Method for calibrating a measuring device, standard sample for calibration and method for preparing the same

Abstract

The application provides a calibration method of a measuring device, a standard sample for calibration and a preparation method of the standard sample. The calibration method comprises the following steps: adopting a standard device to perform first measurement on the content of a target element contained in each layer of a multilayer film to be detected, wherein the content of the target element contained in each layer of the multilayer film to be detected changes in the same trend in the thickness direction of the multilayer film to be detected; adopting a measuring device to perform second measurement on the content of the target element contained in each layer of the multilayer film to be detected; and calibrating the measuring device based on the results of the first measurement and the second measurement.

Description

Technical Field

[0001] This application relates to the field of testing. Specifically, this application relates to a calibration method for a measuring device, a standard sample for calibration, and a method for preparing the same. Background Technology

[0002] Planar NAND devices have reached the limits of practical expansion. In order to further increase storage capacity and reduce the storage cost per bit, 3D NAND memory devices with vertical channel structures have been developed.

[0003] The channel structure of 3D NAND typically includes SiO2. x -SiO x N x -SiO x N y The ONO (On-Organic) structure consists of a barrier layer, a charge trapping layer, and a tunneling layer. The tunneling layer acts as a barrier for electrons to tunnel from the channel to the charge trapping layer, while the charge trapping layer traps and stores the tunneled electrons. Therefore, the elemental composition and distribution of the charge trapping and tunneling layers significantly influence the storage, programming, and readout performance of 3DNANDs. In practical detection, the nitrogen (N) content distribution in the ONO structure is a crucial compositional indicator.

[0004] It should be understood that the background section is intended to provide some useful background for understanding the technology; however, this content is not necessarily what was known or understood by a person skilled in the art prior to the filing date of this application.

[0005] Summary of the Invention This application provides a calibration method for a measuring device, comprising: performing a first measurement on the content of a target element contained in each layer of a multilayer film to be tested using a standard device, wherein the content of the target element contained in each layer of the multilayer film to be tested varies with the same trend in the thickness direction of the multilayer film to be tested; performing a second measurement on the content of the target element contained in each layer of the multilayer film to be tested using the measuring device; and calibrating the measuring device based on the results of the first measurement and the second measurement.

[0006] In one embodiment of this application, the first measurement of the content of target elements contained in each layer of a multilayer test film using a standard device includes: a1) forming a test film and measuring the content of target elements contained in the test film using the standard device; and a2) repeating step a1) until a multilayer test film is formed and the first measurement is completed.

[0007] In one embodiment of this application, the second measurement of the content of target elements contained in each layer of the multilayer film to be tested using the measuring device includes: forming a standard sample including the multilayer film to be tested; cutting a sample of a preset size from the standard sample and including the multilayer film to be tested as a sample to be tested; and performing the second measurement on each layer of the multilayer film to be tested in the sample to be tested.

[0008] In one embodiment of this application, the second measurement of the content of target elements contained in each layer of the multilayer test film using the measuring device includes: b1) measuring the content of target elements contained in a layer of the multilayer test film included in the test sample that is closest to the measuring device using the measuring device; b2) removing a layer of the multilayer test film that is closest to the measuring device to expose the next layer of the multilayer test film; b3) measuring the content of target elements contained in the next layer of the multilayer test film; and b4) repeating steps b2) and b3) until the second measurement is completed.

[0009] In one embodiment of this application, the sample to be tested includes multiple collection areas divided along the thickness direction of the film layer to be tested. The second measurement of the content of the target element contained in each layer of the multilayer film layer to be tested using the measuring device includes: sequentially scanning the multiple collection areas with an electron beam to obtain multiple spectra containing the content information of the target element; and superimposing the spectra of the multiple collection areas to complete the second measurement.

[0010] In one embodiment of this application, calibrating the measuring device based on the results of the first measurement and the second measurement includes: linearly fitting a plurality of standard values ​​obtained from the first measurement with a plurality of measurement values ​​obtained from the second measurement; and calibrating the measuring device in response to the regression coefficient after the linear fitting being less than a preset value.

[0011] In one embodiment of this application, the difference in the content of the target element contained in adjacent membrane layers to be tested is greater than or equal to 0.2% and less than 2%.

[0012] In one embodiment of this application, the standard apparatus is used to measure the target elements contained in each layer of the multilayer film to be tested at the same time.

[0013] In one embodiment of this application, the time for measuring the target elements contained in each layer of the multilayer film to be tested using the standard device is ≤1 hour.

[0014] In one embodiment of this application, each layer of the multilayer film to be tested comprises silicon oxynitride, and the target element comprises at least one of nitrogen, silicon, or oxygen.

[0015] Another aspect of this application provides a method for preparing a standard sample for calibration, comprising: forming multiple layers of test films containing a target element on a substrate, wherein the content of the target element contained in each layer of the multiple test films varies with the same trend in the thickness direction of the multiple test films; and forming a protective layer on the multiple test films to form the standard sample.

[0016] In one embodiment of this application, the preparation method further includes: forming an insulating layer on the substrate before forming multiple layers of the film to be tested.

[0017] In one embodiment of this application, the difference in the content of the target element contained in adjacent membrane layers to be tested is greater than or equal to 0.2% and less than 2%.

[0018] In one embodiment of this application, each of the films to be tested comprises silicon oxynitride, and the target element comprises at least one of nitrogen, silicon, or oxygen.

[0019] Another aspect of this application provides a standard sample for calibration, comprising: a substrate; a multilayer film to be tested located on the substrate, wherein the content of the target element contained in each layer of the multilayer film to be tested varies with the same trend in the thickness direction of the multilayer film to be tested; and a protective layer located on the multilayer film to be tested.

[0020] In one embodiment of this application, the standard sample further includes an insulating layer located between the substrate and the multilayer film to be tested.

[0021] In one embodiment of this application, the content of the target element contained in each layer of the multilayer test film varies in an increasing trend in the direction of increasing thickness of the multilayer test film.

