Insulating medium etching device and method based on laser nonlinear frequency multiplication

Abstract

A medium material etching device and method based on laser nonlinear frequency doubling, the device comprising a pneumatic vibration isolation platform, a servo motor, a spindle moving system, a beam shaping system, a fast mirror and a laser. The laser emits ultrafast laser, after the electrically controlled fast mirror, the direction is deflected, after the beam shaping system, converges on the surface of the medium material, finally the irradiated workpiece is immersed in the etching liquid. Due to the irradiation of high density light intensity, the material inside is modified, and the etching rate of different positions in the material inside is significantly different, and after immersion, the surface and inside of the material can form complex micro-nano structure. The medium material etching device disclosed in the application expands the processing range of ultra-precision laser processing, effectively improves the preparation efficiency of complex array structure of medium material, forms the preparation ability of micro-nano structure, and improves the processing precision and processing efficiency, which can be applied to the precision machining of glass material, organic / polymer material and ceramic material and other medium materials.

Description

Technical Field

[0001] This invention belongs to the field of laser and optoelectronic technology, and particularly relates to a dielectric material etching device and method based on laser nonlinear frequency doubling. Background Technology

[0002] With the rapid development of modern micro / nano manufacturing technology, dielectric materials (including glass, ceramics, organic / polymer materials, etc.) are finding increasingly widespread applications in fields such as electronics, optoelectronics, energy, and biomedicine. In the electronics industry, glass substrates, ceramic packaging substrates, and polymer insulating dielectrics have become key basic materials for integrated circuits, display panels, and power electronic devices. In optoelectronics, oxyacid salt nonlinear optical crystals (such as BBO, LBO, KTP, KDP, LiNbO3, etc.) are the core functional dielectrics for laser frequency conversion. In the energy industry, solid electrolytes, insulating and heat-dissipating ceramics, and battery separators play a decisive role in device performance. These dielectric materials often require the fabrication of precise micro / nano structures on their surface or internally to meet specific optical, electrical, thermal, or fluid performance requirements.

[0003] However, existing ultrafast laser processing technologies for dielectric materials still have the following shortcomings: 1. It is difficult to balance processing efficiency and precision. The processing speed of a single ultrafast laser beam is relatively low, making it difficult to meet the efficiency requirements of large-area or batch production. If multi-beam parallel processing is used, the optical path system becomes complex, and it is difficult to guarantee the consistency of the beam spot; 2. Separation of etching and separation processes. In existing technologies, laser-induced modification and subsequent chemical etching to remove the modified area are usually two independent process steps, requiring the transfer of workpieces between different devices, increasing process complexity and positioning errors, and reducing overall processing efficiency; 3. Low laser energy utilization. The energy distribution of an ultrafast laser Gaussian beam without beam shaping is uneven, with excessively high energy density at the center and insufficient energy density at the edges, resulting in blurred boundaries of the modified area and unstable processing quality. At the same time, the short Rayleigh distance of the Gaussian beam limits the depth of focus, which is not conducive to processing dielectric materials with a certain thickness or curved surface.

[0004] Therefore, there is an urgent need for a laser etching device and method that can efficiently and precisely fabricate complex micro-nano structures on dielectric materials to overcome the shortcomings of the existing technologies. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention proposes a dielectric material etching apparatus and method based on laser nonlinear frequency doubling. This apparatus utilizes the nonlinear frequency doubling effect of ultrafast lasers to generate high-density light intensity, inducing localized modification within the dielectric material. Subsequently, the modified regions are selectively removed by immersion in an etching solution, forming complex micro / nano structures. This invention organically combines laser irradiation with subsequent chemical etching, expanding the applicability of ultra-precision laser processing and effectively improving the fabrication efficiency of complex array structures in dielectric materials.

[0006] The technical solution adopted in this invention is as follows: A dielectric material etching apparatus based on laser nonlinear frequency doubling includes a vibration isolation platform, a servo motor, a spindle movement system, a beam shaping system, an electrically controlled fast reflector, and a laser.

[0007] The vibration isolation platform provides stable mechanical support and vibration isolation for the entire etching device, effectively isolating the influence of environmental vibrations (including ground vibration, equipment operation vibration and airflow disturbance) on the processing accuracy and ensuring that the laser focus position remains stable at the nanometer level.

