WO2018182360A1 - Thickness measurement apparatus, thickness measurement method, and thickness measurement program - Google Patents

Abstract

A thickness measurement apparatus is provided. The thickness measurement apparatus may comprise: a terahertz wave signal processing unit for receiving a terahertz wave according to at least one mode among a reflection mode and a transmission mode; a refractive index information acquisition unit for acquiring refractive index information of an object, the thickness of which is to be measured, by considering second time difference information between a first reflected terahertz wave and a second reflected terahertz wave; and a thickness information acquisition unit for acquiring thickness information of the object, the thickness of which is to be measured, by considering the acquired refractive index information.

Description

Thickness measuring device, thickness measuring method and thickness measuring program

The present invention relates to a thickness measuring apparatus, a thickness measuring method and a thickness measuring program, and more particularly, a thickness measuring apparatus, a thickness measuring method and a thickness measuring the thickness of a sample using a terahertz wave that is transmitted or reflected through the sample. It is related to the measurement program.

In recent years, in order to confirm the processing and manufacturing conditions of semiconductors, flat panel displays, and micro-precision parts, high-precision measurements on the thickness, shape, and surface roughness of micro-precision parts, such as the above semiconductors, must be made.

In particular, various types of thin films are manufactured on the surface of an object in the manufacturing process of micro precision parts. Here, the thin film refers to layers having a very fine thickness formed on the surface of a base material or substrate. In general, since the thickness of the thin film has a very close influence on the performance of the product, it is necessary to accurately measure the thickness of the thin film in the manufacturing process and reflect it in the process.

In addition, in recent years, there is an increasing demand for thin film thickness measurement in a minute region of an opaque thin film composed of an opaque material in visible light as well as a previous transparent thin film. Since the shape and thickness of the micro precision parts have a very close influence on the performance of the product, there is a need to accurately measure the thickness in the manufacturing process and reflect it in the process.

To meet these needs, various thickness measuring devices and methods have been developed. For example, Korean Patent Application Publication No. 10-2013-0012419 (Application No .: 10-2011-0073614, Applicant: S & U Precision Co., Ltd.) includes a light source and light emitted from the light source focused on a thin film and reflected from the thin film side. An optical system including an objective lens for guiding light, an aperture stop for controlling an irradiation area of light guided to the objective lens, and a light guided from the optical system to adjust the thickness of the thin film. A first detector to measure and a second detector to detect image information of the thin film using light guided from the optical system, wherein the aperture is guided to the objective lens while the first detector measures the thickness of the thin film. Provided is a thin film thickness measuring device that blocks a portion and partially passes the remaining portion.

In addition, various technologies related to the thickness measuring device, the thickness measuring method, and the thickness measuring program are continuously researched and developed.

One technical problem to be solved by the present invention is to provide a thickness measuring apparatus, a thickness measuring method and a thickness measuring program for measuring the refractive index of a sample using a terahertz wave.

Another technical problem to be solved by the present invention is to provide a thickness measuring apparatus, a thickness measuring method and a thickness measuring program for measuring the thickness of a sample using a terahertz wave.

Another technical problem to be solved by the present invention is to provide a thickness measuring device, a thickness measuring method and a thickness measuring program for measuring the refractive index in a short time in the in-line process.

Another technical problem to be solved by the present invention is to provide a thickness measuring device, a thickness measuring method and a thickness measuring program to minimize the measurement error of the refractive index and thickness by the sampling rate.

Another technical problem to be solved by the present invention is to provide a thickness measuring apparatus, a thickness measuring method, and a thickness measuring program which minimizes data processing load while interpolating an error caused by a sampling rate.

The technical problem to be solved by the present invention is not limited to the above.

In order to solve the above technical problem, the present invention provides a thickness measuring device.

According to an embodiment, the thickness measuring apparatus may include a terahertz that receives a first reflected terahertz wave reflected from the back surface passing through the surface of the thickness measuring object and a second reflected terahertz wave reflected from the surface of the thickness measuring object. A wave signal processor, a refractive index information acquisition unit obtaining refractive index information of the thickness measurement object in consideration of second time difference information between the first reflected terahertz wave and the second reflected terahertz wave, and considering the refractive index information It may include a thickness information acquisition unit for obtaining the thickness information of the thickness measurement object.

According to an embodiment of the present disclosure, the refractive index information acquisition unit may include a first transmission terahertz wave that transmits the thickness measurement object in the thickness direction of the thickness measurement object, in addition to the second time difference information, and an agent obtained without transmission of the thickness measurement object. The refractive index information of the thickness measurement object may be obtained by further considering first time difference information between two transmitted terahertz waves.

According to an embodiment, the signal processor may further receive the first transmitted terahertz wave and the second transmitted terahertz wave.

According to one embodiment, the signal processor, the signal processor, the first transmission terahertz wave and the second transmission terahertz wave at a predetermined sampling rate (sampling rate), the signal processing unit, The terahertz waves distorted by the sampling rate may be interpolated among the first and second transmitted terahertz waves.

According to an embodiment of the present disclosure, the signal processor may receive the first reflected terahertz wave and the second reflected terahertz wave at a predetermined sampling rate, and the signal processor may receive the first reflected terahertz. A terahertz wave distorted by the sampling rate among the hertz wave and the second reflected terahertz wave may be interpolated.

According to an embodiment, the signal processor may selectively interpolate a specific terahertz wave in which left and right symmetry is distorted around a peak point among the terahertz waves received.

According to an embodiment of the present disclosure, the signal processing unit may include the first and second reflected terahertz waves paired with a transmission mode for repeatedly receiving a predetermined number of times of paired first and second transmitted terahertz waves. Predetermined number of times driving in the reflection mode to receive repeatedly, the predetermined number of times in the transmission mode may be more than the predetermined number of times in the reflection mode.

According to an embodiment, the refractive index information acquisition unit calculates the refractive index of the thickness measurement object.

Can be used.

According to an embodiment, the thickness information acquisition unit may calculate a thickness of the thickness measurement object.

Can be used.

In order to solve the above technical problem, the present invention provides a thickness measurement method.

According to an embodiment of the present disclosure, the thickness measuring method may include: a terrazzo receiving a first reflected terahertz wave reflected from a back surface passing through a surface of a thickness measuring object and a second reflected terahertz wave reflected from a surface of the thickness measuring object; A refractive index calculation step of obtaining refractive index information of the thickness measuring object in consideration of a Hertzian wave receiving step, second time difference information between the first and second reflecting terahertz hertz waves, and the thickness measuring object in consideration of the refractive index information It may include the thickness calculation step of obtaining the thickness information of.

According to an embodiment, in addition to the second time difference information, between the first transmitted terahertz wave transmitted through the thickness measuring object in the thickness direction of the thickness measuring object and the second transmitted terahertz wave obtained without transmitting the thickness measuring object. In consideration of first time difference information, refractive index information of the thickness measurement object may be obtained.

According to an embodiment, the terahertz wave receiving step may further include receiving the first transmitted terahertz wave and the second transmitted terahertz wave.

