SPIN COATER

Spin coating is a technique used to apply liquid material onto a substrate and form a uniform thin film through high-speed rotation.
It is utilized in many fields, including semiconductors, optical devices, and biosensors, and is characterized by its capability for precise film thickness control.

In this method, the liquid is dropped onto the center of the substrate, and rotational motion is used to spread the thin film.
The centrifugal force from the rotation distributes the liquid uniformly, and the excess material spins off the substrate.
The film is formed as the solvent evaporates, resulting in a uniform coating.

The spreading behavior of the liquid and the uniformity of the film thickness depend on the rotation speed, time, liquid viscosity, and surface tension.
By setting appropriate parameters, it is possible to obtain thin films tailored to the application.

1.Liquid Dispensing

- The coating liquid is dispensed onto the center of the substrate.
- The dispensed amount is carefully adjusted as an inappropriate amount can lead to non-uniform film thickness.

2.Low-Speed Rotation (Spread Phase)
- The substrate is rotated at a low speed to uniformly spread the liquid across the surface.
- Speeds of a few hundred rpm are typical.

3.High-Speed Rotation (Spin-Off Phase)
- Rotation is switched to high speed to form the thin film.
- Excess liquid is ejected off the substrate, and the solvent evaporates.
- Rotation speeds of several thousand rpm are typical.

4.Drying/Curing
- The film cures as the solvent completely evaporates.
- Heating or UV exposure is applied as needed.

1.Rotation Speed
- Lower speeds tend to form thicker films, while higher speeds form thinner films.
- Film quality changes depending on whether the rotation is at a constant speed or varied in stages.

2.Time
- Longer rotation times result in a more uniform film.
- High-speed rotation for a short duration leads to rapid solvent drying.

3.Viscosity and Surface Tension
- Higher viscosity results in a thicker film, and lower viscosity yields a thin film.
- High surface tension makes it difficult for the liquid to spread uniformly.

4.Environmental Conditions
- Temperature and humidity affect film formation.
- Work in a cleanroom environment is often required.

-Semiconductor Manufacturing: Utilized for photoresist coating, which is essential in the process of forming fine patterns.

-Optical Thin Films: Used in the manufacturing of anti-reflection coatings and color filters

-Biosensors: Used for substrate coating to immobilize biomolecules.

-Energy Applications:Also used for forming the active layer of perovskite solar cells.

-High-Precision Film Thickness Control: Uniform thin films can be formed, allowing for thickness adjustment at the nanoscale.

-Simple Process: The equipment is relatively easy to operate, and the process has high reproducibility.

-Short Film Formation Time: Thin films can be created in seconds to tens of seconds, enabling efficient manufacturing.

Spin coating is an excellent technique that enables precise film thickness control in thin film formation.
By adjusting parameters according to the application and establishing an appropriate process, its utilization in various fields is highly anticipated.