3D Micro Display Device with Oxide-to-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 face challenges with high temperature processing and yield issues.
Innovation Solution
The use of ion-cut technology and smart layer transfer techniques, such as oxide-to-oxide bonding and laser lift-off, to stack red, green, and blue LEDs, allowing for lower temperature processing and reducing thermal expansion coefficient mismatches, along with the integration of control circuits and image sensors on silicon sub-mounts for improved light output and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional 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 invention 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 temperature processing that causes thermal expansion mismatches and defects in traditional methods.
Solution Approach 2:
The invention changes the bonding parameter from high-temperature processing to low-temperature oxide-to-oxide bonding. By using oxide barrier layers and bonding at reduced temperatures, the process accommodates thermal expansion coefficient differences between materials, significantly reducing defects while maintaining bonding integrity.
2Manufacturing precision
If traditional layer transfer techniques are used for displays, then thin monocrystalline films can be deposited, but high temperature processing and yield issues occur
Solution Approach 1:
The display structure is segmented into multiple functional layers (active matrix layer, light-emitting layer, color conversion layer) that are fabricated separately and bonded together using low-temperature oxide-to-oxide bonding. This approach maintains the quality of thin monocrystalline films while avoiding high temperature processing that reduces yield.
Solution Approach 2:
Oxide barrier layers are introduced as intermediary bonding surfaces between different monocrystalline layers. These oxide layers enable low-temperature bonding while maintaining the integrity of the thin monocrystalline films, thus improving yield without sacrificing manufacturing precision.
3Temperature
If red, green, and blue LEDs are stacked using ion-cut technology, then lower temperature processing is achieved, but complex bonding structures are required
Solution Approach 1:
The invention changes the bonding interface to oxide-to-oxide bonding, which enables low-temperature processing. The oxide barrier layers are deposited on each LED layer and provide a standardized bonding surface, simplifying the overall process despite the stacked configuration.
Solution Approach 2:
The oxide barrier layers serve multiple functions: they act as bonding surfaces for low-temperature oxide-to-oxide bonding, provide thermal expansion mismatch accommodation, and serve as diffusion barriers. This multi-functionality reduces the need for additional complex bonding structures.
4Productivity
If control circuits and image sensors are integrated on silicon sub-mounts, then light output and efficiency improve, but manufacturing complexity increases
Solution Approach 1:
The invention merges the control circuits and image sensors with the LED layers on a common silicon sub-mount. This integration improves light output efficiency by reducing electrical interconnect losses and enabling precise pixel-level control, while the standardized oxide bonding process manages the manufacturing complexity.
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 production of efficient RGB LEDs with reduced defects and improved light output by minimizing thermal expansion issues and integrating control circuits for enhanced color stability and tunability, while also allowing for the construction of transistors on glass substrates at lower temperatures, improving display technology.
Implementation Method 1
bonding structure, wherein said bonding structure comprises oxide to oxide bonding
Implementation Method 2
laser lift-off, to stack red, green, and blue LEDs
Implementation Method 3
ion-cut technology and smart layer transfer techniques
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), the first plurality of LEDs including a second single crystal layer; a third level including a second plurality of light emitting diodes (LEDs), the second plurality of LEDs including a third single crystal layer, where the first level is disposed on top of the second level, where the second level includes at least ten individual first LED pixels; and a bonding structure, where the bonding structure includes oxide to oxide bonding.