TWI894705B - Plasma processing equipment - Google Patents

Abstract

The present invention discloses a plasma processing device, comprising a reaction chamber, in which an upper electrode and a lower electrode assembly opposite the upper electrode are disposed. The lower surface of the lower electrode assembly is connected to an RF guide rod, thereby connecting to an RF power supply. An RF shielding component is disposed in the reaction chamber, surrounding the RF guide rod. A capacitance adjustment device is disposed in a space formed by the RF shielding component, the lower electrode assembly, and the bottom wall of the reaction chamber. The capacitance between the lower electrode assembly or the RF guide rod and ground is adjusted by the capacitance adjustment device. Through the above-mentioned device, a single chamber can meet the needs of multiple RF frequencies, providing feasibility for multi-frequency applications of a single chamber.

Description

Plasma processing equipment

The present invention relates to the field of semiconductor processing technology, and more particularly to a plasma processing device with an adjustable reaction cavity resonant frequency.

Plasma processing devices are widely used in the processing and manufacturing of semiconductor wafers, such as plasma deposition and etching. Figure 1 shows a schematic diagram of a typical plasma processing device structure. The plasma processing device includes a reaction chamber 100, which is made of metal and grounded to shield the radio frequency field within the chamber. The reaction chamber 100 includes a gas shower head located at the top and a base arranged opposite the gas shower head. The gas shower head is used to transport reaction gas to the reaction chamber 100 and serves as the upper electrode 141 of the reaction chamber 100. The base serves as the lower electrode 111. An electrostatic chuck 112 is also provided above the base, and the wafer to be processed is fixed by the electrostatic chuck 112. An RF guide rod 150 connects the susceptor and an RF power source outside the reaction chamber. The RF power from the RF power source passes through a matching network and the RF guide rod 150 before being applied to the lower electrode. This creates an RF electric field between the upper and lower electrodes, ionizing the reactive gas between them to generate plasma. This plasma then etches the wafer to be processed above the susceptor.

A focusing ring 121 surrounds the susceptor to adjust the electric field distribution at the wafer edge, ensuring uniform plasma control during the etching process. A cover ring 122 surrounds the outer edge of the focusing ring 121 to prevent plasma erosion of components beneath it. A plasma confinement ring 123 surrounds the cover ring 122, confining the plasma within the reaction zone above the lower electrode 111 while exhausting reactive gases. A grounding ring 132 is located below the plasma confinement ring 123, providing electromagnetic shielding for the plasma confinement ring 123 and forming an RF ground loop within the reaction chamber. An insulating ring 131 is also provided between the ground ring 132 and the base to shield the radio frequency signal applied to the lower electrode 111 within the base.

Currently, when using the aforementioned plasma processing equipment to etch at different RF frequencies, in order to ensure a stable etching rate, the resonant frequency of the reaction chamber must be strictly measured during the design of the reaction chamber to ensure that the resonant frequency of the cavity avoids the RF frequency and its multiples.

With the continuous advancement of technology, an increasing number of RF frequencies are being used in plasma etching, currently expanding to 400kHz, 2MHz, 13.56MHz, 40MHz, and 60MHz. This has led to an increasing number of frequencies that the cavity's resonant frequency must avoid. To further expand the process window, plasma processing equipment is beginning to adopt dual-frequency or even multi-frequency configurations. Therefore, the cavity's resonant frequency must not only avoid each main frequency but also take into account the multiples of each main frequency and the difference frequencies between them. Because the cavity's resonant frequency is determined by the cavity structure, multi-frequency configurations significantly increase the difficulty of cavity design.

The purpose of this invention is to provide a plasma processing device that adjusts the resonant frequency within the cavity without changing the cavity structure, thereby resolving the problem that the multi-frequency configuration of current plasma processing devices places high demands on the cavity structure design.

To achieve the above-mentioned objectives, the present invention discloses a plasma processing apparatus comprising: a reaction chamber defined by a top wall, a bottom wall, and side walls; an upper electrode and a lower electrode assembly opposing the upper electrode disposed within the reaction chamber; the lower electrode assembly connected to an RF power supply via an RF guide rod; an RF shielding member disposed below the lower electrode assembly, the RF shielding member surrounding the RF guide rod; and a capacitance adjustment device disposed within the space formed by the RF shielding member, the lower electrode assembly, and the bottom wall of the reaction chamber. The capacitance between the lower electrode assembly and ground is adjusted by the capacitance adjustment device.

