KR20170019954A - Confocal surface profiler and measuring method using the same - Google Patents

Abstract

The present invention relates to an apparatus and method for measuring a confocal surface, wherein the apparatus comprises: a light source generating light and irradiating the light onto a sample desired to be measure; an output-side beam splitter receiving the light reflected from the sample and separating a route of the light going into two; a first detector receiving a first light signal, separated, from the beam splitter, checking a focal surface, and thereby measuring a height value of a sampling point; and a second detector receiving a second light signal, separated, from the beam splitter and measuring gradient information on the sampling point from the second light signal at a point of time when the first light signal turns to the maximum. Accordingly, the present invention may overcome a physical limit that a surface profiler using an existing focal microscope is only able to measure a height value of a corresponding measurement location of a sample, solve problems of inconvenience in repeating an identical measurement process in a plurality of measurement locations for measuring an overall area of the sample, and solve a problem of taking a long time consumed in the measurement.

Description

[0001] The present invention relates to a confocal surface measuring apparatus and method,

The present invention relates to a technique for measuring a surface of a sample, and more particularly, to a technique for measuring a surface of a sample by using a confocal microscope to measure various information from a sampling point of the sample to be measured, To a focal surface measuring apparatus and method.

It is necessary to irradiate light in a three-dimensional confocal position in the fields of nano science, semiconductor, nano physics, nano chemistry, nanomaterials, nano optics, surface science, medical imaging, biology, biophysics, Researches on a technique for detecting a reflection signal and measuring a large-sized three-dimensional structure and a surface shape at a high speed with a high resolution in the optical axis direction and a plane direction are continuously being continued.

As a device for measuring the surface shape of a specific inspection sample at a high speed, there are a photometric method shape measuring device, a slit optical scanning method shape measuring device, a projection type moire measuring device, a white light interference measuring device, a single confocal shape measuring device, It has been developed and distributed in various ways.

However, the above-described various shape measuring devices substantially reveal their respective inherent problems. Specifically, the photometric method for measuring the surface shape using a reflected light source is only one point at a time. Therefore, in order to measure all the three-dimensional shapes, a mechanical XY scanning stage However, at this time, the measurement speed is limited due to the acceleration and deceleration limits of the driving stage, and thus, the measurement speed is slow.

In the prior art documents presented below, a method of restoring the surface profile of a sample using information obtained from the measurement position of the sample has been proposed.

Generalized Sampling Expansion, Athanasios Papoulis, IEEE, TRANSACTIONS ON CIRCUITS AND SYSTEMS, VOL, CAS-24, NO.11 NOVEMBER 1977.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the physical limit that a surface profiler using a conventional confocal microscope can measure only a height value of a corresponding measurement position of a sample and measure the entire area of the sample In order to solve the inconvenience that the same measurement process must be repeated at a plurality of measurement positions in order to increase the time required for the measurement.

According to an aspect of the present invention, there is provided a surface measuring apparatus comprising: a light source for generating light to irradiate a sample to be measured; An output side beam splitter for receiving the reflected light from the sample and separating the path of light into two; A first detector for measuring a height value for a sampling point of the sample by receiving a first light signal separated from the beam splitter and confirming confocal; And a second detector for receiving a second light signal separated from the beam splitter and measuring tilt information for a measurement position of the sample from the second light signal at a time when the intensity of the first light signal becomes maximum. .

The surface measuring apparatus according to an embodiment may include: an operation unit for restoring a surface profile related to the sample based on the height value measured through the first detector and the tilt information measured through the second detector; As shown in FIG.

In the surface measuring apparatus according to an embodiment, the tilt information may include at least one of a surface tilt value with respect to the measurement position, or a curvature indicating a degree of change of the tilt.

The surface measuring apparatus according to an embodiment may further include an input side beam splitter disposed between the light source and the sample and separating an incident path and a reflection path of light incident on the sample and then reflected.

A surface measuring apparatus according to an embodiment of the present invention includes: a diverging lens positioned in front of the light source to convert light radiated from the light source into parallel light and irradiate the sample with the parallel light; An objective lens positioned in front of the sample to converge incident parallel light to a focal point on the sample; And a converging lens for converging a parallel first light signal incident on the front of the first detector to a focal point on the first detector through a pin hole.

A surface measuring apparatus according to an embodiment may include at least one of a 3-D stage to which the sample is attached and moves the sample, or a mirror scanner to move the focus on the sample in a plane direction The sample may be scanned. The mirror scanner may be a PZT mirror scanner, a galvanometer mirror, or a polygon mirror scanner.

