Method for cleaning micro-nano particles based on laser plasma in air environment

Abstract

The present application relates to a method for cleaning micro-nano particles in an air environment based on laser plasma, the method comprising: obtaining the particle diameter and particle position of the particle to be cleaned; the particle position represents the position of the particle to be cleaned in the substrate to be cleaned; determining a target force angle corresponding to the particle to be cleaned based on the mapping relationship between the particle diameter and a predetermined particle diameter and force angle; the target force angle is the angle between the explosion point of the laser-generated plasma and the particle position of the particle to be cleaned; determining the laser irradiation direction based on the target force angle and the particle position, emitting the laser in the irradiation direction, and cleaning the particle to be cleaned. This method can improve the cleaning effect and efficiency of the particles.

Description

Technical Field

[0001] The present application relates to the field of laser cleaning technology, and in particular to a method, apparatus, computer equipment, storage medium, and computer program product for cleaning micro-nano particles in an air environment based on laser plasma. Background Art

[0002] Laser plasma cleaning utilizes laser-generated plasma, where active substances in the plasma react physically or chemically with the surface of the product to achieve cleaning results. Compared to traditional laser cleaning, plasma shockwave removal offers several advantages, including high efficiency, environmental friendliness, and minimal substrate damage, making it a growing research hotspot.

[0003] Currently, research on laser plasma cleaning methods focuses on the forces acting on particles during removal and the effects after removal, while there is less research on the removal objects - the "particles" themselves. Therefore, the factors considered in the cleaning methods based on existing research results are relatively limited. In particular, there is less research on the phase change, evolution and removal laws of particles under the action of laser plasma, making it difficult to guarantee the cleaning effect of particles. Summary of the Invention

[0004] Based on this, it is necessary to provide a method, device, computer equipment, computer-readable storage medium and computer program product for cleaning micro-nano particles based on laser plasma in an air environment to address the technical problem that the above method is difficult to ensure the cleaning effect of particles.

[0005] In a first aspect, the present application provides a method for cleaning micro-nano particles in an air environment based on laser plasma. The method comprises:

[0006] Obtaining the particle diameter and particle position of the particles to be cleaned; the particle position represents the position of the particles to be cleaned in the substrate to be cleaned;

[0007] Determining a target force angle corresponding to the particles to be cleaned based on the particle diameter and a predetermined mapping relationship between the particle diameter and the force angle; the target force angle is the angle between the explosion point position of the plasma generated by the laser and the particle position of the particles to be cleaned;

[0008] The irradiation direction of the laser is determined according to the target force angle and the position of the particles, and the laser is emitted according to the irradiation direction to clean the particles to be cleaned.

[0009] In one embodiment, the mapping relationship between the particle diameter and the force angle includes a plurality of particle diameter intervals, and each particle diameter interval has a corresponding force angle region;

[0010] The step of determining a target force angle corresponding to the particles to be cleaned according to the particle diameter and a predetermined mapping relationship between the particle diameter and the force angle includes:

[0011] Determining a target particle diameter interval corresponding to the particle diameter from a plurality of particle diameter intervals included in the mapping relationship;

[0012] In the force angle region corresponding to the target particle diameter range, a force angle is selected as the target force angle corresponding to the particles to be cleaned.

[0013] In one embodiment, the mapping relationship between the particle diameter and the force angle is determined by:

[0014] Constructing a simulation model of a sample substrate and sample particles, and determining a plurality of target influencing factors affecting particle evolution and removal characteristics; wherein the sample particles are established on the sample substrate; the target influencing factors include plasma shock wave stress and particle diameter;

[0015] Taking each target influencing factor as a variable, the cleaning simulation of the sample particles is performed to obtain the relationship between the degree of crushing of the sample particles, the stress intensity, and the force angle and the particle diameter;

[0016] Based on the relationship diagram, the mapping relationship between the particle diameter and the force angle is analyzed and obtained.

[0017] In one embodiment, after analyzing and obtaining the mapping relationship between the particle diameter and the force angle based on the relationship graph, the method further includes:

[0018] Obtaining an experimental substrate and experimental particles, wherein the experimental particles are disposed on the experimental substrate;

[0019] Performing a cleaning experiment on the experimental particles on the experimental substrate using an experimental device to obtain electron scanning electron microscope images of the experimental particles in different force angle areas;

[0020] Performing energy spectrum analysis on the experimental particles before and after cleaning to obtain an energy spectrum diagram of the experimental particles;

[0021] Based on the electron scanning electron microscope image and the energy spectrum diagram, the mapping relationship between the particle diameter and the force angle is verified.

[0022] In one embodiment, the determining of multiple target influencing factors affecting particle evolution and removal characteristics includes:

[0023] Identify multiple candidate influencing factors that influence particle evolution and removal characteristics;

[0024] Simulating the phase change / fragmentation of the sample particles under the influence of each candidate influencing factor to obtain a phase change / fragmentation image corresponding to each candidate influencing factor;

[0025] Based on the phase change / fragmentation image corresponding to each candidate influencing factor, a plurality of target influencing factors affecting particle evolution and removal characteristics are determined from the plurality of candidate influencing factors.

[0026] In one embodiment, the determining of multiple target influencing factors affecting particle evolution and removal characteristics from the multiple candidate influencing factors based on the phase change / fragmentation image corresponding to each candidate influencing factor includes:

[0027] Obtaining the transmission pressure relationship of the shock wave, the wavefront relationship of the shock wave, and the relationship between the yield stress and the particle diameter;

[0028] Based on the phase change / fragmentation image diagrams corresponding to the candidate influencing factors, the transmission pressure relationship, the wavefront relationship, and the relationship between the yield stress and the particle diameter, multiple target influencing factors that affect the particle evolution and removal characteristics are determined from the multiple candidate influencing factors.

[0029] In a second aspect, the present application also provides a device for cleaning micro-nano particles in an air environment based on laser plasma. The device comprises:

[0030] An acquisition module, configured to acquire the particle diameter and particle position of the particles to be cleaned; the particle position indicates the position of the particles to be cleaned in the substrate to be cleaned;

[0031] a determination module, configured to determine a target force angle corresponding to the particles to be cleaned based on the particle diameter and a predetermined mapping relationship between the particle diameter and the force angle; the target force angle being the angle between the explosion point of the plasma generated by the laser and the particle position of the particles to be cleaned;

[0032] The cleaning module is used to determine the irradiation direction of the laser according to the target force angle and the position of the particle, and emit the laser according to the irradiation direction to clean the particles to be cleaned.

[0033] In a third aspect, the present application further provides a computer device. The computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are performed:

[0034] Obtaining the particle diameter and particle position of the particles to be cleaned; the particle position represents the position of the particles to be cleaned in the substrate to be cleaned;

[0035] Determining a target force angle corresponding to the particles to be cleaned based on the particle diameter and a predetermined mapping relationship between the particle diameter and the force angle; the target force angle is the angle between the explosion point position of the plasma generated by the laser and the particle position of the particles to be cleaned;

[0036] The irradiation direction of the laser is determined according to the target force angle and the position of the particles, and the laser is emitted according to the irradiation direction to clean the particles to be cleaned.

[0037] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the following steps:

[0038] Obtaining the particle diameter and particle position of the particles to be cleaned; the particle position represents the position of the particles to be cleaned in the substrate to be cleaned;

[0039] Determining a target force angle corresponding to the particles to be cleaned based on the particle diameter and a predetermined mapping relationship between the particle diameter and the force angle; the target force angle is the angle between the explosion point position of the plasma generated by the laser and the particle position of the particles to be cleaned;

[0040] The irradiation direction of the laser is determined according to the target force angle and the position of the particles, and the laser is emitted according to the irradiation direction to clean the particles to be cleaned.

