Vertically Stacked Microdisplay Pixel for Transfer Simplification
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Solution Overview
Problem
Conventional pixel formation techniques for microdisplays are cumbersome due to the need for multiple transfer processes of small sub-pixels, result in increased pixel size due to thick black matrices, and difficulty in repairing defective sub-pixels, leading to reduced resolution and manufacturing complexity.
Innovation Solution
A vertically stacked pixel structure with a common anode layer and current blocking layer, allowing all sub-pixels to be connected to a single terminal and grown using a one-step in-situ process, simplifying the transfer process and enabling independent current control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If three sub-pixels are transferred onto a display substrate separately using pick and place process, then each sub-pixel can be positioned independently, but the manufacturing process becomes very cumbersome and time-consuming
Solution Approach 1:
The patent merges three separate transfer processes into a single process by bonding a substrate containing all three sub-pixels (R, G, B) together to the display substrate. This eliminates the need for repeated pick and place operations, significantly reducing manufacturing complexity while maintaining precise sub-pixel positioning.
Solution Approach 2:
The patent performs preliminary arrangement of all sub-pixels on a temporary substrate before transfer to the display substrate. This preliminary configuration allows all sub-pixels to be positioned and prepared in advance, simplifying the actual transfer process to a single bonding operation rather than multiple sequential placements.
2Object-affected harmful factors
If a thick black matrix is formed to prevent light mixing between sub-pixels, then color interference is prevented, but the distance between sub-pixels increases and pixel size increases
Solution Approach 1:
The patent transitions from horizontal arrangement of sub-pixels to vertical stacking in the depth direction. This dimensional change eliminates the need for lateral spacing between sub-pixels, allowing them to be positioned closely in the plane while maintaining optical isolation through the multi-layer structure. The black matrix layers are distributed vertically rather than requiring large horizontal gaps.
Solution Approach 2:
The patent implements nested black matrix layers within the multi-sub-pixel structure, with black matrix layers positioned between different sub-pixel layers vertically. This nested arrangement provides effective light isolation while minimizing the horizontal footprint of each pixel, enabling higher resolution displays.
3Ease of manufacture
If sub-pixels are arranged horizontally on the same plane, then conventional pixel formation is achieved, but repair of defective sub-pixels becomes very difficult
Solution Approach 1:
The patent segments the pixel structure into independently replaceable sub-pixel modules stacked vertically. Each sub-pixel can be individually accessed and replaced by removing only the defective sub-pixel from its vertical position, rather than requiring removal of entire pixel blocks or complex lateral access as in horizontal arrangements.
Solution Approach 2:
The patent inverts the conventional horizontal pixel structure to a vertical stack, which fundamentally changes the repair approach. Instead of requiring lateral access and block removal for repair, the vertical stacking allows top-down or bottom-up access to individual sub-pixels, simplifying the repair process to selective removal and replacement of single defective elements.
4Manufacturing precision
If sub-pixels are made very small (about 10 μm) to achieve high resolution, then display resolution improves, but the pick and place process becomes extremely challenging
Solution Approach 1:
The patent combines multiple small sub-pixels onto a single substrate that is then bonded to the display substrate in one operation. This merging approach allows precise positioning of multiple 10 μm sub-pixels to be achieved through substrate-level bonding rather than individual sub-pixel manipulation, making high-resolution manufacturing feasible.
Solution Approach 2:
The patent uses a master substrate as a template or copy holder containing pre-arranged sub-pixels. This master substrate serves as a copying medium that transfers the precise sub-pixel pattern to the display substrate through bonding, enabling replication of high-resolution patterns without direct manual placement of each tiny sub-pixel.
Data Source
AI summary
Disclosed are a unit pixel of a microdisplay and a method of manufacturing the same. In the unit pixel, each of the sub-pixels forming blue, green, and red light is vertically stacked on the growth substrate. As a result, the area of a unit pixel may be reduced, and transfer processes may be facilitated.