Laser processing method, laser processing device, laser control method, and workpiece

Abstract

The application relates to a laser processing method, a laser processing device, a laser control method and a workpiece. The laser processing method comprises the following steps: splitting an incident laser beam to form a plurality of sub-beams; adjusting the optical path differences between the sub-beams so that the sub-beams reach the same processing position on a workpiece at different times; combining the sub-beams with the adjusted optical path differences onto the same optical path to form a combined laser beam; and processing the workpiece by using the combined laser beam. The method can improve the processing quality and reliability of products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser processing, in particular to a laser processing method and device, a laser control method and a workpiece. BACKGROUND

[0002] Through Glass Via (TGV) is an advanced three-dimensional packaging technology. By forming micron-scale vias in a glass substrate, vertical interconnection is achieved, and it is widely used in the fields of semiconductors, PCBs (Printed Circuit Boards), MEMS (Micro-Electro-Mechanical Systems), and microfluidics. Compared with traditional through silicon vias, TGV technology takes advantage of the high insulation, low radio frequency loss, and excellent thermal stability of glass materials, and exhibits significant advantages in high-frequency and high-integration devices, becoming one of the key solutions for future high-performance electronic packaging.

[0003] In related technologies, TGV processing is mainly based on laser-induced modification technology. First, a specific area inside the glass is selectively irradiated by a laser, causing the glass structure in the scanned area to be modified. Then, the modified glass is immersed in an etching solution. Due to the difference in etching rate between the modified and unmodified areas, the etching solution preferentially dissolves the modified part, ultimately forming the required microchannels. This method avoids the stress problems of mechanical drilling and is suitable for high-precision processing.

[0004] However, in the laser-induced modification process of related technologies, in order to ensure that the modified area meets the subsequent etching requirements, the laser intensity must be increased. The increase in laser intensity further causes abnormal taper or morphology distortion in the modified area, and may even cause cracks in the non-modified area around the modified area, thereby reducing the processing quality and reliability of the product. SUMMARY

[0005] Therefore, it is necessary to provide a laser processing method, device, laser control method, and workpiece that can improve the processing quality and reliability of the product.

[0006] In a first aspect, the present application provides a laser processing method, which comprises:

[0007] Splitting the incident laser beam to form multiple sub-beams;

[0008] Adjusting the optical path difference between each sub-beam so that each sub-beam reaches the same processing position on the workpiece at different times;

[0009] Combining each sub-beam after optical path difference adjustment to the same optical path to form a combined laser beam;

[0010] processing a workpiece using the combined laser beam.

[0011] In one embodiment, the workpiece is a light-transmitting solid workpiece.

[0012] In one embodiment, the pulse width of the incident laser beam is less than or equal to 600 fs.

[0013] In one embodiment, the method of processing a workpiece using the combined laser beam comprises:

[0014] shaping the combined laser beam to form a Bessel beam;

[0015] processing the workpiece using the combined Bessel beam.

[0016] In one embodiment, the combined laser beam is used to modify a work area on the workpiece to form a material modification area,

[0017] After forming the material modification area, the method of laser processing further comprises:

[0018] using a chemical etching process to make a via in the material modification area; or,

[0019] using a cleaving process to split the workpiece along the material modification area.

[0020] In one embodiment, the optical path difference between the sub-beams is adjusted so that the sub-beams reach the same processing location on the workpiece at different times, comprising:

[0021] adjusting the optical path difference between the sub-beams so that the sub-beams reach the same processing location on the workpiece at different times by setting a retro-reflective device in the optical path of at least one of the sub-beams.

[0022] In one embodiment, the retro-reflective device comprises at least one of a hollow corner cube mirror, a hollow roof mirror, and a hollow retro-reflector.

[0023] and / or, the retro-reflective device is connected to a displacement module, and adjusting the optical path difference between the sub-beams so that the sub-beams reach the same processing location on the workpiece at different times by setting a retro-reflective device in the optical path of at least one of the sub-beams, comprising:

[0024] adjusting the position of the retro-reflective device by the displacement module so that the sub-beams reach the same processing location on the workpiece at different times.

[0025] In one embodiment, before splitting the incident laser beam to form the plurality of sub-beams, the method further comprises:

[0026] adjusting a beam size of a cross section of the incident laser beam along the incident direction.

[0027] In one embodiment, the number of the sub-beams is two, including a first sub-beam and a second sub-beam; before the incident laser beam is split to form the multiple sub-beams, the method further comprises:

[0028] modulating a polarization direction of the incident laser beam;

[0029] splitting the incident laser beam to form the multiple sub-beams comprises:

[0030] polarization splitting the incident laser beam after the polarization direction is modulated to form the first sub-beam and the second sub-beam.

[0031] In one embodiment, the optical path difference is used to cause a time difference for the sub-beams to reach a same processing position on the substrate to be processed, and the time difference is within a time range in which the electron and exciton concentrations are higher than a preset concentration threshold.

[0032] In a second aspect, the application further provides a laser control method, and the controlled laser beam is used to process a light-transmitting solid substrate, the method comprising:

[0033] splitting the incident laser beam to form the multiple sub-beams;

[0034] adjusting an optical path difference between the sub-beams to cause the sub-beams to reach a same processing position on the substrate to be processed at different times;

[0035] combining the sub-beams after the optical path difference is adjusted to the same optical path to form a combined laser beam.

[0036] In a third aspect, the application further provides a laser processing device, comprising:

[0037] a ultra-short pulse laser, configured to emit a laser beam;

[0038] a beam splitting module, disposed in an optical path of the laser beam, configured to split the laser beam to form multiple sub-beams;

[0039] an optical path difference adjusting module, disposed on an emission side of the beam splitting module, configured to adjust an optical path difference between the sub-beams to cause the sub-beams to reach a same processing position on the substrate to be processed at different times;

[0040] a beam combining module, disposed on an emission side of the optical path difference adjusting module, configured to combine the sub-beams after the optical path difference is adjusted to the same optical path to form a combined laser beam, and the combined laser beam is used to process the substrate to be processed.

[0041] In a fourth aspect, the present application also provides a workpiece, which is processed by the laser processing method, processed by the laser beam regulated by the laser regulation method, or processed by the laser processing device.

[0042] The laser processing method, the laser processing device, the laser regulation method, and the workpiece first split the incident laser beam to form multiple sub-beams, then adjust the optical path difference between the sub-beams so that the sub-beams reach the same processing position on the workpiece at different times, and then combine the sub-beams with the adjusted optical path difference into the same optical path to form a combined laser beam, so that the sub-beams with the optical path difference can be accurately incident onto the same processing position on the workpiece at a certain time interval, and the same processing position on the workpiece is processed. This multi-pulse action mode through time modulation can realize more effective energy deposition and material modification without increasing the single-pulse energy. In this way, the modified region can meet the subsequent processing requirements, and the nonlinear effects and thermal damage risks caused by the high energy of the single-pulse action mode are avoided, and the risks of abnormal taper of the modified region or distortion of the appearance and cracks in the unmodified region are reduced. Therefore, the processing quality and reliability of the product can be significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the drawings needed to be used in the description of the embodiments of the present application or the related art will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other related drawings can be obtained by those skilled in the art without creative labor.

