KR102515267B1 - High-aspect-ratio sample inspection apparatus based on a near-normal-incidence ellipsometer - Google Patents

Abstract

The present invention projects quasi-normal incident light of 10° or less onto a sample and uses the reflected light to inspect the surface and thin film state of the sample. It relates to a technique capable of inspecting the surface and thin film state of a sample having a high aspect ratio through an ellipsoidal structure.
A high aspect ratio sample inspection device based on a quasi-normal incidence ellipsometer according to the present invention includes a light source that generates light, and is disposed below the light source to focus the light generated from the light source to a feed side to have a quasi-normal incidence angle of 10 ° or less. A focusing lens disposed below the focusing lens to polarize the incident light output from the focusing lens into a polarized state in one area and outputting only a specific polarization among the reflected light output from the phase retarder in the other area. A phase retarder disposed below the polarizer, varying the azimuth angle of the incident light applied to one side of the polarizer and projecting it toward the sample side, and varying the azimuth angle of the reflected light applied from the sample side and outputting it to the other side of the polarizer, and Calculate the elliptic constant for measuring the thin film state of the sample using the intensity of the reflected light output from the retarder, but calculate the amplitude ratio (ψ) and phase difference (Δ) from the intensity of the reflected light corresponding to the combination of the polarizer azimuth angle and the phase retarder azimuth angle. It is characterized in that it is configured to include an inspection unit for determining the surface and thin film state of the sample by calculating the elliptic constant.

Description

High-aspect-ratio sample inspection apparatus based on a near-normal-incidence ellipsometer

The present invention projects quasi-normal incident light of 10° or less onto a sample and uses the reflected light to inspect the surface and thin film state of the sample. It relates to a technique capable of inspecting the surface and thin film state of a sample having a high aspect ratio through an ellipsoidal structure.

Ellipsometry is widely used as a non-destructive measurement method in industrial fields using various thin films, and is particularly useful for non-destructively measuring the thickness of thin films in the semiconductor field.

The elliptic method is a method for determining factors such as density change, optical thickness, and complex refractive index, which are factors that change polarization, by injecting light having a specific polarization state into a sample and then measuring and analyzing the changed polarization state of the reflected light. is called an ellipsometer.

1 is a configuration diagram showing a conventional ellipsometer, which generally includes a light source 1, a polarizer module 2, an analyzer module 5, and a photodetector 6.

The conventional ellipsometer may further include focusing optical modules 3 and 4 for focusing incident light incident on the sample 10 or reflected light reflected from the sample 10, and each time a driving pulse is applied, a unit angle It may include a motor that rotates the polarizer module 2 by unit angle by rotating each.

According to this configuration, the light generated from the light source 1 is incident on the sample 10 in a polarization controlled state in the polarizer module 2, and the light reflected from the sample 10 is incident on the analyzer module 5, , the analyzer module 5 detects the polarization state, and the light passing through the analyzer module 5 is incident on the photodetector 6, and the intensity of the incident light is measured as an electrical signal such as voltage or current. .

Then, the photodetector 6 transmits the reflected light, that is, the intensity of the measurement light to a computer, and the computer analyzes the change in polarization state from the intensity information of the measurement light using an analysis program to determine an ellipse constant, and uses the determined ellipse constant. Thus, the state of the surface structure or thin film thickness of the sample 10 is determined.

At this time, the angle of incidence (θ) and the angle of reflection (θ′) of the light incident on the sample 10 are the same, and in general, the angle of incidence (θ) is set differently according to the height of the fine pattern formed on the surface of the sample 10 and the thickness of the thin film layer. , usually set within the range of around 60°.

On the other hand, in the semiconductor industry, as the degree of integration of devices increases, miniaturization and ultra-thinning of patterns are continuously performed, and the usefulness of the ellipsoid is also increasing in proportion to this. These ellipsometers were initially used limitedly for measuring the thickness of single-layer thin films using a single wavelength, but with the development of spectroscopic ellipsometers that measure at multiple wavelengths and the introduction of modeling analysis methods, high-precision quantitative analysis of the structure and optical constants of multi-layer thin film samples this has become easier

A spectroscopic ellipsometer (SE) basically has a polarizer-sample-analyzer (PSA) arrangement structure, and is divided into a RAE ellipsometer driven by a rotating analyzer method and an RPE ellipsometer driven by a rotating polarizer method. , Both of these RAE ellipsometers and RPE ellipsometers have disadvantages in that the sign of the phase angle (Δ) cannot be determined or the phase angle (Δ) measurement error increases in the dielectric region where sinΔ is near “0”.

