Soft x-ray monochromator

Abstract

A soft X-ray monochromator that includes a substrate that comprises a polished curved surface; and one or more platelets having one or more corresponding polished surfaces that are optically bonded to the polished curved surface; wherein the one or more platelets are bent to follow a curvature of the polished curved surface.

Description

SOFT X-RAY MONOCHROMATORCROSS REFERENCE

[0001] This application claims priority of US provisional patent serial number 63 / 619,293, filing date January 9, 2024 which is incorporated herein in its entirety. BACKGROUND OF THE INVENTION

[0002] Metrology for semiconductor process control using soft X-ray (having wavelengths that range between 0.025 - 10 KeV). Metrology for semiconductor process control to carefully control the film composition and thickness, dopant level, impurities, critical dimensions, nanostructures, surface roughness and potential defect levels in order to optimize the semiconductor manufacturing process. This includes but not limited to X- ray reflectivity X-ray scatterometry, XPS, XRF, Ptychography, etc.

[0003] Advanced semiconductor metrology requires a small spot size (50 um or less) with no more than a couple of percent scatter outside the measurement spot (depending on X-ray wavelength). Any X-ray outside the measurement area leads to signal contamination from structures outside the intended measurement box.

[0004] There is a growing need to provide a cost-effective solution for focusing soft x- ray beams.

[0005] SUMMARY

[0006] A soft X-ray monochromator as illustrated in the application.

[0007] A method for manufacturing a soft X-ray monochromator as illustrated in the application.

[0008] A method for using a soft X-ray monochromator as illustrated in the application.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 illustrates an example of x-ray beam focusing from a finite x-ray source via an ellipsoidal or toroidal monochromator; and

[0010] FIG. 2 illustrates an example of design parameters for a focusing ellipsoid monochromator;

[0011] FIG. 3 illustrates an example of a design parameters;

[0012] FIGs. 4-5 illustrate examples of a monochromators;

[0013] FIGs 6-7 illustrate examples of methods; and

[0014] FIG. 8 is an example of a table.DETAILED DESCRIPTION OF THE DRAWINGS

[0015] For soft X-rays, reflective optics with high focusing efficiency and little to no chromatic aberration are desired. Preserving brightness and having a well-defined spot with minimal scatter outside the defined spot size requires very low surface roughness and low slope errors.

[0016] X-ray focusing mirrors with high performance in the soft X-ray region are technically challenging and expensive. Designing a system with the ability to focus a beam size to 50 um or less for X-ray energy of less than 10 keV requires a large numerical aperture. The high numerical aperture implies very high curvature. The existing multilayer mirror state of art requires a substrate with excellent conformance to an ideal shape over length scales down to approximately the wavelength of the reflected radiation. This is difficult to achieve in optical fabrication. Attaining smoothness while retaining slope and figure errors is most easily achieved on flat surfaces and is progressively more difficult as the required surface shape reduces in symmetry. At wavelengths <100nm, poor smoothness causes excessive scattered light. Ultra-precise figure shape is required for mirrors to control coherent wavefronts while suppressing unwanted speckles. Depending on the soft X-ray wavelength, the surface roughness is typically 0.2nm or below to prevent unwanted scatter light outside the measurement spot. Surface roughness and ultra-precise figure shape is a critical parameter and involves advanced manufacturing technology to achieve very low roughness compatible with x- ray optics. The ability to maintain surface quality while correcting figure is key.

[0017] There are many technical challenges in the fabrication and in the measurement to verify the quality. This is a problem for both mirrors and for spectrometers / monochromators .

[0018] The most common x-ray energy utilized in XPS is AlKa (1486.7eV) which is typically transported and focused onto a wafer surface via a monochromator to narrow the natural line width of the emission line for chemical state identification.

[0019] Photoelectrons generated by AlKa radiation will have a kinetic maximum energy of ~1486.7eV, thus limiting the analysis depth to ~ lOnm and providing a limited range of secondary x-ray fluorescence lines which can be detected simultaneously and used asindependent and complementary input parameters for the total dose of the analyzed material.

[0020] The most used focusing and monochromator system consists of an ellipsoidal or toroidal substrate (see figure 1) that is populated with quartz (100) crystal platelets and provides point-to point focus of the target emission to the sample surface with an energy bandwidth ~0.5eV. Figure 1 illustrates a wafer 13 illuminated with a focused monochromatic soft X-ray beam 23 from monochromator 12 that receives an input x-ray beam 22 emitted from anode 11 when illuminated with a micro-focused e-beam 21.