According to one embodiment, the terahertz wave receiving step, the step of receiving the first transmitted terahertz wave and the second transmitted terahertz wave at a predetermined sampling rate (sampling rate), and the terahertz wave receiving step The method may further include interpolating a terahertz wave distorted by the sampling rate among the first and second terahertz waves.

According to an embodiment, the terahertz wave receiving step may include receiving the first reflected terahertz wave and the second reflected terahertz wave at a predetermined sampling rate, and the terahertz wave receiving step may include: The method may further include interpolating a terahertz wave distorted by the sampling rate among the first and second reflected terahertz waves.

According to an embodiment, the terahertz wave receiving step may further include selectively interpolating a specific terahertz wave whose left and right symmetry is distorted around a peak point among the terahertz waves received. have.

According to an embodiment, the terahertz wave receiving step may include a first and a second reflecting terra pairing with a transmission mode for repeatedly receiving a predetermined number of times of pairing the first and second transmitted terahertz waves. The Hertzian wave is driven in a reflection mode which repeatedly receives a predetermined number of times, and the predetermined number of times in the transmission mode may be greater than the predetermined number of times in the reflection mode.

According to one embodiment, the step of calculating the refractive index, by calculating the refractive index of the thickness measurement object

Can be used.

According to an embodiment, the thickness calculating step may be performed by calculating a thickness of the thickness measurement object.

Can be used.

In order to solve the above technical problem, the present invention provides a thickness measurement program stored in the medium.

According to an embodiment of the present disclosure, the computer program stored in the medium may include a first reflected terahertz wave reflected from the back surface passing through the surface of the thickness measuring object and a second reflected terahertz wave reflected from the surface of the thickness measuring object. Refractive index for acquiring the refractive index information of the thickness measurement object in consideration of the terahertz wave receiving step received through the hertz wave signal processor and the second time difference information of the first and second reflected terahertz wave. And a thickness calculating step of obtaining thickness information of the thickness measuring object through a thickness information obtaining unit in consideration of the refractive index information.

According to an embodiment of the present disclosure, the calculating of the refractive index may include: a first transmission terahertz wave that transmits the thickness measurement object in the thickness direction of the thickness measurement object, in addition to the second time difference information, and the second acquired index without transmission of the thickness measurement object. The method may further include considering first time difference information between two transmission terahertz waves.

According to an embodiment, the terahertz wave receiving step may include receiving the first and second reflected terahertz waves at a predetermined sampling rate, and the terahertz wave receiving step may include receiving the received first reflection. And interpolating the terahertz waves distorted by the sampling rate among the second reflected terahertz waves.

The thickness measuring apparatus according to the embodiment of the present invention, the terahertz receiving the first reflected terahertz wave reflected from the back surface passing through the surface of the thickness measurement object and the second reflected terahertz wave reflected from the surface of the thickness measurement object A wave signal processor, a refractive index information acquisition unit obtaining refractive index information of the thickness measurement object in consideration of second time difference information between the first reflected terahertz wave and the second reflected terahertz wave, and the refractive index information in consideration of the It may include a thickness information acquisition unit for obtaining the thickness information of the thickness measurement object.

In other words, the thickness measuring apparatus according to the embodiment may acquire the refractive index of the thickness measuring object using the terahertz wave irradiated toward the thickness measuring object, and use the obtained refractive index to determine the thickness of the thickness measuring object. The thickness can be obtained. Accordingly, the thickness measuring apparatus according to the embodiment may measure both the refractive index and the thickness of the thickness measuring object (sample) within a short time.

In addition, the thickness measuring apparatus according to the embodiment may interpolate terahertz waves to be received. Thus, a more accurate refractive index and thickness can be measured than before interpolation.

In addition, the thickness measuring apparatus according to the embodiment may selectively interpolate a specific terahertz wave in which left and right symmetry is distorted around a peak point among the terahertz waves received. Accordingly, the throughput of the terahertz waves to be interpolated among the terahertz waves to be received may be reduced. As a result, the amount of data calculated in the thickness measuring apparatus according to the embodiment is reduced, so that a speed reduction phenomenon due to data overload can be prevented.

1 is a view showing a thickness measuring apparatus according to an embodiment of the present invention.

2 and 3 are views for explaining the transmission mode of the thickness measuring apparatus according to an embodiment of the present invention.

4 and 5 are diagrams illustrating a reflection mode of a thickness measuring apparatus according to an exemplary embodiment of the present invention.

6 is a graph illustrating a second reflected terahertz wave received by the second detector according to the reflection mode of the thickness measuring apparatus according to the embodiment of the present invention.

FIG. 7 is a graph illustrating an interpolation method of a second reflected terahertz wave in a thickness measurement method according to an exemplary embodiment of the present invention. FIG.

8 is a graph comparing before and after interpolation of a second reflected terahertz wave in the thickness measurement method according to an exemplary embodiment of the present invention.

9 to 12 are flowcharts illustrating a thickness measuring method according to an exemplary embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical idea of the present invention is not limited to the exemplary embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed contents are thorough and complete, and that the spirit of the present invention can be sufficiently delivered to those skilled in the art.

In the present specification, when a component is mentioned to be on another component, it means that it may be formed directly on the other component or a third component may be interposed therebetween. In addition, in the drawings, the thicknesses of shapes and sizes are exaggerated for effective explanation of technical contents.

In addition, in various embodiments of the present specification, terms such as first, second, and third are used to describe various components, but these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment. In addition, the term 'and / or' is used herein to include at least one of the components listed before and after.

In the specification, the singular encompasses the plural unless the context clearly indicates otherwise. In addition, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, element, or combination thereof described in the specification, and one or more other features or numbers, steps, configurations It should not be understood to exclude the possibility of the presence or the addition of elements or combinations thereof. In addition, the term "connection" is used herein to mean both indirectly connecting a plurality of components, and directly connecting.

In addition, in the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a view showing a thickness measuring apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the thickness measuring apparatus according to the embodiment includes a terahertz wave irradiation unit 110, a beam splitter 120, a terahertz wave signal processing unit 200, a refractive index information obtaining unit 300, And a thickness information acquisition unit 400. The thickness measuring apparatus according to the embodiment may measure the thickness d of the thickness measuring object sample by irradiating the terahertz wave to a thickness measuring object sample. According to an embodiment of the present disclosure, the thickness measurement object may be an epoxy molding compound (EMC) mold. Of course, the thickness measurement object is not limited to the EMC mold.

The terahertz wave irradiation unit 110 may irradiate the terahertz wave toward the thickness measurement object. According to an embodiment, the terahertz wave light source may be pulsed. According to another embodiment, the terahertz wave light source may be continuous.

The number of light sources of the terahertz wave may be selected according to design specifications. For example, the number of light sources of the terahertz wave may be one or two or more. According to an embodiment, the wavelength of the terahertz wave may be 3 mm to 30 μm.

According to an embodiment, the frequency of the terahertz wave may be 0.1 THz to 10 THz. As the terahertz wave has the above-described frequency range, the terahertz wave may exhibit stronger transmittance than visible or infrared rays. In addition, the terahertz wave can be used even in the presence of external light, it is possible to measure the thickness (d) of the thickness measurement object (sample) without a separate process for blocking the external light.