In addition, general spectroscopic ellipsometers with incident angles of around 60° have lower sensitivity to structural defects as the width of the pattern relative to the wavelength decreases. It is unreasonable to detect structural defects in the lower layer of the sample, such as grooves.

Therefore, there may be a method of analyzing the state of a sample having a high aspect ratio by setting the angle of incidence of light projected onto the sample 10 to be smaller, but as shown in FIG. Since there is a limit to the spatial arrangement of optical elements having a certain size in the spectrometer structure, there is a disadvantage in that it is impossible to set an incident angle below a certain level.

1. Korean Patent Registration No. 1936792 (Name: Optical measuring instrument for measuring thin film structures based on interferometer and ellipsometer) 2. Korean Patent Publication No. 2017-0055661 (Name: Large-area real-time thin-film measurement spectroscopic image ellipsometry device)

Therefore, the present invention was created in view of the above circumstances, and projects quasi-normally incident light of 10° or less onto a sample using an ellipsometer having a structure in which incident light and reflected light share one polarizer and one phase retardant, and Its technical purpose is to provide a quasi-normal incidence ellipsometer-based high-aspect-ratio sample inspection device that can more reliably inspect the surface structure and thin film thickness of a high-aspect-ratio sample by acquiring the elliptic constant of the reflected light.

According to one aspect of the present invention for achieving the above object, a light source for irradiating incident light toward a sample, a focusing lens disposed below the light source and focusing the incident light to have a quasi-normal incidence angle of 10 ° or less, the focusing lens A polarizer disposed below the lens to polarize the incident light passing through the focusing lens and the reflected light reflected from the sample into linearly polarized light, disposed below the polarizer to polarize the incident light passing through the polarizer and the reflected light reflected from the sample Calculate the elliptic constant for measuring the thin film state of the sample using the phase retarder for varying the phase angle of and the intensity of the reflected light output from the polarizer, but the intensity of the reflected light corresponding to the combination of the polarizer azimuth angle and the phase retarder azimuth angle A high aspect ratio sample inspection device based on a quasi-normal incidence ellipsometer is provided, characterized in that it comprises an inspection unit for determining the surface and thin film state of the sample by calculating the elliptic constant of the amplitude ratio (ψ) and the phase difference (Δ) from .

In addition, the focusing lens focuses and outputs the reflected light output from the polarizer, and a mirror for changing the path of the reflected light to the inspection unit is additionally disposed on the upper side of the focusing lens. A high aspect ratio sample inspection device is provided.

In addition, an incident angle variator for varying the incident angle of light generated from the light source is disposed below the light source, and the incident angle variator is capable of moving an incident angle variable plate having a through hole of a predetermined size inside a case having an open top and bottom surface. A high aspect ratio sample inspection device based on a quasi-normal incidence ellipsoid is provided, characterized in that it is fastened and configured.

와 위상지연자의 16개 방위각(C)

로 이루어지는 방위각 조합(P,C) 조건에서의 반사광 세기로부터 타원상수를 산출하는 것을 특징으로 하는 준 수직입사 타원계 기반의 고종횡비 시료 검사 장치가 제공된다.In addition, the inspection unit has 8 azimuth angles (P) of the polarizer

and 16 azimuths of the phase retarder (C)

A quasi-normal incidence ellipsometer-based high aspect ratio sample inspection device is provided, characterized in that the elliptic constant is calculated from the reflected light intensity under the azimuth combination (P, C) condition consisting of.

