Dopant Profiling of Semiconductor Devices by Electron Holography

Tsukasa Hirayama

Abstract: Analyzing the dopant distributions in semiconductors is important because the small amount of impurities (dopants) implanted form electric potential distributions that are responsible for the performance of these devices. However, dopant concentrations are generally as low as 10¹⁵cm^-3～10¹⁹cm^-3 (i.e., less than 0.1 atom％), which is below the contrast level of the images obtained by transmission electron microscopes. It is even difficult to map the dopant distribution for such small concentrations using energy dispersive X-ray spectroscopy (EDS) or electron energy loss spectroscopy (EELS). Electron holography enables electric potential distributions to be observed, and thus is a powerful method for profiling dopant distributions. This paper describes the principle, method and typical applications of electron holography for dopant profiling of semiconductors.

Key words: Electron holography, Dopant profiling, Electric potential distribution, Semiconductor devices