KR101788450B1 - Apparatus and method for inspecting thickness of transparent thin film using terahertz wave - Google Patents

Apparatus and method for inspecting thickness of transparent thin film using terahertz wave Download PDF

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KR101788450B1
KR101788450B1 KR1020160031922A KR20160031922A KR101788450B1 KR 101788450 B1 KR101788450 B1 KR 101788450B1 KR 1020160031922 A KR1020160031922 A KR 1020160031922A KR 20160031922 A KR20160031922 A KR 20160031922A KR 101788450 B1 KR101788450 B1 KR 101788450B1
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thickness
thin film
terahertz wave
transparent thin
measuring
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KR20170108281A (en
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윤일구
신동석
최현용
인치훈
김재석
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연세대학교 산학협력단
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/30—Accessories, mechanical or electrical features
    • G01N2223/345—Accessories, mechanical or electrical features mathematical transformations on beams or signals, e.g. Fourier

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  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

An apparatus for measuring the thickness of a transparent thin film is disclosed. The apparatus for measuring the thickness of a transparent thin film according to the present embodiment includes a terahertz wave detecting apparatus for detecting a terahertz wave transmitted through a measurement target by generating a terahertz wave, a first terahertz wave detected through the transparent substrate, A second thickness measurement unit for measuring a first thickness of the transparent substrate by using the second thickness measurement unit and a second terahertz wave detected through the transparent thin film formed on the transparent substrate and measuring a second thickness of the transparent thin film using the first thickness And a second thickness measuring unit.

Figure R1020160031922

Description

TECHNICAL FIELD [0001] The present invention relates to an apparatus for measuring the thickness of a transparent thin film using a terahertz wave and a method of measuring the thickness of the transparent thin film using the terahertz wave.

Embodiments of the present invention relate to an apparatus and method for measuring the thickness of a transparent thin film using a terahertz wave.

In recent years, there has been a growing demand for transparent, flexible and large-area displays in the display market. In order to realize such a display, the elements or layers constituting the display are made of a transparent material and are layered in a thinner form. Therefore, since the thickness of the transparent thin film contained in the element or layers is one of the factors that can determine the display quality, the thickness of the transparent thin film must be precisely measured.

Scanning electron microscopy (SEM), transmission electron microscope (TEM), surface profiler (alpha-step) and AFM (atomic force microscopy) Ellipsometer and Reflectometer.

Electron microscopy and scanning probe method are methods of measuring the thickness by physical contact with the thin film, which can damage the thin film or break the thin film. Further, in the optical system, when thin films having similar or identical optical characteristics are overlapped, it is impossible to measure the thickness of the thin film.

Also, although a transparent thin film used for a large-area display can also be manufactured in a large area, it is difficult to measure the thickness of a transparent thin film having a large area by the above-described methods.

Korean Patent Laid-Open Publication No. 2015-0004146, "Inspection Apparatus Using Terahertz" Korean Patent Laid-Open Publication No. 2014-0031070, "Non-Contact Thickness Measuring Apparatus and Method for Measuring Thickness of It"

 Anis Rahman and Aunik K. Rahman, "Effective testing for wafer reject minimization by terahertz analysis and sub-surface imaging ", Advanced Semiconductor Manufacturing Conference (ASMC), 19-21 May 2014. 25th Annual SEMI

It is an object of embodiments of the present invention to provide an apparatus and method for measuring the thickness of a transparent thin film formed on a transparent substrate in a non-contact manner using a terahertz wave.

It is another object of embodiments of the present invention to provide a method and apparatus for monitoring the uniformity of thickness in real time by measuring the thickness of a transparent thin film while moving a position of a terahertz wave irradiated on the transparent substrate or transparent thin film, And a method of measuring the same.

