FINFET WITH DUAL WORKFUNCTION GATE STRUCTURE

摘要

Disclosed are a method to fabricate a semiconductor device having a two-layered gate structure, and so fabricated a semiconductor. The gate threshold voltage can be tuned by using two metal layers with different workfunctions, disposed over a fin structure on a substrate and extending in parallel to the current flow direction in the fin structure, and by varying individual thicknesses of the layer so as to change the relative coverage of the fin structure by the layers. The method may comprise providing a substrate having a fin structure, depositing first and second gate metals, and forming a gate dielectric layer. The method may further comprise determining the workfunctions of the first and second gate metals and their thicknesses to achieve a desired gate threshold voltage. Forming the first and second gate metal layers and the dielectric layer may use processes such as deposition, epitaxial growth, CMP, or selective etching.

主权项

1. A method of fabricating a semiconductor device, comprising:
providing a substrate having a fin structure, the fin structure having a height in a substantially perpendicular direction to the substrate, and having upper and lower portions along the height, the lower portion closer to the substrate than the upper portion; and forming a gate structure in a manner so that the gate structure wraps around a portion of the fin structure, wherein forming the gate structure comprises:
forming a gate dielectric layer around the fin structure; andforming a gate electrode layer over the gate dielectric layer, wherein forming the gate electrode layer comprises:
forming a first gate metal layer along both sides of the lower portion of the fin structure, the first gate metal layer having a first workfunction, andforming a second gate metal layer disposed over the first gate metal layer and wrapped around the upper portion of the fin structure, the second gate metal layer having a second workfunction, wherein the first and the second workfunctions are different.