Method and system for improving uniformity of thickness of SiGe

The invention discloses a method and system for improving the uniformity of the thickness of SiGe. A process is adopted to form a protection layer to cover a small pit between two regions of a semiconductor material; in an etching process, the protection layer can protect the small pit from being etched and can assist in reducing the material loss of a silicon (Si)-shallow trench isolation (STI) substrate; and selective coverage is provided, so that the Si-STI substrate and height of a Si-STI interface can be protected. With the method and system adopted, desired geometry can be obtained, so that a silicon-germanium (SiGe) layer with uniform thickness can be formed near the small pit.