[0022] In one embodiment of this application, the content of the target element contained in each layer of the multilayer test film varies in a decreasing trend in the direction of increasing thickness of the multilayer test film.

[0023] In one embodiment of this application, the difference in the content of the target element contained in adjacent membrane layers to be tested is greater than or equal to 0.2% and less than 2%.

[0024] In one embodiment of this application, the film to be tested comprises silicon oxynitride, and the target element comprises at least one of nitrogen, silicon, or oxygen.

[0025] In one embodiment of this application, the insulating layer comprises silicon oxide, and the protective layer comprises polycrystalline silicon.

[0026] In one embodiment of this application, the thickness of each layer in the multilayer test film ranges from 1 nm to 30 nm. Attached Figure Description

[0027] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. In the drawings, Figure 1 This is a schematic flowchart of a calibration method according to some embodiments of this application.

[0028] Figure 2 and Figure 3 This is a schematic diagram of a calibration method according to some embodiments of this application, showing a first measurement being performed.

[0029] Figure 4 This is a schematic structural diagram of a calibration method according to some embodiments of this application after the formation of a standard sample.

[0030] Figure 5 and Figure 6 This is a schematic diagram of a second measurement performed in a calibration method according to some embodiments of this application.

[0031] Figure 7 This is a schematic diagram of a second measurement performed according to a calibration method based on some other embodiments of this application.

[0032] Figure 8 XPS spectra obtained by a measuring device after calibration according to some embodiments of this application.

[0033] Figure 9 The EELS spectrum is obtained by a measuring device after calibration according to the calibration method of some other embodiments of this application.

[0034] Figure 10 This is a linear fit graph of measured values ​​obtained by Lab XPS and TOF SIMS devices after multiple calibrations and standard values ​​obtained by Inline XPS devices, according to calibration methods of other embodiments of this application.

[0035] Figure 11 This is a flowchart of a method for preparing a standard sample for calibration according to some embodiments of this application.

[0036] Figure 12 and Figure 13 This is a schematic flowchart illustrating a method for preparing a standard sample for calibration according to some embodiments of this application. Detailed Implementation

[0037] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements.

[0038] Note that references to "exemplarily," "in some examples," "some implementations," etc., in the specification indicate that the described implementations may include specific features, structures, or characteristics, but each implementation may not necessarily include that specific feature, structure, or characteristic. Furthermore, these phrases do not necessarily refer to the same implementation. Additionally, when a specific feature, structure, or characteristic is described in connection with an implementation, whether explicitly stated or not, implementing that feature, structure, or characteristic in conjunction with other implementations will be within the knowledge of those skilled in the art.

[0039] It should be readily understood that the meaning of “on” in this disclosure should be interpreted in the broadest sense, such that “on” means not only “directly on something”, but also includes “on something” with intermediate features or layers in between.

[0040] As used herein, the term "layer" refers to a portion of material comprising a region of thickness. Furthermore, a layer can be a region of a continuous structure, whether homogeneous or non-homogeneous. For example, a layer can be located between the top and bottom surfaces of a continuous structure or between any pair of horizontal planes at the top and bottom surfaces of a continuous structure. A layer can extend horizontally, vertically, and / or along a tapered surface. A substrate can be a layer, and may include one or more layers, and / or may have one or more layers on, above, and / or below it. A layer can include multiple layers.

[0041] Generally, terms can be understood at least in part from their use in context. For example, depending at least in part on the context, the term “one layer or multiple layers” as used herein can be used to describe any feature, structure, or property in a singular sense, or it can be used to describe a combination of features, structures, or properties in a plural sense.

[0042] In the accompanying drawings, the thickness, dimensions, and shapes of the parts have been slightly adjusted for ease of illustration. The drawings are for illustrative purposes only and are not drawn to scale. For example, the terms “approximately,” “about,” and similar terms used herein are used as expressions of approximation, not as expressions of degree, and are intended to illustrate inherent deviations in measured or calculated values ​​that will be recognized by one of ordinary skill in the art.

[0043] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to indicate "one or more embodiments of this application."

[0044] Unless otherwise specified, all terms used herein (including engineering and technical terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that, unless expressly stated herein, terms defined in common dictionaries shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not as having an idealized or overly formalized meaning.

[0045] It should be noted that, where there is no conflict, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] As mentioned earlier, the nitrogen content distribution in the charge trapping layer and tunneling layer of the 3D NAND channel structure has a significant impact on the electrical performance of 3D NAND. In measurement devices, transmission electron microscopy (TEM) or a combination of TEM and electron energy loss spectroscopy (EELS) is typically used to analyze the composition of the charge trapping layer and tunneling layer. However, when the mass fraction difference of nitrogen between the film layers is less than 2%, the above methods often fail to yield accurate results.

[0047] Some embodiments of this application provide a calibration method for calibrating the aforementioned measuring device. Figure 1 A schematic flowchart of a calibration method 300 according to some embodiments of this application is shown. The following is in conjunction with... Figure 1 The calibration method 300 is described in detail. (Reference) Figure 1 The calibration method 300 includes step S310, wherein a standard device can be used to perform a first measurement on the content of the target element contained in each layer of the multilayer film to be tested, wherein the content of the target element contained in each layer varies with the same trend in the thickness direction of the multilayer film to be tested.

[0048] In some examples of using a standard apparatus to perform a first measurement of the content of the target element contained in each layer of a multilayer test film, a test film layer can be formed, and the content of the target element contained in this test film layer can be measured using a standard apparatus. For example... Figure 2 As shown, in step S310, a film layer 103-1 to be tested can be formed on the substrate 101 by a thin film deposition process such as chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any combination thereof. Alternatively, an insulating layer 102 can also be formed on the substrate 101 before forming the film layer 103-1 to be tested.

