Hole depth measurement method, measurement system, and computer-readable medium using phase extraction information of reflection spectra

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 improve the space utilization rate and solve 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 the bare chip stacking method.

[0003] In these stacked structures, through the Through Silicon Via (TSV) technology, signals of different chips are connected to each other, the space utilization rate is improved, and the conduction distance is also shortened, so that the improvement of the signal and power transmission speed can be achieved.

[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 in the present invention, accuracy is improved by increasing the measurement resolution of the hole depth.

[0007] According to some embodiments, the present invention provides a hole depth measurement method using phase-extracted information of a reflection spectrum, comprising the steps of: obtaining a reflection spectrum from a target region having a hole structure with a high aspect ratio; obtaining first distribution data between reflected light intensity and wavenumber based on the reflection spectrum; converting the first distribution data into second distribution data between phase and wavenumber through a phase extraction process; and determining the hole depth of the hole structure and the wavelength unit of the reflection spectrum as a unit of measurement for the hole depth based on the slope value of at least one straight line shown by the second distribution data.

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

[0009] According to some embodiments, the phase extraction process may include removing the DC term in the first distribution data, performing a Hilbert transform to obtain an analytical 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 phase and wavenumber as second distribution data based on the inverse tangent functions 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 transformed data having real and imaginary terms; performing a Fourier transform; performing a point deletion and filling step of retaining only one of the real or imaginary terms, deleting the other data, and filling in complex data points with a fixed power density to maintain the data length; performing an inverse Fourier transform; and obtaining a distribution relationship between phase and wavenumber as second distribution data.

[0011] According to some embodiments, when the surrounding surface of the hole structure has a light-permeable oxide layer, the phase data in the first distribution data can define the hole depth phase and the 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 is the first value, and the slope value of the straight line with the smaller slope is the 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 unit of measurement for 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 can be used to load into an arithmetic processing unit and to cause the arithmetic processing unit to perform the methods described above.

[0013] According to some embodiments, the present invention further provides a hole depth measurement system using phase extraction information of a reflectance spectrum, comprising an optical interferometry device and a computing device. The optical interferometry device can be used to obtain a reflectance spectrum from a target region. The computing device can be coupled to the optical interferometry device and used to perform the method described above. [Effects of the Invention]

[0014] Therefore, based on the relationship between reflected light intensity and wavenumber, a distribution relationship between phase and wavenumber is obtained through a transformation, followed by a linear distribution relationship. By calculating the slope value, hole depth information of the hole structure can be obtained, and further, information on the thickness of the oxide layer can also be obtained. This allows for increased measurement resolution and improved accuracy. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram of the hole structure. [Figure 2] This is a schematic diagram of a measurement system according to several embodiments. [Figure 3] A flowchart of a hole depth measurement method using phase extraction information of a reflection spectrum according to some embodiments. [Figure 4] A graph showing the relationship between reflected light intensity and wave number according to some embodiments. [Figure 5] A graph showing the relationship between phase and wave number in the embodiment of FIG. 4. [Figure 6] A graph showing the relationship between the reflected light intensity from which the DC term is removed and the wave number according to some embodiments. [Figure 7] A spectrogram of the first distribution data after Fourier transform according to some embodiments. [Figure 8] A processed spectrogram of the embodiment of FIG. 7. [Figure 9] A schematic diagram of a hole structure having an oxide layer. [Figure 10] A graph showing the relationship between the reflected light intensity and the wave number of a hole structure having an oxide layer. [Figure 11] A graph showing the relationship between phase and wave number in the embodiment of FIG. 10.

BEST MODE FOR CARRYING OUT THE INVENTION

[0016] In order 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" 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 these elements listed in this specification, and although not explicitly described, may include other elements commonly inherent to a unit, component, structure, device, module, system, part, or region.

[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. In some cases or configurations, it should be understood that the ordinal terms can be used interchangeably without affecting the implementation of the present invention.

[0020] Figure 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] Figure 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 at a time or one area at a time). When the illumination light is irradiated on 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] The coaxial illumination configuration of the light source unit 120 and the spectral unit 130 allows reflected light from the hole structure 300 to 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 interference phenomena from the object being measured having the hole structure 300. The processing unit 200 is coupled to the light source unit 120 and the imaging unit 110 of the optical interferometry device 100, performs scanning operations, receives the spectral signal, and then executes subsequent processing steps such as phase extraction.

