Micro-LED Display Pixel Formation via Laser Transfer
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Solution Overview
Problem
Conventional methods for forming high-density light-emitting diode (LED) displays face challenges in achieving high resolution and density, particularly for virtual reality and augmented reality applications, due to limitations in the pick and place technology for integrating micro-LEDs, which results in large pixels and impracticality for sub-pixel sizes less than 10 square microns.
Innovation Solution
A method involving the use of a driver wafer with an interconnect layer and driver circuits, where multiple optical wafers with micro-LEDs of different colors are selectively released and interconnected using a laser beam to form pixels with a thickness of no more than 10 microns, enabling direct integration and high-resolution displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional pick and place technology is used to integrate micro-LEDs, then the manufacturing process is simple, but the pixel size becomes large and high density cannot be achieved
Solution Approach 1:
The patent replaces the mechanical pick and place system with a direct wafer-to-wafer bonding process. Multiple optical wafers containing micro-LEDs are directly bonded to a driver wafer in a single alignment step, eliminating the need for individual micro-LED manipulation. This substitution of mechanical assembly with direct bonding enables sub-10-micron pixel sizes while maintaining manufacturing feasibility.
Solution Approach 2:
The patent merges multiple separate operations (individual micro-LED placement, alignment, and bonding) into a single integrated wafer bonding process. By combining the transfer of multiple optical wafers with direct bonding to the driver wafer in one step, the process achieves high density without requiring complex sequential manipulation of individual components.
2Manufacturing precision
If micro-LED thickness is reduced to 10 microns or less for high resolution, then the display density increases, but the manufacturing difficulty increases
Solution Approach 1:
The patent performs preliminary actions by fabricating complete optical wafers with arrays of micro-LEDs in advance, with each wafer containing multiple micro-LEDs of the same color. These pre-fabricated wafers are then directly bonded to the driver wafer, eliminating the need to manipulate individual thin micro-LEDs during assembly. This preliminary fabrication at the wafer level enables high resolution while simplifying the final integration process.
3Illumination intensity
If multiple optical wafers are used for different colors, then the display quality improves, but the integration process becomes more complex
Solution Approach 1:
The patent creates a universal integration platform where the driver wafer can simultaneously receive and integrate multiple optical wafers of different colors (red, green, blue) through a single bonding interface. The driver wafer's interconnect layer is designed to accommodate multiple optical wafers, enabling color integration without requiring separate processing steps for each color layer.
Solution Approach 2:
The patent merges the integration of multiple color layers into a single wafer bonding operation. Instead of sequentially assembling red, green, and blue micro-LEDs separately, the process bonds complete optical wafers containing arrays of same-color micro-LEDs directly to the driver wafer, combining multiple color integrations into one unified process step.
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 approach allows for the creation of high-resolution LED displays with a pixel pitch of less than 5 microns, achieving luminance of greater than 80K cd/square-m and enabling the integration of active matrix driver ICs to control micro-LEDs down to four per pixel, suitable for AR and VR applications.
Implementation Method 1
selectively applying a beam for releasing the first, the second, and the third plurality of light-emitting diodes
Data Source
AI summary
Apparatus and method relating generally to an LED display is disclosed. In such an apparatus, a driver die has a plurality of driver circuits. A plurality of light-emitting diodes, each having a thickness of 10 microns or less and discrete with respect to one another, are respectively interconnected to the plurality of driver circuits. The plurality of light-emitting diodes includes a first portion for a first color, a second portion for a second color, and a third portion for a third color respectively obtained from a first, a second, and a third optical wafer. The first, the second, and the third color are different from one another.