Various Contrasts Identifiable From the Backside of a Chip by 1.3μm Laser Beam Scanning and Current Change Imaging

We can identify various contrasts by scanning an 1.3 um laser beam from the backside of a chip and displaying current changes as brightness changes on a CRT, because the 1.3 um laser beam generates no OBIC signal and can penetrate P- Si substrate with little intensity degradation. The contrasts we have confirmed up to now are: (1) Current pass contrast at Al lines caused by OBIRCH, (2) Defect contrast at Al interconnects caused by OBIRCH, (3) Current pass contrast at a poly Si lines caused by OBIRCH, (4) Parasitic MIM (metal-insulator-metal) contrast caused by temperature dependence of MIM current, (5) Schottky-barrier contrast caused by internal photoemission.