Reflectometer, spectrophotometer, ellipsometer and polarimeter systems including wavelength modifiers

Abstract

Ellipsometer, polarimeter, reflectometer and spectrophotometer systems include one or more wavelength modifiers that convert the wavelength provided by the electromagnetic radiation source to a different wavelength for use in investigating a sample, and / or a wavelength that can be detected by its detector.

Description

[0001] This application claims the benefit of provisional applications 63 / 143,187 filed on January 29, 2021 and 63 / 259,830 filed on August 17, 2021. Technical Field

[0002] Ellipsometer, polarimeter, reflectometer and spectrophotometer systems include one or more wavelength modifiers that convert the wavelength provided by the electromagnetic radiation source to a different wavelength for investigating a sample and / or to a wavelength that can be detected by its detector. Background Art

[0003] The use of electromagnetic radiation to investigate samples is well known. For example, reflectometers, spectrophotometers, ellipsometers and polarimeter systems direct a beam of electromagnetic radiation to interact with a sample (in reflection and / or transmission) before the beam enters a detector. Detected changes in intensity (in reflectometer and spectrophotometer systems) and changes in polarization state (in ellipsometer and polarimeter systems) as a result of the interaction provide insight into the properties of the sample. Properties such as absorption constants, ellipsometric parameters Psi and Delta are typically evaluated by performing a mathematical regression of the accumulated data against a mathematical model of the sample.

[0004] Conventional practice is to provide an electromagnetic radiation source including a desired wavelength and guide its light beam so that it interacts with the sample, and then enter the detector. However, when the wavelength provided is, for example, within the range of IR or THz, detecting them requires a special detector system (for example, a high-laid box or a bolometer (bolimeter) etc.). The detector of IR and THz wavelengths is much more difficult to use than, for example, a solid-state detector suitable for detecting a visible range wavelength. The present invention recognizes this and provides a wavelength modifier, which, for example, receives IR or THz wavelengths and provides a visible range wavelength such as derived from IR and THz wavelengths. Further, it is possible to use an investigator who provides a system such as IR or THz wavelengths and may wish to easily expand the investigation to include, for example, visible wavelengths. In this case, a wavelength modifier can be applied before the sample. The example of the wavelength modifier currently available is produced by Danish company NLIR, and the wavelength modifier converts the wavelength of the MIR range to a near-visible wavelength. Therefore, a data sheet is provided in Information Disclosure (Information Disclosure).

[0005] The invention focuses on the use of wavelength modifiers in ellipsometer, polarimeter, reflectometer and spectrophotometer systems to obtain patent rights, while also having as ancillary interest subject matter such as electromagnetic radiation sources and detectors thereof. With regard to upconversion, wavelength modifiers apparently work by exploiting the properties of surface states in semiconductors. In a recent press release, Mona Jarrahi of the Department of Computer and Electrical Engineering at the University of California, Los Angeles (UCLA) reported that electrons in the semiconductor lattice experience an increase in energy when hit by incident light, allowing them to jump around in the lattice. Electric fields boost the energy even further. When the electrons release their energy through photon emission, their wavelengths are different.

[0006] Continuing, it is always beneficial to investigate a sample using multiple angles of incidence of the beam to the sample surface and at as many wavelengths as possible. Although no preferred source is identified herein (other than to determine a source compatible with the use of a wavelength modifier), the latter point can be addressed by using a source of electromagnetic radiation beams known as supercontinuum lasers. For more insight into supercontinuum sources, see Van Derslice's patent 11 / 035,729. Although the formation of a supercontinuum laser spectrum is the result of many complex nonlinear effects, for the purposes of the present invention, we do not need to be concerned with these, and the present invention does not depend on how the supercontinuum is generated, only that it is a supercontinuum and can be applied to, for example, a reflectometer, a spectrophotometer, an ellipsometer, or a polarimeter. Furthermore, the present invention focuses on the use of wavelength modifiers in such sample investigation systems.

[0007] A search for patents on the use of wavelength modifiers in ellipsometer, polarimeter, reflectometer and spectrophotometer systems yielded no results. However, the inventors have previously discovered and known patents in closely related fields of patent work, and therefore disclose them here. For example, the following are disclosed:

[0008] Knight et al. Patent No. 8,422,519;

[0009] Patent No. 8,718,104 to Clowes et al.

[0010] Published Application No. 2014 / 0233091 by Clowes et al.;

[0011] Patent No. 7,345,762 to Liphardt et al.;

[0012] LeVan's Patent No. 6,104,488.

[0013] Additional patent references identified in the computer search are:

[0014] Searching for "Supercontinuum Laser and Ellipsometer" yields five patents, with numbers 9,080,971, 8,873,054, 8,441,639, 8,031,337, and 7,570,358, and six published applications, with numbers 2015 / 0323316, 2015 / 0036142, 2013 / 0222795, 2011 / 0069312, 2009 / 0262366, and 2008 / 0239265; and

[0015] A search for "Supercontinuum & Laser and Ellipsometer and Speckle" provides no patents and only four published applications, with application numbers 2015 / 0058813, 2015 / 0046121, 2015 / 0046118 and 2015 / 0330770.

[0016] Also, known patents and published applications regarding speckle reduction are: 6,895,149 to Jacob et al.; 7,522,331 to Lapchuk et al.; US2013 / 0027673 to Moussa; US2006 / 0238743 to Lizotte et al.; and US2013 / 0010365 to Curtis.

[0017] Further, during the prosecution of patent application 14 / 757,280, the examiner identified:

[0018] US2012 / 0057158 by Hilfiker et al.;

[0019] US2013 / 0026368 by Herzinger;

[0020] US2013 / 0304408 by Pandev;

[0021] US2013 / 0268336 by Ostermeyer;

[0022] US2015 / 0219497 by Johs;

[0023] US2009 / 0267003 by Moriva et al.;

[0024] US2014 / 0304963 by Grejeda;

[0025] US2013 / 0063700 by Yamaguchi et al.

[0026] There is also known an article by Han et al., published in "Review of Scientific Instruments" Vol. 74, No. 6 in June 2003, entitled "A New Spectrometer Using Multiple Gratings With A Two-Dimensional Charge-Coupled Diode Array Detector", which describes a special grating composed of three laterally stacked sub-gratings to produce three wavelength ranges.

[0027] It should be understood that a wavelength modifier can be applied after the stage of the sample investigation system to change the wavelength provided by its source to a wavelength that can be detected by the detector after interaction with the sample. It should also be understood that a wavelength modifier can be placed before the stage of the sample investigation system to shift the wavelength used in the sample investigation. The latter effect can be used to extend the range of, for example, IR and THz systems into the visible light range.

[0028] Even in view of the known prior art, there remains a need for the benefits provided by the use of wavelength modifiers in ellipsometer, polarimeter, reflectometer and spectrophotometer sample investigation systems (either on the detector side of the system stage or on the source side thereof). Summary of the invention

[0029] First, it must be understood that, as in co-pending application Serial No. 16 / 602,088, the sample survey system of the present invention and the method of use can be composed of and derived from various combinations of at least three different sub-invention fields, which are:

[0030] Combined use of detector systems that can be optimized for various electromagnetic radiation wavelength ranges;

[0031] The use of a supercontinuum laser for providing a coherent beam of electromagnetic radiation in the wavelength range of at least 400-4400 nm, possibly in combination with other sources of electromagnetic radiation in an extended wavelength range; and

[0032] Application of a speckle reducer with a supercontinuum laser source to effectively provide a more consistent intensity versus position relationship in a beam of electromagnetic radiation derived from a supercontinuum laser output in systems such as ellipsometers, reflectometers, spectrophotometers, and the like.

[0033] However, the presently disclosed invention further includes inventions from additional sub-fields of invention, namely:

[0034] Most importantly, the use of wavelength modifiers that receive electromagnetic radiation of, for example, relatively longer wavelengths (e.g., in the infrared (IR) and terahertz (THZ) ranges) that cannot be detected by, for example, solid-state detector elements, and provide electromagnetic radiation of relatively shorter wavelengths that can be detected by, for example, solid-state (or other types of) detector elements;

[0035] Application of wavelength modifiers that receive relatively shorter wavelength electromagnetic radiation that cannot be detected by detectors such as Golay cells, bolometers, microbolometers, thermocouples, photoconductive materials, photoconductive materials, deuterated triglycine sulfate (DTGS), HgCdTe (MCT), LiTaO3, PbSe, PbS and InSb, and provide relatively longer wavelength electromagnetic radiation that can be detected by them.

[0036] Additional sub-invention fields are:

[0037] Provide the application of supercontinuum laser source with wavelength up to about 18000nm;

[0038] The use of additional types of electromagnetic radiation sources in combination with or in place of supercontinuum lasers to expand the wavelength range that can be used with the sample investigation system of the present invention (e.g., Nernst luminophores and carbon silicon rods and other sources can be provided with wavelengths up to 14,000 nm and 50,000 nm, respectively, or other possible sources, including DTHS; laser stabilized arc lamps, Hg arc lamps, fixed or tunable quantum cascade lasers, QTH and Xe lamps, laser stabilized arc lamps, other laser driven sources);

[0039] The use of supercontinuum lasers in Fourier transform infrared sources by combining supercontinuum lasers with Michelson interferometers, combined with other distinguishing factors, is believed not previously disclosed in the context of use in ellipsometer, reflectometer, spectrophotometer, etc. systems;

[0040] The described subclasses of the invention in various combinations are believed to provide new, novel and non-obvious sample survey systems and enable new, non-obvious and useful methods of use thereof.

