Replacement body finfet for improved junction profile with gate self-aligned junctions

Abstract

The invention provides a replacement body FINFET for improved junction profile with gate self-aligned junctions. After forming an epitaxial semiconductor layer on portions of a semiconductor located on opposite sides of a sacrificial gate structure, dopants from the epitaxial semiconductor layer are diffused into the semiconductor fin to form a dopant-containing semiconductor fin. A sacrificial gate stack is removed to provide a gate cavity that exposes a portion of the dopant-containing semiconductor fin. The exposed portion of the dopant-containing semiconductor fin is removed to provide an opening underneath the gate cavity. A channel which is undoped or less doped than remaining portions of the dopant-containing semiconductor fin is epitaxially grown at least from the sidewalls of the remaining portions of the dopant-containing semiconductor fin. Abrupt junctions are thus formed between the channel region and the remaining portions of the dopant-containing semiconductor fin.

Description

technical field [0001] The present application relates to semiconductor device fabrication, and more particularly to the fabrication of fin field effect transistors (FinFETs) having abrupt junctions that are self-aligned to gate electrodes. Background technique [0002] FinFETs are a desired device architecture due to their fast switching times and high current densities. In its basic form, a FinFET includes a source region, a drain region, and a fin-shaped channel region between the source and drain regions. A gate electrode formed over the fin regulates the flow of electrons or holes between the source region and the drain region. Gate spacers are usually formed on sidewalls of the gate electrode to control the gate-to-source / drain spacing. [0003] As FinFETs shrink further, designers are faced with a trade-off between short-channel effects and source / drain resistance. Larger source / drain doping to reduce resistance increases junction depth and associated short channel...

AI Technical Summary

Problems solved by technology

The channel region of the FinFET may also be doped due to the difficulty in achieving precise control of the dopant profile when using a diffusion process

This channel doping in FinFETs results in reduced carrier mobility and is therefore detrimental to performance

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