JPWO2020013517A5 - - Google Patents

Description

The present invention relates to a vertical incidence ellipsometer and a method for measuring optical properties of a test piece using the same. More specifically, the present invention relates to a normal incidence ellipsometer used to measure and analyze changes in the polarization state of light reflected by a test piece to measure optical properties of the test piece, and a test piece using the same. relates to a method for measuring optical physical properties.

With the rapid development of various industrial fields such as semiconductor devices, flat panel displays, thin-film solar cells, nano-imprint, nano-bio, and thin-film optics, the thickness of thin films is getting smaller and smaller, down to the level of several atomic layers. However, the shape of nanopatterns tends to be complicated from the existing two-dimensional structure to the three-dimensional structure. Along with this, the manufacturing process steps of such products are non-contact so as not to damage the nanospecimens, and the shape and physical properties of the nanoscale specimens, such as thin film thickness, nanopattern shape, etc., can be more accurately determined. There is a growing need for process metrology for analysis. Among such non-contact nanoscale measurement techniques, ellipsometers and methods using them are widely used with the development of light sources, photodetectors, computers, and the like.

Based on the angle of incidence, ellipsometers are classified into vertical incidence type and oblique incidence type. The vertical incidence method is a method of measuring the change in the polarization state of the light reflected vertically by the test piece when the measurement beam is incident on the surface of the test piece perpendicularly (that is, the incident angle is 0 degrees). The incident method is a method in which the incident angle of the measurement beam is arbitrarily selected within the range of 0 to 90 degrees for measurement. Among them, the vertical incidence method has the advantage that the size of the measuring apparatus can be made smaller and the measuring beam can be made small so that a smaller area of the internal region of the test piece can be measured. Various patent documents such as US Pat. No. 7,355,708 and US Pat. No. 7,889,340 and various other papers disclose in detail the basic configuration and principle of the normal incidence type ellipsometer.

[Basic Configuration of Vertical Incidence Ellipsometer]
An optical element-rotating ellipsometer basically consists of a light source (Light Source; LS), a polarization state generator (PSG), a specimen (Sample; SP), a polarization state analyzer (Polarization State Analyzer), A detection optical system (DOS) and a photodetector element (PDE) can be included, and a brief description of each part is as follows. The light source serves to collimate light emitted from a lamp or the like using an optical system. A polarization state generator is a polarizing optical system that serves to bring a collimated beam emitted from a light source into a particular polarization state. The specimen is placed on the path of travel of the modulated incident parallel beam. A polarization state analyzer is a polarization optical system that serves to analyze the polarization state of the reflected parallel beam on the traveling path of the reflected parallel beam reflected from the test piece. The photodetector functions to measure the amount of light of the reflected parallel beam of the designated wavelength band that has passed through the polarization state analyzer as a value such as voltage or current. Optical property values of the test piece can be calculated from the measured voltage or current values and stored or displayed on the screen. The detection optics are placed on the reflected parallel beam axis between the polarization state analyzer (PSA) and the photodetector element (PDE), but with an optical element capable of imparting a change in the polarization state of the reflected parallel beam. A virtual polarizing optical system having the same effect may include a beam splitter and a reflecting mirror and a grating mounted inside a spectrometer.

As mentioned above, the polarization state generator or polarization state analyzer consists of a form of polarization optics in which a plurality of rotatable polarization optical elements are appropriately arranged to perform their respective roles. At this time, at least one selected rotatable polarized light element among the rotatable polarized light elements rotates at a constant velocity, and the remaining rotatable polarized light elements other than the constant velocity rotated polarized light elements are: As a fixed polarizing optical element, it may move to a pre-specified azimuth angle for measurement and be stopped at the time of measurement.

The type and arrangement of the rotatable polarizing optical element may vary depending on the type of ellipsometer. Specifically, the rotatable polarizing optical element is composed of a linear polarizer and a compensator. can be Also, when the linear polarizer is arranged in the polarization state generator, it is called a polarizer, and when it is arranged in the polarization state analyzer, it is separately called an analyzer. The compensator is separately referred to as an incident axis compensator when placed in the polarization state generator, and as a reflection axis compensator when placed in the polarization state analyzer.

Conventional optical device-rotational ellipsometers are classified into an oblique incidence type and a vertical incidence type based on the angle of incidence. The incident angle is defined as the plane of incidence (incident plane), which includes the paths of the incident parallel beam and the reflected parallel beam among various planes perpendicular to the plane of the specimen, and the incident plane is perpendicular to the plane of the specimen. When the axis is defined as a reference axis, the internal angle between the incident parallel beam or the reflected parallel beam and the reference axis is defined as the incident angle and denoted by φ. The normal incidence method employs an optical structure with an incident angle of 0 degrees, and the oblique incidence method employs an optical structure with an incident angle other than 0 degrees. The advantages of the vertical incidence method compared to the oblique incidence method are that the size of the measuring device can be reduced, the area of the beam incident on the test piece can be reduced, and the inside of a minute area can be reduced. can be measured.

A brief description of the principle of oblique or normal incidence optical element-rotational ellipsometer is as follows. Oblique or Normal Incidence Optical Elements—In a rotating ellipsometer, an incident parallel beam emitted from a light source is incident on a polarization state generator, which changes the incident parallel beam to a specific polarization state that can be steered by the polarization state generator, The incident parallel beam modulated to the polarization state is irradiated to the test piece, the polarization state is changed by the test piece, and becomes the reflected parallel beam having the optical property information of the test piece, and the reflected parallel beam is incident on the polarization state analyzer. and changed again to a specific controllable polarization state, and the reflected collimated beam undergoing such a series of changes was measured as an electrical signal such as voltage or current using a photodetector and measured by a computer instrument. A series of processes are performed to finally obtain the optical physical property information of the test piece from the electrical signal.

A single-compensator-rotation type vertical incidence that is configured by arranging only one linear polarizer and one constant velocity rotation compensator in implementing a polarization state generator and a polarization state analyzer in a conventional normal incidence ellipsometer A double compensator-rotational normal incidence ellipsometer is disclosed, which consists of an ellipsometer, a linear polarizer, and two constant velocity rotation compensators.

[Configuration of Conventional Vertical Incidence Ellipsometer]
Referring to FIG. 1, one embodiment of a conventional normal incidence ellipsometer, a single compensator-rotational normal incidence ellipsometer 10, includes a light source 11, a beam splitter 12, a linear polarizer 13, It includes a constant velocity rotation compensator 14, a spectrometer 15 (Spectrometer), and a computing device 16 (Processor).

