Multi-Layer Lens Structure Suppresses Substrate Warpage
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Solution Overview
Problem
The existing manufacturing methods for electro-optical devices, such as liquid crystal displays, face challenges in suppressing substrate warpage caused by residual stress in lens material layers, which can lead to planarization treatment failures and damage to wiring layers during annealing processes.
Innovation Solution
A manufacturing method involving the formation of a lens layer composed of multiple layers with different materials, where a first transmissive layer and a sacrificial layer are polished and etched to form a thin, stress-reduced structure, avoiding the need for annealing and minimizing warpage, and ensuring the lens layer is formed between the insulating layer and the pixel electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a lens material layer is formed by filling a concave surface with a silicon oxynitride film, then the lens layer is formed between the switching element and the pixel electrode, but residual stress in the lens material layer causes substrate warpage
Solution Approach 1:
The lens material layer is divided into multiple layers (first lens material layer and second lens material layer) with different materials and refractive indices. This segmentation allows each layer to contribute differently to the overall lens function while distributing and reducing residual stress, thereby preventing substrate warpage.
Solution Approach 2:
The patent uses composite materials by forming the lens layer with multiple materials (silicon oxynitride and other transparent materials) having different optical and mechanical properties. This composite structure enables both the desired lens optical characteristics and reduced residual stress through material property differentiation.
2Shape
If an annealing process is performed to mitigate substrate warpage, then the warpage is reduced, but the wiring and switching elements at lower layers may be damaged
Solution Approach 1:
Instead of using high-temperature annealing that could damage lower layers, the patent converts the harmful residual stress into a beneficial outcome by using multiple low-refractive-index materials in the lens layer. This approach reduces stress without requiring damaging thermal processing, thus protecting the wiring and switching elements.
3Shape
If an annealing process is performed to mitigate substrate warpage, then the warpage is reduced, but the film quality of various types of layers may be adversely affected
Solution Approach 1:
The patent eliminates the need for annealing by using multiple lens material layers with different materials. This converts the problematic high-temperature process into a beneficial low-stress multi-layer structure that preserves film quality while achieving substrate flatness.
4Device complexity
If a single-layer lens structure is used, then the manufacturing process is simpler, but residual stress causes substrate warpage and planarization treatment failures
Solution Approach 1:
The single lens layer is segmented into multiple sub-layers (first and second lens material layers) with different materials. This segmentation reduces residual stress in each individual layer, preventing the cumulative stress that causes warpage and planarization failures in single-layer structures.
Solution Approach 2:
The patent adds a dimensional aspect by creating a multi-layer vertical structure instead of a single horizontal layer. This vertical dimensioning allows stress distribution across multiple interfaces and materials, improving planarization treatment success while maintaining manufacturing feasibility.
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
This method effectively suppresses substrate warpage and prevents planarization treatment failures, maintaining the integrity of the wiring layers and enhancing the reliability of the electro-optical device by using a multi-layer lens structure with reduced residual stress.
Implementation Method 1
removing the sacrificial layer residual portion by etching
Implementation Method 2
polishing the first transmissive layer and the first sacrificial layer to form a first layer
Data Source
AI summary
A manufacturing method of a lens layer, including a first layer and a second layer for an electro-optical device, includes forming a first transmissive layer at a concave surface of an translucency insulating layer, forming, with a different material from the first transmissive layer, a first sacrificial layer on first transmissive layer, polishing its surface, to form a first layer being a residual portion of the first transmissive layer and a sacrificial layer residual portion being a residual portion of the first sacrificial layer, removing the sacrificial layer residual portion, forming a second transmissive layer at the first layer, forming, using a different material from the second transmissive layer, a second sacrificial layer on the second transmissive layer, and polishing the second transmissive layer and the second sacrificial layer to form a second layer from the second transmissive layer.