Terahertzpa  Signal processor 200

The terahertz wave signal processor 200 may include at least one of the first detector 210, the second detector 220, and the signal interpolator 230.

The first detector 210 may be located in a direction facing the terahertz wave irradiation unit 110 based on the thickness measurement object. The first detector 210 may receive a terahertz wave passing through the beam splitter 120 and the thickness measuring object among the terahertz waves irradiated by the terahertz wave irradiation unit 110.

The second detector 220 may be spaced apart from the terahertz wave irradiation unit 110 and the first detector 110 by a predetermined distance from the terahertz wave irradiation unit 110 at an angle of 90 °. . The second detector 220 may receive terahertz waves reflected from the surface and the back of the thickness measurement object among the terahertz waves irradiated by the terahertz wave irradiation unit 110.

The signal interpolator 230 may receive terahertz waves obtained from the first and second detectors 210 and 220 to perform predetermined signal processing. For example, the signal interpolator 230 may interpolate the terahertz waves distorted by the sampling rate among the terahertz waves received by the first and second detectors 210 and 220. . Interpolation of the terahertz wave distorted by the sampling rate will be described later.

The terahertz wave signal processor 200 may be driven in a transmission mode and a reflection mode. The transmission mode may be a method of repeatedly receiving a predetermined number of times of paired first and second transmission terahertz waves. The reflection mode may be a method of receiving a pair of first and second reflection terahertz waves repeatedly for a predetermined number of times.

Hereinafter, a transmission mode according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3, and a reflection mode according to an embodiment of the present invention will be described with reference to FIGS. 4 and 5.

Penetration mode

2 and 3 are views for explaining the transmission mode of the thickness measuring apparatus according to an embodiment of the present invention.

Referring to FIG. 2, in the transmission mode, the first detector 210 measures the thickness of the beam splitter 120 and the thickness measuring object sample among the terahertz waves irradiated by the terahertz wave irradiation unit 110. The first transmission terahertz wave P ₁ transmitted through the direction (d) may be obtained. In this case, the first detector 210 may obtain the first transmission terahertz wave P ₁ at a predetermined sampling rate.

In addition, referring to FIG. 3, in the transmission mode, the first detector 210 passes through the beam splitter 120 of the terahertz waves irradiated by the terahertz wave irradiation unit 110. The wave P ₂ can be obtained. In this case, the first detector 210 may acquire the second transmission terahertz wave P ₂ at a predetermined sampling rate.

That is, in the transmission mode, the first detector 210 transmits the first transmitted terahertz wave P ₁ and the thickness measurement object transmitted in the direction of the thickness d of the sample to be measured. The second transmission terahertz wave (P ₂ ) obtained without being able to receive.

Accordingly, in the transmission mode, the signal interpolator 230 may obtain first time difference information. The first time difference information may be a time difference between the first transmitted terahertz wave P ₁ and the second transmitted terahertz wave P ₂ measured in the transmission mode. Specifically, the first time difference information may be a time difference between a peak point of the first transmitted terahertz wave P ₁ and a peak point of the second transmitted terahertz wave P ₂ . have. In this case, the first time difference information may be an absolute value.

According to an embodiment, the first time difference information in the transmission mode may be a predetermined number of times, for example, an average value of values repeatedly obtained five times.

The transmission mode according to the exemplary embodiment of the present invention has been described above with reference to FIGS. 2 and 3. The first time difference information may be obtained by the above-described transmission mode. The first time difference information may be used to obtain refractive index information of a thickness measuring apparatus to be described later. Hereinafter, a reflection mode according to an embodiment of the present invention will be described with reference to FIGS. 4 and 5.

reflect mode

4 and 5 are diagrams illustrating a reflection mode of a thickness measuring apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 4, in the reflective mode, the second detector 220 passes through the surface t ₁ of the thickness measuring object sample among the terahertz waves irradiated by the terahertz wave irradiation unit 110. The first reflected terahertz wave R ₁ reflected from the back surface t ₂ may be obtained. In this case, the second detector 220 may acquire the first reflected terahertz wave R ₁ at a predetermined sampling rate.

In addition, referring to FIG. 5, in the reflection mode, the second detector 220 may be disposed on the surface t ₁ of the thickness measuring object sample of the terahertz waves irradiated by the terahertz wave irradiation unit 110. The reflected second reflected terahertz wave R ₂ may be obtained. In this case, the second detector 220 may acquire the second reflected terahertz wave R ₂ at a predetermined sampling rate.

That is, in the reflection mode, the second detector 220 passes through the surface t ₁ of the thickness measuring object sample and reflects the first reflected terahertz wave R ₁ reflected from the back surface t ₂ . And the second reflected terahertz wave R ₂ reflected from the surface t ₁ of the thickness measuring object sample.

Accordingly, in the reflection mode, the signal interpolator 230 may obtain second time difference information. The second time difference information may be a time difference between the first reflected terahertz wave R ₁ and the second reflected terahertz wave R ₂ measured in the reflection mode. Specifically, the second time difference information may be a time difference between a peak point of the first reflected terahertz wave R ₁ and a peak point of the second reflected terahertz wave R ₂ . have. Of course, the second time difference information may be an absolute value.

According to an embodiment, the second time difference information in the reflection mode may be a predetermined number of times, for example, an average value of values repeatedly obtained five times.

2 to 5, the time difference information acquisition in the transmission mode and the transmission mode and the time difference information acquisition in the reflection mode and the reflection mode have been described with reference to FIGS. 2 to 5. Hereinafter, the refractive index information acquisition unit 300 will be described again with reference to FIG. 1.

Refractive index  Information Acquisition (300)

Referring back to FIG. 1, the refractive index information acquisition unit 300 may determine the thickness measurement object in consideration of the first time difference information and the second time difference information acquired by the terahertz wave signal processing unit 200. refractive index information of sample) can be obtained.

The refractive index information acquisition unit 300 may use Equation 1 below to calculate the refractive index of the sample to be measured.

<Equation 1>

(n: refractive index, Δtd ₁ : time difference between first transmitted terahertz wave and second transmitted terahertz wave Δtd ₂ : time difference between first reflected terahertz wave and second reflected terahertz wave)

For reference, in order to obtain Equation 1, Equations 2 and 3 may be used.

<Equation 2>

(Δtd ₁ : time difference between the first transmitted terahertz wave and the second transmitted terahertz wave, n: refractive index, d _E : thickness of the measurement object, C: speed of light in air)

<Equation 3>

(d _E : thickness of the thickness measurement object, C: speed of light in the air, Δtd ₂ : time difference between the first reflected terahertz wave and the second reflected terahertz wave, n: refractive index)

Equation 1 may be obtained through Equation 4 below by substituting Equation 3 into Equation 2 below.

<Equation 4>

(C: speed of light in air, Δtd ₁ : time difference between first transmitted terahertz wave and second transmitted terahertz wave, Δtd ₂ : time of first reflected terahertz wave and second reflected terahertz wave Difference, n: refractive index)

Thus, the refractive index information acquisition unit 300 may obtain the refractive index information of the thickness measurement object in consideration of the first and second time difference information of the terahertz waves obtained in the transmission mode and the reflection mode. In particular, since the refractive index information obtaining unit 300 may acquire the refractive index information of the thickness measurement object in-line, the operation may be performed quickly and conveniently. The refractive index information of the thickness measurement object obtained by the refractive index information acquisition unit 300 may be used by the thickness information acquisition unit 400 to be described later to obtain thickness information of the thickness measurement object.

