Optical Techniques for Materials Characterization

Abstract

A polarized Raman spectroscopy system for defining parameters of a polycrystalline material, the system comprising a polarized Raman spectrometer, a computer-controlled sample stage for positioning a sample at different locations, and a computer comprising a processor and associated memory. The polarized Raman spectrometer generates signals from small-sized spots at multiple locations on the sample or from elongated linear points on the sample, and the processor analyzes the signals to define the parameters of the polycrystalline material.

Description

Technical Field

[0001] The present invention relates to systems and methods for characterizing crystalline materials. More particularly, the present invention relates to systems and methods for defining parameters of crystalline materials. Background Art

[0002] Polycrystalline materials are a widespread form of matter with important practical applications in many industries. To ensure the proper properties of polycrystalline materials, precise measurement and control of the grain size is often required. A clear example of this is the use of polycrystalline materials in the semiconductor industry, where polycrystalline materials are used in numerous process steps and have a variety of functions for front-end, back-end, logic and memory products.

[0003] Polycrystalline materials are made up of multiple nanocrystals ("grains"), each of which consists of the atomic structure of a perfect crystal, but with different orientations. The average size of these grains can affect the material's properties, such as electrical conductivity, phase diagram, thermal response, mechanical behavior, and can also affect the overall performance of a device.

[0004] Unfortunately, the determination of average grain size is a complex technical task that usually requires the use of destructive techniques (such as transmission electron microscopy), which, in addition to being destructive and extremely slow, can only sample extremely small areas (a few micrometers) at a time, which prevents good statistical feedback.

[0005] Another useful method is X-ray diffraction (XRD). However, the results of XRD are highly qualitative and considered to be imprecise, and are often very difficult to interpret.

[0006] Therefore, there is a need for a rapid, non-destructive technique that can be used for in-line metrology to allow the determination of grain size. Summary of the invention

[0007] The present invention provides a polarized Raman spectroscopy system and method for defining polycrystalline material parameters through (a) dedicated hardware configuration, (b) specific measurement sequence and (c) interpretation method.

[0008] The present invention relies on the fact that the polarized Raman spectrum of crystalline materials is extremely sensitive to the crystal orientation, since the intensity of the polarized Raman signal depends strongly on the orientation of the crystal.

[0009] Therefore, according to some embodiments of the present invention, a polarized Raman spectroscopy system for defining parameters of a polycrystalline material is provided. The system comprises:

[0010] Polarized Raman Spectrometer,

[0011] A computer-controlled sample stage for positioning the sample at different locations, and

[0012] A computer comprising a processor and associated memory,

[0013] Therein, a polarized Raman spectrometer generates signals from small-sized spots at multiple locations on the sample or from thin, linear spots on the sample, and a processor analyzes the signals to define parameters of the polycrystalline material.

[0014] Furthermore, according to some embodiments of the present invention, one of the parameters of the polycrystalline material is the average grain size.

[0015] Furthermore, according to some embodiments of the present invention, a polarized Raman spectrometer for generating a signal from an elongated linear spot comprises:

[0016] - a light source for generating the light beam,

[0017] - a detection unit comprising a spectrometer,

[0018] - an optical system consisting of a plurality of lenses, including an objective lens and a line-spot element, for forming an illumination spot so as to project an elongated line-shaped spot onto the sample,

[0019] - A 2-D image sensor connected to the spectrometer, which receives the elongated line-shaped spots from the spectrometer and creates a two-dimensional image of the line directly related to the spots on the sample.

[0020] Furthermore, according to some embodiments of the present invention, the line-spot element is selected from the group consisting of a cylindrical lens, a holographic optical element, and a microlens array.

[0021] Furthermore, according to some embodiments of the present invention, the optical system is of high numerical aperture (NA) to allow collection of signals from multiple locations in a single measurement.

[0022] Furthermore, according to some embodiments of the present invention, the numerical aperture is adjustable to change the size of the elongated linear spots on the sample.

[0023] In addition, according to some embodiments of the present invention, the processor uses the 2-D image of the line created by the 2-D image sensor to: (i) retrieve Raman peaks from the 2-D image of the line; (ii) generate a Raman amplitude distribution; (iii) determine the intensity of the Raman peak associated with the material; (iv) calculate the standard deviation based on the Raman amplitude distribution of the Raman peak; and (v) calculate the average grain size therefrom.

