Plasma etching apparatus

Abstract

The application provides a plasma etching device, which comprises an etching cavity, a plasma generating assembly, a carrier, a Faraday cage and an inclination angle adjusting frame. The Faraday cage comprises a conductive cage top, which is arranged in the etching cavity and is spaced apart from a bearing surface. A plane where the cage top is located has an inclination angle with the bearing surface. The cage top is installed above the carrier through the inclination angle adjusting frame, and the inclination angle adjusting frame is used for adjusting the inclination angle of the plane where the cage top is located relative to the bearing surface. Alternatively, the bearing surface has an inclination angle with a bottom wall of the etching cavity. The carrier is installed in the etching cavity through the inclination angle adjusting frame, and the inclination angle adjusting frame is used for adjusting the inclination angle of the bearing surface relative to the bottom wall of the etching cavity. The plasma etching device can directly adjust the cage top or the carrier through the inclination angle adjusting frame, so that the etching inclination angle is changed, and the flexibility of changing the etching angle is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor etching technology, and more specifically to a plasma etching apparatus. Background Technology

[0002] Plasma etching is a core process in semiconductor manufacturing, widely used in the etching of precision components such as chips and displays. During the operation of a plasma etching apparatus, a large number of charged plasma particles are generated within the etching chamber. By applying a bias voltage to the carrier through a bias power supply, the charged particles are driven to move in a directional and accelerated manner and bombard the surface of the object to be etched on the carrier to perform the etching operation.

[0003] In the fields of semiconductor manufacturing and micro / nano fabrication, applications such as high aspect ratio structure etching, diffraction grating mold manufacturing, and photonic crystal processing increasingly require tilted etching processes. Taking diffraction gratings as an example, their manufacturing requires the formation of periodic groove structures with specific tilt angles on the substrate material. This necessitates that ions in the plasma bombard the wafer surface at a certain incident angle during the etching process.

[0004] In existing plasma etching devices, the ion incident direction can be changed by introducing a tilted Faraday cage, or the etching angle can be changed by tilting the carrier. However, these solutions can only achieve tilted etching at a fixed angle, and the range of incident angles that can be achieved is usually limited. If the etching angle needs to be changed, a Faraday cage or carrier with a different tilt angle must be replaced, which is not very flexible. Summary of the Invention

[0005] The main technical problem solved by this invention is that the plasma etching device can only achieve etching at a fixed tilt angle, resulting in poor flexibility.

[0006] To address the aforementioned technical problems, this application provides a plasma etching apparatus, including an etching chamber, a plasma generating assembly, a carrier, a Faraday cage, and a tilt angle adjustment frame. The etching chamber generates plasma within it; the carrier is disposed within the etching chamber and has a bearing surface for supporting the material to be etched; the Faraday cage includes a conductive cage top, which is disposed within the etching chamber and spaced apart from the bearing surface.

[0007] The top plane of the cage has an angle with the bearing surface. The top of the cage is installed above the bearing body by an angle adjustment frame. The angle adjustment frame is used to adjust the angle of inclination of the top plane of the cage relative to the bearing surface. The angle adjustment frame includes a first drive assembly and at least two first pillars. Each first pillar supports the top of the cage. The first drive assembly is used to drive at least one first pillar to move in order to adjust the height of at least one first pillar in order to adjust the angle of inclination of the top of the cage.

[0008] Alternatively, the bearing surface has an angle with the bottom wall of the etching cavity, and the bearing is installed in the etching cavity by a tilt angle adjustment frame. The tilt angle adjustment frame is used to adjust the tilt angle of the bearing surface relative to the bottom wall of the etching cavity. The tilt angle adjustment frame includes a second drive assembly and at least two second pillars, each second pillar supporting the bearing. The second drive assembly is used to drive at least one second pillar to move to adjust the height of at least one second pillar to adjust the tilt angle of the bearing surface.

[0009] In one embodiment, when the top of the cage is mounted above the carrier via an angle adjustment bracket, the first drive assembly is located outside the etching cavity, one end of the first pillar is located outside the etching cavity and connected to the first drive assembly, and the other end of the first pillar is located inside the etching cavity and connected to the top of the cage.

[0010] The plasma etching apparatus also includes a magnetohydrodynamic sealing assembly, which is mounted on the etching chamber and is used to dynamically vacuum seal the etching chamber with the first pillar.

[0011] In one embodiment, the top of the cage includes an edge support, a support frame, and multiple openings. The support frame is a dense structure made of conductive material. The support frame extends within the annular structure enclosed by the edge support and is connected to the edge support. The support frame includes multiple support rods. The multiple support rods interlock with each other to separate the multiple openings. The openings are provided with multiple through holes that penetrate the outer side and the inner side of the top of the cage, so that plasma can enter the Faraday cage through the through holes in a direction perpendicular to the top of the cage.

[0012] In one embodiment, a hollow structure is formed inside at least part of the support frame and / or at least part of the edge support portion. The hollow structure includes an inlet and an outlet for introducing non-conductive coolant.

[0013] In one embodiment, the top of the cage is made of high-purity aluminum with a purity of not less than 99.999%, and the surface of the high-purity aluminum is formed into an anodized aluminum ceramic layer through an anodizing process.

[0014] In one embodiment, the top of the cage includes a mesh-shaped first cage and a mesh-shaped second cage. The first cage has a plurality of first through holes penetrating the outer side and the inner side of the first cage. The second cage has a plurality of second through holes penetrating the outer side and the inner side of the second cage. The first cage and the second cage are arranged opposite to each other and have a gap between them. The gap communicates with the interior of the etching cavity so that the process gas in the etching cavity can enter the gap. The first through holes are used to allow plasma to enter the gap in a direction perpendicular to the first cage, and the second through holes are used to allow particles in the gap to pass through.

[0015] In one embodiment, the second cage is positioned closer to the carrier than the first cage; the opening ratio of the first cage is less than or equal to the opening ratio of the second cage.

[0016] In one embodiment, the diameter of the first through hole is larger than the diameter of the second through hole, and the density of the first through hole is smaller than the density of the second through hole.

[0017] Alternatively, the diameter of the first through hole is equal to the diameter of the second through hole, and the density of the first through hole is less than or equal to the density of the second through hole.

[0018] In one embodiment, when the top of the cage is mounted above the carrier via a tilt angle adjustment frame, the plasma etching apparatus further includes:

[0019] An adjustable bias power supply is used to provide a bias voltage to the top of the cage to form an asymmetric electric field in the sheath below the top of the cage for deflecting incident ions.

[0020] The sheath potential monitoring unit is used to detect the sheath potential at at least two monitoring positions in the area between the top of the cage and the bearing surface. Each monitoring position is distributed along the direction in which the top of the cage is inclined relative to the bearing surface, and has a different height relative to the bearing surface.

[0021] The control unit, connected to the sheath potential monitoring unit and the adjustable bias power supply, is used to determine the target bias voltage according to the target incident angle and control the adjustable bias power supply to provide the target bias voltage to the top of the cage; it receives the sheath potential at at least two monitoring positions output by the sheath potential monitoring unit, determines the potential difference based on a preset reference and the sheath potential at each monitoring position, generates a bias correction amount according to the potential difference, and controls the adjustable bias power supply to superimpose the bias correction amount onto the target bias voltage so that the ions in the plasma are incident at the target incident angle.

[0022] In one embodiment, the sheath potential monitoring unit includes at least two Langmuir probes arranged in a direction inclined relative to the bearing surface at the top of the cage, with each Langmuir probe corresponding to a monitoring position.

[0023] In one embodiment of the plasma etching apparatus of this application, the top of the cage is mounted above the support body via a tilt angle adjustment frame. The plane containing the top of the cage has an angle with the support surface. The tilt angle adjustment frame is used to adjust the tilt angle of the plane containing the top of the cage relative to the support surface, thereby adjusting the etching tilt angle. In another embodiment, the support body is mounted inside the etching chamber via a tilt angle adjustment frame. The support surface has an angle with the bottom wall of the etching chamber. The tilt angle adjustment frame is used to adjust the tilt angle of the support surface relative to the bottom wall of the etching chamber, thereby adjusting the etching tilt angle. When it is necessary to change the etching tilt angle, the tilt angle of the top of the cage or the support body can be directly adjusted via the tilt angle adjustment frame, thereby changing the etching tilt angle without the need to replace different Faraday cages or support bodies, thus improving the flexibility of changing the etching angle. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the plasma etching apparatus provided in the first embodiment of this application;

[0025] Figure 2 This is a schematic diagram of the plasma etching apparatus provided in the second embodiment of this application;

[0026] Figure 3 This is a schematic diagram of the plasma etching apparatus provided in the third embodiment of this application;

[0027] Figure 4 A schematic diagram of the first support column and the top of the cage provided in an embodiment of this application;

[0028] Figure 5 A schematic diagram of the top structure of a Faraday cage according to an embodiment of this application;

[0029] Figure 6 A schematic diagram of the structure of the top of the Faraday cage and the first support column provided in an embodiment of this application;

[0030] Figure 7 This is a schematic diagram of the internal structure of the top of the cage according to an embodiment of this application;

[0031] Figure 8 A cross-sectional view of the top of the cage and the first support column provided in an embodiment of this application;

[0032] Figure 9 This is a schematic diagram of the plasma etching apparatus provided in the fourth embodiment of this application;

[0033] Figure 10 A schematic diagram of the top structure of the Faraday cage provided in another embodiment of this application;

[0034] Figure 11 for Figure 10 Exploded view;

[0035] Figure 12 for Figure 10 A sectional view;

[0036] Figure 13 This is a schematic diagram of the plasma etching apparatus provided in the fifth embodiment of this application;

[0037] Figure 14 A schematic diagram of the top structure of the Faraday cage provided in another embodiment of this application;

[0038] Figure 15 A flowchart of a plasma etching angle control method provided in one embodiment of this application;

[0039] Figure 16 A flowchart of a plasma etching angle control method provided in another embodiment of this application;

[0040] in, Figure 1 and Figure 13 In this context, PL stands for Plasma.

