Three-dimensional microstructure etching method for analyzing contour evolution based on discrete point iteration

Abstract

The invention discloses a three-dimensional microstructure etching method for analyzing contour evolution based on discrete point iteration. The three-dimensional microstructure etching method comprises the following steps: firstly, plating a mask on the surface of a sample piece to be etched; the method comprises the following steps: establishing a coordinate system according to an expected structure of a to-be-etched sample piece, calculating a unit tangent angle, an actual beam incidence angle and an actual etching factor of each to-be-etched point in a to-be-etched point set of # imgabs0 # at the current moment, and calculating the actual beam incidence angle of each to-be-etched point by taking dt as a time increment, according to the to-be-etched point set at the current moment # imgabs1 #, coordinates of to-be-etched points of the to-be-etched point set at the next moment # imgabs2 # are calculated, and iteration is repeated until the to-be-etched point set at the next moment # imgabs3 # meets an expected value; and then putting the sample piece to be etched into reactive ion beam etching equipment, and sequentially performing reactive ion beam etching processing on each point to be etched according to the actual beam incidence angle and the actual etching factor of each point to be etched. The invention aims to realize three-dimensional microstructure etching based on the reactive ion beam etching process and improve the manufacturing precision of the three-dimensional microstructure.

Description

Technical Field

[0001] The invention relates to the technical field of three-dimensional micro-nano structure etching, and in particular to a three-dimensional microstructure etching method based on discrete point iterative analysis of contour evolution. Background Art

[0002] In recent years, with the rapid development of super-surfaces, MEMS devices, and photonic quantum devices, reactive ion beam etching (RIBE) technology has been widely used in the etching process of three-dimensional micro-nano structures. Traditional micro-nano three-dimensional structures are mostly made using technologies such as focused ion beam (FIB) and electron beam lithography (EBL). Although they can obtain three-dimensional structures with nanometer precision, their movement range is extremely small, only at the micron level, and they cannot be applied at the millimeter level. In the etching process of reactive ion etching (RIE), it is difficult to control the density of free radicals in the discharge chamber, and it is difficult to avoid lateral drilling of the structure, so it is difficult to obtain a high-precision three-dimensional structure. How to apply reactive ion beam etching technology to three-dimensional microstructure etching to obtain high-precision three-dimensional microstructures has become a key technical problem that needs to be solved urgently. Summary of the invention

[0003] Technical problem to be solved by the present invention: In view of the above-mentioned problems in the prior art, a three-dimensional microstructure etching method based on discrete point iterative analysis of contour evolution is provided. The present invention aims to realize three-dimensional microstructure etching based on reactive ion beam etching process and improve the manufacturing accuracy of three-dimensional microstructures.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: A three-dimensional microstructure etching method based on discrete point iterative analysis of profile evolution comprises the following steps: S1, a patterned mask is plated on the surface of the sample to be etched; a coordinate system is established according to the expected structure of the sample to be etched, and a coordinate set of contour points of the expected structure is determined. ,in ~ For the 1st~ The coordinates of the contour points of the desired structure; S2, determine the etching factor and select the ion incident angle , etching factor is the angle between the side wall and the base of the three-dimensional microstructure; S3, according to the ion incident angle Determine the length of the ion irradiation area by the structural parameters of the mask , the length of the ion irradiation zone Divided evenly Discrete etching points ~ , thereby determining the current time The set of points to be etched ; S4, the current time The set of points to be etched Determine the etching boundary control point at the boundary of the etching area; S5, calculate the current time The set of points to be etched The unit tangent angle of each point to be etched; S6, calculate the current time according to the unit tangent angle The actual beam incident angle of each point to be etched; S7, determine the current time according to the actual beam incident angle The actual etching factor of each point to be etched; S8, according to the current time t The coordinates of the points to be etched are d t is the time increment, calculate the next moment The set of points to be etched The coordinates of the n points to be etched ~ ; S9, determine the next moment The set of points to be etched The coordinates of each point to be etched and the coordinate set of the contour points of the desired structure Whether the distance between the corresponding contour point coordinates meets the requirements, if it does, then record the total dwell time of all the points to be etched , jump to step S10; otherwise, the next moment The set of points to be etched As the new present moment The set of points to be etched , jump to step S4; S10, placing the sample to be etched into the reactive ion beam etching equipment, and , total beam accelerating voltage As well as the actual beam incident angle, actual etching factor and total dwell time of each point to be etched , performing reactive ion beam etching processing on each point to be etched in turn; S11, detecting the etching depth of the sample to be etched. If the etching depth of the sample to be etched has not reached the requirement, jump to step S3; otherwise, end and exit.

