Transistor with dielectric spacers and field plate and method of fabrication therefor

Abstract

A transistor device includes a semiconductor substrate and a gate structure formed over the substrate. Forming the gate structure may include steps of forming a multi-layer dielectric stack over the substrate, performing an anisotropic dry etch of the multi-layer dielectric stack to form a gate channel opening, forming a conformal dielectric layer over the substrate, performing an anisotropic dry etch of the conformal dielectric layer to form dielectric sidewalls in the gate channel opening, etching portions of dielectric layers in a gate channel region, and forming gate metal in the gate channel region. Dielectric spacers may be similarly formed in a field plate channel opening prior to formation of a field plate of the transistor. By forming dielectric spacers in the gate channel opening, the length of the gate structure can be advantageously decreased.