Multi-incident angle semiconductor metrology systems and methods

Abstract

To solve the problem in which improvement in a SE measurement tool is continuously demanded and even if a target feature is different, these SE data can be readily separated.SOLUTION: An ellipsometer device includes: a high-luminance light source 106 that provides an irradiation beam of selectable multiple wavelengths within a range from a far ultraviolet wavelength to an infrared wavelength; an irradiation optical system 102 that, in order to provide a spectroscopic ellipsometry, guides the irradiation beam toward a sample at selectable each set of an angle of incidence (AOI) or azimuth angle (AZ) and a polarization state, and includes an apodizer for controlling a spot diameter of the illumination beam hitting the sample at each selectable set of the angle of incidence or the azimuth angle; a collection optical system 104 that, in each selectable set of the angle of incidence or azimuth angle and polarization state, guides an output beam from the sample responding to the irradiation beam toward a detector generating an output signal or output image on the basis of the output beam; and a control unit that characterizes a feature of the sample on the basis of the output signal or output image.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to (i) U.S. Provisional Patent Application No. 61 / 752,202, entitled MULTIPLE INCIDENCE ANGLE SEMICONDUCTOR METROLOGY SYSTEM, filed Jan. 14, 2013, by David Y. Wang et al., and (ii) U.S. Provisional Patent Application No. 61 / 878,561, entitled MULTIPLE INCIDENCE ANGLE SEMICONDUCTOR METROLOGY SYSTEM AND METHOD, filed Sep. 16, 2013, by David Y. Wang et al., the entire contents of which are hereby incorporated by reference for all purposes.

[0002] The present invention relates generally to the field of semiconductor metrology systems, and more particularly to ellipsometer systems, reflected light measurement systems, and dispersed light measurement systems. [Background technology]

[0003] The ever-increasing demand for smaller semiconductor devices requires improved semiconductor wafer metrology systems. Fabricating semiconductor devices (such as logic devices and memory devices) typically requires processing semiconductor wafers using multiple semiconductor fabrication processes to produce semiconductor devices with various shapes and multiple layers. It is also possible to fabricate multiple semiconductor devices side-by-side on a single semiconductor wafer, and then separate them into individual semiconductor devices.

[0004] Metrology processes are used at various steps in the semiconductor manufacturing process to monitor and control the processing of one or more semiconductor layers. For example, metrology processes are used to measure one or more characteristics of a wafer, such as the dimensions of features formed on the wafer during the process (e.g., line width, thickness, angle, etc.), whose quality can be determined by measuring one or more characteristics. In the above configurations, a given semiconductor sample may include a set of metrology targets, where the sample includes a film stack or two-dimensional and three-dimensional patterned structures surrounded by one or more materials having various geometries and properties.

[0005] Spectroscopic ellipsometry (SE) metrology involves extracting light reflected from points with different optical constants on a measurement target. The SE data of the measurement target is used to determine the characteristics of the wafer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] US Patent Application Publication No. 2009 / 0279090 Summary of the Invention [Problem to be solved by the invention]

[0007] There is a continuing demand for improved SE metrology tools, which, for example, would allow for easy separation of SE data for different target characteristics. [Means for solving the problem]

[0008] The following presents a simplified summary of the disclosure in order to provide a basic understanding of certain embodiments of the invention. This "Summary" is not an extensive overview of the disclosure, nor does it identify key / critical elements of the invention or delineate the scope of the invention. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0009] In one embodiment, an ellipsometer apparatus for measuring semiconductor samples is disclosed. The apparatus includes an illumination optics module that provides an illumination beam at multiple selectable wavelengths ranging from vacuum ultraviolet (VUV) to infrared (IR) wavelengths and directs the illumination beam toward the sample at multiple angles of incidence (AOI) and / or azimuth angles (AZ), and a collection optics module that collects an output beam from the sample at multiple discrete ranges of angles of incidence and / or azimuth angles and directs the output beam to a detector module. The discrete ranges are collected one at a time, and the output beam is responsive to the illumination beam impinging on the sample. The illumination optics module includes a polarization generating optic that generates multiple polarization states for the illumination beam, and the collection optics module includes an ellipsometric optic that analyzes the polarization state of the output beam. The illumination optics module and the collection optics module include reflective optics between the polarization generating optic and the ellipsometric optic. The apparatus further includes a detection module that receives and detects the output beam from the sample at a discrete range of incidence angles and / or azimuth angles and polarization states, and generates a plurality of signals based on the output beam at the discrete range of incidence angles and / or azimuth angles and polarization states. The apparatus further includes one or more controls configured to control one or more of: selecting a wavelength range; selecting one or more discrete ranges of incidence angles and / or azimuth angles for collecting the output beam; selecting a polarization state; and analyzing the signals at the discrete ranges of incidence angles and / or azimuth angles and polarization states to determine a characteristic of the sample. In one embodiment, the sample is one or more objects on a semiconductor wafer.

[0010] In a specific embodiment, the discrete ranges of incidence angles and / or azimuthal angles are spatially separated from one another. In another aspect, the wavelength range is from about 150 nm to about 2000 nm. In another aspect, the illumination optics module includes a high brightness laser sustained plasma (LSP) source that generates the illumination beam. In one aspect, the LSP source has a power of about 0.1 W / nm / cm 2 The apparatus produces an illumination beam with a peak brightness of at least 100 nm / sr. In one aspect, the discrete portions of the incidence angles or azimuth angles are each separated by at least 0.1°. In another aspect, the discrete range of incidence angles and / or azimuth angles includes incidence angles greater than about 60°. In a specific aspect, the discrete range of incidence angles and / or azimuth angles includes a plurality of discrete ranges of azimuth angles from 0° to 360°. In this embodiment, the apparatus may include a positioning mechanism to rotate the sample to obtain the discrete range of azimuth angles from 0° to 360°. In another aspect, the discrete range of incidence angles and / or azimuth angles includes a plurality of discrete ranges of azimuth angles from 0° to 90°.

[0011] In one embodiment, the illumination optics module includes a plurality of fixed apertures or a movable aperture for providing illumination beams at each of the discrete ranges of incidence angles and / or azimuth angles substantially the same as those collected and detected by the collection optics module. In one aspect, the illumination optics module includes a plurality of fixed apertures for providing illumination beams at each of the discrete ranges of incidence angles and / or azimuth angles and a shutter covering each of the fixed apertures. In another aspect, the illumination optics module is further configured to simultaneously provide illumination beams at a range of incidence angles and / or azimuth angles substantially including the discrete ranges of incidence angles and / or azimuth angles collected and detected by the collection optics module one by one. In another embodiment, the collection optics module includes a plurality of fixed apertures for collecting output beams at each of the discrete ranges of incidence angles and / or azimuth angles and a shutter covering each of the fixed apertures. In another embodiment, the collection optics module includes either a movable aperture or multiple fixed apertures, each with a shutter, for collecting one output beam at each of the discrete ranges of incidence angles and / or azimuth angles.

[0012] In a specific embodiment, the polarization generating optics includes a polarizer and a first compensator in the illumination optics module and the ellipsometric optics includes a second compensator and an analyzer in the collection optics module, and selecting the polarization state includes rotating or keeping stationary any one or more of the polarizer, the first compensator and the second compensator, and the analyzer. In another embodiment, the polarization generating optics includes a polarizer and an analyzer, and selecting the polarization state includes rotating the polarizer and keeping the analyzer stationary. In a further aspect, the ellipsometric optics further includes a collection compensator, and selecting the polarization state further includes rotating the collection compensator. In a further aspect, the illumination optics module includes an apodizer to minimize a point spread function of the focal point on the object at the sample for each discrete range of incidence angles and / or azimuth angles. Illumination (or collection) apodization can generally be defined as transforming the light distribution at the entrance pupil of an optical system (e.g., using a mask to change the amplitude and / or phase of the illumination or collection beam), thereby changing the intensity profile of the illumination (or collection) beam. In yet another aspect, the polarization generating optic further includes an illumination compensator, and selecting the polarization state further includes rotating the illumination compensator.

[0013] In another example, the polarization generating optics includes a polarizer and an illumination compensator, and the ellipsometric optics includes an analyzer, and selecting the polarization state includes rotating the illumination compensator and holding the polarizer and the analyzer stationary. In a further aspect, the ellipsometric optics further includes a collection compensator, and selecting the polarization state further includes rotating the collection compensator. In another embodiment, the polarization generating optics includes a polarizer, and the ellipsometric optics includes an analyzer, and selecting the polarization state includes holding the polarizer stationary and rotating the analyzer.

[0014] In a specific embodiment, the illumination optics module includes one or more beam shaping optical elements for shaping the illumination beam and controlling the point spread function of the focal spot focused on the target on the sample for each discrete range of incidence angles and / or azimuth angles. For example, the one or more beam shaping elements are configured to reduce the irradiance at a predetermined distance from the center of the illumination spot produced by the illumination beam on the sample to less than a predetermined value of the peak irradiance at the center of the illumination spot.

[0015] In an exemplary embodiment, the one or more beam shaping elements are apodizers, each having a respective non-reconfigurable optical function. The apparatus further includes a positioning mechanism for moving a selected one of the apodizers to or near a plane conjugate to a pupil of the illumination beam, and the controller is further configured to cause the positioning mechanism to move the selected one of the apodizers. The apodizers provide a predefined illumination profile for all of a discrete range of angles of incidence and / or azimuth angles.

[0016] In another embodiment, the one or more beam shaping elements is a dynamically adjustable apodizer disposed at or near a plane conjugate to a pupil of the illumination beam, the dynamically adjustable apodizer configured to provide a predefined illumination profile for all of a discrete range of angles of incidence and / or azimuth angles, and the controller is further configured to adjust the dynamically adjustable apodizer.

