A sample preparation method

Abstract

The embodiment of the present application provides a sample preparation method, comprising: providing a sample to be detected; determining a detection area to be detected in the sample to be detected and a pretreatment area located around the detection area to be detected, wherein the pretreatment area is in a circular ring type, and the diameter of the inner ring is a first preset diameter; etching the pretreatment area to a first preset depth; filling a first protective material in the pretreatment area and not lower than the upper surface of the detection area to be detected; and pretreating the pretreatment area and the detection area to be detected to obtain a first pretreatment sample.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and is related to, but not limited to, a sample preparation method. Background Art

[0002] Three-dimensional atom probe tomography (APT) is a measurement and analysis method with atomic-level spatial resolution. When performing three-dimensional atom probe measurements, the diameter of the sample needs to be small enough so that the atoms in the sample can be induced to evaporate at a relatively low voltage, thereby enabling the detection atoms in the sample to be measured. During detection, the sample is connected to a positive high voltage as an anode, and the atoms at the top of the sample are in a state to be ionized. When a pulse voltage or pulse laser is superimposed on the top of the sample, the surface atoms will be ionized and evaporated, that is, the element is precipitated. The mass-to-charge ratio of the evaporated ions is measured using a time-of-flight mass spectrometer to obtain the mass spectrum peak of the ion to determine the elemental type of the evaporated ion. The two-dimensional coordinates of the flying ions on the surface of the sample top are recorded using a position-sensitive probe. The longitudinal coordinates of the ions are determined by the layer-by-layer accumulation of the ions in the longitudinal direction, thereby generating a three-dimensional spatial distribution image of different types of atoms in the sample.

[0003] The storage capacitor in the dynamic random access memory (DRAM) includes an upper electrode layer, a lower electrode layer and a dielectric layer. In the related art, the dielectric layer is usually doped with elements such as silicon (Si) to increase the dielectric constant of the dielectric layer, thereby increasing the capacitance of the storage capacitor. The three-dimensional atom probe is used to measure the concentration and distribution of the doping elements in the dielectric layer to determine the doping effect. Since the diameter of the storage capacitor is very small, the distance between each two storage capacitors is very close, and there are multiple layers of different materials between each two dielectric layers, when using a focused ion beam (FIB) to prepare a three-dimensional atom probe test sample, it is difficult to perform uniform ring cutting during sample preparation due to the influence of factors such as the atomic binding energy, atomic weight and crystal structure of multiple layers of different materials. This makes the sample surface very rough and even produces burrs, resulting in secondary tips during the experiment, affecting the measurement results. Summary of the Invention

[0004] In view of this, an embodiment of the present application provides a sample preparation method.

[0005] An embodiment of the present application provides a sample preparation method, including: providing a sample to be detected; determining an area to be detected in the sample to be detected and a pretreatment area located around the area to be detected, wherein the pretreatment area is in a circular ring shape, and the diameter of the inner ring is a first preset diameter; etching the pretreatment area to a first preset depth; filling the pretreatment area with a first protective material that is not lower than the upper surface of the area to be detected; and pretreating the pretreatment area and the area to be detected to obtain a first pretreated sample.

[0006] In an embodiment of the present application, a first pretreated sample comprising the first protective material and the area to be detected is obtained by etching a pretreated area around the area to be detected in the sample to be detected and filling the pretreated area with a first protective material. Since the diameter of the ring in the pretreated area is the first preset diameter, when the sample to be detected is a semiconductor device including a capacitor column, the circle with the first preset diameter can cover the capacitor column in the area to be detected, and will not include other capacitor columns. While achieving the first protective material in the first pretreated sample being able to surround the capacitor column in the area to be detected, it is convenient to perform ring cutting in the single layer where the first protective material is located, while reducing the influence of other capacitor columns on the detection results of the capacitor columns in the area to be detected, thereby solving the problem of difficulty in uniform ring cutting during sample preparation due to the influence of factors such as the atomic binding energy, atomic weight and crystal structure of multiple layers of different materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In the accompanying drawings (which are not necessarily drawn to scale), like reference numerals may describe similar components in different views. Like reference numerals with different letter suffixes may represent different examples of similar components. The accompanying drawings generally illustrate various embodiments discussed herein by way of example and not limitation.

[0008] Figure 1A A schematic diagram of a sample preparation method provided in an embodiment of the present application;

[0009] Figure 1B A schematic cross-sectional view of a columnar capacitor provided in an embodiment of the present application;

[0010] Figure 1C A schematic cross-sectional view of a double-sided capacitor provided in an embodiment of the present application;

[0011] Figure 1D A top view of a columnar capacitor provided in an embodiment of the present application;

[0012] Figures 1E to 2H A schematic diagram of a process for forming a first pre-treated sample provided in an embodiment of the present application;

[0013] Figures 3A to 3CA schematic diagram of a process for forming a first final measurement sample provided in an embodiment of the present application.

[0014] The following are the descriptions of the reference numerals:

[0015] 101—upper electrode layer; 103—dielectric layer; 102—lower electrode layer; 104—pretreatment area; 105—first protective material; 109—first upper electrode layer; 110—first dielectric layer; 106—lower electrode layer; 107—second dielectric layer; 108—second upper electrode layer; 10—capacitor column; 20—Si or GeSi layer; d2—outer ring diameter of the pretreatment area; d1—inner ring diameter of the pretreatment area; 30—sample to be tested; 201—protection area; 202—in-situ nanomanipulator; 203—protective layer and conductive layer; 204—first pretreatment sample; 2041—preset area; 205—etched portion; 301—silicon substrate; 303—first intermediate measurement sample; 304—second pretreatment sample; 305—first final measurement sample. DETAILED DESCRIPTION

[0016] The exemplary embodiments disclosed herein will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the specific embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0017] In the following description, numerous specific details are provided to provide a more thorough understanding of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced without one or more of these details. In other instances, certain technical features known in the art are not described to avoid confusion with the present application; that is, all features of actual embodiments are not described herein, nor are well-known functions and structures described in detail.

