μLED Mesa Electrode Alignment for Bonding Yield
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Solution Overview
Problem
The manufacturing process of micro light emitting diodes (μLEDs) faces challenges such as tilt phenomena during bonding to external substrates due to electrode height differences, leading to poor bonding yields and difficulty in forming protective layers over tiny features, which limits the size of the N-type electrode and overall yield.
Innovation Solution
A μLED design with epitaxial stacked layers and electrodes on mesa portions of the same horizontal plane, where the second electrode contacts the doped semiconductor layers, eliminating the need for a protective layer and allowing for a simpler structure and higher yield, with a manufacturing method that forms these structures through etching and insulation layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two electrodes are disposed on mesa portions with different horizontal heights, then the electrical connection is achieved, but the tilt phenomenon occurs during bonding leading to poor bonding yield
Solution Approach 1:
The patent applies equipotentiality by making both mesa portions (first and second mesa portions) have the same horizontal height, ensuring that the electrodes are at the same potential level. This eliminates the tilt phenomenon during bonding and improves bonding yield, while still achieving proper electrical connection through the doped semiconductor layers.
2Reliability
If a protective layer is formed over tiny features (hole below 10 μm×10 μm), then electrical isolation is achieved, but the manufacturing process becomes more difficult and electrode size is limited
Solution Approach 1:
The patent extracts and eliminates the protective layer from the structure by designing the second electrode to directly contact the doped semiconductor layer without requiring a protective layer. This removes the manufacturing difficulty associated with forming protective layers over tiny features while still achieving the necessary electrical isolation through the inherent properties of the doped semiconductor layer and electrode configuration.
Data Source
AI summary
A μLED including an epitaxial stacked layer, a first electrode and a second electrode is provided. The epitaxial stacked layer includes a first type doped semiconductor layer, a light emitting layer and a second type doped semiconductor layer. The epitaxial stacked layer has a first mesa portion and a second mesa portion to form a first type conductive region and a second type conductive region respectively. The first electrode is disposed on the first mesa portion. The second electrode is disposed on the second mesa portion. The second electrode contacts the first type doped semiconductor layer, the light emitting layer and the second type doped semiconductor layer located at the second mesa portion. Moreover, a manufacturing method of the μLED is also provided.