[0017] In another embodiment, the collection optics module includes one or more apodizers located at or near a plane conjugate to the collection pupil or movable to that location, the apodizers providing predefined collection profiles for all of a discrete range of incidence angles and / or azimuth angles.

[0018] In another embodiment, the illumination optics module includes (i) a first off-axis parabolic (OAP) mirror and (ii) a first translation mirror movable to receive the illumination beam at a plurality of positions and direct the illumination beam to a plurality of positions on the first OAP mirror so that the first OAP reflects the illumination beam to the sample one at a discrete range of incidence angles and / or azimuth angles. In this embodiment, the collection optics module includes (i) a detector, (ii) a second OAP, and (iii) a second translation mirror movable to receive the output beam at a plurality of positions and direct the output beam to a plurality of positions on the second OAP mirror so that the second OAP reflects the output beam to the detector one at a discrete range of incidence angles and / or azimuth angles.

[0019] In another embodiment, the illumination optics module includes a beam splitter, an off-axis parabolic (OAP) mirror, and a translation mirror movable to receive the illumination beam through the beam splitter at a plurality of translation positions of the translation mirror and direct the illumination beam to a plurality of corresponding positions on the OAP mirror so that the OAP reflects the illumination beam to the sample one at a discrete range of incidence angles and / or azimuth angles. The collection optics module includes (i) a beam splitter, (ii) an OAP, (iii) a translation mirror, and (iv) a spherical mirror that reflects the output beam back to the sample, thereby causing a second output beam to exit the sample and reflect from a corresponding position on the OAP and then reflects from the translation mirror to the beam splitter at a plurality of translation positions to a detector to collect the second output beam one at a discrete range of incidence angles and / or azimuth angles.

[0020] In another aspect, the collection optics module can be further configured to collect zeroth order light from the output beam for brightfield measurements and non-zeroth order light from the output beam for darkfield measurements by illuminating at one or more angles of incidence and collecting over one or more different angles of incidence. In one embodiment, the collection optics module collects an angle of incidence (azimuth) that is the same as the angle of incidence (azimuth) of the illumination reflected from the sample. In another example, the collection optics module collects an angle of incidence (azimuth) that is different from the angle of incidence (azimuth) of the illumination reflected from the sample. In yet another example, the collection optics module includes a dispersive element that disperses the light into a spectrum. In another embodiment, the illumination pupil and collection pupil of the device are arranged to set the illumination numerical aperture and the collection numerical aperture, and the illumination field stop and collection field stop of the device are arranged to set the source size and the image size.

[0021] In an alternative embodiment, the apparatus includes (i) an illumination optics module that provides an illumination beam at multiple selectable wavelengths in a range from vacuum ultraviolet (VUV) to infrared (IR) wavelengths and directs the illumination beam toward the sample at multiple angles of incidence (AOI) and / or azimuthal angles (AZ), and (ii) a collection optics module that collects an output beam from the sample at substantially all angles of incidence or azimuthal angles and substantially simultaneously directs the output beam to one or more detectors, the output beam being responsive to the illumination beam impinging on the sample. The illumination optics module includes a polarization generating optical element that generates multiple polarization states for the illumination beam, the collection optics module includes a polarimetric optical element that analyzes the polarization state of the output beam, and the illumination optics module and the collection optics module include reflective optical elements between the multiple polarization state generating optical element and the polarization state analyzing optical element. The apparatus also includes one or more detectors that receive and detect the output beam from the sample at the angles of incidence and / or azimuth angles and polarization states and generate a plurality of signals or images based on the output beam at the angles of incidence and / or azimuth angles and polarization states, and one or more controllers that are each configured to control one or more of: selecting a wavelength range; selecting a polarization state; and analyzing the signals or images at the wavelengths, angles of incidence and / or azimuth angles, and selected polarization states to determine characteristics of the sample.

[0022] In one embodiment, the collection optics includes one or more dispersive elements that disperse the wavelengths in a wavelength direction and disperse the incidence angle and / or azimuth angle in an incidence angle / azimuth direction, where the wavelengths and the incidence angle and / or azimuth angle are dispersed along two different detection directions. In a further embodiment, the two different directions are mutually orthogonal. In another embodiment, the one or more dispersive elements have two different optical powers for the two different directions. In yet another embodiment, the one or more detectors comprise a plurality of detectors, each detector configured to determine the dispersed wavelengths and integrate over one of the separate incidence angle regions. In a further embodiment, the collection optics module further includes a subdivision optic that divides the output beam from the one or more dispersive elements into separate incidence angle regions, each output to one of the detectors. In another embodiment, the collection optics further includes a re-imaging optic located between the wavelength plane and the incidence angle and / or azimuth plane, where the re-imaging optic is configured to re-image the wavelength plane onto each detector.

[0023] In another embodiment, the collection optics module includes an incidence angle / azimuth mask in a plane conjugate with the pupil for selectively transmitting specific incidence angle / azimuth regions from a plurality of spatially separated incidence angle / azimuth regions in the output beam, and a detector for receiving the specific incidence angle / azimuth regions, determining the dispersed wavelengths, and integrating the determined wavelengths over the specific incidence angle / azimuth regions, and the controller is further configured to select one specific incidence angle / azimuth region at a time. In a further aspect, the wavelength plane is located in front of the incidence angle / azimuth plane. In another aspect, the incidence angle / azimuth mask is comprised of a plurality of fixed apertures, each with a shutter. In yet another embodiment, the incidence angle / azimuth mask is comprised of a fixed movable aperture.

[0024] In another embodiment, the collection optics module includes a single detector that determines the dispersed wavelength and integrates over the different incidence angle regions, with non-pixel regions between adjacent ones of the different incidence angle regions that do not resolve or analyze the incidence angle. In another aspect, the collection optics includes a beam splitter that splits the output beam into a first output beam and a second output beam, a first dispersive element that receives the first output beam and disperses the wavelength and incidence angle of the output beam along two different detection directions of the first detector, and a second dispersive element that receives the second output beam and disperses the wavelength and azimuth angle of the output beam along two different detection directions of the second detector. In another embodiment, the wavelength plane is coplanar with the incidence angle / azimuth angle plane. In another aspect, the collection optics module includes a detector with at least two registers that process parallel data from the two different incidence angle regions. In another embodiment, the illumination optics and the collection optics include the features described above.

[0025] In another embodiment, the apparatus includes: (i) one or more high intensity light sources providing illumination beams at a plurality of selectable wavelengths in a range from vacuum ultraviolet (VUV) to infrared (IR) wavelengths; (ii) illumination optics directing the illumination beams toward the sample at a plurality of selectable sets of angles of incidence (AOI) and / or azimuth angles (AZ) and a plurality of polarization states, the illumination optics including at least one apodizer controlling a spot diameter of the illumination beam on the sample at each of the selectable sets of angles of incidence and / or azimuth angles; (iii) collection optics directing an output beam emerging from the sample in response to the illumination beam toward a detector at each of the selectable sets of angles of incidence or azimuth angles and polarization states; (iv) a detector generating an output signal or an output image based on the output beam; and (v) a controller for characterizing a feature of the sample based on the output signal or output image as a function of wavelength, angles of incidence and / or azimuth angles, and / or polarization states, or a combination thereof.

[0026] In one embodiment, the one or more light sources include a laser sustained plasma (LSP) source. In a specific implementation, the at least one apodizer comprises a set of apodizers each having a non-reconfigurable optical function and each movable in and out of the illumination pupil plane, with each fixed apodizer configured to control the spot diameter for each of a selectable set of incidence angles or azimuth angles. In another aspect, the at least one apodizer is disposed at or near a plane conjugate with the illumination pupil plane to control the spot diameter for all of a selectable set of incidence angles and / or azimuth angles. In another aspect, the at least one apodizer is a dynamically adjustable apodizer that can be configured to control the spot diameter by reducing the irradiance at a predetermined distance away from the center of the illumination spot below a predetermined value of the peak irradiance at the center of the illumination spot. In another embodiment, the at least one apodizer is configured to control the spot diameter by suppressing side lobes in the illumination beam. In yet another example, the at least one apodizer can be further configured for a plurality of different targets on the sample.

[0027] In another aspect, the illumination optics includes a scanning mirror that scans the illumination beam on the sample through each of the selectable sets of incidence angles or azimuth angles, and the collection optics includes an incidence angle / azimuth angle selector for determining each of the selected sets of incidence angles or azimuth angles one by one. In a further aspect, the incidence angle / azimuth angle selector includes a plurality of fixed apertures or at least one movable aperture, each with a shutter. In another aspect, the at least one apodizer is a dynamically adjustable apodizer. In one example, the dynamically adjustable apodizer is a spatial light modulator (SLM). In another embodiment, the at least one apodizer is configurable to form a plurality of binary amplitude patterns for each of the selectable sets of incidence angles or azimuth angles. In another example, the at least one apodizer is configured to form a plurality of amplitude patterns for each of the selectable sets of incidence angles or azimuth angles, and the at least one amplitude pattern is continuously variable.

[0028] In an alternative embodiment, the invention relates to a method for performing spectroscopic ellipsometry in a metrology system, the method including: (i) generating illumination light at multiple wavelengths, (ii) selecting a plurality of different polarization states for the illumination light, (iii) selecting a plurality of angles of incidence (AOI) or azimuthal angles (AZ) for the illumination light, (iv) shaping and steering the illumination light to form spots on a target at multiple wavelengths, different polarization states, and angles of incidence or azimuthal angles, (v) collecting and detecting output light emerging from a sample in response to the illumination light, and generating a signal or image based on the detected output light as a function of each wavelength, different polarization states, and angles of incidence or azimuthal angles, and (vi) analyzing the signal or image to determine a characteristic of the sample.

