Correcting aberration and apodization of optical system using correction plates

Abstract

To solve the problem in which, as semiconductor devices get smaller, the demands on optical inspection or metrology during the manufacturing process become greater, and precise aberration control of the wavefront profile is needed.SOLUTION: An optical system with aberration correction is disclosed. The optical system may include an illumination source. The optical system may include a detector. The optical system may include one or more collection optics configured to image a sample onto the detector based on illumination from the illumination source. The optical system may include two or more aberration correction plates located in one or more pupil planes of the one or more collection optics. The two or more aberration correction plates may provide at least partial correction of two or more linearly independent aberration terms. Any particular one of the two or more aberration correction plates may have a spatially varying thickness profile providing a selected amount of correction for a single particular aberration term of the two or more linearly independent aberration terms.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] This disclosure relates generally to correcting wavefront deformations, and more particularly, to correcting wavefront deformations using one or more aberration correction plates. This relates to correcting wavefront deformation using a hologram. [Background technology]

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a part of the "CORRECTION PLATES" application filed on February 3, 2021. OF LOW-ORDER ZERNIKE ABERRATIONS AND APO "DISIGNATURE FOR A HIGH IMAGING SYSTEM" Haifeng Huang, Rui-Fang Shi, Joseph Wals h, Mitchell Lindsay and Eric Vella as inventors. Claiming the benefit under 35 U.S.C. § 119(e) of Application No. 63 / 144,996 No. 6,239,999, which is incorporated herein by reference in its entirety.

[0003] Optical inspection or metrology in the semiconductor industry uses diffraction-limited high numerical aperture (NA) systems. may be used to generate measurements based on light collected from the sample. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent Application Publication No. 2011 / 0199884 Summary of the Invention [Problem to be solved by the invention]

[0005] As semiconductor devices become smaller, the demand for optical inspection or metrology during the manufacturing process increases. In particular, precise aberration control of the wavefront profile is required. [Means for solving the problem]

[0006] In accordance with one or more embodiments of the present disclosure, an optical system with aberration correction is disclosed. The system includes an illumination source. The system includes a detector. The system detects illumination from the illumination source. and one or more collection optics configured to image the sample onto a detector based on the The system may include two or more aberration correction lenses located at one or more pupil planes of one or more focusing optics. a positive plate, which provides at least partial correction of two or more linearly independent aberration terms, Any particular one of the two or more aberration correction plates may have a spatially varying thickness profile. a selected quantity for a single specific aberration term among two or more linearly independent aberration terms provides correction for

[0007] In some embodiments, the system at least partially corrects for apodization. The optical fiber may further include at least one apodization correction plate configured to:

[0008] In some embodiments, at least one of the two or more aberration correction plates is an apodized plate. The method may be configured to at least partially correct for the chromatic aberration.

[0009] In some embodiments, at least one of the two or more aberration correction plates is an apodized plate. The optical system may be configured to at least partially correct for two or more aberrations. At least one of the correction plates has an apodization coating and at least When another aberration correction plate is placed in the pupil plane of the optical system, the center of the pupil of the optical system The radial variation function of the transmittance from the pupil increases towards the outer edge of the pupil. an apodizer configured to change the transmittance radially according to a ing function This may be because it may include a coating.

[0010] In some embodiments, the two or more aberration correction plates characterize a first type of aberration. a first aberration correction plate configured to at least partially correct a first aberration term; configured to at least partially correct a second aberration term characterizing the second type of aberration. In some embodiments, the first type of aberration correction plate may include a second aberration correction plate. and at least one of the second type of aberrations is astigmatism, coma, spherical aberration, or It may be one of the trefoil aberrations.

[0011] In some embodiments, the two or more aberration correction plates are and a third aberration correction plate configured to at least partially correct the aberration term of In some embodiments, the third aberration term may be a third type of aberration of the optical system. where the third type of aberration, the second type of aberration, and the first type of aberration are The types of aberrations are different.

[0012] In some embodiments, the third type of aberration may be spherical aberration.

[0013] In some embodiments, the first aberration correction plate is a first aberration correction plate of the optical system. configured to at least partially correct the first aberration term when positioned at one or more pupil planes; The second aberration correction plate may be positioned at one or more pupil planes of the optical system. The second aberration term may be at least partially corrected when the second aberration term is positioned.

[0014] In some embodiments, the first aberration correction plate is configured to at least partially correct the first aberration term when positioned at the first pupil plane; The second aberration correction plate may be arranged such that the second aberration correction plate is arranged at one or more pupil planes different from the first pupil plane. and at least partially correcting the second aberration term when located at a second pupil plane that may be It can be configured as follows.

[0015] In some embodiments, each of the two or more linearly independent aberration terms is a Zernike term. That's fine.

[0016] In some embodiments, each of the two or more linearly independent aberration terms is selected from the Zernike 5 terms It may also be a lower order Zernike term in the span up to and including the 9 Zernike terms.

[0017] In some embodiments, the optical system may be an imaging tool.

[0018] In some embodiments, the aberration types astigmatism, coma, or trefoil aberration are Any aberration correction plate containing aberration terms characterizing the aberration types in the optical system can be rotated. The orientation of the optical fiber 100 may be configured to align with the optical fiber 100 orientation.

[0019] In some embodiments, any aberration correction plate located at one or more pupil planes may include one or more The aberration correction lens may be positioned within a distance range from the pupil plane, where the distance range allows for correction of the aberration within a selected tolerance. The ion exchanger 100 may be configured to perform a positive

[0020] In accordance with one or more embodiments of the present disclosure, a system with aberration correction is disclosed. The system includes an illumination source. The system includes a detector. The system detects a signal based on illumination from the illumination source. The system includes one or more collection optics configured to image the sample onto the detector. The system contains a catalog of aberration correction plates. The catalog contains two or more sets. Each of the above sets provides at least partial correction of a specific linearly independent aberration term. Any particular one of the two or more aberration correction plates may be providing a selected amount of correction for a particular one of the above linearly independent aberration terms. Each set has a different, specific, linearly independent convergence profile. The optical system includes a selected combination of two or more aberration correction plates. , at least partially correcting the aberrations within the selected tolerances. The aberration corrector plate is one aberration corrector plate of a set of two or more.

[0021] In some embodiments, the catalog is at least partially corrected for apodization. The apodization set may further include an apodization set configured to may include an apodization correction plate of the apodization set.

[0022] In some embodiments, at least one aberration correction plate of the selected combination is It may be configured to at least partially correct for podization.

[0023] In some embodiments, at least one aberration correction plate provides a small amount of apodization. at least partially correcting the aberrations, because at least one aberration corrector plate In at least one embodiment, the coating may include an apodization coating. Apodization coatings are used when at least one aberration correction plate is used in an optical system. When placed in the pupil plane, the transmittance of an optical system from the center of the pupil increases relative to the outer edges of the pupil. The transmittance is changed radially in response to a radial change function of the state of the light source. This is because it can be done.

[0024] In some embodiments, the selected combination is adjustable to accommodate different optical system configurations. The following configurations can be provided.

[0025] In some embodiments, the optical system may be an imaging tool.

[0026] In some embodiments, the plurality of aberration terms may include astigmatism.

[0027] In some embodiments, the plurality of aberration terms may include coma.

[0028] According to one or more embodiments of the present disclosure, a method for correcting aberrations in an optical system is disclosed. The method includes determining wavefront aberrations of an optical system. The method includes determining a wavefront aberration of an optical system. The method includes providing one or more aberration correction plates, each of which has a plurality of aberration correction plates. The optical system is configured to at least partially correct one of the aberration terms. Each of the terms is linearly independent of the others and is constructed to characterize a type of aberration. , each aberration term characterizes a type of aberration in the optical system and is based on the determined wavefront aberrations. do.

[0029] In some embodiments, at least one aberration correction plate of the two or more aberration correction plates may be configured to at least partially correct for apodization.

[0030] In some embodiments, at least one aberration correction plate provides a small amount of apodization. at least partially correcting the aberrations, because at least one aberration corrector plate may include an apodization coating, the apodization coating comprising: When at least one aberration correction plate is disposed in the pupil plane of the optical system, According to the radial variation function of the state where the transmittance from the center of the pupil increases towards the outer edge of the pupil, , because it can be configured to vary the transmittance in the radial direction.

[0031] In some embodiments, the determining comprises measuring wavefront aberrations of the optical system. It may include.

[0032] In some embodiments, the determining step includes simulating wavefront aberrations of the optical system. This may include:

[0033] In some embodiments, each of the plurality of aberration terms may be a Zernike term.

[0034] In some embodiments, the plurality of aberration terms may include astigmatism, coma, spherical aberration, or trajectory aberration. The aberrations may include at least one of the following:

[0035] In some embodiments, a first time of a first aberration correction plate of the two or more aberration correction plates The type of aberration is one of astigmatism, coma, spherical aberration, or trefoil aberration. It is possible.

