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Scalable, Wide Bandgap Integrated Circuit Technology for Wide Temperature, Harsh Environment Applications


OBJECTIVE: Develop technology that advances the performance, reliability, and manufacturability of wide bandgap integrated circuit technology for applications from 300 degrees C to 500 degrees C. DESCRIPTION: The very nature of fifth-generation stealth aircraft poses increased challenges when it comes to thermal management. Many of the complications that are due to thermal management issues affect electronics performance. The addition of electric actuation, as with the Joint Strike Fighter (JSF), adds further to the demands of electronic systems on the aircraft. Silicon carbide (SiC) power electronic devices (diodes and switches) are currently being used as part of the solution. SiC devices can operate at higher temperatures than their Si counterparts. This higher temperature rating leads to better reliability and makes heat extraction easier. Control circuitry, however, is still accomplished with Si-based electronics. Silicon-on-insulator (SOI) technology has been demonstrated as high as 300 degrees C; but a rating of 225 degrees C is common for commercial SOI components. Further increasing the temperature rating of control circuitry up to and past 300 degrees C would allow collocation of power switches and their control circuitry in much higher ambient temperatures than currently attempted. The collocation of power devices and integrated circuits would reduce wiring, shielding, and cooling system demands and complexity. High-temperature integrated circuits (ICs) are also essential to the development of distributed engine control and smart sensors for turbine engine health management. A logical candidate for a high-temperature IC material is the same SiC that is yielding success on the power device front. Progress has indeed been made in the development and demonstration of SiC integrated circuits. Integrated circuits based on 6H-SiC JFET technology have been shown to operate from -125 degrees C to 500 degrees C and demonstrated thousands of hours of continuous operation at 500 degrees C. However, these logic circuits based on normally-on 6H JFETs suffered from long propagation times of over a micro second. ICs based on 4H-SiC bipolar junction transistors have been demonstrated at 355 degrees C and have propagation delays around 10 nano seconds. SiC BJT circuits, however, are more difficult to fabricate and are very sensitive to process variations. Success has also been recorded for 4H-SiC n-MOSFET based ICs operating at over 400 degrees C. These results demonstrate that high-temperature ICs can be made out of SiC; however, much work needs to be done in order to bring this technology to the point where it has the reliability, complexity, and performance required for insertion into the above-mentioned wide-temperature aerospace applications. This research topic seeks technologies that improve the performance, scalability, and manufacturability of wide bandgap (in particular, SiC)-based ICs. These advances may be (but are not limited to): Innovative circuit designs that better utilize current device technology. Advances in the design and fabrication of the basic IC building blocks (transistors, diodes, resistors, etc.). Technology that enables faster, more efficient logic architecture (complimentary logic design, for example). Fabrication advances that would enable scalability to a level suitable for ASIC or FPGA design. While SiC remains the most likely solution the wide-temperature applications discussed here, solutions based on other technologies such as other wide bandgap materials and/or heterostructures are not excluded. PHASE I: Demonstrate the feasibility of the proposed technology through fabrication, testing, and modeling and simulation of the basic IC building blocks operating from -50 degrees C to 300 degrees C. Modeling and simulation of design solutions based on previously demonstrated device technology may also suffice to show feasibility. A realistic, physics based roadmap to 350 degrees C continuous operation must be shown. PHASE II: Further develop the proposed technology and use it to produce an operational amplifier or IC of similar complexity that demonstrates the performance and scalability of the phase I technology. The circuit should demonstrate suitable functionality at temperatures up to at least 350 degrees C. PHASE III: Packaging, testing, and qualifying of critical IC component with broad applications to wide temperature aerospace needs. REFERENCES: 1. Neudeck, P., Garverick, S., Spry, D., Chen, L-Y.; Heheim, G., Krasowski, M., and Mehregany, M.,"Extreme temperature 6H-SiC JFET integrated circuit technology,"Phys. Status Solidi A 206, No. 10, pp. 23292345, (2009). 2. Singh, S., and Cooper, J.,"Bipolar Integrated Circuits in 4H-SiC,"IEEE Trans. Electron Devices, Vol. 58, No. 4, pp. 1084-1090, April 2011. 3. Le-Huu, M., Schrey, F., Grieb, M., Schmitt, H., Hublein, V., Bauer, A., Ryssel, H., and Frey, L.,"NMOS Logic Circuits using 4H-SiC MOSFETs for High Temperature Applications,"Mat. Sci. Forum Vols. 645-648 (2010) pp. 1143-1146.
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