Hole depth measurement method using phase extraction information on reflection spectrum, measurement system and computer readable medium

Abstract

To provide a hole depth measurement method using phase extraction information on a reflection spectrum, a measurement system and a computer readable medium.SOLUTION: A hole depth measurement method includes an acquisition step for a reflection spectrum, an acquisition step for correlation between reflected light intensity and a wave number, a phase extraction step, and a determination step for hole depth. First distribution data between the reflected light intensity and wave number is converted into second distribution data between a phase and the wave number, and a gradient value is calculated to obtain hole depth information on a hole structure. Measurement resolution can be thus increased and precision also can be improved.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a structure measurement technique, and more particularly to a hole depth measurement method, a measurement system, and a computer-readable medium using phase extraction information of a reflection spectrum.

Background Art

[0002] In the technical field of semiconductor integrated circuits, in order to increase space utilization and improve the problem of data transmission bottlenecks, semiconductor integrated circuits have entered a three-dimensional (2.5D, 3D, etc.) mounting process, and the above problems are solved by a bare chip stacking method.

[0003] In these stacked structures, through the Through Silicon Via (TSV) technology, signals of different chips can be connected to each other, space utilization can be improved, and the conduction distance can be shortened, thereby achieving an improvement in the transmission speed of signals and power.

[0004] In the manufacturing process of silicon through holes (TSVs), there are multiple processes due to some differences in manufacturing. Generally speaking, examples of these processes include via formation, via filling, chemical-mechanical polishing (CMP), wafer thinning, wafer bonding, and various TSV integration technologies (Via First, Via Last), etc.

[0005] Since the via is the basis of the entire silicon through hole structure, the depth dimension of the hole plays an important role in the entire silicon through hole manufacturing process and must be accurately grasped. However, since the via of the silicon through hole structure has the structural feature of a high aspect ratio, it is difficult to measure the depth of the hole, and the measurement accuracy faces a greater challenge.

Summary of the Invention

Means for Solving the Problems

[0006] In some embodiments disclosed by the present invention, the accuracy is improved by increasing the measurement resolution of the hole depth.

[0007] According to some embodiments, the present invention provides a method for measuring a hole depth using phase extraction information of a reflection spectrum, including steps of obtaining a reflection spectrum from a target region having a high aspect ratio hole structure, obtaining first distribution data between a reflected light intensity and a wave number based on the reflection spectrum, converting the first distribution data into second distribution data between a phase and a wave number through a phase extraction process, and determining the hole depth of the hole structure and a wavelength unit of the reflection spectrum as a measurement unit of the hole depth based on an inclination value of at least one straight line indicated by the second distribution data.

[0008] According to some embodiments, when the second distribution data shows a single straight line, half of the inclination value of the straight line is the hole depth of the hole structure.

[0009] According to some embodiments, the phase extraction process may include deleting a DC term in the first distribution data, performing a Hilbert transform to obtain an analytic signal having a real part term in the form of a cosine and an imaginary part term in the form of a sine, and obtaining a distribution relationship between a phase and a wave number as the second distribution data based on an arctangent function of the real part term and the imaginary part term.

[0010] According to some embodiments, the phase extraction process may include converting the first distribution data into intermediate conversion data having a real part term and an imaginary part term, performing a Fourier transform, retaining only one of the real part term or the imaginary part term and deleting other data, performing a point deletion and filling step of filling complex data points with a fixed power density value to maintain the data length, performing an inverse Fourier transform, and obtaining a distribution relationship between a phase and a wave number as the second distribution data.

[0011] According to some embodiments, when the peripheral surface of the hole structure has a light-transmissive oxide layer, the phase data in the first distribution data defines a hole depth phase and a thin film phase, and two straight lines can be shown in the second distribution data. The slope value of the straight line with the larger slope among the two straight lines is a first value, and the slope value of the straight line with the smaller slope among the two straight lines is a second value. Half of the second value may be the thickness of the oxide layer. Half of the sum of the first value and the second value may be the hole depth of the hole structure. The wavelength unit of the reflection spectrum may be the measurement unit of the thickness of the oxide layer.

