Plasma processing equipment and plasma confinement ring thereof

Abstract

The invention discloses plasma processing equipment and a plasma confinement ring thereof, the plasma confinement ring is arranged between the periphery of a base and the side wall of a vacuum reaction cavity in a surrounding manner, the plasma confinement ring comprises an inner ring assembly, an outer ring assembly and an exhaust channel assembly connected with the inner ring assembly and the outer ring assembly respectively, the inner ring assembly is in contact with the periphery of the base, and the outer ring assembly is in contact with the side wall of the vacuum reaction cavity; the top of the inner ring assembly is flush with the top of the base, the outer ring assembly makes contact with the side wall of the vacuum reaction cavity, and the top surface of the exhaust channel assembly is lower than the top surface of the inner ring assembly. According to the invention, the risk of plasma leakage is reduced, the risk of arc discharge under high power is reduced, the corrosion of plasma to the protective coating coated on the surface of the plasma confinement ring is also reduced, and the equipment reliability is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a plasma processing device and a plasma confinement ring thereof. Background Art

[0002] In the process of processing a substrate by a plasma treatment device, the substrate is first fixedly placed in a plasma reaction chamber, and then radio frequency energy is transmitted into the plasma reaction chamber by a radio frequency power transmitting device to form a radio frequency electric field, and then various reaction gases are injected into the plasma reaction chamber. Under the action of the radio frequency electric field, the injected reaction gas is excited into a plasma state above the substrate, and finally chemical reactions and / or physical actions occur between the plasma and the substrate to form various characteristic structures, and volatile reaction products formed in the chemical reaction are separated from the surface of the etched material and are extracted out of the plasma reaction chamber by the vacuum system.

[0003] In order to prevent the reaction byproducts from carrying the plasma to areas outside the plasma processing area when they are discharged from the reaction chamber and causing damage to the area, a plasma confinement ring (FEIS Ring) is usually set between the base supporting the substrate and the side wall of the reaction chamber. The plasma confinement ring has multiple gas channels that penetrate the upper and lower surfaces of the confinement ring. The plasma confinement ring can ensure that when the plasma gas formed above the base flows through the confinement ring, all the charged particles in it are extinguished and become neutral gas flowing downward.

[0004] With the development of ultra-high aspect ratio etching in semiconductor manufacturing, high RF power is often required. The increase in RF power will make the density of plasma in the plasma processing area higher, which is prone to arc discharge and damage to the devices in the cavity. At the same time, the increase in RF power will make the energy of plasma higher, which is easy to cause plasma leakage when the plasma gas flows through the confinement ring.

[0005] The statements herein merely provide background art related to the present invention and do not necessarily constitute prior art. Summary of the invention

[0006] The object of the present invention is to provide a plasma processing device and a plasma confinement ring thereof, so as to reduce the risk of plasma leakage, reduce the risk of arc discharge under high power, reduce the corrosion of the protective coating coated on the surface of the plasma confinement ring by the plasma, and improve the reliability of the equipment.

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

[0008] Inner ring assembly;

[0009] an outer ring assembly surrounding the inner ring assembly;

[0010] An exhaust channel assembly is connected to the inner ring assembly and the outer ring assembly, wherein the top surface of the exhaust channel assembly is lower than the top surface of the inner ring assembly, and the exhaust channel assembly has a plurality of gas channels for discharging gas to an exhaust region below the plasma confinement ring.

[0011] The top of the exhaust passage assembly is connected to the bottom of the inner ring assembly and the bottom of the outer ring assembly.

[0012] The height of the exhaust channel component is less than or equal to the height of the inner ring component and the outer ring component.

[0013] The depth-to-width ratio of the gas channel is greater than or equal to 4:1.

[0014] The surface of the plasma confinement ring has a protective coating.

[0015] The material of the protective coating at least includes: an anodic oxide layer and yttrium oxide.

[0016] The exhaust channel assembly includes a plurality of concentrically arranged annular grid plates and at least one connecting rib, wherein the gas channel is formed between two adjacent annular grid plates, and the connecting rib is used to connect adjacent annular grid plates.

