INTEGRATION PROCESSES AND PROPERTIES OF SEMICONDUCTIVE OXIDE MEMORY TRANSISTOR

Abstract

ABSTRACT The retention problem is a technical challenge for one-transistor (1T) ferroelectric memory devices. Three possible mechanisms are responsible for the poor retention of one-transistor ferroelectric memories: namely, leakage current deals with charges trapping within the gate oxide and ferroelectric film, floating gate effect, and the depolarization field. In order to overcome these problems, a novel ferroelectric transistor design using a semiconductive oxide film in place of the gate dielectric has been fabricated. There is no insulator and floating gate, and only the ferroelectric thin film deposited on a semiconductive oxide in the gate stack; therefore, there is a very low depolarization field. The highly oriented ferroelectric thin films have been selectively deposited on the device trench structure, which resulted in lower leakage current. The bottom gate of the ferroelectric capacitor is electrically connected to the silicon substrate through the semiconductive metal oxide resulting in the improvement of the memory retention characteristics.