[0012] According to some embodiments, the present invention further provides a non-volatile computer-readable storage medium capable of storing a computer program. The computer program is used to be loaded into an arithmetic processing unit and can be used to cause the arithmetic processing unit to execute the method described above.

[0013] According to some embodiments, the present invention further provides a hole depth measurement system using phase extraction information of a reflection spectrum, including an optical interference measurement device and an arithmetic processing unit. The optical interference measurement device can be used to obtain a reflection spectrum from a target area. The arithmetic processing unit is coupled to the optical interference measurement device and can be used to execute the method described above.

Advantages of the Invention

[0014] Therefore, based on the relationship between the reflected light intensity and the wave number, a distribution relationship between the phase and the wave number can be obtained through conversion. Subsequently, a linear distribution relationship is shown, and the hole depth information of the hole structure can be obtained by calculating the slope value. Furthermore, the thickness information of the oxide layer can also be obtained. The measurement resolution can be improved, and the accuracy can also be enhanced.

Brief Description of the Drawings

[0015]

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DETAILED DESCRIPTION OF THE INVENTION

[0016] To fully understand the object, features, and effects of the present invention, the present invention will be described in detail below in combination with the drawings attached to specific examples.

[0017] The terms "a" or "one" as used in this specification are used to describe units, components, structures, devices, modules, systems, parts, or regions, etc. This is for the sole purpose of convenience of explanation and is made to give a general meaning to the scope of the present invention. Therefore, unless the context clearly indicates otherwise, such descriptions should be understood to include one or at least one, and the singular form also includes the plural.

[0018] As used herein, the terms "comprising," "including," "having," or other similar terms are not limited to the elements listed herein, and may include other elements that are commonly inherent to a unit, component, structure, device, module, system, part, or region, although not explicitly described.

[0019] As used herein, similar ordinal terms such as "first" or "second" are used to distinguish or refer to the same or similar elements, structures, parts, or regions, and do not necessarily imply the spatial order of these elements, structures, parts, or regions. It should be understood that in some cases or configurations, the ordinal terms can be used interchangeably without affecting the implementation of the present invention.

[0020] FIG. 1 is a schematic diagram of a hole structure. After irradiating the hole structure having a hole depth h with detection light, the incident light forms a first reflected light R1 on the surface around the hole structure 300, and the incident light forms a second reflected light R2 at the bottom of the hole of the hole structure 300. There is an optical path difference between the first reflected light R1 and the second reflected light R2, and based on the information of this optical path difference, the hole depth h of the hole structure 300 can be obtained.

[0021] FIG. 2 is a schematic diagram of a measurement system according to some embodiments. The measurement system includes an optical interference measurement device 100 and an arithmetic processing device 200. The optical interference measurement device 100 irradiates the object to be measured x having the hole structure 300 with illumination light 101 and is used to scan the target area (irradiating illumination light one hole or one area at a time). When the illumination light is irradiated onto one hole or one area once, a corresponding interference signal can be obtained. In some embodiments, each scanning measurement operation of the optical interference measurement device 100 is performed only for a single hole (irradiating illumination light and acquiring the reflection spectrum). In this way, the related information of the hole structure can be determined quickly and accurately.

[0022] Due to the coaxial illumination configuration of the light source unit 120 and the spectroscopic unit 130, the reflected light from the hole structure 300 can be captured by the imaging unit 110 to form a spectral signal. Based on the aforementioned optical path difference, the imaging unit 110 can capture a spectral signal with an interference phenomenon from the object to be measured having the hole structure 300. The arithmetic processing unit 200 is coupled to the light source unit 120 and the imaging unit 110 of the optical interference measurement device 100, performs a scanning operation, receives the spectral signal, and executes subsequent processing steps such as phase extraction.