[0023] The configuration of the optical interferometry device 100 in Figure 2 is merely an example; any optical interferometry device, such as a spectral interferometer or other type of interferometer, in other words, a measuring device that obtains reflected light from a reference surface (surface) of an object under measurement and reflected light from the bottom of a hole structure, and obtains the optical interference phenomenon between the two, can be applied to embodiments of the present invention. The arithmetic processing unit 200 may be a single computer, multiple computers, or a single or multiple arithmetic processing modules configured within the entire measurement system. The arithmetic processing unit 200 is used to receive and process the spectral signal of the reflected light provided by the optical interferometry device 100.

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

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

[0026] Step S110: Step to acquire the reflectance spectrum. This step involves acquiring the reflectance spectrum from a target region. The target region has a high aspect ratio hole structure. The target region may have only a single hole structure or may have multiple hole structures.

[0027] Step S120: A step to obtain the correlation between reflected light intensity and wavenumber. This step obtains first distribution data that can represent the correlation between light intensity and wavenumber by converting the reflected light spectrum into a distribution relationship that can show the correlation between reflected light intensity and wavenumber.

[0028] Step S130: Phase extraction step. In this step, the first distribution data is transformed into a distribution relationship that can show the correlation between phase and wavenumber by a phase extraction process, and a second distribution data is obtained that can represent the correlation between phase and wavenumber.

[0029] Step S140: Hole depth determination step. This step determines the hole depth of the hole structure based on the slope value of at least one straight line that can be shown by the second distribution data. The wavelength units of the reflection spectrum are used as the unit of measurement for hole depth.

[0030] Light has sinusoidal characteristics, and different reflected light from the surrounding surface of a hole structure (e.g., the top of the hole) and the bottom of the hole structure can cause a redistribution of light intensity in space based on the optical path difference, forming an interference phenomenon. By extracting phase information from the reflection spectrum, the distribution relationship between phase and wavenumber can be obtained, and this distribution relationship can be used to obtain information about the depth of the hole structure. Furthermore, this can effectively improve resolution.

[0031] In some embodiments, step S120 can determine the corresponding light intensity value based on wavenumbers of the same interval. Thus, when the wavelengths in the reflection spectrum data are converted to wavenumbers, the interpolated values ​​of the corresponding light intensity values ​​can be determined by a general interpolation method or other means.

[0032] Next, Figure 4 is a graph showing the relationship between reflected light intensity and wavenumber in several embodiments. The wavenumber is the number of wavelengths per unit length 2π, or the number of wave repetitions per unit length 2π. If the wavenumber is defined as k, then k = 2π / λ.

[0033] If there is interference in the reflection spectrum based on the optical path difference, the optical path difference is twice the hole depth (it moves an additional distance h during incidence and reflection). The number of wavelengths λ within the optical path difference distance (hole depth h) can be expressed as (2h / λ), and the phase can be found by multiplying by 2π as in equation (1). In the equation, a(λ) and b(λ) represent the phenomenon where different materials exhibit different reflectances for different spectral wavelengths, and a(λ) can represent the background light intensity.

[0034]

number

[0035] Equation (2) is obtained by replacing the phase parameter in the sinusoidal term of equation (1) with the wavenumber k. 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 phase and wavenumber shown in Figure 5 can be obtained. The diagonal 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 show the second distribution data. The slope of equation (3) is "2h", so half the slope of this diagonal line is the hole depth h of the hole structure. The unit of measurement for the wavelength in equation (1) (e.g., nanometers) becomes the unit of measurement for the hole depth h. This allows the hole depth of the hole structure to be determined.

[0040] Regarding the phase extraction process, there are many methods for extracting phase information from equation (2) and converting the first distribution data into second distribution data, which represents the distribution relationship between phase and wavenumber.

[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 is obtained via the Hilbert Transform, and by taking the arctangent function of the real part of the cosine function and the imaginary part of the sine function, the second distribution data can be obtained.

