Semiconductor device and method for manufacturing the same

A method for manufacturing a semiconductor device, comprising the steps of:

• forming a plurality of Fins extending along a first direction on a substrate;
• forming a dummy gate stack structure extending along a second direction on the Fins;
• forming doped source/drain regions in and/or on the Fins at both sides of the dummy gate stack structure along the first direction, and forming channel regions in a part of the Fins between the source/drain regions beneath the dummy gate stack structure;
• forming an inter-layer dielectric layer on the substrate, and selectively etching to remove the dummy gate stack structure and leave the gate trenches in the inter-layer dielectric layer;
• prior to forming the gate stack structure, implementing ion implantation to form a punch through stop layer in the middle and at the bottom of the Fins;
• depositing a gate insulating layer and a poly-semiconductor layer in turn in the gate trenches and on top of the inter-layer dielectric layer;
• doping the poly-semiconductor layer to form a doped poly-semiconductor layer as a gate conductive layer;
• and
• implementing activation and annealing to activate the dopants in the source/drain regions and the gate conductive layer at the same time, so as to facilitate the dopants to be uniformly distributed in the gate conductive layer.