The invention provides a 
semiconductor structure and a method for forming the 
semiconductor structure. The method comprises a step of providing a substrate and fins protruding from the substrate, wherein the materials of the fins contain 
germanium elements, an 
isolation layer covering partial sidewalls of the fins are on the substrate, and the top of the 
isolation layer is lower than the tops of the fins, a step of forming a dummy 
gate oxide layer on the tops and sidewalls of the fins exposed by the 
isolation layer by using the 
atomic layer deposition process, wherein the process temperature of the 
atomic layer deposition process is a first temperature, a step of forming a dummy gate across the fins, wherein the dummy gate covers the surface of a dummy 
gate oxide layer, a step of forming adielectric layer on the isolation layer, wherein the 
dielectric layer covers a sidewall of the dummy gate and exposes a top wall of the dummy gate, a step of removing the dummy gate and the dummy 
gate oxide layer and exposing the tops and partial sidewalls of the fins, and a step of forming an 
interface layer on the exposed tops and sidewalls of the fins, wherein the process temperature of forming the 
interface layer is a second temperature which is lower than or equal to the first temperature. According to the invention, the 
germanium elements in the fins can be prevented from diffusing intothe 
interface layer, therefore, the interface characteristics between the interface layer and the fins can be improved, and the carrier mobility is enhanced.