[0008] The servo motor is electrically connected to the spindle motion system, driving the spindle motion system to perform precise positioning and movement in the X, Y, and Z axes. The spindle motion system is mounted on the pneumatic vibration isolation platform, carrying the workpiece (medium material) to be processed and achieving precise positioning and scanning motion at the micrometer to nanometer level in three-dimensional space. Preferably, the spindle motion system adopts a multi-stage motion architecture combining an air-bearing linear guide and a piezoelectric ceramic nano-positioning platform, with a stroke exceeding 500 mm × 500 mm × 50 mm, a displacement resolution better than 1 nm, and a repeatability better than 50 nm.

[0009] The laser is used to emit ultrafast laser pulses. The pulse width of the ultrafast laser is in the femtosecond to picosecond range (preferably 50 fs to 10 ps), the center wavelength is in the near-infrared band (preferably 1030 nm or 1064 nm), the repetition frequency is adjustable from 1 kHz to 10 MHz, and the single pulse energy is adjustable from 1 μJ to 1 mJ. The laser has high beam quality (M 2 With a strength of < 1.3% and excellent power stability (RMS < 1%), it can meet the requirements of high-density light intensity focusing.

[0010] The electrically controlled fast reflector is disposed in the output optical path of the laser and is used to deflect the propagation direction of the laser beam at high speed according to the control signal. The deflection angle range of the electrically controlled fast reflector is ±5°, the deflection response time is <1 ms, and the angle repeatability is <1 μrad. It can realize high-speed scanning of the laser focus on the workpiece surface, and complete the patterning of local areas without the need for overall workpiece movement, significantly improving processing efficiency.

[0011] The beam shaping system is located downstream of the electrically controlled fast reflector and is used to shape the deflected laser beam into a focused spot with a predetermined spatial intensity distribution. The beam shaping system includes a beam expander / collimator, a spatial light modulator (SLM) or a diffractive optical element (DOE), and a focusing objective. Preferably, the beam shaping system can shape a Gaussian beam into a top-hat beam or a Bessel beam to improve energy distribution uniformity and depth of focus. After shaping, the energy non-uniformity of the spot is <5%, which is beneficial for obtaining a clearly defined modified region; the Bessel beam has no diffraction propagation characteristics and a depth of focus on the millimeter scale, making it suitable for three-dimensional internal processing of thick dielectric materials.

[0012] The focusing objective focuses the shaped laser beam onto the surface or a predetermined depth within the dielectric material. The focusing objective is an achromatic objective with a numerical aperture (NA) of 0.1 to 0.9 or a long working distance objective, and air objectives, oil immersion objectives, or water immersion objectives can be selected according to processing requirements.

[0013] Furthermore, the etching apparatus also includes an etching solution supply system and a workpiece clamping fixture.

[0014] The etching solution supply system provides a chemical etching solution to the laser-irradiated workpiece, causing selective dissolution or stripping of the laser-modified area. The choice of etching solution depends on the chemical composition of the dielectric material. For silicate glass materials, hydrofluoric acid (HF) solution or buffered oxide etching solution (BOE) can be used; for oxide ceramic materials (such as Al2O3, ZrO2), phosphoric acid or a mixture of hydrofluoric acid can be used; for nitride ceramics (such as Si3N4, AlN), hot phosphoric acid or ammonium fluoride solution can be used; for oxyacid acid nonlinear optical crystals (such as BBO, LBO, KTP, KDP, LiNbO3), dilute acid solution or selective ion exchange etching solution can be used; for organic / polymer materials, appropriate organic solvents or alkaline etching solutions can be used. The concentration, temperature, and immersion time of the etching solution can be adjusted according to the degree of modification and the desired structural morphology.

[0015] The workpiece clamping fixture is mounted on the spindle moving system and is used to fix and position the workpiece of the medium material to be processed.

[0016] The fixture has multi-degree-of-freedom adjustment capabilities, allowing for fine-tuning of the pitch and yaw angles to ensure that the workpiece machining surface is perpendicular to the laser beam or at a predetermined angle. Preferably, the fixture employs vacuum adsorption or mechanical clamping and integrates a temperature control module, which can maintain a constant workpiece temperature during processing, reducing positioning errors caused by thermal expansion and contraction.

[0017] A method for etching dielectric materials based on laser nonlinear frequency doubling includes the following steps: Step S1: Fix the workpiece of the medium material to be processed on the workpiece clamping fixture, and adjust the position of the workpiece by means of the spindle moving system so that the laser focus is aligned with the predetermined processing start position of the workpiece.