[0044] Figure 1 The flowchart of the laser processing method in one embodiment of the present application;

[0045] Figure 2 The structural diagram of the hollow right-angle reflector in one embodiment of the present application;

[0046] Figure 3 The structural diagram of the hollow ridge reflector in one embodiment of the present application;

[0047] Figure 4 The structural diagram of the hollow retroreflector in one embodiment of the present application;

[0048] Figure 5 The flowchart of the laser regulation method in one embodiment of the present application;

[0049] Figure 6 The structural diagram of the laser processing device in one embodiment of the present application;

[0050] Figure 7 A scene diagram for optical path difference adjustment process in one embodiment of the present application;

[0051] Figure 8 A structure diagram of a laser processing device in another embodiment of the present application;

[0052] Figure 9 A diagram of laser pulse space-time profile in one embodiment of the present application. DETAILED DESCRIPTION

[0053] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art, that the present application can be practiced without some or all of these specific details, and that the present application is not limited to the specific embodiments disclosed below. In other instances, well-known methods, procedures, components, and networks have not been described in detail as not to unnecessarily obscure aspects of the present application.

[0054] In the description of the present application, it should be understood that, if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0055] In addition, if the terms "first", "second" appear, these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features referred to. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, if the term "multiple" appears, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0056] In the present application, unless specifically defined otherwise, if there is an appearance of the terms "installation", "connection", "connection", "fixation" and the like, these terms should be interpreted in a broad sense. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically defined. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0057] In the present application, unless specifically defined otherwise, if there is an appearance of the terms "installation", "connection", "connection", "fixation" and the like, these terms should be interpreted in a broad sense. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically defined. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0058] It should be noted that if an element is referred to as "fixed to" or "disposed on" another element, it can be directly on another element or there can be a middle element. If an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in the present application are for illustrative purposes only and do not represent the only implementation.

[0059] Through Glass Via (TGV) is an advanced three-dimensional packaging technology that realizes vertical interconnection by forming micron-level through holes in glass substrates, and is widely used in semiconductor, PCB (Printed Circuit Board), MEMS (Micro-Electro-Mechanical Systems) and microfluidic fields. Compared with traditional silicon vias, TGV technology takes advantage of the high insulation, low radio frequency loss and excellent thermal stability of glass materials, and shows significant advantages in high-frequency and high-integration devices, becoming one of the key solutions for future high-performance electronic packaging.

[0060] In the related art, TGV processing is mainly based on laser-induced modification technology. First, the glass inside a specific area is selectively irradiated by a laser to modify the glass structure in the scanning area; then the modified glass is immersed in an etching solution. Due to the difference in etching rate between the modified area and the unmodified area, the etching solution preferentially dissolves the modified part, and finally the required microchannels are formed. This method avoids the stress problem of mechanical drilling and is suitable for high-precision processing.

[0061] In the related art, TGV processing is mainly based on laser-induced modification technology. First, the glass inside a specific area is selectively irradiated by a laser to modify the glass structure in the scanning area; then the modified glass is immersed in an etching solution. Due to the difference in etching rate between the modified area and the unmodified area, the etching solution preferentially dissolves the modified part, and finally the required microchannels are formed. This method avoids the stress problem of mechanical drilling and is suitable for high-precision processing.

[0062] The transparent solid substrate can refer to a material that at least allows part of the light of a specific wavelength band to pass through and is in a solid state in physical form, such as a glass substrate, a sapphire substrate, etc.

[0063] However, in order to achieve modification of glass materials in the related art, a laser beam with a smaller pulse width is usually selected. In transparent materials such as glass, since these materials are usually transparent to low-intensity light, the traditional linear absorption mechanism is very inefficient, and it is usually necessary to use a laser beam with a smaller pulse width to concentrate laser energy in a shorter period of time through extremely high peak power to trigger nonlinear effects such as multi-photon absorption, so that the laser energy can be absorbed not only on the surface but also in the material.

[0064] The process of modifying glass materials by a laser beam with a smaller pulse width is a complex multi-stage physical process. As a wide-bandgap material, glass cannot directly excite valence band electrons under the action of visible light to near-infrared laser through single-photon absorption. Multi-photon absorption can make electrons jump from the valence band to the conduction band to form initial free electrons. Subsequently, under the assistance of inverse bremsstrahlung mechanism, the number of free electrons continues to multiply through collision ionization, and when the free electron density reaches a critical value, avalanche ionization is triggered to form a high-density free electron plasma with metal-like characteristics. In addition, excitons are also formed in this process. At this time, the absorption efficiency of the material to the laser energy is significantly improved, and energy deposition and material modification can be achieved directly through optical field coupling.

[0065] However, in the case of a smaller pulse width, the duration of a single laser pulse is too short, and the concentration of free electrons and excitons has not reached the highest level before the laser pulse has finished acting, resulting in a decrease in optical-electric coupling efficiency and the modified area of the material not meeting the target requirements, such as aperture size, depth-to-diameter ratio, and processing efficiency.

[0066] In this case, the material modification processing can be achieved by increasing the peak power of the single pulse. However, on the one hand, the high peak power density of the laser beam is easy to induce nonlinear phenomena such as optical Kerr effect, filamentation and self-phase modulation, which destroys the stability of the spatial and temporal distribution of the beam, causing abnormal taper or morphology distortion of the modified region. On the other hand, the excessive energy deposition brought by the increase of the peak power of the laser beam will cause local thermal stress concentration, which will aggravate and expand the micro-crack propagation. Thus, the processing quality and reliability of the product are reduced.

[0067] Based on this, the embodiment of the present application provides a laser processing method, as shown in the figure, the method comprises the following steps S10-S40. Wherein: Figure 1

[0068] Step S10, the incident laser beam is split to form multiple sub-beams.

[0069] It should be noted that the laser processing method can be applied to glass via processing for glass substrate modification treatment, or can be applied to pre-treatment by directly acting on the inside of other light-transmitting solid substrates. For example, in one specific embodiment, the laser processing method in the present disclosure is used to process the light-transmitting solid substrate for modification processing, and then the substrate is divided into different application sizes along the modified region by using the splitting processing. In these scenarios, for materials that are difficult to achieve pre-treatment using single pulse laser, the laser processing method provided in the embodiment can be used to modulate the laser pulse into a multi-pulse sequence with optical path difference, and the same position of the substrate to be processed is processed using the multi-pulse sequence with optical path difference. In this way, the laser pulse that reaches the material first triggers a large number of free electrons and excitons, greatly improving the light absorption efficiency; then the laser pulse that reaches the material later can achieve efficient energy absorption and deposition, and finally form a more obvious material modification region, so that the aperture size, depth-diameter ratio, processing efficiency, etc. of the material modification region can meet the application requirements.

