Experiments for 140nm and 160nm contacts were optimized through simulation on an 18% transmitting phase shift mask for KrF lithography. A transmission of 18% is shown to have the most linear aerial image behavior through focus. The simulations were run using a primitive positive photoresist model in order to predict trends in resolution and to predict when side lobes begin printing. Experiments show that the 140nm and 160nm contact holes resolve without side lobe printing through focus and through exposure. Reticle SEMs verify that a ternary contact hole mask is capable of manufacture. By adding both opaque and clear sub-resolution assist features, the experiments show contacts as small as 140nm resolve with 0.50μm focus latitude with 10% exposure latitude through pitch. Cross sectional SEMs verify that 140nm contact holes are open through pitch. Experiments with the chrome material removed show that the contact holes are larger due to the addition of zero order light as suggested by theory and show that side lobes begin to print. Experiments also prove that NA has the largest impact on resolution and exposure latitude and that σ has the largest impact on depth of focus.