Multilayer Ti-Ni Barrier for Semiconductor Light Emitting Elements
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Solution Overview
Problem
Conventional semiconductor light emitting elements face issues with gold-tin solder bonding, where tin diffusion leads to electrode deformation, passivation film peeling, and functional impairment, and existing barrier layers are either ineffective or costly.
Innovation Solution
A multilayer barrier structure composed of alternately stacked titanium (Ti) and nickel (Ni) layers is used to prevent tin diffusion, enhancing the barrier effect while reducing fabrication costs and maintaining mass productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick barrier layer is used to enhance the barrier effect, then the barrier effect is improved, but the mass productivity is reduced due to cracks or peeling caused by stress
Solution Approach 1:
The barrier layer is divided into multiple thin layers (first barrier layer, second barrier layer, third barrier layer) with different materials and thicknesses. This segmentation allows each layer to contribute to the overall barrier effect while reducing individual layer stress, preventing cracks and peeling, thus maintaining mass productivity while enhancing the total barrier effect against Sn diffusion.
2Reliability
If platinum (Pt) is used to enhance the barrier effect, then the barrier effect is improved, but the fabrication cost is significantly increased
Solution Approach 1:
The patent replaces expensive platinum with cheaper materials (tungsten, titanium, nickel, chromium) for the barrier layers. These materials provide sufficient barrier effect against Sn diffusion at lower cost, making the fabrication process more economically viable while maintaining the required reliability.
Solution Approach 2:
The barrier structure uses a composite of multiple materials (tungsten, titanium, nickel, chromium, silicon oxide, silicon nitride) with different properties. This composite approach combines the advantages of each material to achieve an effective barrier against Sn diffusion without relying on expensive platinum, thus reducing fabrication cost while maintaining barrier effect.
3Productivity
If the barrier layer is made thinner to improve mass productivity, then the mass productivity is improved, but the barrier effect is reduced
Solution Approach 1:
Instead of using a single thin barrier layer, the patent segments the barrier function into multiple thin layers (first barrier layer 50-100nm, second barrier layer 50-100nm, third barrier layer 50-100nm). This segmentation allows the total barrier effect to be maintained or enhanced while keeping individual layers thin enough to avoid stress-induced cracks, thus improving mass productivity without sacrificing barrier effectiveness.
Solution Approach 2:
The multi-layer barrier structure uses different materials with complementary properties. The first barrier layer (tungsten or titanium) provides initial Sn diffusion resistance, the second barrier layer (nickel or chromium) adds intermediate protection, and the third barrier layer (silicon oxide or silicon nitride) provides final protection. This composite approach achieves superior overall barrier effect with thin layers, maintaining mass productivity.
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 multilayer barrier structure effectively blocks tin diffusion, preventing passivation film breakdown and electrode deformation, thus ensuring the reliability and functionality of semiconductor light emitting elements while being cost-effective and suitable for mass production.
Implementation Method 1
a first barrier layer comprising a first material different from the Au layer and having a first thickness; a second barrier layer comprising a second material different from the Au layer and having a second thickness; and a third barrier layer comprising a third material different from the Au layer and having a third thickness
Data Source
AI summary
A semiconductor light emitting element has an electrode formed on a semiconductor layer, a passivation film covering a part of a top surface of the electrode, and a multilayer film formed on the electrode. The multilayer film has at least one pair of a Ti layer and a Ni layer, the Ti layer and the Ni layer being stacked alternately in the multilayer film.