Fracture toughness of amorphus SiC thin films using nanoindentation and simulation

Fracture toughness of SiC on Si thin films of thicknesses of 150, 750, and 1500 nm were measured using Agilent XP nanoindenter equipped with a Dynamic Control Module (DCM) in Load Control (LC) and Continuous Stiffness Method (CSM) protocols. The fracture toughness of the Si substrate is also measured. Nanovision images implied that indentations into the films and well deep into the Si caused cracks to initiate at the Si substrate and propagate upward to the films. The composite fracture toughness of the SiC/Si was measured and the fracture toughness of the SiC films was determined based on models that estimate film properties from substrate properties. The composite hardness and modulus of the SiC films were measured as well. For the DCM, the hardness decreases from an average of 35 GPa to an average of 13 GPa as the film thick increases from 150 nm to 1500 nm. The hardness and moduli of the films depict the hardness and modulus of Si at deep indents of 12 and 200 GPa respectively, which correlate well with literature hardness and modulus values of Si. The fracture toughness values of the films were reported as 3.2 MPa√m.