Optionally, the capacitance adjustment device is a movable ground ring disposed around the RF guide rod, wherein the upper surface of the movable ground ring is substantially parallel to the lower surface of the lower electrode assembly. The capacitance between the lower electrode assembly and the ground is adjusted by adjusting the relative distance between the movable ground ring and the lower electrode assembly.

Optionally, the movable grounding ring is connected to a metal actuator rod extending from the bottom wall of the reaction chamber, and the metal actuator rod drives the movable grounding ring to move up and down within the reaction chamber.

Optionally, the metal transmission rod is connected to the bottom wall of the reaction chamber via a bellows.

Optionally, the movable grounding ring is connected to three metal transmission rods.

Optionally, the area between the movable grounding ring and the lower electrode assembly is 1000-70000 mm ² .

Optionally, the adjustable relative distance between the movable grounding ring and the lower electrode assembly is 0.1-20 mm.

Optionally, the mobile ground ring includes multiple fan rings.

Optionally, the capacitance adjustment device is a motor capacitor, one end of which is electrically connected to the lower electrode assembly and the other end is grounded.

Optionally, the motor capacitor is connected to a feed ring via a plurality of radio frequency transmission lines, and the feed ring is electrically connected to the lower electrode assembly.

The present invention also discloses another plasma processing device, comprising: a reaction chamber surrounded by a reaction chamber top wall, a reaction chamber bottom wall, and reaction chamber side walls; an upper electrode and a lower electrode assembly opposite the upper electrode disposed within the reaction chamber; the lower electrode assembly connected to an RF power supply via an RF guide rod; an RF shielding component disposed below the lower electrode assembly, the RF shielding component surrounding the RF guide rod; and a capacitance adjustment device disposed within the space formed by the RF shielding component, the lower electrode assembly, and the reaction chamber bottom wall; the capacitance between the RF guide rod and ground is adjusted by the capacitance adjustment device.

Optionally, the capacitance adjustment device is a movable grounding sleeve disposed around the RF guide rod, the movable grounding sleeve being coaxially disposed with the RF guide rod, and the capacitance between the RF guide rod and ground is adjusted by adjusting the relative area between the movable grounding sleeve and the RF guide rod.

Optionally, the movable grounding sleeve is disposed through the bottom wall of the reaction chamber, with a first end of the movable grounding sleeve disposed below the lower electrode assembly and above the bottom wall of the reaction chamber, and a second end of the movable grounding sleeve disposed below the bottom wall of the reaction chamber.

Optionally, the movable grounding sleeve is connected to the bottom wall of the reaction chamber via a bellows.

Optionally, the movable grounding sleeve is connected to a metal transmission rod, and the metal transmission rod drives the movable grounding sleeve to move up and down in the reaction chamber.

Optionally, the relative distance between the movable ground sleeve and the radio frequency guide rod is 0.1-20 mm.

Optionally, the adjustable relative area between the movable grounding sleeve and the lower electrode assembly is 1000-12000 mm ² .

Optionally, the movable grounding sleeve is connected to three metal transmission rods.

Optionally, the capacitance adjustment device is a motor capacitor, one end of which is electrically connected to the radio frequency guide rod and the other end is grounded.

Optionally, the motor capacitor is connected to a feed ring via a plurality of radio frequency transmission lines, and the feed ring is electrically connected to the radio frequency guide rod.

Compared with the prior art, the present invention has the following beneficial effects: the present device does not change the original structure of the reaction chamber, but adds a capacitance adjustment device in the reaction chamber, which cooperates with the original structure of the reaction chamber and is connected in parallel with the original inherent capacitance of the reaction chamber, thereby changing the total capacitance of the cavity and further changing the resonance frequency of the cavity; the above-mentioned capacitance adjustment device is movable or its capacitance is adjustable, and the resonance frequency of the cavity is adjusted according to the actual situation. By moving the capacitance adjustment device or changing its capacitance according to the RF frequency being used, the capacitance between the reaction cavity's lower electrode assembly or RF guide rod and ground is adjusted, thereby adjusting the cavity's resonant frequency to avoid multiple main frequencies and their multiples and difference frequencies. Through this device, a single cavity can meet the needs of multiple RF frequencies, making multi-frequency applications of a single cavity feasible.

