High-Density Integration

Abstract

Ferroelectric random access memory (FeRAM) has been pursued as a promising new memory due to its ideal memory properties, such as fast random access in read/write mode and nonvolatility with unlimited usage. However, FeRAM has only achieved limited success in low-density applications because of its large cell size (large cell size factor). Recently, mega-bit density scaled FeRAMs have been developed with many key process and new integration technologies. Among those technologies, 1T-1C COB (capacitor over bit line) cell structure is the most important, because it can greatly reduce the cell size of FeRAM. With these technologies, 0.25 micro meter 32 Mb FeRAM with the 15 F\(^2\) cell size factor of a 1T-1C COB cell has been successfully developed. In order to further reduce the cell size factor to its theoretical limits of 6 F\(^{2}\) or 8 F\(^{2}\), it is highly desirable to develop three-dimensional ferroelectric capacitor technology, where CVD technology is essential for fabricating ferroelectrics as well as electrodes.Keywords77.84.B68.55.JKeywords77.84.B68.55.J