THIN FILM CAPACITOR AND SEMICONDUCTOR MEMORY

摘要

PURPOSE: To provide a thin film capacitor in which a temperature range in which a dielectric film indicates ferroelectricity is large and the value of a residual polarization is sufficiently large in practice. CONSTITUTION: A thin film capacitor comprises a conductive substrate 5 made of a conductive material having a crystalline structure in which a front surface is the surface (001) of a tetragonal crystal, a dielectric film 3 made of (Ba0.85 Sr0.15 )TiO3 (tetragonal crystal) having a perovskite crystalline structure formed on the substrate 5, and an upper electrode 4 formed on the film 3. The original Curie temperature of the dielectric material is 150 deg.C or lower, and the original lattice constant ad of the dielectric material represented by the a axis length of the perovskite structure and the original lattice constant as of the conductive material represented by by the a axis length of the tetragonal crystal structure satisfy the relation formula of 1.002<=ad /as <=1.015.