Method for processing a transmission sample with a focused ion beam

Abstract

This application discloses a method for processing a transmission sample using a focused ion beam, comprising the following steps: using a focused ion beam to thin the transmission sample as a whole to form a thinned region, the thickness of the thinned region being a first preset thickness, and a supporting beam being formed around the periphery of the thinned region, the thickness of the supporting beam being greater than the first preset thickness; using a focused ion beam to perform partitioned thinning of the thinned region of the transmission sample to form at least two unit thin regions within the thinned region, the thickness of each unit thin region being less than a second preset thickness, the lateral width of each unit thin region being a first preset distance, and the interval between two adjacent unit thin regions being a second preset distance.

Description

Technical Field

[0001] This application relates to the field of sample preparation technology, and in particular to a method for processing transmission samples using a focused ion beam. Background Technology

[0002] The semiconductor industry has been driven by a relentless pursuit of miniaturization, a trend that follows Moore's Law, which assumes the number of transistors on a microchip roughly doubles every two years, leading to continuous performance improvements and decreasing costs per transistor. This trend has led the semiconductor industry to focus on shrinking device manufacturing processes—that is, reducing the size of semiconductor devices on a chip. The shift from deep ultraviolet to extreme ultraviolet lithography (a process that etches circuit patterns onto a silicon wafer) has made it possible to define features much smaller than before, allowing semiconductor devices to continue shrinking in size. In 2017, semiconductor manufacturing processes entered the 10nm node, in 2018 the 7nm node, and in 2020 the 5nm process node.

[0003] Transmission electron microscopy (TEM) plays a crucial role in advancing chip manufacturing processes and quality control, especially as the semiconductor industry moves towards sub-10nm scales. At these ultra-fine dimensions, the structural integrity, material composition, and electrical properties of semiconductor devices become increasingly sensitive to atomic-level defects. TEM's superior spatial resolution and analytical capabilities are indispensable for ensuring the performance and reliability of nanoscale devices. Therefore, for electronic devices with fabrication processes below 10nm, it is necessary to achieve TEM sample preparation with thicknesses less than 10 nm.

[0004] On the other hand, fabricating lens samples for TEM to a thickness of less than 10 nm is crucial for high-resolution atomic structure imaging. This not only improves image quality and contrast but also reduces multiple scattering events and potential sample damage, ultimately leading to more precise and accurate atomic structure characterization. Particularly for atomic-resolution scanning transmission electron microscopy (STEM) and differential phase contrast (DPC) characterization, fabricating sample thicknesses to below 10 nm significantly improves the clarity and accuracy of atomic structure images. This is especially important in materials science and semiconductor device development, as understanding atomic-scale structures is key to developing and controlling material properties.

[0005] Existing lens sample preparation methods involve using focused ion beam microscopy (FIB) in conjunction with low-energy ion grinding or other techniques to thin the sample to the desired thickness. These include schemes (1) and (2). Scheme (1) uses conventional FIB sample preparation methods to process the lens sample to a thickness of 30 nm, and then uses Ar ion beam grinding to further reduce the sample thickness to below 10 nm.

[0006] Scheme (2) involves using lift-out technology to cut a small sample slice from the original sample, then using a robotic arm to rotate the sample slice by 180 degrees before welding it onto a TEM stage. Lens samples with a thickness of less than 10 nm can be obtained using the inverted thinning method.

[0007] In the process of realizing this invention, the inventors discovered that the above-mentioned scheme (1) requires the use of two devices, FIB and ion milling, to prepare lens samples, which increases the complexity of the sample preparation process. Conventional FIB-prepared lens samples can process thin areas with a width of 5-10 μm, but when the sample thickness is reduced to 10 nm, thin areas above the 5 μm scale will bend. Therefore, the thin area width needs to be reduced to the range of 2-3 μm, which leads to a reduction in the observable area. Current ion milling equipment has a positioning function at the 10-20 μm scale, thus requiring large-scale milling, making it difficult to achieve precise positioning and thinning of 2 μm thin areas and precise thickness control. If ion milling with a thickness below 10 nm is required, multiple parameter tests and thickness measurements are necessary, thus requiring additional time and technical experience to achieve the target thickness sample preparation.

