Etching depth detection device, method and reaction processing equipment

Abstract

The present disclosure relates to the technical field of etching processing, and provides an etching depth detection device, method and reaction processing equipment, wherein the device comprises: a detection component, configured to output a detection signal and receive an echo signal reflected by the detection signal in the thin film layer of the sample; a processing unit, coupled to the detection component, for decomposing a set of target frequency components according to the echo signal, and obtaining the corresponding number of cycles based on the preset etching duration and the target frequency of each target frequency component; determining the amount of change of the thin film layer within a single cycle according to the target signal wavelength corresponding to each target frequency and the refractive index of the thin film layer, and obtaining the basic etching depth in combination with the corresponding number of cycles; obtaining the current etching depth based on the mathematical expectation of a set of basic etching depths. Thus, in the case of shallow etching and incomplete etching of the etching film layer, an accurate number of cycles can be obtained to calculate the accurate etching depth, so as to make accurate endpoint detection of the etching process.

Description

Technical Field

[0001] The present disclosure relates to the field of etching processing technology, and in particular to an etching depth detection device, method and reaction processing equipment. Background Art

[0002] In a typical plasma etching process, different process gas combinations (such as C x F y , O2, Ar, etc.) are excited by radio frequency to form plasma in a radio frequency environment. The formed plasma physically bombards and chemically reacts with the wafer surface under the action of the electric field of the upper and lower electrodes of the etching chamber, completing the processing of the wafer surface design pattern and key processes. Typical etching chambers include capacitively coupled chambers (CCP) and inductively coupled chambers (ICP).

[0003] During the etching process, endpoint detection is performed to monitor the etching process and stop etching at the etching endpoint to obtain a precise etching amount.

[0004] Common endpoint detection methods in the industry include optical emission spectroscopy and optical interferometry.

[0005] Optical emission spectroscopy (OES) is an analytical technique used to detect the composition of various metal elements. It is widely used and highly trusted. Samples that can be detected using OES technology include molten metal, semi-finished and finished metals, as well as metal processing, pipes, bolts, bars, wires, plates, etc. The electromagnetic spectrum used by OES includes the visible spectrum and part of the ultraviolet spectrum. The wavelength range is 130nm to 800nm. The ICP emission spectroscopy analysis process is mainly divided into three steps: excitation, spectroscopy and detection. 1) Use a plasma excitation light source to evaporate and vaporize the sample, dissociate or decompose it into an atomic state, and the atoms may further ionize into an ionic state. The atoms and ions are excited to emit light in the light source. 2) Use a spectrometer to decompose the light emitted by the light source into a spectrum arranged by wavelength. 3) Use a photoelectric device to detect the spectrum, and perform qualitative analysis of the sample according to the measured spectral wavelength, and quantitative analysis according to the intensity of the emitted light. However, optical emission spectroscopy will have a more obvious signal when the reaction process switches. The signal needs to be processed during actual use. The signal sensitivity is affected by many factors, including but not limited to the intensity of the light source, the sensitivity of the detector, and the concentration of the sample. In some cases, the sample concentration may be too low to obtain adequate signal.

[0006] The principle of optical interferometry for endpoint detection is based on the phenomenon of optical interference. Interference refers to the interaction between two or more waves when they are superimposed in space. In the optical interferometry method, the wave nature of light and the thin film interference phenomenon are used. When a beam of light is irradiated onto the surface of a thin film, part of the light will be reflected by the film surface, while the other part will pass through the film and reflect on its lower surface. The two parts of light have different optical paths and there is an optical path difference, and there will be interference effects between them, forming alternating light and dark interference fringes. The shape, size, and number of these fringes are affected by factors such as film thickness, incident and emission angles, and light wavelength. By observing the changes in these fringes, the thickness of the film can be inferred, and the corresponding etching amount can be obtained.

[0007] At present, there is a demand for shallow etching in the industry, which corresponds to etching a shallow thickness in the thin film layer. Because the thin film layer is not completely etched, optical emission spectroscopy cannot be used. Optical emission spectroscopy is applicable to the changes in the excitation spectrum during the conversion of the generated gas in the cavity into the reactive gas after the film layer is completely etched. There is no complete etching in this application, and the spectrum does not change. In addition, for shallow etching, the range of film thickness detection by optical interference method is usually a few microns to hundreds of microns. Limited by the selected observation band and the number of interference fringes, the more interference fringes, the more accurate the detection, and the fewer interference fringes, the farther the detected value deviates from the actual value. At present, the industry generally uses the method of counting the number of cycles (corresponding to the number of interference fringes) to calculate the film thickness, but for shallow etching, the number of cycles is small or even less than one cycle, resulting in the inability to count the correct number of cycles less than 1 using traditional optical interference method. Summary of the invention

[0008] In view of the above shortcomings of the related art, the purpose of the present disclosure is to provide an etching depth detection device, method and reaction processing equipment to solve the problems in the related art.

[0009] According to a first aspect of the present disclosure, there is provided an etching depth detection device, which is applied to a reaction processing device, wherein the reaction processing device comprises a reaction chamber; the etching depth detection device comprises: a detection component, which is configured to output a detection signal to a sample carrier surface in the reaction chamber, and receive an echo signal reflected by the detection signal in a thin film layer of the sample; the echo signal comprises an interference signal of reflection signals on different surfaces of the thin film layer; a processing unit, coupled to the detection component, for decomposing a group of target frequency components according to the echo signal, and dividing the period length corresponding to the target frequency of each target frequency component by a preset etching time to obtain a corresponding number of periods to form a group of period numbers, wherein each target frequency corresponds to a target signal wavelength; determining a change amount of the thin film layer within a single period according to the target signal wavelength corresponding to each target frequency and the refractive index of the thin film layer, and obtaining each basic etching depth according to the change amount of the thin film layer corresponding to each target frequency component in a group of target frequency components multiplied by the corresponding period number of the target frequency component in the group of period numbers to form a group of basic etching depths; and obtaining a current etching depth based on a mathematical expectation of a group of the basic etching depths.

