Snapshot ellipsometer

Abstract

SOLUTION: A snapshot ellipsometer or polarimeter does not require temporally modulated elements to measure a sample, but instead uses one or more spatially varying compensators 10, (e.g., microretarder arrays and compound prisms) to vary a polarization state within a measurement beam of electromagnetic radiation.EFFECT: Analysis of an intensity profile of a beam after interaction with spatially varying compensators and the sample allows sample parameters to be characterized without any moving optics.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an ellipsometer for measuring optical properties and physical parameters of a sample. More particularly, the present invention relates to a system for spatially varying the polarization state of a measurement beam. The present invention relates to a spectroscopic ellipsometer that characterizes a sample by subjecting the sample to a spectroscopic ellipsometer. [Background technology]

[0002] In traditional ellipsometry, electromagnetic radiation is The polarization state of the beam changes at least one parameter of the polarization state as a function of time. The light is modulated and / or analyzed by rotating the element. and linearly varying the azimuthal position of at least one optical element. Each rotating element is , which induces a time modulation in the signal intensity at a frequency related to the rotation rate of the optical system. The sign of the phase change (Δ) caused by the sample cannot be measured. A later refinement gave sensitivity to this parameter. Another type of ellipsometer uses a rotating compensator to apply stress to a photoelastic crystal. By applying a voltage to the piezoelectric transducer that induces, typically sinusoidally, A photoelastic modulator that changes the retardance of an optical system as a function of time. This stress induces a changing birefringence in the crystal, which in turn induces a retardation (shift In each of the above types of ellipsometers, the time The optical modulation is analyzed to determine the optical properties of the sample.

[0003] In general, elements such as rotating compensators and photoelastic modulators have some drawbacks. As a function of time, multiple measurement frames are required to fully describe the polarization state of the beam. Therefore, the measurement speed of the time-modulated ellipsometer is, in principle, The sample is limited by the hardware used in the coating process. For moving or rapidly changing objects, it is useful to complete measurements using stationary optics. Static element ellipsometers are also potentially cheaper than time-modulated systems. It can be constant, simple and compact.

[0004] To overcome the limitations of prior art ellipsometers, the temporal modulation of the detected beam Several designs have been proposed for systems that preclude the use of channeled ellipsometry. The detector and polarimeter provide information about the polarization state of the beam, as well as spectral information. or encoded onto the same dimension of the detector used for spatial information. In psometry, this is accomplished using a multi-order retarder. This has a length-dependent polarization effect, which results in higher Similarly, spatially channelized systems produce strong modulation patterns in the wedge. By imaging spatially varying optical systems such as wedged retarders, Thus, the intensity is modulated along one or both dimensions of the image plane. The system used is described in U.S. Pat. No. 5,399,323 by Oka et al. It has the potential to simultaneously capture a lot of information about the channel, polarization, and spatial components. The main drawback of a modularized system is that the information related to each variable must be separated. In most prior art techniques, this is done by Fourier transforming the intensity information obtained to obtain the individual modulations. This is achieved by extracting the characteristic frequencies of the source of the noise. include more complex signal processing, increased noise, and reduced resolution.

[0005] Snapshot ellipsometers and polarimeters have the disadvantages of channeled systems. Snapshot systems provide the benefits of stationary optics without the need for space. By imaging a time-varying optical element onto a dedicated dimension of a multi-element detector, If a two-dimensional detector is used, the other dimension is the sample or beam. It is used to capture information related to the spectral, angular, or spatial characteristics of a system. In the case of snapshot spectroscopic ellipsometry, the additional element is a beam splitter that orthogonally splits the electromagnetic radiation. Spectrally separated along the detector dimension, the beams in a single frame capture of the detector Allows for complete characterization of the polarization state and spectral profile of the Since the polarization modulation direction is independent, signal processing is simple and similar to traditional polarimetry techniques. is.

[0006] Mueller-Stokes calculations are performed using an ellipsometer. It is used to describe the change in polarization caused by each element in the optical train. The optical state is represented by a Stokes vector, whose elements describe the polarization effect of the optical system. It is described by the Euler matrix.

[0007] The Mueller-Stokes description for some common polarizing elements is given as can be obtained.

[0008] Unpolarized light is characterized by its intensity I and is described by the Stokes vector Stated:

[0009]

number

[0010] The following matrix converts the Stokes vector representing the polarized beam into a scalar representation of the intensity on the detector: Convert to now.

[0011]

number

[0012] A polarizer is a device for polarizing electromagnetic radiation having a polarization oriented along said axis. It is an element that has a characteristic pass axis that transmits only light.

[0013]

number

[0014] The analyzer is the part that follows the sample in an ellipsometry system. The Mueller matrix describing the analyzer is identical to that of the polarizer.

[0015]

number

[0016] A compensator is a component of a transverse electromagnetic wave that is This effect works by retarding the light emitted by the light beam. The retardance (d) is proportional to the difference in the refractive index of the birefringent crystal. Ordinary and normal refractive indices (n e , n0) and the thickness of the material through which electromagnetic radiation of wavelength (λ) propagates. When it is a function of (T), it is described by the following equation.

[0017]

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[0018] The Mueller matrix describing a general compensator is:

[0019]

number

[0020] For any element with a characteristic polarization axis, such as a polarizer or compensator, the rotation matrix is , is used to describe the azimuthal position (θ) of an element with respect to the plane of incidence.

[0021]

number

[0022] The most common mathematical description of a sample is the polarization of the beam induced by the sample. Mueller matrix with 16 elements that can completely describe any change in state It is.

[0023]

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[0024] In conventional ellipsometry, the polarization change induced by the sample is measured in two parameters: Although the polarization states are described by the parameters ψ and Δ, this notation can be used for partially polarized beams or depolarized samples. is insufficient to describe

[0025]

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[0026] To fully describe an isotropic sample and a partially polarized beam, we use an alternative notation: The isotropic quantities are related in the following way and substituted into the previous matrix as shown: Can be:

[0027]

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[0028]

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[0029] The N, C, and S notation is advantageous because it provides a simple relationship to the depolarization. Optical depolarization is defined as the conversion of fully polarized electromagnetic radiation into partially polarized electromagnetic radiation, and is The rule can be expressed as follows:

[0030]

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[0031] Depolarization is a function of surface electromagnetic radiation scattering, sample inhomogeneity, spectrometer bandwidth resolution, and non-parallel input beams. The incoherent sum of the electromagnetic radiation reflected from the back surface of the substrate and the angular spread from the beam is Depolarization measurements can be caused by a variety of factors, including It helps identify nonidealities in the

[0032] One of the most common elements used in prior art snapshot ellipsometers is the The retardation of the compensator is proportional to its thickness, so the spatial A birefringent optical system that varies in thickness over time will have different values ​​of retardance at different positions. The polarization state of the measurement beam changes as different parts of the measurement beam interact with different parts of the optical system. is spatially modulated.

[0033] The simplest example of such an optical system is a linear wedge made of a birefringent crystal. The thickness T of the wedge can be written as a function of the spatial position x along the direction of the displacement: Here, the rate of change is defined by the slope w of the wedge.

[0034]

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[0035] Substituting the thickness of the wedge into the general retardance equation, we obtain the retardance across the wedge The velocity can be described as a function of spatial position.

[0036]

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[0037] A new term D is defined to represent the rate of retardance change.

[0038]

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[0039] The Mueller matrix description of a wedge-shaped birefringent crystal is similar to that of a standard compensator, The spatial retardance is defined by d(x).

[0040]

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[0041] Any optical system that has birefringence and variable thickness can spatially change the polarization state of the beam incident on it. The term "wedge" is used herein to refer to such thickness variations. It can be used to describe any optical system where the thickness varies linearly or continuously, as in the example above. It is not specifically defined that the thickness profile of an optical system exhibits a discrete step-like thickness profile or a nonlinear The shape-changing optics can be easily substituted by one skilled in the art.

