ELECTROSTATIC ADHESION TESTING OF ELECTRONIC METALLIZATIONS

A novel technique is developed to measure quantitatively the adhesion strength of metallizations deposited on substrates such as silicon. El ectrostatic adhesion testing employs electrostatic forces to generate delaminating stresses in thin metallic films. The interfacial adhesion strength is readily calculated from the electrode geometry and the ap plied electrostatic field at failure. Unlike other adhesion tests, thi s technique does not require any mechanical contact and is virtually i ndependent of the plastic deformation of the film. Furthermore, this t est provides direct strength measurements as opposed to work or energy of adhesion measurements obtained by the common peel test. The adhesi on strengths of several metallizations (Cu, Al) are characterized usin g the electrostatic technique. The distribution of stress-at-failure d ata follows Weibull failure statistics. Field emission scanning electr on microscopy reveals that the films are delaminated in a microblister -type mode. It is shown that electrostatic adhesion testing is effecti ve in providing quantitative values for the adhesion strengths and fai lure probabilities of thin-film metallizations. (C) 1997 American Inst itute of Physics.