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|High Temperature Characterization up to 450 °C of MOSFETs and Basic Circuits Realized in a Silicon-on-Insulator (SOI) CMOS-Technology|
|Keywords: High temperature, SOI, CMOS|
|Standard Bulk-CMOS-technology targets use-temperatures of not more than 175 degC. Silicon-on-Insulator-technologies are currently used up to 250 degC. In this work, we evaluate the limit for electronic circuit function realized in thin film SOI-technologies for even higher temperatures. At Fraunhofer IMS, a versatile 1.0 µm SOI-CMOS process based on 200 mm wafers is in production. It features three layers of tungsten metallization with excellent reliability concerning electromigration, voltage independent capacitors, high resistance resistors, and single-poly-EEPROM cells. In this paper, we present a study of the temperature dependence of MOSFETs and basic circuits, produced in the process described before. The electrical characteristics of NMOSFET- and PMOSFET-transistors were studied up to 450 degC. In a second step, we investigated the functionality of ring oscillators, representing digital circuits, and bandgap references as examples of simple analog components. The frequency and the current consumption of ring oscillators and the output voltage of bandgap references were characterized for temperatures up to 450 degC. We found that the ring oscillator still functions at this high temperature with a frequency of about one third of the value at room temperature. The output voltage of the bandgap reference is in the specified range up to 250 degC, and shows reduced performance in the extended temperature range up to 450 degC. The acquired data provide an important foundation to extend the application of CMOS-technology to its real maximum temperature limits.|
|Katharina Grella, Research Fellow / Ph.D Student
Fraunhofer Institute for Microelectronic Circuits and Systems IMS