CN115565840A - A plasma processing device and processing method - Google Patents

Abstract

The invention provides a plasma processing device, which comprises a vacuum reaction cavity, wherein a conductive base is arranged in the vacuum reaction cavity; a main RF transmission rod electrically connected to at least one RF power source for applying a first RF signal to the conductive base; disposing an edge ring around the pedestal; an edge radio frequency transmission line is arranged below the edge ring, the edge radio frequency transmission line applies a second radio frequency signal to the edge ring through an impedance adjusting module, and the impedance adjusting module is located in the atmospheric environment below the conductive base and comprises at least one high-voltage-resistant adjustable capacitor assembly; a dielectric sleeve is sleeved on the part, located inside the vacuum reaction cavity, of the edge radio frequency transmission line; the primary radio frequency transmission rod comprises a hollow structure, and the edge radio frequency transmission line is at least partially positioned inside the primary radio frequency transmission rod. The edge radio frequency adjusting mechanism can actively adjust the height of the sheath layer above the edge ring and can adapt to a radio frequency environment with higher voltage.

Description

A plasma processing device and processing method

technical field

The invention relates to the technical field of semiconductor processing, in particular to the technical field of plasma processing with an edge radio frequency adjustment function.

Background technique

Semiconductor chips are increasingly widely used in various electronic devices. The semiconductor chip processing process requires a large number of plasma processors. These processors will perform plasma etching, chemical vapor deposition and other processes on the substrate to be processed. A typical plasma processor usually includes at least one vacuum reaction chamber. A pedestal is arranged under the vacuum reaction chamber to carry the processing substrate. An external RF power supply applies a radio frequency signal to the pedestal to form a radio frequency in the reaction chamber. environment. The vacuum reaction chamber also includes an air inlet device, which transports the process gas to the interior of the reaction chamber according to certain process requirements. The process gas is dissociated into plasma in the radio frequency environment to achieve etching or deposition of the substrate.

In order to achieve the uniformity of substrate processing, an edge ring component needs to be arranged on the periphery of the susceptor. By selecting the material and shape of the edge ring component, the RF energy and temperature distribution coupled to the edge region of the substrate can be changed. The edge ring assembly includes a focus ring, wherein the upper surface of the focus ring is exposed to the plasma above. During plasma processing, the bias RF power is used to control the thickness of the sheath formed on the upper surface of the substrate and the upper surface of the focus ring. The thickness of the sheath determines the energy and direction of the ions in the plasma incident on the substrate. If the edge area of the substrate and the sheath of the focus ring are discontinuously distributed, the etching rate and direction (edge tilting) of the edge area of the substrate will be different from the central area of the substrate, which will reduce the processing uniformity of the substrate and affect the final chip. yield rate.

Since the focus ring is kept in the plasma filled with etching gas for a long time, the material on the surface of the focus ring will inevitably be corroded after a certain period of plasma treatment, so the height of the upper surface of the focus ring will decrease accordingly. It will seriously affect the distribution and shape of the sheath layer in the edge region of the substrate, so the industry needs to develop a new adjustment device to achieve micro-precision adjustment of the RF power distribution in the center of the substrate and the edge region of the substrate, thereby improving the substrate processing process. Uniformity. Optimally, the adjustment device needs to be simple in structure and low in cost, and can be applied to various plasma processing devices.

Contents of the invention

In order to solve the above technical problems, the present invention provides a plasma processing device, including a vacuum reaction chamber, a lower electrode assembly is arranged in the vacuum reaction chamber, and the lower electrode assembly includes a conductive base; a main radio frequency transmission rod , electrically connected with at least one radio frequency power supply, for applying a first radio frequency signal to the conductive base, the main radio frequency transmission rod includes a hollow structure; an edge ring is arranged around the periphery of the lower electrode assembly; an impedance adjustment module , the atmospheric environment below the conductive base, including at least one high-voltage adjustable capacitor component; an edge radio frequency transmission line, applying a second radio frequency signal to the edge ring through the impedance adjustment module, and the edge radio frequency transmission line is located at The vacuum ambient transmission line jacket is provided with a dielectric sleeve, and the peripheral RF transmission line is located at least partially inside the hollow structure of the main RF transmission rod. In the present invention, by setting an edge radio frequency adjustment mechanism under the edge ring, the active adjustment of the radio frequency distribution in the edge area can be realized, and the problem of uneven processing of the edge area and the center area of the wafer caused by the loss of the edge ring with the progress of the process can be compensated.

