Plasma processing apparatus and automatic uniformity control method

Abstract

The application relates to a plasma processing device and an automatic uniformity regulating method. The device comprises a plasma chamber, a first electrode and a second electrode oppositely arranged in the chamber, and a radio frequency feeding device for transmitting a radio frequency current to the second electrode; a sensing layer containing diamond color centers is formed on the surface of the radio frequency feeding device in the chamber; by exciting the color centers and collecting the fluorescent signal, the real-time magnetic field distribution of the surface area of the radio frequency feeding device is determined, and a regulating signal is generated based on the comparison result with a target magnetic field distribution, so that the radio frequency current is regulated in a closed loop control mode, and the magnetic field distribution of the wafer carrying area tends to approach the target magnetic field distribution. The application can realize real-time measurement of three-dimensional vector magnetic field with high spatial resolution and millisecond-level closed loop control in situ, so that the uniformity of plasma processing is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of plasma processing equipment technology, and in particular to plasma processing equipment and an automatic uniformity control method. Background Technology

[0002] In semiconductor manufacturing, capacitively coupled plasma (CCP) processing equipment is widely used in wafer fabrication. Radio frequency (RF) current is transmitted to the lower electrode via a matching network and RF feed device, generating a plasma sheath on the wafer surface. The shape of the sheath (radial profile, angular uniformity) directly affects the uniformity of the processing rate, thus determining the chip yield.

[0003] Existing sensors for monitoring plasma uniformity are all placed outside the radio frequency feed device in the form of discrete probes, which cannot directly contact the current transmission surface, resulting in signal attenuation and loss of spatial resolution. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a plasma processing device and an automatic uniformity control method, which can realize in-situ, high spatial resolution three-dimensional vector magnetic field real-time measurement and millisecond-level closed-loop control, thereby significantly improving the uniformity of plasma processing.

[0005] The technical solution adopted by this invention to solve its technical problem is: to provide a plasma processing device, comprising:

[0006] Plasma chamber;

[0007] The first and second electrodes are disposed opposite to each other within the plasma chamber;

[0008] A radio frequency (RF) feed device is used to transmit RF current to a second electrode. The RF feed device is placed on the surface of a portion of the plasma chamber and a sensing layer is formed thereon. The sensing layer includes a diamond film, and the color centers of the diamond film generate a fluorescence signal when excited. The RF feed device is configured such that the transmitted RF current is adjusted according to the fluorescence signal, so that the magnetic field distribution on the surface region of the RF feed device approaches the target magnetic field distribution. The surface region of the RF feed device includes a wafer carrier region.

[0009] Furthermore, the diamond film comprises an array of multiple sensing pixels, each of which comprises multiple color centers with different orientations.

[0010] Furthermore, each of the said sensing pixels has a size of 1μm to 50μm.

[0011] Furthermore, the diamond film has a thickness of 10 nm to 10 μm and a color center concentration of 1 ppb to 100 ppm.

[0012] Furthermore, it also includes:

[0013] A microwave unit is used to drive the color center spin transition of the diamond film;

[0014] An optical unit is used to excite the color centers of the diamond film and collect the generated fluorescence signal;

[0015] The processing unit is configured to determine the real-time magnetic field distribution of the surface region of the radio frequency feeding device based on the fluorescence signal, and generate an adjustment signal based on the comparison result between the real-time magnetic field distribution and the target magnetic field distribution.

[0016] A radio frequency generator or electrode power distribution network is used to adjust the radio frequency current in a closed-loop control loop in response to the adjustment signal, so that the magnetic field distribution on the surface area of ​​the radio frequency feed device approaches the target magnetic field distribution.

[0017] Furthermore, the microwave unit includes a microwave generator and a microwave antenna, with the antenna arranged adjacent to the sensing layer.

[0018] The present invention also provides an automatic plasma uniformity control method, applied to the plasma etching apparatus described above, comprising the following steps:

[0019] A radio frequency current is fed in to excite plasma between the first electrode and the second electrode;

[0020] The color centers of the diamond film are excited, and the real-time magnetic field distribution on the surface region of the radio frequency feeding device is calculated based on the collected fluorescence signal.

