High aspect ratio micro-hole standard sample and its preparation and characterization method

Abstract

The present invention relates to a high-aspect-ratio micro-hole groove standard template and its preparation and characterization method. The characterization method includes: imaging the aperture plane of the micro-hole groove to be sliced, extracting the edge contour of the micro-hole groove aperture, and calculating the reference diameter of the micro-hole groove to be sliced; performing preliminary cutting of the standard template along the macro-marking line to obtain a primary slice; grinding along the macro-marking line until stopping at the medium-size marking line to obtain a secondary slice; using the medium-size marking line as the cutting path and the reference diameter as the target diameter, grinding the secondary slice layer by layer to obtain a prepared surface of the diameter section; obtaining the measured value of the prepared surface; and establishing a spatial geometric deviation model for characterizing the deviation between the prepared surface and the ideal surface of the diameter section based on the measured value and the reference diameter, performing error compensation on the measured value, and converting the measured value into the equivalent value of the ideal surface. The characterized standard template can meet the precise calibration requirements of non-destructive measurement instruments and equipment for high-aspect-ratio micro-hole grooves.

Description

Technical Field

[0001] The present invention relates to the field of nano-metrology technology, in particular to a high aspect ratio micro-hole groove standard sample and a preparation and characterization method thereof. Background Art

[0002] High aspect ratio microstructures are a typical structural design in semiconductor micro-nanofabrication technology. They are characterized by a ratio of longitudinal depth to lateral linewidth greater than 10:1, with linewidths ranging from a few μm to tens of μm and depths reaching 300 μm or more. Using corresponding standard templates to create standards can resolve the issues of inconsistent linewidth and depth parameter scales and traceability across various types of measuring instruments and equipment. This ensures accurate and reliable measurement results for critical dimensions such as linewidth and depth across different measuring instruments and equipment when measuring high aspect ratio microstructures such as MEMS devices and TSVs in the semiconductor industry.

[0003] Before use, standard samples must be characterized (or calibrated). This involves determining the dimensional parameters of the microstructures on the standard sample. The parameters to be measured for high aspect ratio microstructures are width (diameter) and depth. International standards use two characterization methods to describe these parameters. High aspect ratio microstructures primarily include grooves and holes, and corresponding standard samples also include grooved and hole-grooved structures.

[0004] At present, metrology institutions and standard sample companies at home and abroad have developed a large variety of step and groove standard samples and corresponding characterization schemes. For the characterization of open groove structures, the line width parameters can be obtained by cutting at any vertical cross section. However, for deep hole groove structures, reliable aperture parameters can only be obtained by precise cutting along the diameter direction of the hole. Due to the structural characteristics of deep hole grooves with small openings, large depths, and non-open types, it is currently impossible to use conventional measuring instruments to perform synchronous and direct high-precision characterization of their diameters and hole groove depths. In addition, during the preparation process of deep hole grooves, there are problems with hole mouth expansion and uneven depth etching caused by lateral etching, resulting in a lack of accurate characterization of the structural dimensions. Therefore, the characterization of deep hole grooves faces complex technical challenges.

[0005] In summary, there is still a lack of effective characterization solutions for high aspect ratio micro-hole structures, which cannot meet the precise calibration requirements of non-destructive measurement instruments and equipment for high aspect ratio micro-holes in the semiconductor field. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention aims to provide a high aspect ratio micro-hole groove standard sample and its preparation and characterization method.

[0007] The technical solution adopted in the present invention is as follows:

[0008] The present invention provides a method for characterizing a standard template of a micro-hole groove with a high aspect ratio. A plurality of the standard templates are formed on a single wafer. The standard template is provided with a tracking structure and a micro-hole groove to be sliced. The characterization method comprises the following steps:

[0009] Set parallel macro marking lines and medium size marking lines. The distance from the edge of the micro-hole slot to be sliced ​​to the macro marking line is l 1. The distance to the middle size mark line is l 2, l 1> l 2;

[0010] The tracking structure is used to locate the aperture plane of the microporous groove to be sliced, and the aperture edge contour of the microporous groove in the image is extracted. The reference diameter of the microporous groove to be sliced ​​is obtained by binarization processing and least squares circle fitting;

[0011] Performing a preliminary cutting of the standard template along the macro marking line to preliminarily thin the area between the edge of the microporous slot to be sliced ​​and the edge of the standard template to obtain a single slice;

