Pre-calibration method for switching time of screening window in cluster ion planarization processing

Abstract

The application relates to the technical field of optical processing, and discloses a pre-calibration method for switching time of a screening window in cluster ion planarization processing, which comprises the following steps: simulating the evolution of a surface topography to be processed, obtaining the evolution result of the surface topography to be processed with a wide screening window under processing conditions, and calculating the root mean square roughness value of the surface to be processed under different bombardment doses to obtain an evolution curve of the root mean square roughness value changing with the bombardment dose; determining a switching dose for switching from the wide screening window to a narrow screening window according to the descending rate of the evolution curve of the root mean square roughness value changing with the bombardment dose; and calculating the switching time of the wide screening window to the narrow screening window according to the switching dose. The application can realize segmented planarization processing of a gas cluster ion beam without relying on repeated verification after processing, and improve the predictability, repeatability and process efficiency of the processing process.

Description

Technical Field

[0001] This application relates to the field of optical processing technology, and more specifically to a method for pre-calibrating the switching time of the screening window in cluster ion planarization processing. Background Technology

[0002] With the development of fields such as extreme ultraviolet lithography, high-power laser systems, synchrotron radiation optics, and space optical remote sensing, high-end optical components are placing increasingly higher demands on surface morphology and surface roughness. Especially in short-wavelength optical systems, microscopic surface undulations can cause significant scattering loss and wavefront distortion, thus requiring ultra-smooth surfaces with sub-nanometer or even angstrom-level roughness.

[0003] Gas cluster ion beam technology is a non-contact, low-damage surface processing method. Unlike traditional single-atom ion beams, gas cluster ions consist of hundreds to thousands of gas atoms. Under the same accelerating voltage, the total energy of the cluster is shared by a large number of atoms, resulting in a lower average energy per individual atom. Therefore, when a gas cluster ion beam bombards a material surface, the energy is mainly deposited in the shallow surface region, inducing lateral migration and local rearrangement of surface atoms, thereby achieving low-damage, smooth processing.

[0004] In gas cluster ion beam processing, cluster size is one of the key process parameters affecting the processing effect. Cluster size determines the impact scale of a single bombardment, the energy deposition range, the bombardment crater size, the lateral migration range, and the redistribution of migrated matter. The beams generated by actual cluster sources typically have a certain size distribution and may contain particles such as single-atom ions and small clusters that do not meet the requirements for ultra-smooth processing. Therefore, it is necessary to control the range of cluster sizes entering the processing region through a quality / size screening structure.

[0005] Different screening window widths correspond to different process characteristics. Wide screening windows can reject single-atom ions and small clusters while allowing effective clusters within a wider size range to pass through, resulting in higher beam current and processing efficiency, suitable for rapidly reducing surface roughness in the initial stages of processing. Narrow screening windows allow for a more concentrated cluster size, improving the consistency of single-bombardment response, suitable for later finishing, but reducing beam current and processing efficiency. Therefore, wide and narrow screening windows are suitable for pre-planarization and finishing stages, respectively. Determining the switching timing between these two stages is a problem that needs to be solved in the efficient ultra-smooth processing of gas cluster ion beams.

[0006] If the timing of switching the screening window depends on repeated verification after processing, it will increase the processing complexity and time cost; if the timing of switching is determined solely by experience, it will be difficult to adapt to different initial surface conditions, cluster size distributions and beam current conditions, resulting in insufficient process repeatability and predictability. Summary of the Invention

[0007] To address the above problems, this application proposes a pre-calibration method for the switching time of the screening window during cluster ion planarization processing, thereby resolving at least one of the aforementioned issues. The specific solution is as follows: According to a specific embodiment of this application, this application provides a method for pre-calibrating the switching time of the screening window in cluster ion planarization processing, comprising the following steps: The evolution of the surface morphology to be processed is simulated to obtain the evolution results of the surface morphology to be processed with the bombardment dose under the processing condition of wide screening window, and the root mean square roughness value of the surface to be processed under different bombardment doses is calculated to obtain the evolution curve of the root mean square roughness value with the bombardment dose. The switching dose for switching from a wide screening window to a narrow screening window is determined based on the rate of decrease of the root mean square roughness value as a function of bombardment dose. The switching time from the wide screening window to the narrow screening window is calculated based on the switching dose.

