During the FEOL characterization it had already become clear, that the wafers contained reproducible dies with lower quality properties in electrical characterization.
niologic analyzed the FEOL data of the physical and electrical characterization with spatial resolution, i.e. considering the geometric position of test structure and die position.
By analyzing the geometric information, it quickly became clear that the defective dies occurred in radial patterns. A comparison of the process parameters revealed that an additional plasma step had been added.