Plasma etching device and working method

Abstract

The invention provides a plasma etching device which comprises the components of a reaction chamber which is internally provided with a base; the limiting ring is arranged around the periphery of the base, and the limiting ring is provided with a plurality of gas channels; the middle grounding ring and the lower grounding ring are arranged on the periphery of the base and extend along the radial direction and the axial direction of the base respectively; the middle grounding ring is connected with the lower grounding ring and the side wall of the reaction cavity; the bottom of the lower grounding ring is connected with the bottom wall of the reaction cavity; a radio frequency shielding area enclosed by the outer part of the lower grounding ring, the lower part of the middle grounding ring and the reaction cavity is arranged in the reaction cavity; the at least one coil is arranged in the radio frequency shielding area around the lower grounding ring; the coil generates a magnetic field component in the horizontal direction at the position of the limiting ring, and the magnetic field component is used for limiting charged particles discharged from the plasma reaction area from flowing into the exhaust area through the gas channel. The invention further provides a working method of the plasma etching device. According to the invention, the air exhaust efficiency can be improved, enough electron and ion wall collision rate is ensured, and the risk of plasma leakage is reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor equipment, and in particular to a plasma etching device and a working method. Background Art

[0002] During the plasma etching process, various process gases are injected into the reaction chamber of the plasma etching device and excited into plasma (including electrons, ions, and active free radicals) under the action of the radio frequency electric field in the reaction chamber. The reaction between the plasma and the wafer produces by-products, which need to be removed in time to ensure the smooth progress of the etching reaction. Therefore, the plasma etching devices currently used all use a flowing gas reaction chamber, that is, the reaction gas is continuously injected from one end of the reaction chamber, and the by-products and other unreacted substances after the reaction are continuously removed from the other end by a vacuum pump.

[0003] During the vacuuming process, the plasma needs to be quenched to avoid plasma erosion of the vacuum pump and the vacuum pipe, as well as possible plasma conduction leading to radio frequency leakage. The commonly used quenching device is a multi-layer stacked annular plasma confinement ring (FEIS Ring), which is arranged around the lower electrode, so that it can neither limit the plasma reaction space nor block the film transmission port. The confinement ring relies on the narrow ring spacing (usually 1.5mm) and the larger ring plate height (17.4mm) to increase the probability of electrons and ions hitting the wall, so that most electrons and ions will encounter wall losses on the ring plate, thereby achieving the purpose of quenching the plasma. However, the cost of this design is that the exhaust gas path is divided into many narrow gaps by a dozen to dozens of ring plates, resulting in greatly limited flow conductance of the exhaust gas path, and it is impossible to achieve an atmospheric flow and low pressure working environment.

[0004] In plasma etching with a feature size (CD critical dimension) less than 10nm, such as etching of small holes of BARC (Bottom Anti-Reflective Coatings), the BARC in the small hole can easily remain at the bottom of the hole, affecting the subsequent process. The residue of BARC at the bottom of the hole is due to the very small feature size, which makes it more difficult to enter the process gas and extract the by-products. In order to improve the entry of process gases and the extraction of by-products, a process regime that makes the pressure in the reaction chamber lower and the gas flow larger will be used, so the conductance of the exhaust needs to be improved.

[0005] Based on the current process, there are only two ways to improve conductance: reducing the height of the ring plate (the distance between the upper and lower surfaces of the ring plate) or increasing the distance between the ring plates. Either way will reduce the electron and ion wall collision rate, bringing the risk of plasma leakage. How to improve the conductance of the pumping gas while ensuring sufficient electron and ion wall collision rate and reducing the risk of plasma leakage is a problem that needs to be solved urgently. Summary of the invention

[0006] The purpose of the present invention is to provide a plasma etching device and a working method, which generates a horizontal magnetic field component at the location of the confinement ring through a coil arranged in the radio frequency shielding area, thereby ensuring that the electrons and ions discharged from the plasma reaction area have a sufficient wall collision rate, thereby reducing the risk of plasma leakage. Since the coil is arranged in a non-radio frequency environment, the use effect and service life of the coil are guaranteed, and there is no need to worry about the radio frequency energy leaking to the outside of the reaction chamber through the power cord of the coil. In addition, the ring plates of the confinement ring can have a larger plate spacing, which greatly improves the air conduction of the exhaust gas and can meet the process requirements of large flow and low pressure.

