Sunday, July 13, 2014

Ferroelectric deep trench capacitors based on Al:HfO2 for 3D nonvolatile memory applications

P. Polakowski, S. Riedel, W. Weinreich, M. Rudolf, J. Sundqvist, K. Seidel, J. Muller
Memory Workshop (IMW), 2014 IEEE 6th International
Date of Conference: 18-21 May 2014 Page(s): 1 - 4 Print ISBN: 978-1-4799-3594-9 Conference Location : Taipei, Taiwan DOI:10.1109/IMW.2014.6849367
Aiming for future nonvolatile memory applications the fabrication and electrical characterization of 3-dimensional trench capacitors based on ferroelectric HfO2 is reported. It will be shown that the ferroelectric properties of Al-doped HfO2 ultrathin films are preserved when integrated into 3-dimensional geometries. The Al:HfO2 thin films were deposited by ALD and electrical data were collected on trench capacitor arrays with a trench count up to 100k. Stable ferroelectric switching behavior was observed for all trench arrays fabricated and only minimal remanent polarization loss with increasing 3-dimensional area gain was observed. In addition these arrays were found to withstand 2∗109 endurance cycles at saturated hysteresis loops. With these report the 3D capability of ferroelectric HfO2 is confirmed and for the first time a feasible solution for the vertical integration of ferroelectric 1T/1C as well as 1T memories is presented.

Process flow scheme for the fabricated ferroelectric deep trench capacitors with high aspect ratio of 13:1 and the accordingly measured hysteresis loop of a 3D deep trench capacitor