2.8 A statistical approach to the analysis of dielectric breakdown strength of thin insulating films

Abstract

Statistical models that are widely used in the study of high voltage insulating systems are applied to thin insulating films. By use of these methods it is in many cases possible to decide whether the electrical strength of a component is bulk-limited or electrode-limited. A discussion on which type of statistical distribution function can be expected for electrical breakdown in thin films is given. By analyzing measured breakdown voltages for more than 2000 capacitors it has been shown that a description of dielectric breakdown in thin films by means of the theory of the weakest link is fruitful. It is shown that the first selfhealing breakdown has its origin at weak spots randomly distributed over the capacitor area. The variation in the results is too large to determine whether the breakdowns start at the interface electrode dielectric or within the bulk of the film. These techniques have also been succesfully applied to previously published results, offering an explanation of results not previously understood.