Micro LED Display Substrate Segmentation for Yield Recovery
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Solution Overview
Problem
In display technology, local dirt or dust on the anode or light-emitting layer can lead to poor bonding, resulting in unlit sub-pixels and reduced yield and display effect in micro Light-Emitting Diode (LED) displays.
Innovation Solution
A method of fabricating a display substrate with pixel regions featuring an anode, a light-emitting layer, and a cathode, where the light-emitting layer is split into multiple units, and the anode and cathode are connected through an insulating layer with via holes, allowing for separate bonding and etching to prevent short circuits and ensure light emission even with local contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the anode and light-emitting layer are bonded together in a micro LED display, then the display structure is formed, but local dirt or dust causes poor bonding resulting in unlit sub-pixels and reduced yield
Solution Approach 1:
The anode and cathode are divided into multiple independent sub-electrodes corresponding to individual sub-pixels. Each sub-electrode can be independently bonded to the light-emitting layer, so that bonding failures in one sub-pixel do not affect other sub-pixels. This segmentation allows well-bonded sub-pixels to continue functioning even when some experience bonding defects due to local contamination.
Solution Approach 2:
The patent applies different treatments to different regions: well-bonded sub-pixels maintain their original structure and function, while poorly-bonded sub-pixels have their corresponding sub-electrodes removed through selective wet etching. This local quality approach ensures that only affected areas are modified, preserving the functionality of healthy sub-pixels and maximizing overall display yield.
2Reliability
If the entire anode or cathode is removed due to poor bonding in a local region, then bonding quality is improved, but the entire sub-pixel becomes unlit
Solution Approach 1:
The anode and cathode are segmented into multiple sub-electrodes, each corresponding to a specific sub-pixel. This segmentation allows selective removal of only the sub-electrodes in poorly-bonded regions through localized wet etching, while sub-electrodes in well-bonded regions remain intact and continue to conduct current to their corresponding light-emitting units.
Solution Approach 2:
The patent implements local quality by applying selective wet etching only to regions with poor bonding between the sub-electrode and light-emitting layer. The etching process is spatially controlled to remove conductive material only where bonding defects exist, preserving conductive pathways in well-bonded regions and maintaining light emission in those sub-pixels.
3Device complexity
If the anode and cathode are directly connected, then the structure is simplified, but short circuits may occur in poorly-bonded regions
Solution Approach 1:
The patent performs preliminary assessment of bonding quality before final assembly completion. By evaluating bonding characteristics early in the manufacturing process, the system can identify poorly-bonded regions and apply selective wet etching to remove sub-electrodes in those areas before they could cause short circuits, preventing the problem rather than reacting to it.
Solution Approach 2:
The patent converts the potentially harmful effect of poor bonding (which could cause short circuits) into a beneficial selection criterion. By using bonding quality as a guide for selective etching, the process identifies and removes only the problematic sub-electrodes, transforming what would be a defect into a quality control mechanism that eliminates future short circuit risks.
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 the yield and display effect by ensuring that well-bonded light-emitting units continue to emit light, even if the anode or light-emitting layer is locally dirty or dusty, thereby preventing the entire sub-pixel from being unlit.
Implementation Method 1
thinning the second substrate using a mixed indicator, such that a thickness of the second substrate is less than or equal to 100 microns
Implementation Method 2
performing wet etching by using the insulating layer as a mask, to remove the anode in a poorly-bonded region
Implementation Method 3
forming the light-emitting layer in at least one pixel region into the plurality of light-emitting units spaced apart from each other includes splitting the light-emitting layer into the plurality of light-emitting units spaced apart from each other by a coupled plasma etching process
Data Source
AI summary
The present disclosure provides display substrate and a fabrication method thereof, a display panel and a display device. The display substrate has a plurality of pixel regions, and includes an anode, a light-emitting layer and a cathode in each pixel region. In each pixel region, the light-emitting layer includes a plurality of light-emitting units spaced apart from each other, both the anode and the cathode are conductive layers each having an integral structure, and the plurality of light-emitting units are connected to the anode and the cathode, respectively.