Apparatus and method for production process diagnosis using dynamic time

Abstract

Operations of a plasma etch reactor (10) are monitored to detect aberrations in etching operations. A reference end point trace is defined (62) for the etch process. Regions are defined in the reference end point trace (70) with aid of a dynamic time warping matching function (84) and characteristics and tolerances for each region are defined (72-80). The etcher is run and an actual end point trace is obtained (82) from the running of the etcher. A warping function is constructed (88) between the actual trace and the reference trace. In building the warping function, candidate path segments (100) are constructed according to a minimum cumulative cost function (96). Once the regions of the reference trace and the actual trace has been matched according to an optimum dynamic time warping function path (106), characteristics of the matched regions are compared (66) to determine whether aberrations have occurred during the etch process. In an alternative embodiment, the actual trace (164) is matched to each of a library of reference traces (162,182) by dynamic time warping (166). By determining the best match, a determination can be made whether the actual trace is abnormal (174) or normal (176), and the type of abnormality.