Fin Gate-All-Around Structure for Stronger Channel Control

The patent transitions from planar transistor geometry to a three-dimensional FinFET structure with a vertical fin channel. The gate wraps around the fin channel in a U-shape configuration, providing control from the top and both sidewalls. This dimensional change from 2D planar to 3D vertical structure enhances gate control over the channel while enabling higher integration density, as the vertical fin allows for increased effective channel width without increasing the planar footprint.

The patent segments the transistor structure into distinct functional regions: the vertical fin channel, the U-shaped gate wrapping around the fin, source/drain regions at the base of the fin, and isolation structures. This segmentation allows each component to be optimized and manufactured separately using specialized processes such as selective epitaxial growth for the fin, conformal deposition for the gate, and precise doping for source/drain regions, thereby managing manufacturing complexity while achieving superior gate control.

The patent applies different material properties and structural characteristics to different regions of the transistor to optimize local performance. The fin channel may use different semiconductor materials with specific bandgap properties, the gate uses high-k dielectric materials with specific permittivity values, and source/drain regions are doped with specific concentrations. This local optimization allows the gate-all-around structure to provide excellent channel control while managing the DC current characteristics to maintain proper AC current performance and overall device balance.