[0021] The real-time magnetic field distribution is compared with the target magnetic field distribution to extract spatial distribution feature deviation.

[0022] Based on the spatial distribution characteristic deviation, an adjustment signal is generated to adjust the radio frequency current, so that the real-time magnetic field distribution approaches the target magnetic field distribution.

[0023] Furthermore, the diamond film comprises an array of multiple sensing pixels, each of which includes multiple color centers with different orientations. The calculation of the real-time magnetic field distribution on the surface region of the radio frequency feeding device based on the collected fluorescence signal includes the following steps:

[0024] Obtain the ODMR spectra of the sensing pixel on different directional axes;

[0025] The Zeeman splitting amount on each directional axis is extracted from the ODMR spectrum of the sensing pixel, and the projected magnetic field components on each directional axis are determined based on the Zeeman splitting amount.

[0026] The three-dimensional magnetic field vector at each of the sensing pixels is reconstructed based on the projected magnetic field components.

[0027] The three-dimensional magnetic field vectors of all the sensing pixels are combined according to their spatial positions to form the real-time magnetic field distribution.

[0028] Furthermore, it also includes:

[0029] Extract the drift of the zero-field splitting parameter from the ODMR spectrum;

[0030] Based on the mapping relationship between the zero-field splitting parameter and temperature, the real-time temperature at the corresponding sensing pixel is determined.

[0031] Based on the determined real-time temperature, the three-dimensional magnetic field vector at the corresponding sensing pixel is corrected.

[0032] Furthermore, it also includes:

[0033] Based on the ODMR spectrum, the linewidth of the ODMR resonance peak of each sensing pixel is extracted and compared with the intrinsic linewidth of the stress-free diamond color center to determine the stress state at the corresponding sensing pixel.

[0034] Beneficial effects

[0035] By adopting the above-mentioned technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0036] This invention achieves atomic-level contact between the sensing layer and the current transmission surface by directly forming the sensing layer on the surface of the RF feed device, eliminating the need for discrete probes, optical fibers, or displacement platforms. This structure fundamentally eliminates the physical gap between the sensor and the measured surface, avoiding mechanical vibration, alignment errors, and maintenance costs, and significantly improving the long-term reliability of the system under industrial vibration and temperature fluctuation environments.

[0037] This invention patterns the sensing layer into an array of multiple sensing pixels, each containing multiple NV color centers with different orientations. The projected magnetic field components are determined by measuring the Zeeman splitting along each NV axis. Then, based on the known geometric relationship between the NV axis directions and the diamond lattice coordinate system, a three-dimensional magnetic field vector at each pixel is reconstructed. Compared to existing technologies that only provide scalar or unidirectional magnetic field information, the three-dimensional vector magnetic field more completely reflects the spatial distribution of current paths and plasma loads, providing a richer information foundation for precise control.

[0038] This invention, while measuring the magnetic field, extracts the drift of the zero-field splitting parameter from the ODMR spectrum to determine the real-time temperature of the sensing layer. This temperature is then used to correct the magnetic field measurement in real time, eliminating the impact of temperature drift on measurement accuracy. Furthermore, the stress state of the sensing layer can be determined by extracting the linewidth of the ODMR resonance peak and comparing it with the intrinsic linewidth of the stress-free diamond NV color center, providing a basis for monitoring the equipment's health status. Temperature and stress sensing can be achieved using the same hardware system, eliminating the need for additional sensors.

[0039] This invention uses the magnetic field vector distribution as feedback to extract spatial distribution characteristic deviations. Based on these deviations, an adjustment signal is generated to automatically adjust the frequency, power, phase, or electrode power distribution ratio of the radio frequency current, making the real-time magnetic field distribution approximate the target magnetic field distribution. This closed-loop control method requires no manual intervention, significantly shortening the process development cycle and improving the consistency of mass production. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the system structure according to the first embodiment of the present invention;

[0041] Figure 2 This is a partial enlarged view of the NV color center array on the surface of the power rod according to the first embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the three-dimensional magnetic field vector of the NV color center array on the surface of the power rod according to the first embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of the ODMR spectrum of the first embodiment of the present invention;

[0044] Figure 5 This is a flowchart illustrating the second embodiment of the present invention;

[0045] Figure 6 This is a closed-loop magnetic field distribution diagram before and after automatic control according to the second embodiment of the present invention. Detailed Implementation

[0046] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0047] The first embodiment of the present invention relates to a plasma processing apparatus, comprising:

[0048] Plasma chamber;

[0049] The first and second electrodes are disposed opposite to each other within the plasma chamber;

[0050] A radio frequency (RF) feed device is used to transmit RF current to the second electrode. A sensing layer is formed on the surface of the inner part of the plasma chamber of the RF feed device. The sensing layer includes a diamond film.

