Full beam metrology for x-ray scatterometry system

Abstract

To provide methods and systems for characterizing dimensions and material properties of semiconductor devices by full beam X-ray scatterometry.SOLUTION: A method 300 of measuring full beam X-ray scatterometry includes illuminating a sample with an X-ray beam (block 301), and detecting the intensities of the resulting zero diffraction order and higher diffraction orders simultaneously for one or more angles of incidence relative to the sample (block 302). The simultaneous measurement of the direct beam and the scattered orders enables high throughput measurements with improved accuracy. A full beam X-ray scatterometry system includes: one or more photon counting detectors; and thick, highly absorptive crystal substrates that absorb the direct beam with minimal parasitic backscattering. Model based measurements are performed based on a zero diffraction order beam, and measurement performance of the full beam X-ray scatterometry system is estimated based on properties of the measured zero order beam.SELECTED DRAWING: Figure 14

Description

[Technical field]

[0001] The described embodiments relate to metrology systems and methods, and more particularly to improving measurement accuracy. The present invention relates to a method and system for performing [Background technology]

[0002] This patent application is a joint venture of U.S. Provisional Patent Application No. 119 filed on October 18, 2016. Priority is claimed from patent application Ser. No. 62 / 409,758, the subject matter of which is incorporated herein by reference in its entirety. To quote.

[0003] Semiconductor devices such as logic and memory elements are processed by a series of processing steps applied to the specimen. The various features and multiple structural levels of a semiconductor device are typically fabricated using For example, lithography, among other processes, is a process for forming a semiconductor wafer. It is a process in semiconductor fabrication that involves creating patterns on a substrate. Further examples of processes include, but are not limited to, chemical-mechanical polishing, etching, deposition, and ion implantation. Multiple semiconductor devices are fabricated on a single semiconductor wafer and then The individual semiconductor devices can then be separated into individual semiconductor elements.

[0004] The metrology process is designed to detect defects on the wafer to promote higher yields. It is used at various steps during the semiconductor manufacturing process. Several metrology-based techniques, including performing optical and reflectance measurements, as well as related analytical algorithms, are The algorithm determines the critical dimensions, thickness, composition, and other parameters of nanoscale structures. It is commonly used to characterize

[0005] Traditionally, scatterometry critical dimension (SCR) measurements are performed on thin films and / or repeated During device fabrication, these films are usually and periodic structures represent the geometry and material structure of the actual element, or intermediate designs. The elements (e.g. logic elements or memory elements) are scaled to smaller nanometer-scale dimensions. As we move to a more dimensional approach, characterization becomes more difficult. Devices incorporating materials with physical properties contribute to the difficulty of characterization. The storage structures are often three-dimensional structures with high aspect ratios, which makes it difficult for light emission to occur. Optical measurement tools that use infrared light to make it visible can penetrate through semi-transparent materials. Longer wavelengths, which can penetrate many layers of material but provide good penetration depth, It does not provide sufficient sensitivity to small anomalies. Furthermore, it is difficult to measure the sensitivity of complex structures (e.g. FinFE). The increasing number of parameters required to characterize T) is due to the increasing correlation of the parameters. As a result, the parameters characterizing the target are difficult to ascertain using the available measurements. In fact, decoupling is often not possible.

[0006] In one example, longer wavelengths (e.g., near infrared) alternatingly ionize the polysilicon in the stack. This is an attempt to solve the penetration issue of 3D flash elements, which are used as one of the materials to But the mirror-like structure of 3D flash allows the light to travel through the stack of layers. As the light propagates deeper into the cavity, it essentially reduces its intensity. This reduces the sensitivity at deeper locations. In this context, only SCD offers high sensitivity and With a low correlation, a reduced set of metrology dimensions can be accurately extracted.

[0007] In another example, opaque high-k materials are increasingly being used in advanced semiconductor structures. Optical radiation is often unable to penetrate layers constructed of these materials. As a result, Measurement of thin layers using scatterometry tools such as ellipsometers or reflectometers can be challenging. It's increasing.

[0008] In response to these challenges, more sophisticated optical metrology tools have been developed. From the angle of illumination, shorter wavelength of illumination, wider range of wavelength of illumination, and reflected signal Obtaining more complete information (e.g., in addition to more traditional reflectivity or ellipsometric signals) Tools involving the measurement of multiple Mueller matrix elements have been developed. The probe is capable of detecting many advanced targets, including complex 3D structures and structures smaller than 10 nm. Measurement and measurement applications (e.g. roughness of line edges, and line width roughness measurements) .

[0009] Atomic force microscopes (AFM) and scanning tunneling microscopes (STM) provide atomic resolution. However, these only allow for detailed examination of the surface of the specimen. FM and STM microscopes require long scanning times. Scanning electron microscopes (SEMs) It provides a moderate level of resolution, but does not penetrate structures to a sufficient depth. However, high aspect ratio holes cannot be well characterized. Furthermore, the charge required for the specimen is too large for imaging. X-ray reflectometers also have penetration challenges, which can be adversely affected by high aspect ratio structures. Limit the effectiveness of X-ray reflectometers when measuring the body.

[0010] To solve the problem of penetration depth, conventional imaging methods such as transmission electron microscope (TEM) and SEM were used. The technology includes focused ion beam (FIB) processing, ion milling, blanket etching, etc. These techniques are often used in conjunction with destructive sample preparation techniques such as selective etching or selective etching. M achieves a high resolution level and allows exploration to any depth, whereas TEM is destructive to the specimen. Typically, several iterations of material removal and measurement are required to It provides the information necessary to measure important metrology parameters across a dimensional structure, but However, these techniques require sample destruction and long processing times. The complexity and time to complete the measurement depends on the drift of the etch and the measurement stage. Furthermore, these techniques introduce registration errors. It requires a lot of repetition.

[0011] X-ray scatterometry systems have shown promise for addressing challenging measurement applications However, current implementations block the zeroth order and collect only the scattered orders. This approach This leads to several drawbacks. First, the direct beam and the scattered orders are not collected simultaneously. Secondly, the direct beam is many orders brighter than the collected scattered orders. Therefore, high signal-to-noise ratio (SNR) beam and system information is lost. , the signal information embedded in all the scattered light, which is a function of the scattering angle, is lost.

[0012] Despite these drawbacks, measurements relying only on scattered orders are very stable in terms of the input beam. Determine some property of the specimen of interest, so long as it is known or well characterized. In some instances, the incident flux is measured periodically. , which allows the deflection of the light beam to be corrected during the measurement. In many cases, this approach is either too slow, not accurate enough, or both. This is the way.

[0013] In current X-ray scatterometry systems, the linear beam is interrupted for several reasons. One is that available detectors cannot resolve signals with large dynamic ranges. In typical semiconductor measurement applications, the scattered signal is generally 5-7 times weaker than the straight beam. Furthermore, a relatively high flux directional beam picks up the charge on the detector. This can cause the sensor to max out beyond the damage threshold. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] U.S. Patent No. 9,243,886 [Patent Document 2] US Patent Application Publication No. 2016 / 0202193 Summary of the Invention [Problem to be solved by the invention]

[0015] To further improve device performance, the semiconductor industry is focusing on vertical rather than lateral scaling. Therefore, it is possible to precisely fabricate complex and complete three-dimensional structures. Measurement is critical to ensure viability and drive continued scaling. Furthermore, metrology applications are facing increasing demands for finer resolution, multi-parameter correlation, and high accuracy. Increasingly complex geometry structures, including aspect ratio structures, and the increasing use of opaque materials Therefore, improved X-ray scatterometry is required. Certain methods and systems are desired. [Means for solving the problem]

[0016] Full beam X-ray scatterometry characterizes the dimensional and material properties of semiconductor devices DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Methods and systems for detecting and managing network traffic are described herein.

[0017] In one embodiment, full beam X-ray scatterometry measurements are performed by measuring the X-ray beam. Irradiating the sample and measuring the intensity of the light for one or more angles of incidence on the sample. Simultaneously detecting the intensities of the zeroth diffraction order and higher diffraction orders. High throughput with improved accuracy by simultaneously measuring beam and scattered orders Enables measurements.

[0018] In a further aspect, the full beam X-ray scatterometry system has a high dynamic range ( For example, 10 5 and one or more photon-counting detectors with a 100 nm or larger diameter (100 nm or larger) and a rectilinear beam that is a thick, highly absorbing crystalline substrate that absorbs with minimal parasitic backscattering without interference; In some embodiments, a single photon-counting detector includes a detector for detecting the position of a detected photon. In some embodiments, the X-ray detector detects one or more X-ray photons. Decompose the energy of.

[0019] In another aspect, the detector detects damage and excess charging from the incident zeroth order beam. To mitigate, it is scrutinized against incoming x-rays.

[0020] In yet another embodiment, the overlapping diffraction orders at the detector are divided into a measured zero-order beam The analysis is based on the shape of the

[0021] In yet another aspect, the profile of the zeroth order beam is extracted during the measurement. This reduces drift in the

[0022] In yet another embodiment, the intensities of the higher diffraction orders are measured relative to the zeroth order beam. In some embodiments, the intensity of each higher diffraction order is estimated as a simple sum of the intensities. The measured zeroth order beam is estimated by a simple division or other method. The measurement uncertainties associated with relatively weaker, higher order signals are greatly reduced.

[0023] In a further aspect, the measurement quality and performance of a full beam X-ray scatterometry system The efficiency is estimated based on the measured properties of the zeroth order beam. Characteristics include, but are not limited to, beam shape, intensity, location, profile, tilt, rotation, non-linearity, etc. symmetry, or any combination thereof.

[0024] In another aspect, the measurement quality and performance of the metrology system can be evaluated by measuring the zeroth order beam. In some examples, the measurement quality and performance estimates described above are used to control the is provided as an input to the feedback controller. The control commands communicate with the measurement system to improve its quality and performance. A change in the state of one or more elements of a measurement system.

