As planar semiconductor devices are scaling down, short channel effects become more significant. Therefore, three-dimensional (3D) semiconductor devices, such as, FinFETs (Fin Field Effect Transistors) are proposed. In general, a FinFET includes a fin formed vertically on a substrate and a gate stack intersecting with the fin. Therefore, conductive channels may be formed on sidewalls of the fin.
In general, a fin may be acquired by patterning a substrate or a semiconductor layer further formed on a substrate. However, due to limitations of the patterning process, such as, lithography, Reactive Ion Etching (RIE), or the like, the acquired fin usually has a relatively large Line Edge Roughness (LER).