[0024] Furthermore, according to some embodiments of the present invention, a polarized Raman spectrometer for generating signals from small spots at multiple locations of a sample comprises:

[0025] - a light source for generating the light beam,

[0026] - a detection unit comprising a spectrometer, and

[0027] -An optical system consisting of multiple lenses including an objective lens.

[0028] Furthermore, according to some embodiments of the present invention, the optical system is of high numerical aperture (NA) resulting in a small spot size.

[0029] Furthermore, according to some embodiments of the present invention, the numerical aperture is adjustable to change the size of a small-sized spot on the sample.

[0030] Furthermore, according to some embodiments of the present invention, the numerical aperture may be adjusted by a variable aperture located at the back focal plane of the objective lens.

[0031] Furthermore, according to some embodiments of the present invention, the sample stage is translated along the XY axis for positioning the sample at multiple positions, thereby collecting signals from multiple positions of the small spot.

[0032] Furthermore, according to some embodiments of the present invention, a scanning beam can collect signals from small spots at multiple locations on a sample.

[0033] In addition, according to some embodiments of the present invention, the processor uses the signal detected by the detection unit to (i) retrieve a Raman peak from a 2-D image of the line; (ii) generate a Raman amplitude distribution; (iii) determine the intensity of the Raman peak associated with the material; (iv) calculate a standard deviation based on the Raman amplitude distribution of the Raman peak; and (v) calculate an average grain size therefrom.

[0034] In addition, according to some embodiments of the present invention, a method for defining parameters of a polycrystalline material is provided. The method comprises:

[0035] (i) providing a polarized Raman spectroscopy system as described above,

[0036] (ii) generating multiple signals from small spots at multiple locations on the sample or from thin linear spots on the sample, and

[0037] (iii) Analyzing multiple signals to define parameters of the polycrystalline material.

[0038] Furthermore, according to some embodiments of the present invention, the method includes defining an average grain size of the polycrystalline material.

[0039] Furthermore, according to some embodiments of the present invention, generating signals from small spots at multiple locations includes translating the sample stage along an XY axis of the stage to position the sample at multiple locations to collect signals from multiple locations on the sample.

[0040] Furthermore, according to some embodiments of the present invention, generating signals from a small spot at a plurality of locations comprises scanning a light beam to collect signals from a plurality of locations on the sample.

[0041] In addition, according to some embodiments of the present invention, when the signal is generated from an elongated linear point on the sample, the method further includes: (i) creating a 2-D image of the line, (ii) retrieving a Raman peak from the 2-D image of the line; (iii) generating a Raman amplitude distribution; (iii) determining the intensity of the Raman peak associated with the material; (iv) calculating a standard deviation based on the Raman amplitude distribution of the Raman peak; and (v) calculating the average grain size therefrom.

[0042] In addition, according to some embodiments of the present invention, when signals are generated from small spots at multiple locations on a sample, the method further includes: (i) detecting the signal, (ii) retrieving a Raman peak from the signal; (ii) generating a Raman amplitude distribution; (iii) determining the intensity of the Raman peak associated with the material; (iv) calculating a standard deviation based on the Raman amplitude distribution of the Raman peak; and (v) calculating an average grain size based thereon. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The disclosed embodiments will be more fully understood from the following detailed description in conjunction with the accompanying drawings. The drawings included and described herein are schematic and do not limit the scope of the disclosure. It should also be noted that in the drawings, the sizes of some elements may be exaggerated and therefore are not drawn to scale for illustrative purposes. The sizes and relative sizes do not necessarily correspond to actual reductions in the implementation of the present disclosure.

[0044] Figure 1A and Figure 1B The large size of the grains is shown by Raman imaging.

[0045] FIG. 2A to FIG. 2D The principles of a system and method for detecting average grain size according to some embodiments of the present invention are illustrated.

[0046] Figure 3 is a schematic diagram of a computerized method for detecting average grain size according to some embodiments of the present invention.

[0047] FIG. 4A to FIG. 4D A polarized Raman spectrometer for performing a single spatially resolved Raman measurement at a set of sample points on a sample according to some embodiments of the present invention is shown.