Thickness information Acquisition (400)

The thickness information acquisition unit 400 may obtain the thickness d information of the thickness measurement object in consideration of the refractive index information calculated by the method according to Equation 1.

The thickness information acquisition unit 400 may use Equation 5 below to calculate the refractive index of the sample to be measured.

<Equation 5>

(d _E : thickness of the thickness measurement object, C: speed of light in air, n: refractive index, Δtd ₂ : time difference between the first reflected terahertz wave and the second reflected terahertz wave)

That is, the thickness information acquisition unit 400 obtains the refractive index information in consideration of the first and second time difference information in the refractive index information acquisition unit 300 described above, and substitutes the obtained refractive index information into <Equation 5>. As a result, thickness information of the thickness measurement object may be obtained.

As described above, the thickness measuring apparatus according to the embodiment obtains a refractive index of the thickness measuring object (sample) by using a terahertz wave irradiated toward the thickness measuring object (sample), and obtains the obtained refractive index. The thickness d of the sample to be measured may be obtained using. Accordingly, the thickness measuring apparatus according to the embodiment may measure both the refractive index and the thickness of the thickness measuring object (sample) within a short time.

If the first and second time difference information is repeatedly obtained, the refractive index information obtaining unit 300 and the thickness information obtaining unit 400 utilize average values of the first and second time difference information. Of course, the refractive index and thickness information of the thickness measurement object may be acquired.

The thickness measuring apparatus according to an embodiment of the present invention has been described above. Hereinafter, the thickness measurement accuracy of the thickness measuring device according to an exemplary embodiment of the present invention will be described with reference to FIGS. 6 to 8.

6 to 8 are views for explaining the improvement of the thickness measurement accuracy of the thickness measurement apparatus according to an embodiment of the present invention. Specifically, FIG. 6 is a graph illustrating a second reflected terahertz wave received by the second detector according to the reflection mode of the thickness measuring apparatus according to the embodiment of the present invention, and FIG. 7 is a thickness measuring method according to the embodiment of the present invention. FIG. 8 is a graph illustrating an interpolation method of the second reflected terahertz wave, and FIG. 8 is a graph comparing before and after interpolation of the second reflected terahertz wave according to the embodiment of the present invention.

1 to 5 described above, the first and second transmission terahertz waves P ₁ and P ₂ and the first and second reflections received by the first and second detectors 210 and 220. The terahertz waves R ₁ and R ₂ may be distorted by various sources, for example, the sampling rate for terahertz wave signal processing and the tremors of the terahertz wave irradiator involved for terahertz wave generation.

The signal interpolator 230 may include the first and second transmission terahertz waves P ₁ and P ₂ and the first and second reflection terahertz received by the first and second detectors 210 and 220. The terahertz waves distorted by the sampling rate among the waves R ₁ and R ₂ may be interpolated. For convenience of explanation, the interpolation method will be described based on the reflected terahertz wave, but the interpolation method may be applied to the transmitted terahertz wave.

Referring to FIG. 6A, a graph in which the first and second reflected terahertz waves R ₁ and R ₂ are repeatedly received, and FIG. 6B is a A of FIG. 6A. You can see the enlarged graph. Referring to FIG. 6, the first and second reflecting Terherz waves R ₁ and R ₂ may be repeatedly received for a predetermined number of times, for example, five times. That is, as shown in FIG. 6 (b), five times of the first reflected terahertz waves R ₁ received by the second detector 220 are E _1-1 , E _2-1 , E _{3-. 1} , E _4-1 , and E _5-1 . According to an embodiment, the number of times of repetitive reception of the first and second transmission terahertz waves P ₁ and P ₂ may be less or greater than five times.

FIG. 7A is a graph illustrating a method of interpolating the first reflected terahertz wave R ₁ with _respect to B (E _5-1- ) in FIG. 6B, and FIG. 7B. ) Is a graph showing the first reflected terahertz wave R ₁ interpolated by the method described with reference to FIG. 7A.

Referring to FIG. 7A, in the case of the first reflected terahertz waves R ₁ and E _5-1 , signals are input in the order of S ₂ , S ₁ , and S _{3 according} to a sampling rate. have. In this case, the signal interpolator 230 determines that the coordinate of S ₂ is (x ₂ , y ₂ ), the coordinate of S ₁ is (x ₁ , y ₁ ), and the coordinate of S ₃ is (x ₃ , y ₃ ). can do. Here, the terahertz wave signal processor 200 is the first reflection terahertz wave (R _1, E _5-1) of peaks S ₁ of a peak-bar, which can be determined by the sampling rate S ₁ If it is recognized as the actual peak reception time and error occurs because the error accumulated in the refractive index and thickness may occur.

Therefore, in order to reduce the error due to the sampling rate, the signal interpolator 230 selects a model of a function of the first reflected terahertz waves R ₁ and E5-1 if there is no distortion due to the sampling rate. Can be. For example, the signal interpolator 230 may select y = ax ² + bx + c as a function model of the first reflected terahertz waves R ₁ and E _5-1 . The functional model is a two-dimensional function only for convenience of explanation, and of course, a different functional model may be selected.

The signal interpolator 230 may substitute the coordinates of S ₁ , S ₂ , and S _{3 into} the selected function model. In this case, the signal interpolator 230 obtains y ₁ = ax ₁ ² + bx ₁ + c by substituting the coordinates of S _{1 in} the function model, and substitutes the coordinates of S ₂ , and y ₂ = ax ₂ ² + By obtaining bx ₂ + c and obtaining the coordinates of S ₃ , y ₃ = ax ₃ ² + bx ₃ + c can be obtained.

The function in which the coordinates of S ₁ , S ₂ , and S ₃ are substituted may be summarized by Equation 6 below.

<Equation 6>

When the unknown C is obtained from Equation 6, it may be represented by C = X ⁻¹ Y.

When the peak point is obtained using C = X ⁻¹ Y and y = ax ² + bx + c, it may be represented by x _peak = -b / 2a and y _peak = f (-b / 2a). have.

Therefore, the signal interpolator 230 is a coordinate of the peak point I of the interpolated first reflected terahertz wave R ₁ , as shown in FIG. 7B, where x _peak = -b / 2a, y _peak = f (-b / 2a) can be obtained. As shown in FIG. 7B, the interpolated peak reception time point may be modified to be slightly later than S ₁ .

Thus, even if the obtained terahertz wave is distorted by the sampling rate, the signal interpolator 230 may determine a more accurate terahertz wave reception time point according to the above-described signal interpolation method.

As shown in FIG. 8, when the first reflected terahertz wave R ₁ is repeatedly received five times, interpolation may be performed on the repeatedly received first reflected terahertz waves R ₁ . . The interpolated first reflected terahertz waves (R ₁ ) are shown as E _1-2 , E _2-2 , E _3-2 , E _4-2 , and E _5-2 . As shown in FIG. 8, the peak points of the first reflected terahertz wave R ₁ before interpolation may be corrected to an accurate value by interpolation. Accordingly, when the refractive index of the thickness measurement object, which will be described later, is used, the more accurate refractive index may be obtained by using the interpolated first reflection terahertz wave R ₁ .

