Spectral elliptical polarization measurement with detector-resolved numerical aperture for deep structure metrology

Abstract

Presented herein are methods and systems for performing spectral elliptical polarization measurements of semiconductor structures with a collection NA resolved at a detector. The collection NA defines a small measurement cartridge size. The NA is distinguished and collected at the detector, so that the measurement sensitivity is remarkably improved. In some examples, the collection NA is subdivided into 50 to 100 sub-ranges at the detector. In some embodiments, a spectral ellipsometer employing angle resolved detection of collected NAs includes a coherent illumination source having a high spectral intensity across a wavelength range from 400 nanometers to 2,500 nanometers. In some embodiments, an illumination beam is scanned over a surface of a sample being measured at a high frequency during measurement. Spectral elliptical polarization measurements with detector-resolved collected NAs enable critical dimension, shape and profile measurements as well as film measurements of deep structures fabricated according to current semiconductor fabrication nodes, as well as those considered to be fabricated at future semiconductor fabrication nodes.

Description

[0001] Cross-reference of related applications

[0002] This patent application claims priority under 35 USC §119 to U.S. Provisional Patent Application Serial No. 63 / 542,100, filed October 3, 2023, entitled “Coherent-SourceAngle-Resolved Spectroscopic Ellipsometry for Deep Structure Metrology in Semiconductor Fabrication,” the subject matter of which is incorporated herein by reference in its entirety. Technical Field

[0003] The described embodiments relate to metrology systems and methods, and more specifically, to improved measurement methods and systems for semiconductor structures. Background Technology

[0004] Semiconductor devices, such as logic and memory devices, are typically fabricated through a sequence of processing steps applicable to the sample. Various features and multiple structural levels of a semiconductor device are formed through these processing steps. For example, photolithography, one of the other processing steps, is a semiconductor fabrication process involving the creation of patterns on a semiconductor wafer. Additional examples of semiconductor fabrication processes include, but are not limited to, chemical mechanical polishing, etching, deposition, and ion implantation. Multiple semiconductor devices can be fabricated on a single semiconductor wafer and then separated into individual semiconductor devices.

[0005] During semiconductor manufacturing processes, metrology is used at various steps to measure defects on wafers to achieve higher yields. Optical metrology offers the potential for high throughput without the risk of sample damage. Several optical metrology-based techniques, including scattering, ellipsometrics, and reflectance measurements, along with associated analytical algorithms, are commonly used to characterize critical dimensions, film thickness, composition, stacking, and other parameters of nanoscale structures.

[0006] Flash memory and dynamic random-access memory (DRAM) architectures are transitioning from two-dimensional floating-gate architectures to fully three-dimensional geometries. In some examples, film stacks and etched structures are extremely deep (e.g., depths of up to 15 micrometers or more) and contain many layers. For example, state-of-the-art NAND memory structures contain 200 to 300 layers and tend to have even more, such as 300 to 1,000 layers. Such high aspect ratio multilayer structures present challenges for film and CD measurements. The ability to measure the critical dimensions that define the shape of the holes and trenches in these structures is crucial for achieving desired performance levels and device yields. Furthermore, many semiconductor architectures employ thick layers of opaque material, such as amorphous carbon layers, tungsten layers, and hard mask layers.

[0007] Many optical techniques suffer from low signal-to-noise ratio (SNR) because only a small fraction of the illumination light can reach the bottom of high aspect ratio features and reflect upwards to the detector. Specifically, illumination light in the vacuum ultraviolet, ultraviolet, visible, and short infrared wavelength ranges (i.e., wavelengths below approximately 1 micrometer) suffers from low SNR, and in some examples, the illumination light does not penetrate the opaque layer sufficiently, resulting in no measurable signal at all. Therefore, many available high-throughput metrology techniques cannot reliably perform CD and film measurements on high aspect ratio structures.

[0008] Critical size, small-angle X-ray scattering (CD-SAXS), normal incidence reflectance measurement, and scattering measurement are being explored as measurement solutions for high aspect ratio structures, but development is still ongoing. Cross-sectional scanning electron microscopy (SEM) is a destructive technique with low throughput, unsuitable for inline metrology. Atomic force microscopy (AFM) has limited capabilities for measuring high aspect ratio structures and has relatively low throughput. CD-SAXS has not yet been proven to achieve the high throughput capabilities required by the semiconductor industry. Model-based infrared reflectance measurement (MBIR) has been used for metrology of high aspect ratio DRAM structures, but this technique lacks the resolution provided by shorter wavelengths, and the measurement spot size is too large for semiconductor metrology. See Gostein et al., application filed March 1, 2006, “Measuring deep-trench structures with model-based IR” (Solid State Technology, Vol. 49, No. 3), which is incorporated herein by reference as if stated in its entirety.

[0009] Spectral reflectance measurement (SR) or a hybrid of SR and interferometry can perform measurements in a small number of process steps in a few specific measurement applications. Unfortunately, these techniques lack the sensitivity required to measure critical dimensions, shape profiles, or film thicknesses in a large number of critical process steps.

[0010] Optical CD metrology currently lacks the ability to measure the detailed profiles of structures with micrometer-level depth and lateral dimensions in relatively small light spots (e.g., less than 70 micrometers, or even more preferably less than 50 micrometers) with high throughput. U.S. Patent No. 8,860,937, which describes an infrared ellipsometry measurement technique suitable for characterizing high aspect ratio structures and is incorporated herein by reference in its entirety, describes a technique that suffers from long measurement times, wavelength stability limitations, and a limited infrared wavelength range during operation, as these techniques are used for measurements across ultraviolet and infrared wavelengths.

[0011] Existing SE-based optical metrology tools are limited in their ability to measure high aspect ratio structures (specifically, 3D NAND with more than 300 layers and 3D NAND with a depth greater than 10 micrometers). Current SE-based optical metrology tools strive to meet three requirements: 1) sufficient spectral resolution, specifically at wavelengths less than 700 nanometers; 2) sufficiently small measurement cell size, e.g., 70 micrometers or less; and 3) sufficient signal strength at long wavelengths, e.g., greater than 700 nanometers.

[0012] Existing SE-based optical metrology tools employ detection at a single collection NA. Generally, a collection NA is implemented using a spectrometer slit in the collection path, which selects light at a single collection NA with respect to one or more nominal incident angles. For example, a single-slit spectrometer selects light at a single collection NA with respect to one nominal incident angle. The selected light is focused onto the detector along a single row of detector pixels or several rows of detector pixels. If several rows of detector pixels are used, the detected intensities of those rows are summed to obtain a single intensity value associated with each column of detectors. Either way, the selected light associated with a single collection NA with respect to a nominal incident angle is focused into a single intensity value associated with each column of detectors. In other words, the detector does not distinguish between a single collection NA defined by the spectrometer slit, and the detected NA is a single collection NA. In another example, the spectrometer slit may contain multiple apertures. Each aperture selects light at a single collection NA with respect to a different nominal incident angle. The light selected by each different slit is focused onto a different region of the detector. However, as described above, the light selected by each different slit is focused along a single row of detector pixels or several rows of detector pixels. Similarly, even in the context of multispectral slit measurements, the detector does not distinguish individual collection NAs defined by each spectrometer slit, and the detected NA is a single collection NA with respect to each nominal incident angle.

[0013] In existing SE-based optical metrology tools for measuring deep structures, a single collection NA must be selected that most closely meets the measurement requirements described above. In one example, a conventional SE measurement system employs a spectrometer slit that transmits light to a detector with an illumination NA approximately one-fifth the size of the illumination NA in a low collection NA measurement context. COLL ~NA ILL The collected NA is / 5). In another example, a conventional SE measurement system employs a spectrometer slit that transmits light to a detector having an illumination NA that is approximately one-twentieth (NA) of the illumination NA in ultra-low collected NA measurement scenarios. COLL ~NA ILL The collection of NA ( / 20)

[0014] Equation (1) graphically illustrates the design criteria for collecting numerical aperture (NA) data to meet the measurement box size requirements of the SE metrology system, where NA... COLL Where NA is the desired collection wavelength, λ is the wavelength of the illumination light under consideration, and B is the wavelength of the light source. NC B is a scaling constant for the cell size associated with the incoherent source, and S is the size of the measurement cell under consideration. Typically, B... NCThe value is approximately 1, and the measurement cell size is 50 micrometers or smaller. Large wavelength ranges are being considered, such as 400 nm to 2,000 nm, 400 nm to 2,500 nm, or even larger.

[0015] (1)

[0016] As described above, the low-collection NA measurement scenario employed in conventional SE measurement systems utilizes a spectrometer slit that transmits light to a detector, which has approximately one-fifth the illumination NA (NA). COLL ~NA ILL / 5) of the collection NA. Assuming the illumination NA is approximately 0.07, then the collection NA for this measurement scenario is approximately 0.014. For a measurement cell size S of 50 micrometers and a B of 1 NC The value, equation (1) illustrates that the size requirement of the measuring box can be met when the illumination wavelength is less than 700 nm.

[0017] As described above, the ultra-low collection NA measurement scenario used in conventional SE measurement systems employs a spectrometer slit that transmits light to a detector, which has a collection NA of approximately one-twentieth of the illumination NA. COLL ~NA ILL The collection NA is approximately 0.0035 for a measurement scenario of / 20). Assuming the illumination NA is approximately 0.07, then the collection NA for this measurement scenario is approximately 0.0035. This is for a measurement cell size S of 50 micrometers and a B of 1. NC The value, equation (1) illustrates that the size requirement of the measuring box can be met when the illumination wavelength is less than 175 nanometers.

