Controlling relative position of moveable target and charged-particle beams in multi-column exposure apparatus

Abstract

To provide approaches for measuring a target and beam column positioning.SOLUTION: For controlling relative positioning of a moveable target and a charged-particle beam array, in a charged-particle multi-beam processing apparatus, a distance measurement system is employed which includes an interferometer system employing two sets of interferometer beams (X1,X2;Y1,Y2) for measurements along different directions in a measuring plane. When a target is moved through a sequence of target movement positions, at each position the distance measurement system measures a current position of the target with respect to reference measuring points (55, 56) in the measuring plane. A target deviance, which describes deviation of a position and orientation of the target from a nominal target movement position and orientation, is calculated. Further, deviation amounts for particle-optical columns, describing deviation of a location of a base point of the columns, and respective beam displacements for beams of the particle-optical columns which compensates the respective deviation amount, applied via a deflection system of the particle-optical columns are determined.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This application claims the benefit of Paris Convention priority of European Patent Application No. 24175161.9, filed May 10, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to some improvements in the control of charged particle beam and moving target positioning in a multi-column charged particle exposure apparatus. [Background technology]

[0003] The applicant has developed a charged particle multi-beam device, corresponding charged particle optical components, a pattern definition device, and a writing method for the multi-beam device, and has commercialized a 50 keV electron multi-beam writer called eMET (electron Mask Exposure Tool) or MBMW (multi-beam mask writer) that can be used to write any photomask for 193 nm immersion lithography, masks for EUV lithography, and templates for nanoimprint lithography. The applicant's system is also called PML2 (Projection Mask-Less Lithography) for electron beam direct writer (EBDW) applications on substrates. Further details can be found, for example, in the applicant's patents U.S. 9,053,906, U.S. 9,520,268, U.S. 6,768,125, U.S. 8,222,621, and U.S. 8,378,320. The disclosures of these documents are incorporated herein by reference.

[0004] Furthermore, the applicant has developed a multi-column exposure apparatus for direct writing applications to 12-inch (12") wafers or 6-inch (6") photomasks in US 7,214,951 and US 9,443,699 B2. The disclosures of these documents are incorporated herein by reference. An example of a typical multi-column system includes multiple charged particle optical sub-columns, each of which includes an illumination system that delivers a wide, telecentric charged particle beam to a pattern definition system and then to a charged particle projection optical system. The projection optical system includes, for example, multiple electrostatic and / or electromagnetic lenses. Furthermore, the applicant's US 2023 / 0015805 A1 provided a "slim" lens optimized for multi-column applications that enables a multi-column system with increased current and throughput. The disclosures of US 2023 / 0015805 A1 are incorporated herein by reference. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US9,053,906 [Patent Document 2] US9,520,268 [Patent Document 3] US6,768,125 [Patent Document 4] US8,222,621 [Patent Document 5] US$8,378,320 [Patent Document 6] US7,214,951 [Patent Document 7] US9,443,699B2 [Patent Document 8] US2023 / 0015805A1 Summary of the Invention [Problem to be solved by the invention]

[0006] During the writing process in such a charged particle device, the substrate is positioned on a target stage. The target stage continuously moves the substrate in a target plane according to a predetermined path to expose the entire exposure area on the substrate to the charged particle beam(s). To this end, the movable substrate is moved by the target stage through a series of target motion positions. However, the target stage typically has an inherent mechanical positioning accuracy that is much smaller than the desired accuracy of the positioning of the beam images on the substrate. In the prior art, one approach to correct this limited accuracy is to shift the position of the beams using the charged particle projection optics, in particular deflection units such as electrostatic multipole lenses in the projection optics. While this approach is often effective, as the applicant has realized, it is hampered by the inherent misalignment of the beam columns themselves, which, both absolutely and with respect to their relative positions, is often significantly larger than the allowable accuracy of the positioning of the beam images.

[0007] It is an object of the present invention to provide an approach for measuring a target and positioning a beam column, in particular for positioning a beam image that is written with extremely high precision on a target by the beam column. [Means for solving the problem]

[0008] According to a first aspect of the present invention, there is provided a method of controlling the relative positioning of a movable target and a charged particle beam array, comprising: the charged particle beam array includes a plurality of charged particle beams generated by a plurality of particle optical columns in a charged particle multi-beam processing apparatus for exposure of a target; the target is moved through a predetermined series of target movement positions within a target plane using a target stage of the charged particle multi-beam processing apparatus; the plurality of particle-optical columns are arranged along respective longitudinal axes that transverse (pass through) the target surface at respective base points, and each particle-optical column is configured to generate a respective charged particle beam and project it onto the target in a respective region around the respective base point to generate a pattern sub-image in that region according to a pattern to be exposed on the target; The method comprises: providing the charged particle multi-beam processing apparatus including the plurality of particle optical columns; Providing distance measurement systems (ranging systems); and measuring the current position of the target using the distance measurement system; performing repositioning of the charged particle beam of the particle optical column based on the current position of the target; Including, the distance measurement system is configured to measure positions of at least two predetermined reference measurement points of the target within the target stage in a measurement plane that is coincident with or substantially parallel to the target surface; the measurement results of the position of the reference measurement point are used to calculate the actual position and orientation of the target and to derive a target deviance representing the deviation of the actual target position and orientation from its associated nominal target motion position and orientation; performing repositioning of the charged particle beam of the particle optical column based on the current position of the target, controlling the target stage to move to a corrected position to compensate for the target misalignment; and calculating beam displacements for the particle optical columns within the charged particle beam array, each of the beam displacements representing a position correction for a position of a respective fiducial point of a respective particle optical column that compensates for a target shift applied to the respective fiducial point; At least one of the following must be included: It is characterized by: DETAILED DESCRIPTION OF THE INVENTION

[0009] (Mode 1) See the first aspect of the present invention above. (Mode 2) In the method of mode 1, The method further includes a fine position adjustment method for a systematic error of the distance measurement system; The fine position adjustment method includes: obtaining a position error map, wherein the position error map represents position errors in the distance measurement system as a function of respective positions; distance measurements along a plurality of coordinate values ​​from the distance measurement system; To get TIFF2025186168000002.tif6150, Correcting the distance measurements using the position error map to obtain adjusted distance measurements Obtain TIFF2025186168000003.tif6150, and The adjusted distance measurements are used to determine the center position of the target stage or target. TIFF2025186168000004.tif6150 and azimuth angle Determine the center data, including TIFF2025186168000005.tif6150 Including is preferred. (Mode 3) In the method of mode 2, The fine position adjustment method includes: transmitting the center data to a stage control unit for correction of the position of the target stage or target. Further comprising is preferred. (Mode 4) In the method of mode 2 or 3, Distance measurements along multiple coordinate values The step of acquiring TIFF2025186168000006.tif6150 is performed only for a plurality of predetermined crossing points, and the crossing points have extremal values ​​of coordinates in the distance measurement system. is preferred. (Mode 5) In any of the methods of modes 2 to 4, The position error map used in the fine position adjustment method is performing an exposure on a test substrate with a calibration pattern including an array of alignment markers and processing the test substrate; determining the position of the alignment marker; obtaining positional displacements of the alignment markers relative to their respective nominal positions; and generating a position error map from said position displacements; To be determined by is preferred. (Mode 6) In the method of mode 5, in the step of performing exposure on the test substrate, exposure of said alignment markers is performed using said particle optical columns, each particle optical column using its pattern definition device to define a pattern sub-image that depicts its alignment marker; Only a center portion of the pattern definition device is used for exposure of the alignment markers. is preferred. (Mode 7) In any of the methods of modes 1 to 6, the position of the particle-optical column origin is determined using an initial calibration process; In the initial calibration process, a test substrate is exposed by a writing process in which each of the particle optical columns writes a test pattern onto the test substrate; The position of the test pattern is measured; The positions so measured are compared with the nominal positions of the respective particle-optical columns and the deviations from said nominal positions are stored. is preferred. (Embodiment 8) In the method of embodiment 7, The test patterns are copies of a template pattern, the template pattern including a pattern shape, such as a cross or a star, having multiple components radially arranged around a central location. is preferred. (Mode 9) In any of the methods of modes 1 to 8, calculating the beam displacement includes, for each particle-optical column, measuring a difference between a nominal position and a measured position for each particle-optical column for a plurality of test positions, wherein the plurality of test positions span a range of positions sampling a desired range of motion of the target stage, and determining a deviation of an actual position of each fiducial from a respective nominal position of each fiducial; generating a position error map for said deviations between said test location locations based on said deviations so determined, said position error map representing position deviations as a function of the position of a nominal origin; is preferred. (Mode 10) In the method of mode 9, During a writing process involving exposure of the target in the charged particle multi-beam processing apparatus, measurement results of positions of reference measurement points are applied to a position of the particle optical column used for correcting the position of a beam image generated on the target by the particle optical column, and the position of the column is adjusted using the position error map. is preferred. (Mode 11) In any of the methods of modes 1 to 10, measuring the current position of the target is performed only for the at least two predetermined reference measurement points corresponding to respective origins of particle-optical columns, these particle-optical columns being referred to as reference columns; and, Measuring the current position of the target includes: determining actual positions of said reference columns; calculating a position deviance of the entire charged particle beam array using the actual positions of the reference columns, wherein the position deviance includes an azimuthal and position offset; and correcting the effect of the misalignment on the charged particle beam array by repositioning the beam of each of the plurality of particle optical columns with a position correction appropriate to compensate for the misalignment applied to the respective origin of each particle optical column. Including is preferred. (Mode 12) In any of the methods of modes 1 to 11, The at least two predetermined reference measurement points are cross points having extrema of coordinates used in the distance measurement system. is preferred. (Mode 13) In any of the methods of modes 1 to 12, Measuring the current position of the target and, if applicable, calculating a beam displacement for the beam that compensates for deviation of the current target position from a nominal position is performed during a writing process performed on a substrate positioned at the position of the target. is preferred. (Mode 14) In the method of mode 13, Measuring the current position of the target and, if applicable, calculating the beam displacement is performed within a total time not exceeding a predetermined delay time, which is preferably 10 μs. is preferred. (Mode 15) In any of the methods of modes 1 to 14, The method comprises, for each position in the sequence of target motion positions, referred to as the current target position, performing the following steps: (i) positioning the target toward the current target position using a mechanical target stage system, thereby achieving an initial target position that is close (approximate) to the current target position; (ii) measuring the initial target position at a position corresponding to the reference measurement point to obtain initial target position coordinates; (iii) calculating the target offset using the initial target position coordinates and the coordinates of the reference measurement point, wherein the target offset includes a lateral displacement of the target at the initial target position relative to the current target position and a stage azimuth angle; (iv) calculating, for each particle-optical column and its respective beam, beam displacements and orientation corrections that compensate for differences between the initial target position for the current target position and the calculated stage azimuth angle for the position of the origin of each particle-optical column; and (v) applying to each beam a correction for the position and orientation of each beam image on the target according to the respective beam displacement and orientation corrections; Further comprising is preferred. (Mode 16) In any of the methods of modes 1 to 15, The reference measurement points are each located within a geometric projection of a pattern sub-image on the measurement surface and / or coincide with the position of a reference point of a corresponding particle-optical column. is preferred. (Mode 17) In any of the methods of modes 1 to 16, the distance measurement system includes an interferometer system using two sets of interferometer beams propagating in the measurement plane, each set having at least two interferometer beams used to perform position measurements along respective beam directions specific to each set; the beam directions of the two sets are different from each other; The geometric extensions of the different sets of interferometer beams intersect at crossing points, and at least two of the crossing points are used as reference measurement points for calculating the actual position and orientation of the target. is preferred. (Mode 18) In any of the methods of modes 1 to 17, the particle-optical columns are arranged in the charged particle beam array and with respect to each fiducial point according to a predetermined array, the particle-optical columns form at least two rows within the predetermined array extending parallel to a main direction of motion of the target, and the at least two rows are spaced apart from each other by a row offset measured in a direction perpendicular to the main direction. is preferred.