[0025] In some embodiments, the full beam X-ray scatterometry based metrology comprises measuring The dimensions of the sample are determined by inverse solution of a given measurement model using the measured data. The measurement model includes several (approximately 10) adjustable parameters and the outline of the sample piece. and the optical properties of the measurement system. However, model-based regression, tomography techniques, machine learning, or any combination thereof may be used. In this way, the parameters of the target profile are determined by the measured scattering Parameterized measurements that minimize the error between the measured X-ray intensity and the modeled results It is estimated by solving for the value of the model.

[0026] In yet another embodiment, the measured zero-order intensity is used to fit the measurement model during regression. Provided as input.

[0027] In yet another aspect, the divergence of the measured orders is determined based on a model of the measurement target. are taken into account in the measurement model associated with

[0028] In yet another embodiment, the metrology system may include a structural model (e.g., Generate a model (e.g. exterior model, material model, or a combination of exterior model and material model) From the structural model, full beam X-rays including at least one contour parameter are a scatterometry response model generating unit configured to generate a scatterometry response model; and and performing a combined analysis to determine a parameter value for at least one specimen. In this way, the simulated full-beam X-ray scatterometry signal is measured. By comparing with the data obtained from the previous study, the outline of the sample as well as the electron density and elemental identification and It is then possible to determine material properties such as the thickness and composition.

[0029] In another embodiment, an initial estimate of one or more parameter values ​​of the subject is For full-beam X-ray scatterometry measurements performed at a single orientation of the incident X-ray beam The initial estimate is used as the starting value for the parameter of interest in multiple orientations. This is carried out to regress the measurement model using the measurement data collected from the measurement of In this method, a fine estimate of the parameters of interest is determined with a relatively small amount of computation, and this fine estimate By performing the estimation as a starting point for a regression across a larger data set, Exact estimates of the elephant's parameters are obtained with a small overall computational effort.

[0030] In another embodiment, full beam X-ray scatterometry measurement data is used to detect Based on the measured intensities of the selected diffraction orders, an image of the measured structure is generated. In an embodiment, a response function model is derived to estimate scattering from a mesh of general electron density. This model is then fitted to the measured signal while accounting for both continuity and scattered edges. To enhance the simulation, the electron density modeled in this mesh is trapped, This results in a three-dimensional image of the device.

[0031] The foregoing is a summary and thus necessarily contains simplifications and generalizations and omits details. Accordingly, those skilled in the art will appreciate that the Summary is illustrative only and not in any way limiting. Other aspects, inventive features, and device advantages and / or features described herein. The process will become apparent in the non-limiting detailed description provided herein. [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 illustrates a metrology system 100 configured to perform full-beam X-ray scatterometry measurements according to the methods described herein. [Diagram 2] FIG. 2 illustrates another embodiment of a metrology system 200 configured to perform full beam X-ray scatterometry measurements according to the methods described herein. [Diagram 3] FIG. 1 shows an image 171 of scattered orders measured by a full-beam metrology system, such as metrology system 100. [Figure 4] FIG. 1 shows an image 172 of scattered orders measured by a full-beam metrology system, such as metrology system 100. [Diagram 5] FIG. 5 shows a plot 173 of the intensity profile associated with cross section C of the image 172 shown in FIG. [Figure 6] FIG. 13 shows the scattering efficiency of a zero-order beam as a function of the angle of incidence. [Figure 7] FIG. 13 shows the scattering efficiency of several higher orders as a function of the angle of incidence. [Figure 8] FIG. 1 shows elements of metrology systems 100 and 200 contained in a vacuum environment separate from the specimen 101. [Figure 9] FIG. 1 illustrates an analysis engine 150 configured to build a model and determine parameter values ​​for a specimen based on full beam X-ray scatterometry data according to methods described herein. [Figure 10A] 1 is an isometric view of a typical 3D flash memory device 190 that is subject to measurement in the manner described herein. [Figure 10B] FIG. 1 is a top view of a typical 3D flash memory device 190 that is subject to measurement in the manner described herein. [Figure 10C]1 is a cross-sectional view of a typical 3D flash memory device 190 that is subjected to measurements in the manner described herein. [Figure 11] 1 shows a beam of X-ray radiation 117 incident on a wafer 101 at particular orientations represented by angles φ and θ. [Figure 12] FIG. 3 is a top view of an array of high aspect ratio hole structures 310. [Figure 13A] FIG. 3 is a side view of an exemplary high aspect ratio hole structure 320. [Figure 13B] FIG. 3 is a side view of the inclined hole structure 321. [Figure 13C] FIG. 3 is a side view of a progressively sloped hole structure 322, in which the degree of slope increases progressively with depth. [Figure 14] 3 is a flow chart illustrating an example method 300 for measuring a structure based on full beam x-ray scatterometry measurements as described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Reference will now be made in detail to background examples and certain embodiments of the present invention, examples of which are included in the accompanying drawings. As shown in the drawings.

[0034] Full beam X-ray scatterometry characterizes the dimensional and material properties of semiconductor devices Methods and systems for implementing such systems and techniques are described herein. measures the structural and material properties associated with different semiconductor fabrication processes In some instances, full beam X-ray scatterometry is used to Although there is no such memory, spin-transfer torque random access memory (STT-RAM), 3D NAND memory (3D-NAND) or vertical NAND memory (V-NAND), Dynamic Random Access Memory (DRAM), Three-Dimensional Flash Memory (3D-FLASH ASH), Resistive Random Access Memory (Re-RAM), and Phase Change Random Access Memory (PRAM) Critical dimensions, thicknesses, and thicknesses of high aspect ratio semiconductor structures, including PC-RAMs, It is utilized to measure overlay as well as material properties.

[0035] In one embodiment, full beam X-ray scatterometry measurements are performed by measuring the X-ray beam. Irradiating the sample and detecting zeros occurring at one or more angles of incidence to the sample. Simultaneous detection of the intensities of the first and higher diffraction orders. Simultaneous measurement of disturbed orders allows for high throughput measurements with improved accuracy In some embodiments, the zeroth order beam is measured without a standard beam block. It can be used by executing

[0036] The use of high-brightness full-beam X-ray scatterometry delivers high flux X-ray radiation to the target. It allows penetration into opaque areas of objects. It uses full beam X-ray scatterometry. Examples of profile parameters that can be measured include hole size, hole density, line edge roughness, line width, etc. Roughness, sidewall angle, profile, critical dimensions, overlay, edge position error, and pin Examples of measurable material parameters include electron density. In some instances, full beam X-ray scatterometry is capable of measuring features smaller than 10 nm. STT-RAM, V-RAM, and V-RAM are required for the measurement of external and material parameters. Measurement of advanced semiconductor structures such as NAND, DRAM, PC-RAM, and Re-RAM This makes it possible to

[0037] A typical X-ray scatterometry system collects the higher diffraction orders while The zeroth order beam is blocked using a lock. However, in many semiconductor metrology applications, This prevents accurate measurement. Logic elements in the back-end of the line (BEOL) part of the process flow, and memory (e.g., VNAND and For the 3D and DRAM, the pitch of the patterns is measured by a typical CD-SAXS system. As a result, the first and zeroth orders experience a significant amount of spatial overlap at the detector. If a beam block is used to block the zeroth order, one of the first order beams This is due to the measurement error of the intensity of the first beam and the fact that the This will cause errors in any X-ray scatterometry measurement. Generally, the first order beam is The first order beam has a much greater diffraction efficiency than the higher order beams. It is important for accurate measurements. Without the 1st order beam, the measurement would be confined to the higher order beams. The diffraction efficiency of orders higher than the first is much weaker than that of the first diffraction order. This significantly reduces the measurement time to achieve an adequate signal-to-noise ratio (SNR). Increase.

[0038] FIG. 1 illustrates a metrology diagram for measuring a feature of a specimen according to an exemplary method presented herein. 1 illustrates an embodiment of a tool 100. As shown in FIG. 1, the system 100 can be used to A full beam is then applied across the inspection area 102 of the specimen 101 disposed on the positioning system 140. In some embodiments, the inspection area may include a beam x-ray scatterometry measurement. 102 has a spot size of 80 micrometers or less. In some cases, the inspection area 102 has a spot size of 50 micrometers or less. In this embodiment, the test area 102 has a spot size of 40 micrometers or less. do.

[0039] In the illustrated embodiment, the metrology tool 100 performs full beam X-ray scatterometry measurements. In some embodiments, the X-ray radiation source 110 is configured to generate X-ray radiation suitable for measurement. In an embodiment, the X-ray irradiation system 110 has a resolution of 0.01 nanometers to 1 nanometer. The X-ray radiation source 110 is configured to generate a wavelength of The X-ray beam 117 is incident on the

[0040] Generally, high-brightness X-rays with sufficient flux levels to allow high throughput are used. In-line metrology can be performed on any suitable high brightness X-ray radiation source capable of producing full beam X-rays. It may be contemplated to provide X-ray radiation for linear scatterometry measurements. In one embodiment, the X-ray source is a tunable X-ray source capable of delivering X-ray radiation at different selectable wavelengths. Includes a monochromator capable of

[0041] In some embodiments, one that emits with a photon energy of greater than 15 keV. By using the above X-ray source, the X-ray source penetrates the entire element and the wafer substrate sufficiently. Non-limiting examples include particle acceleration sources, liquid accelerating sources, and Node source, rotating anode source, fixed solid anode source, microfocus source, micro Either a focussed rotating anode source or an inverse Compton source is used as the X-ray source 110. In one example, the L The inverse Compton source is available from Yncean Technologies, Inc. It may be contemplated that the inverse Compton source may generate X-rays over a range of photon energies, This has the added advantage that the X-ray source can deliver X-ray radiation at different selectable wavelengths. has.

