Sample preparation and detection method for analyzing trace elements in etched deep hole

Abstract

The invention belongs to the technical field of semiconductor detection, and provides a sample preparation and detection method for analyzing trace elements in an etched deep hole, and the sample preparation method comprises the following steps: depositing a first protective layer, gluing and plating a second protective layer on the surface of a deep hole groove sample to be detected in sequence to obtain a sample intermediate to be detected; performing first FIB cutting on the to-be-detected sample intermediate to obtain a target to-be-detected sample; placing the substrate end of the target sample to be detected upwards, and performing second FIB cutting on the substrate to obtain a TOF-SIMS sample; the TOF-SIMS sample comprises a whole deep hole groove and a substrate area, wherein the substrate area extends downwards from the bottom of the deep hole groove by 0.1-1 [mu] m. The prepared TOF-SIMS sample comprises the whole etched deep hole groove, analysis is started from the back face of the TOF-SIMS sample during detection, element information in the etched deep hole groove is comprehensively detected, the detection sensitivity is high, and the result is more accurate.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor detection, and relates to a sample preparation and detection method for trace element analysis in an etched deep hole. Background Art

[0002] With the rapid development of semiconductor devices toward three-dimensional integration and miniaturization, high-aspect-ratio etching (HARE) has become a key process in the manufacturing of core devices such as 3D NAND flash memory, dynamic random access memory (DRAM), and through-silicon vias (TSVs). However, due to the complexity of the plasma etching reaction and the special characteristics of high-aspect-ratio structures during HARE etching, the accumulation of etched residue elements has become an increasingly prominent problem, seriously affecting the electrical performance and reliability of the device.

[0003] Most current deep hole trench etching processes are based on reactive ion etching (RIE) technology using fluorine-based (such as CF4, C4F6) or chlorine-based (such as Cl2, BCl3) gas systems. During the etching process, reaction byproducts (such as fluorocarbon polymers, metal chlorides, etc.) tend to deposit on the sidewalls or bottom of the deep hole, forming residues. In addition, due to the uneven distribution of plasma inside the deep hole and limited etching gas transmission, residual elements (such as F, C, Cl, O, etc.) tend to be locally enriched. Therefore, quantitative analysis of the types, concentrations, and distributions of residual elements in the deep hole trench is crucial for process optimization.

[0004] Currently, a common method involves using a focused ion beam (FIB) to cross-section the deep holes, extracting transmission electron microscopy (TEM) lamellae for TEM observation, and then quantitatively analyzing the elemental distribution within the deep hole grooves using TEM-EDX analysis. However, TEM analysis suffers from several issues: First, sample preparation limitations: TEM lamellae can only analyze a single deep hole or a row of deep holes, with a lateral width of approximately a few microns, a vertical depth of several microns, and a thickness of approximately 100 nm. Etching process residues are often random, and each TEM sample can only analyze a single deep hole or a row of deep holes, failing to fully capture the full picture of the etching process. Therefore, multiple, multi-point tests are required to determine whether etching process residues remain within the deep hole grooves. Second, the detection range and sensitivity are limited. Due to the instrument's principle, TEM-EDX analysis can only detect elements 5 and later in the periodic table, excluding H, He, Li, and Be. Furthermore, the detection limit of TEM-EDX is at the order of 0.1 at.%, making it impossible to detect signals from residual elements at very low concentrations.

[0005] In summary, developing a sample preparation and detection method for trace element analysis in etched deep holes with high sensitivity and more accurate analysis results is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a sample preparation and detection method for trace element analysis in etched deep holes, which can comprehensively detect the element information in the etched deep hole grooves and quantitatively detect the content of trace elements in the deep hole grooves, and thus effectively analyze the changes in residual trace elements caused by different etching processes.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a sample preparation method for trace element analysis in an etched deep hole, the sample preparation method comprising the following steps:

[0009] (1) depositing a first protective layer, applying glue, and plating a second protective layer on the surface of a deep hole sample to be tested, to obtain an intermediate of the sample to be tested;

