Semiconductor Light Emitting Element Adhesion via Thin Metal Layer
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Solution Overview
Problem
The thermal process used in bonding a conductive substrate to semiconductor light emitting elements can cause delamination of the insulating layer from the semiconductor layer due to weak adhesion, leading to reduced luminous efficiency.
Innovation Solution
A semiconductor light emitting element design that includes a second metal layer with a thickness of 5.0 nm or less between the semiconductor layer and the insulating layer, enhancing adhesion while maintaining effective current control and light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an insulating layer is provided adjacent to the second conductivity side electrode on the second conductivity type semiconductor layer to control current flow, then current control capability is improved, but adhesion between the insulating layer and semiconductor layer deteriorates due to thermal expansion during bonding process
Solution Approach 1:
A second metal layer is introduced as an intermediary between the insulating layer and the semiconductor layer. This intermediate metal layer serves as a buffer that accommodates thermal expansion differences during the bonding process, preventing delamination while maintaining the insulating layer's current control function.
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers (semiconductor layer, second metal layer, insulating layer, first metal layer) with different material properties. This composite structure allows each layer to perform its specific function while collectively resolving the adhesion problem through proper material selection and layer configuration.
2Strength
If a second metal layer is provided between the semiconductor layer and the insulating layer to improve adhesion, then adhesion strength is improved, but light absorption increases reducing light output
Solution Approach 1:
The thickness of the second metal layer is optimized to be 5.0 nm or less. By controlling this critical parameter, the metal layer provides sufficient adhesion improvement while minimizing light absorption, thus resolving the contradiction between adhesion strength and light output.
3Strength
If the thickness of the second metal layer is increased to improve adhesion, then adhesion strength is improved, but light extraction efficiency deteriorates due to increased light absorption
Solution Approach 1:
The second metal layer thickness is precisely controlled at 5.0 nm or less to optimize the balance between adhesion strength and light extraction efficiency. This parameter optimization ensures that the metal layer provides adequate mechanical bonding without excessively absorbing light.
Solution Approach 2:
Instead of using a thick metal layer that would guarantee adhesion but block light, the patent applies a thin metal layer (5.0 nm or less) that provides sufficient adhesion improvement while having minimal impact on light extraction, representing a partial action that achieves the necessary minimum effect.
4Reliability
If thermal process is performed for bonding conductive substrate to achieve electrical connection, then electrical connectivity is improved, but delamination of insulating layer occurs due to thermal expansion
Solution Approach 1:
The second metal layer acts as a stress buffer between the insulating layer and semiconductor layer during thermal bonding processes. This intermediary layer accommodates thermal expansion differences, preventing delamination while allowing the bonding process to proceed for achieving electrical connectivity.
Solution Approach 2:
The second metal layer is pre-positioned between the insulating layer and semiconductor layer before the thermal bonding process. This prior cushioning structure prevents delamination from occurring during subsequent thermal expansion, protecting the structural integrity before the harmful thermal stress is applied.
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 adhesion between the insulating layer and the semiconductor layer, ensuring effective current flow and light output by reducing light absorption and enhancing light extraction efficiency.
Implementation Method 1
improve adhesion between the insulating layer and the semiconductor layer by providing the second metal layer
Implementation Method 2
an insulating layer which can control current flow
Implementation Method 3
semiconductor light emitting element
Implementation Method 4
diffuse and reflect the light from the semiconductor layer to improve light extraction efficiency
Data Source
Figure 1~2
Figure 3(a)~3(b)
Figure 4~5
AI summary
A semiconductor light emitting device in which adhesion between an insulating layer and a semiconductor layer is improved while maintaining the ability of the insulating layer to limit the direction of current flow. The semiconductor light emitting device of the present invention includes a semiconductor layer, a first electrode and a second electrode arranged to interpose the semiconductor layer therebetween, an insulating layer provided to the semiconductor layer at the same side as the second electrode and opposite to the first electrodes so as to surround the periphery of the second electrode, a first metal layer covering the second electrode and the insulating layer, and a second metal layer which has a thickness smaller than the thickness of the second electrode and is provided between the semiconductor layer and the insulating layer.