Active Matrix Substrate with Oxidized Silicon Nitride Dielectric
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Solution Overview
Problem
In active matrix electrowetting on dielectric (AM-EWOD) devices, the use of SOG-derived insulating films affects TFT characteristics, while silicon nitride films provide high dielectric constant but poor adhesion with fluororesin layers, and silicon oxide films offer improved adhesion but increase driving voltage.
Innovation Solution
A method involving the formation of a silicon nitride film by plasma CVD, followed by surface oxidation to create a region with a high oxygen concentration, enhancing adhesion with fluororesin layers without increasing driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon nitride film is used as the dielectric layer, then the dielectric constant is high and driving voltage is reduced, but the adhesion with fluororesin water-repellent layer is insufficient causing interlayer peeling
Solution Approach 1:
The patent applies local quality by creating a dual-layer dielectric structure where the lower layer (silicon nitride) provides high dielectric constant for low driving voltage, while the upper layer (silicon oxide) provides excellent adhesion with the fluororesin water-repellent layer. Each layer performs its specific function locally, resolving the contradiction between adhesion and dielectric performance.
Solution Approach 2:
The patent uses composite materials by combining silicon nitride and silicon oxide in a layered dielectric structure. This composite approach allows the system to simultaneously achieve the high dielectric constant of silicon nitride and the superior adhesion properties of silicon oxide, eliminating the need to choose between the two materials.
2Reliability
If a silicon oxide film is used as the dielectric layer, then the adhesion with fluororesin is improved, but the dielectric constant is low increasing the driving voltage
Solution Approach 1:
The patent applies local quality by creating a dual-layer dielectric structure where the lower layer (silicon nitride) provides high dielectric constant for low driving voltage, while the upper layer (silicon oxide) provides excellent adhesion with the fluororesin water-repellent layer. Each layer performs its specific function locally, resolving the contradiction between adhesion and dielectric performance.
Solution Approach 2:
The patent uses composite materials by combining silicon nitride and silicon oxide in a layered dielectric structure. This composite approach allows the system to simultaneously achieve the high dielectric constant of silicon nitride and the superior adhesion properties of silicon oxide, eliminating the need to choose between the two materials.
3Reliability
If an SOG-derived insulating film is used, then the insulation strength is supplemented, but the firing process affects TFT characteristics
Solution Approach 1:
The patent extracts the problematic firing step from the manufacturing process by replacing SOG-derived insulating films with plasma CVD-formed silicon nitride films. This extraction eliminates the thermal damage to TFT characteristics while maintaining the necessary insulation strength through the alternative dielectric material.
Solution Approach 2:
The patent replaces the temperature-sensitive SOG process with a plasma CVD process that forms silicon nitride films at lower temperatures. This substitution uses a more stable, less transient process that doesn't require high-temperature firing, thereby protecting the TFT characteristics from degradation.
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 approach reduces driving voltage and improves adhesion between the dielectric and water-repellent layers, preventing peeling and ensuring high yield in manufacturing microfluidic devices.
Implementation Method 1
a dielectric layer including a silicon nitride film formed by a plasma CVD method
Implementation Method 2
the silicon nitride film has a surface layer region containing oxygen in the surface on the side in contact with the water-repellent layer
Implementation Method 3
electrowetting (EW) that manipulates a droplet by means of application of an electric field
Data Source
AI summary
Provided are an active matrix substrate having a reduced driving voltage and excellent adhesion between a dielectric layer and a water-repellent layer and a microfluidic device including the substrate. The active matrix substrate includes an array electrode, a dielectric layer covering the array electrode, and a first water-repellent layer in this order on a first substrate. The dielectric layer includes a silicon nitride film located on the side in contact with the first water-repellent layer, and the silicon nitride film has a surface layer region containing oxygen in the surface on the side in contact with the first water-repellent layer.