As per analysis result, the failure

As per analysis result, the failure as customer pointed out was occurred by short circuit failure due to a minute defect in VSP block or on VSP line. Although the defect point could not be identified, it is considered that the minute defect was caused by a minute particle accidentally generated/stuck during the wafer manufacturing.Since the state of the returned sample can be rejected by our electrical inspection, it is considered that the returned sample was operating normally while the inspection although the minute defect was formed, it has been escaped from our process, after that, it was revealed as the characteristics failure by short circuit failure at the defect point by the stress during using in the field.Since no abnormality was confirmed in the production history and the yield trend, it is judged that the failure will not occur frequently and the failure of this time was accidentally occurred.