[0041] Labeling: Etching cavity 10, air inlet 11, plasma excitation assembly 21, coil RF power supply 211, induction coil 212, delivery pipeline 22, exhaust pipeline 23, carrier 30, carrier surface 31, first bias power supply 40, cage top 50, incident surface 51, exit surface 52, edge support 53, annular side 531, second channel 532, support frame 54, support rod 541, first channel 542, branch opening 5421, opening 55, through hole 551, first cage Body 56, first through hole 561, first incident surface 562, first exit surface 563, second cage 57, second through hole 571, second incident surface 572, second exit surface 573, gap 58, insulating connection part 59, tilt angle adjustment frame 60, first drive assembly 61, first drive element 611, first support column 62, liquid inlet channel 621, liquid outlet channel 622, second support column 63, adjustable bias power supply 70, control unit 80, first Langmuir probe 91, second Langmuir probe 92. Detailed Implementation

[0042] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the invention. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present invention are not shown or described in the specification. This is to avoid obscuring the core parts of the invention with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0043] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0044] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this invention, unless otherwise specified, include both direct and indirect connections (linkages).

[0045] like Figure 1 and Figure 2 As shown, this application provides a plasma etching apparatus, which includes an etching chamber 10, a plasma generation assembly, a carrier 30, and a Faraday cage. The etching chamber 10 contains an etching cavity, which serves as the site for plasma distribution and etching. To facilitate the demonstration of the components inside the etching chamber 10, Figure 2 The image only shows a portion of the etching chamber 10. An air inlet 11 is provided on the top or side of the etching chamber 10, which allows process gas to enter the etching chamber 10.

[0046] The plasma generation assembly is used to generate plasma within the etching chamber 10. Specifically, in one embodiment, the plasma generation assembly includes a gas delivery assembly, a plasma excitation assembly 21, and a pumping assembly. The gas delivery assembly is used to deliver process gas into the etching chamber 10. The process gas can be a reactive gas commonly used in plasma etching processes, such as O2, Cl2, HBr, CF4, etc. The gas delivery assembly may include, for example, a gas source for storing the process gas and a delivery pipeline 22. The delivery pipeline 22 connects the gas source to the inlet 11 of the etching chamber 10 to deliver the process gas from the gas source into the etching chamber 10. In addition, the gas delivery assembly may also include a gas source valve, which is disposed on the delivery pipeline 22 and can be used to control the flow rate of the delivered process gas.

[0047] The plasma excitation assembly 21 is used to excite process gas into plasma. In one embodiment, the plasma excitation assembly 21 generates plasma through radio frequency inductively coupled gas discharge. For example, the plasma excitation assembly 21 includes an electrically connected coil radio frequency power supply 211 and an induction coil 212. The coil radio frequency power supply 211 supplies power to the induction coil 212 to apply power to the induction coil 212, which generates an alternating electromagnetic field within the etching cavity 10 to excite the process gas discharge and ionize the process gas into plasma. To avoid contamination, the induction coil 212 can be placed outside the etching cavity 10.

[0048] Generally, the plasma etching apparatus also includes a control unit. The control unit can control the opening of the gas source valve to allow the gas delivery assembly to deliver process gas into the etching chamber 10. The control unit can control the flow rate of the process gas by controlling the opening degree of the gas source valve. After the gas delivery assembly starts delivering process gas, and after the pressure inside the etching chamber 10 reaches a set pressure, the control device controls the coil RF power supply 211 to supply power to the induction coil 212, thereby providing RF power higher than 1 kilowatt to the induction coil 212. In other embodiments, the plasma excitation assembly 21 can also generate plasma through capacitive coupling.

[0049] A gas extraction assembly is used to extract the reaction gas within the etching chamber 10. The gas extraction assembly may include, for example, an exhaust pipe 23 and a pump. The exhaust pipe 23 connects the pump to the etching chamber, enabling the pump to extract the reaction gas from the etching chamber 10 through the exhaust pipe 23. The control unit can control the gas extraction assembly to extract the reaction gas after the plasma stops bombarding the material to be etched, thereby controlling the gas pressure inside the etching chamber 10 and controlling the discharge of reaction byproducts.

[0050] The carrier 30 is disposed within the etching cavity 10. The carrier 30 is typically a chuck, such as an electrostatic chuck or a mechanical chuck. The carrier 30 has a bearing surface 31, which is used to bear the material to be etched, such as a wafer.

[0051] In one embodiment, the plasma etching apparatus further includes a first bias power supply 40, which is electrically connected to the carrier 30 and is used to apply a bias voltage to the carrier 30. When plasma is present in the etching chamber 10, the carrier 30 can attract charged particles in the plasma to accelerate towards the object to be etched and the carrier 30. The first bias power supply 40 can provide a radio frequency bias voltage to the carrier 30, and the etching rate can be controlled by adjusting the bias power. A control device can control the first bias power supply 40 to provide a radio frequency bias voltage to the carrier 30 to attract plasma to bombard the object to be etched on the carrier 30.

[0052] The Faraday cage includes a conductive cage top 50, which is made of a conductive material. Preferably, the cage top 50 can be made of metal. The cage top 50 is disposed within the etching cavity 10 and is spaced above the support body 30, with the cage top 50 and the support surface 31 spaced apart.

[0053] like Figure 2 and Figure 3 As shown, the plasma etching apparatus also includes a tilt angle adjustment bracket 60. (As indicated...) Figure 2As shown, in one embodiment, the plane of the top 50 of the cage is inclined to the bearing surface 31. It is understood that the top 50 of the cage is typically a thin sheet structure with a thickness of 1.5mm-3.5mm. The top 50 of the cage has an incident surface 51 and an exit surface 52 arranged opposite to each other along its thickness direction. The incident surface 51 is used for particle incidence, and the exit surface 52 is used for particle exit. The plane of the top 50 of the cage refers to either the plane of the incident surface 51 or the plane of the exit surface 52. In this embodiment, the bearing surface 31 is typically parallel to the bottom wall of the etching cavity 10, i.e., the bearing surface 31 is horizontally arranged, while the top 50 of the cage is inclined relative to the bottom wall of the etching cavity 10. The top of the cage 50 is mounted above the support 30 via a tilt angle adjustment bracket 60. The tilt angle adjustment bracket 60 is used to adjust the tilt angle of the plane where the top of the cage 50 is located relative to the support surface 31. When the tilt angle of the plane where the top of the cage 50 is located relative to the support surface 31 is changed, the etching tilt angle can be changed.

[0054] In another embodiment, such as Figure 3 As shown, the bearing surface 31 has an inclination angle with the bottom wall of the etching chamber 10, that is, the bearing surface 31 is inclined relative to the bottom wall of the etching chamber 10. In this embodiment, the plane containing the top 50 of the cage can be horizontally positioned. The bearing 30 is installed in the etching chamber 10 via an inclination angle adjustment bracket 60, which is used to adjust the inclination angle of the bearing surface 31 relative to the bottom wall of the etching chamber 10. When the inclination angle of the bearing surface 31 is changed, the etching angle of the plasma can be changed.

[0055] In one embodiment of the plasma etching apparatus of this application, the top 50 of the cage is mounted above the support 30 via a tilt angle adjustment frame 60. The plane containing the top 50 of the cage has an angle with the support surface 31. The tilt angle adjustment frame 60 is used to adjust the tilt angle of the plane containing the top 50 of the cage relative to the support surface 31, thereby adjusting the etching tilt angle. In another embodiment, the support 30 is mounted inside the etching cavity 10 via the tilt angle adjustment frame 60. The support surface 31 has an angle with the bottom wall of the etching cavity 10. The tilt angle adjustment frame 60 is used to adjust the tilt angle of the support surface 31 relative to the bottom wall of the etching cavity 10, thereby adjusting the etching tilt angle. When it is necessary to change the etching tilt angle, the tilt angle of the top 50 of the cage or the support 30 can be directly adjusted via the tilt angle adjustment frame 60, thereby changing the etching tilt angle without the need to replace different Faraday cages or support 30s, thus improving the flexibility of changing the etching angle.

[0056] In one embodiment, such as Figure 2As shown, when the top 50 of the cage is mounted above the support body 30 via the tilt angle adjustment frame 60, the tilt angle adjustment frame 60 includes a first drive assembly 61 and at least two first support columns 62. Each first support column 62 supports the top 50 of the cage, and the first drive assembly 61 is used to drive at least one first support column 62 to move, so as to adjust the height of at least one first support column 62, thereby adjusting the tilt angle of the top 50 of the cage.

[0057] Specifically, the first drive assembly 61 is connected to each of the first pillars 62. The first drive assembly 61 includes at least two first drive elements 611, and the output end of each first drive element 611 is connected to each of the first pillars 62. The height of each first pillar 62 can be adjusted by extending and retracting the output end of the first drive element 611. The first drive element 611 may be a motor.

[0058] In one embodiment, at least two first supports 62 are evenly distributed and parallel to each other along the periphery of the support body 30. For example, in Figure 2 In one embodiment, there are three first pillars 62. One first pillar 62 is used to support the high part of the top 50 of the cage body, and the other two first pillars 62 are used to support the low part of the top 50 of the cage body. Of course, it is also possible that one first pillar 62 is used to support the low part of the top 50 of the cage body, and the other two first pillars 62 are used to support the high part of the top 50 of the cage body.

[0059] like Figure 4 As shown, taking the parallel distribution of two first supports 62 as an example, H1 represents the vertical height of the first support 62 at the lower part of the top 50 of the cage, and H2 represents the vertical height of the first support 62 at the higher part of the top 50 of the cage. The horizontal distance between the first support 62 at the lower part of the top 50 of the cage and the first support 62 at the higher part of the top 50 of the cage is L. α is the angle of inclination between the plane containing the top 50 of the cage and the horizontal plane. The geometric relationship between the angle of inclination α of the top 50 of the cage and the two first supports 62 is: tanα=(H2-H1) / L; H1 is usually measured through experimental data, and the minimum value of H1 is 25mm. When the target angle of inclination α and the fixed value of L are known, the height H1 of the first support 62 at the lower part of the top 50 of the cage can be kept constant. The angle of inclination α can be adjusted by adjusting the height H2 of the first support 62 at the higher part of the top 50 of the cage, as follows: H2=H1+Ltanα, and the minimum value of H2 is 25mm+Ltanα. The above is an example of adjusting the angle of the top 50 of the cage by adjusting the height of one of the first pillars 62. It can be understood that when there are more first pillars 62, the angle of the top 50 of the cage can also be adjusted by adjusting the height of two or more of the first pillars 62.

[0060] In one embodiment, such as Figure 2As shown, when the top 50 of the cage is mounted above the carrier 30 via the tilt angle adjustment bracket 60, the first drive assembly 61 is located outside the etching cavity 10, one end of the first pillar 62 is located outside the etching cavity 10 and connected to the first drive assembly 61, and the other end of the first pillar 62 is located inside the etching cavity 10 and connected to the top 50 of the cage. By placing the first drive assembly 61 outside the etching cavity 10, the first drive assembly 61 can be prevented from being corroded by plasma, and the external placement of the first drive assembly 61 can provide better heat dissipation and easier maintenance.

