Semiconductor device with air gap therein and manufacturing method thereof

A semiconductor device manufacturing method comprising:

• forming a line-and-space structure on a substrate;
• forming a first film on a sidewall and upper surface of a line of the line-and-space structure by an insulating film material to have a thickness less than half of a width of a space;
• selectively removing the first film to expose a top surface of the line while having the first film remain on the sidewall;
• covering the line-and-space structure by a coating film forming method with a material showing low wettability to the first film to form a second film which extends across the line-and-space structure and is in direct contact with the entire to surface of the line;
• and
• hardening the second film by a heat treatment.