LED Contact Electrode Barrier Structure Against Tin Corrosion
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Solution Overview
Problem
In light-emitting diodes, the non-optimal etched angle of the insulation layer's wall creates gaps between the insulation layer and pad electrodes, allowing tin to corrode gold-containing ohmic electrodes, affecting the reliability of the device.
Innovation Solution
The light-emitting device incorporates a semiconductor epitaxial unit with ohmic contact layers and electrode barrier layers, including a first and second contact electrode with specific metal compositions and structures to prevent tin corrosion, and a bonding layer that reduces total reflection and enhances current spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional insulation layer structure is used, then the manufacturing process is simple, but gaps form between the insulation layer and pad electrode, allowing tin corrosion
Solution Approach 1:
The contact electrode is divided into multiple functional layers: a base layer (first material layer) and a protective layer (second material layer). This segmentation allows the base layer to provide electrical connection while the protective layer prevents tin corrosion, resolving the contradiction between simple structure and corrosion resistance.
Solution Approach 2:
The contact electrode uses a composite structure with at least two different materials. The first material layer (e.g., gold-containing ohmic electrode) provides electrical conductivity, while the second material layer (e.g., tin barrier layer) provides corrosion protection. This composite approach achieves both electrical functionality and corrosion resistance without excessive complexity.
2Reliability
If the insulation layer wall etched angle is not optimized, then the manufacturing process is easier, but gaps form between the insulation layer and pad electrode
Solution Approach 1:
The protective layer is formed on the contact electrode before the insulation layer is deposited. This preliminary action ensures that the protective layer is already in place to prevent tin corrosion, even if the insulation layer etched angle is not perfectly optimized, thereby maintaining connection reliability without requiring extremely precise etching.
Solution Approach 2:
The second material layer acts as a cushioning protective barrier between the tin-containing pad electrode and the gold-containing ohmic electrode. This beforehand cushioning prevents tin from migrating and corroding the gold layer, compensating for potential gaps caused by non-optimal etching angles.
3Reliability
If a single-layer ohmic electrode is used, then the device structure is simpler, but tin can corrode the gold-containing electrode
Solution Approach 1:
The contact electrode is segmented into a first material layer (gold-containing ohmic electrode) and a second material layer (protective barrier layer). This segmentation provides both electrical functionality and corrosion protection, achieving reliable electrode protection while maintaining reasonable structural simplicity.
Solution Approach 2:
The second material layer serves as an intermediary barrier between the tin-containing pad electrode and the gold-containing ohmic electrode. This intermediary layer prevents direct contact and corrosion while maintaining the electrical connection function, resolving the contradiction between simplicity and protection.
Data Source
AI summary
A light-emitting device includes a semiconductor epitaxial unit, a first contact electrode, and a second contact electrode. The semiconductor epitaxial unit includes a first semiconductor layer, a second semiconductor layer, and an active layer. The first contact electrode and the second contact electrode are disposed on the semiconductor epitaxial unit, and are electrically connected to the first semiconductor layer and the second semiconductor layer, respectively. The first contact electrode includes an ohmic contact layer and a first electrode barrier layer. The second contact electrode includes an ohmic contact layer and a second electrode barrier layer. The ohmic contact layer of the first contact electrode includes a first ohmic contact layer. The ohmic contact layer of the second contact electrode includes a second ohmic contact layer. The second contact electrode further includes another first ohmic contact layer disposed between the second ohmic contact layer and the second electrode barrier layer.