[0051] An optical unit is used to excite the color centers of the diamond film and collect the generated fluorescence signal;

[0052] Microwave unit used to drive the color center spin transition of diamond film;

[0053] The adjustment module is used to adjust the radio frequency current according to the fluorescence signal so that the magnetic field distribution on the surface area of ​​the radio frequency feeding device approaches the target magnetic field distribution.

[0054] The wafer to be etched is placed on the second electrode, and the surface area of ​​the radio frequency feeding device includes the wafer carrier area.

[0055] The adjustment module can be implemented using a processing unit and an RF generator or an electrode power distribution network, wherein:

[0056] The processing unit is used to determine the real-time magnetic field distribution on the surface region of the radio frequency feeding device based on the fluorescence signal, and to generate an adjustment signal based on the comparison between the real-time magnetic field distribution and the target magnetic field distribution.

[0057] A radio frequency generator or electrode power distribution network is used to adjust the radio frequency current in a closed-loop control loop in response to a modulation signal, so that the magnetic field distribution on the surface area of ​​the radio frequency feed device approaches the target magnetic field distribution.

[0058] Figure 1 The overall structure of a real-time closed-loop control system for a radio frequency magnetic field in a plasma processing chamber, provided by an embodiment of the present invention, is shown. This embodiment uses a power rod as a radio frequency feeding device.

[0059] The system includes a plasma chamber 100, in which a first electrode (upper electrode) 101 and a second electrode (lower electrode) 102 are disposed opposite each other, and a wafer 103 to be processed is placed on the lower electrode 102. The lower electrode 102 is connected to a matching network 104 and a radio frequency generator 180 via a power rod 105.

[0060] The power rod 105 is used to transmit radio frequency (RF) current, feeding RF power from the matching network 104 to the lower electrode 102 to excite and maintain plasma between the first electrode 101 and the second electrode 102. The power rod 105 is both a physical transmission channel for RF current and its surface serves as a substrate for the in-situ sensing layer.

[0061] More specifically, the in-situ sensing layer 110 is formed directly on at least a portion of the surface of the power rod 105. This in-situ sensing layer 110 comprises a diamond film with multiple nitrogen-vacancy (NV) color centers and is in atomic-level contact with the surface of the power rod 105. The sensing layer 110 does not contain any fiber optic probes or discrete scanning mechanisms, and the sensing area covers the circumferential and / or axial directions of the power rod 105, enabling omnidirectional sensing of the magnetic field distribution on the power rod surface.

[0062] The system also includes an optical excitation and detection system, a microwave control system, a signal processing unit 160, a comparator 170, and an actuator.

[0063] An optical excitation and detection system is used to excite the NV color centers in the sensing layer 110 and collect the generated fluorescence signals. Specifically, the optical excitation and detection system includes a laser 120 (such as a 532nm laser), a beam shaper 121, a fluorescence collecting mirror 140, a long-pass filter 141, and a detector 150. The excitation light emitted by the laser 120 illuminates the sensing layer 110 through the beam shaper 121, exciting the NV color centers to emit fluorescence; the fluorescence passes through the fluorescence collecting mirror 140 and the filter 141 and then enters the detector 150, where it is converted into an electrical signal.

[0064] A microwave control system is used to drive the spin transitions of the NV color center. The microwave control system includes a microwave generator 130 and a microwave antenna 131, which is arranged adjacent to the sensing layer 110 to ensure that the microwave field effectively acts on the sensing layer.