The method of interpolating the second reflected terahertz wave R ₂ distorted by the sampling rate described above with reference to FIGS. 6 to 8 may include the first reflected terahertz wave distorted by the sampling rate. R ₁ ), the first transmission terahertz wave (P ₁ ), and the second transmission terahertz wave (P ₂ ) can also be applied. Accordingly, more accurate refractive index and thickness may be obtained when calculating the refractive index and thickness of the thickness measuring object described later.

Furthermore, the terahertz wave signal processing unit 200 according to an embodiment of the present invention interpolates the received terahertz waves, but selects a case where the distortion degree due to the sampling rate is larger than a predetermined reference, thereby selecting the selected terahertz waves. Can be interpolated.

Referring to FIG. 7B, the signal interpolator 230 may selectively interpolate a specific terahertz wave in which left and right symmetry is distorted around a peak point among received terahertz waves. To this end, the signal interpolator 230 may consider the left and right symmetry of the terahertz wave received. More specifically, the signal interpolator 230 receives the S _2, S _1, S ₃ selected for the S ₁ that of the ball to a peak point, and, based on the S ₁ area to the left (k ₂₎ and S ₁ As a reference, the area k ₁ on the right side can be compared. In this case, when the ratio k ₁ / k ₂ is a predetermined value, for example, 90% or more, the signal interpolator 230 may not perform interpolation by determining that the distortion due to the sampling rate is not large. On the contrary, when k ₁ / k ₂ is less than 90%, it may be determined that the distortion caused by the sampling rate is large and interpolation may be performed.

Accordingly, the thickness measuring apparatus according to the embodiment can reduce the throughput of the terahertz wave to be interpolated among the terahertz waves to be received. As a result, the amount of data calculated in the thickness measuring apparatus according to the embodiment is reduced, so that a speed reduction phenomenon due to data overload can be prevented.

The error generation caused by the sampling rate and the interpolation method thereof have been described. Hereinafter, an error caused by the tremor of the terahertz wave irradiation unit and an interpolation method thereof will be described.

1 to 5, the first and second transmitted terahertz waves P ₁ and P ₂ received by the first detector 210 may have a sampling rate for terahertz wave signal processing. In addition, it may be distorted by the tremor of the terahertz wave irradiation unit 110 accompanying the generation of terahertz wave. That is, when the terahertz wave irradiation unit 110 generates a terahertz wave, a vibrator is used. Since a difference occurs in the generation time between the terahertz waves generated through the vibrator, as shown in FIG. 6 (b). Thus, the five reflection terahertz wave _{(E 1-1, E 2-1, E} 3-1, E 4-1, E and _{5- 1)} may be received are separated from each other.

In particular, the distortion caused by the tremor of the terahertz wave irradiation unit 110 may occur more in the transmission mode than in the reflection mode. In the transmissive mode, this means that the paired first transmitted terahertz waves (P ₁ ) and the second transmitted terahertz waves (P ₂ ) are distinct terahertz waves. This is because the hertzian wave R ₁ and the second reflective terahertz wave R ₂ are the same terahertz pie. Therefore, in the reflection mode, the distortion caused by the tremor of the terahertz wave irradiation unit 110 may be canceled when the second time difference information between the first and second reflection terahertz waves R ₁ and R ₂ is obtained. Because of this, the transmission mode may be more exposed to error.

Therefore, in order to interpolate the first and second transmitted terahertz waves P ₁ and P ₂ distorted by the tremor of the terahertz wave irradiation unit 110, the signal interpolators 230 are paired. The number of reception repetitions of the first and second transmission terahertz waves P ₁ and P ₂ may be increased by receiving the first and second reflection terahertz waves R ₁ and R ₂ . That is, if the terahertz wave signal processing unit 200 acquires the second time difference information with the average value by repeating the reflection mode five times, the transmission mode may obtain the first time difference information with the average value by repeating the time 10 times. have. As a result, the terahertz wave signal processor 200 may minimize an error that may occur when acquiring first time difference information.

The terahertz wave signal processor 200 may set the sampling rate in the transmission mode to be higher than the sampling rate in the reflection mode. As a result, the terahertz wave signal processor 200 may minimize an error due to a sampling rate occurring in the transmission mode. Therefore, the terahertz wave signal processing unit 200 minimizes errors by applying a high sampling rate when processing a signal in a transmission mode that is further exposed to an error generating environment, and reflects relatively less of an error generating environment. By applying a low sampling rate in the signal processing in the mode, it is possible to improve the data processing speed.

6 to 8 have been described with respect to the thickness measurement accuracy improvement configuration according to an embodiment of the present invention. Hereinafter, a thickness measuring method according to an exemplary embodiment of the present invention will be described with reference to FIGS. 9 to 12.

9 to 12 are flowcharts illustrating a thickness measuring method according to an exemplary embodiment of the present invention.

Referring to FIG. 9, in the thickness measuring method according to the embodiment, receiving a terahertz wave according to at least one of a reflection mode and a transmission mode (S110), and calculating a refractive index to obtain refractive index information of a thickness measurement object. Step S120, and a thickness calculation step S130 of obtaining thickness information of the thickness measurement object. Hereinafter, each step will be described in detail.

In operation S110, a terahertz wave according to at least one of the reflection mode and the transmission mode may be received. Reference will be made to FIG. 10 to describe step S110 in detail. In describing each step, portions overlapping with the above-described portions will be briefly described.

Step S110

Referring to FIG. 10, step S110 may include steps S210, S220, and S230 in the transmission mode according to the mode determined in step S115, and may include steps S310, S320, and S330 in the reflection mode.

When it is determined in the transmission mode in step S115 that the first transmission of the terahertz wave (P ₁ ) transmitted in the thickness direction of the thickness measurement object (S210), the second transmission received without transmitting the thickness measurement object Acquiring the terahertz wave (P ₂ ) (S220), and interpolating the distorted terahertz wave (S230) of the first and second transmission terahertz waves (P ₁ , P ₂ ) can be performed. have. As a result, the signal interpolator 230 may acquire the interpolated first and second transmission terahertz waves P ₁ and P ₂ .

Acquiring a first transmitted terahertz wave P ₁ transmitted in the thickness direction of the thickness measuring object (S210), and obtaining a second transmitted terahertz wave P ₂ received without transmitting the thickness measuring object. (S220), and interpolating the distorted terahertz waves of the first and second transmission terahertz waves (P ₁ , P ₂ ) (S230) forms a cycle, and the transmission mode cycle may be repeatedly performed a predetermined number of times. Can be. Accordingly, the accuracy of the thickness calculation step (S130) of obtaining thickness information of the thickness measurement object may be improved.

The thickness measuring method according to the embodiment may selectively interpolate the received terahertz waves in order to reduce the throughput of terahertz waves to be interpolated among the terahertz waves to be received. Reference is made to FIGS. 11 and 12 to illustrate this.

