Investigation on scalability of dual trench epitaxial diode for phase change memory

In this paper, the scalability of dual trench epitaxial diode as the selector for phase change memory (PCM) has been analyzed. The 4 F2 diode with active area of 0.002916 µm2 has been fabricated using the standard 40 nm complementary metal oxide semiconductor process. The ratio of disturbance current between neighboring bit-lines (BLs) to drive current remains at average 2.0%. By introducing boron implantation into the device substrate, the punch-through voltage between neighboring word-lines (WLs) is larger than 6 V. Moreover, owing to the optimized P region in PN junction, the 4 F2 diode showed an excellent drive current of 431 µA. Finally, the resistances of 4/6.5/10/30 F2 diode array have been investigated, the series resistances of the buried N+ layer exhibited decreasing influence on drive current with the diode size scaling down.