Vertical Micro-LED Side Electrode Design for Optical Efficiency
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Solution Overview
Problem
The existing micro-LED technology with vertical structures faces challenges such as increased processing complexity, reduced optical efficiency due to imperfect optical transmittance of the top electrode, side light leakage, limited heat dissipation, and complex N electrode formation on the display substrate, which affect the efficiency and lifetime of high-resolution displays.
Innovation Solution
The method involves forming vertical micro-LEDs on a growth substrate with a first electrode on top and a second electrode on the side surface, allowing for testing and transfer to a display substrate, reducing back-end fabrication processes and improving micro-LED performance by forming side-contact electrodes on the growth substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the top electrode is made transparent to allow light emission, then optical efficiency is improved, but electrical contact reliability deteriorates
Solution Approach 1:
The electrode system is segmented into two independent electrodes: a transparent top electrode for light emission and an opaque side electrode for reliable electrical contact. This segmentation allows each electrode to be optimized for its specific function without compromising the other.
Solution Approach 2:
The electrical contact function is moved from the top surface (2D plane) to the side surface (vertical dimension). By forming the second electrode on the side surface of the micro-LED, the patent creates a three-dimensional electrode configuration that separates the optical and electrical functions spatially.
2Reliability
If deep etching is performed to reach the heavy doping region for N electrode formation, then electrical contact is improved, but processing complexity increases
Solution Approach 1:
Instead of etching deeply in the vertical direction to reach the heavy doping region, the patent forms the N electrode on the side surface of the micro-LED. This lateral approach eliminates the need for deep etching while still achieving reliable electrical contact with the n-EPI region.
Solution Approach 2:
The side surface of the micro-LED is prepared in advance for electrode formation by controlling the etching depth to expose the appropriate region. This preliminary preparation simplifies subsequent electrode deposition processes.
3Reliability
If the top electrode is made opaque to improve electrical contact, then electrical contact reliability is improved, but optical efficiency deteriorates
Solution Approach 1:
The electrode system is segmented into two independent electrodes: a transparent top electrode for light emission and an opaque side electrode for reliable electrical contact. This segmentation allows each electrode to be optimized for its specific function without compromising the other.
4Manufacturing precision
If micro-LED size is reduced for high-resolution display, then definition is improved, but heat dissipation capability deteriorates
Solution Approach 1:
Heat dissipation is enhanced by adding a lateral heat conduction path through the side electrode. The side electrode serves dual functions: electrical contact and heat dissipation, providing an additional thermal management dimension for small-sized micro-LEDs.
5Adaptability or versatility
If N electrode is formed after transfer to display substrate, then process flexibility is improved, but manufacturing complexity increases
Solution Approach 1:
The N electrode is formed on the growth substrate before the micro-LED transfer process. This preliminary formation simplifies the post-transfer manufacturing steps on the display substrate, as only the P electrode and connection structures need to be formed afterward.
Data Source
AI summary
A display device manufacturing method, display device and electronics apparatus are provided. The display device manufacturing method comprises: forming the vertical micro-LEDs on a growth substrate: forming a first electrode on top of each of the vertical micro-LEDs; forming a second electrode on side surface of each of the vertical micro-LEDs; and transferring the vertical micro-LEDs from the growth substrate to a display substrate of a display device. An embodiment of this invention can reduce the back-end fabrication process on a display substrate after transfer.