Thin Film Encapsulation Masking Layer for Narrow Bezel OLED
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Solution Overview
Problem
Conventional thin film encapsulation technologies for flexible OLED devices face challenges in achieving a narrow bezel due to the shadow phenomenon during vacuum coating, which results in an increased non-display area and difficulties in achieving a narrow bezel.
Innovation Solution
A thin film encapsulation method and structure that includes a first barrier layer, an organic layer, and a second barrier layer, with a masking layer having a smaller etching rate than the second barrier layer, allowing for precise etching and minimizing the non-display area by overlapping the orthographic projections of these layers, thereby reducing the bezel width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vacuum coating with mask plate is used for encapsulation, then encapsulation coverage is improved, but shadow phenomenon increases causing larger non-display area
Solution Approach 1:
The encapsulation structure is divided into multiple thin film layers (first barrier layer, organic layer, second barrier layer, masking layer) with distinct functions. Each layer is deposited separately with precise thickness control, eliminating the shadow effect that occurs when using a single thick encapsulation layer with mask plate vacuum coating.
Solution Approach 2:
The invention transitions from planar mask plate deposition to multi-layer thin film stacking in the vertical dimension. By controlling the orthographic projections of each layer to overlap on the substrate, the encapsulation achieves precise lateral definition without the shadow phenomenon that plagues conventional mask-based vacuum coating.
2Reliability
If mask plate vacuum coating is used, then encapsulation is achieved, but bezel width increases
Solution Approach 1:
Each thin film layer is engineered with specific local properties: barrier layers provide moisture/oxygen blocking, the organic layer provides flexibility and stress relief, and the masking layer provides etching resistance. The varying thicknesses and material compositions of different layers optimize both encapsulation performance and bezel width reduction.
Solution Approach 2:
The encapsulation structure uses composite materials including inorganic barrier layers (silicon nitride, silicon oxide, silicon oxynitride) and organic materials, combining the advantages of each material type to achieve both effective encapsulation and narrow bezel width.
3Measurement precision
If masking layer with smaller etching rate is used, then etching precision is improved, but process complexity increases
Solution Approach 1:
The masking layer is designed with specific parameter optimizations: thickness of no greater than 100 nm (smaller than the 0.1-1 μm barrier layers) and material selection from metal oxides with controlled etching rates. These parameter changes enable precise etching definition while maintaining process feasibility through standard thin film deposition and etching techniques.
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 method effectively reduces the non-display area and achieves a narrower bezel by controlling the etching process and layer thicknesses, enhancing the encapsulation efficiency and flexibility of the OLED devices.
Implementation Method 1
a material of the masking layer has a smaller etching rate than a material of the second barrier layer
Implementation Method 2
a first barrier layer encapsulating a to-be-encapsulated object on a substrate; an organic layer on a side of the first barrier layer distal to the substrate; a second barrier layer encapsulating the organic layer
Data Source
AI summary
A thin film encapsulation structure includes a first barrier layer encapsulating a to-be-encapsulated structure on a substrate; an organic layer on the first barrier layer; a second barrier layer encapsulating the organic layer; a masking layer on the second barrier layer, orthographic projections of the second barrier layer, the first barrier layer and the masking layer on the substrate substantially overlap with each other, and a material of the masking layer has a smaller etching rate than a material of the second barrier layer.