[0017] The plurality of concentrically arranged annular grid plates include: a first annular grid plate having a smallest diameter and a second annular grid plate having a largest diameter;

[0018] The plasma confinement ring further comprises:

[0019] a first connecting member, used to connect the inner ring assembly and the first annular grid plate;

[0020] The second connecting member is used to connect the outer ring assembly and the second annular grid plate.

[0021] The material of the plasma confinement ring at least includes: metal material.

[0022] The present invention also provides a plasma processing device, comprising:

[0023] Vacuum reaction chamber;

[0024] A gas shower head disposed on the top of the vacuum reaction chamber, the gas shower head serving as an upper electrode of the vacuum reaction chamber; a base located in the vacuum reaction chamber, used to support a substrate, the base being disposed opposite to the gas shower head, serving as a lower electrode of the vacuum reaction chamber;

[0025] The plasma confinement ring is disposed around the periphery of the pedestal and the side wall of the vacuum reaction chamber, and the exhaust area is below the plasma confinement ring. The plasma confinement ring comprises: an inner ring component, an outer ring component and an exhaust channel component. The inner ring component contacts the periphery of the pedestal, the top of the inner ring component is flush with the top of the pedestal, the outer ring component contacts the side wall of the vacuum reaction chamber, and the top surface of the exhaust channel component is lower than the top surface of the inner ring component.

[0026] The exhaust device is connected to the exhaust area in the vacuum reaction chamber and is used to exhaust the reaction by-products from the vacuum reaction chamber to maintain the vacuum environment of the vacuum reaction chamber.

[0027] A radio frequency power source is applied to the upper electrode or the lower electrode, and the total power of the radio frequency power source is greater than or equal to 10KW.

[0028] The plasma processing equipment further comprises:

[0029] A middle ground ring disposed below the plasma confinement ring, used to provide electric field shielding for the plasma confinement ring;

[0030] A lower grounding ring is arranged below the middle grounding ring, and the lower grounding ring is electrically connected to the middle grounding ring to form a radio frequency grounding loop in the vacuum reaction chamber.

[0031] The plasma confinement ring comprises a plurality of third connecting members, and the third connecting members are used to fix the outer ring assembly to the side wall of the vacuum reaction chamber.

[0032] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0033] The plasma confinement ring provided by the present invention comprises: an inner ring component, an outer ring component and an exhaust channel component arranged therebetween. Since the top surface of the exhaust channel component is arranged to be lower than the top surface of the inner ring component, the distance between the upper electrode in the plasma processing setting and the multiple gas channels in the plasma confinement ring is increased, and the space between the upper electrode and the gas channels is expanded, thereby reducing the radio frequency field strength between the upper electrode and the plasma confinement ring, thereby reducing the plasma density above the plasma confinement ring, and ultimately reducing the risk of plasma leakage, reducing the risk of arc discharge at high power, and reducing the corrosion of the protective coating coated on the surface of the plasma confinement ring by the plasma, thereby improving the reliability of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of a plasma processing device provided by the present invention.

[0035] Figure 2 The plasma confinement ring in one embodiment of the present invention is Figure 1 Schematic diagram of the structure of part A in .

[0036] Figure 3 The plasma confinement ring in another embodiment of the present invention is Figure 1 Schematic diagram of the structure of part A in . DETAILED DESCRIPTION

[0037] The following is based on Figure 1 to Figure 3 , specifically describe the preferred embodiments of the present invention.

