基于多层膜光栅的AFM探针结构表征研究

原子力显微镜是微纳米测量领域主要测量工具之一。由于原子力显微镜探针不可能无限尖锐,使得测量图像包含了一部分探针信息,这是其图像失真的一大影响因素。通过获取探针形状和尺寸,可以有效去除测量图像的"探针效应"从而提升准确度。文中以研制良好样品内一致性的探针校准器为目标,应用Si/SiO2多层膜光栅技术,初步研制了20 nm标称值的线宽结构用于原子力显微镜探针校准。表征结果显示,RFESP型(Rectangular Front Etched Silicon Probe)探针稳定扫描时探针前角由15°增加至36°左右,探针后角由25°增加至45°左右,呈现钝化趋势。由此表明,基于Si/SiO2多层膜光栅技术研制的线宽型探针表征器可以快速表征出探针侧壁角度信息,是原子力显微镜探针扫描过程中探针形貌快速监测和估计的有效手段,对于促进探针表征与图像准确度提升均具有重要意义。

Investigation of AFM tip characterization based on multilayer gratings

Atomic force microscope(AFM) is one of the main instruments in the microscale and nanoscale measurement area. Since the AFM tip can't be infinitely sharp, the shape of the tip is included in AFM image. This is a big source of image distortion. To obtain the shape and dimensions of tip is an effective method to remove the "tip effect" and improve the accuracy of measurement images. In this study, tip characterizers with high intra-sample uniformity were fabricated by utilizing the Si/SiO₂ multilayer gratings technology, and critical dimension(CD) structures with a nominal CD of 20 nm had been fabricated to calibrate the tip. The calibration results showed that the selected AFM tip(Rectangular Front Etched Silicon Probe, RFESP) became blunt after scanning, together with the front side angle(15°) and back side angle (25°) increased to 36° and 45°, respectively. Therefore, the tip characterizers formed by the Si/SiO₂ multilayer CD structures can be used to quickly obtain the side angle information, which is an effective method to complete the fast check and estimations of tip shapes during the AFM scanning. The investigation of AFM tip characterization based on multilayer gratings are meaningful for the promotion of accuracy in AFM measurement images.