[0010] (2) performing a first FIB cutting on the intermediate of the sample to be tested in step (1) to obtain a target sample to be tested;

[0011] (3) placing the target sample to be tested in step (2) with the substrate end facing upward, performing a second FIB cutting on the substrate to obtain a TOF-SIMS (time-of-flight secondary ion mass spectrometry) sample;

[0012] The TOF-SIMS sample includes the entire deep hole groove and the substrate area extending 0.1-1 μm downward from the bottom of the deep hole groove, for example, it can be 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm or 0.9 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] The sample preparation method provided by the present invention sequentially deposits a first protective layer, applies glue, and plates a second protective layer on the surface of the deep hole groove sample to be measured, and combines this with two FIB cuttings to ensure that the prepared TOF-SIMS sample includes not only the entire deep hole groove, but also the substrate area 0.1-1μm below the bottom of the deep hole groove. The TOF-SIMS sample encompasses the entire etched deep hole groove, ensuring the accuracy and reliability of subsequent analysis and detection results.

[0014] It should be noted that depositing the first protective layer can not only prevent the ion beam from damaging the structure inside the deep hole groove, but also serve as a marking element for subsequent detection of the bottom of the deep hole groove; coating with glue can ensure that the deep hole groove is fully filled and the sample surface is flattened, while preventing the ion beam from damaging the surface structure of the deep hole groove; plating the second protective layer can not only prevent the ion beam from damaging the surface structure of the deep hole groove and avoid its deformation, but also serve as a sign of the end of the detection of the sample to be tested.

[0015] It should also be noted that the first FIB (focused ion beam) cutting was performed to cut out the entire deep hole groove and the base area of ​​the hole bottom, and then the second FIB cutting was used to further thin the sample after the first FIB cutting, ensuring the subsequent comprehensive and accurate evaluation of trace elements in the TOF-SIMS sample while shortening the sample preparation time and subsequent detection time.

[0016] As a preferred technical solution of the present invention, the surface of the deep hole sample to be measured in step (1) includes the inner surface and the upper surface of the deep hole to be measured.

[0017] Preferably, the deposition method in step (1) includes atomic layer deposition (ALD).

[0018] The present invention does not specifically limit the process parameters of atomic layer deposition, as long as a first protective layer with a thickness of 2-5 nm is deposited. Those skilled in the art can determine the process parameters based on actual production experience or existing technical methods.

[0019] Preferably, the thickness of the first protective layer in step (1) is 2-5 nm, for example, it can be 2.2 nm, 2.5 nm, 2.6 nm, 2.8 nm, 3 nm, 3.2 nm, 3.5 nm, 3.6 nm, 3.8 nm, 4 nm, 4.2 nm, 4.5 nm, 4.6 nm or 4.8 nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] It should be noted that controlling the thickness of the first protective layer facilitates accurate determination of the deep hole bottom position and provides a clear interface for TOF-SIMS depth analysis. If the first protective layer is too thin, TOF-SIMS signal sensitivity will be poor. By controlling the thickness of the first protective layer within the range of 2-5 nm, the signal-to-noise ratio of the collected secondary ion signal can be improved, making it more convenient to determine the hole bottom position.

[0021] Preferably, in step (1), the first protective layer comprises a hafnium oxide layer.

[0022] As a preferred technical solution of the present invention, the method of applying glue in step (1) includes applying glue and forming a glue layer after curing.

[0023] In the present invention, the glue comprises epoxy glue; the epoxy glue can be a single-component epoxy resin glue or a two-component epoxy resin glue, and those skilled in the art can select the appropriate one based on actual conditions. The present invention does not impose any specific restrictions on the curing process parameters, as long as the glue can be cured into a shape. Those skilled in the art can determine the appropriate curing process parameters based on actual production experience or existing technical methods.

[0024] Preferably, the adhesive layer fills the entire deep hole groove and covers the first protective layer.