100: Reaction Chamber

111: Lower electrode

112: Electrostatic Chuck

121: Focus Ring

122: Covering Ring

123: Plasma Confinement Ring

131: Insulation Ring

132: Ground Ring

141: Upper electrode

150:RF Guide Rod

100’: Reaction Chamber

101: Bottom wall of reaction chamber

111: Bottom electrode assembly

140: Mobile Ground Ring

141:Metal drive rod

142: First Corrugated Tube

143: Mobile Grounding Sleeve

144: Second Corrugation

Figure 1 is a schematic diagram of a plasma processing device in the prior art; Figure 2 is a schematic diagram of a plasma processing device according to one embodiment of the present invention; Figure 3 is a schematic diagram of a plasma processing device according to another embodiment of the present invention; and Figure 4 is a resonance curve of the plasma processing device of the present invention and a device in the prior art.

The following will be combined with Figures 1 to 4 of the embodiments of the present invention to provide a detailed description of the technical solutions, structural features, objectives achieved, and effects of the embodiments of the present invention.

It should be noted that the figures are extremely simplified and not to exact scale. They are intended solely to facilitate and clearly illustrate the embodiments of the present invention and are not intended to limit the conditions for its implementation. Therefore, they have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments to 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.

It should be noted that, in the present invention, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any actual relationship or order between these entities or operations. Moreover, 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 the elements explicitly listed, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

The present invention discloses a plasma processing device with adjustable cavity resonant frequency, as shown in FIG2 , comprising: a reaction chamber 100′ surrounded by a reaction chamber top wall, a reaction chamber bottom wall 101, and reaction chamber side walls; the reaction chamber 100′ includes a gas shower head at the top and a base disposed opposite the gas shower head; the gas shower head serves as an upper electrode 141 of the reaction chamber 100′, the base serves as a lower electrode assembly 111, and the upper electrode 141 and the lower electrode assembly 111 are spaced apart. The dotted area represents the plasma processing area. RF guide rods 150 transmit external RF power to the lower electrode assembly 111, thereby applying RF frequency to the lower electrode assembly 111. During the process, a reactive gas is delivered into the reaction chamber 100' via a gas showerhead. The RF frequency is applied to the lower electrode assembly 111, generating an RF electric field between the upper and lower electrodes. This ionizes the reactive gas between the upper and lower electrodes, generating plasma that etches the wafer to be processed on the susceptor.

An electrostatic chuck 112 is mounted above the susceptor, generating electrostatic attraction to support and secure the wafer during processing. Surrounding the susceptor are a focusing ring 121 and a cover ring 122. The focusing ring 121 adjusts the electric field distribution at the wafer edge, ensuring uniform plasma control during etching. The cover ring 122 prevents plasma in the reaction chamber from corroding components beneath it. Surrounding the cover ring 122 is a plasma confinement ring 123, which confines the plasma within the reaction zone between the upper and lower electrodes while exhausting the reactive gases. Below the plasma confinement ring 123 is a grounding ring 132, which acts as an RF shield, providing electromagnetic shielding for the plasma confinement ring 123 and forming an RF ground loop within the reaction chamber. An insulating ring 131 is also located between the grounding ring 132 and the base, working in conjunction with the reaction chamber walls to shield the RF signal applied to the lower electrode assembly 111 from the reaction chamber.

To adjust the cavity's resonant frequency, in this embodiment, a movable ground ring 140 is installed within the space formed by the lower electrode assembly 111, the reaction chamber bottom wall 101, and the ground ring 132, serving as a capacitance adjustment device. The movable ground ring 140 surrounds the RF guide rod 150, with its upper surface roughly parallel to the lower surface of the lower electrode assembly 111. The movable ground ring 140 is made of a conductive material and, together with the lower electrode assembly 111, forms a first parallel plate capacitor _C1 .

