Patterned Epitaxial Substrate for LED Warpage Control
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Solution Overview
Problem
The warpage of the edge in epitaxial substrates during the heating process, which leads to a decrease in yield in subsequent manufacturing processes due to thermal expansion coefficient and lattice mismatch issues in micro light-emitting diode (LED) manufacturing.
Innovation Solution
A patterned epitaxial substrate with distinct zones and varying pattern sizes, where the patterns and substrate are integrally formed, with different orthogonal projection areas, vertical heights, and pitches, preventing warpage by dispersing stress and improving epitaxial growth efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an epitaxial structure is grown on a substrate, then photoelectric devices can be manufactured, but thermal expansion coefficient mismatch and lattice mismatch cause uneven stress distribution leading to substrate warpage and decreased manufacturing yield
Solution Approach 1:
The substrate surface is segmented into multiple zones with different pattern densities. The first zone has a first pattern density and the second zone has a second pattern density different from the first. This segmentation allows different regions to compensate for stress differently, preventing overall substrate warpage while maintaining manufacturing yield.
Solution Approach 2:
Different regions of the substrate are given different local properties through varying pattern densities. The first zone and second zone have distinct pattern densities tailored to their specific stress compensation needs. This local quality approach enables precise control over stress distribution across the substrate surface, eliminating warpage without compromising the reliability of device manufacturing.
2Ease of manufacture
If uniform patterns are used across the substrate, then manufacturing process is simple, but stress cannot be evenly distributed leading to edge warpage
Solution Approach 1:
The substrate is divided into at least two zones with different pattern densities. This segmentation strategy maintains manufacturing simplicity by using the same fabrication process across the entire substrate, while the varying pattern densities in different zones effectively distribute stress and prevent edge warpage.
Solution Approach 2:
Local quality is achieved by varying the pattern density in different zones of the substrate. The first zone has a first pattern density and the second zone has a second pattern density, allowing each region to address its specific stress requirements. This approach prevents edge warpage while keeping the overall manufacturing process simple and consistent.
3Productivity
If the entire substrate is used for device fabrication, then substrate utilization is maximized, but stress concentration at edges causes warpage and reduces yield
Solution Approach 1:
The substrate is configured with different pattern densities in different zones to address stress distribution while maintaining high utilization. The first zone and second zone have distinct pattern densities that optimize stress compensation in each region, preventing warpage and ensuring high manufacturing yield across the entire substrate surface.
Solution Approach 2:
Segmentation of the substrate into zones with different pattern densities allows the entire substrate to be utilized for device fabrication while preventing stress concentration. By distributing patterns non-uniformly across zones, the substrate maintains structural integrity and high yield throughout the fabrication process.
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 design effectively prevents substrate warpage and enhances the yield of subsequent manufacturing processes, achieving good photoelectric properties and reliability in semiconductor structures.
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, stress unevenness, thus causing warpage of the edge of the epitaxial substrate
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 is disposed around a center of the substrate. 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.