TiN Barrier Electrode Structure to Suppress Ag Migration in LEDs
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Solution Overview
Problem
Conventional techniques fail to adequately suppress electrode discoloration and emission failure due to silver (Ag) migration in AlGaN-based semiconductor light-emitting devices, particularly for p-type electrodes with larger areas, when using Ag-containing joint materials.
Innovation Solution
A semiconductor light-emitting device design featuring a p-type AlGaN-based semiconductor layer with a p-type electrode and a barrier layer containing a TiN layer, where the barrier layer is positioned closer to the pad than the ohmic metal layer, and a surface diffusion inhibiting surface is formed in a circular pattern to prevent Ag migration, and the ohmic metal layer is free of Ag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a joint material containing Ag is used for mounting semiconductor light-emitting devices, then electrical conductivity is improved, but Ag migration occurs which causes electrode discoloration and emission failure
Solution Approach 1:
The patent introduces a barrier layer as an intermediary between the Ag-containing joint material and the electrode. This barrier layer prevents direct contact and migration of Ag ions into the electrode while still allowing the joint material to provide its electrical conductivity function. The barrier layer acts as a mediator that resolves the contradiction by blocking the harmful Ag migration path.
Solution Approach 2:
The patent extracts the harmful Ag migration issue by removing the direct interface between Ag-containing joint material and the electrode. By introducing a separate barrier layer, the Ag migration path is effectively taken out or blocked, preventing the harmful interaction while maintaining the electrical connection function.
2Reliability
If conventional barrier structures are used, then some protection against Ag migration is achieved, but detrimental effects such as electrode discoloration and emission failure are not sufficiently suppressed
Solution Approach 1:
The patent employs a composite barrier layer structure combining multiple materials (TiN layer and W layer) with different properties. The TiN layer provides excellent barrier properties against Ag migration, while the W layer adds mechanical strength and additional barrier characteristics. This composite structure achieves superior protection compared to single-material barriers, effectively suppressing electrode discoloration and emission failure.
Solution Approach 2:
The patent applies local quality by creating a barrier layer with specific material composition and thickness tailored for the Ag migration barrier function. The TiN layer is specifically positioned and dimensioned to provide optimal protection at the critical interface where Ag migration occurs, addressing the local harmful effect with a customized solution.
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 design effectively inhibits Ag migration, preventing electrode discoloration and emission failure, even when using Ag-containing joint materials, thereby enhancing the reliability of semiconductor light-emitting devices.
Implementation Method 1
when a region of the barrier layer that does not overlap an electrical connection region between the pad and the barrier layer in a top view is defined as a surface diffusion inhibiting surface, the surface diffusion inhibiting surface is formed in a circular pattern
Data Source
AI summary
Provided is a semiconductor light-emitting device for which detrimental effects such as discoloration of an electrode or emission failure due to migration are suppressed even when a joint material containing Ag is used, and a method of producing the same. The semiconductor light-emitting device includes a p-type semiconductor layer, a p-type electrode provided on the p-type semiconductor layer, and a pad provided on the p-type electrode. The p-type electrode at least has an ohmic metal layer placed on the p-type semiconductor layer side and a barrier layer that is placed closer to the pad than the ohmic metal layer and includes a TiN layer. In a top view, when a region of the barrier layer that does not overlap an electrical connection region between the pad and the barrier layer is defined as a surface diffusion inhibiting surface, the surface diffusion inhibiting surface is formed in a circular pattern.