A description of the single compensator-rotational normal incidence ellipsometer 10 of FIG. 1 in terms of the basic structure of the measurement principle follows. An incident parallel beam L10a emitted from the light source 11 travels perpendicularly to the surface of the test piece 1000 by the light splitter 12 and is incident on the fixed polarizer (implemented by the linear polarizer 13). The incident parallel beam L10a incident on the fixed polarizer passes through the fixed polarizer and a uniform rotation incident axis compensator (embodied in the uniform rotation compensator 14) in order, and the polarization state of the incident parallel beam L10 is modulated. , L10b incident on the test piece 1000; The reflected parallel beam L10c reflected by the test piece 1000 is incident on a constant velocity rotation reflection axis compensator (also embodied in the constant velocity rotation compensator 14), and the reflected parallel beam L10c incident on the constant velocity rotation reflection axis compensator is , a constant velocity rotary reflection axis compensator and a fixed analyzer (also embodied in a linear polarizer 13) in sequence, and the polarization state is also modulated, and is incident on the spectrometer 15 by the light splitter 12. L10d. The reflected parallel beam L10d incident on the spectroscope 15 is split into individual wavelengths, converted into electrical digital signal values by the photodetectors in the spectroscope 15, and the measured digital signal values are sent to the computer 16. is used to analyze the optical physical properties of the test piece 1000 by.

In the embodiment of FIG. 1, the detection optics include a light splitter 12, a reflector resident in the spectroscope 15, gratings, and the like. Also, in the embodiment of FIG. 1, the linear polarizer 13 serves not only as a fixed polarizer but also as a fixed analyzer, and the uniform rotation compensator 14 serves not only as a uniform rotation incident axis compensator, but also as Simultaneously play the role of a fast-rotating reflection axis compensator. Therefore, there is an advantage that the size of the measuring apparatus can be reduced compared to the oblique incidence method.

A linear polarizer is mainly manufactured by processing and assembling a crystal having a birefringence characteristic such as MgF2, CaCO3 and SiO2 into a prism shape. Of the electric field components of the light incident on the linear polarizer, the component in the direction of the transmission axis of the linear polarizer can be transmitted, and the component perpendicular to the transmission axis cannot be transmitted. become. In the case of a prism-type linear polarizer without optical activity, the linear polarization state of transmitted light is not affected by the type of wavelength, and the Rochon type linear polarized light made of MgF2 is used. In the case of light, it can be used for the optical band wavelength region from 150 to 6,500 nm.

On the other hand, when light with arbitrary polarization characteristics passes through the compensator, among the electric field components of the light incident on the compensator, the component passing in the fast axis direction and the slow axis perpendicular to it It is most ideal that the phase retardation difference between the components passing in the slow axis direction is 90 degrees, that is, it is made to play the role of a λ/4 wave plate. However, when using a large number of wavelengths, there is a problem that it is practically difficult to fabricate such a compensator. Specifically, in order to create a spectroscopic ellipsometer that includes a compensator capable of real-time measurement of multiple wavelengths, it is necessary to create a compensator suitable for the measurement wavelength range, which is difficult to manufacture. There is In addition, since the phase delay value of the compensator is different for each wavelength, the phase delay value must be found through a calibration process before being used for measurement, but the calibration method is very complicated. Therefore, there is also the problem that errors can occur during the course of the calibration procedure.

Referring to FIG. 2, another embodiment of a conventional normal incidence ellipsometer, a dual compensator-rotational normal incidence ellipsometer 20, includes a light source 21, a light splitter 22, a linear polarizer 23, and a first etc. A fast rotation compensator 24a, a first wave plate 24aw (Waveplate), a first constant-velocity rotary hollow shaft motor 24am, a second constant-velocity rotation compensator 24b, a second wave plate 24bw, and a second constant-velocity rotation. A hollow shaft motor 24bm, a spectrometer 25, a computing device 26, a shielding booth 27, and a gas supply device 28 are included. Unlike the single compensator-rotational normal incidence ellipsometer 10, the double compensator-rotational normal incidence ellipsometer 20 has a second constant velocity rotation compensator 24b, a first It further includes a wave plate 24aw, a second wave plate 24bw, and the like. Light having a wavelength smaller than the wavelength region of deep UV is easily absorbed by oxygen and moisture in the path of the measurement beam. The system is shielded and further provided with a Purging System that fills the measurement beam path with a gas such as high purity nitrogen or high purity argon using a gas supply 28 .

The dual compensator-rotational normal incidence ellipsometer 20 of FIG. 2 is described in terms of the basic structure of the measurement principle as follows. An incident parallel beam L20a emitted from a light source 21 is incident on a fixed polarizer (implemented by a linear polarizer 23) by a light splitter 22 in a direction perpendicular to the plane of the test piece 1000. FIG. The incident parallel beam L20a incident on the fixed polarizer is passed through the fixed polarizer of the incident optical axis phase, the first constant rotation incident axis compensator (embodied in the first constant rotation compensator 24a), and the second constant rotation incident axis compensator (second constant velocity rotation compensator 24a). The polarization state of the incident parallel beam is modulated by sequentially passing through the second uniform rotation incident axis compensator (embodied in the rotation compensator 24b), and L20b is incident on the test piece 1000. FIG. The reflected parallel beam L20c reflected by the test piece 1000 is reflected by the first constant rotation reflection axis compensator (also embodied in the second constant rotation compensator 24b) on the reflected optical axis, 24a) and through a fixed analyzer (also embodied by linear polarizer 23), the polarization state of the reflected parallel beam is modulated, and passed through the optical splitter. 22 makes L20d incident on the spectroscope 25 . The reflected parallel beam L20d incident on the spectroscope 25 is split into respective wavelengths, and the reflected parallel beam L20d is converted into an electrical digital signal value by a photodetector in the spectroscope 25, and the measured digital signal The values are used by computing equipment 26 to analyze the photophysical properties of specimen 1000 .

In the embodiment of FIG. 2, the linear polarizer 23 acts not only as a fixed polarizer, but also as a fixed analyzer. In addition, in the embodiment of FIG. 2, the first uniform rotation compensator 24a and the first wave plate 24aw serve not only as the first uniform rotation incident axis compensator but also as the second uniform rotation reflection axis compensator. As a result, the second constant velocity rotation compensator 24b and the second wave plate 24bw of FIG. 2 serve as not only the second constant velocity rotation incident axis compensator but also the first constant velocity rotation reflection axis compensator. With such a configuration, there is an advantage that the size of the measuring apparatus can be made smaller than that of the oblique incidence method.

However, the dual compensator-rotational normal incidence ellipsometer 20, like the single compensator-rotational normal incidence ellipsometer 10, also suffers from manufacturing and calibration complications arising from the wavelength dependence of the compensator and waveplate. still contains the problem.

In summary, an ellipsometer basically comprises a Polarization State Generator (PSG) and a Polarization State Analyzer (PSA). In the case of a conventional normal incidence ellipsometer, a fixed linear polarizer and one or two constant velocity rotation compensators are used as a configuration that specifically implements the polarization state generator and the polarization state analyzer. However, such a compensator is wavelength-dependent, with the relative phase delay having different values depending on the wavelength. can occur. In addition, when trying to expand the measurement wavelength range to improve the reliability of the measurement, there is also the problem that a new compensator suitable for that needs to be developed.

U.S. Patent No. 7355708 (“Normal incidence rotating compensator ellipsometer”, 2008.04.08.) US Patent No. 7889340 (“Normal-incidence ellipsometer with complementary waveplate rotating compensators “, 2011.02.15.)

