On the Charge Build-Up Mechanisms in Very Thin Insulator Layers

The volume degradation features of very thin tunnel oxide layers will be deeply analyzed and the validity of the following issues will be demonstrated quantitatively: i) only negative charge builds-up in the bulk of the insulator layer, ii) for a given oxide thickness and gate stress polarity breakdown occurs as soon as the negative trapped bulk oxide charge density attains a critical value, iii) the stress-induced bulk oxide charge distribution centroid displacement direction does not depend on the insulator thickness and iv) independently of the insulator thickness, the stress-induced evolution of the bulk oxide trapping properties can be explained with a generalized power degradation law. Furthermore, the breakdown parameters of these thin films will be studied in details.