[0010] The above problems are solved by the method set forth in the appended claims. In particular, according to one aspect of the present invention, a method for controlling the positioning (mainly relative positioning) of a movable target and a charged particle beam array, wherein the charged particle beam array comprises a plurality of charged particle beams generated by a plurality of particle optical columns in a charged particle multi-beam processing device for target exposure, is proposed, in which the target is moved in a target plane through a predetermined sequence of target movement positions using a target stage of the charged particle multi-beam processing device, the plurality of particle optical columns are arranged along respective longitudinal axes (preferably parallel to each other) traversing the target plane at respective base points (usually different from each other), each particle optical column is configured to generate a respective charged particle beam and project the generated charged particle beam onto the target in a respective region around the respective base point to generate a pattern sub-image in said region according to a pattern to be exposed on the target, the method comprising: providing a charged particle multi-beam processing apparatus including a plurality of particle optical columns; Providing distance measurement systems (ranging systems); and Measuring the (precise or precise) current position of the target using a distance measurement system, after which repositioning of the charged particle beam of the particle-optical column can be performed based on the current position of the target. Including, the distance measurement system is configured to measure positions of at least two predetermined reference measurement points of the target within the target stage within a measurement plane, which may be the same as (i.e., coincident with) the target plane or a plane (substantially) parallel to the target plane; The measurement of the position of the reference measurement point is used to calculate the actual position and orientation of the target.

[0011] Advantageously, these results are then used to derive a target deviance representing the deviation of the actual target position and orientation from its associated nominal target motion position and orientation. Advantageously, this also enables repositioning of the charged particle beams of the particle optical columns based on the current position of the target by controlling the target stage to move to a corrected position to compensate for the target deviance and / or by calculating beam displacements for the particle optical columns in the charged particle beam array, each beam displacement representing a position correction applied to a respective fiducial point of the respective particle optical column to compensate for the target deviance.

[0012] The distance measurement system may be any suitable arrangement or device capable of providing a measurement of the position of a predetermined reference measurement point on a target with sufficient accuracy. In a preferred embodiment of the distance measurement system, an interferometer system is provided that uses (at least) two sets of interferometer beams propagating in an interferometer system plane parallel to the target surface, each set having at least two interferometer beams oriented along respective beam directions specific to each set (in the interferometer system plane), the beam directions of these sets being different from each other; The geometric extensions of the different sets of interferometer beams intersect at crossing points, at least two of which are within the geometric projection of the pattern sub-image onto the interferometer system plane (i.e., projected along the longitudinal direction of the charged particle beam) and are used as reference crossing points for calculating the position and orientation of the target.

[0013] The method preferably also includes calculating a target deviance, where the "target deviance" represents a deviation of the calculated position and orientation of the target from its associated nominal target motion position and orientation, and calculating, for at least one of the particle-optical columns, a deviation amount of the location of the fiducial of the respective particle-optical column corresponding to the target deviance applied to the location of the fiducial, and a beam displacement for the beam of the respective particle-optical column that compensates for the respective deviation amount.

[0014] This technical solution provides highly accurate measurements of the current position of the target and of the relative position of the particle-optical column with respect to the current (temporary) target position. Furthermore, the proposed method has the advantage that various position measurement operations can be performed in real time (i.e., during the writing process, without interfering with the strict time constraints of such writing process) and that position corrections are achieved by a separate beam deflector system, thus ensuring (guaranteeing) extremely high accuracy corrections compared to the lower accuracy of target stage positioning or other mechanical positioning approaches. Throughout this disclosure, when rotation of the particle-optical column of a target and / or column array is mentioned, this relates to the angle of rotation around an axis perpendicular to the target plane, also referred to as the azimuth angle. Similarly, the term target orientation should be understood as relating to the azimuth angle of the target.

[0015] In another advantageous aspect of the invention, position measurement and control is performed for each position in a sequence of target motion positions. For each such position, called current target position, this aspect proposes the following steps: (i) positioning the target towards the current target position using a mechanical target stage system, thereby achieving an initial target position that is close (approximate) to the current target position (due to the limited positioning accuracy of the target stage system); (ii) measuring an initial target position at a location (such as a cross point of the interferometer beams) corresponding to a reference measurement point (e.g., a reference cross point in the case of an interferometer system) to obtain initial target position coordinates; (iii) calculating the lateral displacement of the target and the stage azimuth angle at the initial target position relative to the current target position using the initial target position coordinates and the coordinates of the reference measurement point (or reference cross point, if applicable); (iv) calculating, for each particle-optical column and its respective beam, beam displacements and orientation corrections that compensate for differences between the initial target position for the current target position and the calculated stage azimuth angle for the position of the origin of each particle-optical column; and (v) applying to each beam a correction of the position and orientation of the image of each beam on the target according to the respective beam displacement and orientation correction; this can preferably be achieved by a deflection system arranged in the particle-optical column of each beam.

[0016] It is often advantageous to have the reference cross points at locations that respectively coincide with the positions of the origin points of the corresponding particle-optical columns, or at least lie within the geometric projection of the particle-optical columns onto the measurement plane (e.g., using a projection of a representative cross section or "shadow" projection of the particle-optical columns). Typically, the number of particle-optical columns, and therefore the number of origin points, is greater than the number of reference cross points. Therefore, it is often appropriate to select origin points as reference cross points that are arranged at a large distance from each other.

[0017] Furthermore, in many embodiments, in order to reduce the amount of calculations, it is advantageous to provide that the measurement of the current position of the target is performed only for at least two predetermined reference measurement points (typically corresponding to the respective origins of the particle-optical column). Preferably, these two (or more) predetermined reference measurement points may be cross points with extremal values ​​of the coordinates used in the distance measurement system. Such a measurement method may preferably comprise the following steps: Determining actual positions of reference columns (i.e., particle-optical columns corresponding to predetermined reference measurement points); calculating a position deviance of the entire charged particle beam array using the actual positions of the reference columns, the position deviance including azimuthal and position offsets; and Correcting the effect of misalignment on the charged particle beam array by repositioning (relocating) the beam of each of the plurality of particle optical columns with position corrections appropriate to compensate for the misalignment applied to the respective base points of each particle optical column.

