Optical system, lithography apparatus and method for condition monitoring

Abstract

An optical system (200) of a lithography apparatus (1) for condition monitoring in the optical system (200, 300), comprising a first module (202, 210) having a first module control device (204), the first module (202, 210) being able to be monitored on the basis of at least one first system observable; a second module (206, 210) having a second module control device (208), the second module (206, 210) being able to be monitored on the basis of at least one second system observable; and a system control device (216) configured to take a first error code (214) as a basis for performing at least one control function for the optical system (200) and / or the lithography apparatus (1), and to receive condition monitoring information (218) of the first and / or the second module (202, 206, 210), and, based on the condition monitoring information (218) of the first and / or the second module (202, 206, 210), to generate a second error code (220) that provides a system condition monitoring compared to the first error code (214).

Description

[0001] Carl Zeiss SMT GmbH

[0002] 1

[0003] OPTICAL SYSTEM, LITHOGRAPHY APPARATUS AND METHOD FOR CONDITION MONITORING

[0004] This invention relates to an optical system of a lithography apparatus for condition monitoring in the optical system, a lithography apparatus having such an optical system and a method for condition monitoring in such an optical system and / or a lithography apparatus.

[0005] The content of the priority application DE 10 2024209 120.0 is incorporated by reference in its entirety.

[0006] Microlithography is used to produce microstructured structural elements, for example integrated circuits. The microlithography process is performed using a lithography apparatus that comprises an illumination system and a projection system. The image of a mask (reticle) illuminated by means of the illumination system is projected by means of the projection system onto a substrate, for example a silicon wafer, which is coated with a light-sensitive layer (photoresist) and is arranged in the image plane of the projection system, in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0007] Driven by the need for ever smaller structures in the production of integrated circuits, EUV lithography apparatuses that use light at a wavelength in the range from 0.1 nm to 30 nm, in particular 13.5 nm, are currently under development. Since most materials absorb light at this wavelength, such EUV lithography apparatuses require the use of reflective optical units, i.e. mirrors, instead of refractive optical units, i.e. lens elements, as used previously.

[0008] In order to be able to return lithography apparatuses or individual apparatus modules at the end customer's site to the operating condition, to maintain them or to replace them in the event of a fault, it is necessary to perform diagnostics on Carl Zeiss SMT GmbH

[0009] 2 the lithography apparatuses and the apparatus modules in order to be thus able to define and execute service measures for restoring the affected functionalities if necessary.

[0010] To minimize the time required for this fault rectification process and the associated downtime of the lithography apparatus, the most efficient diagnostics on the lithography apparatus and / or the individual apparatus modules are essential. These include a module condition assessment in which a comparison against at least one constraint of a superordinate system is made. One of the constraints is, for example, that the module must report performance aberrations to a higher system instance of the lithography apparatus within a few milliseconds. However, these rapid reporting requirements are inconsistent with a module condition assessment that is expedient for the diagnosis, which is based on the most extensive condition assessment possible.

[0011] There are various methods for automatic fault diagnosis in different application areas. One method is to use sensors that continuously collect and analyse data in order to detect aberrations from normal operating conditions and issue corresponding alerts. Error codes play an important role in this process, as they permit errors to be identified and / or categorized. An error code is a unique identifier for a specific fault or a malfunction in a system or device, in this instance the lithography apparatus. When a fault occurs, a corresponding error code is generated, which often supplies the user or service personnel with rudimentary information about what fault has occurred and, if applicable, approaches to how the fault can be rectified. It may be that analysis of the error code is sufficient to repair the lithography apparatus without the need for additional manual inspection and / or analysis of the lithography apparatus.

[0012] Although error codes are a useful method for automatic fault diagnosis, there are some drawbacks to using error codes. One drawback is that error codes are often Carl Zeiss SMT GmbH

[0013] 3 very general and contain no detailed information about the cause of the fault and / or the necessary repair measures. This can result in service personnel having to spend time and resources for diagnosing and resolving the problem. Another drawback is that error codes are often not unique and may have multiple causes. In such cases, manual inspection and analysis is required in order to determine the exact reason for the fault.

[0014] Further, a time component, as already described at the outset, plays an important role in the evaluation of error codes, since it permits problems to be responded to quickly and, if necessary, system interventions to be carried out quickly. When a fault occurs, it is important for it to be quickly detected and rectified to minimize downtime and maintain system performance. In this context, error codes can help to respond to problems quickly as they permit the fault to be automatically identified and categorized. This can help to ensure that service personnel can quickly take suitable measures to rectify the fault and restore system performance.

[0015] Overall, the use of error codes may be a useful method for automatic fault diagnosis. However, due to the above, this method is not always sufficient to meet the need for rapid system interventions. For example, in general, error codes are not suitable for carrying out system interventions in the millisecond range because they are not specific enough to permit fast automated decisions in the lithography apparatus. This is because a wrong decision would lead to a technically unnecessary outage for the lithography apparatus, which must be avoided. Moreover, it is also possible for error codes to be triggered incorrectly and / or for multiple faults to occur simultaneously, making it difficult to diagnose and / or automatically respond to a particular fault and / or to weight faults among themselves in order to minimize dead time. Carl Zeiss SMT GmbH

[0016] 4

[0017] Against this background, a problem addressed by the present invention is that of providing an improved optical system and an improved method for condition monitoring.

[0018] According to a first aspect, an optical system of a lithography apparatus for, in particular cascaded, condition monitoring in the optical system and / or the lithography apparatus is proposed, comprising a first module having a first module control device, the first module being able to be monitored on the basis of at least one first system observable! a second module having a second module control device, the second module being able to be monitored on the basis of at least one second system observable! wherein the first module control device is configured to compare the at least first system observable with at least one first limit value criterion, and to generate a first error code for module condition monitoring on the basis of the comparison! and / or the second module control device is configured to compare the at least second system observable with at least one second limit value criterion, and to generate the first error code for module condition monitoring on the basis of the comparison! and a system control device configured to take the first error code as a basis for performing at least one control function for the optical system and / or the lithography apparatus, and to receive condition monitoring information of the first and / or the second module, and, based on the condition monitoring information of the first and / or the second module, to generate a second error code that provides, in particular detailed, system condition monitoring compared to the first error code.

[0019] The optical system comprises multiple modules, each module performing a specific function of the apparatus, for example, and being intended to be monitored. Each of the modules preferably has a module control device. A module control device can also be used for multiple modules. Each module is monitored on the basis of at least one "system observable". The observables are, for example, measured variables or conditions that are relevant to the functionality of the Carl Zeiss SMT GmbH

[0020] 5 apparatus. The module control devices compare the system observables with specific limit values to detect aberrations. For example, these limit values serve as a reference to establish whether the observed conditions are within acceptable parameters. Based on the comparisons between the system observables and the limit value criteria, first error codes are generated for each module in particular. These first error codes are preferably used to monitor the condition of the modules.

[0021] The central system control device performs control functions for the optical system and / or the lithography apparatus on the basis of the first error codes. This system control device preferably also receives condition monitoring information from the modules and generates the second error code therefrom on the basis of the condition information of the modules and / or the optical system and / or the lithography apparatus. The structure of the optical system permits cascaded monitoring, where the first error codes are generated and then a detailed second error code is generated. In principle, any number of additional error codes can also be generated in multiple cascades.