[0041] In a fifth aspect, the present application further provides a computer program product. The computer program product includes a computer program that, when executed by a processor, implements the following steps:

[0042] Obtaining the particle diameter and particle position of the particles to be cleaned; the particle position represents the position of the particles to be cleaned in the substrate to be cleaned;

[0043] Determining a target force angle corresponding to the particles to be cleaned based on the particle diameter and a predetermined mapping relationship between the particle diameter and the force angle; the target force angle is the angle between the explosion point position of the plasma generated by the laser and the particle position of the particles to be cleaned;

[0044] The irradiation direction of the laser is determined according to the target force angle and the position of the particles, and the laser is emitted according to the irradiation direction to clean the particles to be cleaned.

[0045] The above-mentioned method, device, computer equipment, storage medium and computer program product for cleaning micro-nano particles in an air environment based on laser plasma first obtains the particle diameter and particle position of the particle to be cleaned, and determines the target force angle corresponding to the particle to be cleaned based on the particle diameter and the mapping relationship between the predetermined particle diameter and the force angle. Finally, the irradiation direction of the laser is determined based on the target force angle and the particle position, and the laser is emitted in the irradiation direction to clean the particle to be cleaned. This method takes into account the influence of the particle diameter and particle position on the particle cleaning effect. Therefore, it is proposed to determine the target force angle of the particle based on the particle diameter before cleaning. The target force angle is the optimal angle to ensure the particle cleaning effect. Therefore, the laser is emitted in the irradiation direction determined by the target force angle and the particle position to clean the particles to be cleaned, which can improve the cleaning effect of the particles to be cleaned. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 1 is a flow chart of a method for cleaning micro-nanoparticles in an air environment based on laser plasma in one embodiment;

[0047] Figure 2 Flowchart of the steps for determining the mapping relationship between particle diameter and force angle in one embodiment;

[0048] Figure 3 is a graph showing the relationship between the degree of crushing, stress intensity, stress angle, and particle diameter of sample particles in one embodiment;

[0049] Figure 4 Schematic diagram of distribution results obtained by combining analysis of force angles and particle sizes, force on particles, and degree of particle breakage in one embodiment;

[0050] Figure 5 A schematic diagram of a test device in one embodiment;

[0051] Figure 6.1 This is a scanning electron microscope image of the 0-30° region in one embodiment;

[0052] Figure 6.2 This is a scanning electron microscope image of the 30-45° region in one embodiment;

[0053] Figure 6.3 This is a scanning electron microscope image of the 45-60° region in one embodiment;

[0054] Figure 7 is an energy spectrum diagram of the surface of an experimental particle in one embodiment;

[0055] Figure 8 A comparison diagram of phase change / fragmentation images of shock wave stress and temperature when the force angle is 45° in one embodiment;

[0056] Figure 9 A diagram showing the influence of the force angle on the stress intensity and the degree of crushing in one embodiment;

[0057] Figure 10 This is a fragmentation image corresponding to the particle diameter when the force angle is 45° in one embodiment;

[0058] Figure 11 A schematic diagram illustrating shock wave characteristics in one embodiment;

[0059] Figure 12 is a schematic diagram for characterizing particle characteristics in one embodiment;

[0060] Figure 13 FIG1 is a block diagram of a device for cleaning micro-nano particles in an air environment based on laser plasma in one embodiment;

[0061] Figure 14 FIG. 1 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0063] Currently, laser plasma cleaning technology has reached a relatively mature stage. Compared with traditional laser cleaning technology, plasma shock wave removal technology has many advantages, such as high efficiency, environmental protection, and less damage to the substrate. Therefore, it has become a research hotspot. The research ideas and results of using laser plasma shock wave (LSC) to solve the problem of particle removal at home and abroad can be divided into three categories:

[0064] The first category is the removal mechanism, which includes the early three different removal methods of bouncing, sliding, and rolling, as well as the later particle jumping removal method.

[0065] The second category is the characteristics of the plasma's spatial shock wave and its impact on the removal effect.

[0066] The third category is to conduct theoretical and experimental analysis on the thermodynamic effects and phase change characteristics of particles under the action of shock waves, and then obtain the effect of particle removal.

[0067] These studies have explored and summarized the principles, mechanisms, and efficiency of laser plasma shock waves (LSC), and have demonstrated the feasibility and operability of the method both theoretically and experimentally. However, the focus has been on the forces exerted during removal and the effects after removal. There has been less research on the particles themselves—the particles being removed. Although there is currently research on the phase transition of particles under thermal effects, this research has focused on theory and lacks a unified and scientific explanation of the specific particle size and the location where the particles are subjected to force. By fully explaining and studying the forces and heat exerted on particles under different conditions, we can understand the phase transition process of particles, the particle removal mechanism, and the removal effects of particles of different sizes and in different regions, thereby forming a comprehensive explanation and analysis of LSC technology.

[0068] To address these issues, this application presents a comprehensive particle removal process through a decomposition and analysis of the physicochemical processes of plasma particle removal, coupled with verification of the distribution of substrate residues after laser removal. Furthermore, by analyzing the removal process for particles of varying sizes and distributions, we can more intuitively understand the particle movement during removal and provide thresholds for particle phase evolution, fragmentation, and melting, providing a reference for removing particles of varying sizes and locations.

[0069] In one embodiment, Figure 1 As shown, a method for cleaning micro-nanoparticles based on laser plasma in an air environment is provided. This embodiment uses the method applied to a terminal as an example. It can be understood that the method can also be applied to a server, and can also be applied to a system including a terminal and a server, and is implemented through the interaction between the terminal and the server. Among them, the terminal can be but is not limited to various personal computers, laptops, smart phones, tablets, Internet of Things devices and portable wearable devices. The Internet of Things devices can be smart speakers, smart TVs, smart air conditioners, smart car-mounted devices, etc. Portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc. The server can be implemented as an independent server or a server cluster composed of multiple servers. In this embodiment, the method includes the following steps:

[0070] Step S110 , obtaining the particle diameter and particle position of the particles to be cleaned; the particle position indicates the position of the particles to be cleaned in the substrate to be cleaned.

[0071] The particles to be cleaned may be micro-nano particles.

[0072] In specific implementations, the particle diameter and particle position affect the particle removal characteristics. Therefore, in order to improve the particle removal effect, before cleaning the particles to be cleaned, the particle diameter and particle position of the particles to be cleaned can be obtained first, so that the cleaning method that can improve the removal effect of the particles to be cleaned can be selected based on the particle diameter and particle position.

[0073] Step S120, determining the target force angle corresponding to the particles to be cleaned based on the particle diameter and the predetermined mapping relationship between the particle diameter and the force angle; the target force angle is the angle between the explosion point position of the plasma generated by the laser and the particle position of the particles to be cleaned.

[0074] The explosion point of the plasma is located directly above the substrate to be cleaned, specifically 3 mm above the substrate to be cleaned.

[0075] The target force angle can be understood as the optimal angle for removing the particles to be cleaned, and the removal effect of the particles to be cleaned is best at this target force angle.

[0076] In a specific implementation, the mapping relationship between particle diameter and force angle may include multiple particle diameter intervals, each particle diameter interval having a corresponding force angle region. After determining the particle diameter of the particle to be cleaned, a target particle diameter interval corresponding to the particle diameter may be determined from the multiple particle diameter intervals. Further, a force angle may be selected from the force angle region corresponding to the target particle diameter interval as the target force angle corresponding to the particle to be cleaned.

[0077] Step S130 , determining the irradiation direction of the laser according to the target force angle and the particle position, and emitting the laser in the irradiation direction to clean the particles to be cleaned.

[0078] In practice, micro-nanoparticles are cleaned by emitting a laser toward the substrate to be cleaned. The laser generates a plasma, which explodes directly above the substrate, generating shock waves in different directions that act on each particle on the substrate to be cleaned, effectively removing each particle. Therefore, after determining the target force angle and particle position, the location of the plasma explosion point can be determined based on the target force angle and particle position. The laser irradiation direction is then determined based on the location of the plasma explosion point. Finally, the laser is fired in this irradiation direction to remove the particles.

