A control system and method for an inductively coupled plasma device

Abstract

This invention discloses a control system and method for inductively coupled plasma (ICP) equipment, belonging to the field of semiconductor equipment technology. The control system includes a vacuum chamber module, a plasma parameter diagnostic module, and a radio frequency (RF) current phase control module. Several inductors are mounted above the vacuum chamber module. The vacuum chamber module maintains the base vacuum and pressure environment of the chamber. The plasma parameter diagnostic module acquires the plasma parameters within the vacuum chamber module. The RF current phase control module acquires the plasma parameters and the current phase of the inductors, and issues RF control signals to control the inductors based on the plasma parameters and current phase. This invention, through a three-level collaborative architecture and a dual-input closed-loop control strategy using plasma parameters and inductor current phase, solves the core problems of uncontrollable current phase and strong parameter coupling in a single RF power supply open-loop architecture, significantly improving the in-plane uniformity and batch repeatability of large-size wafer processes.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor equipment technology, and particularly relates to an inductively coupled plasma equipment control system and method. Background Technology

[0002] Inductively Coupled Plasma (ICP), with its core advantages of high electron density, high ionization efficiency, low electron temperature, and wide range of process parameter control, has completely replaced traditional capacitively coupled plasma, becoming the standard equipment for core processes in advanced semiconductor manufacturing such as dry etching, atomic layer deposition, and plasma-enhanced chemical vapor deposition. As semiconductor processes advance to 3nm, 2nm, and even more advanced nodes, and wafer sizes increase to 12 inches, device structures exhibit high aspect ratios and three-dimensional stacking characteristics. This places extremely stringent demands on the in-plane uniformity of plasma, etching selectivity, and the precision of topographic contour control. The controllability of traditional ICP equipment is approaching its physical limits.

[0003] Current mainstream ICP equipment generally adopts a coaxial internal / external dual-coil architecture, and conventional control methods are limited to adjusting only three parameters: total RF power, chamber pressure, and the power ratio of the internal and external coils. This approach has an inherent flaw: there is a strong coupling relationship between core plasma parameters such as electron density, electron temperature, ion energy, and ion flux. Adjusting a single parameter will trigger a chain reaction of changes in the others, making it impossible to achieve independent and precise control of a single parameter and difficult to simultaneously meet the process consistency requirements of the wafer center and edge regions.

[0004] More importantly, existing technologies all employ a strongly coupled open-loop architecture with a single RF power supply and a power divider, resulting in extremely limited phase control capabilities. The industry can only achieve a fixed 180° phase difference by reversing the coil windings, or by adding passive phase-shifting circuits to provide a few discrete current phase levels, completely lacking dynamic closed-loop control capabilities. Under dynamic ICP load conditions such as impedance abrupt changes at plasma ignition, gas component drift during the process, and chamber temperature variations, the current phase will drift uncontrollably, making continuous adjustment across the entire 0°~360° range impossible. Simultaneously, the inherent mutual inductance coupling effect between multiple coils further interferes with the current phase, leading to a significant decrease in phase control accuracy, failing to support the refined control requirements of advanced processes for the spatiotemporal distribution of plasma. Summary of the Invention

[0005] Based on the technical problems existing in the prior art, the present invention provides an inductively coupled plasma device control system and method.

[0006] According to a first aspect of the technical solution of the present invention, the present invention provides an inductively coupled plasma device control system, which includes a vacuum chamber module, a plasma parameter diagnostic module, and a radio frequency current phase control module. A plurality of inductor coils are disposed above the vacuum chamber module. The vacuum chamber module is used to maintain the background vacuum and gas pressure environment of the chamber. The plasma parameter diagnostic module is used to acquire the plasma parameters in the vacuum chamber module. The radio frequency current phase control module is used to acquire the plasma parameters and the current phase of the inductor coils, and to send radio frequency control signals to control the inductor coils according to the plasma parameters and the current phase.

[0007] A further improvement of the present invention is that the top of the vacuum chamber module is a quartz top plate.

[0008] A further improvement of the present invention is that: the vacuum chamber module is further provided with a vacuum pump, a worktable and a gas inlet assembly, the vacuum pump is located at the bottom of the vacuum chamber module, the worktable is located above the bottom surface of the vacuum chamber module, and the gas inlet of the gas inlet assembly is located at the top of the vacuum chamber module.

[0009] A further improvement of the present invention is that: the number of groups of the plurality of inductors is greater than or equal to two, and the plurality of inductors are all three-dimensional planar spiral inductors wound in the same direction or planar spiral inductors wound in the same direction.

