METHOD OF MAKING SEMICONDUCTOR FERROELECTRIC MEMORY ELEMENT AND SEMICONDUCTOR FERROELECTRIC MEMORY TRANSISTOR

Described is a FeFET and a method of its manufacture, the FeFET having a ferroelectric whose film thickness (dr) is in the range: 59 nm < dr < 150, without impairing the data retention property of not less than 10 5 seconds and the data rewrite withstand property of not less than 10 8 times, and the FeFET allowing data to be written with a writing voltage whose absolute value is not more than 3.3 volts. The method comprises sequentially forming in the indicated order on a semiconductor substrate an insulator, a bismuth layered perovskite crystalline ferroelectric film and a metal. The stack is annealed for ferroelectric crystallization. Preferably, the film is composed of Ca. Sr, Bi, Ta and oxygen atoms, the metal is Ir or Pt or an alloy of Ir and Pt, or Ru, and the annealing is performed in a mixed gas having oxygen added to nitrogen or a mixed gas having oxygen added to argon.