1. R.M.A. Azzam, "PIE: Perpendicular-Incidence Ellipsometry - Application to the Determination of the Optical Properties of Uniaxial and Biaxial Absorbing Crystals," Opt. Commun. 19, 122 (1976). 2. R.M.A. Azzam, "NIRSE: Normal-Incidence Rotating-Sample Ellipsometer," Opt. Commun. 20, 405 (1977). 3. Y. J. Cho, et. al., "Universal Evaluations and Expressions of Measuring Uncertainty for Rotating-Element Spectroscopic Ellipsometers," Opt. Express 23, 15481 (2015).

Therefore, the present invention has been devised to solve the problems of the prior art as described above, and the present invention employs a linear polarizer having no wavelength dependence instead of a compensator having wavelength dependence. To provide a vertical incidence ellipsometer and a method for measuring optical physical properties of a test piece using the same, which simplifies equipment calibration procedures and facilitates extension of the measurement wavelength range. With the goal.

The normal incidence ellipsometer of the present invention for achieving the objects as set forth above includes a collimating optical system, a light source emitting an incident collimated beam toward a test piece, and a light source positioned between the light source and the test piece. a light splitter for directing a portion of the incident parallel beam in a direction perpendicular to the plane of the test piece; and a preset orientation disposed between the light splitter and the test piece. a fixed polarizer fixed at an angle and allowing the incident parallel beam to pass only a linearly polarized component in a preset direction; A constant velocity rotation polarizer that regularly modulates the polarization state of the parallel beam according to the constant rotation frequency, and light that receives the reflected parallel beam reflected from the test piece and measures the exposure amount of the spectral radiant flux . a constant-velocity rotation detector disposed between the test piece and the photodetector, rotating at a constant velocity to regularly modulate the polarization state of the reflected parallel beam in accordance with the constant-velocity rotation frequency; A fixed detector disposed between photons, the constant velocity rotating analyzer, and the photodetector, fixed at a preset azimuth angle, and allowing only a linearly polarized component of the reflected parallel beam in a preset direction to pass through. Photons, the azimuth angles of the fixed polarizer and the fixed analyzer, and the uniform rotation angular velocities of the uniform rotation polarizer and the uniform rotation analyzer are controlled, and the spectral radiant flux measured by the photodetector is measured. a computing device for analyzing the exposure value and calculating the optical properties of the test piece, wherein the fixed polarizer and the fixed analyzer are integrated as one linear polarizer, and the constant velocity rotating polarizer and the A constant rotation analyzer can be integrated as one constant rotation linear polarizer.

At this time, the normal incidence ellipsometer may integrate the light splitter, the fixed polarizer, and the fixed analyzer into one light splitting linear polarizer. Also, at this time, the light splitting linear polarizer may be a Wollaston prism.

In addition, the photodetector is selected from pixels or binned pixels for wavelength bands respectively designated by a spectroscope including CCD, CMOS, or photodiode array elements in which pixels are arranged in a linear or two-dimensional planar structure. It may be at least one. Also, at this time, the photodetector may be one spectroscope, or a set of spectroscopes consisting of an s-polarization spectroscope and a p-polarization spectroscope, each of which is a pixel or binned pixel for each designated wavelength band. may be at least one selected from

Alternatively, the photodetector element may be a single point photodetector including a PMT and a photodiode when the light source is a single wavelength light source device. The single-wavelength light source device may be at least one selected from a gas laser and a laser diode.

Alternatively, the photodetector is one selected from an imaging photodetector including a color filter that transmits light in a designated wavelength band and a CCD or CMOS in which pixels are arranged in a two-dimensional planar structure. It may be a pixel.

In addition, the vertical incidence ellipsometer includes a hollow shaft stepping motor for adjusting the azimuth angle of the fixed polarizer and the fixed analyzer, and the constant rotation polarizer and the constant rotation analyzer are rotated at constant speed. A constant velocity rotating hollow shaft motor for angular velocity adjustment may be provided.

Further, the computing device calculates a Fourier coefficient value for a spectral radiant flux waveform from the exposure amount value of the spectral radiant flux of light measured from the photodetector, and calculates the Mueller matrix component value of the test piece from the Fourier coefficient value. , and a computing unit that analyzes and calculates optical property values of the test piece from the Mueller matrix component values, and a hollow shaft stepping motor that remotely controls the azimuth angles of the fixed polarizer and the fixed analyzer , a controller for remotely controlling the constant rotation angular velocities of the constant rotation polarizer and the constant rotation analyzer using a constant rotation hollow shaft motor; a storage unit for storing calculated values that are the Fourier coefficient values and the Mueller matrix component values, and analytical values that are optical physical property values of the test piece; and an output unit that outputs the measured values, the calculated values, and the analytical values. can include

Further, the light source is at least selected from a Xenon lamp, a Tungsten-Halogen lamp, a Deuterium lamp, a Laser Driven Light Source, a gas laser, and a laser diode. One or the light emitted from these can be transmitted through an optical fiber.

Also, the normal incidence ellipsometer may include a shielding booth for shielding the light path from the outside atmosphere, and a gas supply device connected to the shielding booth for supplying an inert gas. At this time, the inert gas may be nitrogen gas or argon gas.

The normal incidence ellipsometer also includes focusing optics disposed between the constant velocity rotating polarizer and the specimen for converging the incident parallel beam to focus on a localized region of the specimen. be able to. At this time, the focusing optical system is one selected from at least one mirror, at least one lens, or a set of at least one mirror and at least one lens for chromatic aberration correction for the wavelength of the light band. good too. Also, at this time, the focusing optical system may be coated with a single thin film or multiple thin films on the mirror or the lens in order to improve transmission or reflection efficiency.

The normal incidence ellipsometer further comprises a test strip storage container for storing and storing a plurality of the test strips, and taking out the plurality of test strips from the test strip storage container one by one according to a preset rule. A test strip transport system may be included that includes a test strip transport device that is placed in a test strip holder of a normal incidence ellipsometer and returns the test strip after measurement to an initial position in the test strip storage container.

In addition, the vertical incidence ellipsometer includes an alignment laser that emits light for aligning the test piece, an alignment optical system that causes the light emitted from the alignment laser to enter the test piece in a preset direction, and the test piece. A test strip alignment system may be included that includes an alignment photodetector that receives light reflected from and reflected by the strip to determine the position of the test strip.

In addition, the normal incidence ellipsometer may include an anti-vibration system provided under the normal incidence ellipsometer to prevent the influence of vibration of the measurement environment.

In addition, the normal incidence ellipsometer may include a constant temperature device or a cooling device for maintaining or cooling the temperature of the environment for measurement in order to prevent measurement errors from occurring due to temperature changes.

A method for measuring optical properties of a test piece using a normal incidence ellipsometer according to the present invention is a method for measuring optical properties of a test piece using a vertical incidence ellipsometer as described above. a test strip mounting step in which the test strip is mounted and aligned in a test strip holder of the normal incidence ellipsometer; an azimuth movement step of moving the fixed polarizer and the fixed analyzer to a set azimuth angle by the computer; an exposure measurement step of measuring an exposure value of the spectral radiant flux of the reflected parallel beam due to a change in azimuth; a Mueller matrix component calculation step in which Mueller matrix component values of the specimen are calculated from the Fourier coefficient values by the computing device; and a test strip photophysical property analysis step in which photophysical property values of the test strip are analyzed and calculated.