,

를 포함한 제1 측정값을 산출하여 tanψ 값을 결정하고, tanψ가 결정된 상태에서 제2 방위각 조합 조건에서의 반사광 세기를 이용하여

또는

의 제2 측정값을 산출하여 cosΔ값을 결정함으로써, 타원상수 ψ와 Δ를 획득하는 것을 특징으로 하는 준 수직입사 타원계 기반의 고종횡비 시료 검사 장치가 제공된다.In addition, the inspection unit uses the reflected light intensity in the first azimuth combination condition

,

A first measurement value including

or

A high aspect ratio sample inspection device based on a quasi-normal incidence ellipsometer is provided, characterized in that ellipticity constants ψ and Δ are obtained by calculating the second measurement value of and determining the cosΔ value.

또는

의 제3 측정값을 산출하여

또는

를 결정함으로써, 상기 cosΔ의 "Δ" 부호를 획득하여 적용하는 것을 특징으로 하는 준 수직입사 타원계 기반의 고종횡비 시료 검사 장치가 제공된다. In addition, the inspection unit uses the reflected light intensity in the third azimuth combination condition

or

By calculating the third measured value of

or

A quasi-normal incidence ellipsometer-based high aspect ratio sample inspection apparatus is provided, characterized in that by determining, obtaining and applying the “Δ” sign of the cosΔ.

각각에 대한 위상자의 16개 방위각

각각에서 측정한 128개의 빛(반사광)의 세기들로부터 타원상수인 Δ(위상차)와 ψ(진폭차)를 용이하게 산출함으로써, 높은 종횡비를 가지는 미세 패턴 시료의 하부층 구조결함을 보다 신뢰성 있게 검사할 수 있다. According to the present invention, in a quasi-normal incidence ellipsoid structure in which incident light and reflected light share one polarizer and one phase retardant, eight azimuth angles of the polarizer

16 azimuth angles of the phasor for each

By easily calculating Δ (phase difference) and ψ (amplitude difference), which are elliptic constants, from the intensities of 128 light (reflected light) measured at each, it is possible to more reliably inspect structural defects in the lower layer of a micro-pattern sample having a high aspect ratio. can

In addition, the present invention can be extended and applied to a quasi-normal incidence spectroscopic ellipsometer using a non-ideal quarter-wavelength phase retarder. can overcome the limitations of existing SE-based OCD measurement equipment.

1 is a configuration diagram showing a conventional ellipsometer;
2 is a diagram showing a schematic configuration of a high aspect ratio sample inspection apparatus based on a quasi-normal incidence ellipsometer according to a first embodiment of the present invention.
FIG. 3 is a view for explaining the configuration of the incident angle variable device 700 shown in FIG. 2;
4 is a diagram showing azimuth combination groups of different polarizers 300 and phase retarders 400 for acquiring elliptic constants.

The embodiments described in the present invention and the configurations shown in the drawings are only preferred embodiments of the present invention, and do not represent all the technical ideas of the present invention, so the scope of the present invention is limited to the embodiments and drawings described in the text. should not be construed as being limited by That is, since the embodiment can be changed in various ways and can have various forms, it should be understood that the scope of the present invention includes equivalents capable of realizing the technical idea. In addition, since the object or effect presented in the present invention does not mean that a specific embodiment should include all of them or only such effects, the scope of the present invention should not be construed as being limited thereto.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs, unless defined otherwise. Terms defined in commonly used dictionaries should be interpreted as being consistent with meanings in the context of related art, and cannot be interpreted as having ideal or excessively formal meanings that are not clearly defined in the present invention.

1 is a diagram showing a schematic configuration of a high aspect ratio sample inspection device based on a quasi-normal incidence ellipsometer according to a first embodiment of the present invention.

Referring to FIG. 1, a quasi-normal incidence ellipsometer-based high aspect ratio sample inspection apparatus according to a first embodiment of the present invention includes a light source 100, a focusing lens 200, a polarizer 300, and a phase retarder 400. ), a mirror 500, and an inspection unit 600, and an incident angle variable device 700 is further provided between the light source 100 and the focusing lens 200.

Here, the light source 100, the focusing lens 200, the polarizer 300, and the phase retarder 400 are sequentially arranged to have an axis C perpendicular to the surface of the sample 10 on the upper side of the sample 10 to be inspected. It is arranged so that incident light and reflected light pass through one polarizer 300 and one phase retarder 400 based on the sample 10.