[0070] Wherein, the incident laser beam can refer to a laser beam that can be incident to the inside of the substrate to be processed and can induce modification of the substrate to be processed.

[0071] The substrate to be processed can refer to the target object directly subjected to the action of laser energy in the processing process. In the case of laser processing method applied to processing glass via, the substrate to be processed can refer to a glass substrate, or other light-transmitting solid substrates such as quartz crystal, sapphire, etc. The specific determination can be based on the application needs, and the embodiment does not limit it.

[0072] ​In an exemplary embodiment, the substrate to be processed is a light-transmitting solid substrate. It can be understood that although this embodiment is proposed based on a transparent or semi-transparent transparent solid substrate such as glass, this embodiment can be applied to the processing of a light-transmitting solid substrate when applied, but is not limited to the processing of a light-transmitting solid substrate.

[0073] In the case of a transparent solid substrate to be processed, the incident laser beam can be an ultrafast laser, i.e. the incident laser beam is an ultrashort pulse laser beam with a pulse width less than or equal to the order of picoseconds. The ultrafast laser can focus megawatt-level peak power to micrometer-level spots, so that the power density easily breaks through GW / cm2, and efficiently triggers nonlinear processes such as photon absorption.

[0074] In a transparent or semi-transparent transparent solid substrate such as glass, since these materials are generally transparent to low-intensity light, the traditional linear absorption mechanism is inefficient, and generally requires a laser beam with a smaller pulse width to concentrate laser energy in a shorter time, through extremely high peak power, to trigger nonlinear effects such as multiphoton absorption, so that the laser energy can be absorbed not only on the surface but also in the material.

[0075] In an exemplary embodiment, the pulse width of the incident laser beam is less than or equal to 600 fs. The shorter the pulse width of the laser beam, the higher the peak power it can have. By selecting an incident laser beam with a pulse width less than or equal to 600 fs and processing the substrate to be processed by the laser processing scheme provided by the present disclosure, both the required laser peak power and the required energy deposition for processing can be met.

[0076] Exemplarily, a beam splitting module can be disposed on the optical path of the incident laser beam, so that the laser beam emitted by the laser is incident to the beam splitting module, and the beam splitting module splits the incident laser beam into a plurality of sub-beams with different directions or paths.

[0077] Step S20, adjusting the optical path difference between the sub-beams so that the sub-beams reach the same processing position on the substrate to be processed at different times.

[0078] The optical path difference can refer to the difference in path length of different beams from the same light source to the same point.

[0079] Exemplarily, in order to make the sub-beams reach the substrate to be processed at different times, optical elements capable of regulating the optical propagation path can be deployed on the optical paths of part or all of the sub-beams, so that the sub-beams reach the substrate to be processed along different lengths of propagation paths after different propagation times.

[0080] The optical element capable of regulating the optical propagation path includes at least one of a mirror group, an optical delay line, or a liquid crystal phase modulator, and the present embodiment is not limited thereto. For example, a movable mirror group can be deployed in the light path of one of the sub-beams, and the propagation path of the sub-beam is lengthened by precisely controlling the position of the mirror; or a fixed-length delay line is inserted into the light path of another sub-beam.

[0081] In step S30, the sub-beams after the optical path difference adjustment are combined onto the same light path to form a combined laser beam.

[0082] For example, the beam combining module can be configured such that the sub-beams after the optical path difference adjustment are incident onto the beam combining module in sequence, and under the action of the beam combining module, the sub-beams are combined onto the same light path to form a combined laser beam, ensuring that the sub-beams with optical path differences can finally be accurately incident onto the same processing position on the substrate in a certain time interval.

[0083] In step S40, the substrate to be processed is processed using the combined laser beam.

[0084] As an example, the position of the substrate to be processed can be adjusted so that the substrate to be processed is located in the light path of the combined laser beam, and the substrate to be processed is processed using the combined laser beam.

[0085] As another example, a beam deflection element can also be disposed in the exit light path of the combined laser beam, and the combined laser beam is guided by the beam deflection element to be incident onto the substrate to be processed for processing.

[0086] In the present embodiment, the incident laser beam is first split into multiple sub-beams, and then the optical path differences between the sub-beams are adjusted so that the sub-beams reach the same processing position on the substrate at different times. Subsequently, the sub-beams after the optical path difference adjustment are combined onto the same light path to form a combined laser beam, ensuring that the sub-beams with optical path differences can finally be accurately incident onto the same processing position on the substrate in a certain time interval, and the same processing position on the substrate is processed. This multi-pulse action mode through time modulation can achieve more effective energy deposition and more effective material modification without increasing the single-pulse energy. In this way, it can not only ensure that the modified region meets the subsequent processing requirements, but also avoid the nonlinear effects and thermal damage risks caused by high energy in the single-pulse action mode, reducing the risk of abnormal taper or morphology distortion of the modified region and cracks in the unmodified region. Therefore, the processing quality and reliability of the product can be significantly improved.

[0087] In an exemplary embodiment, the substrate to be processed is processed using the combined laser beam, comprising:

[0088] The combined laser beam is shaped to form a Bessel beam; the Bessel beam is used to process the substrate to be processed.

[0089] The Bessel beam is a theoretically non-diffracting beam, and its transverse intensity distribution is described by the Bessel function. The focal depth of the Bessel beam can be more than 1000 times that of the Gaussian beam, and its energy is more concentrated in the long and narrow region at a long distance, which is more suitable for processing high aspect ratio structures. The high-intensity core region can efficiently trigger multi-photon absorption and avalanche ionization, and realize precise processing of the material inside the transparent material.

[0090] Exemplarily, a shaping module can be deployed on the optical path after beam combination, and the combined laser beam is shaped by the shaping module to form a Bessel beam, and then the Bessel beam is used to process the substrate to be processed.

[0091] In an exemplary embodiment, the combined laser beam is used to modify the processing of the to-be-processed region on the substrate to be processed to form a material modification region,

[0092] After the material modification region is formed, the laser processing method further includes:

[0093] Using chemical etching processing to make a via in the material modification region; or,

[0094] Using a fragmentation process to split the substrate to be processed along the material modification region.

[0095] Exemplarily, after the combined laser beam is formed, the combined laser beam can be focused on the to-be-processed region on the surface or inside the substrate to be processed, and the to-be-processed region is modified to form a material modification region. Compared with the unmodified region, the material has different etching rates or mechanical strengths, thereby providing selectivity for subsequent chemical etching or providing a pretreatment state for subsequent other processing.

