Capacitor, semiconductor device comprising the same and method of fabricating thereof

摘要

The semiconductor device comprises: a memory cell transistor formed on a semiconductor substrate 10; insulation films 22, 30 covering the memory cell transistor; a buffer structure 40 formed on the insulation film; and a capacitor including a lower electrode 42 formed on the buffer structure 40 and electrically connected to the source/drain diffused layer 20; a capacitor dielectric film 44 formed on the lower electrode 42, and formed of a perovskite ferroelectric material having a smaller thermal expansion coefficient than that of the buffer structure 40 and having a crystal oriented substantially perpendicular to a surface of the lower electrode 42. The buffer structure for mitigating the influence of the stress from the substrate is formed below the lower electrode, whereby a polarization direction of the capacitor dielectric film can be made parallel with the direction of an applied electric field between the upper electrode and the lower electrode. Consequently, an intrinsic polarization of the ferroelectric film can be utilized.