[0042] A common variation of the linear wedge retarder described above is the Babinet complement. The Babinet compensator is an assembly of two equal wedge-shaped crystals of uniaxially anisotropic material. The wedge is formed when the two wedge faces are in contact with each other or when they are in contact with each other, as shown in FIG. 3(B). are oriented with a small gap between them, parallel to each other and perpendicular to the incident beam. The optical axes of the two wedges are orthogonal to each other and to the beam.

[0043] The Mueller matrix describing the Babinet compensator is a two-component wedge with optical axes W1 and W2. It can be defined by matrix multiplication:

[0044]

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[0045] The slopes of the two wedges are equal and opposite, so the retardance ratio is For the first wedge it is defined as B and for the second wedge it is defined as -B.

[0046]

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[0047] This matrix represents a single wedge with twice the retardance change rate than its constituent wedges. matrix. Therefore, the Babinet compensator is equivalent to a single wedge with different slopes. Recognizing that the same polarization modulation is generated, we can now use the It will be apparent to those skilled in the art that the birefringent wedge can be replaced by a combination of wedges. The advantage of the Babinet compensator is that the retardance near the center of the optical system is zero order, and the The advantage of this is that it is less susceptible to polarization and separation when light passes through it. The term "rust" refers to the spatially varying retardance for a beam along one azimuth angle. Individual wedges and wedges such as Babinet compensators or optical wedges are used to affect the It is further understood to refer to both combinations of disciplines.

[0048] In US Pat. No. 5,399,633, Fluckiger et al. apply a spatially varying retardance to the beam. Fluckige describes an ellipsometer that uses a single wedge to provide The ellipsometer system described by R. was novel in its implementation but All sample parameters describing the anisotropic sample could not be detected. Fluckiger was severely limited in his ability to measure the The compensator was specified to be preferred over a single wedge.

[0049] Using the matrices defined above, the spatially varying signal strength of a single wedge system can be expressed by the following matrix multiplication:

[0050]

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[0051] The polarizer and analyzer must be placed in a non-unique polarization state of the wedge for each measurement. Assuming a sample of 0.1 mm in diameter and setting the azimuth angle of the polarizer and analyzer to 45°, the spatial variation of the beam intensity is The movement can be expressed as follows:

[0052]

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[0053] The Fourier transform of the signal along the axis of motion on the detector divides the equation into components occurring at different spatial frequencies Decompose into:

[0054]

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[0055] The real part of the Fourier coefficient (α k ) and the imaginary part (β k ) is a specific frequency related to the spatial variation of the compensator. It is nonzero at some number k. The Fourier transform of the theoretical intensity equation is a single harmonic frequency (k=2D ) and DC(k=0) terms. The theoretical Fourier coefficients are given by the sample parameters as follows: Data related to:

[0056]

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[0057] Solving for the sample parameters using the Fourier coefficients, the single wedge snare The snapshot ellipsometer can measure arbitrary It is clear that only two sample parameters can be measured in any single measurement. (X denotes insensitivity to the parameter).

[0058]

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[0059] Therefore, a single wedge system can measure three samples simultaneously. Since these are only two of the fundamental parameters, it is not possible to fully characterize isotropic samples. When measuring a sample with psi (ψ) close to 45° as arranged, the measurement Systematic errors and noise in the data are amplified. For a single wedge system, the entire polarization optics The configuration of all the parameters in ψ (Psi) and Δ (Delta) for a particular sample type is This results in an amplified error.

[0060] The U.S. patent to Oka et al. (Patent Document 1) and the U.S. patent to Fluckiger et al. In addition to the disclosure in U.S. Pat. No. 5,393,633, additional patents are identified. For convenience, all known prior art patents are listed and briefly discussed directly.

[0061] In US Pat. No. 5,399,633, Fluckiger et al. apply a spatially varying retardance to the beam. Fluckige describes an ellipsometer that uses a single wedge to provide The ellipsometer system described by R. was novel in its implementation but All sample parameters describing the anisotropic sample could not be detected. Fluckiger was preferred over a single wedge. A new Babinet compensator was specified.

[0062] Several inventions in the related field of polarimetry have been developed in ellipsometry. Polarimeters are devices that measure the distance between a beam of electromagnetic radiation and a target object. It is an instrument used to measure the polarization state, and sometimes the spectral characteristics, of light. In ellipsometry, by knowing the state of the beam before and after it interacts with the sample, By using the optical properties and physical structure of the sample, it is possible to determine the optical properties and physical structure of the sample. To determine information about the polarization state of a beam of electromagnetic radiation after it has interacted with a sample, However, polarimeters can be advantageously characterized as Ability to extract sample parameters directly from a source, polarization state generator, or measured polarization information It is not an ellipsometer in that it has no power. Polarimeters have traditionally been used While some of the more recent inventors have used stationary elements to analyze the beam, We have been seeking to create a polarimeter that can measure the wavelength of light.

[0063] The patent document 3 by Thoma et al. was used by Fluckiger in his ellipsometer. A single wedge polarimeter identical to that used in the study, but without the ability to measure spectroscopically, was identified. He also uses different holographic techniques to determine more information about the polarization state of the beam. We advocate using two wedges with different tilt directions. By applying the variable retardance independently to the two axes, the simplified data This allows for analysis but requires two dimensions on the detector for analysis.

[0064] Patent document 1 by Oka et al. describes an advanced imaging bar described by Thoma. The two wedges separate each retardance modulation onto a different axis of the detector. The retardance variation rate is similar to that of the many orders of modulation. The numbers are captured and the data can be determined independently at many points across both dimensions of the beam. High enough to

[0065] Sparks et al., US Pat. No. 4,399,433 also discloses the polarizing plate described by Fluckiger. The polarimeter is a point-and-shoot spectropolarimeter with an entrance slit. The patent also states that "the gradient of the retardance of the second optical system is different from that of the first optical system." To fully characterize the measurement beam, the requirement that the beams be of different angles and intensities is used. The patent describes the possibility of using two sets of wedges. The claims include a second set of wedges. is "either parallel or antiparallel to the first birefringent wedge, and "has twice the refractive index," i.e. the difference in the gradient strength is due to the different birefringence of the wedges. As mentioned above, Sparks' system is a wedge pair This is a spectroscopic polarimeter that requires an entrance slit right next to it.

[0066] In US Pat. No. 5,533,233 by Ansley et al., a polarizing filter is focused onto a detector that is stacked with three polarizing filters. The authors describe a polarimeter with an input slit that allows the polarizer to pass through the light source. Using only optical filters means that the device is unable to characterize the rotational direction for circularly polarized light. This means that it is not possible to

[0067] Abraham et al., US Pat. No. 6,363,313, uses spacing smaller than the wavelength of the electromagnetic radiation used. A particular type of spatially varying retarder array consisting of a deposited dielectric grid structure having This optical system does not rely on the birefringence of the material, but on the polarimeter. The retardance is generated by the interaction of the beam with the grid structure of the element. is used in polarimetry to determine the polarization state of a beam. Abraham also He also describes two specific applications of his polarimeter: first, as a reflection type electromagnetic radiation microscope; The application is to form an imaging ellipsometer with mirrors. In this application, optics and polarizing films Second, a more traditional ellipsometer with a laser light source is used. It is Tar.

