Semiconductor structure and method of forming the same

A method of forming a semiconductor structure, the method comprising:

• forming an aluminum gallium nitride (AlGaN) layer over a gallium nitride (GaN) layer, wherein a carrier channel is located between the GaN layer and the AlGaN layer;
• forming a source feature and a drain feature over the AlGaN layer;
• forming a gate dielectric layer over the AlGaN layer, wherein the gate dielectric layer is over a top surface of the source feature and over a top surface of the drain feature;
• implanting a fluorine-containing compound into a portion of the gate dielectric layer;
• and
• forming a gate electrode over the portion of the gate dielectric layer.

A method of forming a semiconductor structure, the method comprising:

• forming a second III-V compound layer over a first III-V compound layer, wherein a carrier channel is located between the first III-V compound layer and the second III-V compound layer;
• forming a source feature and a drain feature over the second III-V compound layer;
• forming a gate dielectric layer over the second III-V compound layer, wherein the gate dielectric layer is over a top surface of the source feature and over a top surface of the drain feature, and a portion of the gate dielectric layer is in direct contact with the second III-V compound layer;
• implanting a fluorine-containing compound into the portion of the gate dielectric layer with fluorine;
• and
• annealing the portion of the gate dielectric layer containing the fluorine-containing compound.