1. A method comprising: carrying out a first manufacture step having at least one first variable, the first manufacture step resulting in a first intermediate feature; measuring a first characteristic of the first intermediate feature; carrying out a second manufacture step having at least one second variable, the second manufacture step resulting in a second intermediate feature; measuring a second characteristic of the second intermediate feature; modeling a final characteristic of a final feature using a model based on at least one of the first variables and at least one of the second variables and at least one of the first and second characteristics; measuring the final characteristic; comparing the modeled final characteristic and the measured final characteristic by estimating disturbances for the first and second manufacture steps based on a model of the first and second manufacture steps, wherein the estimating is performed using a Kalman filter; updating the model; modifying at least one of the first variable and the second variable to optimize the final characteristic; and carrying out the first and second manufacture steps using the modified at least one of first and second variables.