[0008] In some embodiments, the wide screening window allows effective cluster ions within a first size range to pass through; the narrow screening window allows effective cluster ions within a second size range to pass through, the first size range including the second size range.

[0009] In some embodiments, the simulation of the morphological evolution of the surface to be processed includes: Obtain the initial morphological parameters of the surface to be processed; Determine the cluster ion processing parameters, the cluster size range corresponding to wide and narrow screening windows, and the beam current; Based on the initial morphology parameters, the cluster ion processing parameters, the cluster size range corresponding to the wide and narrow screening windows, and the beam current, the morphology evolution of the surface to be processed is simulated.

[0010] In some embodiments, determining the switching dose for switching from a wide screening window to a narrow screening window based on the rate of decrease of the evolution curve of the root mean square roughness value as a function of bombardment dose includes: Calculate the rate of decrease of the root mean square roughness value as a function of bombardment dose. , ; in, Indicates dose range ( , The decrease in RMS caused by a unit dose within the range, where RMS represents the root mean square roughness value; The maximum rate of decrease of the root mean square roughness (RMS) value in the evolution curve of RMS as a function of bombardment dose is: And set the descent rate threshold to α, when the following condition is met: At that time, the endpoint dose of the determined dose interval The switching dose for switching from a wide screening window to a narrow screening window is denoted as . .

[0011] In some embodiments, the value of α ranges from 0.1 to 0.3.

[0012] In some embodiments, when at least two dose intervals satisfy: At that time, the endpoint dose of the determined dose interval Switching dose for switching from a wide screening window to a narrow screening window .

[0013] In some embodiments, calculating the switching time from the wide screening window to the narrow screening window based on the switching dose includes: The switching time from the wide filter window to the narrow filter window is calculated using the following formula: ; in, To switch time, To switch dosages, A is the surface area to be processed, q is the charge of cluster ions, and e is the elementary charge. This refers to the beam current in wide-screen window mode.

[0014] In some embodiments, the wide and narrow screening windows are formed by an electromagnetic screening structure, which includes upper and lower permanent magnets and an electrode plate disposed between the upper and lower permanent magnets; by adjusting the voltage applied to the electrode plate, the deflection trajectory of cluster ions under the combined action of magnetic and electric fields is changed, thereby adjusting the size range of cluster ions and the width of the screening window.

[0015] In some embodiments, the deflection range of cluster ions in the y-direction in the electromagnetic sieving structure satisfies the following formula: ; Where B is the magnetic flux density of the upper and lower permanent magnets. It is the magnitude of the accelerating voltage. It is the magnitude of the deflection voltage. It is the electrode plate spacing. The total length of the electromagnetic field. Let be the length of the electric field. The distance traveled away from the electromagnetic field is q, where q is the charge of the cluster ion and m is the charge of the cluster ion.

[0016] In some embodiments, the magnetic induction intensity of the upper and lower permanent magnets is 0.3T.

[0017] Compared with the prior art, the above-described solutions of this application have at least the following beneficial effects: This application proposes a pre-calibration method for the switching time of the screening window in gas cluster ion planarization processing. This method forms a wide screening window and a narrow screening window through an electromagnetic screening structure, and pre-determines the dose and time for switching from the wide screening window to the narrow screening window based on screening structure simulation, surface morphology evolution simulation, and beam current parameters. This method enables segmented planarization processing of gas cluster ion beams without relying on repeated verification after processing, improving the predictability, repeatability, and process efficiency of the processing.

[0018] This application enables the same gas cluster ion beam processing system to switch between a wide screening window mode and a narrow screening window mode by adjusting the compensation voltage of the screening structure. The wide screening window is used to remove monatomic ions and small-sized clusters while retaining effective clusters within a wider size range; the narrow screening window is used to further narrow the size range of the clusters that can pass through, thereby improving the consistency of the cluster bombardment response during the finishing stage.

[0019] This application does not use a single fixed screening window to complete all processing. Instead, it uses cluster beams with different size distributions according to the processing stage. In the early stage of processing, a wide screening window mode is used to perform rapid pre-planarization with higher beam flux. In the later stage of processing, it switches to a narrow screening window mode to perform low-disturbance finishing with cluster beams with more concentrated size distribution, thereby balancing processing efficiency and final surface quality.

