One of the most common techniques in the coating world for applying ultra thin films to substrates is called spin coating. It is used in a great variety of industries and technology sectors. The biggest advantage of spin coating is that it ensures quick, easy extremely thin and very uniform films. It can be as thin as a few nano meters to a few microns.
Uniformity and thickness
In semiconductor industries the high uniformaty and thin films are required to make good products. It is also growing in popularity in the nanotechnology industry and organic electronics industry. The application possibilities vary greatly. A few examples are:
- Smart phones
- Nano materials
- Synthetic metals
- Organic semiconductors
Spin coating theory
Spin coating is bassicly the application of a very thin layer even on a surface while rotating.
- First the object is covered with a special ink that contains molecules that are dissolved through a solvent
- After that the object rotates at a fast speed ( 10 rotations per second) and most of the special ink flies off the side
- The air dries the film solvent that is left and a plasticized film is formed. When it’s completely dry only the molecules remain on the surface creating an ultra thin layer.
The centripetal force combined with the surface tension of the solution pulls the liquid coating into an even covering. During this time the solvent then evaporates to leave the desired material on the substrate in an even covering.
Advantages of Spin Coating in Vietnam
The biggest advantage of spin coating is its simplicity and the thin and even coating that is achieved by this process. Due to the ability to have high spin speeds the high airflow leads to fast drying times which in turn results in high consistency at both macroscopic and nano length scales.
The disadvantage of spin coating is that it is an inherently batch (single substrate) process and therefore relatively low throughput compared to roll-to-roll processes. The fast drying times can also lead to lower performance for some particular nano-technologies which require time to self-assemble and/or crystallise. Finally, the material usage is typically very low at around 10% or less with the rest being flung off the side and wasted. This is not usually an issue for research environments it is clearly wasteful for manufacturing.