[0065] The signal processing unit 160 is configured to receive fluorescence signals from the optical excitation and detection system in real time and calculate at least one magnetic field component at each NV color center location. The signal processing unit 160 can employ continuous wave lock detection, heterodyne detection, or neural network regression methods, without requiring a complete scan of the microwave frequency, thereby achieving a magnetic field update rate in the microsecond to millisecond range.

[0066] Comparator 170 is configured to compare the calculated magnetic field distribution with a preset target magnetic field distribution and generate an adjustment signal. Specifically, comparator 170 may extract at least one feature of the magnetic field distribution, namely circumferential uniformity, axial gradient, or harmonic content, and compare it with the target feature.

[0067] The RF generator 180 or the electrode power distribution network is configured to adjust at least one property of the RF current in a closed-loop control loop in response to an adjustment signal, so that the magnetic field distribution approximates a target magnetic field distribution. The electrode power distribution network may include segmented lower electrodes 102, each segment of which can independently adjust its RF power, achieving independent angular control.

[0068] Figure 2A partially enlarged view of the sensing layer on the surface of the power rod is shown. The in-situ sensing layer 110 is formed directly on the surface of the power rod 105 by chemical vapor deposition (CVD) or ion implantation. The thickness of the sensing layer is 10 nm to 10 μm, preferably 2 μm; the NV color center concentration (atomic ratio) is 1 ppb to 100 ppm.

[0069] The sensing layer 110 is patterned into multiple independently addressable pixels, forming a two-dimensional array. Each pixel has a size of 1 μm to 50 μm, and in the embodiment shown in the attached figure, it is 5 μm × 5 μm, with a spacing between adjacent pixels of 5 μm to 10 μm. This array can be a 16 × 16 array, but in practice, it can be any M × N array. Each pixel can independently measure the magnetic field at its location, thereby achieving high spatial resolution magnetic field distribution sensing.

[0070] like Figure 2 As shown in the right figure, each sensing pixel contains multiple NV color centers with different orientations. In a diamond lattice, the NV color centers have four equivalent crystal orientations (i.e., NV axis directions), along the <1,1,1>, <1,-1,-1>, <-1,1,-1>, and <-1,-1,1> directions, respectively. These four NV axes diverge from the center point to the four vertices of the regular tetrahedron. Figure 3 As shown, since the projections of the external magnetic field by NV color centers with different orientations are different, a complete three-dimensional magnetic field vector can be reconstructed by measuring the magnetic field projection components along each NV axis. This structure realizes the dual functions of spatial resolution measurement and vector reconstruction, demonstrating the in-situ integration advantages of this invention, which eliminates the need for discrete probes and scanning mechanisms.

[0071] The detection mechanism of magnetic fields will be further explained below:

[0072] 1. Energy level structure and optical properties of NV color centers

[0073] An NV color center is a point defect in a diamond lattice where a nitrogen atom replaces a carbon atom and forms an adjacent vacancy; it possesses C3v symmetry. Its electronic ground state is ³A2, and its excited state is ³E, both being spin triplet states (S=1). The three spin sublevels are m_s = 0, ±1, and ±1, respectively.

[0074] In the absence of an external magnetic field, there is a zero-field split between m_s = 0 and m_s = ±1, with a value of D ≈ 2.87 GHz, due to spin-spin interactions. Therefore, the ground state energy level structure is as follows: the m_s = 0 level is the lowest, and the m_s = ±1 level is degenerate and higher than D·h (where h is Planck's constant).

[0075] When excited by a 532 nm green laser, the NV color center absorbs photons and transitions to the excited state. Upon returning to the ground state, the radiative transition probability of the m_s = 0 state is much higher than that of the m_s = ±1 state. The m_s = ±1 state has approximately a 30% probability of nonradiative relaxation to the m_s = 0 ground state via intersystem crossing (ISC) through a metastable singlet state (¹A), resulting in a decrease in fluorescence intensity. This property allows the spin state to be detected by measuring fluorescence intensity: fluorescence is strong when the electron population is at m_s = 0, and weak when the population is at m_s = ±1.

[0076] 2. Microwave-driven spin resonance and ODMR principle

[0077] Figure 4 The physical principles of magnetic field measurement are illustrated using ODMR spectral diagrams. Figure 4 As shown in the left figure, when the external magnetic field B=0, there is only a zero-field split between the ground state m_s=0 and m_s=±1 energy levels of the NV color center, D≈2.87 GHz.