At this time, the optical property may be at least one selected from interface property, thin film thickness, complex refractive index, nano-shape, anisotropic property, surface roughness, composition ratio, and crystallinity.

According to the present invention, in constructing a normal incidence ellipsometer, by using a linear polarizer with no wavelength dependence as a device for analyzing the polarization state, the It has a great effect of solving various problems at once. More specifically, the present invention has the effect of simplifying the equipment calibration procedure by eliminating the wavelength dependence, thereby greatly reducing the occurrence of errors arising from the complicated equipment calibration procedure. has the effect of Conventionally, in order to expand the measurement wavelength range, it was necessary to newly develop a compensator suitable for it. It has the effect of being free. Further, according to the present invention, by expanding the measurement wavelength region, the effect of improving the measurement reliability of the vertical incidence ellipsometer is obtained.

1 is a schematic diagram of a conventional single compensator-rotational normal incidence ellipsometer; FIG. 1 is a schematic diagram of a conventional dual compensator-rotational normal incidence ellipsometer; FIG. 1 is a schematic diagram of a linear polarizer-rotational normal incidence ellipsometer according to a first embodiment of the present invention; FIG. Fig. 2 is a schematic diagram of a linear polarizer-rotational normal incidence ellipsometer according to a second embodiment of the present invention; FIG. 3 is a schematic diagram of a linear polarizer-rotational normal incidence ellipsometer according to a third embodiment of the present invention; 1 is a flow chart showing a method for measuring optical physical properties of a test piece using the linear polarizer-rotational normal incidence ellipsometer of the present invention.

Hereinafter, a vertical incidence ellipsometer having the above-described structure and a method for measuring optical properties of a test piece using the same according to the present invention will be described in detail with reference to the accompanying drawings.

[Basic Configuration of the Vertical Incidence Ellipsometer of the Present Invention]
The present invention overcomes the above-described conventional problems by using a wavelength-independent linear polarizer instead of a wavelength-dependent compensator. Various embodiments of normal incidence ellipsometers of the present invention are illustrated in FIGS. 3-5, and each embodiment is described in more detail below. The normal incidence ellipsometer of the present invention is basically composed of a light source, a light splitter, a fixed polarizer, a uniform rotating polarizer, a photodetector, a uniform rotating analyzer, a fixed analyzer, and a computer. including equipment. Each part will be described below.

The Light Source includes a Collimator and serves to emit an Incident Collimated Beam towards the specimen. At this time, the light source is selected from a xenon lamp, a tungsten-halogen lamp, a deuterium lamp, a laser driven light source, a gas laser, and a laser diode. There may be at least one, or the light emitted from these may be transmitted through an optical fiber.

The beam splitter is disposed between the light source and the test piece and serves to direct a portion of the incident parallel beam perpendicular to the plane of the test piece.

The fixed polarizer is disposed between the light splitter and the test piece and fixed at a preset azimuth angle to convert the incident parallel beam into a linearly polarized component in a preset direction. only pass through. At this time, the azimuth angle of the fixed polarizer is not always fixed, and the fixed polarizer itself is movable so that it can be adjusted to a desired azimuth angle when the test piece is to be measured, In this case, the term "fixed" is used because it is fixed during measurement. At this time, the fixed polarizer may be provided with a hollow shaft stepping motor to adjust the azimuth angle of the fixed polarizer.

The Constantly Rotating Polarizer is disposed between the fixed polarizer and the test piece and rotates at a constant speed to change the polarization state of the incident parallel beam according to the constant rotation frequency. Plays a role of regular modulation. At this time, the uniform rotation polarizer may be provided with a uniform rotation hollow shaft motor in order to adjust the uniform rotation angular velocity of the uniform rotation polarizer.

The photodetector receives the reflected collimated beam reflected from the test piece and measures the exposure of spectral radiant flux . At this time, the photodetector is selected from pixels or binned pixels for wavelength bands respectively designated by a spectroscope including CCD, CMOS, or photodiode array elements in which pixels are arranged in a linear or two-dimensional planar structure. may be at least one. Also, at this time, the photodetector may be one spectroscope, or a set of spectroscopes consisting of an s-polarization spectroscope and a p-polarization spectroscope, each of which is a pixel or binned pixel for each designated wavelength band. may be at least one selected from

More specifically, when the light source uses white light, a spectroscope can be used as a means for detecting light, but what actually detects the light is provided within the spectroscope. each pixel or binned group of pixels in the photodetector array. That is, rather than the spectroscope itself, it should be understood that each pixel or each binned pixel group serves as a single photodetector.

Alternatively, the photodetector element may be a single point photodetector including a PMT and a photodiode when the light source is a single wavelength light source device. The single-wavelength light source device may be at least one selected from a gas laser and a laser diode. Alternatively, the photodetector may be one pixel selected from imaging photodetectors including CCD or CMOS in which pixels are arranged in a two-dimensional planar structure. At this time, if the light source is a single-wavelength light source device, no additional components are required. Alternatively, color filters for transmitting light of a designated wavelength band may be further provided between the photodetecting elements (composed of pixels of an imaging photodetector including CMOS).

The photodetector maintains a standby state before an external trigger is transmitted, and performs measurement when an external trigger is transmitted. In the case of one pixel or binned pixel (pixel binning) selected from an integral photodetector, a method of outputting or temporarily storing the exposure value during the integration time specified for each photodetector and the photodetector element is a non-integrating photodetector, such as a photodetector including a PMT and a photodiode, the exposure value during a very short integration time, i.e. approximately the spectrum of light It can operate by outputting the radiant flux value or by temporarily storing it.

The Constantly Rotating Analyzer is disposed between the test piece and the photodetector and rotates at a constant speed to change the polarization state of the reflected parallel beam according to the constant rotation frequency. Plays a role of regular modulation. Here, a different name is used for the constant velocity rotation analyzer because the role of the constant velocity rotation analyzer is different from that of the constant velocity rotation polarizer described above. are embodied by different parts, but in the case of the vertical incidence type, they can be substantially embodied by one part (in this way, the vertical incidence type ellipsometer is more suitable than the oblique incidence type ellipsometer. The point that the device can be made more compact was mentioned above). That is, in the present invention, the constant velocity rotating polarizer and the constant velocity rotating analyzer are integrated as one constant velocity rotating linear polarizer.

The Fixed Analyzer is disposed between the constant velocity rotating analyzer and the photodetector element and is fixed at a preset azimuth angle to provide a preset direction of the reflected parallel beam. It plays the role of passing only the linearly polarized light component. As with the fixed polarizer, the fixed analyzer itself can be moved, but is fixed during measurement, hence the term "fixed". Also, similar to the constant rotation polarizer-the constant rotation analyzer, the fixed polarizer and the fixed analyzer are integrated as one linear polarizer. Furthermore, the light splitter, the fixed polarizer and the fixed analyzer can be integrated as one light splitting linear polarizer so that the device can be further miniaturized and integrated. In this case, the light splitting linear polarizer may consist of a Wollaston prism.

