How a Magnetron Sputtering Vacuum Coating Machine Works

Magnetron sputtering is an extremely popular vacuum coating technique used to create functional and decorative films for a wide range of applications. The technique is widely employed in the electronics industry, for example, in the production of electronic components such as microprocessors, memory chips, microcontrollers and transistors.

The sputtering process involves the bombardment of a target material by high-voltage DC or pulsed DC, RF or AC power. The process also requires a highly-vacuum chamber and pumps to keep the environment as clean as possible.

Before the sputtering process can begin, the chamber must be filled with a suitable gas for the process. This gas is generally argon but other gases such as oxygen can also be used. The correct type of gas depends on the specific materials being deposited and what properties are required for the coating to perform its intended function.

Depending on the process you are looking for, the power system will vary, but all have the same core principle: high voltage DC or pulsed DC power flows through the cathode where the sputter gun and target material sit. This power must ramp up from a lower voltage before fully triggering the deposition process.

The cathode itself is mounted above the substrate and can be round or rectangular in shape to suit your application requirements. The round configuration is best for single substrate systems, while the rectangular cathode is ideal for in-line systems.

When the sputtering process is complete, it’s time to load the substrate into the main disposition chamber and prepare it for deposition. This is typically done by attaching it to a substrate holder that holds the substrate and secures it within the chamber. The holder may also have an option to load the substrate in and out without compromising the vacuum level.

In many magnetron sputtering systems, the substrate is loaded into the deposition chamber through a gate, allowing it to move in and out of the load lock chamber without compromising the vacuum environment. This prevents damage to the substrate or materials, and allows for a quick change of deposition material.

Once the substrate is loaded, it’s placed inside the main deposition chamber where a sputter gun with the desired coating material and a sputter gun for the gas to be pumped into the chamber will be located. Once the gas is in place, a strong magnetic field behind the target material creates the conditions for sputtering to occur.

During the sputtering process, high-energy charged ions eject from the target material onto the substrate. This ions have a high ion density, making them relatively stable in the sputtering atmosphere and giving rise to high deposition rates. The ion morphology of the material sputtered on the surface will depend on several factors, including the ion polarisation angle and the surface binding energy of the ions.

The sputtering ion density and sputtering rate of the metal atoms will also be affected by the pressure at which the plasma is created, i.e. the mTorr pressure, which can range from 10-3 to some 10-2. The sputtering rate of materials such as insulators and conducting materials will be reduced due to the lower ion ionization potentials of these materials.
Magnetron Sputtering Coating Machine