Quantum thin line producing method and semiconductor device

Abstract

A Si protruding portion is formed on a Si substrate by opportunely using the general film forming technique, photolithographic technique and etching technique. A second oxide film is formed to fill up a space between Si protruding portions, and the surface is flattened by the CMP method or the like. Then, the second oxide film is subjected to anisotropic etching to form a Si exposed portion at the top of the Si protruding portion. A Si thin line is made to grow in this Si exposed portion, and then a third oxide film for isolating the Si thin line from the Si substrate is formed through oxidation. A quantum thin line is thus formed at low cost without using any special technique of SOI or the like. Furthermore, the substrate surface is flattened, allowing the formation of a single electron device or a quantum effect device to be easy. The quantum thin line is isolated from the Si substrate by the third oxide film, completely confining the electron. With this arrangement, a quantum thin line that has good substrate surface flatness and is able to form a complete electron confining region is formed by using a semiconductor substrate of a Si substrate or the like.