Semiconductor device

A semiconductor device, comprising:

• a first nitride semiconductor layer having a first surface;
• a second nitride semiconductor layer on the first surface of the first nitride semiconductor layer and having a larger bandgap than the first nitride semiconductor layer;
• a first electrode above the second nitride semiconductor layer in a first direction orthogonal to the first surface and electrically connected to the first nitride semiconductor layer;
• a second electrode above the second nitride semiconductor layer in the first direction and electrically connected to the first nitride semiconductor layer, the second electrode being separated from the first electrode in a second direction parallel to the first surface;
• a gate electrode with a planar portion that is between the first electrode and the second electrode in the second direction;
• a gate field plate electrode above the planar portion of the gate electrode in the first direction and electrically connected to the gate electrode, the gate field plate electrode including a central portion directly above the planar portion of the gate electrode in the first direction;
• a first field plate electrode above the second nitride semiconductor layer in the first direction at a position that is between the gate field plate electrode and the second electrode in the second direction, the first field plate electrode being electrically connected to the first electrode;
• and
• a second field plate electrode including an upper planar portion and a projecting portion that extends from the upper planar portion towards the first nitride semiconductor layer in the first direction, the projecting portion being between the first field plate electrode and the gate field plate electrode in the second direction and electrically connected to the first electrode, wherein
• a distance along the first direction from the first nitride semiconductor layer to the projecting portion of the second field plate electrode is greater than zero but shorter than a distance along the first direction from the first nitride semiconductor layer to an end portion of the gate field plate electrode that protrudes the most along the second direction towards the second electrode,
• the distance along the first direction from the first nitride semiconductor layer to the projecting portion of the second field plate electrode is shorter than a distance along the first direction from the first nitride semiconductor layer to an end portion of the first field plate electrode on a first electrode side of the first field plate electrode,
• a lowermost portion of the second field plate electrode in the first direction is separated from the second nitride semiconductor layer in the first direction by a portion of an interlayer insulating film, and
• an end portion of the planar portion of the gate electrode is overlapped with the projecting portion of the second field plate electrode in the first direction and between the projecting portion of the second field plate electrode and the second nitride semiconductor layer in the first direction.