[0010] In an embodiment of the first aspect, the detection signal is configured to be incident on the thin film layer at an angle perpendicular to the sample loading surface.

[0011] In an embodiment of the first aspect, obtaining a set of target frequency components based on the decomposition of the echo signal includes: excluding interference frequency components from the set of frequency components obtained based on the decomposition of the echo signal to obtain target frequency components; wherein the interference frequency components are consistent with the frequency of the radiation signal generated during the reaction process in the reaction chamber.

[0012] In an embodiment of the first aspect, a plasma for etching a sample is formed in the reaction chamber; the radiation signal includes at least one of the following: a light signal excited by a gas in the reaction chamber; a radiation signal generated by at least one state of the plasma in the reaction chamber: ionization, excitation, deexcitation, radiation transition, recombination, and charge exchange.

[0013] In an embodiment of the first aspect, the method of obtaining the current etching depth based on the mathematical expectation of a group of basic etching depths also includes: determining whether the difference between the group of basic etching depths meets a preset quality condition; in response to meeting the preset quality condition, obtaining the current etching depth based on the mathematical expectation of the group of basic etching depths; in response to not meeting the preset quality condition, performing noise reduction processing on the group of basic etching depths, and obtaining the current etching depth based on the mathematical expectation of the group of basic etching depths after the noise reduction processing.

[0014] In an embodiment of the first aspect, the difference is obtained by at least one of variance, standard deviation and goodness of fit; and / or the noise reduction processing includes at least one of the following: preprocessing, including at least one of smoothing, interpolation, and denoising; outlier detection and elimination.

[0015] In an embodiment of the first aspect, the processing unit is further configured to, in response to the current etching depth reaching an etching endpoint, cause the reaction processing device to stop etching.

[0016] According to a second aspect of the present disclosure, there is provided an etching depth detection method, which is applied to a reaction processing device, wherein the reaction processing device comprises a reaction chamber; the etching depth detection method comprises: obtaining a detection signal output to a sample carrier surface in the reaction chamber, and receiving an echo signal reflected by the detection signal; the echo signal comprises an interference signal between reflection signals of the detection signal on the upper and lower surfaces of a thin film layer of the sample; decomposing a group of target frequency components according to the echo signal, and dividing the period length corresponding to the target frequency of each target frequency component by a preset etching time to obtain a corresponding number of periods, thereby forming a group of period numbers, wherein each target frequency corresponds to a target signal wavelength; determining a change amount of the thin film layer within a single period according to the target signal wavelength corresponding to each target frequency and the refractive index of the thin film layer, and obtaining each basic etching depth according to the change amount of the thin film layer corresponding to each target frequency component in a group of target frequency components multiplied by the corresponding period number of the target frequency component in the group of period numbers, thereby forming a group of basic etching depths; and obtaining a current etching depth based on a mathematical expectation of a group of the basic etching depths.

[0017] In an embodiment of the second aspect, the decomposing the echo signal to obtain a set of target frequency components includes: excluding interference frequency components in the set of frequency components decomposed based on the echo signal to obtain target frequency components; wherein the interference frequency components are consistent with the frequency of the radiation signal generated during the reaction in the reaction chamber; and / or, obtaining the current etching depth based on the mathematical expectation of a set of basic etching depths, further includes: determining whether the difference between the group of basic etching depths meets a preset quality condition; in response to meeting the preset quality condition, obtaining the current etching depth based on the mathematical expectation of the group of basic etching depths; in response to not meeting the preset quality condition, performing noise reduction processing on the group of basic etching depths, and obtaining the current etching depth based on the mathematical expectation of the group of basic etching depths after the noise reduction processing.

[0018] A third aspect of the present disclosure provides a reaction processing device, comprising: a reaction chamber, comprising: a carrier having a sample carrying surface for carrying a sample; and an etching depth detection device as described in any one of the first aspects.

[0019] As described above, an etching depth detection device, method and reaction processing equipment are provided in the embodiments of the present disclosure, and the device includes: a detection component, which is configured to output a detection signal to the sample carrier surface in the reaction chamber, and receive an echo signal reflected by the detection signal in the thin film layer of the sample; the echo signal includes an interference signal of the reflection signal on different surfaces of the thin film layer; a processing unit, coupled to the detection component, is used to decompose the echo signal to obtain a group of target frequency components, and divide the preset etching time by the period length corresponding to the target frequency of each target frequency component to obtain the corresponding number of periods to form a group of period numbers, each target frequency corresponds to a target signal wavelength; determine the amount of change of the thin film layer within a single period according to the target signal wavelength corresponding to each target frequency and the refractive index of the thin film layer, and multiply the amount of change of the thin film layer corresponding to each target frequency component in a group of target frequency components by the corresponding number of periods of the target frequency component in the group of period numbers to obtain each basic etching depth to form a group of basic etching depths; and obtain the current etching depth based on the mathematical expectation of a group of the basic etching depths. Therefore, in the case of shallow etching and incomplete etching of the etched film layer, an accurate number of cycles can be obtained to calculate the accurate etching depth, so as to make an accurate endpoint detection for the etching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of a device for measuring etching endpoint using optical emission spectroscopy in one embodiment of the present disclosure is shown.

