Fractional-Order Stochastic Extremum Seeking Control with Dithering Noise for Plasma Impedance Matching

Impedance matching is critical to ensure the maximum power transfer on plasma etching for semiconductor manufacturing. However, it is a challenging task due to the unknown and complex plasma dynamics. In this paper, a Stochastic Perturb and Observe Fractional-Order Extremum Seeking Controller (P&O FO-SESC) is employed for plasma impedance matching. The controller uses a Fractional-Order Gaussian (dithering) Noise (fGn) as the perturbation signal and is tested for an L-type matching network with two variable capacitors. Obtained results show that the Stochastic P&O FOESC controller improves the impedance matching convergence zone over the standard P&O ESC controller for different loads and initial conditions.