Stacked LEDoS Microdisplay Without Color Filters for Fine Pixel Arrays
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Solution Overview
Problem
Conventional microdisplay panels face challenges in mass-producing high-pixel density LEDoS microdisplays due to ultra-fine arrangement constraints and the need for a color filter, leading to high manufacturing costs and low yield.
Innovation Solution
A vertically stacked microdisplay panel design that eliminates the need for a color filter by using a back wafer with CMOS electrode pads and LED stacks that emit specific colors, employing a bypass layer to divert current and a ceramic bonding layer to enhance etching and reduce short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional microdisplay panel manufacturing methods are used with color filters, then color display is achieved, but manufacturing complexity and cost increase while yield decreases
Solution Approach 1:
The patent removes the color filter component entirely from the microdisplay structure. Instead of using a color filter layer to achieve color display, the invention employs micro-LEDs that inherently emit specific colors (red, green, blue) without requiring additional color filtering layers, thereby simplifying the manufacturing process and reducing device complexity
Solution Approach 2:
The patent uses transfer printing technology to replicate and transfer micro-LED arrays from a source wafer to the final substrate. This copying approach enables mass production of high-pixel-density displays by efficiently transferring millions of micro-LEDs in an organized manner, improving manufacturing ease and yield
2Manufacturing precision
If ultra-fine pixel arrangement is implemented for high pixel density, then display resolution improves, but manufacturing precision requirements increase and yield decreases
Solution Approach 1:
The patent pre-arranges micro-LEDs in their final high-pixel-density configuration on a source wafer before transfer. This preliminary action allows for precise pixel arrangement to be achieved once during the transfer process rather than requiring ultra-precise placement of each individual micro-LED during final assembly, thereby maintaining manufacturing precision while enabling mass production
Solution Approach 2:
The patent introduces a source wafer as an intermediary substrate that temporarily holds the micro-LED arrays in their precise final configuration. This intermediary approach allows high-pixel-density arrangements to be fabricated and verified before transfer, ensuring manufacturing precision is achieved without compromising mass production capability
3Speed
If micro-LEDs are used instead of other display technologies, then response speed and luminous efficiency improve, but manufacturing difficulty increases due to ultra-small size
Solution Approach 1:
The patent replaces traditional mechanical picking and placing methods with transfer printing technology that uses controlled stress and release mechanisms to transfer micro-LEDs. This substitution eliminates the need for complex mechanical handling of ultra-small components, maintaining the ease of manufacture while preserving the fast response speed and high luminous efficiency benefits of micro-LEDs
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
Improves color quality, process complexity, and productivity, enabling high-resolution microdisplays with ultra-fine pixels and increased yield using larger wafers, reducing short circuit defects, and simplifying the exposure process.
Implementation Method 1
each LED stack emits only light of a specific color by blocking the light generated from at least one light-emitting portion
Implementation Method 2
employing a bypass layer to divert current and a ceramic bonding layer to enhance etching and reduce short circuits
Data Source
AI summary
The present invention relates to a vertically stacked LEDoS micro display panel and a manufacturing method therefor, in which an engineering monolithic epitaxy wafer is used when bonding a front wafer and a back wafer to each other, thus making a process for aligning an LED laminate with a CMOS electrode pad unnecessary, and at the same time, each LED laminate emits only light of a specific color, thus making a color filter unnecessary.