The lower surface of the mobile grounding ring 140 is connected to a metal actuator rod 141. One end of the metal actuator rod 141 is connected to the mobile grounding ring 140, and the other end passes through the reaction chamber bottom wall 101 and is connected to a transmission mechanism outside the reaction chamber. This allows the mobile grounding ring 140 to move up and down within the reaction chamber 100'. Driven by the transmission mechanism, the metal actuator rod 141 rises or falls, thereby moving the mobile grounding ring 140 up and down. Optionally, there are three metal actuator rods 141, symmetrically distributed along the circumference. Driven by the transmission mechanism, the metal actuator rods 141 rise or fall, thereby moving the mobile grounding ring 140 up and down.

Each metal actuator rod 141 is fitted with a first bellows 142. The first end of each first bellows 142 is fixed to the metal actuator rod 141, and the second end is fixed to the reaction chamber bottom wall 101. When the metal actuator rod 141 moves up or down, the corresponding first bellows 142 is stretched or compressed in the direction of movement. As shown in Figure 2, the first bellows 142 are positioned above the reaction chamber bottom wall 101, i.e., within the reaction chamber 100'. When the movable grounding ring 140 moves upward, the first bellows 142 are stretched; when the movable grounding ring 140 moves downward, the first bellows 142 are compressed.

In other embodiments, the first bellows 142 may be disposed below the reaction chamber bottom wall 101, i.e., outside the reaction chamber 100'. In this case, when the movable ground ring 140 moves upward, the first bellows 142 is compressed; when the movable ground ring 140 moves downward, the first bellows 142 is stretched.

To prevent RF signal leakage and electrically connect the mobile ground ring 140 to the reaction chamber 100', the first bellows 142 should be made of metal, optionally stainless steel. The good contact between the metal actuator rod 141, the first bellows 142, and the reaction chamber bottom wall 101 achieves effective grounding and prevents RF leakage.

In conventional technology, since the structure inside the reaction chamber 100 is fixed, the inherent capacitance between the lower electrode assembly 111 and the ground ring 132 is constant at C ₀ , and the total capacitance of the chamber and the resonance frequency of the chamber are also fixed accordingly. In this embodiment, by installing the aforementioned movable ground ring 140 between the lower electrode assembly 111 and the ground ring 132, a first parallel plate capacitor _C1 is added to the reaction chamber 100' in parallel with the chamber's inherent capacitance C0 _. As the movable ground ring 140 moves up and down, the relative distance between the two plates changes, thereby varying the magnitude of the first parallel plate capacitor _C1 within a certain range. This also changes the capacitance of the lower electrode assembly to ground, and consequently, the chamber's resonant frequency within a certain range, thereby achieving a plasma processing device with adjustable resonant frequency.

Optionally, the area between the movable grounding ring 140 and the lower electrode assembly 111 is 1000-70000 mm ² , and the adjustable relative distance between the movable grounding ring 140 and the lower electrode assembly 111 is 0.1-20 mm.

In another embodiment, since a push pin for lifting the wafer is usually provided in the lower electrode assembly 111, and the number of the push pins is usually three, in order to provide sufficient space for the push pins, the movable ground ring 140 may further include a plurality of metal fan rings, and the number of the fan rings may be three. The gap between each fan ring can accommodate the push pin, so that the push pin can be smoothly raised and lowered. These fan rings are arranged with circumferential frequency guide rods 150, which can be of the same or different sizes and central angles. The lower surface of each fan ring is connected to at least one metal actuator rod 141 that passes through the bottom wall 101 of the reaction chamber. Each metal actuator rod 141 is connected to the bottom wall 101 of the reaction chamber or the grounding ring 132 via a first corrugated tube 142, thereby grounding the corresponding fan ring. Outside the reaction chamber, each metal actuator rod 141 is also connected to a corresponding transmission mechanism. Each fan ring is roughly parallel to the lower surface of the lower electrode assembly 111, forming a second parallel plate capacitor _C2 . Multiple fan rings and the lower surface of the lower electrode assembly 111 form multiple second parallel plate capacitors _C2 . Since the fan rings can be of the same or different sizes, the sizes of the second parallel plate capacitors _C2 can be the same or different. Multiple second parallel plate capacitors _C2 are connected in parallel with the cavity's inherent capacitance _C0 , changing the total capacitance of the lower electrode assembly 111 to ground, thereby changing the total capacitance and resonant frequency of the cavity.