[0096] In via processing applications, after the material modification region is formed, the laser-modified substrate to be processed can be placed in a suitable etching solution, and the etching rate difference between the material modification region and the unmodified region is used to selectively remove the material modification region, thereby forming a via structure at the material modification region.

[0097] In fragmentation processing applications, after the material modification region is formed, an external force can be applied to the substrate to be processed to guide the controlled fracture along the material modification region, thereby splitting the substrate to be processed into multiple parts.

[0098] In an exemplary embodiment, the optical path difference between each sub-beam is adjusted so that the time at which each sub-beam reaches the same processing position on the substrate to be processed is different, including:

[0099] By setting the retro-reflective device on the light path of at least one sub-beam, the optical path difference between each sub-beam is adjusted so that each sub-beam reaches the same processing position on the substrate to be processed at different times.

[0100] The retro-reflective device can refer to an optical element that can reflect incident light back in the opposite direction of the incident direction, and can include a mirror group, a hollow right-angle mirror, a hollow ridge mirror, and a hollow retro-reflector, etc.

[0101] Exemplarily, in order to make each beam of sub-beam reach the substrate to be processed at different times, the retro-reflective device can be deployed on the light path of part or all of the sub-beams, and the propagation path length of the sub-beam in the light path thereof is adjusted by the retro-reflective device, so that each sub-beam reaches the substrate to be processed along a different length of propagation path after a different propagation time.

[0102] In an exemplary embodiment, the retro-reflective device includes a hollow right-angle mirror, a hollow ridge mirror, and a hollow retro-reflector.

[0103] The hollow right-angle mirror can refer to a hollow cube corner structure composed of two mutually perpendicular reflecting surfaces. As shown in FIG. 2, the dashed line represents the direction of light propagation, and the incident light first enters one of the reflecting surfaces 202 and is reflected to the other reflecting surface 204, and after being reflected twice, it returns in the opposite direction of the incident direction. Figure 2 The hollow ridge mirror can refer to a retro-reflective optical device composed of two mutually perpendicular plane mirrors. As shown in FIG. 3, the dashed line represents the direction of light propagation, and the incident light first enters one of the mirrors 302 and is reflected to the other mirror 304, and after being reflected twice, it returns in the opposite direction of the incident direction.

[0104] Figure 3 The hollow retro-reflector can refer to a corner cube composed of three front surface mirrors. As shown in FIG. 4, the dashed line represents the direction of light propagation, and the incident light first enters one of the mirrors 402 and is reflected to the other mirror 404, and after being reflected twice, it returns in the opposite direction of the incident direction.

[0105] The hollow retro-reflector can refer to a corner cube composed of three front surface mirrors. As shown in FIG. 4, the dashed line represents the direction of light propagation, and the incident light first enters one of the mirrors 402 and is reflected to the other mirror 404, and after being reflected twice, it returns in the opposite direction of the incident direction. Figure 4 ​As shown, the dashed line represents the direction of light beam propagation, the incident light first enters one of the mirrors, is reflected to the second mirror, and then is reflected to the third mirror. After three reflections, the light is returned along the direction opposite to the incident direction. Compared with the retro-reflective device composed of two reflecting surfaces, the hollow retro-reflector composed of three reflecting surfaces has strong robustness to alignment errors and position changes. As long as the incident light can simultaneously illuminate the three reflecting surfaces, the outgoing light will be strictly parallel to the incident light, and will not be affected by the rotation or inclination of the device, and the stability of the retro-reflection is higher. In this way, in actual application, even if there is slight vibration, displacement or angle drift of the installation platform, the retro-reflector can still ensure the stability of the light path without the need for precise and tedious alignment adjustment. The retro-reflective device composed of three reflecting surfaces has little effect on the polarization state of polarized light and almost no effect on the polarization. In the case of using polarization beam splitters and polarization beam combiners, the sub-beams can maintain their own polarization states, thereby successfully combining the beams.

[0106] In an exemplary embodiment, the retro-reflective device is connected with a displacement module. The position of the retro-reflective device disposed on the light path of at least one sub-beam is adjusted by the displacement module, so that the time when each sub-beam reaches the same processing position on the substrate to be processed is different, including:

[0107] The position of the retro-reflective device disposed on the light path of at least one sub-beam is adjusted by the displacement module, so that the time when each sub-beam reaches the same processing position on the substrate to be processed is different.

[0108] The displacement module can be a mechanical device capable of driving the movement of the retro-reflective device.

[0109] In some feasible embodiments, the displacement module can include a precision motor and a precision guide rail. The displacement module can control the position of the retro-reflective device, and the retro-reflective device can be driven by the displacement module to adjust the propagation path length of the sub-beam along the guide rail, so as to assist the retro-reflective device to efficiently and accurately control the optical path of the sub-beam.

[0110] Exemplarily, in order to make each beam of sub-beam reach the substrate to be processed at different times, the retro-reflective device can be deployed on the light path of part or all of the sub-beams, and part of the retro-reflective devices can be equipped with corresponding displacement modules. The displacement module is connected with the corresponding retro-reflective device, so as to control the position of the retro-reflective device. The retro-reflective device is driven to move by the displacement module, so as to adjust the propagation path length of the sub-beam, so as to assist the retro-reflective device to efficiently and accurately control the optical path of the sub-beam. Each sub-beam reaches the substrate to be processed along different lengths of propagation path after different propagation times.

[0111] In an exemplary embodiment, before splitting the incident laser beam to form multiple sub-beams, the method further comprises:

[0112] Adjusting the beam size of the cross section of the incident laser beam along the incident direction.

[0113] Exemplarily, the beam scaling mechanism can be deployed on the light-in side of the beam splitting module, and the beam size of the cross section of the incident laser beam along the incident direction is adjusted by the beam scaling mechanism.

[0114] Wherein, the beam scaling mechanism can refer to an optical device capable of adjusting the cross-sectional area size of the laser beam along the transmission direction, which is usually used to increase or reduce the cross-sectional area of the light beam, and can include a beam expander or a beam reducer.

[0115] In an exemplary embodiment, the number of sub-beams is two, including a first sub-beam and a second sub-beam; before splitting the incident laser beam to form multiple sub-beams, the method further comprises:

[0116] Modulating the polarization direction of the incident laser beam.

[0117] In some embodiments, in applications requiring dynamic adjustment of the laser power distribution of the sub-beams, the laser power of the first sub-beam and the second sub-beam can be allocated according to the processing needs before splitting, and the polarization direction of the incident laser beam is modulated according to the laser power allocation result, and then the modulated incident laser beam is polarized and split, so that the first sub-beam and the second sub-beam that meet the processing needs can be obtained.

[0118] Although the beam splitter can split one incident laser beam into multiple sub-beams, in actual applications, it is usually chosen to be split into two beams, which is mainly based on the consideration of practicability and technical requirements. On the one hand, the optical structure and control method of the system are simpler and more reliable when split into two beams; on the other hand, controlling the two sub-beams to reach the same processing position in turn can ensure that the modified area meets the subsequent processing needs on the basis of ensuring the processing quality and reliability.

