KR100631060B1 - Apparatus and method for measuring thickness and profile of transparent thin-film by white-light interferometry - Google Patents

Apparatus and method for measuring thickness and profile of transparent thin-film by white-light interferometry Download PDF

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KR100631060B1
KR100631060B1 KR20050092978A KR20050092978A KR100631060B1 KR 100631060 B1 KR100631060 B1 KR 100631060B1 KR 20050092978 A KR20050092978 A KR 20050092978A KR 20050092978 A KR20050092978 A KR 20050092978A KR 100631060 B1 KR100631060 B1 KR 100631060B1
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light
thin film
interference
thickness
information
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KR20050092978A
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Korean (ko)
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KR20060052004A (en
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김승우
김영식
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한국과학기술원
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Abstract

The present invention relates to an apparatus and method for measuring the thickness and shape of a transparent thin film using a white light interferometer. The present invention obtains a first interference pattern for each frequency after spectroscopy of the interference light by frequency, and obtains a second interference pattern for each frequency after spectroscopy of the synthesized interference light for each frequency. A phase generated due to the thickness of the thin film is obtained through the first interference pattern, and only thickness information of the thin film is obtained from the phase. The phase is obtained from the second interference pattern, and thin film surface information including thin film thickness information is obtained. Using the thin film thickness information, the surface information of the thin film is obtained from the thin film surface information including the thin film thickness information. Therefore, the present invention is capable of processing a point or a line by real time measurement and one measurement without a separate driving device, and has a strong effect on external vibration.
Scatter, interferometer, white light,

Description

Apparatus and method for measuring thickness and profile of transparent thin-film by white-light interferometry}

Figure 1a is a block diagram of a transparent thin film thickness and surface shape measurement apparatus using a conventional distributed white light scanning interference.

1B is a block diagram of a transparent thin film thickness and surface shape measuring apparatus using conventional white light scanning interference.

1C is a block diagram of a transparent thin film thickness and surface shape measuring apparatus using a conventional white light scanning interference and an acousto-optic modulation filter.

Figure 2a is a block diagram of a transparent thin film thickness and surface shape measuring apparatus using a white light interferometer according to a first embodiment of the present invention.

Figure 2b is a block diagram of a transparent thin film thickness and surface shape measurement apparatus using a white light interferometer according to a second embodiment of the present invention.

Figure 3a is a block diagram of a transparent thin film thickness and surface shape measurement apparatus using a white light interferometer according to a third embodiment of the present invention.

Figure 3b is a block diagram of a transparent thin film thickness and surface shape measurement apparatus using a white light interferometer according to a fourth embodiment of the present invention.

FIG. 3C is a view illustrating a process of making light into sheet light by applying the cylindrical lens of the embodiment of FIG. 3B; FIG.

Fig. 3D is information appearing on the CCD plane, where the X axis shows one line in the measurement area and the Y axis shows the light intensity distribution for each wavelength.

4 is a view showing a process of simultaneously calculating the thickness and surface shape information of the thin film according to the present invention.

5 is a view showing incident light, reflected light, and transmitted light with respect to a pattern (thin film) of one layer to be measured in the present invention.

6A is a light intensity distribution for each frequency obtained when frequency reflection of light reflected from one layer of thin film is performed (Fast Fourier Transform of Equation 6).

FIG. 6B is a light intensity distribution for each frequency obtained when only one component of several frequency components shown in FIG. 6A is filtered; FIG.

6C is a light intensity distribution for each frequency obtained when the equation 14 is FFTed.

FIG. 6D is a graph showing the inclination relationship between phases according to film thickness and wave count in calculating film thickness of a transparent thin film. FIG.

7 is a curve fitting of the refractive index change with the Cauchy equation according to the wavelength,

8A is a block diagram of a transparent thin film thickness and surface shape measurement apparatus using a white light interferometer according to a fifth embodiment of the present invention,

8B is a block diagram of a transparent thin film thickness and surface shape measuring apparatus using a white light interferometer and an automatic focusing apparatus according to a sixth embodiment of the present invention;

8c is a block diagram of a transparent thin film thickness and surface shape measurement apparatus using a white light interferometer according to a seventh embodiment of the present invention,

9 is a detailed configuration diagram of an imaging spectrometer applied to the above-described embodiments 5 to 8;

10 is a block diagram of a transparent thin film thickness and surface shape measurement apparatus using a white light interferometer according to an eighth embodiment of the present invention,

11A and 11B are diagrams for explaining a modified arrangement of the eighth embodiment.

* Explanation of symbols for main parts of the drawings

100: light source 120: first beam splitter

130: Michelson interference module 140: reflector

150: condenser lens 160: diffraction grating

170: CCD 180: measuring unit

The present invention relates to an apparatus and method for measuring the thickness and shape of a transparent thin film, and relates to an apparatus and method for measuring the thickness and shape of a transparent thin film using a distributed white light interferometer incorporating interferometry and spectrometry.

The measurement method which can measure thin film thickness and surface shape at the same time is still actively researched. In particular, research on distributed white light interferometers has been conducted since 1994, when J. Schwider and Liang Zhou outlined four-step gratings (J. Schwider, Liang Zhou, "Dispersive interferometric profilometer", Optics Letters, Vol. 19, No. 13, pp. 995 to 997), 1996 U. Schnell (U. Schnell, R. Danandr, S. Gray, "Dispersive white-light interferometry for absolute distance measurement with dielectric multilayer systems on the targer", Optics Letters , Vol. 21, No. 7, pp. 528 to 530), reported surface shape and thickness measurements for multilayer thin films.

1a shows a schematic diagram of a measurement system proposed by U. Schnell.

Figure 1a is a transparent thin film thickness and surface shape measurement apparatus using a conventional distributed white light scanning interference.

Referring to FIG. 1A, the white light emitted from the white light source 1 enters the prism 5 while passing through the lens 2, the light splitter 3, and the lens 4. The prism 5 reflects part of the incident white light and directs the remaining light to the measurement object 6. White light directed to the measurement object 6 is irradiated to the measurement surface of the measurement object 6 to which the thin film is applied. Here, the prism 5 simultaneously serves as a light splitter and a reference plane to generate an interference signal of light reflected from the measurement plane and the reference plane. This interference signal passes through the diffraction grating 7 and is separated into the interference signal for each wavelength of the white light source, and is detected by the detector 9 via the lens 8. Phase information for each wavelength is calculated from the interference signal detected by the detector 9, and the distance L with respect to the reference plane and the thickness d at the measurement point are measured through a search method with a mathematical phase model in the thin film. However, the method of FIG. 1A is a one-point measurement method, and distance L and thickness d are included in one interference signal, so it is not easy to separate the modes. Therefore, when measuring the thickness of the thick film (when the sizes of L and d are similar), the separation of L and d is difficult, and thus there is a disadvantage in that it is difficult to measure.

As another method, as shown in FIG. 1B, a method using a white light scanning interference method proposed by Kim in 1999 (Seung-Woo Kim, Gee-Hong Kim, "Thickness-profile measurement of transparent thin-film layers by white-light scanning interferometry ", Applied Optics, Vol. 38, No. 28, pp. 5968-5973)

The white light interference signal is composed of overlapping interference signals of various wavelengths constituting white light, and the interference signal of each wavelength includes information on thickness and shape as in the measurement principle of a distributed white light interferometer. By establishing an appropriate mathematical model of this information, the thickness and shape are simultaneously measured from the measurands, which were previously considered only error factors in conventional measurements. However, this method transfers the measurement object in the direction of the optical axis using a separate transfer device (hatched portion) to obtain the interference fringe, as shown in FIG.

