JPH11101739A - Ellipsometry apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a rotary part and failures and miniaturize an apparatus, by measuring a polarization state of a reflecting light from a detection result of the reflecting light polarized in a plurality of directions by a plurality of polarizing means. SOLUTION: A light from a light source 10 is guided to an incident light system by an optical fiber 11. The light emitted from the optical fiber 11 is turned to parallel lights by a collimator lens 20. Linearly polarized parallel lights by a polarizer 21 are condensed to a surface of a sample 70 by a emergence lens 22. A reflecting light reflected at the sample 70 is turned to parallel lights by an incidence lens 30, and reflected towards a matching lens 33 by a transparent plate 31. The light passing the transparent plate 31 is separated to two polarization components by a polarizing beam splitter 32. The separated lights are brought in optical fibers 36-38 by matching lenses 33-35 and introduced to spectroscopes 40-42. The lights output from the spectroscopes 40-42 are detected respectively by photodetectors 50-52. Detection results of the photodetectors 50-52 are input to a controller 60 controlling the spectroscopes 40-42 and photodetectors 50-52.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ellipsometry apparatus for measuring a thickness and an optical constant of a thin film, that is, a refractive index and an absorptance with respect to a wavelength, based on a change in a polarization state due to reflection of light.

[0002]

2. Description of the Related Art According to the principle of this type of ellipsometer, when a sample is irradiated with any known polarization, the polarization state of reflected light is determined by the optical constant of the sample, the film thickness of the thin film on the sample surface, and the optical state. It is uniquely determined by a constant. Therefore, by measuring the polarization state of the reflected light, the thickness and the optical constant of the thin film on the sample surface are measured. Many measuring devices have been developed for this purpose.

FIG. 2 is a diagram showing the principle of a conventional ellipsometry device. FIG. 2 shows a widely used photoelectric photometric ellipsometer. This device comprises a light source 100, a polarizer 101, an analyzer 102 and a detector 10
Consists of three.

One of the conventional typical measuring methods using the above-mentioned ellipsometry apparatus is a rotary analyzer type. In this method, incident light is linearly polarized light having an azimuth angle suitable for a sample to be measured. The azimuth angle P of the polarizer 101 is adjusted so that At this time, the analyzer 102 is rotated, the light intensity of the detector 103 with respect to the azimuth A of the rotated analyzer 102 is measured at many points, and the polarization state of the reflected light is measured from the obtained waveform.

Then, the ratio of the reflectance of P-polarized light to the reflectance of S-polarized light, that is, the reflectance ratio ρ is obtained from the following equation (1) from the data obtained by measuring the reflected polarization, and the thin film is calculated by calculation. Find thickness and refractive index.

The reflectance ratio ρ = P-polarized light reflectance / S-polarized light reflectance (1) Alternatively, the azimuth A of the analyzer 102 is fixed, and the polarizer 1
The light intensity is measured by the detector 103 while rotating 01.

[0007]

In the above-mentioned conventional ellipsometry apparatus, the rotating part of the polarizer 101 and the analyzer 102 is essential. For this reason, there is a problem that the measurement time is limited, a problem that occurs due to the rotating portion, and a problem that the measuring device cannot be configured in a small size because the rotating portion needs to be configured. An object of the present invention is to provide an ellipsometry device that can be configured without a rotating part.

[0008]

In order to solve the above-mentioned problems and achieve the object, an ellipsometer according to the present invention is configured as follows. The ellipsometry device of the present invention
In an ellipsometry device that measures the state of the sample by measuring the polarization state of the reflected light from the sample, a plurality of polarizing means, each fixed and polarizing the reflected light,
A plurality of detecting means for detecting the reflected light polarized in a plurality of directions by the plurality of polarizing means; and a measuring means for measuring a polarization state of the reflected light from detection results of the plurality of detecting means. Have been.