Optionally, a radio frequency distribution ring is arranged below the edge ring, and the edge radio frequency transmission line is electrically connected to the radio frequency distribution ring.

Optionally, the radio frequency distribution ring is conductive, and includes a conductor material or a semiconductor material.

Optionally, an insulating coating is provided on the surface of the radio frequency distribution ring.

Optionally, a graphite coating is provided above the radio frequency distribution ring.

Optionally, the edge radio frequency transmission line includes a plurality of conductive rods, and the conductive rods are electrically connected to the radio frequency distribution ring uniformly or non-uniformly.

Optionally, the impedance adjustment module includes a plurality of fixed capacitors connected in parallel, and each of the fixed capacitors is correspondingly provided with a high voltage resistant vacuum relay.

Optionally, the impedance adjustment module includes a motor capacitor.

Optionally, the radio frequency power supply includes a radio frequency power supply with a first frequency and a radio frequency power supply with a second frequency.

Optionally, the second radio frequency signal has a second frequency.

Optionally, a radio frequency filter is arranged between the main radio frequency transmission rod and the edge radio frequency transmission line, and the radio frequency filter is used to filter the radio frequency signal of the first frequency.

Optionally, the output voltage of the RF power supply at the second frequency is greater than or equal to 8KV.

Optionally, the output power of the RF power supply at the second frequency is greater than or equal to 10KW.

Optionally, the second frequency is lower than the first frequency.

Optionally, the second frequency is less than or equal to 2 MHz.

Optionally, the second frequency is less than or equal to 1 MHz.

Optionally, a mounting plate is arranged under the conductive base, and the main radio frequency transmission rod is electrically connected to the mounting plate.

Optionally, the dielectric sleeve is made of high-purity ceramics, and the purity of the ceramics is greater than 95%.

Optionally, the distance between the inner diameter of the dielectric sleeve and the edge radio frequency transmission line is less than or equal to 0.3 mm.

Optionally, the dielectric sleeve includes several ceramic spacers, and a concave-convex groove assembly is provided on the joint surface between two adjacent ceramic spacers to prevent breakdown.

Optionally, the edge ring is a focus ring.

Further, the present invention also discloses a plasma processing method with edge impedance adjustment function, the method is carried out in the above-mentioned plasma processing device, and the method includes the following steps:

Substrate etching effect monitoring step: detect the etching effect of the edge area of the substrate, if the inclination angle of the etching hole at the edge of the substrate is within the preset angle range, continue to perform the substrate etching effect detection step, if the etching hole at the edge of the substrate If the tilt exceeds the preset threshold, enter the variable impedance adjustment step;

Variable impedance adjustment step: adjust the capacitance value of the high-voltage adjustable capacitor component, so that the impedance of the impedance adjustment module changes, and then changes the radio frequency power delivered to the edge ring of the substrate, and enters the substrate etching effect monitoring again step.

The present invention sets an edge adjustment mechanism under the edge ring, which specifically includes: setting a radio frequency distribution ring under the focus ring, the radio frequency distribution ring is connected to an edge radio frequency transmission line, and the edge radio frequency transmission line is introduced into a radio frequency signal through a high voltage resistant impedance adjustment module to apply To the radio frequency distribution ring, the radio frequency signal is coupled to the focusing ring through the radio frequency distribution ring, so as to adjust the edge electric field and plasma distribution in the edge region. The impedance adjustment module of the present invention is located in the atmospheric environment outside the vacuum reaction chamber, and can withstand higher radio frequency voltage. At the same time, in order to cooperate with the high pressure environment of the vacuum reaction chamber, the edge radio frequency transmission line is located in the vacuum environment. The transmission line jacket is equipped with high-purity materials A dielectric sleeve to isolate high power signals on the lower electrode assembly.