[0010] A further improvement of the present invention is that the plasma parameter diagnostic module includes a spectrometer main control unit and an optical fiber probe, wherein the optical fiber probe is connected to the spectrometer main control unit via an optical fiber.

[0011] A further improvement of the present invention is that the radio frequency current phase control module includes a radio frequency excitation unit, a radio frequency adjustment unit, and a current phase closed-loop control unit. The radio frequency excitation unit is used to output a radio frequency voltage waveform. The radio frequency adjustment unit is used to acquire the radio frequency voltage waveform and allocate the radio frequency voltage waveform into several radio frequency signals. The current phase closed-loop control unit is used to adjust the several radio frequency signals according to the current phase and plasma parameters to obtain a radio frequency control signal and output the radio frequency control signal to the inductor coil.

[0012] A further improvement of the present invention is that the radio frequency conditioning unit includes a power divider D1, the power divider D1 outputs two branches, each branch is provided with two vacuum adjustable capacitors, and an L-type matching network is provided between the two vacuum adjustable capacitors on the same branch.

[0013] A further improvement of the present invention is that the current phase closed-loop control unit includes a first current phase detection component and a second current phase detection component, both of which are electrically connected to the closed-loop control component.

[0014] A further improvement of the present invention is that the first current phase detection component and the second current phase detection component are Rogowski coil current detection circuits.

[0015] According to a second aspect of the technical solution of the present invention, a control method for an inductively coupled plasma device is provided, which is based on the above-described control system and includes the following steps: Step S1: Maintain the background vacuum and pressure environment of the vacuum chamber through the vacuum chamber module; Step S2: Obtain the plasma parameters within the vacuum chamber module through the plasma parameter diagnostic module; Step S3: Obtain the plasma parameters and the current phase of the inductor coil through the radio frequency current phase control module; Step S4: The radio frequency current phase control module generates a radio frequency control signal based on the plasma parameters; Step S5: Control the inductor coil through the radio frequency control signal.

[0016] Compared with the prior art, the above-mentioned technical solution of the present invention has the following beneficial technical effects: 1. This invention solves the core problems of uncontrollable current phase and strong parameter coupling in the traditional ICP equipment under the single RF power supply open-loop architecture by integrating a vacuum chamber module, a plasma parameter diagnosis module and an RF current phase control module, and adopting a dual-input closed-loop control strategy of plasma parameters and inductor coil current phase. It significantly improves the in-plane uniformity and batch repeatability of large-size wafer processes and can support the high precision requirements of advanced semiconductor processes for etching and deposition processes.

[0017] 2. This invention solves the problem of balancing vacuum sealing and efficient radio frequency energy transmission by setting a quartz top plate as a dielectric isolation component on the top of the vacuum chamber module. It utilizes the extremely low gas permeability, excellent high temperature resistance, and low dielectric loss characteristics of high-purity fused silica material. This not only reliably maintains the high vacuum environment of the chamber, but also ensures that the alternating magnetic field generated by the inductor coil enters the ionized gas in the chamber without significant attenuation. At the same time, it avoids the coil being directly exposed to plasma and corroded, thus greatly extending the service life of the core components.

[0018] 3. By placing the vacuum pump at the bottom of the vacuum chamber module, the worktable above the bottom surface, and the gas inlet of the gas inlet assembly at the top of the chamber, this invention achieves synergistic optimization of gas extraction, workpiece bearing, and gas distribution. It solves the problems of uneven gas distribution and low extraction efficiency in traditional layouts. It can quickly pump the chamber to a high background vacuum and maintain a stable process gas pressure, providing a clean and uniform basic environment for plasma generation and maintenance, and ensuring the stability and consistency of process parameters from the source.

[0019] 4. This invention employs two or more sets of three-dimensional or planar spiral inductor coils wound in the same direction. By utilizing the principle of superimposing the magnetic fields of the coils in the same direction to enhance the magnetic field strength in the central region, and combining current phase adjustment methods, it solves the bottleneck problem that the uniformity of single-coil plasma decreases sharply as the cavity size increases. It achieves precise and controllable radial distribution of plasma, enabling the acquisition of high-density plasma with good uniformity in large-size cavities, while significantly improving the coupling efficiency between radio frequency energy and plasma.

[0020] 5. This invention employs an optical emission spectroscopy diagnostic module composed of a spectrometer main control unit and an optical fiber probe. It utilizes non-contact spectral detection technology to acquire plasma characteristic spectra in real time and analyze key parameters. This solves the problems of traditional invasive diagnostic methods that interfere with the normal state of plasma and have slow response speed. It enables online, real-time, and high-precision measurement of parameters such as electron temperature, electron density, and active group concentration. This provides accurate and timely feedback signals for radio frequency phase closed-loop control, significantly improving the response speed and control accuracy of the control system.