[0022] The proposed optical system meets a required design objective with regard to a mean time to diagnosis (MTTD), since the optical system can distinguish between different module -specific outages in particular reliably and quickly, preferably in the range from seconds to a few minutes. MTTD is a measure of how long it takes on average to detect and diagnose a fault or disruption in a system. In technical applications, such as lithography apparatuses, MTTD is a characteristic value for assessing the efficiency of fault rectification and the availability of the system. It is preferred for the MTTD to be as short as possible to minimize downtime and ensure rapid restoration of functionality. Depending on the complexity of the apparatus and the severity of the fault, the MTTD can range from seconds to a few minutes. The optical system thus provides a diagnostic tool and a diagnostic process that minimizes apparatus downtime (also known as "dead time") compared Carl Zeiss SMT GmbH

[0023] 6 to known diagnostic processes. Known diagnostic processes cause extended downtime for example due to incorrect or unreliable or misleading diagnostic actions.

[0024] The optical system preferably provides a fault reporting system that uses at least two different error codes. The first error code can also be referred to as the "fast / first" HLEC, and the second error code can be referred to as the "slow / sec- ond" HLEC. HLEC stands for "Health Level Error Code". This is an error code that indicates the state of health of a particular module of the lithography apparatus or of the lithography apparatus as a whole or of any other component. The fast HLEC preferably immediately, i.e. in the range from milliseconds to seconds, indicates a critical condition of a module or the lithography apparatus and thus permits rapid feedback to ensure a fast response and / or a remedy for the fault. The slow HLEC, on the other hand, preferably supplies more comprehensive information about the system condition of the modules of the lithography apparatus and / or of the lithography apparatus itself and preferably permits a detailed diagnosis for more in-depth analysis and fault resolution.

[0025] The, in particular automated, assessment of the system condition is preferably carried out by means of logical processing of the gathered condition information, in particular retrospectively in relation to the actual fault detection (by means of the first error code). This includes, by way of example, the logging and / or storage of retrospective condition information within at least one module and / or the lithography apparatus. The condition information particularly preferably permits the application of algorithms for detecting changes and / or the use of gradients for vital signs or health parameters. Vital signs are preferably observable variables that can be monitored to assess the state of health of the optical system. Moreover, the inclusion of error codes relating to the modules, which should also be understood as subsystems of the lithography apparatus, and preferably of system intervention detections increases the effectiveness of the fault assessment process. A system intervention detection is used to protect the optical system and is Carl Zeiss SMT GmbH

[0026] 7 preferably used to check and / or detect a critical system aberration that can lead to a potential outage and / or abnormal behaviour of the optical system. Detection of a critical system aberration can result in an intervention taking place, for example, which can result in particular in one or more modules and / or the optical system and / or the lithography apparatus being shut down. The presented modular design for fault reporting follows a fractal approach that relies on modularity and / or scalability. Each system level is preferably equipped in such a way that it can make use of the multi-error code approach. The multi-error code approach describes the generation of at least the first and the second error code as described in this instance. This promotes the modular concept. This, in turn, allows for various system configurations and system extensions. Further, the optical system presented in this instance permits the option of a system intervention on the basis of rapid feedback from the individual modules by means of the first error code, which facilitates a fast response to in particular critical faults. Moreover, error code-based separation of a "rapid" system intervention (for example a shutdown of the lithography apparatus or an apparatus part), which takes place on the basis of the first error code, from the detailed diagnostic task, which takes place on the basis of the second error code, ensures efficient resource allocation and clear demarcation of responsibilities in the fault analysis. The response to the first error code when a fault in a module is detected is preferably provided automatically by the lithography apparatus itself. A response to the second error code, on the other hand, may require human intervention in the fault resolution process.

[0027] It should be mentioned that the size and / or implementation of the modular design of the optical system and / or the lithography apparatus can be varied as desired. The design can range from a single module to a multiplicity and / or concatenation of any number of modules and / or submodules on any number of levels. This optical system is highly scalable and is encapsulated for fault assessment. Carl Zeiss SMT GmbH

[0028] 8

[0029] Ultimately, the modular design of the optical system also allows an implementation to be limited to possible submodules only and appropriately selected cascading to be used to nevertheless indicate a multiplicity or even all of the fault-influencing factors for the optical system or the lithography apparatus. This self-similar structure of the optical system makes it possible to save complexities in the overall system.

[0030] It should also be mentioned that the at least two error codes do not have to be implemented as software functions. Alternatively, the at least two error codes or at least one of the at least two error codes could also be sent from or to the modules and / or submodules as an arbitrarily coded signal on different lines, for example via a system fieldbus. It is also irrelevant to the function whether the at least two error codes are provided to the receiver in the same way or in different ways.

[0031] According to one embodiment, the first and / or the second system observable comprises information, in particular sensor signals and / or image information and / or module condition information, by means of which a module condition of the first and / or second module can be monitored and / or assessed.

[0032] The "system observables" are preferably parameters or measured variables that are used to monitor the modules. They can comprise various types of information, for example sensor signals, image information and module condition information. The system observables preferably supply information that permits the condition of a module to be monitored and assessed. This can be done by analysing sensor signals, images or other module condition information.

[0033] According to another embodiment, the control function provides a warning signal output and / or a shutdown of the optical system and / or the lithography apparatus. Carl Zeiss SMT GmbH

[0034] 9

[0035] The control function relates to a functionality of the optical system to which at least individual modules of the optical system, the optical system itself and / or the lithography apparatus, based on the information obtained, respond. The control function can include various actions aimed at responding to faults in the optical system and / or at least one of the modules. One of the possible actions that the control function can perform is output of warning signals. These warnings are used to inform users or operators of the optical system about potential faults or critical conditions. Another possible action of the control function is shutting down individual modules or module parts of the optical system and / or the optical system as a whole and / or the entire lithography apparatus. This may be necessary to prevent damage or to ensure safety when serious problems occur. This can, for example, prevent material overloading and / or material fatigue and / or increase machine safety and / or operator safety. The control function is activated to respond to critical conditions that may affect the functionality and / or safety of the optical system. By outputting warning signals or shutting down at least submodules of the optical system, the control function helps to minimize potential risks. Other control functions, for example a system restart, are also possible.

[0036] According to another embodiment, the condition monitoring information comprises the first and / or second system observable and / or information about a module history of the first and / or the second module, and / or about a history of the respective system observables and / or information about an analytically and / or stochastically determinable module dependency between at least the first and the second module. Module dependency in this instance is preferably also understood to mean an evaluation of measurement data collected or recorded module by module.

