Vertical Micro-LED Fabrication via Sapphire Substrate Light Extraction

The patent inverts the conventional lateral micro-LED structure by adopting a vertical configuration where the current flows perpendicular to the substrate surface. This inversion allows the micro-LED to achieve smaller footprint dimensions while maintaining manufacturing feasibility through standard epitaxial growth processes on sapphire substrates.

The patent transitions from a two-dimensional lateral structure to a three-dimensional vertical structure. By utilizing the vertical dimension for current flow and light emission, the device achieves higher density integration and improved resolution without compromising manufacturing simplicity.

The patent extracts and eliminates the complex substrate transfer and thinning steps from the conventional vertical micro-LED fabrication process. By keeping the micro-LED structure on the original sapphire growth substrate, the patent removes the need for delicate transfer operations and substrate thinning, significantly simplifying the manufacturing process.

The sapphire substrate serves multiple functions simultaneously: it acts as the growth substrate for epitaxial formation, provides mechanical support, and enables direct light extraction. This self-service approach eliminates the need for separate transfer substrates and complex assembly steps.

The sapphire substrate is designed to serve multiple functions: as the epitaxial growth substrate, as the mechanical support structure, and as the light extraction medium. The patent forms both P-type and N-type electrodes directly on the vertical micro-LED structure while it remains on the sapphire substrate, enabling complete device functionality without transfer operations.

The patent converts the potential disadvantage of having a thick sapphire substrate into an advantage by utilizing it for direct light extraction. The substrate's thickness, which would normally require thinning in conventional approaches, becomes beneficial for mechanical strength and optical performance simultaneously.

The patent segments the heat dissipation pathways by providing multiple thermal conduction routes: through the sapphire substrate and through the electrode structures. The vertical configuration enables direct thermal coupling with the substrate, improving heat sinking efficiency compared to lateral structures.

The patent employs an asymmetric vertical structure where the heat dissipation path is optimized independently from the light emission path. The bottom surface of the sapphire substrate serves as the primary heat sinking interface, while the top surface enables efficient light extraction, creating asymmetric functional optimization.