[0018] In the drawings, the sizes of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0019] It should be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer, or part discussed below may be represented as a second element, component, region, layer, or part. And when the second element, component, region, layer, or part is discussed, it does not necessarily mean that the first element, component, region, layer, or part is present in the present application.

[0020] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present application. When used herein, the singular forms "a", "an", and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0021] The present invention provides a sample preparation method. Figure 1A As shown, the method includes:

[0022] Step S102: providing a sample to be tested;

[0023] Here, the sample to be tested can be a sample containing doped elements, such as an active region or a low-doped region in a semiconductor device; or it can be a sample not containing doped elements, for example, a sample to be tested that includes an area to be tested (such as a welding area, a riveted area, a diffusion area, etc.). The embodiments of the present application do not limit the type of sample to be tested.

[0024] In some embodiments, the sample to be detected may be a semiconductor device including a capacitor column, such as a DRAM, a static random access memory (SRAM), etc.

[0025] Taking DRAM as an example, DRAM is a semiconductor memory, usually arranged in a two-dimensional matrix with a storage capacitor and a transistor as a unit. The storage capacitor is used to store data. If there is a charge on the storage capacitor, it means that the storage unit stores 1, otherwise it stores 0, realizing data access; the transistor acts as a switch, allowing and prohibiting operations on the storage capacitor.

[0026] Generally speaking, storage capacitors in DRAM are divided into columnar capacitors and double-sided capacitors. The center of a columnar capacitor or a double-sided capacitor is generally a gap. The sample to be tested in the embodiment of the present application can be a columnar capacitor or a double-sided capacitor.

[0027] Figure 1B A cross-sectional diagram of a columnar capacitor is shown. Figure 1B It can be seen that the columnar capacitor includes a lower electrode layer 102, a dielectric layer 103, and an upper electrode layer 101 from the inside out;

[0028] The materials of the upper electrode layer and the lower electrode layer can be titanium nitride (TiN), and the dielectric layer is generally made of a material with a high dielectric constant k, such as hafnium oxide (Hf x O y ), zirconium oxide (Zr x O y ) and aluminum oxide (Al x O y ) etc. In some embodiments, the high-k dielectric layer is at least one of the following: HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, ZrO2 or Al2O3.

[0029] Figure 1C A cross-sectional diagram of a double-sided capacitor is shown. Figure 1C It can be seen that the double-sided capacitor includes, from the inside out, a second top electrode layer 108 , a second dielectric layer 107 , a bottom electrode layer 106 , a first dielectric layer 110 and a first top electrode layer 109 .

[0030] The materials of the first upper electrode layer, the second upper electrode layer and the lower electrode layer can be TiN, and the first dielectric layer and the second dielectric layer are generally high-k materials, such as hafnium oxide (Hf x O y ), zirconium oxide (Zr x O y ), and aluminum oxide (Al x O y ) etc. In some embodiments, the high-k dielectric layer is at least one of the following: HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, ZrO2 or Al2O3.

[0031] Figure 1DA top view of a columnar capacitor is shown, wherein a DRAM includes a plurality of capacitor columns 10, and each capacitor column 10 includes an upper electrode layer 101, a lower electrode layer 102, and a dielectric layer 103 located between the upper electrode layer 101 and the lower electrode layer 102. In some embodiments, a Si or GeSi layer 20 is provided between the independent capacitor columns 10 for connecting the upper electrode layer 101. In some embodiments, the electrical connection between the upper electrode layer 101 and the metal layer can be achieved by providing a plug on the Si or GeSi layer to electrically connect to the metal layer. In some embodiments, in order to further improve the dielectric constant of the dielectric layer and increase the capacitance of the capacitor column, Si and other elements can be doped into the dielectric layer 103, and the content and position distribution of the doped elements in the dielectric layer are important factors affecting the dielectric constant of the dielectric layer. Therefore, it is necessary to detect the doped elements in the dielectric layer.

[0032] In order to detect the concentration and distribution of doping elements in the dielectric layer 103, it is necessary to prepare samples for three-dimensional atom probe testing and detect them with a three-dimensional atom probe. The samples used in the three-dimensional atom probe detection are needle-tip-shaped, and there are two main methods for preparing them. The first is electrochemical polishing, that is, polishing one end of a filamentous or thin strip sample to a needle-tip shape through an electrolyte, and the top diameter is less than 200 nanometers (nm). However, this method can only be applied to metal samples, and it is not possible to prepare samples in a fixed area for samples with specific microstructures (such as grain boundaries, phase boundaries, cracks, etc.). The second is a focused ion beam, which can accurately prepare samples for three-dimensional atom probes and solve the problems existing in electrochemical polishing. Therefore, a focused ion beam is usually used to prepare three-dimensional atom probe test samples.

[0033] A focused ion beam is an ion beam generated by an ion source (most focused ion beams use gallium (Ga) ion sources because of their low melting point, low vapor pressure, and good oxidation resistance. Some equipment also has helium (He) and neon (Ne) ion sources) that is accelerated by an ion gun and focused on the sample surface. Its main functions are: (1) generating secondary electron signals to obtain electron images; (2) using a high current ion beam to strip off surface atoms to complete micro- and nano-scale surface morphology processing; and (3) using physical sputtering combined with chemical gas reactions to selectively strip off metals, silicon oxide layers, or deposited metal layers.

