Active area patterning for CFET: nanosheet etch

Nanosheet device architectures such as complementary FET (CFET) are candidates to replace FinFET, improving device performance while allowing a higher density of devices for a similar footprint. Two main challenges can be highlighted in the definition of the active area (AA) patterning for CFET. First the presence of stacked nanosheets generates the need for a higher aspect-ratio compared to FinFET. Secondly, the nanosheets layers, composed of silicon and silicon-germanium with varied thicknesses and concentrations, require new approaches in terms of process definition and control. The first results of an active area patterning for a full CFET device have been demonstrated at imec. Thicker nanosheet stacks are patterned opening the path to the creation of a complete CFET device.