DEVICE AND METHOD FOR THICKNESS MEASUREMENT

Abstract

A thickness measuring device is provided. The thickness measuring device measures the thickness of a second layer in a sample containing a first layer and the second layer stacked on top of the first layer to expose an edge of the first layer. The thickness measuring device may include: a terahertz wave transmitter that emits terahertz waves toward an edge of the second layer, so that the first and second layers are simultaneously irradiated directly with the terahertz waves by single irradiation; a terahertz wave detector that, with respect to a reflected location of the terahertz waves, detects a first terahertz wave (R1) reflected from a surface of the second layer, a second terahertz wave (R2) reflected from an exposed surface of the first layer, and a third terahertz wave (R3) reflected from an interface between the first and second layers;and a computer that calculates a refractive index of the second layer based on a detection time difference (Δt1) between a detection time of the first terahertz wave (R1) and a detection time of the second terahertz wave (R2) and a detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and a detection time of the third terahertz wave (R3), and calculates the thickness of the second layer based on the calculated refractive index of the second layer.

Description

Thickness measuring device and method

[0001] The present invention relates to a thickness measurement device and method, and more specifically, to a thickness measurement device and method capable of obtaining reliable thickness information on a thickness measurement target through a reflection mode of terahertz waves.

[0002] As cutting-edge industries such as the semiconductor and display industries develop, high-density and miniaturization technologies are gaining attention, and the development of non-destructive inspection technologies is also in demand.

[0003] In particular, in the semiconductor and display industries, specimens of various thicknesses and shapes are manufactured for use in micro-precision components. Because these specimens significantly impact product performance, it is essential to manufacture them with uniform thickness. Therefore, precise thickness measurement is essential during the manufacturing process for these baby specimens.

[0004] Meanwhile, terahertz waves have excellent penetration properties into non-conductive materials except metals, and are harmless to the human body due to their lower energy than X-rays. Due to these characteristics, terahertz waves can be applied to non-destructive inspection technologies.

[0005] Additionally, in the specimen manufacturing process, the specimen may be composed of multilayer thin films. In the case of a specimen composed of multilayer thin films, it may be difficult to measure the thickness of each layer separately during the manufacturing process. Therefore, when the specimen is composed of multilayer thin films, there is a need to measure the thickness of each thin film layer constituting the specimen without separating the specimen into individual thin films.

[0006] Meanwhile, the refractive index of each multilayer thin film was previously measured using transmission mode. However, when a multilayer thin film is composed of a laminate of metal and non-metal, light is reflected by the metal, making it difficult to obtain accurate information on the refractive index of the thin film, which serves as the basis for calculating the thickness of the thin film, using transmission mode.

[0007] The technical problem to be solved by the present invention is to provide a thickness measurement device and method that can obtain reliable thickness information on a thickness measurement target through the reflection mode of terahertz waves.

[0008] The technical problems to be solved by the present invention are not limited to those described above.

[0009] To solve the above technical problem, the present invention provides a thickness measuring device.

[0010] According to one embodiment, the thickness measuring device is a thickness measuring device for measuring a thickness of a second layer in a specimen including a first layer and a second layer laminated on the first layer in a form in which an edge of the first layer is exposed upward, the thickness measuring device comprising: a terahertz wave irradiation unit that irradiates terahertz waves toward an edge of the second layer so that the terahertz waves are directly irradiated simultaneously to the first layer and the second layer through a single irradiation; a terahertz wave detection unit that detects, based on a position at which the irradiated terahertz waves are reflected, a first terahertz wave (R1) reflected from a surface of the second layer, a second terahertz wave (R2) reflected from an exposed surface of the first layer, and a third terahertz wave (R3) reflected from an interface formed by the first layer and the second layer; And it may include a calculation unit that calculates the refractive index of the second layer based on the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) and the detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and the detection time of the third terahertz wave (R3), and calculates the thickness of the second layer based on the calculated refractive index of the second layer.

[0011] According to one embodiment, the operation unit calculates the refractive index (n) of the second layer through the following equation 6. s ) can be produced.

[0012]

[0013] [Formula 6]

[0014]

[0015]

[0016] Here, the above n air is the refractive index of air.

[0017] According to one embodiment, the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) is defined by Equation 1 below, the detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and the detection time of the third terahertz wave (R3) is defined by Equation 3 below, Equation 1 is summarized as Equation 2 below, Equation 3 is summarized as Equation 4 below, Equations 2 and 3 are summarized as Equation 5 below, and Equation 5 is summarized as Equation 6 above, and the calculation unit can calculate the thickness of the second layer through Equation 2 or Equation 4.

[0018]

[0019] [Formula 1]

[0020]

[0021]

[0022] [Formula 2]

[0023]

[0024]

[0025] [Formula 3]

[0026]

[0027]

[0028] [Formula 4]

[0029]

[0030]

[0031] [Formula 5]

[0032]

[0033]

[0034] Here, C is the speed of light, and d1 and d2 are the thicknesses of the second layer.

[0035] According to one embodiment, the terahertz wave detection unit detects terahertz waves reflected at each of M (a positive integer greater than or equal to 1) × N (a positive integer greater than or equal to 1) points set on the surface of the second layer, and the calculation unit can calculate the thickness of each point through the following equation 7.

[0036]

[0037] [Formula 7]

[0038]

[0039]

[0040] According to one embodiment, when the terahertz wave irradiation unit irradiates the terahertz wave at an incident angle (θ) greater than 0° and less than 90° toward the edge of the second layer, the calculation unit can calculate the thickness of the second layer through Equation 8 below converted from Equation 1, Equation 9 below converted from Equation 2, Equation 10 below converted from Equation 3, Equation 11 below converted from Equation 4, and Equation 12 below converted from Equation 5.

[0041]

[0042] [Formula 8]

[0043]

[0044]

[0045] [Formula 9]

[0046]

[0047]

[0048] [Formula 10]

[0049]

[0050]

[0051] [Formula 11]

[0052]

[0053]

[0054] [Formula 12]

[0055]

[0056]

[0057] According to another embodiment, a thickness measuring device is a thickness measuring device for measuring a thickness of a second layer in a specimen including a first layer and a second layer laminated on the first layer, the thickness measuring device comprising: a terahertz wave irradiation unit for irradiating two terahertz waves (I1, I2) with different incident angles to the second layer toward the second layer; and two first terahertz waves (R) reflected from a surface of the second layer based on a position at which the two irradiated terahertz waves (I1, I2) are reflected. 1S , R 2S ) and two second terahertz waves (R) reflected at the interface formed by the first layer and the second layer. 1T , R 2T ) detecting a terahertz wave; and two first terahertz waves (R) reflected from the surface of the second layer. 1S , R 2S ) of the first terahertz wave ((R 1S ) and the detection time of the two second terahertz waves (R) reflected from the interface formed by the first and second layers. 1T , R 2T ) of the second terahertz wave (R 1T ) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer, the difference in detection time (Δt1) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer. 1S , R 2S ) of the other first terahertz wave ((R 2S ) and the detection time of the two second terahertz waves (R) reflected from the interface formed by the first and second layers. 1T , R 2T ) of the other second terahertz wave (R 2T) and the incident angles (θ1, θ2) of the two terahertz waves (I1, I2) investigated above, the refractive index of the second layer can be calculated, and the thickness of the second layer can be calculated based on the calculated refractive index of the second layer.

[0058] According to another embodiment, the operation unit calculates the refractive index (n) of the second layer through the following equation 17. s ) can be produced.

[0059]

[0060] [Formula 17]

[0061]

[0062]

[0063] Here, the above n air is the refractive index of air, C is the speed of light, θ1 is an angle of incidence of one of the two terahertz waves (I1, I2) investigated to the second layer, θ2 is an angle of incidence of the other of the two terahertz waves (I1, I2) investigated to the second layer, and d1 and d2 are thicknesses of the second layer.

[0064] According to another embodiment, the above formula 17 can be derived through the following formulas 13 to 16.

[0065]

[0066] [Formula 13]

[0067]

[0068]

[0069] [Formula 14]

[0070]

[0071]

[0072] [Formula 15]

[0073]

[0074]

[0075] [Formula 16]

[0076]

[0077]

[0078] Here, l1 is a distance along which one of the two terahertz waves (I1, I2) investigated is propagated within the second layer, l2 is a distance along which the other of the two terahertz waves (I1, I2) investigated is propagated within the second layer, and n1 and n2 are refractive indices of the second layer.

