US Patent 7382055 Integrated thin-film resistor with direct contact

A BEOL thin-film resistor adapted for flexible integration rests on a first layer of ILD. The thickness of the first layer of ILD and the resistor thickness combine to match the nominal design thickness of vias in the layer of concern. A second layer of ILD matches the resistor thickness and is planarized to the top surface of the resistor. A third layer of ILD has a thickness equal to the nominal value of the interconnections on this layer. Dual damascene interconnection apertures and apertures for making contact with the resistor are formed simultaneously, with the etch stop upper cap layer in the resistor protecting the resistive layer while the vias in the dual damascene apertures are formed.