Fabricating method of fin structure with tensile stress and complementary finfet structure

A fabricating method of a fin structure with tensile stress, comprising:

• providing a substrate comprising an N-type transistor region and a P-type transistor region;
• forming two first trenches and two second trenches within the substrate, wherein the first trenches define a fin structure, and the second trenches segment the first trenches;
• performing a flowable chemical vapor deposition process to form a silicon oxide layer in the first trenches and the second trenches;
• planarizing the silicon oxide layer, wherein after planarizing the silicon oxide layer, a top surface of the silicon oxide layer is not lower than a top surface of the fin structure;
• forming a patterned mask layer only within the N-type transistor region, wherein the patterned mask layer only overlaps the silicon oxide layer within the second trenches;
• removing part of the silicon oxide layer by taking the patterned mask layer as a mask to make both the top surface of the silicon oxide layer in the first trenches within the N-type transistor region and the top surface of the silicon oxide layer within the P-type transistor region lower than the top surface of the fin structure;
• and
• removing the patterned mask layer.