TWI901062B - Plasma processing device and substrate processing method - Google Patents

Abstract

The present invention discloses a plasma processing device and a substrate processing method, relating to the field of semiconductor processing technology. The plasma processing device includes: a reaction chamber, wherein a gas shower head and a base disposed opposite the gas shower head are disposed within the reaction chamber. The gas shower head is used to transport a reaction gas into the reaction chamber, where the reaction gas is excited into plasma; a plasma confinement ring disposed around the base to prevent the plasma from entering an exhaust channel; an exhaust device for exhausting gas from the reaction chamber, wherein the exhaust path of the exhaust device passes through the plasma confinement ring; and an auxiliary gas channel for introducing electrically neutral gas into the region where the plasma confinement ring is located. The present invention can achieve low pressure conditions in the reaction chamber and increase the plasma confinement capability of the plasma confinement ring.

Description

Plasma processing device and substrate processing method

The present invention relates to the field of semiconductor processing technology, and in particular to a plasma processing device and a substrate processing method.

Plasma confinement is a key technology in plasma etching equipment. As shown in Figure 1, a conventional plasma processing device includes a vacuum reaction chamber 10, within which is located a gas shower head 22 and a susceptor 20 positioned opposite the gas shower head 22. The gas shower head 22 is positioned above the vacuum reaction chamber 10 via a grounded base 21. The gas shower head 22 is used to deliver reaction gas into the vacuum reaction chamber 10 and simultaneously serves as the upper electrode of the vacuum reaction chamber. The susceptor 20 also serves as the lower electrode of the vacuum reaction chamber, forming a reaction zone between the upper and lower electrodes. A radio frequency electric field is generated between the upper electrode and the lower electrode to dissociate the reaction gas into plasma 30. The plasma 30 contains active particles such as electrons, ions, excited atoms, molecules, and free radicals.

A plasma confinement ring 40 is disposed around the susceptor 20 to confine the plasma within the reaction region. The plasma flowing through the plasma confinement ring 40 is extinguished by the limiting structure of the plasma confinement ring 40 itself, such as a through-hole or slit design, and is then guided and discharged as a neutral gas flow. With the continuous development of logic and storage components, low-pressure conditions (less than or equal to 20mtorr) are increasingly used in their etching processes. This places higher demands on plasma confinement: Lower pressure environments need to be achieved by reducing the air resistance of the plasma confinement ring 40. This means further reducing the confinement structure, such as increasing the aperture, increasing the slot width, and reducing the vertical depth. These measures inevitably reduce the effect of plasma confinement. In other words, for low-air-resistance configurations, due to the reduction of the confinement structure, the overlapping area of the plasma sheath on the corresponding plasma confinement ring 40 also tends to weaken or even disappear, ultimately causing plasma to penetrate the confinement ring and leak into the lower part of the cavity. Plasma leakage can corrode the inner wall of the bell pendulum valve, molecular pump and pipeline, reducing the life of the components.

The present invention aims to provide a plasma processing apparatus and a substrate processing method to solve the problem that the plasma confinement effect of a plasma confinement ring with a low air resistance configuration is weakened under low pressure conditions.

To address the above issues, the present invention is implemented through the following technical solutions: a plasma processing device, comprising: a reaction chamber, wherein a gas shower head and a base arranged opposite to the gas shower head are disposed in the reaction chamber, the gas shower head being used to transport reaction gas into the reaction chamber, wherein the reaction gas is excited into plasma in the reaction chamber; a plasma confinement ring, which is disposed around the base to prevent the plasma from entering an exhaust channel; an exhaust device, which exhausts the reaction chamber, and the exhaust path of the exhaust device passes through the plasma confinement ring; and an auxiliary gas channel, which is used to introduce electrically neutral gas into the area where the plasma confinement ring is located.

Optionally, the plasma confinement ring includes: an inner confinement ring, an outer confinement ring, and a plurality of annular grids, wherein the plurality of annular grids are located between the inner confinement ring and the outer confinement ring; there is a spacing between two adjacent annular grids, and at least two of the spacings are different.

