A comprehensive assessment of contact oxide etch damage using device monitor and in-line noncontact testing

We report here a direct correlation between a Keithley Quantox in-line tester and full-flow device monitors for contact oxide etch damage. Gate leakage measured with the device monitor were used to choose the least damaging of four oxide etchers. The same ranking was confirmed using Quantox flatband voltage measurements, but with a much faster turnaround time. Also, the Quantox capabilities were used to isolate the primary contributors of damage in one particular reactor, and the resulting reduction in damage was confirmed with the test monitors. The capability to quickly isolate specific portions of a recipe is demonstrated here, and it is subsequently confirmed with the full-flow device monitor. The advantage of using this technique in conjunction with a full-flow device monitor results in a much faster turn around for isolation of plasma damage