A dry etching control method and device based on deep feedback

Abstract

The application discloses a dry etching control method and equipment based on depth feedback, constructs a state space model of a dry etching process, introduces an extended Kalman filter, fuses a depth measurement signal and an optical emission spectrum signal, and outputs optimal estimated values of etching depth and etching rate in real time during the etching process, and dynamically calculates first and second depth threshold values based on the optimal estimated values, so that the real-time depth threshold values drive accurate switching between a main etching stage, an over-etching stage and a charge releasing stage, and the electromagnetic coil array and the movable shielding plate are differentially configured in the stages, so that different stages correspond to different magnetic field distributions and shielding plate opening degrees, and the technical problem that the etching success rate is low due to the contradiction between charge accumulation and stage requirements in the high aspect ratio etching process is effectively solved, and the etching success rate of the high aspect ratio structure is improved.

Description

Technical Field

[0001] This invention relates to dry etching technology, and more particularly to a dry etching control method and apparatus based on depth feedback. Background Technology

[0002] Dry etching is a core process in semiconductor and display panel manufacturing. As device feature sizes continue to shrink, dry etching of high aspect ratio structures (aspect ratio greater than 30:1, such as 3D NAND channel vias and TSV through-silicon vias) has become a bottleneck for mass production. The mass production requirements of large-size substrates (2200mm × 2500mm) of G8.5 and above further place higher demands on the uniformity of the etched surface.

[0003] High aspect ratio etching faces two major coupled challenges: first, the charge accumulation effect, where the time difference between electron and ion arrival leads to the accumulation of positive charge at the bottom of the trench, causing defects such as arc discharge and etching stoppage; second, the different stage requirements throughout the etching process, with high energy needed in the initial stage to ensure rate and anisotropy, energy reduction needed in the middle stage to prevent over-etching and improve uniformity, and effective release of accumulated charge needed in the final stage. The requirements for parameters such as ion energy, plasma density, magnetic field distribution, and bias power at different stages are mutually restrictive.

[0004] Existing patent documents (such as CN102024669A) disclose a scheme that sequentially performs the main etching process, over-etching process, and charge release process, and inserts a transition process between steps to reduce reflected power. This scheme adjusts the RF source power and bias power, and its stage switching is based on a preset step sequence; charge release is the natural dissipation after power reduction. Some existing schemes achieve stage switching by adjusting the RF bias power or gas composition, with the switching threshold pre-calibrated using offline data. For large-size substrates of G8.5 and above, related control methods mainly affect power and gas parameters, with limited ability to control the difference in plasma distribution between the center and edges. This results in a low success rate for high aspect ratio etching, becoming a key bottleneck restricting the mass production of 3D NAND, TSV packaging, and large-size panels. Summary of the Invention

[0005] This invention provides a dry etching control method and device based on depth feedback, which can sense the etching status in real time, dynamically adjust the stage switching threshold, and perform three-stage differentiated configuration of the magnetic shielding system. This solves the technical problem of low etching success rate caused by the coupling of charge accumulation effect and staged requirement differences during the dry etching of high aspect ratio structures, and improves the etching success rate of high aspect ratio structures.

[0006] In a first aspect, the present invention provides a dry etching control method based on depth feedback, comprising: Acquire real-time monitoring data of the etching process, wherein the real-time monitoring data includes at least a depth measurement signal characterizing the etching depth and an optical emission spectrum signal characterizing the etching rate; A state-space model of the dry etching process is constructed. The real-time monitoring data is fused using an extended Kalman filter to perform real-time optimal estimation of the etching depth and etching rate, thus obtaining the optimal estimate of the current etching depth. And the optimal estimate of the current etching rate ; The first depth threshold is dynamically calculated based on the optimal estimate. Second depth threshold ; according to and , Comparison result execution phase switching: when During the main etching phase, when During the etching phase, when The charge release phase is executed at that time; For the main etching stage, the over-etching stage, and the charge release stage, the electromagnetic coil array and the movable shield are configured differently so that different magnetic field distributions and shield openings correspond to different stages.

[0007] Optionally, the electromagnetic coil array is coaxially arranged with at least three layers of independently controllable electromagnetic coil groups around the reaction chamber. Each layer of electromagnetic coil group includes four independently controlled sub-coils corresponding to the four quadrants of the chamber. The differentiated configuration of the electromagnetic coil array at each stage includes: During the main etching stage, the current of the electromagnetic coil group located in the middle of the chamber is set to the maximum value, and the current of other electromagnetic coil groups is configured according to the preset ratio of the maximum value to form a strong gradient magnetic field, which vertically focuses the plasma onto the substrate surface. During the over-etching stage, the current of the electromagnetic coil group located in the middle of the chamber is gradually reduced from its maximum value to be equal to that of other electromagnetic coil groups, thereby weakening the magnetic field focusing and making the plasma distribution more uniform. During the charge release phase, the electromagnetic coil array is switched to pulse mode to actively neutralize the positive charge accumulated at the bottom of the trench.

