Nitrogen-Oxyanion-Doped HfO2 Resistive Random-Access Memory With Chemically Enhanced Forming

Abstract

The high forming voltage of resistive random-access memory (RRAM) is one of the key bottlenecks for its integration in advanced silicon technology nodes. Here a nitrogen-oxyanion-doped (N-doped) hafnium oxide (HfO2) RRAM with overall improvement on forming voltage, on/off ratio and endurance is demonstrated. The critical electric field of N-doped RRAM for forming is 40% less than that of undoped RRAM. Therefore, a thicker resistive switching layer (RSL) can be used to obtain the same forming voltage, which benefits the on/off ratio and endurance performance. The N-doped RRAM achieves <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times $ </tex-math></inline-formula> improvement in on/off ratio and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10\times $ </tex-math></inline-formula> improvement in endurance at the forming voltage of 2 V, a value applicable for integration with advanced silicon technology node. We propose the hypothesis that the nitrites ((NO2)−) in the RSL of N-doped devices promote forming through introducing extra chemical process as well as additional conductive paths. Physical characterization and first-principles calculations are further carried out to validate our hypothesis.