Multiple drive mechanisms control the vertical movement of corresponding fan rings, not only adjusting the size of the multiple second parallel plate capacitors, thereby adjusting the cavity's resonant frequency, but also adjusting the plasma distribution between the upper and lower electrodes. By moving the corresponding fan ring up and down, the capacitance between the fan ring and the lower electrode assembly 111 is adjusted, thereby adjusting the plasma concentration in the corresponding plasma processing area.

In some other embodiments, to expand the capacitance adjustment window, the capacitance adjustment device is a motor capacitor. One end of the motor capacitor is electrically connected to the bottom electrode assembly 111, and the other end is electrically connected to the reaction chamber bottom wall 101 or the ground ring 132 via a wire, ensuring good contact and grounding between the motor capacitor and the reaction chamber bottom wall 101 or the ground ring 132. This motor capacitor can increase the capacitance adjustment range of the bottom electrode assembly 111 relative to ground. Optionally, to improve RF transmission uniformity, the motor capacitor is connected to a feed ring via multiple RF transmission lines, and the feed ring is electrically connected to the bottom electrode assembly 111 via multiple RF transmission lines. Optionally, there are three RF transmission lines between the motor capacitor and the feed ring, and the three RF transmission lines are symmetrically distributed in the circumferential direction; and there are three RF transmission lines between the feed ring and the lower electrode assembly 111, and the three RF transmission lines are symmetrically distributed in the circumferential direction.

In another embodiment, as shown in FIG3 , a metal movable ground sleeve 143 is provided between the RF guide rod 150 and the ground ring 132 as a capacitance adjustment device. The movable ground sleeve 143 surrounds the RF guide rod 150 and is coaxial with the RF guide rod 150. The inner wall of the movable ground sleeve 143 is substantially parallel to the RF guide rod 150. The inner wall of the movable ground sleeve 143 and the RF guide rod 150 form a third parallel plate capacitor C ₃ . The third parallel plate capacitor C ₃ and the cavity inherent capacitance C 3 between the lower electrode assembly 111 and the ground ring 132 in the reaction chamber are ₀ in parallel, the first end of the movable ground sleeve 143 is arranged above the bottom wall 101 of the reaction chamber and below the lower electrode assembly 111, and the second end passes through the bottom wall 101 of the reaction chamber and is arranged outside the reaction chamber. Since only the capacitance between the movable ground sleeve 143 and the RF guide rod 150 in the reaction chamber affects the third parallel plate capacitance _C3 between the movable ground sleeve 143 and the RF guide rod 150, Therefore, by moving the movable ground sleeve 143 up and down, the length of the movable ground sleeve 143 in the reaction chamber is changed, thereby adjusting the relative area between the movable ground sleeve 143 and the RF guide rod 150, thereby changing the capacitance of the RF guide rod 150 to ground, thereby changing the resonant frequency of the cavity.

The movable grounding sleeve 143 is connected to the reaction chamber bottom wall 101 via a second bellows 144. The second bellows 144 is annular, with one end fixedly connected to the reaction chamber bottom wall 101 and the other end fixedly connected to the second end of the movable grounding sleeve 143. The second bellows 144 surrounds the second end of the movable grounding sleeve 143 and is stretched or compressed in the direction of movement of the movable grounding sleeve 143. When the movable grounding sleeve 143 moves upward under the action of the transmission mechanism, the second bellows 144 is compressed. When the movable grounding sleeve 143 moves downward under the action of the transmission mechanism, the second bellows 144 is stretched. The second corrugated tube 144 provides good electrical contact between the movable ground sleeve 143 and the bottom wall 101 of the reaction chamber, while shielding the radio frequency signal within the reaction chamber to prevent leakage.

