CAPACITANCE OF TOP LEADS METAL - COMPARISON BETWEEN FORMULA, SIMULATION, AND EXPERIMENT

The parasitic interconnection capacitance can significantly degrade th e performance of an IC, In this paper, the parasitic capacitance of th e top leads with a protective overcoat (PO) dielectric is modeled. For a nitride only PO, the nitride increases the line-to-line capacitance component by the average of the nitride and underlying oxide dielectr ic constants with a maximum error of 11% according to two-dimensional numerical simulations. If the oxide thickness of the PO is greater tha n 0.2 mu m, then the line-to-ground component of capacitance will be w ithin 10% of the value of a lead surrounded by oxide. The line-to-line component of capacitance can have an error of over 30% and a modifica tion is required to reduce the error. Two modifications for the nitrid e/oxide PO are given; both increase the line-to-line capacitance by th e fraction of nitride between the leads. The results of the modificati ons and simulation are compared to experiment. The two-dimensional sim ulations and formulas have a good fit to the experimental data.