[0005] Optionally, the calculation function expression of the unit tangent angle in step S5 is: , in, For the current moment No. Points to be etched The unit tangent angle of and The current moment No. Points to be etched The line segment formed by the adjacent points to be etched at a specified distance on both sides Axis angle.

[0006] Optionally, the calculation function expression of the actual beam incident angle in step S6 is: , in, For the current moment No. Points to be etched The actual beam incident angle, is the etching factor according to the desired structure The selected ion incident angle, For the current moment No. Points to be etched The unit tangent angle of .

[0007] Optionally, in step S2, the etching factor is determined and select the ion incident angle When the desired structure is included, the etching factor Substitute the pre-fitted etching factor and ion incident angle into The relationship function is used to obtain the corresponding ion incident angle .

[0008] Optionally, the calculation function expression of the actual etching factor in step S7 is: , in, For the current moment No. Points to be etched The actual etching factor, is the pre-fitted etching factor and ion incident angle The relationship function, For the current moment No. Points to be etched The actual beam incident angle.

[0009] Optionally, in step S8, the next moment is calculated The set of points to be etched middle The coordinates of the points to be etched ~ At any time The calculation function expression of the coordinates of the points to be etched is: , in, For the next moment The set of points to be etched Middle The coordinates of the points to be etched, For the current moment No. The coordinates of the points to be etched, is the pre-fitted etching efficiency and ion incident angle The relationship function, For the current moment No. Points to be etched The actual beam incident angle, For the current moment No. Points to be etched The ion incident angle The unit length vector of For the current moment No. Points to be etched The etching time increment.

[0010] Optionally, it also includes pre-fitting the etching factor and the ion incident angle The relationship function between etching efficiency and ion incident angle The steps of the relationship function are: S101, selecting a plurality of samples of the same material as the sample to be etched and coating a patterned mask on the surface thereof; S102, placing multiple samples on the reactive ion beam etching equipment in step S10 respectively, using the same ion source beam current density as in step S10 , total beam accelerating voltage Perform multiple specified ion incident angles Etching process under the condition of ion incidence angle The etching factor and etching depth of the etching process under the condition of The etching factor of the etching process under the condition of The relationship function for various ion incident angles The etching efficiency of the etching process under the condition of relationship function.

[0011] Optionally, the function expression for calculating the etching efficiency according to the etching depth is: , in, is the etching efficiency, is the etching depth, is the etching processing time of the sample.

[0012] Optionally, when a patterned mask is plated on the surface of the sample to be etched in step S1, the etching ratio of the mask material to the substrate material of the sample to be etched is greater than 1:10, and the width of the mask is satisfy , the height of the mask satisfy , and are the width and height of the three-dimensional microstructure, respectively.

[0013] Optionally, the three-dimensional microstructures are distributed in an array on the substrate of the sample to be etched, and each three-dimensional microstructure is composed of a lower frustum at the bottom and an upper frustum inverted on the top of the lower frustum.