[0020] This application obtains the evolution relationship of surface roughness with bombardment dose under wide screening window processing conditions through surface morphology evolution simulation before processing. The switching dose for switching from wide screening window mode to narrow screening window mode is determined based on the roughness decrease rate, avoiding reliance on manual experience to determine the switching timing.

[0021] This application obtains the range of cluster sizes and beam currents passing through different screening windows through ion trajectory simulation and beam calibration. Based on the relationship between dose, current, and processing area, the switching dose determined in the simulation is converted into the actual switching time during processing. In actual processing, the electromagnetic screening structure parameters only need to be adjusted after the preset switching time is reached to complete the process stage switching. This feature is suitable for gas cluster ion beam processing in a vacuum environment, reducing processing interruptions and saving time and costs. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 This is a schematic diagram of the pre-calibration method provided in the embodiments of this application; Figure 2 This is a schematic diagram of a gas cluster ion beam processing system provided in an embodiment of this application; Figure 3 Simulation diagram of ion trajectory with wide screening window and magnetic field deflection only, provided for embodiments of this application; Figure 4 Simulation diagram of ion trajectory in a narrow screening window for electromagnetic screening provided in the embodiments of this application; Figure 5 The RMS value versus dose graph provided in the embodiments of this application; Figure 6 This is a diagram showing the evolution of the surface morphology to be processed, provided in an embodiment of this application. Figure 7 The dose switching point is calculated for the embodiments of this application.

[0023] Explanation of reference numerals in the attached figures: 1. Gas source, 2. Nozzle, 3. Filter, 4. Ionizer, 5. Accelerating electrode, 6. Electromagnetic screening structure, 7. Neutralizer, 8. Beam limiting aperture, 9. Sample to be processed, 10. Mechanical scanning stage, 11. Faraday cup. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the product or device that includes that element.

[0026] Gas cluster ion beam ultrasmoothing is a non-contact, low-damage precision surface processing technology commonly used for ultrasmoothing the surfaces of optical components, semiconductor substrates, and optical thin films. Currently, this technology primarily improves surface roughness by adjusting process parameters such as cluster energy, cluster size, bombardment dose, gas type, and incident angle. Cluster size is a crucial parameter affecting processing results; different cluster sizes correspond to different bombardment scales, energy deposition ranges, and material migration capabilities. Since the beams generated by actual cluster sources typically exhibit a certain size distribution, quality / size screening structures are needed to remove non-target particles such as single-atom ions and small-sized clusters to ensure low-damage processing.

[0027] However, existing processes often use fixed screening windows or clusters within a fixed size range for processing, making it difficult to simultaneously achieve both processing efficiency and final surface quality. Wider screening windows can maintain higher beam current, suitable for rapid pre-planarization, but the cluster size dispersion during the finishing stage may limit the final roughness convergence; narrower screening windows can improve the consistency of cluster bombardment response, suitable for final finishing, but reduce beam current and processing efficiency. Furthermore, relying on downtime sampling or processing experience to determine the timing of screening window switching increases processing complexity and time costs.

[0028] Existing gas cluster ion beam ultrasmoothing processes mostly employ fixed cluster size screening windows or cluster beam currents within a fixed size range, making it difficult to simultaneously achieve processing efficiency and final surface quality. While wide screening windows offer high beam current and are suitable for rapid pre-planarization, the wider cluster size distribution during the finishing stage may affect the final roughness convergence. Narrow screening windows, on the other hand, provide better cluster size consistency, but the reduced beam current significantly increases processing time.

[0029] Furthermore, existing methods lack clear criteria for determining the switching dose and switching time when segmented switching between wide and narrow screening windows, easily relying on processing experience or post-processing sampling verification. Since gas cluster ion beam processing is usually carried out in a vacuum environment, downtime sampling efficiency is low, thus the predictability, repeatability, and processing efficiency of existing processes remain insufficient.

