Thin Film Batteries For Microelectronics

The development of thin film, solid state batteries for microelectronic applications is proposed. The batteries will be fabricated on ceramic substrates suitable for encapsulation in integration circuits using lead frame technology or as discrete components in multichip modules. The batteries are based on a secondary (rechargeable) lithium system that incorporates a high charge capacity oxide cathode and a carbon anode, both deposited by low temperature processes. The principal short term military application for the batteries would be memory protection for CMOS static random access memory (SRAM) in the event of primary power loss. The Phase I program will fabricate and characterize single cell batteries deposited on Si substrates. These batteries will provide O.1 mA-hr at a cell voltage >2V, which is sufficient to maintain 1 megabyte of low power SRAM for more than 24 hours. Battery materials and a multilayer hermetic coating have been chosen to meet military specifications on thermal and environmental stability of integrated circuit components. The Phase II effort would focus on the optimization of battery performance, maximizing both capability, and integrating multiple cells onto a single substrate to allow series and parallel battery configurations to achieve higher cell voltages or greater rate capabilities. ANTICIPATED BENEFITS: Many critical or portable data storage and miniaturized electronic devices will benefit from the availability of thin film batteries. Commercial applications of the proposed technology are many. Personal computers, portable communications, and portable data storage systems will all use thin film batteries either for memory backup or as a secondary power source.