Degradation of Pt/PLZT/Pt capacitors caused by hydrogen in interlayer dielectrics

Abstract

A correlation between ferroelectric properties of the PLZT capacitors and amount of H2 and H2O gasses desorbed from interlayer dielectrics were investigated quantitatively. H2 and H2O gasses desorbed from interlayer dioxides were analyzed using thermal desorption spectroscopy. Polarization charges and its aging characteristics of memory array capacitors with area of 2 μm squares did not depend on amount of desorbed H2 explicitly, but strongly on H2O desorption. It is considered that silanol and hydroxyalkyl groups worked as hydrogen donor with catalytic activities of Pt top electrodes. As a result, hydrogen atoms should work as a major degradation agent for the imprint phenomena of memory array capacitors. Precise control of hydroxyl groups contained in the interlayer dielectrics and passivation films resulted in very small retention degradation caused by imprint phenomena, and realized high reliability and high density FRAM technologies.