Semiconductor integrated circuit device with information storage capacitor having ruthenium dioxide lower electrode and crystallized TA2O5 capacitor insulator

A semiconductor integrated circuit device including a memory cell comprising a memory cell selecting MISFET Qs formed on the main surface of a semiconductor substrate 1 and an information storage capacitor C that is connected in series to said memory cell selecting MISFET Qs, and that have a lower electrode 54, a capacitor insulator 58 and an upper electrode 59, wherein the lower electrode 54 is made of a conductive material containing ruthenium dioxide (RuO2) as principle ingredient and the capacitor insulator 58 is made of crystalline tantalum pentoxide. Thus, the capacitance required for the memory cells of a 256 Mbits DRAM or those of a DRAM of a later generation can be secured.