[0030] To this end, this application provides a pre-calibration method for the switching time of the screening window in the cluster ion segmented planarization process, comprising the following steps: simulating the evolution of the surface morphology to be processed, obtaining the evolution results of the surface morphology to be processed under the condition of wide screening window processing with the change of bombardment dose, and calculating the root mean square roughness value of the surface to be processed under different bombardment doses, obtaining the evolution curve of the root mean square roughness value with the change of bombardment dose; determining the switching dose for switching from a wide screening window to a narrow screening window based on the decreasing rate of the evolution curve of the root mean square roughness value with the change of bombardment dose; and calculating the switching time from the wide screening window to the narrow screening window based on the switching dose.

[0031] Based on the process requirements at different stages of gas cluster ion beam processing, this application divides the processing into a wide screening window pre-planarization stage and a narrow screening window finishing stage. The wide screening window is used to remove non-target particles such as monatomic ions and small-sized clusters, while maintaining a high beam flux and improving the processing efficiency in the early stages. The narrow screening window is used to improve the uniformity of cluster size distribution and the stability of later finishing, thereby balancing processing efficiency and final surface quality.

[0032] This application obtains the RMS evolution curve as a function of bombardment dose through surface morphology evolution simulation, and determines the dose for switching from a wide screening window to a narrow screening window based on whether the RMS decline rate is lower than a preset threshold; then, combining the beam current and processing area under the wide screening window, the switching dose is converted into switching time. This method does not rely on downtime sampling or repeated verification after processing, greatly saving the cost of repeated vacuuming.

[0033] This application combines electromagnetic screening structure simulation, cluster size distribution screening, and surface morphology evolution simulation to form a complete process for determining screening window parameters, switching dose, switching time, and segmented processing parameters. This process allows for pre-process parameter planning, improving the predictability, repeatability, and efficiency of segmented planarization of gas cluster ion beams.

[0034] The embodiments of this application are described in detail below with reference to the accompanying drawings.

[0035] According to specific embodiments of this application, this application provides a method for pre-calibrating the switching time of the screening window in cluster ion segmental planarization processing, such as... Figure 1 As shown, the method includes the following steps: S102: Simulate the evolution of the surface morphology to be processed, obtain the evolution results of the surface morphology to be processed under the processing condition of wide screening window with the change of bombardment dose, and calculate the root mean square roughness value of the surface to be processed under different bombardment doses, and obtain the evolution curve of the root mean square roughness value with the change of bombardment dose. S104: Determine the switching dose for switching from a wide screening window to a narrow screening window based on the rate of decrease of the root mean square roughness value as a function of bombardment dose. S106: Calculate the switching time from the wide screening window to the narrow screening window based on the switching dose.

[0036] In some embodiments, the wide screening window allows effective cluster ions within a first size range to pass through; the narrow screening window allows effective cluster ions within a second size range to pass through, the first size range including the second size range.

[0037] The gas cluster ion beam processing system used is as follows: Figure 2 As shown, the system mainly includes a gas source 1, a nozzle 2, a filter 3, an ionizer 4, an accelerating electrode 5, an electromagnetic screening structure 6, a neutralizer 7, a beam-limiting aperture 8, a sample to be processed 9, a mechanical scanning stage 10, and a Faraday cup 11. High-pressure gas undergoes ultrasonic expansion through the nozzle to form a neutral cluster beam. After passing through the filter and entering the ionization region, it is ionized by electron collisions and forms a charged gas cluster ion beam under the action of the accelerating electrode. Subsequently, the cluster ion beam enters the electromagnetic screening structure. Clusters of different sizes are deflected to different degrees in the electromagnetic field. Monoatomic ions and small-sized clusters are deflected or blocked. Clusters that meet the screening criteria enter the processing target chamber through the beam-limiting aperture for ultra-smooth processing of the sample. The Faraday cup is used to measure the beam current, and the mechanical scanning stage is used to realize the scanning motion of the sample relative to the beam.

[0038] This application employs an electromagnetic screening structure to control the size range of a gas cluster ion beam. This structure mainly consists of a permanent magnet, an electric field compensation electrode, an exit beam-limiting aperture, and a beam current detection component. After acceleration, the cluster ions enter the screening region. Due to their different mass-to-charge ratios, clusters of different sizes exhibit different deflection trajectories in the magnetic and electric fields. Therefore, by adjusting the magnetic field strength, electric field voltage, and exit aperture position, clusters within the target size range can pass through, while monatomic ions, small clusters, and other non-target particles are deflected or blocked.