[0018] Equation (2) graphically illustrates the design criteria for collecting numerical aperture (NA) data to meet the spectral resolution requirements of the SE metrology system when probing deep structures, where NA... COLL For the desired collection of NA, λ is the wavelength of the illumination light under consideration, D is the maximum depth of the structure under consideration, and n is the typical refractive index of the material being measured. Typically, for typical semiconductor materials, such as oxides and nitrides, the value of n is in the range of 1.4 to 2.0, the value of D is in the range of 10 micrometers to 30 micrometers, and the range of wavelengths under consideration is wide, for example, from 400 nanometers to 2,500 nanometers, or even larger.

[0019] (2)

[0020] Assuming a collection NA of 0.014, a measurement depth D of 20 μm, and a refractive index of 1.46 (i.e., the refractive index of silica) for a low collection NA measurement scenario, equation (2) graphically illustrates that the spectral resolution requirement is met when the illumination wavelength is greater than 4.9 μm. At such large wavelengths, the signal-to-noise ratio at the detector is extremely poor, making it practically impossible to meet the spectral resolution requirement. Furthermore, in low collection NA measurement scenarios, it is impossible to meet both the spectral resolution requirement and the measurement cell size requirement at any illumination wavelength.

[0021] Assuming a collection NA of 0.0035, a measurement depth D of 20 micrometers, and a refractive index of 1.46 for an ultra-low collection NA measurement scenario, equation (2) graphically illustrates that the spectral resolution requirement can only be met when the illumination wavelength is greater than 1.2 micrometers. Although this is reasonable from a signal-to-noise ratio perspective, it is impossible to meet both the spectral resolution requirement and the measurement box size requirement at any illumination wavelength in an ultra-low collection NA measurement scenario.

[0022] Generally, current spectral elliptic polarization measurement systems do not offer available solutions for illumination NA and collection NA that can meet the measurement cell size and signal resolution requirements for deep structures at current and future semiconductor manufacturing nodes.

[0023] In summary, the continuous reduction in feature size, the increasing depth and number of layers in structural features, and the increasing use of opaque material layers place challenging demands on optical metrology systems. These systems must meet the high precision and accuracy requirements of increasingly complex targets with high throughput while remaining cost-effective. In this context, the collection of analog (NA) data and its resolution have become critical performance constraints in the design of optical metrology systems suitable for high aspect ratio structures with a relatively large number of layers (e.g., over 300 layers). Therefore, improvements to metrology systems and methods are desired to overcome these limitations. Summary of the Invention

[0024] This paper presents a method and system for performing spectral ellipsometric measurements of semiconductor structures using a collected NA resolved at a detector. The collected NA defines a small measurement cell size. Resolving the collected NA at the detector significantly improves spectral resolution, specifically at wavelengths less than 700 nm. In some examples, the collected NA is resolved into at least 10 subdivisions at the detector. Therefore, the detected NA is a fraction of the collected NA. This achieves ultra-high spectral resolution in wavelength ranges from 400 nm to 2,000 nm, 400 nm to 2,500 nm, or greater, which allows for a significant improvement in measurement sensitivity.

[0025] Spectral elliptometry measurements of semiconductor structures using a detector-resolved NA collection enable critical size measurements, shape and profile measurements, and film measurements of deep structures fabricated according to current semiconductor fabrication nodes, as well as those considered for fabrication at future semiconductor fabrication nodes. By way of non-limiting examples, spectral elliptometry measurements of semiconductor structures using a detector-resolved NA collection enables the measurement of features such as 3D NAND memory structures with more than 300 layers (e.g., 300 to 1,000 layers), 3D DRAM memory structures deeper than 10 micrometers, CMOS-based image sensors, power devices, semiconductor-bonded through-silicon via (TSV) structures, and microelectromechanical systems (MEMS) with deep trenches and holes (e.g., 20 mm or deeper, 100 mm or deeper).

[0026] In one aspect, the measurement system based on spectral ellipsometric measurement employs angle-resolved detection to achieve a small measurement cell size and high spectral signal resolution, maintaining measurement sensitivity across wavelength ranges from 400 nm to 2,000 nm, 400 nm to 2,500 nm, or greater. In some embodiments, the collected NA is approximately half the illumination NA (NA... COLL ~NA ILL / 2), and the detection NA is approximately one-twentieth to one-fiftieth of the illumination NA (NA DET ~NA ILL / 20 to NA DET ~NA ILL / 50). An angle-resolved detection solution space for illumination NA, collection NA, and detection NA in a spectral ellipsometric measurement system is provided, which enables the desired measurement cell size and signal resolution requirements for deep structures at current and future semiconductor manufacturing nodes.

[0027] Angle-resolved detection of the collection NA provides a relatively large dataset associated with each measurement. In some examples, the total collection NA is subdivided into 50 to 100 subranges at the detector; that is, the detected intensities are resolved into 50 to 100 distinct values, each associated with a different subrange. This relatively large dataset is sensitive to variations in minimally eigenvalued geometry deeply embedded within the measured structure. Without angle-resolved detection of the collection NA, the total collection NA is not resolved; that is, the detected intensities associated with the entire collection NA are aggregated into a single value. This relatively small dataset is either insensitive to variations in the many different geometric features deeply embedded within the measured structure or computationally unstable due to a lack of sensitivity to the parameters of interest.

[0028] In some embodiments, the angle-resolved spectral ellipsometer employing the collected NA includes an incoherent illumination source, such as a laser-continuous plasma source. In some embodiments, the angle-resolved spectral ellipsometer employing the collected NA includes a coherent illumination source, such as a supercontinuum-based source. In some embodiments, the coherent high-brightness illumination source achieves high spectral intensity and thus has a good signal-to-noise ratio across the wavelength range of 400 nm to 2,000 nm, 400 nm to 2,500 nm, or greater, with a shorter integration time compared to the incoherent illumination source.

[0029] In some embodiments, the angle-resolved spectral ellipsometer employing the collected NA includes both coherent and incoherent illumination sources. In some embodiments, illumination is provided by a supercontinuum laser source and a laser-driven plasma source. The supercontinuum laser source provides illumination at wavelengths greater than 400 nm, and in some embodiments, up to 5 μm or greater. The laser-driven plasma (LSP) source (also known as a laser-driven plasma source) generates photons across the entire wavelength range from 170 nm to 2500 nm and above.

[0030] In some embodiments, the measurement system employing angle-resolved detection based on spectral elliptic polarization measurement includes a spatially and temporally coherent high-brightness supercontinuum laser illumination source and a spatially and temporally coherent high-brightness mid-infrared laser illumination source, such as a frequency comb-based source. The mid-IR laser illumination source produces illumination in the wavelength range from 5 micrometers to 15 micrometers. The combination of the supercontinuum laser source and the mid-IR laser illumination source effectively extends the spectral range of the SE-based measurement system from 400 nanometers to 5 to 15 micrometers.

[0031] In another aspect, a measurement system employing angle-resolved detection based on spectral ellipsometric measurement is configured to scan the illumination beam over the surface of the sample being measured at a frequency at least ten times the detection frequency of the measurement system. Scanning the illumination beam over the sample surface at a frequency at least twice the detection frequency effectively expands the measurement area on the wafer beyond the nominal incident illumination beam size and effectively averages the speckle effect caused by the coherent illumination source (e.g., a laser-based illumination source).

[0032] In another embodiment, a measurement system employing angle-resolved detection based on spectral ellipsometric measurement resolves the collected light into discrete wavelengths along one direction and into discrete collection sub-ranges defined by the detector NA along another direction on its working surface. The detector resolves the collected light into discrete wavelengths along one direction and into discrete collection sub-ranges along another direction. The angular range of each collection sub-range defines the detector NA; that is, the collection NA is the angular range corresponding to the resolution by the detector. In some embodiments, the detector resolves the collection NA into at least ten collection sub-ranges. In some embodiments, the detector resolves the collection NA into at least 50 collection sub-ranges. In some embodiments, the detector resolves the collection NA into at least 100 collection sub-ranges.

[0033] The foregoing is a summary of the invention and therefore necessarily contains simplifications, summaries, and omissions of details; thus, those skilled in the art will understand that the summary is illustrative only and not in any way limiting. Other aspects, inventive features, and advantages of the apparatus and / or processes described herein will become apparent from the non-limiting embodiments set forth herein. Attached Figure Description

[0034] Figure 1 An exemplary metrology system 100 is depicted for performing spectral measurements of semiconductor structures using angle-resolved detection as described herein.

[0035] Figure 2 Another exemplary metrology system 100 is depicted for performing spectral measurements of semiconductor structures using angle-resolved detection as described herein.

[0036] Figure 3 This is a simplified diagram illustrating the working surface of the detector in a metrology system used to perform spectral measurements of semiconductor structures using angle-resolved detection as described herein.

[0037] Figure 4 It is a graph illustrating the spectral brightness of incoherent and coherent lighting sources.

[0038] Figure 5 An exemplary high aspect ratio semiconductor structure 160 is depicted, which is subjected to low light penetration into the measured structure.

[0039] Figure 6 Example 180 depicting a combined lighting source.

[0040] Figure 7A Another embodiment 200 of a combined lighting source is depicted.

[0041] Figure 7B Another embodiment 220 of the combined lighting source is depicted.

[0042] Figure 7C Another embodiment 240 of the combined lighting source is depicted.

[0043] Figure 8 The graphs depict specific detection rates of various detector techniques operating at specified temperatures.

[0044] Figure 9 A diagram depicting a multi-band infrared detector 270.

[0045] Figure 10 The diagram illustrates typical photosensitivity curves for four types of indium gallium arsenide (InGaAs) sensors.