[0008] Optionally, the movable shielding plate is disposed between the plasma generation source and the substrate, and includes a three-layer nested structure of a magnetic shielding plate, an openable blade array, and an asymmetric blade array. The differentiated configuration of the movable shielding plate at each stage includes: During the main etching stage, the opening degree of the openable blade array is controlled to be in the first opening degree throttling mode, forming a local high-pressure zone above the etching area to increase the plasma density. During the over-etching stage, the blade opening is gradually increased from the first opening to the second opening, switching to a uniform mode to eliminate local pressure differences; During the charge release phase, the blades are quickly closed to the third opening degree of the shutdown mode to isolate the direct bombardment of the plasma on the substrate.

[0009] Optionally, a first depth threshold is dynamically calculated based on the optimal estimate. Second depth threshold ,include: Target etching depth Based on the baseline, the optimal estimate of the current etching depth is obtained by combining the real-time output of the extended Kalman filter. And the optimal estimate of the current etching rate , set the first depth threshold Second depth threshold Bind to the optimal estimate of the current etching depth. And the optimal estimate of the current etching rate The function is determined so that the timing of stage switching can be adaptively adjusted according to the fluctuations in the actual etching rate and actual etching depth.

[0010] Optionally, depth feedback-based dry etching control methods also include: Continuously monitor the optimal estimate of the current etching rate obtained by the extended Kalman filter. When multiple consecutive sampling points meet the condition that the etching rate continuously decreases by more than a preset proportion of the average etching rate of the previous steady-state stage, it is determined that the region has entered the rate decay zone, and the first depth threshold is immediately recalculated. Second depth threshold .

[0011] Optionally, depth feedback-based dry etching control methods also include: During the main etching stage, if the charge potential difference detected by charge sensors located in different areas of the substrate exceeds a preset safety threshold, the first depth threshold is actively lowered according to a preset charge feedback adjustment coefficient. .

[0012] Optionally, depth feedback-based dry etching control methods also include: During the charge release phase, the charge potential difference detected by charge sensors deployed in different areas of the substrate is monitored in real time. The maximum value of the potential difference of each charge is compared with half of the preset safety threshold to determine whether the maximum value of the potential difference of each charge is less than half of the preset safety threshold. If so, the charge release is determined to be complete, and the charge release phase is exited prematurely. If not, the duration of the pulsed magnetic field will be automatically extended or the pulse frequency and / or duty cycle will be adjusted until the maximum value of the potential difference among the charges is less than half of the preset safety threshold.

[0013] Optionally, in constructing the state-space model of the dry etching process and fusing the real-time monitoring data using extended Kalman filtering, the process further includes: Real-time monitoring of the covariance matching ratio of the innovation sequence in the extended Kalman filter; When the covariance matching ratio is greater than the first preset ratio, the process noise covariance matrix is ​​temporarily enhanced by multiplying the fading factor. When the covariance matching ratio is less than the second preset ratio, the measurement noise covariance matrix is ​​reduced, wherein the first preset ratio is greater than the second preset ratio.

[0014] Optionally, the state vector of the state-space model is ,in At the current etching depth, At the current etching rate, For equipment drift parameters, This is the etching rate attenuation factor; The observation vector of the state-space model ,in A depth measurement signal characterizing the etching depth, The optical emission spectrum signal characterizes the etching rate.

[0015] Secondly, the present invention also provides a dry etching apparatus, comprising: Reaction chamber; An electromagnetic coil array, with at least three layers of independently controllable electromagnetic coil groups arranged coaxially around the reaction chamber, each electromagnetic coil group including four independently controlled sub-coils, corresponding to the four quadrants of the reaction chamber respectively; A movable shielding plate is disposed between the plasma generation source and the substrate, comprising a three-layer nested structure of a magnetic shielding plate, an openable blade array, and an asymmetric blade array. The openable blade array is driven by a servo motor to independently adjust the opening angle. Laser interferometers are used to monitor depth measurement signals that characterize etching depth in real time. An optical emission spectrometer is used to detect optical emission spectral signals that characterize etching rate in real time. The charge sensor array is deployed on the substrate for real-time monitoring of charge accumulation. An extended Kalman filter controller, together with the laser interferometer, the optical emission spectrometer, the charge sensor array, the electromagnetic coil array, and the movable shielding plate, is configured to perform the method described in the first aspect of the present invention.

[0016] This invention constructs a state-space model of the dry etching process and introduces an extended Kalman filter to fuse depth measurement signals with optical emission spectrum signals. During the etching process, it outputs optimal estimates of etching depth and etching rate in real time. Based on these optimal estimates, it dynamically calculates a first and a second depth threshold, using the real-time depth threshold to drive precise switching between the main etching stage, the over-etching stage, and the charge release stage. Simultaneously, it differentiates the configuration of the electromagnetic coil array and the movable shielding plate at each stage, ensuring different magnetic field distributions and shielding plate openings for each stage. This achieves three-stage coordinated control: high-energy focusing in the main etching stage, uniform deceleration in the over-etching stage, and active neutralization in the charge release stage. This effectively solves the technical problem of low etching success rate caused by the contradiction between charge accumulation and stage requirements in high aspect ratio etching, improving the etching success rate of high aspect ratio structures. Furthermore, the real-time optimal estimation capability of the extended Kalman filter allows the stage switching threshold to automatically update with the dynamic changes in the etching rate, effectively avoiding premature or late switching due to etching rate fluctuations.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of a dry etching apparatus provided by the present invention; Figure 2 A schematic diagram of the structure of an electromagnetic coil assembly provided by the present invention; Figure 3 A schematic diagram of a movable shielding plate provided by the present invention; Figure 4 A flowchart of a laser processing quality control method provided by the present invention; Figure 5 A principle block diagram of extended Kalman filter state estimation and dynamic threshold calculation provided by the present invention; Figure 6 A schematic diagram of a dry etching control device based on depth feedback provided by the present invention; Figure 7This is a schematic diagram of the structure of an electronic device provided by the present invention.

