LED Chip Electrode Extensions and Gradient Vias for Uniform Current Spreading
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Solution Overview
Problem
Conventional LED technology faces challenges in maximizing light emission efficiency and current spreading, particularly for larger area LEDs, leading to non-uniform current distribution and reduced recombination efficiency.
Innovation Solution
The introduction of LED chip structures with electrode extensions and gradient via arrangements, featuring variable diameters, pitches, and widths, which are designed to optimize current injection and recombination efficiency across the LED chip area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electrode structures are used in larger area LEDs, then manufacturing is simpler, but current spreading is insufficient and recombination efficiency is reduced
Solution Approach 1:
The patent applies local quality by implementing gradient vias with varying diameters and pitches in different regions of the LED chip. The via diameter and pitch are optimized locally based on the current density distribution requirements, with smaller diameters and tighter pitches near electrode pads for better current injection, and larger diameters and wider pitches toward the center for improved current spreading. This localized optimization resolves the contradiction by enhancing recombination efficiency through region-specific structural adjustments without requiring complete redesign of the entire electrode system.
Solution Approach 2:
The patent employs parameter changes by systematically varying via diameter, via pitch, and electrode extension width as continuous gradients across the LED chip area. These parameters are not uniform but change progressively from the electrode pad regions toward the center, creating optimized current distribution pathways. This approach improves recombination efficiency by adapting structural parameters to local current density requirements while maintaining a systematic design that avoids excessive complexity.
2Reliability
If uniform via arrangements are used, then manufacturing is easier, but current distribution becomes non-uniform and localized heating increases
Solution Approach 1:
The patent implements local quality through gradient via arrangements where via diameter and pitch vary according to position on the chip. Regions closer to electrode pads feature smaller via diameters and tighter pitches to concentrate current injection, while regions toward the center have larger diameters and wider pitches to distribute current evenly. This localized variation ensures uniform current distribution across different chip areas, preventing localized heating while maintaining manufacturability through systematic gradient patterns.
Solution Approach 2:
The gradient via arrangement aims to create equipotential conditions across the LED chip by compensating for natural current density variations. By adjusting via dimensions and spacing, the structure balances the electrical potential distribution, ensuring that current flows uniformly through the active region. This approach addresses non-uniform current distribution and reduces localized heating while using systematic variations that remain manufacturable.
3Productivity
If larger electrode surface areas are used, then current spreading improves, but light extraction efficiency is reduced due to increased absorption
Solution Approach 1:
The patent applies local quality by using variable width electrode extensions that are wider near the electrode pads for effective current collection and connection, and progressively narrower toward the center of the chip. This gradual width reduction minimizes the total electrode surface area in regions where light extraction is critical, thereby reducing light absorption losses. Meanwhile, the narrower extensions still provide sufficient current spreading pathways, resolving the contradiction between current spreading effectiveness and light extraction efficiency.
Solution Approach 2:
The patent transitions from two-dimensional uniform electrode structures to three-dimensional gradient structures by varying via diameters and electrode extension widths in the vertical dimension relative to the chip surface. This dimensional approach allows optimized current distribution through vertical gradient profiles while reducing the lateral footprint of electrodes in light extraction zones, thereby minimizing light absorption without compromising current spreading capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances uniformity in carrier distribution, improves recombination efficiency, and increases overall emission efficiency by addressing non-uniform current distribution and reducing localized heating.
Implementation Method 1
diameters of individual vias of the plurality of vias vary with distance from the first electrode pad... improves recombination efficiency, and increases overall emission efficiency by addressing non-uniform current distribution
Implementation Method 2
When a bias is applied across the doped layers, holes and electrons are injected into the one or more active layers where they recombine to generate emissions such as visible light or ultraviolet emissions
Data Source
AI summary
Solid-state lighting devices including light-emitting diode (LED) chips and more particularly LED chip structures with electrode extensions and gradient via arrangements are disclosed. Electrode extensions and vias are formed on opposing sides of an active LED structure as part of anode and cathode connections. Gradient via arrangements include variable diameter and/or variable via pitch relative to electrode extensions and electrode pads. Additional structures include variable width electrode extensions relative to vias and/or electrode pads. Layouts of gradient vias and corresponding electrode extensions are disclosed for increasing uniformity in recombination efficiency across LED chip areas and for providing improvements to current injection, current droop, and overall emission efficiency.