[0078] A microwave field with a frequency of approximately 2.87 GHz is applied between the ground states m_s = 0 and m_s = ±1. When the microwave frequency is exactly equal to the energy level difference, a magnetic dipole transition is induced, causing the electron spin to flip from m_s = 0 to m_s = ±1. Since the fluorescence of the m_s = ±1 state is weak, the observed fluorescence intensity decreases at this point, and a single fluorescence trough (Lorentz-type trough) is observed at f = D.

[0079] This phenomenon is called optically detected magnetic resonance (ODMR). By scanning microwave frequencies and recording fluorescence intensity, ODMR spectra can be obtained—fluorescence troughs (Lorentz-type troughs) appear at the resonance frequencies.

[0080] 3. Magnetic field measurement: Zeeman splitting and resonance peak spacing

[0081] like Figure 4 As shown in the right figure, when the external magnetic field B > 0, due to the Zeeman effect, the m_s = ±1 energy level splits: the m_s = +1 energy level rises, and the m_s = -1 energy level falls (or vice versa, depending on the direction of the magnetic field). The splitting amount ΔE = h·γ·B || Where γ = gμ_B / h ≈ 28.0 GHz / T is the electron gyromagnetic ratio, and B || = B·n is the projected component of the magnetic field along the NV axis (i.e., the direction from the nitrogen atom to the vacancy, denoted as n).

[0082] At this point, the original single resonance peak splits into two peaks, with resonance frequencies of:

[0083]

[0084] The frequency difference between the two peaks is:

[0085]

[0086] Therefore, by measuring the center frequency difference between the two resonance peaks in the ODMR spectrum, the magnetic field component along the NV axis can be directly calculated:

[0087]

[0088] The measured value B || It is independent of zero-field splitting D, and therefore is not affected by D drift caused by temperature changes (self-compensation characteristic).

[0089] 4. Three-dimensional vector magnetic field reconstruction: four-axis NV orientation

[0090] In a diamond lattice, the axial direction of the NV color center has four equivalent orientations, along <1,1,1>, <1,-1,-1>, and so on.

[0091] Crystal directions <-1,1,-1> and <-1,-1,1>. Let the unit vectors of the four crystal directions be:

[0092]

[0093]

[0094]

[0095]

[0096] The projection of the external magnetic field onto the NV color center differs for each orientation. The projection values ​​B for the four orientations are measured separately. || 1, B || 2,B || 3, B || 4. The system of linear equations is obtained:

[0097]

[0098] Solving this system of equations yields the three components of the magnetic field vector:

[0099]

[0100] Therefore, as long as the resonant frequencies of four different oriented NV color centers are obtained simultaneously at each pixel (or the B color centers are directly measured), it is possible to achieve this. || i), and the three-dimensional magnetic field vector (Bx, By, Bz) at that point can be completely determined.

[0101] 5. Additional measurements of temperature and stress

[0102] By utilizing the known linear relationship between the zero-field splitting of the NV color center and temperature, real-time temperature correction can be performed on the measured magnetic field values.

[0103] Zero-field splitting D varies linearly with temperature:

[0104]

[0105] Where D0 = 2.87 GHz (T0 = 300 K), α ≈ -74 kHz / K. The real-time temperature of the sensing layer can be deduced by measuring the average frequency (i.e., the D value) of the double peaks in the ODMR spectrum.

[0106]

[0107] This allows for real-time temperature correction of the magnetic field measurements, eliminating the impact of temperature drift on measurement accuracy.

[0108] Furthermore, lattice strain broadens the ODMR spectral lines (increases the Lorentz linewidth). By monitoring the linewidth Δν, the stress state inside the diamond film can be assessed, which can be used for monitoring the mechanical health of power rods.