[0041] In this application, the present invention focuses on a sample survey system selected from the group consisting of:

[0042] Ellipsometer;

[0043] Polarimeter;

[0044] Reflectometer; and

[0045] Spectrophotometer;

[0046] For use in investigating samples using electromagnetic radiation;

[0047] The system comprises:

[0048] Electromagnetic source (LS);

[0049] a stage (STG) for supporting a sample; and

[0050] A detector (PA) comprising detector elements (DE's).

[0051] In an important embodiment, the system source (LS) provides long wavelength electromagnetic radiation in the IR and THz range, and the detector comprises solid-state elements (DE's) that are not capable of detecting said IR and THz wavelengths. However, the system is characterized in that, before the detector (PA), there is at least one wavelength modifier (WM), which is used to accept electromagnetic radiation of a wavelength outside the range detectable by the detector elements (DE's) of the detector (PA) and based thereon provides output electromagnetic radiation of a wavelength detectable by the detector elements (DE's).

[0052] The system may further comprise a polarization state generator (PSG) and a polarization state analyzer (PSA) before and after the stage, respectively, and the system is an ellipsometer.

[0053] The system may provide that at least one wavelength modifier (WM) receives electromagnetic radiation comprising wavelengths in the IR and THz ranges and outputs electromagnetic radiation having a wavelength in the visible wavelength range.

[0054] The system may provide that at least one wavelength modifier (WM) receives electromagnetic radiation comprising wavelengths in the far IR range and outputs electromagnetic radiation having a wavelength in the visible wavelength range.

[0055] The system may provide that at least one wavelength modifier (WM) receives electromagnetic radiation comprising wavelengths in the mid-IR range and outputs electromagnetic radiation having a wavelength in the visible wavelength range.

[0056] The system may provide that at least one wavelength modifier (WM) receives electromagnetic radiation comprising wavelengths in the near IR range and outputs electromagnetic radiation having a wavelength in the visible wavelength range.

[0057] The system may further include dispersive optics between the stage and the detector for spatially separating different wavelengths for presentation to a multi-element (DE's) detector (PA).

[0058] The wavelength modifier can be placed in one of the following locations:

[0059] between the source (LS) and the stage (STG);

[0060] between the stage (STG) and the dispersive optical device;

[0061] between the dispersive optics and the detector (PA).

[0062] The present invention is also a sample survey system selected from the group consisting of:

[0063] Ellipsometer;

[0064] Polarimeter;

[0065] Reflectometer; and

[0066] Spectrophotometer;

[0067] For use in investigating samples using electromagnetic radiation;

[0068] The system comprises:

[0069] Electromagnetic source (LS);

[0070] a stage (STG) for supporting a sample; and

[0071] Detector (PA).

[0072] The system may provide a source (LS) providing electromagnetic radiation in a wavelength range that is longer or shorter than the detector elements (DE's) can detect; and the system may be characterized in that, before the detector (PA), there is at least one wavelength modifier (WM) for receiving electromagnetic radiation of a wavelength outside the range that the state elements (DE's) of the detector (PA) can detect and, based thereon, providing output electromagnetic radiation of a wavelength that the solid-state elements (DE's) can detect. The system may provide that the source (LS) provides electromagnetic radiation of a wavelength in a range selected from:

[0073] Ultraviolet light;

[0074] Visible light;

[0075] Far infrared;

[0076] Mid-infrared;

[0077] Terahertz waves;

[0078] and the detector detects a wavelength within a range selected from:

[0079] Ultraviolet light;

[0080] Visible light;

[0081] Far infrared;

[0082] Mid-infrared;

[0083] Terahertz waves;

[0084] Wherein said selected detected wavelength range is different from that provided by said source (LS).

[0085] The system may provide that the source provides a wavelength within a range selected from:

[0086] Far infrared;

[0087] Mid-infrared;

[0088] Near infrared; and

[0089] Terahertz waves;

[0090] And the wavelength modifier provides a wavelength within a range selected from the group consisting of:

[0091] Ultraviolet light; and

[0092] Visible light.

[0093] The present invention is also a method for investigating a sample, comprising the following steps:

[0094] a) Provide:

[0095] Ellipsometer;

[0096] Polarimeter;

[0097] Reflectometer; and

[0098] Spectrophotometer;

[0099] For use in investigating samples using electromagnetic radiation;

[0100] The system comprises:

[0101] Electromagnetic source (LS);

[0102] a stage (STG) for supporting a sample; and

[0103] a detector (PA) comprising detector elements (DE's);

[0104] The source (LS) of the system provides electromagnetic radiation within a wavelength range that is longer or shorter than the range that the detector elements (DE's) can detect; and the system is characterized in that, before the detector (PA), there is at least one wavelength modifier (WM), which is used to accept electromagnetic radiation of a wavelength outside the range that the solid-state elements (DE's) of the detector (PA) can detect, and based on this, provides output electromagnetic radiation of a wavelength that the solid-state elements (DE's) can detect.

[0105] The method continues:

[0106] b) placing the sample to be investigated on the stage (STG);

[0107] c) causing said source (LS) to provide electromagnetic radiation comprising a wavelength which said detector elements (DE's) cannot detect, and directing its beam to said sample;

[0108] d) causing said wavelength modifier to receive wavelengths of electromagnetic radiation from said sample provided by said source (LS) and to modify them to wavelengths detectable by said detector elements (DE's);

[0109] e) causing the detector element to detect the modified electromagnetic radiation and provide output data;

[0110] f) analyzing the output data to determine sample characteristics.

[0111] The method may provide that the system further comprises dispersive optics for spatially separating different electromagnetic wavelengths.

[0112] The wavelength modifier (WM) may be positioned between the source (LS) and the stage, or between the stage (STG) and the dispersive optics, or between the dispersive optics and the detector (PA).

[0113] Another method of investigating a sample using electromagnetic radiation of different wavelengths provided by an electromagnetic radiation source comprises the following steps:

[0114] a) Provide:

[0115] Ellipsometer;

[0116] Polarimeter;

[0117] Reflectometer; and

[0118] Spectrophotometer;

[0119] For use in investigating samples using electromagnetic radiation;

[0120] The system comprises:

[0121] Electromagnetic source (LS);

[0122] a stage (STG) for supporting a sample; and

[0123] a detector (PA) comprising detector elements (DE's);

[0124] The source (LS) of the system provides electromagnetic radiation in a wavelength range that is longer or shorter than what the detector elements (DE's) can detect;

[0125] The system is characterized in that before the stage (STG) there is a wavelength modifier (WM).

[0126] The method continues:

[0127] b) placing the sample to be investigated on the stage (STG);

[0128] c) causing said source (LS) to provide electromagnetic radiation and directing its beam towards said sample;

[0129] d) causing said wavelength modifier (WM) to receive wavelengths of electromagnetic radiation in a first range provided by said source (LS) thereof and to emit wavelengths in a modified range;

[0130] e) causing said detector elements (DE's) to detect the modified electromagnetic radiation wavelength after the modified electromagnetic radiation wavelength interacts with said sample (MS); and

[0131] f) analyzing the output data to determine sample characteristics.

[0132] The method may further comprise a step (c') between steps c) and d): placing a second wavelength modifier (WM) between the stage (STG) and the detector (PA) to place the wavelength from the sample (MS) within a range detectable by the detector elements (DE's) in the detector (PA).

[0133] In view of the main invention claimed herein (the use of a wavelength modifier (WM) to change the wavelength of electromagnetic radiation at various points within a sample investigation system), it should be understood that any source of electromagnetic radiation may be used with the present invention to provide electromagnetic radiation of the desired wavelength. For example, continuous spectrum sources (such as Ar, Xe and He discharge lamps in the UV region; and tungsten filament lamps in the visible light; and black body radiators, Nernst and carbon silicon rod sources in the infrared range) may be applied. Linear sources (such as Hg and Na lamps in the UV and visible ranges) may also be applied, as well as lasers in the visible and IR ranges. However, benefits may arise from the fact that the intensity of the electromagnetic radiation beam from a supercontinuum laser is generally much higher over a larger wavelength range than from other electromagnetic radiation sources conventionally used in ellipsometry and similar applications. Since the detector system of the present invention can provide optimized detection of electromagnetic radiation within a specific wavelength range (including modified wavelengths produced by wavelength modifiers - usually from longer to shorter, but can be from shorter to longer wavelengths), the present invention provides utility in the form of allowing its users to conveniently investigate samples over a large wavelength range without having to reconfigure the system with different electromagnetic radiation sources and electromagnetic radiation detectors. However, other known sources provide wavelengths longer than can currently be produced by supercontinuum lasers (but will certainly be produced by improved supercontinuum lasers in the future), so the present invention also includes its use to enable sample investigation at longer / shorter wavelengths when necessary until improved supercontinuum lasers become available. Note that about five years ago, the wavelength range increased from about 400-2500nm, and currently available supercontinuum lasers provide wavelengths up to at least 4400nm. For example, the IR supercontinuum laser in the NP Photonics SpectraChrome 1000. It is also noted that supercontinuum lasers providing wavelengths up to about 18000nm are available, although at the longest wavelengths, the intensity of the wavelength will decrease. For example, sources from IPG Optoelectronics (CLPF-2500-SC IDFG series) show plots up to 18 microns. However, many such sources extend only up to about 5000 nm. The present invention is considered to encompass the wavelength range of any such possible supercontinuum laser.