Referring to FIG. 11, the step S230 of interpolating the distorted terahertz waves of the first and second transmission terahertz waves P ₁ and P ₂ may include the first and second transmission terahertz waves P. FIG. _The method may further include determining whether the left and right symmetry meets a predetermined criterion based on the peak point of ₁ , P ₂ .

When the left and right symmetry meets a predetermined criterion, the refractive index calculation step S120 may be performed without interpolation of the first and second transmission terahertz waves P ₁ and P ₂ . When the left and right symmetry does not meet a predetermined criterion, the interpolation of the first and second transmission terahertz waves P ₁ and P ₂ is performed (S234), and the refractive index calculation step (S120) may be performed. Can be.

In order to explain the thickness measuring method in the reflection mode as well as the thickness measuring method in the above-described transmission mode, referring to FIG. 10 again, if it is determined in the reflection mode in the step S115, it passes through the surface of the thickness measurement object. Obtaining the first reflected terahertz wave R1 reflected from the rear surface (S310), obtaining the second reflected terahertz wave R2 reflected from the surface of the thickness measurement object (S320), and Interpolating the distorted terahertz waves of the first and second reflection terahertz waves R1 and R2 may be performed (S330). Accordingly, the signal interpolator 230 may obtain interpolated first and second reflected terahertz wave (R1, R2) information.

Acquiring the first reflected terahertz wave R ₁ reflected from the rear surface through the surface of the thickness measuring object (S310), and the second reflected terahertz wave R reflected from the surface of the thickness measuring object (R ₁ ). ₂ ) acquiring (S320) and interpolating the distorted terahertz waves of the first and second reflected terahertz waves (R ₁ , R ₂ ) (S330) form a cycle, and the cycle of the reflection mode. May be repeated a predetermined number of times. Accordingly, the accuracy of the thickness calculation step (S130) of obtaining thickness information of the thickness measurement object may be improved.

Referring to FIG. 12, interpolating the distorted terahertz waves of the first and second reflective terahertz waves R ₁ and R ₂ (S330) may include the first and second reflected terahertz waves R. _The method may further include determining whether the left and right symmetry meets a predetermined criterion based on the peak points of ₁ and R ₂ .

When the left and right symmetry meets a predetermined criterion, the refractive index calculation step S120 may be performed without interpolation of the first and second reflected terahertz waves R ₁ and R ₂ . If the left and right symmetry does not meet a predetermined criterion, after performing the step of interpolating the first and second reflected terahertz waves R ₁ and R ₂ (S334), the refractive index calculation step (S120) may be performed. Can be.

According to an embodiment, the number of repetitions of the transmission mode including the steps S210 and S220 may be greater than the number of repetitions of the reflection mode including the steps S310 and S320. Accordingly, the error of the transmission mode that is relatively exposed to the error rather than the reflection mode can be minimized.

Thus, in step S110, a terahertz wave according to at least one of the reflection mode and the transmission mode may be received.

Step S120

The refractive index calculation step using the first and second transmission terahertz waves (P ₁ , P ₂ ) and the first and second reflection terahertz waves (R ₁ , R ₂ ) obtained in step S110 described above ( S120) may be performed. Referring back to FIG. 10, the refractive index calculation step S120 may use Equation 1 as described above to calculate the refractive index of the thickness measurement object based on the terahertz wave information obtained in step S110. have. Accordingly, refractive index information of the thickness measurement object may be obtained.

<Equation 1>

(n: refractive index, Δtd ₁ : time difference between first transmitted terahertz wave and second transmitted terahertz wave Δtd ₂ : time difference between first reflected terahertz wave and second reflected terahertz wave)

Step S130

The thickness calculating step S130 may be performed in consideration of the refractive index obtained in the refractive index calculating step S120. Equation 5 described above may be used as an expression for calculating the thickness of the thickness measurement object. Accordingly, thickness information of the thickness measurement object may be obtained.

<Equation 5>

(d _E : thickness of the thickness measurement object, C: speed of light in air, n: refractive index, Δtd ₂ : time difference between the first reflected terahertz wave and the second reflected terahertz wave)

The calculation process performed in the refractive index calculation step S120 and the thickness calculation step S130 may correspond to a process performed by the refractive index information obtaining unit and the thickness information obtaining unit described with reference to FIGS. 1 to 8. .

The above-described thickness measuring method may be provided to a thickness measuring program stored in the medium to implement the thickness measuring method. Hereinafter, a thickness measuring program in which the thickness measuring method is stored in a medium will be described.

The thickness measuring program stored in the medium of the thickness measuring method according to the embodiment includes a first reflecting terahertz wave reflected from the back surface passing through the surface of the thickness measuring object and a second reflecting terahertz reflected from the surface of the thickness measuring object. A terahertz wave receiving step of receiving a wave through the terahertz wave signal processor, and considering the second time difference information of the first and second reflected terahertz waves, the refractive index information of the thickness measurement object is obtained through the refractive index information acquisition unit. And a thickness calculating step of obtaining thickness information of the thickness measuring object through the thickness information obtaining unit in consideration of the refractive index obtaining step and the refractive index information.

The refractive index calculating step may include the first transmission terahertz wave of the thickness measurement object transmitted in the thickness direction of the thickness measurement object and the second transmission terahertz wave obtained without transmission of the thickness measurement object, in addition to the second time difference information. The first time difference information may be further considered, and may be stored in a medium for obtaining refractive index information of the thickness measurement object.

The terahertz wave receiving step may be stored in a medium for receiving terahertz waves at a predetermined sampling rate. In addition, the terahertz wave receiving step may be stored in a medium for interpolating terahertz waves distorted by the sampling rate among the received terahertz waves.

At this time, each step of the thickness measurement method according to an embodiment of the present invention may be performed by a single processor, or may be performed by a plurality of processors.

Hereinafter, specific experimental results of the thickness measurement interpolation according to the embodiment will be described.

Experimental Example 1

For the EMC 0.30T, the time delay (ps) of the transmission mode and the reflection mode was measured by using the thickness measuring apparatus according to the embodiment, and the refractive index was obtained. In order to improve the consistency of the refractive index, repeated measurements were performed five times, and interpolation was performed for each repetition. The results for Experimental Example 1 are summarized through Table 1 below.

	1 time	Episode 2	3rd time	4 times	5 times	Average
Transmission Mode (Interpolation X)	0.8838	0.8838	0.8838	0.8838	0.8838	0.8838
Transmission Mode (Interpolation O)	0.9015	0.9029	0.9013	0.9041	0.9002	0.9020
Reflection Mode (Interpolation X)	3.7562	3.7010	3.7010	3.7562	3.7010	3.7230
Reflection Mode (Interpolation O)	3.7125	3.7139	3.7135	3.7356	3.7141	3.7179

When the interpolation was not performed based on the average value shown in Table 1, the refractive index of the EMC 0.30T was found to be 1.9040, and when interpolating, the refractive index of the EMC 0.30T was found to be 1.9426.

Experimental Example 2

For the EMC 0.45T, the time delay (ps) of the transmission mode and the reflection mode was measured using the thickness measuring apparatus according to the embodiment, and the refractive index was obtained. In order to improve the consistency of the refractive index, repeated measurements were performed five times, and interpolation was performed for each repetition. The results for Experimental Example 2 are summarized through Table 2 below.

