Method of manufacturing semiconductor structure with improved etching process

A method of manufacturing a semiconductor structure, comprising:

• providing a substrate;
• forming a first layer over the substrate;
• patterning the first layer to form a first patterned layer and to expose portions of the substrate;
• forming a conformal layer over the first patterned layer and the substrate;
• forming a second layer over the conformal layer, wherein the second layer at least fills between different portions of the first patterned layer;
• removing portions of the conformal layer and the second layer disposed over the first patterned layer to form a patterned conformal layer and a second patterned layer, wherein top surfaces of the first patterned layer, the second patterned layer and the patterned conformal layer are substantially coplanar;
• performing a first etching to form a first recess on the first patterned layer and a second recess on the second patterned layer, wherein each of the first recess and the second recess is surrounded by the patterned conformal layer;
• and
• performing a second etching to remove vertical portions of the patterned conformal layer to separate the first patterned layer and the second patterned layer with a plurality of gaps.