This report describes the first demonstration of a 100nm T-gate for the Superlattice Castellation Field Effect Transistor (SLCFET) amplifier. The SLCFET amplifier device utilizes a superlattice of GaN/AlGaN channels, which enables a high charge density and low source resistance. A three-dimensional T-gate structure provides electrostatic control of the channels while maintaining high gain. Improvements to the T-gate process have allowed for the scaling of the gate down to 100nm while maintaining excellent gate control, with an on to off current ratio exceeding 107. This gate scaling allows the device to reach FT / FMAX of 70/110 GHz with full passivation to maintain compatibility with the productionized SLCFET switch process.