[0049] In some examples including the insulating layer 102, the substrate 101 may have a thicker thickness than the insulating layer 102 and the film layer 103-1 to be tested, thereby enabling it to serve as a carrier substrate. Exemplarily, the substrate 101 may be a bare wafer with a diameter (at its maximum width) ranging from 10 cm to 20 cm. The insulating layer 102 may serve as the interface layer between the substrate 101 and the film layer 103-1 to be tested. Optionally, the thickness of the insulating layer 102 may be, for example, 1 nm to 30 nm, and the thickness of the film layer 103-1 to be tested may be, for example, 1 nm to 30 nm. Alternatively, the thickness of the insulating layer 102 and the film layer 103-1 to be tested may be approximately the same. Alternatively, the thickness of the insulating layer 102 and the film layer 103-1 to be tested may be different.

[0050] In some examples, the material used for substrate 101 may include silicon (such as single-crystal silicon, polycrystalline silicon), silicon-germanium (SiGe), germanium (Ge), silicon-on-insulator (SOI), germanium-on-insulator (GOI), gallium arsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC), glass, III-V compound semiconductors, or any combination thereof. Optionally, the material used for insulating layer 102 may include, for example, silicon oxide.

[0051] In some examples, the film layer 103-1 to be tested may be deposited on the insulating layer 102 using a thin film deposition process such as CVD, PVD, ALD, or any combination thereof. Optionally, the material used for the film layer 103-1 to be tested may include, for example, silicon oxynitride.

[0052] Optionally, to make the quality of the film to be tested closer to the ONO stack structure included in the channel structure of 3D NAND, silicon oxynitride can be deposited on the insulating layer 102 as the film to be tested 103-1 using an atomic layer deposition (ALD) process. In some examples, the target element included in the film to be tested 103-1 is, for example, nitrogen. By controlling the deposition process time and gas source ratio, the thickness and nitrogen content of the formed film to be tested 103-1 can be made close to the thickness and nitrogen content of the electron trapping layer and tunneling layer in the ONO structure.

[0053] In some examples, after the film layer 103-1 to be tested is formed, the content of the target element in the film layer 103-1 to be tested can be measured by a standard device 110 to obtain a standard value of the nitrogen content of the film layer 103-1 to be tested. Optionally, a copper clip can be used to fix the substrate 101 to the sample stage for measuring the film layer 103-1 to be tested. In examples where the film layer 103-1 to be tested includes silicon oxynitride, the measurement time of the film layer 103-1 to be tested can be controlled to ≤1 hour to minimize the oxidation of silicon oxynitride in air. In other examples, the measurement time of the film layer 103-1 to be tested can be controlled to <30 minutes. Optionally, to avoid the oxidation of silicon oxynitride in air, the film layer 103-1 to be tested can also be measured under a low vacuum condition.

[0054] Optionally, the standard device 110 may be, for example, a high-precision (accuracy range, for example, greater than or equal to 0.2% and less than 2%) X-ray photoelectron spectroscopy (XPS) device (e.g., Inline XPS) used on a production line for measurement. Optionally, the surface of the film layer 103-1 to be tested can be irradiated with X-rays from the high-precision XPS device, causing the inner-shell electrons or valence electrons of the atoms or molecules in the film layer 103-1 to be excited and emitted. The electrons excited by the X-rays have a certain energy, and by measuring the number of electrons excited in the film layer 103-1 and the energy they carry, the content of each element contained therein can be determined.

[0055] In some examples, the aforementioned high-precision XPS equipment includes, for example, an X-ray generator and an electron detection device. The X-ray generator can emit X-rays onto the film layer 103-1 to be tested, and then the electron detection device can acquire the electrons excited by the X-rays in the film layer 103-1 to be tested. The nitrogen content of the film layer 103-1 to be tested can be determined based on the energy state and number of electrons acquired by the electron detection device.

[0056] For example, the electron collection mode of the electron detection device can be a snapshot mode, where the detector in the electron detection device can have 128 channels, each placed in a different energy state, to simultaneously collect electrons of different energies, so as to complete electron acquisition in a short time. In the example where the film layer 103-1 to be detected includes silicon oxynitride, the snapshot mode can be used to collect the energy spectra of silicon (Si), nitrogen (N), and oxygen (O), thereby obtaining the content of the three elements.

[0057] In some examples, the steps of forming the test film 103-1 and measuring the target element contained in the test film 103-1 can be repeated multiple times until multiple test films are formed (e.g., test films 103-1 to 103-4), and standard values ​​of the content of the target element contained in each layer of the multiple test films are obtained. In some examples, in order to ensure that the quality of each layer of the formed multiple test films is approximately the same, the same deposition process (e.g., ALD process) can be used to form the above-mentioned multiple test films.

[0058] It should be understood that during the process of forming each layer of the multilayer test film, the overall thickness of the test film continuously increases. The aforementioned thickness direction can refer to either the direction along which the overall thickness of the test film increases (away from the substrate 101) or the direction along which the overall thickness of the test film decreases (closer to the substrate 101). The following description will use the direction of the thickness of the test film increasing as an example.

[0059] In an exemplary process for forming multiple layers of a test film using a deposition process, the nitrogen content in each layer of the multilayer test film can be adjusted by controlling the proportion of each reaction source. For example, the mass fraction of nitrogen in each layer of the formed multilayer test film can be controlled to increase in the direction of increasing thickness by sequentially increasing the partial pressure of the nitrogen source in the reaction gas source. Optionally, in some cases, the mass fraction of nitrogen in each layer of the formed multilayer test film can be controlled to decrease in the direction of increasing thickness by sequentially decreasing the partial pressure of the nitrogen source in the reaction gas source. Optionally, the mass fraction of nitrogen content in each layer of the test film is, for example, 10% to 40%. In some examples, the mass fraction of nitrogen content in each layer of the test film is, for example, 25% to 30%.

[0060] For example, the deposition process can be simplified by controlling the deposition time and deposition rate so that the thicknesses of the layers in the films to be tested 301-1 to 301-4 are approximately the same. Alternatively, the thicknesses of the layers in the films to be tested 301-1 to 301-4 may also be different.