In addition, at least part of the edge radio frequency transmission line of the present invention is located inside the hollow structure of the main radio frequency transmission rod. Setting the edge radio frequency transmission line inside the hollow main radio frequency transmission rod is beneficial to ensure the symmetry of the high frequency radio frequency power transmission in the circumferential direction. Due to the high frequency skin effect, the high frequency radio frequency current is distributed outside the main radio frequency transmission rod. The edge transmission line is placed inside the hollow main RF transmission rod to minimize the impact on the high frequency RF transmission loop. In addition, since the impedance adjustment module is set outside the vacuum reaction chamber and is far away from the focus ring, by setting the edge RF transmission line drawn from the impedance adjustment module inside the hollow main RF transmission rod, the length of the edge RF transmission line can be set. In order to be shorter, it can simplify the wiring setting under the mounting plate at the same time.

Description of drawings

Fig. 1 shows a schematic diagram of a capacitively coupled plasma processing device;

Figure 2 shows an enlarged schematic view of the edge area of the electrode assembly;

Fig. 3A and Fig. 3B respectively show the schematic diagram of the embodiment of the contact interface between two different radio frequency distribution rings and the focus ring;

Fig. 4 shows a schematic diagram of an inductively coupled plasma processing device.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The plasma processing device described in the technical solution of the present invention may be a capacitively coupled plasma processing device (CCP) or an inductively coupled plasma processing device (ICP). Fig. 1 shows a schematic structural view of a capacitively coupled plasma processing device. As shown in Fig. 1, the plasma processing device has a vacuum reaction chamber 100, the vacuum reaction chamber 100 is substantially cylindrical, and the side wall of the reaction chamber is basically Vertically, the vacuum reaction chamber 100 has an upper electrode assembly 110 and a lower electrode assembly 120 disposed opposite to each other. Generally, the upper electrode assembly 110 includes a shower head for supplying process gas into the reaction chamber 100, and the lower electrode assembly 120 includes a conductive base 122, an electrostatic adsorption layer 124 above the conductive base, and a mounting plate below the conductive base. 126. The electrostatic adsorption layer 124 is used to carry and adsorb the wafer W to be processed during the process. The area between the upper electrode assembly 110 and the lower electrode assembly 120 is a processing area that will generate high frequency energy to ignite and maintain plasma. The process gas is input into the reaction chamber 100 through the shower head of the upper electrode assembly 110, and one or more radio frequency power sources can be applied to the lower electrode assembly 120 separately or applied to the upper electrode assembly 110 and the lower electrode assembly 120 respectively. , so that a large electric field is generated inside the reaction chamber 100 . In the embodiment shown in FIG. 1 , the RF signal output by the RF power supply 150 is applied to the mounting board 126 via the matching circuit 152 and a hollow main RF conductive rod 154 .

Most of the electric field is contained in the processing region between the upper electrode assembly 110 and the lower electrode assembly 120, and the electric field accelerates a small number of electrons existing inside the reaction chamber to collide with gas molecules of the input reaction gas. These collisions result in ionization of the reaction gas and excitation of plasma, thereby generating plasma within the reaction chamber 100 . The neutral gas molecules of the reactive gas lose electrons when subjected to these strong electric fields, leaving behind positively charged ions. Positively charged ions are accelerated toward the lower electrode assembly 120, combine with neutral substances in the wafer to be processed, and stimulate wafer processing, ie, etching, deposition, and the like.

An exhaust area is provided at a suitable position of the plasma processing device, and the exhaust area is connected with an external exhaust device (not shown in the figure) to remove the used reaction gas and by-product gas during the treatment process. The treatment area is pumped out, the gas flows through and the proper pressure is established in the treatment area.

