Segmented Buffer Layers for Flexible Substrates
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Solution Overview
Problem
Flexible display devices face deterioration due to oxygen and moisture permeation, which creates cracks in silicon nitride layers, compromising the effectiveness of buffer layers and potentially leading to operation failure.
Innovation Solution
A flexible substrate design featuring multiple buffer layers with patterned segments and contact holes to reduce crack occurrence and block moisture permeation, using silicon nitride and silicon oxide layers alternately stacked with patterned segments to connect and block permeation paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If silicon nitride layers are used in buffer layers to suppress oxygen and moisture permeation, then oxygen and moisture permeation is reduced, but cracks are likely to occur in the silicon nitride layers due to low flexibility
Solution Approach 1:
The first buffer layer is patterned to include a plurality of first buffer segments instead of a continuous layer. This segmentation reduces the flexibility stress concentration in silicon nitride layers, preventing crack propagation while maintaining the barrier function against oxygen and moisture permeation.
Solution Approach 2:
Different regions of the buffer layer structure are assigned different materials and configurations. The first buffer layer uses segmented silicon nitride for crack prevention, while the second buffer layer uses silicon oxide with contact holes for moisture blocking. This local differentiation optimizes both crack resistance and permeation suppression in respective regions.
2Reliability
If silicon oxide layers are used in buffer layers to improve flexibility, then flexibility is improved, but oxygen and moisture permeation increases due to vulnerability of silicon oxide layers
Solution Approach 1:
The buffer layer structure employs a composite of silicon nitride and silicon oxide layers with different properties. The silicon nitride segments provide crack resistance and baseline barrier function, while the silicon oxide layers provide flexibility enhancement. Together they create a composite structure that achieves both flexibility improvement and maintained permeation suppression.
Solution Approach 2:
The second buffer layer of silicon oxide acts as an intermediary between the segmented first buffer layer and the third buffer layer. It provides a flexible transition zone that blocks moisture permeation paths from the substrate, mediating between the rigid segmented structure below and the protective third layer above.
3Reliability
If the first buffer layer is patterned to include multiple buffer segments to reduce cracks, then crack occurrence is reduced, but moisture permeation paths may be created between segments
Solution Approach 1:
The second buffer layer is positioned to cover and connect the gaps between the segmented first buffer layer. This nested arrangement where the second layer envelops the segment boundaries creates a continuous moisture barrier that blocks permeation paths between segments while preserving the crack-reducing segmentation of the first layer.
Data Source
AI summary
A flexible substrate and corresponding method of manufacturing are described. The flexible substrate includes a substrate, a first buffer layer, a second buffer layer and a third buffer layer. The first buffer layer, positioned on the substrate, has a plurality of first buffer segments. The second buffer layer, positioned on the first buffer layer, has a plurality of second buffer segments. The third buffer layer, positioned on the second buffer layer, is connected to the first buffer layer via a contact hole between two adjacent second buffer segments. Because the first buffer layer is patterned to include buffer segments, cracking in the first buffer layer is reduced. Because the third buffer layer is connected to segments of the first buffer layer via a contact hole between two adjacent second buffer segments, moisture permeation paths from the substrate into the second buffer layer are blocked, suppressing moisture permeation.