Variation in Dislocation Pattern Observed in SCS Films Fractured by Tensile Test: Effects of Film Thickness and Testing Temperature

Abstract

AbstractThis paper reports a transition in the fracture behavior of micron-sized single-crystal-silicon (SCS) film in an MEMS structure for various film thicknesses and ambient temperatures. The mean fracture toughness of 4-µm-thick SCS films was 1.28 MPa at room temperature (RT), and the value increased as the film thickness decreased, reaching 2.91 MPa for submicron-thick films. The fracture toughness of 4-µm-thick film did not change for ambient temperatures ranging from RT to 60ºC. However, it drastically increased at 70ºC and reached 2.60 MPa at 150ºC. Enhanced dislocation activity in the SCS crystal near the fracture surface was observed on 1-µm-thick film at RT and 4-µm-thick film at 80ºC by high-voltage electron microscopy. This change in dislocation activity seemed to correlated with the transition in fracture behavior.