[0014] Compared with the prior art, the present invention can mainly achieve the following beneficial effects: the method of the present invention comprises iteratively determining each current moment The point to be etched ; is the current moment The point to be etched Determine the etching boundary control point at the etching area boundary; calculate the current moment The point to be etched The unit tangent angle, actual beam incident angle, and actual etching factor are calculated based on the current moment. t The point to be etched Calculate the next moment The point to be etched Finally, the sample to be etched is placed in the reactive ion beam etching equipment, and the ion source beam current density is set according to the preset , total beam accelerating voltage As well as the actual beam incident angle and the actual etching factor of each point to be etched, reactive ion beam etching is performed on each point to be etched in turn. The above method realizes the contour evolution based on discrete point iterative analysis, which can realize the three-dimensional microstructure etching based on reactive ion beam etching process, and effectively improve the manufacturing accuracy of the three-dimensional microstructure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the basic flow of the method of the embodiment of the present invention.

[0016] Figure 2 Schematic diagram of the principle of a reactive ion beam etching device in an embodiment of the present invention.

[0017] Figure 3 Schematic diagram of the required structure of the three-dimensional microstructure in an embodiment of the present invention.

[0018] Figure 4 This is an example diagram of the initial surface to be etched in an embodiment of the present invention.

[0019] Figure 5 Schematic diagram of etching point coordinate calculation and iteration in the iterative process in an embodiment of the present invention.

[0020] Figure 6 Graph 1 is the corresponding relationship between the etching efficiency and the ion incident angle in the embodiment of the present invention.

[0021] Figure 7 Graph 1 is the corresponding relationship between the etching factor and the ion incident angle in the embodiment of the present invention.

[0022] Figure 8 This is a schematic diagram of the initial surface to be etched of the sample in an embodiment of the present invention.

[0023] Fig. 9 Schematic diagram of parameter changes during the iterative process of the etched point in an embodiment of the present invention.

[0024] Fig.10 Schematic diagram of iterative results of simulation calculations at various points in an embodiment of the present invention.

[0025] Fig.11 This is a structural diagram after etching for 10 minutes in an embodiment of the present invention.

[0026] Fig.12 This is a structural diagram after etching for 20 minutes in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings in the embodiments of the present invention. Figure 1As shown, the three-dimensional microstructure etching method based on discrete point iterative analysis of profile evolution in this embodiment includes the following steps: S1, a patterned mask is plated on the surface of the sample to be etched; a coordinate system is established according to the expected structure of the sample to be etched, and a coordinate set of contour points of the expected structure is determined. ,in ~ For the 1st~ The coordinates of the contour points of the desired structure; S2, determine the etching factor and select the ion incident angle , etching factor is the angle between the side wall and the base of the three-dimensional microstructure; S3, according to the ion incident angle Determine the length of the ion irradiation area by the structural parameters of the mask , the length of the ion irradiation zone Divided evenly Discrete etching points ~ , thereby determining the current time The set of points to be etched ; S4, the current time The set of points to be etched Determine the etching boundary control point at the boundary of the etching area; S5, calculate the current time The set of points to be etched The unit tangent angle of each point to be etched; S6, calculate the current time according to the unit tangent angle The actual beam incident angle of each point to be etched; S7, determine the current time according to the actual beam incident angle The actual etching factor of each point to be etched; S8, according to the current time t The coordinates of the points to be etched are d t is the time increment, calculate the next moment The set of points to be etched middle The coordinates of the points to be etched ~ ; S9, determine the next moment The set of points to be etched The coordinates of each point to be etched and the coordinate set of the contour points of the desired structure Whether the distance between the corresponding contour point coordinates meets the requirements, if it does, then record the total dwell time of all the points to be etched , jump to step S10; otherwise, the next moment The set of points to be etched As the new present moment The set of points to be etched , jump to step S4; S10, placing the sample to be etched into the reactive ion beam etching equipment, and , total beam accelerating voltage As well as the actual beam incident angle, actual etching factor and total dwell time of each point to be etched , performing reactive ion beam etching processing on each point to be etched in turn; S11, detecting the etching depth of the sample to be etched. If the etching depth of the sample to be etched has not reached the requirement, jump to step S3; otherwise, end and exit.