An apparatus for measuring the thickness of a transparent thin film according to an embodiment includes a terahertz wave detecting apparatus for detecting a terahertz wave transmitted through a measurement target by generating a terahertz wave, a first terahertz wave detected through the transparent substrate A first thickness measuring unit for measuring a first thickness of the transparent substrate, a second THz wave detected by transmitting a transparent thin film formed on the transparent substrate, and a second THz wavelength measured using the first thickness, And a second thickness measuring unit for measuring the thickness of the second substrate.

According to an embodiment, the apparatus for measuring the thickness of the transparent thin film may further include a storage unit for storing the detected first and second THz waves, and the first thickness.

According to an embodiment, the first thickness measuring unit may measure the first thickness by the following equation.

Figure 112016025630412-pat00001

Here, D 1 is the first thickness, c is the speed of light, n 1 is the refractive index of the transparent substrate, and Δf 1 is the resonance frequency interval of the first THz wave detected through the transparent substrate.

According to the embodiment, the second thickness measuring unit may measure the second thickness by the following equation.

Figure 112016025630412-pat00002

Here, D 2 is the second thickness, n 2 is the refractive index of the transparent thin film, f 2 is the resonance frequency interval of the second terahertz wave detected through the transparent substrate and the transparent thin film, n 1 is the transparent The refractive index of the substrate, D 1, is the first thickness.

According to the embodiment, the apparatus for measuring the thickness of the transparent thin film may further include an input unit for receiving the refractive index of the transparent substrate, the refractive index of the transparent thin film, and the speed of the light.

According to an embodiment of the present invention, the terahertz wave detecting apparatus includes a laser beam generator for generating a femtosecond laser beam, a beam splitter for separating the femtosecond laser beam into a first beam and a second beam, A second ZnTe crystal that receives the second beam, and a second ZnTe crystal that transmits the terahertz wave transmitted through the second ZnTe crystal and the second ZnTe crystal that transmits the second ZnTe crystal, And a detector for detecting an electric field intensity of the terahertz wave transmitted through the measurement object using the second beam.

According to the embodiment, the apparatus for measuring the thickness of the transparent thin film may further include an input unit for receiving a movement control command. Here, the terahertz wave detecting apparatus moves the first ZnTe crystal, the reflection mirror and the second ZnTe crystal toward at least one of the x-axis, the y-axis and the z-axis according to the movement control command, The terahertz wave transmitted through the object can be detected.

According to the embodiment, the first thickness measuring unit may measure the first thickness of the transparent substrate according to the detection position of the first terahertz wave using the first terahertz wave that is moved in the transparent substrate and detected have.

According to the embodiment, the second thickness measuring unit may measure the second thickness of the transparent thin film according to the detection position of the second terahertz wave using the second terahertz wave that is moved in the transparent thin film and detected have.

According to the embodiment, the apparatus for measuring the thickness of the transparent thin film may further include a display unit for displaying a second thickness of the transparent thin film according to the detection position of the second terahertz wave.

According to an embodiment, the transparent substrate may be formed of any one of poly-ethylene-terephthalate (PET), poly-carbonate (PC), and polyimide (PI).

Meanwhile, a method of measuring the thickness of a transparent thin film according to an embodiment of the present invention includes: measuring a first thickness of the transparent substrate using a first terahertz wave transmitted through the transparent substrate; And measuring a second thickness of the transparent thin film by using the first thickness.

According to the embodiment, the step of measuring the first thickness may measure the first thickness by the following equation.

Figure 112016025630412-pat00003

Here, D 1 is the first thickness, c is the speed of light, n 1 is the refractive index of the transparent substrate, and Δf 1 is the resonance frequency interval of the first THz wave detected through the transparent substrate.

According to the embodiment, the step of measuring the second thickness may measure the second thickness by the following equation.

Figure 112016025630412-pat00004

Here, D 2 is the second thickness, n 2 is the refractive index of the transparent thin film, f 2 is the resonance frequency interval of the second terahertz wave detected through the transparent substrate and the transparent thin film, n 1 is the transparent The refractive index of the substrate, D 1, is the first thickness.