[0079] According to another embodiment, a thickness measuring device is a thickness measuring device for measuring a thickness of a second layer in a specimen including a first layer and a second layer laminated on the first layer, the thickness measuring device comprising: a terahertz wave irradiation unit that irradiates a terahertz wave toward the second layer; a terahertz wave detection unit that detects, based on a position at which the irradiated terahertz wave is reflected, a first terahertz wave (R1) reflected from a surface of the second layer, a second terahertz wave (R2) reflected from an interface formed by the first layer and the second layer, and a third terahertz wave (R3) reflected once more within the second layer; And it may include a calculation unit that calculates the refractive index of the second layer based on the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) and the signal intensities (I1, I2, I3) of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), and calculates the thickness of the second layer based on the calculated refractive index of the second layer.

[0080] According to another embodiment, the operation unit calculates the refractive index (n) of the second layer through the following equation 32. s) can be calculated, and the thickness (d) of the second layer can be calculated through the following equation 33.

[0081]

[0082] [Formula 32]

[0083]

[0084]

[0085] [Formula 33]

[0086]

[0087]

[0088] According to another embodiment, when the terahertz wave irradiation unit irradiates the terahertz wave toward the second layer at an incident angle (θ) greater than 0° and less than 90°, the calculation unit can calculate the thickness (d) of the second layer through the following equation 37 converted from the equation 33.

[0089]

[0090] [Formula 37]

[0091]

[0092]

[0093] Meanwhile, the present invention provides a thickness measurement method.

[0094] According to one embodiment, the thickness measurement method comprises the steps of: irradiating a terahertz wave toward an edge of a second layer so that the terahertz wave is directly irradiated simultaneously to the first layer and the second layer through a single irradiation on a specimen including a first layer and a second layer laminated on the first layer in a form in which an edge of the first layer is exposed upward; detecting, based on a position at which the irradiated terahertz wave is reflected, a first terahertz wave (R1) reflected from a surface of the second layer, a second terahertz wave (R2) reflected from an exposed surface of the first layer, and a third terahertz wave (R3) reflected from an interface formed by the first layer and the second layer; And it may include a step of calculating the refractive index of the second layer based on the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) and the detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and the detection time of the third terahertz wave (R3), and calculating the thickness of the second layer based on the calculated refractive index of the second layer.

[0095] According to another embodiment, a thickness measurement method comprises the steps of: irradiating two terahertz waves (I1, I2) having different incident angles with respect to the second layer toward a specimen including a first layer and a second layer laminated on the first layer; and, based on a position at which the two irradiated terahertz waves (I1, I2) are reflected, measuring two first terahertz waves (R) reflected from a surface of the second layer. 1S , R 2S ) and two second terahertz waves (R) reflected at the interface formed by the first layer and the second layer. 1T , R 2T ) detecting step; and two first terahertz waves (R) reflected from the surface of the second layer 1S , R 2S) of the first terahertz wave ((R 1S ) and the detection time of the two second terahertz waves (R) reflected from the interface formed by the first and second layers. 1T , R 2T ) of the second terahertz wave (R 1T ) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer, the difference in detection time (Δt1) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer. 1S , R 2S ) of the other first terahertz wave ((R 2S ) and the detection time of the two second terahertz waves (R) reflected from the interface formed by the first and second layers. 1T , R 2T ) of the other second terahertz wave (R 2T ) and the incident angles (θ1, θ2) of the two terahertz waves (I1, I2) investigated above, and may include a step of calculating the refractive index of the second layer, and calculating the thickness of the second layer based on the calculated refractive index of the second layer.

[0096] According to another embodiment, for a specimen including a first layer and a second layer laminated on the first layer, the method includes: irradiating a terahertz wave toward the second layer; detecting, based on a position at which the irradiated terahertz wave is reflected, a first terahertz wave (R1) reflected from a surface of the second layer, a second terahertz wave (R2) reflected from an interface formed by the first layer and the second layer, and a third terahertz wave (R3) reflected once more within the second layer; And it may include a step of calculating the refractive index of the second layer based on the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) and the signal intensities (I1, I2, I3) of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), and calculating the thickness of the second layer based on the calculated refractive index of the second layer.

[0097] According to an embodiment of the present invention, there is provided a thickness measuring device for measuring a thickness of a second layer in a specimen including a first layer and a second layer laminated on the first layer in a form in which an edge of the first layer is exposed upward, the thickness measuring device comprising: a terahertz wave irradiation unit that irradiates terahertz waves toward an edge of the second layer so that the terahertz waves are directly irradiated simultaneously to the first layer and the second layer through a single irradiation; a terahertz wave detection unit that detects, based on a position at which the irradiated terahertz waves are reflected, a first terahertz wave (R1) reflected from a surface of the second layer, a second terahertz wave (R2) reflected from an exposed surface of the first layer, and a third terahertz wave (R3) reflected from an interface formed by the first layer and the second layer; And it may include a calculation unit that calculates the refractive index of the second layer based on the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) and the detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and the detection time of the third terahertz wave (R3), and calculates the thickness of the second layer based on the calculated refractive index of the second layer.

[0098] Accordingly, a thickness measurement device and method can be provided that can obtain reliable thickness information on a thickness measurement target through the reflection mode of terahertz waves.

[0099] That is, according to an embodiment of the present invention, a thickness measurement device and method can be provided, which can calculate the refractive index of a thickness measurement object based on a time parameter at which terahertz waves irradiated toward and reflected from a thickness measurement object are detected, and can calculate the thickness of the thickness measurement object based on the calculated refractive index.

[0100] In particular, in the case where a metal and a non-metal are laminated, it was difficult to obtain accurate information on the refractive index and thickness using the conventional transmission mode, whereas according to an embodiment of the present invention, it is possible to obtain accurate information on the refractive index and thickness.

[0101] FIG. 1 is a block diagram showing a thickness measuring device according to one embodiment of the present invention.

[0102] FIG. 2 is a schematic diagram illustrating a terahertz wave irradiation unit of a thickness measurement device according to one embodiment of the present invention.

[0103] FIG. 3 is a schematic diagram illustrating a terahertz wave detection unit of a thickness measurement device according to one embodiment of the present invention.

[0104] Figure 4 is a graph for explaining the operation unit of a thickness measuring device according to one embodiment of the present invention.

[0105] FIG. 5 is a schematic diagram for explaining a method of specifying thickness for each point set on the surface of a thickness measurement target using a thickness measurement device according to one embodiment of the present invention.

[0106] Figure 6 is a thickness measurement mapping diagram for the entire area of ​​a thickness measurement target.

[0107] FIGS. 7 and 8 are schematic diagrams for explaining a method of measuring the thickness of an object when the incident angle is not 90° in a thickness measuring device according to one embodiment of the present invention.

[0108] Figure 9 is a flowchart illustrating a thickness measurement method according to one embodiment of the present invention.

[0109] Fig. 10 is a block diagram showing a thickness measuring device according to another embodiment of the present invention.

[0110] Fig. 11 is a schematic diagram illustrating a thickness measuring device according to another embodiment of the present invention.

[0111] FIG. 12 is a schematic diagram illustrating a terahertz wave irradiation unit of a thickness measurement device according to another embodiment of the present invention.

[0112] FIG. 13 is a schematic diagram illustrating a terahertz wave detection unit of a thickness measurement device according to another embodiment of the present invention.

[0113] Fig. 14 is a graph for explaining the operation unit of a thickness measuring device according to another embodiment of the present invention.

[0114] Figure 15 is a graph for explaining Example 1.

[0115] Figure 16 is a flowchart showing a thickness measurement method according to another embodiment of the present invention.

[0116] Fig. 17 is a block diagram showing a thickness measuring device according to another embodiment of the present invention.

[0117] FIG. 18 is a schematic diagram illustrating a terahertz wave irradiation unit of a thickness measurement device according to another embodiment of the present invention.

[0118] FIG. 19 is a schematic diagram illustrating a terahertz wave detection unit of a thickness measurement device according to another embodiment of the present invention.

[0119] Figure 20 is a graph for explaining the operation unit of a thickness measuring device according to another embodiment of the present invention.

[0120] FIG. 21 is a schematic diagram illustrating a method of measuring the thickness of an object when the incident angle is not 90° in a thickness measuring device according to another embodiment of the present invention.