Optionally, the plurality of spacings are distributed along the radial direction of the plasma confinement ring in a trend of being dense inside and sparse outside.

Optionally, the spacing is 1-3 mm.

Optionally, the plasma confinement ring includes: an inner confinement ring, an outer confinement ring, and a plurality of annular grids, wherein the plurality of annular grids are located between the inner confinement ring and the outer confinement ring; the auxiliary gas channel is configured by the inner confinement ring or the outer confinement ring, and allows the electrically neutral gas to pass to the top of the plasma confinement ring.

Optionally, the system further comprises a grounding ring, the grounding ring being arranged below the plasma confinement ring, the grounding ring being provided with a gas supply channel, the gas supply channel being used to connect the auxiliary gas channel with an electrically neutral gas source.

Optionally, the gas outlet of the auxiliary gas channel is located at the upper portion of the outer wall of the inner ring of the constraint ring or the upper portion of the inner wall of the outer ring of the constraint ring.

Optionally, the air outlet is an annular groove or a plurality of air outlet holes arranged at intervals along the circumference of the inner ring of the constraint ring.

Optionally, the annular groove has a width of 1-3 mm.

Optionally, the gas outlet introduces electrically neutral gas into the area where the plasma confinement ring is located at an angle to the horizontal plane.

Optionally, the angle is 0-30°.

Optionally, the grounding ring is provided with a gas outlet for introducing the electrically neutral gas into the lower surface of the plasma confinement ring.

Optionally, it includes: a grounding ring, the grounding ring is arranged below the plasma confinement ring, and the auxiliary gas channel is configured by the grounding ring.

Optionally, the grounding ring includes an inner grounding ring, an outer grounding ring and a plurality of spokes, wherein the plurality of spokes are used to connect the inner grounding ring and the outer grounding ring; the air outlet of the auxiliary gas channel is arranged on the inner grounding ring and/or the outer grounding ring.

Optionally, the auxiliary gas channel is configured by the cavity wall of the reaction chamber.

Optionally, the gas outlet of the auxiliary gas channel is located above or below the plasma confinement ring.

Optionally, the electrically neutral gas is any one of helium, neon, nitrogen and hydrogen.

On the other hand, the present invention also provides a substrate processing method using the plasma processing device as described above, including: placing a substrate on the base; introducing a reaction gas into the reaction chamber and ionizing it into plasma to etch the substrate, an exhaust device exhausting the reaction chamber, and introducing an electrically neutral gas into the area where the plasma confinement ring is located through the auxiliary gas channel.

The present invention has at least one of the following technical effects: The present invention introduces electrically neutral gas into the area where the plasma confinement ring is located through the provided auxiliary gas channel, causing collision between the plasma and the electrically neutral gas, thereby increasing the probability of plasma quenching and reducing plasma leakage without affecting the gas resistance of the plasma confinement ring.

Because the plasma density distribution above the plasma confinement ring varies, the present invention can design the spacing of the annular grids in the plasma confinement ring based on the plasma density distribution, so that all spacings are the same, partially the same, or completely different. This reduces the air resistance of the plasma confinement ring and helps achieve low-pressure reaction conditions inside the reaction chamber.

In addition, generally, the plasma dense area is closer to the inner ring of the confinement ring. Therefore, plasma penetration is more likely to occur at the annular grid near the inner ring of the confinement ring. Therefore, the present invention distributes the spacing of the multiple annular grids along the radial direction of the plasma confinement ring in a trend of dense inner and sparse outer. That is, the annular grid near the inner ring of the confinement ring is denser and sparser. The grid spacing is smaller than that of the annular grids near the outer ring of the confinement ring. This reduces the need for restrictive structures (increasing the annular grid spacing) while minimizing the impact on the plasma confinement ring's confinement capability. This allows for easier extraction of post-reaction waste gases outside the reaction chamber, allowing the internal pressure of the reaction chamber to more easily meet low pressure requirements. Furthermore, to prevent plasma leakage, the present invention incorporates an auxiliary gas channel. Neutral gas is introduced into the area surrounding the plasma confinement ring to quench the plasma.