That is, the polarizer 300 and the phase retarder 400 are disposed on the upper side of the sample 10 to project the polarized light generated on one side of the sample 10 to the sample 10 side, and to the other side of the sample 10. It has an ellipsoidal structure that outputs light reflected from the surface of the sample 10 as measurement light. At this time, the incident light incident toward the sample 10 and the reflected light output from the sample 10 have an incident angle θ of 3 ° to 10 ° relative to the vertical axis C, which is equivalent to the vertical, that is, quasi-normal.

The light source 100 is a light generating device that irradiates incident light toward the sample 10, and generates light of various wavelength bands from deep ultra violet (DUV) to near infrared, that is, white light.

The focusing lens 200 is disposed below the light source 100 to focus the light output from the light source 100 toward the polarizer 300 and to focus the reflected light applied from the polarizer 300 toward the mirror 500. . At this time, the focusing lens 200 focuses the light generated from the light source 100 toward the specimen 10 to have a quasi-normal incident angle of 10° or less, and outputs the focused light.

The polarizer 300 is disposed below the focusing lens 200 and polarizes the incident light passing through the focusing lens 200 and the reflected light reflected from the sample 10 into linearly polarized light. That is, in one area of the polarizer 300, the light applied through the focusing lens 200 is polarized in a linearly polarized state and output to the phase retarder 400, and in the other area, the reflected light output from the phase retarder 400 is polarized. Among them, only specific polarized light is output to the focusing lens 200 . At this time, in the polarizer 300, a first area on one side of the vertical axis C is set as a polarization area for polarizing light applied from the light source 100, and a second area on the other side is set as a polarization area for polarizing light applied from the sample 10. It is set as an inspection area that passes only a specific polarized light among reflected light.

In addition, the light generated from the light source 100 generally appears as non-polarized light that cannot be expressed as a specific polarization state, and the polarizer 300 rotates by a certain angle (polarization angle) unit by a motor to pass through the polarizer 300. It changes the azimuth angle of linearly polarized light (incident light) and reflected light.

The phase retarder 400 is disposed below the polarizer 300, changes the azimuth angle of the incident light applied to one side of the polarizer 300, projects it toward the sample 10, and applies it from the sample 10 side. The azimuth angle of the reflected light is varied and output to the other area of the polarizer 300.

At this time, the polarization state of the light incident on the sample 10 is reflected and output in a deformed form according to optical and structural characteristics such as the complex refractive index and thickness of the sample 10 .

The mirror 500 is disposed above the focusing lens 200, changes the path of the reflected light output through the focusing lens 200, and outputs the reflected light to the inspection unit 600. It is arranged to have a certain inclination angle so as to output in a direction parallel to the sample 10 .

The inspection unit 600 collects reflected light input through the mirror 500 as measurement light, analyzes the measurement light, and calculates an ellipse constant corresponding to an amplitude ratio (ψ) and a phase difference (Δ) of polarization, and calculates the ellipse constant By applying a predetermined mathematical algorithm to determine a value satisfying the ellipticity constant as the surface height or depth value of the sample 100 or the thickness value of the thin film, the surface structure and thin film state of the sample 10 are inspected. At this time, a mathematical algorithm for calculating the state value of the specimen 100 using an elliptic constant may be set as a known mathematical function, and a detailed description thereof will be omitted.

The incident angle variable unit 700 is for varying the incident angle of the light source 10 projected toward the specimen 10, and the incident light path toward the specimen 10 has an incident angle θ in the range of 10° or less toward the specimen 10. set

As shown in FIG. 3, such an angle of incidence variable device 700 penetrates a case 710 having open surfaces 711 and 712 formed on the top and bottom surfaces and one side of the case 710 while being disposed at a predetermined position. It is configured to include a variable incidence angle plate 720 on which a ball 721 is formed, and the variable incidence angle plate 720 is movably fastened inside the case 710, and the through hole 721 is movable according to the position of the variable incidence angle plate 720. ) to change the incident angle of the light output to the sample 10 side.

That is, as shown in FIGS. 3 (A) and (C), the incidence is incident on the sample 10 corresponding to the distances d1 and d2 between the through hole 721 of the variable incidence angle plate 720 and the optical axis C. The angle of incidence of the light So is set differently, and the movement range of the through hole 721 is set to a range in which the angle of incidence of the sample 10 is 3 to 10°.