[0021] 6. This invention divides the radio frequency current phase control module into three functional sub-modules: a radio frequency excitation unit, a radio frequency adjustment unit, and a current phase closed-loop control unit. This achieves a decoupled design for radio frequency energy generation, distribution, and closed-loop control, solving the problems of insufficient phase control capability and mutual interference between multiple branches in traditional integrated radio frequency systems. It can independently adjust the phase and amplitude of each radio frequency signal, and at the same time, it can dynamically correct parameter drift through real-time feedback, significantly improving the stability of plasma and process repeatability, and reducing the difficulty of system debugging and maintenance.

[0022] 7. This invention achieves independent power distribution and impedance matching for the two RF signals by using a power divider to output two independent branches in the RF conditioning unit, with two vacuum adjustable capacitors in each branch and an L-shaped matching network in the middle. This solves the problems of crosstalk between multiple branches and excessive reflected power, and can control the reflected power to an extremely low level. This ensures that the two coils obtain stable and independent RF power, greatly improves the RF energy utilization rate, and effectively avoids the risk of damage to the RF power source due to excessive reflected power.

[0023] 8. This invention achieves synchronous detection and closed-loop feedback control of the current phase of two inductor coils by setting first and second current phase detection components in the current phase closed-loop control unit and electrically connecting their output terminals to the closed-loop control component. This solves the problem of uncontrollable current phase due to sudden changes in load impedance, component parameter differences, and temperature drift in traditional open-loop control. It can correct phase deviation in real time and lock it within the target range, eliminating the uneven plasma distribution caused by phase inconsistency from the root cause and ensuring the stability and consistency of the process.

[0024] 9. This invention uses a Rogowski coil current detection circuit as the current phase detection component. By utilizing its hollow ring non-contact measurement principle and wide bandwidth and high linearity, it solves the problems of high insertion loss and interference with the main circuit operation in high-frequency high-current detection. It can accurately detect the current waveform and phase in commonly used radio frequency bands such as 13.56MHz, providing a reliable feedback signal for current phase closed-loop control. At the same time, it simplifies the circuit structure and improves the stability and service life of the detection system.

[0025] 10. This invention adopts a step-by-step control method of "process parameter preset - initial parameter matching - chamber environment preparation - plasma ignition and phase locking - environmental stabilization - parameter readjustment - full-process stable control", combined with a dual closed-loop control strategy of plasma parameters and current phase. It solves the problem of strong parameter coupling and inability to independently and accurately control the parameters in the traditional ICP control method, and realizes all-round, high-precision dynamic control of plasma state. It can effectively compensate for parameter drift in the process, significantly improve the accuracy, uniformity and batch repeatability of etching, deposition and other processes, and is suitable for the stringent process requirements of advanced semiconductor manufacturing. Attached Figure Description

[0026] The accompanying drawings are provided to better understand the invention and are not intended to unduly limit the scope of the invention. Wherein: Figure 1 This is a structural block diagram of an inductively coupled plasma device control system according to the present invention; Figure 2 This is a circuit diagram of the radio frequency adjustment unit in the control system of an inductively coupled plasma device according to the present invention; Figure 3 This is a structural diagram of the current phase closed-loop control unit in the control system of an inductively coupled plasma device according to the present invention.

[0027] Figure 4 This is a schematic diagram of the integrating circuit of a single-supply Rogowski coil in an inductively coupled plasma device control system according to the present invention.

[0028] Explanation of reference numerals in the attached figures: 10-Vacuum chamber module; 101-Vacuum pump; 102-Worktable; 103-Wafer; 104-Quartz top plate; 105-Gas inlet assembly; 106-Inductor coil; 20-Plasma parameter diagnostic module; 201-Spectrometer main control unit; 202-Fiber optic probe; 30-RF current phase control module; 301-RF excitation unit; 302-RF adjustment unit; 303-Current phase closed-loop control unit; 304-First current phase detection assembly; 305-Second current phase detection assembly; 306-Closed-loop control assembly. Detailed Implementation

[0029] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of the present invention, including various details to aid understanding. These details should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0030] This invention discloses a control system and method for inductively coupled plasma (ICP) equipment, belonging to the field of semiconductor equipment technology. The control system includes a vacuum chamber module, a plasma parameter diagnostic module, and a radio frequency (RF) current phase control module. Several inductors are mounted above the vacuum chamber module. The vacuum chamber module maintains the base vacuum and pressure environment of the chamber. The plasma parameter diagnostic module acquires the plasma parameters within the vacuum chamber module. The RF current phase control module acquires the plasma parameters and the current phase of the inductors, and issues RF control signals to control the inductors based on the plasma parameters and current phase. This invention, through a three-level collaborative architecture and a dual-input closed-loop control strategy using plasma parameters and inductor current phase, solves the core problems of uncontrollable current phase and strong parameter coupling in a single RF power supply open-loop architecture, significantly improving the in-plane uniformity and batch repeatability of large-size wafer processes.