[0018] Another aspect of the present invention addresses the reality that the actual positions of the particle-optical columns may deviate slightly but significantly from their nominal positions in the respective arrays, and that positioning movements of the target stage system often result in small variations in the target position that can cause inaccurate measurements by the interferometer system. Therefore, in many embodiments, it is advantageous to calculate the beam displacements taking into account the actual positions of the origins of the particle-optical columns within the charged particle beam array, whereby for each particle-optical column, the respective beam displacements are calculated from the lateral displacements determined at the reference measurement points (or, if applicable, the reference crossing points). This calculation can be performed, for example, by interpolating the lateral displacements or the respective deviations relative to the actual positions of the particle-optical column origins within the charged particle beam array. The positions of the origins of the particle-optical columns can be determined, for example, by an initial calibration process (e.g., with respect to steps i-v of the above method, preferably before step iv). In this initial calibration process: a test substrate is exposed by a writing process in which the particle-optical columns each write a test pattern on the test substrate; the test patterns can be, for example, copies of a (predetermined) template pattern, the template pattern including a pattern figure, such as a cross or a star, having multiple components arranged radially around a central location; so that in the resulting test pattern, the copies of the template pattern are arranged in an array corresponding to the array of the particle-optical columns; The position of the test pattern is measured (any suitable placement measurement tool in the art may be utilized for this purpose); The positions so measured are compared with the nominal positions of the respective particle-optical columns and the deviations from the nominal positions are stored. The positions determined by this approach can then be used to correct for individual deviations of the columns, for example by using the respective deflection systems mentioned above, whereas azimuthal corrections are usually assumed to be constant for all beams.

[0019] In a further preferred aspect of determining the actual positions of the particle-optical columns (i.e., their fiducials), it is proposed that for each particle-optical column, the deviation of the actual position of each fiducial (within the charged particle beam array) from its respective nominal position is determined by measuring the difference between the nominal position and the measurement position for each particle-optical column for a plurality of test positions, the plurality of test positions spanning a position range sampling a desired range of motion of the target stage, from which the deviation of the actual position of each fiducial from its respective nominal position can be determined. Then, based on the deviations thus determined, a position error map is generated using a predetermined interpolation method for the deviations between the locations of the test positions; this position error map represents the deviation of the position (particularly of the particle-optical column) as a function of the position of the nominal fiducial. In many embodiments, the application of this correction can be particularly advantageously performed "in real time," i.e., during a writing process involving exposure of a target in a multi-beam processing device. More specifically, the measurement results of the positions of the reference measurement points can be applied (in "real time") to the position of the particle-optical column, which is used to correct the position of the beam image generated by the particle-optical column on the target. In this case, the position of the column (or the locations of its corresponding fiducial points) is adjusted "in real time" using a position error map. In the special case of using an interferometer system with measurements of positions at (reference) cross points, the position of the column (or fiducial points) is adjusted "in real time" using a position error map for the nominal position of the column (or its fiducial points) derived from the positions at the respective cross points and the associated position corrections. In particular, if the position (or location) of a (reference) cross point lies within the geometric projection of the particle-optical column onto the measurement plane, it may be advantageous to use the data of this cross point (in particular the correction derived from the position error map of this cross point) for correcting the position of the column (or its fiducial points).

[0020] In many embodiments, the particle-optical columns are arranged within the charged particle beam array and for each base point according to a predetermined array (which is often a regular array), and within the predetermined array the particle-optical columns form at least two rows (or columns) extending parallel to the main direction of movement of the target along the series of target movement points, and the rows are spaced apart from each other by a row offset measured in a direction perpendicular to this main direction.

[0021] According to a particular aspect of the invention, the operations of measuring the (highly accurate) current position of the target and, if applicable, calculating a beam displacement for the beam to compensate for deviations of the current target position from a nominal position, can be performed in "real time", i.e., during a writing process being performed on a substrate positioned at the target's location. The operations of measuring the current target position and, if applicable, calculating a beam displacement can be advantageously performed within a total time not exceeding a predetermined delay time, which delay time is preferably 10 μs.

[0022] In many embodiments of the present invention, processing circuitry may be used that includes one or more field programmable gate arrays (FPGAs) for performing or controlling the steps of measuring the current position of the target and, optionally, for further calculations based thereon.

[0023] Many embodiments of the present invention include a fine position adjustment method that helps correct or compensate for systematic errors in the distance measurement system. This method advantageously includes: obtaining a position error map, the position error map representing position errors in the distance measurement system as a function of respective positions; obtaining distance measurements along a plurality of coordinate values ​​from a distance measurement system; correcting the distance measurements using the position error map to obtain adjusted distance measurements; and Using the adjusted distance measurements to determine center data, including the center position and azimuth angle of the target stage or target. Including, Further, optionally, transmitting the centroid data to a stage control unit for correction of the position of the target stage or target.

[0024] The position refinement method may further provide that the step of obtaining distance measurements along a plurality of coordinate values ​​is performed only for a plurality of predetermined crossing points, the crossing points having extremal values ​​of the coordinate(s) in the distance measurement system.

[0025] To determine the position error map used in the position refinement method, the following steps may be suitable: performing an exposure on a test substrate with a calibration pattern including an array of alignment markers and processing the test substrate; Determining the location of an alignment marker; Obtaining positional displacements of the alignment markers relative to their respective nominal positions; and generating a position error map from said position displacements; Here, a preferred embodiment of the step of performing exposure on the test substrate (when an array of particle optical columns is used, each column having a pattern definition device for defining a pattern portion image to be written on the target) is that for the exposure of the alignment markers only a center portion of the pattern definition device is used, which has the advantage that the center region of the pattern definition device is generally associated with minimal imaging errors.

[0026] In the following, exemplary and non-limiting embodiments are described which are diagrammatically illustrated in the drawings in order to further explain the invention. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a longitudinal cross-sectional view of an example of a suitable multi-column writer tool including a distance measurement system and associated control unit. [Figure 2] 1 is an example of a sub-column array according to a regular rectangular array. [Figure 3] 10 is another example of a sub-column array according to a regular staggered array. [Figure 4] 1 is an example flowchart of operations performed by a control unit of a distance measurement system. [Figure 5] 3 shows an example of a layout of interferometer system reference crossing points for a distance measurement system with the sub-column array of FIG. 2. [Figure 6] 4 is another example of a layout of interferometer system reference crossing points of a distance measurement system for the sub-column array of FIG. 3. [Figure 7] 1 shows an example of a target in an exemplary general location and various relevant parameters of a distance measurement system. [Figure 8] An example of a test substrate used for the calibration method to determine the exact position of the sub-column origins relative to the measurements of the interferometer system. [Figure 9] 1 is an example flowchart illustrating the processing of various types of location-related data. [Figure 10] FIG. 1 is a cross-sectional view of an example of a multipole electrode having eight sector electrodes. [Figure 11] Detail of the gap between the two sector electrodes of the multipole electrode of Figure 10. [Figure 12] FIG. 10 is a perspective view of a variation of a multipole electrode having four sector electrodes. [Figure 13] 7 is an example of an exemplary interferometer system related to the layout of Figure 6, shown in its entirety in plan view. [Figure 14a]7 is an example of an exemplary interferometer system for the layout of Figure 6. One interferometer head is shown looking along the Z axis. [Figure 14b] 7 is an example of an exemplary interferometer system for the layout of Figure 6. One interferometer head is shown looking along the X axis. [Figure 14c] 7 is an example of an exemplary interferometer system for the layout of Figure 6. One interferometer head is shown looking along the Y axis. [Example]

[0028] The detailed description of exemplary embodiments of the present invention provided below discloses the basic idea, implementation, and further advantageous developments of the present invention. It should be clear to those skilled in the art to freely combine some or all of the embodiments described herein as deemed suitable for a particular application of the present invention. Throughout this disclosure, terms such as "advantageous," "exemplary," "typical," or "preferred" indicate elements or dimensions that are particularly suitable (but not essential) for the present invention or an embodiment thereof, but may be modified, if deemed appropriate by those skilled in the art, unless clearly essential. It should be understood that the present invention is not limited to the exemplary embodiments described below, which are provided for illustrative purposes and merely provide preferred implementations of the present invention. Within the scope of this disclosure, terms relating to the vertical direction, such as "up" or "down," should be understood to refer to the direction of the particle beam propagating within each particle-optical column, extending downward ("vertically") along a longitudinal axis. This longitudinal axis is generally identical to the Z direction, with the X and Y directions being the transverse (horizontal) axes.

[0029] Lithography equipment

[0030] In general, the present invention is suitable for general multi-column charged particle exposure tools, such as an array of variably shaped beam or Gaussian beam systems. Many preferred embodiments of the present invention are embodied in a multi-column, multi-beam charged particle tool, such as the multi-column writer tool shown in schematic cross-section in Figure 1. Writer tools use charged particle beams formed from charged particles, which can be electrons or ions (e.g., positively charged ions).