[0021] The advantage of these systems is that monochromators with large angular acceptance and thus high transport efficiency can be manufactured. A monochromator focusing system of this type may also transport when optimized for the 1storder Bragg diffraction for AlKa can also focus discrete higher order diffraction orders (energies) according to nX^2d sin(O) (d is the crystal lattice spacing) to the wafer surface. However, the coverage of focusable energies is discrete by nature and intermediate energies other than n . equivalent can, by design, not be transported to the sampling area. Lower x-ray energies are not accessible or focusable at the sample surface with such a monochromator and would require a larger 2d lattice spacing applied to the substrate.

[0022] Methods for focusing monochromatic x-ray beams of multiple but selectable energies from 0.025 keV to 10 keV onto a wafer surface will be described.

[0023] Ellipsoidal and Toroidal mirrors fabricated with slope errors of less than 1 arc sec and with low surface roughness of less than 0.2 nm, offer low aberrations and enable soft X-ray focusing with high precision. The high NA (Numerical Aperture) leads to difficulties in the fabrication and measurement of the surface roughness of a soft X-ray mirror. These technical difficulties make the mirror very expensive.

[0024] Figure 2 is an example of requirements for a focusing ellipsoid - illustrated in relation to the Rowland Circle 99. The geometry would be described according to x2 / a2+y2 / b2+ z2 / b2=1. The choice of the half conjugate distance c and would be instrument geometry dependent but the ratio c / b and its tolerance has to be matched to the Bragg angle and rocking curve of the crystal and the admitted x-ray line width.

[0025] For example, c / b may equal to tan(9O-0Bragg), ©Bragg being the Bragg angle of the crystal of the platelets.

[0026] A realistic manufacturing will require tolerances for the substrate shape, i.e.: C = C + / - C tolerance, therefor c / b = (c / b) + / -(c / b)toierance.

[0027] For example, b / a tolerances are determined generating intersection lines of b / a (see also figure 3), assuming the extremes of: a. C+Ctoierance and C-Ctoierance for nominal c / b b. And similarly extremes of: (c / b) + (c / b)toierance and(c / b) - (c / b)toierance for the design value of “c”.

[0028] The region where the four lines intersect determine the ellipsoid figure tolerance.

[0029] In general, the b / a tolerance will have the smallest permissible error.

[0030] Embodiments of the present invention pertain to methods and systems for fabricating platelets and bonding to Ellipsoid, Toroidal or other types of mirrors for focusing soft X-rays having energies from 0.025 keV to 10 keV. We will refer to this energy range as Soft X-rays.

[0031] Flat thin Platelets can be polished to the desired surface roughness and can be incorporated and placed conformal to Ellipsoidal and Toroidal mirrors. Flat thin platelets can be thinned down to less than 120 um (or even less than lOOum) to be able to be bent to be conformal to the optical substrate. The platelets can then be bonded to the curved optical substrate. We will refer to these optics as optical backings or substrates. The bonded side of the platelet has flatness and smoothness like the substrate surface at length scales >lum. The reflecting side is flat and smooth at length scales down to approximately the wavelength of the reflected radiation. The surface roughness of the reflecting side needs to be less than 0.5 nm for wavelengths in the 0.8-10 keV. For wavelengths 0.025 keV to 0.8 keV, surface roughness of the reflecting side needs to be less than 0.2 nm. Normally the platelet would have parallel faces, but platelet thickness could be varied slightly to allow correcting e.g., a toroid to ellipsoidal shape.

[0032] The substrate can be cylindrical, spherical, toroidal, ellipsoidal, log spiral, sinusoidal spiral, or arbitrary shape. The substrate surface can be curved in either one or two dimensions. At length scales <lum, the substrate may substantially deviate from ideal in figure, slope error, or smoothness.

[0033] A monochromator composed of a thin platelet crystal, or a plurality of thin platelet crystals arranged in an adjacent array configuration on a substrate (fig 2) to occupy the optical field of view of interest provides point-to-point focus of the target emission to the sample surface with a narrow energy bandwidth on the order of ~0.5eV. The advantage of these systems is that monochromators with large angular acceptance and thus high transport efficiency can be manufactured, provided that absolute and relative pointing errors of crystal platelets is well controlled, ideally within 1 arc second or less to minimize focus distortions.

