Micro-LED Pixel Transfer Using Temporary Substrate Packaging
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Solution Overview
Problem
The existing methods for transferring micro-LEDs are time-consuming as they involve transferring one micro-LED at a time to a permanent substrate, which hampers efficiency in mass production.
Innovation Solution
A method involving forming micro-LED chips on a base with epitaxial stacked layers and electrodes, attaching them to a temporary substrate, forming a light shielding layer, and then a light-transmissible packaging layer to create micro-LEDs that are separated and transferred as pixels to a permanent substrate, allowing for simultaneous transfer of multiple micro-LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If one micro-LED is transferred from a wafer to the permanent substrate at one time, then the transfer precision is maintained, but the transfer efficiency is low and the process is time-consuming
Solution Approach 1:
Multiple micro-LED chips are transferred together as a group rather than individually. The method combines multiple transfer operations into a single process step by maintaining the relative positions of micro-LEDs on the wafer and transferring them collectively to the permanent substrate, significantly improving transfer efficiency and reducing time consumption.
Solution Approach 2:
The permanent substrate is prepared in advance with corresponding recesses and electrode structures that match the arrangement of micro-LEDs on the wafer. This preliminary preparation allows multiple micro-LEDs to be transferred and positioned simultaneously without requiring individual alignment operations, thereby increasing productivity while maintaining precision.
2Productivity
If multiple micro-LEDs are transferred simultaneously, then the transfer efficiency is improved, but the complexity of the transfer process increases
Solution Approach 1:
The transfer process is segmented into distinct stages: preparation of the permanent substrate with matching recesses, group transfer of micro-LEDs maintaining their wafer positions, and subsequent individual pixel formation. This segmentation simplifies the overall process by breaking down the complex simultaneous transfer into manageable steps with clear objectives for each stage.
Solution Approach 2:
The method uses an intermediary approach where the permanent substrate is first prepared with recesses and electrode structures that serve as receiving positions for the micro-LEDs. This intermediary preparation step simplifies the transfer process by providing pre-defined positions, reducing the complexity of simultaneous positioning and alignment.
3Manufacturing precision
If micro-LED chips are closely arranged to form pixels, then the display resolution is improved, but the gap regions between chips are reduced making light shielding more difficult
Solution Approach 1:
The light shielding layer is applied locally in the gap regions between adjacent micro-LED chips rather than uniformly across the entire substrate. This localized application of light shielding material effectively prevents light leakage between chips while maintaining the close arrangement necessary for high display resolution, addressing the specific problem areas without compromising overall pixel density.
Data Source
AI summary
A method for transferring micro light emitting diodes (micro-LEDs) includes forming a plurality of micro light emitting diode (micro-LED) chips having an epitaxial stacked layer and an electrode on a base; attaching the electrodes of the micro-LED chips to a temporary substrate and removing the base from the micro-LED chips; forming a light shielding layer on the temporary substrate; forming a light-transmissible packaging layer to cover the light shielding layer and the micro-LED chips; removing the temporary substrate to form a light emitting assembly; dividing the light emitting assembly to separate a plurality of pixels constituted by the micro-LEDs; and transferring the pixels to a permanent substrate.