[0042] An exemplary X-ray source bombards a solid or liquid target to stimulate X-ray emission. FIG. 2 illustrates an example method of the present invention, comprising: A metrology tool 200 for measuring features of a specimen is shown. Like numbered elements are similar. However, in the embodiment shown in FIG. The radiation source 110 is a liquid metal based X-ray irradiation system. The liquid metal 119 jet is The liquid metal is generated from a liquid metal container 111 and collected in a liquid metal collector 112. A circulation system (not shown) directs the liquid metal collected by the collector 112 to the liquid metal container 11. 1. The liquid metal 119 jet may include one or more elements. In a non-limiting example, The jet of solid metal 119 is composed of aluminum, gallium, indium, tin, thallium, and and bismuth. Thus, the liquid metal 119 jet contains In one embodiment, the liquid metal jet is a gallium ion beam. In some embodiments, the X-ray irradiation system 110 The electron beam is configured to generate a wavelength between 0.01 nanometers and 1 nanometer. The beam source 113 (e.g., an electron gun) produces a jet of liquid metal 119 via an electron optic 114. The electron beam is focused and the beam is directed toward the liquid metal. Suitable electro-optical elements 114 for directing the jet of light include electromagnets, permanent magnets, and electromagnetic A combination of a stone and a permanent magnet. A jet of liquid metal 119 and a stream of electrons 118. The coincidence of the X-ray beam 117 with the specimen 101 produces an X-ray beam 117 incident on the inspection area 102 of the specimen 101 .

[0043] A method and system for producing high brightness liquid metal x-ray radiation is disclosed herein in its entirety. No. 6,313,433, issued to KLA-Tencor Corp. on April 19, 2011, which is incorporated by reference. No. 7,929,667.

[0044] In one embodiment, the incident X-ray beam 117 is a 24.2 keV indium kα The X-ray beam is a multi-layer X-ray for full beam X-ray scatterometry measurements. Optics are used to collimate the beam to a divergence of less than 1 milliradian.

[0045] In some embodiments, the X-ray scattering measurements described herein involve the use of an X-ray source and This is achieved without the use of a screen positioned between the specimen. , full beam, over a range of incidence angles, multiple wavelengths, or a combination of both. The measured intensity can be used to measure the desired properties of the material (e.g., complex refractive index, electron density, etc.) of the measured structure. It provides enough information to resolve a distribution map (i.e., an image) of the distribution of the light (or absorption rate) of the light. In some other cases, pinholes are used to improve collimation of the X-ray beam. A separate opaque screen or other aperture is placed between the X-ray source and the specimen being measured. The intensity of the diffraction pattern is measured at several positions of the aperture. In some other embodiments, a script with a pseudorandom pattern of apertures is used. In this approach, a diffraction pattern is measured on multiple screens. , providing further information to resolve the three-dimensional distribution of the desired property of the material of the measured structure. It may also be contemplated to provide

[0046] In some embodiments, the profile of the incident X-ray beam is determined by two or more apertures. In another embodiment, the aperture is controlled by a slit, a slit, or a combination thereof. The aperture, slit, or both are configured to rotate in unison with the specimen orientation The input beam profile is optimized for each incidence angle, azimuth angle, or both. to.

[0047] As shown in FIG. 1, the X-ray optics 115 form an incident X-ray beam 117 and project the X-rays onto the workpiece 1. 01. In some examples, the X-ray optical element 115 includes an X-ray monochromator. The X-ray beam incident on the specimen 101 is monochromated. In one example, Loxley-T X-ray radiation can be detected by using a crystal monochromator such as the Anna-Bowen monochromator. In some examples, the X-ray optical element 115 may be a multi-layer X-ray optical element. The element is used to direct the X-ray beam 117 onto the inspection area 102 of the workpiece 101 at a distance of 1 milliradian. In some embodiments, the X-ray optical element collimates or focuses the X-ray beam with a divergence less than 100 nm. As the child 115, one or more of an X-ray collimating mirror, an X-ray aperture, an X-ray beam stop, X-ray refractive optical elements, diffractive optical elements such as zone plates, and mirror reflection elements such as grazing incidence ellipsoidal mirrors Diffractive X-ray optics, polycapillary optics such as hollow capillary X-ray waveguides, multilayer optics or systems, or any combination thereof. No. 2015 / 0110249, the contents of which are incorporated herein by reference in their entirety. It is listed in the number.

[0048] Typically, the focal plane of the illumination optical system is optimized for each measurement application. The stem 100 is configured to position the focal plane at various depths within the workpiece depending on the measurement application. can be.

[0049] The X-ray detector 116 collects the X-ray radiation 125 scattered from the workpiece 101 and generates a full beam A specimen 101 that is sensitive to incident X-ray radiation according to the mode of X-ray scatterometry measurement. In some embodiments, the scattered x-rays generate an output signal 126 indicative of a characteristic of the 125 is collected by the X-ray detector 116 while the specimen positioning system 140 Position and orient the specimen 101 to generate angularly resolved scattered x-rays .

[0050] In one embodiment, the full beam X-ray scatterometry system has a high dynamic range (e.g. For example, 10 5 One or more photon-counting detectors with a straight beam (i.e., zero A thick, highly absorbent material that absorbs the first order beam without damaging it and with minimal parasitic backscattering. and a non-absorbent crystalline substrate. In some embodiments, the single photon counting detector comprises: detects the position and number of detected photons.

[0051] Full beam X-ray scatterometry collects the zeroth order beam together with the higher diffraction orders. The zeroth order beam is several orders of magnitude more intense than the other orders. If the first order beam is not completely absorbed by the X-ray sensitive section of the detector, the zeroth order beam The intensity of these eddy current signals varies over the dynamic range of the measurement. For example, the eddy current signal is limited to 1 / 1 of the maximum luminous flux signal (i.e. the zeroth order beam). 0 4 If , the signals associated with many higher orders will be adversely affected. Therefore, a detector (e.g., detector 116) can detect high conversion of X-rays to electron-hole pairs. High X-ray absorption for increased efficiency and effective dynamic range of full-beam metrology It is important to show this.

[0052] Exemplary detector materials suitable for full-beam X-ray scatterometry include telluride. Cadmium (CdTe), Germanium (Ge), and Gallium Arsenide (GaAs) crystals In some embodiments, the detector material is The materials are selected to provide high conversion efficiency over a narrow energy band corresponding to the energy source.

[0053] In some embodiments, the thickness of the detector material is adjusted to provide the desired absorption of incoming x-rays. In some embodiments, the detector is selected to achieve Incoming X-ray beam (various diffraction orders) to increase the path length of the transmitted X-ray beam , thereby increasing the total absorption.

[0054] In some embodiments, a dual threshold detector is utilized to improve the SNR.

[0055] In another embodiment, the X-ray detector resolves one or more X-ray photon energies to identify the sample piece. In some embodiments, the present invention provides a method for generating an X-ray signal for each energy component of the X-ray that is characteristic of the X-ray energy component. In the present embodiment, the X-ray detector 116 may be a CCD array, a microchannel plate, a photodiode, or the like. Anode array, microstrip proportional counter, gas-filled proportional counter, scintillator, or a phosphor.

[0056] Thus, the interaction of X-ray photons within the detector is determined by pixel position and count number. In addition to the phase of the X-ray photons, the X-ray photons are differentiated by energy. The interaction is performed by dividing the energy of the X-ray photon interaction by a given upper threshold and a given lower threshold. In one embodiment, this information is used for further processing. and communicated via output signal 126 to computer system 130 for storage. .

[0057] In another aspect, the detector is adapted to mitigate damage and excess charging from the incidence of the zeroth order beam. In some embodiments, the detection The detector is designed to prevent the zero-order beam from staying too long at a particular point on the detector surface. In some other embodiments, the X-rays are continuously scanned for incoming X-rays. The detector is designed to prevent the zero-order beam from staying too long at a particular point on the detector surface. In some embodiments, the beam is periodically moved relative to the incoming x-rays to achieve a desired beam width. The scanning or cyclic movement is approximately perpendicular to the incoming X-rays. In some cases, the translation is rotation (e.g., the detector is rotated so that a particular point on the detector surface is in space). In some embodiments, the movement is A combination of parallel motions that move the incident point of the beam to various different points on the surface of the detector. be.

[0058] In another embodiment, a full beam X-ray scatterometry system is utilized to measure the zeroth order Based on the measured diffraction orders, including the scattered light, the properties of the specimen (e.g. structural parameters) can be determined. As shown in FIG. 1, the metrology tool 100 determines the and based at least in part on the obtained signal, The present invention also includes a computer system 130 that is utilized to determine the characteristics of the

[0059] Full-beam X-ray scatterometry measurements revealed that the high aspect ratio vertically fabricated The structure diffracts the collimated X-ray beam into diffraction orders. Each diffraction order has a particular The angular spacing of the diffraction orders is determined by the grid of the sample divided by the wavelength. The diffraction orders are inversely proportional to the molecular constant. The photons are detected by a detector array. Each pixel in the detector measures the number of photons that strike it. The arithmetic unit 10 outputs a signal indicating

[0060] The intensity of a diffracted order is of the form I(m,n,θ,φ,λ), where {m,n} is the diffracted order. The integer indices of the degrees, {θ,φ}, are the height and azimuth angles of the incident beam (i.e., is the polar coordinate of the incident chief ray relative to the coordinate system fixed on the wafer), and λ is the wavelength of the incident X-ray. do.

[0061] Several noise sources may interfere with the illumination light as it leaves the illumination and propagates towards the specimen. Exemplary disturbances include current fluctuations in the electron beam, temperature-induced optical drift, etc. The perturbed incident light flux is denoted as F0(1+n1).