According to embodiments of the present invention, the thickness of a transparent thin film formed on a transparent substrate in a non-contact manner using a terahertz wave can be measured without damaging the transparent substrate and the transparent thin film.

In addition, according to embodiments of the present invention, the thickness uniformity of the transparent thin film can be monitored in real time by measuring the thickness of the transparent thin film while moving the position of the terahertz wave irradiated on the transparent substrate or the transparent thin film, Can be measured.

1 is a view showing a configuration of an apparatus for measuring a thickness of a transparent thin film according to an embodiment of the present invention.
2 is a diagram showing a configuration of the terahertz wave detecting apparatus shown in FIG.
Fig. 3 is a diagram showing a terahertz wave before and after transmission of a measurement object in a terahertz wave detecting apparatus.
4 is a diagram schematically showing the size of a terahertz wave to be irradiated on a measurement object.
5A to 5D are SEM photographs of a transparent substrate and a transparent substrate on which a transparent thin film is formed.
6A to 6D are graphs showing the THz wave transmitted through the transparent substrate and the transmittance.
7A to 7D are graphs showing the THz wave transmitted through the transparent substrate on which the transparent thin film is formed and the transmittance.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the scope of the rights is not limited or limited by these embodiments. Like reference symbols in the drawings denote like elements.

The terms used in the following description are chosen to be generic and universal in the art to which they are related, but other terms may exist depending on the development and / or change in technology, customs, preferences of the technician, and the like. Accordingly, the terminology used in the following description should not be construed as limiting the technical thought, but should be understood in the exemplary language used to describe the embodiments.

Also, in certain cases, there may be a term chosen arbitrarily by the applicant, in which case the detailed description of the meaning will be given in the corresponding description section. Therefore, the term used in the following description should be understood based on the meaning of the term, not the name of a simple term, and the contents throughout the specification.

On the other hand, the terms first, second, etc. may be used to describe various elements, but the elements are not limited by terms. Terms are used only for the purpose of distinguishing one component from another.

It is also to be understood that when a section such as a film, a layer, an area, a configuration request, etc. is referred to as being "on" or "on" another part, And the like are included.

1 is a view showing a configuration of an apparatus for measuring a thickness of a transparent thin film according to an embodiment of the present invention. The transparent thin film thickness measuring apparatus 100 shown in FIG. 1 includes a terahertz wave detecting apparatus 110, a first thickness measuring unit 120, a second thickness measuring unit 130, a storage unit 140, an input unit 150 and a display unit 160. [

The terahertz wave detecting device 110 generates a terahertz wave to irradiate a measurement target (or sample), and detects a terahertz wave transmitted through the measurement target. The terahertz wave thus detected is used by the first thickness measuring unit 120 and / or the second thickness measuring unit 130 to measure the thickness of the measurement object.

The specific configuration and operation of the terahertz wave detecting device 110 will be described with reference to Fig. A terahertz wave (THz wave) is an electromagnetic wave corresponding to an intermediate region between an infrared ray and a microwave, and is an electromagnetic wave having a frequency of about 0.1 to 10 THz (wavelength 1 mm to 30 μm).

In addition, the terahertz wave has a very low dielectric constant for almost all materials (plastic, wood, paper, fabric, etc.

The terahertz wave detecting device 110 generates a terahertz wave using an optical rectification method and includes a laser beam generator 111, a beam splitter 112, a light retarder 113, a first ZnTe And includes a crystal 114, a first reflection mirror 115, a second reflection mirror 117, a second ZnTe crystal 118, and a detector 119.

The laser beam generator 111 generates a femtosecond laser beam having a pulse length of 50 fs, an oscillation wavelength of 800 nm, and a pulse interval of 4 s. The characteristics of such a femtosecond laser beam is merely an example, and the pulse width, the oscillation wavelength, and the pulse interval may have different values.

The beam splitter 112 separates the femtosecond laser beam into a first beam and a second beam. Here, the first beam may be a pump beam for generating a terahertz wave, and the second beam may be a probe beam for a terahertz wave measurement.