[0121] Figure 22 is a graph for explaining Example 2.

[0122] Figure 23 is a flowchart illustrating a thickness measurement method according to another embodiment of the present invention.

[0123] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete and to sufficiently convey the spirit of the present invention to those skilled in the art.

[0124] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. Furthermore, in the drawings, shapes and sizes are exaggerated for the purpose of effectively explaining the technical contents.

[0125] Additionally, although terms such as first, second, and third have been used to describe various components in various embodiments of this specification, 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 embodiments. Additionally, the term "and / or" has been used herein to mean including at least one of the components listed before and after.

[0126] In the specification, singular expressions include plural expressions unless the context clearly dictates otherwise. In addition, terms such as "comprise" or "have" are intended to specify the presence of a feature, number, step, component, or combination thereof described in the specification, and should not be construed as excluding the presence or addition of one or more other features, numbers, steps, components, or combinations thereof. In addition, the term "connection" is used in the present specification to mean both indirectly connecting multiple components and directly connecting them.

[0127] In addition, when describing the present invention below, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0128]

[0129] FIG. 1 is a block diagram showing a thickness measuring device according to an embodiment of the present invention, FIG. 2 is a schematic diagram for explaining a terahertz wave irradiation unit of a thickness measuring device according to an embodiment of the present invention, FIG. 3 is a schematic diagram for explaining a terahertz wave detection unit of a thickness measuring device according to an embodiment of the present invention, FIG. 4 is a graph for explaining a calculation unit of a thickness measuring device according to an embodiment of the present invention, FIG. 5 is a schematic diagram for explaining a method for specifying a thickness for each point set on the surface of a thickness measurement target object through a thickness measuring device according to an embodiment of the present invention, FIG. 6 is a thickness measurement mapping diagram for the entire area of ​​a thickness measurement target object, and FIGS. 7 and 8 are schematic diagrams for explaining a method for measuring the thickness of an object when the incident angle is not 90° in a thickness measuring device according to an embodiment of the present invention.

[0130]

[0131] Referring to FIGS. 1 and 2, a thickness measuring device (100) according to an embodiment of the present invention is a device for measuring the thickness of a second layer (20), which is a thickness measurement target, in a specimen including a first layer (10) and a second layer (20) laminated on the first layer (10) in a form in which the edge of the first layer (10) is exposed upward.

[0132] At this time, the thickness measuring device (100) according to one embodiment of the present invention measures the thickness of the second layer (20) through the reflection mode of terahertz waves (THz waves), so even if the first layer (10) is made of metal, the thickness of the second layer (20) can be accurately measured.

[0133] A thickness measuring device (100) according to one embodiment of the present invention may include a terahertz wave irradiation unit (110), a terahertz wave detection unit (120), and a calculation unit (130).

[0134]

[0135] The above terahertz wave irradiation unit (110) is a device that irradiates terahertz waves toward the specimen. According to one embodiment of the present invention, the terahertz wave irradiation unit (110) can irradiate terahertz waves toward the edge of the second layer (20) so that terahertz waves are directly irradiated simultaneously to the first layer (10) and the second layer (20) at different heights through a single irradiation.

[0136] Accordingly, the terahertz wave emitted from the terahertz wave irradiation unit (110) can be irradiated to the surface of the second layer (20), and at the same time, can be irradiated to the exposed surface of the first layer (10), and at the same time, can be irradiated to the interface formed by the first layer (10) and the second layer (20).

[0137] At this time, according to one embodiment of the present invention, the terahertz wave irradiation unit (110) can irradiate terahertz waves in a direction perpendicular to the surface of the specimen.

[0138]

[0139] The above terahertz wave detection unit (120) can detect terahertz waves that are simultaneously irradiated to the first layer (10) and the second layer (20) and then reflected from their surfaces or interfaces. At this time, since the terahertz waves are irradiated perpendicularly to the first layer (10) and the second layer (20), they can be reflected vertically. Accordingly, the terahertz wave detection unit (120) can be positioned at a position where it can detect terahertz waves that are vertically reflected.

[0140] Referring to FIG. 3, the terahertz wave detection unit (120) can detect terahertz waves reflected from three parts of the specimen to provide data for calculating the thickness of the second layer (20) to the calculation unit (130).

[0141] Specifically, according to one embodiment of the present invention, the terahertz wave detection unit (120) can detect the first terahertz wave (R1) that is vertically irradiated onto the surface of the second layer (20) through the terahertz wave irradiation unit (110) and then vertically reflected from the surface.

[0142] In addition, the terahertz wave detection unit (120) can detect the second terahertz wave (R2) that is vertically reflected from the surface after being vertically irradiated onto the exposed surface of the first layer (10) through the terahertz wave irradiation unit (110).

[0143] And the above terahertz wave detection unit (120) can detect the third terahertz wave (R3) that is vertically reflected from the interface formed by the first layer (10) and the second layer (20) after being vertically irradiated to the interface through the terahertz wave irradiation unit (110).

[0144]

[0145] The above calculation unit (130) can calculate the refractive index of the specimen, more specifically, the second layer (20), which is a thickness measurement target, based on the time parameter of the terahertz wave irradiated to the specimen through the terahertz wave irradiation unit (110) and detected through the terahertz wave detection unit (120), and can calculate the thickness of the second layer (20) based on the calculated refractive index.

[0146] That is, as illustrated in FIG. 4, according to one embodiment of the present invention, the calculation unit (130) can calculate the refractive index of the second layer (20) based on the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) that is vertically irradiated onto the surface of the second layer (20) through the terahertz wave irradiation unit (110) and vertically reflected from the surface and the detection time of the second terahertz wave (R2) that is vertically irradiated onto the exposed surface of the first layer (10) through the terahertz wave irradiation unit (110) and vertically reflected from the surface, and the detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and the detection time of the third terahertz wave (R3) that is vertically irradiated onto the interface formed by the first layer (10) and the second layer (20) through the terahertz wave irradiation unit (110) and vertically reflected from the interface.

[0147] At this time, according to one embodiment of the present invention, when determining the detection time of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), the operation unit (130) may determine the detection time based on the maximum values ​​of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), as illustrated.

[0148] In addition, the operation unit (130) may determine the detection time based on the minimum values ​​of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), and may also determine the detection time as a middle value between the maximum and minimum values.

[0149] And the above calculation unit (130) can calculate the thickness of the second layer (20) based on the calculated refractive index of the second layer (20).

[0150] To this end, the operation unit (130) can define the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) as the following mathematical expression 1 regarding the thickness of the second layer (20) and the refractive index of air.

[0151]

[0152] [Formula 1]

[0153]

[0154]

[0155] At this time, the above calculation unit (130) can organize the above equation 1 into the following equation 2.

[0156]

[0157] [Formula 2]

[0158]

[0159]

[0160] Here, d1 is the thickness of the second layer (20), and n air is the refractive index of air, and C is the speed of light.

[0161] Meanwhile, according to one embodiment of the present invention, the calculation unit (130) can define the detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and the detection time of the third terahertz wave (R3) as the following mathematical expression 3 regarding the thickness of the second layer (20) and the refractive index of air.

[0162]

[0163] [Formula 3]

[0164]

[0165]

[0166] At this time, the above calculation unit (130) can organize the above equation 3 into the following equation 4.

[0167]

[0168] [Formula 4]

[0169]

[0170]

[0171] Here, d2 is the thickness of the second layer (20), C is the speed of light, and n s is the refractive index of the second layer (20).

[0172] Continuing, since d1 and d2 are the same as the thickness of the second layer (20), the above calculation unit (130) can substitute the above equation 2 into the above equation 3 to organize it into the following equation 5.

[0173]

[0174] [Formula 5]

[0175]

[0176]

[0177] And the above operation unit (130) calculates the refractive index (n) of the second layer (20) using the above formula 5. s ) can be summarized in Equation 6.

[0178]

[0179] [Formula 6]

[0180]

[0181]

[0182] According to one embodiment of the present invention, the operation unit (130) calculates the refractive index (n) of the second layer (20) through the above equation 6. s ) can be produced.

[0183] As confirmed in the above formula 6, the refractive index (n) of the second layer (20) s) can be calculated only by the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2), which is a time parameter, and the detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and the detection time of the third terahertz wave (R3).

