The semiconductor integrated circuit industry has experienced rapid growth in the past several decades. Technological advances in semiconductor materials and design have produced increasingly smaller and more complex circuits. These material and design advances have been made possible as the technologies related to processing and manufacturing have also undergone technical advances. In the course of semiconductor evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component that can be created using a fabrication process) has decreased. Despite advances in materials and fabrication, in order to further decrease the geometry size, conventional planar MOSFET devices have encounter challenging(s). As such, a variety of devices that are not planar-based or include non-planar components have attracted attention such as, for example, a FinFET device, etc.
Although FinFET devices have demonstrated decent operation performance, it is desired to further improve the performance of FinFET devices, in accordance with the semiconductor evolution. For example, a gate-all-around field-effect-transistor (GAA FET), typically having a gate feature that surrounds or wraps around a respective channel region, was proposed. When compared to the FinFET device, such a GAA FET can further enhance gate controllability over the respective channel region, which in turn provides various advantages over the FinFET devices such as, for example, a lower leakage current, a higher ratio of turn-on current to turn-off current, etc.
However, conventional techniques to make such a GAA FET, more specifically the respective channel region to be wrapped, typically relies on uncontrollable etching processes. As such, the channel region's geometric dimension cannot be well controlled, which results in various uncertainties in terms of a respective critical dimension (typically known as “CD”) of the GAA FET. Thus, conventional techniques to make a GAA FET are not entirely satisfactory.