[0046] Figure 11 Illustrated method 400 for performing spectral measurements of one or more structures using angle-resolved detection as described herein. Detailed Implementation

[0047] The invention will now be illustrated in detail with reference to prior art examples and some embodiments thereof, with the accompanying drawings illustrating examples of the invention.

[0048] This document presents a method and system for performing spectral ellipsometric measurements of semiconductor structures using a collected NA resolved at a detector. The collected NA achieves a small measurement cell size, while the resolution of the collected NA at the detector significantly improves the spectral resolution, specifically at wavelengths less than 700 nm. In some embodiments, the collected NA is specified to achieve a measurement cell size of 50 μm × 70 μm or less. This enables measurements of scribing metrological targets as well as practical device measurements of deep structures, i.e., intra-cell measurements. Moreover, resolving the collected NA at the detector into at least 10 subdivided collected NAs achieves ultra-high spectral resolution in wavelength ranges from 400 nm to 2,000 nm, 400 nm to 2,500 nm, or greater. In this way, the detected NA is a high fraction of the collected NA, which allows for a significant increase in measurement sensitivity.

[0049] Spectral elliptometry measurements of semiconductor structures using a detector-resolved NA collection enable critical size measurements, shape and profile measurements, and film measurements of deep structures fabricated according to current semiconductor fabrication nodes, as well as those considered for fabrication at future semiconductor fabrication nodes. By way of non-limiting examples, spectral elliptometry measurements of semiconductor structures using a detector-resolved NA collection enables the measurement of features such as 3D NAND memory structures with more than 300 layers (e.g., 300 to 1,000 layers), 3D DRAM memory structures deeper than 10 micrometers, CMOS-based image sensors, power devices, semiconductor-bonded through-silicon via (TSV) structures, and microelectromechanical systems (MEMS) with deep trenches and holes (e.g., 20 mm or deeper, 100 mm or deeper).

[0050] In one aspect, a measurement system based on spectral ellipsometric measurement employs angle-resolved detection to achieve a small measurement cell size (e.g., less than 70 micrometers) and high spectral signal resolution, maintaining measurement sensitivity across wavelength ranges from 400 nm to 2,000 nm, 400 nm to 2,500 nm, or greater. Angle-resolved detection of the collected NA achieves moderate to moderate collected NA and ultra-low NA resolution at the detector. This significantly enhances measurement capabilities, such as accuracy, precision, and stability, while maintaining a small measurement cell size. In some embodiments, the collected NA is approximately half the illumination NA (NA... COLL ~NA ILL / 2), and the detection NA is approximately one-twentieth to one-fiftieth of the illumination NA (NA DET ~NA ILL / 20 to NA DET ~NA ILL / 50). Angular-resolved detection of the collection NA enables a solution space for the illumination NA, collection NA, and detection NA in a spectral elliptometric measurement system, allowing for desired measurement cell size and signal resolution requirements for deep structures at current and future semiconductor manufacturing nodes. Angular-resolved detection of the collection NA provides a relatively large dataset of dimensions associated with each measurement. In some examples, the total collection NA is subdivided into 50 to 100 subranges at the detector; that is, the detected intensities are resolved into 50 to 100 distinct values, each associated with a different subrange. This relatively large dataset is sensitive to variations in minimally eigenvalued geometry deeply embedded within the measured structure. Without angular-resolved detection of the collection NA, the total collection NA is not resolved; that is, the detected intensities associated with the entire collection NA are aggregated into a single value. This relatively small dataset is either insensitive to variations in many different geometries deeply embedded within the measured structure or computationally unstable due to a lack of sensitivity to the parameters of interest.

[0051] Figure 1 and 2 Exemplary metrology systems 100 and 300 are depicted for performing spectroscopic measurements (e.g., film thickness, critical dimensions, stacking, etc.) of semiconductor structures. In some examples, one or more structures include at least one high aspect ratio (HAR) structure. In some of these examples, one or more structures include at least 200 different layers. Figure 1 and 2 As depicted, metrology systems 100 and 300 are configured as tilt-incident spectral ellipsometers. However, in general, metrology systems 100 and 300 may also include additional spectral ellipsometers, spectral reflectometers, scatterometers, or any combination thereof.

[0052] Figure 1The metrology system 100 depicted includes an incoherent illumination source 110 that generates an illumination beam 101 incident on a wafer 120. The illumination source 110 includes one or more illumination sources emitting illumination light with wavelengths ranging from 400 nm to 2,500 nm. In some embodiments, the illumination source 110 is a single illumination source, such as a laser-driven plasma (LSP) source (also known as a laser-driven plasma source) or an arc lamp source, emitting illumination light with ultraviolet, visible, and infrared spectra, the illumination light including ultraviolet wavelengths down to 400 nm and infrared wavelengths greater than 2 μm, for example, illumination wavelengths ranging from 400 nm to 2,500 nm. In some other embodiments, the illumination source 110 is a combined illumination source emitting illumination light with ultraviolet, visible, and infrared spectra, the illumination light including ultraviolet wavelengths down to 400 nm and infrared wavelengths greater than 2 μm, for example, illumination wavelengths ranging from 400 nm to 2,500 nm. In some other embodiments, the illumination source 110 is a combined illumination source that emits illumination light with wavelengths ranging from 400 nanometers to 7,000 nanometers.

[0053] In some embodiments, the illumination source 110 comprises a supercontinuum laser source and a laser-driven plasma source. The supercontinuum laser source provides illumination at wavelengths greater than 400 nanometers, and in some embodiments, up to 5 micrometers or greater. The laser-driven plasma (LSP) source (also known as a laser-driven plasma source) generates photons across the entire wavelength range from 170 nanometers to 2,500 nanometers and above. The pump laser of the LSP source can be continuous-wave or pulsed. In some embodiments, the combined illumination source 110 comprises a supercontinuum laser source and an arc lamp, such as a xenon arc lamp. However, a laser-driven plasma source generates significantly more photons across the entire wavelength range from 170 nanometers to 2,500 nanometers than a xenon lamp, and is therefore preferred.

[0054] The combined lighting source 110 comprises a combination of multiple broadband or discrete wavelength light sources. The light produced by the combined lighting source 110 comprises a continuous spectrum or a portion of a continuous spectrum from ultraviolet to infrared light (e.g., vacuum ultraviolet to long infrared). Generally, the combined lighting source 110 may include a supercontinuum laser source, an infrared helium-neon laser source, a silicon carbide spherical light source, a tungsten halide light source, one or more infrared LEDs, one or more infrared lasers, or any other suitable infrared light source that produces wavelengths greater than 2 micrometers, as well as arc lamps (e.g., xenon arc lamps), deuterium lamps, LSP light sources, or any other suitable light source that produces wavelengths in the range of 400 nm to 2,000 nm, 400 nm to 2,500 nm, or greater.

[0055] Generally, the combined illumination source 110 comprises multiple illumination sources optically coupled in any suitable manner. In some embodiments, light emitted by a supercontinuum laser source is directly coupled via plasma generated by an ultraviolet / visible light source.

[0056] Figure 6 Embodiment 180 of the combined lighting source 110 is depicted. (As shown) Figure 6 As depicted, an LSP-pumped laser source 181 generates pump light 182 focused by focusing optics 183 to maintain the plasma 184 contained within a bulb 185. The plasma 184 generates broadband spectral light in the wavelength range from ultraviolet to short infrared. The bulb 185 includes an exit port 186. The LSP output light 187 is a portion of the light from the plasma 184, which passes through the exit port 186 and is directed towards the plasma as shown in the reference optics. Figure 1 The described illumination optics subsystem is guided. Additionally, a supercontinuum laser source 191 generates infrared light 192, which is focused by focusing optics 193 onto or near a focal point 194 on the plasma 184. The supercontinuum output light 197 is a portion of the light from the focal point 194, which passes through the exit port 186 and is directed as shown in the reference... Figure 1 The described illumination subsystem is guided. In one example, the LSP output light 187 and the supercontinuum output light 197 are co-located. In this way, infrared light 197 from the supercontinuum source 191 is effectively combined with ultraviolet / visible light 187 from the LSP laser source 181. In one example, the LSP output light 187 and the supercontinuum output light 197 have the same or similar illumination numerical aperture. In another example, the LSP output light 187 and the supercontinuum output light 197 have different illumination numerical apertures. In some examples, the bulb 185 is made of calcium fluoride or magnesium fluoride to transmit wavelengths above 2.5 micrometers generated by the supercontinuum laser source 191. In some other examples, the bulb 185 includes one or more exit ports 186 made of calcium fluoride or magnesium fluoride to transmit wavelengths above 2.5 micrometers generated by the supercontinuum laser source 191. Conventional bulbs made of fused silica do not transmit significant light above 2.5 micrometers and are therefore unsuitable for combining light generated by the supercontinuum laser source 191 in the manner described herein. In some embodiments, the LSP-pumped laser source 181 is a continuous-wave laser. In some other embodiments, the LSP-pumped laser source 181 is a pulsed laser.