[0007] In order to achieve the above object, the present invention provides a plasma etching device, comprising:

[0008] A reaction chamber, in which a base is arranged;

[0009] a confinement ring disposed around a periphery of the susceptor, the confinement ring having a plurality of gas passages;

[0010] A middle grounding ring and a lower grounding ring are arranged on the periphery of the base, and extend radially and axially respectively; the middle grounding ring connects the lower grounding ring and the side wall of the reaction chamber, and the bottom of the lower grounding ring connects the bottom wall of the reaction chamber; a radio frequency shielding area is provided in the reaction chamber, and the radio frequency shielding area is surrounded by the outside of the lower grounding ring, the bottom of the middle grounding ring and the reaction chamber;

[0011] At least one coil is arranged around the lower grounding ring in the radio frequency shielding area; the horizontal magnetic field component generated by the coil at the position where the limiting ring is located is used to limit the charged particles discharged from the plasma reaction area to flow into the exhaust area through the gas channel.

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

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

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

[0015] Optionally, there are multiple single-turn coils, and at least two of the single-turn coils are arranged radially along the base.

[0016] Optionally, there are multiple single-turn coils, and at least two of the single-turn coils are arranged along the axial direction of the base.

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

[0018] Optionally, there are multiple multi-turn coils, and at least two of the multi-turn coils are located at different heights.

[0019] Optionally, there are multiple multi-turn coils, and at least two of the multi-turn coils wound along the axial direction of the base are arranged along the radial direction of the base.

[0020] Optionally, the plasma etching device further includes a plurality of power supplies, each for supplying power to the plurality of coils.

[0021] Optionally, the currents of at least two of the coils are different in magnitude.

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

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

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

[0025] The present invention also provides a working method of a plasma etching device, comprising:

[0026] Providing a plasma etching device according to the present invention;

[0027] The wafer is placed on a susceptor and a plasma etching process is performed;

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

[0029] Optionally, the working method of the plasma device further comprises:

[0030] Based on the setting position of the coil, the current size of the corresponding coil is adjusted.

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

[0032] 1) In the plasma etching device of the present invention, the outside of the lower grounding ring, the bottom of the middle grounding ring and the reaction chamber form a radio frequency shielding area, and a coil is arranged in the radio frequency shielding area. The coil generates a horizontal magnetic field component (hereinafter referred to as the horizontal magnetic field component) at the position of the limiting ring, so as to ensure that the charged particles discharged from the plasma reaction area have a sufficient wall collision rate, limit the plasma from being discharged into the exhaust area through the gas channel, and reduce the risk of plasma leakage. In addition, the ring plates of the limiting ring can have a larger plate spacing, which greatly improves the gas conduction of the exhaust gas and can meet the process requirements of large flow and low pressure.

[0033] 2) By adjusting the number of turns of the coil, the height of the coil, the number of coils used, etc., a horizontal magnetic field component of sufficient strength can be provided between any two adjacent ring plates, so that a larger gap can be provided between any two adjacent ring plates, greatly improving the extraction efficiency. The present invention can also dynamically adjust the horizontal magnetic field component at the location of the limiting ring by adjusting the current of the coil in real time, and only a small current needs to be provided to the coil to ensure the wall collision rate of the charged particles, avoiding the potential safety hazard caused by overheating of the coil due to excessive current of the coil, and further ensuring the safety of wafer processing.

[0034] 3) Even if the coil works in the high temperature environment of the reaction chamber for a long time, it can continuously and stably generate the required magnetic field without worrying about the confinement ring losing its confinement effect on the plasma. Since the coil is set in a non-RF environment, there is no need to worry about the RF energy leaking to the outside of the reaction chamber through the power cord of the coil without using filtering equipment, which improves the safety of wafer processing while reducing economic costs. The gas in the RF shielding area only contains electrically neutral free radicals and reaction by-products, so the coil will not be corroded by plasma, and has better use effect and longer 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, thereby improving the uniformity of the plasma distribution in the reaction chamber.