[0012] On the primary slice, grinding is performed along the macroscopic marking line until it reaches the medium-sized marking line, thereby obtaining a secondary slice;

[0013] Using the middle size mark line as the cutting path and the reference diameter as the target diameter, the secondary slice is ground layer by layer to obtain a preparation surface of the microporous groove diameter section to be sliced;

[0014] Measure and obtain the measured values ​​of the prepared surface, which include the depth, top width, and half-height full width of the microporous groove, where the half-height full width is the width of the microporous groove at half the depth;

[0015] Based on the measured value and the reference diameter, a spatial geometric deviation model is established to characterize the position deviation between the prepared surface and the ideal surface of the diameter profile. The measured value is error compensated based on the position deviation to convert the measured value into an equivalent value of the ideal surface.

[0016] Further technical solutions are:

[0017] The performing error compensation on the measured value based on the position deviation includes:

[0018] Calculate the vertical distance between the prepared surface and the ideal surface of the diameter section d : ;

[0019] Where, D T The reference diameter、L T is the measured top width;

[0020] The measured value of the full width at half maximum L Convert to equivalent value of ideal surface D : .

[0021] The micro-hole grooves to be sliced ​​on the standard template at multiple positions of the wafer are characterized to obtain multiple equivalent values ​​and calculate the average value as the final characterization result.

[0022] The nominal size of the microporous groove to be sliced ​​is 10 μm; l 1 = 200 μm to 300 μm; l 2=20 μm±2 μm.

[0023] The preliminary cutting is performed using a DISCO dicing machine; and the grinding is performed using an ultra-precision mechanical grinding process.

[0024] The method of setting mutually parallel macro marking lines and medium-sized marking lines includes:

[0025] Corresponding cutting parameters are set in the cutting and grinding equipment, or corresponding physical marks are set on the standard template.

[0026] The imaging, layer-by-layer grinding and measurement were performed using a FIB system.

[0027] The present invention also provides a high aspect ratio micro-hole groove standard sample, the standard sample is prepared by semiconductor technology;

[0028] The standard sample adopts the characterization method to determine the size parameters of the high aspect ratio micro-hole groove.

[0029] The standard sample plate is also provided with a calibration micro-hole groove, which has the same structure and size parameters as the micro-hole groove to be sliced.

[0030] The present invention also provides a method for preparing the high aspect ratio micro-hole groove standard template, comprising:

[0031] preparing an SOI substrate;

[0032] Disposing a metal hard mask layer on the SOI substrate;

[0033] Disposing a photoresist layer on the metal hard mask layer and forming a pattern area by photolithography;

[0034] Performing deep silicon etching on the metal hard mask layer and the SOI substrate along a depth direction through the pattern area;

[0035] The metal hard mask layer and the photoresist layer are removed.

[0036] The beneficial effects of the present invention are as follows:

[0037] The characterization method of this invention utilizes two marking lines for macro- and mesoscale positioning, facilitating rapid mechanical removal of large-scale materials and preventing stress damage to the pore structure caused by close proximity during secondary cutting. Furthermore, combined with the high positioning accuracy of FIB technology, the prepared surface with a precise diameter profile can be precisely prepared in a small area, ensuring the integrity and surface quality of the prepared surface. This balances processing efficiency and quality.

[0038] The characterization method of the present invention constructs a spatial geometric deviation model to characterize the position deviation between the ideal surface of the diameter section and the preparation surface, eliminates the measurement error caused by the preparation surface offset through the method of geometric compensation, and finally achieves high-precision characterization of key dimensions.

[0039] When the present invention adopts semiconductor technology to prepare the standard template of aspect ratio micro-hole groove, the problem of hole expansion and uneven depth etching caused by lateral etching is solved by setting a metal hard mask, ensuring the standard of hole groove structure, and providing an accurate basis for subsequent characterization of key dimensions.

[0040] The standard sample characterized by the present invention provides a carrier for measuring the physical object for on-site calibration of non-destructive measuring instruments and equipment for micro-holes with high aspect ratios in the semiconductor field.

[0041] Other features and advantages of the present invention will be set forth in the following description or may be learned by practicing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the process of the characterization method according to an embodiment of the present invention.