[0048] Figure 5 is a schematic diagram of a computerized method for probing average grain size by performing a single spatially resolved Raman measurement at a set of sample points on a sample according to some embodiments of the present invention. DETAILED DESCRIPTION

[0049] In the following description, various aspects of the present application will be described. For the purpose of illustration, specific configurations and details are set forth to provide a thorough understanding of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented without the specific details presented herein. In addition, well-known features may be omitted or simplified to avoid confusing the present application.

[0050] The term "comprising" as used in the claims is "open ended" and refers to the elements listed, or their equivalent in structure or function, and any other elements not listed. It should not be interpreted as limiting the means listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as indicating the presence of the referenced features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components, or combinations thereof. Thus, the scope of the expression "a system comprising x and z" should not be limited to systems consisting only of x and z. Likewise, the scope of the expression "a method comprising steps x and z" should not be limited to methods consisting only of these steps.

[0051] As used herein, the term "and / or" includes any and all combinations of one or more associated listed items. Unless otherwise specified, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by ordinary technicians in the field to which the invention belongs. In addition, terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their context in the specification and related technology, and should not be interpreted in an idealized or overly formal manner unless otherwise explicitly stated herein. For the sake of brevity and / or clarity, well-known functions or constructions are not described in detail.

[0052] It should be understood that when an element is referred to as being "on," "attached to," "connected to," "coupled to," "contacting," etc., another element, it can be directly on, attached to, connected to, coupled to, or contacting the other element, or there can be intervening elements. In contrast, when an element is referred to as being, for example, "directly on," "directly attached to," "directly connected to," "directly coupled to," or "directly contacting" another element, there are no intervening elements. Those skilled in the art will recognize that references to structures or features that are disposed "adjacent" to another feature can have portions that overlap or are located near the adjacent feature.

[0053] Figure 1A and Figure 1B Raman imaged large grains are shown, with grains larger than ~1 μm. These figures show a polycrystalline material consisting of multiple regions, each organized as a crystalline domain, but with different orientations (crystalline orientation is depicted as the direction of lines inside the grain regions).

[0054] When the grains are large enough to be optically resolved, polarized Raman images can be taken to provide a direct map of the grain orientation, as shown in the figure. By properly choosing the illumination and collection polarizations, the Raman signal can be tuned to be highly sensitive to the crystal orientation.

[0055] However, there are almost always cases where the grain size is significantly smaller than the optical resolution, which prevents this direct approach.

[0056] Therefore, the present invention provides a polarized Raman spectrometric system and method for resolving and defining parameters of grains smaller than 1 μm.

[0057] A polarized Raman spectroscopy system according to some embodiments of the present invention comprises a polarized Raman spectrometer, a computer-controlled sample stage for placing samples at different positions, and a computer including a processor and associated memory.

[0058] The polarization Raman spectrometer includes: a light source for generating a light beam, a detection unit including a spectrometer, and an optical system composed of a plurality of lenses including an objective lens.

[0059] According to some embodiments of the invention, the instrument further comprises a plurality of polarizers for polarizing the illumination beam and the detection beam.

[0060] According to some embodiments of the present invention, in order to collect signals at multiple locations on the sample, the sample stage is translated along the XY axis to position the sample at multiple locations, or the point illumination is scanned across the sample.

[0061] FIG. 2A to FIG. 2D The principles behind a system and method for detecting average grain size according to some embodiments of the present invention are shown.

[0062] Figure 2A and Figure 2B The case of large grains is shown, i.e., grains of comparable size to the illumination spot size 202. In this case, at each measurement location, a small number of grains (e.g., grains in the darker regions 204A to 204D) contribute to the measurement signal 206. Figure 2B As shown, the Raman signal changes significantly due to the grain size being comparable to the illumination spot size 202, and therefore the measurements are averaged over a small number of grain orientations.

[0063] Figure 2C and Figure 2DThe case of small-sized grains is shown, i.e., the grains are much smaller than the illumination spot size 208. In this case, each measurement is averaged over many grain orientations in regions 210A to 210D. Therefore, the Raman signal 208 shows little variation about its average, and the grain size can be inferred from the signal variance.

[0064] Figure 3 is a schematic diagram of a computerized method 300 for detecting average grain size using a processor and associated memory according to some embodiments of the present invention.

[0065] According to some embodiments of the present invention, method 300 is based on point illumination that scans across the entire sample one point at a time with relatively high resolution and without crosstalk between measurements.