[0028] like Figure 2 As shown, the reactive ion beam etching device in this embodiment includes: a three-dimensional motion platform 5, a control device 7 and a gas distribution unit 8, a reactive etching ion source 3 is provided on the three-dimensional motion platform 5, an ion source water cooling module 4 is provided on the wide beam ion source 3, and a water cooling fixture 1 that can be tilted and rotated is arranged in the ion source emission direction of the reactive etching ion source 3, and the water cooling fixture 1 is connected to the water cooler 6, and can rotate 180 degrees in the YZ plane and 360 degrees in the XY plane. The gas distribution unit 8 includes a gas mixing tank 9 and multiple groups of gas cylinders 11, and each gas cylinder 11 is connected to the gas mixing tank 9 through a corresponding gas flow control valve 10, the output end of the gas mixing tank 9 is connected to the reactive etching ion source 3, and the water cooler 6, the wide beam ion source 3, the three-dimensional motion platform 5 and the gas flow control valve 10 are all connected to the control device 7. Placing the sample to be etched into the reactive ion beam etching device means installing the sample to be etched on the water-cooling fixture 1. In this embodiment, vacuum thermal conductive silicone grease is applied to the back of the sample to be etched to ensure that it is in good contact with the water-cooling fixture 1, and the water cooler 6 is turned on to ensure that the water cooling cycle is normal, the ion source water cooling module 4 operates normally, and the surface temperature of the sample to be etched does not exceed 30° C. Then, the gas mass flow meter is controlled by the control device 7 to pass the reactive ion beam etching process gas into the reactive etching ion source 3 to discharge the ion source.

[0029] When a patterned mask is plated on the surface of the sample to be etched in step S1, the etching ratio of the mask material to the substrate material of the sample to be etched is greater than 1:10, and the width of the mask is satisfy , the height of the mask satisfy , and are the width and height of the three-dimensional microstructure respectively. Figure 3 As shown, the three-dimensional microstructures in this embodiment are distributed in an array on the substrate of the sample to be etched, and each three-dimensional microstructure is composed of a lower frustum at the bottom and an upper frustum inverted on the top of the lower frustum. This structure is commonly used for metasurface infrared band reflectors and optical phase control. Figure 3 middle, is the top width of the three-dimensional microstructure, is the height of the three-dimensional microstructure, is the structural period of the three-dimensional microstructure, is the etching factor (the angle between the side wall of the three-dimensional microstructure and the processed base surface), is the structural height of the upper cone, is the bottom width of the three-dimensional microstructure. In this embodiment, the substrate material of the sample to be etched is single crystal silicon, and the top width is ， Bottom Width , etching factor , Structural period ， Structural height of upper cone , the height of the three-dimensional microstructure The patterned mask is circular, and the width of the mask is , the height of the mask The material of the mask is chromium, and the etching ratio to the substrate material is 1:12 under the bombardment of the ion beam formed by SF6 gas.

[0030] In step S2 of this embodiment, the etching factor is determined and select the ion incident angle When the desired structure is included, the etching factor Substitute the pre-fitted etching factor and ion incident angle into The relationship function is used to obtain the corresponding ion incident angle ,Right now: ,in is the pre-fitted etching factor and ion incident angle For example, in this embodiment, according to the etching factor of the desired structure Select the initial ion incident angle is 70°.

[0031] In step S3 of this embodiment, according to the ion incident angle Determine the length of the ion irradiation area by the structural parameters of the mask , the length of the ion irradiation zone Divided evenly discrete points to be etched ( ), thereby determining the current time The point to be etched , the initial moment , its coordinates can be determined according to the coordinate system; Figure 4 This is an example of the initial surface to be etched in this embodiment. The points to be etched are all ion irradiation area length The discrete points within are specifically divided into 10nm intervals.

