Two level metal structures were fabricated to test the efficacy of using an organic low K etch stop layer (OESL) in order to lower the effective dielectric constant for intralayer capacitance. The organic etch stop layer's intrinsic capacitance of 3.3 compares with that of silicon carbide (∼ 5) which constitutes the control of the experiment. This reduction represents a reduction of effective dielectric constant for the stack of about 10% to about 3.0. The process was optimized so as to achieve yield of via chains of a million 130 nm diameter vias, and effective K was measured. The target of 3.0 was achieved using this process. Interpenetration of the organic etch stop with the MSQ porous low K material was observed.