[0036] 5) The present invention does not need to change the layout of existing components in the reaction chamber, and the installation and adjustment of the coil are quick and convenient, and has good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the description. Obviously, the drawings described below are an embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

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

[0039] Figure 2 is a schematic diagram of a plasma etching device in Example 1;

[0040] Figure 3 This is a schematic diagram of a charged particle being deflected by the Lorentz force in the first embodiment;

[0041] Figure 4 This is a schematic diagram of a second embodiment in which two single-turn coils arranged radially along the base are provided in the reaction chamber;

[0042] Figure 5 This is a schematic diagram of a second embodiment in which two single-turn coils arranged along the axial direction of the base are provided in the reaction chamber;

[0043] Figure 6 is a schematic diagram of another embodiment in which at least two of the multiple single-turn coils arranged along the radial direction of the base are located at different heights;

[0044] Figure 7 , Figure 8 They are schematic diagrams of the multi-turn coil winding around the central axis of the base along the axial direction and radial direction of the base in the third embodiment;

[0045] Fig. 9 is a schematic diagram of two multi-turn coils located at different heights in another embodiment;

[0046] Fig.10 is a schematic diagram of another embodiment in which two multi-turn coils wound along the axial direction of the base are arranged along the radial direction of the base;

[0047] Fig.11 The figure is a flow chart of the working method of the plasma etching device in the present invention. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0050] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0051] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0052] As used in this specification and the appended claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" may be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0053] In addition, in the description of the present application, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0054] Figure 1 A plasma etching device 1 is shown, which has a reaction chamber 10, which is substantially cylindrical and has substantially vertical side walls. A gas shower head 110 and a base 120 are arranged opposite to each other in the reaction chamber 10, which serve as an upper electrode and a lower electrode of the reaction chamber 10, respectively. Generally, the area between the upper electrode and the lower electrode is a plasma reaction area A, which will form high-frequency energy to ignite and maintain plasma.

[0055] The base 131 is used to place the wafer to be processed. The reaction gas is input into the reaction chamber 10 from the gas shower head 110, and one or more RF power supplies can be applied to the lower electrode alone or to the upper electrode and the lower electrode at the same time, so as to transmit the RF power to the lower electrode or the upper electrode and the lower electrode, thereby generating a large electric field inside the reaction chamber 10. Most of the electric field is contained in the plasma reaction area A between the upper electrode and the lower electrode. This electric field accelerates a small amount of electrons present in the reaction chamber 11, causing them to collide with the gas molecules of the input reaction gas. These collisions lead to the ionization of the reaction gas and the excitation of the plasma, thereby generating plasma in the reaction chamber 10. The plasma contains a large number of active particles such as electrons, ions, excited atoms, molecules and free radicals. The above active particles can undergo various physical and chemical reactions with the surface of the wafer to be processed, so that the morphology of the wafer surface changes, that is, the etching process is completed.

[0056] The confinement ring 130 surrounds the susceptor 120 and is disposed between the plasma reaction region A and the exhaust region C. The reaction gas and byproduct gas used in the etching process enter the exhaust region C through the gap between the ring plates 131 of the confinement ring 130, and are pumped out to the outside of the reaction chamber 10 through an exhaust device (such as a vacuum pump, not shown in the figure) connected to the exhaust region C. After the plasma in the gas enters the confinement ring 130, the charged particles collide with the side wall of the ring plate 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.

[0057] In the plasma etching process with a feature size less than 10nm, we need to increase the conductance of the pumping gas to establish a lower gas pressure in the reaction chamber 10, which will facilitate the extraction of reaction byproducts and reduce the deposition of reaction byproducts on the wafer. Based on the current process, there are only two ways to increase the conductance: reducing the height of the ring plate or increasing the distance between the ring plates, either of which will reduce the rate of electrons and ions hitting the wall, bringing the risk of plasma leakage.

[0058] The present invention provides a plasma etching device and method, which can improve the gas conduction of the exhaust gas while ensuring a sufficient electron and ion wall collision rate and reducing the risk of plasma leakage.

[0059] Embodiment 1

[0060] Figure 2 The plasma etching device 2 in this embodiment is shown, which includes a reaction chamber 20, and a wafer transfer port (not shown in the figure) is provided on the side wall of the reaction chamber. The reaction chamber 20 is provided with: a gas shower 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 in the figure).