[0034] In some embodiments, a focused ion beam can be coupled with a scanning electron microscope to form a FIB-SEM dual-input system, and then combined with corresponding gas deposition equipment, nanomanipulators, various detectors, controllable sample stages and other accessories to form an analytical instrument that integrates micro-area imaging, processing analysis, and manipulation.

[0035] Because the diameter of each capacitor column is very small, the distance between each two capacitor columns is very close, and there are multiple layers of different materials between each two dielectric layers (such as the upper electrode layer, Si or GeSi layer, second upper electrode layer, etc.), when using a focused ion beam to prepare a three-dimensional atomic probe test sample, it is difficult to perform uniform ring cutting during sample preparation due to the influence of factors such as the atomic binding energy, atomic weight and crystal structure of the multiple layers of different materials. This makes the sample surface very rough and even produces burrs, resulting in the appearance of secondary tips during the experiment, affecting the measurement results.

[0036] Step S104: determining a to-be-detected area in the to-be-detected sample and a pre-treated area located around the to-be-detected area, wherein the pre-treated area is annular, and the diameter of the inner ring thereof is equal to a first preset diameter;

[0037] Here, the area to be detected can be an area that needs to be detected (such as a welding area, a riveting area, a diffusion area, etc.), or it can be an area containing doping elements for detecting the concentration of doping elements. For example, when the sample to be detected is a semiconductor device including a capacitor column, the capacitor column including the doping element can be the area to be detected, that is, Figure 1D The capacitor column 10 is shown in FIG.

[0038] In some embodiments, since the sample of the three-dimensional atomic probe is conical, the pretreatment area can be in the shape of a ring. In this way, after the pretreatment area is subsequently filled with the first protective material to obtain the first pretreatment sample, the layer where the first protective material is located in the first pretreatment sample can be conveniently cut to obtain a conical sample.

[0039] In some embodiments, the diameter of the ring within the pre-treated area can be equal to a first predetermined diameter. The first predetermined diameter can be the minimum diameter of a circle with the first predetermined diameter that can encompass the area to be inspected. This allows the first protective material in the first pre-treated sample to surround the area to be inspected, facilitating subsequent ring cutting within a single layer of the first protective material.

[0040] like Figure 1EAs shown, in the case where the sample 30 to be detected is a semiconductor device including a capacitor column 10, the diameter d1 of the inner ring of the pretreatment area 104 is equal to the first preset diameter. The first preset diameter can be set according to the diameter of the capacitor column and the distance between the capacitor columns. For example, the distance between the capacitor columns is 0.5 times the diameter of the capacitor column, then the value range of the first preset diameter can be 1 to 1.5 times the diameter of the capacitor column 10, so that the circle with the first preset diameter can cover the capacitor columns in the area to be detected, and will not include other capacitor columns. While achieving the first protective material being able to surround the capacitor columns in the area to be detected, it is convenient to perform subsequent ring cutting in the single layer where the first protective material is located, while reducing the influence of other capacitor columns on the detection results of the capacitor columns in the area to be detected. In some embodiments, the diameter d2 of the outer ring of the pretreatment area 104 can be greater than the second preset diameter, wherein the second preset diameter can be 100 to 300 nm, for example, the second preset diameter can be 100 nm. When using a focused ion beam to prepare a three-dimensional atomic probe sample on a capacitor column, if there are multiple layers of material within a circle within 100 nm with the center of the capacitor column as the center, then when cutting a circle with a diameter less than 100 nm with the center of the capacitor column as the center, it will be affected by the multiple layers of material, resulting in uneven cutting.

[0041] When the diameter of the outer ring of the pretreatment area is greater than the second preset diameter of 100nm, and the diameter of the inner ring is equal to the diameter of the capacitor column, since the first protective material is subsequently filled in the pretreatment area, the pretreatment area within 100nm is a single layer with the first protective material, so that the single layer where the first protective material is located can be ring-cut, solving the problem of difficulty in uniform ring-cutting during the sample preparation process due to the influence of factors such as the atomic binding energy, atomic weight and crystal structure of multiple layers of different materials.

[0042] In some embodiments, the diameter d2 of the outer ring of the pretreatment region may be 300 to 500 nm, so that the pretreatment region has a certain width, which facilitates the focused ion beam to perform circular cutting in the pretreatment region.

[0043] In some embodiments, the pre-processing area may also be in other shapes, such as a U-shape, etc. The embodiment of the present application does not limit the shape of the pre-processing area.

[0044] In some embodiments, the implementation of step S104 may include:

[0045] S1041: Acquire an image of the sample to be detected;

[0046] Here, a camera can be used to capture images of the sample to be tested, and clear images of the sample to be tested can be obtained by adjusting parameters such as working distance, focal length, contrast, and brightness.

[0047] S1042: Determine the area to be detected in the sample to be detected in the image;

[0048] S1043: Based on the area to be detected, determine a pre-processing area located around the area to be detected.

[0049] Here, both step S1042 and step S1043 determine the area to be detected and the pre-processed area in the acquired image, which facilitates implementation and range determination.

[0050] In some embodiments, the focused ion beam can be used in conjunction with a scanning electron microscope (SEM) to observe in real time to determine the area to be inspected and the area to be pretreated.