[0109] 6. Rapid Measurement: From Frequency Sweep to Lock-on Detection

[0110] Traditional ODMR requires full-band scanning (e.g., 2.7–3.1 GHz, with a step size of 1 MHz), taking hundreds of milliseconds, which is unsuitable for real-time control. This implementation employs the following acceleration techniques:

[0111] Method 1: Frequency Modulation Lock Detection The microwave frequency f(t) = f0 Modulation is applied near the resonance peak, and the amplitude of the first harmonic component of the fluorescence is proportional to the detuning amount f0 - f_res. The error signal is demodulated by a lock-in amplifier, driving a microwave source to track the resonance peak in real time. This method achieves a time constant as low as 10 μs and a magnetic field update rate ≥10 kHz.

[0112] Method 2: Heterodyne Probe. Simultaneously applying two microwave frequencies, f1 = f_res - Δ and f2 = f_res + Δ (Δ is less than the resonant linewidth), will generate a beat frequency signal with a frequency of 2Δ in the fluorescence response. By measuring the phase or amplitude of the beat frequency signal, f_res can be quickly calculated, and thus B can be obtained. || .

[0113] Method 3: Direct regression using neural networks to calculate fluorescence intensities I(t1), I(t2), …, at multiple time points. The input is a lightweight neural network, which directly outputs (Bx, By, Bz). This method does not require explicit fitting of the Lorentz peak or lock-in demodulation, and the computational delay can be less than 1 μs.

[0114] Through the aforementioned rapid measurement technology, this invention achieves a frame rate ≥ 1 kHz, meeting the real-time control requirements of plasma processes.

[0115] The second embodiment of the present invention relates to an automatic plasma uniformity control method, applied to the aforementioned plasma etching apparatus, comprising the following steps:

[0116] A radio frequency current is fed in to excite plasma between the first electrode and the second electrode;

[0117] The color centers of the diamond film are excited, and the real-time magnetic field distribution on the surface region of the radio frequency feeding device is calculated based on the collected fluorescence signal.

[0118] The real-time magnetic field distribution is compared with the target magnetic field distribution to extract spatial distribution feature deviation.

[0119] Based on the spatial distribution characteristic deviation, an adjustment signal is generated to adjust the radio frequency current, so that the real-time magnetic field distribution approaches the target magnetic field distribution.

[0120] Figure 5 The complete execution logic of the closed-loop control method of this invention is illustrated in the form of a standard flowchart, including the following key steps:

[0121] Step 1: System Calibration

[0122] Before the process, the zero-field resonance frequency is recorded as a temperature reference, the background magnetic field is measured for subsequent subtraction, and a response matrix of the magnetic field distribution characteristics relative to the adjustment amount is established.

[0123] Step 2: Real-time data acquisition

[0124] During the plasma processing, an RF current is fed in to excite plasma between the first and second electrodes; at the same time, fluorescence signals of multiple pixels on the in-situ sensing layer 110 are acquired in real time at a preset frame rate (e.g., ≥1 kHz).

[0125] Step 3: Fast solution and feature extraction

[0126] The three-dimensional magnetic field vector of each pixel is calculated from the fluorescence signal. Specifically, the resonance frequencies of four NV color centers with different crystal orientations are measured, and the three components of the magnetic field (Bx, By, Bz) are solved using a system of linear equations. The magnetic field vectors of each pixel are combined according to their spatial positions to form a real-time magnetic field distribution.

[0127] Spatial inhomogeneity features are extracted from the magnetic field distribution. These features include at least one of circumferential homogeneity, radial gradient, and harmonic content.

[0128] Step 4: Deviation Judgment

[0129] The extracted features are compared with preset target features. If the deviation is less than a preset threshold, the current parameters are maintained and monitoring continues; if the deviation exceeds the threshold, the adjustment step is initiated.

[0130] Step 5: Calculation and Execution of Adjustment Amount

[0131] Using a pre-calibrated response matrix or machine learning model, the feature deviation is converted into a regulation value, generating a regulation signal. The regulation signal is sent to the RF generator or electrode power distribution network via a feedback interface. RF parameter regulation includes changing at least one of the RF signal's frequency, power, phase, or duty cycle. Electrode power distribution regulation includes independently changing the RF power of different angular segments of the lower electrode.

[0132] Step 6: Iterative Convergence

[0133] Repeat steps two through six until the deviation meets the requirements, forming a closed loop of continuous monitoring and iterative adjustment.