The first ZnTe crystal 114 generates a terahertz wave when the first beam is incident. More specifically, when the first beam is incident on the first ZnTe crystal 114, a transient polarization P (t) is maintained in the first ZnTe crystal 114, and the second time differential of the instant polarization Produces a terahertz wave proportional (∂ 2 P (t) / ∂t 2 ). That is, a terahertz wave is generated by a light rectification method.

The first reflection mirror 115 focuses the terahertz wave generated from the first ZnTe crystal 114 to the measurement object 116. Here, the first reflection mirror 115 may include a plurality of parabolic mirrors.

On the other hand, when the terahertz wave is transmitted through the measurement object 116, the terahertz wave is deformed. That is, as shown in FIG. 3, the pulse width and the size of the terahertz wave before and after transmission (E 0 (t)) of the measurement object 116 can be changed have.

Further, as shown in Fig. 4, the terahertz wave focused by the measurement object 116 has a size of about 300 mu m. Assuming that the measurement object 116 has a size of 1 cm x 1 cm, the thickness of the measurement object 116 may be measured as a whole using a terahertz wave, or may be measured at various points to determine the thickness uniformity of the measurement object 116 Can be measured.

The second reflection mirror 117 reflects the terahertz wave transmitted through the measurement object 116 and focuses the second THz crystal 118 onto the second ZnTe crystal 118. Here, the second reflection mirror 117 may include a plurality of parabolic mirrors.

The second ZnTe crystal 118 receives a terahertz wave transmitted through the measurement object 116 and receives a second beam through the optical retarder 113. Here, the second beam may be delayed by the optical retarder 113 and incident on the second ZnTe crystal 118 with a time difference from the terahertz wave. When a terahertz wave and a first beam are incident on the second ZnTe crystal 118, a linear electro-optic effect or a Pockels effect is generated, so that the electric field of the terahertz wave is transmitted to the second ZnTe crystal 118 Which leads to birefringence. Thereby generating a phase delay ?? of the second beam incident on the birefringent second ZnTe crystal 118. At this time, the phase delay (Δφ) is proportional to the electric field intensity of the terahertz wave (E THz), by monitoring the phase delay (Δφ) it can detect the electric field strength (E THz) in the terahertz wave. The second beam having the phase delay DELTA phi is converted to elliptically polarized light through a quarter wave plate (not shown), and two polarized components having different intensities are generated by a prism (Wallaston Prism) p-wave, and s-wave), and is incident on the detector 119.

The detector 119 may include a balanced photodiode and a detection circuit. Here, a current flows to the detection circuit by two polarized light components incident on the balanced photodiode, and the detection circuit can detect the terahertz wave using this current.

According to an embodiment of the present invention, the terahertz wave detecting apparatus 110 irradiates a terahertz wave to a transparent substrate, transmits the first terahertz wave detected by the transparent substrate to the first thickness measuring unit 120 do. Thus, when the detection of the terahertz wave on the transparent substrate is completed, a step of forming a transparent thin film on the transparent substrate can be performed.

The transparent thin film may be a polyacrylic based synthetic material, or may be formed by coating a liquid type synthetic material on a transparent substrate and UV curing the transparent thin film.

The terahertz wave detecting device 110 irradiates the transparent substrate and the transparent thin film with a terahertz wave and transmits the detected second terahertz wave transmitted through the transparent substrate and the transparent thin film to the second thickness measuring unit 130 do.

The storage unit 140 stores the first and second terahertz waves when they are detected.

The first thickness measuring unit 120 measures the first thickness of the transparent substrate using the first terahertz wave. Here, the first thickness may be measured using Equation (1) below, and the measured first thickness may be stored in the storage portion 140.

Figure 112016025630412-pat00005

In Equation 1, D 1 is a first thickness, c is a speed of light, n 1 is a refractive index of a transparent substrate, and Δf 1 is a first resonance frequency interval generated when a terahertz wave is transmitted through a transparent substrate. Here, the speed of light is 3 × 10 8 Ω, and n 1 can be changed depending on the type of the transparent substrate.

