ALD Encapsulation for Silver Mirror Protection in Optoelectronic Chips
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Solution Overview
Problem
Optoelectronic semiconductor chips, particularly those with silver mirror layers, face issues with diffusion, electromigration, and oxidation, leading to reduced reflectivity and efficiency, especially in humid environments, and existing metallic encapsulations can absorb radiation, further reducing performance.
Innovation Solution
The use of Atomic Layer Deposition (ALD) encapsulation layers, which are thin, radiation-transmissive, and electrically insulating, effectively protects the mirror layers from moisture and gases, while allowing the mirror layers to be positioned closer to the surface for increased reflectivity and efficiency, and additional encapsulation layers are used to prevent material diffusion and absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a metallic mirror layer (silver or aluminum) is used to reflect electromagnetic radiation, then reflectivity is improved, but the mirror layer is prone to diffusion, electromigration, and oxidation which reduces reflectivity and efficiency over time
Solution Approach 1:
A diffusion barrier layer is introduced as an intermediary between the metallic mirror layer and the surrounding environment. This barrier layer prevents direct contact between the metal and oxidizing agents or diffusing species, thereby maintaining the mirror layer's reflectivity and preventing degradation from oxidation and electromigration while preserving the high reflectivity function.
Solution Approach 2:
The mirror structure is transformed from a single metallic layer into a composite structure consisting of multiple layers including the metallic mirror layer and protective diffusion barrier layers. This composite construction combines the high reflectivity of metals with the protective properties of barrier materials, achieving both high illumination intensity and long-term reliability.
2Reliability
If metallic encapsulation layers are used to protect mirror layers, then protection from moisture and oxidation is improved, but radiation absorption increases which reduces efficiency
Solution Approach 1:
Thin film encapsulation layers are used to protect the mirror layer. These thin films provide adequate protection against moisture and oxidation while being sufficiently thin to allow most electromagnetic radiation to pass through, thus minimizing energy loss from absorption while maintaining reliability.
Solution Approach 2:
The thickness and material properties of the encapsulation layers are optimized to achieve the right balance between protection and transparency. By carefully controlling the thickness parameter and selecting materials with appropriate optical properties, the encapsulation provides effective moisture barrier protection while maintaining high radiation transmission to minimize energy loss.
3Productivity
If the mirror layer is positioned closer to the surface, then reflectivity and efficiency are improved, but protection from environmental factors is reduced
Solution Approach 1:
The diffusion barrier layer serves as an intermediary protective structure that allows the mirror layer to be positioned closer to the surface for improved efficiency while still providing protection from environmental factors. The barrier layer mediates between the need for high efficiency (close positioning) and protection needs, enabling both objectives to be achieved simultaneously.
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 ALD encapsulation layers enhance the durability and efficiency of the optoelectronic semiconductor chip by preventing moisture and gas penetration, reducing absorption of electromagnetic radiation, and improving low current performance, allowing for efficient generation of electromagnetic radiation even at low current intensities.
Implementation Method 1
The at least three encapsulation layers are provided to stop diffusion of material from the first mirror layer into other regions of the optoelectronic semiconductor chip and/or to impede or prevent penetration of atmospheric gases and/or moisture to the first mirror layer
Implementation Method 2
the first mirror layer is provided to reflect the electromagnetic radiation generated in the active region. The electromagnetic radiation impinges in part on the first mirror layer and is reflected thereby towards the outer face of the semiconductor body
Implementation Method 3
The use of Atomic Layer Deposition (ALD) encapsulation layers, which are thin, radiation-transmissive, and electrically insulating
Data Source
AI summary
An optoelectronic semi-conductor chip is disclosed in which an encapsulation layer, which is an ALD layer, completely covers a first mirror layer on the side thereof facing away from a p-conductive region, and is arranged to be in direct contact with said first mirror layer in some sections.