[0009]

FIG. 1 is a diagram showing a configuration of an ellipsometry apparatus according to an embodiment of the present invention. In the ellipsometry apparatus shown in FIG. 1, light from a light source 10 is guided by an optical fiber 11 to an incident optical system. The light emitted from the optical fiber 11 is converted into parallel light by a collimator lens 20, and the parallel light is converted into linearly polarized light by a polarizer 21. The parallel light of the linearly polarized light is focused on the surface of the sample 70 to be measured by the exit lens 22.

The reflected light reflected on the surface of the sample 70 is converted into parallel light by the incident lens 30, and a specific polarization component of the reflected light is reflected by the transparent plate 31 toward the matching lens 33.
Further, the light transmitted through the transparent plate 31 is transmitted to the polarizing beam splitter 32.
Is separated into two polarization components. The light separated by the transparent plate 31 and the polarization beam splitter 32 is passed through matching lenses 33, 34, and 35 to optical fibers 36, 37, and 38, respectively.
And is guided to the spectroscopes 40, 41, 42.

Light output from the spectrometers 40, 41, and 42 is detected by photodetectors 50, 51, and 52, respectively.
The detection results of the photodetectors 50, 51, and 52 are output from the spectrometer 40 to
42 and a controller 6 for controlling the photodetectors 50 to 52
Input to 0. The control device 61 processes the measurement data input from the controller 60 and controls the measurement by the controller 60. Although FIG. 1 does not show a supporting device for the sample 70, the optical components, and the like, a general-purpose method such as a general optical bench is used for the supporting device.

Various light sources such as high-brightness monochromatic light such as laser light, white light, and monochromatic light obtained by dividing white light are used as the light source 10. The optical fibers 11 and 36 to 38 do not require a special function such as polarization preservation, and may be any fibers that are suitable for the target measurement wavelength. The smaller the fiber diameter, the better, but it is not particularly limited.

The collimator lens 20 produces a parallel light beam suitable for optical components used thereafter, and converts the diffused light emitted from an optical fiber or the like into a parallel light beam. Depending on the configuration of the measuring instrument, it is possible to directly emit diffused light or parallel light from the light source 10 without using the optical fiber 11 or the collimator lens 20.

The polarizer 21 may be a commonly used one such as a polarizing prism. The exit lens 22 focuses parallel light on the surface of the sample 70, and determines the focal length according to the device configuration. When the light beam incident on the exit lens 22 is small, the exit lens 22 need not be used. The incident lens 30 is a lens for making parallel when diffused light is reflected from the surface of the sample 70, and its focal length is determined according to the device configuration. In addition, the exit lens 22
When the parallel light is used without using the lens, the incident lens 30 may not be used.

The transparent plate 31 receives parallel light at a Brewster angle determined by its refractive index. The reflected light from the transparent plate 31 is incident on the optical fiber 36 by the matching lens 33. The light transmitted through the transparent plate 31 is polarized by a polarizing beam splitter 32 having a different azimuth from the azimuth of the transparent plate 31.
At a specified angle. Polarizing beam splitter 3
The two lights emitted from the two are respectively matched lenses 3
The light is incident on the optical fibers 37 and 38 by the optical fibers 4 and 35.

The light incident on the optical fibers 36, 37, and 38 is incident on spectroscopes 40, 41, and 42, respectively, where the light is split, and the photodetectors 50, 51, and 52 measure the respective polarization intensities. The measurement results of the photodetectors 50, 51, and 52 are input to the controller 60, and the controller 6
At 0, the polarization state of the reflected light from the sample 70 is measured based on each measurement result. The control device 6 inputs measurement data indicating the polarization state from the controller 60, and measures the film thickness and optical constant of the thin film on the surface of the sample 70. The spectrometer 4
The resolution of 0 to 42 is determined as needed. When the light used for the light source 10 is monochromatic light, the spectroscopes 40 to 42 are not necessary. The photodetectors 50 to 52 are of a photocurrent type according to the light intensity,
Use an appropriate one such as a photon counting type.

In the ellipsometry apparatus according to the present embodiment, the point of irradiating the sample with linearly polarized light is the same as that of the conventional rotary analyzer type. The point that is significantly different from the conventional one is that in the conventional rotary analyzer type, the analyzer is rotated and the polarization state of the reflected light is measured from the signal intensities in a number of polarization directions. The point is that the signal intensity in the polarization direction is measured by a method without rotating the analyzer.

