On the target surface cleanness during magnetron sputtering

The magnetron sputter deposition of metallic thin films usually requires high vacuum sputtering conditions to avoid the contamination of impurities on the substrate. The presence of these impurities highly influence the thin film texture and microstructure. The impurities in the ambient gas not only directly affect the substrate condition, they will also adsorb onto the target surface. As they get sputtered, they will be directed towards the substrate with energies much higher than the thermal ambient gas particles, which has a huge impact on the thin film characteristics. In this way, the target surface cleanness can play an essential role for thin film growth. To quantify the target cleanness, the compound formation on a tantalum target was studied by poisoning the target as a function of the oxygen exposure and subsequently sputter cleaning the formed compound layer in pure argon. The discharge voltage during this sputter cleaning stage contains a lot of information from which the compound layer thickness can be deduced. By studying the compound formation rate, the target surface cleanness during different sputtering conditions can be estimate