Plasma processing apparatus and its plasma confinement ring

Abstract

A plasma processing apparatus and a plasma confinement ring thereof, the plasma confinement ring is disposed between a periphery of a susceptor and a sidewall of a vacuum reaction chamber, the plasma confinement ring comprises an inner ring assembly, an outer ring assembly and an exhaust passage assembly connecting the inner ring assembly and the outer ring assembly, the inner ring assembly is in contact with the periphery of the susceptor, a top of the inner ring assembly is flush with a top of the susceptor, the outer ring assembly is in contact with the sidewall of the vacuum reaction chamber, a top surface of the exhaust passage assembly is lower than a top surface of the inner ring assembly. The present application reduces the risk of plasma leakage, reduces the risk of arc discharge at high power, reduces the corrosion of the protective coating coated on the surface of the plasma confinement ring by the plasma, and improves the reliability of the apparatus.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor, and in particular to a plasma confinement ring of a plasma processing apparatus. BACKGROUND

[0002] In the process of processing a substrate by a plasma processing apparatus, the substrate is first fixedly placed in a plasma reaction chamber, then a radio frequency energy is emitted into the plasma reaction chamber by a radio frequency power emitting device to form a radio frequency electric field, then various reaction gases are injected into the plasma reaction chamber, and the injected reaction gases are excited into a plasma state above the substrate under the action of the radio frequency electric field, finally a chemical reaction and / or a physical action occur between the plasma and the substrate to form various feature structures, and volatile reaction products formed in the chemical reaction are separated from the surface of the etching material and are extracted out of the plasma reaction chamber by a vacuum extraction system.

[0003] To avoid that the reaction byproducts carry the plasma out of the plasma processing region when being discharged from the reaction chamber to cause damage to the region, a plasma confinement ring, i.e. a FEIS Ring (Flow Equalizing Ion Shield Ring), is usually arranged between a substrate support and the sidewall of the reaction chamber. The plasma confinement ring has a plurality of gas passages penetrating through the upper and lower surfaces of the confinement ring, and the plasma confinement ring can ensure that all the charged particles in the plasma gas formed above the substrate support are extinguished when flowing through the confinement ring, and the neutral gas flows downward.

[0004] With the development of ultra-high aspect ratio etching in semiconductor manufacturing, high radio frequency power is often required, and the increase of the radio frequency power will result in higher density of the plasma in the plasma processing region, which is easy to cause arc discharge and damage to the devices in the chamber, and the increase of the radio frequency power will also result in higher energy of the plasma, which is easy to cause plasma leakage when the plasma gas flows through the confinement ring.

[0005] The statements herein merely provide background information related to the present application and do not necessarily constitute the prior art. SUMMARY

[0006] The present application aims to provide a plasma processing apparatus 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 plasma to the protective coating coated on the surface of the plasma confinement ring, and improve the reliability of the apparatus.

[0007] To achieve the above-mentioned purpose, the present application provides a plasma confinement ring, comprising:

[0008] an inner ring assembly;

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

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

[0011] a top of the exhaust channel assembly is connected with a bottom of the inner ring assembly and a bottom of the outer ring assembly.

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

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

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

[0015] a material of the protective coating at least includes: an anodization layer, yttrium oxide.

[0016] the exhaust channel assembly includes a plurality of concentrically arranged ring-shaped gratings and at least one connecting rib, the gas channels are formed between two adjacent ring-shaped gratings, and the connecting rib is used to connect adjacent ring-shaped gratings.

[0017] the plurality of concentrically arranged ring-shaped gratings includes: a first ring-shaped grating with a minimum diameter and a second ring-shaped grating with a maximum diameter.

[0018] the plasma confinement ring further includes:

[0019] a first connecting member for connecting the inner ring assembly with the first ring-shaped grating;

[0020] a second connecting member for connecting the outer ring assembly with the second ring-shaped grating.

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

[0022] The application also provides a plasma processing device, including:

[0023] a vacuum reaction chamber;

[0024] a gas shower head arranged at a top of the vacuum reaction chamber, the gas shower head serving as an upper electrode of the vacuum reaction chamber; a susceptor arranged in the vacuum reaction chamber for supporting a substrate, the susceptor being arranged opposite to the gas shower head and serving as a lower electrode of the vacuum reaction chamber;

[0025] The plasma confinement ring is arranged between the periphery of the base and the sidewall of the vacuum reaction chamber, and the lower part of the plasma confinement ring is an exhaust area.