The surface measuring apparatus according to an embodiment may further include a light eliminating means disposed between the output side beam splitter and the second detector, wherein the light eliminating means includes a second light signal separating means for separating the parallel light beam from the output side beam splitter A first lens that focuses the light beam at a focal point; A pin hole positioned at the focal point and removing light appearing at points other than the focal point; And a second lens that converts the radial second light signal having passed through the focal point to parallel light and irradiates the second light to the second detector.

The surface measuring apparatus according to an embodiment may include a wave plate that is located in front of the light source and converts the light irradiated to the sample into a circularly polarized state to reduce the degree of dependency of the light reflectance on the surface to the polarization state plate. < / RTI >

According to another aspect of the present invention, there is provided a surface measuring apparatus including: a plurality of light sources for generating light having different wavelengths to irradiate a sample to be measured; Beam separating means for receiving the reflected light from the sample and separating the path of light into two; A first detector for measuring a height value for a sampling point of the sample by receiving a first light signal separated from the beam splitting means and confirming confocal; And a second detector for receiving a second light signal separated from the beam splitting means and measuring tilt information for a measurement position of the sample from the second light signal at a time when the intensity of the first light signal becomes maximum, .

According to another aspect of the present invention, there is provided a surface measuring apparatus, wherein when the light source irradiates a plurality of light signals having different wavelengths through different incident paths, the surface measuring apparatus is positioned between the light source and the sample, Further comprising an input side dichroic filter for controlling the incident light to be incident on the sample through one incident path by selectively passing or reflecting the light reflected from the sample, And can be implemented as an output-side dichroic filter that separates the progress path of light by wavelength.

In the surface measuring apparatus according to another embodiment, the first detector and the second detector can improve the efficiency of curvature measurement by measuring incident light signals using different focal spot sizes.

In the surface measuring apparatus according to another embodiment, the tilt information may include at least one of a surface tilt value with respect to the measurement position or a curvature indicating a degree to which the tilt varies.

According to another aspect of the present invention, there is provided a surface measuring apparatus comprising: a plurality of light sources for generating light having different polarization states to irradiate a sample to be measured; Beam separating means for receiving the reflected light from the sample and separating the path of light into two; A first detector for measuring a height value for a sampling point of the sample by receiving a first light signal separated from the beam splitting means and confirming confocal; And a second detector for receiving a second light signal separated from the beam splitting means and measuring tilt information for a measurement position of the sample from the second light signal at a time when the intensity of the first light signal becomes maximum, .

According to another aspect of the present invention, there is provided a surface measuring apparatus, wherein when the light source irradiates a plurality of light signals having different polarization states through different incident paths, the surface measuring apparatus is positioned between the light source and the sample, Further comprising a polarization beam splitter for controlling the polarization beam splitter to be incident on the sample through one incident path by selectively passing or reflecting the light beam according to the polarization state, Side polarized beam splitter for separating the progress path of the light according to the polarization state.

In the surface measuring apparatus according to another embodiment, the first detector and the second detector can improve the efficiency of curvature measurement by measuring incident light signals using different focal spot sizes.

In the surface measuring apparatus according to another embodiment, the tilt information may include at least one of a surface tilt value with respect to the measurement position or a curvature indicating a degree of change of the tilt.

According to an aspect of the present invention, there is provided a surface measuring method comprising: irradiating a sample to be measured with light generated from a light source; Separating the traveling path of light reflected from the sample into two by using an output side beam splitter; Measuring a height value of the sample with respect to a sampling point by receiving a first light signal separated from the beam splitter and confirming the confocal point, wherein when the intensity of the first light signal becomes maximum, Simultaneously measuring tilt information for a measurement position of the sample from the second light signal separated from the splitter; And restoring a surface profile related to the sample based on the measured height value and the slope information.

In the surface measuring method according to one embodiment, the tilt information may include at least one of a surface tilt value with respect to the measurement position or a curvature indicating a degree of change of the tilt.

In the method of measuring a surface according to an embodiment, simultaneously measuring the tilt information may include measuring a surface tilt and a tilt from a light pattern of the second light signal varying according to an angle of a surface on which light is focused at a measurement position of the sample, The higher order partial differential term information of the surface can be calculated.

