Addition of Ca and Sr in PLZT to improve fram® performance and reliability

Abstract

Although endurance frequently receives the most attention when considering the use of ferroelectrics in memory devices, we find that retention is actually the more important concern. In particular, ferroelectric materials are prone to imprinting which is a tendency to form a preferred state. Once a preferred state is formed, memory failure can occur when trying to set the ferroelectric in the non-preferred state. In order to improve the resistance to imprint, calcium and strontium dopants in PLZT have been studied. The calcium and strontium were varied using multiple sputtering targets along with ICP to determine the composition. These films were then characterized for orientation, switching and imprint.

Key Words:

• imprint
• ferroelectric
• reliability
• scaling