[0061] Furthermore, in one embodiment, the plasma etching apparatus further includes a magnetohydrodynamic (MHD) sealing assembly, which is mounted on the etching chamber 10 and used to dynamically vacuum seal the etching chamber 10 with the first support pillar 62. The MHD sealing assembly constrains the magnetohydrodynamic fluid through a permanent magnet circuit, causing it to fill the gap between the first support pillar 62 and the magnetic pole, forming a multi-stage liquid sealing ring. The liquid medium can continuously fill the sealing gap following the oscillation of the first support pillar 62, achieving frictionless dynamic vacuum isolation with extremely low leakage rate, no wear and dust generation, and resistance to etching and corrosive process gases. It can stably isolate the vacuum environment from the external atmosphere and maintain sealing performance even under the reciprocating oscillation of the first support pillar 62.

[0062] In one embodiment, such as Figure 3 As shown, when the carrier 30 is installed in the etching cavity 10 by the tilt angle adjustment frame 60, the tilt angle adjustment frame 60 includes a second drive assembly (not shown) and at least two second pillars 63, each second pillar 63 supporting the carrier 30. The second drive assembly is used to drive at least one second pillar 63 to move, so as to adjust the height of at least one second pillar 63, so as to adjust the tilt angle of the carrier surface 31.

[0063] Specifically, the second drive assembly is connected to each of the second pillars 63. The second drive assembly includes at least two second drive members, the output end of each of the second drive members being connected to each of the second pillars 63. The height of each of the second pillars 63 can be adjusted by extending and retracting the output ends of the second drive members. The second drive member can be a motor.

[0064] In one embodiment, at least two second pillars 63 are evenly distributed and parallel to each other along the circumferential direction of the support body 30. For example, in Figure 3In this embodiment, there are three second pillars 63. Two second pillars 63 are used to support the higher part of the support body 30, and the other second pillar 63 is used to support the lower part of the support body 30. Of course, it is also possible that two second pillars 63 are used to support the lower part of the support body 30, and the other second pillar 63 is used to support the higher part of the support body 30. The relationship between the height of the second pillar 63 and the inclination angle of the bearing surface 31 can be referred to the relationship between the height of the first pillar 62 and the inclination angle of the top 50 of the cage as described above, and will not be repeated here.

[0065] In one embodiment, such as Figure 3 As shown, the second driving assembly is disposed outside the etching cavity 10. One end of the second pillar 63 is located outside the etching cavity 10 and connected to the second driving assembly, while the other end of the second pillar 63 is located inside the etching cavity 10 and connected to the carrier 30. By disposing the second driving assembly outside the etching cavity 10, plasma corrosion of the second driving assembly can be prevented, and external placement of the second driving assembly provides better heat dissipation and easier maintenance. Furthermore, in one embodiment, the magnetohydrodynamic sealing assembly can also be used to dynamically vacuum seal the etching cavity 10 and the second pillar 63.

[0066] like Figure 5 As shown, the top 50 of the cage includes an edge support 53, a support frame 54, and multiple openings 55. The support frame 54 is a dense structure made of conductive material, used to improve the structural strength of the top 50 of the cage. Specifically, the dense structure means that no openings are provided on the outer surface of the support frame 54, and the dense structure means that plasma particles cannot penetrate the surface of the support frame 54. In some embodiments, the edge support 53 is also a dense structure made of conductive material; preferably, the edge support 53 and the support frame 54 are made of the same material.

[0067] The edge support portion 53 is a ring-shaped structure. For example, the edge support portion 53 can be a square ring-shaped structure. Preferably, the edge support portion 53 is a circular ring shape to match the shape of the wafer. The edge support portion 53 surrounds the outer periphery of the support frame 54 and is connected to the support frame 54. That is, the support frame 54 extends within the ring-shaped structure enclosed by the edge support portion 53 and is connected to the edge support portion 53.

[0068] The support frame 54 includes multiple support rods 541, which interlock to separate multiple openings 55. The openings 55 are connected to each support rod 541. Preferably, the side profile of the openings 55 is integrally connected to each support rod 541.

[0069] The outer surface of the edge support portion 53 forms an annular side surface 531 of the cage top 50. The cage top 50 has an incident surface 51 and an exit surface 52 arranged opposite to each other along its thickness direction, and the incident surface 51 and the exit surface 52 are connected by the annular side surface 531. The edge support portion 53 can provide rigid support for the outer edge of the support frame 54, and the support frame 54 can provide uniform support for each opening portion 55 on the inner side, thereby improving the deformation resistance of the cage top 50.

[0070] The opening 55 has multiple through holes 551, which penetrate the outer side and the inner side of the top 50 of the cage body, allowing plasma to enter the Faraday cage through the through holes 551 in a direction perpendicular to the top 50 of the cage body. The outer side of the top 50 of the cage body is the surface of the top 50 of the cage body facing the top of the etching chamber, i.e., the incident surface 51; the inner side of the top 50 of the cage body is the surface of the top 50 of the cage body facing the support surface 31, i.e., the exit surface 52. The direction perpendicular to the top 50 of the cage body is the direction perpendicular to the incident surface 51. The interior of the Faraday cage refers to the space between the top 50 of the cage body and the support body 30.

[0071] In some embodiments, the top 50 of the cage is a thin sheet with a thickness of 1.5mm-3.5mm. The incident surface 51 and the exit surface 52 are arranged opposite each other along the thickness direction of the top 50 of the cage. The axis of the through hole 551 is arranged along the thickness direction of the top 50 of the cage, and the cross-section of the through hole 551 is circular or hexagonal. The through hole 551 is used for particles incident through the incident surface 51 to pass through, and the exit surface 52 is used for particles exiting from the through hole 551.

[0072] Under the influence of the first bias power supply 40, charged particles of plasma can enter the through-hole 551 from the incident surface 51 and obtain a more uniform exit direction during the process of passing through the through-hole 551. After passing through the through-hole 551, the charged particles are ejected from the exit surface 52, and the exit angle of the charged particles is usually basically perpendicular to the exit surface 52. The particles ejected from the exit surface 52 can move towards the object to be etched and the carrier 30, and finally bombard the object to be etched on the carrier 30 at a relatively uniform angle.

[0073] In some embodiments, the projection of the top 50 of the cage onto the support surface 31 at least covers the area on the support 30 where the object to be etched is located, to ensure that particles emitted from the exit surface 52 of the top 50 of the cage can completely cover the entire surface of the object to be etched, avoiding abnormal particle incident angles at the edges of the object to be etched due to insufficient size of the top 50 of the cage. Furthermore, the outer edge contour of the top 50 of the cage is similar to the outer edge contour of the object to be etched; for example, when the object to be etched is a circular wafer, the outer edge contour of the top 50 of the cage can be circular.

[0074] The Faraday cage provided in this application has an edge support portion 53 that can support the edge of the entire support frame 54. Since the opening portion 55 is connected to the support frame 54, and the support frame 54 has a dense surface structure, it has higher structural strength than the opening portion 55. It can disperse and offset various stresses as a whole, and avoid stress accumulation on the weaker opening portion 55. It effectively suppresses deformations such as depressions and bending of the opening portion 55. Compared with the traditional large-area unsupported open mesh, the support frame 54 and the edge support portion 53 of the top 50 of the Faraday cage in this application play a role in strengthening the structure, which can improve the rigidity and structural strength of the top 50 of the cage. Even under the conditions of thin walls and large opening ratio, the top 50 of the cage can effectively resist deformation caused by its own weight, thermal stress and airflow impact by relying on the support frame 54, thereby improving the stability of the etching process and extending the service life of the top 50 of the cage.

[0075] In one embodiment, such as Figure 5 As shown, the multiple support rods 541 of the support frame 54 form a mesh structure by interlocking with each other. By adopting a mesh structure, the periphery of each opening 55 can be connected to the support frame 54, thereby improving the support strength of the support frame 54 for each opening 55. The support frame 54 passes through and connects each opening 55. The mesh structure can transfer local stress to the entire support frame 54, avoiding stress concentration in the weak areas of the opening 55. This can significantly improve the overall rigidity of the top 50 of the cage, further prevent deformation, and extend the service life.

[0076] Compared to the overall ring-shaped support frame 54, which is fitted around the outer periphery of a large-area opening 55 and connected to it, this method can only strengthen the structure around the outer periphery of the large-area opening 55 through the support frame 54. The strength of the opening 55 near the central axis is still relatively poor. In contrast, the support frame 54 of this application adopts a mesh structure. The top 50 of the cage is supported by the support frame 54 on the side near the central axis and by the edge support 53 on the side near the outer edge, which greatly improves the deformation resistance to central indentation.

[0077] In one embodiment, the mesh structure supporting the frame 54 can specifically be a rectangular mesh, a rhomboid mesh, a circular mesh, or a hexagonal mesh. Preferably, the mesh structure is honeycomb-shaped. The honeycomb shape uses regular hexagonal mesh, which has stronger bending and torsional resistance compared to other shapes. Furthermore, the interior angles of the hexagons are 120 degrees, with relatively gentle angles and non-sharp corners, preventing stress concentration.

[0078] In one embodiment, the support frame 54 is a solid structure. Compared with a hollow structure, a solid structure can enhance the rigidity of the support frame 54, thereby enhancing the overall deformation resistance of the top 50 of the cage.

[0079] In one embodiment, the top of the cage 50 is integrally formed, and the forming method can be CNC precision machining or 3D printing. The integrally formed top of the cage 50 does not require an assembly process, and the overall structural strength and rigidity are higher.

[0080] Of course, in other embodiments, the edge support portion 53, support frame 54, and opening portion 55 of the cage top 50 can also be separate parts, which are relatively fixed to each other by bonding, welding, or other connection methods. However, this separate method has a connection interface, and its structural strength is lower than that of the integrally formed cage top 50. In the separate embodiment, the edge support portion 53, support frame 54, and opening portion 55 of the cage top 50 can be made of the same material or different materials. The rigidity of the material of the support frame 54 and the edge support portion 53 can be greater than the rigidity of the material of the opening portion 55. Preferably, the materials of the edge support portion 53, support frame 54, and opening portion 55 of the cage top 50 are the same.