[0038] like Figure 1As shown, the present invention provides a plasma processing device, which has a vacuum reaction chamber 1, and an opening 101 is arranged on the side wall of the reaction chamber for accommodating the entry and exit of substrates. A gas shower head 2 is arranged on the top of the vacuum reaction chamber 1, and the gas shower head 2 serves as the upper electrode of the vacuum reaction chamber 1. The gas shower head 2 is connected to an external gas supply device 3 and is used to transport reaction gas into the vacuum reaction chamber 1. A base 4 is arranged in the vacuum reaction chamber 1, and the base 4 is used to support a substrate 5 to be processed. The base 4 is arranged opposite to the gas shower head 2, and the base 4 serves as the lower electrode of the vacuum reaction chamber 1. One or more RF power sources 6 can be applied to the lower electrode 4 individually or simultaneously to the upper electrode 2 and the lower electrode 4, respectively, to deliver RF power to the lower electrode 4 or to the upper electrode 2 and the lower electrode 4, to generate a RF electric field between the upper electrode and the lower electrode, to dissociate the reaction gas into plasma, wherein the plasma contains a large number of active particles such as electrons, ions, excited atoms, molecules and free radicals, and the above-mentioned active particles can undergo a variety of physical and chemical reactions with the surface of the substrate to be processed, so that the morphology of the substrate surface changes, that is, the processing process is completed. A plasma confinement ring 7 is arranged around the periphery of the base 4 and the side wall of the vacuum reaction chamber 1, and the lower part of the plasma confinement ring 7 is an exhaust area, and the plasma confinement ring 7 is provided with a plurality of exhaust channels penetrating the upper and lower surfaces of the confinement ring. While the reaction gas is discharged through the exhaust channel, the plasma confinement ring 7 extinguishes the charged particles in the plasma, and the neutral gas flows downward, thereby preventing the inner wall of the reaction chamber and the exhaust pipe below the plasma confinement ring 7 from being polluted. A moving ring 8 is arranged at the periphery of the gas shower head 2. When the substrate is processed, the moving ring 8 descends to cover the opening 101. The plasma confinement ring 7 and the moving ring 8 jointly play a role in confining the plasma, confining the plasma in the reaction area between the upper and lower electrodes, and preventing the plasma from leaking into the non-reaction area and causing damage to the components in the non-reaction area. An exhaust device 9 is arranged below the vacuum reaction chamber 1, which is connected to the exhaust area in the vacuum reaction chamber 1 and is used to discharge the reaction by-products from the vacuum reaction chamber 1 to maintain the vacuum environment of the vacuum reaction chamber 1. A middle grounding ring 10 is arranged below the plasma confinement ring 7 to provide electric field shielding for the plasma confinement ring 7. A lower grounding ring 11 is arranged below the middle grounding ring 10, and the lower grounding ring 11 is electrically connected to the middle grounding ring 10 to form a radio frequency grounding loop in the vacuum reaction chamber 1.

[0039] The plasma processing equipment in this embodiment is applied to the etching process of ultra-high aspect ratio (aspect ratio greater than 40:1), and the RF power of the RF power supply needs to be increased, so that the total power of the RF power supply 6 is greater than or equal to 10KW. The increase of RF power will increase the field strength of the RF electric field between the upper electrode and the lower electrode. The increased RF field strength will promote the dissociation of the reaction gas into plasma, resulting in an increase in the plasma density in the space above the substrate 5 and the plasma confinement ring 7. In the process of plasma being discharged into the exhaust space through the plasma confinement ring 7, the plasma confinement ring 7 may not have time to extinguish all the charged particles in the plasma, which may cause the risk of plasma leakage to the lower exhaust device 9. This situation will not only damage the exhaust device 9, but also make the plasma in the reaction chamber unstable, thereby affecting the process results and increasing the possibility of damage to the substrate and equipment. In addition, the material of the plasma confinement ring 7 is usually made of metal material. In order to prevent the plasma confinement ring 7 from being corroded by the plasma, a protective coating is usually coated on the surface of the plasma confinement ring 7. The material of the protective coating can usually be an anodized layer or yttrium oxide, or other anti-corrosion materials. In the case of high field strength caused by high RF power, due to the higher density of plasma and higher ion energy, the sputtering and corrosion of the components in the reaction chamber are also enhanced. For the plasma confinement ring 7, the protective coating on its surface is more easily stripped off, thereby increasing the risk of arc discharge and plasma leakage.

