1. A method for manufacturing semiconductor devices comprising: an inspection step of inspecting semiconductor substrates processed until a predetermined sub-process for defects or suspected defects occurred to the semiconductor substrates, with an inspection equipment, in a fabrication line consisting of a plurality of sub-processes arranged in sequence, each sub-process being performed by one or a plurality of manufacturing equipments; and a step of collecting and analyzing inspection results, wherein said step of collecting and analyzing inspection results comprising: a step of generating a defects distribution on a semiconductor substrate in order to investigate the cause of the defects, based on the inspection results obtained from said inspection step; a step of quantitatively evaluating defect features of the defects distribution on a semiconductor substrate generated by said step of generating a defects distribution; a step of generating data of the defect features quantitatively evaluated by said step of quantitatively evaluating defect features for the manufacturing equipments that processed the semiconductor substrates and the sub-processes that applied to the semiconductor substrates; and a causation inferring step of evaluating cyclicity of the defect features data for the manufacturing equipments that processed the semiconductor substrates and the sub-processes that applied to the semiconductor substrates, generated by said step of generating data, thereby inferring a causal manufacturing equipment that caused the defects.