[0079] In the above-mentioned method for cleaning micro-nanoparticles in an air environment based on laser plasma, the particle diameter and particle position of the particle to be cleaned are first obtained. The target force angle corresponding to the particle to be cleaned is determined based on the particle diameter and the mapping relationship between the predetermined particle diameter and force angle. Finally, the laser irradiation direction is determined based on the target force angle and the particle position, and the laser is emitted in the irradiation direction to clean the particle to be cleaned. This method takes into account the influence of particle diameter and particle position on the particle cleaning effect. Therefore, before cleaning, it is proposed to pre-determine the target force angle of the particle based on the particle diameter. The target force angle is the optimal angle to ensure the particle cleaning effect. Therefore, the cleaning effect of the particle to be cleaned can be improved by emitting laser light in the irradiation direction determined by the target force angle and particle position.

[0080] In an exemplary embodiment, the mapping relationship between particle diameter and force angle includes multiple particle diameter intervals, each particle diameter interval having a corresponding force angle region. Correspondingly, in the above step S120, the target force angle corresponding to the particles to be cleaned is determined based on the particle diameter and the predetermined mapping relationship between the particle diameter and the force angle, which can be achieved by the following steps:

[0081] Step S121, determining a target particle diameter interval corresponding to the particle diameter from a plurality of particle diameter intervals included in the mapping relationship;

[0082] Step S122 : selecting a force angle in the force angle region corresponding to the target particle diameter range as a target force angle corresponding to the particles to be cleaned.

[0083] The force angle region corresponding to each particle diameter interval is the optimal angle region for the particle removal effect in the particle diameter interval.

[0084] Specifically, the mapping relationship includes multiple particle diameter intervals and the corresponding force angle regions of each particle diameter interval can be: the force angle region for d>500nm is 30-45°; the force angle region for d≤500nm is 45-60°, where d represents the particle diameter.

[0085] In practical applications, assuming that the particle diameter of the particles to be cleaned is 300nm, it can be determined that the target particle diameter range corresponding to the particles to be cleaned is d≤500nm, and a force angle is selected from the force angle range of 45~60° corresponding to the target particle diameter range, for example 50°, then the target force angle corresponding to the particles to be cleaned can be 50°.

[0086] In this embodiment, by setting multiple particle diameter intervals and setting a corresponding optimal force angle area for each particle diameter interval, the target force angle corresponding to any particle to be cleaned can be determined in advance, and then a laser is emitted to the particle to be cleaned based on this target force angle for cleaning. Since the irradiation direction of the laser corresponds to the optimal force angle of the particle to be cleaned, the cleaning effect of the particle to be cleaned can be improved.

[0087] In an exemplary embodiment, Figure 2 As shown, the process of determining the mapping relationship between particle diameter and force angle may include:

[0088] Step S210, constructing a simulation model of the sample substrate and sample particles, and determining multiple target influencing factors affecting particle evolution and removal characteristics; wherein the sample particles are established on the sample substrate; the target influencing factors include plasma shock wave stress and particle diameter.

[0089] In this step, the simulation model is a finite element model, which can be constructed using finite element software to analyze the phase change of the particles.

[0090] For example, the sample substrate can be a Si (silicon) substrate, and the sample particles can be Al (aluminum) particles. During the construction process, the Si substrate is first constructed. The Si substrate measures 50 μm × 50 μm × 30 μm, with the bottom surface set as the fixed point. Al particles are then created on the Si substrate. The Al particles have diameters of 50 nm, 75 nm, 100 nm, 200 nm, 500 nm, and 1000 nm.

[0091] Afterwards, a load may be applied to the simulation model for cleaning simulation. For example, the load may be applied by applying a compressive stress of 22 MPa and a temperature load of 1000 K to the upper surface of the particle. The remaining parameters are given in Table 1 below.

[0092] Table 1 Related parameters of Si substrate and Al particles

[0093]

[0094] In addition, since there are multiple factors that affect the particle evolution and removal characteristics, but the degree of influence of each factor on the particle evolution and removal characteristics is different, it is necessary to determine the factors that have a relatively greater impact on the particle evolution and removal characteristics as target influencing factors.

[0095] In step S220 , a cleaning simulation is performed on the sample particles with each target influencing factor as a variable to obtain a relationship diagram between the degree of crushing of the sample particles, the stress intensity, and the force angle and the particle diameter.

[0096] In this step, since the various target influencing factors are intertwined, a comprehensive analysis of the plasma shock wave stress and particle diameter as target influencing factors is required. Specifically, the plasma shock wave stress and particle diameter can be used as variables for simulation.

[0097] refer to Figure 3 , is a graph showing the relationship between the degree of crushing of sample particles, the stress intensity, the stress angle and the particle diameter in one embodiment. Figure 3 It can be seen that as the particle diameter increases, the stress and degree of crushing of particles at different force angles show basically the same trend, which is a process of first getting bigger and then getting smaller. The particle size can be roughly divided into small particles and large particles by the change in the degree of crushing. Small particles are particles with a particle size of less than 200nm. At this time, the particles basically do not break. Particles with a particle size of less than 75nm can be considered as ultra-small particles, which are the limit particle size for removal. For particles with a particle size greater than 200nm, the particles will be significantly crushed at this time. Particles greater than 200nm can be further divided into medium particles with a particle size of 200-800nm ​​and large particles / super-large particles greater than 800nm. Specifically, for medium particles with a particle size of 200-800nm, the particle crushing degree is relatively large at this time, and there is a clear trend of change with the change of particle size. For large particles / super-large particles with a particle size greater than 800nm, although the particles are obviously crushed at this time, the degree of crushing is not large and the change is not obvious.

[0098] Observing the curves at different load angles, we can also roughly divide them into three regions: the 0-30° region, the 30-45° region, and the 45-60° region. The 0-30° region and the 45-60° region share similar trends and intersect with each other, representing the first and third regions, respectively. The 30-45° region, on the other hand, is higher and has no intersection with the other curves, representing the second region. This pattern is consistent with the behavior of particles with load angle, showing that as the load angle increases, the stress and degree of particle fragmentation first increase and then decrease. This also agrees with the classification of experimental phenomena discussed later. Observing the curves, we can see that the stress magnitudes of the first and third regions are essentially the same when the particles are small. However, as the particles increase in size, the stress magnitude in the first region gradually decreases compared to the third region. This is because the stress in the third region is primarily a vertical component. As the particle size increases, the contact area with the substrate becomes significantly larger than that in the third region. This increased contact area results in a decrease in the average stress magnitude. The 0° curve in the first region is significantly lower than all other curves and is almost a horizontal line. This is because when the force is absolutely vertical, the particle shows no signs of movement, and therefore there is no friction. Therefore, the stress value on the particle is generally smaller than that at the tilt angle. Combined with the Hertz contact formula, the maximum stress value at the contact site is obtained by dividing the stress by the contact area:

[0099]

[0100] Combining this formula, we can see that the maximum stress has nothing to do with the change in particle size, so Figure 3 The curve in is a horizontal straight line.

[0101] In step S230 , based on the relationship diagram, a mapping relationship between the particle diameter and the force angle is obtained by analysis.

[0102] Specifically, according to the above classification of force angle and particle size, the force and crushing degree of the particles are analyzed and obtained. Figure 4 The distribution results shown. Figure 4 It can be seen that the degree of particle crushing shows a trend of first increasing and then decreasing, whether with the increase in the force angle or the increase in the particle size. When the particle size is around 500nm and the force angle is 45°, the degree of crushing reaches the maximum, the removal effect is the best, but the residue left behind is also the most. When the particle force angle is in the range of 45-60°, both large and small particles are removed by sliding and rolling, and the degree of damage is relatively low. For particles with a force angle of 0-30°, the degree of crushing is not high, but because they are mainly subjected to vertical forces, the removal effect is the worst and the base residue is the most.

