Isotropic Etching of Si1-xGex Buried Layers Selectively to Si for the Realization of Advanced Devices

Abstract

The selective removal of a SiGe sacrificial layer in a Chemical Dry Etching (CDE) mode is reported. The process parameters have been optimized in order to minimize the consumption of the surrounding Si in advanced 3D structures. The impact of parameters such as the Ge content, the SiGe layer's thickness or the nature of the mask has also been investigated in order to have a global understanding of the etching mechanisms. The optimal process conditions have been tested on devices of which electrical performances have completed the morphological characterization of the etching recipe.