Radiation Tolerant Memory Device Materials

Radiation hardened ferroelectric random access memory (FRAM) devices have potential uses in numerous military applications. Until recently, FRAMs have relied on lead zirconate titanate (PZT) as the storage material. However, a new class of materials promises to offer higher device reliability and easier integration into existing technologies. SrBi2Ta209 has been identified as a material of choice for this application, but current deposition technologies require high temperature post-anneals to bring about acceptable ferroelectric properties. Phase I will develop new MOCVD techniques to deposit SrBi2Ta209 at reduced temperatures. Metalorganic chemical vapor deposition (MOCVD) represents an optimum solution because it yields microcrystalline material of high quality, has high deposition rates, produces conformal coatings, and scales well to large areas. SrBi2Ta209 FRAMs have immediate military application for high radiation environments such as missile guidance systems and space systems. For the commercial market, the initial introduction at low device densities would impact existing EEPROM markets and new markets in identification tags for consumer goods. High density devices used in telecommunications will follow.