Ferroelectric Material and Device Reliability

T.D. Hadnagy
Ramtron International Corporation

The last few years has seen the introduction of ferroelectrics based memories. The materials of choice have been PZT and SBT (Y1). There has been extensive research done in the integration of these materials into standard CMOS processing. This work has revealed many challenges associated with the control of ferroelectrics properties. Included among these is the necessity of not degrading the ferroelectric device properties, the electroding system and maintaining the CMOS device performance. These issues have had a direct impact on the reliability of the final products produced with a particular process flow. In this tutorial I will review the current understanding of PZT with some information about the other materials contenders. In particular the materials properties will be reviewed as a function of processing conditions and deposition conditions. Materials attributes and how they tie into product reliability and ultimately system requirements will be reviewed. Details associated with the major failure modes of ferroelectric memories will be discussed as well as methods use to circumvent them. The impact of processing conditions as well as materials choices on reliability will be discussed. Process integration issues are currently at a high level of interest and a number of different solutions are being pursued to address the issues of materials degradation. These include but are not limited to change of electrode structure, capacitor encapsulation methods, as well as process integration changes. The delivery of products to customers and the implementation of quality control mechanisms often reveal low percentage failure mechanisms that are either materials or process related. Finally the current status of product performance to industry standard reliability tests and future directions will be evaluated with an eye on trends and possible markets.

Domokos Hadnagy

Dr. Domokos Hadnagy has over 20 years of experience in the semiconductor industry. He has been an engineer and manager in the areas of reliability, failure analysis, device physics, quality and materials development. He has degrees in engineering physics from Cornell University and physics and materials science M.S. and Ph.D. from the University of Utah. His experience includes Post Doctoral Fellow at the Department of Material Science at Cornell University, Manager of the Departments Reliability and FA at Honeywell, UTMC and Ramtron International. Most recently he has been responsible for materials development in the area of ferroelectric materials. Currently he is the VP of Quality and Reliability Assurance at Ramtron International.