[0008] The above-mentioned scheme (2), which involves rotating the thin slice by 180 degrees after extracting the thin sample region, places high demands on the functionality and rotational alignment of the robotic arm. Furthermore, the precise positioning of the inverted thinning process requires extensive FIB operation experience and a high level of technical skill. Therefore, using this scheme to prepare 10nm thick TEM samples places high demands on both the FIB equipment and the FIB operators. Summary of the Invention

[0009] This application provides a method for processing transmission samples using focused ion beams. Under the framework of conventional sample preparation techniques, it can achieve sample preparation with a thickness of less than 10 nm by designing a thinner structure. It also simplifies the operation process of existing methods, making the preparation of transmission samples with a thickness of less than 10 nm simple and efficient, and reducing the technical difficulty of sample preparation.

[0010] This application provides a method for processing transmission samples using a focused ion beam, comprising the following steps:

[0011] The above-mentioned transmission sample is thinned as a whole using a focused ion beam to form an overall thinned region. The thickness of the overall thinned region is a first preset thickness, and a supporting beam is formed around the overall thinned region. The thickness of the supporting beam is greater than the first preset thickness.

[0012] The overall thinning region of the above-mentioned transmission sample is thinned in sections using a focused ion beam to form at least two unit thin regions within the overall thinning region. The thickness of each unit thin region is less than a second preset thickness, the lateral width of each unit thin region is a first preset distance, and the interval between two adjacent unit thin regions is a second preset distance.

[0013] In some embodiments, the above-mentioned use of a focused ion beam to thin the entire transmission sample to form an overall thinned region includes:

[0014] The transmission sample is processed for the first time using a step-cutting mode with a first ion beam voltage and current, a first cutting angle and a first cutting depth to form a first overall thinning region, which has a third preset thickness.

[0015] Using a step-cutting mode, the above-mentioned transmission sample is further processed a second time with a second ion beam voltage and current, a first cutting angle and a second cutting depth to form the above-mentioned overall thinning region, which has a third preset thickness.

[0016] The transmission sample is processed a third time using a third ion beam voltage and current, a first cutting angle, and a third cutting depth, so that the thickness of the overall thinned region reaches the first preset thickness.

[0017] In some embodiments, the third cutting depth is equal to the first cutting depth and the second cutting depth, and is less than the longitudinal width of the transmission sample.

[0018] In some embodiments, the first switching cutting angle is 1.2 degrees, the third preset thickness is 500 nm, the first preset thickness is 300 nm, and the first cutting depth, the second cutting depth, and the third cutting depth are 4.5 μm, 1.5 μm, and 6 μm, respectively.

[0019] In some embodiments, the first ion beam voltage and current are 30KV and 0.23nA, the second ion beam voltage and current are 30KV and 80pA, and the third ion beam voltage and current are 30KV and 40pA.

[0020] In some embodiments, the above-mentioned use of a focused ion beam to perform partitioned thinning of the overall thinning region of the transmission sample, to form at least two unit thin regions within the overall thinning region, includes:

[0021] Using a fourth ion beam voltage and current, a first cutting angle, and a fourth cutting depth, at least two unit thin regions in the above-mentioned overall thinning region are processed for the first time to obtain at least two unit thin regions with a fourth preset thickness.

[0022] Using the fifth ion beam voltage and current, the first cutting angle, and the fourth cutting depth, at least two unit thin regions in the above-mentioned overall thinning region are processed a second time to obtain at least two unit thin regions with a fifth preset thickness.

[0023] Using a sixth ion beam voltage and current, a second cutting angle, and a fourth cutting depth, at least two unit thin regions in the overall thinning region are processed a third time to obtain at least two unit thin regions with a sixth preset thickness.

[0024] Using the seventh ion beam voltage and current, the second cutting angle, and the fourth cutting depth, at least two unit thin regions in the overall thinning region are processed for the fourth time to obtain at least two unit thin regions with a thickness less than the second preset thickness.

[0025] In some embodiments, the fourth cutting depth is less than or equal to the third cutting depth.