[0184] At this time, according to one embodiment of the present invention, the calculation unit (130) calculates the thickness of the second layer (20) through the above equation 2 or the refractive index (n) of the second layer (20) calculated through the above equation 6 s ) can be applied to the above formula 4 to calculate the thickness of the second layer (20).

[0185] Meanwhile, a thickness measuring device (100) according to one embodiment of the present invention can measure the thickness for the entire area of ​​the second layer (20).

[0186] For this purpose, referring to FIG. 5, M (positive integer greater than or equal to 1) × N (positive integer greater than or equal to 1) points can be set on the surface of the second layer (20).

[0187] According to one embodiment of the present invention, the terahertz wave detection unit (120) can detect terahertz waves reflected at each of a plurality of points set on the surface of the second layer (20).

[0188] Accordingly, the above calculation unit (130) calculates the refractive index (n) of the second layer (20) through the above equation 6. s ) and the thickness for each point can be calculated using the following formula 7.

[0189]

[0190] [Formula 7]

[0191]

[0192]

[0193] Here, the above d mn Silver Point P mn is the thickness of the above Δt mnSilver Point P mn In , it is the detection time difference between the detection time of the first terahertz wave (R1) irradiated on the surface of the second layer (20) and reflected from this surface and the detection time of the third terahertz wave (R3) irradiated on the interface between the first layer (10) and the second layer (20) and reflected from this interface.

[0194] At this time, the above mn can define the coordinates of a point on the surface of the second layer (20). For example, point P 23 may refer to the coordinates of the point where the second column in the vertical direction and the third column in the horizontal direction intersect.

[0195] As illustrated in FIG. 6, the calculation unit (130) can visually display information about the thickness of each point of the generated second layer (20) by mapping it.

[0196] Meanwhile, as illustrated in FIGS. 7 and 8, according to one embodiment of the present invention, the terahertz wave is irradiated toward the edge of the second layer (20) through the terahertz wave irradiation unit (110) at an incident angle (θ) greater than 0° and less than 90°, and is reflected at an angle symmetrical to the incident angle (θ) and can be detected by the terahertz wave detection unit (120).

[0197] Accordingly, the calculation unit (130) can reflect the incident angle (θ) in the existing formula.

[0198] That is, according to one embodiment of the present invention, the calculation unit (130) can reflect the incident angle (θ) of the terahertz wave in the above equation 1, thereby converting the equation 1 into the following equation 8.

[0199]

[0200] [Formula 8]

[0201]

[0202]

[0203] At this time, the above calculation unit (130) can organize the above equation 8 into the following equation 9.

[0204]

[0205] [Formula 9]

[0206]

[0207]

[0208] The above equation 9 is a conversion equation that reflects the incident angle (θ) of the terahertz wave in the above equation 2.

[0209] In addition, the above calculation unit (130) can reflect the incident angle (θ) of the terahertz wave in the above equation 3, thereby converting the above equation 3 into the following equation 10.

[0210]

[0211] [Formula 10]

[0212]

[0213]

[0214] At this time, the above calculation unit (130) can organize the above equation 10 into the following equation 11.

[0215]

[0216] [Formula 11]

[0217]

[0218]

[0219] The above equation 11 is a conversion equation that reflects the incident angle (θ) of the terahertz wave in the above equation 4.

[0220] Continuing, the above operation unit (130) can substitute the above equation 9 into equation 10 to organize it into equation 12 below.

[0221]

[0222] [Formula 12]

[0223]

[0224]

[0225] According to one embodiment of the present invention, when the terahertz wave is not irradiated perpendicularly to the specimen, i.e., when the terahertz wave is irradiated toward the specimen at an incident angle (θ) greater than 0° and less than 90°, the calculation unit (130) calculates the refractive index (n) of the second layer (20) through the above equation 12. s ) can be produced.

[0226] In addition, the above calculation unit (130) calculates the thickness of the second layer (20) through the above equation 9 or the refractive index (n) of the second layer (10) calculated through the above equation 12. s ) can be applied to the above formula 11 to calculate the thickness of the second layer (20).

[0227]

[0228] Hereinafter, a thickness measurement method according to an embodiment of the present invention will be described with reference to FIG. 9.

[0229]

[0230] Figure 9 is a flowchart illustrating a thickness measurement method according to one embodiment of the present invention.

[0231]

[0232] Referring to FIG. 9, a thickness measurement method according to an embodiment of the present invention may include steps S110 to S130.

[0233]

[0234] S110 stage

[0235] In the above step S110, in a specimen including a first layer (10) and a second layer (20) laminated on the first layer (10) in a form in which the edge of the first layer (10) is exposed upward, terahertz waves can be irradiated toward the edge of the second layer (20).

[0236] At this time, in the above step S110, the terahertz waves can be irradiated toward the edge of the second layer (20) so that the terahertz waves can be directly irradiated simultaneously to the first layer (10) and the second layer (20) at different heights through a single investigation.

[0237] Accordingly, terahertz waves can be irradiated to the surface of the second layer (20), and simultaneously to the exposed surface of the first layer (10), and simultaneously to the interface formed by the first layer (10) and the second layer (20).

[0238]

[0239] S120 stage

[0240] In the above step S120, terahertz waves that are simultaneously irradiated to the first layer (10) and the second layer (20) and then reflected from their surfaces or interfaces can be detected.

[0241] Specifically, in the step S120, the first terahertz wave (R1) reflected from the surface of the second layer (20) after being irradiated can be detected. In addition, in the step S120, the second terahertz wave (R2) reflected from the exposed surface of the first layer (10) after being irradiated can be detected. In addition, in the step S120, the third terahertz wave (R3) reflected from the interface formed by the first layer (10) and the second layer (20) after being irradiated can be detected.

[0242]

[0243] Step S130

[0244] In the above step S130, the refractive index (n) of the second layer (20) is determined based on the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) irradiated on the surface of the second layer (20) and reflected from this surface and the detection time of the second terahertz wave (R2) irradiated perpendicularly to the exposed surface of the first layer (10) and reflected from this surface and the detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and the detection time of the third terahertz wave (R3) irradiated on the interface formed by the first layer (10) and the second layer (20) and reflected from this interface. s ) can be produced.

[0245] At this time, in the above step S130, the detection time can be determined based on the maximum values ​​of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3).

[0246] Additionally, in the step S130, the detection time may be determined based on the minimum values ​​of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), and the detection time may be determined based on the median value of the maximum and minimum values.

[0247] Next, in the above step S130, the refractive index (n) of the second layer (20) is calculated. s ) can be used to calculate the thickness (d) of the second layer (20).

[0248] According to one embodiment of the present invention, in the step S130, when the terahertz wave is irradiated vertically toward the edge of the sample, more specifically, the second layer (20), the refractive index (n) of the second layer (20) is determined through the above equation 6. s ) can be calculated, and the refractive index (n) of the calculated second layer (20) s ) can be applied to the above formula 4 to calculate the thickness (d) of the second layer (20).

[0249] In addition, in the above S130 step, when the terahertz wave is irradiated toward the edge of the sample, more specifically, the second layer (20), at an incident angle (θ) greater than 0° and less than 90°, the refractive index (n) of the second layer (20) is determined through the above equation 12. s ) can be calculated, and the refractive index (n) of the calculated second layer (20) s ) can be applied to the above formula 11 to calculate the thickness (d) of the second layer (20).

[0250] Meanwhile, in the step S130, when M (a positive integer greater than or equal to 1) × N (a positive integer greater than or equal to 1) points are set in a grid shape on the surface of the second layer (20), the thickness of each of the set points can be calculated using the above equations 6 and 7.

[0251] In this way, in the above step S130, the thickness of the entire surface of the second layer (20), that is, the entire surface of the second layer (20), is measured point by point, thereby providing information on the thickness deviation of the second layer (20).

[0252]

[0253] Hereinafter, a thickness measuring device according to another embodiment of the present invention will be described with reference to FIGS. 10 to 14.

[0254]

[0255] FIG. 10 is a block diagram showing a thickness measuring device according to another embodiment of the present invention, FIG. 11 is a schematic diagram for explaining a thickness measuring device according to another embodiment of the present invention, FIG. 12 is a schematic diagram for explaining a terahertz wave irradiation unit of a thickness measuring device according to another embodiment of the present invention, FIG. 13 is a schematic diagram for explaining a detection unit of a thickness measuring device according to another embodiment of the present invention, FIG. 14 is a graph for explaining a calculation unit of a thickness measuring device according to another embodiment of the present invention, and FIG. 15 is a graph for explaining Example 1.