[0029] These and other aspects of the invention are further described below with reference to the figures. [Brief description of the drawings]

[0030] [Figure 1] 1 illustrates a spectroscopic ellipsometry (SE) tool for collecting light at a specific angle of incidence (AOI) in accordance with an embodiment of the present invention. [Diagram 2] 1 illustrates an SE tool for simultaneously detecting multiple incidence angles according to a second embodiment of the present invention. [Figure 3A] 1 is a simplified diagram of an example of an SE tool for simultaneously collecting multiple incidence angle regions with multiple detectors according to a specific embodiment of the present invention. [Figure 3B] 1 is a simplified diagram of a second example of an SE tool with an incidence angle mask configurable to selectively detect an incidence angle range among multiple incidence angles in accordance with another specific embodiment of the present invention. [Figure 3C] FIG. 13 illustrates the simultaneous collection of multiple incidence / azimuth angle regions on a single detector according to an alternative embodiment. [Figure 3D] 1 illustrates a collection optics system for simultaneously collecting incident and azimuthal angles after dispersion according to one embodiment. [Figure 4A] 1 illustrates a configurable SE tool with a configurable set of apodizers according to another embodiment of the present invention. [Figure 4B] 1 illustrates a configurable SE tool with a dynamically adjustable apodizer in accordance with an alternative embodiment of the present invention. [Figure 5A] FIG. 1 is a side view of an exemplary aperture system according to one embodiment. [Figure 5B] FIG. 13 is a side view of an exemplary aperture system according to a second embodiment. [Figure 6A] FIG. 2 is a perspective view of an illumination selector according to an embodiment of the present invention; [Figure 6B] FIG. 13 illustrates the combination of three aperture configurations to obtain a second embodiment of the aperture configuration. [Figure 7A] 1 illustrates a configurable metrology tool with an off-axis parabolic (OAP) mirror in accordance with another embodiment of the present invention. [Figure 7B] 1 illustrates a configurable dual-path metrology tool with an off-axis parabolic (OAP) mirror in accordance with an alternative embodiment of the present invention. [Figure 8] 4 is a flowchart showing an SE measurement procedure according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be practiced without some or all of these specific details. In other instances, well-known components or process steps have not been described in detail in order to avoid unnecessarily obscuring the present invention. While the present invention will be described in connection with specific embodiments, it will be understood that it is not intended to limit the invention to these embodiments.

[0032] One issue in the use of spectroscopic ellipsometry (SE) systems is related to the combination of detected data. The measured ellipsometric parameters from a particular sample (e.g., semiconductor wafer or reticle) depend on multiple metrology parameters, such as wavelength (λ) and the x,y position of the object. Typically, the ellipsometric data for different tool settings (e.g., λ and object position) are collected separately and input into a model (e.g., CD and overlay) to infer the object properties. As the object becomes more complex, the collected data to change the object properties become closely related or insufficient. As a result, the model is unable to accurately determine the object properties.

[0033] Although SE systems that can be configured to have different specific narrow ranges of incidence angles can result in uncorrelated parameters of interest, such systems may not be able to provide small spot diameters for each narrow range of incidence angles and resulting NA. For example, incidence angle-selective SE systems may not include mechanisms for obtaining small enough spot diameters that may be useful for measuring certain small features (e.g., 40 microns by 40 microns or smaller). Furthermore, such SE systems may be limited in the range of incidence angles and may not be able to approach Brewster's angle, which may not provide high sensitivity for certain applications.

[0034] For simplicity, the term "angle of incidence" is used herein as an abbreviation for "discrete narrow range of angles of incidence." Similarly, the term "discrete angles of incidence" is used synonymously with the term "discrete range of angles of incidence." Some SE systems may be configured with a single angle of incidence or with discrete angles of incidence. However, SE systems generally do not actually allow only a single angle of incidence or only discrete angles of incidence, but instead allow a narrow range of angles of incidence centered around a "selected" single angle of incidence or a discrete angle of incidence or include a "selected" single angle of incidence. Other SE systems allow a narrow range of angles of incidence to be entered as a setup or recipe parameter, rather than a single angle of incidence or a discrete angle of incidence. The angle of incidence is the angle with respect to the normal to the sample. The azimuth angle is the angle with respect to one of the mutually orthogonal axial directions, such as x and y, that define a two-dimensional plane of the sample surface.

[0035] Certain ellipsometric embodiments of the present invention provide an ellipsometer that obtains measurements at multiple angles of incidence (AOI) and azimuth angles (AZ), either simultaneously or sequentially, thereby facilitating de-correlation between target properties. The ellipsometer tool may also include optics for generating and analyzing polarization states. These components may be configured to determine all or a portion of the Mueller matrix elements of the target. The tool may also include a high-intensity light source that is configurable for a wide range of wavelengths, including vacuum ultra violet (VUV), visible, near infrared (NIR), and infrared (IR). In certain embodiments, the SE system provides a variety of selectable angle of incidence configurations (including angles of incidence and multiple angles of incidence), simultaneous and sequential angles of incidence, configurable polarization states for ellipsometrically analyzing the Mueller matrices, and selectable wavelength ranges from VUV to NIR. The illumination side of the present system embodiments (as well as other embodiments described herein) may include reflective optics to work from VUV to UV and provide broad color correction across the full range from VUV to IR.

[0036] In certain embodiments, spectroscopic ellipsometry (SE) can be performed at multiple angles of incidence and multiple azimuth angles, thereby improving measurement repeatability and stability by using fixed illumination and collection pupils, and fixed illumination and collection field stops. FIG. 1 illustrates a spectroscopic ellipsometry (SE) tool 100 for collecting light at a specific angle of incidence (AOI) according to one embodiment of the present invention. In general, the metrology tool may include illumination optics 102 that provide high-intensity illumination light at a configurable wavelength, and collection optics 104 that detect light from objects on a sample (specimen) 132 at a spatially separated discrete range of angles of incidence (or a discrete range of azimuth angles), either singly or simultaneously. Illumination optics 102 and collection optics 104 may also be configured to generate and collect light at various polarization states, including polarization states for determining all or a portion of the Mueller matrix of the object.

[0037] As shown, the illumination optics 102 includes one or more light sources (e.g., light source 106) that generate an illumination beam. In the illustrated embodiment, the one or more illumination sources 102 may include one or more broadband light sources covering wavelengths ranging from vacuum UV to near infrared (e.g., from about 150 nm to about 2000 nm). In one example, the illumination source is a laser sustained (LSP) source that generates high brightness light. One example LSP is the EQ-1000 available from Energetiq Technology, Inc. (Woburn, Massachusetts). Some embodiments of LSPs are described in U.S. Patent Publication No. 2011 / 0204265, entitled "LASER DRIVEN LIGHT SOURCE," filed May 3, 2011 by Donald K. Smith et al., and U.S. Patent Publication No. 2009 / 0032740, entitled "LASER DRIVEN LIGHT SOURCE," filed July 2, 2008 by Donald K. Smith et al., both of which are incorporated herein by reference. Other light sources may include solid state lasers or other types of lasers.

[0038] In one embodiment, the one or more light sources also have a luminance of at least 0.1 W / (nm cm) for a simultaneous incidence angle in the range of 57° to 73°. 2In another embodiment, the one or more light sources also have a peak luminance of at least 0.1 W / (nm cm) at wavelengths near 190 nm. 2 Sr).

[0039] Fast feedback may also be applied to the light source of the measurement system to stabilize the light source power and wavelength. Some mechanisms for controlling such LSP and other broadband light sources are further described in U.S. Patent Application No. 2011 / 0069312, entitled "Measurement Systems and Methods," filed Aug. 31, 2010 by Daniel Kandel et al., which is incorporated herein by reference. The light source may also consist of a xenon lamp and / or a deuterium lamp.

[0040] In another embodiment, the light source is comprised of multiple laser diodes in the form of different sets of laser diodes that can be selected to cover a range of wavelengths required for a particular metrology application. For example, these laser diode arrays provide wavelength ranges selectively obtained from the ultra-violet (UV), UV, visible (VIS) and near infrared (NIR) ranges. Some embodiments of laser diode arrays are further described in U.S. Application No. 13 / 924,216, entitled "Broadband Light Source for Wafer Inspection Tools Based on Diode Lasers," filed June 21, 2013 by Anant Chimmalgi et al., which is hereby incorporated by reference in its entirety.

[0041] The illumination optics 102 may also include ellipsometer illumination optics 108 for adjusting the illumination beam, such as by setting the position and size of an aperture and a field stop, and adjusting the illumination beam relative to a polarizer 110. The ellipsometer illumination optics 108 may generally be configured to perform any suitable beam shaping function, such as manipulating the beam shape by collimating, focusing, expanding, contracting, or otherwise modifying the beam shape.

[0042] The polarizer 110 may be configured to rotate to perform rotating polarizer ellipsometry (RPE) or fixed to perform other types of ellipsometry. The illumination optics may also include an illumination compensator 112 in the form of a waveplate (or a photoelastic, acousto-optic, liquid crystal light modulator, or other polarization-sensitive phase modulating device) in the illumination path. The illumination compensator 112 may be configured as fixed or rotating (e.g., for rotating compensator ellipsometry (RCE) mode). Rotating the compensator 112 and / or the polarizer 110 in this illumination path allows the polarization state of the illumination beam to be changed. These polarization states can include S and P polarization states, as well as more general polarization states. These polarization states may be selected to perform Mueller matrix-based ellipsometry, as described further herein.

[0043] The polarizer 110 and compensator 112 may be designed to work with broadband light ranging from VUV to NIR, for example, suitable polarizers include MgF2 Rochon prisms and suitable waveplates include MgF2 and quartz waveplates, in addition to other materials depending on the wavelength range.