That is, the present invention has difficulty in arranging the light detection means including the light source 100 in a general elliptical structure as shown in FIG. By configuring the incident light and the reflected light to be shared, a quasi-normal incidence ellipsoid that overcomes the spatial arrangement restrictions of optical elements is realized.

Next, a process of calculating the elliptic constant ψ and Δ using the measurement light in the inspection unit 600 will be described. Here, ψ is an angle corresponding to the polarization amplitude ratio, and Δ is an angle corresponding to the polarization phase difference.

First, in the present invention, as shown in FIG. 2, the light emitted from the light source 100 is projected toward the surface of the sample 10 at a very small incident angle within 10 ° through the incident angle variator 700, and the incident light is After sequentially passing through the polarizer 300 and the phase retarder 400, it is reflected on the surface of the sample 10, and the reflected light reflected from the surface of the sample 10 passes through the phase retarder 400 and the polarizer 300 sequentially. After passing through, the light path is changed through the mirror 500 and applied to the inspection unit 600.

타원계 구조를 갖는 것으로, 검광자를 통과한 빛의 존스 벡터는 하기 수학식1로 표현된다. 이때, 본 발명에서는 하나의 편광자(300)를 입사광과 반사광이 공유하는 구조인 바, 이하에서는 입사광이 통과하는 위치의 편광자(300) 영역은 편광자로, 반사광이 통과하는 위치의 편광자(300) 영역은 검광자로 구분하여 설명한다. That is, the present invention has a polarizer-corrector (phase retarder)-sample-corrector (phase retarder)-analyzer arrangement

It has an elliptical structure, and the Jones vector of light passing through the analyzer is expressed by Equation 1 below. At this time, in the present invention, a structure in which incident light and reflected light share one polarizer 300, hereinafter, the area of the polarizer 300 where the incident light passes is a polarizer, and the area of the polarizer 300 where the reflected light passes is explained separately as an analyzer.

와

는 각각 투과축-소거축 좌표상에서 검광자를 통과한 빛의 존스 벡터와 검광자의 존스 행렬,

는 회전각도가

인 회전 존스 행렬,

는 빠른축-느린축 좌표상에서 위상지연자의 존스 행렬,

는 x-y 직교좌표축 상에서 등방성 시료의 반사를 나타내는 존스 행렬이고,

는 투과축-소거축 좌표상에서 편광자를 통과한 빛의 존스벡터이다.Here, the expression of the Jones vector and the Jones matrix follow Azzam's expression,

and

are the Jones vector of the light passing through the analyzer and the Jones matrix of the analyzer, respectively, on the transmission axis-elimination axis coordinates,

is the rotation angle

is the rotated Jones matrix,

Is the Jones matrix of the phase retarder on the fast axis-slow axis coordinates,

Is a Jones matrix representing the reflection of an isotropic sample on the xy Cartesian coordinate axis,

Is the Jones vector of light passing through the polarizer on the transmission axis-elimination axis coordinates.

와 검광자의 방위각

는

의 관계를 가지며, 입사광에 대한 위상지연자의 방위각(C₁)과 반사광에 대한 위상지연자의 방위각(C₂)은

와 같은 관계를 갖는다.In the present invention, since incident light and reflected light share the polarizer 300 and the phase retarder 400, the azimuth angle of the polarizer

and the azimuth of the analyzer

Is

, and the azimuth angle of the phase retarder for incident light (C ₁ ) and the azimuth angle of the phase retarder for reflected light (C ₂ ) are

have the same relationship as

,

를 상기 수학식 1에 대입하면 검광자를 통과한 빛의 존스 벡터는 하기 수학식 2와 같다.Therefore,

,

When Equation 1 is substituted into Equation 1, the Jones vector of the light passing through the analyzer is equal to Equation 2 below.

In addition, by solving Equation 2 to obtain the basic equations for obtaining the elliptic constant from the measured light intensity information, an expression of the electric field as in Equation 3 can be obtained.

The inspection unit 600 obtains the ellipticity constants Δ, ψ from the intensity of light corresponding to a combination of three or more independent azimuth angles (P, C) through a numerical analysis method. Here, P is the azimuth angle of the polarizer 300, and C is the azimuth angle of the phase retarder 400.

