Microgrooves with diverse cross-sections are required in various fields but remain a significant challenge in precision machining,especially for hard-to-machine materials.Patterned laser ablation offers an avenue for ...Microgrooves with diverse cross-sections are required in various fields but remain a significant challenge in precision machining,especially for hard-to-machine materials.Patterned laser ablation offers an avenue for fabricating microgrooves on any material with notably enhanced shape diversity.However,it is hard to precisely control the grooves'cross-sectional profiles due to the complex ablation process,including the diffraction-induced energy distribution variations away from the focal plane and the inconsistent polarization-related energy absorption.These factors complicate the relationship between beam spot shape and ablated groove shape,making it challenging to design appropriate spot shapes for specific groove requirements.Here,we propose an adaptive beam-shaping method for laser spot design to improve microgrooves'shape accuracy.Combining laser diffraction and polarization effects,a profile evolution model of the laser ablation is established to accurately predict groove shapes,guiding the iterative beam-shaping procedure.The beam spot shape is iteratively fine-tuned until the deviation between the simulated and the target grooves'profile meets the accuracy requirements.The grooves'profile deviations are significantly reduced,with the final profile's root mean square error decreased to less than 0.5μm when processing microgrooves with a width of 10μm.Various microgrooves with precise cross-sections,including triangles,trapezoids,and functionally contoured micro structures,are achieved by patterned laser direct writing assisted with the adaptive beam-shaping method.This method paves the way for laser ablation of microgrooves with high shape accuracy for traditional hard-to-machine materials.展开更多
We describe how a direct combination of an axicon and a lens can represent a simple and efficient beam-shaping solution for laser material processing applications.We produce high-angle pseudo-Bessel micro-beams at 155...We describe how a direct combination of an axicon and a lens can represent a simple and efficient beam-shaping solution for laser material processing applications.We produce high-angle pseudo-Bessel micro-beams at 1550 nm,which would be difficult to produce by other methods.Combined with appropriate stretching of femtosecond pulses,we access optimized conditions inside semiconductors allowing us to develop high-aspect-ratio refractive-index writing methods.Using ultrafast microscopy techniques,we characterize the delivered local intensities and the triggered ionization dynamics inside silicon with 200-fs and 50-ps pulses.While similar plasma densities are produced in both cases,we show that repeated picosecond irradiation induces permanent modifications spontaneously growing shot-after-shot in the direction of the laser beam from front-surface damage to the back side of irradiated silicon wafers.The conditions for direct microexplosion and microchannel drilling similar to those today demonstrated for dielectrics still remain inaccessible.Nonetheless,this work evidences higher energy densities than those previously achieved in semiconductors and a novel percussion writing modality to create structures in silicon with aspect ratios exceeding~700 without any motion of the beam.The estimated transient change of conductivity and measured ionization fronts at near luminal speed along the observed microplasma channels support the vision of vertical electrical connections optically controllable at GHz repetition rates.The permanent silicon modifications obtained by percussion writing are light-guiding structures according to a measured positive refractive index change exceeding 10-2.These findings open the door to unique monolithic solutions for electrical and optical through-silicon-vias which are key elements for vertical interconnections in 3D chip stacks.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.52375438)the Guangdong Talent Project(Grant No.2023TQ07Z453)+1 种基金the Shenzhen Science and Technology Programs(Grant Nos.JCYJ20220818100408019 and JSGG20220831101401003)Jiangyin-SUSTech Innovation Fund。
文摘Microgrooves with diverse cross-sections are required in various fields but remain a significant challenge in precision machining,especially for hard-to-machine materials.Patterned laser ablation offers an avenue for fabricating microgrooves on any material with notably enhanced shape diversity.However,it is hard to precisely control the grooves'cross-sectional profiles due to the complex ablation process,including the diffraction-induced energy distribution variations away from the focal plane and the inconsistent polarization-related energy absorption.These factors complicate the relationship between beam spot shape and ablated groove shape,making it challenging to design appropriate spot shapes for specific groove requirements.Here,we propose an adaptive beam-shaping method for laser spot design to improve microgrooves'shape accuracy.Combining laser diffraction and polarization effects,a profile evolution model of the laser ablation is established to accurately predict groove shapes,guiding the iterative beam-shaping procedure.The beam spot shape is iteratively fine-tuned until the deviation between the simulated and the target grooves'profile meets the accuracy requirements.The grooves'profile deviations are significantly reduced,with the final profile's root mean square error decreased to less than 0.5μm when processing microgrooves with a width of 10μm.Various microgrooves with precise cross-sections,including triangles,trapezoids,and functionally contoured micro structures,are achieved by patterned laser direct writing assisted with the adaptive beam-shaping method.This method paves the way for laser ablation of microgrooves with high shape accuracy for traditional hard-to-machine materials.
基金conducted using LaMP facilities at LP3.The project received funding from the French National Research Agency(ANR-22-CE92-0057-0,KiSS project)and the European Union’s Horizon 2020 research and innovation program under grant agreements No.101034324(MSCA-COFUND)and No.724480(ERC).
文摘We describe how a direct combination of an axicon and a lens can represent a simple and efficient beam-shaping solution for laser material processing applications.We produce high-angle pseudo-Bessel micro-beams at 1550 nm,which would be difficult to produce by other methods.Combined with appropriate stretching of femtosecond pulses,we access optimized conditions inside semiconductors allowing us to develop high-aspect-ratio refractive-index writing methods.Using ultrafast microscopy techniques,we characterize the delivered local intensities and the triggered ionization dynamics inside silicon with 200-fs and 50-ps pulses.While similar plasma densities are produced in both cases,we show that repeated picosecond irradiation induces permanent modifications spontaneously growing shot-after-shot in the direction of the laser beam from front-surface damage to the back side of irradiated silicon wafers.The conditions for direct microexplosion and microchannel drilling similar to those today demonstrated for dielectrics still remain inaccessible.Nonetheless,this work evidences higher energy densities than those previously achieved in semiconductors and a novel percussion writing modality to create structures in silicon with aspect ratios exceeding~700 without any motion of the beam.The estimated transient change of conductivity and measured ionization fronts at near luminal speed along the observed microplasma channels support the vision of vertical electrical connections optically controllable at GHz repetition rates.The permanent silicon modifications obtained by percussion writing are light-guiding structures according to a measured positive refractive index change exceeding 10-2.These findings open the door to unique monolithic solutions for electrical and optical through-silicon-vias which are key elements for vertical interconnections in 3D chip stacks.
