Dedicated near-field microscopies for electronic materials and devices

Abstract

With the ongoing reduction of structures sizes within electronic devices inspection tools have to be used allowing a resolution of below 50nm. This is not only necessary for a mere topological evaluation of materials or devices under test, but even more important for the nanoscopic determination of material parameters and device properties. When using waves as probes for this purpose, near-field techniques are quite often the only means for overcoming limitations in spatial resolution as due to Rayleigh's criterion, independently of the nature of the wave type used. In this manner acoustic and thermal waves can be applied for very high resolution testing as well as the well known scanning near-field optical microscope. Moreover, such techniques are not limited to simple systems in which the probing wave and the resulting interaction product are of same nature, but more complicated systems may be suitable to gain the information needed. In this manner near-field optical microscopy can be used for optical induced current measurements as well as for nanoscopic cathodoluminescence experiments. To achieve a comprehensive information on the sample, results gained with one special technique can be compared with others, such as scanning thermal or acoustic microscopy. These allow determination of mechanical and thermal properties with appropriate spatial resolution to be compared with, for instance, optoelectronic structures. The necessary instrumentation is described for such experiments with emphasis on the scanning near-field optical microscope. Examples for the application of near-field microscopies will be given for silicon technology, compound semiconductors, and ferroelectric ceramics.