[0057] Figure 7A An embodiment 200 of the combined lighting source 110 is depicted. (As shown...) Figure 7AAs depicted, the voltage supplied across the cathode 208 and anode 209 generates plasma 204 contained in the bulb 205. Additionally, an LSP-pumped laser source 201 generates pump light 202 focused by focusing optics 203 to maintain the plasma 204 contained in the bulb 205. The plasma 204 generates broadband spectral light in the wavelength range from ultraviolet to short infrared. The ultraviolet / visible / short infrared light 207 generated by the plasma 204 is provided as shown in the reference. Figure 1 The described illumination optics subsystem. Additionally, a supercontinuum laser source 211 generates infrared light 212. The infrared light 212 is focused by a focusing lens 213, forming a focal point 214 at or near the plasma 204. Infrared light 217 from the focal point 214 is provided as referenced. Figure 1 The described lighting optics subsystem. In one example, UV / visible / short infrared light 207 and infrared light 217 are co-located and effectively combined. In some examples, the bulb 205 is made of calcium fluoride or magnesium fluoride to transmit wavelengths above 2.5 micrometers generated by the supercontinuum laser source 211. In some other examples, the bulb 205 includes one or more emission ports 206 made of calcium fluoride or magnesium fluoride to transmit wavelengths above 2.5 micrometers generated by the supercontinuum laser source 211. Conventional bulbs made of fused silica do not transmit significant light above 2.5 micrometers and are therefore unsuitable for combining light generated by the supercontinuum laser illumination source 211 in the manner described herein.

[0058] Figure 7B Embodiment 220 of the combined lighting source 110 is depicted. (As shown) Figure 7B As depicted, the voltage supplied across the cathode 228 and anode 229 generates plasma 224 within the bulb 225. Additionally, an LSP-pumped laser source 221 generates pump light 222 focused by focusing optics 223 to maintain the plasma 224 within the bulb 225. The plasma 224 generates broadband spectral light in the wavelength range from ultraviolet to short infrared. The ultraviolet / visible / short infrared light 227 generated by the plasma 224 exits the bulb 225 through the exit port 226 and is provided to the reference... Figure 1 The described illumination optics subsystem. Additionally, a supercontinuum laser source 231 generates infrared light 232. The infrared light 232 is focused by a focusing lens 233. The infrared light 237 from the supercontinuum laser source 231 is provided as referenced. Figure 1 The described lighting optics subsystem.

[0059] like Figure 7BAs depicted, UV / visible / short infrared light 227 and infrared light 237 are combined by beam combiner 234. Thus, beam combiner 234 combines light generated by ultraviolet light source 221 (e.g., LSP source 221) with light generated by infrared light source 231 (e.g., supercontinuum laser source 231). In one example, beam combiner 234 has a split wavelength of, for example, 900 nm or close to 900 nm. The beam combiner minimizes the loss of light generated by the LSP source (LSP loss less than 10%) and minimizes depolarization effects (e.g., less than 0.1%) across all illumination wavelengths.

[0060] Figure 7C Embodiment 240 of the combined lighting source 110 is depicted. (As shown) Figure 7C As depicted, the voltage supplied across the cathode 248 and anode 249 generates plasma 244 contained within the bulb 245. Additionally, an LSP-pumped laser source 241 generates pump light 242 focused by focusing optics 243 to maintain the plasma 244 contained within the bulb 245. The plasma 244 generates broadband spectral light in the wavelength range from ultraviolet to short infrared. The ultraviolet / visible / short infrared light 247 generated by the plasma 244 exits the bulb 245 through the exit port 246 and is provided to the reference... Figure 1 The described illumination optics subsystem. Additionally, a supercontinuum laser source 251 generates infrared light 252. The infrared light 252 is focused by a focusing lens 253. The infrared light 257 from the supercontinuum laser source 251 is provided as referenced. Figure 1 The described lighting optics subsystem.

[0061] like Figure 7C As depicted, the combined illumination source 110 selectively provides ultraviolet and infrared illumination light to the chip 120. In these examples, the measurements are time-multiplexed. Mirror 254 is a movable mirror. In one example, the movable mirror 254 is mounted to a galvanometer used to selectively guide the ultraviolet / visible light 247 and infrared light 257 to the chip 120 based on whether the movable mirror 254 is located within or outside the optical path of the ultraviolet / visible light 247. In another example, a movable total internal reflection prism is used to selectively guide the ultraviolet / visible light 247 and infrared light 257 to the chip 120. In this way, spectral measurements including the ultraviolet / visible light spectrum are performed at different times than spectral measurements including the infrared light spectrum.

[0062] In some embodiments, the measurement system employing angle-resolved detection based on spectral ellipsometric measurements utilizes an illumination source comprising one or more spatially and temporally coherent high-brightness illumination sources and excluding incoherent illumination sources. The coherent high-brightness illumination sources achieve high spectral intensity and thus exhibit good signal-to-noise ratios across wavelength ranges of 400 nm to 2,000 nm, 400 nm to 2,500 nm, or greater, with shorter integration times compared to incoherent illumination sources.

[0063] Figure 2 The metering system 300 depicted includes a coherent illumination source 310 that generates an illumination beam 301 incident on the wafer 120. Figure 3 The similarly numbered elements referenced in the document are similar to the reference. Figure 1 The elements described. In a preferred embodiment, the illumination source 310 comprises a supercontinuum laser source. The supercontinuum laser source provides spatially and temporally coherent high-brightness illumination at wavelengths from 400 nm to 2,000 nm, 400 nm to 2,500 nm or larger (e.g., up to 5 micrometers or larger).

[0064] Figure 4 These are graphs illustrating the brightness of supercontinuum laser sources and typical incoherent plasma lamp sources used in semiconductor metrology applications as a function of wavelength. Curve 141 illustrates the spectral brightness of a supercontinuum laser source in the spectral range of 390 to 890 nanometers. Similarly, curve 142 illustrates the spectral brightness of an incoherent plasma lamp source in the same spectral range. Figure 4 As described in the paper, the supercontinuum light source has 30 to 100 times higher spectral brightness compared to typical incoherent plasma lamp light sources used in semiconductor metrology applications (including 3D NAND metrology).

[0065] The high spectral brightness across wavelengths from 400 nm to 2,000 nm, 400 nm to 2,500 nm, or even greater enables high spectral measurement sensitivity and high throughput for deep structure measurements. Even with ultra-low NA detection, the high spectral brightness provides sufficient signal strength and a good signal-to-noise ratio.

[0066] In some embodiments, the measurement system employing angle-resolved detection based on spectral elliptic polarization measurement includes a spatially and temporally coherent high-brightness supercontinuum laser illumination source and a spatially and temporally coherent high-brightness mid-infrared laser illumination source, such as a frequency comb-based source. The mid-IR laser illumination source produces illumination in the wavelength range from 5 micrometers to 15 micrometers. The combination of the supercontinuum laser source and the mid-IR laser illumination source effectively extends the spectral range of the SE-based measurement system from 400 nanometers to 5 to 15 micrometers.

[0067] like Figure 1As depicted, the metrology system 100 includes an illumination subsystem configured to guide illumination light 101 to one or more structures formed on the wafer 120. The illumination subsystem may include optical filters, polarizing components, field-of-view diaphragms, pupil diaphragms, etc., of any type and arrangement known in spectrometric techniques, including spectral ellipsometric measurements. Figure 1 As depicted, the illumination subsystem includes a light source 110, beam-shaping optics 111, 112, 115, and 121, a polarizing assembly 113, and a pupil stop 114. (As...) Figure 1 As depicted, when the beam from illumination source 110 propagates to wafer 120, illumination beam 101 is reflected from beam-shaping optics 111, 112, 115, and 121 and passes through polarizing assembly 113 and pupil stop 114. Beam 101 illuminates a portion of wafer 120 above measurement spot 116.

[0068] exist Figure 1 In the embodiment depicted, the pupil stop 114 controls the numerical aperture (NA) of the illumination at the chip. ILL The illumination subsystem may include any commercially available aperture stop suitable for use. In one aspect, the illumination subsystem is configured to direct illumination light 101 to wafer 120 with an illumination numerical aperture (NA) of less than 0.15. In some examples, the illumination numerical aperture (NA) is less than 0.10, for example, about 0.07 or less. In one aspect, the illumination NA provides an illumination spot fitted within a scribing at wafer 120. This enables measurement of scribing metrological targets. In some embodiments, illumination light 101 is focused on a 50 μm × 50 μm scribing target area. In some embodiments, illumination light 101 is focused on a 50 μm × 100 μm scribing target area. In some embodiments, illumination light 101 is focused on a 50 μm × 150 μm scribing target area. In some embodiments, illumination light 101 is incident on wafer 120 at a nominal incident angle α of 65 degrees or close to 65 degrees with respect to the normal.

[0069] Additionally, the illumination subsystem may include filters, masks, apodizers, etc. For example, the illumination subsystem may include an illumination field-of-view (FOV) stop (not shown) and one or more optical filters (not shown). The illumination FOV stop controls the field of view (FOV) of the illumination subsystem and may include any commercially available FOV stop suitable for use. Optical filters are used to control the light level, spectral output, or both from the illumination subsystem. In some examples, one or more multi-band filters are used as optical filters. Figure 1 As depicted, the beam-shaping optics 111, 112, 115 and 121 include one or more optical elements with reflective focusing capabilities.

[0070] In some examples, the beam size of a certain amount of illumination light 120 projected onto the surface of wafer 101 is smaller than the size of the measurement target measured on the surface of the sample. Exemplary beamforming techniques are described in detail in U.S. Patent Application Publication No. 2013 / 0114085 by Wang et al., the contents of which are incorporated herein by reference in their entirety.

[0071] In some examples, noise and polarization optimization are performed to improve the performance of illumination source 110. In some examples, depolarization is achieved using multimode fiber, Hanle depolarizer, or integrating sphere. In some examples, illumination source light spread is optimized using light guides, optical fibers, and other optical elements (e.g., lenses, mirrors, apodizers, etc.).

