Abstract: Systems and methods are provided that facilitate semiconductor processing, including etch processes. The invention provides real-time two-dimensional etch rate control. Prior to starting an etch process, a control model is selected that relates to the etch process. A formula or function description is developed from the model and solved to obtain process parameter values that are predicted to produce the desired etch rates. During the fabrication etch process, critical dimension measurements of a polysilicon gate are obtained. From these measurements, the etch process is modified so as to achieve a desired horizontal etch rate and a desired vertical etch rate. The etch process results in a polysilicon gate having a desired rectangular profile.