As another method, as shown in FIG. 1C, three-dimensional shape information of the micro thin film layer is measured using an acoustic optical modulation filter. (Kim Soo-hyun, Kim Dae-seok, Kong Hong-jin, Yu Jang-woo, "Acoustic Optical Modulation Filter for Transparent Thin Films 3D shape measuring device ", Korean Patent Application No. 38873 (2002).

This will be described with reference to FIG. 1C.

The example of FIG. 1C is a structure in which a Michelson interferometer module having a built-in blocking surface and an acoustic optical modulation filter capable of scanning the visible spectral range are combined. Such a structure has an advantage of measuring thickness and surface shape information of a thin film independently by turning on / off a blocking surface.

As shown in FIG. 1C, the apparatus of FIG. 1C consists of a transparent micro thin film layer 83 applied over an opaque metal layer 82 pattern by applying an acoustic optical modulation filter (hereinafter abbreviated AOTF) 40 to a white light interference system. The measurement unit 80 of the multi-layer structure is a structure that can be measured independently by separating the information on the measurement thickness and information on the shape using the interference phenomenon of monochromatic light.

AOTF 40 is a kind of engineering band-pass filter, which acts as a diffraction grating for monochromatic light (hereinafter referred to as white light) incident on an acoustic optical crystal plane, and selects only a specific wavelength satisfying a condition. It is an optical filter with very narrow bandwidth.

The light source 10 to which white light is emitted is a tungsten-halogen lamp of about 70W, and one side of the single mode optical fiber 11 is connected in the emission direction to transmit the emitted white light to the other side of the optical fiber 11.

A fixing member 12 is positioned on the other side of the optical fiber 11, and the other side of the optical fiber 11 is correspondingly connected to a pinhole in the center. The white light emitted through the pinhole is spread around the pinhole.

At this time, it is positioned in the first convex lens 13 at a predetermined distance in the emission direction of the white light which is the front surface of the fixing member 12. The white light is aligned at a constant width while passing through the first convex lens 13. The white light transmitted through the first convex lens 13 is incident on the first beam splitter 20 positioned at a predetermined distance from the first convex lens 13. The first beam splitter 20 is in the form of a non-polarized cube capable of separating incident white light at a ratio of 50:50, and separation is sequentially performed according to a measurement process, not simultaneously.

Since the reflection angle of the first beam splitter 20 is about 45 ° with respect to the incident direction of the white light, the reflected white light is reflected perpendicularly to the incident direction. The second convex lens 31 is positioned corresponding to the reflection angle of the first beam splitter 20. The second convex lens 31 has a position opposite to that of the first convex lens 13. That is, in contrast to aligning the white light transmitted by the first convex lens 13 to have a constant width, focusing is performed so that the width of the transmitted white light is collected at one point along the direction of travel. The second beam splitter 32 is where the white light passing through the second convex lens 31 is collected at one point, that is, in focus. At this time, a part of the white light reaching the second beam splitter 32 is reflected toward the reference plane 33, and the other part is transmitted as it is and irradiated to the measuring unit 80.

At this time, the blocking plate 34 is positioned on the front surface of the reference surface 33 at a predetermined interval. Blocking play is parallel to each other at a position close to the reference plane 33, and selectively blocks the white light incident on the reference plane 33.

As such, the system consisting of the second convex lens 31, the second beam splitter 32, and the reference plane 33 is the Michelson interference module 30, and the blocking plate 34 is included in the blocking plate 34. Depending on the selective white light blocking), it operates in two modes.

In addition, the white light separated by the second beam splitter 32 and incident on the reference plane 33 and the measuring unit 80, respectively, causes a change in wavelength while being irradiated to the measuring unit 80.

This change is caused by having shape information and thickness information, and the respective information can be measured separately according to each mode according to the operation of the blocking plate 34.

The white light that has been irradiated in this way is reflected again and passes through the second beam splitter 32, and then the traveling width is aligned again while passing through the second convex lens 31. The first beam splitter 20 passes through the first beam splitter 20 and is incident on the AOTF 40 facing the second convex lens 31 with the first beam splitter 20 therebetween.

As mentioned earlier, the AOTF 40 selectively scans only a short wavelength of a specific band. The AOTF 40 used in this example has a non-collinear type, and the filtering range is about 400 nm to 650 nm. The resolution is about 1 nm to 5.1 nm.

The AOTF 40 filters only white light having an acoustic optical characteristic, that is, white light (or short wavelength light) of a band containing thickness information or shape information to be separated from white light of another band. The AOTF 40 is composed of an acoustic optical absorber, a driving device, and an acoustic optical crystal plane to which white light is irradiated. The crystal surface is composed of crystal crystals, and when the white light is irradiated, the refractive index changes by the acoustic wave generated by the driving device. Happens.

At this time, a moving three-dimensional diffraction grating is formed on the surface of the crystal plane, so that the irradiated white light hits the diffraction phenomenon. Then, a spectrum image of each wavelength, that is, a spectral image, can be obtained in parallel, and when white light separated through AOTF 40 is divided into + 1st and -1st order, -1st order is selected, and + The primary is extinguished by hitting and blocking the installed blocking member 60.

The CCD sensor 70 has a specification that the number of pixels is about 752 x 582, and one pixel size is about 11.1 mu m x 11.2 mu m. The third convex lens 50 is provided in the traveling direction of the white light thus selected. The white light passing through the third convex lens 50 is imaged by focusing and focusing the CCD sensor 70.

The white light formed on the CCD sensor 70 may be obtained as a spectral image, and the information may be extracted by scanning it. In addition, shape information on the surface of the micro thin film layer 83 in the measuring unit 80 may be finally obtained using the maximum point information obtained from each extracted information.

However, since the white light of a certain wavelength band is selected and measured using an acoustic optical modulation filter, the filtering range and resolution of the acoustic optical modulation filter have a great influence on the performance of the system, and the real-time measurement is a problem of selectively scanning short wavelengths of a specific band. Weak to external vibrations. In addition, in order to independently obtain the thickness and surface shape of the thin film, it is difficult to obtain both information at the same time because the blocking surface must be turned on / off by hardware. In addition, since a plurality of unknowns regarding the thickness and surface shape of the thin film are obtained by numerically analyzing wrist square fitting, there is a disadvantage in that the measurement time is very long.

Accordingly, an object of the present invention is a transparent using a white light interferometer that can simultaneously measure the thickness and surface shape of a single-layer transparent thin film for any one point using a distributed white light interferometer to solve the problems of the embodiments described above. An apparatus and method for measuring the thickness and shape of a thin film are provided.

The method for measuring the thickness and shape of a transparent thin film using a white light interferometer according to the present invention for achieving the above object is, in the method of obtaining the thickness information and the surface shape information of the thin film of the measuring object coated with the thin film, the white light Is made into polarized light in an arbitrary direction, and the first step of separating the horizontally polarized light and the vertically polarized light, and the horizontally polarized light (or vertically polarized light) is incident on the film-coated measuring object, and the vertically flat light (or horizontally Polarized light) is a second step of incident on the reference plane, the light incident on the measurement object is reflected in the upper and lower layers of the thin film to interfere with each other to generate interference light, and the reflected light by reflecting the light incident on the reference plane And a fifth step of spectroscopically interfering the interference light of the fourth step and the third step by combining the interference light of the third step and the third step to obtain an interference fringe for each frequency; Fourth step of obtaining the interference fringes by frequency after spectroscopy of the synthetic interference light of the fourth step, and obtain the phase generated by the thickness of the thin film through the interference fringes by frequency of the fifth step and from the phase The thin film thickness information obtained in the seventh step of obtaining only thickness information, the sixth step of obtaining a phase from the interference fringes of the sixth step, and obtaining the thin film surface information including the thin film thickness information, and the seventh step And a ninth step of obtaining only surface information of the thin film from the thin film surface information including the thin film thickness information obtained in the eighth step.