[0031] The writer tool 101 includes a vacuum housing 110 for a multi-column charged particle optics 102, a target chamber 103 to which the multi-column charged particle optics is mounted by a column base plate 104. Within the target chamber 103 is an XY stage 105, e.g., an air-bearing vacuum stage controlled by a distance measurement system 121 and corresponding control unit 120, to which a substrate chuck 106, preferably an electrostatic chuck, is mounted using a suitable manipulation system. The chuck 106 holds a substrate 107 that serves as a target, such as a silicon wafer or photomask with an electron or ion beam sensitive resist layer.

[0032] The multi-column optical system 102 includes a number of sub-columns 109 (the number of columns shown is reduced for better clarity, but may represent a much larger number of columns present in some embodiment multi-column devices). The sub-columns 109 preferably have the same configuration and are positioned side-by-side with their axes parallel to one another. Each sub-column comprises an illumination system 111, including an electron or ion source 111a, an extraction system 111b, and an electrostatic multi-electrode condenser optics 111c, which delivers a wide, telecentric charged particle beam to a pattern definition (PD) system 112, adapted to pass only through a number of apertures that define the shapes of the sub-beams ("beamlets") transmitted through the apertures (beam shapers), and a charged particle reduction projection optics 116, consisting of a number of sequentially arranged electro-magneto-optical projector stages, preferably including electrostatic and / or magnetic lenses, and possibly other particle-optical devices. In the embodiment shown in Figure 1, the projection optics 116 includes a first lens 113, e.g., an accelerating electrostatic multi-electrode lens, while a second lens 114, arranged downstream of the first lens, is realized using an electromagnetic lens.

[0033] In each subcolumn 109, a first lens 113 of the projection optics forms a first crossover of the particle beam, while a second lens 114 forms a second crossover. In the second lens, a beam aperture 115 is configured to filter out beam portions that deviate from their respective optical axes due to deflection in the PD system. Each second lens 114 of the subcolumns may be attached to a reference plate 117, which is preferably attached to the column base plate 104 by suitable fastening means 118. Attached to the reference plate 117 is a portion 119 of the off-axis optical alignment system. To position and shape the beam as it traverses the column, each subcolumn includes a multipole electrode system usable in conjunction with the projection optics. The writing multipole 122 serves, among other functions, to position the patterned beams of each subcolumn relative to each other and to the stage 105.

[0034] 10, 11, and 12 show preferred exemplary embodiments of multipole electrodes in a multipole electrode system, particularly in the drawing multipole 122. Each multipole electrode is composed of three or more metal ring sector components, hereinafter also referred to as rods, that serve as electrodes (sub-electrodes) of the multipole electrode. Preferably, the rods have the same geometric shape. A cross-sectional view of an example of a multipole electrode 511 with eight rods (sector electrodes) 508 is shown in FIG. 10; FIG. 11 shows an enlarged detail of the gap between two rods. FIG. 12 shows a variant of a multipole electrode 540 with four sector electrodes 544. The preferred number of rods in a multipole electrode is 4, 6, 8, 12, or 16, depending on the desired effect to be achieved.

[0035] Referring to FIG. 10 , rods 508 are disposed within an enclosing sleeve that serves as support 501. The rods 508 can be individually applied with an electric potential by respective external power supply units. Additionally, a global offset voltage can be applied to cause them to behave as additive electrostatic lenses. By applying different voltages to the individual rods 508, various electric field configurations, such as dipole, quadrupole, or higher-order electrostatic fields, can be realized for the purpose of shaping the particle beam that crosses each corresponding transversal section of the optical axis 503. For typical applications, the voltages applied to the rods 508 are typically on the order of up to several tens of volts. Such beam shaping can be used to compensate for errors due to imperfections in the optical system, such as magnetic inhomogeneities, mechanical manufacturing, and / or assembly accuracy. In this regard, when a multipole is used as a dipole, whose orientation(s) in the plane defined by the X and Y axes can be arbitrary, the beam position relative to the optical axis 503 can be corrected if at least four different voltages are applied to the rods: +V1 (diagonally hatched rods on the right side of the page), +V2 (cross-hatched rods on the top side of the page), −V1 (diagonally hatched rods on the left side of the page), and −V2 (cross-hatched rods on the bottom side of the page). Additionally, astigmatism or other higher-order distortions due to the multipole, when the latter is used as a quadrupole or higher-order multipole, can be compensated for by applying appropriate voltages to the individual rods in a similar manner to the dipole case. The gap 505 between the sector electrodes forming the rod 508 is advantageously angled (bent) (or zigzagged, a "labyrinth") so that particles 504 that deviate from the beam propagating in the central space within the multipole electrode travel outside the multipole electrode and may possibly (adversely) affect the support 501 or other external components, but avoid colliding with the surface of the rod.Outside the rods 508, the gaps 505 terminate in pouches that serve to collect particles and drain their charge to a drain electrode (not shown), which helps to avoid charge build-up and associated stray electric fields that may affect the charged particle beam propagating through the multipole electrodes 511.

[0036] The reference plate is manufactured from a suitable base material with a low coefficient of thermal expansion, such as a ceramic material based on silicon oxide or aluminum oxide, which has the advantages of light weight, high modulus of elasticity and high thermal conductivity, and which can be suitably covered, at least in its relevant parts, with a conductive coating to prevent charging (by allowing static charge to be discharged).

[0037] The PD system 112 of each subcolumn serves to form from the particle beam a number of so-called beamlets containing information of the pattern to be transferred to the target. The structure, operation and data processing of the PD system are disclosed in the applicant's US 9,443,699 and US 9,495,499.

[0038] Multi-Column Architecture

[0039] An example of an exemplary sub-column array with corresponding column exposure fields suitable for the present invention is shown in FIGS.

[0040] 2 shows an example of a rectangular layout with column exposure fields limited in the X and Y directions. Sub-columns 21 containing corresponding patterned beams 22 (the size of which is exaggerated for clarity and is generally smaller than shown) have respective pitches DX and DY and are arranged in a regular grid spanning the entire exposure area 20 (the portion of the substrate to be exposed). The exposure area is divided into column exposure fields 23 (indicated by different hatching patterns). In this embodiment of the invention, the size of the column exposure fields is matched to the sub-column pitch, i.e., beam 22 of each sub-column 21 exposes a single column exposure field 23.

[0041] 3 shows another example of a column array layout, in which sub-columns 25 containing corresponding patterned beams 26 are arranged in a staggered grid with pitches DX and DY and an offset DY / 2 between the first and second columns. The column exposure fields are limited only in the Y direction and form stripes 27 across the exposure area 24; these stripes 27 correspond to the column exposure fields 23 of FIG. 2.

[0042] In array variations, the column exposure fields are spaced apart between the sub-columns. The subcolumns may overlap in a regular or irregular manner to allow for smooth transitions in the beam, compensation for misplaced subcolumns, or blending of subcolumn aberrations.

[0043] Other array layouts may provide variations and / or combinations of the above two exemplary embodiments, for example by combining the column layout of FIG. 2 with the column exposure fields of FIG.

[0044] Stage and beam position measurement and control

[0045] The XY stage 105 serves to ensure proper continuous positioning of the target, typically involving constant motion of the substrate relative to the sub-column beam. Furthermore, the stage 105 is advantageously configured to compensate for undesired vibrations, forces, or torques, e.g., caused by imperfections in the stage's manufacturing or disturbances. It should be noted that not only the substrate's position but also its orientation—in particular its yaw, which can change as the stage traverses its range of motion—is crucial for sufficiently accurate exposure results. Here, the term "yaw" refers to rotation about an axis perpendicular to the target surface. To monitor the stage's position and orientation, and thus the relative position of the sub-column array 19 and the substrate 107, a distance measurement system 121 is used, which may be based, for example, on multiple laser interferometers as shown in this embodiment. To ensure minimal deviations from the desired position, a control unit 120 is provided that uses one or more controllers forming a control loop for the distance measurement and stage control system.

[0046] FIG. 4 is an exemplary flowchart illustrating one example of data processing performed in the control unit 120 and its control loop. The distance measurement system 121 stores X and / or Y stage positions for multiple positions and orientations. The measured positions are provided to a suitable processing unit 124, e.g., a processing circuit including a microcontroller and / or one or more field-programmable gate arrays (FPGAs), where the position data is processed with appropriate low-pass filters, stage-position-dependent fine position adjustments are applied, and the stage position and rotation state are calculated. The processed data is transmitted to the beam control unit 123 (also referred to as a writing control unit, WCU), which can adjust the position of the column beams (controlled by the writing multipole 122) and the stage 105 and perform appropriate repositioning of the beamlets to compensate for differences between the measured and desired positions. Additionally, the position data is provided to the stage control unit 125, which ensures that the stage moves to the desired position with minimal stage azimuth. The changed position is then stored by the distance measurement system 121, completing the control loop.

