Investigation of ultrathin Pt/ZrO2-Al2O3-ZrO2/TiN DRAM capacitors Schottky barrier height by internal photoemission spectroscopy

Abstract

We report the Schottky barrier height (SBH) at metal-insulator interfaces in Pt/ZrO2-Al2O3-ZrO2(ZAZ)/TiN dynamic random access memory capacitors by analyzing the photoconductivity yield and internal photoemission (IPE) yield using IPE spectroscopy. The SBH values at the Pt/ZAZ and ZAZ/TiN interfaces in the Pt/ZAZ/TiN stack were found to be 2.77 and 2.18 eV, respectively. The SBH difference between the top electrode/oxide and bottom electrode/oxide interfaces is related to the work function difference between Pt and TiN, and the subgap defect state features (density and energy) of the given dielectric. By combining experimental analysis using IPE at the device level and ultraviolet photoelectron spectroscopy and spectroscopic ellipsometry at the film level, a band structure model is proposed. (C) 2016 Elsevier B.V. All rights reserved.