In addition, the method for measuring the thickness and shape of a transparent thin film using a white light interferometer according to the present invention is a method for obtaining the thickness information and the surface shape information of the thin film of the measurement object coated with a thin film, the light source for emitting white light The first step of dividing into two by applying a light splitter, and the white light of one of the two white light divided in the first step is incident on the measuring object coated with the thin film, and then interferes with the light reflected from the upper layer of the thin film and the lower layer of the thin film. A third step of acquiring the reflected light by injecting and reflecting the other white light of the two white lights divided in the first step and the second step of acquiring the light to the reference plane, and the interference light of the second step and the third step A fifth step of spectroscopy the interference light of the fourth step and the second step of combining the reflected light to generate the composite interference light for each frequency, and then obtaining the interference fringes for each frequency; Is obtained by spectroscopy by frequency and obtains the interference fringes by frequency, and obtains the phase from the interference fringes by the frequency of the fourth step. To obtain the surface information of the thin film including the thickness information of the thin film and from the thin film surface information including the thin film thickness information obtained in the eighth step by using the thin film thickness information obtained in the seventh step. It characterized in that it comprises a ninth step of obtaining only the surface information of the.

In addition, according to the present invention, the step of obtaining the phase from the interference fringe is a step of modeling the interference fringe by the equation (see Equation 6 when measuring the thickness of the single-layer thin film, see Equation 12 when measuring the shape of the single-layer thin film) And a cosine function consisting of a phase value containing thin film thickness and shape information by removing high frequency components to remove low frequency components contained in the interference fringes, and removing the envelope components from the interference regions from which the low frequency components are removed. After arranging (see Equation 8 for measuring the thickness of the monolayer thin film, and Equation 14 for measuring the shape of the monolayer thin film), Fast Fourier Transform, and taking only the positive frequency components, and then Inverse Fast Fourier Transforming the imaginary part so that the imaginary part becomes a phase value immediately after taking a natural log on the result of Inverse Fast Fourier Transform. Obtaining a phase value (see Equation 10 for measuring the thickness of a single-layer thin film, see Equation 16 for measuring the shape of a single-layer thin film), and the thickness of the thin film from the slope of the phase value according to the frequency and the refractive index N of the thin film. Obtaining a shape (refer to Equation 7 and Equations 17 to 19).

In addition, a device for measuring the thickness and shape of a transparent thin film using a white light interferometer according to the present invention is a device for measuring the thickness and surface shape of a thin film, a light source for emitting white light, and polarized white light in an arbitrary direction And a polarizing light splitter for splitting the polarized light into horizontally polarized light and vertically polarized light, and injecting the horizontally polarized light into a measuring object coated with a thin film, and then in the upper layer and the lower layer of the thin film. Acquire interference light with the reflected light, obtain the reflected light by injecting the vertically polarized light into the reference plane, and reflect the light. After obtaining the phase of the interference light, only the thin film thickness information is obtained from the phase, and the interference light and the reflected light. After obtaining the phase from the synthetic interference light obtained by interfering with the thickness information of the thin film from the phase of the synthetic interference light And obtaining surface information of the thin film, and obtaining thickness information of the thin film and surface information of the thin film from the surface information of the thin film including thin film thickness information obtained from the interference light and thin film thickness information obtained from the composite interference light. .

According to the present invention, a diffraction grating for spectroscopic light is obtained by spectroscopically interfering the interference light to obtain a phase from the interference light, and an image acquisition unit for acquiring the spectroscopic light. In order to obtain a phase from the synthesized interfering light, a 45 ° polarizing plate for obtaining the synthesized coherent light, a diffraction grating for spectroscopically diffracting the synthesized coherent light, and an image acquisition unit for acquiring the spectroscopic light are obtained. The phase information is obtained by applying image processing and an algorithm to the spectral light obtained from the synthetic interference light, thereby obtaining thickness information of the thin film and surface information of the thin film.

In addition, the apparatus for measuring the thickness and shape of a transparent thin film using a white light interferometer according to the present invention is a device for measuring the thickness and surface shape of any thin film, a light source for emitting white light, and a light splitter for dividing the white light Some white light divided by the optical splitter is incident to a measuring object coated with a thin film, and then interference light is obtained by light reflected from the upper layer and the lower layer of the thin film, and the remaining white light split from the optical splitter is a reference plane. After the incident to the reflection to obtain the reflected light but having a blocking plate that can block the reflected light, to obtain the phase of the interference light to operate the blocking plate to block the reflected light and then obtain the thin film thickness information by obtaining the phase from the interference light And removing the blocking plate to synthesize the interference light obtained by interfering the interference light with the reflected light. The surface information of the thin film including the thickness information of the thin film is obtained from the phase of the synthetic interference light after obtaining a phase from the phase, and the thin film thickness information obtained from the interference light and the thickness information of the thin film obtained from the composite interference light are obtained. The thickness information of the thin film and the surface information of the thin film may be obtained from the surface information.

In addition, according to the present invention, there is provided a diffraction grating to obtain a spectroscopic light by spectroscopy by frequency in order to obtain a phase from the interference light and the synthetic interference light, and an image acquisition unit for obtaining the spectroscopic light, and the spectroscopic light is processed into an image processing and algorithm By applying to obtain a phase, it is characterized in that the thickness information and the surface information of the thin film is obtained.

In addition, a device for measuring the thickness and shape of a transparent thin film using a white light interferometer according to the present invention is a device for measuring the thickness and surface shape of a thin film, a light source for emitting white light, and polarized white light in an arbitrary direction And a polarizing light splitter for splitting the polarized light into horizontally polarized light and vertically polarized light, and injecting the horizontally polarized light into a measuring object coated with a thin film, and then in the upper layer and the lower layer of the thin film. A diffraction grating which obtains the interference light with the reflected light, obtains the reflected light by injecting the vertical polarized light into the reference plane, and reflects the light, and obtains the spectroscopic light by spectroscopically analyzing the interference light to obtain a phase of the interference light; An image acquisition unit for acquiring the spectral light, and obtaining a phase by applying image processing and an algorithm to the spectral light; In order to obtain only the thin film thickness information from the image and obtain a phase from the synthetic interference light obtained by interfering the interference light and the reflected light, a diffraction spectrum is obtained by spectroscopically spectroscopically spectroscopy the 45 ° polarizing plate for obtaining the synthetic interference light and the synthetic interference light for each frequency. A grating and an image acquisition unit for acquiring the spectral light, and obtaining a phase of the spectral light obtained from the synthetic interference light by applying image processing and an algorithm, and then including the thickness information of the thin film from the phase of the synthetic interference light. And obtaining thickness information of the thin film and surface information of the thin film from the surface information of the thin film including the thin film thickness information obtained from the interference light and the thickness information of the thin film obtained from the composite interference light.

In addition, according to the present invention, a cylindrical lens is used to obtain the interference light, the reflected light and the composite interference light in the form of a line, and to obtain an interference pattern for each frequency from the line-shaped interference light and the line-shaped synthetic interference light. The cylindrical lens may be used to obtain thickness information of the thin film and surface information of the thin film.