[0023] The configuration of the optical interference measurement device 100 in FIG. 2 is merely an example. Any optical interference measurement device, such as a spectral interferometer or other types of interferometers, in other words, a measurement device that can obtain the reflected light from the reference surface (surface) of the object to be measured and the reflected light from the bottom of the hole structure of the hole structure and obtain the optical interference phenomenon between the two, can be applied to the embodiments of the present invention. The arithmetic processing unit 200 can be a single computer, a plurality of computers, or a single arithmetic processing module or a plurality of arithmetic processing modules configured within the entire measurement system. The arithmetic processing unit 200 receives the spectral signal of the reflected light provided by the optical interference measurement device 100 and is used for processing.

[0024] Next, FIG. 3 is a flowchart of a hole depth measurement method using phase extraction information of a reflection spectrum according to some embodiments.

[0025] The arithmetic processing unit 200 is configured to execute the following hole depth measurement method.

[0026] Step S110: A step of acquiring a reflection spectrum. In this step, a reflection spectrum from a target region is acquired. The target region has a high aspect ratio hole structure. The target region may have only a single hole structure or a plurality of hole structures.

[0027] Step S120: A step of obtaining the correlation between the reflected light intensity and the wave number. In this step, based on the reflection spectrum, the correlation between the light intensity of the reflected light and the wave number is converted into a distribution relationship that can show the correlation, so as to obtain first distribution data representing the correlation between the light intensity and the wave number.

[0028] Step S130: A phase extraction step. In this step, the first distribution data is converted by a phase extraction process into a distribution relationship that can show the correlation between the phase and the wave number, so as to obtain second distribution data representing the correlation between the phase and the wave number.

[0029] Step S140: A hole depth determination step. In this step, the hole depth of the hole structure is determined based on the slope value of at least one straight line that can be shown by the second distribution data. The wavelength unit of the reflection spectrum is used as the measurement unit of the hole depth.

[0030] Light has sine wave characteristics, and different reflected lights from the surface around the hole structure (e.g., the top of the hole) and the bottom of the hole structure can cause the redistribution of the light intensity in space based on the optical path difference, forming an interference phenomenon. By extracting the phase information in the reflection spectrum, the distribution relationship between the phase and the wave number can be obtained, and this distribution relationship can be used to obtain the hole depth information of the hole structure. In addition, the resolution can be effectively improved.

[0031] In some embodiments, in step S120, the corresponding light intensity values can be obtained based on the wave numbers at the same intervals. Therefore, when the wavelengths in the reflection spectrum data are converted into wave numbers, the interpolation values of the corresponding light intensity values can be obtained by a general interpolation method or other methods.

[0032] Next, FIG. 4 is a graph showing the relationship between the reflected light intensity and the wave number according to some embodiments. The wave number is the number of wavelengths per length of 2π, or the number of repetitions of the wave per length of 2π. When the wave number is defined as k, k = 2π / λ.

[0033] When there is an interference phenomenon based on the optical path difference in the reflection spectrum, the optical path difference is twice the hole depth (when incident and reflected, it further moves a distance of h). The number of wavelengths λ within the distance of the optical path difference (hole depth h) can be expressed as (2h / λ), and the phase can be obtained by multiplying by 2π as in Equation (1). In the equation, a(λ) and b(λ) represent the phenomenon that different substances have different reflectivities for different spectral wavelengths, and a(λ) can represent the background light intensity.

[0034]

Number

[0035] After replacing the phase parameter in the sine wave term of Equation (1) with the wave number k, Equation (2) is obtained. Equation (2) represents a function that can represent the first distribution data.

[0036]

Number

[0037] After going through the phase extraction process of Equation (2), the distribution relationship between the phase and the wave number as shown in Figure 5 can be obtained. The diagonal straight line in Figure 5 can be expressed by the following Equation (3), where P is the phase.

[0038]

Number

[0039] Equation (3) represents a function that can represent the second distribution data. Since the slope of Equation (3) is "2h", half of the slope of this diagonal straight line is the hole depth h of the hole structure. The measurement unit of the wavelength in Equation (1) (e.g., nanometer) becomes the measurement unit of the hole depth h. Thus, the hole depth of the hole structure can be determined.

[0040] Regarding the phase extraction process, there are many methods to extract the phase information from Equation (2) and convert the first distribution data into the second distribution data, which is the distribution relationship between the phase and the wave number.