[0039] In this embodiment, the screening structure uses a permanent magnet with a magnetic induction intensity of approximately 0.3T. For example... Figure 3 As shown, when no compensation voltage is applied, cluster ions are mainly deflected by the magnetic field. Since monatomic ions and small-sized clusters have a smaller mass-to-charge ratio and are more significantly deflected, they can be effectively removed by the screening structure. However, effective clusters in larger size ranges can still pass through the exit aperture. Figure 3 The red line indicates the aperture window (entering the processing area). For example... Figure 3 As shown, The following cannot pass through the aperture; only The left and right sides can pass through the aperture. This state can be used as a wide screening window mode for the pre-planarization stage in the early stage of processing to ensure a high beam flux.

[0040] like Figure 4 As shown, when a screening voltage is applied to the compensation electrode, the electric field deflects clusters within a specific velocity or size range towards the center of the axis, causing clusters near the target size to return to the central axis and pass through the exit aperture, while clusters deviating from the target size are blocked. By changing the compensation voltage, the center size of the clusters passing through and the width of the screening window can be adjusted, thereby forming a narrow screening window mode. Figure 4 As shown, The following sum is much greater than None of them can pass through the aperture, only The left and right sides can pass through the aperture. This mode is used in the later finishing stage of processing to improve cluster size uniformity and single bombardment response stability.

[0041] In some embodiments, the wide and narrow screening windows are formed by an electromagnetic screening structure, which includes upper and lower permanent magnets and an electrode plate disposed between the upper and lower permanent magnets; by adjusting the voltage applied to the electrode plate, the deflection trajectory of cluster ions under the combined action of magnetic and electric fields is changed, thereby adjusting the size range of cluster ions and the width of the screening window.

[0042] In some embodiments, the deflection range of cluster ions in the y-direction in the electromagnetic sieving structure satisfies the following formula: ; Where B is the magnetic flux density of the upper and lower permanent magnets. It is the magnitude of the accelerating voltage. It is the magnitude of the deflection voltage. It is the electrode plate spacing. The total length of the electromagnetic field. Let be the length of the electric field. The distance traveled away from the electromagnetic field is q, where q is the charge of the cluster ion and m is the charge of the cluster ion.

[0043] Table 1. Cluster parameters passing through the 2mm diameter aperture.

[0044] After screening, the beam current range can be obtained based on the size distribution of the clusters.

[0045] Table 2 Beam Range for Wide / Narrow Size Windows

[0046] Therefore, the wide screening window mode can maintain a high effective beam current, making it suitable for rapid dose accumulation in the early stages of processing; while the narrow screening window mode reduces the beam current, it improves the consistency of cluster size, making it suitable for later finishing. This current estimation result can be further used for dose-time conversion to determine the processing time for the wide screening window stage and the timing for switching to the narrow screening window stage.

[0047] In some embodiments, step S102 includes the following sub-steps for simulating the evolution of the surface morphology to be processed: Obtain the initial morphological parameters of the surface to be processed; Determine the cluster ion processing parameters, the cluster size range corresponding to wide and narrow screening windows, and the beam current; Based on the initial morphology parameters, the cluster ion processing parameters, the cluster size range corresponding to the wide and narrow screening windows, and the beam current, the morphology evolution of the surface to be processed is simulated.

[0048] This application determines the dose required to switch from a wide to a narrow screening window through surface morphology evolution simulation. First, an initial random roughness morphology of the surface to be processed is established, and process parameters such as cluster size distribution, beam energy, and bombardment dose step size in the wide screening window mode are input. The surface morphology evolution process under the action of a gas cluster ion beam is simulated. After each dose step, the current surface height matrix is ​​extracted, and the corresponding root mean square roughness value (RMS) is calculated, thus obtaining the following... Figure 5 The RMS curves as a function of bombardment dose are shown, along with the surface morphology evolution results at different doses.

