modulated current, i.e., the portion during "on", can be maintained at the respective current setpoint of the operational mode. Naturally, modulation results in a lower average standby current. Thus, in a very simplified variant, the PSU units can essentially be switched on / off while the current provided in the "on" state is maintained at the current setpoint of the operational mode.

[0117] To reduce and / or prevent power surges when modulating the standby current of each of the multiple charged particle optical elements, the standby currents of each may be modulated sequentially. That is, the modulation of each standby current may be adjusted in such a way that the maximum values ​​of different standby currents occur at different times to reduce the overall maximum power required. Such modulation may be characterized by its switching frequency and / or duty cycle, similar to known methods for powering up a system.

[0118] In some embodiments, the method may further include using at least one safety measure when operating the system in standby mode to prevent overheating of the at least one charged particle optical element. For example, a maximum current threshold and / or a maximum resistance threshold may be set to limit the respective standby current. These thresholds may be set individually for each of the at least one charged particle optical element (without excluding any charged particle optical element having the same threshold), or alternatively, such thresholds may be set to the same value for all of the at least one charged particle optical element. Providing such thresholds may be particularly advantageous because it is necessary to ensure machine safety even during standby mode. In this regard, in current charged particle systems, charged particle optical elements may be operated only when cooling fluid is flowing, i.e., when interlocks may be present. However, entering standby mode requires overriding such protection, thus requiring the establishment of other measures for the safety of the system and, in particular, the charged particle optical elements.

[0119] Furthermore, it should be noted that in some embodiments, operating the charged particle system in a standby mode includes a standby transition period before stabilizing the respective component temperatures. That is, an initial standby transition period may occur when switching from operation in an operational mode to operation in a standby mode. During the standby transition period, the respective currents provided to at least one charged particle optical element may be ramped down from an operational current to a respective standby current. Preferably, the ramp down is selected to compensate for the thermal inertia of the respective optical element.

[0120] Overall, the method may thereby enable reduced power consumption of at least one charged particle optical element and cooling assembly compared to operating the charged particle system in operational mode. However, because temperatures are stabilized to their respective temperature setpoints, thermal drift is at least reduced, if not avoided, and the system stabilizes significantly faster after returning to operation in operational mode compared to turning the system 1 off and on again. For example, average standby current may be reduced by at least 33%, preferably at least 40%, and more preferably at least 50%, compared to operating the charged particle system in operational mode. Similarly, power consumption when operating the charged particle system in standby mode may be reduced by at least 33%, preferably at least 40%, and more preferably at least 50%, compared to operating the charged particle system in operational mode.

[0121] With reference to Figure 4, the method may further include returning the system to operation in an operational mode after operating the system in the standby mode, step 23. As shown in Figure 4, once the system is again operating in the operational mode (step 21), the system may be switched back to operation in the standby mode (step 22). Returning the system to operation in the operational mode may include an operational transition period, during which the respective currents provided to the at least one charged particle optical element are ramped up to the respective operating currents. The ramp-up may be selected / configured to compensate for the thermal inertia of the respective optical element.

[0122] Step 23 of operating the system again in the operational mode may include re-establishing and / or initiating cooling of at least one charged particle optical element and / or providing a respective operating current to each of the charged particle optical elements. In other words, when the system returns from the standby mode, cooling is restored and the respective currents provided to the charged particle optical elements are restored to their normal drive methods and applied levels. Step 23 may further include determining and indicating when each element temperature has stabilized to its respective temperature setpoint. This may take, for example, up to 1 hour, preferably up to 30 minutes, more preferably up to 10 minutes, such as several minutes.

[0123] In some embodiments, an automatic nighttime routine for switching between standby mode and return may be provided, which can be disabled for users working beyond their shift hours. This may also be done so that the system is ready for use by the required time, i.e., warms up and stabilizes, and therefore returns to operation in the operational mode quickly enough to compensate for the time required for full stabilization in the operational mode. In other words, the method may include scheduling a standby time for automatically switching the charged particle system from operation in the operational mode to operation in the standby mode. Furthermore, the method may include scheduling an operation time for automatically switching the charged particle system from operation in the standby mode to operation in the operational mode. Furthermore, scheduling an operation time for automatically switching the charged particle system from operation in the standby mode to operation in the operational mode may include stabilizing the temperature of each element prior to the scheduled operation time. In other words, after exiting standby mode, the system may warm up and indicate normal operation only when the temperature (resistance) of the charged particle optical elements, e.g., coil temperature, stabilizes. This means that after a request to resume normal operation after operating in standby mode, the temperature of the charged particle optical elements, e.g., coil resistance, can be observed and the system will only indicate this to the user if it is at a normal operating value (recorded before entering standby mode).

[0124] The disclosed methods may be computer-implemented, i.e., the methods may be performed by a processing unit, a computer, and / or a control unit that executes the methods and thereby controls the charged particle system.

[0125] Therefore, the present invention provides a charged particle system and method that allows for reduced power consumption when the system is idle, i.e., not being used by a user, without the disadvantage of requiring several hours for the system to stabilize after being switched on. Based on Figures 1a and 1b, it is estimated that a power reduction of 4.6 kW can be saved by reducing the power consumption of the charged particle optical elements and cooling assembly. Considering the average operating time of the charged particle system, i.e., imaging, this may allow for a reduction in annual energy consumption of 18-25%.