[0018] Step S2: Activate the laser to emit an ultrafast laser pulse. The ultrafast laser is deflected by the electrically controlled fast reflector, then shaped by the beam shaping system, and finally focused by the focusing objective at a predetermined depth on the workpiece surface or inside. The peak power density of the laser is higher than the nonlinear absorption threshold of the dielectric material, causing multiphoton absorption and / or tunneling ionization in the focal region, resulting in localized material modification. The modification includes changes in material density, breaking or recombination of chemical bonds, and micro / nano-scale phase transitions (such as densification or nanocrystal precipitation in glass structures), resulting in different chemical etching rates in the modified region compared to the unmodified region.

[0019] Step S3: Simultaneously or after laser irradiation, the laser focus is scanned on the workpiece along a predetermined trajectory by the high-speed deflection of the electrically controlled fast reflector and / or the precise movement of the spindle moving system, forming the desired modified pattern. The scanning methods include: single-point successive scanning, line scanning, surface scanning, and three-dimensional volume scanning. For the fabrication of complex micro / nano array structures, the electrically controlled fast reflector can achieve kHz-level fast grating scanning. Combined with the stepping motion of the spindle moving system, periodic or non-periodic micro / nano structure arrays can be efficiently fabricated over a large area.

[0020] Step S4: The laser-irradiated workpiece is transferred to an etching solution and immersed for a predetermined time. The etching solution reacts chemically with the laser-modified area, causing the modified material to dissolve or peel off at a higher rate than the unmodified area, thereby forming a micro / nano structure corresponding to the laser-modified pattern on or inside the workpiece surface. The immersion time is adjusted from several seconds to several hours depending on the modification depth, etching solution concentration, and temperature. Preferably, the etching process can be performed under ultrasonic assistance or heating conditions to accelerate the etching rate and improve etching uniformity.

[0021] Step S5: Remove the workpiece from the etching solution, rinse it with deionized water and dry it to obtain a dielectric material processing part with a complex micro-nano structure.

[0022] This invention provides a device and method for etching dielectric materials based on laser nonlinear frequency doubling. It induces localized modification within the dielectric material using an ultrafast laser, followed by selective removal of the modified regions using chemical etching, achieving high-precision and high-efficiency fabrication of complex micro / nano structures. This invention has the following significant advantages: (1) Non-contact processing, no thermal damage, no subsurface damage, suitable for brittle and heat-sensitive media materials; (2) Laser irradiation and chemical etching are integrated on the same platform, reducing positioning errors and improving processing efficiency; (3) The electronically controlled fast reflector enables high-speed scanning, which, together with the spindle moving system, enables the efficient fabrication of large-area array structures; (4) The beam shaping system improves the uniformity of energy distribution and depth of focus, thereby enhancing processing quality and dimensional expansion capabilities; (5) It has wide material adaptability and can process a variety of media materials such as glass, ceramics, nonlinear optical crystals, fluoride crystals and polymers.

[0023] In summary, this invention has broad application prospects in fields such as micro-nano manufacturing, optoelectronic devices, and flexible electronics. Attached Figure Description

[0024] Figure 1 is a schematic diagram of the overall structure of the dielectric material etching device based on laser nonlinear frequency doubling proposed in this invention; Figure 1. Reference numerals: 101. Vibration Isolation Platform: Adopting an active pneumatic vibration isolation system, it can provide a sub-nanometer level vibration isolation environment for the entire processing system; 102. Spindle moving system: Installed on the vibration isolation platform 101, it adopts a two-stage motion architecture: the first stage is a coarse positioning platform driven by an air-bearing linear motor; the second stage is a fine positioning platform driven by piezoelectric ceramics, which can support precise displacement control in three-dimensional space.

[0025] 103. Servo motor: Provides driving force for the movement of the spindle motion system 102; 104. Laser: Outputs femtosecond / nanosecond laser beams; 105. Electrically controlled fast reflector: a biaxial fast reflector driven by piezoelectric ceramics, which can realize rapid scanning of the laser focus in the XY plane; 106. Beam Shaping System: This system includes a beam expander and collimator lens group and a spatial light modulator. It collimates the laser beam while expanding or shrinking it. It also supports real-time modulation of the beam's phase and amplitude to shape flat-top beams or Bessel beams. 107. Focusing objective lens: located downstream of the electrically controlled fast reflector 106, it focuses the laser beam onto the processing plane. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. Obviously, the described embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0028] Example 1: Device Structure Figure 1 shows a schematic diagram of the overall structure of a dielectric material etching apparatus based on laser nonlinear frequency doubling in one embodiment of the present invention. The etching apparatus includes: a vibration isolation platform 101, a spindle moving system 102, a servo motor 103, a laser 104, an electrically controlled fast reflector 105, a beam shaping system 106, a focusing objective lens 107, a workpiece clamping fixture (not shown), an etching solution supply system (not shown), and a control system (not shown).