In addition, the apparatus for measuring the thickness and shape of the transparent thin film using a white light interferometer according to the present invention is a light source for emitting white light, a polarizer for making white light polarized light in an arbitrary direction, and the polarized light perpendicular to the horizontal polarized light And a piezoelectric actuator for scanning and moving the measurement plane of the thin film in the optical axis direction, and a CCD for acquiring an interference fringe by an optical path difference. After incident on the coated workpiece, the interference light is obtained by the light reflected from the upper part of the thin film and the lower part of the thin film, and the reflected light is obtained by injecting and reflecting the vertically polarized light into the reference plane, and obtaining the phase of the interference light. After obtaining only the thin film thickness information from the phase, and obtaining the phase from the composite interference light obtained by interfering the interference light and the reflected light The surface information of the thin film including the thickness information of the thin film is obtained from the phase of the synthetic interference light, and the thickness of the thin film is obtained from the surface information of the thin film including the thickness information obtained from the interference light and the thickness information of the thin film obtained from the synthetic interference light. Information and surface information of the thin film is obtained.

In addition, according to the present invention, it comprises an imaging spectroscope for obtaining a wavelength-specific light intensity distribution for one line from the interference light and the synthetic interference light, by analyzing the light intensity distribution for each line for each line obtained from the image spectrometer, The thickness information and the surface information of the thin film is obtained.

In addition, according to the present invention, the device for measuring the thickness and shape of the transparent thin film is characterized in that it further comprises an automatic focusing device.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 2 to 11.

2 and 3 are embodiments of a transparent thin film thickness and surface shape measurement apparatus using a white light interferometer according to the present invention, the following embodiments are largely composed of the thickness measurement mode and the surface shape measurement mode of the thin film. The thin film thickness measurement mode analyzes interference light having an optical interference signal (thin film thickness information) due to the optical path difference reflected from the upper and lower layers of the thin film. In addition, the thin film surface shape measurement mode analyzes the composite coherent light having the optical interference signal (thin film shape information) due to the optical path difference reflected from the reference plane and the thin film, respectively.

FIG. 2A is a block diagram of a transparent thin film thickness and surface shape measuring apparatus using a white light interferometer according to a first embodiment of the present invention, and an example of obtaining thickness and surface shape information using a blocking surface built in a Michelson interferometer module. Explain.

The transparent thin film thickness and surface shape measuring apparatus using the white light interferometer of Figure 2a is a structure that can obtain the information on the measurement region in real time using the Michelson interferometer module 130, the condensing lens and the diffraction grating with a built-in blocking surface. Such a structure can measure thickness and surface shape information of a thin film independently by turning on / off a blocking surface.

The device of FIG. 2A is information about the measurement thickness and shape using the interference phenomenon of monochromatic light for the measurement unit 180 having a multilayer structure made of a transparent micro thin film layer (not shown) coated on an opaque metal layer (not shown) pattern. It is a structure that can be separated and measured independently.

The light source 100 is a tungsten-halogen lamp that emits white light, and one side of the single mode optical fiber 111 is connected in the emission direction to transmit the emitted white light to the other side of the optical fiber 111.

A fixing member 112 is positioned at the other side of the optical fiber 111, and the other side of the optical fiber 111 is correspondingly connected to a pinhole in the center. The white light emitted through the pinhole is spread around the pinhole.

At this time, it is positioned in the first convex lens 113 at a predetermined distance in the emission direction of the white light that is the front surface of the fixing member 112. The white light is emitted as parallel light having a constant width while passing through the first convex lens 113. The white light transmitted through the first convex lens 113 is incident on the first beam splitter 120 positioned at a predetermined distance from the first convex lens 113. The first beam splitter 120 is in the form of a non-polarized cube that can separate the incident white light at a ratio of 50:50, and the separation is sequentially performed according to a measurement process rather than being simultaneously performed.

Since the reflection angle of the first beam splitter 120 is about 45 ° with respect to the incident direction of the white light, the reflected white light is reflected perpendicularly to the incident direction. The second convex lens 131 is positioned corresponding to the reflection angle of the first beam splitter 120. The second convex lens 131 has a position opposite to that of the first convex lens 113. That is, unlike the first convex lens 113 emitting white light transmitted through the parallel light, the second convex lens 131 is focused so that the width of the transmitted white light is collected at one point along the traveling direction. . The second beam splitter 132 is where the white light passing through the second convex lens 131 is collected at one point, that is, the focus is focused. In this case, a part of the white light reaching the second beam splitter 132 is reflected toward the reference plane 133, and the other part is transmitted through the light as it is and is irradiated to the measuring unit 180.

At this time, the blocking plate 134 is positioned at the front of the reference surface 133 at a predetermined interval. The blocking plate 134 is parallel to each other at a position close to the reference plane 133, and selectively blocks white light incident on the reference plane 133.

As such, the system consisting of the second convex lens 131, the second beam splitter 132, and the reference plane 133 is the Michelson interference module 130, and the blocking plate 134 is included in the blocking plate 134. Depending on the selective white light blocking), it operates in two modes.

In addition, the white light separated by the second beam splitter 132 and incident on the reference plane 133 and the measurement unit 180, respectively, is irradiated to the measurement unit 180 to cause a change in wavelength. This change is caused by having shape information and thickness information, and the respective information can be measured separately according to each mode according to the operation of the blocking plate 134.

The white light irradiated as described above is reflected again and passes through the second beam splitter 132, and then passes through the second convex lens 131 to realign the traveling width to become parallel light. The light is reflected by the first beam splitter 120 and the reflector 140 and is incident on the condenser lens 150. And, the light passing through the condenser lens 150 hits the diffraction grating 160 and the diffraction phenomenon occurs. The white light diffracted while passing through the diffraction grating 160 is detected by the CCD 170 and obtained as an interference signal having thickness information and surface shape information of the thin film.

In other words, the process by mode, first, the white light split from the optical splitter 120 to obtain the thin film thickness information is incident on the measuring unit 180 coated with the thin film is reflected from the upper layer of the thin film and the lower layer of the thin film and interfering light The blocking plate 134 may be turned on to obtain the phase of the interference light and obtain only thickness information of the thin film. In order to obtain the shape information, the blocking plate 134 is turned off to interfere with the interference light reflected by the measurement unit 180 from the white light split by the light splitter 120 and the reflected light from the reference plane 133 to synthesize the coherent light. By obtaining the shape information of the thin film can be obtained. That is, the surface information of the thin film including the thickness information of the thin film is obtained from the phase of the synthetic interference light, and the thin film thickness information is obtained from the surface information of the thin film including the thin film thickness information obtained from the interference light and the thickness information of the thin film obtained from the synthetic interference light. Obtain thickness information and surface information of thin film.

In the step-by-step process, the white light source is divided into two by applying a light splitter, and one of the two white light beams is incident on a measuring unit coated with a thin film, and then reflected from the upper layer and the lower layer of the thin film. The interfering light is obtained from the light. The other white light of the divided white light is incident on the reference plane and then reflected to obtain reflected light. Here, the interference light and the reflected light are combined to generate a synthetic interference light.

