Plasma etching apparatus and method of operation thereof

Abstract

This invention provides a plasma etching apparatus, comprising: a reaction chamber with a base inside; a confinement ring surrounding the periphery of the base, the confinement ring having multiple gas channels; a middle grounding ring and a lower grounding ring disposed around the periphery of the base, extending radially and axially along the base, respectively; the middle grounding ring connecting the lower grounding ring and the sidewall of the reaction chamber, the bottom of the lower grounding ring connecting to the bottom wall of the reaction chamber; a radio frequency shielding area within the reaction chamber formed by the outer side of the lower grounding ring, the lower side of the middle grounding ring, and the reaction chamber; at least one coil disposed around the lower grounding ring within the radio frequency shielding area; a horizontal magnetic field component generated by the coil at the location of the confinement ring is used to restrict charged particles discharged from the plasma reaction region from flowing into the exhaust region through the gas channels. This invention also provides a method for operating the plasma etching apparatus. This invention can improve pumping efficiency, ensure sufficient electron-ion collision rate, and reduce the risk of plasma leakage.

Description

Technical Field

[0001] This invention relates to the field of semiconductor equipment, and in particular to a plasma etching apparatus and its operating method. Background Technology

[0002] During plasma etching, various process gases are injected into the reaction chamber of the plasma etching apparatus. Under the influence of the radio frequency electric field within the reaction chamber, they are excited into plasma (containing electrons, ions, and reactive free radicals). The reaction between the plasma and the wafer produces by-products, which need to be removed promptly to ensure the smooth progress of the etching reaction. Therefore, currently used plasma etching apparatuses employ a flowing gas reaction chamber, where reactive gases are continuously injected from one end of the chamber, while by-products and other unreacted substances are continuously removed from the other end using a vacuum pump.

[0003] During evacuation, plasma quenching is necessary to prevent plasma from corroding the vacuum pump and evacuation pipes, and to avoid potential radio frequency leakage due to plasma conductivity. Currently, a commonly used quenching device is a multi-layered, nested annular plasma confinement ring (FEIS ring) surrounding the lower electrode. This design allows for both unrestricted plasma reaction space and unobstructed transfer port. This confinement ring increases the probability of electron and ion collisions due to its narrow ring spacing (typically 1.5 mm) and relatively large ring plate height (17.4 mm), resulting in the majority of electrons and ions being lost through collisions on the ring plates, thus quenching the plasma. However, this design comes at the cost of dividing the evacuation path into numerous narrow gaps by a dozen to several dozen ring plates, significantly restricting the flow conduction of the evacuation path and preventing the achievement of atmospheric flow and low-pressure operating environments.

[0004] In plasma etching with a critical dimension (CD) of less than 10 nm, such as in the etching of small holes (BARC, bottom anti-reflective coatings), BARC residue can easily remain at the bottom of the hole, affecting subsequent processes. This residue is due to the extremely small feature size, which makes the entry of process gases and the removal of byproducts more difficult. To improve process gas entry and byproduct removal, a process regime that allows for lower pressure and higher gas flow rates within the reaction chamber is preferred, thus requiring improved gas conductance during extraction.

[0005] Based on current technology, there are only two ways to improve plasma conductivity: reducing the ring plate height (the distance between the upper and lower surfaces of the ring plate) or increasing the ring plate spacing. Both methods reduce the electron and ion collision rate, increasing the risk of plasma leakage. How to improve the pumping conductivity while ensuring a sufficient electron and ion collision rate and reducing the risk of plasma leakage is a pressing problem that needs to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a plasma etching apparatus and operating method. By using a coil positioned within a radio frequency (RF) shielding zone to generate a horizontal magnetic field component within a confinement ring, the collision rate between charged particles and the sidewalls of the gas channel is increased, reducing the risk of plasma leakage. Since the coil is positioned in a non-RF environment, its performance and lifespan are guaranteed, and there is no concern about RF energy leaking to the outside of the reaction chamber through the coil's power lines. Furthermore, the confinement ring can have a larger plate spacing, significantly improving the gas flow conduction and meeting the requirements of high-flow-rate, low-pressure processes.