[0020] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] Figure 1 This is a schematic diagram of the overall structure of a dry etching apparatus provided by the present invention, as shown below. Figure 1 As shown, the dry etching equipment includes a reaction chamber 1, an electromagnetic coil array 10, a movable shielding plate 20, a real-time monitoring and feedback unit, and an extended Kalman filter controller.

[0024] Figure 2 A schematic diagram of an electromagnetic coil assembly provided by the present invention is shown below. Figure 1 , Figure 2An electromagnetic coil array 10 is coaxially arranged with three layers of independently controllable electromagnetic coil groups around the reaction chamber 1. The first coil group 11 is located at the upper part of the chamber 1 and is used to guide plasma injection; the second coil group 12 is located in the middle section of the chamber 1 and is used to generate a gradient magnetic field to form a "magnetic lens"; the third coil group 13 is located at the bottom of the chamber 1 and is used to cancel stray magnetic fields and enhance the magnetic field gradient in the focusing area. Each coil group can be divided into four independently controllable sub-coils 101, corresponding to the four quadrants of the chamber 1, and the current in each quadrant can be adjusted independently to compensate for the uneven magnetic field distribution in different areas of the substrate. The coil driving mode supports both steady-state DC mode and pulse mode, which is switched by an extended Kalman filter controller according to the process stage. In this embodiment, each layer of coil has 120 turns and a maximum current of 10A.

[0025] Figure 3 A schematic diagram of a movable shielding plate provided by the present invention is shown below. Figure 3 A movable shielding plate 20 is disposed between the plasma generation source and the substrate, employing a three-layer nested structure. The first layer is a magnetic shielding plate 21, made of insulating material (such as alumina), used to block ion sputtering and shield stray electric fields; the second layer is an openable blade array 22, composed of multiple fan-shaped blades that rotate independently around a pivot, each blade driven by a servo motor, allowing for real-time adjustment of the opening angle; in this embodiment, the number of blades is 32; the third layer is an asymmetric blade array 23, used for precise local control of specific areas at the edge of the substrate. The movable shielding plate 20 supports three operating modes: throttling mode (blades partially closed), uniform mode (blades fully open), and shut-off mode (blades closed to minimum opening).

[0026] The real-time monitoring and feedback unit includes an etching depth monitoring module and a charge accumulation monitoring module. The etching depth monitoring module includes a laser interferometer and an optical emission spectrometer. The laser interferometer (wavelength 633nm) is used to measure the etching depth in real time, and the optical emission spectrometer is used for endpoint detection and etching rate monitoring. The charge accumulation monitoring module includes an array of embedded charge sensors deployed in different areas of the substrate. In this embodiment, a 9-point charge sensor array is used to monitor the charge potential difference in each area in real time. All of the above monitoring modules are connected to an extended Kalman filter controller.

[0027] The extended Kalman filter controller is connected to the laser interferometer, optical emission spectrometer, charge sensor array, electromagnetic coil array 10, and movable shielding plate 20, respectively. The extended Kalman filter controller includes a programmable logic controller (implemented by FPGA in this embodiment, with a sampling frequency of 2kHz) and a non-transient computer-readable medium storing control instructions. It is configured to receive feedback signals from the monitoring unit, execute the extended Kalman filter (EFK Carman) recursive algorithm, output the optimal estimates of etching depth and etching rate in real time, dynamically calculate the stage switching threshold, and output control signals to electromagnetic coil array 10 and movable shielding plate 20.

[0028] Figure 4 This invention provides a flowchart of a laser processing quality control method, applicable to the dry etching process of high aspect ratio through-silicon vias (TSVs) on G8.5 generation glass substrates (2200mm × 2500mm). The substrate material is silicon, and the target etching depth is... The depth is 100 μm with an aspect ratio of 30:1. This method can be executed by the depth feedback-based dry etching control device provided by this invention. This device can be implemented in software and / or hardware and is typically configured in electronic devices, such as... Figure 4 As shown, the dry etching control method based on depth feedback includes the following steps: S101. Obtain real-time monitoring data of the etching process.

[0029] In this embodiment of the invention, during the dry etching process, the real-time monitoring data includes at least a depth measurement signal characterizing the etching depth and an optical emission spectrum signal characterizing the etching rate. For example, a laser interferometer is used to acquire the depth measurement signal characterizing the etching depth, and an optical emission spectrometer is used to acquire the optical emission spectrum signal characterizing the etching rate. In this embodiment, the laser interferometer emits a 633nm laser beam to irradiate the bottom of the etching trench, and the etching depth is calculated in real time by detecting changes in the interference fringes of the reflected light; the optical emission spectrometer detects changes in the intensity of characteristic spectral lines of specific reactants or products in the plasma (such as characteristic spectral lines of active particles like Si, SiO2, F, and Cl), indirectly reflecting the etching rate. Simultaneously, an array of nine charge sensors deployed in different areas of the substrate monitors the charge potential difference in each area in real time. (i=1,2,…,9).

