In this paper we discuss a multi-scale method for the process simulation at the atomic resolution applied to the plasma etching. We demonstrate that accurate prediction of the micro-structure modifications, as a function of the equipment parameters, can be achieved by coupling two simulation approaches modeling phenomena at different length scales. Focusing on the etching processing of nano-patterned silicon samples in in HBr/O $ _ {2} $-type plasma the main the ingredients of the numerical method are highlighted: a) ...