Cavity wall potential controllable radio frequency magnetron sputtering device and potential control method thereof

Abstract

This application discloses a radio frequency magnetron sputtering device with controllable cavity wall potential and its potential control method. The magnetron sputtering device includes a sputtering source cavity, a target material, a working cavity, a shield, and an active potential controller. The sputtering source cavity and the working cavity are sealed together, forming a process cavity. The target material is connected to a radio frequency power supply, which can output a periodically changing radio frequency electric field. Each cycle of the radio frequency electric field includes a positive half-cycle and a negative half-cycle. The shield is made of conductive material and is used to define the deposition area of ​​sputtered particles. The active potential controller is electrically connected to the shield and is used to apply a potential to the shield so that the shield can repel positively charged particles at least during the positive half-cycle, thereby suppressing particle adhesion on the shield. By using a constant positive potential or a periodic variable potential mode synchronized with the radio frequency, the negative potential during the negative half-cycle is strictly controlled below the particle re-sputtering threshold, thus fundamentally preventing the particle contamination problem caused by thin film deposition and peeling on the shield surface.

Description

Technical Field

[0001] This application relates to the field of magnetron sputtering technology, and in particular to a radio frequency magnetron sputtering device with controllable cavity wall potential and its potential control method. Background Technology

[0002] Radio frequency (RF) magnetron sputtering is a key technology for preparing non-conductive thin films (such as ITO and PZT). Its basic principle is that the target is connected to an RF power supply, and the RF electric field creates a negative self-bias on the surface of the insulating target, attracting positive ions to bombard the target and achieve sputtering deposition. Each cycle of the RF electric field includes a positive half-cycle and a negative half-cycle. During the negative half-cycle, the target attracts positive ions for sputtering, while during the positive half-cycle, the target surface charge is neutralized and arcing is suppressed.

[0003] In existing RF magnetron sputtering apparatuses, the cavity sidewalls of the working chamber and the annular shield located below the target are typically directly grounded or at a floating potential. However, during the negative half-cycle, the plasma potential rises, causing the grounded shield to have a negative potential relative to the plasma. This attracts positive ions to bombard the shield surface, causing secondary sputtering of the film already deposited on the shield and generating a large number of micron-sized particulate contaminants. During the positive half-cycle, the shield potential passively floats and cannot effectively repel positively charged particles. The particles still adhere to the shield surface, and over time, the film becomes loose and peels off, further exacerbating particulate contamination. These particles fall into the thin film on the wafer surface, severely reducing coating quality and yield, and making it particularly difficult to meet the stringent cleanliness requirements of high-end semiconductor devices and precision optical coatings. Summary of the Invention

[0004] The purpose of this application is to overcome the shortcomings of the prior art and provide a radio frequency magnetron sputtering device with controllable cavity wall potential and a potential control method thereof.

[0005] This application provides a radio frequency magnetron sputtering apparatus with controllable cavity wall potential, comprising: a sputtering source cavity 1 for mounting a target 10, the target 10 being connected to a radio frequency power supply, the radio frequency power supply being able to output a periodically changing radio frequency electric field, each cycle of the radio frequency electric field including a positive half-cycle and a negative half-cycle; a working cavity 2 connected to the sputtering source cavity 1, the working cavity 2 having a lifting stage for supporting a wafer, the target 10 facing the lifting stage; a shield 20 made of conductive material, arranged in a ring shape, disposed in the working cavity 2, located below the target 10, and surrounding the sputtering surface of the target 10, for abutting against the wafer on it when the lifting stage is raised, thereby defining the deposition area of ​​sputtered particles; and an active potential controller 30 electrically connected to the shield 20, for applying a potential to the shield 20, such that the shield 20 is at least in a positive... During the half-cycle, it can repel positively charged particles, thereby suppressing the attachment of particles on the shield 20; the active potential controller 30 is configured to keep the shield 20 at a positive potential, and the active potential controller 30 is used to apply a constant positive DC bias voltage to the shield 20. The value of the positive DC bias voltage is set to be higher than the maximum fluctuation value of the plasma potential during the radio frequency discharge process, so that a stable electrostatic barrier that repels positive ions is always formed on the surface of the shield 20 throughout the entire radio frequency cycle; or, the active potential controller 30 is configured to make the potential of the shield 20 change periodically in sync with the radio frequency power supply. In the positive half-cycle, the shield 20 presents a positive potential, and in the negative half-cycle, the shield 20 presents a negative potential, and the absolute value of the negative potential is configured to be less than the threshold value that can attract positive ions to bombard the particles attached to the shield 20.

[0006] Furthermore, when the active potential controller 30 is configured to keep the shield 20 continuously at a positive potential, the active potential controller 30 includes: a DC bias power supply for continuously applying a constant positive DC voltage to the shield 20 so that the shield 20 is always at a positive potential throughout the entire cycle of the radio frequency electric field; and a filter network connected between the DC bias power supply and the shield 20 for preventing radio frequency energy from entering the DC bias power supply.

[0007] Furthermore, when the active potential controller 30 is configured to cause the potential of the shield 20 to change periodically in sync with the RF power supply, the active potential controller 30 includes: an adjustable impedance matching network connected between the shield 20 and a reference ground, including a fixed inductor L1 and an adjustable capacitor C, for adjusting the RF impedance of the shield 20 so that the potential of the shield 20 changes periodically in sync with the RF power supply; a DC bias power supply connected to the shield 20 through an isolation inductor L2, for providing a programmable DC bias voltage to the shield 20; a VI sensor connected between the shield 20 and the adjustable impedance matching network, for measuring in real time the RF current flowing through the shield 20, the voltage to ground, and their phase difference; and a controller connected to the VI sensor, the adjustable capacitor C, and the DC bias power supply, for closed-loop control of the capacitance value of the adjustable capacitor C and / or the output of the DC bias power supply based on the measurement results of the VI sensor, thereby dynamically maintaining the preset potential waveform of the shield 20.

[0008] Furthermore, the active potential controller 30 also includes an ion energy analyzer, which is disposed adjacent to the shield 20 and is used to measure the positive ion energy distribution and ion flux density bombarding the surface of the shield 20 in real time. The controller is connected to the ion energy analyzer and is configured to reduce the absolute value of the negative bias voltage of the shield 20 or increase the positive bias voltage of the shield 20 when the ion energy analyzer detects that the ion energy on the surface of the shield 20 exceeds a preset critical sputtering threshold. And / or, the active potential controller 30 also includes a plasma potential probe, which is disposed within the working cavity 2 and is used to measure the plasma potential in real time. The controller is connected to the plasma potential probe and is configured to measure the plasma potential based on the plasma potential and... The preset potential waveform of the shield 20 is dynamically adjusted based on the difference in reference ground potential to ensure that the absolute value of the negative potential of the shield 20 during the negative half-cycle is always less than the difference, thereby avoiding the attraction of high-energy positive ion bombardment; and / or, the sampling rate of the VI sensor is not less than 50MHz, used to acquire the instantaneous waveforms of the RF voltage and current on the shield 20, and the controller is configured to calculate the actual potential peak value of the shield 20 in each RF cycle based on the instantaneous waveform, and compare it with the preset target waveform to correct the capacitance value of the adjustable capacitor C and / or the output of the DC bias power supply; and / or, the active potential controller 30 also includes an arc detection module, which is connected to the VI sensor to monitor the rate of change of voltage on the shield 20 and / or current spikes to identify arc events. The controller is connected to the arc detection module and configured to forcibly switch the potential of the shield 20 to a preset positive safe potential within microseconds when an arc event is detected, and restore the preset target waveform after the arc is extinguished; and / or, the VI sensor is configured to extract the harmonic components of the RF power supply operating frequency, including the second harmonic and / or the third harmonic. The controller is configured to analyze the amplitude and phase changes of the harmonic components to diagnose the microstate of the plasma, and to warn that the negative potential of the shield 20 may exceed the critical threshold when abnormal changes occur in the harmonic components; and / or, the active potential controller 30 also includes a dual-channel redundant measurement unit, the dual-channel redundant measurement The measurement unit includes two independently configured VI sensors, which are respectively arranged at different positions or different electrical connection points of the shield 20. The controller is connected to the two VI sensors and is configured to cross-verify the two measurement data. When the deviation between the two data exceeds a preset threshold, it is judged as a sensor fault and the potential of the shield 20 is automatically switched to a conservative safety mode, which is a continuous positive potential. And / or, the adjustable capacitor C is a piezoelectric ceramic driven vacuum variable capacitor with an adjustment accuracy of ±0.1pF. And / or, the DC bias power supply is a programmable DC power supply with a resolution of 16 bits or higher. And / or, the controller is a field programmable gate array with a control cycle of no more than 1 microsecond.

[0009] Furthermore, insulating structures are provided between the shield 20 and the sputtering source cavity 1, and between the shield 20 and the working cavity 2, to prevent the potential on the shield 20 from leaking to other grounded or floating components; and / or, the shield 20 and the target 10 are electrically isolated by a physical gap, the distance of which is configured to be greater than the Paschen breakdown distance corresponding to the maximum potential difference between the shield 20 and the target 10, so as to avoid gas breakdown. The upper end face of the shield 20 is higher than the sputtering surface of the target 10, so that the gap between the two is located within the line-of-sight deposition shadow area of ​​the sputtered particle stream of the target 10, thereby avoiding electrical short circuits caused by the deposition of conductive films in the physical gap.

