LED Electrode Fabrication Preventing Lateral Erosion
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Solution Overview
Problem
In the fabrication of AlGaInP-based light-emitting diodes, the formation of a closed loop by the bonding wire electrode and extended electrode during roughening affects the roughening effect, leading to directional motion of charged particles and potential lateral erosion of the extended electrode, resulting in fragile metal contacts or lift-off.
Innovation Solution
The extended electrode is fabricated before roughening, and the bonding pad electrode is formed after roughening, with a metal mask layer used to prevent the formation of a closed loop and protect the extended electrode from erosion, ensuring random motion of charged particles and preventing lateral erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bonding pad electrode and extended electrode are simultaneously fabricated and form a closed loop during roughening, then the electrodes can be formed in one process step, but the charged particles in the roughening solution experience directional motion due to magnetic field, causing lateral erosion of the extended electrode and potential lift-off
Solution Approach 1:
The electrode fabrication process is segmented into two separate steps: first forming the extended electrode, then forming the bonding pad electrode after roughening. This segmentation breaks the closed loop formation, eliminating the magnetic field effect that causes lateral erosion during roughening, while still maintaining efficient fabrication through sequential processing.
2Manufacturing precision
If the extended electrode is fabricated before roughening, then the bonding pad electrode can be formed after roughening to avoid closed loop formation, but an additional process step is required
Solution Approach 1:
The extended electrode is fabricated in advance before the roughening process. This preliminary action allows the roughening to proceed without magnetic field interference from closed loop formation, ensuring high roughening quality. The bonding pad electrode is then formed after roughening, completing the electrode structure in an optimized sequence.
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 method improves the roughening ratio and light extraction rate of the LED, enhancing luminance by preventing directional motion and erosion, resulting in a more stable and efficient light-emitting diode fabrication process.
Implementation Method 1
forming a roughening surface via chemical etching of the exposed second-type semiconductor layer
Implementation Method 2
performing thermal treatment to form ohmic contact with the second-type semiconductor layer
Data Source
AI summary
A method of fabricating an LED includes: providing an epitaxial structure having a growth substrate, a first-type semiconductor layer, an active layer and a second-type semiconductor layer; forming an extended electrode and performing thermal treatment to form ohmic contact with the second-type semiconductor layer; providing a temporary substrate bonded with the epitaxial structure, and removing the growth substrate to expose the surface of the first-type semiconductor layer; forming an ohmic contact layer, a mirror layer and a bonding layer over the exposed surface of the first-type semiconductor layer; providing a conductive substrate bonded with the bonding layer, and removing the temporary substrate to expose part of the surface of the second-type semiconductor layer and the extended electrode; forming a roughening surface via etching of the exposed second-type semiconductor layer; and providing a bonding wire electrode forming a closed loop with the extended electrode.