Figure 2b is a block diagram of a device for measuring the thickness and shape of a transparent thin film using a white light interferometer according to a second embodiment of the present invention, by using the polarization of light to directly separate the thickness and surface shape information of the thin film in real time Measure with

2B illustrates that white light emitted from the light source 211 passes through the collimating lens 212 and becomes parallel light and is incident to the polarizer 213. The polarizer 213 serves to make the intensities of the light incident on the reference plane and the measurement plane similar to each other, and emits incident parallel light as light in an arbitrary polarization state. That is, the polarizer 213 matches the size of the horizontally and vertically polarized light equally, and the horizontally polarized light 214 and the vertically polarized light 215 are separated from each other to the measurement plane 252 and the reference plane 241. Incident. The interference signal formed by the thickness of the thin film on the measurement surface 252 is horizontally polarized light 214, and the horizontally polarized light 214 is reflected from the measurement surface 252 and exits as interference light, and the reference plane 241 is used. The light reflected by the light is vertically polarized light 215, and the vertically polarized light 215 emits reflected light from the reference plane 241. These two lights 214 and 215 are sequentially incident on the light splitters 221 and 261 through the light splitter 231. The light splitter 261 reflects the incident light and exits to the horizontal polarizer 271 for measuring the thickness of the thin film, and transmits the light to the polarizer 281 for the thin film shape measurement. The horizontal polarizer 271 passes only interference light, which is horizontally polarized light, and enters the diffraction grating 273 through the condenser lens 272. The diffraction grating 273 sends the spectroscopic light to the CCD 274 to obtain a wavelength-specific intensity distribution for a point. On the other hand, the polarizer 281 interferes with the reflected light of the horizontally polarized light 214 and the reflected light of the vertically polarized light 215 to obtain the composite coherent light, and transmits the light to the diffraction grating 283 to transmit the frequency at the CCD 284. Obtain spectroscopic spectroscopic light. After obtaining the phase of the spectral light obtained from the synthetic interference light by applying image processing and algorithm, the surface information of the thin film including the thickness information of the thin film is obtained from the phase of the synthetic interference light. The thickness information of the thin film and the surface information of the thin film are obtained from the surface information of the thin film including the thickness information of the thin film obtained from the light.

Looking at this process step by step, the white light is made of arbitrary polarized light, and then separated into horizontally polarized light and vertically polarized light, and the horizontal polarized light is incident on the thin film-coated measuring surface, and the vertically polarized light is incident on the reference plane. Then, the light incident on the measurement surface is reflected in the upper and lower layers of the thin film to interfere with each other to generate interference light, and reflect the light incident on the reference plane to generate reflected light. The interference light and the reflected light are combined to generate a synthetic interference light.

3A is a block diagram of an apparatus for measuring thickness and shape of a transparent thin film using a white light interferometer according to a third embodiment of the present invention.

The embodiment of FIG. 3A is a device system having the same configuration as the first embodiment of FIG. 2A described above, but the difference is that the condenser lens is replaced by cylindrical lenses 331 and 350. Since the remaining components perform the same function as the same reference numerals as in FIG. 2A, detailed description thereof will be omitted. 3A, the cylindrical lenses 331 and 350 extend the measurement area from one point to one line.

3B is a block diagram of an apparatus for measuring thickness and shape of a transparent thin film using a white light interferometer according to a fourth embodiment of the present invention.

The embodiment of FIG. 3B is of the same configuration as the second embodiment of FIG. 2B described above, but the difference is that the condenser lens is replaced with cylindrical lenses 342, 351, 372, 382. Since the remaining components perform the same function as the same reference numerals as in FIG. 2B, detailed description thereof will be omitted. 3B, the cylindrical lenses 342, 351, 372, and 382 extend the measurement area from one point to one line.

3C is a view illustrating a process of making light into sheet light using the cylindrical lens of the embodiment of FIGS. 2B and 3B. That is, the cylindrical lens of FIG. 3c makes the shape of light into sectional light at the position of P. FIG.

3D is information shown on the two-dimensional CCD plane, in which the X axis shows one line in the measurement area and the Y axis shows light intensity distribution for each wavelength. That is, when the measurement area is extended from one point to one line by the cylindrical lens used in the third to fourth embodiments, it appears on the CCD surface. Each pixel shown on the Y axis of the CCD shows a light intensity distribution for each wavelength.

Hereinafter, the thickness and the shape of the transparent thin film are measured using an interference signal obtained by the apparatus for measuring the thickness and the shape of the transparent thin film using the interferometer in the first to fourth embodiments described above with reference to FIGS. 4 to 8. How to do this in more detail.

The following interference signals refer to interference light and composite interference light.

4 is a view showing a process of simultaneously calculating the thickness and surface shape information of the thin film according to the present invention.

4 shows that the thickness information and the shape information of the thin film are separately obtained in the thin film structure, which is the measurement object, to finally obtain the surface shape and thickness information of the thin film. Shape information of the surface is represented by h and thickness information is represented by d.

FIG. 5 is a diagram illustrating incident light, reflected light, and transmitted light of a pattern (thin film) of one layer of the thin film, which is the measurement object of FIG. 4.

Referring to FIG. 5, when the light reflected from the upper layer of the thin film is E r1 , and the light reflected from the lower layer of the thin film is E r2 , E r3 , ..., the algorithm for calculating the thickness d of the thin film is as follows. It can be obtained from equations (1) to (11), and an algorithm for calculating the shape L of the thin film can be obtained from the following equations (12) to (19).

Briefly, the algorithm performs an FFT after removing unnecessary low frequency components by filtering high frequency filtering or the like with the interference signals (herein referred to as interference signals of interference light) obtained through the above-described apparatus. Then, IFFT is performed again to obtain only the phase value of the final interference fringe. At this time, since the thickness and the shape information of the thin film are included, the two values can be separated and obtained independently.

First, an algorithm for calculating the thickness d of the thin film will be described. The interference fringe equation of the interference signal of the interference light reflected from the upper layer portion and the lower layer portion of FIG.

[Equation 1]

Figure 112005512076448-pat00042

Where E r1 , E r2 , E r3,. , Are as shown in Equation 2 below.

[Equation 2]

Figure 112005512076448-pat00002

In this case, r ij , t ij denotes Fresnel reflection coefficient and transmission coefficient in the i, j layer, 2 is the amount of phase change experienced by the light traveling through the thin film having a thickness d as Is displayed.

[Equation 3]

β = 2kNdcosθ

Here, assuming θ = 0 °

β = 2 kNd

If the thin film is reversible, i.e. has a real refractive index

Figure 112005512076448-pat00043
Equation 4 can be applied simply because

[Equation 4]

Figure 112005512076448-pat00003

In order to express the equation of Equation 4 more simply

Figure 112005512076448-pat00044
If it can be expressed simply as in Equation 5.

[Equation 5]

Figure 112005512076448-pat00045

Substituting Equation 5 into Equation 1 and summarizing it is as in Equation 6.

[Equation 6]

Figure 112005512076448-pat00046

Looking at the equation (6) is completed the interference pattern to obtain the thickness of the thin film. That is, it can be seen that β containing the thickness information of the thin film is loaded as a repetitive frequency component of the cos function.

Using the relationship between β and d in Equation 3, the film thickness d can be expressed as Equation 7.

[Equation 7]

Figure 112005512076448-pat00006

Described as a β for equation (6) is a function of k to k FFT (Fast Fourier Transform) to the frequency-dependent light intensity distribution obtained shown in equation (3) it is also the same as 6a.

As shown in FIG. 6A, a value corresponding to the thickness d of the thin film is represented as a frequency component.

Figure 112005512076448-pat00047
Appears. So the signal is the strongest frequency component
Figure 112005512076448-pat00048
If only the components are filtered as shown in Figure 6b.

In addition, if the signal obtained in FIG. 6B is subjected to Inverse Fast Fourier Transform (IFFT), Equation 8 is obtained.

[Equation 8]

Figure 112005512076448-pat00007

If the FFT of the cosine function Equation 8 is again shown in FIG. 6C

Figure 112005512076448-pat00049
Wow
Figure 112005512076448-pat00050
If the frequency component is obtained and IFFT is performed by filtering only the positive frequency component, the signal obtained is shown in Equation (9).

[Equation 9]

Figure 112005512076448-pat00008

Taking the natural logarithm to Equation 9 is equal to Equation 10.

[Equation 10]

Figure 112005512076448-pat00009

If only the imaginary part is taken in Equation 10, a phase value β can be obtained.

And using the equation (7) to obtain the slope of the phase value β according to the wave number as shown in Figure 6d can be obtained the thickness d of the thin film. At this time, since d is affected by the refractive index N, the refractive index compensation should be performed to obtain the accurate thickness d.

