Method for improving topography of high aspect ratio etching structure, etching equipment and semiconductor structure

Abstract

The present application discloses a method for improving the morphology of a high aspect ratio etching structure, an etching apparatus, and a semiconductor structure. The method includes: forming a plasma with a continuously increasing density in a first space; allowing the plasma, under the natural action of pressure, to be dispersed through the bottom of the first space and diffuse downward into a second space, so that when reaching the surface of a substrate located in the second space, the plasma with a uniform density tends to be formed on the entire surface of the substrate; etching the surface of the substrate downward through the plasma to form a plurality of high aspect ratio etching structures distributed on the substrate, and during the etching process, according to the data of the inclination occurrence region and the inclination degree of the high aspect ratio etching structure obtained, applying an additional local correction electric field to a target improvement region on the substrate, and adjusting the electric field intensity of the local correction electric field to a preset value. The present application can effectively solve the abnormal morphology of etching inclination, and ensure the electrical performance and mechanical reliability of the device.

Description

Technical Field

[0001] The present application relates to the field of semiconductor processing technology, and particularly to a method for improving the topography of a high aspect ratio etching structure, an etching apparatus, and a semiconductor structure. Background Art

[0002] With the continuous improvement of packaging density, the through-silicon via (TSV) process has been commonly used in advanced packaging technologies to achieve interlayer interconnection in three-dimensional integrated circuits. Moreover, with the continuous increase in wafer size, higher requirements are imposed on the etching uniformity of TSVs with a high aspect ratio.

[0003] Trench tilt refers to an etching topography defect in which, during the etching process, the etching deviates from the vertical direction, causing the sidewalls on both sides of the formed TSV to tilt towards the same side direction. This defect will affect the electrical performance and mechanical reliability of the TSV. Therefore, it is necessary to study a process method that can improve the trench tilt defect. Summary of the Invention

[0004] The purpose of the present application is to overcome the above problems existing in the prior art, and provide a method for improving the topography of a high aspect ratio etching structure, an etching apparatus, and a semiconductor structure, so as to improve the trench tilt defect.

[0005] To achieve the above purpose, the technical solution of the present application is as follows:

[0006] According to the first aspect of the present application, an embodiment of the present application provides a method for improving the topography of a high aspect ratio etching structure, including:

[0007] Forming a plasma with a continuously increasing density in a first space;

[0008] Making the plasma, under the natural action of pressure, be dispersed through the bottom of the first space and diffuse downward into a second space, so that when reaching the surface of a substrate located in the second space, the plasma with a uniform density is formed on the entire surface of the substrate;

[0009] Etching the surface of the substrate downward through the plasma to form a plurality of high aspect ratio etching structures distributed on the substrate, and during the etching process, according to the data of the tilt occurrence area and tilt degree of the high aspect ratio etching structure obtained, applying an additional local correction electric field to a target improvement area on the substrate, and adjusting the electric field strength of the local correction electric field to a preset value.

[0010] In some embodiments, along the direction from the center to the edge of the substrate, the plasma is vertically dispersed into multiple plasma gas flows from sparse to dense at the bottom of the first space and diffuses downward into the second space.

[0011] In some embodiments, along the direction from the center to the edge of the substrate, the plasma is vertically dispersed at the bottom of the first space into multiple plasma gas flows with diameters increasing from small to large, and diffuses downward into the second space.

[0012] In some embodiments, a central region and an edge region surrounding the central region are defined on the surface of the substrate. The target improvement region is located in the edge region, the local correction electric field is applied to the edge region, and multiple application regions of the local correction electric field are arranged around the central region.

[0013] In some embodiments, by applying an alternating voltage, the local correction electric field is generated. The magnitude of the power required to be applied to the local correction electric field when reaching the preset value is 1% - 5% of the bias power applied to the entire substrate, and the magnitude of the preset value is proportional to the magnitude of the inclination.

[0014] In some embodiments, the number of application regions of the local correction electric field is 4 - 16 and is evenly distributed.

[0015] In some embodiments, the etching is performed based on the improved Bosch process, and the improved Bosch process is a pulsed plasma etching process using helium protection.

[0016] In some embodiments, during etching, the temperature is 10°C - 60°C, the pressure is 1 mtorr - 100 mtorr, the source power is 100 W - 2000 W, and the bias power is 10 W - 500 W.

[0017] According to the second aspect of the present application, an etching apparatus provided by an embodiment of the present application further includes:

[0018] A cavity, a base is provided on the bottom inside the cavity, and the substrate is to be disposed on the base;

[0019] A gas storage module, disposed in the cavity. The gas storage module has a first space located above the base, a second space is below the first space, and the base is accommodated in the second space. The gas storage module is used to form a plasma with continuously increasing density in the first space, and under the natural action of pressure, the plasma is dispersed and diffused downward through the bottom of the first space into the second space, so that when reaching the surface of the substrate disposed on the base, a plasma with a uniform density tends to be formed on the entire surface of the substrate, and then the surface of the substrate is etched downward through the plasma to form a plurality of high aspect ratio etching structures distributed on the substrate;

[0020] The local correction electric field generation module is disposed on the base, and is used to apply the generated additional local correction electric field to the target improvement area on the substrate during the etching process according to the obtained data of the tilt occurrence area and tilt degree of the high aspect ratio etching structure, and adjust the electric field strength of the local correction electric field to a preset value.

[0021] In some embodiments, the gas storage module includes an air flow dispersion plate which is horizontally disposed above the base, and the side surface of the air flow dispersion plate is in close contact with the side wall of the cavity. The first space and the second space are respectively formed in the cavity on the upper and lower sides of the air flow dispersion plate. A plurality of nano pores are provided on the surface of the air flow dispersion plate, and the nano pores are perpendicular to the surface of the substrate disposed horizontally. The nano pores are used to pass the plasma. The arrangement form of each nano pore is: along the direction from the center of the substrate to the edge, each nano pore is distributed from sparse to dense.

[0022] In some embodiments, the arrangement form of each nano pore is: along the direction from the center of the substrate to the edge, the pore diameter of each nano pore is distributed from small to large.

[0023] In some embodiments, the local correction electric field generation module includes a plurality of independently arranged first electrodes. The surface of the substrate includes a central area and an edge area surrounding the outside of the central area. The target improvement area is located in the edge area. The arrangement positions of the first electrodes on the base are located on the edge area and are evenly arranged around the central area. By applying an alternating voltage to the first electrode corresponding to the position of the target improvement area, the local correction electric field is generated.

[0024] In some embodiments, the etching equipment is used to perform a pulsed plasma etching process protected by helium.

[0025] In some embodiments, the air flow dispersion plate is made of an insulating material.