The auxiliary gas channel provided by the present invention is configured by the inner ring or the outer ring of the confinement ring, and allows the electrically neutral gas to flow above the plasma confinement ring. Furthermore, a gas supply channel is configured in the grounding ring, and the gas supply channel is used to connect the auxiliary gas channel to the electrically neutral gas source, thereby avoiding major modifications to the device and reducing device improvement costs.

The following describes in further detail the plasma processing apparatus and substrate processing method proposed by the present invention, using drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the embodiments of the present invention. Please refer to the drawings to further clarify the objectives, features, and advantages of the present invention. It should be noted that the structures, proportions, sizes, etc. depicted in the figures accompanying this specification are intended solely to facilitate understanding and reading by those skilled in the art in conjunction with the contents disclosed herein. They are not intended to limit the implementation of the present invention and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in size, provided they do not affect the efficacy and objectives of the present invention, shall remain within the scope of the technical content disclosed herein.

The present invention provides a plasma processing device that prevents plasma leakage by providing an auxiliary gas channel to introduce electrically neutral gas into the area where the plasma confinement ring is located. This solves the problem in conventional technology of reduced plasma confinement effect caused by using a low-resistance plasma confinement ring to reduce the gas pressure in the reaction chamber.

As shown in FIG2 , this embodiment provides a plasma processing device, comprising: a reaction chamber 100, a gas shower head 220 and a base 200 disposed opposite to the gas shower head 220, wherein the gas shower head 220 is used to transport a reaction gas into the reaction chamber 100, and the reaction gas is excited into plasma 300 in the reaction chamber 100. a plasma confinement ring 400 disposed around the base 200 to prevent the plasma 300 from entering the exhaust channel; an exhaust device (not shown in FIG. 1 ) for exhausting the reaction chamber 100, wherein the exhaust path 310 of the exhaust device passes through the plasma confinement ring 400; and an auxiliary gas channel 420 for introducing electrically neutral gas 600 into the area where the plasma confinement ring 400 is located.

This embodiment provides an auxiliary gas channel to introduce electrically neutral gas into the area where the plasma confinement ring is located, causing collisions between the plasma and the electrically neutral gas, thereby increasing the probability of plasma quenching and reducing plasma leakage without affecting the gas resistance of the plasma confinement ring.

As shown in FIG3 , the plasma confinement ring 400 provided in this embodiment includes an inner confinement ring 410, an outer confinement ring 411, and a plurality of annular grids 412. The plurality of annular grids 412 are located between the inner confinement ring 410 and the outer confinement ring 411. There is a spacing between two adjacent annular grids 412, and at least two of the spacings are different.

In this embodiment or other embodiments, the spacing between the annular grids 412 in the plasma confinement ring 400 can be designed based on the plasma density distribution, so that all spacings are the same, partially the same, or completely different. This can reduce the air resistance of the plasma confinement ring 400 and help the interior of the reaction chamber 100 achieve low-pressure reaction conditions.

Generally, the closer to the center of the reaction chamber 100, the greater the plasma density. This is because the inner confinement ring 410 of the plasma confinement ring 400 is closer to the center of the reaction chamber 100 than the outer confinement ring 411. Therefore, the plasma density near the inner confinement ring 410 is greater than that near the outer confinement ring 411. Therefore, plasma leakage is more likely to occur near the annular grid 412 near the inner confinement ring 410. Therefore, in this embodiment, the spacing between the multiple annular grids 412 is arranged to form a denser inner and sparser outer distribution along the radial direction of the plasma confinement ring 400.

This embodiment distributes the plurality of annular grids radially along the plasma confinement ring in a denser inner-to-sparser outer-dispersion pattern. Specifically, the spacing of the annular grids near the innermost ring of the confinement ring is smaller than the spacing of the annular grids near the outermost ring. This reduces the number of restrictive structures (increasing the spacing of the annular grids) while minimizing the impact on the confinement capability of the plasma confinement ring. This allows for easier extraction of post-reaction waste gas from the reaction chamber, allowing the pressure inside the reaction chamber to more easily meet low pressure requirements.