Embodiments of the present invention utilize additional beamsplitters and detectors in a confocal microscope system to simultaneously measure tilt values and secondary partial differentials as well as height values of sample surfaces, The profile can be quickly restored and the number of measurement positions required for the sample profile can be significantly reduced.

1 is a diagram illustrating a confocal surface profiler according to one embodiment of the present invention.
FIGS. 2 to 5 are diagrams for explaining a method of deriving a theory used for simultaneously measuring the height and slope of a sample surface in embodiments of the present invention, and a method thereof.
6 is a view showing a confocal surface profiler using light sources of different wavelengths according to another embodiment of the present invention.
7 is a view showing a confocal surface profiler using a polarized light source according to another embodiment of the present invention.
8 is a view for explaining a method of removing a blurred light using an additional pin hole in a confocal surface profiler according to embodiments of the present invention.
9 is a diagram for illustrating a method and a sample scanning method for reducing polarization state dependence of light reflectance in a confocal surface profiler according to embodiments of the present invention.
10 is a flowchart illustrating a method of measuring a surface of a sample using a confocal surface profiler according to an embodiment of the present invention.

Prior to describing the embodiments of the present invention, after briefly introducing the problem of the surface profile using the conventional confocal microscopy principle, the technical means adopted by the embodiments of the present invention to solve the above-mentioned problems are sequentially .

A conventional surface profiler using a confocal microscope has the disadvantage that only the height value of the corresponding sampling point can be measured through the detector at the moment of confirming the confocal formed from the sample. Therefore, in order to restore the surface profile for the entire region of the sample, it is inconvenient to select a plurality of measurement positions on the sample, and to repeat the same measurement process therefrom. Particularly, this problem is further exacerbated as the area / size of the sample to be measured is larger.

Therefore, in the embodiments of the present invention described below, the slope value and the curvature as well as the height value are simultaneously measured at a measurement position of the sample to be measured, We propose a surface profiler that can reduce the number effectively. The surface measuring apparatus according to the embodiments of the present invention can measure the height and inclination or the secondary partial differential value of the reflecting surface simultaneously using the confocal microscope system, It can bring about a remarkable speed improvement compared to the profiler.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals used in the drawings should be construed to mean the same configurations, and these drawings are merely illustrative and do not limit the configuration of the invention.

1 is a view showing a confocal surface profiler according to an embodiment of the present invention in which a detector for confocal confirmation and a detector array for confirming the change in the position of light are used, This paper proposes a technical means to simultaneously measure the slope and the secondary partial differential value.

The light source 10 generates light and irradiates the sample 30 to be measured. In this embodiment, a single light source is exemplified. However, the light source may be composed of two or more light sources, Other embodiments will be described later with reference to FIGS. 6 and 7. FIG.

The sample 30 is a target object to be measured by the surface measuring apparatus of the present embodiment, and various positions of the sample surface are selected and the measurement is repeated. For this purpose, a mechanical and optical means for changing the measurement position can be utilized. In FIG. 1, a 3-D stage is shown to guide the incident light incident from the light source to be focused by moving the sample attached.

The input side beam splitter 20 is positioned between the light source 10 and the sample 30 and separates an incident path and a reflection path of light that is incident on the sample 30 and then reflected .

The output side beam splitter 40 receives the light reflected from the sample 30 and divides the path of light into two. Conventionally, the reflected light reflected from the sample 30 is incident on a single detector (corresponding to the first detector in Fig. 1), and only the height value of the sample can be measured. On the other hand, in the surface measuring apparatus according to the present embodiment Using this output side beam splitter 40, a part of the light incident on the first detector is guided to be incident on the second detector.

The first detector 50 receives the first light signal separated from the output side beam splitter 40 and confirms the confocal point so that the height value for the sampling point of the sample 30 . At this time, when the light emitted from the light source 10 is accurately focused on the surface of the sample 30 through the lens L2, the intensity of the light measured by the first detector becomes maximum, The height value for the position is determined.

A second detector array (60) receives a second light signal separated from the output side beam splitter (40), and at a time when the intensity of the first light signal reaches a maximum, The slope information for the measurement position of the sample 30 is measured. The inclination information preferably includes at least one of a surface inclination value with respect to the measurement position or a curvature indicating a degree of change of the inclination.

In a setup according to embodiments of the present invention, the slope information of the sample from the second detector 60 may be adjusted by changing the shape of the light incident on the sample 30, It can be obtained in different ways depending on the convenience of the user. Since the pattern of the light incident on the second detector 60 is changed according to the surface of the sample 30, the tilt information can be obtained from the surface of the sample 30. From the tilt information obtained from a certain point, D generalized sampling theorem '.

