The Influence of Fabrication Governed Surface Conditions on the Mechanical Strength of Thin Film Materials

Abstract

ABSTRACTThe mechanical strength of thin polysilicon films has been examined in connection with exposure to Hydrofluoric Acid (HF). It is found that surface roughness as characterized by groove formation at grain boundaries depends on the HF release time. Surface undulations and crevasses related to grain structure result in reduced fracture strength and induced errors into the effective elastic modulus measurements - especially when the latter is determined from flexure configurations. Extensive exposure to HF results in material degradation, as evidenced by a transition from a transgranular to an intergranular failure manner and a corresponding drastic drop of the film strength with attendant increase of porosity.