[0031] The technical solution of the inductively coupled plasma device control system and method of the present invention will be described in detail below with reference to embodiments and accompanying drawings.

[0032] Example 1 like Figure 1As shown, an inductively coupled plasma (ICP) device control system is provided, comprising a vacuum chamber module 10, a plasma parameter diagnostic module 20, and a radio frequency (RF) current phase control module 30. Several inductor coils 106 are disposed above the vacuum chamber module 10. The vacuum chamber module 10 is used to maintain the background vacuum and pressure environment of the chamber. The plasma parameter diagnostic module 20 is used to acquire plasma parameters within the vacuum chamber module 10. The RF current phase control module 30 is used to acquire the plasma parameters and the current phase of the inductor coils 106, and to issue RF control signals to control the inductor coils 106 based on the plasma parameters and the current phase. The system adopts a three-level collaborative architecture of vacuum environment maintenance, real-time plasma diagnostics, and RF phase closed-loop control, achieving high-precision and high-stability control of the ICP. During operation, the vacuum chamber module 10 first evacuates the chamber to a preset base vacuum and introduces process gas to maintain a stable pressure. Then, the RF current phase control module 30 outputs RF current to the inductor coil 106, generating an alternating electromagnetic field that ionizes the process gas to form plasma. Simultaneously, the plasma parameter diagnostic module 20 acquires the plasma's spectral signal in real time and analyzes it into key parameters. The RF current phase control module 30 synchronously detects the current phase of each group of inductor coils 106, using plasma parameters and current phase as dual input variables for closed-loop calculation, generating an adjusted RF control signal that is fed back to the inductor coil 106 to dynamically correct the plasma's density, temperature, and spatial distribution. This system, by introducing current phase closed-loop control, solves the problems of poor plasma uniformity and low process repeatability caused by inconsistent current phases in multiple coils in traditional ICP equipment, significantly improving the accuracy and yield of etching, deposition, and other processes.

[0033] Specifically, the top of the vacuum chamber module 10 is a quartz top plate 104. The quartz top plate 104 is a key dielectric isolation component between the vacuum chamber and the inductor coil 106. It is made of high-purity fused silica material. On the one hand, quartz material has extremely low gas permeability and excellent high-temperature resistance, enabling reliable sealing of the vacuum chamber and maintenance of a high-vacuum environment inside. On the other hand, quartz has extremely low dielectric loss in commonly used radio frequency bands, allowing efficient transmission of radio frequency electromagnetic fields, ensuring that the alternating magnetic field generated by the inductor coil 106 can enter the vacuum chamber without significant attenuation to ionize the process gas. During operation, the quartz top plate 104 is constantly subjected to the high-temperature radiation and ion bombardment of the plasma, while simultaneously isolating the vacuum environment from the external atmospheric environment. This ensures the sealing and stability of the vacuum system, minimizes radio frequency energy loss, and prevents the inductor coil 106 from being directly exposed to the plasma environment and corroded, thus extending the coil's service life.

[0034] Specifically, the vacuum chamber module 10 also includes a vacuum pump 101, a worktable 102, and a gas inlet assembly 105. The vacuum pump 101 is located at the bottom of the vacuum chamber module 10, the worktable 102 is located above the bottom surface of the vacuum chamber module 10, and the gas inlet of the gas inlet assembly 105 is located at the top of the vacuum chamber module 10. The worktable 102 is used to place the wafer 103 to be processed. The vacuum pump 101 typically employs a multi-stage pumping combination. First, the primary pump evacuates the chamber from atmospheric pressure to a low vacuum, and then the secondary pump continues to evacuate to a high background vacuum, continuously removing residual gases and process byproducts from the chamber. The worktable 102 is used to support the workpiece to be processed. It typically integrates a temperature control device and a workpiece fixing mechanism, which can heat the workpiece to a preset process temperature and fix the workpiece, ensuring the positional accuracy of the workpiece during the process. The gas inlet assembly 105 consists of a flow control unit and a gas distributor. After the system starts, the vacuum pump 101 first works to evacuate to the background vacuum. Then, the gas inlet assembly 105 introduces process gas at a set flow rate, and the vacuum pump 101 continuously evacuates to maintain the chamber at the preset process gas pressure. This provides a clean and stable vacuum and pressure environment for the generation and maintenance of plasma, ensuring the uniform distribution of process gas and laying the foundation for obtaining uniform plasma.