[0134] Sample Survey System

[0135] In view of the above, the present invention can first be described as a sample survey system, which is selected from the group consisting of:

[0136] Reflectometer

[0137] Spectrophotometer

[0138] Ellipsometer; and

[0139] Polarimeter;

[0140] The sample survey system comprises:

[0141] a) a spectroscopic beam source of electromagnetic radiation;

[0142] b) a stage for supporting the sample; and

[0143] c) A detector system for monitoring electromagnetic radiation provided from a single sample. Said system is distinguished by:

[0144] The electromagnetic radiation spectroscopic beam source is a supercontinuum laser providing a high intensity, highly directional coherent spectrum of electromagnetic radiation wavelengths in the range of 400 to at least 4400 nm, resulting from the interaction of pulsed laser light and nonlinear processes leading to extensive spectral broadening; and in that the sample interrogation system is characterized by at least one selection from a primary selection group, the primary selection group being:

[0145] First choice group

[0146] In use, said split beam source of electromagnetic radiation directs the beam provided thereby at an angle to a sample placed on said stage for supporting the sample, but does not involve said beam passing sequentially through a combined beam splitter and an objective lens;

[0147] In use, fluorescence arising due to the illumination beam of electromagnetic radiation is not detected by a detector for spatially resolving radiation emitted by the object to be inspected, and neither the illumination beam path between the illumination device and the object to be inspected, nor the detection beam path between the object to be inspected and the detector comprises illumination optics designed to generate a light sheet of illumination radiation extending transversely to the illumination beam path, and wherein the axis of the detection beam path is oriented substantially perpendicular to the light sheet and a cross-sectional plane of the object to be inspected, and neither the illumination beam path between the illumination device and the object to be inspected, nor the detection beam path between the object to be inspected and the detector comprises illumination optics designed to generate a light sheet of illumination radiation extending transversely to the axis of the illumination beam path, and wherein the detection beam path is not oriented at an angle deviating from theta degrees relative to the light sheet and the cross-sectional plane of the object to be inspected; and

[0148] In use, the system does not use a supercontinuum source consisting of a pulsed laser suitable for pumping into a photonic crystal fiber made of chalcogenide glass as a basic element; or from a pumping CO2 laser suitable for emitting into a photonic crystal fiber, the photonic crystal fiber being partially formed by at least one item selected from the group consisting of: AlClxBr(1-x), Nacl and ZnSe; or the system includes a titanium sapphire laser suitable for emitting femtosecond pulses through a nonlinear optical element arranged in an inert gas in a gas-tight chamber, thereby generating second harmonic pulses and generating supercontinuum terahertz wave radiation.

[0149] Note that two or all three selections may be made.

[0150] The sample interrogation system may further comprise a speckle reducer for reducing large fluctuations in electromagnetic radiation intensity as a function of time and position in the beam caused by interference effects between different coherent wavelengths in the widely broadened spectrum.

[0151] The sample investigation system may further include a polarization state generator between the electromagnetic radiation beam source and the sample support stage, and a polarization state analyzer between the sample support stage and the detector, and the system is an ellipsometer or a polarimeter, and optionally further includes a compensator in the polarization state generator and / or the polarization state detector.

[0152] The sample investigation system may include a speckle reducer in the form of a multimode optical fiber.

[0153] The sample interrogation system may include a speckle reducer in the form of a beam diffuser.

[0154] The sample interrogation system may include a speckle reducer in the form of a fly's eye beam homogenizer.

[0155] The sample interrogation system may include a speckle reducer in the form of a rotating beam diffuser.

[0156] The sample interrogation system may include a speckle reducer in the form of a piezoelectric crystal driven beam diffuser.

[0157] The sample interrogation system may include a speckle reducer in the form of an electronic device for shortening the temporal coherence length.

[0158] The sample survey system may further include at least one selected from the group consisting of:

[0159] The system further comprises a Michelson interferometer and in functional combination with the supercontinuum laser source of electromagnetic radiation, the source being a FTIR source;

[0160] The system further includes a wavelength modifier for accepting electromagnetic radiation of relatively long (short) wavelength and providing an output of shorter (longer) wavelength detectable by the detector element(s);

[0161] The detector system comprises a single element;

[0162] The detector system comprises a plurality of detector elements which can detect wavelengths exiting from the wavelength modifier when a relatively longer (shorter) wavelength enters the wavelength modifier, and wherein the detectable wavelengths are directed into the detector elements by selection from at least one of the group consisting of:

[0163] at least one beam splitter;

[0164] at least one combined dichroic mirror and prism; and

[0165] at least one grating; and

[0166] The system also includes a second source that provides a wavelength in a longer or shorter range than provided by the supercontinuum laser.

[0167] The method of investigating a sample of the present invention may include:

[0168] a) providing a sample survey system selected from the group consisting of:

[0169] Reflectometer;

[0170] Spectrophotometer;

[0171] Ellipsometer; and

[0172] Polarimeter;

[0173] include:

[0174] a') a beam source of a split beam of electromagnetic radiation;

[0175] b') a stage for supporting the sample; and

[0176] c') a detector system for monitoring electromagnetic radiation provided from a single sample. The systems are distinguished in that the high intensity, highly directional electromagnetic radiation spectroscopic beam source is a supercontinuum laser that provides a coherent spectrum of electromagnetic radiation wavelengths in a range including 400 to at least 4400 nm, which is caused by the interaction of the pulsed laser and nonlinear processes leading to extensive spectral broadening, the system further includes a second source that provides wavelengths in a longer or shorter range than provided by the supercontinuum laser, and the system is configured so that both sources provide electromagnetic radiation to substantially the same location on the sample as the supercontinuum source.

[0177] The system further comprises a speckle reducer in the form selected from the group consisting of:

[0178] Multimode fiber;

[0179] beam diffuser;

[0180] Fly's Eye Beam Homogenizer;

[0181] Rotating beam diffuser;

[0182] piezoelectric transistor-driven beam diffuser;

[0183] Electronic devices for shortening the temporal coherence length;

[0184] The speckle reducer is used to reduce the strong fluctuations in the intensity of the electromagnetic radiation as a function of position in the light beam, which are caused by interference effects between different coherent wavelengths in the widely broadened spectrum.

[0185] The sample survey system is characterized by at least one selected from the group consisting of:

[0186] First choice group

[0187] The method continues:

[0188] b) causing a speckle-reduced split beam of electromagnetic radiation provided by the supercontinuum laser and speckle reducer to interact with a sample on the stage and then to enter the detector system, and / or causing electromagnetic radiation provided by the second source to interact with a sample on the stage and enter the detector;

[0189] c) analyzing the data provided by the detector to characterize the properties of the sample.

[0190] The detector may comprise a system having at least two detectors and means for allocating a portion of the split beam to each detector based on wavelength.

[0191] Another description of a sample survey system selected from the group consisting of:

[0192] Reflectometer;

[0193] Spectrophotometer;

[0194] Ellipsometer; and

[0195] Polarimeter;

[0196] The sample survey system comprises:

[0197] a) source of electromagnetic radiation beam splitter;

[0198] b) a stage for supporting the sample; and

[0199] c) detector systems for monitoring electromagnetic radiation;

[0200] The systems described differ in that:

[0201] The electromagnetic radiation spectroscopic beam source is a supercontinuum laser that provides a high intensity, highly directional, coherent spectrum of electromagnetic radiation wavelengths in a range including 400 to at least 4400 nm, which is caused by the interaction of the pulsed laser and nonlinear processes resulting in extensive spectral broadening, the system further comprising a second source that provides wavelengths in a range longer or shorter than the wavelengths provided by the supercontinuum laser, the system being configured so that both sources provide electromagnetic radiation to substantially the same location on the sample as the supercontinuum source;

[0202] And the difference is that the sample survey system is characterized by:

[0203] First choice group

[0204] The system further comprises a speckle reducer in the form selected from the group consisting of:

[0205] Multimode fiber;

[0206] beam diffuser;

[0207] Fly's Eye Beam Homogenizer;

[0208] Rotating beam diffuser;

[0209] piezoelectric transistor-driven beam diffuser;

[0210] Electronic devices for shortening the temporal coherence length;

[0211] The speckle reducer is used to reduce the strong fluctuations in the intensity of the electromagnetic radiation as a function of time and position in the beam, which are caused by interference effects between different coherent wavelengths in the widely broadened spectrum.

[0212] The system may further include a polarization state generator between the electromagnetic radiation beam source and the sample support stage, and a polarization state analyzer between the sample support stage and the detector, and the system is an ellipsometer or a polarimeter, and the system may optionally further include a compensator in the polarization state generator and / or the polarization state detector.

[0213] The sample interrogation system may include a speckle reducer in the form of a multimode optical fiber, a beam diffuser, a fly's eye beam homogenizer, a rotating beam diffuser, a piezoelectric crystal driven beam diffuser, or an electronic device for reducing the temporal coherence length.

[0214] Where applicable, the detector system in any embodiment may consist of a selection from the following group:

[0215] Colloid box;

[0216] Bolometer;

[0217] Thermocouple;

[0218] It is composed of photoconductive materials;

[0219] Composed of photovoltaic materials;

[0220] It is composed of deuterated triglycine sulfate (DTGS);

[0221] Composed of HgCdTe(MCT);

[0222] Composed of LiTaO3;

[0223] composed of PbSe;

[0224] consisting of PbS; and

[0225] Composed of InSb;

[0226] The group further comprises:

[0227] The detector system includes a plurality of detector elements that can detect wavelengths directed into its elements by at least one selection from the following group:

[0228] at least one beam splitter;

[0229] at least one combined dichroic mirror and prism; and

[0230] at least one grating;

[0231] Another description of a sample interrogation system for interrogating a sample within a wavelength range between 400 nm and at least 50,000 nm, the sample interrogation system being selected from the group consisting of:

[0232] Reflectometer;

[0233] Spectrophotometer;

[0234] Ellipsometer; and

[0235] Polarimeter;

[0236] And also include:

[0237] a) source of electromagnetic radiation beam splitter;

[0238] b) a stage for supporting the sample; and

[0239] c) At least one detector system for monitoring electromagnetic radiation.

