Roughness Analysis of the Critical Dimension by Using Spectroscopic Ellipsometry

In semiconductor electronics applications, observation of the linewidth roughness (LWR) or the critical dimension roughness will become increasingly important. In this article, we study to analyze the roughness of a grating structure by using spectroscopic ellipsometry. A simple 1D patterned c-Si grating structure was measured from the zeroth-order diffraction response at a fixed angle of incidence, which result agreed with a theoretical prediction made by using a rigorous coupled-wave analysis (RCWA) calculation with an effective-medium approximation (EMA) for a structure with roughness.