TOF-SIMS Analytical Method for Gate Oxide Breakdown Voltage Shift Failure

Traditional failure analysis for gate oxide (GOX) breakdown voltage (BV) shift involves electrical fault isolation of the defect and wright etch to discriminate plasma induced defects or contamination. To further nail down the root cause of the contamination, secondary ion mass spectrometry (SIMS) is proposed due to its superior detection sensitivity at ppm or ppb level and superior mass resolution to determine the foreign elements or materials unambiguously. In this paper, a PMOS device failure was found to be gate oxide breakdown voltage shifted down. Time-of-Flight (TOF) -SIMS depth profile is thus used for the all-elements search mode analysis to figure out the contamination, which is consistent with the inline process commonality analysis results.