[0021] Figure 2 A schematic diagram of a spectral curve using optical emission spectroscopy in an embodiment of the present disclosure is shown.

[0022] Figure 3 A schematic diagram of a device for measuring an etching endpoint using optical interferometry in an embodiment of the present disclosure is shown.

[0023] Figure 4 A schematic diagram of a light path using the optical interferometry method in an embodiment of the present disclosure is shown.

[0024] Figure 5 A schematic diagram of a spectrum curve using the optical interferometry method in an embodiment of the present disclosure is shown.

[0025] Figure 6 A schematic diagram showing the structure of an etching depth detection device in one embodiment of the present disclosure is shown.

[0026] Figure 7 A schematic flow chart showing an etching depth detection method implemented by an etching depth detection device in one embodiment of the present disclosure.

[0027] Figure 8 A specific flow chart of step S703 in the etching depth detection method in one embodiment of the present disclosure is shown.

[0028] Fig. 9 A schematic diagram showing the structure of a computer device in an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0029] The following is an explanation of the embodiments of the present disclosure by specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the information disclosed by the present disclosure. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in the present disclosure can also be modified or changed in various ways according to different viewpoints and application modules without departing from the spirit of the present disclosure. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0030] The following is a detailed description of the embodiments of the present disclosure with reference to the accompanying drawings so that those skilled in the art can easily implement the present disclosure. The present disclosure can be embodied in many different forms and is not limited to the embodiments described herein.

[0031] In the representations of the present disclosure, the reference terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" and the like mean that the specific features, structures, materials or characteristics represented in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. Moreover, the specific features, structures, materials or characteristics represented may be combined in any one or a group of embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples represented in the present disclosure and the features of different embodiments or examples, unless they are mutually contradictory.

[0032] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the representation of the present disclosure, "a group" means two or more, unless otherwise clearly and specifically defined.

[0033] In order to clearly describe the present disclosure, components not related to the description are omitted, and the same reference numerals are given to the same or similar components throughout the specification.

[0034] Throughout the specification, when a device is said to be "connected" to another device, this includes not only the case of "direct connection" but also the case of "indirect connection" by placing other elements therebetween. In addition, when a device is said to "include" a certain component, unless otherwise stated, it does not exclude other components, but means that other components may be included.

[0035] Although the terms first, second, etc. are used to represent various elements in this article in some examples, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, the first interface and the second interface, etc. are represented. Moreover, as used in this article, the singular forms "one", "one" and "the" are intended to also include plural forms, unless there is an opposite indication in the context. It should be further understood that the terms "comprising" and "including" indicate that there are the described features, steps, operations, elements, modules, projects, kinds, and / or groups, but do not exclude the existence, occurrence or addition of one or a group of other features, steps, operations, elements, modules, projects, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Only when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way, will there be an exception to this definition.

[0036] The technical terms used herein are only used to refer to specific embodiments and are not intended to limit the present disclosure. The singular form used herein also includes the plural form unless the sentence clearly indicates the contrary meaning. The meaning of "including" used in the specification is to specify specific characteristics, regions, integers, steps, operations, elements and / or components, and does not exclude the existence or addition of other characteristics, regions, integers, steps, operations, elements and / or components.

[0037] Although not defined differently, all terms, including technical and scientific terms used herein, have the same meaning as those generally understood by those skilled in the art to which the present disclosure belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with relevant technical literature and the message of the present disclosure, and shall not be overly interpreted as ideal or very formal meanings unless defined.

[0038] Plasma etching is a dry etching technology widely used in semiconductor manufacturing and other micro-nano processing fields. It uses active particles such as high-energy ions and free radicals in the plasma to physically bombard and chemically react with the surface of the material, thereby achieving precise etching of the material. During the etching process, endpoint detection is required to monitor the etching process and stop etching at the etching endpoint to obtain a precise etching amount.

[0039] Common endpoint detection methods in the industry include optical emission spectroscopy and optical interferometry.

[0040] like Figure 1 As shown, a schematic diagram of a device for measuring etching endpoint using optical emission spectroscopy in an embodiment of the present disclosure is shown.

[0041] exist Figure 1 In the reaction chamber 101 of the reaction processing equipment, a sample (such as a semiconductor wafer or other type of material) is formed. Figure 1 The plasma 103 (omitted in the figure). The wall of the reaction chamber 101 is provided with a light-transmitting portion 111, and the light-transmitting portion 111 can be constructed of a light-transmitting material, such as a sapphire sheet. The spectrum detection device 102 receives the light emission of the plasma 103 through the light-transmitting portion 111 and detects the spectrum in real time. Since the spectrum will change significantly when etching to different material layers, especially when the etching end point is reached, the composition of the gas phase and the etched film will undergo chemical changes due to the conversion of the etched material, and this change is manifested by the change in the intensity of the spectral signal. For reference Figure 2 As shown in FIG. 1 , the light intensity variation process during etching is shown, which is presented by the light intensity increase at the beginning of the thin film layer during etching and the light intensity decrease at the end of the thin film layer. Therefore, by continuously monitoring the emission of the plasma 103, it is possible to detect this variation using optical emission spectroscopy and use it to determine the time of the etching end point.

[0042] For the optical interferometry method, please refer to Figure 3 , which is a schematic diagram of a device for measuring the etching endpoint using the optical interference method in one embodiment of the present disclosure.

