Sputtering targets used in RF sputtering

Sputtering is widely used in industrial process because it can obtain high quality films at low temperature substrates. It is a cheap and versatile technique to deposit alternating layers of different materials with controlled refractive index and thickness.

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RF sputtering (Radio Frequency Sputtering) is an important method of sputter coating. It is the technique involved in alternating the electrical potential of the current in the vacuum environment at radio frequencies to avoid a charge building up on certain types of sputtering target materials In RF sputtering, there are a cathode (the sputtering target) and an anode, and they are in series with a blocking capacitor (C). These three components are indispensable in the RF sputtering system.

The capacitor is an important part of the impedance-matching network that proves the power transfers from the RF source to the plasma discharge.

As its name suggest, in RF sputtering, the power supply is a high voltage RF source, which is often fixed at 13.56 MHz.

The blocking capacitor C is placed in the circuit to develop the all-important DC self-bias, and a matching network is utilized to optimize power transfer from the RF source to the plasma.

RF-sputtering offers advantages over DC; in particular sputtering of an electrically insulating target become possible. The main difference between these two kinds of sputter coating method is that the power used in RF sputtering is AC (Alternating Current), while the power used in DC sputtering is DC (Direct Current).

Basically speaking, the working gas will be ionized in the process of DC sputtering. And the result is that many positive ions will be produced within the chamber and accumulate on the surface of target if the conductivity of the sputtering target is not very good. In other words, actually, DC sputtering has higher requirement of the quality of the sputtering target.

RF sputtering stands out when the problem occurs. In order to avoid this problem in DC sputtering, we can use AC power instead of DC. During the positive electric field, the positive ions are accelerated to the surface of target. While in the negative field, the charging positive ions on the surface of target can be removed.

Please visit https://www.sputtertargets.net/ for more information.