Longer wavelength visible MicroLEDs (green, amber and red) fabricated in cubic GaN look set to deliver significant efficiency advantages over their conventional counterparts produced in the hexagonal crystalline form of the material, an issue that has been preventing take off for the Augmented and/or Virtual Reality (AR/VR) headset market for several years now. With this roadblock removed, the AR/VR display market is primed for explosive growth. Kubos Semiconductors has developed and is commercialising technology for producing these devices.
A critical enabler for the production of cubic GaN is the substrate on which the material is grown which comprises a thin layer of high quality, cubic silicon carbide (3c-SiC) epitaxy deposited on a standard silicon wafer. In common with all semiconductor manufacturing, maximising the diameter of wafer employed is desirable to optimise cost. No domestic source of these substrates currently exists and Kubos is forced to import them from overseas. This project is aimed at establishing an onshore supply chain capable of delivering these critical 3c-SiC on silicon substrates at a quality equivalent to that currently being imported. Innovative processes will be evaluated to improve both product quality and the efficiency and cost of manufacture and demonstrate the principle that this supply chain can be used as a foundation for scaling to high volume 200mm wafer diameter.
Led by Kubos Semiconductors which will qualify the substrates for its standard cubic GaN epitaxy and fabricate LEDs, Advanced Epi will develop suitable 3c-SiC epitaxy production processes, Wafer Technology will develop a chemo-mechanical polish (CMP) process to achieve sub-nm roughness and planarization on cubic SiC and Oxford Instruments will develop a plasma process to prepare the grown SiC surface prior to cubic GaN epitaxy. The project will include extensive materials and device characterisation and is targeting a 200mm diameter wafer capability.