[0036] In some embodiments, a second timing of a second aberration correction plate of the two or more aberration correction plates The type of aberration is one of astigmatism, coma, spherical aberration, or trefoil aberration. It is possible.

[0037] In some embodiments, the first type of aberration of the first aberration correction plate is astigmatism. For example, in some embodiments, the amplitude of the first aberration correction plate may be adjusted to Zernike 5 astigmatism term and Zernike 6 astigmatism term, which may be based on the determined wavefront aberration. The first aberration correction plate is then placed in the pupil plane of the optical system. and rotated to align with the direction of a first type of aberration of the optical system. configured to at least partially correct both the Zernike 5 and Zernike 6 terms when It can be done.

[0038] In some embodiments, the second type of aberration of the second aberration correction plate is coma. For example, in some embodiments, the amplitude of the second aberration correction plate may be adjusted to Zernike 7 term of coma and Zernike 8 term of coma may be based on the determined wavefront aberration. The second aberration correction plate is then placed in the pupil plane of the optical system. and rotated to align with the direction of a second type of aberration of the optical system. configured to at least partially correct both Zernike 7 and Zernike 8 terms when It can be done.

[0039] In some embodiments, the optical system may be an imaging tool.

[0040] In some embodiments, the method at least partially corrects for apodization. The method may further include providing an apodization correction plate configured to:

[0041] In accordance with one or more embodiments of the present disclosure, an optical system with aberration correction is disclosed. The system includes an illumination source. The system includes a detector. The system detects a signal based on illumination from the illumination source. and one or more collection optics configured to image the sample onto the detector. The stem is positioned at one or more pupil planes of one or more focusing optical elements to form one or more linearly independent one or more aberration correction plates that provide at least partial correction of aberration terms, where one or more Any particular one of the aberration correction plates has a spatially varying thickness profile, providing a selected amount of correction for a single specific aberration term among one or more linearly independent aberration terms; The one or more aberration correction plates reduce a first aberration term that characterizes a first type of aberration. a first aberration correction plate configured to partially correct both The aberration is either astigmatism, coma, or trefoil aberration, where astigmatism Any aberration correction including aberration terms characterizing the aberration types of coma, tf, or trefoil aberrations. The plate is configured to be rotated to align with the direction of the aberration type of the optical system. .

[0042] In accordance with one or more embodiments of the present disclosure, a system with aberration correction is disclosed. The system includes an illumination source. The system includes a detector. The system detects a signal based on illumination from the illumination source. The system includes one or more collection optics configured to image the sample onto the detector. The system contains a catalog of aberration correction plates. The catalog contains one or more sets. Each of the above sets provides at least partial correction of a particular linearly independent aberration term. Any particular one of the one or more aberration correction plates may be providing a selected amount of correction for a particular one of the above linearly independent aberration terms. Each set has a spatially varying thickness profile with a different specific linearly independent aberration. Each specific linearly independent aberration term corrects for one or more types of aberration. characterizing a type of aberration, where each type of aberration among one or more types of aberration is an astigmatism The optical system may have one or more of the following aberrations: aberration correction plates, which at least partially correct aberrations within a selected tolerance. Each aberration corrector plate in the selected combination is one of one or more sets. where the aberration type of astigmatism, coma, or trefoil aberration is The aberration correction plate containing the characterizing aberration terms is rotated to orient the aberration types of the optical system. The alignment is configured to:

[0043] According to one or more embodiments of the present disclosure, a method for correcting aberrations in an optical system is disclosed. The method includes determining wavefront aberrations of an optical system. and providing one or more aberration correction plates, each of which includes one or more aberration correction plates. The optical system is configured to at least partially correct one of the aberration terms. Each of the above aberration terms is linearly independent of each other and is configured to characterize a type of aberration. Each aberration term characterizes a type of aberration in the optical system and is based on the determined wavefront aberrations. The one or more aberration correction plates are configured to at least partially correct the first aberration term. the first aberration term characterizes a first type of aberration, The first type of aberration is one of astigmatism, coma, or trefoil aberration. where the aberration terms characterizing the aberration type of astigmatism, coma, or trefoil aberration are Any aberration correction plate, including It is configured to:

[0044] Both the foregoing general description and the following detailed description are exemplary and explanatory only. It should be understood that these are not necessarily limitations on the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and are included in the general description. It also serves to illustrate the principles of the present invention. [Brief explanation of the drawings]

[0045] Many advantages of the present disclosure can be better understood by those skilled in the art by reference to the following drawings. It will be understood. [Figure 1A] 1 shows a diagrammatic representation of at least partially correcting wavefront aberrations in an optical system using one or more aberration correction plates, in accordance with one or more embodiments of the present disclosure. [Figure 1B] 1 shows a diagrammatic representation of a catalog of one or more sets of aberration correction plates configured to at least partially correct wavefront aberrations of an optical system, in accordance with one or more embodiments of the present disclosure. [Figure 1C] 1 shows a diagrammatic representation of an imaging tool in accordance with one or more embodiments of the present disclosure. [Figure 2] 1 shows a flow diagram illustrating a method or process for correcting aberrations in an optical system in accordance with one or more embodiments of the present disclosure. [Figure 3A] 1 illustrates an astigmatic Zernike 5-term wavefront in accordance with one or more embodiments of the present disclosure. [Figure 3B] 1 illustrates a Zernike 7-term wavefront for coma in accordance with one or more embodiments of the present disclosure. [Figure 3C] 1 illustrates a Zernike 9-term wavefront of spherical aberration in accordance with one or more embodiments of the present disclosure. [Figure 4A] 1 shows a diagrammatic representation of exemplary Zernike 5 and Zernike 6 term sinusoidal projections, in accordance with one or more embodiments of the present disclosure. [Figure 4B] 10 shows a graphical representation of simulated residual astigmatism RSS values after aberration correction with an imperfect aberration correction plate, in accordance with one or more embodiments of the present disclosure. [Figure 5A] 10A-10C show diagrammatic representations of exemplary Zernike 7 and Zernike 8 term sinusoidal projections, in accordance with one or more embodiments of the present disclosure. [Figure 5B] 10 shows a graphical representation of simulated residual coma RSS values after aberration correction with an imperfect aberration correction plate, in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0046] The present disclosure has been particularly shown and described with respect to certain embodiments and certain features thereof. The embodiments described herein are to be considered illustrative rather than limiting. Various changes and modifications in form and detail may be made without departing from the spirit and scope of the present disclosure. It will be readily apparent to one skilled in the art that the presently disclosed subject matter can be readily accomplished. and which is shown in the accompanying drawings.

[0047] 1-5B, in accordance with one or more embodiments of the present disclosure, an optical system Systems and methods for correcting aberrations and / or apodization of a lens are disclosed. Embodiments of the present disclosure may reduce wavefront aberrations and / or apodization of an optical system. one or more aberration and / or apodization corrections configured to correct at least partially It is related to providing positive plates, where each aberration correction plate corrects a different aberration term.

[0010] Another embodiment relates to one or more aberration correction plates, each plate being selected for a single aberration type. A further embodiment provides an optical system including first and second aberration correction plates. wherein the first and second aberration correction plates characterize different aberration types of the optical system. Corrects different aberration terms in the

[0048] Further embodiments provide for flexible adjustment of aberration and / or apodization correction of the optical system. Includes a catalog of aberration and / or apodization corrector plates that can be used to adjust the , relates to a system for correcting aberrations in an optical system. An embodiment may include two or more aberration correction plates in each set (additionally or solely apodization plates). and a system including a catalog having one or more sets of Each set is associated with an aberration term (e.g., astigmatism, coma, etc.) and the value of that aberration term (e.g., the first step to correct astigmatism at 20 mW) 1 plate, a second plate to correct the 40mWave astigmatism, etc.).

[0049] Wavefront measurement and control is generally important for high-resolution optical systems operating near the diffraction limit. Undesirable optical aberrations present in an optical system can cause image distortion. , which causes image contrast degradation and Strehl loss. Therefore, the optical aberration is , which is closely related to the system performance and quality of the optical system.

[0050] Generally, the circular wavefront aberration profile is mathematically modeled using Zernike polynomials. The Zernike polynomials are orthogonal on a circle with unit radius. Complex wavefront aberrations can be expressed as Zernike polynomials. Fitted with Nike polynomials to obtain a set of fitting coefficients, Each fitting coefficient of represents a different linearly independent type of aberration. The Zernike terms (i.e., Zernike polynomials multiplied by their respective coefficients) represent the total wavefront convergence. The aberration types that contribute to the difference can be quantified individually and in isolation. Note that Zernike polynomials may exist.