The computer (processor) controls the azimuth angles of the fixed polarizer and the fixed analyzer, the uniform rotational angular velocities of the uniform rotational polarizer and the uniform rotational analyzer, and measures the It analyzes the exposure value of Spectral Radiant Flux to calculate the photophysical properties of the test piece. More specifically, the computing device includes a computing unit that performs various computations, a control unit that controls the driving of the various components described above, a storage unit that stores values necessary for computation, and outputs analysis results. and an output to The arithmetic unit calculates a Fourier coefficient value for a spectral radiant flux waveform from the exposure amount value of the spectral radiant flux of light measured from the photodetector, and calculates the Fourier coefficient value from the Fourier coefficient value. It is possible to calculate the Mueller Matrix component values of the test piece, and analyze and calculate the optical property values of the test piece from the Mueller Matrix component values. The control unit remotely controls the azimuth angle of the fixed polarizer and the fixed analyzer using a hollow shaft stepping motor, and controls the azimuth angles of the constant velocity rotating polarizer and the constant velocity rotating analyzer. The constant rotational angular velocity (Angular Velocity) can be remotely controlled using a constant rotational hollow shaft motor. The storage unit stores values necessary for the calculation performed by the calculation unit, that is, the exposure amount value (measurement value) measured from the photodetector, the Fourier coefficient value for the spectral radiant flux waveform, and the Mueller matrix components of the test piece. Stores the value (calculated value) and optical property value (analysis value) of the test piece. The output section outputs the measured values, the calculated values, and the analyzed values in a form desired by the user, such as a screen or printed matter, using a monitor, a printer, or the like.

Further, the normal incidence ellipsometer of the present invention further includes a shielding booth for shielding the light path from the external atmosphere and a gas supply device connected to the shielding booth for supplying an inert gas such as nitrogen gas or argon gas. can be done. By doing so, it is possible to effectively prevent the problem that light of a specific wavelength is absorbed by moisture, oxygen, etc. as described above, and finally to smoothly expand the measurement wavelength range.

The vertical incidence ellipsometer of the present invention having such a configuration differs from the conventional ellipsometer shown in FIG. 1 or FIG. 2 by using a constant velocity rotating linear polarizer instead of a constant velocity rotating compensator. The compensator used in the conventional ellipsometer has wavelength dependence in which the phase delay value of the compensator changes for each wavelength as described above, which requires a complicated calibration procedure. There was a problem that an error occurred between them. However, according to the present invention, by eliminating the compensator itself and instead using a linear polarizer with no wavelength dependence, the calibration procedure itself can be greatly simplified, resulting in error generation. It goes without saying that the problem of is also eliminated from the beginning.

Specifically, in the normal incidence ellipsometer of the present invention, the linear polarizer (the role of the fixed polarizer and the fixed analyzer) has a polarization state error that can be generated by the light source and the light splitter on the incident parallel beam axis. on the reflected parallel beam axis serves to eliminate polarization state errors that may be generated by the light splitter and detection optics. In addition, the uniform rotation linear polarizer (roles of the uniform rotation polarizer and the uniform rotation analyzer) regularly modulates the polarization states of the incident parallel beam and the reflected parallel beam by the uniform rotation frequency. play a role As described above, the vertical incidence ellipsometer of the present invention does not use a polarizing optical element that is wavelength dependent, so the equipment calibration procedure is very simple, matching between equipment is easy, and measurement reliability is improved. The wavelength range can be easily extended to the optical band.

[Additional Configuration of the Vertical Incidence Ellipsometer of the Present Invention]
The normal incidence ellipsometer of the present invention further includes additional features such as focusing optics, specimen transport system, specimen alignment system, anti-vibration system, constant temperature device or cooling device to improve measurement accuracy and user convenience. can contain.

When the normal incidence ellipsometer is used in a field such as the semiconductor industry, the size of the area to be measured on the test piece is as small as several tens of micrometers, so the incident light is applied smoothly to the local area of the test piece. The focusing optics may optionally be provided in the front path of the specimen so as to focus on the . That is, the focusing optics are placed between the constant-rotating polarizer and the specimen and serve to focus the incident parallel beam so that a localized region of the specimen is focused. Specifically, the focusing optic comprises one selected from at least one mirror, at least one lens, or a set of at least one mirror and at least one lens for chromatic aberration correction for optical band wavelengths. can become At this time, it is preferable that the mirror or the lens is coated with a single thin film or multiple thin films in order to improve transmission or reflection efficiency.

On the other hand, when the vertical incidence ellipsometer is used in the field of the semiconductor industry, it is important to measure a large number of wafer test pieces within a short period of time. obtain. Specifically, the test strip transport system includes a test strip storage container for storing and storing a plurality of the test strips, and a plurality of the test strips from the test strip storage container in order according to a preset rule. a test strip transporter for removing the test strips one by one, placing them in the test strip holder of the normal incidence ellipsometer, and returning the test strips after measurement to the initial position in the test strip storage container. At this time, the test piece holder is arranged so that the test piece can be freely aligned and the measurement position can be smoothly changed. It can consist of a 6 degree of freedom system including a rotation function.

In addition, the test strip alignment system may be provided to more accurately and quickly align the test strips during the measurement process in such a short time. Specifically, the test piece alignment system includes an alignment laser that emits light for aligning the test piece, and an alignment optical system that causes the light emitted from the laser to be incident on the test piece in a preset direction. and an alignment photodetector that receives the light incident on and reflected from the test piece and determines the position of the test piece.

Furthermore, the anti-vibration system can be provided at the bottom of the normal incidence ellipsometer so as to prevent the influence of vibrations of the measurement environment. Further, the light source, the polarizing light element, the test piece, and the light detection element are provided with the constant temperature device to maintain the temperature of the measurement environment so as to prevent the occurrence of measurement errors due to temperature changes, Alternatively, it is preferable that the photodetector is provided with the cooling device for cooling.

Various Embodiments of the Normal Incidence Ellipsometer of the Present Invention
FIG. 3 illustrates a schematic diagram of a linear polarizer-rotational normal incidence ellipsometer according to a first embodiment of the present invention. The linear polarizer-rotating normal incidence ellipsometer 100 of the first embodiment of the present invention includes a light source 101, a light splitter 102, a linear polarizer 103, a hollow shaft stepping motor 103m, and a constant velocity rotating linear polarizer 104. , a uniform rotary hollow shaft motor 104m, a photodetector 105, and a computing device 106. In the first embodiment, the linear polarizer 103 in the description of the basic configuration plays both roles of the fixed polarizer and the fixed analyzer, and the constant velocity rotating linear polarizer 104 is the constant velocity It functions as both a rotating polarizer and the uniform rotating analyzer.

Furthermore, the normal incidence ellipsometer 100 of the first embodiment can include a shielding booth 107 for extending the measurement wavelength range and a gas supply device 108, as described above, and can also Focusing optics 109 may be included to provide smooth focusing on the .