Therefore, as shown in FIG. 7, when the refractive index N is curve-fitted using the Cauchy equation as shown in Equation 11 and the refractive index value according to the wave number is compensated by the Equation 7, the thin film thickness d considering the influence on dispersion can be obtained.

[Equation 11]

Figure 112005512076448-pat00010

In Equation 11, A, B, and C are constant values according to the refractive index curve of the material.

Next, the algorithm for calculating the surface shape L of the thin film is calculated by the same process as that of obtaining the thickness d described above, and the description thereof is as follows.

An interference signal generally obtained in the thin film surface shape measurement mode refers to synthetic interference light, and the interference fringe equation of the interference signal is expressed by Equation 12.

[Equation 12]

Figure 112005512076448-pat00011

A ( v ) is a low frequency component as a function of frequency distribution of a light source. Equation 12 is obtained by filtering and removing the low frequency component A ( v ) in Equation 12.

[Equation 13]

Figure 112005512076448-pat00012

Here, the component to be obtained

Figure 112005512076448-pat00051
Therefore, if you calculate and divide B ( v ) which is the envelope component of I , you can get Equation 14.

[Equation 14]

Figure 112005512076448-pat00052

Equation 14, the cosine function, is FFTed, and only the positive frequency component is extracted and IFFT is performed again.

[Equation 15]

Figure 112005512076448-pat00014

Taking the natural logarithm to Equation 15 is the same as Equation 16.

[Equation 16]

Figure 112005512076448-pat00053

If you take only the imaginary part in (16)

Figure 112005512076448-pat00054
You can get it easily.

Where phase component

Figure 112005512076448-pat00055
Is the same as Equation 17.

[Equation 17]

Figure 112005512076448-pat00056

At this time, δ ( d ) is the amount of phase change generated by the film thickness d

Figure 112005512076448-pat00057
Where n is the refractive index of the thin film.

Since δ ( d ) in Equation 17 is a known value measured in advance in the thickness measurement mode of the thin film, it can be easily separated from Equation 17 and expressed as Equation 18.

Equation 18

Figure 112005512076448-pat00058

Using the equation (18), the shape component L can be obtained as shown in the equation (19).

[Equation 19]

Figure 112005512076448-pat00018

Therefore, by using Equations 7 and 19, the thickness information d and the surface shape information L of the thin film can be easily obtained independently.

When the process is summarized in stages, the first interference pattern for each frequency is obtained after spectroscopy of the interference light by frequency, and the second interference pattern for each frequency is obtained after spectroscopy of the composite interference light for each frequency. A phase generated due to the thickness of the thin film is obtained through the first interference pattern, and only thickness information of the thin film is obtained from the phase. The phase is obtained from the second interference pattern, and thin film surface information including thin film thickness information is obtained. Using the thin film thickness information, the surface information of the thin film is obtained from the thin film surface information including the thin film thickness information.

8A is a block diagram of a transparent thin film thickness and surface shape measurement apparatus using a white light interferometer according to a fifth embodiment of the present invention.

The configuration of FIG. 8A differs from the configuration of the second embodiment of FIG. 2B in that the piezoelectric actuator 80 is mounted, and includes a CCD 84 so as to obtain an interference fringe due to the optical path difference. Then, the configuration including the CCDs 274 and 284 of the second embodiment of FIG. 2B for acquiring the interference light and the composite interference light is replaced with the imaging spectrometers 81 and 83. That is, in the second embodiment of FIG. 2B, the condenser lens 272, the diffraction grating 273, and the CCD 274 are replaced with the imaging spectrometer 81, the condenser lens 282 and the diffraction grating 283, and Replace the CCD 284 with an imaging spectrometer 83. Such imaging spectrometers 81 and 83 will be described below with reference to FIG.

The fifth embodiment of FIG. 8A performs the same operation for the same configuration as the second embodiment of FIG. 2B, and the piezoelectric actuator 80 scans and moves the measurement surface 252 in the optical axis direction to interfere with the optical path difference. A pattern can be obtained by the CCD 84. This fifth embodiment combines a white light scanning interferometry with a distributed white light interferometer (see the second embodiment described above). The white light scanning interferometry requires a transfer mechanism to continuously move the measurement object in the direction of the optical axis. . When the measurement object is transferred, the light intensity obtained from each light receiving element (ie, the imaging spectrometers 81 and 83) is a harmonic function wrapped in a sinc function, and it is detected that the light intensity reaches the maximum. For the precision of the measurement, the highly precise conveying device and position detection sensor are used for conveying the measuring object. The above-mentioned piezoelectric actuator (piezoelectric actuator) 80 is used as the transfer apparatus, and the transfer of nanometer resolution is possible. Position detectors are widely used as fixed capacitance or linear variable differential transformers (LVDTs). In addition, a method of estimating the position of the piezoelectric actuator from an input voltage applied to the piezoelectric actuator without a separate position detector is widely used. In this case, proper correction of hysteresis of the piezoelectric actuator is required. Combining by using the distance from the position detector at the point where the maximum light intensity is generated from each light receiving element can be configured to form a three-dimensional microstructure of the measurement object. As described above, when the white light is used, the shape measurement including all the steps within the stroke range of the piezoelectric actuator is possible without being limited by the step of the measurement object.

8B is a block diagram of a transparent thin film thickness and surface shape measuring apparatus using a white light interferometer according to a sixth embodiment of the present invention.

The sixth embodiment of FIG. 8B has the same configuration as the fifth embodiment described above, and performs the same function for the same configuration. However, the difference in configuration further configures the automatic focus control device 801. The auto focusing apparatus 801 generates a control signal from a focus error signal by detecting a confocal system using an optical fiber, a light source modulator for modulating the optical axis of the optical fiber ferrule, and light reflected from the surface of the measurement object. And a signal processing unit for acquiring a signal through a confocal system while moving a measurement object, and obtaining a focus position by obtaining a differential result of the acquired signal. The automatic focus control device 801 is a prior application (Korean Patent Application No. 10-2004-51788) by the inventor of the present invention, detailed description thereof will be omitted. When the interferometer according to the sixth embodiment is further configured by configuring the auto focus control device 801, the surface information of the thin film is obtained from the thin film surface information including the existing thin film thickness information and the thin film thickness information, and the automatic focus control is performed. It may also include functionality.

8C is a block diagram of a transparent thin film thickness and surface shape measurement apparatus using a white light interferometer according to a seventh embodiment of the present invention.

The seventh embodiment of FIG. 8C has the same configuration as the fifth embodiment described above, and performs the same function for the same configuration. However, in order to simplify the configuration, the configuration of the light splitter (the light splitter 221 of FIG. 2B) is omitted. That is, the interference light from the measurement plane 252 and the reflected light from the reference plane 241 are incident on the light splitter 261 through the light splitter 231 and reflected or transmitted through the light splitter 231 to make one line in the imaging spectrometers 81 and 83. Obtain the intensity distribution for each wavelength for. That is, the polarizer 213 separates the horizontally polarized light 214 and the vertically polarized light 215 and enters the measurement plane 252 and the reference plane 241, respectively. At this time, the horizontally polarized light passing through the λ / 4 plate 92 is reflected by the measurement surface 252 and then passes through the λ / 4 plate 92 again and is emitted as interference light that is vertically polarized. The vertically polarized light passing through 91 is reflected by the reference plane 241 and then passes through the λ / 4 plate 91 to be emitted as horizontally polarized reflected light. The two lights 214 and 215 are incident on the splitter 261 again through the splitter 231 and the splitter 261 reflects the incident light so as to transmit only vertically polarized light for thin film thickness measurement. The light emitted toward the configured horizontal polarizer 271 and transmitted through the light splitter 261 exits toward the polarizer 281 configured to transmit a part of the horizontal polarized light and a part of the vertically polarized light for thin film shape measurement. The vertical polarizer 271 passes only interference light, which is vertically polarized light, to obtain intensity distribution for each wavelength of one line in the imaging spectrometer 81. On the other hand, the polarizer 281 obtains the composite interference light by interfering with the interference light which is horizontally polarized light 214 and the reflected light which is vertically polarized light 215. From this synthesized interference light, the intensity distribution for each wavelength for one line in the imaging spectrometer 83 is obtained. Therefore, the thickness information of the thin film and the surface information of the thin film are obtained from the surface information of the thin film including the thin film thickness information obtained from the interference light and the thickness information of the thin film obtained from the synthetic interference light.