꼴로 놓도록 설정하였다. 도 2의 각 점은 측정 위치(sampling point)를 나타낸 것으로, x-y 평면 상에서의 서로 간의 간격은 x축의 경우

, y축의 경우

로 설정되며, 렌즈 표면은 f(x,y)의 함수로 정의되었다. 도 2에서 측정 위치

에서 높이 값

을 얻어낼 수 있다. 이때 빛이 집속된 표면의 각도에 따라 제 2 검출기(도 1의 부재번호 60)에 맺히는 빛의 패턴이 달라진다. 제 2 검출기에 맺히는 빛의 패턴으로부터 샘플 표면의 기울기, 표면의 고차항과 같은 정보를 동시에 얻을 수 있다. 샘플 표면의 높이와 기울기를 동시에 측정하기 위해 활용되는 보다 구체적인 이론의 도출 과정과 그 방법은 이후 도 3 내지 도 5를 참조하여 설명하도록 한다.Referring to FIG. 2, in which a sample lens is illustrated, FIG. 2 introduces a rationale for simultaneously measuring a height value and a slope information from each measurement position after positioning the lens on a three-dimensional coordinate axis. In FIG. 2, the coordinate axes and variables are set to apply the generalized sampling theorem. The axis of the objective lens (L2 lens) in FIG. 1 is set as the z axis and the vertical plane is set as the xy plane.

Respectively. Each point in FIG. 2 represents a sampling point, and the interval between them on the xy plane is the x-axis

, the case of the y axis

, And the lens surface is defined as a function of f (x, y). 2,

The height value

Can be obtained. At this time, depending on the angle of the surface on which the light is focused, the pattern of the light diffracted on the second detector (No. 60 in FIG. 1) changes. Information such as the slope of the sample surface and the high-order term of the surface can be simultaneously obtained from the pattern of light that is formed on the second detector. A more specific theory and a method for deriving the theory used for simultaneously measuring the height and the slope of the sample surface will be described with reference to FIGS. 3 to 5. FIG.

Return to Figure 1 again. 1 includes a diverging lens L1 positioned in front of the light source 10 to convert the light radiated from the light source 10 into parallel light and irradiating the light to the sample 30, An objective lens L2 for converging parallel light incident on the sample to a focal point on the sample and a parallel first light signal incident on the front of the first detector 50 and passing through the pin hole, 1 detector 50, as shown in FIG.

On the other hand, the surface measuring apparatus of Fig. 1 is configured to measure the surface profile (profile) about the sample based on the height value measured through the first detector 50 and the tilt information measured through the second detector 60 (Not shown) for restoring the original image data.

Hereinafter, when the incident light is in the form of a gaussian beam and the confocal state is confirmed in the first detector with respect to one measurement position, a description will be given of how to reflect the reflected light through the surface at the measurement position do. In the calculation process according to the following mathematical modeling, it is assumed that the third order differential coefficient near the measurement position is negligibly small. When the light is incident on the surface, the reflectance of the object varies depending on the direction of polarization and incidence direction of the light. When the circularly polarized light is incident within an angle of 25 degrees, the difference in reflectance is negligibly small For the sake of convenience, calculations were performed assuming such light.

Fig. 3 shows the pattern change of light when the surface is inclined at the measurement position. In FIG. 2, the modeling is performed using the cartesian coordinate system for the generalized sampling theorem. However, when describing the reflection of light on the surface, the spherical coordinate system (θ, φ) is utilized . The z-axis is set to the θ = 0 axis and the degree of inclination of the surface of the measurement position is expressed based on this.

Referring to FIG. 3, when a circularly polarized Gaussian beam enters the sample within 25 degrees, the profile of the beam reflected from the surface also becomes a Gaussian beam. However, the beam profile after the reflection is projected onto the principle plane of the objective lens to arrive at the CCD does not have a Gaussian beam profile. Therefore, it is necessary to convert it to a Gaussian beam profile before entering the basic plane.

In other words, spherical coordinates are used to explain the reflection of light on the surface before the objective lens (L2 lens), and orthogonal coordinates are used after the objective lens. In the two coordinates, 1 < / RTI > After that, the pattern of light is calculated centering on the spherical coordinates.

