Micro-LED Isolation Walls for UV Subpixel Crosstalk
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Solution Overview
Problem
Micro-LED displays using UV-emitting micro-LEDs and color conversion layers face challenges with emission crosstalk and color mixing due to the low transmittance of existing opaque materials in the UV range, which affects display brightness and color gamut.
Innovation Solution
The method involves depositing a first material over a substrate with micro-LEDs, forming trenches that extend to or below the light-emitting layers, and then depositing a second opaque material that covers the first material and extends into the trenches. This creates isolation walls that are vertically higher than the top surface of the first material, effectively blocking UV light and preventing crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing opaque materials are used to separate subpixels, then subpixel isolation is achieved, but UV light transmittance is too high causing crosstalk and color mixing
Solution Approach 1:
The patent uses a composite material structure consisting of a transparent dielectric material (such as silicon dioxide or silicon nitride) combined with a metal layer (such as aluminum or silver) to create an opaque isolation wall. This composite structure provides both UV light blocking capability and structural stability, resolving the contradiction between achieving subpixel isolation and preventing UV light transmission.
Solution Approach 2:
The isolation wall is designed with spatially varying properties: the dielectric material provides mechanical support and adhesion, while the metal layer provides UV light blocking. This local differentiation of material functions within the isolation wall structure enables simultaneous achievement of structural integrity and optical isolation.
2Adaptability or versatility
If pick-and-place step is used to transfer micro-LEDs, then color integration is achieved, but placement accuracy requirements limit throughput and yield
Solution Approach 1:
The patent merges the micro-LED fabrication process with the display substrate fabrication process by forming isolation walls directly on the display substrate before micro-LED transfer. This integration eliminates the need for separate pick-and-place operations with stringent accuracy requirements, thereby improving throughput and yield while achieving color integration.
Solution Approach 2:
The isolation walls are formed in advance on the display substrate before the micro-LEDs are transferred and positioned. This preliminary action simplifies subsequent processing steps and reduces the complexity of placement operations, enabling higher productivity without compromising color integration.
3Productivity
If monochrome micro-LEDs with color conversion agents are used, then pick-and-place step is bypassed, but UV light crosstalk between subpixels increases
Solution Approach 1:
The patent introduces an intermediary opaque isolation wall structure between adjacent micro-LED subpixels that converts UV light. This intermediary structure prevents UV light from one subpixel from reaching adjacent subpixels, thereby eliminating UV crosstalk while maintaining the simplified monochrome micro-LED fabrication process with color conversion agents.
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 enhances display brightness and color gamut by reducing light losses and color crosstalk, while also improving the manufacturing process by allowing for increased opacity and reduced color conversion layer deposition accuracy issues.
Implementation Method 1
depositing a first material over a substrate having a plurality of micro-LEDs such that the plurality of micro-LEDs are covered by the first material and the first material fills gaps laterally separating the micro-LEDs
Implementation Method 2
The second material is an opaque material... effectively blocking UV light and preventing crosstalk
Data Source
AI summary
A method for manufacturing micro-LED displays includes depositing a first material over a substrate having a plurality of micro-LEDs such that the plurality of micro-LEDs are covered by the first material and the first material fills gaps laterally separating the micro-LEDs, removing a portion of the first material from the gaps that laterally separate the plurality of micro-LEDs to form trenches that extend to or below light-emitting layers of the micro-LEDs, depositing a second material over the substrate such that the second material covers the first material and extends into the trenches, and removing a portion of the first and second material over the plurality of micro-LEDs to expose top surfaces of the plurality of micro-LEDs and such that isolation walls positioned in the gaps between the plurality of micro-LEDs extend vertically higher than the top surface of the first material.