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sputter coating
Unbalanced magnetron sputtering

If the magnetic fluxes of the inner and outer magnetic pole sections of the cathode by magnetron sputtering are not equal, it is called an unbalanced magnetron sputtering cathode. The magnetic field of the common magnetron sputtering cathode is concentrated near the target surface; the magnetic field of the unbalanced magnetron sputtering cathode radiates a large amount of ordinary magnetron cathode magnetic field outside the target field, and the plasma is tightly constrained near the target surface. The plasma near the substrate is weak, and the substrate is not bombarded by ions and electrons. The unbalanced magnetron cathode target field spreads the plasma away from the target surface, immersing the substrate therein.

sputter coating

Radio frequency (RF) sputtering

A negative potential is applied to the conductor placed on the back side of the insulating target. In the plasma of the glow discharge, when the positive ion accelerates to the guide plate, the front insulating target is bombarded and sputtered. The sputtering can only be maintained for 10-7 seconds, after which the positron accumulated on the insulating target plate cancels the negative potential on the conductor plate, thus stopping the bombardment of the insulating target by the high energy positive ions. At this time, if the polarity of the power source is reversed, the electrons will bombard the insulating plate and neutralize the positive charge on the insulating plate in 10-9 seconds to make it zero. And if the polarity of the power source is reversed again, it can generate a sputtering for 10-7 seconds.

Direct current (DC) magnetron sputtering

The magnetron sputtering coating device adds a magnetic field to the DC sputtering cathode target, and uses the Lorentz force of the magnetic field to bind and extend the trajectory of the electron in the electric field, increasing the collision chance between the electron and the gas atom as well as the ionization of the gas atom, which increases the high energy ions bombarding the target and decreases the high energy electrons bombarding the plated substrate.

Mid-frequency alternating current (AC) magnetron sputtering

In a mid-frequency AC magnetron sputtering device, two parallel-sized targets of the same size and shape are often referred to as twin targets. In the mid-frequency AC magnetron reactive sputtering process, two targets are usually simultaneously powered and alternately used as an anode and a cathode. When the target is at a negative half-cycle potential, its surface is sputtered by positive ion bombardment; while in the positive half cycle, the plasma electrons are accelerated to reach the target surface, neutralizing the positive charge accumulated on the target surface. This not only suppresses the ignition of the target surface, but also eliminates the phenomenon of “disappearing anode”.

Reactive magnetron sputtering

The reaction gas is supplied during the sputtering to react with the sputtering particles to form a compound film. It can react with the reaction gas while sputtering the compound target, or can react with the reaction gas while sputtering the metal or alloy target to prepare a compound film of a predetermined chemical ratio.


Stanford Advanced Materials(SAM) is a global sputtering targets manufacturers which supplies high-quality and consistent products to meet our customers’ R&D and production needs. Please visit our website for more information.

About the author

Julissa Green graduated from the University of Texas studying applied chemistry. She started her journalism life as a chemistry specialist in Stanford Advanced Materials (SAM) since 2016 and she has been fascinated by this fast growing industry ever since. If you have any particular topics of interest, or you have any questions, you can reach her at julissa[email protected]