[0043] exist Figure 3 In the display device, the display device includes a light source 104, which emits a detection light, and the output end of the detection light corresponds to the light-transmitting portion 111 on the wall of the reaction chamber 101. A carrier (not shown) carrying the sample 200 is provided in the reaction chamber 101, and the detection light passes through the light-transmitting portion 111 to illuminate the surface of the thin film layer 201 of the sample 200, and the reflected echo light is received and transmitted to the spectrum detection device 102 for spectral analysis to detect the film thickness. As an example, the transmission of the detection light and the echo light can be performed by setting an optical transmission component 105, and the optical transmission component 105 can include a first optical fiber 151 and a second optical fiber 152. The light source 104 outputs the detection light to the light-transmitting portion 111 through the first optical fiber 151, and the echo light is transmitted to the spectrum detection device 102 by the second optical fiber 152 corresponding to the light-transmitting portion 111 and optically connected to the spectrum detection device 102.

[0044] Exemplarily, the carrier may be located at the bottom of the reaction chamber 101, and the top surface of the carrier is the sample 200 loading surface. The sample 200 is disposed on the loading surface, and a thin film layer 201 is formed on the upper surface. Other layers such as a base layer may be included under the thin film layer 201.

[0045] To simplify the calculation, the incident angle of the detection light and the reflection angle of the reflected light are omitted, and the detection light may be incident perpendicular to the surface of the thin film layer 201 , so that the incident angle and the reflection angle are zero.

[0046] Can be referenced together Figure 4 As shown, when the detection light passes through the light-transmitting portion 111 and irradiates the surface of the thin film layer 201, a part of the light will be reflected by the surface of the thin film layer 201 to form a first reflected light, while the other part passes through the thin film layer 201 and is reflected on its lower surface to form a second reflected light. The phase difference between the first reflected light and the second reflected light depends on the thickness of the thin film layer 201 and the wavelength of the detection light. The first reflected light and the second reflected light will interfere with each other to form an interference signal, and the echo light contains the interference signal. Furthermore, if the phase difference between the first reflected light and the second reflected light is an odd number of times the wavelength, they will cancel each other out, causing the interference between the first reflected light and the second reflected light to be weakened, so that their interference signals appear as dark stripes. If the phase difference is an even number of times the wavelength, the interference between the first reflected light and the second reflected light will be enhanced, so that their interference signals appear as bright stripes. Thus, as Figure 5 As shown, the spectrum detection device 102 analyzes the spectrum curve of the reflected light (the horizontal axis is time, the vertical axis is light intensity), wherein the interference peaks / valleys correspond to the bright fringes with enhanced interference and the dark fringes with disappeared interference. By observing the number and spacing of the interference peaks / valleys (i.e., interference fringes), the thickness of the film can be inferred, and the etching depth relative to the film thickness can also be calculated accordingly.

[0047] Specifically, since the second reflected light has twice the film thickness in the round trip compared to the first reflected light, the optical path difference between the first reflected light and the second reflected light can be calculated:

[0048] Formula (1)

[0049] Wherein n is the refractive index of the thin film layer 201 , and d is the real-time thickness of the thin film layer 201 .

[0050] During the etching process, the change in the thin film layer 201 in each single cycle is:

[0051] Formula (2)

[0052] Where λ is the wavelength of the detection light.

[0053] By observing the period of the interference fringes and the time difference δ between adjacent peaks / troughs, the etching rate is obtained as:

[0054] Formula (3)

[0055] Accordingly, the etching depth (i.e. the etching amount in a certain period of time) can be calculated as:

[0056] Formula (4)

[0057] N represents the number of single etching cycles implemented within a certain period of time (i.e. the number of corresponding interference fringes). At this point, the actual etching depth can be calculated.

[0058] Since there is a demand for shallow etching in the industry, it corresponds to etching a shallow thickness in the thin film layer 201. On the one hand, the thin film layer 201 is not completely etched, so the optical emission spectroscopy method cannot be used. The OES method is only applicable to the obvious material changes that occur after the thin film layer 201 is completely etched, thereby forming the change of the excitation spectrum in the process of the reaction generated gas in the cavity being converted into the reaction gas. Due to the demand for shallow etching, there is no complete etching in this application, and the spectrum does not change. At the same time, for shallow etching, the range of film thickness detection by interference method is usually a few microns to hundreds of microns, which is limited by the selected observation band and the number of interference fringes. The more interference fringes, the more accurate the detection, and the fewer interference fringes, the farther the detected value deviates from the actual value. At present, the industry generally uses the method of counting the number of cycles (i.e., N in Formula 4) to calculate the film thickness. The number of cycles can be counted according to the peak / valley number of the interference signal. The methods include maximum calibration, zero calibration, derivative calibration, etc. However, for shallow etching, sometimes the number of cycles counted is even less than one cycle, which is not enough to calculate the accurate etching amount, resulting in the inability to use the interference method.

[0059] In view of this, an etching depth detection device and method are provided in an embodiment of the present disclosure, which effectively solves the problems in the related art by performing frequency domain analysis on the interference signal and selecting a suitable frequency to calculate the accurate number of cycles.

[0060] like Figure 6 As shown, a schematic diagram of the structure of an etching depth detection device in an embodiment of the present disclosure is shown.

[0061] The etching depth detection device includes a detection component 601 and a processing unit 602 .

[0062] The detection component 601 is configured to output a detection signal to the sample carrier surface in the reaction chamber where the sample 200 is placed, and receive an echo signal of the detection signal reflected by the thin film layer of the sample. As an example, the detection component 601 may include a light source and an optical transmission component. The detection light output by the light source reflects the first reflected light and the second reflected light on the upper and lower surfaces of the thin film layer on the surface of the sample 200, respectively, to form interference, and the echo signal includes the interference signal. The optical transmission component may be implemented as an optical fiber, etc. Specifically, to simplify calculations, the detection signal is configured to be incident on the thin film layer at an angle perpendicular to the sample carrier surface (i.e., the surface of the thin film layer).

