Electrochemically Induced Stresses in Amorphous Tantalum Oxide Films

Abstract

Hydration processes were previously thought to be limited in amorphous tantalum oxide (ATO) capacitors. However, in-situ measurements show that hydration can produce substantial stresses in ATO. These measurements were also used to systematically investigate several important factors during hydration: the ATO thickness, electrolyte pH, annealing, and electrical field variations. Analysis of these data indicates that hydration in aqueous electrolytes is a diffusion limited process with diffusivities of 2-3 (10)-15 cm2/sec. Pulsed electric fields with different strengths were also applied to further elucidate stress contributions from different mechanisms. Heat treatments up to 400?C produce changes in the structure of the ATO that leads to significant variations in the electrochemical hydration behavior. © 2013 The Electrochemical Society.