1. A method for identifying an area in an uncorrected or corrected mask layout which is likely to cause manufacturing problems due to a missing or an improperly placed assist feature, the method comprising: receiving a mask layout; dissecting the mask layout into segments; and identifying a problem area associated with a segment using a process-sensitivity model which can be represented by a multidimensional function that captures process-sensitivity information; wherein identifying the problem area allows a new assist feature to be added or an existing assist feature to be adjusted, thereby improving the wafer manufacturability of the mask layout; wherein using the process-sensitivity model reduces the computational time required to identify the problem area.