[0007] To achieve the above objectives, the present invention provides a plasma etching apparatus, comprising:

[0008] The reaction chamber contains a base.

[0009] A confinement ring is arranged around the periphery of the base, and the confinement ring has multiple gas channels;

[0010] A middle grounding ring and a lower grounding ring are both disposed around the base. The middle grounding ring is arranged radially along the base, and its two ends are respectively connected to the lower grounding ring and the side wall of the reaction chamber. The lower grounding ring is arranged axially along the base, with its top connected to the middle grounding ring and its bottom connected to the bottom wall of the reaction chamber. The reaction chamber has a radio frequency shielding area, which is formed by the outside of the lower grounding ring, the bottom of the middle grounding ring, and the side wall of the reaction chamber.

[0011] At least one coil is disposed around the lower grounding ring and located within the radio frequency shielding area; the coil generates a horizontal magnetic field component in the confinement ring to increase the collision of charged particles with the sidewalls of the gas channel.

[0012] Optionally, the limiting ring includes a plurality of concentrically arranged ring plates, which are radially arranged along the base, and the gap between two adjacent ring plates forms the gas passage.

[0013] Optionally, the width of the gas passage decreases from the inside to the outside along the radial direction of the restricting ring.

[0014] Optionally, the coil is a single-turn coil, and the single-turn coil is coaxial with the base.

[0015] Optionally, the number of single-turn coils may be multiple, with at least two single-turn coils arranged radially along the base.

[0016] Optionally, the number of the single-turn coils is multiple, with at least two of the single-turn coils arranged along the axial direction of the base.

[0017] Optionally, the coil is a multi-turn coil, which is wound around the central axis of the base along the axial or radial direction of the base.

[0018] Optionally, the number of multi-turn coils may be multiple, with at least two of the multi-turn coils located at different heights.

[0019] Optionally, the number of multi-turn coils is multiple, with at least two of the multi-turn coils wound along the axial direction of the base arranged radially along the base.

[0020] Optionally, the plasma etching apparatus may further include multiple power sources, each for supplying power to one of the coils.

[0021] Optionally, at least two of the coils may have different current magnitudes.

[0022] Optionally, the surface of the coil has an insulating coating, which is at least one of polyimide and polytetrafluoroethylene.

[0023] Optionally, the coil is housed within a protective tube coaxial with it; the protective tube is made of a non-magnetic material resistant to plasma corrosion.

[0024] Optionally, the protective tube is made of aluminum alloy, and the surface of the protective tube has an aluminum oxide film obtained by anodizing.

[0025] The present invention also provides a method for operating a plasma etching apparatus, comprising:

[0026] Provide a plasma etching apparatus as described in this invention;

[0027] The wafer is placed on a substrate and subjected to plasma etching.

[0028] Power is supplied to the coil to generate a magnetic field. The horizontal magnetic field component generated by the magnetic field at the location of the confinement ring restricts the flow of charged particles discharged from the plasma reaction region into the exhaust region through the gas channel of the confinement ring.

[0029] Optionally, the method of operating the plasma device further includes:

[0030] Adjust the current of the corresponding coil based on its position.

[0031] Compared with the prior art, the plasma etching apparatus of the present invention has at least the following advantages:

[0032] 1) In the plasma etching apparatus of the present invention, the outer part of the lower grounding ring, the lower part of the middle grounding ring, and the reaction chamber form a radio frequency shielding area. A coil is arranged in this radio frequency shielding area, and a horizontal magnetic field component (hereinafter referred to as the horizontal magnetic field component) is generated in the confinement ring by the coil. This ensures that the charged particles discharged from the plasma reaction region have a sufficient collision rate with the sidewalls of the gas channel, reducing the risk of plasma leakage. Furthermore, the ring plates of the confinement ring can have a larger plate spacing, which greatly improves the gas flow conduction and can meet the process requirements of high flow rate and low gas pressure.