[0081] In one embodiment, such as Figure 5 and Figure 6 As shown, the top 50 of the cage has an incident surface 51 and an exit surface 52 arranged opposite to each other. The supporting frame 54 and the opening 55 have flush surfaces on the incident surface 51 and the exit surface 52. That is, the upper surface of the supporting frame 54 and the upper surface of the opening 55 are flush, and the lower surface of the supporting frame 54 and the lower surface of the opening 55 are flush. This makes the electric field on the surface of the top 50 of the cage continuous and avoids the problem of uneven electric field distribution caused by sharp edges on the surface of the top 50 of the cage.

[0082] In one embodiment, the opening ratio of the top 50 of the cage is greater than or equal to 70%, thereby ensuring that charged plasma particles have sufficient space to pass through and improving the etching rate. In another embodiment, the diameter of the through-hole 551 of the opening 55 is smaller than the plasma Debye length, and the plasma Debye length... It can be calculated using the following formula: ,in, The vacuum permittivity, Boltzmann's constant, For electron temperature, Where is the plasma electron density, and e is the elementary charge. Typically, the Debye length is 40 micrometers. By setting the aperture diameter of the aperture 55, the stability of the electric field and the consistency of particle motion direction inside the through-hole 551 can be effectively maintained, thereby improving the etching directionality and uniformity.

[0083] In one embodiment, the top 50 of the cage is made of high-purity aluminum with a purity of not less than 99.999%, and the surface of the high-purity aluminum is anodized to form an anodic aluminum oxide ceramic layer. By using the above-mentioned material for the top 50 of the cage, the high-purity aluminum has fewer impurities and a complete crystal lattice, which can reduce the sputtering rate of the top 50 of the cage. The high density of the anodic aluminum oxide ceramic layer further reduces the sputtering rate of the top 50 of the cage and improves its resistance to plasma corrosion. In some embodiments, the sputtering rate of the top 50 of the cage in the etching process is less than 0.1%, and the lifetime in Cl2 and HBr environments and at 300 degrees Celsius can be greater than 1000 hours.

[0084] During the continuous bombardment of particles by the top 50 of the cage, the top 50 absorbs some of the particles' kinetic energy and converts it into heat energy. To prevent thermal deformation of the top 50 of the cage, such as... Figure 7 and Figure 8 As shown, at least a portion of the supporting frame 54 and / or at least a portion of the edge support portion 53 form a hollow structure inside. The hollow structure includes an inlet and an outlet for introducing a non-conductive coolant. The coolant is preferably a non-conductive liquid, i.e., a dielectric coolant, to prevent interference with the electric field distribution; for example, a fluorinated liquid, such as a perfluoropolyether, can be used.

[0085] The edge support 53 and the support frame 54 can form a reinforced support structure, improve the strength of the top of the cage 50, and also allow coolant to be introduced into the interior. The coolant can quickly absorb and remove the heat accumulated by the top of the cage 50 during bombardment, thereby significantly reducing the overall operating temperature of the top of the cage 50, avoiding heat accumulation in the top of the cage 50, thus suppressing thermal deformation of the top of the cage 50, and preventing deformation of the through hole 551 from affecting the etching angle.

[0086] In one embodiment, such as Figure 7 As shown, both the interior of the edge support portion 53 and the interior of the support frame 54 form hollow structures. The hollow structure of the support frame 54 forms a first channel 542, and the hollow structure of the edge support portion 53 forms a second channel 532. The second channel 532 is connected to the first channel 542 and has an inlet and an outlet. The number of inlets and outlets can be at least one. The inlet is used to introduce coolant, and the outlet is used to allow coolant to flow out. Thus, coolant can enter the second channel 532 from the inlet and flow within the second channel 532 to cool the edge support portion 53. Since the second channel 532 is connected to the first channel 542, coolant can flow from the second channel 532 into the first channel 542, allowing the coolant to cool the support frame 54 and the opening portion 55. This allows the coolant to flow to more locations inside the cage top 50, improving the heat dissipation capacity of the cage top 50.

[0087] In one embodiment, such as Figure 8 As shown, each of the first pillars 62 is provided with an inlet channel 621 and an outlet channel 622, meaning that the inlet channel 621 and the outlet channel 622 are located in different first pillars 62. The inlet is connected to the inlet channel 621, and the outlet is connected to the outlet channel 622. The inlet channel 621 is used to allow coolant to enter the inlet, and the outlet channel 622 is used to allow coolant to flow out of the outlet. In this embodiment, the first pillar 62 can simultaneously serve as both a support and a coolant delivery function, simplifying the structure within the etching cavity 10 and reducing the risk of leakage. When the first pillar 62 needs to accommodate wires simultaneously, the inlet channel 621 and the space for accommodating the wires are two independent spaces, and the outlet channel 622 and the space for accommodating the wires are two independent spaces.

[0088] Further, in one embodiment, one end of the liquid inlet channel 621 is connected to the liquid inlet, and the other end of the liquid inlet channel 621 is located outside the etching chamber 10 and connected to the water outlet of the water chiller. One end of the liquid outlet channel 622 is connected to the liquid outlet, and the other end of the liquid outlet channel 622 is located outside the etching chamber 10 and connected to the water inlet of the water chiller. After being pressurized by the water chiller, the coolant enters the top 50 of the cage through the liquid inlet channel 621 and the liquid inlet, flows inside the support frame 54 and the edge support 53, and continuously absorbs the heat generated by the plasma bombardment. Then, the coolant flows back to the water chiller through the liquid outlet and the liquid outlet channel 622, is cooled by the water chiller, and continues to circulate. In other embodiments, the liquid inlet channel 621 can also be connected to the coolant pool, and the coolant in the coolant pool can be pumped into the liquid inlet channel 621. The liquid outlet channel 622 can be connected to the waste liquid pool to remove the coolant after absorbing heat.

[0089] In one embodiment, the edge support 53 is an annular structure, and the shortest circumferential distance between the inlet and outlet on the annular structure is greater than one-quarter of the circumference of the annular structure. In some embodiments, the shortest circumferential distance between the inlet and outlet on the annulus is one-third of the circumference of the annulus. By limiting the spacing between the inlet and outlet on the circumferential direction of the edge support 53, the circulation path of the coolant in the second channel 532 can be effectively extended, allowing the coolant to flow fully on the top 50 of the cage, thereby improving heat exchange time and heat dissipation efficiency.

[0090] Preferably, such as Figure 7As shown, the outer edge of the first channel 542 has multiple branch outlets 5421, which are spaced apart circumferentially along the edge support 53. Each branch outlet 5421 is connected to the second channel 532, allowing more coolant from the second channel 532 to enter the first channel 542 from various circumferential directions through the branch outlets 5421, making it easier for coolant from the second channel 532 to enter the first channel 542. By setting parameters such as the output pressure and flow rate of the water chiller, the coolant can enter the entire cooling circuit with sufficient pressure and flow rate, ensuring that both the first channel 542 and the second channel 532 are completely filled with coolant.

[0091] like Figure 9 and Figure 10 As shown, the top 50 of the cage includes a mesh-shaped first cage 56 and a mesh-shaped second cage 57. Preferably, both the first cage 56 and the second cage 57 are conductive, meaning they are made of a conductive material, preferably a metal. The first cage 56 has a plurality of first through holes 561 penetrating the outer side and the inner side of the first cage 56. Specifically, the first cage 56 has a first incident surface 562 and a first exit surface 563 arranged opposite to each other. The outer side of the first cage 56 refers to the surface of the first cage 56 facing the top of the etching cavity, i.e., the first incident surface 562, and the inner side of the first cage 56 refers to the surface of the first cage 56 facing the bearing surface 31, i.e., the first exit surface 563. In some embodiments, the first cage 56 is a thin sheet with a thickness of 1.5mm-3.5mm. The first incident surface 562 and the first exit surface 563 are arranged opposite each other along the thickness direction of the first cage 56. The axis of the first through hole 561 is arranged along the thickness direction of the first cage 56, and the cross-section of the first through hole 561 can be circular or hexagonal. The first through hole 561 is used for particles incident through the first incident surface 562 to pass through, and the first exit surface 563 is used for particles exiting from the first through hole 561.

[0092] The second cage 57 is provided with a plurality of second through holes 571 penetrating the outer side and the inner side of the second cage 57. Specifically, the second cage 57 has a second incident surface 572 and a second exit surface 573 arranged opposite to each other. The outer side of the second cage 57 refers to the surface of the second cage 57 facing the top of the etching cavity, i.e., the second incident surface 572, and the inner side of the second cage 57 refers to the surface of the second cage 57 facing the bearing surface 31, i.e., the second exit surface 573. In some embodiments, the second cage 57 is in the form of a thin sheet with a thickness of 1.5mm-3.5mm. The second incident surface 572 and the second exit surface 573 are arranged opposite to each other along the thickness direction of the second cage 57. The axis of the second through hole 571 is arranged along the thickness direction of the second cage 57, and the cross-section of the second through hole 571 can be circular or hexagonal. The second through-hole 571 is used for particles incident through the second incident surface 572 to pass through, and the second exit surface 573 is used for particles exiting from the second through-hole 571.

[0093] Preferably, the first cage 56 and the second cage 57 have the same thickness, and the size and shape of the outer contour of the first cage 56 are the same as the size and shape of the outer contour of the second cage 57.

[0094] The first cage 56 and the second cage 57 are disposed opposite to each other with a gap 58 between them. The gap 58 communicates with the interior of the etching chamber 10 so that the process gas of the etching chamber 10 can enter the gap 58. Specifically, the gap 58 communicates with the first through hole 561 and the second through hole 571. Specifically, the first exit surface 563 is disposed facing the second incident surface 572. The first cage 56 and the second cage 57 are spaced apart along the thickness direction of the first cage 56. The first exit surface 563 and the second incident surface 572 are disposed opposite to each other along the thickness direction of the first cage 56. Preferably, the first incident surface 562, the first exit surface 563, the second incident surface 572, and the second exit surface 573 are all disposed parallel to each other. The second cage 57 is disposed closer to the carrier 30 relative to the first cage 56.

[0095] When the gas delivery assembly delivers process gas into the etching chamber 10, the process gas in the etching chamber 10 can enter the gap 58 through the first through-hole 561 and the second through-hole 571, so that the gap 58 can contain the process gas. The first through-hole 561 is used to allow plasma to enter the gap 58 in a direction perpendicular to the first cage 56, which is the same direction perpendicular to the first incident surface 562. The second through-hole 571 is used to allow particles in the gap 58 to pass through. Specifically, under the action of induction coil 212, a small portion of the process gas can be initially ionized into plasma in the etching cavity. Both the process gas and plasma in the etching cavity can enter the gap 58. Compared to the etching cavity, the gap 58 is a narrow space. After the process gas and plasma in the etching cavity enter the gap 58, the free movement path of the process gas particles in the gap 58 is shorter. Compared to the process gas in the etching cavity, the collision frequency between process gas particles in the gap 58 can be significantly increased. The high-frequency collisions between particles can promote the ionization of more process gas particles, thereby generating more plasma and enhancing the plasma density in the gap 58. Finally, the particles in the gap 58 are ejected from the second through hole 571 to the etching area, increasing the density of plasma emitted from the second cage 57.

