Patent ID: 9728630
Date: 2017-08-08
CPC Classifications: H01L

Claim:
1. A method of forming a high-electron-mobility field effect transistor, the method comprising: forming a buffer region having a stepped lateral profile, the stepped lateral profile comprising first, second and third cross-sections of the buffer region, the first cross-section being thicker than the third cross-section, the second cross-section interposed between the first and third cross-sections and forming oblique angles with the first and third cross-sections; and forming a buried field plate within the first cross section of the buffer region, forming a barrier region along the stepped lateral profile of the buffer region, the barrier region separated from the buried field plate by a portion of the buffer region, wherein the buffer region is formed from a first semiconductor material and the barrier region is formed from a second semiconductor material, the first and second semiconductor materials having different band-gaps such that an electrically conductive channel comprising a two-dimensional charge carrier gas arises at an interface between the buffer and barrier regions due to piezoelectric effects, wherein the buffer region is formed by an epitaxial growth process, and wherein forming the buried field plate comprises epitaxially growing a second layer of the first or second semiconductor material on a first layer of the first semiconductor material as part of the buffer region, wherein forming the buffer region and the buried field plate comprises: