FIELD OF INVENTION

The present invention relates broadly, but not exclusively, to sputtering systems and methods.

BACKGROUND

Sputtering is a process in which particles in a solid target material are ejected from its surface due to bombardment by energetic particles. Sputtering has been used in various industries to deposit thin films onto a substrate.

In optoelectronics and valleytronics, it has observed that the transition metal based two-dimensional materials such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) exhibit promising applications.

Based on the above understanding, WO 2016/013984 A1 describes a deposition process to synthesize wafer-scale MoS2atomic layers on diverse substrates via magnetron sputtering, which enables large-area deposition of transition metal dichalcogenide films in a controllable way. Films can be grown by a layer-by-layer mode with good uniformity and over large areas. The method can be further scaled up to a large area sample for industry applications. In this way, it is compatible with industry mass production techniques on wafer level.

However, due to the bombardment effect on the surface of the grown sample during sputtering process, a higher defect density has been seen in the thin films. In other words, a shortcoming of the above approach is that bombardment damage to the film surface is expected to be high.

A need therefore exists to provide a sputtering system and method that seek to address at least some of the above problems.

SUMMARY

An aspect of the present disclosure provides a sputtering system comprising: a first electrode comprising an elongated tube having a first end and a second end downstream of the first end, wherein the first end is configured to receive a gas flow and the second end is placed next to a substrate; a magnet surrounding at least a portion of the elongated tube and configured to generate a magnetic field in a space within the elongated tube; and a second electrode disposed within the elongated tube. A voltage is configured to be applied between the first and second electrodes to generate an electric field between the first and second electrodes.

The first electrode may comprise a cathode and the second electrode may comprise an anode. Alternatively, the first electrode may comprise an anode and the second electrode may comprise a cathode.

The first and second electrodes may be made of the same material. Alternatively, the first and second electrodes may be made of different materials.

At least one of the first and second electrodes may be made of a transition metal, and the gas flow may comprise a chalcogen vapor.

The transition metal may comprise Molybdenum or Tungsten.

The tube may be substantially cylindrical and the second electrode may comprise a rod disposed along a longitudinal axis of the tube.

The system may further comprise control means for controlling at least one of a partial pressure of the gas flow, a strength of the magnetic field, a strength of the electric field, a sputtering duration, and a temperature of the substrate.

Another aspect of the present disclosure provides a sputtering method. The method comprises providing a sputtering system, generating a sputtered material, and depositing the generated sputtered material exiting the second end of the elongated tube onto the substrate. The sputtering system comprises a first electrode comprising an elongated tube having a first end and a second end downstream of the first end, wherein the second end is disposed adjacent a substrate; a magnet surrounding at least a portion of the elongated tube; and a second electrode disposed within the elongated tube. Generating the sputtered material comprises: generating a magnetic field in a space within the elongated tube using the magnet; applying a voltage between the first and second electrodes to generate an electric field between the first and second electrodes; and supplying a gas flow to the first end of the elongated tube to generate a discharge.

Applying the voltage between the first and second electrodes may comprise using the first electrode as a cathode and the second electrode as an anode. Alternatively, applying the voltage between the first and second electrodes may comprise using the first electrode as an anode and the second electrode as a cathode. The method may further comprise alternating a direction of the electric field between the first and second electrodes.

Providing the sputtering system may comprise selecting the first and second electrodes to be of the same material. Alternatively, providing the sputtering system may comprise selecting the first and second electrodes to be of different materials.

Providing the sputtering system may further comprise selecting at least one of the first and second electrodes to be made of a transition metal, and supplying the gas flow may comprise supplying a chalcogen vapor in the gas flow.

The transition metal may comprise Molybdenum or Tungsten.

Providing the sputtering system may further comprise providing a substantially cylindrical tube and disposing a rod along a longitudinal axis of the tube.

The method may further comprise controlling at least one of a partial pressure of the gas flow, a strength of the magnetic field, a strength of the electric field, a sputtering duration, and a temperature of the substrate.

Depositing the generated sputtered material may comprise depositing the material as a two-dimensional (2D) film.