[0010] Furthermore, the RF magnetron sputtering device with controllable cavity wall potential also includes: a first electrical contact portion disposed on the shield 20; a second electrical contact portion disposed within the working cavity 2, the second electrical contact portion being electrically connected to the output terminal of the active potential controller 30; the shield 20 being detachably disposed within the working cavity 2; after the shield 20 is installed in place, the first electrical contact portion and the second electrical contact portion are connected and conductive to realize the electrical connection between the shield 20 and the active potential controller 30; the RF magnetron sputtering device with controllable cavity wall potential also includes a disassembly and assembly safety protection unit, which includes at least one of the following: an insulated disassembly and assembly tool, matching the disassembly operation part of the shield 20, used to prevent the operator from directly contacting the conductor; a cavity door interlock switch, connected in series with the power enable terminal of the active potential controller 30, used to automatically cut off the power supply to the shield 20 when the cavity door is opened; and a residual charge discharge circuit, connected in parallel between the output terminal of the active potential controller 30 and the reference ground, used to quickly discharge the potential of the shield 20 to a safe value after power failure.

[0011] Furthermore, the RF magnetron sputtering device with controllable cavity wall potential also includes a magnetic field generating mechanism disposed within the sputtering source cavity 1. The magnetic field generating mechanism includes: a magnet 41 disposed above the target material 10; and a rotation drive assembly for driving the magnet 41 to perform circular motion to homogenize the magnetic field on the target surface. The RF magnetron sputtering device with controllable cavity wall potential also includes a symmetrical frame-type conductive structure disposed within the sputtering source cavity 1. The symmetrical frame-type conductive structure includes a circular top surface 51 and a cylindrical wall surface 52. The magnetic field generating mechanism is disposed within the cylindrical wall surface 52 in a circular shape. Within the space formed; the circular top surface 51 and the cylindrical wall surface 52 are both made of conductive material. The top of the cylindrical wall surface 52 is connected to the circular top surface 51, and the bottom of the cylindrical wall surface 52 is connected to the target material 10. A power terminal 53 is provided at the center of the circular top surface 51. The power terminal 53 passes through the top of the sputtering source cavity 1 and is connected to the radio frequency power supply located outside. The symmetrical frame conductive structure is used to uniformly diffuse radio frequency energy radially from the center of the circular top surface 51, and then uniformly conduct it axially to the central region of the target material 10 through the cylindrical wall surface 52.

[0012] Furthermore, the shell of the sputtering source cavity 1 is a double-layer composite structure, with the outer layer being a grounded electromagnetic shielding layer 1a and the inner layer being an insulating support layer 1b.

[0013] This application also provides a potential control method based on the above-mentioned radio frequency magnetron sputtering device with controllable cavity wall potential, comprising the following steps: providing a target material 10 connected to a radio frequency power supply and generating a periodically changing radio frequency electric field, each cycle of the radio frequency electric field including a positive half-cycle and a negative half-cycle; applying a positive potential to a shield 20 at least in each positive half-cycle through an active potential controller 30 to suppress the movement and attachment of positively charged particles to the shield 20 in an electrostatic repulsion manner; during sputtering, applying a constant positive potential to the shield 20 throughout the entire cycle of the radio frequency electric field, or making the potential of the shield 20 change periodically in sync with the radio frequency electric field, making the shield 20 present a positive potential in the positive half-cycle and a negative potential in the negative half-cycle, and controlling the absolute value of the negative potential to be insufficient to cause re-sputtering of particles attached to the shield 20.

[0014] Furthermore, the active potential controller 30 employs a composite control strategy, which includes the following steps: real-time acquisition of the RF voltage, RF current, and phase difference between voltage and current on the shield 20, while simultaneously acquiring process parameter disturbance signals, including changes in the power setpoint of the RF power supply, changes in gas pressure or gas flow rate within the working chamber 2; employing feedforward control to pre-calculate compensation amounts based on the acquired disturbance signals, and adjusting the capacitance value of the adjustable capacitor C and / or the output of the DC bias power supply in advance to suppress instantaneous overshoot of the shield 20 potential caused by sudden changes in process parameters; employing feedback control to compare the actual potential waveform of the shield 20 with the preset target potential waveform, calculate the deviation, and dynamically correct the adjustable capacitor C based on the deviation. The capacitance value of capacitor C and / or the output of the DC bias power supply; wherein, the feedback control is selected from at least one of the following algorithms: model predictive control algorithm, which establishes a dynamic model of the interaction between the shield 20 and the plasma, predicts the future system state in each control cycle, and solves the optimal control quantity that makes the predicted trajectory approximate the preset target potential waveform; sliding mode control algorithm, which designs a sliding surface with the potential error of the shield 20 and its derivative as state variables, and forces the system state to move along the sliding surface to enhance the robustness to plasma parameter perturbations and external disturbances; adaptive control algorithm, which identifies and estimates the equivalent parameters of the load formed by the shield 20 and the plasma in real time through online system identification, and automatically tunes the parameters of the controller according to the identification results to adapt to changes in process conditions.

[0015] This application provides a radio frequency magnetron sputtering device with controllable cavity wall potential, including a sputtering source cavity, a target material, a working cavity, a shield, and an active potential controller. The sputtering source cavity and the working cavity are sealed together, forming a process cavity. The target material is connected to a radio frequency power supply, which can output a periodically changing radio frequency electric field. Each cycle of the radio frequency electric field includes a positive half-cycle and a negative half-cycle. The shield is made of conductive material and is used to define the deposition area of ​​sputtered particles. The active potential controller is electrically connected to the shield and is used to apply a potential to the shield so that the shield can repel positively charged particles at least during the positive half-cycle, thereby inhibiting particle adhesion to the shield. The active potential controller addresses the particle contamination defects caused by grounding or floating potential of the cavity wall and shield in traditional equipment through potential regulation. It blocks the contamination chain of particle adhesion, bombardment, and peeling from the source, thereby significantly reducing particulate contaminants in the cavity and solving the problems of low coating yield caused by particle contamination in traditional radio frequency magnetron sputtering, meeting the cleanliness requirements of high-end semiconductor and precision optical coating.

[0016] This application also provides a potential control method based on the aforementioned RF magnetron sputtering device with controllable cavity wall potential. Through an active potential controller, precise potential regulation is implemented on the shielding device. At least during the positive half-cycle, a positive potential is applied to electrostatically repel positive ions, preventing particle adhesion and accumulation on the shielding device surface. Simultaneously, through a constant positive potential or a periodically varying potential mode synchronized with the RF, the negative potential during the negative half-cycle is strictly controlled below the particle re-sputtering threshold. This fundamentally prevents particle contamination caused by film deposition and peeling on the shielding device surface. Combined with structures and strategies such as insulation isolation, safe disassembly and assembly, and high-speed closed-loop control, it avoids potential leakage, gas breakdown, and arc damage, while ensuring a uniform and stable sputtering electric field. It effectively suppresses instantaneous potential overshoot and plasma disturbances under RF operating conditions. While achieving precise definition of the wafer sputtering area, it significantly improves the cleanliness and uniformity of the coating, solving the problems of particle contamination, film defects, and poor process stability caused by uncontrollable cavity wall / shielding potential in traditional RF magnetron sputtering devices. This significantly improves wafer coating yield and equipment operation safety. Attached Figure Description

[0017] Figure 1 A schematic diagram of the structure of a radio frequency magnetron sputtering device with controllable cavity wall potential provided in this application; Figure 2 for Figure 1 Enlarged view of the structure within the center circle; Figure 3 A circuit diagram of an active potential controller provided in this application. Detailed Implementation

[0018] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0019] This application provides a radio frequency magnetron sputtering device with controllable cavity wall potential, comprising: a sputtering source cavity 1 for mounting a target 10, the target 10 being connected to a radio frequency power supply, the radio frequency power supply being able to output a periodically changing radio frequency electric field, each cycle of the radio frequency electric field including a positive half-cycle and a negative half-cycle; a working cavity 2 connected to the sputtering source cavity 1, the working cavity 2 having a lifting stage for supporting a wafer, the target 10 facing the lifting stage; a shield 20 made of conductive material, arranged in a ring shape, disposed within the working cavity 2, below the target 10, and surrounding the sputtering surface of the target 10, for abutting against the wafer on the lifting stage when it is raised, thereby defining the deposition area of ​​sputtered particles; and an active potential controller 30 electrically connected to the shield 20, for applying a potential to the shield 20, such that the shield 20 can repel positively charged particles at least during the positive half-cycle, thereby suppressing particle adhesion on the shield 20.

[0020] For details, please refer to Figure 1 In the illustrated embodiment, the sputtering source cavity 1 is the mounting cavity for the target 10. The bottom of the sputtering source cavity 1 is open, and the target 10 is fixed to the bottom of the sputtering source cavity 1, forming a closed space between them that can accommodate the magnetic field generating mechanism and the symmetrical frame conductive structure. The target 10 is connected to an external radio frequency power supply through the symmetrical frame conductive structure.

[0021] Continue to refer to Figure 1 The top of the working chamber 2 is open and sealed to the sputtering source chamber 1. The working chamber 2 contains a platform (i.e., a lifting platform, which includes a stage and a lifting drive unit, both existing technologies and not described in detail here) capable of axial lifting movement, used to support and move the wafer. The sputtering surface of the target 10 is positioned directly opposite the lifting platform.

[0022] Continue to refer to Figure 1 The shield 20 is generally cylindrical and is located below the target 10 and surrounds the sputtering surface of the target 10. During operation, the lifting stage moves the wafer up to touch the shield 20, and the sputtering surface of the target 10 is exposed in the space formed by the shield 20 and the wafer. The shield 20 can effectively limit the sputtering range of particles and prevent the sputtered particles from contaminating the working cavity 2.

[0023] Continue to refer to Figure 1The active potential controller 30 is electrically connected to the shield 20, forming an independent shield potential control loop.

[0024] It should be explained that the RF power supply adopts a high-frequency AC power supply mode of 13.56MHz, and the output electric field has a complete cycle of approximately 73.9 nanoseconds. With the target potential as a reference, it can be divided into negative half-cycle and positive half-cycle. In the negative half-cycle, the target potential is negative relative to the plasma potential. Positive ions in the plasma are strongly accelerated and bombard the surface of the target 10 to achieve sputtering deposition, while secondary electrons are excited to maintain the plasma state. In the positive half-cycle, the target potential is positive relative to the plasma potential. High-speed electrons with masses much smaller than ions are rapidly attracted to the target surface, neutralizing the local positive charge accumulated in the negative half-cycle. This prevents the target 10 from "target poisoning" due to the inability to conduct away the charge, which would lead to sputtering termination. At the same time, it smooths out the uneven potential on the target surface to suppress the generation of destructive arcs.

