Layer or Strip Resistance Measurement by Electron Beam Induced Current Technique in a Scanning Electron Microscope

摘要

An application of scanning electron microscopy (SEM) electron beam induced current (EBIC) technique for measurement of layer or strip resistance and sheet (surface) resistance is described. In the method a high electron beam current is used. In this range the EBIC (I_(EBIC)) depends on the overall resistance of EBIC circuit. It includes a specimen resistance as well, as generated carriers create I_(EBIC) current that flows along the measured layer or strip to an ohmic contact. A shift of the electron beam towards the ohmic contact on the layer (or on the strip) changes resistance of layer (or strip) between the e-beam placement and the contact. The change of resistance that results is compensated using a changeable resistance (e.g. a decade resistance box). Provided constant I_(EBIC) despite the e-beam movement brings values of the resistance and the sheet resistance for the investigated layer or strip. Spatial distributions of resistance and local inhomogeneities can be also revealed. The method was used for the characterization of lateral confinements in semiconductor laser heterostructures manufactured by Molecular Beam Epitaxy and wet chemical or reactive ion etching. The method can be used for very thin layers and is expected to be applicable for small-size objects as nanostructures.