Thin films and their applications (Episode 1)

In this episode, we are getting to know about thin films and how they are made.

What is a thin film?

Thin film is a layer of material on some surface similar to the candy coating of an m&m except it’s much thinner.

The thin film can be anywhere between nanometers to micrometers interms of thickness

In many practices the thin film applied to the surface will consist of many different materials deposited in sequential order

For certain applications, there may be different names for the substate such as a wafer for semiconductor industries

The thin film is deposited differently depending on the application but there are somethings that all applications have in common. The material you want to deposit onto the substrate always starts in some initial location. Depending on the application this may be referred to as a source, a target or something different. You may also have a substrate that you want to coat and that substrate in some type of a container where the coating would take place and that can be referred to as a chamber.

In all applications, the desired material has to travel some distance and then become deposited onto the substrate through either a physical or chemical change. In this example we physically heat up the source until the material in the source either evaporates or sublimes. The newly gaseous material that expands to coat all of the cooled surfaces in the chamber. And then after the deposition is complete, you can see that a thin film has been deposited on both the substrate and the QCM

QCM – Quartz Crystal Microbalance

In these applications, QCM is an effective tool for measuring thin film thickness as a deposition takes place. This is known as an in-situ measurement and a QCM is able to provide in-situ measurements of a thin film because the QCM sensor and the substrate are both coated by the source material at the same time. By using the QCM, you are able to ensure that the thin film will be the same thickness for all substrates used in production. This improves the production yield and the overall quality of the coatings compared to measuring thickness after the deposition taken place which that method would be known as some kind of an execute measurement.

QCM systems are commonly used in PVD and CVD chambers in order to deposit thin films on key components used in final products you may be familiar with.

Let’t take a look at some different ways to deposit a thin film

1/ PVD – Physical Vapor Deposition

In PVD process, desired materials are heated by a filament and evaporate then deposited on the substrate.

Explore different thin film applications

Resistive Heating
Electron Beam
Sputtering
Molecular Beam Epitaxy

2/ CVD – Chemical Vapor Deposition

Moving away from PVD applications, we take a look at chemical vapor deposition or CVD. CVD goes about depositing the desired material onto the substrate through chemical reactions instead of physical changes.