[0034] Figure 4 illustrates a monochromator 30 composed of a thin platelet crystal, or a plurality of thin platelet crystals (denoted 41, 42, 43 and 44) arranged in an adjacent array configuration on a substrate. The number of platelets can be 1 or a plurality of thin platelets to cover the optical field of view of interest. The platelets are optically bonded on polished curved surface 32 of a substrate or base 31.

[0035] The polished curved surface defines the shape of a curved mirror that includes the one or more platelets that interact with soft X-ray.

[0036] Figure 5 illustrates example of a cross sectional view of monochromators: a. First monochromator 30 A includes base 31 and a single platelet 45. b. Second monochromator 30B includes base 31, and two spaced apart platelets 46 and 47. c. Third monochromator 30C includes base 31, single platelet 45 and coating 51.

[0037] The top part of the substrate and bottom platelet surfaces need to be polished to no more than a few Angstrom each for proper optical bonding to occur. It is preferred that each surface is polished to 0.5nm or less for high-strength bonding to occur. For surfaces with greater than 0.5 nm RMS, bonding strength will begin to decrease rapidly.

[0038] Crystals (Bragg reflectors)

[0039] For the higher energy soft x-rays (~1 keV and above), crystals can be used as Bragg reflectors. In general, monochromator crystals for the higher energy range require smaller 2d lattice spacing and are quite readily available using various crystal plane orientations in crystals. These crystals can be thin down and bent to be conformal to the substrate and focus monochromatic x-rays on the sampling metrology region. Thin platelet crystals +ellipsoid or Toroidal substrates provide a monochromatic x-ray beam that is focusable on to a wafer substrate.

[0040] Examples: a. YB66 or Beryl monochromator crystals can be used for covering the soft X-ray region from up to 1.1 to 2 keV, Single crystal germanium platelets can be used to reflect 5.4 keV x-rays. b. Quartz can be used to reflect 1,4, 1.49 keV or 5.9 keV. c. Single crystal germanium platelets can be used to reflect 5.4 keV x-rays.

[0041] To provide a further example, for an assumed Bragg angle of 60degree, the focusing / monochromator system with fixed optics location and angle could be applicable for the following x-ray energies using selectable monochromator crystals at fixed height and angle as listed below in table 1 of figure 8.

[0042] Table 1 illustrates approximate transmitted and focusable x-ray energies for different monochromator crystals and multilayers at an assumed fixed Bragg angle of 60 degree with achromatic input and output optics.

[0043] For wavelengths 0.8-10 keV, the platelet can be fabricated from a crystalline material to allow Bragg reflection from the undeformed crystal planes near the reflecting surface. Crystals such as Quartz, Germanium, YB66, Beryl, and-or Magnesium Fluoride.

[0044] For wavelengths 0.025-0.8 keV, the thin platelets can be a material such as Silicon, Silicon carbide, Borosilicate glasses, Fused Silica, Sapphire, Calcium Fluoride, Magnesium Fluoride or Crystals such as Quartz, Germanium, YB66 or other crystals or any suitable material that can be bonded to be conformal to the optical substrate and then coated with Multilayer coating designed for desired reflective x-ray. For example, Silicon or Silicon carbide wafers can be thinned and polished to any custom thickness as thin as 10 microns thick and are available in standard tolerances, or as tight a thickness tolerance as + / - 1 micron and achieve high level optical surface finishes to be smaller than 10 Angstroms.

[0045] Multilayer (ME) mirror monochromators

[0046] Reflectivity can be enhanced by ME coating. Depending on the soft X-ray energy, ME coatings can be deposited on final optical assembly (Substrate-i- Platelet). Multilayer coatings can be designed and optimized for narrow wavelength reflection. Wavebands MEcoatings can reflect a narrow band with an engineered central wavelength, allowing the imaging of the desired X-ray with excellent spectral resolution For X-ray energies requiring 2d-lattice spacings larger than 27 A, natural crystals are no longer available with defined lattice structure and multilayer mirror monochromators are used. Multilayers can be deposited on ellipsoidal, toroidal, or other substrates. For example, an ellipsoidal substrate- to focus a monochromatic x-ray beam from the x-ray source to the sampling surface. A specific example may be use of a W / Ti multilayer with 1.4nm period and relative layer thickness of 0.55 having 300 repeating layers onto the substrate. For example, for an x-ray energy of 452.2eV (Ti La), maximum reflectivity ideally 25% occurs at a Bragg angle of 78.3 degrees (CXRO website). This engineered multilayer or Multilayers diffractors can be optimized for different x-ray energies by utilizing different material combinations, layer ratio and thickness, as well as number of layers on the substrate. This applies for WSi and CrTi multilayers.