In the present invention, the transparent substrate may be formed of one of PET (poly-ethylene-terephthalate), PC (poly-carbonate) and PI (poly-imide). Also, the refractive index of PET is 2.83, the refractive index of PC is 1.54, and the refractive index of PI may be 1.89. Further,? F 1 is the resonance frequency interval of the first terahertz wave detected through the transparent substrate.

The second thickness measuring unit 130 measures the second thickness of the transparent thin film using the second THz wave and the first thickness of the transparent substrate. Here, the second thickness can be measured using the following equation (2).

Figure 112016025630412-pat00006

Here, D 2 is the second thickness, n 2 is the refractive index of the transparent film, Δf 2 is the resonant frequency interval of the second terahertz wave detected passes through the transparent substrate and the transparent thin film, n 1 is the refractive index of the transparent substrate, D 1 Is the first thickness of the transparent substrate measured through Equation (1). Further, in measuring the first thickness and the second thickness, the refractive index of the transparent substrate, the refractive index of the transparent thin film, and the speed of light may be input through the input unit 150. Here, the input unit 150 may be a keyboard, a mouse, a touch pad, a joystick, or the like.

On the other hand, the input unit 150 receives the movement control command. Here, the movement control command may be a signal for moving the irradiation and transmission position when irradiating and transmitting the terahertz wave generated through the terahertz wave detecting device 110 to the transparent substrate or the transparent thin film. Accordingly, the terahertz wave detecting device 110 outputs the first ZnTe crystal 114, the first reflecting mirror 115, the second reflecting mirror 117, and the second ZnTe crystal 118 to the x-axis , the y-axis, and the z-axis, the terahertz wave transmitted through the transparent substrate or the transparent thin film can be detected.

The first thickness measuring unit 120 can measure the first thickness of the transparent substrate according to the detection position of the first terahertz wave using the first terahertz wave that is moved in the transparent substrate and detected.

In addition, the second thickness measuring unit 130 may measure the second thickness of the transparent thin film according to the detection position of the second THz using the second THz wave transmitted through the transparent thin film.

The display unit 160 displays the first thickness measured by the first thickness measuring unit 120 or the second thickness measured by the second thickness measuring unit 130. In particular, when the first thickness or the second thickness is measured while moving the detection position of the terahertz wave on the transparent substrate or the transparent thin film, the display unit 160 displays the first or second terahertz wave at the detection position of the first terahertz wave or the second terahertz wave The first thickness or the second thickness can be displayed. Therefore, the thickness uniformity of the transparent substrate or the transparent thin film can be monitored in real time.

1, the thickness of the transparent thin film can be measured even if the transparent substrate and the transparent thin film overlap with each other with similar optical characteristics. Further, by measuring the thickness of the transparent thin film in a non-contact / non-destructive manner using a terahertz wave, it is possible to prevent thin film damage due to thickness measurement.

1, the transparent thin film thickness measuring apparatus 100 is described as including the terahertz wave detecting apparatus 110 and the thickness measuring structures 120, 130, 140 and 150 indicated by dashed lines, 120, 130, 140, 150).

That is, the transparent thin film thickness measuring apparatus 100 can separately receive data for the first and second terahertz waves detected by the terahertz wave detecting apparatus 110, Or the thickness of the transparent thin film can be measured. In this case, the transparent thin film thickness measuring apparatus 100 may be a personal computer (PC) or a computing device configured for thickness measurement.

5A to 5D are SEM photographs of a transparent substrate and a transparent substrate on which a transparent thin film is formed. Here, the transparent substrate may be a PET substrate and a PC substrate.

5A is an SEM photograph of a PET substrate, and FIG. 5B is an SEM photograph of a PC substrate. On the SEM image, the PET substrate was measured to have a thickness of 106.5 μm, and the PC substrate was measured to have a thickness of 97.3 μm.