FIG. 2 shows an enlarged schematic view of the edge area of the lower electrode assembly. At least one edge ring is usually arranged around the lower electrode assembly 120 for adjusting parameters such as electric field distribution or temperature in the edge area, wherein an edge ring exposed to the plasma processing area It is a focus ring 130 (focus ring), and a coupling ring 133 is arranged below the focus ring. The focus ring 130 is usually made of insulating materials such as quartz and alumina or semiconductor materials such as silicon carbide and silicon, so as to avoid contamination of the substrate by particles generated during plasma processing and provide sufficient electrical conductivity. However, with the repetition of the plasma treatment process, the erosion of the focus ring caused by ion bombardment deepens, and the thickness of the focus ring becomes thinner, resulting in a change in the height of the plasma sheath above the focus ring, resulting in The ion directionality of the region changes. Therefore, the etching pattern in the edge region of the wafer cannot be formed vertically and a titling phenomenon occurs.

The present invention sets an edge adjustment mechanism under the focus ring, which specifically includes: setting a radio frequency distribution ring 180 under the focus ring, the radio frequency distribution ring 180 is connected to an edge radio frequency transmission line 140, and the edge radio frequency transmission line 140 is introduced into a radio frequency through an impedance adjustment module 160 The signal is applied to the radio frequency distribution ring 180 , and the radio frequency signal is coupled to the focusing ring through the radio frequency distribution ring to adjust the fringe electric field and plasma distribution in the fringe region.

In the embodiment shown in FIG. 1 , the impedance adjustment module 160 includes several fixed capacitors 162 connected in parallel and a high-voltage-resistant vacuum relay 164 that matches the fixed capacitors. The vacuum relay realizes the switching and on-off of the fixed capacitors by controlling the power supply. , to determine the value of the capacitor connected to the impedance adjustment module. The impedance adjustment module 160 can withstand higher radio frequency voltage. For example, when the radio frequency power output by the radio frequency power supply is greater than 20kw, the impedance adjustment module can still ensure stable operation. Due to the large volume of the high voltage vacuum relay, the present invention arranges the impedance adjustment module 160 in the atmospheric environment below the mounting plate 126 . In the present invention, the edge radio frequency transmission line 140 includes a transmission line 142 located in an atmospheric environment and a transmission line 141 located in a vacuum environment. Since the edge adjustment mechanism of the present invention has the characteristics of high-voltage resistance to radio frequency, the transmission line 141 located in a vacuum environment also has high-voltage resistance. specialty.

In order to ensure that the transmission line 141 in the vacuum environment can withstand higher voltage, the part of the edge radio frequency transmission line inside the vacuum reaction chamber is covered with a dielectric sleeve 145 to realize the electrical isolation of the edge radio frequency transmission line and the lower electrode assembly. The dielectric sleeve 145 can be a high-purity ceramic sleeve, and the purity of the ceramic is greater than 95%. In other embodiments, the dielectric sleeve 145 can also be other insulating materials. Due to mechanical tolerances and considering factors such as thermal expansion and assembly, there may be a gap between the transmission line 141 in the vacuum environment and the dielectric sleeve 145 . In order to avoid ignition that may occur between the gaps, the distance between the inner diameter of the dielectric sleeve and the edge radio frequency transmission line is less than or equal to 0.3 mm. In some embodiments, for the convenience of installation, the edge radio frequency transmission line can be set in several sections, the dielectric sleeve includes several ceramic spacers, and a concave-convex groove assembly is provided on the joint surface between two adjacent ceramic spacers, so as to Increase creepage distance to prevent breakdown.

A part of the low-frequency radio frequency signal output by the matching circuit 152 is applied to the lower electrode assembly through the main radio frequency transmission rod 154, and the other part is supplied to the radio frequency distribution ring 180 through the edge radio frequency transmission line 140 through the impedance adjustment module 160, wherein at least part of the edge output from the impedance adjustment module The radio frequency transmission line is located inside the hollow structure of the main radio frequency transmission rod. Setting the edge radio frequency transmission line 140 inside the hollow main radio frequency transmission rod is beneficial to ensure the symmetry of the high frequency radio frequency power transmission in the circumferential direction. Due to the high frequency skin effect, the high frequency radio frequency current is distributed outside the main radio frequency transmission rod. The edge transmission line is placed inside the hollow main RF transmission rod to minimize the impact on the high frequency RF transmission loop. In addition, since the impedance adjustment module 160 is arranged outside the vacuum reaction chamber and is far away from the focus ring, by setting the edge radio frequency transmission line drawn from the impedance adjustment module 160 inside the hollow main radio frequency transmission rod 154, the edge radio frequency transmission line can be The length is set to be shorter, and at the same time the line setting under the mounting plate 126 can be simplified.