[0047] Multilayer coatings can be designed and optimized for narrow wavelength reflection made of the following (but not limited): Molybdenum / Silicon (Mo / Si), Niobium / Silicon (Nb / Si), Ruthenium / Boron (Ru / B), Tungsten / Carbon (W / C), Platinum / Carbon (Pt / C), Nickle / Cobalt (Ni / Co), Chrome / Carbon Cr / C, Scandium / Carbon (Sc / C), Nickel / carbon (Ni / C), Molybdenum / carbon (Mo / C)

[0048] Bonding

[0049] Platelets can be optically bonded to substrates via multiple methods such as Adhesives, UV (Ultraviolet) activated adhesives, techniques used silicon-to silicon bonding or optical bonding. However, the preferred method is optical bonding. It is expected that bonded side of the platelet will experience local elastic or plastic deformation to conform to the asperities on the substrate or platelet surfaces. However, this deformation will be strongly attenuated as a function of platelet thickness, and the reflecting surface will exhibit its local smoothness while conforming to the substrate shape. One major disadvantage to other techniques is they cannot be adjusted after bonding. Plausibly bonding could be achieved with a low viscosity glue that is a couple of nm thick. In that case the glue would conform rather than the platelet.

[0050] Optical contact is typically performed to ensure that the bonded platelets or crystals strictly conform to the precision surface of the substrate (e.g., typically an elliptical or toroidal surface).

[0051] Direct optical bonding is a bonding technique that allows for a high strength joining of a variety of similar and dissimilar materials (including optical glasses, silicon, germanium, metals, and laser crystals) without introducing any intermediate layer. Adhesion is provided solely by intermolecular forces between the surfaces which should be planar, smooth, and clean. A smooth surface is a key factor for successful direct bonding.

[0052] Cleaning

[0053] The substrate should be thoroughly cleaned. Final cleaning steps should include a high purity de-ionized water rinse step prior to the contacting step.

[0054] Alternatively, oxygen plasma cleaning or UVO cleaning can be employed prior to the contacting step.

[0055] Cleaning and bonding should be carried out in a clean particle environment. Contacting can be performed in atmospheric clean room conditions to avoid particle contamination.

[0056] Thinning

[0057] Depending on the material, platelets can thin to less than -120 microns to handle any associated bend stress (e.g., stress from contacting them to a highly curved substrate). A number of platelets and materials are designed also to handle any associated bend stress and for ease of assembly and alignment.

[0058] Debonding

[0059] UV light can be used the platelets to be deboned enabling 1) realignment, 2) refurbish, 3) replaced damaged platelets. Wavelength below 450 nm down to the absorption edge of platelet material can be used. For example, Quartz has an absorption edge 9 eV (~ 138nm). In the case where Quartz platelets can be used, a UV light source that has wavelength 450 and below down to 140 nm can be used to debone and replace or realign platelets. UV sources can be (but not limited to any UV sources produced by a discharge plasma source, RF source or other. The plasma source could be N2, 02, Ar Kr, Ne, or any mixtures.

[0060] Platelet could have a printed, embossed, etched, etc. grating or Fresnel lens-like set of reflecting ridges. Presumably easier to fabricate while flat, and then bend to shape.

[0061] Ellipsoid, Toroidal, or other types of mirrors for focusing soft X-rays having energies from 0.8 keV to 10 keV. We will refer to this energy range as Soft X-rays