[0062] The target scatters the incident radiation in a manner that depends on the azimuth and elevation angles of the incident beam. The effect of light scattering into order (m,n) is S mn It can be defined as (θ,φ). As the diffracted light travels from the specimen to the detector, the beam undergoes some change (1+n2 ) and parasitic noise (n3) affect all orders in the same way. Thus, the total intensity I of each order measured at time t is mn is expressed as (1) It can be represented by: I mn =S mn (θ,φ)(1+n2)(1+n1)F0t+n3(1)

[0063] FIG. 3 illustrates a scattering The image 171 of the zeroth order is shown. As shown in FIG. 3, the bright spot in the center of the image is the zeroth order beam. Can be associated.

[0064] The intensity of each order can be extracted in a number of ways. In some embodiments, The diffraction orders are spatially separated at the detector. In these embodiments, the diffraction orders are The output of pixels individually detected by the detector array and associated with the same diffraction order are combined (i.e., added). In this way, the detected diffraction orders are Each diffraction order is identified by integrating the number of photons in the pixel associated with it. This case is most useful when measuring features with relatively small pitch or when the divergence is relatively small. This is more likely to occur when making measurements using a beam with

[0065] In some other embodiments, the diffraction orders are spatially overlapped at the detector and The output of the filters can be easily combined to determine the intensity associated with a particular diffraction order. In these embodiments, a measurement model is utilized to analyze and detect the diffraction orders. Identify the measured intensity of each diffraction order emitted. In this case, the feature of a relatively large pitch is When measuring features or when measuring with a beam that has a relatively large divergence, is more likely to occur.

[0066] In another aspect, the overlapping orders are analyzed based on the shape of the measured zeroth order beam. In some embodiments, this analysis is performed in real time. The profile of the beam of any order (i.e., orders greater than 0) is the profile of the zeroth order beam. FIG. 4 illustrates a full-beam metrology system such as metrology system 100. FIG. 5 shows an image 172 of the scattered orders measured by the stem. A plot 173 of the intensity profile associated with cross section C of the image 172 is shown. The high intensity zero-order beam results in a very accurate beam profile, which is better. It is used to model higher diffraction orders.

[0067] In yet another aspect, the profile of the zeroth order beam is extracted during the measurement. This reduces drift in the

[0068] In some embodiments, the profile of the zero order beam is a target within the beam target. In some embodiments, the profile of the zeroth order beam is measured without involving any object. is measured with a non-scattering target in the beam path, so that the zero diffraction order is This is the only beam that is measured by the detector. In some embodiments, the zeroth order beam The profile is measured using a known target with known scattering properties.

[0069] In yet another embodiment, the intensities of the higher diffraction orders are determined based on the measured zeroth order beam. In some embodiments, the intensity of each higher diffraction order is estimated by a simple integral of the intensity. The measured zeroth order beam is estimated by a simple division or other method. Measurement uncertainties associated with relatively weaker, higher order signals are greatly reduced.

[0070] By estimating the intensities of the higher diffraction orders based on the simultaneously measured zeroth order beam, Thus, the scattered signal is isolated from system perturbations during data collection. Confusion due to misalignment of elements (e.g. slits, optical elements, spot shapes) and beam diameter Perturbations along the paths (e.g., n1 and n2) are mitigated in real time. By using all the scattered intensities, including The dependence of the scattered intensity on the incident light is decoupled from the perturbations of the light flux before and after the wafer.

[0071] The scattering efficiency of the measured specimen is calculated by dividing the extracted scattered intensity by the set of incidence angles {θ,φ}. The measurement is related to the shape and material of the measurement target. Scattering efficiency S of the second-order beam 00 As the path length increases, the incident angle increases. Because of the reduced penetration through the target at S 00 depends on the angle of incidence. When the angle aligns with the target scattering (e.g., normal incidence), the energy moves away from the zeroth order. Since the diffraction order is higher, S 00 depends on the angle of incidence.

[0072] FIG. 7 shows the scattering efficiency of several higher orders as a function of the angle of incidence θ. Line 174 is S 11 Plot line 175 shows S 13 Plot line 1 shows 76 is S 20 Plot line 177 shows S 22 Scattering of all higher orders The intensity of the scattering is generally dependent on the scattering depth or density. In general, the zero-order scattering efficiency decreases with increasing scattering depth, while the scattering efficiency of all other scattered orders increases with It increases as the disturbance depth increases.

[0073] The intensities of the higher diffraction orders are estimated based on the simultaneously measured zeroth order beam. This also increases the signal-to-noise ratio (SNR) of the sample, which allows for a greater degree of accuracy in terms of scattering depth and material density. This allows for more accurate measurements and therefore a more accurate estimation of the target profile. It becomes Noh.

[0074] In some instances, metrology based on full beam X-ray scatterometry can The method includes determining the dimensions of the sample by inverse solution of a predetermined measurement model using the data. The measurement model includes several (approximately 10) adjustable parameters, and determines the outer shape and The inverse solution method includes, but is not limited to, However, model-based regression, tomography techniques, machine learning, or any combination of these Thus, the parameters of the target profile are determined by the measurement of the scattered X-rays. A parameterized measurement model that minimizes the error between the measured intensities and the modeled results. is estimated by solving for the value of

[0075] In yet another embodiment, the measured zero-order intensity is used to fit the measurement model during regression. When the zeroth order is not measured, the total luminous flux is This will cause the value to vary with the parameter. This will result in a loss of accuracy. For all scattering orders other than order 1, the scattered intensity is a function of the scattering contrast only. However, for the zeroth order, the scattered intensity is The degree of change is a function of the absolute (i.e. unchanged) value of the refractive index. This additional information is Improve the accuracy of.

[0076] In yet another aspect, the divergence of the measured orders is determined based on a model of the measurement target. In some examples, each pixel is the average of the incidence angles {θ,φ} which differ slightly due to the divergence of the system, so the decomposed The beam has a scattering efficiency that depends on the pixels. For measurements based on a rometry-based model, the divergence is optimized to reduce the measurement time. It was found that the time between the two can be reduced. Too small a divergence increases the measurement time. Too much divergence leads to excessive correlation and loss of measurement precision.

[0077] In another aspect, the measurement quality and performance of the full beam X-ray scatterometry system is , is estimated based on the measured properties of the zeroth order beam. Such as, but not limited to, beam shape, intensity, location, profile, tilt, rotation, asymmetry sex, or any combination thereof.

[0078] In some cases, the brightness of the illumination source is the sum of all the light detected by the detector. In the absence of external perturbations, the total measured flux is estimated based on the target's absorption alone. In some instances, measurements are performed without a target. In these instances, Thus, the total measured luminous flux provides a direct estimate of the luminance of the source. In these embodiments, a target with known absorption characteristics is utilized. The intensity is estimated based on the measured luminous flux corrected by the absorption of known targets.

[0079] In some instances, the transmission efficiency of a system is the ratio of the total light detected by the detector to the total light In these examples, the light emitted by the source is estimated based on the sum of As it exits, it is measured before interacting with the illumination optics. It is then detected by the detector. The light flux between the light detected by the detector and the light emitted by the illumination source is The ratio provides an estimate of the transmission efficiency of the optical system. In some other instances, targets with known absorption characteristics are utilized. can be.

[0080] In some instances, the relative alignment of the detector to the beam axis is The estimated zeroth order beam location is based on the location of the incident zeroth order beam.

[0081] In some instances, imperfections or misalignments in the optical subsystem are measured by the detector. The zeroth order beam is estimated based on the shape (e.g., asymmetry, roughness, rotation) of the beam. Any imperfections or misalignment of the optical elements, slits, apertures, illumination sources, etc. that form this In many instances, the errors in the tilt of the illumination optics may be characterized as The body appears as a fine structure in the detected beam shape at the detector. The small changes in the beam position on the illumination optics correspond to the position of the beam on the slit. The position of the microstructure is monitored to determine the position of the sharp corner caused by the slit. This is confirmed by the error in the tilt of the optical elements.

[0082] In another aspect, the measurement quality and performance of the metrology system can be evaluated by measuring the zeroth order beam. In some examples, the measurement quality and performance estimates described above are used to control the is provided as an input to a feedback controller (e.g., computer system 130). The feedback controller communicates the control command to the measurement system. A change in the state of one or more elements of a measurement system that improves the quality and performance of the system. It becomes.

[0083] In some examples, a control command is provided to the illumination source. In response, The electrical conditions include probed spot size and shape, illumination power, spot offset, incident It is adjusted to change the corners, etc.

[0084] In some examples, the control command may include controlling the location of one or more optical elements of the measurement system. In response, one or more positioning devices are provided to control The device changes the position / orientation of one or more optical elements to adjust the angle of incidence, the relationship between the illumination source and the illumination optics. Focal length between the beam, beam positioning, and optical elements to minimize the effects of surface roughness Adjust the location of the beam spot on the image, etc.

[0085] In general, the measurement quality and performance estimation and control described herein are based on the beam diameter. It can be performed with or without a target in the path.

[0086] In another embodiment, full beam X-ray scatterometry measurements provide sufficient resolution and consistency. The full depth of the high aspect ratio structures is achieved over a range of incidence angles providing Characterize through.

[0087] Measurement of the intensity of diffracted radiation as a function of the angle of incidence of X-rays relative to the normal to the surface of the wafer. The information contained in the multiple diffraction orders is used to estimate the parameters of each model considered. Therefore, X-ray scattering yield estimates are subject to small errors and and yielding parameter values ​​of interest with reduced parameter correlation.

[0088] In some embodiments, the X-ray detector 116 is in the same atmospheric environment as the workpiece 101 (e.g. However, in some embodiments, the specimen 10 may be maintained in a vacuum (e.g., a gas purged environment). The distance between 1 and the X-ray detector 116 is very long, so that environmental disturbances (e.g., turbulence) are not detected. Therefore, in some embodiments, one of the X-ray detectors At least one of the vacuum windows is a local vacuum window separated from the workpiece (e.g., workpiece 101). Maintained in the environment.