[0026] In some embodiments, an air inlet part is provided on the top in the cavity, and the air inlet part is communicated with the top of the first space. The air inlet part is used to introduce a process gas into the first space to form the plasma. The first distance between the air inlet part and the surface of the substrate during setting is 100 mm to 200 mm, and the second distance between the air flow dispersion plate and the surface of the substrate during setting is 20 mm to 60 mm.

[0027] In some embodiments, the pore occupancy rate of the nano pores on the air flow dispersion plate gradually increases between 10% and 50% along the direction from the center of the substrate to the edge.

[0028] In some embodiments, the pore diameter of the nano-pores gradually increases and varies between 1 nm and 100 nm along the direction from the center to the edge of the substrate.

[0029] In some embodiments, a second electrode is further provided on the base for applying a bias power to the entire substrate. The magnitude of the power required to be applied to the first electrode when reaching the preset value is 1% - 5% of the applied bias power, and the magnitude of the preset value is proportional to the magnitude of the inclination.

[0030] In some embodiments, the number of the first electrodes is 4 to 16.

[0031] According to the third aspect of the present application, an embodiment of the present application further provides a semiconductor structure, including a substrate and a plurality of high aspect ratio etching structures distributed on the substrate. The high aspect ratio etching structures are fabricated using the high aspect ratio etching structure topography improvement method provided by any one of the embodiments of the first aspect above. Alternatively, the high aspect ratio etching structures are fabricated using the etching equipment provided by any one of the embodiments of the second aspect above.

[0032] The embodiments of the present application can / at least have the following advantages:

[0033] (1) By utilizing the pressure effect, the formed plasma is pressurized and stored in the first space first, so that the density of the plasma continuously increases. Then, under the natural action of the pressure, the plasma is dispersed through the bottom of the first space and diffused downward into the second space, so as to form a plasma with a uniform density on the entire surface of the substrate, realizing the uniform distribution of the process gas (plasma) on the entire surface of the substrate. During the etching process of the high aspect ratio etching structure, according to the obtained data of the inclination occurrence area and the inclination magnitude of the high aspect ratio etching structure, by applying an additional local correction electric field to the target improvement area on the substrate and adjusting the electric field strength of the local correction electric field to the preset value, an electrostatic field with adjustable area and adjustable intensity is constructed to strengthen the anisotropic etching, thereby optimizing the gas field and the local electric field during the etching process of the high aspect ratio etching structure, and effectively solving the abnormal topography of etching inclination generated in the middle to the edge of the substrate and different areas at the edge due to the uneven distribution of the gas field and the electromagnetic field in the past.

[0034] (2) By making the process gas uniformly distributed on the entire surface of the substrate and constructing an electrostatic field with adjustable area and adjustable intensity, a higher etching rate and a stronger anisotropic effect can be exerted, which is beneficial to high aspect ratio etching and improves the process window.

[0035] (3) By effectively improving the abnormal morphology of the etching tilt generated on the substrate, the electrical performance and mechanical reliability of the device are ensured, thereby improving the yield and stability of the device.

[0036] Other advantages of the present application will be elaborated in the following specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of a trench structure that generates an abnormal morphology of etching tilt at the edge of the substrate.

[0038] Figure 2 It is a schematic diagram when blowing process gas using an existing etching device.

[0039] Figure 3 It is a flowchart of a method for improving the morphology of a high aspect ratio etching structure provided by a preferred embodiment of the present application.

[0040] Figure 4 It is a schematic structural diagram of an etching device provided by a preferred embodiment of the present application.

[0041] Figure 5 It is a schematic plane distribution structure diagram of a first electrode provided by a preferred embodiment of the present application.

[0042] Figure 6 For using Figure 4 The schematic diagram when blowing process gas with the etching device.

[0043] Figure 7 It is a scanning electron microscope schematic diagram of the inclined morphology of a trench provided by the comparative example.

[0044] Figure 8 It is a scanning electron microscope schematic diagram of the vertical morphology of the trench obtained after improving the inclined morphology of the trench.

[0045] In the figure, 10. Chamber; 11. Base; 12. Intake part; 13. Exhaust part; 100. Substrate; 101. Trench; 201. First space; 202. Second space; 2011. Bottom of the first space; 22. Gas storage module; 221. Airflow dispersion plate; 222. Nanopores; 24. Local correction electric field generation module; 241. First electrode; A. Central region; B. Edge region. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] During the etching process of through - silicon vias (TSVs) with high aspect ratios, due to the local non - uniformity of the electromagnetic field / plasma distribution, the etching deviates from the vertical direction, resulting in an etched topography defect of trench tilting. This defect can affect the electrical performance and mechanical reliability of the through - silicon vias. However, when improving the etched topography defect of trench tilting, there are still the following technical difficulties:

[0047] (1) Since etching is a reaction kinetic behavior, traditional off - line monitoring means (such as SEM) are difficult to monitor the reaction process in the cavity in real - time and optimize the process parameters at any time.

[0048] (2) During deep - hole etching (such as an aspect ratio greater than 20:1), it is difficult to maintain the uniformity of the plasma density and ion energy distribution, resulting in significant differences in the etching rate in different regions and between the top and bottom of the same region, leading to the trench tilting topography.

[0049] (3) When using the traditional Bosch process for trench etching, vertical etching is achieved by alternately performing etching and passivation cycles. However, small deviations in the cycle switching time, gas ratio, and power parameters are likely to form non - uniformity in local etching and passivation, resulting in the etching deviating from the vertical direction.

[0050] (4) The density of the plasma generated by the radio - frequency coil decreases at the edge of the wafer substrate, resulting in differences in the plasma density on the wafer surface.

[0051] Reference Figure 1 , which shows a plurality of trenches 101 (through - silicon vias) distributed on a substrate 100 (silicon wafer) fabricated by a traditional etching process (such as the Bosch process). The surface of the substrate 100 includes a central region A and an edge region B. The above - mentioned trench tilting defect usually occurs in the edge region B. For example, Figure 1 schematically shows the abnormal morphology of 2 tilted trenches 101 (the bottom of the trench tilts towards the outside of the substrate 100) located in the edge region B, and schematically shows the normal morphology of 4 vertical trenches 101 located in the central region A.

[0052] Figure 7 shows the actual topography when a trench is tilted ( Figure 7 In it, mark 1 indicates a depth of 1.3908 microns in the Y - direction, mark 2 indicates a top width of 1.9807 microns in the X - direction, and mark 3 indicates a bottom width of 1.9807 microns in the X - direction), and the trench tilt angle is about 2 degrees.