[0119] It should be noted that in application scenarios requiring more sub-beams, the present application can also generate multiple laser beams through beam splitting technology to adapt to the actual needs of different application scenarios and provide more flexible processing solutions.

[0120] Exemplarily, the laser power of the first sub-beam and the second sub-beam can be allocated according to the processing needs first, and then the target polarization direction of the incident laser beam is determined according to the laser power allocation result of the first sub-beam and the second sub-beam, and then the polarization direction of the incident laser beam is modulated to the target polarization direction.

[0121] Splitting the incident laser beam to form multiple sub-beams includes:

[0122] The polarized direction modulated incident laser beam is polarized split to form a first sub-beam and a second sub-beam.

[0123] Exemplarily, the laser beam can be modulated in the optical path or the position of the beam splitting module, so that the polarized direction modulated laser beam is incident to the polarized beam splitter, and the polarized beam splitter splits the incident laser beam into a first sub-beam and a second sub-beam according to the processing needs.

[0124] The polarized beam splitter can refer to an optical element capable of splitting or combining light incident therein based on polarization characteristics. The polarized beam splitter can separate a beam of non-polarized light or mixed polarized light into two beams of orthogonal linearly polarized light, such as P-polarized light and S-polarized light, according to the polarization direction. The polarized beam splitter can also combine two beams of orthogonal polarized light into a beam of light. The polarized beam splitter has high energy utilization. After the laser beam is incident to the deflected beam splitting module, the polarized beam splitter can almost equally distribute the entire energy of the laser beam to two sub-beams, thereby effectively reducing energy loss and ensuring subsequent modification effect.

[0125] In addition, the polarized beam splitter can also flexibly control the laser power ratio of the two sub-beams after splitting by adjusting the polarization direction of the incident laser beam. Therefore, the polarized beam splitter has a significant advantage in applications requiring dynamic adjustment of laser power distribution.

[0126] It can be understood that the beam splitting module can also use other types of laser beam splitting components without polarization function, such as ordinary cubic beam splitting mirrors or thin film beam splitting modules. Such beam splitting elements have simple structure and low cost, and can meet the application requirements without the need to adjust the laser power of the split sub-beams.

[0127] In an exemplary embodiment, the optical path difference is used to cause a time difference for each sub-beam to reach the same processing position on the substrate to be processed, and the time range is higher than the preset concentration threshold of the electron and exciton concentration.

[0128] After the laser pulse interacts with the material, the material will undergo multi-photon absorption, avalanche ionization and other effects, generating a large number of free electrons. Subsequently, the free electrons undergo a relaxation process, and at the same time, excitons are generated in the material. The higher the concentration of free electrons and excitons, the higher the light absorption efficiency. If the second laser beam is incident at the time when the concentration of free electrons and excitons is the highest, the action area can more effectively absorb light energy, thereby forming a more obvious modified area.

[0129] Therefore, the preset concentration threshold at which the free electron and exciton concentrations can reach and the light absorption efficiency can meet the requirements can be determined in advance by testing, and the time range in which the electron and exciton concentrations are higher than the preset concentration threshold is determined by testing, and then the corresponding optical path difference range is calculated according to the time range and the laser propagation speed.

[0130] Based on the same inventive concept, the embodiments of the present application also provide a laser control method. The implementation scheme for solving the problem provided by the laser control method is similar to the implementation scheme described in the above laser processing method, so the specific limitations in one or more laser control method embodiments provided below can refer to the limitations of the laser processing method described above, which will not be repeated here.

[0131] In an exemplary embodiment, as shown in Figure 5 A laser control method is provided, and the controlled laser beam is used for processing a light-transmitting solid substrate. The method includes steps 502 to 506, wherein:

[0132] Step 502: splitting the incident laser beam to form a plurality of sub-beams;

[0133] Step 504: adjusting the optical path difference between the sub-beams so that the sub-beams reach the same processing position on the light-transmitting solid substrate at different times;

[0134] Step 506: combining the sub-beams after the optical path difference adjustment to the same optical path to form a combined laser beam.

[0135] The combined laser beam can be used to process the light-transmitting solid substrate.

[0136] In an exemplary embodiment, the pulse width of the incident laser beam is less than or equal to 600 fs.

[0137] In an exemplary embodiment, after the sub-beams after the optical path difference adjustment are combined to the same optical path to form a combined laser beam, the method further includes:

[0138] Shaping the combined laser beam to form a Bessel beam.

[0139] The Bessel beam can be used to process the light-transmitting solid substrate.

[0140] In an exemplary embodiment, adjusting the optical path difference between the sub-beams so that the sub-beams reach the same processing position on the light-transmitting solid substrate at different times includes:

[0141] Adjusting the optical path difference between the sub-beams by a retroreflective device arranged in the optical path of at least one sub-beam so that the sub-beams reach the same processing position on the light-transmitting solid substrate at different times.

[0142] In an example embodiment, the retro-reflective device comprises at least one of a hollow corner-cube mirror, a hollow ridge mirror, and a hollow retro-reflector.

[0143] And / or, the retro-reflective device is connected with the displacement module, and the optical path difference between the sub-beams is adjusted by the retro-reflective device arranged on the light path of the at least one sub-beam, so that the time for the sub-beams to reach the same processing position on the substrate to be processed is different, comprising:

[0144] The position of the retro-reflective device is adjusted by the displacement module, so that the time for the sub-beams to reach the same processing position on the substrate to be processed is different.

[0145] In an example embodiment, before the incident laser beam is split to form multiple sub-beams, the method further comprises:

[0146] Adjusting the beam size of the cross section of the incident laser beam along the incident direction.

[0147] In an example embodiment, the number of sub-beams is two, comprising a first sub-beam and a second sub-beam; before the incident laser beam is split to form multiple sub-beams, the method further comprises:

[0148] Modulating the polarization direction of the incident laser beam;

[0149] Splitting the incident laser beam to form multiple sub-beams comprises:

[0150] Polarization splitting the incident laser beam modulated in the polarization direction to form the first sub-beam and the second sub-beam.

[0151] In an example embodiment, the optical path difference is used to make the time difference for the sub-beams to reach the same processing position on the substrate to be processed within a time range in which the electron and exciton concentration is higher than a preset concentration threshold.

[0152] Based on the same inventive concept, the embodiments of the present application also provide a laser processing device. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme described in the above laser processing method, so the specific limitations in one or more laser processing device embodiments provided below can refer to the limitations of the laser processing method described above, and will not be repeated here.

[0153] In an example embodiment, the embodiments of the present application also provide a laser processing device, as shown in Figure 6 The laser processing device comprises a ultra-short pulse laser 608, a beam splitting module 602, an optical path difference adjusting module 604, and a beam combining module 606, and the arrow represents the propagation direction of the laser beam.

