A series of study of trench dislocation occurred in 0.13/0.18um CMOS technologies have been done. First, it is demonstrated for the first time that trench crystal dislocations can be detected successfully using current mapping atomic force microscopy (C-AFM). Different from conventional voltage contrast technique, which uses SEM image brightness for the comparison of leaky contacts/junctions and normal ones, C-AFM probes the surface of samples by contacting them directly and can provide I-V curve mapping data for each contact/junction where the needle passes. Thus a quantified contact/junction leakage current data is acquired and can be used to find out minor trench dislocation (located beneath the leaky contact), which works as a leakage source negligible before but crucial in 0.13um low power devices. Besides, a model concerning about the FEOL overall thermal budget is proposed to explain the formation of trench dislocations.