Method for manufacturing semiconductor structure and semiconductor structure thereof

A method of manufacturing a semiconductor structure, comprising:

• forming a first recess and a second recess adjacent to and separated from the first recess in a substrate;
• filling the first recess and the second recess with a sacrificial layer;
• forming a patterned layer over the sacrificial layer and the substrate;
• patterning the sacrificial layer using the patterned layer as a mask, wherein a portion of the substrate between the first recess and the second recess, an upper portion of a first sidewall of the first recess proximal to the portion of the substrate, and an upper portion of a second sidewall of the second recess proximal to the portion of the substrate are exposed;
• performing an etching operation on the sacrificial layer and the substrate using the patterned layer as a mask;
• and
• forming a dielectric layer in the first recess and the second recess, wherein the dielectric layer covers the portion of the substrate between the first recess and the second recess.

A method of manufacturing a semiconductor structure, comprising:

• forming a first trench between active areas of a substrate, wherein the first trench extends from a first surface of the substrate;
• forming a first layer over the substrate and filling the trenches;
• forming a second layer over the first layer, wherein an opening of the second layer exposes a portion of the first trench and a portion of the substrate adjacent to the first trench from a top-view perspective;
• patterning the first layer using the second layer as a mask, wherein the patterning of the first layer stops above a bottom surface of the first trench;
• performing a low-selective etching operation using the second layer as a mask, thereby defining a second surface of the portion of the substrate below and substantially parallel to the first surface;
• and
• forming a dielectric layer filling the first trench and covering the second surface of the portion of the substrate.