High-electron-mobility transistors including a tiered field plate

A structure for a high-electron-mobility transistor, the structure comprising:

• a gate;
• and
• a gate electrode including a metal layer, the metal layer including a bottom section on the gate and a first plurality of side sections coupled to the bottom section, and the first plurality of side sections intersecting at a first plurality of corners.

A method comprising:

• forming an opening in a dielectric layer, wherein the dielectric layer includes a top surface, and the opening includes a first tiered sidewall and a second tiered sidewall opposite to the first tiered sidewall;
• and
• forming a field plate including a metal layer inside the opening in the dielectric layer, wherein the metal layer includes a first section, a second section connected to the first section, a third section, and a fourth section connected to the third section, the first section is positioned on a first portion of the first tiered sidewall between the second section and the top surface of the dielectric layer, the third section is positioned on a first portion of the second tiered sidewall between the fourth section and the top surface of the dielectric layer, the first section is coplanar with the third section, the first section and the third section having a first width, the second section is coplanar with the fourth section, and the second section and the fourth section having a second width that is equal to the first width.