[0033] 2) By adjusting the number of turns, height, and quantity of coils used, a sufficiently strong horizontal magnetic field component can be achieved between any two adjacent ring plates. This allows for a larger gap between adjacent ring plates, significantly improving pumping efficiency. Furthermore, this invention can dynamically adjust the horizontal magnetic field component of the limiting ring by adjusting the coil current in real time. Only a small current is needed to ensure a high collision rate between charged particles and the sidewalls of the gas channel, preventing overheating and potential safety hazards caused by excessive current, thus further ensuring the safety of wafer processing.

[0034] 3) Even when operating in the high-temperature environment of the reaction chamber for extended periods, the coil can continuously and stably generate the required magnetic field, without concern about the confinement ring losing its ability to restrain the plasma. Since the coil is located in a non-RF environment, there is no need to worry about RF energy leaking outside the reaction chamber through the coil's power lines without the use of filtering equipment, improving wafer processing safety while reducing economic costs. The gas in the RF shielding area contains only electrically neutral free radicals and reaction byproducts; therefore, the coil is not corroded by the plasma, resulting in good performance and a long service life.

[0035] 4) The vertical magnetic field generated by the coil in the reaction chamber can further increase the residence time and density of the plasma in the reaction chamber, and improve the uniformity of the plasma distribution in the reaction chamber.

[0036] 5) This invention does not require changing the layout of existing components in the reaction chamber, and the installation and adjustment of the coil are quick and convenient, making it highly practical. Attached Figure Description

[0037] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the drawings in the following description are one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0038] Figure 1 This is a schematic diagram of a plasma etching apparatus;

[0039] Figure 2 This is a schematic diagram of the plasma etching apparatus in Embodiment 1 of the present invention;

[0040] Figure 3 This is a schematic diagram illustrating the deflection of charged particles under the influence of the Lorentz force in Embodiment 1 of the present invention.

[0041] Figure 5 This is a schematic diagram of two single-turn coils arranged radially along the base inside the reaction chamber in Embodiment 2 of the present invention;

[0042] Figure 6 In another embodiment of the present invention, at least two single-turn coils are located at different heights among a plurality of single-turn coils arranged radially along the base;

[0043] Figure 7 , Figure 8 These are schematic diagrams of a multi-turn coil wound around the central axis of a base in the circumferential and radial directions, respectively, in Embodiment 3 of the present invention.

[0044] Figure 9 This is a schematic diagram showing two multi-turn coils located at different heights in another embodiment of the present invention;

[0045] Figure 10 This is a schematic diagram of two multi-turn coils wound along the axial direction of the base and arranged radially along the base, as shown in another embodiment of the present invention.

[0046] Figure 11 This is a flowchart illustrating the operation method of the plasma etching apparatus in this invention. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0049] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0050] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0051] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrases "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0052] Furthermore, in the description of this application, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0053] Figure 1 A plasma etching apparatus 1 is shown, comprising a reaction chamber 10, which is substantially cylindrical and has substantially vertical sidewalls. Within the reaction chamber 10 are a gas spray head 110 and a base 120 disposed opposite to each other. The spray head 110 serves as the upper electrode of the plasma etching apparatus 1, and the base 120 serves as the lower electrode. Typically, the region between the upper and lower electrodes is a plasma reaction region A, which generates high-frequency energy to ignite and sustain the plasma.

