半导体表面电学特性微观四点探针测试技术研究进展

Latest development of electrical characterization of semicondutor surface by microscopic four-point probe technique

四探针法是材料学及半导体行业电学表征的常用方法。随着微电子器件尺度持续减小,新型纳米材料研究不断深入,须将探针间距控制到亚微米及其以下范畴才能获得更高的空间分辨率和表面灵敏度。近年来研究人员借助显微技术开发出两类微观四点探针测试系统,即整体式微观四点探针和独立四点扫描隧道显微镜探针系统,随着现代微加工技术的发展,当前探针间距已缩小到几十纳米范围。本文综述了微观四点探针技术近年来的研究进展,主要包括测试理论、系统结构与探针制备。其中,特别详述了涉及探针制备的方法、技术及所面临问题,并展望了微观四点探针研究的发展方向,并给出了一些具体建议。

Four-point probe characterization is a usual method for studying the electrical properties of solids and thin films.The distance between tip and sample in four-point probe technique has to be reduced to sub-micro scale at least in order to obtain expected surface sensitivity and spatial resolution.Therefore,microscopic four-point probes（M4PPs） need to be combined with some microscopy techniques.Two types of M4PPs have been developed in the past few years,which are monolithic micro-four-point probes and four-point scanning tunneling microscopy probes.In this paper,we review the latest development of M4PPs from aspects of system construction,probe structure and test theories.The approaches of probe preparation are discussed in detail.Probe life and sample surface damage are another two big challenges for the microscopic four-point probe technique.To deal with such problems,flexible cantilevers can be used as the probe by keeping a certain angle to the sample surface.