Gas sensor and manufacturing method thereof

A method for manufacturing a gas sensor, comprising:

• laminating a first membrane on a substrate;
• forming a heating structure on the first membrane;
• laminating a second membrane on the first membrane and the heating structure;
• forming a second membrane etching hole by patterning the second membrane;
• forming a sensing electrode on the second membrane;
• forming a first membrane etching hole in the first membrane through the second membrane etching hole;
• and
• etching a portion of the substrate through the first membrane etching hole and the second membrane etching hole,
• wherein the forming of a portion of the substrate comprises forming an isolation space by allowing a portion of a top surface of the substrate to be recessed downward,
• the first membrane etching hole has a diameter of about 3 μm to about 20 μm,
• wherein the substrate further comprises an inner sidewall connecting the recessed surface and another portion of the top surface of the substrate,
• wherein the substrate further comprises a plurality of columns penetrating the isolation space,
• each of the plurality of columns vertically extends to connect the bottom surface of the first membrane with the recessed surface, and
• each of the plurality of columns is spaced apart from the inner sidewall of the substrate.