[0054] The base 131 is used to place the wafer to be processed. Reactive gas is introduced into the reaction chamber 10 from the gas spray head 110. One or more radio frequency (RF) power supplies can be applied individually to the lower electrode or simultaneously to both the upper and lower electrodes to deliver RF power to the lower electrode or both electrodes, thereby generating a large electric field within the reaction chamber 10. Most of the electric field is contained within the plasma reaction region A between the upper and lower electrodes. This electric field accelerates a small number of electrons present within the reaction chamber 11, causing them to collide with gas molecules of the introduced reactive gas. These collisions lead to ionization of the reactive gas and excitation of the plasma, thereby generating plasma within the reaction chamber 10. The plasma contains a large number of active particles such as electrons, ions, excited-state atoms, molecules, and free radicals. These active particles can undergo various physical and chemical reactions with the surface of the wafer to be processed, altering the morphology of the wafer surface, thus completing the etching process.

[0055] A confinement ring 130 is disposed around the base 120 between the plasma reaction region A and the exhaust region C. During the etching process, the reactant gases and byproduct gases used enter the exhaust region C through the gaps between the ring plates 131 of the confinement ring 130, and are extracted to the outside of the reaction chamber 10 by an exhaust device (e.g., a vacuum pump, not shown) connected to the exhaust region C. After the plasma in the gas enters the confinement ring 130, the charged particles collide with the sidewalls of the ring plates 131 and are quenched, thereby preventing the plasma from entering the exhaust region C and avoiding contamination of the inner wall of the reaction chamber and the exhaust pipe below the confinement ring.

[0056] In plasma etching processes with feature sizes smaller than 10 nm, we need to improve the gas conduction of the extraction flow to establish a lower gas pressure within the reaction chamber 10. This facilitates the extraction of reaction byproducts and reduces their deposition on the wafer. Based on current processes, there are only two ways to improve the conduction: reducing the ring height or increasing the ring spacing. Both methods reduce the electron and ion collision rate, increasing the risk of plasma leakage.

[0057] This invention provides a plasma etching apparatus and method that can improve the airflow conduction of the pump while ensuring a sufficient electron and ion collision rate and reducing the risk of plasma leakage.

[0058] Example 1

[0059] Figure 2 The plasma etching apparatus 2 of this embodiment is shown, which includes a reaction chamber 20, and a wafer transfer port (not shown) is provided on the side wall of the reaction chamber. The reaction chamber 20 is provided with: a gas spray head 210, a base 220, a confinement ring 230, a middle grounding ring 240 and a lower grounding ring 250, at least one coil 260 and at least one power supply (not shown).

[0060] like Figure 2 As shown, the confinement ring 230 is arranged around the periphery of the base 220 and avoids the wafer transfer port on the side wall of the reaction chamber, so as not to affect the wafer transfer. The confinement ring 230 includes a plurality of concentric ring plates 231, which are arranged radially along the base 220. The gap between two adjacent ring plates 231 forms a gas channel, through which the reaction byproducts in the plasma reaction region A flow into the exhaust region C.

[0061] like Figure 2 As shown, the intermediate grounding ring 240 and the lower grounding ring 250 are both disposed around the base 220, with the intermediate grounding ring 240 arranged radially along the base 220. The two ends of the intermediate grounding ring 240 are connected to the lower grounding ring 250 and the sidewall of the reaction chamber, respectively. The lower grounding ring 250 is arranged axially along the base 220, with its top connected to the intermediate grounding ring 240 and its bottom connected to the bottom wall of the reaction chamber. The intermediate grounding ring 240 and the lower grounding ring 250 are made of conductors and are electrically connected to form a radio frequency grounding loop within the reaction chamber. The limiting ring 230 is at a floating potential, and the intermediate grounding ring 240 is at zero potential. Radio frequency power is transmitted between the intermediate grounding ring 240 and the limiting ring 230 through capacitive coupling (no DC conduction). This shields the radio frequency energy above the middle grounding ring 240, preventing the generation of secondary plasma and dissipating the accumulated charge on the confinement ring 230. It is easy to understand that a radio frequency shielding area is formed by the outside of the lower grounding ring 250, the bottom of the middle grounding ring 240, and the reaction chamber 20.