The edge radio frequency transmission line The transmission line 142 located in the atmospheric environment can be a continuous wire, and the transmission line 141 located in the vacuum environment can be set as several sections of conductive rods due to the needs of installation, and the electrical connections between the several sections of conductive rods are kept. A dielectric sleeve is provided for electrical isolation from the lower electrode assembly. In this embodiment, the radio frequency signal output by the transmission line 142 located in the atmospheric environment can be applied to different positions of the radio frequency distribution ring through several conductive rods, and the distribution of the multiple conductive rods can be uniform or non-uniform to improve the uniformity of the radio frequency distribution. or can be tuned to be non-uniform at different phase angles. In another embodiment, the radio frequency signal output by the transmission line 142 located in the atmospheric environment can also be applied to the radio frequency distribution ring through only one conductive rod, which can be selected according to actual needs.

The transmission line 141 located in the vacuum environment can be applied upwards to the radio frequency distribution ring 180 through the mounting plate 126 and the conductive base 122 as shown in FIG. between isolation rings 134 .

In the embodiment shown in FIG. 2, the RF power supply 150 includes a high-frequency power supply 1510 and a low-frequency power supply 1520. The high-frequency power supply 1510 applies a high-frequency radio frequency signal to the lower electrode assembly 120 through a high-frequency matching circuit 1512, and is mainly used to transfer the process gas Excited as a plasma, controlling the density of the plasma. The low-frequency power supply 1520 applies a low-frequency radio frequency signal to the lower electrode assembly 120 through the low-frequency matching circuit 1522, which is mainly used to control the thickness of the plasma sheath on the surface of the substrate. In the embodiment shown in FIG. 2 , the low frequency RF signal applied to the focus ring and the low frequency RF signal applied to the lower electrode assembly 120 share the same RF power supply 1520 . In another embodiment, an edge radio frequency power supply may also be separately provided to apply radio frequency signals to the focus ring 130 . Optionally, the second frequency, that is, the output frequency of the low-frequency radio frequency power supply 1520 is less than or equal to 2 MHz. Optionally, the second frequency, that is, the output frequency of the low-frequency radio frequency power supply is less than or equal to 1 MHz.

The inventors found that when high-frequency radio-frequency power is applied to the lower electrode assembly 120, the radio-frequency power can be easily coupled to the focus ring, because the surface of the lower electrode assembly 120 is very thin (tens of microns) for high-frequency signals. The resistance of the insulating corrosion-resistant layer and the coupling ring 133 is very small. But for low-frequency RF signals, the lower frequency causes the same insulating layer and coupling ring 133 to form a large impedance, which results in only a small amount of low-frequency RF energy being coupled to the focus ring 130, even if various means are used. Adjust the dielectric constant and position of the coupling ring and the focus ring, and the final adjustable range is still limited. Because the insulating and corrosion-resistant layer on the side wall of the conductive base 122 is essential, and the coupling ring is usually made of insulating materials, such as aluminum oxide or silicon oxide, it is impossible to distribute the low-frequency radio frequency power adjustable under the existing hardware structure. onto the focus ring 130 at the edge of the substrate. Among them, the coupling ring can also be made of highly conductive materials, but this coupling ring can only achieve a good etching effect in a short period of time, and it still cannot compensate the drift of the processing effect caused by the loss of the focus ring over a long period of time. Moreover, in addition to affecting the distribution of low-frequency RF power, the high-conductivity coupling ring will also affect the distribution of high-frequency RF power, which also affects the distribution of plasma concentration. Even, it does not improve the overall plasma treatment effect.