[0256]

[0257] Referring to FIGS. 10 to 13, a thickness measuring device (200) according to another embodiment of the present invention is a device for measuring the thickness of a second layer (20), which is a thickness measurement target, in a specimen including a first layer (10) and a second layer (20) laminated on the first layer (10). At this time, the thickness measuring device (200) according to another embodiment of the present invention, like the thickness measuring device (100 of FIG. 1) according to one embodiment of the present invention, measures the thickness of the second layer (20) through the reflection mode of terahertz waves (THz waves), so even if the first layer (10) is made of metal, the thickness of the second layer (20) can be accurately measured.

[0258] A thickness measuring device (200) according to another embodiment of the present invention may include a terahertz wave irradiation unit (210), a terahertz wave detection unit (220), and a calculation unit (230).

[0259]

[0260] The above terahertz wave irradiation unit (210) can irradiate two terahertz waves (I1, I2) with different incident angles toward the second layer (20).

[0261] At this time, as illustrated in FIG. 11, the terahertz wave irradiation unit (210) may be equipped with two terahertz wave irradiation devices in order to irradiate two terahertz waves (I1, I2) with different incident angles. However, this is only an example, and the terahertz wave irradiation unit (210) may be equipped with one terahertz wave irradiation device, and accordingly, the one terahertz wave irradiation device may be moved to irradiate terahertz waves twice.

[0262]

[0263] The above terahertz wave detection unit (220) detects two first terahertz waves (R) reflected from the surface of the second layer (20) based on the position where the two terahertz waves (I1, I2) are reflected. 1S , R 2S ) can be detected.

[0264] In addition, the terahertz wave detection unit (220) detects two second terahertz waves (R) reflected at the interface formed by the first layer (10) and the second layer (20). 1T , R 2T ) can be detected.

[0265] This terahertz wave detection unit (220) can be equipped with two terahertz wave detection devices corresponding to the case where the terahertz wave irradiation unit (210) is equipped with two terahertz wave irradiation devices, and when one terahertz wave irradiation device moves and irradiates two terahertz waves (I1, I2) with different incident angles, four reflected terahertz waves ((R 1S , R 2S, R 1T , R 2T ) can be equipped with a single terahertz wave detection device that detects while moving.

[0266]

[0267] As shown in Fig. 14, the operation unit (230) generates two first terahertz waves (R) reflected from the surface of the second layer (20). 1S , R 2S ) of the first terahertz wave ((R 1S ) and the detection time of the two second terahertz waves (R) reflected at the interface formed by the first layer (10) and the second layer (20). 1T , R 2T ) of the second terahertz wave (R 1T ) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer (20), the difference in detection time (Δt1) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer (20) 1S , R 2S) of the other first terahertz wave ((R 2S ) and the detection time of the two second terahertz waves (R) reflected at the interface formed by the first layer (10) and the second layer (20). 1T , R 2T ) of the other second terahertz wave (R 2T ) and the incident angles (θ1, θ2) of the two terahertz waves (I1, I2) investigated above can be used to calculate the refractive index of the second layer (20).

[0268] At this time, according to another embodiment of the present invention, the operation unit (230) generates the first terahertz wave (R 1S , R 2S ) and the second terahertz wave (R 1T , R 2T ) when determining the detection time, the detection time can be determined based on their maximum value, the detection time can be determined based on their minimum value, or the detection time can be determined as a middle value between the maximum and minimum values.

[0269] Additionally, the incident angles (θ1, θ2) of the two terahertz waves (I1, I2) investigated above can be 0° to 90°.

[0270] According to another embodiment of the present invention, the calculation unit (230) can calculate the thickness of the second layer (20) based on the calculated refractive index of the second layer (20).

[0271] To this end, the above calculation unit (230) calculates the refractive index (n1) of the second layer (20) based on the investigated terahertz wave (I1), the speed of light (C), and the first terahertz wave ((R 1S ) detection time and the second terahertz wave (R 1T ) can be defined by the following equation 13 regarding the difference in detection time (Δt1) and the distance (l1) through which the investigated terahertz wave (I1) propagated within the second layer (20).

[0272]

[0273] [Formula 13]

[0274]

[0275]

[0276] In addition, the above operation unit (230) calculates the refractive index (n2) of the second layer (20) based on the investigated terahertz wave (I2), the speed of light (C), and the first terahertz wave ((R 2S ) detection time and the second terahertz wave (R 2T ) can be defined by the following equation 14 regarding the difference in detection time (Δt2) and the distance (l2) through which the investigated terahertz wave (I2) propagated within the second layer (20).

[0277]

[0278] [Formula 14]

[0279]

[0280]

[0281] At this time, the above calculation unit (230) calculates the distance (l1) at which the investigated terahertz wave (I1) propagates inside the second layer (20), the thickness (d1) of the second layer (20), the refractive index (n1) of the second layer (20), and the refractive index of air (n). air ) and the incident angle (θ1) of the investigated terahertz wave (I1) can be defined by the following equation 15.

[0282]

[0283] [Formula 15]

[0284]

[0285]

[0286] In addition, the above operation unit (230) calculates the distance (l2) that the investigated terahertz wave (I2) propagated inside the second layer (20) by the thickness (d2) of the second layer (20), the refractive index (n2) of the second layer (20), and the refractive index of air (n). air ) and the incident angle (θ2) of the investigated terahertz wave (I2) can be defined by the following equation 16.

[0287]

[0288] [Formula 16]

[0289]

[0290]

[0291] And the above calculation unit (230) substitutes the above equation 15 into the propagation distance (l1) of the above equation 13, substitutes the above equation 16 into the propagation distance (l2) of the above equation 14, and assuming that the refractive index (n1) of the second layer (20) based on the irradiated terahertz wave (I1) and the refractive index (n2) of the second layer (20) based on the irradiated terahertz wave (I2) have the same value and the thickness (d1) of the second layer (20) based on the irradiated terahertz wave (I1) and the thickness (d2) of the second layer (20) based on the irradiated terahertz wave (I2) have the same value, it can be defined by the following equation 17.

[0292]

[0293] [Formula 17]

[0294]

[0295]

[0296] According to another embodiment of the present invention, the operation unit (230) calculates the refractive index (n) of the second layer (20) through the above equation 17. s ) can be produced.

[0297] As confirmed in the above formula 17, the refractive index (n) of the second layer (20) s ) is the first terahertz wave ((R) which is a time parameter 1S ) detection time and the second terahertz wave (R 1T ) detection time difference (Δt1) and the first terahertz wave ((R 2S ) detection time and the second terahertz wave (R 2T ) can be calculated by the difference in detection time (Δt2) and the incident angle (θ1) of the investigated terahertz wave (I1) and the incident angle (θ2) of the investigated terahertz wave (I2).

[0298] At this time, according to another embodiment of the present invention, the operation unit (230) calculates the refractive index (n) of the second layer (20) calculated through the above formula 17. s ) can also be applied to calculate the thickness (d) of the second layer (20).

[0299]

[0300] Example 1

[0301] Referring to Fig. 15, in Example 1, a specimen composed of a first layer and a second layer laminated on the first layer is irradiated with terahertz waves at an incident angle (θ1) of 30° toward the second layer, and then the terahertz waves ((R)) reflected from the surface of the second layer are 1S ) and the terahertz wave (R) reflected from the interface between the first and second layers. 1T ) was measured. At the same time, after irradiating the terahertz wave with an incident angle (θ2) of 60°, the terahertz wave reflected from the surface of the second layer ((R 2S ) and the terahertz wave (R) reflected from the interface between the first and second layers. 2T ) was measured as the detection time difference (Δt2) between the detection times.

[0302] The above Δt1 was measured as 5.26419 ps, and the above Δt2 was measured as 5.7061 ps.

[0303] Substituting this measurement value into the above equation 17, the refractive index of the second layer (n s ) was calculated as 1.89951, and the thickness (d) of the second layer to which this was applied was calculated as 400.764 ㎛. At this time, the refractive index of air (n air ) is 1, and the speed of light (C) is 299792458 m / s.

[0304] Since the actual second layer thickness is 391.2㎛, the error rate of the calculated value, i.e. the measured value, was confirmed to be approximately 2.44%.

[0305]

[0306] Hereinafter, a thickness measurement method according to another embodiment of the present invention will be described with reference to FIG. 16.