The movable grounding sleeve 143 is also connected to a metal drive rod outside the reaction chamber. This metal drive rod is connected to a transmission mechanism and provides power for the movable grounding sleeve 143 to move up and down. Optionally, there are three metal drive rods, which are symmetrically distributed in the circumferential direction.

In this embodiment, by installing the movable ground sleeve 143 around the periphery of the RF guide rod, a third parallel plate capacitor _C3 is added to the reaction chamber, connected in parallel with the chamber's inherent capacitance _C0 . As the movable ground sleeve 143 moves up and down, the relative area between the movable ground sleeve 143 and the RF guide rod 150 changes, causing the magnitude of the third parallel plate capacitor _C3 to vary within a certain range. This, in turn, changes the capacitance of the RF guide rod 150 to ground, and consequently, the cavity's resonant frequency to vary within a certain range, thereby achieving a plasma processing device with adjustable resonant frequency.

Optionally, the relative distance between the movable grounding sleeve 143 and the radio frequency guide rod 150 is 0.1-20 mm, and the adjustable relative area between the movable grounding sleeve 143 and the radio frequency guide rod is 1000-12000 mm ² .

In some other embodiments, to expand the capacitance adjustment window, the capacitance adjustment device is a motor capacitor. One end of the motor capacitor is electrically connected to the RF guide rod 150, and the other end is electrically connected to the reaction chamber bottom wall 101 or the ground ring 132 via a wire, ensuring good contact and grounding between the motor capacitor and the reaction chamber bottom wall 101 or the ground ring 132. This motor capacitor can increase the capacitance adjustment range of the RF guide rod 150 to ground. Optionally, to improve RF transmission uniformity, the motor capacitor is connected to a feed ring via multiple RF transmission lines, and the feed ring is electrically connected to the RF guide rod 150 via multiple RF transmission lines. Optionally, there are three RF transmission lines between the motor capacitor and the feed ring, and the three RF transmission lines are symmetrically distributed in the circumferential direction; and there are three RF transmission lines between the feed ring and the RF guide rod 150, and the three RF transmission lines are symmetrically distributed in the circumferential direction.

In other embodiments, other forms of conductive components or variable capacitors may be placed between the lower electrode assembly 111 or the RF guide rod 150 in the reaction chamber and the chamber ground component. Such a capacitor only needs to change the capacitance of the lower electrode assembly 111 or the RF guide rod 150 to ground.

When the cavity's original resonant frequency approaches the used RF frequency, or its multiples or difference frequencies, the plasma processing device with adjustable resonant frequency is used to actively adjust the ground capacitance of the lower electrode assembly or the RF guide rod, thereby changing the cavity's resonant frequency. Because the resonance curve exhibits abrupt changes at the resonant frequency, the desired frequency can be adjusted within a narrow range, such as from a few tenths of a MHz to a few MHz. Furthermore, to adjust the cavity capacitance and thereby alter the resonant frequency, the added capacitance within the cavity (the first parallel plate capacitor _C1 , the total capacitance of multiple second parallel plate capacitors _C2 , the third parallel plate capacitor _C3 , or the motor capacitance) should be several to several hundred times greater than the cavity's inherent capacitance _C0 .

As shown in Figure 4, the device of the present invention is used to change the capacitance of the lower electrode assembly or RF guide rod to ground, shifting the cavity's original resonant frequency of 26.8MHz to 30.5MHz, thus avoiding the multiplication of the RF frequency of 13.56MHz.

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 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 shall be defined by the appended claims.

100’: Reaction Chamber

101: Bottom wall of reaction chamber

111: Bottom electrode assembly

112: Electrostatic Chuck

121: Focus Ring

122: Covering Ring

123: Plasma Confinement Ring

131: Insulation Ring

132: Ground Ring

140: Mobile Ground Ring

141:Metal drive rod

142: First Corrugated Tube

150:RF Guide Rod

Claims (20)

