Patent ID: 8549718

Claim:
A method for producing a ferroelectric oxide structure that has a substrate and a ferroelectric thin-film deposited on the substrate, wherein the crystal structure of the ferroelectric thin-film undergoes phase-transition at a predetermined temperature, and wherein the ferroelectric thin-film has a thickness of greater than or equal to 200 nm and a tetragonal crystal system when the temperature of the ferroelectric thin-film is less than or equal to the predetermined temperature, the method comprising the steps of: preparing the substrate that satisfies the following formula (2) based on the thermal expansion coefficient of the ferroelectric thin-film when the ferroelectric thin-film satisfies the following formula (1); preparing the substrate that satisfies the following formula (4) based on the thermal expansion coefficient of the ferroelectric thin-film when the ferroelectric thin-film satisfies the following formula (3); preparing the substrate that satisfies the following formula (6) based on the thermal expansion coefficient of the ferroelectric thin-film when the ferroelectric thin-film satisfies the following formula (5); and depositing the ferroelectric thin-film on the substrate at a temperature higher than or equal to the predetermined temperature, wherein the formulas (1) through (6) are 1.0<( c/a ) film ≦1.015 (1), α film −α sub (° C. −1 ) film ≧3.0×10 −6 (2), 1.015<( c/a ) film ≦1.045 (3), α film −α sub (° C. −1 )≧9.0×10 −6 (4), 1.045<( c/a ) film ≦1.065 (5), α film −α sub (° C. −1 )≧12.0×10 −6 (6), where (c/a) film is the lattice constant ratio of the crystal axes of the ferroelectric thin-film, α sub is the thermal expansion coefficient of the substrate, and α film is the thermal expansion coefficient of the ferroelectric thin-film in formulas (1) through (6).