[0044] The illumination optics may also include fixed or movable apertures and / or shutters to allow for selection of discrete angles of incidence or discrete azimuth angles. In the illustrated embodiment, mirrors 115, 116 are used to focus the illumination beam onto the sample 132, with aperture 114 defining one or more ranges of angles of incidence and / or azimuth angles to be focused onto the sample 132. For example, a non-reflective material can be patterned onto the mirror to provide a specific reflective aperture where there is no non-reflective material.

[0045] In the illustrated embodiment, the aperture element 114 includes a set of fixed apertures to provide a spatially discrete set of incidence or azimuth angles to the sample. Alternatively, the aperture element 114 may also include a shutter for each aperture to allow each set of discrete incidence or azimuth angles to be independently selected to illuminate the sample. In another embodiment, the aperture element 114 may include one or more movable apertures to select various spatially discrete ranges of incidence or azimuth angles. Some configurable apertures are further described in PCT International Application No. PCT / US2013 / 028650, filed March 1, 2013 by KLA-Tencor Corporation, which is incorporated herein by reference in its entirety.

[0046] In another embodiment, the aperture arrangement can also take the form of a transmissive aperture element, which is arranged such that the illuminating light passes through holes in an opaque material or a transmissive material patterned with an opaque material. The rays of the illuminating beam can then be focused at discrete angles of incidence and discrete azimuthal angles on the wafer, for example by a transmissive focusing element. However, a transmissive aperture element may not work well from the VUV to the UV.

[0047] In any aperture embodiment, the aperture elements are located at or near the pupil plane and are configured to transmit or reflect the illumination beam at a particular spatial location in the pupil plane, thereby allowing a discrete range of incidence angles or azimuth angles to be selected. In other words, the metrology system is capable of discretely selecting a range of incidence angles and azimuth angles for the illumination beam, either simultaneously (e.g., without the use of shutters or movable apertures) or one at a time (via shutters or movable apertures). For example, the discrete sets of incidence angles, each having an incidence angle range of about 8° or less, are separated by at least about 0.1° between each set, and together, the sets cover a range of about 50° to about 80°. In one embodiment, at least one of the selectable range of incidence angles is an incidence angle greater than about 60°. Similarly, the discrete ranges of azimuth angles may each have an azimuth angle range equal to or less than 20°, but are separated by at least about 0.1° between each set, and together, the sets cover a range of 0° to 360°.

[0048] The collection optics 104 may be configured to collect light from the sample 132 at discrete angles of incidence and discrete azimuth angles. That is, the collection optics 104 is sized to collect the detected light from the sample 132 (having a plurality of different angles of incidence and azimuth angles). In the illustrated embodiment, the mirrors 117, 118 collect the illumination beam that reflects off the sample 132 and direct the beam toward the detector 124. The aperture element 126 is configured to select various angles of incidence and azimuth angles. For example, one of three different collection apertures may be used to select one of three different sets of angles of incidence (collected at three different angles of incidence).

[0049] Optical elements may then be positioned to analyze the polarization state of the light reflected by the sample 132. For example, the second compensator 120 and analyzer 122 may be rotated or fixed in various configurations to collect different polarization states. The second compensator may take the form of a waveplate (or a photoelastic modulator, acousto-optic modulator, liquid crystal light modulator, or other polarization-sensitive phase modulating device).

[0050] In rotating polarizer ellipsometry (RPE) mode, only the polarizer rotates while other rotatable ellipsometry components (such as the illumination compensator in the illumination path, the analyzer and the collection compensator in the collection path) remain fixed. Other modes can include RPRC (rotating polarizer, rotating illumination or collection compensator and fixed analyzer) mode and RCRC (fixed polarizer, rotating illumination compensator, rotating collection compensator and fixed analyzer) mode. Other modes can include RCE (fixed polarizer, rotating illumination compensator and fixed analyzer), RCRC (fixed polarizer, rotating illumination compensator and rotating collection compensator, and fixed analyzer), or a combination of a fixed polarizer and a rotating analyzer. The system can include either the illumination compensator or the collection compensator, or can eliminate both compensators.

[0051] Any of the system embodiments described herein may be configurable for Mueller ellipsometry, where the sample is described by a 4×4 matrix, where each element in the matrix is ​​a set of spectra. Any combination of the polarizer 110, analyzer 122, first compensator 112, second compensator 120, and sample 132 may be rotated during the measurement. The polarization generating optics and the polarization analyzing optics may each be rotated at a selectable angular frequency. Different configurations are used to generate different numbers of harmonic spectra, some of which generate a sufficient number of harmonic spectra to completely determine the Mueller matrix of interest. Various techniques for performing ellipsometry using Mueller matrices are further described in U.S. Patent No. 8,446,584, entitled "Reconfigurable Spectroscopic Ellipsometer," by Shankar Krishnan, issued May 21, 2013, and incorporated herein by reference in its entirety.

[0052] The optical elements located between the polarizer 110 and the analyzer 122 may be reflective elements for reflecting the illumination light towards the sample and collecting the output light from the sample. Several different configurations of reflective optical elements in a spectroscopic ellipsometry tool are further described in U.S. Patent No. 5,608,526, issued March 4, 1997 to Piwonka-Corle et al., which is incorporated herein by reference for the purposes of providing further embodiments of various spectroscopic ellipsometry features, including light sources, optics for reflecting and focusing the illumination beam onto the sample, autofocus detection components, polarizer / compensator / analyzer configurations and arrangements, reference channel components for generating and detecting a reference illumination beam, control and processing mechanisms, spectrometer / detector arrangements, and spectrometer system components that may be utilized in the system embodiments described herein.

[0053] The collected light may then be received by a detector 124. In one embodiment, the detector is a spectrometer with a sufficiently high quantum efficiency over a wide range of wavelengths. The detector module may include a spectrometer slit and one or more reflecting mirrors that reflect the output beam through a prism that is configured to refract different wavelengths in different directions, thereby causing the light to impinge along different linear portions of the detector or sensor. Other detector module configurations are contemplated. In a specific embodiment, the detector may include one or more of the following UV-enhancing components: a charged coupled device (CCD)-based detector with a sufficiently high quantum efficiency over a wavelength range of about 190 nm to about 900 nm, a photodiode array with a sufficiently high quantum efficiency over a wavelength range of about 700 nm to about 2000 nm, a photodiode array with a sufficiently high quantum efficiency over a wavelength range of about 150 nm to about 400 nm, etc. Suitable detectors include charge coupled devices (CCDs), CCD arrays, time delay integration (TDI) sensors, TDI sensor arrays, photomultiplier tubes (PMTs), and other sensors.

[0054] The system 100 may also include a controller 130. The controller may include any suitable combination of software and hardware and is generally configured to control various components of the metrology system 100. For example, the controller may control selective activation of the light source 106, settings of the illumination polarizers and illumination compensators, settings of the detection compensators and detection analyzers, settings of the illumination apertures / shutters, etc. The controller 130 may also receive signals or image data generated by the detector 124 and may be configured to analyze the resulting signals or images to characterize the object or sample by determining sample parameters, or to determine whether a defect is present in the sample, or to characterize defects present in the sample.

[0055] System 100 may also include a positioning mechanism 131 that rotates, tilts, and / or translates various movable components (such as the sample stage, fixed aperture / mask, shutters, polarizers, analyzers, compensators, etc.) to various positions. By way of example, positioning mechanism 131 may include one or more motor mechanisms (such as screw drives and stepper motors, linear drives with position feedback, band actuators and stepper motors, etc.).

[0056] As with any system described herein, system 100 also preferably includes a purge system for filling the vacuum chamber with nitrogen gas or other gas suitable for operation in the vacuum UV. For operation at 150 nm, for example, the entire optical path is sealed in a chamber, which is filled with dry nitrogen gas. Exemplary purge systems and techniques are described in (i) U.S. Patent Application Publication No. 2004 / 0150820, filed Nov. 19, 2003, by Nikoonahad et al., and (ii) U.S. Patent No. 7,755,764, filed Jan. 24, 2008, both of which are incorporated herein by reference for such features.

[0057] Each controller described herein may be configured (e.g., with program instructions) to provide a user interface (e.g., on a computer screen) for displaying acquired test images and other metrology characteristics. The controller may also include one or more input devices (e.g., keyboard, mouse, joystick) for providing recipe input to the user. Such recipe input may include selecting wavelength ranges, angles of incidence / azimuth, and polarization states of the incident or collected light, in addition to detection parameters. The controller typically includes one or more processors. The processors are connected to input / output ports and one or more memories via a suitable bus or other communication mechanism.

[0058] Such information and program instructions may be implemented in a specially configured computer system. Such a system includes program instructions / computer code for performing the various operations described herein, which may be stored on a computer-readable medium, such as, but not limited to, magnetic media, such as hard disks, floppy disks, and magnetic tapes; optical media, such as CD-ROM disks; magneto-optical media, such as optical disks; and hardware devices specially configured to store and execute program instructions, such as read-only memory (ROM) devices and random access memory (RAM). Exemplary program instructions include both machine code (such as code generated by a compiler) and files containing high-level code that may be executed by the computer using an interpreter.

[0059] It should be noted that the above figures and descriptions should not be construed as being limited to any particular components of the system, but rather that the system may be embodied in many other forms. For example, it is contemplated that the metrology tool may include any number and type of suitable components arranged to determine characteristics and properties of a sample of interest. As an example, the metrology tool may include one or more components for performing VUV to NIR spectroscopic ellipsometry, reflectometry, or diffusive light measurements.

