Patent ID: 8202794

Claim:
A method of manufacturing an Ohmic electrode structure, wherein the Ohmic electrode structure comprises: a substrate; an electron transit layer formed of a first semiconductor layer formed on a main face of the substrate; an electron supply layer, forming a heterojunction with the electron transit layer at a heterointerface, formed on the electron transit layer, the electron supply layer including a second semiconductor layer having electron affinity smaller than that of the first semiconductor layer; a two-dimensional electron layer having a two-dimensional electron gas, induced from the heterointerface and extending into the electron transit layer; and an Ohmic electrode of a metal material disposed in a recess surrounded by side faces forming sidewalls of depression and a bottom face connecting lower ends of the side faces, said bottom face of said recess being disposed lower than the heterointerface, one end portion of the Ohmic electrode on the main face side penetrating the electron supply layer from a top face of the electron supply layer and being positioned in said electron transit layer, at a depth equal to or greater than the heterointerface, but not exceeding the depth of the electron transit layer, and, at a point where said Ohmic electrode contacts the heterointerface, an angle on an acute-angle side made by a tangential plane of the surface of the Ohmic electrode with a plane of extension of the heterointerface being greater than 0 and less than or equal to 56, and wherein the method comprises the steps of: forming said recess by etching a region for formation of said Ohmic electrode, from a side of said electron supply layer to a depth equal to or greater than said heterointerface, but to a depth not exceeding said electron transit layer; burying said recess with metal material; and performing heat treatment of metal material burying said recess.