[0068] No. 6,399,323 by Alonso et al. is a hologram obtained by scanning a sample from a light source placed vertically above the sample. The present invention describes a focused beam scattering device that provides a focused beam onto a sample to be measured. The system is equipped with a beam splitter and a focusing lens in front of the investigated sample, so that the focused beam The light exhibits a spatially varying polarization state. No elements are present on the detector side. The beam is incident on the sample with a trajectory perpendicular to the incident beam path. It is reflected back along the

[0069] US Pat. No. 5,399,363 to Lee is a patent application published by Fluckiger and Abraham. Lee describes the progress made toward a polarizing beam splitter. and a retroreflective path design with a concave mirror to make the unit more compact. [Prior art documents] [Patent documents]

[0070] [Patent Document 1] U.S. Patent No. 7,336,360 [Patent Document 2] U.S. Patent No. 6,052,188 [Patent Document 3] U.S. Patent No. 6,850,326 [Patent Document 4] U.S. Patent No. 9,097,585 [Patent Document 5] U.S. Patent No. 7,038,776 [Patent Document 6] U.S. Patent No. 6,275,291 [Patent Document 7] U.S. Pat. No. 9,793,178 [Patent Document 8] U.S. Pat. No. 7,489,399 Summary of the Invention [Problem to be solved by the invention]

[0071] Considering the known prior art, in the field of ellipsometry and polarimetry, Progress in this area remains needed. [Means for solving the problem]

[0072] The present invention comprises, in part, a) a source of an electromagnetic radiation beam (2); b) a polarization state generator (4); c) A collimated or uncollimated electromagnetic radiation beam (3) is sampled at a known angle of incidence. Facilities for interacting with the pull (5), d) a polarization state analyzer (6), and e) Multi-element detector of electromagnetic radiation (8) The ellipsometer includes:

[0073] In use, an electromagnetic radiation beam (3) is generated by said electromagnetic radiation beam source (2), The polarization state generator (4), the sample (5), the polarization state analyzer (6), and the polynomial The polarization state generator (4) and / or the polarization state detector (8) are caused to interact with each other. The phase analyzer (6) further comprises at least one of the following spatially varying compensators (10): Includes: Two or more birefringent optical systems with mutually oblique crystal axes and spatial thickness variations (16 ), and An array of unstructured retarding elements (14) on the order of the measured wavelength. I (13).

[0074] The spatially varying compensator (10) provides a plurality of spatially separated polarization states. As a result, the spatial distribution of intensity over the cross-sectional area of ​​the beam is known as polarization state analysis. After interacting with the detector (6), corresponding positions are detected in the detector (8). The sample is detected by multiple spatially distributed elements that are analyzed to determine the sample characteristics. It is possible.

[0075] The ellipsometer detects a particular point on the spatially varying compensator (10) and the detector (14). (8) To improve the resolution of correspondences between particular points on the spatially varying At least one imaging element is present between the compensator (10) and the multi-element detector (8). The sensor may further include:

[0076] The ellipsometer is configured such that the beam provided by the electromagnetic radiation beam source (2) is a plurality of The detector (8) may be two-dimensional and may include wavelengths, and the ellipsometer may be The detector further comprises at least one wavelength separation element (7) in front of the detector (8), 2. Determine the polarization effect of the sample for multiple wavelengths at each location of the sample being investigated The at least one wavelength separation element (7) may be selected from the group consisting of: You can: Planar or curved diffraction gratings; Dispersing prism; and Attenuating or reflective filter elements that transmit, block, or reflect different wavelengths at different positions .

[0077] Furthermore, the ellipsometer includes at least one additional imaging optical system (12) for imaging the wave. The spectral variations caused by the long separation element (7) are detected in one dimension of the detector (8). It is possible to decompose it into:

[0078] The ellipsometer is characterized in that the electromagnetic radiation beam source (2) is selected from the group consisting of: It can be done like this: Broadband or monochromatic lasers; Broadband or narrowband LEDs; Monochromator; broadband sources; FTIR source; Glover Source; incandescent light sources; and Arc lamp.

[0079] The ellipsometer uses a combination of multiple sources (2) of electromagnetic radiation beams to A broader or more favorable spectrum may be provided.

[0080] The ellipsometer may further include a beam splitting element to improve data quality. or to provide an image of the beam profile or sample surface. The intensity profiles of both beams are detected.

[0081] The ellipsometer comprises a spatially varying compensator (10) and a polarization state generator (4). The spatial modulation of the two elements is performed by the imaging optics and / or the low-pass filter. Divergent illumination can be used to cause the images to be optically overlapped in a known relationship.

[0082] The ellipsometer includes a spatially varying compensator (10) and a magnifying optics. Different effective illumination can be achieved on the detector through changes in compensator characteristics and / or through convergent or expanded illumination. A modulation frequency can be provided.

[0083] The ellipsometer is a polarization state generator (4) and a polarization state analyzer (6) that are effective spatially variable. The harmonic frequencies are in the ratios 1:3, 3:1, 1:5, 5:1, 3:5, or 5:3. It is possible.

[0084] The ellipsometer is adapted to measure the angle of incidence of the electromagnetic radiation beam on the surface of the sample (5). The optical system of the ellipsometer is adjusted through a mechanism that moves a part or all of the optical system of the ellipsometer relative to the sample. It is possible to make the size of the slit 11 adjustable.

[0085] The ellipsometer is configured such that the electromagnetic radiation beam source (2) is a monochromator, an optical fiber, or The output from the pinhole is adjusted so that the beam has desired spectral or spatial characteristics. It can be done.

[0086] The ellipsometer detects the electromagnetic radiation beam provided by the electromagnetic radiation beam source (2). The camera approaches the sample surface along a trajectory that is perpendicular or substantially perpendicular to the sample surface. You can make sure that doesn't happen.

[0087] The ellipsometer is characterized by at least one selection from the group consisting of: You can: the light source does not comprise one or more lasers; and There is no serial combination of a slit and a wedge-shaped compensation element between the light source and the sample. Does not exist.

[0088] The method of characterizing a sample comprises the following steps: a) providing an ellipsometer as described above; b) by said detector (8) in response to a beam of electromagnetic radiation being input to said detector (8). Access the data provided by c) analyzing said data to characterize said sample (5).

[0089] The present invention alternatively comprises: a) a source of a beam of electromagnetic radiation (2); b) Polarization state generator (4); c) Provision for interacting a sample with said beam at a known angle of incidence; d) a polarization state analyzer (6); and e) Multi-element detector of electromagnetic radiation (8) The ellipsometers listed include:

[0090] The ellipsometer includes both the polarization state generator (4) and the polarization state analyzer (6). At least one element having a plurality of positions (13)(14) or each of which has at least A plurality of elements having a position (16), or a combination thereof, Each of the beam cross sections is a cross-sectional view of how the portion of the beam cross section interacts with at least one of the positions therein. The polarization characteristics of the beam are dependent on the type of light used.

[0091] In use, the electromagnetic radiation beam generated by the electromagnetic radiation beam source (2) is A light state generator (4), the sample (5), and the polarization state analyzer (6) interact with each other. As a result, the spatial intensity distribution across the cross section of the beam and the The corresponding positions are detected substantially simultaneously by the multi-element detector (8). from which the intensity profile can be calculated to characterize the properties of the sample (5) by measuring the polarization state It can be analysed using knowledge of the characteristics of the generator (4) and the polarization state analyser (6).

[0092] The method of characterizing a sample comprises the following steps: a) providing an ellipsometer as described above; b) by said detector (8) in response to a beam of electromagnetic radiation being input to said detector (8). Access the data provided by c) analyzing said data to characterize said sample (5).

[0093] The present invention is also a spectroscopic polarimeter comprising: a) Equipment for capturing a beam of electromagnetic radiation; b) Polarization state analyzer (4); c) a wavelength separation element (7); and c) Multi-element detector of electromagnetic radiation (8) Equipped with.

[0094] In use, the captured electromagnetic radiation beam enters the spectro-polarimeter, which polarizes the beam. It is interacted with a spectrometer (6), a wavelength separation element, and the multi-element detector (8).

[0095] The polarization state analyzer (6) comprises at least one of the following spatially varying compensators (10): and A combination of two or more birefringent optical systems with mutually oblique crystal axes and spatial thickness variations and an array of unstructured retarding elements on the order of the wavelength to be measured; Its function is to intensify the cross section of the beam by interaction with a polarization state analyzer (6). The aim of this study is to provide multiple polarization states which result in a spatial distribution of polarization degrees.

