GaN HEMT (High Electron Mobility Transistor) device with gradually-changed doped stepped fluorine ion terminal

The invention belongs to the technical field of power semiconductors, and relates to a GaN HEMT (High Electron Mobility Transistor) device with a gradually-varied doped stepped fluorine ion terminal. Stepped grooves of which the widths are sequentially reduced and the depths are sequentially shallower along with window widths from a source electrode to a drain electrode are formed by utilizing a load effect of dry etching, and an under-gate fluorine ion region and a gradually-changed doped stepped fluorine ion terminal which are realized by one-time fluorine ion implantation are introduced, so that enhancement mode and high voltage resistance are realized at the same time. The gradually-changed doped stepped fluorine ion terminal can effectively reduce the electric field peak near the grid electrode, introduces a new electric field peak at the terminal end near the drain electrode, optimizes the electric field distribution on the surface of the drift region, and improves the withstand voltage of the device. M