[0063] The processing unit 602 is coupled to the detection component 601, and is used to obtain the accurate current etching depth according to the echo signal processing. In some embodiments, the processing unit 602 can be implemented as a controller in a spectrum detection device, and the spectrum detection device optical path is connected to the optical transmission component to obtain the echo signal. In some other embodiments, the processing unit 602 can be implemented as a processing terminal external to the spectrum detection device, such as a server, a desktop, a laptop, a smart phone or a tablet computer, etc., for running a computer program to obtain the current etching depth.

[0064] Specifically explaining the principle, according to formulas (1) to (4), it can be found that the change amount of the thin film layer in a single cycle responds differently to different signal wavelengths λ. The change amount of the thin film layer in a single cycle corresponding to a larger wavelength is larger, and the change amount of the thin film layer in a cycle corresponding to a smaller wavelength is larger. Therefore, when etching a thin film layer of the same film thickness, different wavelengths of light are selected as the observation light, and the observed interference periodic signals are different. In order to overcome the difficulty in determining the number of periods of the actual interference signal in formula (4), that is, N, due to the small number of signal periodic data or even less than one, it is impossible to calculate the accurate thickness d er Therefore, we will consider using a light source with rich wavelengths to provide various wavelengths of detection light, and analyze the full spectrum data obtained by the detection light. By observing multiple signal wavelengths λ1, λ2, λ3, λ4…λ m D er To get the exact d er . To be more specific, the relationship between the signal wavelength and frequency is λ=u / f, where u is the wave speed. When the signal is light, the wave speed is the speed of light. For wavelengths λ1, λ2, λ3, λ4…λ m , corresponding to different signal frequencies f1, f2, f3, f4…f m Therefore, a light source with rich wavelengths can be implemented as a light source with a large frequency bandwidth, thereby including detection signals (such as detection light) of multiple frequencies, and an echo signal containing interference signals of multiple frequencies can be received.

[0065] Therefore, by performing frequency domain analysis on the echo signal, such as Fourier transform (such as discrete Fourier transform, fast Fourier transform) and other methods, the time domain signal of the echo signal can be converted into a frequency domain signal, thereby decomposing components of different frequencies. Through frequency domain analysis, the echo signal can be decomposed into sinusoidal components of different frequencies (i.e., interference signal components of different frequencies). Even if the signal is not a complete cycle, the Fourier transform can provide frequency information present in the signal. Even when the signal length is less than one cycle, the frequency obtained by Fourier transform can still provide a useful estimate.

[0066] Discrete Fourier Transform (DFT):

[0067] The discrete Fourier transform converts a discrete time signal into the frequency domain, and its formula is:

[0068] X(k) = Σ[n=0, P-1] x(n) · exp(-j·2πkn / P)

[0069] Where k is the kth frequency, P is the number of sampling points in the time domain, x(n) is the sampling value of the time domain signal at time n, X(k) is the complex number representation of the kth frequency component in the frequency domain, and j is the imaginary symbol in the complex number.

[0070] Fast Fourier Transform (FFT) is an algorithm for efficiently calculating Discrete Fourier Transform (DFT). It can convert time domain signals into frequency domain signals and is used in signal processing and spectrum analysis in many fields.

[0071] Therefore, according to the obtained f1, f2, f3, f4…f m The frequency components of the unit cycle are shown in Table 1. Since the reciprocal of the frequency f is the unit cycle length T, we can get T1, T2, T3, T4…T m By setting the preset etching time T total Divide by T1, T2, T3, T4…T respectively m , we can get m cycles N1~N m For shallow moments, the number of cycles may be less than one cycle, so the number of cycles N1~N m may be less than 1. Then, N1~N m Substitute into formula (4) as N, λ1, λ2, λ3, λ4…λ m Substituting into equation (2) we obtain Δd1, Δd2, … Δd m , and then correspond to N1~N m Substitute into formula (4) to calculate the m basic etching depths d er1 ~d erm, and then calculate the accurate current etching depth d based on the m basic etching depths er The reason for calculating multiple basic etching depths is that the Fourier transform may have certain errors in estimating the frequency, especially when the signal is noisy or the signal length is very short. Therefore, on the one hand, the mathematical expectation value (weighted sum) can be calculated for m basic etching depths. For example, the average is used to obtain the target etching depth d er =(d er1 +d er2 +d er3 +d er4 +...d erm ) / m.

[0072] On the other hand, optionally, in order to achieve a better noise reduction effect, some noise reduction measures may be used according to the error conditions of the m basic etching depths and the error conditions of the actual signal to improve the accuracy of the current etching depth.

[0073] The above introduces the basic principle of calculating the current etching depth in the embodiment of the present disclosure. In a specific example, the processing unit 602 can execute the etching depth detection method designed based on the above principle to obtain the current etching depth. Figure 7 As shown, a schematic diagram of the process of the etching depth detection method is shown.

[0074] The method comprises:

[0075] Step S701: Decompose the echo signal to obtain a group of target frequency components, and divide the preset etching duration by the period length corresponding to the target frequency of each target frequency component to obtain a corresponding number of periods to form a group of period numbers.