[0026] An exhaust device is connected to the exhaust area in the vacuum reaction chamber, and is used for discharging reaction byproducts from the vacuum reaction chamber and maintaining the vacuum environment of the vacuum reaction chamber.

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

[0028] The plasma processing device further comprises:

[0029] A middle ground ring is arranged below the plasma confinement ring, and is used for providing electric field shielding for the plasma confinement ring.

[0030] A lower ground ring is arranged below the middle ground ring, and the lower ground ring is electrically connected with the middle ground ring to form an RF ground 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 for fixedly connecting the outer ring assembly to the sidewall of the vacuum reaction chamber.

[0032] Compared with the prior art, the technical scheme has at least the following beneficial effects:

[0033] The plasma confinement ring comprises an inner ring assembly, an outer ring assembly and an exhaust passage assembly arranged therebetween, and the top surface of the exhaust passage assembly is arranged to be lower than the top surface of the inner ring assembly, so that the distance between the upper electrode in the plasma processing device and the plurality of gas passages in the plasma confinement ring is increased, the space between the upper electrode and the gas passages is expanded, the RF field strength between the upper electrode and the plasma confinement ring is reduced, the plasma density above the plasma confinement ring is reduced, the risk of plasma leakage is reduced, the risk of arc discharge under high power is reduced, the corrosion of the plasma to the protective coating coated on the surface of the plasma confinement ring is reduced, and the reliability of the device is improved. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0036] Figure 3 In another embodiment of the invention, the plasma confinement ring is... Figure 1 A schematic diagram of the structure of part A in the diagram. Detailed Implementation

[0037] The following is based on Figures 1 to 3 The preferred embodiments of the present invention will be described in detail below.

[0038] like Figure 1As shown, the present application provides a plasma processing apparatus, which has a vacuum reaction chamber 1, and an opening 101 is arranged on the side wall of the reaction chamber for accommodating the substrate to enter and exit. A gas shower head 2 is arranged on the top of the vacuum reaction chamber 1, which serves as the upper electrode of the vacuum reaction chamber 1, and the gas shower head 2 is connected with an external gas supply device 3 for delivering the reaction gas into the vacuum reaction chamber 1. A susceptor 4 is arranged in the vacuum reaction chamber 1, which is used for supporting the substrate 5 to be processed, and the susceptor 4 is arranged opposite to the gas shower head 2, and the susceptor 4 serves as the lower electrode of the vacuum reaction chamber 1. One or more radio frequency power sources 6 can be applied on the lower electrode 4 individually or on the upper electrode 2 and the lower electrode 4 respectively at the same time, so as to deliver the radio frequency power to the lower electrode 4 or the upper electrode 2 and the lower electrode 4, to generate the radio frequency electric field between the upper electrode and the lower electrode, so as to dissociate the reaction gas into plasma, which contains a large number of active particles such as electrons, ions, excited atoms, molecules and radicals, and the active particles can have a variety of physical and chemical reactions with the surface of the substrate to be processed, so that the topography of the substrate surface is changed, i.e. the processing process is completed. A plasma confinement ring 7 is arranged around the periphery of the susceptor 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 a plurality of exhaust passages are arranged on the upper surface of the plasma confinement ring 7, so as to exhaust the reaction gas through the exhaust passages, and at the same time, the plasma confinement ring 7 extinguishes the charged particles in the plasma, so as to become neutral gas flowing downward, which prevents the inner wall of the reaction chamber and the exhaust pipeline below the plasma confinement ring 7 from being polluted. A moving ring 8 is arranged around the periphery of the gas shower head 2, and when the substrate is processed, the moving ring 8 is lowered to shield the opening 101, and the plasma confinement ring 7 and the moving ring 8 jointly play a role of confining the plasma, so as to confine the plasma in the reaction area between the upper electrode and the lower electrode, and avoid the plasma from leaking to the non-reaction area to cause the damage of the components in the non-reaction area. An exhaust device 9 is arranged below the vacuum reaction chamber 1, which is connected with the exhaust area in the vacuum reaction chamber 1, and is used for exhausting the reaction by-products from the vacuum reaction chamber 1, so as to maintain the vacuum environment of the vacuum reaction chamber 1. A middle grounding ring 10 is arranged below the plasma confinement ring 7, which is used for providing the 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 with the middle grounding ring 10, so as to form a radio frequency grounding loop in the vacuum reaction chamber 1.