[0062] Benefits a. One major advantage is that this technology enables x-ray optics with large numerical aperture with high focusing efficiency. Easier to fabricate and lower cost. b. Ellipsoid, Toroidal, or other types of mirrors for focusing soft X-rays having energies from 0.025 keV to 10 keV. c. Thin platelets can attain smoothness while retaining slope and figure errors is most easily achieved on flat surfaces and is progressively more difficult as the required surface shape reduces in symmetry. At wavelengths <100nm, poor smoothness causes excessive scattered light. A wide range of materials can be used such as Silicon, Borosilicate glasses, Fused Silica, Sapphire, Calcium Fluoride, Magnesium Fluoride or Crystals such as Quartz, Germanium, YB66, Beryl, or other crystals or any suitable material that can be bonded to be conformal to the optical substrate. d. A monochromator with a thin platelet crystal or a plurality of thin platelet crystals arranged in an adjacent array configuration on a substrate to occupy the optical field of view of interest. i. Platelets are thin down to 120 um or less to be able to bend and be optically bonded conformal to the substrate. ii. Platelets are polished to 0.5 nm or less to be able to be optically bonded. iii. Platelets should be aligned to the diffracting crystal planes within a few arc seconds. iv. If a plurality of platelets is to be bonded to the substrate, the relative alignment error between planes of different platelets should not exceed 1 arc second across the platelets (length and width) to achieve optimal focusing properties.v. Metrology of crystal platelets should include alignment verification across multiple locations of each of the respective platelets. vi. Substrate ellipsoidal or toroidal are polished to 0.5 nm or less. vii. The polished side of the platelets are bonded to the polished face of the substrate. e. Depending on the desired soft X-ray energy, multilayer (ML) coatings can be designed and deposited on final optical assembly (substrate-i- platelet). f. For the higher energy soft x-rays (~ above 0.8 keV), crystals can be used as Bragg reflectors. For example, the most common x-ray energy utilized in XPS is AlKa (1486.7eV) which is typically transported and focused onto a wafer surface via a monochromator, an ellipsoidal or toroidal substrate (see Fig.l) populated with quartz (100) crystal platelets provides point-to point focus of the target emission to the sample surface with an energy bandwidth ~0.5eV. The advantage of these systems is that monochromators with large angular acceptance and thus high transport efficiency can be manufactured. A monochromator focusing system of this type may also transport when optimized for the 1storder Bragg diffraction for AlKa can also focus discrete higher order diffraction orders (energies) according to nk=2d sin(0) (d is the crystal lattice spacing) to the wafer surface. However, the coverage of focusable energies is discrete by nature and intermediate energies other than n . equivalent can, by design, not be transported to the sampling area. Lower x-ray energies are not accessible or focusable at the sample surface with such a monochromator and would require a larger 2d lattice spacing applied to the substrate. g. The platelet can be fabricated from a crystalline material to allow Bragg reflection from the undeformed crystal planes near the reflecting surface. The thin platelets can be a material such as Silicon, Borosilicate glasses, Fused Silica, Sapphire, Calcium Fluoride, Magnesium Fluoride or Crystals such as Quartz, Germanium, YB66 or other crystals or any suitable material that can be bonded to be conformal to the optical substrate.h. A monochromator composed of a thin platelet crystal, or a plurality of thin platelet crystals arranged in an adjacent array configuration on a substrate. The number of platelets can be 1 or a plurality of thin platelets to cover the optical field of view of interest. (See fig 2) i. Multilayer coatings can be designed and optimized for narrow wavelength reflection made of the following (but not limited): Molybdenum / Silicon (Mo / Si), Niobium / Silicon (Nb / Si), Ruthenium / Boron (Ru / B), Tungsten / Carbon (W / C), Platinum / Carbon (Pt / C), Nickle / Cobalt (Ni / Co), Chrome / Carbon Cr / C, Scandium / Carbon (Sc / C), Nickel / carbon (Ni / C), Molybdenum / carbon (Mo / C) j. Platelets can be optically bonded to substrates via multiple methods such as Adhesives, UV activated adhesives, techniques used silicon-to silicon bonding or optical bonding. However, the preferred method is optical bonding. One major disadvantage to other techniques is they cannot be adjusted after bonding. k. Platelets and substrates cleaned by oxygen plasma cleaning or UVO cleaning prior to the optically bonding step. l. Debonding: UV light can be used the de-bond the platelets to 1) realignment, 2) refurbish, 3) replaced damage platelets. Wavelength below 450 nm down to the absorption edge of platelet material can be used. UV sources can be (but not limited to any UV sources produced by a discharge plasma source, RF source or other. The plasma source could be N2, 02, Ar Kr, Ne, or any mixtures. m. Platelet thinning, depending on the material, platelets can thin down to less than -120 microns to handle any associated bend stress (e.g., stress from contacting them to a highly curved substrate). A number of platelets and materials are designed also to handle any associated bend stress and for ease of assembly and alignment.Multiple platelets should conform to relative flatness and crystal plane alignment errors of 1 arc second or less across each and the multitude of platelets.n. Platelet could have a printed, embossed, etched, etched grating or Fresnel lens-like set of reflecting ridges. Presumably easier to fabricate while flat, and then bend to shape.

[0063] Figure 5 illustrates an example of method 200 for manufacturing a soft X-ray monochromator.

[0064] According to an embodiment, method 200 includes step 210 of obtaining a substrate that comprises a polished curved surface. Obtaining include manufacturing or receiving.

