AVS 56th International Symposium & Exhibition
    Plasma Science and Technology Thursday Sessions
       Session PS2-ThM

Paper PS2-ThM12
Damage-Free, Uniform and High-Target-Utilization Novel Magnetron Sputtering Plasma Source by Rotating Helical Magnet

Thursday, November 12, 2009, 11:40 am, Room B2

Session: Plasma Sources
Presenter: T. Goto, Tohoku University, Japan
Authors: T. Goto, Tohoku University, Japan
N. Seki, Tokyo Electron Technology Development Institute, Inc., Japan
T. Matsuoka, Tokyo Electron Technology Development Institute, Inc., Japan
T. Ohmi, Tohoku University, Japan
Correspondent: Click to Email
Novel magnetron sputtering equipment, called rotation magnet sputtering (ROT-MS), is being developed to overcome various disadvantages of current magnetron sputtering equipment. Disadvantages include:(1) very low target utilization of less than 20%, (2) difficulty in obtaining uniform deposition on the substrate, and (3) charge-up damages and ion-bombardment-induced damages resulting from very high electron temperature and that the substrate is set at the plasma-excitation region. In ROT-MS, a number of moving high-density plasma loops are excited on the long rectangular flat target surface by rotating helical magnets, and the deposition is performed by passing the substrate through this deposition region, resulting in very high target utilization with uniform target erosion and uniform deposition on the substrate due to time-averaging effect. T his excellent performance can be principally maintained even as equipment size increases for very large-substrate deposition. Plasma characteristics and deposition performances were investigated using ROT-MS equipment for both 8-inch wafer and 200-mm-square substrate. Deposition uniformity on 8-inch wafers for pure Al deposition results in that the film-thickness uniformity (defined by standard deviation divided by average thickness) is 0.5～2.5% in the wide pressure range from 0.33 to 5.3 Pa for the cases without any optimization of slit width configuration. The target utilization is estimated to be 59.7% from the measurement of the target erosion distribution. It is found that the target erosion distribution experimentally observed agrees well with the theoretical calculation. We have calculated target utilization for various helical magnet configurations, and revealed that very high target utilization larger than 90% is feasible. Detailed ion current distributions at the substrate were measured by measuring ion saturation currents flowing to the multipoint probes set at the stage (in this measurement, the helical magnet is not rotating). The results show that the distribution is uniform within the slit area for the rf-excited plasma case with the order of 1 mA/cm2, while the distribution of the magnetic filed loop pattern is observed with the order of 0.1 mA/cm2 for the dc-excited case. Because strong horizontal magnetic fields (>0.05 T) are produced within a very limited region just at the target surface, very low electron-temperature plasmas (< 2.5 eV for Ar plasma, and < 1 eV for direct-current-excited Xe plasma) are excited at the very limited region adjacent to the target surface for charge-up damage-free and ion-bombardment-induced damage-free processes.