[0089] Similarly, in some embodiments, the X-ray radiation source 110, the radiation optics 115, or Both of them are maintained in the same atmospheric environment (eg, a gas purged environment) as the specimen 101 . However, in some embodiments, the light between the X-ray radiation source 110 and the radiation optics 115 may be The length of the optical path between the illumination optics 115 and the workpiece 101 is long. However, environmental disturbances (e.g., turbulence) can impart noise to the illumination beam. In this embodiment, the X-ray radiation source, the radiation optics 115, or both, are secured to the vacuum window. It is maintained in a local vacuum environment, isolated from the work piece (eg, work piece 101).

[0090] FIG. 8 illustrates, in one embodiment, a system including an X-ray radiation source 110 and radiation optics 115. 1 shows a vacuum chamber 160, as well as a vacuum chamber 163 containing an X-ray detector 116. In a preferred embodiment, the vacuum chamber 160 accommodates the X-ray radiation source 110 and the workpiece 10. 1, the vacuum chamber 163 includes many parts of the optical path between the specimen 101 and the X-ray detector. The vacuum chamber 160 and the vacuum chamber 116 are connected to each other. The openings of the vacuum chamber 163 are covered with vacuum windows 161 and 164, respectively. and 164 may be made of any suitable material that is substantially transparent to X-ray radiation (e.g., beryllium). ) as the illumination beam 117 propagates towards the work piece 101. After interacting with the specimen 101, the scattered X-ray radiation 125 passes through the vacuum window 161. 164, enters the vacuum chamber 163 and impinges on the X-ray detector 116. The environment 162 is preferably configured within the vacuum chamber 16 to minimize interference with the illumination beam 117. 0 and a suitable vacuum environment 165 provides minimal interference with the scattered X-ray radiation 125. The preferred vacuum environment may be any suitable vacuum chamber 163 to minimize Any suitable purged environment, including a vacuum of any level, an inert gas (e.g., helium), or or any combination thereof. In this way, as many beam paths as possible It is located in a vacuum to maximize light flux and minimize disruption.

[0091] In some embodiments, the entire optical system, including the specimen 101, is maintained in a vacuum. However, in general, the costs associated with maintaining the specimen 101 in a vacuum are , high due to the complexity associated with constructing the specimen positioning system 140.

[0092] In yet another embodiment, the computer system 130 may be configured to calculate the structure of the measured specimen. Structural model (e.g. exterior model, material model, or combination of exterior model and material model) (a) generating a shape parameter from the structural model, the shape parameter including at least one shape parameter from the structural model; configured to generate a response model for full beam X-ray scatterometry, Comparison of measured X-ray scatterometry data with the response model of full-beam X-ray scatterometry A fitting analysis is performed to determine the parameter values ​​of at least one specimen. The analysis engine analyzes the signals from the simulated full-beam X-ray scatterometry. The signal is used to compare with the measured data, thereby determining the shape and electrical properties of the sample. In the embodiment shown in FIG. The data system 130 is configured as a model building and analysis engine as described herein. Configured to perform model building and analysis functions.

[0093] FIG. 9 illustrates an exemplary model building and 9 illustrates an analysis engine 150. As shown in FIG. 150 is a structural model construction module that generates a structural model 152 of the measured structure of the specimen. In some embodiments, the structural model 152 includes a material characteristic of the specimen. The structural model 152 is a response function construction module for full-beam X-ray scatterometry. The response function for full beam X-ray scatterometry is The construction module 153 calculates the full beam X Generate a line scatterometry response function model 155. In some examples, The response function model for beam X-ray scatterometry 155 is the X-ray formation factor,

number

number

[0094] In some instances, the fit of the modeled data to the experimental data is such that the chi-squared value is maximized. This is achieved by minimizing the amount of scattering that occurs during full-beam X-ray scatterometry measurements. So, the chi-square value is

number

number

number

[0095] Equation (4) assumes that the uncertainties associated with different channels are uncorrelated. In instances where the uncertainties associated with different channels are correlated, the covariance between the uncertainties In these examples, full beam X-ray scatterometry measurements are performed. The chi-square value for a given

number

[0096] In some examples, the conformance analysis module 157 performs full beam X-ray scatterometry. Fitting of full-beam X-ray scatterometry measurement data126 using a linear response model155 A composite analysis is performed to determine a parameter value for at least one sample piece. In some instances,

number

[0097] As explained above, the fit of the full beam X-ray scatterometry data is a chi-squared However, in general, full-beam X-ray scatterometry data The adaptation of the data may be achieved by other functions.

[0098] The fitting of full beam X-ray scatterometry metrology data is done by adjusting the sensitivity to the geometry and / or Any type of full beam X-ray scatterometry technique that provides Advantageously, the parameters of the specimen are determined by the beam of the specimen in full beam X-ray scatterometry. Deterministic (e.g., CD, SWA, etc.) as long as appropriate models representing system interactions are used. or it may be statistical (eg, the rms height of the sidewall roughness, the roughness correlation length, etc.).

[0099] Generally, the computer system 130 performs real-time critical dimensioning (RTCD). configured to access model parameters in real time using The computer system 130 is configured to: Access a library of pre-calculated models to determine parameter values ​​for Typically, some form of CD engine is used to determine the assigned CD of a specimen. The difference between the parameter and the CD parameter associated with the measured specimen can be evaluated. An exemplary method and system for calculating parameter values ​​of a specimen includes: No. 6,313,533, filed on Nov. 2, 2010 by KLA-Tencor Corp., the entire disclosure of which is incorporated herein by reference. As described in issued U.S. Patent No. 7,826,071.

[0100] In some examples, the model building and analysis engine 150 may include a feed side- By any combination of the feedforward, parallel, and parallel analyses, Improve the accuracy of the measured parameters. Feed sideways analysis is performed on the same specimen. Taking multiple data sets in different regions and determining a common Refers to passing parameters to a second data set for analysis. The analysis involves taking data sets for different specimens and copying common parameters step by step. Using a feed-forward approach of accurate parameters in the Parallel analysis refers to passing all the data sets to a single analysis, where at least one common parameter is combined during the fit. Apply nonlinear fitting measures in parallel or simultaneously to multiple data sets being analyzed This refers to the following.

[0101] Multiple tools and structural analysis include regression, lookup tables (i.e., "library" fits), and Based on other fitting procedures for multiple data sets, feedforward analysis, feedside Refers to multi-way analysis, or parallel analysis. The law and system is incorporated herein by reference in its entirety on January 13, 2009 in KL As described in U.S. Patent No. 7,478,019 issued to A-Tencor Corp. is.

[0102] In another embodiment, the metrology tool 100 may include the beam control functions described herein. A computer system (e.g., computer system 130) configured to implement In the embodiment shown in FIG. 1, the computer system 130 includes the intensity, divergence, spread, Any illumination can be selected, including pot size, polarization, dispersion, and positioning of the incoming illumination beam 117. The beam controller is configured as a beam controller operable to control the beam characteristics.

[0103] As shown in FIG. 1, a computer system 130 is communicatively coupled to the detector 116. The computer system 130 receives the measurement data 126 from the detector 116. In one example, the measurement data 126 is configured as a measured response of the specimen (i.e., The distribution of the response measured on the surface of the detector 116 includes a representation of the intensity of the diffraction orders. Based on this, the incident position and area of ​​the illumination beam 117 on the workpiece 101 is calculated by a computer system. In one example, the pattern recognition technology is used to determine the The irradiation on the specimen 101 is applied by the stem 130 based on the measured data 126. Determine the location and area of ​​incidence of the beam 117. In some examples, a computer system The stem 130 is used to select the desired illumination wavelength and to redirect and reshape the illumination beam 117. 13. A command signal 136 is communicated to the illumination optics 115 to illuminate the incident The illumination beam 117 reaches the workpiece 101 at a desired location and angle. In some examples, the computer system 130 determines the position and orientation of the specimen 101. A command signal is communicated to the wafer positioning system 140 to determine the position of the wafer. The incident illumination beam 117 is oriented at a desired location and angle relative to the workpiece 101. In some other examples, the computer system 130 may determine the desired illumination wavelength. and sending command signals 137 to redirect and reshape the illumination beam 117. In communication with the X-ray source 110, an incident beam of radiation 117 is directed toward the workpiece 101. to arrive at the desired location and angular orientation.

[0104] In some embodiments, the coordinate system 146 shown in FIG. It is desirable to perform measurements at different orientations represented by rotation. , improving the accuracy and precision of the measured parameters and reducing the data set available for analysis. By expanding the number and variety to include a variety of large angles and out of plane orientations , reducing correlations between parameters. With deeper and more diverse data sets, By measuring the parameters of only one piece, the correlation between the parameters can be reduced and the measurement accuracy can be improved. For example, in the vertical direction, full-beam X-ray scatterometry improves the The critical dimensions of the feature can be determined, but are highly sensitive to the sidewall angle and height of the feature. However, by collecting measurements over a wide range of out-of-plane angular positions, The sidewall angle and height of the feature can be determined.

[0105] As shown in FIG. 1, the metrology tool 100 is oriented at an out-of-plane angle relative to the scatterometer. Both the alignment of the sample piece 101 and the orientation of the sample piece 101 can be achieved over a wide range of In other words, the sample piece positioning system 140 is configured to The mounting system 140 has one or more rotation axes aligned in-plane with the surface of the specimen 101. The specimen 101 is configured to rotate around a wide range of angles. In an embodiment, the specimen positioning system 140 is positioned in-plane with the surface of the specimen 101. Rotate the specimen 101 within a range of at least 90° around one or more aligned rotation axes. In some embodiments, the specimen positioning system is configured to rotate the specimen. At least 60° around one or more rotational axes aligned in-plane with the surface of the piece of material 101 In some other embodiments, the sample piece 101 is rotated within a range of 10°. The specimen positioning system may include one or more sensors aligned in-plane with the surface of the specimen 101. and configured to rotate the specimen 101 within a range of at least 1° around the axis of rotation of the In this way, angle resolved measurements of the workpiece 101 can be made at any number of points on the surface of the workpiece 101. The measurements are collected by the measurement system 100. In one example, The system 130 transmits a command signal to a workpiece positioning device 132 indicating the desired workpiece 101 position. In response, the motion controller 145 communicates with the motion controller 145 of the system 140. To achieve the desired positioning of the specimen 101, various configurations of the specimen positioning system 140 are The actuator generates a command signal.