[0307]

[0308] Figure 16 is a flowchart showing a thickness measurement method according to another embodiment of the present invention.

[0309]

[0310] Referring to FIG. 16, a thickness measurement method according to another embodiment of the present invention may include steps S210 to S230.

[0311]

[0312] Step S210

[0313] In the above step S210, two terahertz waves (I1, I2) having different incident angles to the second layer (20) can be irradiated toward the second layer (20). At this time, in the above step S210, the incident angles (θ1, θ2) of the two terahertz waves (I1, I2) to the second layer (20) can be set within 0° to 90°.

[0314]

[0315] Step S220

[0316] In the above step S220, based on the position where the two investigated terahertz waves (I1, I2) are reflected, the two first terahertz waves (R) reflected from the surface of the second layer (20) 1S , R 2S ) can be detected.

[0317] In addition, in the above step S220, two second terahertz waves (R) are reflected at the interface formed by the first layer (10) and the second layer (20). 1T , R 2T ) can be detected.

[0318]

[0319] Step S230

[0320] In the above step S230, two first terahertz waves (R) are reflected from the surface of the second layer (20). 1S , R 2S ) of the first terahertz wave ((R 1S ) and the detection time of the two second terahertz waves (R) reflected at the interface formed by the first layer (10) and the second layer (20). 1T , R 2T ) of the second terahertz wave (R 1T ) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer (20), the difference in detection time (Δt1) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer (20) 1S , R 2S ) of the other first terahertz wave ((R 2S ) and the detection time of the two second terahertz waves (R) reflected at the interface formed by the first layer (10) and the second layer (20). 1T , R 2T ) of the other second terahertz wave (R 2T ) and the incident angles (θ1, θ2) of the two terahertz waves (I1, I2) investigated above can be used to calculate the refractive index of the second layer (20).

[0321] At this time, in the above S230 step, the first terahertz wave (R 1S , R 2S ) and the second terahertz wave (R 1T , R 2T ) when determining the detection time, the detection time can be determined based on their maximum value, the detection time can be determined based on their minimum value, or the detection time can be determined as a middle value between the maximum and minimum values.

[0322] According to another embodiment of the present invention, in step S230, the first terahertz wave ((R 1S ) detection time and the second terahertz wave (R 1T ) detection time difference (Δt1) and the first terahertz wave ((R2S ) detection time and the second terahertz wave (R 2T ) detection time difference (Δt2) and the incident angle (θ1) of the investigated terahertz wave (I1) and the incident angle (θ2) of the investigated terahertz wave (I2) are substituted into the above equation 17 to obtain the refractive index (n) of the second layer (20). s ) can be calculated, and the refractive index (n) of the calculated second layer s ) can be used to calculate the thickness (d) of the second layer (20).

[0323]

[0324] Hereinafter, a thickness measuring device according to another embodiment of the present invention will be described with reference to FIGS. 17 to 22.

[0325]

[0326] Referring to FIGS. 17 to 19, a thickness measuring device (300) according to another embodiment of the present invention is a device for measuring the thickness of a second layer (20), which is a thickness measurement target, in a specimen including a first layer (10) and a second layer (20) laminated on the first layer (10). At this time, the thickness measuring device (300) according to another embodiment of the present invention measures the thickness of the second layer (20) through the reflection mode of terahertz waves (THz waves), so even if the first layer (10) is formed of metal, the thickness of the second layer (20) can be measured.

[0327] A thickness measuring device (300) according to another embodiment of the present invention may include a terahertz wave irradiation unit (310), a terahertz wave detection unit (320), and a calculation unit (330).

[0328]

[0329] The above terahertz wave irradiation unit (310) can irradiate terahertz waves toward the second layer (20). At this time, the terahertz wave irradiation unit (310) can irradiate terahertz waves in a direction perpendicular to the surface of the specimen, more specifically, the second layer (20).

[0330]

[0331] The above terahertz wave detection unit (320) can detect a first terahertz wave (R1) that is vertically reflected from the surface of the second layer (20) based on the position where the terahertz wave is reflected. In addition, the terahertz wave detection unit (320) can detect a second terahertz wave (R2) that is vertically reflected from the interface formed by the first layer (10) and the second layer (20). In addition, the terahertz wave detection unit (320) can detect a third terahertz wave (R3) that is reflected once more inside the second layer (20).

[0332]

[0333] Referring to FIG. 20, the calculation unit (330) can calculate the refractive index of the second layer (20) based on the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) that is vertically irradiated onto the surface of the second layer (20) through the terahertz wave irradiation unit (310) and vertically reflected from the surface and the detection time of the second terahertz wave (R2) that is vertically irradiated onto the interface formed by the first layer (10) and the second layer (20) through the terahertz wave irradiation unit (310) and vertically reflected from the interface, and the signal intensities (I1, I2, I3) of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3).

[0334] At this time, according to another embodiment of the present invention, when determining the detection time of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), the operation unit (330) may determine the detection time based on the maximum values ​​of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), as illustrated.

[0335] In addition, the operation unit (130) may determine the detection time based on the minimum values ​​of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), and may also determine the detection time as a middle value between the maximum and minimum values.

[0336] And, when the above-described calculation unit (330) determines the signal intensity of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), as illustrated, the signal intensity may be determined based on the maximum value of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), the signal intensity may be determined based on the minimum value thereof, or the signal intensity may be determined as a middle value between the maximum value and the minimum value.

[0337] And the above calculation unit (330) can calculate the thickness of the second layer (20) based on the calculated refractive index of the second layer (20).

[0338] To this end, the above calculation unit (330) can define the relationship between reflectance (R) and transmittance (T) as the following equation 18.

[0339]

[0340] [Formula 18]

[0341]

[0342]

[0343] In addition, the above operation unit (330) converts the signal intensities (I1, I2, I3) corresponding to the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3) into the reflectance (R), the transmittance (T), the absorption rate (A), and the basic signal intensity (I) expressed by the following equations 19 to 21. ref ) can be defined as.

[0344]

[0345] [Formula 19]

[0346]

[0347]

[0348] [Formula 20]

[0349]

[0350]

[0351] [Formula 21]

[0352]

[0353]

[0354] At this time, the above operation unit (330) can organize the above equation 18 into the following equation 22.

[0355]

[0356] [Formula 22]

[0357]

[0358]

[0359] In addition, the above operation unit (330) can organize the above equation 19 into the following equation 23.

[0360]

[0361] [Formula 23]

[0362]

[0363]

[0364] And the above operation unit (330) can organize the above equation 20 into the following equation 24.

[0365]

[0366] [Formula 24]

[0367]

[0368]

[0369] Continuing, the above operation unit (330) can substitute the above equations 22 to 23 into the above equation 21 to organize it into the following equation 25.

[0370]

[0371] [Formula 25]

[0372]

[0373]

[0374] Continuing, the above calculation unit (330) solves the above equation 25 to obtain the following equation 26 for transmittance (T), the following equation 27 for reflectance (R), the following equation 28 for absorption (A), and the following equation 29 for basic signal intensity (I ref ) can be derived from the following equation 29.

[0375]

[0376] [Formula 26]

[0377]

[0378]

[0379] [Formula 27]

[0380]

[0381]

[0382] [Formula 28]

[0383]

[0384]

[0385] [Formula 29]

[0386]

[0387]

[0388] At this time, the above operation unit (330) calculates the reflectance (R) of the second layer (20) and the refractive index (n) of the second layer (20). s ) and the refractive index of air (n air ) relationship can be defined as the following equation 30.

[0389]

[0390] [Formula 30]

[0391]

[0392]

[0393] And the above operation unit (330) calculates the thickness (d) of the second layer (20) by the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) and the refractive index (n s ) can be defined by the following equation 31.

[0394]

[0395] [Formula 31]

[0396]

[0397]

[0398] Here, C is the speed of light.

[0399] Continuing, the operation unit (330) substitutes the reflectance (R) of the above equation 27 into the above equation 30 to obtain the refractive index (n s ) can be derived from the following equation 32.

[0400]

[0401] [Formula 32]

[0402]

[0403]

[0404] According to another embodiment of the present invention, the operation unit (330) calculates the refractive index (n) of the second layer (20) through the above equation 32. s ) can be produced.