[0096] In the plasma etching apparatus, the second cage 57 is disposed at intervals above the carrier 30, and the second exit surface 573 is disposed facing the carrier 30 so that the particles emitted through the second exit surface 573 can move toward the object to be etched and the carrier 30, and the exit angle of the charged particles emitted from the second exit surface 573 is substantially perpendicular to the second exit surface 573. The first cage 56 is located on the side of the second cage 57 away from the carrier 30.

[0097] like Figure 10 and Figure 11 As shown, in one embodiment, the top 50 of the cage body further includes an insulating connection portion 59, which is disposed within the gap 58. One end of the insulating connection portion 59 is connected to the first cage body 56, and the other end is connected to the second cage body 57. Specifically, both ends of the insulating connection portion 59 can be fixedly connected to the first exit surface 563 and the second incident surface 572, respectively. The insulating connection portion 59 can be used to maintain the spacing of the gap 58, prevent changes in the spacing of the gap 58, and connect the first cage body 56 and the second cage body 57 into one unit, ensuring the structural stability of the top 50 of the cage body. The insulating connection portion 59 can achieve electrical isolation between the first cage body 56 and the second cage body 57, prevent mutual potential interference between them, and prevent the formation of an electric arc in the gap 58. The insulating connection portion 59 can be made of materials such as alumina ceramic or yttrium oxide ceramic. The insulating connection portion 59 can be connected to the first cage body 56 and the second cage body 57 by adhesive bonding.

[0098] The insulating connection portion 59 may be annular, for example. In some embodiments, there are multiple insulating connections 59, which are arranged separately on the edges of the first cage 56 and the second cage 57, and are spaced apart along the circumferential direction of the gap 58. An opening is formed between the multiple insulating connections 59, and the outer periphery of the gap 58 communicates with the etching chamber 10 through the opening, which allows the process gas in the etching chamber 10 to enter the gap 58.

[0099] In one embodiment, the spacing of the gaps 58 is 'a', where 10mm ≤ a ≤ 20mm. Preferably, the spacing of the gaps 58 is equal at all points. By limiting the range of the spacing, the residence time of particles within the gaps 58 can be effectively extended, allowing the particles to fully collide and ionize with the process gas within the gaps 58. This avoids problems such as insufficient process gas due to too small a spacing of the gaps 58 or a decreased collision probability due to too large a spacing of the gaps 58.

[0100] In one embodiment, the second cage 57 is positioned closer to the carrier 30 than the first cage 56. The aperture ratio of the first cage 56 is less than or equal to that of the second cage 57. The aperture ratio is the proportion of the area of ​​the holes to the area of ​​the entire cage. The larger the aperture ratio, the better the uniformity of the emitted plasma. This results in the uniformity of the plasma emitted from the second cage 57 being greater than that of the plasma emitted from the first cage 56, thus making the uniformity of the plasma reaching the carrier 30 stronger.

[0101] Furthermore, in one embodiment, such as Figure 12 As shown, the diameter of the first through-hole 561 is larger than that of the second through-hole 571, and the density of the first through-hole 561 is less than that of the second through-hole 571. The density of through-holes is the number of through-holes per unit area. Since the diameter of the first through-hole 561 is larger than that of the second through-hole 571, the difference in diameter between the two through-holes can prolong the residence time of particles in the gap 58, increasing the probability of more collisions between particles in the gap 58. More collisions can excite more ionization of process gas, thereby enhancing the plasma density in the gap 58. In addition, the diameter of the second through-hole 571 is smaller and the distribution is denser, which is beneficial to improving the uniformity of the plasma emitted from the second through-hole 571.

[0102] In another embodiment, the aperture of the first through hole 561 is equal to the aperture of the second through hole 571, and the density of the first through hole 561 is less than or equal to the density of the second through hole 571. Similarly, the opening ratio of the first cage 56 can be less than or equal to the opening ratio of the second cage 57, thereby improving the uniformity of the plasma emitted from the second cage 57.

[0103] In one embodiment, both the first cage 56 and the second cage 57 may include an edge support, a support frame, and an opening. The specific structure can be referred to the description of the structure and cooperation relationship of the edge support, the support frame, and the opening in the previous text, and will not be repeated here.

[0104] In one embodiment, such as Figure 13 As shown, when the top 50 of the cage is mounted above the carrier 30 via the tilt angle adjustment bracket 60, the plasma etching apparatus also includes an adjustable bias power supply 70, a sheath potential monitoring unit, and a control unit 80.

[0105] An adjustable bias power supply 70 is electrically connected to the top of the cage 50 to provide bias voltage to the top of the cage 50. The adjustable bias power supply 70 can be a DC power supply, an RF power supply, or a composite power supply of DC and RF, and its output voltage amplitude and / or frequency can be adjusted according to a control signal. When the adjustable bias power supply 70 applies bias voltage to the top of the cage 50, the top of the cage 50 acts as an electrode, and a sheath is formed in the plasma near its surface. Since the plane of the top of the cage 50 is inclined relative to the bearing surface 31, the equipotential surfaces in the sheath also tilt accordingly, forming an asymmetric electric field. Under the action of this asymmetric electric field, positive ions are accelerated along the direction of the electric field, and their incident direction deviates from the normal direction of the bearing surface 31, that is, deviates from the vertical direction, thereby achieving a deflection of the ion incident angle. The specific shape of the asymmetric electric field (including the degree of inclination of the equipotential surfaces and the spatial distribution of the electric field) is affected by both the tilt angle of the top of the cage 50 and the magnitude of the applied bias voltage. The tilt angle of the top 50° of the cage determines the basic direction of the angular deflection, while the magnitude of the applied bias voltage affects the sheath thickness and electric field strength, which in turn affects the acceleration energy and deflection degree of the ions.

[0106] The sheath potential monitoring unit is used to detect the sheath potential at at least two monitoring positions within the region between the top 50 of the cage and the supporting surface 31. The monitoring positions are distributed along the direction in which the top 50 of the cage is inclined relative to the supporting surface 31. The inclination direction of the top 50 of the cage relative to the supporting surface 31 refers to the direction (or the opposite direction) in the space between the top 50 of the cage and the supporting surface 31 from the side with the smaller distance to the side with the larger distance. In one embodiment, the inclination direction refers to the direction of the line connecting the point with the smallest distance and the point with the largest distance between the top 50 of the cage and the supporting surface 31. Along the inclination direction, the distance between the top 50 of the cage and the supporting surface 31 changes continuously, therefore the sheath thickness and electric field distribution at different positions also change accordingly. The different distribution points of each monitoring position along the inclination direction can obtain potential information reflecting the characteristics of the change in the sheath electric field along that direction.

[0107] Each monitoring position has a different height relative to the bearing surface 31. Because the top 50 of the cage is inclined relative to the bearing surface 31, the vertical distance (i.e., height) between the lower surface of the top 50 of the cage and the bearing surface 31 varies at different positions along the inclination direction. The monitoring positions can be set at a specific height between the top 50 of the cage and the bearing surface 31, for example, a position near the lower surface of the top 50, a position near the bearing surface 31, or a position at a certain height in between. By detecting the sheath potential at at least two monitoring positions with a height difference, the spatial distribution information of the potential in the sheath along the inclination direction can be obtained, thus reflecting the actual state of the asymmetric electric field.

[0108] The sheath potential monitoring unit can be implemented using a probe-based voltage detection device. The detection ends of the probes are respectively set at each monitoring position to obtain the local plasma potential at each position. Each probe is in direct contact or capacitively coupled to the plasma at its location, converting the plasma potential into a measurable electrical signal output.

[0109] The control unit 80 is connected to the sheath potential monitoring unit and the adjustable bias power supply 70. The control unit 80 can be a controller based on a microprocessor (MCU), digital signal processor (DSP), field-programmable gate array (FPGA), or industrial control computer, and has functions such as signal acquisition, data processing, control algorithm calculation, and instruction output.

[0110] The control unit 80 determines the target bias voltage based on the target incident angle. The target incident angle is the desired angle at which ions bombard the surface of the object to be etched, as set by the process, and is usually expressed as the angle between the ion incident direction and the normal direction of the bearing surface 31. The target bias voltage is the base bias voltage value that should be applied to the top 50 of the cage, determined based on the target incident angle. The correspondence between the target incident angle and the target bias voltage can be obtained through pre-test calibration or simulation calculation based on a physical model. For example, a calibration curve or lookup table of bias voltage value versus incident angle at different tilt angles can be established and stored in the control unit 80. The control unit 80 queries the corresponding target bias voltage based on the target incident angle and controls the adjustable bias power supply 70 to provide the target bias voltage to the top 50 of the cage.

[0111] During the etching process, the control unit 80 receives the sheath potential at at least two monitoring locations output by the sheath potential monitoring unit. These potential signals reflect the actual distribution of the sheath electric field under the current state. The control unit 80 determines the potential difference based on a preset reference and the sheath potential at each monitoring location. The preset reference is a reference value or reference point used to measure whether the sheath potential distribution meets the target requirements. It can be a preset fixed potential value, or the potential at a certain monitoring location can be used as the reference value, or it can be a target potential value calculated based on the target incident angle. The control unit 80 compares the sheath potential at each monitoring location with the preset reference to obtain the potential difference characterizing the deviation between the current electric field distribution and the target state.

[0112] The control unit 80 generates a bias correction amount based on the potential difference. The bias correction amount reflects the adjustment required to eliminate the deviation between the current electric field distribution and the target state, restoring the ion incident angle to the target incident angle. The generation of the bias correction amount can be achieved using various control algorithms, such as proportional-integral-derivative (PID) control, fuzzy control, and model predictive control. After generating the bias correction amount, the control unit 80 controls the adjustable bias power supply 70 to add the bias correction amount to the target bias, that is, the total bias voltage after adding the target bias voltage and the bias correction amount is output to the top of the cage 50.