[0030] S102. Construct a state-space model of the dry etching process, and perform real-time optimal estimation of etching depth and etching rate by fusing real-time monitoring data through extended Kalman filtering.

[0031] Before etching begins, the parameters in the state transition equation are calibrated through offline experiments to complete the model initialization. The state vector of the state-space model is defined as follows: ,in At the current etching depth, At the current etching rate, These are equipment drift parameters (characterizing slow-changing factors such as cavity aging and electrode contamination). This is the etching rate decay factor (describes the nonlinear decrease in rate as aspect ratio increases).

[0032] The state equations (process model) are described as follows: ; ; ; ; Where Δt is the sampling period. and The process noise, represented by the drift parameter and the attenuation factor, follows a zero-mean Gaussian distribution.

[0033] Observation vectors of the state-space model ,in A depth measurement signal characterizing the etching depth, The optical emission spectrum signal characterizes the etching rate.

[0034] The observation equation is a nonlinear function : ; ; in This is the spectral sensitivity coefficient. and For measuring noise.

[0035] Figure 5 This invention provides a principle block diagram for extended Kalman filter state estimation and dynamic threshold calculation, referencing... Figure 5 In each sampling period (0.5ms in this embodiment), the extended Kalman filter controller sequentially performs two stages: time update and measurement update. In the time update stage, the prior state estimate is calculated based on the state estimate and state equation of the previous moment. and prior error covariance In the measurement update phase, the depth measurements from the laser interferometer and the rate correlation signal from the optical emission spectrometer are fused to calculate the Kalman gain, which is then used to update the posterior state estimate. and posterior error covariance Through the above filtering process, the optimal estimate of the current etching depth is output. And the optimal estimate of the current etching rate .

[0036] In some embodiments of the present invention, during the process of constructing a state-space model of the dry etching process and fusing the real-time monitoring data using an extended Kalman filter, the process further includes adaptive adjustment of the extended Kalman filter parameters to address the issue of changes in the statistical characteristics of process noise and measurement noise as the process progresses. The adaptive adjustment process of the extended Kalman filter parameters is as follows: Real-time monitoring of the innovation sequence of the extended Kalman filter Covariance matching ratio , Defined as the ratio of the trace of the actual innovation covariance to the trace of the theoretical innovation covariance. When the value is greater than 1+ε, it indicates that the model uncertainty increases. The process noise covariance matrix Q is temporarily enhanced by doubling the fading factor λ (λ>1). When < 1-ε, it indicates that the measurement noise is overestimated, and the measurement noise covariance matrix R should be reduced proportionally; when At this time, Q and R remain unchanged; where ε ranges from 0.2 to 0.4, and in this embodiment, ε=0.3 is preferred. Through adaptive covariance adjustment, the system can achieve adaptive compensation for cavity aging and process drift, improve the filtering estimation accuracy during the rapid etching rate change stage, and ensure that the extended Kalman filter maintains optimal estimation performance throughout the entire process window.

[0037] S103. Dynamically calculate the first depth threshold and the second depth threshold based on the optimal estimate.

[0038] The optimal estimate of the current etching depth based on the output of the extended Kalman filter controller. And the optimal estimate of the current etching rate The first depth threshold D1 and the second depth threshold D2 are dynamically calculated.

[0039] In some embodiments of the present invention, the target etching depth is... Based on the baseline, the optimal estimate of the current etching depth is obtained by combining the real-time output of the extended Kalman filter. And the optimal estimate of the current etching rate , set the first depth threshold Second depth threshold Bind to the optimal estimate of the current etching depth. And the optimal estimate of the current etching rate The function is determined so that the timing of stage switching can be adaptively adjusted according to the fluctuations in the actual etching rate and actual etching depth.

[0040] In a specific embodiment of the present invention, the formula for calculating the dynamic threshold is: ; ; in, The target etching depth is predetermined by the process formulation. The minimum depth scaling factor for the main etching stage ranges from 0.60 to 0.75, and is preferred in this embodiment. =0.70; The minimum depth scaling factor for the over-etching stage ranges from 0.85 to 0.95, and is preferred in this embodiment. =0.90; and The preset remaining target time corresponds to the minimum duration requirements of the main etching stage and the over-etching stage, respectively. In this embodiment, it is set to 5 seconds and 3 seconds, respectively.

[0041] The above formula uses a max function to take the larger of the two values, ensuring that the threshold meets both the lower limit requirement of the depth ratio and sufficient duration for each stage. At faster etching rates, the remaining time term plays a dominant role, preventing premature stage switching; at slower etching rates, the depth ratio term plays a dominant role, ensuring each stage covers a sufficient depth range. The threshold is updated in real time as the etching process progresses, achieving dynamic adaptive adjustment.

[0042] In some embodiments of the present invention, the first depth threshold is dynamically calculated based on the optimal estimate. Second depth threshold It also includes rate decay inflection point detection and threshold adaptive correction. Specifically, during the etching process, due to the high aspect ratio effect or changes in process conditions, the etching rate may experience a sudden inflection point. When N consecutive sampling points (N=5 in this embodiment) satisfy... When a rate decay inflection point is detected, a recalculation is triggered. and .in This represents the average etching rate of the previous steady-state stage. The rate attenuation threshold coefficient ranges from 0.15 to 0.20, and is preferably used in this embodiment. =0.18. This mechanism ensures that the stage switching threshold is adjusted in a timely manner when the etching rate changes significantly, avoiding deviations in switching timing due to sudden rate changes.

