Impact of mask errors on full chip error budgets

As lithography pushes to smaller and smaller features under the guidance of Moore's Law, patterned features smaller than the wavelength of light must be routinely manufactured. Lithographic yield in this domain is directly improved with the application of OPC (Optical and Process Correction) to the pattern data. However, such corrections generally assume that the reticle can reproduce these features exactly. The Mask Error Enhancement Factor (MEEF) serves to amplify reticle errors, and can reduce the benefits of OPC in some circumstances. In this paper, we present the characterization of the MEEF for contact holes. These are found to have significantly higher values for the MEEF than typically measured for isolated lines. Theoretical predictions are compared with experimental results. Good agreement is found at the center of the field only when the actual area of the contact hole as formed on the reticle is used as the metric of contact size. Across field variation, however, is found to be significant requires characterization for optimum yield to be achieved.