[0062] Coil 260 surrounds the lower grounding ring 250 and is disposed within the radio frequency shielding area. Coil 260 and base 220 are coaxial. The coil 260 generates a horizontal magnetic field component (referred to as the horizontal magnetic field component) in the confinement ring. The horizontal magnetic field component can increase the collision between charged particles and the sidewall of the gas channel, thereby ensuring plasma confinement efficiency while increasing the gap width.

[0063] Even when operating in the high-temperature environment within the reaction chamber for extended periods, coil 260 can continuously and stably generate the required magnetic field, without concern that the confinement ring 230 will lose its ability to confine the plasma. This invention requires no alteration to the existing component layout within the reaction chamber 20, and the installation and adjustment of coil 260 are quick and convenient, demonstrating excellent practicality.

[0064] Since the reaction chamber 20 of the plasma etching apparatus 2 uses radio frequency (RF) as the power source for the plasma, an RF electric field is distributed throughout most of the space within the reaction chamber 20, and the RF current also propagates along the metal surface of the inner wall of the reaction chamber. In this invention, the coil 260 is placed in the RF shielding area. The gas in the RF shielding area contains only electrically neutral free radicals and reaction byproducts, so the coil 260 is not affected by the plasma and the RF electric field, resulting in better performance and a longer service life. Even without configuring a filter device for the coil 260 (which is usually bulky and cumbersome to use), there is no need to worry about RF energy leaking to the outside of the reaction chamber 20 through the power line of the coil 260, improving wafer processing safety while significantly reducing economic costs.

[0065] In one embodiment, the coil 260 is disposed within a protective tube coaxial with it. The protective tube is made of a non-magnetic material resistant to plasma corrosion (e.g., aluminum alloy), and its surface has an aluminum oxide film obtained through anodizing. Meanwhile, the surface of the coil 260 has an insulating coating (e.g., at least one of polyimide and polytetrafluoroethylene). The protective tube and insulating coating further protect the coil 260 from the adverse effects of plasma and radio frequency electric fields.

[0066] In this embodiment, there is one coil 260. The number of coils 260 can be set according to actual needs. A single-turn coil is used in this embodiment, but multi-turn coils can also be used in other embodiments. In this invention, there are no restrictions on the number, number of turns, height, diameter, or current of the coils 260, as long as the conductivity and plasma confinement efficiency of the confinement ring 230 can be improved.

[0067] like Figure 3 As shown in the figure This represents the horizontal magnetic field component at the location of the confinement ring. This represents the velocity of the charged particles entering the gas channel. The charged particles are deflected by the Lorentz force F in this horizontal magnetic field component (their velocity changes). The charged particles in the plasma move along a spiral trajectory and eventually collide with the sidewall of the ring plate 231. Therefore, charged particles in the plasma are more likely to move towards the sidewall of the ring plate than to pass directly through the confinement ring 230. This horizontal magnetic field component improves the confinement of the plasma at each gap, thus allowing for an appropriate increase in the width of each gap and effectively improving the pumping efficiency of the confinement ring 230.

[0068] Due to the airflow within confinement ring 230, the flow direction of electrons and ions in the gas channel is primarily from top to bottom, and they are not affected by vertical magnetic field lines. Therefore, the vertical magnetic field component at the location of the confinement ring (referred to as the vertical magnetic field component) does not significantly improve the collision rate of charged particles. We aim to increase the horizontal magnetic field component at the location of the confinement ring in coil 260 to increase the plasma collision rate.