Furthermore, to prevent plasma leakage, the present embodiment introduces a neutral gas into the region where the plasma confinement ring 400 is located through an auxiliary gas channel to extinguish the plasma. The combined effects of the two aforementioned technical measures (the overlapping sheaths between the surfaces of the annular grids extinguish the plasma flowing therethrough, and the collision between the plasma and the introduced neutral gas promotes plasma extinguishment) further ensure that the plasma is extinguished before being pumped out of the reaction chamber by the pumping device.

In this embodiment, the axial height of the annular grid 412 ranges from 10 to 30 mm, and the spacing of the annular grid 412 ranges from 1 to 3 mm. For example, the spacing of the portion of the annular grid 412 disposed near the inner ring of the constraint ring may be 1 to 2 mm, and the spacing of the portion of the annular grid 412 disposed near the outer ring of the constraint ring may be 2 to 3 mm. However, the present invention is not limited thereto. It will be understood that the above-mentioned spacing values of the annular grid 412 are merely preferred examples, and the spacing of the annular grid 412 may be arbitrarily selected within the range of 1 to 3 mm according to actual circumstances. Typically, the annular grids 412 provided in conventional art are evenly spaced, with a spacing of 1.5 mm. However, even with such a small spacing, there is still a risk of plasma penetrating the annular grids 412 and flowing into the exhaust channel along the exhaust path. To maintain a low pressure within the reaction chamber 100, conventional art cannot simply prevent plasma leakage by increasing the grid spacing. This embodiment uses an auxiliary gas channel to introduce an electrically neutral gas to assist in extinguishing the plasma, thereby preventing plasma from entering the exhaust channel.

Continuing with FIG. 3 , in this embodiment, the auxiliary gas channel 420 is configured within the inner confinement ring 410 of the plasma confinement ring 400 and allows the electrically neutral gas 600 to flow above the plasma confinement ring 400. In this embodiment, the outlet of the auxiliary gas channel 420 is located at the upper portion of the outer wall of the inner confinement ring 410. The electrically neutral gas within the auxiliary gas channel 420 flows from the inner confinement ring 410 toward the outer confinement ring 411. Since the plasma-dense area is closer to the inner ring 410 of the confinement ring, when the electrically neutral gas in the auxiliary gas channel 420 flows out from the inner ring 410 of the confinement ring toward the outer ring 411 of the confinement ring, the electrically neutral gas concentration in the area close to the inner ring 410 of the confinement ring is higher than the electrically neutral gas concentration in the area far from the inner ring 410 of the confinement ring, thereby ensuring the probability of extinguishing the plasma in the plasma-dense area and reducing plasma leakage.

It is understood that in some other embodiments, the auxiliary gas channel is configured by the outer ring of the confinement ring and allows the electrically neutral gas to flow above the plasma confinement ring. The outlet of the auxiliary gas channel is located at the upper portion of the inner wall of the outer ring of the confinement ring. The electrically neutral gas in the auxiliary gas channel flows from the outer ring 411 of the confinement ring toward the inner ring 410 of the confinement ring. This can also increase the probability of quenching the plasma that flows into the plasma confinement ring area and prevent plasma leakage from the plasma confinement ring.

Continuing with FIG3 , in this embodiment, the air outlet is an annular groove or a plurality of air outlet holes spaced circumferentially along the constraint ring inner ring 410. Preferably, the width d of the annular groove is 1-3 mm.

This outlet allows for uniform flow of neutral gas around the circumference of plasma confinement ring 400, ensuring that the externally introduced neutral gas completely covers the area surrounding the plasma confinement ring. During etching, the plasma flow mixes with the neutral gas flow in this area, colliding and extinguishing itself. This further enhances the plasma confinement ring's ability to confine the plasma and extends the life of the device, particularly the pumping channel and pumping mechanism.