[0049] like Figure 6 As shown, in the initial stage of processing, the surface exhibits significant undulations. The clustered beam under a wide screening window can rapidly weaken the large-scale peak-valley structure, and the RMS value decreases rapidly with increasing dose. As the bombardment dose continues to increase, the surface morphology gradually becomes smoother, and the residual undulations mainly manifest as small-scale random rough structures. At this point, when processing with a wide screening window continues, the reduction in RMS value per unit dose is significantly reduced, and the RMS curve gradually flattens. Therefore, the point where the RMS rate of decrease slows down can be used as the criterion for entering the narrow screening window refinement stage.

[0050] In some embodiments, in step S104, determining the switching dose for switching from a wide screening window to a narrow screening window based on the rate of decrease of the evolution curve of the root mean square roughness value as a function of bombardment dose includes: Calculate the rate of decrease of the root mean square roughness value as a function of bombardment dose. , ; in, Indicates dose range ( , The decrease in RMS caused by a unit dose within the range, where RMS represents the root mean square roughness value; The maximum rate of decrease of the root mean square roughness (RMS) value in the evolution curve of RMS as a function of bombardment dose is: And set the descent rate threshold to α, when the following condition is met: At that time, the endpoint dose of the determined dose interval The switching dose for switching from a wide screening window to a narrow screening window is denoted as . .

[0051] in, The larger the value, the higher the flattening efficiency of the current wide screening window processing. The smaller the value, the lower the flattening rate.

[0052] In some embodiments, α can be set according to processing efficiency and final surface roughness requirements; for example, the value of α can range from 0.1 to 0.3.

[0053] In some embodiments, when at least two dose intervals satisfy: At that time, the endpoint dose of the determined dose interval Switching dose for switching from a wide screening window to a narrow screening window To avoid misjudgments caused by fluctuations at a single simulation point, the switching dose can be determined only after two or more consecutive dose intervals have met the above conditions. For example... Figure 7 As shown.

[0054] In some embodiments, calculating the switching time from the wide screening window to the narrow screening window based on the switching dose includes: The switching time from the wide filter window to the narrow filter window is calculated using the following formula: ; in, To switch time, To switch dosages, A is the surface area to be processed, q is the charge of cluster ions, and e is the elementary charge. This refers to the beam current in wide-screen window mode.

[0055] During actual processing, the system first performs pre-flattening processing in a wide filtering window mode. When the processing time reaches... Then, the electromagnetic screening structure parameters are adjusted to switch the screening window from wide window mode to narrow window mode, and the fine finishing process begins.

[0056] Using the above method, this application can determine the switching dose and switching time of the screening window based on the RMS evolution law obtained by simulation before processing, without relying on repeated verification after processing, thereby improving the predictability and process repeatability of gas cluster ion beam segmented planarization processing.

[0057] In some embodiments, the magnetic induction intensity of the upper and lower permanent magnets is 0.3T.

[0058] This application provides a pre-calibration method for the switching time of the screening window in the segmented planarization process of gas clusters using an ion beam. This method regulates the cluster size distribution entering the processing area through an electromagnetic screening structure and determines the dose and time for switching from a wide screening window to a narrow screening window before processing, thereby achieving efficient pre-planarization of clusters with a wide size range and fine-tuning of clusters with a narrow size range.

[0059] In this application, the electromagnetic sieving structure has a wide sieving window mode and a narrow sieving window mode. The wide sieving window mode is used in the initial stage of processing, allowing effective clusters within a wider size range to pass through while eliminating monatomic ions, small-sized clusters, and other non-target particles. The narrow sieving window mode is used in the later stage of processing, making the size range of passing clusters more concentrated. In actual processing, the wide sieving window mode is first used for pre-planarization. When the processing reaches the predetermined switching dose or switching time, the electromagnetic sieving structure parameters are adjusted to switch to the narrow sieving window mode, and fine finishing processing continues.

[0060] The switching dose and switching time in this application are determined by pre-processing simulation and beam parameter calculation, without relying on repeated verification after processing. This method improves the predictability, repeatability, and process efficiency of segmented planarization of gas cluster ion beams. This application can be applied to ultra-smooth processing of high-end optical components, semiconductor substrate surface treatment, precision thin film substrate modification, X-ray mirror processing, and other precision surface processing scenarios requiring high-efficiency pre-planarization.