[0026] In some embodiments, the second cutting angle is 3 degrees, and the second preset depth, the fourth preset depth, the fifth preset depth and the sixth preset depth are 10nm, 150nm, 100nm and 30nm respectively.

[0027] In some embodiments, the fourth ion beam voltage and current are 16KV and 23pA, the fifth ion beam voltage and current are 8KV and 21pA, the sixth ion beam voltage and current are 5KV and 7pA, and the seventh ion beam voltage and current are 2KV and 9pA.

[0028] In some embodiments, before the overall thinning of the transmission sample using a focused ion beam, the method further includes: forming a protective layer on the original surface of the lens sample, wherein the thickness of the protective layer is greater than 2.5 μm.

[0029] This application utilizes a focused ion beam to thin the transmission sample as a whole, forming a thinned region. The thickness of this thinned region is a first preset thickness, and a supporting beam is formed around its perimeter, with the supporting beam having a thickness greater than the first preset thickness. The thinned region is then further divided into sections using the focused ion beam to form at least two unit thin regions within the overall thinned area. Each unit thin region has a thickness less than a second preset thickness, a lateral width of a first preset distance, and a spacing of a second preset distance between adjacent unit thin regions. This invention employs a preparation process of first thinning the entire transmission sample and then thinning it in sections, simplifying the preparation of 10nm thick transmission electron microscope samples, reducing the technical requirements for thinning, and preventing bending deformation after the thin film thickness within the frame is reduced by the supporting beam, thus ensuring the stability and accuracy of the sample.

[0030] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0031] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0032] Figure 1 This is a planar schematic diagram of the transmission sample thinning structure provided in the embodiments of this application;

[0033] Figure 2 This is a cross-sectional schematic diagram of the thinned structure of the transmission sample provided in the embodiments of this application;

[0034] Figure 3 A flowchart illustrating a method for processing transmission samples using a focused ion beam, as provided in this application embodiment;

[0035] Figure 4 This application provides a schematic diagram of a specific process for overall thinning of a transmission sample using a focused ion beam, as shown in the embodiments of this application.

[0036] Figure 5 This application provides a schematic diagram of a specific process for using a focused ion beam to perform partitioned thinning of a transmission sample, as illustrated in an embodiment of the present application.

[0037] Figure 6 A scanning electron microscope illustration of a process for processing a transmission sample using a focused ion beam microscope, provided as an embodiment of this application;

[0038] Figure 7 This is an image showing the effect of a STEM probe used in an embodiment of this application to observe a thin region of a transmitted sample with a thickness of less than 10 nm.

[0039] Figure 8 Atomic resolution transmission pattern of a transmission sample with a device stack structure of W / HfZrOx / W provided in the embodiments of this application. Detailed Implementation

[0040] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0041] This application combines the conventional sample preparation extraction process with the reverse-cutting thinning process, performing partitioned thinning and reverse-cutting thinning in a plane to achieve a reverse-cutting thinning region thickness of less than 10 nm in each partition. The design diagram of the thinning structure is shown below. Figure 1 As shown, at least two partitions, or unit thin areas, can be fabricated on sample slices wider than 10 μm. The width of each partition and the spacing between partitions can be designed according to actual needs, for example... Figure 1 As shown, three partitions can be set, each with a width of 2µm and a spacing of 1µm. Then, each partition unit is thinned using inverted thinning parameters to obtain the desired result. Figure 2 The transmission electron microscope observation area shown is less than 10 nm thick.

[0042] Figure 3 This is a flowchart illustrating a method for processing transmission samples using a focused ion beam, as provided in an embodiment of this application. Figure 4 This is a schematic diagram illustrating a specific process for overall thinning of a transmission sample using a focused ion beam, as provided in an embodiment of this application. Figure 5 This is a schematic diagram illustrating a specific process for partitioned thinning of a transmission sample using a focused ion beam, as provided in an embodiment of this application.