In this embodiment, the gas outlet introduces electrically neutral gas into the area where the plasma confinement ring 400 is located at an angle relative to the horizontal plane. Preferably, the angle ranges from 0° to 30°. When the angle at which the electrically neutral gas flows out of the gas outlet is not zero, it can preemptively extinguish plasma above the plasma confinement ring 400, increase the gas flow coverage and uniformity of the area where the plasma confinement ring is located, and further enhance the plasma confinement capability of the plasma confinement ring. When the angle of the electrically neutral gas flowing out of the gas outlet is 0 degrees, that is, the electrically neutral gas flows outward/inward in a horizontal direction along the radial direction of the plasma confinement ring, the impact on the distribution of the plasma in the reaction chamber can be reduced.

Continuing with reference to FIG. 2 and FIG. 3 , this embodiment further includes a grounding ring (comprising a lower grounding ring 500 and a middle grounding ring 510 ). The grounding ring is disposed below the plasma confinement ring 400 . A gas supply channel is disposed within the grounding ring. The gas supply channel is used to connect the auxiliary gas channel 420 to an electrically neutral gas source (not shown in FIG. 2 and FIG. 3 ).

A sealing ring 700 is provided at the interface where the gas supply channel and the auxiliary gas channel 420 communicate with each other, thereby achieving an airtight connection between the two.

This embodiment arranges a gas supply channel in an existing component to pass the electrically neutral gas 600 into the area where the plasma confinement ring 400 is located, thereby extinguishing the plasma. The gas supply channel is easy to set up, avoiding major changes to the processing device and reducing the cost of device improvement.

In some other embodiments, as shown in FIG4 , the auxiliary gas channel 431 of the plasma processing apparatus can be configured as a grounding ring. The grounding ring is provided with a gas outlet 432 for introducing the electrically neutral gas 600 to the lower surface of the plasma confinement ring 400. If plasma is not extinguished by the plasma confinement ring 400 and leaks onto the lower surface of the plasma confinement ring 400, the plasma may collide with the electrically neutral gas 600 and be extinguished, thereby reducing the risk of leakage.

Specifically, in this embodiment, the grounding ring includes an inner grounding ring (lower grounding ring) 500, an outer grounding ring (middle grounding ring) 510, and multiple radials 511. The multiple radials 511 are used to connect the inner grounding ring 500 and the outer grounding ring 510. The outlet 432 of the auxiliary gas channel 431 is set at the inner grounding ring 500 and/or the outer grounding ring 510.

In addition, an anti-corrosion coating is provided on the middle ground ring 510. Increasing the thickness of the anti-corrosion coating increases the capacitance of the plasma confinement ring to ground. Increasing the capacitance of the plasma confinement ring 400 to ground is beneficial to increasing the thickness of the sheath, thereby further enhancing the plasma confinement capability of the plasma confinement ring 400.

In some other embodiments, the auxiliary gas channel is formed by the chamber wall; the outlet of the auxiliary gas channel is located above the plasma confinement ring. This allows the introduction of electrically neutral gas into the area where the plasma confinement ring is located, achieving the low-pressure process parameter requirements within the chamber without affecting the plasma confinement ring's ability to confine the plasma.

In this embodiment, the electrically neutral gas is any one of helium, neon, nitrogen, and hydrogen, but the present invention is not limited thereto. It should be understood that any electrically neutral gas that exhibits a high breakdown voltage on the Paschen curve and is less likely to form a plasma state under low pressure (e.g., pressure less than or equal to 20 mtorr) is suitable. Preferably, the electrically neutral gas provided in this embodiment is helium. As an inert gas that is relatively difficult to dissociate under low pressure conditions, helium is currently widely used in etching equipment and presents a relatively low risk of introduction, enabling both plasma quenching and chamber contamination.

In this embodiment, the plasma flow doped with helium is obstructed by the annular grid, the sheath, and the helium atoms, making it easier to extinguish, thereby improving the plasma confinement capability of the plasma confinement ring.

