Slicing and post-treatment of SiC crystals have been a significant challenge in the integrated circuit and microelectronics industry.To compete with wire-sawing and mechanical grinding technology,a promis-ing approach...Slicing and post-treatment of SiC crystals have been a significant challenge in the integrated circuit and microelectronics industry.To compete with wire-sawing and mechanical grinding technology,a promis-ing approach combining laser slicing and laser polishing technologies has been innovatively applied to increase utilization and decrease damage defects for single crystal 4H-SiC.Significant material utiliza-tion has been achieved in the hybrid laser processes,where material loss is reduced by 75%compared to that of conventional machining technologies.Without any special process control or additional treat-ment,an internally modified layer formed by laser slicing can easily separate the 4H-SiC crystals using an external force of about∼3.6 MPa.The modified layer has been characterized using a micro-Raman method to determine residual stress.The sliced surface exhibits a combination of smooth and coarse appearances around the fluvial morphology,with an average surface roughness of over S_(a) 0.89μm.An amorphous phase surrounds the SiC substrate,with two dimensions of lattice spacing,d=0.261 nm and d=0.265 nm,confirmed by high-resolution transmission electron microscopy(HRTEM).The creation of laser-induced periodic surface nanostructures in the laser-polished surface results in a flatter surface with an average roughness of less than S_(a) 0.22μm.Due to the extreme cooling rates and multiple thermal cy-cles,dissociation of Si-C bonding,and phase separation are identified on the laser-polished surface,which is much better than that of the machining surface.We anticipate that this approach will be applicable to other high-value crystals and will have promising viability in the aerospace and semiconductor industries.展开更多
N6-methyladenosine(m6 A)is the most prevalent internal chemical modification found in eukaryotic mRNAs,playing a critical regulatory role across various stages of mRNA metabolism[1].With the development of RNA immunop...N6-methyladenosine(m6 A)is the most prevalent internal chemical modification found in eukaryotic mRNAs,playing a critical regulatory role across various stages of mRNA metabolism[1].With the development of RNA immunoprecipitation using m6 A-specific antibodies followed by sequencing(m6 ARIP-seq),m6 A modification has been widely reported in viral RNAs across a diverse range of viruses that replicate either in the nucleus or the cytoplasm[2].展开更多
基金supported by National Natural Science Foundation of China(No.62304249)a project funded by China Postdoctoral Science Foundation(No.2023M733704).
文摘Slicing and post-treatment of SiC crystals have been a significant challenge in the integrated circuit and microelectronics industry.To compete with wire-sawing and mechanical grinding technology,a promis-ing approach combining laser slicing and laser polishing technologies has been innovatively applied to increase utilization and decrease damage defects for single crystal 4H-SiC.Significant material utiliza-tion has been achieved in the hybrid laser processes,where material loss is reduced by 75%compared to that of conventional machining technologies.Without any special process control or additional treat-ment,an internally modified layer formed by laser slicing can easily separate the 4H-SiC crystals using an external force of about∼3.6 MPa.The modified layer has been characterized using a micro-Raman method to determine residual stress.The sliced surface exhibits a combination of smooth and coarse appearances around the fluvial morphology,with an average surface roughness of over S_(a) 0.89μm.An amorphous phase surrounds the SiC substrate,with two dimensions of lattice spacing,d=0.261 nm and d=0.265 nm,confirmed by high-resolution transmission electron microscopy(HRTEM).The creation of laser-induced periodic surface nanostructures in the laser-polished surface results in a flatter surface with an average roughness of less than S_(a) 0.22μm.Due to the extreme cooling rates and multiple thermal cy-cles,dissociation of Si-C bonding,and phase separation are identified on the laser-polished surface,which is much better than that of the machining surface.We anticipate that this approach will be applicable to other high-value crystals and will have promising viability in the aerospace and semiconductor industries.
基金supported by the National Key Research and Development Program of China(2022YFD1400804)the Innovation and Development Program of Beijing Academy of Agriculture and Forestry Science(BAAFS)(KJCX20240328)BAAFS Startup Foundation for Advanced Talents(030210094).
文摘N6-methyladenosine(m6 A)is the most prevalent internal chemical modification found in eukaryotic mRNAs,playing a critical regulatory role across various stages of mRNA metabolism[1].With the development of RNA immunoprecipitation using m6 A-specific antibodies followed by sequencing(m6 ARIP-seq),m6 A modification has been widely reported in viral RNAs across a diverse range of viruses that replicate either in the nucleus or the cytoplasm[2].