[0043] like Figure 3 As shown, the process of processing a transmission sample using a focused ion beam includes the following steps:

[0044] Step S101: The transmitted sample is thinned as a whole using a focused ion beam to form an overall thinning region 102. The thickness of the overall thinning region 102 is a first preset thickness, and a supporting beam 101 is formed around the overall thinning region 102. The thickness of the supporting beam 101 is greater than the first preset thickness.

[0045] Prepare the transmission sample to be thinned, ensuring its surface is clean and free of contaminants. Fix the sample on the sample stage, ensuring its stability and precise position control. Using the ion beam source in a focused ion beam microscope, irradiate a specific area of ​​the sample surface with a focused ion beam. Adjust the ion beam current and voltage to control the intensity and direction of the ion beam, ensuring precise cutting and thinning of the sample. Based on a preset first thickness, gradually adjust the ion beam parameters to thin the sample overall. During the thinning process, continuously monitor the morphology and thickness changes of the sample to ensure the controllability and accuracy of the thinning process. Around the overall thinning area 102, form a support beam 101 with a thickness greater than the first preset thickness by adjusting the irradiation range and intensity of the ion beam. The presence of the support beam 101 maintains the stability of the overall thinning area 102, preventing deformation or damage during subsequent processing or use.

[0046] Step S102: Use a focused ion beam to perform partitioned thinning of the overall thinning region 102 of the transmission sample, so as to form at least two unit thin regions 103 within the overall thinning region 102. The thickness of each unit thin region 103 is less than a second preset thickness, the lateral width of each unit thin region 103 is a first preset distance, and the interval between two adjacent unit thin regions 103 is a second preset distance.

[0047] For example, in a focused ion beam microscope, parameters such as the accelerating voltage, beam current, and scanning speed of the ion beam are set to ensure precise material removal. The focused ion beam is used to form at least two unit thin regions 103 within the overall thinning region 102. The thickness of each unit thin region 103 is less than a second preset thickness, the lateral width of each unit thin region 103 is a first preset distance, and the interval between two adjacent unit thin regions 103 is a second preset distance. Figure 1 As shown. During the processing, it is necessary to closely monitor the changes in the surface morphology and thickness of the sample, and adjust the processing parameters in a timely manner to maintain the required accuracy and uniformity.

[0048] This application utilizes a focused ion beam to thin the transmission sample as a whole, forming a thinned region. The thickness of this thinned region is a first preset thickness, and a supporting beam is formed around its perimeter, with the supporting beam having a thickness greater than the first preset thickness. The thinned region is then further divided into sections using the focused ion beam to form at least two unit thin regions within the overall thinned area. Each unit thin region has a thickness less than a second preset thickness, a lateral width of a first preset distance, and a spacing of a second preset distance between adjacent unit thin regions. This invention employs a preparation process of first thinning the entire transmission sample and then thinning it in sections, simplifying the preparation of 10nm thick transmission electron microscope samples, reducing the technical requirements for thinning, and preventing bending deformation after the thin film thickness within the frame is reduced by the supporting beam, thus ensuring the stability and accuracy of the sample.

[0049] The specific steps are as follows:

[0050] like Figure 4 As shown, in step S101 of the above embodiment, the overall thinning of the transmission sample using a focused ion beam to form an overall thinned region 102 may include the following steps:

[0051] Step S201: Using a step-cutting mode, the transmission sample is processed for the first time with the first ion beam voltage and current, the first cutting angle and the first cutting depth to form a first overall thinning region 1021, which has a third preset thickness.

[0052] For example, such as Figure 1 As shown, a step-cutting mode in focused ion beam is adopted. The first ion beam voltage and current are set to 30KV and 0.23nA, the first cutting angle (i.e., the tilt angle of the transmitted sample relative to the incident direction of the ion beam) is 1.2 degrees, and the first cutting depth is 4.5µm. This depth setting allows for the retention of a 1-2µm wide bottom support beam, preventing bending deformation after the film thickness within the frame decreases. Under the first ion beam current of 0.23nA, the thickness of the transmitted sample is reduced to a third preset thickness of 500nm, forming a first overall thinning region 1021.

[0053] Step S202: Using a step-cutting mode, the transmission sample is further processed a second time with the second ion beam voltage and current, the first cutting angle and the second cutting depth to form an overall thinning region 102, which has a third preset thickness.