[0041] In some embodiments, the Hilbert Transform can be used. Since Equation (2) is a cosine function, a sine function with a 90-degree phase shift can be obtained through the Hilbert Transform. Furthermore, when taking the arctangent function of the real part term of the cosine function and the imaginary part term of the sine function, the second distribution data can be obtained.

[0042] JPEG2025087623000005.jpg54166

[0043]

Number

[0044] Based on Equations (4) and (5), the function of the analytic signal S a (k) is as shown in Equation (6). The analytic signal S a (k) represents the distribution function between the wave number and the signal value. The operations required for the phase extraction of the analytic signal S a (k) are as shown in Equation (7). By dividing the real part term and the imaginary part term of the analytic signal S a (k) respectively and taking the arctangent function, it is used to obtain the phase value corresponding to the corresponding wave number k. In this way, based on the relational expression where φ is (2kh + φ 0 ), the distribution relationship between each wave number k as the second distribution data and the corresponding phase value is obtained (similar to Figure 5), which is an oblique straight line. Half of the slope of this oblique straight line (i.e., 2h) is the hole depth h of the hole structure.

[0045]

Number

[0046] In some other embodiments, the phase extraction process can obtain the distribution relationship between the phase and the wave number through the Fourier transform. Specifically, in the phase extraction process of this embodiment, first, Equation (2) can be converted into Euler's formula to obtain the function of Equation (8).

[0047]

Number

[0048] JPEG2025087623000009.jpg75168

[0049]

Number

[0050] As shown in the spectrogram after the processing of FIG. 8, one of the non-conjugate term and the conjugate term is retained and the rest is deleted. That is, only the waveform represented by the non-conjugate term or the conjugate term (see FIGS. 7 and 8) is retained, and the deleted part is filled with complex data points whose power density is a fixed value (e.g., 0), and the overall data length is maintained for the accurate calculation of the subsequent phase information. Taking the deletion of the conjugate term as an example, Equation (9) results in Equation (10) after performing the inverse Fourier transform.

[0051]

Number

[0052] Equation (10) can be used to obtain the phase corresponding to each frequency k and form a distribution relationship as the second distribution data. By performing phase processing on Equation (10), a straight line similar to that shown in FIG. 5 (the relational expression between the phase and the frequency, and the function is φ(k)=(φ 0 +2kh) is obtained, which becomes an oblique straight line, and half of the slope of this oblique straight line (i.e., 2h) is the hole depth h of the hole structure. In terms of the use of the arithmetic formula (the use of the command imag), it can be shown by the following Equation (11).

[0053]

Number

[0054] In some other embodiments, the phase extraction process can directly obtain a corresponding function by curve fitting based on the first distribution data, and can further obtain second distribution data representing the distribution relationship between the phase and the wave number based on a known function and each corresponding parameter. Many algorithms can implement the operation of curve fitting. For example, but not limited to this, the Levenberg-Marquardt method (LM method) is one of them.

[0055] Specifically, by performing curve fitting on the first distribution data, a function (a function that can draw the first distribution data, that is, Equation (2)) can be directly obtained. In addition to directly obtaining the hole depth h of the hole structure from within the function, the distribution relationship between the wave number and the corresponding phase required in the phase extraction process can also be obtained for comparison and inspection.

[0056] In the embodiments of the present invention, the hole depth of the hole structure is obtained from the relationship between the phase and the wave number. However, because the correlation information between the phase and the wave number is used, compared with the method of obtaining the hole depth with the frequency as the main parameter, the method of obtaining the hole depth based on the correlation information between the phase and the wave number has higher resolution.

[0057] When using a spectral interferometer, the detection light irradiated on the object to be detected has the characteristic that the wavelength changes within one section, and the formed synthetic wavelength can be expressed by Equation (20), where λ max is the longest wavelength within the section, and λ min is the shortest wavelength within the section.

