When it comes to manufacturing thin films, there is a range of different methods that can be used. While some are specifically designed to be used in certain situations, there are many that can be useful in a wide variety of industries.
Two methods of sputtering that are commonly used are direct current (DC) sputtering and radio frequency (RF) sputtering.
They may sound similar, but there are many key differences that separate these two manufacturing methods, which we will discuss in this article.
What is DC sputtering?
Direct current (DC) sputtering is a technique that is used to manufacture thin-film technologies. This process uses an ionized gas molecule to vaporize (sputter) molecules off of one material and turn them into plasma.
This type of sputtering occurs within a vacuum chamber which contains a target material and a target substrate, between which the plasma will move.
You’ll most commonly see this technique being used in situations where electrically conductive target materials are used.
This is because it has a relatively low cost compared to other methods, and manufacturers are able to maintain a high level of control throughout the entire process.
What is RF sputtering?
On the other hand, radio frequency (RF) sputtering is another technique used to create thin films that work by alternating the electrical potential of a current within the vacuum chamber to avoid a charge building up during the manufacturing process.
During RF sputtering, an energetic wave is passed through an inert gas within the vacuum chamber to become ionized. Then, as these high-energy atoms are sputtering off as a fine spray, they will coat a target material with a thin film coating.
This process relies on the magnets that are placed behind the negative cathode, which stops electrons from being able to bombard the substrate material. The result of this is a much faster deposition rate.
How does RF sputtering compare to DC sputtering?
Although DC sputtering is preferred because of its low cost, which is always a benefit to manufacturers, it’s mainly only useful when working with metal target coatings that are electrically conductive – like gold. When it comes to other materials and metals, it may not always be the most desirable method. On the other hand, RF sputtering works well with dielectric materials – which are non-conducting, insulating materials.
The main difference that separates radio frequency sputtering and direct current sputtering is that they use different power sources. DC sputtering relies on a direct current to power the sputtering process, whereas RF sputtering alternates its electric charge, which makes it able to avoid the charge building up on the target material.
Both methods are beneficial and efficient ways to create thin films, but DC sputtering does offer a higher deposition rate than RF sputtering. DC sputtering is also much more useful when you’re working with large substrate materials, whereas RF sputtering is normally the preferred method with smaller substrates.
What benefits does DC sputtering offer that RF sputtering doesn’t?
If you’re looking for a simple and economical method of producing thin films, most manufacturers will choose DC sputtering. This is mainly because this process offers a lot of benefits that other processes – including RF sputtering – can’t provide.
When you use a DC sputtering process to create thin films, you can benefit from cost-savings and wider profit margins. DC power runs on simple, affordable configurations that can be adapted for use with a range of magnetic sputtering targets like nickel or iron.
However, although DC sputtering is a very popular method of creating thin films, it doesn’t come without its flaws too. It’s not the ideal process to use when you’re working with non-conductive, insulating materials, as the materials may take on an electric charge and harm the target material.
What is the best choice for precision thin film coating?
If precision is the most important thing to you when creating thin film coatings, there is a clear winner between radio frequency sputtering and direct current sputtering.
Most manufacturers will always choose direct current sputtering because it’s the method that offers the most control throughout the manufacturing process.
When you use direct current as a power source, you can benefit from increased precision and versatility within the chamber pressure vacuum, which you can’t achieve with other processes.
You can apply this manufacturing method to a range of different thin-film materials, which makes it very versatile. So, if you’re working on a range of products and want to choose one method that’s going to work for everything, you can rely on direct current sputtering.
In this article, we’ve taken you through everything you might need to know about radio frequency sputtering and direct current sputtering.
Although they may sound like similar processes that are used to create thin films, there are a few major differences between the two techniques. Depending on the type of thin film you want to create, and what materials you’re working with, there should be an easy choice to make between the two.
If you’d like to learn more about thin film technology and sputtering techniques, read more on the Korvus Technology blog, here.