[0065] According to an embodiment, step 210 is followed by step 220 of optically bonding to the polished curved surface one or more platelets having one or more corresponding polished surfaces; wherein the one or more platelets are bent to follow a curvature of the polished curved surface.

[0066] According to an embodiment the optically bonding does not use a dedicated bonding material to be positioned between the polished curved surface and the one or more platelets.

[0067] According to an embodiment the platelets are coated with a coating. According to an embodiment, method 200 includes coating a platelet of the one or more platelets with a coating. According to an embodiment the one or more platelets are received after being coated.

[0068] According to an embodiment, the outcome of method 200 is any soft X-ray reflectometer as illustrated in the application.

[0069] According to an embodiment, method 200 includes debonding a platelet of the one or more platelets and replacing the platelet with a replacement platelet. The replaced platelet may be defective or may be replaced by any other reason. According to an embodiment, the replacement is performed following a completion of the manufacturing.

[0070] Figure 6 illustrates an example of method 300 for using a soft X-ray monochromator.

[0071] According to an embodiment, method 300 includes step 310 of receiving, by the soft X-ray monochromator, an input X-ray beam.

[0072] According to an embodiment, step 310 is followed by step 320 of outputting, by the soft X-ray monochromator, a focused monochromatic X-ray beam. The soft X-ray monochromator comprises a substrate that comprises a polished curved surface; and oneor more platelets having one or more corresponding polished surfaces that are optically bonded to the polished curved surface; wherein the one or more platelets are bent to follow a curvature of the polished curved surface.

[0073] According to an embodiment, method 300 used any soft X-ray reflectometer as illustrated in the application.

[0074] In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the broader spirit and scope of the invention as set forth in the appended claims.

[0075] Moreover, the terms “front,” “back,” “top,” “bottom,” “over,” “under” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

[0076] The connections as discussed herein may be any type of connection suitable to transfer signals from or to the respective nodes, units or devices, for example via intermediate devices. Accordingly, unless implied or stated otherwise, the connections may for example be direct connections or indirect connections. The connections may be illustrated or described in reference to being a single connection, a plurality of connections, unidirectional connections, or bidirectional connections. However, different embodiments may vary the implementation of the connections. For example, separate unidirectional connections may be used rather than bidirectional connections and vice versa. Also, plurality of connections may be replaced with a single connection that transfers multiple signals serially or in a time multiplexed manner. Likewise, single connections carrying multiple signals may be separated out into various different connections carrying subsets of these signals. Therefore, many options exist for transferring signals.

[0077] Although specific conductivity types or polarity of potentials have been described in the examples, it will be appreciated that conductivity types and polarities of potentials may be reversed.

[0078] Each signal described herein may be designed as positive or negative logic. In the case of a negative logic signal, the signal is active low where the logically true state corresponds to a logic level zero. In the case of a positive logic signal, the signal is active high where the logically true state corresponds to a logic level one. Note that any of the signals described herein may be designed as either negative or positive logic signals. Therefore, in alternate embodiments, those signals described as positive logic signals may be implemented as negative logic signals, and those signals described as negative logic signals may be implemented as positive logic signals.

[0079] Furthermore, the terms "assert" or “set" and "negate" (or "de-assert" or “clear”) are used herein when referring to the rendering of a signal, status bit, or similar apparatus into its logically true or logically false state, respectively. If the logically true state is a logic level one, the logically false state is a logic level zero. And if the logically true state is a logic level zero, the logically false state is a logic level one.

[0080] Those skilled in the art will recognize that the boundaries between logic blocks are merely illustrative and that alternative embodiments may merge logic blocks or circuit elements or impose an alternate decomposition of functionality upon various logic blocks or circuit elements. Thus, it is to be understood that the architectures depicted herein are merely exemplary, and that in fact many other architectures may be implemented which achieve the same functionality.

[0081] Any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality may be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being "operably connected," or "operably coupled," to each other to achieve the desired functionality.

[0082] Furthermore, those skilled in the art will recognize that boundaries between the above-described operations merely illustrative. The multiple operations may be combined into a single operation, a single operation may be distributed in additional operations and operations may be executed at least partially overlapping in time. Moreover, alternativeembodiments may include multiple instances of a particular operation, and the order of operations may be altered in various other embodiments.

[0083] However, other modifications, variations and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense.

