METHOD FOR MANUFACTURING FERROELECTRIC MEMORY DEVICE HAVING BLT FERROELECTRIC FILM

摘要

PURPOSE: A fabrication method of ferroelectric memory devices having a BLT film is provided to improve electrical properties of a ferroelectric capacitor and to decrease crystallization temperature of the BLT film. CONSTITUTION: A lower electrode(40) is formed on a semiconductor substrate(30) having a transistor so as to connect a plug(39). A BLT ferroelectric film(41) of (BixLay)Ti3O5 is then formed on the lower electrode(40), wherein the atomic concentration(x) of Bi in the (BixLay)Ti3O5 ferroelectric film(41) is 3.25-3.35 and the atomic concentration(y) of La is 0.70-0.90. The (BixLay)Ti3O5 ferroelectric film(41) is firstly annealed for nucleation at the temperature of 400-800°C, and secondly annealed for crystallization at the relatively low temperature of 500-675°C. An upper electrode(42) is formed on the (BixLay)Ti3O5 ferroelectric film(41).