[0134] like Figure 6 As shown, the magnetic field distribution before adjustment was circumferentially uneven (strong magnetic field on one side, weak magnetic field on the other side), which manifested as a circumferential difference in etching rate. After adjustment through feedback control, the magnetic field distribution became a concentric, uniform distribution.

[0135] The following specific embodiment further illustrates the implementation of the present invention.

[0136] This embodiment integrates the aforementioned sensing and control system on a 300 mm CCP etching apparatus. The power rod has a diameter of 25 mm, a length of 300 mm, and is made of oxygen-free copper. The RF generator is 60 MHz / 1000 W, with an adjustable frequency range of ±5%. The lower electrode is configured with a segmented power supply structure, allowing independent adjustment of the RF power in each segment.

[0137] Sensing layer fabrication:

[0138] Polish the surface of the power rod to Ra < 0.1 μm and clean it.

[0139] Diamond films were deposited by microwave plasma CVD with a CH4 / H2 ratio of 2%, a pressure of 30 Torr, a temperature of 800℃, a time of 8 hours, and a film thickness of 2 μm.

[0140] Ion implantation was performed at an energy of 14 keV and a dose of 1 × 10¹³ cm⁻² (N⁺). Implantation was followed by vacuum annealing at 850°C for 2 hours to form NV centers. The concentration of NV centers was approximately 1 ppm.

[0141] A 20×20 pixel array is defined by photolithography and oxygen plasma etching, with a pixel size of 10 μm×10 μm and a spacing of 15 μm, forming an independently addressable two-dimensional array.

[0142] A vapor-deposited coplanar waveguide microwave antenna (Au, 200 nm thick, 50 μm linewidth, 50 μm spacing) is arranged adjacent to the sensing layer.

[0143] Optical and Detection Systems:

[0144] The laser is a 532 nm, 200 mW continuous wave, expanded by a cylindrical lens into a 5 mm × 5 mm spot covering the array area. Fluorescence collection uses a 50× objective lens (NA=0.8), passes through a 650 nm long-pass filter, and then enters a 20 × 20 SPAD array detector, with independent readout per pixel at a frame rate of 2 kHz. The microwave frequency is set to 2.87 GHz ± 50 MHz, employing a continuous wave lock-in detection method (modulation amplitude ± 10 MHz, modulation frequency 100 kHz). This eliminates the need for a complete microwave frequency scan, directly demodulating the output resonant peak shift to achieve a millisecond-level magnetic field update rate.

[0145] Temperature and stress are sensed simultaneously:

[0146] While calculating the magnetic field, the signal processing unit measures the average frequency of the double peaks in the ODMR spectrum and uses the known linear relationship between zero-field splitting and temperature (approximately -74 kHz / K) to perform real-time temperature correction on the magnetic field measurement. Simultaneously, by calculating the fluorescence linewidth of each pixel and comparing it with the intrinsic linewidth of the stress-free diamond NV color center, the stress distribution within the diamond film is evaluated for power rod health monitoring.

[0147] Control process and effects:

[0148] Initially, the circumferential non-uniformity of the magnetic field was 8.7%, and the threshold was set to 5%. A comparator extracted the circumferential uniformity characteristics of the magnetic field distribution. After comparing it with the target characteristics, the deviation exceeded the threshold. The adjustment amount was calculated using a pre-calibrated response matrix: a 1% increase in power in the 90° direction resulted in a 0.28% increase in the magnetic field in that direction; a 1% decrease in power in the 270° direction resulted in a 0.31% decrease in the magnetic field in that direction. In the first adjustment, power was increased by 12% in the 90° direction and decreased by 8% in the 270° direction, while remaining unchanged in other directions. After adjustment, the circumferential non-uniformity decreased to 3.2%. A second fine adjustment of ±3% reduced the circumferential non-uniformity to 2.1%, meeting the requirements. The total closed-loop time was approximately 27 ms (3 iterations × (5 ms acquisition + 2 ms calculation + 2 ms response) ≈ 27 ms.

[0149] In the SiO2 etching process, the non-uniformity of etching rate at the wafer edge (radius 145-150 mm) was improved from 12% (1σ) to 2.5%, and the difference at the center edge was reduced from 8% to 1.5%.