[0043] Figure 2 This is a schematic diagram of the planar structure of a single standard template according to an embodiment of the present invention.

[0044] Figure 3 Schematic diagram of the spatial geometric deviation model according to an embodiment of the present invention.

[0045] Figure 4 These are the SEM measurement results of the full width at half maximum and top width of the surface prepared in the embodiment of the present invention.

[0046] Figure 5 These are the SEM measurement results of the depth of the surface prepared in the examples of the present invention.

[0047] Figure 6 This is the SEM measurement result of the reference diameter of the embodiment of the present invention.

[0048] Figure 7Schematic diagram of the structure of a single wafer according to an embodiment of the present invention.

[0049] Figure 8 This is a schematic diagram of the result of characterizing a first-size sample according to an embodiment of the present invention.

[0050] Figure 9 This is a schematic diagram of the result of characterizing a second-size sample according to an embodiment of the present invention.

[0051] Figure 10 This is the non-destructive measurement result of the first size sample in an embodiment of the present invention.

[0052] Figure 11 This is the non-destructive measurement result of the second size sample in an embodiment of the present invention.

[0053] Figure 12 Schematic diagram of the process for preparing a standard sample of micro-holes with a high aspect ratio according to an embodiment of the present invention.

[0054] Figure 13 for Figure 7 An enlarged view of a single standard sample.

[0055] Figure 14 for Figure 13 Enlarged views of parts A and B in the middle.

[0056] In the figure: 1. Standard sample; 2. Macro mark line; 3. Medium size mark line; 4. Wafer; 10. Tracking structure; 11. Micro-hole slot to be sliced; 12. Calibration micro-hole slot. DETAILED DESCRIPTION

[0057] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0058] Example 1

[0059] This embodiment provides a method for characterizing a high aspect ratio micro-hole standard template. Multiple standard templates are formed on a single wafer. Figure 2 Each standard sample 1 is provided with a tracking structure 10 and a microporous groove 11 to be sliced. A macro marking line 2 and a medium-sized marking line 3 are set parallel to each other. The distance from the edge of the microporous groove to be sliced ​​to the macro marking line is l 1. The distance to the middle size mark line is l 2, l 1> l 2.

[0060] As a preferred embodiment, the nominal size of the microporous groove to be sliced ​​in this embodiment is 10 μm in diameter and 100 μm or 200 μm in depth; l 1 preferably takes 200 μm to 300 μm; l2 is preferably 20 μm±2 μm.

[0061] See also Figure 1 , the characterization method comprises the following steps:

[0062] S1. Quickly and accurately find the microporous groove to be sliced ​​by positioning the tracking structure; perform high-resolution imaging on the orifice plane of the microporous groove to be sliced, extract the edge contour of the microporous groove orifice in the image, and obtain the reference diameter of the microporous groove to be sliced ​​by binarization and least squares circle fitting of the edge contour.

[0063] As a preferred method, a high-aspect-ratio micropore standard template is mounted on a focused ion beam (FIB) stage to ensure a smooth surface. Plasma cleaning is used to remove surface contaminants, providing a clean surface for subsequent processing. High-resolution imaging of the micropore structure is performed using the FIB system's SEM (scanning electron microscope).

[0064] S2. Preliminary cutting is performed on the standard template along the macro marking line to preliminarily thin the area between the edge of the microporous slot to be sliced ​​and the edge of the standard template to obtain a slice.

[0065] Among them, the macro marking line is used for positioning the initial cutting. Since it is far away from the micro-hole slot orifice, it is convenient to use mechanical cutting to perform preliminary cutting, and the overall processing efficiency is improved by removing large-scale materials.

[0066] As a preferred method, a DISCO dicing machine is used for the preliminary cutting. This method does not require SEM real-time imaging monitoring and can achieve one-time cutting by setting corresponding cutting parameters, which has the advantage of high efficiency.

[0067] S3. Grind along the macro-marked line on the primary slice and stop at the medium-sized marked line to obtain a secondary slice.

[0068] Among them, the medium size marking line is used for further fine positioning to control the finishing allowance. Since it has a certain distance from the micro-hole slot orifice, it is preferred to use ultra-precision mechanical grinding process for the grinding. Considering that there is no SEM real-time imaging monitoring during the grinding process, the remaining processing amount is l 2 is set to 20 μm ± 2 μm from the edge of the hole slot. This can improve efficiency while avoiding the problem of stress damage to the hole slot structure caused by too close a distance.