[0096] In use, the intensity is detected by corresponding elements of the detector (8) at multiple points within the distribution. The light is detected at a number of positions and analyzed to determine the polarization state of the beam for a range of wavelengths. can be.

[0097] The method of characterizing the polarization state of a beam of electromagnetic radiation then comprises: a) providing a system as just described; b) accessing a beam of electromagnetic radiation such that data is generated by said detector (8); death; c) by the detector (8) in response to a beam of accessed electromagnetic radiation being incident on the detector. Access the data provided by the d) analyzing the data to characterize the beam. Includes steps.

[0098] The present invention is better understood by reference to the detailed description herein in conjunction with the drawings, in which: It will be understood.

[0099] The objective of the present invention is to obtain a solution with complete sensitivity to the sample parameters ψ and Δ in any range of values. ,Snapshots that can characterize a sample in a single frame capture To this end, a spatially varying polarization A novel arrangement of optical elements was developed. Prior art ellipsometers use a wedge birefringent crystal and A Babinet compensator was used to spatially modulate the polarization state of the measurement beam. This allows for snapshot measurements but does not allow for complete characterization of the sample. A novel feature of the present invention is the use of obliquely oriented collimators to spatially modulate the polarization state of the measurement beam. The solution is to use two such wedges with crystal axes.

[0100] Another novel feature of the present invention is the use of multiple couplings that exist to provide the required spatial modulation. The first approach is to use an array of liquid crystal retarding elements having a crystalline orientation.

[0101] Another novel feature of the present invention is the spatially varying polarization both before and after interaction with the sample. The measurement beam interacting with the optical element provides additional information about the sample. Some spatially varying polarizing elements, such as variable azimuth retarder arrays on each side of the sample, A few combinations even make it possible to measure the complete Mueller matrix that characterizes the sample. To perform. [Brief description of the drawings]

[0102] [Figure 1] 1(A) and 1(B) show front and top views, respectively, of an embodiment of the present invention. [Diagram 2] 1 shows a retarder array designed with compensator azimuthal positions that vary linearly across the array, with the fast axis direction at each position indicated by a line across the face of the subelement. [Diagram 3] FIG. 3(A) shows a single birefringent wedge. The fast axis is indicated by a line across the face of the wedge. FIG. 3(B) shows a Babinet compensator that is mathematically equivalent to a single wedge, but provides a lower order retardance. FIG. 3(C) shows a double Babinet compensator. FIG. 3(D) shows a wedge pair with crystal axes oriented at an angle to each other. FIG. 3(E) shows a novel compound prism that provides full sample sensitivity and is also a low order retarder. The fast axis direction of each birefringent element is indicated by a line across the face of the optical system. [Figure 4]4(A) and 4(B) show front and side views, respectively, of an ellipsometer system implementing a spatially varying compensator (10) on the light source (2) and detector (8) sides, as well as additional imaging optics (12) used to reduce the size of the beam on the sample (5) and to image the spatially varying compensator (10) onto the detector (8). [Diagram 5] It is a simple ellipsometer that has a spatially varying compensator (10) in both the polarization state generator (4) and the polarization state analyzer (6), and does not require imaging optics to achieve the magnification and resolution of the spatially varying compensator (10). [Figure 6] 1 is an alternative embodiment configured to measure a sample (5) in transmission mode rather than reflection mode. [Figure 7] 1A-1D are front and alternative (unfolded top view) views of a polarimeter of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0103] Referring to the drawings, a preferred embodiment of the ellipsometer (1) of the present invention is shown in FIG. The preferred embodiment includes a light source (2) generating a beam of electromagnetic radiation (3). The electromagnetic radiation beam (3) is coupled to a polarization state generator (4) that includes at least a single polarizer (9). The beam then interacts with the sample (5) to produce a known polarization state. The beam has a spatial distribution of intensity along one dimension. The beam is then spatially-varying. The polarization state analyzer (6) consists of a polarizer (10) and an analyzer (11). The polarizer and the polarizer are the same type of element, and in the ellipsometer, they are located on the light source side of the sample and on the polarizer side of the sample, respectively. (The wavelength-dispersing prism or diffraction grating is used for the wavelength-dispersing prism.) The isolating element (7) serves to separate the individual wavelengths along the orthogonal dimension. 8) captures a portion of the wavelength-dependent intensity profile in a single frame. Knowledge of the polarization effects of the detector (4) and the polarization state analyzer (6) allows the determination of the intensity profile of a beam of electromagnetic radiation. Allows calculation of wavelength-dependent sample parameters based on a file. Steering the beam and There is additional imaging optics (12) that provides the necessary dimension of resolution. The linear variation of the compensator (10) is imaged in one dimension onto the detector (8), while the wavelength separation element The spectral separation caused by (7) is imaged onto the orthogonal dimension. The resolution is dominated by the beam divergence and does not require an additional slit on the detector side.

[0104] The patent describes two types of spatially-localized ellipsometers for use in snapshot ellipsometers. We disclose the application of a variable compensator (10), both of which fully characterize isotropic samples. In order to achieve this, the spatially varying compensator (10) provides an appropriate modulation of the polarization state of the beam. ) is as follows: a) A combination of two or more wedge-shaped birefringent optical systems (16) having mutually oblique crystal axes. and; b) Unstructured retarding elements on the order of the wavelength present in the measurement beam Array of (13)(14).

[0105] Referring to FIG. 2, a diagram of the microretarder array (13) is shown with individual compensator elements (14). The fast axis azimuth of each retarder element is shown in the horizontal dimension θ=Ca It is shown to vary linearly along z[x], while there is no vertical variation. The turn allows for simplified data extraction along the horizontal dimension and This makes it possible to separate wavelengths in the

[0106] The Mueller-Stokes formalism mathematically describes the disclosed retarder array (13). Can be used to:

[0107]

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[0108] Using the Mueller-Stokes formalism, the ellipsometer (1) detector (8) The theoretical signal intensity can be expressed as a function of spatial position x:

[0109]

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[0110] Variable azimuth angle, polarizer azimuth angle set at 45° and analyzer azimuth angle set at 0° Assuming a quarter-wave retarder array with Given the formula:

[0111]

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[0112] The spatially varying intensity for the retarder array described above corresponds to the temporal It is clear that the Fourier transform of the signal gives the equation for different spatial frequencies: The resulting components are decomposed as follows:

[0113]

number

[0114] Fourier coefficients (α k , β k ) at a certain frequency k, which is related to the geometry of the optical system The Fourier transform of the theoretical intensity formula gives the value of twice the spatial frequency of the compensator fluctuation. The harmonic frequencies were identified at four times.

[0115] The 2ω and 4ω harmonics are measured in one measurement, with three sample parameters (N, C, and S) The variable ω is now in units of rad / mm instead of rad / s. The theoretical Fourier coefficients are related to the sample parameters as follows:

[0116]

number

[0117]

number

[0118] Therefore, the theoretical relationship between the Fourier coefficients and the sample parameters is the same as for the rotating compensator device. This is the general case when a polarizer or analyzer position is used. The main requirement for this is that the retardance of the retarder array is constant across all pixels. This is what we should do.

[0119] Referring to Figures 3(A)-3(F), it can be used as a spatially varying compensator. Several birefringent wedges and compound prisms are shown that can be used for the Although shown separately, they can be attached together for optimal performance. A single birefringent wedge (15) is shown, which provides the spatial variation of retardance. The fast axis of the element is shown as a line on the plane of the optical system. 16) is shown. This compensator is shown in two birefringent This combination provides low order retardance and reduced beam deviation. FIG. 3(C) shows a combination of two Babinet compensators (16) with different crystal orientations. Because the wedges are aligned, the retardance changes only along the vertical direction. Although the combination of fast axes of provides additional information about the sample, four separate wedges It is difficult in practice to align the wedge inclinations for the two Babinet compensators. and allows for data extraction at a single spatial frequency, or they can be different, This allows the modulation of the wedge to be extracted at separate spatial frequencies. The optical system shown in FIG. 1 shows a pair of birefringent wedges (17) with their crystal axes intersecting (neither intersecting nor parallel). This optical combination provides the beam modulation required for fully isotropic sample characterization. Although new for use in ellipsometry, it exhibits multi-order retardance. Parallel retardance plates (18) consisting of FIG. 1 illustrates a novel advancement to the aforementioned optical system in which each plate retarder is a wedge. For each wedge plate pair, the two plates have orthogonal optical axes and similar retardances. The effective retardance is low. In addition, the use of only one wedge pair reduces the beam deviation. This results in a smaller number of steps and simplifies alignment. One can conceptualize many compound wedges that serve the same purpose. The use of at least two birefringent crystals with fast axes and thickness variations provides a perfect sample. This is a novel aspect that allows for pull characterization.