[0051] Step S106: etching the pre-treated area to a first preset depth;

[0052] Here, a focused ion beam can be used to etch the pre-treated area to a first preset depth. Since the ions have a large mass, after being accelerated and focused, their kinetic energy is transferred to the atoms and molecules in the sample, generating a sputtering effect, thereby etching the material in the pre-treated area.

[0053] In some embodiments, the first preset depth may be determined based on the measurement depth. For example, since the height of a capacitor column is approximately 1 micron, the first preset depth may be 200 to 1000 nm to obtain the concentration and distribution of the doping element in the dielectric layer within a capacitor column.

[0054] Step S108: Filling the pre-processing area with a first protective material not lower than the upper surface of the area to be inspected;

[0055] Fill the pre-treated area with the first protective material 105 to obtain Figure 1F Here, the first protective material can be silicon dioxide. Since silicon dioxide is non-conductive, even if the prepared sample contains some silicon dioxide material, it will not affect the measurement results during the three-dimensional atom probe test.

[0056] In some embodiments, the first protective material may also be other non-metallic materials, such as aluminum oxide, manganese dioxide, etc. The embodiment of the present application does not limit the type of the first protective material.

[0057] In some embodiments, the filled first protective material may be no lower than the upper surface of the area to be inspected. In this way, all areas to be inspected can be within the protection range of the first protective material, reducing the risk of accidental cutting during ring cutting.

[0058] Here, a focused ion beam may be used to fill the first protective material. In some embodiments, a deposition process, such as chemical vapor deposition or atomic layer deposition, may also be used for filling.

[0059] Step S110: pre-treating the pre-treated area and the area to be detected to obtain a first pre-treated sample.

[0060] Here, the first pre-treated sample is a sample connected to the in-situ nanomanipulator and disconnected from the sample to be detected.

[0061] During implementation, the pre-treated sample can be prepared by combining a focused ion beam with a nanomanipulator accessory, wherein the nanomanipulator includes an in-situ nanomanipulator that can achieve three-dimensional manipulation at the atomic scale.

[0062] In some embodiments, the first pretreated sample can be obtained by welding the in-situ nanomanipulator to one end of the sample to be detected, and then cutting off the portion of the sample connected to the in-situ nanomanipulator from the other end of the sample to be detected.

[0063] In some embodiments, the weld metal may be platinum or tungsten.

[0064] In an embodiment of the present application, a first pretreated sample comprising the first protective material and the area to be detected is obtained by etching a pretreated area around the area to be detected in the sample to be detected and filling the pretreated area with a first protective material. Since the diameter of the ring in the pretreated area is the first preset diameter, when the sample to be detected is a semiconductor device including a capacitor column, the circle with the first preset diameter can cover the capacitor column in the area to be detected, and will not include other capacitor columns. While achieving the first protective material in the first pretreated sample being able to surround the capacitor column in the area to be detected, it is convenient to perform ring cutting in the single layer where the first protective material is located, while reducing the influence of other capacitor columns on the detection results of the capacitor columns in the area to be detected, thereby solving the problem of difficulty in uniform ring cutting during sample preparation due to the influence of factors such as the atomic binding energy, atomic weight and crystal structure of multiple layers of different materials.

[0065] In some embodiments, the implementation of step S110 of "pre-treating the pre-treated area and the area to be detected to obtain a first pre-treated sample" includes:

[0066] S1101: etching a peripheral area of ​​a protection zone to a second preset depth, wherein the protection zone is an area including at least a portion of the pre-processing zone and the area to be inspected;

[0067] like Figure 2BAs shown, the protection zone 201 may include a portion of the pre-processing area (ie, the area where the first protection material 105 is located) and an area to be detected (ie, the area of ​​the capacitor column 10). Figure 2A As shown, the protection zone 201 may also include other areas (ie, the area where part of the sample 30 to be detected is located) in addition to the pre-treatment area and the area to be detected.

[0068] It should be noted that the shape of the protected area Figure 2A and Figure 2B In addition to the rectangle shown, other shapes may include ellipse, trapezoid, circle, etc. The embodiment of the present application does not limit the shape of the protection zone.

[0069] In some embodiments, the shape of the periphery of the etching protection zone can be determined according to the shape of the protection zone. For example, etching can be performed along the boundary of the protection zone. During etching, a portion is retained to be connected to the sample to be tested, which plays a positioning role when the nano-manipulator is subsequently welded to the protection zone in situ.

[0070] by Figure 2A Taking the shape of the middle protection zone 201 as an example, the implementation of etching the peripheral area of ​​the protection zone can be: using FIB to etch along the three sides of the protection zone 201, wherein the three sides can be Figure 2A Mark the three edges A, B, and C in Figure 2C In the structure shown, the etched portion 205 disconnects the three sides A, B, and C of the protection zone 201 from the sample to be detected 30, leaving one side F connected to the sample to be detected 30. The embodiment of the present application does not limit which three sides are etched.

[0071] The second preset depth can be determined according to the depth to be tested. For example, if the depth to be tested is 200 nm, the second preset depth is 200 nm. It should be noted that the second preset depth can be the same as or different from the first preset depth.

[0072] S1102: Cutting off the connection between the protection zone and the sample to be detected at the second preset depth, leaving the first side connected to the sample to be detected, to obtain a cantilever structure;

[0073] like Figure 2D ( Figure 2A As shown in the corresponding front view, the FIB is used to cut off the connection between the protection zone 201 and the sample to be detected 30 at the second preset depth d4, and the first side D is kept connected to the sample to be detected 30, and the result is as shown in FIG. Figure 2D The cantilever structure shown.