[0051] Here, it is possible to correct multiple aberrations in an optical system using a single element. For example, if a single aberration correction plate is used to correct multiple aberrations, This is generally described in U.S. Patent No. 10,761,031 as "ARBITRARY WAV EFRONT COMPENSATOR FOR DEEP ULTRAVIOLET( It is described under the title "DUV OPTICAL IMAGING SYSTEM" and is incorporated herein by reference in its entirety. In another example, the focus (Z4) and astigmatism (Z5 and Z6) can be simultaneously corrected using a dependent combination of at least two plates. ,Generally, "PROCESS FOR CORRECT USE" published on October 12, 1999 U.S. Patent No. 6,399,363 entitled "Ejecting Wave Front Deformations" No. 5,966,243, the entire contents of which are incorporated herein by reference. However, it is noted herein that this approach may have limitations. For example, various types of aberrations in optical systems (e.g., coma, astigmatism, etc.) A single aberration correction plate that corrects for aberrations such as A set of single aberration correction plates can be used for all possible ranges of values for each type of aberration. It is practical to prepare a system that can simultaneously correct all possible combinations. Therefore, a single aberration correction system that simultaneously corrects various types of aberrations is not recommended. The plate may essentially be tied to its own individual optical system for which it was designed. Any modification of the optical system may change the wavefront aberrations of the optical system, It requires a separate aberration correction plate, which increases costs and can cause significant delays. For example, as aberration tolerance requirements become more stringent, critical components such as high numerical aperture (NA) The production cost and lead time may increase due to the need for objective lenses with a high NA. If the optical aberration of the objective lens exceeds the tolerance requirements, replace the components to reduce the aberration. Converting data can be costly and can result in significant delays.

[0052] Some embodiments address at least some of these concerns by using a convergence For example, in some applications, aberration correction may be used. To provide an optical system in which an image can be generated using one or more aberration correction plates In this example, the change in wavefront aberration of the optical system can be corrected by one or more correction plates. and the correction plate is uniquely designed for the optical system. For example, the wavefront aberrations of an optical system may be corrected by using one or more aberration correction plates. Thus, each aberration correction plate can at least partially correct a different linearly independent correction of the wavefront aberration. Correct the difference term.

[0053] In this regard, or as another example, a catalog of aberration correction plates may be used, The lens contains at least one set of corrector plates that correct all the different amounts of a particular aberration term. For example, the catalog may include a set of aberration correction plates to correct astigmatism; Each plate has a different compensation amount (e.g., 5mWave, 10mWave, 15mWave, etc.) In this way, the astigmatism in a particular optical system can be adjusted to provide the required amount of correction. By using (or selecting) a suitable plate, the correction can be made within a selected tolerance. The catalog may include multiple (e.g., two or more) sets of correction plates, each set having a different Therefore, the complex aberrations in an optical system are corrected from different sets of By utilizing (or selecting) multiple plates from the above, compensation can be achieved within a selected tolerance.

[0054] Note that apodization is the change in the transmission of light across the pupil. A uniform pupil transmission corresponds to a small apodization. Desirable for high NA systems because large apodization increases the effective NA of the system. Apodization (i.e. pupil transmission) of high NA optical systems Note that λ may exhibit higher transmission near the pupil center than near the pupil edge of an optical system. I want to be.

[0055] At least some embodiments of the present disclosure include an apodization correction plate, which It may also be an aberration correction plate with apodization correction.

[0056] Regarding apodization, as further explained in the optional steps below: In at least some embodiments, at least one aberration correction plate in a catalog of aberration correction plates The front plate (e.g., 118a) has an apodization coating at least as large as the aberration correction plate. For example, an apodization coating may be applied to the surface of an optical system. It may be configured to at least partially correct for non-uniformity in pupil transmission.

[0057] For example, each aberration correction plate in the set may at least partially correct a particular value of a range of values for a particular aberration term. The set may be dynamically corrected and may span a range of values for a particular aberration term. Changes in the optical system can cause changes in the wavefront aberrations of the optical system. Regarding wavefront aberration, the existing aberration correction plate of the optical system has specific values of specific aberration terms. , by replacing the selected aberration correction plate with a different value of the same aberration term, In another embodiment of this example, the selected aberration correction plate may be an existing Furthermore, for this example, the selected aberration correction plate Corrector plates may already be in stock and / or mass produced, so The cost of such aberration correction plates is relatively low and the lead time is relatively short. By virtue of the system or method, at least some embodiments may be able to correct one or more aberration types (e.g., We have a catalog of aberration correction plates that cover aberrations such as coma, astigmatism, and spherical aberration. (or purchase one or more aberration correction plates in a relatively short time) to add aberration correction plates to your optical system. , the ability to quickly replace (or add) as the wavefront aberration of the optical system changes. Furthermore, such a system and method may be implemented in some embodiments. This will at least make it possible to reduce the cost of correcting aberrations in optical systems, This is because such aberration correction plates can be used in multiple systems and can be mass-produced. and / or because they are easier to manufacture than a single plate that corrects for various aberration terms.

[0058] At least some embodiments of the present disclosure are usable in optical systems (e.g., pupil plane For example, the aberration correction plate may be inserted into an optical system (e.g., an image sensor). A variable two-dimensional (2D) optical system is provided on the optical system, configured to be used at or near the pupil plane. 2D thickness can be achieved by ion beam machining (I BF) technology or other profile definition technology or method, and As a result, the transmitted wavefront profile from the aberration correction plate varies depending on the orientation of the plate (i.e., the orientation of the optical system). The optical system will have fewer aberrations if the rotation around the optical axis is correct or nearly correct. In this regard, the aberration correction plate is The optical path of the light can be spatially altered to cancel (eg, compensate for) the wavefront aberrations.

[0059] It is further noted that optical systems with aberration correction can be used in a wide range of applications. Thus, the spirit and scope of the present disclosure is not limited to high NA or high resolution metrology systems; It can be extended to any application of an optical system with one or more aberration correction plates.

[0060] FIG. 1A is a diagram of an optical system with aberration correction in accordance with one or more embodiments of the present disclosure. In one embodiment, the optical system 100 includes one or more Aberration correction plates 110 (e.g., a first aberration correction plate 110a and, optionally, a second aberration correction plate plate 110b, up to N-th aberration correction plate 110n, each correcting an aberration term. For example, as shown, optical system 100 includes imaging optics 104. The optical system may include any suitable number and type of imaging optics. The optical system images an object 102 through the use of electromagnetic waves (e.g., light from a light source) and 106, and the electromagnetic waves are reflected from the object 102 or from the object 106. 102 (e.g., from a light source located behind the object 102) and 08. The light passes through any number and type of imaging optics 104. Each element of the imaging optics 104 may introduce aberrations into the system, which As a result, the wavefront appears distorted as shown by wavefront 112a compared to the ideal undistorted wavefront 112b. For example, imperfections in the elements or the elements of the imaging optics 104 may cause distortions. Incorrect placement or orientation of the radiator 104 can cause aberrations and distort the wavefront 108. Furthermore, the design of the optical system 100 itself may be sensitive to aberrations (e.g., the complete imaging optics 104). may introduce a problem (which cannot be avoided for a given set of design constraints, even if the A differential correction plate 110 may be used to compensate (i.e., correct) such a distorted wavefront 112a. One or more aberration correction plates 110 convert the distorted wavefront 112a into a partially corrected wavefront 111b. As shown by 2c, the ideal undistorted wavefront 112b can be more closely approximated. At least some of the advantages of the at least partially corrected wavefront 112c are due to the more severe aberrations. Tolerance requirements can be met, a sharper image can be produced, and / or the object 1 Other advantages include the ability to produce a more accurate and less degraded image of the optical system. At least, the residual wavefront errors caused by the manufacturing steps of the system can be corrected. Also includes.

[0061] With regard to apodization, at least one step may be performed, as further described below. In some embodiments, at least one of the aberration correction plates 110 of the optical system 100 Another aberration correction plate (e.g., 110a) has an apodization coating. At least one surface of the front plate 110 may have an apodization coating. The optical system 100 is configured to at least partially compensate for non-uniformity in pupil transmission. In another example, the apodization coating may provide a lower transmittance (e.g., The optical axis may be configured to have lower transmittance near the center (e.g., optical axis) than near the edges. In the apodization coating, the transmittance increases from the center of the pupil to the radial direction. The transmission may be configured to vary radially according to a variation function.

[0062] FIG. 1B illustrates an optical system (e.g., the optical aberration correction, configured to at least partially correct wavefront aberrations of the system 100; plates (e.g., aberration correction plates 118a of the first set 116a, aberration correction plates 118b of the first set 116a) one or more sets 116a to 116b of correction plates (up to the Nth aberration correction plate of the first set 116a) 16 (e.g., a first set 116a and, optionally, a second set 116b, an Nth 1 is a diagrammatic representation of a catalog 114 of sets (up to 116). In one embodiment, each set 116 is , configured to at least partially correct the aberration terms associated with each set. For example, each aberration term may be linearly independent of each of the other aberration terms, and the type of aberration may be For example, each aberration correction plate 11 of the first set 116a may be configured to characterize 8 is configured to at least partially correct aberration terms related to and characterizing astigmatism. Thus, each aberration correction plate 120 of the second set 116b has an aberration correction function related to and characterizing coma. In this regard, the first set 1 The first aberration correction plate 118a of 16a can correct astigmatism of a value of 20 mWave. The second plate 118b can correct astigmatism of 40 mWave. The scan can continue for the other aberration correction plates 118 of the first set 116a. Similarly, a range of coma values is corrected by the aberration correction plates 120 of the second set 116b. The above example is provided for illustrative purposes only, and the set may include any aberration term and any For example, the aberration terms and aberration types Other examples may not be included simply for the sake of brevity. For example, Catalog 1 14 may include sets 116a associated with linearly independent aberration terms or aberration types. In this example, the catalog 114 includes a set 116a associated with any Zernike term. obtain.