[0043] S104. Perform a phase switch based on the comparison result between the optimal estimated value of the current etching depth and the first depth threshold and the second depth threshold.

[0044] In each sampling period, the optimal estimate of the current etching depth is... With the first depth threshold Second depth threshold Compare, according to and , The comparison results are switched during the execution phase. Specifically, when... During the main etching phase, when During the etching phase, when The charge release phase is executed at that time.

[0045] S105. For the main etching stage, the over-etching stage and the charge release stage, the electromagnetic coil array and the movable shield are configured differently so that different magnetic field distributions and shield openings correspond to different stages.

[0046] During the main etching stage, the magnetic shielding system (including an electromagnetic coil array and a movable shielding plate) is controlled to enter a high-energy focusing mode. The core objective of the main etching stage is to obtain a high etching rate and good anisotropy; therefore, it is necessary to focus the plasma on the central region of the substrate to increase ion flux and energy. Specifically, the high-energy focusing mode includes: setting the current of the middle coil group (second coil group 12) in the electromagnetic coil group to its maximum value, and configuring the current of other electromagnetic coil groups according to a preset proportion of the maximum value (e.g., 50%), generating a strong axial magnetic field to confine the plasma towards the center; simultaneously, controlling the opening degree of the openable blade array of the movable shielding plate to a first opening degree of 30% to 50% (preferably 40% in this embodiment), activating the throttling mode, and further enhancing the central focusing effect of the plasma through the physical confinement effect of the shielding plate. In this mode, the plasma density in the central region can be increased by more than 40%, and the etching rate is significantly improved.

[0047] During the over-etching stage, the magnetic shielding system is controlled to enter a uniform deceleration mode. As the etching depth increases, the high aspect ratio effect intensifies, and the core objective of the over-etching stage shifts to improving in-plane uniformity and preventing over-etching and damage to the underlying layers. The uniform deceleration mode specifically includes: gradually reducing the current in the middle coil group (second coil group 12) from its maximum value to equal that of other electromagnetic coil groups, weakening the magnetic field confinement and expanding the plasma distribution range; simultaneously, gradually increasing the opening degree of the movable shielding plate's openable blade array from the first opening degree to the second opening degree (e.g., 100%), fully opening the shielding plate, activating the uniform mode, eliminating the physical confinement effect, and ensuring uniform plasma distribution. The changes in current and opening degree employ a linear ramp method with a transition time of 3 to 8 seconds to avoid plasma instability caused by sudden parameter changes. In this mode, the in-plane etching uniformity of the G8.5 substrate can be controlled within ±2%.

[0048] During the charge release phase, the magnetic shielding system is controlled to enter a pulsed discharge active neutralization mode. As etching nears completion, the positive charge accumulated at the bottom of the trench needs to be effectively released; otherwise, defects such as arc discharge and sidewall twisting may occur. The pulsed discharge active neutralization mode involves switching the electromagnetic coil array of the magnetic shielding system to pulsed current. Specific parameters are: pulse frequency of 10Hz to 500Hz (preferably 100Hz in this embodiment), duty cycle of 30% to 70% (preferably 50% in this embodiment), and pulse peak current of 30% to 60% of the maximum current. Simultaneously, the openable blade array of the movable shielding plate is rapidly closed to a third opening degree of 0% to 20% (preferably 10% in this embodiment) in a shutdown mode, forming a semi-enclosed magnetic confinement space. The pulsed current generates a periodically changing magnetic field, driving electrons in the plasma to oscillate, increasing the probability of electrons reaching the bottom of the trench, thereby actively neutralizing the positive charge accumulated at the bottom. Compared to natural dissipation, the charge release efficiency is more than doubled.

[0049] In some embodiments of the present invention, during the main etching stage, the charge potential difference of charge sensors deployed in different regions of the substrate is monitored in real time. Determine the maximum value of the potential difference among the charges. Has the preset safety threshold been exceeded? If so, it means the charge accumulation rate exceeds expectations. In this case, the first depth threshold is actively lowered according to the preset charge feedback adjustment coefficient. This allows the system to enter the over-etching stage earlier, avoiding damage from charge accumulation.

[0050] For example, the preset charge feedback adjustment coefficient actively lowers the first depth threshold. The adjustment formula is: in The charge feedback gain coefficient ranges from 0.1 to 0.3, and is preferred in this embodiment. =0.2. This mechanism feeds back the charge state to the stage switching decision, achieving coordinated control of charge accumulation and etching process, and effectively preventing charge overload.

[0051] In some embodiments of the present invention, a charge release closed-loop confirmation step is further included in the charge release phase. For example, the extended Kalman filter controller acquires the charge potential difference of each charge sensor array in real time. Determine the maximum value of the potential difference among the charges. Is it less than If so, the charge release is considered complete, and the charge release phase is exited prematurely; otherwise, according to... The pulse frequency and duty cycle are dynamically adjusted. For example, the pulse frequency... Duty cycle ,in and This is a preset scaling factor. This closed-loop mechanism ensures that the charge is fully and efficiently released after each etching, avoiding charge residue from affecting subsequent processes.