[0113] After the bias correction is applied, the bias applied to the top 50 of the cage changes, and the electric field distribution of the sheath below it is adjusted accordingly, thereby dynamically compensating for the distortion of the sheath electric field caused by factors such as plasma density fluctuations, electron temperature changes, cage thermal deformation, and process gas pressure changes. Through this closed-loop feedback adjustment process, ions in the plasma are incident at the target incident angle onto the surface of the object to be etched on the bearing surface 31, achieving real-time stable control of the tilt etching angle.

[0114] In some embodiments, the sheath potential monitoring unit includes at least two Langmuir probes arranged in a direction inclined relative to the bearing surface 31 along the top 50 of the cage, with each Langmuir probe corresponding to a monitoring position.

[0115] The Langmuir probe is a mature detection device for plasma diagnostics. Its working principle involves exposing the tip of a thin metal wire (typically tungsten, molybdenum, or platinum) to the plasma. By applying a scanning voltage to the probe and measuring the collected current, parameters such as the local plasma potential, electron temperature, and ion density at the probe's location can be obtained. In this embodiment, the Langmuir probe is primarily used to detect the sheath potential, i.e., the local plasma potential, at its monitoring location. The Langmuir probes are arranged sequentially along the direction inclined from the top 50 of the cage relative to the supporting surface 31, with the detection end of each probe located at a corresponding monitoring position. Since each monitoring position has a different height along this inclined direction, the potential detected by each Langmuir probe can reflect the spatial distribution characteristics of the sheath potential along this direction.

[0116] To facilitate the accurate detection of the sheath potential at at least two monitoring positions in the area between the top 50 of the cage and the bearing surface 31 by the sheath potential monitoring unit, the top 50 of the cage is insulated and isolated into multiple parts along the inclined direction, and each part is equipped with a Langmuir probe to detect the sheath potential at a corresponding monitoring position.

[0117] like Figure 14 As shown, the top 50 of the Faraday cage is insulated and separated into a first part and a second part. Figure 14 In the scenario shown, the top 50 of the cage can be insulated and isolated into a first part and a second part along a direction inclined relative to the bearing surface 31. That is, it can be divided based on the distance between the top 50 of the cage and the bearing surface 31, such as dividing the top 50 of the cage into a smaller half and a larger half. The insulation between the first part and the second part refers to setting an insulating partition structure on the top 50 of the cage, dividing the originally electrically conductive top 50 of the cage into two mutually electrically insulated parts. The insulating partition structure can be an insulating strip, an insulating groove, or an insulating filler, etc., so that there is no direct electrical conduction between the first part and the second part. The first part and the second part are respectively connected to an adjustable bias power supply 70, meaning that each part can independently receive the bias voltage provided by the adjustable bias power supply 70, and the bias voltage values ​​can be the same or different.

[0118] Correspondingly, such as Figure 2As shown, the sheath potential monitoring unit can be equipped with two Langmuir probes, namely a first Langmuir probe 91 and a second Langmuir probe 92. The detection end of the first Langmuir probe 91 is located at a first monitoring position below the first part, and is used to detect the sheath potential in the region below the first part; the detection end of the second Langmuir probe 92 is located at a second monitoring position below the second part, and is used to detect the sheath potential in the region below the second part. The potential difference between the two directly reflects the uniformity of the asymmetric electric field along the tilt direction. By transmitting the potential signals collected by each Langmuir probe to the control unit 80 in real time, multi-point synchronous monitoring of the sheath potential can be achieved, providing input data for subsequent potential difference calculation and bias correction generation.

[0119] The top 50 of the cage is insulated and isolated into two independently powered sections, each equipped with a Langmuir probe for potential monitoring. On one hand, the two sections can be biased independently. When the electric field below one section needs adjustment, only the bias voltage of that section needs adjustment, without affecting the state of the other section, achieving spatial selectivity in electric field adjustment. On the other hand, the sheath potential below each section is independently detected by the corresponding Langmuir probe, reflecting the actual state of the electric field below each section and providing the control unit 80 with regional electric field distribution information. This structure is particularly suitable for compensating for sheath asymmetry caused by cage tilt: when a potential deviation from the target value is detected on one side, the bias voltage of the corresponding cage section on that side can be adjusted accordingly, thereby achieving precise local electric field correction.

[0120] like Figure 2 As shown, the first part is located at a higher position relative to the bearing surface 31, and the second part is located at a lower position relative to the bearing surface 31. "Higher position relative to the bearing surface 31" refers to the side with a larger vertical distance between the first part and the bearing surface 31, and "lower position" refers to the side with a smaller vertical distance between the second part and the bearing surface 31. In other words, the first part is located at the higher end in the inclined direction of the top 50 of the cage, and the second part is located at the lower end.

[0121] The control unit 80 uses the potential detected by the first Langmuir probe 91 as a preset reference. The first Langmuir probe 91 detects the sheath potential below the first part (i.e., the higher part). In the configuration of the tilted Faraday cage, the sheath thickness at the higher part is larger, the electric field distribution is relatively uniform, and its potential value is relatively stable, thus making it suitable as a potential reference. The control unit 80 uses the potential detected by the second Langmuir probe 92 as the adjustment object and calculates the potential difference between the potential detected by the second Langmuir probe 92 and the preset reference (i.e., the potential detected by the first Langmuir probe 91).

[0122] When the potential difference is not zero, it indicates a deviation between the sheath potential at the lower location and the reference potential at the higher location, and the shape of the asymmetric electric field deviates from the ideal state. The control unit 80 generates a bias correction amount based on this potential difference and controls the adjustable bias power supply 70 to superimpose the bias correction amount onto the target bias of the second part. By adjusting the bias of the lower cage portion (the second part), the electric field strength in the lower sheath is changed, making the potential detected by the second Langmuir probe 92 approach the potential detected by the first Langmuir probe 91. When the two potentials are equal, it indicates that the sheath potential distribution along the tilt direction has reached the target state, and the ion incident angle is stable at the target incident angle. The core control of the control unit 80 is to use the stable potential at the higher location as an anchor point and only adjust the bias at the lower location to eliminate the potential difference. The control logic is simple, the response speed is fast, and it is suitable for most tilt etching applications.

[0123] In addition to performing dynamic bias correction, the control unit 80 also performs coarse adjustment control, implementing a two-level control strategy. Specifically, when the potential difference exceeds a preset threshold, the control unit 80 controls the tilt angle adjustment bracket 60 to adjust the included angle to reduce the potential difference; after the included angle adjustment is completed, the target bias is redefined based on the adjusted included angle, and then a bias correction amount is generated based on the potential difference. The control unit 80 then controls the adjustable bias power supply 70 to add the bias correction amount to the redefined target bias.

[0124] Coarse Adjustment Stage: When the control unit 80 determines that the potential difference detected by the sheath potential monitoring unit exceeds the preset threshold, it indicates that the current asymmetric state of the sheath electric field has significantly deviated from the target state. Electrical bias correction alone may not be sufficient to adjust the angle deviation to an acceptable range, or the required bias correction may be too large, exceeding the reasonable output range of the adjustable bias power supply 70 or the allowable range of the plasma process window. At this time, the control unit 80 controls the tilt angle adjustment frame 60 to adjust the angle between the plane where the top 50 of the cage is located and the bearing surface 31, in order to reduce the potential difference from the source. Specifically, by adjusting the tilt angle of the top 50 of the cage, the geometric relationship between the top 50 of the cage and the bearing surface 31 is changed, directly altering the asymmetric shape of the sheath electric field, causing the sheath potential distribution along the tilt direction to tend towards the target state (i.e., the potential at each monitoring position tends to be consistent).

[0125] Fine-tuning stage: After the tilt angle adjustment frame 60 completes the angle adjustment, the control unit 80 redetermines the target bias voltage based on the new angle. Since the angle has changed, the corresponding target bias voltage value also needs to be recalculated or obtained from a table based on the new geometric relationship. Then, the control unit 80 generates a bias voltage correction amount based on the potential difference detected by the current sheath potential monitoring unit, and controls the adjustable bias power supply 70 to add the bias voltage correction amount to the newly determined target bias voltage for fine electrical compensation.

[0126] Mechanical coarse adjustment addresses large angular deviations by modifying the physical orientation of the Faraday cage, offering a wide response range but relatively limited adjustment precision and speed. Electrical fine adjustment, on the other hand, addresses small, rapidly changing angular fluctuations through dynamic bias compensation, boasting fast response and high adjustment precision. The combination of both provides coverage of a broad angular adjustment range while ensuring high-precision, real-time stable control. Furthermore, the presence of mechanical coarse adjustment prevents electrical fine adjustment from operating under extreme bias conditions for extended periods, thus extending the lifespan of the adjustable bias power supply 70 and the Faraday cage, and maintaining a reasonable process window.

[0127] Figure 15 This is a flowchart illustrating a plasma etching angle control method provided in one embodiment of this application. Figure 15 As shown, the plasma etching angle control method provided in this embodiment is executed by the control unit in any of the above embodiments to dynamically adjust the bias voltage applied to the top of the cage, thereby compensating in real time for the sheath electric field distortion caused by factors such as plasma density fluctuations, electron temperature changes, cage thermal deformation, or process gas pressure fluctuations, so as to stabilize the ion incident angle at the target incident angle. This control method specifically includes the following steps:

[0128] Step S601: Obtain the target incident angle and determine the target bias applied to the top of the Faraday cage based on the target incident angle; wherein the top of the cage is spaced apart from the bearing surface used to support the object to be etched, and the plane where the top of the cage is located has an angle with the bearing surface.

[0129] The target incident angle is the desired angle at which ions bombard the surface of the object to be etched. It is usually expressed as the angle between the ion incident direction and the normal direction of the bearing surface, and its value is determined by the structure of the device to be processed.

[0130] The target incident angle can be obtained through human-machine interface input, process formula import, or upper computer communication.

[0131] Given the known angle between the plane containing the top of the cage and the bearing surface, a correspondence is established between the target incident angle and the applied bias voltage. Based on this relationship, the required basic bias voltage value can be determined. This correspondence can be obtained through pre-calibrated experiments: by varying the applied bias voltage at different tilt angles, measuring the actual ion incident angle, and establishing a "bias voltage-incident angle" calibration curve or lookup table, which is then stored in the system. During process execution, the corresponding target bias voltage can be determined by querying the calibration data based on the currently set target incident angle. The target bias voltage is the initial bias voltage applied to the top of the cage, used to establish the basic asymmetric electric field required to achieve the target incident angle.

[0132] Step S602: Obtain the sheath potential at at least two monitoring locations in the region between the top of the cage and the bearing surface, along the direction in which the top of the cage is inclined relative to the bearing surface.