[0069] As a preferred embodiment, the setting of the macro marking lines and the medium-sized marking lines includes:

[0070] The corresponding parameters are set in the DISCO dicing machine and ultra-precision mechanical grinding process, and the equipment directly performs positioning cutting and grinding along the set position or distance parameters.

[0071] Alternatively, corresponding physical marks are set on the standard template, and cutting, grinding and advancing are performed along the physical marks under the monitoring of a scanning electron microscope.

[0072] S4, using the middle size mark line as the cutting path and the reference diameter as the target diameter, performing layer-by-layer grinding on the secondary slice to obtain a preparation surface of the microporous groove diameter section to be sliced.

[0073] As a preferred method, a FIB system is used to optimize the ion beam scanning trajectory and etching parameters, performing high-precision iterative grinding. The micropores are continuously sectioned longitudinally, and the grinding progress is monitored in real time using a SEM to ensure positioning accuracy. During the layer-by-layer grinding process, the top width of the resulting longitudinal section is continuously measured to ensure that it approaches the reference diameter, thereby obtaining the prepared surface of the diameter section.

[0074] Because FIB technology offers extremely high positioning accuracy, it can precisely prepare observation surfaces in tiny areas while minimizing processing stress, ensuring cross-sectional integrity and surface quality. However, its processing efficiency is low, making it suitable only for fine processing. Therefore, this embodiment utilizes FIB-based cutting only in step S4, while mechanical cutting with a dicing machine is used in steps S2 and S3, thereby improving overall processing efficiency.

[0075] S5. Measure and obtain the measured values ​​of the prepared surface, which include the depth, top width, and half-height full width of the microporous groove, where the half-height full width is the width of the microporous groove at half the depth.

[0076] Specifically, key geometric parameters such as the depth, top width, bottom width, and full width at half maximum of the prepared surface were measured using SEM. This embodiment refers to the definitions in ISO 25178-70-2014 and GB / T 19067.1-2003, with the diameter of the pore structure measured at the center (50% of the pore depth) being used as the diameter, and the full width at half maximum being used as the characteristic value.

[0077] S6. Based on the measured value and the reference diameter, a spatial geometric deviation model is established for characterizing the position deviation between the prepared surface and the ideal surface of the diameter section. Figure 3 As shown, the measured value is error compensated based on the position deviation, and the measured value is converted into an equivalent value of the ideal surface.

[0078] During the preparation of the prepared surface, even though this embodiment employs a "three-level precision control" preparation method of initial cutting, grinding advancement, and layer-by-layer grinding, under-grinding or over-grinding may still occur. Therefore, this embodiment uses error compensation to further correct and map the measured values ​​of the prepared surface to the ideal surface to improve the accuracy of the characterization.

[0079] See also Figure 3 The green cross section represents the prepared surface, and the blue cross section represents the ideal surface. The ideal surface is the cross section obtained by cutting along the reference diameter under ideal conditions. There is a position deviation between the prepared surface and the ideal surface, and the vertical distance between the two is d According to the preparation process of the preparation surface, the distance d The values ​​at the hole opening and 50% depth are consistent. Therefore, based on the spatial geometric deviation model, the measured values ​​are compensated for errors, including:

[0080] Calculate the vertical distance between the prepared surface and the ideal surface of the diameter section d : (1)

[0081] Where, D T The reference diameter 、L T is the measured top width;

[0082] The measured value of the full width at half maximum L Convert to the equivalent value of the ideal surface D : (2)

[0083] in, D That is the calibration value of the half-height full width of the micro-hole groove to be sliced ​​on a single standard sample obtained by characterization.

[0084] Through geometric compensation, the measured data is converted into the equivalent full width at half maximum of the ideal surface of the hole groove, thereby eliminating the characterization error introduced by the cross-section preparation deviation. In this embodiment, a standard sample with a micro-hole groove with a nominal diameter of 10 μm and a depth of 200 μm (i.e., an aspect ratio of 20:1) is used as an example. The hole plane of the micro-hole groove to be sliced ​​is imaged using SEM, and the edge contour is extracted to obtain the measurement result of the reference diameter of 12.75 μm. Figure 6 The prepared surface of the micropore groove diameter section was measured by SEM, and the measurement results of the half-height full width and top width are shown in Figure 4 The depth measurement results are shown in Figure 5As shown in the figure, the measured values ​​of the full width at half maximum, top width, and depth are 10.05 μm, 12.39 μm, and 202.60 μm, respectively. According to formula (2), the calibrated value of the full width at half maximum of the microporous groove structure is 10.43 μm.