[0025] As a preferred technical solution of the present invention, the method of coating the second protective layer in step (1) includes evaporation.

[0026] The present invention does not impose any specific limitation on the process parameters of the evaporation deposition, as long as the second protective layer is deposited to a thickness of 0.2-5 μm. Those skilled in the art can determine the process parameters based on actual production experience or existing technical methods.

[0027] Preferably, the thickness of the second protective layer in step (1) is 0.2-5 μm, for example, it can be 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm or 4.5 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] It should be noted that by controlling the thickness range of the second protective layer, it is ensured that the adhesive layer in the target area of ​​the sample will not be deformed under the focused ion beam, which is beneficial to improving the flatness of subsequent TOF-SIMS samples and enhancing the accuracy of sample preparation products.

[0029] Preferably, in step (1), the second protective layer comprises a platinum layer.

[0030] In the present invention, the second protective layer is arranged on the surface of the adhesive layer.

[0031] As a preferred technical solution of the present invention, the voltage of the first FIB cutting in step (2) is 25-35 kV, for example, it can be 26 kV, 27 kV, 28 kV, 29 kV, 30 kV, 31 kV, 32 kV, 33 kV or 34 kV, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, in step (2), the beam current of the first FIB cutting is 5-65nA, for example, it can be 10nA, 15nA, 20nA, 25nA, 30nA, 35nA, 40nA, 45nA, 50nA, 55nA or 60nA, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0033] Preferably, the target sample to be tested in step (2) includes the entire deep hole groove and the base area extending downward by at least 1 μm from the deep hole groove, for example, it can be 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm or 2 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] As a preferred technical solution of the present invention, the voltage of the second FIB cutting in step (3) is 25-35 kV, for example, it can be 26 kV, 27 kV, 28 kV, 29 kV, 30 kV, 31 kV, 32 kV, 33 kV or 34 kV, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] Preferably, the beam current of the second FIB cutting in step (3) is smaller than the beam current of the first FIB cutting in step (2).

[0036] Preferably, in step (3), the beam current of the second FIB cutting is 1-20nA, for example, it can be 2nA, 5nA, 6nA, 8nA, 10nA, 12nA, 15nA, 16nA or 18nA, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0037] Preferably, the base includes a substrate portion and / or a film layer portion.

[0038] As a preferred technical solution of the present invention, the flatness of the TOF-SIMS sample in step (3) is ≤20 nm, for example, it can be 18 nm, 16 nm, 15 nm, 12 nm, 10 nm, 8 nm, 6 nm or 4 nm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0039] In the present invention, the prepared TOF-SIMS sample has excellent flatness, which ensures that the depth of ions incident on the sample remains consistent during subsequent detection processes, thereby ensuring the accuracy and reliability of trace element analysis results.

[0040] In a second aspect, the present invention provides a method for detecting trace elements in an etched deep hole, the detection method comprising: placing a TOF-SIMS sample prepared by the sample preparation method described in the first aspect on a grid, fixing it, and performing analysis and detection;

[0041] The TOF-SIMS sample is placed with the base end facing upward and the second protective layer end facing downward.

[0042] The detection method provided by the present invention uses a TOF-SIMS instrument to detect trace elements in the etched deep hole, which can comprehensively detect the element information in the etched deep hole groove, has high detection sensitivity, and more accurate results.

[0043] As a preferred technical solution of the present invention, the analysis and detection instrument includes a TOF-SIMS instrument.

[0044] As a preferred technical solution of the present invention, during the analysis and detection, a TOF-SIMS instrument is used to perform depth analysis from the substrate end to the second protective layer end, and quantitatively analyze the trace elements in the TOF-SIMS sample.