[0037] To generate the second error code, it is for example possible, based on the condition monitoring information, to access the history of a system observable, for example a sensor history of a module or system sensor, and to include in particular Carl Zeiss SMT GmbH

[0038] 10 retrospective data, such as a system observable history before the at least one limit value criterion was exceeded or underrun, in the system condition assessment. In addition, multiple system observables can be combined module by module and / or across modules in an analytical and / or logical (in particular on the basis of Boolean logic) and / or stochastic manner in order to identify complex causes of fault in this way. Different root causes can be taken into account, for example between the simultaneous occurrence of a fault in multiple modules and / or the occurrence of a fault in one module only. Moreover, certain criteria and / or system observables can be excluded or weighted among each other in order to permit a precise condition assessment. Further, the first error code and / or the already performed rapid system intervention and / or the potential presence or absence of faults in a submodule to one of the modules (keyword "fault cascading") is preferably also used for system assessment or for the condition assessment of the optical system and / or the lithography apparatus.

[0039] According to another embodiment, the system control device is configured to evaluate the condition monitoring information on the basis of at least one analytical and / or stochastic evaluation algorithm and / or on the basis of a, in particular selfteaching, machine learning model in order to generate the second error code and to provide the, in particular detailed, system condition monitoring and also a, in particular detailed, system condition assessment.

[0040] The system control device preferably describes a central unit in the optical system that is responsible for evaluating the condition monitoring information and generates the second error code on the basis thereof. This device coordinates the monitoring and assessment of the optical system. The condition monitoring information is preferably the data and / or information gathered from the modules and other parts of the optical system and / or the lithography apparatus and describing the condition of the optical system. The description of the system condition is preferably also referred to as a "condition monitoring". This information is used Carl Zeiss SMT GmbH

[0041] 11 by the system control device to analyse the condition of the system. The system control device uses at least one algorithm to analyse the condition monitoring information. This algorithm can be of an analytical nature, which means that it is based on mathematical models, or of a stochastic nature, which means that it is based on statistical methods.

[0042] The system control device can also use a machine learning model to analyse the condition monitoring information. In particular, such a machine learning model can be self-teaching, meaning that it teaches itself from the data provided by the optical system and adapts to changes in the optical system over time. The machine learning model can preferably be trained in the online training mode.

[0043] Based on the analysis of the condition monitoring information by means of the algorithms used and / or the machine learning model, the system control device generates a second error code. This second error code provides a detailed assessment of the system condition and permits specific problems or aberrations in the system to be identified. The second error code preferably not only supplies a statement about the condition of individual modules of the optical system and / or the optical system, but also makes detailed analysis and assessment of the entire lithography apparatus possible. This allows potential faults and / or malfunctions to be identified and, if necessary, fault rectification measures to be initiated.

[0044] According to another embodiment, the first error code comprises a module condition monitoring at module level, by means of which the first and / or the second module can be controlled, in particular module by module, on the basis of the control function.

[0045] The reduced complexity of the first error code permits the modules or system components involved to signal a specific fault situation with a fast response time, in particular in the millisecond range, and thus to respond quickly to the applicable fault or faults, for example by virtue of the optical system or at least Carl Zeiss SMT GmbH

[0046] 12 individual modules of the optical system and / or the lithography apparatus shutting themselves down, in particular for safety reasons. It should also be mentioned that the first error code can comprise one or more sub-error codes.

[0047] According to another embodiment, the second error code comprises a, in particular holistic, system condition monitoring and / or system condition assessment of the optical system and / or the lithography apparatus.

[0048] The detailed second error code permits the design knowledge about the optical system and / or the lithography apparatus to be used to perform a dedicated system condition assessment on the basis of system observables, such as sensors and / or condition information of the modules or of submodules. This allows the cause of fault or the search for a cause of fault to be narrowed down. Since the time-critical components of a fault response are already taken into account by means of the first error code, the system condition assessment may require more computing time for generating the second error code in order to thereby take into account all relevant aspects in sufficient depth in the troubleshooting. For preparing the second error code, in particular a deeper assessment, preferably by means of an assessment of the aforementioned historical time series data or sensor data, is made possible. It should also be mentioned that the second error code can comprise one or more sub-error codes.

[0049] The scope, quantity and / or speed, in particular the time in which the fault assessment is carried out, of the error codes can therefore vary without affecting the essential function of the optical system. Further, the testing depth of each of the individual error codes can also be adapted.

[0050] The second error code, like the first error code, may be written in a domain-specific language, this domain -specific programming language being tailored to system assessment requirements. The second error code permits a specialist for the Carl Zeiss SMT GmbH

[0051] 13 system assessment carried out on the basis of the second error code (e.g. service employee) not to have to provide any knowledge about software programming. Further, the developer programming the error code or the error code output does not need to be able to carry out a system assessment. This results in improved diagnostic capability following delivery. Diagnosis is also easier.

[0052] According to another embodiment, the first and / or second limit value criterion comprises a predetermined limit value and / or a predetermined limit interval and / or a predetermined limit value function.

[0053] The at least one limit value criterion is a criterion that is used to assess the system observable(s) in order to establish whether or not they are within acceptable parameters. A respective limit value criterion can apply to the first and / or the second module. The limit value criterion can also apply to multiple modules. The limit value criterion can comprise a predetermined limit value that serves as a reference point. This limit value is used to establish whether the observed conditions or measured variables are within acceptable limits. Alternatively or as a supplement, the limit value criterion can also contain a predetermined limit interval. Such an interval defines a range of acceptable values for the system observables. The limit value criterion can also include a predetermined limit value function. This function can be used to dynamically determine the limit values on the basis of various parameters or requirements.

[0054] According to another embodiment, the first and / or the second module comprises at least two submodules, preferably each having submodule control devices, the condition monitoring information of the respective submodule that is used for generating the second error code being able to be provided for submodule condition monitoring and / or a submodule error code, corresponding to the first error code, which can be generated on the basis of a respective comparison of at least Carl Zeiss SMT GmbH

[0055] 14 one submodule system observable with at least one submodule limit value criterion, being able to be provided.

[0056] The first and / or the second module may be divided into at least two submodules. These submodules can be smaller functional units within the module that perform specific tasks or functions. Each submodule or some submodules preferably have their own control device that is responsible for controlling and / or monitoring the respective submodule. These control devices permit independent control and / or monitoring of the submodules. Both the condition monitoring information and a submodule error code can be generated and provided to monitor the condition of the respective submodule. These submodule error codes are used to identify aberrations and / or faults in the operation of the submodules. The error codes are preferably generated on the basis of a comparison between the system observables of the submodules and the corresponding limit value criteria. This cascaded process preferably allows faults and / or aberrations in the performance and / or behaviour of the respective submodule to be identified.

[0057] It is not necessary for the individual submodules to provide their respective condition by way of two- or multi-level error code generation. Although this modular character of the optical system increases robustness, opportunities for use and accuracy for the fault detection, it is not required, but only optional. Some submodules may also comprise two- or multi-level error code generation, while other submodules provide only a first error code.