[0025] In traditional equipment, the cavity wall and shielding components are mostly in a grounded or floating potential state. During the negative half-cycle, they are negatively potentialed relative to the plasma, which attracts positive ions to bombard the film layer already deposited on their surface, causing secondary sputtering of the film layer and forming contaminant particles. During the positive half-cycle, their potential passively fluctuates with the plasma potential and cannot stably repel positive ions. After the particles continue to adhere and accumulate, they are easy to fall off, which will further deteriorate the cleanliness of the cavity.

[0026] This application, by setting an active potential controller 30, can apply a stable control potential to the shield 20, forcing the shield 20 to maintain a clear and stable positive potential at least during the positive half-cycle of radio frequency, so as to continuously repel positive ions and positively charged contamination particle precursors in the plasma, thereby cutting off the contamination chain of film deposition, bombardment, and re-detachment from the source, and achieving the effect of preventing particle adhesion and secondary sputtering on the surface of the shield 20 in a simple and reliable way.

[0027] In one embodiment, the active potential controller 30 is configured to keep the shield 20 continuously at a positive potential. Specifically, the active potential controller 30 is used to apply a constant positive DC bias voltage to the shield 20, the value of which is set to be higher than the maximum fluctuation value of the plasma potential during the radio frequency discharge process, so as to always form a stable electrostatic barrier that repels positive ions on the surface of the shield 20 throughout the entire radio frequency cycle, including the negative half-cycle.

[0028] It should be added that the minimum value of the positive DC bias voltage must be higher than the maximum floating potential that the plasma can reach in the positive half-cycle. Under normal operating conditions, this floating potential should not exceed +20V~+30V. At the same time, it is necessary to ensure that the potential of the shield 20 remains positive even under the harsh operating conditions where the plasma potential is the lowest in the negative half-cycle. If the bias voltage value is set too low, it will easily lose its repulsive effect when the plasma fluctuates. If it is set too high, it will attract a large number of electrons, causing unnecessary energy loss and component heating. In practical applications, the positive DC bias voltage can be set in the range of +30V~+100V.

[0029] For example, +30V can be selected. The constant +30V positive DC bias voltage, adapted to the 13.56MHz RF operating conditions, is output from the DC bias power supply in the active potential controller 30, which can stably meet the design requirements of the shield 20 for repelling positive ions throughout the entire cycle.

[0030] In one specific embodiment, when the active potential controller 30 is configured to keep the shield 20 continuously at a positive potential, the active potential controller 30 includes: a DC bias power supply for continuously applying a constant positive DC voltage to the shield 20 so that the shield 20 is always at a positive potential throughout the entire cycle of the radio frequency electric field; and a filter network connected between the DC bias power supply and the shield 20 for preventing radio frequency energy from entering the DC bias power supply.

[0031] Specifically, the output terminal of the DC bias power supply is connected to the input terminal of the filter network, and the output terminal of the filter network is electrically connected to the shield 20. The two are connected in series to form a stable DC power supply path.

[0032] The DC bias power supply serves as the core power supply unit, continuously outputting a constant positive DC voltage to the shield 20 to ensure that the shield 20 maintains a stable positive potential throughout the entire cycle of the 13.56MHz RF electric field. The filter network integrates at least one RF choke, which presents a high impedance of not less than 1000Ω to RF signals in the operating frequency band, effectively blocking the reverse inversion of RF energy into the DC bias power supply. At the same time, it presents a low impedance of less than 1Ω to DC signals, ensuring that it does not hinder the normal transmission of the DC bias voltage.

[0033] To further optimize the filtering effect, one or two bypass capacitors can be added to the filter network to form an LC filter or a π-type filter in conjunction with the RF choke. This can deeply filter out residual RF ripple in the circuit and avoid RF interference causing DC bias output fluctuations, thereby providing a clean, stable, and constant positive DC bias for the shield 20 and ensuring the continuous reliability of the electrostatic barrier on the surface of the shield 20.

[0034] In another embodiment, the active potential controller 30 is configured to cause the potential of the shield 20 to change periodically in sync with the radio frequency power supply. Specifically, during the positive half-cycle, the shield 20 presents a positive potential; during the negative half-cycle, the shield 20 presents a negative potential, and the absolute value of the negative potential is configured to be less than a threshold that can attract positive ions to bombard particles attached to the shield 20.

[0035] Setting the potential of the shield 20 to change periodically in sync with the RF power supply has multiple advantages over the above-mentioned continuous positive potential scheme. On the one hand, it can make the film layer attached to the surface of the shield 20 denser and have stronger adhesion. On the other hand, it can reduce electrical interference to the main RF field. In addition, it can be adapted to a wider process window.

[0036] It is easy to understand that during the negative half-cycle, the mild ion bombardment generated when the shield 20 is at a weak negative potential will form an ion-assisted deposition effect, which can reduce the internal stress of the film, improve adhesion, and reduce particulate contamination from the source. At the same time, the instantaneous potential difference between the shield 20 and the target 10 remains constant, which can reduce the RF current shunting caused by parasitic capacitance coupling and improve the utilization efficiency of RF energy. The dynamically adjustable potential matching mode can also adapt to the plasma potential changes under different target materials 10, gas pressure and RF power, expanding the process applicability range of the equipment.

[0037] In this embodiment, the positive half-cycle shielding element 20 exhibits a positive potential to effectively repel positive ions, while the negative half-cycle shielding element 20 exhibits a weak negative potential. The absolute value of this negative potential is strictly configured to be less than the critical threshold for attracting positive ions to bombard particles attached to the surface of the shielding element (typically, the negative potential is controlled in the range of -20V to -50V). This voltage cannot accelerate positive ions to the energy sufficient to bombard atoms on the surface of the shielding element 20, but can only attract low-energy deposition particle precursors to achieve gentle impact. This avoids the generation of contamination particles from secondary sputtering of the film layer, and optimizes the film layer density and adhesion through ion-assisted deposition, avoiding the problem of loose and easily peeled film layers under continuous positive potential.

[0038] In one specific embodiment, when the active potential controller 30 is configured to cause the potential of the shield 20 to change periodically in sync with the RF power supply, the active potential controller 30 includes: an adjustable impedance matching network connected between the shield 20 and a reference ground, including a fixed inductor L1 and an adjustable capacitor C, for adjusting the RF impedance at the shield 20 so that the potential of the shield 20 changes periodically in sync with the RF power supply; a DC bias power supply connected to the shield 20 through an isolation inductor L2, for providing a programmable DC bias voltage to the shield 20; a VI sensor connected between the shield 20 and the adjustable impedance matching network, for measuring the RF current flowing through the shield 20, the voltage to ground, and their phase difference in real time; and a controller connected to the VI sensor, the adjustable capacitor C, and the DC bias power supply, for controlling the capacitance value of the adjustable capacitor C and / or the output of the DC bias power supply in a closed loop according to the measurement results of the VI sensor, thereby dynamically maintaining the preset potential waveform of the shield 20.

[0039] For details, please refer to Figure 3 An adjustable impedance matching network, consisting of a fixed inductor L1 and an adjustable capacitor C, is connected between the shield 20 and the reference ground. This network precisely adjusts the RF impedance of the shield 20, ensuring its potential changes synchronously with the RF power supply cycle. A DC bias power supply is connected to the shield 20 via an isolation inductor L2, providing a programmable DC bias voltage. A VI sensor is connected in series between the shield 20 and the adjustable impedance matching network, enabling real-time detection of the RF current flowing through the shield 20, its voltage to ground, and the phase difference between the two.

[0040] Continue to refer to Figure 3 The controller establishes signal connections with the VI sensor, the adjustable capacitor C, and the DC bias power supply. Based on the real-time measurement parameters returned by the VI sensor, it can adjust the capacitance value of the adjustable capacitor C and the output of the DC bias power supply in a closed loop to complete impedance matching and bias calibration in a coordinated manner. It dynamically locks and maintains the preset periodic potential waveform of the shield 20, so that the shield 20 can stably output a positive potential in the positive half-cycle of RF and a weak negative potential in the negative half-cycle. It can accurately achieve synchronous adaptation of potential and RF operating conditions, and ensure that the shield 20 can stably achieve the dual effects of preventing particle adhesion and densifying the film.

[0041] The radio frequency magnetron sputtering device with controllable cavity wall potential provided in this application provides a stable mounting carrier for the target 10 by setting up a sputtering source cavity 1. The target 10 is connected to a radio frequency power supply, which outputs a periodic radio frequency electric field containing positive and negative half-cycles. The negative half-cycle completes the target sputtering operation, while the positive half-cycle neutralizes the target surface charge accumulation and reduces the target potential fluctuation, thus solving the problem of target surface particle sputtering caused by destructive arcs. The working cavity 2 is connected to the sputtering source cavity 1. Inside the working cavity 2, the lifting stage can achieve precise wafer mounting and alignment. The component 20 is located below the target material 10 and defines the deposition area of ​​sputtered particles, which can prevent particle diffusion and contamination of the inner wall of the working cavity 2. The active potential controller 30 solves the particle contamination defects caused by the grounding or floating potential of the cavity wall and the shield 20 in traditional equipment through potential regulation. It blocks the contamination chain of particle adhesion, bombardment and peeling from the source, thereby greatly reducing the particulate contaminants in the cavity and solving the problems of low coating yield caused by particle contamination in traditional radio frequency magnetron sputtering, meeting the cleanliness requirements of high-end semiconductor and precision optical coating.