The present invention actively applies low-frequency radio frequency signals that are difficult to couple to the edge area under the focus ring by setting up an edge adjustment mechanism, and realizes active adjustment of circuit impedance by connecting an impedance adjustment module 160, and selects fixed capacitors of different gears 162 capacitor value to adjust the low frequency RF power delivered to the focus ring. The impedance adjustment module in the present invention is set in the atmospheric environment below the lower electrode assembly 120, including fixed capacitors with several gears and high-voltage-resistant vacuum relays, which can withstand the high voltage output by the radio frequency power supply, so as to adapt to the ever-increasing height, depth and width. Higher RF voltage requirements than etch processes. The edge adjustment mechanism of this embodiment can withstand the radio frequency environment with an output power greater than or equal to 10KW and an output voltage greater than or equal to 8KV. In order to prevent high-frequency radio frequency signals from entering the edge radio frequency transmission line 140, causing problems such as overheating through the edge radio frequency transmission line 140, a radio frequency filter can be set on the edge radio frequency transmission line 140, that is, a filter inductor 170. Optionally, the range of the filter inductor It can be 0-10 microhenries, and the filter inductance can prevent the high-frequency radio frequency signal in the vacuum reaction chamber from being transmitted downwards through the edge radio frequency transmission line 140 and burn the edge radio frequency transmission line 140 .

Fig. 3 A and Fig. 3 B respectively show the embodiment schematic diagram of the contact interface between two kinds of different radio frequency distribution rings and the focus ring, in the embodiment shown in Fig. 3 A, the focus ring is placed above the radio frequency distribution ring 180, because the focus ring The material is usually made of insulating materials such as quartz and alumina or semiconductor materials such as silicon carbide and silicon. The radio frequency distribution ring is usually made of conductive materials such as aluminum or aluminum alloy or semiconductor materials. Both of them have certain rigidity, so When the two are in contact, in order to avoid inconsistent distances between different contact areas, resulting in uneven radio frequency distribution, therefore, a layer of insulating coating 183 is provided on the surface of the radio frequency distribution ring 180. Exemplarily, when the radio frequency distribution ring 180 is made of aluminum or aluminum alloy material, the insulating coating 186 can be aluminum oxide, to form a capacitor between the radio frequency distribution ring 180 and the focus ring 130, to ensure that the capacitance between the different contact areas of the focus ring and the radio frequency distribution ring is consistent, so that the Focus ring surfaces at different phase angles form sheaths of the same height.

In the embodiment shown in FIG. 3B , a cover ring 132 is provided on the outer edge of the focus ring 130 , and the cover ring 132 is mechanically locked to the coupling ring below, so good electrical contact can be ensured between the bottom surface of the focus ring and the RF distribution ring. At this time, a graphite layer 182 is arranged above the radio frequency distribution ring, and a layer of metal material 184 such as aluminum or aluminum alloy can be buried inside the graphite layer 182 to maintain the mechanical strength of the graphite layer. The graphite layer has good electrical conductivity and a certain degree of flexibility, which can ensure that the radio frequency on the radio frequency distribution ring 180 is evenly applied to the focusing ring in the entire annular area, ensuring the uniformity of the radio frequency signal distribution at all angles and improving the radio frequency signal. transmission efficiency.

FIG. 4 shows a schematic structural view of an inductively coupled plasma processing device. The plasma processing device shown in FIG. 4 has a reaction chamber 200, which is different from the capacitively coupled plasma reaction chamber 100 described in FIG. It is a device that passes the energy of the radio frequency power supply into the reaction chamber in the form of magnetic field coupling through the inductance coil, so as to generate plasma and use it for etching. The inductively coupled plasma reaction device includes a vacuum reaction chamber 200, the vacuum reaction chamber includes a substantially cylindrical reaction chamber side wall made of metal material, an insulating window 210 is arranged above the reaction chamber side wall, and an inductor is arranged above the insulating window 210. The coupling coil 212 and the inductive coupling coil 140 are connected to the radio frequency power supply 2510 through the matching circuit 2512 .

