Experimental verification of a novel electrical test structure formeasuring contact size

An electrical test structure that measures contact size without reliance on contact resistivity measurements is presented. A comparison with SEM photographs shows that the structure measures contact size in the range of 1.0 μm with a resolution close to 0.2 μm. Results are shown for measuring the size of contacts to poly, but the concept should also apply to measuring contacts to active areas, or contacts between two metal layers. In addition to the size of contacts to poly, the structure presented also measures the linewidth and sheet resistance of the poly, and misalignment of contacts to poly. It consists of a digital vernier of 72 samples and a linewidth structure and is implemented without active circuitry in a 2 by 12 pad array using three masking levels