Contact Resistance Measurements of GST 225 to TiN Bottom Electrode

Abstract

The contact resistance between TiN and GST 225 was measured using the transfer length method (TLM) and the end resistance method for the crystalline and amorphous phases of GST 225. We found a 3000x increase in contact resistance when GST 225 over the TiN electrodes changed from crystalline to amorphous. When considering common phase change material (PCM) memory cell geometries, our measurements suggests that the contact resistance is a large component of the change in the resistance when the device is switched between the crystalline and the amorphous phases. In other words, the increase of the device resistance when the device is reset is substantially due to the increase in the contact resistance and not solely due the change in the bulk resistance of the PCM.