[0405] Continuing, the operation unit (330) calculates the refractive index (n) of the second layer (20) through the above equation 27 in the above equation 31. s ) can be substituted to derive the following equation 33 regarding the thickness (d) of the second layer (20).

[0406]

[0407] [Formula 33]

[0408]

[0409]

[0410] According to another embodiment of the present invention, the calculation unit (330) can calculate the thickness (d) of the second layer (20) through the above equation 33.

[0411] As confirmed in the above equations 32 and 33, the refractive index (n) of the second layer (20) s ) and the thickness (d) of the second layer (20) can be calculated only by the signal intensities (I1, I2, I3) corresponding to the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3) and the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) that is vertically irradiated to the surface of the second layer (20) through the terahertz wave irradiation unit (310) and vertically reflected from the surface, and the detection time of the second terahertz wave (R2) that is vertically irradiated to the interface formed by the first layer (10) and the second layer (20) through the terahertz wave irradiation unit (310) and vertically reflected from the interface.

[0412] Meanwhile, as illustrated in FIG. 21, according to another embodiment of the present invention, the terahertz wave is irradiated toward the second layer (20) through the terahertz wave irradiation unit (310) at an incident angle (θ) greater than 0° and less than 90°, and then reflected from the surface of the second layer (20) and the interface formed by the first layer (10) and the second layer (20), and can be detected by the terahertz wave detection unit (120).

[0413] Accordingly, the calculation unit (130) can reflect the incident angle (θ) in the existing formula.

[0414] That is, according to another embodiment of the present invention, the calculation unit (330) can define the reflectivity (R) of the second layer (20) according to the incident angle (θ) of the terahertz wave using the following equation 34.

[0415]

[0416] [Formula 34]

[0417]

[0418]

[0419] According to another embodiment of the present invention, when the terahertz wave is not irradiated perpendicularly to the specimen, i.e., when the terahertz wave is irradiated toward the specimen at an incident angle (θ) greater than 0° and less than 90°, the calculation unit (330) calculates the refractive index (n) of the second layer (20) through the above equation 34. s ) can be produced.

[0420] In addition, the above calculation unit (330) can reflect the incident angle (θ) of the terahertz wave in the above equation 31, thereby converting the above equation 31 into the following equation 35.

[0421]

[0422] [Formula 35]

[0423]

[0424]

[0425] At this time, the above θ α can be defined by the following equation 36.

[0426]

[0427] [Formula 36]

[0428]

[0429]

[0430] The above calculation unit (330) can substitute the above equation 36 into the above equation 35 to derive the following equation 37 regarding the thickness (d) of the second layer (20).

[0431]

[0432] [Formula 37]

[0433]

[0434]

[0435] According to another embodiment of the present invention, the calculation unit (330) can calculate the thickness (d) of the second layer (20) through the above equation 33 when the terahertz wave is irradiated perpendicularly to the specimen, and can calculate the thickness (d) of the second layer (20) through the above equation 37 when the terahertz wave is not irradiated perpendicularly to the specimen, that is, when the terahertz wave is irradiated at an incident angle (θ) greater than 0° and less than 90° toward the specimen.

[0436]

[0437] Example 2

[0438] Referring to FIG. 22, in Example 2, after irradiating terahertz waves vertically at points A.1, A.2, A.3, and A.4 set on a silicon wafer specimen, the detection time difference (Δt1) between the detection time of the terahertz wave (R1) vertically reflected from the upper layer surface and the detection time of the terahertz wave (R2) vertically reflected at the interface between the upper layer and the lower layer, and the signal intensities (I1, I2, I3) of the terahertz wave (R1) vertically reflected from the upper layer surface, the terahertz wave (R2) vertically reflected at the interface between the upper layer and the lower layer, and the terahertz wave (R3) vertically reflected once more inside the upper layer were measured.

[0439] And by substituting the detection time difference (Δt1) and signal intensity (I1, I2, I3) into Equations 32 and 33, the refractive index (n) of each point A.1, A.2, A.3 and A.4 is obtained. s ) and thickness (d) were calculated. Table 1 below shows the refractive indices (n) calculated for each of the points A.1, A.2, A.3 and A.4. s ) and thickness (d).

[0440]

[0441] pointl1(au)l2(au)l3(au)△t1(ps)n s d(㎛)d act(㎛)error(%)A.1112.64301.2998.142.491.98188.39184.22.27A.2102.66296.20102.492.45197185.9918 1.82.30A.3104.04288.6297.272.491.98188.541833.03A.4102.48295.83102.012.481.97188.751833.14

[0442]

[0443] As shown in Table 1 above, the thickness (d) measurement results for each point of the silicon wafer through Example 2 are obtained by using a microscope. act ) It can be confirmed that the error rate is within 4% when compared with the measurement results.

[0444]

[0445] Hereinafter, a thickness measurement method according to another embodiment of the present invention will be described with reference to FIG. 23.

[0446]

[0447] Figure 23 is a flowchart illustrating a thickness measurement method according to another embodiment of the present invention.

[0448]

[0449] Referring to FIG. 23, a thickness measurement method according to another embodiment of the present invention may include steps S310 to S330.

[0450]

[0451] S310 stage

[0452] In the above step S310, in a specimen including a first layer (10) and a second layer (20) laminated on the first layer (10), terahertz waves can be irradiated toward the second layer (20), which is the upper layer.

[0453]

[0454] S320 stage

[0455] In the above step S320, the first terahertz wave (R1) reflected from the surface of the second layer (20) can be detected after being irradiated.

[0456] In addition, in the step S320, the second terahertz wave (R2) that is irradiated to the interface formed by the first layer (10) and the second layer (20) and then reflected from the interface can be detected. In addition, in the step S320, the third terahertz wave (R3) that is irradiated to the second interface and then reflected, then reflected again from the surface of the second layer (20) and then reflected from the interface can be detected.

[0457]

[0458] S330 stage

[0459] In the above step S330, the refractive index (n) of the second layer (20) is determined based on the detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) and the signal intensities (I1, I2, I3) of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3). s ) can be produced.

[0460] At this time, in step S330, the detection time can be determined based on the maximum values ​​of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3). In addition, in step S330, the detection time can be determined based on the minimum values ​​of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), and the detection time can be determined as a middle value between the maximum and minimum values.

[0461] At this time, in the step S330, the signal intensity may be determined based on the maximum values ​​of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), the signal intensity may be determined based on the minimum values ​​thereof, or the signal intensity may be determined as a middle value between the maximum and minimum values.

[0462] Next, in the above S330 step, the refractive index (n) of the second layer (20) is calculated. s ), the thickness (d) of the second layer (20) can be calculated.

[0463] According to another embodiment of the present invention, in the step S330, when the terahertz wave is irradiated vertically toward the surface of the specimen, more specifically, the second layer (20), the refractive index (n) of the second layer (20) is determined through the equation 32. s ) can be calculated, and the refractive index (n) of the calculated second layer (20) s ) can be applied to the above formula 33 to calculate the thickness (d) of the second layer (20).

[0464] In addition, in the above S330 step, when the terahertz wave is irradiated toward the surface of the sample, more specifically, the second layer (20), at an incident angle (θ) greater than 0° and less than 90°, the refractive index (n) of the second layer (20) is determined through the above equation 34. s ) can be calculated, and the refractive index (n) of the calculated second layer (20) s ) can be applied to the above formula 37 to calculate the thickness (d) of the second layer (20).

[0465]

[0466] In this way, according to embodiments of the present invention, a thickness measurement device (100, 200, 300) and method capable of obtaining reliable thickness information on a second layer (20), which is a thickness measurement target, through the reflection mode of terahertz waves can be provided.

[0467]

[0468] While the present invention has been described in detail using preferred embodiments, the scope of the present invention is not limited to the specific embodiments described above, and should be interpreted in accordance with the appended claims. Furthermore, those skilled in the art will appreciate that numerous modifications and variations are possible without departing from the scope of the present invention.

Claims

1. A thickness measuring device for measuring the thickness of a second layer in a specimen including a first layer and a second layer laminated on the first layer in a form in which the edge of the first layer is exposed upward, A terahertz wave irradiation unit that irradiates the terahertz wave toward the edge of the second layer so that the terahertz wave is directly irradiated to the first layer and the second layer simultaneously through a single investigation; A terahertz wave detection unit that detects a first terahertz wave (R1) reflected from the surface of the second layer, a second terahertz wave (R2) reflected from the exposed surface of the first layer, and a third terahertz wave (R3) reflected from the interface formed by the first layer and the second layer, based on the position where the terahertz wave investigated above is reflected; and A thickness measuring device, comprising: a calculation unit for calculating the refractive index of the second layer based on a detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) and a detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and the detection time of the third terahertz wave (R3), and calculating the thickness of the second layer based on the calculated refractive index of the second layer.

