Micro-LED Pad Structure to Avoid Etch-Damaged Electrode Connections
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The formation of planarization and conductive layers in Micro-LED displays damages the connection between the lower electrode and the corresponding pad, leading to poor reliability of the Micro-LED display device due to the etching process used in patterning these layers.
Innovation Solution
The display device design includes a circuit substrate with pad sets where the second pad surrounds the first pad, allowing for electrical connection between the second electrode and the second pad through heat treatment, avoiding the need for an etching process and enhancing reliability, and further incorporates a transparent conductive layer that covers the second electrode, sidewall of the light-emitting stack, and second pad to prevent damage during patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching process is used to pattern planarization layer or conductive layer, then manufacturing precision is improved, but reliability deteriorates due to damage to the connection between lower electrode and pad
Solution Approach 1:
The lower electrode is designed to extend beyond the light-emitting stack boundary in advance, creating an exposed portion that protrudes from the stack. This preliminary extension ensures that the electrode connection area is positioned away from the light-emitting stack, so that subsequent planarization and patterning processes do not damage the electrode-pad connection, thus resolving the contradiction between achieving precise patterning and maintaining connection reliability
Solution Approach 2:
The patent introduces an insulating layer that covers the light-emitting stack and extends to cover the exposed portion of the lower electrode. This insulating layer acts as a protective intermediary that prevents the etchant from reaching and damaging the electrode-pad connection during the patterning process, while still allowing the conductive layer to be properly formed and connected
2Ease of manufacture
If planarization layer is formed to fill topography difference, then ease of manufacture is improved, but reliability deteriorates due to etchant damage during subsequent patterning
Solution Approach 1:
The lower electrode is pre-positioned to extend beyond the light-emitting stack, creating an exposed portion that will serve as the connection area. This preliminary action ensures that when the planarization layer is formed to fill the topography difference, the electrode connection area remains accessible and protected from subsequent etching processes that pattern the conductive layer
Solution Approach 2:
The insulating layer is introduced as a protective intermediary that covers both the light-emitting stack and the exposed portion of the lower electrode. This allows the planarization layer to be formed easily to fill topography differences while the insulating layer protects the electrode connection area from damage during subsequent conductive layer patterning
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 design improves the reliability of the Micro-LED display by preventing damage to the electrical connections during the formation of planarization and conductive layers, ensuring stable operation and increased durability.
Implementation Method 1
allowing for electrical connection between the second electrode and the second pad through heat treatment
Data Source
AI summary
A display device includes a circuit substrate, a plurality of pad sets and a plurality of light-emitting elements. The plurality of pad sets is disposed on the circuit substrate, and each pad set includes a first pad and a second pad surrounding the first pad. The plurality of light-emitting elements is disposed above the circuit substrate, and each light-emitting element includes a first electrode, a second electrode and a light-emitting stack between the first electrode and the second electrode, wherein the first electrode is electrically connected to the first pad, the second electrode is electrically connected to the second pad, and an orthographic projection of the second electrode on the circuit substrate is overlapped with an orthographic projection of the first pad on the circuit substrate.