[0029] The pneumatic vibration isolation platform 101 adopts an active pneumatic vibration isolation system with a vibration isolation frequency of <1 Hz, a vibration isolation efficiency of >90%@10 Hz, and a platform surface flatness of <5 μm / 500 mm, which can provide a sub-nanometer level vibration isolation environment for the entire processing system.

[0030] The spindle movement system 102 is mounted on the pneumatic vibration isolation platform 101 and adopts a three-stage motion architecture: the first stage is a coarse positioning platform driven by an air-bearing linear motor (stroke 200 mm × 200 mm × 50 mm, positioning accuracy ±1 μm, maximum speed 500 mm / s); the second stage is a fine positioning platform driven by a piezoelectric ceramic (stroke 200 μm × 200 μm × 50 μm, resolution 0.1 nm, repeatability ±2 nm); and the third stage is a fast-response platform driven by a voice coil motor (stroke ±20 μm, bandwidth >1 kHz), used to compensate for high-frequency vibrations and achieve rapid scanning within a small range.

[0031] The laser 105 is a ytterbium-doped fiber femtosecond laser with a center wavelength of 1030 nm, a pulse width of 300 fs, a repetition rate of 200 kHz, a maximum single-pulse energy of 200 μJ, a maximum average power of 40 W, and a beam quality of M.2 <1.2. The output beam of the laser 105 enters the electrically controlled fast reflector 106 after passing through the collimator.

[0032] The electrically controlled fast reflector 106 described above is a piezoelectric ceramic driven biaxial fast reflector with a maximum deflection angle of ±5°, an angular resolution of <0.5 μrad, and a response bandwidth of >2 kHz. The fast reflector can achieve rapid scanning of the laser focus in the XY plane, with a scanning range of approximately 10 mm × 10 mm (under a focal length of 100 mm).

[0033] The beam shaping system 107 is located downstream of the electrically controlled fast reflector 106 and includes a beam expander collimator group 107a, a spatial light modulator (SLM) 107b, and a focusing objective 108. The beam expander collimator group 107a expands the laser beam from its original diameter of 3 mm to 10 mm; the SLM 107b is a liquid crystal spatial light modulator with 1920×1080 pixels and a pixel pitch of 8 μm, which can modulate the phase and amplitude of the beam in real time to achieve flat-top beam or Bessel beam shaping; the focusing objective 108 is a long working distance achromatic objective (NA=0.5, working distance 10 mm), which can focus the shaped beam to a diffraction-limited spot (approximately 1.2 μm).

[0034] The etching solution supply system 109 includes an etching solution storage tank, a peristaltic pump, a temperature control unit, and a waste liquid recovery unit. The etching solution is delivered to the workpiece surface or immersion tank at a controllable flow rate by the peristaltic pump. The temperature control unit can maintain the etching solution temperature within the range of 20~80°C. The waste liquid recovery unit collects and neutralizes the used etching solution.

[0035] The control system (not shown) is a motion control and laser synchronization system based on an industrial PC, integrating a motion controller, a laser triggering module, a vision positioning module, and a data acquisition module. The control system coordinates the timing actions of the servo motor 103, the electrically controlled fast reflector 106, the laser 105, and the etching solution supply system 109 to achieve automated processing.

[0036] Example 2: Fabrication of a glass through-hole array In this embodiment, quartz glass (SiO2, 1 mm thick) is used as the processing object, and an array of through holes with a cycle of 100 μm and a depth of 1 mm is prepared using the etching device and method of the present invention.

[0037] Step S1: Fix the quartz glass workpiece on the workpiece clamping fixture 104, and adjust the workpiece position through the spindle moving system 102 so that the laser focus is located 10 μm below the upper surface of the workpiece.

[0038] Step S2: The laser 105 is activated, with a pulse width of 300 fs, a repetition frequency of 200 kHz, and a single pulse energy of 30 μJ. After being deflected by the electrically controlled fast reflector 106 and shaped by the beam shaping system 107, the laser beam is focused onto the workpiece by the focusing objective lens 108. The SLM 107b is loaded with a flat-top beam phase mask, causing the beam spot at the focal point to have a flat-top distribution with a diameter of approximately 3 μm. The peak power density of the laser is approximately 2 × 10⁻⁶. 13 W / cm 2 It is higher than the multiphoton absorption threshold of quartz glass (approximately 10). 12 W / cm 2 This causes densification modification in the focal region.