[0060] In another exemplary embodiment of the SE tool, the tool's detector system simultaneously resolves wavelength and incidence or azimuth angles. FIG. 2 illustrates an SE tool 200 that can be configured to simultaneously detect multiple incidence angles according to a second embodiment of the present invention. In this example, light reflected from the sample 132 at various incidence or azimuth angles is collected by collection optics 204 and sent to a detector module 224. In the illustrated embodiment, collection optics 204 includes collection mirrors 226, 118 that focus the collected light onto dispersion optics and detector module 224. In an alternative embodiment, the detected light is not spatially resolved into discrete incidence or azimuth angles.

[0061] Any suitable collection mechanism for mapping wavelength and incidence / azimuth angles to two different directions in a plane (e.g., orthogonal x and y directions) may be incorporated into the SE tool. Typically, system 200 may include an optical collection system with separate optical powers (e.g., cylindrical, annular, etc.) in two different directions (e.g., x and y directions) to map wavelength and incidence angle (or azimuth) to two different directions of a two-dimensional detector. As shown, dispersion optics and detector module 224 provides the functionality of a two-dimensional spectrometer (shown enlarged at 227) with one axis for incidence / azimuth angles and another axis for wavelength. The dispersion optics may be configured to have a refractive index in the wavelength direction that places the detector at or near a plane conjugate to the field stop, and a refractive index in the incidence angle direction that places the detector plane at or near a conjugate to the pupil plane. Alternatively, the incidence angle in this embodiment may be replaced by an azimuth angle.

[0062] In the illustrated embodiment, the dispersive optics and detector module 224 includes a dispersive element for receiving the detected beam at the spectrometer entrance and conditioning the beam for reception by a detector that maps the light as a function of wavelength onto a first axis (e.g., in the X direction) and maps the detected light as a function of incidence / azimuth onto a second axis (e.g., in the Y direction). That is, the dispersive element disperses the wavelength components of the detected light onto a first detector axis and the incidence / azimuth components of the detected light onto a second detector axis (e.g., orthogonal to the first axis). In a specific embodiment, the dispersive element includes a cylinder having a length proportional to a numerical aperture (NA) and configured to focus the point focus onto a line, and a dispersive element that disperses the light into a spectrum. The NA is related to the collected incidence / azimuth angle.

[0063] The detector may include any suitable detection mechanism for detecting light dispersed in two directions, such as a CCD for sensing light at a range of wavelengths, angles of incidence, and azimuth angles, as described herein. The detector may include any suitable number of shift registers for shifting data from selected pixels. For example, the detector may include two shift registers for parallel processing of light emitted from the sample at two different angles of incidence. In another embodiment, the detector includes more than two shift registers to allow parallel processing of light reflected from the sample at more than two different angles of incidence. In yet another embodiment, the detector includes only one row of pixels per shift register for angle of incidence detection to allow for fast readout.

[0064] The system 200 may also include a controller 230 configured to control any of the components of the system 200. For example, the controller 230 may be configured to select the angular frequency and / or azimuth angle and timing of one or more of the wavelengths of the light source 106, the polarizer 110, the illumination compensator 112, the analyzer 122, and the collection compensator. The controller 230 may also be configured to receive signals or image data generated by the detectors and analyze the resulting signals or images to characterize the sample by determining sample parameters, or to determine whether defects are present in the sample, or to characterize defects present in the sample. The system 200 may also include a positioning mechanism 231 to rotate, tilt, and / or translate various movable components (such as the sample stage, fixed aperture / mask, shutter, polarizer, analyzer, compensator, etc.) to various positions.

[0065] In certain embodiments, the detected light can be converted into digital data corresponding to different angles of incidence, azimuth angles, and wavelengths, which can be analyzed independently as a function of the angles of incidence, azimuth angles, and wavelengths (in addition to the polarization state). The data corresponding to the detected light can be split to correspond to different regions of the detector corresponding to different angles of incidence / azimuth angles and / or wavelengths. The split data can then be analyzed as a function of the angles of incidence, azimuth angles, and wavelengths (in addition to the polarization state). In certain embodiments, the optical signals from different angles of incidence can be acquired and processed simultaneously to improve measurement throughput. Increasing the illumination NA can reduce the diffraction-limited spot size at the target area of ​​the sample, thereby reducing the target size. Alternatively, even if the target size is not reduced, this increased NA increases the ratio of the detected light coming from within the target area to the light coming from the surrounding area, reducing signal contamination.

[0066] 3A is a simplified diagram of an example of an SE tool 300 for simultaneously collecting multiple incidence angle regions with multiple detectors according to certain embodiments of the present invention. As shown, the tool 300 includes a light source 106 providing multiple wavelengths of light, and an ellipsometer illumination optics 302 for imparting different polarization states to an illumination beam directed at the sample 132. The ellipsometer illumination optics 302 may also be configured to direct the illumination beam at multiple incidence angles and may be configured to direct light at multiple azimuthal angles. The tool 300 may also include an ellipsometer collection optics 304 for collecting light at multiple incidence angles (and azimuthal angles) and multiple polarization states. The light source 106, the ellipsometer illumination optics 302, and the ellipsometer collection optics 304 may correspond to any of the various illumination and collection components described herein.

[0067] The collection side of the tool 300 may also include a wavelength and incidence angle dispersion optic 306 that disperses the collected light in two mutually orthogonal directions according to wavelength and incidence angle. As shown, the dispersion result 309 at plane 1 (308) is illustrated. In this figure, three different incidence angle regions 1, 2, 3 are included for a first vertical axis, and the wavelength is dispersed over the entire incidence angle region for a second horizontal axis. Of course, any suitable number of incidence angle regions may be defined by the dispersion optic 306. The dispersion optic 306 may be configured to have different optical powers (e.g., cylindrical power, annular power, etc.) to disperse the incidence angle (and / or azimuth angle) and wavelength in two different directions, as described herein.

[0068] The tool 300 may also include a subdivision optics 310 that divides the beam dispersed in incidence angle (or azimuth) by the dispersion optics 306 into various incidence angle regions. The incidence angle subdivision optics may also be configured to direct each incidence angle region to an individual detector (e.g., 314a, 314b, 314c) that determines the wavelength and integrates over a range of incidence angles (or azimuth angles). If the incidence angle (or azimuth angle) and wavelength resolved planes are not sufficiently spatially separated, re-imaging optics 312 may be placed between these planes to re-image the wavelength resolved planes onto each detector. Each detector may be configured to detect over wavelengths from 190 nm to about 900 nm. Also, all detectors may be configured to read out simultaneously. The optics 306, 310, 312 and detector 314 may also be configured to collect and / or detect wavelengths in the range of 150 nm to 2000 nm. For example, a Si-based detector may be used for wavelengths less than about 1000 nm, and an InGaAs-based detector may be used for wavelengths greater than about 800 nm. Such an embodiment of the SE allows optical signals from different angles of incidence / azimuth to be acquired and processed simultaneously.

[0069] System 300 may also include a controller 330 configured to control the various components and analyze the detected data. Controller 330 may be, for example, similar to controller 230 of FIG. 2. Controller 330 may further be configured to control multiple detectors and analyze images and signals obtained by each such detector. System 300 may also include a positioning mechanism 331 for translating, rotating, or tilting any movable components. This positioning mechanism is similar to the positioning mechanism of FIG. 2, but allows for additional selection of positions for multiple detectors.

[0070] An alternative multiple incidence angle system may include apertures for selected incidence angles in a single detector. FIG. 3B is a simplified diagram of a second example of an SE tool 350 with a configurable incidence angle mask 351 to select an incidence angle range among multiple incidence angles according to another specific embodiment of the present invention. As shown, the wavelength-incidence angle (and / or azimuth) dispersion optics 348 is still configured to disperse the incidence angle (or azimuth) and wavelength in two different directions (e.g., orthogonal directions), but disperses the wavelengths in a plane located before the incidence angle / azimuth dispersion plane. That is, the incidence angle dispersion optics 348 of FIG. 3B may operate similarly to the incidence angle dispersion optics described with reference to FIG. 3A, but does not disperse the wavelengths in the same plane as the incidence angle / azimuth dispersion plane.

[0071] An incidence angle mask 351 may be placed on a plane on which the incidence angles are dispersed by a dispersion optics 348. The incidence angle mask may be configured to selectively send different incidence angle regions to the detector 352. For example, the incidence angle mask 351 provides a mechanism for selecting incidence angle / azimuth regions of the sample one at a time. View 354 shows an example of selecting incidence angle regions. In this view 354, incidence angle region 2 is selected and sent to the detector 352 through an aperture in the incidence angle mask 351, while incidence angle regions 1 and 3 are blocked by a mask portion of the incidence angle mask 351 (which is opaque and does not transmit light).

[0072] The incidence angle mask 351 may take any suitable form to allow for the selection of particular incidence angle regions. For example, the incidence angle mask 351 (or aperture) may comprise multiple fixed apertures, each with a shutter for selecting a different incidence angle region, or may comprise a single movable aperture (as shown). In embodiments using multiple fixed apertures, the apertures may be spatially separated to allow for resolution of different incidence angle regions of the sample, as described further herein.

[0073] The detector 352 (and 314) may take any suitable form for detection (in wavelength) along at least one direction, such as a two-dimensional detector or a one-dimensional linear photodiode array as described above. The detector 352 (and 314) is preferably located in the wavelength-resolving plane. The detector 352 may comprise a mask 351 defined by the width of the photosensitive area or by a mask integrated in the detector device. In this case, the dispersion optics 348 disperses the wavelengths in the same plane as the dispersion plane of the incidence angle / azimuth angle. Also in this case, the detector 352 is moved in the same way as the mask 351 to select the incidence angle region.

[0074] System 350 may also include a controller 360 and a positioning mechanism 361. This system may be configured with similar functionality to any of the controllers and / or positioning mechanisms described herein, but may also control or move the incidence angle mask 351 and / or detector 352.