[0154] The ultrashort pulse laser 608 can refer to a laser capable of emitting an ultrashort pulse laser beam. The ultrashort pulse laser beam can refer to a laser beam with a pulse width less than picoseconds.

[0155] The beam splitting module 602 is an optical element capable of splitting a laser beam incident therein into two or more sub-beams according to a specific ratio.

[0156] In this embodiment, the beam splitting module 602 is used to receive a laser beam and split the laser beam to form multiple sub-beams.

[0157] The optical path difference adjustment module 604 can refer to a device capable of adjusting the physical length of the propagation path of a light beam and adjusting the optical path difference between different light beams by changing the physical length of the propagation path of the light beam. The optical path difference adjustment module 604 is disposed on the light exit side of the beam splitting module 602 and on the propagation path of at least part of the sub-beams. The propagation path length of at least one of the sub-beams can be adjusted by the optical path difference adjustment module 604, so that the optical paths of the sub-beams are different, thereby controlling the time difference of the sub-beams reaching the substrate to be processed.

[0158] In some possible embodiments, the optical path difference adjustment module 604 can include a mirror group, an optical delay line, a liquid crystal phase modulator, etc., and the present disclosure does not limit the specific components of the optical path difference adjustment module 604.

[0159] In some possible embodiments, the optical path difference adjustment module 604 can be disposed on at least part of the optical paths of the sub-beams, or all of the optical paths of the sub-beams.

[0160] In some possible embodiments, the manner in which the optical path difference adjustment module 604 adjusts the optical path difference can include at least one of increasing the propagation path length and decreasing the propagation path length.

[0161] The beam combining module 606 can refer to an optical element capable of recombining multiple independently propagating light beams onto the same optical axis.

[0162] In this embodiment, the beam combining module 606 is disposed on the light exit side of the optical path difference adjustment module 604 and at the starting position where the optical paths of the sub-beams intersect, and is used to recombine the sub-beams after the optical path difference adjustment onto the same optical axis.

[0163] In some possible embodiments, when the beam splitting module 602 uses a polarization beam splitter, the beam combining module 606 can use a polarization combiner.

[0164] As an example, the laser processing device can be deployed on the laser light path between the laser 608 and the substrate to be processed, for modulating the laser beam emitted by the laser 608, and the first and second sub-beams after modulation can act on the same processing position on the substrate to be processed at a certain time interval. In the process of modulating the laser beam, the laser beam emitted by the laser 608 is first incident into the beam splitting module 602 and is split into the first sub-beam L and the second sub-beam L'; the two sub-beams enter the beam combining module 606 along different light paths, and one or both of the sub-beams can be subjected to optical path adjustment by the optical path difference adjustment module 604 before entering the beam combining module 606; the two sub-beams after optical path adjustment enter the beam combining module 606 in sequence and are combined into coaxial output, and are finally focused on the same processing position on the substrate to be processed. The sub-beam that reaches the substrate to be processed first can trigger free electrons and excitons, which can greatly improve the light absorption efficiency and achieve higher laser utilization; the sub-beam that reaches the substrate to be processed subsequently can deposit more energy and achieve more obvious material modification.

[0165] In an exemplary embodiment, the laser processing device further comprises:

[0166] A Bessel shaping module is deployed on the light output side of the beam combining module 606, for shaping the combined laser beam after beam combination to form a Bessel beam.

[0167] The Bessel shaping module can refer to an optical element for converting a traditional Gaussian beam into a Bessel beam, and the Bessel shaping module can perform phase modulation on the wavefront of the laser beam incident therein to generate a Bessel beam with no diffraction characteristics.

[0168] In an exemplary embodiment, the optical path difference adjustment module 604 comprises a high-precision displacement module and a retro-reflective device.

[0169] In an exemplary embodiment, the pulse optical path modulation device further comprises at least one high-precision displacement module, each displacement module corresponding to each optical path difference adjustment module 604, and each displacement module being connected to the corresponding optical path difference adjustment module 604 for adjusting the position of the corresponding optical path difference adjustment module 604 in the preset displacement direction to assist the optical path difference adjustment module 604 to efficiently and accurately adjust the optical path of the light path.

[0170] In an exemplary embodiment, the number of sub-beams is two, including a first sub-beam and a second sub-beam;

[0171] An anti-reflection device is deployed on the transmission optical path of the first sub-beam; the transmission optical path of the first sub-beam also includes a first reflector; through the anti-reflection device, the first reflector, and the displacement module, an optically path-adjustable first retroreflection optical path is formed on the transmission optical path of the first sub-beam.

[0172] The laser processing apparatus also includes a mirror assembly, which is used to form a second retroreflection path with a fixed optical path in the transmission optical path of the second sub-beam.

[0173] The retroreflection path can refer to the path that the light beam returns along after passing through the optical element, which is parallel to the incident direction. In other words, the retroreflection path includes two parallel but opposite light paths.

[0174] When there are two sub-beams, an optical path difference adjustment module 604 can be deployed on the transmission optical path of one of the sub-beams. That is, a retroreflector, a first reflector, and a displacement module can be deployed on the transmission optical path of the first sub-beam. An adjustable optical path can be constructed through the retroreflector, the first reflector, and the displacement module. Meanwhile, a mirror group can be deployed on the transmission optical path of the other sub-beam. That is, a mirror group can be deployed on the transmission optical path of the second sub-beam. A fixed optical path can be constructed through the mirror group.

[0175] In some feasible implementations, when the optical path lengths of the first sub-beam and the second sub-beam are equal, by constructing a first retroreflection optical path and a second retroreflection optical path, the optical paths of the first sub-beam and the second sub-beam can be made optically mirror-symmetrical. Thus, the optical path length of the first sub-beam can be adjusted simply by changing the position of the retroreflector via a displacement module, thereby quickly adjusting the optical path difference between the first and second sub-beams.

[0176] As an example, such as Figure 7 As shown, the incident laser beam emitted by the ultrashort pulse laser 702 is split into a first sub-beam and a second sub-beam by the beam splitter 704. The first sub-beam is reflected light, which is reflected by the first reflecting mirror 7063 and then incident on the retroreflector 7061. After returning along the original optical path, it is incident on the beam combiner 708. The second sub-beam is transmitted light, which is reflected by a mirror group composed of three reflecting mirrors 710 to form a retroreflection path and then incident on the beam combiner 708, where it is combined with the first sub-beam. The position of the mirror group deployed on the transmission optical path of the second sub-beam is fixed, thus the optical path length of the second sub-beam is fixed. The retroreflector 7061 deployed on the transmission optical path of the first sub-beam is connected to the displacement module 7062. By adjusting the position of the retroreflector 7061 through the displacement module 7062, the optical path length of the first sub-beam can be adjusted.

