Methods, apparatuses, and media for aberration analysis of an extreme ultraviolet lithography system

Abstract

The disclosure provides a method for aberration analysis of an extreme ultraviolet lithography system, comprising constructing a spatial energy distribution model of a shared hot zone, reconstructing a composite aberration original field caused by overlapping thermal creep of adjacent mirrors in the shared hot zone, extracting a main trend field composed of common thermal deformation of adjacent mirrors, separating a residual field representing independent deformation contribution of the mirrors from the composite aberration original field, distributing deformation in the residual field to corresponding responsible mirrors to form single-mirror attributable aberration fields, assigning weights to each single-mirror attributable aberration field based on the degree of influence of the single-mirror attributable aberration field on imaging quality, synthesizing the weighted single-mirror aberration fields and the main trend field to generate a final aberration analysis result for aberration compensation, which can effectively identify, separate and attribute the composite aberration caused by overlapping thermal creep of adjacent mirrors, and ensure long-term imaging stability and reliability of the extreme ultraviolet lithography system under efficient operation.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing equipment technology, and in particular to a method, apparatus and medium for aberration analysis of an extreme ultraviolet lithography system. Background Technology

[0002] Extreme ultraviolet (EUV) lithography uses extremely short-wavelength UV light and employs a multi-mirror chain consisting of a series of high-precision mirrors to guide and focus the light. To maintain sufficient light intensity, these mirrors need to be continuously exposed to high-energy-density UV beams. During the long-duration, high-frequency continuous exposure process of the lithography machine, each mirror experiences a temperature rise due to absorbing light energy, and after several hours of thermal shock, undergoes slow and minute permanent deformation, known as thermal creep. Traditional aberration analysis methods are based on the assumption that the thermal creep of each mirror is independent. They decompose system aberrations into components such as basis aberration, field curvature, and astigmatism, attributing them to specific mirrors, thereby guiding mirror topography correction to maintain image quality.

[0003] However, under constant exposure cycle, scanning speed, and illumination conditions, adjacent mirrors may simultaneously cause significant temperature rises in the same area of ​​the beam. Due to differences in mirror materials and structures, their thermal creep varies in amplitude and direction, leading to spatial superposition of deformations and forming a complex aberration structure that cannot be attributed to any single mirror. This complex structure manifests as inseparable cross terms in the aberration decomposition matrix, violating the additivity basis of traditional aberration attribution models. This makes it impossible for the system to accurately trace the aberration to the specific responsible mirror after detection, causing subsequent aberration compensation and mirror reshaping to lose their precise target. Image quality deteriorates continuously after long-term operation, directly impacting chip manufacturing yield.

[0004] Therefore, there is an urgent need for an analytical method that can effectively identify, separate, and attribute the complex aberrations caused by thermal creep of overlapping adjacent mirrors, in order to break through the bottleneck of existing aberration compensation technology and ensure the long-term imaging stability and reliability of the extreme ultraviolet lithography system under high-efficiency operation. Summary of the Invention

[0005] In view of this, in order to solve the problems caused by the prior art, this application provides a method for aberration analysis of extreme ultraviolet lithography system.

[0006] In a first aspect, this disclosure provides a method comprising:

[0007] S1, Construct a spatial energy distribution model of the shared hot zone formed by the synchronous heating of adjacent mirror surfaces under continuous exposure conditions;

[0008] S2, Based on the spatial energy distribution model, reconstruct the original field of composite aberrations caused by the thermal creep of overlapping adjacent mirrors within the shared thermal zone;

[0009] S3, extract the main trend field composed of the common thermal deformation of adjacent mirrors from the original composite aberration field, and subtract the main trend field from the original composite aberration field to separate the residual field characterizing the independent deformation contribution of the mirrors;

[0010] S4. Based on the optical path geometry and the order of light reflection, the deformation in the residual field is distributed to the corresponding responsible mirror to form a single-mirror attributable aberration field.

[0011] S5, assign weights to each of the single-mirror attributable aberration fields based on their impact on image quality, and synthesize the weighted aberration fields of each mirror with the main trend field to generate the final aberration analysis result for aberration compensation.

[0012] Optionally, S1 includes:

[0013] Exposure parameters and spatial energy data are collected to generate an energy deposition sequence, and this sequence is mapped and accumulated to each mirror according to the physical order of the optical path to generate an energy accumulation matrix for each mirror.

[0014] By comparing the energy accumulation matrices of adjacent mirrors, a common high-energy region map between mirrors can be identified and generated.

[0015] Energy filtering and spatial merging are performed on the common high-energy region map to generate a shared thermal zone spatial map with clear physical boundaries.

[0016] Optionally, the generation of the energy deposition sequence includes: determining the effective exposure duration based on the exposure cycle, scan speed, and illuminance distribution map, and calculating the transient energy deposition density at time t and spatial coordinates (x, y). .

[0017] Optionally, S2 includes:

[0018] Based on the shared thermal zone spatial map, the shared thermal zone interference sequence is extracted from the full-field interferogram;

[0019] The shared hot zone interference sequence is sequentially subjected to phase demodulation and phase expansion to obtain the expanded phase field within the shared hot zone;

[0020] The unfolded phase field is converted into a composite aberration original field that reflects the equivalent optical deformation.

[0021] Optionally, S3 includes:

[0022] Analyze the energy distribution within the shared heat zone to determine the direction of the main energy flow;

[0023] Projecting the original composite aberration field along the main energy flow direction yields a one-dimensional deformation sequence.

[0024] The one-dimensional deformation sequence is trend-fitted to obtain the main trend function of common thermally induced deformation, and the main trend function is mapped back to two-dimensional space to form the main trend deformation field.

[0025] The residual field is obtained by subtracting the principal trend deformation field from the original composite aberration field.

[0026] Optionally, the analysis of energy distribution within the shared thermal zone to determine the direction of the main energy flow includes:

[0027] Spatial gradient calculations are performed on the shared hot zone spatial map to obtain the main energy flow direction field characterizing the direction of maximum local energy accumulation growth.

[0028] Optionally, S4 includes:

[0029] Establish a spatial mapping relationship from the shared hot zone coordinate system to the local coordinate systems of each mirror;

[0030] Based on the order of light reflection, each spatial point within the shared hot zone is assigned a dominant responsible mirror, and independent response zones for the mirrors are constructed.

[0031] Based on the independent response partition of the mirror, the residual field is spatially allocated to obtain the independent residual field of each mirror;

[0032] The independent residual field is structurally consistent to construct a single-mirror attributable aberration field that conforms to the physical constraints of mirror deformation.

[0033] Optionally, the process of assigning a dominant responsibility mirror to each spatial point within the shared hot zone based on the order of light reflection includes:

[0034] For a coordinate point within the shared hot zone, the mirror through which its light rays pass is determined by the spatial mapping relationship, and the mirror encountered first in the light path reflection sequence is selected as the responsible mirror for that point.

[0035] Optionally, S5 includes:

[0036] Based on the intensity of the attributable aberration field of each single mirror and its position in the optical path, the weighting coefficient of its influence on image quality is calculated.