[0042] Optionally, the active potential controller 30 also includes an ion energy analyzer, which is located near the shield 20 and is used to measure the positive ion energy distribution and ion flux density bombarding the surface of the shield 20 in real time. The controller is connected to the ion energy analyzer and is configured to reduce the absolute value of the negative bias voltage of the shield 20 or increase the positive bias voltage of the shield 20 when the ion energy analyzer detects that the ion energy on the surface of the shield 20 exceeds a preset critical sputtering threshold.

[0043] The ion energy analyzer can be a retardation field energy analyzer (RFEA). This analyzer is arranged near the shield 20 or installed at the corresponding position on the inner wall of the cavity. It can directly measure the positive ion energy distribution and ion flux density bombarding the surface of the shield 20 in real time, accurately obtain the actual state of positive ion bombardment of the shield 20, and provide the most direct and accurate criterion for the control of the shield potential. With the help of the controller, the bias voltage of the shield 20 can be adjusted as needed to ensure that the ion energy is always below the critical sputtering threshold, avoid secondary sputtering of the film layer on the surface of the shield 20 due to high-energy ion bombardment, and further enhance the source suppression effect of particulate contamination.

[0044] Optionally, the active potential controller 30 also includes a plasma potential probe, which is located in the working chamber 2 and is used to measure the plasma potential in real time. The controller is connected to the plasma potential probe and is configured to dynamically adjust the preset potential waveform of the shield 20 according to the difference between the plasma potential and the reference ground potential, so that the absolute value of the negative potential of the shield 20 in the negative half-cycle is always less than the difference, thereby avoiding attracting high-energy positive ion bombardment.

[0045] The plasma potential probe can be a radio frequency compensated Langmuir probe or an emission probe. The probe is installed inside the working cavity 2 and can accurately detect the plasma potential and electron temperature in the cavity in real time, providing a core reference for determining the critical negative potential for the control of the shield potential.

[0046] The controller is connected to the plasma potential probe and can dynamically adjust the preset potential waveform of the shield 20 based on the difference between the measured plasma potential and the reference ground potential. This ensures that the absolute value of the negative potential of the shield 20 during the negative half-cycle is always less than the difference, thus avoiding the attraction of high-energy positive ions to bombard the shield. At the same time, the shield potential control is upgraded from a fixed preset voltage value to a relative difference control with the plasma potential, which greatly improves the device's adaptability to changes in process conditions.

[0047] Optionally, the sampling rate of the VI sensor is not less than 50MHz, used to acquire the instantaneous waveforms of the RF voltage and current on the shield 20. The controller is configured to calculate the actual potential peaks of the shield 20 in the positive and negative half-cycles of each RF cycle based on the instantaneous waveforms, and compare them with the preset target waveform to correct the capacitance value of the adjustable capacitor C and / or the output of the DC bias power supply.

[0048] The reason for setting the sampling rate of the VI sensor to no less than 50MHz is that this sampling rate is much higher than the 13.56MHz RF operating frequency, which can fully capture the instantaneous waveform details of the device potential within the RF cycle, rather than just obtaining the root mean square value.

[0049] At this time, the VI sensor can collect the instantaneous waveforms of the RF voltage and current on the shield 20 in real time. The controller accurately calculates the actual potential peaks of the shield 20 in the positive and negative half-cycles of each RF cycle based on the collected instantaneous waveforms. After comparing them with the preset target waveform, the controller corrects the capacitance value of the adjustable capacitor C or the output of the DC bias power supply. This can effectively identify microsecond-level potential spikes and transient overshoots, avoid the problem of average voltage meeting the standard but instantaneous voltage exceeding the limit, and ensure that the shield potential accurately matches the preset target value throughout the entire RF cycle.

[0050] Optionally, the active potential controller 30 also includes an arc detection module, which is connected to the VI sensor to monitor the rate of change of voltage and / or current spikes on the shield 20 to identify arc events. The controller is connected to the arc detection module and is configured to forcibly switch the potential of the shield 20 to a preset positive safe potential within microseconds when an arc event is detected, and restore the preset target waveform after the arc is extinguished.

[0051] The arc detection module is a fast protection module integrated within the active potential controller 30 for rapid identification of arc events. This module connects to the VI sensor and achieves microsecond-level arc identification by real-time monitoring of the voltage surge rate and current spikes on the shield 20. Maintaining signal communication with the controller, the arc detection module can accurately capture the instantaneous and drastic fluctuations in the shield's potential, compensating for the lag in response of conventional closed-loop control.

[0052] When an electric arc is detected, the arc detection module can work with the controller to forcibly switch the potential of the shield 20 to a preset positive safe potential within microseconds, blocking the arc from discharging through the shield 20. After the arc is extinguished, the normal preset target potential waveform is restored. This reduces the time of the shield potential runaway caused by the arc from milliseconds to microseconds, effectively protecting the integrity of the film layer on the surface of the shield 20 and preventing the arc from causing film layer damage and particulate contamination.

[0053] Optionally, the VI sensor is configured to extract harmonic components of the operating frequency of the RF power supply, the harmonic components including at least the second harmonic and / or the third harmonic, and the controller is configured to analyze the amplitude and phase changes of the harmonic components to diagnose the microstate of the plasma and provide an early warning that the negative potential of the shield 20 may exceed a critical threshold when abnormal changes occur in the harmonic components.

[0054] It should be explained that the harmonic components are generated by the nonlinear characteristics of plasma and are frequency harmonics of the 13.56MHz radio frequency fundamental wave. They mainly include the 27.12MHz second harmonic and the 40.68MHz third harmonic. These harmonics carry sensitive information about the plasma microstate, such as electron energy distribution and ion density, and can reflect changes in plasma state more sensitively than the fundamental wave parameters.

[0055] The VI sensor is configured to extract these harmonic components, thereby accurately capturing the core characteristic signals reflecting the plasma state and providing crucial data for plasma state diagnosis. The controller and VI sensor work together to analyze the amplitude and phase changes of the harmonic components in real time. Leveraging the high sensitivity of harmonics, abnormal fluctuations in the plasma's microstate are identified in advance, providing early warning of potential exceedances of the critical threshold for the negative potential of the shielding element 20, thus offering predictive support for precise control of the shielding element potential.

[0056] Optionally, the active potential controller 30 also includes a dual-channel redundant measurement unit, which includes two independently configured VI sensors. The two VI sensors are respectively arranged at different positions or different electrical connection points of the shield 20. The controller is connected to the two VI sensors respectively and is configured to cross-verify the two measurement data. When the deviation between the two data exceeds a preset threshold, it is judged as a sensor failure and the potential of the shield 20 is automatically switched to a conservative safety mode, which is a continuous positive potential.

[0057] The dual-channel redundant measurement unit is a redundant monitoring component in the active potential controller 30 used to improve measurement reliability and system safety. It consists of two independent VI sensors, which are respectively arranged at both ends of the shield 20 or at different electrical connection points, and simultaneously measure the electrical parameters of the shield 20. Both sensors establish independent signal connections with the controller. The controller cross-verifies the two measurement data in real time. When the deviation between the two data exceeds a preset threshold, it can be determined that the sensor has drifted or failed, and then automatically switches the potential of the shield 20 to a conservative safety mode with a continuous positive potential.

[0058] The conservative safety mode is a fallback protection mode automatically triggered by the controller after the dual-channel redundant measurement unit determines a sensor failure. In this mode, the active potential controller 30 stops the dynamic control logic of the periodic synchronous electromotive force change and forcibly switches the potential of the shield 20 to a continuous constant positive potential. It forms a full-cycle electrostatic barrier on the surface of the shield 20 with the most stable and reliable DC positive bias voltage, which repels positive ions in the plasma throughout the process. This prevents the shield 20 from potential runaway due to sensor failure, attracting positive ions to bombard the film and causing secondary sputtering and particulate contamination. It ensures that the equipment can maintain the core anti-contamination protection effect under abnormal operating conditions, and guarantees the basic safety and cleanliness of the coating process.

[0059] The dual-channel redundant measurement unit effectively avoids control failure caused by single-point sensor failure through dual-channel independent measurement and cross-verification, greatly improving the robustness and safety of system operation, and fundamentally eliminating the situation of uncontrolled device potential and particulate contamination caused by secondary sputtering of film due to measurement abnormalities.

[0060] Optionally, the adjustable capacitor C is a piezoelectric ceramic driven vacuum variable capacitor with an adjustment accuracy of ±0.1pF.

[0061] When the adjustable capacitor C is a piezoelectric ceramic driven vacuum variable capacitor, the ultra-high adjustment accuracy of ±0.1pF can shorten the response time of the impedance matching network to 50 microseconds, so as to finely adjust the RF impedance at the shield 20 and ensure that the shield potential is precisely synchronized with the RF power supply cycle.

[0062] Optionally, the DC bias power supply is a programmable DC power supply with a resolution of 16 bits or higher.

[0063] The DC bias power supply uses a programmable DC power supply with a resolution of 16 bits or higher, which can achieve millivolt-level output voltage resolution and provide a precise and controllable DC bias voltage for the shield 20, meeting the needs of fine adjustment of the shield potential.

[0064] Optionally, the controller is a field-programmable gate array (FPGA) with a control cycle of no more than 1 microsecond.

[0065] The controller uses a field-programmable gate array (FPGA) and relies on high-speed parallel processing capabilities to shorten the control cycle to sub-microsecond levels. This enables rapid processing of measurement data and output of control commands, achieving high-speed closed-loop control of the adjustable capacitor and DC bias power supply, and ensuring dynamic stability and accurate output of the preset potential waveform of the shielding element 20.

