Pii: S1359-6454(99)00270-0

ÐNanoindentation for measuring thin ®lm mechanical properties is probably the most popular yet ill-understood method due to its inherent complexities. As opposed to burst pressure or microtensile tests of lithographed structures, where relatively uniform stress ®elds may be generated, the indentation-induced stress gradients can produce unique challenges. Because of the test's simplicity and ability to mechanically probe the smallest of scales, it is becoming increasingly applied. Five possible stages of deformation are suggested from Hertzian elastic to ®lm delamination and double buckling. In particular metal ®lms on harder substrates are emphasized where it is shown that dislocation nucleation and arrest are only partially understood. Later stages of ®lm delamination are illustrated with Cu/SiO2/Si where it is shown that the true work of adhesion is 0.6 J/m. Current limitations of indentation-induced delamination measures of toughness involve large scatter associated with sensitivity of the fracture radius to the contact radius ratio. # 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.