[0032] In step S4 of this embodiment, the current time The point to be etched The etching boundary control point is determined at the etching area boundary, and 100 nm Determine the boundary point and Since the ion beam irradiation energy at these two points is basically zero, the two etching boundary control points and are all regarded as fixed points, such as Figure 4 In this embodiment, two etching boundary control points are specifically determined. and The coordinates are: and .

[0033] The calculation function expression of the unit tangent angle in step S5 of this embodiment is: , in, For the current moment No. Points to be etched The unit tangent angle of and The current moment No. Points to be etched The line segment formed by the adjacent points to be etched at a specified distance on both sides Axis angle.

[0034] The calculation function expression of the actual beam incident angle in step S6 of this embodiment is: , in, For the current moment No. Points to be etched The actual beam incident angle, is the etching factor according to the desired structure The selected ion incident angle, For the current moment No. Points to be etched The unit tangent angle of .

[0035] The calculation function expression of the actual etching factor in step S7 of this embodiment is: , in, For the current moment No. Points to be etched The actual etching factor, is the pre-fitted etching factor and ion incident angle The relationship function, For the current moment No. Points to be etched The actual beam incident angle.

[0036] In step S8 of this embodiment, the next moment is calculated The set of points to be etched middle The coordinates of the points to be etched ~ At any time The calculation function expression of the coordinates of the points to be etched is: , in, For the next moment The set of points to be etched Middle The coordinates of the points to be etched, For the current moment No. The coordinates of the points to be etched, is the pre-fitted etching efficiency and ion incident angle The relationship function, For the current moment No. Points to be etched The actual beam incident angle, For the current moment No. Points to be etched The ion incident angle The unit length vector of For the current moment No. Points to be etched The etching time increment.

[0037] In step S9 of this embodiment, the next moment is determined The set of points to be etched The coordinates of each point to be etched and the coordinate set of the contour points of the desired structure Whether the distance between the corresponding contour point coordinates meets the requirements, if it does, then record the total dwell time of all the points to be etched , jump to step S10; otherwise, the next moment The set of points to be etched As the new present moment The set of points to be etched , jump to step S4. It should be noted that the time for each point to be etched is the time increment , so the total residence time of all the points to be etched is counted The method is: ,and Initially it is 0. As an optional implementation, in this embodiment, the time increment 0.01min (for easy observation, Figure 4 Only data points with an integer etching time t are shown in the figure. The total residence time For 20 minutes.

[0038] In addition, this embodiment also includes pre-fitting the etching factor and the ion incident angle The relationship function between etching efficiency and ion incident angle The steps of the relationship function are: S101, selecting a plurality of samples of the same material as the sample to be etched and coating a patterned mask on the surface thereof; S102, placing multiple samples on the reactive ion beam etching equipment in step S10 respectively, using the same ion source beam current density as in step S10 , total beam accelerating voltage Perform multiple specified ion incident angles Etching process under the condition of ion incidence angle The etching factor and etching depth of the etching process under the condition of The etching factor of the etching process under the condition of The relationship function of Figure 7 As shown, for various ion incident angles The etching efficiency of the etching process under the condition of The relationship function of Figure 6As shown. Among them, the depth detection equipment can be selected according to the needs, such as white light interferometer, atomic force microscope (AFM, Atomic Force Microscope), scanning electron microscope (SEM, Scanning Electron Microscope), profilometer, confocal microscope, etc. In this embodiment, the depth detection equipment is used to detect various ion incident angles The etching factor and etching depth of the etching process at 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° are shown in Table 1. The dwell time is t= 5min. The etching depth at 9 angles in step S5 and the etching factor (i.e. the angle between the side wall and the initial base surface) were detected by SEM (scanning electron microscope). . Using a cubic polynomial to fit the ion incident angle (i.e., the ion beam direction and x Axis positive angle) corresponding relationship ， Get the etching efficiency and ion incident angle The relationship function is as follows Figure 6 As shown, the etching factor and ion incident angle are obtained. The relationship function is as follows Figure 7 As shown, the function expressions are: , , in, is the etching factor, is the etching efficiency; is the independent variable, i.e., the ion incident angle .