[0069] The horizontal magnetic field component is affected by two factors: magnetic field strength and magnetic field direction. The greater the magnetic field strength, the larger the horizontal magnetic field component. The closer the magnetic field direction is to horizontal, the larger the horizontal magnetic field component. By increasing the vertical distance between coil 260 and the limiting ring 230, the magnetic field direction at the location of the limiting ring can be made approximately horizontal. However, the greater the vertical distance between coil 260 and the limiting ring 230, the smaller the magnetic field strength generated by coil 260 at the location of the limiting ring. By adjusting the height of coil 260, a balance can be achieved between magnetic field strength and magnetic field direction, resulting in a larger horizontal magnetic field component at the location of the limiting ring. It is important to emphasize that even after coil 260 is installed and fixed, this invention can still dynamically adjust the horizontal magnetic field component at the location of the limiting ring by adjusting the current of coil 260 in real time, effectively ensuring the collision rate of charged particles.

[0070] like Figure 2 As shown, in this embodiment, the confinement ring 230 is divided into an inner region 230a and an outer region 230b along the radial direction. Although the inner region 230a, which is closer to the base 220, has a larger vertical magnetic field component according to the curvature distribution of the magnetic induction lines, the total magnetic field strength of the inner region 230a is relatively large. Therefore, compared with the outer region 230b, the inner region 230a still has a stronger horizontal magnetic field component. Figure 2 It can also be seen that the magnetic field lines in the outer region 230b are approximately horizontal, and the magnetic field strength in the outer region 230b gradually decreases from the inside to the outside (the distribution of magnetic field lines gradually becomes sparser). Therefore, the strength of the horizontal magnetic field component in the outer region 230b also gradually decreases from the inside to the outside. In summary, the overall strength of the horizontal magnetic field component at the location of the limiting ring gradually decreases from the inside to the outside. It is easy to understand that along the radial direction away from the base 220, the width of the gas channel also gradually decreases (the width of the outermost gas channel is still greater than the width of the gas channel in the prior art).

[0071] This invention requires only a small current to generate a sufficiently strong horizontal magnetic field component at the location of the confinement ring, ensuring plasma confinement efficiency, reducing the ring height, and improving the pumping conduction of the confinement ring 230. While saving energy, it also prevents the coil 260 from overheating due to excessive current, thus effectively ensuring the safety of wafer processing.

[0072] On the other hand, such as Figure 2 As shown, within a radial distance of less than r (where r is the radius of coil 260) from the central axis of base 220, coil 260 primarily generates a vertical magnetic field. The magnetic field The Lorentz force is generated on electrons in the plasma (which can be used for ionization collisions). The trajectory of the electrons is deflected by the Lorentz force, and the linear motion of the electrons becomes orbital motion around the magnetic field. The spiral motion of the magnetic induction lines is equivalent to increasing the movement path of electrons and increasing the probability of collisions between electrons and gas molecules. Therefore, it can further increase the residence time and density of plasma in the reaction chamber, and improve the uniformity of plasma distribution and etching efficiency in the reaction chamber.

[0073] Example 2

[0074] like Figure 4 As shown, in this embodiment, two single-turn coils 360a and 360b are arranged radially along the base 320 within the radio frequency shielding area. Coils 360a and 360b are coaxial with the base 320, and the diameter of coil 360b is larger than that of coil 360a. As explained in the previous embodiment, under the sole action of coil 360a, the horizontal magnetic field component of the outer region 330b is stronger than that of the inner region 330a. In this embodiment, the radius R of coil 360b is approximately the same as the outer diameter of the inner region 330a. Figure 4 Only the magnetic field lines of coil 360b are shown. Within a radial distance of less than R from the central axis of the base, coil 360b primarily generates a vertical magnetic field, having almost no effect on the horizontal magnetic field component of the inner region 330a. The magnetic field strength of coil 360b in the outer region 330b is greater, generating a stronger horizontal magnetic field component to compensate for the insufficient horizontal magnetic field component generated by coil 360a in the outer region 330b. Compared to Embodiment 1, the gap width in the outer region 330b can be further appropriately increased, further improving the conductivity of the confinement ring 330.