[0103] After the above analysis, the phase change and evolution laws of particles can be divided into three regions, which corresponds exactly to the experimental phenomena in the following text.

[0104] The first region, between 0 and 30°, is where the laser-generated plasma shock wave contacts the particle. The surface temperature of the particle rises rapidly, exceeding the particle's melting point, causing a roughly 10nm-thick contact layer to melt. The temperature then drops rapidly throughout the particle, resulting in a uniform temperature within the particle and eliminating thermal stress. However, at the approximately 10nm-thick interface between the particle and the substrate, thermal stress persists due to the difference in thermal conductivity between the aluminum particle and the silicon substrate. However, this stress does not reach the particle's yield stress and therefore does not cause particle fragmentation. Vertical stress predominates, resulting in minimal horizontal friction. The central region of the particle, where the stress wave reflected from the substrate and the shock wave collide, forms a shock wave action zone. This zone, approximately 25nm thick, is dominated by central fragmentation. Within this zone, larger particles (greater than 180nm in diameter) undergo central fragmentation and melting under the high temperature and pressure, leaving a black spot in its original location. The resulting fragments scatter in the surrounding area, forming a ring-shaped band around the black spot. Small particles (less than 180nm) are largely unbroken. Some of them, close to larger particles, aggregate with the fragments of larger particles and scatter together on the black spots, forming a ring-shaped band. Some of them cluster together or bounce on the substrate and then fall back to the substrate, forming a small particle distribution area.

[0105] In the second region, between 30 and 45°, the temperature effects on the particles are similar to those in the first region. The horizontal and vertical stress components are comparable, resulting in the highest average stress and the largest damage zone. The particle's movement creates significant friction in the contact area with the substrate, creating a friction zone within the 20nm thickness of the particle's base. Simultaneously, the particle is squeezed by the shock wave from both sides, creating a shock wave zone 30nm above the surface. In this region, large particles displace on the substrate, breaking under the high frictional stress at their base, leaving residual fragments at the dark spot. Simultaneously, the vertical stress causes some fragmentation and melting at the center of the particle, leaving a fragmented residue behind the dark spot and forming a removal path. Small particles, however, break and melt at their bases under the shock wave, merging with the previously emitted fragments from the larger particle to form an extremely unstable aggregate, forming a comet head. Subsequent shock waves further disperse the particles, spreading out behind the comet head and forming a comet tail.

[0106] The third region, between 45 and 60°, experiences similar temperature effects as the previous regions. However, the horizontal component of stress gradually increases, while the vertical component decreases, resulting in a decrease in stress at the center of the particle. Particle fragmentation occurs primarily within the bottom 30nm region, with the 20nm thick region primarily affected by friction. The remaining 10nm thickness is the area of ​​impact for the shock wave. In this region, the frictional stress on large particles also increases, causing some damage at the bottom, leaving relatively coherent residue in the dark spots. Meanwhile, around the dark spots, due to the smaller vertical component, the particle center is relatively stable, resulting in less residue. Small particles, under the influence of the larger horizontal component, are removed more completely without leaving behind excessive residue.

[0107] Based on the above analysis and Figure 4 , it can be determined that the mapping relationship between particle diameter and force angle is: the force angle range for d>500nm is 30~45°; the force angle range for d≤500nm is 45~60°, where d represents the particle diameter.

[0108] In this embodiment, a simulation model of the sample substrate and sample particles is constructed to simulate the cleaning of the particles, and a relationship diagram between the degree of breakage of the sample particles, the stress intensity, and the force angle and the particle diameter is obtained. The mapping relationship between the particle diameter and the force angle is analyzed from the relationship diagram, so that for the cleaning of any particles to be cleaned, the irradiation direction of the laser cleaning can be determined in advance according to the mapping relationship to improve the cleaning effect.

[0109] In an exemplary embodiment, after analyzing and obtaining the mapping relationship between the particle diameter and the force angle based on the relationship graph in step S230, the following steps are further included:

[0110] Step S231: obtaining an experimental substrate and experimental particles, and setting the experimental particles on the experimental substrate.

[0111] Specifically, the experimental substrate and experimental particles can be prepared by ultrasonically cleaning a Si wafer in deionized water for 30 minutes, then removing and drying it. 100 nm Al particles are placed in ethanol and stirred with a magnetic stirrer for 6 hours. The cleaned Si wafer is then placed in the prepared Al-ethanol suspension and stored in a dry and ventilated area until the ethanol completely evaporates, thereby obtaining the experimental substrate and experimental particles.

[0112] S232, performing a cleaning experiment on the experimental particles on the experimental substrate using an experimental device to obtain electron scanning electron microscope images of the experimental particles in different force angle areas.

[0113] In this step, the entire substrate can be roughly divided into three regions based on the angle between the particle position and the plasma explosion point: 0-30°, 30-45°, and 45-60°. Particles at 0-30° are directly below the plasma explosion point and are primarily affected by the vertical force of the shock wave. Particles at 30-45° are outside the explosion point and are equally affected by the horizontal and vertical forces of the shock wave. Particles at 45-60° are at the outermost edge and are primarily affected by the horizontal force of the shock wave.

[0114] It should be noted that the division of the angle areas in this embodiment is based on the distribution characteristics of the substrate surface after particle removal. The distribution of substrate morphology is different in different areas. The maximum angle is 60° because the removal effect will be lost if it is expanded further to the periphery. Therefore, this is not discussed in this embodiment.

[0115] refer to Figure 5 , is a schematic diagram of an experimental device shown in an embodiment. The experiment uses laser to generate plasma to remove Al particles on a Si substrate. The laser used is a Nd:YAG pulse laser with an output wavelength of 1064nm, a pulse width of 12.4ns, and a repetition rate of 1Hz. After the pulse laser is output, it first passes through a spectrometer (splitting ratio 2:8). The power of the smaller energy part is monitored in real time by a power meter; the other part passes through a focusing lens with a focal length of 200mm to focus on the sample. The sample is placed on a three-dimensional platform, and its up and down movement is controlled by a terminal to change the distance between the sample and the plasma.

[0116] Before and after the experiment, the experimental particles can be scanned by an electron scanning electron microscope (SEM) to obtain an electron scanning electron microscope image.

[0117] S233, performing energy spectrum analysis on the experimental particles before and after cleaning to obtain an energy spectrum diagram of the experimental particles.

[0118] Specifically, the physical changes of the particles can be determined based on the electron scanning electron microscope image. In addition to physical changes, during the action of the laser plasma shock wave, the micro-nanoparticles will also undergo chemical changes before and after the plasma shock wave. Therefore, this step also proposes to perform energy spectrum analysis on the experimental particles before and after cleaning, so as to determine the chemical changes of the experimental particles before and after cleaning through the obtained energy spectrum.

[0119] It is understandable that the chemical changes of particles are mainly affected by the temperature of the shock wave. During the propagation process in the air, the particles in different regions are similarly affected by the temperature of the shock wave. Therefore, in the energy spectrum analysis of the experimental particles, the particles in the three regions can be discussed together without distinguishing the regions.

[0120] S234, based on the electron scanning electron microscopy image and energy spectrum diagram, the mapping relationship between particle diameter and force angle is verified.

[0121] Specifically, the physical changes of the particles, that is, the microscopic morphology of the particles, can be determined based on the electron scanning electron microscope image, and the chemical changes of the particles, that is, the spatial distribution of elements, can be determined based on the energy spectrum image.

[0122] (1)Reference Figure 6.1-Figure 6.3 , which are scanning electron microscope images of three areas of 0-30°, 30-45°, and 45-60° in one embodiment.