A gas injection port 214 is provided on the side wall of the reaction chamber close to the insulating window 210. In some equipment, a gas injection port is also provided in the central area of the insulating window 210. The reaction gas enters the vacuum reaction chamber 200 through the gas injection port 214. The RF power drives the inductively coupled coil 212 to generate a strong high-frequency alternating magnetic field, so that the low-pressure reaction gas is ionized to generate plasma. The lower electrode assembly 220 is arranged at the downstream position of the vacuum reaction chamber 200. The lower electrode assembly 220 has a structure similar to that of the lower electrode assembly 120 in the capacitively coupled plasma processing device shown in FIG. An electrostatic adsorption layer 224 above the base and a mounting plate 226 under the conductive base. The electrostatic adsorption layer is used to carry and absorb the wafer W to be processed during the process. Plasma contains a large number of active particles such as electrons, ions, excited atoms, molecules, and free radicals. The above-mentioned active particles can undergo various physical and chemical reactions with the surface of the substrate to be treated, causing the morphology of the substrate surface to change. change, the etching process is completed.

In this embodiment, the RF power supply 2520 applied to the lower electrode assembly is a bias RF power supply, and its frequency is usually lower than that of the RF power supply 2510. The low-frequency RF signal output by the RF power supply 2520 passes through the matching circuit 2522 and a hollow RF conduction The rod 254 is applied to the mounting plate 226 to control the distribution of the sheath layer on the surface of the wafer. At the same time, according to the above description, the present invention also provides an edge adjustment mechanism to actively apply low-frequency radio frequency signals that are difficult to couple to the edge area to the focus ring 230, and by connecting an impedance adjustment module 260 to realize the active adjustment of the circuit impedance, optionally, a motor capacitor is set in the impedance adjustment module 260 of this embodiment to perform impedance on the low-frequency radio frequency signal applied to the focus ring adjust. The motor capacitor can withstand higher voltage, and at the same time, it can realize continuous adjustment between 0-100% of the capacitor, with high adjustment accuracy. It is easy to understand that the impedance adjustment module 260 in this embodiment can also be applied to the capacitively coupled plasma processing device shown in FIG. 1, and similarly, the impedance adjustment module 160 in FIG. 1 can also be applied to the inductor coupled to the plasma processing unit.

Similar to the above embodiments, the edge radio frequency transmission line 240 includes a transmission line 241 located in a vacuum environment and a transmission line 242 located in an atmospheric environment. The setting requirements of the edge RF transmission line and the settings of the RF distribution ring are the same as those described above, and will not be repeated here.

The present invention also discloses a plasma processing method with an edge impedance adjustment function, the method is carried out in any plasma processing device described in Figure 1 or Figure 4, and the method includes the following steps:

Substrate etching effect monitoring step: detect the etching effect of the edge area of the substrate, if the inclination angle of the etching hole at the edge of the substrate is within the preset angle range, continue to perform the substrate etching effect detection step, if the etching hole at the edge of the substrate If the tilt exceeds the preset threshold, enter the variable impedance adjustment step;

Variable impedance adjustment step: adjust the capacitance value of the high-voltage adjustable capacitor component, so that the impedance of the impedance adjustment module changes, and then changes the radio frequency power delivered to the edge ring of the substrate, and enters the substrate etching effect monitoring again step.

It is an optional embodiment that the impedance adjustment module described in the present invention is set as an adjustable capacitor, but other variable impedance devices that can be switched to low-frequency radio frequency power impedance, such as those composed of variable inductors and capacitors A hybrid circuit or a circuit composed of other components can realize the function of impedance adjustment, and the above replacements belong to common knowledge, so they will not be listed one by one.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as limiting the present invention. Various modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the above disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (22)