[0075] For SE metrology tools (such as the systems of Figures 1, 2, and 3A) that illuminate a sample at multiple incidence angles and selectively collect (i.e., collect to separate detectors) one at a time without moving the illumination and collection optical paths, fixed illumination and collection pupils and fixed illumination and collection field stops allow for more repeatable and stable measurements than systems where the pupil and field stop change for each incidence angle measurement. System embodiments with movable field stops (such as the system of Figure 3B) require less aperture movement and can achieve faster throughput than systems with a moving aperture near the collection mirror, but at the cost of instability compared to systems without a moving aperture. All embodiments with optics with a fixed imaging path have a throughput advantage over systems that resolve incidence angles by moving imaging optics.

[0076] In another embodiment, multiple incidence angle regions can be collected simultaneously using a single two-dimensional detector. FIG. 3C illustrates the simultaneous collection of multiple incidence angle / azimuth angle regions on a single detector 370 according to an alternative embodiment. In this embodiment, the detector is divided into multiple incidence angle regions (e.g., 372a, 372b, 372c) that correspond to spatially separated incidence angle regions. These regions can be detected simultaneously and then analyzed separately. The incidence angle regions of the detector can be spatially separated by optically inactive regions (e.g., 374a, 374b). These inactive regions correspond to optically inactive pixel or signal portions that are not analyzed.

[0077] In any of the dispersion embodiments, both the incidence angle and the azimuth angle can be dispersed simultaneously by using a beam splitter to send the beam to two 2D detectors, one configured to disperse wavelength and incidence angle, and the other configured to disperse wavelength and azimuth angle. FIG. 3D illustrates a collection optics 380 for simultaneously collecting the dispersed incidence angle and azimuth angle according to one embodiment. As shown, an ellipsometer collection optics 382 can collect light from the sample at multiple incidence angles and multiple azimuth angles and direct the output to a splitter 384, which directs the output light to a wavelength-incidence angle dispersion optics 386 and a wavelength-azimuth angle optics 380.

[0078] The incidence angle dispersion optics 386 is configured to disperse the wavelengths and incidence angles along two directions in the same or different planes. The dispersed wavelengths and incidence angles are received by a wavelength and incidence angle detector module 388, which may be configured to simultaneously or sequentially detect spatially separated incidence angle regions (each having a dispersed wavelength, as described above). Similarly, the dispersed wavelengths and azimuth angles may be received by a wavelength and azimuth angle detector module 390, which may be configured to simultaneously or sequentially detect spatially separated azimuth angle regions (each having a dispersed wavelength).

[0079] FIG. 4A illustrates a configurable SE tool 400 with single or multiple apodizers 409 and / or 405 according to another embodiment of the present invention. In one arrangement, a single stationary apodizer 409 is placed at or near the illumination pupil. The apodizer is configured to shape the illumination beam and control the point spread function of the focal spot that is focused on the sample 132 for all selected angles of incidence (or azimuth angles). In another arrangement, one or more movable apodizers 409 may be moved in and out of the illumination pupil (e.g., in direction 410). The apodizer is typically configured to shape the illumination beam and control the point spread function of the focal spot that is focused on the sample 132 for various selected angles of incidence (or azimuth angles). For example, each selected apodizer may be configured to control the spot diameter for a particular set of angles of incidence (or azimuth angles). In a specific embodiment, each apodizer is configured such that the irradiance level at spot locations more than 25 microns away from the spot center is 10% of the peak irradiance at the spot center. -3 Each selected apodizer may be configured to shape the illumination light at a particular angle of incidence so that the azimuth angle is less than 0.05 mm. For example, each selected apodizer may be configured to reduce contamination of the measured signal at the particular selected angle of incidence (or azimuth angle) by suppressing side lobes and improving the measurement box size in the plane of the sample wafer.

[0080] In another embodiment, one or more collection apodizers 405 may be located at or near a plane conjugate to the collection pupil, or may be movable to that location. Such a collection apodizer may be used to provide a predefined collection profile for all of a discrete range of incidence and / or azimuth angles. The collection apodizer may control diffraction side lobes caused by a sharp collection aperture. For example, the collection apodizer may be configured to shape the intensity distribution incident on the spectrometer slit in a similar manner to how the illumination apodizer shapes the intensity distribution at the sample wafer. The collection apodizer could also be configured to reduce contamination from outside the measurement box and provide finer control of the spot at the spectrometer.

[0081] In the illustrated embodiment, different collection apertures are used to collect different angles of incidence, so that the spot at the slit is different depending on the angle of incidence, while the slit is the same for each range of angles of incidence. In this configuration, a collection apodizer configured for the particular angle of incidence to be used can be useful to adjust the spot for the particular angle of incidence. The collection apodizer is preferably located at or near the plane of the collection aperture, although it is contemplated that the apodizer could be located at a later stage. In a specific implementation, the number of apodizers corresponds to the number of collection apertures, and the selected apodizer can be moved into the collection path (e.g., in direction 411). Alternatively, a single dynamically configurable apodizer can be used and placed in the collection path.

[0082] Apodization can be generally defined as transforming the light distribution at the entrance pupil of an optical system (e.g., using a mask to change the amplitude and / or phase of the illumination beam), thereby changing the intensity profile of the illumination beam. In the present case, each apodizer reduces the irradiance in the "tails" of the illumination spot (e.g., the portion of the illumination spot that is greater than 25 microns from the center of the illumination spot) by 10% of the peak irradiance. -3 to less than 100 nm, thereby reducing signal contamination. The inclusion of such an apodizer in any of the measurement systems described herein is a feature that may enable measurements to be made using smaller spot diameters on smaller targets.

[0083] Transmissive apodizers (such as fused silica) can work for wavelengths up to about 170 nm. Typically, apodizers can be fabricated using standard lithographic reticle / mask blanks, which are optimized for 193 nm. Reflective apodizers are considered similar.

[0084] In general, each apodizer may be designed to be tailored for a particular set of selectable illumination side incidence angles (or azimuth angles), and each apodizer may be moved into the illumination beam path to control the spot size for each particular set of incidence angles (or azimuth angles). That is, each of these apodizer embodiments has a non-reconfigurable optical function. Additionally, a set of apodizers 409 may include apodizers configured for a particular test object. For example, different illumination amplitude profiles may be obtained for the same incidence angle. In addition to the system of FIG. 4A, any of the system embodiments described herein may include a configurable apodizer as well.

[0085] The system 400 of FIG. 4A may be arranged to include a scanning mirror (e.g., scanning mirror 407) to scan the illumination beam irradiated onto the sample 132 with different angles of incidence. The scanning mirror is preferably in or near a plane conjugate to the sample 132. The scanning mirror 407 may replace the polarizer slit, or may be conjugate to the polarizer slit. If the scanning mirror replaces the polarizer slit, the scanning mirror may include a mask that defines the illumination field stop. If the scanning mirror is conjugate to the polarizer slit, there may be another imaging optic between the polarizer slit and the scanning mirror. The scanning mirror 407 may replace a movable fixed aperture (e.g., as described above) to selectively scan the illumination beam with different angles of incidence (or azimuth angles). The scanning mirror 407 may be configured to be movable by any suitable positioning mechanism to select the specific angles of incidence (or azimuth angles) one by one. In the illustrated embodiment, scanning mirror 407 is tilted in direction 408 to scan the illumination beam through a range of incidence angles (or azimuth angles), i.e., scanning mirror 407 moves the illumination along different incidence angle positions in the pupil plane without moving the illumination spot at sample 132.

[0086] The scanning mirror 407 is reflective so that it operates over a wide range of wavelengths. By using a reflective scanning mirror 407, a wide range of wavelengths can be included in the illumination beam (including VUV light, which requires reflective optics).

[0087] A fixed mirror 406 may be used to direct the scanned illumination beam after it is reflected from a scanning mirror 407. Alternatively, multiple mirrors may be used to direct different angles of incidence onto the sample 132.

[0088] The illumination optics 402 may be configured to best direct illumination light of various angles of incidence (or azimuth angles) to the sample 132. For example, mirrors 414, 416 direct illumination beams from a particular set of angles of incidence (or azimuth angles) to focus on the sample 132. In one embodiment, mirrors 414, 416 are sized to direct all light between 50° and 80° to the sample 132.

[0089] As with other embodiments, a fixed or movable aperture 126 and / or shutter arrangement may be used to selectively collect light at different angles of incidence (or azimuth angles). The aperture / shutter 126 may be configured to select angles of incidence one at a time, as desired.

[0090] The illumination optics 402 and collection optics 404 may include components that generate and / or collect various polarization states (eg, polarizer 110, compensators 112 and 120, and analyzer 122).

[0091] The controller 430 and / or the positioning mechanism 461 may be configured to control any component of the system 400. For example, the controller 430 and / or the positioning mechanism 461 may be configured to select the wavelength of one or more of the light sources 106, the tilt position of the scan mirror 407 in the direction 408, the angular frequency and / or azimuth angle and timing of the polarizer 110, the illumination compensator 112, the collection compensator 120 and the analyzer 122, the position of each apodizer 409, the settings of the illumination and / or collection shutters, the position of the movable aperture, etc.

[0092] In most of the embodiments described herein, an amplitude apodizer can be used in the illumination path to suppress side lobes and improve the measurement box size in the wafer plane, reducing contamination of the measured signal. Although a single configurable apodizer or a set of movable apodizers can provide the appropriate amplitude apodization for a particular set of incidence angles (or azimuth angles), changing the apodizer pattern can be difficult in such an apodizer system. Furthermore, this arrangement can be associated with challenges of slow switching and hardware repeatability. In an alternative apodization embodiment, a dynamically configurable spatial light modulator (SLM) may be used to dynamically shape the apodizer pattern as needed. A variable apodizer (e.g., with MEMS SLM technology) can be switched very quickly without affecting the alignment of the system.