[0047] Distance measurement system 121 including multiple distance measurement devices according to the present invention is implemented using a commercially available laser interferometer system with a measurement accuracy of approximately 0.2 nm. The interferometers are positioned (located) at predetermined fixed reference points, for example inside vacuum chamber 103, and measure the distance in the X or Y direction relative to a plane mirror attached or coated on stage 105 or chuck 160.

[0048] Distance measurement system architecture

[0049] According to the present invention, the distance measurement devices (e.g., interferometer beams) of the distance measurement system 121 are arranged such that the lines (i.e., geometric extensions) of the beams in the X and Y directions (or generally along two of a plurality of different directions) form at least two crossing points (which also correspond to the reference measurement points of the present invention and are referred to as "interferometer crossings" or simply "crosses"). Preferably, the at least two interferometer crosses are positioned at or near the centers of the charged particle beams generated by the respective subcolumns, preferably towards or at opposite corners of the subcolumn array. Alignment of the interferometer crosses with the beam centers allows tracking of the positions of the respective beam centers independently of the stage orientation and subsequently allows generation of fine-tuning maps for the respective beams in a straightforward manner (see below for further details). Furthermore, it is advantageous to select the crosses so that they have a large distance in both axial directions, since this allows for azimuth measurements with a large lever. By selecting crosses that are at a maximum distance from each other, it is possible to achieve adequate precision (accuracy) of the position measurement and especially of the azimuth measurement. Figures 5 and 6 show examples of suitable interferometer arrangements for the embodiments of Figures 2 and 3.

[0050] 5 shows an example of an arrangement with distance measurement using three interferometer beams per direction, i.e., N=3 beams for coordinates X1, X2, X3 and M=3 beams for coordinates Y1, Y2, Y3, as one example among many possible implementations realizing an overdetermined arrangement. The interferometer beams impinge on the chuck 106 at a mounted or coated mirror surface 50. The (virtual) expanded beam trajectories form 3 × 3 = 9 intersections, each corresponding to a cross point (reference measurement point) located at the center of the corresponding sub-column beam 22. According to preferred embodiments of the invention, the cross points 51, 52 are positioned such that they encompass the sub-column positions at the corners of the array and have large, preferably maximum, axial offsets MX, MY, enabling extremely accurate determination of the stage orientation. Another exemplary arrangement with four interferometer beams (N=M=2) at X1, X2 and Y1, Y2 is shown in FIG.

[0051] According to the invention, the geometric extension (lines) of the interferometer beams form at least two cross points, which are located at or near the center of the sub-column beam 26. Preferably, the cross points are located relative to the sub-column positions such that they comprise opposite corners of the sub-column array, as shown by crosses 53 and 54 or crosses 55 and 56 in Figure 6. Advantageously, the crosses are selected such that they have a large or even maximum distance MX, MY in both axial directions, which is the case for the pair of crosses 55 and 56 in the embodiment shown in Figure 6.

[0052] 13 shows a typical, but illustrative, implementation of the interferometric distance measurement system 21. A laser head 130 generates a beam 131, which is split by a primary beam splitter 132 into sub-beams 133 and 134. A secondary beam splitter 135 further splits the sub-beams to feed a set of interferometer heads 136 and 137, which perform horizontal and vertical measurements (using measurement beam 139) of the distance relative to a mirror 50 fixed on a chuck 106. The interferometer system typically further includes additional elements such as a so-called beam bender 138 and / or a beam manipulator (not shown).

[0053] 14a to 14c, in a preferred embodiment of the present invention, at least one interferometer head 137 of the sets of interferometers performing horizontal and vertical measurements is a multi-axis interferometer head that serves to measure multiple vertical offsets 138 for determining stage pitch. FIGS. 14a to 14c show the interferometer head 137 as viewed along the Z, X, and Y axes of the system, respectively. The interferometer head 137 that measures the vertical distance is fixed to a mount 139, e.g., the same mount to which the stage is fixed. In a further preferred development of the present invention, the multi-axis interferometer may also preferably include at least four beams configured to additionally measure the distance and pitch of the column 109 by means of column mirrors 140 associated with the interferometer heads and to serve as interferometric reference beams for the sets of interferometer heads. This configuration has the advantage that only the relative motion between the column 109 and the chuck 106 is tracked. In a further embodiment, the interferometry system tracks (i.e., measures) the absolute positions of (at least) two columns, which can be used to determine positional deviations from a nominal position; such deviations may be caused, for example, by thermal deformation of the support structure of the array of columns. The positional deviations may typically include offset plus rotational deviations of the entire array of columns. In this embodiment, the positional deviations are corrected without individually measuring the position of each column within the array, in a manner similar to that for determining stage position and rotational errors; rather, the determination is based only on measurements of (at least) two selected columns whose positions serve as reference measurement points. The positional deviations thus determined can be corrected, for example, via repositioning the beams of the respective columns.

[0054] Distance measuring system and chuck coordinates

[0055] Below, an exemplary method is described to explain how the measurements of the distance measurement system 121 can be used to track positions for the chuck and / or mask.

[0056] 7 shows an example of a distance measurement system having a distance measurement coordinate system 72 represented by capital letters X and Y. Two beams 70 and 71 are arranged parallel to the X and Y axes, respectively, and are spaced apart by (0, Y D ) and (X D , 0) (the coordinates X, Y are appropriately defined to fit this particular definition of head position). D ,Y D The chuck 106 holding the mask substrate 107 is (X N ,Y N ) and rotated by an angle φ (which is typically on the order of μrad, but is shown exaggerated in FIG. 7 for illustrative purposes), to generate a chuck coordinate system 73 (denoted by lowercase x, y) with origin N. The mask substrate 107 (hereafter simply referred to as "substrate") has a further offset and rotation relative to the chuck 106, but this can be corrected or compensated for by methods that do not form part of this invention and will not be discussed here.

[0057] Coordinate X in the distance measurement coordinate system P , Y P For any point P with chuck coordinate x P , y P is a given distance measure (value) X K , Y K and the azimuth angle φ TIFF2025186168000007.tif22156 where: TIFF2025186168000008.tif26153 and TIFF2025186168000009.tif26153.

[0058] Small angle approximation TIFF2025186168000010.tif17153 Using TIFF2025186168000011.tif19153, the above formula is simplified to TIFF2025186168000012.tif35156 where TIFF2025186168000013.tif23153. In particular, the beam cross D in the chuck coordinate is TIFF2025186168000014.tif23156 Therefore, ignoring the constant offset, the position of the distance measurement beam cross (and aligned sub-columns) on the substrate can be tracked directly by the distance measurement devices, independent of substrate rotation. The offset can be determined, for example, by performing a calibration using known chuck coordinates on the beam control target.

[0059] Calculation of substrate orientation and subcolumn position

[0060] For distance measurement systems with at least two interferometer crosses, such as the embodiment shown in Figures 5 and 6, by averaging (2) over multiple beams, TIFF2025186168000015.tif38156 where TIFF2025186168000016.tif30153 is TIFF2025186168000017.tif18153 and are the coordinates (in the distance measurement coordinate system) of the center C (or 57) of the coordinate measurement system using M+N beams in TIFF2025186168000018.tif18153, TIFF2025186168000019.tif31153 is the corresponding average distance measurement. In particular, the chuck coordinate x of center C (denoted by 57 in FIGS. 5 and 6) C , y C: TIFF2025186168000020.tif25156 is given by a constant offset and independently of the azimuth angle φ TIFF2025186168000021.tif18153. This averages out the error contributions of the individual distance measurement devices, so equation (4) can be used to calculate the chuck position (or substrate position) of the sub-column array (including those not tracked by the distance measurement beam cross) by fitting a constant sub-column stage coordinate offset relative to the center of the distance measurement system into equation (4). TIFF2025186168000022.tif19153 and TIFF2025186168000023.tif17153. For this purpose, the sub-column stage coordinate offsets can be determined with sufficiently high accuracy, for example, by using a beam calibration target or by exposing a calibration pattern with each sub-column onto a calibration substrate and measuring the offset relative to the center using an offline metrology tool. The stage azimuth angle φ required in equation (4) can be calculated as follows: TIFF2025186168000024.tif39156 5 or 6. D1 -Y D2 In an overdetermined distance measurement arrangement such as that of FIG. 5, the azimuth angle can alternatively be determined by the slope in the measurement. can be determined by using all measurements in a linear least squares fit of TIFF2025186168000025.tif16153 TIFF2025186168000026.tif47156

[0061] Distance measurement and fine adjustment of column position

[0062] Due to imperfections in the mirror surface 50, the (e.g., interferometric) measurements of the distance measurement system may have systematic errors on the order of 100 nm, which may be problematic in terms of the desired accuracy required in high-precision lithography. To address this potential problem, a further aspect of the present invention is proposed that advantageously uses additional fine-tuning of the distance measurements, which may be based on position-error maps generated using calibration exposures. An example implementation of the fine-tuning of the position is described below with reference to FIG. 8 and primarily in light of the embodiment of FIG. 6, where exactly two distance measurement beam crosses 51 are aligned with corresponding sub-column centers 22.

