Extended switching endurance of phase change memory through nano-confined cell structure

Abstract

Phase change memory has been regarded as a promising candidate for storage class memory application. However, the high switching current and limited switching endurance remain a critical challenge. In this work a switching endurance beyond 1.1 × 1011 cycles is demonstrated in the mushroom-type memory device with nano-cofined structure and carbon-doped GeSbTe material. The over-programming of the memory cell induced by excessive RESET current gives rise to the recrystallization of the active phase change volume which accelerates the inward migration of carbon atoms to the bottom heater. The cyclic switching exacerbates the over-programming effect with denser carbon cluster accumulated at the boundary of the active region which causes the stuck-RESET failure. The nano-confined cell structure enables efficient heating by relocating the melt-quench region away from the interface to the dielectric layer which substantially reduces the RESET energy and, consequently, mitigates the over-programming effect and significantly extends the switching cycles. Extending the endurance of mushroom-type phase change memory remains challenging. Here, the authors design a nano-confined cell with an embedded heater, achieving a 1000 × improvement and attributing failure to carbon-induced collapse of the switching volume.