Active-Matrix LED Pixel Arrays via Substrate Removal and Bonding
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Solution Overview
Problem
The manufacturing complexity of light emitting diode (LED) arrays is high due to the need for large supporting substrates and high power consumption of driver circuitry, which reduces assembly yield and increases manufacturing costs.
Innovation Solution
Integrating light emitting elements formed on substrates with backplane devices and removing the substrates after bonding, simplifying the manufacturing process and improving efficiency by aligning and bonding light emitting elements directly with pixel circuits on the backplane, and using plasma activation for enhanced bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If LED arrays are manufactured by depositing materials on large supporting substrates with edge addressing connections, then the array size can be increased, but the supporting substrate size becomes larger than necessary and assembly yield greatly reduces
Solution Approach 1:
The invention divides the LED array manufacturing into separate stages: first fabricating LED chips on small individual substrates, then transferring and bonding them to the final display substrate. This segmentation allows each chip to be manufactured independently on optimized small substrates, avoiding the need for large supporting substrates and thereby maintaining high assembly yield while achieving large overall array sizes.
Solution Approach 2:
The invention transitions from a planar manufacturing approach (depositing materials directly on large substrates) to a three-dimensional assembly approach (bonding pre-fabricated LED chips from different substrates onto the display substrate). This dimensional change enables efficient use of substrate space and simplifies the bonding process, resolving the contradiction between array size and assembly yield.
2Ease of operation
If driver circuitry is integrated with LED arrays, then the arrays can be controlled, but the power consumption increases and manufacturing complexity increases
Solution Approach 1:
The invention merges the LED chip bonding process with the driver circuit integration by simultaneously bonding LED chips to both the display substrate and the driver circuit substrate. This combined approach eliminates separate manufacturing steps, reduces overall manufacturing complexity, and enables controlled operation of large LED arrays with efficient power management.
3Area of moving object
If contact pads are made very small to increase array size, then the array density increases, but the assembly yield greatly reduces
Solution Approach 1:
The invention performs preliminary bonding of LED chips to intermediate substrates before final assembly. This preliminary action allows for optimized contact pad designs on small substrates where yield is not compromised, and the pre-bonded units can then be efficiently assembled into large high-density arrays without the yield penalties associated with directly bonding tiny contact pads on large substrates.
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 reduces manufacturing complexity, improves yield, and enables the production of high-density, high-resolution active-matrix LED pixels with lower power consumption and larger display areas, while eliminating the need for complex substrate handling and driver circuitry.
Implementation Method 1
before the bonding, pretreating with plasma activation at least one of surfaces of the first conductive outer layers of the first light emitting elements or a surface of the backplane device including surfaces of the conductive outer layers of the first pixel circuits
Implementation Method 2
each of the first light emitting elements including first semiconductor layers epitaxially grown on the first substrate
Data Source
AI summary
Integrated active-matrix light emitting pixel arrays based displays and methods of fabricating the integrated displays are provided. One of the methods includes: forming a plurality of light emitting elements on a substrate, each of the light emitting elements including multiple semiconductor layers epitaxially grown on the substrate and being configured to emit light with a single color, integrating the light emitting elements formed on the substrate with a backplane device, such that each of the light emitting elements is bonded and conductively coupled to a respective pixel circuit in the backplane device, and then removing the substrate from the light emitting elements that remain integrated with the backplane device. Active-matrix multi-color pixel arrays can be formed by sequentially integrating different color light emitting element arrays on the backplane device or depositing different color phosphor or quantum dot materials on single color light emitting element arrays integrated on the backplane device.