[0063] Referring to Figure 8, the calibration method may be based on a test exposure on a substrate 87, which is provided with a calibration pattern including an array of registration markers 80 (e.g., in the shape of a cross in the illustrated example, although markers of other shapes can also be used) and exposed in a regular grid across an exposure area 85 on the substrate. In the case of a multi-column, multi-beam charged particle exposure apparatus, it may be preferable to use a central portion of the pattern definition device of each column to write the calibration pattern, for example by using a relatively small number of beamlets of the pattern definition device. This is preferred because the center of the pattern definition device typically exhibits the least amount of charged particle optical aberrations that can complicate calibration measurements. As already explained in relation to Figures 2 and 3, the exposure area is further divided into multiple column exposure fields 23, 27, which are indicated in Figure 8 by different types of hatching (corresponding to the layout of Figure 3), with each exposure field being exposed by a single sub-column. Once the calibration pattern has been exposed onto a substrate and the substrate has been processed (e.g., developed), the marker positions on the so-processed substrate are determined and then compared to nominal positions 81 on a regular grid using a prior art alignment metrology tool (e.g., ZEISS PROVE® 26ext). Position displacements 82 (shown exaggerated for clarity in FIG. 8 ) for each marker position are thus obtained, which comprise a displacement vector (from nominal position to effective position) for each position on the exposure area. The set of displacements 82 is then used to create a position correction map (in step 94 of FIG. 9 , see below). TIFF2025186168000027.tif16153, can be obtained by modeling or interpolating using a suitable interpolation approach such as bilinear, biquadratic, or spline interpolation. Note that in a further extension, the position correction map can also include an error component for possible misalignment of the sub-column positions 22 (relative to the nominal position of the interferometer cross 51 of the distance measurement system), which is typically constant across each sub-column exposure field but may vary from sub-column to sub-column. Often, the position correction maps in column exposure fields 83 and 84 associated with sub-columns at cross points used in an interferometer beam system (such as crosses 55 and 56 in FIG. 6 ) are particularly important because these exposure fields 83, 84 are exposed by sub-columns whose position is controlled by the cross of the distance measurement beams. Here, the position correction map represents errors in the interferometer system (e.g., due to poor mirror flatness) because each beam position is tracked directly, independent of the stage orientation. For the very first exposure of the calibration pattern, the position correction map can be initialized to a zero map, or an initial best guess (e.g., obtained from a previous registration determination exposure) is used and then updated with the registration measurements.

[0064] The processing of various types of position-related data is illustrated in the flow chart of Figure 9. The determination of displacement vectors and / or position correction maps occurs in step 94. The result of this step is the position correction map TIFF2025186168000028.tif17153 is used for distance measurements and estimated sub-column position correction. Distance measurement system 121 calculates the raw measurements for its M+N beams. TIFF2025186168000029.tif16153 and TIFF2025186168000030.tif16153. Advantageously, these raw measurements may be low-pass filtered by a filtering sub-unit 91, which is preferably provided as an (optional) component of the processing unit 124 of the control unit 120, to provide the filtered distance measurements. Generates TIFF2025186168000031.tif16153.

[0065] Next, in the distance measurement refinement subunit 92 of the processing unit 124, the preferably filtered distance measurement TIFF2025186168000032.tif16153 is a position correction map for a column exposure field including sub-columns (e.g., sub-columns 55, 56 in the embodiment of FIG. 6) controlled by each measurement. This step is performed by calculating the subcolumn coordinates using equation (3) for each distance measurement beam cross that is aligned with a subcolumn (which is independent of the stage orientation due to the small angle approximation), and subtracting the correction value given by the position correction map in the obtained coordinates from the measurements for the cross beams, resulting in adjusted distance measurements. TIFF2025186168000034.tif16153 and TIFF2025186168000035.tif17153 is obtained. In the embodiment of FIG. 6, for example, for k=1, 2, TIFF2025186168000036.tif15153 The resulting file is TIFF2025186168000037.tif17153.

[0066] If multiple distance measurement beam crosses are aligned with the sub-columns for a single beam, the adjustments can be averaged accordingly. So, for example, in the embodiment of FIG. Regarding TIFF2025186168000038.tif16153, TIFF2025186168000039.tif27153 The resulting file is TIFF2025186168000040.tif22153.

[0067] Still referring to FIG. 9, the adjusted distance measurement TIFF2025186168000041.tif16153 Using TIFF2025186168000042.tif17153, the column position and orientation calculation subunit 93 of the processing unit 124 calculates the position of the distance measurement system center on the chuck and / or substrate. TIFF2025186168000043.tif16153 and its rotation φ relative to the distance measurement system are determined using, for example, equations (5) and (6), and these data (i.e., position TIFF2025186168000044.tif17153 and rotation φ) to the stage control unit 125. Note that, in general, adjustments of the preceding steps have a significant effect on the determined stage position and azimuth angle. Additionally, the sub-column position on the chuck (or substrate) TIFF2025186168000045.tif18153 and TIFF2025186168000046.tif19153 can be determined. For the subcolumns controlled by the distance measurement beam cross (i.e., the subcolumns at the reference measurement points of the distance measurement system, such as subcolumns 55 and 56 in the embodiment of FIG. 6), the coordinates are determined by equation (3), while for other subcolumns (such as subcolumns 53, 54, 58, and 59 in FIG. 6), equation (4) can be used as described above.

[0068] The sub-column positions calculated in the above manner are then transmitted to the beam control unit 123. Using these calculated positions and the predetermined nominal positions of the sub-columns, the beam control unit applies corrections to the sub-column beams such that the beam images produced on the substrate are shifted from their calculated positions on the substrate to the desired nominal positions. This is done using the individual deflection systems of the sub-columns, for example by applying / adjusting control voltages to the respective writing multipoles 122.

