Semiconductor structure and fabrication method thereof

Abstract

A semiconductor structure is provided. The semiconductor structure includes a substrate, word lines, a first barrier layer and work function control structures. The word lines are located in word line trenches of the substrate. The first barrier layer is disposed on top surfaces of the word lines. The work function control structures are disposed over the word lines. Each work function control structure includes a first doped region and a second doped region, with the first doped region positioned closer to the word lines than the second doped region. The first doped region and the second doped region are composed of a semiconductor material and contain a same dopant species, and the first doped region has a higher dopant concentration than the second doped region.

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