Improvement of HfOx-Based RRAM Device Variation by Inserting ALD TiN Buffer Layer

Abstract

In this letter, the impacts introduced by oxygen-scavenging metal (Ti), including forming voltages variation and resistances dispersion in high/low states of HfO x -based RRAM devices, were investigated. Based on experiments, it is concluded that Ti atoms during physical vapor deposition process can randomly penetrate into the bulk of HfO x and are intended to randomly create the initial oxygen vacancies, thus causing the performance degradation. Moreover, a novel structure with an atomic layer deposition-TiN buffer layer inserted between oxygen-scavenging Ti and HfO x layers was proposed and experimentally demonstrated to reduce the impacts of Ti penetration, which further improves vacancy-creating approach. It was experimentally verified that with the help of incorporating a TiN buffer layer, the uniformity of switching parameters, such as forming voltage and resistance, was effectively improved. The understanding and improvement of device variation caused by oxygen-scavenging metal in oxides-based resistive random access memory (RRAM) are useful for further development of highly reliable RRAM technology.