[0177] In one exemplary embodiment, the laser processing apparatus further includes a beam scaling mechanism.

[0178] The beam scaling mechanism is disposed in the light path of the laser beam emitted by the laser 608 and on the light entrance side of the beam splitting module 602, and is used to adjust the beam size of the cross section of the incident laser beam along the incident direction.

[0179] The beam scaling mechanism can refer to an optical device capable of adjusting the diameter of a laser or other light beam, including a beam expander or a beam reducer. The beam scaling mechanism is usually used to increase or reduce the cross-sectional area of the light beam. The beam scaling mechanism can change the collimation and spot size of the light beam while maintaining the beam quality, ensuring that the wavefront distortion is minimized, and can also modulate the Bessel shaping non-diffraction distance and Bessel spot size.

[0180] In an exemplary embodiment, an aperture can also be disposed on the light entrance side of the beam splitting module. The aperture blocks stray light, reduces glare and ghosting, and improves imaging quality.

[0181] In some possible implementations, the aperture can be disposed on the light exit side of the beam expander. In this way, the beam diameter can be first increased by the beam expander to reduce the divergence angle, and then the central uniform part can be intercepted by the aperture to ensure the beam quality.

[0182] In an exemplary embodiment, the beam splitting module 602 includes a polarization beam splitter, and the transmission light paths of the sub-beams are provided with a first sub-beam fine adjustment mechanism. The first sub-beam fine adjustment mechanism can be used to further finely adjust the laser power distribution of the first sub-beam and the second sub-beam after the beam splitting of the beam splitting module 602.

[0183] The first sub-beam fine adjustment mechanism is an optical component that can adjust the sub-beam laser power distribution, including at least one of a half-wave plate, a 1 / 4 wave plate, etc. When a half-wave plate is used as the first sub-beam fine adjustment mechanism, the half-wave plate can achieve continuous adjustment of the laser power distribution of each sub-beam by rotating the angle. When a 1 / 4 wave plate is used as the first sub-beam fine adjustment mechanism, the 1 / 4 wave plate can only achieve 5:5 equal power splitting of two sub-beams, and cannot dynamically adjust the laser power distribution of the sub-beams through the first sub-beam fine adjustment mechanism.

[0184] It can be understood that in a scenario where the laser power of the sub-beam does not need to be adjusted, the first sub-beam fine adjustment mechanism can not be arranged.

[0185] In some possible implementations, the first sub-beam fine adjustment mechanism is a half-wave plate.

[0186] The half-wave plate is a phase retarder based on birefringence effect, and can introduce a phase difference of π radians for two orthogonal polarization components of the incident light, thereby changing the polarization state of the incident light. By modulating the polarization direction of the laser beam incident to the beam splitter, the laser power distribution of the first and second sub-beams can be adjusted.

[0187] By arranging a half-wave plate on the incident light path of the beam splitting module 602, the polarization direction of the laser beam incident thereto can be changed by rotating the half-wave plate, thereby adjusting the proportion of the two types of polarized light with perpendicular polarization directions entering the polarization beam splitter, so that the intensity ratio of the two sub-beams output by the polarization beam splitter can be adjusted, and the adjustability of the laser power distribution can be realized.

[0188] In an exemplary embodiment, the laser processing device further comprises a second sub-beam fine adjustment mechanism arranged on the transmission light path of at least one sub-beam to adjust the laser power of the at least one sub-beam.

[0189] The second sub-beam fine adjustment mechanism can refer to an optical component capable of adjusting the sub-beam laser power distribution, including at least one of a half-wave plate, a 1 / 4 wave plate, etc. By arranging a second sub-beam fine adjustment mechanism on the light path of at least one sub-beam, the laser power of each sub-beam can be further fine-tuned, and a laser beam that meets the processing requirements can be obtained.

[0190] In the present embodiment, the laser processing device comprises a beam splitting module, an optical path difference adjustment module, and a beam combining module arranged in sequence on the light path of the laser beam. First, the single laser beam emitted by the laser is split into multiple sub-beams by the beam splitting module; then the propagation path lengths of at least part of the sub-beams are adjusted by the optical path difference adjustment module to generate optical path differences between the sub-beams; subsequently, the sub-beams with optical path differences are recombined onto the same light path by the beam combining module, ensuring that the sub-beams with optical path differences can finally be accurately incident onto the same processing position on the substrate to be processed at a certain time interval. This multi-pulse action mode through time modulation can achieve more effective energy deposition and more obvious modification of the processing site of the substrate to be processed without increasing the single-pulse energy. In this way, it can not only ensure that the modified region meets the subsequent etching requirements, but also avoid the risk of high-order nonlinear effects and thermal damage caused by high energy in the single-pulse action mode, and reduce the risk of abnormal taper or morphology distortion of the modified region and cracks in the non-modified region. Therefore, the processing quality and reliability of the product can be significantly improved.

[0191] In an exemplary embodiment, as Figure 8As shown, the laser processing device comprises a collimating expander 810, an adjustable diaphragm 812, a 1030nm polarization beam splitter 804, a 1030nm half-wave plate 8141, a dielectric mirror 816, a hollow right-angle mirror 806, a precision displacement platform 820, a polarization beam combiner 808, and a Bessel shaping module 818.

[0192] The ultra-short pulse laser 802 outputs a femtosecond pulsed laser beam at 1030nm, which is modulated to a suitable beam diameter by the collimating expander 810, and then filtered by the adjustable diaphragm 812 to remove part of the laser beam. The laser beam passing through the adjustable diaphragm is adjusted in polarization state by adjusting the rotation angle of the half-wave plate 8141, so as to adjust the laser power distribution of the two sub-beams output by the polarization beam splitter 804. The laser beam passing through the half-wave plate 8141 is split into two sub-beams by the polarization beam splitter 804, i.e., the p-polarized light and the s-polarized light. The p-polarized light passes through the mirror group composed of the half-wave plate 8142 and the three-mirror 816 in sequence, and then is incident on the polarization beam combiner 808. The mirror group composed of the three-mirror 816 is used to make the optical path of the p-polarized light completely symmetrical to that of the s-polarized light. The s-polarized light is first incident on the hollow right-angle mirror 806, which is installed on the precision displacement platform 820. The precision displacement platform 820 can drive the hollow right-angle mirror 806 to move along the arrow direction, so as to adjust the optical path of the s-polarized light according to actual needs. After the optical path of the s-polarized light is adjusted by the hollow right-angle mirror 806, the s-polarized light is incident on the polarization beam combiner 808 again through the half-wave plate 8143. After the p-polarized light and the s-polarized light pass through different lengths of propagation paths, they are combined into the same optical path by the polarization beam combiner 808 in sequence. After the p-polarized light and the s-polarized light pass through the beam combiner, they are adjusted in direction by the two-mirror 816 in sequence, and then are incident on the Bessel shaping module 818. The Bessel shaping module 818 is composed of a conical lens and a beam compression system, and can convert the ultra-short Gaussian pulse into an ultra-short micro-Bessel pulse that meets the processing requirements.

