The key characteristic property in semiconductor manufacturing processes is the sequence of numerous often interdependent unit process steps which result in the final IC product with well-defined electrical performance and high reliability. Besides maintaining product quality, in state-of-the-art and future IC technologies high product yield has to be assured to enable cost effective manufacturing. The cost factor is the main driver to get an idea of the tool condition and to have a simple possibility to decide if a maintenance action is necessary or not. In this research, the overall tool condition developed with reasonable grouping scheme is recipe-independently monitored and the generalized moving variance (GMV) is employed to explain the functional conditions within one tool. Abnormal tool condition can be diagnosed and drilled down to sensor level for an efficient root cause analysis.