[0042] JPEG0007840387000004.jpg54166

[0043]

number

[0044] Analysis signal S based on equations (4) and (5) a The function of (k) is given by equation (6). Analyzed signal S a (k) represents the distribution function between wavenumber and signal value. Analyzed signal S a The calculation required for phase extraction of (k) is as shown in equation (7), and the analysis signal S a The real and imaginary terms of (k) are divided to obtain the arctangent function, which is used to find the phase value corresponding to the corresponding wave number k. In this way, based on the relationship φ = (2kh + φ0), the distribution relationship between each wave number k as second distribution data and the corresponding phase value is obtained (similar to Figure 5), which is a diagonal line, and half of the slope of this diagonal 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 phase and wavenumber through the Fourier transform. Specifically, in the phase extraction process of this embodiment, equation (2) is first transformed into Euler's formula to obtain the function of equation (8).

[0047]

number

[0048] JPEG0007840387000008.jpg75168

[0049]

number

[0050] As shown in the processed spectrogram of Figure 8, one of the non-conjugate and conjugate terms is retained, and the other is deleted. In other words, only the waveform represented by the non-conjugate or conjugate term (see Figures 7 and 8) is retained, and the deleted portion is filled with complex data points with a fixed power density (e.g., 0), so that the overall data length is maintained for accurate calculation of subsequent phase information. Taking the deletion of the conjugate term as an example, equation (9) becomes equation (10) after undergoing the inverse Fourier transform.

[0051]

number

[0052] Equation (10) can be used to determine the phase corresponding to each wavenumber k and to form a distribution relationship as second distribution data. By applying phase processing to equation (10), a straight line similar to that shown in Figure 5 (a relationship between phase and wavenumber, with the function φ(k)=(φ0+2kh)) is obtained, which is a diagonal line, and half of the slope of this diagonal line (i.e., 2h) is the hole depth h of the hole structure. In terms of the use of the calculation formula (using the command imag), this can be shown by the following equation (11).

[0053]

number

[0054] In some other embodiments, the phase extraction process can directly determine the corresponding function by curve fitting based on the first distribution data, and can also obtain second distribution data representing the distribution relationship between phase and wavenumber based on the known function and its corresponding parameters. Curve fitting can be performed by many algorithms, but is not limited to these; the Levenberg-Marquardt method (LM) is one such example.

[0055] Specifically, by curve fitting the first distribution data, we can directly obtain a function (a function that can plot the first distribution data, i.e., equation (2)), and from within this function, we can directly determine the hole depth h of the hole structure. Furthermore, for comparison and inspection purposes, we can also obtain the distribution relationship between the wavenumber and the corresponding phase required in the phase extraction process.

[0056] In the embodiments of the present invention, the hole depth of the hole structure is determined from the relationship between phase and wavenumber. Because it uses correlation information between phase and wavenumber, the method of determining the hole depth based on the correlation information between phase and wavenumber has higher resolution compared to the method of determining the hole depth using frequency as the main parameter.

[0057] When using a spectral interferometer, the detection light irradiated onto the object to be detected has the characteristic of changing wavelength within a single interval, and the resulting composite wavelength can be expressed by equation (20), where λ max λ is the longest wavelength within the interval. min This is the shortest wavelength within the interval.

[0058]

number

[0059] In methods that estimate scale information (height, depth, etc.) based on the change characteristics due to optical path difference, the smallest observable change is δh (i.e., resolution). In methods that estimate 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 sinusoidal interference pattern. Since the length of each period is 2π, the product of the number of periods and 2π is the total phase shift, and in this method, the formula for calculating the resolution δh is as shown in equation (21), and in this calculation, the total phase shift δφ is approximately 2π.

[0060]

number

[0061] On the other hand, as a contrast, there is a method that is also based on the Fourier transform, but instead uses phase and wavenumber information and relates to the conjugate term (i.e., only one of the real or imaginary part is preserved). In this method that uses phase information, the degree of phase shift changes with the optical path difference, and the total phase shift δφ is given by equation (22), where N is the number of fringe periods in the interference fringe (integer part), ε is the remaining part of the interference fringe pattern (fractional part), and F is the number of imaging frames.

[0062]

number

[0063] The formula for calculating the resolution δh is given by equation (23).

[0064]

number

[0065] As an example, the wavelength range is set to 450 nm to 900 nm, the number of imaging frames to 900, and the actual depth dimension to 202.3 μm.

[0066] In the method for determining hole depth using frequency as the primary parameter, the resolution algorithm is expressed by equation (24).

[0067]

number

[0068] For methods that use phase and wavenumber information and involve conjugate terms, the resolution algorithm is expressed by equation (25).

