Semiconductor structure with improved channel stack and method for fabrication thereof

Abstract

A method for fabricating a semiconductor structure with a channel stack includes forming a screening layer (120,110) under a gate of a PMOS transistor element (116) and a NMOS transistor element (106), forming a threshold voltage control layer (122, 112) on the screening layer, and forming an epitaxial channel layer (124) on the threshold control layer. At least a portion of the epitaxial channel layers for the PMOS transistor element and the NMOS transistor element are formed as a common blanket layer. The screening layer (120) for the PMOS transistor element (116) may include antimony as a dopant material that may be inserted into the structure prior to or after formation of the epitaxial channel layer.

Description

technical field [0001] The present disclosure generally relates to semiconductor devices and fabrication processes, and more particularly to a semiconductor structure with an improved channel stack and a method of fabrication thereof. Background technique [0002] Field effect transistors are typically fabricated on semiconductor substrates that are doped to contain mobile charge carriers. The dopant atoms can be electron donors or electron acceptors when incorporated into the semiconductor substrate lattice as a result of the activation process. An activated donor atom transfers weakly bound valence electrons to the material, creating an excess of negative charge carriers. These weakly bound electrons are relatively free to move within the semiconductor substrate lattice, facilitating conduction in the presence of an electric field applied by the gate terminal. Similarly, activated receptors generate mobile positive charge carriers called holes. Semiconductors doped with...

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Problems solved by technology

However, implant tool limitations, required thermal treatment conditions, and material or process variations can easily lead to undesired diffusion of dopant material from the initial implant site, degrading performance or even preventing reliable transistor operation

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