IMPROVEMENT IN RELIABILITY OF 0.25 mu m 15F~2 FRAM USING NOVEL MOCVD PZT TECHNOLOGY

摘要

We report on the measurements of reliability of 0.25 mu m 15F~2 cell FRAM using novel MOCVD PZT technology. The MOCVD PZT capacitors were prepared using a pre-purging process and successfully integrated into the 32 Mb FRAM process with double EBL technology and optimal ILD/1MD scheme. After full integration, the 0.44 mu m~2 MOCVD PZT capacitors with a 2Pr value of 35 mu C/cm~2 at an applied voltage of 2.7 V show superior retention properties. The MOCVD PZT cells have large sensing windows of 420 mV at an operation voltage of 2.7 V. The sensing windows show only a slight decrease during 100 hours of baking at a temperature of 150 deg C, after which not a single cells is observed to fail. Therefore, it is clearly demonstrated that using the novel MOCVD PZT capacitors, high reliability of 0.25 mu m 15 F~2 cell FRAM can be achieved.