Abstract: Disclosed is a semiconductor device and a method for fabricating such semiconductor device, specifically a High Electron Mobility Transistor (HEMT) with a back barrier layer for blocking electron leakage and improve threshold voltage. In one embodiment, a semiconductor device, includes: a Gallium Nitride (GaN) layer; a front barrier layer over the GaN layer; a source electrode, a drain electrode and a gate electrode formed over the front barrier layer; a 2-Dimensional Electron Gas (2-DEG) in the GaN layer at a first interface between the GaN layer and the front barrier layer; and a back barrier layer in the GaN layer, wherein the back barrier layer comprises Aluminum Nitride (AlN).

Abstract: A semiconductor device includes a semiconductor substrate, an isolation feature, gate lines, and a first gate structure. The isolation feature is over the semiconductor substrate and surrounding an active region of the semiconductor substrate. The gate lines extend across the active region of the semiconductor substrate. The first gate structure is over the isolation feature. The first gate structure comprises a first gate line, a second gate line, and a first bridge portion, the first and second gate lines are substantially parallel with the gate lines, and the first bridge portion connects the first gate line to the second gate line.