Silicon rooftop structures 30 µm high and of 1 µm linewidth were fabricated in a microelectronics facility using anistropic KOH etching. Aluminum-1% silicon was sputter-deposited to investigate the effects of a ductile thin film on the fracture toughness of a brittle material. The rooftop structures were indented by a Knoop indenter purposely placed off-center so that the indenter was wedge-shaped. Deformation and cracks were photographed by SEM. Crack threshold load per unit width are reported for normal cracks, running perpendicular to the roofline. Fracture toughness is calculated by first order approximation and finite element modeling using SEM measurements of the length of normal cracks. Without a thin film, values for silicon are in reasonable agreement with the literature. With a thin film of only 600 Å, fracture toughness is increased by 45%. Cracks nearly parallel to the roofline also appeared at higher load values. Characteristics of both types of cracks are discussed.