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

In this letter, the impacts introduced by oxygen-scavenging metal (Ti), including forming voltages variation and resistances dispersion in high/low states of HfOx-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 HfOx 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 HfOx 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.