	1 time	Episode 2	3rd time	4 times	5 times	Average
Transmission Mode (Interpolation X)	1.3257	1.3257	1.3809	1.3257	1.3257	1.3368
Transmission Mode (Interpolation O)	1.356	1.3738	1.3786	1.3737	1.3727	1.3749
Reflection Mode (Interpolation X)	5.6895	5.6895	5.6895	5.6895	5.6895	5.6895
Reflection Mode (Interpolation O)	5.6945	5.6701	5.6720	5.7043	5.6703	5.6822

When the interpolation was not performed based on the average value shown in Table 2, the refractive index of the EMC 0.45T was found to be 1.8864, and when interpolating, the refractive index of the EMC 0.45T was found to be 1.9377.

The refractive indices before and after interpolation confirmed through Experimental Example 1 and Experimental Example 2 may be summarized in Table 3 below.

	Refractive index
0.30T (interpolation X)	1.9040
0.30T (interpolated O)	1.9426
0.45T (interpolation X)	1.8864
0.45T (0 interpolation)	1.9377

As can be seen from Table 1 and Table 2, when interpolation was performed in the transmission mode and reflection mode, it was confirmed that a change in time delay occurred compared with the case where no interpolation was performed. Accordingly, as can be seen in Table 3, when the refractive index before interpolation and the refractive index after interpolation are compared, an error of about 3.7% is generated. In other words, when measuring the refractive index of the EMC mold, it can be seen that performing interpolation can obtain a more accurate refractive index.

Experimental Example 3

The thickness of EMC 0.30T was calculated from the pre-interpolation index and the interpolation refractive index obtained in Experimental Example 1, and the thickness obtained from the terahertz wave was compared with the actual thickness. The actual thickness of EMC 0.30T was measured by X-section. In addition, for a more accurate comparison of the actual thickness obtained with the terahertz wave of the EMC 0.30T, 5 arbitrary points on the left side, 5 arbitrary points on the center, and 5 arbitrary points on the right side The place was taken out and the thickness of each was compared. The results for Experimental Example 3 are summarized in Table 4 below.

Point	Location		Refractive Index (Interpolation x) = 1.9039		Refractive Index (interpolation o) = 1.9426
		Actual thickness (um)	Terahertz wave thickness (interpolation, um)	Error (um)	Terahertz wave thickness (interpolated o, um)	Error (um)
One	Left	292.6	295.72	3.12	289.30	3.30
2		292.6	297.46	4.86	291.08	1.52
3		290.2	294.85	4.65	289.02	1.18
4		290.2	296.59	6.39	290.51	0.31
5		291.4	296.59	5.19	291.41	0.01
One	Center	286.7	293.11	6.41	287.01	0.31
2		288.5	296.59	8.09	290.31	1.81
3		287.3	291.37	4.07	285.10	2.20
4		287.3	295.72	8.42	289.93	2.63
5		286.7	294.85	8.15	289.52	2.82
One	Right	283.8	286.15	2.35	281.77	2.03
2		288.5	290.5	2	285.82	2.68
3		289.1	292.24	3.14	285.75	3.35
4		286.2	292.24	6.04	286.86	0.66
5		287.9	295.72	7.82	289.11	1.21

The average of the measured values in <Table 4> is summarized through <Table 5> below.

Point	Location		Refractive Index (Interpolation x) = 1.9039		Refractive Index (interpolation o) = 1.9426
		Actual thickness (um)	Terahertz wave thickness (interpolation, um)	Error (um)	Terahertz wave thickness (interpolated o, um)	Error (um)
Average	Left	291.4	296.24	4.84	290.26	1.26
	Center	287.3	264.33	7.03	288.37	1.95
	Right	287.1	291.37	4.27	285.86	1.99
	Total	288.6	293.98	5.38	288.17	1.73

Experimental Example 4

The thickness of EMC 0.45T was calculated from the pre-interpolation index and the interpolation refractive index obtained in Experimental Example 2, and the thickness obtained from the terahertz wave was compared with the actual thickness. The actual thickness of EMC 0.45T was measured by X-section. In addition, for a more accurate comparison of the actual thickness obtained with the terahertz wave of the EMC 0.45T, five random points on the left, five random points on the center, and five random points on the right The place was taken out and the thickness of each was compared. The results for Experimental Example 4 are summarized through Table 6 below.

Point	Location		Refractive Index (Interpolation x) = 1.8864		Refractive Index (interpolation o) = 1.9377
		Actual thickness (um)	Terahertz wave thickness (interpolation, um)	Error (um)	Terahertz wave thickness (interpolated o, um)	Error (um)
One	Left	443.9	452.96	9.06	441.93	1.97
2		445.9	457.36	11.46	445.92	0.02
3		442	454.72	12.72	443.75	1.75
4		449.7	459.99	10.29	447.16	2.54
5		448.8	458.23	9.43	445.82	2.98
One	Center	441	453.84	12.84	441.49	0.49
2		445.9	457.35	11.45	444.91	0.99
3		443.9	452.96	9.06	440.72	3.18
4		443.9	458.23	14.33	445.94	2.04
5		443.9	455.6	10.7	444.82	0.08
One	Right	-	-	-	-	-
2		443.9	452.96	9.06	440.35	3.55
3		442.9	450.33	7.43	440.28	2.62
4		442.9	458.23	15.33	445.31	2.41
5		446.8	454.72	7.92	442.16	4.64

The average of the measured values in <Table 6> is summarized through <Table 7> below.

Point	Location		Refractive Index (Interpolation x) = 1.9039		Refractive Index (interpolation o) = 1.9426
		Actual thickness (um)	Terahertz wave thickness (interpolation, um)	Error (um)	Terahertz wave thickness (interpolated o, um)	Error (um)
Average	Left	446.1	456.65	10.59	444.91	1.85
	Center	443.9	455.60	11.68	443.57	1.36
	Right	444.1	454.06	9.94	442.03	3.30
	Total	444.7	455.53	10.79	443.61	2.09

As can be seen from <Table 5> and <Table 7>, in Example 3, the error of total average thickness before interpolation of EMC 0.30T was 5.38 um, but the error of total average thickness after interpolation was reduced to 1.73 um. . In addition, in Example 4, the error of the total mean thickness before interpolation of EMC 0.45T was 10.79 um, but the error of the total mean thickness after interpolation was reduced to 2.09.

Thus, when measuring the thickness of the EMC mold, it can be seen that performing the interpolation can obtain a more accurate thickness. In addition, when measuring the thickness of the EMC mold using the thickness measuring apparatus according to an embodiment of the present invention, it can be seen that the difference between the actual thickness of the EMC mold is very small.

According to one embodiment of the present invention, the refractive index information of the thickness measurement object may be obtained, and the thickness information may be obtained based on the obtained refractive index information. In other words, since refractive index information and thickness information can be obtained together, ease of use can be improved. In particular, when the thickness measuring object is an EMC mold, the refractive index of the EMC mold may vary depending on the ratio of the composition. In other words, there is a need to measure the refractive index of the EMC mold at that time. In this regard, according to one embodiment of the present invention, since the refractive index and the thickness can be measured together in the inline, a separate refractive index measurement step can be omitted, thereby improving convenience of use.