[0076] In some embodiments, the echo signal may be an optical signal, which is converted into an electrical signal after photoelectric conversion, and the analysis is performed on the basis of the converted electrical signal. As an example, the time domain signal is converted into a frequency domain signal by Fourier transform to obtain a set of frequency components. In a further optional embodiment, the interference frequency component can be excluded from the set of frequency components to obtain the target frequency component. The interference frequency component is consistent with the frequency of the radiation signal generated during the reaction process in the reaction chamber. For example, a plasma for etching the sample is formed in the reaction chamber. Then, the radiation signal includes at least one of the following: an optical signal excited by the gas in the reaction chamber; a radiation signal generated by the plasma in the reaction chamber in at least one state of ionization, excitation, deexcitation, radiation transition, recombination, and charge exchange. That is, from the set of frequency components, the remaining frequency components other than the various frequencies of the radiation signal are screened out to serve as or select the target frequency component.

[0077] ‌Light source bandwidth refers to the frequency range of the light emitted by the light source. Based on the above principle, when selecting a light source, the light source can be selected to have a frequency bandwidth (i.e., spectral bandwidth) that can provide a rich set of other frequencies in addition to the frequencies of the above interference frequency components, so that the set of basic moment depths (d er1 ~d erm ) is large enough so that the target etching depth calculated in the end is more accurate. In some embodiments, in the frequency component set excluding the interference frequency components, some frequency components with weaker amplitudes can be excluded in combination with the amplitude, and some frequency components with peak amplitudes can be selected as target frequency components, or the target frequency components can be selected from the remaining frequency components through a window function to reduce the problem of "false spectrum" caused by spectrum leakage (i.e., smaller amplitudes that do not actually exist at other frequency points on both sides of the spectrum due to the mutual influence between the spectrum lines).

[0078] Step S702: Determine the amount of change in the thin film layer within a single cycle based on the target signal wavelength corresponding to each target frequency and the refractive index of the thin film layer, and multiply the amount of change in the thin film layer corresponding to each target frequency component in a group of target frequency components by the number of cycles corresponding to the target frequency component in the group of cycles to obtain each basic etching depth, thereby forming a group of basic etching depths.

[0079] In some embodiments, referring to equation (2), the wavelength of the detection light is known, the material of the thin film layer is known, and the refractive index n is known, and the change amount of the thin film layer can be calculated.

[0080] Step S703: obtaining a current etching depth based on a mathematical expectation of a set of basic etching depths.

[0081] Ideally, sample d er1 ~d erm If the samples are equal or close to each other, we can directly calculate the mathematical expectation, such as the weighted sum of the mean. However, if the difference between the samples is large, it means that the sample d er1 ~d erm If there is too much noise, it is not suitable to directly calculate the mathematical expectation value.

[0082] For this reason, Figure 8 As shown, step S703 may also include:

[0083] Step S801: determining whether the difference between the group of basic etching depths meets a preset quality condition.

[0084] In some embodiments, the difference is expressed as the variance (σ 2), standard deviation (σ) and goodness of fit (GOF). Accordingly, the preset quality condition can be set to whether the difference between the basic etching depths satisfies the variance (σ 2 ), standard deviation (σ), and goodness of fit (GOF) settings.

[0085] Step S802: In response to satisfying a preset quality condition, a current etching depth is obtained based on a mathematical expectation of the set of basic etching depths.

[0086] If it is satisfied, it means that the difference is small and the sample quality is good. The current etching depth can be directly obtained through mathematical expectation (such as weighted sum of mean value).

[0087] Step S803: In response to not meeting the preset quality condition, performing noise reduction processing on the group of basic etching depths, and obtaining a current etching depth based on a mathematical expectation of the group of basic etching depths after the noise reduction processing.

[0088] In some embodiments, the noise reduction process includes at least one of the following: preprocessing; outlier detection and elimination. In some embodiments, the preprocessing may include at least one of smoothing, interpolation, and denoising. As an example, the smoothing process mainly involves several methods, including mean smoothing, Gaussian smoothing, median smoothing, moving average method, etc. As an example, a continuous function is interpolated on the basis of discrete data so that this continuous curve passes through all given discrete data points. Interpolation is an important method for approximating discrete functions. It can be used to estimate the approximate value of the function at other points by the value of the function at a finite number of points. As an example, as described above, the signal-to-noise ratio of the collected spectrum is increased by avoiding interference frequencies such as plasma luminescence to reduce noise. As an example, outliers in the frequency components and / or basic etching depth sets can be identified and processed by outlier detection and correction methods and corrected or eliminated according to the situation. Further exemplary, outlier detection methods may include statistical methods (such as the 3σ principle), visualization methods (such as box plots), or special outlier detection algorithms to identify outliers.

[0089] Finally, after the noise reduction process, multiple sets of target frequency components (corresponding signal wavelength spectra) can be combined to calculate the duration T at the current moment. total The current etching depth d er .

[0090] In some embodiments, an etching endpoint detection device may also be formed based on the etching depth detection device. As an example, the method may further include S704: in response to the current etching depth reaching the etching endpoint, the reaction processing device stops etching.

[0091] In the embodiment of the present disclosure, a reaction processing device may be provided, including a reaction chamber and an etching depth detection device. The reaction processing device includes a reaction chamber, wherein a carrier is arranged in the reaction chamber, and has a sample carrying surface for carrying a sample. The etching depth detection device may be used to detect the current etching depth of the thin film on the surface of the sample in the reaction chamber. The reaction processing device may be exemplified as a plasma processing device, and its arrangement structure may be, for example, Figure 3 The structure of the etching depth detection device can be realized by referring to Figure 6 Example.