[0061] This application utilizes ion trajectory simulation, surface morphology evolution simulation, and RMS decline rate criteria to pre-calibrate the dose and switching time for transitioning from a wide to a narrow screening window before processing. This method eliminates the need for downtime sampling or repeated post-processing verification, directly linking screening structure parameters, beam parameters, and surface morphology evolution to calculate and determine the switching timing for segmented planarization processing. This pre-processing screening window switching time calibration, used to guide actual segmented planarization processing decisions, is a feature not yet available in other methods relying on experience or detection feedback.

[0062] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0063] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for pre-calibrating the switching time of the screening window in cluster ion planarization processing, characterized in that, Includes the following steps: The evolution of the surface morphology to be processed is simulated to obtain the evolution results of the surface morphology to be processed with the bombardment dose under the processing condition of wide screening window, and the root mean square roughness value of the surface to be processed under different bombardment doses is calculated to obtain the evolution curve of the root mean square roughness value with the bombardment dose. The switching dose for switching from a wide screening window to a narrow screening window is determined based on the rate of decrease of the root mean square roughness value as a function of bombardment dose. The switching time from the wide screening window to the narrow screening window is calculated based on the switching dose.

2. The method according to claim 1, characterized in that, The wide screening window allows effective cluster ions within a first size range to pass through; the narrow screening window allows effective cluster ions within a second size range to pass through, the first size range including the second size range.

3. The method according to claim 1, characterized in that, The simulation of the surface morphology evolution to be processed includes: Obtain the initial morphological parameters of the surface to be processed; Determine the cluster ion processing parameters, the cluster size range corresponding to wide and narrow screening windows, and the beam current; Based on the initial morphology parameters, the cluster ion processing parameters, the cluster size range corresponding to the wide and narrow screening windows, and the beam current, the morphology evolution of the surface to be processed is simulated.

4. The method according to claim 1, characterized in that, The method for determining the switching dose from a wide screening window to a narrow screening window based on the rate of decrease of the root mean square roughness value as a function of bombardment dose includes: Calculate the rate of decrease of the root mean square roughness value as a function of bombardment dose. , ； in, Indicates dose range ( , The decrease in RMS caused by a unit dose within the range, where RMS represents the root mean square roughness value; The maximum rate of decrease of the root mean square roughness (RMS) value in the evolution curve of RMS as a function of bombardment dose is: And set the descent rate threshold to α, when the following condition is met: At that time, the endpoint dose of the determined dose interval The switching dose for switching from a wide screening window to a narrow screening window is denoted as . .

5. The method according to claim 4, characterized in that, The value of α ranges from 0.1 to 0.

3.

6. The method according to claim 4, characterized in that, When at least two dose intervals are satisfied: At that time, the endpoint dose of the determined dose interval Switching dose for switching from a wide screening window to a narrow screening window .

7. The method according to claim 4, characterized in that, Based on the switching dose, the switching time from the wide screening window to the narrow screening window is calculated, including: The switching time from the wide filter window to the narrow filter window is calculated using the following formula: ； in, To switch time, To switch dosages, A is the surface area to be processed, q is the charge of cluster ions, and e is the elementary charge. This refers to the beam current in wide-screen window mode.

8. The method according to claim 1, characterized in that, The wide and narrow screening windows are formed by an electromagnetic screening structure, which includes upper and lower permanent magnets and an electrode plate disposed between the upper and lower permanent magnets. By adjusting the voltage applied to the electrode plate, the deflection trajectory of cluster ions under the combined action of magnetic and electric fields is changed, thereby adjusting the size range of cluster ions and the width of the screening window.

9. The method according to claim 8, characterized in that, The deflection range of cluster ions in the y-direction within the electromagnetic sieving structure satisfies the following formula: ； Where B is the magnetic flux density of the upper and lower permanent magnets. It is the magnitude of the accelerating voltage. It is the magnitude of the deflection voltage. It is the electrode plate spacing. The total length of the electromagnetic field. Let be the length of the electric field. The distance traveled away from the electromagnetic field is q, where q is the charge of the cluster ion and m is the charge of the cluster ion.

10. The method according to claim 8, characterized in that, The magnetic induction intensity of the upper and lower permanent magnets is 0.3T.

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