[0061] For example, the mass fraction difference of nitrogen in two adjacent layers of the membrane to be tested can be made approximately the same by controlling the reaction time and the ratio of nitrogen source, with the difference ranging from, for example, greater than or equal to 0.2% to less than 2%. Optionally, the mass fraction difference of nitrogen in two adjacent layers of the membrane to be tested can also range from, for example, greater than or equal to 0.5% to less than or equal to 1%. Optionally, the mass fraction difference of nitrogen in two adjacent layers of the membrane to be tested can also be different.

[0062] For example, after forming each layer of the membrane to be tested and before forming the next layer, the content of the target element contained in each layer of the membrane to be tested can be measured using the same standard device 110, thereby obtaining the nitrogen content or elemental distribution of each layer of the multilayer membrane to be tested. In some examples, in order to minimize the oxidative effect of oxygen in the air on each layer of the multilayer membrane to be tested, the time for measuring the content of the target element contained in each layer of the multilayer membrane to be tested is controlled to ≤1 hour. Alternatively, the time for measuring the content of the target element contained in each of the four layers of the membrane to be tested using the standard device 110 is controlled to <30 minutes. For example, in order to reduce the influence of the external environment on the differences caused by the multiple measurements and to improve the accuracy of the measurement, the time for the multiple measurements can be controlled to be the same.

[0063] It should be understood that, Figure 3 The four-layer test film shown is merely an example; multiple layers of test film with more than four layers can be formed as needed, and this application does not limit this.

[0064] In some examples, the measurement accuracy of the standard device 110 for the nitrogen content of each layer of the multilayer test film is, for example, greater than or equal to 0.2% and less than 2%. Optionally, the measurement accuracy of the standard device 110 for the nitrogen content of each layer of the multilayer test film may also be, for example, greater than or equal to 0.5% and less than or equal to 1%.

[0065] Because data acquisition using XPS equipment excites electrons in the film being tested without damaging its elemental structure, the measured data is relatively accurate and does not affect surrounding elements or elements in the underlying layers. This allows for the acquisition of elemental structure information for relatively thick films.

[0066] In some examples, such as Figure 4 As shown, after forming four layers of film to be tested, a protective layer 104 can be formed on the film layers 103-4 using thin film deposition processes such as CVD, PVD, ALD, and any combination thereof, to form a protective layer 104 as shown. Figure 4The standard sample 100 is shown. Optionally, the surfaces of the protective layer 104 and the films 103-4 to be tested that are in contact with each other may have the same dimensions (i.e., the surfaces in contact have the same width and length), thereby allowing the protective layer 104 to reduce damage to the films to be tested caused by changing the sample stage. Exemplarily, the thickness of the protective layer 104 is, for example, 1 nm to 30 nm; alternatively, the thickness of the protective layer 104 is approximately 10 nm, and the material used to protect 104 includes, for example, polycrystalline silicon. In some examples, after forming the standard sample 100, a sample of a predetermined size can be cut from the standard sample 100 as the sample to be tested. Exemplarily, a sample with a width ranging from 1 cm to 2 cm and including the aforementioned multiple layers of films to be tested can be cut from the standard sample 100 as the sample to be tested. Optionally, the size of the sample to be tested is approximately 1.5 cm × 1.5 cm. This 1.5 cm × 1.5 cm sample to be tested can be used for the second measurement described below. For example, in order to calibrate the measuring device 120 described below multiple times, a standard sample 100 of 1.5cm × 1.5cm size can be cut multiple times for a second measurement.

[0067] In other examples of performing a first measurement of the content of the target element contained in each layer of the multilayer test film using a standard apparatus, an insulating layer 102 may be formed on a substrate 101, and multiple test films (e.g., test films 103-1 to 103-4) may be sequentially formed on the insulating layer 102. Alternatively, after forming the multilayer test films, a first measurement of the content of the target element (e.g., nitrogen) contained in each layer of the multilayer test films may be performed using a standard apparatus different from the Inline XPS apparatus. This application does not limit the specific method of the first measurement.

[0068] In some cases, high-precision inline XPS systems are typically only capable of surface measurements and are not equipped with etching equipment (e.g., ion beam sputtering equipment), which often limits their application in the diverse processing of standard sample 100 and in the volumetric measurement of the elemental structure of standard sample 100.

[0069] Some embodiments of this application can accurately measure the minute differences (e.g., mass fraction variation range of greater than or equal to 0.2% and less than 2%) in the content of the target element contained in each layer of the multilayer film to be tested using a high-precision measuring device (e.g., an Inline XPS device) to obtain standard values, thereby enabling the preparation of a standard sample 100 based on the multilayer film to be tested. In subsequent research and production processes, this standard sample 100 can be processed in various ways to meet different needs. For example, the test sample formed using this standard sample 100 can be used to calibrate laboratory equipment (e.g., the Lab XPS device hereinafter) to meet research and development needs, or to calibrate equipment capable of volumetric measurement (e.g., the EELS device hereinafter) to improve the measurement accuracy of the aforementioned equipment.

[0070] Continue to refer to Figure 1 The calibration method 300 further includes step S320, which involves using a measuring device to perform a second measurement on the content of the target element contained in each layer of the multilayer film to be tested. (Reference) Figure 5 In some examples, the aforementioned sample to be tested can be used to calibrate a measuring device 120 with low measurement accuracy (accuracy range, for example, 2% to 10%) in the laboratory or on the production line. Exemplarily, the measuring device 120 includes, for example, a Lab XPS device with an accuracy range of, for example, 2% to 5%, a Secondary Ion Mass Spectrometry (SIMS) device with an accuracy range of 2% to 10%, and an EELS device for volume measurements with an accuracy range of 2% to 10%.

[0071] Alternatively, the aforementioned measuring device 120 can be used to perform a second measurement on each layer of the multilayer film to be tested in the sample (e.g., film layers 103-1 to 103-4) to obtain a measured value of the nitrogen content of each layer of the multilayer film to be tested. Lab XPS or SIMS equipment typically incorporates etching equipment (e.g., ion beam sputtering equipment), thus enabling etching and measurement to be performed on the same instrument. Optionally, the protective layer 104 and each layer of the multilayer film to be tested (e.g., film layers 103-1 to 103-4) can be etched and removed sequentially, and the nitrogen content of the next exposed film layer after each etching can be measured. By performing multiple etching operations and measuring the nitrogen content after each etching, nitrogen content data for each layer can be obtained.

