Semiconductor Light Emitting Device Adhesive Layer Openings
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Solution Overview
Problem
Semiconductor light emitting devices face inefficiencies in light extraction due to total internal reflection and heat generation, which reduce their lifespan and emission efficiency, particularly in flip-chip bonding structures where light is affected by refractive indices of layers.
Innovation Solution
A semiconductor light emitting device structure is developed with a conductive semiconductor layer, active layer, and insulating layers, including an adhesive layer with specific openings to enhance light reflection and extraction efficiency, and a method for manufacturing this structure that involves sequential layer formation and etching to optimize electrode placement and light path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective layer is provided on the rear surface of the substrate to discharge light toward the substrate, then light extraction efficiency is improved, but light generated in the active layer is affected by refractive index of each layer such that light fails to be totally extracted
Solution Approach 1:
The device is divided into multiple functional layers including a light emitting layer, a first insulating layer with first openings, and a second insulating layer with second openings. This segmentation allows light to be extracted through multiple pathways (substrate and side walls) rather than relying on a single reflective layer, thereby improving light extraction efficiency while maintaining manageable structural complexity through modular layer design.
Solution Approach 2:
Light extraction is extended from a single dimension (through the substrate via reflective layer) to multiple dimensions by adding side wall extraction paths through openings in the insulating layers. This multi-dimensional approach allows light to escape through both the bottom substrate and the lateral surfaces, improving overall extraction efficiency without requiring an overly complex single-structure solution.
2Loss of energy
If total internal reflection occurs on the interface between layers with different refractive indexes, then light is trapped inside the semiconductor layer, but heat is generated which decreases device life
Solution Approach 1:
The patent converts the harmful effect of total internal reflection (which traps light and generates heat) into a beneficial structure by introducing insulating layers with openings. These openings provide escape paths for light that would otherwise be trapped by refractive index differences, thereby reducing heat generation and improving device reliability while maintaining the necessary layer structure for light emission.
Solution Approach 2:
The insulating layers are designed with openings (porous structure) that allow light to pass through and escape from the semiconductor layer. This porous design addresses the total internal reflection problem by providing multiple exit points for light, reducing the amount of heat generated and thereby extending device life without compromising the structural integrity needed for light generation.
3Manufacturing precision
If the width of openings in the adhesive layer is smaller than the width of openings in the insulating layer, then electrode alignment is difficult, but manufacturing precision is reduced
Solution Approach 1:
The adhesive layer is formed with openings that are wider than or equal to the openings in the insulating layer below, creating a preliminary alignment guide structure. This preliminary action ensures that subsequent electrode formation can be easily aligned with the underlying structures, improving manufacturing precision without significantly increasing manufacturing difficulty, as the wider openings in the adhesive layer serve as built-in alignment references.
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 increases light extraction efficiency and adherence of electrodes, reducing heat generation and operational voltage, thereby enhancing the reliability and lifespan of the semiconductor light emitting device.
Implementation Method 1
an adhesive layer disposed between the electrode layer and the insulating layer. The adhesive layer includes a first opening and a second opening. The first opening of the adhesive layer overlaps the first opening of the insulating layer, and a width of the first opening of the adhesive layer is equal to or larger than a width of the first opening of the insulating layer
Implementation Method 2
One of the obstructive factors in discharging light to the outside of the semiconductor light emitting device is total internal reflection. Total internal reflection occurs on an interface between layers having different refractive indexes between respective layers of the semiconductor light emitting device
Data Source
AI summary
A semiconductor light emitting device includes a light emitting structure in which a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer are sequentially laminated, an insulating layer disposed on the light emitting structure and including first and second openings, an electrode layer disposed on the insulating layer and including first and second electrodes, and an adhesive layer disposed between the electrode layer and the insulating layer and including first and second openings. The first opening of the adhesive layer overlaps the first opening of the insulating layer and is equal to or larger than the first opening of the insulating layer. The second opening of the adhesive layer overlaps the second opening of the insulating layer and is equal to or larger than the second opening of the insulating layer.