[0240] The source of the electromagnetic radiation split beam is selected from the group consisting of:

[0241] Supercontinuum lasers;

[0242] Nernst luminophore;

[0243] Carbon silicon rod;

[0244] Laser stabilized arc lamp;

[0245] HG arc lamps; and

[0246] Fixed or tunable quantum cascade lasers; and

[0247] They provide wavelengths in the infrared and / or terahertz range.

[0248] The at least one detector system may include detector element(s) that are incapable of detecting long wavelengths of electromagnetic radiation in at least part of the infrared and terahertz range. In this case, the sample investigation system further comprises at least one wavelength modifier that, in use, receives electromagnetic radiation of relatively long (short) wavelengths that are incapable of detection by the element(s) in the at least one detector system and provides as output a shorter (longer) wavelength that the detector element(s) are capable of detecting, and causes the detectable wavelength to enter the at least one detector system comprised of element(s) that are capable of detecting electromagnetic radiation of the shorter (longer) wavelength.

[0249] Another description of the method of investigating a sample includes the following steps:

[0250] a) providing a sample interrogation system for interrogating a sample in a wavelength range comprised between 400 nm and at least 50,000 nm, said sample interrogation system being selected from the group consisting of:

[0251] Reflectometer;

[0252] Spectrophotometer;

[0253] Ellipsometer; and

[0254] Polarimeter;

[0255] And also include:

[0256] a') a source of a split beam of electromagnetic radiation;

[0257] b') a stage for supporting the sample; and

[0258] c') at least one detector system for monitoring electromagnetic radiation;

[0259] wherein the source of the electromagnetic radiation split beam is selected from the group consisting of:

[0260] Supercontinuum lasers;

[0261] Nernst luminophore;

[0262] Carbon silicon rod;

[0263] Laser stabilized arc lamp;

[0264] HG arc lamps; and

[0265] Fixed or tunable quantum cascade lasers;

[0266] They provide wavelengths in the infrared and / or terahertz range.

[0267] The at least one detector system may include detector element(s) that are unable to detect long wavelengths of electromagnetic radiation in at least part of the infrared and terahertz range, and the sample investigation system further includes at least one wavelength modifier, which, in use, receives relatively long (short) wavelength electromagnetic radiation that is unable to be detected by element(s) in the at least one detector system element(s) and provides as output a shorter (longer) wavelength that the detector element(s) are able to detect, and causes the detectable wavelength to enter the at least one detector system composed of detector element(s) that can detect the shorter (longer) wavelength electromagnetic radiation.

[0268] The method continues:

[0269] b) selecting a supercontinuum laser source and further providing a speckle reduction system selected from the group consisting of:

[0270] Multimode fiber;

[0271] beam diffuser;

[0272] Fly's Eye Beam Homogenizer;

[0273] Rotating beam diffuser;

[0274] a piezoelectric transistor-driven beam diffuser; and

[0275] Electronic devices for shortening the temporal coherence length;

[0276] c) placing a sample to be investigated on said stage for supporting the sample;

[0277] d) causing a beam of electromagnetic radiation generated by the supercontinuum laser source to interact with the sample and then enter the at least one detector system for monitoring electromagnetic radiation; causing the beam of electromagnetic radiation to also interact with the speckle reduction system and the wavelength modifier, the wavelength modifier being between the supercontinuum laser source and the at least one detector system, the at least one detector system comprising element(s) that are incapable of detecting long (short) wavelengths of electromagnetic radiation in at least part of the infrared and terahertz range; causing electromagnetic radiation of a wavelength(s) detectable by the element(s) in the at least one detector to enter the at least one detector system; and

[0278] e) analyzing output from the at least one detector to provide insight into characteristics of the sample.

[0279] Another method of investigating a sample includes the following steps:

[0280] a) providing a sample interrogation system for interrogating a sample in a wavelength range comprised between 400 nm and at least 50,000 nm, said sample interrogation system being selected from the group consisting of:

[0281] Reflectometer;

[0282] Spectrophotometer;

[0283] Ellipsometer; and

[0284] Polarimeter;

[0285] And also include:

[0286] a') a source of a split beam of electromagnetic radiation;

[0287] b') a stage for supporting the sample; and

[0288] c') At least one detector system for monitoring electromagnetic radiation.

[0289] The electromagnetic radiation split beam source may be selected from the group consisting of:

[0290] Supercontinuum lasers;

[0291] Nernst luminophore;

[0292] Carbon silicon rod;

[0293] Laser stabilized arc lamp;

[0294] HG arc lamps; and

[0295] Fixed or tunable quantum cascade lasers;

[0296] They provide wavelengths in the infrared and / or terahertz range.

[0297] The at least one detector system may include detector element(s) that are incapable of detecting wavelengths of electromagnetic radiation in at least part of the infrared and terahertz ranges;

[0298] The sample investigation system may further include at least one wavelength modifier, which, in use, receives electromagnetic radiation of a relatively long (short) wavelength that cannot be detected by the detector element (one or more) in the at least one detector system, and provides a shorter (longer) wavelength that can be detected by the detector element (one or more) as output, and allows the detectable wavelength to enter the at least one detector system composed of the element (one or more) that can detect the electromagnetic radiation of the shorter wavelength.

[0299] The method continues:

[0300] b) selecting a source of electromagnetic radiation other than a supercontinuum laser;

[0301] c) placing a sample to be investigated on said stage for supporting the sample;

[0302] d) allowing a beam of electromagnetic radiation to be generated by said source and interact with said sample and then enter said at least one detector system for monitoring electromagnetic radiation;

[0303] causing the beam of electromagnetic radiation to also interact with the wavelength modifier between the source and the at least one detector system comprising detector element(s) incapable of detecting long (short) electromagnetic radiation wavelengths in at least part of the infrared and terahertz range;

[0304] causing electromagnetic radiation of a wavelength(s) detectable by detector element(s) in the at least one detector to enter the at least one detector system; and

[0305] e) analyzing the output from the at least one detector to provide insight into the characteristics of the sample.

[0306] In any of the foregoing examples, where appropriate, the sample interrogation system may provide that a supercontinuum laser source of electromagnetic radiation is functionally combined with a Michelson interferometer; and the detector is selected from the group consisting of:

[0307] Colloid box;

[0308] Bolometer;

[0309] Thermocouple;

[0310] Characterized by a detector comprising a material selected from the group consisting of:

[0311] Deuterated triglycinyl sulfate (DTGS);

[0312] HgCdTe(MCT);

[0313] LiTaO3;

[0314] PbSe;

[0315] PbS;

[0316] InSb; and

[0317] InGaAs.

[0318] Another sample interrogation system according to the invention for interrogating a sample in a wavelength range provides that the sample interrogation system is selected from the group consisting of:

[0319] Reflectometer;

[0320] Spectrophotometer;

[0321] Ellipsometer; and

[0322] Polarimeter;

[0323] The sample survey system comprises:

[0324] a) a beam source of a split beam of electromagnetic radiation selected from the group consisting of:

[0325] Supercontinuum lasers; and

[0326] a source for providing a wavelength longer or shorter than that provided by the supercontinuum laser;

[0327] b) a stage for supporting the sample; and

[0328] c) a detector system for monitoring electromagnetic radiation provided from a single sample. The at least one detector system may include a detector element(s) that is incapable of detecting long (short) wavelengths of electromagnetic radiation within at least a portion of the wavelength range provided by the source. The system may further require the presence of at least one selected from the group consisting of:

[0329] at least one wavelength modifier which, in use, receives electromagnetic radiation of a relatively long (short) wavelength which is not detectable by element(s) in the at least one detector system and provides as an output a shorter (longer) wavelength which is detectable by the detector element(s), the output of the wavelength modifier entering as a detectable wavelength into the detector element(s) of the detector system; and

[0330] a speckle reducer for reducing the strong fluctuations in the intensity of the electromagnetic radiation as a function of time and position in the beam, caused by interference effects between different coherent wavelengths in the widely broadened spectrum;

[0331] The present invention was then discovered in the use of the following combination:

[0332] Application of detector systems;

[0333] Use of supercontinuum lasers;

[0334] Application of speckle reducers;

[0335] The use of additional sources of electromagnetic radiation;

[0336] Application of supercontinuum lasers in Fourier transform infrared sources;

[0337] Application of wavelength modifiers.

[0338] Detector system

[0339] The present invention includes the use of both single element and multi-element detectors. When a beam (whether monochromatic or split) is to be analyzed as a whole, a single element detector may be used, such as:

[0340] Colloid box;

[0341] Bolometer;

[0342] Thermocouple;

[0343] Alternatively, you can use the following detector:

[0344] Photoconductive materials;

[0345] Photovoltaic materials;

[0346] Includes deuterated triglycinyl sulfate (DTGS);

[0347] Including HgCdTe (MCT);

[0348] Including LiTaO3;

[0349] Including PbSe;

[0350] including PbS; or

[0351] Including InSb;

[0352] This is often the case, for example, when a source of electromagnetic radiation is functionally combined with a Michelson interferometer.

[0353] The detector system of the invention may alternatively comprise means (DO) for generating a plurality of independent wavelength ranges from a split beam incident thereon, said system comprising a series of at least two elements, wherein each element is selected from the group consisting of:

[0354] a grating which, when provided with an incident split beam of electromagnetic radiation, produces a spectrum of diffracted dispersed wavelengths and simultaneously produces a reflected beam of electromagnetic radiation having an altered spectral content;

[0355] A combined dichroic beam splitter-prism, when provided with a split beam of electromagnetic radiation, produces a spectrum of dispersed wavelengths which is transmitted through and exits the prism, while producing a reflected beam of electromagnetic radiation having an altered spectral content.