[0045] It should be noted that starting the analysis from the back side (substrate side) of the TOF-SIMS sample, combined with the provision of first and second protective layers, allows accurate determination of the deephole bottom location and the end-of-test marker, yielding a depth-dependent distribution curve of residual elements within the deephole. Subsequently, using simultaneous testing of standard samples, quantitative analysis of residual elements is possible, effectively analyzing the variations in residual trace elements resulting from different etching processes.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The sample preparation method provided by the present invention sequentially deposits a first protective layer, applies glue, and plates a second protective layer on the surface of the deep hole groove sample to be measured, and combines two FIB cuttings to ensure that the prepared TOF-SIMS sample includes not only the entire deep hole groove, but also the substrate area 0.1-1 μm below the bottom of the deep hole groove. The TOF-SIMS sample encompasses the entire etched deep hole groove, thereby improving the accuracy and precision of sample preparation and thereby improving the success rate of sample preparation.

[0048] (2) The detection method provided by the present invention uses a TOF-SIMS instrument to detect trace elements in the etched deep hole, and starts the analysis from the back of the TOF-SIMS sample. Combined with the setting of the first protective layer and the second protective layer, the position of the bottom of the deep hole and the detection end mark can be accurately determined, and the element information in the etched deep hole groove can be fully detected. The detection sensitivity is high and the results are more accurate.

[0049] (3) The detection method provided by the present invention can also perform quantitative analysis of residual elements by synchronously measuring standard samples, thereby effectively analyzing the changes in residual trace elements caused by different etching processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the structure of the TOF-SIMS sample prepared in Example 1.

[0051] Among them, 1-etched deep hole groove, 2-residue, 3-first protective layer, 4-glue layer, 5-second protective layer, 6-substrate.

[0052] Figure 2 This is a diagram showing the depth analysis results of the TOF-SIMS sample prepared in Example 1. DETAILED DESCRIPTION

[0053] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0054] In the following examples and comparative examples, the epoxy glue is 610 series from Master Bond Company of the United States.

[0055] Example 1

[0056] This embodiment provides a sample preparation and detection method for trace element analysis in etched deep holes, the sample preparation method comprising the following steps:

[0057] (1) Atomic layer deposition is used to deposit a first protective layer with a thickness of 4 nm on the surface of the deep hole groove sample to be tested, and then epoxy glue is coated inside the deep hole groove and on the surface of the first protective layer. After curing, a glue layer is formed, and then a second protective layer with a thickness of 3 μm is deposited on the surface of the glue layer by evaporation to obtain a sample intermediate to be tested;

[0058] Wherein, the surface of the deep hole sample to be measured includes the inner surface and the upper surface of the deep hole to be measured;

[0059] The first protective layer is a hafnium oxide layer; the glue layer fills the entire deep hole groove and covers the first protective layer; the second protective layer is a platinum layer;

[0060] (2) Fixing the intermediate of the sample to be tested in step (1) on a copper grid, performing a first FIB cutting at a voltage of 30 kV and a current of 9 nA to obtain the target sample to be tested;

[0061] The target sample to be tested includes the entire deep hole groove and the base area extending 1.5 μm downward from the bottom of the deep hole groove;

[0062] (3) The target sample to be tested in step (2) was fixed on a copper grid and placed with the substrate end facing upward. The substrate was subjected to a second FIB cutting at a voltage of 30 kV and a current of 2 nA to obtain a TOF-SIMS sample (such as Figure 1 shown);

[0063] The TOF-SIMS sample includes the entire deep hole groove and a base area extending 0.5 μm downward from the bottom of the deep hole groove; the base includes a substrate portion and a film layer portion.

[0064] The detection method includes: fixing a copper grid carrying a TOF-SIMS sample on a TOF-SIMS sample holder, placing the TOF-SIMS sample with the base end facing upward and the second protective layer end facing downward, and then using a TOF-SIMS instrument to perform depth analysis from the base end to the second protective layer end in sequence, and combining with simultaneous testing of a standard sample to obtain a detection result.

[0065] In this embodiment, the detection results of TOF-SIMS samples are as follows: Figure 2 As shown by Figure 2 It can be seen that the element information in the etched deep hole groove can be fully reflected. The total content of trace element fluorine (F) in the etched deep hole groove is 0.63%, which is helpful for analyzing the changes in residual trace elements caused by different etching processes.