[0072] Optionally, refer to Figure 5 and Figure 6 In the example where a Lab XPS device is used as the measuring device 120 for the second measurement, the protective layer 104 can be removed (see reference). Figure 4The process involves exposing the test film 103-4, the layer of multiple test films closest to the Lab XPS equipment, and then using the Lab XPS equipment to measure the content of the target element contained in test film 103-4 to obtain a measured value of the content of the target element contained in that layer. After measuring test film 103-4, test film 103-4 can be removed to expose the next layer of multiple test films (e.g., test film 103-3), and then the content of the target element contained in test film 103-3 can be measured to obtain a measured value of the content of the target element contained in that layer. The above operation can be repeated until the second measurement of each layer of multiple test films is completed and multiple measurement values ​​are obtained.

[0073] In some examples where the second measuring device 120 includes a Lab XPS device, an ion beam can be used to sequentially remove the protective layer 104 and each layer of the multilayer film to be tested from the sample under test. The thickness of each layer to be tested removed can be controlled by controlling the ion beam energy. Exemplarily, the ion beam includes at least one of argon ion beams, helium ion beams, and cesium ion beams. Optionally, a certain raster size can be set for the ion beam to determine the scanning range of the ion beam and thus the size of the etching area. Exemplarily, in the above-described etching process using an ion beam, the ion beam energy can be set to 300 eV, and the raster size can be set to 2.0 mm, so that for a 1.5 cm × 1.5 cm portion of the wafer, it takes approximately 7 seconds to complete one etching of the film to be tested.

[0074] In the example of using a SIMS device as the measuring device 120 for the second measurement, after exposing each layer of the film to be tested, the surface of each layer in the sample can be bombarded with a high-energy primary ion beam, causing the molecules on the surface of the film to absorb energy and sputter to generate secondary ions. Optionally, the aforementioned SIMS device can be, for example, a TOF SIMS (Time of Flight SIMS), which determines the mass of the secondary ions based on the different times it takes for the secondary ions to reach the detector due to their different masses. Based on the different masses of the secondary ions of different atoms, a spectrum of surface information about the film to be tested can be obtained, thereby enabling quantitative analysis of the film to be tested.

[0075] refer to Figure 7The nitrogen content of each film layer to be tested can be measured by combining TEM and EELS devices. The EELS device can utilize the inelastic scattering of the incident electron beam in the standard sample 100. The energy lost by the electrons directly reflects the scattering mechanism, the chemical composition of the standard sample 100, and the thickness, thereby analyzing the elemental composition, chemical bonds, and electronic structure of each micro-region of the thinner film layer to be tested.

[0076] In an example of combining TEM and EELS devices for a second measurement, the sample to be tested can be divided into multiple acquisition regions 105 along the thickness direction of the film to be tested, with the width of each acquisition region 105 being a step size. For example, as... Figure 7 As shown, all acquisition areas of sample 100 can be scanned from the same end along the column direction of the long arrow with a fixed step size. Each acquisition area can obtain an EELS spectrum containing the content information of the target element. The EELS spectra of all acquisition areas are integrated and superimposed to obtain the nitrogen content EELS spectrum of the membrane layer to be detected.

[0077] In some examples, the fixed step size range is, for example, from 0.5 nm to 1.22 nm. Exemplarily, by increasing the fixed step size, the irradiation damage of the incident electron beam to the sample 100 can be effectively reduced while maintaining the signal-to-background ratio (SBR), thereby improving the accuracy of nitrogen content measurement. Exemplarily, the fixed step size is, for example, 1.22 nm, which can reduce the influence of the incident electron beam on the sample 100.

[0078] Refer again Figure 1 The calibration method 300 continues to step S330, where the measuring device can be calibrated based on the results of the first and second measurements. In step S330, the measuring device (e.g., based on multiple standard values ​​obtained from the first measurement and multiple measurement values ​​obtained from the second measurement) can be calibrated according to multiple measurement values ​​obtained from the second measurement. Figure 5 or Figure 7 The measuring device 120 shown is calibrated to improve the accuracy of measuring the content of the target element. In some examples, multiple measurements can be fitted to multiple standard values, and the measuring device 120 can be calibrated based on the results of the fitting analysis.

[0079] For example, standard devices (e.g., Figure 2The standard device 110 and the measuring device 120 can obtain spectra of each layer of the film to be tested, showing minute variations in the content of the target element (e.g., nitrogen). Exemplarily, the standard device 110 is, for example, the Inline XPS device described above, which performs a first measurement on the content of the target element contained in each layer of the multilayer film to be tested to obtain an XPS spectrum; the measuring device 120 is, for example, the EELS device described above, which obtains an EELS spectrum. Optionally, the corresponding nitrogen content can be determined based on the XPS spectrum and the EELS spectrum. In some examples, the standard value and measured value of the nitrogen content determined from the XPS spectrum and the EELS spectrum can be fitted and analyzed, and the measuring device 120 can be calibrated based on the results of the fitting analysis.

[0080] In some examples, the above fitting analysis can be a linear fitting analysis, thus yielding a linear regression equation. If the regression coefficient R of the linear regression equation is... 2 If the result of the second measurement is greater than or equal to the preset value, then the result is considered accurate. Optionally, the upper regression coefficient R... 2 The preset value range is, for example, 85% to 90%. If R... 2 If the value is less than the preset value, the equipment parameters in the measuring device 120 need to be adjusted.