[0120] In the optical system shown in Fig. 3(C), (D) and (E), each wedge (W1, W2 The theoretical signal intensity of an ellipsometer (1) having a crystal axis orientation of can be expressed as:

[0121]

number

[0122] The polarizer and analyzer are not oriented to the eigenpolarization state of the wedge for each measurement. pull, 45° polarizer azimuth, 0° fast axis for the first wedge, For the 90° fast axis, 0° analyzer azimuth, and equal magnitude for both wedges, , assuming opposite retardance variation rates, the theoretical signal strength takes the form:

[0123]

number

[0124] The Fourier transform of a signal decomposes the expression into components occurring at different spatial frequencies.

[0125]

number

[0126] Fourier coefficients (α k , β k ) is a certain spatial frequency k related to the orientation and spatial variation of the compensator. is not zero. The Fourier transform of the theoretical intensity equation gives the retardance fluctuation rate of the wedge and the DC Identify the harmonic frequencies associated with the terms. Each frequency component has a real and an imaginary component. The theoretical Fourier coefficients are related to the sample parameters as follows:

[0127]

number

[0128] Use theoretical expressions for the Fourier coefficients to solve for the sample parameters and two spatially varying The snapshot ellipsometer, which consists of three elements, captures three samples in any single measurement. It is clear that the parameter X can be measured. It shows insensitivity to

[0129]

number

[0130] Therefore, the spatially varying retarder array or double wedge compensator described The snapshot ellipsometer is sensitive to at least three sample parameters: , ψ and Δ can be measured over any range of values.

[0131] In addition to the general layout described above, there are several other options to improve the functionality of the system: Variations of the preferred embodiment are possible, many of which are shown in Figures 4(A) and 4(B). It is being done.

[0132] A beam of electromagnetic radiation incident on a sample is made to have a smaller cross-sectional area at the sample. This correction can be achieved by focusing the sample with additional imaging optics. Reduce the impact of misalignment and non-uniformity on data quality.

[0133] Both the polarization state generator (4) and the polarization state analyzer (6) are provided with a spatially varying compensator (10 ) can be used to measure the complete Mueller matrix that describes the sample. Each spatially varying compensator (10) produces a different spatial frequency at the detector (8). In this case, parameters can be extracted at each of the component frequencies as well as the sum and difference of these frequencies. This can be achieved by using two SVCs with different spatial frequencies, can be achieved by magnifying each differently onto the detector.

[0134] The intensity profile produced on the detector (8) is a function of the spatial distribution of the spatially varying compensator (10). Since the two components are affected by temporal changes, it is important to achieve adequate resolution between them. Referring to Figures 4(A) and 4(B), the spatially varying compensator (10) Additional imaging is performed to ensure that the image planes overlap each other and enter the detector (8). The optical system (12) is shown and used. In FIG. 4(A) and FIG. 4(B), the sample (5) Additional imaging optics (12) near the sample (5) are used to focus the beam onto the sample (5), The spatially varying compensator (10) is imaged after interacting with the sample (5). If the compensator (10) which varies in a time course has only one-dimensional variation, the variation axis is displayed on the detector (8). It is only necessary to image the A slit can be used, but this is done by placing a slit at the entrance of the detector. This is done instead of using a cylindrical optical system and a wavelength separation element after the polarization state analyzer (6). A spherical optical system behind the compensator (7) transmits the spatially varying fluctuations of the compensator (10) to a detector (8). It serves to image the wavelength separation in the orthogonal dimension.

[0135] In a system including two spatially varying compensators (10), adequate resolution and The simplest way to ensure the correct magnification is shown in Figure 5. The beam used in this example is The fiber acts as a point source, such as the output of a fiber optic or pinhole. The fiber homogenizes the beam. This can serve to provide layout flexibility. Point light sources capture spatially varying light without the use of additional optics, similar to the function of a pinhole camera. The compensation element (10) ensures that both beams are properly resolved on the detector (8). The expanding nature of the θ function serves to expand the spatially varying compensators (10) relative to each other. As a result, each spatially varying compensator (1) has a different spatial frequency on the detector (8). 0) modulation, making it possible to separate the signals.

[0136] The system layout in Figure 6 is the same as that in Figure 1, but the sample is now reflected. Instead, it is measured in transmission, which may be advantageous for certain samples.

[0137] The layout shown in FIG. 7(A) and FIG. 7(B) is, as mentioned above, a polarization state analyzer (6) , a wavelength separation element (7), and a detector (8) for use in measuring an electromagnetic radiation beam. The polarization state analyzer (6) is a spectroscopic polarimeter that can be used to measure the spatially varying and an analyzer (11) that fully characterizes the polarization information of the beam. The wavelength separation element (7) allows characterization of the complete polarization state for multiple wavelengths of light. The additional imaging optics is a spatially varying compensator (10) with a varying axis and a detector (8). The wavelength separation element (7) is shown as a curved diffraction grating, No additional optics are required to resolve the spectral information of the beam. It is filtered or homogenized using holes, slits, and optical fibers, and is As with the Larymeter, data accuracy can be guaranteed.

[0138] The electromagnetic radiation beam source (2) may, unless excluded by the wording of the claims, consist of: can be selected from the group consisting of: laser; LED; broadband sources; FTIR source; Glover Source; incandescent light sources; and Arc lamp.

[0139] Furthermore, it functions as a single source of a beam of electromagnetic radiation (2) having more favorable spectral characteristics. To achieve this, multiple electromagnetic radiation sources can be used and their optical signals combined. For example, the electromagnetic radiation from some LEDs and lasers can be used to produce a broadband beam. Using hot / cold mirrors, beam splitters, branching optical fibers, or other methods It is possible to collimate the light.

[0140] The electromagnetic radiation beam source (2) is the output of a monochromator that provides only one optical wavelength. The electromagnetic radiation beam source (2) acts as a point source and has a Alternatively, it may be provided as the output of an optical fiber or pinhole through which the electromagnetic radiation is transmitted. .

[0141] The spatially varying compensator (10) may be any of the following, unless excluded by claim language: You can choose from the group consisting of: An array of retarder elements (14) that are not structured on the scale of existing optical wavelengths (1 3) A combination of the above, and At least two birefringent wedges (16) having crystal axes oriented obliquely to each other.

[0142] In a preferred embodiment, the modulation produced by the spatially varying compensator (10) is dimensional only, and the light source (2) used also provides a beam with multiple light wavelengths present. Wavelength separation elements such as dispersive prisms and diffraction gratings (e.g., (7)) produce a two-dimensional It is used to separate the individual wavelengths along the other dimension of the detector (8). This allows the pull parameters to be determined independently for each wavelength.

[0143] The wavelength separation element (7) may be present in the beam unless excluded by the wording of the claims. The optical fiber may be any element or combination of elements that allows for the separation or selection of different wavelengths. The wavelength separation element can be flat or curved diffraction gratings; Dispersing prism; and Filter elements that transmit, attenuate, or reflect different wavelengths at different positions Includes.