[0069]

number

[0070] As can be seen from the calculation results of equations (24) and (25), in the method of obtaining hole depth information using the correlation between phase and wavenumber in the embodiment of the present invention, the resolution obtained in the embodiment of the present invention is improved by nearly 2.5 times compared to the method of determining the degree of phase shift based only on the peak value of the spectrogram after the Fourier transform, and it is clear that the accuracy of the hole depth dimension can be effectively improved.

[0071] Next, Figure 9 is a schematic diagram of a hole structure with an oxide layer. When a light-transmitting thin film oxide layer 310 is present on the surface surrounding the hole structure 300, incident light not only forms a first reflected light R1 on the surface surrounding the hole structure 300 and a second reflected light R2 at the bottom of the hole in the hole structure 300, but can also form a third reflected light R3 on the top surface of the oxide layer 310.

[0072] The reflected light information can be captured by the optical interferometry device 100 shown in Figure 2, and the interference phenomena between these reflected lights and the corresponding periods shown can be used as the basis for determining the hole depth h and the thickness d of the oxide layer.

[0073] Referring to Figure 10, this graph shows the relationship between reflected light intensity and wavenumber for a hole structure with an oxide layer. The low-frequency, high-amplitude waveform shown in the figure represents the light intensity distribution of interference light formed by the first reflected light R1 and the third reflected light R3, and this distribution relationship directly corresponds to the information about the thickness d of the oxide layer. On the other hand, the high-frequency, low-amplitude waveform shown in the figure represents the light intensity distribution of 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 high-frequency, low-amplitude waveform is a waveform with the low-frequency, high-amplitude waveform as the carrier wave.

[0074] In an embodiment in which a light-permeable oxide layer 310 is present on the surface surrounding the hole structure 300, the relationship between the phase and wavenumber of the interference light formed by the first reflected light R1 and the third reflected light R3 can be expressed as follows, based on Fresnel's equations: (26). In the equation, φ2 is the phase of the interference light formed by the first reflected light R1 and the third reflected light R3. N1(k) is the refractive index of the oxide layer that changes with the wavenumber (i.e., the refractive index that passes through differs depending on the wavelength of the incident light). nonlinear This is the nonlinear term of this thin film oxide layer.

[0075]

number

[0076] Furthermore, the relationship between the phase and wavenumber of the interference light formed by the second reflected light R2 and the third reflected light R3 can be expressed as shown in equation (27) below. In the equation, φ1 is the phase of the interference light formed by the second reflected light R2 and the third reflected light R3. φ0 is the DC term.

[0077] From the relationship between reflected light intensity and wavenumber (first distribution data) shown in Figure 10, a second distribution data between phase and wavenumber can be obtained through a phase extraction process (in this embodiment, a curve fitting method is used). Here, the function fitted with φ1 is as shown in equation (28), and the function fitted with φ2 is as shown in equation (29).

[0078]

number

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

[0080] On the other hand, as can be seen from equations (27) and (28), the slope value obtained from equation (28) includes related information about 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 from equation (28) is essentially larger than the slope value obtained from equation (29). In other words, there are two straight lines in the second distribution data in Figure 11, and the slope value of the line with the larger slope of the two lines includes information about the hole depth h and the thickness d of the oxide layer. The slope value of the line with the smaller slope of the two lines contains information about the thickness d of the oxide layer.

[0081] Furthermore, as can be seen from equations (27) and (28), the slope value obtained by equation (28) is not simply h information, but rather the value obtained by subtracting N1(k)d separately. Therefore, in order to obtain accurate hole depth h information, it is necessary to add back the subtracted information, which results in the calculation formula shown in equation (30).

[0082]

number

[0083] Therefore, the hole depth h can be determined by adding the slope value obtained from equation (28) and the slope value obtained from equation (29) and dividing by 2. Thus, when a light-transmitting oxide layer 310 is present on the surface surrounding the hole structure 300, the phase data in the first distribution data can show phase information due to the hole depth and phase information due to the thin film, and two straight lines can be shown in the second distribution data. The slope value of the straight line with the larger slope is the first value, and the slope value of the straight line with the smaller slope 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 and second values ​​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] As a result, if a second distribution data showing the relationship between phase and wavenumber is obtained, the hole depth h and the thickness d of the oxide layer can be determined. Therefore, other mathematical processing procedures that can obtain the distribution relationship between phase and wavenumber (second distribution data) from the relationship between reflected light intensity and wavenumber (first distribution data) are also applicable. For example, since the relationship between reflected light intensity and wavenumber (first distribution data) shows corresponding distribution relationships associated with hole depth or film thickness on different periods, by first filtering a part of the signal, one corresponding line (distribution relationship between phase and wavenumber) can be obtained at a time, and by combining the two lines, a distribution relationship diagram as shown in Figure 11 is also shown, which is used for the calculation of the hole depth h and the thickness d of the oxide layer as described above.