FIG. 4 illustrates a schematic diagram of a linear polarizer-rotational normal incidence ellipsometer according to a second embodiment of the invention. The linear polarizer-rotating normal incidence ellipsometer 200 of the second embodiment of the present invention includes a light source 201, a light splitting linear polarizer 203, a constant velocity rotating linear polarizer 204, a constant velocity rotating hollow shaft motor 204m, It includes a photodetector 205 and a computing device 206 . In the second embodiment, the light splitting linear polarizer 203 serves as the light splitter, the fixed polarizer, and the fixed analyzer in the description of the basic configuration, thereby further miniaturizing the equipment. and can be integrated.

Although FIG. 4 does not show the shielding booth, gas supply, focusing optics, etc., the second embodiment of FIG. It goes without saying that it is possible to prepare

FIG. 5 illustrates a schematic diagram of a linear polarizer-rotational normal incidence ellipsometer according to a third embodiment of the invention. The linear polarizer-rotating normal incidence ellipsometer 300 of the third embodiment of the present invention comprises a light source 301, a light splitter 302, a light splitting linear polarizer 303, a constant rotating linear polarizer 304, and a constant rotating It includes a hollow shaft motor 304m, an s-polarized light detector 305s, a p-polarized light detector 305p, and a computing device 306. In the third embodiment, the s-polarization photodetector 305s and the p-polarization photodetector 305p serve as the photodetectors in the description of the basic configuration. On the other hand, in the third embodiment, the light splitting linear polarizer 303 functions as the light splitter, the fixed polarizer, and the fixed analyzer in the description of the basic configuration. At this time, as shown in FIG. 5, the light splitter 302 is further provided to form an optical path for directing the light emitted from the light source 301 toward the test piece 1000 .

Furthermore, in the linear polarizer-rotational vertical incidence ellipsometer of the present invention, the rotation of the uniform rotation linear polarizer by the uniform rotation hollow shaft motor of the polarized optical element is one selected from uniform rotation or step rotation. There may be.

[Principle of measurement of optical physical properties of test piece using vertical incidence ellipsometer of the present invention]
The principle of optical physical property measurement of a test piece using the vertical incidence ellipsometer of the present invention as described above will be described in detail below. The azimuth angles for the fixed polarizer, the constant rotation polarizer, the constant rotation analyzer, and the fixed analyzer used in the normal incidence ellipsometer of the present invention are the transmission axis of the linear polarizer with the fixed polarizer, the constant rotation The positions of the transmission axis of the linear polarizer with the polarizer, the transmission axis of the linear polarizer with the constant velocity rotating analyzer, and the transmission axis of the linear polarizer with the fixed analyzer are each determined based on the position of the arbitrarily selected reference axis.

Therefore, the value of the spectral radiant flux at the polychromatic wavelength measured by the photodetector at time t in the error-free ideal linear polarizer-rotating normal incidence ellipsometer is given by the following general can be expressed as an equation for a typical waveform.

In the linear polarizer-rotating normal incidence ellipsometer, it is very important to accurately measure the Fourier coefficients of the spectral radiant flux waveform using the photodetector. State-of-the-art real-time spectroscopic ellipsometers use a CCD (Charge Coupled Device) or PD array (Photo Diode array) as a photodetector that can collect the spectrum of Fourier coefficients as quickly as possible for highly accurate real-time measurements. is doing. Each pixel or each binning pixel group of the CCD or PD array serves as the one photodetection element. The output signal of a CCD or PD array is called an integrating photodetector because it is proportional not only to the spectral radiant flux but also to the integration time.

The data measurement process of CCD or PD array can be divided into frame acquisition and frame reading process. That is, for constant rotational angular velocity

The formula for the measured exposure dose from formulas (2) and (3) is derived in the following form.

Applying the Discrete Fourier Transform to the measured exposure dose as in equation (4), the result is the same as that obtained by the least squares method as described above, but with the The representation method has the advantage of being more concise as follows.

In a typical ellipsometer configuration, a collimated beam emitted from a Light Source (LS) passes through a Polarization State Generator (PSG) and is reflected by a specimen before being reflected by a Polarization State Analyzer (PSG). Analyzer (PSA) and incident on a photodetector element (PDE), the spectral radiant flux is converted into an electrical signal. In particular, the rotatable polarization element used in the optical element-rotating spectroscopic ellipsometer is divided into a linear polarizer and a compensator, which are the optical element- They are separately arranged in the polarization state generator and the polarization state analyzer according to the type of rotating spectroscopic ellipsometer. At least one polarizing optical element among the rotatable polarizing optical elements in the optical element-rotating spectroscopic ellipsometer must rotate at a constant speed at each constant frequency, and the other rotatable polarizing optical elements , are stopped at their respective designated positions. The azimuth angle of the rotatable polarized light element can be remotely controlled by the hollow shaft motor, and the rotatable polarized light element is positioned at the azimuth reference point of the hollow shaft motor, i.e., the index origin. Each characteristic axis can be at a different position. In order for the measurement to be performed correctly, the azimuthal position of the characteristic axis of the rotatable polarizing optical element from an arbitrarily defined reference axis should be known. Using an existing well-known calibration method, the azimuth position of the characteristic axis of the polarizing optical element can be found in the reference axis coordinate system, respectively. Therefore, transforming equation (2) with respect to the reference axis coordinate system gives the following.

A data reduction function in the ellipsometer is used to extract the polarization ellipsometric parameters of the specimen from the corrected Fourier coefficients, so a data reduction method suitable for the optical element-rotating spectroscopic ellipsometer used is provided. Searching is very important. According to the Stokes representation, the Stokes vector of the incident light wave to pass through the polarization state generator is

The Stokes vector of the light wave incident on the photodetector for the quasi-monochromatic light wave can be described as follows.

Depending on the total number of linear equations used for data reduction, solutions to the system of linear equations are given in Unique or Overdetermined form. The above data reduction equations are applicable to all forms of optical element-rotational ellipsometers.

We introduce a generalized data reduction method that can obtain the specimen ellipsometric parameters from all corrected Fourier coefficients. Let the column vector of corrected Fourier coefficients be

の値を得ると、式（２０）を使用して補正されたフーリエ係数の値から試験片のミュラー行列の成分を直接計算することが可能である。ここで強調したいことは、前記のような方法で計算されたミュラー行列成分に対するベクトルの解は、非等方性試験片の場合にも適用可能であるということである。 Therefore, from the measurement results using a reference test piece whose optical properties are well known or the measurement results on a straight line without a test piece, Equation (19) is obtained for each wavelength.

Once we have the value of , it is possible to directly calculate the elements of the Mueller matrix for the specimen from the values of the corrected Fourier coefficients using equation (20). It should be emphasized here that the vector solutions for the Mueller matrix elements computed in the manner described above are also applicable to the case of anisotropic specimens.