[0061] like Figure 2 As shown, the confinement ring 230 is arranged around the periphery of the susceptor 220 and avoids the wafer transfer port on the side wall of the reaction chamber, so as not to affect the transfer of the wafer. The confinement ring 230 includes a plurality of concentrically arranged ring plates 231, which are arranged along the radial direction of the susceptor 220, and the gap between two adjacent ring plates 231 forms a gas channel, through which the reaction byproducts in the plasma reaction area A flow into the exhaust area C.

[0062] like Figure 2 As shown, the middle grounding ring 240 and the lower grounding ring 250 are arranged on the periphery of the base 220, and extend radially and axially of the base 220 respectively. The middle grounding ring 240 connects the lower grounding ring 250 and the side wall of the reaction chamber. The bottom of the lower grounding ring 250 is connected to the bottom wall of the reaction chamber. The middle grounding ring 240 and the lower grounding ring 250 are made of conductors, and the middle grounding ring 240 and the lower grounding ring 250 are electrically connected to form a radio frequency grounding loop in the reaction chamber. The confinement ring 230 is at a suspended potential, the middle grounding ring 240 is at a zero potential, and the transmission of radio frequency electric power between the middle grounding ring 240 and the confinement ring 230 is achieved by capacitive coupling (no DC conduction). In this way, the radio frequency energy can be shielded above the middle grounding ring 240, the generation of secondary plasma can be avoided, and the accumulated charge on the confinement ring 230 can be guided away. It is easy to understand that a radio frequency shielding area is surrounded by the outside of the lower grounding ring 250, the bottom of the middle grounding ring 240 and the reaction chamber 20.

[0063] The coil 260 is arranged in the radio frequency shielding area around the lower grounding ring 250. In a preferred embodiment, the coil 260 is coaxial with the base 220. The horizontal magnetic field component (hereinafter referred to as the horizontal magnetic field component) generated by the coil 260 at the location of the confinement ring is used to restrict the charged particles discharged from the plasma reaction area A to flow into the exhaust area C through the gas channel, thereby ensuring the plasma confinement efficiency while increasing the gap width.

[0064] Even if the coil 260 works in a high temperature environment in the reaction chamber for a long time, it can continuously and stably generate the required magnetic field, and there is no need to worry that the confinement ring 230 loses its confinement effect on the plasma. The present invention does not need to change the layout of existing components in the reaction chamber 20, and the installation and adjustment of the coil 260 are quick and convenient, which has good practicality.

[0065] Since the reaction chamber 20 of the plasma etching device 2 uses radio frequency as the power source of the plasma, the radio frequency electric field is distributed in most of the space in the reaction chamber 20, and the radio frequency current will also propagate along the metal surface of the inner wall of the reaction chamber. In the present invention, the coil 260 is arranged in the radio frequency shielding area, and the gas in the radio frequency shielding area only contains electrically neutral free radicals and reaction by-products, so the coil 260 will not be affected by the plasma and the radio frequency electric field, and has a better use effect and a longer service life. Even if the coil 260 is not equipped with a filtering device (usually large in size and cumbersome to use), there is no need to worry about the radio frequency energy leaking to the outside of the reaction chamber 20 through the power cord of the coil 260, which improves the safety of wafer processing while greatly reducing the economic cost.

[0066] In a preferred embodiment, the coil 260 is disposed in a protective tube coaxial with the coil 260, the protective tube is made of a non-magnetic material (such as an aluminum alloy) that is resistant to plasma corrosion, the surface of the protective tube has an aluminum oxide film obtained by anodizing, and the surface of the coil 260 has an insulating coating (such as at least one of polyimide and polytetrafluoroethylene). The protective tube and the insulating coating further protect the coil 260 from the adverse effects of plasma and radio frequency electric fields.

[0067] In this embodiment, the number of coils 260 is 1, and the number of coils 260 can be set according to actual needs. In this embodiment, a single-turn coil is used, and in other embodiments, a multi-turn coil can also be used. In the present invention, there is no restriction on the number, number of turns, height, diameter, and current size of coils 260, as long as the conductance of confinement ring 230 and the plasma confinement efficiency can be improved.