[0058]

Number

[0059] In the method of estimating scale information (such as height, depth, etc.) based on the change characteristics due to the optical path difference, the minimum observable change is δh (i.e., the resolution). In addition, in the method of estimating scale information by determining the degree of phase shift using the peak value of the Fourier-transformed spectrogram, the peak value of the spectrogram can represent the number of periods of the optical interference fringes. The degree of phase shift is related to the number of periods of the sine-wave interference pattern. Since the length of each period is 2π, the product of the number of periods and 2π is the total phase shift. In this method, the calculation formula for the resolution δh is as shown in Equation (21), and in this operation, the total phase shift δφ is approximately 2π.

[0060] [Number]

[0061] On the other hand, as a comparison, this is also based on Fourier transform, but instead uses phase and wave number information, and is a method related to the conjugate term (i.e., only one of the real part term or the imaginary part term is retained). In this method using phase information, the degree of phase shift changes with the optical path difference, and the total phase shift δφ is shown as in Equation (22), where N represents the number of fringe periods (integer part) within the interference fringes, ε represents the remaining part (fractional part) of the interference fringe pattern, and F represents the number of imaging frames.

[0062] [Number]

[0063] The calculation formula for the resolution δh is shown in Equation (23).

[0064] [Number]

[0065] Thus, as an example, assume a wavelength range of 450 nm to 900 nm, 900 imaging frames, and an actual depth dimension of 202.3 μm.

[0066] In the case of the method for obtaining the hole depth with the frequency as the main parameter, the resolution algorithm is represented by Equation (24).

[0067] [Number]

[0068] In the case of the method related to the conjugate term using the phase and wave number information, the resolution algorithm is represented by Equation (25).

[0069] [Number]

[0070] As can be seen from the calculation results of Equation (24) and Equation (25), in the case of the method for obtaining the hole depth information using the correlation between the phase and the wave number in the embodiments of the present invention, compared with the method of determining the degree of phase shift based only on the peak value of the spectrogram after Fourier transform, the resolution obtained in the embodiments of the present invention is improved by nearly 2.5 times, and it is clearly possible to effectively improve the accuracy of the dimension of the hole depth.

[0071] Next, FIG. 9 is a schematic diagram of a hole structure provided with an oxide layer. When the surface around the hole structure 300 has the light-transmissive thin film oxide layer 310, the incident light forms not only the first reflected light R1 on the surface around the hole structure 300 and the second reflected light R2 on the bottom of the hole of the hole structure 300, but also the third reflected light R3 on the top surface of the oxide layer 310.

[0072] The information of the reflected light can be captured by the optical interference measurement device 100 shown in FIG. 2, and based on the interference phenomenon between these reflected lights and the corresponding period shown, it can also be used as the basis for determining the information of the hole depth h and the thickness d of the oxide layer.

[0073] Referring to FIG. 10, it is a graph showing the relationship between the reflected light intensity and the wave number of a hole structure provided with an oxide layer. The waveform with a low frequency and a large amplitude shown in the figure is the light intensity distribution of the interference light formed by the first reflected light R1 and the third reflected light R3, and this distribution relationship directly corresponds to the information on the thickness d of the oxide layer. On the other hand, the waveform with a high frequency and a small amplitude shown in the figure is the light intensity distribution of the interference light formed by the second reflected light R2 and the third reflected light R3, and this distribution relationship does not directly correspond to the hole depth h. The waveform with a high frequency and a small amplitude is a waveform with the waveform having a low frequency and a large amplitude as a carrier wave.

[0074] In an embodiment having a light-transmissive oxide layer 310 on the surface around the hole structure 300, the relationship between the phase and the wave number of the interference light formed by the first reflected light R1 and the third reflected light R3 can be expressed as the following formula (26) based on the Fresnel equations. In the formula, φ 2 is the phase of the interference light formed by the first reflected light R1 and the third reflected light R3. N 1 (k) is the refractive index of the oxide layer that changes with the change in the wave number (that is, due to the difference in the wavelength of the incident light, the refractive index passing through is also different). φ nonlinear is the non-linear term of this thin film oxide layer.