[0066] When simultaneously employing a piezoelectric ceramic driving vacuum variable capacitor C with a ±0.1pF adjustment accuracy, a programmable DC bias power supply with a resolution of 16 bits or higher, and an FPGA controller with a control cycle of no more than 1μs, the active potential controller 30 can form a high-speed, high-precision, and high-dynamic-response closed-loop potential control system. Relying on the sub-microsecond parallel processing speed of the FPGA, it acquires and processes high-frequency waveform data from the VI sensor in real time. On one hand, through the ultra-fast and ultra-fine capacitance adjustment of the piezoelectric ceramic capacitor, it quickly and accurately matches the RF impedance, compressing the impedance adjustment response to the microsecond level, ensuring that the shielding potential is strictly synchronized with the 13.56MHz RF cycle, avoiding phase shift and potential fluctuations. On the other hand, relying on the high-resolution DC power supply to achieve millivolt-level potential output, it precisely controls the positive potential amplitude of the shielding in the positive half-cycle and the negative potential amplitude in the negative half-cycle, ensuring that the negative potential is always below the particle re-sputtering threshold. The three components work together to suppress instantaneous potential overshoot caused by sudden changes in process parameters, and provide microsecond-level rapid protection when an arc occurs. They continuously and stably clamp the potential of the shielding component onto the target waveform, fundamentally eliminating particle adhesion, film re-sputtering, and particulate contamination, and significantly improving the stability, controllability, cleanliness, and uniformity of the sputtering process and wafer coating.

[0067] Optionally, an insulating structure is provided between the shield 20 and the sputtering source cavity 1, and between the shield 20 and the working cavity 2, to prevent the potential on the shield 20 from leaking to other grounded or floating components.

[0068] To prevent the control potential on the shield 20 from leaking to grounded or floating components such as sputtering source cavity 1 and working cavity 2, and to ensure that the shield potential is stable and controllable and does not interfere with the RF field distribution and active potential control accuracy within the cavity, an insulating structure needs to be set between the shield 20 and the surrounding cavity components.

[0069] The insulation structure can adopt any configuration of ceramic gaskets, ceramic coatings or polyetheretherketone (PEEK) insulation components, which has both good insulation performance and structural stability.

[0070] In one specific embodiment, refer to Figure 1 and Figure 2A first insulating block 61 is provided between the shield 20 and the sputtering source cavity 1, and a second insulating block 62 is provided between the shield 20 and the working cavity 2. The first insulating block 61 is made of insulating material and is located at the connection between the shield 20 and the sputtering source cavity 1; the second insulating block 62 is also made of insulating material and is located at the connection between the shield 20 and the working cavity 2. The two blocks provide electrical isolation between the shield 20 and the sputtering source cavity 1 and between the shield 20 and the working cavity 2, respectively, which can physically block the potential of the shield 20 from being conducted outward, ensuring that the active potential controller 30 can accurately and effectively regulate the potential of the shield 20.

[0071] Optionally, the shield 20 and the target 10 are electrically isolated by a physical gap, the distance of which is configured to be greater than the Paschen breakdown distance corresponding to the maximum potential difference between the shield 20 and the target 10, so as to avoid gas breakdown.

[0072] It is easy to understand that the shield 20 and the target 10 also need to be electrically isolated to prevent the gas in the cavity from breaking down due to the potential difference between the two, and to prevent the discharge phenomenon from interfering with the normal sputtering process, damaging the stability of the shield potential control and the electric field distribution in the cavity.

[0073] For details, please refer to Figure 2 In the illustrated embodiment, electrical isolation is achieved by creating a physical vacuum gap between the shield 20 and the target 10 (a vacuum is created in the cavity during sputtering using a negative pressure device). The distance of the physical gap is controlled between 1mm and 5mm, and the gap distance is greater than the Paschen breakdown distance corresponding to the maximum potential difference between the shield 20 and the target 10. In this way, the gas breakdown path can be physically blocked, achieving stable and reliable electrical isolation between the two.

[0074] Furthermore, the upper surface of the shield 20 is higher than the sputtering surface of the target 10, so that the gap between the two is located within the line-of-sight deposition shadow area of ​​the sputtered particle stream of the target 10, thereby avoiding electrical short circuits caused by the deposition of conductive films within the physical gap.

[0075] For details, please refer to Figure 2 In the illustrated embodiment, the shield 20 is disposed around the bottom of the target 10 and surrounds the sputtering surface of the target 10. Since the upper surface of the shield 20 is higher than the sputtering surface of the target 10 facing the wafer, and part of the target 20 is inserted into the shield 20, an annular physical gap is formed between the two, oriented horizontally or obliquely upward. Furthermore, since the target particles in magnetron sputtering fall vertically in a straight line or fly obliquely downward, they cannot bend into this gap. Therefore, the gap between the shield 20 and the target 10 is entirely within the geometric line-of-sight deposition shadow area of ​​the sputtered particle stream, fundamentally preventing the deposition of conductive films within the gap.

[0076] In addition, the shield 20 is a consumable component that can be disassembled for cleaning or replacement periodically. Therefore, the insulation performance of the gap can be continuously guaranteed during the service life. Combined with the rapid active protection mechanism of the arc detection module, even if a micro-arc occurs, the arc energy can be suppressed in time to avoid permanent damage, thereby ensuring the stable and reliable electrical isolation between the shield 20 and the target material 10 in all aspects.

[0077] In practice, to ensure a clean coating environment, the equipment needs to be shut down periodically or as needed, and internal components cleaned. The shielding element 20 is one of the key components requiring cleaning. To facilitate assembly and disassembly while ensuring reliable electrical connection, the RF magnetron sputtering device with controllable cavity wall potential includes: a first electrical contact on the shielding element 20; a second electrical contact inside the working chamber 2, electrically connected to the output terminal of the active potential controller 30; the shielding element 20 is detachably mounted inside the working chamber 2; after the shielding element 20 is installed in place, the first and second electrical contacts connect and conduct, thus achieving electrical connection between the shielding element 20 and the active potential controller 30.

[0078] Specifically, the shield 20 can be detachably installed in the working cavity 2 by means of screwing, plugging, or other methods. The first electrical contact and the second electrical contact are also made of conductive material and are arranged in a way that facilitates mutual contact and conduction.

[0079] In one embodiment, the shield 20 is made of conductive material and has a mounting flange 21 (used as a first electrical contact) on its outer periphery; the inner wall of the working cavity 2 is provided with a bearing step 22 opposite to the mounting flange 21; the RF magnetron sputtering device with controllable cavity wall potential also includes multiple conductive fasteners (used as second electrical contacts), which can pass through the mounting flange 21 and be fixed to the bearing step 22, thereby achieving mechanical locking between the shield 20 and the working cavity 2 to resist the jacking force when the lifting platform rises; the output wire of the active potential controller 30 is fixed to the bearing step 22, and after the conductive fastener is installed in place, it can be connected to the output wire, thereby achieving electrical connection between the shield 20 and the active potential controller 30.

[0080] For details, please refer to Figure 2 In the illustrated embodiment, the shield 20 is generally hollow cylindrical and is disposed around the sputtering surface of the target 10. An outwardly extending annular mounting flange 21 is provided on the outer peripheral surface of the upper part of the shield 20.

[0081] Continue to refer to Figure 2 The inner wall of the working chamber 2 is provided with an annular bearing step 22 that matches the outer dimensions of the mounting flange 21, and the two can be aligned and fitted together.

[0082] Continue to refer to Figure 2The mounting flange 21 and the bearing step 22 are provided with multiple sets of corresponding pre-drilled through holes and threaded holes for inserting conductive fasteners. The conductive fasteners can be made of titanium alloy or stainless steel hexagon head screws. The conductive fasteners can pass through the pre-drilled through holes on the mounting flange 21 and be screwed into the corresponding threaded holes on the bearing step 22, thereby firmly pressing the cover 20 onto the bearing step 22 through the screw tightening force, effectively resisting the upward thrust when the lifting platform rises, and achieving stable mechanical fixation.

[0083] Meanwhile, the output wire of the active potential controller 30 is embedded in the bearing step 22, and its terminal is located in the threaded hole. After the conductive fastener is installed in place, it can make close contact with the terminal. In this way, a reliable electrical connection between the shield 20 and the active potential controller 30 can be directly completed with the help of the conductive fastener.

[0084] Optionally, a wave spring washer or a disc spring washer can be installed between the conductive fastener and the flange face. In this way, the spring washer / disc spring washer can continuously provide preload in a high-temperature vacuum environment, which can effectively prevent the screw from loosening due to thermal cycling.

[0085] In another embodiment, the bottom surface of the mounting flange 21 of the cover 20 is fitted with multiple sets of conductive springs (serving as first electrical contacts), and conductive contacts (serving as second electrical contacts) are correspondingly arranged on the bearing step 22 of the working cavity 2. The output wire of the active potential controller 30 is connected to the conductive contacts. During assembly, the mounting flange 21 is aligned and placed on the bearing step 22, and the conductive springs and conductive contacts are elastically pressed together to achieve electrical connection. Then, the cover 20 is mechanically fixed by ordinary insulating fasteners. Thus, during disassembly and assembly, only the fasteners need to be removed to remove the cover 20, and the elastic contact conductive structure does not require wire disassembly and assembly.

[0086] In another embodiment, a male conductive plug (used as a first electrical contact) is provided on the side of the mounting flange 21 of the cover 20, and a female conductive socket (used as a second electrical contact) is pre-embedded at the corresponding position of the bearing step 22 of the working cavity 2. The socket is connected to the output wire of the active potential controller 30. When assembling the cover 20, it is placed downwards and aligned. The male plug is inserted into the female socket to achieve electrical connection. Then, a rotating snap fastener is used to complete the mechanical locking. There are no problems of wire twisting or tangling during the disassembly and assembly process. It can conduct electricity immediately upon insertion and disconnect power immediately upon removal. It can effectively ensure the stability of the power connection while facilitating disassembly and assembly.

[0087] This application does not limit the specific power connection method of the shield 20.

