SUBSTRATE COVERED WITH THIN FILM OF FERROELECTRIC SUBSTANCE, ITS MANUFACTURE, AND NONVOLATILE MEMORY CONSTRUCTED THE SUBSTRATE

摘要

PURPOSE: To enable a thin-film-coated substrate having a solid, flat surface and showing great residual spontaneous polarization to be manufactured through a low temperature process by forming a buffer layer, a growth layer, and a thin film of a ferroelectric substance represented by a specific chemical formula on the substrate in sequence. CONSTITUTION: The surface of a silicon single-crystal wafer substrate 1, for example, is thermally oxidized to form an SO2 layer 2. Thereover a thin film of Ta as a bonding layer 3 and a thin film of Pt as a lower electrode layer 4 are both formed by sputtering. Further, a thin film of titanium as a buffer layer 5 and a thin film of Bi4 Ti3 O12 as a growth layer 6 are formed by MOCVD. After the supply of raw material is temporarily stopped, the substrate temperature is lowered to 400 deg.C, Bi4 Ti3 O12 is formed as a thin film 7 of ferroelectric substance, and a Pt electrode film is formed thereover as an upper electrode layer 8 by vacuum evaporation to provide the substrate covered with time thin film of ferroelectric substance. For the thin film of ferroelectric substance, a ferroelectric substance with a layered crystal structure is generally usable.