[0063] In another embodiment, at least one of the aberration correction plates in the catalog 114 (e.g., 118a) is an optical system (e.g., optical system 100 of FIG. 1 or the optical system 118b described in detail below). 1C). For example, the aberration correction plate 11 8a may be configured to be inserted into the optical system 100. In another example, an aberration correction plate 118a may be configured to be inserted into one or more pupil planes of optical system 100. In this example, the aberration correction plates 110 from one or more of the one or more sets 116 (e.g., One aberration correction plate 110 from each set is selected for the optical system 100, It may be utilized by the stem 100 or inserted into the optical system 100. For example, an aberration correction plate 118 may be selected from the first set 116a, which is shown in FIG. 1A. Further, for this example, the second set 116 The aberration correction plate 120 may be selected from the aberration correction plate 110b. , the first set 116a at least partially corrects astigmatism, and the second set 116b If at least partially corrects coma, then the aberration correction plates from each set 116 110 in combination, both astigmatism and coma are at least partially It will be corrected.

[0064] Referring again to FIG. 1B, a system for correcting aberrations in an optical system is disclosed. For example, a system may include a catalog. For example, the catalog may include one or more sets. In this regard, the set may include multiple (e.g., two or more) aberration correction plates. For example, each of the multiple aberration correction plates in a set may have a correction coefficient of the aberration terms associated with that set. It may be configured to at least partially compensate for a preset range of catalog values. For example, each aberration term is linearly independent of the other and depends on the type of aberration (e.g., astigmatism, coma, spherical aberration). The optical system may be configured to characterize the optical characteristics (such as surface aberrations).

[0065] In addition, the astigmatism set of the aberration corrector plate, the coma aberration set of the aberration corrector plate, the spherical aberration corrector plate There may be a catalog of aberration sets. Furthermore, the astigmatism set of the aberration correction plate is 2 0mWave first aberration correction plate, 40mWave second aberration correction plate, 60mWave Similarly, the coma corrector set of aberration correctors may include a third aberration corrector set of 10 mW ave first aberration correction plate, 20mWave second aberration correction plate, 30mWave third Similarly, the spherical aberration set of the aberration corrector plate may be set to a predetermined value. Each set of aberration correction plates may be used in the optical system 10. 0. The aberration type associated with each set is used or selected for use. Furthermore, the aberration types may be configured to at least partially correct for: or below a threshold (e.g., 5 mWave) associated with such an aberration type. It may be determined that an aberration correction plate from the selected set will not be used in optical system 100 .

[0066] FIG. 1C is a conceptual diagram illustrating an imaging tool 122, in accordance with one or more embodiments of the present disclosure. In one embodiment, the imaging tool 122 generates at least one illumination beam 126. The illumination from the illumination source 124 is configured to illuminate one or more selected The wavelengths of light may include, but are not limited to, ultraviolet (UV) radiation, visible radiation, or red For example, the imaging tool 122 may include one or more apertures for illuminating a pupil plane. , which splits illumination from an illumination source 124 into one or more illumination beams 126 or illumination lobes. It should be noted that the imaging tool 122 may provide dipole illumination, quadrature illumination, etc. The spatial profile of one or more illumination beams 126 on the sample 128 is determined by a field plane stop. The spatial profile can be controlled by the ion beam splitter to have any selected spatial profile.

[0067] The illumination source 124 may be any type of suitable light source that provides at least one illumination beam 126. In one embodiment, the illumination source 124 is a laser source. For example, the illumination The source 124 may be, but is not limited to, one or more narrowband laser sources, broadband laser sources, In this regard, the illumination may include a supercontinuum laser source, a white light laser source, etc. The source 124 may be a source of high coherence (e.g., high spatial and / or temporal coherence). In another embodiment, the illumination source 124 may provide an illumination beam 126 having a For example, illumination source 124 may include, but is not limited to, a laser-sustained plasma (LSP) source. However, it may include an LSP lamp, an LSP bulb, or an LSP chamber, which are laser sources. and housing one or more elements capable of emitting broadband illumination when excited into a plasma state by In another embodiment, the illumination source 124 includes a lamp source. For example, the illumination source 124 Examples include, but are not limited to, arc lamps, discharge lamps, electrodeless lamps, etc. The illumination source 124 may have low coherence (e.g., low spatial coherence and / or low temporal coherence). In another embodiment, the illumination source may provide an illumination beam 126 having a high coherence. 124 includes a high-intensity illumination source formed from multiple coherent light sources into a single output distribution. For example, multiple coaxial lasers configured to provide a single power distribution at a common etendue may be used. High brightness illumination sources, including coherent light sources, are disclosed in U.S. patent application Ser. No. 2019 / 010999, filed on June 4, 2019. No. 16,430,861, the entire contents of which are incorporated herein by reference. It is used.

[0068] The illumination source 124 provides an illumination beam 126 using free space techniques and / or optical fibers. In one embodiment, the illumination source 124 may provide two or more multi-lobe illumination beams 126. The optical fiber is generated by feeding light into the optical fibers, where the light output from each optical fiber is 1 is an illumination lobe of the bright beam 126. In another embodiment, the illumination source 124 may include two or more light sources. a multi-lobed illumination beam 126 by diffracting the light into diffraction orders The illumination lobe of illumination beam 126 is formed from at least some of the diffraction orders of the light source. Efficient generation of multiple illumination lobes through controlled diffraction is generally Published on the same day, "Efficient Illumination Shaping f U.S. Patent Application Publication No. U.S. 2004 / 0109994 entitled "Method of Scatterometry Overlay" S2020 / 0124408, the entire contents of which are incorporated herein by reference. will be done.

[0069] In another embodiment, the imaging tool 122 directs the illumination beam 126 to the sample 128 via an illumination path. The illumination path 130 modifies and / or conditions the illumination beam 126. and one or more optical elements suitable for directing the illumination beam 126 onto the sample 128. In one embodiment, the illumination path 130 includes one or more illumination path lenses 132 (e.g., For example, to collimate the illumination beam 126, to relay the pupil and / or field plane, etc. In another embodiment, the illumination path 130 includes one or more illumination path optical elements 134. , shape or control the illumination beam 126. For example, the illumination path optics 134 may limit It may include, but is not limited to, one or more field diaphragms, one or more pupil diaphragms, one or more polarizers, one or more filters, one or more beam splitters, one or more diffusers, one or more homogenizers apodizer, one or more apodizers, one or more beam shapers, or one or more mirrors (e.g. The mirror may include a stationary mirror, a translating mirror, a scanning mirror, etc.

[0070] In another embodiment, the imaging tool 122 includes an objective lens 136 and an illumination beam 126 to sample 128 (e.g., target elements located on two or more layers of sample 128). In another embodiment, the sample 128 is focused on a target having a 28 is placed on a sample stage 138 suitable for fixing the sample 28 to the illumination beam 126. The sensor 120 is further configured to position the sample 128 using the sensor.

[0071] In another embodiment, the imaging tool 122 may include a sample 128 (e.g., light emitted from the target (e.g., collected light 150) through collection path 14 2. The collection path 142 includes one or more detectors 140 configured to capture the light through the , one or more optical elements suitable for modifying and / or adjusting the light collection 150 from the sample 128 In one embodiment, the collection path 142 may include one or more collection path lenses 144. (e.g., relaying pupil and / or field planes to collimate illumination beam 126) Although not required to include an objective lens 136, the objective lens 136 may be included. In another embodiment, the collection path 142 includes one or more collection path optical elements 146, The collection path optics 146 may include, but are not limited to, shaping or controlling the collection of light 150. No, but one or more field stops, one or more pupil stops, one or more polarizers, one or more filters one or more beam splitters, one or more diffusers, one or more homogenizers, one or more apodizers, one or more beam shapers, or one or more mirrors (e.g., stationary mirrors, translation mirrors, scanning mirrors, etc.