[0081] In some examples, after adjusting the equipment parameters, a standard sample of 100 cm × 1.5 cm can be cut again. A second measurement is then performed on the cut sample, and the result of the second measurement is linearly fitted to the result of the first measurement. If the fitted R... 2 If the result is less than 90%, the parameters of the measuring device 120 should be readjusted. Multiple sample selections, measurements, fittings, and parameter adjustments can be performed until R0 is reached. 2 Greater than 90%. The above-mentioned calibrated measuring device 120 can accurately measure the change in the mass fraction of nitrogen in the membrane layer between 0.2% and 2%.

[0082] Figure 8 and Figure 9 The graphs obtained by measuring the elemental distribution in each film layer of the sample under test using calibrated Lab XPS and TEM-EELS instruments are shown respectively. Figure 8 and Figure 9 In the graph, the horizontal axis represents the depth of each test layer within the standard sample 100, and the vertical axis represents the mass fraction of the element in each test layer. Figure 8 and Figure 9 It can be seen that the calibrated Lab XPS or TEM-EELS equipment can accurately measure the nitrogen content of the membrane layer with variations of 0.5% to 1%.

[0083] Figure 10 The diagram shows a linear fit between measurements obtained by the Lab XPS and TOF SIMS devices after multiple calibrations and standard values ​​measured by the Inline XPS device. Figure 10 It can be seen that the regression coefficient R0 of the linear fit between the measurement results of the calibrated Lab XPS and TOF SIMS devices and the measurement results of the Inline XPS device is... 2 Over 90%. Can be as high as 99% or more.

[0084] It should be understood that the above calibration method takes nitrogen as an example as the target element. In the film layer to be tested, in addition to nitrogen, silicon and oxygen are also included. The measuring device can be calibrated by the same or similar measurement and calibration method as that for nitrogen, so that minute changes in silicon or oxygen can be accurately measured. This application does not limit the type of target element.

[0085] In one embodiment of this application, the standard apparatus includes an X-ray photoelectron spectrometer with a measurement accuracy of ≤2%, and the measuring apparatus includes at least one of a secondary ion mass spectrometer, a transmission electron microscope-electron energy loss spectrometer, and an X-ray photoelectron spectrometer with a measurement accuracy of >2%.

[0086] In some examples, the computer platform can determine the nitrogen content of each layer of the multilayer film to be tested based on the spectra obtained from the first and second measurements, such as XPS or EELS spectra. Exemplarily, the computer platform can also perform a fitting analysis on the measured value of nitrogen content obtained by the measuring device against a standard value of nitrogen content measured by a standard device. Exemplarily, the computer platform includes a computer device and computer software running on the computer device. Exemplarily, the computer device may include a memory and a processor. The memory is used to store instructions executable by the processor. The processor is used to execute the instructions to determine the nitrogen content based on the spectra obtained from the first and second measurements and to perform a fitting analysis on the measured value of nitrogen content obtained by the second measurement against a standard value of nitrogen content measured by a standard device.

[0087] In some embodiments, the computer device further includes a communication port, input / output devices, and an internal communication bus. The communication port handles data communication between the computer device and external devices. The input / output devices support input / output data streams between the computer device and other components. For example, input / output devices may include one or more of the following components: a keyboard, mouse, camera, monitor, scanner, touchscreen, handwriting input tablet, and microphone, or any combination thereof. Input / output devices can input various numerical data and various non-numerical data, such as graphics, images, and sound, into the computer device. The internal communication bus enables data communication between various components within the computer device.

[0088] Other embodiments of this application also provide a method 500 for preparing a standard sample for calibration, such as... Figure 11 As shown, the preparation method 500 includes: S510, forming multiple layers of films containing target elements on a substrate, wherein the content of the target element contained in each layer varies in the same trend in the thickness direction of the multiple layers of films.

[0089] refer to Figure 12 For example, the substrate 101 may be a bare wafer with a diameter (at its maximum width) ranging from 10 cm to 20 cm. Optionally, the thickness of the insulating layer 102 may be, for example, 1 nm to 30 nm. Alternatively, the thickness of the insulating layer 102 may be approximately 10 nm.

[0090] In some examples, the material used for substrate 101 may include silicon (such as single-crystal silicon, polycrystalline silicon), silicon-germanium (SiGe), germanium (Ge), silicon-on-insulator (SOI), germanium-on-insulator (GOI), gallium arsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC), glass, III-V compound semiconductors, or any combination thereof. Optionally, the material used for insulating layer 102 may include, for example, silicon oxide.

[0091] refer to Figure 13 In some examples, multiple layers of films to be tested (e.g., films to be tested 301-1 to films to be tested 301-4) can be formed on substrate 101 using thin film deposition processes such as CVD, PVD, ALD, or any combination thereof. Return to Figure 12 Optionally, before forming the multilayer film to be tested, an insulating layer 102 may be formed on the substrate 101 by a thin film deposition process such as CVD, PVD, ALD, or any combination thereof. The insulating layer 102 may serve as the interface layer between the substrate 101 and the film to be tested 103-1. (Continue to the previous section) Figure 13In some examples including the insulating layer 102, multiple layers of films to be tested (e.g., films to be tested 103-1 to 103-4) can be formed on the insulating layer 102 using thin film deposition processes such as CVD, PVD, ALD, or any combination thereof. Optionally, the thickness of each film to be tested is, for example, 1 nm to 30 nm. Alternatively, the thickness of the insulating layer 102 can be approximately the same as the thickness of the film to be tested 103-1. Alternatively, the thickness of the insulating layer 120 can be different from the thickness of the film to be tested 103-1.

[0092] In some examples, to make the quality of the test film more closely resemble the ONO stack structure included in the channel structure of 3D NAND, atomic layer deposition (ALD) can be used to deposit silicon oxynitride multiple times on the insulating layer 102 as a multilayer test film. In some examples, the target element included in the test film is, for example, nitrogen. By controlling the deposition process time and gas source ratio, the thickness and nitrogen content of each layer of the formed multilayer test film can be made close to the thickness and nitrogen content of the electron trapping layer and tunneling layer in the ONO structure.

