Micro-Transfer Printed LED Arrays Orientation Uniformity
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Solution Overview
Problem
Variations in materials and photolithographic processes on native source wafers lead to operational non-uniformities in micro-transfer-printed components on destination substrates, resulting in inconsistent performance and attributes of micro-components.
Innovation Solution
The method involves micro-transfer printing components from a source wafer to a destination substrate using a stamp, where components are arranged in different orientations, such as rotated, offset, or interlaced, to mitigate large-scale non-uniformity by systematically varying their spatial arrangement and attributes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If components are transferred from a native source wafer using conventional micro-transfer printing, then components can be assembled on the destination substrate, but operational non-uniformities and performance variability occur due to material and process variations on the source wafer
Solution Approach 1:
The destination substrate is divided into multiple arrays, with each array receiving components from a specific region of the source wafer. This segmentation allows different arrays to be optimized for different performance characteristics, mitigating the impact of source wafer variations across the entire substrate.
Solution Approach 2:
Different arrays on the destination substrate are assigned different orientations and component arrangements tailored to their specific locations. This local optimization compensates for spatial variations in the source wafer, ensuring each region achieves its target performance characteristics.
2Device complexity
If components are arranged in a single uniform orientation on the destination substrate, then the transfer process is simplified, but large-scale non-uniformity and objectionable patterns like pattern noise appear
Solution Approach 1:
Adjacent arrays on the destination substrate are assigned different orientations (e.g., alternating between 0° and 90°). This asymmetric arrangement breaks up large-scale non-uniform patterns and reduces visible pattern noise while maintaining manufacturing feasibility.
Solution Approach 2:
The component arrangement extends into the orientation dimension, with arrays rotated at different angles relative to each other. This adds a new degree of freedom to the arrangement, enabling uniformity improvement without increasing process complexity.
3Quantity of substance
If components from different locations on the source wafer are transferred to the same region on the destination substrate, then component density is increased, but performance variability is amplified
Solution Approach 1:
The destination substrate is divided into multiple arrays, with each array receiving components from a specific region of the source wafer. This segmentation allows different arrays to be optimized for different performance characteristics, mitigating the impact of source wafer variations across the entire substrate.
Data Source
AI summary
A method of micro-transfer printing comprises providing a component source wafer and components disposed in, on, or over the component source wafer. A destination substrate and a stamp for transferring the components from the component source wafer to the destination substrate is provided. The component source wafer has an attribute or structure that varies across the component source wafer that affects the structure, operation, appearance, or performance of the components. A first array of components is transferred from the component source wafer to the destination substrate with a first orientation. A second array of components is transferred from the component source wafer to the destination substrate with a second orientation different from the first orientation. Components can be transferred by micro-transfer printing and different orientations can be a different rotation, overlap, interlacing, or offset.