[0053] Reference Figure 2, which shows the uneven distribution effect of process gas on the surface of the substrate 100 when using an existing blowing method. An existing inductively coupled plasma (ICP) etching device includes a cavity 10, an air inlet part 12 (such as a jet nozzle) is provided on the top inside the cavity 10, a pedestal 11 (such as an electrostatic chuck) for setting the substrate 100 (such as a wafer) is provided on the bottom inside the cavity 10, and an exhaust part 13 (such as an exhaust port) for exhausting. The air inlet part 12 is used to input the process gas for etching into the cavity 10. Through the radio frequency coil provided on the cavity 10, the process gas is excited to form plasma, and under the action of the bias power, it is introduced downward to the surface of the placed substrate 100 for etching. Since the area of the air inlet part 12 is much smaller than the area of the substrate 100, it is easy to cause an uneven distribution phenomenon where the plasma density is high in the middle and low at the edges, resulting in a difference in the plasma density on the surface of the substrate 100. Moreover, the actual electromagnetic field intensity acting on the edge region B is often less than that in the central region A. The above factors lead to the frequent occurrence of trench tilt in the edge region B.

[0054] To solve the above problems existing in the prior art, the embodiments of the present application provide a method for improving the topography of high aspect ratio etching structures, an etching device, and a semiconductor structure to improve trench tilt defects.

[0055] The following will describe the specific embodiments of the present application in detail with reference to the accompanying drawings.

[0056] Reference Figure 3 . The embodiments of the present application provide a method for improving the topography of high aspect ratio etching structures, including:

[0057] Forming plasma with a continuously increasing density in the first space;

[0058] Making the plasma disperse and diffuse downward through the bottom of the first space under the natural action of pressure into the second space, so that when reaching the surface of the substrate located in the second space, plasma with a uniform density is formed on the entire surface of the substrate;

[0059] Etching the surface of the substrate downward through the plasma to form a plurality of high aspect ratio etching structures distributed on the substrate, and during the etching process, according to the obtained data of the tilt occurrence area and tilt degree of the high aspect ratio etching structures, applying an additional local correction electric field to the target improvement area on the substrate, and adjusting the electric field intensity of the local correction electric field to a preset value.

[0060] A method for improving the topography of a high aspect ratio etching structure provided in the above embodiments of the present application, by utilizing the pressure effect, first pressurizes and stores the formed plasma in the first space, so that the density of the plasma continuously increases, and then under the natural action of the pressure, the plasma is dispersed through the bottom of the first space and diffused downward into the second space, so as to form a plasma with a uniform density on the entire surface of the substrate, realizing the uniform distribution of the process gas (plasma) on the entire surface of the substrate, and during the etching process of the high aspect ratio etching structure, according to the measurement of the inclination of the high aspect ratio etching structure on the previous substrate that has completed the etching process of the high aspect ratio etching structure, and the data of the inclination occurrence area and the inclination magnitude of the pre-acquired high aspect ratio etching structure, by applying an additional local correction electric field to the target improvement area (i.e., the inclination occurrence area on the previous substrate) on the current substrate, and adjusting the electric field strength of the local correction electric field to a preset value, constructing an electrostatic field with adjustable region and adjustable intensity, so as to enhance the physical bombardment effect and strengthen the anisotropic etching, thereby optimizing the gas field and the local electric field during the etching process of the high aspect ratio etching structure, effectively solving the abnormal topography of etching inclination generated in the middle to the edge of the substrate and different regions of the edge due to the uneven distribution of the gas field and the electromagnetic field in the past.

[0061] In some embodiments, the high aspect ratio etching structure includes trenches (deep trenches), deep vias (Deep Via), or through vias (Through Via) with an aspect ratio of 20:1 or more. Hereinafter, taking the high aspect ratio etching structure as a trench with an aspect ratio of 20:1 or more as an example, the embodiments of the present application will be described in detail.

[0062] Reference Figure 4 And Figure 6 In some embodiments, a chamber 10 for performing an etching process can be utilized, and a first space 201 and a second space 202 are formed in the chamber 10. Among them, the first space 201 and the second space 202 are arranged up and down, and the first space 201 and the second space 202 are communicably isolated through the bottom 2011 of the first space. The first space 201 and the second space 202 are relatively closed environments. The substrate 100 (such as a wafer) is arranged in the second space 202.

[0063] In some embodiments, a plurality of tiny hollow parts can be arranged on the bottom 2011 of the first space.

[0064] In some embodiments, the hollow part can be a pore.

[0065] In some embodiments, the size of the pores can be nanoscale, such that when continuously ventilating (process gas) into the first space 201, a certain obstructive effect on the gas flow is generated by the nanoscale pores (nano-pores 222), so that the gas outlet volume when passing through the bottom 2011 of the first space is less than the gas inlet volume when ventilating into the first space 201, achieving the effect of storing gas under a certain air pressure in the first space 201 above the bottom 2011 of the first space, until the air pressure in the first space 201 increases to a state where the inlet volume and the outlet volume reach a dynamic equilibrium, realizing the purpose of stably transporting the gas stored in the first space 201 into the second space 202.

[0066] In some embodiments, the boundary of the orthographic projection in the vertical direction of all the pores on the bottom 2011 of the first space completely covers at least the surface of the substrate 100 horizontally arranged in the second space 202.

[0067] In some embodiments, the plasma is formed by exciting the etching process gas. By continuously introducing the process gas into the first space 201, continuous pressurized gas storage of the process gas in the first space 201 is achieved (i.e., the density of the process gas continuously increases), and the process gas is relatively evenly distributed in the relatively enclosed first space 201 during this process, so that the density of the process gas at each position in the first space 201 is relatively consistent. By exciting the process gas after entering the first space 201 in the first space 201, a plasma is formed, and the density of the formed plasma also increases as the density of the process gas continuously increases until the critical state. In this way, a plasma in a uniform state with relatively consistent density at each position can be formed in the relatively enclosed first space 201 through the action of pressure.

[0068] In some embodiments, the substrate 100 is horizontally arranged in the second space 202. When the air pressure in the first space 201 reaches a certain level (the state where the inlet volume and the outlet volume reach a dynamic equilibrium, the critical state), the plasma formed in the first space 201 will, under the natural action of pressure, be dispersed and diffused downward through the nano-pores 222 on the bottom 2011 of the first space into the second space 202. Among them, along the direction from the center to the edge of the substrate 100, the plasma is vertically dispersed into multiple plasma gas flows from sparse to dense at the bottom 2011 of the first space and diffused downward into the second space 202.

[0069] In some embodiments, when the substrate 100 is horizontally disposed in the second space 202, the center of the bottom 2011 of the first space is aligned (or substantially aligned) with the center of the substrate 100. Along the direction from the center of the bottom 2011 of the first space towards the edge, by distributing the nano pores 222 from sparse to dense on the bottom 2011 of the first space, the plasma is vertically dispersed by the nano pores 222 on the bottom 2011 of the first space into multiple plasma gas flows from sparse to dense, and diffuses downward towards the surface of the substrate 100.