[0037] Multiply the attributable aberration field of each individual mirror by the corresponding weighting coefficient to obtain the weighted mirror deformation field;

[0038] The main trend field is superimposed with all resized mirror deformation fields to generate the final aberration analysis result that combines global aberration distribution and mirror attribution information.

[0039] A second aspect of the present invention discloses a terminal device, including a processor and a storage medium; characterized in that:

[0040] The storage medium is used to store instructions;

[0041] The processor is configured to operate according to the instructions to execute the method described in the first aspect.

[0042] Thirdly, this disclosure provides a computer storage medium storing a computer program that, when executed, implements the method described in the first aspect.

[0043] The beneficial effects of this disclosure are that, compared with the prior art, this disclosure has the following advantages:

[0044] 1) By constructing a spatial energy distribution model of the shared thermal zone of adjacent mirrors, the energy overlap region caused by synchronous heating was effectively identified and quantified, which solved the problem of ambiguity in locating the physical source of aberrations caused by neglecting the thermal coupling effect between mirrors, and provided a precise spatial constraint basis for subsequent analysis.

[0045] 2) The superimposed deformation field is reconstructed within the shared thermal zone and the common thermally induced components are extracted to form a peelable main trend field. This successfully separates the cross-term aberrations that cannot be handled in the traditional aberration attribution model, breaking through the technical bottleneck that caused the mirror adjustment to lose its precise target due to the indivisible composite aberration structure.

[0046] 3) Based on the clearly separated residual field, the independent contribution partitioning of mirrors is performed, and an accurate mapping relationship from observed aberrations to specific responsible mirrors is established. This solves the problem that the system cannot accurately trace the source to a specific mirror after detecting aberrations, and generates a physically reliable single-mirror attributable aberration field.

[0047] 4) By weighted integration of the main trend field and the independent aberration fields of each mirror, a final aberration analysis result with both global and attributional characteristics is generated, which quantifies the relative influence of different aberration components on the system's imaging performance, providing comprehensive and targeted data support for achieving accurate and efficient aberration compensation and ensuring the long-term imaging stability of the system. Attached Figure Description

[0048] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0049] Figure 1 A flowchart of an aberration analysis method for an extreme ultraviolet lithography system provided in an embodiment of this disclosure is shown.

[0050] Figure 2 A schematic diagram of the shared hot zone identification process provided in an embodiment of this disclosure is shown;

[0051] Figure 3A schematic diagram of the aberration field separation and attribution technology path provided in the embodiments of this disclosure is shown.

[0052] The accompanying drawings have illustrated specific embodiments of this disclosure, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this disclosure to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0053] The present disclosure will be further described below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present disclosure more clearly, and should not be used to limit the scope of protection of the present disclosure.

[0054] Extreme ultraviolet (EUV) lithography systems use UV light with a wavelength of approximately 13.5 nanometers as the exposure source. Their optical imaging links typically consist of a multi-mirror system composed of multiple high-precision aspherical mirrors. Since UV light is strongly absorbed in most media, the system must operate in a vacuum environment and rely entirely on reflective optical elements. During long-term, high-frequency continuous operation of the lithography machine, each mirror absorbs light energy and experiences a temperature rise due to continuous exposure to the high-energy UV beam. After several hours of thermal stress, it undergoes slow and minute permanent deformation, known as thermal creep. Particularly noteworthy is that under constant exposure cycle, scanning speed, and illuminance distribution, adjacent mirrors may simultaneously generate significant temperature rises in the same area of ​​the beam. Their respective thermal creeps overlap spatially, forming complex aberration structures that are difficult to attribute to a single mirror, severely limiting the long-term imaging stability of the system. To address the problems of identifying, separating, and attributing these complex aberrations, this disclosure proposes the following aberration analysis method for EUV lithography systems.

[0055] Figure 1 A flowchart of the aberration analysis method for an extreme ultraviolet lithography system provided in this disclosure is shown below. Figure 1 As shown, the process may include the following steps:

[0056] S1: Construct a spatial energy distribution model of the shared hot zone formed by adjacent mirrors under continuous exposure conditions due to synchronous heating.

[0057] When an extreme ultraviolet (EUV) lithography system operates under constant conditions for extended periods, the thermal behavior of each mirror in its multi-mirror chain is not entirely independent. If these shared, synchronously heated regions cannot be identified beforehand, it will be impossible to accurately resolve the complex aberrations caused by overlapping thermal creep. This step, through systematic processing of exposure parameters and spatial energy data, ultimately generates a spatial map of the shared thermal regions with clearly defined physical boundaries, providing an indispensable spatial constraint basis for subsequent aberration removal. Figure 2A flowchart of the shared hot zone identification process in an embodiment of this disclosure is shown, which summarizes the technical path from the input of exposure parameters and energy data to the generation of the final shared hot zone spatial map.

[0058] S1.1: Collect exposure parameters and spatial energy data under continuous exposure conditions to generate the original energy deposition sequence.

[0059] Transforming the macroscopic exposure parameters of a lithography machine into a microscopic, time- and space-varying sequence of energy deposition data is the foundation for constructing the entire energy model. The process begins with acquiring the system's basic exposure parameters, primarily including the exposure cycle time S, the scan speed V, and the illuminance distribution map I(x,y) calibrated by the equipment during factory or periodic calibration. The exposure cycle time S defines the unit cycle duration of a periodic exposure by the lithography machine, typically ranging from 0.1 to 0.5 seconds, determining the basic time unit for energy accumulation. The scan speed V reflects the movement rate of the silicon wafer platform relative to the exposure beam, usually within the range of 200 to 500 mm / s, determining the dwell time of the beam at any specific point on the silicon wafer surface. The illuminance distribution map I(x,y) quantitatively describes the optical power density at each point (x,y) on the beam cross-section, measured in watts per square millimeter; this map is the fundamental basis for calculating spatial energy distribution.

[0060] Based on the above parameters, it is necessary to calculate the energy deposited in the beam sub-region at coordinates (x, y) at any time t. This calculation is performed using the formula... To achieve, among which, I(x,y) represents the transient energy deposition density at time t and coordinates (x,y), measured in joules per square millimeter. D(t) is a crucial time function representing the effective exposure duration at a specific time t. It is directly provided by the lithography machine's cycle control system, and its value dynamically varies between 0 and a complete exposure cycle S. The physical significance of this formula lies in combining the spatial light intensity distribution I(x,y) with the temporal effective exposure duration D(t), achieving spatiotemporal quantification of energy deposition. Through this calculation, we obtain a four-dimensional data sequence E(x,y,t), which fully records the energy received by each point in the lithography machine's field of view at each moment throughout the entire observation period. This provides the most original, unprocessed data source for subsequent analysis of the energy accumulation trend along the mirror link.

[0061] S1.2: Map the energy deposition sequence according to the physical order of the optical path and accumulate it to each mirror to generate an energy accumulation matrix.

