Sliding Mode Control of a Distributed-Parameter Wafer Spin Clean Process

In this study, a temperature controller for chemical fluids, which are impinged on a rotating silicon wafer, is presented. The chemical fluid is heated by a heating plate that is mounted below the rotating wafer. The thermal behavior of the system is modeled as a distributed-parameter system. In order to deal with this problem setting, a second-order sliding mode controller is proposed. The controller is inspired by the finite-dimensional generalized super-twisting algorithm. Finite-time convergence despite the presence of a certain class of disturbances is proven by means of a Lyapunov function. The algorithm is implemented and tested on the real system.