[0058] According to another embodiment, the detailed system condition monitoring can be taken as a basis for performing at least one, in particular module-specific, action, in particular a restart and / or system and / or module maintenance, relating to the optical system and / or the lithography apparatus. Preferably, the at least one action can be performed manually by an apparatus operator or semi-auto- matically or fully automatically. Carl Zeiss SMT GmbH

[0059] 15

[0060] The comprehensive monitoring of the system allows detailed information about the condition of the optical system and / or the lithography apparatus to be gathered. This information permits precise analysis of the performance and operating condition of the system. Based on the results of the system condition monitoring, specific actions can be performed that, for example, can relate (only) to specific modules or parts of the optical system. These actions are aimed at resolving problems or optimizing the performance of the system. One possible action is restarting at least one module of the optical system and / or the optical system and / or the lithography apparatus. This may be necessary to resolve software issues and / or restore the system after a disruption. Another action could be carrying out system and / or module maintenance to ensure the performance and reliability of the system. The at least one action can be performed in various ways. It can be initiated manually by an apparatus operator, who analyses the monitoring information and takes appropriate measures. Alternatively, it can be performed semi- automatically or fully automatically, the system independently taking the monitored condition information as a basis for deciding which actions are to be performed.

[0061] According to another embodiment, the first module and / or the second module each comprise a component of an optical system of a lithography apparatus, in particular a sensor, an actuator, an optical element, control electronics, an electronic device, a cooling device, a cooling circuit, and / or any other apparatus component.

[0062] According to another embodiment, each of the modules, be it the first or the second, comprises a specific component within the optical system of a lithography apparatus. These components can perform a multiplicity of functions within the optical system and / or the lithography apparatus and help to ensure the respective performance capability and / or functionality. Examples of components can be Carl Zeiss SMT GmbH

[0063] 16 sensors that are configured to collect and / or detect relevant measured variables and / or conditions. Actuators may be present to perform certain physical movements and / or actions within the optical system and / or the lithography apparatus. Moreover, the modules can also comprise control electronics or electronic devices that are responsible for controlling and / or monitoring various system components. Cooling devices or cooling circuits may be present to regulate the temperature of sensitive parts of the system and to ensure an optimum operating environment. Other apparatus components may be present depending on the specific requirements and configurations of the lithography apparatus and can include, for example, material feed systems, mechanical brackets and / or cleaning devices. Other components within the modules could include, for example, detectors, filters, fight sources, control interfaces, power supply units and / or data transmission devices. The exact composition of the components depends on the requirements of the lithography apparatus and the specific functions that each module is intended to perform.

[0064] Furthermore, a lithography apparatus having at least one optical system for condition monitoring as described above is proposed.

[0065] According to a second aspect, a computer-implemented method for, in particular cascaded, module condition monitoring in a lithography apparatus is proposed. The lithography apparatus comprises at least one optical system. The optical system comprises a first module that can be monitored on the basis of at least one first system observable, and a second module that can be monitored on the basis of at least one second system observable.

[0066] The computer-implemented method comprises the following steps. a) comparing the at least first system observable with at least one first limit value criterion, and generating a first error code for module condition monitoring on the basis of the comparison; and / or Carl Zeiss SMT GmbH

[0067] 17 b) comparing the at least second system observable with at least one second limit value criterion, and generating the first error code for module condition monitoring on the basis of the comparison! c) performing at least one control function for the optical system on the basis of the first error code! d) receiving condition monitoring information of the first and / or the second module! and e) based on the condition monitoring information of the first and / or the second module, generating a second error code that provides an in particular detailed system condition monitoring compared to the first error code.

[0068] The method in this instance is in particular two- or multi-level, since at least two error codes are generated successively in chronological order. This allows the different requirements placed on the error codes, namely firstly a fast response time and secondly detailed fault analysis, to be met simultaneously. The multi-level approach also permits design knowledge about the optical system to be integrated into the MMDC (Material Machine Damage Control). Further, the multilevel quality renders programming of logic operations in a low-level code of the control obsolete.

[0069] Implementing an effective fault reporting system requires a differentiated approach that meets the needs of a fast-moving technological environment. In this respect, two levels of error detection and assessment are introduced to permit comprehensive analysis and response to system anomalies.

[0070] On a first level, a response to at least one occurring fault is preferably provided on the basis of the first error code. This permits a system intervention in the millisecond range. This fast response is based on the initially generated, first error code, which can preferably be generated immediately after the evaluation of the at least one system observable, for example a module signal or system sensor Carl Zeiss SMT GmbH

[0071] 18 signal. This permits a direct intervention, for example in response to the exceeding of at least one limit value criterion by the respective module-specific (first and / or second or even further) system observable. On the first level, there is not yet a holistic system assessment, which is so desired in favour of a fast response time, however. On the first level, the respective system observable(s), in particular considered in isolation for each module, is / are merely compared against the respective module -specific or cross-module predefined limit value criterion module by module and at low computation power. This takes account of only a limited complexity of all the constraints of fault development compared to the level elucidated in greater detail below.

[0072] On a second level, an intensive, in particular detailed, system assessment or system analysis is carried out that in particular permits a comprehensive system diagnosis even taking into account complex dependencies between individual modules and / or groups of modules and / or module-specific or cross-module system observables. This detailed analysis results in generation of the second, detailed error code.

[0073] This two-level fault detection method and fault assessment method ensures an efficient and precise response to system anomalies, allowing the overall performance and reliability of the system to be improved.

[0074] Furthermore, a computer program product is proposed, which, on a program-con- trolled device, causes an apparatus of the method elucidated above to be operated.

[0075] A computer program product, e.g. a computer program means, can be provided or supplied for example on a storage medium, e.g. a memory card, a USB stick, a CD-ROM, a DVD, or in the form of a downloadable file from a server in a network. For example, in a wireless communications network, this can be effected by Carl Zeiss SMT GmbH

[0076] 19 transferring an appropriate file comprising the computer program product or the computer program means.

[0077] Furthermore, a computer-readable (storage) medium is proposed, comprising instructions that, when executed by a computer, cause said computer to carry out the method described above.

[0078] These instructions are preferably designed to cause a computer to carry out the method described earlier. In this case, a specific method or algorithm that is implemented in the computer is carried out or executed. By way of example, the medium may be a hard disk, a CD-ROM, a USB stick or another type of storage medium that stores the necessary instructions to cause the computer to carry out the method.

[0079] The optical system is preferably a projection optical unit of the lithography apparatus or projection exposure apparatus. However, the optical system may also be an illumination system. The lithography apparatus may be an EUV lithography apparatus. EUV stands for “extreme ultraviolet” and denotes a wavelength of the operating light of between 0.1 nm and 30 nm. The lithography apparatus may also be a DUV lithography apparatus. DUV stands for "deep ultraviolet" and denotes a wavelength of the operating light of between 30 nm and 250 nm.

[0080] "A" or "an" in this instance should not necessarily be regarded as a restriction to exactly one element. Instead, there may also be provision for multiple elements, for example two, three or more. Any other numeral used here should also not be understood as a restriction to exactly the stated number of elements. Rather, unless indicated otherwise, numerical variances upwards and downwards are possible. Carl Zeiss SMT GmbH

[0081] 20

[0082] The embodiments and features described for the optical system apply to the lithography apparatus and the proposed method in corresponding fashion, and vice versa.

[0083] Further possible implementations of the invention also comprise non -explicitly mentioned combinations of features or embodiments described hereinabove or hereinafter with regard to the exemplary embodiments. A person skilled in the art will also add individual aspects as improvements or supplementations to the respective basic form of the invention.