A plasma processing apparatus comprises a reaction chamber formed by a reaction chamber top wall, a reaction chamber bottom wall, and reaction chamber side walls. An upper electrode and a lower electrode assembly opposite the upper electrode are disposed within the reaction chamber. The lower electrode assembly is connected to an RF power supply via an RF guide rod. An RF shielding component is disposed below the lower electrode assembly and surrounds the RF guide rod. A capacitance adjustment device is disposed within the space formed by the RF shielding component, the lower electrode assembly, and the reaction chamber bottom wall. The capacitance between the lower electrode assembly and ground is adjusted by the capacitance adjustment device. A plasma processing device as described in claim 1, wherein the capacitance adjustment device is a movable grounding ring arranged around the RF guide rod, the upper surface of the movable grounding ring is roughly parallel to the lower surface of the lower electrode assembly, and the capacitance between the lower electrode assembly and the ground is adjusted by adjusting the relative distance between the movable grounding ring and the lower electrode assembly. The plasma processing device as described in claim 2, wherein the movable grounding ring is connected to a metal transmission rod extending from the bottom wall of the reaction chamber, and the metal transmission rod drives the movable grounding ring to move up and down in the reaction chamber. The plasma processing device as described in claim 3, wherein the metal transmission rod is connected to the bottom wall of the reaction chamber through a bellows. The plasma processing apparatus of claim 3, wherein the movable grounding ring is connected to three metal drive rods. The plasma processing apparatus of claim 2, wherein an area of the movable grounding ring relative to the lower electrode assembly is 1000-70000 mm ² . A plasma processing device as described in claim 6, wherein the adjustable relative distance between the movable grounding ring and the lower electrode assembly is 0.1-20 mm. A plasma processing apparatus as described in claim 2, wherein the movable ground ring includes a plurality of fan rings. The plasma processing device as described in claim 1, wherein the capacitance adjustment device is a motor capacitor, one end of the motor capacitor is electrically connected to the lower electrode assembly, and the other end is grounded. The plasma processing apparatus of claim 9, wherein the motor capacitor is connected to a feed ring via a plurality of radio frequency transmission lines, and the feed ring is electrically connected to the lower electrode assembly. A plasma processing apparatus comprises a reaction chamber formed by a reaction chamber top wall, a reaction chamber bottom wall, and reaction chamber side walls. An upper electrode and a lower electrode assembly opposite the upper electrode are disposed within the reaction chamber. The lower electrode assembly is connected to an RF power supply via an RF guide rod. An RF shielding component is disposed below the lower electrode assembly and surrounds the RF guide rod. A capacitance adjustment device is disposed within the space formed by the RF shielding component, the lower electrode assembly, and the reaction chamber bottom wall. The capacitance between the RF guide rod and ground is adjusted by the capacitance adjustment device. A plasma processing device as described in claim 11, wherein the capacitance adjustment device is a movable grounding sleeve arranged around the RF guide rod, the movable grounding sleeve and the RF guide rod are coaxially arranged, and the capacitance between the RF guide rod and the ground is adjusted by adjusting the relative area between the movable grounding sleeve and the RF guide rod. A plasma processing device as described in claim 12, wherein the movable grounding sleeve is arranged through the bottom wall of the reaction chamber, the first end of the movable grounding sleeve is arranged below the lower electrode assembly and above the bottom wall of the reaction chamber, and the second end of the movable grounding sleeve is arranged below the bottom wall of the reaction chamber. A plasma processing device as described in claim 13, wherein the movable grounding sleeve is connected to the bottom wall of the reaction chamber through a bellows. A plasma processing device as described in claim 14, wherein the movable grounding sleeve is connected to a metal transmission rod, and the metal transmission rod drives the movable grounding sleeve to move up and down in the reaction chamber. The plasma processing device of claim 12, wherein the relative distance between the movable ground sleeve and the radio frequency guide rod is 0.1-20 mm. The plasma processing apparatus of claim 16, wherein the adjustable relative area between the movable ground sleeve and the lower electrode assembly is 1000-12000 mm ² . A plasma processing device as described in claim 15, wherein the movable ground sleeve is connected to three metal transmission rods. The plasma processing device as described in claim 11, wherein the capacitance adjustment device is a motor capacitor, one end of the motor capacitor is electrically connected to the radio frequency guide rod, and the other end is grounded. The plasma processing apparatus of claim 19, wherein the motor capacitor is connected to a feed ring via a plurality of radio frequency transmission lines, and the feed ring is electrically connected to the radio frequency guide rod.