[0088] Furthermore, the RF magnetron sputtering device with controllable cavity wall potential also includes a disassembly and assembly safety protection unit, which includes at least one of the following: an insulated disassembly and assembly tool, which is matched with the disassembly operation part of the shield 20, to prevent the operator from directly contacting the conductor; a cavity door interlock switch, which is connected in series with the power enable terminal of the active potential controller 30, to automatically cut off the power supply to the shield 20 when the cavity door is opened; and a residual charge discharge circuit, which is connected in parallel between the output terminal of the active potential controller 30 and the reference ground, to quickly discharge the potential of the shield 20 to a safe value after power failure.

[0089] For example, the insulated assembly / disassembly tool is a specialized tool adapted to the operating parts of conductive fasteners. Both its grip and shaft are covered with a high-voltage resistant insulating layer. It is provided with the equipment and is for the exclusive use of the operator. When disassembling or assembling the shield 20, this tool can only be used to operate the conductive fasteners, preventing the operator's hands from directly contacting live parts and eliminating the risk of electric shock from an operational perspective.

[0090] The cavity door interlock switch is a micro switch installed at the cavity door of the working cavity 2. This switch is connected in series with the power enable terminal of the active potential controller 30. When the cavity door is opened, the micro switch is immediately disconnected, and the power supply circuit of the shield 20 is forcibly cut off at the hardware level, so that the shield 20 automatically returns to zero potential, ensuring that the shield 20 has no risk of being electrified during disassembly and assembly from the hardware level.

[0091] It should be noted that in this application, "cavity" refers to a component that needs to be opened and closed during assembly and disassembly. Specifically... Figure 1 In the middle, the cavity door can be the sputtering source cavity 1 or a related connecting component used to drive the sputtering source cavity 1 to perform a flipping action. The cavity door interlock switch is used to forcibly cut off the power supply circuit of the shield 20 when the sputtering source cavity 1 is detected to be flipped relative to the working cavity 2.

[0092] The residual charge discharge circuit uses a discharge resistor as its core component and is connected in parallel between the output terminal of the active potential controller 30 and the reference ground. It can quickly discharge the residual charge on the shield 20 after the equipment is powered off or the power supply is cut off, and rapidly reduce the potential of the shield to below the safe voltage, thus completely eliminating the risk of electric shock caused by residual charge.

[0093] The insulated disassembly and assembly tools, the cavity door interlock switch, and the residual charge discharge circuit work together to form a complete disassembly and assembly safety protection system, which can comprehensively ensure the operational safety of the disassembly and assembly process of the shield 20.

[0094] The radio frequency magnetron sputtering device with controllable cavity wall potential provided in this application also includes a magnetic field generating mechanism disposed in the sputtering source cavity 1. The magnetic field generating mechanism includes: a magnet 41 disposed above the target material 10; a rotation drive assembly, which includes a driver 42 and an annular slide rail 43. The driver 42 is used to drive the magnet 41 to make circular motion along the annular slide rail 43 to homogenize the magnetic field on the target surface.

[0095] For details, please refer to Figure 1 In the illustrated embodiment, the magnetic field generating mechanism is disposed inside the enclosed cavity formed by the sputtering source cavity 1 and the target material 10. Magnet 41 is arranged above the target material 10 to form a working magnetic field for confining plasma in the target surface area. The annular slide rail 43 is a closed annular track structure, coaxially disposed above the target material 10, and magnet 41 is slidably mounted on the annular slide rail 43 via a slider. The driver 42 is a geared motor, capable of driving magnet 41 to move in a circular motion along the annular slide rail 43, thereby dynamically homogenizing the magnetic field distribution on the surface of the target material 10, avoiding sputtering deviations caused by uneven local magnetic field strength, and improving the sputtering uniformity of the target material 20 and the overall consistency of thin film deposition.

[0096] Since the presence of the magnetic field generating mechanism occupies a large amount of internal space of the sputtering source cavity 1, in order to facilitate external power connection while ensuring the uniformity of power supply to the target surface, in one embodiment, the RF magnetron sputtering device with controllable cavity wall potential provided in this application further includes a symmetrical frame conductive structure disposed within the sputtering source cavity 1. The symmetrical frame conductive structure includes a circular top surface 51 and a cylindrical wall surface 52 arranged coaxially. The magnetic field generating mechanism is disposed within the space enclosed by the cylindrical wall surface 52. Both the circular top surface 51 and the cylindrical wall surface 52 are made of conductive material. The top of the cylindrical wall surface 52 is connected to the circular top surface 51, and the bottom of the cylindrical wall surface 52 is connected to the target material 10. A power terminal 53 is provided at the center of the circular top surface 51. The power terminal 53 passes through the top of the sputtering source cavity 1 and is connected to an external RF power supply. The symmetrical frame conductive structure is used to uniformly diffuse RF energy radially from the center of the circular top surface 51 and then uniformly conduct it axially through the cylindrical wall surface 52 to the central region of the target material 10.

[0097] For details, please refer to Figure 1 In the illustrated embodiment, a symmetrical frame-type conductive structure is arranged inside the enclosed cavity formed by the sputtering source cavity 1 and the target material 10. The circular top surface 51 and the cylindrical wall surface 52 are conductive components arranged coaxially. The circular top surface 51 is in the shape of a horizontal circular plate and is connected to the top of the cylindrical wall surface 52. The cylindrical wall surface 52 is vertically surrounded below the circular top surface 51 and its bottom is connected to the target material 10.

[0098] Continue to refer to Figure 1 The magnetic field generating mechanism is located in the internal space enclosed by the circular top surface 51, the cylindrical wall surface 52, and the target material 10. To facilitate the fixed installation of the magnetic field generating mechanism, the symmetrical frame conductive structure is also equipped with a mounting plate made of insulating material. The annular slide rail 43 is fixed to the bottom surface of the mounting plate facing the target material 10. The driver 42 is located on the top surface of the mounting plate, and the output shaft of the driver 42 passes through the mounting plate and is connected to the magnet 41.

[0099] Continue to refer to Figure 1A power terminal 53 is provided at the center of the circular top surface 51. The power terminal 53 passes upward through the top of the sputtering source cavity 1 and is connected to an external radio frequency power supply. This configuration allows radio frequency energy to be input from the central power terminal 53, diffused radially uniformly through the circular top surface 51, and then axially uniformly conducted to the central region of the target material 10 through the cylindrical wall surface 52. This not only reasonably avoids the internal space occupied by the magnetic field generating mechanism, but also achieves uniformity of power supply to the target surface and convenience of external power connection.

[0100] Optionally, the shell of the sputtering source cavity 1 is a double-layer composite structure, with the outer layer being a grounded electromagnetic shielding layer 1a and the inner layer being an insulating support layer 1b.

[0101] For details, please refer to Figure 2 In the illustrated embodiment, the outer shell of the sputtering source cavity 1 is an electromagnetic shielding layer 1a, which is made of thin metal and serves as the outer contour of the cavity and is grounded. The inner layer of the sputtering source cavity 1 is an insulating support layer 1b, which is made of insulating material and is tightly fitted to the inner side of the electromagnetic shielding layer 1a. The two work together to form a complete cavity wall.

[0102] More specifically, the electromagnetic shielding layer 1a is made of thin metal material, commonly aluminum, stainless steel or copper alloy, with a thickness typically controlled between 1mm and 5mm. This ensures both the rigidity of the cavity structure and the electromagnetic shielding effectiveness, without excessively increasing the cavity's weight. In terms of size, it completely covers the outer contour of the sputtering source cavity 1, forming a continuous, closed conductive shielding shell that is reliably grounded.

[0103] The insulating support layer 1b is made of insulating materials such as engineering ceramics, polyether ether ketone (PEEK) or high-temperature resistant engineering plastics. Its shape matches the inner wall of the electromagnetic shielding layer 1a. Its thickness is generally 2mm to 20mm. It fits tightly to the inner side of the electromagnetic shielding layer 1a in terms of size. The whole is continuous without any breaks. It not only provides stable structural support for the internal charged components, but also forms a sufficient insulating gap between the shielding layer and the internal charged components to meet the withstand voltage and electrical isolation requirements under radio frequency conditions.

[0104] The electromagnetic shielding layer 1a achieves radio frequency electromagnetic shielding through grounding, which can prevent the electromagnetic field inside the cavity from leaking outward and interfering with external equipment. The insulating support layer 1b provides reliable electrical isolation between the internal charged components and the outer shielding layer, which can prevent potential leakage and short circuits. At the same time, it provides structural support for the components inside the cavity, thus ensuring electrical insulation and structural stability inside the cavity while achieving electromagnetic protection.

[0105] This application also provides a potential control method, implemented based on the above-mentioned radio frequency magnetron sputtering device with controllable cavity wall potential, which includes the following steps: A target 10 is provided to be connected to an RF power supply and generates a periodically changing RF electric field, each cycle of which includes a positive half-cycle and a negative half-cycle. By means of active potential controller 30, a positive potential is applied to shield 20 at least in each positive half cycle to suppress the movement and attachment of positively charged particles to shield 20 in an electrostatic repulsion manner. During the sputtering process, a constant positive potential is applied to the shield 20 throughout the entire cycle of the radio frequency electric field, or the potential of the shield 20 is made to change periodically in sync with the radio frequency electric field, so that the shield 20 presents a positive potential in the positive half-cycle and a negative potential in the negative half-cycle, and the absolute value of the negative potential is controlled to be insufficient to cause re-sputtering of particles attached to the shield 20.