[0084] Further advantageous configurations and aspects of the invention are the subject of the dependent claims and of the exemplary embodiments of the invention that are described hereinafter. The invention is elucidated in greater detail hereinafter on the basis of preferred embodiments with reference to the appended figures.

[0085] Fig. 1 shows a schematic meridional section through a lithography apparatus for EUV projection lithography;

[0086] Fig. 2 shows a schematic block diagram of a lithography apparatus having one exemplary embodiment of an optical system;

[0087] Fig. 3 shows a schematic block diagram of a lithography apparatus having another exemplary embodiment of an optical system; and

[0088] Fig. 4 shows a schematic flow diagram of an exemplary embodiment of a method for module condition monitoring in a lithography apparatus.

[0089] In the figures, identical or functionally identical elements have been provided with the same reference signs, unless indicated otherwise. Further, it should be noted that the representations in the figures are not necessarily true to scale. Carl Zeiss SMT GmbH

[0090] 21

[0091] Fig. 1 shows an embodiment of a lithography apparatus 1 (projection exposure apparatus), in particular an EUV lithography apparatus. One embodiment of an illumination system 2 of the lithography apparatus 1 has, in addition to a light or radiation source 3, an illumination optical unit 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 may also be provided as a module separate from the rest of the illumination system 2. In this case, the illumination system 2 does not comprise the light source 3.

[0092] A reticle 7 arranged in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 is displaceable by way of a reticle displacement drive 9, in particular in a scanning direction.

[0093] Fig. 1 depicts, by way of elucidation, a Cartesian coordinate system with an x-di- rection x, a ydirection y and a z-direction z. The x-direction x runs perpendicularly into the plane of the drawing. The ydirection y runs horizontally, and the z- direction z runs vertically. The scanning direction runs in the ydirection y in Fig. 1. The z-direction z runs perpendicularly to the object plane 6.

[0094] The lithography apparatus 1 comprises a projection optical unit 10. The projection optical unit 10 is used to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 runs parallel to the object plane 6. Alternatively, an angle between the object plane 6 and the image plane 12 that differs from 0° is also possible.

[0095] A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable by way of a wafer displacement drive 15, in particular in the ydirection y. The displacement, firstly, of the reticle 7 by way of the reticle displacement drive 9 and, secondly, of Carl Zeiss SMT GmbH

[0096] 22 the wafer 13 by way of the wafer displacement drive 15 can be implemented so as to be in sync with one another.

[0097] The light source 3 is an EUV radiation source. The light source 3 emits in particular EUV radiation 16, which is also referred to below as used radiation, illumination radiation or illumination light. The used radiation 16 has in particular a wavelength in the range between 5 nm and 30 nm. The light source 3 may be a plasma source, for example an LPP ( Laser Produced Plasma) source or a DPP ( Gas-Discharge Produced Plasma) source. It may also be a synchrotron-based radiation source. The light source 3 may be a free-electron laser ( FEL).

[0098] The illumination radiation 16 emanating from the light source 3 is focused by a collector 17. The collector 17 may be a collector having one or more ellipsoidal and / or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 17 can be impinged upon by the illumination radiation 16 with grazing incidence ( Gl), that is to say with angles of incidence greater than 45°, or with normal incidence ( Nl), that is to say with angles of incidence less than 45°. The collector 17 may be structured and / or coated firstly to optimize its reflectivity for the used radiation and secondly to suppress extraneous light.

[0099] Downstream of the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the light source 3 and the collector 17, and the illumination optical unit 4.

[0100] The illumination optical unit 4 comprises a deflection mirror 19 and, arranged downstream thereof in the beam path, a first facet mirror 20. The deflection mirror 19 may be a planar deflection mirror or, alternatively, a mirror with a beaminfluencing effect that goes beyond the pure deflection effect. As an alternative or in addition, the deflection mirror 19 may take the form of a spectral filter that Carl Zeiss SMT GmbH

[0101] 23 separates a used light wavelength of the illumination radiation 16 from extraneous light of a wavelength differing therefrom. If the first facet mirror 20 is arranged in a plane of the illumination optical unit 4 which is optically conjugated to the object plane 6 as a field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a multiplicity of individual first facets 21, which can also be referred to as field facets. Only some of these first facets 21 are shown in Fig. 1 by way of example.

[0102] The first facets 21 may take the form of macroscopic facets, in particular the form of rectangular facets or the form of facets with an arcuate or partly circular peripheral contour. The first facets 21 may take the form of planar facets or, alternatively, convexly or concavely curved facets.

[0103] As is known from DE 10 2008 009 600 Al, for example, the first facets 21 themselves may each also be composed of a multiplicity of individual mirrors, in particular a multiplicity of micromirrors. The first facet mirror 20 may be in the form of a microelectromechanical system (MEMS system) in particular. For details, reference is made to DE 10 2008 009 600 Al.

[0104] The illumination radiation 16 travels horizontally, i.e. in the ydirection y, between the collector 17 and the deflection mirror 19.

[0105] In the beam path of the illumination optical unit 4, a second facet mirror 22 is disposed downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in a pupil plane of the illumination optical unit 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 may also be arranged at a distance from a pupil plane of the illumination optical unit 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 Al, EP 1 614 008 Bl and US 6,573,978. Carl Zeiss SMT GmbH

[0106] 24

[0107] The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

[0108] The second facets 23 may also be macroscopic facets, which may for example have a round, rectangular or hexagonal boundary, or may alternatively be facets composed of micromirrors. In this regard, reference is also made to DE 10 2008 009 600 Al.

[0109] The second facets 23 may have planar or, alternatively, convexly or concavely curved reflection surfaces.

[0110] The illumination optical unit 4 thus forms a doubly faceted system. This fundamental principle is also referred to as a honeycomb condenser (or fly’s eye integrator).

[0111] It may be advantageous to arrange the second facet mirror 22 not exactly in a plane that is optically conjugated to a pupil plane of the projection optical unit 10. In particular, the second facet mirror 22 may be arranged so as to be tilted in relation to a pupil plane of the projection optical unit 10, as described for example in DE 10 2017 220 586 Al.

[0112] The second facet mirror 22 is used to image the individual first facets 21 into the object field 5. The second facet mirror 22 is the last beam-shaping mirror or actually the last mirror for the illumination radiation 16 in the beam path upstream of the object field 5.

[0113] In another embodiment (not shown) of the illumination optical unit 4, a transfer optical unit contributing in particular to the imaging of the first facets 21 into the object field 5 may be arranged in the beam path between the second facet mirror Carl Zeiss SMT GmbH

[0114] 25

[0115] 22 and the object field 5. The transfer optical unit can comprise exactly one mirror, or alternatively two or more mirrors, which are arranged one behind the other in the beam path of the illumination optical unit 4. The transfer optical unit can in particular comprise one or two normal-incidence mirrors (NI mirrors) and / or one or two grazing-incidence mirrors (GI mirrors).

[0116] In the embodiment shown in Fig. 1, the illumination optical unit 4 has exactly three mirrors downstream of the collector 17, specifically the deflection mirror 19, the first facet mirror 20 and the second facet mirror 22.