[0193] The half-wave plate 8141 before the polarization beam splitter 804 is used to adjust the laser power distribution of the two sub-beams output by the polarization beam splitter 804. The half-wave plates 8142 and 8143 after the polarization beam splitter 804 are used to further fine-tune the laser power of each sub-beam, so as to obtain a combined laser beam that meets the processing requirements.

[0194] After the above time-domain and space-domain shaping techniques are processed, the time-space profile of the laser pulse is as shown in Figure 9 Figure 9 a is the light intensity distribution of the waist position of the ultra-short micro-Bessel pulse in the spatial domain. Figure 9 ​b is the time distribution of the ultra-short micro-Bessel pulse sequence in the time domain, and the delay interval (Delay) can be adjusted by controlling the displacement of the hollow right-angle reflector 806 by the precision displacement platform 820.

[0195] Based on the same inventive concept, in one exemplary embodiment, a workpiece is provided, which is machined by a modulated laser beam, the modulated laser beam is formed by pulse modulation using the laser machining device as above, or is formed by pulse modulation using the laser machining method as above; or the workpiece is machined using the laser machining device as above.

[0196] It should be understood that, although the steps in the flowcharts involved in the above embodiments are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and these steps can be executed in other orders. Moreover, at least part of the steps in the flowcharts involved in the above embodiments can include multiple steps or stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of these steps or stages is not necessarily sequential, but can be executed in rotation or alternation with at least part of other steps or steps or stages in other steps.

[0197] The technical features of the above embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered as falling within the scope of the present application.

[0198] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A laser processing method, characterized in that, The method includes: The incident laser beam is split into multiple sub-beams; The optical path difference between each sub-beam is adjusted so that the time taken for each sub-beam to reach the same processing position on the substrate to be processed is different; the optical path difference is used to ensure that the time difference between the arrival of each sub-beam at the same processing position on the substrate to be processed is within the time range where the electron and exciton concentrations are higher than a preset concentration threshold; the preset concentration threshold is determined in advance by testing, and the time range within which the electron and exciton concentrations are higher than the preset concentration threshold is determined by testing, and the corresponding optical path difference range is calculated based on the time range and the laser propagation speed; The sub-beams, after optical path difference adjustment, are combined into the same optical path to form a combined laser beam. The substrate to be processed is processed using the combined laser beam.

2. The laser processing method according to claim 1, characterized in that, The substrate to be processed is a light-transmitting solid substrate.

3. The laser processing method according to claim 2, characterized in that, The pulse width of the incident laser beam is less than or equal to 600 fs.

4. The laser processing method according to claim 2, characterized in that, The process of using the combined laser beam to process the substrate includes: The combined laser beam is shaped to form a Bessel beam; The substrate to be processed is processed using a Bessel beam.

5. The laser processing method according to claim 1, characterized in that, The combined laser beam is used to modify the area to be processed on the substrate to form a material-modified area. After forming the material modification region, the laser processing method further includes: Through-holes are fabricated in the modified material region using chemical etching; or, The substrate to be processed is divided along the material modification region using a slicing process.

6. The laser processing method according to claim 1, characterized in that, Adjusting the optical path difference between each of the sub-beams so that each sub-beam reaches the same processing position on the substrate at different times includes: By using a retroreflective device disposed on at least one sub-beam optical path, the optical path difference between each sub-beam is adjusted so that the time taken for each sub-beam to reach the same processing position on the substrate to be processed is different.

7. The laser processing method according to claim 6, characterized in that, The retroreflective device includes at least one of a hollow right-angle mirror, a hollow roof mirror, and a hollow retroreflector; And / or, the retroreflective device is connected to the displacement module, and the step of adjusting the optical path difference between each of the sub-beams by means of the retroreflective device disposed in at least one sub-beam optical path, so that the time for each of the sub-beams to reach the same processing position on the substrate to be processed is different, includes: The position of the retroreflective device is adjusted by the displacement module so that the time it takes for each sub-beam to reach the same processing position on the substrate to be processed is different.

8. The laser processing method according to claim 1, characterized in that, Before splitting the incident laser beam into multiple sub-beams, the method further includes: Adjust the beam size of the cross-section of the incident laser beam along the incident direction.

9. The laser processing method according to claim 1, characterized in that, The number of sub-beams is two, including a first sub-beam and a second sub-beam; before splitting the incident laser beam to form multiple sub-beams, the method further includes: The polarization direction of the incident laser beam is modulated; The process of splitting the incident laser beam into multiple sub-beams includes: The incident laser beam, after being modulated by polarization direction, is polarized and split into a first sub-beam and a second sub-beam.

10. A laser modulation method, characterized in that, The method involves using a modulated laser beam to process a transparent solid substrate, comprising: The incident laser beam is split into multiple sub-beams; The optical path difference between each of the sub-beams is adjusted so that the time taken for each sub-beam to reach the same processing position on the transparent solid substrate is different; the optical path difference is used to ensure that the time difference between the arrival of each sub-beam at the same processing position on the substrate is within a time range where the electron and exciton concentrations are higher than a preset concentration threshold; the preset concentration threshold is determined in advance by testing, and the time range within which the electron and exciton concentrations are higher than the preset concentration threshold is determined by testing, and the corresponding optical path difference range is calculated based on the time range and the laser propagation speed; The sub-beams, after optical path difference adjustment, are combined into the same optical path to form a combined laser beam.

11. A laser processing apparatus, characterized in that, The laser processing device includes: Ultrashort pulse lasers are used to emit laser beams; A beam splitting module is deployed in the optical path of the laser beam to split the laser beam into multiple sub-beams; An optical path difference adjustment module, deployed on the output side of the beam splitting module, is used to adjust the optical path difference between each sub-beam so that the time taken for each sub-beam to reach the same processing position on the substrate to be processed is different. The optical path difference is used to ensure that the time difference between the arrival of each sub-beam at the same processing position on the substrate to be processed is within a time range where the electron and exciton concentrations are higher than a preset concentration threshold. The preset concentration threshold is determined in advance through testing, and the time range within which the electron and exciton concentrations are higher than the preset concentration threshold is determined through testing. Based on the time range and the laser propagation speed, the corresponding optical path difference range is calculated. A beam combining module is deployed on the light-emitting side of the optical path difference adjustment module. It is used to combine the sub-beams after optical path difference adjustment into the same optical path to form a combined laser beam. The combined laser beam is used to process the substrate to be processed.

12. A workpiece, characterized in that, The workpiece is processed by the laser processing method as described in any one of claims 1 to 9, or by processing a laser beam controlled by the laser control method as described in claim 10, or by processing with the laser processing apparatus as described in claim 11.

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