[0062] After obtaining the spatiotemporal energy sequence E(x,y,t), this energy data is distributed and accumulated onto each mirror in the multi-mirror link according to the actual physical order of the optical path, thus obtaining the total energy absorption distribution of each mirror within a complete exposure cycle, i.e., the energy accumulation matrix. The optical path of the lithography system is determined. A beam of light emitted from the light source will pass through multiple mirrors numbered 1, 2, ..., m, ..., M in a preset reflection order. In a typical extreme ultraviolet lithography system, M is usually 6. Since the spatial position and attitude angle of each mirror in the optical path are different, the coordinates (x,y) of the same beam of light in the silicon wafer coordinate system need to be mapped onto the local coordinate system of each mirror according to the principles of geometric optics.

[0063] After coordinate mapping is completed, for the m-th reflector, the total accumulated energy H(m,x,y) at its own coordinates (x,y) is calculated by summing all transient energies E(x,y,t) mapped to that point throughout the entire observation period. Its expression is: This summation operation means that, for a specific point on mirror m, all the light rays that passed through that point during the entire exposure process are tracked, and the energy carried by these rays is accumulated. H(m,x,y), in units of joules per square millimeter, visually reflects the total heat absorption at that point after the entire exposure process. Ultimately, for each mirror m, a two-dimensional matrix H(m,x,y) is obtained, which comprehensively depicts the overall energy absorption topography of the mirror surface. This energy accumulation matrix is ​​crucial because it transforms the rapidly changing dynamic exposure process over time into a relatively static, spatially distributed heat load map for each mirror, providing a precise and directly comparable data basis for the next step of finding synchronously heated areas between adjacent mirrors.

[0064] S1.3: Identify and generate a map of common high-energy regions between mirrors by comparing the energy accumulation matrices of adjacent mirrors.

[0065] From the energy accumulation matrices of two adjacent mirrors, precisely locate those spatially overlapping regions with relatively high energy levels. These regions are the physical sources of overlapping thermal creep. In practice, for any pair of adjacent mirrors in the optical path, such as the m-th mirror and the (m+1)-th mirror, perform a pixel-by-pixel comparison analysis of their energy accumulation matrices H(m,x,y) and H(m+1,x,y) calculated in the previous step.

[0066] The common high-energy region map C(x,y) is expressed through mathematical expressions. This formula defines and calculates the common energy value C(x,y) of each spatial coordinate point (x,y). It means that at each point, the smaller of the cumulative energy values ​​of two adjacent mirrors at that point is taken as the common energy value C(x,y). This minimum value operation identifies regions where both mirrors have reached a high energy state. If one mirror has a high energy at a point while the other has a low energy, then that point is not considered a strongly shared heating region.

[0067] After calculating C(x,y), it needs to be screened according to a preset energy threshold to exclude regions with energy too low to trigger a significant thermal effect. This energy threshold is an empirical value determined based on the system's material properties, cooling efficiency, and long-term operating data, typically between 0.2 joules per square millimeter and 0.3 joules per square millimeter. The system compares each pixel of C(x,y) with this threshold, and all points exceeding this threshold are initially marked as candidate segments of the shared thermal zone. These candidate segments may be spatially discrete and discontinuous. Finally, a common high-energy region map containing all these candidate segments is obtained. This map defines the potential region of simultaneous heating of the two mirrors in terms of energy intensity, providing direct evidence for determining the probability of a combined thermal effect and laying the foundation for the final formation of a continuous and complete shared thermal zone map.

[0068] S1.4: Perform energy screening and spatial merging on the common high-energy region map to generate the final shared hot zone spatial map.

[0069] The obtained common high-energy region map C(x,y) has identified pixels with overlapping high energies, but these points may appear isolated and scattered in space, lacking clear physical boundaries, making them difficult to directly guide subsequent aberration analysis. Therefore, these candidate regions need to undergo energy screening, spatial merging, and morphological shaping to generate stable and continuous physical regions, i.e., the final shared thermal zone spatial map.

[0070] In practice, C(x,y) is first subjected to energy threshold screening. Based on the energy threshold (usually between 0.2 joules per square millimeter and 0.3 joules per square millimeter), C(x,y) is converted into a binary candidate region map. When the value of a point in C(x,y) is greater than or equal to this threshold, The value is set to 1 at this point, otherwise it is 0, thus excluding sporadic pixels with too low energy to cause a significant thermal effect.

[0071] Subsequently, the system will process the binary image. Connectivity analysis is performed to identify sets of pixels that are physically connected and form a unified whole. The physical dimensions of these connected regions are evaluated, and their total area is calculated. The system sets an area threshold, typically ranging from 0.05 square millimeters to 0.1 square millimeters, to filter out small, insignificant hotspots. Only contiguous regions exceeding this threshold are retained and considered valid shared hotspots.

[0072] Through a well-designed spatial connectivity filtering function The function performs operations on the connected regions retained after the above filtering process. These operations include image processing such as dilation and erosion to smooth region boundaries and ensure that the final shared hot zones are regular, well-defined, and continuous blocks. The mathematical expression for this process is as follows: Z(x,y) is the final generated shared thermal zone spatial map. It is a binarized or weighted map that explicitly marks all shared thermal zones that simultaneously meet the energy threshold and spatial continuity conditions. This map Z(x,y) has clear physical boundaries and a stable spatial morphology. It will serve as the key input for all subsequent analysis steps, providing a precise spatial framework and constraints for locating, extracting, and analyzing the complex aberration structure composed of overlapping thermal creep in the aberration field.

[0073] In the technical solution of this disclosure, a spatial energy distribution model of the shared thermal zone of adjacent mirrors is constructed, solving the problem of ambiguous aberration source localization caused by neglecting the synchronously heated area. This model transforms the dynamic exposure process into a static spatial thermal load map of each mirror and precisely defines the shared thermal zone with clear physical boundaries. This provides an indispensable and accurate spatial constraint basis for subsequent aberration analysis, enabling the analysis target to focus on the physical source of compound aberrations and avoiding interference from full-field-of-view analysis.

[0074] S2: Based on the spatial energy distribution model, reconstruct the original field of composite aberrations caused by the thermal creep of overlapping adjacent mirrors within the shared thermal zone.

[0075] Based on the physical region defined by the map, the superimposed deformation distribution caused by the thermal creep of adjacent mirror overlaps is reconstructed, i.e., the original field of composite aberrations. This field serves as the fundamental data source for subsequent separation of common trends and independent aberrations. A full-field interferogram sequence is acquired using a wavefront detector on an extreme ultraviolet lithography system, and phase information is extracted and transformed strictly within the shared thermal region to obtain a field distribution reflecting the true physical deformation. The entire process ensures that the analysis focuses on specific regions that may produce composite aberrations, avoiding interference from irrelevant information in the full-field analysis. Figure 3The diagram illustrates the aberration field separation and attribution technology path in this embodiment, demonstrating the data flow and processing logic from the reconstruction of the original composite aberration field, through the extraction of the main trend field and the generation of the residual field, to the final formation of a single-mirror attributable aberration field.