[0068] like Figure 3 As shown in the figure represents the horizontal magnetic field component at the location of the confinement ring. Indicates the velocity of charged particles entering the gas channel. Charged particles are deflected by the Lorentz force F in this horizontal magnetic field component (the velocity becomes ), moves along the spiral trajectory and finally collides with the side wall of the ring plate 231. Therefore, the charged particles in the plasma pass through the confinement ring 230 relatively directly and move toward the side wall of the ring plate more easily. Through this horizontal magnetic field component, the confinement capacity of each gap on the plasma is improved, so the width of each gap can be appropriately increased, and the pumping efficiency of the confinement ring 230 is effectively improved.

[0069] Affected by the airflow in the confinement ring 230, the flow direction of electrons and ions in the gas channel is mainly from top to bottom, and will not be affected by the vertical magnetic induction lines. Therefore, the vertical magnetic field component (referred to as the vertical magnetic field component) at the location of the confinement ring is not very helpful in improving the wall collision rate of charged particles. We hope to increase the horizontal magnetic field component of the coil 260 at the location of the confinement ring to increase the plasma wall collision rate.

[0070] The horizontal magnetic field component is affected by two factors: magnetic field strength and magnetic field direction. The greater the magnetic field strength, the greater the horizontal magnetic field component. The closer the magnetic field direction is to the horizontal, the greater the horizontal magnetic field component. By increasing the vertical distance between the 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 the coil 260 and the limiting ring 230, the smaller the magnetic field strength generated by the coil 260 at the location of the limiting ring. By adjusting the height of the coil 260, we can achieve a balance between the magnetic field strength and the magnetic field direction, so that the coil 260 has a larger horizontal magnetic field component at the location of the limiting ring. It should be emphasized that even after the coil 260 is installed and fixed, the present invention can also dynamically adjust the horizontal magnetic field component at the location of the limiting ring by adjusting the current size of the coil 260 in real time, effectively ensuring the wall collision rate of charged particles.

[0071] like Figure 2 As shown, in this embodiment, the limiting ring 230 is divided into an inner region 230a and an outer region 230b along the radial direction of the limiting ring 230. Although the inner region 230a close 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 intensity of the inner region 230a is larger. 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 lines of force of the outer region 230b are approximately horizontal, and the magnetic field strength of the outer region 230b gradually decreases from the inside to the outside (the distribution of the magnetic induction lines gradually becomes sparse), so the strength of the horizontal magnetic field component of the outer region 230b also gradually decreases from the inside to the outside. In summary, the strength of the horizontal magnetic field component at the location of the confinement ring is generally shown as gradually decreasing 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).

[0072] The present invention only needs a relatively small current to generate a horizontal magnetic field component of sufficient strength at the location of the confinement ring, thereby ensuring the confinement efficiency of the plasma, reducing the height of the ring plate, and improving the air conduction of the confinement ring 230. While saving energy, it can also prevent the coil 260 from overheating due to excessive current provided to the coil 260, thereby effectively ensuring the safety of wafer processing.

[0073] On the other hand, Figure 2 As shown, within the range where the radial distance from the central axis of the base 220 is less than r (r is the radius of the coil 260), the coil 260 mainly generates a vertical magnetic field. The magnetic field The Lorentz force is generated on the electrons in the plasma (which can be used for ionization collisions). The trajectory of the electrons is deflected by the Lorentz force, and the straight-line motion of the electrons is changed to a magnetic field. The spiral motion of the magnetic induction lines is equivalent to increasing the movement path of electrons and increasing the collision probability between electrons and gas molecules. Therefore, it can further increase the residence time and density of the plasma in the reaction chamber, thereby improving the uniformity of plasma distribution in the reaction chamber and the etching efficiency.

[0074] Embodiment 2

[0075] like Figure 4 As shown, in this embodiment, two single-turn coils 360a and 360b are arranged radially along the base 320 in the radio frequency shielding area. The coils 360a and 360b are coaxial with the base 320, and the diameter of the coil 360b is greater than the diameter of the coil 360a. It has been explained in the previous embodiment that under the action of the coil 360a alone, the horizontal magnetic field component of the outer area 330b is stronger than the horizontal magnetic field component of the inner area 330a. In this embodiment, the radius R of the coil 360b is substantially the same as the outer diameter of the inner area 330a. Figure 4 Only the magnetic lines of force of coil 360b are shown. Coil 360b mainly generates a vertical magnetic field within a range where the radial spacing from the central axis of the base is less than R, and has 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 relatively large, and can generate a relatively strong horizontal magnetic field component to compensate for the deficiency of the horizontal magnetic field component generated by coil 360a in the outer region 330b. Compared with the first embodiment, the gap width of the outer region 330b can be further appropriately increased, thereby further improving the conductance of the confinement ring 330.

