The developing role for nonlinear control design in oxide growth during rapid isothermal processing

This paper presents the preliminary development of a nonlinear controller to regulate the growth of oxide on silicon in a Rapid Isothermal Processing (RIP) system. The objective is to address one of the issues faced by the US silicon IC industry in manufacturing microelectronic structures with low power consumption, high-speed reduced size, and built-in reliability. The control design begins with a description of the dynamic growth process, this description provides a general nonlinear functional relationship between the properties of the silica, i.e., oxide thickness and compressive stress, and the control inputs, lamp power and gas flow. Based on this generic process model, the integrator backstepping approach is used to design a nonlinear, full-state feedback process controller. Included in the paper is a discussion of the use of Raman Spectroscopy as a means of measuring temperature, oxide thickness, and oxide stress during the growth process