A method and apparatus is provided for conveying lime slurry, removing and controlling the amount of grit, and feeding lime slurry, wherein the lime slurry moves through a recirculation loop, and wherein gravity removal of grit from the lime slurry takes place. Using one such method, a composite bond wire is produced for use in an integrated circuit. A bit line interlayer insulating layer is disposed to cover the bit line patterns. Further, with excellent performances, they are suitable to replace the existing antioxidants. For example, in an intermediate zone, a resistant layer for suppressing heat transfer from the fins to the opposite wall is formed between the opposite wall and the fins.