[0075]

Equation

[0076] Also, the relationship between the phase and the wave number of the interference light formed by the second reflected light R2 and the third reflected light R3 can be expressed as the following formula (27). In the formula, φ 1 is the phase of the interference light formed by the second reflected light R2 and the third reflected light R3. φ 0 is the DC term.

[0077] From the relationship between the reflected light intensity and the wave number (first distribution data) shown in FIG. 10, the second distribution data between the phase and the wave number can be obtained through a phase extraction process (using the curve fitting method in this embodiment). Here, φ 1The function fitted is as shown in Equation (28), φ 2 The function fitted by fitting is as shown in Equation (29).

[0078]

Number

[0079] Referring to FIG. 11, it is a graph showing the relationship between the phase and the wave number in the embodiment of FIG. 10. Among the two straight lines in FIG. 11, straight line L1 represents Equation (28), and straight line L2 represents Equation (29), showing the relationship between the phase and the wave number. The thickness d of the oxide layer of the thin film oxide layer 310 can be directly obtained based on the slope value of the straight line L2. As can be seen from Equation (29), half of the slope value of the straight line L2 is the thickness information of the oxide layer 310.

[0080] On the other hand, as can be seen from Equation (27) and Equation (28), the slope value obtained by Equation (28) includes the related information of the hole depth h and the thickness d of the oxide layer. Since the hole depth h is much larger than the thickness d of the oxide layer, the slope value obtained by Equation (28) is essentially larger than the slope value obtained by Equation (29). That is, there are two straight lines in the second distribution data in FIG. 11, and the slope value of the straight line with the larger slope among the two straight lines includes the information of the hole depth h and the thickness d of the oxide layer. The slope value of the straight line with the smaller slope among the two straight lines is the information of the thickness d of the oxide layer.

[0081] Furthermore, as can also be seen from Equation (27) and Equation (28), the slope value obtained by Equation (28) is not just the h information, but N 1 (k)d subtracted separately. Thus, to obtain the accurate information of the hole depth h, it is necessary to add back the subtracted information, that is, it becomes the calculation formula shown in Equation (30).

[0082]

Number

[0083] Therefore, if the slope value obtained from Equation (28) and the slope value obtained from Equation (29) are added and divided by 2, the hole depth h can be obtained. Accordingly, when the surface around the hole structure 300 has the light-transmissive oxide layer 310, the phase data in the first distribution data can indicate the phase information due to the hole depth and the phase information due to the thin film, and two straight lines can be shown in the second distribution data. Among the two straight lines, the slope value of the one with the larger slope is the first value, and the slope value of the one with the smaller slope among the two straight lines is the second value. Half of the second value is the thickness d of the oxide layer of the thin film oxide layer 310, and half of the sum of the first value and the second value is the hole depth h of the hole structure 300. The wavelength unit of the reflection spectrum is the measurement unit of the hole depth h and the thickness d of the oxide layer.

[0084] Accordingly, if the second distribution data shown between the phase and the wave number is obtained, the hole depth h and the thickness d of the oxide layer can be determined. Therefore, other mathematical processing procedures capable of obtaining the distribution relationship (second distribution data) between the phase and the wave number from the relationship between the reflected light intensity and the wave number (first distribution data) are also applicable. For example, since the relationship between the reflected light intensity and the wave number (first distribution data) shows the corresponding distribution relationship associated with the hole depth or the film thickness on different periods, first, by filtering a part of the signal, the corresponding straight lines (distribution relationship between the phase and the wave number) can be obtained one by one. When the two straight lines are combined, a distribution relationship diagram as shown in FIG. 11 is also shown and used for the calculation of the hole depth h and the thickness d of the oxide layer described above.

[0085] The various functions and operations described above executed in the form of software can be realized after storing the computer program in a non-volatile computer-readable storage medium and executing it. The computer program is stored in the medium and includes a plurality of commands for causing an electronic device (e.g., the arithmetic processing unit 200 described above, or various computer devices, network devices, or other electronic devices, etc.) or a processor to execute the hole depth measurement method using the phase extraction information of the reflection spectrum described in each embodiment of the present invention.