(또는

) 이거나

(또는

) 인 경우 전기장의 표현은 다음과 같다.first,

(or

) or

(or

), the expression of the electric field is

로서

하여도 달라지지 않으며,

또는

를 중심으로 좌우 대칭인 특성을 갖는다.At this time, the electric field in Equation 4 has a period

as

does not change,

or

It has a left-right symmetrical characteristic centered on .

의 값에 대한 전기장의 표현은 표1과 같다.And, some special

The expression of the electric field for the value of is shown in Table 1.

이고,

,

,

이다.here,

ego,

,

,

am.

(또는

) 이거나

(또는

) 인 경우 전기장의 표현은 수학식 5와 같다.also,

(or

) or

(or

), the expression of the electric field is as shown in Equation 5.

이고,

이다.here,

ego,

am.

의 주기를 갖기 때문에

로 하여도 바뀌지 않지만,

또는

주위의 대칭성은 없다. 몇가지

에 대한 전기장 표현은 하기 표2와 같다.Equation 5 is the same as Equation 4 above.

because it has a cycle of

does not change even if

or

There is no symmetry around. a few

The electric field expression for is shown in Table 2 below.

The results of Table 1 and Table 2 above are summarized in Table 3.

,

이다. Table 3 is an expression of the electric field according to different combinations of azimuth angles (C, P),

,

am.

That is, an expression of light intensity can be obtained from the expression of the electric field in Table 3, and ellipticity constants Δ and ψ can be calculated from light intensities for each combination of azimuth angles (P, C).

일 때의 빛의 세기를

로 정의하고,

이고

또는

일 때의 빛의 세기를 각각

,

,

,

와 같이 정의하여, 일련의 유도과정을 거치게 되면 수학식6과 같은 타원상수 표현들을 획득할 수 있다.for example,

the intensity of light at a time

defined as,

ego

or

The intensity of light at the time of day

,

,

,

By defining as, when a series of derivation processes are performed, elliptic constant expressions such as Equation 6 can be obtained.

이다.here,

am.

, 세로축은 위상자의 방위각

를 나타내며 단위는 모두

이다. 빛의 세기 측정 기준값은 속이 찬 원으로 표시된

의 방위각 조합에서 측정한 값이다. On the other hand, if the azimuth (P, C) combination is not independent, the obtained constants are different depending on the combination, and FIG. 4 (A) shows them classified by group. In FIG. 4 (A), the horizontal axis is the azimuth angle of the polarizer.

, the vertical axis is the azimuth of the phasor

, and units are all

am. The reference value for measuring the light intensity is indicated by a solid circle.

It is a value measured from the azimuth combination of

의 조합이

,

,

,

인 곳에서 측정(또는 이들을 평균)한 값을

의 조합이

,

,

,

인 곳에서 측정(또는 이들을 평균)한 값으로 나눈 값은

의 측정값이 되며,

의 조합이

,

,

,

인 곳에서 측정(또는 이들을 평균)한 값을

의 조합이

,

,

,

인 곳에서 측정(또는 이들의 평균)한 값으로 나눈 값은

의 측정값이 된다. 또한,

의 조합이

,

,

,

인 곳에서 측정(또는 이들을 평균)한 값을

의 조합이

,

,

,

인 곳에서 측정(또는 이들을 평균)한 값으로 나눈 값은

의 측정값이 된다.in other words,

the combination of

,

,

,

The value measured (or averaged) at

the combination of

,

,

,

The value divided by the value measured (or the average of them) at

is the measured value of

the combination of

,

,

,

The value measured (or averaged) at

the combination of

,

,

,

The value divided by the value measured (or the average of them) at

is the measured value of also,

the combination of

,

,

,

The value measured (or averaged) at

the combination of

,

,

,

The value divided by the value measured (or the average of them) at

is the measured value of

,

등의 측정값을 구할 수 있으며, 이로부터

가 결정될 수 있다.In this way, with the reference value for measuring the light intensity as the denominator and the intensity of the measured value as the numerator,

,

etc. can be obtained, from which

can be determined.

