3D Micro Display RGB Stacking With Low-Temperature Oxide Bonding
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Solution Overview
Problem
Current methods for constructing RGB LEDs are inefficient and costly, particularly due to issues with thermal expansion coefficient mismatches and high processing temperatures, which lead to defects and increased costs in producing white light-emitting diodes, and existing layer transfer techniques for displays are limited by high temperatures and yield issues.
Innovation Solution
The use of smart layer transfer techniques such as ion-cut, laser lift-off, and oxide-to-oxide bonding to stack red, green, and blue LEDs, allowing for efficient construction of RGB LEDs with reduced thermal stress and lower processing temperatures, and the integration of junction-less transistors on glass substrates at temperatures below 400°C for display applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods for constructing RGB LEDs are used, then white light-emitting diodes can be produced, but thermal expansion coefficient mismatches and high processing temperatures lead to defects and increased costs
Solution Approach 1:
The patent segments the RGB LED construction into separate red, green, and blue LED layers that are individually fabricated and then stacked. This segmentation allows each layer to be optimized independently and bonded using low-temperature oxide-to-oxide bonding, avoiding the high processing temperatures and thermal expansion mismatches that occur in conventional monolithic approaches.
Solution Approach 2:
The patent introduces oxide bonding layers as intermediaries between the different LED layers. These oxide layers serve as buffer and bonding interfaces that enable low-temperature bonding (below 400°C) between the red, green, and blue LED layers, eliminating the need for high-temperature processing and reducing thermal stress and defects.
2Manufacturing precision
If existing layer transfer techniques are used for displays, then display structures can be formed, but high temperatures and yield issues limit effectiveness
Solution Approach 1:
The patent changes the temperature parameter from conventional high-temperature processing to low-temperature oxide-to-oxide bonding (below 400°C). This parameter change enables the use of glass substrates and junction-less transistors that cannot withstand high temperatures, thereby improving yield and manufacturing precision for display applications.
Solution Approach 2:
The patent replaces conventional mechanical bonding and high-temperature processing with oxide-to-oxide bonding at low temperatures. This substitution enables precise layer transfer and stacking without the thermal damage and yield losses associated with traditional methods, allowing for high-performance display fabrication.
3Strength
If high processing temperatures are used for LED construction, then bonding can be achieved, but thermal stress and defects increase
Solution Approach 1:
The patent changes the bonding temperature parameter from high temperature to low temperature (below 400°C) oxide-to-oxide bonding. This parameter change maintains sufficient bonding strength between LED layers while dramatically reducing thermal stress and preventing the formation of defects that occur with conventional high-temperature processing.
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 enables the cost-effective and efficient production of RGB LEDs with improved efficiency and reduced defects, while also allowing for the fabrication of high-performance transistors on glass substrates at lower temperatures, enhancing the reliability and performance of both LED and display technologies.
Implementation Method 1
bonding structure, wherein said bonding structure comprises oxide to oxide bonding
Implementation Method 2
laser lift-off
Implementation Method 3
ion-cut
Data Source
AI summary
A 3D micro display, the 3D micro display including: a first level including a first single crystal layer, the first single crystal layer includes a plurality of LED driving circuits; a second level including a first plurality of light emitting diodes (LEDs), where the second level is disposed on top of the first level, where the second level includes at least ten individual first LED pixels; and a bonding structure, where the second level includes a plurality of bond pads, where the bonding structure includes oxide to oxide bonding.