[0086] In short, based on the relationship between the reflected light intensity and the wave number, the relationship between the phase and the wave number is obtained through conversion, and then a linear distribution relationship can be shown. By calculating the slope value, the hole depth h information of the hole structure 300 can be obtained, and further the thickness d information of the oxide layer can also be obtained. This not only increases the measurement resolution but also improves the accuracy.

[0087] The present invention has disclosed the best embodiment above. However, as can be understood by those skilled in the art, this embodiment is only used to explain the present invention and should not be understood as limiting the scope of the present invention. It should be noted that all changes and substitutions having the same effect as this embodiment are included within the scope of the present invention. Therefore, the protection scope of the present invention shall be in accordance with the definition of the claims.

Explanation of Reference Numerals

[0088] 100 Optical interference measurement device 101 Illumination light 110 Imaging unit 120 Light source unit 130 Spectroscopy unit 200 Arithmetic processing unit 300 Hole structure 310 Oxide layer d Thickness of oxide layer h Hole depth L1 Straight line L2 Straight line R1 First reflected light R2 Second reflected light R3 Third reflected light S110~S140 Steps x Object to be measured

Claims

1. obtaining a reflectance spectrum from a target area having high aspect ratio hole structures; obtaining first distribution data between reflected light intensity and wave number based on the reflection spectrum; converting the first distribution data into second distribution data between phase and the wavenumber through a phase extraction process; determining a hole depth of the hole structure and a wavelength unit of the reflection spectrum as a measurement unit of the hole depth based on a slope value of at least one straight line represented by the second distribution data; A hole depth measurement method using phase extraction information of a reflection spectrum, comprising:

2. The method of claim 1 , wherein when the second distribution data shows a single straight line, half of the slope value of the line is the pore depth of the pore structure.

3. The phase extraction process comprises: removing DC terms in the first distribution data; performing a Hilbert transform to obtain an analytic signal having a real term in the form of a cosine and an imaginary term in the form of a sine; obtaining a distribution relationship between phase and wave number as second distribution data based on an arctangent function of the real part term and the imaginary part term; The method of claim 1 , comprising:

4. The phase extraction process comprises: converting the first distribution data into intermediate conversion data having the real part term and the imaginary part term; performing a Fourier transform; performing a point deleting and padding step of keeping only one of the real terms or the imaginary terms and deleting the other data and padding complex data points with fixed power density to maintain data length; performing an inverse Fourier transform; obtaining a distribution relationship between the phase and the wave number as the second distribution data; The method of claim 1 , comprising:

5. The method according to any one of claims 1 to 4, wherein, when a peripheral surface of the hole structure has a light-transmitting oxide layer, the phase data in the first distribution data defines a hole depth phase and a thin film phase, and the second distribution data shows two straight lines, a slope value of the line with a larger slope of the two straight lines is a first value, a slope value of the line with a smaller slope of the two straight lines is a second value, half of the second value is the thickness of the oxide layer, half of the sum of the first value and the second value is the hole depth of the hole structure, and a wavelength unit of the reflection spectrum is a measurement unit of the thickness of the oxide layer.

6. A non-volatile computer readable storage medium storing a computer program for loading into a processing unit to cause said processing unit to carry out the method according to any one of claims 1 to 4.

7. A non-volatile computer readable storage medium storing a computer program for loading into a processing unit to cause said processing unit to carry out the method of claim 5.

8. an optical interference measurement device for obtaining a reflectance spectrum from the target area; A processor coupled to the optical interference measuring device for carrying out the method according to any one of claims 1 to 4. A hole depth measurement system using phase extraction information of a reflection spectrum, comprising:

9. The measurement system of claim 8 , wherein the optical interferometer is controlled such that one scanning measurement operation is performed only on a single hole structure within the target area.

10. an optical interference measurement device for obtaining a reflectance spectrum from the target area; A processor coupled to the optical interference measuring device for carrying out the method according to claim 5. A hole depth measurement system using phase extraction information of a reflection spectrum, comprising:

11. The measurement system of claim 10 , wherein the optical interferometer is controlled such that one scanning measurement operation is performed only on a single hole structure within the target area.

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