가 결정된 상태에서

의 측정값을 산출하는 방법은 다음과 같다.

is determined

The method for calculating the measured value of is as follows.

의 조합이

,

,

,

,

,

,

,

인 곳에서 측정(또는 이들을 평균)한 값을

의 조합이

,

,

,

인 곳에서 측정(또는 이들을 평균)한 값으로 나눈 값이

이 되며,

의 조합이

,

,

,

,

,

,

,

인 곳에서 측정(또는 이들을 평균)한 값을

의 조합이

,

,

,

인 곳에서 측정(또는 이들을 평균)한 값으로 나눈 값이

의 측정값이 된다.in other words,

the combination of

,

,

,

,

,

,

,

The value measured (or averaged) at

the combination of

,

,

,

The value divided by the value measured (or the average of them) at

becomes,

the combination of

,

,

,

,

,

,

,

The value measured (or averaged) at

the combination of

,

,

,

The value divided by the value measured (or the average of them) at

is the measured value of

또는

의 측정값을 결정할 수 있는

의 조합을 보여준다. 여기에서 속이 찬 원은

를 구하는

의 조합을 나타내며 속이 빈 원은

를 구하는

의 조합을 나타낸다. Figure 4 (B) is

or

can determine the measured value of

shows the combination of The hollow circle here

to get

Represents a combination of and the hollow circle is

to get

represents a combination of

가 결정된 상태에서 도4 (B)의 방위각 조합을 이용하여

를 결정할 수 있다.like this

In the state where is determined, using the azimuth combination of FIG. 4 (B)

can decide

측정 방식은 Δ의 부호를 결정하지 못하여

근방인 영역에서는

의 측정오차가 커지는 단점이 있다.However, the above

The measurement method cannot determine the sign of Δ,

In the neighboring area

There is a disadvantage that the measurement error of is large.

또는

의 측정값과

측정값을 이용하여 Δ의 부호를 결정함으로써, 정확한 Δ를 결정할 수 있다. Therefore, in the present invention

or

and the measurement of

By determining the sign of Δ using the measured values, the exact Δ can be determined.

또는

를 결정하기 위한

와

를 구하는

의 조합을 나타낸다. 여기서, 속이 찬 원은

를 구하는

의 조합을, 속이 빈 원은

를 구하는

의 조합을 나타낸다.Figure 4 (C) is

or

to determine

and

to get

represents a combination of Here, the hollow circle is

to get

, the hollow circle is

to get

represents a combination of

와 위상지연자의 16개 방위각(C)

로 이루어지는 방위각 조합(P,C) 조건에서의 빛의 세기 기준값과 빛의 세기 측정값을 이용하여 tanψ 값을 결정하기 위한

,

를 포함한 제1 측정값과, cosΔ값을 결정하기 위한

또는

의 제2 측정값 및, cosΔ에서 "Δ"의 부호를 결정하기 위한

또는

의 제3 측정값을 산출하고, 이를 통해 타원상수 ψ 와 Δ를 획득한다.That is, the inspection unit 600 determines the 8 azimuth angles (P) of the polarizer.

and 16 azimuths of the phase retarder (C)

For determining the tanψ value using the light intensity reference value and the light intensity measurement value in the azimuth combination (P, C) condition consisting of

,

For determining the first measured value and the cosΔ value including

or

For determining the second measured value of and the sign of “Δ” in cosΔ

or

Calculate the third measured value of , and obtain ellipticity constants ψ and Δ through this.

On the other hand, in the present invention, if the light source or the light quantity measuring device shows polarization dependence, it is preferable to determine the ellipticity constant from the measured light intensities by fixing the azimuth angle of the polarizer and varying only the azimuth angle of the compensator (phase retarder). When a change in polarization state due to a lens or mirror is concerned, it is more preferable to determine the ellipticity constant by fixing the azimuth angle of the polarizer.

의 조합을 자유롭게 사용할 수 있지만 측정하는 타원상수의 정확도가 이 소자들에 의한 편광의존성 보정 정도에 크게 의존하므로 신중한 접근이 요구되는데 이 소자들에 의한 편광의존성은 편광자를 회전시키면서 등방성 표준시료에 대해 측정한 빛의 세기를 이론적으로 도출한 빛의 세기와 비교하여 수치해석적으로 분석하면 한꺼번에 통합, 보정할 수 있다.At this time, if the polarization dependence of the light source or light quantity measuring device is corrected, including the influence of the lens or mirror, etc.

