The delamination strength of interface between Cu and TiN thin films considering the internal stress in the films is evaluated. The results show that the combination of intensified stresses due to the applied load and the internal stress governs the crack initiation at the interface edge, and the toughness at the Cu/TiN interface edge is evaluated by the stress intensity factor on the basis of the fracture mechanics concept. An experimental method for evaluating the interface strength of micro-component on a substrate is also developed using a modified atomic force microscopy. A diamond tip is dragged along the surface of Si substrate with a micro W piece, and the lateral as well as the vertical load and displacement are continuously monitored during the test. After the tip hits the W piece, the lateral load increases in almost proportion to the lateral displacement. The piece is abruptly separated from the substrate along the interface. Then, the apparent fracture energy of the interface between W and Si is successfully evaluated.