[0356] In use, a spectroscopic beam of electromagnetic radiation from an electromagnetic radiation source is caused to interact with a sample placed on the stage and then impinge on a first selection element, thereby producing a spectrum of dispersed wavelengths and directing it to a first detector, while simultaneously producing a reflected electromagnetic radiation beam with a changed spectral content, which is directed to impinge on a second selection element, which similarly produces a spectrum of dispersed wavelengths that is directed to a second detector.

[0357] A reflected beam of electromagnetic radiation with changed spectral content can be directed to impinge on a beam splitter which directs at least some of the beam to a third selection element which produces a spectrum of dispersed wavelengths that is directed to a third detector, while continuing to direct at least some of the beam with changed spectral content to the second selection element which continues to direct a limited range of spectrum of dispersed wavelengths produced thereby to the second detector.

[0358] The detector system may include functionally enabling at least one option from the group consisting of:

[0359] At least one of the first and second selection elements is designed to optimally structure the wavelength range leaving therefrom;

[0360] At least one of the first and second detectors is designed to optimally detect a wavelength range input thereto by the first and second selection elements, respectively.

[0361] The detector system may further comprise more than two selection elements, and wherein the reflected electromagnetic light beam generated by the second selection element is directed to at least one selection of the group consisting of:

[0362] a dichroic beam splitter, from which it then impinges upon a third selection element;

[0363] Directly impact the third selection element;

[0364] at least one reflector, then a dichroic beam splitter, and then from there impinges on a third selection element; and

[0365] At least one reflector then strikes the third selection element.

[0366] The detector system may provide that the third selection element, upon receiving the reflected beam of electromagnetic radiation, generates a spectrum of dispersed wavelengths which is directed to a third detector.

[0367] The detector system may provide for enabling at least one option from the group consisting of:

[0368] The third selection element is designed to optimally structure the wavelength range departing therefrom;

[0369] The third detector is designed to optimally detect the wavelength ranges input thereto by the first and second selection elements, respectively;

[0370] The detector system may provide for selecting a fourth element and wherein a reflected electromagnetic beam generated by a third selection element or a reflected electromagnetic beam exiting an existing dichroic beam splitter associated with the second selection element is directed to at least one selection from the group consisting of:

[0371] a dichroic beam splitter and from there impinges on a fourth selection element;

[0372] Directly hit the fourth selection element;

[0373] at least one reflector, then a dichroic beam splitter, and from there impinging on a fourth selection element; and

[0374] The at least one reflector then impinges upon the fourth selection element.

[0375] The detector system may provide that the fourth selection element, upon receiving the reflected beam of electromagnetic radiation, generates a spectrum of dispersed wavelengths which is directed to a fourth detector.

[0376] The detector system may provide for enabling at least one option from the group consisting of:

[0377] The fourth selection element is designed to optimally structure the wavelength range departing therefrom;

[0378] The fourth detector is designed to optimally detect the wavelength ranges input thereto by the first and second selection elements, respectively.

[0379] The detector system may specifically involve splitting the beam of electromagnetic radiation from the sample so that it impinges on a grating or combined dichroic beam splitter-prism, which produces a spectrum of the diffraction-dispersed wavelengths, which is directed into the detector; and simultaneously produces a reflected beam of electromagnetic radiation with a changed spectral content, which is directed to interact with a dichroic beam splitter so that the reflected beam of electromagnetic radiation with a changed spectral content is separated into two beams, both of which are directed to independently selected ones of the group consisting of:

[0380] a grating which, when provided with an incident split beam of electromagnetic radiation, produces a spectrum of diffracted dispersed wavelengths and simultaneously produces a reflected beam of electromagnetic radiation having an altered spectral content;

[0381] a combined dichroic beam splitter-prism which, when provided with a split beam of electromagnetic radiation, produces a spectrum of wavelengths which are transmitted through and exit said prism while producing a reflected beam of electromagnetic radiation having an altered spectral content;

[0382] This allows the spectrum of dispersed wavelengths exiting from an existing grating or combined dichroic beam splitter-prism to each enter a separate detector.

[0383] The detector system may be provided such that a spectroscopic beam of electromagnetic radiation from the sample impinges upon a first selection element, thereby producing a spectrum of dispersed wavelengths and directing it to a first detector, while simultaneously producing a reflected beam of electromagnetic radiation with altered spectral content, which is directed to impinge upon a second selection element, which similarly produces a spectrum of dispersed wavelengths directed to a second detector, which is the output beam of an ellipsometer or polarimeter leaving its analyser.

[0384] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements comprising:

[0385] A first grating and a first detector, wherein the reflected beam leaving the first grating is a zero order beam and is directed to a second grating and a second detector.

[0386] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements including:

[0387] A first grating and a first detector, wherein the reflected beam leaving the first grating is a zero-order beam and is directed to a first combined dichroic beam splitter-prism and a second detector.

[0388] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements comprising:

[0389] A dichroic beam splitter that transmits first and second ranges of dispersed wavelengths, respectively, substantially above and below a particular wavelength, each selected from the group consisting of:

[0390] a first grating and a first detector, wherein the reflected beam exiting the first grating is a zero-order beam and is directed to a second grating and a second detector; and

[0391] A first grating and a first detector, wherein the reflected beam exiting the first grating is a zero-order beam and is directed to a first dichroic beam splitter-prism combination and a second detector.

[0392] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements comprising:

[0393] A first combined dichroic beam splitter-prism and a first detector, and wherein a reflected beam reflected from said first combined dichroic beam splitter-prism is directed to a first grating and a second detector.

[0394] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements comprising:

[0395] a first grating and a first detector, wherein the reflected beam generated by the first grating is a zero-order beam and is directed to a second grating and a second detector, and wherein the reflected beam generated by the second grating is a zero-order beam and is directed to a third grating and a third detector.

[0396] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements comprising:

[0397] a first grating and a first detector, wherein the reflected light beam generated by the first grating is a zero-order light beam and is directed to a first combined dichroic beam splitter-prism and a second detector, and wherein the reflected light beam reflected from the first combined dichroic beam splitter-prism is directed to a third grating and a third detector via a dichroic beam splitter.

[0398] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements comprising:

[0399] a first grating and a first detector, wherein the reflected light beam produced by the first grating is a zero-order light beam and is directed to a second grating and a second detector, and wherein the reflected light beam produced by the second grating is a zero-order light beam and is directed to a first dichroic beam splitter-prism combination and a third detector.

[0400] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements comprising:

[0401] a first grating and a first detector, wherein the reflected beam generated by the first grating is a zero-order beam and is directed to a first combined dichroic beam splitter-prism and a second detector, and wherein the reflected beam reflected from the first combined dichroic beam splitter-prism is directed through a beam splitter to a second dichroic beam splitter-prism combination and a third detector.

[0402] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements, the series of elements comprising:

[0403] a first combined dichroic beam splitter-prism and a first detector, wherein a reflected beam reflected by the first combined dichroic beam splitter-prism is directed to a second grating and a second detector, and wherein the reflected beam generated by the second grating is a zero-order beam and is directed to a third grating and a third detector.

[0404] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements comprising:

[0405] a first combination dichroic beam splitter-prism and a first detector, wherein a reflected light beam reflected from the first combination dichroic beam splitter-prism is directed to a second dichroic beam splitter-prism combination and a second detector, and wherein a reflected light beam reflected from the second combination dichroic beam splitter-prism is directed through the dichroic beam splitter to a third grating and a third detector.

[0406] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements comprising:

[0407] a first combined dichroic beam splitter-prism and a first detector, wherein a reflected beam reflected from the first combined dichroic beam splitter-prism is directed to a first grating and a second detector, and wherein the reflected beam generated by the second grating is a zero-order beam and is directed to a second combined dichroic beam splitter-prism and a third detector.

[0408] The detector system may specifically involve a split beam of electromagnetic radiation from the sample interacting with a series of elements comprising:

[0409] a first combined dichroic beam splitter-prism and a first detector, wherein a reflected light beam reflected from the first combined dichroic beam splitter-prism is directed to a second combined dichroic beam splitter-prism and a second detector, and wherein a reflected light beam reflected by the second combined dichroic beam splitter-prism is directed through a beam splitter to a third combined dichroic beam splitter-prism and a third detector.

[0410] The detector system may involve a spectrum of dispersed diffracted wavelengths produced by a grating, which is either a + or - order spectrum.

[0411] It will be appreciated that relatively shorter wavelengths may be modified to longer wavelengths which will be detected by, for example, a Golay cell, a bolometer or a microbolometer, etc. However, since the sources of the present invention provide relatively long wavelengths, the present invention is more likely to include a wavelength modifier for changing relatively longer wavelength electromagnetic radiation to shorter wavelength electromagnetic radiation, in functional combination with, for example, a solid-state detector element which is not capable of monitoring longer wavelengths but can monitor shorter wavelength, higher energy wavelengths.

[0412] A typical configuration in the context of the present invention is that the source provides a wavelength in the infrared and / or terahertz range, and the detector element is solid state, which can only detect higher energy, shorter wavelengths. However, this does not exclude the case where the wavelength modifier inputs a relatively shorter wavelength and outputs a longer wavelength and the detector element is a Golay cell, bolometer or microbolometer, etc. In the case of using a solid state detector element, the present invention provides utility in the form of reduced initial and operating costs, (e.g., cooling when detecting longer wavelengths).

