Optical lithography is pushed more to extend to sub-wavelength region for very low k1 patterning processes; in which, alternating PSM is the solution for isolated patterns, without changing the wavelength of exposure tools' light source. With this prospect, the critical issues such as design layout complexity, light intensity imbalance between shifted and unshifted space area, and phase defect controllability have recently been studied in order to apply alternating PSM for device mass production. In this paper, we studied to find out the maximum non-printable phase defects for 130 nm and 100 nm lines by printing the wafer using a KrF DUV scanner. With the limitations of the mask making process for very small programmed defects, we made the masks with duty ratio around 1:3. After we verified the resist simulation for our test pattern by wafer printing results, printable defects for denser pattern were predicted. In addition to defect printability study, the mechanical repair tool for phase bump defects was tested using 248 nm AIMS, AFM, and CD SEM metrology as well as wafer printing. Electromagnetic Field 3 dimension simulation was also compared with commercialized 2D simulation tool for phase defect printability.