일 때

가 된다. 따라서 반사된 빔 프로파일의 최대 위치를 계산하여 표면의 기울기를 구할 수 있고, 이를 다시 XYZ 좌표로 바꾸어

,

를 계산해 줄 수 있다.When the maximum position of the incident beam profile is the Z-axis, the maximum position of the reflected beam profile is the surface normal

when

. Therefore, it is possible to calculate the slope of the surface by calculating the maximum position of the reflected beam profile, and then convert it into XYZ coordinates

,

Can be calculated.

라고 할 때 임의로 잡은

단면에서 표면이 이루는 각도를

로 근사하게 되며, 도 4를 통해 이 변수들을 나타내었다.Fig. 4 shows a change in the pattern of light when the surface is not plane but curvature. Even if the incident light is focused, the incident area of the light at the focal point does not become zero, which can be calculated through fourier optics. Therefore, when there is a curvature on the surface, the light focused on the measurement position is reflected on the surface having different inclination according to the incident position around the measurement position, and FIG. 4 shows this point as a picture. The surface slope at the measuring position is

When you say something randomly

The angle between the surface and the surface

, And these parameters are shown in FIG.

Figure 5 shows the incident and reflected beam profiles in terms of spherical coordinates. Since the beam profile initially set is a Gaussian shape, it is impossible to measure the diameter of incident light, but instead of the diameter, a portion where the intensity of the light falls from the center by a certain rate can be obtained.

에서

로 이동하며, 동시에 빔 프로파일이 곡률에 따라 찌그러지게 된다. 이 때문에 빛의 세기가 일정 비율만큼 떨어지는 등고선이 타원을 그리게 됨을 도시하였다.The left figure of FIG. 5 shows the Gaussian beam profile before incidence, and it can be seen that the diameter is circular. The figure on the right shows the beam profile after reflection,

in

And at the same time, the beam profile is distorted according to the curvature. For this reason, the contours in which the intensity of the light drops by a certain ratio are drawn in the ellipse.

,

,

항은 입사하는 빔 프로파일

와 반사하는 빔 프로파일

의 NA(numerical aperture) 차이를 이용하여 구한다. 측정 표면의 곡률이 볼록 렌즈 모양이면 반사되는 빛의 NA는 감소하며, 오목 렌즈 모양이면 NA가 증가한다.Next, the second partial differential

,

,

The term " incident beam profile "

And reflective beam profile

(Numerical aperture) difference of NA. If the curvature of the measurement surface is a convex lens shape, the NA of the reflected light decreases, and if it is a concave lens shape, the NA increases.

축과 늦게 변하는

축의

값을 구하면 이를 이용하여

의 2차 미분계수를 구할 수 있다.

값을 구하기 위해서는 입사하는 빛의 가우시안 빔 프로파일의 지름

와

, 그리고 반사되는 빔의 등고선의 장축 길이

와 단축 길이

가 필요하며, 도 5를 통해 이 변수들을 나타내었다.More specifically, in the reflected beam profile, the intensity of light is changed fast

Axis and Late Changes

largesse

When you get the value,

Can be obtained.

To obtain the value, the diameter of the Gaussian beam profile of incident light

Wow

, And the long axis length of the contour of the reflected beam

And short axis length

And these variables are shown in FIG.

를 원점으로 다시 놓으면 다음의 수학식 2와 같이 2개의 기본 곡률(principle curvature)

,

를 구할 수 있다.4 and 5 are summarized as follows. In a spherical gaussian beam profile reconstructed from a CCD

The two principal curvatures are obtained as shown in the following equation (2)

,

Can be obtained.

In Equation (2), d represents the diameter of the focal spot.

,

,

로 변환하여 수학식 3을 얻을 수 있다.After that,

,

,

To obtain Equation (3).

As described above, by simultaneously measuring various values such as the height value and the slope information at the measurement position and by profiling the lens, compared with the case of measuring only the position value at the measurement position of the conventional confocal microscope, The number can be reduced.

,

을 동시에 측정할 경우 렌즈 프로파일은 ATHANASIOS PAPOULIS의 'Generalized Sampling Expansion'을 이용하여 다음의 수학식 4와 같이 복원할 수 있다.Now, from the measurement position,

,

The lens profile can be restored as shown in Equation 4 using 'Generalized Sampling Expansion' of ATHANASIOS PAPOULIS.

