Since the semiconductor industry hit the 0.18-micron generation, device feature sizes have become increasingly smaller than the wavelength of light used by available optical-lithography equipment. In this subwavelength arena, manufacturing requirements must be handled up front in the IC design stage-while changes can still be made-to enhance quality and yield. This paper defines the components needed to get clean alternating phase-shifting masks (altPSM) that ensure the manufacturability of subwavelength circuit designs. The authors present a new design for manufacturability (DFM) approach, creating an abstract set of rules that can be used to advantage in various IC CAD tool domains, especially for 100nm and below design rules. A new methodology and algorithm are presented that can quickly and easily integrate altPSM into existing and future tools earlier in the IC design flow. Finally, experimental results show how the methodology and algorithm is used to debug process-aware designs and make them altPSM-compliant.