Fatigue study of nano-scale silicon nitride thin films using a novel electrostatic actuator

We report for the first time the fatigue study of nanoscale silicon nitride (SiN) thin films using a novel electrostatic actuator. The mechanical-amplifier (MA) devices made in SiN thin films can apply controllable tensile stress (2.0-7.8 GPa) to test structures with relatively low actuation voltages (5.7-35.4 VRMS) at their resonant frequencies. With the recently developed experimental techniques inside a focused-ion-beam (FIB) system, in-situ fatigue measurements are performed on SiN test structures with a linewidth of 200 nm. The SiN test structures are found to exhibit time-delayed failures with a continuous increase in their compliance. By reducing the applied tensile stress to 3.8 GPa, the test structures can survive cyclic loadings up to 10 cycles.