Equation (4) is an approximate expression, and the lens profile can be restored by approximating using Equation (4). According to the embodiments of the present invention for simultaneously measuring the height value and the tilt information, when the number of measurement positions is the same, the band limit is twice as large as that in the case of restoring the lens profile using only the height value, Can be restored to the maximum.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, wherein like reference numerals refer to like elements throughout. Therefore, in the following embodiments, the configuration is focused on the different point from the embodiment of FIG. 1, and the configuration and operation are outlined for the same configuration in order to avoid duplication of description.

FIG. 6 is a view showing a confocal surface profiler using light sources of different wavelengths according to another embodiment of the present invention, wherein the surface measuring apparatus according to the embodiment of FIG. 1 uses one light source, 6 shows a device in which two detectors use two light sources of different wavelengths to use different focal spot sizes.

The plurality of light sources 11 and 12 generate light having different wavelengths and irradiate the sample 30 to be measured.

The input side dichroic filter 71 is a filter that filters the light sources 11 and 12 and the light sources 11 and 12 when the light sources 11 and 12 irradiate a plurality of light signals having different wavelengths through different incident paths. And is positioned between the sample (30) to selectively pass or reflect the plurality of light signals according to wavelengths, thereby controlling the light to be incident on the sample through one incident path.

The beam separating means 72 receives the light reflected from the sample 30 and divides the path of light into two. The beam splitter 72 may be implemented as an output-side Dichroic filter that receives the light reflected from the sample 30 and separates the path of light by wavelength.

The first detector 50 measures the height value for the sampling point of the sample by receiving the first light signal separated from the beam splitting means 72 and confirming the confocal.

The second detector 60 receives the second light signal separated from the beam splitting means 72 and detects the sample 30 from the second light signal at a time when the intensity of the first light signal becomes maximum, And the tilt information is measured with respect to the measurement position. Here, the tilt information preferably includes at least one of a surface tilt value with respect to the measurement position or a curvature indicating a degree of change of the tilt.

The first detector 50 and the second detector 60 function to improve the efficiency of curvature measurement by measuring incident light signals using different focal spot sizes.

7 is a view showing a confocal surface profiler using a light source in a polarized state according to another embodiment of the present invention, wherein the surface measuring apparatus according to the embodiment of FIG. 1 uses one light source, The surface measuring apparatus of FIG. 7 exemplifies a device in which two detectors simultaneously use different light sources of different polarization states to use different focal spot sizes.

The plurality of light sources 11 and 12 generate light having different polarization states to irradiate the sample 30 to be measured.

The polarization beam splitter 81 on the input side may be arranged such that when the light sources 11 and 12 irradiate a plurality of light signals having different polarization states through different incident paths, And the sample 30 to selectively pass or reflect the plurality of light signals in accordance with the polarization state so as to be incident on the sample through one incident path.

The beam separating means 82 receives the light reflected from the sample 30 and divides the path of the light into two. The beam splitting means 82 is preferably implemented as an output-side polarization beam splitter that receives the light reflected from the sample 30 and separates the progress path of light according to polarization states.

The first detector 50 measures the height value of the sample 30 at the sampling point by receiving the first light signal separated from the beam splitting means 82 and confirming the confocal.

The second detector 60 receives the second light signal separated from the beam splitting means 82 and detects the sample 30 from the second light signal at a time when the intensity of the first light signal becomes maximum, And the tilt information is measured with respect to the measurement position. Here, the tilt information preferably includes at least one of a surface tilt value with respect to the measurement position or a curvature indicating a degree of change of the tilt.

The first detector 50 and the second detector 60 function to improve the efficiency of curvature measurement by measuring incident light signals using different focal spot sizes.

FIG. 8 is a view for explaining a method of removing a misfit using an additional pin hole in a confocal surface profiler according to an embodiment of the present invention. In the embodiment of FIG. 8, the output side beam splitter 40 ) And the second detector (60).

More specifically, such a light eliminating means includes a first lens L4 for focusing a parallel second light signal separated from the output side beam splitter 40 as a focal point, a second lens L4 positioned at the focal point, a pinhole 2 for removing light appearing at a point other than the point L5 and a second lens L5 for converting a radial second light signal having passed through the focal point into parallel light and irradiating the light to the second detector 60 ) Can be sequentially provided.

9 is a diagram for illustrating a method and a sample scanning method for reducing polarization state dependence of light reflectance in a confocal surface profiler according to embodiments of the present invention.