On the other hand, FIG. 5C is a SEM photograph of a structure in which a transparent thin film (TF) is formed on a PET substrate. On the SEM photograph, the PET substrate was measured to have a thickness of 91.9 μm, the transparent thin film (TF) was measured to be 28.4 μm, and the PET substrate and the transparent thin film (TF) had a thickness of 120.3 μm.

5D is a SEM photograph of a structure having a transparent thin film (TF) formed on a PC substrate. In the SEM photograph, the PC substrate was measured to be 93.7 μm thick, the transparent thin film (TF) was measured to be 10.1 μm thick, and the PC substrate and the transparent thin film (TF) were found to be 103.8 μm thick.

6A to 6D are graphs showing the THz wave transmitted through the transparent substrate and the transmittance. Here, the transparent substrate may be a PET substrate and a PC substrate.

6A and 6B show the THz wave transmitted through the PET substrate used in FIG. 5A and the transmittance. Here, FIG. 6A is a graph showing the first terahertz wave after passing through the PET substrate (E 0 (t)) and after passing through the PET substrate (E (t)). Here, the first terahertz wave after passing through the PET substrate (E (t)) is a signal waveform obtained through the detector 119 of the terahertz wave detecting device 110 shown in FIG.

Fig. 6b, using the ratio of E 0 (t) and E (t) the Fourier transform to calculate E 0 (ω) and E (ω), respectively, and E 0 (ω) and E (ω) with respect to the frequency 1 is a graph showing the transmittance of the first THz wave. Referring to FIG. 6B, it can be seen that the resonance frequency interval? F 1 of the first terahertz is 0.5 THz. Therefore, the first thickness of the PET substrate can be measured using Equation (1).

That is, when the resonance frequency interval? F 1 of the first terahertz, the refractive index of PET (n 1 = 2.83), and the speed of light (c = 3 × 10 8 ㎧) The thickness can be measured as 106 mu m. It can be seen that this is close to the thickness (106.5 mu m) of the PET substrate measured in the SEM photograph shown in Fig. 5A.

6C and 6D show the THz wave transmitted through the PC substrate used in FIG. 5B and the transmittance. Here, FIG. 6C is a graph showing the first terahertz wave after passing through the PC substrate (E 0 (t)) and after passing through the PC substrate (E (t)).

Figure 6d is using the ratio of E 0 (t) and E (t) the Fourier transform to calculate E 0 (ω) and E (ω), respectively, and E 0 (ω) and E (ω) with respect to the frequency 1 is a graph showing the transmittance of the first THz wave. Referring to FIG. 6D, it can be seen that the resonance frequency interval? F 1 of the first terahertz is 1.0 THz. Therefore, the first thickness of the PC substrate can be measured using Equation (1).

That is, when the resonance frequency interval? F 1 of the first terahertz, the refractive index of PC (n 1 = 1.54) and the speed of light (c = 3 × 10 8 ㎧) The thickness can be measured to be 97.4 占 퐉. This is close to the thickness (97.3 mu m) of the PC substrate measured in the SEM photograph shown in Fig. 5B.

The thicknesses of the PET substrate and the PC substrate measured using the SEM photographs of FIGS. 6B and 6D, respectively, have thicknesses of the PET substrate and the PC substrate measured within the range of ± 0.5 μm, It can be seen that the accuracy is high when the thickness of the substrate is measured in a non-contact manner.

7A to 7D are graphs showing the THz wave transmitted through the transparent substrate on which the transparent thin film is formed and the transmittance. Here, the transparent substrate may be a PET substrate and a PC substrate, and a transparent thin film (TF) is formed on each of the PET substrate and the PC substrate to detect a second THz wave. For convenience of explanation, a PET substrate on which a transparent thin film (TF) is formed is denoted by "TF / PET", and a PC substrate on which a transparent thin film (TF) is formed is denoted by "TF / PC".