[0066] Example 2

[0067] This embodiment provides a sample preparation and detection method for trace element analysis in etched deep holes, the sample preparation method comprising the following steps:

[0068] (1) Atomic layer deposition is used to deposit a first protective layer with a thickness of 2 nm on the surface of the deep hole groove sample to be tested, and then epoxy glue is coated inside the deep hole groove and on the surface of the first protective layer. After curing, a glue layer is formed, and then a second protective layer with a thickness of 5 μm is deposited on the surface of the glue layer by evaporation to obtain a sample intermediate to be tested;

[0069] Wherein, the surface of the deep hole sample to be measured includes the inner surface and the upper surface of the deep hole to be measured;

[0070] The first protective layer is a hafnium oxide layer; the glue layer fills the entire deep hole groove and covers the first protective layer; the second protective layer is a platinum layer;

[0071] (2) Fixing the intermediate of the sample to be tested in step (1) on a copper grid, performing a first FIB cutting at a voltage of 30 kV and a current of 15 nA to obtain the target sample to be tested;

[0072] The target sample to be tested includes the entire deep hole groove and the film layer area extending 1.1 μm downward from the bottom of the deep hole groove;

[0073] (3) Fixing the target sample to be tested in step (2) on a copper grid and placing the film layer end upward, performing a second FIB cutting on the film layer at a voltage of 30 kV and a current of 1 nA to obtain a TOF-SIMS sample;

[0074] The TOF-SIMS sample includes the entire deep hole groove and the film layer area extending 0.2 μm downward from the bottom of the deep hole groove.

[0075] The detection method includes: fixing a copper grid carrying a TOF-SIMS sample on a TOF-SIMS sample holder, placing the TOF-SIMS sample with the film layer end facing upward and the second protective layer end facing downward, and then using a TOF-SIMS instrument to perform depth analysis from the film layer end to the second protective layer end in sequence, and combining with simultaneous testing of a standard sample to obtain the detection results.

[0076] In this embodiment, the detection results can fully reflect the element information in the etched deep hole groove. The total content of trace element fluorine (F) in the etched deep hole groove is 0.62%, which is helpful for analyzing the changes in residual trace elements caused by different etching processes.

[0077] Example 3

[0078] This embodiment provides a sample preparation and detection method for trace element analysis in etched deep holes, the sample preparation method comprising the following steps:

[0079] (1) Atomic layer deposition is used to deposit a first protective layer with a thickness of 5 nm on the surface of the deep hole groove sample to be tested, and then epoxy glue is coated inside the deep hole groove and on the surface of the first protective layer. After curing, a glue layer is formed, and then a second protective layer with a thickness of 1 μm is deposited on the surface of the glue layer by evaporation to obtain a sample intermediate to be tested;

[0080] Wherein, the surface of the deep hole sample to be measured includes the inner surface and the upper surface of the deep hole to be measured;

[0081] The first protective layer is a hafnium oxide layer; the glue layer fills the entire deep hole groove and covers the first protective layer; the second protective layer is a platinum layer;

[0082] (2) Fixing the intermediate of the sample to be tested in step (1) on a copper grid, performing a first FIB cutting at a voltage of 30 kV and a current of 10 nA to obtain the target sample to be tested;

[0083] The target sample to be tested includes the entire deep hole groove and the base area extending 1.4 μm downward from the bottom of the deep hole groove;

[0084] (3) Fixing the target sample to be tested in step (2) on a copper grid and placing it with the substrate end facing upward, performing a second FIB cutting on the substrate at a voltage of 30 kV and a current of 3 nA to obtain a TOF-SIMS sample;

[0085] The TOF-SIMS sample includes the entire deep hole groove and a base region extending 0.3 μm downward from the bottom of the deep hole groove; the base includes a substrate portion and a film layer portion.

[0086] The detection method is carried out with reference to Example 1.