First, to reduce the dependence of the light reflectance on the sample surface on the polarization state, a wave plate may be placed in front of the light source to convert the light incident on the surface into a circular polarization state. To this end, the surface measuring apparatus according to the embodiment of FIG. 9 is arranged in front of the light source 10 to convert the light irradiated on the sample 30 into a circularly polarized state, so that the light reflectance on the surface depends on the polarization state And a wave plate 15 for reducing the intensity of the incident light.

Second, various mechanical and optical means for changing / moving the measurement position of the sample can be utilized. To this end, the surface measuring apparatus according to the embodiment of FIG. 9 includes a 3-D stage 35 to which the sample 30 is attached to move the sample or a focal point on the sample 30 in the plane direction And may include at least one of a mirror scanner 37 to scan the sample. In particular, the mirror scanner 37 may be implemented by any one of a PZT mirror scanner, a galvanometer mirror, and a polygon mirror scanner. Advantageously, the scanning speed can be increased if a galvanometer mirror or a polygon mirror scanner other than the 3-D stage 25 is used to scan the sample as required by the implementation.

FIG. 10 is a flowchart illustrating a method of measuring a surface of a sample using a confocal surface profiler according to an embodiment of the present invention. Referring to FIGS. 1 and 6 to 9, So that each step is outlined around a time series sequence of operations in order to avoid redundancy of description.

In step S1010, the confocal surface profiler illuminates the sample to be measured with light generated from the light source.

In step S1020, the confocal surface profiler separates the path of light reflected from the sample into two by using an output-side beam splitter.

In step S1030, the confocal surface profiler measures a height value for a sampling point of the sample by receiving a first light signal separated from the beam splitter to confirm confocal, At the time when the intensity of the light signal reaches a maximum, the tilt information for the measurement position of the sample is simultaneously measured from the second light signal separated from the beam splitter. That is, it is possible to calculate the surface tilt and the higher-order partial differential term information of the surface from the light pattern of the second light signal, which changes according to the angle of the surface on which the light is focused at the measurement position of the sample. Here, the tilt information preferably includes at least one of a surface tilt value with respect to the measurement position or a curvature indicating a degree of change of the tilt.

In step S1040, the confocal surface profiler recovers a surface profile related to the sample based on the height value and the slope information measured through step S1030.

As described above, the conventional scanning confocal microscopy system must repeat a number of measurements in order to construct the surface profile of the entire sample due to the drawback that only the height value at each measurement position can not be obtained Which was particularly prominent in large-area samples.

However, according to the above-described embodiments of the present invention, not only the height value of the sample surface but also the tilt value and the secondary partial differential term can be measured at the same time, and the lens profile can be quickly recovered using the measured values, It is possible to significantly reduce the number of measurement positions required for the measurement.

In addition to the lens profile, it is possible to profile a large area of metal surface and a uniform dielectric with a relatively constant reflectance and a small spatial frequency, and at the same time obtain the slope and the secondary partial differential value at the measurement position . The obtained values can be used to reduce the number of measurement positions together with 'generalized sampling theorem'.

Furthermore, the cost of the CCD and beam splitter is relatively low compared to the objective lens, detector and 3-D stage, so that the confocal microscope system can do. Therefore, after the speed of the CCD is further improved, the application range and the market of the system proposed by the embodiments of the present invention are expected to be further expanded.

The present invention has been described above with reference to various embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

10, 11, 12: light source
15: wave plate
20: input-side beam splitter
30: sample (sample)
35: 3-D stage
37: mirror scanner
40: Output beam splitter
50: first detector
60: a second detector array
71: Input side dichroic filter
72: Output side dichroic filter
81: input side polarization beam splitter
82: Polarization beam splitter on the output side

Claims (20)