FIGS. 7A and 7B show the THz wave transmitted through TE / PET and the transmittance used in FIG. 5C. 7A is a graph showing a second terahertz wave after passing through TF / PET (E 0 (t)) and after passing through TF / PET (E (t)). Here, the second terahertz wave after passing through the TF / PET (E (t)) is a signal waveform obtained through the detector 119 of the terahertz wave detecting device 110 shown in FIG.

Figure 7b by using a ratio of E 0 (t) and E (t) the Fourier transform to calculate E 0 (ω) and E (ω), respectively, and E 0 (ω) and E (ω) with respect to the frequency 2 is a graph showing the transmittance of the second THz wave. Referring to FIG. 7B, it can be seen that the resonance frequency interval? F 2 of the second terahertz wave is 0.38 THz. Therefore, the second thickness of TF can be measured using Equation (2).

That is, the second resonance frequency interval of terahertz (Δf 2) and the refractive index of the PET (n 1 = 2.83), the refractive index of the TF (n 2 = 4.6), the first thickness measured in advance by the following equation 1 (91.9㎛ ) And the speed of light (c = 3 x 10 < 8 >) are applied to Equation (2), the thickness of TF can be measured to be 29.3 mu m. It can be seen that this is close to the thickness of the TF (28.4 mu m) measured in the SEM photograph shown in Fig. 5C.

On the other hand, Figs. 7C and 7D show the THz waves transmitted through TE / PC and the transmittance used in Fig. 5D. 7C is a graph showing a second terahertz wave after passing through TF / PC (E 0 (t)) and after passing through a PC substrate (E (t)).

Figure 7d is by using the ratio of E 0 (t) and E (t) the Fourier transform to calculate E 0 (ω) and E (ω), respectively, and E 0 (ω) and E (ω) with respect to the frequency 2 is a graph showing the transmittance of the second THz wave. Referring to FIG. 7D, it can be seen that the resonance frequency interval? F 2 of the second THz wave is 0.79 THz. Therefore, the second thickness of TF can be measured using Equation (2).

That is, the second resonant frequency of the terahertz wave interval (Δf 2) and the refractive index of the PC (n 1 = 1.54), the refractive index of the TF (n 2 = 4.6), the first thickness measured by the following equation 1 (93.7㎛ ) And the speed of light (c = 3 x 10 < 8 >) are applied to Equation (2), the thickness of TF can be measured to 9.9 mu m. This is close to the thickness (10.1 mu m) of the TF measured in the SEM photograph shown in Fig. 5D.

7B and 7D, the thicknesses of the TFs measured respectively by the SEM photographs shown in FIGS. 5C and 5D have an error range of ± 1.0 μm and the thickness of the TF measured respectively. It can be seen that the accuracy is high when the thickness of the TF is measured.

In addition, the thickness of the TF can be measured for a large area TF / PEC or a large area TF / PC having a size of about 30 cm x 30 cm by moving the position where the terahertz waves are irradiated and transmitted on the TF / PEC or TF / And the thickness uniformity can be monitored in real time by displaying the thickness of the TF by measuring at various points.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill 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. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

100: Transparent thin film thickness measuring device
110: terahertz wave detecting device
120: first thickness measuring section
130: second thickness measuring unit
140:
150:
160:

Claims (14)

A terahertz wave detecting device for generating a terahertz wave to detect a terahertz wave transmitted through the object to be measured;
A first thickness measuring unit that measures a first thickness of the transparent substrate using a first terahertz wave transmitted through the transparent substrate; And
A second thickness measurement unit for measuring a second thickness of the transparent thin film using the first thickness, and a second thickness measurement unit for measuring a second thickness of the transparent thin film using the first thickness,
Lt; / RTI >
Wherein the first thickness measuring unit measures a thickness of the transparent thin film for measuring the first thickness by the following equation:
[Equation 1]
Figure 112017048825863-pat00027

