A process for manufacturing a stress-providing structure is applied to the fabrication of a semiconductor device. Firstly, a substrate with a channel structure is provided. A silicon nitride layer is formed over the substrate by chemical vapor deposition in a halogen-containing environment. An etching process is performed to partially remove the silicon nitride layer to expose a portion of a surface of the substrate beside the channel structure. The exposed surface of the substrate is etched to form a recess in the substrate. Then, the substrate is thermally treated at a temperature between 750° C. and 820° C. After the substrate is thermally treated, a stress-providing material is filled in the recess to form a stress-providing structure within the recess. The semiconductor device includes a substrate, a recess and a stress-providing structure. The recess has a round inner surface. The stress-providing structure has a round outer surface.