A light source for generating light and irradiating the sample to be measured;
An output side beam splitter for receiving the reflected light from the sample and separating the path of light into two;
A first detector for measuring a height value for a sampling point of the sample by receiving a first light signal separated from the beam splitter and confirming confocal; And
A second detector for receiving a second light signal separated from the beam splitter and for measuring tilt information of the sample from the second light signal at a time when the intensity of the first light signal is maximized; Comprising a surface measuring device. The method according to claim 1,
And a computing unit for restoring a surface profile related to the sample based on the height value measured through the first detector and the tilt information measured through the second detector. The method according to claim 1,
The tilt information may include:
And a curvature indicating a degree of change of a slope or a surface slope value with respect to the measurement position. The method according to claim 1,
And an input side beam splitter positioned between the light source and the sample and separating an incident path and a reflection path of light incident upon the sample and then reflected. The method according to claim 1,
A diverging lens positioned in front of the light source to convert the light radiated from the light source into parallel light and irradiate the parallel light to the sample;
An objective lens positioned in front of the sample to converge incident parallel light to a focal point on the sample; And
And a converging lens for converging a parallel first light signal positioned in front of the first detector to a focal point on the first detector through a pin hole. The method according to claim 1,
A step of scanning the sample with at least one of a 3-D stage on which the sample is attached and moving the sample, or a mirror scanner that moves the focus on the sample in a plane direction . The method according to claim 6,
The mirror scanner includes:
A PZT mirror scanner, a galvanometer mirror, or a polygon mirror scanner. The method according to claim 1,
Further comprising a light-eliminating means disposed between the output-side beam splitter and the second detector,
Wherein the light-
A first lens that focuses a parallel second light signal separated from the output side beam splitter as a focal point;
A pin hole positioned at the focal point and removing light appearing at points other than the focal point; And
And a second lens that converts the radial second light signal having passed through the focal point to parallel light and irradiates the second light to the second detector. The method according to claim 1,
And a wave plate positioned in front of the light source to reduce the degree of dependence of the light reflectance on the surface to the polarization state by converting the light irradiated to the sample into a circularly polarized state, . A plurality of light sources for generating light having different wavelengths to irradiate a sample to be measured;
Beam separating means for receiving the reflected light from the sample and separating the path of light into two;
A first detector for measuring a height value for a sampling point of the sample by receiving a first light signal separated from the beam splitting means and confirming confocal; And
A second detector for receiving a second light signal separated from the beam splitting means and measuring tilt information for a measurement position of the sample from the second light signal at a time when the intensity of the first light signal becomes maximum; And a surface-measuring device. 11. The method of claim 10,
When the light source irradiates a plurality of light signals having different wavelengths through different incident paths,
And an input side dichroic filter which is positioned between the light source and the sample to selectively pass or reflect the plurality of light signals according to wavelengths to thereby be incident on the sample through one incident path However,
Wherein the beam splitting means is implemented as an output-side Dichroic filter that receives light reflected from the sample and separates the path of light by wavelength. 11. The method of claim 10,
Wherein the first detector and the second detector enhance the efficiency of curvature measurement by measuring incident light signals using different focal spot sizes. 11. The method of claim 10,
The tilt information may include:
And a curvature indicating a degree of change of a slope or a surface slope value with respect to the measurement position. A plurality of light sources for generating light having different polarization states to irradiate a sample to be measured;
Beam separating means for receiving the reflected light from the sample and separating the path of light into two;
A first detector for measuring a height value for a sampling point of the sample by receiving a first light signal separated from the beam splitting means and confirming confocal; And
A second detector for receiving a second light signal separated from the beam splitting means and measuring tilt information for a measurement position of the sample from the second light signal at a time when the intensity of the first light signal becomes maximum; And a surface-measuring device. 15. The method of claim 14,
When the light source irradiates a plurality of light signals having different polarization states through different incident paths,
And an input side polarization beam splitter positioned between the light source and the sample for selectively passing or reflecting the plurality of light signals in accordance with a polarization state so as to be incident on the sample through one incident path, Including,
Wherein the beam splitting means is implemented as an output-side polarization beam splitter which receives the light reflected from the sample and separates the progress path of light according to polarization states. 15. The method of claim 14,
Wherein the first detector and the second detector enhance the efficiency of curvature measurement by measuring incident light signals using different focal spot sizes. 15. The method of claim 14,
The tilt information may include:
And a curvature indicating a degree of change of a slope or a surface slope value with respect to the measurement position. Irradiating light generated from a light source onto a sample to be measured;
Separating the traveling path of light reflected from the sample into two by using an output side beam splitter;
Measuring a height value of the sample with respect to a sampling point by receiving a first light signal separated from the beam splitter and confirming the confocal point, wherein when the intensity of the first light signal becomes maximum, Simultaneously measuring tilt information for a measurement position of the sample from the second light signal separated from the splitter; And
And restoring a surface profile related to the sample based on the measured height value and the slope information. 19. The method of claim 18,
The tilt information may include:
And a curvature indicating a degree of change of a slope or a surface slope value with respect to the measurement position. 19. The method of claim 18,
The step of simultaneously measuring the tilt information comprises:
Wherein the surface tilt and the higher order differential term information of the surface are calculated from a light pattern of the second light signal that changes in accordance with an angle of the surface on which the light is focused at the measurement position of the sample.

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