Protective Layer Roughness Layout for Uniform Display Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display devices face challenges in reducing stains and thickness distribution of protective films, which affect processibility.
Innovation Solution
A display device design featuring a second protective layer with higher surface roughness and lower thickness than the first protective layer, composed of silicon oxide or silicon oxynitride, and a via layer with greater thickness than the first protective layer, along with specific manufacturing methods including inkjet printing and etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a protective film is formed on a smooth protective layer, then the protective film may have poor adhesion and uniformity, but if the protective layer surface is made rough, then the protective film adhesion and uniformity improve
Solution Approach 1:
The patent applies different surface roughness characteristics to different layers: the first protective layer (SiNx) has a smooth surface (Ra ≤ 1 nm) for initial planarity, while the second protective layer (SiOx or SiOxNy) has a controlled rough surface (Ra > 1 nm) specifically at its top surface to improve protective film adhesion and uniformity. This local differentiation of surface quality resolves the contradiction between smoothness and film formation quality.
Solution Approach 2:
The patent changes the surface roughness parameter of the second protective layer by controlling its material composition (SiOx or SiOxNy) and deposition conditions to achieve Ra > 1 nm. This parameter change enables better protective film formation without compromising the underlying smooth structure, thus resolving the contradiction between surface smoothness and film uniformity.
2Reliability
If the first protective layer is made thicker to provide better protection, then the via layer thickness must be increased accordingly, but this increases the overall device thickness and complexity
Solution Approach 1:
The patent divides the protective layer into two distinct segments: a first protective layer (SiNx) with thickness of 300-500 nm providing base protection, and a second protective layer (SiOx or SiOxNy) with thickness of 50-200 nm providing enhanced protection and surface functionality. This segmentation allows each layer to be optimized independently, reducing the need for excessive thickness in any single layer while maintaining overall protection capability.
Solution Approach 2:
The patent uses a composite structure of SiNx and SiOx/SiOxNy layers with different material properties. The SiNx layer provides mechanical strength and baseline protection, while the SiOx/SiOxNy layer adds chemical stability and controlled surface roughness. This composite approach achieves superior protection with optimized thickness distribution, avoiding the need for uniformly thick layers that would increase device complexity.
Data Source
AI summary
The display device includes light emitting elements disposed on a first surface of a substrate, a connection electrode disposed on a second surface of the substrate, a first protective layer disposed on the connection electrode, and a second protective layer disposed on the first protective layer. A surface roughness of the second protective layer is greater than a surface roughness of the first protective layer.