[0133] The region between the top of the cage and the supporting surface is the core space for plasma sheath formation and ion acceleration, and its electric field distribution directly determines the acceleration direction and incident angle of the ions. The sheath potential in this region is obtained by deploying at least two monitoring probes. The more monitoring points, the more detailed the description of the sheath potential distribution along the tilt direction.

[0134] Meanwhile, the monitoring positions are distributed along the direction in which the top of the cage is inclined relative to the bearing surface. This inclination direction refers to the direction from the side where the distance between the top of the cage and the bearing surface is smaller to the side where the distance is larger. Along this direction, the distance between the top of the cage and the bearing surface changes continuously, and the sheath thickness and electric field strength also change accordingly. The monitoring positions have different distribution locations in this direction, thus enabling the detection of different potential values ​​that reflect the trend of electric field variation along this direction.

[0135] The sheath potential can be obtained using potential detection devices, such as Langmuir probes, placed at various monitoring locations. Each detection device converts the local plasma potential at its location into an electrical signal, which is then transmitted to the control device executing the method. The potential signal can be acquired continuously or discretely at a preset sampling rate (e.g., 1 kHz) to track the dynamic changes in the sheath potential during etching in real time.

[0136] Step S603: Determine the potential difference based on the preset benchmark and the sheath potential at each monitoring location.

[0137] A preset benchmark is a reference standard used to measure whether the current sheath potential distribution meets the target requirements. The preset benchmark can be selected in several ways: for example, the potential detected at a specific monitoring location can be used as the benchmark value. This specific monitoring location is usually selected at a location where the potential is relatively stable and less susceptible to interference (such as a high point in the inclined direction); or, the preset benchmark can be a pre-set target potential value, which can be determined through theoretical calculation or experimental calibration based on the target incident angle, plasma process parameters, etc.

[0138] When determining the potential difference, the sheath potential at each monitoring location obtained in step S602 is compared with a preset benchmark, and the difference is calculated. When the potential at each monitoring location is consistent with the preset benchmark, the potential difference is zero, indicating that the current sheath potential distribution is in the target state; when there is a deviation, the potential difference is not zero, and the magnitude and sign of the deviation reflect the degree and direction of the current sheath electric field deviating from the target state. The potential difference provides an error input signal for the subsequent generation of the bias correction.

[0139] Step S604: Generate bias correction amount based on potential difference.

[0140] After determining the sheath potential difference at each monitoring location, the potential difference is used as input to generate a bias correction value through a preset control algorithm. This value is used to adjust the incremental value of the bias applied to the top of the cage. Its function is to adjust the sheath electric field by changing the bias, eliminate the potential difference, and restore the sheath potential distribution to the target state.

[0141] Step S605: The target bias and the bias correction are superimposed and applied to the top of the cage so that the ions in the plasma are incident at the target incident angle.

[0142] After determining the bias correction amount, it is superimposed on the target bias determined in step S601, i.e., the two are algebraically added together to obtain the adjusted total bias value. When the bias correction amount is positive, the total bias is higher than the target bias; when the bias correction amount is negative, the total bias is lower than the target bias. The superimposed total bias is then applied to the top of the cage. The change in bias adjusts the sheath thickness and equipotential surface morphology, and the electric field distribution of the sheath below the top of the cage changes accordingly, i.e., the spatial distribution of the asymmetric electric field changes. The direction and magnitude of this adjustment match the bias correction amount, aiming to compensate for the electric field distortion caused by various factors (such as plasma density fluctuations, electron temperature changes, cage thermal deformation, process gas pressure fluctuations, etc.), so that the sheath potential distribution approaches the target state.

[0143] When the sheath potential distribution returns to the target state, the shape of the asymmetric electric field matches the target incident angle, and the acceleration direction of the ions under the action of this electric field is aligned with the target incident angle. Finally, the ions in the plasma bombard the object to be etched on the bearing surface at the target incident angle, achieving closed-loop stable control of the tilt etching angle.

[0144] The plasma etching angle control method provided in this embodiment obtains the target incident angle and determines the basic target bias voltage applied to the tilted Faraday cage accordingly. During the etching process, the sheath potential at multiple locations along the tilt direction between the top of the cage and the supporting surface is detected in real time. The potential difference is calculated based on a preset benchmark, and a bias voltage correction is generated accordingly. The target bias voltage and the bias voltage correction are dynamically superimposed and applied to the top of the cage, forming a closed-loop feedback regulation of the sheath electric field. This method can automatically detect the deviation of the electric field state and correct the applied bias voltage in real time when the electric field of the sheath is distorted due to fluctuations in process conditions such as plasma density, temperature, and gas pressure, as well as thermal deformation of the cage. This ensures that the ion incident angle remains stable at the target value, significantly improving the angle control accuracy, anti-interference capability, and batch repeatability of the tilted etching process, providing a reliable control means for high-precision micro-nano structure fabrication.

[0145] In some embodiments, the key step S604, generating the bias correction amount based on the potential difference, can be achieved by using the potential difference as an error signal and performing PID calculations on the error signal to obtain the bias correction amount. This method has simple and direct control logic, does not require intermediate conversion from potential difference to angle, has low computational overhead, and is suitable for real-time control scenarios with extremely high response speed requirements.

[0146] In the case of two Langmuir probes, with the potential detected by the first Langmuir probe (located at a higher position relative to the bearing surface) as the preset reference and the potential detected by the second Langmuir probe (located at a lower position relative to the bearing surface) as the adjustment target, the error signal... for:

[0147]

[0148] in, This represents the potential detected by the first Langmuir probe at the current moment. This represents the potential detected by the second Langmuir probe at the current moment. When the two potentials are equal, This indicates that the sheath potential is uniformly distributed along the tilt direction, and the ion incident angle reaches the target state; when When the sign and magnitude of the value reflect the degree and direction of the low-side potential deviating from the reference, the value of the value is positive or negative.

[0149] In the digital control implementation, the control unit samples the sheath potential with a fixed sampling period T_s (e.g., 1ms, corresponding to a 1kHz sampling rate) and uses an incremental PID algorithm to calculate the bias correction. A single error signal is used... For example, the bias correction at the k-th sampling time. Determined according to the following formula:

[0150]

[0151] in, The potential difference at the current sampling time. and These are the potential differences at the previous and the two previous sampling times, respectively; These are the proportional coefficient, integral coefficient, and derivative coefficient, respectively, which are determined based on actual process adjustments.

[0152] The total bias voltage applied to the top of the cage (or the corresponding insulating part) at the current moment is:

[0153]

[0154] in, The target bias is applied.

[0155] This incremental PID algorithm only needs to store the three most recent error values, resulting in low computational complexity. Furthermore, its incremental output facilitates smooth adjustment and fault protection. When arcing, overcurrent, or a momentary exceedance of the potential difference limit occurs, it can directly... Clamp or zero out to quickly cut off abnormal bias voltage.

[0156] In other embodiments, step S604 generates a bias correction amount based on the potential difference, and also determines the angle deviation of the ion incident angle based on the potential difference, performs PID calculation on the angle deviation, and obtains the bias correction amount. This method directly targets the control objective to the final process indicator of the ion incident angle, making the physical meaning clearer, the tuning of the PID parameters more intuitive, and adapting to the nonlinear sheath characteristics through the electric field-angle conversion coefficient.

[0157] The specific implementation of this method first requires calculating the sheath potential gradient based on the potential difference and the distance between at least two monitoring positions along the tilt direction.

[0158] For the case with two Langmuir probes, the two monitoring positions are located at a higher and lower position respectively along the direction of inclination of the top of the cage relative to the bearing surface, and their distance is denoted by d. The distance d refers to the projected distance between the two monitoring positions in the inclination direction. The sheath potential gradient is calculated using differential calculus:

[0159]

[0160] in, This refers to the potential detected by the probe at a higher position. This represents the potential detected by the probe at a lower elevation. The physical meaning of this gradient is the rate of change of the sheath potential along the tilt direction, directly reflecting the degree of tilt of the asymmetric electric field.

[0161] Then, based on the pre-calibrated electric field-angle conversion coefficient, the difference between the calculated sheath potential gradient and the preset target sheath potential gradient is converted into an angle deviation.

[0162] The pre-calibrated electric field-angle conversion coefficient K is a parameter characterizing the mapping relationship between the change in sheath potential gradient and the change in ion incident angle, and can be obtained through experimental calibration or simulation calculation. The preset target sheath potential gradient... , is the ideal gradient value when the ion incident angle equals the target incident angle, and is predetermined based on the target incident angle and the cage's geometric parameters. Angle deviation It can be calculated using the following formula:

[0163]

[0164] in, This is the calculated current measured sheath potential gradient. When the measured gradient equals the target gradient, the angle deviation... A value of zero indicates that the current ion incident angle is equal to the target incident angle; The sign and magnitude of the value directly reflect the direction and magnitude of the incident angle deviating from the target value.

[0165] Finally, PID calculations are performed on the angle deviation to obtain the bias correction amount.

[0166] Obtaining angle deviation After that, with The error signal is used for PID calculation to generate the bias correction. The continuous form of the PID calculation is:

[0167]

[0168] in, These are the proportionality coefficient, integral coefficient, and differential coefficient, respectively. Proportional term This represents a correction amount generated proportionally to the magnitude of the current angular deviation; the larger the deviation, the stronger the correction. (Integral term) Represents the cumulative historical deviation, used to eliminate steady-state error, so that the angle deviation after long-term operation approaches zero; differential term It represents the changing trend of the sensing angle deviation, provides advanced adjustment, and suppresses oscillations that may be caused by rapid fluctuations in the plasma state.

[0169] Finally, the bias correction amount output by the PID calculation is... Superimposed on the target bias To obtain the total bias voltage It is applied to the top of the cage or the corresponding insulating isolation part.

[0170] Figure 16 A flowchart illustrating a plasma etching angle control method provided in another embodiment of this application. Figure 16 As shown, in some embodiments, after determining the potential difference based on a preset reference and the sheath potential at each monitoring location in step S603, and before generating the bias correction amount, the following steps are further included:

[0171] Step S701: When the potential difference exceeds the preset threshold, adjust the angle between the plane at the top of the cage and the bearing surface to reduce the potential difference.

[0172] The preset threshold is a potential difference threshold set according to the allowable angle deviation range of the process. When the potential difference exceeds this threshold, it indicates that the current asymmetric state of the sheath electric field has significantly deviated from the target state. Considering that relying solely on the electrical bias correction in step S604 may not be sufficient to adjust the angle deviation to an acceptable range, or the required bias correction amount may be too large, exceeding the reasonable output range of the adjustable bias power supply.

