The Study and Investigation of Inline E-Beam Inspection for 28nm Process Window Monitor

The research aims at the VC (voltage contrast) of contact-loop defects in 28nm processes. A new type defect, marginal via open, was found on 28nm logic product wafer and the designed inline E-beam inspection was used to detect those defects by their VC features. The mechanism of defects and the method of the enhancement of the detection were described. A golden image E-beam scan recipe is required in corresponding to the unique defect wanted and, in doing so, marginal Via open defects can be found. Since the defect can be detected instantly by E-beam inspection, and therefore an inline monitoring index can be set up. Compared to the end-of-line electrical test, this inline monitor is very much closer to the trouble process and shrinks the response time. The following process experiments and evaluation can be instantly verified and examined. Finally, the Via open defect was fixed by an optimization of VIA Etch process. Instead to the debug method of failure analysis, E-beam inspection can speed up the trouble shooting cycle time.