[0072] The polarizing assembly 113 produces the desired polarization state of the emitted illumination subsystem. In some embodiments, the polarizing assembly includes a polarizer, a compensator, or both, and may include any commercially available polarizing assembly suitable for use. The polarizer, compensator, or both may be fixed, rotatable to different fixed positions, or continuously rotatable. Although Figure 1 The depicted illumination subsystem includes one polarizing component, but the illumination subsystem may include more than one polarizing component. In some embodiments, the polarizer of polarizing component 113 is a magnesium fluoride Rochon polarizer. In some embodiments, the compensator of polarizing component 113 includes a quartz wave plate, a magnesium fluoride wave plate, a calcium fluoride K-prism, a calcium fluoride double Fresnel rhombus, or any combination thereof. In some embodiments, the compensator of polarizing component 113 includes one or more wave plates. In some of these embodiments, a first wave plate includes the desired blocking in a first wavelength range, and a second wave plate includes the desired blocking in a second wavelength range, and so on.

[0073] like Figure 2 As depicted, the metrology system 300 includes an illumination subsystem configured to guide illumination light 301 to one or more structures formed on the wafer 120. The illumination subsystem may include optical filters, polarizing components, field-of-view diaphragms, pupil diaphragms, etc., of any type and arrangement known in spectrometer techniques, and includes a reference... Figure 1 Any element described. For example... Figure 2 As depicted, the illumination subsystem includes a coherent light source 310 and optical elements 311 and 312 for guiding an illumination beam 301 from the illumination source 310 onto a measurement spot 116.

[0074] exist Figure 2 In the embodiments depicted, the numerical aperture (NA) of the illumination at the wafer is... ILLThe illumination source 310 is defined by a coherent laser-based illumination source. In one aspect, the illumination source is configured to direct illumination light 101 to wafer 120 with an illumination numerical aperture (NA) of less than 0.15. In some examples, the illumination numerical aperture (NA) is less than 0.10, for example, about 0.07 or less. Although Figure 2 The illumination NA is described as being set by an illumination source, but generally, the pupil stop may also be included in the illumination beam path from the illumination source 310 to the chip 120, which defines the illumination NA at the chip.

[0075] In another aspect, a measurement system employing angle-resolved detection based on spectral ellipsometric measurement is configured to scan the illumination beam over the surface of the sample being measured at a frequency at least ten times the detection frequency of the measurement system. Scanning the illumination beam over the sample surface at a frequency at least twice the detection frequency effectively expands the measurement area on the wafer beyond the nominal incident illumination beam size and effectively averages the speckle effect caused by the coherent illumination source (e.g., a laser-based illumination source).

[0076] like Figure 2 As depicted, illumination optics 312 is located in the illumination optical path from illumination source 310 to wafer 120. Additionally, illumination optics 312 is mechanically coupled to actuator subsystem 313, which is configured to change the orientation of illumination optics 312 according to command signal 319 transmitted from computing system 130 to actuator subsystem 313. In some embodiments, actuator subsystem 313 is a flip / tilt stage, such as a galvanometer stage, capable of changing the orientation of illumination optics 312 at extremely high frequencies. In some embodiments, actuator subsystem reorients illumination optics 312 such that illumination beam 301 repeatedly follows the path of filling measurement spot 116 on wafer 120 at an extremely high repetition rate. In some examples, actuator subsystem reorients illumination optics 312 such that illumination beam 301 follows the path of filling measurement spot 116 on wafer 120 at a repetition rate at least ten times the detection frequency of the detector. In this way, each detection repetition effectively averages the incident illumination that is scanned over the entire measurement spot 116. In other words, at any given moment, the illumination beam fills only a small portion of the measurement spot 116, but by the time the detector completes a measurement, the illumination beam has already scanned the entire measurement spot 116 at least ten times.

[0077] The metrology system 100 also includes a collection optics subsystem configured to collect light generated by the interaction between one or more structures and the incident illumination beam 101, and to focus the collected light at or near a dispersive element of the spectrometer (e.g., a spectrometer slit). The collection optics subsystem may include any type and arrangement of optical filters, polarizing assemblies, field-of-view diaphragms, pupil diaphragms, etc., known in spectrometrology techniques. Generally, the collection optics subsystem includes a field-of-view diaphragm, a pupil mask, and one or more optical elements with reflective focusing capabilities.

[0078] like Figure 1 As depicted, the collected light beam 102 is collected from the measurement spot 116 by the collection subsystem. When the collected light beam 102 propagates from the wafer 120 to the dispersive element 127 of the spectrometer, the collected light 102 is reflected from the beam-shaping optics 129, 122 and 126, and passes through the compensator 123, analyzer 124, collection mask 125 and collection field-of-view aperture 103 of the collection optics subsystem.

[0079] like Figure 1 As depicted, the optical collection subsystem includes a polarizing component that analyzes the polarization state of the collected light. In some embodiments, the polarizing component includes an analyzer, a compensator, or both, and may include any commercially available polarizing component suitable for use. The analyzer, compensator, or both may be fixed, rotatable to different fixed positions, or continuously rotatable. Figure 1 The collection subsystem depicted includes a compensator 123 and an analyzer 124. Generally, the collection optics subsystem may contain any number of polarizing elements.

[0080] In some embodiments, compensator 123 comprises a quartz waveplate, a magnesium fluoride waveplate, a calcium fluoride K-prism, a calcium fluoride double Fresnel rhombus, or any combination thereof. In some embodiments, compensator 123 comprises one or more waveplates. In some of these embodiments, a first waveplate contains the desired blocking in a first wavelength range, and a second waveplate contains the desired blocking in a second wavelength range, and so on. In some embodiments, analyzer 124 is a magnesium fluoride Roshan analyzer.

[0081] like Figure 1As depicted, the collecting optics subsystem includes a collecting mask 125 disposed at or near the pupil of the collecting optics subsystem. The collecting mask 125 includes an aperture, i.e., an opening, configured to select and transmit collected light within a collecting angle range defined by the collecting numerical aperture (NA). The collecting angle range corresponds to some or all of the range of incident angles with respect to the nominal incident angle defined by the illumination NA. In some examples, the collecting mask 125 is configured to transmit collected light corresponding to the nominal incident angle with a collecting NA of at least 0.02 and no greater than 0.15. In this way, the collecting mask 125 controls the NA of the collecting subsystem.

[0082] The field-of-view aperture 103 controls the field of view of the collecting optics subsystem. In some other embodiments, a slit at or near the dispersive element 127 (e.g., a spectrometer slit) is used to define the field of view of the collecting optics subsystem.

[0083] exist Figure 1 In the embodiments depicted, the spectrometer subsystem includes a collection field-of-view aperture 103, a dispersive element 127, and a focusing optics 126. In some embodiments (not shown), the focusing optics 126 is a group of one or more optical devices with reflective focusing capability. The collection field-of-view aperture 103 receives light from the collection optics subsystem and transmits a portion of the collected light to the dispersive element 127. The dispersive element 127 is typically located at or near the pupil plane of the collection optics subsystem. Figure 1 In the embodiments depicted, light from the collection mask 125 is imaged from the collection mask 125 onto the pupil plane at or near the dispersive element 127.

[0084] Dispersive element 127 is typically a diffraction grating or a dispersive prism. Dispersive element 127 receives light from collection mask 125 corresponding to a collection angle range defined by collection NA, which in turn corresponds to an incident angle range with respect to a nominal incident angle. In some embodiments, dispersive element 127 is a planar diffraction grating. Dispersive element 127 disperses the collected light across the detector's working surface in two dimensions. Dispersive element 127 disperses the collected light across the detector's working surface in one direction according to wavelength, and disperses the collected light across the detector's working surface in another direction orthogonal to the first direction according to the incident angle. The range of incident angles dispersed across the detector is defined by collection NA.

[0085] In one aspect, the detector resolves the collected light into discrete wavelengths along one direction on the detector's working surface, and resolves the collected light into a discrete subrange of collection angles defined by the detector NA along another direction.

[0086] like Figure 1As depicted, the metrology system 100 includes at least one detector, such as detector 128, having a planar two-dimensional surface sensitive to incident light. Detector 128 is selected for signal-to-noise ratio performance and fast readout. Detector 128 detects a certain amount of collected light and generates an output signal 154 indicating the detected light. The collected light is dispersed onto detector 128 according to the wavelength dispersion direction of at least one detector and according to the collection angle within the collection angle range corresponding to the incident angle range along a second direction of at least one detector. In a preferred embodiment, the first direction is orthogonal to the second direction. Detector 128 resolves the collected light into discrete wavelengths along one direction and into discrete sub-ranges of collection angles along another direction. The angular range of each collection angle sub-range defines detector NA, i.e., the collection NA is the angular range corresponding to which detector resolves. In one example, detector NA (NA DET ) is the collection of NA (NA) COLL Divide by the number of sub-ranges resolved by the detector. For example, if the collection NA that disperses across the detector is 0.10, and the collection NA is resolved by the detector into ten distinct sub-ranges, then the detector NA associated with each sub-range is 0.01. In some embodiments, the detector resolves the collection NA into at least ten collection sub-ranges. In some embodiments, the detector resolves the collection NA into at least 50 collection sub-ranges. In some embodiments, the detector resolves the collection NA into at least 100 collection sub-ranges.