[0070] In some embodiments, at each position on the bottom 2011 of the first space, the pore diameters of the nano pores 222 are the same. In this case, the number of nano pores 222 gradually increases along the direction from the center of the bottom 2011 of the first space towards the edge (along the direction from the center of the substrate 100 towards the edge). That is, along the direction from the center of the bottom 2011 of the first space towards the edge, the pore occupancy rate of the nano pores 222 (the area ratio of the nano pores 222 in the unit area on the bottom 2011 of the first space) gradually increases.

[0071] In some embodiments, along the direction from the center of the bottom 2011 of the first space towards the edge (along the direction from the center of the substrate 100 towards the edge), the plasma is vertically dispersed on the bottom 2011 of the first space into multiple plasma gas flows with diameters increasing from small to large, and diffuses downward into the second space 202.

[0072] In some embodiments, along the direction from the center of the bottom 2011 of the first space towards the edge (along the direction from the center of the substrate 100 towards the edge), by gradually increasing the pore diameters of the nano pores 222, the plasma is vertically dispersed by the nano pores 222 on the bottom 2011 of the first space into multiple plasma gas flows with diameters increasing from small to large, and diffuses downward into the second space 202. In this case, the number of nano pores 222 gradually increases along the direction from the center of the bottom 2011 of the first space towards the edge. Or, along the direction from the center of the bottom 2011 of the first space towards the edge, the pore occupancy rate (opening rate) of the nano pores 222 gradually increases.

[0073] It should be noted that the densities of the multiple plasma gas flows output from the nano pores 222 at the bottom 2011 of the first space are the same (or substantially the same). However, since the pore occupancy rate formed by the nano pores 222 along the direction from the center of the bottom 2011 of the first space towards the edge gradually increases, when the plasma just outputs from the nano pores 222 at the bottom 2011 of the first space, the gas output amount along the direction from the center of the bottom 2011 of the first space towards the edge gradually increases, showing a state where the gas amount at the center is less and the gas amount at the edge is more, as Figure 6As shown by the solid arrow pointing downward in [FIGURE]. After that, when the output plasma gradually moves downward and away from the bottom 2011 of the first space, it will be continuously affected by the negative pressure of the chamber bottom exhaust. As a result, the gas flow at the edge will be attracted and flow more outward compared to the gas flow at the center. Therefore, when the plasma finally contacts the surface of the substrate 100, the amount of gas flow reaching the edge can be made to be consistent with the amount of gas flow reaching the center, and the density of the gas flow from the center to the edge of the substrate 100 surface can also be made consistent, as Figure 6 shown by the hollow arrow pointing downward in [FIGURE]. Thus, when the plasma contacts the surface of the substrate 100, a uniform distribution on the surface of the substrate 100 is achieved, thereby improving the process uniformity.

[0074] In some embodiments, a central region A and an edge region B surrounding the outside of the central region A are defined on the surface of the substrate 100. Among them, according to the characteristic that the inclined occurrence region of the high aspect ratio etching structure is usually located in the edge region B (determined according to actual detection), the target improvement region is determined to be located in the edge region B, and a local correction electric field is applied to the edge region B. And, a plurality of application regions of the local correction electric field are arranged around the central region A.

[0075] In some embodiments, an alternating voltage is applied to the application region of the local correction electric field to generate a local correction electric field.

[0076] In some embodiments, the magnitude of the power required to be applied to the local correction electric field when reaching the above preset value is 1% to 5% of the bias power conventionally applied to the entire substrate 100. That is, the magnitude of the power required to be applied to the local correction electric field is adjusted with reference to the bias power. For example, the magnitude of the power required to be applied to the local correction electric field when reaching the above preset value can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% of the bias power conventionally applied to the entire substrate 100, etc., but is not limited thereto.

[0077] Moreover, the magnitude of the preset value is proportional to the magnitude of the trench inclination. That is, when the trench inclination is larger, the electric field strength that needs to be applied should also be larger, and the preset value is higher. Therefore, the power applied to the local correction electric field also needs to be increased correspondingly.

[0078] In some embodiments, the number of application regions of the local correction electric field is 4 to 16 uniformly distributed around the central region A. For example, the number of application regions of the local correction electric field can be 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16.

[0079] It should be noted that due to the existence of trench inclination, deep silicon etching easily causes lateral etching, which in turn affects the etching in the depth direction. In the embodiments of the present application, by first making the process gas uniformly distributed on the entire surface of the substrate 100, and then constructing an electrostatic field with adjustable region and intensity, a better etching in the depth direction can be achieved through the locally applied correction electric field. Therefore, the rate will also be faster, so that a higher etching rate and a stronger anisotropic effect can be exerted, which is beneficial to high aspect ratio etching and improves the process window.

[0080] In some embodiments, the etching process used for trench etching is an improved Bosch process formed by optimizing the traditional Bosch process. The improved Bosch process is a pulsed plasma etching process using helium protection. Among them, the improved Bosch process uses helium (He) as the protection gas, replacing the argon used in the traditional Bosch process, and uses a pulsed plasma etching method to etch the trench.

[0081] In some embodiments, the improved Bosch process includes a plurality of periodic cycle steps formed by an etching step, a passivation layer deposition step, and an etching step in sequence. In the embodiments of the present application, a pulsed plasma etching method with helium protection is used when performing the improved Bosch process. Specifically, in the pulsed plasma etching method, it includes a plurality of periodic pulse cycle steps formed by alternately turning on and off the bias power.

[0082] Among them, in the above-mentioned plurality of periodic cycle steps formed by an etching step, a passivation layer deposition step, and an etching step, the pulsed plasma etching method is used in the etching step (link). When the bias power is turned on, high-energy ions are generated to bombard the surface of the substrate 100 to activate the etching reaction. When the bias power is turned off, the plasma extinguishes or the power drops suddenly, so that the deposited passivation layer can well protect the sidewalls and discharge by-products. By changing the pulse frequency and duty cycle, the control of plasma parameters can be realized, making the distribution of reaction particles in the plasma more uniform, and finally improving the distribution of the plasma inside the trench.

