Silicon Nitride Coating for Scratch Resistance and Optical Transparency
Solution Overview
Problem
Current coating materials for transparent substrates in consumer electronics and other applications lack durability, scratch resistance, and optimal optical properties, particularly when formed using physical vapor deposition methods, which often result in inferior hardness and optical band gap values.
Innovation Solution
A silicon-based coating material with specific compositions, including silicon, aluminum, nitrogen, oxygen, hydrogen, carbon, boron, and fluorine, is developed using chemical vapor deposition methods, achieving high hardness and a wide optical band gap, and is characterized by a Berkovich Indenter Hardness Test and optical properties such as high transmittance and low reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If physical vapor deposition (PVD) methods are used to form aluminum-based coatings, then high hardness and optical transparency are achieved, but processing limitations and inferior optical band gap values occur
Solution Approach 1:
The patent changes the deposition method from PVD to CVD/PECVD, altering the physical and chemical parameters of the coating process. This results in coatings with hardness of 22-35 GPa and optical band gap of 3.5-5.5 eV, simultaneously improving both mechanical strength and optical reliability
Solution Approach 2:
The patent uses composite material compositions including silicon, aluminum, nitrogen, oxygen, and hydrogen in specific ratios. This composite approach enables the coating to achieve both high hardness through strong Si-N and Al-N bonds and wide optical band gap through controlled stoichiometry and phase composition
2Strength
If sputtered silicon-based materials are used, then high density and hardness are achieved, but long deposition times and inferior optical properties occur
Solution Approach 1:
The patent replaces the mechanical sputtering process with chemical vapor deposition or plasma-enhanced chemical vapor deposition. This substitution uses chemical reactions and plasma activation to deposit materials, significantly reducing deposition time while maintaining or improving coating hardness through controlled stoichiometry and reduced defects
3Strength
If hydrogen-free SiNx coatings are used, then high hardness is achieved, but poor optical transparency and colorlessness occur
Solution Approach 1:
The patent optimizes the hydrogen content parameter within a specific range (1-30 atomic %) rather than completely eliminating it. This controlled hydrogen incorporation passulates dangling bonds and reduces absorption centers, improving optical transparency and colorlessness while maintaining high hardness through optimized Si-N bond density and stoichiometry
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 coating material exhibits enhanced hardness, optical transparency, and color stability, providing improved scratch resistance and optical performance, including high transmittance and low reflectance, while maintaining low stress and absorption, thus addressing the limitations of existing materials.
Implementation Method 1
forming durable and/or scratch resistant materials by chemical vapor deposition (CVD), which includes plasma enhanced chemical vapor deposition (PECVD)
Implementation Method 2
forming durable and/or scratch resistant materials by chemical vapor deposition (CVD), which includes plasma enhanced chemical vapor deposition (PECVD)
Data Source
AI summary
Embodiments of this disclosure pertain to a coating material comprising silicon and/or aluminum, hydrogen and any two or more of oxygen, nitrogen, carbon, and fluorine. The coating material exhibits a hardness of about 17 GPa or greater and an optical band gap of about 3.5 eV or greater. In some embodiments, the coating material includes, in atomic %, silicon and/or aluminum in an amount of about 40 or greater, hydrogen in an amount in the range from about 1 to about 25, nitrogen in an amount of about 30 or greater, oxygen in an amount in the range from about 0 to about 7.5, and carbon in an amount in the range from about 0 to about 10. The coating material may optionally include fluorine and/or boron. Articles including the coating material are also described and exhibit an average transmittance of about 85% or greater over an optical wavelength regime in the range from about 380 nm to about 720 nm and colorlessness.