[0087] Figure 3 It is a diagrammatic explanation. Figure 1 and 2 A simplified diagram of the surface of detector 128 is shown. The pixels of detector 128 are arranged in a two-dimensional array, extending in both the horizontal and vertical directions relative to the drawing page. Detector 128 contains N columns. COLUMNS and the number of rows N ROWS In some embodiments, detector 128 comprises 1,000 to 5,000 columns and 100 to 200 rows or more. Figure 3 The diagram illustrates that, from the minimum resolvable wavelength λmin to the maximum resolvable wavelength λmax, the collected light is dispersed horizontally across detector 128. Additionally, the collected light is dispersed across the detector depending on the incident angle in the vertical direction. Complete collection NA (NA COLL It spans the detector surface in the vertical direction. Furthermore, detector 128 will resolve the collected NA into K individual NA subbands, i.e., NA... BAND1 NA BAND2 ..., NA BANDKIn this example, the NA associated with each NA subband (i.e., the detector NA) corresponds to the collected NA divided by K. The NA associated with each row of detector 128 (NA...) ROW The value is the collection NA divided by the number of rows of detector 128 spanned by the collection NA. However, the detector NA is the resolved NA associated with each NA sub-band. In some examples, each row corresponds to a separate NA sub-band. In these examples, the detector NA is associated with the NA. ROW The same applies. However, in other examples, multiple rows are contained within an NA subband, and the intensity values ​​of the rows contained within a particular NA subband are summed to obtain the intensity value associated with each subband at a resolved wavelength.

[0088] The measurement system 100 also includes a computing system 130, which is configured to receive a detected signal 154 and determine an estimate 155 of the value of the parameter of interest of the measured structure based on the detected signal.

[0089] Generally, the optical collection subsystem can direct light to more than one detector. In these embodiments, two or more detectors are each configured to simultaneously detect the collected light in different wavelength ranges.

[0090] In one example, one detector is a charge-coupled device (CCD) sensitive to ultraviolet and visible light (e.g., light with wavelengths between 190 nm and 860 nm), and the other detector is a photodetector array (PDA) sensitive to infrared light (e.g., light with wavelengths between 950 nm and 5000 nm). However, in general, other two-dimensional detector techniques (e.g., position-sensitive detectors (PSDs), infrared detectors, photovoltaic detectors, etc.) should be considered. Each detector converts the incident light into an electrical signal representing the spectral intensity of the incident light. In some embodiments, the detection subsystem is arranged such that the collected light simultaneously propagates to all detectors of the metrology system 100. By simultaneously collecting UV and IR spectra, measurement time is reduced, and all spectra are measured under the same calibration conditions. This allows for easier correction of wavelength errors because common calibration can be applied to all spectral datasets.

[0091] Generally, the dispersive element 127 can be configured to subdivide the incident light into different wavelength bands, propagate the different wavelength bands in different directions, and disperse the light of one of the wavelength bands onto one or more detectors in any suitable manner. In one example, the dispersive element 127 is configured as a transmission grating. In some other examples, the dispersive element 127 includes a beam-splitting element that subdivides the beam into different wavelength bands and a reflective or transmission grating structure that disperses one of the wavelength bands onto the detectors.

[0092] In some embodiments, the dispersive element 127 is a reflective grating configured to diffract a subgroup of wavelengths of incident light toward one detector to a + / -1 diffraction order and a different subgroup of wavelengths of incident light toward another detector to a zero diffraction order.

[0093] Measuring targets using infrared, visible, and ultraviolet light within a single system enables precise characterization of complex three-dimensional structures. Generally, when measuring structures with relatively large spacing, relatively long wavelengths penetrate deep into the structure and provide suppression of high diffraction orders. Relatively short wavelengths provide precise dimensional information about the structure, such as relatively small CD (diameter density) and roughness characteristics. In some examples, longer wavelengths enable the measurement of dimensional properties of targets with relatively rough surfaces or interfaces due to their lower sensitivity to roughness. Generally, measuring targets using infrared, visible, and ultraviolet light within a single system improves sensitivity to some measurement parameters and reduces correlations among parameters (e.g., parameters characterizing the top and bottom layers).

[0094] In some embodiments, the methods and systems for spectrometric measurements of semiconductor devices described herein are applied to the measurement of high aspect ratio (HAR), large lateral dimension structures, opaque films, or combinations thereof. These embodiments enable optical critical dimension (CD), film, and composition metrology of semiconductor devices with HAR structures (e.g., NAND, VNAND, TCAT, DRAM, etc.) and more generally, complex devices subject to low light transmittance into the structure being measured. HAR structures typically include a hard mask layer to facilitate the etching process of the HAR. As described herein, the term "HAR structure" refers to any structure characterized by an aspect ratio greater than 2:1 or 10:1 and potentially up to 100:1 or higher.

[0095] Figure 5 A vertically integrated memory structure 160 is depicted, comprising a tungsten layer 161 sandwiched between oxide layers 162. For example... Figure 5 As depicted, the etching process leaves horizontal recesses in each tungsten layer 161 relative to the oxide layers 162 above and below each tungsten layer 161. The tungsten recess at or near the top of structure 160 is referred to as the top recess. The tungsten recess at or near the middle of structure 160 is referred to as the mid recess. The tungsten recess at or near the bottom of structure 160 is referred to as the bottom recess. The opening in the oxide layer 162 at or near the bottom of structure 160 is referred to as the bottom critical dimension (BCD).

[0096] In some embodiments, the spectroscopic measurement system includes a combined illumination source comprising a supercontinuum laser illumination source and a mid-IR laser illumination source. The combined illumination source generates illumination light with wavelengths as low as 400 nanometers. In some examples, the combined illumination source generates illumination light with wavelengths up to and including 4.2 micrometers. In some examples, the combined illumination source generates illumination light with wavelengths up to and including 5 micrometers. In some examples, the combined illumination source generates illumination light with wavelengths exceeding 5 micrometers. Furthermore, the spectroscopic measurement system includes one or more measurement channels spanning the illumination wavelength range used to perform semiconductor structure measurements. The one or more measurement channels can operate in parallel (i.e., simultaneously measuring samples across the entire wavelength range) or sequentially (i.e., sequentially measuring samples across the entire wavelength range).

[0097] Figure 8 Graph 260 illustrates the specific detection rates of various detector techniques operating at specified temperatures. (e.g.) Figure 8 The illustration shows that photovoltaic and photoconductivity detector technologies are suitable for detecting radiation at infrared wavelengths exceeding 1 micrometer and up to 5 micrometers. In some examples, the metrology system 100 includes detectors such as lead sulfide (PbS), lead selenide (PbSe), indium antimonide (InSb), indium arsenide (InAs), mercury cadmium telluride (HgCdTe), indium gallium arsenide (InGaAs), x-InGaAs, thermoelectric and radiation thermal detectors.

[0098] Thermoelectric and radiometric thermal detectors are not quantum detectors. Therefore, these detectors can accept high light levels without saturation, and thus reduce noise sensitivity.

[0099] In some embodiments, the detector subsystem is shot noise limited, rather than dark noise limited. In these examples, preferably, multiple measurements are performed at high light levels to reduce measurement system noise.

[0100] In some embodiments, time-dependent measurements (e.g., pulsed light sources, choppers, etc.) are performed in conjunction with lock-in amplifiers or other phase-locked loops to improve the measurement signal-to-noise ratio.

[0101] In some embodiments, one or more of the detectors are cooled to temperatures of -20°C, 210°K, 77°K, or other low temperatures to reduce measurement noise. Generally, any suitable cooling element can be used to maintain the detector temperature at a constant temperature during operation. Consider, by way of non-limiting examples, any of the following may fall within the scope of this patent document: a multi-stage Peltier cooler, a rotary disc cooler, a Stirling circulating cooler, an N2 cooler, a He cooler, etc.

[0102] In some embodiments, a wide range of wavelengths is detected by a detector comprising multiple photosensitive regions with different sensitivity characteristics. The collected light is linearly dispersed across the surface of the detector according to the wavelength in one direction and the angle of incidence in another direction. Each different photosensitive region is arranged on the detector to sense a different range of incident wavelengths. In this way, a wide range of wavelengths is detected by a single detector with a high signal-to-noise ratio. These features, individually or in combination, enable high-throughput measurements of high aspect ratio structures (e.g., structures with a depth of 1 micrometer or greater) with high throughput, precision, and accuracy.

[0103] In some embodiments, the detector subsystem includes multi-band infrared detectors with different sensitivity bands combined at different locations on a single detector package. Depending on the incident position, the detectors are configured to provide continuous data spectra with different sensitivities.

[0104] Figure 10 The diagram illustrates a typical photosensitivity curve for an indium gallium arsenide (InGaAs) sensor. For example... Figure 10 As described, none of the available InGaAs sensors can provide sufficient photosensitivity across the wavelength band from 1 micrometer to 2.5 micrometers. Therefore, individually, available sensors can only sense over narrow wavelength bands.

[0105] In some embodiments, multiple sensor chips, each sensitive in different wavebands, are combined into a single detector package. This multi-band detector is then implemented in the metrology system described herein.

[0106] Figure 9 Four sensor chips 270A to 270D, originating from four different wavelength bands, are depicted to constitute a multi-band infrared photodetector 180. The four sensor chips comprise different material compositions, each exhibiting different photosensitivity characteristics. For example... Figure 10 As depicted, sensor chip 270A exhibits high sensitivity in band A, sensor chip 270B exhibits high sensitivity in band B, sensor chip 270C exhibits high sensitivity in band C, and sensor chip 270D exhibits high sensitivity in band D. The metrology system incorporating detector 270 is configured to disperse wavelengths within band A to sensor chip 270A, wavelengths within band B to sensor chip 270B, wavelengths within band C to sensor chip 270C, and wavelengths within band D to sensor chip 270D. In this way, high photosensitivity (i.e., high SNR) is achieved over the combined bands A through D, which include wavelengths from a single detector. Therefore, by limiting the use of a particular sensor to a narrow band with high measurement sensitivity and low measurement noise, measurement noise is reduced throughout the measurement range.

[0107] In some examples, multi-band detectors include InGaAs sensors with sensitivity to different spectral regions, which are assembled in a single sensor package to produce a single continuous spectrum covering wavelengths from 750 nm to 3,000 nm or longer.