[0093] In an exemplary process for forming the test films using a deposition process, the nitrogen content in each layer of the multilayer test film can be adjusted by controlling the proportion of each reaction source. For example, the mass fraction of nitrogen in each layer of the formed multilayer test film can be controlled to increase in the direction of increasing film thickness by sequentially increasing the partial pressure of the nitrogen source in the reaction gas source. Optionally, in some cases, the mass fraction of nitrogen in each layer of the formed multilayer test film can be controlled to decrease in the direction of increasing film thickness by sequentially decreasing the partial pressure of the nitrogen source in the reaction gas source. Optionally, the mass fraction of nitrogen content in each test film layer is, for example, 10% to 40%. In some examples, the mass fraction of nitrogen content in each test film layer is, for example, 25% to 30%.

[0094] For example, the deposition process can be simplified by controlling the deposition time and deposition rate so that the thicknesses of the layers in the films to be tested 301-1 to 301-4 are approximately the same. Alternatively, the thicknesses of the layers in the films to be tested 301-1 to 301-4 may also be different.

[0095] For example, the mass fraction difference of nitrogen in two adjacent layers of the membrane to be tested can be made approximately the same by controlling the reaction time and the ratio of nitrogen source. The range of this difference is, for example, 0.2% to 2%. Optionally, the range of the mass fraction difference of nitrogen in two adjacent layers of the membrane to be tested can also be, for example, 0.2% to 1%. Optionally, the mass fraction difference of nitrogen in two adjacent layers of the membrane to be tested can also be different.

[0096] It should be understood that after each layer of the film to be tested is formed, the elemental content and distribution of that layer can be measured in the same way (e.g., the first measurement mentioned above) to obtain standard data on the depth-content of each layer of the multilayer film to be tested as a reference and calibration basis for subsequent measurements (e.g., the second measurement mentioned above).

[0097] Continue to refer to Figure 11 Method 500 further includes step S520, which involves forming a protective layer on a multilayer film to be tested to form a standard sample. Exemplarily, in forming such a... Figure 13 After the multilayer film to be tested shown, a protective layer 104 can be formed on the film layer 103-4 through thin film deposition processes such as CVD, PVD, ALD, and any combination thereof, to form a protective layer 104 as shown. Figure 4 The standard sample 100 is shown.

[0098] For example, the thickness of the protective layer 104 is, for example, 1 nm to 30 nm. Alternatively, the thickness of the protective layer 104 is approximately 10 nm, and the material used to protect 104 includes, for example, polycrystalline silicon. In some examples, after forming the standard sample 100 described above, a sample of a predetermined size can be cut from the standard sample 100 as a sample to be tested. For example, a sample with a width ranging from 1 cm to 2 cm and including the aforementioned multilayer test film can be cut from the standard sample 100 as a sample to be tested. Optionally, the size of the sample to be tested is approximately 1.5 cm × 1.5 cm. This 1.5 cm × 1.5 cm sample to be tested can be used as a sample for subsequent measurements (e.g., the second measurement mentioned above) and calibration.

[0099] It should be understood that the method for forming the standard sample 100 involved in the above calibration method 300 can be partially or completely applied to the method for preparing the standard sample described in method 500. Therefore, the contents that are the same as or similar to the structure and formation method of the above standard sample 100 will not be repeated in method 500.

[0100] The preparation method of some embodiments of this application can produce a standard sample containing multiple layers of film to be tested, and make the content of the target element in each layer of the multiple layers of film to be tested vary slightly (e.g., the mass fraction varies within a range of greater than or equal to 0.2% and less than 2%), so that the standard sample can be used to calibrate the measuring device mentioned above to improve the measurement accuracy of the measuring device.

[0101] Other embodiments of this application also provide a standard sample. It should be understood that the standard sample 100 involved in the above calibration method 300 ( Figure 4The contents of the substrate 101, insulating layer 102, each layer of the multilayer test film (e.g., test film 103-1 to test film 103-2) and protective layer 104 may be applied in part or in whole to the standard sample described herein.

[0102] Back Figure 4 In standard sample 100, substrate 101 may be, for example, a bare wafer with a diameter (at its maximum width) ranging from 10 cm to 20 cm. In some examples, the material used for substrate 101 may include silicon (such as single-crystal silicon, polycrystalline silicon), silicon-germanium (SiGe), germanium (Ge), silicon-on-insulator (SOI), germanium-on-insulator (GOI), gallium arsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC), glass, III-V compound semiconductors, or any combination thereof.

[0103] Optionally, in the example including the insulating layer 102, the insulating layer 102 may serve as the interface layer between the substrate 101 and the multilayer film to be tested. The thickness of the insulating layer 102 is, for example, 1 nm to 30 nm. Alternatively, the thickness of the insulating layer 102 is approximately 10 nm. Optionally, the material used for the insulating layer 102 may include, for example, silicon oxide.

[0104] Continue to refer to Figure 4 The standard sample 100, for example, comprises four layers of film to be tested (film layers 103-1 to 103-4). The nitrogen content of each layer in film layers 103-1 to 103-4 varies with the same trend along the thickness direction of the standard sample 100, and the difference in the content of the target element in adjacent film layers is greater than or equal to 0.2% and less than 2%. Optionally, the thickness of the film layers to be tested is, for example, 1 nm to 30 nm. Optionally, each layer of the multilayer film to be tested may have the same thickness or different thicknesses. For example, the thickness of each film layer to be tested is approximately 20 nm.

[0105] It should be understood that, Figure 4 The four layers of the test film shown are merely an example. The standard sample 100 may be configured with more than four layers of multilayer test film as needed, and this application does not limit this.