[0074] S1103: welding the in-situ nano-manipulator to a second side of the protection zone opposite to the first side;

[0075] like Figure 2E ( Figure 2D As shown in the corresponding top view, the in-situ nano-manipulator 202 is welded to the second side E of the protection zone 201 opposite to the first side D.

[0076] During implementation, the in-situ nano-manipulator 202 is corrected to a suitable needle tip shape by a large current. The diameter of the needle tip can be set according to the size of the protection zone. For example, the diameter of the needle tip can be 20 nm.

[0077] S1104: Cutting off the first side and the sample to be detected to obtain the first pretreated sample.

[0078] like Figure 2E As shown, the first side D and the sample to be tested 30 are cut off to obtain Figure 2F The first pre-treated sample is shown.

[0079] In some embodiments, the implementation of step S1103 of “welding the in-situ nano-manipulator to a second side of the protection zone opposite to the first side” includes:

[0080] S1131: moving the tip of the in-situ nanomanipulator to above the second side in the protection zone;

[0081] When implementing, if Figure 2G As shown, the in-situ nanomanipulator 202 is moved to a position above the second side E of the protected area 201. The movement speed of the in-situ nanomanipulator 202 can be varied from fast to slow. When the in-situ nanomanipulator 202 approaches the position above the second side E of the protected area 201, the movement speed of the in-situ nanomanipulator 202 is reduced, for example, to 0.1 nm / s.

[0082] S1132: depositing welding metal onto the tip of the in-situ nanomanipulator to fill the gap between the in-situ nanomanipulator and the second side, so that the in-situ nanomanipulator is welded to the second side of the protection zone opposite to the first side.

[0083] Here, the welding metal can be deposited by utilizing the energy of the ion beam to stimulate a chemical reaction. During implementation, some metal organic matter is sprayed onto the area on the sample where deposition is required through a gas injection system. When the ion beam is focused on this area, the energy of the ion beam causes the organic matter to decompose. The decomposed metal solid components are deposited, while the volatile organic components are extracted by the vacuum system, thereby achieving the deposition of the welding metal.

[0084] In some embodiments, the field evaporation voltage of the deposited welding metal may be relatively small, such as tungsten or platinum. This facilitates the removal of the welding metal without affecting the testing of the sample to be tested.

[0085] In some embodiments, the deposition area of ​​the welding metal can be slightly larger than the diameter of the tip of the in-situ nanomanipulator, and the position can be slightly upward. The deposition can be performed 1 to 2 times to ensure that the thickness of the deposited layer of the welding metal can fill the gap between the in-situ nanomanipulator and the second side, thereby achieving welding of the in-situ nanomanipulator and the second side.

[0086] In some embodiments, as Figure 2H As shown, the implementation of step S110 "pre-treating the pre-treated area and the area to be detected to obtain a first pre-treated sample" may further include:

[0087] S110a: depositing a protective layer and a conductive layer in sequence on the upper surface of the protection zone; wherein the protection zone is an area including at least part of the pretreatment area and the area to be detected, the thickness of the protective layer is 100 to 200 nm, and the thickness of the conductive layer is 300 to 1000 nm.

[0088] like Figure 2H As shown in step (1), the sample 30 to be tested includes a protection zone 201. In step (2), a protective layer and a conductive layer are sequentially deposited on the upper surface of the protection zone 201. For the convenience of drawing, the protective layer and the conductive layer are collectively marked as 203.

[0089] In some embodiments, the protective layer may be made of ethyl silicate to protect the area to be inspected during the subsequent ring cutting process, thereby reducing the risk of accidentally cutting into the area to be inspected. In some embodiments, the conductive layer may be made of platinum to enhance the conductivity of the surface of the protected area, facilitating the subsequent etching process (i.e., step S110b) to extract the first pretreated sample.

[0090] In some embodiments, the conductive layer may be deposited using a process such as chemical vapor deposition or atomic layer deposition.

[0091] Regarding the thickness of the protective layer and the conductive layer, those skilled in the art can adjust them according to actual conditions, and the embodiments of the present application do not limit this.

[0092] S110b: etching the peripheral area of ​​the protection zone to a second preset depth;

[0093] Here, step S110b refers to step S1101.

[0094] like Figure 2HAs shown in step (3), the shape of the protection zone 201 is rectangular, and the three sides of the protection zone 201 are etched to a second preset depth. The etched portion 205 disconnects the three sides of the protection zone 201 from the sample to be detected 30, leaving one side connected to the sample to be detected 30.

[0095] S110c: cutting off the connection between the protection zone and the sample to be detected at the second preset depth, leaving the first side connected to the sample to be detected, to obtain a cantilever structure;

[0096] Here, step S110c refers to step S1102.

[0097] S110d: moving the tip of the in-situ nanomanipulator to above the second side in the protection zone;

[0098] Here, step S110d refers to step S1131. Figure 2H As shown in step (4) in , the tip of the in-situ nano-manipulator 202 is moved to above the second side E in the protection zone 201 .

[0099] S110e: depositing welding metal on the tip of the in-situ nanomanipulator to fill the gap between the in-situ nanomanipulator and the second side, so that the in-situ nanomanipulator is welded to the second side of the protection zone opposite to the first side;

[0100] Here, step S110e refers to step S1132. Figure 2H As shown in step (5) in FIG. 1 , welding metal is deposited onto the tip of the in-situ nano-manipulator 202 .

[0101] S110f: Cutting off the first side and the sample to be detected to obtain the first pretreated sample.