[0054] For example, a step-cutting mode in focused ion beam technology is adopted, with the voltage of the second ion beam set to 30 kV and the current to 80 pA. The first cutting angle, i.e., the tilt angle of the transmitted sample relative to the incident direction of the ion beam, is set to 1.2 degrees. Simultaneously, the second cutting depth is set to 1.5 μm. This cutting depth setting ensures that the thinned surface of the transmitted sample has a uniform thickness, avoiding the formation of a wedge-shaped thickness gradient at the bottom. While maintaining the second ion beam current at 80 pA, cutting continues until the sample thickness is reduced to a third preset thickness, i.e., 500 nm.

[0055] Step S203: The transmission sample is processed for the third time using the third ion beam voltage and current, the first cutting angle and the third cutting depth, so that the thickness of the overall thinning region 102 reaches the first preset thickness.

[0056] For example, a step-cutting mode in focused ion beam (FIB) is adopted, and the parameters of the FIB are set as follows: the voltage of the third ion beam is 30 kV, and the current is 40 pA. Simultaneously, the tilt angle of the thin film relative to the incident direction of the ion beam, i.e., the first cutting angle, is set to 1.2 degrees. The cutting depth is set to a third cutting depth of 6 μm, where the third cutting depth is equal to the sum of the first and second cutting depths, and is less than the longitudinal width of the transmitted sample (10 μm). The thickness of the thin region of the sample is reduced to a first preset thickness, i.e., 300 nm.

[0057] Then, the overall thinning region 102 of the transmission sample is thinned in sections using a focused ion beam to form at least two unit thin regions 103 within the overall thinning region 102.

[0058] like Figure 5 As shown, step S102 above, which involves using a focused ion beam to perform sectional thinning of the transmission sample, may include the following steps:

[0059] Step S301: Using the fourth ion beam voltage and current, the first cutting angle and the fourth cutting depth, at least two unit thin regions 103 in the overall thinning region 102 are processed for the first time to obtain at least two unit thin regions 103 with a fourth preset thickness.

[0060] For example, a full-surface chipping mode is adopted, and a focused ion beam is used to divide the sample thin region into sections. The lateral width of each unit thin region 103 is a first preset distance of 2 μm, and the spacing between two adjacent unit thin regions 103 is a second preset distance of 1 μm. The parameters of the focused ion beam are set as follows: the voltage of the fourth ion beam is 16 kV, and the current is 23 pA. At the same time, the tilt angle of the thin film relative to the incident direction of the ion beam, i.e., the first cutting angle, is set to 1.2 degrees. The cutting depth is a fourth cutting depth, wherein the fourth cutting depth is less than or equal to the third cutting depth of 6 μm. The thickness of the unit thin region 103 of the sample is reduced to a fourth preset thickness, i.e., 150 nm.

[0061] Step S302: Using the fifth ion beam voltage and current, the first cutting angle and the fourth cutting depth, at least two unit thin regions 103 in the overall thinning region 102 are processed a second time to obtain at least two unit thin regions 103 with a fifth preset thickness.

[0062] For example, using a full-surface chipping mode, at least two unit thin regions 103 in the overall thinning region 102 are processed a second time. The parameters of the focused ion beam are set as follows: the voltage of the fifth ion beam is 8KV, and the current is 21pA. Simultaneously, the tilt angle of the sheet relative to the ion beam incident direction, i.e., the first cutting angle, is set to 1.2 degrees. The cutting depth is a fourth cutting depth, wherein the fourth cutting depth is less than or equal to the third cutting depth of 6µm. The thickness of the unit thin region 103 of the sample is reduced to a fifth preset thickness, i.e., 100nm.

[0063] Step S303: Using the sixth ion beam voltage and current, the second cutting angle and the fourth cutting depth, at least two unit thin regions 103 in the overall thinning region 102 are processed for the third time to obtain at least two unit thin regions 103 with a sixth preset thickness.

