A stand-alone 32 Kbit EEPROM for high-temperature applications

The world market for high-temperature electronics (> 125°C) is steadily increasing. The leading application sector for high-temperature technology still continues to be in equipment used for oil and gas well logging. Moreover electronic working up to 200 - 250°C is getting more and more important for the automotive and aerospace industries. Applications in these sectors include distributed engine control systems, electronic braking, exhaust sensors and transmission control. For a wide range of these and future high-temperature applications nonvolatile memories are indispensable. Therefore a standalone 32 Kbit EEPROM working up to 225°C has been developed at the IMS. The design is suitable to combine several 32 Kbit EEPROM chips to larger memory units up to 1 Mbit. Furthermore the programming voltage is generated on-chip. Thus no external programming voltage has to be provided. The 1.6 µm IMS high-temperature SIMOX (Separation by IMplanation of OXygen) process is used for fabrication. For high reliability at elevated temperatures a two level tungsten metallization is applied. To enable wire bonding on the pads an additional gold layer is deposited.