[0066] The method 300 comprises the following steps:

[0067] Step 302 - Providing a Raman spectroscopy system. According to some embodiments of the present invention, the Raman spectroscopy system is provided with a high numerical (NA) aperture optical system to allow efficient collection of Raman signals from multiple locations.

[0068] Step 304 - Run a high-resolution polarized Raman measurement on any set of points distributed spatially on the sample, obtain Raman peaks at these points, and use a standard peak fitting algorithm to provide a Raman amplitude distribution.

[0069] Step 306 - Determine the intensity of the Raman peak associated with the material of the test sample.

[0070] Step 308 - Calculate the standard deviation of the Raman amplitude distribution.

[0071] Step 310: derive the average grain size according to the standard deviation of the Raman amplitude distribution.

[0072] Standard statistical analysis gives an estimate of the average grain size:

[0073]

[0074] For a given crystal type, the Raman intensity is given by the Raman selection rule as follows:

[0075]

[0076] The exact value of the scaling factor depends on the assumption of completely random grain orientation and the resulting Raman intensity distribution.

[0077] is the so-called Raman tensor associated with each vibrational mode, e i，sis the incident and scattered electric field polarization. For each grain in a polycrystalline material, the Raman tensor is rotated according to its orientation.

[0078] If the orientation is given by the rotation matrix If , then the strength of the grain as a whole can be determined as follows:

[0079]

[0080] Among them I g is the intensity of the illumination point at the corresponding grain.

[0081] By summing, the spatial distribution of the spots and the orientation distribution of the grains can be related to the observed intensity distribution and, therefore, to the specific relationship between the observed relative variance and grain size.

[0082] It should be noted that a correction to this estimator can be obtained by a one-time calibration - a sample with known grain size can be measured and the proportionality constant between the Raman signal variance and grain size can be accurately obtained to account for arbitrary uncertainties in the illumination spot shape or other system parameters.

[0083] According to some embodiments of the present invention, the following are several specific system aspects essential to the method:

[0084] -Numerical Aperture (NA):

[0085] (a) A high numerical aperture is necessary to allow efficient collection of Raman signals within a short acquisition time. In the present context, a high NA also results in a small spot size, as shown by the diffraction:

[0086]

[0087] where λ is the wavelength. Therefore, a high NA can characterize small grain sizes.

[0088] It should be noted that Equation 4 is simplified for clarity - for Raman metrology, the illumination and collection wavelengths are slightly different, and the illumination and collection NAs may be different.

[0089] (b) Controlling the illumination NA and / or the collection NA affects the measured spot size, i.e. the number of grains within the spot can be changed and thus the grain statistics. Specifically, measurements can be performed at a set of different NA values ​​(illumination and / or collection), where for each configuration the spot size can be calculated and the grain size can be derived from Eq. 1.

[0090] This method provides an alternative to the discussed method of scanning a spot over different locations and may be advantageous in situations where the structure to be measured is located in a small area which prevents such a scanning method.

[0091] According to some embodiments of the present invention, this approach can be implemented by placing a variable aperture at the back focal plane of the objective (in the illumination and / or collection path) and controlled electronically.

[0092] - Another implementation that is directly beneficial for the measurement is to use multi-wavelength Raman spectroscopy. By using a set of different excitation wavelengths, the spot size can be varied (see equation 2). Therefore, using a set of measurements with different spot sizes (e.g. controlled by the excitation wavelength), it is possible to analyze how the Raman signal varies with different grain statistics and derive an average grain size.

[0093] -Another implementation to improve throughput and performance is angle-resolved Raman spectroscopy. By controlling the illumination incident angle, and separating the collected signals from different scattering angles, multiple views of the same spot can be recorded and combined to collect more information from a single measurement, reducing the number of measurements required as well as improving measurement stability.

[0094] According to some embodiments of the present invention, a particularly useful optical arrangement in the method is to use single-shot spatially resolved Raman imaging. The method involves the following:

[0095] The illumination spot should be shaped so that it projects a thin line on the sample. This can be achieved by adding a “line-spot” element, such as a cylindrical lens, holographic optical element, microlens array or others.

[0096] The "line-spot" element is aligned so that the elongated direction point is along or close to the spectrometer slit direction. Thus, the signal measured on a 2-D sensor (e.g., a spectrometer charge coupled device (CCD)) involves a set of Raman spectra corresponding to different positions along the illumination spot.

