Failure snalysis of wafer using backside OBIC method

Abstract

As a result of performing the Iddq (IC's power supply current) failure analysis on CMOS logic LSI using the backside OBIC (optical beam induced current) method, we succeeded in detecting a short circuit at an overlapped portion between a power supply line and a signal line. So far a circuit failure beneath the Al wiring has been difficult to find because the surface of LSI chip is covered by the wiring. However, we succeeded in detecting the carriers abnormally generated at a failure portion of a circuit on the chip surface by the optical energy when the backside of wafer was irradiated by an He-Ne laser. The backside OBIC technique is an effective method of failure analysis for advanced multilayer LSIs.