[0035] Specifically, the number of sets of inductor coils 106 is greater than or equal to two, and all inductor coils 106 are either three-dimensional planar helical inductor coils wound in the same direction or planar helical inductor coils wound in the same direction. The inductor coils 106 are the core energy coupling components for generating plasma. Based on the law of electromagnetic induction, when radio frequency current passes through the coil, an alternating axial magnetic field is generated around the coil. This alternating magnetic field induces a vortex electric field within the vacuum chamber. The vortex electric field accelerates electrons, causing them to collide with and ionize process gas molecules, forming a high-density inductively coupled plasma. The design using two or more sets of coils wound in the same direction allows the magnetic fields generated by the coils to superimpose, significantly enhancing the magnetic field strength in the central region of the chamber. Simultaneously, by adjusting the current phase of each set of coils, the radial distribution of the plasma can be precisely controlled. Three-dimensional helical inductor coils are suitable for large-size chambers and can generate deeper plasma regions; planar helical inductor coils have a compact structure and are suitable for small chambers with high space requirements. During operation, the RF current phase control module 30 outputs independent RF signals to each group of coils. By adjusting the phase and amplitude of the current, precise control of the plasma density distribution is achieved. This overcomes the bottleneck that the plasma uniformity of a single coil decreases as the chamber size increases, enabling the acquisition of highly uniform plasma in large-size chambers while simultaneously improving plasma density and energy coupling efficiency.

[0036] Specifically, the plasma parameter diagnostic module 20 includes a spectrometer main control unit 201 and an optical fiber probe 202, which is connected to the spectrometer main control unit 201 via optical fiber. The plasma parameter diagnostic module 20 may also employ a Langmuir probe or an ion energy analyzer, among other plasma detection systems. The optical fiber probe 202 is installed at the observation window of the vacuum chamber module 10. Using optical emission spectroscopy diagnostic technology, the characteristic spectra emitted by excited-state atoms and ions in the plasma when transitioning back to the ground state are utilized. The optical fiber probe 202 collects these characteristic spectral signals and transmits them to the spectrometer main control unit 201 via a low-loss silica optical fiber. The spectrometer main control unit 201 has a built-in spectroscopic system and photodetector array, which decomposes the incident light into spectra of different wavelengths. By analyzing the intensity, wavelength, and half-width at half-maximum (WHM) of the characteristic spectral lines, key parameters such as the plasma's electron temperature, electron density, ion concentration, types of active groups, and their relative abundance are calculated. The analyzed plasma parameters are then transmitted in real-time to the radio frequency current phase control module 30. It enables online, real-time, and non-invasive measurement of plasma parameters without interfering with the normal state of the plasma, providing accurate and timely feedback signals for radio frequency phase closed-loop control, and significantly improving the response speed and control accuracy of the control system.

[0037] Specifically, the radio frequency (RF) current phase control module 30 includes an RF excitation unit 301, an RF adjustment unit 302, and a current phase closed-loop control unit 303. The RF excitation unit 301 outputs an RF voltage waveform. The RF adjustment unit 302 acquires the RF voltage waveform and distributes it into several RF signals. The current phase closed-loop control unit 303 adjusts the several RF signals according to the current phase and plasma parameters to obtain an RF control signal, which is then output to the inductor coil 106. The RF excitation unit 301 is typically a solid-state RF power source that generates a stable reference RF signal through a crystal oscillator. After amplification by a power amplifier, it outputs a high-power RF voltage waveform, the output power of which can be adjusted within a certain range. The core function of the RF adjustment unit 302 is power distribution and impedance matching. It receives the RF signal from the RF excitation unit 301, distributes it at equal power or according to a preset ratio into multiple signals corresponding to the number of inductor coil groups, and performs independent impedance matching adjustment on each signal to ensure that RF energy can be transmitted to the inductor coil 106 to the maximum extent and reduce reflected power. The current phase closed-loop control unit 303 employs a dual-input closed-loop control algorithm. It simultaneously receives plasma parameters from the plasma parameter diagnostic module 20 and the current phase of each coil from the current phase detection component. It compares the actual parameters with preset process parameters, calculates the adjustment amounts for phase and power, and generates an RF control signal that is fed back to the RF adjustment unit 302 to dynamically adjust the phase and amplitude of each RF signal. The RF excitation unit 301 outputs an initial RF signal, which is distributed and matched by the RF adjustment unit 302 and then sent to the inductor coil 106. The current phase closed-loop control unit 303 acquires the feedback signal in real time and performs closed-loop calculations, continuously adjusting the RF signal until the plasma parameters reach the preset values ​​and remain stable. This achieves independent phase and power control of multiple RF signals. The dual-input closed-loop control significantly improves plasma stability and process repeatability, effectively solving the problems of parameter drift and poor uniformity in traditional open-loop control.