[0108] Generally, any number of individual sensors can be assembled along the wavelength dispersion direction of a multi-band detector, so that the continuous spectrum can be derived from the detector. However, typically, two to four individual sensors are used in a multi-band detector (e.g., detector 270).

[0109] In one embodiment, three individual sensors were employed, each having a first segment spanning between 800 nm and 1600 nm, a second segment spanning between 1600 nm and 2200 nm, and a third segment spanning between 2200 nm and 2600 nm.

[0110] Although the use of InGaAs-based infrared detectors is described in detail in this paper, in general, any suitable material exhibiting a narrow sensitivity range and a sharp sensitivity cutoff can be integrated into multi-band detectors as described in this paper.

[0111] like Figure 1 The diagram depicts and illustrates a measurement channel comprising a polarizer on the illumination side and an analyzer on the collection side. However, generally, it should be considered that any measurement channel may include or not include any combination of an illumination polarizer, a collection analyzer, an illumination compensator, and a collection compensator to perform measurements of the polarized reflectance of a sample, the unpolarized reflectance of a sample, or both.

[0112] In some embodiments, in addition to different wavelength ranges and incident angles, one or more measurement channels of the metrology system are configured to measure the wafer at different azimuth angles. In some embodiments, a metrology system comprising an infrared spectrometer as described herein is configured to perform wafer measurements at azimuth angles of 0 degrees and 90 degrees relative to the metrology target. In some embodiments, the metrology system is configured to simultaneously measure the wafer reflectivity within one or more wavelength ranges, one or more AOI ranges, and one or more azimuth angles. In some embodiments, the metrology system utilizes one or more coherent illumination sources selected from one or more spectral ellipsometers, spectral reflectometers, discrete wavelength ellipsometers, rotating polarizer ellipsometers, rotating compensator ellipsometers, rotating polarizer-rotating compensator ellipsometers, Miller matrix ellipsometers, or any combination thereof.

[0113] In another aspect, the size of the illumination pupil aperture and the size of the collection mask are adjusted to optimize the resulting measurement accuracy and speed based on the properties of the target being measured.

[0114] In another aspect, the size of the illumination field of view aperture is adjusted to achieve the desired spectral resolution for each measurement application.

[0115] In some examples, such as if the sample is an extremely thick film or grating structure, the illumination field-of-view aperture projected onto the wafer plane in a direction perpendicular to the incident plane is adjusted to reduce the field-of-view size to increase spectral resolution. In other examples, such as if the sample is a thin film, the illumination field-of-view aperture projected onto the wafer plane in a direction perpendicular to the incident plane is adjusted to increase the field-of-view size to shorten measurement time without sacrificing spectral resolution.

[0116] exist Figure 1 In the embodiment depicted, computing system 130 is configured to receive a signal 154 indicating a spectral response detected by the detector subsystem. Computing system 130 is further configured to determine a control signal 119 to be passed to programmable illumination field-of-view diaphragm 117. Programmable illumination field-of-view diaphragm 117 receives control signal 119 and adjusts the size of the illumination aperture to achieve a desired illumination field-of-view size.

[0117] In some examples, the illumination field of view (APV) is adjusted to optimize measurement accuracy and speed, as described above. In another example, the APV is adjusted to prevent image cropping by the spectrometer slit and corresponding degradation of the measurement results. In this way, the APV size is adjusted so that the image of the measurement target does not fill the spectrometer slit. In one example, the APV is adjusted so that the projection of the polarizer slit of the illumination optics does not fill the spectrometer slit of the metrology system. In another example, the APV is adjusted so that the projection of the polarizer slit of the illumination optics fills the spectrometer slit of the metrology system.

[0118] Figure 11 The diagram illustrates a method 400 for performing spectral measurements using angle-resolved detection in at least one novel aspect. Method 400 is suitable for applications using, for example, those described in this invention. Figure 1 and 2 The metrology systems 100 and 200 illustrated herein are used for implementation. In one aspect, it should be appreciated that the data processing block of method 400 can be implemented via a pre-programmed algorithm, which is executed by one or more processors of computing system 130 or any other general-purpose computing system. It should be understood herein that the specific structural aspects of metrology systems 100 and 200 are not intended to be limiting and should only be interpreted as illustrative.

[0119] In box 401, a certain amount of illumination light is guided from the illumination source to the measurement spot on the surface of the sample being measured within the incident angle range defined by the illumination numerical aperture (NA).

[0120] In box 402, a certain amount of collected light is collected from a measurement spot on the surface of the sample within a collection angle range defined by the collection NA. The collection angle range corresponds to at least a portion of the incident angle range.

[0121] In box 403, a certain amount of collected light is dispersed according to a wavelength across one direction of the two-dimensional planar surface of the detector and according to a collection angle across the same two-dimensional planar surface of the detector. This allows for the simultaneous readout of both wavelength-resolved and collection angle-resolved signals from the measurement sample.

[0122] In frame 405, a certain amount of collected light is resolved into at least ten collection angle sub-ranges according to the collection angle. Each sub-range is resolved under a detector NA, which is a fraction of the collection NA.

[0123] In yet another embodiment, systems 100 and 200 include one or more computing systems 130 for performing measurements of the actual device structure based on spectral measurement data collected according to the methods described herein. The one or more computing systems 130 are communicatively coupled to a spectrometer. In one aspect, the one or more computing systems 130 are configured to receive measurement data associated with measurements of the structure of the sample being measured.

[0124] It should be recognized that one or more steps described throughout this invention can be performed by a single computer system 130 or (alternatively) multiple computer systems 130. Furthermore, different subsystems of system 100 may include computer systems suitable for performing at least a portion of the steps described herein. Therefore, the foregoing description should not be construed as limiting the invention but is merely illustrative.

[0125] Additionally, the computer system 130 can be communicatively coupled to the spectrometer in any manner known in the art. For example, one or more computing systems 130 may be coupled to a computing system associated with the spectrometer. In another example, the spectrometer may be directly controlled by a single computer system coupled to the computer system 130.

[0126] The computer system 130 of the metering system 100 can be configured to receive and / or acquire data or information from subsystems of the system (e.g., spectrometers, etc.) via a transmission medium that may include wired and / or wireless portions. In this way, the transmission medium can be used as a data link between the computer system 130 and other subsystems of the system 100.

[0127] The computer system 130 of metrology systems 100 and 200 can be configured to receive and / or acquire data or information (e.g., measurement results, modeling inputs, modeling results, reference measurement results, etc.) from other systems via a transmission medium that may include wired and / or wireless components. In this way, the transmission medium can serve as a data link between the computer system 130 and other systems (e.g., on-board metrology system 100, external memory, or other external systems). For example, the computer system 130 can be configured to receive measurement data from a storage medium (i.e., memory 132 or external memory) via a data link. For example, spectral results obtained using the spectrometer described herein can be stored in a permanent or semi-permanent memory device (e.g., memory 132 or external memory). In this respect, spectral results can be received from on-board memory or from an external memory system. Furthermore, the computer system 130 can transmit data to other systems via the transmission medium. For example, a measurement model determined by the computer system 130 or estimated parameter values ​​171 can be transferred and stored in external memory. In this respect, the measurement results can be transmitted to another system.

[0128] The computing system 130 may include, but is not limited to, personal computer systems, mainframe computer systems, workstations, graphics computers, parallel processors, or any other means known in the art. Generally, the term "computing system" may be broadly defined to encompass any means having one or more processors that execute instructions from a memory medium.

[0129] The program instructions 134 for implementing methods such as those described herein can be transmitted via a transmission medium (e.g., a wire, cable, or wireless transmission link). For example, such as Figure 1 As illustrated in the diagram, program instructions 134 stored in memory 132 are transferred to processor 131 via bus 133. Program instructions 134 are stored in a computer-readable medium (e.g., memory 132). Exemplary computer-readable media include read-only memory, random access memory, magnetic disk or optical disk, or magnetic tape.

[0130] In some examples, the measurement model was implemented as a component of the SpectraShape® optical critical size metrology system, available from KLA-Tencor Corporation in Milpitas, California, USA. In this way, the model was built and ready for immediate use after the spectrum was collected by the system.

[0131] In some other examples, the measurement model is implemented offline, for instance, by a computing system using AcuShape® software available from KLA Corporation in Milpitas, California, USA. The resulting trained model can then be incorporated as a component of an AcuShape® library accessible to the metrology system performing the measurement.

[0132] In another aspect, the methods and systems for spectrometric measurements of semiconductor devices described herein are applied to the measurement of high aspect ratio (HAR) structures, large lateral dimension structures, or both. The described embodiments enable optical critical dimension (CD), film, and composition metrology of semiconductor devices comprising three-dimensional NAND structures, such as vertical NAND (V-NAND) structures, dynamic random access memory (DRAM) structures, etc., manufactured by various semiconductor manufacturers such as Samsung (Korea), SK Hynix (Korea), Toshiba (Japan), and Micron Technology (USA). These complex devices suffer from low light transmittance into the structure being measured. Figure 3 An exemplary high aspect ratio structure 160 is depicted, exhibiting low light transmittance into the measured structure. Broadband AOI, azimuth, or both spectral ellipsometers (with simultaneous spectral band detection as described herein) with wide-range capabilities and spectral range are suitable for measuring these high aspect ratio structures. HAR structures typically include a hard mask layer to facilitate the HAR etching process. As described herein, the term "HAR structure" refers to any structure characterized by an aspect ratio greater than 2:1 or 10:1 and potentially up to 100:1 or higher.

