Flip-Chip Semiconductor Light-Emitting Element Electrode Thickness
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Solution Overview
Problem
Existing semiconductor light-emitting elements for flip-chip mounting face challenges in achieving desired electrode thickness without excessive residual stress or manufacturing difficulties, while ensuring high light utilization and dust resistance.
Innovation Solution
The semiconductor light-emitting element features bump electrodes with an under-bump metal layer and a plated metal layer, where the plated metal layer has a thickness of 3 μm to 30 μm, and is made of high-reflectivity metals like Al or Ag, allowing for enhanced reflectivity and easy formation using electrolytic plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the electrode film thickness is increased to 1 μm or greater to provide dust resistance and gap, then dust resistance and mounting gap are improved, but residual stress in the film becomes too great when formed by sputtering
Solution Approach 1:
The patent changes the deposition method parameter from sputtering to vacuum evaporation, and optimizes the film thickness parameter to 1 μm or greater. This parameter change allows achieving dust resistance and mounting gap while avoiding the residual stress problem that occurs with sputtering at these thicknesses
Solution Approach 2:
The patent uses a thick film electrode structure that copies the functional requirements of thin film electrodes (electrical conductivity, reflectivity) while adding the capability to provide physical gap and dust resistance through increased thickness without the stress constraints of sputtering
2Object-affected harmful factors
If the electrode film thickness is increased to 1 μm or greater to provide dust resistance and gap, then dust resistance and mounting gap are improved, but manufacturing difficulties arise due to constraints of manufacturing time, material utilization, and equipment when formed by vacuum evaporation
Solution Approach 1:
The patent optimizes the film thickness parameter to a specific range (1 μm or greater) and changes the deposition method to vacuum evaporation with controlled parameters. This allows achieving dust resistance while maintaining manufacturing feasibility by balancing film thickness with deposition rate and process time
Solution Approach 2:
The patent applies partial vacuum evaporation to achieve the minimum necessary thickness for dust resistance (1 μm or greater) rather than forming excessively thick films. This partial action approach maintains manufacturing efficiency while achieving the required protective function
3Illumination intensity
If a reflective layer is provided on the electrode side to enhance light-emitting efficiency, then light utilization is improved, but the electrode structure becomes more complex
Solution Approach 1:
The patent makes the electrode layer perform multiple functions simultaneously: electrical conduction, light reflection, and physical gap provision. By integrating these functions into a single thick electrode structure formed by vacuum evaporation, the patent avoids the complexity of separate reflective layer and electrode layer structures
Solution Approach 2:
The patent merges the reflective layer and electrode layer into a single integrated electrode structure. The electrode is formed with sufficient thickness to provide both electrical functionality and optical reflection, eliminating the need for separate reflective coatings and reducing overall structural complexity
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
This configuration enhances mounting efficiency by effectively reflecting light and reducing the impact of dust and stress on the light-emitting layer, while allowing for easy electrode formation and improved reflective efficiency.
Implementation Method 1
a high-reflectivity metal layer disposed on a side that faces the semiconductor layer
Implementation Method 2
the plated metal layer has a thickness not less than 3 μm but not greater than 30 μm, and is made of high-reflectivity metals like Al or Ag, allowing for enhanced reflectivity and easy formation using electrolytic plating
Data Source
AI summary
The present invention is directed to the provision of a semiconductor light-emitting element that has an electrode formed with a desired thickness using a plated metal layer. A semiconductor light-emitting element for flip-chip mounting on a circuit substrate includes a semiconductor layer including a light-emitting layer, an N-side bump electrode for connecting the semiconductor layer to the circuit substrate, and a P-type bump electrode for connecting the semiconductor layer to the circuit substrate, wherein the N-side bump electrode and the P-type bump electrode each include an under-bump metal layer and a plated metal layer, the under-bump metal layer includes a high-reflectivity metal layer disposed on a side that faces the semiconductor layer and a metal layer disposed on a side opposite from the semiconductor layer, and the plated metal layer has a thickness not less than 3 μm but not greater than 30 μm.