Thermal stability of high‐κ oxides on SiO2/Si or SixNy/SiO2/Si for charge‐trapping nonvolatile memories

Abstract

High dielectric constant (high‐κ) oxides are foreseen replacement materials in innovative metal–oxide–semiconductor devices and memory capacitors. In particular, when considering nonvolatile memories, the charge‐trapping concept appears to be a promising solution for flash‐type floating gate replacement. Among the high‐κ oxide properties to be considered, it is essential to study the compatibility towards the integration of these materials in a complementary metal–oxide–semiconductor process, in particular to control the stack integrity and any onset of diffusion phenomena upon thermal treatments at temperatures higher than 1000 °C. Here, we report on the results obtained from time‐of‐flight secondary ion mass spectrometry depth profiling of stacks on the basis of high‐κ/SiO2/Si, integrating HfO2, ZrO2, or DyScOx as charge‐trapping layer or high‐κ/SixNy/SiO2/Si integrating DyScOx as control (blocking) oxide. The high‐κ oxides are all grown by atomic layer deposition. We will discuss the role of the different substrate/oxide coupling in preserving the stack and propose the better combinations in terms of thermal stability. Copyright © 2012 John Wiley & Sons, Ltd.