[0087] In this embodiment, the detection results can fully reflect the element information in the etched deep hole groove. The total content of trace element fluorine (F) in the etched deep hole groove is 0.65%, which is helpful for analyzing the changes in residual trace elements caused by different etching processes.

[0088] Example 4

[0089] This embodiment provides a sample preparation and detection method for trace element analysis in etched deep holes, except that the thickness of the first protective layer in step (1) is 1 nm; other conditions are the same as those in Example 1.

[0090] In this embodiment, since the first protective layer is too thin, it is impossible to accurately determine the position of the bottom of the deep hole and whether residual elements remain at the bottom of the hole, which affects the accuracy of the detection result.

[0091] Example 5

[0092] This embodiment provides a sample preparation and detection method for trace element analysis in etched deep holes, except that the thickness of the first protective layer in step (1) is 20 nm; other conditions are the same as those in Example 1.

[0093] In this embodiment, although the first protective layer is too thick and has no significant impact on the detection results, the time for depositing the first protective layer is too long, which affects the sample preparation efficiency.

[0094] Example 6

[0095] This embodiment provides a sample preparation and detection method for trace element analysis in etched deep holes, except that the thickness of the second protective layer in step (1) is 0.2 μm; other conditions are the same as those in Example 1.

[0096] In this embodiment, because the second protective layer is too thin, the adhesive layer is easily deformed during cutting, resulting in a decrease in the flatness of the TOF-SIMS sample and some inaccuracy in judging the end point of the test. The signal of the TOF-SIMS depth analysis at the end point of the sample will be somewhat abnormal, affecting the accuracy of the detection results.

[0097] Example 7

[0098] This embodiment provides a sample preparation and detection method for trace element analysis in etched deep holes, except that the thickness of the second protective layer in step (1) is 10 μm; other conditions are the same as those in Example 1.

[0099] In this embodiment, although the second protective layer is too thick and has no significant impact on the test results, the time for plating the second protective layer is too long, which affects the sample preparation efficiency.

[0100] Example 8

[0101] This embodiment provides a sample preparation and detection method for trace element analysis in deep etched holes, except that the beam current of the first FIB cutting in step (2) is 40nA and the beam current of the second FIB cutting in step (3) is 25nA; other conditions are carried out with reference to Example 1.

[0102] In this embodiment, if the beam current of the second FIB cutting is too large, the TOF-SIMS sample flatness is not ideal, and the depth resolution during TOF-SIMS depth analysis is affected, and the film layer structure is confused.

[0103] Example 9

[0104] This embodiment provides a sample preparation and detection method for trace element analysis in etched deep holes, except that the beam current of the second FIB cutting in step (3) is 0.5nA; other conditions are the same as those in Example 1.

[0105] In this embodiment, if the beam current of the second FIB cutting is too small, the thinning time is too long, resulting in the TOF-SIMS sample flatness not meeting the requirements, which in turn affects the TOF-SIMS depth resolution.

[0106] Comparative Example 1

[0107] This comparative example provides a sample preparation and detection method for trace element analysis in etched deep holes, except that the first protective layer is not deposited in step (1); other conditions are the same as those in Example 1.

[0108] In this comparative example, if the first protective layer is not deposited, it is impossible to accurately determine the position of the bottom of the deep hole, and further it is impossible to determine whether residual elements remain at the bottom of the hole.

[0109] Comparative Example 2

[0110] This comparative example provides a sample preparation and detection method for trace element analysis in etched deep holes, except that step (2) is not performed; other conditions are the same as those in Example 1.

[0111] In this comparative example, if only the second FIB cutting is performed, the thinning time is also too long, resulting in the TOF-SIMS sample flatness not meeting the requirements, and further affecting the TOF-SIMS depth resolution.

[0112] Comparative Example 3

[0113] This comparative example provides a sample preparation and detection method for trace element analysis in etched deep holes, except that step (3) is not performed; other conditions are the same as those in Example 1.