[0102] Here, step S110f refers to step S1104. Figure 2H The first side D shown in step (5) is connected to the sample 30 to be tested, and the result is as follows Figure 2H The first pre-treated sample 204 is shown in step (6).

[0103] The present application also provides a sample preparation method, such as Figure 3A As shown, the method includes:

[0104] Steps 301 to 305 correspond to steps S102 to S110 , respectively.

[0105] Step 306: Providing a silicon substrate;

[0106] like Figure 3A As shown in step (1), a silicon substrate 301 is provided;

[0107] Step 307: placing a predetermined area of ​​the first pre-treated sample away from one end of the in-situ nano-manipulator at a position of the circular opening of the silicon substrate;

[0108] like Figure 3A As shown in step (2), the first pre-treated sample 204 is placed at a position of the circular opening of the silicon substrate 301 away from the preset area 2041 at one end of the in-situ nano-manipulator;

[0109] Here, the preset area can be determined according to the size of the first pretreated sample and the silicon substrate, and this embodiment of the present application does not limit this.

[0110] Step 308: Welding the silicon substrate to the predetermined area of ​​the first pre-treated sample;

[0111] Welding Figure 3A The silicon substrate 301 shown in step (2) and the preset area 2041 of the first pre-treated sample 204 are obtained as shown in FIG. Figure 3A The structure shown in step (3) in .

[0112] Here, the welding of the silicon substrate and the preset area of ​​the first pretreated sample can be achieved by depositing welding metal, wherein the welding metal can also be tungsten or platinum, and the deposition area of ​​the welding metal can be slightly larger than the diameter of the circular mouth of the silicon substrate. The deposition can be performed 1 to 2 times to ensure that the thickness of the deposited layer of the welding metal can fill the gap between the silicon substrate and the preset area of ​​the first pretreated sample, thereby achieving the welding of the silicon substrate and the preset area of ​​the first pretreated sample.

[0113] Step 309: cutting off the preset area from the first pre-processed sample to obtain a first intermediate measurement sample and a second pre-processed sample;

[0114] Using a focused ion beam Figure 3A The preset area 2041 shown in step (2) is cut off from the first pre-treated sample 204, and the result is as follows Figure 3A The first intermediate measurement sample 303 and the second pre-processed sample 304 shown in step (3);

[0115] Step 310: performing circular cutting on the first intermediate measurement sample to obtain a conical first final measurement sample.

[0116] like Figure 3A As shown in step (4) of the process, the first intermediate measurement sample 303 is subjected to annular cutting to obtain the conical first final measurement sample 305 shown in step (5).

[0117] Figure 3BThis is an enlarged view of the first final measurement sample 305. It can be seen that the first final measurement sample 305 contains a capacitor column 10, and the capacitor column 10 is surrounded by a circle of first protective material 105, so that when using FIB for ring cutting, the complex structure of the capacitor column will not cause difficulties in sample preparation.

[0118] During implementation, the focused ion beam can be configured in a ring shape. Specifically, an etching ring is placed at the center of the first intermediate measurement sample. During etching, a high current can be used first, followed by a low current. The first intermediate measurement sample is etched in a ring shape from top to bottom, and the etching progress is monitored at all times. If the etching amount is too large or too small, adjustments can be made at any time. In some embodiments, the ring cutting current can be 20 to 40 picoamperes (pA) to improve the accuracy of the ring cutting process and obtain a conical sample with a tip diameter of less than 100 nm.

[0119] In some embodiments, since the first final measurement sample is used for testing a three-dimensional atom probe, and the test sample of the three-dimensional atom probe is required to have a diameter less than 100 nm, the first final measurement sample can be a conical sample with a tip diameter less than 100 nm.

[0120] In some embodiments, the implementation of step 308 of “welding the silicon substrate to the predetermined area of ​​the first pre-treated sample” includes:

[0121] Step 3081: turning the silicon substrate and the first pre-treated sample 180°;

[0122] like Figure 3C As shown in step (3) in Figure 3A After step (2), the silicon substrate 301 and the first pre-treated sample 204 are turned 180 degrees. In this way, it is easy to deposit welding metal between the silicon substrate and the first pre-treated sample, making the operation more convenient.

[0123] Step 3082: depositing welding metal on the circular opening of the silicon substrate to weld the silicon substrate to the preset area of ​​the first pre-treated sample;

[0124] like Figure 3C As shown in step (3), welding metal is deposited on the circular opening of the silicon substrate 301 to weld the silicon substrate 301 to the preset area 2041 of the first pre-processed sample 204.

[0125] Correspondingly, the implementation of step 309 of “cutting the predetermined area from the first pre-processed sample to obtain a first intermediate measurement sample and a second pre-processed sample” includes:

[0126] Step 3091: turning the welded silicon substrate and the first pre-treated sample 180°;

[0127] like Figure 3C As shown in step (3) of FIG, the welded silicon substrate 301 and the first pre-treated sample 204 are turned 180° to obtain Figure 3C The structure shown in step (4) in .

[0128] Step 3092: Cut off the preset area of ​​the first preprocessed sample from the first preprocessed sample to obtain the first intermediate measurement sample and the second preprocessed sample.

[0129] will be as Figure 3C The predetermined area 2041 of the first pre-treated sample 204 shown in step (2) is cut off from the first pre-treated sample 204 to obtain the following Figure 3C The first intermediate measurement sample 303 and the second pre-processed sample 304 shown in step (4) in FIG.

