Research of Magnetron Sputtering Plasma Characteristics and Load Matching Based on Pulse Bias

A well performing thin film can be obtained by adding pulse bias on the magnetron sputtering substrate. However, serious load voltage oscillation, caused by the capacitive component in the plasma load, affects thin film deposition. The paper analyzes the cause of producing oscillation theoretically based on the magnetron sputtering plasma load equivalent circuit loop model. Although the voltage oscillation can be suppressed effectively by joining inductor or a series unit of resistor and inductor between pulsed voltage power and load circuit, the rising rate of pulsed voltage is reduced significantly. Considering this problem, a matching circuit with series inductors and diodes connected in parallel unit in load loop is introduced in the paper. Inductor inhibits oscillation and plays the role of current limiter. Freewheel diode accelerates the rising rate of voltage when the pulse voltage changes direction. Simulation and experimental verification were conducted, indicating that the method ensures the film quality by suppressing oscillation and improving the rising rate of pulsed voltage at the same time.