Method of forming an insulated-gate field-effect transistor with metal spacers

Abstract

An IGFET with metal spacers is disclosed. The IGFET includes a gate electrode on a gate insulator on a semiconductor substrate. Sidewall insulators are adjacent to opposing vertical edges of the gate electrode, and metal spacers are formed on the substrate and adjacent to the sidewall insulators. The metal spacers are electrically isolated from the gate electrode but contact portions of the drain and the source. Preferably, the metal spacers are adjacent to edges of the gate insulator beneath the sidewall insulators. The metal spacers are formed by depositing a metal layer over the substrate then applying an anisotropic etch. In one embodiment, the metal spacers contact lightly and heavily doped drain and source regions, thereby increasing the conductivity between the heavily doped drain and source regions and the channel underlying the gate electrode. The metal spacers can also provide low resistance drain and source contacts.