Development of Reflow Fill of CGeSbTe Films for Sub‐20 nm Cells in 3D Cross‐Point Memory

Abstract To obtain reliable and scalable cells in 3D cross‐point memory, endurance failures caused by voiding from etching damage to memory cells should be resolved to preserve the properties of GeSbTe (GST) phase‐change materials. Herein, the fabrication of a damascene cell without patterning, which relies on the bottom‐up fill of carbon‐doped GST layers into confined cells, is proposed as a promising solution. The reflow fill of the sputtered carbon‐doped GST films into confined cells at high‐temperature and low‐power conditions is demonstrated, and a mechanism in which Sb and Te transfer into the cell through vapor transfer and viscous flow due to capillary pressure is verified. The aspect ratio increases from 2 to 7.7 under enhanced vaporization of Sb and Te as well as the capillary force. The advanced reflow‐fill process using a laser can overcome the limit of the conventional reflow‐fill technology by increasing the atomic mobility above the melting temperature. Based on the proposed method, 19 nm cross‐point memory devices are successfully integrated together with the Ovonyx threshold switch and appropriate memory windows are secured. Furthermore, the 9 nm cells exhibit reliable endurance cycles over 10⁸.