[0069] All or part of the above embodiments and examples can be described as the following supplementary notes, but are not limited thereto. [Appendix 1] A method for controlling the relative positioning of a moving target and a charged particle beam array. the charged particle beam array includes a plurality of charged particle beams generated by a plurality of particle optical columns in a charged particle multi-beam processing apparatus for exposure of a target; the target is moved through a predetermined series of target movement positions within a target plane using a target stage of the charged particle multi-beam processing apparatus; The plurality of particle optical columns are arranged along respective longitudinal axes that intersect (pass through) the target surface at respective base points, and each particle optical column is configured to generate a respective charged particle beam and project the generated charged particle beam onto the target in a respective region around the respective base point to generate a pattern subimage in that region according to a pattern to be exposed on the target. The method comprises: providing the charged particle multi-beam processing apparatus including the plurality of particle optical columns; Providing distance measurement systems (ranging systems); and measuring the current position of the target using the distance measurement system; performing repositioning of the charged particle beam of the particle optical column based on the current position of the target; Including, The distance measurement system is configured to measure the positions of at least two predetermined reference measurement points of the target within the target stage in a measurement plane that is coincident with or substantially parallel to the target plane. The measurement results of the position of the reference measurement point are used to calculate the actual position and orientation of the target and to derive a target deviance representing the deviation of the actual target position and orientation from its associated nominal target motion position and orientation. performing repositioning of the charged particle beam of the particle optical column based on the current position of the target, controlling the target stage to move to a corrected position to compensate for the target misalignment; and calculating beam displacements for the particle optical columns within the charged particle beam array, each of the beam displacements representing a position correction for a position of a respective fiducial point of a respective particle optical column that compensates for a target shift applied to the respective fiducial point; It includes at least one of the following. [Appendix 2] In the method of Appendix 1, The method further includes a fine position adjustment method for a systematic error of the distance measurement system; The fine position adjustment method includes: obtaining a position error map, wherein the position error map represents position errors in the distance measurement system as a function of respective positions; distance measurements along a plurality of coordinate values ​​from the distance measurement system; To get TIFF2025186168000047.tif16153, Correcting the distance measurements using the position error map to obtain adjusted distance measurements Obtain TIFF2025186168000048.tif17153, and The adjusted distance measurements are used to determine the center position of the target stage or target. TIFF2025186168000049.tif16153 and azimuth angle Determine the center data, including TIFF2025186168000050.tif16153 Includes. [Appendix 3] In the above method, especially in the method of Appendix 2, The fine position adjustment method includes: transmitting the center data to a stage control unit for correction of the position of the target stage or target. Further includes: [Appendix 4] In the above method, particularly in the method of appendix 2 or 3, Distance measurements along multiple coordinate values The step of obtaining TIFF2025186168000051.tif16153 is performed only for a plurality of predetermined crossing points, said crossing points having extremal values ​​of coordinates in said distance measurement system. [Appendix 5] In the above method, particularly in any of the methods of Appendices 2 to 4, The position error map used in the fine position adjustment method is performing an exposure on a test substrate with a calibration pattern including an array of alignment markers and processing the test substrate; determining the position of the alignment marker; obtaining positional displacements of the alignment markers relative to their respective nominal positions; and generating a position error map from said position displacements; is determined by. [Appendix 6] In the above method, particularly in the method of Appendix 5, in the step of performing exposure on a test substrate, exposure of said alignment markers is performed using said particle optical columns, wherein each particle optical column uses its pattern definition device to define a pattern sub-image that depicts its alignment marker; Only a center portion of the pattern definition device is used for exposure of the alignment markers. [Appendix 7] In the above method, particularly in any of the methods of Appendices 1 to 6, The position of the origin of the particle-optical column is determined using an initial calibration process; In the initial calibration process, a test substrate is exposed by a writing process in which each of the particle optical columns writes a test pattern onto the test substrate; The position of the test pattern is measured; The positions so measured are compared with the nominal positions of the respective particle-optical columns and the deviations from the nominal positions are stored. [Appendix 8] In the above method, particularly in the method of Appendix 7, The test patterns are copies of a template pattern, which includes a pattern shape, such as a cross or star location, having multiple components arranged radially around a central location. [Appendix 9] In the above method, particularly in any of the methods of Appendices 1 to 8, calculating the beam displacement includes, for each particle-optical column, measuring a difference between a nominal position and a measured position for each particle-optical column for a plurality of test positions, the plurality of test positions spanning a position range sampling a desired range of motion of the target stage, and determining a deviation of an actual position of each fiducial from a respective nominal position of each fiducial; Based on the offsets so determined, a position error map is generated for the offsets between locations of the test position, the position error map representing the position offset as a function of the position of the nominal fiducial. [Appendix 10] In the above method, particularly in the method of Appendix 9, During execution of a drawing process involving exposure of the target in the charged particle multi-beam processing apparatus, measurement results of the positions of reference measurement points are applied to the position of the particle optical column used to correct the position of the beam image generated on the target by the particle optical column, and the position of the column is adjusted using the position error map. [Appendix 11] In the above method, particularly in any of the methods of Appendices 1 to 10, measuring the current position of the target is performed only for the at least two predetermined reference measurement points corresponding to respective origins of particle-optical columns, these particle-optical columns being referred to as reference columns; and, Measuring the current position of the target includes: determining actual positions of said reference columns; calculating a position deviance of the entire charged particle beam array using the actual positions of the reference columns, wherein the position deviance includes an azimuthal and position offset; and correcting the effect of the misalignment on the charged particle beam array by repositioning the beam of each of the plurality of particle optical columns with a position correction appropriate to compensate for the misalignment applied to the respective origin of each particle optical column. Includes. [Appendix 12] In the above method, particularly in any of the methods of Appendices 1 to 11, The at least two predetermined reference measurement points are cross points having extrema of coordinates used in the distance measurement system. [Appendix 13] In the above method, particularly in any of the methods of Appendices 1 to 12, Measuring the current position of the target and, if applicable, calculating a beam displacement for the beam that compensates for the deviation of the current target position from a nominal position is performed during a writing process performed on a substrate positioned at the location (or portion) of the target. [Appendix 14] In the above method, particularly in the method of Appendix 13, Measuring the current position of the target and, if applicable, calculating the beam displacement is performed within a total time not exceeding a predetermined delay time, which is preferably 10 μs. [Appendix 15] In the above method, particularly in any of the methods of Appendices 1 to 14, The method comprises, for each position in the sequence of target motion positions, referred to as the current target position, performing the following steps: (i) positioning the target toward the current target position using a mechanical target stage system, thereby achieving an initial target position that is close (approximate) to the current target position; (ii) measuring the initial target position at a position corresponding to the reference measurement point to obtain initial target position coordinates; (iii) calculating the target offset using the initial target position coordinates and the coordinates of the reference measurement point, wherein the target offset includes a lateral displacement of the target at the initial target position relative to the current target position and a stage azimuth angle; (iv) calculating, for each particle-optical column and its respective beam, beam displacements and orientation corrections that compensate for differences between the initial target position for the current target position and the calculated stage azimuth angle for the position of the origin of each particle-optical column; and (v) applying to each beam a correction for the position and orientation of each beam image on the target according to the respective beam displacement and orientation corrections; Further includes: [Appendix 16] In the above method, particularly in any of the methods of Appendices 1 to 15, The reference measurement points are each located within a geometric projection of a pattern sub-image on the measurement surface and / or correspond to the position of a corresponding origin of a particle-optical column. [Appendix 17] In the above method, particularly in any of the methods of Appendices 1 to 16, the distance measurement system includes an interferometer system using two sets of interferometer beams propagating in the measurement plane, each set having at least two interferometer beams used to perform position measurements along respective beam directions specific to each set; The beam directions of the two sets are different from each other; The geometric extensions of the different sets of interferometer beams intersect at crossing points, where at least two of the crossing points are used as reference measurement points for calculating the actual position and orientation of the target. [Appendix 18] In the above method, particularly in any of the methods of Appendices 1 to 17, The particle-optical columns are arranged in the charged particle beam array and for each base point according to a predetermined array, and within the predetermined array, the particle-optical columns form at least two rows (or columns) extending parallel to a main direction of motion of the target, the at least two rows being spaced apart from each other by a row offset measured in a direction perpendicular to the main direction.

[0070] [Appendix 1'] A method for controlling the relative positioning of a moving target and a charged particle beam array. the charged particle beam array includes a plurality of charged particle beams generated by a plurality of particle optical columns in a charged particle multi-beam processing apparatus for exposure of a target; the target is moved through a predetermined series of target movement positions within a target plane using a target stage of the charged particle multi-beam processing apparatus; the plurality of particle-optical columns are arranged along respective longitudinal axes that intersect (pass through) the target surface at respective base points, and each particle-optical column is configured to generate a respective charged particle beam and project the generated charged particle beam onto the target in a respective region around the respective base point to generate a pattern sub-image in the region according to a pattern to be exposed on the target; The method comprises: providing the charged particle multi-beam processing apparatus including the plurality of particle optical columns; Providing distance measurement systems (ranging systems); and measuring the current position of the target using the distance measurement system; Including, the distance measurement system is configured to measure positions of at least two predetermined reference measurement points of the target within the target stage in a measurement plane that is coincident with or substantially parallel to the target surface; The measurement of the position of the reference measurement point is used to calculate the actual position and orientation of the target. [Appendix 2'] In the method of Appendix 1', the distance measurement system includes an interferometer system using two sets of interferometer beams propagating in the measurement plane, each set having at least two interferometer beams used to perform position measurements along respective beam directions specific to each set; The two sets of beam directions are different from each other; The geometric extensions of the different sets of interferometer beams intersect at crossing points, at least two of which are used as reference measurement points for calculating the actual position and orientation of the target. [Appendix 3'] In the method of Appendix 2', The reference measurement point is within the geometric projection of a pattern sub-image on the measurement surface. [Appendix 4'] In any of the methods of appendices 1' to 3', The method comprises: calculating a target deviance, wherein the target deviance represents a deviation of the calculated position and orientation of the target from its associated nominal target motion position and orientation; and calculating, for at least one of the particle-optical columns, a displacement of the position of the fiducial point of each particle-optical column corresponding to the target displacement applied to the position of the fiducial point and a beam displacement for the beam of each particle-optical column compensating for the respective displacement. Further includes: [Appendix 5'] In any of the methods of appendices 1' to 4', The method comprises: For each position in the series of target motion positions, referred to as the current target position, the following steps are performed: (i) positioning the target toward the current target position using a mechanical target stage system, thereby achieving an initial target position that is close (approximate) to the current target position; (ii) measuring the initial target position at a position corresponding to the reference measurement point to obtain initial target position coordinates; (iii) calculating a lateral displacement of the target and a stage azimuth angle at the initial target position relative to the current target position using the initial target position coordinates and the coordinates of the reference measurement point; (iv) calculating, for each particle-optical column and its respective beam, beam displacements and orientation corrections that compensate for differences between the initial target position for the current target position and the calculated stage azimuth angle for the position of the origin of each particle-optical column; and (v) applying to each beam a correction for the position and orientation of each beam image on the target according to the respective beam displacement and orientation corrections; Further includes: [Appendix 6'] In the method of appendix 4' or 5', Beam displacements are calculated taking into account the actual position of the origin of the particle optical column within the charged particle beam array, and for each particle optical column, the respective beam displacements are calculated by interpolating the lateral displacements or respective offsets from the lateral displacements determined at the reference measurement points to the respective actual positions of the origins of the particle optical column within the charged particle beam array. [Appendix 7'] In the method of Appendix 6', The position of the origin of the particle-optical column is determined using an initial calibration process; In the initial calibration process, a test substrate is exposed by a writing process in which each of the particle optical columns writes a test pattern onto the test substrate; The position of the test pattern is measured; The positions so measured are compared with the nominal positions of the respective particle-optical columns and the deviations from the nominal positions are stored. [Appendix 8'] In the method of Appendix 7', The test patterns are copies of a template pattern, which includes a pattern shape, such as a cross or a star, having multiple components arranged radially around a central location. [Appendix 9'] In any of the methods of appendices 6' to 8', For each particle-optical column, a deviation of the actual position of each fiducial from a respective nominal position of each fiducial is determined by measuring the difference between the nominal position and a measured position for each particle-optical column for a plurality of test locations, the plurality of test locations spanning a range of positions sampling a desired range of motion of the target stage, and based on the deviations so determined, a position error map is generated using a predetermined interpolation method for the deviations between the locations of the test locations, the position error map representing the deviations of the particle-optical column as a function of the position of the nominal fiducial. [Appendix 10'] In the method of Appendix 9', During execution of a drawing process involving exposure of the target in the charged particle multi-beam processing apparatus, the measurement results of the position of the reference measurement point are applied to the position of the particle optical column used to correct the position of the beam image generated on the target by the particle optical column, and the position of the column is adjusted [in real time] using the position error map. [Appendix 11'] In any of the methods of appendices 1' to 10', The reference measurement points each correspond to the position of the origin of the corresponding particle-optical column. [Appendix 12'] In any of the methods of appendices 1' to 11', The particle-optical columns are arranged in the charged particle beam array and for each base point according to a predetermined array, and within the predetermined array the particle-optical columns form at least two rows extending parallel to a main direction of motion of the target, the at least two rows being spaced apart from each other by a row offset measured in a direction perpendicular to the main direction. [Appendix 13'] In any of the methods of appendices 1' to 12', Measurement of the current position of the target and, if applicable, calculation of a beam displacement for the beam that compensates for deviation of the current target position from a nominal position is performed during a writing process performed on a substrate positioned at the position of the target. [Appendix 14'] In the method of Appendix 13', The measurement of the target's current position and, if applicable, the calculation of the beam displacement are carried out within a total time not exceeding a predetermined delay time, which is preferably 10 μs. [Appendix 15'] In any of the methods of appendices 1' to 14', Processing circuitry, including one or more field programmable gate arrays (FPGAs), is used to perform or control the steps of determining the current position of the target and, optionally, for further calculations based thereon.

