AVS 45th International Symposium
    Thin Films Division Wednesday Sessions
       Session TF-WeA

Paper TF-WeA5
Using Pulsed DC Power for Reactive Sputtering of Al@sub 2@O@sub 3@

Wednesday, November 4, 1998, 3:20 pm, Room 310

Session: Advances in Sputtering
Presenter: A. Belkind, Stevens Institute of Technology
Authors: A. Belkind, Stevens Institute of Technology
A. Freilich, Stevens Institute of Technology
R. Scholl, Advanced Energy Industries
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Implementation of reactive sputtering of dielectrics such as Al@sub 2@O@sub 3@ by the use of steady DC power is obstructed by arcing. The arcing appears to be due to breakdown of the dielectric (oxide) films that grow on the metal target surface and which accumulate positive charges on their surfaces due to ion bombardment. The arcing can be greatly alleviated when pulsed DC power is applied. By pulsed DC power we mean that the power is applied for a short "on" period, and then removed for a short "off" period. During the "off" period the plasma can discharge the surfaces, provided certain conditions are met. The dependence of adequate discharging, and thus arc prevention, on the duration of the "on" and "off" periods is examined. In addition, the dynamics of plasma density loss in the "off" period and its re-establishment in the initial part of the "on" period are discussed. Reactive sputtering takes place only during the "on" period, and part of this period is lost for effective sputtering due to the necessity for full plasma re-establishment. This produces a dependence of the deposition rate on both the duty cycle and the frequency of pulsing, but not on the power. This dependence is examined and the power efficiencies of AC and pulsed power DC reactive sputtering are compared and speculation made as to the differences in results published between single and dual cathode systems.