Patterned Epitaxial Substrate Warpage Prevention
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Solution Overview
Problem
The warpage of epitaxial substrates during the heating process due to thermal expansion coefficient and lattice mismatch issues leads to decreased yield in manufacturing processes for micro light-emitting diodes (LEDs).
Innovation Solution
A patterned epitaxial substrate with concentric zones and varying pattern sizes, shapes, and pitches is designed, where the patterns and substrate are integrally formed, preventing edge warpage by dispersing stresses and improving epitaxial growth quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional epitaxial substrate is used during heating, then the epitaxial growth can be performed, but thermal expansion coefficient mismatch and lattice mismatch cause uneven stress distribution leading to edge warpage
Solution Approach 1:
The substrate is divided into multiple zones (first zone, second zone, third zone) with different pattern densities and configurations. The first zone has higher pattern density than the second zone, creating a gradient structure that distributes thermal stress non-uniformly across the substrate surface, preventing edge warpage while maintaining overall substrate stability during heating.
Solution Approach 2:
Different regions of the substrate are given different local properties through varying pattern densities and configurations. The first zone (central region) has higher pattern density to provide structural support and stress distribution, while the second zone (edge region) has lower pattern density to accommodate thermal expansion, creating local quality variations that prevent warpage.
2Area of stationary object
If the substrate area is increased to accommodate larger epitaxial structures, then more devices can be manufactured, but stress unevenness and warpage increase
Solution Approach 1:
The large substrate area is segmented into multiple concentric zones with progressively varying pattern densities. This segmentation allows the substrate to maintain large area for device manufacturing while distributing stress uniformly through the gradient pattern structure, preventing warpage even at the edges.
Solution Approach 2:
The pattern density parameter is changed across different zones of the substrate. The first zone has higher pattern density while the second zone has lower pattern density, creating a parameter gradient that accommodates thermal expansion across the large substrate area, maintaining stress uniformity and preventing warpage.
3Manufacturing precision
If pattern density is increased to improve epitaxial growth quality, then better device performance is achieved, but stress concentration increases leading to warpage
Solution Approach 1:
High pattern density is applied locally in the first zone where epitaxial growth quality is most critical, while the second zone has reduced pattern density to minimize stress concentration. This local quality differentiation allows high-quality epitaxial growth in the central region without causing excessive stress concentration and warpage at the edges.
Solution Approach 2:
The substrate is segmented into zones with different pattern densities, allowing the first zone to have high pattern density for improved epitaxial growth quality while the second zone has lower density to reduce stress concentration. The gradient transition between zones prevents abrupt stress changes that would cause warpage.
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
The solution effectively prevents substrate warpage, enhances manufacturing yield, and achieves good photoelectric properties and reliability in semiconductor structures, particularly in micro LEDs.
Implementation Method 1
The thermal temperature difference or the difference in the thermal expansion coefficient in a heating process and a lattice mismatch lead to uneven distribution of stresses
Data Source
AI summary
A patterned epitaxial substrate includes a substrate and a plurality of patterns. The substrate has a first zone and a second zone surrounding the first zone. The first zone and the second zone are disposed in a concentric manner. The patterns and the substrate are integrally formed, and the patterns are disposed on the substrate. The patterns include a plurality of first patterns and a plurality of second patterns. The first patterns are disposed in the first zone. The second patterns are disposed in the second zone. Sizes of the first patterns are different from sizes of the second patterns.