[0071] Within the scope of the entire disclosure of the present invention (including the claims and drawings), modifications and adjustments of the embodiments are possible based on the basic technical concept thereof. Furthermore, within the scope of the entire disclosure of the present invention, various combinations and selections (including "non-selection") of various disclosed elements (including each element of each claim, each element of each embodiment, each element of each drawing, etc.) are possible. In other words, the present invention naturally includes various modifications and alterations that would be possible by a person skilled in the art in accordance with the entire disclosure, including the claims and drawings, and the technical concept of the present invention. In particular, with regard to the numerical ranges described herein, any numerical value or subrange included within the range should be construed as being specifically described, even if not otherwise specified.

[0072] Furthermore, the reference numerals in the drawings attached in the claims are intended solely to aid in the understanding of the invention and are not intended to limit the invention to the embodiments and examples shown.

[0073] Furthermore, the entire contents of each of the above references are incorporated herein by reference.

Claims

1. 1. A method for controlling the relative positioning of a movable target and a charged particle beam array, comprising: the charged particle beam array comprises a plurality of charged particle beams generated by a plurality of particle optical columns (109) in a charged particle multi-beam processing device (1) for exposure of a target (107); The target is moved through a predetermined series of target movement positions within a target plane using a target stage (105) of the charged particle multi-beam processing device (1); the plurality of particle-optical columns (109) are arranged along respective longitudinal axes that traverse (pass through) the target surface at respective base points, and each particle-optical column (109) is configured to generate a respective charged particle beam and project it onto the target in a respective region around its respective base point to generate a pattern sub-image in that region according to a pattern to be exposed on the target; The method comprises: providing the charged particle multi-beam processing device (1) including the plurality of particle optical columns; Providing a distance measurement system (ranging system); and measuring the current position of the target using the distance measurement system; Including, the distance measurement system is configured to measure positions of at least two predetermined reference measurement points of the target within the target stage in a measurement plane that is coincident with or substantially parallel to the target surface; The measurement results of the position of the reference measurement point are used to calculate the actual position and orientation of the target. A method characterized by:

2. 10. The method of claim 1, the distance measurement system includes an interferometer system using two sets of interferometer beams propagating in the measurement plane, each set having at least two interferometer beams used to perform position measurements along respective beam directions specific to each set; the beam directions of the two sets are different from each other; The geometric extensions of the different sets of interferometer beams intersect at crossing points, and at least two of the crossing points are used as reference measurement points for calculating the actual position and orientation of the target. A method characterized by:

3. 3. The method of claim 2, The reference measurement point is within a geometric projection of a pattern subimage on the measurement surface. A method characterized by:

4. The method according to any one of claims 1 to 3, calculating a target deviance, wherein the target deviance represents a deviation of the calculated position and orientation of the target from its associated nominal target motion position and orientation; and calculating, for at least one of the particle-optical columns, a displacement of the location of the origin of each particle-optical column corresponding to the target displacement to be applied to the location of the origin, and a beam displacement for the beam of each particle-optical column compensating for the respective displacement. Further comprising A method characterized by:

5. The method according to any one of claims 1 to 4, For each position in the series of target motion positions, referred to as the current target position, the following steps are performed: (i) positioning the target toward the current target position using a mechanical target stage system, thereby achieving an initial target position close to the current target position; (ii) measuring the initial target position at a position corresponding to the reference measurement point to obtain initial target position coordinates; (iii) calculating a lateral displacement of the target and a stage azimuth angle at the initial target position relative to the current target position using the initial target position coordinates and the coordinates of the reference measurement point; (iv) calculating, for each particle-optical column and its respective beam, beam displacements and orientation corrections that compensate for differences between the initial target position for the current target position and the calculated stage azimuth angle for the position of the origin of each particle-optical column; and (v) applying to each beam a correction of the position and orientation of each beam image on the target according to the respective beam displacement and orientation correction; Further comprising A method characterized by:

6. 6. The method according to claim 4 or 5, beam displacements are calculated taking into account actual positions of origins of the particle optical columns within the charged particle beam array, and for each particle optical column, the respective beam displacements are calculated by interpolating the lateral displacements or respective offsets from the lateral displacements determined at the reference measurement points to the respective actual positions of the origins of the particle optical columns within the charged particle beam array. A method characterized by:

7. 7. The method of claim 6, the position of the particle-optical column origin is determined using an initial calibration process; In the initial calibration process, a test substrate is exposed by a writing process in which each of the particle optical columns writes a test pattern onto the test substrate; The position of the test pattern is measured; The positions so measured are compared with the nominal positions of the respective particle-optical columns and the deviations from said nominal positions are stored. A method characterized by:

8. 8. The method of claim 7, The test pattern is a plurality of copies of a template pattern, the template pattern including a pattern shape, such as a cross or a star, having multiple components arranged radially around a central location. A method characterized by:

9. The method according to any one of claims 6 to 8, For each particle-optical column, a deviation of the actual position of each respective fiducial point from a respective nominal position of each respective fiducial point is determined by measuring the difference between the nominal position and a measured position for each particle-optical column for a plurality of test locations, the plurality of test locations spanning a range of positions sampling a desired range of motion of the target stage, and based on the deviations so determined, a position error map is generated using a predetermined interpolation of the deviations between the test location locations, the position error map representing the deviations of the particle-optical column as a function of the position of the nominal fiducial point. A method characterized by:

10. 10. The method of claim 9, During the execution of a writing process involving exposure of the target (107) in the charged particle multi-beam processing device (1), the measurement results of the positions of the reference measurement points are applied to the position of the particle optical column used for correcting the position of the beam image generated on the target by the particle optical column, and the position of the column is adjusted [in real time] using the position error map. A method characterized by:

11. The method according to any one of claims 1 to 10, The reference measurement points each correspond to the position of the origin of the corresponding particle optical column. A method characterized by:

12. The method according to any one of claims 1 to 11, the particle-optical columns are arranged in the charged particle beam array and with respect to each fiducial point according to a predetermined array, the particle-optical columns form at least two rows within the predetermined array extending parallel to a main direction of motion of the target, the at least two rows being spaced apart from each other by a row offset measured in a direction perpendicular to the main direction. A method characterized by:

13. The method according to any one of claims 1 to 12, The measurement of the current position of the target and, if applicable, the calculation of a beam displacement for the beam compensating for the deviation of the current position of the target from a nominal position are performed during a writing process performed on a substrate positioned at the position of the target. A method characterized by:

14. 14. The method of claim 13, The measurement of the target's current position and, if applicable, the calculation of the beam displacement are carried out within a total time not exceeding a predetermined delay time, which is preferably 10 μs. A method characterized by:

15. The method according to any one of claims 1 to 14, a processing circuit including one or more field programmable gate arrays (FPGAs) is used for performing or controlling the step of determining the current position of the target and, optionally, for further calculations based thereon; A method characterized by:

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