[0150] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A plasma processing device, characterized in that, include: Plasma chamber; The first and second electrodes are disposed opposite to each other within the plasma chamber; A radio frequency (RF) feed device is used to transmit RF current to the second electrode. A sensing layer is formed on the surface of a portion of the RF feed device within the plasma chamber. The sensing layer comprises a diamond film, and the color centers of the diamond film generate a fluorescence signal upon excitation. The RF feed device is configured such that… The transmitted radio frequency current is adjusted according to the fluorescence signal so that the magnetic field distribution on the surface region of the radio frequency feeding device approaches the target magnetic field distribution; wherein, the surface region of the radio frequency feeding device includes a wafer carrier region.

2. The plasma etching apparatus according to claim 1, characterized in that, The diamond film comprises an array of multiple sensing pixels, each of which includes multiple color centers with different orientations.

3. The plasma etching apparatus according to claim 2, characterized in that, Each of the sensor pixels has a size ranging from 1 μm to 50 μm.

4. The plasma etching apparatus according to claim 1, characterized in that, The diamond film has a thickness of 10 nm to 10 μm and a color center concentration of 1 ppb to 100 ppm.

5. The plasma etching apparatus according to claim 1, characterized in that, Also includes: A microwave unit is used to drive the color center spin transition of the diamond film; An optical unit is used to excite the color centers of the diamond film and collect the generated fluorescence signal; The processing unit is configured to determine the real-time magnetic field distribution of the surface region of the radio frequency feeding device based on the fluorescence signal, and generate an adjustment signal based on the comparison result between the real-time magnetic field distribution and the target magnetic field distribution. A radio frequency generator or electrode power distribution network is used to adjust the radio frequency current in a closed-loop control loop in response to the adjustment signal, so that the magnetic field distribution on the surface area of ​​the radio frequency feed device approaches the target magnetic field distribution.

6. The plasma etching apparatus according to claim 5, characterized in that, The microwave unit includes a microwave generator and a microwave antenna, with the antenna arranged adjacent to the sensing layer.

7. An automatic method for controlling plasma uniformity, characterized in that, The method applied to the plasma etching apparatus as described in any one of claims 1 to 6 includes the following steps: A radio frequency current is fed in to excite plasma between the first electrode and the second electrode; The color centers of the diamond film are excited, and the real-time magnetic field distribution on the surface region of the radio frequency feeding device is calculated based on the collected fluorescence signal. The real-time magnetic field distribution is compared with the target magnetic field distribution to extract spatial distribution feature deviation. Based on the spatial distribution characteristic deviation, an adjustment signal is generated to adjust the radio frequency current, so that the real-time magnetic field distribution approaches the target magnetic field distribution.

8. The automatic control method according to claim 7, characterized in that, The diamond film comprises an array of multiple sensing pixels, each of which includes multiple color centers with different orientations. The calculation of the real-time magnetic field distribution on the surface region of the radio frequency feeding device based on the acquired fluorescence signal includes the following steps: Obtain the ODMR spectra of the sensing pixel on different directional axes; The Zeeman splitting amount on each directional axis is extracted from the ODMR spectrum of the sensing pixel, and the projected magnetic field components on each directional axis are determined based on the Zeeman splitting amount. The three-dimensional magnetic field vector at each of the sensing pixels is reconstructed based on the projected magnetic field components. The three-dimensional magnetic field vectors of all the sensing pixels are combined according to their spatial positions to form the real-time magnetic field distribution.

9. The automatic control method according to claim 8, characterized in that, Also includes: Extract the drift of the zero-field splitting parameter from the ODMR spectrum; Based on the mapping relationship between the zero-field splitting parameter and temperature, the real-time temperature at the corresponding sensing pixel is determined. Based on the determined real-time temperature, the three-dimensional magnetic field vector at the corresponding sensing pixel is corrected.

10. The automatic control method according to claim 8, characterized in that, Also includes: Based on the ODMR spectrum, the linewidth of the ODMR resonance peak of each sensing pixel is extracted and compared with the intrinsic linewidth of the stress-free diamond color center to determine the stress state at the corresponding sensing pixel.

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