Flip-Chip Micro-LED Mesa Structure for Higher Pixel Density
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing micro-LED devices face challenges in efficient manufacturing and light-emitting area maximization due to their small size and complex assembly processes, particularly in achieving high density and brightness for emerging display applications like wearable and large-area displays.
Innovation Solution
A thin film flip-chip (TFFC) design for micro-LEDs with a mesa structure that includes a p-contact layer contacting the p-type layer, a cathode contacting the n-type layer's sidewall, and an anode contacting the p-contact layer's top surface, with dielectric materials isolating these components to enhance light extraction and handling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional pick-and-place assembly is used for micro-LEDs, then individual LEDs can be assembled, but the assembly process becomes slow and error-prone as die size decreases
Solution Approach 1:
The patent merges multiple micro-LED dies into a single integrated structure grown on a common substrate. The semiconductor layers are formed as a unified component with shared substrate, eliminating the need for separate pick-and-place assembly of individual dies. This combining approach directly resolves the contradiction by enabling mass production without alignment errors.
Solution Approach 2:
The patent performs preliminary actions by pre-assembling multiple micro-LED dies on a common substrate during the epitaxial growth process itself. The dies are positioned and integrated before final device completion, allowing subsequent processing to treat them as a single unit. This preliminary integration eliminates later assembly steps and their associated precision problems.
2Quantity of substance
If micro-LED dimensions are reduced for high density displays, then pixel density increases, but light-emitting area decreases
Solution Approach 1:
The patent transitions from planar light emission to three-dimensional light emission by forming vertical sidewalls on the mesa structures. The light-emitting surface extends vertically along the sidewalls in addition to the top surface, effectively adding a vertical dimension to the light-emitting area. This allows smaller footprint devices to maintain or increase total light output area.
Solution Approach 2:
The patent implements nested structures by forming mesas with vertical sidewalls that contain additional light-emitting surfaces within the vertical profile. The light-emitting area is nested within the three-dimensional mesa structure, maximizing the use of available space within the device footprint while maintaining high pixel density.
3Power
If thin film flip-chip design is used, then forward voltage and current drive capability improve, but dimensional down-scaling becomes difficult
Solution Approach 1:
The patent changes the structural parameters of the flip-chip design by forming vertical sidewalls and three-dimensional mesa structures. This parameter change allows the device to maintain the electrical performance benefits of flip-chip architecture while enabling dimensional down-scaling through optimized vertical profiles and reduced footprint configurations.
Solution Approach 2:
The patent introduces dynamic adaptability by creating a modular mesa structure with vertical sidewalls that can be scaled in height and width independently. This dynamic structure allows the same flip-chip design to be adapted to various size requirements while maintaining electrical performance, making the design versatile across different device dimensions.
4Adaptability or versatility
If vertical thin film design is used, then dimensional down-scaling is easier, but forward voltage and brightness performance decrease
Solution Approach 1:
The patent merges the advantages of vertical thin film scalability with thin film flip-chip electrical performance by integrating vertical sidewall structures into the flip-chip architecture. The combined design achieves both easy dimensional down-scaling and high current drive capability, resolving the contradiction between scalability and brightness performance.
Data Source
AI summary
A micro-light emitting diode (uLED) device comprises: a mesa comprising: a plurality of semiconductor layers including an n-type layer, an active layer, and a p-type layer; a p-contact layer contacting the p-type layer; a cathode contacting the first sidewall of the n-type layer; a first region of dielectric material that insulates the p-contact layer, the active layer, and a first sidewall of the p-type layer from the cathode; an anode contacting the top surface of the p-contact layer; and a second region of dielectric material that insulates the active layer, a second sidewall of the p-type layer, and the second sidewall of the n-type layer from the anode. The top surface of the p-contact layer has a different planar orientation compared to the first and second sidewalls of the n-type layer. Methods of making and using the uLED devices are also provided.