[0106] In one specific embodiment, the device is in standby mode. First, the cavity door interlock switch is triggered to turn on the power supply, and the radio frequency power supply is started. The radio frequency energy is uniformly conducted to the target material 10 through the symmetrical frame conductive structure. At the same time, the magnetic field generating mechanism is turned on. The driver 42 drives the magnet 41 to move in a circle along the annular slide rail 43 to homogenize the magnetic field on the target surface. The residual charge discharge circuit remains in standby mode. Then, the periodic synchronous potential control mode is activated by the active potential controller 30. Real-time parameters are collected by the plasma potential probe and the VI sensor (sampling rate ≥ 50MHz). During the positive half-cycle of the radio frequency, the shielding member 20 is activated. A +50V positive potential is applied to repel positive ions, and a -30V weak negative potential is applied during the negative half-cycle (this value is much less than the 100V critical threshold for particle resputtering). The ion energy analyzer and the arc detection module simultaneously monitor ion energy and discharge anomalies, and the insulation structure blocks potential leakage of the shielding device throughout the process. The lifting stage rises, bringing the wafer and the shielding device 20 into contact and defining the deposition area. The target material 10 generates a sputtering particle stream under the action of the radio frequency electric field and magnetic field, and the particles are deposited on the wafer surface to complete the coating. During this process, if the sensor data is abnormal, it immediately switches to a conservative safety mode with a continuous +50V positive potential.

[0107] This method balances particle contamination suppression with film quality improvement. The weak negative potential also enables ion-assisted deposition, resulting in a denser and more adhesive film. Synchronous potential control reduces RF power shunt loss. Multiple real-time monitoring and rapid protection mechanisms prevent potential runaway and arc damage. It not only blocks particle contamination caused by film peeling from the masking element 20 at the source, but also adapts to various process conditions, significantly improving process stability and wafer coating yield while ensuring film uniformity.

[0108] In summary, the RF magnetron sputtering apparatus with controllable cavity wall potential provided in this application, combined with a potential control method, implements precise potential regulation of the annular shield 20 through an active potential controller 30. At least during the positive half-cycle, a positive potential is applied to electrostatically repel positive ions, preventing particles from adhering and accumulating on the surface of the shield 20. Simultaneously, through a constant positive potential or a periodically varying potential mode synchronized with the RF, the negative potential during the negative half-cycle is strictly controlled below the particle re-sputtering threshold, fundamentally preventing particle contamination caused by film deposition and peeling on the shield surface. Combined with structures and strategies such as insulation isolation, safe disassembly and assembly, and high-speed closed-loop control, it avoids potential leakage, gas breakdown, and arc damage, while ensuring a uniform and stable sputtering electric field. It effectively suppresses instantaneous potential overshoot and plasma disturbances under RF operating conditions. While achieving precise definition of the wafer sputtering area, it significantly improves the cleanliness and uniformity of the coating, solving the problems of particle contamination, film defects, and poor process stability caused by uncontrollable cavity wall / shield potential in traditional RF magnetron sputtering apparatuses. This significantly improves wafer coating yield and equipment operational safety.

[0109] Furthermore, the active potential controller 30 employs a composite control strategy, which includes the following steps: The radio frequency voltage, radio frequency current, and phase difference between voltage and current on the shield 20 are collected in real time. At the same time, predictable process parameter disturbance signals are collected, including changes in the power setting value of the radio frequency power supply, changes in gas pressure or gas flow rate in the working chamber 2. Feedforward control is adopted to pre-calculate the compensation amount based on the collected disturbance signal, and adjust the capacitance value of the adjustable capacitor C and / or the output of the DC bias power supply in advance to suppress the instantaneous overshoot of the potential of the shield 20 caused by sudden changes in process parameters. Feedback control is adopted to compare the actual potential waveform of the shield 20 with the preset target potential waveform, calculate the deviation, and dynamically correct the capacitance value of the adjustable capacitor C and / or the output of the DC bias power supply according to the deviation. The feedback control is selected from at least one of the following algorithms: The model predictive control algorithm establishes a dynamic model of the interaction between the shield 20 and the plasma, predicts the system state for several steps in each control cycle, and solves for the optimal control quantity that makes the predicted trajectory approximate the preset target potential waveform. The sliding mode control algorithm is designed with the potential error of the shield 20 and its derivative as the state variables, and forces the system state to move along the sliding mode to enhance the robustness to plasma parameter perturbations and external disturbances. The adaptive control algorithm identifies and estimates the equivalent parameters of the load formed by the shield 20 and the plasma in real time through an online system, and automatically adjusts the parameters of the controller according to the identification results to adapt to changes in process conditions.

[0110] It should be explained that the composite control strategy is an optimized control scheme that combines feedforward control and feedback control. It eliminates the lag defect of simple closed-loop feedback. By real-time acquisition of the radio frequency electrical parameters of the shield and process disturbance signals such as radio frequency power, cavity gas pressure, and gas flow, the feedforward control calculates the compensation amount in advance and actively adjusts the adjustable capacitor and DC bias power supply to suppress potential overshoot caused by process mutations. Then, the feedback control compares the deviation between the actual and preset potential waveforms to dynamically correct the control amount, which greatly improves the response speed, accuracy and anti-interference ability of the shield potential control, and adapts to the strong nonlinear and time-varying load characteristics of plasma.

[0111] Among them, the model predictive control algorithm builds a dynamic model of the shield 20 and the plasma, predicts the subsequent state of the system and solves the optimal control quantity in each control cycle, and can actively adjust in advance, which is suitable for precision coating scenarios that require prediction of plasma changes.

[0112] The sliding mode control algorithm constructs a sliding surface using potential error and derivative, forcing the system to run along the sliding surface. It is extremely robust to parameter perturbations and external disturbances, and is suitable for working conditions with drastic fluctuations in plasma state.

[0113] The adaptive control algorithm identifies and estimates the equivalent load parameters of the system in real time online and automatically tunes the controller parameters without manual debugging. It is suitable for scenarios with frequent changes in process conditions. In actual use, the above algorithms can be selected individually or in combination according to the degree of process fluctuation, predicted needs and parameter switching frequency.

[0114] In one specific embodiment, the system operates at a main frequency of 13.56MHz. The preset target potential waveform of the shield 20 is +60V in the positive half-cycle and -25V in the negative half-cycle. The initial process settings are RF power of 300W, working chamber 2 pressure of 5mTorr, and argon flow rate of 50sccm. The active potential controller 30 uses an FPGA as its core, and is equipped with a piezoelectric ceramic driving vacuum variable capacitor C and a 16-bit programmable DC bias power supply to execute a composite control strategy.

[0115] During the coating process, the VI sensor collects the RF voltage, current, and phase difference signals of the shielding element 20 in real time. Simultaneously, the system collects process disturbance signals, namely, the RF power supply is stepped up to 400W and the gas pressure is fine-tuned to 6mTorr. The controller first uses feedforward control to quickly calculate the compensation amount based on this disturbance signal, pre-adjusting the capacitance of the adjustable capacitor C by 0.3pF and pre-adjusting the DC bias power supply output offset to suppress any instantaneous overshoot of the shielding element potential caused by sudden changes in power and gas pressure. Then, the model predictive control algorithm is activated, relying on a pre-established dynamic model of the interaction between the shielding element 20 and the plasma, to predict the subsequent... Following the three-step system potential status analysis, the actual potential waveform of the shield 20 collected by the VI sensor is compared with the preset target waveform to calculate the deviation. The optimal control quantity is then determined, and the capacitance value of the adjustable capacitor C and the DC bias power supply output are dynamically corrected. If the plasma state fluctuates drastically during the process, the sliding mode control algorithm can be switched on to construct a potential error sliding surface, quickly pulling the shield potential back to the target trajectory. If the target material 10 is replaced and the process conditions are changed subsequently, the adaptive control algorithm will automatically adjust the controller parameters by identifying the equivalent load parameters online, ensuring that the absolute value of the negative potential of the shield 20 is always below the critical value during the negative half-cycle, thus preventing both particle re-sputtering and potential runaway problems.

[0116] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A radio frequency magnetron sputtering device with controllable cavity wall potential, characterized in that, include: The sputtering source cavity (1) is used to mount the target material (10), which is connected to the radio frequency power supply. The radio frequency power supply is able to output a periodically changing radio frequency electric field, and each cycle of the radio frequency electric field includes a positive half-cycle and a negative half-cycle. The working cavity (2) is connected to the sputtering source cavity (1). The working cavity (2) is provided with a lifting platform for supporting the wafer, and the target material (10) is facing the lifting platform. The shield (20) is made of conductive material and is arranged in a ring shape. It is located in the working cavity (2), below the target (10), and around the sputtering surface of the target (10). It is used to abut against the wafer on the lifting platform when the lifting platform is raised to define the deposition area of ​​sputtered particles. An active potential controller (30), electrically connected to the shield (20), is used to apply a potential to the shield (20) so that the shield (20) can repel positively charged particles at least during the positive half-cycle, thereby inhibiting the attachment of particles to the shield (20). The active potential controller (30) is configured to keep the shield (20) at a positive potential. The active potential controller (30) is used to apply a constant positive DC bias to the shield (20). The value of the positive DC bias is set to be higher than the maximum fluctuation value of the plasma potential during the radio frequency discharge process, so as to always form a stable electrostatic barrier that repels positive ions on the surface of the shield (20) throughout the entire radio frequency cycle. Alternatively, the active potential controller (30) is configured to cause the potential of the shield (20) to change periodically in sync with the radio frequency power supply, wherein the shield (20) presents a positive potential during the positive half-cycle and a negative potential during the negative half-cycle, and the absolute value of the negative potential is configured to be less than a threshold that can attract positive ions to bombard particles attached to the shield (20).

2. The radio frequency magnetron sputtering device with controllable cavity wall potential according to claim 1, characterized in that, When the active potential controller (30) is configured to keep the shield (20) continuously at a positive potential, the active potential controller (30) includes: A DC bias power supply is used to continuously apply a constant positive DC voltage to the shield (20) so that the shield (20) is always at a positive potential throughout the entire cycle of the radio frequency electric field; A filter network is connected between the DC bias power supply and the shield (20) to prevent radio frequency energy from entering the DC bias power supply.