[0084] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the terms “a” or “an,” as used herein, are defined as one or more than one. Also, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an." The same holds true for the use of definite articles. Unless stated otherwise, terms such as “first" and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

[0085] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

WE CLAIM1. A soft X-ray monochromator comprising: a substrate that comprises a polished curved surface; and one or more platelets having one or more corresponding polished surfaces that are optically bonded to the polished curved surface; wherein the one or more platelets are bent to follow a curvature of the polished curved surface.

2. The soft X-ray monochromator according to claim 1 , wherein a thickness of each platelet does not exceed one hundred twenty nanometers.

3. The soft X-ray monochromator according to claim 1, wherein the one or more platelets are multiple platelets.

4. The soft X-ray monochromator according to claim 3, wherein the multiple pallets are spaced apart from each other and wherein a distance between adjacent platelets of the multiple platelets is smaller than widths of the adjacent platelets.

5. The soft X-ray monochromator according to claim 3, wherein the multiple platelets are arranged in a two dimensional array.

6. The soft X-ray monochromator according to claim 5, wherein a relative pointing error of the platelets of the set does not exceed 1 arc second.

7. The soft X-ray monochromator according to claim 1, wherein the one or more platelets are one or more crystalline platelets.

8. The soft X-ray monochromator according to claim 1, wherein the polished curved surface exhibits slope errors of less than 1 arc sec and with a roughness of less than 0.2 nm.

9. The soft X-ray monochromator according to claim 1, wherein the polished curved surface has an ellipsoidal shape and having a geometry that is defined by x2 / a2+y2 / b2+ z2 / b2=1, wherein c is a half conjugate distance, a and b are variables, x is an x-axis coordinate, y is an y-axis coordinate, z is an z-axis coordinate, wherein a ratio between c and b is a set based on a Bragg angle associated with soft X-ray monochromator, a rocking curve of the crystal, and an admitted x-ray line width.

10. The soft X-ray monochromator according to claim 1, wherein the soft X-ray monochromator is configured to operate at wavelengths between 0.8-10 keV, and wherein the polished curved surface exhibits a roughness of less than 0.5 nm.

11. The soft X-ray monochromator according to claim 1 , wherein the soft X-ray monochromator is configured to operate at wavelengths between 0.025 to 0.79 keV, and wherein the polished curved surface exhibits a roughness of less than 0.2 nm.

12. The soft X-ray monochromator according to claim 1, wherein the one or more platelets are coated with a multilayer coating.

13. The soft X-ray monochromator according to claim 1, wherein the soft X-ray monochromator is configured to operate at wavelengths between 1.1 to 2 keV and wherein the one or more platelets are made of YB66 monochromator crystals.

14. The soft X-ray monochromator according to claim 1, wherein the soft X-ray monochromator is configured to operate at a wavelength of 5.4 keV and wherein the one or more platelets are one or more single crystal germanium platelets.

15. The soft X-ray monochromator according to claim 1, wherein the soft X-ray monochromator is configured to operate at a wavelength selected out of 1.4, 1.49 or 5.9 keV and wherein the one or more platelets are made of quartz.

16. The soft X-ray monochromator according to claim 1, wherein at least one platelet is a replacement platelet that replaces a de-bonded platelet.

17. A method for manufacturing a soft X-ray monochromator, the method comprises: obtaining a substrate that comprises a polished curved surface; and optically bonding to the polished curved surface one or more platelets having one or more corresponding polished surfaces; wherein the one or more platelets are bent to follow a curvature of the polished curved surface.

18. The method according to claim 17 further comprising debonding a platelet of the one or more platelets and replacing the platelet by a replacement platelet.

19. The method according to claim 17, further comprising coating a platelet of the one or more platelets with a coating.

20. The method according to claim 19, wherein the coating is a multilayer coating.

21. The method according to claim 17, wherein a thickness of each platelet does not exceed one hundred twenty nanometers.

22. The method according to claim 17, wherein the one or more platelets are multiple platelets.

23. The method according to claim 19, wherein the multiple pallets are spaced apart from each other and wherein a distance between adjacent platelets of the multiple platelets is smaller than widths of the adjacent platelets.

24. The method according to claim 19, wherein the multiple platelets are arranged in a two dimensional array.

25. The method according to claim 24, wherein a relative pointing error of the platelets of the set does not exceed 1 arc second.

26. The method according to claim 17, wherein the one or more platelets are one or more crystalline platelets.

27. The method according to claim 17, wherein the polished curved surface exhibits slope errors of less than 1 arc sec and with a roughness of less than 0.2 nm.