[0039] The plasma processing equipment in this embodiment is used for etching processes with ultra-high aspect ratios (aspect ratio greater than 40:1). This requires increasing the RF power of the RF power supply, ensuring the total power of the RF power supply 6 is greater than or equal to 10 kW. This increase in RF power leads to a corresponding increase in the RF electric field strength between the upper and lower electrodes. This increased RF field strength promotes the dissociation of the reactive gas into plasma, resulting in an increase in plasma density in the space above the substrate 5 and the plasma confinement ring 7. During the process of the plasma being discharged into the exhaust space through the plasma confinement ring 7, the ring may not be able to extinguish all charged particles in the plasma in time, potentially causing plasma leakage to the lower exhaust device 9. This situation not only damages the exhaust device 9 but also destabilizes the plasma within the reaction chamber, affecting the process results and increasing the possibility of damage to the substrate and equipment. Furthermore, the plasma confinement ring 7 is typically made of metal. To prevent corrosion from the plasma, a protective coating is usually applied to the surface of the plasma confinement ring 7. This protective coating can typically be made of anodic oxide, yttrium oxide, or other corrosion-resistant materials. Under the high field strength caused by high radio frequency power, the plasma density is higher and the ion energy is also higher, which enhances the sputtering and corrosion of the components inside the reaction chamber. For the plasma confinement ring 7, the protective coating on its surface is more easily peeled off, thereby increasing the risk of arc discharge and plasma leakage.

[0040] To solve the above problems, such as Figure 1 and Figure 2As shown, the plasma confinement ring 7 provided by the present invention includes an inner ring assembly 701 and an outer ring assembly 702, and an exhaust channel assembly 703 connecting the inner ring assembly 701 and the outer ring assembly 702 respectively. The inner ring assembly 701 contacts the periphery of the base 4, and the top of the inner ring assembly 701 is flush with the top of the base 4. The outer ring assembly 702 surrounds the inner ring assembly 701 and contacts the side wall of the vacuum reaction chamber 1. The outer ring assembly 702 is fixedly connected to the side wall of the vacuum reaction chamber 1 by a plurality of connectors 707. In addition, the top of the outer ring assembly 702 is substantially in contact with the bottom of the moving ring 8, so that the plasma is confined above the base 4 and the plasma is prevented from contacting the side wall of the vacuum reaction chamber 1. The exhaust channel assembly 703 has multiple gas channels 704 for discharging 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 lower than the top surface of the inner ring assembly 701. By setting the exhaust channel assembly 703 as a recessed structure, the distance between the upper electrode (gas spray head 2) and the multiple 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. Consequently, the plasma density above the plasma confinement ring 7 is reduced, ultimately reducing the risk of plasma leakage, reducing the risk of arc discharge under high power, and also reducing the corrosion of the protective coating on the surface of the plasma confinement ring 7 by the plasma, thus improving the reliability of the equipment.

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

[0042] By maximizing the distance between the top surface of the exhaust channel assembly 703 and the top surface of the inner ring assembly 701, that is, by further increasing the downward displacement of the exhaust channel assembly 703, better effects can be achieved in preventing plasma leakage, arc discharge, and plasma corrosion. Figure 3As shown, in another embodiment of the invention, when ensuring sufficient distance between the plasma confinement ring 7 and the intermediate grounding ring 10, and 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 contact the intermediate grounding ring 10 below to prevent interference with the electric field shielding in the vacuum reaction chamber, 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 sufficient level. The maximum value within the reasonable range, that is, the distance between the upper electrode (gas spray 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 is also expanded to the maximum value. This minimizes the radio frequency field strength between the upper electrode and the plasma confinement ring 7, minimizes the plasma density above the plasma confinement ring 7, reduces the risk of plasma leakage, reduces the risk of arc discharge under high power, and also reduces the corrosion of the protective coating 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 removal of reaction byproducts in deep holes, high aspect ratio etching processes often need to be carried out at a lower cavity gas pressure (e.g., less than 20 mTorr). This requires the exhaust device 9 to have a sufficiently large pumping capacity. The plasma confinement ring 7 is a key component that restricts the flow conduction within the reaction cavity. In order to cooperate with the exhaust device 9 to quickly extract the remaining gas in the reaction cavity, the common practice is to widen the gas channel 704 on the plasma confinement ring 7 to facilitate the rapid flow of gas. However, widening the gas channel 704 will increase the risk of plasma leakage. Therefore, a balance needs to be struck between the two based on the actual situation, and the size of the gas channel 704 on the plasma confinement ring 7 needs to be set reasonably. 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. Meanwhile, the aspect ratio of the gas channel 704 is set according to the actual situation, 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 conduction in the reaction chamber is effectively increased, making it easier to extract the reaction products and reducing polymer accumulation.