[0173] Therefore, the control unit does not directly calculate the bias correction amount, but first performs a mechanical coarse adjustment: the tilt angle adjustment frame adjusts the angle between the plane where the top of the cage is located and the bearing surface. The direction and magnitude of the adjustment are determined according to the sign and magnitude of the potential difference. By changing the tilt angle of the top of the cage, the geometric relationship between the top of the cage and the bearing surface is directly changed, correcting the asymmetric shape of the sheath electric field from the source, making the potential at each monitoring position along the tilt direction more consistent. Since the mechanical adjustment directly changes the geometric basis for generating the asymmetric electric field, the correction effect for large deviations is significant and the electrical system does not need to operate under extreme bias conditions.

[0174] Step S702: After the included angle is adjusted, the target bias is re-determined based on the adjusted included angle, and then a bias correction amount is generated based on the potential difference. The re-determined target bias and the bias correction amount are superimposed and applied to the top of the cage.

[0175] After the angle adjustment is completed, the geometric relationship between the top of the cage and the bearing surface has changed, and the original target bias is no longer applicable to the new angle. Therefore, the control unit redetermines the target bias based on the adjusted new angle. The correspondence between the target bias and the angle is obtained through a pre-calibrated data table or function relationship, and the corresponding target bias value is queried or calculated based on the current angle.

[0176] After the target bias is redefined, the control unit obtains the potential difference detected by the current sheath potential monitoring unit (which has been significantly reduced after mechanical coarse adjustment), and enters step S604. Based on the potential difference, a bias correction amount is generated and superimposed on the redefined target bias to form a total bias applied to the top of the cage, thus completing the electrical fine adjustment.

[0177] In summary, the plasma etching angle control method provided in each embodiment determines the basic target bias by obtaining the target incident angle, detects the sheath potential at multiple positions in the tilt direction in real time and calculates the potential difference based on a preset benchmark, and then generates a bias correction amount and dynamically superimposes it onto the target bias, forming a closed-loop feedback control of the sheath electric field, so that the ion incident angle remains stable at the target value under interference factors such as plasma state fluctuations and cage thermal deformation.

[0178] In the bias correction generation stage, either the potential difference can be directly calculated using PID, or the potential difference can be converted into an angle deviation before PID calculation. The former is simple and efficient, while the latter has a clear physical meaning and intuitive parameter tuning.

[0179] Furthermore, a two-stage control strategy combining mechanical coarse adjustment and electrical fine adjustment is introduced. When the potential difference is too large, a large-scale correction is first made by adjusting the tilt angle of the cage, and then the residual deviation is finely compensated by dynamic bias voltage. This not only broadens the angle adjustment range, but also avoids the electrical system from working in extreme conditions for a long time.

[0180] Overall, this method constructs a multi-level, fully closed-loop angle control system, encompassing everything from geometric foundation settings to dynamic electric field compensation, from fine electrical adjustment to large-scale mechanical correction, and from real-time closed-loop control to abnormal safety protection. This significantly improves the accuracy, anti-interference capability, process repeatability, and operational reliability of tilt etching, providing a reliable control method for the fabrication of advanced micro-nano devices such as high aspect ratio structures, diffraction grating molds, and photonic crystals.

[0181] In the above embodiments, implementation can be achieved, in whole or in part, by software, hardware, firmware, or any combination thereof. Furthermore, as those skilled in the art will understand, the principles herein can be reflected in a computer program product on a computer-readable storage medium pre-loaded with computer-readable program code. Any tangible, non-transitory computer-readable storage medium may be used, including magnetic storage devices (hard disks, floppy disks, etc.), optical storage devices (CDs, DVDs, Blu-ray discs, etc.), flash memory, and / or the like. These computer program instructions can be loaded onto a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to form a machine, such that instructions executing on the computer or other programmable data processing apparatus can generate means for performing a specified function. These computer program instructions can also be stored in a computer-readable storage medium that can instruct the computer or other programmable data processing apparatus to operate in a particular manner, such that instructions stored in the computer-readable storage medium can form an article of manufacture, including means for implementing the specified function. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to perform a series of operational steps on the computer or other programmable apparatus to produce a computer-implemented process, such that instructions executing on the computer or other programmable apparatus can provide steps for implementing the specified function.

[0182] This document describes various exemplary embodiments with reference to them. However, those skilled in the art will recognize that changes and modifications can be made to the exemplary embodiments without departing from the scope of this document. For example, various operational steps and components for performing operational steps can be implemented in different ways depending on the specific application or considering any number of cost functions associated with the operation of the system (e.g., one or more steps can be deleted, modified, or combined with other steps).

[0183] While the principles herein have been illustrated in various embodiments, numerous modifications to the structures, arrangements, proportions, elements, materials, and components, particularly suited to specific environments and operational requirements, may be used without departing from the principles and scope of this disclosure. These modifications and other alterations or alterations will be included within the scope of this document. Those skilled in the art will recognize that many changes can be made to the details of the above embodiments without departing from the fundamental principles of the invention.

Claims

1. A plasma etching apparatus, characterized in that, include: Etching cavity; A plasma generating assembly for generating plasma within the etching cavity; A carrier is disposed within the etching cavity, the carrier having a bearing surface for bearing the material to be etched; A Faraday cage, the Faraday cage including a conductive cage top, the cage top being disposed within the etching cavity, and the cage top being spaced apart from the bearing surface; The cage includes a tilt angle adjustment frame, wherein the plane containing the top of the cage has an angle with the bearing surface, the top of the cage is mounted above the bearing body via the tilt angle adjustment frame, and the tilt angle adjustment frame is used to adjust the tilt angle of the plane containing the top of the cage relative to the bearing surface; the tilt angle adjustment frame includes a first drive assembly and at least two first pillars; each first pillar supports the top of the cage, and the first drive assembly is used to drive at least one first pillar to move to adjust the height of at least one first pillar to adjust the tilt angle of the top of the cage; Alternatively, the bearing surface has an angle with the bottom wall of the etching cavity, and the bearing is installed in the etching cavity by the tilt angle adjustment frame. The tilt angle adjustment frame is used to adjust the tilt angle of the bearing surface relative to the bottom wall of the etching cavity. The tilt angle adjustment frame includes a second drive assembly and at least two second pillars, each of the second pillars supporting the bearing. The second drive assembly is used to drive at least one second pillar to move to adjust the height of at least one second pillar to adjust the tilt angle of the bearing surface.

2. The plasma etching apparatus according to claim 1, characterized in that, When the top of the cage is mounted above the carrier via the tilt angle adjustment frame, the first drive assembly is located outside the etching cavity, one end of the first pillar is located outside the etching cavity and connected to the first drive assembly, and the other end of the first pillar is located inside the etching cavity and connected to the top of the cage. The plasma etching apparatus further includes a magnetohydrodynamic sealing assembly, which is installed on the etching cavity and is used to dynamically vacuum seal the etching cavity with the first support column.

3. The plasma etching apparatus according to claim 1 or 2, characterized in that, The top of the cage includes an edge support, a support frame, and multiple openings. The support frame is a dense structure made of conductive material. The support frame extends within the annular structure enclosed by the edge support and connects to the edge support. The support frame includes multiple support rods, which interlock to separate the multiple openings. The openings have multiple through holes penetrating the outer side and the inner side of the top of the cage, allowing plasma to enter the Faraday cage through the through holes in a direction perpendicular to the top of the cage.

4. The plasma etching apparatus according to claim 3, characterized in that, At least a portion of the supporting frame and / or at least a portion of the edge support portion forms a hollow structure inside, the hollow structure including an inlet and an outlet, the hollow structure being used to introduce non-conductive coolant.

5. The plasma etching apparatus according to claim 3, characterized in that, The top of the cage is made of high-purity aluminum with a purity of not less than 99.999%, and the surface of the high-purity aluminum is formed into an anodized aluminum ceramic layer through an anodizing process.

6. The plasma etching apparatus according to claim 1 or 2, characterized in that, The top of the cage includes a mesh-shaped first cage and a mesh-shaped second cage. The first cage has multiple first through holes penetrating the outer side and the inner side of the first cage. The second cage has multiple second through holes penetrating the outer side and the inner side of the second cage. The first cage and the second cage are arranged opposite to each other and have a gap between them. The gap communicates with the interior of the etching cavity so that the process gas in the etching cavity can enter the gap. The first through holes are used to allow plasma to enter the gap in a direction perpendicular to the first cage, and the second through holes are used to allow particles in the gap to pass through.

7. The plasma etching apparatus according to claim 6, characterized in that, The second cage is positioned closer to the carrier than the first cage; the opening ratio of the first cage is less than or equal to the opening ratio of the second cage.

8. The plasma etching apparatus according to claim 7, characterized in that, The diameter of the first through hole is larger than the diameter of the second through hole, and the density of the first through hole is smaller than the density of the second through hole; Alternatively, the diameter of the first through hole is equal to the diameter of the second through hole, and the density of the first through hole is less than or equal to the density of the second through hole.

9. The plasma etching apparatus according to claim 1 or 2, characterized in that, When the top of the cage is mounted above the carrier via the tilt angle adjustment frame, the plasma etching apparatus further includes: An adjustable bias power supply is used to provide a bias voltage to the top of the cage to form an asymmetric electric field for deflecting incident ions in the sheath layer below the top of the cage. A sheath potential monitoring unit is used to detect the sheath potential at at least two monitoring positions in the area between the top of the cage and the bearing surface. Each monitoring position is distributed along the direction in which the top of the cage is inclined relative to the bearing surface, and has a different height relative to the bearing surface. The control unit, connected to the sheath potential monitoring unit and the adjustable bias power supply, is used to determine the target bias voltage according to the target incident angle and control the adjustable bias power supply to provide the target bias voltage to the top of the cage; receive the sheath potential at at least two monitoring positions output by the sheath potential monitoring unit, determine the potential difference based on a preset reference and the sheath potential at each monitoring position, generate a bias correction amount according to the potential difference, and control the adjustable bias power supply to superimpose the bias correction amount onto the target bias voltage so that ions in the plasma are incident at the target incident angle.

10. The plasma etching apparatus according to claim 9, characterized in that, The sheath potential monitoring unit includes at least two Langmuir probes arranged along the direction of inclination relative to the bearing surface at the top of the cage, with each Langmuir probe corresponding to one of the monitoring positions.

Images