[0123] for Figure 6.1 In (a)-(f), (a) is the overall view of black spot 1; (b) and (c) are the enlarged views of black spot 1; (d) is the overall view of black spot 2; (e) and (f) are the enlarged views of black spot 2. Figure 6.1 In the region of 0 to 15° shown, by observing Figure 6.1 In (a) and (d), we can see that there are many black spots of about 500nm to 1000nm in size in these two areas, surrounded by many white particles of about 100nm to 300nm. In the SEM (scanning electron microscope) image, the more conductive parts will be darker, and the less conductive parts will be brighter; therefore, the black spots are aluminum and the white particles are aluminum oxide particles. Figure 6.1 (a) is enlarged to obtain Figure 6.1 In the areas ① and ② of Figures (b) and (c), it is observed that white particles are distributed in a ring shape with the black spot as the center. Figure 6.1 In (b), there are signs of melting in the black spot in ①. Figure 6.1 The area in (d) is enlarged to obtain Figure 6.1 (e) and (f) in the Figure 6.1 In image (f), black spots and white particles are also distributed in a ring-like pattern. Meanwhile, in region ③, a large number of extremely small particles around 100 nm are distributed. It can be seen that in the 0-30° region, larger particles (500-1000 nm) leave little more than a layer of melted debris on the substrate, with the fragments forming a ring-like pattern around their original location. Smaller particles (100-300 nm) remain largely on the substrate, with no significant changes.

[0124] for Figure 6.2 In (a)-(d), (a) is the overall picture; (b) is the enlarged picture of small particles; (c) is the enlarged picture of large particles; (d) is the picture of removing traces. Figure 6.2 In the region of 30 to 45 degrees, it can be found that Figure 6.2There are also a lot of residues and black spots of 500nm and above on the substrate in (a), but unlike the 0-30° area, the particles around the black spots are not evenly distributed, but have a relatively uniform direction. The distribution of the residues can be used to determine the direction of the shock wave removal. Figure 6.2 It can be seen from the black spots in the ① and ② areas of (c) that there are still many particle residues, and they are all at the front end of the particle removal. This shows that large particles will be displaced under the action of shock waves, but because in the initial state, the particles are subjected to compressive stress in the vertical direction after being affected by the shock wave, and there is also great friction in the horizontal direction, which makes the stress between the particles and the substrate greater. This causes the contact part between the particles and the substrate to be broken, leaving residues at the front end of the initial position, and then sliding or rolling on the substrate to remove them. Figure 6.2 Zooming in on area ③ in (b) reveals that these are not scratches, but rather a collection of small particles and fragments of broken large particles. At the front of each scratch, there is a distinct collection of particles, forming the comet's head, followed by scattered particles forming the comet's tail. This is the result of the removal of broken large particles and the gathering of smaller, less easily broken clusters of particles, forming the comet's head. The strong impact of the shock wave then disperses them again, and the fragments and small particles scatter in the direction of the shock wave, forming the comet's tail. Figure 6.2 As can be seen in (d), another difference from the 0-30° region is that there is an obvious particle removal trajectory in the figure, which shows the direction of the shock wave.

[0125] for Figure 6.3 In (a) and (b), (a) is the overall view; (b) is the enlarged view. Figure 6.3 In the 45-60° region shown, by observing Figure 6.3 In (a), it can be found that there are also μm-level black spots, but there is no obvious removal trace. In the ① area, there are particle residues at the front end of the removal. Figure 6.3 The amplification of (b) in the figure can slightly determine the direction of the shock wave, but compared with the area ② and Figure 6.2In (a), it is clearly visible that the residue is mostly intact, without too many small fragments, and there are no comet-shaped lines as seen previously. This indicates that in this area, the large particles are subject to less top-down force, and are more subject to horizontal forces. In the initial state, the particles are subject to greater static friction from the substrate, so there is more obvious fragmentation at the junction of the particles and the substrate. However, due to the smaller vertical force and the smaller stress within the particles, only the bottom of the particles are broken, leaving a whole residue at the front end of the initial position. Since there are not too many broken particles and the clusters of small particles are not obvious, the comet-shaped head cannot be formed, and there are no obvious removal marks on the substrate.

[0126] (2) In the observation of particle crushing and removal, it can be found that dendrites are formed on the surface of the particles, and the formation location is exactly in the area of ​​shock wave action. These dendrites are formed by the melting and subsequent solidification of the particles at high temperatures. This shows that the shock wave not only causes the bottom of the particle to collide with the substrate, generating a huge pressure and thus being physically crushed and moved, but also generates extremely high temperatures on the surface of the particle, causing the particle to undergo a chemical melting phase transition at high temperature.

[0127] During the laser plasma shock wave, micro-nanoparticles undergo physical changes, such as melting and fragmentation. Spectral analysis reveals that the elements in micro-nanoparticles undergo corresponding changes before and after the plasma shock wave, reflecting different reaction processes.

[0128] refer to Figure 7 , is the energy spectrum of the experimental particle surface shown in an embodiment. Figure 7 (a) is the original state of the nanoparticles, (b) is the morphology of the nanoparticles after melting and removal, and (c) is the morphology of the nanoparticles after melting and condensation. Figure 7 From the element distribution table, we can see that the experimental particles mainly contain three elements: Al, C, and O. The atomic percentage of C is 20.19%. This is because the particles will have a carbon deposition effect in the air, so there will be a certain proportion of C. Figure 7 It can be found in (b) and (c) that after the plasma shock wave acts, the nanoparticles will melt and then condense and ablate to form a cavity. Figure 7 (b) shows the morphology of the nanoparticles after melting, where the melted portion of the nanoparticle surface becomes liquid and is removed; Figure 7 As can be seen in (c), the nanoparticles now appear to be relatively rounded spheres, with some patterns on the bottom of the particles. Only after the nanoparticles are melted and then condensed will they become very regular spheres. Figure 7As can be seen in (b) and (c), the C element in the nanoparticles decreases or even disappears, while a new element, N, appears. This phenomenon occurs because the C element fully reacts with the air to form CO2, which dissipates into the air, thus largely disappearing. The N element appears because the laser plasma generated when the laser penetrates the air causes the deposition of N in the ionization process, which can also be demonstrated by the appearance of O and N linear lines in the plasma spectrum. Whether the nanoparticles are melted and then condensed or ablated to form cavities, the O content increases from the original 2.5% to 4.41% and 11.82%, respectively. Furthermore, a new element, Si, appears, indicating that the silicon substrate has also been ablated, forming silicon dioxide that adheres to the nanoparticles. Different degrees of ablation will lead to inconsistent element content.

[0129] In this embodiment, an experimental substrate and experimental particles are prepared, and the experimental particles on the experimental substrate are cleaned using experimental equipment to obtain electron scanning electron microscope images of the experimental particles corresponding to different force angle areas. At the same time, energy spectrum analysis is performed on the experimental particles before and after cleaning to obtain energy spectrum diagrams of the experimental particles. Based on the electron scanning electron microscope images and energy spectrum diagrams, the mapping relationship between the particle diameter and the force angle is verified, thereby further ensuring the accuracy and reliability of the determined mapping relationship between the particle diameter and the force angle.

[0130] In an exemplary embodiment, the multiple target influencing factors affecting particle evolution and removal characteristics determined in step S210 include:

[0131] Step S211 : determining a plurality of candidate influencing factors that affect particle evolution and removal characteristics.

[0132] Specifically, laser plasma removal mainly relies on the effect of shock waves. As a stress wave, shock waves act on particles and propagate inside the particles. After propagating to the junction of the particles and the substrate, they are reflected by the substrate and propagate repeatedly inside the particles, squeezing and pulling the particles. The high temperature brought by the shock wave causes uneven temperature distribution of the particles, making the particles prone to local cracking. The particles are squeezed by the stress wave and then broken and melted. At the same time, the degree of crushing and melting of particles of different particle sizes is also different. Therefore, for the removal of micro-nanoparticles by plasma, there are two main factors that affect the evolution and removal characteristics of the particles: 1. Plasma shock waves; 2. The particle size of the particles themselves. Among them, the factors affecting the plasma shock wave include the pressure (or stress) and temperature of the front of the shock wave. Therefore, candidate influencing factors may include shock wave stress, temperature and particle diameter.

