Mechanical properties measurement of PECVD silicon nitride after rapid thermal annealing using nanoindentation technique

This paper presents the results of mechanical characterisation of residual stress, elastic modulus, hardness and fracture toughness of plasma-enhanced chemical vapour deposited (PECVD) silicon nitride films subjected to rapid thermal annealing (RTA), processed between 200 and 800 degrees C. Additional tensile residual stresses were generated during the RTA period and the stress reached peak values after a 400 degrees C RTA process. On the other hand, nanoindentation testing revealed that both the modulus and hardness varied significantly with different RTA temperatures. Finally, the fracture toughness of the nitride was estimated to be 1.33 MPa root m based on a series of Vickers micro-indentation tests and it can be enhanced by the RTA process. These results should be useful for microelectromechanical systems (MEMS) or integrated circuit (IC) structure fabrication as regards maintaining the structural integrity and improving fabrication performance.