(Where D 1 is the first thickness, c is the speed of light, n 1 is the refractive index of the transparent substrate, and f 1 is the resonance frequency interval of the first terahertz wave detected through the transparent substrate) The method according to claim 1,
The first and second terahertz waves detected, the storage unit storing the first thickness,
The thickness of the transparent thin film. delete The method according to claim 1,
Wherein the second thickness measuring unit comprises:
An apparatus for measuring a thickness of a transparent thin film for measuring the second thickness by the following formula (2)
&Quot; (2) "
Figure 112017048825863-pat00028

(Wherein, D 2 is the second thickness, n 2 is the refractive index, Δf 2 is the resonant frequency interval, n 1 of the second terahertz wave detected by and transmitted through the transparent substrate and the transparent thin film of said transparent thin film is the Refractive index of the transparent substrate, D 1 is the first thickness) The method according to claim 1 or 4,
An input part for receiving the refractive index of the transparent substrate, the refractive index of the transparent thin film,
Wherein the thickness of the transparent thin film is measured. The method according to claim 1,
Wherein the terahertz wave detecting device comprises:
A laser beam generator for generating a femtosecond laser beam;
A beam splitter for splitting the femtosecond laser beam into a first beam and a second beam;
A first ZnTe crystal transmitting the first beam to generate a terahertz wave and transmitting the generated terahertz wave to the measurement object;
A terahertz wave transmitted through the object to be measured, and a second ZnTe crystal incident on the second beam; And
A detector for detecting an electric field intensity of a terahertz wave transmitted through the measurement object using the terahertz wave and the second beam transmitted through the second ZnTe crystal;
And the thickness of the transparent thin film. The method according to claim 6,
An input unit
Further comprising:
Wherein the terahertz wave detecting device comprises:
And the second ZnTe crystal is moved in at least one of the x-axis, the y-axis, and the z-axis according to the movement control command to detect the terahertz wave transmitted through the measurement object while the first ZnTe crystal, the reflection mirror, The thickness of the transparent thin film. 8. The method of claim 7,
Wherein the first thickness measuring unit comprises:
And measuring a first thickness of the transparent substrate according to a detection position of the first terahertz wave using the first terahertz wave that is moved and detected in the transparent substrate. 8. The method of claim 7,
Wherein the second thickness measuring unit comprises:
Wherein the second thickness of the transparent thin film is measured according to the detection position of the second terahertz wave using the second THz wave detected in the transparent thin film. 10. The method according to claim 8 or 9,
And a display unit for displaying a second thickness of the transparent thin film according to a detection position of the second terahertz wave,
Wherein the thickness of the transparent thin film is measured. The method according to claim 1,
Wherein the transparent substrate comprises:
A device for measuring the thickness of a transparent thin film made of one of PET (poly-ethylene-terephthalate), PC (poly-carbonate) and PI (poly-imide). Measuring a first thickness of the transparent substrate using a first terahertz wave transmitted through the transparent substrate; And
Measuring a second THz wave transmitted through the transparent substrate on which the transparent thin film is formed, and measuring a second thickness of the transparent thin film using the first THz wave;
Lt; / RTI >
Wherein the measuring the first thickness comprises: measuring a thickness of the transparent thin film to measure the first thickness according to the following equation:
[Equation 1]
Figure 112017048825863-pat00029

(Where D 1 is the first thickness, c is the speed of light, n 1 is the refractive index of the transparent substrate, and f 1 is the resonance frequency interval of the first terahertz wave detected through the transparent substrate) delete 13. The method of claim 12,
Wherein measuring the second thickness comprises:
A method for measuring the thickness of a transparent thin film, wherein the second thickness is measured by the following formula (2)
&Quot; (2) "
Figure 112017048825863-pat00030

(Wherein, D 2 is the second thickness, n 2 is the refractive index, Δf 2 is the resonant frequency interval, n 1 of the second terahertz wave detected by and transmitted through the transparent substrate and the transparent thin film of said transparent thin film is the Refractive index of the transparent substrate, D 1 is the first thickness)
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