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


A. Lamperti, Laboratorio MDM, IMM-CNR, Via Olivetti 2, 20864 Agrate Brianza MB, Italy.



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.