[0076] In another embodiment, at least three coils 360 are arranged radially along the base 320 in the radio frequency shielding area. It should be emphasized that in the present invention, 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, each gap 360 can have a horizontal magnetic field component with approximately the same strength, and the width of each gap is approximately the same. Since each gap has a large conductance, the pumping efficiency of the confinement ring 330 is further improved.

[0077] like Figure 5 As shown, in another embodiment, the single-turn coils 360a and 360b are arranged along the axial direction of the base 320 to enhance the horizontal magnetic field component where the confinement ring is located. In the radial direction of the confinement ring 330, the intensity gradient of the horizontal magnetic field component is relatively large. Compared with the first embodiment, the width of each gap can be further appropriately increased, and the gap close to the base 320 has a larger width than the gap far from the base 320.

[0078] like Figure 6 As shown, in another embodiment, a plurality of single-turn coils 360 ( Figure 6 3 are shown in the figure) arranged along the radial direction of the base 320, and at least two of the single-turn coils 360 have different heights. In this way, not only can the horizontal magnetic field component at the location of the confinement ring be enhanced as a whole, but also the intensity gradient of the horizontal magnetic field component can be smaller in the radial direction of the confinement ring 330, the width difference of different gaps is smaller, and each gap has a larger conductance.

[0079] Embodiment 3

[0080] In order to further increase the horizontal magnetic field component at the location of the confinement ring, a multi-turn coil 460 is used in this embodiment.

[0081] Figure 7 , Figure 8 The multi-turn coil 460 in the embodiment is respectively wound around the central axis of the base 420 in the axial direction and radial direction of the base 420. Along the radial direction of the limiting ring 430, from inside to outside, Figure 7 , Figure 8 The intensity of the horizontal magnetic field components decreases, and the width of the gap also decreases. Figure 7 , Figure 8 In the example above, the width of each gap can be increased appropriately. Figure 7 compared to, Figure 8 The intensity gradient of the horizontal magnetic field component is small.

[0082] In another embodiment, Fig. 9 As shown, two multi-turn coils 460 (the number of coils is only for example and is not a limitation of the present invention) are located at different heights. Figure 5 The purpose is to enhance the horizontal magnetic field component where the confinement ring is located. Since the multi-turn coil 460 can generate a larger magnetic field, it is obvious that this embodiment is better than Figure 5 The effect is better.

[0083] In another embodiment, Fig.10 As shown, at least two multi-turn coils 460 wound along the axial direction of the base 420 are arranged along the radial direction of the base 420. The purpose of this embodiment is similar to Figure 4 The purpose is to enhance the horizontal magnetic field component at the location of the limiting ring 430 as a whole, and at the same time, to reduce the intensity gradient of the horizontal magnetic field component in the radial direction of the limiting ring 430, so that each gap of the limiting ring 430 has a larger conductance. Since the multi-turn coil 460 can generate a larger magnetic field, it is obvious that this embodiment is better than Figure 4 The effect is better.

[0084] In some embodiments, single-turn coils and multi-turn coils may be used simultaneously in the reaction chamber, as long as the plasma confinement efficiency and conductance of the confinement ring can be improved, which is not limited in the present invention.

[0085] The present invention also provides a working method of a plasma etching device, such as Fig.11 As shown, including:

[0086] Step S1, providing a plasma etching device as described in the present invention;

[0087] Step S2, placing the wafer on a base and performing a plasma etching process;

[0088] Step S3, supplying power to the coil to generate a magnetic field, and through the horizontal magnetic field component generated by the magnetic field at the position of the confinement ring, limiting the charged particles discharged from the plasma reaction area to flow into the exhaust area through the gas channel of the confinement ring.