[0126] In other words, approximately 3-4 kW of heat can be wasted in the cooling fluid. Therefore, a standby mode is provided, in which the fluid flow to at least one charged particle optical element is turned off, but their temperature is maintained by using the desired temperature as a setpoint (respective temperature setpoint), e.g., the coil resistance of the electromagnetic lens, and the respective current provided to the at least one charged particle optical element is used as a variable, i.e., controlled. Without cooling, this results in a significantly lower current than in the operating mode, resulting in a reduction in power. When the particle current system is returned to the operating mode, cooling is re-established and the provided current is returned to the normal current drive, i.e., the operating current.

[0127] Overall, the provided method and system may enable a standby mode that offers substantial power savings, yet still allow the user to switch back to operational mode without having to let the system settle for several hours. That is, rather than requiring a cold start, the system allows the charged particle optical elements to stabilize in temperature, and preferably at their operating temperature, even in standby mode, so that system stability can be achieved much faster when switching back to operational mode due to the method / system stabilizing the temperature of the charged particle optical elements and simultaneously turning off cooling.

[0128] Whenever relative terms such as "about," "substantially," or "approximately" are used herein, such terms should also be construed to include the exact terms. That is, for example, "substantially straight" should also be construed to include "exactly straight."

[0129] Whenever steps are recited above or further in the appended claims, it should be noted that the order in which the steps are recited in this text may be accidental. That is, unless otherwise specified or apparent to one of ordinary skill in the art, the order in which the steps are recited may be accidental. That is, if the specification describes, for example, that a method includes steps (A) and (B), this does not necessarily mean that step (A) precedes step (B); step (A) may be performed (at least partially) simultaneously with step (B), or step (B) may precede step (A). Furthermore, if step (X) is described as preceding another step (Z), this does not mean that there are no steps between step (X) and step (Z). That is, step (X) preceding step (Z) encompasses the situation in which step (X) is performed immediately before step (Z), but also encompasses the situation in which step (X) is performed before one or more steps (Y1), ..., that follow step (Z). Corresponding considerations apply when terms such as "after" or "before" are used.

[0130] Although a preferred embodiment has been described above with reference to the accompanying drawings, those skilled in the art will understand that this embodiment is provided for illustrative purposes only and should not be construed in any way as limiting the scope of the present invention as defined by the claims.

Claims

1. 1. A method for reducing power consumption in a charged particle system, comprising: the charged particle system comprising: at least one charged particle optical element; and a cooling assembly configured to cool the at least one charged particle optical element; The method includes operating the charged particle system in a standby mode, wherein a total power consumption of the charged particle system is reduced compared to operating the charged particle system in an operational mode. method.

2. each of the at least one charged particle optical element having a respective element temperature; The method further includes determining a temperature set point for each of at least one of the at least one charged particle optical element; Operating the charged particle system in the standby mode comprises: reducing and / or stopping the cooling of the at least one charged particle optical element; and stabilizing the element temperature of each of the at least one charged particle optical element at the respective temperature set point. The method of claim 1.

3. 3. The method of claim 1, wherein the at least one charged particle optical element is current-driven, the method comprising providing a respective current to the at least one charged particle optical element.

4. stabilizing the respective element temperatures includes providing a respective standby current to an associated charged particle optical element; providing the respective standby currents includes controlling the respective standby currents provided to the associated charged particle optical elements. A method according to claim 3 and having the features according to claim 2.

5. 5. The method of claim 4, wherein controlling the respective standby currents provided to the associated charged particle optical elements comprises reducing an average current compared to operating the charged particle system in the operational mode.

6. stabilizing the element temperature of each of the associated charged particle optical elements includes determining a current element temperature of the associated charged particle optical element; controlling the respective standby currents includes comparing the current element temperatures of the associated charged particle optical elements to the respective temperature set points and adjusting the provided respective standby currents based on the comparison.

6. The method according to claim 4 or 5.

7. 7. The method of claim 5, wherein controlling the respective standby currents provided to the associated charged particle optical elements comprises modulating the standby currents to reduce the average current supplied to the associated charged particle optical elements.

8. 8. The method according to claim 1, wherein the power consumption of the charged particle system operating in the standby mode is reduced by at least 33%, preferably at least 40%, more preferably at least 50% compared to operating the charged particle system in the operational mode.

9. The method according to any one of claims 1 to 8, wherein the at least one charged particle optical element is an electromagnetic lens.

10. The method according to any one of claims 1 to 9, wherein the charged particle system is a charged particle beam microscope system.

11. 1. A charged particle system comprising: at least one charged particle optical element; a cooling assembly configured to cool the at least one charged particle optical element; the charged particle system is configured to have at least two configurations: an operating configuration and a standby configuration; Charged particle systems.

12. the at least one charged particle optical element is current-driven; In the operating configuration, each of the at least one charged particle optical element is provided with a respective operating current; in the standby configuration, at least one of the at least one charged particle optical element is provided with a respective standby current that is at least on average lower than the operating current; The charged particle system of claim 11 .

13. in the operating configuration, each of the at least one charged particle optical element is at a respective operating temperature; the respective operating temperatures defining respective temperature set points for each of the at least one charged particle optical element; and wherein in the standby configuration, at least one of the at least one charged particle optical element is stabilized to the respective temperature setpoint.

13. The charged particle system according to claim 11 or 12.

14. in the operating configuration, the at least one charged particle optical element is cooled by the cooling assembly; in the standby configuration, at least one of the at least one charged particle optical element is less or not cooled by the cooling assembly; The charged particle system according to any one of claims 11 to 13.

15. Charged particle system according to any one of claims 11 to 14, wherein the system is configured to carry out a method according to any one of claims 1 to 10.

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