[0092] As an optional example in the above embodiments, a detection signal is outputted by a light source with a large bandwidth of a detection component, and the echo signal formed by the interference of multiple reflection signals reflected by the detection signal on the film is subjected to frequency domain analysis, and then a frequency component set is obtained by frequency domain analysis to obtain a target frequency component excluding the interference frequency, thereby accurately calculating the number of each cycle according to each target frequency component and a preset etching time, and combining the target signal wavelength based on the corresponding target frequency component, the refractive index of the film, etc. to obtain a basic etching depth set, and the basic etching depth set that meets the preset quality conditions is used to obtain the expected accurate current etching depth. Therefore, in the case of shallow etching where the common "counting cycles" method is not applicable, the interference method can also be used to obtain the accurate etching depth of the thin film layer, effectively solving the problem of endpoint detection of shallow etching in related technologies.

[0093] It should be particularly noted that the process or method represented by the flowchart of the above embodiment of the present disclosure can be understood as representing a module, fragment or part of a code including one or more sets of executable instructions configured to implement the steps of a specific logical function or process. And the scope of the preferred embodiment of the present disclosure includes other implementations, in which the functions may not be performed in the order shown or discussed, including performing the functions in a substantially simultaneous manner or in a reverse order according to the functions involved.

[0094] For example, Figure 7 , Figure 8 The order of the steps in the method embodiments may be changed in specific scenarios and is not limited to the above.

[0095] like Fig. 9 , which shows a schematic diagram of the structure of a computer device in one embodiment of the present disclosure.

[0096] The computer device 900 may be exemplified as a processor in a spectral detection device or a processing terminal communicatively coupled to the spectral detection device, such as a server, a desktop computer, a laptop computer, a tablet computer, a smart phone or other terminals.

[0097] The computer device 900 includes a bus 901, a processor 902, and a memory 903. The processor 902 and the memory 903 can communicate with each other through the bus 901. The memory 903 can store a computer program or instruction. The processor 902 implements the process steps performed by the processing unit in the previous embodiment by running the computer program or instruction in the memory 903.

[0098] The bus 901 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, although only one thick line is used in the figure, it does not mean that there is only one bus or one type of bus.

[0099] In some embodiments, the processor 902 may be implemented as a central processing unit (CPU), a microprocessing unit (MCU), a system on chip (System On Chip), or a field programmable logic array (FPGA). The memory 903 may include a volatile memory (Volatile Memory) for temporary storage of data when running a program, such as a random access memory (Random Access Memory, RAM).

[0100] The memory 903 may also include a non-volatile memory (non-volatile memory) for data storage, such as a read-only memory (ROM), a flash memory, a hard disk drive (HDD), or a solid-state disk (SSD).

[0101] In some embodiments, the computer device 900 may further include a communicator 904. The communicator 904 is used to communicate with the outside. In a specific example, the communicator 904 may include one or a group of wired and / or wireless communication circuit modules. For example, the communicator 904 may include one or more of a wired network card, a USB module, a serial interface module, etc. The wireless communication protocols followed by the wireless communication module include: for example, near field communication (NFC) technology, infrared (IR) technology, Global System for Mobile communications (GSM), General Packet Radio Service (GPRS), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), Time-Division Code Division Multiple Access (TD-SCDMA), Long Term Evolution (LTE), Bluetooth (BT), Global Navigation Satellite System (GNSS), etc. One or more.

[0102] In an embodiment of the present disclosure, a computer-readable storage medium may be provided, storing a computer program or instruction, wherein the computer program or instruction is executed to implement the steps of the method flow in any of the previous embodiments, such as Figure 7 , Figure 8 .

[0103] That is, the method steps in the above embodiments are implemented as software or computer code that can be stored in a recording medium (such as a CD ROM, RAM, floppy disk, hard disk or magneto-optical disk), or are implemented as computer code originally stored in a remote recording medium or a non-temporary machine-readable medium downloaded via a network and to be stored in a local recording medium, so that the method represented herein can be stored in such software processing on a recording medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware (such as an ASIC or FPGA).

[0104] The present disclosure may also provide a computer program product, one or more computer programs or instructions, which when executed fully or partially execute the process or function of the present disclosure. Figure 7 , Figure 8 The computer program product comprises one or more computer programs or instructions.

[0105] The computer program or instructions may be stored in a readable storage medium or transmitted from one readable storage medium to another readable storage medium, for example, the computer program or instructions may be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired or wireless means. The readable storage medium may be any available medium that can be accessed or a data storage device such as a server, data center, etc. that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; it may also be an optical medium, such as a digital video disk; it may also be a semiconductor medium, such as a solid state drive. The computer readable storage medium may be a volatile or non-volatile storage medium, or may include both volatile and non-volatile types of storage media.

[0106] In summary, an etching depth detection device, method and reaction processing equipment are provided in the embodiments of the present disclosure, and the device includes: a detection component, which is configured to output a detection signal to the sample carrier surface in the reaction chamber, and receive an echo signal reflected by the detection signal in the thin film layer of the sample; the echo signal includes an interference signal of the reflection signal on different surfaces of the thin film layer; a processing unit, coupled to the detection component, is used to decompose the echo signal to obtain a group of target frequency components, and divide the preset etching time by the period length corresponding to the target frequency of each target frequency component to obtain the corresponding number of periods to form a group of period numbers, and each target frequency corresponds to a target signal wavelength; determine the amount of change of the thin film layer within a single period according to the target signal wavelength corresponding to each target frequency and the refractive index of the thin film layer, and multiply the amount of change of the thin film layer corresponding to each target frequency component in a group of target frequency components by the corresponding number of periods of the target frequency component in the group of period numbers to obtain each basic etching depth to form a group of basic etching depths; and obtain the current etching depth based on the mathematical expectation of a group of the basic etching depths. Therefore, in the case of shallow etching and incomplete etching of the etched film layer, an accurate number of cycles can be obtained to calculate the accurate etching depth, so as to make an accurate endpoint detection for the etching process.