9 is a detailed configuration diagram of an imaging spectrometer applied to the above-described fifth to seventh embodiments.

Referring to FIG. 9, the imaging spectrometer used in the fifth to seventh embodiments described above is for obtaining wavelength-specific light intensity distribution for one line in the region 1100 to which the measuring beam is irradiated. That is, the slit 1400 is moved up and down from the light passing through the collimating lens 1300 in the measurement line 1200 in the measurement beam irradiation area 1100. The light passing through the slit 1400 corresponding to the selected measurement line 1200 is a wavelength of one line in the CCD 1800 through the collimating lens 1500, the dispersion plate 1600, and the condenser lens 1700. Star light intensity distribution can be obtained. By analyzing this, thickness information and surface information may be obtained from surface information including thickness information and thickness information of one line.

10 is a block diagram of a transparent thin film thickness and surface shape measurement apparatus using a white light interferometer according to an eighth embodiment of the present invention.

The eighth embodiment of FIG. 10 performs the same operation with respect to the same configuration as the fifth embodiment of FIG. 8A described above, and thus a detailed description thereof will be omitted.

Referring to FIG. 10 compared with FIG. 8A, the piezoelectric driver of FIG. 8A is omitted in the dotted box D including the measurement surface 252, and the interference due to the optical path difference is omitted as the piezoelectric driver is omitted. The CCD for obtaining a pattern is eliminated and consists of two CCDs 81 and 83.

11A and 11B are diagrams for explaining a modified arrangement of the eighth embodiment. .

FIG. 11A is a modified portion of the dotted box D of FIG. 10 by replacing the dotted box D1 with a dotted line box Dl, and constitutes a mirror interference objective lens system M1 inside the dotted box D1.

FIG. 11B is modified by replacing the dotted box D of FIG. 10 with the dotted box D2, and the Michelson interference objective lens system M2 is formed inside the dotted box D2.

The objective lens systems M1 and M2 include a reference plane and a polarized light splitter, and such a configuration is well known to those skilled in the art, and thus a detailed description thereof will be omitted.

In addition, in the above-described embodiments of the present invention, the light intensity distribution for each wavelength is obtained for the point and the line, but AOTF (Acousto-A) for obtaining the light intensity distribution for each wavelength for one area from the interference light and the synthetic interference light is obtained. Analyze the wavelength intensity of the thin film and the surface information of the thin film by analyzing the light intensity distribution by the wavelength of the area obtained from the image spectrometer, including a spectroscope that can image an area such as an optical tunable filter (LCT) or a liquid crystal tunable filter (LCTF). It is also possible to obtain.

Therefore, the present invention is characterized in that it is possible to process one point by real time measurement and one measurement without a separate driving device, and is robust to external vibration. In addition, by using the blocking surface of the Michelson interferometer module or by polarizing light, it is possible not only to independently extract information about the thickness and surface shape of a single layer thin film, but also to maintain a high measurement resolution.

Claims (12)