[0097] The 2-D image on the spectrometer CCD is registered. Each CCD line has a Raman spectrum corresponding to a different location on the sample.

[0098] According to some embodiments of the invention, this enables acquisition of Raman spectra from multiple positions in one measurement without any movement of the sample or scanning of the illumination point across the sample, and the grain size can be derived from the statistical distribution of these different Raman spectra.

[0099] Figure 4 and Figure 5 Some implementations are shown.

[0100] FIG. 4A to FIG. 4D A polarized Raman spectrometer 400 for performing a single spatially resolved Raman measurement at a set of sample points on a sample according to some embodiments of the present invention is shown.

[0101] The Raman spectroscopy system 400 includes a light source 402, a detection unit including a spectrometer 404, an optical system 406 (configured as a light guiding device for guiding light from the light source 402 to a sample 408 and guiding returned light from the sample 408 to the spectrometer 404), and a single or multiple polarizers (not shown in the figure) for polarizing the illumination beam and the detection beam.

[0102] The optical system 406 includes the line-spot element 210 , a beam splitter 412 , an objective unit 414 (one or more lenses), and a focusing lens 416 .

[0103] The spectrometer 404 generates spectral data of light incident thereon, and the output of the spectrometer 404 may be transmitted to a computer via wired or wireless communication (eg, Wi-Fi or Bluetooth or a combination thereof).

[0104] Figure 4A 4 is a schematic diagram of an illumination path in a Raman spectroscopy system 400 according to some embodiments of the present invention. As shown in the figure, a laser beam 420 generated by a light source 402 passes through a “line-spot” element 410 to generate an elongated line-spot 422 on a sample 408.

[0105] The "line-spot" element 410 may be selected from a cylindrical lens, a holographic optical element, a microlens array or any other suitable optical element.

[0106] like Figure 4A As shown, the "line-spot" element 410 produces a beam divergence in one axis while leaving the beam 420 unaffected in the other axis to form an elongated line-spot 422 on the sample 408. The beam splitter 412 reflects the beam toward the objective lens unit 414, which focuses the beam on the sample 408. As shown, due to the divergence of the beam in one axis, an elongated line-spot 422 is produced on the sample 408.

[0107] Figure 4B 4 is a schematic diagram of a collection path according to some embodiments of the present invention. As shown, light emitted from sample 408 passes through objective lens unit 414 and beam splitter 412, and is focused by focusing lens 416 onto spectrometer slit 430 of spectrometer 404. In this layout, linear points 422 on sample 408 are imaged onto spectrometer slit 430, such as linear points 432, schematically illustrating the imaging layout. Figure 4C Spectrometer 404 is shown in FIG. Figure 4D Sample 408 is shown in FIG. Figure 4C As shown, line-shaped spots 432 on spectrometer slit 430 are spectrally resolved to produce a 2D image 436 on CCD 438. Thus, image 436 is directly related to line-shaped spots 422 on sample 408.

[0108] According to some embodiments of the invention, the 2D image 436 produces a position-dependent spectrum, eg, one axis corresponds to wavelength and the other axis corresponds to position on the sample.

[0109] Figure 4D The measured sample 408 is shown in FIG. As shown, different portions of the line-shaped dots 432 are imaged onto different lines of the CCD 438, where they can be read and analyzed separately.

[0110] Figure 5 is a schematic diagram of a computerized method 500 for detecting average grain size by performing a single spatially resolved Raman measurement at a set of sample points on a sample, according to some embodiments of the present invention.

[0111] The method 500 comprises the following steps:

[0112] Step 502: Provide FIG. 4A to FIG. 4D According to some embodiments of the present invention, the Raman spectrometer is equipped with a high numerical (NA) aperture optical system to allow efficient collection of Raman signals from multiple positions in a single measurement and in a relatively short acquisition time.

[0113] Using this embodiment, Raman spectra can be acquired from multiple positions in one measurement, without requiring any movement of the measurement points or the sample, and the grain size is derived from the statistical distribution of these different Raman spectra.

[0114] Step 504 - using the Raman spectroscopy system to form a thin line of spots on the sample.

