Stacked Light Emitting Structure with Via Pillars for Light Extraction
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Solution Overview
Problem
Current light emitting devices face challenges in improving light efficiency and light extraction, particularly in micro LED displays where the stacking of light emitting parts and the need for efficient electrical coupling and light management are critical for enhanced performance.
Innovation Solution
A light emitting device design featuring a stacked configuration of light emitting parts with a passivation layer, via patterns, extended patterns, and pads for electrical coupling, along with a light shielding layer and transparent adhesion parts to optimize light extraction and efficiency, including semiconductor layers and conductive patterns for improved electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If light emitting parts are stacked vertically to improve device integration, then device complexity is reduced and productivity is improved, but light extraction efficiency deteriorates due to overlapping structures
Solution Approach 1:
The patent introduces via patterns that extend vertically through multiple stacked light emitting parts, creating a third-dimensional electrical connection path. This allows independent electrical access to each stacked LED layer without increasing lateral pad area, thereby maintaining light extraction efficiency while improving device integration.
Solution Approach 2:
The patent introduces a light shielding layer as an intermediary element positioned between stacked light emitting parts. This layer selectively blocks light from lower layers that would otherwise interfere with upper layer emission, improving light extraction efficiency of individual layers while maintaining the compact stacked structure.
2Area of stationary object
If pads are placed close together to reduce device area, then area of stationary object is reduced, but light extraction efficiency deteriorates due to insufficient separation distance
Solution Approach 1:
The patent moves electrical connections from a two-dimensional pad layout to a three-dimensional structure using via patterns that penetrate through light emitting parts. This allows pads to be positioned closer together laterally while maintaining sufficient optical separation, as electrical connections occur through the vertical dimension rather than requiring large lateral distances.
Solution Approach 2:
The patent segments the electrical connection path into multiple vertical sections using via patterns that pass through different light emitting parts. This segmentation allows independent control and optimization of each layer's electrical connection, enabling compact pad placement while maintaining light extraction efficiency through proper via positioning.
3Reliability
If via patterns pass through multiple light emitting parts to improve electrical coupling, then electrical conductivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent introduces a light shielding layer as an intermediary that also serves as an alignment reference for via patterns. This layer provides a stable structural platform that facilitates precise via formation through multiple stacked light emitting parts, reducing manufacturing precision requirements while maintaining reliable electrical coupling.
Solution Approach 2:
The light shielding layer is formed in advance before via patterns are created. This preliminary action establishes a stable structural foundation that guides subsequent via formation, making the manufacturing process more tolerant to variations and reducing the precision requirements for aligning vias through multiple light emitting parts.
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 design enhances light extraction efficiency and color reproducibility by increasing the separation distance between pads and improving light reflection, resulting in improved contrast and performance in micro LED displays.
Implementation Method 1
a light shielding layer covering a portion of the first light emitting part to define a light extraction surface
Implementation Method 2
a passivation layer surrounding outer sidewalls of the first, second, and third light emitting parts
Data Source
AI summary
A light emitting device including a substrate having a first region and a second region, a light emitting stack including vertically stacked semiconductor layers disposed on the first region of the substrate, at least one pillar disposed on the second region of the substrate and laterally spaced apart from the light emitting stack, and at least one electrode extending from the first region to the second region of the substrate and electrically connecting the light emitting stack to the at least one pillar, in which the at least one pillar is disposed on the at least one electrode, respectively.