Stress-Induced Transistor Degradation Studied by an Indentation Approach

The strain impact on integrated circuit performance is investigated by applying a novel indentation technique. The approach aims to investigate stress caused by CPI, particularly highly localized stress/strain with respect to the actual device geometry. Non-destructive elastic indentation is used to induce homogenous stress fields in the vicinity of the test structure by applying a contact with a spherical tip. Strain-sensitive ring oscillator structures manufactured in the 22 nm FDSOI CMOS technology node are designed to monitor the device and simultaneously the NMOS and PMOS strain behavior separately. Complementary FE-simulations provide a deeper insight into the obtained experimental results by transferring them from contact force into the stress/strain space and validating the indentation approach. Relevant layout and indentation dependent parameters are investigated and evaluated. The simulation of the strain-induced mobility shift and the comparison with the established correlation verifies the accuracy of the approach. The results provide an insight into package-related stress and resulting transistor degradation, aiming at establishing a versatile tool to estimate the effect of specific real-usage conditions.