[0040] In order to solve the above problems, Figure 1 and Figure 2As shown, a plasma confinement ring 7 provided by the present invention comprises an inner ring component 701 and an outer ring component 702, and an exhaust channel component 703 respectively connecting the inner ring component 701 and the outer ring component 702, wherein the inner ring component 701 contacts the periphery of the susceptor 4, the top of the inner ring component 701 is flush with the top of the susceptor 4, the outer ring component 702 surrounds the inner ring component 701, the outer ring component 702 contacts the side wall of the vacuum reaction chamber 1, and the outer ring component 702 is fixedly connected to the side wall of the vacuum reaction chamber 1 through a plurality of connectors 707. In addition, the top of the outer ring component 702 is substantially in contact with the bottom of the moving ring 8, so that the plasma is confined above the susceptor 4, and the plasma is prevented from contacting the side wall of the vacuum reaction chamber 1. The exhaust channel assembly 703 has a plurality of gas channels 704, and the gas channels 704 are used to discharge gas to the exhaust area below the plasma confinement ring 7. In this embodiment, the top surface of the exhaust channel assembly 703 is set to be lower than the top surface of the inner ring assembly 701. By setting the exhaust channel assembly 703 as a sunken structure, the distance between the upper electrode (gas shower head 2) and the plurality of gas channels 704 in the plasma confinement ring 7 is increased, and the space between the upper electrode and the gas channels 704 is expanded, thereby reducing the radio frequency field strength between the upper electrode and the plasma confinement ring 7, thereby reducing the plasma density above the plasma confinement ring 7, and finally reducing the risk of plasma leakage, reducing the risk of arc discharge at high power, and reducing the corrosion of the protective coating coated on the surface of the plasma confinement ring 7 by the plasma, thereby improving the reliability of the equipment.

[0041] like Figure 2 The exhaust channel assembly 703 comprises a plurality of concentrically arranged annular grid plates 705 and at least one connecting rib 706, wherein the gas channel 704 is formed between two adjacent annular grid plates 705, and the connecting rib 706 is used to connect adjacent annular grid plates 705. Among the plurality of concentrically arranged annular grid plates 705, a first annular grid plate 7051 having the smallest diameter is fixedly connected to the inner ring assembly 701 through a first connecting member 708, and a second annular grid plate 7052 having the largest diameter is fixedly connected to the outer ring assembly 702 through a second connecting member 709.

[0042] By increasing the distance between the top surface of the exhaust channel component 703 and the top surface of the inner ring component 701 as much as possible, that is, by increasing the sinking amount of the exhaust channel component 703 as much as possible, better plasma leakage prevention, arc discharge prevention and plasma corrosion prevention effects can be achieved. Figure 3As shown, in another embodiment of the invention, while ensuring that the distance between the plasma confinement ring 7 and the middle grounding ring 10 is sufficient, when the top of the exhaust channel assembly 703 is connected to the bottom of the inner ring assembly 701 and the bottom of the outer ring assembly 702, and the bottom of the exhaust channel assembly 703 does not touch the middle grounding ring 10 below to prevent interference with the electric field shielding in the vacuum reaction chamber, at this time, the top surface of the exhaust channel assembly 703 is almost flush with the bottom of the inner ring assembly 701, and the distance between the top surface of the exhaust channel assembly 703 and the top surface of the inner ring assembly 701 reaches a suitable value. That is, the distance between the upper electrode (gas shower head 2) and the multiple gas channels 704 in the plasma confinement ring 7 reaches the maximum value, and the space between the upper electrode and the gas channels 704 also expands to the maximum value, thereby minimizing the radio frequency field strength between the upper electrode and the plasma confinement ring 7, minimizing the plasma density above the plasma confinement ring 7, reducing the risk of plasma leakage, reducing the risk of arc discharge under high power, and reducing the corrosion of the protective coating coated on the surface of the plasma confinement ring 7 by the plasma, thereby maximizing the reliability of the equipment.

[0043] On the other hand, in order to facilitate the discharge of reaction by-products in deep holes, high aspect ratio etching processes often need to be carried out under lower chamber pressure (for example, less than 20mTorr), which requires the exhaust device 9 to have a sufficiently large exhaust capacity. The plasma confinement ring 7 is a major component that limits the flow conductance in the reaction chamber. In order to cooperate with the exhaust device 9 to quickly extract the remaining gas in the reaction chamber as quickly as possible, the usual practice is to consider widening the gas channel 704 on the plasma confinement ring 7 to facilitate the passage of gas as quickly as possible. However, after widening the gas channel 704, the risk of plasma leakage will increase. Therefore, a balance needs to be struck between the two according to actual conditions, and the size of the gas channel 704 on the plasma confinement ring 7 should be reasonably set. In this embodiment, the height of each annular grid plate 705 in the exhaust channel assembly 703 is less than or equal to the height of the inner ring assembly 701, and the height of each annular grid plate 705 in the exhaust channel assembly 703 is less than or equal to the height of the outer ring assembly 702. At the same time, the aspect ratio of the gas channel 704 is set according to actual conditions, and the aspect ratio of the gas channel 704 is usually set to be greater than 4:1. By reducing the aspect ratio of the gas channel 704 on the plasma confinement ring 7, the flow conductance in the reaction chamber is effectively increased, so that the reaction products are easier to extract and the accumulation of polymers is reduced.