[0039] In this embodiment, the function expression for calculating the etching efficiency according to the etching depth is: , in, is the etching efficiency, is the etching depth, such as Figure 5 As shown, is the etching processing time of the sample.

[0040] In this embodiment, the sample is etched from top to bottom through the previous process, and after the etching is completed, it serves as the initial structure in the method of this embodiment, such as Figure 8 In step S10 of this embodiment, the sample to be etched is placed in a reactive ion beam etching device, and the ion source beam current density is preset. , total beam accelerating voltage As well as the actual beam incident angle and actual etching factor of each point to be etched, when each point to be etched is subjected to reactive ion beam etching in turn, the process gas ratio of the material to be etched is selected to be pure SF6, and the ion source beam density is 7mA / cm 2 , total beam accelerating voltage 500V (screen grid DC regulated power supply voltage V s =450V, DC regulated power supply voltage for acceleration gate V c =50V).

[0041] Fig. 9 Schematic diagram of parameter changes during the iterative process of the points to be etched in this embodiment, wherein black circles represent the points to be etched, that is, the black circle points are the initial points to be etched, one iteration is represented by a black triangle, and another iteration is represented by a black square. Fig.10 This is a schematic diagram of the iterative results of each point in the simulation calculation in this embodiment. For ease of observation, only the etching time is shown in the figure. t The data points are integers (5 min, 10 min, 15 min, and 20 min).

[0042] Since the result requires a bilaterally symmetrical structure, the above process is a single-sided etching. After solid processing, the sample is rotated to a symmetrical position and processed at the same beam angle. J 0, total beam accelerating voltage V t Beam Angle ɑ Total dwell time T t The sample is etched. Since the result requires a bilaterally symmetrical structure, the above process is a single-sided etching. After the solid processing, the sample is rotated to a symmetrical orientation and processed at the same beam angle. Fig.11 This is the structural diagram after etching for 10 minutes in this embodiment. Fig.12 This is a structural diagram after etching for 20 minutes in this embodiment.

[0043] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A three-dimensional microstructure etching method based on discrete point iterative analysis of profile evolution, characterized in that The steps include: S1, a patterned mask is plated on the surface of the sample to be etched; a coordinate system is established according to the expected structure of the sample to be etched, and a coordinate set of contour points of the expected structure is determined. ,in ~ For the 1st~ Coordinates of contour points of the desired structure; S2, determine the etching factor and select the ion incident angle , etching factor is the angle between the side wall and the base of the three-dimensional microstructure; S3, according to the ion incident angle Determine the length of the ion irradiation area by the structural parameters of the mask , the length of the ion irradiation zone Divided evenly Discrete etching points ~ , thereby determining the current time The set of points to be etched ; S4, the current time The set of points to be etched Determine the etching boundary control point at the etching area boundary; S5, calculate the current time The set of points to be etched The unit tangent angle of each point to be etched; S6, calculate the current time according to the unit tangent angle The actual beam incident angle of each point to be etched; S7, determine the current time according to the actual beam incident angle The actual etching factor of each point to be etched; S8, according to the current time t The coordinates of the points to be etched are d t is the time increment, calculate the next moment The set of points to be etched middle The coordinates of the points to be etched ~ ; S9, determine the next moment The set of points to be etched The coordinates of each point to be etched and the coordinate set of the contour points of the desired structure Whether the distance between the corresponding contour point coordinates meets the requirements, if it does, then record the total dwell time of all the points to be etched , jump to step S10; Otherwise, the next moment The set of points to be etched As the new present moment The set of points to be etched , jump to step S4; S10, placing the sample to be etched into the reactive ion beam etching equipment, and , total beam accelerating voltage As well as the actual beam incident angle, actual etching factor and total dwell time of each point to be etched , performing reactive ion beam etching processing on each point to be etched in turn; S11, detecting the etching depth of the sample to be etched. If the etching depth of the sample to be etched has not reached the requirement, jump to step S3; otherwise, end and exit.