28. The method according to claim 17, wherein the polished curved surface has an ellipsoidal shape and having a geometry that is defined by x2 / a2+y2 / b2+ z2 / b2= 1 , wherein c is a half conjugate distance, a and b are variables, x is an x-axis coordinate, y is an y-axis coordinate, z is an z-axis coordinate, wherein a ratio between c and b is a set based on a Bragg angle associated with soft X-ray monochromator, a rocking curve of the crystal, and an admitted x-ray line width.

29. The method according to claim 17, wherein the soft X-ray monochromator is configured to operate at wavelengths between 0.8-10 keV, and wherein the polished curved surface exhibits a roughness of less than 0.5 nm.

30. The method according to claim 17, wherein the soft X-ray monochromator is configured to operate at wavelengths between 0.025 to 0.79 keV, and wherein the polished curved surface exhibits a roughness of less than 0.2 nm.

31. The method according to claim 17, wherein the one or more platelets are coated with a multilayer coating.

32. The method according to claim 17, wherein the soft X-ray monochromator is configured to operate at wavelengths between 1.1 to 2 keV and wherein the one or more platelets are made of YB66 monochromator crystals.

33. The method according to claim 17, wherein the soft X-ray monochromator is configured to operate at a wavelength of 5.4 keV and wherein the one or more platelets are one or more single crystal germanium platelets.

34. The method according to claim 17, wherein the soft X-ray monochromator is configured to operate at a wavelength selected out of 1.4, 1.49 or 5.9 keV and wherein the one or more platelets are made of quartz.

35. A method for using a soft X-ray monochromator, the method comprises: receiving, by the soft X-ray monochromator, an input X-ray beam; and outputting, by the soft X-ray monochromator, a focused monochromatic X- ray beam; wherein the soft X-ray monochromator comprises a substrate that comprises a polished curved surface; and one or more platelets having one or more corresponding polished surfaces that are optically bonded to the polished curved surface; wherein the one or more platelets are bent to follow a curvature of the polished curved surface.

36. The method according to claim 35, wherein a thickness of each platelet does not exceed one hundred twenty nanometers.

37. The method according to claim 35, wherein the one or more platelets are multiple platelets.

38. The method according to claim37 , wherein the multiple pallets are spaced apart from each other and wherein a distance between adjacent platelets of the multiple platelets is smaller than widths of the adjacent platelets.

39. The method according to claim 37, wherein the multiple platelets are arranged in a two dimensional array.

40. The method according to claim 39, wherein a relative pointing error of the platelets of the set does not exceed 1 arc second.

41. The method according to claim 35, wherein the one or more platelets are one or more crystalline platelets.

42. The method according to claim 35, wherein the polished curved surface exhibits slope errors of less than 1 arc sec and with a roughness of less than 0.2 nm.

43. The method according to claim 35, wherein the polished curved surface has an ellipsoidal shape and having a geometry that is defined by x2 / a2+y2 / b2+ z2 / b2=35, wherein c is a half conjugate distance, a and b are variables, x is an x-axis coordinate, y is an y-axis coordinate, z is an z-axis coordinate, wherein a ratiobetween c and b is a set based on a Bragg angle associated with soft X-ray monochromator, a rocking curve of the crystal, and an admitted x-ray line width.

44. The method according to claim 35, wherein the soft X-ray monochromator is configured to operate at wavelengths between 0.8-10 keV, and wherein the polished curved surface exhibits a roughness of less than 0.5 nm.

45. The method according to claim 35, wherein the soft X-ray monochromator is configured to operate at wavelengths between 0.025 to 0.79 keV, and wherein the polished curved surface exhibits a roughness of less than 0.2 nm.

46. The method according to claim 35, wherein the one or more platelets are coated with a multilayer coating.

47. The method according to claim 35, wherein the soft X-ray monochromator is configured to operate at wavelengths between 1.1 to 2 keV and wherein the one or more platelets are made of YB66 monochromator crystals.

48. The method according to claim 35, wherein the soft X-ray monochromator is configured to operate at a wavelength of 5.4 keV and wherein the one or more platelets are one or more single crystal germanium platelets.

49. The method according to claim 35, wherein the soft X-ray monochromator is configured to operate at a wavelength selected out of 1.4, 1.49 or 5.9 keV and wherein the one or more platelets are made of quartz.

50. The method according to claim 35, wherein at least one platelet is a replacement platelet that replaced a de -bonded platelet.

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