[0076] S2.1: Extract the full-field interferogram based on the shared thermal zone spatial map to obtain the shared thermal zone interferometric sequence.

[0077] The interferogram information, covering the entire optical field of view, acquired by the wavefront detector, is precisely confined to the shared hot zone determined in step S1, thus obtaining an interferometric data sequence containing only potential compound aberration regions. The process begins with obtaining the shared hot zone spatial map Z(x,y) and the full-field interferogram sequence directly acquired by the wavefront detector. .in, It represents the interference light intensity value at time t and spatial coordinates (x, y), and its unit is any relative light intensity unit. It records the full-field wavefront distortion information of the system as it operates over time.

[0078] To perform region capture, the shared hotspot spatial map Z(x,y) first needs to be converted into a binary mask image. This transformation is achieved through a threshold function. To achieve this, that is Specifically, when the value of Z(x,y) is greater than a preset threshold, The output is 1 if the value is positive and 0 otherwise. This threshold is usually set to 10% to 30% of the maximum value of Z(x,y) based on actual processing experience. The purpose is to ensure that only the core shared hot zone with significant energy accumulation and spatial continuity is retained, while excluding edge or weak hot spots.

[0079] Based on the generated binary mask Full-field interferogram at every time t Perform multiplication operations in the spatial domain. Its mathematical expression is: After this calculation, the interferogram that originally covered the entire field of view... The areas that are effectively preserved are limited to The coordinates of points with a value of 1 represent the area inside the shared thermal zone; while the interference intensity values ​​of all coordinates outside the shared thermal zone are set to 0 or ignored. The final result... This is the shared thermal region interferogram sequence. This sequence only contains interferometric intensity information within the shared thermal region. Its physical significance lies in the fact that it strictly constrains subsequent phase analysis within the physical space where overlapping thermal creep may occur, providing a clean and well-defined data foundation for subsequent steps and effectively avoiding interference from aberration information in non-shared thermal regions.

[0080] S2.2: Perform phase demodulation on the shared thermal region interference sequence to obtain the wrapper phase field.

[0081] An interferogram sequence spatially confined to a shared thermal region was obtained. Then, the wrapper phase field containing wavefront phase information is extracted from these interference fringes. The interferogram itself records the distribution of light intensity, while the phase information encodes the distortion of the wavefront and is the direct basis for calculating the mirror distortion. Phase demodulation is a key signal processing step that converts the interference light intensity signal into a phase value.

[0082] In practice, the thermal interference sequence will be shared. The input is fed into a dedicated phase demodulation module. This module performs a series of standardized digital processing steps, typically including frequency domain filtering of the interferogram to suppress noise, normalization of the light intensity to eliminate the effects of illumination inhomogeneities, and finally, calculation of the wrap-around phase using arctangent or other phase extraction algorithms. This series of processes can be performed using a single phase demodulation operator. In summary, its mathematical expression is as follows: .in, This is the output enveloping phase field, measured in radians, representing the wavefront phase distribution at time t within the shared thermal region. It is important to emphasize that due to the periodicity in phase calculations... The value is wrapped in arrive Between, that is, there exists The transition. Phase demodulation operator. Specific parameters, such as the filter bandwidth and normalization coefficient, are typically pre-determined and fixed in the system by the extreme ultraviolet lithography equipment during factory testing or periodic calibration to ensure the accuracy and consistency of phase extraction. This step transforms the raw, intuitive image of interference intensity into phase data that more directly reflects the nature of wavefront distortion, laying the foundation for subsequent recovery of a continuous, true phase field.

[0083] S2.3: Under the shared hot zone constraint, perform phase expansion on the wrapped phase field to obtain the expanded phase field.

[0084] The package phase field obtained from the aforementioned steps Existence with The phase jumps of the modulus do not directly correspond to continuous wavefront deformation in the physical world. Therefore, this step needs to eliminate these phase jumps and recover the true phase field that is continuously distributed within the shared hot zone. This process is called phase unfolding. To avoid introducing uncertainties or erroneous connections outside the boundary of the shared hot zone during phase unfolding, this method specifically utilizes the shared hot zone spatial map Z(x,y) to impose strict spatial constraints on the unfolding process.

[0085] The phase expansion operation is performed through a phase expansion operator. This is achieved by... The input to this operator includes the wrapped phase field to be processed. And the shared hot zone map Z(x,y) as a spatial constraint. Its mathematical expression is: Operator When performing phase unfolding calculations, its internal path planning or least squares algorithm only allows phase value concatenation and integration within the continuous region defined by the shared hotspot map Z(x,y). Specifically, within the shared hotspot, the algorithm iteratively integrates the phase gradient along a reliable path, thereby eliminating... The algorithm performs a phase transition to restore phase continuity; however, outside the shared hot zone boundary, it does not perform any phase connection operations, effectively preventing the incorrect association of phase information within the hot zone with potentially unreliable phase information outside the hot zone.

[0086] The final result This refers to the unfolded phase field within the shared thermal zone. While its unit remains radians, it is now a continuously varying physical quantity within the shared thermal zone. It accurately reflects the true phase deviation of the wavefront relative to the ideal wavefront within the shared thermal zone. By introducing the shared thermal zone constraint, the reliability and physical consistency of the phase unfolding results are ensured, enabling it to accurately characterize the wavefront distortion caused by overlapping thermal creep and providing an accurate phase input for the final conversion into a deformation field.

[0087] S2.4: Convert the unfolded phase field into the original composite aberration field within the shared thermal region.

[0088] The obtained expanded phase field characterizing the wavefront phase change This is transformed into a mirror-equivalent deformation field with clear engineering physical significance, namely the original field of composite aberrations. This field directly quantifies the optical path difference caused by the superposition of thermal creep of adjacent mirrors within the shared thermal zone, and is the direct object for subsequent trend stripping and aberration attribution.

[0089] The conversion process first requires a scaling factor K, which establishes a quantitative relationship between the phase change and the equivalent physical deformation. The scaling factor K is determined by the specific optical path design and operating wavelength of the extreme ultraviolet lithography system, and its dimension is nanometers per radian, representing the change in optical path length corresponding to a unit phase change. K is usually a constant, and its specific value is obtained through specialized system calibration experiments, typically ranging from the nanometer scale to tens of nanometers per radian.

[0090] Since thermal creep is a relatively slow and stable process, in order to extract stable thermally induced deformation features from the instantaneous phase field, which may contain random fluctuations or noise, it is necessary to average the unfolded phase in the time dimension. A time averaging operator is defined. The operator operates within a preset stable operating time window. Time averaging is performed. The length of this time window is set according to the thermal stability of the equipment, typically ranging from several minutes to tens of minutes, to ensure that short-term fluctuations are smoothed out while preserving long-term thermal creep trends. The average phase field within the shared thermal zone... Calculated using the following formula: . The unit is radians, which represents the average optical deformation caused by thermal effects at each coordinate point (x,y) within the shared thermal zone over a period of time.