[0106] By way of non-limiting example, as shown in FIG. 1, the specimen positioning system 140 includes an edge gripping chamfer. 141 to securely mount the specimen 101 to the specimen positioning system 140. The rotation actuator 142 rotates the edge-gripping chuck 141 and the attached specimen 101. is configured to rotate relative to the perimeter frame 143. In the illustrated embodiment, The rotation actuator 142 rotates the workpiece 101 around the X-axis of the coordinate system 146 shown in FIG. As shown in FIG. 1, the rotation of the specimen 101 around the Z axis is Rotation around the X-axis and Y-axis (not shown) is the in-plane rotation of the sample piece 101. 1, effectively rotating the surface of the workpiece relative to the measurement elements of the metrology system 100. Although not shown, a second rotary actuator rotates the sample piece 101 in the Y-axis direction. The linear actuator 144 is configured to rotate the perimeter frame 143 about the A separate linear actuator (not shown) is configured to translate the perimeter flange in the X direction. The frame 143 is configured to translate in the Y direction. In this way, All of the points can be measured over a range of out-of-plane angular positions. In this state, the location of the sample piece 101 is in the range of -45° to +4° with respect to the vertical direction of the sample piece 101. It is measured over several angular increments within a range of 5°.

[0107] Generally, the specimen positioning system 140 is configured to provide the desired linear and angular positioning capabilities. To achieve this, a goniometer stage, a hexapod stage, an angle The actuator may include any suitable combination of mechanical elements, including a linear stage, a phase shift stage, and a step stage.

[0108] In another embodiment, an initial estimate of one or more parameter values ​​of the subject is determined by measuring the measurement objective. Full beam X-ray scatterometry performed with a single orientation of the incident X-ray beam relative to The initial estimate is determined based on measurements. Measurement data collected from full beam X-ray scatterometry measurements in the axial direction were used to This method is performed for the regression of a constant model. This refined estimate can be determined with relatively little computational effort and can then be applied to regressions across larger data sets. By using the metric as a starting point, accurate estimation of the parameters of interest can be achieved with a small total It can be obtained by calculation.

[0109] In another embodiment, full beam X-ray scatterometry measurement data is used to detect Based on the measured intensities of the selected diffraction orders, an image of the measured structure is generated. In an embodiment, a response function model for full beam X-ray scatterometry is derived and generally This model represents the scattering of a mesh of typical electron density. To enforce continuity and scattered edges on the other hand, we modeled dense regions in this mesh. Confining the focal plane results in a three-dimensional image of the sample.

[0110] Contour-based, model-based, parametric inversion for full-beam X-ray scatterometry Although preferred for critical dimension (CD) metrology based on the measurement of the lattice plane, the same full-beam X-ray scatterometry is used. The sample map generated from the bird measurement data shows that the measured sample corresponds to the assumed external model. This is useful for identifying and correcting model errors when the model deviates from the

[0111] In some instances, the images may be representative of the contours, models, or other images of the same scatterometry measurement data. The structural features estimated by the model-based parametric inversion are compared with those estimated by the model-based parametric inversion. is used to update the contour model of the measured structure and improve measurement performance. The ability to converge to accurate parametric measurement models is essential for controlling, monitoring, and This is particularly important when making measurements to detect faults in manufacturing processes.

[0112] In some instances, the image may include electron density, absorption coefficient, complex refractive index, or a combination of these materials. A two-dimensional (2-D) map of a combination of features. In some examples, the image is Three-dimensional (3-D) characterization of electron density, absorption coefficient, complex refractive index, or a combination of these material properties. D) A map. The map is generated using relatively few physical constraints. Examples include critical dimension (CD), sidewall angle (SWA), overlay, edge position error, One or more parameters of interest, such as pitch walk, are then directly estimated from the resulting maps. In some other instances, the geometry or material of the sample may be inconsistent with the model-based CD measurements. outside the range of assumed values ​​contemplated by the parametric structural model used to determine If the deviations are large, the map is useful for finding and correcting defects in wafer processing. In the example, a map and a parametric structural model according to the measured parameters are used. Differences from the expected structural rendering are reported through updates to the parametric structural model and and to improve the measurement performance thereof. Further details are set forth in the entire contents of this application. No. 2015 / 0300965, which is incorporated by reference. Further details are described in U.S. Patent Application Publication No. 2015 / 013363, the entire contents of which are incorporated herein by reference. This is described in No. 0117610.

[0113] In another embodiment, the model building and analysis engine 150 performs X-ray and optical metrology analysis. In some cases, optical simulation is used to generate a model that combines For example, the calculation can be done by solving Maxwell's equations to determine the reflectance of different polarized light, ellipsometry, It is based on Rigorous Coupled Wave Analysis (RCWA) to calculate the optical signals parameters, such as phase changes.

[0114] The values ​​of one or more parameters of interest are used to detect X-ray diffraction orders at a number of different angles of incidence. Combined fitting analysis of the combined intensity and combined exomorphically parameterized response models The light intensity is determined based on the light intensity detected by the optical metrology tool. The optical measurement tool is a system 100 and a system 110 shown in Figs. 1 and 2, respectively. 200, may or may not be mechanically integrated with an X-ray metrology system. For more details, see U.S. Patent Application Publication No. 2010 / 013991, the contents of each of which are incorporated herein by reference in their entirety. No. 4 / 0019097 and U.S. Patent Application Publication No. 2013 / 0304424. is.

[0115] As described herein, full beam X-ray scatterometry measurements are performed on semiconductor wafers. Multiple orientations of the X-ray beam with respect to the vertical surface of the By rotating the wafer 101 relative to the beam by any two angles, or vice versa, In one example, the orientation can be expressed relative to a coordinate system fixed to the wafer. FIG. 11 shows X-ray radiation incident on a wafer 101 at specific orientations indicated by angles φ and θ. The coordinate frame XYZ is fixed to the measurement system, and the coordinate frame X'Y'Z' is It is fixed to the wafer 101. Z is aligned to the axis perpendicular to the surface of the wafer 101. X and Y lie in a plane aligned with the surface of the wafer 101. Similarly, Z′ lies in the The X′ and Y′ axes are aligned along the axis perpendicular to the surface of the wafer 101. As shown in FIG. 11, the X-ray radiation beam 117 is in a plane aligned with X'Z' The angle φ is the angle of the X-ray radiation beam 117 with respect to the normal of the wafer in the X'Z' plane. Furthermore, the angle θ represents the orientation of the X'Z' plane relative to the XZ plane. Together, φ and φ uniquely define the orientation of the X-ray illumination beam 117 relative to the surface of the wafer 101. In this example, the X-ray irradiation beam is oriented relative to the surface of the wafer 101. 1 by rotation about an axis perpendicular to the surface of wafer 101 (i.e., the Z axis) and The rotation is expressed by a rotation about the axis aligned with the In this example, the orientation of the X-ray radiation beam relative to the surface of the wafer 101 is as follows, with reference to FIG. As described, rotation about a first axis aligned with the surface of the wafer 101; and rotation about another axis aligned with the surface of the wafer 101 and perpendicular to the first axis; It is represented by:

[0116] In some embodiments, full beam X-ray scatterometry as described herein may be used. The metrology target characterized by the measurement of the scribe line of the wafer being measured is In these embodiments, the metrology target fits within the width of the scribe line. In some examples, the scribe line width is 80 microns. In some instances, the width of the scribe lines is less than 50 microns. Generally, the width of the scribe lines used in semiconductor manufacturing is small. The trend is for the

[0117] In some embodiments, full beam X-ray scatterometry as described herein may be used. The metrology target characterized by the measurement of the 3D is located within the active die area of ​​the wafer being measured. A semiconductor integrated circuit is a device that is part of a functional integrated circuit (e.g., memory, image sensor, logic element, etc.).

[0118] Typically, to minimize contaminating signals from structures surrounding the measurement target being measured, The spot size of the illumination beam is preferably closely matched to the lateral dimensions of the measurement target being measured. In some embodiments, the measurement target being measured is less than 70 microns in either lateral dimension. In some embodiments, the measurement target during measurement is either The lateral dimensions of the ion exchange membrane are also less than 50 micrometers. The measurement target has no lateral dimensions less than 40 micrometers. In this case, the measurement target being measured has no lateral dimensions smaller than 10 micrometers. In some embodiments, the metrology target being measured has a total height ( or equivalently, depth). The measurement target being measured must have a total height greater than 2 micrometers (or equivalent). It is characterized by the depth.

[0119] Generally, the measurement target is designed to have a maximum height dimension (i.e., the dimension perpendicular to the wafer surface) of the measurement target. It is defined as the maximum lateral dimension (i.e., the dimension aligned with the wafer surface) divided by the maximum lateral dimension (i.e., the dimension aligned with the wafer surface). In some embodiments, the aspect ratio of the measurement being performed is The measurement target has an aspect ratio of at least 20. The target has an aspect ratio of at least 40.

[0120] 10A-10C are diagrams illustrating a typical 3D flash image that may be measured using the methods described herein. 1A and 1B are isometric, top, and cross-sectional views, respectively, of a memory device 190. The total height (or equivalently, depth) of the element 190 is in the range of 1 to 7 micrometers. The memory device 190 is a vertically fabricated device. The directly fabricated elements essentially rotate the traditional flat memory elements by 90 degrees, Orient the gates and cell strings vertically (perpendicular to the wafer surface). To provide this, many alternating layers of different materials are deposited on the wafer. To perform well to depths of several microns for structures less than 100 nanometers in length As a result, aspect ratios of 25:1 or 50:1 are uncommon. do not have.