[0115] The line of spots is aligned along or close to the direction of the spectrometer slit. The measured signal on the spectrometer CCD therefore involves a set of Raman spectra corresponding to different positions along the illuminated spot.

[0116] Step 506 - Run a high resolution polarized Raman measurement to generate a 2D image of the line directly associated with the line-shaped points on the sample and obtain the Raman peaks at these points. According to some embodiments of the present invention, it is not necessary to map an image of the probed area, but rather to make measurements at the sampled points. The measured values ​​should be close enough to represent local measurements where the average grain size is fixed.

[0117] Step 508 - Register the 2D image on the spectrometer CCD.

[0118] In contrast to standard Raman measurements, in this arrangement the 2D images on the spectrometer CCD are registered and each CCD line has a Raman spectrum corresponding to a different position on the sample.

[0119] Step 510 - Transmit data from the CCD to a computer via wired or wireless communication.

[0120] Step 512 - Use a standard peak fitting algorithm to provide a Raman amplitude distribution.

[0121] Step 514 - Determine the intensity of the Raman peak associated with the material of the test sample.

[0122] Step 516 - Calculate the standard deviation of the Raman amplitude distribution.

[0123] Step 518 - derive the average grain size from the standard deviation of the Raman amplitude distribution.

[0124] Statistical Accuracy:

[0125] According to some embodiments of the present invention, the accuracy of grain size estimation using the present system and method is determined by the size of the statistical set measured, i.e., the more measurement points are acquired, the better the statistical analysis is, and the more accurate the estimated grain size is. However, the size of the statistical set required for a particular degree of convergence depends on the grain size, i.e., larger grains result in larger statistical sets. This dependence may lead to measurement instability because the measurement performance may vary with sample characteristics.

[0126] Additionally, the variance of the measurements is affected by measurement errors such as photon shot noise and other noise sources. Such noise sources should be either negligible relative to the variance associated with the die (e.g., by controlling the acquisition time per position) or appropriately accounted for in the analysis.

[0127] According to some embodiments of the present invention, this error may be mitigated by analyzing the collected signal and noise during the measurement and estimating the statistical validity during data collection.

[0128] This way, standard statistical tests can be applied to the data and indicate whether additional measurements are needed. This approach may also help improve measurement throughput, as acquisitions are made only when needed, rather than "wasted" when statistics are satisfactory.

[0129] This approach and its variants enable:

[0130] -Non-contact, non-destructive measurement,

[0131] - small spots (<1-a few microns), allowing measurement of small areas,

[0132] - Potentially fast measurements: Although Raman metrology is much slower than standard optical scatterometry methods (e.g., ellipsometry, reflectometry), it can be much faster than X-ray or TEM-based methods. With the right choice of laser source and efficient optical layout and spectrometer, Raman metrology can become efficient - since the specific acquisition time depends strongly on the material being measured and its Raman cross section, the expected measurement time can be tens of seconds or even minutes.

[0133] It should be noted that the material under consideration must be a Raman active material that provides a distinct peak (or set of peaks) in the Raman spectrum, and the Raman signal can be tuned to be highly sensitive to crystal orientation by adjusting the illumination and collection polarization.

Claims

1. A polarized Raman spectroscopy system for defining parameters of a polycrystalline material, the system comprising: Polarized Raman Spectrometer, A computer-controlled sample stage for positioning the sample at different locations, and A computer comprising a processor and associated memory, wherein the polarized Raman spectrometer generates signals from small-sized spots at multiple locations on a sample or from elongated linear spots on the sample, and the processor analyzes the signals to define the parameters of the polycrystalline material; Wherein, the polarization Raman spectrometer is configured as: irradiating a plurality of locations of the polycrystalline material with a plurality of spots; wherein the polycrystalline material comprises grains; collecting radiation emitted from the plurality of spots; and generating a plurality of signals from the plurality of locations of the polycrystalline material; The computer is configured to: determining Raman peaks at the plurality of locations based on the plurality of signals; Determining the distribution of Raman amplitudes of the Raman peaks using a peak fitting algorithm; and The average size of the grains is determined based on the distribution of the Raman amplitude of the Raman peak.