[0413] Where one or more elements are described, the distinction between detector types is indicated. That is, it should be interpreted as applying to the case where the detector comprises a single element and monitors a monochromatic wavelength of a split beam or monitors all wavelengths together, or to the case where the wavelengths are separated and monitored individually.

[0414] The present invention will be better understood by referring to the detailed description of this specification in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0415] Figure 1 Several wavelength ranges are shown in which various multi-channel detectors (DET1)(DET2)(DET3) are designed for optimal processing.

[0416] Figure 2 Some combinations of the present invention of multiple gratings (G) and / or dichroic beam splitter-prism combinations (DBSP) (generally represented as (G / P)) are shown as examples, respectively generating at least one + or - order spectrum of wavelengths and a relatively higher energy reflected light beam (e.g., zero order (ZO) in the case of a grating), an example of an electromagnetic radiation beam directed to a subsequent grating (G).

[0417] Figure 3a A grating (G) is shown which reflects an incident electromagnetic beam (IB) and provides a spectrum of wavelengths (λ) in its order (eg, first + order) together with a zero order (ZO).

[0418] Figure 3a ' shows the case where the reflected (RB) beam is reflected from the dichroic beam splitter-prism (DBS-PR) combination at the surface on which the coating exists to give it dichroic properties. Note that at least the + or - order spectrum of the spectrum leaves the prism (P).

[0419] Figure 4 illustrates an ellipsometer system, in which the present invention finds very relevant application.

[0420] Figure 5 illustrates the use of successive subsequent gratings which successively encounter electromagnetic radiation.

[0421] Figure 6 shows the use of a beam splitter to direct parts of the beam to different detectors which may be optimized to respond to different wavelength ranges.

[0422] Figure 7a and 7b The typical intensity versus position relationship of an electromagnetic radiation beam provided by a supercontinuum laser source in the range of about 400-2500 nm and the effect of a speckle reducer on the Figure 7a The same result is obtained for the curve of

[0423] Figure 8a-8a ”' shows the fly’s eye method for reducing speckle.

[0424] Figure 8b-8f Various speckle reducers are shown.

[0425] Figure 9a and 9b Included to illustrate a basic reflectometer or spectrophotometer system, and a basic ellipsometer or polarimeter system, respectively, including one or more wavelength modifiers (WM).

[0426] Fig.9c A basic FTIR system is shown, including a source of electromagnetic radiation therein.

[0427] Figure 9d and 9e shows a system with dispersive optics and a wavelength modifier (WM) Figure 9a and 9b .

[0428] Figure 9f A basic reflectometer or spectrophotometer system is shown, where two wavelength modifiers (WMs) are present.

[0429] Figure 9g-9i A further example of an ellipsometer system is shown in which a wavelength modifier (WM) is present.

[0430] Fig.10a Included to illustrate a typical inventor-generated intensity versus wavelength resulting from a supercontinuum laser, as compared to the intensity versus wavelength of a typical conventional electromagnetic radiation source.

[0431] Fig.10b Included to show that recent advances have extended the range of supercontinuum lasers to at least 4400 nm, and even up to 18000 nm. DETAILED DESCRIPTION

[0432] First, it should be understood that the invention claimed herein is best shown in Figure 9f-9i In the present invention, it is related to a wavelength modifier (WM) applied in the context of reflectometer, spectrophotometer, ellipsometer and polarimeter sample investigation systems. The wavelength modifier (WM) changes the wavelength of incoming electromagnetic radiation, which can appear before or after the sample (SAM) supporting stage (STG). However, the invention currently claimed also inseparable relates to a source (LS) and a detector (PA) of electromagnetic radiation. The figures herein are adapted from co-pending application 17 / 300,091 (relating to the source (LS) and the detector (DET)) and are discussed in the order presented therein.

[0433] Now go to Figure 1, which shows a number of wavelength ranges that various multichannel detectors (DET1)(DET2)(DET3) are designed to optimally process. Many additional wavelength ranges can also be similarly shown, such as Figure 2 (4) shown.

[0434] Figure 2 Shown is an illustrative use of a source (EM) of an electromagnetic wavelength in the infrared or terahertz range, a typically present aperture and a wavelength modifier (WM) for accepting said infrared or terahertz wavelength and typically providing an output wavelength in a wavelength range detectable by solid-state detector (DET) elements (DE's) (see FIG. 4 ). Figure 2 Also shown are multiple gratings (G) (see Figure 3a ) and / or a dichroic beam splitter-prism combination (DBS-RP) (see Figure 3a ')exist Figure 2 a combination of, each of which generates at least one + or - order spectrum (Δλ) of wavelength, and a reflected beam of electromagnetic radiation (RB / OR) with a changed spectral content, (e.g. a zero order (OR) beam in the case of a grating (G) or a functionally similar reflected beam (RB) in the case of a dichroic beam splitter-prism combination (DBS-PR)) (both possibilities are Figure 2 Indicated by G / P- in the Figure 3a ' about the reflected beam (RB) of the combined dichroic beam splitter-prism (DBS-PR) and Figure 3a (Note that the term zero-order (ZO) is incorrect in the strict sense of applying a dichroic beam splitter-prism combination (DBSP) instead of a grating (G), even though the results provided are functionally similar). Figure 2is an example of the detector system of the present invention, wherein a source (EM) of a beam of electromagnetic radiation (IB) is shown providing electromagnetic radiation through an aperture (AP) and impinging on (G / P1). Leaving (G / P1) is a first range of + or -, typically a primary spectrum of wavelengths (λ), which continues to reflect through a mirror (M) as shown into a detector (DET1). Also shown is a reflected beam (RB) reflected from another mirror (M) and meeting a dichroic beam splitter (DBS), which directs a first amount of the incoming beam to (G / P3), which disperses the beam into a series of wavelengths (), which are directed to a detector (DET3). A second amount of the light beam entering (DBS) exits toward (G / P2) which provides a dispersed series of wavelengths (λ) which are directed to detector (DET2) and also directs the reflected light beam (RB" / OR") to (G / P4) which provides a dispersed series of wavelengths (λ) for detector (DET4). It should be understood that Figure 2 Included to illustrate, the present invention may include a plurality of detectors (DET's), each detector including a plurality of solid-state detector elements (DE's) (see FIG. 4 ) which may detect wavelengths exiting from said wavelength modifier (WM) when relatively longer wavelengths (e.g., in the IR or THz range) enter said wavelength modifier (WM), and wherein said wavelengths from said wavelength modifier (WM) detectable by the solid-state detector elements (DE's) are transmitted through a beam splitter (DBS) and / or a prism / dichroic beam splitter combination (DBS-PR) (see Figure 3a ') and / or grating (G) (see Figure 3a ) are directed to the solid-state detector elements (DE's).

[0435] Figure 3a A grating (G) is shown wherein an input beam (IB) of electromagnetic radiation impinges upon the grating, as a result of which at least one + / - order spectrum of wavelengths is generated together with a zero order (ZO) beam.

[0436] Figure 3a 'Shows a reflected (RB) beam reflected from a dichroic beam splitter-prism (DBS-PR) combination at a surface on which a coating is present to give it dichroic properties. Note that at least the + or - order spectrum of the spectrum leaves the prism (P). A coating (C) is indicated as being present on the surface that the input beam impinges on, and is used to form a dichroic beam splitter (DBS). For insight, dichroism refers to different properties based on wavelength, such as reflection / transmission of electromagnetic radiation.

[0437] It should be understood that Figure 2 The designation (G / P_) will be interpreted as a possible Figure 3a and 3a ' in any system.

[0438] FIG. 4 (which is taken from Liphardt et al. Patent No. 7,345,762) Figure 2 ) is included to illustrate an ellipsometer system in which the present invention finds very relevant application to ellipsometers and polarimeters and similar systems. When so applied, the beam exiting the ellipsometer polarization state analyzer (i.e., (EPCLB) in said FIG. 4 ) is advantageously considered to be attached Figure 2 The beam (IB) shown in . Roughly, Figure 2 The grating (G1) in corresponds to the dispersive element (i.e., grating) in FIG. 4 . Note that FIG. 4 shows an ellipsometer source (LS) which provides an ellipsometer beam (PPCLB) which has been polarized by interaction with the polarizer (P) shown. The beam (PPCLB) is then caused to interact with the sample (MS) shown, indicating that it may be a focused beam at this point. The beam reflected from the sample (MS) may be re-collimated and then passes through the analyzer (A) and emerges as a beam (EPCLB) before being focused (FE) onto a dispersive element (e.g., a grating) which is used to disperse the wavelengths into a multi-element detector (PA). One or two compensators (C) may also be present, as shown in the polarization state generator or analyzer or in systems associated with a polarizer and an analyzer, respectively. Again, for correspondence, the dispersive element is roughly equivalent to Figure 2 Also shown is an indication that the positions of the focusing (SSC) and re-collimating (SSC') lenses can be controlled to optimize the desired effect.

[0439] FIG. 5 (from FIG. 9 in Patent 7,345,762) is included to illustrate the use of consecutive subsequent gratings (eg, G1 and G1') to achieve a desired wavelength in a spectrometer system.

[0440] FIG. 6 (taken from patent 8,169,611 Figure 1 a) is included to illustrate the use of beam splitters (B1 and B2) to direct portions of the beam to different detectors (D1 and D2) that can be optimized to respond to different wavelength ranges. See patents 7,345,762 and 8,169,611 for further description. However, the patents do not suggest that the present invention directs a reflected beam with altered spectral content to a subsequent beam dispersive element. FIG. 6 also illustrates the use of beam splitters to direct portions of the beam to different detectors that can be optimized to respond to different wavelength ranges.