[0039] Step S3: The electrically controlled fast reflector 106 performs a grating scan in the XY plane at a frequency of 2 kHz, with a scanning interval of 3 μm and a scanning area of ​​5 mm × 5 mm. After each through-hole contour is scanned, the spindle movement system 102 steps 100 μm to the next lens position, repeating the above scanning process until the entire 50×50 array is scanned. The control system synchronizes laser triggering and scanning motion in real time to ensure the processing consistency of each lens contour.

[0040] Step S4: Transfer the laser-irradiated quartz glass workpiece to an etching solution immersion tank. The etching solution is a buffered oxide etching solution (BOE, HF:NH4F:H2O=1:6:10), at a temperature of 40°C, for an immersion time of 30 min. Because the etching rate of the laser-modified region (approximately 200 nm / min) is significantly higher than that of the unmodified region (approximately 20 nm / min), the etching selectivity ratio reaches 10:1. The modified region is selectively removed, forming a pit, i.e., a through-hole structure, at the center of each scan contour.

[0041] Step S5: Remove the workpiece from the etching solution, rinse it with deionized water for 5 minutes, and dry it with nitrogen.

Claims

1. A dielectric material etching apparatus based on laser nonlinear frequency doubling, characterized in that, include: Vibration isolation platform; The spindle movement system is installed on the vibration isolation platform; A servo motor, electrically connected to the spindle moving system, is used to drive the spindle moving system to move in three-dimensional space; Lasers are used to emit ultrafast laser pulses; An electrically controlled fast reflector is disposed in the output optical path of the laser to deflect the laser beam at high speed. A beam shaping system is disposed in the downstream optical path of the electronically controlled fast reflector and is used to shape the laser beam into a focused spot with a predetermined spatial intensity distribution. A focusing objective lens is used to focus a shaped laser beam onto the surface or interior of a dielectric material.

2. The etching apparatus according to claim 1, characterized in that, The ultrafast laser has a pulse width of 50 fs to 10 ps, ​​a center wavelength of 700 nm to 1100 nm, and a repetition frequency of 1 kHz to 10 MHz.

3. The etching apparatus according to claim 1, characterized in that, The beam shaping system includes a beam expander and collimator, a spatial light modulator, and a focusing objective. The spatial light modulator is used to shape a Gaussian beam into a flat-top beam or a Bessel beam.

4. The etching apparatus according to claim 1, characterized in that, It also includes an etching solution supply system for supplying chemical etching solution to workpieces that have been irradiated by laser.

5. The etching apparatus according to claim 1, characterized in that, The spindle movement system adopts a multi-level motion architecture that combines linear guides with a piezoelectric ceramic nanopositioning platform.

6. A method for etching dielectric materials based on laser nonlinear frequency doubling, characterized in that, Includes the following steps: Step S1: Fix the workpiece of the medium material to be processed, and adjust its position so that the laser focus is aligned with the predetermined processing start position; Step S2: An ultrafast laser pulse is emitted, deflected by an electrically controlled fast reflector and shaped by a beam shaping system, and then focused by a focusing objective on the surface or interior of the workpiece, causing nonlinear absorption and localized modification in the focal region. Step S3: The laser focus is scanned along a predetermined trajectory by an electrically controlled fast reflector and / or a spindle moving system to form a modified pattern; Step S4: Immerse the laser-irradiated workpiece in an etching solution to selectively remove the laser-modified areas and form micro / nano structures; Step S5: Remove the workpiece, rinse and dry it to obtain the machined part.

7. The etching method according to claim 6, characterized in that, The dielectric material is selected from glass materials, oxide ceramics, nitride ceramics, oxyacid nonlinear optical crystals, fluoride crystals, or organic / polymer materials.

8. The etching method according to claim 6, characterized in that, The etching solution is selected according to the chemical composition of the medium material. For silicate glass, hydrofluoric acid or buffered oxide etching solution is used; for oxide ceramics, a mixture of phosphoric acid or hydrofluoric acid is used; for oxyacid crystals, a dilute acid solution is used; and for polymer materials, an organic solvent or alkaline etching solution is used.

9. The etching method according to claim 6, characterized in that, The peak power density of the laser modification is 10. 12 Up to 10 14 W / cm 2 The temperature of the etching solution is 20°C to 100°C, and the immersion time is 10 seconds to 24 hours.

10. The etching method according to claim 6, characterized in that, The beam shaping system shapes the laser into a flat-top beam with a spot energy non-uniformity of <5%; or into a Bessel beam with a focal depth of 0.1 mm to 5 mm.

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