[0121] 12 is a top view of an array of high aspect ratio hole structures 310. As shown in FIG. The array of hole structures is formed on faces 311, 312, 313, and 314 (which are inward and outward from the view). In some embodiments, the pattern is most densely patterned along the inner surface of the substrate (extending toward the substrate and outward). Measurements of the high aspect ratio structures described herein are performed on arrays of high aspect ratio structures. The X-ray illumination incident on the surface of the wafer being measured lies in the plane where the X-rays are most densely patterned. In the example shown in FIG. 12, X-ray irradiation is preferably performed in the direction of the X-ray beam. , in faces 311 and 312, where the array of hole structures is most densely patterned; and Preferably, an array of hole structures 310 in 313 and 314 is provided.

[0122] FIG. 13A is a side view of a typical high aspect ratio hole structure 320. FIG. FIG. 13C is a side view of the inclined hole structure 321. The degree of inclination increases progressively with depth. FIG. 3 is a side view of a progressively inclined hole structure 322 that increases the and 322 are undesirable. In some embodiments, hole structures 321 and 322 Similar hole structures were characterized by full-beam X-ray scatterometry measurements as described herein. In one example, the hole structure 321 is characterized by a tilt angle parameter α. Furthermore, the X-ray radiation beam 117 is oriented perpendicular to the X-ray source as described, for example, with reference to FIG. The hole structure 321 is provided at an angle φ with respect to the surface, and at an opposite angle -φ. In morphology, the difference in the measured T-SAX signal appears in these two irradiation cases. , provides sufficient signal information to accurately estimate the tilt angle α.

[0123] In another example, the hole structure 322 has several inclination angle parameters α1, α2, and Similarly, the X-ray radiation beam 117 is piecewise characterized by α3, see e.g., FIG. As described above with respect to the vertical surface, the hole structure 322 is formed at an angle φ and an opposite angle −φ. In some embodiments, the measured The difference in the T-SAX signal is used to accurately estimate the tilt angles α1, α2, and α3. Provide sufficient signal information.

[0124] The various steps described throughout this disclosure may be implemented using a single computer system 130 or a separate computer system. It should be understood that the method may instead be implemented by multiple computer systems 130. Additionally, other subsystems of the system 100, such as the specimen positioning system 140, A computer system suitable for carrying out at least some of the steps described herein. Therefore, the foregoing description should not be construed as limiting the present invention. Further, the one or more computer systems 130 may be It may be configured to perform any other step of any of the method embodiments described.

[0125] Further, the computer system 130 may be configured to detect the presence of the detector 1 in any manner known in the art. 16 and illumination optics 115. For example, one or more The data system 130 is associated with each of the detectors 116 and the illumination optics 115. In another example, the detector 116 and the illuminating light may be connected to a computer system. Any of the optical elements 115 may be a single computer connected to a computer system 130. The system may be directly controlled by the computer system.

[0126] The computer system 130 may include wireline and / or wireless portions. The transmission medium allows the subsystems of the system (e.g., detector 116 and illumination optics 1 15) In this manner, the transmission medium may be used to transmit and receive data between computer system 130 and other components of system 100. It may serve as a data link between the subsystems.

[0127] The computer system 130 of the metrology system 100 may be configured to The transmission of data or information (e.g., measurement data) from other systems by a transmission medium that may include a wireless portion. to receive and / or obtain (e.g., measurement results, modeling inputs, modeling results, etc.) In this manner, the transmission medium may be configured to transmit and receive data between the computer system 130 and other systems. (e.g., the on-board memory of the measurement system 100, an external memory, or an external system) For example, the computer system 130 may serve as a data link between the Measurement data (e.g., For example, any of the detectors 116 may be configured to receive a spectrometer signal 126. The spectroscopic results obtained by the above steps are stored in a permanent or semi-permanent memory (e.g., memory 132 or 133). 80). The measurement results can then be stored in the on-board memory or in an external memory system. Further, the computer system 130 may receive the information from the computer system 130 via a transmission medium. The data may be transmitted to other systems. For example, the data may be determined by the computer system 130. The parameter values ​​170 of the sample piece are stored in a permanent or semi-permanent memory (e.g., a memory 180), the measurement results can then be transmitted to another system.

[0128] Computer system 130 may include, but is not limited to, a personal computer system. systems, mainframe computer systems, workstations, image computers, This may include a column processor, or any other device known in the art. In general, the term "computer system" refers to one or more processors that execute instructions from a memory medium. The term "device" may be broadly defined to include any device having a processor.

[0129] Program instructions 134 for implementing the methods described herein include wires, cables, , or a wireless transmission link. Thus, the program instructions stored in memory 132 are transmitted to processor 1 via bus 133. 31. The program instructions 134 may be stored on a computer readable medium (e.g., Exemplary computer-readable media include a read-only memory 132. Examples include: utility memory, random access memory, magnetic or optical disks, or magnetic tapes. Can be obtained.

[0130] In some embodiments, the scatterometry analyses described herein are performed during the fabrication process. Examples of fabrication process tools include, but are not limited to, , lithographic exposure tools, film deposition tools, implant tools, and etching tools. Thus, the results of full beam X-ray scatterometry analysis can be used to In one example, the collected data from one or more targets is used to control the process. Full beam X-ray scatterometry measurement data is sent to the fabrication process tool. The beam X-ray scatterometry measurement data is analyzed as described herein. The results are used to adjust the operation of a fabrication process tool.

[0131] The scatterometry measurements described herein can be used to characterize various semiconductor structures. Exemplary structures include, but are not limited to, FinFETs and nanowire Or low-dimensional structures such as graphene, structures of 10 nm or less, lithography structures, and Through-substrate via (TSV) and DRAM, DRAM 4F2, FLASH, MRAM, high as Exemplary structural features include memory structures such as limited aspect ratio memory structures. The following are not fixed: line edge roughness, line width roughness, hole size, hole density, sidewall angle, profile The geometric parameters such as the size, critical dimension, and pitch, as well as the electron density, composition, grain structure, morphology, and and material parameters such as structure, flow stress, strain, and elemental identification.

[0132] FIG. 14 illustrates a method suitable for implementation by the measurement systems 100 and 200 of the present invention. In one embodiment, the data processing block of the method 300 is a computer system. Pre-programmed algorithms executed by one or more processors of the system 130 It will be understood that the measurement system 100 and Although the present invention is presented in conjunction with the measurement systems 100 and 200, the specific construction aspects of the measurement systems 100 and 200 are not intended to be limiting. It is understood herein that the terms used herein do not represent a definition, but are merely exemplary.

[0133] In block 301, a measurement target formed on the wafer surface is irradiated with a focused beam of X-ray radiation. The beam is illuminated at multiple different orientations towards the measurement target.

[0134] In block 302, radiation scattered from a measurement target in response to an incident beam of X-ray radiation is detected. The intensity associated with the zero diffraction order of the radioactive material and the intensity associated with the higher diffraction orders The intensity is detected simultaneously in each direction.

[0135] In block 303, the parameter values ​​of the object associated with the model of the measurement target are , is determined based on the detected intensities of the diffraction orders at multiple orientations.

[0136] As described herein, the term "critical dimension" refers to any critical dimension of a structure (e.g., a critical dimension dimension, mid-critical dimension, top critical dimension, sidewall angle, lattice height, etc.), any two or more structures Critical dimensions between (e.g., the distance between two structures) and the location between two or more structures This includes misalignment (e.g., overlay misalignment between overlaid lattice structures). can include three-dimensional structures, patterned structures, overlay structures, and the like.

[0137] As described herein, the term "critical dimension application" or "critical dimension measurement application" refers to any critical dimension application. Includes boundary dimension measurements.

[0138] As described herein, the term "metrology system" refers to a system for performing critical dimension and overlay metrology applications. At least a portion of the specimen was used to characterize the specimen in any manner, including for use in However, such technical terms may be used interchangeably with the terms described herein. It is not intended to limit the scope of the "measurement system." Furthermore, the measurement system described in this specification The system is suitable for measurements on patterned and / or unpatterned wafers. The metrology system can be configured for LED inspection tools, edge inspection tools, backside inspection tools, and tool, macro inspection tool, or multi-mode inspection tool (one or more platforms) (including data from a simultaneous The measuring device may be configured as any suitable metrology or inspection tool.

[0139] Various embodiments are directed to a semiconductor processing system (e.g., The term "sample" is used herein for a sample inspection system or a lithography system. A "piece" as used herein refers to a wafer, reticle, or other object that has been processed (e.g., a wafer, a reticle, or a wafer) by methods known in the art. It is used to refer to any other sample that may be printed or inspected for defects.

[0140] As used herein, the term "wafer" generally refers to a wafer of semiconductor or non-semiconductor material. Examples include, but are not limited to, single crystal silicon, gallium arsenide, and and indium phosphide. Such substrates are commonly found in semiconductor fabrication facilities. In some cases, the wafer may include only the substrate. Alternatively, the wafer may be a wafer of different materials formed on a substrate. One or more layers formed on a wafer may be "patterned." For example, the wafer may be patterned with a repeatable pattern. It may include multiple dies having features.

[0141] A "reticle" may be a reticle at any stage in the reticle fabrication process; or a finished reticle which may or may not be shipped for use in a semiconductor fabrication facility. The reticle or "mask" is generally a substantially transparent material having a The term "substrate" refers to a substrate having substantially opaque areas arranged in a pattern. For example, the substrate may include a glass material such as amorphous SiO2. During the exposure step of the process, a resist cover wafer may be disposed over the The pattern on the reticle can be transferred into the resist.