Continuing with Figure 2, the gas showerhead 220 can be positioned above the reaction chamber 100 via a grounded base 210. The gas showerhead 220 is used to deliver reaction gas to the reaction chamber 100 and simultaneously serves as the upper electrode of the reaction chamber 100. The base 210 also serves as the lower electrode of the vacuum reaction chamber, forming a reaction region between the upper and lower electrodes. An RF electric field is generated between the upper and lower electrodes, dissociating the reaction gas into plasma 300. Plasma 300 contains a large number of active species, including electrons, ions, excited atoms, molecules, and free radicals.

On the other hand, this embodiment also provides a substrate processing method, which is performed using the plasma processing apparatus described in the above embodiment, including: placing a substrate on the susceptor 200; introducing a reactive gas into the reaction chamber 100 and ionizing it into plasma 300 to etch the substrate; evacuating the reaction chamber 100 with an exhaust device; and introducing an electrically neutral gas into the area where the plasma confinement ring 400 is located through the auxiliary gas channel 420. It will be understood that there is no specific order for performing these steps in this substrate processing method. This embodiment can achieve low-pressure process parameter requirements within the reaction chamber without changing the gas resistance of the plasma confinement ring.

In summary, the present invention provides an auxiliary gas channel to introduce electrically neutral gas into the area where the plasma confinement ring is located, causing collisions between the plasma and the neutral gas, thereby increasing the probability of plasma quenching. This reduces plasma leakage without affecting the air resistance of the plasma confinement ring, thereby achieving the goal of improving the plasma confinement capability of the plasma confinement ring.

It should be noted that, in this document, the terms "comprise," "include," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, elements defined by the phrase "comprise a..." do not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the elements.

In the description of the present invention, it should be understood that terms such as "center," "height," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate positions or locations based on the positions or locations shown in the drawings. These terms are used solely to facilitate and simplify the description of the present invention and do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations of the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of this invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," and "fixed" should be interpreted broadly. For example, they may refer to fixed or removable connections, or integration; mechanical or electrical connections; direct connections or indirect connections through an intermediate medium; and connections between two components, or interactions between two components. Those skilled in the art will understand the specific meanings of these terms in the context of this invention.

In the present invention, unless otherwise expressly specified or limited, "above" or "below" a first feature of a second feature may include the first and second features being in direct contact, or the first and second features not being in direct contact but being in contact via another feature between them. Furthermore, "above," "above," and "above" a first feature of a second feature may include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher level than the second feature. "Below," "below," and "below" a first feature of a second feature may include the first feature being directly below or diagonally below the second feature, or simply indicate that the first feature is at a lower level than the second feature.

Although the present invention has been described in detail through the preferred embodiments described above, it should be understood that the above description should not be considered as limiting the present invention. After reading the above description, various modifications and alternatives to the present invention will be apparent to those skilled in the art. Therefore, the scope of protection of the present invention is defined by the attached patent application.

10: Vacuum chamber 20: Base 21: Grounding plate 22: Gas shower head 30: Plasma 40: Plasma confinement ring 100: Reaction chamber 200: Base 210: Grounding plate 220: Gas shower head 300: Plasma 400: Plasma confinement ring 410: Inner confinement ring 411: Outer confinement ring 412: Annular grille 420: Auxiliary gas channel 431: Auxiliary gas channel 432: Gas outlet 500: Inner grounding ring (lower grounding ring) 510: Outer ground ring (center ground ring) 511: Radial 600: Electrically neutral gas 700: Sealing ring d: Slot width

Figure 1 is a schematic diagram of the structure of a plasma processing device in the prior art; Figure 2 is a schematic diagram of the structure of a plasma processing device provided in an embodiment of the present invention; Figure 3 is an enlarged schematic diagram of a portion of the structure of a plasma confinement ring provided in an embodiment of the present invention; Figure 4 is an enlarged schematic diagram of a portion of the structure of a plasma confinement ring provided in another embodiment of the present invention.