2. In paragraph 1, The above operation unit calculates the refractive index (n) of the second layer through the following equation 6 s ) a thickness measuring device. [Formula 6] Here, the above n air is the refractive index of air.

3. In paragraph 2, The detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) is defined by the following equation 1, and the detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and the detection time of the third terahertz wave (R3) is defined by the following equation 3. The above formula 1 is summarized as the following formula 2, the above formula 3 is summarized as the following formula 4, the above formulas 2 and 3 are summarized as the following formula 5, and the above formula 5 is summarized as the above formula 6, The above calculation unit is a thickness measuring device that calculates the thickness of the second layer through the above equation 2 or equation 4. [Formula 1] [Formula 2] [Formula 3] [Formula 4] [Formula 5] Here, C is the speed of light, and d1 and d2 are the thicknesses of the second layer.

4. In paragraph 3, The above terahertz wave detection unit detects terahertz waves reflected at each of M (a positive integer greater than or equal to 1) × N (a positive integer greater than or equal to 1) points set on the surface of the second layer, The above calculation unit is a thickness measuring device that calculates the thickness for each point through the following equation 7. [Formula 7] 5. In paragraph 3, A thickness measuring device that calculates the thickness of the second layer when the terahertz wave irradiation unit irradiates the terahertz wave at an incident angle (θ) greater than 0° and less than 90° toward the edge of the second layer, through the following equation 8 converted from the above equation 1, the following equation 9 converted from the above equation 2, the following equation 10 converted from the above equation 3, the following equation 11 converted from the above equation 4, and the following equation 12 converted from the above equation 5. [Formula 8] [Formula 9] [Formula 10] [Formula 11] [Formula 12] 6. A thickness measuring device for measuring the thickness of a second layer in a specimen including a first layer and a second layer laminated on the first layer, A terahertz wave irradiation unit that irradiates two terahertz waves (I1, I2) with different incident angles toward the second layer; Based on the positions where the two terahertz waves (I1, I2) investigated above are reflected, the two first terahertz waves (R) reflected from the surface of the second layer 1S , R 2S ) and two second terahertz waves (R) reflected at the interface formed by the first layer and the second layer. 1T , R 2T ) a terahertz wave detection unit; and Two first terahertz waves (R) reflected from the surface of the second layer 1S , R 2S ) of the first terahertz wave ((R 1S ) and the detection time of the two second terahertz waves (R) reflected from the interface formed by the first and second layers. 1T , R 2T ) of the second terahertz wave (R 1T ) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer, the difference in detection time (Δt1) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer. 1S , R 2S ) of the other first terahertz wave ((R 2S ) and the detection time of the two second terahertz waves (R) reflected from the interface formed by the first and second layers. 1T , R 2T ) of the other second terahertz wave (R 2T ) and the incident angles (θ1, θ2) of the two terahertz waves (I1, I2) investigated, and calculates the refractive index of the second layer based on the calculated refractive index of the second layer, and calculates the thickness of the second layer based on the calculated refractive index of the second layer.

7. In paragraph 6, The above operation unit calculates the refractive index (n) of the second layer through the following equation 17. s ) a thickness measuring device. [Formula 17] Here, the above n air is the refractive index of air, C is the speed of light, θ1 is the incident angle of one of the two terahertz waves (I1, I2) investigated to the second layer, θ2 is the incident angle of the other of the two terahertz waves (I1, I2) investigated to the second layer, and d1 and d2 are the thicknesses of the second layer.

8. In paragraph 7, The above formula 17 is a thickness measuring device derived through formulas 13 to 16 below. [Formula 13] [Formula 14] [Formula 15] [Formula 16] Here, l1 is a distance at which one of the two terahertz waves (I1, I2) investigated is propagated within the second layer, l2 is a distance at which the other of the two terahertz waves (I1, I2) investigated is propagated within the second layer, and n1 and n2 are refractive indices of the second layer.

9. A thickness measuring device for measuring the thickness of a second layer in a specimen including a first layer and a second layer laminated on the first layer, A terahertz wave irradiation unit that irradiates terahertz waves toward the second layer; A terahertz wave detection unit that detects a first terahertz wave (R1) reflected from the surface of the second layer, a second terahertz wave (R2) reflected from the interface formed by the first layer and the second layer, and a third terahertz wave (R3) reflected once more inside the second layer, based on the position where the terahertz wave investigated above is reflected; and A thickness measuring device, comprising: a calculation unit for calculating the refractive index of the second layer based on a detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) and signal intensities (I1, I2, I3) of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), and calculating the thickness of the second layer based on the calculated refractive index of the second layer.

10. In paragraph 9, The above operation unit calculates the refractive index (n) of the second layer through the following equation 32 s ) and calculates the thickness (d) of the second layer through the following equation 33. [Formula 32] [Formula 33] 11. In paragraph 10, A thickness measuring device in which, when the terahertz wave irradiation unit irradiates the terahertz wave toward the second layer at an incident angle (θ) greater than 0° and less than 90°, the calculation unit calculates the thickness (d) of the second layer through the following equation 37 converted from the equation 33. [Formula 37] 12. A step of irradiating terahertz waves toward the edge of the second layer so that the first layer and the second layer are directly irradiated simultaneously to the first layer and the second layer through a single irradiation, for a specimen including a first layer and a second layer laminated on the first layer in a form in which the edge of the first layer is exposed upward; A step of detecting a first terahertz wave (R1) reflected from the surface of the second layer, a second terahertz wave (R2) reflected from the exposed surface of the first layer, and a third terahertz wave (R3) reflected from the interface formed by the first layer and the second layer based on the position where the terahertz wave investigated above is reflected; and A thickness measuring method, comprising: calculating a refractive index of the second layer based on a detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) and a detection time difference (Δt2) between the detection time of the first terahertz wave (R1) and the detection time of the third terahertz wave (R3), and calculating a thickness of the second layer based on the calculated refractive index of the second layer.

13. For a specimen including a first layer and a second layer laminated on the first layer, a step of irradiating two terahertz waves (I1, I2) at different angles of incidence with respect to the second layer toward the second layer; Based on the positions where the two terahertz waves (I1, I2) investigated above are reflected, the two first terahertz waves (R) reflected from the surface of the second layer 1S , R 2S ) and two second terahertz waves (R) reflected at the interface formed by the first layer and the second layer. 1T , R 2T ) detecting step; and Two first terahertz waves (R) reflected from the surface of the second layer 1S , R 2S ) of the first terahertz wave ((R 1S ) and the detection time of the two second terahertz waves (R) reflected from the interface formed by the first and second layers. 1T , R 2T ) of the second terahertz wave (R 1T ) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer, the difference in detection time (Δt1) between the detection times of the first terahertz waves (R) reflected from the surface of the second layer. 1S , R 2S ) of the other first terahertz wave ((R 2S ) and the detection time of the two second terahertz waves (R) reflected from the interface formed by the first and second layers. 1T , R 2T ) of the other second terahertz wave (R 2T ) and the incident angles (θ1, θ2) of the two investigated terahertz waves (I1, I2) based on the detection time difference (Δt2) between the detection times of the second layer, and calculating the refractive index of the second layer based on the calculated refractive index of the second layer; a thickness measurement method comprising the step of calculating the thickness of the second layer.

14. For a specimen including a first layer and a second layer laminated on the first layer, a step of irradiating terahertz waves toward the second layer; A step of detecting a first terahertz wave (R1) reflected from the surface of the second layer, a second terahertz wave (R2) reflected from the interface formed by the first layer and the second layer, and a third terahertz wave (R3) reflected once more inside the second layer based on the position where the terahertz wave investigated above is reflected; and A thickness measurement method, comprising: calculating a refractive index of the second layer based on a detection time difference (Δt1) between the detection time of the first terahertz wave (R1) and the detection time of the second terahertz wave (R2) and signal intensities (I1, I2, I3) of the first terahertz wave (R1), the second terahertz wave (R2), and the third terahertz wave (R3), and calculating a thickness of the second layer based on the calculated refractive index of the second layer.

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