[0075] In another embodiment, at least three coils 360 are arranged radially along the base 320 within the radio frequency shielding area. It is important to emphasize that each coil 360 is connected to an independent power supply, and the current of each coil 360 can be adjusted independently. By adjusting the diameter and / or current of each coil 360, a horizontal magnetic field component of approximately the same intensity can be achieved in each slot 360, and the width of each slot can be approximately the same. Since each slot has a large conductance, the pumping efficiency of the confinement ring 330 is further improved.

[0076] like Figure 5 As shown, in another embodiment, single-turn coils 360a and 360b are arranged along the axial direction of the base 320 to enhance the horizontal magnetic field component at the location of the limiting ring. The intensity gradient of the horizontal magnetic field component is larger in the radial direction of the limiting ring 330. Compared to Embodiment 1, the width of each gap can be further appropriately increased, and the gaps closer to the base 320 are increased in width more than those farther from the base 320.

[0077] like Figure 6 As shown, in another embodiment, multiple single-turn coils 360 ( Figure 6 The diagram shows three coils arranged radially along the base 320, with at least two single-turn coils 360 having different heights. This not only enhances the horizontal magnetic field component at the location of the limiting ring as a whole, but also reduces the intensity gradient of the horizontal magnetic field component in the radial direction of the limiting ring 330, minimizes the difference in width between different gaps, and ensures that each gap has a large conductivity.

[0078] Example 3

[0079] To further increase the horizontal magnetic field component at the location of the limiting ring, a multi-turn coil 460 is used in this embodiment.

[0080] Figure 7 , Figure 8 The multi-turn coil 460 is wound around the central axis of the base 420 along the axial and radial directions, respectively. Along the radial direction of the limiting ring 430, from the inside out... Figure 7 , Figure 8 The intensity of the horizontal magnetic field components in the gaps all decreases, as do the widths of the gaps. Figure 7 , Figure 8 In this case, the width of each gap can be appropriately increased. (And) Figure 7 compared to, Figure 8 The intensity gradient of the horizontal magnetic field component is relatively small.

[0081] In another embodiment, such as Figure 9 As shown, the two multi-turn coils 460 (the number of coils is only an example and not a limitation of the invention) are located at different heights. The purpose of this embodiment is... Figure 5 Both aim to enhance the horizontal magnetic field component at the location of the limiting ring. Since the multi-turn coil 460 can generate a larger magnetic field, this embodiment is clearly superior to... Figure 5 The effect is better.

[0082] In another embodiment, at least two multi-turn coils 460 wound axially along the base 420 are arranged radially along the base 420. The purpose of this embodiment is... Figure 4 Both aim to enhance the horizontal magnetic field component at the location of the overall confinement ring 430, while also minimizing the intensity gradient of the horizontal magnetic field component in the radial direction of the confinement ring 430, thus ensuring greater conductivity in each gap of the confinement ring 430. Since the multi-turn coil 460 can generate a larger magnetic field, this embodiment is clearly superior to... Figure 4 The effect is better.

[0083] In some embodiments, single-turn coils and multi-turn coils can be used simultaneously in the reaction chamber, as long as the plasma confinement efficiency and flow conductance of the confinement ring can be improved. This invention does not impose any limitations.

[0084] The present invention also provides a method for operating a plasma etching apparatus, such as... Figure 11 As shown, it includes:

[0085] Step S1: Provide a plasma etching apparatus as described in this invention;

[0086] Step S2: Place the wafer on the substrate and perform plasma etching.

[0087] Step S3: Power is supplied to the coil to generate a magnetic field. The magnetic field generates a horizontal magnetic field component in the limiting ring, which increases the collision between charged particles and the sidewall of the gas channel.

[0088] In one embodiment, the operation method of the plasma etching apparatus further includes:

[0089] Adjust the current of the corresponding coil based on its position.