[0083] Compared with the continuous plasma etching method used in the traditional Bosch process, the pulsed plasma etching method adopted in the embodiments of the present application periodically turns on and off the bias power. During each pulse cycle, the ions are in a high-energy state for a relatively short time, thereby reducing the cumulative damage to the surface of the substrate 100 material and giving time for charge release, avoiding charge accumulation. Using helium gas with higher thermal conductivity as the protective gas can accelerate the uniform distribution of the plasma and the exclusion of reaction products. Therefore, by adopting the pulsed plasma etching method with helium protection, the plasma distribution can be further optimized, helping charge release, reducing etching damage, and optimizing the anisotropy of etching, avoiding the phenomenon that the trenches in the formation are inclined to one side due to uneven lateral etching, so as to further reduce or avoid the occurrence of trench tilt.

[0084] Furthermore, since helium is used to replace traditional argon as the carrier gas, and the bombardment force of helium is weaker, it is possible to allow etching to be carried out at a relatively high bias power and low pressure. While enhancing the physical bombardment effect, improving the plasma directivity, and improving trench tilt, it also effectively reduces sidewall damage and improves the reliability of the device.

[0085] It should be noted that when allowing etching to be carried out at a relatively high bias power and low pressure, the upper limit value of the power that can be applied to the local correction electric field (corresponding to 5% of the bias power) will also be increased, and the rate at which the plasma reaches the bottom of the trench will be faster. This means that when improving the trench tilt at a larger angle, there will be a stronger regulation ability and an effective improvement in etching efficiency.

[0086] In some embodiments, when etching, the temperature is 10°C to 60°C. For example, the temperature can be 10°C, 11°C, 15°C, 20°C, 25°C, 35°C, 42°C, 48°C, 53°C, 59°C, or 60°C, etc., but is not limited thereto.

[0087] In some embodiments, when etching, the pressure is 1 mtorr to 100 mtorr. For example, the pressure can be 1 mtorr, 2 mtorr, 5 mtorr, 10 mtorr, 15 mtorr, 20 mtorr, 30 mtorr, 40 mtorr, 50 mtorr, 60 mtorr, 70 mtorr, 80 mtorr, 90 mtorr, 95 mtorr, 99 mtorr, or 100 mtorr, etc., but is not limited thereto.

[0088] In some embodiments, during etching, the source power is 100 W to 2000 W. For example, the source power can be 100 W, 150 W, 200 W, 300 W, 400 W, 500 W, 800 W, 1000 W, 1200 W, 1500 W, 1900 W, 2000 W, etc., but is not limited thereto.

[0089] In some embodiments, during etching, the bias power is 10 W to 500 W. For example, the bias power can be 10 W, 15 W, 20 W, 40 W, 70 W, 100 W, 150 W, 200 W, 250 W, 300 W, 350 W, 400 W, 480 W, 500 W, etc., but is not limited thereto.

[0090] The following will specifically describe an etching apparatus according to an embodiment of the present application in conjunction with the accompanying drawings.

[0091] An etching apparatus according to an embodiment of the present application can be used to implement the method for improving the topography of a high aspect ratio etching structure according to the embodiment of the present application described above.

[0092] Refer to Figure 4 、 Figure 5 and Figure 6 . An etching apparatus according to an embodiment of the present application includes a chamber 10, a gas storage module 22, and a local correction electric field generation module 24.

[0093] Among them, the chamber 10 is used to implement the etching process. A susceptor 11 (such as an electrostatic chuck) is provided on the bottom inside the chamber 10. The susceptor 11 has a horizontal upper surface for horizontally placing a substrate 100 to be processed (such as a silicon wafer).

[0094] In some embodiments, a second electrode (bias electrode, not shown) is further provided on the susceptor 11 for applying a bias power to the entire substrate 100. The second electrode is connected to a bias power supply for applying the bias power.

[0095] In some embodiments, an air inlet portion 12 (such as a gas injection nozzle) is provided on the top inside the chamber 10 for inputting a process gas for etching into the chamber 10.

[0096] In some embodiments, an exhaust portion 13 (such as an exhaust port) for exhausting gas is provided on the bottom inside the chamber 10. The exhaust portion 13 is located on the side of the susceptor 11.

[0097] In some embodiments, the chamber 10 can be an inductively coupled plasma (ICP) etching chamber.

[0098] In some embodiments, the chamber 10 can be a capacitively coupled plasma (CCP) etching chamber.

[0099] The gas storage module 22 is disposed in the cavity 10. The gas storage module 22 has a first space 201, and the first space 201 is located above the base 11. There is a second space 202 below the first space 201, and the base 11 is accommodated in the second space 202. The first space 201 and the second space 202 are communicatively isolated through the bottom 2011 of the first space.

[0100] The gas storage module 22 is used to form a plasma with a continuously increasing density in its first space 201, and under the natural action of pressure, the plasma is dispersed and diffused downward through the bottom 2011 of the first space into the second space 202, so that when reaching the surface of the substrate 100 disposed on the base 11, a plasma with a uniform density is formed on the entire surface of the substrate 100, and then through the homogenized plasma, the surface of the substrate 100 is etched downward to form a plurality of trenches (high aspect ratio etching structures) distributed on the substrate 100.

[0101] In some embodiments, the gas storage module 22 includes an air flow dispersion plate 221. Among them, the air flow dispersion plate 221 is horizontally disposed above the base 11; and the side surface of the air flow dispersion plate 221 is sealingly connected to the side wall of the cavity 10, so that relatively closed first space 201 and second space 202 are respectively formed in the cavity 10 on the upper and lower sides of the air flow dispersion plate 221. The side wall and the top wall of the cavity 10 for enclosing the first space 201 and the air flow dispersion plate 221 together constitute the gas storage module 22. The intake part 12 is disposed on the top in the cavity 10, and the intake part 12 is communicated with the top of the first space 201. The intake part 12 is used to introduce process gas into the first space 201 to further form a plasma of the process gas. Both the base 11 and the exhaust part 13 are located in the second space 202.

[0102] In some embodiments, a radio frequency coil is disposed on the upper part of the cavity 10, which is used to excite the process gas input into the first space 201 to form a plasma at startup, and under the action of the bias power (bias voltage) applied through the second electrode and the pressure, the formed plasma is diffused downward to the surface of the substrate 100 placed on the base 11 through the dispersion of the air flow dispersion plate 221 for trench etching.

[0103] In some embodiments, a plurality of nano-pores 222 (hollow parts) are provided on the surface of the air flow dispersion plate 221, so that the first space 201 and the second space 202 are communicatively isolated through the nano-pores 222 on the air flow dispersion plate 221 serving as the bottom 2011 of the first space. The nano-pores 222 are used for the downward passage of the plasma formed in the first space 201.

[0104] In some embodiments, the nano-pores 222 on the surface of the gas flow dispersion plate 221 are perpendicular to the surface of the horizontally arranged substrate 100. Moreover, the projection in the vertical direction of any one of the outermost nano-pores 222 on the surface of the gas flow dispersion plate 221 is located outside the substrate 100. In this way, it is ensured that the plasma gas flow diffused from the gas flow dispersion plate 221 to the surface of the substrate 100 can cover the entire surface of the substrate 100.