[0144] The retarder array may be configured to spatially vary the retardance and / or fast axis orientation in a sequential or non-sequential manner. This preferred embodiment can be designed to vary the optical design or data. The retarder array is a retarder array in which the azimuthal orientation of each compensator element is sequentially changed through one of two input and output operations. This approach is mathematically similar to the rotating compensator ellipsometer, but , the azimuth rotation matrix has a spatial dependence, not a time dependence. In the case of an array, as long as there is a suitable azimuthal angle or retardance to characterize the sample, , the individual elements or zones can be in any pattern. and if the retardance is constant, the Fourier analysis above is used to extract the data. For other patterns or values ​​of elements, alternative analysis methods may be used. can.

[0145] Prior art techniques have used single wedge systems and patterned dielectric grid retarders to However, the present invention discloses analyzing a beam of electromagnetic radiation after interaction with a sample, which is not a polarization state generator. For any type of spatially varying polarizing element in the vessel (4), some of the space therein Probing a sample with a beam of electromagnetic radiation having multiple polarization states present at a target position. is a novel approach in ellipsometry.

[0146] Also, to be able to fully characterize anisotropic samples, a polarization state generator (6) At the same time, the polarization state generator analyzes the polarization state present in the spatially varying polarization element in the (4) Any type of spatially varying polarization component in the Probing a sample with a beam of electromagnetic radiation having multiple polarization states present at intermediate positions In order to achieve this, a spatially varying The use of polarizing elements is also novel.

[0147] For clarity and brevity, the illustrated systems are generally described as using refractive optics. Although shown and described, those skilled in the art will recognize that refractive optics, reflective optics, and diffractive optics are all It should be appreciated that other elements may be used to achieve the same functions as those described. Additionally, although the measurement beam is shown interacting with the sample in reflection, Electromagnetic radiation transmitted through the sample may also enable characterization of the sample.

[0148] The Fourier transform is also used as a signal processing technique to extract sample parameters. It should also be noted that the above is described in terms of the intensity profile. The reader will be aware of other signal processing techniques that allow for the extraction of sample parameters.

[0149] The beam propagation direction can be defined for any beam, even if it is collimated. Note that the optical fiber may or may not be focused. Although it is not critical to the invention as to how this is actually accomplished in any particular case, The term "beam" for purposes of this disclosure refers to a propagating method of electromagnetic radiation having a finite cross-sectional area. It should be understood that the cross section of the beam is characterized by the direction of the beam. It allows you to distinguish different positions within it, each of which is the same as a separate beam. That is, the present invention refers to any convenient two-dimensional measurement of the distance between a beam of electromagnetic radiation and other similar " Independent" beams are affected differently, virtually regardless of how they are effectively affected. We consider this to be a valid combination of many individual "separate" beams that can be used.

[0150] The terms "cylindrical" and "spherical" are sometimes used to refer to imaging elements such as curved mirrors and lenses. Note that these terms are used to describe the exact shape of the optical surface. Instead, the optic is used to measure curvature in only one dimension, as a section of a cylinder. or as part of a sphere, has both dimensions Only used for this purpose. It is understood that other parts of parabolic, elliptical, and aspherical geometric shapes are also included. will be done.

[0151] The recited negative limitations may be incorporated into the claims to avoid reference to prior art. However, if a negative limitation is not included in the claim, the absence of said element is equivalent to the absence of said element. does not indicate that an element is not present in the system of the present invention at at least one position in The claims are based on the premise that "they include."

[0152] Also, although not relied upon to provide novelty, various elements referred to in this application may be illustrated in the drawings. Note that the optical elements are not specifically presented. Examples include wavelength filters, beam splitters, etc. , a slit and an optical fiber as part of the beam source of electromagnetic radiation, a cylindrical optical system, and a detector Beam resolution applied to spherical optics, plane gratings, and lasers, LEDs, broadband, FTI There are various light source types, such as R, globar, incandescent arc lamp, etc. Such elements are well known in the art. The JAW This can be found and described in patents issued to Oellm Co., Inc. Currently, approximately There are 95 such patents, all of which are incorporated herein by reference. Persons reserve the right to incorporate content from identified patents.

[0153] Although the subject matter of the present invention has been disclosed herein, many modifications, substitutions, and variations of the present invention are possible in accordance with the teachings. It will be apparent that the present invention is thus possible in light of the The present invention may be practiced other than as disclosed herein and should be limited in breadth and scope only by the claims. Please understand that this is necessary.

Claims

1. a) a source of an electromagnetic radiation beam (2); b) a polarization state generator (4); c) equipment for interacting a collimated or non-collimated beam of electromagnetic radiation (3) with a sample (5) at a known angle of incidence; d) a polarization state analyzer (6), and e) Multi-element detector of electromagnetic radiation (8) Equipped with In use, an electromagnetic radiation beam (3) is generated by the electromagnetic radiation beam source (2) and is caused to interact with the polarization state generator (4), the sample (5), the polarization state analyzer (6) and the multi-element detector (8); the polarization state generator (4) and / or the polarization state analyzer (6) further comprise a liquid crystal phase shifting element (13)(14) not arranged on the order of the measurement wavelength, a spatially varying compensator (10) being a phase shifting element with a spatial array having at least two mutually rotating, independent optical axes but a plurality of zones exhibiting the same phase shift, the at least one spatially varying compensator (10) imparts a plurality of spatially separated polarization states resulting in an intensity distribution across a cross section of the beam which, after interaction with the polarization state analyzer (6), is detected at a plurality of corresponding positions by a corresponding plurality of spatially distributed elements in the detector (8); The sample is analyzed to determine characteristics Ellipsometer.

2. and at least one imaging element between the spatially varying compensator (10) and the multi-element detector (8) for improving resolution with respect to a correspondence between the spatially varying compensator (10) and a particular point on the detector (8).

10. The ellipsometer of claim 1.

3. The beam provided by the electromagnetic radiation beam source (2) comprises a plurality of wavelengths, and the detection the detector (8) is two-dimensional and the ellipsometer further comprises at least one wavelength separation element (7) in front of the detector (8), such that, in use, the polarization effect of the sample is determined for a plurality of wavelengths at each position of the sample being investigated.

10. The ellipsometer of claim 1.

4. At least one wavelength separation element (7) is selected from the group consisting of:

4. The ellipsometer of claim 3, Planar or curved diffraction gratings, A dispersing prism, and An attenuating or reflective filter element that transmits, blocks or reflects different wavelengths at its different positions.

5. at least one additional focusing optic resolves the spectral variations caused by the wavelength separation element (7) onto one dimension of the detector (8), the at least one focusing optic being between an analyzer (11) and the multi-element detector (8); 4. The ellipsometer of claim 3.

6. 2. The ellipsometer of claim 1, wherein the electromagnetic radiation beam source (2) is selected from the group consisting of: Broadband or monochromatic lasers; broadband or narrowband LEDs; Monochromator; Broadband light source; FTIR light source; Globar light source; Incandescent light source; and Arc lamp.

7. Multiple sources of electromagnetic radiation beam (2) are used in combination to extend the wavelength range or to provide a more uniform intensity profile across the measured electromagnetic spectrum.

10. The ellipsometer of claim 1.

8. further comprising a beam splitting element, and the resulting intensity profiles of both beams are detected to improve data quality or to provide an image of the beam profile or sample surface.

10. The ellipsometer of claim 1.

9. A spatially varying compensator (10) is present in both the polarization state generator (4) and the polarization state analyzer (6), and the spatial modulation of the two compensators is achieved using imaging optics and / or low divergence illumination. , which are optically superimposed in a known relationship using 10. The ellipsometer of claim 1.

10. The spatially varying compensator imparts different effective modulation frequencies to the detector via magnifying optics, spatially varying changes in compensator properties, and / or focused or magnified illumination. 、 10. The ellipsometer of claim 9.