[0117] In another embodiment of the illumination optical unit 4, the deflection mirror 19 may also be omitted, and so the illumination optical unit 4 can then have exactly two mirrors downstream of the collector 17, specifically the first facet mirror 20 and the second facet mirror 22.

[0118] The imaging of the first facets 21 into the object plane 6 by means of the second facets 23 or using the second facets 23 and a transfer optical unit is often only approximate imaging.

[0119] The projection optical unit 10 comprises a plurality of mirrors Mi, which are consecutively numbered in accordance with their arrangement in the beam path of the lithography apparatus 1.

[0120] In the example shown in Fig. 1, the projection optical unit 10 comprises six mirrors Ml to M6. Alternatives with four, eight, ten, twelve or any other number of mirrors Mi are also possible. The projection optical unit 10 is a doubly obscured optical unit. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optical unit 10 has an image-side numerical aperture that is greater than 0.5 and may also be greater than 0.6 and for example may be 0.7 or 0.75. Carl Zeiss SMT GmbH

[0121] 26

[0122] Reflection surfaces of the mirrors Mi may take the form of free-form surfaces without an axis of rotational symmetry. Alternatively, the reflection surfaces of the mirrors Mi may be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflection surface shape. Just like the mirrors of the illumination optical unit 4, the mirrors Mi may have highly reflective coatings for the illumination radiation 16. These coatings may be designed as multi-layer coatings, in particular with alternating layers of molybdenum and silicon.

[0123] The projection optical unit 10 has a large object image shift in the ydirection y between a ycoordinate of a centre of the object field 5 and a ycoordinate of the centre of the image field 11. This object image shift in the ydirection y may be of approximately the same magnitude as a z-distance between the object plane 6 and the image plane 12.

[0124] The projection optical unit 10 may in particular have an anamorphic form. In particular, it has different imaging scales Bx, By in the x- and y- directions x, y. The two imaging scales Bx, By of the projection optical unit 10 are preferably (Bx, By) = (+ / -0.25, + / -0.125). A positive imaging scale B means imaging without image inversion. A negative sign for the imaging scale B means imaging with image inversion.

[0125] The projection optical unit 10 consequently leads to a reduction in size with a ratio of 4'1 in the x-direction x, i.e. in a direction perpendicular to the scanning direction.

[0126] The projection optical unit 10 leads to a reduction in size of 8H in the ydirection y, i.e. in the scanning direction. Carl Zeiss SMT GmbH

[0127] 27

[0128] Other imaging scales are also possible. Imaging scales with the same sign and the same absolute value in the x- direction x and y- direction y are also possible, for example with absolute values of 0.125 or of 0.25.

[0129] The number of intermediate image planes in the x- direction x and in the y- direction y in the beam path between the object field 5 and the image field 11 may be the same or may differ, depending on the embodiment of the projection optical unit 10. Examples of projection optical units with different numbers of such intermediate images in the x-direction x and the ydirection y are known from US 2018 / 0074303 Al.

[0130] In each case one of the second facets 23 is assigned to exactly one of the first facets 21 in order to form a respective illumination channel for illuminating the object field 5. This may in particular produce illumination according to the Kohler principle. The far field is decomposed into a multiplicity of object fields 5 using the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 respectively assigned to them.

[0131] By way of an assigned second facet 23, the first facets 21 are each imaged onto the reticle 7 and overlaid on one another for the purpose of illuminating the object field 5. The illumination of the object field 5 is in particular of maximum homogeneity. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by overlaying different illumination channels.

[0132] An arrangement of the second facets 23 can be used to geometrically define the illumination of the entrance pupil of the projection optical unit 10. The intensity distribution in the entrance pupil of the projection optical unit 10 can be set by selecting the illumination channels, in particular the subset of the second facets 23 that guide light. This intensity distribution is also referred to as an illumination setting or illumination pupil filling. Carl Zeiss SMT GmbH

[0133] 28

[0134] A likewise preferred pupil uniformity in the region of portions of an illumination pupil of the illumination optical unit 4 which are illuminated in a defined manner can be achieved by redistributing the illumination channels.

[0135] Further aspects and details of the illumination of the object field 5 and, in particular, of the entrance pupil of the projection optical unit 10 are described below.

[0136] The projection optical unit 10 may have in particular a homocentric entrance pupil. The latter may be accessible. It may also be inaccessible.

[0137] The entrance pupil of the projection optical unit 10 regularly cannot be exactly illuminated using the second facet mirror 22. In the case of imaging by the projection optical unit 10 which telecentrically images the centre of the second facet mirror 22 onto the wafer 13, the aperture rays often do not intersect at a single point. However, it is possible to find an area in which the spacing of the aperture rays that is determined in pairs becomes minimal. This area is the entrance pupil or an area conjugated thereto in real space. In particular, this area exhibits a finite curvature.

[0138] It may be the case that the projection optical unit 10 has different positions of the entrance pupil for the tangential beam path and for the sagittal beam path. In this case, an imaging element, in particular an optical structural element of the transfer optical unit, should be provided between the second facet mirror 22 and the reticle 7. This optical element can be used to take into account the different position of the tangential entrance pupil and the sagittal entrance pupil.

[0139] In the arrangement of the components of the illumination optical unit 4 shown in Fig. 1, the second facet mirror 22 is arranged in an area conjugated to the entrance pupil of the projection optical unit 10. The first facet mirror 20 is arranged Carl Zeiss SMT GmbH

[0140] 29 so as to be tilted with respect to the object plane 6. The first facet mirror 20 is arranged so as to be tilted with respect to an arrangement plane defined by the deflection mirror 19. The first facet mirror 20 is arranged so as to be tilted with respect to an arrangement plane defined by the second facet mirror 22.

[0141] Fig. 2 shows a schematic block diagram of the lithography apparatus 1 having an optical system 200. The optical system 200 is configured for (system or module) condition monitoring in the optical system 200 itself and / or the lithography apparatus 1.

[0142] The optical system 200 comprises a first module 202 having a first module control device 204. The first module 202 can be monitored on the basis of at least one first system observable.

[0143] Further, the optical system 200 comprises a second module 206 having a second module control device 208. The second module 206 can be monitored on the basis of at least one second system observable.

[0144] The optical system 200 may also have more than two modules 202, 206, in particular N modules. An n-th module 210 having an N-th module control device 212 is also shown schematically in Fig. 2. The n-th module 210 can be monitored by means of at least one n-th system observable.

[0145] The first and / or the second and / or the up-to-n-th system observable comprises, for example, information in the form of sensor signals and / or image information and / or module condition information, by means of which a respective module condition of the first and / or second and / or up-to-n-th module 202, 206, 210 can be monitored and / or assessed. Carl Zeiss SMT GmbH

[0146] 30

[0147] The first module control device 204 is configured to compare the at least first system observable with at least one first limit value criterion, and to generate a first error code 214 for module condition monitoring on the basis of the comparison.

[0148] Alternatively or as a supplement thereto, the second module control device 208 is configured to compare the at least second system observable with at least one second limit value criterion, and to generate the first error code 214 for module condition monitoring on the basis of the comparison.