[0105] In some embodiments, when the substrate 100 is horizontally arranged on the base 11, the center of the gas flow dispersion plate 221 is aligned (or substantially aligned) with the center of the substrate 100. The arrangement form of the nano-pores 222 on the surface of the gas flow dispersion plate 221 is as follows: along the direction from the center of the substrate 100 to the edge, the nano-pores 222 are distributed on the surface of the gas flow dispersion plate 221 from sparse to dense, so that the plasma in the first space 201 passes through the gas flow dispersion plate 221 and is vertically dispersed by the nano-pores 222 into multiple plasma gas flows from sparse to dense, and diffuses downward toward the surface of the substrate 100.

[0106] In some embodiments, the pore shape of the nano-pores 222 is preferably a round hole.

[0107] In some embodiments, at each position on the surface of the gas flow dispersion plate 221, the aperture diameters of the nano-pores 222 are the same. In this case, the number of nano-pores 222 gradually increases along the direction from the center to the edge of the surface of the gas flow dispersion plate 221 (i.e., along the direction from the center to the edge of the surface of the substrate 100). In other words, along the direction from the center to the edge of the surface of the gas flow dispersion plate 221, the pore occupancy rate of the nano-pores 222 (the area ratio of the nano-pores 222 in the unit area on the surface of the gas flow dispersion plate 221) gradually increases.

[0108] In some embodiments, at various positions on the surface of the gas flow dispersion plate 221, the pore diameters of the nano-pores 222 are consistent, and the pore diameter of the nano-pores 222 is 1 nm to 100 nm. For example, the pore diameter of the nano-pores 222 can be 1 nm, 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 98 nm, 99 nm or 100 nm, etc., but not limited thereto. Moreover, the pore occupancy of the nano-pores 222 on the gas flow dispersion plate 221 gradually increases and varies between 10% and 50% along the direction from the center of the substrate 100 to the edge. For example, in the area closest to the center of the gas flow dispersion plate 221, the pore occupancy of the nano-pores 222 is 10%, and in the area farthest from the center of the gas flow dispersion plate 221, the pore occupancy of the nano-pores 222 is 50%, and in other areas between the above two areas, the pore occupancy of the nano-pores 222 gradually increases and varies within the range greater than 10% and less than 50%.

[0109] Furthermore, the pore occupancy of the nano-pores 222 on the gas flow dispersion plate 221 gradually increases and varies between 10% - 45%, 10% - 40%, 10% - 35%, 10% - 30%, 15% - 50%, 15% - 45%, 15% - 40%, 15% - 35%, 20% - 50%, 20% - 45%, 20% - 40%, 25% - 50%, 25% - 45% or 30% - 50% along the direction from the center of the substrate 100 to the edge, but not limited thereto.

[0110] In some embodiments, the arrangement form of each nano-pore 222 is as follows: along the direction from the center of the substrate 100 to the edge (along the direction from the center to the edge of the surface of the gas flow dispersion plate 221), the pore diameters of the nano-pores 222 are distributed from small to large, so that the plasma is vertically dispersed by the nano-pores 222 on the gas flow dispersion plate 221 into multiple plasma gas flows with diameters increasing from small to large, and diffuses downward into the second space 202. In this case, the number of nano-pores 222 gradually increases along the direction from the center to the edge of the gas flow dispersion plate 221. Or, along the direction from the center to the edge of the gas flow dispersion plate 221, the pore occupancy of the nano-pores 222 gradually increases.

[0111] In some embodiments, the pore diameter of each nano-pore 222 gradually increases and varies between 1 nm and 100 nm along the direction from the center to the edge of the surface of the gas flow dispersion plate 221. For example, in the region closest to the center of the gas flow dispersion plate 221, the pore diameter of the nano-pores 222 is 1 nm, and in the region farthest from the center of the gas flow dispersion plate 221, the pore diameter of the nano-pores 222 is 100 nm. And in other regions between the above two regions, the pore diameter of the nano-pores 222 gradually increases and varies within the range greater than 1 nm and less than 100 nm. Also, along the direction from the center to the edge of the gas flow dispersion plate 221, the pore occupancy rate of the nano-pores 222 gradually increases and varies between 10% and 50%.

[0112] Furthermore, the pore diameter of each nano-pore 222 gradually increases and varies between 2 nm and 95 nm, 3 nm and 90 nm, 4 nm and 85 nm, 5 nm and 80 nm, 6 nm and 75 nm, 7 nm and 70 nm, 8 nm and 65 nm, 9 nm and 60 nm, or 10 nm and 55 nm along the direction from the center to the edge of the surface of the gas flow dispersion plate 221, but is not limited thereto.

[0113] In some embodiments, the distance (the first distance) between the air inlet part 12 and the surface of the substrate 100 when disposed on the base 11 is 100 mm to 200 mm. For example, the first distance is 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 195 mm, or 200 mm, etc., but is not limited thereto.

[0114] In some embodiments, the distance (the second distance) between the gas flow dispersion plate 221 and the surface of the substrate 100 when disposed on the base 11 is 20 mm to 60 mm. For example, the second distance is 20 mm, 21 mm, 22 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 58 mm, 59 mm, or 60 mm, etc., but is not limited thereto.

[0115] When specifically setting the first distance and the second distance, it is a necessary condition that the process gas can reach the surface of the substrate 100 without generating turbulent flow.

[0116] In some embodiments, the gas flow dispersion plate 221 is made of an insulating material with stable chemical properties in the etching chamber 10, so that the plasma is not grounded when passing through the gas flow dispersion plate 221. For example, the manufacturing material of the gas flow dispersion plate 221 includes silicon oxide, silicon nitride, aluminum oxide, or aluminum nitride, etc., but is not limited thereto.

[0117] Therefore, when the plasma in the first space 201 diffuses downward through the nano pores 222 on the gas flow dispersion plate 221 to the surface of the substrate 100 under the action of pressure, the gas volume of the gas flow reaching the edge can be made to tend to be the same as that of the gas flow reaching the center, and the density of the gas flow from the center to the edge of the surface of the substrate 100 also tends to be the same, as shown by the downward hollow arrows in Figure 6 . Thus, when the plasma contacts the surface of the substrate 100, it is evenly distributed on the surface of the substrate 100, thereby improving the process uniformity.

[0118] The local correction electric field generation module 24 is provided on the base 11. The local correction electric field generation module 24 is used to apply the generated additional local correction electric field to the target improvement area on the substrate 100 during the etching process according to the obtained data of the trench tilt occurrence area and the trench tilt degree, and adjust the electric field intensity of the local correction electric field to a preset value.