[0052] It should be noted that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0053] Figure 6 A schematic diagram of a dry etching control device based on depth feedback provided by the present invention is shown below. Figure 6 As shown, the depth feedback-based dry etching control device includes: The monitoring data acquisition module 201 is used to acquire real-time monitoring data of the etching process. The real-time monitoring data includes at least a depth measurement signal characterizing the etching depth and an optical emission spectrum signal characterizing the etching rate. The filtering and estimation module 202 is used to construct a state-space model of the dry etching process. It fuses the real-time monitoring data using an extended Kalman filter to perform real-time optimal estimation of the etching depth and etching rate, obtaining the optimal estimate of the current etching depth. And the optimal estimate of the current etching rate ; The dynamic threshold calculation module 203 is used to dynamically calculate the first depth threshold based on the optimal estimate. Second depth threshold ; Phase switching module 204, used to switch phases according to and , Comparison result execution phase switching: when During the main etching phase, when During the etching phase, when The charge release phase is executed at that time; The differentiated configuration module 205 is used to differentiate the configuration of the electromagnetic coil array and the movable shielding plate for the main etching stage, the over-etching stage and the charge release stage, so that different magnetic field distributions and shielding plate openings correspond to different stages.

[0054] In some embodiments of the present invention, the electromagnetic coil array is coaxially arranged around the reaction chamber with at least three layers of independently controllable electromagnetic coil groups. Each layer of electromagnetic coil group includes four independently controlled sub-coils corresponding to the four quadrants of the chamber. The differentiated configuration module 205 includes: The first current configuration submodule is used to set the current of the electromagnetic coil group located in the middle of the chamber to the maximum value during the main etching stage, and configure the current of other electromagnetic coil groups according to a preset ratio of the maximum value to form a strong gradient magnetic field, which vertically focuses the plasma onto the substrate surface. The second current configuration submodule is used to gradually reduce the current of the electromagnetic coil group located in the middle of the chamber from its maximum value to the same value as other electromagnetic coil groups during the over-etching stage, thereby weakening the magnetic field focusing and making the plasma distribution more uniform. The third current configuration submodule is used to switch the electromagnetic coil array to pulse mode during the charge release phase to actively neutralize the positive charge accumulated at the bottom of the trench.

[0055] In some embodiments of the present invention, the movable shielding plate is disposed between the plasma generation source and the substrate, and includes a three-layer nested structure of a magnetic shielding plate, an openable blade array, and an asymmetric blade array. The differentiated configuration module 205 includes: The first opening configuration submodule is used to control the opening of the openable blade array to be in the first opening throttling mode during the main etching stage, so as to form a local high pressure zone above the etching area to increase the plasma density. The second opening configuration submodule is used to gradually increase the blade opening from the first opening to the second opening during the over-etching stage, switch to uniform mode, and eliminate local pressure difference. The third opening configuration submodule is used to quickly close the blades to the third opening shutdown mode during the charge release phase, thus isolating the substrate from direct plasma bombardment.

[0056] In some embodiments of the present invention, the dynamic threshold calculation module 203 includes: The adaptive adjustment submodule is used to adjust the etching depth to the target depth. Based on the baseline, the optimal estimate of the current etching depth is obtained by combining the real-time output of the extended Kalman filter. And the optimal estimate of the current etching rate , set the first depth threshold Second depth threshold Bind to the optimal estimate of the current etching depth. And the optimal estimate of the current etching rate The function is determined so that the timing of stage switching can be adaptively adjusted according to the fluctuations in the actual etching rate and actual etching depth.

[0057] In some embodiments of the present invention, the dry etching control device based on depth feedback further includes: The inflection point monitoring module is used to continuously monitor the optimal estimate of the current etching rate obtained by the extended Kalman filter. When multiple consecutive sampling points meet the condition that the etching rate continuously decreases by more than a preset proportion of the average etching rate of the previous steady-state stage, it is determined that the region has entered the rate decay zone, and the first depth threshold is immediately recalculated. Second depth threshold .

[0058] In some embodiments of the present invention, the dry etching control device based on depth feedback further includes: The first depth threshold reduction module is used to actively reduce the first depth threshold according to a preset charge feedback adjustment coefficient if the charge potential difference detected by charge sensors located in different areas of the substrate exceeds a preset safety threshold during the main etching stage. .

[0059] In some embodiments of the present invention, the dry etching control device based on depth feedback further includes: The potential difference monitoring module is used to monitor the charge potential difference detected by charge sensors deployed in different areas of the substrate in real time during the charge release phase. The potential difference comparison module is used to compare the maximum value of the potential difference of each charge with half of the preset safety threshold to determine whether the maximum value of the potential difference of each charge is less than half of the preset safety threshold. The phase exit module is used to determine that the charge release is complete and exit the charge release phase in advance when the maximum value of the potential difference among the charges is less than half of the preset safety threshold. The pulse adjustment module is used to automatically extend the duration of the pulse magnetic field or adjust the pulse frequency and / or duty cycle when the maximum value of the potential difference among the charges is greater than or equal to half of the preset safety threshold, until the maximum value of the potential difference among the charges is less than half of the preset safety threshold.

