Comparison of the evolution of internal bias field of doped hafnia ferroelectric capacitors for the field-cycling reliability

Abstract

The discovery of ferroelectricity in HfO2 thin films extends the range of research on next-generation electronic devices. However, for commercial applications, reliable ferroelectric switching characteristics under electric field cycling of HfO2 thin films must be secured. Despite recent reports of improved reliability under electric cycling of HfO2 with various dopants, a deep understanding of the experimental results is still needed. Our research has confirmed that finer domains and grains formed in thin films doped with Si than in those doped with Zr. This difference leads to a difference in the size of the domain and the number of domain walls, and a large number of domain walls function to suppress the diffusion of oxygen vacancies, which is known to significantly affect the stability of hafnia. This dependence was verified by the observation of relatively limited changes in the internal electric field of the Si-doped HfO2 films during the progression of cycling, using the first-order reversal curve method and various electrical measurements.