扫描探针显微镜在激光纳米加工技术上的应用和进展

综述了扫描探针显微镜在激光纳米加工技术上应用的最新进展,介绍了纳米结构的形成机理。     

Direct Nanomachining on Semiconductor Wafer By Scanning Electrochemical Microscopy

Scanning electrochemical microscopy (SECM) is one of the most important instrumental methods of modern electrochemistry due to its high spatial and temporal resolution. We introduced SECM into nanomachining by feeding the electrochemical modulations of the tip electrode back to the positioning system, and we demonstrated that SECM is a versatile nanomachining technique on semiconductor wafers using electrochemically induced chemical etching. The removal profile was correlated to the applied tip current when the tip was held stationary and when it was moving slowly (<20 μm s⁻¹), and it followed Faraday's law. Both regular and irregular nanopatterns were translated into a spatially distributed current by the homemade digitally controlled SECM instrument. The desired nanopatterns were “sculpted” directly on a semiconductor wafer by SECM direct-writing mode. The machining accuracy was controlled to the sub-micrometer and even nanometer scales. This advance is expected to play an important role in electrochemical nanomachining for 3D micro/nanostructures in the semiconductor industry.     

单晶硅微纳构件加工表面性能的时变性研究

采用蒙特卡罗方法和分子动力学方法相结合, 模拟单晶硅微纳构件加工表面的时效过程, 研究其对加工表面质量和构件力学性能的影响. 模拟结果表明: 在时效过程中, 单晶硅微纳构件加工变质层的有序度显著提高, 残余应力大幅降低, 表面粗糙度略有增加, 此外还发现加工变质层中非晶硅原子在时效过程中大幅减少, 部分非晶硅出现了再结晶现象, 其中部分BCT5-Si以及金属相(Si-Ⅱ)结构原子转化为金刚石结构(Si-I). 时效作用对加工后单晶硅微纳构件表面性能具有重要的影响, 同时可以提高微纳构件的拉伸力学性能. 关键词： 蒙特卡罗方法 纳米加工 表面性能 时变性     

Electrochemical nanomachining

Free of tool wear, residual stress, and surface damage, electrochemical nanomachining (ECNM) plays an irreplaceable role in advanced manufacturing, via the production of ultra-large scale integrated circuits, microelectromechanical systems, and various nanodevices. The principles of ECNM are classified as electroforming, electrolysis, electrochemical corrosion, and etching. The working modes of ECNM include direct writing and template forming. ECNM applies to not only the fabrication of three-dimensional nanostructures but also the production of super-smooth surfaces with roughness no higher than 1 nm. Both of these are crucial in modern advanced manufacturing. The key point of ECNM is the spatial confinement of electrochemical reactions. This review will focus on this point and briefly introduce the principles, methodologies, applications, and prospects of ECNM.     

Interfacial-Strain-Controlled Ferroelectricity in Self-Assembled BiFeO3 Nanostructures

Self-assembled BiFeO₃-CoFe₂O₄ (BFO-CFO) vertically aligned nanocomposites are promising for logic, memory, and multiferroic applications, primarily due to the tunability enabled by strain engineering at the prodigious epitaxial vertical interfaces. However, local investigations directly revealing functional properties in the vicinity of such critical interfaces are often hampered by the size, geometry, microstructure, and concomitant experimental artifacts. Ferroelectric switching in the presence of lateral distributions of vertical strain thus remains relatively unexplored, with broader implications for all strain-engineered functional devices. By implementing tomographic atomic force microscopy, 3D domain orientation mapping, and spatially-resolved ferroelectric switching movies, local tensile strain significantly impacts the ferroelectric switching, principally by retarding domain nucleation in the BFO nearest to the vertically epitaxial tensile-strained interfaces. The relaxed centers of the BFO pillars become preferred domain nucleation and growth sites for low biases, with up to an order of magnitude change in the edge:center switching ratio for high biases. The new, multi-dimensional imaging approach—and its corresponding insights especially for directly strained interface effects on local properties—thereby advances the fundamental understanding of polarization switching and provides design principles for optimizing functional response in confined nanoferroic systems.