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

High dielectric constant (high-?) 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-? 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-?/SiO2/Si, integrating HfO 2, ZrO2, or DyScOx as charge-trapping layer or high-?/SixNy/SiO2/Si integrating DyScOx as control (blocking) oxide. The high-? 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. Copyright © 2012 John Wiley & Sons, Ltd.