1. A plasma processing device, characterized in that: comprising: A vacuum reaction chamber, a lower electrode assembly is arranged in the vacuum reaction chamber, and the lower electrode assembly includes a conductive base; The main radio frequency transmission rod is electrically connected to at least one radio frequency power supply, and is used to apply the first radio frequency signal to the conductive base, and the main radio frequency transmission rod includes a hollow structure; an edge ring disposed around the lower electrode assembly; An impedance adjustment module, located in the atmosphere below the conductive base, includes at least one high-voltage adjustable capacitor component; An edge radio frequency transmission line, the second radio frequency signal is applied to the edge ring through the impedance adjustment module, the edge radio frequency transmission line is located in a vacuum environment, the transmission line is covered with a dielectric sleeve, and the edge radio frequency transmission line is located in an atmospheric environment. At least partially within the hollow structure of the main RF transmission rod. 2 . The plasma processing apparatus according to claim 1 , wherein a radio frequency distribution ring is arranged below the edge ring, and the edge radio frequency transmission line is electrically connected to the radio frequency distribution ring. 3 . 3 . The plasma processing device according to claim 2 , wherein the radio frequency distribution ring has conductivity and comprises a conductor material or a semiconductor material. 4 . 4. The plasma processing device according to claim 2, wherein an insulating coating is provided on the surface of the radio frequency distribution ring. 5. The plasma processing device according to claim 2, wherein a graphite coating is arranged above the radio frequency distribution ring. 6 . The plasma processing apparatus according to claim 2 , wherein the edge radio frequency transmission line comprises a plurality of conductive rods, and the conductive rods are electrically connected to the radio frequency distribution ring uniformly or non-uniformly. 7. The plasma processing device according to any one of claims 1-6, wherein the impedance adjustment module includes a plurality of fixed capacitors connected in parallel, and each of the fixed capacitors is correspondingly provided with a high-voltage-resistant vacuum relay. 8. The plasma processing apparatus according to claims 1-6, wherein the impedance adjustment module comprises a motor capacitor. 9. The plasma processing apparatus according to claims 1-6, wherein the radio frequency power source comprises a radio frequency power source with a first frequency and a radio frequency power source with a second frequency. 10. The plasma processing apparatus as claimed in claim 9, wherein the second radio frequency signal has a second frequency. 11. The plasma processing device according to claim 9, wherein a radio frequency filter is arranged between the main radio frequency transmission rod and the edge radio frequency transmission line, and the radio frequency filter is used to filter the first frequency radio frequency signal. 12. The plasma processing apparatus according to claim 9, wherein the output voltage of the RF power supply at the second frequency is greater than or equal to 8KV. 13. The plasma processing apparatus according to claim 9, wherein the output power of the radio frequency power supply at the second frequency is greater than or equal to 10KW. 14. The plasma processing apparatus as claimed in claim 9, wherein the second frequency is lower than the first frequency. 15. The plasma processing apparatus according to claim 9, wherein the second frequency is less than or equal to 2 MHz. 16. The plasma processing apparatus according to claim 9, wherein the second frequency is less than or equal to 1 MHz. 17. The plasma processing apparatus according to claim 1, wherein a mounting plate is arranged under the conductive base, and the main radio frequency transmission rod is electrically connected to the mounting plate. 18. The plasma processing apparatus according to claim 1, wherein the dielectric sleeve is made of high-purity ceramics, and the purity of the ceramics is greater than 95%. 19. The plasma processing apparatus according to claim 1, wherein the distance between the inner diameter of the dielectric sleeve and the edge radio frequency transmission line is less than or equal to 0.3 mm. 20. The plasma processing device according to claim 1, characterized in that: the dielectric sleeve includes several ceramic spacers, and a concave-convex groove assembly is provided on the joint surface between two adjacent ceramic spacers to prevent breakdown. 21. The plasma processing apparatus of claim 1, wherein the edge ring is a focus ring. 22. A plasma processing method with edge impedance adjustment function, characterized in that the method is carried out in the plasma processing device according to any one of claims 1-21, and the method comprises the following steps: Substrate etching effect monitoring step: detect the etching effect of the edge area of the substrate, if the inclination angle of the etching hole at the edge of the substrate is within the preset angle range, continue to perform the substrate etching effect detection step, if the etching hole at the edge of the substrate If the tilt exceeds the preset threshold, enter the variable impedance adjustment step; Variable impedance adjustment step: adjust the capacitance value of the high-voltage adjustable capacitor component, so that the impedance of the impedance adjustment module changes, and then changes the radio frequency power delivered to the edge ring of the substrate, and enters the substrate etching effect monitoring again step.

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