Optoelectronic Chip Encapsulation for Moisture Protection
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Solution Overview
Problem
Luminescence diode chips face degradation due to oxidation of the mirror layer and moisture sensitivity, which affects their aging stability and performance.
Innovation Solution
An optoelectronic semiconductor chip design featuring a semiconductor body with an active region between conduction type layers, where a silver or high-reflectivity connection layer is encapsulated by a metallic, multilayered encapsulation layer that prevents moisture and air penetration, and extends beyond the semiconductor body to protect the connection layer from environmental influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a mirror layer is arranged between the semiconductor body and carrier element to reflect radiation and increase emission power, then the radiation power emitted overall is improved, but the chip becomes sensitive to moisture and air penetration causing oxidation and degradation
Solution Approach 1:
The encapsulation structure is divided into multiple functional layers: a first encapsulation layer that directly covers the mirror layer and connection layers to provide moisture barrier protection, and a second encapsulation layer that covers the active region and extends laterally to provide mechanical protection and additional environmental isolation. This segmented approach allows each layer to specialize in specific protective functions while maintaining the mirror layer's optical performance.
Solution Approach 2:
The encapsulation layers serve as intermediary protective barriers between the sensitive mirror layer/connection layers and the external environment (moisture and air). These intermediary layers prevent direct contact between the vulnerable metallic layers and harmful environmental factors, thereby preventing oxidation and material migration while allowing the mirror layer to maintain its radiation reflecting function.
2Reliability
If the first connection layer is directly exposed to the surroundings to enable electrical connection, then electrical conductivity is improved, but material migration and oxidation occur reducing chip reliability
Solution Approach 1:
Thin film encapsulation layers are applied over the first connection layer and mirror layer to create a protective barrier. These thin films conformally cover the layered structure, providing effective protection against moisture penetration and material migration while maintaining the electrical functionality of the connection layer through controlled openings or conductive pathways.
Solution Approach 2:
The encapsulation structure employs composite material systems combining different protective layers with complementary properties - the first encapsulation layer provides chemical protection against oxidation, while the second encapsulation layer provides mechanical strength and additional environmental barrier, creating a composite protective system that addresses multiple degradation mechanisms simultaneously.
3Reliability
If the encapsulation layer is limited to covering only the connection layer, then manufacturing complexity is reduced, but moisture can penetrate into uncovered regions causing degradation
Solution Approach 1:
The encapsulation structure transitions from a two-dimensional planar coverage to a three-dimensional extended structure. The second encapsulation layer not only covers the top surface but also extends laterally beyond the semiconductor body edges, creating an overhanging protective shield that prevents moisture ingress from the sides and provides comprehensive environmental protection without requiring complex multi-component assemblies.
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 encapsulation layer enhances the chip's aging stability and reduces moisture sensitivity, preventing material migration and degradation, thus maintaining performance over time.
Implementation Method 1
The encapsulation layer is arranged between the first connection layer and the carrier. By means of the encapsulation layer, the first connection layer, which is preferably embodied as a mirror layer for the radiation to be generated or to be received in the active region, is decoupled from the surroundings. It can prevent air or moisture from penetrating into the first connection layer.
Implementation Method 2
Furthermore, the encapsulation layer can suppress migration of material of the first connection layer, for example silver.
Implementation Method 3
a mirror layer is arranged between a semiconductor body having an active region provided for generating radiation and a carrier element, said mirror layer being provided for reflecting radiation generated in the active region and thus for increasing the radiation power emitted overall
Data Source
AI summary
An optoelectronic semiconductor chip has a semiconductor body and a substrate on which the semiconductor body is disposed. The semiconductor body has an active region disposed between a first semiconductor layer of a first conductor type and a second semiconductor layer of a second conductor type. The first semiconductor layer is disposed on the side of the active region facing the substrate. The first semiconductor layer is electrically conductively connected to a first termination layer that is disposed between the substrate and the semiconductor body. An encapsulation layer is disposed between the first termination layer and the substrate and, in plan view of the semiconductor chip, projects at least in some regions over a side face which delimits the semiconductor body.