[0093] 4B illustrates a configurable SE tool 450 with a dynamically adjustable apodizer according to an alternative embodiment of the present invention. The system includes a dynamically configurable reflective apodizer 456 in the illumination path that is dynamically patterned for apodizing for each particular angle of incidence, azimuth, and NA selected for the illumination and collection optics. The apodizer 456 is preferably reflective to operate over a wide range from VUV to UV. As shown, the apodizer 456 may be positioned to receive illumination 452 from a rotating compensator 454 via an illumination slit 458.

[0094] As described above, a particular angle of incidence (and azimuth) may be selected using various illumination mechanisms, and a particular angle of incidence (and azimuth) may be collected using various collection mechanisms. The apodizer 456 is configured to dynamically adjust the amplitude and / or phase of the illumination light based on the angle of incidence (and azimuth) selected at the illumination and collection optics. In certain embodiments, the illumination beam may pass through a scanning mirror, or one or more fixed or movable apertures, or shutters, or a combination thereof, which are configured to select one or more spatially separated angles of incidence (azimuth) before reaching the apodizer 456. Alternatively, the apodizer 456 is placed before such an angle of incidence (or azimuth) selection mechanism. The apodizer 456 is preferably placed at or near the pupil plane. Alternatively, the apodizer 456 may be placed at or near the collection pupil. Alternatively, the apodizer 456 may be placed at or near both the illumination and collection pupils. The collection apodizer configuration can be used to control, for example, the spot shape at the detector slit. This type of apodization may reduce contamination from outside the box upon receipt at the detector, and may also improve the resolution (or PSF) of the detector. Additionally or alternatively, different angles of incidence (or azimuth angles) may be collected, such as by fixed or movable apertures and / or shutters.

[0095] In a specific embodiment, apodizer 456 comprises a spatial light modulator (SLM) that can be configured to control the amplitude reflectance distribution over the full range of apodizer 456. One suitable SLM is a micro-electro-mechanical system (MEMS) based SLM. Exemplary SLM type devices include DLP (Digital Light Processing®) devices available from Texas Instruments, Inc. (Dallas), and TX and SLM devices from the Fraunhofer Institute (Munich, Germany).

[0096] As with DLP devices, the apodization pattern may be a binary amplitude pattern, integrated over multiple pixels to obtain an effective (continuous) reflection pattern. The percentage of pixels in a local area that reflect light back to the illumination optics provides the desired level of local apodization. A spatial filtering aperture may be used after the DLP SLM to block light reflected away from the illumination optics and to filter out diffraction due to the periodic structure of the DLP SLM. This aperture may also be incorporated into the aperture of the focusing optic itself.

[0097] In another SLM embodiment, the apodizing pattern may be continuously variable. However, a continuously variable amplitude distribution may be achieved by encoding a pattern in the phase distribution generated by the SLM. To achieve the desired resulting amplitude pattern, the light must be Fourier filtered with an aperture, which may be incorporated into the focusing optics of the system.

[0098] System 450 may also include controls and / or positioning mechanisms (not shown) similar to any of the controls and / or positioning mechanisms described above, but further including control of apodizer 456.

[0099] In certain embodiments described herein, a fixed or movable aperture may be used to select a particular angle of incidence (or azimuth) for the illumination beam directed toward or collected from the sample. FIG. 5A is a side view of an exemplary aperture system 500 according to one implementation. As shown, the aperture system 500 may include a reflective substrate 502 on which a mask is formed. The mask is comprised of absorbing or non-reflective regions (e.g., 504a, 504b, 504c) with holes / vias (e.g., 506a, 506b, 506c) formed therein. Exemplary absorbing or non-reflective materials include metal sheet or foil materials (e.g., stainless steel or aluminum) and black anodized aluminum materials. The holes may be filled with a transparent material or may be left unfilled. A shutter (e.g., 508a, 508b, 508c) may be positioned or attached to cover each mask aperture (e.g., 506a, 506b, 506c). The entire aperture system 500 may also be movable (e.g., in direction 514) to allow the apertures to be positioned within the illumination or collection paths as described further herein.

[0100] These shutters may be opened or closed to reflect incident light at particular angles of incidence (or azimuth). As shown, for bundle of rays 510b, shutter 508b is closed while shutters 508a and 508c are open. In this manner, ray 510a is reflected off of reflective substrate 502 as ray 512a at a first selected angle of incidence (or azimuth), and ray 510c is reflected off of reflective substrate 502 as ray 512c at a second selected angle of incidence (or azimuth).

[0101] 5B is a side view of an exemplary aperture system 550 according to a second embodiment. As shown, the aperture system 550 may include a reflective substrate 552. The aperture system 550 does not include a shutter and is movable along a direction 564 to allow positioning of fixed apertures (e.g., 554a, 554b, 554c). The apertures are formed in an absorbing or non-reflective masking material (e.g., 556a, 556b, 556c). The apertures may be positioned at specific angles of incidence (or azimuth angles) in the illumination or collection path. As shown, at a first selected angle of incidence, ray 560a is reflected as ray 562a, at a second selected angle of incidence, ray 560b is reflected as ray 562b, and at a third selected angle of incidence, ray 560c is reflected as ray 562c.

[0102] Any embodiment of the system may include a transmissive illumination selector that selectively applies apertures to each of a number of pupil locations, allowing a specific set of incidence angles (or azimuth angles) to be selected as described herein. However, the illumination selector may only be applied to the transmittable wavelengths, not the reflection. In general, the illumination selector is configured to allow the light beams to pass through each pupil location individually to obtain a distinct range of incidence / azimuth angles. FIG. 6A is a perspective view of an illumination selector according to an embodiment of the invention. In this example, the illumination selector is configured with three aperture disks 602, 604, and 606. Each aperture disk includes a number of different aperture configurations (e.g., aperture configurations 608a, 608b on disk 602, aperture configuration 610a on disk 604, and aperture configurations 612a, 612b, and 612c on disk 606). A specific aperture configuration is selected for each disk to receive the incident beam (or ray bundle) 614, and then the three selected aperture configurations from the three disks can be then superimposed, resulting in a different number of aperture settings and, consequently, a different number of illumination pupil profiles.

[0103] In general, each of the aperture configurations of each disk includes at least one transparent portion and may also include one or more opaque regions. For example, the transparent portions may be formed from any suitable transparent material (glass, crystal, fused quartz, etc.). Alternatively, each transparent region may simply lack material such that light passes through each transparent portion of the aperture configuration. In contrast, each opaque portion blocks a corresponding spatial portion of the incident beam at the pupil plane. Each opaque portion is typically formed from an opaque material, such as chromium, molybdenum silicide (MoSi), tantalum silicide, tungsten silicide, or opaque MoSi on glass (OMOG). A polysilicon film may be added between the opaque layer and the transparent substrate to improve adhesion. A low-reflection film may be formed on the opaque material. Such low-reflection films include molybdenum oxide (MoO2), tungsten oxide (WO2), titanium oxide (TiO2), or chromium oxide (CrO2). The transparent portion of each aperture may have any suitable shape. For example, there are rectangles, circles, ellipses, LHC screens (superimposed circle and rectangle), marguerites (two LHC screens with one rotated by 90°), rectellipse (superimposed ellipse and rectangle), and racetrack shapes.

[0104] Typically, an aperture configuration is used to create a specific incident beam profile or a specific set of incident and azimuth angles. In a specific embodiment, Source Mask Optimization (SMO) or any pixelated illumination technique may be implemented. In the illustrated embodiment, each aperture configuration covers the entire illumination pupil area and is located at the center of the optical axis. However, alternatively, the aperture configuration may be located in a portion of the pupil area or at other points (not in the pupil plane) along the optical path of the incident beam.

[0105] FIG. 6B illustrates the combination of three aperture configurations to obtain a second embodiment of an aperture configuration. For simplicity, the size of the transparent portions has been exaggerated. In this embodiment, the first aperture configuration 610a is completely transparent over the entire pupil area. The second aperture configuration 608b has a transmissive vertical transparent strip 652 surrounded by opaque portions 654, 656. The third aperture configuration 612b has a horizontal transparent strip 622 surrounded by opaque portions 624, 620. The resulting aperture configuration 630 has a square transparent portion 634 surrounded by opaque portions 632, which can be configured to select a particular set of angles of incidence.

[0106] 7A illustrates a configurable metrology tool 700 with an off-axis parabolic (OAP) mirror according to another embodiment of the present invention. The system 700 includes an off-axis parabolic (OAP) mirror 710a at the illumination side 702 that is used in conjunction with a translatable mirror 712 to select multiple angles of incidence (e.g., from an illumination beam received from a reflecting mirror 722a) and move the mirror 712 from, for example, position 712a to position 712b. Typically, for example, the movable illumination mirror 712 can be shifted along a direction (e.g., 714a) to reflect the illumination beam from the illumination OAP 710a to obtain a particular set of angles of incidence based on the position on the curve of the OAP from which the illumination beam is reflected. In the illustrated embodiment, two different illumination translation mirror positions 712a, 712b are shown to obtain two different spatially separated angles of incidence on the sample 132, one after the other, although more mirror positions (configured to reflect the illumination beam from different regions of the OAP curve) may be used to obtain more angles of incidence.

[0107] The collection optics 704 of the system 700 may include, for example, a corresponding collection OAP mirror 710b positioned to collect the output beams from the sample 132 at a selected angle of incidence, and a similar collection translation mirror 713 configurable to move to a number of positions (e.g., 713a, 713b) in a direction 714b to receive these output beams one-by-one from the collection OAP 710b at the selected angle of incidence. The collection optics 704 may also include any suitable optical elements (e.g., a convex mirror 720 and a reflective mirror 722b) to direct the output beams (e.g., a collimated beam 716) to the detector 124.

