Methods for integrating replacement metal gate structures

Abstract

Methods and associated structures of forming a microelectronic device are described. Those methods comprise providing a substrate comprising a first transistor structure comprising an n-type gate material and second transistor structure comprising a p-type gate material, selectively removing the n-type gate material to form a recess in the first gate structure, and then filling the recess with an n-type metal gate material.

Description

FIELD OF THE INVENTION [0001] The present invention relates to the field of microelectronic devices, and more particularly to methods of fabricating metal gate transistors. BACKGROUND OF THE INVENTION [0002] Microelectronic devices are often manufactured in and on silicon wafers and on other types other substrates. Such integrated circuits may include millions of transistors, such as metal oxide semiconductor (MOS) field effect transistors, as are well known in the art. MOS transistors typically comprise source, drain and gate regions, in which the gate material may typically comprise polysilicon. Polysilicon gates, however, can be susceptible to depletion effects, wherein an electric field applied to a polysilicon gate sweeps away carriers (holes in a p-type doped polysilicon, or electrons in an n-type doped polysilicon) so as to create a depletion of carriers in the area of the polysilicon gate near an underlying gate dielectric of the transistor. The depletion effect can add to t...

AI Technical Summary

Benefits of technology

The present invention provides a method and structure for incorporating both metal gate and polysilicon gate transistors in the same microelectronic device. This is achieved by selectively removing the polysilicon gate material from one transistor structure and replacing it with metal gate material in another transistor structure. The method and structure allow for the use of silicon germanium source and drain regions in the transistors, which enhance their performance. The invention provides a reliable and cost-effective process for incorporating both metal and polysilicon gates in the same device.

Problems solved by technology

Polysilicon gates, however, can be susceptible to depletion effects, wherein an electric field applied to a polysilicon gate sweeps away carriers (holes in a p-type doped polysilicon, or electrons in an n-type doped polysilicon) so as to create a depletion of carriers in the area of the polysilicon gate near an underlying gate dielectric of the transistor.

Typical prior art microelectronic processes, however, do not incorporate both metal gates and polysilicon gates within the same device or integrated circuit.

This is due, in part, to the complexity and cost of developing a microelectronic process that can reliably form both a metal gate structure and a polysilicon gate structure within the same microelectronic device or integrated circuit.

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