[0085] The various functions and calculations described above, which are performed in software form, can be realized after storing and executing a computer program on a non-volatile computer-readable storage medium. The computer program is stored on the medium and includes a number of commands that cause an electronic device (e.g., the aforementioned processing unit 200, or various computer equipment, network equipment, or other electronic equipment) or processor to perform a 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 reflected light intensity and wavenumber, the relationship between phase and wavenumber can be obtained through a transformation, and then a linear distribution relationship can be shown. By calculating the slope value, information on the hole depth h of the hole structure 300 can be obtained, and further information on the oxide layer thickness d can also be obtained. Not only is the resolution of the measurement increased, but the accuracy can also be improved.

[0087] Although the present invention has disclosed best embodiments above, as those skilled in the art will understand, these embodiments are used solely for illustrative purposes and should not be understood as limiting the scope of the invention. It should be noted that all modifications and substitutions having equivalent effects to those in these embodiments are included within the scope of the invention. Therefore, the scope of protection of the present invention is as defined in the claims. [Explanation of symbols]

[0088] 100 Optical Interferometry Device 101 Illumination light 110 Imaging Unit 120 light source units 130 Spectroscopic Unit 200 Arithmetic Processing Unit 300 hole structure 310 Oxide layer d. Oxide layer thickness h Hole depth L1 straight line L2 straight line R1 1st reflected light R2 2nd reflected light R3 3rd reflected light S110~S140 Step x Object to be measured

Claims

1. The steps include obtaining a reflection spectrum from a target region having a high aspect ratio hole structure, The steps include obtaining first distribution data between reflected light intensity and wavenumber based on the aforementioned reflection spectrum, The steps include converting the first distribution data into a second distribution data between the phase and the wavenumber through a phase extraction process, A step of determining the hole depth of the hole structure and the wavelength unit of the reflection spectrum as the unit of measurement for the hole depth based on the slope value of at least one straight line shown by the second distribution data. A hole depth measurement method using phase extraction information from the reflection spectrum, including [specific data].

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

3. The phase extraction process described above is Removing the DC term from the first distribution data, This involves transforming the signal into a Hilbert transform, performing the 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, Based on the inverse tangent functions of the real and imaginary terms, the distribution relationship between phase and wavenumber as second distribution data is obtained. The method according to claim 1, including the method described in the preceding claim.

4. The phase extraction process described above is The first distribution data is transformed into intermediate transformed data having a real term and an imaginary term, Performing a Fourier transform, The process involves retaining only one of the terms in the real part or the imaginary part, deleting the other data, and performing a point deletion and filling step to fill in complex data points with a fixed power density in order to maintain the data length. Performing the inverse Fourier transform, To obtain the distribution relationship between the phase and the wavenumber as the second distribution data, The method according to claim 1, including the method described in claim 1.

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

6. A non-volatile computer-readable storage medium used for loading into a processing unit, which stores a computer program for causing the processing unit to perform the method according to any one of claims 1 to 4.

7. A non-volatile computer-readable storage medium used for loading into a processing unit, which stores a computer program for causing the processing unit to execute the method according to claim 5.

8. An optical interferometry device for obtaining the reflection spectrum from a target region, A processing unit coupled to the optical interferometer for performing the method described in any one of claims 1 to 4, A hole depth measurement system that uses phase extraction information from the reflection spectrum, including [specific data].

9. The measurement system according to claim 8, wherein the optical interferometry apparatus is controlled so that a single scanning measurement operation is performed only for a single hole structure within the target region.

10. An optical interferometry device for obtaining the reflection spectrum from a target region, A processing unit coupled to the optical interferometry device for performing the method described in claim 5, A hole depth measurement system that uses phase extraction information from the reflection spectrum, including [specific data].

11. The measurement system according to claim 10, wherein the optical interferometry apparatus is controlled so that a single scanning measurement operation is performed only for a single hole structure within the target region.

Images