Influence of Substrate on Hafnium Silicate Metal-Insulator-Metal Capacitors Grown by Atomic Layer Deposition
In this work we investigate the growth of hafnium silicate films by plasma assisted atomic layer deposition on a metal electrode. The hafnium silicate film was deposited using Tetrakis(dimethylamino)hafnium (TDMAHf) and Tetrakis(dimethylamino)silane (TDMASi) precursors at 250oC with a remote oxygen plasma (300 W). From HR-TEM analysis and Raman spectroscopy it has been observed that the main crystalline phase is monoclinic HfO2. This crystallographic phase appears to be templated by the underlying titanium adhesion (10 nm) layer through the platinum electrode (200 nm).
The HR TEM analysis also reveals the presence of nanoparticles, located primarily towards the lower platinum metal layer. Based on electron energy loss spectroscopy (EELS) analysis the nanoparticles are consistent with silicon oxide inclusions, located at HfO2 grain boundaries. In addition, the presence of additional phases was detected; these included a super-cell structure within the bulk and an amorphous phase. No hysteresis was observed in the capacitance voltage measurements and the material was observed to exhibit a k value of ~18.
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