[0072] The detector 140 may be positioned at any selected location within the collection path 142. In this embodiment, the imaging tool 122 may align the detector 140 with a viewing plane (e.g., conjugate with the sample 128). plane) to generate an image of the sample 128. In another embodiment, the imaging tool 122 , detector 140 is included in the pupil plane (e.g., the diffraction plane) to generate the pupil image. may correspond to the angular distribution of light from sample 128 to detector 140. For example, associated with the diffraction of the illumination beam 126 from 28 (e.g., a target on the sample 128). The diffraction orders that correspond to the diffracted light can be imaged or otherwise observed in the pupil plane. , detector 140 detects reflected (or transmitted), scattered, or diffracted light from sample 128. Any combination may be captured.

[0073] The imaging tool 122 generally captures light from the sample 128 that exhibits overlay. Any suitable number or type of detectors 140 may be included. In one embodiment, detectors 140 include , and one or more detectors 140 suitable for characterizing the static sample. The sample 122 may be operated in a static mode in which the sample 128 is stationary during the measurement. The detector 140 may be a two-dimensional pixel array, such as, but not limited to, a charge coupled device. (CCD) or complementary metal oxide semiconductor (CMOS) devices. , detector 140 may generate a two-dimensional image (eg, a field plane image or a pupil plane image) in a single measurement.

[0074] In one embodiment, the detector 140 detects a moving sample (e.g., a scanned sample). The imaging tool 122 includes one or more detectors 140 suitable for characterizing the It may operate in a scanning mode in which the sample 128 is scanned across the measurement field of view during measurement. For example, , detector 140 measures one or more images for selected image tolerances (e.g., image blur, contrast, have sufficient capture time and / or refresh rate to capture within the scan time (sharpness, etc.) As another example, the detector 140 may include a line scan detector. As another example, a detector may be included to sequentially generate an image of one line of pixels at a time. The detector 140 may include a time delay integration (TDI) detector.

[0075] In another embodiment, the imaging tool 122 includes a controller 152. 2 is configured to execute program instructions held on storage medium 156 or memory. In this regard, one of the controllers 152 may include one or more processors 154. The processor 154 may perform any of the various process steps described throughout this disclosure. Additionally, the controller 152 may control the imaging tool 122 or any component therein. The device may be communicatively coupled to the component.

[0076] In another embodiment, the imaging tool 122 includes a scanning subsystem to measure during metrology measurements. The sample stage 138 scans the sample 128 across the field of view. The sample 128 may be positioned and oriented within the focal volume of the lens 136. The pull stage 138 may include one or more adjustable stages, such as, but not limited to, includes a linear translation stage, a rotation stage, or a tip / tilt stage. Although not shown, the scanning subsystem may include one or more beam scanning optical elements (e.g., , rotating mirror, galvanometer, etc.) to scan the illumination beam 126 across the sample 128 do.

[0077] The illumination path 130 and collection path 142 of the imaging tool 122 are illuminated with the illumination beam 126. The sample 128 is illuminated and the light emitted from the sample 128 in response to the incident illumination beam 126 is The optical fiber can be oriented in a wide variety of configurations suitable for collecting light. For example, as shown in FIG. 1B , the imaging tool 122 may include a beam splitter 148, and the common objective lens 136 , and simultaneously directing the illumination beam 126 toward the sample 128 and collecting light from the sample 128. As another example, the illumination path 130 and the collection path 142 are oriented such that the beam splitter 148 is oriented such that ... Path 142 may include non-overlapping optical paths.

[0078] In one embodiment, the imaging tool 122 includes a first optical filter for at least partially correcting the aberration terms. One or more aberration correction plates 110 (e.g., 118a and 120a in FIG. 1B or 11 in FIG. 1A) For example, as described above, one or more aberration correction plates 110 may include , can be selected from catalog 114.

[0079] In another embodiment, one or more aberration correction plates 110 may be positioned at one or more pupils of the imaging tool 122. and configured to at least partially correct aberrations of the imaging tool 122. For example, the first aberration correction plate 110 may be configured for use at a first pupil plane. , the second aberration correction plate 110 may be configured for use at a second pupil plane. The first aberration correction plate 110 and the second aberration correction plate 110 are configured to be used at the first pupil plane. For example, the first aberration correction plate 110 and the second aberration correction plate 110 may be disposed adjacent to the pupil plane. It can be configured for use on both sides.

[0080] As used herein, the design of a particular optical system 100 may be such that it is located at a particular pupil plane or at a particular pupil plane. The thickness of the aberration correction plates 110 or the number of aberration correction plates 110 that can be placed close enough together is limited, and the selection It is contemplated that the aberration correction plate 110 may provide aberration correction within a selected tolerance. The thickness may be relatively thin (for example, 0.5 mm or less). The thickness may be as thin as possible, and the thinness of the aberration correction plate 110 is determined by the manufacturing method of the aberration correction plate 110. The polishing performance may be limited in part due to the polishing process used to polish the surface.

[0081] For purposes of this disclosure, descriptions showing the placement of one or more aberration correction plates in the pupil plane are provided for selected public and the placement of one or more aberration correction plates within a range of distances from the pupil plane to provide aberration correction within the range of distances. The collimated light wave can be understood as a wave extending beyond the pupil plane (for example, up to 15 cm or more). ) may allow for the same amount of aberration correction within the selected tolerance. For example, a complex objective lens (e.g., a lens having many optical elements) with a pupil plane within the objective lens. ) optical systems with There are cases where it is not possible to place an aberration correction plate inside the objective lens. For example, , must be placed outside the objective lens (e.g., 10 cm from / beyond the pupil plane). In this regard, if the aberration correction plate is arranged over a wide area, it is possible to test, for example, a reticle. When an object is placed in the front focal plane of the objective lens, the light waves passing through the objective lens are When collimated by an objective lens, aberration correction may be possible within selected tolerances. For purposes of this disclosure, "a range of distances from the pupil plane that provides aberration correction within a selected tolerance" is defined as The term "range" in the expression "within" refers to the area in which the light waves pass through the pupil plane and are collimated. It depends on whether the light wave is collimated or not and how collimated it is as it passes through the pupil plane. This may occur.

[0082] For purposes of this disclosure, a description of two or more corrector plates (e.g., aberration corrector plates) shall be construed as one or more At least one of the corrector plates has an aberration type of astigmatism, coma, or trefoil aberration. If it is one of the differences, it is understood to be one or more correction plates (e.g., aberration correction plates). For example, the formulas and other properties described below in relation to Z7 and Z8 can be used to provide The single coma correction plate provided can be referred to in connection with FIGS. 5A and 5B and the method steps Alternatively, two or more aberration correction plates may be provided in the cup 204. For purposes of this disclosure, a statement referring to a catalog of two or more sets refers to one or more of the sets. At least one corrector has an aberration type of astigmatism, coma, or trefoil aberration. If it is one of them, it can be understood to be a catalog of one or more sets.

[0083] Furthermore, the optical system may include any number of optical repeaters and any number of optical repeaters in which an aberration correction plate may be placed. Thus, it is possible to provide multiple conjugate pupil planes. Any description showing the placement of an aberration correction plate at any number of conjugate pupil planes is understood to include any placement of an aberration correction plate at any number of conjugate pupil planes. It can be done.

[0084] FIG. 2 outlines a method for correcting aberrations in an optical system in accordance with one or more embodiments of the present disclosure. Schematically shown.

[0085] In step 202, the wavefront aberration of the optical system may be measured. For example, The wavefront is distorted by elements of the imaging optics of the system or by the design of the system. For example, referring to FIG. 1A, the imaging The optical element 104 may distort the wavefront 108 (see distorted wavefront 112a). ). Furthermore, in this case, the distorted wavefront 112a (i.e., wavefront aberration) can be measured. For example, in optical systems in the ultraviolet to visible wavelength range, aberrations are In another example, in an EUV actinic system, the aberrations can be measured using , can be determined using a phase-shifting point diffraction interferometer, further described by Patrick P. Naul Leau et al., Applied Optics, Volume 38, Issue 35, December 10, 1999 Extreme-ultraviolet phase-shifting po int-diffraction interferometer:a wave-fr ont metrology tool with subangstrom refe "Transmission-wave accuracy," which is incorporated by reference in its entirety. In addition, to determine aberrations in EUV-type systems, Some examples of this are US Patent No. 5,929,493 issued May 10, 2016 to Zhang et al. No. 9,335,206, which is incorporated herein by reference in its entirety. will be done.

[0086] In an optional step, the method 200 may further include filtering the measured wavefront aberrations into linearly independent aberration terms. For example, the method 200 may include fitting the measured wavefront aberration 112b to linearly independent Zernike polynomials or terms.

[0087] Step 204 includes at least partially correcting two or more aberration terms. two or more aberration correction plates 110 (for example, aberration correction plate 110a and aberration correction plate 110b) For example, a first aberration term of the plurality of aberration terms may be at least partially corrected. A first aberration correction plate 110a may be provided that is configured to correct multiple aberrations. Each of the terms is linearly independent of the others and can be configured to characterize a type of aberration. For example, each of the multiple aberration terms may represent the type of aberration as a function of the measured wavefront aberration (e.g., Figure 1 Further, in the above example, Each of the one or more aberration terms may characterize a different type of aberration of optical system 100. .

