Low RESET Current Mushroom-Cell Phase-Change Memory Using Fiber-Textured Homostructure GeSbTe on Highly Oriented Seed Layer

Abstract

Herein, a low RESET current 1T1R mushroom-cell phase-change memory (PCM) device that uses fiber-textured homostructure GeSbTe (GST) grown on highly oriented TiTe2 seed layer is reported. The homostructure device outperformed the industry standard device, that uses doped polycrystalline GST, on most figures of merit. The homostructure devices are also benchmarked against superlattice (SL) PCM devices with 10 periods of 5/5 nm GST/Sb2Te3 grown on the TiTe2 seed layer, and are found to have same low RESET current. It is also observed by transmission electron microscopy that the alternating layers of GST/Sb2Te3 and TiTe2/Sb2Te3 in SL devices are intermixed in the switched region after the devices are cycled with RESET/SET pulses. Additionally, when the SL device is left in the SET state, the intermixed switched region crystallinity is textured and exhibits van der Waals gaps. The SL PCM devices require a precise layered structure that is hard to yield on a full wafer scale. In contrast, fiber-textured homostructure PCM cells reported here are easily manufacturable, while providing similarly low RESET current and low-resistance drift, which makes this device suitable for analog artificial intelligence computation.