Furthermore, according to an embodiment of the present invention, since the error accompanying the sampling rate can be minimized, the accuracy of the thickness measurement can be improved. In addition, two performance indicators of error reduction and data processing efficiency may be achieved by dividing the reflection mode and the transmission mode by inputting resources for error reduction in a transmission mode in which an error occurrence is relatively high.

As mentioned above, although this invention was demonstrated in detail using the preferable embodiment, the scope of the present invention is not limited to a specific embodiment, Comprising: It should be interpreted by the attached Claim. In addition, those skilled in the art should understand that many modifications and variations are possible without departing from the scope of the present invention.

The thickness measuring apparatus, the thickness measuring method, and the thickness measuring program according to the exemplary embodiment of the present invention may be used where a thickness measurement of a micro precision component such as a semiconductor is required.

Claims (20)

1. A terahertz wave signal processor configured to receive a first reflected terahertz wave reflected from the back surface through the surface of the thickness measuring object and a second reflected terahertz wave reflected from the surface of the thickness measuring object;

   A refractive index information acquisition unit obtaining refractive index information of the thickness measurement object in consideration of second time difference information between the first reflected terahertz wave and the second reflected terahertz wave; And

   And a thickness information acquisition unit configured to obtain thickness information of the thickness measurement object in consideration of the refractive index information.
2. According to claim 1,

   The refractive index information obtaining unit may, in addition to the second time difference information, between the first transmitted terahertz wave transmitted through the thickness measuring object in the thickness direction of the thickness measuring object and the second transmitted terahertz wave obtained without transmitting the thickness measuring object. The thickness measuring apparatus may further acquire refractive index information of the thickness measuring object by further considering first time difference information.
3. The method of claim 2,

   And the signal processing unit further receives the first transmitted terahertz wave and the second transmitted terahertz wave.
4. The method of claim 3, wherein

   The signal processor is configured to receive the first transmitted terahertz wave and the second transmitted terahertz wave at a predetermined sampling rate,

   And the signal processing unit interpolates a terahertz wave distorted by the sampling rate among the first and second terahertz waves.
5. According to claim 1,

   The signal processing unit receives the first reflected terahertz wave and the second reflected terahertz wave at a predetermined sampling rate,

   And the signal processing unit interpolates a terahertz wave distorted by the sampling rate among the first and second reflected terahertz waves.
6. The method according to claim 4 or 5,

   The signal processor is a thickness measuring device for selectively interpolating a specific terahertz wave of symmetrical symmetry distorted around a peak point of the terahertz waves to be received.
7. The method of claim 3, wherein

   The signal processor is configured to receive the first and second reflected terahertz waves paired with a transmission mode for repeatedly receiving a predetermined number of times of paired first and second transmitted terahertz waves in a predetermined number of times. Drive in reflective mode,

   And the predetermined number of times in the transmission mode is greater than the predetermined number of times in the reflection mode.
8. The method of claim 2,

   The refractive index information acquisition unit calculates the refractive index of the thickness measurement object.

   

   Thickness measuring apparatus using the.

   (n: refractive index, Δtd ₁ : time difference between first transmitted terahertz wave and second transmitted terahertz wave Δtd ₂ : time difference between first reflected terahertz wave and second reflected terahertz wave)
9. The method of claim 8,

   The thickness information acquisition unit may calculate a thickness of the thickness measurement object.

   

   Thickness measuring apparatus using the.

   (d _E : thickness of the thickness measurement object, C: speed of light in air)
10. A terahertz wave receiving step of receiving a first reflected terahertz wave reflected from the back surface through the surface of the thickness measuring object and a second reflected terahertz wave reflected from the surface of the thickness measuring object;

    A refractive index calculation step of obtaining refractive index information of the thickness measurement object in consideration of second time difference information between the first and second reflective terahertz waves; And

    And a thickness calculation step of obtaining thickness information of the thickness measurement object in consideration of the refractive index information.
11. The method of claim 10,

    The refractive index calculation step may include, in addition to the second time difference information, between the first transmitted terahertz wave transmitted through the thickness measuring object in the thickness direction of the thickness measuring object and the second transmitted terahertz wave obtained without transmitting the thickness measuring object. The thickness measuring method of acquiring refractive index information of the thickness measuring object by further considering first time difference information.
12. The method of claim 11, wherein

    The terahertz wave receiving step may further include receiving the first transmitted terahertz wave and the second transmitted terahertz wave.
13. The method of claim 11, wherein

    The terahertz wave receiving step may include receiving the first transmitted terahertz wave and the second transmitted terahertz wave at a predetermined sampling rate, and

    The terahertz wave receiving step may further include interpolating a terahertz wave distorted by the sampling rate among the first and second transmitted terahertz waves.
14. The method of claim 10,

    The terahertz wave receiving step may include receiving the first reflected terahertz wave and the second reflected terahertz wave at a predetermined sampling rate, and

    The terahertz wave receiving step may further include interpolating a terahertz wave distorted by the sampling rate among the first and second reflected terahertz waves.
15. The method according to claim 13 or 14,

    The terahertz wave receiving step may further include selectively interpolating a specific terahertz wave whose symmetry is distorted about a peak point among the terahertz waves received.
16. The method of claim 11, wherein

    In the terahertz wave receiving step, a predetermined number of first and second reflected terahertz waves paired with a transmission mode for repeatedly receiving a predetermined number of times of paired first and second transmission terahertz waves are predetermined. Driving in repetitive mode of receiving repeatedly,

    And the predetermined number of times in the transmission mode is greater than the predetermined number of times in the reflection mode.
17. The method of claim 11, wherein

    The refractive index calculation step is to calculate the refractive index of the thickness measurement object

    

    Thickness measurement method using the.

    (n: refractive index, Δtd ₁ : time difference between first transmitted terahertz wave and second transmitted terahertz wave Δtd ₂ : time difference between first reflected terahertz wave and second reflected terahertz wave)
18. The method of claim 17,

    In the thickness calculating step, the thickness of the thickness measuring object is calculated.

    

    Thickness measurement method using the.

    (d _E : thickness of the thickness measurement object, C: speed of light in air)
19. A terahertz wave receiving step of receiving a first reflected terahertz wave reflected from the back surface through the surface of the thickness measuring object and a second reflected terahertz wave reflected from the surface of the thickness measuring object through a terahertz wave signal processor;

    A refractive index calculation step of obtaining refractive index information of the thickness measurement object through a refractive index information acquisition unit in consideration of second time difference information between the first and second reflective terahertz waves; And

    And a thickness measuring program stored in a medium for executing a thickness calculating step of obtaining thickness information of the thickness measuring object through a thickness information obtaining unit in consideration of the refractive index information.
20. The method of claim 19,

    The refractive index calculation step may include, in addition to the second time difference information, between the first transmitted terahertz wave transmitted through the thickness measuring object in the thickness direction of the thickness measuring object and the second transmitted terahertz wave obtained without transmitting the thickness measuring object. And further considering the first time difference information.

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