[0044] It should be noted that, in the embodiments of the present invention, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0045] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A plasma confinement ring, characterized in that: Include: Inner ring assembly; an outer ring assembly surrounding the inner ring assembly; An exhaust channel assembly is connected to the inner ring assembly and the outer ring assembly, wherein the top surface of the exhaust channel assembly is lower than the top surface of the inner ring assembly, and the exhaust channel assembly has a plurality of gas channels for discharging gas to an exhaust region below the plasma confinement ring.

2. The plasma confinement ring according to claim 1, characterized in that: The top of the exhaust passage assembly is connected to the bottom of the inner ring assembly and the bottom of the outer ring assembly.

3. The plasma confinement ring according to claim 2, characterized in that: The height of the exhaust channel component is less than or equal to the height of the inner ring component and the outer ring component.

4. The plasma confinement ring according to claim 3, characterized in that: The depth-to-width ratio of the gas channel is greater than or equal to 4:

1.

5. The plasma confinement ring according to claim 1, wherein: The surface of the plasma confinement ring has a protective coating.

6. The plasma confinement ring according to claim 5, characterized in that: The material of the protective coating at least includes: an anodic oxide layer and yttrium oxide.

7. The plasma confinement ring according to claim 1, wherein: The exhaust channel assembly includes a plurality of concentrically arranged annular grid plates and at least one connecting rib, wherein the gas channel is formed between two adjacent annular grid plates, and the connecting rib is used to connect adjacent annular grid plates.

8. The plasma confinement ring according to claim 7, characterized in that The plurality of concentrically arranged annular grid plates include: a first annular grid plate having a smallest diameter and a second annular grid plate having a largest diameter; The plasma confinement ring further comprises: a first connecting member, used to connect the inner ring assembly and the first annular grid plate; The second connecting member is used to connect the outer ring assembly and the second annular grid plate.

9. The plasma confinement ring according to claim 1, wherein: The material of the plasma confinement ring at least includes: metal material.

10. A plasma processing device, characterized in that: Include: Vacuum reaction chamber; A gas shower head disposed on the top of the vacuum reaction chamber, the gas shower head serving as an upper electrode of the vacuum reaction chamber; a base located in the vacuum reaction chamber, used to support a substrate, the base being disposed opposite to the gas shower head, serving as a lower electrode of the vacuum reaction chamber; The plasma confinement ring according to any one of claims 1 to 9, wherein the plasma confinement ring is disposed between the periphery of the susceptor and the side wall of the vacuum reaction chamber, and an exhaust region is provided below the plasma confinement ring. The plasma confinement ring comprises: an inner ring component, an outer ring component, and an exhaust channel component, wherein the inner ring component contacts the periphery of the susceptor, the top of the inner ring component is flush with the top of the susceptor, the outer ring component contacts the side wall of the vacuum reaction chamber, and the top surface of the exhaust channel component is lower than the top surface of the inner ring component; The exhaust device is connected to the exhaust area in the vacuum reaction chamber and is used to exhaust the reaction by-products from the vacuum reaction chamber to maintain the vacuum environment of the vacuum reaction chamber.

11. The plasma processing equipment according to claim 10, characterized in that: A radio frequency power source is applied to the upper electrode or the lower electrode, and the total power of the radio frequency power source is greater than or equal to 10KW.

12. The plasma processing equipment according to claim 10, characterized in that: The plasma processing equipment further comprises: A middle ground ring disposed below the plasma confinement ring, used to provide electric field shielding for the plasma confinement ring; A lower grounding ring is arranged below the middle grounding ring, and the lower grounding ring is electrically connected to the middle grounding ring to form a radio frequency grounding loop in the vacuum reaction chamber.

13. The plasma processing equipment according to claim 10, characterized in that: The plasma confinement ring comprises a plurality of third connecting members, and the third connecting members are used to fix the outer ring assembly to the side wall of the vacuum reaction chamber.

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