[0091] Finally, the average phase field Multiplying by the scaling factor K yields the original field of the composite aberrations. Its calculation formula is ,in, The unit is nanometer. It is a two-dimensional field defined within the shared thermal zone, quantitatively describing the stable equivalent optical deformation distribution caused by the combined effect of thermal creep of adjacent mirrors. This field is named the composite aberration primitive field because it does not yet distinguish the independent contributions of different mirrors, but rather includes the mixed effect of the thermally induced deformation of the two mirrors. This field is the only reliable starting point for subsequent steps to extract the common thermal trend and separate independent mirror aberrations, and its accuracy directly determines the success or failure of the entire aberration analysis process.

[0092] In the technical solution of this disclosure, based on a shared thermal zone spatial map, the superimposed deformation field caused by overlapping thermal creep, i.e., the original field of composite aberrations, is reconstructed. By strictly limiting the extraction and transformation of wavefront phase information within the shared thermal zone, interference from aberration information in non-shared thermal zones is effectively eliminated, ensuring the purity and clarity of the analysis data. This step yields a stable field distribution reflecting the true physical deformation, providing a unique and reliable data starting point for the subsequent accurate separation of common trends and independent aberrations.

[0093] S3: Extract the main trend field composed of the common thermal deformation of adjacent mirrors from the original composite aberration field, and subtract the main trend field from the original composite aberration field to separate the residual field characterizing the independent deformation contribution of the mirrors.

[0094] From the raw composite aberration field obtained in step S2, the dominant trend deformation component, spatially correlated and caused by the shared heating of adjacent mirrors, is extracted. This dominant trend deformation represents the common backbone structure of overlapping thermal creep and is independent of the independent deformation characteristics of individual mirrors. By accurately extracting and removing this common component, a clean residual field can be provided for subsequent attribution analysis of independent mirror aberrations. The entire process relies on the analysis of the dominant direction of energy distribution within the shared thermal zone and trend modeling along this direction.

[0095] S3.1: Perform spatial gradient analysis based on the energy distribution of the shared thermal zone to obtain the main energy flow direction field.

[0096] To accurately extract the common trend in composite aberrations, it is first necessary to determine the dominant spatial direction of energy accumulation and heat load transfer within the shared thermal zone. This dominant energy flow direction reveals the spatial axis along which thermal effects are most likely to produce cooperative deformation between adjacent mirrors. Based on the energy distribution information contained in the shared thermal zone spatial map Z(x,y), this directional field is solved through spatial gradient analysis.

[0097] In practice, spatial gradient calculations are performed on the shared hotspot spatial map Z(x,y). Gradient calculations reveal the direction of the most dramatic change in Z(x,y) at each coordinate point (x,y). This direction represents the maximum increase in local energy accumulation and is closely related to the main path of light propagation and absorption in that region. A gradient calculation operator is defined. The parameters of this operator are obtained by calibration using the system's optical path geometry model. It can handle the spatial distribution of Z(x,y) and output the main energy flow direction field D(x,y). Its mathematical expression is as follows: .

[0098] The main energy flow direction field D(x,y) is itself a vector field. At each coordinate point (x,y) belonging to the shared heat zone, it uses a unit direction vector to represent the main energy flow direction at that point. This vector can usually be decomposed into two components: This indicates the horizontal component of the mainstream. The dominant energy flow direction field D(x,y) represents the longitudinal component of the mainstream direction, both of which are dimensionless unit vector components. The obtained dominant energy flow direction field D(x,y) provides a crucial geometric basis for subsequent trend analysis by projecting the two-dimensional deformation field onto the one-dimensional dominant direction.

[0099] S3.2: A one-dimensional deformation sequence is obtained by directional projection of the original composite aberration field along the main energy flow direction.

[0100] After clarifying the main energy flow direction field D(x,y), the two-dimensional composite aberration original field is... The deformation information in the data is compressed and projected along the dominant direction to obtain a one-dimensional sequence that reflects the general deformation changes along the heat flow path. This projection operation effectively reduces the data dimensionality, highlights the deformation characteristics along the main heat-affected path, and facilitates subsequent global trend fitting.

[0101] The specific implementation process involves a directional projection operator. The function of this operator is to, based on the guidance defined by the main energy flow direction field D(x,y), determine the deformation values ​​at all coordinate points (x,y) within the shared thermal region. They are then categorized and aggregated according to their position parameters in the dominant direction. First, a path coordinate s needs to be established along the main energy flow direction D(x,y). The coordinate s represents the position in the dominant direction, and its unit is usually millimeters. Its value range covers the entire shared heat zone projected along this direction.

[0102] The projection process can be represented as .here, This is the obtained principal direction projection sequence. Each value in this sequence... This represents the deformation values ​​at direction coordinate s, all perpendicular to that direction and located within a narrow band. A certain aggregation, such as the mean or median. Through this operation, the complex aberration field originally distributed in a two-dimensional plane is transformed into a one-dimensional deformation intensity sequence that varies along the main heat flow path s. This sequence clearly shows how deformation evolves along the most important thermal influence path, preparing the ground for the next step of extracting the slowly changing common trend components.

[0103] S3.3: Perform trend fitting on the one-dimensional deformation sequence and map the results back to two-dimensional space to form the main trend deformation field.

[0104] Obtain a one-dimensional deformation sequence along the main energy flow direction Subsequently, a smooth, slowly changing trend component is extracted from the sequence, and this trend is defined as the main trend of the common thermally induced component. Since overlapping thermal creep is caused by synchronous, cumulative thermal loads, the resulting deformation should exhibit low-frequency, continuous characteristics in space, while high-frequency fluctuations usually originate from measurement noise or local irregularities of the mirror itself. The purpose of trend fitting is to separate this low-frequency common backbone structure.

[0105] This process is achieved through a trend fitting operator. This is achieved by using an operator designed to extract smooth, slowly changing components from input data. Specific algorithm parameters, such as the order of the fitting polynomial and the bandwidth of the smoothing filter, are set by the system's thermal stability model to ensure that the extracted trend conforms to the physical characteristics of thermal creep. The mathematical expression for trend fitting is... .in, It is the main trend function obtained by fitting. It is a one-dimensional function with respect to the direction coordinate s, and its unit is the same as that of the deformation field, which is nanometers. The basic deformation profile caused by the joint thermal creep of the two mirrors along the main energy flow direction s is depicted, while ignoring the local details and undulations along the path.

[0106] As an optional implementation, the trend fitting operator Different implementation algorithms can be selected based on the spatial characteristics of the shared thermal zone. For shared thermal zones with regular shapes and smooth energy distribution, second-order or third-order polynomial fitting algorithms can be used, which are computationally efficient and can effectively capture the basic thermal deformation profile. For shared thermal zones with complex boundaries or abrupt changes in energy distribution, spline fitting algorithms based on regularization constraints are preferred, as these algorithms can better adapt to local deformation characteristics while maintaining trend smoothness. In practical applications, the system can automatically select the fitting algorithm based on the geometric complexity of the shared thermal zone map Z(x,y) to achieve the best balance between accuracy and efficiency.