[0119] Reference Figure 4 and Figure 5 . In some embodiments, the surface of the substrate 100 includes a central region A and an edge region B surrounding the outside of the central region A, and the target improvement area is located in the edge region B. The local correction electric field generation module 24 includes a plurality of independently provided first electrodes 241. The setting positions of the first electrodes 241 on the base 11 are located on the edge region B and are evenly arranged around the central region A. An alternating voltage is applied to the first electrode 241 corresponding to the position of the target improvement area to generate a local correction electric field.

[0120] It should be noted that between the first electrodes 241 and between the first electrode 241 and the second electrode are electrically insulated from each other and no electrical interconnection is generated.

[0121] In some embodiments, each first electrode 241 is connected to a dedicated power supply. The dedicated power supply is used to apply an alternating voltage to the first electrode 241 corresponding to the position of the target improvement area to generate a local correction electric field.

[0122] The dedicated power supply can be a power supply independently provided outside the etching equipment. Alternatively, the dedicated power supply can be established based on the bias power supply provided by the etching equipment itself.

[0123] In some embodiments, when reaching the preset value of the electric field intensity, the magnitude of the power applied by the dedicated power supply to the first electrode 241 is 1% to 5% of the bias power applied by the bias power supply, and the magnitude of the preset value is proportional to the magnitude of the trench tilt degree.

[0124] In some embodiments, the number of the first electrodes 241 is 4 to 16, and they are evenly distributed around the central region A. For example, the number of the first electrodes 241 can be 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16.

[0125] In this embodiment, the number of the first electrodes 241 is 8. Among them, the shape of the first electrodes 241 is a sector block, and the first electrodes 241 are arranged on the bottom of the base 11 in a manner that their sector ends are adjacent to each other, forming a discontinuous circular ring, as Figure 5 shown.

[0126] In some embodiments, the etching equipment is used to perform a pulsed plasma etching process protected by helium.

[0127] In some embodiments, by setting a control module, the dedicated power supply is controlled to control the opening and closing of the dedicated power supply and the magnitude of the power applied to the first electrodes 241.

[0128] In some embodiments, the control module is arranged in the control system of the etching equipment. Alternatively, the control module is the control system of the etching equipment.

[0129] In some embodiments, the control system of the etching equipment includes a host computer and / or a slave computer.

[0130] Therefore, in the embodiment of the present application, by arranging a gas storage module 22 in the cavity 10, first, through pressurized gas storage, the density of the plasma formed in the first space 201 is increased and homogenized, and then through the gas flow dispersion plate 221 with nano pores 222, the plasma is dispersed and diffused downward into the second space 202, realizing the uniform distribution of the plasma on the entire surface of the substrate 100; furthermore, by adding a local correction electric field generation module 24 on the base 11 corresponding to the edge region B of the substrate 100 and including a plurality of first electrodes 241, an electrostatic field with adjustable region and adjustable intensity is constructed. Through the locally applied correction electric field, better etching in the depth direction can be achieved, so the rate will be faster, and higher etching rate and stronger anisotropic effect can be exerted, which is beneficial to high aspect ratio etching and improves the process window. In addition, by using helium with weaker bombardment force instead of traditional argon as the carrier gas, etching can be allowed to be carried out at a relatively high bias power and low pressure, which plays a role in enhancing the physical bombardment effect, improving the directivity of the plasma, and improving the etching efficiency. Thus, by effectively improving the abnormal morphology of the etching tilt generated on the substrate 100, the electrical performance and mechanical reliability of the trench are ensured, thereby improving the yield and stability of the device.

[0131] Figure 8 shows the known trench tilt conditions (for exampleFigure 7 The vertical topography of the trenches on the substrate obtained after improvement using the method (or etching equipment) for improving the topography of high aspect ratio etching structures according to the embodiments of the present application (in the case of the trench inclination shown). Figure 8 In Figure 1, label 1 indicates a depth of 1.4086 microns in the Y direction, label 2 indicates a top width of 1.9808 microns in the X direction, and label 3 indicates a bottom width of 1.9864 microns in the X direction). Figure 8 It can be seen that after improvement, the trenches show a better topography with the inclination angle tending to 0 degrees, indicating that Figure 7 compared with, the embodiments of the present application have a significant effect of improving the trench inclination degree.

[0132] The embodiments of the present application also provide a semiconductor structure, which includes a substrate and a plurality of trenches (high aspect ratio etching structures) distributed on the substrate. Among them, the trenches are fabricated using the method for improving the topography of high aspect ratio etching structures provided in the above embodiments to reduce the inclination on the substrate. Alternatively, the trenches are fabricated using the etching equipment provided in the above embodiments to reduce the inclination on the substrate.

[0133] In some embodiments, a semiconductor structure provided by the embodiments of the present application can be applied to the field of three-dimensional advanced packaging, and the trenches formed on the substrate are used as the vertical interconnection structure of the through-silicon vias (TSVs) on the 3D integrated circuit chips.

[0134] In other aspects, the embodiments of the present application also provide an electronic device, including the semiconductor structure of the embodiments of the present application. The electronic device can be a storage device, a mobile phone, a computer, a tablet computer, a television, an artificial intelligence device, etc.

[0135] In summary, in the embodiment of the present application, by utilizing the pressure effect, the formed plasma is first pressurized and stored in the first space 201, so that the density of the plasma continuously increases. Then, under the natural action of the pressure, the plasma is dispersed through the bottom 2011 of the first space and diffused downward into the second space 202, so as to form a plasma with a uniform density on the entire surface of the substrate 100, realizing the uniform distribution of the process gas (plasma) on the entire surface of the substrate 100. During the trench etching process, according to the obtained data of the trench tilt occurrence area and the trench tilt degree, by applying an additional local correction electric field to the target improvement area on the substrate 100 and adjusting the electric field strength of the local correction electric field to a preset value, an electrostatic field with adjustable region and adjustable intensity is constructed to strengthen the anisotropic etching, thereby optimizing the gas field and the local electric field during the trench etching process, effectively solving the abnormal etching tilt morphology generated in the middle to the edge of the substrate and different regions of the edge due to the uneven distribution of the gas field and the electromagnetic field in the past, and being able to exert a higher etching rate and a stronger anisotropic effect, which is beneficial to deep high-aspect-ratio etching and improves the process window. Therefore, by effectively improving the abnormal etching tilt morphology, the electrical performance and mechanical reliability of the trench are ensured, thereby improving the yield and stability of the device. In addition, the embodiment of the present application can also improve problems such as uneven edge etching, grass phenomenon at the bottom of the edge trench, and mask missing on the edge, having a comprehensive improvement effect.

