Application of feedforward and adaptive feedback control to semiconductor device manufacturing

A feedforward and adaptive feedback control methodology is developed and experimentally applied to several different processes commonly used in the fabrication of semiconductor integrated circuit devices. A circular parallel-plate capacitor with a glass (SiO₂) dielectric is manufactured on silicon wafers to illustrate the use of these control strategies in the processes of silicon oxidation, aluminum metallization, lithography, and aluminum etching. The goal is to maintain a constant capacitance value on a run to run basis regardless of disturbances or modeling errors in the processes.