[0107] Obtain the one-dimensional main trend function Then, it needs to be remapped back to the two-dimensional shared hot zone space to form the two-dimensional principal trend deformation field T(x,y). This mapping is performed through a direction-to-plane mapping operator. This is accomplished by using the previously obtained main energy flow direction field D(x,y) to transform the one-dimensional trend value. Based on the path coordinates s of each two-dimensional coordinate point (x, y) along its dominant direction D(x, y), a corresponding spatial position is assigned, and the relationship is expressed as follows: The final dominant deformation field T(x,y) is a two-dimensional distribution, where the value T(x,y) at each point (x,y) within the shared thermal zone represents the dominant deformation caused by the common thermal component at that location. This field is the key outcome of the entire process, quantifying the cooperative deformation spatial structure generated purely by overlapping thermal effects, independent of the individual characteristics of the mirrors.

[0108] S3.4: Subtract the principal trend deformation field from the original composite aberration field to form the residual aberration field for mirror attribution.

[0109] By using simple difference operations, the extracted common main trend components are stripped from the original composite aberration field, resulting in a residual aberration field. This residual field is considered to mainly contain the individual deformation contributions of individual mirrors, as well as any residual noise, while the common thermally induced trend has been removed to the greatest extent possible.

[0110] In practice, at each spatial coordinate point (x, y) within the shared hot zone, a point-to-point subtraction operation is performed: the value of the main trend deformation field T(x, y) is subtracted from the original composite aberration field. Subtract from the value. This calculation is done using the formula. Define, where, This is the calculated residual aberration field, whose unit is the same as the input field, which is nanometers. This represents the remaining deformation distribution within the shared thermal zone after the removal of the main deformation structure caused by the shared thermal creep of adjacent mirrors. Theoretically, this residual field no longer contains spatial patterns strongly correlated with the synchronous heating of the two mirrors; the deformation information it contains is more likely derived from independent thermomechanical responses caused by differences in the material, supporting structure, or local cooling conditions of each mirror. Therefore, The accuracy of the input directly determines whether subsequent steps can successfully attribute aberrations to a specific responsible mirror. It is the only reliable input for performing mirror-independent contribution partitioning operations, ensuring the clarity and feasibility of aberration source analysis.

[0111] The technical solution of this disclosure effectively separates the spatially correlated main trend deformation component caused by the common heating of adjacent mirrors from the original field of composite aberrations. By introducing the analysis of the main energy flow direction and trend modeling along this direction, the mixed composite aberrations are decomposed into the common backbone structure and the independent contributions of the mirrors. This solves the problem of inseparable cross terms in traditional aberration attribution models and lays the foundation for clearly and accurately attributing residual aberrations to specific responsible mirrors.

[0112] S4: Based on the optical path geometry and the order of light reflection, the deformation in the residual field is distributed to the corresponding responsible mirror to form a single-mirror attributable aberration field.

[0113] After successfully extracting the dominant trend field characterizing the common thermally induced deformation, the residual aberration field obtained in step S3 is precisely assigned back to each mirror in the optical path, forming an attributable aberration field independently corresponding to each mirror. Based on the inherent geometry and optical path sequence of the lithography system, a mapping relationship is established from the shared thermal region coordinate system to the coordinate system of each mirror itself. Based on the physical order of light reflection, the responsible mirror is determined for each deformation point in the residual field. Finally, through physical consistency correction of the assignment results, a single-mirror aberration field that can be used to guide active mirror compensation is obtained.

[0114] S4.1: Establish the spatial mapping relationship from the shared hot zone coordinate system to the local coordinate systems of each reflector.

[0115] To trace the residual deformation field observed in the shared hot zone coordinate system back to the specific responsible mirror, it is first necessary to establish a precise spatial transformation relationship from the shared hot zone coordinate system to the local coordinate system of each mirror. This mapping relationship takes into account the unique mounting position and orientation of each mirror within the optomechanical system. The process begins by obtaining the spatial position matrix of each mirror. Where m is the number of the reflecting mirror, and in a typical six-mirror system, m ranges from 1 to 6. Position matrix It includes the key parameter for defining the m-th mirror space state: the lateral position of the mirror center. The vertical position of the center of the mirror The unit is millimeters, and the direction angle of the mirror normal vector in the system's global coordinate system. Its unit is usually degrees.

[0116] Based on these position and attitude parameters, and combined with optical path geometry information such as the incident angle of the beam, a mirror space mapping operator is defined. This operator encapsulates the coordinate transformation algorithm determined by system installation data and the optical path tracing model. For any coordinate point (x, y) within the shared hot zone, the mapping operator... It is possible to calculate its corresponding coordinates (u, v) in the local coordinate system of the m-th mirror. This mapping relationship is expressed as: Output It is a mapping field containing two components (u,v), which precisely describes which point (u,v) on the m-th mirror surface a point (x,y) in the shared hot zone originates from. Establishing this precise spatial mapping relationship is the geometric basis for correctly tracing observed aberrations back to their generating mirror surface.

[0117] S4.2: Based on the order of light reflection, divide each point in the shared hot zone into its dominant responsible mirror to construct an independent response zone for the mirror.

[0118] After establishing an accurate spatial mapping, it is necessary to determine which mirror's contribution area each point within the shared thermal zone should belong to, based on the physical order of light propagation and reflection in the optical path. Although an object point may be reflected sequentially by multiple mirrors, its final optical path error is usually considered to be mainly dominated by the deformation of a certain mirror, or a clear attribution based on the reflection order is needed to avoid double-counting of aberration contributions.

[0119] To achieve this, it is necessary to introduce a sequence of light reflections. It specifies the sequential numbering order in which light rays pass through the mirrors. A mirror response partitioning operator is defined. The input to this operator includes the aforementioned coordinate mapping field. and the order of light reflection Operator The execution logic is as follows: For a coordinate point (x, y) within the shared hot zone, firstly through... Determine which mirrors the light source originates from; then, based on the order of light reflection... The mirror encountered first in the light path is chosen as the responsible mirror at that point. Its mathematical expression is: .

[0120] Output This is the independent response partition map of mirror m; it is a binary field with values ​​of 0 or 1. When When =1, it means that the residual aberration at the coordinate point (x,y) of the shared hot zone is assigned to the m-th mirror. Through this partitioning operation, the entire shared hot zone is divided into several non-overlapping regions, each region uniquely corresponding to a mirror, clearly defining the independent contribution space of each mirror to the final composite aberration.

[0121] S4.3: Spatially allocate the residual field according to the independent response partition of the mirror to obtain the independent residual field of each mirror.

[0122] After clarifying the independent response partition corresponding to each mirror Then, the residual field obtained in step S3 is... Spatial allocation is performed according to the partitioning results, thereby generating an independent residual field for each mirror containing only its assigned deformation value. The allocation process is implemented through mask multiplication in the spatial domain. For the m-th mirror, its independent residual field... Calculated using the following formula: .because It is a binary mask, and the operation is performed within the response partition belonging to mirror m, i.e. The area The value is equal to the original residual field. The value; while in all other regions, The value is set to zero.