[0108] In another aspect, the translating mirrors (712 and 713) and the OAP mirrors (710a and 710b) may be configured to accommodate a wide range of incidence angles (up to near grazing incidence), i.e., the translating mirrors and the OAP mirrors may be configured to select incidence angles over a continuous range.

[0109] The controller 730 and / or the positioning mechanism 761 may be configured to control any component of the system 700. For example, the controller 730 and / or the positioning mechanism 761 may be configured to select the wavelength of one or more of the light source 106, the angular frequency and / or azimuth angle and timing of the polarizer 110, the illumination compensator 112, the analyzer 122 and the collection compensator 120, the translation of each of the translating mirrors 712, 713, the rotation of the OAP mirror, etc.

[0110] In another embodiment, FIG. 7B illustrates a dual-pass metrology tool 750 with an off-axis parabolic (OAP) mirror according to an alternative embodiment of the present invention. The system 750 includes an off-axis parabolic (OAP) mirror 760 used in conjunction with a translatable mirror 762 to select multiple angles of incidence (e.g., from the illumination beam received from the beam splitter 752) and move the mirror 762 from position 762a to 762b. Typically, for example, the movable illumination mirror 762 can be shifted along a direction (e.g., 764) to reflect the illumination beam from the illumination OAP 760 to a particular set of angles of incidence based on the position on the curve of the OAP from which the illumination beam is reflected. This movement causes the output beam from the sample 132 to change position at the spherical mirror 754 before reflecting off the spherical surface 754 and returning to the extraction position. A second output beam exits sample 132 in response to the beam returning from spherical mirror 754 and the target property after scanning the sample as described above. The second output beam is then collected by OAP mirror 760, translating mirror at position 762a or position 762b and beam splitter 752 and directed to a detector (not shown).

[0111] In another embodiment shown in FIG. 7B, a positioning mechanism 791 along with a controller 780 may be used to tip / tilt the sample 132 or the surface under test around the measurement point 756. For example, continuous or sequential scanning of the incidence angle and azimuth angle can be achieved by tipping / tilting the sample via the positioning mechanism 791. This movement causes the output beam from the sample 132 to change position on the spherical mirror 754 before reflecting off the spherical mirror 754 and returning to the extraction position. A second output beam exits the sample 132 in response to the beam returning from the spherical mirror 754 and the target characteristic after scanning the sample as described above. The second output beam is then collected by the OAP mirror 760, mirror 762 (which is fixed in this embodiment) and beam splitter 752 and directed to a detector (not shown). In this embodiment, the position of the translation mirror 762 is kept fixed while the wafer is tilted.

[0112] The embodiments of the multi-incidence and multi-azimuth angle systems described herein may also be configured such that the collector side extracts the zeroth order light reflected by the sample for bright-field operation, or the collector arm extracts the non-zero order light reflected by the sample for dark-field operation. In one arrangement, a set of spatially separated illumination apertures and another set of spatially separated collection apertures are arranged to allow selection between bright-field and dark-field operation. In bright-field operation, the collector side extracts the same angle of incidence (azimuth) of the illumination light reflected by the sample. In dark-field operation, the collector side extracts a different angle of incidence (azimuth) of the illumination light reflected by the sample.

[0113] In any of these multiple incidence angle (or azimuthal angle) systems, the illumination optics can be configured to generate multiple illumination beams separated in the azimuth direction of the wafer (e.g., covering 0° to 90° simultaneously). The system can include a set of spatially separated detectors capable of receiving separate light beams, with the illumination optics and collection optics supporting multiple incidence and azimuthal angles for each beam.

[0114] Any suitable measurement process may be implemented with the systems described herein. FIG. 8 is a flow chart illustrating an SE metrology procedure 800 according to one embodiment of the present invention. To begin, multi-wavelength (e.g., VUV to IR) illumination may be generated in step 802. In step 804, one or more polarization states may be selected for the illumination. In step 806, one or more ranges of incidence angles and / or azimuth angles may also be selected for the illumination. In step 808, as one example, the illumination may be further shaped and steered to form a small spot on a target on a wafer.

[0115] In step 810, an output beam may then be collected that exits the wafer in response to the illumination beam. In step 812, one or more angles of incidence or azimuth may be further selected for collecting the output beam. In step 814, one or more polarization states may also be selected. In step 816, the output beam may then be detected and used to generate a signal or image. In step 818, the generated signal or image may then be analyzed to determine characteristics of the object on the wafer. For example, for various object characteristics, the corresponding object characteristics are determined by comparing the signals / images output from the model after simulation with the generated signals / images for various illumination characteristics (e.g., polarization states, wavelengths, angles of incidence, and azimuth angles).

[0116] Exemplary sample parameters that may be determined based on one or more detected signals or images include critical dimension (CD), film thickness, metal gate recess, high-k recess, sidewall angle, step, pitch walking, trench and contact profile, overlay, material properties, semiconductor manufacturing process parameters (e.g., focus and dose of a scanner, etch rate of an etching tool), material composition, refractive index, stress on critical films (including ultra-thin diffusion layers, ultra-thin gate oxides, advanced photoresists, 193 nm ARC layers, ultra-thin multi-layer stacks, CVD layers, and advanced high-k metal gates (HKMGs)), ultra-thin decoupled plasma nitridation (DPN) process layers, and stress on non-critical films (including intermediate insulators, photoresists, bottom anti-reflective coatings, thick oxides and nitrides, and back end of line (BEOL) layers).

[0117] Although the above invention has been described in some detail for ease of understanding, it will be apparent that certain changes and modifications may be made within the scope of the appended claims. It should be noted that there are many alternatives to the process, system, and apparatus of the present invention. For example, while an embodiment of a system applicable to metrology of semiconductor devices is described herein, it is believed that such a system may be utilized in other types of applications, such as metrology or defect inspection of other types of specimens. Thus, the present embodiments should be considered as illustrative and not restrictive, and the invention is not limited to the details set forth herein.

Claims

1. An ellipsometer apparatus for measuring a semiconductor sample, comprising: an illumination optics module for providing an illumination beam at a plurality of selectable wavelengths ranging from vacuum ultraviolet (VUV) to infrared (IR) wavelengths and directing the illumination beam at a plurality of angles of incidence (AOI) and azimuthal angles (AZ) towards the semiconductor sample; a collection optics module that collects output beams emerging from the semiconductor sample in response to the illumination beam impinging on the semiconductor sample at substantially all of the angles of incidence and azimuthal angles and directs the output beams to a plurality of detectors substantially simultaneously; the illumination optics module includes a polarization generating optical element that generates a plurality of polarization states for the illumination beam, and the collection optics module includes a polarimetric optical element that analyzes the polarization states of the output beam; the illumination optical module and the collection optical module each include a reflective optical element between the polarization generating optical element that generates the plurality of polarization states and the polarization analyzing optical element that analyzes the plurality of polarization states; a plurality of detectors that receive and detect the output beam from the semiconductor sample at the angles of incidence and azimuth and at the polarization state, and generate a plurality of signals or images based on the output beam at the angles of incidence and azimuth and at the polarization state; one or more controls configured to control, respectively, selecting a wavelength range, selecting the polarization state, and analyzing the signal or image at the wavelength, angle of incidence and azimuth, and the selected polarization state to determine a characteristic of the semiconductor sample; the collection optics module includes one or more dispersive elements for dispersing the wavelengths in a wavelength plane and dispersing the incidence angles and azimuth angles in an incidence angle / azimuth angle plane, the wavelengths and the incidence angles and azimuth angles being dispersed along two different detection directions, the two different detection directions being in two mutually orthogonal axial directions, one axis corresponding to the wavelength and the other axis corresponding to the incidence angle or azimuth angle; a partial division optical system that divides the beam dispersed by the dispersion element into a plurality of incident angle regions or azimuth angle regions; a re-imaging optical system that re-images the wavelength plane onto each of the plurality of detectors for each of the plurality of incident angle regions or azimuthal angle regions, each detector of the plurality of detectors is configured to determine the dispersed wavelengths and comprises a plurality of registers for simultaneously processing parallel data from a plurality of different incidence angle regions and a pixel for detecting the incidence angle regions, or a plurality of registers for simultaneously processing parallel data from a plurality of different azimuthal angle regions and a pixel for detecting the azimuthal angle regions; Ellipsometer instrument.

2. The apparatus of claim 1 , wherein the one or more dispersive elements have two different optical powers for the two different directions.

3. 2. The apparatus of claim 1, wherein the collection optics module includes an incidence angle / azimuth angle mask in a plane conjugate to a pupil for selectively transmitting a particular incidence angle region from a plurality of spatially separated incidence angle and azimuth angle regions in the output beam.

4. 4. The apparatus of claim 3, wherein the wavelength dispersion plane is located in front of the incidence angle / azimuth angle dispersion plane.

5. The apparatus of claim 3 , wherein the incidence / azimuth mask is comprised of a plurality of fixed apertures, each aperture having a shutter.

6. The apparatus of claim 3 , wherein the incidence / azimuth mask comprises a fixed movable aperture.

7. The apparatus of claim 1 , wherein the multiple detectors determine the dispersed wavelengths and integrate over different incidence angle ranges.

8. 2. The apparatus of claim 1 , wherein the collection optics module includes: a beam splitter that splits the output beam into a first output beam and a second output beam; a first dispersive element that receives the first output beam and disperses the wavelength and the incidence angle of the output beam along two different detection directions of a first detector of the plurality of detectors; and a second dispersive element that receives the second output beam and disperses the wavelength and the azimuth angle of the output beam along two different detection directions of a second detector of the plurality of detectors.

9. 2. The apparatus of claim 1, wherein the wavelength dispersion plane is coplanar with the incidence angle / azimuth angle dispersion plane.

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