[0088] In one example, a first type of aberration of a first aberration correction plate of the two or more aberration correction plates, and and the second type of aberration of the second aberration corrector plate of the two or more aberration corrector plates is astigmatism, It can be one of coma, spherical aberration, or trefoil aberration. a first type of aberration of a first aberration correction plate among the above aberration correction plates, and two or more aberrations The second type of aberration of the second one of the corrector plates is any aberration including higher order Zernike terms. can be one of the Zernike terms of

[0089] One example of providing the aberration correction plate 110 (e.g., the first aberration plate 110a) is a two-Zernier aberration correction plate. Zernike terms are at least partially aberrated simultaneously on the same plate if the Zernike terms are of the same aberration type. For example, the Zernike 5 term (Z5) and the Zernike 6 term (Z6) may be corrected as follows: It may be associated with astigmatism, and it is desirable for the aberration correction plate 110 to correct the astigmatism. Any combination of Z5 and Z6 is equal to the square root of the sum of the squares, RSS, of Z5 and Z6. The wavefront of Z5 can have a different amplitude, but is determined by the Zernike coefficients of Z5 and Z6. This is the Zernike 7th and 8th terms (Z7 and Z8 respectively) and the Zernike The same can be said for Nike 10 and 11 (Z10 and Z11, respectively). Using such properties, we can define two Zernike terms associated with the same type of aberration as A corrective aberration correction plate 110 may be provided.

[0090] For example, in FIG. 3A, an astigmatic wavefront 300 having an astigmatic wavefront aberration type of Z5 is The color of the astigmatic wavefront 300 (e.g., the shade of gray used) corresponds to the wavefront aberration level. corresponds to a color where mid-gray (as shown in the corner) indicates zero aberration. The astigmatism correction plate 110 has a 2 If we have a thickness profile of 3D on a uniform substrate of constant thickness, we obtain an astigmatic wavefront of 3D. 00, where w(x,y) is the 2D is the wavefront phase function, and n is the refractive index of the plate material. This means that the positive phase (longer path length and This can mean that the thickness decreases with increasing thickness (defined as These properties may also be applied to other aberration terms (e.g., Z7 and Z8, and Z10 and Z11). When such an astigmatism correction plate is provided, the Zernie projection in the XYZ coordinates is The Zernike 5 term (Z5) and the Zernike 6 term (Z6) may follow a sine function.

[0091]

number

[0092] where θ is the rotation angle around the Z axis in Figure 3A, measured from 0 to π, and Z50 is the angle of the correction plate is the amplitude of

[0093] An illustration of the above example can be seen in Figures 4A and 4B. Figure 4A shows Z5 402 and Figure 4 shows an example of Z6 404. When the astigmatism correction plate is rotated as described above, the sine wave The projections for the rotation angles Z5 402 and Z6 404 are generated. In a 2D plane with horizontal axis Z5 and vertical axis Z6, the coordinates of the system of FIGS. 4A and 4B The measured system astigmatism Z5 is -32.7 mWave. The specified Z6 is 12.48mWave. Furthermore, the RSS is 35mWave. The Z5 amplitude of the astigmatism correction plate is 35 mW (the maximum height of Z5 402 in Figure 4A). In this case, the azimuth angle φ (for example, in the range 0 to 2π) is 159.09 degrees, and the projected Z5 and Z6 are 32.7 degrees (shown by point 406 on Z5). ) and -12.48 (shown by point 408 in Z6) (i.e., these are (This is the opposite of system astigmatism and cancellation system astigmatism.) In general, the azimuthal angle φ If is in the range of 0 to π, the correction rotation angle (e.g., the aberration around the optical axis of the optical system) The rotation angle of the correction plate is θ = (φ + π) / 2, and when the azimuth angle φ is in the range of π to 2π, The correction rotation angle is θ=(φ-π) / 2. In this case, the rotation angle of the aberration correction plate is (159 0.09+180) / 2=169.55 degrees (2.96 rad), the system Astigmatism Z5 and Z6 are completely corrected by an astigmatism correction plate with an amplitude of 35 mWave. This example shows that system astigmatism, at least in some embodiments, is The amplitude of the astigmatism correction plate 110 is such that both the Z5 and Z6 terms of astigmatism (i.e., system It can be corrected when the RSS of the astigmatism is equal to the RSS of the astigmatism.

[0094] However, if the Z5 amplitude of the astigmatism correction plate is not the same as the RSS of the system astigmatism, the residual There may be residual astigmatism due to incomplete correction. Referring to the example mentioned above, the system astigmatism RSS value is in the range of 10 to 100 mWave. The astigmatism correction plate in the library with 20mWave intervals is theoretically Note that you should not have an astigmatism correction plate greater than 10 mW. Regarding Fig. 4B, the correction by the astigmatism correction plate with 10 mWave and 5 degrees rotation angle error is shown. The simulation of the residual astigmatism RSS value after correction is shown.

[0095] The residual astigmatism in FIG. 4B can be expressed by the following function:

[0096]

number

[0097] Here, A sis the system astigmatism, φ s is the azimuth angle in the Z5Z6 plane, A c is astigmatism correction Z5 amplitude of the plate, θ is the rotation angle, and Δ A is the residual astigmatism R after correction by the astigmatism correction plate Theoretically, to completely correct astigmatism, A c =A s and cos(2θ-φ s )=-1. c ≠A s In some embodiments, minimal residual astigmatism is The rotation angle θ that gives the difference is the function cos(2θ-φ s )=-1, so that the above equation Section 2, 2A of s A c (1+cos(2θ-φ s )) is equal to zero.

[0098] Similar to the above examples and examples associated with astigmatism, coma (i.e., Z7 and Aberration correction plates associated with Z8) and trefoil aberrations (i.e., Z10 and Z11) 110 may be similarly provided and / or have similar characteristics. For example, the coma In the case of trefoil aberration, the required rotation range is 0 to 2π. For example, using the RSS of Z7 and Z8, the The amplitude of the aberration correction plate 110 can be determined by the angle of the aberration correction plate 110. may similarly be determined based on the Zernike coefficients of the associated Zernike terms.

[0099] For example, similar to the example described above for Z5 and Z6, an aberration correction plate for coma aberration can be used. The provision can be similar to the provision of an aberration correction plate for astigmatism described above. For example, in the case of coma, Z7 and Z8 projected in the XYZ coordinates follow a sine function: obtain.

[0100]

number

[0101] where θ is the rotation angle around the Z axis in Figure 3B, measured from 0 to 2π, and Z is the correction is the amplitude of the plate.

[0102] An illustration of the above example can be seen in Figures 5A and 5B. Figure 5A shows the Z7 502 and The figure shows an example of Z8 504. When the coma compensator plate is rotated as described above, the sine wave The projections for the rotation angles Z7 502 and Z8 504 are generated. In a 2D plane with horizontal axis Z7 and vertical axis Z8, the coordinates of the system of FIGS. 5A and 5B are The measured system coma Z7 is -27.46mWave, The measured Z8 is 21.7mWave. Furthermore, the RSS is 35mWave. The amplitude of Z7 of the aberration correction plate is 35 mW (the maximum height of Z7 502 in Figure 5A). In this case, the azimuth angle φ (for example, in the range 0 to 2π) is 141.68 degrees, and the projected Z7 and Z8 are 27.46 degrees (shown by point 606 on Z7). ) and -21.7 (shown by point 508 in Z8) (i.e., these are (This is the opposite of system coma and cancellation system coma.) Generally, the azimuthal angle φ If is in the range of 0 to π, the correction rotation angle (e.g., the aberration around the optical axis of the optical system) The rotation angle of the correction plate is θ = φ + π, and when the azimuth angle φ is in the range of π to 2π, the correction rotation The angle is θ=φ-π. In this case (Fig. 5A), the rotation angle of the aberration correction plate is 141.68 + When rotated to 180 = 321.68 degrees (5.61 rad), the system coma aberration of Z7 and Z8 is fully corrected by a coma corrector with an amplitude of 35 mW. The coma correction plate for Z7 is, at least in some embodiments, The amplitude of 110 is the RS of both the Z7 and Z8 terms of coma (i.e., system coma). If it is equal to S, it indicates that it can be corrected.

[0103] However, if the Z7 amplitude of the coma compensator is not the same as the RSS of the system coma, There may be residual coma due to incomplete correction. Referring to the above example, the system coma RSS value is in the range of 10 to 100 mW. The coma aberration correction plate in the library with 20mWave intervals is theoretically ideal. Note that the coma correction plate should not exceed 10 mW. In this regard, FIG. 5B shows the results for a coma correction plate with a 10 mW and a 5 degree rotation angle error. 1 shows a simulation of the residual coma aberration RSS value after correction by the

[0104] The residual coma in FIG. 5B can be expressed by the following function:

[0105]

number

[0106] Here, C s is the system coma, ψ s is the azimuth angle of the Z7Z8 plane, C c is the Z value of the coma aberration correction plate 7 is the amplitude, θ is the rotation angle, and Δ Cis the RSS of the residual coma after correction. To fully compensate for the difference, C c =C s and cos(θ-ψ s )=-1. C c ≠ C s In some embodiments, the rotation angle θ that provides the minimum residual coma is given by the function co s(θ-ψ s ) = -1, and as a result, the second term of the above equation, 2C s C c (1+co s(θ-ψ s )) is equal to zero.