[0130] In some embodiments, after step 310 of “performing circular cutting on the first intermediate measurement sample to obtain a conical first final measurement sample”, the method further includes:

[0131] Step 311: obtaining a second intermediate measurement sample based on the second pre-processed sample;

[0132] Here, the implementation steps of the first intermediate measurement sample can be used to obtain the second intermediate measurement sample, namely:

[0133] Step 3111: Providing a silicon substrate;

[0134] Step 3112: placing the second pre-treated sample at a predetermined area away from one end of the in-situ nano-manipulator at a position of the circular opening of the silicon substrate;

[0135] Step 3113: Welding the silicon substrate and the predetermined area of ​​the second pre-treated sample;

[0136] Step 309: cutting the preset area from the second pre-processed sample to obtain a second intermediate measurement sample and a third pre-processed sample;

[0137] Step 312: performing circular cutting on the second intermediate measurement sample to obtain a conical second final measurement sample.

[0138] Here, step 312 may refer to step 310 .

[0139] In some embodiments, one first pre-treated sample can be used to prepare three final measurement samples. Of course, the number of final measurement samples that can be prepared from one first pre-treated sample can also be determined based on the lengths of the first pre-treated sample and the final measurement sample.

[0140] In some embodiments, when the sample to be tested is a semiconductor device including capacitor columns, samples can be prepared for all capacitor columns to be tested and tested to obtain the concentration and distribution of doping elements in the capacitor column dielectric layer in the entire semiconductor device.

[0141] The present invention provides a sample preparation method, which comprises:

[0142] Step 401: Figure 1D As shown, a sample to be tested is provided, wherein the sample to be tested is a semiconductor device including a capacitor column 10; each capacitor column 10 includes a lower electrode layer 102, an upper electrode layer 101 and a dielectric layer 103 located between the lower electrode layer 102 and the upper electrode layer 101, and the dielectric layer 103 includes a doping element;

[0143] Step 402: Acquire an image of the sample to be detected;

[0144] Step 403: determining a region to be detected in the sample to be detected in the image;

[0145] Here, steps 402 to 403 refer to steps S1041 and S1042. Figure 1D The middle capacitor column 10 is the area to be detected.

[0146] Step 404: Figure 1E As shown, based on the area to be detected, a pre-processing area 104 located around the area to be detected is determined, wherein the pre-processing area 104 is annular, the diameter d1 of the inner ring is equal to the first preset diameter, and the diameter d2 of the outer ring of the pre-processing area is 300 to 500 nm;

[0147] Step 405: Etching the pre-treated area to a first preset depth, wherein the first preset depth is 200 to 1000 nm;

[0148] Here, step 405 refers to step S106.

[0149] Step 406: Figure 1F As shown, a first protective material 105 is filled in the pre-processed area and is not lower than the upper surface of the area to be inspected, wherein the first protective material is silicon dioxide;

[0150] Step 407: Figure 2H As shown in steps (1) and (2) in the embodiment, a protective layer and a conductive layer 203 are sequentially deposited on the upper surface of the protection zone 201; wherein the thickness of the protective layer is 100 to 200 nm, the thickness of the conductive layer is 300 to 1000 nm, and the protection zone is at least composed of the following: Figure 1E The area of ​​the partial pre-processing area 104 and the area to be detected (i.e., the area of ​​the capacitor column 10) shown in FIG.

[0151] Step 408: Figure 2H As shown in step (3), the peripheral area of ​​the protection zone 201 is etched to a second predetermined depth;

[0152] Step 409: Figure 2D As shown, the connection between the protection zone 201 and the sample to be detected 30 is cut off at the second preset depth d4, and the first side D is kept connected to the sample to be detected 30 to obtain a cantilever structure;

[0153] Step 410: Figure 2H As shown in step (4) in the embodiment, the tip of the in-situ nanomanipulator 202 is moved to above the second side E in the protection zone 201;

[0154] Step 411: Figure 2H As shown in step (5), a welding metal is deposited on the tip of the in-situ nanomanipulator 202 to fill the gap between the in-situ nanomanipulator 202 and the second side E, so that the in-situ nanomanipulator 202 is welded to the second side E in the protection zone 201 opposite to the first side D, wherein the welding metal includes tungsten or platinum;

[0155] Step 412: Figure 2H As shown in step (6) of Figure 2H The first side D shown in step (5) is connected to the sample 30 to be tested, and the result is as follows Figure 2H The first pre-treated sample 204 shown in step (6);

[0156] Step 413: Figure 3A As shown in step (1), a silicon substrate 301 is provided;

[0157] Step 414: Figure 3A As shown in step (2), the first pre-treated sample 204 is placed at a position of the circular opening of the silicon substrate 301 away from the preset area 2041 at one end of the in-situ nano-manipulator;

[0158] Step 415: Figure 3C As shown in step (3), the silicon substrate 301 and the first pre-treated sample 204 are flipped 180°;

[0159] Step 416: Figure 3C As shown in step (3), welding metal is deposited on the circular opening of the silicon substrate 301 to weld the silicon substrate 301 to the preset area 2041 of the first pre-processed sample 204;

[0160] Step 417: Figure 3C The welded silicon substrate 301 and the first pre-treated sample 204 shown in step (3) are turned 180° to obtain the following Figure 3CThe structure shown in step (4) in ;

[0161] Step 418: Figure 3C The predetermined area 2041 of the first pre-treated sample 204 shown in step (2) is cut off from the first pre-treated sample 204 to obtain the following Figure 3C The first intermediate measurement sample 303 and the second pre-processed sample 304 shown in step (4);

[0162] Step 419: Figure 3A As shown in step (4), the first intermediate measurement sample 303 is subjected to ring cutting to obtain the conical first final measurement sample 305 shown in step (5), wherein the first final measurement sample is a conical sample with a tip diameter of less than 100 nm and the ring cutting current is 20 to 40 pA.

