Characteristic Requirements of Molybdenum Sputtering Target

In the electronics industry, molybdenum sputtering targets are widely used in flat panel displays, electrodes and thin film solar cells based on molybdenum’s high melting point, high conductivity, low specific impedance, good corrosion resistance and good environmental performance. Wiring materials and semiconductor barrier materials. Molybdenum sputtering targets are divided into two types according to their shapes, one is a flat plate target, and the other is a tubular rotating target. In order to improve the sputtering efficiency and ensure the quality of the deposited film, the characteristics of the molybdenum sputtering target have the following requirements.

1) Purity

High purity is a basic characteristic requirement for molybdenum sputtering targets. The higher the purity of the molybdenum target, the better the performance of the sputtering film. Generally, the purity of the molybdenum sputtering target needs to be at least 99.95%.

2) Density

During the sputtering coating process, when the less dense sputtering target is bombarded, the gas in the voids inside the target is suddenly released, causing large-size target particles or particles to splash, or the film is formed after the film is formed. Particles splash due to secondary electron bombardment. The appearance of these particles will reduce the quality of the film. Therefore, the sputtering target is generally required to have a higher density, reduce the lift-off in the target solid, and improve the performance of the film. For molybdenum sputtering targets, the relative density should be more than 98%.

3) Grain size and size distribution

The molybdenum sputtering target has a polycrystalline structure, and the crystal grain size can be on the order of micrometers to millimeters. The sputtering rate of the fine-grained target is faster than that of the coarse-grained target; while the target with a smaller difference in the crystal grain size has a more uniform thickness distribution of the deposited film.

4) Crystal orientation

During sputtering, the target atoms are easily sputtered out along the most densely arranged directions of the hexagonal atoms. Therefore, in order to achieve the highest sputtering rate, the sputtering rate is often increased by changing the crystalline structure of the target.

5) Binding of target material and chassis

Generally, the molybdenum sputtering target must be connected with the oxygen-free copper (or aluminum and other materials) chassis before sputtering, so that the target and the chassis are in good thermal and electrical conductivity during the sputtering process. After binding, it must be ultrasonically inspected to ensure that the non-bonding area of the two is less than 2%, so as to meet the requirements of high-power sputtering and not fall off.