Design and analysis of manufacturable alternating phase-shifting masks

The advent of mask topography simulation has made possible not only the investigation of the effects of scattering from the mask on the aerial image quality, but also allows a search for mask configurations that produce the desired results. In this work, we first provide studies of the effective phase in a phase-shifting mask by varying both the relative subtractive etch depth in the quartz (corresponding to the Kirchhoff phase difference) and the etch bias (dual trench depth). Ultimately, the sensitivity of the resist linewidth with respect to the effective phase error takes on a critical importance in production, and one may desire to know how to alter a given mask in order to eliminate undesired effects from such errors. A design methodology that takes these issues into account employing a mask topography simulator and a lithography simulator is the end result of this study and is illustrated using an example taken from sub-130 nm lithography.