Combinations of can be used freely, but since the accuracy of the ellipticity constant to be measured is highly dependent on the degree of polarization dependence correction by these elements, a careful approach is required. The polarization dependence by these elements is measured for an isotropic standard sample while rotating the polarizer. Comparing the light intensity with the theoretically derived light intensity and analyzing it numerically, it can be integrated and corrected at once.

이고,

인 위상지연자를 보정기로 사용할 때에도 타원상수들을 정확하게 결정할 수 있게 하므로 파장의존성 위상지연자를 사용하더라도 DUV에서 NIR에 이르는 넓은 파장대역에 걸쳐 분광타원계를 정상적으로 작동할 수 있다. In addition, since the present invention does not have restrictions on the wavelength of light used, it can be easily applied to a near normal incidence spectroscopic ellipsometer. In particular, this quasi-normal incidence elliptic method has a non-ideal quarter-wavelength phase retarder, that is,

ego,

Since the ellipsoidal constants can be accurately determined even when using the phosphorus phase retarder as a compensator, the spectroscopic ellipsometer can operate normally over a wide wavelength band from DUV to NIR even when using the wavelength dependent phase retarder.

100: light source, 200: focusing lens,
300: polarizer, 400: phase retarder,
500: mirror, 600: inspection unit,
700: angle of incidence variable,
10: sample.

Claims (6)

A light source for irradiating incident light toward the sample;
A focusing lens disposed below the light source to focus the incident light to have a quasi-normal incidence angle of 10° or less;
A polarizer disposed below the focusing lens to polarize the incident light passing through the focusing lens and the reflected light reflected from the sample into linearly polarized light;
A phase retarder arranged below the polarizer to change the phase angle of the incident light passing through the polarizer and the reflected light reflected from the sample;
Calculate the ellipticity constant for measuring the thin film state of the sample using the intensity of the reflected light output from the polarizer, but calculate the amplitude ratio (ψ) and phase difference (Δ) from the intensity of the reflected light corresponding to the combination of the polarizer azimuth angle and the phase retarder azimuth angle A high aspect ratio sample inspection device based on a quasi-normal incidence ellipsometer, characterized in that it comprises an inspection unit for determining the surface and thin film state of the sample by calculating the elliptic constant.
According to claim 1,
The focusing lens focuses and outputs the reflected light output from the polarizer,
Quasi-normal incidence ellipsometer-based high aspect ratio sample inspection apparatus, characterized in that a mirror for changing the path of the reflected light to the inspection unit is additionally disposed on the upper side of the focusing lens.
According to claim 1,
An incident angle variator for varying an incident angle of light generated from the light source is disposed below the light source,
The angle of incidence variable is a high aspect ratio sample inspection device based on a quasi-normal incidence ellipsometer, characterized in that the angle of incidence variable plate having a through hole of a predetermined size is movably fastened inside a case having a structure in which the upper and lower surfaces are open.
According to claim 1,
The inspection unit has 8 azimuth angles (P) of the polarizer

and 16 azimuths of the phase retarder (C)

Quasi-normal incidence ellipsometer-based high aspect ratio sample inspection device, characterized in that for calculating the elliptic constant from the reflected light intensity under the azimuth combination (P, C) condition consisting of.
According to claim 4,
The inspection unit uses the reflected light intensity in the first azimuth combination condition

,

Determine the tan ψ value by calculating the first measured value including
With tanψ determined, using the reflected light intensity under the second azimuth combination condition

or

A high aspect ratio sample inspection device based on a quasi-normal incidence ellipsometer, characterized in that by calculating the second measurement value of and determining the cosΔ value, elliptic constants ψ and Δ are obtained.
According to claim 5,
The inspection unit uses the reflected light intensity in the third azimuth combination condition

or

By calculating the third measured value of

or

A high aspect ratio sample inspection device based on a quasi-normal incidence ellipsometer, characterized in that by determining, obtaining and applying the "Δ" sign of the cosΔ.

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