Failure Analysis and Performance Improvement of Phase Change Memory Based on Ge2Sb2Te5

As the operating conditions are getting harsher, the failure analysis of Phase Change Memory (PCM) are getting more and more important. In this work, some nonvolatile Phase Change Memory (PCM) devices based on Ge2Sb2Te5 are found RESET stuck failure during the pulsed mode switching. The causes, which result in the early failure of the PCM, have been studied by combining transmission electron microscopy (TEM), the two-dimensional finite analysis and energy dispersive X-ray spectroscopy (EDS). Compared with the typical devices, the incomplete crystallization in the inactive region of the abnormal devices are found based on the TEM images and corresponding fast Fourier transform (FFT) patterns, which is taken as the one of the major reasons for the SET failure confirmed by the simulation data. On the other hand, the element analysis was also carried out. Based on the EDS results, segregation of Te is considered to be another cause of the failure. To optimize performances of the RESET stuck devices, a DC initialization method is used. The resistance distributions of PCM cells before and after the DC initialization are presented, which shows a significant improvement in cells SET performance.