410 Inner restraint ring 411 Outer restraint ring 412 Annular grille 420 Auxiliary gas channel 500 Inner grounding ring (lower grounding ring) 510 Outer grounding ring (middle grounding ring) 600 Neutral gas 700 Sealing ring d Slot width

Claims (18)

A plasma processing device comprises: a reaction chamber, wherein a gas shower head is disposed within the reaction chamber, and a base disposed opposite the gas shower head; the gas shower head is used to transport reaction gas into the reaction chamber, where the reaction gas is excited into plasma; a plasma confinement ring disposed around the base to prevent the plasma from entering an exhaust channel; and an exhaust device for exhausting gas from the reaction chamber, wherein the exhaust path of the exhaust device passes through the plasma confinement ring. The device is characterized in that it further comprises: an auxiliary gas channel for introducing electrically neutral gas into the area where the plasma confinement ring is located. The plasma processing device as described in claim 1, wherein the plasma confinement ring includes: an inner confinement ring, an outer confinement ring, and a plurality of annular grids, wherein the plurality of annular grids are located between the inner confinement ring and the outer confinement ring; there is a spacing between two adjacent annular grids, and at least two of the spacings are different. The plasma processing apparatus of claim 2, wherein the plurality of spacings are distributed along the radial direction of the plasma confinement ring in a trend of being dense inside and sparse outside. The plasma processing device as described in claim 2, wherein the spacing is 1~3mm. The plasma processing device as described in claim 1, wherein the plasma confinement ring includes: an inner confinement ring, an outer confinement ring, and a plurality of annular grids, and the plurality of annular grids are located between the inner confinement ring and the outer confinement ring; the auxiliary gas channel is configured by the inner confinement ring or the outer confinement ring, and allows the electrically neutral gas to pass to the top of the plasma confinement ring. The plasma processing device as described in claim 5 further includes: a grounding ring, the grounding ring is arranged below the plasma confinement ring, and a gas supply channel is configured in the grounding ring, and the gas supply channel is used to connect the auxiliary gas channel with an electrically neutral gas source. The plasma processing device as described in claim 5, wherein the gas outlet of the auxiliary gas channel is located at the upper part of the outer wall of the inner ring of the constraint ring or the upper part of the inner wall of the outer ring of the constraint ring. The plasma processing device as described in claim 7, wherein the air outlet is an annular groove or a plurality of air outlet holes arranged at intervals along the circumference of the inner ring of the constraint ring. The plasma processing device as described in claim 8, wherein the width of the annular groove is 1~3 mm. The plasma processing device as described in claim 7, wherein the gas outlet introduces electrically neutral gas into the area where the plasma confinement ring is located at an angle to the horizontal plane. A plasma processing device as described in claim 10, wherein the angle is 0~30°. The plasma processing device as described in claim 6, wherein the grounding ring is provided with a gas outlet for introducing the electrically neutral gas into the lower surface of the plasma confinement ring. The plasma processing device as described in claim 1, further comprising: a grounding ring, wherein the grounding ring is arranged below the plasma confinement ring, and the auxiliary gas channel is configured by the grounding ring. A plasma processing device as described in claim 13, wherein the grounding ring includes an inner grounding ring ring, an outer grounding ring ring and a plurality of spokes, and the plurality of spokes are used to connect the inner grounding ring ring and the outer grounding ring ring; the air outlet of the auxiliary gas channel is arranged on the inner grounding ring ring and/or the outer grounding ring ring. The plasma processing apparatus as described in claim 1, wherein the auxiliary gas channel is configured by a cavity wall of the reaction chamber. The plasma processing apparatus of claim 15, wherein the gas outlet of the auxiliary gas channel is located above or below the plasma confinement ring. The plasma processing apparatus of claim 1, wherein the electrically neutral gas is any one of helium, neon, nitrogen, and hydrogen. A substrate processing method, characterized by employing the plasma processing apparatus of any one of claims 1 to 17, comprising: placing a substrate on the susceptor; introducing a reactive gas into the reaction chamber to ionize it into plasma for etching the substrate; evacuating the reaction chamber with an exhaust device; and introducing electrically neutral gas into the region where the plasma confinement ring is located through the auxiliary gas channel.