[0085] See also Figure 2 The standard sample plate of this embodiment is also provided with a calibration microporous slot 12, which has the same structure and dimensional parameters as the microporous slot 11 to be sliced ​​(it can be understood that the two are essentially the same, but with different names). The characterization results of the microporous slot 11 to be sliced ​​can be directly used to calibrate the microporous slot 12 without destroying the structure of the calibration microporous slot 12. Figure 7 、 Figure 13 and Figure 14 As shown, in the actual processed products, each wafer 4 is designed with several standard templates 1, each standard template 1 is provided with two micro-hole slots 11 to be sliced ​​and four calibration micro-hole slots 12, respectively. Figure 14 As shown in (a) and (b). Figure 14 (a) is Figure 13 Enlarged view of part A in the middle Figure 14 (b) is Figure 13 Enlarged view of section B in the middle. Because the hole depth and diameter of a single standard sample 1 are indirectly measured, rather than directly, by measuring the microvias to be sliced, structural dimensional differences between different microvias 11 to be sliced, as well as between a microvia 11 to be sliced ​​and a calibration microvia 12, will affect the characterization results. This effect is compensated for by calculating the arithmetic mean, and the effectiveness of this method is verified by measuring the structural uniformity of the sample on wafer 4.

[0086] As a preferred method, this embodiment selects five standard templates with relatively uniform spatial distribution of measurement positions on the wafer 4, and then measures the two micro-hole grooves 11 to be sliced, A and B, on each standard template 1, to obtain the characterization results of ten micro-hole grooves to be sliced, and then uses the range method to calculate and evaluate. For the standard template with a nominal value of a hole groove diameter of 10 μm and a hole groove depth of 100 μm (hereinafter referred to as the first size template), after characterization, the hole groove diameter and depth are as follows Figure 8 As shown in (a) and (b). The arithmetic mean of the hole diameter is 10.06 μm, and the uniformity deviation is 0.06 μm; the arithmetic mean of the hole depth is 102.65 μm, and the uniformity deviation is 0.50 μm. For the standard sample with a nominal hole diameter of 10 μm and a hole depth of 200 μm (hereinafter referred to as the second size sample), after characterization, the hole diameter and depth are as follows Figure 9As shown in (a) and (b), the arithmetic mean of the hole diameter is 10.43 μm, with a uniformity deviation of 0.06 μm; the arithmetic mean of the hole depth is 202.59 μm, with a uniformity deviation of 0.40 μm. Overall, the uniformity of the hole width is less than 0.6%, and the uniformity of the hole depth is less than 0.5%, indicating that each sample has good uniformity. Furthermore, the characterization method of this example can be effectively applied to actual products.

[0087] In order to verify the effectiveness of the characterization method of this embodiment, the first size sample and the second size sample are non-destructively measured using the existing non-destructive measurement system, and the results are as follows: Figure 10 、 Figure 11 The non-destructive measurement results were compared with the calibration values ​​obtained by the characterization method of this embodiment. The comparison results are shown in Table 1.

[0088] Table 1 Comparison of the measurement results of the existing non-destructive measurement system and the calibration values ​​determined by the characterization method of this embodiment

[0089]

[0090] like Figure 10 As shown in Table 1, the measured value of the hole diameter of the first size sample is 10.28 μm, and the deviation from the calibration value is 0.22 μm; the measured value of the hole depth is 102.90 μm, and the deviation from the calibration value is 0.25 μm.

[0091] like Figure 11 As shown in Table 1, the measured value of the hole diameter of the second size sample is 10.64 μm, which deviates from the calibration value by 0.21 μm, and the measured value of the hole depth is 202.78 μm, which deviates from the calibration value by 0.19 μm.

[0092] It can be seen that the non-destructive test results are basically consistent with the characterization and calibration results of the sample, which realizes the calibration of the instrument and verifies the effectiveness of the method of this embodiment.