[0441] The + / - orders shown in the figures can generally be described as the wavelength range produced when the grating is provided with an incident split beam of electromagnetic radiation and in response produces a spectrum of diffractive dispersed wavelengths, while producing a reflected beam of electromagnetic radiation with altered spectral content (usually a zero-order beam).

[0442] continue, Figure 7a A typical intensity versus position in the beam cross section of a beam of electromagnetic radiation provided by a supercontinuum laser source in the range of about 400 to at least 4400 nm is shown. It is particularly noted that the effects of interactions between its coherent components can result in very inconsistent intensity curves. Note that speckle can result in instabilities in the wavelength. Supercontinuum lasers can be applied to the presently claimed invention to change the wavelength provided thereby to a wavelength detectable by a solid-state detector (possibly in conjunction with a filter).

[0443] Figure 7b It is shown that the application of a "speckle reducer" to the beam intensity profile in FIG6 allows a much more stable beam intensity versus position relationship in the beam profile to be obtained. This much more stable intensity profile is very suitable for use in metrology systems such as ellipsometers, polarimeters, reflectometers and reflectometers. It is believed that the use of a supercontinuum laser source and a speckle reducer as described in this specification is new and novel, especially in combination with the detector system also described. As described earlier in this specification, coherent sources can lead to interference effects, and the present system includes a speckle reducer, which is selected from the group consisting of:

[0444] Multimode fiber;

[0445] beam diffuser;

[0446] Fly's Eye Beam Homogenizer;

[0447] Rotating beam diffuser;

[0448] piezoelectric transistor-driven beam diffuser;

[0449] Electronic devices for shortening the temporal coherence length;

[0450] This effectively eliminates broad variations in intensity over a range of very small wavelengths (i.e., speckle).

[0451] Figure 8a-8a ”' shows a beam homogenization method for reducing speckle. Note that, Figure 8aIt is shown that input electromagnetic radiation is shown as (EMI), which has a very uneven intensity, but can be converted into output electromagnetic radiation shown as (EMO), which has a very flat intensity. The system consists of a beam expander (BE), a beam collimator (BC1), two fly-eye lenses (MF1) (MF2), a second beam collimator (BC2) applied to focus the collimated beam leaving (MF2), and a second beam collimator (BC2) to re-collimate the beam provided to it. The energy content of (EM1) has been evenly distributed by the action of the fly-eye lenses (MF1) and (MF2), as indicated by (EMO). Figure 8a ' and 8a" show a typical fly's eye lens structure. Figure 8a ” is included to indicate Figure 8a How the system (BH) can be applied to an ellipsometer system. An incoming beam from a source (LS) at "A" is shown as (EMI), and the distribution of the beam energy at "B" is shown as (EMO), and a polarizing element (DE) can be applied before the beam interacts with the sample, and a position (D) where a detector is positioned to monitor the reflected beam from position (D) on the sample.

[0452] Figure 8b-8f Various other speckle reducers are shown. Figure 8b A beam diffuser plate is shown into which an input beam (BI) enters and exits as a diffuse beam (DBO) component. Figure 8c is a simple fly's eye lens (FE), when the light beam passes through it, it causes Figure 8b A similar effect to the beam diffuser in FIG. Figure 8d Shows Figure 8b The beam diffuser (BD) is attached to a motor (M) which causes it to rotate in use. The input beam (B) passes through this again as shown and emerges as a diffused beam (DBO). Figure 8e As shown Figure 8b The beam diffuser (BD) plate in the embodiment is attached to a piezoelectric actuator (PZ) used to vibrate the beam diffuser (BD) vertically and / or horizontally in use. The fly eye (FE) lens can also be used to Figure 8d and Figure 8e Configuration. Figure 8f An end view of a multimode fiber is shown. Note the core region 1 and the outer region 2. In a multimode fiber, region 1 is a significant portion of region 2. The region 1 core is not as prominent in a single mode fiber.

[0453] Figure 9a Included to illustrate a basic reflectometer or spectrophotometer system, comprising:

[0454] a) electromagnetic radiation beam source (S);

[0455] b) a stage (STG) for supporting a sample (SAM);

[0456] c) Electromagnetic detector system (DET);

[0457] In the present invention, the system is distinguished in that the electromagnetic radiation spectroscopic beam source (S) is provided as follows Figure 7a And preferably a supercontinuum laser with an output spectrum as shown in 7b. That is, the main distinguishing aspect of the present invention is the use of a high-intensity, highly directional supercontinuum laser to provide electromagnetic radiation. Figure 2 As described, another aspect of the invention involves the use of a detector system that provides various ranges of wavelengths to a detector that is well suited to detect said wavelengths.

[0458] Figure 9b Shows Figure 9a Components of the invention, with the addition of a polarization state generator (PSG) and a polarization state analyzer (PSA) to realize an ellipsometer or polarimeter system. (Note that if more than one source (S) is mentioned in this specification, the designation of (S) in any related figure should be interpreted as representing the source being used.)

[0459] It should be understood that the aforementioned detector system may provide that there is a Figure 2 There may be multiple multi-element arrays as shown in FIG. 4 or a single array as shown in FIG. Figure 9a and 9b Indicates a single detector. Figure 9d and 9e is shown modified to include detector (DET) array elements (DE's) Figure 9a and 9b The detector side of the system is shown. Note that Fig.9e The wavelength modifier (WM) in the detector is moved from before the dispersive optical device to after it. In any configuration, the functional element (one or more) that provides the measurable electrical signal can be solid-state (e.g., a CCD array) or a signal element, such as a Golays cell or a bolometer. The latter detector can be applied to monitor electromagnetic radiation at infrared and terahertz frequencies. The Golays cell converts temperature changes caused by electromagnetic radiation into a signal that can be electrically monitored. For example, there may be a deformable diaphragm / film that reflects electromagnetic radiation into one or another photocell. Deformation of the shape of the diaphragm / film in the Golays cell chamber causes electromagnetic radiation to be guided into the monitoring photocell. The bolometer operates by converting the resistance change caused by the electromagnetic radiation hitting the blackened material. Further, the detector may include a wavelength modifier, where applicable, for changing the far infrared frequency / wavelength to the near infrared frequency / wavelength, thereby allowing the use of cheaper and easier to use silicon-based components. Figure 9a ,9b , 9d and 9e identify a wavelength modifier (WM). An example of a wavelength modifier that converts a longer wavelength to a shorter wavelength is a NLIR non-linear infrared sensor, which changes mid-infrared wavelengths to near visible wavelengths. Fig.9c Included to indicate that the electromagnetic radiation source (S) can be part of a Fourier transform interferometer (FTIR) system. Shown are the source (S), the beam splitter (BS) and two mirrors (M1) and (M2). In use, the mirror M1 is moved up and down as shown. This increases and decreases the path length of the beam from the beam splitter (BS) to there. Due to interference at the beam splitter, interference between the beam between the beam splitter (BS) and the mirror (M1), and interference between the beam between the beam splitter (BS) and the mirror (M2), various wavelengths are transmitted and blocked at different positions of the mirror (M1).

[0460] Figure 9f A basic reflectometer or spectrophotometer system is shown with two wavelength modifiers (WM). Typically only one of these is present, so the two shown should not be construed as limiting, but note that when only one is present it can be located on either side of the stage (STG). When the wavelength modifier is present in front of the stage (STG), the sample interrogation system is converted into a system that interrogates the sample (MS) in a different wavelength range than that provided by the electromagnetic radiation source (LS). This can be useful if it is desired to interrogate the sample using a very wide wavelength range using the same sample interrogation system without having to change the electromagnetic radiation source (LS).

[0461] Figure 9g-9i A further example of an ellipsometer system is shown with a wavelength modifier (WM) in various positions after the stage (STG). The system shown includes a spectroscopic electromagnetic radiation source (LS), a polarizer (P), a compensator (C) (note that (P) and (C) combined form (PSG)), a sample (MS) on the stage (STG), a second compensator (C') and an analyzer (A') (note that (C') and (A) form (PSA)), a focusing element (FE), a dispersive optic, and a detector (PA) including a plurality of detector elements (DE's). Figure 9g In the embodiment, a wavelength modifier (WM) is present between the stage (STG) and the dispersive optical device. Figure 9h A beam splitter (BS) and a mirror (M) are further included to provide two detector arrangements, both having a wavelength modifier (WM) present between the stage (STG) and the dispersive optics. Figure 9i and Figure 9gThe difference is that the wavelength modifier (WM) is present between the dispersive optics and the detector (PA). Any such arrangement is considered to be within the scope of the present invention. Figure 9g-9i The location of the wavelength modifier (WM) in an illustrative inventive system is shown. Also note that, Figure 9g The configuration can exist in Figure 9h-9i That is, whether the system is a reflectometer, spectrophotometer, ellipsometer or polarimeter, a wavelength modifier (WM) can be present between the source (LS) and the stage (STG).

[0462] Note that the polarizer (P), analyzer (A) or compensator (one or more) (C), (as shown in FIG. 6 or as Figure 9b The polarization state generator (PSG) or polarization state analyzer (PSA) shown incorporated may be stationary in use, or some or all may be rotated.

[0463] Fig.10a Included to show a typical intensity versus wavelength relationship resulting from a supercontinuum laser generated by the inventors of the present invention when a 0.0325% neutral density filter is present in the path of the supercontinuum laser beam, as compared to the intensity versus wavelength relationship of a conventional electromagnetic radiation source. Note that the supercontinuum laser intensity is much greater than the intensity of the conventional source spectrum (approximately 30 times greater as shown), and in order to compare their wavelength spectral characteristics, it is necessary to attenuate it significantly by the 0.0325 neutral density filter.