In this embodiment, as means for that purpose,
First, when the reflected light from the sample 70 is made incident on the transparent plate 31 at a Brewster angle. As a result, the reflected light of the transparent plate 31 includes the known ratio of the S-polarized component determined by the azimuth of the transparent plate 31 in the reflected light from the sample 70, and the transmitted light has the S-polarized component reduced at a known ratio. Become light.

Next, the transmitted light of the transparent plate 31 is made incident on a polarizing beam splitter 32 whose azimuth is directed to a direction different from that of the transparent plate 31, so that two azimuths different from the reflected light of the transparent plate 31 are obtained. The intensity of the polarization component of the angle can be measured. As a result, the polarization component intensities in three directions can be measured, so that the polarization components of the light reflected from the surface of the sample 70 can be obtained. Further, since the optical system for measuring the polarization is configured using an optical element having no or negligible chromatic aberration, the ellipsometry apparatus can be applied to light of multiple wavelengths. In addition, since the light from these optical systems may be about the diameter of the measurement beam, the ellipsometry apparatus can be made small.

It should be noted that the present invention is not limited to only the above-described embodiment, and can be implemented with appropriate modifications without departing from the scope of the invention. (Summary of Embodiment) The configuration, operation and effect shown in the embodiment are summarized as follows.

The ellipsometry apparatus shown in the embodiment is an ellipsometry apparatus for measuring the state of the sample 70 by measuring the polarization state of the reflected light from the sample 70. A plurality of polarizing means (31, 32) for polarizing, and the plurality of polarizing means (3
1, 32), a plurality of detecting means (50, 51, 52) for detecting the reflected light polarized in a plurality of directions, and detecting the reflected light from the detection results of the plurality of detecting means (50, 51, 52). Measuring means (60) for measuring the polarization state of light
And is composed of

Therefore, according to the ellipsometry apparatus, the plurality of polarization means (31, 32), each of which is fixed and reflects the reflected light from the sample (70), detects the reflected light polarized in a plurality of directions. Then, since the polarization state of the reflected light is measured, the polarization state is measured for many wavelengths of the reflected light without providing a rotating part, and the sample (7) is measured.
It is possible to measure the thickness and optical constant of the thin film of 0), that is, the refractive index and the absorptance for the wavelength. Therefore, the measurement can be performed promptly without any limitation on the measurement time, there is no failure caused by the rotating part, and the measuring instrument can be configured in a small size because there is no need to configure the rotating part.

[0023]

According to the ellipsometry apparatus of the present invention,
Detecting the reflected light polarized in a plurality of directions by a plurality of polarizing means each of which is fixed and polarizes the reflected light from the sample,
Since the polarization state of the reflected light is measured, the polarization state is measured for a number of wavelengths of the reflected light without providing a rotating part, and the thickness or optical constant of the thin film of the sample, that is, the refractive index or absorption for the wavelength. The rate can be measured. Therefore, the measurement can be performed promptly without any limitation on the measurement time, there is no failure caused by the rotating part, and the measuring instrument can be configured in a small size because there is no need to configure the rotating part.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an ellipsometry device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the principle of a conventional ellipsometry device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Light source 11 ... Optical fiber 20 ... Collimator lens 21 ... Polarizer 22 ... Exit lens 30 ... Incident lens 31 ... Transparent plate 32 ... Polarized beam splitter 33-35 ... Matching lens 36-38 ... Optical fiber 40-42 ... Spectroscope 50 ~ 52 ... Photodetector 60 ... Controller 61 ... Control device 70 ... Sample

Claims (1)

[Claims] 1. An ellipsometer for measuring the state of a sample by measuring the polarization state of light reflected from the sample, comprising: a plurality of polarization means each fixed to polarize the reflected light; A plurality of detecting means for detecting the reflected light polarized in a plurality of directions by means, and a measuring means for measuring a polarization state of the reflected light from a detection result of the plurality of detecting means. Ellipsometry device.