11. 11. The method according to claim 10, wherein the effective spatial modulation frequencies of the polarization state analyzer and the polarization state generator are imaged onto the detector (8) in a ratio of 1:3, 3:1, 1:5, 5:1, 3:5 or 5:

3. The ellipsometer described.

12. The angle of incidence of the electromagnetic radiation beam on the surface of the sample is adjustable.

10. The ellipsometer of claim 1.

13. The source of electromagnetic radiation beam (2) is the output of a monochromator, an optical fiber, or a pinhole, so that the beam has desired spectral or spatial characteristics; 10. The ellipsometer of claim 1.

14. the electromagnetic radiation beam provided by the electromagnetic radiation beam source (2) does not approach the sample surface along a trajectory that is perpendicular or substantially perpendicular to the sample surface; 10. The ellipsometer of claim 1.

15. Characterized by at least one selection from the group consisting of:

10. The ellipsometer of claim 1 , the light source does not include one or more lasers; and There is no in-line combination of a slit and a wedge-shaped compensation element between the light source and the sample.

16. a) a source of an electromagnetic radiation beam (2); b) a polarization state generator (4); c) Provision for interacting a sample with said beam at a known angle of incidence; d) a polarization state analyzer (6), and e) Multi-element detector of electromagnetic radiation (8) Equipped with both the polarization state generator (4) and the polarization state analyzer (6) comprise at least one liquid crystal element having a plurality of azimuthal positions (13)(14), each of said elements acting to provide a beam polarization characteristic that depends on how a portion of said beam cross-sectional area interacts with at least one of said element positions; In use, an electromagnetic radiation beam generated by the electromagnetic radiation beam source (2) is caused to interact with the polarization state generator (4), the sample (5) and the polarization state analyzer (6), thereby generating a spatial intensity distribution across a cross-section of the beam, and corresponding positions in the beam cross-section are detected substantially simultaneously by the multi-element detector (8); In use, the spatial intensity distribution is analyzed using the properties of a polarization state generator (4) and a polarization state analyzer (6) in order to characterize the properties of the sample (5). Ellipsometer.

17. a) equipment for capturing the beam; b) a polarization state analyzer (4); c) a wavelength separation element (7), and d) Multi-element detector of electromagnetic radiation (8) A spectral polarimeter comprising: The polarization state analyzer (6) comprises at least one spatially varying compensator (10) of the polarization state generator (4) and / or the polarization state analyzer (6) further comprises a liquid crystal phase shifting element (13)(14) not arranged on the order of the measurement wavelength, a spatially varying compensator (10) being a phase shifting element with a spatial array having at least two mutually rotating, independent optical axes but a plurality of zones exhibiting the same phase shift, In use, the spectral polarimeter detects intensity at multiple locations of the distribution by corresponding elements of the detector (8) and analyzes to determine the polarization state of the beam for a range of wavelengths. Spectral polarimeter.

18. a) a') a source of an electromagnetic radiation beam (2); b') Polarization state generator (4); c') equipment for interacting a collimated or focused electromagnetic radiation beam (3) with a sample (5) at a known angle of incidence; d') a polarization state analyzer (6), and e') Multi-element detector of electromagnetic radiation (8) Equipped with In use, an electromagnetic radiation beam (3) is generated by the electromagnetic radiation beam source (2) and is caused to interact with the polarization state generator (4), the sample (5), the polarization state analyzer (6), and the multi-element detector (8); The polarization state generator (4) and / or the polarization state analyzer (6) further comprise a liquid crystal phase shifting element (13)(14) not arranged on the order of the measurement wavelength, the phase shifting element comprising at least two mutually rotating, spatially varying compensators (10) comprising a spatial array having a plurality of zones exhibiting independent optical axes but the same phase shift, The spatially varying compensator (10) imparts a plurality of spatially separated polarization states resulting in an intensity distribution across the cross section of the beam which, after interaction with the polarization state analyzer (6), is detected at a corresponding plurality of locations by a corresponding plurality of spatially distributed elements in the detector (8) and analyzed to determine sample properties. providing an ellipsometer; b) causing said electromagnetic radiation beam source (2) to provide a beam of electromagnetic radiation (3) directed to interact with said polarization state generator (4), to interact with a sample (5) accessed via a facility for interacting a collimated or non-collimated beam of electromagnetic radiation (3) with a sample at a known angle of incidence, to interact with said polarization state analyzer (6), and to cause said electromagnetic radiation to be incident on a multi-element detector (8); c) accessing data provided by said detector (8) in response to electromagnetic radiation input thereto; d) analyzing said data to characterize said sample (5); How to characterize the sample.

19. a) a') a facility for trapping the beam; b') Polarization state analyzer (4); c') a wavelength separation element (7), and d') Multi-element detector of electromagnetic radiation (8) A spectral polarimeter comprising: In use, said beam of electromagnetic radiation enters the spectral polarimeter and interacts with said polarization state analyzer (6), a wavelength separation element and said multi-element detector (8); The polarization state analyzer (6) includes a spatially varying compensator (10) that is an array of liquid crystal phase-shifting elements not organized on the order of the measurement wavelength; a polarization state analyzer (6) operable to provide a plurality of polarization states resulting in a spatial distribution of intensity across a cross-section of said beam, In use, the spectral polarimeter detects the intensity distribution at a number of positions by corresponding elements of the detector (8) and analyzes it to determine the polarization state of the beam for a range of wavelengths. Providing a spectral polarimeter; b) accessing a beam of electromagnetic radiation; c) accessing data provided by said detector (8) in response to a beam of electromagnetic radiation input thereto; d) analyzing said data to characterize said beam (5). A method for determining the polarization state of a beam of electromagnetic radiation over a range of wavelengths.

20. The ellipsometer further comprises at least one imaging element between the spatially varying compensator (10) and the multi-element detector (8) to improve the resolution of the correspondence between specific points on the spatially varying compensator (10) and specific points on the detector (8).

10. The ellipsometer of claim 1.

21. The beam source provided by the electromagnetic radiation beam source (2) comprises multiple wavelengths, the detector (8) is two-dimensional, the ellipsometer further comprises at least one wavelength separation element (7) in front of the detector (8) such that, in use, the polarization effects of the sample can be determined for multiple wavelengths at each position of the sample being investigated, and at least one additional focusing optic resolves the spectral variations caused by the wavelength separation element (7) onto one dimension of the detector (8), the at least one focusing optic being between an analyzer (11) and the multi-element detector (8).

21. An ellipsometer according to claim 1 or 20.

22. 3) Using multiple electromagnetic radiation beam sources (2) in combination to provide a broader or more preferred spectrum.

22. An ellipsometer according to any one of claims 1, 20 and 21.

23. The ellipsometer further includes a beam splitting element, and the resulting intensity profiles of both beams are detected to improve data quality or to provide an image of the beam profile or sample surface. An ellipsometer according to any one of claims 1 and 20 to 22.

24. The ellipsometer has a spatially varying compensator (10) present in both the polarization state generator (4) and the polarization state analyzer (6), and the spatial modulations of the two compensators are optically superimposed in a known relationship using imaging optics and / or low divergence illumination. An ellipsometer according to any one of claims 1 and 20 to 23.

25. each of the polarization state generator (4) and the polarization state analyzer (6) comprises at least one element having a plurality of positions (22)(13) or a plurality of elements each having at least one position (16), or a combination thereof; The spatial modulations of the elements of the polarization state generator (4) and the elements of the polarization state analyzer (6) are optically superimposed in a known relationship using imaging optics and / or low divergence illumination. be forgotten An ellipsometer according to any one of claims 1 and 20 to 24.

26. each of the polarization state generator (4) and the polarization state analyzer (6) comprises at least one element having a plurality of positions (13)(14) or a plurality of elements each having at least one position (16), or a combination thereof; The spatial modulations of the elements of the polarization state generator (4) and the elements of the polarization state analyzer (6) are optically superimposed in a known relationship using imaging optics and / or low divergence illumination. I was, The effective spatial modulation frequencies of the polarization state analyzer and the polarization state generator are in a ratio of 1:3, 3:1, 1:5, 5:1, 3:5, or 5:

3. An ellipsometer according to any one of claims 1 and 20 to 25.

27. The source of electromagnetic radiation (2) may be the output of a monochromator, an optical fiber, or a pinhole, so that the beam has desired spectral or spatial characteristics. An ellipsometer according to any one of claims 1 and 20 to 26.