[0163] Step 420: Obtain a second intermediate measurement sample based on the second pre-processed sample;

[0164] Step 421: performing circular cutting on the second intermediate measurement sample to obtain a conical second final measurement sample.

[0165] Here, steps 420 to 421 correspond to steps 311 to 312 respectively.

[0166] The features disclosed in the several method or structural embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments or structural embodiments.

[0167] The description of the semiconductor structure embodiment above is similar to the description of the method embodiment above, and has similar beneficial effects as the method embodiment. For technical details not disclosed in the semiconductor structure embodiment of this application, please refer to the description of the method embodiment of this application for understanding.

[0168] The above description is merely an exemplary embodiment of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A sample preparation method, characterized in that: include: Providing a sample to be tested, wherein the sample to be tested is a semiconductor device including a capacitor column; Determine a to-be-detected area in the to-be-detected sample and a pre-processed area located around the to-be-detected area, wherein the pre-processed area is annular, the inner diameter of which is a first preset diameter, and the area where the capacitance column is located is the to-be-detected area; Etching the pre-treated area to a first preset depth; Filling the pre-processing area with a first protective material not lower than the upper surface of the area to be inspected; The pretreatment area and the area to be detected are pretreated to obtain a first pretreated sample.

2. The method according to claim 1, characterized in that The determining of the to-be-detected area in the to-be-detected sample and the pre-processed area located around the to-be-detected area comprises: Acquiring an image of the sample to be detected; determining a region to be detected in the sample to be detected in the image; Based on the area to be detected, a pre-processing area located around the area to be detected is determined.

3. The method according to claim 2, characterized in that The capacitor column at least includes an upper electrode layer, a lower electrode layer, and a dielectric layer located between the upper electrode layer and the lower electrode layer, and the dielectric layer includes a doping element.

4. The method according to claim 3, characterized in that The value range of the first preset diameter is 1 to 1.5 times the diameter of the capacitor column.

5. The method according to claim 4, characterized in that The diameter of the outer ring of the pretreatment area is larger than a second preset diameter, and the second preset diameter is 100 to 300 nm.

6. The method according to claim 4, characterized in that The first preset depth is 200 to 1000 nm.

7. The method according to claim 1, characterized in that The first protective material is silicon dioxide.

8. The method according to any one of claims 1 to 7, characterized in that The pre-processing the pre-processed area and the area to be detected to obtain a first pre-processed sample comprises: Etching a peripheral area of ​​the protection zone to a second preset depth, wherein the protection zone is an area including at least a portion of the pre-processing zone and the area to be detected; Cutting off the connection between the protection zone and the sample to be detected at the second preset depth, leaving the first side connected to the sample to be detected, to obtain a cantilever structure; welding an in-situ nano-manipulator to a second side of the protection zone opposite to the first side; The first side and the sample to be detected are cut off to obtain the first pretreated sample.

9. The method according to claim 8, characterized in that The step of welding the in-situ nano-manipulator to a second side of the protection zone opposite to the first side comprises: moving the tip of the in-situ nanomanipulator over the second side in the protection zone; A welding metal is deposited onto the tip of the in-situ nano-manipulator to fill a gap between the in-situ nano-manipulator and the second side, so that the in-situ nano-manipulator is welded to the second side of the protection zone opposite to the first side.

10. The method according to claim 9, characterized in that The weld metal includes tungsten or platinum.

11. The method according to claim 8, characterized in that Before etching the peripheral area of ​​the protection zone to the second preset depth, the method further includes: A protective layer and a conductive layer are sequentially deposited on the upper surface of the protection zone; wherein the thickness of the protective layer is 100 to 200 nm, and the thickness of the conductive layer is 300 to 1000 nm.

12. The method according to claim 8, characterized in that After obtaining the first pretreated sample, the method further includes: providing a silicon substrate; placing the first pre-treated sample at a predetermined area away from one end of the in-situ nanomanipulator at a position of the circular opening of the silicon substrate; welding the silicon substrate to a predetermined area of ​​the first pretreated sample; cutting the predetermined area from the first pre-processed sample to obtain a first intermediate measurement sample and a second pre-processed sample; The first intermediate measurement sample is circularly cut to obtain a conical first final measurement sample.

13. The method according to claim 12, characterized in that The step of welding the silicon substrate and the preset area of ​​the first pre-treated sample comprises: Turning the silicon substrate and the first pretreated sample 180°; Depositing welding metal on the circular opening of the silicon substrate to weld the silicon substrate to the preset area of ​​the first pretreated sample; Correspondingly, cutting off the preset area from the first preprocessed sample to obtain a first intermediate measurement sample and a second preprocessed sample includes: Turning the welded silicon substrate and the first pretreated sample 180°; The preset area of ​​the first pretreated sample is cut off from the first pretreated sample to obtain the first intermediate measurement sample and the second pretreated sample.

14. The method according to claim 12, characterized in that The first final measurement sample is a conical sample with a tip diameter less than 100 nm.

15. The method according to claim 12, characterized in that The ring cutting current is 20 to 40 pA.

16. The method according to claim 12, characterized in that After obtaining the first final measurement sample in a conical shape, the method further comprises: obtaining a second intermediate measurement sample based on the second pretreated sample; The second intermediate measurement sample is circularly cut to obtain a conical second final measurement sample.

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