The Defense Advanced Research Projects Agency (DARPA) is soliciting innovative proposals for the research and development of thin-film heat spreader technology.Current heat spreader solutions use high thermal conductivity (TC) materials like copper (TC: 400 W/m·K) and aluminum nitride (TC: 320 W/m·K). However, these solutions lack the complete set of properties needed to make them both effective at heat spreading and survivable in extreme environments. The ultimate thin-film heat spreader must: 1) have high thermal conductivity and low thermal boundary resistance; 2) be integrable with a range of microsystem technologies with low deposition temperature; 3) be electrically insulating; and 4) be scalable, supporting formation on substrates ranging from small dies to full wafers. For this Small Business Innovation Research (SBIR) opportunity, specific targets of interest for demonstrating heat spreader approaches are high power semiconductor lasers and extreme temperature electronics.High power density systems like semiconductor lasers are employed across a broad range of industries, including communications, manufacturing, medical diagnostics and treatment, and national security. However, high-power lasers based on III-V semiconductor materials face significant thermal management challenges, largely due to the inherently low thermal conductivity of these materials. To address this, integrating effective heat spreaders near the active region is critical to enhancing device performance, thus improving wavelength stability, boosting laser efficiency and reliability, and mitigating thermal-induced distortions.The importance of heat spreaders also extends to electronic systems and sensors operating in extreme thermal environments (exceeding 800°C). At high temperatures, phonon scattering reduces heat conductivity and reduces the effectiveness of heat spreaders. Such conditions are encountered in oil and gas exploration, geothermal technologies, combustion engines, and military systems. In the absence of efficient thermal energy dissipation, localized temperatures can rise by over 200°C above ambient, resulting in peak device temperatures approaching 1000°C—levels that can severely degrade performance, compromise structural integrity, and shorten device lifespan.For this SBIR, proposals that develop heat spreader technologies that accommodate both high power density microsystems and extreme temperature microsystems are encouraged. Laminate film stacks are acceptable. Approaches that require active cooling are discouraged. Additionally, the heat spreader technology should have the following characteristics: • Uniform and conformal heat spreader thickness from 100 nm to 5 µm• Less than 450°C deposition temperature for compatibility with a broad spectrum of microsystems • Scalability from dies to full substrates • Thermal conductivity > 1500 W/m·K • Thermal boundary resistance < 5 m2K/GW between heat spreader and substrate material • Low surface roughness with < 10 nm root-mean-square (RMS) value• High electrical resistance• Low residual film stress that induces no warpage in the substrate• Survivability and high performance to 800°C and beyond (laser devices with proposed heat spreader are not required to meet this threshold)
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