Researchers at NASA’s Glenn Research Center have developed a revolutionary new generation of silicon carbide (SiC) integrated circuit (IC) chips, setting an unprecedented benchmark in the field of high-temperature electronics. In the past, SiC ICs could not withstand more than a few hours of 500 °C temperatures before degrading or failing. Now, Glenn has successfully fabricated prototype chips that can exceed 10,000 hours of continuous operation at 500 °C. The advanced performance stems in part from the development of Glenn’s patented iridium interfacial stack (IrIS), a bondable metallization stack that prevents diffusion of oxygen and gold into silicon carbide (SiC) integrated circuits operating above 500 °C. The enhanced reliability of these components (and the transistors and logic boards they support) will enable important improvements in the control and operation of combustion engines, well-drilling, and other harsh environment systems, thereby greatly impacting operational efficiency and environmental quality. This advance in the manufacture of SiC-based electronics also fundamentally revolutionizes the opportunities for intelligent systems operating in high-temperature environments.
The IrIS acts as both a bond metal and a diffusion barrier within the IC chip. SiC integrated circuits designed for operation in air at 500 °C or above need this barrier to prevent gold or oxygen from diffusing to the ohmic contact interface that transports electrical signals into and out of the SiC semiconductor. These elements interfere with the performance of the interface once they diffuse in sufficient quantities. Because the IrIS also acts as a bond metal, the diffusion barrier bonds more easily for electrical connection to off-chip circuitry. Glenn’s patented innovation thus allows the bond metal to be used directly on ohmic contact metal, or on top of dielectric insulating layer(s) as an interconnect metal. In addition, the fabrication of the IrIS stack does not require extra anneals or masking steps, so the stack is both time-efficient and cost-effective to produce.
Additional technology from Glenn includes the fabrication of a self-aligned nitrogen-implant that works especially well with junction field effect transistors (JFETs), which are composed of silicon carbide. These JFETs are capable of being electrically operated continuously for 10,000 hours at 500 °C while undergoing less than 10 percent change in operational transistor parameters. Furthermore, the same methods have produced semiconductor devices for aerospace combustion applications that operate in temperatures up to 600 °C. This technology is a game-changer for high-temperature, harsh-environment applications of all types.
Potential applications include aerospace, oil and gas combustion (lower pollution and improved fuel economy), well drilling (deeper wells drilled faster for enhanced oil production), transportation (personal, commercial, military), and computers.