[0038] like Figure 2As shown, specifically, the RF conditioning unit 302 includes a power divider D1. Power divider D1 outputs two branches, each with two adjustable vacuum capacitors. An L-type matching network is provided between the two adjustable vacuum capacitors on the same branch. Power divider D1 can be any type of power divider, such as a waveguide power divider or a Wilkinson power divider. Power divider D1 is designed for a 13.56MHz 3kW RF output, achieving a 1-to-2 continuously adjustable power distribution from 0 to 3kW, with a total efficiency ≥95%, VSWR ≤1.2:1, and isolation ≥20dB. It employs a transmission line transformer power divider + adjustable L-type matching structure at the output end, using two parallel TDKPC44 magnetic rings. Power adjustment is achieved through a fixed inductor and adjustable vacuum capacitors, utilizing impedance changes to control the power distribution ratio, allowing for arbitrary proportions. An isolation resistor is configured at the output end to enhance port isolation. A microcontroller controls a stepper motor to drive the capacitors, achieving high power capacity, a wide adjustment range, and low loss, expandable to 3-4 outputs. Figure 2 As shown, the power divider D1 outputs two branches. One branch has a vacuum adjustable capacitor C1 and a vacuum adjustable capacitor C5. A first L-type matching network is provided between the vacuum adjustable capacitor C1 and the vacuum adjustable capacitor C5. The first L-type matching network includes a vacuum adjustable capacitor C3 and an inductor L1.

[0039] Branch 2 includes a vacuum adjustable capacitor C2 and a vacuum adjustable capacitor C6. A second L-shaped matching network is provided between the vacuum adjustable capacitors C2 and C6. The second L-shaped matching network includes a vacuum adjustable capacitor C4 and an inductor L2. The L-shaped matching network is used to adjust the impedance matching between the RF excitation unit 301 and the vacuum chamber module 10.

[0040] like Figure 3As shown, specifically, the current phase closed-loop control unit 303 includes a first current phase detection component 304 and a second current phase detection component 305, both of which are electrically connected to the closed-loop control component 306. This unit achieves precise closed-loop control of the two sets of coil current phases through dual-channel current phase detection. The first current phase detection component 304 and the second current phase detection component 305 are located in two RF branches, respectively, and are used to detect the RF current waveform and phase of the inductor coil 106 in real time. The closed-loop control component 306 uses a programmable logic device or digital signal processor as its core controller, and incorporates a high-speed analog-to-digital converter and digital signal processing algorithms. Two current phase detection components convert the detected current signals into voltage signals, which are then input into the closed-loop control component 306. The closed-loop control component 306 samples and calculates the phase difference between the two current signals. Simultaneously, it combines the plasma parameters input from the plasma parameter diagnostic module 20 with a suitable control algorithm to calculate the phase adjustment and power adjustment amounts. The control signal is then output to the vacuum adjustable capacitor of the RF adjustment unit 302 to adjust the phase and amplitude of each RF signal. After system startup, the closed-loop control component 306 first sets the target phase difference between the two coils, then collects the actual phase difference between the two currents in real time and compares it with the target value. If a deviation exists, a control signal is output to adjust the RF adjustment unit 302 until the phase difference stabilizes within the target range. Simultaneously, the closed-loop control component 306 dynamically adjusts the RF power according to changes in plasma parameters to ensure the stability of plasma parameters. This achieves real-time, high-precision detection and closed-loop control of the phase of the two coil currents, effectively eliminating phase inconsistencies caused by differences in component parameters, temperature drift, and other factors, thereby ensuring the uniformity and stability of the plasma.

[0041] Specifically, the first current phase detection component 304 and the second current phase detection component 305 are Rogowski coil current detection circuits. A Rogowski coil is a hollow ring current sensor based on the principle of electromagnetic induction, which is particularly suitable for non-contact measurement of high-frequency, high-current signals.