[0090] For example, when the vertical distance between the coil and the limiting ring is small, the vertical magnetic field component at the location of the limiting ring is larger than the horizontal magnetic field component, so the current in the coil can be appropriately increased. Alternatively, for multiple coils arranged radially along the base, the current in these coils can be gradually reduced from the inside out, so that the gaps in the limiting ring have approximately the same horizontal magnetic field component, the width of each gap is approximately the same, and the limiting ring has uniform conductivity.

[0091] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0092] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A plasma etching apparatus, characterized in that, include: The reaction chamber contains a base. A confinement ring is arranged around the periphery of the base, and the confinement ring has multiple gas channels; A middle grounding ring and a lower grounding ring are both disposed around the base. The middle grounding ring is arranged radially along the base, and its two ends are respectively connected to the lower grounding ring and the side wall of the reaction chamber. The lower grounding ring is arranged axially along the base, with its top connected to the middle grounding ring and its bottom connected to the bottom wall of the reaction chamber. The reaction chamber has a radio frequency shielding area, which is formed by the outside of the lower grounding ring, the bottom of the middle grounding ring, and the side wall of the reaction chamber. At least one coil is disposed around the lower grounding ring and located within the radio frequency shielding area; The coil generates a horizontal magnetic field component in the limiting ring, which increases the collision between charged particles and the sidewalls of the gas channel.

2. The plasma etching apparatus as described in claim 1, characterized in that, The limiting ring includes multiple concentric ring plates arranged radially along the base, with the gap between two adjacent ring plates forming the gas channel.

3. The plasma etching apparatus as described in claim 1, characterized in that, Along the radial direction of the limiting ring, the width of the gas passage decreases from the inside to the outside.

4. The plasma etching apparatus as described in claim 1, characterized in that, The coil is a single-turn coil, and the single-turn coil is coaxial with the base.

5. The plasma etching apparatus as described in claim 4, characterized in that, The number of the single-turn coils is multiple, and at least two of the single-turn coils are arranged radially along the base.

6. The plasma etching apparatus as described in claim 4, characterized in that, The number of single-turn coils is multiple, and at least two of the single-turn coils are arranged along the axial direction of the base.

7. The plasma etching apparatus as claimed in claim 1, characterized in that, The coil is a multi-turn coil, which is coiled around the central axis of the base along the axial or radial direction of the base.

8. The plasma etching apparatus as described in claim 7, characterized in that, The number of multi-turn coils is multiple, and at least two of the multi-turn coils are located at different heights.

9. The plasma etching apparatus as described in claim 7, characterized in that, The number of multi-turn coils is multiple, with at least two of the multi-turn coils wound along the axial direction of the base arranged radially along the base.

10. The plasma etching apparatus as described in claim 5, 6, 8, or 9, characterized in that, It also includes multiple power sources, each used to supply power to one of the coils.

11. The plasma etching apparatus as claimed in claim 10, characterized in that, The current magnitudes of at least two of the coils are different.

12. The plasma etching apparatus as claimed in claim 1, characterized in that, The surface of the coil has an insulating coating, which is at least one of polyimide or polytetrafluoroethylene.

13. The plasma etching apparatus as claimed in claim 1, characterized in that, The coil is housed within a protective tube that is coaxial with it; the protective tube is made of a non-magnetic material that is resistant to plasma corrosion.

14. The plasma etching apparatus as claimed in claim 13, characterized in that, The protective tube is made of aluminum alloy, and its surface has an aluminum oxide film obtained through anodizing.

15. A method for operating a plasma etching apparatus, characterized in that, Include: Provide a plasma etching apparatus as described in any one of claims 1 to 14; The wafer is placed on a substrate and subjected to plasma etching. Power is supplied to the coil to generate a magnetic field, which in turn generates a horizontal magnetic field component in the limiting ring, increasing the collision between charged particles and the sidewalls of the gas channel.

16. The method of operating the plasma etching apparatus as described in claim 15, characterized in that, Includes: Adjusting the current magnitude of the corresponding coil based on the coil's setting position.

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