3. The radio frequency magnetron sputtering apparatus with controllable cavity wall potential according to claim 1, characterized in that, When the active potential controller (30) is configured to cause the potential of the shield (20) to change periodically in sync with the radio frequency power supply, the active potential controller (30) includes: An adjustable impedance matching network, connected between the shield (20) and the reference ground, includes a fixed inductor (L1) and an adjustable capacitor (C) for adjusting the radio frequency impedance of the shield (20) so that the potential of the shield (20) changes synchronously with the period of the radio frequency power supply. A DC bias power supply is connected to the shield (20) via an isolation inductor (L2) to provide a programmable DC bias voltage to the shield (20); A VI sensor is connected between the shield (20) and the adjustable impedance matching network for real-time measurement of the radio frequency current flowing through the shield (20), the voltage to ground, and their phase difference. The controller is connected to the VI sensor, the adjustable capacitor (C) and the DC bias power supply respectively, and is used to control the capacitance value of the adjustable capacitor (C) and / or the output of the DC bias power supply in a closed loop according to the measurement result of the VI sensor, so as to dynamically maintain the preset potential waveform of the shield (20).

4. The radio frequency magnetron sputtering device with controllable cavity wall potential according to claim 3, characterized in that, The active potential controller (30) also includes an ion energy analyzer, which is located adjacent to the shield (20) and is used to measure the positive ion energy distribution and ion flux density bombarded to the surface of the shield (20) in real time. The controller is connected to the ion energy analyzer and is configured to reduce the absolute value of the negative bias voltage of the shield (20) or increase the positive bias voltage of the shield (20) when the ion energy analyzer detects that the ion energy on the surface of the shield (20) exceeds a preset critical sputtering threshold. And / or, the active potential controller (30) further includes a plasma potential probe, which is disposed in the working cavity (2) for measuring the plasma potential in real time. The controller is connected to the plasma potential probe and is configured to dynamically adjust the preset potential waveform of the shield (20) according to the difference between the plasma potential and the reference ground potential, so that the absolute value of the negative potential of the shield (20) in the negative half-cycle is always less than the difference, thereby avoiding attracting high-energy positive ion bombardment; And / or, the sampling rate of the VI sensor is not less than 50MHz, used to acquire the instantaneous waveform of the radio frequency voltage and current on the shield (20), and the controller is configured to calculate the actual potential peak of the shield (20) in each radio frequency cycle based on the instantaneous waveform and compare it with the preset target waveform to correct the capacitance value of the adjustable capacitor (C) and / or the output of the DC bias power supply; And / or, the active potential controller (30) further includes an arc detection module, which is connected to the VI sensor and is used to monitor the rate of change of voltage and / or current spikes on the shield (20) to identify arc events. The controller is connected to the arc detection module and is configured to forcibly switch the potential of the shield (20) to a preset positive safe potential within microseconds when an arc event is detected, and restore the preset target waveform after the arc is extinguished. And / or, the VI sensor is configured to extract harmonic components of the operating frequency of the radio frequency power supply, the harmonic components including second harmonics and / or third harmonics, and the controller is configured to analyze the amplitude and phase changes of the harmonic components to diagnose the microstate of the plasma and to warn that the negative potential of the shield (20) may exceed a critical threshold when the harmonic components show abnormal changes. And / or, the active potential controller (30) further includes a dual-channel redundant measurement unit, which includes two independently configured VI sensors. The two sets of VI sensors are respectively arranged at different positions or different electrical connection points of the shield (20). The controller is connected to the two sets of VI sensors and is configured to cross-verify the two measurement data. When the deviation between the two data exceeds a preset threshold, it is judged as a sensor failure and the potential of the shield (20) is automatically switched to a conservative safety mode. The conservative safety mode is a continuous positive potential. And / or, the adjustable capacitor (C) is a piezoelectric ceramic driven vacuum variable capacitor with an adjustment accuracy of ±0.1pF; And / or, the DC bias power supply is a programmable DC power supply with a resolution of 16 bits or higher; And / or, the controller is a field-programmable gate array, and its control cycle is no more than 1 microsecond.

5. The radio frequency magnetron sputtering apparatus with controllable cavity wall potential according to claim 1, characterized in that, Insulation structures are provided between the shield (20) and the sputtering source cavity (1), and between the shield (20) and the working cavity (2), to prevent the potential on the shield (20) from leaking to other grounded or floating components; Or, the shield (20) and the target (10) are electrically isolated by a physical gap, the distance of which is configured to be greater than the Paschen breakdown distance corresponding to the maximum potential difference between the shield (20) and the target (10) to avoid gas breakdown. The upper end face of the shield (20) is higher than the sputtering surface of the target (10), so that the gap between them is located within the line-of-sight deposition shadow area of ​​the sputtered particle stream of the target (10), thereby avoiding electrical short circuits caused by the deposition of conductive films in the physical gap.

6. The radio frequency magnetron sputtering apparatus with controllable cavity wall potential according to claim 1, characterized in that, Also includes: The first electrical contact portion is provided on the shield (20); The second electrical contact is located inside the working cavity (2) and is electrically connected to the output terminal of the active potential controller (30). The shield (20) is detachably disposed within the working cavity (2); After the shield (20) is installed in place, the first electrical contact part is connected to the second electrical contact part and conduction is achieved, so as to realize the electrical connection between the shield (20) and the active potential controller (30); The cavity wall potential controllable radio frequency magnetron sputtering device also includes a disassembly and assembly safety protection unit, which includes at least one of the following: Insulation removal and installation tools, which are matched with the disassembly operation parts of the shield (20), are used to prevent the operator from directly contacting the conductor; The cavity door interlock switch is connected in series with the power enable terminal of the active potential controller (30) and is used to automatically cut off the power supply to the shield (20) when the cavity door is opened; A residual charge discharge circuit is connected in parallel between the output terminal of the active potential controller (30) and the reference ground, and is used to quickly discharge the potential of the shield (20) to a safe value after power failure.

7. The radio frequency magnetron sputtering apparatus with controllable cavity wall potential according to claim 1, characterized in that, It also includes a magnetic field generating mechanism disposed within the sputtering source cavity (1), the magnetic field generating mechanism comprising: A magnet (41) is positioned above the target material (10); A rotary drive assembly is used to drive the magnet (41) to make circular motion in order to homogenize the magnetic field of the target surface; The radio frequency magnetron sputtering device with controllable cavity wall potential also includes a symmetrical frame conductive structure disposed in the sputtering source cavity (1). The symmetrical frame conductive structure includes a circular top surface (51) and a cylindrical wall surface (52). The magnetic field generating mechanism is disposed in the space enclosed by the cylindrical wall surface (52). Both the circular top surface (51) and the cylindrical wall surface (52) are made of conductive material. The top of the cylindrical wall surface (52) is connected to the circular top surface (51), and the bottom of the cylindrical wall surface (52) is connected to the target material (10). A power terminal (53) is provided at the center of the circular top surface (51). The power terminal (53) passes through the top of the sputtering source cavity (1) and is connected to the radio frequency power supply located outside. The symmetrical frame conductive structure is used to uniformly diffuse radio frequency energy radially from the center of the circular top surface (51), and then uniformly conduct it axially to the central region of the target material (10) through the cylindrical wall surface (52).

8. The radio frequency magnetron sputtering apparatus with controllable cavity wall potential according to any one of claims 1-7, characterized in that, The shell of the sputtering source cavity (1) is a double-layer composite structure, with the outer layer being a grounded electromagnetic shielding layer (1a) and the inner layer being an insulating support layer (1b).

9. A potential control method, implemented based on the radio frequency magnetron sputtering device with controllable cavity wall potential as described in any one of claims 1-8, characterized in that, Includes the following steps: A target (10) is provided to be connected to an RF power supply and generates a periodically changing RF electric field, each cycle of which includes a positive half-cycle and a negative half-cycle; By means of an active potential controller (30), a positive potential is applied to the shield (20) at least in each positive half-cycle to suppress the movement and attachment of positively charged particles to the shield (20) in an electrostatic repulsive manner; During the sputtering process, a constant positive potential is applied to the shield (20) throughout the entire cycle of the radio frequency electric field, or the potential of the shield (20) is periodically changed in sync with the radio frequency electric field, so that the shield (20) presents a positive potential during the positive half-cycle and a negative potential during the negative half-cycle, and the absolute value of the negative potential is controlled to be insufficient to cause re-sputtering of particles attached to the shield (20).

10. The potential control method according to claim 9, characterized in that, The active potential controller (30) adopts a composite control strategy, which includes the following steps: The radio frequency voltage, radio frequency current, and phase difference between voltage and current on the shield (20) are collected in real time. At the same time, process parameter disturbance signals are collected. The disturbance signals include changes in the power setting value of the radio frequency power supply, changes in air pressure or gas flow rate in the working chamber (2). Feedforward control is adopted, and the compensation amount is calculated in advance based on the collected disturbance signal. The capacitance value of the adjustable capacitor (C) and / or the output of the DC bias power supply are adjusted in advance to suppress the instantaneous overshoot of the potential of the shield (20) caused by the sudden change of process parameters. Feedback control is adopted to compare the actual potential waveform of the shield (20) with the preset target potential waveform, calculate the deviation, and dynamically correct the capacitance value of the adjustable capacitor (C) and / or the output of the DC bias power supply according to the deviation. The feedback control is selected from at least one of the following algorithms: The model predictive control algorithm establishes a dynamic model of the interaction between the shield (20) and the plasma, predicts the future system state in each control cycle, and solves the optimal control quantity that makes the predicted trajectory approximate the preset target potential waveform. The sliding mode control algorithm designs a sliding surface with the potential error of the shield (20) and its derivative as the state variables, and forces the system state to move along the sliding surface to enhance the robustness to plasma parameter perturbations and external disturbances. The adaptive control algorithm identifies and estimates the equivalent parameters of the load formed by the shield (20) and the plasma in real time through an online system, and automatically adjusts the parameters of the controller according to the identification results to adapt to changes in process conditions.

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