[0042] Specifically, the dual-coil ICP current phase difference control device has two paths: the first path corresponds to the center coil and is connected in sequence to an arbitrary waveform generator, a 13.56MHz 3KW RF power amplifier, and an L-shaped impedance matching network, with the output connected to the center coil; the second path corresponds to the edge coil and is connected in sequence to an arbitrary waveform generator, a 13.56MHz 3KW RF power amplifier, and an impedance matching network, with the output independently connected to the edge coil; both excitation units share the same 10MHz temperature-controlled crystal oscillator as a reference clock, and the waveform type, frequency, power, and RF power output phase can be set separately.

[0043] Specifically, the three-coil ICP-controlled inductively coupled antenna system includes three independent inductor coils arranged coaxially: the center, the middle, and the edge. Each coil corresponds to an independent radio frequency excitation unit and a Rogowski coil current acquisition channel. The current phase synchronization and closed-loop control unit can independently set the target phase difference ΔφI1 between the center and the middle coil and the target phase difference ΔφI2 between the middle and the edge coil, thereby achieving third-order fine control of the radial distribution of plasma.

[0044] Specifically, the Rogowski coil is as follows: Figure 4 As shown, this is an integrating circuit with a single-supply Rogowski coil used to detect RF current. It includes operational amplifiers D10 and D11, resistors R10 to R17, and capacitors C10 to C13. Resistors R10 and R11 are connected to the two ends of the Rogowski coil to match the high input impedance of the Rogowski coil and the operational amplifiers, reducing signal reflection. Resistors R12 and R13 are of equal value to ensure the stability of the input circuit of operational amplifier D10 and provide common-mode rejection ratio. Capacitors C10 and C11 are connected in parallel across resistors R12 and R13 to form an RC low-pass filter, filtering out high-frequency noise in the input signal. Capacitors C10 and C11 are of equal value. Operational amplifier D10 is connected to DC blocking capacitor C12 at its output. Resistor R14 clamps the DC point of the input node of the integrator circuit at V_Ref, solving the problem of node potential fluctuation after DC blocking by capacitor C12. This resistor can be specially selected as 90K. R15 and capacitor C13 form a passive integrator circuit. Operational amplifier D11 is a non-inverting amplifier, which realizes the second-stage signal amplification and output drive. Resistors R16 and R17 determine the AC gain of the second-stage non-inverting amplifier.

[0045] Example 2 This invention provides a control method for an inductively coupled plasma device, based on a control system for an inductively coupled plasma device in Embodiment 1, which includes the following steps: Step S1: Maintain the background vacuum and pressure environment of the vacuum chamber through the vacuum chamber module 10; Step S2: Obtain the plasma parameters within the vacuum chamber module 10 through the plasma parameter diagnostic module 20; Step S3: Obtain the plasma parameters and the current phase of the inductor coil 106 through the radio frequency current phase control module 30; Step S4: The radio frequency current phase control module 30 generates a radio frequency control signal based on the plasma parameters; Step S5: Control the inductor coil 106 through the radio frequency control signal.

[0046] Specifically, steps S1-S5 include the following steps: Based on the process requirements to be processed, the target plasma parameters within the vacuum chamber module 10 are determined, including the target electron density, electron temperature, ion energy, and ion flux. Initial parameter matching: The current phase closed-loop control unit 303 calls the pre-stored current phase difference-plasma parameter mapping database according to the target plasma parameters to determine the initial radio frequency parameters corresponding to each inductor coil 106, including waveform type, frequency, power, and the 0°~360° continuously adjustable target current phase difference corresponding to each inductor coil 106. Chamber environment preparation: The vacuum chamber module 10 evacuates the chamber to a preset background vacuum, and the process gas is introduced through the gas inlet component 105 to control the chamber pressure to stabilize to the set value, thus completing the configuration of the process environment; Plasma ignition and closed-loop control: The RF excitation unit 301 outputs an RF voltage waveform according to the initial parameters. After being adjusted by the RF adjustment unit 302, the waveform is distributed and applied to the corresponding inductor coil 106. Plasma is generated in the vacuum chamber module 10 through inductive coupling. At the moment of plasma ignition, the current phase closed-loop control unit 303 is activated simultaneously to detect the phase difference between each group of coils. The closed-loop control component 306 controls the RF adjustment unit 302 to adjust the capacitance values ​​of the vacuum adjustable capacitors C1 and C2, thereby realizing closed-loop control of the current phase difference between the inductor coils 106. This compensates for the phase drift caused by impedance changes during ignition in real time and locks the current phase difference within the target range. Stable chamber environment: Through the action of gas inlet assembly 105 and vacuum pump 101, the chamber gas pressure is stabilized to the process set value again. During this process, the current phase difference is continuously maintained and the matching is adjusted by the L-type matching network in RF adjustment unit 302. Plasma parameter readjustment: The plasma parameter diagnostic module 20 monitors the plasma parameters within the vacuum chamber module 10 and feeds them back to the current phase closed-loop control unit 303; the control unit compares the real-time detected parameters with the target parameters. If there is a deviation in the plasma spatial distribution parameters, the target current phase difference in step S4 is adjusted first; if the phase difference adjustment cannot cover the target range, the RF power, excitation frequency, chamber pressure, and other parameters are adjusted as an auxiliary measure until the plasma parameters detected by the plasma parameter diagnostic module 20 are stable within the target range. Process execution and overall stability control: Once the plasma parameters reach the set target, the wafer enters the vacuum chamber module 10 for processing; during the process, current phase difference control and plasma parameter detection are continuously executed to ensure that the parameters are stable throughout the process until processing is completed.