28. A spatially varying compensator (10) is present in both the polarization state generator (4) and the polarization state analyzer (6), and the spatial modulation of the two compensators is achieved using imaging optics and / or low divergence illumination. are optically aligned in a known relationship using An ellipsometer according to any one of claims 1 and 20 to 27.

29. The spatially varying compensator imparts different effective modulation frequencies to the detector via magnifying optics, spatially varying changes in compensator properties, and / or focused or magnified illumination.

30. The ellipsometer of claim 28.

30. The effective spatial modulation frequencies of the polarization state analyzer and the polarization state generator are imaged onto the detector (8) in a ratio of 1:3, 3:1, 1:5, 5:1, 3:5, or 5:

3.

30. The ellipsometer of claim 29.

31. The beam source provided by the electromagnetic radiation beam source (2) comprises a plurality of wavelengths, the detector (8) is two-dimensional, and the ellipsometer further comprises at least one wavelength separation element (7) in front of the detector (8), such that, in use, the polarization effect of the sample can be determined for a plurality of wavelengths at each position of the sample being investigated.

20. The method of claim 18.

32. The beam source provided by the electromagnetic radiation beam source (2) comprises a plurality of wavelengths, the detector (8) is two-dimensional, and the ellipsometer further comprises at least one wavelength separation element (7) in front of the detector (8) such that, in use, it is possible to determine the polarization effect of the sample for a plurality of wavelengths at each position of the sample being investigated, the at least one wavelength separation element (7) being selected from the group consisting of:

32. The method of any one of claims 18 and 31 , Planar or curved diffraction gratings; A dispersing prism, and An attenuating or reflective filter element that transmits, blocks, or reflects different wavelengths at its different positions.

33. The electromagnetic radiation beam source (2) is selected from the group consisting of:

33. The method according to any one of claims 18, 31 and 32, Broadband or monochromatic lasers; broadband or narrowband LEDs; Monochromator; Broadband light source; FTIR light source; Globar light source; Incandescent light source; and Arc lamp.

34. The angle of incidence of the electromagnetic radiation beam on the surface of the sample is adjustable.

34. The method according to any one of claims 18, 31 to 33.

35. the electromagnetic radiation beam provided by said electromagnetic radiation beam source (2) does not approach the sample surface along a trajectory perpendicular or substantially perpendicular to the sample surface.

35. The method according to any one of claims 18, 31 to 34.

36. The ellipsometer is characterized by at least one selection from the group consisting of: The method according to any one of claims 18, 31 to 35, the light source does not include one or more lasers; and There is no in-line combination of a slit and a wedge-shaped compensation element between the light source and the sample.

37. The ellipsometer further comprises at least one imaging element between the spatially varying compensator (10) and the multi-element detector (8) to improve the resolution of the correspondence between specific points on the spatially varying compensator (10) and specific points on the detector (8).

20. The method of claim 18.

38. 2) the beam source provided by the electromagnetic radiation beam source (2) comprises multiple wavelengths, the detector (8) is two-dimensional, the ellipsometer further comprises at least one wavelength separation element (7) in front of the detector (8) such that, in use, the polarization effect of the sample can be determined for multiple wavelengths at each position of the sample being investigated, and at least one additional focusing optic resolves the spectral variations caused by the wavelength separation element (7) onto one dimension of the detector (8), the at least one focusing optic being between an analyzer (11) and the multi-element detector (8).

38. The method of any one of claims 18 and 37.

39. Using multiple electromagnetic radiation beam sources (2) in combination to provide a broader or more preferred spectrum 39. The method of any one of claims 18, 37 and 38.

40. The ellipsometer further includes a beam splitting element, and the resulting intensity profiles of both beams are detected to improve data quality or to provide an image of the beam profile or sample surface.

40. The method according to any one of claims 18, 37 to 39.

41. The ellipsometer comprises a spatially varying compensator (10) present in both the polarization state generator (4) and the polarization state analyzer (6), and the spatial modulations of the two compensators are optically superimposed in a known relationship using imaging optics and / or low divergence illumination.

41. The method according to any one of claims 18, 37 to 40.

42. each of the polarization state generator (4) and the polarization state analyzer (6) comprises at least one element having a plurality of positions (22)(13) or a plurality of elements each having at least one position (16), or a combination thereof; The spatial modulations of the elements of the polarization state generator (4) and the elements of the polarization state analyzer (6) are optically superimposed in a known relationship using imaging optics and / or low divergence illumination. be forgotten 42. The method according to any one of claims 18, 37 to 41.

43. each of the polarization state generator (4) and the polarization state analyzer (6) comprises at least one element having a plurality of positions (13)(14) or a plurality of elements each having at least one position (16), or a combination thereof; The spatial modulations of the elements of the polarization state generator (4) and the elements of the polarization state analyzer (6) are optically superimposed in a known relationship using imaging optics and / or low divergence illumination. I was, The effective spatial modulation frequencies of the polarization state analyzer and the polarization state generator are in a ratio of 1:3, 3:1, 1:5, 5:1, 3:5, or 5:

3.

43. The method according to any one of claims 18, 37 to 42.

44. The source of electromagnetic radiation (2) may be the output of a monochromator, an optical fiber, or a pinhole, so that the beam has desired spectral or spatial characteristics.

44. The method according to any one of claims 18, 37 to 43.

45. A spatially varying compensator (10) is present in both the polarization state generator (4) and the polarization state analyzer (6), and the spatial modulation of the two compensators is achieved using imaging optics and / or low divergence illumination. are optically aligned in a known relationship using 45. The method according to any one of claims 18, 37 to 44.

46. The spatially varying compensator imparts different effective modulation frequencies to the detector via magnifying optics, spatially varying changes in compensator properties, and / or focused or magnified illumination.

46. ​​The method of claim 45.

47. 11) In the above selection 10), the effective spatial modulation frequencies of the polarization state analyzer and the polarization state generator are imaged onto the detector (8) in a ratio of 1:3, 3:1, 1:5, 5:1, 3:5, or 5:

3.

47. The method of claim 46.

48. a) a source of an electromagnetic radiation beam (2); b) a polarization state generator (4); c) equipment for interacting a collimated or non-collimated beam of electromagnetic radiation (3) with a sample (5) at a known angle of incidence; d) a polarization state analyzer (6), and e) Multi-element detector of electromagnetic radiation (8) Equipped with In use, an electromagnetic radiation beam (3) is generated by the electromagnetic radiation beam source (2) and is caused to interact with the polarization state generator (4), the sample (5), the polarization state analyzer (6) and the multi-element detector (8); the polarization state generator (4) and / or the polarization state analyzer (6) further comprise a liquid crystal phase shifting element (13)(14) not arranged on the order of the measurement wavelength, a spatially varying compensator (10) being a phase shifting element with a spatial array having at least two mutually rotating, independent optical axes but a plurality of zones exhibiting the same phase shift, the at least one spatially varying compensator (10) imparts a plurality of spatially separated polarization states resulting in an intensity distribution across a cross section of the beam which, after interaction with the polarization state analyzer (6), is detected at a plurality of corresponding positions by a corresponding plurality of spatially distributed elements in the detector (8); The sample is analyzed to determine characteristics, A spatially varying compensator (10) is present in both the polarization state generator (4) and the polarization state analyzer (6), and the spatial modulation of the two compensators is achieved using imaging optics and / or low divergence illumination. , which are optically superimposed in a known relationship using Ellipsometer.

49. The spatially varying compensator imparts different effective modulation frequencies to the detector via magnifying optics, spatially varying changes in compensator properties, and / or focused or magnified illumination.

49. The ellipsometer of claim 48.

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