Measure the spectral radiant flux of light as described above, establish an optical theoretical formula for the test piece, and use a number of unknown parameters for the area set for the established theoretical formula to determine the Mueller By calculating the data of the matrix components and optimizing the data using the method of least squares or the like, it is possible to estimate the value of the optical physical property to be obtained for the test piece. That is, other physical properties can be analyzed from the Mueller matrix. Thus, the linear polarizer-rotating normal incidence ellipsometer according to the embodiment of the present invention can determine from the measured Fourier coefficients or the measured Mueller matrix components the interfacial properties of the specimen, thin film thickness, complex refractive index, nano Various physical properties such as shape, anisotropic properties, surface roughness, composition ratio, crystallinity, etc. can be analyzed, and the analysis results are used in measuring equipment for semiconductor device process, flat panel display process, solar light, etc. It can be used for device measurement equipment, thin film optical measurement equipment, biosensors or gas sensors. Specifically, a physical property analysis method for a very complicated analysis method such as nanopattern shape measurement in the linear polarizer-rotational vertical incidence ellipsometer according to the embodiment of the present invention will be described below. Obtain measurement data of Fourier coefficients or Mueller matrix components for the test piece to be measured first, establish an optical theoretical formula for the test piece, Obtain the data of the Fourier coefficients or Mueller matrix elements calculated using the values of the unknown parameters, make a continuous function for the unknown parameters on the calculated data, and apply the continuous function to the measured data at least two times. By optimizing using multiplication, the physical properties of the specimen can be obtained. In such a case, the ellipsometer of the present invention uses a high-performance parallel computer, RCWA ( It can include a high-capacity, high-speed computing system composed of (rigorous coupled-wave analysis) algorithm-based analysis software and mass data storage.

[Method for measuring optical properties of test piece using normal incidence ellipsometer of the present invention]
FIG. 6 is a flow chart showing a method for measuring the optical properties of a test piece using the linear polarizer-rotational vertical incidence ellipsometer of the present invention. . As shown in FIG. 6, the method for measuring the optical physical properties of a test piece using a vertical incidence ellipsometer according to the present invention includes a test piece mounting step S10, an azimuth angle selection step S20, an azimuth angle movement step S30, It can include an exposure amount measurement step S40, a Fourier coefficient calculation step S50, a Mueller matrix component calculation step S60, and a specimen optical property analysis step S70.

In the test piece mounting step S10, the test piece whose optical properties are to be measured is mounted and aligned on the test piece holder of the normal incidence ellipsometer. In the azimuth angle selection step S20, the azimuth angle values of the fixed polarizer and the fixed analyzer are selected by the computing device. In the azimuth angle movement step S30, the computer device moves the fixed polarizer and the fixed analyzer to a set azimuth angle. In the exposure amount measurement step S40, the exposure amount value of the reflected parallel beam due to the change in the azimuth angle of the constant velocity rotation polarizer and the constant velocity rotation analyzer is measured by the photodetector. In the Fourier coefficient calculation step S50, the Fourier coefficient value of the spectral radiant flux waveform is calculated from the exposure amount value by the computer device. In the Mueller matrix component calculation step S60, the Mueller matrix component values of the test piece are calculated from the Fourier coefficient values by the computer equipment. In the test piece photophysical property analysis step S70, the computer analyzes and calculates the photophysical property values of the test piece from the Mueller matrix component values.

It goes without saying that the present invention is not limited to the above-described embodiments, and that the scope of application is diverse. It goes without saying that anyone who has knowledge of the above can implement various modifications.

According to the present invention, by using a wavelength-independent linear polarizer as the device for analyzing the polarization state in constructing a normal-incidence ellipsometer, the Various problems such as complicated equipment calibration procedures and resulting error generation can be solved. In addition, according to the present invention, the measurement wavelength range can be expanded more freely than in the prior art, thereby improving the measurement reliability of the vertical incidence ellipsometer.

10 (Conventional) Single Compensator-Rotational Normal Incidence Ellipsometer 11 Light Source 12 Light Splitter 13 Linear Polarizer 14 Constant Velocity Rotation Compensator 15 Spectrograph 16 Computer L10a Incident Collimated Beam Emitted by Light Source L10b On Test Piece Incident incident parallel beam L10c Reflected parallel beam reflected by the specimen L10d Reflected parallel beam incident on the spectrometer 20 (conventional) double compensator-rotational normal incidence ellipsometer 21 light source 22 light splitter 23 linear polarizer 24a th 1 constant velocity rotation compensator 24aw 1st wave plate 24am 1st constant velocity rotation hollow shaft motor 24b 2nd constant velocity rotation compensator
24bw Second wave plate 24bm Second constant velocity rotating hollow shaft motor 25 Spectrometer 26 Computer equipment 27 Shielding booth 28 Gas supply device L20a Incident parallel beam emitted by light source L20b Incident parallel beam incident on test piece L20c By test piece Reflected Reflected Parallel Beam L20d Reflected Parallel Beam Entering Spectrometer 100 Linear Polarizer-Rotating Normal Incidence Ellipsometer of First Embodiment of the Invention 101 Light Source 102 Light Splitter 103 Linear Polarizer 103m Hollow Shaft Stepper Motor 104 Constant Velocity Rotating linear polarizer 104m Uniform rotating hollow shaft motor 105 Photodetector 106 Computer equipment 107 Shielding booth 108 Gas supply device 109 Focusing optics L100a Incident parallel beam emitted by light source L100b Incident parallel beam incident on test piece L100c Test Reflected parallel beam reflected by piece L100d Reflected parallel beam incident on photodetector element 200 Linear polarizer of the second embodiment of the invention - rotated normal incidence ellipsometer 201 light source 203 light splitting linear polarizer 204 constant velocity rotating linear polarizer 204m Constant velocity rotating hollow shaft motor 205 Photodetector 206 Computing equipment L200a Incident parallel beam emitted by light source L200d Reflected parallel beam incident on photodetector 300 Linear polarizer of the third embodiment of the present invention - rotating vertical incidence Ellipsometer 301 light source 302 light splitter 303 light splitting linear polarizer 304 uniform rotary linear polarizer 304m uniform rotary hollow shaft motor 305s s-polarized light detector 305p p-polarized light detector 306 computer L300a emitted by light source Incident parallel beam L300s Reflected parallel beam incident on s-polarized photodetector L300p Reflected parallel beam incident on p-polarized photodetector 1000 Specimen