[0133] In step S212 , the phase change / fragmentation of the sample particles under the influence of each candidate influencing factor is simulated to obtain a phase change / fragmentation image corresponding to each candidate influencing factor.

[0134] Specifically, the effects of shock waves on particles can be roughly divided into two categories: stress and temperature. Stress is the stress wave directly acting on the particles due to the shock wave, and it primarily has a physical effect; temperature is the high temperature on the shock wave front that is transmitted to the particles, and it primarily has a chemical effect. Based on the simulation model constructed in step S210, the phase change / fragmentation of the sample particles under the effects of shock wave stress and temperature can be simulated to obtain a phase change / fragmentation image corresponding to the shock wave stress and temperature. Simultaneously, the effect of particle diameter on particle evolution can be simulated. Specifically, based on the simulation model constructed in step S210, the particle size can be changed while keeping the other conditions unchanged. The 45° stress angle, where the degree of fragmentation is most severe, is selected to observe the pattern, and a phase change / fragmentation image of the effect of particle diameter on the particle is obtained.

[0135] Step S213 : Based on the phase change / fragmentation image corresponding to each candidate influencing factor, a plurality of target influencing factors affecting particle evolution and removal characteristics are determined from the plurality of candidate influencing factors.

[0136] Specifically, refer to Figure 8 , which shows a phase change / fragmentation image comparison diagram of shock wave stress and temperature when the force angle is 45°, according to an embodiment. The influence of shock wave stress and temperature on particle fragmentation is analyzed as follows:

[0137] The first is the impact of shock wave stress. When the stress wave acts on the particle at a 45° angle, such as Figure 8As shown, the force can be orthogonally decomposed into vertical and horizontal components. Simulation analysis was performed on one of these components. Observing the stress direction diagram reveals that when a particle is subjected to a vertical downward force, the stress wave propagates from the contact surface of the particle to the bottom. After reflection at the bottom, it collides with the subsequent stress wave, causing expansion and fragmentation near the center of the particle's bottom, with the direction of fragmentation from the inside out. Observing the fragmentation diagram also reveals that the particle fragments at the bottom, slightly toward the center, indicating that the particle is centrally fractured. For particles subjected to a horizontal force, the stress direction diagram shows that the force is primarily applied at the contact point between the particle and the substrate, primarily due to friction, while the remaining parts are more evenly stressed. Similarly, observing the particle fragmentation diagram reveals that the particle primarily fractures at the contact point with the substrate, indicating that the particle is bottom-fragmented. The two forces are then orthogonally combined to obtain the situation when the force is applied at a 45-degree angle. It can be seen that not only the bottom of the particle is affected by friction, but the center of the particle also has a tendency to expand outward and break. In the particle breakage diagram, the particle's broken area includes the bottom and center, and the damaged area is significantly larger than that of a single force. This shows that the particle has both central and bottom broken at this time, and the two forces will interact with each other to expand the broken area.

[0138] Next, consider the impact of shock wave temperature. Initially, as the wavefront reaches the particle surface, the temperature rapidly rises to 1000K, exceeding the particle's melting point and causing the particle surface to rapidly melt. Then, at 0.24 ns, the melting phase begins, with the particle's surface rapidly melting and removing. As heat propagates to 1.2 ns, the particle enters a thermal equilibrium phase, where the temperature rapidly decreases as it dissipates heat. Simultaneously, the temperature propagates rapidly within the particle. However, due to the different thermal conductivity between the aluminum particle and the silicon substrate, the temperature distribution is uniform throughout the particle, gradually approaching room temperature, except for a significant temperature difference at the contact point between the particle and the substrate. Thermal stress simulation of the particle using the particle's temperature distribution yields a thermal stress contour. This reveals that, due to the uniform temperature distribution within the particle and the absence of significant stress, a significant temperature difference occurs at the interface between the particle and the substrate, resulting in a higher stress of 77.2289 MPa. However, compared to the particle's yield stress of 121.5 MPa, this does not significantly impact the particle's fragmentation, indicating that thermal stress has no significant impact on the particle's phase transition.

[0139] Comparing the simulation results for stress and temperature reveals that particle fragmentation is primarily due to stress-induced fracture and cracking. Temperature, while initially causing a melting reaction on the particle surface, also plays a role in accelerating and catalyzing stress-induced fracture and cracking in subsequent reactions. Therefore, it can be seen that the primary factor in the impact of shock waves on particles is stress waves.

[0140] The above discussion discusses the case where the horizontal and vertical components are the same and the force angle is 45°. However, in the actual removal, the force direction of the particles on the substrate is related to the distribution of the particles, that is, the closer the particles are to the plasma, the smaller the force angle is, and vice versa. In order to find the difference in the force on the particles at different force angles, the simulation model was modified to set the force surface to a force with different angles to the normal. After applying the force again, the following is obtained: Figure 9 The simulation results are shown. Figure 9 The stress in the stress intensity curve is the average stress on the particles, and the degree of crushing is the ratio of the crushed area of ​​the particles to the total area of ​​the particles obtained by setting the crushing threshold. Figure 9 The curve in Figure 2 shows that as the angle of force applied to the particle increases, the average stress initially increases, reaches a maximum at 45°, and then gradually decreases. The trend in the degree of crushing generally matches this trend. This is consistent with the results of the previous analysis of the horizontal and vertical forces. Specifically, when the horizontal and vertical components of force applied to the particle are equal, the stress is maximum.

[0141] and Figure 9 The intersection of the threshold line of yield stress and the average stress is around 27.5°, which indicates that when the particle stress angle is between 0° and 27.5°, the average stress value of the particle is lower than the threshold value, that is, the degree of particle breakage is small, which is consistent with the Figure 9 The AB curve in the middle corresponds to the curve; when the particle is subjected to a force angle of 27.5-45°, the average stress on the particle is higher than the threshold and gradually increases, and the degree of particle crushing also gradually increases until it reaches the maximum at 45°, which is consistent with the Figure 9 Then, when the particle is subjected to force at an angle of 45-60°, the average stress on the particle decreases again, so the degree of crushing also gradually decreases, which is consistent with the Figure 9 The middle CD segment curve corresponds.

[0142] refer to Figure 10 , is an embodiment showing a particle diameter corresponding to a crushing image when the force angle is 45°, and a corresponding curve showing the change rule of the effect of particle diameter on stress intensity and crushing degree. The effect of particle diameter on particle crushing is analyzed as follows:

[0143] Since the effect of temperature on the change of particle size is not obvious, this embodiment focuses on the change of stress for particles of different particle sizes. Figure 10 The stress intensity curve in the figure is a fitting curve of the average stress magnitude. It can be seen from the stress intensity curve that as the particle size increases, the stress on the particle increases first and then decreases, reaching a maximum value at around 600nm. The crushing degree curve also basically conforms to this change pattern. According to the Hertz contact formula:

[0144]

[0145] Where a is the radius of the contact deformation circle; P is the applied load; R is the radius of the particle; u1, u2 and E1, E2 are the Poisson's ratio and Young's modulus of the two contacting materials, respectively. Combining this Hertzian contact formula, it can be seen that when the particle size is small, the contact area changes very little. Therefore, for particles with a particle size of less than 600 nm, as the particle size increases, the force-bearing area increases, and the total pressure increases, but the contact area of ​​the particle remains almost unchanged. As a result, the maximum stress at the bottom of the particle also increases accordingly. However, as the particle size exceeds 600 nm and increases further, although the total pressure also increases, the stress at the bottom of the particle decreases accordingly due to the more pronounced change in the contact area.

[0146] By adding the yield stress curve for comparison, it can be seen that the two curves intersect when the particle size is about 30nm, and the difference reaches the maximum at 700nm, so the crushing degree curve can be divided into three stages.

[0147] In the first stage, when the particle size is less than or equal to 30 nm, the particles will basically not break, and the shock wave only has a displacement effect on the particles.