2. The three-dimensional microstructure etching method based on discrete point iterative analysis of profile evolution according to claim 1, characterized in that: The calculation function expression of the unit tangent angle in step S5 is: ， in, For the current moment No. Points to be etched The unit tangent angle of and The current moment No. Points to be etched The line segment formed by the adjacent points to be etched at a specified distance on both sides Axis angle.

3. The three-dimensional microstructure etching method based on discrete point iterative analysis of profile evolution according to claim 1, characterized in that: The calculation function expression of the actual beam incident angle in step S6 is: ， in, For the current moment No. Points to be etched The actual beam incident angle, is the etching factor according to the desired structure The selected ion incident angle, For the current moment No. Points to be etched The unit tangent angle of .

4. The three-dimensional microstructure etching method based on discrete point iterative analysis of contour evolution according to claim 1, characterized in that: In step S2, the etching factor is determined and select the ion incident angle When the desired structure is included, the etching factor Substitute the pre-fitted etching factor and ion incident angle into The relationship function is used to obtain the corresponding ion incident angle .

5. The three-dimensional microstructure etching method based on discrete point iterative analysis of profile evolution according to claim 4, characterized in that: The calculation function expression of the actual etching factor in step S7 is: ， in, For the current moment No. Points to be etched The actual etching factor, is the pre-fitted etching factor and ion incident angle The relationship function, For the current moment No. Points to be etched The actual beam incident angle.

6. The three-dimensional microstructure etching method based on discrete point iterative analysis of profile evolution according to claim 5, characterized in that: In step S8, the next time is calculated The set of points to be etched middle The coordinates of the points to be etched ~ At any time The calculation function expression of the coordinates of the points to be etched is: ， in, For the next moment The set of points to be etched Middle The coordinates of the points to be etched, For the current moment No. The coordinates of the points to be etched, is the pre-fitted etching efficiency and ion incident angle The relationship function, For the current moment No. Points to be etched The actual beam incident angle, For the current moment No. Points to be etched The ion incident angle The unit length vector of For the current moment No. Points to be etched The etching time increment.

7. The three-dimensional microstructure etching method based on discrete point iterative analysis of profile evolution according to claim 6, characterized in that: Also includes pre-fitting of etch factor and ion incident angle The relationship function between etching efficiency and ion incident angle The steps of the relationship function are: S101, selecting a plurality of samples of the same material as the sample to be etched and coating a patterned mask on the surface thereof; S102, placing multiple samples on the reactive ion beam etching equipment in step S10 respectively, using the same ion source beam current density as in step S10 , total beam accelerating voltage Perform multiple specified ion incident angles Etching process under the condition of ion incidence angle The etching factor and etching depth of the etching process under the condition of The etching factor of the etching process under the condition of The relationship function for various ion incident angles The etching efficiency of the etching process under the condition of relationship function.

8. The three-dimensional microstructure etching method based on discrete point iterative analysis of profile evolution according to claim 7, characterized in that: The functional expression for calculating the etching efficiency according to the etching depth is: ， in, is the etching efficiency, is the etching depth, is the etching processing time of the sample.

9. The three-dimensional microstructure etching method based on discrete point iterative analysis of contour evolution according to claim 1, characterized in that: In step S1, when a patterned mask is plated on the surface of the sample to be etched, the etching ratio of the mask material to the substrate material of the sample to be etched is greater than 1:10, and the width of the mask is satisfy , the height of the mask satisfy , and are the width and height of the three-dimensional microstructure, respectively.

10. The three-dimensional microstructure etching method based on discrete point iterative analysis of profile evolution according to claim 9, characterized in that: The three-dimensional microstructures are distributed in an array on the substrate of the sample to be etched, and each three-dimensional microstructure is composed of a lower frustum at the bottom and an upper frustum inverted on the top of the lower frustum.

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