Stacked Micro LED Structure for Red Luminance and Simpler Interconnects
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Solution Overview
Problem
Conventional micro LED displays face challenges in increasing red light luminance and simplifying the structure of stacked micro LEDs, which complicates electrical connections and manufacturing processes.
Innovation Solution
A light emitting device with a multilayer structure comprising multiple LED stacks and adhesive layers, where the first conductivity type semiconductor layer of one stack faces the second conductivity type semiconductor layer of another, and a distributed Bragg reflector enhances luminance and optical efficiency, while stress relief layers prevent warpage and cracking during bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If micro LEDs are arranged in pixel units on a plane to simplify mounting process, then mounting difficulty is reduced, but electrical connection structure becomes complicated
Solution Approach 1:
The patent transitions from planar arrangement to three-dimensional stacked arrangement of LED chips. Multiple LED chips are vertically stacked and electrically connected in series, converting the electrical connection problem from a two-dimensional plane to a three-dimensional structure, thereby simplifying the electrical connection structure while maintaining simplified mounting process
Solution Approach 2:
The patent combines multiple LED chips into a single stacked unit that functions as one integrated component. The stacked LEDs are electrically connected in series within the stack, merging multiple individual electrical connections into a unified structure that can be mounted as a single unit, thus simplifying both mounting and electrical connections
2Ease of manufacture
If multiple LED stacks are stacked vertically to reduce mounting difficulty, then mounting process is simplified, but manufacturing complexity increases
Solution Approach 1:
The patent divides the lighting system into multiple independent LED chip segments that are stacked vertically. Each LED chip is a separate functional unit with its own electrical connections, allowing independent manufacturing and assembly. This segmentation enables simplified mounting while the modular structure makes the overall manufacturing process more manageable despite the vertical stacking complexity
Solution Approach 2:
The patent implements a nested structure where multiple LED chips are stacked one inside another in a vertical configuration. The smaller LED chips are positioned within the vertical space occupied by the stack, creating a compact nested arrangement. This nesting approach reduces the horizontal footprint while maintaining the vertical stacking benefit for simplified mounting
3Illumination intensity
If red LED stacks are positioned at the upper portion to improve red light luminance, then red light output is enhanced, but optical path complexity increases
Solution Approach 1:
The patent applies local quality by positioning red LED chips specifically in the upper portion of the stacked structure where they can emit red light directly toward the viewing direction. This localized placement optimizes red light luminance for the specific functional requirement without requiring complex optical paths, as the red LEDs' natural emission direction aligns with the desired light output direction
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
The solution improves the luminance of red light and simplifies the structure of micro LED displays, enhancing manufacturing reliability and reducing optical distortion, thereby addressing the complexity of electrical connections and manufacturing challenges.
Implementation Method 1
a distributed Bragg reflector enhances luminance and optical efficiency
Implementation Method 2
first through third contact electrodes in ohmic contact with the second conductivity type semiconductor layers
Implementation Method 3
A light emitting device is a semiconductor device using a light emitting diode, which is an inorganic light source
Implementation Method 4
The light emitting diode has advantages of long lifespan, low power consumption, and fast response speed
Data Source
AI summary
A light emitting device according to an embodiment includes: a substrate; first through third LED stacks disposed on the substrate, and including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer, respectively; a lower insulation layer covering the first through third LED stacks; an upper insulation layer disposed on the lower insulation layer; and electrode pad layers disposed on the upper insulation layer, and electrically connected to the first through third LED stacks, in which the lower insulation layer has openings allowing electrical connection to the first through third LED stacks, the upper insulation layer covers the lower insulation layer such that each of the openings in the lower insulation layer is at least partially exposed, and the electrode pad layers extend on the upper insulation layer to pass through the openings in the lower insulation layer.