Charge based transient current testing (CBT) for submicron CMOS SRAMs

We analyze a transient current testing technique that measures and computes the charge delivered to the circuit during the transient operation. The method was applied to 0.5 μm CMOS SRAMs that passed various logic tests. Results indicate that charge based testing (CBT) can successfully test submicron ICs since it tolerates large and variable background currents, can be applied to non-fully static circuits, and clearly shows outlier parts. CBT is a sensitive physical test correlating transient charge injected to the properties of particular transistors that switch during selected patterns. This gives CBT an efficient diagnostic capability. A compact hardware module to compute CBT was demonstrated previously.