2. The polarization Raman spectroscopy system according to claim 1, wherein: The polarization Raman spectrometer for generating the signal from the elongated linear spot comprises: - a light source for generating the light beam, - a detection unit comprising a spectrometer, - an optical system consisting of a plurality of lenses, including an objective lens and a line-spot element, for shaping the illumination spot so as to project said elongated linear spot onto said sample, - a 2-D image sensor connected to the spectrometer, which receives the elongated line-shaped points from the spectrometer and creates a 2D image of the line directly related to the points on the sample.

3. The polarization Raman spectroscopy system according to claim 2, wherein: The line-spot element is selected from the group consisting of a cylindrical lens, a holographic optical element and a microlens array.

4. The polarization Raman spectroscopy system according to claim 3, wherein: The optical system is of high numerical aperture NA to allow the signal to be collected from multiple locations in a single measurement.

5. The polarization Raman spectroscopy system according to claim 4, wherein: The numerical aperture is adjustable to vary the size of the elongated linear spot on the sample.

6. The polarization Raman spectroscopy system according to any one of claims 2 to 5, wherein: The processor uses the 2D image of the line created by the 2-D image sensor to (i) retrieve Raman peaks from the 2D image of the line; (ii) generate a Raman amplitude distribution; (iii) determine the intensity of the Raman peak associated with a material; (iv) calculate a standard deviation from the Raman amplitude distribution of the Raman peak; and (v) calculate an average grain size therefrom.

7. The polarization Raman spectroscopy system according to claim 1, wherein: The polarized Raman spectrometer for generating the signals from small spots at the plurality of locations of the sample comprises: - a light source for generating the light beam, - a detection unit comprising a spectrometer, and -An optical system consisting of multiple lenses including an objective lens.

8. The polarization Raman spectroscopy system according to claim 7, wherein: The optical system is of high numerical aperture NA which results in the small spot size.

9. The polarization Raman spectroscopy system according to claim 8, wherein: The numerical aperture is adjustable to vary the size of the small-sized spot on the sample.

10. The polarization Raman spectroscopy system according to any one of claims 5 and 9, wherein: The numerical aperture can be adjusted via a variable aperture located at the back focal plane of the objective.

11. The polarization Raman spectroscopy system according to claim 1, wherein: The sample stage is translated along the XY axis for positioning the sample at the plurality of positions, thereby collecting the signals from the plurality of positions of the small spots.

12. The polarization Raman spectroscopy system according to claim 1, wherein: Scanning the light beam enables collection of the signal from small spots at the plurality of locations on the sample.

13. The polarization Raman spectroscopy system according to claim 7, wherein: The processor uses the signal detected via the detection unit to (i) retrieve a Raman peak from the 2D image of the line; (ii) generate a Raman amplitude distribution; (iii) determine the intensity of the Raman peak associated with the material; (iv) calculate a standard deviation from the Raman amplitude distribution of the Raman peak; and (v) calculate an average grain size therefrom.

14. A method of defining parameters of a polycrystalline material, the method comprising: (iv) providing a polarized Raman spectroscopy system according to any one of claims 1 to 13, (v) generating a plurality of signals from small spots at a plurality of locations on the sample or from elongated linear spots on the sample, and (vi) analyzing the plurality of signals to define the parameters of the polycrystalline material.

15. The method according to claim 14, wherein: Generating the signals from the small spots at the plurality of locations includes translating the sample stage along an XY axis of the stage to position the sample at the plurality of locations to collect the signals from the plurality of locations on the sample.

16. The method according to claim 14, wherein: Generating the signal from the small spots at the plurality of locations includes scanning a light beam to collect the signal from the plurality of locations on the sample.

17. The method according to claim 14, wherein: When the signal is generated from the elongated linear point on the sample, the method further comprises: (i) creating a 2D image of the line, (ii) retrieving a Raman peak from the 2D image of the line; (iii) generating a Raman amplitude distribution; (iii) determining the intensity of the Raman peak associated with the material; (iv) calculating a standard deviation from the Raman amplitude distribution of the Raman peak; and (v) calculating an average grain size therefrom.

18. The method according to claim 14, wherein: When the signal is generated from the small spots at the plurality of locations on the sample, the method further comprises: (i) detecting the signal, (ii) retrieving a Raman peak from the signal; (ii) generating a Raman amplitude distribution; (iii) determining an intensity of the Raman peak associated with a material; (iv) calculating a standard deviation based on the Raman amplitude distribution of the Raman peak; and (v) calculating an average grain size therefrom.

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