Taiwan Semiconductor Manufacturing Comp. Ltd.

Hui-Ling Shang

Chang-Miao Liu

Xu-Sheng Wu

A semiconductor device includes a substrate, a gate stack over the substrate and a gate spacer on a sidewall of the gate stack. The gate spacer includes an outer spacer and an inner spacer between the gate stack and the outer spacer. The outer spacer and the inner spacer have same k-value reduction impurities, and a concentration of the k-value reduction impurities in the inner spacer is greater than a concentration of the k-value reduction impurities in the outer spacer.

Dielectric constant reduction of gate spacer

A method includes forming a dummy gate structure over a substrate, forming a plurality of gate spacers respectively on opposite sidewalls of the dummy gate structure and having a first dielectric constant, removing the dummy gate structure to form a gate trench between the gate spacers, forming a dopant source layer to line the gate trench, annealing the dopant source layer to diffuse k-value reduction impurities from the dopant source layer into the gate spacers to lower the first dielectric constant of the gate spacers to a second dielectric constant, and forming a replacement gate stack in the gate trench.

Growing community of inventors

Hsinchu County, Taiwan

Hui-Ling Shang