[0093] Among them, the existing non-destructive measurement system is a near-infrared broadband interferometry microscopy measurement system proposed by Nanjing University of Science and Technology. This system fully utilizes the penetrating properties of near-infrared light for silicon-based materials. Through adaptive compensation technology for the aberration derived from the modulation of the probe light by a high aspect ratio structure, the high-throughput probe light is refocused on the bottom of the high aspect ratio microstructure pore groove. The three-dimensional morphology of the high aspect ratio microstructure is obtained through microscopic interference, and characteristic parameters such as width (diameter) and depth are then extracted from it. The spatial resolution is high and detailed information on the line width and depth of multiple sampling data points can be obtained. In the specific measurement process, the calibration pore groove structure is found through the positioning angle structure and the orthogonal scanning calibration structure, and the width and depth of the high aspect ratio micropore groove are tested using the near-infrared broadband interferometry microscopy measurement system. The specific structure and detailed measurement method of this measurement system are both existing technologies and will not be repeated here.

[0094] Example 2

[0095] This embodiment provides a standard sample of a micro-hole with a high aspect ratio, and the standard sample uses the characterization method described in Example 1 to determine the size parameters of the micro-hole with a high aspect ratio; the standard sample is prepared using a semiconductor process.

[0096] Example 3

[0097] See also Figure 12 This embodiment provides a method for preparing a standard sample plate of micro-holes with a high aspect ratio as described in Example 2, comprising the following steps:

[0098] (1) Preparation of SOI (Silicon-On-Insulator) substrate, specifically including:

[0099] Using a double-sided polished silicon wafer as the substrate, a 50 nm SiO2 layer is thermally grown on the surface and then bonded to form the SOI structure. The etch-stop properties of SiO2 ensure a flat bottom surface for the trenches, significantly improving the accuracy of deep trench machining.

[0100] (2) Providing a metal hard mask layer on the SOI substrate, specifically comprising:

[0101] Alternatively, first, the side of the SOI substrate where the metal hard mask layer is to be provided is ground and thinned;

[0102] Then, a 100 nm thick metal Cr layer is preferably evaporated on the SOI wafer by magnetron sputtering.

[0103] Compared with the photoresist mask, the metal hard mask used in this embodiment has better lateral etching resistance, can effectively suppress the problems of aperture expansion and uneven depth etching caused by lateral etching, and ensure stable control of extreme size structures with high aspect ratio.

[0104] (3) A photoresist layer is provided on the metal hard mask layer, and a pattern area is formed by photolithography.

[0105] As a preferred method, in response to the special requirements of deep silicon etching for mask thickness, a positive photoresist was used to expose a 10 μm diameter circular hole pattern while maintaining a 12.5 μm thick photoresist (smearing parameters: 1000 rpm / 30 s). By optimizing the pre-bake process (110 °C / 5 min) to eliminate the solvent gradient, and using OPC (Optical Proximity Correction) to correct the mask, combined with the EVG6200 lithography machine (exposure 46 s, development 9 min), the pattern transfer problem in the thick photoresist process was effectively solved. Step (3) provides a routine mask morphology for subsequent high aspect ratio etching.

[0106] (4) Deep silicon etching is performed on the metal hard mask layer and the SOI substrate along the depth direction through the graphic area.

[0107] As a preferred method, the mask is a genuine one, the graphic area is a non-light-transmitting area, and the etching is performed using dry etching technology, which is divided into three steps: IBE ion beam etching, silicon oxide etching and deep silicon etching.

[0108] As a preferred embodiment, during the entire process, the etching gases are SF6 and C4F8, which play the roles of etching and polymer protection respectively.

[0109] In order to control the sidewall etching angle, the etching process optimized processes such as power, SF6 and C4F8 gas flow rates to achieve a balance between etching rate and sidewall morphology.

[0110] (5) Removing the metal hard mask layer and the photoresist layer.

[0111] As a preferred method, acetone is used to strip the photoresist and Cr etching solution is used to remove the metal mask.

[0112] Finally, a DISCO dicing machine was used to cleave the wafer, and the chip edge cracks were less than 20 μm.

