Analysis by simulation of amorphization current in phase change memory applied to pillar and GST confined type cells

In this work comparative simulations and analysis of amorphization current are presented for pillar type and GST confined type PCRAM structures. The simulations are realized with the PCM model of Sentaurus Device using an analytical phase transition model coupled with a drift-diffusion electro-thermal model for the transport. The objectives of this work are the selection of optimized cell structures for reset conditions. It is confirmed that regarding Ireset the GST confined cell is more efficient than the pillar type. Our study points out that a compromise has to be found in some devices where the conditions of an optimized amorphous current correspond to a lowered resistivity contrast between the amorphous and crystalline states. A compromise has also to be found between optimal structures as designed by simulation and technological constraints associated to their fabrication.