[0123] Through this operation, the residual fields that were originally mixed together and characterized the independent deformation of the mirror surface are separated. It was successfully decomposed into a series of fields Each of the fields Spatially, these independent residual fields retain non-zero values ​​only within their respective mirror response regions. These fields quantitatively depict the share of each mirror's own thermally induced deformation within a shared thermal region, serving as a direct precursor to constructing a physically reliable single-mirror aberration field that can ultimately be used for compensation.

[0124] S4.4: Perform structural consistency correction on the independent residual fields of each mirror to construct the final attributable aberration field for a single mirror.

[0125] Independent residual fields obtained directly from partition allocation It may contain high-frequency fluctuations or spatial noise that do not conform to the actual structural mechanical properties of the mirror, which may originate from measurement noise or calculation errors. To generate an aberration field that is more physically realistic and has greater engineering guidance, it is necessary to... Spatial consistency correction is performed to ultimately form a single-mirror attributable aberration field. .

[0126] This correction is achieved through a structural consistency correction operator. This is achieved through an understanding of the stiffness, material properties, and typical deformation modes of the mirror support structure. Its function is to filter out… The correction operation identifies local singular values ​​or high-frequency components that are physically impossible or highly unlikely to be generated by mirror thermal creep, while preserving a smooth distribution consistent with low-order deformation modes such as overall mirror bending and torsion. The correction operation is represented as... .

[0127] Obtained This is the final attributable aberration field of the m-th mirror, measured in nanometers. This field not only includes estimates of the mirror's independent thermally induced deformation within the shared thermal region, but its spatial morphology also satisfies the deformation constraints of the mirror as a continuous elastic body under specific support conditions, thus possessing higher physical reliability and engineering feasibility. These single-mirror attributable aberration fields... It provides accurate, reliable, and object-oriented input for the final aberration analysis results of the synthesized system and for driving the mirror compensation action.

[0128] In the technical solution of this disclosure, based on a clear residual field, aberrations are precisely allocated back to each reflecting mirror according to the optical path geometry and the order of light reflection, forming an attributable aberration field for each single mirror. By establishing a precise spatial mapping relationship and physical consistency correction, the generated aberration field not only quantifies the independent thermal deformation contribution of each mirror, but its spatial shape also conforms to the deformation constraints of the mirror as a continuous elastic body. This provides a reliable and object-oriented direct input for accurate aberration tracing and subsequent compensation actions for specific mirrors.

[0129] S5: Assign weights to each of the attributable aberration fields of a single mirror based on their impact on image quality, and synthesize the weighted aberration fields of each mirror with the main trend field to generate the final aberration analysis result for aberration compensation.

[0130] The results obtained in the preceding steps—namely, the main trend field characterizing the common thermally induced deformation—are weighted and integrated with a series of aberration fields characterizing the independent contributions of each mirror, generating a complete, quantitative, and directly applicable final aberration analysis result for control system compensation. This result not only reflects the overall spatial distribution of aberrations but also precisely quantifies the relative impact of different mirror aberrations on the system's imaging performance, thus providing comprehensive and targeted data support for the formulation of aberration compensation strategies.

[0131] S5.1: Calculate the corresponding weighting coefficient based on the degree of influence of each mirror aberration field on the imaging quality.

[0132] Before synthesizing the final aberration field, it is essential to recognize that the surface deformation of mirrors at different locations in the optical path has varying degrees of impact on the final wafer imaging quality, such as focus drift, resolution degradation, and contrast deterioration. This step assigns appropriate weighting coefficients to the independent aberration fields of each mirror to reflect these differences in physical influence during the final synthesis.

[0133] The specific implementation relies on a mirror effect calculation operator. The input to this operator is the attributable aberration fields of each single mirror obtained in step S4. Operator Based on a fixed algorithm determined by the system's optical sensitivity standards, multiple factors of each mirror aberration field are comprehensively evaluated. These factors typically include the overall intensity of the mirror aberration, such as the root mean square value; the mirror's position in the optical path (generally, the closer the mirror is to the image plane, the greater the impact of unit deformation on image quality); and the coupling relationship between the spatial frequency distribution of the aberration and the imaging system's transfer function. Through comprehensive calculation of these factors, a weighting coefficient is assigned to each mirror m. Its calculation formula is .

[0134] Output It is a scalar, and its value is usually set between 0.1 and 1. A higher... The value indicates that the aberration of the m-th mirror has a relatively more significant impact on the system's imaging performance, and its contribution will be emphasized in subsequent synthesis. The introduction of this weighting coefficient ensures that the final synthesized aberration analysis result is not merely a simple superposition of deformation variables, but a true reflection of the degree of impact on imaging quality, thus providing a quantitative basis for establishing compensation priorities.

[0135] S5.2: Apply weighting coefficients to each mirror aberration field to obtain a weighted mirror deformation field that reflects its relative importance.

[0136] After obtaining the weight coefficients for each mirror... Next, a weighting operation is performed to convert the weights into the actual contribution magnitude of each mirror aberration field in the final synthesis. This process is achieved through simple scalar multiplication; for the m-th mirror, its single-mirror attributable aberration field is multiplied. With the corresponding weighting coefficients Multiplying them together yields the weighted aberration field of the mirror. Its mathematical expression is: After weighting, The field, numerically representing not only the physical deformation of the m-th mirror, but also the importance of that deformation to system performance, is considered. For a mirror with a large deformation but a low weight, its weighted field... This is comparable to the contribution of a mirror with a small deformation but a high weight. It maps the abstract degree of influence to the deformation space distribution of each mirror through weight coefficients, generating a series of weighted mirror deformation fields that can more directly guide compensation decisions, thus preparing the data for the final synthesis.

[0137] S5.3: Overlay the main trend deformation field with all resized mirror aberration fields to generate the final aberration analysis results of the system.

[0138] The dominant trend deformation field T(x,y), representing the common thermotropic component, is combined with the weighted independent mirror aberration field. Spatial overlay is performed to generate The composition operation is accomplished through linear superposition, and its calculation formula is as follows: The final result It is a two-dimensional aberration field defined within a shared thermal region, measured in nanometers. It comprehensively encompasses all aberration components within the analyzed region, including:

[0139] The indivisible common trunk deformation T(x,y) is generated by the thermal creep of adjacent overlapping mirrors.

[0140] The deformation contributed by the independent thermal creep of each mirror surface, weighted according to its imaging influence. .

[0141] Should The field represents the final aberration analysis result output by this method. It possesses both global and attributional characteristics, describing both the overall severity and spatial distribution of aberrations, while also inherently distinguishing the contributions and relative importance of common components and independent components of each mirror. Based on this result, the control system can drive corresponding actuators for focusing, shaping, or regional thermal management, achieving precise and efficient compensation for complex aberrations, thereby effectively maintaining the imaging quality and stability of the extreme ultraviolet lithography system during long-term operation.