[0060] In some embodiments of the present invention, the dry etching control device based on depth feedback further includes: The covariance matching ratio monitoring module is used to monitor the covariance matching ratio of the innovation sequence of the extended Kalman filter in real time during the process of constructing the state space model of the dry etching process and fusing the real-time monitoring data through extended Kalman filtering. The enhancement module is used to temporarily enhance the process noise covariance matrix by multiplying the fading factor when the covariance matching ratio is greater than a first preset ratio. The reduction module is used to reduce the measurement noise covariance matrix when the covariance matching ratio is less than a second preset ratio, wherein the first preset ratio is greater than the second preset ratio.

[0061] In some embodiments of the present invention, the state vector of the state-space model is ,in At the current etching depth, At the current etching rate, For equipment drift parameters, This is the etching rate attenuation factor; The observation vector of the state-space model ,in A depth measurement signal characterizing the etching depth, The optical emission spectrum signal characterizes the etching rate.

[0062] It should be noted that the module division in the various depth feedback-based dry etching control devices provided in the above embodiments is illustrative and only represents one logical functional division. In actual implementation, other division methods may also be used. Furthermore, the functional modules in the various embodiments of this invention can be integrated into a single processor, exist as separate physical entities, or be integrated into a single module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0063] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the technical solution of the embodiments of the present invention can be embodied in the form of a computer program product, which is stored in a computer storage medium and includes several instructions to cause an electronic device or processor to execute all or part of the steps of the methods in the various embodiments of the present invention. The aforementioned computer storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0064] The dry etching control device based on depth feedback and the dry etching control method based on depth feedback provided in the above embodiments belong to the same concept. The dry etching control device based on depth feedback can execute the dry etching control method based on depth feedback provided in the foregoing embodiments of the present invention, and has the corresponding functional modules and beneficial effects of executing the dry etching control method based on depth feedback. For details of its specific implementation process, please refer to the method embodiments, which will not be repeated here.

[0065] Figure 7This is a schematic diagram of an electronic device provided by the present invention. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (such as helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0066] like Figure 7 As shown, the electronic device includes at least one processor 301 and a memory, such as a read-only memory (ROM) 302 or a random access memory (RAM) 303, communicatively connected to the at least one processor 301. The memory stores computer programs executable by the at least one processor. The processor 301 can perform various appropriate actions and processes based on the computer program stored in the ROM 302 or loaded into the RAM 303 from storage unit 308. The RAM 303 can also store various programs and data required for the operation of the electronic device. The processor 301, ROM 302, and RAM 303 are interconnected via a bus 304. An input / output (I / O) interface 305 is also connected to the bus 304.

[0067] Multiple components in the electronic device are connected to the I / O interface 305, including: an input unit 306, such as a keyboard, mouse, etc.; an output unit 307, such as various types of displays, speakers, etc.; a storage unit 308, such as a disk, optical disk, etc.; and a communication unit 309, such as a network card, modem, wireless transceiver, etc. The communication unit 309 allows the electronic device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0068] Processor 301 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 301 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, digital signal processors (DSPs), and any suitable processor, controller, microcontroller, etc. Processor 301 performs the various methods and processes described above, such as the dry etching control method based on deep feedback.

[0069] In some embodiments, the depth feedback-based dry etching control method can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 308. In some embodiments, part or all of the computer program can be loaded and / or mounted on an electronic device via ROM 302 and / or communication unit 309. When the computer program is loaded into RAM 303 and executed by processor 301, one or more steps of the depth feedback-based dry etching control method described above can be performed. Alternatively, in other embodiments, processor 301 can be configured to perform the depth feedback-based dry etching control method by any other suitable means (e.g., by means of firmware).

[0070] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0071] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0072] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0073] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0074] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or middleware components (e.g., application servers), or frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0075] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0076] This invention also provides a computer program product, including a computer program that, when executed by a processor, implements the dry etching control method based on depth feedback as provided in any embodiment of this application.

[0077] In implementing the computer program product, computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof. Programming languages ​​include object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0078] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0079] 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 be made according to 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. A dry etching control method based on depth feedback, characterized in that, include: Acquire real-time monitoring data of the etching process, wherein the real-time monitoring data includes at least a depth measurement signal characterizing the etching depth and an optical emission spectrum signal characterizing the etching rate; A state-space model of the dry etching process is constructed. The real-time monitoring data is fused using an extended Kalman filter to perform real-time optimal estimation of the etching depth and etching rate, thus obtaining the optimal estimate of the current etching depth. And the optimal estimate of the current etching rate ; The first depth threshold is dynamically calculated based on the optimal estimate. Second depth threshold ; according to and , Comparison result execution phase switching: when During the main etching phase, when During the etching phase, when The charge release phase is executed at that time; For the main etching stage, the over-etching stage, and the charge release stage, the electromagnetic coil array and the movable shield are configured differently so that different magnetic field distributions and shield openings correspond to different stages.