[0064] For example, using a full-surface chipping mode, at least two unit thin areas 103 in the overall thinning region 102 are processed a third time, and the parameters of the focused ion beam are set: the voltage of the sixth ion beam is 5KV, and the current is 7pA. Simultaneously, the tilt angle of the sheet relative to the ion beam incident direction, i.e., the second cutting angle, is set to 3 degrees. The cutting depth is set to a fourth cutting depth, where the fourth cutting depth is less than or equal to the third cutting depth of 6µm. The cutting position is precisely set to a rectangle 2µm long and 1µm wide, thereby forming a reverse-cut structure, such as... Figure 2 As shown. The thinning location is selected as the target observation area or the stacked region. The cutting time is set to 20s. The operation sequence is to first thin the front side, and then process the back side, until the unit thin region 103 of the sample is processed to the preset sixth thickness, i.e., 30nm.

[0065] Step S304: Using the seventh ion beam voltage and current, the second cutting angle and the fourth cutting depth, at least two unit thin regions 103 in the overall thinning region 102 are processed for the fourth time to obtain at least two unit thin regions 103 with a thickness less than the second preset thickness.

[0066] For example, using a full-surface chipping mode, at least two unit thin regions 103 in the overall thinning region 102 are processed for the fourth time. The parameters of the focused ion beam are set as follows: the voltage of the seventh ion beam is 2KV, and the current is 9pA. Simultaneously, the tilt angle of the sheet relative to the ion beam incident direction, i.e., the second cutting angle, is set to 3 degrees. The cutting depth is the fourth cutting depth, where the fourth cutting depth is less than or equal to the third cutting depth of 6µm. The thickness of the unit thin region 103 of the sample is reduced to a second preset thickness, i.e., 10nm. During the low-voltage thinning steps S303 and S304, holes may appear in the unit thin region 103, such as… Figure 6 As shown, the thickness of the sample around such a hole under transmission electron microscopy is generally less than 10 nm. During low-voltage thinning, it is necessary to carefully control the thinning position and rate to ensure that the hole is close to the target thin region but does not damage the thin region.

[0067] In this embodiment of the application, before using a focused ion beam to thin the lens sample as a whole, a protective layer needs to be formed on the original surface of the transmission sample, and the thickness of the protective layer is greater than 2.5 μm.

[0068] The scanning electron microscope results of thinning using the above focused ion beam sample preparation parameters are as follows: Figure 6 As shown. On a focused ion beam microscope equipped with a scanning transmission electron microscope (STEM) probe, preliminary observation of the thin region can be performed. In this example, the device stack structure used is W / HfZrOx / W. After partitioned inverted thinning, the W metal layer exhibits significant polycrystalline particle contrast in the DF2 observation mode of the STEM probe, indicating that the sample thickness has reached 10 nm, which can be used for subsequent STEM characterization, such as... Figure 7 As shown.

[0069] The multilayer structure samples with a thickness of less than 10 nm obtained using the above thinning method can provide very clear transmission maps with atomic resolution, such as... Figure 8 As shown, DPC technology can be used to observe such samples, revealing the distribution of oxygen atoms and the corresponding electric field distribution. This information provides crucial data support for exploring the physical mechanisms of materials.

[0070] The sample preparation method designed in this invention has the following two advantages:

[0071] First, the sample preparation method designed in this invention can achieve sample preparation with a thickness of less than 10 nm within the framework of conventional sample preparation techniques through the design of a thinning structure. This invention is an innovative sample preparation scheme that combines a conventional sample preparation method with a reverse-cutting thinning method. By redesigning the structure used for thinning, this method can achieve higher precision and control, thus enabling thicknesses below 10 nm. The method of this invention improves the clarity and accuracy of acquired transmission electron microscopy (TEM) data. The results of TEM characterization show that samples prepared using this invention can effectively improve the quality of academic research and analysis.

[0072] Secondly, the method designed in this invention simplifies the operation process of existing solutions, making the preparation of transmission samples with a thickness of less than 10 nm simple and efficient, and reducing the technical difficulty of sample preparation. A comparison with the two existing solutions reveals that the solution designed in this invention does not require the Ar ion grinding process after FIB processing, nor does it require the 180-degree rotation operation after sample extraction, greatly simplifying the sample preparation process, saving preparation time, and improving sample preparation efficiency.

