1. A method of monitoring end-point traces of a plasma etch reactor comprising: establishing a reference end-point trace for a predetermined etch process; dividing the reference end-point trace into predefined regions; conducting the predetermined etch process on a semiconductor device; obtaining an actual end-point trace for the etch of the semiconductor device; dividing the actual end-point trace into candidate regions in accordance with predefined criteria based on changes in said actual trace; matching candidate regions of the actual end-point trace with corresponding regions of the reference end-point trace by analyzing characteristics of a candidate region of the actual end-point trace over characteristics of a region of the reference end-point trace to be matched; and comparing characteristics of regions of the actual end-point trace with corresponding characteristics of matched regions of the reference end-point trace.