[0089] In one embodiment, the working method of the plasma etching device further comprises:

[0090] Based on the setting position of the coil, the current size of the corresponding coil is adjusted.

[0091] For example, when the vertical distance between the coil and the confinement ring is small, the vertical magnetic field component at the location of the confinement ring is large and the horizontal magnetic field component is small, and the current of the coil can be appropriately increased. Alternatively, for multiple coils arranged along the radial direction of the base, the current of the multiple coils is gradually reduced from the inside to the outside, so that the horizontal magnetic field components between the gaps of the confinement ring are approximately the same, the widths of the gaps are approximately the same, and the confinement ring has a uniform conductance.

[0092] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean 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 the present application.

[0093] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A plasma etching device, characterized in that: include: a reaction chamber, in which a base is arranged; a confinement ring disposed around a periphery of the susceptor, the confinement ring having a plurality of gas passages; A middle grounding ring and a lower grounding ring are arranged on the periphery of the base and extend along the radial direction and axial direction of the base respectively; The middle grounding ring connects the lower grounding ring and the side wall of the reaction chamber, and the bottom of the lower grounding ring connects the bottom wall of the reaction chamber; the reaction chamber has a radio frequency shielding area, and the radio frequency shielding area is surrounded by the outside of the lower grounding ring, the bottom of the middle grounding ring and the reaction chamber; At least one coil is arranged around the lower grounding ring in the radio frequency shielding area; the horizontal magnetic field component generated by the coil at the position where the limiting ring is located is used to limit the charged particles discharged from the plasma reaction area to flow into the exhaust area through the gas channel.

2. The plasma etching device according to claim 1, characterized in that: The limiting ring includes a plurality of concentrically arranged ring plates, the plurality of ring plates are arranged along the radial direction of the base, and the gap between two adjacent ring plates forms the gas channel.

3. The plasma etching device according to claim 1, characterized in that: Along the radial direction of the confinement ring, from inside to outside, the width of the gas channel decreases.

4. The plasma etching device according to claim 1, characterized in that: The coil is a single-turn coil, and the single-turn coil and the base have the same central axis.

5. The plasma etching device according to claim 4, characterized in that: There are multiple single-turn coils, and at least two of the single-turn coils are arranged along the radial direction of the base.

6. The plasma etching device according to claim 4, characterized in that: There are multiple single-turn coils, and at least two of the single-turn coils are arranged along the axial direction of the base.

7. The plasma etching device according to claim 1, characterized in that: The coil is a multi-turn coil, and the multi-turn coil is wound around the central axis of the base along the axial direction or the radial direction of the base.

8. The plasma etching device according to claim 7, characterized in that: There are multiple multi-turn coils, and at least two of the multi-turn coils are located at different heights.

9. The plasma etching device according to claim 7, characterized in that: The number of the multi-turn coils is plural, and at least two of the multi-turn coils wound along the axial direction of the base are arranged along the radial direction of the base.

10. The plasma etching device according to any one of claims 5, 6, 8 and 9, characterized in that: It also includes multiple power supplies, which are used to supply power to the multiple coils respectively.

11. The plasma etching device according to claim 10, characterized in that: The currents of at least two of the coils are different in magnitude.

12. The plasma etching device according to claim 1, characterized in that: The surface of the coil has an insulating coating, and the insulating coating is at least one of polyimide and polytetrafluoroethylene.

13. The plasma etching device according to claim 1, characterized in that: The coil is arranged in a protective tube coaxial with the coil; the protective tube is made of a non-magnetic material that is resistant to plasma corrosion.

14. The plasma etching device according to claim 13, characterized in that: The protection tube is made of aluminum alloy, and the surface of the protection tube has an aluminum oxide film obtained by anodizing.

15. A method for operating a plasma etching device, characterized in that: Include: Providing a plasma etching device as claimed in any one of claims 1 to 14; The wafer is placed on a susceptor and a plasma etching process is performed; The coil is powered to generate a magnetic field, and the horizontal magnetic field component generated by the magnetic field at the location of the confinement ring restricts charged particles discharged from the plasma reaction region from flowing into the exhaust region through the gas channel of the confinement ring.

16. The operating method of the plasma etching device according to claim 15, characterized in that: Including: Based on the setting position of the coil, adjusting the current size of the corresponding coil.

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