[0148] In the second stage, the particle size is between 30nm and 700nm. The particles will be broken from the inside out under the action of the shock wave, and the pressure on the particles will increase with the increase of particle size. When the particle size reaches 700nm, the difference between the maximum stress and yield stress of the particles is the largest, and the degree of crushing is the largest at this time.

[0149] In the third stage, the difference between the maximum stress and the yield stress of particles with a diameter greater than 700 nm decreases, but the decrease is not large. This shows that when the particle size becomes larger, although the stress value becomes smaller, the yield stress of the particles also decreases as the particles become larger, so the degree of particle breakage does not change much relatively speaking.

[0150] In summary, among the three candidate influencing factors, shock wave stress, shock wave temperature, and particle diameter, shock wave temperature mainly plays the role of accelerating the catalytic stress fragmentation and cracking, and has little effect on the phase change of particles. Therefore, it can be determined that the multiple target influencing factors affecting particle evolution and removal characteristics are shock wave stress and particle diameter.

[0151] In this embodiment, the fragmentation of sample particles under the influence of various candidate influencing factors is simulated respectively, and based on the fragmentation image corresponding to each candidate influencing factor obtained by simulation, multiple target influencing factors affecting particle evolution and removal characteristics are determined from multiple candidate influencing factors, so that a comprehensive analysis of particle cleaning can be performed based only on the target influencing factors, and methods to improve the particle cleaning effect can be determined to improve the cleaning efficiency of micro-nano particles.

[0152] In an exemplary embodiment, the above-mentioned step S213, based on the phase change / fragmentation image diagram corresponding to each candidate influencing factor, determines multiple target influencing factors affecting particle evolution and removal characteristics from multiple candidate influencing factors, further includes: obtaining the transmission pressure relationship formula of the shock wave, the wavefront relationship formula of the shock wave, and the relationship formula between yield stress and particle diameter; based on the phase change / fragmentation image diagram, transmission pressure relationship formula, wavefront relationship formula and the relationship formula between yield stress and particle diameter corresponding to each candidate influencing factor, determines multiple target influencing factors affecting particle evolution and removal characteristics from multiple candidate influencing factors.

[0153] Specifically, since the candidate influencing factors affecting particle evolution and removal characteristics are shock wave stress, shock wave temperature and particle diameter, when screening the target influencing factors, it is also necessary to combine the relationship equations corresponding to each candidate factor to draw a relationship curve between the degree of particle fragmentation, the pressure exerted and each candidate influencing factor, and then combine the relationship curve and the fragmentation image diagram to screen the target influencing factors.

[0154] More specifically, the relationship expressions corresponding to the candidate factors are described as follows.

[0155] For the pressure and temperature in front of the shock wave:

[0156] According to the propagation formula of shock wave, combined with the propagation time, the transmission pressure relationship of shock wave can be obtained:

[0157]

[0158] Where γ is the specific heat capacity of air, which is taken as 4 / 3; ρ0 is the plasma density, which can be taken as 1.3; U represents the shock wave front transmission speed, which is obtained by differentiating the time t through the shock wave propagation radius; M is the maximum Mach number of the initial shock in the instantaneous stage of the shock wave. According to the transmission pressure relationship, we can get Figure 11 The pressure curve is shown in . When the shock wave travels a distance of 3 mm, the pressure on the shock wave front is approximately 22 MPa.

[0159] According to the wavefront relationship of the shock wave:

[0160]

[0161] Among them, R G is a universal constant of gas. The wavefront relationship can be drawn Figure 11 From the temperature curve shown in , it can be seen that when the shock wave is transmitted to 3mm, the shock wave temperature is about 1000K.

[0162] It should be noted that a spherical shock wave is generated after the plasma explosion, so the shock wave is transmitted in a spherical form, so its transmission distance and its transmission radius are consistent.

[0163] For particle size characteristics:

[0164] According to the Hall-Petch empirical formula of yield stress and particle size:

[0165] σ y =σ0+Δσ H-P

[0166]

[0167] The relationship between yield stress and particle diameter can be obtained:

[0168]

[0169] Where σ0 is the yield stress, σ0 is the material constant of the dislocation movement starting stress (Al = 9.8 MPa), d is the diameter of the particle, k y is the strengthening coefficient (kAl = 0.079). According to this relationship, the particle size is 1um to 50nm, and we can get Figure 12 The yield stress curve in Fig. 2 shows that the yield stress of particles increases as the particle diameter decreases. Therefore, when subjected to the same shock wave, large particles will be more easily broken after colliding with the substrate, while small particles will move and be removed from the substrate.

[0170] According to the formula of particle size and particle melting point:

[0171]

[0172] Among them, T m is the melting point of the particles, T mb is the melting point of the corresponding bulk material (Al Tmb =933.25), β is the material constant (Al β =1.14), d is the diameter of the particle. Similarly, taking the particle size as 1μm~50nm, we can get Figure 12The melting point curve in Figure 2 shows that the melting point of aluminum particles in the 50-1000 nm range shows little fluctuation, ranging from 910K to 930K. Therefore, it can be concluded that the particle size of the aluminum particles has little effect on their melting point.

[0173] In this embodiment, based on the transmission pressure relationship of the shock wave, the wavefront relationship, and the relationship between the yield stress and the particle diameter, the target influencing factors are screened according to the phase change / fragmentation image diagram corresponding to each candidate influencing factor, so as to facilitate the subsequent analysis of the relationship between the target influencing factors and particle cleaning.

[0174] This application studies the influence of the phase change evolution of micro-nano particles during laser plasma cleaning and analyzes its influence on the cleaning quality. The study found that under the high pressure and high temperature of the laser plasma shock wave, the particles will have different action areas, which can be divided into high temperature action area, stable area, shock wave action area, friction action area and thermal stress action area. These areas cause the unevenness of the phase change characteristics of the particles. The high temperature area is mainly melting, and the remaining areas are mainly broken. These distribution characteristics are affected by the angle of the shock wave. According to different angles, the cleaning area can be divided into three areas: 0-30°, 30-45°, and 45-60°. The main feature is that the degree of particle fragmentation shows a trend of first increasing and then decreasing as the force angle increases. Secondly, the spatial phase change of the particles is also affected by the particle size itself. As the particle size increases, the degree of fragmentation also shows a trend of first increasing and then decreasing. Based on the above conclusions, in practical applications, the force angle can be selected according to the particle size to be removed. For example, the optimal removal area for large particles (d>500nm) is 30-45°, and the optimal removal area for small particles (d<500nm) is 45-60°. This provides a reference and guidance for future plasma cleaning technology.

[0175] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0176] Based on the same inventive concept, embodiments of the present application also provide a device for cleaning micro-nano particles in an air environment based on laser plasma, which is used to implement the aforementioned method for cleaning micro-nano particles in an air environment based on laser plasma. The solution to the problem provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more embodiments of the device for cleaning micro-nano particles in an air environment based on laser plasma provided below can be found in the above-mentioned limitations of the method for cleaning micro-nano particles in an air environment based on laser plasma, and will not be repeated here.

[0177] In one embodiment, Figure 13 As shown, a device for cleaning micro-nano particles in an air environment based on laser plasma is provided, including: an acquisition module 1310, a determination module 1320 and a cleaning module 1330, wherein:

[0178] An acquisition module 1310 is configured to acquire the particle diameter and particle position of the particles to be cleaned; the particle position indicates the position of the particles to be cleaned in the substrate to be cleaned;

[0179] Determination module 1320, for determining a target force angle corresponding to the particles to be cleaned based on the particle diameter and a predetermined mapping relationship between the particle diameter and the force angle; the target force angle is the angle between the explosion point of the plasma generated by the laser and the particle position of the particle to be cleaned;

[0180] The cleaning module 1330 is used to determine the irradiation direction of the laser according to the target force angle and the particle position, and emit the laser according to the irradiation direction to clean the particles to be cleaned.