[0047] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0048] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An inductively coupled plasma apparatus control system, characterized by, The system includes a vacuum chamber module (10), a plasma parameter diagnostic module (20), and a radio frequency current phase control module (30). Several inductor coils (106) are provided above the vacuum chamber module (10). The vacuum chamber module (10) is used to maintain the background vacuum and gas pressure environment of the chamber. The plasma parameter diagnostic module (20) is used to acquire the plasma parameters in the vacuum chamber module (10). The radio frequency current phase control module (30) is used to acquire the plasma parameters and the current phase of the inductor coils (106), and to send radio frequency control signals to control the inductor coils (106) according to the plasma parameters and the current phase.

2. The inductively coupled plasma apparatus control system of claim 1, wherein, The top of the vacuum chamber module (10) is a quartz top plate (104).

3. The inductively coupled plasma apparatus control system of claim 1, wherein, The vacuum chamber module (10) is also equipped with a vacuum pump (101), a worktable (102) and a gas inlet assembly (105). The vacuum pump (101) is located at the bottom of the vacuum chamber module (10), the worktable (102) is located above the bottom surface of the vacuum chamber module (10), and the gas inlet of the gas inlet assembly (105) is located at the top of the vacuum chamber module (10).

4. The control system for an inductively coupled plasma device according to claim 1, characterized in that, The number of groups of the plurality of inductors (106) is greater than or equal to two groups, and the plurality of inductors (106) are all three-dimensional planar spiral inductors wound in the same direction or planar spiral inductors wound in the same direction.

5. The control system for an inductively coupled plasma device according to claim 1, characterized in that, The plasma parameter diagnostic module (20) includes a spectrometer main control unit (201) and an optical fiber probe (202), and the optical fiber probe (202) is connected to the spectrometer main control unit (201) via optical fiber.

6. The control system for an inductively coupled plasma device according to claim 1, characterized in that, The radio frequency current phase control module (30) includes a radio frequency excitation unit (301), a radio frequency adjustment unit (302), and a current phase closed-loop control unit (303). The radio frequency excitation unit (301) is used to output a radio frequency voltage waveform. The radio frequency adjustment unit (302) is used to acquire the radio frequency voltage waveform and allocate the radio frequency voltage waveform into several radio frequency signals. The current phase closed-loop control unit (303) is used to adjust the several radio frequency signals according to the current phase and plasma parameters to obtain a radio frequency control signal and output the radio frequency control signal to the inductor coil (106).

7. The inductively coupled plasma device control system according to claim 6, characterized in that, The radio frequency conditioning unit (302) includes a power divider D1, which outputs two branches. Each branch is provided with two vacuum adjustable capacitors, and an L-type matching network is provided between the two vacuum adjustable capacitors on the same branch.

8. The control system for an inductively coupled plasma device according to claim 6, characterized in that, The current phase closed-loop control unit (303) includes a first current phase detection component (304) and a second current phase detection component (305), both of which are electrically connected to the closed-loop control component (306).

9. The control system for an inductively coupled plasma device according to claim 8, characterized in that, The first current phase detection component (304) and the second current phase detection component (305) are Rogowski coil current detection circuits.

10. A control method for an inductively coupled plasma device, based on the inductively coupled plasma device control system according to any one of claims 1-9, characterized in that, It includes the following steps: Step S1: Maintain the background vacuum and pressure environment of the vacuum chamber through the vacuum chamber module (10); Step S2: Obtain the plasma parameters within the vacuum chamber module (10) through the plasma parameter diagnostic module (20); Step S3: Obtain the plasma parameters and the current phase of the inductor coil (106) through the radio frequency current phase control module (30); Step S4: The radio frequency current phase control module (30) generates a radio frequency control signal based on the plasma parameters; Step S5: Control the inductor coil (106) through the radio frequency control signal.

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