Fabrication process for a semiconductor device having a metal oxide dielectric material with a high dielectric constant, annealed with a buffered anneal process

Abstract

A method of forming an annealed high-K metal oxide transistor gate structure is disclosed. A metal oxide layer is formed over a semiconductor substrate. The metal oxide layer undergoes a buffered annealed process in an oxygen atmosphere to anneal the metal oxide layer at or below the thermodynamic chemical equilibrium of SiO/SiO₂ and at or above the thermodynamic chemical equilibrium of the metal oxide layer.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to the field of semiconductor devices, and more specifically to a fabrication process for a semiconductor device having a metal oxide dielectric material with a high dielectric constant. [0003] 2. Description of the Related Art [0004] As the dimensions of the MOS transistor are scaled down, the thickness of its gate oxide, typically SiO2, decreases accordingly. Reducing the SiO2 layer to an ultrathin thickness results in charge carrier leakage by tunneling conduction as the ultrathin SiO2 gate oxide layer no longer functions as an effective insulator. [0005] Tunneling conduction also causes a faster dissipation of stored charge resulting in, for example, shortened battery life in portable devices such as cellular telephones and laptop computers. Typically, the gate dielectric layer used in a MOS transistor is an SiO2 layer which has a dielectric constant of 3.9. Alternative gate oxide m...

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Benefits of technology

[0014] The present invention addresses the noted problems above and provides a method of fabricating a semiconductor device such as a MOSFET (metal-oxide semiconductor field effect transistor) utilizing a metal oxide dielectric material possessing a dielectric constant greater than SiO2. Specifically, the invention provides

Problems solved by technology

Reducing the SiO2 layer to an ultrathin thickness results in charge carrier leakage by tunneling conduction as the ultrathin SiO2 gate oxide layer no longer functions as an effective insulator.

Tunneling conduction also causes a faster dissipation of stored charge resulting in, for example, shortened battery life in portable devices such as cellular telephones and laptop computers.

However, current high-K dielectric gate layers result in devices that suffer from low carrier mobility and drive current.

Such processing steps can result in an undesirably thick SiO2 interfacial layer due to reoxidation of the Si/SiO2 (silicon/silicon dioxide) interface.

Therefore, the presence of a significantly reoxidized thicker SiO

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