Patent ID: 7423308
Filing Date: 2008-09-09
Classification: H01L

Abstract:
1. A ferroelectric memory device, comprising: a transistor formed on a semiconductor substrate; and a ferroelectric capacitor connected electrically to said transistor, said transistor and ferroelectric capacitor both being integrated on the same substrate and constituting said ferroelectric memory device, said ferroelectric capacitor comprising; a lower electrode; a ferroelectric film provided over said lower electrode and having a perovskite-type structure; and an upper electrode provided over said ferroelectric film, wherein said ferroelectric film includes a first ferroelectric film part having a first crystal system and formed at an interface between one of said lower electrode and said upper electrode and a second ferroelectric film part, said second ferroelectric film part having a second crystal system that is different from said first crystal system, said first crystal system being a rhombohedral system, said second crystal system being a tetragonal system, and said second ferroelectric film part being oriented in any of the <001> direction and the <111> direction.