Light emitting diode module for surface mount technology and method of manufacturing the same

What is this patent about?

’912 is related to the field of semiconductor light-emitting diodes (LEDs), specifically focusing on flip-chip architectures designed to improve reliability and light extraction. The invention addresses technical challenges associated with leakage currents, static electricity discharge, and current crowding that often occur when reflective metal layers are placed in direct contact with semiconductor surfaces containing structural defects.

The underlying idea behind ’912 is the introduction of a defect blocking layer—a patterned insulating structure—interposed between the second semiconductor layer and the reflective electrode. By strategically masking portions of the semiconductor surface, the invention prevents the reflective metal from touching potential defect sites, thereby cutting off leakage paths. The key engineering insight is the use of a variable area ratio for the openings in this blocking layer, which allows for precise control over current injection across the device surface.

The claims of ’912 focus on a stacked LED structure featuring an insulation layer specifically shaped to expose only selective portions of the second semiconductor layer. A reflective layer is then deposited over this insulation, making electrical contact with the semiconductor exclusively through these defined openings. This configuration ensures that the reflective electrode is both an optical component and a current-injection tool that is physically separated from the majority of the semiconductor surface by the insulating barrier.

In practice, the invention utilizes a mesa structure where the active and second semiconductor layers are etched to reveal the underlying first semiconductor layer. The defect blocking layer is applied to the top of these mesas with a distribution of openings that varies spatially; for instance, the density of openings is higher in the center and lower near the edges. This gradient compensates for the natural tendency of current to crowd near the n-type contact, ensuring a uniform glow across the entire active region and preventing localized overheating.

This approach differentiates itself from prior art by moving away from continuous, direct-contact reflection layers that are prone to cracking and electrical failure. By using the defect blocking layer as a current-shaping mask, the design simultaneously improves the device's resistance to electrostatic discharge and enhances light extraction efficiency. The resulting module maintains high conductivity and optical reflectance while shielding the sensitive active layers from the metallic diffusion and stress-induced cracks typical of conventional flip-chip designs.