Nitride-based semiconductor device and method for manufacturing the same

A method for manufacturing a nitride-based semiconductor device, comprising:

• forming an epitaxy structure on a silicon-based substrate;
• forming an oxide structure on the epitaxy structure;
• forming a mask layer having an opening on the epitaxy structure such that at least one portion of the oxide structure is exposed from the opening in a chamber;
• performing a first reactive-ion etching process in the chamber by using a first halogen-based gas to remove the exposed at least one portion of the oxide structure such that a portion of the epitaxy structure is exposed;
• and
• performing a second reactive-ion etching process in the chamber by using a second halogen-based gas different than the first halogen-based gas to remove the exposed portion of the epitaxy structure such that a portion of the silicon-based substrate is exposed.

A nitride-based semiconductor device, comprising:

• a silicon-based substrate;
• an epitaxy structure disposed on the silicon-based substrate, wherein the epitaxy structure has a first inner sidewall and a second inner sidewall at above the first inner sidewall and connected to the first inner sidewall, and the first inner sidewall and the second inner sidewall have different roughness and are oblique with respect to the silicon-based substrate;
• an oxide structure disposed on the epitaxy structure, wherein the oxide structure has an inner sidewall connected to the second inner sidewall and oblique with respect to the silicon-based substrate;
• and
• a conductor filling extending from a position beneath the epitaxy structure to a position over the oxide structure.