[0113] Since common groove structures are long strips, the etchant diffusion and ion bombardment directions are relatively consistent, making it easy to achieve uniform etching. However, due to the three-dimensional closed nature of deep hole structures, the etching rate decreases gradually from the opening to the bottom, which can easily lead to process defects such as over-etching of the hole mouth and insufficient etching of the bottom. The preparation method of this embodiment adopts the method of setting a metal hard mask layer on the SOI substrate to effectively suppress the problems of hole mouth expansion and uneven depth etching caused by lateral etching, ensuring stable control of structures with extreme dimensions with high aspect ratios. Ensure the structural dimensions of the hole and groove structure are accurate, thereby providing an accurate basis for the subsequent characterization of key dimensions.

[0114] Those skilled in the art will understand that the foregoing descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will be able to modify the technical solutions described in the foregoing embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for characterizing a high aspect ratio micro-hole groove standard template, wherein multiple said standard templates are formed on a single wafer, said standard template is provided with a tracking structure and a micro-hole groove to be sliced, characterized in that: The characterization method comprises the following steps: Set parallel macro marking lines and medium size marking lines. The distance from the edge of the micro-hole slot to be sliced ​​to the macro marking line is l 1. The distance to the middle size mark line is l 2, l 1> l 2; The tracking structure is used to locate the aperture plane of the microporous groove to be sliced, and the aperture edge contour of the microporous groove in the image is extracted. The reference diameter of the microporous groove to be sliced ​​is obtained by binarization processing and least squares circle fitting; Performing a preliminary cutting of the standard template along the macro marking line to preliminarily thin the area between the edge of the microporous slot to be sliced ​​and the edge of the standard template to obtain a single slice; On the primary slice, grinding is performed along the macroscopic marking line until it reaches the medium-sized marking line, thereby obtaining a secondary slice; Using the middle size mark line as the cutting path and the reference diameter as the target diameter, the secondary slice is ground layer by layer to obtain a preparation surface of the microporous groove diameter section to be sliced; Measure and obtain the measured values ​​of the prepared surface, which include the depth, top width, and half-height full width of the microporous groove, where the half-height full width is the width of the microporous groove at half the depth; Based on the measured value and the reference diameter, a spatial geometric deviation model is established to characterize the position deviation between the prepared surface and the ideal surface of the diameter profile. The measured value is error compensated based on the position deviation to convert the measured value into an equivalent value of the ideal surface.

2. The characterization method according to claim 1, characterized in that The performing error compensation on the measured value based on the position deviation includes: Calculate the vertical distance between the prepared surface and the ideal surface of the diameter section d : ; Where, D T The reference diameter 、L T is the measured top width; The measured value of the full width at half maximum L Convert to the equivalent value of the ideal surface D : .

3. The characterization method according to claim 1, characterized in that The micro-hole grooves to be sliced ​​on the standard template at multiple positions of the wafer are characterized to obtain multiple equivalent values ​​and calculate the average value as the final characterization result.

4. The characterization method according to claim 1, characterized in that The nominal size of the microporous groove to be sliced ​​is 10 μm; l 1 = 200 μm to 300 μm; l 2=20 μm±2 μm。 5. The characterization method according to claim 1, characterized in that The preliminary cutting is performed using a DISCO dicing machine; and the grinding is performed using an ultra-precision mechanical grinding process.

6. The characterization method according to claim 5, characterized in that The method of setting mutually parallel macro marking lines and medium-sized marking lines includes: Corresponding cutting parameters are set in the cutting and grinding equipment, or corresponding physical marks are set on the standard template.

7. The characterization method according to claim 1, characterized in that The imaging, layer-by-layer grinding and measurement were performed using a FIB system.

8. A standard sample plate with a high aspect ratio micro-hole groove, characterized in that: The standard sample is prepared by semiconductor technology; The standard sample adopts the characterization method described in any one of claims 1 to 7 to determine the size parameters of the high aspect ratio micro-hole groove.

9. The high aspect ratio micro-hole groove standard template according to claim 8, characterized in that: The standard sample plate is also provided with a calibration micro-hole groove, which has the same structure and size parameters as the micro-hole groove to be sliced.

10. A method for preparing a high aspect ratio micro-hole groove standard template according to claim 8, characterized in that: include: preparing an SOI substrate; Disposing a metal hard mask layer on the SOI substrate; Disposing a photoresist layer on the metal hard mask layer and forming a pattern area by photolithography; Performing deep silicon etching on the metal hard mask layer and the SOI substrate along a depth direction through the pattern area; The metal hard mask layer and the photoresist layer are removed.

Images