International Business Machines Corporation
Nanosheet transistors with different gate dielectrics and workfunction metals

Abstract:

Methods of forming semiconductor devices include patterning a stack of layers that includes channel layers, n-type doped first sacrificial layers between the channel layers, and carbon-doped second sacrificial layers between the channel layers and the first sacrificial layers, to form one or more device regions. The first sacrificial layers and the second sacrificial layers are recessed relative to the channel layers with distinct respective etches to produce a flat, continuous, and vertical surface from sidewalls of the first sacrificial layers and respective second sacrificial layers. Inner spacers are formed in recesses formed by the recessing of the first sacrificial layers and the second sacrificial layers. The first sacrificial layers and the second sacrificial layers are etched away to leave the channel layers suspended.