[0142] In the technical solution of this disclosure, a complete and directly applicable final aberration analysis result is generated by weighted integration of the main trend field and the independent aberration fields of each mirror. By introducing weighting coefficients based on the degree of imaging influence, the synthesized result not only reflects the overall spatial distribution of aberrations but also realistically quantifies the relative differences in the impact of different mirrors on the system's imaging performance. This result provides comprehensive and targeted data support for the formulation of aberration compensation strategies, enabling the control system to perform efficient and accurate compensation based on the guidance of the results, ultimately ensuring the long-term imaging stability of the system.

[0143] In summary, this invention effectively identifies and quantifies the energy overlap region caused by synchronous heating by constructing a spatial energy distribution model of the shared thermal zone of adjacent mirrors. This solves the problem of ambiguous location of the physical source of aberrations caused by neglecting the thermal coupling effect between mirrors, providing a precise spatial constraint basis for subsequent analysis. By reconstructing the superimposed deformation field within the shared thermal zone and extracting common thermally induced components to form a peelable main trend field, it successfully separates cross-term aberrations that cannot be handled in traditional aberration attribution models, overcoming the technical bottleneck of losing precise targets for mirror shaping due to the indivisible structure of composite aberrations. Based on the clearly separated residual field, it performs independent contribution partitioning of mirrors, establishing an accurate mapping relationship from observed aberrations to specific responsible mirrors. This solves the problem that the system cannot accurately trace the source of aberrations to specific mirrors after detection, generating a physically reliable single-mirror attributable aberration field. By weighted integration of the main trend field and the independent aberration fields of each mirror, a final aberration analysis result with both global and attributional characteristics is generated. This quantifies the relative impact of different aberration components on the system's imaging performance, providing comprehensive and targeted data support for achieving accurate and efficient aberration compensation and ensuring the long-term imaging stability of the system.

[0144] According to embodiments of this disclosure, an electronic device is also provided, which may include a processor, a communications interface, a memory, and a communication bus, wherein the processor, the communications interface, and the memory communicate with each other via the communication bus. The processor can invoke logical instructions stored in the memory to execute the methods provided by the above methods.

[0145] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, and can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this disclosure, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this disclosure. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0146] On the other hand, this disclosure also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the methods provided by the above methods.

[0147] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0148] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0149] It should be understood that the above embodiments are only used to illustrate the technical solutions of this disclosure, and not to limit them; although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A method of aberration analysis of an extreme ultraviolet lithography system, characterized in that, The method includes: S1, Construct a spatial energy distribution model of the shared hot zone formed by the synchronous heating of adjacent mirror surfaces under continuous exposure conditions; S2, Based on the spatial energy distribution model, reconstruct the original field of composite aberrations caused by the thermal creep of overlapping adjacent mirrors within the shared thermal zone; S3, extract the main trend field composed of the common thermal deformation of adjacent mirrors from the original composite aberration field, and subtract the main trend field from the original composite aberration field to separate the residual field characterizing the independent deformation contribution of the mirrors; S4. Based on the optical path geometry and the order of light reflection, the deformation in the residual field is distributed to the corresponding responsible mirror to form a single-mirror attributable aberration field. S5, assign weights to each of the single-mirror attributable aberration fields based on their impact on image quality, and synthesize the weighted aberration fields of each mirror with the main trend field to generate the final aberration analysis result for aberration compensation.

2. The method for aberration analysis of the extreme ultraviolet lithography system according to claim 1, characterized in that, S1 includes: Exposure parameters and spatial energy data are collected to generate an energy deposition sequence, and this sequence is mapped and accumulated to each mirror according to the physical order of the optical path to generate an energy accumulation matrix for each mirror. By comparing the energy accumulation matrices of adjacent mirrors, a common high-energy region map between mirrors can be identified and generated. Energy filtering and spatial merging are performed on the common high-energy region map to generate a shared thermal zone spatial map with clear physical boundaries.

3. The method for aberration analysis of the extreme ultraviolet lithography system according to claim 2, characterized in that: The generation of the energy deposition sequence includes: determining the effective exposure duration based on the exposure cycle, scan speed, and illuminance distribution map, and calculating the transient energy deposition density at time t and spatial coordinates (x, y). .

4. The method for aberration analysis of the extreme ultraviolet lithography system according to claim 2, characterized in that, S2 includes: Based on the shared thermal zone spatial map, the shared thermal zone interference sequence is extracted from the full-field interferogram; The shared hot zone interference sequence is sequentially subjected to phase demodulation and phase expansion to obtain the expanded phase field within the shared hot zone; The unfolded phase field is converted into a composite aberration original field that reflects the equivalent optical deformation.

5. The method for aberration analysis of the extreme ultraviolet lithography system according to claim 4, characterized in that, S3 includes: Analyze the energy distribution within the shared heat zone to determine the direction of the main energy flow; Projecting the original composite aberration field along the main energy flow direction yields a one-dimensional deformation sequence. The one-dimensional deformation sequence is trend-fitted to obtain the main trend function of common thermally induced deformation, and the main trend function is mapped back to two-dimensional space to form the main trend deformation field. The residual field is obtained by subtracting the principal trend deformation field from the original composite aberration field.

6. The method for aberration analysis of the extreme ultraviolet lithography system according to claim 5, characterized in that, The analysis of energy distribution within the shared thermal zone to determine the main energy flow direction includes: performing spatial gradient calculations on the spatial map of the shared thermal zone to obtain the main energy flow direction field characterizing the direction of maximum local energy accumulation growth.

7. The method for aberration analysis of the extreme ultraviolet lithography system according to claim 6, characterized in that, S4 includes: Establish a spatial mapping relationship from the shared hot zone coordinate system to the local coordinate systems of each mirror; Based on the order of light reflection, each spatial point within the shared hot zone is assigned a dominant responsible mirror, and independent response zones for the mirrors are constructed. Based on the independent response partition of the mirror, the residual field is spatially allocated to obtain the independent residual field of each mirror; The independent residual field is structurally consistent to construct a single-mirror attributable aberration field that conforms to the physical constraints of mirror deformation.

8. The method for aberration analysis of the extreme ultraviolet lithography system according to claim 7, characterized in that, The method of assigning a dominant responsible mirror to each spatial point within the shared hot zone based on the order of light reflection includes: for a coordinate point within the shared hot zone, determining the mirror through which its light passes by using the spatial mapping relationship, and selecting the mirror encountered first in the light path reflection order as the responsible mirror for that point.

9. The method for aberration analysis of the extreme ultraviolet lithography system according to claim 8, characterized in that, S5 includes: Based on the intensity of the attributable aberration field of each single mirror and its position in the optical path, the weighting coefficient of its influence on image quality is calculated. Multiply the attributable aberration field of each individual mirror by the corresponding weighting coefficient to obtain the weighted mirror deformation field; The main trend field is superimposed with all resized mirror deformation fields to generate the final aberration analysis result that combines global aberration distribution and mirror attribution information.

10. A terminal device, comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform a method for aberration analysis of an extreme ultraviolet lithography system according to any one of claims 1-8.

11. A computer storage medium, characterized in that, It stores a computer program, which, when executed, performs a method for aberration analysis of the extreme ultraviolet lithography system according to any one of claims 1-9.

Images