Transistor comprising a uniform stack of channel material layers

Abstract

Transistor structures comprising a stack of channel material layers may be fabricated from a material stack comprising an uppermost sacrificial material layer over one or more bilayers. Each bilayer includes a sacrificial material layer and a channel material layer. The uppermost sacrificial material layer may ensure an uppermost channel material layer will have substantially the same structure as an underlying channel material layer. A channel portion of all channel material layers may therefore have substantially the same thickness. End portions of all channel material layers may therefore also be both above and below a first gate spacer with a second gate spacer adjacent to a sidewall of the end portions. A channel portion of an underlying one of the channel material layers may have a lesser thickness than that of its end portions. An uppermost channel material layer may advantageously have substantially the same difference in layer thickness between end portions and channel portion.