[0106] In some examples, the thickness and nitrogen content of each layer of the multilayer test film can be close to the thickness and nitrogen content of the electron trapping layer and tunneling layer in the ONO structure. Optionally, the mass fraction of nitrogen in each layer of the multilayer test film can increase in the direction of increasing thickness. In some cases, the mass fraction of nitrogen in each layer of the multilayer test film can decrease in the direction of increasing thickness. Optionally, the mass fraction of nitrogen in each test film layer is, for example, 10% to 40%. In some examples, the mass fraction of nitrogen in each test film layer is, for example, 25% to 30%. Exemplarily, the mass fraction difference of nitrogen in adjacent test film layers can be made approximately the same by controlling the reaction time and the ratio of nitrogen source, with the difference ranging from, for example, 0.2% to 2%. Optionally, the mass fraction difference of nitrogen in adjacent test film layers can also range from, for example, 0.2% to 1%. Optionally, the mass fraction difference of nitrogen in adjacent test film layers can also be different.

[0107] For example, in the standard sample 100, the thickness of the protective layer 104 is, for example, 1 nm to 30 nm. Alternatively, the thickness of the protective layer 104 is approximately 10 nm, and the material used to protect 104 includes, for example, polycrystalline silicon. In some examples, a sample of a predetermined size can be cut from the standard sample 100 as the sample to be tested. For example, a sample with a width ranging from 1 cm to 2 cm and including the aforementioned multilayer test films can be cut from the standard sample 100 as the sample to be tested. Optionally, the size of the sample to be tested is approximately 1.5 cm × 1.5 cm. This 1.5 cm × 1.5 cm sample to be tested (e.g., the sample used for the second measurement and calibration mentioned above). In some embodiments of this application, the standard sample may include multiple layers of test films, wherein the target element content of each layer in the multiple layers of test films has slight variations (e.g., the mass fraction variation ranges from greater than or equal to 0.2% to less than 2%), so that the standard sample can be used to calibrate the measuring device mentioned above to improve the measurement accuracy of the measuring device.

[0108] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. Calibration methods for measuring devices, including: A film layer to be tested is formed, and the content of the target element contained in the film layer to be tested is measured using a standard device; Repeat the formation steps until multiple layers of the film to be tested are formed, and use a standard device to perform a first measurement on the content of the target element contained in each layer of the multiple layers of the film to be tested, wherein the content of the target element contained in each layer of the multiple layers of the film to be tested varies in the same trend in the thickness direction of the multiple layers of the film to be tested. A standard sample comprising the multilayer film to be tested is formed; A sample of a predetermined size, including the multilayer film to be tested, is cut from the standard sample as the sample to be tested. The measuring device is used to perform a second measurement on the content of the target element contained in each layer of the multilayer film to be tested; and The measuring device is calibrated based on the results of the first and second measurements.

2. The method according to claim 1, wherein, The second measurement of the content of the target element contained in each layer of the multilayer film to be tested using the measuring device includes: b1) The content of the target element contained in one of the multilayer membrane layers of the sample to be tested, which is located closer to the measuring device, is measured using the measuring device. b2) Remove one layer of the multilayer film to be tested that is closest to the measuring device to expose the next layer of the multilayer film to be tested; b3) Measure the content of the target element contained in the next layer of the multilayer test film; and b4) Repeat steps b2) and b3) until the second measurement is completed.

3. The method according to claim 1, wherein, The sample to be tested includes multiple collection areas divided along the thickness direction of the film layer to be tested. The second measurement of the content of the target element contained in each layer of the multilayer film layer to be tested using the measuring device includes: Electron beam scanning is performed sequentially on multiple acquisition areas to obtain multiple spectra containing the content information of the target element; and The spectra from the multiple acquisition areas are superimposed to complete the second measurement.

4. The method according to claim 1, wherein, Calibrling the measuring device based on the results of the first and second measurements includes: The multiple standard values ​​obtained from the first measurement are linearly fitted to the multiple measurement values ​​obtained from the second measurement; and In response to the regression coefficient after linear fitting being less than a preset value, the measuring device is calibrated.

5. The method according to claim 1, wherein, The difference in the content of the target element contained in adjacent membrane layers to be tested is greater than or equal to 0.2% and less than 2%.

6. The method according to claim 1, wherein, The standard apparatus is used to measure the target elements contained in each layer of the multilayer film to be tested at the same time.

7. The method according to claim 1, wherein, The time required to measure the target elements contained in each layer of the multilayer film to be tested using the standard device is ≤1 hour.

8. The method according to claim 1, wherein, Each layer of the multilayer film to be tested contains silicon oxynitride, and the target element includes at least one of nitrogen, silicon, or oxygen.

9. The method according to claim 1, wherein, The standard sample comprising the multilayer film to be tested includes: Multiple layers of a target element are formed on a substrate, wherein the content of the target element in each layer of the multiple layers varies with the same trend along the thickness direction of the multiple layers of the target film; and A protective layer is formed on the multiple layers of the film to be tested to form the standard sample.

10. The method according to claim 9, wherein, The method further includes: An insulating layer is formed on the substrate before the formation of multiple layers of the film to be tested.

11. The method according to claim 10, wherein, The difference in the content of the target element contained in adjacent membrane layers to be tested is greater than or equal to 0.2% and less than 2%.

12. The method according to claim 1, wherein, The standard samples include: Substrate; A multilayer film to be tested is located on the substrate, wherein the content of the target element contained in each layer of the multilayer film to be tested varies with the same trend in the thickness direction of the multilayer film to be tested; and A protective layer located on the multilayer film to be tested.

13. The method according to claim 12, wherein, The standard sample also includes: An insulating layer is located between the substrate and the multilayer film to be tested.

14. The method according to claim 13, wherein, The content of the target element contained in each layer of the multilayer test film varies in an increasing trend in the direction of increasing thickness of the multilayer test film.

15. The method according to claim 13, wherein, The content of the target element contained in each layer of the multilayer test film changes in a decreasing trend in the direction of increasing thickness of the multilayer test film.

16. The method according to claim 12, wherein, The difference in the content of the target element contained in adjacent membrane layers to be tested is greater than or equal to 0.2% and less than 2%.

17. The method according to claim 12, wherein, The film to be tested includes silicon oxynitride, and the target element includes at least one of nitrogen, silicon, or oxygen.

18. The method according to claim 13, wherein, The insulating layer comprises silicon oxide, and the protective layer comprises polycrystalline silicon.

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