Claims (21)

a light source that includes collimating optics and emits an incident parallel beam toward the specimen;
a light splitter positioned between the light source and the test piece for directing a portion of the incident parallel beam perpendicular to the plane of the test piece;
a fixed polarizer disposed between the light splitter and the test piece, fixed at a preset azimuth angle, and allowing the incident parallel beam to pass only a linearly polarized component in a preset direction;
a constant velocity rotating polarizer disposed between the fixed polarizer and the test piece and rotating at a constant velocity to regularly modulate the polarization state of the incident parallel beam according to the constant velocity rotation frequency;
a photodetector for receiving the reflected parallel beam reflected from the test piece and measuring the exposure amount of the spectral radiant flux ;
a constant velocity rotating analyzer disposed between the test piece and the photodetector, rotating at a constant velocity to regularly modulate the polarization state of the reflected parallel beam according to the constant velocity rotation frequency;
a fixed analyzer disposed between the constant velocity rotating analyzer and the photodetector, fixed at a preset azimuth angle, and allowing only a linearly polarized component of the reflected parallel beam in a preset direction to pass through;
The azimuth angles of the fixed polarizer and the fixed analyzer, the uniform rotational angular velocities of the uniform rotational polarizer and the uniform rotational analyzer, and the exposure value of the spectral radiant flux measured by the photodetector. and a computer that analyzes and calculates the optical properties of the test piece,
The fixed polarizer and the fixed analyzer are integrated as one linear polarizer, and the constant-rotational polarizer and the constant-rotational analyzer are integrated as one constant-rotational linear polarizer. , normal incidence ellipsometer. The normal incidence ellipsometer,
2. The normal incidence ellipsometer of claim 1, wherein said light splitter, said fixed polarizer and said fixed analyzer are integrated as one light splitting linear polarizer. The light-splitting linear polarizer is
3. A normal incidence ellipsometer according to claim 2, characterized in that it is a Wollaston prism. The photodetector is
Pixels are at least one selected from pixels for each designated wavelength band or binned pixels in a spectroscope including CCD, CMOS or photodiode array elements arranged in a linear or two-dimensional planar structure. 2. The normal incidence ellipsometer of claim 1, wherein . The photodetector is
One spectroscope, or at least one selected from pixels or binned pixels for each designated wavelength band in a spectroscope set consisting of an S-polarization spectroscope and a P-polarization spectroscope. 5. A normal incidence ellipsometer as claimed in claim 4. The photodetector is
In the case of a single-wavelength light source device in which the light source is at least one selected from a gas laser and a laser diode, the light source device is configured as a single-point photodetector including a PMT and a photodiode. Normal incidence ellipsometer as described. The photodetector is
2. The normal incidence ellipsometer according to claim 1, wherein the pixel is one pixel selected from imaging photodetectors including CCD or CMOS arranged in a two-dimensional planar structure. The normal incidence ellipsometer,
the fixed polarizer and the fixed analyzer are provided with hollow shaft stepping motors for azimuth adjustment;
2. The vertical incidence ellipsometer as claimed in claim 1, further comprising a constant rotation hollow shaft motor for adjusting the constant rotation angular velocities of the constant rotation polarizer and the constant rotation analyzer. The computing equipment is
calculating a Fourier coefficient value for a spectral radiant flux waveform from the exposure value of the spectral radiant flux of light measured from the photodetector, calculating the Mueller matrix component values of the test piece from the Fourier coefficient value, and calculating the Mueller matrix a calculation unit that analyzes and calculates optical property values of the test piece from the component values;
The azimuth angles of the fixed polarizer and the fixed analyzer are remotely controlled using a hollow shaft stepping motor, and the uniform rotation angular velocities of the uniform rotation polarizer and the uniform rotation analyzer are controlled by a uniform rotation hollow shaft motor. a control that is remotely controlled using
a storage unit for storing measured values that are exposure values of the spectral radiant flux , calculated values that are the Fourier coefficient values and the Mueller matrix component values, and analytical values that are optical physical property values of the test piece;
2. A normal incidence ellipsometer according to claim 1, further comprising an output section for outputting said measured values, said calculated values and said analyzed values. The light source is
at least one selected from a xenon (XENON) lamp, a tungsten (TUNGSTEN)-halogen (HALOGEN) lamp, a deuterium (DEUTERIUM) lamp, a laser driven light source (LASER DRIVEN LIGHT SOURCE), a gas laser, a laser diode; 10. A normal incidence ellipsometer according to claim 9, characterized in that the light emitted therefrom is transmitted through an optical fiber. The normal incidence ellipsometer,
a shielding booth that shields the light path from the outside atmosphere;
2. A normal incidence ellipsometer according to claim 1, further comprising a gas supply device connected to said shielding booth for supplying an inert gas. The inert gas is
12. Normal incidence ellipsometer according to claim 11, characterized in that it is nitrogen gas or argon gas. The normal incidence ellipsometer,
4. A focusing optic disposed between said constant velocity rotating polarizer and said specimen for converging said incident parallel beam so as to focus on a localized region of said specimen. 2. A normal incidence ellipsometer according to claim 1. The focusing optical system is
14. The method according to claim 13, characterized in that it is one selected from at least one mirror, at least one lens, or a set of at least one mirror and at least one lens for chromatic aberration correction for optical band wavelengths. Normal incidence ellipsometer as described. The focusing optical system is
15. The normal incidence ellipsometer of claim 14, wherein the mirror or lens is coated with a single thin film or multiple thin films for improved transmission or reflection efficiency. The normal incidence ellipsometer,
A test strip storage container for storing and storing a plurality of the test strips, and a test strip holder for the normal incidence ellipsometer for sequentially taking out the plurality of test strips from the test strip storage container one by one according to a preset rule. 2. The normal incidence ellipsometer of claim 1, further comprising a test strip transport system including a test strip transport device for returning the test strip after measurement to an initial position in the test strip storage container. . The normal incidence ellipsometer,
An alignment laser that emits light for aligning a test piece, an alignment optical system that makes the light emitted from the alignment laser incident on the test piece in a preset direction, and light that is incident on and reflected by the test piece 2. The normal incidence ellipsometer of claim 1, including a specimen alignment system including an alignment photodetector for receiving .rho. to determine the position of said specimen. The normal incidence ellipsometer,
2. The normal incidence ellipsometer of claim 1, further comprising an anti-vibration system provided at the bottom of the normal incidence ellipsometer to prevent the influence of vibration of the measurement environment. The normal incidence ellipsometer,
2. The normal incidence ellipsometer according to claim 1, further comprising a constant temperature device or a cooling device for maintaining or cooling the measurement environment temperature to prevent measurement errors from occurring due to temperature changes. A method for measuring optical properties of a test piece using the normal incidence ellipsometer according to claim 1,
a test piece mounting step in which the test piece whose optical properties are to be measured is mounted and aligned on a test piece holder of the normal incidence ellipsometer;
an azimuth selection step in which azimuth angle values of the fixed polarizer and the fixed analyzer are selected by the computing device;
an azimuth movement step of moving the fixed polarizer and the fixed analyzer to a set azimuth angle by the computing device;
an exposure measuring step of measuring, by the photodetector, the exposure value of the spectral radiant flux of the reflected parallel beam due to changes in the azimuth angles of the constant velocity rotating polarizer and the constant velocity rotating analyzer;
a Fourier coefficient calculation step in which a Fourier coefficient value of the spectral radiant flux waveform is calculated from the exposure value of the spectral radiant flux by the computing device;
a Mueller matrix component calculation step in which the computing device calculates Mueller matrix component values for the specimen from the Fourier coefficient values;
and a test piece optical property analysis step in which the optical property values of the test piece are analyzed and calculated from the Mueller matrix component values by the computer. How to measure. The optical physical properties are
21. The perpendicular according to claim 20, characterized by at least one selected from interface properties, thin film thickness, complex refractive index, nano-shape, anisotropic properties, surface roughness, composition ratio, and crystallinity. A method for measuring the optical properties of a test piece using an incident ellipsometer.