2. The dry etching control method based on depth feedback according to claim 1, characterized in that, The electromagnetic coil array is coaxially arranged around the reaction chamber with at least three layers of independently controllable electromagnetic coil groups. Each layer of electromagnetic coil group includes four independently controlled sub-coils corresponding to the four quadrants of the chamber. The differentiated configuration of the electromagnetic coil array at each stage includes: During the main etching stage, the current of the electromagnetic coil group located in the middle of the chamber is set to the maximum value, and the current of other electromagnetic coil groups is configured according to the preset ratio of the maximum value to form a strong gradient magnetic field, which vertically focuses the plasma onto the substrate surface. During the over-etching stage, the current of the electromagnetic coil group located in the middle of the chamber is gradually reduced from its maximum value to be equal to that of other electromagnetic coil groups, thereby weakening the magnetic field focusing and making the plasma distribution more uniform. During the charge release phase, the electromagnetic coil array is switched to pulse mode to actively neutralize the positive charge accumulated at the bottom of the trench.

3. The dry etching control method based on depth feedback according to claim 2, characterized in that, The movable shielding plate is disposed between the plasma generation source and the substrate, and includes a three-layer nested structure of a magnetic shielding plate, an openable blade array, and an asymmetric blade array. The differentiated configuration of the movable shielding plate at each stage includes: During the main etching stage, the opening degree of the openable blade array is controlled to be in the first opening degree throttling mode, forming a local high-pressure zone above the etching area to increase the plasma density. During the over-etching stage, the blade opening is gradually increased from the first opening to the second opening to switch to uniform mode and eliminate local pressure difference; During the charge release phase, the blades are quickly closed to the third opening degree of the shutdown mode to isolate the direct bombardment of the plasma on the substrate.

4. The dry etching control method based on depth feedback according to any one of claims 1-3, characterized in that, The first depth threshold is dynamically calculated based on the optimal estimate. Second depth threshold ,include: Target etching depth Based on the baseline, the optimal estimate of the current etching depth is obtained by combining the real-time output of the extended Kalman filter. And the optimal estimate of the current etching rate , set the first depth threshold Second depth threshold Bind to the optimal estimate of the current etching depth. And the optimal estimate of the current etching rate The function is determined so that the timing of stage switching can be adaptively adjusted according to the fluctuations in the actual etching rate and actual etching depth.

5. The dry etching control method based on depth feedback according to any one of claims 1-3, characterized in that, Also includes: Continuously monitor the optimal estimate of the current etching rate obtained by the extended Kalman filter. When multiple consecutive sampling points meet the condition that the etching rate continuously decreases by more than a preset proportion of the average etching rate of the previous steady-state stage, it is determined that the region has entered the rate decay zone, and the first depth threshold is immediately recalculated. Second depth threshold .

6. The dry etching control method based on depth feedback according to any one of claims 1-3, characterized in that, Also includes: During the main etching stage, if the charge potential difference detected by charge sensors located in different areas of the substrate exceeds a preset safety threshold, the first depth threshold is actively lowered according to a preset charge feedback adjustment coefficient. .

7. The dry etching control method based on depth feedback according to any one of claims 1-3, characterized in that, Also includes: During the charge release phase, the charge potential difference detected by charge sensors deployed in different areas of the substrate is monitored in real time. The maximum value of the potential difference of each charge is compared with half of the preset safety threshold to determine whether the maximum value of the potential difference of each charge is less than half of the preset safety threshold. If so, the charge release is determined to be complete, and the charge release phase is exited prematurely. If not, the duration of the pulsed magnetic field will be automatically extended or the pulse frequency and / or duty cycle will be adjusted until the maximum value of the potential difference among the charges is less than half of the preset safety threshold.

8. The dry etching control method based on depth feedback according to any one of claims 1-3, characterized in that, The process of constructing a state-space model of the dry etching process and fusing the real-time monitoring data using extended Kalman filtering also includes: Real-time monitoring of the covariance matching ratio of the innovation sequence in the extended Kalman filter; When the covariance matching ratio is greater than the first preset ratio, the process noise covariance matrix is ​​temporarily enhanced by multiplying the fading factor. When the covariance matching ratio is less than the second preset ratio, the measurement noise covariance matrix is ​​reduced, wherein the first preset ratio is greater than the second preset ratio.

9. The dry etching control method based on depth feedback according to any one of claims 1-3, characterized in that, The state vector of the state-space model is: ,in At the current etching depth, At the current etching rate, For equipment drift parameters, This is the etching rate attenuation factor; The observation vector of the state-space model ,in A depth measurement signal characterizing the etching depth, The optical emission spectrum signal characterizes the etching rate.

10. A dry etching apparatus, characterized in that, include: Reaction chamber; An electromagnetic coil array, with at least three layers of independently controllable electromagnetic coil groups arranged coaxially around the reaction chamber, each electromagnetic coil group including four independently controlled sub-coils, corresponding to the four quadrants of the reaction chamber respectively; A movable shielding plate is disposed between the plasma generation source and the substrate, comprising a three-layer nested structure of a magnetic shielding plate, an openable blade array, and an asymmetric blade array. The openable blade array is driven by a servo motor to independently adjust the opening angle. Laser interferometers are used to monitor depth measurement signals that characterize etching depth in real time. An optical emission spectrometer is used to detect optical emission spectral signals that characterize etching rate in real time. The charge sensor array is deployed on the substrate for real-time monitoring of charge accumulation. An extended Kalman filter controller, together with the laser interferometer, the optical emission spectrometer, the charge sensor array, the electromagnetic coil array, and the movable shield, is configured to perform the method according to any one of claims 1 to 9.

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