[0136] The above are only the preferred embodiments of the present application, and the embodiments are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made by using the description and drawings of the present application should be included in the protection scope of the present application by the same token.

Claims

1. A method for improving the topography of a high aspect ratio etching structure, characterized in that, Comprising: Utilizing the pressure effect, pressurizing and storing the formed plasma in the first space to continuously increase and homogenize the density of the plasma; When the air pressure in the first space reaches the critical state, enabling the plasma to be dispersed and diffused downward into the second space through the nano-pores on the bottom of the first space without being grounded under the natural action of the pressure, so that when reaching the surface of the substrate located in the second space, the plasma with uniform density is formed on the entire surface of the substrate; Etching the surface of the substrate downward through the plasma to form a plurality of high aspect ratio etching structures distributed on the substrate, and during the etching process, according to the obtained data of the inclination occurrence area and inclination degree of the high aspect ratio etching structure, applying an additional local correction electric field to the target improvement area on the substrate, and adjusting the electric field strength of the local correction electric field to a preset value; Wherein, by applying an alternating voltage, the local correction electric field is generated to enhance the physical bombardment effect and strengthen the anisotropic etching, and the magnitude of the preset value is proportional to the magnitude of the inclination degree; the critical state is a state where the intake air volume and the exhaust air volume reach dynamic equilibrium.

2. The method for improving the aspect ratio etching structure morphology according to claim 1, wherein, In the direction from the center of the substrate to the edge, enabling the plasma to be vertically dispersed into multiple plasma gas flows from sparse to dense at the bottom of the first space and diffused downward into the second space, and / or enabling the plasma to be vertically dispersed into multiple plasma gas flows with diameters increasing from small to large at the bottom of the first space and diffused downward into the second space.

3. The method for improving the aspect ratio etching structure topography according to claim 1, wherein Defining a central region and an edge region surrounding the outside of the central region on the surface of the substrate, the target improvement area is located in the edge region, the local correction electric field is applied to the edge region, and a plurality of application regions of the local correction electric field are arranged around the central region.

4. The method for improving the aspect ratio etching structure morphology according to claim 3, wherein The magnitude of the power required to be applied to the local correction electric field when reaching the preset value is 1% - 5% of the bias power applied to the entire substrate; and / or the number of the application regions of the local correction electric field is 4 - 16 evenly distributed.

5. The method for improving the aspect ratio etching structure topography according to claim 1, characterized in that The etching is carried out based on the improved Bosch process, and the improved Bosch process is a pulsed plasma etching process using helium protection; and / or during etching, the temperature is 10°C - 60°C, the pressure is 1 mtorr - 100 mtorr, the source power is 100 W - 2000 W, and the bias power is 10 W - 500 W.

6. An etching device, characterized in that, Comprising: A cavity, a pedestal is provided on the bottom inside the cavity, and the pedestal is used for setting a substrate; A gas storage module is disposed in the cavity. The gas storage module has a first space located above the base. There is a second space below the first space, and the base is accommodated in the second space. The gas storage module is used to utilize the pressure effect to pressurize and store the formed plasma in the first space, so that the density of the plasma continues to increase and become uniform. When the air pressure in the first space reaches the critical state, the plasma is naturally dispersed under the action of pressure, passes through the nano-pores on the bottom of the first space and is not grounded, and diffuses downward into the second space. When it reaches the surface of the substrate disposed on the base, the plasma with uniform density is formed on the entire surface of the substrate, and then the surface of the substrate is etched downward by the plasma to form a plurality of high aspect ratio etching structures distributed on the substrate; A local correction electric field generation module is disposed on the base. The local correction electric field generation module is used to apply the generated additional local correction electric field to the target improvement area on the substrate during the etching process according to the data of the inclination occurrence area and the inclination degree of the high aspect ratio etching structure obtained, and adjust the electric field strength of the local correction electric field to a preset value; Among them, the local correction electric field is generated by applying an alternating voltage to enhance the physical bombardment effect and strengthen the anisotropic etching. The magnitude of the preset value is proportional to the magnitude of the inclination degree; the critical state is the state where the intake air volume and the exhaust air volume reach dynamic balance.

7. The etching apparatus according to claim 6, wherein The gas storage module includes an air flow dispersion plate. The air flow dispersion plate is horizontally disposed above the base, and the side surface of the air flow dispersion plate is in close contact with the side wall of the cavity. The first space and the second space are respectively formed in the cavity on the upper and lower sides of the air flow dispersion plate. A plurality of the nano-pores are provided on the surface of the air flow dispersion plate. The nano-pores are perpendicular to the surface of the horizontally disposed substrate. The nano-pores are used to pass the plasma. The arrangement form of each nano-pore is as follows: in the direction from the center of the substrate to the edge, each nano-pore is distributed from sparse to dense, and / or the aperture of each nano-pore is distributed from small to large; and / or, the local correction electric field generation module includes a plurality of independently arranged first electrodes. The surface of the substrate includes a central region and an edge region surrounding the outside of the central region. The target improvement area is located in the edge region. The arrangement positions of the first electrodes on the base are located on the edge region and are uniformly arranged around the central region. An alternating voltage is applied to the first electrode corresponding to the position of the target improvement area to generate the local correction electric field; and / or, the etching equipment is used to perform a pulsed plasma etching process protected by helium.

8. The etching device according to claim 7, characterized in that, The gas flow dispersion plate is made of an insulating material; and / or, an air inlet part is provided on the top inside the cavity, and the air inlet part communicates with the top of the first space. The air inlet part is used for introducing process gas into the first space to form the plasma. The first distance between the air inlet part and the substrate surface during setting is 100 mm to 200 mm, and the second distance between the gas flow dispersion plate and the substrate surface during setting is 20 mm to 60 mm; and / or, the pore occupancy rate of the nano-pores on the gas flow dispersion plate gradually increases and varies between 10% and 50% along the direction from the center of the substrate to the edge; and / or, the pore diameter of the nano-pores gradually increases and varies between 1 nm and 100 nm along the direction from the center of the substrate to the edge.

9. The etching apparatus according to claim 7, wherein A second electrode is further provided on the base, which is used to apply a bias power to the whole substrate. The magnitude of the power required to be applied to the first electrode when reaching the preset value is 1% to 5% of the applied bias power; and / or, the number of the first electrodes is 4 to 16.

10. A semiconductor structure, comprising a substrate and a plurality of high aspect ratio etching structures disposed on the substrate, characterized in that, The high aspect ratio etching structure is fabricated by using the high aspect ratio etching structure morphology improvement method according to any one of claims 1-5 or the etching equipment according to any one of claims 6-9.

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