Defect delineation and characterization in SiGe, Ge and other semiconductor-on-insulator structures

The first part of this paper deals with the standard etching techniques (Secco, Schimmel, Wright etch…) used for defects delineation in Si, SiGe, Ge and in new engineered substrates made from these starting materials, such as Silicon-on-Insulator (SOI), strained and extra-strained Silicon-on-Insulator (sSOI and XsSOI) and Ge-on-Insulator (GeOI). We focus in the second part on the new, chromium-free etching techniques which have recently been developed: chemical solutions containing other oxidizing agents (such as organic peracids, additional compounds such as bromine, iodine etc.) and gaseous HCl etching. We compare the performances of standard etching solutions with those of chromium-free etching techniques and list the specificities of the different techniques. Finally, we attempt to link defect etching results with those coming from physical characterization techniques (such as Raman spectroscopy, X-ray diffraction and Pseudo-MOSFET mobility measurements). A few similar studies can be found in the literature. Extensive work is however still necessary to establish a proper correlation between selective etching and those techniques. Up to now, defect selective etching techniques are the most sensitive ones for an accurate evaluation of crystalline quality.