[0142] One or more layers formed on a wafer may be patterned or unpatterned. For example, a wafer may include multiple dies, each having a repeatable pattern feature. The construction and processing of such layers of materials may ultimately result in a completed device. Many different types of devices may be formed on a wafer, and the term wafer as used herein. Wafer is intended to encompass a wafer upon which any type of device known in the art may be fabricated. It is intended that

[0143] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, or The method may be implemented in software, firmware, or any combination thereof. When implemented, the functions may be represented as one or more instructions or The computer-readable medium may be stored or transmitted as a program or code. refers to computer storage media and the transfer of computer programs from one location to another. The term storage media includes both general-purpose or non-standard storage media and communication media including any medium facilitating the transmission of information. It may be any available medium that can be accessed by a special purpose computer. Such computer readable media may include, but is not limited to, RAM, ROM, EEPROM, CD-ROM, or other optical disk storage devices, magnetic disk storage devices or other magnetic storage device, or a desired program code means for storing instructions or data It can be used to execute or store data in the form of a data structure, and can be used on general-purpose or special-purpose computers. computer, or any other medium accessible by a general-purpose or special-purpose processor. Further, any connection may be qualified as a computer-readable medium. For example, the software can be used to connect coaxial cables, fiber optic cables, Pair, Digital Subscriber Line (DSL), or infrared, radio, and microwave transmitted from a website, server, or other remote source using wireless technology. If you have a coaxial cable, fiber optic cable, twisted pair, DSL, or infrared, Included in the definition of medium are wired and wireless technologies such as microwave. The disks (disk and disc) referred to are compact disks (CDs), laser disks, disk, XRF disk, digital versatile disk (DVD), floppy disk Disk and Blu-ray Disc (registered trademark). Here, disk means Normally, data is reproduced magnetically, while discs read data optically using a laser. Combinations of the above are also included within the scope of computer-readable media.

[0144] Although certain specific embodiments are described above for instructional purposes, the teachings of this patent document are generally The present invention has general applicability and is not limited to the specific embodiments described above. Thus, various modifications, adaptations, and combinations of the various features of the described embodiments are within the spirit and scope of the present invention. It is contemplated that modifications may be made without departing from the scope of the invention as set forth in the claims.

Claims

1. an X-ray radiation source configured to generate a quantity of X-ray radiation; The amount of X-ray radiation is used to measure the wafer surface at a number of different orientations relative to the measurement target. an x-ray projection optics subsystem configured to project the measurement target formed on the x-ray projection optics subsystem; and, a quantity scattered from the measurement target in response to the impinging X-ray radiation in each orientation; of radiation, the intensity associated with the zeroth diffraction order and the intensity associated with the higher diffraction orders A CD-SAXS X-ray detector configured to simultaneously detect multiple intensities, The zero diffraction order and the higher diffraction orders are at least one of the plurality of different orientations. an X-ray detector overlapping said X-ray detector; The measurement objective is based on the detected intensities of the diffraction orders at the plurality of different orientations. A computer configured to determine parameter values ​​of an object associated with a model of the object. Data system and Equipped with The computer system includes: Based on the measured beam profile of the zero diffraction order, The metrology system is further configured to determine a model of the beam profile.

2. an X-ray radiation source configured to generate a quantity of X-ray radiation; The amount of X-ray radiation is used to measure the wafer surface at a number of different orientations relative to the measurement target. an x-ray projection optics subsystem configured to project the measurement target formed on the x-ray projection optics subsystem; and, a quantity scattered from the measurement target in response to the impinging X-ray radiation in each orientation; of radiation, the intensity associated with the zeroth diffraction order and the intensity associated with the higher diffraction orders A CD-SAXS X-ray detector configured to simultaneously detect multiple intensities, The zero diffraction order and the higher diffraction orders are at least one of the plurality of different orientations. an X-ray detector overlapping said X-ray detector; The measurement objective is based on the detected intensities of the diffraction orders at the plurality of different orientations. A computer configured to determine parameter values ​​of an object associated with a model of the object. Data system and Equipped with The computer system includes: The detected intensity of the zero diffraction order is used to detect the detected intensity of the higher diffraction orders. By dividing the intensity, the intensity of the higher diffraction orders is divided by the intensity of the zero diffraction order. The measurement system is further configured to estimate the intensity of the measured signal.

3. The measurement system according to claim 1 or 2, The model of the measurement target is a measurement of the X-ray radiation from the X-ray radiation source to the X-ray detector. A measurement system that contains values ​​of the divergence of morphisms.

4. The measurement system according to claim 1 or 2, The computer system includes: Based on the characteristics of the detected zero diffraction order, an indication of measurement quality and performance is determined. A measurement system further comprising:

5. 5. The measurement system according to claim 4, The indication of measurement quality and performance may include the alignment of the X-ray detector to the axis of the illuminating X-ray radiation. and a brightness of the X-ray radiation source. alignment of the elements of the measurement system, either the Tem.

6. 5. The measurement system according to claim 4, The computer system includes: A command is issued to adjust the metrology system based on the indication of measurement quality and performance. a measurement system further configured to communicate a calibration signal to an element of the measurement system.

7. The measurement system according to claim 1 or 2, the photosensitive volume of the X-ray detector being made of cadmium telluride, germanium, gallium arsenide, or a measurement system including any combination of these.

8. The measurement system according to claim 1 or 2, A metrology system in which the measurement target includes one or more high aspect ratio structures.

9. 9. The measurement system according to claim 8, The one or more high aspect ratio structures may provide spin-transfer torque random access. STT-RAM, Three-dimensional NAND memory (3D-NAND), Dynamic Random Access Memory (SRAM) Dynamic Random Access Memory (DRAM), Three-dimensional Flash Memory (3D-FLASH (registered trademark) ), resistive random access memory (Re-RAMPC), and phase change random access The measurement system may be either a PC-RAM or a

10. an X-ray radiation source configured to generate a quantity of X-ray radiation; The amount of X-ray radiation is used to measure the wafer surface at a number of different orientations relative to the measurement target. an x-ray projection optics subsystem configured to project the measurement target formed on the x-ray projection optics subsystem; and, a quantity scattered from the measurement target in response to the impinging X-ray radiation in each orientation; of radiation, the intensity associated with the zeroth diffraction order and the intensity associated with the higher diffraction orders a CD-SAXS X-ray detector configured to simultaneously detect the intensities of the two beams; The detected intensities of the zeroth diffraction order and the higher based on a regression of a model of the measurement target with the detected intensities of the diffraction orders. A computer configured to determine parameter values ​​of an object associated with the model of the object. Computer system and Equipped with The computer system includes: Based on the measured beam profile of the zero diffraction order, Further configured to determine a model of the beam profile. Measurement system.

11. an X-ray radiation source configured to generate a quantity of X-ray radiation; The amount of X-ray radiation is used to measure the wafer surface at a number of different orientations relative to the measurement target. an x-ray projection optics subsystem configured to project the measurement target formed on the x-ray projection optics subsystem; and, a quantity scattered from the measurement target in response to the impinging X-ray radiation in each orientation; of radiation, the intensity associated with the zeroth diffraction order and the intensity associated with the higher diffraction orders a CD-SAXS X-ray detector configured to simultaneously detect the intensities of the two beams; The detected intensities of the zeroth diffraction order and the higher based on a regression of a model of the measurement target with the detected intensities of the diffraction orders. A computer configured to determine parameter values ​​of an object associated with the model of the object. Computer system and Equipped with The computer system includes: The detected intensity of the zero diffraction order is used to detect the detected intensity of the higher diffraction orders. By dividing the intensity, the intensity of the higher diffraction orders is divided by the intensity of the zero diffraction order. The measurement system is further configured to estimate the intensity of the measured signal.

12. The measurement system according to claim 10 or 11, A metrology system in which the zeroth diffraction order and the higher diffraction orders overlap at the X-ray detector. Hmm.

13. The measurement system according to claim 10 or 11, The model of the measurement target is a measurement of the X-ray radiation from the X-ray radiation source to the X-ray detector. A measurement system that contains values ​​of the divergence of morphisms.

14. The measurement system according to claim 10 or 11, The computer system includes: Based on the characteristics of the detected zero diffraction order, an indication of measurement quality and performance is determined. A measurement system further comprising:

15. The measurement system according to claim 10 or 11, A metrology system in which the measurement target includes one or more high aspect ratio structures.

16. 16. The measurement system of claim 15, The one or more high aspect ratio structures may provide spin-transfer torque random access. STT-RAM, Three-dimensional NAND memory (3D-NAND), Dynamic Random Access Memory (SRAM) Dynamic Random Access Memory (DRAM), Three-dimensional Flash Memory (3D-FLASH (registered trademark) ), resistive random access memory (Re-RAMPC), and phase change random access The measurement system may be either a PC-RAM or a

17. The measurement system according to claim 10 or 11, The computer system performs a generalized full binomial analysis as a mesh of general electron density. a beam X-ray scatterometry response function model for the diffraction order in the plurality of different orientations; a number of the detected intensities, and and determining a multi-dimensional image of the measurement target based on the detected intensities of the orders. The measurement system configured.

18. an X-ray radiation source configured to generate a quantity of X-ray radiation; The amount of X-ray radiation is used to measure the wafer surface at a number of different orientations relative to the measurement target. an x-ray projection optics subsystem configured to project the measurement target formed on the x-ray projection optics subsystem; and, a quantity scattered from the measurement target in response to the impinging X-ray radiation in each orientation; of radiation, the intensity associated with the zeroth diffraction order and the intensity associated with the higher diffraction orders a CD-SAXS X-ray detector configured to simultaneously detect the intensities of the two beams; Based on the measured beam profile of the zero diffraction order, determining a model of a beam profile of the diffraction orders at the plurality of different orientations; a parameter value of the object associated with a model of the measurement target based on the detected intensity; and a computer system configured to determine Equipped with The computer system includes: The detected intensity of the zero diffraction order is used to detect the detected intensity of the higher diffraction orders. By dividing the intensity, the intensity of the higher diffraction orders is divided by the intensity of the zero diffraction order. The measurement system is further configured to estimate the intensity of the measured signal.

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