3D field effect transistor (FET) device having u-shaped channel structure

A semiconductor device comprising:

• a substrate comprising a working surface;
• a transistor formed in the substrate, the transistor comprising:
• a complex channel structure which is vertically arranged with respect to the working surface, the complex channel structure comprising first and second source-drain (S-D) ends provided in a plane extending along the working surface to define an opening to a bounded region of the complex channel structure,
• a gate dielectric layer formed on the complex channel structure within the bounded region,
• a gate metal layer formed on the gate dielectric layer within the bounded region to form the transistor;
• and
• a plurality of complex channel structure transistors formed in the substrate,
• wherein:
• the substrate and the plurality complex channel transistors collectively define a first transistor sheet;
• and
• a second transistor sheet is located above the first transistor sheet, the second transistor sheet further comprising:
• a second substrate disposed on the first substrate and having a second working surface opposite the first working surface;
• and
• a second plurality of complex channel transistors located within the second substrate, each having first and second S-D ends.