A method includes forming a stack of nanostructures over a substrate; forming a source/drain opening adjacent the stack of nanostructures; forming a semiconductor layer in the source/drain opening; forming an amorphous semiconductor layer by performing an ion implantation on the semiconductor layer; and forming a recrystallized source/drain by annealing the amorphous semiconductor layer.

Embodiments with present disclosure provide a method for forming a semiconductor device including recrystallized source/drain regions. The recrystallized source/drain regions may be formed by a high temperature treatment after epitaxial process.

A semiconductor structure and a method of forming the same are provided. In an embodiment, an exemplary semiconductor method includes forming a fin-shaped structure extending from a substrate, the fin-shaped structure includes a number of channel layers interleaved by a number of sacrificial layers, recessing a source/drain region to form a source/drain opening, performing a PAI process to amorphize a portion of the substrate exposed by the source/drain opening, forming a tensile stress film over the substrate, performing an annealing process to recrystallize the portion of the substrate, the recrystallized portion of the substrate includes dislocations, forming an epitaxial source/drain feature over the source/drain opening, and forming a gate structure wrapping around each of the plurality of channel layers. By performing the above operations, dislocations are controllably and intentionally formed and carrier mobility in the number of channel layers may be advantageously enhanced, leading to improved device performance.

An n-type metal oxide semiconductor transistor includes a gate structure, two source/drain regions, two amorphous portions and a silicide. The gate structure is disposed on a substrate. The two source/drain regions are disposed in the substrate and respectively located at two sides of the gate structure, wherein at least one of the source/drain regions is formed with a dislocation. The two amorphous portions are respectively disposed in the two source/drain regions. The silicide is disposed on the two source/drain regions, wherein at least one portion of the silicide overlaps the two amorphous portions.