Improved interface quality of atomic-layer-deposited ZrO2 metal-insulator-metal capacitors with Ru bottom electrodes

Abstract

We investigate effects of bottom electrodes on ZrO2 thin films formed through atomic layer deposition (ALD). We focus on the correlation between interfacial layer formation and electrical properties. For this comparative study, two different bottom electrodes consisting of TiN and Ru were employed. ALD ZrO2 films are deposited on these bottom electrodes by using tris(dimethylamino)cyclopentadielnyl zirconium ((C5H5)Zr[N(CH3)2]3) and ozone as a precursor and oxidant, respectively. Based on detailed investigations using transmission electron microscopy and X-ray photoelectron spectroscopy, we are able to comparatively characterize the formations and chemical compositions of the interfacial layers between ALD ZrO2 and both bottom electrodes. Based on the electrical properties of metal-insulator-metal capacitors fabricated using both the TiN and Ru bottom electrodes, we observe improved capacitance-voltage and current-voltage characteristics with the Ru bottom electrode, which are attributed to the suppressed formation of an interfacial layer. We also discuss the correlation between traps in the interfacial layer and electrical properties.