[0107] The above embodiments are merely illustrative of the principles and effects of the present disclosure, and are not intended to limit the present disclosure. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the present disclosure shall still be covered by the protection scope of the present disclosure.

Claims

1. An etching depth detection device, characterized in that: Applied to a reaction processing device, the reaction processing device comprises a reaction chamber; the etching depth detection device comprises: A detection component is configured to output a detection signal to the sample carrier surface in the reaction chamber, and receive an echo signal of the detection signal reflected by the thin film layer of the sample; the echo signal includes an interference signal of the reflection signals on different surfaces of the thin film layer; A processing unit, coupled to the detection component, is used to decompose the echo signal to obtain a group of target frequency components, and divide the preset etching time by the period length corresponding to the target frequency of each target frequency component to obtain the corresponding number of periods to form a group of period numbers; each target frequency corresponds to a target signal wavelength; the amount of change of the thin film layer within a single period is determined according to the target signal wavelength corresponding to each target frequency and the refractive index of the thin film layer, and the amount of change of the thin film layer corresponding to each target frequency component in a group of target frequency components is multiplied by the number of periods corresponding to the target frequency component in the group of period numbers to obtain each basic etching depth to form a group of basic etching depths; and the current etching depth is obtained based on the mathematical expectation of a group of the basic etching depths, and the mathematical expectation is a weighted sum; the decomposition of the echo signal to obtain a group of target frequency components includes: in the set of frequency components obtained by decomposing the echo signal, excluding the interference frequency component to obtain the target frequency component; wherein the interference frequency component is consistent with the frequency of the radiation signal generated during the reaction process in the reaction chamber.

2. The etching depth detection device according to claim 1, characterized in that: The detection signal is configured to be incident on the thin film layer at an angle perpendicular to the sample loading surface.

3. The etching depth detection device according to claim 1, characterized in that: A plasma for etching the sample is formed in the reaction chamber; the radiation signal includes at least one of the following: a light signal excited by the gas in the reaction chamber; a radiation signal generated by the plasma in the reaction chamber in at least one state of ionization, excitation, deexcitation, radiation transition, recombination, and charge exchange.

4. The etching depth detection device according to claim 1, characterized in that: The step of obtaining a current etching depth based on a mathematical expectation of a set of basic etching depths further includes: Determining whether the difference between the basic etching depths of the group meets the preset quality condition; In response to satisfying a preset quality condition, obtaining a current etching depth based on a mathematical expectation of the set of basic etching depths; In response to not meeting the preset quality condition, the group of basic etching depths is subjected to noise reduction processing, and a current etching depth is obtained based on a mathematical expectation of the group of basic etching depths after the noise reduction processing.

5. The etching depth detection device according to claim 4, characterized in that: The difference is obtained by at least one of variance, standard deviation and goodness of fit; and / or, the noise reduction processing includes at least one of the following: preprocessing, including at least one of smoothing, interpolation, and denoising; outlier detection and elimination.

6. The etching depth detection device according to claim 1, characterized in that: The processing unit is further configured to stop the etching operation of the reaction processing device in response to the current etching depth reaching an etching endpoint.

7. A method for detecting etching depth, characterized in that: Applied to a reaction processing device, the reaction processing device includes a reaction chamber; the etching depth detection method includes: Acquire a detection signal output to the sample carrier surface in the reaction chamber, and receive an echo signal reflected by the detection signal; the echo signal includes an interference signal between reflection signals of the detection signal on the upper and lower surfaces of the thin film layer of the sample; Decomposing the echo signal to obtain a group of target frequency components, and dividing the period length corresponding to the target frequency of each target frequency component by a preset etching time to obtain a corresponding number of periods to form a group of period numbers, wherein each target frequency corresponds to a target signal wavelength; Decomposing the echo signal to obtain a group of target frequency components includes: in a set of frequency components decomposed based on the echo signal, excluding interference frequency components to obtain target frequency components; wherein the interference frequency components are consistent with the frequency of the radiation signal generated during the reaction process in the reaction chamber; Determine the amount of change of the thin film layer within a single cycle according to the target signal wavelength corresponding to each target frequency and the refractive index of the thin film layer, and multiply the amount of change of the thin film layer corresponding to each target frequency component in a group of target frequency components by the number of cycles corresponding to the target frequency component in the group of cycles to obtain each basic etching depth to form a group of basic etching depths; and The current etching depth is obtained based on a mathematical expectation of a group of basic etching depths, where the mathematical expectation is a weighted sum.

8. The etching depth detection method according to claim 7, characterized in that: The step of obtaining a current etching depth based on a mathematical expectation of a set of basic etching depths further includes: Determining whether the difference between the basic etching depths of the group meets the preset quality condition; In response to satisfying a preset quality condition, obtaining a current etching depth based on a mathematical expectation of the set of basic etching depths; In response to not meeting the preset quality condition, the group of basic etching depths is subjected to noise reduction processing, and a current etching depth is obtained based on a mathematical expectation of the group of basic etching depths after the noise reduction processing.

9. A reaction processing device, characterized in that: include: The reaction chamber comprises: a carrier having a sample carrying surface for carrying a sample; The etching depth detection device according to any one of claims 1 to 6.

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