[0149] Alternatively or as a supplement thereto, the up-to-n-th module control device 212 is configured to compare the up to at least n-th system observable with at least one up-to-n-th limit value criterion, and to generate the first error code 214 for module condition monitoring on the basis of the comparison.

[0150] The first and / or second and / or up-to-n-th limit value criterion may have a predetermined limit value and / or a predetermined limit interval and / or a predetermined limit value function. Further, such a limit value criterion can also be determined for multiple modules across modules or in each case for a specific group of modules.

[0151] Further, the optical system 200 comprises a system control device 216. The system control device 216 is configured to perform at least one control function for the optical system 200 on the basis of the first error code 214. The control function can provide, for example, a warning signal output and / or a shutdown of the optical system 200 and / or the lithography apparatus 1. Other control functions are also possible.

[0152] The first error code 214 is also referred to as the "fast / first" HLEC, HLEC standing for "Health Level Error Code". The first error code can be generated per module, i.e. at module level. The first error code 214 thus comprises a module Carl Zeiss SMT GmbH

[0153] 31 condition monitoring at module level, by means of which the first and / or the second and / or the up-to-n-th module 202, 206, 210 can be controlled, in particular module by module, on the basis of the control function.

[0154] The system control device 216 is also configured to receive respective (module) condition monitoring information 218 from in each case the first module 202 and / or the second module 206 and / or the up-to-n-th module 210. The condition monitoring information 218 may, for example, comprise the first and / or second system observable and / or information about the first error code and / or information about the respective module-bymodule comparison and / or information about a module history of the first module 202 and / or the second module 206 and / or the up-to-n-th module 210, and / or information about a history of the respective system observables and / or information about an analytically and / or stochastically determinable module dependency between at least the first module 202 and / or the second module 206 and / or the up-to-n-th module 210. The condition monitoring information 218 is preferably provided by each module 202, 206, 210 of the system control device 216 for evaluation.

[0155] The system control device 216 is also configured to generate, based on the provided condition monitoring information 218 of the first module 202 and / or the second module 206 and / or the up-to-n-th module 210, which is in particular provided module by module, a second error code 220 that provides a detailed system condition monitoring compared to the first error code 214. The second error code 220 can also be referred to as the "slow / second" HLEC. The condition monitoring information 218 can also be referred to as HLEC condition monitoring information. The second error code 220 comprises a system condition monitoring and / or system condition assessment of the optical system 200 and / or the lithography apparatus 1. Carl Zeiss SMT GmbH

[0156] 32

[0157] The system control device 216 is configured to evaluate the condition monitoring information 218 on the basis of at least one analytical and / or stochastic evaluation algorithm and / or on the basis of a, in particular self-teaching, machine learning model in order to generate the second error code 220 and to provide the system condition monitoring and also a system condition assessment of the optical system 200 and / or the lithography apparatus 1. This detailed system condition monitoring can then be taken as a basis for performing at least one action, in particular a restart and / or system and / or module maintenance, relating to the optical system 200 and / or the lithography apparatus 1.

[0158] Fig. 3 shows a schematic block diagram of the lithography apparatus 1 having an optical system 300. The explanations provided above for the optical system 200 apply to the optical system 300 in corresponding fashion, and vice versa. Accordingly, to avoid repetition, only features of the embodiment of the optical system 300 are described that are not shown in Fig. 2. It goes without saying that at least some of the features in other embodiments may also be present in the optical system 200. Therefore, the reference signs from Fig. 2 are also used for the overlapping features in Fig. 3.

[0159] According to Fig. 3, the first module 202, the second module 206 and the up-to-n- th module 210 each comprise at least two submodules 302, 304. The respective submodule 302 preferably comprises a submodule control device 306. The respective submodule 304 preferably comprises a submodule control device 308. A cross-submodule submodule control device can also be used for multiple submodules (not shown).

[0160] In the embodiment shown, at least the condition monitoring information 218 used for generating the second error code 220 is provided to the respective module control device 204, 208, 212. In other embodiments, a submodule error code can also be provided, which can be generated on the basis of a respective Carl Zeiss SMT GmbH

[0161] 33 comparison of at least one submodule system observable with at least one submodule limit value criterion. The respective submodule error code can be provided, for example, to the respective hierarchically superordinate module control device 204, 208, 212, and can be provided from each of the latter to the system control device 216.

[0162] The system control device 216 thus preferably receives not only, from each module 202, 206, 210, the first error code 214 and / or the condition monitoring information 218 used for generating the second error code 220, but, as a supplement thereto, preferably also the condition monitoring information 218 of the respective submodules 302, 304 and / or the respective submodule error codes thereof. This allows error analysis as far as a submodule level. It goes without saying that each submodule 302, 304 may be divided into further sub-submodules multiple times.

[0163] The first module 202 and / or the second module 206 and / or the up-to-n-th module 210 may each have a component of an optical system 200, 300 of the lithography apparatus 1. This may be, purely by way of example, a sensor, an actuator, an optical element, control electronics, an electronic device, a cooling device, a cooling circuit, and / or any other apparatus component of the lithography apparatus 1.

[0164] Fig. 4 shows a schematic flow diagram of a method for module condition monitoring in the lithography apparatus 1. The lithography apparatus 1 comprises, as in the aforementioned examples, the at least one optical system 200, 300. The at least one optical system 200, 300 comprises at least the first module 202, which can be monitored on the basis of at least one first system observable, at least the second module 206, which can be monitored on the basis of at least one second system observable, and preferably at least the up-to-n-th module 210, which can be monitored on the basis of at least one up-to-n-th system observable. Carl Zeiss SMT GmbH

[0165] 34

[0166] The method is preferably computer-implemented, i.e. can be carried out by means of a computer or computer means.

[0167] In a step Si A, the method comprises comparing the at least first system observable with at least one first limit value criterion, and generating S2A a first error code for module condition monitoring on the basis of the comparison.

[0168] Alternatively or as a supplement, the method comprises, in a step SIB, comparing the at least second system observable with at least one second limit value criterion, and generating S2B the first error code for module condition monitoring on the basis of the comparison.

[0169] Furthermore, alternatively or as a supplement, but not shown in Fig. 4, the method can comprise, in an optional, additional step, comparing the up-to-n-th system observable with at least one up-to-n-th limit value criterion, and optionally generating the first error code for module condition monitoring on the basis of the comparison.

[0170] In a step S3, the method comprises performing at least one control function for the optical system on the basis of the first error code.

[0171] In a step S4, the method comprises receiving condition monitoring information of the first and / or the second module and / or the up-to-n-th module.

[0172] In a step S5, the method comprises generating a second, in particular detailed, error code that provides a detailed or comprehensive system monitoring or system assessment compared to the first error code. The second error code is generated on the basis of the condition monitoring information of the first and / or the second module and / or the up-to-n-th module. Carl Zeiss SMT GmbH

[0173] 35

[0174] The method can be carried out as a computer program product on a program-con- trolled device 400. The computer program product can thus cause the lithography apparatus 1 to be operated. Further, a computer-readable (storage) medium 402 may be provided, comprising instructions that, when executed by a computer (not shown), cause said computer to carry out the method described in the present instance.