[0044] It should be noted that, in the embodiments of the present invention, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing the embodiments. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

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

Claims

1. A plasma confinement ring for surrounding a base, characterized in that, Include: An inner ring assembly having a top surface and a bottom surface surrounding the periphery of the base; An outer ring assembly that surrounds the inner ring assembly; An exhaust channel assembly is connected to the inner ring assembly and the outer ring assembly via a connector. The top surface of the exhaust channel assembly is lower than the top surfaces of the inner ring assembly and the outer ring assembly, and the bottom surface of the exhaust channel is lower than the bottom surfaces of the inner ring assembly and the outer ring assembly. The exhaust channel assembly has multiple gas channels for discharging gas to an exhaust region below the plasma confinement ring.

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

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

4. The plasma confinement ring as described in claim 3, characterized in that, The aspect ratio of the gas channel is greater than or equal to 4:

1.

5. The plasma confinement ring as described in claim 1, characterized in that, The surface of the plasma confinement ring has a protective coating.

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

7. The plasma confinement ring as described in claim 1, characterized in that, 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 as described in claim 7, characterized in that, The plurality of concentrically arranged annular grid plates include: a first annular grid plate with the smallest diameter and a second annular grid plate with the largest diameter; The plasma confinement ring also includes: A first connector is used to connect the inner ring assembly to the first annular grid plate; The second connector is used to connect the outer ring assembly to the second annular grid plate.

9. The plasma confinement ring as described in claim 1, characterized in that, The plasma confinement ring is made of at least metallic materials.

10. A plasma treatment device, characterized in that, Include: Vacuum reaction chamber; A gas spray head is disposed at the top of the vacuum reaction chamber, serving as the upper electrode of the vacuum reaction chamber; a base located inside the vacuum reaction chamber is used to support the substrate, and the base is disposed opposite to the gas spray head, serving as the lower electrode of the vacuum reaction chamber. The plasma confinement ring as described in any one of claims 1-9, wherein the plasma confinement ring is disposed around the periphery of the base and between the sidewall of the vacuum reaction chamber, and an exhaust region is located below the plasma confinement ring, the plasma confinement ring comprising: an inner ring assembly, an outer ring assembly, and an exhaust channel assembly, wherein the inner ring assembly contacts the periphery of the base, the top of the inner ring assembly is flush with the top of the base, the outer ring assembly contacts the sidewall of the vacuum reaction chamber, and the top surface of the exhaust channel assembly is lower than the top surface of the inner ring assembly; An exhaust device, connected to the exhaust area in the vacuum reaction chamber, is used to discharge reaction byproducts from the vacuum reaction chamber and maintain the vacuum environment of the vacuum reaction chamber.

11. The plasma treatment apparatus as described in claim 10, characterized in that, An radio frequency power supply is applied to the upper electrode or the lower electrode, and the total power of the radio frequency power supply is greater than or equal to 10KW.

12. The plasma treatment apparatus as described in claim 10, characterized in that, The plasma processing equipment further includes: The grounding ring disposed below the plasma confinement ring is used to provide electric field shielding for the plasma confinement ring; A lower grounding ring is disposed 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 within the vacuum reaction chamber.

13. The plasma treatment apparatus as described in claim 10, characterized in that, The plasma confinement ring includes a plurality of third connectors that fix the outer ring assembly to the sidewall of the vacuum reaction chamber.

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