  1. In the method for obtaining the thickness information and the surface shape information of the thin film of the measuring object coated with the thin film,
    A first step of making white light into polarized light in an arbitrary direction and separating the white light into horizontally polarized light and vertically polarized light;
    A second step of injecting horizontally polarized light (or vertically polarized light) into the measuring object coated with the thin film and vertically polarized light (or horizontally polarized light) to the reference plane;
    A third step of interfering with the light incident on the measurement object reflected from the upper and lower portions of the thin film to generate interference light;
    A fourth step of reflecting the light incident on the reference plane to obtain reflected light and combining the interference light of the third step to generate a synthetic interference light;
    A fifth step of spectroscopy the interference light of the third step for each frequency and then obtain an interference fringe for each frequency;
    A sixth step of obtaining the interference fringes for each frequency after spectroscopy of the synthesized interference light of the fourth step for each frequency;
    A seventh step of obtaining a phase generated by the thickness of the thin film through the frequency-specific interference fringes of the fifth step and obtaining only thickness information of the thin film from the phase;
    An eighth step of obtaining a phase from the interference fringes for each frequency of the sixth step and obtaining thin film surface information including the thin film thickness information; And
    And a ninth step of obtaining only surface information of the thin film from the thin film surface information including the thin film thickness information obtained in the eighth step using the thin film thickness information obtained in the seventh step. And a method of measuring the shape.
  2. In the method for obtaining the thickness information and the surface shape information of the thin film of the measuring object coated with the thin film,
    A first step of dividing the light source emitting white light into two by applying a light splitter;
    A second step of injecting white light of one of the two white lights divided in the first step into a measurement object coated with a thin film and then obtaining interference light with light reflected from an upper layer and a lower layer of the thin film;
    A third step of obtaining reflected light by injecting and reflecting the other white light of the two white light divided in the first step into a reference plane;
    A fourth step of combining the interference light of the second step and the reflected light of the third step to generate a synthetic interference light;
    A fifth step of spectroscopy the interference light of the second step for each frequency and then obtain an interference fringe for each frequency;
    A sixth step of obtaining the interference fringes for each frequency after spectroscopy of the synthesized interference light of the fourth step for each frequency;
    A seventh step of acquiring only thin film thickness information by obtaining a phase from the frequency-dependent interference fringe of the fourth step;
    An eighth step of obtaining the surface information of the thin film including the thickness information of the thin film by obtaining a phase through the interference fringe of the sixth step; And
    And a ninth step of obtaining only surface information of the thin film from the thin film surface information including the thin film thickness information obtained in the eighth step using the thin film thickness information obtained in the seventh step. And a method of measuring the shape.
  3. The method of claim 1 or 2, wherein obtaining the phase from the interference fringe is
    Modeling the interference fringe by the equation (refer to Equation 6 when measuring the thickness of the single-layer thin film, and by using Equation 12 when measuring the shape of the single-layer thin film);
    High frequency filtering to remove low frequency components contained in the interference fringe;
    Removing the envelope component from the interference fringes from which the low frequency component has been removed and arranging it by a cosine function including only a phase value containing the thickness and shape information of the thin film (refer to Equation 8 when measuring the thickness of the single layer thin film) When measuring the shape of the equation (14);
    Fast Fourier Transform the summed cosine function to take only positive frequency components, and then Inverse Fast Fourier Transform;
    Obtaining the phase value after taking the natural log on the result of the Inverse Fast Fourier Transform and transforming the imaginary part to be the phase value immediately (see Equation 10 when measuring the thickness of the single-layer thin film. (16);
    Obtaining a thickness and a shape of the thin film from the slope of the phase value according to the frequency and the refractive index N of the thin film (refer to Equations 7 and 17 to 19); measuring the thickness and shape of the transparent thin film, including How to.
  4. In the apparatus for measuring the thickness of the arbitrary thin film and the surface shape of the thin film
    A light source for emitting white light, a polarizing device for making white light polarized light in an arbitrary direction, and a polarized light splitter for separating the polarized light into horizontally polarized light and vertically polarized light, and coating the horizontally polarized light with a thin film. After entering the measurement object, the interference light is obtained by the light reflected from the upper layer and the lower layer of the thin film, the vertically polarized light is incident on the reference plane and then reflected to obtain the reflected light, and the phase of the interference light is obtained. Obtain only the thin film thickness information from the phase, obtain a phase from the composite interference light obtained by interfering the interference light and the reflected light, and obtain surface information of the thin film including the thickness information of the thin film from the phase of the synthetic interference light, From the surface information of the thin film containing the thin film thickness information obtained from the Apparatus for measuring the thickness and shape of a transparent thin film, characterized in that obtaining the thickness information and the surface information of the thin film.
  5. The method according to claim 4,
    In order to obtain a phase from the interference light, a diffraction grating for spectroscopically obtaining the spectroscopic light by spectroscopy of the interfering light, and an image acquisition unit for acquiring the spectroscopic light, and applying the image processing and an algorithm to the spectroscopic light to obtain a phase. And a 45 ° polarizing plate for obtaining the synthetic interference light, a diffraction grating for obtaining the spectral light by frequency spectroscopy of the synthetic interference light, and an image acquisition unit for acquiring the spectral light to obtain a phase from the synthetic interference light. Apparatus for measuring the thickness and shape of a transparent thin film, characterized in that to obtain the thickness information of the thin film and the surface information of the thin film by obtaining a phase by applying the image processing and algorithm to the spectroscopic light obtained from the light.
  6. In the apparatus for measuring the thickness of the arbitrary thin film and the surface shape of the thin film
    It consists of a light source for emitting white light and a light splitter for dividing the white light, and the part of the white light split from the light splitter is incident on the measuring object coated with a thin film and then interfering with light reflected from the upper layer of the thin film and the lower layer of the thin film. Acquisition of the light splitter, and the remaining white light divided by the optical splitter is incident to the reference plane and reflected to obtain a reflected light, but has a blocking plate that can block the reflected light, and operates the blocking plate to obtain the phase of the interference light to generate the reflected light. After blocking, obtain the thin film thickness information by obtaining a phase from the interference light, obtain a phase from the composite interference light obtained by interfering the interference light and the reflected light by removing the blocking plate, and then obtain the thickness information of the thin film from the phase of the synthetic interference light. Acquires surface information of a thin film including a thin film and sums the thin film thickness information obtained by the interference light. Transparent foil apparatus for measuring the film thickness and shape, characterized from the interference light from the surface information of the film with the thickness information of the thin film obtained to acquire information of the surface with a thin film thickness information of the thin film.
  7. The method according to claim 6
    In order to obtain a phase from the interference light and the synthetic interference light, a diffraction grating for spectroscopic light is obtained by frequency spectroscopy, and an image acquiring unit for acquiring the spectroscopic light. Obtaining the thickness information and the surface information of the thin film by obtaining the device for measuring the thickness and shape of the transparent thin film.
  8. In the apparatus for measuring the thickness of the arbitrary thin film and the surface shape of the thin film
    A light source for emitting white light, a polarizing device for making white light polarized light in an arbitrary direction, and a polarized light splitter for separating the polarized light into horizontally polarized light and vertically polarized light, and coating the horizontally polarized light with a thin film. After entering the measurement object, the interference light is acquired by the light reflected from the upper layer and the lower layer of the thin film, the vertical polarized light is incident on the reference plane and then reflected to obtain the reflected light, and the interference is obtained to obtain the phase of the interference light. A diffraction grating for spectroscopic light by spectroscopically diffracting light and an image acquiring unit for acquiring the spectroscopic light, and after obtaining a phase by applying image processing and an algorithm to the spectroscopic light, obtaining only thin film thickness information from the phase 45 ° piece which obtains the synthesized interference light to obtain a phase from the synthesized interference light obtained by interfering the interference light with the reflected light. A plate and a diffraction grating for obtaining spectroscopic light by spectroscopically spectroscopy the synthesized interference light and an image acquisition unit for acquiring the spectroscopic light. Then, the surface information of the thin film including the thickness information of the thin film is obtained from the phase of the synthetic interference light, and the thin film thickness information is obtained from the surface information of the thin film including the thickness information of the thin film obtained from the interference light and the thickness information of the thin film obtained from the synthetic interference light. Apparatus for measuring the thickness and shape of the transparent thin film, characterized in that to obtain the thickness information and the surface information of the thin film.
  9. The method according to any one of claims 4, 6 and 8
    A cylindrical lens is used to obtain the interference light, the reflected light, and the synthesized interference light in the form of a line, and a cylindrical lens is used to obtain an interference pattern for each frequency from the line-shaped interference light and the line-shaped synthesized interference light. Apparatus for measuring the thickness and shape of a thin film, characterized in that for obtaining the thickness information and the surface information of the thin film.
  10. In the apparatus for measuring the thickness of the arbitrary thin film and the surface shape of the thin film
    A light source for emitting white light, a polarizer for making white light polarized light in an arbitrary direction, a polarized light splitter for separating the polarized light into horizontally polarized light and vertically polarized light, and a measurement plane of the thin film in the optical axis direction It consists of a piezoelectric actuator for moving and a CCD for acquiring the interference fringes due to the optical path difference, and the horizontal polarized light is incident on the measuring object coated with the thin film, and then interferes with the light reflected from the upper layer of the thin film and the lower layer of the thin film. Acquisition of light, reflection of the vertically polarized light incident on a reference plane, and reflection to obtain reflected light, after obtaining the phase of the interference light, only the thin film thickness information is obtained from the phase, and the interference obtained by interfering with the reflected light After obtaining the phase from the interference light and obtaining the surface information of the thin film including the thickness information of the thin film from the phase of the synthetic interference light, Measuring the thickness and shape of the transparent thin film, wherein the thickness information of the thin film and the surface information of the thin film are obtained from the surface information of the thin film including the thin film thickness information obtained from the interference light and the thin film thickness information obtained from the synthetic interference light. Device.
  11. The method according to claim 10,
    It includes an imaging spectroscope for obtaining a light intensity distribution for each line for one line from the interference light and the synthetic interference light, by analyzing the light intensity distribution for each line obtained by the image spectrometer, the thickness information and thin film Apparatus for measuring the thickness and shape of a transparent thin film, characterized in that to obtain the surface information of.
  12. The method according to claim 11,
    The apparatus for measuring the thickness and shape of the transparent thin film
    Apparatus for measuring the thickness and shape of the transparent thin film further comprising an automatic focusing device.
KR20050092978A 2004-11-10 2005-10-04 Apparatus and method for measuring thickness and profile of transparent thin-film by white-light interferometry KR100631060B1 (en)

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KR100941981B1 (en) * 2007-11-06 2010-02-11 한국표준과학연구원 Laser interferometric mekometer
KR100922142B1 (en) * 2007-11-12 2009-10-19 한국표준과학연구원 Apparatus for realtime film thickness monitoring using phase difference of polarized laser and the method thereof
KR101218077B1 (en) 2012-10-31 2013-01-03 서울과학기술대학교 산학협력단 Dual cavity optical fiber sensor system using algorithm of phase compensation
KR101464695B1 (en) * 2013-05-03 2014-11-27 (주)프로옵틱스 Multi-interference phase interferometer with simultaneous measurement functions
KR101554203B1 (en) 2013-07-05 2015-09-21 한국표준과학연구원 Thickness Measuring Apparatus and Thickness Measuring Method
KR101650319B1 (en) * 2015-03-06 2016-08-24 에스엔유 프리시젼 주식회사 Method and Apparatus for measuring thickness using color camera
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