A Non-Volatile SRAM For Spaceborne Applications Using a Novel Ferroelectric Non-Linear Dielectric, Phase I

A ferroelectric non-linear dielectric was recently discovered that, in their film form, possess a number of properties that make it an excellent choice for radiation-hardened electronics, particularly a radiation hardened (total dose hardened and SEE immune) non-volatile (NV) static random access memory (SRAM). Electrical measurements of these films demonstrated a relatively low dielectric constant (~20), an inherent ability to form a native buffer layer when deposited directly on silicon, and a strong polarization hysteresis effect. These results indicate that this film may be used to replace the two n-channel and two p-channel transistors in a traditional 4-T SRAM latch cell with two n-channel and two p-channel non-linear dielectric field effect transistors (NLDFETs). The threshold voltage hysteresis effect of the NLDFET should achieve full SEU immunity to at least 80MeV-cm2/mg of ionizing radiation, when used in a standard 6-transistor SRAM cell structure, thus have ultra-fast access times (like commercial SRAMs) while offering full non-volatility. In Phase I we will provide the device proof of concept, then in Phase II build a prototype memory. Phase III will see commercialization by licensing and sales. The resulting NV-SRAM products have the potential to be orders of magnitude faster than any existing EEPROM or FLASH devices because the nonlinear dielectric film forms a native dielectric with silicon giving the structure resistance to "wear-out" or "data-retention" problems. Finally, the SMI material is fully compatible with CMOS processing and has been accepted into major commercial silicon fabrication lines as a high-k dielectric for linear applications. More »