Display Pixel Circuit Barrier Layer for Stable Laser Crystallization
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Solution Overview
Problem
The uniformity of crystallized polysilicon in semiconductor layers formed by laser crystallization processes is compromised due to diffusion of unwanted species or contaminants from substrates, particularly when using transparent polyimide substrates, leading to instability in display apparatus manufacturing.
Innovation Solution
A display apparatus design incorporating a barrier layer with a density ranging from 2 g/cm3 to 6 g/cm3, made from materials like silicon nitride, aluminum oxide, or zirconium oxide, is placed between the substrate and semiconductor layers to prevent hydrogen emission from the substrate, allowing for stable laser crystallization and enhancing product reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a transparent polyimide substrate is used to reduce weight and improve flexibility, then the display apparatus achieves lighter weight and better flexibility, but hydrogen emissions from the substrate contaminate the semiconductor layer during laser crystallization, reducing crystallization uniformity and product reliability
Solution Approach 1:
An aluminum oxide barrier layer is introduced as an intermediary between the transparent polyimide substrate and the semiconductor layer. This barrier layer specifically blocks hydrogen emissions from the substrate during laser crystallization, preventing contamination of the semiconductor layer while allowing the substrate's lightweight and flexible properties to be maintained.
Solution Approach 2:
The patent uses a composite structure combining transparent polyimide substrate with aluminum oxide barrier layer. This composite approach allows the system to simultaneously achieve the lightweight and flexible characteristics of polyimide while incorporating the hydrogen-blocking properties of aluminum oxide, resolving the contradiction between substrate benefits and crystallization quality.
2Ease of manufacture
If a traditional barrier layer structure is used without optimized density, then the manufacturing process is simpler, but the barrier layer fails to effectively block hydrogen emissions, leading to contaminated semiconductor layers and reduced product reliability
Solution Approach 1:
The patent specifies optimizing the barrier layer density to a range of 2.0-6.0 g/cm³ and thickness to 200-600 Å. These parameter optimizations ensure the barrier layer achieves effective hydrogen blocking capability while maintaining manufacturability through standard deposition processes.
3Reliability
If the barrier layer thickness is increased to improve hydrogen blocking, then hydrogen emission prevention is enhanced, but the manufacturing complexity and process difficulty increase
Solution Approach 1:
The patent defines an optimal thickness range of 200-600 Å for the barrier layer. This parameter optimization achieves effective hydrogen blocking without excessive thickness, balancing protection efficiency with manufacturing simplicity and avoiding unnecessary process complexity.
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 barrier layer effectively blocks hydrogen emissions from the substrate, ensuring stable crystallization of semiconductor layers and improving the reliability and uniformity of the display apparatus, even when using substrates with transparent polyimide.
Implementation Method 1
a barrier layer located between the first substrate and the buffer layer, including one material from among silicon nitride (SiNx), aluminum oxide (Al2O3), and zirconium oxide (Zr2O3), and having a density ranging from about 2 g/cm3 to about 6 g/cm3
Implementation Method 2
a semiconductor layer of the display apparatus may be formed by a laser crystallization process that crystallizes amorphous silicon into polysilicon
Data Source
AI summary
A display apparatus includes a first substrate, a main pixel circuit located on the first substrate and including a first semiconductor layer, an auxiliary pixel circuit located on the first substrate and including a second semiconductor layer, a buffer layer located between the first substrate and the first semiconductor layer and between the first substrate and the second semiconductor layer, and a barrier layer located between the first substrate and the buffer layer, including one material from among silicon nitride (SiNx), aluminum oxide (Al2O3), and zirconium oxide (Zr2O3), and having a density ranging from about 2 g/cm3 to about 6 g/cm3.