[0107] In another example, for trefoil aberration, Z10 and Z2 are projected in the XYZ coordinates. 11 may follow a sine function.

[0108]

number

[0109] where θ is the rotation angle around the Z axis, measured from 0 to (2 / 3)π, and Z100 is the offset. is the amplitude of the positive plate.

[0110] By using quartz material and IBF technology, a thin (e.g., 0.5 mm thick) Z5 The purity of the Zernike terms in the aberration correction plate 110 can be very high. The amplitude can be as small as 1 mWave.

[0111] In FIG. 3B, a coma wavefront 302 having a coma wavefront aberration type of Z9 is shown in FIG. Indicated by purpose.

[0112] By using quartz or fused silica materials and IBF technology, thin (e.g., 0.05 mm thick) The Zernike term purity of the Z7 aberration correction plate 110 can be very high. The amplitude of the Zernike terms can be as small as 1 mWave.

[0113] In FIG. 3C, the Zernike 9-term (Z9) spherical aberration wavefront aberration type, which may be rotationally symmetric, For illustrative purposes, a spherically aberrated wavefront 304 having Z In the case of the 9 aberration correction plate 110, there is no need to rotate the plate.

[0114] In an optional step (not shown), at least one of the two or more aberration correction plates is For example, the optical system or imaging tool may be configured to correct for apodization. One or more aberration correction plates 110 in the lens 122 may be used for apodization (e.g., to correct for non-uniform pupil intensity). For example, the aberration correction plate 110 may be configured to correct the aberration distribution. The corrector plate 110 (e.g., the aberration correction plate 110a in FIG. 1A) improves the uniformity of the pupil transmission of the optical system. a coating (on the first surface (not shown) or the second surface of the aberration correction plate 110) that can improve (not shown) on at least one of the In this regard, the coating of the aberration correction plate may be formed by applying a coating of aberration correction plate having a thickness of 1000 nm or less near the center of the aberration correction plate. For example, the light may be configured to reduce pupil transmission by a value (e.g., 10% lower). Each aberration correction plate in the optical system 100 (e.g., the imaging tool 122) may be apodized. (i.e., apodization coating) The advantage of one or more correctors that correct both apodization and aberrations is that Another example is an optical system that corrects both apodization and aberrations. The orientation may be rotationally symmetric. Please note that is for illustrative purposes only.

[0115] Although apodization is not the same as aberration, in at least some embodiments, Note that any of the aberration correction plates mentioned above may instead be apodization correction plates. For example, any aberration correction plate will correct apodization, but not any convergence. It may be an apodization plate that does not correct the difference term. For example, the aberration correction plate 1 in FIG. 10a or the aberration correction plate 118a of FIG. 1B may be an apodization correction plate, Corrects apodization but does not correct any aberration terms. The catalog of corrector plates 114 is a catalog of aberration and apodization corrector plates, or apodization plates. In this regard, the set 116a may be a catalog of only the calibration correction plates. set 116b may be a set of differential correction plates 118, and set 116b may be a set of apodization correction plates. set 116a corrects aberration terms and set 116b corrects apodization terms. Alternatively, or in addition to the above, any convergence The aberration corrector may be an aberration and apodization corrector. For example, set 116a includes aberration and apodization correction plates. There can be a set of 118.

[0116] Referring back to FIG. 2, in optional step 206, two or more aberration correction plates are For example, referring to FIG. 1A, the first aberration correction plate 110a and The first and second aberration correction plates 110a and 110b may be two or more aberration correction plates, and the optical system 1 00 or the imaging tool 122. For example, the first aberration correction plate 110a and A second aberration correction plate 110b can be inserted in a pupil plane (not shown) of the system 100. Regarding the optical system 100, it may have one or more pupil planes and one or more aberration correction plates. 110 may be inserted into one or more pupil planes of the optical system 100. For example, two or more Of the aberration correction plates 110, one or two aberration correction plates 110 may be inserted on each pupil plane. In another example, each of the aberration correction plates 110 of all the aberration correction plates 110 may be a 100. For example, a non-rotationally symmetric aberration correction plate 110 (astigmatism) Such an aberration corrector 11 may include an aberration corrector associated with aberration or coma. 0, at a rotation angle configured to at least partially correct the associated aberration term, In another example, the aberration correction plate 110 may be inserted in the optical axis of the optical system 100. (which may include an aberration correction plate associated with spherical aberration) is attached to the optical axis of the optical system 100, It can be inserted at any rotation angle relative to the optical axis.

[0117] All methods described herein may be used to record the results of one or more steps of the method embodiments. The results may include any of the results described herein. The memory may be stored in any manner known in the art. For example, memory 156), or any other suitable storage medium known in the art. After the results are stored, they are accessed in memory and processed in the manner described herein. or system embodiment to display to the user. may be integrated into another software module, method, or system, etc. Furthermore, results may be stored "permanently," "semi-permanently," "temporarily," or for a certain period of time. For example, the memory may be random access memory (RAM), and the result is always It does not need to persist in memory indefinitely.

[0118] Each of the method embodiments described above may be used in conjunction with any other method(s) described herein. It is further contemplated that the method may include any other step(s) of the method described above. Each of the described method embodiments may be implemented using any of the systems described herein (e.g., , the controller 152 of the imaging tool 122).

[0119] Those skilled in the art will recognize and appreciate the components, operations, devices, objects, and associated processes described herein. The explanations are used as examples to clarify the concepts, and various modifications of the configuration are contemplated. Therefore, as used herein, the specific implementations described The examples and accompanying discussion are intended to be representative of their more general classification. The use of a particular example is intended to represent that classification and does not necessarily imply specific components, operations, data, or the like. The term "device" should not be considered limiting unless it includes devices, vises, and objects.

[0120] As used herein, "top," "bottom," "front," and "rear" , "over", "under", "upper", "upward", "downward" Directional terms such as "upper," "lower," and "down" are used for illustrative purposes only. It is intended to provide a relative position, not to specify an absolute frame of reference. Various modifications to the described embodiments will be apparent to those skilled in the art. The general principles defined herein may be applied to other embodiments.

[0121] With respect to the use of virtually any plural and / or singular term herein, The person may convert from plural to singular and / or from singular to plural as appropriate to the context and / or use. The various singular / plural permutations are used herein for the sake of clarity. is not explicitly stated.

[0122] The subject matter described herein may be contained within or connected to other components. Such depicted architectures are for illustrative purposes only. and in fact it is understood that many other architectures that achieve the same functionality can be implemented. In a conceptual sense, it is any arrangement of components to achieve the same functionality. The devices are effectively "associated" to achieve a desired function. Any two components herein that are combined to achieve the above are considered to be "associated" with each other. The desired functionality can be considered to be "defined" in the architecture or intermediate structure. Similarly, any two components so related are realized They can also be considered to be "connected" or "coupled" to each other to achieve a desired function. and any two components that may be so related are "connected" to each other. Specific examples of combinability include the following: components that are not physically matable and / or physically interacting with one another; and and / or wirelessly interactable and / or wirelessly interacting components and / or logic It includes components that interact logically and / or are logically capable of interacting.

