Resistive and synaptic properties modulation by electroforming polarity in CMOS-compatible Cu/HfO2/Si device

In this article, a complementary metal-oxide-semiconductor (CMOS)-compatible Cu/HfO2/Si synaptic device is proposed for neuromorphic systems in consideration of the forming polarity. To test this device, its chemical and material compositions are first verified by X-ray photoelectron spectroscopy (XPS). The bipolar resistive switching by a positive forming process is classified by the conventional conductive bridge random-access memory (CBRAM). Here, abrupt set and reset processes following filamentary switching are observed with a wide range of compliance current (CC) conditions. On the other hand, the bipolar switching with gradual set and reset processes by a negative forming process follows the interface type. The resistive switching of the interface mode occurs as a result of the distribution of oxygen vacancies. The interface type shows more linear potentiation and depression curves than the filamentary mode, and the neuromorphic simulation results verify higher pattern recognition accuracy in interface type. Finally, it is verified that the target conductance can be easily reached by adjusting the amplitude and width of the pulse.