[0114] In this comparative example, if only the first FIB cutting is performed, the back area of ​​the TOF-SIMS sample is too large. When the TOF-SIMS depth analysis reaches the position of interest, the roughness of the surface to be measured is too large due to the long-term ion sputtering, and the TOF-SIMS depth analysis curve with high depth resolution cannot be effectively obtained. In addition, the film layer information may be confused due to the deterioration of the depth resolution, and the bottom position of the hole cannot be accurately determined.

[0115] Comparative Example 4

[0116] This comparative example provides a sample preparation and detection method for trace element analysis in etched deep holes. Except that the second protective layer end of the TOF-SIMS sample is placed upward and the substrate end is placed downward during detection, other conditions are the same as those in Example 1.

[0117] In this comparative example, if the analysis starts from the front of the TOF-SIMS sample, the film structure information is unclear due to the complex surface structure of the sample, and the position of the pore bottom and the position of the residue cannot be accurately determined.

[0118] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A sample preparation method for trace element analysis in etched deep holes, characterized in that: The sample preparation method comprises the following steps: (1) depositing a first protective layer, applying glue, and plating a second protective layer on the surface of a deep hole sample to be tested, to obtain an intermediate of the sample to be tested; (2) performing a first FIB cutting on the intermediate of the sample to be tested in step (1) to obtain a target sample to be tested; (3) placing the target sample to be tested in step (2) with the substrate end facing upward, and performing a second FIB cutting on the substrate to obtain a TOF-SIMS sample; The TOF-SIMS sample includes the entire deep hole groove and a substrate area extending 0.1-1 μm downward from the bottom of the deep hole groove.

2. The sample preparation method according to claim 1, characterized in that The surface of the deep hole sample to be measured in step (1) includes the inner surface and the upper surface of the deep hole to be measured; And / or, the deposition method in step (1) includes atomic layer deposition; And / or, in step (1), the thickness of the first protective layer is 2-5 nm; And / or, in step (1), the first protective layer includes a hafnium oxide layer.

3. The sample preparation method according to claim 1 or 2, characterized in that: The method of applying glue in step (1) includes applying glue and forming a glue layer after curing; And / or, the adhesive layer fills the entire deep hole groove and covers the first protective layer.

4. The sample preparation method according to claim 1, characterized in that The method of depositing the second protective layer in step (1) includes evaporation; And / or, the thickness of the second protective layer in step (1) is 0.2-5 μm; And / or, in step (1), the second protective layer includes a platinum layer.

5. The sample preparation method according to claim 1, characterized in that: Step (2) The voltage of the first FIB cutting is 25-35 kV; and / or, in step (2), the beam current of the first FIB cutting is 5-65 nA; And / or, the target sample to be tested in step (2) includes the entire deep hole groove and the base area extending downward from the deep hole groove by at least 1 μm.

6. The sample preparation method according to claim 1, characterized in that: Step (3) The voltage of the second FIB cutting is 25-35 kV; and / or, the beam current of the second FIB cutting in step (3) is smaller than the beam current of the first FIB cutting in step (2); and / or, in step (3), the beam current of the second FIB cutting is 1-20 nA; And / or, the base includes a substrate portion and / or a film layer portion.

7. The sample preparation method according to claim 1, characterized in that: The flatness of the TOF-SIMS sample in step (3) is ≤20nm.

8. A method for detecting trace elements in etched deep holes, characterized in that: The detection method comprises: placing a TOF-SIMS sample prepared by the sample preparation method according to any one of claims 1 to 7 on a grid, fixing the sample and performing analysis and detection; The TOF-SIMS sample is placed with the base end facing upward and the second protective layer end facing downward.

9. The detection method according to claim 8, characterized in that The instrument for analysis and detection includes a TOF-SIMS instrument.

10. The detection method according to claim 8, characterized in that During the analysis and detection, a TOF-SIMS instrument is used to perform depth analysis from the substrate end to the second protective layer end, and to quantitatively analyze the trace elements in the TOF-SIMS sample.

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