[0123] It should further be understood that the present invention is defined by the appended claims. Generally, the following statements are made in this specification, particularly in the appended claims (e.g., It should be noted that the terms used in this document are generally intended as "open" terms. It will be understood by those skilled in the art (for example, the term "including" "including but not limited to" and "having" The term "has at least" should be interpreted as "having at least" and the term "includes" should be interpreted as "having at least" and "having at least ... (e.g., the term "including but not limited to" should be interpreted as "including but not limited to"). If a claim recitation is intended, such intention is not and in the absence of such a statement, no such intention exists. It will be further understood by those skilled in the art that, for example, the following attachments may be used to aid in understanding: The claims include the use of the introductory phrases "at least one" and "one or more" to clarify the claim description. However, the use of such phrases is prohibited by the indefinite article "a" or "an" " the introduction of a claim recitation by " shall not affect any particular shall not be construed as meaning to limit the claims to inventions containing only one such recitation. should not be used even if the same claim is indefinitely defined with the introductory phrase "one or more" or "at least one." The article "a" or "an" (e.g., "a" and / or "an" usually means "at least one" " or "one or more." and the same applies to the use of definite articles used to introduce claim recitations. In addition, even if a specific number of claims is explicitly stated, Merchants should generally interpret such statements to mean at least the number stated. (For example, a statement of "two statements" without any other qualifiers is (Usually means at least two descriptions, or more than two descriptions.) Furthermore, "A, B and C" In instances where phrases similar to "at least one of, etc." are used, it is generally understood that Such constructions are intended in the sense that one of ordinary skill in the art would understand the term (e.g., "A , B and C” includes, but is not limited to, only A, B only, C only, A and B together, A and C together, B and C together, and / or A and B and C together, etc.) "at least one of A, B, or C, etc." In instances where a term similar to "is used," such a construction is generally understood by those skilled in the art to be a The meaning that the term is intended to be understood (e.g., "at least one of A, B, or C"). "Systems having one of these" includes, but is not limited to, A only, B only, C only, A and B A system having A and C together, B and C together, and / or A, B, and C together Virtually any disjunctive word and / or phrase that represents two or more alternative terms is In the specification, claims or drawings, one of the terms, either of the terms, or both terms It will be further understood by those skilled in the art that the present invention should be understood to take into account the possibility of including For example, the phrase "A or B" includes the possibilities of "A" or "B" or "A and B." It will be understood that:

[0124] It is believed that the present disclosure and many of its attendant advantages will be understood from the foregoing description. without departing from the subject matter shown or sacrificing all of its important advantages. It will be apparent that various changes in form, construction and arrangement of the components may be made. The forms shown are merely illustrative and it is the intent of the following claims to encompass and include such modifications. It is further understood that the present invention is defined by the appended claims. It should be understood.

Claims

1. 1. A system with aberration correction, comprising:

1. An optical system with aberration correction, comprising: illumination source, a detector, and an optical system including one or more collection optics configured to image the sample onto the detector based on illumination from the illumination source; A catalog of aberration correction plates, Two or more sets, each set of the two or more sets comprising: a catalog including two or more sets, each set correcting a different specific linearly independent aberration term, the two or more sets including two or more aberration correction plates that provide at least partial correction of specific linearly independent aberration terms, wherein any particular one of the two or more aberration correction plates has a spatially varying thickness profile that provides a selected amount of correction for the particular linearly independent aberration term of the two or more linearly independent aberration terms; Equipped with where: the optical system includes a selected combination of two or more aberration correction plates to at least partially correct aberrations within selected tolerances; each aberration correction plate of the selected combination is an aberration correction plate of one of the two or more sets; system.

2. The system of claim 1 , wherein the catalog further includes an apodization set configured to at least partially correct apodization, and the selected combination includes an apodization correction plate of the apodization set.

3. The system of claim 1 , wherein at least one aberration correction plate of the selected combination is configured to at least partially correct apodization.

4. 2. The system of claim 1, wherein the at least one aberration correction plate is configured to at least partially correct apodization because the at least one aberration correction plate comprises an apodization coating configured to radially vary transmittance according to a radial variation function of a state in which transmittance from a center of a pupil of the optical system increases with respect to an outer edge of the pupil when the at least one aberration correction plate is positioned in a pupil plane of the optical system.

5. The system of claim 1 , wherein the selected combination is adjustable to provide different configurations of the optical system.

6. The system of claim 1 , wherein the optical system is an imaging tool.

7. The system of claim 1 , wherein the two or more linearly independent aberration terms include astigmatism.

8. The system of claim 1 , wherein the two or more linearly independent aberration terms include coma.

9. 1. A method for correcting aberrations in an optical system, comprising: determining the wavefront aberration of the optical system; and providing two or more aberration correction plates for the optical system, each of the two or more aberration correction plates configured to at least partially correct one aberration term of a plurality of aberration terms, each of the plurality of aberration terms being linearly independent of one another and configured to characterize a type of aberration, each aberration term characterizing a type of aberration of the optical system and based on the determined wavefront aberration; A method comprising:

10. The method of claim 9 , wherein at least one aberration correction plate of the two or more aberration correction plates is configured to at least partially correct apodization.

11. 10. The method of claim 9, wherein the at least one aberration correction plate is configured to at least partially correct apodization because the at least one aberration correction plate comprises an apodization coating configured to radially vary transmittance according to a radial variation function of increasing transmittance from the center of a pupil of the optical system to the outer edges of the pupil when the at least one aberration correction plate is positioned in a pupil plane of the optical system.

12. The method of claim 9 , wherein the determining comprises measuring the wavefront aberration of the optical system.

13. The method of claim 9 , wherein the determining comprises simulating the wavefront aberrations of the optical system.

14. The method of claim 9 , wherein each of the plurality of aberration terms is a Zernike term.

15. The method of claim 9 , wherein the plurality of aberration terms includes at least one of astigmatism, coma, spherical aberration, or trefoil aberration.

16. 10. The method of claim 9, wherein the first type of aberration of a first of the two or more aberration corrector plates is one of astigmatism, coma, spherical aberration, or trefoil aberration.

17. 17. The method of claim 16, wherein the second type of aberration of a second aberration corrector plate of the two or more aberration corrector plates is one of astigmatism, coma, spherical aberration, or trefoil aberration.

18. the first type of aberration of the first aberration correction plate is astigmatism; wherein the amplitude of the first aberration correction plate is based on the square root of the sum of the squares of a Zernike 5 term of astigmatism and a Zernike 6 term of astigmatism that are based on the determined wavefront aberration of the optical system, such that the first aberration correction plate is configured to at least partially correct both the Zernike 5 term and the Zernike 6 term when positioned in a pupil plane of the optical system and rotated to coincide with a direction of the first type of aberration of the optical system.

18. The method of claim 17.

19. the second type of aberration of the second aberration correction plate is coma; wherein the amplitude of the second aberration correction plate is based on the root-sum-square of a Zernike 7 term of coma and a Zernike 8 term of coma that are based on the determined wavefront aberration of the optical system, such that the second aberration correction plate is configured to at least partially correct both the Zernike 7 term and the Zernike 8 term when positioned in a pupil plane of the optical system and rotated to coincide with a direction of the second type of aberration of the optical system.

18. The method of claim 17.

20. The method of claim 9 , wherein the optical system is an imaging tool.

21. The method of claim 9 , wherein the method further comprises providing an apodization correction plate configured to at least partially correct for apodization.

22. 1. An optical system with aberration correction, comprising: illumination source, detector, one or more collection optics configured to image the sample onto the detector based on illumination from the illumination source; and one or more aberration correction plates located at one or more pupil planes of the one or more focusing optical elements, the one or more aberration correction plates providing at least partial correction of one or more linearly independent aberration terms, wherein any particular one of the one or more aberration correction plates has a spatially varying thickness profile and provides a selected amount of correction for a single particular aberration term of the one or more linearly independent aberration terms; wherein the one or more aberration correction plates include a first aberration correction plate configured to at least partially correct a first aberration term characterizing a first type of aberration, wherein the first type of aberration is one of astigmatism, coma, or trefoil aberration; wherein any aberration correction plate containing aberration terms characterizing astigmatism, coma, or trefoil aberration types is configured to be rotated to align with the orientation of said aberration type of said optical system. Optical system.

23. 1. A system with aberration correction, comprising:

1. An optical system with aberration correction, comprising: illumination source, a detector, and an optical system including one or more collection optics configured to image the sample onto the detector based on illumination from the illumination source; A catalog of aberration correction plates, one or more sets, each set of the one or more sets comprising: one or more aberration correction plates that provide at least partial correction of specific linearly independent aberration terms, wherein any particular one of said one or more aberration correction plates has a spatially varying thickness profile that provides a selected amount of correction for said particular linearly independent aberration term of the one or more linearly independent aberration terms, each set correcting a different specific linearly independent aberration term; wherein each particular linearly independent aberration term characterizes a type of aberration among one or more types of aberration, and wherein each type of aberration among the one or more types of aberration is one of astigmatism, coma, or trefoil aberration. one or more sets; Equipped with where: the optical system includes a selected combination of one or more aberration correction plates to at least partially correct aberrations within selected tolerances; each aberration correction plate of the selected combination is an aberration correction plate of the one or more sets; wherein any aberration correction plate containing aberration terms characterizing astigmatism, coma, or trefoil aberration types is configured to be rotated to align with the orientation of said aberration type of said optical system. system.

24. 1. A method for correcting aberrations in an optical system, comprising: determining the wavefront aberration of the optical system; and providing one or more aberration correction plates for the optical system, each of the one or more aberration correction plates configured to at least partially correct one of one or more aberration terms, each of the one or more aberration terms being linearly independent of one another and configured to characterize a type of aberration, each aberration term characterizing a type of aberration of the optical system and based on the determined wavefront aberration; Including, wherein the one or more aberration correction plates include a first aberration correction plate configured to at least partially correct a first aberration term, the first aberration term characterizing a first type of aberration, wherein the first type of aberration is one of astigmatism, coma, or trefoil aberration; wherein any aberration correction plate containing aberration terms characterizing astigmatism, coma, or trefoil aberration types is configured to be rotated to align with the orientation of said aberration type of said optical system. method.

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