[0133] In another aspect, the measurement results described herein can be used to provide active feedback to process tools (e.g., lithography tools, etching tools, deposition tools, etc.). For example, values ​​of measured parameters determined based on the measurement methods described herein can be passed to the lithography tool to adjust the lithography system to achieve the desired output. Similarly, etching parameters (e.g., etching time, diffusion rate, etc.) or deposition parameters (e.g., time, concentration, etc.) can be included in the measurement model to provide active feedback to the etching or deposition tool, respectively. In one example, corrections to process parameters determined based on the measured device parameter values, as well as the trained measurement model, can be passed to the lithography tool, etching tool, or deposition tool.

[0134] As described herein, the term "critical dimension" includes any critical dimension of a structure (e.g., bottom critical dimension, middle critical dimension, top critical dimension, sidewall angle, grating height, etc.), any critical dimension between two or more structures (e.g., distance between two structures), and displacement between two or more structures (e.g., overlap displacement between overlapping grating structures, etc.). Structures may include three-dimensional structures, patterned structures, stacked structures, etc.

[0135] As described herein, the terms “critical size application” or “critical size measurement application” include any critical size measurement.

[0136] As described herein, the term "metrology system" includes any system used at least in part to characterize a sample in any respect, including measurement applications such as critical size metrology, stacking metrology, line tilt or center (CLS) shift metrology, critical size and spacing deformation metrology, focus / dose metrology, film thickness metrology, and composition metrology. However, such technical terms do not limit the scope of the term "metrology system" as described herein. Additionally, metrology system 100 may be configured for measurements on patterned wafers and / or unpatterned wafers. The metrology system may be configured as an LED inspection tool, edge inspection tool, backside inspection tool, macroscopic inspection tool, or multi-mode inspection tool (involving data from one or more platforms simultaneously), and any other metrology or inspection tool that benefits from angle-resolved NA collection.

[0137] This document describes various embodiments of semiconductor measurement systems (e.g., inspection systems or lithography systems) that can be used to measure samples within any semiconductor processing tool. The term "sample" is used herein to refer to a wafer, a photomask, or any other sample that can be processed by means known in the art (e.g., printing or inspecting for defects).

[0138] As used herein, the term "wafer" generally refers to a substrate formed of semiconductor or non-semiconductor materials. Examples include, but are not limited to, single-crystal silicon, gallium arsenide, and indium phosphide. Such substrates are typically found and / or processed in semiconductor fabrication facilities. In some cases, a wafer may consist only of a substrate (i.e., a bare wafer). Alternatively, a wafer may contain one or more layers of different materials formed on the substrate. The one or more layers formed on the wafer may be "patterned" or "unpatterned." For example, a wafer may contain multiple bare wafers with repeatable pattern features.

[0139] A "photomask" can be a photomask at any stage of the photomask fabrication process, or it can be a finished photomask that may or may not be released for use in a semiconductor fabrication facility. A photomask or "mask" is generally defined as a substantially transparent substrate on which substantially opaque areas are formed and configured as patterns. For example, the substrate may comprise a glass material such as amorphous SiO2. During the exposure step of the photolithography process, the photomask can be placed over a resist-covered wafer such that the pattern on the photomask can be transferred to the resist.

[0140] One or more layers formed on a wafer can be patterned or unpatterned. For example, a wafer may comprise multiple dies, each having repeatable pattern features. The formation and processing of such material layers can ultimately produce a finished device. Many different types of devices can be formed on a wafer, and the term wafer, as used herein, is intended to encompass wafers on which any type of device known in the art is fabricated.

[0141] In one or more exemplary embodiments, the described functionality may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functionality may be stored as one or more instructions or code on or transmitted via a computer-readable medium. A computer-readable medium includes both computer storage media and communication media, encompassing any medium that facilitates the transfer of a computer program from one place to another. A storage medium may be any available medium accessible by a general-purpose or special-purpose computer. By way of example and not limitation, such computer-readable media may include: RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage devices or other magnetic storage devices, or any other medium that can be used to carry or store desired program code elements in the form of instructions or data structures and is accessible by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. Furthermore, any connection may be properly referred to as a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology (such as infrared light, radio, and microwave), then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology (such as infrared light, radio, and microwave) are all included within the definition of media. As used herein, disks and platters include optical discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically, while platters reproduce data optically using lasers. The combinations above should also be included within the scope of computer-readable media.

[0142] Although some specific embodiments have been described above for illustrative purposes, the teachings of this patent document are generally applicable and not limited to the specific embodiments described above. Therefore, various modifications, adaptations, and combinations of the various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.

Claims

1. A spectrometric system, comprising: One or more illumination sources are configured to generate a certain amount of illumination light, which is incident on a measurement spot on the surface of the sample being measured at a nominal angle of incidence and an angle of incidence range defined by the numerical aperture of the illumination. A collection optics subsystem configured to collect a certain amount of collected light from the measurement spot on the surface of the sample within a collection angle range corresponding to at least a portion of the incident angle range, the collection optics subsystem comprising: a collection mask disposed at or near the pupil plane of the collection optics subsystem, wherein the collection mask selects the certain amount of collected light within the collection angle range defined by the collection numerical aperture (NA); And a dispersive element, wherein the dispersive element causes the collected light to disperse according to wavelength; as well as At least one detector having a planar two-dimensional surface sensitive to incident light, the at least one detector being configured to detect the amount of collected light and generate an output signal indicating the detected light, wherein the amount of collected light is dispersed onto the at least one detector by the collecting optics subsystem according to a wavelength along a direction of the at least one detector and according to a collection angle within the collection angle range along a second direction of the at least one detector, wherein the first direction is orthogonal to the second direction, wherein the collection angle range dispersed along the second direction is resolved into at least ten collection angle sub-ranges, each collection angle sub-range being at the detector numerical aperture (NA), the detector NA being a fraction of the collection NA.

2. The spectrometer system of claim 1, wherein the detector NA associated with each of the at least ten collection sub-ranges is less than 0.

010.

3. The spectral metrology system according to claim 1, wherein the one or more illumination sources comprise spatially and temporally coherent light sources.

4. The spectral metrology system according to claim 3, wherein the spatially and temporally coherent light source is a supercontinuum laser light source.

5. The spectral metrology system according to claim 1, wherein the amount of illumination light comprises wavelengths in the range of greater than 400 nanometers and less than 2,500 nanometers.

6. The spectral metrology system according to claim 1, wherein the maximum width of the measurement spot is less than 70 micrometers.

7. The spectral metrology system according to claim 1, wherein the illumination numerical aperture (NA) of the illumination source at the measurement spot is less than 0.

15.

8. The spectral metrology system according to claim 1, wherein the collection NA of the collection optical device subsystem at the measurement spot is at least 0.02 and less than 0.

15.

9. The spectrometer system of claim 1, wherein the at least one detector comprises two or more detectors, wherein each of the two or more detectors detects a portion of the collected light within a different spectral range.

10. The spectrometer system of claim 7, wherein each of the two or more detectors simultaneously detects each portion of the collected light in different spectral ranges.

11. The spectrometric system of claim 1, wherein the at least one detector comprises two or more distinct surface regions, each having a different photosensitivity, wherein the two or more distinct surface regions are aligned with the wavelength dispersion direction across the surface of the at least one detector.

12. The spectrometric system according to claim 1, wherein the measured sample comprises a three-dimensional NAND structure or a dynamic random access memory (DRAM) structure.

13. The spectrometer system according to claim 1, further comprising: A movable optical element is positioned in the illumination optical path between the coherent illumination source and the measurement spot, wherein the movable optical element causes the amount of illumination light to scan over the measurement spot at a frequency at least ten times the detection frequency of the at least one detector.

14. A method comprising: Within the incident angle range defined by the illumination numerical aperture (NA), a certain amount of illumination light from the illumination source is guided to the measurement spot on the surface of the sample being measured; A certain amount of collected light from the measurement spot on the surface of the sample is collected within a collection angle range defined by the collection NA, the collection angle range corresponding to at least a portion of the incident angle range; The collected light is dispersed according to a wavelength across a two-dimensional planar surface of the detector in one direction and according to a collection angle across the two-dimensional planar surface of the detector in a second direction. and The collected light is divided into at least ten collection sub-ranges based on the collection angle, and each collection sub-range is under the detector NA, which is the fraction of the collection NA.

15. The method of claim 14, wherein the detector NA associated with each of the at least ten collection slot ranges is less than 0.

010.

16. The method of claim 14, wherein the amount of illumination light is spatially and temporally coherent.

17. The method of claim 14, wherein the amount of illumination light comprises wavelengths in the range of greater than 400 nanometers and less than 2,500 nanometers.

18. The method of claim 14, wherein the collected NA is at least 0.02 and less than 0.

15.

19. The method of claim 14, further comprising: The specified amount of illumination light is scanned over the measurement light spot at a frequency at least ten times the detection frequency of the specified amount of collected light.

20. A spectrometric system comprising: A lighting source, configured to produce a certain amount of illumination light; An illumination optics subsystem is configured to direct a certain amount of illumination light from the illumination source onto a measurement spot on the surface of the sample being measured within an incident angle range defined by the illumination numerical aperture (NA). A reflective collecting optical device subsystem is configured to collect a certain amount of collected light from the measuring light spot on the surface of the sample within a collection angle range defined by the collection NA; At least one detector having a planar two-dimensional surface sensitive to incident light, the at least one detector being configured to detect a certain amount of collected light according to a wavelength along one direction of the planar two-dimensional surface and according to a collection angle along another direction of the planar two-dimensional surface, wherein the detector resolves the certain amount of collected light detected according to the collection angle into at least ten collection angle sub-ranges, each collection angle sub-range being under the detector NA, the detector NA being a fraction of the collection NA.

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