[0181] In one embodiment, the mapping relationship between particle diameter and force angle includes multiple particle diameter intervals, and each particle diameter interval has a corresponding force angle area; the determination module 1320 is also used to determine the target particle diameter interval corresponding to the particle diameter from the multiple particle diameter intervals included in the mapping relationship; in the force angle area corresponding to the target particle diameter interval, a force angle is selected as the target force angle corresponding to the particles to be cleaned.

[0182] In one embodiment, the device also includes a mapping relationship determination module for constructing a simulation model of a sample substrate and sample particles, and determining multiple target influencing factors that affect particle evolution and removal characteristics; the sample particles are established on the sample substrate; the target influencing factors include plasma shock wave stress and particle diameter; using each target influencing factor as a variable, the sample particles are cleaned and simulated to obtain a relationship diagram between the degree of fragmentation of the sample particles, the stress intensity, and the force angle and the particle diameter; based on the relationship diagram, the mapping relationship between the particle diameter and the force angle is analyzed and obtained.

[0183] In one embodiment, the device also includes a verification module for obtaining an experimental substrate and experimental particles, wherein the experimental particles are arranged on the experimental substrate; a cleaning experiment is performed on the experimental particles on the experimental substrate through experimental equipment to obtain electron scanning electron microscope images of the experimental particles in different force angle areas; energy spectrum analysis is performed on the experimental particles before and after cleaning to obtain an energy spectrum diagram of the experimental particles; based on the electron scanning electron microscope image and the energy spectrum diagram, the mapping relationship between the particle diameter and the force angle is verified.

[0184] In one embodiment, the mapping relationship determination module is also used to determine multiple candidate influencing factors that affect particle evolution and removal characteristics; simulate the phase change / fragmentation of sample particles under the action of each candidate influencing factor respectively to obtain a phase change / fragmentation image map corresponding to each candidate influencing factor; based on the phase change / fragmentation image map corresponding to each candidate influencing factor, determine multiple target influencing factors that affect particle evolution and removal characteristics from multiple candidate influencing factors.

[0185] In one embodiment, the mapping relationship determination module is also used to obtain the transmission pressure relationship of the shock wave, the wavefront relationship of the shock wave, and the relationship between the yield stress and the particle diameter; based on the phase change / fragmentation image diagram, the transmission pressure relationship, the wavefront relationship, and the relationship between the yield stress and the particle diameter corresponding to each candidate influencing factor, multiple target influencing factors that affect the particle evolution and removal characteristics are determined from multiple candidate influencing factors.

[0186] Each module in the aforementioned apparatus for cleaning micro-nanoparticles in an air environment using laser plasma can be implemented in whole or in part using software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in the computer device in the form of software, so that the processor can call and execute the corresponding operations of each module.

[0187] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as follows: Figure 14As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a method for cleaning micro-nanoparticles based on laser plasma in an air environment is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad provided on the computer device housing, or an external keyboard, touchpad or mouse.

[0188] Those skilled in the art will understand that Figure 14 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0189] In one embodiment, a computer device is further provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps in the above method embodiments when executing the computer program.

[0190] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0191] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0192] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with the relevant laws, regulations and standards of relevant countries and regions.

[0193] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processor involved in the various embodiments provided herein may be, but are not limited to, a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic unit, a data processing logic unit based on quantum computing, and the like.

[0194] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0195] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for cleaning micro-nano particles in an air environment based on laser plasma, characterized in that: The method comprises: Obtaining the particle diameter and particle position of the particles to be cleaned; the particle position represents the position of the particles to be cleaned in the substrate to be cleaned; Determining a target force angle corresponding to the particles to be cleaned based on the particle diameter and a predetermined mapping relationship between the particle diameter and the force angle; the force angle is the angle between a line connecting the explosion point of the plasma generated by the laser and the particle position of the particles to be cleaned and a horizontal plane; The irradiation direction of the laser is determined according to the target force angle and the position of the particles, and the laser is emitted according to the irradiation direction to clean the particles to be cleaned.

2. The method according to claim 1, characterized in that The mapping relationship between the particle diameter and the force angle includes a plurality of particle diameter intervals, each particle diameter interval having a corresponding force angle region; The step of determining a target force angle corresponding to the particles to be cleaned according to the particle diameter and a predetermined mapping relationship between the particle diameter and the force angle includes: Determining a target particle diameter interval corresponding to the particle diameter from a plurality of particle diameter intervals included in the mapping relationship; In the force angle region corresponding to the target particle diameter range, a force angle is selected as the target force angle corresponding to the particles to be cleaned.

3. The method according to claim 1, characterized in that The mapping relationship between the particle diameter and the force angle is determined by the following method: Constructing a simulation model of a sample substrate and sample particles, and determining a plurality of target influencing factors affecting particle evolution and removal characteristics; wherein the sample particles are established on the sample substrate; the target influencing factors include plasma shock wave stress and particle diameter; Taking each target influencing factor as a variable, the cleaning simulation of the sample particles is performed to obtain the relationship between the degree of crushing of the sample particles, the stress intensity, and the force angle and the particle diameter; Based on the relationship diagram, the mapping relationship between the particle diameter and the force angle is analyzed and obtained.

4. The method according to claim 3, characterized in that After analyzing and obtaining the mapping relationship between the particle diameter and the force angle based on the relationship graph, the method further includes: Obtaining an experimental substrate and experimental particles, wherein the experimental particles are disposed on the experimental substrate; Performing a cleaning experiment on the experimental particles on the experimental substrate using an experimental device to obtain electron scanning electron microscope images of the experimental particles in different force angle areas; Performing energy spectrum analysis on the experimental particles before and after cleaning to obtain an energy spectrum diagram of the experimental particles; Based on the electron scanning electron microscope image and the energy spectrum diagram, the mapping relationship between the particle diameter and the force angle is verified.

5. The method according to claim 3, characterized in that The determination of multiple target influencing factors affecting particle evolution and removal characteristics includes: Identify multiple candidate influencing factors that influence particle evolution and removal characteristics; Simulating the phase change / fragmentation of the sample particles under the influence of each candidate influencing factor to obtain a phase change / fragmentation image corresponding to each candidate influencing factor; Based on the phase change / fragmentation image corresponding to each candidate influencing factor, a plurality of target influencing factors affecting particle evolution and removal characteristics are determined from the plurality of candidate influencing factors.

6. The method according to claim 5, characterized in that The determining of a plurality of target influencing factors affecting particle evolution and removal characteristics from the plurality of candidate influencing factors based on the phase change / fragmentation image corresponding to each candidate influencing factor includes: Obtaining the transmission pressure relationship of the shock wave, the wavefront relationship of the shock wave, and the relationship between the yield stress and the particle diameter; Based on the phase change / fragmentation image diagrams corresponding to the candidate influencing factors, the transmission pressure relationship, the wavefront relationship, and the relationship between the yield stress and the particle diameter, multiple target influencing factors that affect the particle evolution and removal characteristics are determined from the multiple candidate influencing factors.

7. A device for cleaning micro-nano particles in an air environment based on laser plasma, characterized in that: The device comprises: An acquisition module, configured to acquire the particle diameter and particle position of the particles to be cleaned; the particle position indicates the position of the particles to be cleaned in the substrate to be cleaned; a determination module, configured to determine a target force angle corresponding to the particles to be cleaned based on the particle diameter and a predetermined mapping relationship between the particle diameter and the force angle; the force angle being the angle between a line connecting the explosion point of the plasma generated by the laser and the particle position of the particles to be cleaned and a horizontal plane; The cleaning module is used to determine the irradiation direction of the laser according to the target force angle and the position of the particle, and emit the laser according to the irradiation direction to clean the particles to be cleaned.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method for cleaning micro-nanoparticles in an air environment based on laser plasma are implemented as claimed in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for cleaning micro-nanoparticles in an air environment based on laser plasma are implemented as claimed in any one of claims 1 to 6.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method for cleaning micro-nano particles in an air environment based on laser plasma are realized as claimed in any one of claims 1 to 6.

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