Excellent data retention characteristic of Te-based conductive-bridge RAM using semiconducting Te filament for storage class memory

Abstract

In this work, we explore the electrical properties and data retention of Te-based conductive-bridge random-access memory (CBRAM) of ZrxTe1−x/Al2O3/Pt cells. The virgin resistance and forming voltage are decreased with increasing Zr composition (0.5 ≦ x ≦ 0.7) and decreasing electrolyte thickness. The resistance of the conductive filament (CF) formed in the Te-CBRAM shows semiconducting behavior that is decreased with increasing temperature, whereas a Cu-based CBRAM shows metallic behavior. Furthermore, the conductance change of Te-based CBRAM, during the filament dissolution step, occurs with lower conductance units than those of Cu/Ag-based CBRAM. The most differentiable characteristics of both devices are the data retention. Te-based CBRAM shows better data stability at high temperature (150 °C) than Cu-based device. Accelerated tests (250, 270, and 300 °C) were performed to understand the data retention of the Te-CBRAM, yielding excellent retention characteristics (10 years at 177 °C) despite its relatively low activation energy (Ea, 1.07 eV) than Cu/Ag- based devices. We believe that the excellent retention properties of Te-based devices are more influenced by the wide effective CF size than by Ea.