用于单电子自旋探测微悬臂梁的制作及端头磁针尖设计

Fabrication of Ultra-Sensitive Cantilever for Single Electron Spin Detection and Design of Magnetic Tip

提出一种用于单电子自旋探测微悬臂梁的制作方法。采用顶层Si厚度为1μm的SOI硅片,在器件层刻蚀出悬臂梁图形后,利用热氧化将Si梁减薄至0.5μm,同时生成SiO2保护层。在KOH溶液进行体硅刻蚀过程中,以黑蜡和SiO2保护层作为正面保护,之后用溶液置换方法完成埋氧层去除及悬臂梁清洗过程。悬臂梁尺寸为465μm×10μm×0.5μm,室温真空中Q值为23000,在低温环境中可以满足单电子自旋探测要求。分析比较了球体、圆锥体、圆柱体三种磁针尖磁场梯度分布,为磁针尖结构设计提供了依据。

We have designed and fabricated the ultra-sensitive cantilevers for single electron spin detection.A SOI wafer with a 1 μm-thick device layer was used as the fabrication material.The cantilevers were patterned on the device layer,and then thinned to 0.5 μm-thick through thermal oxidation;meanwhile,an oxide protection layer for cantilever was generated.During the bulk silicon etching,the cantilever was protected by black wax and the silicon oxide.The buried oxide layer etching and the cantilever cleaning were both under liquid without pulling it out.The Q factor of a cantilever with 465 μm×10 μm×0.5 μm dimensions is 23 000 in a vacuum chamber at room temperature.It is believed that the cantilever is sensitive enough for single spin detection at low temperature.We simulated the magnetic field of three types of magnet tips,and found that a conical magnet tip shows the strongest field gradient at the near field.