The invention discloses a
semiconductor structure and a forming method thereof, and the method comprises the steps: providing a substrate which comprises a substrate and a fin part protruding out of the substrate, the substrate comprises a first region used for forming a first device and a second region used for forming a second device, and the working
voltage of the first device is greater than the working
voltage of the second device; forming a first
gate oxide layer covering the fin portions of the first region and the second region in a shape-preserving manner, the first
gate oxide layer located in the second region being used for forming a
gate dielectric layer of a second device; a second
gate oxide layer covering the first gate
oxide layer in a shape-preserving mode is formed, and the second gate
oxide layer and the first gate
oxide layer located in the first area are used for forming a
gate dielectric layer of the first device; and carrying out
gate dielectric layer
thinning treatment, wherein the gate
dielectric layer
thinning treatment comprises the step of removing the second gate oxide layer in the second region. According to the scheme, the consumption of the fin parts in the second region in the process is reduced, and the width uniformity and height uniformity of the fin parts in the first region and the second region are further improved.