[0175] By way of example, the optical system 200, 300 can also be used in a DUV lithog- raphy apparatus.

[0176] Although the present invention has been described with reference to exemplary embodiments, it is modifiable in a variety of ways.

[0177] Carl Zeiss SMT GmbH

[0178] 36

[0179] LIST OF REFERENCE SIGNS

[0180] 1 Lithography apparatus

[0181] 2 Illumination system

[0182] 3 Light source

[0183] 4 Illumination optical unit

[0184] 5 Object field

[0185] 6 Object plane

[0186] 7 Reticle

[0187] 8 Reticle holder

[0188] 9 Reticle displacement drive

[0189] 10 Projection optical unit

[0190] 11 Image field

[0191] 12 Image plane

[0192] 13 Wafer

[0193] 14 Wafer holder

[0194] 15 Wafer displacement drive

[0195] 16 Illumination radiation

[0196] 17 Collector

[0197] 18 Intermediate focal plane

[0198] 19 Deflection mirror

[0199] 20 First facet mirror

[0200] 21 First facet

[0201] 22 Second facet mirror

[0202] 23 Second facet

[0203] 200 Optical system

[0204] 202 Module

[0205] 204 Module control device

[0206] 206 Module

[0207] 208 Module control device Carl Zeiss SMT GmbH

[0208] 37

[0209] 210 Module

[0210] 212 Module control device

[0211] 214 First error code

[0212] 216 System control device

[0213] 218 Condition monitoring information

[0214] 220 Second error code

[0215] 300 Optical system

[0216] 302 Submodule

[0217] 304 Submodule

[0218] 306 Submodule control device

[0219] 308 Submodule control device

[0220] 400 Program-controlled device

[0221] 402 Computer-readable (storage) medium

[0222] Ml Mirror

[0223] M2 Mirror

[0224] M3 Mirror

[0225] M4 Mirror

[0226] M5 Mirror

[0227] M6 Mirror

Claims

Carl Zeiss SMT GmbH38 PATENT CLAIMS1. Optical system (200, 300) of a lithography apparatus (1) for condition monitoring in the optical system (200, 300), comprising a first module (202, 210) having a first module control device (204), the first module (202, 210) being able to be monitored on the basis of at least one first system observable; a second module (206, 210) having a second module control device (208), the second module (206, 210) being able to be monitored on the basis of at least one second system observable; wherein the first module control device (204, 212) is configured to compare the at least first system observable with at least one first limit value criterion, and to generate a first error code (214) for module condition monitoring on the basis of the comparison; and / or the second module control device (208, 212) is configured to compare the at least second system observable with at least one second limit value criterion, and to generate the first error code (214) for module condition monitoring on the basis of the comparison; and a system control device (216) configured to take the first error code (214) as a basis for performing at least one control function for the optical system (200, 300) and / or the lithography apparatus (1), and to receive condition monitoring information (218) of the first and / or the second module (202, 206, 210), and, based on the condition monitoring information (218) of the first and / or the second module (202, 206, 210), to generate a second error code (220) that provides a system condition monitoring compared to the first error code (214).

2. Optical system according to Claim 1, wherein the first and / or the second system observable comprises information, in particular sensor signals and / or image information and / or module conditionCarl Zeiss SMT GmbH39 information, by means of which a module condition of the first and / or second module (202, 206, 210) can be monitored and / or assessed.

3. Optical system according to Claim 1 or 2, wherein the control function provides a warning signal output and / or a shutdown of the optical system (200, 300) and / or the lithography apparatus (1).

4. Optical system according to one of Claims 1 to 3, wherein the condition monitoring information (218) comprises the first and / or second system observable and / or information about a module history of the first and / or the second module (202, 206, 210), and / or about a history of the respective system observables and / or information about an analytically and / or stochastically determinable module dependency between at least the first and the second module (202, 206, 210).

5. Optical system according to one of Claims 1 to 4, wherein the system control device (216) is configured to evaluate the condition monitoring information (218) on the basis of at least one analytical and / or stochastic evaluation algorithm and / or on the basis of a, in particular self-teaching, machine learning model in order to generate the second error code and to provide the system condition monitoring and also a system condition assessment.

6. Optical system according to one of Claims 1 to 5, wherein the first error code (214) comprises a module condition monitoring at module level, by means of which the first and / or the second module (202, 206, 210) can be controlled, in particular module by module, on the basis of the control function.

7. Optical system according to one of Claims 1 to 6,Carl Zeiss SMT GmbH40 wherein the second error code (220) comprises a system condition monitoring and / or system condition assessment of the optical system (200, 300) and / or the lithography apparatus (1).

8. Optical system according to one of Claims 1 to 7, wherein the first and / or second limit value criterion comprises a predetermined limit value and / or a predetermined limit interval and / or a predetermined limit value function.

9. Optical system according to one of Claims 1 to 8, wherein the first and / or the second module (202, 206, 210) comprises at least two submodules (302, 304), preferably each having submodule control devices (306, 308), the condition monitoring information (218) of the respective submodule (302, 304) that is used for generating the second error code (220) being able to be provided for submodule condition monitoring, and / or a submodule error code, corresponding to the first error code (314), which can be generated on the basis of a respective comparison of at least one submodule system observable with at least one submodule limit value criterion, being able to be provided.

10. Optical system according to one of Claims 1 to 9, wherein the system condition monitoring can be taken as a basis for performing at least one action, in particular a restart and / or system and / or module maintenance, relating to the optical system (200, 300) and / or the lithography apparatus (1).

11. Optical system according to one of Claims 1 to 10, wherein the first module (202, 210) and / or the second module (206, 210) each comprise a component of an optical system (200, 300) of a lithography apparatus (1), in particular a sensor, an actuator, an optical element, control electronics, anCarl Zeiss SMT GmbH41 electronic device, a cooling device, a cooling circuit, and / or any other apparatus component.

12. Lithography apparatus (1) having an optical system (200, 300) according to one of Claims 1 to 11.

13. Computer-implemented method for module condition monitoring in a lithography apparatus (1) having an optical system (200, 300), comprising a first module (202, 210) that can be monitored on the basis of at least one first system observable, and a second module (206, 210) that can be monitored on the basis of at least one second system observable, the computer-implemented method comprising a) comparing (S1A) the at least first system observable with at least one first limit value criterion, and generating (SIB) a first error code (214) for module condition monitoring on the basis of the comparison! and / or b) comparing (S2A) the at least second system observable with at least one second limit value criterion, and generating (S2B) the first error code (214) for module condition monitoring on the basis of the comparison! c) performing (S3) at least one control function for the optical system (200, 300) on the basis of the first error code (214); d) receiving (S4) condition monitoring information (218) of the first and / or the second module (202, 206, 210); and e) based on the condition monitoring information (218) of the first and / or the second module (202, 206, 210), generating (S5) a second error code (220) that provides a system condition monitoring compared to the first error code (214).

14. Computer program product, which, on a program-controlled device (400), causes the method according to Claim 13 to be carried out.Carl Zeiss SMT GmbH4215. Computer-readable (storage) medium (402), comprising instructions that, when executed by a computer, cause said computer to carry out the method according to Claim 13.

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