[0073] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0074] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified. Any process or method description in the flowcharts or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more N executable instructions for implementing customized logical functions or processes, and the scope of preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order according to the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

Claims

1. A method for processing transmission samples using a focused ion beam, characterized in that, Includes the following steps: The transmitted sample is thinned overall using a focused ion beam to form a thinned region. The thickness of the thinned region is a first preset thickness, and a supporting beam is formed around the periphery of the thinned region. The thickness of the supporting beam is greater than the first preset thickness. The process of thinning the transmitted sample overall using a focused ion beam to form the thinned region includes: The transmission sample is processed for the first time using a step-cutting mode with a first ion beam voltage and current, a first cutting angle and a first cutting depth to form a first overall thinning region, which has a third preset thickness. The transmission sample is further processed a second time using a step-cutting mode with a second ion beam voltage and current, a first cutting angle and a second cutting depth to form the overall thinning region, which has a third preset thickness. The transmission sample is processed a third time using a third ion beam voltage and current, a first cutting angle, and a third cutting depth, so that the thickness of the overall thinned region reaches a first preset thickness. The third cutting depth is equal to the sum of the first cutting depth and the second cutting depth, and is less than the longitudinal width of the transmission sample. Wherein, the first cutting angle is 1.2 degrees, the third preset thickness is 500 nm, the first preset thickness is 300 nm, the first cutting depth, the second cutting depth and the third cutting depth are 4.5 μm, 1.5 μm and 6 μm respectively; the first ion beam voltage and current are 30 kV and 0.23 nA, the second ion beam voltage and current are 30 kV and 80 pA, and the third ion beam voltage and current are 30 kV and 40 pA; The overall thinning region of the transmission sample is thinned in sections using a focused ion beam to form at least two unit thin regions within the overall thinning region. The thickness of each unit thin region is less than a second preset thickness, the lateral width of each unit thin region is a first preset distance, and the interval between two adjacent unit thin regions is a second preset distance. The step of using a focused ion beam to perform zoned thinning of the overall thinning region of the transmission sample, to form at least two unit thin regions within the overall thinning region, includes: Using a fourth ion beam voltage and current, a first cutting angle, and a fourth cutting depth, at least two unit thin regions in the overall thinning region are processed for the first time to obtain at least two unit thin regions with a fourth preset thickness. Using the fifth ion beam voltage and current, the first cutting angle, and the fourth cutting depth, at least two unit thin regions in the overall thinning region are processed a second time to obtain at least two unit thin regions with a fifth preset thickness. Using a sixth ion beam voltage and current, a second cutting angle, and a fourth cutting depth, at least two unit thin areas in the overall thinning region are processed for the third time to obtain at least two unit thin areas with a sixth preset thickness. The second cutting angle is 3 degrees to form a reverse-cut structure. The operation sequence is to first thin the front side and then process the back side. Using a seventh ion beam voltage and current, a second cutting angle, and a fourth cutting depth, at least two unit thin regions in the overall thinning region are processed a fourth time to obtain at least two unit thin regions with a thickness less than a second preset thickness. The second cutting angle is 3 degrees.

2. The method according to claim 1, characterized in that, The fourth cutting depth is less than or equal to the third cutting depth.

3. The method according to claim 2, characterized in that, The second cutting angle is 3 degrees, and the second preset thickness, the fourth preset thickness, the fifth preset thickness and the sixth preset thickness are 10nm, 150nm, 100nm and 30nm respectively.

4. The method according to claim 3, characterized in that, The fourth ion beam voltage and current are 16KV and 23pA, the fifth ion beam voltage and current are 8KV and 21pA, the sixth ion beam voltage and current are 5KV and 7pA, and the seventh ion beam voltage and current are 2KV and 9pA.

5. The method according to claim 1, characterized in that, Before using a focused ion beam to thin the entire transmission sample, the method further includes: A protective layer is formed on the original surface of the transmission sample, the thickness of which is greater than 2.5 μm.

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