[0464] Fig.10b is included to show how far supercontinuum laser sources have come since the patent application was filed. Note that Fig.10a compared to, Fig.10b The wavelength range is greatly expanded in the . It is expected that further expansion of the wavelength range will continue, and the present invention should be considered from this perspective. That is, Fig.10a and 10b The supercontinuum laser source wavelength ranges shown in are exemplary and not limiting. For example, supercontinuum laser sources providing wavelengths up to 18000 nm are available, although the intensity decreases at longer wavelengths.

[0465] Having disclosed the subject matter of the present invention herein, it should be apparent that many modifications, substitutions and variations of the present invention are possible in view of the teachings of the present invention. Therefore, it should be understood that the present invention may be implemented in ways other than those specifically described, and should be limited only by the claims in its breadth and scope.

Claims

1. A sample survey system selected from the group consisting of: Ellipsometer; Polarimeter; Reflectometer; as well as Spectrophotometer; For use in investigating samples using electromagnetic radiation; The system comprises: Electromagnetic radiation source (LS); a stage (STG) for supporting a sample; and a detector (PA) comprising detector elements (DE's); The electromagnetic radiation source (LS) provides electromagnetic radiation of long wavelength in the IR and THz range, and the detector is incapable of detecting the IR and THz wavelengths; The system is characterized in that, before the detector (PA), there is at least one wavelength modifier (WM), which is used to accept electromagnetic radiation of a wavelength outside the range that the detector (PA) can detect and, based thereon, to provide output electromagnetic radiation of a wavelength that the detector can detect; The sample interrogation system further comprises a polarization state generator (PSG) and a polarization state analyzer (PSA) assembly respectively before and after the stage (STG).

2. A sample investigation system according to claim 1, wherein the at least one wavelength modifier (WM) accepts electromagnetic radiation including wavelengths in the IR and THz ranges and outputs electromagnetic radiation having a wavelength in the visible wavelength range.

3. A sample interrogation system as claimed in claim 1, wherein the at least one wavelength modifier (WM) receives electromagnetic radiation including wavelengths in the far IR range and outputs electromagnetic radiation having wavelengths in the visible wavelength range.

4. A sample interrogation system as claimed in claim 1, wherein the at least one wavelength modifier (WM) accepts electromagnetic radiation comprising wavelengths in the mid-IR range and outputs electromagnetic radiation having wavelengths in the visible wavelength range.

5. A sample interrogation system as claimed in claim 1, wherein the at least one wavelength modifier (WM) receives electromagnetic radiation including wavelengths in the near IR range and outputs electromagnetic radiation having wavelengths in the visible light wavelength range.

6. The sample investigation system according to claim 1, further comprising a dispersion device (DO) for spatially separating different wavelengths present after the stage (STG), and wherein the wavelength modifier is placed in one of the following options: between the electromagnetic radiation source (LS) and the stage (STG); between the stage (STG) and the dispersion device (DO); between the dispersion device (DO) and the detector (PA).

7. A sample investigation system according to claim 1, comprising at least two wavelength modifiers between the electromagnetic radiation source (LS) and the detector (PA).

8. A sample survey system selected from the group consisting of: Ellipsometer; Polarimeter; Reflectometer; as well as Spectrophotometer; For use in investigating samples using electromagnetic radiation; The system comprises: Electromagnetic radiation source (LS); a stage (STG) for supporting a sample; and a detector (PA), including detector elements (DE's); The electromagnetic radiation source (LS) provides electromagnetic radiation in a wavelength range that is longer or shorter than that detectable by the detector (PA); The system is characterized in that, before the detector (PA), there is at least one wavelength modifier (WM), which is used to accept electromagnetic radiation of a wavelength outside the range that the detector elements (DE's) of the detector (PA) are capable of detecting, and based thereon to provide output electromagnetic radiation of a wavelength that the detector (PA) is capable of detecting; The electromagnetic radiation source is selected from the group consisting of: Ar, Xe and He discharge lamps in the UV region; Tungsten lamps in the visible light region; Blackbody radiators, Nernst luminophores and carbon silicon rods in the infrared range; Hg and Na linear production lamps in the UV and visible range; Lasers in the visible and IR range; and A supercontinuum laser having a wavelength in the range of 400 nm to 18000 nm; and the detector is characterized by being selected from the group consisting of: Colloid box; Bolometer; Microbolometer; Thermocouple; Photoconductive materials; Deuterated triglycinyl sulfate (DTGS); HgCdTe(MCT); LiTaO3; PbSe; PbS; InSb; and Silicon, Germanium, and Gallium Arsenide solid-state devices.

9. A sample investigation system as claimed in claim 8, wherein the electromagnetic radiation source (LS) provides electromagnetic radiation having a wavelength in a range selected from: Ultraviolet light; Visible light; Far infrared; Mid-infrared; Terahertz waves.

10. The sample investigation system of claim 9, wherein the detector detects wavelengths within a range selected from: Ultraviolet light; Visible light; Far infrared; Mid-infrared; Terahertz waves; The selected range is different from the range provided by said electromagnetic radiation source (LS).

11. A sample investigation system as claimed in claim 10, wherein the electromagnetic radiation source provides a wavelength within a range selected from: Far infrared; Mid-infrared; Near infrared; and Terahertz waves; And the wavelength modifier provides a wavelength within a range selected from the group consisting of: Ultraviolet light; and Visible light.

12. A sample investigation system according to claim 8, comprising at least two wavelength modifiers between the electromagnetic radiation source (LS) and the detector (PA).

13. A method for investigating a sample, comprising the steps of: a) providing a system, said system being selected from the group consisting of: Ellipsometer; Polarimeter; Reflectometer; as well as Spectrophotometer; For use in investigating samples using electromagnetic radiation; The system comprises: Electromagnetic radiation source (LS); a stage (STG) for supporting a sample; and a detector (PA) comprising detector elements (DE's); The electromagnetic radiation source (LS) provides electromagnetic radiation in a wavelength range that is longer or shorter than what the detector elements (DE's) are capable of detecting; The system is characterized in that, before the detector (PA), there is at least one wavelength modifier (WM), which is used to accept electromagnetic radiation of a wavelength outside the range that the detector (PA) can detect and, based on this, provide output electromagnetic radiation of a wavelength that the detector (PA) can detect; The electromagnetic radiation source is selected from the group consisting of: Ar, Xe and He discharge lamps in the UV region; Tungsten lamps in the visible light region; Blackbody radiators, Nernst luminophores and carbon silicon rods in the infrared range; Hg and Na linear production lamps in the UV and visible range; Lasers in the visible and IR range; and A supercontinuum laser having a wavelength in the range of 400 nm to 18000 nm; and the detector is characterized by being selected from the group consisting of: Colloid box; Bolometer; Microbolometer; Thermocouple; Photoconductive materials; Deuterated triglycinyl sulfate (DTGS); HgCdTe(MCT); LiTaO3; PbSe; PbS; InSb; and Silicon, germanium, and gallium arsenide solid-state devices; b) placing the sample to be investigated on the stage (STG); c) causing the electromagnetic radiation source (LS) to provide electromagnetic radiation including a wavelength that cannot be detected by the detector (PA) and directing its beam to the sample; d) causing the wavelength modifier to receive wavelengths of electromagnetic radiation different from those provided by the electromagnetic radiation source (LS) and to modify them to wavelengths detectable by the detector (PA); e) causing the detector (PA) to detect the modified electromagnetic radiation and provide output data; f) analyzing the output data to determine sample characteristics.

14. The method of claim 13, wherein the system further comprises a dispersive device (DO) for spatially separating different electromagnetic wavelengths, the wavelength modifier (WM) being positioned between the electromagnetic radiation source (LS) and the detector (PA).

15. The method as claimed in claim 14, wherein the at least one wavelength modifier is placed between the electromagnetic radiation source (LS) and the stage (STG).

16. The method as claimed in claim 14, wherein said at least one wavelength modifier is placed between said stage (STG) and said dispersive device (DO).

17. The method as claimed in claim 14, wherein said at least one wavelength modifier (WM) is positioned between said dispersive device (DO) and said detector (PA).

18. The method of claim 13, wherein the system comprises at least two wavelength modifiers between the electromagnetic radiation source (LS) and the detector (PA).

19. A method for investigating a sample using electromagnetic radiation of different wavelengths provided by an electromagnetic radiation source, comprising the steps of: (a) providing a system, the system being selected from the group consisting of: Ellipsometer; Polarimeter; Reflectometer; as well as Spectrophotometer; For use in investigating samples using electromagnetic radiation; The system comprises: Electromagnetic radiation source (LS); a stage (STG) for supporting a sample; and a detector (PA) comprising detector elements (DE's); The system further comprises a polarization state generator (PSG) and a polarization state analyzer (PSA) component respectively before and after the stage (STG); The electromagnetic radiation source (LS) provides electromagnetic radiation in a wavelength range that is longer or shorter than that detectable by the detector (PA); The system is characterized in that, before the stage (STG), there is a wavelength modifier (WM); (b) placing a sample to be investigated on the stage (STG); (c) causing the electromagnetic radiation source (LS) to provide electromagnetic radiation and direct its beam to the sample; (d) causing the wavelength modifier (WM) to receive wavelengths of electromagnetic radiation within a first range provided by the electromagnetic radiation source (LS) and to emit wavelengths within a modified range; (e) causing the detector (PA) to detect the modified wavelength of electromagnetic radiation after interaction with the sample (MS) and provide output data; and (f) analyzing the output data to determine sample characteristics.

20. The method of claim 19, further comprising a step (d') between steps (d) and (e): placing a second wavelength modifier (WM) between the stage (STG) and the detector (PA) to place the wavelength from the sample (MS) within the range detectable by the detector (PA).

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